The novel asymmetric entry intermediate of a picornavirus captured with nanodiscs.
The novel asymmetric entry intermediate of a picornavirus captured with nanodiscs.
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DOI：
10.1126/sciadv.1501929
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发表时间：
2016-08
期刊：
影响因子：
13.6
通讯作者：
Hafenstein S
中科院分区：
文献类型：
--
作者：
Lee H;Shingler KL;Organtini LJ;Ashley RE;Makhov AM;Conway JF;Hafenstein S
用作模拟膜的纳米圆盘捕获了经历全局和局部变化以进入宿主细胞的小核糖核酸病毒。许多无包膜病毒与宿主受体结合，引发基因组释放所需的衣壳构象变化。小核糖核酸病毒进入机制的结构研究依赖于在高温下或与过量受体分子一起孵育的病毒的体外方法，以触发进入中间体或A-粒子。我们通过嵌入脂质双层纳米盘中的全长受体触发病毒，诱导了柯萨奇病毒 B3 进入中间体。使用冷冻电子显微镜和直接电子探测器重建这些不对称形成的 A 粒子。这些在具有和不具有二十面体对称性（分别为 3.9 和 7.8 Å）的膜上捕获的小核糖核酸病毒进入中间体的第一个高分辨率结构揭示了一种与经典 A 粒子明显不同的新型 A 粒子。不对称受体结合触发最小的整体衣壳扩张，但在受体相互作用位点发生显着的局部构象变化。此外，病毒蛋白仅在邻近纳米盘的广泛蛋白质重塑位点从衣壳中挤出。因此，受体的结合触发独特位点的形成，为基因组释放做准备。
Nanodiscs used as a mock membrane captured a picornavirus undergoing global and local changes to enter host cells. Many nonenveloped viruses engage host receptors that initiate capsid conformational changes necessary for genome release. Structural studies on the mechanisms of picornavirus entry have relied on in vitro approaches of virus incubated at high temperatures or with excess receptor molecules to trigger the entry intermediate or A-particle. We have induced the coxsackievirus B3 entry intermediate by triggering the virus with full-length receptors embedded in lipid bilayer nanodiscs. These asymmetrically formed A-particles were reconstructed using cryo-electron microscopy and a direct electron detector. These first high-resolution structures of a picornavirus entry intermediate captured at a membrane with and without imposing icosahedral symmetry (3.9 and 7.8 Å, respectively) revealed a novel A-particle that is markedly different from the classical A-particles. The asymmetric receptor binding triggers minimal global capsid expansion but marked local conformational changes at the site of receptor interaction. In addition, viral proteins extrude from the capsid only at the site of extensive protein remodeling adjacent to the nanodisc. Thus, the binding of the receptor triggers formation of a unique site in preparation for genome release.