Cloning of a cuticle-degrading protease from the entomopathogenic fungus,Beauveria bassiana

A Beauveria bassiana extracellular subtilisin-like serine endoprotease is a potential virulence factor by virtue of its activity against insect cuticles. A cDNA clone of the protease was isolated from mycelia of B. bassiana grown on cuticle/chitin cultures. The amino acid sequence of this gene was compared to that of Metarhizium anisopliae Pr1, the only pathogenicity determinant so far described from an entomopathogenic fungus, and proteinase K, isolated from Tritirachium album, a saprophytic fungus. The cDNA sequence revealed that B. bassiana Pr1 is synthesized as a large precursor (M(r) 37,460) containing a signal peptide, a propeptide and the mature protein predicted to have an M(r) of 26,832.