An integrated bacterial system for the discovery of chemical rescuers of disease-associated protein misfolding

Abstract

Protein misfolding and aggregation are common pathological features of several human diseases, including Alzheimer's disease and type 2 diabetes. Here, we report an integrated and generalizable bacterial system for the facile discovery of chemical rescuers of disease-associated protein misfolding. In this system, large combinatorial libraries of macrocyclic molecules are biosynthesized in Escherichia coli cells and simultaneously screened for their ability to rescue pathogenic protein misfolding and aggregation using a flow cytometric assay. We demonstrate the effectiveness of this approach by identifying drug-like, head-to-tail cyclic peptides that modulate the aggregation of the Alzheimer's disease-associated amyloid β peptide. Biochemical, biophysical and biological assays using isolated amyloid β peptide, primary neurons and various established Alzheimer's disease nematode models showed that the selected macrocycles potently inhibit the formation of neurotoxic amyloid β peptide aggregates. We also applied the system to the identification of misfolding rescuers of mutant Cu/Zn superoxide dismutase-an enzyme linked with inherited forms of amyotrophic lateral sclerosis. Overall, the system enables the identification of molecules with therapeutic potential for rescuing the misfolding of disease-associated polypeptides.