title: Downregulation of the NbNACa1 gene encoding a movement-protein-interacting protein reduces cell-to-cell movement of Brome mosaic virus in Nicotiana benthamiana.
abstract: The 3a movement protein (MP) plays a central role in the movement of the RNA plant virus, Brome mosaic virus (BMV). To identify host factor genes involved in viral movement, a cDNA library of Nicotiana benthamiana, a systemic host for BMV, was screened with far-Western blotting using a recombinant BMV MP as probe. One positive clone encoded a protein with sequence similarity to the alpha chain of nascent-polypeptide-associated complex from various organisms, which is proposed to contribute to the fidelity of translocation of newly synthesized proteins. The orthologous gene from N. benthamiana was designated NbNACa1. The binding of NbNACa1 to BMV MP was confirmed in vivo with an agroinfiltration-immunoprecipitation assay. To investigate the involvement of NbNACa1 in BMV multiplication, NbNACa1-silenced (GSNAC) transgenic N. benthamiana plants were produced. Downregulation of NbNACa1 expression reduced virus accumulation in inoculated leaves but not in protoplasts. A microprojectile bombardment assay to monitor BMV-MP-assisted viral movement demonstrated reduced virus spread in GSNAC plants. The localization to the cell wall of BMV MP fused to green fluorescent protein was delayed in GSNAC plants. From these results, we propose that NbNACa1 is involved in BMV cell-to-cell movement through the regulation of BMV MP localization to the plasmodesmata.
authors.affiliation: Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kaido
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yoshika
authors.initials: Y
authors.lastname: Takeda
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Sugiyama
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takeda
authors.forename: Masashi
authors.initials: M
authors.lastname: Mori
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tamai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Meshi
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Okuno
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Mise
mesh_terms: D001692:Biological Transport; D026481:Blotting, Far-Western; D017795:Bromovirus / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D020868:Gene Silencing; D017343:Genes, Plant; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000821:virology; D010940:Plant Proteins / Q000235:genetics*; D053830:Plant Viral Movement Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D011523:Protoplasts / Q000821:virology; D014026:Nicotiana / Q000166:cytology / Q000235:genetics* / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000502:physiology; D014779:Virus Replication
chemical_list: D010940:Plant Proteins; D053830:Plant Viral Movement Proteins