Rahmeh, AmalMorin, BenjaminSchenk, AndreasLiang, BoHeinrich, BiancaBrusic, VesnaWalz, ThomasWhelan, Sean2019-10-052012Rahmeh, A. A., B. Morin, A. D. Schenk, B. Liang, B. S. Heinrich, V. Brusic, T. Walz, and S. P. J. Whelan. 2012. “Critical Phosphoprotein Elements That Regulate Polymerase Architecture and Function in Vesicular Stomatitis Virus.” Proceedings of the National Academy of Sciences 109 (36): 14628–33. https://doi.org/10.1073/pnas.1209147109.0027-84240744-28311091-6490http://nrs.harvard.edu/urn-3:HUL.InstRepos:41483552The RNA-dependent RNA polymerase (RdRP) of nonsegmented negative-sense RNA viruses consists of a large catalytic protein (L) and a phosphoprotein cofactor (P). During infection, the RdRP replicates and transcribes the viral genome, which resides inside an oligomer of nucleocapsid protein (N-RNA). The classical view of P as a cofactor for L assigns a primary role of P as a bridge mediating the access of L to the RNA template, whereby its N-terminal domain (P-NTD) binds L and its C-terminal domain (P-CTD) binds N-RNA. Recent biochemical and structural studies of a prototype nonsegmented negative-sense RNA virus, vesicular stomatitis virus, suggest a role for P beyond that of a mere physical link: P induces a structural rearrangement in L and stimulates polymerase processivity. In this study, we investigated the critical requirements within P mediating the functional interaction with L to form a fully functional RdRP. We analyzed the correlation between the impact of P on the conformation of L and its activity in RNA synthesis and the consequences of these events on RdRP function. We identified three separable elements of the P-NTD that are required for inducing the conformational rearrangement of L, stimulating polymerase processivity, and mediating transcription of the N-RNA. The functional interplay between these elements provides insight into the role of P as a dynamic player in the RNA synthesis machine, influencing essential aspects of polymerase structure and function.en-USJournal Article2019-10-0510.1073/pnas.1209147109