DNA sequence of the promoter region for the alpha ribosomal protein operon in Escherichia coli

Abstract

Previous studies showed that the gene for RNA polymerase subunit alpha at 72 min on the Escherichia coli chromosome is co-transcribed with genes for ribosomal proteins (r-proteins) S11, S4, and L17, and probably S13. DNA sequence analysis of a deletion mutant has now established that the S13 gene is a part of the alpha operon and the gene order is promoter (P alpha), rpsM (S13), rpsK (S11), rpsD(S4), rpoA(alpha), and rplQ(L17). The DNA sequence extending 650 bases before S13 gene was determined. In vitro transcription experiments establish the probable location of the alpha promoter (P alpha) within this sequence. The start site is 94 nucleotides upstream from the initiation codon (GUG) of the S13 gene. This promoter has features previously noted as common to E. coli promoters. However, comparison with four other sequenced promoters of r-protein operons shows no unique common features that might account for the common regulation of synthesis of r-proteins. This lack of sequence similarity in promoters of r-protein operons may be because r-protein synthesis is regulated at least partially at a post-transcriptional level.