Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.
J Virol. 2010 May;84(9):4426-41. doi: 10.1128/JVI.02393-09. Epub 2010 Feb 24.
Poliovirus infection requires that the particle undergo a series of conformational transitions that lead to cell entry and genome release. In an effort to understand the conformational changes associated with the release of the RNA genome, we have used cryo-electron microscopy to characterize the structure of the 80S "empty" particles of poliovirus that are thought to represent the final product of the cell entry pathway. Using two-dimensional classification methods, we show that preparations of 80S particles contain at least two structures, which might represent snapshots from a continuous series of conformers. Using three-dimensional reconstruction methods, we have solved the structure of two distinct forms at subnanometric resolution, and we have built and refined pseudoatomic models into the reconstructions. The reconstructions and the derived models demonstrate that the two structural forms are both slightly expanded, resulting in partial disruption of interprotomer interfaces near their particle 2-fold axes, which may represent the site where RNA is released. The models demonstrate that each of the two 80S structures has undergone a unique set of movements of the capsid proteins, associated with rearrangement of flexible loops and amino-terminal extensions that participate in contacts between protomers, between pentamers, and with the viral RNA.
脊髓灰质炎病毒感染需要病毒颗粒经历一系列构象转变，从而导致细胞进入和基因组释放。为了了解与 RNA 基因组释放相关的构象变化，我们使用冷冻电子显微镜来描述被认为代表细胞进入途径的最终产物的脊髓灰质炎病毒 80S“空”颗粒的结构。使用二维分类方法，我们表明 80S 颗粒的制剂至少包含两种结构，它们可能代表连续构象的快照。使用三维重建方法，我们以亚纳米分辨率解决了两种不同形式的结构，并将伪原子模型构建和细化到重建中。重建和推导的模型表明，这两种结构形式都略有膨胀，导致其 2 倍轴附近的蛋白间界面部分破坏，这可能代表 RNA 释放的部位。模型表明，这两种 80S 结构中的每一种都经历了一组独特的衣壳蛋白运动，与参与五聚体之间和与病毒 RNA 之间的构象变化相关联。
