Intermediates in the assembly pathway of the double-stranded RNA virus phi 6
Intermediates in the assembly pathway of the double-stranded RNA virus phi 6
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DOI：
10.1093/emboj/16.14.4477
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发表时间：
1997-07-16
期刊：
影响因子：
11.4
通讯作者：
Fuller, SD
中科院分区：
文献类型：
--
作者：
Butcher, SJ;Dokland, T;Fuller, SD
双链RNA噬菌体phi 6含有由脂质包膜包围的核衣壳。核衣壳具有蛋白质P8的外层和由四种蛋白质P1、P2、P4和P7组成的核心。这四种蛋白质形成了作为RNA包装和聚合酶复合物的多面体结构，这四种蛋白质在大肠杆菌中的同时表达产生了可以进行整个RNA复制循环的原衣壳。利用冷冻电子显微照片的二十面体图像重建来确定病毒粒子分离的核衣壳和核心的三维结构，以及在E.杆菌核衣壳具有T = 13的表面晶格，主要由P8组成。核心是一个圆形结构，塔楼从5重顶点突出，而前壳比核心小，并且更多的是十二面体。核心和原衣壳之间的差异表明，成熟涉及广泛的结构重排产生扩张。这些重排与导致病毒组装的包装和RNA聚合反应协调。phi 6组装中间体的这种结构表征揭示了导致病毒体组装的专性阶段的有序进展，沿着与相应呼肠孤病毒科结构的惊人相似性。
The double-stranded RNA bacteriophage phi 6 contains a nucleocapsid enclosed by a lipid envelope. The nucleocapsid has an outer layer of protein P8 and a core consisting of the four proteins P1, P2, P4 and P7. These four proteins form the polyhedral structure which acts as the RNA packaging and polymerase complex, Simultaneous expression of these four proteins in Escherichia coli gives rise to procapsids that can carry out the entire RNA replication cycle. Icosahedral image reconstruction from cryo electron micrographs was used to determine the three-dimensional structures of the virion-isolated nucleocapsid and core, and of several procapsid-related particles expressed and assembled in E. coli. The nucleocapsid has a T = 13 surface lattice, composed primarily of P8. The core is a rounded structure with turrets projecting from the 5-fold vertices, while the procapsid is smaller than the core and more dodecahedral. The differences between the core and the procapsid suggest that maturation involves extensive structural rearrangements producing expansion. These rearrangements are co-ordinated with the packaging and RNA polymerization reactions that result in virus assembly, This structural characterization of the phi 6 assembly intermediates reveals the ordered progression of obligate stages leading to virion assembly along with striking similarities to the corresponding Reoviridae structures.