title: Nucleo-cytoplasmic shuttling of VPg encoded by Wheat yellow mosaic virus requires association with the coat protein.
abstract: VPg (virus protein, genome-linked) is a multifunctional protein that plays important roles in viral multiplication in the cytoplasm. However, a number of VPgs encoded by plant viruses target the nucleus and this appears to be biologically significant. These VPgs may therefore be translocated between nuclear and cytoplasmic compartments during virus infection, but such nucleo-cytoplasmic transport has not been demonstrated. We report that VPg encoded by Wheat yellow mosaic virus (WYMV, genus Bymovirus, family Potyviridae) accumulated in both the nucleus and cytoplasm of infected cells, but localized exclusively in the nucleus when expressed alone in plants. Computational analyses predicted the presence of a nuclear localization signal (NLS) and a nuclear export signal (NES) in WYMV VPg. Mutational analyses showed that both the N-terminal and the NLS domains of VPg contribute to the efficiency of nuclear targeting. In vitro and in planta assays indicated that VPg interacts with WYMV coat protein (CP) and proteinase 1 (P1) proteins. Observation of VPg fused to a fluorescent protein and subcellular fractionation experiments showed that VPg was translocated to the cytoplasm when co-expressed with CP, but not with P1. Mutations in the NES domain or treatment with leptomycin B prevented VPg translocation to the cytoplasm when co-expressed with CP. Our results suggest that association with CP facilitates the nuclear export of VPg during WYMV infection.
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China.
authors.forename: Liying
authors.initials: L
authors.lastname: Sun
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Bian
authors.initials: B
authors.lastname: Jing
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China.
authors.forename: Ida Bagus
authors.initials: IB
authors.lastname: Andika
authors.affiliation: Key Laboratory of Ministry of Education for Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing 100871, PR China.
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Hu
authors.affiliation: College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, Henan Province, PR China.
authors.forename: Bingjian
authors.initials: B
authors.lastname: Sun
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Rong
authors.initials: R
authors.lastname: Xiang
authors.affiliation: Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki 710-0046, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Kondo
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D008969:Molecular Sequence Data; D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals / Q000378:metabolism; D019176:Potyviridae / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014908:Triticum / Q000821:virology*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D036022:Capsid Proteins; D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals; D012261:Ribonucleoproteins; D017361:Viral Nonstructural Proteins