REGULATION OF PRODUCTION OF A TRYPSIN-LIKE PROTEASE BY THE INSECT PATHOGENIC FUNGUS METARHIZIUM-ANISOPLIAE

The entomopathogenic fungus Metarhizium anisopliae produces several cu ticle-degrading proteases which may play a role in pathogenesis. The r egulation of one of these, a trypsin-like protease PR2, has been inves tigated using derepressed mycelia. Three insoluble protein sources, in sect cuticle, elastin and collagen, as well as two soluble proteins, B SA and gelatin, induced PR2. The polymeric carbon sources cellulose an d xylan resulted in derepressed basal levels but not induced productio n of PR2. An approximately 15-fold increase in PR2 activity per mg dry weight of mycelium was observed when the fungus was grown in the pres ence of bovine serum albumin (BSA), as compared with conditions of der epression alone. This indicates that PR2 is induced by BSA, and probab ly by other proteins. Basal levels of PR2 were detected after 8 h when mycelium was starved for both carbon and nitrogen but only after 16 h when starved for either nitrogen or carbon. In the presence of a prot ein source, nitrogen strongly repressed PR2 whereas carbon had little effect. There was no effect of sulphur on PR2 production.