Sucrose synthase for catalytic production of NDP-Glc and recombinant gene of sucrose synthase

Abstract

The invention discloses a sucrose synthase for catalytic production of NDP-Glc and a recombinant gene of the sucrose synthase. The substrate Reb A / Reb D catalyzed by the sucrose synthase has poor solubility at low temperature, and the reaction efficiency can be obviously accelerated when the substrate Reb A / Reb D catalyzes and produces Reb D / Reb M in a high-temperature environment, so that the sucrose synthase also needs to be subjected to catalytic reaction at high temperature, and NDP-Glc is provided for the production of Reb D / Reb M in real time. Compared with wild type sucrose synthase, the sucrose synthase variant disclosed by the invention has the advantage that the thermal stability and the enzyme activity are obviously improved. The enzyme activity of the wild sucrose synthase is only about 29% of the highest value in a high-temperature environment of 70 DEG C, and the enzyme activity of the sucrose synthase mutant in the environment of 70 DEG C is more than 50U / mg. Therefore, the sucrose synthase variant disclosed by the invention is suitable for being used as a biocatalyst and is used for large-scale production of a sweetening agent rebaudioside D / rebaudioside M with better taste.

Description

Technical Field

[0001] The present invention relates to the field of bioengineering, and more particularly to a sucrose synthase for catalyzing the production of NDP-Glc and a recombinant gene thereof. Background Art

[0002] Stevioside, also known as steviol glycoside, boasts high sweetness (300-450 times that of sucrose) and low caloric value (1 / 300 of sucrose). It is a natural sucrose substitute and is known as the "world's third most potent sugar source." Stevioside is extracted from the stevia leaf, and manufacturers primarily extract stevioside (STV) and rebaudioside A (Reb A). However, STV and Reb A have a distinct bitterness and licorice aftertaste, which significantly limits the use of steviol glycosides as sweeteners in food.

[0003] Research has found that rebaudioside D (Reb D) retains the advantages of stevia, including high sweetness and low caloric value, while exhibiting minimal bitterness and licorice aftertaste. Rebaudioside M (Reb M) maintains the advantages of stevia, including high sweetness and low caloric value, while exhibiting virtually no bitterness or licorice aftertaste. Both Reb D and Reb M offer superior taste to Reb A. However, large-scale production of Reb D and Reb M faces significant bottlenecks: Reb D accounts for less than 2% of stevia leaves, and Reb M accounts for less than 1%. Plant-based extraction of Reb D and Reb M is therefore expensive. Therefore, biocatalytic synthesis of Reb D and Reb M is currently a popular production method in the industry. Glycosyltransferases catalyze the transfer of glycosyl groups from NDP-Glc to Reb A, producing Reb D and / or Reb M. However, NDP-Glc is expensive. If it is used as a raw material for producing Reb D or Reb M, the production cost of Reb D or Reb M will be high. Therefore, how to reduce the production cost of NDP-Glc is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In view of the shortcomings of the prior art, one of the objectives of the present invention is to provide a sucrose synthase variant with an optimum reaction temperature of about 70°C and an enzyme activity of more than 50 U / mg.

[0005] To achieve the above object, the present invention provides the following technical solutions: A heat-resistant sucrose synthase, whose wild-type sequence is shown in SEQ ID NO.1. This wild-type sucrose synthase sequence is derived from the protein sequence library NIH: WP_291511759.1. Using the Lésign platform, sequence design was carried out on the wild-type sucrose synthase, and finally the optimal enzyme variant at the computational level was obtained.

[0006] A sucrose synthase for catalyzing the production of NDP-Glc, the sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent, and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+S187R+L176S+S526R+T727R+V126F.

[0007] The second object of the present invention is to provide another sucrose synthase variant with an optimal reaction temperature of about 70°C and an enzyme activity of more than 55 U / mg.

[0008] To achieve the above object, the present invention provides the following technical solutions: A sucrose synthase for catalyzing the production of NDP-Glc, the sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent, and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+T191I+A164E+S652R+Q108R+D463H.

[0009] The third object of the present invention is to provide another sucrose synthase variant with an optimal reaction temperature of about 70°C and an enzyme activity of more than 55 U / mg.

[0010] To achieve the above object, the present invention provides the following technical solutions: A sucrose synthase for catalyzing the production of NDP-Glc, the sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent, and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+T199M+E613V+A164E+A358P+D455E+V126F.

[0011] The fourth object of the present invention is to provide another sucrose synthase variant with an optimal reaction temperature of about 70°C and an enzyme activity of more than 55 U / mg.

[0012] To achieve the above object, the present invention provides the following technical solution: a sucrose synthase for catalytic production of NDP-Glc, the sucrose synthase being based on the wild-type sucrose synthase described in SEQ ID NO:1 and mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+S526R+S652R+H64R+D488N+I2F+D455E+A164E+V126F+H442Y.

[0013] A fifth object of the present invention is to provide another sucrose synthase variant with an optimum reaction temperature of about 70 °C and an enzyme activity of more than 55 U / mg.

[0014] To achieve the above object, the present invention provides the following technical solution: a sucrose synthase for catalytic production of NDP-Glc, the sucrose synthase being based on the wild-type sucrose synthase described in SEQ ID NO:1 and mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+H64R+T191I+S526R+D455E+D463H+L416W+H442Y.

[0015] A sixth object of the present invention is to provide another sucrose synthase variant with an optimum reaction temperature of about 70 °C and an enzyme activity of more than 55 U / mg.

[0016] To achieve the above object, the present invention provides the following technical solution: a sucrose synthase for catalytic production of NDP-Glc, the sucrose synthase being based on the wild-type sucrose synthase described in SEQ ID NO:1 and mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+L176S+L176Q+T199M+R208P+S368P+S187R+H442Y+Q108R+E414Q+H446Y.

[0017] A seventh object of the present invention is to provide another sucrose synthase variant with an optimum reaction temperature of about 70 °C and an enzyme activity of more than 55 U / mg.

[0018] To achieve the above object, the present invention provides the following technical solution: a sucrose synthase for catalytic production of NDP-Glc, the sucrose synthase is based on the wild-type sucrose synthase described in SEQ ID NO:1 as the parent, and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+S368P+L416W+D455E+H699L+A358P+H446Y+I2F+L163R.

[0019] An eighth object of the present invention is to provide another sucrose synthase variant with an optimal reaction temperature of about 70 °C and an enzyme activity of more than 55 U / mg.

[0020] To achieve the above object, the present invention provides the following technical solution: a sucrose synthase for catalytic production of NDP-Glc, the sucrose synthase is based on the wild-type sucrose synthase described in SEQ ID NO:1 as the parent, and is mutated with the following mutation set:

[0021] S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+D488H+T727R+H442Y+V126F+T199M+E613V+A358P+S652R+A164E+S187R.

[0022] A ninth object of the present invention is to provide a genetic material capable of expressing the above sucrose synthase variant.

[0023] To achieve the above object, the present invention provides the following technical solution: a recombinant genetic material of a sucrose synthase, a DNA or RNA capable of expressing the above sucrose synthase.

[0024] A tenth object of the present invention is to provide a recombinant strain capable of expressing the above sucrose synthase variant.

[0025] To achieve the above object, the present invention provides the following technical solution: a recombinant strain of a sucrose synthase, including a recombinant genetic material capable of expressing the above sucrose synthase.

[0026] Compared with the prior art, the advantages of the present invention are as follows: The substrates Reb A / Reb D catalyzed by this enzyme have poor solubility at low temperatures, and the catalytic production of Reb D / Reb M in a high-temperature environment can significantly accelerate the reaction efficiency. Therefore, sucrose synthase also needs to carry out catalytic reactions at high temperatures, so as to provide NDP-Glc in real time for the production of Reb D / Reb M. Compared with wild-type sucrose synthase, the thermal stability and enzyme activity of the sucrose synthase variant of the present invention have been significantly improved. At a high temperature of 70 °C, the enzyme activity of wild-type sucrose synthase is only about 29% of the highest value, and the enzyme activity of the sucrose synthase mutant at 70 °C is above 50 U / mg. Therefore, the sucrose synthase variant of the present invention is suitable as a biocatalyst for the large-scale production of the sweeter sweeteners rebaudioside D / rebaudioside M. Detailed implementation mode

[0027] The term "recombinant gene" refers to DNA or RNA that can express the sucrose synthase of the present invention. Generally, the recombinant gene is initially synthesized in vitro by the solid-phase phosphoramidite triester method or the TdT biosynthesis method or other suitable techniques known in the art. After having the template sequence, it can be amplified by PCR or other suitable techniques known in the art. After having the recombinant strain, it can be further amplified on a large scale by culturing the strain. In some embodiments, the recombinant gene may also include restriction site residual sequences, other accessory elements, such as control elements (such as promoters, etc.), labeling substances (such as fluorescent labels, etc.), and other sequences that do not affect the expression of the target gene.

[0028] The term "cloning scar" refers to a promoter sequence where protein expression depends on the transcription of the initial messenger ribonucleotide (mRNA), followed by a ribosome-binding site (RBS) that attracts the translation machinery, followed by a signal peptide sequence that helps transport the protein to the periplasm. The mature protein is usually cloned after the signal peptide and is cleaved from the signal peptide by signal peptidase when passing through the membrane. However, when cloning a construct after the signal peptide, restriction endonucleases usually require specific sequences to cut DNA, which leaves a cloning scar after the signal peptide sequence.

[0029] The term "signal peptide" refers to a short peptide (usually 16-30 amino acids long) present at the N-terminus of most newly synthesized proteins that are destined to enter the secretory pathway. It can also be referred to as a signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequence, or leader peptide. The signal peptide is usually cleaved from the protein by signal peptidase.

[0030] Whether it is a cloned scar, signal peptide or other elements in the recombinant gene, it does not affect the realization of the function of sucrose synthase. Therefore, if the amino acid sequence of the finally obtained protein differs from the amino acid sequence disclosed in the present invention only by the amino acid sequence corresponding to the above DNA sequence, it still falls within the protection scope of the present invention.

[0031] The term "signal peptide cleavage site" refers to a dipeptide between which signal peptidase cleaves the signal peptide from the mature protein. In most (but not all) cases, the dipeptide is Ala-Ala. The signal peptide cleavage site can be calculated using algorithms such as SignalP 4.1, which is available online at http: / /

[0032] / / www.cbs.dtu.dk / services / SignalP / (Center for Biological Sequence Analysis, Technical University of Denmark).

[0033] The term "promoter" refers to a DNA region that initiates the transcription (writing to mRNA) of a specific gene. The promoter is usually located near the transcription start site of the gene, on the same strand and upstream of the DNA (pointing to the 5' region of the sense strand). The promoter can be inducible, which means that the expression of the gene operably linked to the promoter can be turned on by the presence of an inducer substance. Alternatively, the promoter can be constitutive, i.e., it is not regulated by any inducer substance.

[0034] The abbreviation "RBS" refers to the ribosome-binding site, or the binding site of the ribosome. This is the sequence of nucleotides upstream of the start codon of the mRNA transcript, which is responsible for recruiting ribosomes during the initiation of protein translation.

[0035] The term "expression" refers to the process of DNA being transcribed into messenger RNA (mRNA) and then translated into protein. To achieve the smooth expression and screening of sucrose synthase, the above-mentioned signal peptide, promoter, and RBS may be introduced into the recombinant gene. Therefore, some corresponding peptide segments may remain on the expressed sucrose synthase protein. These peptide segments do not affect the function of sucrose synthase. Therefore, even if the above-mentioned peptide segments are present in the product, as long as the amino acid sequence of the main part is the same as the sequence of the present invention, the product is still an infringing product.

[0036] The term "expression vector" has the ability to incorporate and express a heterologous polynucleotide fragment in a host cell. Many prokaryotic and eukaryotic expression vectors are commercially available. Selecting a suitable expression vector is within the knowledge of those skilled in the art.

[0037] The term "chassis cell" refers to a suitable host vector for expressing the DNA of the present invention. The host can include any organism capable of containing and expressing the nucleic acids or genes disclosed herein, but is not limited thereto. The chassis cell can be prokaryotic or eukaryotic, single-celled or multi-cellular, including mammalian cells, plant cells, fungi, etc. According to the prior art, those skilled in the art can achieve the heterologous expression of the recombinant DNA of the present invention in different disclosed chassis cells by adjusting parameters through a limited number of experiments. The chassis cell can be selected from at least one of Escherichia coli, Pichia pastoris, Saccharomyces cerevisiae, Hansenula anomala, Candida sp., Rhodotorula sp., Bacillus sp., Escherichia sp., Salmonella sp., Clostridium sp., Streptomyces sp., Staphylococcus sp., Neisseria sp., Shigella sp. The present invention only lists the types of chassis cells and does not constitute a limitation on the types of chassis cells. The chassis cell is preferably Escherichia coli, and suitable Escherichia coli strains (including many other strains) include BL21(DE3), C600, DH5αF′, 1113101, JM83, JM101, JM103, JM105, JM107, JM109, JM110, MC1061, MC4100, MM294, NM522, NM554, TGI, χ1776, XL1-Blue and Y1089 + etc. All of the above Escherichia coli strains are commercially available strains.

[0038] The present invention will be further described in detail below in conjunction with the embodiments.

[0039] Example 1

[0040] Protein is the material basis of life and an important component of human cells and tissues. All important components in the human body require the participation of proteins, and it plays a very important role in the life activities of cells and organisms. It can be said that without proteins, there is no life. There are a very large number of protein types in the human body, and their functions are also different. Some form human tissues, some can provide energy, some can participate in material metabolism and transport, some promote growth and development, and regulate immune functions. Different proteins undertake different responsibilities and functions, and their functions are determined by the structure of the protein. And the 3D structure of the protein is determined by the amino acid sequence of the protein. Therefore, the design of proteins depends on the correspondence between structure and sequence. To design proteins with specific functions, sequences that conform to the function structure need to be designed. Understanding and designing proteins is of great significance for promoting the innovation and progress of biology and medicine.

[0041] Designing a protein sequence for a specific function is a very difficult task. It is difficult to predict what structure and function the designed sequence will finally present. Moreover, the sample space of protein sequences with a fixed length is also extremely large. To complete the above work, Liwen Institute has developed a protein design platform based on deep learning algorithms - Lésign. This platform realizes functions such as protein structure prediction, sequence design, and result evaluation. Each functional module collaborates through interfaces to form a computational pipeline integrating prediction, design, and evaluation.

[0042] Using the Lésign platform, sequence design was carried out on wild-type sucrose synthase (the amino acid sequence is shown in SEQ ID NO.1), and finally the computationally optimal enzyme variant was obtained.

[0043] 1. Preparation of Sucrose Synthase

[0044] 1.1 Construction of Recombinant Cells:

[0045] The nucleotide sequences of the target genes were all synthesized by Beijing Tsingke Biotechnology Co., Ltd., and the nucleotide sequence of sucrose synthase was inserted into the expression vector. Specifically, it was inserted into the plasmid pET28a(+) to obtain the corresponding plasmid. Subsequently, the synthesized plasmid was transferred into the chassis cell (E.coli BL21(DE3)), thereby constructing an Escherichia coli strain containing the plasmid. There are many other available plasmids and chassis cells in the prior art, and this example only provides a specific scheme.

[0046] 1.2 Expression and Purification of Sucrose Synthase:

[0047] The recombinant bacteria were inoculated into a shake flask at 1% and cultured overnight, and then inoculated into a fermenter at 1%. The fermenter contained liquid TB medium and was cultured until the OD 600 value was about 6.0, then IPTG was added to a concentration of 100 μM, and the temperature was reduced to 16 degrees and cultured overnight. After overnight culture, the cells were collected by centrifugation at 4000g for 10 min and washed with 0.1M PB buffer (pH 7.0). Next, the cells were disrupted by sonication, and then centrifuged at 12000 rpm for 1 h. The supernatant was the crude enzyme solution. There are many other available methods for inducing the expression of recombinant bacteria in the prior art, and this example only provides a specific scheme.

[0048] The crude enzyme solution was purified by nickel column. The crude enzyme solution was eluted under different elution conditions to obtain the target protein. According to the prior art, those skilled in the art can adjust the parameters through a limited number of experiments to achieve the purification of sucrose synthase, and specific descriptions are not provided here. There are many other available methods for purifying sucrose synthase in the prior art, and this example only provides a specific scheme.

[0049] The wild-type sucrose synthase (ZTM, SEQ ID NO: 1) and sucrose synthase variants were heterologously expressed and purified according to the above-mentioned method for preparing sucrose synthase. The obtained sucrose synthase and mutants were verified by gel electrophoresis (SDS-PAGE) to confirm that the sizes of the sucrose synthase and mutants were consistent with the expectations.

[0050] 2. Enzyme activity assay:

[0051] 3.1 Catalytic reaction system: The total volume of the enzyme activity assay reaction system was 0.5 mL, which included 0.5 M sucrose as the substrate concentration, 0.005 mg / mL sucrose synthase or variant concentration, 10 mM uridine diphosphate (UDP), and the volume was made up to 0.5 mL with 0.1 M citric acid-sodium citrate buffer (pH 5.0).

[0052] 3.2 Method for measuring enzyme activity at different reaction temperatures:

[0053] The reaction was carried out according to the catalytic reaction system in 3.1. The reaction temperatures for the wild-type sucrose synthase were 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, and 70°C, and the reaction temperatures for the sucrose synthase variant were 55°C, 60°C, 65°C, 70°C, 75°C, and 80°C. The reaction time was 1 h for all, and the reaction conditions were 1000 rpm / min.

[0054] After the reaction ended, 100 μL of the reaction solution was mixed with 200 μL of DNS, boiled in a boiling water bath for 5 min to terminate the reaction and cooled in running water. Then, 900 μL of ddH₂O was added, and after mixing, 200 μL was taken for detection by a microplate reader (540 nm). The linear relationship between OD 540nm and fructose concentration was obtained by preparing a standard curve. Then, based on the measured OD of the reaction solution 540nm the concentration of fructose in the reaction solution was calculated.

[0055] Definition of enzyme activity: The amount of enzyme required to catalyze the formation of 1 μM fructose per minute. The enzyme activities of the measured wild-type sucrose synthase and sucrose synthase variants are shown in Tables 1 - 9:

[0056] Table 1 Enzyme activities of wild-type sucrose synthase at different reaction temperatures

[0057]

[0058]

[0059] Table 2 Enzyme activities of sucrose synthase variant ZTM-2 at different reaction temperatures

[0060]

[0061] Table 3 Enzyme Activity of Sucrose Synthase Variant ZTM-3 at Different Reaction Temperatures

[0062]

[0063] Table 4 Enzyme Activity of Sucrose Synthase Variant ZTM-4 at Different Reaction Temperatures

[0064]

[0065] Table 5 Enzyme Activity of Sucrose Synthase Variant ZTM-5 at Different Reaction Temperatures

[0066]

[0067]

[0068] Table 6 Enzyme Activity of Sucrose Synthase Variant ZTM-6 at Different Reaction Temperatures

[0069]

[0070] Table 7 Enzyme Activity of Sucrose Synthase Variant ZTM-7 at Different Reaction Temperatures

[0071]

[0072] Table 8 Enzyme Activity of Sucrose Synthase Variant ZTM-8 at Different Reaction Temperatures

[0073]

[0074] Table 9 Enzyme Activity of Sucrose Synthase Variant ZTM-9 at Different Reaction Temperatures

[0075]

[0076] As can be seen from Tables 1-9, the optimal reaction temperature of wild-type sucrose synthase is about 55 °C, and its thermal stability conforms to the general high-temperature situation. However, when the reaction temperature reaches 70 °C, the enzyme activity is only about 29% of the highest value, and it cannot be applied to the production environment with a reaction temperature of 70 °C. After sequence modification of the wild-type sucrose synthase of the present invention, the thermal stability of the obtained sucrose synthase mutant is significantly improved, and its optimal reaction temperature is 70 °C. At the same time, the enzyme activity of the sucrose synthase mutant is also significantly increased. The enzyme activity of the wild-type sucrose synthase at the optimal reaction temperature is only 11.134 U / mg, and the enzyme activity of the sucrose synthase mutant in the 70 °C environment is above 50 U / mg, which is suitable for industrial production.

[0077] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A sucrose synthase for catalyzing the production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+S187R+L176S+S526R+T727R+V126F.

2. A sucrose synthase for catalyzing the production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+T191I+A164E+S652R+Q108R+D463H.

3. A sucrose synthase for catalyzing the production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+T199M+E613V+A164E+A358P+D455E+V126F.

4. A sucrose synthase for catalyzing the production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+S526R+S652R+H64R+D488N+I2F+D455E+A164E+V126F+H442Y.

5. A sucrose synthase for catalytic production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+H64R+T191I+S526R+D455E+D463H+L416W+H442Y.

6. A sucrose synthase for catalytic production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+L176S+L176Q+T199M+R208P+S368P+S187R+H442Y+Q108R+E414Q+H446Y.

7. A sucrose synthase for catalytic production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+S368P+L416W+D455E+H699L+A358P+H446Y+I2F+L163R.

8. A sucrose synthase for catalytic production of NDP-Glc, characterized in that The sucrose synthase uses the wild-type sucrose synthase described in SEQ ID NO:1 as the parent and is mutated with the following mutation set: S49P+T103P+G112R+L163P+L176R+A608P+D53R+G189P+V281W+D488H+T727R+H442Y+V126F+T199M+E613V+A358P+S652R+A164E+S187R.

9. A recombinant genetic material of sucrose synthase, characterized in that DNA or RNA capable of expressing the sucrose synthase according to any one of claims 1 to 8.

10. A recombinant strain of sucrose synthase, characterized in that Recombinant genetic material comprising the sucrose synthase according to claim 9.

Images