A stereospecific alignment between the promoter and the cis-acting sequence is required for Lrp-dependent activation of ilvIH transcription in Escherichia coli.
The leucine-responsive regulatory protein (Lrp) is a DNA binding protein that affects, either positively or negatively, the expression of several E. coli genes. The ilvIH operon is positively regulated by Lrp and leucine counteracts this effect reducing 5- to 10-fold the efficiency of ilvIH transcription. An investigation of the mechanism of transcription activation of the ilvIH operon by Lrp indicated that: (i) a stereospecific alignment between the ilvIH promoter and the cis-acting sequence upstream of it is required for activation; (ii) a correct distance between the promoter and the adjacent cis-acting sequence is needed for leucine to counteract the positive role of Lrp; (iii) Lrp fails to activate transcription when the cis-acting region is placed several hundred base pairs upstream of the ilvIH promoter.
Sacco
M
M
International Institute of Genetics and Biophysics, CNR, Naples, Italy.
Ricca
E
E
Marasco
R
R
Paradiso
R
R
De Felice
M
M
D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D051756:Leucine-Responsive Regulatory Protein; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014157:Transcription Factors; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C497278:Lrp protein, E coli; D014157:Transcription Factors; D051756:Leucine-Responsive Regulatory Protein