Site-Specific Copper-Catalyzed Oxidation of 伪-Synuclein: Tightening the Link between Metal Binding and Protein Oxidative Damage in Parkinson鈥檚 Disease

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• 作者：Marco C. Miotto ; Esa煤 E. Rodriguez ; Ariel A. Valiente-Gabioud ; Valentina Torres-Monserrat ; Andr茅s Binolfi ; Liliana Quintanar ; Markus Zweckstetter ; Christian Griesinger ; Claudio O. Fern谩ndez
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：May 5, 2014
• 年：2014
• 卷：53
• 期：9
• 页码：4350-4358
• 全文大小：435K
• 年卷期：v.53,no.9(May 5, 2014)
• ISSN：1520-510X

文摘

Amyloid aggregation of 伪-synuclein (AS) has been linked to the pathological effects associated with Parkinson鈥檚 disease (PD). Cu^II binds specifically at the N-terminus of AS and triggers its aggregation. Site-specific Cu^I-catalyzed oxidation of AS has been proposed as a plausible mechanism for metal-enhanced AS amyloid formation. In this study, Cu^I binding to AS was probed by NMR spectroscopy, in combination with synthetic peptide models, site-directed mutagenesis, and C-terminal-truncated protein variants. Our results demonstrate that both Met residues in the motif ¹MDVFM⁵ constitute key structural determinants for the high-affinity binding of Cu^I to the N-terminal region of AS. The replacement of one Met residue by Ile causes a dramatic decrease in the binding affinity for Cu^I, whereas the removal of both Met residues results in a complete lack of binding. Moreover, these Met residues can be oxidized rapidly after air exposure of the AS-Cu^I complex, whereas Met-116 and Met-127 in the C-terminal region remain unaffected. Met-1 displays higher susceptibility to oxidative damage compared to Met-5 because it is directly involved in both Cu^II and Cu^I coordination, resulting in closer exposure to the reactive oxygen species that may be generated by the redox cycling of copper. Our findings support a mechanism where the interaction of AS with copper ions leads to site-specific metal-catalyzed oxidation in the protein under physiologically relevant conditions. In light of recent biological findings, these results support a role for AS鈥揷opper interactions in neurodegeneration in PD.