Amphipathic helical peptides hamper protein-protein interactions of the intrinsically disordered chromatin nuclear protein 1 (NUPR1)

Methods: We explored how amphipathic helical-designed peptides were capable of interacting with wild-type NUPR1 and the Thr68Gln mutant, inhibiting the interaction with NUPR1 protein partners. We used in vitro biophysical techniques (fluorescence, circular dichroism (CD), nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC)), in silico studies (docking and molecular dynamics (MD)), and in cellulo protein ligation assays (PLAs) to study the interaction.

Background: NUPR1 is a multifunctional intrinsically disordered protein (IDP) involved, among other functions, in chromatin remodelling, and development of pancreatic ductal adenocarcinoma (PDAC). It interacts with several biomolecules through hydrophobic patches around residues A1a33 and Thr68. The drug trifluoperazine (TFP), which hampers PDAC development in xenografted mice, also binds to those regions. Because of the large size of the hot-spot interface of NUPR1, small molecules could not be adequate to modulate its functions.