Abstract
Two isozyme genes of glucose dehydrogenase, gdhI and gdhII, were isolated from Bacillus megaterium IAM1030, and their nucleotide sequences were identified. Each gene has an open reading frame of 783 base pairs available to encode a peptide of 261 amino acids. There are two more open reading frames, orf1 and orf2, upstream from gdhI; orf1 consists of 684 base pairs available to encode a peptide of 228 amino acids, and orf2 consists of 858 base pairs available to encode a peptide of 286 amino acids. The nucleotide sequence of orf2 seems to be similar to orfX in the gdh operon of B. subtilis. Upstream of orf2, as well as that of orfX, there is a probable promoter sequence very similar to the consensus promoter sequence recognized by B. subtilis RNA polymerase containing the sigma factor σ G, a new class of sporulation-specific promoters. Downstream from the coding region of orf2, no transcriptional termination signal is found, and soon after orf2, there is a ribosomal-binding sequence followed by the coding region of gdhI. Therefore, orf2 and gdhI seem to form an operon similar to the orfX-gdh operon of B. subtilis, and be transcribed during sporulation as a polycistronic message. In the upstream regions of gdhII and orfI, on the other hand, there are probable promoter sequences homologous to the postulated consensus promoter sequence recognized by B. subtilis RNA polymerase containing the sigma factor σ A. Both gdhI and gdhII are expressed in Escherichia coli cells. The phylogenic relationships among glucose dehydrogenase genes including gdhI and gdhII are also discussed.
Published Version
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