Two beta-glycanase genes are clustered in Bacillus polymyxa: molecular cloning, expression, and sequence analysis of genes encoding a xylanase and an endo-beta-(1,3)-(1,4)-glucanase

Abstract

Two genes, xynD and gluB, encoding a xylanase and an endo-4-(1,3)-(1,4)-glucanase (lichenase) from Bacillus polymyxa have been cloned and expressed in Escherichia coli and Bacillus subtilis. A sequenced DNA fragment of 4,466 bp contains both genes, which are separated by 155 bp. The xynD and gluB genes encode proteins of 67.8 kDa (XYND) and 27 kDa (GLUB). Two peptides with molecular masses of 62 and 53 kDa appear in cell extracts of E. coli and culture supernatants of B. subtWis clones containing the xynD gene. Both peptides show xylanase activity in zymogram analysis. The XYND enzyme also shows Ot-L-arabinofuranosidase activity. The XYND peptide and the xylanase XYNZ from Clostridium thermocellum (0. Grepinet, M. C. Chebrou, and P. Beguin, J. Bacteriol. 170:4582-4588, 1988) show 64% homology in a stretch of about 280 amino acids.Plant cell walls are degraded by many enzymes that fall into two groups: cellulases (endo and exoglucanases) and hemicellulases (endoxylanases, arabinofuranosidases, etc.). Many bacteria, fungi, and yeasts show such activities, and one species can exhibit several activities of the two classes of enzymes (4, 11). The biotechnological importance of these microorganisms and their activities in food, paper, and other industries is great. The industrially important genus Bacillus is generally considered to be noncellulolytic. However, some species, such as B. polymyxa, show cellulase and/or hemicellulase activities (27). One B. polymyxa endo-1-(1,4)-glucanase (2) and two ,-glucosidases (15, 16) have been described, and their genes have been cloned and sequenced. There is another report of an endo-3-(1,3)-glucanase (laminarinase) in this species (12). Also, the existence of two endoxylanases (35) and one ,-xylosidase (28) from this species has been reported, and at least one of the endoxylanase genes (35) and the P-xylosidase (28) gene have been cloned. Here, we described the cloning, sequencing, and expression in Escherichia coli and B. subtilis of an endo-,-

New genes in the 170 region of the Bacillus subtilis genome encode DNA gyrase subunits, a thioredoxin, a xylanase and an amino acid transporter

“…The direction of transcription of xjnD is opposite to the majority of the genes in the region. The protein sequence showed strong similarities to endo-lY4-/l-xylanase D from B. pobmyxa (Gosalbes et al, 1991) and to endo-1,4-/lxylanases from Clostridit/m tbermacellum (Grepinet et al, 1988) and C. stercorarium (Sakka et a/., 1993).…”

Crystal structure of Bacillus licheniformis 1,3‐1,4‐β‐d‐glucan 4‐glucanohydrolase at 1.8 Å resolution

“…3.2.1.73) from different Bacillus strains have been cloned and sequenced [1][2][3][4][5][6][7]. These enzymes cleave fl-1,4-glycosidic bonds that are adjacent tofl-l,3-glycosidic bonds in mixed linked glucans.…”

Molecular and active-site structure of a Bacillus 1,3-1,4-beta-glucanase.

“…1A). The ,B-glucanases secreted from different Bacillus strains share significant sequence homology (10)(11)(12)(13)(14) and also with the enzymes from Clostridium thermocellum and from Fibrobacter succinogenes (15,16).…”