9wsp
Cryo-EM structure of SARS CoV2 S protein with stabilising mutations
Structural highlights
FunctionSPIKE_SARS2 attaches the virion to the cell membrane by interacting with host receptor, initiating the infection (By similarity). Binding to human ACE2 receptor and internalization of the virus into the endosomes of the host cell induces conformational changes in the Spike glycoprotein (PubMed:32142651, PubMed:32075877, PubMed:32155444). Uses also human TMPRSS2 for priming in human lung cells which is an essential step for viral entry (PubMed:32142651). Proteolysis by cathepsin CTSL may unmask the fusion peptide of S2 and activate membranes fusion within endosomes.[HAMAP-Rule:MF_04099][1] [2] [3] mediates fusion of the virion and cellular membranes by acting as a class I viral fusion protein. Under the current model, the protein has at least three conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and target cell membrane fusion, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes.[HAMAP-Rule:MF_04099] Acts as a viral fusion peptide which is unmasked following S2 cleavage occurring upon virus endocytosis.[HAMAP-Rule:MF_04099] Publication Abstract from PubMedZoonotic spillover of sarbecoviruses to humans resulted in the SARS-CoV-1 outbreak in 2003 and the current COVID-19 pandemic caused by SARS-CoV-2. In both cases, the viral spike protein (S) is the principal target of neutralizing antibodies that prevent infection. Within the spike, the immunodominant receptor-binding domain (RBD) is the primary target of neutralizing antibodies in COVID-19 convalescent sera and vaccine recipients. We have constructed stabilized RBD derivatives of different sarbecoviruses: SARS-CoV-1 (Clade 1a), WIV-1 (Clade 1a), RaTG13 (Clade 1b), RmYN02 (Clade 2), and BtKY72 (Clade 3). Stabilization enhanced yield by 3-23-fold. The RBD derivatives were conformationally intact, as assayed by binding to multiple broadly neutralizing antibodies. The stabilized RBDs show significant enhancement in apparent T(m), exhibit resistance to a 2-h incubation at temperatures up to 60 degrees C in PBS in contrast to the corresponding WT RBDs, and show prolonged stability of over 15 days at 37 degrees C after lyophilization. In mice immunizations, both stabilization and trimerization significantly enhanced elicited neutralization titers by approximately 100-fold. The stabilized RBD cocktail elicited highly neutralizing titers against both homologous and heterologous pseudoviruses. The immunogenicity of the vaccine formulation was assessed in both naive and SARS-CoV-2 preimmunized mice, revealing an absence of immune imprinting, thus indicating its suitability for use in future sarbecovirus-origin epidemics or pandemics. Development of a Thermostable and Broadly Neutralizing Pan-Sarbecovirus Vaccine Candidate.,Srivastava S, Kumar S, Mishra S, Rajmani RS, Singh R, Dutta S, Ringe RP, Varadarajan R ACS Infect Dis. 2026 Jan 9;12(1):104-118. doi: 10.1021/acsinfecdis.5c00479. Epub , 2025 Dec 23. PMID:41436061[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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