8h15

Structural highlights

Function

SPIKE_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]

References

1. ↑ Wang SM, Huang KJ, Wang CT. Severe acute respiratory syndrome coronavirus spike protein counteracts BST2-mediated restriction of virus-like particle release. J Med Virol. 2019 Oct;91(10):1743-1750. doi: 10.1002/jmv.25518. Epub 2019 Jul 10. PMID:31199522 doi:http://dx.doi.org/10.1002/jmv.25518
2. ↑ Wong SK, Li W, Moore MJ, Choe H, Farzan M. A 193-amino acid fragment of the SARS coronavirus S protein efficiently binds angiotensin-converting enzyme 2. J Biol Chem. 2004 Jan 30;279(5):3197-201. Epub 2003 Dec 11. PMID:14670965 doi:http://dx.doi.org/10.1074/jbc.C300520200
3. ↑ Jeffers SA, Tusell SM, Gillim-Ross L, Hemmila EM, Achenbach JE, Babcock GJ, Thomas WD Jr, Thackray LB, Young MD, Mason RJ, Ambrosino DM, Wentworth DE, Demartini JC, Holmes KV. CD209L (L-SIGN) is a receptor for severe acute respiratory syndrome coronavirus. Proc Natl Acad Sci U S A. 2004 Nov 2;101(44):15748-53. doi:, 10.1073/pnas.0403812101. Epub 2004 Oct 20. PMID:15496474 doi:http://dx.doi.org/10.1073/pnas.0403812101
4. ↑ Belouzard S, Chu VC, Whittaker GR. Activation of the SARS coronavirus spike protein via sequential proteolytic cleavage at two distinct sites. Proc Natl Acad Sci U S A. 2009 Apr 7;106(14):5871-6. doi:, 10.1073/pnas.0809524106. Epub 2009 Mar 24. PMID:19321428 doi:http://dx.doi.org/10.1073/pnas.0809524106