Structural highlights
Function
[Q91IJ0_9INFA] Binds to sialic acid-containing receptors on the cell surface, bringing about the attachment of the virus particle to the cell. This attachment induces virion internalization of about two third of the virus particles through clathrin-dependent endocytosis and about one third through a clathrin- and caveolin-independent pathway. Plays a major role in the determination of host range restriction and virulence. Class I viral fusion protein. Responsible for penetration of the virus into the cell cytoplasm by mediating the fusion of the membrane of the endocytosed virus particle with the endosomal membrane. Low pH in endosomes induces an irreversible conformational change in HA2, releasing the fusion hydrophobic peptide. Several trimers are required to form a competent fusion pore (By similarity).[RuleBase:RU003324][SAAS:SAAS013829_004_327643]
Publication Abstract from PubMed
The highly conserved first 23 residues of the influenza hemagglutinin HA2 subunit constitute the fusion domain, which plays a pivotal role in fusing viral and host-cell membranes. At neutral pH, this peptide adopts a tight helical hairpin wedge structure, stabilized by aliphatic hydrogen bonding and charge-dipole interactions. We demonstrate that at low pH, where the fusion process is triggered, the native peptide transiently visits activated states that are very similar to those sampled by a G8A mutant. This mutant retains a small fraction of helical hairpin conformation, in rapid equilibrium with at least two open structures. The exchange rate between the closed and open conformations of the wild-type fusion peptide is approximately 40 kHz, with a total open-state population of approximately 20%. Transitions to these activated states are likely to play a crucial role in formation of the fusion pore, an essential structure required in the final stage of membrane fusion.
pH-triggered, activated-state conformations of the influenza hemagglutinin fusion peptide revealed by NMR.,Lorieau JL, Louis JM, Schwieters CD, Bax A Proc Natl Acad Sci U S A. 2012 Nov 19. PMID:23169643[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Lorieau JL, Louis JM, Schwieters CD, Bax A. pH-triggered, activated-state conformations of the influenza hemagglutinin fusion peptide revealed by NMR. Proc Natl Acad Sci U S A. 2012 Nov 19. PMID:23169643 doi:http://dx.doi.org/10.1073/pnas.1213801109
