Using enzymatic assays, mass spectrometry, and cryo-EM structures, the authors demonstrate that SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) preferentially incorporates remdesivir triphosphate (RTP), outcompeting ATP; whereas, the S759A mutant confers RTP resistance by switching the preference to ATP. These findings will guide the design of future non-obligate nucleoside analogs to overcome resistance mechanisms.
- Calvin J. Gordon
- Mizar F. Oliva
- Kalyan Das
