Article ; Online: Stabilization of the Metastable Pre-Fusion Conformation of the SARS-CoV-2 Spike Glycoprotein through N-Linked Glycosylation of the S2 Subunit.
2024 Volume 16, Issue 2
Abstract: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic, represents a serious threat to public health. The spike (S) glycoprotein of SARS-CoV-2 mediates viral ... ...
| Abstract | Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic, represents a serious threat to public health. The spike (S) glycoprotein of SARS-CoV-2 mediates viral entry into host cells and is heavily glycosylated. In this study, we systemically analyzed the roles of 22 putative N-linked glycans in SARS-CoV-2 S protein expression, membrane fusion, viral entry, and stability. Using the α-glycosidase inhibitors castanospermine and NB-DNJ, we confirmed that disruption of N-linked glycosylation blocked the maturation of the S protein, leading to the impairment of S protein-mediated membrane fusion. Single-amino-acid substitution of each of the 22 N-linked glycosylation sites with glutamine revealed that 9 out of the 22 N-linked glycosylation sites were critical for S protein folding and maturation. Thus, substitution at these sites resulted in reduced S protein-mediated cell-cell fusion and viral entry. Notably, the N1074Q mutation markedly affected S protein stability and induced significant receptor-independent syncytium (RIS) formation in HEK293T/hACE2-KO cells. Additionally, the removal of the furin cleavage site partially compensated for the instability induced by the N1074Q mutation. Although the corresponding mutation in the SARS-CoV S protein (N1056Q) did not induce RIS in HEK293T cells, the N669Q and N1080Q mutants exhibited increased fusogenic activity and did induce syncytium formation in HEK293T cells. Therefore, N-glycans on the SARS-CoV and SARS-CoV-2 S2 subunits are highly important for maintaining the pre-fusion state of the S protein. This study revealed the critical roles of N-glycans in S protein maturation and stability, information that has implications for the design of vaccines and antiviral strategies. |
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| MeSH term(s) | Humans ; SARS-CoV-2/genetics ; SARS-CoV-2/metabolism ; COVID-19 ; Spike Glycoprotein, Coronavirus/metabolism ; Glycosylation ; HEK293 Cells ; Severe acute respiratory syndrome-related coronavirus ; Polysaccharides/metabolism ; Virus Internalization |
| Chemical Substances | spike protein, SARS-CoV-2 ; Spike Glycoprotein, Coronavirus ; Polysaccharides |
| Language | English |
| Publishing date | 2024-01-31 |
| Publishing country | Switzerland |
| Document type | Journal Article |
| ZDB-ID | 2516098-9 |
| ISSN | 1999-4915 ; 1999-4915 |
| ISSN (online) | 1999-4915 |
| ISSN | 1999-4915 |
| DOI | 10.3390/v16020223 |
| Database | MEDical Literature Analysis and Retrieval System OnLINE |
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