The structural heterogeneity of α-synuclein is governed by several distinct subpopulations with interconversion times slower than milliseconds

• Published in: Structure (London) 2021-09, Vol.29 (9), p.1048-1064.e6
• Main Authors: Chen, Jiaxing, Zaer, Sofia, Drori, Paz, Zamel, Joanna, Joron, Khalil, Kalisman, Nir, Lerner, Eitan, Dokholyan, Nikolay V.
• Format: Article
• Language: English
• Subjects: alpha-Synuclein - chemistry; conformational ensemble; discrete molecular dynamics simulations; Fluorescence Resonance Energy Transfer; Humans; intrinsically disordered protein; Molecular Dynamics Simulation; neurodegenerative diseases; α-synuclein
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2021.05.002

α-Synuclein plays an important role in synaptic functions by interacting with synaptic vesicle membrane, while its oligomers and fibrils are associated with several neurodegenerative diseases. The specific monomer structures that promote its membrane binding and self-association remain elusive due to its transient nature as an intrinsically disordered protein. Here, we use inter-dye distance distributions from bulk time-resolved Förster resonance energy transfer as restraints in discrete molecular dynamics simulations to map the conformational space of the α-synuclein monomer. We further confirm the generated conformational ensemble in orthogonal experiments utilizing far-UV circular dichroism and cross-linking mass spectrometry. Single-molecule protein-induced fluorescence enhancement measurements show that within this conformational ensemble, some of the conformations of α-synuclein are surprisingly stable, exhibiting conformational transitions slower than milliseconds. Our comprehensive analysis of the conformational ensemble reveals essential structural properties and potential conformations that promote its various functions in membrane interaction or oligomer and fibril formation. [Display omitted] •trFRET-guided DMD simulations are used to study α-synuclein monomer conformations•Multifunctions of α-synuclein are explained by its monomeric structures•Millisecond conformational dynamics of α-synuclein monomer is discovered by smPIFE Structures of intrinsically disordered proteins (IDPs) are difficult to study by traditional biophysical methods. Chen et al. developed a new methodology to characterize the ensemble structure of an IDP, α-synuclein. Distinct structural subpopulations of α-synuclein monomer with stable local structures might promote its physiological and pathogenic functions.