STRUCTURE OF THE GENE ENCODING BETA-1,3-GLUCANASE-B OF BACILLUS-CIRCULANS-WL-12

beta-1,3-Glucanases B (GLcB) and C (GlcC) are the major beta-1,3-gluca nases of Bacillus circulans WL-12 detected in the culture supernatant grown in beta-1,3-glucan-free medium. The gene (glcB) encoding GlcB wa s cloned into Escherichia coli and its nucleotide sequence was determi ned. The open reading frame of the glcB gene encodes a polypeptide of 412 amino acid residues. The N-terminal amino acid sequences of GlcB a nd GlcC purified from B. circulans culture supernatant were determined to be identical to each other and to the deduced sequence downstream of Ala-29. The N-terminal amino acid sequence, isoelectric point and e stimated size of the beta-1,3-glucanase produced by E. coli cells carr ying the cloned glcB gene agreed well with those of GlcB of B. circula ns WL-12. The N-terminal to central region of GlcB exhibited high sequ ence similarity to beta-1,3-glucanases of alkalophilic Bacillus AG-430 , GlcA1 of B. circulans WL-12 and the 87 kDa beta-1,3-glucanase H of B . circulans JAM1165. The C-terminal region of GlcB exhibited sequence similarity to the C-terminal regions of XlnA of Streptomyces lividans, beta-1,3-glucanases of Oerskovia xanthineolytica and Arthrobacter sp. YCWD3, and yeast lytic protease I of Rarobacter faecitabidus. Biochem ical and sequence data strongly suggested that GlcC detected in the cu lture supernatant of B. circulans WL-12 corresponded to the catalytic domain of GlcB generated by loss of a C-terminal region of GlcB.