Super-heat-resistant xylanase XynGold and gene and application
A xylanase and super heat-resistant technology, applied in the field of genetic engineering, can solve the problems of loss of activity, low enzyme specific activity and high production cost, and achieve the effects of increasing expression, increasing enzyme activity and improving activity.
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Embodiment 1
[0038] This example is used to illustrate the site-directed mutagenesis of xylanase gene.
[0039] Based on the xylanase gene xyn (SEQ ID NO: 4), the asparagine at position 68 in the original xylanase Xyn was mutated to glutamine (N68Y) by site-directed mutagenesis technology, and the glutamine at position 96 was mutated Amino acid was mutated to tryptophan (E96W). The xylanase obtained after point mutation (N68Y, E96W) is XynGold (SEQ ID NO: 1). The specific implementation steps include:
[0040] (1) The N68Q mutation was introduced into xylanase Xyn (SEQ ID NO: 2) by overlapping extension PCR technique. Using the xyn10B gene as a template, primers NQF1 (SEQ ID NO: 5, 5'-GAATTCAATGAAAATATTACCTTCTGTG-3') and NQR1 (SEQ ID NO: 6, 5'-GTATCCCACTTCATCTGGTTCTCAGGGGTCAGGATG-3') were used to amplify the first half of the xyn gene nqF1 and primers NQF2 (SEQ ID NO: 7, 5'-GTATCCCACTTCATCTGGTTCTCAGGGGTCAGGATG-3') and NQR2 (SEQ ID NO: 8, 5'-GCGGCCGCCTCATTTTCTTTCTTCTATC-3') were used to a...
Embodiment 2
[0045] This example is used to illustrate the optimization of the codons of the xylanase gene to obtain the gene xyngold.
[0046] In this example, based on the amino acid sequence of the mutated xylanase, the nucleotide sequence of the xylanase gene was artificially redesigned using DNA 2.0 software. Specifically include: compared with the original xylanase gene (SEQ ID NO: 4), high-frequency codons are used to replace low-frequency codons; the complexity and minimum free energy of the secondary structure of the mRNA encoded by the gene are reduced ( figure 2 ). The xyngold sequence of the xylanase gene was designed with the aid of computer, and the xyngold fragment of the xylanase gene was obtained by artificial synthesis.
[0047] In this embodiment, according to the amino acid sequence of xylanase, a brand-new xylanase gene sequence is artificially designed, and the xylanase gene fragment is obtained by artificial synthesis, and its base sequence is as SEQ ID NO: 3 and...
Embodiment 3
[0050] This example is used to illustrate the construction of xyngold recombinant expression strain of xylanase gene.
[0051] (1) Restriction sites EcoR I and Not I were added to both ends of the xyngold xylanase gene, and digested by EcoRI and Not I; similarly, the vector pPICZαA was digested by EcoRI and Not I. Among them, the enzyme digestion system is: 3mg DNA, 10UEcoR I, 10U Not I, 20μL of Buffer H and water to make up to 300μL volume, and enzyme digestion at 37°C for 4h. The result is as Figure 3A As shown (in the figure: M is DL5000 DNA Marker, lane 1 is the pPICZαA recombinant expression vector after enzyme digestion; lane 2 is the xyngold fragment after enzyme digestion; it can be seen from the figure that the sizes of pPICZαA and xyngold fragments are 3.7kb and 1.0kb respectively Left and right, in line with reality.
[0052] (2) Ligate the xyngold fragment of the xylanase gene and the pPICZαA fragment through T4 DNA ligase to obtain the pPIC-xyngold recombinant ...
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