Abstract
BackgroundThe glyoxalase pathway, which includes two enzymes, glyoxalase 1 and 2 (Glo1 and Glo2), is a ubiquitous cellular system responsible for the removal of cytotoxic methylglyoxal produced during glycolysis. Protozoan parasites, including Toxoplasma gondii (T. gondii) tachyzoites, produce methylglyoxal because of increased glycolytic fluxes. A Glo1 inhibitor such as curcumin could be considered a drug candidate for anti-protozoan, anti-inflammatory, and anti-cancer therapy.MethodsThe T. gondii Glo1 gene (TgGlo1) was cloned and the recombinant protein was produced. Enzyme kinetics of TgGlo1 and five mutants were evaluated by adding methylglyoxal and glutathione to a reaction mixture. Finally, the inhibitory effects of various concentrations of curcumin on recombinant TgGlo1 were evaluated using in vitro cultures of T. gondii.ResultsActive recombinant TgGlo1 was successfully produced and the active sites (E166 and E251) of TgGlo1 were verified by point mutagenesis. Curcumin at the tested doses inhibited the enzymatic activity of recombinant TgGlo1 as well as the parasitic propagation of in vitro-cultured T. gondii. The Ki and IC50 were 12.9 ± 0.5 μM and 38.3 ± 0.9 μM, respectively.ConclusionThe inhibitory effect of curcumin on the enzymatic activity of TgGlo1 and parasitic propagation of T. gondii could be explored in the potential development of a potent drug for the treatment of toxoplasmosis. However, considering the fact that curcumin is known to have many effects on other molecules in the micromolar range, further elucidation of curcumin’s direct inhibition of the glyoxalase system of T. gondii will be needed.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1268-5) contains supplementary material, which is available to authorized users.
Highlights
The glyoxalase pathway, which includes two enzymes, glyoxalase 1 and 2 (Glo1 and Glo2), is a ubiquitous cellular system responsible for the removal of cytotoxic methylglyoxal produced during glycolysis
Characterization of T. gondii glyoxalase 1 T. gondii Glo1 gene (TgGlo1) was amplified from cDNA of a T. gondii RH strain and contained a single open reading frame of 1008 nucleotides encoding a polypeptide of 336 amino acid residues
The purity of rTgGlo1 was confirmed by SDS-PAGE (Additional file 1: Figure S1)
Summary
The glyoxalase pathway, which includes two enzymes, glyoxalase 1 and 2 (Glo and Glo2), is a ubiquitous cellular system responsible for the removal of cytotoxic methylglyoxal produced during glycolysis. Protozoan parasites, including Toxoplasma gondii (T. gondii) tachyzoites, produce methylglyoxal because of increased glycolytic fluxes. The parasites differentiate into tachyzoites and bradyzoites, The glyoxalase pathway is the ubiquitous cellular system responsible for the removal of methylglyoxal, a cytotoxic reactive carbonyl compound produced in many organisms as a consequence of central metabolism [4,5,6]. Plasmodium species, which are apicomplexan parasites closely related to T. gondii, show increased methylglyoxal production [8, 9]. The increased glycolytic fluxes in T. gondii tachyzoites would suggest that these parasites require an efficient detoxification system for removal of harmful methylglyoxal. While there are several reports of studies focusing on the glyoxalase system of Plasmodium species as a potential drug target, no such study has been reported in T. gondii to date [10]
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