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Enhanced stability of the SARS CoV-2 spike glycoprotein following modification of an alanine cavity in the protein core.
- Source :
- PLoS Pathogens, Vol 19, Iss 5, p e1010981 (2023)
- Publication Year :
- 2023
- Publisher :
- Public Library of Science (PLoS), 2023.
-
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.
- Subjects :
- Immunologic diseases. Allergy
RC581-607
Biology (General)
QH301-705.5
Subjects
Details
- Language :
- English
- ISSN :
- 15537366 and 15537374
- Volume :
- 19
- Issue :
- 5
- Database :
- Directory of Open Access Journals
- Journal :
- PLoS Pathogens
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.6d3cf0974e2e42daa96111a1d687d350
- Document Type :
- article
- Full Text :
- https://doi.org/10.1371/journal.ppat.1010981