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6bkm

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Crystal structure of the A/Hong Kong/1/1968 (H3N2) influenza virus hemagglutinin E190D mutant apo form

Structural highlights

6bkm is a 6 chain structure with sequence from Influenza A virus (A/Hong Kong/1/1968(H3N2)) and Influenza A virus (A/nt/60/1968(H3N2)). Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.2Å
Ligands:	, , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

HEMA_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 PubMed

The hemagglutinin (HA) receptor-binding site (RBS) in human influenza A viruses is critical for attachment to host cells, which imposes a functional constraint on its natural evolution. On the other hand, being part of the major antigenic sites, the HA RBS of human H3N2 viruses needs to constantly mutate to evade the immune system. From large-scale mutagenesis experiments, we here show that several of the natural RBS substitutions become integrated into an extensive epistatic network that prevents substitution reversion. X-ray structural analysis reveals the mechanistic consequences as well as changes in the mode of receptor binding. Further studies are necessary to elucidate whether such entrenchment limits future options for immune escape or adversely affect long-term viral fitness.

A complex epistatic network limits the mutational reversibility in the influenza hemagglutinin receptor-binding site.,Wu NC, Thompson AJ, Xie J, Lin CW, Nycholat CM, Zhu X, Lerner RA, Paulson JC, Wilson IA Nat Commun. 2018 Mar 28;9(1):1264. doi: 10.1038/s41467-018-03663-5. PMID:29593268^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Wu NC, Thompson AJ, Xie J, Lin CW, Nycholat CM, Zhu X, Lerner RA, Paulson JC, Wilson IA. A complex epistatic network limits the mutational reversibility in the influenza hemagglutinin receptor-binding site. Nat Commun. 2018 Mar 28;9(1):1264. doi: 10.1038/s41467-018-03663-5. PMID:29593268 doi:http://dx.doi.org/10.1038/s41467-018-03663-5