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.

阐明糖基化（glycosylation）在严重急性呼吸综合征冠状病毒2（SARS-CoV-2）刺突（S）蛋白与血管紧张素转换酶2（ACE2）相互作用中的精准作用，对于解析SARS-CoV-2感染的分子机制具有重要意义。本研究采用抗体覆盖型凝集素微阵列、分子对接分析及糖苷酶消化实验，探究了SARS-CoV-2 S1亚基与ACE2表面N-聚糖（N-glycans）的功能。研究结果显示，S蛋白与ACE2表面均以半乳糖基化聚糖（galactosylated glycans）为主。尤为关键的是，本研究证实ACE2的β1-4半乳糖基化N-聚糖是SARS-CoV-2与ACE2结合的关键位点。此外，本研究发现从牛乳中分离得到的糖蛋白富含半乳糖基化聚糖，其糖型与ACE2的糖型相似，且可阻断SARS-CoV-2假病毒（pseudovirus）的入侵。本研究提供了证据表明，ACE2表面的β1-4半乳糖基化N-聚糖是SARS-CoV-2的关键聚糖受体，同时为开发低成本抗SARS-CoV-2感染蛋白药物提供了极具价值的策略。