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Protein-induced fusion of phospholipid vesicles of heterogeneous sizes
B F de Arcuri1, G F Vechetti, R N Chehín
1Instituto Superior de Investigaciones Biológicas, Instituto de Química Biológica "Dr. B. Bloj," Facultad de Bioquímica, Química y Farmacia (CONICET/UNT), Chacabuco 461, S.M. de Tucumán, 4000, Argentina.
Abstract:
We have investigated the fusion of phospholipid vesicles induced by lysozyme and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Vesicles were composed of dimyristoylphosphatidylcholine/dioleoylphosphatidylethanolamine/ cholesterol (DMPC:DOPE:Chol, 2:1:1). Small unilamellar vesicles (SUV, diameter ca. 30 nm) obtained by extensive sonication or large unilamellar vesicles (LUV, diameters ranged from 100 to 400 nm) obtained by extrusion methods were used. Fusion of LUV induced by lysozyme and GAPDH was drastically decreased when the diameter of the vesicles increased over a value of 100 nm. Lysozyme effect was stopped at the aggregation step while GAPDH effect was stopped at the fusion (lipid mixing) step. Fusion of heterogeneous vesicle populations (SUV with LUV) was observed only with GAPDH and this happened only when the lipids were in the liquid-crystalline state.