tetano
Editor, Senior Moderator
J Virol. 2017 Jan 25. pii: JVI.02467-16. doi: 10.1128/JVI.02467-16. [Epub ahead of print]
[h=1]The role of the PB2 627-domain in influenza A virus polymerase function.[/h] Nilsson BE[SUP]1[/SUP], Te Velthuis AJ[SUP]1,[/SUP][SUP]2[/SUP], Fodor E[SUP]3[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] The RNA genome of influenza A viruses is transcribed and replicated by the viral RNA-dependent RNA polymerase composed of the subunits PA, PB1 and PB2. High-resolution structural data revealed that the polymerase assembles into a central polymerase core and several auxiliary highly flexible, protruding domains. The auxiliary PB2 cap-binding and the PA endonuclease domains are both involved in cap-snatching, but the role of the auxiliary PB2 627-domain, implicated in host range restriction of influenza A viruses, is still poorly understood. Here we use structure-guided truncations of the PB2 subunit to show that a PB2 subunit lacking the 627-domain accumulates in the cell nucleus and assembles into a heterotrimeric polymerase with PB1 and PA. Furthermore, we show that a recombinant viral polymerase lacking the PB2 627-domain is able to carry out cap-snatching, cap-dependent transcription initiation as well as cap-independent ApG dinucleotide extension in vitro, indicating that the PB2 627-domain of the influenza virus RNA polymerase is not involved in core catalytic functions of the polymerase. However, in a cellular context, the 627-domain is essential for both transcription and replication. In particular, we show that the PB2 627-domain is essential for the accumulation of the cRNA replicative intermediate in infected cells. Together, these results further our understanding of the role of the PB2 627-domain in transcription and replication of the influenza virus RNA genome.
[h=4]IMPORTANCE:[/h] Influenza A viruses are a major global health threat, not only causing disease in both humans and birds, but also placing significant strains on economies worldwide. Avian influenza A virus polymerases typically do not function efficiently in mammalian hosts and require adaptive mutations to restore polymerase activity. These adaptations include mutations in the 627-domain of the PB2 subunit of the viral polymerase, but it still remains to be established how these mutations enable host adaptation on a molecular level. In this study we characterise the role of the 627-domain in polymerase function and offer insights into the replication mechanism of influenza A viruses.
Copyright ? 2017 Nilsson et al.
PMID: 28122973 DOI: 10.1128/JVI.02467-16
[PubMed - as supplied by publisher]
[h=1]The role of the PB2 627-domain in influenza A virus polymerase function.[/h] Nilsson BE[SUP]1[/SUP], Te Velthuis AJ[SUP]1,[/SUP][SUP]2[/SUP], Fodor E[SUP]3[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] The RNA genome of influenza A viruses is transcribed and replicated by the viral RNA-dependent RNA polymerase composed of the subunits PA, PB1 and PB2. High-resolution structural data revealed that the polymerase assembles into a central polymerase core and several auxiliary highly flexible, protruding domains. The auxiliary PB2 cap-binding and the PA endonuclease domains are both involved in cap-snatching, but the role of the auxiliary PB2 627-domain, implicated in host range restriction of influenza A viruses, is still poorly understood. Here we use structure-guided truncations of the PB2 subunit to show that a PB2 subunit lacking the 627-domain accumulates in the cell nucleus and assembles into a heterotrimeric polymerase with PB1 and PA. Furthermore, we show that a recombinant viral polymerase lacking the PB2 627-domain is able to carry out cap-snatching, cap-dependent transcription initiation as well as cap-independent ApG dinucleotide extension in vitro, indicating that the PB2 627-domain of the influenza virus RNA polymerase is not involved in core catalytic functions of the polymerase. However, in a cellular context, the 627-domain is essential for both transcription and replication. In particular, we show that the PB2 627-domain is essential for the accumulation of the cRNA replicative intermediate in infected cells. Together, these results further our understanding of the role of the PB2 627-domain in transcription and replication of the influenza virus RNA genome.
[h=4]IMPORTANCE:[/h] Influenza A viruses are a major global health threat, not only causing disease in both humans and birds, but also placing significant strains on economies worldwide. Avian influenza A virus polymerases typically do not function efficiently in mammalian hosts and require adaptive mutations to restore polymerase activity. These adaptations include mutations in the 627-domain of the PB2 subunit of the viral polymerase, but it still remains to be established how these mutations enable host adaptation on a molecular level. In this study we characterise the role of the 627-domain in polymerase function and offer insights into the replication mechanism of influenza A viruses.
Copyright ? 2017 Nilsson et al.
PMID: 28122973 DOI: 10.1128/JVI.02467-16
[PubMed - as supplied by publisher]