VAMP2 regulates phase separation of alpha-synuclein

Summary Alpha-synuclein (aSYN) is a small synaptic protein that is linked to Parkinson’s disease (PD) and other synucleinopathies. aSYN has been shown to undergo protein phase separation. We found that aSYN phase separation, in vitro and in cells, is regulated by vesicle-associated membrane protein 2 (VAMP2), the vesicular SNARE protein. We show that aSYN phase separation is promoted by C-terminal electrostatic interaction, which in cells is mediated via interaction with VAMP2. The condensate formation is specific for the R-SNARE VAMP2 and critically dependent on aSYN’s capacity to bind to lipid membranes. In vitro, the addition of VAMP2 decreases the saturation concentration of aSYN phase separation, which is mediated by its juxtamembrane domain. Our results delineate a molecular mechanism for the regulation of aSYN phase separation, indicating a potential switch from the dispersed to the phase-separated state during vesicle cycling. Highlights ### Competing Interest Statement The authors have declared no competing interest.