Structure of the 87-kDa beta-1,3-glucanase gene of Bacillus circulans IAM1165 and properties of the enzyme accumulated in the periplasm of Escherichia coli carrying the gene.

The nucleotides of a gene for the extracellular 87-kDa beta-1,3-glucanase of Bacillus circulans IAM1165 and its flanking regions were sequenced. The sequence showed an open reading frame for 877 amino acids, which corresponds to a precursor of the beta-1,3-glucanase. The coding region of 2631 bp is flanked by putative promoter and transcription terminator sequences. The signal peptide was considered to be consisted of 38 amino acids. The amino acid sequence of the mature enzyme composed of 839 amino acids showed high homology to that of the enzyme from B. circulans WL-12, although these enzymes are different in their sizes. A catalytic domain of the enzyme was estimated central region of the sequence on the basis of comparison of amono acid sequences of beta-1,3- or beta-1,3:1,4-glucanases. Properties of the periplasmic enzyme produced in Escherichia coli carrying the gene were identical with those of the extracellular enzyme produced by B. circulans IAM1165.