Coordination Features and Affinity of the Cu2+ Site in the 伪-Synuclein Protein of Parkinson鈥檚 Disease

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• 作者：Christopher G. Dudzik ; Eric D. Walter ; Glenn L. Millhauser
• 刊名：Biochemistry
• 出版年：2011
• 出版时间：March 22, 2011
• 年：2011
• 卷：50
• 期：11
• 页码：1771-1777
• 全文大小：826K
• 年卷期：v.50,no.11(March 22, 2011)
• ISSN：1520-4995

文摘

Parkinson鈥檚 disease (PD) is the second most prevalent age-related, neurodegenerative disorder, affecting >1% of the population over the age of 60. PD pathology is marked by intracellular inclusions composed primarily of the protein 伪-synuclein (伪-syn). These inclusions also contain copper, and the interaction of Cu²⁺ with 伪-syn may play an important role in PD fibrillogenesis. Here we report the stoichiometry, affinity, and coordination structure of the Cu²⁺鈭捨?syn complex. Electron paramagnetic resonance (EPR) titrations show that monomeric 伪-syn binds 1.0 equiv of Cu²⁺ at the protein N-terminus. Next, an EPR competition technique demonstrates that 伪-syn binds Cu²⁺ with a K_d of 鈮?.10 nM. Finally, EPR and electron spin echo modulation (ESEEM) applied to a suite of mutant and truncated 伪-syn constructs reveal a coordination sphere arising from the N-terminal amine, the Asp2 amide backbone and side chain carboxyl group, and the His50 imidazole. The high binding affinity identified here, in accord with previous measurements, suggests that copper uptake and sequestration may be a part of 伪-syn鈥檚 natural function, perhaps modulating copper鈥檚 redox properties. The findings further suggest that the long-range interaction between the N-terminus and His50 may have a weakening effect on the interaction of 伪-syn with lipid membranes, thereby mobilizing monomeric 伪-syn and hastening fibrillogenesis.