Institute for Protein Research, Osaka University, Suita, Osaka 565-0871 Japan; Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology, Higashi-Hiroshima, Hiroshima 739-0046 Japan.
Institute for Protein Research, Osaka University, Suita, Osaka 565-0871 Japan; National Institute for Physiological Sciences, Okazaki, Aichi 444-8787 Japan.
Structure. 2019 Mar 5;27(3):439-448.e3. doi: 10.1016/j.str.2018.10.029. Epub 2018 Dec 20.
Nearly all viruses of the Reoviridae family possess a multi-layered capsid consisting of an inner layer with icosahedral T = 1 symmetry and a second-outer layer (composed of 260 copies of a trimeric protein) exhibiting icosahedral T = 13 symmetry. Here we describe the construction and structural evaluation of an assembly intermediate of the Rice dwarf virus of the family Reoviridae stalled at the second capsid layer via targeted disruption of the trimer-trimer interaction interface in the second-layer capsid protein. Structural determination was performed by conventional and Zernike/Volta phase-contrast cryoelectron microscopy. The assembly defect second-layer capsid trimers bound exclusively to the outer surface of the innermost capsid layer at the icosahedral 3-fold axis. Furthermore, the second-layer assembly could not proceed without specific inter-trimer interactions. Our results suggest that the correct assembly pathway for second-layer capsid formation is highly controlled at the inter-layer and inter-trimer interactions.
几乎所有呼肠孤病毒科的病毒都具有多层衣壳，由具有二十面体 T=1 对称性的内层和第二层（由 260 个三聚体蛋白组成）组成，具有二十面体 T=13 对称性。在这里，我们描述了家族呼肠孤病毒的水稻矮缩病毒的一个组装中间物的构建和结构评估，该中间物通过靶向破坏第二层衣壳蛋白中三聚体-三聚体相互作用界面而停滞在第二层衣壳。结构测定通过常规和泽尼克/沃尔塔相衬 cryoEM 进行。组装缺陷的第二层衣壳三聚体仅与最内层衣壳层的二十面体 3 重轴的外表面结合。此外，如果没有特定的三聚体间相互作用，第二层的组装就无法进行。我们的结果表明，第二层衣壳形成的正确组装途径在层间和三聚体间相互作用中受到高度控制。
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