Liquid condensates increase potency of amyloid fibril inhibitors

In living cells, liquid condensates form in the cytoplasm and nucleoplasm via phase separation and regulate physiological processes. They also regulate aberrant aggregation of amyloid fibrils, a process linked to Alzheimer's and Parkinson's diseases. In the absence of condensates it has been shown that amyloid aggregation can be inhibited by molecular chaperones and rationally designed drugs. However it remains unknown how this drug- or chaperone-mediated inhibition of amyloid fibril aggregation is affected by phase-separated condensates. Here we study the interplay between protein aggregation, its inhibition and liquid-liquid phase separation. Our key finding is that the potency of inhibitors of amyloid formation can be strongly enhanced. We show that the corresponding mechanism relies on the colocalization of inhibitors and aggregates inside the liquid condensate. We provide experimentally testable physicochemical conditions under which the increase of inhibitor potency is most pronounced. Our work highlights the role of spatio-temporal heterogeneity in curtailing aberrant protein aggregation and suggests design principles for amyloid inhibitors accounting for partitioning of drugs into liquid condensates.