The role of upstream sequences in determining the strength of an rRNA promoter of E. coli

Árpád Pethő, Jörn Belter, Imre Boros, Pál Venetianer

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In vitro transcription experiments were carried out with recombinant plasmids containing the promoters of the rrnB gene of Escherichia coli, and with deletion mutants lacking various lengths of the AT-rich sequence upstream from the P 1 promoter of that gene. The main conclusions are as follows: (a) The in vitro transcriptional activity of the P 1 and P 2 promoters of the rrnB gene are an order of magnitude higher on closed-circular (supercoiled) templates than on linear DNA; (2) the strong P 1 and P 2 promoters are heparin-sensitive on linear templates, and on circular DNA only P 2 is heparin-resistant; (3) removal of the upstream AT-rich region did not decrease the apparent in vitro strength of the P 1 promoter under standard conditions (50 mM KCl, high RNA polymerase DNA ratio); (4) at higher salt concentrations, or with a lower RNA polymerase DNA ratio, the deletion mutants displayed much lower in vitro transcriptional activity than the wild-type, and the apparent weakening of the P 1 promoter was roughly proportional to the length of the deleted AT-rich sequence. The implications of these findings for the possible in vivo role of the AT-rich region are discussed.

Original languageEnglish
Pages (from-to)37-43
Number of pages7
JournalBBA - Gene Structure and Expression
Issue number1
Publication statusPublished - Feb 24 1986



  • (E. coli)
  • Transcriptional activity
  • Upstream region
  • rRNA promoter

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Genetics

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