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Protein folding

Where do the electrons go?

Nature volume 401, pages 30–31 (1999)Cite this article

Can DsbB — which lacks cofactors such as haems or flavins — be oxidized directly by oxygen? The answer came from an intriguing observation. When a DsbB preparation was purified from 97% to more than 99% purity, the enzyme lost its ability to catalyse the oxidation of DsbA by molecular oxygen in vitro. But this pure DsbB then provided an assay for identifying the crucial components of the inner membrane that had been removed during the final purification step. Using this assay, Bardwell and co-workers2 first found that the missing component is the haem-containing cytochrome bd oxidase complex — a hint that protein folding is linked to the electron-transport chain. Yet disulphide bonds still form normally in a cytochrome bd oxidase-deficient strain of Escherichia coli. So, the authors used membrane fractions of this strain to identify the cytochrome bo oxidase complex as an alternative component that can restore DsbB activity. These results mean that both terminal oxidases of the electron-transport chain in E. coli can independently transfer electrons from DsbB to molecular oxygen via their haem groups. When the authors analysed the membrane fractions from a strain deficient in both terminal oxidases they found that DsbB was not oxidized, showing that no other proteins can catalyse the flow of electrons from DsbB to oxygen.

Do both of these terminal oxidases interact directly with DsbB? Both are known to catalyse the flow of electrons from the ubiquinone pool in the inner membrane to molecular oxygen, suggesting that electrons might flow from DsbB to ubiquinone, then from ubiquinone, via the terminal oxidases, to oxygen6. Indeed, Bardwell and colleagues found that, in vitro, pure DsbB catalyses the oxidation of DsbA by ubiquinone derivatives extremely efficiently. The catalytic power of the purified terminal oxidases is also striking. In a completely reconstituted in vitro redox system, both were catalytically active at concentrations 1,000-fold lower than that of DsbA2.

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Figure 1: Formation of disulphide bonds during protein folding.
Figure 2: Electron-flow pathways for oxidative protein folding under aerobic and anaerobic conditions, as described by Bardwell and colleagues2.

References

  1. Gilbert, H. F. J. Biol. Chem. 272, 29399–29492 (1997).

    Article  CAS  Google Scholar 

  2. Bader, M., Muse, W., Ballou, D. P., Gassner, C. & Bardwell, J. C. A. Cell 98, 217–227 (1999).

    Article  CAS  Google Scholar 

  3. Bardwell, J. C. A., McGovern, K. & Beckwith, J. Cell 67, 581–589 (1991).

    Article  CAS  Google Scholar 

  4. Bardwell J. C. A. et al.Proc. Natl Acad. Sci. USA 90, 1038–1042 (1993).

    Article  ADS  CAS  Google Scholar 

  5. Bader, M., Muse, W., Zander, T. & Bardwell, J. C. A. J. Biol. Chem. 273, 10302–10307 (1998).

    Article  CAS  Google Scholar 

  6. Kobayashi, T. & Ito, K. EMBO J. 18, 1192–1198 (1999).

    Article  CAS  Google Scholar 

  7. Missiakas, D., Georgopoulos, C. & Raina, S. EMBO J. 13, 2013–2020 (1994).

    Article  CAS  Google Scholar 

  8. Bessette, P. H. et al. J. Biol. Chem. 274, 7784–7792 (1999).

    Article  CAS  Google Scholar 

  9. Rietsch, A., Belin, D., Martin, N. & Beckwith, J. Proc. Natl Acad. Sci. USA 93, 13048–13053 (1996).

    Article  ADS  CAS  Google Scholar 

  10. Frand, A. R. & Kaiser, C. A. Mol. Cell 1, 171–182 (1998).

    Article  Google Scholar 

  11. Cuozzo, J. W. & Kaiser, C. A. Nature Cell. Biol. 1, 130–135 (1999).

    Article  CAS  Google Scholar 

  12. Pollard, M. G., Travers, K. J. & Weissman, J. S. Mol. Cell 1, 171–182 (1998).

    Article  CAS  Google Scholar 

Download references

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  1. Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule, Hönggerberg, Zürich, CH-8093, Switzerland

    Rudi Glockshuber

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  1. Rudi Glockshuber
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Correspondence to Rudi Glockshuber.

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Glockshuber, R. Where do the electrons go?. Nature 401, 30–31 (1999). https://doi.org/10.1038/43344

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