REDOX-DEPENDANT STRUCTURAL MODIFICATIONS OF tHE SCHISTOSOMA MANSONI GLUTATHIONE STRANSFERASE OMEGA

AMIRANTE A.; GIRARDINI J.E.; SERRA E.

Bariloche, Argentina

Congreso; XXXIX Reunión Anual de la Sociedad Argentina de Bioquímica y Biología molecular - SAIB; 2003

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.1pt 792.1pt; margin:36.0pt 328.4pt 36.0pt 36.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The gluthatione S-transferases (GSTs) playa key role in phase II of enzymic detoxification of a wide variety of both endogenous and exogenous electrophilic compounds. GSTs are considered the most prominent detoxifying enzymes in helminths. We have c10ned an Omega c1ass GST gene from Schistosoma mansoni (SmGSTO). The recombinant enzyme shown glutathione-dependent dehydroascorbate reductase, and thiol transferase activities; but low activity towards the c1assical substrate, CDNB. Spectroscopic experiments showed a structural modification ofthe enzyme related to its redox state. Re­duced form ofthe enzyme is monomeric. In contrast, in presence of GSSG the enzyme partially dimmerized. The dimmer can be monomerized by DTT or GSH, suggesting the existence of a disul­fide bond. The enzyme was able to bind to S-hexyl glutathione aga­rose, only in its reduced state. Westem Blot experiments performed with total protein extracts of adult parasites, cultured under normal or stress conditions (cumene hydroperoxide and hydrogen perox­ide), shown that SmGSTO is in its monomer oxidized state. We also observed a greater expression of SmGSTO in male than in female. Immunohistochemistry assays showed that tissues with mayor ex­pression are, intestinal parenchyma, and tegument (inc1uding spines and tuberc1es) exposed to the media. We could not detect SmGSTO neither in ovary nor in testis.