Structural highlights
Function
[PA_INCJH] Implicated in endonuclease cleavage of capped RNA primers. Displays an elongation factor activity in viral RNA synthesis. Dispensable for viral transcription, but not replication (By similarity). [PB2_INCJH] Involved in transcription initiation and cap-stealing mechanism, in which cellular capped pre-mRNA are used to generate primers for viral transcription. Binds the cap of the target pre-RNA which is subsequently cleaved by PB1 (By similarity). [RDRP_INCJH] RNA-dependent RNA polymerase which is responsible for replication and transcription of virus segments. Binds the promoter sequence of the encapsidated viral RNA. Displays an endonuclease activity involved in cap-stealing. Cleaves cellular pre-mRNA to generate primers for viral transcription (By similarity).
Publication Abstract from PubMed
Influenza virus RNA polymerase (FluPol), a heterotrimer composed of PB1, PB2, and PA subunits (P3 in influenza C), performs both transcription and replication of the viral RNA genome. For transcription, FluPol interacts with the C-terminal domain (CTD) of RNA polymerase II (Pol II), which enables FluPol to snatch capped RNA primers from nascent host RNAs. Here, we describe the co-crystal structure of influenza C virus polymerase (FluPolC) bound to a Ser5-phosphorylated CTD (pS5-CTD) peptide. The position of the CTD-binding site at the interface of PB1, P3, and the flexible PB2 C-terminal domains suggests that CTD binding stabilizes the transcription-competent conformation of FluPol. In agreement, both cap snatching and capped primer-dependent transcription initiation by FluPolC are enhanced in the presence of pS5-CTD. Mutations of amino acids in the CTD-binding site reduce viral mRNA synthesis. We propose a model for the activation of the influenza virus transcriptase through its association with pS5-CTD of Pol II.
A Mechanism for the Activation of the Influenza Virus Transcriptase.,Serna Martin I, Hengrung N, Renner M, Sharps J, Martinez-Alonso M, Masiulis S, Grimes JM, Fodor E Mol Cell. 2018 Jun 21;70(6):1101-1110.e4. doi: 10.1016/j.molcel.2018.05.011. Epub, 2018 Jun 14. PMID:29910112[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Serna Martin I, Hengrung N, Renner M, Sharps J, Martinez-Alonso M, Masiulis S, Grimes JM, Fodor E. A Mechanism for the Activation of the Influenza Virus Transcriptase. Mol Cell. 2018 Jun 21;70(6):1101-1110.e4. doi: 10.1016/j.molcel.2018.05.011. Epub, 2018 Jun 14. PMID:29910112 doi:http://dx.doi.org/10.1016/j.molcel.2018.05.011
