Abstract
SummaryThe 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, we find no evidence that these ACE2-affinity-enhancing mutations have been selected in current SARS-CoV-2 pandemic isolates. We present an interactive visualization and open analysis pipeline to facilitate use of our dataset for vaccine design and functional annotation of mutations observed during viral surveillance.
Highlights
The SARS-related subgenus of betacoronaviruses comprises a diverse lineage of viruses that circulate in bat reservoirs and spill over into other mammalian species (Figure 1A; Bolles et al, 2011; Cui et al, 2019)
This platform enables receptor binding domain (RBD) expression on the cell surface of yeast (Figure 1B), where it can be assayed for ligand-binding affinity or protein expression levels, a close correlate of protein folding efficiency and stability (Kowalski et al, 1998a, 1998b; Shusta et al, 1999)
The yeast-expressed RBD from SARS-CoV-1 has similar antigenic and structural properties to the RBD expressed in mammalian cells (Chen et al, 2014, 2017, 2020a) and binds to angiotensin converting enzyme 2 (ACE2) as expected (Chen et al, 2014)
Summary
The SARS-related (sarbecovirus) subgenus of betacoronaviruses comprises a diverse lineage of viruses that circulate in bat reservoirs and spill over into other mammalian species (Figure 1A; Bolles et al, 2011; Cui et al, 2019). Sarbecoviruses initiate infection by binding to receptors on host cells via the viral spike protein. The entry receptor for both SARS-CoV-2 and the original SARS-CoV (which we refer to here as SARS-CoV-1) is the human cell-surface protein angiotensin converting enzyme 2 (ACE2). The receptor binding domain (RBD) of spike from both these viruses binds ACE2 with high affinity (Hoffmann et al, 2020; Letko et al, 2020; Li et al, 2003; Walls et al, 2020; Wrapp et al, 2020a). The RBD is the target of the most potent anti-SARS-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
