CLONING OF 2 HALOHYDRIN HYDROGEN-HALIDE-LYASE GENES OF CORYNEBACTERIUM SP STRAIN N-1074 AND STRUCTURAL COMPARISON OF THE GENES AND GENE-PRODUCTS

We cloned the genes from Corynebacterium sp. strain N-1074, for two halohydrin hydrogen-halidelyase isoenzymes (hheA and hheB), which are involved in the transformation of alpha, beta-halohydrin into the corresponding epoxide and the reverse reaction. The nucleotide sequences of 1057 base pairs including the hheA gene and of 1130 base pairs including the hheB gene were analyzed. The predicted amino acid sequence of the hheA gene product consisted of 244 residues, and the calculated molecular weight was 26,465. The hheB gene had two sets of potential ribosome binding site and a possible initiation codon, The predicted amino acid sequences of the gene products consisted of 235 and 227 residues, and the calculated molecular weights were 26,179 and 25,236, respectively. Site-directed mutagenesis experiments strongly suggested dual translational initiation in the hheB gene. Comparison of the predicted amino acid sequences for the hheA and hheB genes found significant homology only in the carboxyl terminal region. An analysis of the upstream regions of the both hhe genes suggested the presence of putative epoxide hydrolase genes, which might be involved in further degradation of epoxide compounds.