Set-up and screening of a fragment library targeting the 14-3-3 protein interface† †Electronic supplementary information (ESI) available: Statistical analysis of the fragment collection, DSF melting curves, DSF compound-induced thermal shifts, WaterLOGSY NMR spectra, 1H–15N TROSY-HSQC NMR spectra and chemical shift perturbation plots. See DOI: 10.1039/c9md00215d

Fragment-based driven discovery of 3 new low molecular weight starting points for the modulation of 14-3-3 protein–protein interactions. Protein–protein interactions (PPIs) are at the core of regulation mechanisms in biological systems and consequently became an attractive target for therapeutic intervention. PPIs involving the adapter protein 14-3-3 are representative examples given the broad range of partner proteins forming a complex with one of its seven human isoforms. Given the challenges represented by the nature of these interactions, fragment-based approaches offer a valid alternative for the development of PPI modulators. After having assembled a fragment set tailored on PPIs' modulation, we started a screening campaign on the sigma isoform of 14-3-3 adapter proteins. Through the use of both mono- and bi-dimensional nuclear magnetic resonance spectroscopy measurements, coupled with differential scanning fluorimetry, three fragment hits were identified. These molecules bind the protein at two different regions distant from the usual binding groove highlighting new possibilities for selective modulation of 14-3-3 complexes.