Ponzini, E, De Palma, A, Cerboni, L et al. (10 more authors) (2019) Methionine oxidation in α-synuclein inhibits its propensity for ordered secondary structure. The Journal of Biological Chemistry, 294 (14). pp. 5657-5665. ISSN 0021-9258
Abstract
α-Synuclein (AS) is an intrinsically disordered protein highly expressed in dopaminergic neurons. Its amyloid aggregates are the major component of Lewy bodies, a hallmark of Parkinson's disease (PD). AS is particularly exposed to oxidation of its methionine residues, both in vivo and in vitro. Oxidative stress has been implicated in PD and oxidized α-synuclein has been shown to assemble into soluble, toxic oligomers, rather than amyloid fibrils. However, the structural effects of methionine oxidation are still poorly understood. In this work, oxidized AS was obtained by prolonged incubations with dopamine (DA) or epigallocatechin-3-gallate (EGCG), two inhibitors of AS aggregation, indicating that EGCG promotes the same final oxidation product as DA. The conformational transitions of the oxidized and non-oxidized protein were monitored by complementary biophysical techniques, including MS, ion mobility (IM), CD and FTIR spectroscopy assays. Although the two variants displayed very similar structures under conditions that stabilize highly disordered or highly ordered states, differences emerged in the intermediate points of transitions induced by organic solvents, such as trifluoroethanol (TFE) and methanol (MeOH), indicating a lower propensity of the oxidized protein for forming either α- or β-type secondary structure. Furthermore, oxidized AS displayed restricted secondary-structure transitions in response to dehydration and slightly amplified tertiary-structure transitions induced by ligand binding. This difference in susceptibility to induced folding could explain the loss of fibrillation potential observed for oxidized AS.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article is protected by copyright. This is an author produced version of a paper published in the Journal of Biological Chemistry. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Molecular and Cellular Biology (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 05 Mar 2019 14:26 |
Last Modified: | 15 Apr 2019 08:40 |
Status: | Published |
Publisher: | American Society for Biochemistry and Molecular Biology |
Identification Number: | 10.1074/jbc.ra118.001907 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:143239 |