Article ; Online: Enhanced stability of the SARS CoV-2 spike glycoprotein following modification of an alanine cavity in the protein core.
2023 Volume 19, Issue 5, Page(s) e1010981
Abstract: The spike (S) glycoprotein of SARS CoV-2 is the target of neutralizing antibodies (NAbs) that are crucial for vaccine effectiveness. The S1 subunit binds ACE2 while the S2 subunit mediates virus-cell membrane fusion. S2 is a class I fusion glycoprotein ... ...
| Abstract | The spike (S) glycoprotein of SARS CoV-2 is the target of neutralizing antibodies (NAbs) that are crucial for vaccine effectiveness. The S1 subunit binds ACE2 while the S2 subunit mediates virus-cell membrane fusion. S2 is a class I fusion glycoprotein subunit and contains a central coiled coil that acts as a scaffold for the conformational changes associated with fusion function. The coiled coil of S2 is unusual in that the 3-4 repeat of inward-facing positions are mostly occupied by polar residues that mediate few inter-helical contacts in the prefusion trimer. We examined how insertion of bulkier hydrophobic residues (Val, Leu, Ile, Phe) to fill a cavity next to Ala1016 and Ala1020 in the 3-4 repeat affects the stability and antigenicity of S trimers. Substitution of Ala1016 with bulkier hydrophobic residues in the context of a prefusion-stabilized S trimer, S2P-FHA, was associated with increased thermal stability. S glycoprotein membrane fusion function was retained with Ala1016/Ala1020 cavity-filling mutations associated with improved recombinant S2P-FHA thermostability, however 2 mutants, A1016L and A1016V/A1020I, lacked ability to mediate entry of S-HIV-1 pseudoparticles into 293-ACE2 cells. When assessed as immunogens, two thermostable S2P-FHA mutants derived from the ancestral isolate, A1016L (16L) and A1016V/A1020I (VI) elicited neutralizing antibody with 50%-inhibitory dilutions (ID50s) in the range 2,700-5,110 for ancestral and Delta-derived viruses, and 210-1,744 for Omicron BA.1. The antigens elicited antibody specificities directed to the receptor-binding domain (RBD), N-terminal domain (NTD), fusion peptide and stem region of S2. The VI mutation enabled the production of intrinsically stable Omicron BA.1 and Omicron BA.4/5 S2P-FHA-like ectodomain oligomers in the absence of an external trimerization motif (T4 foldon), thus representing an alternative approach for stabilizing oligomeric S glycoprotein vaccines. |
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| MeSH term(s) | Humans ; Spike Glycoprotein, Coronavirus ; Severe Acute Respiratory Syndrome ; Angiotensin-Converting Enzyme 2 ; COVID-19 ; Antibodies, Neutralizing |
| Chemical Substances | spike protein, SARS-CoV-2 ; Spike Glycoprotein, Coronavirus ; Angiotensin-Converting Enzyme 2 (EC 3.4.17.23) ; Antibodies, Neutralizing |
| Language | English |
| Publishing date | 2023-05-18 |
| Publishing country | United States |
| Document type | Journal Article ; Research Support, Non-U.S. Gov't |
| ZDB-ID | 2205412-1 |
| ISSN | 1553-7374 ; 1553-7374 |
| ISSN (online) | 1553-7374 |
| ISSN | 1553-7374 |
| DOI | 10.1371/journal.ppat.1010981 |
| Database | MEDical Literature Analysis and Retrieval System OnLINE |
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