Determination of the nucleotide sequence of part of the regulatory region for the galactose operon from Escherichia coli

Abstract

We have determined the sequence of 59 base pairs in the DNA preceding the site for initiation of transcription in the galactose operon. DNA from a lambdagal transducing phage was digested with restriction endonucleases to obtain a DNA fragment from the gal regulatory region. This fragment extends from 59 base pairs prior to the transcription initiation site through the 45 base pairs which specify the 5'-terminal sequence of gal mRNA. Analyses of RNA transcripts derived from this fragment and a variety of direct DNA sequence analyses allowed us to deduce the following sequence for the DNA in this fragment: (formula: see text) Position +1 corresponds to the site for initiation of gal mRNA synthesized in the presence of cyclic AMP and its receptor protein, CRP. Transcription experiments indicate, however, that this fragment lacks some element of the gal promoter required for the stimulation of transcription by CRP-cAMP. There are, nonetheless, some similarities between the gal sequence preceding the transcription start site and the sequences of other promoter regions. These include the heptamer sequence T-A-T-G-G-T-T (--12 to --8) and the sequence A-C-A-C-T-T-T (--36 to --30).