5thf
From Proteopedia
Crystal structure of H3 hemagglutinin with insertion of two amino acids in the 150-loop from the A/Hong Kong/1/1968 (H3N2) influenza virus
Structural highlights
FunctionHEMA_I68A4 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). Publication Abstract from PubMedAdaptation of influenza A viruses to new hosts are rare events but are the basis for emergence of new influenza pandemics in the human population. Thus, understanding the processes involved in such events is critical for anticipating potential pandemic threats. In 2013, the first case of human infection by an avian H10N8 virus was reported, yet the H10 hemagglutinin (HA) maintains avian receptor specificity. However, the 150-loop of H10 HA, as well as related H7 and H15 subtypes, contains a two-residue insert that can potentially block human receptor binding. Mutation of the 150-loop on the background of Q226L and G228S mutations, which arose in the receptor-binding site of human pandemic H2 and H3 viruses, resulted in acquisition of human-type receptor specificity. Crystal structures of H10 HA mutants with human and avian receptor analogs, receptor-binding studies, and tissue staining experiments illustrate the important role of the 150-loop in H10 receptor specificity. The 150-Loop Restricts the Host Specificity of Human H10N8 Influenza Virus.,Tzarum N, de Vries RP, Peng W, Thompson AJ, Bouwman KM, McBride R, Yu W, Zhu X, Verheije MH, Paulson JC, Wilson IA Cell Rep. 2017 Apr 11;19(2):235-245. doi: 10.1016/j.celrep.2017.03.054. PMID:28402848[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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