SEQUENCE-ANALYSIS OF THE GENE FOR AND CHARACTERIZATION OF D-ACETOIN FORMING MESO-2,3-BUTANEDIOL DEHYDROGENASE OF KLEBSIELLA-PNEUMONIAE EXPRESSED IN ESCHERICHIA-COLI

Analysis of the nucleotide sequence of the meso-2,3-butanediol dehydro genase (D-acetoin forming) (BDH) gene of Klebsiella pneumoniae IAM1063 revealed that it contains an open reading frame of 768 bp encoding a polypeptide of 256 amino acid residues with a molecular weight of 26,5 91 Da. The amino acid sequence deduced from the nucleotide sequence of the BDH gene is consistent with the amino-terminal and carboxyl-termi nal amino acid sequences, amino acid composition, and molecular weight of purified BDH. The amino acid sequences of BDHs from K. pneumoniae IAM1063 and Klebsiella terrigena VTT-E-74023 showed 92.9% homology in the first 196 amino acid residues, but no homology elsewhere. Moreover , the BDH of K. pneumoniae IAM1063 was 15 amino acid residues longer t han that of K. terrigena VTT-E-74023. The characteristics of the BDH f rom Escherichia coli JM109/pBUD119 (containing the meso-BDH gene) coin cided with that of the BDH from the gene source strain (K. pneumoniae IAM1063). Furthermore, the BDHs from K. pneumoniae IAM1063 and K. terr igena VTT-E-74023 showed similar catalytic properties. This suggests t hat the downstream of Gln at position 196 in the amino acid sequence i s unrelated to BDH activity.