A MULTIDOMAIN GLUTATHIONE-S-TRANSFERASE OF Trypanosoma cruzi: BIOCHEMICAL AND CELLULAR CHARACTERIZATION

NATALIA SASONI; SERGIO A. GUERRERO; ALBERTO A. IGLESIAS; DIEGO G. ARIAS

Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

Glutathione-S-transferase(GST), a member of the Trx family, has the ability to conjugate glutathione(GSH) to different molecules (such as pharmaceuticals) to make them easilyexcreted. According with this, it has been previously reported that GST in Plasmodium falciparum is important forantiparasitic neutralization. Therefore, the study of this enzyme could beinteresting in anti-Chagas disease drugs design. This disease is caused by theprotozoan parasite Trypanosoma cruzi.In this work, we present an isoform of GST identified in the genome of T. cruzi which has signal peptide, a glutaredoxin(Grx) domain and a prostaglandin E synthase domain. The recombinant enzyme wasobtained and GST activity was measured by following the increase of absorbanceat 340 nm, which result from the conjugation between GSH and the1-chloro-2,4-dinitrobenzene. The reaction was optimal at pH range from 7 to 9and not followed Michaelis-Menten kinetics. However, no Grx function wasdetected for the enzyme. On the other hand, by a western blotting assay ahigher cellular abundance of the protein was detected in vector life stages(metacyclic trypomastigote and epimastigote) than in the mammalian host. Bycell fractionation with CaCl2 and NaCO3 (pH 11.0), it wasdemonstrated that the enzyme is a membrane protein and has no mitochondriallocalization. The association to membrane of TcGST could be promoted by a mechanism of palmitoylation. Thismechanism is a reversible lipid modification in which one or more cysteinethiols on a protein are modified to form a thioester with a palmitoyl group.Through an in silico assay weidentified that the protein has a high probability to be modified with apalmitoyl group. This induces us to continue studying this protein which apparentlyperform extensive functions in the cellular metabolism of T. cruzi.