Kinetics of Ganglioside-Rich Supported Lipid Bilayer Formation with Tracer Vesicle Fluorescence Imaging

Gangliosides, forming a class of lipids complementedby sugar chains,influence the lateral distribution of membrane proteins or membrane-bindingproteins, act as receptors for viruses and bacterial toxins, and mediateseveral types of cellular signaling. Gangliosides incorporated intosupported lipid bilayers (SLBs) have been widely applied as a modelsystem to examine these biological processes. In this work, we exploredhow ganglioside composition affects the kinetics of SLB formationusing the vesicle rupturing method on a solid surface. We imaged theattachment of vesicles and the subsequent SLB formation using thetime-lapse total internal reflection fluorescence microscopy technique.In the early phase, the ganglioside type and concentration influencethe adsorption kinetics of vesicles and their residence/lifetime onthe surface before rupturing. Our data confirm that a simultaneousrupturing of neighboring surface-adsorbed vesicles forms microscopiclipid patches on the surface and it is triggered by a critical coverageof the vesicles independent of their composition. In the SLB growthphase, lipid patches merge, forming a continuous SLB. The propagationof patch edges catalyzes the process and depends on the gangliosidetype. Our pH-dependent experiments confirm that the polar/chargedhead groups of the gangliosides have a critical role in these stepsand phases of SLB formation kinetics.

Automated summary

In this study, we investigated how ganglioside composition affects the kinetics of supported lipid bilayer (SLB) formation using the vesicle rupturing method on a solid surface. We observed the attachment of vesicles and the subsequent SLB formation using time-lapse total internal reflection fluorescence microscopy. The type and concentration of gangliosides were found to influence the adsorption kinetics of vesicles and their lifetime on the surface before rupturing. Additionally, the simultaneous rupturing of surface-adsorbed vesicles formed microscopic lipid patches on the surface, which was triggered by a critical coverage of vesicles independent of their composition.