Fragment screening using biolayer interferometry reveals ligands targeting the SHP-motif binding site of the AAA+ ATPase p97

Biosensor techniques have become increasingly important for fragment-based drug discovery during the last years. The AAA+ ATPase p97 is an essential protein with key roles in protein homeostasis and a possible target for cancer chemotherapy. Currently available p97 inhibitors address its ATPase activity and globally impair p97-mediated processes. In contrast, inhibition of cofactor binding to the N-domain by a protein-protein-interaction inhibitor would enable the selective targeting of specific p97 functions. Here, we describe a biolayer interferometry-based fragment screen targeting the N-domain of p97 and demonstrate that a region known as SHP-motif binding site can be targeted with small molecules. Guided by molecular dynamics simulations, the binding sites of selected screening hits were postulated and experimentally validated using protein- and ligand-based NMR techniques, as well as X-ray crystallography, ultimately resulting in the first structure of a small molecule in complex with the N-domain of p97. The identified fragments provide insights into how this region could be targeted and present first chemical starting points for the development of a protein-protein interaction inhibitor preventing the binding of selected cofactors to p97.

Here we publish the primary data of the biolayer-interferometry (BLI), STD-NMR, HSQC-NMR and mixed-solvent MD simulation results.
For BLI, the sensorgrams of 10 binding fragments identified in the screening are given. Measurements were conducted with the N-domain and the ND1-construct of p97. Additionaly, the measurements with ADP as positive control (n=6) are provided.
Four of the 10 fragments were selected as most promising hits for further investigation: TROLL2, TROLL7, TROLL8 and TROLL12. For these fragemnts, the STD-NMR build-up data, the HSQC-NMR spectra and the representative poses from the mixed solvent MD simulations used for CORCEMA predictions are provided. For TROLL2 the anomalous map of the bromine atom of the crystal structure (PDB entry: 7PUX) is given.