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DNA supercoiling depends on the phosphorylation potential in Escherichia coli

Authors

  • Marielle van Workum,

    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
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  • Silvy J. M. van Dooren,

    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
    2. Department of Microbial Physiology, Free University, de Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands.
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  • Nienke Oldenburg,

    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
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  • Douwe Molenaar,

    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
    2. Department of Microbial Physiology, Free University, de Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands.
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  • Peter R. Jensen,

    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
    2. Department of Microbiology, Technical University of Denmark, Building 221, DK-2800 Lyngby, Denmark.
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  • Jacky L. Snoep,

    Corresponding author
    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
    2. Department of Microbial Physiology, Free University, de Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands.
    • *For correspondence (address no. 2). E-mail hw@bio.vu.nl; Tel. (20) 4447230; Fax (20) 4447229.

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  • Hans V. Westerhoff'

    Corresponding author
    1. Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, NL-1066 CX Amsterdam, The Netherlands.
    2. Department of Microbial Physiology, Free University, de Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands.
    3. E. C. Slater Institute, BioCentrum, University of Amsterdam, Amsterdam, The Netherlands.
    • *For correspondence (address no. 2). E-mail hw@bio.vu.nl; Tel. (20) 4447230; Fax (20) 4447229.

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Summary

ATP/ADP ratios were varied in different ways and the degree of negative supercoiling was determined in Escherichia coli. Independent of whether the ATP/ADP ratio was reduced by a shift to anaerobic conditions, by addition of a protonophore (dinitrophenol) or by potassium cyanide addition, DNA supercoiling decreased similarly with the ATP/ADP ratio. The experiments were performed under well-defined conditions, where oxidative phosphorylation was the dominant route for ATP synthesis, i.e. using a minimal salts medium with succinate as the sole free-energy and carbon source, and in the presence or absence of ammonia as the nitrogen source. The results of the different experiments were consistent with a single linear relationship between the log(ATP/ADP) and the change in linking number. The dependence of DNA supercoiling on the ATP/ADP ratio was not influenced by inhibitors of transcription or translation. Because the ATP/ADP ratio was modulated in different ways, the unique relationship suggests coupling between the phosphorylation potential and DNA supercoiling. This was most probably mediated by the DNA gyrase, independent of topoisomerase I or transcription.

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