Ring-like N-fold Models of Aβ₄₂ fibrils

Area of Science:

• Neuroscience and molecular biology
• Protein misfolding and aggregation

Background:

• Amyloid-beta (Aβ) peptides, particularly Aβ42, are implicated in neurodegenerative diseases.
• Different Aβ isoforms exhibit distinct aggregation pathways and toxicity levels.

Purpose of the Study:

• To investigate the structural basis for the higher toxicity of Aβ42 compared to Aβ40.
• To model and analyze the pore-like structures formed by Aβ42.

Main Methods:

• Development of a scalable model for ring-like assemblies of S-shaped Aβ1-42 chains.
• Atomistic molecular dynamics simulations to study stability and structural properties.

Main Results:

• Aβ42 peptides can form S-shaped chains, enabling the assembly of pore-like structures not possible for Aβ40 (U-shaped).
• Simulated Aβ42 assemblies match the size and symmetry of experimentally observed structures.
• The interior pore of Aβ42 assemblies allows for water leakage.

Conclusions:

• The ability of Aβ42 to form S-shaped chains and subsequently pore-like structures is a key factor in its enhanced toxicity.
• Water leakage through Aβ42 amyloid pores presents a plausible mechanism for cellular toxicity.