A simple mechanism for co-dependence on two activators at an E. coli promoter

Joseph Wade, Tamara Belyaeva, Eva Hyde, Stephen Busby

Research output: Contribution to journalArticle

46 Citations (Scopus)


The Escherichia coli melAB promoter is co-dependent upon two transcription activators, MelR and the cyclic AMP receptor protein, CRP. In this study we demonstrate positive co-operativity between the binding of MelR and CRP at the melAB promoter, which provides a simple mechanism for its co-dependence. MelR binds to four sites, centred at positions -42.5, -62.5, -100.5 and -120.5 relative to the melAB transcription start point. When MelR is pre-bound, CRP is able to bind to a target located between MelR at positions -62.5 and -100.5. This increases the occupation of the two downstream sites for MelR, which is essential for transcription activation. We have identified residues within activating region 1 (AR1) of CRP that are important in transcription activation of the melAB promoter. At simple CRP-dependent promoters, the surface of CRP containing these residues is involved in contacting the RNA polymerase alpha the surface of CRP containing ARI contacts MelR rather than RNA polymerase. Thus, MelR and CRP activate transcription by a novel mechanism in which they bind cooperatively to adjacent sites and form a bacterial enhanceosome.
Original languageEnglish
Pages (from-to)7160-7167
Number of pages8
JournalThe EMBO journal
Issue number24
Publication statusPublished - 17 Dec 2001


  • protein-protein interactions
  • co-dependence
  • CRP
  • Escherichia coli
  • transcription activation


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