Megadalton-sized Dityrosine Aggregates of α-Synuclein Retain High Degrees of Structural Disorder and Internal Dynamics. Issue 24 (4th December 2020)

• Record Type: Journal Article
• Authors: Verzini, Silvia; Shah, Maliha; Theillet, Francois-Xavier; Belsom, Adam; Bieschke, Jan; Wanker, Erich E.; Rappsilber, Juri; Binolfi, Andres; Selenko, Philipp
• Is Part Of: Journal of molecular biology. Volume 432:Issue 24(2020)
• Publication Date: 2020-12-04
• Subjects: amyloid proteins -- neurodegenerative disease -- protein aggregation -- structural disorder -- protein dynamics; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2020.10.023
• Languages: English
• ISSNs: 0022-2836

Abstract

Graphical abstract: Highlights: Despite their large size, αSyn dityrosine aggregates are dynamic and disordered. αSyn dityrosine aggregates specifically form in complex environments. αSyn dityrosine aggregates retain residual membrane binding activity. Dityrosine aggregates inhibit amyloid formation of monomeric αSyn. αSyn dityrosine aggregates are not cytotoxic. Abstract: Heterogeneous aggregates of the human protein α-synuclein (αSyn) are abundantly found in Lewy body inclusions of Parkinson's disease patients. While structural information on classical αSyn amyloid fibrils is available, little is known about the conformational properties of disease-relevant, non-canonical aggregates. Here, we analyze the structural and dynamic properties of megadalton-sized dityrosine adducts of αSyn that form in the presence of reactive oxygen species and cytochrome c, a proapoptotic peroxidase that is released from mitochondria during sustained oxidative stress. In contrast to canonical cross-β amyloids, these aggregates retain high degrees of internal dynamics, which enables their characterization by solution-state NMR spectroscopy. We find that intermolecular dityrosine crosslinks restrict αSyn motions only locally whereas large segments of concatenated molecules remain flexible and disordered. Indistinguishable aggregates form in crowded in vitro solutions and in complex environments of mammalian cell lysates, where relative amounts of free reactive oxygen species, rather than cytochrome c, are rate limiting. We further establish that dityrosine adducts inhibit classical amyloid formation by maintaining αSyn in its monomeric form and that they are non-cytotoxic despite retaining basic membrane-binding properties. Our results suggest that oxidative αSyn aggregation scavenges cytochrome c 's activity into the formation of amorphous, high molecular-weight structures that may contribute to the structural diversity of Lewy body deposits.