title: A critical domain of Sweet potato chlorotic fleck virus nucleotide-binding protein (NaBp) for RNA silencing suppression, nuclear localization and viral pathogenesis.
abstract: RNA silencing is an important mechanism of antiviral defence in plants. To counteract this resistance mechanism, many viruses have evolved RNA silencing suppressors. In this study, we analysed five proteins encoded by Sweet potato chlorotic fleck virus (SPCFV) for their abilities to suppress RNA silencing using a green fluorescent protein (GFP)-based transient expression assay in Nicotiana benthamiana line 16c plants. Our results showed that a putative nucleotide-binding protein (NaBp), but not other proteins encoded by the virus, could efficiently suppress local and systemic RNA silencing induced by either sense or double-stranded RNA (dsRNA) molecules. Deletion mutation analysis of NaBp demonstrated that the basic motif (an arginine-rich region) was critical for its RNA silencing suppression activity. Using confocal laser scanning microscopy imaging of transfected protoplasts expressing NaBp fused to GFP, we showed that NaBp accumulated predominantly in the nucleus. Mutational analysis of NaBp demonstrated that the basic motif represented part of the nuclear localization signal. In addition, we demonstrated that the basic motif in NaBp was a pathogenicity determinant in the Potato virus X (PVX) heterogeneous system. Overall, our results demonstrate that the basic motif of SPCFV NaBp plays a critical role in RNA silencing suppression, nuclear localization and viral pathogenesis.
authors.affiliation: Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610064, China.
authors.forename: Xing-Guang
authors.initials: XG
authors.lastname: Deng
authors.forename: Xing-Ji
authors.initials: XJ
authors.lastname: Peng
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.forename: Ying-Juan
authors.initials: YJ
authors.lastname: Chen
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
authors.forename: Shao-Bo
authors.initials: SB
authors.lastname: Qin
authors.forename: De-Hui
authors.initials: DH
authors.lastname: Xi
authors.forename: Hong-Hui
authors.initials: HH
authors.lastname: Lin
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism*; D027723:Ipomoea batatas / Q000821:virology*; D009154:Mutation; D010942:Plant Viruses / Q000378:metabolism* / Q000472:pathogenicity; D034622:RNA Interference; D012328:RNA Viruses / Q000378:metabolism* / Q000472:pathogenicity; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D014764:Viral Proteins
keywords: NaBp; SPCFV; nuclear localization; silencing suppressor; viral pathogenesis