Nucleotide sequence of the promoter-operator region of the tryptophan operon of Salmonella typhimurium

Abstract

The promoter-operator region of the tryptophan operon of Salmonella typhimurium was identified by the presence of an HpaI restriction site which is protected from HpaI endonuclease cleavage by Escherichia coli RNA polymerase or tryptophan repressor. The DNA sequence on either side of this HpaI site was determined by DNA sequencing. Of the 105 nucleotide pairs reported here, 81 are conserved in the corresponding region of the trp operon of E. coli. The highly symmetrical operator region around the HpaI site exhibits almost complete homology with that in E. coli. The relation of conserved and non-conserved regions of the DNA sequence to the structure of the RNA polymerase initiation complex is discussed.