title: Identification of the cleavage sites of the RNA2-encoded polyproteins for two members of the genus Torradovirus by N-terminal sequencing of the virion capsid proteins.
abstract: Torradoviruses, family Secoviridae, are emergent bipartite RNA plant viruses. RNA1 is ca. 7kb and has one open reading frame (ORF) encoding for the protease, helicase and RNA-dependent RNA polymerase (RdRp). RNA2 is ca. 5kb and has two ORFs. RNA2-ORF1 encodes for a putative protein with unknown function(s). RNA2-ORF2 encodes for a putative movement protein and three capsid proteins. Little is known about the replication and polyprotein processing strategies of torradoviruses. Here, the cleavage sites in the RNA2-ORF2-encoded polyproteins of two torradoviruses, Tomato marchitez virus isolate M (ToMarV-M) and tomato chocolate spot virus, were determined by N-terminal sequencing, revealing that the amino acid (aa) at the -1 position of the cleavage sites is a glutamine. Multiple aa sequence comparison confirmed that this glutamine is conserved among other torradoviruses. Finally, site-directed mutagenesis of conserved aas in the ToMarV-M RdRp and protease prevented substantial accumulation of viral coat proteins or RNAs.
authors: Department of Plant Pathology, University of California, Davis, CA, 95616, USA.
authors: I
authors: I
authors: Ferriol
authors: CAPES Foundation, Ministry of Education of Brazil, Brasília-DF, Brazil.
authors: D M
authors: DM
authors: Silva Junior
authors: Department of Plant Pathology, University of California, Davis, CA, 95616, USA.
authors: J C
authors: JC
authors: Nigg
authors: Colegio de Postgraduados-Campus Montecillo, 56230 Texcoco, Mexico.
authors: E J
authors: EJ
authors: Zamora-Macorra
authors: Department of Plant Pathology, University of California, Davis, CA, 95616, USA. Electronic address: bwfalk@ucdavis.edu.
authors: B W
authors: BW
authors: Falk
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D016366:Open Reading Frames; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010849:Picornaviridae / Q000502:physiology*; D020815:Polyproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D059748:Proteolysis; D012367:RNA, Viral
chemical_list: D036022:Capsid Proteins; D020815:Polyproteins; D012367:RNA, Viral; D010447:Peptide Hydrolases
keywords: Cleavage sites; N-terminal sequencing; Polyprotein; Torradovirus