Trypanosoma cruzi synthesizes proline via a Δ1-pyrroline-5-carboxylate reductase whose activity is fine-tuned by NADPH cytosolic pools.

Trypanosoma cruzi synthesizes proline via a Δ1-pyrroline-5-carboxylate reductase whose activity is fine-tuned by NADPH cytosolic pools. Biochem J. 2020 Apr 21;: Authors: Marchese LM, Olavarria KM, Mantilla BS, Avila CC, Souza ROO, Damasceno FS, Elias MC, Silber AM Abstract In Trypanosoma 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. Δ1-Pyrroline-5-carboxylate reductase (P5CR, EC 1.5.1.2) catalyzes the biosynthesis of proline from Δ1-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 a NADPH-dependent cytosolic enzyme with a Km app for P5C of 23.9 mM and with a higher expression in the insect-resident form of 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 (Ki app = 45 ± 0.7 µM). Therefore, TcP5CR is a candidate as a regulatory factor o...
Source: The Biochemical Journal - Category: Biochemistry Authors: Tags: Biochem J Source Type: research