Covalent Stabilizers of the Interaction Between 14-3-3σand Estrogen Receptor-α

Selective stabilization of complexes formed by the hub protein 14-3-3 represents an emerging mechanism for the modulation of therapeutically relevant targets. In this letter, we describe a hit-finding campaign designed to identify small molecule stabilizers of the interaction between 14-3-3σ and the estrogen receptor alpha (ERα). Four structurally distinct hits were identified and validated using a combination of biochemical assays and biophysical techniques. Ternary complex crystal structures revealed that all four hit compounds form a covalent bond with Cys38 of 14-3-3σ via four different electrophilic warheads. Structure-based optimization of the most promising hit compound 9 led to dramatic improvements in stabilization activity and selectivity that exceeded the complex natural product fusicoccin A.