title: Genomic organization of RNA2 of Tomato ringspot virus: processing at a third cleavage site in the N-terminal region of the polyprotein in vitro.
abstract: The proteinase of Tomato ringspot virus (genus Nepovirus) is responsible for proteolytic cleavage of the RNA2-encoded polyprotein (P2) at two cleavage sites, allowing definition of the domains for the movement protein (MP) and coat protein. In this study, we have characterized a third cleavage site in the N-terminal region of P2 using an in vitro processing assay and partial cDNA clones. Results from site-directed mutagenesis of putative cleavage sites suggest that cleavage occurs at dipeptide Q(301)/G. Cleavage at this site is predicted to result in the release of two proteins from the N-terminal region of P2: a 34 kDa protein located at the N terminus of P2 (assuming translation initiation at the first AUG codon) and a 71 kDa protein located immediately upstream of the MP domain. In contrast, only one protein domain is present in the equivalent region of the P2 polyprotein of other characterized nepoviruses.
authors: Department of Botany, The University of British Columbia, Vancouver, British Columbia, CanadaV6T 1Z41.
authors: Karma
authors: K
authors: Carrier
authors: Pacific Agri-Food Research Centre, Summerland, British Columbia, CanadaV0H 1Z02.
authors: Yu
authors: Y
authors: Xiang
authors: Pacific Agri-Food Research Centre, Summerland, British Columbia, CanadaV0H 1Z02.
authors: Hélène
authors: H
authors: Sanfaçon
mesh_terms: D001665:Binding Sites; D010450:Endopeptidases / Q000235:genetics; D018551:Solanum lycopersicum / Q000821:virology*; D016297:Mutagenesis, Site-Directed; D017860:Nepovirus / Q000201:enzymology / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D012367:RNA, Viral / Q000235:genetics; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; D010450:Endopeptidases