ATP synthesis-coupled and -uncoupled acetate production from acetyl-CoA by mitochondrial acetate:succinate CoA-transferase and acetyl-CoA thioesterase in Trypanosoma |
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Authors: | Millerioux Yoann Morand Pauline Biran Marc Mazet Muriel Moreau Patrick Wargnies Marion Ebikeme Charles Deramchia Kamel Gales Lara Portais Jean-Charles Boshart Michael Franconi Jean-Michel Bringaud Frédéric |
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Institution: | Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, Université Bordeaux Segalen, CNRS, 146 Rue Léo Saignat, 33076 Bordeaux, France. |
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Abstract: | Insect stage trypanosomes use an "acetate shuttle" to transfer mitochondrial acetyl-CoA to the cytosol for the essential fatty acid biosynthesis. The mitochondrial acetate sources are acetate:succinate CoA-transferase (ASCT) and an unknown enzymatic activity. We have identified a gene encoding acetyl-CoA thioesterase (ACH) activity, which is shown to be the second acetate source. First, RNAi-mediated repression of ASCT in the ACH null background abolishes acetate production from glucose, as opposed to both single ASCT and ACH mutants. Second, incorporation of radiolabeled glucose into fatty acids is also abolished in this ACH/ASCT double mutant. ASCT is involved in ATP production, whereas ACH is not, because the ASCT null mutant is ~1000 times more sensitive to oligomycin, a specific inhibitor of the mitochondrial F(0)/F(1)-ATP synthase, than wild-type cells or the ACH null mutant. This was confirmed by RNAi repression of the F(0)/F(1)-ATP synthase F(1)β subunit, which is lethal when performed in the ASCT null background but not in the wild-type cells or the ACH null background. We concluded that acetate is produced from both ASCT and ACH; however, only ASCT is responsible, together with the F(0)/F(1)-ATP synthase, for ATP production in the mitochondrion. |
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Keywords: | Energy Metabolism Metabolomics F1F0-ATPase Glucose Metabolism Mitochondrial Metabolism Procyclic Trypanosoma brucei Acetate Production Acetate:Succinate CoA-transferase Acetyl-CoA Thioesterase RNA Interference and Knockout Mitochondrial ATP Production |
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