Fibril Charge Affects α-Synuclein Hydrogel Rheological Properties

Area of Science:

• Biochemistry
• Materials Science
• Biophysics

Background:

• Alpha-synuclein is implicated in neurodegenerative diseases.
• Protein self-assembly into fibrils is key to amyloid formation.
• Understanding fibril interactions is crucial for controlling material properties.

Purpose of the Study:

• Investigate alpha-synuclein fibril interactions at varying pH.
• Determine the relationship between protein net charge, fibril interactions, and hydrogel properties.
• Explore conditions for alpha-synuclein hydrogel formation.

Main Methods:

• Rheology to measure gel stiffness.
• Small-angle X-ray scattering (SAXS) for structural analysis.
• Raman spectroscopy for molecular insights.
• Cryo-transmission electron microscopy (cryo-TEM) for ultrastructural visualization.

Main Results:

• Alpha-synuclein forms hydrogels at lower concentrations (50-300 μM) and wider pH range (6.0-7.5).
• Electrostatic stabilization observed at pH 6.0-7.5; precipitation at pH 5.5.
• Maximum gel stiffness (∼1300 Pa) at pH 6.5, driven by hydrophobic attraction between negatively charged fibrils.

Conclusions:

• Fibril-fibril interactions involve both electrostatic repulsion and hydrophobic attraction.
• Hydrophobic interactions enhance hydrogel density and stiffness.
• Findings offer insights into amyloid formation and potential applications.