<br>杯状病毒 VP2 在受体接合后形成门户状组装体,Nature

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杯状病毒 VP2 在受体接合后形成门户状组装体
Nature ( IF 50.5 ) Pub Date : 2019-01-01 , DOI: 10.1038/s41586-018-0852-1
Michaela J Conley ₁ , Marion McElwee ₁ , Liyana Azmi ₂ , Mads Gabrielsen ₃ , Olwyn Byron ₄ , Ian G Goodfellow ₅ , David Bhella ₁

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为了引发感染，许多病毒在受体参与后通过触发内吞作用进入宿主细胞。然而，非包膜病毒逃避内体的机制知之甚少。在这里，我们展示了猫杯状病毒的近原子分辨率冷冻电子显微镜结构，这些结构均未修饰并用其细胞受体的可溶性片段（猫连接粘附分子 A）标记。我们表明 VP2 是一种由所有杯状病毒编码的小衣壳蛋白1,2，在受体参与后，在独特的三重对称轴上形成一个大的门户状组装体。这种组装体 - 在未修饰的病毒粒子中未检测到 - 由 VP2 的 12 个副本组成，它们的疏水 N 末端指向远离病毒粒子表面。门户网站站点的局部重排导致衣壳中孔的打开。我们假设门户状组装充当杯状病毒基因组通过内体膜递送到宿主细胞细胞质中的通道，从而引发感染。以前已知 VP2 对传染性病毒的产生至关重要3;猫杯状病毒及其细胞受体的冷冻电子显微镜结构显示，12 个拷贝的次要衣壳蛋白 VP2 形成一个门户状组装体，围绕衣壳中的一个孔排列。

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Calicivirus VP2 forms a portal-like assembly following receptor engagement

To initiate infection, many viruses enter their host cells by triggering endocytosis following receptor engagement. However, the mechanisms by which non-enveloped viruses escape the endosome are poorly understood. Here we present near-atomic-resolution cryo-electron microscopy structures for feline calicivirus both undecorated and labelled with a soluble fragment of its cellular receptor, feline junctional adhesion molecule A. We show that VP2, a minor capsid protein encoded by all caliciviruses1,2, forms a large portal-like assembly at a unique three-fold axis of symmetry, following receptor engagement. This assembly—which was not detected in undecorated virions—is formed of twelve copies of VP2, arranged with their hydrophobic N termini pointing away from the virion surface. Local rearrangement at the portal site leads to the opening of a pore in the capsid shell. We hypothesize that the portal-like assembly functions as a channel for the delivery of the calicivirus genome, through the endosomal membrane, into the cytoplasm of a host cell, thereby initiating infection. VP2 was previously known to be critical for the production of infectious virus3; our findings provide insights into its structure and function that advance our understanding of the Caliciviridae.Cryo-electron microscopy structures of feline calicivirus and its cellular receptor show that twelve copies of the minor capsid protein VP2 form a portal-like assembly arranged about a pore in the capsid shell.

更新日期：2019-01-01

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