Reovirus polymerase λ3 localized by cryo-electron microscopy of virions at a resolution of 7.6 Å
Reovirus polymerase λ3 localized by cryo-electron microscopy of virions at a resolution of 7.6 Å
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DOI：
10.1038/nsb1009
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发表时间：
2003-12-01
期刊：
影响因子：
--
通讯作者：
Baker, TS
中科院分区：
文献类型：
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作者：
Zhang, X;Walker, SB;Baker, TS
呼肠孤病毒是一种二十面体双链（ds）RNA病毒，其使用包装在病毒核心内的病毒聚合酶来转录其十个不同的正链RNA。为了定位这些聚合酶，通过冷冻电子显微镜（cryo-EM）和三维（3D）图像重建将reovirion的结构细化到7.6埃的分辨率。然后将呼肠孤病毒蛋白质的X射线晶体模型，包括聚合酶β 3，拟合到密度图中。发现每个拷贝的p53都锚定在二十面体核壳的内表面，与三个壳蛋白p53 1分子主要接触，并重叠，但不以五重轴为中心。这种重叠解释了为什么每个顶点只有一个副本绑定到Renda 3。此外，Renda 3的转录物出口通道朝向穿过Renda 1壳的小通道，这表明新生RNA如何进入由蛋白Renda 2形成的五聚体加帽酶复合物的大外部空腔。
Reovirus is an icosahedral, double-stranded (ds) RNA virus that uses viral polymerases packaged within the viral core to transcribe its ten distinct plus-strand RNAs. To localize these polymerases, the structure of the reovirion was refined to a resolution of 7.6 Angstrom by cryo-electron microscopy (cryo-EM) and three-dimensional (3D) image reconstruction. X-ray crystal models of reovirus proteins, including polymerase lambda3, were then fitted into the density map. Each copy of lambda3 was found anchored to the inner surface of the icosahedral core shell, making major contacts with three molecules of shell protein lambda1 and overlapping, but not centering on, a five-fold axis. The overlap explains why only one copy of lambda3 is bound per vertex. lambda3 is furthermore oriented with its transcript exit channel facing a small channel through the lambda1 shell, suggesting how the nascent RNA is passed into the large external cavity of the pentameric capping enzyme complex formed by protein lambda2.