Method for producing L-piperidinecarboxylic acid by mixed bacteria fermentation
A technology of pipecolinic acid and mixed bacteria, applied in the field of fermentation, can solve the problems of high construction difficulty and poor stability
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Embodiment 1
[0040] Example 1: Construction of a recombinant plasmid expressing lysine cyclizing deaminase.
[0041] Cloning is from S. pristinaespiralis (ATCC25486) lysine cyclizing deaminase gene (SpLCD) (gene is synthesized by Supkin Company, its amino acid sequence is shown in SEQ ID NO.3, and its nucleotide sequence is shown in SEQ ID NO .4.) Add XhoI and NcoI restriction sites at both ends, and insert the gene fragment into the corresponding restriction sites of the expression vector pET28a by double restriction digestion and ligation, and place it under the control of the T7 promoter to obtain The recombinant plasmid pET28a-SpLCD was obtained.
Embodiment 2
[0042] Example 2: Modification of lysine cyclizing deaminase Ile61.
[0043] By analyzing the structure of SpLCD, the bottleneck amino acid site Ile61 in the process of substrate binding and product release was found. From figure 1 It can be seen in b that the distance between Ile61 and Asp236 is the narrowest in the entire channel, which becomes the bottleneck that restricts the substrate small molecule lysine to enter the active center. From figure 2 a It can be seen that Ile61 and NAD + The distance between them causes a large steric hindrance at the product release site 1, which becomes a bottleneck that restricts the product small molecule L-piperidinecarboxylic acid from leaving the active center. Through whole plasmid PCR and saturation mutation screening, the optimal mutant Val61-SpLCD and recombinant plasmid pET28a-Val61-SpLCD were obtained.
Embodiment 3
[0044] Example 3: Modification of lysine cyclizing deaminase Ile94.
[0045] By analyzing the structure of SpLCD, the bottleneck amino acid site Ile94 in the process of substrate binding and product release was found. From figure 2 As can be seen in b, Ile94 and NAD + The distance between them causes a large steric hindrance at the product release site 2, which becomes a bottleneck that restricts the product small molecule L-piperidinecarboxylic acid from leaving the active center. The optimal mutant strain Val94-SpLCD and recombinant plasmid pET28a-Val94-SpLCD were obtained by whole plasmid PCR and saturation mutation screening.
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