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J Biol Chem. 2007 Oct 26;282(43):31621-30. Epub 2007 Sep 4.

Cellular oligomerization of alpha-synuclein is determined by the interaction of oxidized catechols with a C-terminal sequence.

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  • 1Joseph Stokes Jr. Research Institute, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

Abstract

The mechanisms that govern the formation of alpha-synuclein (alpha-syn) aggregates are not well understood but are considered a central event in the pathogenesis of Parkinson's disease (PD). A critically important modulator of alpha-syn aggregation in vitro is dopamine and other catechols, which can prevent the formation of alpha-syn aggregates in cell-free and cellular model systems. Despite the profound importance of this interaction for the pathogenesis of PD, the processes by which catechols alter alpha-syn aggregation are unclear. Molecular and biochemical approaches were employed to evaluate the mechanism of catechol-alpha-syn interactions and the effect on inclusion formation. The data show that the intracellular inhibition of alpha-syn aggregation requires the oxidation of catechols and the specific noncovalent interaction of the oxidized catechols with residues (125)YEMPS(129) in the C-terminal region of the protein. Cell-free studies using novel near infrared fluorescence methodology for the detection of covalent protein-ortho-quinone adducts showed that although covalent modification of alpha-syn occurs, this does not affect alpha-syn fibril formation. In addition, oxidized catechols are unable to prevent both thermal and acid-induced protein aggregation as well as fibrils formed from a protein that lacks a YEMPS amino acid sequence, suggesting a specific effect for alpha-syn. These results suggest that inappropriate C-terminal cleavage of alpha-syn, which is known to occur in vivo in PD brain or a decline of intracellular catechol levels might affect disease progression, resulting in accelerated alpha-syn inclusion formation and dopaminergic neurodegeneration.

PMID:
17785456
DOI:
10.1074/jbc.M704737200
[PubMed - indexed for MEDLINE]
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