Rapid Profiling of the Glycosylation Effects on the Binding of SARS-CoV-2 Spike Protein to Angiotensin-Converting Enzyme 2 Using MALDI-MS with High Mass Detection

The spike protein receptor-binding domain (RBD) of SARS-CoV-2 binds directly to angiotensin-converting enzyme 2 (ACE2), mediating the host cell entry of SARS-CoV-2. Both spike protein and ACE2 are highly glycosylated, which can regulate the binding. Here, we utilized high-mass MALDI-MS with chemical cross-linking for profiling the glycosylation effects on the binding between RBD and ACE2. Overall, it was found that ACE2 glycosylation affects the binding more strongly than does RBD glycosylation. The binding affinity was improved after desialylation or partial deglycosylation (N690) of ACE2, while it decreased after degalactosylation. ACE2 can form dimers in solution, which bind more tightly to the RBD than the ACE2 monomers. The ACE2 dimerization and the binding of RBD to dimeric ACE2 can also be improved by the desialylation or deglycosylation of ACE2. Partial deglycosylation of ACE2 increased the dimerization of ACE2 and the binding affinity of RBD and ACE2 by more than a factor of 2, suggesting its high potential for neutralizing SARS-CoV-2. The method described in the work provided a simple way to analyze the protein-protein interaction without sample purification. It can be widely used for rapid profiling of glycosylation effects on protein-protein interaction for glycosylation-related diseases and the study of multiple interactions between protein and protein aggregates in a single system.