Open AccessA stereospecific alignment between the promoter and the cis ‐acting sequence is required for Lrp‐dependent activation of ilvIH transcription in Escherichia coli
Author(s) -
Sacco Margherita,
Ricca Ezio,
Marasco Rosangela,
Paradiso Roberta,
De Felice Maurilio
Publication year - 1993
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1993.tb06053.x
Subject(s) - operon , transcription (linguistics) , promoter , leucine , gene , biology , microbiology and biotechnology , dna , lac operon , chemistry , genetics , escherichia coli , gene expression , amino acid , linguistics , philosophy
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.