Identification and functional analysis of a novel mitochondria-localized 2-Cys peroxiredoxin, BbTPx-2, from Babesia bovis

Cysteine-based peroxidases, known as peroxiredoxins (Prx) or thioredoxin peroxidases (TPx), are important antioxidant enzymes that prevent oxidative damage caused by reactive oxygen species (ROS). In this study, we identified a novel mitochondrial 2-Cys Prx, BbTPx-2, from a bovine Babesia parasite, B. bovis. BbTPx-2 complementary DNA (cDNA) encodes a polypeptide of 254 amino acid residues. This protein has a mitochondrial targeting peptide at the N-terminus and two conserved cysteine residues of the typical 2-Cys Prx. By using a thiol mixed-function oxidation assay, the antioxidant activity of recombinant BbTPx-2 was revealed, and its antioxidant activity was comparable to that of a cytosolic 2-Cys Prx from B. bovis, BbTPx-1. Notably, we confirmed that BbTPx-2 was expressed in the mitochondrion of B. bovis merozoites. Taken together, the results suggest that the mitochondrial BbTPx-2 is an antioxidative enzyme for scavenging ROS in B. bovis.