Electron microscopy of the low pH structure of influenza virus haemagglutinin

• Published in: The EMBO journal Vol. 5; no. 1; pp. 41 - 49
• Main Authors: Ruigrok, R.W., Wrigley, N.G., Calder, L.J., Cusack, S., Wharton, S.A., Brown, E.B., Skehel, J.J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01.01.1986
• Subjects: Animals; Biological and medical sciences; Chick Embryo; electron microscopy; Fundamental and applied biological sciences. Psychology; hemagglutinins; Hemagglutinins, Viral - analysis; Hydrogen-Ion Concentration; influenza virus; Microbiology; Microscopy, Electron; Molecular Weight; Morphology, structure, chemical composition, physicochemical properties; Neutrons; Orthomyxoviridae - physiology; Peptide Fragments - analysis; Scattering, Radiation; Trypsin; Virology; Hemagglutinin; Hydrodynamic method; Conformational dynamics; Orthomyxoviridae; Electron microscopy; Influenzavirus; Structure function relationship; Virus; Adsorption; Neutron scattering; PH; Mechanism of action; Conformation
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1986.tb04175.x

Influenza virus haemagglutinin mediates infection of cells by fusion of viral and endosomal membranes, triggered by low pH which induces a conformational change in the protein. We report studies of this change by electron microscopy, neutron scattering, sedimentation and photon correlation on X‐31 (H3N2) haemagglutinin, both intact and bromelain cleaved, in various assemblies. HAs in all preparations showed a thinning at low pH, and a marked elongation which was removed on tryptic digestion, revealing altered features in the remaining stem portion of the molecule. A tentative model of the change is proposed, with reference to the known X‐ray structure at neutral pH, in which major changes occur in the stem tertiary structure, while the top portion is only affected in its quaternary structure.