The dnaA gene product is not required during stable chromosome replication in Escherichia coli.

Exposure of Escherichia coli dnaA strains to UV light results in a transient resumption of chromosome replication at 42 degrees C, the temperature restrictive to these mutants. Capability of dnaA mutants to replicate DNA at 42 degrees C can be stabilized, however, when either protein or RNA synthesis is inhibited 60 min after UV irradiation. DNA synthesis proceeds for several hours under these conditions. These results indicate that dnaA dependent transcription is not involved in initiation of chromosome cycles during stable DNA synthesis.