Structural rearrangements in the phage head-to-tail interface during assembly and infection
Structural rearrangements in the phage head-to-tail interface during assembly and infection
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DOI：
10.1073/pnas.1504039112
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发表时间：
2015-06-02
影响因子：
11.1
通讯作者：
Orlova, Elena V.
中科院分区：
文献类型：
--
作者：
Chaban, Yuriy;Lurz, Rudi;Orlova, Elena V.
许多二十面体病毒使用一个特殊的门户顶点来控制基因组的封装和从病毒衣壳中释放。在尾随噬菌体中，入口系统连接到一个尾部结构，该尾部结构为基因组输送到宿主细胞提供了管道。据我们所知，我们首次报道了完整的门户-噬菌体尾部界面的亚纳米结构，它模拟了噬菌体感染期间DNA释放前后的状态。他们揭示了与密切的蛋白质-DNA相互作用相关的结构重排。噬菌体SPP1的门户蛋白GP6在与DNA相互作用的过程中，其中央通道的结构元件发生了协同重组。蛋白质-蛋白质相互作用网络启动蛋白质gp15和gp16的连续结合，以延长和关闭该通道。这一防止衣壳基因组泄漏的关键步骤是通过一种以前未知的变构机制实现的：gp16与GP15的两个不同区域结合，驱动内部gp16环的正确定位和折叠，以与其他gp16亚基的对等环相互作用。这些环合在一起，形成了一个塞子，关闭了通道。然后，Gp16将尾巴固定，产生具有感染性的病毒粒子。把关系统在感染开始时为病毒基因组退出打开，但在感染后重新关闭，这表明一种类似分子膜片的机制来控制DNA外流。这里描述的控制病毒组装和感染过程中噬菌体基因组运动的基本步骤的机制，很可能在生物圈中最大的病毒群--长尾噬菌体中保守。
Many icosahedral viruses use a specialized portal vertex to control genome encapsidation and release from the viral capsid. In tailed bacteriophages, the portal system is connected to a tail structure that provides the pipeline for genome delivery to the host cell. We report the first, to our knowledge, subnanometer structures of the complete portal-phage tail interface that mimic the states before and after DNA release during phage infection. They uncover structural rearrangements associated with intimate protein-DNA interactions. The portal protein gp6 of bacteriophage SPP1 undergoes a concerted reorganization of the structural elements of its central channel during interaction with DNA. A network of protein-protein interactions primes consecutive binding of proteins gp15 and gp16 to extend and close the channel. This critical step that prevents genome leakage from the capsid is achieved by a previously unidentified allosteric mechanism: gp16 binding to two different regions of gp15 drives correct positioning and folding of an inner gp16 loop to interact with equivalent loops of the other gp16 subunits. Together, these loops build a plug that closes the channel. Gp16 then fastens the tail to yield the infectious virion. The gatekeeper system opens for viral genome exit at the beginning of infection but recloses afterward, suggesting a molecular diaphragm-like mechanism to control DNA efflux. The mechanisms described here, controlling the essential steps of phage genome movements during virus assembly and infection, are likely to be conserved among long-tailed phages, the largest group of viruses in the Biosphere.