High-affinity binding sites for the initiator protein DnaA on the chromosome of Escherichia coli.

The initiator protein DnaA of Escherichia coli binds with unusually high affinity to five regions on the chromosome, in addition to the replication origin, oriC. Using a solid-phase DNA binding assay, in which the DNA binding C-terminal domain of DnaA is bound via a biotin tag to magnetic beads, we could fish only fragments with these six regions from different chromosomal digests. Except for oriC, these fragments contain only one or two consensus DnaA binding sites, DnaA boxes. The distribution of these high-affinity DnaA boxes on the chromosome is random.