Visualizing gaussian-chain like structural models of human α-synuclein in monomeric pre-fibrillar state: Solution...

Area of Science:

• Biophysics
• Structural Biology
• Neuroscience

Background:

• Alpha-synuclein is implicated in neurodegenerative diseases like Parkinson's.
• Understanding its monomeric state is crucial for disease mechanism insights.
• Monomeric alpha-synuclein is known to be intrinsically disordered.

Purpose of the Study:

• To visualize the conformational ensemble of monomeric alpha-synuclein in solution.
• To determine the structural characteristics of the prefibrillar monomeric state.
• To reconcile computational models with experimental scattering data.

Main Methods:

• Small-angle X-ray scattering (SAXS) data acquisition and analysis.
• Chain-ensemble modeling with dummy residues and Ensemble Optimization Method (EOM).
• All-atom model generation using AlphaFold2 and molecular dynamics simulations.

Main Results:

• Alpha-synuclein exhibits a disordered shape profile under non-associating conditions.
• Computational modeling identified two weighted clusters of semi-extended conformations.
• SAXS data integration with simulations refined models, favoring curved structures with low alpha-helical content.

Conclusions:

• The non-associating monomeric state of alpha-synuclein is best described by a dynamic equilibrium of curved conformations.
• These models possess minimal alpha-helical content, consistent with an intrinsically disordered nature.
• Integrated computational and experimental approaches provide a refined view of alpha-synuclein structure.