ジャーナル: PLoS One / 年: 2016 タイトル: Structure of a Bacterial Virus DNA-Injection Protein Complex Reveals a Decameric Assembly with a Constricted Molecular Channel. 著者: Haiyan Zhao / Jeffrey A Speir / Tsutomu Matsui / Zihan Lin / Lingfei Liang / Anna Y Lynn / Brittany Varnado / Thomas M Weiss / Liang Tang / 要旨: The multi-layered cell envelope structure of Gram-negative bacteria represents significant physical and chemical barriers for short-tailed phages to inject phage DNA into the host cytoplasm. Here we ...The multi-layered cell envelope structure of Gram-negative bacteria represents significant physical and chemical barriers for short-tailed phages to inject phage DNA into the host cytoplasm. Here we show that a DNA-injection protein of bacteriophage Sf6, gp12, forms a 465-kDa, decameric assembly in vitro. The electron microscopic structure of the gp12 assembly shows a ~150-Å, mushroom-like architecture consisting of a crown domain and a tube-like domain, which embraces a 25-Å-wide channel that could precisely accommodate dsDNA. The constricted channel suggests that gp12 mediates rapid, uni-directional injection of phage DNA into host cells by providing a molecular conduit for DNA translocation. The assembly exhibits a 10-fold symmetry, which may be a common feature among DNA-injection proteins of P22-like phages and may suggest a symmetry mismatch with respect to the 6-fold symmetric phage tail. The gp12 monomer is highly flexible in solution, supporting a mechanism for translocation of the protein through the conduit of the phage tail toward the host cell envelope, where it assembles into a DNA-injection device.
A total of 86783 particles were boxed with a dimension of 128x128 pixels and a pixel size of 2.73 A using the program DoGPicker in the Appion pipeline. Image analysis and 3D reconstruction were performed using RELION. No symmetry was applied during 2D classification. After 2D classification, 54104 particles associated with high-quality class averages were included for the subsequent 3D reconstruction. In the 3D reconstruction, 10-fold rotational symmetry was applied.
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アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 11.0 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: RELION / 使用した粒子像数: 54104