Expression of mRNAs and proteins for peroxiredoxins in Plasmodium falciparum erythrocytic stage

mRNA and protein expression profiles for three peroxiredoxins (PfTPx-1, PfTPx-2 and Pf1-Cys-Prx) and a thioredoxin (PfTrx-1) of Plasmodium falciparum during the erythrocytic stage were examined by real-time quantitative reverse transcription-PCR (RT-PCR), Western blotting and confocal laser scanning microscopy. PfTPx-1 was expressed constitutively in the parasite cytoplasm throughout the erythrocytic stage, suggesting a housekeeping role of this enzyme for control of intercellular reactive oxygen species (ROS) in the parasite. Pf1-Cys-Prx showed elevated expression during the trophozoite and early schizont stages in the parasite cytoplasm, and this profile suggested that this peroxiredoxin (Prx) detoxifies metabolism-derived ROS such as those released from heme iron. The other 2-Cys Prx, PfTPx-2, was detected in mitochondria and was expressed in both the trophozoite and schizont stages. Detection of the Prx in mitochondria is consistent with recent reports of the existence of a respiratory chain, which produces ROS, in the mitochondria of P. falciparum. PfTrx-1 showed elevated expression during the trophozoite and schizont stages in the parasite cytoplasm. Finally, expression of these antioxidant protein genes is most likely regulated at the transcriptional level because their mRNA and protein expression profiles overlapped.