title: Contribution of pyruvate phosphate dikinase in the maintenance of the glycosomal ATP/ADP balance in the Trypanosoma brucei procyclic form.
abstract: Trypanosoma brucei belongs to a group of protists that sequester the first six or seven glycolytic steps inside specialized peroxisomes, named glycosomes. Because of the glycosomal membrane impermeability to nucleotides, ATP molecules consumed by the first glycolytic steps need to be regenerated in the glycosomes by kinases, such as phosphoenolpyruvate carboxykinase (PEPCK). The glycosomal pyruvate phosphate dikinase (PPDK), which reversibly converts phosphoenolpyruvate into pyruvate, could also be involved in this process. To address this question, we analyzed the metabolism of the main carbon sources used by the procyclic trypanosomes (glucose, proline, and threonine) after deletion of the PPDK gene in the wild-type (Δppdk) and PEPCK null (Δppdk/Δpepck) backgrounds. The rate of acetate production from glucose is 30% reduced in the Δppdk mutant, whereas threonine-derived acetate production is not affected, showing that PPDK function in the glycolytic direction with production of ATP in the glycosomes. The Δppdk/Δpepck mutant incubated in glucose as the only carbon source showed a 3.8-fold reduction of the glycolytic rate compared with the Δpepck mutant, as a consequence of the imbalanced glycosomal ATP/ADP ratio. The role of PPDK in maintenance of the ATP/ADP balance was confirmed by expressing the glycosomal phosphoglycerate kinase (PGKC) in the Δppdk/Δpepck cell line, which restored the glycolytic flux. We also observed that expression of PGKC is lethal for procyclic trypanosomes, as a consequence of ATP depletion, due to glycosomal relocation of cytosolic ATP production. This illustrates the key roles played by glycosomal and cytosolic kinases, including PPDK, to maintain the cellular ATP/ADP homeostasis.
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Kamel
authors.initials: K
authors.lastname: Deramchia
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Pauline
authors.initials: P
authors.lastname: Morand
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Biran
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Millerioux
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Mazet
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Wargnies
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Franconi
authors.affiliation: From the Centre de Résonance Magnétique des Systèmes Biologiques, Université de Bordeaux, CNRS UMR-5536, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France bringaud@rmsb.u-bordeaux2.fr.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bringaud
mesh_terms: D000244:Adenosine Diphosphate / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology*; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011772:Pyruvate, Orthophosphate Dikinase / Q000235:genetics / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics
chemical_list: D015800:Protozoan Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011772:Pyruvate, Orthophosphate Dikinase; D019764:Phosphoenolpyruvate Carboxykinase (ATP)
keywords: Gene Knockout; Glucose Metabolism; Parasite Metabolism; Peroxisome; Trypanosoma brucei