Fluorophore position of headgroup-labeled Gb < sub > 3 < /sub > glycosphingolipids in lipid bilayers

Biophys J. 2023 Sep 21:S0006-3495(23)00587-8. doi: 10.1016/j.bpj.2023.09.010. Online ahead of print.ABSTRACTFluorescent lipid probes are an invaluable tool for investigating lipid membranes. In particular, localizing particular receptor lipids such as glycosphingolipids within phase-separated membranes is of pivotal interest to understanding the influence of protein-receptor lipid binding on membrane organization. However, fluorescent labeling can readily alter the phase behavior of a lipid membrane because of the interaction of the fluorescent moiety with the membrane interface. Here, we investigated Gb3 glycosphingolipids, serving as receptor lipids for the protein Shiga toxin, with a headgroup attached BODIPY fluorophore separated by a polyethylene glycol (PEG) spacer of different lengths. We found that the diffusion coefficients of the fluorescently labeled Gb3 species in DOPC/Gb3 (98:2, n/n) supported lipid bilayers are unaltered by the PEG spacer length. However, quenching as well as graphene-induced energy transfer (GIET) experiments indicate that the length of the PEG spacer (n = 3 and n = 13) alters the position of the BODIPY fluorophore. In particular, the GIET technique provided accurate end-to-end distances between the fluorophores in the two leaflets of the bilayer thus enabling us to quantify the distance between the membrane interface and the fluorophore with sub-nanometer resolution. The spacer with three oligo ethylene glycol groups positioned the BODIPY fluo...
Source: Biophysical Journal - Category: Physics Authors: Source Type: research