Regulation of the divergent guaBA and xseA promoters of Escherichia coli by the cyclic AMP receptor protein

FEMS Microbiol Lett. 2000 Jun 15;187(2):115-22. doi: 10.1111/j.1574-6968.2000.tb09146.x.


The gua promoter (guaP) of Escherichia coli resembles those for ribosomal RNA (rrn) operons and lies in a close back-to-back arrangement with the promoter for xseA (xseP). Transcription from guaP is subject to stringent control and growth-rate-dependent regulation, and to repression by DnaA and PurR. In addition, transcription from guaP is regulated by the cyclic AMP receptor protein (CRP). Plasmid-borne promoter fusions to the receptor gene for chloramphenicol acetyl transferase were used to assess the role of CRP in controlling transcription from guaP and xseP following a downshift of cultures from rich into minimal medium. CRP is required to activate guaBA transcription and repress xseA transcription following downshift. Bandshift assays with a DNA fragment carrying the divergent promoters revealed specific binding of CRP. We propose that CRP, binding to a near-consensus site centred at -117.5, activates transcription from guaP and obstructs transcription from the xseA promoter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Culture Media
  • Cyclic AMP Receptor Protein / metabolism*
  • Cyclic AMP Receptor Protein / pharmacology
  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Exodeoxyribonucleases / genetics
  • Exodeoxyribonucleases / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Guanine Nucleotides / biosynthesis*
  • Molecular Sequence Data
  • Operon
  • Plasmids
  • Promoter Regions, Genetic / genetics*
  • Transcription, Genetic


  • Culture Media
  • Cyclic AMP Receptor Protein
  • Guanine Nucleotides
  • Exodeoxyribonucleases
  • exodeoxyribonuclease VII