Ratiometric Fluorescent ESIPT Probe Characterizes Binding of Alpha-Synuclein to Membranes

Abstract

The aggregation of the protein α-synuclein (AS) is involved in the pathogenesis of Parkinson's disease. Evidence suggests that neurotoxicity may originate from the binding of oligomeric AS to cellular membranes, resulting in disruption and cell leakage. Defining the interactions of AS with membranes is thus essential for understanding its physiological and pathological functions.For such studies, we developed a cysteine-reactive label (MFE) that senses protein microenvironment via the ratio of two emission bands resulting from Excited State Intramolecular Proton Transfer (ESIPT) [1]. We labeled AS at different positions (ala-to-cysteine mutations) and compared the binding to model membranes and the immersion level of its domains. AS has a greater affinity for membranes with high curvature (SUVs) than to LUVs and for negatively-charged than to neutral membranes. We are currently studying the binding of AS oligomers and the impact of membranes on AS aggregation. For other related studies see refs. [2-4].[1] Demchenko et al (2009) Biophys J 96: 3461; [2] Celej et al. (2009) Biochemistry 48: 7465; [3] Caarls et al. (2009) J Fluor DOI 10.1007/s10895-009-0536-1; [4] posters by Yushchenko et al. and Fauerbach et al.View Large Image | View Hi-Res Image | Download PowerPoint Slide