Thioredoxin linkend metabolism in Entamoeba histolytica

ARIAS, DIEGO; GUTIÉRREZ, CESAR; GUERRERO, SERGIO A.; IGLESIAS, ALBERTO A.

Rosario – Santa Fe - Argentina

Congreso; SAIB - XLII Reunión Anual; 2006

Entamoeba.histolytica, an intestinal parasitic protozoan, is the causative agent of amoebiasis. The parasite usually lives and multiplies within the human gut, under reduced oxygen pressure. During tissue invasion, it is exposed to increased amounts of reactive oxygen species (ROS), which are highly toxic for the parasite. The metabolic pathway used by this organism to cope with such environmental changes is a matter of some controversy. In this work, we present the cloning and expression of the genes ehtrxr and ehtrx41, coding for thioredoxin reductase (TRXR) and thioredoxin (TRX), respectively. The EhTRXR was evaluated in its ability to catalyse the NADPH dependent reduction of DTNB, EhTRX41 and EcTRX. This work strongly supports the occurrence in E. histolytica of a metabolic pathway, the EhTRXR/EhTRX41 system functioning coupled to peroxiredoxin, which was not previously described in the parasite. The redox system could be operative for NADPH-dependent detoxification of ROS, and to metabolize low molecular weight thiols (glutathione and cystine). In addition, it is shown that EcTRX can replace EhTRX41 in this antioxidant system, which might be another tool for coping with the oxidative stress through an association between the parasite and the bacterium. Results add value to the genome and proteome of E. histolytica. Granted by UNL, CAI+D 2006; ANPCyT, PICT´03 01 4733, PAV´03 137