Cloning and characterization of peroxiredoxin in Babesia bovis.

We have identified the 2-Cys peroxiredoxin (Prx) from a bovine Babesia parasite, B. bovis. Prx is a recently described family of antioxidant enzymes that are highly conserved in eukaryotes and prokaryotes. B. bovis 2-Cys Prx (BbTPx-1) contained two conserved cysteine residues that corresponded to Cys47 and Cys170 of the yeast Prx and the amino acid sequences of two catalytic domains showed significant similarities to those of mammalian typical 2-Cys Prx. The antioxidant activity of the recombinant BbTPx-1 protein expressed in E. coli was demonstrated by a thiol mixed-function oxidation assay. Furthermore, we confirmed that BbTPx-1 was expressed in the cytoplasm of intra-erythrocytic B. bovis merozites. These results suggest that B. bovis likely uses TPx-1 as a way to reduce peroxides as a control of its intracellular redox balance so that it can live and grow in the host cell.