Increased expression of the dnaA gene has no effect on DNA replication in a dnaA+ strain of Escherichia coli.
We have constructed a pBR322 plasmid derivative which expresses dnaA protein under the control of the E. coli lac UV5 promotor. Expression of the dnaA protein from the plasmid is inducible by isopropyl-beta-D-thiogalactoside. In a dnaA+ strain induction has no effect on the accumulation of DNA. In contrast, in a thermosensitive dnaA46 strain, induction, at either the permissive or the nonpermissive temperature, results in an immediate stimulation of DNA accumulation. We conclude that, while in a dnaA46 strain dnaA protein limits DNA replication, in a dnaA+ strain dnaA protein activity does not control the timing of replication initiation.
D001426:Bacterial Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004261:DNA Replication; D004926:Escherichia coli / Q000235:genetics*
D001426:Bacterial Proteins