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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 107, No. 4, 2012, pp. 494-502
Bioline Code: oc12072
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 107, No. 4, 2012, pp. 494-502

 en The level of ascorbate peroxidase is enhanced in benznidazole-resistant populations of Trypanosoma cruzi check for this species in other resources and its expression is modulated by stress generated by hydrogen peroxide
Nogueira, Fernanda Barbosa; Rodrigues, Joyce Fernanda A; Correa, Marcos Messias S; Ruiz, Jerônimo Conceição; Romanha, Alvaro José & Murta, Silvane Maria Fonseca

Abstract

Ascorbate peroxidases (APX) are class I heme-containing enzymes that convert hydrogen peroxide into water molecules. The gene encoding APX has been characterized in 11 strains of Trypanosoma cruzi check for this species in other resources that are sensitive or resistant to benznidazole (BZ). Bioinformatic analysis revealed the presence of two complete copies of the T. cruzi APX (TcAPX) gene in the genome of the parasite, while karyotype analysis showed that the gene was present in the 2.000-kb chromosome of all of the strains analyzed. The sequence of TcAPX exhibited greater levels of similarity to those of orthologous enzymes from Leishmania spp than to APXs from the higher plant Arabidopsis thaliana check for this species in other resources . Northern blot and real-time reverse transcriptase polymerase chain reaction (RT-PCR) analyses revealed no significant differences in TcAPX mRNA levels between the T. cruzi strains analyzed. On the other hand, Western blots showed that the expression levels of TcAPX protein were, respectively, two and three-fold higher in T. cruzi populations with in vitro induced (17 LER) and in vivo selected (BZR) resistance to BZ, in comparison with their corresponding susceptible counterparts. Moreover, the two BZ-resistant populations exhibited higher tolerances to exogenous hydrogen peroxide than their susceptible counterparts and showed TcAPX levels that increased in a dose-dependent manner following exposure to 100 and 200 μM hydrogen peroxide.

Keywords
Trypanosoma cruzi - drug resistance - ascorbate peroxidase - hydrogen peroxide

 
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