Protein-Drug Interactions in the Membrane: The Small Molecule Anle138b and its Binding to α-Synuclein Oligomers

A physiological hallmark of neurodegenerative diseases is the presence of deposits in the patient's brain, which consist of various aggregates of abundant proteins such as amyloid-β (Alzheimer's Disease) or α-synuclein (Parkinson's Disease). Growing evidence suggests that transient oligomers, formed during the aggregation process, constitute the major toxic species. The 3,5-diphenyl-pyrazole derivative anle138b was shown to interfere with the processes associated with taupathies, Parkinson's, Alzheimer's and Prion Disease in related mouse models. The success of anle138b in vivo calls for an elucidation of the underlying mechanism in vitro. Thorough investigation of the kinetics of α-synuclein aggregation in the presence of phospholipid membranes allowed the enrichment of protein oligomers. We characterized these oligomers using AFM, EM and CD-spectroscopy and probed their functional relevance by planar lipid bilayer measurements. We confirmed a direct interaction between membrane-embedded anle138b and these oligomers using DNP-enhanced solid-state-NMR. This interaction was then characterized and specified using various labelling strategies. These findings reveal valuable information about the mechanism of not only the disease related proteins, but also potential therapeutic targets in the aggregation process