Nucleotide sequence of the attenuator region of the histidine operon of Escherichia coli K-12.

The attenuator region of the histidine operon of Escherichia coli K-12 has a potential coding capacity for two peptides, one of 16 amino acids and another of 30 amino acids. This region is followed by a perfect palindrome of 14 base pairs separated by five nucleotides. A G+C-rich region precedes and follows a possible transcription termination sequence. These features are compatible with a model in which active translation of a leader mRNA interferes with transcription termination, thus causing derepression of the histidine operon. The sequence of the region coding for the hypothetical 16-amino acid peptide is of particular relevance because it indicates the site and a possible mechanism of action of histidyl-tRNAhis in regulating histidine gene expression. Seven contiguous histidine codons are present within this sequence: : formula: (see text)