Asymmetric Oxidation of Giant Vesicles triggers Curvature-associated Shape Transition and Permeabilization. Running title: Oxidation of Vesicles produces Curvature

TL;DR

This study demonstrates that asymmetric oxidation of giant vesicles induces curvature changes, shape transitions, and permeabilization, revealing how oxidative processes affect membrane biophysics and potentially cell function.

Contribution

It introduces a novel method of asymmetric lipid oxidation in giant vesicles and links oxidation-induced curvature changes to membrane permeabilization and fusogenicity.

Findings

Oxidation causes shape transitions like oblate to prolate and budding.

Permeabilization occurs after a lag phase and relates to oxidation levels.

Oxidation increases fusogenicity of vesicles.

Abstract

(200 words) 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.