title: The R-rich motif of Beet black scorch virus P7a movement protein is important for the nuclear localization, nucleolar targeting and viral infectivity.
abstract: Beet black scorch virus (BBSV) encodes three movement proteins (P7a, P7b and P5') that facilitate its cell-to-cell movement. An arginine-rich motif of P7a N-terminus was found to determine nuclear and nucleolar localization. Amino acids substitution or deletion of the R-rich motif interfered with P7a nuclear and nucleolar localization. Bimolecular fluorescence complementation (BiFC) assays revealed that P7a protein interacted with Nicotiana benthamiana nuclear import factor importin α, suggesting that P7a is translocated into the nucleus by the classical importin α/β-dependent pathway. Moreover, P7a also interacted with the nucleolar protein fibrillarin. Mutations in the R-rich motif of P7a diminished P7a interactions with importin α and fibrillarin, influenced viral replication in Nicotiana benthamiana protoplasts and altered the symptom phenotype and viral RNA accumulation in Chenopodium amaranticolor plants. These results demonstrate that the R-rich motif of P7a is correlated with nuclear and nucleolar localization, viral replication and virus infection.
authors.affiliation: State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
authors.forename: Yanjing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.forename: Lindan
authors.initials: L
authors.lastname: Shi
authors.forename: Huiyan
authors.initials: H
authors.lastname: Fan
authors.forename: Chenggui
authors.initials: C
authors.lastname: Han
authors.forename: Dawei
authors.initials: D
authors.lastname: Li
authors.forename: Jialin
authors.initials: J
authors.lastname: Yu
mesh_terms: D019943:Amino Acid Substitution; D027462:Chenopodium / Q000821:virology; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D028884:Karyopherins / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D019913:Nuclear Localization Signals; D010935:Plant Diseases / Q000821:virology; D053830:Plant Viral Movement Proteins / Q000235:genetics / Q000378:metabolism*; D025941:Protein Interaction Mapping; D014026:Nicotiana / Q000821:virology; D019183:Tombusviridae / Q000235:genetics / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D028884:Karyopherins; D019913:Nuclear Localization Signals; D053830:Plant Viral Movement Proteins; D037521:Virulence Factors; C047458:fibrillarin