Distinct Effect of the Pathogenic Mutations on -Synuclein Aggregation in the Presence of Lipid Vesicles

The misfolding and self-assembly of a-synuclein into fibrillar aggregates are closely linked to Parkinson's Disease (PD) and related dementia. Emerging evidence indicates that intermediate states, particularly small oligomers, formed during the misfolding process are the major toxic species. Despite the importance of characterizing these small oligomers to better understand the molecular mechanisms of misfolding, their biophysical study has been hindered by the absence of dependable methods for generating diverse oligomeric forms. In this work, we describe distinct small misfolded oligomers generated from Wild-Type (WT) and pathogenic variants (A53T and G51D) of a-synuclein, which were produced by using lipid vesicles at pH 7.4. Our findings indicate that single-point mutations affect the aggregation behavior of a-synuclein under the influence of Cardiolipin (CL)-containing vesicles, a key component of mitochondrial membranes. Structural analysis via Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) revealed that these oligomers display distinct structural and dynamic characteristics. These structurally unique oligomers will be of great use in investigating the structure-function relationship of misfolded oligomers in neurodegenerative diseases.