Control of ilvIH transcription during amino acid downshift in stringent and relaxed strains of Escherichia coli.

ABSTRACT

Transcription of the ilvIH operon was reduced during amino acid starvation of wild-type Escherichia coli. The effect was abolished by a relA mutation and was enhanced by a spoT mutation, thus suggesting a possible negative role of ppGpp accumulation on ilvIH transcription. No effect of amino acid downshift was observed on the synthesis of lrp mRNA, encoding the positive regulator (Lrp) of ilvIH transcription.