Saturday, September 9, 2023

Structure-Based Optimization of Covalent, Small-Molecule Stabilizers of the 14-3-3σ/ERα Protein–Protein Interaction from Nonselective Fragments

Markella Konstantinidou, Emira J. Visser, Edmee Vandenboorn, Sheng Chen, Priyadarshini Jaishankar, Maurits Overmans, Shubhankar Dutta, R. Jeffrey Neitz, Adam R. Renslo, Christian Ottmann, Luc Brunsveld, and Michelle R. Arkin

Journal of the American Chemical Society 2023

DOI: 10.1021/jacs.3c05161

The stabilization of protein–protein interactions (PPIs) has emerged as a promising strategy in chemical biology and drug discovery. The identification of suitable starting points for stabilizing native PPIs and their subsequent elaboration into selective and potent molecular glues lacks structure-guided optimization strategies. We have previously identified a disulfide fragment that stabilized the hub protein 14-3-3σ bound to several of its clients, including ERα and C-RAF. Here, we show the structure-based optimization of the nonselective fragment toward selective and highly potent small-molecule stabilizers of the 14-3-3σ/ERα complex. The more elaborated molecular glues, for example, show no stabilization of 14-3-3σ/C-RAF up to 150 μM compound. Orthogonal biophysical assays, including mass spectrometry and fluorescence anisotropy, were used to establish structure–activity relationships. The binding modes of 37 compounds were elucidated with X-ray crystallography, which further assisted the concomitant structure-guided optimization. By targeting specific amino acids in the 14-3-3σ/ERα interface and locking the conformation with a spirocycle, the optimized covalent stabilizer 181 achieved potency, cooperativity, and selectivity similar to the natural product Fusicoccin-A. This case study showcases the value of addressing the structure, kinetics, and cooperativity for molecular glue development.



Rapid, potent, and persistent covalent chemical probes to deconvolute PI3Kα signaling

Lukas Bissegger,  Theodora A. Constantin,  Erhan Keles,  Luka Raguž,   Isobel Barlow-Busch,  Clara Orbegozo,   Thorsten Schaefer,  Valentina...