European Molecular Biology Laboratory, Grenoble, France.
Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
Nat Commun. 2021 Dec 2;12(1):7018. doi: 10.1038/s41467-021-27305-5.
Lassa virus is endemic in West Africa and can cause severe hemorrhagic fever. The viral L protein transcribes and replicates the RNA genome via its RNA-dependent RNA polymerase activity. Here, we present nine cryo-EM structures of the L protein in the apo-, promoter-bound pre-initiation and active RNA synthesis states. We characterize distinct binding pockets for the conserved 3' and 5' promoter RNAs and show how full-promoter binding induces a distinct pre-initiation conformation. In the apo- and early elongation states, the endonuclease is inhibited by two distinct L protein peptides, whereas in the pre-initiation state it is uninhibited. In the early elongation state, a template-product duplex is bound in the active site cavity together with an incoming non-hydrolysable nucleotide and the full C-terminal region of the L protein, including the putative cap-binding domain, is well-ordered. These data advance our mechanistic understanding of how this flexible and multifunctional molecular machine is activated.
拉萨病毒在西非流行，可引起严重的出血热。病毒 L 蛋白通过其 RNA 依赖的 RNA 聚合酶活性转录和复制 RNA 基因组。在这里，我们展示了 L 蛋白在无配体、启动子结合的起始前和活性 RNA 合成状态下的九个冷冻电镜结构。我们描述了对保守的 3' 和 5' 启动子 RNA 的不同结合口袋，并展示了如何通过完全启动子结合诱导独特的起始前构象。在无配体和早期延伸状态下，内切酶被两个不同的 L 蛋白肽抑制，而在起始前状态下它未被抑制。在早期延伸状态下，模板-产物双链与进入的非水解核苷酸一起结合在活性位点腔中，L 蛋白的完整 C 末端区域（包括假定的帽结合结构域）有序排列。这些数据推进了我们对这种灵活多功能分子机器如何被激活的机制理解。
