Giant unilamellar vesicles (GUVs), consisting of ternary mixtures of soy-PC, sitosterol, and Glucosylceramide (GlcCer), spontaneously phase separate producing single large, microscopic monodomains. Imaging the domain texture of these GUVs using phase-sensitive complementary fluorescent probe confirms the fluid-fluid co-existence characterized by the macroscopic separation of the sterol-GlcCer enriched, liquid-ordered (lo) phase from the liquid-disordered (ld) phase consisting primarily of soy-PC. When rendered tense, such as by osmotic swelling, these vesicles produce a remarkable breathing/squeezing pattern characterized by the periodic appearance of transient microscopic pores at the domain boundaries and concomitant sequence of transient budding of the ld-phase domains. The former, transient poration, reflects the reduced activation energy for pore nucleation at the domain boundaries and the latter, periodic budding, emerges as a consequence of the balance of line (or edge) tension at the domain boundaries and the curvature energy of the ld phase domain. Furthermore, when subject to osmotic deflation through exposure to hypertonic solution, the ld phase domains bud and under certain conditions transform the bud into a complete bud, pinching of a single daughter vesicle composed of the ld-phase components. This budding to vesiculation transition indicates that the lateral tension exerted by the budding domain on the surrounding membrane of the mother vesicle can exceed the lysis tension. Taken together, these results illustrate the important roles of membrane compositional heterogeneity and domain texture in enabling fundamental processes of membrane poration, budding, and vesiculation, which enable fundamental biological processes of endocytosis, exocytosis, and barrier functions of bilayer membranes.

Phase separation and curvature generation in biphasic giant lipid vesicles reconstituting plant plasma membrane lipids

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.