A common structural feature in promoter sequences of E. coli.

We have searched promoter regions of E. coli, structural genes of the same organism, and computer-generated random sequence DNA for the occurrence of common structural features. This is done by converting the base sequence to a series of numbers representing the sequence of helix twist angles and examining these numerical sequences statistically. Common structural features are shared by the promoter regions with a much higher frequency than are found in structural genes or in random sequences. These structures appear to be scattered randomly throughout the promoters, both in terms of the number of such structures per promoter and in terms of location within each promoter. One particular structure consisting of five successive helix twist angles is reported, along with a list of 60 different hexanucleotide sequences that share this structure. The locations of these structural elements in 61 E. coli promoters are also tabulated.