ジャーナル: Nat Commun / 年: 2021 タイトル: Conformational changes in Lassa virus L protein associated with promoter binding and RNA synthesis activity. 著者: Tomas Kouba / Dominik Vogel / Sigurdur R Thorkelsson / Emmanuelle R J Quemin / Harry M Williams / Morlin Milewski / Carola Busch / Stephan Günther / Kay Grünewald / Maria Rosenthal / Stephen Cusack / 要旨: 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 ...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.