title: A second proteinase encoded by a plant potyvirus genome.
abstract: The RNA genome of tobacco etch virus (TEV) encodes a large polyprotein precursor that is processed to mature proteins by virus-specific proteinases. Cleavage sites located within the carboxyl-terminal two-thirds of the polyprotein are processed by a TEV-encoded 49 kd proteinase, while the enzyme(s) responsible for cleaving the remaining sites has not been found. In this study, a second TEV-encoded proteinase has been identified based on cell-free expression of defined RNA transcripts. The boundaries of this proteinase have been delineated by deletion analysis and site-directed mutagenesis. The proteolytically active domain has been localized to the carboxyl-terminal half of the 56 kd aphid-transmission helper component. A cleavage site that is recognized by this proteinase has been identified in the polyprotein adjacent to the carboxyl-terminus of the enzyme, and the proteinase appears to cleave by an autocatalytic mechanism. Proteolysis in vitro occurs between a Gly-Gly dipeptide as determined by radiochemical sequencing at the amino-terminus of the proteolytic product.
authors.affiliation: Department of Biology, Texas A&M University, College Station 77843.
authors.forename: J C
authors.initials: JC
authors.lastname: Carrington
authors.forename: S M
authors.initials: SM
authors.lastname: Cary
authors.forename: T D
authors.initials: TD
authors.lastname: Parks
authors.forename: W G
authors.initials: WG
authors.lastname: Dougherty
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D005814:Genes, Viral; D008969:Molecular Sequence Data; D009154:Mutation; D010942:Plant Viruses / Q000235:genetics* / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational
chemical_list: D011498:Protein Precursors; D010450:Endopeptidases