Centre de Biochimie Structurale, 29 rue de Navacelles, 34090 Montpellier Cedex, France.
J Virol. 2010 May;84(9):4706-13. doi: 10.1128/JVI.02662-09. Epub 2010 Feb 24.
Cauliflower mosaic virus (CaMV) is transmitted from plant to plant through a seemingly simple interaction with insect vectors. This process involves an aphid receptor and two viral proteins, P2 and P3. P2 binds to both the aphid receptor and P3, itself tightly associated with the virus particle, with the ensemble forming a transmissible viral complex. Here, we describe the conformations of both unliganded CaMV P3 protein and its virion-associated form. X-ray crystallography revealed that the N-terminal domain of unliganded P3 is a tetrameric parallel coiled coil with a unique organization showing two successive four-stranded subdomains with opposite supercoiling handedness stabilized by a ring of interchain disulfide bridges. A structural model of virus-liganded P3 proteins, folding as an antiparallel coiled-coil network coating the virus surface, was derived from molecular modeling. Our results highlight the structural and biological versatility of this coiled-coil structure and provide new insights into the molecular mechanisms involved in CaMV acquisition and transmission by the insect vector.
花椰菜花叶病毒（CaMV）通过与昆虫载体的看似简单的相互作用在植物间传播。这个过程涉及一个蚜虫受体和两个病毒蛋白，P2 和 P3。P2 与蚜虫受体和 P3 本身结合，后者与病毒颗粒紧密相关，整个复合物形成可传播的病毒复合物。在这里，我们描述了未配位的 CaMV P3 蛋白及其病毒相关形式的构象。X 射线晶体学揭示，未配位 P3 的 N 端结构域是一个四聚体平行卷曲螺旋，具有独特的组织，显示两个连续的四链亚结构域，具有相反的超螺旋手性，由环链间二硫键稳定。病毒配体 P3 蛋白的结构模型，作为包裹病毒表面的反平行卷曲螺旋网络折叠，源自分子建模。我们的结果强调了这种卷曲螺旋结构的结构和生物学多功能性，并为涉及昆虫载体获取和传播 CaMV 的分子机制提供了新的见解。
