Megadalton-sized Dityrosine Aggregates of α-Synuclein Retain High Degrees of Structural Disorder and Internal Dynamics.

Journal of Molecular Biology
S. VerziniPhilipp Selenko

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 αS...Continue Reading

Methods Mentioned

BETA
nuclear
dynamic
circular
transmission electron microscopy
electrophoresis
AFM
size-exclusion chromatography
Atomic
NMR
GTPase

Software Mentioned

MaxQuant
TOPSPIN
Malvern DTS
PICUP
xiNET
iNMR
Xi
CCPNmr

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Alpha-synucleins are small proteins that are believed to restrict the mobility of synpatic vesicles and inhibit neurotransmitter release. Aggregation of these proteins have been linked to several types of neurodegenerative diseases including dementia with Lewy bodies and Parkinson's disease. Here is the latest research on α-synuclein aggregation.