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Type: Artigo de periódico
Title: Leishmania infantum: Provision of reducing equivalents to the mitochondrial tryparedoxin/tryparedoxin peroxidase system
Author: Castro, H
Romao, S
Gadelha, FR
Tomas, AM
Abstract: Within the mitochondrion of Leishmania infantum, hydroperoxide metabolism relies on the activity of tryparedoxin-dependent peroxidases (TXNPxs). Tryparedoxins (TXNs) are thioredoxin-related oxidoreductases, which in vitro are reduced by the trypanothione reductase/trypanothione [TR/T(SH)(2)] redox couple. Still, there is no evidence that this actually occurs in the mitochondrion. This communication addresses the question of how the mitochondrial TXN/TXNPx system is reduced. First, using a digitonin fractionation assay, we show that TR activity is absent from the L. infantum mitochondrion. The possibility that this organelle possesses alternative electron sources for TXN/TXNPx is then investigated. Biochemical assays performed with purified recombinant enzymes, revealed that TR and T(SH)(2) can be replaced, albeit less efficiently, by the dihydrolipoamide dehydrogenase/lipoamide redox system as TXN/TXNPx electron donor. This result challenges the classical view that T(SH)(2) is the only reductant for TXNs and add new prospects regarding the involvement of 2-oxo acid dehydrogenase complexes in L. infantum mitochondrial hydroperoxide metabolism. (C) 2008 Elsevier Inc. All rights reserved,
Subject: Leishmania
Trypanothione reductase
Dihydrolipoamide dehydrogenase
Trypanosoma brucei, Trypanosoma cruzi, Leishmania spp., trypanosomatids
Country: EUA
Editor: Academic Press Inc Elsevier Science
Rights: fechado
Identifier DOI: 10.1016/j.exppara.2008.09.002
Date Issue: 2008
Appears in Collections:Unicamp - Artigos e Outros Documentos

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