Crystal structure of the RNA-dependent RNA polymerase from influenza C virus.
Crystal structure of the RNA-dependent RNA polymerase from influenza C virus.
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DOI：
10.1038/nature15525
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发表时间：
2015-11-05
期刊：
影响因子：
64.8
通讯作者：
Fodor E
中科院分区：
文献类型：
--
作者：
Hengrung N;El Omari K;Serna Martin I;Vreede FT;Cusack S;Rambo RP;Vonrhein C;Bricogne G;Stuart DI;Grimes JM;Fodor E
负义RNA病毒，如流感病毒，编码大的、多结构域RNA依赖性RNA聚合酶，其可以转录和复制病毒RNA基因组。在流感病毒中，聚合酶（FluPol）由三种多肽组成：PB 1、PB 2和PA/P3。PB 1容纳聚合酶活性位点，而PB 2和PA/P3分别含有通过帽抢夺进行转录起始所需的帽结合和核酸内切酶结构域。复制通过从头起始发生，并且涉及互补RNA中间体。甲型和B型流感病毒聚合酶的现有结构包括启动子RNA（病毒基因组片段的5′和3′末端），显示FluPol处于转录前起始状态。在这里，我们报告了来自C型流感病毒的apo-FluPol的结构，通过X射线晶体学解析到3.9 μ m，揭示了一种新的“闭合”构象。apo-FluPol形成了一个紧凑的颗粒，PB 1位于其中心，一面被PB 2覆盖，夹在P3的两个球状结构域之间。值得注意的是，这种结构与启动子结合的FluPol的结构完全不同。P3的核酸内切酶结构域和PB 2的羧基末端三分之二内的结构域完全重排。帽结合位点被PB 2封闭，导致与转录起始不相容的构象。因此，我们的结构在封闭的转录前激活状态下捕获FluPol。这揭示了感染细胞中新制备的apo-FluPol的构象，但也可能适用于非转录核糖核蛋白复合物背景下的FluPol。的apo-FluPol的结构与那些启动子结合的FluPol的比较，使我们能够提出一种机制的FluPol激活。我们的研究证明了流感病毒RNA聚合酶的显着灵活性，并帮助我们理解控制转录和基因组复制的机制。
Negative-sense RNA viruses, such as influenza, encode large, multidomain RNA-dependent RNA polymerases that can both transcribe and replicate the viral RNA genome. In influenza virus, the polymerase (FluPol) is composed of three polypeptides: PB1, PB2 and PA/P3. PB1 houses the polymerase active site, whereas PB2 and PA/P3 contain, respectively, cap-binding and endonuclease domains required for transcription initiation by cap-snatching. Replication occurs through de novo initiation and involves a complementary RNA intermediate. Currently available structures of the influenza A and B virus polymerases include promoter RNA (the 5′ and 3′ termini of viral genome segments), showing FluPol in transcription pre-initiation states. Here we report the structure of apo-FluPol from an influenza C virus, solved by X-ray crystallography to 3.9 Å, revealing a new ‘closed’ conformation. The apo-FluPol forms a compact particle with PB1 at its centre, capped on one face by PB2 and clamped between the two globular domains of P3. Notably, this structure is radically different from those of promoter-bound FluPols. The endonuclease domain of P3 and the domains within the carboxy-terminal two-thirds of PB2 are completely rearranged. The cap-binding site is occluded by PB2, resulting in a conformation that is incompatible with transcription initiation. Thus, our structure captures FluPol in a closed, transcription pre-activation state. This reveals the conformation of newly made apo-FluPol in an infected cell, but may also apply to FluPol in the context of a non-transcribing ribonucleoprotein complex. Comparison of the apo-FluPol structure with those of promoter-bound FluPols allows us to propose a mechanism for FluPol activation. Our study demonstrates the remarkable flexibility of influenza virus RNA polymerase, and aids our understanding of the mechanisms controlling transcription and genome replication.