Formation of oxidized (OX) proteins in Entamoeba histolytica exposed to auranofin and consequences on the parasite virulence

Metronidazole (MNZ), the first line drug for amoebiasis and auranofin (AF), an emerging antiprotozoan drug, are both inhibiting Entamoeba histolytica thioredoxin reductase. The nature of oxidised proteins (OXs) formed in AF- or MNZ-treated E. histolytica trophozoites is unknown. In order to fill this knowledge gap, we performed a large-scale identification and quantification of the OXs formed in AF- or MNZ-treated E. histolytica trophozoites using resin-assisted capture coupled to mass spectrometry (MS). We detected 661 OXs in MNZ-treated trophozoites and 583 OXs in AF-treated trophozoites. More than 50% of these OXs were shared, and their functions include hydrolases, enzyme modulators, transferases, nucleic acid binding proteins, oxidoreductases, cytoskeletal proteins, chaperones, and ligases. Here, we report that the formation of actin filaments (F-actin) is impaired in AF-treated trophozoites. Consequently, their erythrophagocytosis, cytopathic activity, and their motility are impaired. We also observed that less than 15% of OXs present in H2 O2 -treated trophozoites are also present in AF- or MNZ-treated trophozoites. These results strongly suggest that the formation of OXs in AF- or MNZ-treated trophozoites and in H2 O2 -treated trophozoites occurred by two different mechanisms.