Transsulfuration is an active pathway for cysteine biosynthesis in Trypanosoma rangeli

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 (Lys26 and 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

Synthesis of xylitan derivatives and preliminary evaluation of in vitro trypanocidal activity

A series of novel xylitan derivatives derived from xylitol were synthesized using operationally simple procedures. A xylitan acetonide was the key intermediate used to prepare benzoate, arylsulfonate esters and 1,2,3-triazole derivatives of xylitan. These compounds were evaluated for their in vitro anti-Trypanosoma cruzi activity against trypomastigote and amastigote forms of the parasite in T. cruzi-infected cell lineages. Benznidazole was used as positive control against T. cruzi and cytotoxicity was determined in mammalian L929 cells. The arylsulfonate xylitan derivative bearing a nitro group displayed the best activity of all the compounds tested, and was slightly more potent than the reference drug benznidazole. The importance of the isopropylidene ketal moiety was established and the greater lipophilicity of these compounds suggests enhancement in cell penetration2110CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIG473461/2013-7CEX-RED-00010-1

The anticancer drug tamoxifen is active against Trypanosoma cruzi in vitro but ineffective in the treatment of the acute phase of Chagas disease in mice

The activity of the antineoplastic drug tamoxifen was evaluated against Trypanosoma cruzi. In vitro activity was determined against epimastigote, trypomastigote and amastigote forms of CL14, Y and Y benznidazole resistant T. cruzi strains. Regardless of the strain used, the drug was active against all life-cycle stages of the parasite with a half maximal effective concentration ranging from 0.7-17.9 µM. Two experimental models of acute Chagas disease were used to evaluate the in vivo efficacy of treatment with tamoxifen. No differences in parasitemia and mortality were observed between control mock-treated and tamoxifen-treated mice.FAPESPFIOCRUZCNP

Molecular characterization of Cyclophilin (TcCyP19) in Trypanosoma cruzi populations susceptible and resistant to benznidazole

Cyclophilin (TcCyP19), a peptidyl-prolyl cis/trans isomerase, is a key molecule with diverse biological functions that include roles in molecular chaperoning, stress response, immune modulation, and signal transduction. In this respect, TcCyP19 could serve as a potential drug target in diseasecausing parasites. Previous studies employing proteomics techniques have shown that the TcCyP19 isoform was more abundant in a benznidazole (BZ)-resistant Trypanosoma cruzi population than in its susceptible counterpart. In this study, TcCyP19 has been characterized in BZ-susceptible and BZresistant T. cruzi populations. Phylogenetic analysis revealed a clear dichotomy between Cyphophilin A (CyPA) sequences from trypanosomatids and mammals. Sequencing analysis revealed that the amino acid sequences of TcCyP19 were identical among the T. cruzi samples analyzed. Southern blot analysis showed that TcCyP19 is a single-copy gene, located in chromosomal bands varying in size from 0.68 to 2.2 Mb, depending on the strain of T. cruzi. Northern blot and qPCR indicated that the levels of TcCyP19 mRNA were two-fold higher in drug-resistant T. cruzi populations than in their drugsusceptible counterparts. Similarly, as determined by two-dimensional gel electrophoresis immunoblot, the expression of TcCyP19 protein was increased to the same degree in BZ-resistant T. cruzi populations. No differences in TcCyP19 mRNA and protein expression levels were observed between the susceptible and the naturally resistant T. cruzi strains analyzed. Taken together, these data indicate that cyclophilin TcCyP19 expression is up-regulated at both transcriptional and translational levels in T. cruzi populations that were in vitro-induced and in vivo-selected for resistance to BZ.Fil: Rêgo, Juciane Vaz. Universidade Federal Do Piaui.; BrasilFil: Duarte, Ana Paula. Fundación Oswaldo Cruz; BrasilFil: Liarte, Daniel Barbosa. Universidade Federal Do Piaui.; BrasilFil: de Carvalho Sousa, Francirlene. Universidade Federal Do Piaui.; BrasilFil: Barreto, Humberto Medeiros. Universidade Federal Do Piaui.; BrasilFil: Bua, Jacqueline Elena. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”. Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben”; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Romanha, Alvaro José. Fundación Oswaldo Cruz; BrasilFil: Rádis Baptista, Gandhi. Universidade Federal Do Piaui.; BrasilFil: Murta, Silvane Maria Fonseca. Universidade Federal Do Piaui.; Brasi

Recommendations from a Satellite Meeting (International Symposium to Commemorate the 90th Anniversary of the Discovery of Chagas Disease, April 11-16 1999, Rio de Janeiro, Brazil)

During this symposium the standardization of the nomenclature of Trypanosoma cruzi strains was discussed, in a parallel session, with a view to facilitating the use and understanding of a common nomenclature that would serve not only taxonomists but the general community of researchers working with T. cruzi. The diversity in the behavior and morphology of T. cruzi isolates was soon recognized after the discovery of Chagas disease. Since then a variety of biochemical and molecular techniques have revealed the great genetic diversity present in strains of this parasite. Different investigators have described this diversity by using various terms. Correlation between this diversity and the complex epidemiological and clinical manifestations of the disease has however been hindered by the lack of a common nomenclature. Recent studies have indicated a convergence among investigators regarding the clustering of strains of T. cruzi, into two principal groups. This consensus, together with the report of a meeting on the standardization of methods for T. cruzi classification held in Panama (unpublished document TDR/EPICHA-TCC/85.3 Geneva, World Health Organization, 1985), form the basis of the recommendations outlined in this document