title: The Barley stripe mosaic virus γb protein promotes chloroplast-targeted replication by enhancing unwinding of RNA duplexes.
abstract: RNA viruses encode various RNA binding proteins that function in many steps of viral infection cycles. These proteins function as RNA helicases, methyltransferases, RNA-dependent RNA polymerases, RNA silencing suppressors, RNA chaperones, movement proteins, and so on. Although many of the proteins bind the viral RNA genome during different stages of infection, our knowledge about the coordination of their functions is limited. In this study, we describe a novel role for the Barley stripe mosaic virus (BSMV) γb as an enhancer of αa RNA helicase activity, and we show that the γb protein is recruited by the αa viral replication protein to chloroplast membrane sites of BSMV replication. Mutagenesis or deletion of γb from BSMV resulted in reduced positive strand (+) RNAα accumulation, but γb mutations abolishing viral suppressor of RNA silencing (VSR) activity did not completely eliminate genomic RNA replication. In addition, cis- or trans-expression of the Tomato bushy stunt virus p19 VSR protein failed to complement the γb replication functions, indicating that the direct involvement of γb in BSMV RNA replication is independent of VSR functions. These data support a model whereby two BSMV-encoded RNA-binding proteins act coordinately to regulate viral genome replication and provide new insights into strategies whereby double-stranded viral RNA unwinding is regulated, as well as formation of viral replication complexes.
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Kun
authors.initials: K
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Meng
authors.initials: M
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Songyu
authors.initials: S
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Xianbing
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Chenggui
authors.initials: C
authors.lastname: Han
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Jialin
authors.initials: J
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China.
authors.forename: Dawei
authors.identifier: http://orcid.org/0000-0003-4133-1263
authors.initials: D
authors.lastname: Li
mesh_terms: D002736:Chloroplasts / Q000378:metabolism / Q000821:virology*; D015870:Gene Expression / Q000502:physiology; D009029:Mosaic Viruses / Q000302:isolation & purification*; D034622:RNA Interference / Q000502:physiology; D012328:RNA Viruses / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology*
chemical_list: D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; D012324:RNA-Dependent RNA Polymerase