Pathology

Monomer

Organic chemistry

Disease

Amyloid β

Biology

Biophysics

Protein aggregation

Computational chemistry

Protein folding

Inorganic chemistry

Chemistry

Fibril

Amyloid (mycology)

Peptide

Oligomer

Amyloid fibril

Molecular dynamics

Polymer

Biochemistry

Medicine

Nature Chemistry

Oligomeric species populated during the aggregation of the Aβ42 peptide have been identified as potent cytotoxins linked to Alzheimer’s disease, but the fundamental molecular pathways that control their dynamics have yet to be elucidated. By developing a general approach that combines theory, experiment and simulation, we reveal, in molecular detail, the mechanisms of Aβ42 oligomer dynamics during amyloid fibril formation. Even though all mature amyloid fibrils must originate as oligomers, we found that most Aβ42 oligomers dissociate into their monomeric precursors without forming new fibrils. Only a minority of oligomers converts into fibrillar structures. Moreover, the heterogeneous ensemble of oligomeric species interconverts on timescales comparable to those of aggregation. Our results identify fundamentally new steps that could be targeted by therapeutic interventions designed to combat protein misfolding diseases.                                                                  Aβ42 oligomers are key toxic species associated with protein aggregation; however, the molecular pathways determining the dynamics of oligomer populations have remained unknown. Now, direct measurements of oligomer populations, coupled to theory and computer simulations, define and quantify the dynamics of Aβ42 oligomers formed during amyloid aggregation.

Dynamics of oligomer populations formed during the aggregation of Alzheimer’s Aβ42 peptide