Genomic organization of RNA2 of Tomato ringspot virus: processing at a third cleavage site in the N-terminal region of the polyprotein in vitro.
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.
Carrier
Karma
K
Department of Botany, The University of British Columbia, Vancouver, British Columbia, CanadaV6T 1Z41.
Xiang
Yu
Y
Pacific Agri-Food Research Centre, Summerland, British Columbia, CanadaV0H 1Z02.
Sanfaçon
Hélène
H
Pacific Agri-Food Research Centre, Summerland, British Columbia, CanadaV0H 1Z02.
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
D012367:RNA, Viral; D014764:Viral Proteins; D010450:Endopeptidases