(608b) Chemically Diverse Peptide Libraries Yield Potent Inhibitors of the p53-MDM2 Interaction

Chemically stabilized peptides have attracted intense interest by academics and pharmaceutical companies due to their potential to hit currently ‘undruggable’ targets. However, engineering an optimal sequence, stabilizing linker location, and physicochemical properties is a slow and arduous process. By pairing non-natural amino acid incorporation and cell surface click chemistry in bacteria with high-throughput sorting, we developed a method to quantitatively select high affinity ligands and applied the SPEED (Stabilized Peptide Evolution by E. coli Display) technique to develop disrupters of the therapeutically relevant p53-MDM2 interaction.

We recently have expanded this method to include other linker molecules with a range of molecular properties, such as charge, lipophilicity, size, and rigidity. As applied to p53-based randomized peptide libraries, there was striking synergy between high affinity peptides’ amino acid sequence composition and linker identity. Specifically, we noted that different sequences have different linker preferences, and that linker choice and sequence are not independent.

Structural characterization, including circular dichroism spectroscopy and NMR elucidated linker and sequence contributions to binding. These data indicate that a one-size-fits-all approach is not compatible with generating potent binders, and that linker and sequence have to be jointly varied to achieve optimal binding properties.