Enhancement of bacterial gene expression by insertion elements or by mutation in a CAP-cAMP binding site.
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.
D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D002373:Cyclic AMP Receptor Protein; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004742:Enhancer Elements, Genetic; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D005809:Genes, Regulator; D009154:Mutation; D010957:Plasmids; D014158:Transcription, Genetic
D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D000242:Cyclic AMP