Kinetic stabilization of the alpha-synuclein protofibril by a dopamine-alpha-synuclein adduct.

The substantia nigra in Parkinson's disease (PD) is depleted of dopaminergic neurons and contains fibrillar Lewy bodies comprising primarily alpha-synuclein. We screened a library to identify drug-like molecules to probe the relation between neurodegeneration and alpha-synuclein fibrilization. All but one of 15 fibril inhibitors were catecholamines related to dopamine. The inhibitory activity of dopamine depended on its oxidative ligation to alpha-synuclein and was selective for the protofibril-to-fibril conversion, causing accumulation of the alpha-synuclein protofibril. Adduct formation provides an explanation for the dopaminergic selectivity of alpha-synuclein-associated neurotoxicity in PD and has implications for current and future PD therapeutic and diagnostic strategies.