The level of ascorbate peroxidase is enhanced in benznidazole-resistant populations of Trypanosoma cruzi and its expression is modulated by stress generated by hydrogen peroxide

• Published in: Memórias do Instituto Oswaldo Cruz Vol. 107; no. 4; pp. 494 - 502
• Main Authors: Nogueira, Fernanda Barbosa, Rodrigues, Joyce Fernanda A, Correa, Marcos Messias S, Ruiz, Jerônimo Conceição, Romanha, Alvaro José, Murta, Silvane Maria Fonseca
• Format: Journal Article
• Language: English
• Published: Brazil Fundação Oswaldo Cruz, Fiocruz 01-06-2012; Instituto Oswaldo Cruz, Ministério da Saúde; Fundação Oswaldo Cruz (FIOCRUZ)
• Subjects: ascorbate peroxidase; Ascorbate Peroxidases - analysis; Ascorbate Peroxidases - genetics; Blotting, Western; DNA, Protozoan - analysis; drug resistance; Drug Resistance - genetics; Electrophoresis, Gel, Pulsed-Field; hydrogen peroxide; Hydrogen Peroxide - pharmacology; Molecular Sequence Data; Nitroimidazoles - pharmacology; PARASITOLOGY; Phylogeny; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Sequence Analysis, DNA; TROPICAL MEDICINE; Trypanocidal Agents - pharmacology; Trypanosoma cruzi; Trypanosoma cruzi - drug effects; Trypanosoma cruzi - drug resistance - ascorbate peroxidase - hydrogen peroxide; Trypanosoma cruzi - enzymology; ascorbate peroxidase; drug resistance; hydrogen peroxide; Trypanosoma cruzi
• ISSN: 1678-8060; 0074-0276; 1678-8060; 0074-0276
• DOI: 10.1590/S0074-02762012000400009

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 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 . 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.