Residue-level Insights into the ATP-dependent Translocation Mechanisms of RNA-Viral Helicases

11:00am

MRB 202 Conference Room 

Martin McCullagh (Assistant Professor, Department of Chemistry, Oklahoma State University)

Helicases of RNA viruses perform pivotal functions during RNA viral replication and are thus appealing targets for antiviral development.  Orthosteric inhibitors of these enzymes, however, suffer from a lack of specificity making it critical to identify non-orthosteric regions of importance. To explore the ATP-dependent translocation mechanisms of viral helicases, the McCullagh group uses molecular simulations of the enzyme in all relevant substrate states coupled with state-of-the-art analyses to identify functionally important regions.  For Dengue virus NS3 helicase, our simulations and analyses identified Motif V as a communication hub between the ATP pocket and RNA cleft. Our experimental collaborators used mutagenesis and an RNA unwinding assay to corroborate this finding and further characterize Motif V as a helicase throttle. Interestingly, simulations of SARS-CoV-2 nsp13, a helicase from a different superfamily, indicate that Motif V plays a similar role in the mechanism of this enzyme. Additionally, simulations of Zika and West Nile NS3 indicate two important regions of RNA-dependent allostery in the ATP pocket. Combined, our results identify three non-orthosteric regions of importance in helicases of RNA viruses that could be targeted for antiviral development.