Viruses are molecular machines sustained through a life cycle that requires replication within host cells. Throughout the infectious cycle, viral and cellular components interact to advance the multistep process required to produce progeny virions. Despite progress made in understanding the virus–host protein interactome, much remains to be discovered about the cellular factors that function during infection, especially those operating at terminal steps in replication. In an RNA interference screen, we identified the eukaryotic chaperonin T-complex protein-1 (TCP-1) ring complex (TRiC; also called CCT for chaperonin containing TCP-1) as a cellular factor required for late events in the replication of mammalian reovirus. We discovered that TRiC functions in reovirus replication through a mechanism that involves folding the viral σ3 major outer-capsid protein into a form capable of assembling onto virus particles. TRiC also complexes with homologous capsid proteins of closely related viruses. Our data define a critical function for TRiC in the viral assembly process and raise the possibility that this mechanism is conserved in related non-enveloped viruses. These results also provide insight into TRiC protein substrates and establish a rationale for the development of small-molecule inhibitors of TRiC as potential antiviral therapeutics.
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This work was supported in part by Public Health Service awards AI032539, AI122563, GM007347, UL1TR000445, and the Vanderbilt Lamb Center for Pediatric Research. The RNAi screen was performed in the Vanderbilt high-throughput screening facility, which is an institutionally supported core. Confocal images were captured in the cell imaging core at the Rangos Research Center at Children’s Hospital of Pittsburgh of UPMC. The authors thank P. Aravamudhan, J. Brown, B. Mainou, L. Silva, D. Sutherland and G. Taylor of the Dermody lab for essential discussions and critically editing the manuscript.
J.J.K. conceived, designed experiments and performed experiments, analysed data, contributed materials/analysis tools and wrote the paper. T.S.D. conceived and designed experiments, analysed the data and wrote the paper. I.F.C., A.W.A. and P.F.Z. conceived, designed experiments and performed experiments, and analysed data. J.A.B. conceived and designed experiments and performed experiments. D.R.G, J.F. and C.R. conceived and designed experiments, analysed data, and contributed materials/analysis tools. J.C.F. analysed data. All authors reviewed, critiqued and provided comments on the manuscript.
The authors declare no competing interests.
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Knowlton, J.J., Fernández de Castro, I., Ashbrook, A.W. et al. The TRiC chaperonin controls reovirus replication through outer-capsid folding. Nat Microbiol 3, 481–493 (2018). https://doi.org/10.1038/s41564-018-0122-x
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