9kzz
From Proteopedia
Structure of SARS-CoV-2 EG.5.1 Variant Spike protein complexed with antibody XGi-171
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 PubMedThe receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) protein continues to evolve, facilitating antibody evasion. It remains unclear whether any conserved RBD epitopes persist across SARS-CoV-2 variants and whether vaccination and/or breakthrough infection (BTI) can elicit antibodies capable of targeting these conserved regions to counter future variants. Here, using a heterogeneous double-bait single B-cell sorting strategy, we identify a subset of antibodies with broad-spectrum RBD binding, including recognition of SARS-CoV-1 and emerging variants such as EG.5.1, BA.2.86, JN.1, and KP.2/3. These broadly binding antibodies (bbAbs) exhibit elevated levels of somatic hypermutation but are infrequently derived from clonally expanded B lymphocytes. Passive transfer of representative bbAbs reduces viral infection in a male hamster model. Structural analyses reveals that these bbAbs primarily target three distinct, highly conserved RBD epitopes, suggesting potential regions of future mutational pressure and highlighting the presence of conserved and immunogenic RBD conformations that may serve as a foundation for the development of broadly protective vaccines. Orphan broadly RBD-binding antibodies annotate three remaining conserved RBD epitopes along SARS-CoV-2 evolution.,Xie M, Qiu Y, Zhao X, Shi J, Liu Y, Zhang Q, He J, Li J, Liu L, Sun S, Zhu Y, Mao Q, Long Y, Oliveira TY, Wang Z, Zhou Y, Yan Y, Xia A, Zai W, Mayer CT, Xie Y, Jiang S, Lu L, Xia R, Wu F, Sun L, Wang P, Chu H, Wang Q Nat Commun. 2025 Nov 26;16(1):10566. doi: 10.1038/s41467-025-65596-0. PMID:41298374[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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