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Procyclic trypanosomes recycle glucose catabolites and TCA cycle intermediates to stimulate growth in the presence of physiological amounts of proline

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Villafraz, Oriana [1] ; Biran, Marc [2] ; Pineda, Erika [1] ; Plazolles, Nicolas [1] ; Cahoreau, Edern [3, 4] ; Ornitz Oliveira Souza, Rodolpho [5] ; Thonnus, Magali [1] ; Allmann, Stefan [6] ; Tetaud, Emmanuel [1] ; Riviere, Loic [1] ; Silber, Ariel M. [5] ; Barrett, Michael P. [7, 8] ; Zikova, Alena [9] ; Boshart, Michael [6] ; Portais, Jean-Charles [3, 4, 10] ; Bringaud, Frederic [1]
Número total de Autores: 16
Afiliação do(s) autor(es):
[1] Univ Bordeaux, CNRS, Microbiol Fondamentale & Pathogenicite MFP, UMR 5234, Bordeaux - France
[2] Univ Bordeaux, CNRS, Ctr Resonance Magnet Syst Biol CRMSB, UMR 5536, Bordeaux - France
[3] TBI INSA Toulouse INSA, CNRS UMR INSA 5504, INRA 792, Toulouse Biotechnol Inst, Toulouse - France
[4] MetaToul MetaboHub, Natl Infrastruct Metabol & Flux, Toulouse - France
[5] Univ Sao Paulo, Inst Biomed Sci, Dept Parasitol, Lab Biochem Tryps LaBTryps, Sao Paulo - Brazil
[6] Ludwig Maximilians Univ Munchen, Fak Biol Genet, Grosshadernerstr 2-4, Martinsried - Germany
[7] Univ Glasgow, Coll Med Vet & Life Sci, Inst Infect Immun & Inflammat, Wellcome Ctr Integrat Parasitol, Glasgow, Lanark - Scotland
[8] Univ Glasgow, Coll Med Vet & Life Sci, Wolfson Wohl Canc Res Ctr, Glasgow Poly, Garscube Campus, Glasgow, Lanark - Scotland
[9] Czech Acad Sci, Biol Ctr, Inst Parasitol, Ceske Budejovice - Czech Republic
[10] Univ Toulouse, RESTORE, Inserm U1031, CNRS 5070, UPS, EFS, ENVT, Toulouse - France
Número total de Afiliações: 10
Tipo de documento: Artigo Científico
Fonte: PLOS PATHOGENS; v. 17, n. 3 MAR 2021.
Citações Web of Science: 1

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 alpha-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 alpha-ketoglutarate consumption (15-times higher than glucose) is possible thanks to the balanced production and consumption of NADH at the substrate level and (iii) alpha-ketoglutarate is toxic for trypanosomes if not appropriately metabolized as observed for an alpha-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 alpha-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. Author summary In the midgut of its insect vector, trypanosomes rely on proline to feed their energy metabolism. However, the availability of other potential carbon sources that can be used by the parasite is currently unknown. Here we show that tricarboxylic acid (TCA) cycle intermediates, i.e. succinate, malate and alpha-ketoglutarate, stimulate growth of procyclic trypanosomes incubated in a medium containing 2 mM proline, which is in the range of the amounts measured in the midgut of the fly. Some of these additional carbon sources are needed for the development of epimastigotes, which differentiate from procyclics in the midgut of the fly, since their growth defect observed in the presence of 2 mM proline is rescued by addition of alpha-ketoglutarate. In addition, we have implemented new approaches to study a poorly explored branch of the TCA cycle converting malate to alpha-ketoglutarate, which was previously described as non-functional in the parasite, regardless of the glucose levels available. The discovery of this branch reveals that a full TCA cycle can operate in procyclic trypanosomes. Our data broaden the metabolic potential of trypanosomes and pave the way for a better understanding of the parasite's metabolism in various organ systems of the tsetse fly, where it develops. (AU)

Processo FAPESP: 16/06034-2 - O papel biológico de aminoácidos e seus metabólitos derivados em Trypanosoma cruzi
Beneficiário:Ariel Mariano Silber
Linha de fomento: Auxílio à Pesquisa - Temático
Processo FAPESP: 18/14432-3 - Uma rede para uma biologia integrativa em doenças negligenciadas: conectando a epigenética, o metabolismo e a biologia celular em tripanossomatídeos patogênicos
Beneficiário:Ariel Mariano Silber
Linha de fomento: Auxílio à Pesquisa - Temático