Equilibrium-fluctuation-analysis of single liposome binding events reveals how cholesterol and Ca2+ modulate glycosphingolipid trans-interactions

• Published in: Scientific reports Vol. 3; no. 1; p. 1452
• Main Authors: Kunze, Angelika, Bally, Marta, Höök, Fredrik, Larson, Göran
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.03.2013; Nature Publishing Group
• Subjects: 631/57/2270; 631/61/2049; 639/638/45/56; 639/766/25; antigens; Calcium; Calcium - chemistry; Calcium - metabolism; Carbohydrate Sequence; carbohydrate-carbohydrate interactions; Cations; Cell membranes; cell-adhesion; Chemical Sciences; Cholesterol; Cholesterol - chemistry; Cholesterol - metabolism; Fluorescent Dyes - chemistry; Glycosphingolipids; Glycosphingolipids - chemistry; Glycosphingolipids - metabolism; Humanities and Social Sciences; Kemi; Kinetics; Lipid bilayers; Lipid Bilayers - chemistry; Lipid Bilayers - metabolism; Liposomes; Liposomes - chemistry; Liposomes - metabolism; membranes; mismatch discrimination; multidisciplinary; qcm-d; recognition; Science; supported lipid-bilayers; system; unilamellar vesicles
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep01452

Carbohydrate−carbohydrate interactions (CCIs) are of central importance for several biological processes. However, the ultra-weak nature of CCIs generates difficulties in studying this interaction, thus only little is known about CCIs. Here we present a highly sensitive equilibrium-fluctuation-analysis of single liposome binding events to supported lipid bilayers (SLBs) based on total internal reflection fluorescence (TIRF) microscopy that allows us to determine apparent kinetic rate constants of CCIs. The liposomes and SLBs both contained natural Le x glycosphingolipids (Galβ4(Fucα3)GlcNAcβ3Galβ4Glcβ1Cer), which were employed to mimic cell−cell contacts. The kinetic parameters of the self-interaction between Le x -containing liposomes and SLBs were measured and found to be modulated by bivalent cations. Even more interestingly, upon addition of cholesterol, the strength of the CCIs increases, suggesting that this interaction is strongly influenced by a cholesterol-dependent presentation and/or spatial organization of glycosphingolipids in cell membranes.