RT Journal Article SR Electronic T1 The temperature-dependent conformational ensemble of SARS-CoV-2 main protease (Mpro) JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.05.03.437411 DO 10.1101/2021.05.03.437411 A1 Ebrahim, Ali A1 Riley, Blake T. A1 Kumaran, Desigan A1 Andi, Babak A1 Fuchs, Martin R. A1 McSweeney, Sean A1 Keedy, Daniel A. YR 2021 UL http://biorxiv.org/content/early/2021/11/07/2021.05.03.437411.abstract AB The COVID-19 pandemic, instigated by the SARS-CoV-2 coronavirus, continues to plague the globe. The SARS-CoV-2 main protease, or Mpro, is a promising target for development of novel antiviral therapeutics. Previous X-ray crystal structures of Mpro were obtained at cryogenic temperature or room temperature only. Here we report a series of high-resolution crystal structures of unliganded Mpro across multiple temperatures from cryogenic to physiological, and another at high humidity. We interrogate these datasets with parsimonious multiconformer models, multi-copy ensemble models, and isomorphous difference density maps. Our analysis reveals a temperature-dependent conformational landscape for Mpro, including mobile solvent interleaved between the catalytic dyad, mercurial conformational heterogeneity in a key substrate-binding loop, and a far-reaching intramolecular network bridging the active site and dimer interface. Our results may inspire new strategies for antiviral drug development to counter-punch COVID-19 and combat future coronavirus pandemics.Synopsis X-ray crystallography at variable temperature for SARS-CoV-2 Mpro reveals a complex conformational landscape, including mobile solvent at the catalytic dyad, mercurial conformational heterogeneity in a key substrate-binding loop, and an intramolecular network bridging the active site and dimer interface.Competing Interest StatementThe authors have declared no competing interest.Fo-Foisomorphous difference electron density mapCOVID-19coronavirus disease 2019SARS-CoV-2severe acute respiratory syndrome coronavirus 2MproSARS coronavirus main protease