Trypanosoma cruzi: characterisation of the gene encoding tyrosine aminotransferase in benznidazole-resistant and susceptible populations

Exp Parasitol. 2008 Jan;118(1):111-7. doi: 10.1016/j.exppara.2007.05.013. Epub 2007 Jun 12.

Abstract

Various biochemical differences exist between mammalian tyrosine aminotransferase (TAT) and its analogue in Trypanosoma cruzi (TcTAT), the causative agent of Chagas disease. Moreover, TcTAT is over-expressed in strains of the parasite that are resistant to benznidazole (BZ), a drug currently used in chemotherapy. TAT has thus been indicated as a potential target for the development of new chemotherapeutic agents. In the present study, the TcTAT gene has been characterised in 14 BZ-resistant and susceptible strains and clones of T. cruzi. A unique transcript of 2.0kb and similar levels of TcTAT mRNA were observed in all parasite populations. TcTAT gene is organized in a tandem multicopy array and is located on 8 chromosomal bands that vary from 785-2500kb. No amplification of TcTAT was observed in the parasite genome. A 42kDa protein expressed by TcTAT was present in all T. cruzi samples. The results suggest that TcTAT is not directly associated with the T. cruzi drug resistance phenotype. However, it may act as a general secondary compensatory mechanism or stress response factor rather than as a key component of the specific primary resistance mechanism in T. cruzi.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Northern
  • Blotting, Southern
  • Blotting, Western
  • Cloning, Molecular
  • DNA, Protozoan / analysis
  • Drug Resistance / genetics*
  • Electrophoresis, Gel, Pulsed-Field
  • Gene Expression Regulation, Enzymologic / genetics
  • Nitroimidazoles / pharmacology*
  • RNA, Messenger / metabolism
  • RNA, Protozoan / analysis
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription, Genetic
  • Trypanocidal Agents / pharmacology*
  • Trypanosoma cruzi / drug effects
  • Trypanosoma cruzi / enzymology*
  • Trypanosoma cruzi / genetics*
  • Tyrosine Transaminase / genetics*
  • Tyrosine Transaminase / immunology

Substances

  • DNA, Protozoan
  • Nitroimidazoles
  • RNA, Messenger
  • RNA, Protozoan
  • Recombinant Proteins
  • Trypanocidal Agents
  • Tyrosine Transaminase
  • benzonidazole