Rapid exchange of metal between Zn7-metallothionein-3 and amyloid-β peptide promotes amyloid-related structural changes

Jeppe Trudslev Pedersen, Christelle Hureau, Lars Bo Stegeager Hemmingsen, Niels H. H. Heegaard, Jesper Østergaard, Milan Vasák, Peter Faller

    54 Citationer (Scopus)

    Abstract

    Metal ions, especially Zn 2+ and Cu 2+, are implemented in the neuropathogenesis of Alzheimer's disease (AD) by modulating the aggregation of amyloid-β peptides (Aβ). Also, Cu 2+ may promote AD neurotoxicity through production of reactive oxygen species (ROS). Impaired metal ion homeostasis is most likely the underlying cause of aberrant metal-Aβ interaction. Thus, focusing on the body's natural protective mechanisms is an attractive therapeutic strategy for AD. The metalloprotein metallothionein-3 (MT-3) prevents Cu-Aβ-mediated cytotoxicity by a Zn-Cu exchange that terminates ROS production. Key questions about the metal exchange mechanisms remain unanswered, e.g., whether an Aβ-metal-MT-3 complex is formed. We studied the exchange of metal between Aβ and Zn 7-MT-3 by a combination of spectroscopy (absorption, fluorescence, thioflavin T assay, and nuclear magnetic resonance) and transmission electron microscopy. We found that the metal exchange occurs via free Cu 2+ and that an Aβ-metal-MT-3 complex is not formed. This means that the metal exchange does not require specific recognition between Aβ and Zn 7-MT-3. Also, we found that the metal exchange caused amyloid-related structural and morphological changes in the resulting Zn-Aβ aggregates. A detailed model of the metal exchange mechanism is presented. This model could potentially be important in developing therapeutics with metal-protein attenuating properties in AD.

    OriginalsprogEngelsk
    TidsskriftBiochemistry
    Vol/bind51
    Udgave nummer8
    Sider (fra-til)1697-1706
    ISSN0006-2960
    DOI
    StatusUdgivet - 28 feb. 2012

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