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Cu K-edge X-ray absorption spectroscopy reveals differential copper coordination within amyloid-? oligomers compared to amyloid-? monomers.

ABSTRACT: The fatal neurological disorder Alzheimer's disease has been linked to soluble neurotoxic oligomers of amyloid-? (A?) peptides. Herein we demonstrate that Cu(1+) ligated within A?(42) oligomers (A? sequence: DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA) possesses a highly dioxygen sensitive tetrahedral coordination geometry. The biological implications of these findings are discussed.

SUBMITTER: Shearer J

PROVIDER: S-EPMC3082590 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Cu K-edge X-ray absorption spectroscopy reveals differential copper coordination within amyloid-β oligomers compared to amyloid-β monomers.

Shearer Jason J Callan Paige E PE Tran Thao T Szalai Veronika A VA

Chemical communications (Cambridge, England) 20101108 48

The fatal neurological disorder Alzheimer's disease has been linked to soluble neurotoxic oligomers of amyloid-β (Aβ) peptides. Herein we demonstrate that Cu(1+) ligated within Aβ(42) oligomers (Aβ sequence: DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA) possesses a highly dioxygen sensitive tetrahedral coordination geometry. The biological implications of these findings are discussed. ...[more]

PMID: 21060917

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Project description:Beta-2-microglobulin (beta2m) deposits as amyloid fibrils in the musculoskeletal system of patients undergoing long-term dialysis treatment as a result of kidney failure. Previous work has shown that Cu(II) binding causes beta2m to organize into nativelike dimers and tetramers that precede amyloid formation. Cu(II) is then released from higher-order oligomers before mature Cu(II)-free amyloid fibrils are formed. While some of the Cu(II)-induced structural changes that enable beta2m self-assembly are starting to be revealed, the details of how the Cu(II) binding site evolves from the monomer to the dimers and tetramers are not known. Here, we report results from three mass spectrometry (MS)-based methods that provide insight into the changing Cu-beta2m interactions. We find that monomeric beta2m binds Cu(II) via the N-terminal amine, the amide of Gln2, His31, and Asp59. In the dimer and tetramer, Asp59 is no longer bound to Cu(II), but the other residues still comprise a well-defined albeit weaker binding site that is better able to release Cu(II). Consistent with this is the observation that a fraction of the tetrameric species no longer binds Cu(II) at this weakened binding site, which agrees with a previous report that suggested the tetramer as the first Cu(II)-free oligomer. Our results also provide some insight into structural changes caused by Cu(II) binding that facilitate oligomer formation. Specifically, binding by Asp59 in the monomer requires significant movement of this residue, and we propose that this repositioning is important for establishing a pair of dimer-stabilizing salt bridges between this residue and Lys19. We also find evidence that Cu(II) binding in the N-terminal region of the monomer repels Arg3, which likely allows this residue to form a pair of dimer-stabilizing salt bridges with Glu16. Overall, our measurements suggest that the previously proposed conformational switch caused by Cu(II) binding includes not only a cis-trans isomerization at Pro32 but also the repositioning of residues that are critical for the formation of new electrostatic interactions.

Dataset Information

Cu K-edge X-ray absorption spectroscopy reveals differential copper coordination within amyloid-? oligomers compared to amyloid-? monomers.

Publications

Cu K-edge X-ray absorption spectroscopy reveals differential copper coordination within amyloid-β oligomers compared to amyloid-β monomers.

Similar Datasets

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