Deep Mutational Scanning of SARS-CoV-2 Receptor Binding Domain Reveals Constraints on Folding and ACE2 Binding

The receptor binding domain (RBD) of the SARS-CoV-2 spike glycoprotein mediates viral attachment to ACE2 receptor and is a major determinant of host range and a dominant target of neutralizing antibodies. Here, we experimentally measure how all amino acid mutations to the RBD affect expression of folded protein and its affinity for ACE2. Most mutations are deleterious for RBD expression and ACE2 binding, and we identify constrained regions on the RBD's surface that may be desirable targets for vaccines and antibody-based therapeutics. But a substantial number of mutations are well tolerated or even enhance ACE2 binding, including at ACE2 interface residues that vary across SARS-related coronaviruses. However,…

• HH
  Howard Hughes Medical Institute
• BW
  Burroughs Wellcome Fund
• BA
  Bill and Melinda Gates Foundation
• PC
  Pew Charitable Trusts
• DR
  Damon Runyon Cancer Research Foundation
• WR
  Washington Research Foundation
• OP
  Open Philanthropy Project
• FG
  Fast Grants
• NI
  National Institute of General Medical Sciences
• DO
  Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases