title: Functional comparison of RNA silencing suppressor between the p5 protein of rice grassy stunt virus and the p3 protein of rice stripe virus.
abstract: Rice grassy stunt virus (RGSV) is a member of the genus Tenuivirus, which includes rice stripe virus (RSV), as the type species. A viral suppressor of RNA silencing (VSR) of RGSV has not been identified, whereas the p3 protein of RSV (RSVp3) encoded by the viral-sense (v) strand of RNA3 has been reported to act as a VSR. In this study, we examined the VSR function of the p5 protein of RGSV (RGSVp5), encoded by vRNA5. Expecting it to correspond to the vRNA3 of RSV, we compared the VSR function of RGSVp5 with that of RSVp3. In an Agrobacterium-mediated transient expression assay using a transgenic line of Nicotiana benthamiana that expressed green fluorescent protein and the wild type, RGSVp5 suppressed sense transgene-mediated post-transcriptional gene silencing (S-PTGS), inverted-repeat (IR) transgene-induced PTGS (IR-PTGS), and the systemic spread of GFP silencing, as in the case with RSVp3. By contrast, a gel mobility shift assay revealed that RGSVp5 did not have any distinct binding activity with 21-, 22-, or 24-nucleotide small interfering RNA (siRNA) duplexes, whereas RSVp3 binds to all three sizes of siRNA duplexes. Furthermore, the transiently expressed p5 protein fused with GFP was dispersed mainly in the cytoplasm, whereas the GFP-fused p3 protein of RSV was localized both in the nucleus and in the cytoplasm. Our results suggest that RGSVp5 functions as a VSR but that the suppression mechanism of RNA silencing and the subcellular localization of RGSVp5 differ from those of the analogous VSR, RSVp3, even in the same genus.
authors.affiliation: National Agricultural Research Center, Kannondai, Tsukuba, Ibaraki 305-8666, Japan; Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Netsu
authors.affiliation: National Agricultural Research Center, Kannondai, Tsukuba, Ibaraki 305-8666, Japan; Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hiraguri
authors.affiliation: National Agricultural Research Center, Kannondai, Tsukuba, Ibaraki 305-8666, Japan; National Institute of Agrobiological Sciences, Kannondai, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Tamaki
authors.initials: T
authors.lastname: Uehara-Ichiki
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Laboratory of Plant Pathology, Tokyo University of Agriculture and Technology (TUAT), 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: National Agricultural Research Center, Kannondai, Tsukuba, Ibaraki 305-8666, Japan; Agro-Environment Research Division, NARO Kyushu Okinawa Agricultural Research Center, Koshi, Kumamoto 861-1192, Japan. Electronic address: tsasaya@affrc.go.jp.
authors.forename: Takahide
authors.initials: T
authors.lastname: Sasaya
mesh_terms: D060054:Agrobacterium / Q000235:genetics; D054884:Host-Pathogen Interactions; D030821:Plants, Genetically Modified; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D029364:Tenuivirus / Q000276:immunology* / Q000502:physiology*; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D014764:Viral Proteins
keywords: RNA silencing; Rice grassy stunt virus; Rice stripe virus; VSR; p3 protein; p5 protein