Membrane fusion in vesicles of oligomerizable lipids.
Membrane fusion has been examined in a model system of small unilamellar vesicles of synthetic lipids that can be oligomerized through the lipid headgroups. The oligomerization can be induced either in both bilayer leaflets or in the inner leaflet exclusively. Oligomerization leads to denser lipid headgroup packing, with concomitant reduction of lipid lateral diffusion and membrane permeability. As evidenced by lipid mixing assays, electron microscopy, and light scattering, calcium-induced fusion of the bilayer vesicles is strongly retarded and inhibited by oligomerization. Remarkably, oligomerization of only the inner leaflet of the bilayer is already sufficient to affect fusion. The efficiency of inhibition and retardation of fusion critically depend on the relative amount of oligomeric lipid present, on the concentration of calcium ions, and on temperature. Implications for the mechanism of bilayer membrane fusion are discussed in terms of lipid lateral diffusion and membrane curvature effects.
Ravoo
B J
BJ
Department of Organic and Molecular Inorganic Chemistry and Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
Weringa
W D
WD
Engberts
J B
JB
D055592:Biophysical Phenomena; D001703:Biophysics; D002118:Calcium / Q000494:pharmacology; D004058:Diffusion; D004492:Edetic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy; D008561:Membrane Fusion / Q000187:drug effects / Q000502:physiology; D008563:Membrane Lipids / Q000737:chemistry*; D008854:Microscopy, Electron; D008954:Models, Biological; D012995:Solubility; D013816:Thermodynamics
D008051:Lipid Bilayers; D008081:Liposomes; D008563:Membrane Lipids; D004492:Edetic Acid; D002118:Calcium