Structural highlights
Function
[SPIKE_CVHSA] S1 attaches the virion to the cell membrane by interacting with human ACE2 and CLEC4M/DC-SIGNR, initiating the infection. Binding to the receptor and internalization of the virus into the endosomes of the host cell probably induces conformational changes in the S glycoprotein. Proteolysis by cathepsin CTSL may unmask the fusion peptide of S2 and activate membranes fusion within endosomes. S2 is 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.
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 PubMed
A coronavirus (CoV) has recently been identified as the causative agent of the severe acute respiratory syndrome (SARS) in humans. CoVs enter target cells through fusion of viral and cellular membranes mediated by the viral envelope glycoprotein S. We have determined by x-ray crystallography the structure of a proteolytically stable core fragment from the heptad repeat (HR) regions HR1 and HR2 of the SARS-CoV S protein. We have also determined the structure of an HR1-HR2 S core fragment, containing a shorter HR1 peptide and a C-terminally longer HR2 peptide that extends up to the transmembrane region. In these structures, three HR1 helices form a parallel coiled-coil trimer, whereas three HR2 peptides pack in an oblique and antiparallel fashion into the coiled-coil hydrophobic grooves, adopting mixed extended and alpha-helical conformations as in postfusion paramyxoviruses F proteins structures. Our structure positions a previously proposed internal fusion peptide adjacent to the N-terminus of HR1. Peptides from the HR2 region of SARS-CoV S have been shown to inhibit viral entry and infection in vitro. The structures presented here can thus open the path to the design of small-molecule inhibitors of viral entry and candidate vaccine antigens against this virus.
Structure of a proteolytically resistant core from the severe acute respiratory syndrome coronavirus S2 fusion protein.,Supekar VM, Bruckmann C, Ingallinella P, Bianchi E, Pessi A, Carfi A Proc Natl Acad Sci U S A. 2004 Dec 28;101(52):17958-63. Epub 2004 Dec 16. PMID:15604146[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Supekar VM, Bruckmann C, Ingallinella P, Bianchi E, Pessi A, Carfi A. Structure of a proteolytically resistant core from the severe acute respiratory syndrome coronavirus S2 fusion protein. Proc Natl Acad Sci U S A. 2004 Dec 28;101(52):17958-63. Epub 2004 Dec 16. PMID:15604146
