Influenza viruses rely on an RNA-dependent RNA polymerase, sometimes known as FluPol (comprising PB1, PB2 and P3 subunits), that both transcribes and replicates the viral RNA genome. Transcription initiation occurs by cap-snatching and depends on a viral RNA (vRNA) promoter; all currently available FluPol structures reflect this transcription pre-initiation state, with vRNA bound to FluPol. Now, Hengrung et al. report a new FluPol structure without vRNA. This structure reveals a novel 'closed' conformation in which the central PB1 subunit (which houses the polymerase active site) is capped on one end by PB2 and clamped between the two globular domains of P3. Notably, the cap-binding domain of PB2 is occluded in this closed state, suggesting that binding of the vRNA is responsible for substantial conformational changes that induce the transition of FluPol to the 'opened' transcription pre-initiation state.
References
Hengrung, N. et al. Crystal structure of the RNA-dependent RNA polymerase from influenza C virus. Nature http://dx.doi.org/10.1038/nature15525 (2015)
Rights and permissions
About this article
Cite this article
Nunes-Alves, C. Highly flexible influenza polymerase. Nat Rev Microbiol 13, 738 (2015). https://doi.org/10.1038/nrmicro3593
Published:
Issue Date:
DOI: https://doi.org/10.1038/nrmicro3593