Abstract

The nucleotide sequence of the ?gIII(A) gene, encoding the extracellular ?-1,3-glucanase II(A) (?gIII(A)) of the yeast-lytic actinomycete Oerskovia xanthineolytica LL G109, was determined. Sequence comparison shows that the ?gIII(A) enzyme has over 80% identity to the ?gIII isoenzyme, an endo-?- 1,3-glucanase having low yeast-lytic activity secreted by the same bacterium. The ?gIII(A) enzyme lacks a glucan- or mannan-binding domain, such as those observed in ?-1,3-glucanases and proteases having high yeast/fungus-lytic activity. It can be included in the glycosyl hydrolase family 16. Gene fusion expression in Bacillus subtilis DN1885 followed by preliminary characterization of the recombinant gene product indicates that ?gIII(A) has a p1 of 3.8 to 4.0 and is active on bOth laminarin and curdlan, having an acid optimum pH activity (ca. 4.0).