Analysis of Physicochemical Interaction of Aβ40 with a GM1 Ganglioside-Containing Lipid Membrane

The interaction of amyloid beta (A beta) peptides with the cell membrane is one of the factors enhancing A beta aggregation, which is closely related to neurodegenerative disease. In this work, we performed molecular dynamics (MD) simulation to investigate the initial stage of adhesion of A beta(40) to a GM1 ganglioside-containing membrane. Conformational change of A beta(40) due to interaction with the membrane was monitored and compared with that of A beta(42) observed in the previous study. Multiple computational trials were executed to analyze the probability of A beta binding using a calculation model consisting of a GM1-containing mixed lipid membrane, a water layer, ions, and A beta(40). A single long-time MD simulation was also carried out. It was suggested from the simulation that a cluster of sialic acids of GM1 head groups often caught the side chain of His13 or His14 of A beta(40) in the early stage of the MD simulations. Afterward, the main chain of Leu34 formed many hydrogen bonds with gangliosides. These residues cooperatively work for A beta(40) to be held on the lipid membrane. It is notable that A beta(40) was observed to be deeply inserted into the head group region of the lipid membrane in some computational trials. In the insertion, A beta(40) occasionally formed a hydrogen bond with sphingomyelin. The difference in the secondary structure between A beta(40) and A beta(42) was an important factor for A beta(40) to be deeply inserted into the membrane.