9lyp
Alpha SARS-CoV-2 spike protein RBD-down in complex with REGN10987 Fab homologue (local refinement)
Structural highlights
FunctionA0A8A3HA81_SARS2 Spike protein S1: attaches the virion to the cell membrane by interacting with host receptor, initiating the infection.[HAMAP-Rule:MF_04099] Spike protein S2': Acts as a viral fusion peptide which is unmasked following S2 cleavage occurring upon virus endocytosis.[HAMAP-Rule:MF_04099] Spike protein S2: 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] Publication Abstract from PubMedOne of the approaches for treatment of COVID-19 is a use of neutralizing antibodies (nAbs). The study of the mechanisms by which nAbs recognize different strains of SARS-CoV-2 may facilitate the development of new drugs and vaccines against the coronavirus infection. In this work, we present the 3.1 A resolution cryo-electron microscopy structure of a full-length trimeric spike-protein (S-protein) of the SARS-CoV-2 Alpha (B.1.1.7) variant in complex with the Fab of the REGN10987 nAb. In the complex, two receptor-binding domains (RBDs) of the S-protein were observed in the 'up' state, whereas third RBD was in the 'down' state. This distinguishes the obtained structure from the complex of Delta (B.1.617.2) S-protein with REGN10987-Fab, where only one RBD was in the 'up' state. Probably some of the substituted residues (K478T, A570D, and S982A) located at the interprotomer interfaces are responsible for the greater Alpha S-protein opening upon the REGN10987-Fab binding. The Fab identically binds to the RBD in the both 'up' and 'down' conformations. The RBD-Fab interaction interface was refined to a resolution of 3.6 A. The antibody binds to the receptor-binding motif (RBM), which prevents the S-protein from the binding to its receptor, angiotensin-converting enzyme 2 (ACE-2). Comparison with the structures of the Wuhan (wild type) and Delta RBD variants in complex with REGN10987-Fab revealed that the N501Y and T478K/L452R mutations presented in the RBM of the Alpha and Delta variants, respectively, do not affect the mode of the RBD-Fab interaction. Structure and dynamics of Alpha B.1.1.7 SARS-CoV-2 S-protein in complex with Fab of neutralizing antibody REGN10987.,Kocharovskaya MV, Pichkur EB, Ivannikov AD, Kharlampieva DD, Grafskaia EN, Lyukmanova EN, Kirpichnikov MP, Shenkarev ZO Biochem Biophys Res Commun. 2025 Apr 1;755:151558. doi: , 10.1016/j.bbrc.2025.151558. Epub 2025 Feb 27. PMID:40043614[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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