Rotavirus Architecture at Subnanometer Resolution
Rotavirus Architecture at Subnanometer Resolution
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DOI：
10.1128/jvi.01855-08
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发表时间：
2009-02-15
影响因子：
5.4
通讯作者：
Prasad, B. V. Venkataram
中科院分区：
文献类型：
--
作者：
Li, Zongli;Baker, Matthew L.;Prasad, B. V. Venkataram
轮状病毒是呼肠孤病毒科的一种无角病毒，是严重婴儿腹泻的病原体。双链RNA基因组编码构成三层颗粒的六种结构蛋白。 X 射线晶体学阐明了其中一种衣壳蛋白 VP6 和 VP4（刺突蛋白）的两个结构域的结构。作为这项工作的补充，电子冷冻显微镜（cryoEM）为几种生化状态下的三层衣壳提供了相对低分辨率的结构。然而，完整的、高分辨率的轮状病毒结构模型仍未解决。将新的结构分析技术与轮状病毒的亚纳米分辨率冷冻电镜结构相结合，我们现在为主要衣壳蛋白及其在三层颗粒内的相互作用提供了更详细的结构模型。通过一系列亚基间相互作用，刺突蛋白 (VP4) 在衣壳表面上方呈现二聚体外观，同时形成锚定在 VP7 和 VP6 衣壳层之间三种水通道之一内的三聚体碱基。虽然三聚体碱基表明一个刺突中存在三个 VP4 分子，但在衣壳表面上方仅观察到第三个分子的痕迹。除了与 VP4 的相互作用之外，VP6 和 VP7 亚基之间的相互作用也可以很容易地识别。在由 VP2 组成的最里面的 T = 1 层中，二级结构元素的可视化使我们能够识别 VP2 的多肽折叠，并检查该层与 T = 13 VP6 层之间相互作用的复杂网络。这种集成的结构方法为轮状病毒的完整、感染性结构提供了相对高分辨率的结构模型，并揭示了在如此大的大分子组装体中维持相互作用所需的细微差别。
Rotavirus, a nonturreted member of the Reoviridae, is the causative agent of severe infantile diarrhea. The double-stranded RNA genome encodes six structural proteins that make up the triple-layer particle. X-ray crystallography has elucidated the structure of one of these capsid proteins, VP6, and two domains from VP4, the spike protein. Complementing this work, electron cryomicroscopy (cryoEM) has provided relatively low-resolution structures for the triple-layer capsid in several biochemical states. However, a complete, high-resolution structural model of rotavirus remains unresolved. Combining new structural analysis techniques with the subnanometer-resolution cryoEM structure of rotavirus, we now provide a more detailed structural model for the major capsid proteins and their interactions within the triple-layer particle. Through a series of intersubunit interactions, the spike protein (VP4) adopts a dimeric appearance above the capsid surface, while forming a trimeric base anchored inside one of the three types of aqueous channels between VP7 and VP6 capsid layers. While the trimeric base suggests the presence of three VP4 molecules in one spike, only hints of the third molecule are observed above the capsid surface. Beyond their interactions with VP4, the interactions between VP6 and VP7 subunits could also be readily identified. In the innermost T = 1 layer composed of VP2, visualization of the secondary structure elements allowed us to identify the polypeptide fold for VP2 and examine the complex network of interactions between this layer and the T = 13 VP6 layer. This integrated structural approach has resulted in a relatively high-resolution structural model for the complete, infectious structure of rotavirus, as well as revealing the subtle nuances required for maintaining interactions in such a large macromolecular assembly.