The nucleotide sequence preceding and including the beginning of the ilvE gene of the ilvGEDA operon of Escherichia coli K12.

The DNA sequence of the 570 base pairs that precedes and includes the beginning of the ilvE gene shows no evidence of a leader-attenuator region. Instead, the sequence shows that the ilvE gene is preceded by another structural gene, presumably the normally cryptic ilvG gene. In vitro transcription of the two plasmids (pLC26-3 and pRL5) containing the regulatory region of the ilvEDA operon results in the formation of two "leader" RNAs. These results are consistent with the suggestion that the ilvEDA operon is regulated by an attenuator mechanism and that the attenuator region lies before the ilvG gene.