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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Abstract

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
Volume866
Issue number1
DOIs
Publication statusPublished - Feb 24 1986

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Keywords

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

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Genetics

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