Organisms have evolved elaborate systems that ensure the homeostasis of the thiol redox environment in their intracellular compartments. In Escherichia coli, the cytoplasm is kept under reducing conditions by the thioredoxins with the help of thioredoxin reductase and the glutaredoxins with the small molecule glutathione and glutathione reductase. As a result, disulfide bonds are constantly res...

Platyhelminth parasites are a major health problem in developing countries. In contrast to their mammalian hosts, platyhelminth thiol-disulfide redox homeostasis relies on linked thioredoxin-glutathione systems, which are fully dependent on thioredoxin-glutathione reductase (TGR), a promising drug target. TGR is a homodimeric enzyme comprising a glutaredoxin domain and thioredoxin reductase (TR...

In most organisms, thioredoxin (Trx) and/or glutathione (GSH) systems are essential for redox homeostasis and deoxyribonucleotide synthesis. Platyhelminth parasites have a unique and simplified thiol-based redox system, in which the selenoprotein thioredoxin-glutathione reductase (TGR), a fusion of a glutaredoxin (Grx) domain to canonical thioredoxin reductase domains, is the sole enzyme supply...

The so-called thioredoxin system, thioredoxin (Trx), thioredoxin reductase (Trr), and NADPH, acts as a disulfide reductase system and can protect cells against oxidative stress. In Saccharomyces cerevisiae, two thioredoxins (Trx1 and Trx2) and one thioredoxin reductase (Trr1) have been characterized, all of them located in the cytoplasm. We have identified and characterized a novel thioredoxin ...

IscA is a key member of the iron-sulfur cluster assembly machinery found in bacteria and eukaryotes. Previously, IscA was characterized as an alternative iron-sulfur cluster assembly scaffold, as purified IscA can host transient iron-sulfur clusters. However, recent studies indicated that IscA is an iron-binding protein that can provide iron for the iron-sulfur cluster assembly in a proposed sc...

Metronidazole, a 5-nitroimidazole drug, has been the gold standard for several decades in the treatment of infections with microaerophilic protist parasites, including Entamoeba histolytica. For activation, the drug must be chemically reduced, but little is known about the targets of the active metabolites. Applying two-dimensional gel electrophoresis and mass spectrometry, we searched for prot...

Purified calf thymus ribonucleoside-diphosphate reductase (2'-deoxyribonucleoside-diphosphate:oxidized-thioredoxin 2'-oxidoreductase, EC 1.17.4.1), showed an absolute requirement for a dithiol as hydrogen donor, whereas the natural monothiol glutathione (GSH) was inactive per se. However, a protein partially purified from thymus coupled the oxidation of GSH to the formation of deoxyribonucleoti...

The crystal structures of three forms of Escherichia coli thioredoxin reductase have been refined: the oxidized form of the wild-type enzyme at 2.1 A resolution, a variant containing a cysteine to serine mutation at the active site (Cys138Ser) at 2.0 A resolution, and a complex of this variant with nicotinamide adenine dinucleotide phosphate (NADP+) at 2.3 A resolution. The enzyme mechanism inv...

The thioredoxin system, comprising thioredoxin (Trx), thioredoxin reductase (TrxR) and NADPH, is one of the major cellular antioxidant systems, implicated in a large and growing number of biological functions. Trx acts as an oxidoreductase via a highly conserved dithiol/disulfide motif located in the active site ( Trp-Cys-Gly-Pro- Cys-Lys-). Different factors are involved in the regulation of T...