Functional and structural studies of the enzymes related to the NADPH production in trypanosomatids

Abstract

The NADPH acts as the cofactor for enzymes that participate in several processes essential for the cellular homeostasis, like: lipid and cholesterol biosynthesis, production and neutralization of reactive oxygen and nitrogen species. The enzymes glucose-6-phosphate dehydrogenase (G6PDH), 6-phophogluconate dehydrogenase (6PGDH), isocitrate dehydrogenase (IDH) and malic enzyme (ME) are related to the maintenance of the NADPH cellular level. The enzymes G6PDH and 6PGDH belongs to the oxidative branch of the pentose's pathway, while the enzymes IDH and ME oxide the intermediates of the citric acid cycle to reduce the NADP+ to NADPH. Both the enzymes IDH and ME have distinct isoforms, localized in the mitochondrium and cytosol of the parasites. The occurrence of those enzymes in the cytosol represents alternative routes to the NADPH production when cells do not have access to sufficient glucose to sustain a metabolic flux through the pentose´s pathway.The G6PDHs from parasites and humans have being studied at our group already for some years with the purpose to develop new drugs against neglected parasitic diseases, more specifically, trypanosomiasis and leishmaniasis. Recently, we established an collaboration with the research group of Dra. Cristina Nowicki (at the Inst. de Química y Fisicoquímica-biológica da Univ. de Buenos Aires, Argentina) to explore the others NADPH producing enzymes from T. cruzi, more specifically the TcME and TcIDH.The main objectives of this project are: identification of new inhibitors of TcIDH and TCME, crystallographic structure determination of TcIDH and TcME and to map the binding site of new inhibitors in the crystallographic structures of TcIDH and TcME. (AU)