Exploring the Potent Inhibition of CTP Synthase by Gemcitabine-5′-Triphosphate
| Autor: | Scott D. Taylor, Stephen L. Bearne, Samy Mohamady, Gregory D. McCluskey |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Cytidine Triphosphate viruses Metabolite Catabolite repression medicine.disease_cause Biochemistry Cytidine Diphosphate Structure-Activity Relationship 03 medical and health sciences chemistry.chemical_compound In vivo Escherichia coli medicine Carbon-Nitrogen Ligases heterocyclic compounds Enzyme Inhibitors Molecular Biology Dose-Response Relationship Drug Molecular Structure 030102 biochemistry & molecular biology Organic Chemistry Mutagenesis Cytidine 030104 developmental biology chemistry Cell culture Molecular Medicine Intracellular |
| Zdroj: | ChemBioChem. 17:2240-2249 |
| ISSN: | 1439-4227 |
| DOI: | 10.1002/cbic.201600405 |
| Popis: | CTP synthase (CTPS) catalyzes the conversion of UTP to CTP and is a target for the development of antiviral, anticancer, antiprotozoal, and immunosuppressive agents. Exposure of cell lines to the antineoplastic cytidine analogue gemcitabine causes depletion of intracellular CTP levels, but the direct inhibition of CTPS by its metabolite gemcitabine-5′-triphosphate (dF-dCTP) has not been demonstrated. We show that dF-dCTP is a potent competitive inhibitor of Escherichia coli CTPS with respect to UTP [Ki=(3.0±0.1) μm], and that its binding affinity exceeds that of CTP ≈75-fold. Site-directed mutagenesis studies indicated that Glu149 is an important binding determinant for both CTP and dF-dCTP. Comparison of the binding affinities of the 5′-triphosphates of 2′-fluoro-2′-deoxycytidine and 2′-fluoro-2′-deoxyarabinocytidine revealed that the 2′-F-arabino group contributes markedly to the strong binding of dF-dCTP. Geminal 2′-F substitution on UTP (dF-dUTP) did not result in an increase in binding affinity with CTPS. Remarkably, CTPS catalyzed the conversion of dF-dUTP into dF-dCTP, thus suggesting that dF-dCTP might be regenerated in vivo from its catabolite dF-dUTP. |
| Databáze: | OpenAIRE |
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