6Y5G image
Entry Detail
PDB ID:
6Y5G
EMDB ID:
Keywords:
Title:
Ectodomain of X-31 Haemagglutinin at pH 8
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2020-02-25
Release Date:
2020-06-10
Method Details:
Experimental Method:
Resolution:
3.00 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:X-31 Influenza Haemagglutinin HA1
Chain IDs:A, C, D (auth: E)
Chain Length:318
Number of Molecules:3
Biological Source:unidentified influenza virus
Polymer Type:polypeptide(L)
Description:X-31 Influenza Haemagglutinin HA2
Chain IDs:B, E (auth: D), F
Chain Length:172
Number of Molecules:3
Biological Source:unidentified influenza virus
Ligand Molecules
Primary Citation
Structural transitions in influenza haemagglutinin at membrane fusion pH.
Nature 583 150 153 (2020)
PMID: 32461688 DOI: 10.1038/s41586-020-2333-6

Abstact

Infection by enveloped viruses involves fusion of their lipid envelopes with cellular membranes to release the viral genome into cells. For HIV, Ebola, influenza and numerous other viruses, envelope glycoproteins bind the infecting virion to cell-surface receptors and mediate membrane fusion. In the case of influenza, the receptor-binding glycoprotein is the haemagglutinin (HA), and following receptor-mediated uptake of the bound virus by endocytosis1, it is the HA that mediates fusion of the virus envelope with the membrane of the endosome2. Each subunit of the trimeric HA consists of two disulfide-linked polypeptides, HA1 and HA2. The larger, virus-membrane-distal, HA1 mediates receptor binding; the smaller, membrane-proximal, HA2 anchors HA in the envelope and contains the fusion peptide, a region that is directly involved in membrane interaction3. The low pH of endosomes activates fusion by facilitating irreversible conformational changes in the glycoprotein. The structures of the initial HA at neutral pH and the final HA at fusion pH have been investigated by electron microscopy4,5 and X-ray crystallography6-8. Here, to further study the process of fusion, we incubate HA for different times at pH 5.0 and directly image structural changes using single-particle cryo-electron microscopy. We describe three distinct, previously undescribed forms of HA, most notably a 150 Å-long triple-helical coil of HA2, which may bridge between the viral and endosomal membranes. Comparison of these structures reveals concerted conformational rearrangements through which the HA mediates membrane fusion.

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