1,2-Dioleoylglycerol promotes calcium-induced fusion in phospholipid vesicles.
The effect of 1,2-dioleoyglycerol (1,2-DOG) on the promotion of Ca(2+)-induced fusion of phosphatidylserine/phosphatidylcholine (PS/PC) vesicles was studied. 1,2-DOG is able to induce the mixing of membrane lipids at concentrations of 10 mol% without mixing of vesicular contents. At concentrations of 20 mol% or higher, 1,2-DOG promotes fusion, lipid and content mixing, of LUV composed of an equimolar mixture of PS and PC, which otherwise are unable to fuse in the presence of Ca2+. Fusion was demonstrated by fluorescence assays monitoring mixing of aqueous vesicular contents and mixing of membrane lipids. Studies by Fourier transform infrared spectroscopy provided evidence for a fusion mechanism different to that of Ca(2+)-induced fusion of pure PS vesicles. Final equilibrium structures were characterized by 31P-NMR and freeze-fracture electron microscopy. Ca(2+)-induced fusion of 1,2-DOG containing vesicles is accompanied by the formation of isotropic structures which are shown to correspond to structures with lipidic particle morphology. The possible fusion mechanisms and implications are discussed.
Ortiz
A
A
Departamento de Bioquímica y Biología Molecular A, Universidad de Murcia, Spain.
Aranda
F J
FJ
Villalaín
J
J
San Martín
C
C
Micol
V
V
Gómez-Fernandez
J C
JC
D002118:Calcium; D004075:Diglycerides; D005583:Fourier Analysis; D005614:Freeze Fracturing; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008561:Membrane Fusion; D008854:Microscopy, Electron; D010713:Phosphatidylcholines / Q000737:chemistry*; D010718:Phosphatidylserines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013055:Spectrophotometry, Infrared
D004075:Diglycerides; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D002118:Calcium; C013965:diolein