Coarse-grained models for protein aggregation.

The aggregation of soluble proteins into fibrillar species is a complex process that spans many lengths and time scales, and that involves the formation of numerous on-pathway and off-pathway intermediate species. Despite this complexity, several elements underlying the aggregation process appear to be universal. The kinetics typically follows a nucleation-growth process, and proteins with very different sequences aggregate to form similar fibril structures, populating intermediates with sufficient structural similarity to bind to a common antibody. This review focuses on a computational approach that exploits the common features of aggregation to simplify or 'coarse-grain' the representation of the protein. We highlight recent developments in coarse-grained modeling and illustrate how these models have been able to shed new light into the mechanisms of protein aggregation and the nature of aggregation intermediates. The roles of aggregation prone conformations in the monomeric state and the influence of inherent β-sheet and aggregation propensities in modulating aggregation pathways are discussed.