Structural Basis for Helicase-Polymerase Coupling in the SARS-CoV-2 Replication-Transcription Complex.
Chen, J., Malone, B., Llewellyn, E., Grasso, M., Shelton, P.M.M., Olinares, P.D.B., Maruthi, K., Eng, E.T., Vatandaslar, H., Chait, B.T., Kapoor, T.M., Darst, S.A., Campbell, E.A.(2020) Cell 182: 1560-1573.e13
- PubMed: 32783916 
- DOI: https://doi.org/10.1016/j.cell.2020.07.033
- Primary Citation of Related Structures:  
6XEZ - PubMed Abstract: 
SARS-CoV-2 is the causative agent of the 2019-2020 pandemic. The SARS-CoV-2 genome is replicated and transcribed by the RNA-dependent RNA polymerase holoenzyme (subunits nsp7/nsp8 2 /nsp12) along with a cast of accessory factors. One of these factors is the nsp13 helicase. Both the holo-RdRp and nsp13 are essential for viral replication and are targets for treating the disease COVID-19. Here we present cryoelectron microscopic structures of the SARS-CoV-2 holo-RdRp with an RNA template product in complex with two molecules of the nsp13 helicase. The Nidovirales order-specific N-terminal domains of each nsp13 interact with the N-terminal extension of each copy of nsp8. One nsp13 also contacts the nsp12 thumb. The structure places the nucleic acid-binding ATPase domains of the helicase directly in front of the replicating-transcribing holo-RdRp, constraining models for nsp13 function. We also observe ADP-Mg 2+ bound in the nsp12 N-terminal nidovirus RdRp-associated nucleotidyltransferase domain, detailing a new pocket for anti-viral therapy development.
Organizational Affiliation: 
Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA.