Chen James Z, Settembre Ethan C, Aoki Scott T, Zhang Xing, Bellamy A Richard, Dormitzer Philip R, Harrison Stephen C, Grigorieff Nikolaus
Rosenstiel Basic Medical Research Center, Brandeis University, Waltham, MA 02454, USA.
Proc Natl Acad Sci U S A. 2009 Jun 30;106(26):10644-8. doi: 10.1073/pnas.0904024106. Epub 2009 Jun 1.
Rotaviruses, major causes of childhood gastroenteritis, are nonenveloped, icosahedral particles with double-strand RNA genomes. By the use of electron cryomicroscopy and single-particle reconstruction, we have visualized a rotavirus particle comprising the inner capsid coated with the trimeric outer-layer protein, VP7, at a resolution (4 A) comparable with that of X-ray crystallography. We have traced the VP7 polypeptide chain, including parts not seen in its X-ray crystal structure. The 3 well-ordered, 30-residue, N-terminal "arms" of each VP7 trimer grip the underlying trimer of VP6, an inner-capsid protein. Structural differences between free and particle-bound VP7 and between free and VP7-coated inner capsids may regulate mRNA transcription and release. The Ca(2+)-stabilized VP7 intratrimer contact region, which presents important neutralizing epitopes, is unaltered upon capsid binding.
轮状病毒是儿童肠胃炎的主要病因，是一种无包膜的二十面体颗粒，具有双链RNA基因组。通过使用电子冷冻显微镜和单颗粒重建技术，我们已经观察到一个轮状病毒颗粒，其内部衣壳被三聚体外层蛋白VP7覆盖，分辨率（4埃）与X射线晶体学相当。我们已经追踪了VP7多肽链，包括在其X射线晶体结构中未见到的部分。每个VP7三聚体的3个排列有序、由30个残基组成的N端“臂”抓住了衣壳内蛋白VP6的下层三聚体。游离的和与颗粒结合的VP7之间以及游离的和被VP7覆盖的内衣壳之间的结构差异可能会调节mRNA的转录和释放。呈现重要中和表位的Ca(2+)稳定的VP7三聚体内接触区域在与衣壳结合后未发生改变。
