Viral proteins are frequently multifunctional to accommodate the high density of information encoded in viral genomes. Matrix (M) protein of negative-stranded RNA viruses such as Rhabdoviridae is one such example. Its primary function is virus assembly/budding but it is also involved in the switch from viral transcription to replication and the concomitant down regulation of host gene expression. In this study we undertook a search for potential rabies virus (RV) M protein's cellular partners. In a yeast two-hybrid screen the eIF3h subunit was identified as an M-interacting cellular factor, and the interaction was validated by co-immunoprecipitation and surface plasmon resonance assays. Upon expression in mammalian cell cultures, RV M protein was localized in early small ribosomal subunit fractions. Further, M protein added in trans inhibited in vitro translation on mRNA encompassing classical (Kozak-like) 5′-UTRs. Interestingly, translation of hepatitis C virus IRES-containing mRNA, which recruits eIF3 via a different noncanonical mechanism, was unaffected. Together, the data suggest that, as a complement to its functions in virus assembly/budding and regulation of viral transcription, RV M protein plays a role in inhibiting translation in virus-infected cells through a protein-protein interaction with the cellular translation machinery.
Bibliographical noteFunding Information:
We thank Richard Jackson and Sarah Hunt for rabbit antibodies directed against unr. We are grateful to Richard Jackson and Ivan Shatsky for helpful discussions. We thank Michel Favre and Robin Fahraeus and people from their laboratories for kindly supporting this work. This work was supported in part by funding from the Pasteur Institute, work in K.M.K’s laboratory is supported by grants from ANRS and INSERM. J.W.B.H. holds grant GM22135 from NIH. A.K. was funded by the FRM and E. R. was a recipient of a M.E.N.R.T fellowship. Funding to pay the Open Access publication charge was provided by ARNS grant of K.M.K0s laboratory.