title: Viroplasm matrix protein Pns9 from rice gall dwarf virus forms an octameric cylindrical structure.
abstract: The non-structural Pns9 protein of rice gall dwarf virus (RGDV) accumulates in viroplasm inclusions, which are structures that appear to play an important role in viral morphogenesis and are commonly found in host cells infected by viruses in the family Reoviridae. Immunofluorescence and immunoelectron microscopy of RGDV-infected vector cells in monolayers, using antibodies against Pns9 of RGDV and expression of Pns9 in Spodoptera frugiperda cells, demonstrated that Pns9 is the minimal viral factor necessary for formation of viroplasm inclusion during infection by RGDV. When Pns9 in solution was observed under a conventional electron microscope, it appeared as ring-like aggregates of approximately 100 Å in diameter. Cryo-electron microscopic analysis of these aggregates revealed cylinders of octameric Pns9, whose dimensions were similar to those observed under the conventional electron microscope. Octamerization of Pns9 in solution was confirmed by the results of size-exclusion chromatography. Among proteins of viruses that belong to the family Reoviridae whose three-dimensional structures are available, a matrix protein of the viroplasm of rotavirus, NSP2, forms similar octamers, an observation that suggests similar roles for Pns9 and NSP2 in morphogenesis in animal-infecting and in plant-infecting reoviruses.
authors: National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan.
authors: Fusamichi
authors: F
authors: Akita
authors: Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.|Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Naoyuki
authors: N
authors: Miyazaki
authors: National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan.
authors: Hiroyuki
authors: H
authors: Hibino
authors: National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan.
authors: Takumi
authors: T
authors: Shimizu
authors: Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Akifumi
authors: A
authors: Higashiura
authors: National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan.
authors: Tamaki
authors: T
authors: Uehara-Ichiki
authors: National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan.
authors: Takahide
authors: T
authors: Sasaya
authors: Department of Life Science, University of Hyogo, 3-2-1 Koto, Kamighori, Akoh, Hyogo 678-1297, Japan.|Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Tomitake
authors: T
authors: Tsukihara
authors: Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Atsushi
authors: A
authors: Nakagawa
authors: Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.|Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Kenji
authors: K
authors: Iwasaki
authors: National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan.
authors: Toshihiro
authors: T
authors: Omura