title: A second protease of foot-and-mouth disease virus.
abstract: Foot-and-mouth disease virus (FMDV) genes are expressed as a polyprotein which is rapidly processed into the four primary cleavage products L, P1, P2, and P3. In secondary cleavage reactions, these are further processed into the mature proteins. The FMDV L protein is located at the N terminus of the polyprotein and is the first gene product released from the nascent polyprotein. For analysis of its biological function, the L gene was mutated by site-directed mutagenesis of cloned cDNA. In vitro translation of in vitro transcripts of these DNAs and expression studies in Escherichia coli showed that the L mutants affect the processing of the viral polyprotein. The mutants isolated were partially or totally defective in processing the polyprotein at the L/P1 junction. These mutants could, however, be processed in the presence of the wild-type L protein. Furthermore, an antiserum directed against the L protein inhibited processing at the L/P1 cleavage site, so that the release of the L protein from the polyprotein was blocked. These data reveal that the L gene product represents a viral protease which catalyzes its own release from the nascent polyprotein.
mesh_terms: D000818:Animals; D005537:Aphthovirus / Q000201:enzymology*; D005814:Genes, Viral; D007106:Immune Sera / Q000276:immunology; D009154:Mutation; D010447:Peptide Hydrolases / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D010957:Plasmids; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000378:metabolism; D014760:Viral Fusion Proteins; D014764:Viral Proteins / Q000032:analysis*
chemical_list: D007106:Immune Sera; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D014764:Viral Proteins; D010447:Peptide Hydrolases