改变 N 端β-六聚体结构的雀麦花叶病毒衣壳蛋白的包装和结构表型。

Packaging and structural phenotype of brome mosaic virus capsid protein with altered N-terminal β-hexamer structure.

机构信息

Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521-0122, USA.

出版信息

Virology. 2011 Oct 10;419(1):17-23. doi: 10.1016/j.virol.2011.07.016. Epub 2011 Aug 23.

DOI:10.1016/j.virol.2011.07.016

Abstract

The first 45 amino acid region of brome mosaic virus (BMV) capsid protein (CP) contains RNA binding and structural domains that are implicated in the assembly of infectious virions. One such important structural domain encompassing amino acids 28QPVIV32, highly conserved between BMV and cowpea chlorotic mottle virus (CCMV), exhibits a β-hexamer structure. In this study we report that alteration of the β-hexamer structure by mutating 28QPVIV32 to 28AAAAA32 had no effect either on symptom phenotype, local and systemic movement in Chenopodium quinoa and RNA profile of in vivo assembled virions. However, sensitivity to RNase and assembly phenotypes distinguished virions assembled with CP subunits having β-hexamer from those of wild type. A comparison of 3-D models obtained by cryo electron microscopy revealed overall similar structural features for wild type and mutant virions, with small but significant differences near the 3-fold axes of symmetry.

摘要

雀麦花叶病毒（BMV）外壳蛋白（CP）的前 45 个氨基酸区域包含与组装感染性病毒粒子有关的 RNA 结合和结构域。CP 氨基酸 28QPVIV32 到 32 之间的这样一个重要结构域，在 BMV 和豇豆花叶病毒（CCMV）之间高度保守，表现出β-六聚体结构。在这项研究中，我们报告说，通过将 28QPVIV32 突变为 28AAAAA32 来改变β-六聚体结构，对症状表型、藜的局部和系统运动以及体内组装病毒粒子的 RNA 谱均没有影响。然而，对 RNase 的敏感性和组装表型将具有β-六聚体的 CP 亚基组装的病毒粒子与野生型病毒粒子区分开来。通过冷冻电子显微镜获得的 3-D 模型的比较表明，野生型和突变型病毒粒子具有总体相似的结构特征，在 3 倍对称轴附近存在微小但显著的差异。