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Structural definition of a unique neutralization epitope on the receptor-binding domain of MERS-CoV spike glycoprotein
Structural highlights
FunctionSPIKE_MERS1 Attaches the virion to the cell membrane by interacting with host receptor, initiating the infection (By similarity). Interacts with host DPP4 to mediate virla entry.[HAMAP-Rule:MF_04099][1] 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 major mechanism of antibody-mediated neutralization of the Middle East respiratory syndrome coronavirus (MERS-CoV) involves competition with the cellular receptor dipeptidyl peptidase 4 (DPP4) for binding to the receptor-binding domain (RBD) of the spike (S) glycoprotein. Here, we report a unique epitope and unusual neutralizing mechanism of the isolated human antibody MERS-4. Structurally, MERS-4 approached the RBD from the outside of the RBD-DPP4 binding interface. Such binding resulted in the folding of the beta5-beta6 loop toward a shallow groove on the RBD interface critical for accommodating DPP4. The key residues for binding are identified through site-directed mutagenesis. Structural modeling revealed that MERS-4 binds to RBD only in the "up" position in the S trimer. Furthermore, MERS-4 demonstrated synergy with several reported antibodies. These results indicate that MERS-4 neutralizes MERS-CoV by indirect rather than direct competition with DPP4. This mechanism provides a valuable addition for the combined use of antibodies against MERS-CoV infection. Structural Definition of a Unique Neutralization Epitope on the Receptor-Binding Domain of MERS-CoV Spike Glycoprotein.,Zhang S, Zhou P, Wang P, Li Y, Jiang L, Jia W, Wang H, Fan A, Wang D, Shi X, Fang X, Hammel M, Wang S, Wang X, Zhang L Cell Rep. 2018 Jul 10;24(2):441-452. doi: 10.1016/j.celrep.2018.06.041. PMID:29996104[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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