2ghw
Crystal structure of SARS spike protein receptor binding domain in complex with a neutralizing antibody, 80R
Structural highlights
FunctionSPIKE_SARS May down-regulate host tetherin (BST2) by lysosomal degradation, thereby counteracting its antiviral activity.[1] Attaches the virion to the cell membrane by interacting with host receptor, initiating the infection (By similarity). Binding to human ACE2 and CLEC4M/DC-SIGNR receptors and internalization of the virus into the endosomes of the host cell induces conformational changes in the S glycoprotein. Proteolysis by cathepsin CTSL may unmask the fusion peptide of S2 and activate membrane fusion within endosomes.[HAMAP-Rule:MF_04099][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][4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSevere acute respiratory syndrome (SARS) is a newly emerged infectious disease that caused pandemic spread in 2003. The etiological agent of SARS is a novel coronavirus (SARS-CoV). The coronaviral surface spike protein S is a type I transmembrane glycoprotein that mediates initial host binding via the cell surface receptor angiotensin-converting enzyme 2 (ACE2), as well as the subsequent membrane fusion events required for cell entry. Here we report the crystal structure of the S1 receptor binding domain (RBD) in complex with a neutralizing antibody, 80R, at 2.3 A resolution, as well as the structure of the uncomplexed S1 RBD at 2.2 A resolution. We show that the 80R-binding epitope on the S1 RBD overlaps very closely with the ACE2-binding site, providing a rationale for the strong binding and broad neutralizing ability of the antibody. We provide a structural basis for the differential effects of certain mutations in the spike protein on 80R versus ACE2 binding, including escape mutants, which should facilitate the design of immunotherapeutics to treat a future SARS outbreak. We further show that the RBD of S1 forms dimers via an extensive interface that is disrupted in receptor- and antibody-bound crystal structures, and we propose a role for the dimer in virus stability and infectivity. Structural basis of neutralization by a human anti-severe acute respiratory syndrome spike protein antibody, 80R.,Hwang WC, Lin Y, Santelli E, Sui J, Jaroszewski L, Stec B, Farzan M, Marasco WA, Liddington RC J Biol Chem. 2006 Nov 10;281(45):34610-6. Epub 2006 Sep 5. PMID:16954221[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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