Three-dimensional structure of scaffolding-containing phage P22 procapsids by electron cryo-microscopy
Three-dimensional structure of scaffolding-containing phage P22 procapsids by electron cryo-microscopy
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DOI：
10.1006/jmbi.1996.0383
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发表时间：
1996-07-05
影响因子：
5.6
通讯作者：
Chiu, W
中科院分区：
文献类型：
--
作者：
ThumanCommike, PA;Greene, B;Chiu, W
细菌病毒的衣壳是外壳和支架亚基聚合的产物，也是DNA包装的前体。电子冷冻显微镜已用于研究含有野生型和突变型支架蛋白的噬菌体 P22 衣壳的三维结构。支架突变体结构已解析至 19 埃分辨率，并与 22 埃分辨率野生型原衣壳重建一致。两种衣壳重建都包含外部二十面体外壳蛋白壳和内部支架蛋白核心。外核蛋白形成 T = 7 二十面体晶格，五邻体和苍鹭中心具有独特的通道。此外，苍鹭表现出明显的倾斜。倾斜六邻体的计算分离表明存在局部二重轴，该轴将不对称单元中独特构象的数量减少到在此分辨率下的四个。根据上部结构域的形状和通向内部外壳蛋白表面的通道的存在，我们将四个独特的亚基分为三个不同的类别。此外，在外壳蛋白的内表面，两个亚基中存在向支架蛋白核心延伸的指状区域。手指状区域表明内外壳蛋白和支架蛋白之间存在有序的相互作用。然而，没有形成二十面体支架蛋白壳，并且最里面的支架蛋白核心也没有以二十面体对称性包装。 (C) 1996 学术出版社有限公司
The procapsids of bacterial viruses are the products of the polymerization of coat and scaffolding subunits, as well as the precursors in DNA packaging. Electron cryo-microscopy has been used to study the three-dimensional structures of bacteriophage P22 procapsids containing wild-type and mutant scaffolding proteins. The scaffolding mutant structure has been resolved to 19 Angstrom resolution and agrees with the 22 Angstrom resolution wild-type procapsid reconstruction. Both procapsid reconstructions contain an outer icosahedral coat protein shell and an inner scaffolding protein core. The outer core protein forms a T = 7 icosahedral lattice with distinctive channels present at the centers of the pentons and herons. In addition, the herons display a prominent skew. Computational isolation of the skewed hexon shows the presence of a local 2-fold axis that reduces the number of unique conformations in the asymmetric unit to four at this resolution. We have classified the four unique subunits into three distinct classes, based upon the shape of the upper domain and the presence of a channel leading to the inner coat protein surface. In addition, at the inner surface of the coat protein, finger-like regions that extend towards the scaffolding protein core are present in two of the subunits. The finger-like regions suggest the presence of an ordered interaction between the inner coat protein and the scaffolding protein. However, an icosahedral scaffolding protein shell is not formed, and the innermost scaffolding protein core does not pack with icosahedral symmetry. (C) 1996 Academic Press Limited