Lipid Lateral Mobility and Membrane Phase Structure Modulation by Protein Binding

Abstract

Using a combination of fluorescence correlation and infrared absorption spectroscopies, we characterize lipid lateral diffusion and membrane phase structure as a function of protein binding to the membrane surface. In a supported membrane configuration, cholera toxin binding to the pentasaccharaide headgroup of membrane-incorporated GM1 lipid alters the long-range lateral diffusion of fluorescently labeled probe lipids, which are not involved in the binding interaction. This effect is prominently amplified near the gel-fluid transition temperature, Tm, of the majority lipid component. At temperatures near Tm, large changes in probe lipid diffusion are measured at average protein coverage densities as low as 0.02 area fraction. Spectral shifts of the methylene symmetric and asymmetric stretching modes in the lipid acyl chain confirm that protein binding alters the fraction of lipid in the gel phase.

Molecular mechanisms in signal transduction at the membrane

“…For one, this amplifies the response of the membrane to any sort of perturbation (for example, electrostatic, mechanical or interactions with proteins). Such effects have been experimentally observed for proteins binding to membrane surfaces [29][30][31] , including actin polymerization 32 and for electric field-induced membrane reorganization 33 . More generally, the way the membrane solvates other components, such as membrane proteins, and even mediates their interactions with each other will be affected by these intrinsic properties.…”

Interfacing Zwitterionic Liposomes with Inorganic Nanomaterials: Surface Forces, Membrane Integrity, and Applications

“…45 Protein adsorption was also reported. 46 We studied graphene oxide, nanodiamond, a few metal oxides, and here MPA and GSH-capped AuNPs. 43,44,47 None of them leaked PC liposomes.…”

Lipid-Mediated Endocytosis

“…Why the diffusion of lipid-bound ligands is reduced to such an extent is not clear, especially because the binding of antibody to lipids does not result in a similar reduction (Lee et al 1991). Interestingly, the binding of cholera toxin to GM1 strongly reduces the diffusion of other lipid molecules in the same membrane (Forstner et al 2006). The binding interface between CTX and SV40 pentamers and the membrane is quite tight, with the protein surface contacting the top bilayer leaflet (Campanero-Rhodes et al 2007;Neu et al 2008).…”

“…It also leads to lateral segregation of CTX-containing liquid-ordered membrane domains from more liquid-disordered membrane both in PM-blebs (Lingwood et al 2008) and in artificial membranes (Hammond et al 2005). Binding of CTX also increases the melting temperature (Forstner et al 2006) and viscosity (Yamazaki et al 2005) of supported membrane bilayers. Furthermore, after binding to the PM of cells, CTX, STX, and SV40 are found to associate with detergentresistant membranes (DRM) (Falguieres et al 2001;Wolf et al 2002;Damm et al 2005).…”