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Études structurales de ligands peptidomimétiques de TRAIL complexés au récepteur de mort DR5

Abstract : Apoptosis plays a protective role against the formation of tumor cells. This phenomenon can be regulated by the death receptor pathway, among which the Death Receptor 5 that can be activated by the TRAIL ligand (Tumor necrosis factor-Related Apoptosis Induction Ligand), whose major interest is to induce tumor cell apoptosis, specifically. Our work focuses on peptidomimetic ligands of TRAIL: those 16 amino acid peptides exist as monomers or multimers and show affinity for DR5 protein as up to 5-fold the affinity of TRAIL. Functional assays have shown that not only those ligands induce in vitro apoptosis of tumor cells, but also show selectivity for cancer cells, and can reduce mice tumor volume in vivo. The purpose of this project is to characterize the mechanisms by which those ligands interact with DR5, by using Nuclear Magnetic Resonance (NMR) and X-Ray Crystallography. We have produced the recombinant extracellular domain of DR5 in fusion with the NusA protein, in order to increase the folding of the protein, and we have purified the receptor through a 4-step protocol. We assigned the backbone resonances of 89 % of the protein residues with NMR, and secondary structure calculations showed that DR5 adopts the same β strand folding in solution as from the DR5 crystal structures from the PDB (Protein Data Bank). NMR titrations of DR5 with monomeric and multimeric ligands have allowed us to identify the peptide-protein binding area within the first Cystein Rich Domain (CRD1) of the receptor, but also that the binding with oligomeric peptides lead to protein-protein interactions at the level of the CRD2, suggesting the dimerization of the receptor. This was confirmed par Size Exclusion Chromatography assays that showed an oligomerization of the receptor in the presence of dimeric and trimeric peptides. Ongoing crystallography assays are conducted in order to determine the 3D structure at the atomic level of oligomeric complexes with DR5. Our results show that peptidomimetic ligands of TRAIL display a different mechanism from TRAIL in the activation of apoptosis.
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Submitted on : Friday, May 3, 2019 - 10:08:55 AM
Last modification on : Thursday, March 5, 2020 - 3:26:34 PM


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  • HAL Id : tel-02118495, version 1



Antoine Baudin. Études structurales de ligands peptidomimétiques de TRAIL complexés au récepteur de mort DR5. Chimie théorique et/ou physique. Université de Bordeaux, 2018. Français. ⟨NNT : 2018BORD0424⟩. ⟨tel-02118495⟩



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