The reductive enzyme thioredoxin 1 acts as an oxidant when it is exported to the
            <i>Escherichia coli</i>
            periplasm

Debarbieux, Laurent; Beckwith, Jon

doi:10.1073/pnas.95.18.10751

Cited by 79 publications

(65 citation statements)

References 48 publications

(64 reference statements)

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“…Previous experiments examining the export of thioredoxin by PhoAss and experiments of Jonda et al in which DsbAss was used were performed with different plasmids and promoters (6,7,11). Therefore, we first verified the previously reported differences in export efficiency by cloning both constructs into derivatives of the same plasmid in which the constructs were under the control of a version of the lac promoter (trc) (see Materials and Methods).…”

Section: Resultsmentioning

confidence: 76%

The DsbA Signal Sequence Directs Efficient, Cotranslational Export of Passenger Proteins to the Escherichia coli Periplasm via the Signal Recognition Particle Pathway

et al. 2003

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The Escherichia coli cytoplasmic protein thioredoxin 1 can be efficiently exported to the periplasmic space by the signal sequence of the DsbA protein (DsbAss) but not by the signal sequence of alkaline phosphatase (PhoA) or maltose binding protein (MBP). Using mutations of the signal recognition particle (SRP) pathway, we found that DsbAss directs thioredoxin 1 to the SRP export pathway. When DsbAss is fused to MBP, MBP also is directed to the SRP pathway. We show directly that the DsbAss-promoted export of MBP is largely cotranslational, in contrast to the mode of MBP export when the native signal sequence is utilized. However, both the export of thioredoxin 1 by DsbAss and the export of DsbA itself are quite sensitive to even the slight inhibition of SecA. These results suggest that SecA may be essential for both the slow posttranslational pathway and the SRP-dependent cotranslational pathway. Finally, probably because of its rapid folding in the cytoplasm, thioredoxin provides, along with gene fusion approaches, a sensitive assay system for signal sequences that utilize the SRP pathway.

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Section: Resultsmentioning

confidence: 76%

The DsbA Signal Sequence Directs Efficient, Cotranslational Export of Passenger Proteins to the Escherichia coli Periplasm via the Signal Recognition Particle Pathway

et al. 2003

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“…The E o Ј ϭ Ϫ249 mV of T. brucei tryparedoxin classifies the parasite protein as a reducing representative, but it should be kept in mind that the in vivo functions of the thiol disulfide oxidoreductases may depend on the redox environment. For E. coli thioredoxin I it was shown that changing the location from cytoplasm to periplasm alters the function of the protein from a reductant to an oxidant (37). The redox potential of tryparedoxin is intermediate between those of E. coli glutaredoxin (Ϫ233 mV) (23) and thioredoxin.…”

Section: Discussionmentioning

confidence: 99%

Catalytic Properties, Thiol p K Value, and Redox Potential of Trypanosoma brucei Tryparedoxin

Reckenfelderbäumer

Krauth‐Siegel

2002

Journal of Biological Chemistry

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The dithiol protein tryparedoxin is a component of the unique trypanothione/trypanothione reductase metabolism of trypanosomatids and is involved in the parasite synthesis of deoxyribonucleotides and the detoxication of hydroperoxides. Tryparedoxin is a highly abundant protein in all life stages of Trypanosoma brucei, the causative agent of African sleeping sickness. As shown here, its functional properties are intermediate between those of classical thioredoxins and glutaredoxins. The redox potential of T. brucei tryparedoxin of ؊249 mV was determined by protein-protein redox equilibration with Escherichia coli thioredoxin. The trypanothione/ tryparedoxin couple is probably the most significant factor determining the cytosolic redox potential of the parasites. The pK value of Cys 40 , the first thiol in the WCPPC motif, is 7.2 as derived from the thiolate absorption at 240 nm and the rate of carboxymethylation. Alteration of the active site into that of thioredoxin (CGPC) did not affect the pK value. In contrast, in the mutant with the glutaredoxin motif (CPYC) the pK dropped to <4.0. The fact that the pK value of tryparedoxin coincides with the intracellular pH of the parasite may contribute to the reactivity of tryparedoxin in thiol disulfide exchange reactions.

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“…To continuously promote oxidation of FlgI, periplasmic thioredoxins or glutaredoxins must themselves be reoxidized by transferring the electrons they receive from FlgI to an electron acceptor. Since DsbB reoxidizes not only its native partner DsbA but also non-native substrates such as thioredoxin 1 and the alpha domain of PDI, we asked whether glutaredoxin 3 is also reoxidized by DsbB (3,4). We tested motility of strains expressing various periplasmic thioredoxins and glutaredoxins in the presence or absence of DsbB (Table 1).…”

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confidence: 99%

Disulfide bond formation by exported glutaredoxin indicates glutathione's presence in the E. coli periplasm

Eser

Masip

Kadokura

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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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 resolved in this compartment. In contrast to the cytoplasm, the periplasm of E. coli is maintained in an oxidized state by DsbA, which is recycled by DsbB. Thioredoxin 1, when exported to the periplasm turns from a disulfide bond reductase to an oxidase that, like DsbA, is dependent on DsbB. In this study we set out to investigate whether a subclass of the thioredoxin superfamily, the glutaredoxins, can become disulfide bond-formation catalysts when they are exported to the periplasm. We find that glutaredoxins can promote disulfide bond formation in the periplasm. However, contrary to the behavior of thioredoxin 1 in this environment, the glutaredoxins do so independently of DsbB. Furthermore, we show that glutaredoxin 3 requires the glutathione biosynthesis pathway for its function and can oxidize substrates with only a single active-site cysteine. Our data provides in vivo evidence suggesting that oxidized glutathione is present in the E. coli periplasm in biologically significant concentrations.protein oxidation ͉ monothiol ͉ SRP

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The reductive enzyme thioredoxin 1 acts as an oxidant when it is exported to the Escherichia coli periplasm

Cited by 79 publications

References 48 publications

The DsbA Signal Sequence Directs Efficient, Cotranslational Export of Passenger Proteins to the Escherichia coli Periplasm via the Signal Recognition Particle Pathway

The DsbA Signal Sequence Directs Efficient, Cotranslational Export of Passenger Proteins to the Escherichia coli Periplasm via the Signal Recognition Particle Pathway

Catalytic Properties, Thiol p K Value, and Redox Potential of Trypanosoma brucei Tryparedoxin

Disulfide bond formation by exported glutaredoxin indicates glutathione's presence in the E. coli periplasm

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