Byrd, E.J., Rowlinson, B., Crossley, J.A. et al. (4 more authors) (2025) Zn2+ Binding Shifts the Conformational Ensemble of α-Synuclein Monomers toward Accelerated Amyloid Formation. Journal of the American Chemical Society, 147 (40). pp. 36464-36477. ISSN: 0002-7863
Abstract
Alpha-synuclein (αS) is an intrinsically disordered protein (IDP) that can self-assemble into amyloid fibrils, undergoing a transition from disordered monomers to ordered β-sheet-rich fibrils. The amyloid state of αS is implicated in various synucleinopathies, most notably Parkinson's disease (PD), in which αS fibrils accumulate as insoluble Lewy body deposits. Colocalized with αS in Lewy bodies are elevated levels of metal ions including Zn<sup>2+</sup>. We find <i>in vitro</i> that Zn<sup>2+</sup> accelerates aggregation of N-terminally acetylated αS, decreasing the <i>t</i><sub>50</sub> ca. 5-fold, as measured by thioflavin T (ThT) fluorescence. Strikingly, the extent of Zn<sup>2+</sup> binding (native mass spectrometry; MS) and shifts of the monomeric αS conformational ensemble toward compaction, measured using ion mobility MS (IM-MS) at different αS:Zn<sup>2+</sup> ratios, mirror precisely the accelerated aggregation kinetics. Chemical shift perturbations in Nuclear Magnetic Resonance (NMR) spectroscopy were investigated together with molecular dynamics (MD) to map the Zn<sup>2+</sup> binding sites and subsequent effects on conformation under identical solution conditions to those used in IM-MS. Zn<sup>2+</sup> is found to predominantly interact with negative residues in the C-terminal region of αS but also His50 in the N-terminal region. This promiscuity in interactions potentially guides compaction of the protein chain by bridging residues between the N- and C-terminal regions through Zn<sup>2+</sup> ion co-ordination. This study provides insights into the early stages of amyloid assembly, correlating aggregation kinetics with structural compaction in monomeric αS and highlighting the capability of native IM-MS to resolve complex structural ensembles of a disordered protein.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2025 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. |
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) |
Date Deposited: | 08 Oct 2025 13:40 |
Last Modified: | 08 Oct 2025 13:40 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/jacs.5c11056 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:232543 |