Synthesis and secretion of a Bacillus circulans WL-12 1,3-1,4-beta-D-glucanase in Escherichia coli

Abstract

The synthesis and secretion of a 1,3-1,4-beta-D-glucanase were studied in different strains of Escherichia coli transformed with plasmids carrying the Bacillus circulans WL-12 1,3-1,4-beta-D-glucanase structural gene. This gene (named BGC) is contained within a 1.9-kilobase BamHI-HindIII fragment and directs the synthesis in E. coli of an enzyme that specifically degrades lichenan. Only one active form of the enzyme was found when the gene was expressed in different E. coli strains. The electrophoretic pattern of this protein showed a molecular weight that was approximately the same as that of the mature beta-glucanase secreted from B. circulans WL-12, suggesting that the processing of this protein may be similar in both species. As deduced from maxicell experiments, the Bacillus parental promoter directs the synthesis in E. coli. Pulse-chase experiments showed that the protein may be cotranslationally processed.