Protein Synthesis in Metarhizium Anisopliae Grown on Host Cuticle

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Mycological Research





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In vitro protein synthesis using poly(A+)RNA and a two-step gel system for proteins were used in this study on the entomopathogenic fungus Metarhizium anisopliae to provide an estimate of the magnitude of differential protein synthesis and secretion that may be involved in adapting to growth on insect cuticle. Shortly after being transferred to a media containing cockroach cuticle, mRNAs for certain proteins are repressed while a broad array of mRNAs for other proteins is induced. Concurrent with this, a least 42 proteins were secreted into the media in a process which was sensitive to actinomycin D. The majority of these proteins were acidic (pI range 4·2–5·6) and co-migrated with Con-A/peroxidase stained bands indicating that they might be glycoconjugates. Microsequencing of those polypeptides accumulated in large amounts revealed two NH2-terminal amino acid sequences from acidic proteins that were highly homologous to those of animal trypsins. The trypsin nature 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 know subtilisin-like proteinase (Pr1). A second basic sequence was identified as a carboxypeptidase. No other homologies were found.

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