title: Role of a geminivirus AV2 protein putative protein kinase C motif on subcellular localization and pathogenicity.
abstract: Virus-derived genes or genome fragments are increasingly being used to generate transgenic plants with resistance to plant viruses. There is need to rapidly investigate these genes in plants using transient expression prior to using them as transgenes since they may be pathogenic to plants. In this study, we investigated the AV2 protein encoded by East African cassava mosaic Cameroon virus, a virus associated with a cassava disease epidemic in western Africa. For subcellular localization, AV2 was fused to the yellow fluorescent protein (YFP) and expressed in Nicotiana benthamiana. Confocal analyses showed that AV2-YFP localizes mainly in the cytoplasm. Because it overlaps with the coat protein gene and therefore could be used to generate transgenic plants for resistance to geminiviruses, we investigated its pathogenesis in N. benthamiana by using the Potato virus X (PVX) vector. The chimeric virus PVX-AV2 induced a mild mottling in infected plants and was shown to suppress virus-induced gene silencing (VIGS). Using point mutations, we show here that AV2 pathogenicity is dependent on a conserved putative protein kinase C (PKC) phosphorylation motif. Because of its pathogenicity and ability to suppress RNA silencing, AV2 transgenic plants will less likely provide a control to geminiviruses, indeed it may weaken the resistance of the plant. We therefore suggest the use of the AV2 putative PKC mutants to generate transgenic plants.
authors.affiliation: Department of Biological Sciences, Delaware State University, 1200 North DuPont Highway, Dover, DE 19901, United States.
authors.forename: R V
authors.initials: RV
authors.lastname: Chowda-Reddy
authors.forename: Fidelis
authors.initials: F
authors.lastname: Achenjang
authors.forename: Christian
authors.initials: C
authors.lastname: Felton
authors.forename: Marie T
authors.initials: MT
authors.lastname: Etarock
authors.forename: Marie-Therese
authors.initials: MT
authors.lastname: Anangfac
authors.forename: Patricia
authors.initials: P
authors.lastname: Nugent
authors.forename: Vincent N
authors.initials: VN
authors.lastname: Fondong
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D053839:Begomovirus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D003593:Cytoplasm / Q000378:metabolism / Q000821:virology; D015870:Gene Expression; D020868:Gene Silencing; D016679:Genome, Viral; D002365:Manihot / Q000821:virology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010935:Plant Diseases / Q000821:virology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D014764:Viral Proteins; D011493:Protein Kinase C