Key galactosylated glycan receptors of SARS-CoV-2 and its inhibitor from bovine milk galactosylated glycoproteins

Illustrating the precise role of glycosylation in the interaction of spike (S) protein of SARS-CoV-2 and angiotensin-converting enzyme 2 (ACE2) is important for understanding molecular mechanism of SARS-COV-2 infection. In this study, we utilized the antibody-overlay lectin microarrays, molecular docking analysis and glycosidase digestion to probe roles of N-glycans on S1 subunit of SARS-CoV-2 and ACE2. Our results showed that the galactosylated glycans were dominant on both S protein and ACE2. Importantly, we proved that the β1-4 galactosylated N-glycans of ACE2 were pivotal for the bindings of SARS-CoV-2 with ACE2. Furthermore, we found that the glycoproteins isolated from bovine milk contained abundant galactosylated glycans, which were similar to the glycoforms of ACE2, and could prevent the entry of SARS-CoV-2 pseudovirus. Our study provided the evidences that the β1-4 galactosylated N-glycans on ACE2 were key glycan receptors of SARS-CoV-2, and valuable strategies for developing an inexpensive protein drug to prevent SARS-CoV-2 infection.