The Octarepeat Domain of the Prion Protein Binds Cu(II) with Three Distinct Coordination Modes at pH 7.4

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• 作者：Madhuri Chattopadhyay ; Eric D. Walter ; Dustin J. Newell ; Pilgrim J. Jackson ; Eliah Aronoff-Spencer ; Jack Peisach ; Gary J. Gerfen ; Brian Bennett ; William E. Antholine ; and Glenn L. Millhauser
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：September 14, 2005
• 年：2005
• 卷：127
• 期：36
• 页码：12647 - 12656
• 全文大小：196K
• 年卷期：v.127,no.36(September 14, 2005)
• ISSN：1520-5126

文摘

The prion protein (PrP) binds Cu²⁺ in its N-terminal octarepeat domain. This unusual domain iscomprised of four or more tandem repeats of the fundamental sequence PHGGGWGQ. Previous workfrom our laboratories demonstrates that at full copper occupancy, each HGGGW segment binds a singleCu²⁺. However, several recent studies suggest that low copper occupancy favors different coordinationmodes, possibly involving imidazoles from histidines in adjacent octapeptide segments. This is investigatedhere using a combination of X-band EPR, S-band EPR, and ESEEM, along with a library of modified peptidesdesigned to favor different coordination interactions. At pH 7.4, three distinct coordination modes areidentified. Each mode is fully characterized to reveal a series of copper-dependent octarepeat domainstructures. Multiple His coordination is clearly identified at low copper stoichiometry. In addition, EPR detectedcopper-copper interactions at full occupancy suggest that the octarepeat domain partially collapses, perhapsstabilizing this specific binding mode and facilitating cooperative copper uptake. This work provides thefirst complete characterization of all dominant copper coordination modes at pH 7.4.