Meta-stability of the hemifusion intermediate induced by glycosylphosphatidylinositol-anchored influenza hemagglutinin
| Autor: | F. Nüssler, Michael J. Clague, Andreas Herrmann |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
Glycosylphosphatidylinositols
Lipid Bilayers Population Biophysics Hemagglutinin Glycoproteins Influenza Virus CHO Cells Biology Membrane Fusion Cell membrane Cricetinae medicine Animals Humans Inner membrane Trypsin Lipid bilayer education Fluorescent Dyes education.field_of_study Microscopy Confocal Rhodamines Phosphatidylethanolamines Cell Membrane Erythrocyte Membrane Lipid bilayer fusion Isoquinolines Transmembrane protein Transmembrane domain 4-Chloro-7-nitrobenzofurazan medicine.anatomical_structure Biochemistry Cytoplasm Phosphatidylcholines lipids (amino acids peptides and proteins) Research Article |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/S0006-3495(97)78260-2 |
| Popis: | Fusion between influenza virus and target membranes is mediated by the viral glycoprotein hemagglutinin (HA). Replacement of the transmembrane domain of HA with a glycosylphosphatidylinositol (GPI) membrane anchor allows lipid mixing but not the establishment of cytoplasmic continuity. This observation led to the proposal that the fusion mechanism passes through an intermediate stage corresponding to hemifusion between outer monolayers. We have used confocal fluorescence microscopy to study the movement of probes for specific bilayer leaflets of erythrocytes fusing with HA-expressing cells. N-Rh-PE and NBD-PC were used for specific labeling of the outer and inner membrane leaflet, respectively. In the case of GPI-HA-induced fusion, different behaviors of lipid transfer were observed, which include 1) exclusive movement of N-Rh-PE (hemifusion), 2) preferential movement of N-Rh-PE relative to NBD-PC, and 3) equal movement of both lipid analogs. The relative population of these intermediate states was dependent on the time after application of a low pH trigger for fusion. At early time points, hemifusion was more common and full redistribution of both bilayers was rare, whereas later full redistribution of both probes was frequently observed. In contrast to wild-type HA, the latter was not accompanied by mixing of the cytoplasmic marker Lucifer Yellow. We conclude that 1) the GPI-HA-mediated hemifusion intermediate is meta-stable and 2) expansion of an aqueous fusion pore requires the transmembrane and/or cytoplasmic domain of HA. |
| Databáze: | OpenAIRE |
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