Protein misfolding and aggregation are common pathological features for many human diseases, such as Alzheimer’s disease, type 2 diabetes, amyotrophic lateral sclerosis and cancer. Aiming to increase the effectiveness of early drug discovery programs for these conditions, the lab of Dr. Georgios Skretas has developed a bacterial platform that enables the biosynthesis of molecular libraries with greatly expanded diversities and, contrary to affinity-based selection methods, their direct functional screening for discovering inhibitors of protein misfolding and aggregation.
In this system, large combinatorial libraries of macrocyclic peptides are biosynthesized in Escherichia coli cells and simultaneously screened for their ability to rescue pathogenic protein misfolding and aggregation using an ultrahigh-throughput flow cytometric screen. By using this technology, we have already identified hundreds of drug-like, head-to-tail cyclic peptides that modulate the aggregation and the associated cytotoxicity of the amyloid-β peptide (Aβ) and of mutant Cu/Zn superoxide dismutase (SOD1), both in vitro and in vivo (Matis et al., Nature Biomedical Engineering, 2017; Delivoria et al., Science Advances, 2019). Furthermore, we have described how this system can enable the rapid determination of structure-activity relationships and the definition of consensus motifs required for high bioactivity in these molecules.
Overall, this approach represents a straightforward strategy for the discovery and characterization of new molecular entities that rescue the misfolding of polypeptides known to be associated with disease effectively. These molecules are currently in pre-clinical development by ResQ Biotech, a spin-off company of the National Hellenic Research Foundation.