Asymmetric oxidation of giant vesicles triggers curvature-associated shape transition and permeabilization.
Oxidation of unsaturated lipids is a fundamental process involved in cell bioenergetics as well as in cell death. Using giant unilamellar vesicles and a chlorin photosensitizer, we asymmetrically oxidized the outer or inner monolayers of lipid membranes. We observed different shape transitions such as oblate to prolate and budding, which are typical of membrane curvature modifications. The asymmetry of the shape transitions is in accordance with a lowered effective spontaneous curvature of the leaflet being targeted. We interpret this effect as a decrease in the preferred area of the targeted leaflet compared to the other, due to the secondary products of oxidation (cleaved-lipids). Permeabilization of giant vesicles by light-induced oxidation is observed after a lag and is characterized in relation with the photosensitizer concentration. We interpret permeabilization as the opening of a pore above a critical membrane tension, resulting from the budding of vesicles. The evolution of photosensitized giant vesicle lysis tension was measured and yields an estimation of the effective spontaneous curvature at lysis. Additionally photo-oxidation was shown to be fusogenic.
Heuvingh
Julien
J
Université Paris Diderot, Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR7636, Centre National de la Recherche Scientifique/Ecole Superieure Physique Chimie Industrielles Ville de Paris, Université Pierre et Marie Curie, Paris, France. julien.heuvingh@espci.fr
Bonneau
Stéphanie
S
D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000378:metabolism; D055668:Photochemical Processes; D017319:Photosensitizing Agents / Q000494:pharmacology; D053835:Unilamellar Liposomes / Q000737:chemistry* / Q000378:metabolism*
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D017319:Photosensitizing Agents; D053835:Unilamellar Liposomes; C017251:1,2-oleoylphosphatidylcholine