Molecular docking studies of salubrinal and its analogs as inhibitors of the GADD34:PP1 enzyme

The phenomenon of the endoplasmic reticulum (ER) stress as a molecular pathophysiological process underlies diseases as cancer, diabetes mellitus, myocardial infarction, neurodegenerative disorders, diseases of the urinary system, disorders associated with bone integrity, etc. To prevent ER stress, salubrinal, which is a phosphatase inhibitor of the eukaryotic translation initiation factor - GADD34:PP1, is currently being intensively studied. The aim of this work is to search for new analogues of this drug using molecular docking methods. Optimization of the geometry of the studied structures and molecular docking was carried out using the ArgusLab 4.0.1 software package. The three-dimensional crystal structure of the GADD34:PP1 enzyme (PDB ID: 4XPN) was loaded in the PDB format from the protein molecule data bank. The model of the binding site was created on the basis of the phosphoric acid residue (403 PO4). The dimensions of the binding site were set manually and were 40.000 angstrom along the X-axis, 40.000 angstrom - the Y-axis and 40.000 angstrom - the Z-axis. The docking was done with a flexible ligand, and the semi-empirical AScore function was used for the scoring procedure. It was shown that for the salubrinal molecule the most favorable was the conformation stabilized by the intramolecular hydrogen bond formed between the hydrogen atom of the thiourea fragment and the oxygen atom of the amide fragment. According to molecular docking data, six compounds from the fifty-four analyzed analogues of salubrinal exceed it in the stability of the complex formed with GADD34:PP1. The results of this work can be used to create new phosphatase inhibitors of the eukaryotic translation initiation factor GADD34:PP1.