DNA encoding novel enzyme having D-serine synthase activity, method of producing the enzyme and method of producing D-serine by using the same

摘要

This invention relates to DNA encoding a novel enzyme having activity of synthesizing D-serine from formaldehyde and glycine, recombinant DNA constructed by integrating such DNA into a vector, a transformant transformed with the recombinant DNA, and a method for producing D-serine from formaldehyde and glycine with the use of the enzyme.

主权项

1. A method for producing D-serine, wherein D-serine is synthesized by allowing glycine to react with formaldehyde in the presence of a microorganism having activity of synthesizing D-serine from glycine and formaldehyde or a treated product thereof, wherein the microorganism is a transformant obtained by transforming a host cell, which is optionally a D-serine-deaminase-deficient microorganism, using recombinant DNA constructed by integrating DNA encoding a protein comprising the amino acid sequence of SEQ ID NO: 4, 6, or 8 or a protein comprising an amino acid sequence derived from the amino acid sequence of SEQ ID NO: 4, 6, or 8 by deletion, substitution, insertion, or addition of 1 to 5 amino acid residues and having enzyme activity of synthesizing D-serine from glycine and formaldehyde, the host cell being selected from the group consisting of Escherichia coli and yeasts, and the method comprising one or more of the following (i) to (iv) whereby formation of L-serine as a byproduct in a reaction solution is restrained such that L-serine accounts for 1.5 mol % or less relative to D-serine during the reaction:
(i) allowing a microorganism having activity of synthesizing D-serine from glycine and formaldehyde to be subjected to an organic solvent treatment or heat treatment or both; (ii) controlling formaldehyde concentration in a reaction solution a) to 2M or less in a case in which an organic solvent treatment or heat treatment or both are/is carried out by the method (i) above and b) to from 150 mM to 2M inclusive in a case in which an organic solvent treatment or heat treatment or both are/is not carried out; (iii) using, as a catalyst, a microorganism comprising an enzyme having activity of synthesizing D-serine from glycine and formaldehyde and lacking a L-serine synthase gene; and (iv) adding a microorganism comprising an enzyme having an L-serine deaminase activity to a reaction solution.