Phosphorylation modifies the molecular stability of beta-amyloid deposits

Protein aggregation plays a crucial role in neurodegenerative diseases. A key feature of protein aggregates is their ubiquitous modification by phosphorylation. Little is known, however, about the molecular consequences of phosphorylation of protein aggregates. Here we show that phosphorylation of beta-amyloid at serine 8 increases the stability of its pathogenic aggregates against high-pressure and SDS-induced dissociation. We further demonstrate that phosphorylation results in an elevated number of hydrogen bonds at the N terminus of beta-amyloid, the region that is critically regulated by a variety of post-translational modifications. Because of the increased lifetime of phosphorylated beta-amyloid aggregates, phosphorylation can promote the spreading of beta-amyloid in Alzheimer pathogenesis. Our study suggests that regulation of the molecular stability of protein aggregates by post-translational modifications is a crucial factor for disease progression in the brain.