Corentin BEDART

Research

Deciphering the mechanism of action of the P28GST in the treatment of autoimmune inflammatory disorders

The P28GST from Schistosoma haematobium, a parasite Glutathione S-Transferase, is a drug candidate in clinical evaluation for the treatment of inflammatory diseases, including inflammatory bowel diseases and Crohn's diseases. This protein combines two enzymatic activities, Glutathione S-Transferase (GST) and Prostaglandin D2 Synthase (PGDS), in addition to epitopic properties. If the use of P28GST in an inflammatory context orients the immune response towards an immunoregulatory and anti-inflammatory profile and confers a very important therapeutic potential in autoimmune inflammatory diseases, the mechanisms of action involved remain incompletely elucidated.This thesis contributes to the understanding of the mode of action of P28GST by studying its enzymatic activities at the atomic level using in silico approaches. The use of classical molecular dynamics allowed to study with accuracy the movements of the amino acids of the catalytic site, and their differential participation between the two activities. As classical techniques were not sufficient, metadynamics were performed to further investigate the participation of an essential tyrosine in the initiation of enzymatic activities, in particular via the determination of its free energy profile. Finally, the binding site of the specific ligand of the PGDS activity, the prostaglandin H2, was identified by molecular docking and classical molecular dynamics. These results allowed us to consider the search for specific inhibitors of PGDS activity, by directly targeting the identified binding site, by high throughput virtual screening and molecular docking techniques. Finally, the biological validation of the identified inhibitors has been initiated, with first results on GST activity and epitopic properties.This work required the development of numerous scripts in Python and R, allowing the processing and analysis of all the data generated. These different scripts led to the development of an analysis software and a visualization plugin, SINAPs (Structural Interaction Networks Analysis Protocols), to highlight the molecular interaction networks structuring proteins within molecular dynamics trajectories or crystallographic structures.