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Association of the influenza virus RNA polymerase subunit PB2 with the host chaperonin CCT.

ABSTRACT: The RNA polymerase of influenza A virus is a host range determinant and virulence factor. In particular, the PB2 subunit of the RNA polymerase has been implicated as a crucial factor that affects cell tropism as well as virulence in animal models. These findings suggest that host factors associating with the PB2 protein may play an important role during viral replication. In order to identify host factors that associate with the PB2 protein, we purified recombinant PB2 from transiently transfected mammalian cells and identified copurifying host proteins by mass spectrometry. We found that the PB2 protein associates with the cytosolic chaperonin containing TCP-1 (CCT), stress-induced phosphoprotein 1 (STIP1), FK506 binding protein 5 (FKBP5), alpha- and beta-tubulin, Hsp60, and mitochondrial protein p32. Some of these binding partners associate with each other, suggesting that PB2 might interact with these proteins in multimeric complexes. More detailed analysis of the interaction of the PB2 protein with CCT revealed that PB2 associates with CCT as a monomer and that the CCT binding site is located in a central region of the PB2 protein. PB2 proteins from various influenza virus subtypes and origins can associate with CCT. Silencing of CCT resulted in reduced viral replication and reduced PB2 protein and viral RNA accumulation in a ribonucleoprotein reconstitution assay, suggesting an important function for CCT during the influenza virus life cycle. We propose that CCT might be acting as a chaperone for PB2 to aid its folding and possibly its incorporation into the trimeric RNA polymerase complex.

SUBMITTER: Fislova T

PROVIDER: S-EPMC2919027 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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Association of the influenza virus RNA polymerase subunit PB2 with the host chaperonin CCT.

Fislová Tatiana T Thomas Benjamin B Graef Katy M KM Fodor Ervin E

Journal of virology 20100623 17

The RNA polymerase of influenza A virus is a host range determinant and virulence factor. In particular, the PB2 subunit of the RNA polymerase has been implicated as a crucial factor that affects cell tropism as well as virulence in animal models. These findings suggest that host factors associating with the PB2 protein may play an important role during viral replication. In order to identify host factors that associate with the PB2 protein, we purified recombinant PB2 from transiently transfect ...[more]

PMID: 20573828

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Project description:Understanding how avian influenza viruses adapt to human hosts is critical for the monitoring and prevention of future pandemics. Host specificity is determined by multiple sites in different viral proteins, and mutation of only a limited number of these sites can lead to inter-species transmission. Several of these sites have been identified in the viral polymerase, the best characterised being position 627 in the PB2 subunit. Efficient viral replication at the relatively low temperature of the human respiratory tract requires lysine 627 rather than the glutamic acid variant found systematically in avian viruses. However, the molecular mechanism by which any of these host specific sites determine host range are unknown, although adaptation to host factors is frequently evoked. We used ESPRIT, a library screening method, to identify a new PB2 domain that contains a high density of putative host specific sites, including residue 627. The X-ray structure of this domain (denoted the 627-domain) exhibits a novel fold with the side-chain of Lys627 solvent exposed. The structure of the K627E mutated domain shows no structural differences but the charge reversal disrupts a striking basic patch on the domain surface. Five other recently proposed host determining sites of PB2 are also located on the 627-domain surface. The structure of the complete C-terminal region of PB2 comprising the 627-domain and the previously identified NLS-domain, which binds the host nuclear import factor importin alpha, was also determined. The two domains are found to pack together with a largely hydrophilic interface. These data enable a three-dimensional mapping of approximately half of PB2 sites implicated in cross-species transfer onto a single structural unit. Their surface location is consistent with roles in interactions with other viral proteins or host factors. The identification and structural characterization of these well-defined PB2 domains will help design experiments to elucidate the effects of mutations on polymerase-host factor interactions.

Dataset Information

Association of the influenza virus RNA polymerase subunit PB2 with the host chaperonin CCT.

Publications

Association of the influenza virus RNA polymerase subunit PB2 with the host chaperonin CCT.

Similar Datasets

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