Université Grenoble Alpes, CNRS, CEA, Institute for Structural Biology (IBS), F-38000, Grenoble, France.
European Molecular Biology Laboratory, Grenoble, France.
Nat Commun. 2020 Jul 17;11(1):3590. doi: 10.1038/s41467-020-17349-4.
Bunyavirales is an order of segmented negative-strand RNA viruses comprising several life-threatening pathogens against which no effective treatment is currently available. Replication and transcription of the RNA genome constitute essential processes performed by the virally encoded multi-domain RNA-dependent RNA polymerase. Here, we describe the complete high-resolution cryo-EM structure of La Crosse virus polymerase. It reveals the presence of key protruding C-terminal domains, notably the cap-binding domain, which undergoes large movements related to its role in transcription initiation, and a zinc-binding domain that displays a fold not previously observed. We capture the polymerase structure at pre-initiation and elongation states, uncovering the coordinated movement of the priming loop, mid-thumb ring linker and lid domain required for the establishment of a ten-base-pair template-product RNA duplex before strand separation into respective exit tunnels. These structural details and the observed dynamics of key functional elements will be instrumental for structure-based development of polymerase inhibitors.
布尼亚病毒目是一类具有分段负链 RNA 基因组的病毒，其中包含几种目前尚无有效治疗方法的危及生命的病原体。病毒编码的多结构域 RNA 依赖性 RNA 聚合酶负责病毒 RNA 基因组的复制和转录，这是两个基本过程。在此，我们描述了拉各斯病毒聚合酶的完整高分辨率冷冻电镜结构。该结构揭示了关键突出的 C 末端结构域的存在，特别是帽结合结构域，它发生了与转录起始相关的较大运动，以及一个锌结合结构域，该结构域具有以前未观察到的折叠。我们捕获了聚合酶在起始前和延伸状态下的结构，揭示了引发环、中拇指环接头和盖子结构域的协调运动，这些运动对于在链分离到各自的出口隧道之前建立一个包含十个碱基对的模板-产物 RNA 双链体是必需的。这些结构细节和关键功能元件的观察到的动力学将对基于结构的聚合酶抑制剂的开发起到重要作用。
