Temperature-Sensitive Initiation of Chromosome Replication in a Mutant of Escherichia coli

The properties of Escherichia coli mutant D2-47LT indicate that it is temperature-sensitive for a protein required for the initiation of chromosome replication. The results of several different experiments are consistent with this hypothesis, and no support was found for the alternate hypotheses tested. Although the strain is usually unable to initiate replication at 42 C, some of the initiation proteins are apparently synthesized at the restrictive temperature. This can cause initiation on partially replicated, but not completed, chromosomes. It appears that the temperature-sensitive protein is required for initiation on completed chromosomes.