Rotavirus VP2 Core Shell Regions Critical for Viral Polymerase Activation
Rotavirus VP2 Core Shell Regions Critical for Viral Polymerase Activation
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DOI：
10.1128/jvi.02360-10
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发表时间：
2011-04-01
影响因子：
5.4
通讯作者：
Patton, John T.
中科院分区：
文献类型：
--
作者：
McDonald, Sarah M.;Patton, John T.
三层二十面体轮状病毒颗粒最内层的VP2核壳包裹着病毒基因组和RNA处理酶，包括依赖RNA的RNA聚合酶(VP1)。除了将VP1锚定在核心内外，VP2也是一个重要的辅因子，它触发聚合酶使用包装的正链RNA模板启动双链RNA(DsRNA)的合成。VP2的要求有效地将包装与基因组复制结合在一起，并确保VP1只在组装的前病毒粒子中制造dsRNA。然而，轮状病毒核壳蛋白激活病毒聚合酶的机制仍然知之甚少。在目前的研究中，我们试图阐明VP2区域对VP1介导的体外dsRNA合成至关重要。通过比较几种不同轮状病毒蛋白的功能，我们发现核壳蛋白对聚合酶的激活具有特异性。通过截断和嵌合体突变，我们证明了VP2氨基末端在每个5倍轴下形成一个十聚体的内部枢纽，在VP1的激活中发挥着重要但非特异性的作用。我们的结果表明，与聚合酶激活特异性相关的VP2残基位于核壳的内面，与氨基末端不同。基于这些发现，我们预测VP2的几个区域在轮状病毒核心组装和基因组复制的协同过程中参与聚合酶。
The innermost VP2 core shell of the triple-layered, icosahedral rotavirus particle surrounds the viral genome and RNA processing enzymes, including the RNA-dependent RNA polymerase (VP1). In addition to anchoring VP1 within the core, VP2 is also an essential cofactor that triggers the polymerase to initiate double-stranded RNA (dsRNA) synthesis using packaged plus-strand RNA templates. The VP2 requirement effectively couples packaging with genome replication and ensures that VP1 makes dsRNA only within an assembling previrion particle. However, the mechanism by which the rotavirus core shell protein activates the viral polymerase remains very poorly understood. In the current study, we sought to elucidate VP2 regions critical for VP1-mediated in vitro dsRNA synthesis. By comparing the functions of proteins from several different rotaviruses, we found that polymerase activation by the core shell protein is specific. Through truncation and chimera mutagenesis, we demonstrate that the VP2 amino terminus, which forms a decameric, internal hub underneath each 5-fold axis, plays an important but nonspecific role in VP1 activation. Our results indicate that the VP2 residues correlating with polymerase activation specificity are located on the inner face of the core shell, distinct from the amino terminus. Based on these findings, we predict that several regions of VP2 engage the polymerase during the concerted processes of rotavirus core assembly and genome replication.