polypeptides

Abstract

The present invention provides novel beta solenoid folds, N-terminal capping sequences, C- terminal capping sequences, beta solenoid domains, linked beta solenoid domains, and polypeptides comprising the same, and their application in the field of synthetic fibres.

Description

[0001]POLYPEPTIDES FIELD OF THE INVENTIONThe present invention relates to novel beta solenoid folds, N-terminal capping sequences, C-terminal capping sequences, beta solenoid domains, linked beta solenoid domains, andpolypeptides comprising the same, and their application in the field of synthetic fibres.BACKGROUND TO THE INVENTION High performance synthetic fibres, such as aramids, typically have high tensile strength (2-6 GPa) and stiffness (50-300 GPa) but low ductility, typically extending less than 5% in length before failure. These synthetic fibres are widely used in a variety of applications, as unidirectional tows, weaves, felts, and knits, either as a fabric or as a composite. Their ability to absorb impact energy, including as flexible textiles, makes them attractive in protection applications. However, their low breathability and low thermal conductivity make them uncomfortable to wear, whilst their tendency to degrade in the presence of water, heat and light reduces service lifetime particularly after washing.In contrast, cellulosic- and protein-based natural fibres are generally comfortable to wearnext to the skin due to their high water absorbency and breathability but typically have lower tensile performance than synthetic fibres. Natural silk fibres can combine both high tensilestrength and comfort, but these protein-based materials are difficult to produce at highmolecular weight in recombinant expression systems and it is difficult to recapitulate the natural spinning mechanism. Both the molecular weight of the polymers and the spinning process are critical to achieving high performance fibres. Despite advances in synthetic textiles, there is still a need for the sustainable and commercially viable production of fibres that combine the desirable properties of natural fibres (e.g. breathable and water absorbent) with the high performance aspects of syntheticfibres (e.g. high tensile strength and stiffness).WO 2019175591 A1 discloses a concatemer of beta solenoid domains, wherein theconcatemer comprises at least two beta solenoid domains, wherein the at least two beta solenoid domains are linked by a linker, and wherein each of the at least two beta solenoid domains comprise an amino acid sequence that comprises at least four units of a consensusmotif. WO 2019175591 A1 also discloses a fibre comprising the concatemer, a textilecomprising the concatemer or fibre, and use of the concatemer, fibre, or textile in theproduction of e.g. sportswear. SUMMARY OF THE INVENTIONThe present inventors have developed new beta solenoid folds, N-terminal cappingsequences, C-terminal capping sequences, and beta solenoid domains which can be usedto obtain functional beta solenoid concatemers having improved properties (e.g. solubility,viscosity, spinnability, stretch, strength, and toughness). The present inventors have surprisingly found that compositions comprising the new betasolenoid concatemers may have a viscosity which enables easier processing of the dopesolution for wet-spinning. The present inventors have also surprisingly found that the new beta solenoid concatemers have good spinnability, allowing long fibres to be spun in a single wet-spinning run. The present inventors have also surprisingly found that the new betasolenoid concatemers may form stable fibres having high stretch ratios. The presentinventors have also surprisingly found that the fibres obtained using the new beta solenoidconcatemers have high tensile strength and toughness.In one aspect, the present invention provides a beta solenoid domain comprising orconsisting of an amino acid sequence having at least 90% identity to any of SEQ ID NOs: 51 to 79.The beta solenoid domain may comprise an N-terminal capping sequence, a beta solenoidfold, and a C-terminal capping sequence, each having a consensus sequence. In someembodiments, the beta solenoid domain comprises a beta solenoid fold comprising orconsisting of the amino acid sequence of SEQ ID NO: 6. In some embodiments, the betasolenoid domain comprises an N-terminal capping sequence comprising or consisting of the amino acid sequence of SEQ ID NO: 37. In some embodiments, the beta solenoid domain comprises a C-terminal capping sequence comprising or consisting of the amino acid sequence of SEQ ID NO: 44.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 51 to79. In some embodiments, the beta solenoid domain comprises or consists of the amino acidsequence of any of SEQ ID NOs: 51 to 79.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90% identity to SEQ ID NO: 51. In some embodiments, the betasolenoid domain comprises or consists of an amino acid sequence having at least 95%identity to SEQ ID NO: 51. In some embodiments, the beta solenoid domain comprises orconsists of an amino acid sequence having at least 98% identity to SEQ ID NO: 51. In someembodiments, the beta solenoid domain comprises or consists of an amino acid sequencehaving at least 99% identity to SEQ ID NO: 51. In some embodiments, the beta solenoiddomain comprises or consists of the amino acid sequence of SEQ ID NO: 51.In another aspect, the present invention provides a beta solenoid fold comprising orconsisting of an amino acid sequence having at least 90% identity to any of SEQ ID NOs: 23to 36. In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 23 to36. In some embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 6. In some embodiments, the beta solenoid fold comprises orconsists of the amino acid sequence of any of SEQ ID NOs: 23 to 36.In another aspect, the present invention provides an N-terminal capping sequencecomprising or consisting of an amino acid sequence having at least 90% identity to any ofSEQ ID NOs: 39 to 43. In some embodiments, the N-terminal capping sequence comprisesor consists of the amino acid sequence of SEQ ID NO: 37. In some embodiments, the N-terminal capping sequence comprises or consists of the amino acid sequence of any of SEQID NOs: 39 to 43.In another aspect, the present invention provides a C-terminal capping sequence comprisingor consisting of an amino acid sequence having at least 90% identity to any of SEQ ID NOs:46 to 49. In some embodiments, the C-terminal capping sequence comprises or consists ofthe amino acid sequence of SEQ ID NO: 44. In some embodiments, the C-terminal cappingsequence comprises or consists of the amino acid sequence of any of SEQ ID NOs: 46 to49.In another aspect, the present invention provides a beta solenoid domain comprising a betasolenoid fold comprising or consisting of an amino acid sequence having at least 90%identity to any of SEQ ID NOs: 23 to 36, an N-terminal capping sequence comprising orconsisting of an amino acid sequence having at least 90% identity to any of SEQ ID NOs: 39 to 43, a C-terminal capping sequence comprising or consisting of an amino acid sequencehaving at least 90% identity to any of SEQ ID NOs: 46 to 49, or any combination thereof.In another aspect, the present invention provides a polypeptide comprising two beta solenoiddomains of the present invention linked by a flexible linker. In some embodiments, the aminoacid sequences of the two beta solenoid domains are identical. In some embodiments, thepolypeptide comprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or atleast 99% identity to any of SEQ ID NOs: 146 to 174. In some embodiments, the polypeptidecomprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%identity to SEQ ID NO: 146. In some embodiments, the polypeptide comprises the aminoacid sequence of any of SEQ ID NOs: 146 to 174. In some embodiments, the polypeptidecomprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%identity to SEQ ID NO: 146.In another aspect, the present invention provides a polypeptide comprising at least two betasolenoid domains of the present invention, wherein the at least two beta solenoid domainsare linked by a flexible linker. In some embodiments, the amino acid sequences of the atleast two beta solenoid domains are identical. In some embodiments, the polypeptidecomprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%identity to any of SEQ ID NOs: 198 to 226. In some embodiments, the polypeptidecomprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%identity to SEQ ID NO: 198. In some embodiments, the polypeptide comprises the aminoacid sequence of any of SEQ ID NOs: 198 to 226. In some embodiments, the polypeptidecomprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%identity to SEQ ID NO: 198.The flexible linker is not particularly limited and any suitable flexible linker may be used. Insome embodiments, the flexible linker is selected from any poly-glycine linkers, poly-alaninelinkers, poly-serine linkers, glycine-rich linkers, alanine-rich linkers, serine-rich linkers,glycine- and alanine-rich linkers, glycine- and serine-rich linkers, and glycine / alanine / serine-rich linkers. In some embodiments, the flexible linker comprises or consists of the amino acidsequence (G / A / S)x, wherein x is from 3 to 50. In some embodiments, the flexible linkercomprises or consist of an amino acid sequence selected from: (Gly)3, (Ala)3, (Ser)3, GS,AG, TG, GGS, TGS, or any of SEQ ID NOs: 80-145. In some embodiments, the flexiblelinker comprises or consists of SEQ ID NO: 145. The polypeptide of the present invention may further comprise any suitable sequences. Insome embodiments, the polypeptide further comprises a tag sequence, for example a His-tag, such as SEQ ID NO: 175. In some embodiments, the polypeptide further comprises atail sequence, for example selected from any of SEQ ID NOs: 176-197.In another aspect, the present invention provides a polypeptide comprising or consisting ofan amino acid sequence having at least 90% identity to any of SEQ ID NOs: 51-79,preferably SEQ ID NO: 51. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 95% identity to any of SEQ ID NOs: 51-79,preferably SEQ ID NO: 51. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 98% identity to any of SEQ ID NOs: 51-79,preferably SEQ ID NO: 51. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 99% identity to any of SEQ ID NOs: 51-79,preferably SEQ ID NO: 51. In some embodiments, the polypeptide comprises or consists ofthe amino acid sequence of any of SEQ ID NOs: 51-79, preferably SEQ ID NO: 51.In another aspect, the present invention provides a polypeptide comprising or consisting ofan amino acid sequence having at least 90% identity to any of SEQ ID NOs: 146-174,preferably SEQ ID NO: 146. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 95% identity to any of SEQ ID NOs: 146-174,preferably SEQ ID NO: 146. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 98% identity to any of SEQ ID NOs: 146-174,preferably SEQ ID NO: 146. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 99% identity to any of SEQ ID NOs: 146-174,preferably SEQ ID NO: 146. In some embodiments, the polypeptide comprises or consists ofthe amino acid sequence of any of SEQ ID NOs: 146-174, preferably SEQ ID NO: 146.In another aspect, the present invention provides a polypeptide comprising or consisting ofan amino acid sequence having at least 90% identity to any of SEQ ID NOs: 198-6,preferably SEQ ID NO: 198. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 95% identity to any of SEQ ID NOs: 198-6,preferably SEQ ID NO: 198. In some embodiments, the polypeptide comprises or consists ofan amino acid sequence having at least 98% identity to any of SEQ ID NOs: 198-6, preferably SEQ ID NO: 198. In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 99% identity to any of SEQ ID NOs: 198-6,preferably SEQ ID NO: 198. In some embodiments, the polypeptide comprises or consists ofthe amino acid sequence of any of SEQ ID NOs: 198-6, preferably SEQ ID NO: 198.The polypeptide of the present invention may have a molecular weight of at least 30 kDa, atleast 40 kDa, at least 50 kDa, at least 60 kDa, at least 70 kDa, or at least 80 kDa. In someembodiments, the polypeptide has a molecular weight of from 30 kDa to 1000 kDa, from 40kDa to 1000 kDa, from 50 kDa to 1000 kDa, from 60 kDa to 1000 kDa, from 70 kDa to 1000kDa, or from 80 kDa to 1000 kDa. The polypeptide of the invention may be capable offorming a lyotropic liquid crystal mesophase. The polypeptide of the invention may be soluble at a concentration of at least 20 mg / ml, at least 30 mg / ml, at least 40 mg / ml, at least 50 mg / ml, at least 60 mg / ml, at least 70 mg / ml, at least 80 mg / ml, at least 90 mg / ml, or atleast 100 mg / ml. The polypeptide of the invention may be capable of being expressed by acell or a cell-free transcription and translation system.In another aspect, the present invention provides a composition comprising the polypeptideof the present invention. In some embodiments, the composition comprises the polypeptideat a concentration of at least 20 mg / ml, at least 30 mg / ml, at least 40 mg / ml, at least 50 mg / ml, at least 60 mg / ml, at least 70 mg / ml, at least 80 mg / ml, at least 90 mg / ml, or at least100 mg / ml. In some embodiments, the polypeptide is not denatured. In some embodiments,the composition comprises a solvent.In another aspect, the present invention provides a polynucleotide encoding the betasolenoid fold of the invention, the N-terminal capping sequence of the invention, the C-terminal capping sequence of the invention, the beta solenoid domain of the invention, or thepolypeptide of the invention.In another aspect, the present invention provides a vector comprising the polynucleotide ofthe invention.In another aspect, the present invention provides a cell comprising the polynucleotide of theinvention or the vector of the invention.In another aspect, the present invention provides a fibre comprising the polypeptide of theinvention. The fibre may be produced via a wet-spinning method.The fibre may have an average diameter of from 100 nm to 100 µm, from 500 nm to 50µm, from 1 µm to 40 µm, from 2.5 µm to 35 µm, from 5 µm to 30 µm, from 7.5 µm to 25 µm, or from 10 µm to 20 µm.The fibre may have a Young’s modulus of at least 0.5 GPa, at least 1.0 GPa, at least 2 GPa,at least 5.0 GPa, at least 10.0 GPa, at least 15.0 GPa, at least 20.0 GPa, at least 25.0 GPa,at least 30.0GPa, at least 35.0 GPa, at least 40.0 GPa, at least 50.0 GPa, at least 60.0 GPa,at least 70.0 GPa, at least 75.0 GPa, at least 80.0 GPa, at least 90.0 GPa, at least 100.0GPa, at least 125 GPa, at least 150 GPa, at least 175 GPa, or at least 200 GPa. The fibre may have an engineered strength of: at least 0.1 GPa, at least 0.2 GPa, at least 0.3 GPa, at least 0.4 GPa, at least 0.5 GPa, at least 0.6 GPa, at least 0.7 GPa, at least 0.8 GPa, at least 0.9 GPa, at least 1.0 GPa, at least 1.1 GPa, at least 1.2 GPa, at least 1.3 GPa, at least 1.4 GPa, at least 1.5 GPa, at least 1.6 GPa, at least 1.7 GPa, at least 1.8 GPa, at least 1.9 GPa, at least 2.0 GPa, at least 2.1 GPa, at least 2.2 GPa, at least 2.3 GPa, at least 2.4 GPa, at least 2.5 GPa, at least 2.6 GPa, at least 2.7 GPa, at least 2.8 GPa, at least 2.9 GPa, at least 3.0 GPa. The fibre may have a strain to failure of at least 2%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 90%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, or at least 300%. The fibre may have a toughness of at least 10 J / g, at least 20 J / g, at least 40 J / g, at least 60 J / g, at least 80 J / g, at least 100 J / g, at least 120 J / g, at least 140 J / g, at least 160 J / g, at least 180 J / g, at least 200 J / g, at least 250 J / g, at least 300 J / g, at least 350 J / g, at least 400 J / g, at least 450 J / g, at least 500 J / g, at least 550 J / g, at least 600 J / g, at least 650 J / g, at least 700 J / g, at least 750 J / g, at least 800 J / g, at least 850 J / g, at least 900 J / g, at least 950 J / g, at least 1000 J / g.In another aspect, the present invention provides yarn comprising the polypeptide accordingto the present invention or the fibre according to the present invention.In another aspect, the present invention provides a textile comprising the polypeptideaccording to the present invention, the fibre according to the present invention, or the yarn according to the present invention.In another aspect, the present invention provides use of the polypeptide according to thepresent invention, the fibre according to the present invention, the yarn according thepresent invention, or the textile according to the present invention, in the production of a textile product, wherein the textile product is selected from sportswear; materials for blast containment; materials for blade containment; textiles for parachutes; ropes; textiles for clothing; textiles for shoes; general medical textiles; wound dressings; resorbable and non- resorbable surgical sutures; resorbable and non-resorbable stents; guide-wires for surgery; biocompatible coatings for implanted medical devices; surgical meshes; and scaffolds for 3D tissue engineering. In another aspect, the present invention provides a textile product comprising thepolypeptide according to the present invention, the fibre according to the present invention,the yarn according the present invention, or the textile according to the present invention,wherein the textile product is selected from sportswear; materials for blast containment; materials for blade containment; textiles for parachutes; ropes; textiles for clothing; textiles for shoes; general medical textiles; wound dressings; resorbable and non-resorbable surgical sutures; resorbable and non-resorbable stents; guide-wires for surgery; biocompatible coatings for implanted medical devices; surgical meshes; and scaffolds for 3D tissue engineering. DESCRIPTION OF DRAWINGSFigure 1 – Example microscopy images for protein-based fibres(A) Example microscopy images. (B) Example birefringence images. (C) Example cross-section images.Figure 2 – Tensile testing results(A) Tensile testing results for several protein-based fibres tested. (B) Tensile testing resultsfor c_18 and l6 constructs.Figure 3 – Toughness resultsToughness results for all protein-based fibres tested. DETAILED DESCRIPTION Various preferred features and embodiments of the present invention will now be describedby way of non-limiting examples. This disclosure is not limited by the exemplary methodsand materials disclosed herein, and any methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of this disclosure. The skilled person will understand that they can combine all features of the invention disclosed herein without departing from the scope of the invention as disclosed. It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes", "containing", or "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or steps. The terms "comprising", "comprises" and "comprised of" also include the term "consisting of". Unless otherwise indicated, amino acid sequences are written left to right in amino tocarboxy orientation, respectively. Numeric ranges are inclusive of the numbers defining therange. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that such publications constitute prior art to the claims appended hereto. All publications mentioned in the specification are herein incorporated by reference. Beta solenoid foldsAs used herein, a “beta solenoid fold” may refer to a protein fold comprising or consisting ofrepeating beta strands subunits arranged in antiparallel fashion. Example of beta solenoid folds include beta-rolls and beta-helices (see e.g. Kajava, A.V. and Steven, A.C., 2006.Advances in protein chemistry, 73, pp.55-96). The terms “beta solenoid fold”, “beta solenoidstructure” and “beta solenoid sequence” may be used herein interchangeably.Beta solenoid consensus motifsSolenoid protein domains are a highly modular type of protein domain and typically consistof a chain of nearly identical folds, which may be referred to as a “consensus motif” or“tandem repeat”.Suitably, a beta solenoid fold may be defined by the presence of at least 4 units of aconsensus motif. Each unit may conform to a particular consensus motif, but each of the atleast four units may have a different sequence. Any suitable consensus motif may be usedto generate the beta solenoid folds (see e.g. MacDonald, J.T., et al., 2016. Proceedings ofthe National Academy of Sciences, 113(37), pp.10346-10351).Examples of suitable consensus sequences are provided below. In some embodiments, thebeta solenoid consensus motif is selected from any of SEQ ID NOs: 1 to 5. In someembodiments, the beta solenoid consensus motif is selected from any of SEQ ID NOs: 1 to5. In some embodiments, the beta solenoid consensus motif is SEQ ID NO: 1.In some embodiments, a beta solenoid fold comprises or consists of any one or more of thefollowing consensus sequences. In preferred embodiments, each unit within a beta solenoidfold conforms to the same consensus sequence.In some embodiments, the beta solenoid consensus motif is SEQ ID NO: 1.AXXXX wherein X is any amino acid, wherein X is L or F, wherein X is any amino acid, and wherein X is any amino acid Example beta solenoid consensus motif 1 (SEQ ID NO: 1)In some embodiments, X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T. In some embodiments, X1is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X2 is L or F. In some embodiments, X2 is L.In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y. In someembodiments, X3is S, E, R, T, D, H, Q, K, N, or C.In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C. In some embodiments,X4is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T, preferably X1 is D, N,I, S, E, K, L, R, or V, more preferably, X1is D or N; (b) X2is L or F, preferably X2is L; (c) X3is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y, preferably X3is S, E, R, T, D, H, Q, K, N, or C; and (d) X4is G, E, Q, K, R, A, D, H, N, Y, S, I, or C, preferably X4is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1is D, N, I, S, E, K, L, R, or V; (b) X2is L or F; (c) X3is S, E, R, T, D, H, Q, K, N, or C; and (d) X4is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D or N; (b) X2 is L; (c) X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid consensus motif is SEQ ID NO: 2.AXXXX wherein X is D,N,I,S,E,K,L,R,V,A,C,M or T, wherein X is L or F, wherein X is S,E,R,T,D,H,Q,K,N,C,A,F,G,I,V,W or Y, and wherein X is G,E,Q,K,R,A,D,H,N,Y,S,I or C Example beta solenoid consensus motif 2 (SEQ ID NO: 2)In some embodiments, X1 is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X2 is L. In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, or C. In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D or N; (b) X2 is L; (c) X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid consensus motif is SEQ ID NO: 3.AXLXX wherein X is any amino acid, wherein X is any amino acid, and wherein X is any amino acid Example beta solenoid consensus motif 3 (SEQ ID NO: 3)In some embodiments, X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T. In some embodiments, X1is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y. In someembodiments, X3 is S, E, R, T, D, H, Q, K, N, or C.In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C. In some embodiments,X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T, preferably X1 is D, N,I, S, E, K, L, R, or V, more preferably, X1 is D or N; (b) X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y, preferably X3 is S, E, R, T, D, H, Q, K, N, or C; and (c) X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C, preferably X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, or V; (b) X3 is S, E, R, T, D, H, Q, K, N, or C; and (c) X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D or N; (b) X3 is S, E, R, T, D, H, Q, K, N, or C; and (c) X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid consensus motif is SEQ ID NO: 4.AXLXX wherein X is D,N,I,S,E,K,L,R,V,A,C,M or T, wherein X is S,E,R,T,D,H,Q,K,N,C,A,F,G,I,V,W or Y, and wherein X is G,E,Q,K,R,A,D,H,N,Y,S,I or C Example beta solenoid consensus motif 4 (SEQ ID NO: 4)In some embodiments, X1 is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X3is S, E, R, T, D, H, Q, K, N, or C. In some embodiments, X4is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1is D or N; (c) X3is S, E, R, T, D, H, Q, K, N, or C; and (d) X4is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid consensus motif is SEQ ID NO: 5.A(N / D)LXX wherein X is S,E,R,T,D,H,Q,K,N,C, and wherein X is any amino acidExample beta solenoid consensus motif 5 (SEQ ID NO: 5)In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C. In some embodiments,X4is G, E, Q, K, R, A, D, H, N, or Y.A beta solenoid fold may have a cross-section that allows for a degree of tessellation orefficient packing. In some embodiments, the consensus motif of the units of a beta solenoidfold is selected such that a tesselatable cross-section is formed. In some embodiments, theconsensus motif forms a square cross-section. A beta solenoid fold which comprises orconsists of units that conform to the consensus motif of SEQ ID NOs: 1-5 may generate abeta solenoid fold with a square or approximately square cross-section. The number of units of the consensus motif may be varied. For example, the number of unitsof the consensus motif may be selected to achieve the desired aspect ratio of the betasolenoid fold. Units of the consensus motif may be arranged consecutively (i.e. tandemly),wherein one or more of the units of the consensus motif follows directly on from a first consensus motif. However, the units of the consensus motif may also comprise additional sequences between the units. Preferably, the units of the consensus motif are arranged consecutively.In some embodiments, a beta solenoid fold comprises or consists of at least 4 units, at least5 units, at least 6 units, at least 7 units, at least 8 units, at least 9 units, at least 10 units, at least 11 units, at least 12 units, at least 13 units, at least 14 units, at least 15 units, at least 16 units, at least 17 units, at least 18 units, at least 19 units, at least 20 units, at least 21 units, at least 22 units, at least 23 units, at least 24 units, at least 25 units, at least 26 units, at least 27 units, at least 28 units, at least 29 units, at least 30 units, at least 40 units, at least 50 units, at least 60 units, at least 70 units, at least 80 units, at least 90 units, at least 100units, or at least 200 units of a consensus motif.In another embodiment, a beta solenoid fold comprises or consists of less than 3000 units,less than 2000 units, less than 1000 units, less than 500 units, less than 400 units, less than 300 units, less than 200 units, less than 100 units, less than 90 units, less than 80 units, less than 70 units, less than 60 units, less than 50 units, less than 40 units, less than 30 units, less than 29 units, less than 28 units, less than 27 units, less than 26 units, less than 25 units, less than 24 units, less than 23 units, less than 22 units, less than 21 units, less than 20 units, less than 19 units, less than 18 units, less than 17 units, less than 16 units, less than 15 units, less than 14 units, less than 13 units, less than 12 units, less than 11 units, less than 10 units, less than 9 units, less than 8 units, less than 7 units, or less than 6 unitsof a consensus motif.In some embodiments, a beta solenoid fold comprises or consists of from 4 to 3000, from 5to 2800, from 6 to 2600, from 7 to 2400, from 8 to 2200, from 9 to 2000, from 10 to 1800,from 11 to 1600, from 12 to 1400, from 13 to 1200, from 14 to 1000, from 15 to 800, from 16to 600, from 17 to 500, from 18 to 400, from 19 to 300, from 20 to 250, from 20 to 200, from20 to 150, from 20 to 100, from 20 to 95, from 20 to 90, from 20 to 85, from 20 to 80, from 20to 75, from 20 to 70, from 20 to 65, from 20 to 60, from 20 to 55, from 20 to 50, from 20 to45, from 20 to 40, from 20 to 35, or from 20 to 30 units of a consensus motif.Beta solenoid consensus sequencesExamples of consensus beta solenoid folds are provided in SEQ ID NOs: 6 to 10. In someembodiments, a beta solenoid fold comprises or consists of the amino acid sequence of anyof SEQ ID NOs: 6 to 10. In some embodiments, a beta solenoid fold comprises or consists ofthe amino acid sequence of SEQ ID NO: 6.In some embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 6. (AXXXX) wherein X is any amino acid, wherein X is L or F, wherein X is any amino acid, wherein X is any amino acid, and wherein n is from 25 to 30, preferably 26 to 28, more preferably 27 Example consensus beta solenoid fold 1 (SEQ ID NO: 6)In some embodiments, X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T. In some embodiments, X1is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N. In some embodiments, X2is L. In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y. In someembodiments, X3is S, E, R, T, D, H, Q, K, N, or C. In some embodiments, X4is G, E, Q, K,R, A, D, H, N, Y, S, I, or C. In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T, preferably X1 is D, N,I, S, E, K, L, R, or V, more preferably, X1is D or N; (b) X2is L or F, preferably X2is L; (c) X3is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y, preferably X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C, preferably X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1is D, N, I, S, E, K, L, R, or V; (b) X2is L or F; (c) X3is S, E, R, T, D, H, Q, K, N, or C; and (d) X4is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1is D or N; (b) X2is L; (c) X3is S, E, R, T, D, H, Q, K, N, or C; and (d) X4is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 7. and wherein n is from 25 to 30, preferably 26 to 28, more preferably 27 Example consensus beta solenoid fold 2 (SEQ ID NO: 7)In some embodiments, X1 is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X2 is L. In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, or C. In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D or N; (b) X2 is L; (c) X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 8. (AXLXX) wherein X is any amino acid, wherein X is any amino acid, wherein X is any amino acid, and wherein n is from 25 to 30, preferably 26 to 28, more preferably 27 Example consensus beta solenoid fold 3 (SEQ ID NO: 8)In some embodiments, X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T. In some embodiments, X1is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y. In someembodiments, X3is S, E, R, T, D, H, Q, K, N, or C.In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C. In some embodiments,X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T, preferably X1 is D, N,I, S, E, K, L, R, or V, more preferably, X1 is D or N; (b) X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y, preferably X3 is S, E, R, T, D, H, Q, K, N, or C; and (c) X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C, preferably X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, or V; (b) X3 is S, E, R, T, D, H, Q, K, N, or C; and (c) X4is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1is D or N; (b) X3is S, E, R, T, D, H, Q, K, N, or C; and (c) X4is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 9. (AXLXX) wherein X is D,N,I,S,E,K,L,R,V,A,C,M or T, wherein X is S,E,R,T,D,H,Q,K,N,C,A,F,G,I,V,W or Y, wherein X is G,E,Q,K,R,A,D,H,N,Y,S,I or C, and wherein n is from 25 to 30, preferably 26 to 28, more preferably 27 Example consensus beta solenoid fold 4 (SEQ ID NO: 9)In some embodiments, X1 is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, or C. In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D or N; (c) X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 10. (A(N / D)LXX) wherein X is S,E,R,T,D,H,Q,K,N,C, wherein X is any amino acid, and wherein n is from 25 to 30, preferably 26 to 28, more preferably 27 Example consensus beta solenoid fold 5 (SEQ ID NO: 10)In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C. In some embodiments,X4 is G, E, Q, K, R, A, D, H, N, or Y. Example beta solenoid foldsExample beta solenoid folds are provided in SEQ ID NOs: 11 to 36.In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ IDNOs: 11 to 36, preferably wherein the beta solenoid fold has the consensus sequence ofSEQ ID NO: 6.In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ IDNOs: 11 to 36, and 27 units of SEQ ID NO: 1.In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 95% identity to any of SEQ ID NOs: 11 to 36. In someembodiments, the beta solenoid fold comprises or consists of an amino acid sequencehaving at least 98% identity to any of SEQ ID NOs: 11 to 36. In some embodiments, the betasolenoid fold comprises or consists of an amino acid sequence having at least 99% identityto any of SEQ ID NOs: 11 to 36. In some embodiments, the beta solenoid fold comprises orconsists of an amino acid sequence having 100% identity to any of SEQ ID NOs: 11 to 36. Insome embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of any of SEQ ID NOs: 11 to 36.In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ IDNOs: 23 to 36, preferably wherein the beta solenoid fold has the consensus sequence ofSEQ ID NO: 6. In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ IDNOs: 23 to 36, and 27 units of SEQ ID NO: 1.In some embodiments, the beta solenoid fold comprises or consists of an amino acidsequence having at least 95% identity to any of SEQ ID NOs: 23 to 36. In someembodiments, the beta solenoid fold comprises or consists of an amino acid sequencehaving at least 98% identity to any of SEQ ID NOs: 23 to 36. In some embodiments, the betasolenoid fold comprises or consists of an amino acid sequence having at least 99% identityto any of SEQ ID NOs: 23 to 36. In some embodiments, the beta solenoid fold comprises orconsists of an amino acid sequence having 100% identity to any of SEQ ID NOs: 23 to 36. Insome embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of any of SEQ ID NOs: 23 to 36. In some preferred embodiments, the beta solenoid fold comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 11-17, preferably wherein the beta solenoid fold has the consensus sequence ofSEQ ID NO: 6. In some preferred embodiments, the beta solenoid fold comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 11-17 and 27 units of SEQ ID NO: 1.In some preferred embodiments, the beta solenoid fold comprises or consists of an aminoacid sequence having at least 95% identity to any of SEQ ID NOs: 11-17. In some preferredembodiments, the beta solenoid fold comprises or consists of an amino acid sequencehaving at least 98% identity to any of SEQ ID NOs: 11-17. In some preferred embodiments,the beta solenoid fold comprises or consists of an amino acid sequence having at least 99%identity to any of SEQ ID NOs: 11-17. In some preferred embodiments, the beta solenoidfold comprises or consists of an amino acid sequence having 100% identity to any of SEQ IDNOs: 11-17. In some preferred embodiments, the beta solenoid fold comprises or consists ofthe amino acid sequence of any of SEQ ID NOs: 11-17.In some preferred embodiments, the beta solenoid fold comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 11, preferably wherein the beta solenoid fold has the consensus sequence of SEQ IDNO: 6.In some preferred embodiments, the beta solenoid fold comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 11 and 27 units of SEQ ID NO: 1.In some preferred embodiments, the beta solenoid fold comprises or consists of an aminoacid sequence having at least 95% identity to SEQ ID NO: 11. In some preferredembodiments, the beta solenoid fold comprises or consists of an amino acid sequencehaving at least 98% identity to SEQ ID NO: 11. In some preferred embodiments, the betasolenoid fold comprises or consists of an amino acid sequence having at least 99% identityto SEQ ID NO: 11. In some preferred embodiments, the beta solenoid fold comprises orconsists of an amino acid sequence having 100% identity to SEQ ID NO: 11. In somepreferred embodiments, the beta solenoid fold comprises or consists of the amino acidsequence of SEQ ID NO: 11.Capping sequencesAs used herein, “capping sequences” may be sequences provided at the ends of a betasolenoid fold to prevent the beta solenoid fold from aggregating end-to-end with other betasolenoid folds.The skilled person is able to design capping sequences and there are a number of differentways in which this can be achieved. For example, a terminal repeat similar to the consensussequence of the units of the beta solenoid fold may be used, but in which the solventexposed residues that would normally be buried are instead mutated to polar or charged residues, which is considered to help in shielding the hydrophobic core.Another approach is to disrupt the normal hydrogen bonding backbone pattern of theterminal repeat by adding a proline residue or forming a beta-bulge. Yet a further approachis to design the sequence of the beta solenoid fold so that part of the polypeptide chain foldsover and covers the end. For example, the capping sequences may form alpha heliceswhich cover the ends of the beta-helices. Such capping sequences can be found in nature ordesigned de novo by, for example, redesigning natural sequences using computationalprotein design methods. In preferred embodiments, a capping sequence comprises orconsists of one or more alpha helix. N-terminal capping sequencesAs used herein, an “N-terminal capping sequence” or “N-terminal capping domain” may be asequence suitable for capping the N-terminus of a beta solenoid fold. An example of aconsensus N-terminal capping sequence is provided by SEQ ID NO: 37.XMXXXXILXXYXXGXXXFXXIXLXXXXLXX wherein X is any amino acid, and wherein X is I or A Example consensus N-terminal capping sequence (SEQ ID NO: 37)In some embodiments, an N-terminal capping sequence comprises or consists of the aminoacid sequence of SEQ ID NO: 37. Example N-terminal capping sequences are provided inSEQ ID NOs: 38 to 43.In some embodiments, the N-terminal capping sequence comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 38 to 43, preferably wherein the N-terminal capping sequence has the consensussequence of SEQ ID NO: 37.In some embodiments, the N-terminal capping sequence comprises or consists of an aminoacid sequence having at least 93% identity to any of SEQ ID NOs: 38 to 43. In someembodiments, the N-terminal capping sequence comprises or consists of an amino acidsequence having at least 96% identity to any of SEQ ID NOs: 38 to 43. In someembodiments, the N-terminal capping sequence comprises or consists of the amino acidsequence of any of SEQ ID NOs: 38 to 43.In some embodiments, the N-terminal capping sequence comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 39 to 43, preferably wherein the N-terminal capping sequence has the consensussequence of SEQ ID NO: 37.In some embodiments, the N-terminal capping sequence comprises or consists of an aminoacid sequence having at least 93% identity to any of SEQ ID NOs: 39 to 43. In someembodiments, the N-terminal capping sequence comprises or consists of an amino acidsequence having at least 96% identity to any of SEQ ID NOs: 39 to 43. In someembodiments, the N-terminal capping sequence comprises or consists of the amino acidsequence of any of SEQ ID NOs: 39 to 43.Example N-terminal capping sequences In some preferred embodiments, the N-terminal capping sequence comprises or consists ofan amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity toSEQ ID NO: 38, preferably wherein the N-terminal capping sequence has the consensus sequence of SEQ ID NO: 37. In some preferred embodiments, the N-terminal capping sequence comprises or consists ofan amino acid sequence having at least 93% identity to SEQ ID NO: 38. In some preferredembodiments, the N-terminal capping sequence comprises or consists of an amino acidsequence having at least 96% identity to SEQ ID NO: 38. In some preferred embodiments,the N-terminal capping sequence comprises or consists of the amino acid sequence of SEQID NO: 38. C-terminal capping sequences As used herein, a “C-terminal capping sequence” or “C-terminal capping domain” may be asequence suitable for capping the C-terminus of a beta solenoid fold. An example of aconsensus C-terminal capping sequence is provided by SEQ ID NO: 44.AXXXXAXXXXAXXXXAXVXPVLWXXAXLXGAXXXXXXXXXXXXAXX wherein X is any amino acid, wherein X is T or L or F, wherein X is L or F, wherein X is L or F, wherein X is M or V, and wherein X is Y or F Example consensus C-terminal capping sequence (SEQ ID NO: 44)In some embodiments, a C-terminal capping sequence comprises or consists of the aminoacid sequence of SEQ ID NO: 37. Example C-terminal capping sequences are provided inSEQ ID NOs: 45 to 49.In some embodiments, the C-terminal capping sequence comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 45 to 49, preferably wherein the C-terminal capping sequence has the consensussequence of SEQ ID NO: 44. In some embodiments, the C-terminal capping sequence comprises or consists of an aminoacid sequence having at least 93% identity to any of SEQ ID NOs: 45 to 49. In someembodiments, the C-terminal capping sequence comprises or consists of an amino acidsequence having at least 96% identity to any of SEQ ID NOs: 45 to 49. In someembodiments, the C-terminal capping sequence comprises or consists of the amino acidsequence of any of SEQ ID NOs: 45 to 49.In some embodiments, the C-terminal capping sequence comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 46 to 49, preferably wherein the C-terminal capping sequence has the consensussequence of SEQ ID NO: 44. In some embodiments, the C-terminal capping sequence comprises or consists of an aminoacid sequence having at least 93% identity to any of SEQ ID NOs: 46 to 49. In someembodiments, the C-terminal capping sequence comprises or consists of an amino acidsequence having at least 96% identity to any of SEQ ID NOs: 46 to 49. In someembodiments, the C-terminal capping sequence comprises or consists of the amino acidsequence of any of SEQ ID NOs: 46 to 49. In some preferred embodiments, the C-terminal capping sequence comprises or consists ofan amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity toSEQ ID NO: 45, preferably wherein the C-terminal capping sequence has the consensus sequence of SEQ ID NO: 44. In some preferred embodiments, the C-terminal capping sequence comprises or consists ofan amino acid sequence having at least 93% identity to SEQ ID NO: 45. In some preferredembodiments, the C-terminal capping sequence comprises or consists of an amino acidsequence having at least 96% identity to SEQ ID NO: 45. In some preferred embodiments,the C-terminal capping sequence comprises or consists of the amino acid sequence of SEQID NO: 45. Beta solenoid domainsAs used herein, a “beta solenoid domain” may refer to a beta solenoid fold which is flankedby an N-terminal capping sequence and a C-terminal capping sequence. A “protein domain”may refer a compact, semi-independent unit, that make up structurally and functionallydistinct units (see e.g. Siddiqui and Barton 1995 Protein Science 4: 872-884). The terms“beta solenoid domain” and “capped beta solenoid domain” may be used herein interchangeably. Suitably, a beta solenoid domain is a linear solenoid which forms a rigid rod-shaped structure. As used herein, a “rod shape” may refer to a shape that is longer along one axis than in the transverse axis. Suitably, the cross-sectional shape and dimensions do not vary significantly along the length of the beta solenoid domain. For example, where the cross- section has an approximately square shape the three-dimensional shape of the beta solenoid domain may be considered to be approximately a square prism. A beta solenoid domain may have a longitudinal axis formed by the regular winding of the unit sequences and a transverse axis running perpendicular to the longitudinal axis. In some embodiments, the ratio of longitudinal length to transverse length of a beta solenoid domain (i.e. the aspect ratio) is at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least7:1, at least 8:1, at least 9:1, or at least 10:1. In some embodiments, a beta solenoid domainhas an aspect ratio of 100:1 or less, 50:1 or less, or 10:1 or less. In some embodiments, abeta solenoid domain has an aspect ratio of from 2:1 to 100:1, from 3:1 to 100:1, from 4:1 to100:1, from 5:1 to 100:1, from 6:1 to 100:1, from 7:1 to 100:1, from 8:1 to 100:1, from 9:1 to100:1, or from 10:1 to 100:1.In some embodiments, the length of a beta solenoid domain is from 5 to 4000 Angstroms in length, from 10 to 3000 Angstroms, from 15 to 2000 Angstroms, from 20 to 1000 Angstroms, from 25 to 500 Angstroms, from 30 to 250 Angstroms, from 35 to 200 Angstroms from 40 to 100 Angstroms, from 45 to 75 Angstroms, for example about 50 Angstroms. In someembodiments, the length of a beta solenoid domain is from 35 to 200 Angstroms.A beta solenoid domain may comprise hidden length. Hidden length may arise from a highdegree of coiling, such that when a longitudinal force is applied to the coil (i.e. when the force is applied parallel to an organised fibre comprising the beta solenoid domains), the coil extends so that the fully extended chain is many times longer than the original. A beta solenoid domain that comprises hidden length is considered to have a first compact conformation and a second extended conformation and is capable, upon application of alongitudinal force, of moving from the first conformation to the second conformation. The firstconformation may comprise a high degree of coiling. A beta solenoid domain may movebetween the first conformation and the second conformation when a defined force is applied parallel to the longitudinal axis of the polypeptide. In some embodiments, the length of thesecond conformation of a beta solenoid domain is at least 1.5 times longer, at least 2 timeslonger, at least 3 times longer, at least 4 times longer, at least 5 times longer, at least 10 times longer, at least 20 times longer, at least 30 times longer, at least 40 times longer, at least 50 times longer, or at least 100 times longer than the length of the first conformation of a beta solenoid domain.A beta solenoid domain may be capable of forming a lyotropic liquid crystal mesophasewhen expressed as monomers. The ability to form a lyotropic liquid crystal mesophase is associated with both the dimensions of the beta solenoid domains and the charge associated with the beta solenoid domain. Typically, “rod-like” domains are particularly suited to the formation of nematic liquid crystals, though other more ordered systems, such as smectics, or columnar phases, may occur. The aspect ratio and persistence length are related parameters that determine the concentration for the isotropic-nematic phase transition (see e.g. Escobedo, F.A. and de Pablo, J.J., 1997. The Journal of chemical physics, 106(23), pp.9858-9868). Any method may be used to determine whether a particular beta solenoid domain is capable of forming a lyotropic liquid crystal mesophase when expressed as monomers, including, for example, polarised optical microscopy (see e.g. Liquid Crystalline Polymers, CUP, 2006, A. M. Donald, A. H. Windle, S. Hanna).In some embodiments, a beta solenoid domain has a high net charge, for example a netcharge of at least +3 charge units, at least +5 charge units, at least +7 charge units, at least +10 charge units, at least +15 charge units, at least +20 charge units, at least +25 charge units, at least +30 charge units, at least +35 charge units, at least +40 charge units, at least +45 charge units, at least +50 charge units, at least +55 charge units, at least +60 charge units, at least +65 charge units, at least +70 charge units, at least +75 charge units, at least +80 charge units, at least +85 charge units, at least +90 charge units, at least +95 charge units, or at least +100 charge units, optionally at a pH range of 3 to 10 (e.g. pH 7). In someembodiments, a beta solenoid domain has a high negative net charge, for example a netcharge of less than -3 charge units, less than -5 charge units, less than -7 charge units, less than -10 charge units, less than -15 charge units, less than -20 charge units, less than -25 charge units, less than -30 charge units, less than -35 charge units, less than -40 charge units, less than -45 charge units, less than -50 charge units, less than -55 charge units, less than -60 charge units, less than -65 charge units, less than -70 charge units, less than -75 charge units, less than -80 charge units, less than -85 charge units, less than -90 charge units, less than -95 charge units, or less than -100 charge units, optionally at a pH range of 3 to 10 (e.g. pH 7).In some embodiments, a beta solenoid domain has a molecular weight of at least 15 kDa, atleast 20 kDa, at least 25 kDa, at least 30 kDa, at least 40 kDa, at least 50 kDa, at least 60 kDa, at least 70 kDa, at least 80 kDa, at least 90 kDa, at least 100 kDa, at least 120 kDa, at least 150 kDa, at least 200 kDa, at least 250 kDa, at least 300 kDa, optionally at least 350 kDa, at least 400 kDa, at least 450 kDa, or at least 500 kDa. In some embodiments, a betasolenoid domain has a molecular weight 500 kDa or less, 450 kDa or less, 400 kDa or less,300 kDa or less, 350 kDa or less, 250 kDa or less, 200 kDa or less, 150 kDa or less, 100 kDa or less, 90 kDa or less, 80 kDa or less, 70 kDa or less, 60 kDa or less, or 50 kDa orless. In some embodiments, a beta solenoid domain has a molecular weight from 15 kDa to500 kDa, from 15 kDa to 450 kDa, from 15 kDa to 400 kDa, from 15 kDa to 350 kDa, from 15 kDa to 300 kDa, from 15 kDa to 250 kDa, from 15 kDa to 200 kDa, from 15 kDa to 150 kDa, from 15 kDa to 100 kDa, or from 15 kDa to 50 kDa. A beta solenoid domain may comprise or consist of an N-terminal capping sequence (NCAP), a sequence that comprises at least 4 units of a beta solenoid consensus motif (UNITS), and a C-terminal cap sequence (CCAP). A beta solenoid domain may comprise orconsist of the following from N-terminus to C-terminus: NCAP – UNITSn – CCAP, wherein nis at least 4. In some embodiments, UNITS comprises or consists of the beta solenoid consensus motif ofany of SEQ ID NOs: 1 to 5. In some embodiments, UNITS comprises or consists of the betasolenoid consensus motif of SEQ ID NO: 1. In some embodiments, UNITSn comprises orconsists of the amino acid sequence of any of SEQ ID NOs: 6 to 10. In some embodiments,UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 6. In someembodiments, UNITSn comprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 11 to 36. In someembodiments, UNITSn comprises or consists of the amino acid sequence of any of SEQ IDNOs: 11 to 36. In some embodiments, UNITSn comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ ID NO:11. In some embodiments, UNITSn comprises or consists of the amino acid sequence ofSEQ ID NO: 11.In some embodiments, NCAP comprises of consists of the consensus sequence of SEQ IDNO: 37. In some embodiments, NCAP comprises or consists of an amino acid sequencehaving at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 38 to43. In some embodiments, NCAP comprises or consists of the amino acid sequence of anyof SEQ ID NOs: 38 to 43. In some embodiments, NCAP comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 38. In some embodiments, NCAP comprises or consists of the amino acid sequence ofSEQ ID NO: 38.In some embodiments, CCAP comprises of consists of the consensus sequence of SEQ IDNO: 44. In some embodiments, CCAP comprises or consists of an amino acid sequencehaving at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 45 to49. In some embodiments, CCAP comprises or consists of the amino acid sequence of anyof SEQ ID NOs: 45 to 49. In some embodiments, CCAP comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 45. In some embodiments, CCAP comprises or consists of the amino acid sequence ofSEQ ID NO: 45.In some embodiments, n is at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, atleast 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, at least 20, at least 21, at least 22, at least 23, at least 24, at least 25, at least 26, at least 27, at least 28, at least 29, at least 30, at least 40, at least 50, atleast 60, at least 70, at least 80, at least 90, at least 100, or at least 200. In someembodiments, n is less than 3000, less than 2000, less than 1000, less than 500, less than400, less than 300, less than 200, less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 29, less than 28, less than 27, less than 26, less than 25, less than 24, less than 23, less than 22, less than 21, less than 20, less than 19, less than 18, less than 17, less than 16, less than 15, less than 14,less than 13, less than 12, less than 11, less than 10, less than 9, less than 8, less than 7, orless than 6. In some embodiments, n is from 4 to 3000, from 5 to 2800, from 6 to 2600, from7 to 2400, from 8 to 2200, from 9 to 2000, from 10 to 1800, from 11 to 1600, from 12 to1400, from 13 to 1200, from 14 to 1000, from 15 to 800, from 16 to 600, from 17 to 500, from18 to 400, from 19 to 300, from 20 to 250, from 20 to 200, from 20 to 150, from 20 to 100,from 20 to 95, from 20 to 90, from 20 to 85, from 20 to 80, from 20 to 75, from 20 to 70, from20 to 65, from 20 to 60, from 20 to 55, from 20 to 50, from 20 to 45, from 20 to 40, from 20 to35, or from 20 to 30. In some embodiments, n is from 25 to 30, preferably 26 to 28, morepreferably 27. Example beta solenoid domain consensus sequenceAn example of a consensus beta solenoid domain having the sequence NCAP – UNITSn –CCAP is provided in SEQ ID NO: 50. XMXXXXILXXYXXGXXXFXXIXLXX(I / A)XLXX(AXXXX)AX(T / L / F)XXAX(L / F) XXAX(L / F)XXAXVXPVLWXXAXLXGAX(M / V)XXXXXXX(Y / F)XXAXX wherein X is any amino acid, wherein X is any amino acid, wherein X is L or F, wherein X is any amino acid, wherein Xis any amino acid, and wherein n is at least 4.Example NCAP – UNITS – CCAP sequence (SEQ ID NO: 50)In some embodiments, X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T. In some embodiments, X1is D, N, I, S, E, K, L, R, or V. In some embodiments, X1 is D or N.In some embodiments, X2 is L or F. In some embodiments, X2 is L.In some embodiments, X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y. In someembodiments, X3is S, E, R, T, D, H, Q, K, N, or C.In some embodiments, X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C. In some embodiments,X4is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T, preferably X1 is D, N,I, S, E, K, L, R, or V, more preferably, X1 is D or N; (b) X2 is L or F, preferably X2 is L; (c) X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y, preferably X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C, preferably X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D, N, I, S, E, K, L, R, or V; (b) X2 is L or F; (c) X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, or Y. In some embodiments: (a) X1 is D or N; (b) X2 is L; (c) X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, or Y.In some embodiments, n is at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, atleast 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, at least 20, at least 21, at least 24, at least 25, at least 26, at least 27, at least 28, at least 29, at least 30, at least 40, at least 50, at least 60, at least 70, atleast 80, at least 90, at least 100, or at least 200. In some embodiments, n is less than 3000,less than 2000, less than 1000, less than 500, less than 400, less than 300, less than 200, less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 29, less than 28, less than 27, less than 26, less than 25, less than 24, less than 23, less than 22, less than 21, less than 20, less than 19, less than 18, less than 17, less than 16, less than 15, less than 14, less than 13, less than 12, less than11, less than 10, less than 9, less than 8, less than 7, or less than 6. In some embodiments,n is from 4 to 3000, from 5 to 2800, from 6 to 2600, from 7 to 2400, from 8 to 2200, from 9 to2000, from 10 to 1800, from 11 to 1600, from 12 to 1400, from 13 to 1200, from 14 to 1000,from 15 to 800, from 16 to 600, from 17 to 500, from 18 to 400, from 19 to 300, from 20 to250, from 20 to 200, from 20 to 150, from 20 to 100, from 20 to 95, from 20 to 90, from 20 to85, from 20 to 80, from 20 to 75, from 20 to 70, from 20 to 65, from 20 to 60, from 20 to 55,from 20 to 50, from 20 to 45, from 20 to 40, from 20 to 35, or from 20 to 30. In someembodiments, n is from 25 to 30, preferably 26 to 28, more preferably 27.In some embodiments, (i) (a) X1 is D, N, I, S, E, K, L, R, V, A, C, M, or T, preferably X1 is D,N, I, S, E, K, L, R, or V, more preferably, X1 is D or N; (b) X2 is L or F, preferably X2 is L; (c) X3 is S, E, R, T, D, H, Q, K, N, C, A, F, G, I, V, W, or Y, preferably X3 is S, E, R, T, D, H, Q, K, N, or C; and (d) X4 is G, E, Q, K, R, A, D, H, N, Y, S, I, or C, preferably X4 is G, E, Q, K, R,A, D, H, N, or Y; and (ii) n is from 4 to 3000, from 5 to 2800, from 6 to 2600, from 7 to 2400,from 8 to 2200, from 9 to 2000, from 10 to 1800, from 11 to 1600, from 12 to 1400, from 13to 1200, from 14 to 1000, from 15 to 800, from 16 to 600, from 17 to 500, from 18 to 400,from 19 to 300, from 20 to 250, from 20 to 200, from 20 to 150, from 20 to 100, from 20 to95, from 20 to 90, from 20 to 85, from 20 to 80, from 20 to 75, from 20 to 70, from 20 to 65,from 20 to 60, from 20 to 55, from 20 to 50, from 20 to 45, from 20 to 40, from 20 to 35, orfrom 20 to 30, from 25 to 30, preferably 26 to 28, more preferably 27.In some embodiments, a beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequencesimilarity to SEQ ID NO: 50. In some embodiments, a beta solenoid domain comprises or consists of an amino acidsequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence similarity to SEQ ID NO: 50.In some embodiments, a beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to SEQID NO: 50. In some embodiments, a beta solenoid domain comprises or consists of an amino acidsequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% identity to SEQ ID NO: 50.In some embodiments, a beta solenoid domain comprises or consists of the sequence ofSEQ ID NO: 50.Example beta solenoid domain combinationsThe present invention provides a beta solenoid domain comprising any beta solenoid fold, N-terminal capping sequence, or C-terminal capping sequence described herein, or any combination thereof.In some embodiments: (1) UNITSn comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 11; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAP comprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (2) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 12; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (3) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 13; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 39; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 46; (4) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 14; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (5) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 15; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (6) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 16; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (7) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 17; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (8) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 18; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (9) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 19; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 47; (10) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 20; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 40; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (11) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 20; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (12) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 21; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (13) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 22; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (14) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 23; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 41; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (15) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 24; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 41; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (16) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 25; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (17) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 20; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 42; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (18) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 26; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (19) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 27; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (20) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 28; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 48; (21) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 29; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (22) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 30; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 43; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (23) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 31; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 43; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (24) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 32; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (25) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 19; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 49; (26) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 33; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (27) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 34; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; (28) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 35; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45; or (29) UNITSn comprises or consists of an amino acid sequence having atleast 90% sequence identity to SEQ ID NO: 36; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; and CCAPcomprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 45.In some embodiments: (1) UNITSn comprises or consists of the amino acid sequence ofSEQ ID NO: 11; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (2)UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 12; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (3) UNITSn comprises or consistsof the amino acid sequence of SEQ ID NO: 13; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 39; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 46; (4) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 14; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (5)UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 15; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (6) UNITSn comprises or consistsof the amino acid sequence of SEQ ID NO: 16; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (7) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 17; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (8)UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 18; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (9) UNITSn comprises or consistsof the amino acid sequence of SEQ ID NO: 19; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 47; (10) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 20; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:40; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (11)UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 20; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (12) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 21; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (13) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 22; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (14)UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 23; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 41; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (15) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 24; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 41; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (16) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 25; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (17)UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 20; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 42; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (18) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 26; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (19) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 27; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (20)UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 28; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 48; (21) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 29; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (22) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 30; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:43; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; (23)UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 31; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 43; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (24) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 32; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (25) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 19; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 49; (26)UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 33; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprisesor consists of the amino acid sequence of SEQ ID NO: 45; (27) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 34; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; (28) UNITSn comprises or consists of the amino acid sequenceof SEQ ID NO: 35; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; or (29)UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 36; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; and CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45. Example beta solenoid domain sequences are provided in SEQ ID NOs: 51 to 79.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence similarity toany of SEQ ID NOs: 51 to 79, preferably wherein the beta solenoid domain has theconsensus sequence of SEQ ID NO: 50. In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ IDNOs: 51 to 79, preferably wherein the beta solenoid domain has the consensus sequence ofSEQ ID NO: 50. In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence identity to any of SEQ ID NOs: 51 to 79.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 95% identity to any of SEQ ID NOs: 51 to 79. In someembodiments, the beta solenoid domain comprises or consists of an amino acid sequencehaving at least 98% identity to any of SEQ ID NOs: 51 to 79. In some embodiments, the betasolenoid domain comprises or consists of an amino acid sequence having at least 99%identity to any of SEQ ID NOs: 51 to 79. In some embodiments, the beta solenoid domaincomprises or consists of an amino acid sequence having 100% identity to any of SEQ IDNOs: 51 to 79. In some embodiments, the beta solenoid domain comprises or consists of theamino acid sequence of any of SEQ ID NOs: 51 to 79. In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence similarity toany of SEQ ID NOs: 51-57, preferably wherein the beta solenoid domain has the consensussequence of SEQ ID NO: 50.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ IDNOs: 51-57, preferably wherein the beta solenoid domain has the consensus sequence ofSEQ ID NO: 50. In some embodiments, a beta solenoid domain comprises or consists of an amino acidsequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence identity to any of SEQ ID NOs: 51-57.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 95% identity to any of SEQ ID NOs: 51-57. In some embodiments,the beta solenoid domain comprises or consists of an amino acid sequence having at least98% identity to any of SEQ ID NOs: 51-57. In some embodiments, the beta solenoid domaincomprises or consists of an amino acid sequence having at least 99% identity to any of SEQID NOs: 51-57. In some embodiments, the beta solenoid domain comprises or consists of anamino acid sequence having 100% identity to any of SEQ ID NOs: 51-57. In someembodiments, the beta solenoid domain comprises or consists of the amino acid sequenceof any of SEQ ID NOs: 51-57.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence similarity toSEQ ID NO: 51, preferably wherein the beta solenoid domain has the consensus sequenceof SEQ ID NO: 50.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ ID NO:51, preferably wherein the beta solenoid domain has the consensus sequence of SEQ IDNO: 50. In some embodiments, a beta solenoid domain comprises or consists of an amino acidsequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence identity to SEQ ID NO: 51.In some embodiments, the beta solenoid domain comprises or consists of an amino acidsequence having at least 95% identity to SEQ ID NO: 51. In some embodiments, the betasolenoid domain comprises or consists of an amino acid sequence having at least 98%identity to SEQ ID NO: 51. In some embodiments, the beta solenoid domain comprises orconsists of an amino acid sequence having at least 99% identity to SEQ ID NO: 51. In someembodiments, the beta solenoid domain comprises or consists of an amino acid sequencehaving 100% identity to SEQ ID NO: 51. In some embodiments, the beta solenoid domaincomprises or consists of the amino acid sequence of SEQ ID NO: 51.Linked beta solenoid domainsAs used herein, “linked beta solenoid domains” may refer to two beta solenoid domainswhich are linked by a linker sequence, preferably by a flexible linker. A linked beta solenoid domain sequence may comprise or consist of the following from N-terminus to C-terminus: [NCAP – UNITSn – CCAP] – LINK – [NCAP – UNITSn – CCAP],wherein [NCAP – UNITSn – CCAP] is a beta solenoid domain as defined herein. In preferredembodiments, the amino acid sequences of the beta solenoid domains are identical.In some embodiments, a linked beta solenoid domain sequence comprises two betasolenoid domains linked by a flexible linker, wherein each of the two beta solenoid domainsare described herein. Suitable beta solenoid domains are described in the section entitled“Beta solenoid domains”. Flexible linkers Flexible linkers are generally composed of small, non-polar (e.g. Gly) or polar (e.g. Ser) amino acids, which do not have bulky side chains. The small size of these amino acids provides flexibility, and allows for mobility of the connecting functional domains. The incorporation of Ser can maintain the stability of the linker in aqueous solutions by forming hydrogen bonds with the water molecules, and therefore reduces the unfavourable interaction between the linker and the protein moieties (see e.g. Chen, X., et al., 2013. Advanced drug delivery reviews, 65(10), pp.1357-1369).A flexible linker may comprise or consist of (G / A / S / T)x, wherein x is 3 or greater, for examplewherein x is from 3 to 50, from 3 to 40, or from 3 to 16, or wherein x is 4 or greater, for example wherein x is from 4 to 50, from 4 to 40, or from 4 to 16. A flexible linker maycomprise or consist of (G / A / S)x, wherein x is 3 or greater, for example wherein x is from 3 to50, from 3 to 40, or from 3 to 16, or wherein x is 4 or greater, for example wherein x is from 4 to 50, from 4 to 40, or from 4 to 16. Example flexible linkers include poly-glycine linkers, poly-alanine linkers, poly-serine linkers,glycine-rich linkers, alanine-rich linkers, serine-rich linkers, glycine- and alanine-rich linkers,glycine- and serine-rich linkers, and glycine / alanine / serine-rich linkers.A poly-glycine linker may consist of (Gly)x, wherein x is 3 or greater, for example wherein x is from 3 to 8, or 4 or greater, for example wherein x is from 4 to 8. A poly-alanine linker may consist of (Ala)x, wherein x is 3 or greater, for example wherein x is from 3 to 8, or 4 or greater, for example wherein x is from 4 to 8. A poly-serine linker may consist of (Ser)x, wherein x is 3 or greater, for example wherein x is from 3 to 8, or 4 or greater, for example wherein x is from 4 to 8. A glycine-rich linker may comprise 2 or more glycine residues, for example from 2 to 8 glycine residues, 3 or more glycine residues, for example from 3 to 8 glycine residues, or 4or more glycine residues, for example from 4 to 8 glycine residues. An alanine-rich linkermay comprise 2 or more alanine residues, for example from 2 to 8 alanine residues, 3 or more alanine residues, for example from 3 to 8 alanine residues, or 4 or more alanine residues, for example from 4 to 8 alanine residues. A serine-rich linker may comprise 2 or more serine residues, for example from 2 to 8 serine residues, 3 or more serine residues, for example from 3 to 8 serine residues, or 4 or more serine residues, for example from 4 to 8 serine residues.A glycine- and alanine-rich linker may comprise or consist of 3 or more total glycine / alanineresidues, for example from 3 to 8 total glycine / alanine residues, or 4 or more total glycine / alanine residues, for example from 4 to 8 total glycine / alanine residues. A glycine- and serine-rich linker may comprise or consist of 3 or more total glycine / serine residues, for example from 3 to 8 total glycine / serine residues, or 4 or more total glycine / serine residues,for example from 4 to 8 total glycine / serine residues. A glycine / alanine / serine-rich linker maycomprise or consist of 3 or more total glycine / alanine / serine residues, for example from 3 to 8 total glycine / alanine / serine residues, or 4 or more total glycine / alanine / serine residues, for example from 4 to 8 total glycine / alanine / serine residues. Example flexible linkers may comprise of consist of any of the following amino acid sequences: (Gly) (Gly) (SEQ ID NO: 80) (Gly) (SEQ ID NO: 81) (Gly) (SEQ ID NO: 82) (Gly) (SEQ ID NO: 83) (Gly) (SEQ ID NO: 84) (Ala) (Ala) (SEQ ID NO: 85) (Ala) (SEQ ID NO: 86) (Ala) (SEQ ID NO: 87) (Ala) (SEQ ID NO: 88) (Ala) (SEQ ID NO: 89) (Ser) (Ser) (SEQ ID NO: 90) (Ser) (SEQ ID NO: 91) (Ser) (SEQ ID NO: 92) (Ser) (SEQ ID NO: 93) (Ser) (SEQ ID NO: 94) (GS) (GS) (SEQ ID NO: 95) (GS) (SEQ ID NO: 96) (GS) (SEQ ID NO: 97) (AG) (AG) (SEQ ID NO: 98) (AG) (SEQ ID NO: 99) (AG) (SEQ ID NO: 100) (TG) (TG) (SEQ ID NO: 101) (TG) (SEQ ID NO: 102) (TG) (SEQ ID NO: 103) (GGS) (GGS) (SEQ ID NO: 104) (GGS) (SEQ ID NO: 105) (GGS) (SEQ ID NO: 106) (TGS) (TGS) (SEQ ID NO: 107) (TGS) (SEQ ID NO: 108) (TGS) (SEQ ID NO: 109) (GGGS) (SEQ ID NO: 110) (GGGS) (SEQ ID NO: 111) (GGGS) (SEQ ID NO: 112) (GGGS) (SEQ ID NO: 113) (GGGGS) (SEQ ID NO: 114) (GGGGS) (SEQ ID NO: 115) (GGGGS) (SEQ ID NO: 116) (GGGGS) (SEQ ID NO: 117) (GSSGSS) (SEQ ID NO: 118) (GSSGSS) (SEQ ID NO: 119) (GSSGSS) (SEQ ID NO: 120) (GSSGSS) (SEQ ID NO: 121) (GSGSGS) (SEQ ID NO: 122) (GSGSGS) (SEQ ID NO: 123) (GSGSGS) (SEQ ID NO: 124) (GSGSGS) (SEQ ID NO: 125) (GSSSSSS) (SEQ ID NO: 126) (GSSSSSS) (SEQ ID NO: 127) (GSSSSSS) (SEQ ID NO: 128) (GSSSSSS) (SEQ ID NO: 129) GGGSAGGGS (SEQ ID NO: 130) GGGSAAGGGS (SEQ ID NO: 131) GGGSAAAGGGS (SEQ ID NO: 132) GGGSAAAAGGGS (SEQ ID NO: 133) GGGSAAAAAGGGS (SEQ ID NO: 134) GGGSAAAAAAGGGS (SEQ ID NO: 135) GGGGSAGGGGS (SEQ ID NO: 136) GGGGSAAGGGGS (SEQ ID NO: 137) GGGGSAAAGGGGS (SEQ ID NO: 138) GGGGSAAAAGGGGS (SEQ ID NO: 139) GGGGSAAAAAGGGGS (SEQ ID NO: 140) GGGGSAAAAAAGGGGS (SEQ ID NO: 141)GGGGSLVPRGSGGGGS (SEQ ID NO: 142)GGGGSLVPRGSGGGG (SEQ ID NO: 143)GGSGGHMGSGG (SEQ ID NO: 144)GGQGGQGGSGGSAAAAAAAAGGSGGSGGQGGQ (SEQ ID NO: 145)In some embodiments, the flexible linker does not comprise or consist of the amino acid sequence of SEQ ID NO: 110. In some embodiments, the flexible linker does not compriseor consist of the amino acid sequence of SEQ ID NO: 110 or SEQ ID NO: 135.In some preferred embodiments, the flexible linker comprises or consists of SEQ ID NO:145. Polypeptides comprising a flexible linker comprising or consisting of SEQ ID NO: 145may have particularly advantageous properties (e.g. solubility, viscosity, spinnability, stretch, strength, and toughness). Example linked beta solenoid domainsExample linked beta solenoid domain sequences are provided in SEQ ID NOs: 146 to 174.In SEQ ID NOs: 146 to 174, x is typically from 3 to 50, from 3 to 40, or from 3 to 16. In someembodiments, x is from 4 to 50, from 4 to 40, or from 4 to 16. In SEQ ID NOs: 146 to 174,(N)x may be any flexible linker described herein. In some embodiments, (N)x comprises orconsist of an amino acid sequence selected from: (Gly)3, (Ala)3, (Ser)3, GS, AG, TG, GGS,TGS, or any of SEQ ID NOs: 80-145. In some embodiments, (N)x comprises or consists ofthe amino acid sequence of SEQ ID NO: 145. In some embodiments, (N)x consists of theamino acid sequence of SEQ ID NO: 145.In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence similarity toany of SEQ ID NOs: 146 to 174, preferably wherein each beta solenoid domain has theconsensus sequence of SEQ ID NO: 50.In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 146 to 174, preferably wherein each beta solenoid domain has the consensussequence of SEQ ID NO: 50. In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence identity to any of SEQ ID NOs: 146 to 174.In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 95% identity to any of SEQ ID NOs: 146 to 174. In someembodiments, the linked beta solenoid domains comprise or consist of an amino acidsequence having at least 98% identity to any of SEQ ID NOs: 146 to 174. In someembodiments, the linked beta solenoid domains comprise or consist of an amino acidsequence having at least 99% identity to any of SEQ ID NOs: 146 to 174. In someembodiments, the linked beta solenoid domains comprise or consist of an amino acidsequence having 100% identity to any of SEQ ID NOs: 146 to 174. In some embodiments,the linked beta solenoid domains comprise or consist of the amino acid sequence of any ofSEQ ID NOs: 146 to 174. In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence similarity toany of SEQ ID NOs: 146-152, preferably wherein each beta solenoid domain has theconsensus sequence of SEQ ID NO: 50. In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQID NOs: 146-152, preferably wherein each beta solenoid domain has the consensussequence of SEQ ID NO: 50. In some embodiments, the linked beta solenoid domains comprise or consist of an amino acid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence identity to any of SEQ ID NOs: 146-152. In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 95% identity to any of SEQ ID NOs: 146-152. In someembodiments, the linked beta solenoid domains comprise or consist of an amino acidsequence having at least 98% identity to any of SEQ ID NOs: 146-152. In someembodiments, the linked beta solenoid domains comprise or consist of an amino acidsequence having at least 99% identity to any of SEQ ID NOs: 146-152. In someembodiments, the linked beta solenoid domains comprise or consist of an amino acidsequence having 100% identity to any of SEQ ID NOs: 146-152. In some embodiments, thelinked beta solenoid domains comprise or consist of the amino acid sequence of any of SEQID NOs: 146-152.In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence similarity toSEQ ID NO: 146, preferably wherein each beta solenoid domain has the consensussequence of SEQ ID NO: 50.In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 146, preferably wherein each beta solenoid domain has the consensus sequence ofSEQ ID NO: 50. In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or100.0% sequence identity to SEQ ID NO: 146.In some embodiments, the linked beta solenoid domains comprise or consist of an aminoacid sequence having at least 95% identity to SEQ ID NO: 146. In some embodiments, thelinked beta solenoid domains comprise or consist of an amino acid sequence having at least98% identity to SEQ ID NO: 146. In some embodiments, the linked beta solenoid domainscomprise or consist of an amino acid sequence having at least 99% identity to SEQ ID NO:146. In some embodiments, the linked beta solenoid domains comprise or consist of anamino acid sequence having 100% identity to SEQ ID NO: 146. In some embodiments, thelinked beta solenoid domains comprise or consist of the amino acid sequence of SEQ IDNO: 146. PolypeptidesThe present invention provides a polypeptide comprising or consisting of any of the betasolenoid folds, N-terminal capping sequences, C-terminal capping sequences, or linked beta solenoid domain sequences described herein. The polypeptide may be an isolated polypeptide. The polypeptides of the present invention may have improved spinnability, allowing long fibres to be spun in a single wet-spinning run. The polypeptides of the invention may have a maximum length in a single wet-spinning run of at least 10m, at least 20m, at least 30m, atleast 40m, at least 50m, at least 60m, at least 70m, or at least 80m. The polypeptides of theinvention may have a maximum length in a single wet-spinning run of 200m or less, 150m or less, or 100m or less. The polypeptides of the invention may have a maximum length in a single wet-spinning run of from 10m to 200m, from 40m to 150m, or from 80m to 100m. The spinnability may be determined by any suitable method, for example as described in the examples.Polypeptides comprising at least two beta solenoid domainsThe present invention provides a polypeptide comprising at least two beta solenoid domains,wherein the at least two beta solenoid domains are linked by a flexible linker, and wherein the at least two beta solenoid domains are any described herein.A polypeptide comprising at least two beta solenoid domains may be referred to herein as a“concatemer of beta solenoid domains”. The polypeptide may comprise any number of betasolenoid domains, provided that the polypeptide comprises at least two beta solenoid domains that are linked by a flexible linker. In preferred embodiments, each of the betasolenoid domains comprised in the polypeptide are linked by a flexible linker.The polypeptide may comprise at least two beta solenoid domains, at least three betasolenoid domains, at least four beta solenoid domains, at least 5 beta solenoid domains, at least 6 beta solenoid domains, at least 7 beta solenoid domains, at least 8 beta solenoid domains, at least 9 beta solenoid domains, at least 10 beta solenoid domains, at least 11 beta solenoid domains, at least 12 beta solenoid domains, at least 13 beta solenoid domains, at least 14 beta solenoid domains, at least 15 beta solenoid domains, at least 16 beta solenoid domains, at least 17 beta solenoid domains, at least 18 beta solenoid domains, at least 19 beta solenoid domains, at least 20 beta solenoid domains, at least 21 beta solenoid domains, at least 22 beta solenoid domains, at least 23 beta solenoid domains, at least 24 beta solenoid domains, at least 25 beta solenoid domains, at least 26 beta solenoid domains, at least 27 beta solenoid domains, at least 28 beta solenoid domains, at least 29 beta solenoid domains, at least 30 beta solenoid domains, at least 35 beta solenoid domains, at least 40 beta solenoid domains, at least 45 beta solenoid domains, at least 50 beta solenoid domains, at least 55 beta solenoid domains, at least 60 beta solenoid domains, at least 65 beta solenoid domains, at least 70 beta solenoid domains, at least 75 beta solenoid domains, at least 80 beta solenoid domains, at least 85 beta solenoid domains, at least 90 beta solenoid domains, at least 95 beta solenoid domains, or at least 100 beta solenoid domains.The polypeptide may comprise 100 beta solenoid domains or fewer, 95 beta solenoiddomains or fewer, 90 beta solenoid domains or fewer, 85 beta solenoid domains or fewer, 80beta solenoid domains or fewer, 75 beta solenoid domains or fewer, 70 beta solenoiddomains or fewer, 65 beta solenoid domains or fewer, 60 beta solenoid domains or fewer, 55beta solenoid domains or fewer, 50 beta solenoid domains or fewer, 45 beta solenoiddomains or fewer, 40 beta solenoid domains or fewer, 35 beta solenoid domains or fewer, 30beta solenoid domains or fewer, 29 beta solenoid domains or fewer, 28 beta solenoiddomains or fewer, 27 beta solenoid domains or fewer, 26 beta solenoid domains or fewer, 25beta solenoid domains or fewer, 24 beta solenoid domains or fewer, 23 beta solenoiddomains or fewer, 22 beta solenoid domains or fewer, 21 beta solenoid domains or fewer, 20beta solenoid domains or fewer, 19 beta solenoid domains or fewer, 18 beta solenoiddomains or fewer, 17 beta solenoid domains or fewer, 16 beta solenoid domains or fewer, 15beta solenoid domains or fewer, 14 beta solenoid domains or fewer, 13 beta solenoiddomains or fewer, 12 beta solenoid domains or fewer, 11 beta solenoid domains or fewer, or10 beta solenoid domains or fewer.The polypeptide may comprise from 2 to 100 beta solenoid domains, from 2 to 95 betasolenoid domains, from 2 to 90 beta solenoid domains, from 2 to 85 beta solenoid domains, from 2 to 80 beta solenoid domains, from 2 to 75 beta solenoid domains, from 2 to 70 beta solenoid domains, from 2 to 65 beta solenoid domains, from 2 to 60 beta solenoid domains, from 2 to 55 beta solenoid domains, from 2 to 50 beta solenoid domains, from 2 to 45 beta solenoid domains, from 2 to 40 beta solenoid domains, from 2 to 35 beta solenoid domains, from 2 to 30 beta solenoid domains, from 2 to 29 beta solenoid domains, from 2 to 28 beta solenoid domains, from 2 to 27 beta solenoid domains, from 2 to 26 beta solenoid domains, from 2 to 25 beta solenoid domains, from 2 to 24 beta solenoid domains, from 2 to 23 beta solenoid domains, from 2 to 22 beta solenoid domains, from 2 to 21 beta solenoid domains, from 2 to 20 beta solenoid domains, from 2 to 19 beta solenoid domains, from 2 to 18 beta solenoid domains, from 2 to 17 beta solenoid domains, from 2 to 16 beta solenoid domains, from 2 to 15 beta solenoid domains, from 2 to 14 beta solenoid domains, from 2 to 13 beta solenoid domains, from 2 to 12 beta solenoid domains, from 2 to 11 beta solenoid domains, from 2 to 10 beta solenoid domains, from 3 to 10 beta solenoid domains, or from 4 to 10 beta solenoid domains.The polypeptide may have a molecular weight of at least 30 kDa, at least 40 kDa, at least 50kDa, at least 60 kDa, at least 70 kDa, at least 80 kDa, at least 90 kDa, at least 100 kDa, at least 120 kDa, at least 150 kDa, at least 200 kDa, at least 250 kDa, at least 300 kDa, optinally at least 350 kDa, at least 400 kDa, at least 450 kDa, at least 500 kDa, at least 600kDa, at least 650 kDa, at least 700 kDa, at least 800 kDa, at least 900 kDa, or at least 1000kDa. The polypeptide may have a molecular weight of 1000 kDa or less, 900 kDa or less,800 kDa or less, 700 kDa or less, 600 kDa or less, 500 kDa or less, 400 kDa or less, 300kDa or less, 200 kDa or less, or 100 kDa or less. The polypeptide may have a molecularweight of from 30 kDa to 1000 kDa, from 30 kDa to 900 kDa, from 30 kDa to 800 kDa, from30 kDa to 700 kDa, from 30 kDa to 600 kDa, from 30 kDa to 500 kDa, from 30 kDa to 400kDa, from 30 kDa to 300 kDa, from 30 kDa to 200 kDa, or from 30 kDa to 100 kDa.The polypeptide may have an aspect ratio of from 4:1 to 1000:1. In some embodiments, the polypeptide has an aspect ratio of at least 4:1, at least 6:1, at least 8:1, at least 10:1, at least 10:1, at least 50:1, at least 100:1, at least 200:1, at least 300:1, at least 400:1, at least 500:1, at least 600:1, at least 700:1, at least 800:1, at least 900:1, or at least 1000:1.The polypeptide may be capable of forming a lyotropic liquid crystal mesophase. The abilityto form a lyotropic liquid crystal mesophase is associated with both the dimensions of thepolypeptide and the charge associated with the polypeptide. Any method may be used todetermine whether the polypeptide is capable of forming a lyotropic liquid crystalmesophase, including, for example, polarised optical microscopy. Higher surface charge increases the effective diameter of the rod-like beta solenoids or polypeptide, adjusting the aspect ratio and volume fraction of the mesogens, and hence thephase diagram as a function of concentration. The charge units referred to herein areelementary charge units (e), which is the electric charge carried by a single proton (e), orequivalently, the magnitude of the electric charge carried by a single electron, which has charge -e. In some embodiments, the polypeptide has a high net charge, for example a net charge of at least +3 charge units, at least +5 charge units, at least +7 charge units, at least +10 charge units, at least +15 charge units, at least +20 charge units, at least +25 charge units, at least +30 charge units, at least +35 charge units, at least +40 charge units, at least +45 charge units, at least +50 charge units, at least +55 charge units, at least +60 charge units, at least +65 charge units, at least +70 charge units, at least +75 charge units, at least +80 charge units, at least +85 charge units, at least +90 charge units, at least +95 charge units, at least +100 charge units, at least +200 charge units, at least +300 charge units, at least +400 charge units, at least +500 charge units, at least +600 charge units, at least +700 charge units, at least +800 charge units, at least +900 charge units, at least +1000 charge units, at least +2000 charge units, at least +3000 charge units, at least +4000 charge units, at least +5000 charge units, at least +6000 charge units, at least +7000 charge units, at least +8000 charge units, at least +9000 charge units, or at least +10000 charge units, optionally at a pH range of 3 to 10 (e.g. pH 7). In some embodiments, the polypeptide has a high negative net charge, for example a net charge of less than -3 charge units, less than -5 charge units, less than -7 charge units, less than -10 charge units, less than -15 charge units, less than -20 charge units, less than -25 charge units, less than -30 charge units, less than -35 charge units, less than -40 charge units, less than -45 charge units, less than -50 charge units, less than -55 charge units, less than -60 charge units, less than -65 charge units, less than -70 charge units, less than -75 charge units, less than -80 charge units, less than -85 charge units, less than -90 charge units, less than -95 charge units, less than -100charge units, less than -200 charge units, less than -300 charge units, less than -400 chargeunits, less than -500 charge units, less than -600 charge units, less than -700 charge units, less than -800 charge units, less than -900 charge units, less than -1000 charge units, less than -2000 charge units, less than -3000 charge units, less than -4000 charge units, less than -5000 charge units, less than -6000 charge units, less than -7000 charge units, less than -8000 charge units, less than -9000 charge units, or less than -10000 charge units, optionally at a pH range of 3 to 10 (e.g. pH 7).The polypeptide may be soluble at high concentrations. In some embodiments, thepolypeptide is soluble at a concentration of at least 20 mg / ml, at least 30 mg / ml, at least 40mg / ml, at least 50 mg / ml, at least 60 mg / ml, at least 70 mg / ml, at least 80 mg / ml, at least 90 mg / ml, at least 100 mg / ml, at least 120 mg / ml, at least 130 mg / ml, at least 150 mg / ml, at least 170 mg / ml, at least 190 mg / ml, at least 200 mg / ml, at least 250 mg / ml, at least 300 mg / ml, at least 350 mg / ml, or at least 400 mg / ml.The polypeptide may be soluble in an aqueous solution. In some embodiments, thepolypeptide is soluble in at least any solvent selected from the group consisting of: a) abuffer selected from the group consisting of any one or more of: MES, Bis-tris methane, ADA, ACES, Bis-tris propane, PIPES, MOPSO, Cholamine chloride, MOPS, BES, TES, HEPES, DIPSO, MOBS, Acetamidoglycine, TAPSO, TEA, POPSO, HEPPSO, EPS, HEPPS, Tricine, Tris, Glycinamide, Glycylglycine, HEPBS, Bicine, TAPS, AMPB, CHES, AMP, AMPSO CAPSO, CAPS, CABS, Bicine, sodium citrate buffer, sodium bicarbonate buffer, phosphate buffer, borate buffer, optionally wherein the buffer comprises one or more salts, e.g. sodium chloride and / or potassium chloride, optionally wherein the buffer is at a pH range of 3 to 10, e.g. pH 7; b) an organic solvent, optionally HFIP.In some embodiments, the polypeptide is soluble at a concentration of at least 20 mg / ml, atleast 30 mg / ml, at least 40 mg / ml, at least 50 mg / ml, at least 60 mg / ml, at least 70 mg / ml, at least 80 mg / ml, at least 90 mg / ml, at least 100 mg / ml, at least 120 mg / ml, at least 130 mg / ml, at least 150 mg / ml, at least 170 mg / ml, at least 190 mg / ml, at least 200 mg / ml, atleast 250 mg / ml, at least 300 mg / ml, at least 350 mg / ml, or at least 400 mg / ml in any one ormore of: a) a buffer selected from the group consisting of any one or more of: MES, Bis-trismethane, ADA, ACES, Bis-tris propane, PIPES, MOPSO, Cholamine chloride, MOPS, BES, TES, HEPES, DIPSO, MOBS, Acetamidoglycine, TAPSO, TEA, POPSO, HEPPSO, EPS, HEPPS, Tricine, Tris, Glycinamide, Glycylglycine, HEPBS, Bicine, TAPS, AMPB, CHES, AMP, AMPSO CAPSO, CAPS, CABS, Bicine, sodium citrate buffer, sodium bicarbonate buffer, phosphate buffer, borate buffer, optionally wherein the buffer comprises one or more salts, e.g. sodium chloride and / or potassium chloride, optionally wherein the buffer is at a pH range of 3 to 10, e.g. pH 7; b) an organic solvent, optionally HFIP.In some embodiments, the polypeptide is not soluble in aqueous solution at a high saltconcentration (e.g. at high concentrations of ammonium sulfate or other salts from theHofmeister series known to “salt out” proteins).The polypeptide may be capable of being produced through biotechnological means, forexample through protein expression systems that involve the use of microbes. In someembodiments, the polypeptide is capable of being expressed by a cell or a cell-freetranscription and translation system. The cell may be any cell for example a cell that isgenerally used in commercial protein expression systems. The cell may be a prokaryotic cell,optionally a bacterial cell, for example an E. coli cell, a Bacillus subtilis cell, a Bacillusmegaterium cell, a Vibrio natriegens cell, or a Pseudomonas fluorescens cell. The cell mayalso be a eukaryotic cell, optionally a yeast cell, for example Pichia pastoris orSaccharomyces cerevisiae; or an insect cell, for example a baculovirus infected insect cell; or a mammalian cell, for example a baculovirus infected mammalian cell, a HEK293 cell, a HeLa cell, or CHO cells. Suitable expression systems will be known to the skilled person. The polypeptides of the present invention may also be expressed through cell-freeexpression systems, for example by using E. coli lysates or rabbit reticulocyte lysates.The polypeptide may be capable of being purified, for example by ion exchangechromatography.The polypeptide may have a melting temperature of 60oC or more. In some embodiments,the polypeptide has a melting temperature of 65oC or more, 70oC or more, 75oC or more, or 80oC or more. In some embodiments, the polypeptide has a melting temperature of 100oC orless, 95oC or less, 90oC or less, 85oC or less, or 80oC or less. In some embodiments, thepolypeptide has a melting temperature of from 60oC to 100oC, from 65oC to 95oC, or from 70oC to 90oC.In some embodiments, the at least two beta solenoid domains each comprise or consist ofunits that conform to the same consensus sequence. In some embodiments, the at least twobeta solenoid domains each have the same number of units of a consensus motif. In someembodiments, the amino acid sequences of the at least two beta solenoid domains areidentical. Tag sequences The polypeptides of the present invention may further comprise one or more tag sequences. The tag sequence may be at the N-terminus or C-terminus of the polypeptide.Tag sequences (also known as “tagging sequences”) are commonly used for purification orvisualisation of a protein, for example on a western blot or through fluorescence microscopy.Examples of useful tag sequences include, but are not limited to, Albumin-binding protein(ABP), Alkaline Phosphatase (AP), AU1 epitope, AU5 epitope, Bacteriophage T7 epitope(17- tag), Bacteriophage V5 epitope (V5-tag), Biotin-carboxy carrier protein (BCCP),Bluetongue virus tag (B-tag), Calmodulin binding peptide (CBP), Chloramphenicol Acetyl Transferase (CAT), Cellulose binding domain (CBP), Chitin binding domain (CBD), Choline- binding domain (CBD), Dihydrofolate reductase (DHFR), E2 epitope, FLAG epitope, Galactose-binding protein (GBP), Green fluorescent protein (GFP), Glu-Glu (EE-tag), Glutathione S-transferase (GST), Human influenza hemagglutinin (HA), HaloTag®, Histidine affinity tag (HAT), Horseradish Peroxidase (HRP), HSV epitope, Ketosteroid isomerase (KSI), KT3 epitope, LacZ, Luciferase, Maltose-binding protein (MBP), Myc epitope, NusA, PDZ domain, PDZ ligand, Polyarginine (Arg-tag), Polyaspartate (Asp-tag, Polycysteine (Cys-tag), Polyhistidine (His- tag), Polyphenylalanine (Phe-tag), Profinity eXact, Protein C S1-tag,S-tag, Streptavadin-binding peptide (SBP), Staphylococcal protein A (Protein A),Staphylococcal protein G (Protein G), Strep-tag, Streptavadin, Small Ubiquitin-like Modifier (SUMO), Tandem Affinity Purification (TAP), T7 epitope, Thioredoxin (Trx), TrpE, Ubiquitin,Universal (see e.g. Kimple, M.E., et al., 2013. Current protocols in protein science, 73(1),pp.9-9). In some embodiments, the tag sequence is a His-tag. A His-tag may comprise or consist of5-10 histidine residues, for example (His)6 (SEQ ID NO: 227). In some embodiments, the tagsequence is a Gly-His-tag (e.g. GHHHH (SEQ ID NO: 228), GHHHHHH (SEQ ID NO: 229),or GSSHHHHHH (SEQ ID NO: 230)).In some embodiments, the polypeptide comprises a tag sequence and a protease cleavagesite, e.g. at the N-terminus of the polypeptide. The protease cleavage site may be used tocleave the tag sequence once the polypeptide has been purified. In some embodiments, theprotease cleavage site is a thrombin cleavage site, e.g. LVPRGS (SEQ ID NO: 231), or aTEV protease site, e.g. ENLYFQS (SEQ ID NO: 232). In some embodiments, the proteasecleavage site is a thrombin cleavage site, e.g. SEQ ID NO: 231.In some embodiments, the polypeptide comprises a His-tag and a thrombin cleavage site.An example amino acid sequence comprising a His-tag and a thrombin cleavage site is provided in SEQ ID NO: 175. In some embodiments, the tag sequence comprises or consists of an amino acid sequence having at least 80%, at least 85%, at least 90%, or at least 95% sequence similarity to SEQ ID NO: 175. In some embodiments, the tag sequencecomprises or consists of an amino acid sequence having at least 80%, at least 85%, at least 90%, or at least 95% sequence identity to SEQ ID NO: 175. In some embodiments, the tag sequence comprises or consists the amino acid sequence of SEQ ID NO: 175. MGSSHHHHHHSSGLVPRGS Example His-tag and a thrombin cleavage site (SEQ ID NO: 175)Tail sequences The polypeptide may further comprise one or more tail sequences. Suitably, the one or more tail sequences are at the C-terminus of the polypeptide. As used herein, a “tail sequence” may refer to an optional hydrophilic sequence with aflexible structure, which can serve the purpose of increasing protein solubility and / or inhibiting crystallisation. Typically, tail sequences are from 1 to 10 amino acids in length (e.g.5 amino acids in length) and comprise from 1 to 10 amino acids (e.g. 3, 4, or 5 amino acids)selected from the group consisting of charged, polar, glycine and alanine residues. Exampletail sequences are provided in SEQ ID NOs: 176 to 197.Example tail sequence 1 KSDDG (SEQ ID NO: 176)Example tail sequence 2 KQTEG (SEQ ID NO: 177)Example tail sequence 3 KQTKG (SEQ ID NO: 178)Example tail sequence 4 QQTNG (SEQ ID NO: 179)Example tail sequence 5 KTTEG (SEQ ID NO: 180)Example tail sequence 6 QQDNG (SEQ ID NO: 181)Example tail sequence 7 QQDEG (SEQ ID NO: 182)Example tail sequence 8 QKDNG (SEQ ID NO: 183)Example tail sequence 9 KQDNG (SEQ ID NO: 184)Example tail sequence 10 QEDKG (SEQ ID NO: 185)Example tail sequence 11 RKTNG (SEQ ID NO: 186)Example tail sequence 12 KSTDG (SEQ ID NO: 187)Example tail sequence 13 QKDNG (SEQ ID NO: 188)Example tail sequence 14 QETRG (SEQ ID NO: 189)Example tail sequence 15 QQDKG (SEQ ID NO: 190)Example tail sequence 16 QSDDG (SEQ ID NO: 191)Example tail sequence 17 QEDKG (SEQ ID NO: 192)Example tail sequence 18 QSDDG (SEQ ID NO: 193)Example tail sequence 19 KEDRG (SEQ ID NO: 194)Example tail sequence 20 QSDDG (SEQ ID NO: 195)Example tail sequence 21 QSDDG (SEQ ID NO: 196)Example tail sequence 22 QQTNG (SEQ ID NO: 197) In some embodiments, a tail sequence comprises or consists of an amino acid sequencehaving at least 80% sequence similarity to any of SEQ ID NOs: 176 to 197. In someembodiments, a tail sequence comprises or consists of an amino acid sequence having atleast 80% sequence identity to any of SEQ ID NOs: 176 to 197. In some embodiments, a tailsequence comprises or consists of the amino acid sequence of any of SEQ ID NOs: 176 to197. In some embodiments, a tail sequence comprises or consists of an amino acid sequencehaving at least 80% sequence similarity to SEQ ID NO: 176. In some embodiments, a tailsequence comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176. In some embodiments, a tail sequence comprises or consists of the amino acid sequence of any of SEQ ID NO: 176. Example polypeptidesA polypeptide according to the present invention may comprise or consist of a combinationof all of, or any subset of, the following components: a tag sequence (TAG), an N-terminalcapping sequence (NCAP), a sequence that comprises at least 4 units of a beta solenoidconsensus motif (UNITS), a sequence linking the at least two beta solenoid domains (LINK),a C-terminal cap sequence (CCAP), and a tail sequence (TAIL).A polypeptide according to the present invention may comprise or consist of the followingfrom N-terminus to C-terminus: NCAP – UNITSn – [LINK – UNITSn]m-1 – CCAPTAG – NCAP – UNITSn – [LINK – UNITSn]m-1 – CCAPNCAP – UNITSn – [LINK – UNITSn]m-1 – CCAP – TAILTAG – NCAP – UNITSn – [LINK – UNITSn]m-1 – CCAP – TAILNCAP – UNITSn – [LINK – UNITSn]m-1 – CCAP – TAGNCAP – UNITSn – [LINK – UNITSn]m-1 – CCAP – TAIL – TAGNCAP – UNITSn – [LINK – UNITSn]m-1 – CCAP – TAG – TAILwherein m is at least 2, wherein n is at least 4, and wherein LINK is a flexible linker. In some embodiments, UNITS comprises or consists of the beta solenoid consensus motif ofany of SEQ ID NOs: 1 to 5. In some embodiments, UNITS comprises or consists of the beta solenoid consensus motif of SEQ ID NO: 1. In some embodiments, UNITSncomprises orconsists of the amino acid sequence of any of SEQ ID NOs: 6 to 10. In some embodiments,UNITSn comprises or consists of the amino acid sequence of SEQ ID NOs: 6. In someembodiments, UNITSncomprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 11 to 36. In someembodiments, UNITSn comprises or consists of the amino acid sequence of any of SEQ IDNOs: 11 to 36. In some embodiments, UNITSn comprises or consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ ID NO:11. In some embodiments, UNITSn comprises or consists of the amino acid sequence ofSEQ ID NO: 11.In some embodiments, NCAP comprises of consists of the consensus sequence of SEQ IDNO: 37. In some embodiments, NCAP comprises or consists of an amino acid sequencehaving at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 38 to43. In some embodiments, NCAP comprises or consists of the amino acid sequence of anyof SEQ ID NOs: 38 to 43. In some embodiments, NCAP comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 38. In some embodiments, NCAP comprises or consists of the amino acid sequence ofSEQ ID NO: 38.In some embodiments, CCAP comprises of consists of the consensus sequence of SEQ IDNO: 44. In some embodiments, CCAP comprises or consists of an amino acid sequencehaving at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 45 to49. In some embodiments, CCAP comprises or consists of the amino acid sequence of anyof SEQ ID NOs: 45 to 49. In some embodiments, CCAP comprises or consists of an aminoacid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%,at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ IDNO: 45. In some embodiments, CCAP comprises or consists of the amino acid sequence ofSEQ ID NO: 45.In some embodiments, n is at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, atleast 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, at least 20, at least 21, at least 22, at least 23, at least 24, at least 25, at least 26, at least 27, at least 28, at least 29, at least 30, at least 40, at least 50, atleast 60, at least 70, at least 80, at least 90, at least 100, or at least 200. In someembodiments, n is less than 3000, less than 2000, less than 1000, less than 500, less than400, less than 300, less than 200, less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 29, less than 28, less than 27, less than 26, less than 25, less than 24, less than 23, less than 22, less than 21, less than 20, less than 19, less than 18, less than 17, less than 16, less than 15, less than 14,less than 13, less than 12, less than 11, less than 10, less than 9, less than 8, less than 7, orless than 6. In some embodiments, n is from 4 to 3000, from 5 to 2800, from 6 to 2600, from7 to 2400, from 8 to 2200, from 9 to 2000, from 10 to 1800, from 11 to 1600, from 12 to1400, from 13 to 1200, from 14 to 1000, from 15 to 800, from 16 to 600, from 17 to 500, from18 to 400, from 19 to 300, from 20 to 250, from 20 to 200, from 20 to 150, from 20 to 100,from 20 to 95, from 20 to 90, from 20 to 85, from 20 to 80, from 20 to 75, from 20 to 70, from20 to 65, from 20 to 60, from 20 to 55, from 20 to 50, from 20 to 45, from 20 to 40, from 20 to35, or from 20 to 30. In some embodiments, n is from 25 to 30, preferably 26 to 28, morepreferably 27.In some embodiments, LINK comprises or consists of (G / A / S / T)x, wherein x is 3 or greater,for example wherein x is from 3 to 50, from 3 to 40, or from 3 to 16, or wherein x is 4 orgreater, for example wherein x is from 4 to 50, from 4 to 40, or from 4 to 16. In someembodiments, LINK comprises or consists of (G / A / S)x, wherein x is 3 or greater, for examplewherein x is from 3 to 50, from 3 to 40, or from 3 to 16, or wherein x is 4 or greater, forexample wherein x is from 4 to 50, from 4 to 40, or from 4 to 16. In some embodiments,LINK comprises or consists of the amino acid sequence of SEQ ID NO: 145. In someembodiments, LINK consists of the amino acid sequence of SEQ ID NO: 145. In some embodiments, TAG comprises or consists of an amino acid sequence having at least 80%, at least 85%, at least 90%, or at least 95% sequence identity to SEQ ID NO: 175. In some embodiments, TAG comprises or consists of the amino acid sequence of SEQ ID NO: 175. In some embodiments, TAIL comprises or consists of an amino acid sequence having atleast 80% sequence identity to any of SEQ ID NOs: 176 to 197. In some embodiments, TAILcomprises or consists of the amino acid sequence of any of SEQ ID NOs: 176 to 197.In some embodiments, m is at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, at least 20, at least 21, at least 22, at least 23, at least 24, at least 25, at least 26, at least 27, at least 28, at least 29, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, atleast 75, at least 80, at least 85, at least 90, at least 95, or at least 100. In someembodiments, m is 100 or less, 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 orless, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 orless, 29 or less, 28 or less, 27 or less, 26 or less, 25 or less, 24 or less, 23 or less, 22 orless, 21 or less, 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 orless, 13 or less, 12 or less, 11 or less, or less, 9 or less, or 8 or less. In some embodiments, m is from 2 to 100, from 2 to 95, from 2 to 90, from 2 to 85, from 2 to 80, from 2 to 75, from 2 to 70, from 2 to 65, from 2 to 60, from 2 to 55, from 2 to 50, from 2 to 45, from2 to 40, from 2 to 35, from 2 to 30, from 2 to 29, from 2 to 28, from 2 to 27, from 2 to 26, from2 to 25, from 2 to 24, from 2 to 23, from 2 to 22, from 2 to 21, from 2 to 20, from 2 to 19, from 2 to 18, from 2 to 17, from 2 to 16, from 2 to 15, from 2 to 14, from 2 to 13, from 2 to 12, from 2 to 11, from 2 to 10, from 2 to 9, from 2 to 8, from 3 to 8, or from 4 to 8. In some embodiments, m is 4. In some embodiments, (i) (a) UNITSncomprises or consists of an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identity to any of SEQ ID NOs: 11 to36, preferably SEQ ID NO: 11; (b) NCAP comprises of consists of the consensus sequenceof SEQ ID NO: 37, preferably NCAP comprises of consists of an amino acid sequencehaving at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to any ofSEQ ID NOs: 38 to 43, more preferably NCAP comprises of consists of an amino acidsequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identityto SEQ ID NO: 38; (c) CCAP comprises of consists of the consensus sequence of SEQ IDNO: 44, preferably CCAP comprises or consists of an amino acid sequence having at least90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to any of SEQ ID NOs: 45to 49, more preferably CCAP comprises or consists of an amino acid sequence having atleast 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to SEQ ID NO: 45; (d) TAG comprises or consists of an amino acid sequence having at least 80%, at least 85%, at least 90%, or at least 95% sequence identity to SEQ ID NO: 175, preferably TAG comprises or consists of the amino acid sequence of SEQ ID NO: 175; and (e) TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to any of SEQ IDNOs: 176 to 197, preferably TAIL comprises or consists of the amino acid sequence of anyof SEQ ID NOs: 176 to 197; and (ii) m is from 2 to 100, from 2 to 95, from 2 to 90, from 2 to85, from 2 to 80, from 2 to 75, from 2 to 70, from 2 to 65, from 2 to 60, from 2 to 55, from 2 to 50, from 2 to 45, from 2 to 40, from 2 to 35, from 2 to 30, from 2 to 29, from 2 to 28, from 2 to 27, from 2 to 26, from 2 to 25, from 2 to 24, from 2 to 23, from 2 to 22, from 2 to 21, from 2 to 20, from 2 to 19, from 2 to 18, from 2 to 17, from 2 to 16, from 2 to 15, from 2 to 14, from 2 to 13, from 2 to 12, from 2 to 11, from 2 to 10, from 2 to 9, from 2 to 8, from 3 to 8, or from 4 to 8, preferably m is 4. In some embodiments: (1) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 11; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; CCAP comprisesor consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (2) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 12; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (3) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 13; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 39; CCAP comprises or consists of an amino acid sequence having at least90% sequence identity to SEQ ID NO: 46; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (4) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 14; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (5) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 15; NCAP comprises or consists of an amino acid sequence having at least90% sequence identity to SEQ ID NO: 38; CCAP comprises or consists of an amino acidsequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (6) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 16; NCAP comprises or consists of an amino acidsequence having at least 90% sequence identity to SEQ ID NO: 38; CCAP comprises orconsists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (7) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 17; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (8) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 18; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity toSEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence having at least90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (9) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 19; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 47; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (10) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 20; NCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 40; CCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 191; (11) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 20; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; CCAP comprisesor consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (12) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 21; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (13) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 22; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (14) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 23; NCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 41; CCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (15) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 24; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 41; CCAP comprisesor consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (16) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 25; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (17) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 20; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 42; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (18) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 26; NCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 38; CCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (19) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 27; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; CCAP comprisesor consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (20) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 28; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 48; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (21) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 29; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (22) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 30; NCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 43; CCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (23) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 31; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 43; CCAP comprisesor consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (24) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 32; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (25) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 19; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 49; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (26) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 33; NCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 38; CCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (27) UNITSn comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 34; NCAP comprises or consists of an aminoacid sequence having at least 90% sequence identity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; (28) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 35; NCAP comprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO:38; CCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176; or (29) UNITSncomprises or consists of an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 36; NCAP comprises or consists of an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 38; CCAP comprises or consists of an amino acid sequence havingat least 90% sequence identity to SEQ ID NO: 45; and TAIL comprises or consists of an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 176. In some embodiments: (1) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 11; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAILcomprises or consists of the amino acid sequence of SEQ ID NO: 176; (2) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 12; NCAP comprises orconsists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of theamino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (3) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 13; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:39; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 46; and TAILcomprises or consists of the amino acid sequence of SEQ ID NO: 176; (4) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 14; NCAP comprises orconsists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of theamino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (5) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 15; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAILcomprises or consists of the amino acid sequence of SEQ ID NO: 176; (6) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 16; NCAP comprises orconsists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of theamino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (7) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 17; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAILcomprises or consists of the amino acid sequence of SEQ ID NO: 176; (8) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 18; NCAP comprises orconsists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of theamino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (9) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 19; NCAP comprises or consists of the amino acid sequence of SEQ ID NO:38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 47; and TAILcomprises or consists of the amino acid sequence of SEQ ID NO: 176; (10) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 20; NCAP comprises orconsists of the amino acid sequence of SEQ ID NO: 40; CCAP comprises or consists of theamino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 191; (11) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 20; NCAP comprises or consists of the amino acid sequence ofSEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO:45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (12) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 21; NCAPcomprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises orconsists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (13) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 22; NCAP comprises or consists of the amino acidsequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence ofSEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (14) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 23; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 41; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (15) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 24; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 41; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (16) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 25; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (17) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 20; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 42; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (18) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 26; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (19) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 27; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (20) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 28; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 48; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (21) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 29; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (22) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 30; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 43; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (23) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 31; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 43; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (24) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 32; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (25) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 19; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 49; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (26) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 33; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (27) UNITSn comprises or consists of the amino acid sequence of SEQ ID NO: 34; NCAP comprises or consists of the aminoacid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequenceof SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; (28) UNITSncomprises or consists of the amino acid sequence of SEQ ID NO: 35; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acid sequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence of SEQ ID NO: 176; or (29) UNITSn comprises orconsists of the amino acid sequence of SEQ ID NO: 36; NCAP comprises or consists of the amino acid sequence of SEQ ID NO: 38; CCAP comprises or consists of the amino acidsequence of SEQ ID NO: 45; and TAIL comprises or consists of the amino acid sequence ofSEQ ID NO: 176. Example polypeptide sequences Example polypeptide sequences are provided in SEQ ID NOs: 198 to 226.In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% sequence similarity to any of SEQ ID NOs: 198 to226. In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% sequence identity to any of SEQ ID NOs: 198 to226. In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or 100.0% sequencesimilarity to any of SEQ ID NOs: 198 to 226.In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or 100.0% sequenceidentity to any of SEQ ID NOs: 198 to 226.In some embodiments, the polypeptide comprises or consists of the sequence of any of SEQ ID NOs: 198 to 226. In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% sequence similarity to any of SEQ ID NOs: 198-204. In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% sequence identity to any of SEQ ID NOs: 198-204.In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or 100.0% sequencesimilarity to any of SEQ ID NOs: 198-204. In some embodiments, the polypeptide comprises or consists of an amino acid sequence having at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or 100.0% sequenceidentity to any of SEQ ID NOs: 198-204.In some embodiments, the polypeptide comprises or consists of the sequence of any of SEQID NOs: 198-204. In some embodiments, the polypeptide comprises or consists of an amino acid sequencehaving at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% sequence similarity to SEQ ID NO: 198.In some embodiments, the polypeptide comprises or consists of an amino acid sequencehaving at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, atleast 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% sequence identity to SEQ ID NO: 198.In some embodiments, the polypeptide comprises or consists of an amino acid sequencehaving at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or 100.0% sequencesimilarity to SEQ ID NO: 198. In some embodiments, the polypeptide comprises or consists of an amino acid sequencehaving at least 99.0%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, or 100.0% sequenceidentity to SEQ ID NO: 198.In some embodiments, the polypeptide comprises or consists of the sequence of SEQ IDNO: 198. Variants, derivatives, and fragmentsIn addition to the specific polypeptide sequences described herein, the invention alsoencompasses variants, derivatives, and fragments thereof.In the context of the invention, a “variant” of any given amino acid sequence is an amino acidsequence in which the specific sequence of amino acid residues has been modified in sucha manner that the amino acid sequence in question retains at least partial or full activity (e.g.the ability to form one or more beta solenoid domains). A variant amino acid sequence can be obtained by addition, deletion, substitution, modification, replacement and / or variation ofat least one amino acid residue present in a given amino acid sequence.The term “derivative” as used herein in relation to amino acid sequences of the inventionincludes any substitution of, variation of, modification of, replacement of, deletion of and / oraddition of one (or more) amino acid residues from or to a given amino acid sequence,providing that the resultant amino acid sequence retains at least partial or full activity (e.g.the ability to form one or more beta solenoid domains). Typically, amino acid substitutions may be made, for example from 1, 2 or 3, to 10 or 20substitutions, provided that the modified amino acid sequence retains at least partial or fullactivity (e.g. the ability to form one or more beta solenoid domains). Amino acid substitutions may include the use of non-naturally occurring analogues. Amino acid sequences may have deletions, insertions or substitutions of amino acid residues which produce a silent change and result in a functionally equivalent amino acid sequence. Deliberate amino acid substitutions may be made on the basis of similarity in polarity, charge, solubility, hydrophobicity, hydrophilicity and / or the amphipathic nature of theresidues as long as at least partial or full activity (e.g. the ability to form one or more betasolenoid domains) is retained. For example, negatively charged amino acids include aspartic acid and glutamic acid; positively charged amino acids include lysine and arginine; and amino acids with uncharged polar head groups having similar hydrophilicity values include asparagine, glutamine, serine, threonine and tyrosine. Conservative substitutions may be made, for example according to the table below. Amino acids in the same block in the second column and preferably in the same line in the third column may be substituted for each other: The effect of additions, deletions, substitutions, modifications, replacements and / orvariations may be predicted using any suitable prediction tool e.g. SIFT (Vaser, R., et al.,2016. Nature protocols, 11(1), pp.1-9), PolyPhen-2 (Adzhubei, I., et al., 2013. Current protocols in human genetics, 76(1), pp.7-20), CADD (Rentzsch, P., et al., 2021. Genome medicine, 13(1), pp.1-12), REVEL (Ioannidis, N.M., et al., 2016. The American Journal of Human Genetics, 99(4), pp.877-885), MetaLR (Dong, C., et al., 2015. Human molecular genetics, 24(8), pp.2125-2137), and / or MutationAssessor (Reva, B., et al., 2011. Nucleic acids research, 39(17), pp.e118-e118).A variant amino acid sequence can be considered in terms of sequence similarity (i.e. aminoacid residues having similar chemical properties / functions) or sequence identity. In thepresent context, a variant amino acid sequence may include an amino acid sequence havingat least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least80%, at least 85% or at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% similarity or identity tothe subject amino acid sequence. In preferred embodiments, a variant amino acid sequenceis considered in terms of sequence identity.Suitably, reference to an amino acid sequence which has a percent similarity or identity toany one of the SEQ ID NOs detailed herein refers to an amino acid sequence which has thestated percent similarity or identity over the entire length of the SEQ ID NO referred to.Sequence similarity or identity comparisons can be conducted by eye, or more usually, withthe aid of readily available sequence comparison programs. These commercially availablecomputer programs can calculate percent similarity or identity between two or more aminoacid sequences.Percent similarity or identity may be calculated over contiguous amino acid sequences, i.e.one amino acid sequence is aligned with the other amino acid sequence and each aminoacid in one sequence is directly compared with the corresponding amino acid in the other sequence, one amino acid residue at a time. This is called an “ungapped” alignment. Typically, such ungapped alignments are performed only over a relatively short number of amino acid residues. Although this is a very simple and consistent method, it fails to take into consideration that,for example, in an otherwise identical pair of amino acid sequences, one insertion or deletionin the amino acid sequence may cause the following amino acid residues to be put out ofalignment, thus potentially resulting in a large reduction in percent similarity or identity whena global alignment is performed. Consequently, most sequence comparison methods are designed to produce optimal alignments that take into consideration possible insertions anddeletions without penalising unduly the overall similarity or identity score. This is achieved byinserting “gaps” in the sequence alignment to try to maximise local similarity or identity. However, these more complex methods assign “gap penalties” to each gap that occurs in the alignment so that, for the same number of identical amino acids, a sequence alignment with as few gaps as possible, reflecting higher relatedness between the two comparedamino acid sequences, will achieve a higher score than one with many gaps. “Affine gapcosts” are typically used that charge a relatively high cost for the existence of a gap and a smaller penalty for each subsequent residue in the gap. This is the most commonly used gap scoring system. High gap penalties will produce optimised alignments with fewer gaps. Most alignment programs allow the gap penalties to be modified. However, it is preferred to use the default values when using such software for sequence comparisons. For example, when using the GCG Wisconsin Bestfit package the default gap penalty for amino acid sequences is -12 for a gap and -4 for each extension.Calculation of maximum percent similarity or identity therefore firstly requires the productionof an optimal alignment, taking into consideration gap penalties. A suitable computer program for carrying out such an alignment is the GCG Wisconsin Bestfit package (see e.g. Devereux, J., et al., 1984. Nucleic acids research, 12(1), pp.387-395). Examples of other software that can perform sequence comparisons include, but are not limited to, the BLAST package (see e.g. Altschul, S.F., et al., 1990. Journal of molecular biology, 215(3), pp.403- 410), BLAST 2 (see e.g. Tatusova, T.A. and Madden, T.L., 1999. FEMS microbiology letters, 174(2), pp.247-250), FASTA (see e.g. Pearson, W.R. and Lipman, D.J., 1988. PNAS, 85(8), pp.2444-2448.), EMBOSS Needle (Madeira, F., et al., 2019. Nucleic acids research, 47(W1), pp.W636-W641) and the GENEWORKS suite of comparison tools. For some applications, it is preferred to use EMBOSS Needle.Although the final percent similarity or identity can be measured, the alignment process itselfis typically not based on an all-or-nothing pair comparison. Instead, a scaled similarity score matrix is generally used that assigns scores to each pairwise comparison based on chemical similarity or evolutionary distance. An example of such a matrix commonly used is the BLOSUM62 matrix. Once the software has produced an optimal alignment, it is possible to calculate percentsequence similarity or identity. The software typically does this as part of the sequencecomparison and generates a numerical result. The percent sequence similarity may becalculated as the number of similar residues (i.e. amino acid residues having similarchemical properties / functions) as a percentage of the total residues in the SEQ ID NOreferred to. The percent sequence identity may be calculated as the number of identicalresidues as a percentage of the total residues in the SEQ ID NO referred to.The term “fragment” as used herein refers to a variant amino acid sequence that is a portionof a full-length amino acid sequence. Fragments are typically selected regions of the aminoacid sequence that is of interest either functionally or, for example, in an assay and mayretain at least partial or full activity (e.g. the ability to form one or more beta solenoiddomains).Such variants, derivatives, and fragments may be prepared using standard recombinantDNA techniques such as site-directed mutagenesis. Where insertions are to be made,synthetic DNA encoding the insertion together with 5’ and 3’ flanking regions correspondingto the given sequence either side of the insertion site may be made. The flanking regions willcontain convenient restriction sites corresponding to sites in the given sequence so that thesequence may be cut with the appropriate enzyme(s) and the synthetic DNA ligated into the cut. The DNA is then expressed in accordance with the invention to make the encoded polypeptide. These methods are only illustrative of the numerous standard techniques known in the art for manipulation of DNA sequences and other known techniques may also be used. CompositionsThe present invention provides a composition comprising the polypeptide of the invention.The composition may comprise the polypeptide at a concentration of at least 20 mg / ml, atleast 30 mg / ml, at least 40 mg / ml, at least 50 mg / ml, at least 60 mg / ml, at least 70 mg / ml, at least 80 mg / ml, at least 90 mg / ml, at least 100 mg / ml, at least 120 mg / ml, at least 130 mg / ml, at least 150 mg / ml, at least 170 mg / ml, at least 190 mg / ml, at least 200 mg / ml, at least 250 mg / ml, at least 300 mg / ml, at least 350 mg / ml, or at least 400 mg / ml.Preferably, the composition comprises the polypeptide in a non-denatured state. The skilledperson will be able to select a suitable solvent, for example an aqueous solution. Suitablesolvents may include, for example: a) a buffer selected from the group consisting of any oneor more of: MES, Bis-tris methane, ADA, ACES, Bis-tris propane, PIPES, MOPSO, Cholamine chloride, MOPS, BES, TES, HEPES, DIPSO, MOBS, Acetamidoglycine, TAPSO, TEA, POPSO, HEPPSO, EPS, HEPPS, Tricine, Tris, Glycinamide, Glycylglycine, HEPBS, Bicine, TAPS, AMPB, CHES, AMP, AMPSO CAPSO, CAPS, CABS, Bicine, sodium citratebuffer, sodium bicarbonate buffer, phosphate buffer, borate buffer, optionally wherein thebuffer comprises one or more salts, e.g. sodium chloride and / or potassium chloride,optionally wherein the buffer is at a pH range of 3 to 10, e.g. pH 7; b) an organic solvent,optionally HFIP.In some embodiments, the composition does not comprise a solvent in which thepolypeptide is not soluble. For example, in some embodiments, the composition does notcomprise ethanol, propanol, acetone, diethyl ether or DMSO.The compositions comprising the polypeptide of the invention may have a viscosity whichenables easier processing of the dope solution for wet-spinning. In some embodiments, thecomposition has a viscosity at ambient pressure and temperature (e.g. 25°C) and a shearrate of 100 s⁻¹ of 100 mPa.s or more, 200 mPa.s or more, 300 mPa.s or more, 400 mPa.s ormore, 500 mPa.s or more, 1000 mPa.s or more, or 1500 mPa.s or more. In someembodiments, the composition has a viscosity at ambient pressure and temperature (e.g.25°C) and a shear rate of 100 s⁻¹ of 10,000 mPa.s or less, 9,000 mPa.s or less, 8,000mPa.s or less, 7,000 mPa.s or less, 6,000 mPa.s or less, or 5,000 mPa.s or less. In someembodiments, the composition has a viscosity at ambient pressure and temperature (e.g.25°C) and a shear rate of 100 s⁻¹ of from 100 mPa.s to 10,000 mPa.s, from 1000 mPa.s to5,000 mPa.s, or from 1500 mPa.s to 5,000 mPa.s. The viscosity may be determined by anysuitable method, for example as described in the examples. PolynucleotidesThe present invention provides a polynucleotide encoding the beta solenoid fold, N-terminalcapping sequence, C-terminal capping sequence, beta solenoid domains, linked beta solenoid domains, or polypeptide of the invention. The polynucleotide may be double or single stranded, and may be RNA or DNA. The polynucleotide may be an isolated polynucleotide. It will be understood by a skilled person that numerous different polynucleotides can encode the same polypeptide as a result of the degeneracy of the genetic code. In addition, it is to be understood that the skilled person may, using routine techniques, make nucleotidesubstitutions, additions or deletions that do not affect the amino acid sequence encoded bythe polynucleotides of the invention to reflect the codon usage of any particular host organism in which the polypeptides of the invention are to be expressed. Polynucleotides such as DNA polynucleotides may be produced recombinantly, synthetically, or by any means available to those of skill in the art. They may also be cloned by standard techniques. Longer polynucleotides will generally be produced using recombinant means, for example using polymerase chain reaction (PCR) cloning techniques. This will involve making a pair of primers (e.g. of about 15 to 30 nucleotides) flanking the target sequence which it is desired to clone, bringing the primers into contact with mRNA or cDNA obtained from an animal or human cell, performing a polymerase chain reaction under conditions which bring about amplification of the desired region, isolating the amplified fragment (e.g. by purifying the reaction mixture with an agarose gel) and recovering the amplified DNA. The primers may be designed to contain suitable restriction enzyme recognition sites so that the amplified DNA can be cloned into a suitable vector. The polynucleotides described herein may be modified by any method available in the art.Such modifications may be carried out in order to enhance the in vivo activity or lifespan ofthe polynucleotides of the invention. VectorsThe present invention also provides a vector encoding the beta solenoid fold, N-terminalcapping sequence, C-terminal capping sequence, beta solenoid domains, linked beta solenoid domains, or polypeptide of the invention. The vectors of the present invention may comprise the polynucleotide of the invention.A “vector” is a tool that allows or facilitates the transfer of an entity from one environment toanother. In accordance with the invention, and by way of example, some vectors used inrecombinant nucleic acid techniques allow entities, such as a segment of nucleic acid (e.g. aheterologous DNA segment, such as a heterologous cDNA segment), to be transferred intoa target cell. The vector may serve the purpose of maintaining the heterologous nucleic acid (DNA or RNA) within the cell, facilitating the replication of the vector comprising a segmentof nucleic acid, or facilitating the expression of the polypeptide encoded by a segment ofnucleic acid. Examples of vectors used in recombinant nucleic acid techniques include, but are not limited to, plasmids, chromosomes, artificial chromosomes and viruses. The vector may be singlestranded or double stranded. The vector may be linear or circular. The vector may also be,for example, a naked nucleic acid (e.g. DNA).The term “vector" includes an expression vector i.e. a construct capable of in vivo or in vitro / exvivo expression. Expression may be controlled by a vector sequence, or, for example in thecase of insertion at a target site, expression may be controlled by a target sequence. A vector may be integrated or tethered to the cell’s DNA.The vectors of the invention may be, for example, plasmid or viral vectors and may include apromoter for the expression of a polynucleotide and optionally a regulator of the promoter. Inpreferred embodiments, the vector of the invention is a plasmid. CellsThe present invention also provides a cell comprising a polynucleotide or a vector of thepresent invention. The cell may be any cell type known in the prior art. The cell may be an isolated cell. Thecell may be a host cell. In some embodiments, the cell is any of: a) a prokaryotic cell,optionally a bacterial cell, e.g. an E. coli cell, a Bacillus subtilis cell, a Bacillus megateriumcell, a Vibrio natriegens cell, or a Pseudomonas fluorescens cell; or b) a eukaryotic cell,optionally a yeast cell, e.g. Pichia pastoris or Saccharomyces cerevisiae; an insect cell, e.g.a baculovirus infected insect cell; or a mammalian cell, e.g. a baculovirus infectedmammalian cell, a HEK293 cell, a HeLa cell, or a CHO cell. Fibres and yarnsThe present invention also provides a fibre comprising the beta solenoid fold, N-terminalcapping sequence, C-terminal capping sequence, beta solenoid domains, linked betasolenoid domains, or polypeptide of the invention. The polypeptides of the invention may besuitable for use in the formation of fibres with particularly beneficial properties. The fibres of the present invention may have an average diameter of from 100 nm to 100 µm, from 500 nm to 50µm, from 1 µm to 40 µm, from 2.5 µm to 35 µm, from 5 µm to 30 µm,from 7.5 µm to 25 µm, or from 10 µm to 20 µm. The average diameter may be determinedby any suitable method, for example as described in the examples.The fibres of the present invention may have a Young’s modulus of at least 0.5 GPa, at least1.0 GPa, at least 2.0 GPa, at least 5.0 GPa, at least 10.0 GPa, at least 15.0 GPa, at least20.0 GPa, at least 25.0 GPa, at least 30.0 GPa, at least 35.0 GPa, at least 40.0 GPa, atleast 50.0 GPa, at least 60.0 GPa, at least 70.0 GPa, at least 75.0 GPa, at least 80.0 GPa,at least 90.0 GPa, at least 100.0 GPa, at least 125 GPa, at least 150 GPa, at least 175 GPa,or at least 200 GPa. The fibres of the present invention may have a Young’s modulus offrom 0.5 GPa to 200 GPa, from 1.0 GPa to 200 GPa, from 2.0 GPa to 200 GPa, from 5.0GPa to 200 GPa, from 10.0 GPa to 200 GPa, from 15.0 GPa to 200 GPa, from 20.0 GPa to200 GPa, from 25.0 GPa to 200 GPa, from 30.0 GPa to 200 GPa, from 35.0 GPa to 200GPa, from 40.0 GPa to 200 GPa, from 45.0 GPa to 200 GPa, from 50.0 GPa to 200 GPa.The fibres of the present invention may have an engineered strength of: at least 0.1 GPa, atleast 0.2 GPa, at least 0.3 GPa, at least 0.4 GPa, at least 0.5 GPa, at least 0.6 GPa, at least 0.7 GPa, at least 0.8 GPa, at least 0.9 GPa, at least 1.0 GPa, at least 1.1 GPa, at least 1.2 GPa, at least 1.3 GPa, at least 1.4 GPa, at least 1.5 GPa, at least 1.6 GPa, at least 1.7 GPa, at least 1.8 GPa, at least 1.9 GPa, at least 2.0 GPa, at least 2.1 GPa, at least 2.2 GPa, at least 2.3 GPa, at least 2.4 GPa, at least 2.5 GPa, at least 2.6 GPa, at least 2.7 GPa, at least2.8 GPa, at least 2.9 GPa, at least 3.0 GPa. The fibres of the present invention may have anengineered strength of: from 0.1 GPa to 3.0 GPa, from 0.2 GPa to 3.0 GPa, from 0.3 GPa to3.0 GPa, from 0.4 GPa to 3.0 GPa, from 0.5 GPa to 3.0 GPa, from 0.6 GPa to 3.0 GPa, from0.7 GPa to 3.0 GPa, from 0.8 GPa to 3.0 GPa, from 0.9 GPa to 3.0 GPa, or from 1.0 GPa to3.0 GPa.The fibres of the present invention may have a tensile strength of at least 1 cN / tex, at least 2cN / tex, at least 3 cN / tex, at least 4 cN / tex, at least 5 cN / tex, at least 6 cN / tex, at least 7 cN / tex, at least 8 cN / tex, at least 9 cN / tex, or at least 10 cN / tex. The fibres of the presentinvention may have a tensile strength of 100 cN / tex or less, 90 cN / tex or less, 80 cN / tex orless, 70 cN / tex or less, 60 cN / tex or less, 50 cN / tex or less, 40 cN / tex or less, 30 cN / tex orless, 20 cN / tex or less, or 10 cN / tex or less. The fibres of the present invention may have atensile strength of from 1 cN / tex to 100 cN / tex, from 5 cN / tex to 100 cN / tex, or from 10cN / tex to 100 cN / tex. The tensile strength of the fibres may be determined by any suitablemethod, for example as described in the examples. The fibres of the present invention may have a strain to failure of at least 2%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 90%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, or at least 300%. The fibres ofthe present invention may have a strain to failure of 300% or less, 275% or less, 250% orless, 225% or less, 200% or less, 175% or less, 150% or less, 125% or less, or 100% orless. The fibres of the present invention may have a strain to failure of from 2% to 300%, from 5% to 300%, from 10% to 300%, from 15% to 300%, from 20% to 300%, from 25% to 300%, from 30% to 300%, from 35% to 300%, from 40% to 300%, from 45% to 300%, from 50% to 300%, from 55% to 300%, from 60% to 300%, from 65% to 300%, from 70% to 300%, from 75% to 300%, from 80% to 300%, from 90% to 300%, or from 100% to 300%.The fibres of the present invention may have a toughness of at least 10 J / g, at least 20 J / g,at least 40 J / g, at least 60 J / g, at least 80 J / g, at least 100 J / g, at least 120 J / g, at least 140 J / g, at least 160 J / g, at least 180 J / g, at least 200 J / g, at least 250 J / g, at least 300 J / g, at least 350 J / g, at least 400 J / g, at least 450 J / g, at least 500 J / g, at least 550 J / g, at least 600 J / g, at least 650 J / g, at least 700 J / g, at least 750 J / g, at least 800 J / g, at least 850 J / g, at least 900 J / g, at least 950 J / g, at least 1000 J / g. The fibres of the present invention mayhave a toughness of from 10 J / g to 1000 J / g, from 20 J / g to 1000 J / g, from 40 J / g to 1000 J / g, from 60 J / g to 1000 J / g, from 80 J / g to 1000 J / g, from 100 J / g to 1000 J / g, from 120 J / g to 1000 J / g, from 140 J / g to 1000 J / g, from 160 J / g to 1000 J / g, from 180 J / g to 1000 J / g, or from 200 J / g to 1000 J / g.The fibres of the present invention may have a toughness of at least 10 M / m3, at least 20M / m3, at least 30 M / m3, at least 40 M / m3, at least 50 M / m3, at least 60 M / m3, at least 70M / m3, at least 80 M / m3, or at least 90 M / m3. The fibres of the present invention may have atoughness of 150 M / m3or less, 120 M / m3or less, or 100 M / m3or less. The fibres of the present invention may have a toughness of from 10 M / m3to 150 M / m3, from 50 M / m3to 120 M / m3, or from 80 M / m3to 100 M / m3. The toughness of the fibres may be determined by any suitable method, for example as described in the examples.The fibres of the invention may be made by any means. Typically, the fibres of the presentinvention may be made by spinning the polypeptides of the invention, or by otherwisecombining the polypeptides of the invention into a fibre. In some embodiments, thepolypeptides in the fibre are the same, i.e. the fibre comprises polypeptides of the sameamino acid sequence. In other embodiments, the fibres comprise different polypeptides, i.e.comprise polypeptides with different amino acid sequences, for example the fibres maycomprise polypeptides with at least 2 different amino acid sequences, for example at least 3,at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, or at least 10 different aminoacid sequences. For example, beta solenoid domains with different cross-sectional shapesmay be linked within a single polypeptide.The fibres of the invention may be made by a wet-spinning method which is well known inthe art, for example using a microfluidic wet-spinning device. To spin the polypeptides intofibres, typically the polypeptide, which is dissolved in a particular solvent, is spun into ananti-solvent, or coagulation solution, in which the polypeptide is not as soluble and willtherefore precipitate. Coagulation spinning is standard in the art and typically involves the spinning solution being passed through a spinneret of one to many (e.g. thousands) of holes to define individual strands which are then consolidated, wound up and treated (e.g. stretched, annealed, dried, coated) to optimise performance. The skilled person will understand how to select suitable coagulation solvents. For example,where the polypeptide is dissolved in an aqueous solution, the coagulation solvent may beethanol. A further approach could be to coagulate proteins using a change in pH, for example proteins are known to be least soluble at their isoelectric point. A further approach could be to induce protein coagulation in aqueous solution using salts containing divalent or trivalent cations (e.g. calcium chloride). Non-aqueous coagulants could include ethanol, methanol, acetone, propanol, diethyl ether, or DMSO. Another approach could be a coagulation solution containing a mixture of the above approaches. The skilled person will understand that the dope solvent and coagulation solvent should be selected to minimise protein denaturation and maximise retention of the structural features ofthe polypeptide both before and after spinning. The retention of the desired ordered solenoidpost spinning can be confirmed by various methods including X-ray diffraction studies of the resulting fibres. The skilled person will appreciate that small diameter filaments can also be made by evaporation or dry spinning, electrospinning, solution blow spinning, centrifugal forcespinning, and the like which do not require a coagulation solution.The present invention also provides a yarn comprising the fibre of the invention. In someembodiments, the fibres in the yarn are the same. In other embodiments, the yarn comprisesdifferent fibres, for example comprises at least 2, at least 3, at least 4, at least 5, at least 6,at least 7, at least 8, at least 9, or at least 10 different fibres. Textiles, uses, and textile products The invention also provides a textile or fabric comprising the beta solenoid fold, N-terminal capping sequence, C-terminal capping sequence, beta solenoid domains, linked beta solenoid domains, polypeptide, fibre, or yarn according to the invention. The textile or fabricmay be woven or non-woven and / or may be coated in sizing.Example applications of the fibres, yarns, fabrics and textiles present invention are in theproduction of: Sportswear (e.g. for protective uses such as rash guards); Protective wear formotorcyclists and / or other motorsports; Personal protective equipment (e.g. body armour, protective underwear for soldiers); Blast containment; Blade containment (e.g. for aircraft engines); Textiles for parachutes; Ropes; Textiles for clothing; Textiles for shoes; and the like. The fibres, yarns, fabrics and textiles of the present invention are also considered to have a number of medical applications which include: General medical textiles; Wound dressings; Resorbable and non-resorbable surgical sutures; Resorbable and non-resorbable stents; Guide-wires for surgery (including non-metallic guide wires suitable for MRI); Biocompatible coatings for implanted medical devices; Surgical meshes; Scaffolds for 3D tissueengineering; and the like. The practice of the present invention will employ, unless otherwise indicated, conventional techniques of chemistry, biochemistry, and molecular biology, which are within the capabilities of a person of ordinary skill in the art. Such techniques are explained in the literature. See, for example: Skoog, D.A., et al. (2013) Fundamentals of AnalyticalChemistry, 9th edition, Cengage learning; Walker J.M. (2009) The Protein ProtocolsHandbook, 3rd edition, Springer Nature; Green, M.R. and Sambrook, J. (2012) MolecularCloning: A Laboratory Manual, 4th Edition, Cold Spring Harbor Laboratory Press; Ausubel,F.M., et al. (2003) Current Protocols in Molecular Biology, John Wiley & Sons; Hill, A. J.(2013) DNA Sequencing Protocols, Humana Press; Nielsen, B.S. and Jones, J. (2021) In Situ Hybridization Protocols, Springer US; Herdewijn, P. (2010) Oligonucleotide Synthesis: Methods and Applications, Humana Press; and Luo, Y. (2019) CRISPR Gene Editing:Methods and Protocols, Springer New York. Each of these general texts is herein incorporated by reference. EXAMPLES The invention will now be further described by way of examples, which are meant to serve to assist one of ordinary skill in the art in carrying out the invention and are not intended in any way to limit the scope of the invention. Example 1 – Design and Production of Protein-Based FibresThe following polypeptide sequences, each comprising four beta solenoid domainsconnected by linkers, were designed using computational protein design methods: An example of a method for protein expression and purification is provided below. pMK_RQ plasmid coding for a polypeptide were ordered from GeneArt (Thermo Fisher). Thegene was then further cloned into pMK_RQ GeneArt cloning plasmid with additional flanking T7 promoter, RBS and terminator sequences. Once the DNA sequence of the plasmid was confirmed it was then transformed into KRX (Promega) E.coli strain. Alternatively, aBL21(DE3) E.coli strain and pET-28a plasmid may be used for expression.8x 1 L flasks containing TB medium (supplemented with Kanamycin and 0.0005 % Antifoam 204 (v / v) (Merck)) were inoculated with 80 mL LB overnight cultures comprising thetransformed E. coli. The 1 L cultures were grown at 37°C until reaching an OD600 reading of 0.7. Expression was then induced with 0.1% filter sterilised rhamnose (w / v) and the cultures grown overnight at 25 °C. Cells were harvested and resuspended in lysis buffer (20 mM Bicine and 150 mM NaCl buffer titrated to pH 9.0 with NaOH). The cells were sonicated and clarified by centrifugation at 47,000 × g for 60 min. The proteins were purified with a nickel-nitrilotriacetic acid (Ni-NTA) column; washed with 20 mM Bicine and 150 mM NaCl at pH 9.0; and eluted in 20 mM Bicine, 150 mM NaCl, and 500 mM Imidazole at pH 9.0.The Ni-NTA affinity purified proteins were optionally further applied to an ion exchange chromatography 20 mL Hi Trap Q HP (Cytiva) column and washed with 20 mM Bicine (pH 9.0) buffer containing an increasing concentration of NaCl. Various protein fractions werecollected during the ion exchange chromatography purification and sampled for SDS-PAGEanalysis. Eluted fractions were collected and buffer exchanged into 20 mM Bicine, 150 mL NaCl, pH 9.0 using 7 kDa molecular weight cut-off dialysis tubing. The purified protein was concentrated to ~350–360 mg / mL using 10 kDa cut-off centrifugal concentrators. The protein samples were flash-frozen in liquid nitrogen and stored at -20°C for subsequence wet-spinning. A concentrated aqueous protein solution is used as the dope solution for wet-spinning. The dope is extruded through a spinneret into a coagulation bath comprising an ethanol / water mixture to induce solidification. The spinning line comprises sequentially: a precision pump to control flow rate, the spinneret, a series of driven godets for fibre drawing, and a winding unit for fibre collection. The configuration permits adjustment of spinning parameters and draw ratios to control fibre morphology and mechanical properties. Example 2 – Testing Protein-Based FibresThe proteins designed were tested by the methods described below and demonstrated tohave improved properties (e.g. solubility, viscosity, spinnability, stretch, strength, and toughness). Viscosity of protein-based spinning dopes was measured using a stress-controlled rotationalrheometer, as described below. The majority of the protein-based spinning dopes hadacceptable viscosity. Notably, some protein-based spinning dopes exhibited a high viscosityresulting in pressure build-up in the spinneret and others exhibited only very low viscositywhich impeded the formation of filaments. Spinnability was assessed by evaluating the ability of a protein solution (dope) to formcontinuous fibre under defined wet spinning conditions without breakage, clogging, or instability, as described below. The majority of the protein-based spinning dopes hadacceptable spinnability. Results for some of the best-performing proteins are provided in the table below. _ The diameter of the filament was measured using an optical microscope. Examples of microscopy images are provided in Figure 1. Results for the average filament diameter and draw ratio of protein-based fibres are provided below: _Tensile properties of protein-based fibres are evaluated using a constant-rate-extension, as described below. Tensile testing results are shown in Figure 2. Figure 2A shows results for several protein-based fibres tested and Figure 2B shows the improvement from c_18 compared to l6. Toughness results are shown in Figure 3, which demonstrates that some of the protein-based fibres tested had higher toughness than Nylon 66 and Kevlar 49 (see Angew Chem Int Ed Engl (2009) 48:3584-3596; Adv Sci (2022) 9:e2103965). Viscosity Measurement Method for Protein-Based Spinning Dopes Viscosity of protein-based spinning dopes is measured using a stress-controlled rotational rheometer (e.g. Anton Paar MCR 92 or equivalent) operated under ambient pressure with an air-bearing system supplied at 6 bar. The instrument is allowed to thermally equilibrate for at least one hour prior to measurement, and motor and encoder calibrations are performed as per manufacturer recommendations. Measurements are performed using a parallel plate geometry comprising a 25 mm diameter stainless steel upper plate and a stainless steel bottom plate, with a fixed measurement gap of 0.4 mm. In alternative implementations, other geometries may be employed, including cone-plate systems (e.g.50 mm diameter, 1° cone angle) or concentric cylinder systems, provided that consistent temperature control and shear rate accuracy are maintained. The rheometer is controlled using proprietary software (e.g. RheoCompass) and operated at a test temperature of 25 °C. For each measurement, 350–400 µL of the protein dope is deposited onto the lower plate. The sample is inspected to ensure absence of visible air bubbles, and the perimeter is sealed with silicone oil to prevent dehydration during testing. The upper plate is lowered to a trimming position to remove excess sample, then positioned at the defined measurement gap. The measurement protocol consists of a continuous, logarithmic shear rate ramp from 0.01 s⁻¹ to 100 s⁻¹ over a 5-minute interval. Apparent viscosity (reported in millipascal- seconds, mPa·s) is recorded at each shear rate. The apparent viscosity at the maximum applied shear rate of 100 s⁻¹ is used as a proxy for the spinning viscosity, which corresponds to the estimated shear conditions experienced during wet fibre extrusion. This protocol enables direct comparison of rheological behaviour across dopes of differing protein concentration, formulation, sequence, or processing history, and supports evaluation of shear thinning properties and processability in wet spinning applications. determination Spinnability may be assessed by evaluating the ability of a protein solution (dope) to form continuous fibre under defined wet spinning conditions without breakage, clogging, or instability. In this method, the dope is extruded through a spinneret into a coagulation bath and drawn through a standard take-up system, with the total length of uninterrupted fibre produced serving as a primary metric. Spinnability can be evaluated across a range ofvariables, including but not limited to dope composition (e.g. protein sequence / identity,concentration, additives, rheology), spinning parameters (e.g. extrusion rate, draw speed, spinneret geometry), protein sequence or construct, and coagulation bath composition (e.g. solvent identity, temperature, coagulant concentration). Systematic variation of these parameters allows for comparative assessment of formulation and process robustness. The threshold length of continuous fibre produced under each condition, and the maximum operational window before fibre failure, provide a quantitative and reproducible basis for ranking spinnability across different material and process configurations. Tensile Testing Method for Protein-Based Fibres Tensile properties of protein-based fibres are evaluated using a constant-rate-extension method on a Zwick Roell Z0.5TN tensile tester fitted with a 10 N load cell and spring-loaded grips (20 N capacity). Fibre samples are conditioned at 21 °C and 65% relative humidity for 12–24 hours in accordance with ASTM D1776. Prior to testing, multifilament or monofilament fibres are unwound from the bobbin, and 10 individual samples of 7 cm length are prepared. For each fibre, three diameter measurements are taken via reflection-mode optical microscopy at 20× magnification to determine the average filament diameter, which is used to calculate tensile stress in megapascals (MPa). Filament sections are flattened between glass slides for imaging, and at least five independent regions of fibre are analysed to obtain representative statistics for cross-sectional area. Fibre mass is determined by weighing an 8 metre segment on an analytical balance, and linear density is calculated as: linear density [dtex] = (mass [g] × 10,000) / (length [m]). Although tensile strength is primarily reported in MPa using measured filament diameters, linear density values may optionally be used to calculate tenacity in cN / dtex. During mechanical testing, fibres are clamped with a gauge length of 25 mm and subjected to a crosshead speed of 25 mm / min. A pre-load of 0.001 N is applied, corresponding to approximately 0.06 cN / dtex, to straighten the fibre prior to clamping. The test terminates at80% drop from the peak force or 0.1% of the nominal force (i.e. 0.1% of 10 N. load cell),whichever occurs first. Samples are excluded if breakage occurs within 2 mm of the clamps. At least five valid replicates are tested per condition, and for each, the maximum force, elongation at break, breaking force, and sample cross-sectional area are recorded. Tensile strength is calculated as the maximum force divided by the estimated cross-sectional area, using the measured filament diameter and assuming a circular cross-section. Data outputs include force-displacement curves, calculated tensile strengths, and failure annotations.

Claims

CLAIMS1. A beta solenoid domain comprising or consisting of an amino acid sequence having atleast 90% identity to any of SEQ ID NOs: 51 to 79.

2. The beta solenoid domain according to claim 1, wherein the beta solenoid domaincomprises or consists of an amino acid sequence having at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%identity to any of SEQ ID NOs: 51 to 79.

3. The beta solenoid domain according to claim 1 or 2, wherein the beta solenoid domaincomprises a beta solenoid fold comprising or consisting of the amino acid sequence:(AX1X2X3X4)n(SEQ ID NO: 6), wherein X1is any amino acid, wherein X2is L or F, wherein X3is any amino acid, wherein X4is any amino acid, and wherein n is from 25 to 30, preferably wherein n is 27.

4. The beta solenoid domain according to any preceding claim, wherein the beta solenoid domain comprises an N-terminal capping sequence comprising or consisting of the aminoacid sequence: XMXXXXILXXYXXGXXXFXXIXLXXX1XLXX (SEQ ID NO: 37), wherein X isany amino acid, and wherein X1 is I or A.

5. The beta solenoid domain according to any preceding claim, wherein the beta solenoid domain comprises a C-terminal capping sequence comprising or consisting of the amino acid sequence: AXX1XXAXX2XXAXX3XXAXVXPVLWXXAXLXGAXX4XXXXXXXX5XXAXX(SEQ ID NO: 44), wherein X is any amino acid, wherein X1 is T or L or F, wherein X2 is L orF, wherein X3 is L or F, wherein X4 is M or V, and wherein X5 is Y or F.

6. The beta solenoid domain according to any preceding claim, wherein the beta solenoiddomain comprises or consists of the amino acid sequence of any of SEQ ID NOs: 51 to 79.

7. The beta solenoid domain according to any preceding claim, wherein the beta solenoid domain comprises or consists of an amino acid sequence having at least 95% identity to SEQ ID NO:

51.

8. The beta solenoid domain according to any preceding claim, wherein the beta solenoid domain comprises or consists of an amino acid sequence having at least 98% identity to SEQ ID NO: 51.

9. The beta solenoid domain according to any preceding claim, wherein the beta solenoid domain comprises or consists of an amino acid sequence having at least 99% identity to SEQ ID NO:

51.

10. The beta solenoid domain according to any preceding claim, wherein the beta solenoid domain comprises or consists of the amino acid sequence of SEQ ID NO:

51.

11. A polypeptide comprising or consisting of an amino acid sequence having at least 90% identity to SEQ ID NO: 51.

12. The polypeptide according to claim 11, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 95% identity to SEQ ID NO: 51.

13. The polypeptide according to claim 11, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 98% identity to SEQ ID NO: 51.

14. The polypeptide according to claim 11, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 99% identity to SEQ ID NO: 51.

15. The polypeptide according to claim 11, wherein the polypeptide comprises or consists ofthe amino acid sequence of SEQ ID NO:

51.

16. A polypeptide comprising two beta solenoid domains linked by a flexible linker, wherein each of the two beta solenoid domains are defined according to any of claims 1-11.

17. The polypeptide according to claim 16, wherein the flexible linker is selected from anypoly-glycine linkers, poly-alanine linkers, poly-serine linkers, glycine-rich linkers, alanine-richlinkers, serine-rich linkers, glycine- and alanine-rich linkers, glycine- and serine-rich linkers,and glycine / alanine / serine-rich linkers.

18. The polypeptide according to claim 16 or 17, wherein the flexible linker comprises orconsists of the amino acid sequence (G / A / S)x, wherein x is from 3 to 50.

19. The polypeptide according to any of claims 16-18, wherein the flexible linker comprises or consist of an amino acid sequence selected from: (Gly)3, (Ala)3, (Ser)3, GS, AG, TG, GGS, TGS, or any of SEQ ID NOs: 80-145, preferably wherein the flexible linker comprises orconsists of SEQ ID NO: 145.

20. The polypeptide according to any of claims 16-19, wherein the amino acid sequences of the two beta solenoid domains are identical.

21. The polypeptide according to any of claims 16-20, wherein the polypeptide comprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any ofSEQ ID NOs: 146 to 174, preferably SEQ ID NO: 146.

22. The polypeptide according to any of claims 16-21, wherein the polypeptide comprisesthe amino acid sequence of any of SEQ ID NOs: 146 to 174, preferably SEQ ID NO: 146.

23. A polypeptide comprising or consisting of an amino acid sequence having at least 90% identity to SEQ ID NO: 146.

24. The polypeptide according to claim 23, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 95% identity to SEQ ID NO: 146.

25. The polypeptide according to claim 23, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 98% identity to SEQ ID NO: 146.

26. The polypeptide according to claim 23, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 99% identity to SEQ ID NO: 146.

27. The polypeptide according to claim 23, wherein the polypeptide comprises or consists ofthe amino acid sequence of SEQ ID NO:

146.

28. The polypeptide according to any of claims 23-27, wherein (N)x is a flexible linker, preferably defined according to any of claims 17-19.

29. A beta solenoid fold comprising or consisting of an amino acid sequence having at least90% identity to any of SEQ ID NOs: 23 to 36.

30. The beta solenoid fold according to claim 29, wherein the beta solenoid fold comprisesor consists of an amino acid sequence having at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity toany of SEQ ID NOs: 23 to 36.

31. The beta solenoid fold according to claim 29 or 30, wherein the beta solenoid foldcomprises or consists of the amino acid sequence (AX1X2X3X4)n (SEQ ID NO: 6), wherein X1 is any amino acid, wherein X2 is L or F, wherein X3 is any amino acid, wherein X4 is anyamino acid, and fold n is from 25 to 30, preferably wherein n is 27.

32. The beta solenoid fold according to any of claims 29-31, wherein the beta solenoid foldcomprises or consists of the amino acid sequence of any of SEQ ID NOs: 23 to 36.

33. An N-terminal capping sequence comprising or consisting of an amino acid sequencehaving at least 90% identity to any of SEQ ID NOs: 39 to 43.

34. The N-terminal capping sequence according to claim 33, wherein the N-terminal cappingsequence comprises or consists of the amino acid sequence of SEQ ID NO: 37.

35. The N-terminal capping sequence according to claim 33 or 34, wherein the N-terminalcapping sequence comprises or consists of the amino acid sequence of any of SEQ ID NOs:39 to 43.

36. A C-terminal capping sequence comprising or consisting of an amino acid sequencehaving at least 90% identity to any of SEQ ID NOs: 46 to 49.

37. The C-terminal capping sequence according to claim 36, wherein the C-terminal cappingsequence comprises or consists of the amino acid sequence of SEQ ID NO: 44.

38. The C-terminal capping sequence according to claim 36 or 37, wherein the C-terminalcapping sequence comprises or consists of the amino acid sequence of any of SEQ ID NOs:46 to 49.

39. A beta solenoid domain comprising a beta solenoid fold according to any of claims 29-32, an N-terminal capping sequence according to any of claims 33-35, a C-terminal capping sequence according to any of claims 36-38, or any combination thereof.

40. A polypeptide comprising at least two beta solenoid domains, wherein the at least two beta solenoid domains are linked by a flexible linker, wherein the at least two beta solenoiddomains are defined according to any of claims 1-11 or claim 39.

41. The polypeptide according to claim 40, wherein the flexible linker is selected from anypoly-glycine linkers, poly-alanine linkers, poly-serine linkers, glycine-rich linkers, alanine-richlinkers, serine-rich linkers, glycine- and alanine-rich linkers, glycine- and serine-rich linkers,and glycine / alanine / serine-rich linkers.

42. The polypeptide according to claim 40 or 41, wherein the flexible linker comprises orconsist of the amino acid sequence (G / A / S)x, wherein x is from 3 to 50.

43. The polypeptide according to any of claims 40-41, wherein the flexible linker comprisesor consists of an amino acid sequence selected from: (Gly)3, (Ala)3, (Ser)3, GS, AG, TG,GGS, TGS, or any of SEQ ID NOs: 80-145, preferably wherein the flexible linker comprisesor consists of SEQ ID NO: 145.

44. The polypeptide according to any of claims 40-43, wherein the polypeptide further comprises a tag sequence, for example a His-tag, such as SEQ ID NO:

175.

45. The polypeptide according to any of claims 40-44, wherein the polypeptide further comprises a tail sequence, for example selected from any of SEQ ID NOs: 176-197.

44. The polypeptide according to any of claims 40-43, wherein the amino acid sequences of each of the at least two beta solenoid domains are identical.

45. The polypeptide according to any of claims 40-44, wherein the polypeptide comprises an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to any ofSEQ ID NOs: 198 to 226, preferably SEQ ID NO: 198.

46. The polypeptide according to any of claims 40-45, wherein the polypeptide comprisesthe amino acid sequence of any of SEQ ID NOs: 198 to 226, preferably SEQ ID NO: 198.

47. A polypeptide comprising or consisting of an amino acid sequence having at least 90% identity to SEQ ID NO: 198.

48. The polypeptide according to claim 47, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 95% identity to SEQ ID NO: 198.

49. The polypeptide according to claim 47, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 98% identity to SEQ ID NO: 198.

50. The polypeptide according to claim 47, wherein the polypeptide comprises or consists ofan amino acid sequence having at least 99% identity to SEQ ID NO: 198.

51. The polypeptide according to claim 47, wherein the polypeptide comprises or consists ofthe amino acid sequence of SEQ ID NO:

198.

52. A composition comprising the polypeptide according to any of claims 40-51.

53. The composition according to claim 52, wherein the composition comprises thepolypeptide at a concentration of at least 20 mg / ml, at least 30 mg / ml, at least 40 mg / ml, at least 50 mg / ml, at least 60 mg / ml, at least 70 mg / ml, at least 80 mg / ml, at least 90 mg / ml, or at least 100 mg / ml.

54. The composition according to claim 52 or 53, wherein the polypeptide is not denatured.

55. The composition according to any of claims 52 to 54, wherein the composition comprises a solvent.

56. A polynucleotide encoding the beta solenoid domain according to any of claims 1-11, the polypeptide according to any of claims 12-15, the polypeptide according to any of claims 16-22, the polypeptide according to any of claims 23-28, the beta solenoid fold according to anyof claims 29-32, the N-terminal capping sequence according to any of claims 33-35, the C- terminal capping sequence according to any of claims 36-38, the beta solenoid domainaccording to claim 39, or the polypeptide according to any of claims 40-51, preferablyencoding the polypeptide according to any of claims 40-51.

57. A vector comprising the polynucleotide according to claim 56.

58. A cell comprising the polynucleotide according to claim 56 or the vector according toclaim 57.

59. A fibre comprising the polypeptide according to any of claims 40-51.

60. The fibre according to claim 59, wherein the fibre has been produced via a wet-spinningmethod.

61. The fibre according to claim 59 or 60, wherein the fibre has an average diameter of from100 nm to 100 µm, from 500 nm to 50µm, from 1 µm to 40 µm, from 2.5 µm to 35 µm, from 5 µm to 30 µm, from 7.5 µm to 25 µm, or from 10 µm to 20 µm.

62. The fibre according to any of claims 59-61, wherein the fibre has a Young’s modulus ofat least 0.5 GPa, at least 1.0 GPa, at least 2 GPa, at least 5.0 GPa, at least 10.0 GPa, atleast 15.0 GPa, at least 20.0 GPa, at least 25.0 GPa, at least 30.0GPa, at least 35.0 GPa, atleast 40.0 GPa, at least 50.0 GPa, at least 60.0 GPa, at least 70.0 GPa, at least 75.0 GPa,at least 80.0 GPa, at least 90.0 GPa, at least 100.0 GPa, at least 125 GPa, at least 150GPa, at least 175 GPa, or at least 200 GPa.

63. The fibre according to any of claims 59-62, wherein the fibre has an engineered strength of: at least 0.1 GPa, at least 0.2 GPa, at least 0.3 GPa, at least 0.4 GPa, at least 0.5 GPa, at least 0.6 GPa, at least 0.7 GPa, at least 0.8 GPa, at least 0.9 GPa, at least 1.0 GPa, at least 1.1 GPa, at least 1.2 GPa, at least 1.3 GPa, at least 1.4 GPa, at least 1.5 GPa, at least 1.6 GPa, at least 1.7 GPa, at least 1.8 GPa, at least 1.9 GPa, at least 2.0 GPa, at least 2.1 GPa, at least 2.2 GPa, at least 2.3 GPa, at least 2.4 GPa, at least 2.5 GPa, at least 2.6 GPa, at least 2.7 GPa, at least 2.8 GPa, at least 2.9 GPa, or at least 3.0 GPa.

64. The fibre according to any of claims 59-63, wherein the fibre has a strain to failure of at least 2%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 90%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, or at least 300%.

65. The fibre according to any of claims 59-64, wherein the fibre has a toughness of at least 10 J / g, at least 20 J / g, at least 40 J / g, at least 60 J / g, at least 80 J / g, at least 100 J / g, at least 120 J / g, at least 140 J / g, at least 160 J / g, at least 180 J / g, at least 200 J / g, at least 250 J / g, at least 300 J / g, at least 350 J / g, at least 400 J / g, at least 450 J / g, at least 500 J / g, at least 550 J / g, at least 600 J / g, at least 650 J / g, at least 700 J / g, at least 750 J / g, at least 800 J / g, at least 850 J / g, at least 900 J / g, at least 950 J / g, or at least 1000 J / g.

66. A yarn comprising the polypeptide according to any of claims 40-51 or the fibre according to any of claims 59-65.

67. A textile comprising the polypeptide according to any of claims 40-51, the fibre accordingto any of claims 59-65, or the yarn according to claim 66.

68. Use of the polypeptide according to any of claims 40-51, the fibre according to any ofclaims 59-65, the yarn according to claim 66, or the textile according to claim 67, in theproduction of a textile product of, wherein the textile product is selected from sportswear; materials for blast containment; materials for blade containment; textiles for parachutes; ropes; textiles for clothing; textiles for shoes; general medical textiles; wound dressings; resorbable and non-resorbable surgical sutures; resorbable and non-resorbable stents; guide-wires for surgery; biocompatible coatings for implanted medical devices; surgical meshes; and scaffolds for 3D tissue engineering.

69. A textile product comprising the polypeptide according to any of claims 40-51, the fibreaccording to any of claims 59-65, the yarn according to claim 66, or the textile according toclaim 67, wherein the textile product is selected from sportswear; materials for blastcontainment; materials for blade containment; textiles for parachutes; ropes; textiles for clothing; textiles for shoes; general medical textiles; wound dressings; resorbable and non- resorbable surgical sutures; resorbable and non-resorbable stents; guide-wires for surgery; biocompatible coatings for implanted medical devices; surgical meshes; and scaffolds for 3D tissue engineering.

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