Lipid Species Dependent Vesicles Clustering Caused by alpha-Synuclein as Revealed by Single-Vesicle Imaging with Total Internal Reflection Fluorescence Microscopy

Single-molecule methods have been applied to study the mechanisms of many bio-physical systems that occur on the nanometer scale. To probe the dynamics of the such systems including vesicle docking, tethering, fusion, trafficking, protein-membrane interactions, etc., and to obtain reproducible experimental data; proper methodology and framework are crucial. Here, we address this need by developing a protocol for immobilization of vesicles composed of synthetic lipids and measurement using total internal reflection fluorescence (TIRF) microscopy. Furthermore, we demonstrate applications including vesicle clustering mediated by proteins such as alpha-Synuclein (αSyn) and the influence of external ions by using TIRF microscopy. Moreover, we use this method to quantify the dependence of lipid composition and charge on vesicle clustering mediated by αSyn which is based on the methods previously reported.