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The AB 5 type toxin produced by the Vibrio cholerae bacterium is the causative agent of the cholera disease. The cholera toxin (CT) has been shown to bind specifically to GM1 glycolipids on the membrane surface. This binding of CT to the membrane is the initial step in its endocytosis and has been postulated to cause significant disruption to the membrane structure. In this work, we have carried out a combination of coarse-grain and atomistic simulations to study the binding of CT to a membrane modelled as an asymmetrical GM1-DPPC bilayer. Simulation results indicate that the toxin binds to the membrane through only three of its five B subunits, in effect resulting in a tilted bound configuration. Additionally, the binding of the CT can increase the area per lipid of GM1 leaflet, which in turn can cause the membrane regions interacting with the bound subunits to experience significant bilayer thinning and lipid tail disorder across both the leaflets. [ABSTRACT FROM AUTHOR]

The properties of lipid bilayers in contact with trehalose solutions in water were studied in the full concentration range using molecular dynamics simulations. The mechanism of trehalose interaction with the bilayer surface was analysed considering hydrogen bonding and molecular arrangements as well as the possible changes in bilayer properties. The effect of concentration of the possible mechanisms of trehalose action as membrane protectant were discussed to infer the possible evolution of water replacement by trehalose at the membrane surface and its relationship with the trehalose role in anhydrobiosis and drying processes. Unlabelled Image • Anhidrobiosis in presence of trehalose • Trehalose solution in presence interacting with lipid membranes • Water replacement mechanisms • Intermolecular forces at lipid bilayer interfaces • Nanoscopic characterization of bilayer structuring upon water replacement [ABSTRACT FROM AUTHOR]