PROTEIN-SYNTHESIS IN METARHIZIUM-ANISOPLIAE GROWING ON HOST CUTICLE

In vitro protein synthesis using poly(A(+))RNA and a two-step gel syst em for proteins were used in this study on the entomopathogenic fungus Metarhizium anisopliae to provide an estimate of the magnitude of dif ferential protein synthesis and secretion that may be involved in adap ting to growth on insect cuticle. Shortly after being transferred to a media containing cockroach cuticle, mRNAs for certain proteins are re pressed while a broad array of mRNAs for other proteins is induced. Co ncurrent with this, a least 42 proteins were secreted into the media i n a process which was sensitive to actinomycin D. The majority of thes e proteins were acidic (pl range 4.2-5.6) and co-migrated with Con-A/p eroxidase stained bands indicating that they might be glycoconjugates. Microsequencing of those polypeptides accumulated in large amounts re vealed two NH2-terminal amino acid sequences from acidic proteins that were highly homologous to those of animal trypsins. The trypsin natur e of the two proteins was confirmed using a combination of gelatin-SDS -polyacrylamide gel electrophoresis and enzyme overlay membranes. The NH2-terminal sequence of the major basic protein identified it as a kn own subtilisin-like proteinase (Pr1). A second basic sequence was iden tified asa carboxypeptidase. No other homologies were found.