4kqz
From Proteopedia
structure of the receptor binding domain (RBD) of MERS-CoV spike
Structural highlights
FunctionK0BRG7_MERS 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 PubMedThe newly emergent Middle East respiratory syndrome coronavirus (MERS-CoV) can cause severe pulmonary disease in humans, representing the second example of a highly pathogenic coronavirus, the first being SARS-CoV. CD26 (also known as dipeptidyl peptidase 4, DPP4) was recently identified as the cellular receptor for MERS-CoV. The engagement of the MERS-CoV spike protein with CD26 mediates viral attachment to host cells and virus-cell fusion, thereby initiating infection. Here we delineate the molecular basis of this specific interaction by presenting the first crystal structures of both the free receptor binding domain (RBD) of the MERS-CoV spike protein and its complex with CD26. Furthermore, binding between the RBD and CD26 is measured using real-time surface plasmon resonance with a dissociation constant of 16.7 nM. The viral RBD is composed of a core subdomain homologous to that of the SARS-CoV spike protein, and a unique strand-dominated external receptor binding motif that recognizes blades IV and V of the CD26 beta-propeller. The atomic details at the interface between the two binding entities reveal a surprising protein-protein contact mediated mainly by hydrophilic residues. Sequence alignment indicates, among betacoronaviruses, a possible structural conservation for the region homologous to the MERS-CoV RBD core, but a high variation in the external receptor binding motif region for virus-specific pathogenesis such as receptor recognition. Molecular basis of binding between novel human coronavirus MERS-CoV and its receptor CD26.,Lu G, Hu Y, Wang Q, Qi J, Gao F, Li Y, Zhang Y, Zhang W, Yuan Y, Bao J, Zhang B, Shi Y, Yan J, Gao GF Nature. 2013 Aug 8;500(7461):227-31. doi: 10.1038/nature12328. Epub 2013 Jul 7. PMID:23831647[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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