title: Detection of the potyviral genome-linked protein VPg in virions and its phosphorylation by host kinases.
abstract: The multifunctional genome-linked protein (VPg) of Potato virus A (PVA; genus Potyvirus) was found to be phosphorylated as a part of the virus particle by a cellular kinase activity from tobacco. Immunoprecipitation, immunolabeling, and immunoelectron microscopy experiments showed that VPg is exposed at one end of the virion and it is accessible to protein-protein interactions. Substitution Ser185Leu at the C-proximal part of VPg reduces accumulation of PVA in inoculated leaves of the wild potato species Solanum commersonii and delays systemic infection, which is not observed in tobacco plants. Our data show that kinases of S. commersonii differentially recognize the VPg containing Ser or Leu at position 185, whereas both forms of VPg are similarly recognized by tobacco kinases. Taken together, our data imply that the virion-bound VPg may interact with host proteins and that phosphorylation of VPg may play a role in the VPg-mediated functions during the infection cycle of potyviruses.
authors.affiliation: Institute of Biotechnology, Viikki Biocenter, FIN-00014 University of Helsinki, Finland.
authors.forename: Pietri
authors.initials: P
authors.lastname: Puustinen
authors.forename: Minna-Liisa
authors.initials: ML
authors.lastname: Rajamäki
authors.forename: Konstantin I
authors.initials: KI
authors.lastname: Ivanov
authors.forename: Jari P T
authors.initials: JP
authors.lastname: Valkonen
authors.forename: Kristiina
authors.initials: K
authors.lastname: Mäkinen
mesh_terms: D016679:Genome, Viral; D010766:Phosphorylation; D010940:Plant Proteins / Q000502:physiology*; D017800:Potyvirus / Q000737:chemistry*; D011233:Precipitin Tests; D011494:Protein Kinases / Q000502:physiology*; D011198:Solanum tuberosum / Q000201:enzymology / Q000821:virology*; D013379:Substrate Specificity; D014758:Viral Core Proteins / Q000032:analysis* / Q000378:metabolism; D014771:Virion / Q000737:chemistry*
chemical_list: D010940:Plant Proteins; D014758:Viral Core Proteins; D011494:Protein Kinases