Mitochondrion of the Trypanosoma brucei long slender bloodstream form is capable of ATP production by substrate-level phosphorylation

PLoS Pathog. 2023 Oct 11;19(10):e1011699. doi: 10.1371/journal.ppat.1011699. eCollection 2023 Oct.


The long slender bloodstream form Trypanosoma brucei maintains its essential mitochondrial membrane potential (ΔΨm) through the proton-pumping activity of the FoF1-ATP synthase operating in the reverse mode. The ATP that drives this hydrolytic reaction has long been thought to be generated by glycolysis and imported from the cytosol via an ATP/ADP carrier (AAC). Indeed, we demonstrate that AAC is the only carrier that can import ATP into the mitochondrial matrix to power the hydrolytic activity of the FoF1-ATP synthase. However, contrary to expectations, the deletion of AAC has no effect on parasite growth, virulence or levels of ΔΨm. This suggests that ATP is produced by substrate-level phosphorylation pathways in the mitochondrion. Therefore, we knocked out the succinyl-CoA synthetase (SCS) gene, a key mitochondrial enzyme that produces ATP through substrate-level phosphorylation in this parasite. Its absence resulted in changes to the metabolic landscape of the parasite, lowered virulence, and reduced mitochondrial ATP content. Strikingly, these SCS mutant parasites become more dependent on AAC as demonstrated by a 25-fold increase in their sensitivity to the AAC inhibitor, carboxyatractyloside. Since the parasites were able to adapt to the loss of SCS in culture, we also analyzed the more immediate phenotypes that manifest when SCS expression is rapidly suppressed by RNAi. Importantly, when performed under nutrient-limited conditions mimicking various host environments, SCS depletion strongly affected parasite growth and levels of ΔΨm. In totality, the data establish that the long slender bloodstream form mitochondrion is capable of generating ATP via substrate-level phosphorylation pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Mitochondria / metabolism
  • Phosphorylation
  • Trypanosoma brucei brucei* / metabolism


  • Adenosine Triphosphate

Grants and funding

This work was supported by Czech Science Foundation grant 20-14409S and by the European Research Council (ERC) (MitoSignal, grant agreement no. 101044951) to AZ. FB and EP were supported by the Centre National de la Recherche Scientifique (CNRS), the Université de Bordeaux, the Agence Nationale de la Recherche (ANR) through grants ADIPOTRYP (ANR19-CE15-0004-01) of the ANR "Générique" call, the Laboratoire d’Excellence (LabEx) ParaFrap ANR-11-LABX-0024 and the "Fondation pour le Recherche Médicale" (FRM) ("Equipe FRM", grant n°EQU201903007845). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.