Disease relevance of trxB

• Recombinant peroxiredoxin (FhePrx) prevented metal-catalyzed oxidative nicking of plasmid DNA and detoxified hydrogen peroxide when coupled with Escherichia coli thioredoxin and thioredoxin reductase (k(cat)/K(m)=5.2x10(5)M(-1)s(-1)) [1].
• We used this strain to select f1 phage which contain a cloned trxB gene [2].
• Purification and functional analysis of the Mycobacterium leprae thioredoxin/thioredoxin reductase hybrid protein [3].
• Anabaena thioredoxin-S2 is a good substrate for E. coli thioredoxin reductase [4].
• The structure of AhpF from Salmonella typhimurium at 2.0 A resolution, determined using multiwavelength anomalous dispersion, shows that the C-terminal portion of AhpF (residues 210-521) is structurally like Escherichia coli thioredoxin reductase [5].

High impact information on trxB

• In thioredoxin reductase (TrxR) from Escherichia coli, cycles of reduction and reoxidation of the flavin adenine dinucleotide (FAD) cofactor depend on rate-limiting rearrangements of the FAD and NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) domains [6].
• Our results suggest that the activity responsible for disulfide bond formation in trxB mutants acts at the post-translational level and is able to freely diffuse within inclusion bodies [7].
• Overproduction of the dnaKJ operon in trxB cells decreased the formation of disulfide-bonded SPARC multimers in the aggregated material but not in its soluble counterpart [7].
• However, mutants in which the reduction of both thioredoxins and glutathione is impaired (trxB gor mutants) accumulate oxidized, enzymatically active alkaline phosphatase in the cytoplasm [8].
• Thioredoxin is a small (Mr 12,000) ubiquitous redox protein with the conserved active site structure: -Trp-Cys-Gly-Pro-Cys-. The oxidized form (Trx-S2) contains a disulfide bridge which is reduced by NADPH and thioredoxin reductase; the reduced form [Trx(SH)2] is a powerful protein disulfide oxidoreductase [9].

Chemical compound and disease context of trxB

• The redox protein and thioredoxin reductase retained their full activities for over 1h at 100 degrees C. The redox potential of the redox protein was similar to that of thioredoxin from E. coli and lower than that of glutathione [10].
• In this study, a gene containing the coding region for Atlantic salmon (Salmo salar) IGF-II was cloned into a modified pET32a expression vector and transformed into Escherichia coli BL21 trxB (DE3) cells [11].
• Oxidation-reduction properties of Escherichia coli thioredoxin reductase altered at each active site cysteine residue [12].
• The oxidation-reduction active group of both thioredoxins consists of a single cystine residue which is reduced to sulfhydryl form by NADPH in the presence of E. coli thioredoxin reductase [13].
• Functional assays showed that the protein has thioredoxin activity; it can act as a substrate for E. coli thioredoxin reductase and also catalyse the reduction of insulin by dithiothreitol [14].

Biological context of trxB

• In silico analysis of the D. desulfuricans genome revealed the presence of thioredoxin 1 (dstrx1), thioredoxin 2 (dstrx2) and thioredoxin reductase (dstrxR) genes [15].
• Furthermore, in anaerobiosis, E. coli is dependent for growth on class III RNR, NrdDG, and on having at least one of the two reductive systems, thioredoxin reductase or glutathione reductase [16].
• We show here that export by the Tat translocator is dependent upon oxidative protein folding in the cytoplasm of trxB gor cells prior to transport [17].
• The predicted amino acid sequence of trxB contained 315 residues with a conserved NADPH binding domain and FAD binding domains I and II [18].
• The complete nucleotide sequence of the ClaI-HindIII fragment reveals three open reading frames, one being trxB (19.3 min on the E. coli chromosome map, encoding thioredoxin reductase), confirming the mapping position of cydD previously established by P1-mediated transduction [19].

Anatomical context of trxB

• PhoA degradation was reduced in a thioredoxin-reductase mutant (trxB), which allowed PhoADelta2-22 to fold into an active form in the cytosol [20].
• Even when such proteins are secreted into the oxidizing periplasm or expressed in the cytoplasm of cells carrying mutations in the major intracellular disulfide bond reduction systems (e.g., trxB gor mutants), correct folding can be problematic unless a folding modulator is simultaneously coexpressed [17].
• Recently, we showed that in Escherichia coli trxB gor mutants, in which the reduction of thioredoxin and glutathione is impaired, the redox potential of the cytoplasm becomes comparable to that of the mammalian endoplasmic reticulum, thus allowing the formation of disulfide bonds in certain complex proteins (P [21].
• The rate of the oxygen-dependent reaction between calf thymus thioredoxin reductase and GS-Se-SG was increased 2-fold in the presence of 4 mM GSH, indicating that HSe- was the reactive intermediate [22].
• Enzyme-dependent ascorbate recycling in human erythrocytes: role of thioredoxin reductase [23].

Associations of trxB with chemical compounds

• Exogenously provided dithiothreitol rescued the kdp expression defect in trxB but not trxA mutants [24].
• Reduced kdp expression was observed even in a trxB strain that harbored a variant KdpD polypeptide bearing no Cys residues [24].
• In addition, the use of the trxB mutant also enhanced the expression level of tandem multimers, which contain two cysteine residues at both ends of the monomeric unit [25].
• Thioredoxin reductase contains a redox active disulfide and is a member of the pyridine nucleotide-disulfide oxidoreductase family of flavoenzymes that includes lipoamide dehydrogenase, glutathione reductase, trypanothione reductase, mercuric reductase, and NADH peroxidase [26].
• W28A Trx-S2 is a good substrate for thioredoxin reductase, and W28A Trx-(SH)2 is as efficient as wild-type protein in reduction of insulin disulfides [27].

Other interactions of trxB

• However, in the absence of thioredoxin reductase and NrdH, glutaredoxin 1 can partially replace NrdH [16].

Analytical, diagnostic and therapeutic context of trxB

• Crystallization and preliminary x-ray characterization of thioredoxin reductase from Escherichia coli [28].
• In order to assess the catalytic role of each nascent thiol of the active site disulfide of thioredoxin reductase, the 2 cysteines (Cys-136 and Cys-139) forming this disulfide have been individually changed to serines by site-directed mutageneses of the cloned trxB gene of Escherichia coli [29].
• An equimolar mixture of thioredoxin-T-(1-73) and thioredoxin-T-(74-108) showed full immunoprecipitation activity with antithioredoxin and significant enzymatic activity with thioredoxin reductase [30].
• The total quantity of thioredoxin was determined by rocket immunoelectrophoresis and the amount of thioredoxin-S2 was measured by its enzymatic activity with thioredoxin reductase [31].
• The conformational dynamics of wild-type Escherichia coli thioredoxin reductase (TrxR) and the mutant enzyme C138S were studied by ultrafast time-resolved fluorescence of the flavin cofactor in combination with circular dichroism (both in the flavin fingerprint and far-UV regions) and steady-state fluorescence and absorption spectroscopy [32].

References