Activation by NarL at the Escherichia coli ogt promoter

Patcharawarin Ruanto, David J Chismon, Joanne Hothersall, Rita E Godfrey, David J Lee, Stephen J W Busby, Douglas F Browning

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The Escherichia coli NarX/NarL two-component response regulator system regulates gene expression in response to nitrate ions and the NarL protein is a global transcription factor, which activates transcript initiation at many target promoters. One such target, the E. coliogt promoter, which controls the expression of an O6‑alkylguanine-DNA-alkyltransferase, is dependent on NarL binding to two DNA targets centred at positions -44.5 and -77.5 upstream from the transcript start. Here, we describe ogt promoter derivatives that can be activated solely by NarL binding either at position -44.5 or position -77.5. We show that NarL can also activate the ogt promoter when located at position -67.5. We present data to argue that NarL-dependent activation of transcript initiation at the ogt promoter results from a direct interaction between NarL and a determinant in the C-terminal domain of the RNA polymerase α subunit. Footprinting experiments show that, at the -44.5 promoter, NarL and the C-terminal domain of the RNA polymerase α subunit bind to opposite faces of promoter DNA, suggesting an unusual mechanism of transcription activation. Our work suggests new organisations for activator-dependent transcription at promoters and future applications for biotechnology.

Original languageEnglish
Pages (from-to)2807-2820
Number of pages14
JournalThe Biochemical journal
Issue number15
Early online date7 Aug 2020
Publication statusPublished - 14 Aug 2020

Bibliographical note

© 2020 The Author(s).


  • molecular interactions
  • NarL, promoters
  • transcription activation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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