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Crystal structure of SARS-CoV-2 spike stem helix peptide in complex with neutralizing antibody COV93-03
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 PubMedHumanity has faced three recent outbreaks of novel betacoronaviruses, emphasizing the need to develop approaches that broadly target coronaviruses. Here, we identify 55 monoclonal antibodies from COVID-19 convalescent donors that bind diverse betacoronavirus spike proteins. Most antibodies targeted an S2 epitope that included the K814 residue and were non-neutralizing. However, 11 antibodies targeting the stem helix neutralized betacoronaviruses from different lineages. Eight antibodies in this group, including the six broadest and most potent neutralizers, were encoded by IGHV1-46 and IGKV3-20. Crystal structures of three antibodies of this class at 1.5-1.75-A resolution revealed a conserved mode of binding. COV89-22 neutralized SARS-CoV-2 variants of concern including Omicron BA.4/5 and limited disease in Syrian hamsters. Collectively, these findings identify a class of IGHV1-46/IGKV3-20 antibodies that broadly neutralize betacoronaviruses by targeting the stem helix but indicate these antibodies constitute a small fraction of the broadly reactive antibody response to betacoronaviruses after SARS-CoV-2 infection. Rare, convergent antibodies targeting the stem helix broadly neutralize diverse betacoronaviruses.,Dacon C, Peng L, Lin TH, Tucker C, Lee CD, Cong Y, Wang L, Purser L, Cooper AJR, Williams JK, Pyo CW, Yuan M, Kosik I, Hu Z, Zhao M, Mohan D, Peterson M, Skinner J, Dixit S, Kollins E, Huzella L, Perry D, Byrum R, Lembirik S, Murphy M, Zhang Y, Yang ES, Chen M, Leung K, Weinberg RS, Pegu A, Geraghty DE, Davidson E, Doranz BJ, Douagi I, Moir S, Yewdell JW, Schmaljohn C, Crompton PD, Mascola JR, Holbrook MR, Nemazee D, Wilson IA, Tan J Cell Host Microbe. 2023 Jan 11;31(1):97-111.e12. doi: 10.1016/j.chom.2022.10.010. , Epub 2022 Nov 7. PMID:36347257[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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