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Disulfide Oxidoreductases (disulfide + oxidoreductase)

Distribution by Scientific Domains

Chemistry	88%

Selected Abstracts

Functional properties of the protein disulfide oxidoreductase from the archaeon Pyrococcus furiosus

FEBS JOURNAL, Issue 16 2004
A member of a novel protein family related to protein disulfide-isomerase
Protein disulfide oxidoreductases are ubiquitous redox enzymes that catalyse dithiol,disulfide exchange reactions with a CXXC sequence motif at their active site. A disulfide oxidoreductase, a highly thermostable protein, was isolated from Pyrococcus furiosus (PfPDO), which is characterized by two redox sites (CXXC) and an unusual molecular mass. Its 3D structure at high resolution suggests that it may be related to the multidomain protein disulfide-isomerase (PDI), which is currently known only in eukaryotes. This work focuses on the functional characterization of PfPDO as well as its relation to the eukaryotic PDIs. Assays of oxidative, reductive, and isomerase activities of PfPDO were performed, which revealed that the archaeal protein not only has oxidative and reductive activity, but also isomerase activity. On the basis of structural data, two single mutants (C35S and C146S) and a double mutant (C35S/C146S) of PfPDO were constructed and analyzed to elucidate the specific roles of the two redox sites. The results indicate that the CPYC site in the C-terminal half of the protein is fundamental to reductive/oxidative activity, whereas isomerase activity requires both active sites. In comparison with PDI, the ATPase activity was tested for PfPDO, which was found to be cation-dependent with a basic pH optimum and an optimum temperature of 90 °C. These results and an investigation on genomic sequence databases indicate that PfPDO may be an ancestor of the eukaryotic PDI and belongs to a novel protein disulfide oxidoreductase family. [source]

Crystallization and preliminary X-ray crystallographic analysis of two dimeric hyperthermostable thioredoxins isolated from Sulfolobus solfataricus

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2009
Alessia Ruggiero
The thioredoxin system of the archaeon Sulfolobus solfataricus involves a number of different proteins: two thioredoxin reductases (SsTrxRB2 and SsTrxRB3), two distinct thioredoxins (SsTrxA1 and SsTrxA2) and a disulfide oxidoreductase (SsPDO). Here, the crystallization and preliminary crystallographic analyses of SsTrxA1 and SsTrxA2, two dimeric proteins endowed with extraordinary thermal stability, are reported. In addition to the functional thioredoxin domain, both SsTrxA1 and SsTrxA2 present an extra N-terminal fragment of approximately 30 residues. Although crystallization trials have been conducted on both forms of the proteins, crystals that were suitable for X-ray crystallographic analyses have only been obtained for their truncated variants. The crystals of SsTrxA2 belonged to space group P2, with unit-cell parameters a = 28.27, b = 27.88, c = 62.06,Å, , = 92.34°, and diffracted to 1.83,Å resolution, whereas the crystals of SsTrxA1 belonged to space group P21, with unit-cell parameters a = 51.76, b = 75.09, c = 55.35,Å, , = 112.64°, and diffracted to 1.90,Å resolution. The structures of the two proteins have been solved by molecular replacement. [source]

Functional properties of the protein disulfide oxidoreductase from the archaeon Pyrococcus furiosus

MBSJ MCC Young Scientist Award 2009 REVIEW: Structural basis of protein disulfide bond generation in the cell

GENES TO CELLS, Issue 9 2010
Kenji Inaba
The formation of protein disulfide bonds is an oxidative reaction that is crucial for the folding and maturation of many secreted and membrane proteins. Both prokaryotic and eukaryotic cells possess various disulfide oxidoreductases and redox-active cofactors to accelerate this oxidative reaction in a correct manner. Crystal or solution structures have been solved for some of the oxidoreductases in the past 10 years, leading to remarkable progress in the field of thiol-based redox cell biology. Consequently, structural and mechanistic similarities in the disulfide bond formation pathways have been uncovered. This review highlights the molecular basis of the elaborate oxidative systems operating in the Escherichia coli periplasm, the endoplasmic reticulum lumen and the mitochondrial intermembrane space. The accumulated knowledge provides important insights into how protein and redox homeostasis are maintained in the cell. [source]

Crystal structures of oxidized and reduced forms of human mitochondrial thioredoxin 2

PROTEIN SCIENCE, Issue 10 2005
Aude Smeets
ASK1, apoptosis signal-regulating kinase 1; TXN, thioredoxin; hTXN1, human cytosolic/nuclear thioredoxin 1; hTXN2, human mitochondrial thioredoxin 2; hPRDX5, human peroxiredoxin 5. Gene symbols in this article follow standard nomenclature defined by the Human Genome Organization Nomenclature Committee (http://www.gene.ucl.ac.uk/nomenclature/). For this reason TXN is used instead of the commonly used Trx for designating thioredoxin in the literature. Abstract Mammalian thioredoxin 2 is a mitochondrial isoform of highly evolutionary conserved thioredoxins. Thioredoxins are small ubiquitous protein,disulfide oxidoreductases implicated in a large variety of biological functions. In mammals, thioredoxin 2 is encoded by a nuclear gene and is targeted to mitochondria by a N-terminal mitochondrial presequence. Recently, mitochondrial thioredoxin 2 was shown to interact with components of the mitochondrial respiratory chain and to play a role in the control of mitochondrial membrane potential, regulating mitochondrial apoptosis signaling pathway. Here we report the first crystal structures of a mammalian mitochondrial thioredoxin 2. Crystal forms of reduced and oxidized human thioredoxin 2 are described at 2.0 and 1.8 Å resolution. Though the folding is rather similar to that of human cytosolic/nuclear thioredoxin 1, important differences are observed during the transition between the oxidized and the reduced states of human thioredoxin 2, compared with human thioredoxin 1. In spite of the absence of the Cys residue implicated in dimer formation in human thioredoxin 1, dimerization still occurs in the crystal structure of human thioredoxin 2, mainly mediated by hydrophobic contacts, and the dimers are associated to form two-dimensional polymers. Interestingly, the structure of human thioredoxin 2 reveals possible interaction domains with human peroxiredoxin 5, a substrate protein of human thioredoxin 2 in mitochondria. [source]

Genomic-scale comparison of sequence- and structure-based methods of function prediction: Does structure provide additional insight?

PROTEIN SCIENCE, Issue 5 2001
Jacquelyn S. Fetrow
Abstract A function annotation method using the sequence-to-structure-to-function paradigm is applied to the identification of all disulfide oxidoreductases in the Saccharomyces cerevisiae genome. The method identifies 27 sequences as potential disulfide oxidoreductases. All previously known thioredoxins, glutaredoxins, and disulfide isomerases are correctly identified. Three of the 27 predictions are probable false-positives. Three novel predictions, which subsequently have been experimentally validated, are presented. Two additional novel predictions suggest a disulfide oxidoreductase regulatory mechanism for two subunits (OST3 and OST6) of the yeast oligosaccharyltransferase complex. Based on homology, this prediction can be extended to a potential tumor suppressor gene, N33, in humans, whose biochemical function was not previously known. Attempts to obtain a folded, active N33 construct to test the prediction were unsuccessful. The results show that structure prediction coupled with biochemically relevant structural motifs is a powerful method for the function annotation of genome sequences and can provide more detailed, robust predictions than function prediction methods that rely on sequence comparison alone. [source]

The structure of the periplasmic thiol,disulfide oxidoreductase SoxS from Paracoccus pantotrophus indicates a triple Trx/Grx/DsbC functionality in chemotrophic sulfur oxidation

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2009
Yvonne Carius
The periplasmic thiol,disulfide oxidoreductase SoxS is beneficial for the sulfur-oxidizing (Sox) phenotype of the facultative chemotrophic bacterium Paracoccus pantotrophus and is not part of the Sox enzyme system. SoxS combines features of thioredoxins, glutaredoxins and the thiol,disulfide oxidoreductases of the Dsb family in structure, target specificity and reaction. The structure of SoxS was solved in oxidized and reduced forms at 2.1 and 1.9,Å resolution, respectively. SoxS revealed high structural homology to typical cytoplasmic bacterial thioredoxins. In contrast, SoxS contained the active-site motif Pro-Gly-Cys-Leu-Tyr-Cys that is not present in other thioredoxins. Interestingly, the sequence of this motif is closely related to the Pro-Gly-Cys-Pro-Tyr-Cys sequence of some glutaredoxins and to the Pro-Xaa-Cys-Xaa-Tyr-Cys sequences of some members of the DsbC and DsbG subfamilies of thiol,disulfide oxidoreductases. Furthermore, the proposed substrate of SoxS, the interprotein disulfide of SoxY, Cys110Y,Cys110Y, is structurally similar to oxidized glutathione. However, SoxS is proposed to specifically reduce the interprotein disulfide between two SoxY subunits, releasing a heterodimeric SoxYZ as an active part of the sulfur-oxidation cycle. [source]