Isolation and characterization of a priB mutant of Escherichia coli influencing plasmid copy number of delta rop ColE1-type plasmids.

The lethality induced by the overproduction in Escherichia coli of a heterologous protein was used to select bacterial mutants. In one of these, the mutation responsible was mapped to priB. We describe the isolation of this mutant, the sequencing of the mutated gene, and its in vivo effect on plasmid replication.