5k6b

Structural highlights

Function

[FUS_HRSVA] Class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and plasma cell membrane fusion, the heptad repeat (HR) regions 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 plasma cell membranes. Directs fusion of viral and cellular membranes leading to delivery of the nucleocapsid into the cytoplasm. This fusion is pH independent and occurs directly at the outer cell membrane. The trimer of F1-F2 (protein F) interacts with glycoprotein G at the virion surface. Upon binding of G to heparan sulfate, the hydrophobic fusion peptide is unmasked and interacts with the cellular membrane, inducing the fusion between host cell and virion membranes. Notably, RSV fusion protein is able to interact directly with heparan sulfate and therefore actively participates in virus attachment. Furthermore, the F2 subunit was identifed as the major determinant of RSV host cell specificity. Later in infection, proteins F expressed at the plasma membrane of infected cells mediate fusion with adjacent cells to form syncytia, a cytopathic effect that could lead to tissue necrosis. The fusion protein is also able to trigger p53-dependent apoptosis.^{[1] [2]}

References

1. ↑ Schlender J, Zimmer G, Herrler G, Conzelmann KK. Respiratory syncytial virus (RSV) fusion protein subunit F2, not attachment protein G, determines the specificity of RSV infection. J Virol. 2003 Apr;77(8):4609-16. PMID:12663767
2. ↑ Eckardt-Michel J, Lorek M, Baxmann D, Grunwald T, Keil GM, Zimmer G. The fusion protein of respiratory syncytial virus triggers p53-dependent apoptosis. J Virol. 2008 Apr;82(7):3236-49. Epub 2008 Jan 23. PMID:18216092 doi:JVI.01887-07
3. ↑ Joyce MG, Zhang B, Ou L, Chen M, Chuang GY, Druz A, Kong WP, Lai YT, Rundlet EJ, Tsybovsky Y, Yang Y, Georgiev IS, Guttman M, Lees CR, Pancera M, Sastry M, Soto C, Stewart-Jones GB, Thomas PV, Van Galen JG, Baxa U, Lee KK, Mascola JR, Graham BS, Kwong PD. Iterative structure-based improvement of a fusion-glycoprotein vaccine against RSV. Nat Struct Mol Biol. 2016 Aug 1. doi: 10.1038/nsmb.3267. PMID:27478931 doi:http://dx.doi.org/10.1038/nsmb.3267