Human Islet Amyloid Polypeptide Hiapp Monomer And Dimer Interact With Popg Lecithin Membrane Of Molecular Dynamics Simulation Study

The aggregation of human islet amyloid polypeptide (hIAPP or amylin) is associated with the pathogenesis of type2diabetes mellitus. Increasing evidence suggests that the interaction of hIAPP with β-cell membranes plays a crucial role in cytotoxicity. However, the molecular mechanism of interaction and subsequent membrane perturbation at atomic level remains poorly understood. In this study, as a first step to understand the mechanism of hIAPP-induced cytotoxicity, we have investigated the detailed interactions of hIAPP monomer and dimer with anionic palmitoyloleolyophosphatidylglycerol (POPG) bilayer using all-atom molecular dynamics (MD) simulations. Multiple MD simulations have been performed by employing the initial configurations where the N-terminal region of hIAPP is pre-inserted in POPG bilayer. Our simulations show that electrostatic interaction between hIAPP and POPG bilayer plays a major role in peptide-lipid interaction. In particular, the N-terminal positively-charged residues Lysl and Argil make a dominant contribution to the interaction. During peptide-lipid interaction process, peptide dimerization occurs mostly through the C-terminal20-37region containing the amyloidogenic20-29-residue segment. Membrane-bound hIAPP dimers display a pronounced ability of membrane perturbation than monomers. The higher bilayer perturbation propensity of hIAPP dimer likely results from the cooperativity of the peptide-peptide interaction (or peptide aggregation). This study provides insight into the hIAPP-membrane interaction and the molecular mechanism of membrane disruption by hIAPP oligomers.