Using DOPC-cholesterol giant unilamellar vesicles, the paper demonstrates that the N-terminal region of α‑synuclein is required for membrane binding and vesicle clustering, while full-length and C‑terminal truncated forms promote clustering and membrane permeabilization, with monomers causing…

By pinpointing the N-terminus as essential for membrane interaction and showing variant-dependent pore formation, the work provides a mechanistic handle that could guide strategies to block α‑synuclein–membrane binding and reduce membrane permeabilization implicated in Parkinson’s disease pathology.

Alpha-synuclein (α-syn), a presynaptic neuronal protein, is believed to play significant roles in Parkinson's disease (PD), the second most common neurodegenerative disorder. An aberrant aggregation of fibrillar form within Lewy bodies is the main neuropathological characteristic of PD. The interaction of α-syn with cellular membranes, as well as binding of α-syn to these membranes is crucial in the process of accumulations. In this study, we explored the aggregation behaviour of α-syn in both its monomeric and fibrillar forms when exposed to giant unilamellar vesicles (GUVs) composed of DOPC-cholesterol (10 mol%). We also investigated N-terminal (ΔN) and C-terminal (ΔC) truncated variants of α-syn to better understand the role of these end terminal regions on vesicle clustering and pore formation in GUVs. Both the full-length and ΔC forms of α-syn, whether in monomeric or fibrillar states, exhibited vesicle clustering. In contrast, the ΔN variant exhibited behaviour akin to a system devoid of α-syn, underscoring its critical role in mediating the interaction of α-syn with the membrane. In addition to vesicle clustering, we also observed membrane leakage induced by both the ΔC and full chain conformations of α-syn. The permeation rate of GUVs in the presence of monomeric α-syn was found to be higher than that associated with the fibrillar form of α-syn. Our research suggests that the variant of α-syn inhibits vesicle clustering and shows the least impact on permeation kinetics, thereby offering a potential strategy to understand the pathophysiology associated with PD.