Structural characterization of copper(Ⅱ) binding to α-synuclein: Insights into the bioinorganic chemistry of Parkinson's disease

摘要

The aggregation of α-synuclein (AS) is characteristic of Parkinson's disease and other neurodegenerative synucleinopathies. We demonstrate here that Cu(Ⅱ) ions are effective in accelerating AS aggregation at physiologically relevant concentrations without altering the resultant fibrillar structures. By using numerous spec-troscopic techniques (absorption, CD, EPR, and NMR), we have located the primary binding for Cu(Ⅱ) to a specific site in the N terminus, involving His-50 as the anchoring residue and other nitrogen/oxygen donor atoms in a square planar or distorted tetragonal geometry. The carboxylate-rich C terminus, originally thought to drive copper binding, is able to coordinate a second Cu(Ⅱ) equivalent, albeit with a 300-fold reduced affinity. The NMR analysis of AS-Cu(Ⅱ) complexes reveals the existence of confor-mational restrictions in the native state of the protein. The metal-lobiology of Cu(Ⅱ) in Parkinson's disease is discussed by a comparative analysis with other Cu(Ⅱ)-binding proteins involved in neurodegenerative disorders.