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Development of Synthetic Copper(I) Transmembrane Transporters and their Biological Applications

par Renier, Nathan
Président du jury Bartik, Kristin
Promoteur Valkenier, Hennie
Publication Non publié, 2023-02-17

Thèse de doctorat

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Résumé :

The development of synthetic molecules able to transport ions through lipid bilayer membranes is of growing interest in the field of supramolecular chemistry. The balance of anions and cations has an important role in the biology of all living organisms. This thesis will focus on the development of copper(I) transporters, the methodologies developed to study them, and their biological applications. The first part of this thesis is focused on the development of copper(I) transmembrane transporters and the methodology required for their study. These transporters were developed for a potential therapeutic application, with the idea that synthetic copper(I) transporters could replace dysfunctional copper(I) transport proteins, which are responsible for distributing copper(I) within cells. Dysfunction of these proteins is the cause of Wilson and Menkes diseases.Calix4arene functionalised with two imidazole groups can strongly bind copper(I) through a linear coordination motif. This ability and their high lipophilicity made them good candidates to transport copper(I) through bilayer membranes. For that, a new assay was developed using liposomes as model systems for membranes, in which a phenanthroline based copper(I) sensitive dye is encapsulated. The changes in fluorescence as monitored by spectroscopy allowed for the observation of copper(I) transport. Most of these results are reported in the publication: “Transmembrane transport of copper(I) by imidazole-functionalised calix[4]arenes” N. Renier, O. Reinaud, I. Jabin, and H. Valkenier. Chem. Commun., 2020, 56, 8206-8209. The improvement and limitations of the transport assay are also described. In the second part, the development of a deliverable copper(I) transporter is described along with the biological effects of the compound on various biological systems. A new transporter was synthesised and shown to be able to reach liposomes membrane when added from an organic solution or from other liposomes, which was not the case for the more lipophilic, previous generation of transporters. In collaboration with chemical biologists, the ability of this new transporter to restore copper transport in genetically modified yeast cells, lacking copper(I) transporters, was demonstrated by following their growth in an environment in which non treated cells could not survive. Additionally, the toxicity of transporters against pathogenic bacteria was evaluated. When supplemented with copper, transporters showed a high toxicity against various resistant gram+ and gram- bacteria. Furthermore, the ability of bacteria to develop resistance against this new antibiotic was studied and showed that MRSA could not find resistance pathways whereas E.coli could. The antibiotic was shown to be as efficient for biofilms as for planktonic bacteria.Finally, in the context of the development of new anticancer agents based on synthetic copper(I) transporters and in collaboration with biochemists, a structure-activity relationship study was carried out and multiple variations to the chemical structure of the deliverable copper(I) transporter were explored to try to increase their toxicity. Along with the synthesis, the binding and transport properties of these new structures were studied and compared to their toxicity. The results obtained in this study are paving the way for future development of antibiotics and anti-cancer agents using a novel strategy of perturbing pathogenic cells with synthetic copper(I) transporters.