Transsulfuration is an active pathway for cysteine biosynthesis in Trypanosoma rangeli

• Published in: Parasites & vectors Vol. 7; no. 1; p. 197
• Main Authors: Romero, Ibeth, Téllez, Jair, Eiko Yamanaka, Lais, Steindel, Mario, José Romanha, Alvaro, Carlos Grisard, Edmundo
• Format: Journal Article
• Language: English
• Published: England Springer-Verlag 24.04.2014; BioMed Central Ltd; BioMed Central; BMC
• Subjects: active sites; Amino Acid Sequence; Animals; Antioxidant defence; antioxidants; Bacteria; Biosynthesis; Cloning; Cloning, Molecular; cystathionine; cystathionine beta-synthase; Cystathionine beta-Synthase - genetics; Cystathionine beta-Synthase - metabolism; Cystathionine β-synthase; cysteine; Cysteine - biosynthesis; Cysteine synthase; Cysteine Synthase - genetics; Cysteine Synthase - metabolism; Deoxyribonucleic acid; developmental stages; DNA; enzyme activity; Enzymes; Free radicals; Gene Expression Regulation, Enzymologic; genes; Genomes; glutathione; homeostasis; Hydrogen peroxide; insects; lysine; Mammals; methylation; Molecular Sequence Data; Oxidative Stress; Parasites; Phosphatidylethanolamines; protein synthesis; Proteins; Protozoa; serine; Species Specificity; spermidine; T. rangeli; Thiol metabolism; thiols; Trypanosoma cruzi; Trypanosoma cruzi - enzymology; Trypanosoma rangeli; Trypanosoma rangeli - enzymology
• ISSN: 1756-3305; 1756-3305
• DOI: 10.1186/1756-3305-7-197

BACKGROUND: Cysteine, a sulfur-containing amino acid, plays an important role in a variety of cellular functions such as protein biosynthesis, methylation, and polyamine and glutathione syntheses. In trypanosomatids, glutathione is conjugated with spermidine to form the specific antioxidant thiol trypanothione (T[SH]₂) that plays a central role in maintaining intracellular redox homeostasis and providing defence against oxidative stress. METHODS: We cloned and characterised genes coding for a cystathionine β-synthase (CβS) and cysteine synthase (CS), key enzymes of the transsulfuration and assimilatory pathways, respectively, from the hemoflagellate protozoan parasite Trypanosoma rangeli. RESULTS: Our results show that T. rangeli CβS (TrCβS), similar to its homologs in T. cruzi, contains the catalytic domain essential for enzymatic activity. Unlike the enzymes in bacteria, plants, and other parasites, T. rangeli CS lacks two of the four lysine residues (Lys²⁶and Lys¹⁸⁴) required for activity. Enzymatic studies using T. rangeli extracts confirmed the absence of CS activity but confirmed the expression of an active CβS. Moreover, CβS biochemical assays revealed that the T. rangeli CβS enzyme also has serine sulfhydrylase activity. CONCLUSION: These findings demonstrate that the RTS pathway is active in T. rangeli, suggesting that this may be the only pathway for cysteine biosynthesis in this parasite. In this sense, the RTS pathway appears to have an important functional role during the insect stage of the life cycle of this protozoan parasite.