Two Different Binding Modes of α-Synuclein to Lipid Vesicles Depending on its Aggregation State

Aggregation of alpha-synuclein is involved in the pathogenesis of Parkinson's disease (PD). Studies. of in vitro aggregation of alpha-synuclein are rendered complex because of the formation of a heterogeneous population of oligomers. With the use of confocal single-molecule fluorescence techniques, we demonstrate that small aggregates (oligomers) of alpha-synuclein formed from unbound monomeric species in the presence of organic solvent (DMSO) and iron (Fe3+) ions have a high affinity to bind to model membranes, regardless of the lipid-composition or membrane curvature. This binding mode contrasts with the well-established membrane binding of alpha-synuclein monomers, which is accompanied with alpha-helix formation and requires membranes with high curvature, defects in the lipid packing, and/or negatively charged lipids. Additionally, we demonstrate that membrane-bound alpha-synuclein monomers are protected from aggregation. Finally, we identified compounds that potently dissolved vesicle-bound alpha-synuclein oligomers into monomers, leaving the lipid vesicles intact. As it is commonly believed that formation of oligomers is related PD progression, such compounds may provide a promising strategy for the design of novel therapeutic drugs in Parkinson's disease.