Metabolic flexibilities and vulnerabilities in the pentose phosphate pathway of the zoonotic pathogen Toxoplasma gondii

Abstract

Metabolic pathways underpin the growth and virulence of intracellular parasites and are therefore promising antiparasitic targets. The pentose phosphate pathway (PPP) is vital in most organisms, providing a reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) and ribose sugar for nucleotide synthesis; however, it has not yet been studied in Toxoplasma gondii, a widespread intracellular pathogen and a model protozoan organism. Herein, we show that T. gondii has a functional PPP distributed in the cytoplasm and nucleus of its acutely-infectious tachyzoite stage. We produced eight parasite mutants disrupting seven enzymes of the PPP in T. gondii. Our data show that of the seven PPP proteins, the two glucose-6-phosphate dehydrogenases (TgG6PDH1, TgG6PDH2), one of the two 6-phosphogluconate dehydrogenases (Tg6PGDH1), ribulose-5-phosphate epimerase (TgRuPE) and transaldolase (TgTAL) are dispensable in vitro as well as in vivo, disclosing substantial metabolic plasticity in T. gondii. Among these, TgG6PDH2 plays a vital role in defense against oxidative stress by the pathogen. Further, we show that Tg6PGDH2 and ribulose-5-phosphate isomerase (TgRPI) are critical for tachyzoite growth. The depletion of TgRPI impairs the flux of glucose in central carbon pathways, and causes decreased expression of ribosomal, microneme and rhoptry proteins. In summary, our results demonstrate the physiological need of the PPP in T. gondii while unraveling metabolic flexibility and antiparasitic targets.

PP2Acα-B′/PR61 Holoenzyme of Toxoplasma gondii Is Required for the Amylopectin Metabolism and Proliferation of Tachyzoites

“…3A–C ). This may be associated with carbohydrate metabolism (including, but likely not limited to polysaccharide accumulation), and its interruption has been reported to be harmful to this parasite ( 16 , 20 – 23 ). However, tachyzoites exposed to 2 μM OA significantly decreased their ability to adhere to and invade host cells, which is consistent with the results of previous reports ( 24 ).…”

“…Freshly harvested tachyzoites ( n = 200) were used to infect HFF-1 cells cultured in high glucose DMEM (BI, Israel) containing 20% fetal bovine serum (FBS) (Gibco, South America) in a 6-well plate. After 7 days of culture, the cells on coverslips were fixed with methanol for 30 min and then stained with 0.2% crystal violet in PBS for 30 min, and this was followed by two washes in PBS and air drying ( 23 ). The numbers and areas of plaques were counted/measured using ImageJ (National Institutes of Health, USA) and analyzed using the GraphPad Prism 8 software (GraphPad Software, USA).…”

Disulfidptosis-related Long Non-Coding RNA signature predicts the prognosis, tumor microenvironment, immunotherapy, and antitumor drug options in colon adenocarcinoma

“…SLC7A11 high expression, glucose starvation, and aberrant disul de bonds are the three signature characteristics of disul dptosis. Firstly, glucose deprivation leads to nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) depletion [20]. Then, high uptake of extracellular cysteine and excessive accumulation of intracellular cysteine, exacerbating disul de bond stress in cell metabolism [21,22].…”

Disulfidptosis-related lncRNAs predict prognosis and immune response of Liver hepatocellular carcinoma

“…There are three main stages in the process of causing disu dptosis, (1) high expression of SLC7A11, which imports extracellular cysteine into intracellular glutamate, resulting in high uptake of extracellular cysteine and excessive intracellular accumulation contributing to disul de bonding in cellular metabolism [16] . (2) In the presence of glucose starvation, it can promote the production of reduced NADPH by the pentose phosphate pathway [17] . (3) Finally, disul de bonds are formed between the actin backbone.…”