3-Mercaptopyruvate Sulfurtransferase of LeishmaniaContains an Unusual C-terminal Extension and Is Involved in Thioredoxin and Antioxidant Metabolism

Abstract

Cytosolic 3-mercaptopyruvate sulfurtransferases (EC 2.8.1.2) of Leishmania major and Leishmania mexicana have been cloned, expressed as active enzymes in Escherichia coli, and characterized. The leishmanial singlecopy genes predict a sulfurtransferase that is structurally peculiar in possessing a C-terminal domain of some 70 amino acids. Homologous genes of Trypanosoma cruzi and Trypanosoma brucei encode enzymes with a similar C-terminal domain, suggesting that this feature, not known in any other sulfurtransferase, is a characteristic of trypanosomatid parasites. Short truncations of the C-terminal domain resulted in misfolded inactive proteins, demonstrating that the domain plays some key role in facilitating correct folding of the enzymes. The leishmanial recombinant enzymes exhibited high activity toward 3-mercaptopyruvate and catalyzed the transfer of sulfane sulfur to cyanide to form thiocyanate. They also used thiosulfate as a substrate and reduced thioredoxin as the accepting nucleophile, the latter being oxidized. The enzymes were expressed in all life cycle stages, and the expression level was increased under peroxide or hypo-sulfur stress. The results are consistent with the enzymes having an involvement in the synthesis of sulfur amino acids per se or iron-sulfur centers of proteins and the parasite's management of oxidative stress.

Alterations in the diabetic myocardial proteome coupled with increased myocardial oxidative stress underlies diabetic cardiomyopathy

“…However, it has been reported that MST can both oxidize thioredoxin, a key intermediate in cellular redox reactions, and react with peroxides and that this may be a physiologically significant mechanism for combating oxidative challenges [41,42]. Recently, it has been reported that overexpression of ALDH-2 confers lung epithelial cell resistance to hyperoxia-induced cell death in part by reducing intracellular and mitochondrialderived ROS production [43].…”

Leishmania major Expresses a Single Dihydroxyacetone Phosphate Acyltransferase Localized in the Glycosome, Important for Rapid Growth and Survival at High Cell Density and Essential for Virulence

“…This domain does not share homology with any known proteins in the available databases. The presence of an unusual polypeptide extension has also been found in the subunit II of RNA polymerase I of T. brucei and L. major, which harbor an N-terminal 250 amino acid extension (40,41), and the 3-mercaptopyruvate sulfur-transferase enzymes of L. major and Leishmania mexicana, which contain 70 additional amino acids at their C terminus (42). So far no function could be assigned to these domains.…”

Characterization and Interaction Studies of Two Isoforms of the Dual Localized 3-Mercaptopyruvate Sulfurtransferase TUM1 from Humans

“…The TUM1-bound persulfide can be transferred to acceptors such as cyanide to generate the less toxic thiocyanate (44). Alternatively, H 2 S can be released from TUM1 in the presence of reducing systems like thioredoxin or glutathione (45,46). Inhibition of TUM1 conserves cysteine and contributes to an increase in the cysteine pool (47,48).…”