Molecular cloning, expression and nucleotide sequence of the endo‐β‐1,3‐1,4‐d‐glucanase gene from Bacillus licheniformis Predictive structural analyses of the encoded polypeptide

Abstract

A Bacillus licheniformis gene coding for an endo-~-l,3-1,4-~-glucanase have been cloned in Escherichia coli and sequenced. The open reading frame contains a sequence of 731 bp, encoding a polypeptide of 243 amino acid residues, with a molecular mass of 27404 Da (24418 Da without the putative signal peptide), which corresponds to the enzyme we had previously isolated and characterized. The signal peptide is functional in E. coli. More than 60% of the endo-P-l,3-1,4-~-glucanase activity is extracellular or periplasmic. The polypeptide is highly similar to other reported Bacillus P-glucanases. Several structural predictive analyses (secondary structure, hydropathic plots, similarity with other related enzymes, etc.) have been performed. From these analyses we assign a tentative three-functional-domain structure for the enzyme (signal peptide, substrate binding and catalytic domains) and a putative lysozyme-like active site.Endo-P-l,3-1,4-~-glucanase is an enzyme that hydrolyzes mixed (1,3-1,4) linkage P-glucans from walls of starchy seed endosperm. /3-glucan is the principal cell wall component of barley endosperm and consists of glucose units joined by 8-1,4 and p-1,3 linkages. Endo-/l-1,3-1,4-~-glucanase hydrolyses 8-1,4 linkages adjacent to /3-1,3, yielding cellobiosyltriose and cellotriosyltetraose [l -31.In a previous paper we have reported the characterization and purification of an endo-fi-l,3-1,4-~-glucanase activity, lichenase, from Bacillu.~ licheniformis [4]. The enzyme is especially interesting for the brewing industry as P-glucans are the cause of problems in the filtration processes [5], and for broiler chick feedstuffs to improve digestibility [6]. The best characterized P-glucanases are those from genus Bacillus. Some genes of this genus, one from Fibrobacter succinogenes and one from barley aleurone, have been cloned and sequenced [7-141. In the present paper we describe the molecular cloning and sequencing of an endo-P-l,3-1,4-~-glucanase gene from B. lichenformis, the secondary structure prediction; hydropathic profile and sequence analyses. From the above, weCorrespondence to

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

“…At position 211 of the enzyme a tyrosine residue was identified (Fig. 1) where a serine was expected from the published sequence [6].…”

“…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).…”

Structure of the Clostridium thermocellum gene licB and the encoded β‐1,3‐1,4‐glucanase

“…Lloberas et al [6] detected some remote similarity between the region from Glu160 to Asp1 79 of B. licheniformis lichenase and the active site of egg-white lysozyme. However, the sequence similarities between the Bacillus enzymes and lysozymes are not generally conserved within bacterial lichenases and their relevance is therefore questionable.…”

“…Commercial enzymes have been produced mainly from bacteria of the genus Bacillus [l]. In order to improve enzyme production and activity by genetic manipulation, genes encoding /?-1,3-1,4-glucanases have been cloned and sequenced from Bacillus subtilis [2, 31, B. amyloliquefuciens [4], B. macerans [5], B. lichenijiormis [6], F. succinogenes [7] and barley [8]. Thermostable lichenases which are active at the elevated temperatures employed in the malting process (50-70°C) are of particular interest.…”