Systematic characterization of curved DNA segments randomly cloned from Escherichia coli and their functional significance.

In addition to the set of curved DNA segments isolated previously from Escherichia coli, another set of curved DNA segments has now been isolated. To gain an insight into the functional significance of these curved DNA sequences, systematic analyses were carried out, which included not only mapping of the precise locations of the segments on the E. coli chromosome but also clarification of the gene organization in the chromosomal regions surrounding the curved DNA sequences. It was demonstrated that most of the curved DNA sequences, which have been characterized so far, appear to be located immediately upstream of the coding sequences of adjacent genes. It was also demonstrated that an E. coli histone-like protein, named H-NS (or H1a), exhibits a strong affinity for naturally occurring curved DNA sequences in regions upstream promoters.