Structural basis for α-helix mimicry and inhibition of protein-protein interactions with oligourea foldamers.

Efficient optimization of a peptide lead into a drug candidate frequently needs further transformation to augment properties such as bioavailability. Among the different options, foldamers, sequence-based oligomers with precise folded conformation, have emerged as a promising technology. Here, we introduce oligourea foldamers to reduce the peptide character of inhibitors of protein-protein interactions (PPI). However, the precise design of such mimics is currently limited by the lack of structural information on how these foldamers adapt to protein surfaces. We now report a collection of X-ray structures of peptide-oligourea hybrids in complex with ubiquitin ligase MDM2 and vitamin D receptor and show how such hybrid oligomers can be designed to bind with high affinity to protein targets. This work should enable the generation of more effective foldamer-based disruptors of PPIs in the context of peptide lead optimization.