Repression of the araBAD promoter from araO1

J Mol Biol. 1992 Mar 20;224(2):335-41. doi: 10.1016/0022-2836(92)90998-y.


DNA looping between the araO2 and araI sites holds the uninduced or basal level of expression of the araBAD genes from the pBAD promoter at a low level. Despite the presence of another and closer site potentially capable of mediating looping to araI, no repression from this site, called araO1, is observed. Here we show, using both in vivo and in vitro experiments, that the araO1 site is not normally occupied by AraC protein under repressing conditions, but that if AraC protein is overproduced and the araO2 site is absent, araO1 is then occupied and repression of pBAD can be observed.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • AraC Transcription Factor
  • Arabinose / genetics*
  • Arabinose / metabolism
  • Bacterial Proteins*
  • Base Sequence
  • DNA, Bacterial / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli Proteins
  • Gene Expression Regulation, Bacterial*
  • Molecular Sequence Data
  • Mutagens
  • Promoter Regions, Genetic*
  • Repressor Proteins / metabolism*
  • Sulfuric Acid Esters
  • Transcription Factors*


  • AraC Transcription Factor
  • AraC protein, E coli
  • Bacterial Proteins
  • DNA, Bacterial
  • Escherichia coli Proteins
  • Mutagens
  • Repressor Proteins
  • Sulfuric Acid Esters
  • Transcription Factors
  • Arabinose
  • dimethyl sulfate