ATP Generation in the Trypanosoma brucei Procyclic Form
| Autor: | Pierre Voisin, Frédéric Bringaud, Virginie Coustou, Véronique Bouchaud, Marc Biran, Théo Baltz, Philippe Diolez, Paul Canioni, Sébastien Besteiro, Paul A.M. Michels |
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| Rok vydání: | 2003 |
| Předmět: |
Oligomycin
ATP synthase Cell Biology Oxidative phosphorylation Biology Trypanosoma brucei biology.organism_classification Biochemistry chemistry.chemical_compound Pyruvate phosphate dikinase Substrate-level phosphorylation chemistry biology.protein Molecular Biology Adenosine triphosphate Pyruvate kinase |
| Zdroj: | Journal of Biological Chemistry. 278:49625-49635 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m307872200 |
| Popis: | Trypanosoma brucei is a parasitic protist responsible for sleeping sickness in humans. The procyclic form of this parasite, transmitted by tsetse flies, is considered to be dependent on oxidative phosphorylation for ATP production. Indeed, its respiration was 55% inhibited by oligomycin, which is the most specific inhibitor of the mitochondrial F0/F1-ATP synthase. However, a 10-fold excess of this compound did not significantly affect the intracellular ATP concentration and the doubling time of the parasite was only 1.5-fold increased, suggesting that oxidative phosphorylation is not essential for procyclic trypanosomes. To further investigate the sites of ATP production, we studied the role of two ATP producing enzymes, which are involved in the synthesis of pyruvate from phosphoenolpyruvate: the glycosomal pyruvate phosphate dikinase (PPDK) and the cytosolic pyruvate kinase (PYK). The parasite was not affected by PPDK gene knockout. In contrast, inhibition of PYK expression by RNA interference was lethal for these cells. In the absence of PYK activity, the intracellular ATP concentration was reduced by up to 2.3-fold, whereas the intracellular pyruvate concentration was not reduced. Furthermore, we show that this mutant cell line still excreted acetate from d-glucose metabolism, and both the wild type and mutant cell lines consumed pyruvate present in the growth medium with similar high rates, indicating that in the absence of PYK activity pyruvate is still present in the trypanosomes. We conclude that PYK is essential because of its ATP production, which implies that the cytosolic substrate level phosphorylation is essential for the growth of procyclic trypanosomes. |
| Databáze: | OpenAIRE |
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