Enhancement of bacterial gene expression by insertion elements or by mutation in a CAP-cAMP binding site

J Mol Biol. 1986 Sep 5;191(1):85-95. doi: 10.1016/0022-2836(86)90424-9.


The regulatory region (bglR) of the cryptic bgl operon was characterized by DNA sequence analysis and transcription mapping. Bgl(-)-specific transcription was found to occur in both the wild-type Bgl- and mutant Bgl+ cells. However, the steady-state level of bgl RNA was much higher in the Bgl+ mutant than in the wild-type. Activation of the bgl operon by insertion sequence-mediated bglR mutations or point mutations in bglR is therefore the result of increased transcription. The ethylmethane sulfonate-induced point mutations in bglR are alterations in a single base in the cAMP binding protein (CAP) binding site, leading to a stronger binding of the CAP-cAMP complex. The IS1 and IS5-mediated bglR mutations analyzed show that the insertion sequences can activate the bgl operon by integration 78 to 125 base-pairs upstream from the transcription initiation site. The role of the insertion sequences in activation of the bgl operon is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cyclic AMP / metabolism
  • Cyclic AMP Receptor Protein*
  • DNA Transposable Elements*
  • DNA, Bacterial
  • Enhancer Elements, Genetic*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression Regulation*
  • Genes, Regulator*
  • Mutation*
  • Plasmids
  • Transcription, Genetic


  • Carrier Proteins
  • Cyclic AMP Receptor Protein
  • DNA Transposable Elements
  • DNA, Bacterial
  • Cyclic AMP

Associated data

  • GENBANK/X04340