Functional characterization of methionine sulfoxide reductase B from Trypanosoma cruzi

ARIAS, DIEGO G.; CABEZA, MATÍAS S.; ECHARREN, MA. LAURA; IGLESIAS, ALBERTO A.; GUERRERO, SERGIO A.

Montevideo

Simposio; Simposio sobre Biología Molecular de la Enfermedad de Chagas.; 2012

Instituto Pasteur de Montevideo

Methionine is an amino acid susceptible to being oxidized to methionine sulfoxide (MetSO). The reduction of MetSO to methionine is catalyzed by methionine sulfoxide reductase (MSR), an enzyme present in almost all organisms. In trypanosomatids, the study of antioxidant systems has been mainly focused on the involvement of trypanothione, a specific redox component in these organisms. However, poorly information is available concerning their mechanisms for repairing oxidized proteins, which would be relevant for the survival of these pathogens in the various stages of their life cycle. Recently, we characterized two A-type MSR proteins from T. cruzi and T. brucei. In this work, we report the molecular cloning of a gene encoding a putative B‑type MSR in this pathogen. The gene was expressed in Escherichia coli, and the corresponding recombinant protein was purified and functionally characterized. The enzyme was specific for L-Met(R)SO reduction, using T. cruzi TXNI, TXNII and TRX as the reducing substrates. In addition, we found that TcMSRB could compensate for MSR deficiency in yeast mutant strain lacking both MSRA and MSRB genes. The protein presented redox-dependent change in monomer/dimer oligomerization states. The results support the occurrence of a metabolic pathway in T. cruzi involved in the critical function of repairing oxidized macromolecules.