6n5a
From Proteopedia
Crystal structure of an equine H7 hemagglutinin from A/equine/NY/49/73 (H7N7)
Structural highlights
Function[A0A348FV55_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 either through clathrin-dependent endocytosis or through 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.[HAMAP-Rule:MF_04072][SAAS:SAAS01039073] 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.[RuleBase:RU003324] Publication Abstract from PubMedA species barrier for the influenza A virus is the differential expression of sialic acid, which can either be alpha2,3-linked for avians or alpha2,6-linked for human viruses. The influenza A virus hosts also express other species-specific sialic acid derivatives. One major modification at C-5 is N-glycolyl (NeuGc), instead of N-acetyl (NeuAc). N-glycolyl is mammalian specific and expressed in pigs and horses, but not in humans, ferrets, seals, or dogs. Hemagglutinin (HA) adaptation to either N-acetyl or N-glycolyl is analyzed on a sialoside microarray containing both alpha2,3- and alpha2,6-linkage modifications on biologically relevant N-glycans. Binding studies reveal that avian, human, and equine HAs bind either N-glycolyl or N-acetyl. Structural data on N-glycolyl binding HA proteins of both H5 and H7 origin describe this specificity. Neuraminidases can cleave N-glycolyl efficiently, and tissue-binding studies reveal strict species specificity. The exclusive manner in which influenza A viruses differentiate between N-glycolyl and N-acetyl is indicative of selection. N-Glycolylneuraminic Acid as a Receptor for Influenza A Viruses.,Broszeit F, Tzarum N, Zhu X, Nemanichvili N, Eggink D, Leenders T, Li Z, Liu L, Wolfert MA, Papanikolaou A, Martinez-Romero C, Gagarinov IA, Yu W, Garcia-Sastre A, Wennekes T, Okamatsu M, Verheije MH, Wilson IA, Boons GJ, de Vries RP Cell Rep. 2019 Jun 11;27(11):3284-3294.e6. doi: 10.1016/j.celrep.2019.05.048. PMID:31189111[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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