Recombinant Spider Silk Protein Solubility and Fiber Mechanics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current engineered spider silk proteins face challenges in achieving high solubility in water and scalable production, with previous methods resulting in fibers with poor mechanical properties due to incomplete or altered terminal domains and repetitive regions, and inadequate solubility.
Innovation Solution
A recombinant spider silk protein with a specific domain arrangement of (NT)-REP-CT, where the NT and CT domains are highly soluble and pH-responsive, allowing for biomimetic spinning and formation of fibers with improved mechanical properties, using a minispidroin design combining NT from E. australis MaSp1 and CT from A. ventricosus MiSp with a short repetitive region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recombinant spidroins are produced in bacteria, yeast or insect cells, then spider silk proteins can be obtained, but the proteins have low solubility in water and poor yields that prevent scalable production
Solution Approach 1:
The patent modifies the spidroin protein sequence by engineering the terminal domains (NT and CT) with specific amino acid compositions and structures that enhance solubility. The repetitive region is designed with optimized repeat units that maintain self-assembly capability while improving water solubility, enabling scalable production without requiring organic solvents.
Solution Approach 2:
The patent creates a composite protein structure combining engineered terminal domains with optimized repetitive regions. The NT domain is designed with high solubility characteristics while the CT domain is engineered to control self-assembly, creating a composite structure that achieves both high solubility and functional self-assembly properties for scalable fiber production.
2Ease of manufacture
If the repetitive region is engineered from iterated consensus repeats, then production is simplified, but the proteins differ significantly from natural spidroins and have poor mechanical properties
Solution Approach 1:
The patent applies different design strategies to different regions of the spidroin protein. The terminal domains (NT and CT) are engineered with specific sequences optimized for solubility and self-assembly control, while the repetitive region contains optimized repeat units that preserve the mechanical properties of natural silk. This local optimization allows simplified production while maintaining superior mechanical characteristics.
3Ease of manufacture
If solvents such as HFIP and formic acid are used to improve solubility, then recombinant spidroins become more soluble, but the solubility is far from the extreme solubility of spidroins in native dope (300-500 mg/ml)
Solution Approach 1:
The patent engineers the spidroin protein sequence to inherently possess high solubility characteristics through optimized amino acid composition in the terminal domains and repetitive regions. This eliminates the need for organic solvents like HFIP and formic acid, enabling the production of highly concentrated aqueous dopes (300-500 mg/ml) that match native spider silk dope concentrations, thus achieving both ease of manufacture and high protein concentration.
4Ease of manufacture
If terminal domains are modified or truncated to improve production, then manufacturing is easier, but the fibers lack the mechanical properties of native spider silk
Solution Approach 1:
The patent optimizes the terminal domain sequences through engineered amino acid modifications that maintain the functional integrity of NT and CT domains while improving solubility and self-assembly characteristics. The full-length terminal domains are preserved with optimized sequences that enable both ease of production and the formation of fibers with native-like mechanical properties including toughness and extensibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The recombinant spider silk proteins exhibit unprecedented solubility and form fibers with mechanical properties comparable to native spider silk, including high toughness and stability, surpassing previous artificial spider silk fibers in terms of strength and extensibility.
Implementation Method 1
when pH is lowered in the spinning duct, NT forms stable dimers, which locks the spidroins into large networks
Implementation Method 2
NT forms stable dimers
Implementation Method 3
decrease in pH resulted in that CT got destabilized, unfolded and turned into β-sheet amyloid-like fibrils
Implementation Method 4
CT got destabilized, unfolded and turned into β-sheet amyloid-like fibrils
Implementation Method 5
The structural conversion of CT is hypothesized to trigger the transition of the repetitive region into β-sheet conformation, in analogy with the nucleation phenomenon seen in amyloid fibril formation
Implementation Method 6
shear forces generated along the narrowing duct affect the spidroin terminal domains
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3d
AI summary
A recombinant spider silk protein, consisting of no more than 800 amino acids, comprising a set of domains arranged according to the formula (NT)-REP-CT, wherein: the optional NT-domain, if present, comprises a sequence of 100 to 160 amino-acid residues derived from the N-terminal domain of a spider silk protein; the REP-domain comprises a sequence of 30 to 600 amino acid residues derived from the repetitive segment of a spider silk protein; and the CT-domain comprises a sequence of 70 to 120 amino acid residues derived from the C-terminal domain of a spider silk protein selected from: a sequence of 72 to 110 amino acid residues derived from the C-terminal domain of a spider silk protein, wherein the sequence comprises at least 7 residues independently selected from K, R, E and D; a sequence having at least 85% identity to SEQ ID NO: 15 or any one of SEQ ID NO:s 62-65 or 67-73; and a sequence having at least 70% identity to SEQ ID NO: 64 or any one of SEQ ID NO:s 62-65 or 67-73, wherein the sequence comprises at least 7 residues independently selected from K, R, E and D. Solutions, polymers, uses and methods of manufacture thereof.