The Spike (S) protein is the main handle for SARS-CoV-2 to enter host cells via surface ACE2 receptors. How ACE2 binding activates proteolysis of S protein is unknown. Here, using amide hydrogen-deuterium exchange mass spectrometry and molecular dynamics simulations, we have mapped the S:ACE2 interaction interface and uncovered long-range allosteric propagation of ACE2 binding to sites necessary for host-mediated proteolysis of S protein, critical for viral host entry. Unexpectedly, ACE2 binding enhances dynamics at a distal S1/S2 cleavage site and flanking protease docking site ~27 Å away while dampening dynamics of the stalk hinge (central helix and heptad repeat) regions ~130 Å away. This highlights that the stalk and proteolysis sites of the S protein are dynamic hotspots in the pre-fusion state. Our findings provide a dynamics map of the S:ACE2 interface in solution and also offer mechanistic insights into how ACE2 binding is allosterically coupled to distal proteolytic processing sites and viral-host membrane fusion. Our findings highlight protease docking sites flanking the S1/S2 cleavage site, fusion peptide and heptad repeat 1 (HR1) as alternate allosteric hotspot targets for potential therapeutic development.
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2, 3, 4 and 5.
- Ganesh Srinivasan Anand
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Donald Hamelberg, Georgia State University, United States
© 2021, Raghuvamsi et al.
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