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Trypanosoma cruzi synthesizes proline via a Delta(1)-pyrroline-5-carboxylate reductase whose activity is fine-tuned by NADPH cytosolic pools

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Autor(es):
Marchese, Leticia [1] ; Olavarria, Karel [2] ; Suarez Mantilla, Brian [1, 3] ; Cristi Avila, Carla [4] ; Oliveira Souza, Rodolpho Ornitiz [1] ; Silva Damasceno, Flavia [1] ; Carolina Elias, Maria [4] ; Mariano Silber, Ariel [1]
Número total de Autores: 8
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Biomed Sci, Dept Parasitol, Lab Biochem Tryps LaBTryps, BR-05508000 Sao Paulo - Brazil
[2] Univ Sao Paulo, Inst Biomed Sci, Dept Microbiol, BR-05508000 Sao Paulo - Brazil
[3] Univ Durham, Dept Biosci, Durham DH7 6SL - England
[4] Butantan Inst, Ctr Toxins Immune Response & Cell Signaling, BR-05503900 Sao Paulo, SP - Brazil
Número total de Afiliações: 4
Tipo de documento: Artigo Científico
Fonte: Biochemical Journal; v. 477, n. 10, p. 1827-1845, MAY 2020.
Citações Web of Science: 0
Resumo

In Try parrosoma cruzi, the etiological agent of Chagas disease, the amino acid proline participates in processes related to T. cruzi survival and infection, such as ATP production, cell differentiation, host-cell invasion, and in protection against osmotic, nutritional, and thermal stresses and oxidative imbalance. However, little is known about proline biosynthesis in this parasite. Delta(1)-Pyrroline-5-carboxylate reductase (P5CR, EC 1.5.1.2) catalyzes the biosynthesis of praline from Delta(1)-pyrroline-5-carboxylate (P5C) with concomitant NADPH oxidation. Herein, we show that unlike other eukaryotes, T. cruzi biosynthesizes proline from P5C, which is produced exclusively from glutamate. We found that TcP5CR is an NADPH-dependent cytosolic enzyme with a K-m(app) for P5C of 27.7 mu M and with a higher expression in the insect-resident form of the parasite. High concentrations of the co-substrate NADPH partially inhibited TcP5CR activity, prompting us to analyze multiple kinetic inhibition models. The model that best explained the obtained data included a non-competitive substrate inhibition mechanism (K-i(app) 45 +/- 0.7 mu M). Therefore, TcP5CR is a candidate as a regulatory factor of this pathway. Finally, we show that P5C can exit trypanosomatid mitochondria in conditions that do not compromise organelle integrity. These observations, together with previously reported results, lead us to propose that in T. cruzi TcP5CR participates in a redox shuttle between the mitochondria and the cytoplasm. In this model, cytoplasmic redox equivalents from NADPH pools are transferred to the mitochondria using praline as a reduced metabolite, and shuttling to fuel electrons to the respiratory chain through proline oxidation by its cognate dehydrogenase. (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