Amyloid β-peptide insertion in liposomes containing GM1-cholesterol domains

Neuronal membrane damage is related to the early impairments appearing in Alzheimer's disease due to the interaction of the amyloid beta-peptide (A beta) with the phospholipid bilayer. In particular, the ganglioside GM1, present with cholesterol in lipid rafts, seems to be able to initiate A beta aggregation on membrane. We studied the thermodynamic and structural effects of the presence of GM1 on the interaction between A beta and liposomes, a good membrane model system. Isothermal Titration Calorimetry highlighted the importance of the presence of GM1 in recruiting monomeric A beta toward the lipid bilayer. Light and Small Angle X-ray Scattering revealed a different pattern for GM1 containing liposomes, both before and after interaction with A beta. The results suggest that the interaction with GM1 brings to insertion of A beta in the bilayer, producing a structural perturbation down to the internal layers of the liposome, as demonstrated by the obtained electron density profiles. (C) 2015 Elsevier B.V. All rights reserved.