The dynamic structure of α-synuclein multimers

Area of Science:

• Biochemistry
• Structural Biology
• Neuroscience

Background:

• Alpha-synuclein aggregation is central to Parkinson's disease pathogenesis.
• Monomeric alpha-synuclein is intrinsically disordered, but can form soluble multimers in vivo.
• Contradictory findings exist regarding helical versus beta-strand rich alpha-synuclein species.

Purpose of the Study:

• To investigate the diverse multimeric states of alpha-synuclein.
• To reconcile conflicting observations on alpha-synuclein structure in cellular environments.
• To understand the role of different alpha-synuclein conformations in aggregation.

Main Methods:

• Generation of an alpha-synuclein construct with an N-terminal extension.
• Utilized Nuclear Magnetic Resonance (NMR) chemical shifts.
• Employed residual dipolar couplings (RDCs) to guide ensemble construction.

Main Results:

• The dominant state observed is a disordered monomer.
• A small fraction of helical trimers and tetramers were detected.
• Trimeric and tetrameric oligomers rich in beta-strand content were also identified.
• The ensemble provides a structural basis for both helical and beta-strand forms.

Conclusions:

• The findings reconcile the presence of both disordered monomers and helical tetramers in cells.
• Helical tetramers may act as a storage form of alpha-synuclein at high concentrations.
• This storage mechanism could prevent aggregation of non-membrane-bound monomers.
• Understanding these states is crucial for Parkinson's disease research.