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

Abstract

Gangliosides, forming a class of lipids complemented by sugar chains, influence the lateral distribution of membrane proteins or membrane-binding proteins, act as receptors for viruses and bacterial toxins, and mediate several types of cellular signaling. Gangliosides incorporated into supported lipid bilayers (SLBs) have been widely applied as a model system to examine these biological processes. In this work, we explored how ganglioside composition affects the kinetics of SLB formation using the vesicle rupturing method on a solid surface. We imaged the attachment of vesicles and the subsequent SLB formation using the time-lapse total internal reflection fluorescence microscopy technique. In the early phase, the ganglioside type and concentration influence the adsorption kinetics of vesicles and their residence/lifetime on the surface before rupturing. Our data confirm that a simultaneous rupturing of neighboring surface-adsorbed vesicles forms microscopic lipid patches on the surface and it is triggered by a critical coverage of the vesicles independent of their composition. In the SLB growth phase, lipid patches merge, forming a continuous SLB. The propagation of patch edges catalyzes the process and depends on the ganglioside type. Our pH-dependent experiments confirm that the polar/charged head groups of the gangliosides have a critical role in these steps and phases of SLB formation kinetics.

Synergistic Binding of SARS-CoV-2 to ACE2 and Gangliosides in Native Lipid Membranes

“…SMBs were formed by the vesicle fusion and rupturing method, and their composition was controlled by injecting MVs followed by DOPC vesicles with or without 0.98 mol % GD1a on a cleaned borosilicate glass surface (scheme in Figure A-ii). This method of SMB formation has been adopted from prior research conducted by Daniel’s lab ,,, and other research groups. , The assessment of SMB formation was done using the tracer vesicle imaging approach (Figure S1D), a method pioneered by the Hook lab − and subsequently adopted by various research groups, including our own . The composition of MV+DOPC and MV+GD1a SMBs is influenced by the volume ratio of the injected MVs to DOPC/GD1a vesicles.…”