Mitochondrial F-type adenosine triphosphate (ATP) synthases are commonly introduced as highly conserved membrane-embedded rotary machines generating the majority of cellular ATP. This simplified view neglects recently revealed striking compositional diversity of the enzyme and the fact that in specific life stages of some parasites, the physiological role of the enzyme is to maintain the mitochondrial membrane potential at the expense of ATP rather than to produce ATP. In addition, mitochondrial ATP synthases contribute indirectly to the organelle's other functions because they belong to major determinants of submitochondrial morphology. Here, we review current knowledge about the trypanosomal ATP synthase composition and architecture in the context of recent advances in the structural characterization of counterpart enzymes from several eukaryotic supergroups. We also discuss the physiological function of mitochondrial ATP synthases in three trypanosomatid parasites, Trypanosoma cruzi, Trypanosoma brucei and Leishmania, with a focus on their disease-causing life cycle stages. We highlight the reversed proton-pumping role of the ATP synthase in the T. brucei bloodstream form, the enzyme's potential link to the regulation of parasite's glycolysis and its role in generating mitochondrial membrane potential in the absence of mitochondrial DNA.

• Keywords
• ATP synthase, cryo-EM, mitochondria, mitochondrial membrane potential, oxidative phosphorylation,
• MeSH
• Genetic Engineering * MeSH
• Leishmania enzymology   MeSH
• Membrane Potential, Mitochondrial MeSH
• Mitochondrial Proton-Translocating ATPases genetics   metabolism   MeSH
• Protozoan Proteins genetics   metabolism   MeSH
• Trypanosoma brucei brucei enzymology   MeSH
• Trypanosoma cruzi enzymology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Mitochondrial Proton-Translocating ATPases MeSH
• Protozoan Proteins MeSH

Trypanosoma brucei, a protist responsible for human African trypanosomiasis (sleeping sickness), is transmitted by the tsetse fly where the procyclic forms of the parasite develop in the proline-rich (1-2 mM) and glucose-depleted digestive tract. Proline is essential for the midgut colonization of the parasite in the insect vector, however other carbon sources could be available and used to feed its central metabolism. Here we show that procyclic trypanosomes can consume and metabolize metabolic intermediates, including those excreted from glucose catabolism (succinate, alanine and pyruvate), with the exception of acetate, which is the ultimate end-product excreted by the parasite. Among the tested metabolites, tricarboxylic acid (TCA) cycle intermediates (succinate, malate and α-ketoglutarate) stimulated growth of the parasite in the presence of 2 mM proline. The pathways used for their metabolism were mapped by proton-NMR metabolic profiling and phenotypic analyses of thirteen RNAi and/or null mutants affecting central carbon metabolism. We showed that (i) malate is converted to succinate by both the reducing and oxidative branches of the TCA cycle, which demonstrates that procyclic trypanosomes can use the full TCA cycle, (ii) the enormous rate of α-ketoglutarate consumption (15-times higher than glucose) is possible thanks to the balanced production and consumption of NADH at the substrate level and (iii) α-ketoglutarate is toxic for trypanosomes if not appropriately metabolized as observed for an α-ketoglutarate dehydrogenase null mutant. In addition, epimastigotes produced from procyclics upon overexpression of RBP6 showed a growth defect in the presence of 2 mM proline, which is rescued by α-ketoglutarate, suggesting that physiological amounts of proline are not sufficient per se for the development of trypanosomes in the fly. In conclusion, these data show that trypanosomes can metabolize multiple metabolites, in addition to proline, which allows them to confront challenging environments in the fly.

• MeSH
• Citric Acid Cycle drug effects   MeSH
• Glucose metabolism   MeSH
• Insect Vectors parasitology   MeSH
• Tsetse Flies drug effects   parasitology   MeSH
• Oxidation-Reduction drug effects   MeSH
• Proline metabolism   pharmacology   MeSH
• RNA Interference physiology   MeSH
• Trypanosoma brucei brucei drug effects   metabolism   MeSH
• Trypanosoma drug effects   metabolism   MeSH
• Trypanosomiasis, African drug therapy   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Glucose MeSH
• Proline MeSH

Trypanosoma brucei is a parasitic protozoan that undergoes a complex life cycle involving insect and mammalian hosts that present dramatically different nutritional environments. Mitochondrial metabolism and gene expression are highly regulated to accommodate these environmental changes, including regulation of mRNAs that require extensive uridine insertion/deletion (U-indel) editing for their maturation. Here, we use high throughput sequencing and a method for promoting life cycle changes in vitro to assess the mechanisms and timing of developmentally regulated edited mRNA expression. We show that edited CYb mRNA is downregulated in mammalian bloodstream forms (BSF) at the level of editing initiation and/or edited mRNA stability. In contrast, edited COIII mRNAs are depleted in BSF by inhibition of editing progression. We identify cell line-specific differences in the mechanisms abrogating COIII mRNA editing, including the possible utilization of terminator gRNAs that preclude the 3' to 5' progression of editing. By examining the developmental timing of altered mitochondrial mRNA levels, we also reveal transcript-specific developmental checkpoints in epimastigote (EMF), metacyclic (MCF), and BSF. These studies represent the first analysis of the mechanisms governing edited mRNA levels during T. brucei development and the first to interrogate U-indel editing in EMF and MCF life cycle stages.

• MeSH
• RNA Editing genetics   MeSH
• RNA, Guide, Kinetoplastida genetics   MeSH
• RNA, Messenger genetics   MeSH
• Mitochondria genetics   MeSH
• Protozoan Proteins genetics   MeSH
• RNA, Mitochondrial genetics   MeSH
• RNA, Protozoan genetics   MeSH
• RNA Stability genetics   MeSH
• Trypanosoma brucei brucei genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• RNA, Guide, Kinetoplastida MeSH
• RNA, Messenger MeSH
• mitochondrial messenger RNA MeSH Browser
• Protozoan Proteins MeSH
• RNA, Mitochondrial MeSH
• RNA, Protozoan MeSH