Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.
J Virol. 2013 May;87(9):4818-25. doi: 10.1128/JVI.03508-12. Epub 2013 Feb 13.
The major capsid protein of norovirus VP1 assembles to form an icosahedral viral particle. Despite evidence that the Norwalk virus (NV) minor structural protein VP2 is present in infectious virions, the available crystallographic and electron cryomicroscopy structures of NV have not revealed the location of VP2. In this study, we determined that VP1 associates with VP2 at the interior surface of the capsid, specifically with the shell (S) domain of VP1. We mapped the interaction site to amino acid 52 of VP1, an isoleucine located within a sequence motif IDPWI in the S domain that is highly conserved across norovirus genogroups. Mutation of this isoleucine abrogated VP2 incorporation into virus-like particles without affecting the ability for VP1 to dimerize and form particles. The highly basic nature of VP2 and its location interior to the viral particle are consistent with its potential role in assisting capsid assembly and genome encapsidation.
诺如病毒 VP1 的主要衣壳蛋白组装形成二十面体病毒颗粒。尽管有证据表明诺如病毒（NV）的次要结构蛋白 VP2 存在于传染性病毒粒子中，但 NV 的现有晶体学和电子 cryomicroscopy 结构并未揭示 VP2 的位置。在这项研究中，我们确定 VP1 与衣壳内部表面的 VP2 结合，特别是与 VP1 的壳（S）结构域结合。我们将相互作用位点映射到 VP1 的 52 位氨基酸，该位置是 S 结构域中一个高度保守的 IDPWI 序列基序内的异亮氨酸，该基序跨越诺如病毒属。该异亮氨酸的突变消除了 VP2 掺入病毒样颗粒，而不影响 VP1 二聚化和形成颗粒的能力。VP2 的高度碱性及其在病毒粒子内部的位置与其在协助衣壳组装和基因组包裹中的潜在作用一致。
