Alleles of the mtK gene from coryneform bacteria

摘要

Replicable DNA sequence (I) derived from coryneform bacteria, coding for an S-adenosylmethionine synthetase polypeptide with an amino acid sequence in which valine at position 200 or isoleucine at position 322 of a defined sequence (SEQ ID No.2) is replaced by another proteinogenic amino acid, is new : Independent claims are also included for: (1) plasmid vectors containing (I); (2) coryneform bacteria containing (I); (3) bacteria containing a vector as above; (4) isolated coryneform bacteria containing nucleic acid sequences coding for a polypeptide as above which is 4 amino acids longer than the wild type protein and has the sequence Ala-Gln-Pro-Ser-Ser-Cys-Pro-Lys-Asn-Leu-Met at positions 401-411; (5) producing L-methionine or animal feed additives containing L-methionine by culturing coryneform bacteria in which alleles of the endogenous metK gene are overexpressed under conditions suitable for forming the metK gene product S-adenosylmethionine synthetase and isolating the L-methionine or animal feed additive from the culture broth; (6) producing L-methionine or animal feed additives containing L-methionine by culturing coryneform bacteria having an endogenous nucleic acid sequence of type (I), enriching L-methionine in the culture broth and isolating the L-methionine or animal feed additive from the culture broth.