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The nucleotide sequence of the ␤glII A gene, encoding the extracellular ␤-1,3-glucanase II A (␤glII A ) of the yeast-lytic actinomycete Oerskovia xanthineolytica LL G109, was determined. Sequence comparison shows that the ␤glII A enzyme has over 80% identity to the ␤glII isoenzyme, an endo-␤-1,3-glucanase having low yeast-lytic activity secreted by the same bacterium. The ␤glII 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 ␤glII A has a pI of 3.8 to 4.0 and is active on both laminarin and curdlan, having an acid optimum pH activity (ca. 4.0).

Type 1 fimbriae are surface organelles on Escherichia coli, which mediate specific binding to D-mannose-containing structures. These fimbriae are heteropolymers composed of a major building element, the FimA protein, and small amounts of the FimF, FimG and FimH proteins. The FimH protein is uniquely responsible for the D-mannose receptor binding. In this work data are presented which indicate that the major subunit of type 1 fimbriae is dispensable for D-mannose-specific binding. A recombinant strain was studied which harboured an insertional deletion in the fimA gene, and was thereby unable to produce type 1 fimbriae; however, it was still able to express a D-mannose-binding phenotype. However, the deletion resulted in a 25-fold reduction of the adhesive potential, as measured by binding to D-mannose-coated Sepharose beads. Serological and specific receptor binding evidence is presented that suggests that the FimH adhesion is capable of being exposed on the bacterial surface without being an integral part of the fimbriae.

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