A Robust Crystallographic Platform for High-Throughput β-Catenin Ligand Discovery

This study presents a robust crystallographic platform for assessing compounds binding to β-catenin. We developed a standardized protein production protocol for the armadillo domain of β-catenin (BC-ARM) and performed biophysical screens using Surface Plasmon Resonance (SPR) and Differential Scanning Fluorimetry (DSF). These findings led to the successful determination of the co-crystal structure of BC-ARM with compound 1 binding to previously reported site but distinct from known transcription factor binding sites. To broaden the search for novel BC binding sites, we utilized FragLites library with a cyclic peptide-stabilized BC-ARM construct. This yielded two high-resolution co-crystal structures identifying a previously unreported binding hotspot. Recognizing the limitations of the cyclic peptide-bound construct for general screening, we designed a novel, truncated BC-ARM construct. This new construct eliminates unstructured regions, reliably producing high-quality, diffracting crystals suitable for high-throughput crystallographic studies. In conclusion, the ligand-bound β-catenin structures and this novel, robust BC-ARM construct establish a powerful platform for further β-catenin investigation.