{"doi":"10.1371/journal.ppat.1010981","title":"Enhanced stability of the SARS CoV-2 spike glycoprotein following modification of an alanine cavity in the protein core","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.","journal":"PLoS Pathogens","year":2023,"id":363955,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":7,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9613,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":349356,"name":"Christine Langer","orcid":null,"position":1,"is_corresponding":false},{"id":807125,"name":"Irene Boo","orcid":"0000-0003-0923-0972","position":2,"is_corresponding":false},{"id":1011228,"name":"Tasnim Zakir","orcid":null,"position":3,"is_corresponding":false},{"id":1010773,"name":"Anouschka Akerman","orcid":"0000-0002-4045-2189","position":4,"is_corresponding":false},{"id":1010774,"name":"Vanessa Milogiannakis","orcid":"0000-0003-2023-2303","position":5,"is_corresponding":false},{"id":566009,"name":"Anupriya Aggarwal","orcid":"0000-0001-8678-0519","position":6,"is_corresponding":false},{"id":484481,"name":"Bronte A. Johnstone","orcid":"0000-0003-3313-5553","position":7,"is_corresponding":false},{"id":1118352,"name":"Jungmin Ha","orcid":"0000-0003-4088-3736","position":8,"is_corresponding":false},{"id":816471,"name":"Fasséli Coulibaly","orcid":"0000-0003-3380-2117","position":9,"is_corresponding":false},{"id":566015,"name":"Stuart Turville","orcid":"0000-0003-1918-5343","position":10,"is_corresponding":false},{"id":347539,"name":"Heidi E. Drummer","orcid":"0000-0002-0042-6277","position":11,"is_corresponding":false},{"id":347538,"name":"Pantelis Poumbourios","orcid":"0000-0002-2772-1962","position":0,"is_corresponding":true}],"reference_count":87,"raw_metadata":null,"created_at":"2026-07-19T01:14:32.510714Z","pmid":"37200378","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}