Comunicación oral - "Functional characterization of atypical thioredoxins from Entamoeba histolytica."

ARIAS DG; BIROCCO, F; SASONI N; GUERRERO, SA; IGLESIAS, AA

Paraná

Congreso; SAIB LIV Reunión Anual; 2018

SAIB

Entamoeba histolytica, aunicellular parasite, usually lives and multiplies within the human gut, underreduced oxygen pressure. During tissue invasion, it is exposed to increasedamounts of reactive oxygen species, which are highly toxic for the parasite.The metabolic pathways used by this organism to cope with such environmentalchanges and redox homeostasis are a matter of our work. Recently, wecharacterized in E. histolytica its functional thioredoxinssystem, composed by thioredoxins (TRXs) and thioredoxin reductase (TRXR). Inthis work, we present the functional characterization of three atypical TRXfrom E. histolytica (EhTRX111, EhTRX212 and EhTRX289). EhTRX111(a tail-anchor protein) and EhTRX289, but not EhTRX212, were able to in vitro reduction(via EhTRXR) of cystine, CySNO, insulin and Eh2CysPrx. However, EhTRX212 was able tocoordinate iron-sulfur cluster (ISC) by an in vitroreconstitution assay. By gel filtration chromatography and UV-Vis spectroscopyexperiments were detected EhTRX212-ISC complexes. In otherhands, we observed the nitrosation CySNO-dependent of EhTRXs. This redox modification generated a partiallyreversible inactivation of the disulfide reductase activity of these proteins.This suggests that this modification could act as a possible regulation oftheir activity. This work strongly supports the occurrence in E.histolytica of new TRXs, which were not previously described in theparasite. Our results extend the knowledge regarding to EhTRX function and suggest that these proteins haveimportant functions in redox and iron metabolism of this pathogen parasite.