Structures of soluble amyloid oligomers from computer simulations.

Area of Science:

• Biochemistry
• Structural Biology
• Computational Chemistry

Background:

• Neurodegenerative diseases like Alzheimer's and Parkinson's are linked to protein misfolding and amyloid fibril formation.
• Early-stage soluble oligomers are cytotoxic, but their structures are difficult to determine experimentally.
• Understanding fibrillogenesis is key to developing therapeutic strategies.

Purpose of the Study:

• To investigate the aggregation pathways of the shortest amyloid-forming peptide using computational simulations.
• To characterize the structural diversity of early-stage amyloid oligomers.
• To elucidate the mechanisms of nucleus formation in fibrillogenesis.

Main Methods:

• Utilized an activated method with a reduced atomic representation for molecular simulations.
• Simulated the aggregation of seven chains of a short amyloid-forming peptide (KFFE).
• Analyzed the resulting oligomeric structures and their energy landscapes.

Main Results:

• Identified three distinct, low-energy topologies for aggregated KFFE monomers: amorphous oligomers, beta-barrel-like rings, and cross-beta-sheet structures.
• Observed pathways from misfolded aggregates to fibrillar structures.
• Highlighted the variety of building blocks contributing to the critical nucleus for fibril growth.

Conclusions:

• The aggregation process can yield multiple structural outcomes with similar stability.
• Computational modeling provides insights into the complex pathways of amyloid formation.
• These findings contribute to understanding the structural basis of neurodegenerative diseases.