7y1y
S-ECD (Omicron BA.2) in complex with PD of ACE2S-ECD (Omicron BA.2) in complex with PD of ACE2
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 Omicron variants of SARS-CoV-2 have emerged as the dominant strains worldwide, causing the COVID-19 pandemic. Each Omicron subvariant contains at least 30 mutations on the spike protein (S protein) compared to the original wild-type (WT) strain. Here we report the cryo-EM structures of the trimeric S proteins from the BA.1, BA.2, BA.3, and BA.4/BA.5 subvariants, with BA.4 and BA.5 sharing the same S protein mutations, each in complex with the surface receptor ACE2. All three receptor-binding domains of the S protein from BA.2 and BA.4/BA.5 are "up", while the BA.1 S protein has two "up" and one "down". The BA.3 S protein displays increased heterogeneity, with the majority in the all "up" RBD state. The different conformations preferences of the S protein are consistent with their varied transmissibility. By analyzing the position of the glycan modification on Asn343, which is located at the S309 epitopes, we have uncovered the underlying immune evasion mechanism of the Omicron subvariants. Our findings provide a molecular basis of high infectivity and immune evasion of Omicron subvariants, thereby offering insights into potential therapeutic interventions against SARS-CoV-2 variants. Structural Basis for the Enhanced Infectivity and Immune Evasion of Omicron Subvariants.,Li Y, Shen Y, Zhang Y, Yan R Viruses. 2023 Jun 20;15(6):1398. doi: 10.3390/v15061398. PMID:37376697[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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