Detection of an extended –10 element in the promoter region of the pckA gene encoding phosphoenolpyruvate carboxykinase in Escherichia coli

Abstract

The regulation of transcription of the pckA gene coding for phosphoenolpyruvate carboxykinase in Escherichia coli was analysed by site-directed mutagenesis of the promoter region and measurement of in vitro transcription initiation. Mutation of the guanine residue at position –14 to either cytosine or thymine was found to result in a drastic decrease of transcription, even in the presence of the natural –35 hexamer TTTCCA that differs by only two nucleotides from the consensus sequence TTGACA. It was concluded that the promoter region of pckA contains an extended –10 module, 5`-TG-3`, located one base upstream of the –10 hexamer, which is crucial for transcription.