Abstract
The regulatory region for the ilvGEDA operon of E. coli K-12 was located and characterized. ilv Leader RNA transcribed from this region is described and the DNA sequence of the region is presented. This DNA sequence contains a transcription promoter, a region coding for a 32-amino-acid polypeptide containing multiple isoleucine, valine and leucine codons and a transcription termination site preceding the 1st structural gene. The mutually exclusive secondary structures of the leader RNA were analyzed. On the basis of these data, a model for the multivalent attenuation of the ilvGEDA operon is proposed.