scholarly journals Unraveling the Redox Properties of the Global Regulator FurA fromAnabaenasp. PCC 7120: Disulfide Reductase Activity Based on Its CXXC Motifs

2014 ◽  
Vol 20 (9) ◽  
pp. 1396-1406 ◽  
Author(s):  
Laura Botello-Morte ◽  
M. Teresa Bes ◽  
Begoña Heras ◽  
Ángela Fernández-Otal ◽  
M. Luisa Peleato ◽  
...  
Keyword(s):  
Reductase Activity ◽  
Redox Properties ◽  
Global Regulator ◽  
Disulfide Reductase ◽  
Pcc 7120

scholarly journals Mitochondrial Thioredoxin-Glutathione Reductase from LarvalTaenia crassiceps(Cysticerci)

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Alberto Guevara-Flores ◽  
Irene P. del Arenal ◽  
Guillermo Mendoza-Hernández ◽  
Juan Pablo Pardo ◽  
Oscar Flores-Herrera ◽  
...  
Keyword(s):  
Glutathione Reductase ◽  
Reductase Activity ◽  
Catalytic Efficiency ◽  
Dependent Manner ◽  
Exchange Reactions ◽  
Disulfide Exchange ◽  
Oxidative Inactivation ◽  
Disulfide Reductase ◽  
Thioredoxin Peroxidase ◽  
Thioredoxin Glutathione Reductase

Mitochondrial thioredoxin-glutathione reductase was purified from larvalTaenia crassiceps(cysticerci). The preparation showed NADPH-dependent reductase activity with either thioredoxin or GSSG, and was able to perform thiol/disulfide exchange reactions. At25∘Cspecific activities were437  ±  27mU mg-1and840  ±  49mU mg-1with thioredoxin and GSSG, respectively. ApparentKmvalues were0.87  ±  0.04 μM,41  ±  6 μM and19  ±  10 μM for thioredoxin, GSSG and NADPH, respectively. Thioredoxin from eukaryotic sources was accepted as substrate. The enzyme reduced H2O2in a NADPH-dependent manner, although with low catalytic efficiency. In the presence of thioredoxin, mitochondrial TGR showed a thioredoxin peroxidase-like activity. All disulfide reductase activities were inhibited by auranofin, suggesting mTGR is dependent on selenocysteine. The reductase activity with GSSG showed a higher dependence on temperature as compared with the DTNB reductase activity. The variation of the GSSG- and DTNB reductase activities on pH was dependent on the disulfide substrate. Like the cytosolic isoform, mTGR showed a hysteretic kinetic behavior at moderate or high GSSG concentrations, but it was less sensitive to calcium. The enzyme was able to protect glutamine synthetase from oxidative inactivation, suggesting that mTGR is competent to contend with oxidative stress.

scholarly journals The Archaeon Methanosarcina acetivorans Contains a Protein Disulfide Reductase with an Iron-Sulfur Cluster

2007 ◽  
Vol 189 (20) ◽  
pp. 7475-7484 ◽  
Author(s):  
Daniel J. Lessner ◽  
James G. Ferry
Keyword(s):  
Aromatic Compounds ◽  
Stress Proteins ◽  
Reductase Activity ◽  
Strictly Anaerobic ◽  
Methanosarcina Acetivorans ◽  
Gene Encoding ◽  
Iron Sulfur Cluster ◽  
Disulfide Reductase ◽  
Regulate Protein ◽  
Protein Disulfide

ABSTRACT Methanosarcina acetivorans, a strictly anaerobic methane-producing species belonging to the domain Archaea, contains a gene cluster annotated with homologs encoding oxidative stress proteins. One of the genes (MA3736) is annotated as a gene encoding an uncharacterized carboxymuconolactone decarboxylase, an enzyme required for aerobic growth with aromatic compounds by species in the domain Bacteria. Methane-producing species are not known to utilize aromatic compounds, suggesting that MA3736 is incorrectly annotated. The product of MA3736, overproduced in Escherichia coli, had protein disulfide reductase activity dependent on a C67XXC70 motif not found in carboxymuconolactone decarboxylase. We propose that MA3736 be renamed mdrA (methanosarcina disulfide reductase). Further, unlike carboxymuconolactone decarboxylase, MdrA contained an Fe-S cluster. Binding of the Fe-S cluster was dependent on essential cysteines C67 and C70, while cysteines C39 and C107 were not required. Loss of the Fe-S cluster resulted in conversion of MdrA from an inactive hexamer to a trimer with protein disulfide reductase activity. The data suggest that MdrA is the prototype of a previously unrecognized protein disulfide reductase family which contains an intermolecular Fe-S cluster that controls oligomerization as a mechanism to regulate protein disulfide reductase activity.

scholarly journals Identification of Multiple Soluble Fe(III) Reductases in Gram-Positive Thermophilic BacteriumThermoanaerobacter indiensisBSB-33

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Subrata Pal
Keyword(s):  
Reductase Activity ◽  
Three Dimensional ◽  
Thioredoxin Reductase ◽  
Desulfovibrio Desulfuricans ◽  
Structural Similarity ◽  
Thermophilic Bacterium ◽  
Gram Positive ◽  
Reduction Activity ◽  
Structural Identity ◽  
Disulfide Reductase

Thermoanaerobacter indiensisBSB-33 has been earlier shown to reduce Fe(III) and Cr(VI) anaerobically at 60°C optimally. Further, the Gram-positive thermophilic bacterium contains Cr(VI) reduction activity in both the membrane and cytoplasm. The soluble fraction prepared fromT. indiensiscells grown at 60°C was found to contain the majority of Fe(III) reduction activity of the microorganism and produced four distinct bands in nondenaturing Fe(III) reductase activity gel. Proteins from each of these bands were partially purified by chromatography and identified by mass spectrometry (MS) with the help ofT. indiensisproteome sequences. Two paralogous dihydrolipoamide dehydrogenases (LPDs), thioredoxin reductase (Trx), NADP(H)-nitrite reductase (Ntr), and thioredoxin disulfide reductase (Tdr) were determined to be responsible for Fe(III) reductase activity. Amino acid sequence and three-dimensional (3D) structural similarity analyses of theT. indiensisFe(III) reductases were carried out with Cr(VI) reducing proteins from other bacteria. The two LPDs and Tdr showed very significant sequence and structural identity, respectively, with Cr(VI) reducing dihydrolipoamide dehydrogenase fromThermus scotoductusand thioredoxin disulfide reductase fromDesulfovibrio desulfuricans. It appears that in addition to their iron reducing activityT. indiensisLPDs and Tdr are possibly involved in Cr(VI) reduction as well.

Peroxiredoxin 2 functions as a noncatalytic scavenger of low-level hydrogen peroxide in the erythrocyte

Blood ◽  
2006 ◽  
Vol 109 (6) ◽  
pp. 2611-2617 ◽  
Author(s):  
Felicia M. Low ◽  
Mark B. Hampton ◽  
Alexander V. Peskin ◽  
Christine C. Winterbourn
Keyword(s):  
Sulfonic Acid ◽  
Reductase Activity ◽  
Thioredoxin Reductase ◽  
Redox Properties ◽  
High Concentration ◽  
Knock Out ◽  
Peroxiredoxin 2 ◽  
The Third ◽  
Minute Period ◽  
Knock Out Mice

AbstractPeroxiredoxin 2 (Prx2), a thiol-dependent peroxidase, is the third most abundant protein in the erythrocyte, and its absence in knock-out mice gives rise to hemolytic anemia. We have found that in human erythrocytes, Prx2 was extremely sensitive to oxidation by H2O2, as dimerization was observed after exposure of 5 × 106 cells/mL to 0.5 μM H2O2. In contrast to Prx2 in Jurkat T lymphocytes, Prx2 was resistant to overoxidation (oxidation of the cysteine thiol to a sulfinic/sulfonic acid) in erythrocytes. Reduction of dimerized Prx2 in the erythrocyte occurred very slowly, with reversal occurring gradually over a 20-minute period. Very low thioredoxin reductase activity was detected in hemolysates. We postulate that this limits the rate of Prx2 regeneration, and this inefficiency in recycling prevents the overoxidation of Prx2. We also found that Prx2 was oxidized by endogenously generated H2O2, which was mainly derived from hemoglobin autoxidation. Our results demonstrate that in the erythrocyte Prx2 is extremely efficient at scavenging H2O2 noncatalytically. Although it does not act as a classical antioxidant enzyme, its high concentration and substrate sensitivity enable it to handle low H2O2 concentrations efficiently. These unique redox properties may account for its nonredundant role in erythrocyte defense against oxidative stress.

scholarly journals Identification of three novel antisense RNAs in the fur locus from unicellular cyanobacteria

Microbiology ◽  
2011 ◽  
Vol 157 (12) ◽  
pp. 3398-3404 ◽  
Author(s):  
Emma Sevilla ◽  
Beatriz Martín-Luna ◽  
Andrés González ◽  
Jesús A. Gonzalo-Asensio ◽  
María Luisa Peleato ◽  
...  
Keyword(s):  
Transcriptional Analysis ◽  
Filamentous Cyanobacterium ◽  
Ferric Uptake Regulator ◽  
Global Regulator ◽  
Antisense Rnas ◽  
Non Coding Rnas ◽  
Regulatory Loop ◽  
Pcc 7120 ◽  
Overlapping Transcripts ◽  
Regulatory Connection

The interplay between Fur (ferric uptake regulator) proteins and small, non-coding RNAs has been described as a key regulatory loop in several bacteria. In the filamentous cyanobacterium Anabaena sp. PCC 7120, a large dicistronic transcript encoding the putative membrane protein Alr1690 and an α-furA RNA is involved in the modulation of the global regulator FurA. In this work we report the existence of three novel antisense RNAs in cyanobacteria and show that a cis α-furA RNA is conserved in very different genomic contexts, namely in the unicellular cyanobacteria Microcystis aeruginosa PCC 7806 and Synechocystis sp. PCC 6803. Syα-fur RNA covers only part of the coding sequence of the fur orthologue sll0567, whose flanking genes encode two hypothetical proteins. Transcriptional analysis of fur and its adjacent genes in Microcystis unravels a highly compact organization of this locus involving overlapping transcripts. Maα-fur RNA spans the whole Mafur CDS and part of the flanking dnaJ and sufE sequences. In addition, Mafur seems to be part of a dicistronic operon encoding this regulator and an α-sufE RNA. These results allow new insights into the transcriptomes of two unicellular cyanobacteria and suggest that in M. aeruginosa PCC 7806, the α-fur and α-sufE RNAs might participate in a regulatory connection between the genes of the dnaJ–fur–sufE locus.

scholarly journals Expression of ferredoxin-NADP+ reductase in heterocysts from Anabaena sp

1996 ◽  
Vol 316 (1) ◽  
pp. 157-160 ◽  
Author(s):  
Pedro RAZQUIN ◽  
Maria F. FILLAT ◽  
Stefan SCHMITZ ◽  
Olaf STRICKER ◽  
Herbert BÖHME ◽  
...  
Keyword(s):  
Reductase Activity ◽  
Regulatory Factor ◽  
Vegetative Cells ◽  
Combined Nitrogen ◽  
Anabaena Pcc 7120 ◽  
Fnr Protein ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Genomic Map

The expression of ferredoxin–NADP+ reductase (FNR) from Anabaena sp. PCC 7119 in heterocysts and vegetative cells has been quantified. Specific reductase activity in heterocysts was approximately 10 times higher than in vegetative cells, corresponding to the increased FNR protein content. This was confirmed by immunoquantification of the FNR protein from whole filaments of Anabaena sp. PCC 7120 grown in media with and without combined nitrogen. Transcription of the petH gene was markedly enhanced in the absence of combined nitrogen. This suggests that the increased RNA level is mainly responsible for the up-regulation of FNR in heterocysts. As has been observed for nif genes, iron deficiency also increased transcription of petH. Characterization of the FNR purified from isolated heterocysts showed no detectable differences from the enzyme from vegetative cells. Although nitrogen stress was a key regulatory factor, localization of the petH gene in the genomic map of Anabaena PCC 7120 showed that this gene is not physically associated with the nif cluster.

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