Structure and regulation of the dnaA promoter region in three Streptomycesspecies

The regulatory region of the Streptomyces dnaA gene comprises a single prom oter and two DnaA boxes that are located upstream of the promoter. Comparat ive analysis of the dnaA promoter region from S. chrysomallus, S. lividans and S. reticuli revealed that the location, spacing and orientation of the DnaA boxes are conserved. In vitro studies demonstrated that efficient bind ing of the Streptomyces DnaA protein to DNA requires the presence of two Dn aA boxes. In vivo analysis of dnaA promoter mutants deleted for one or both DnaA boxes indicated that the dnaA gene is autoregulated. However, the deg ree of derepression observed is relatively modest.