High incidence of transposon Tn3 insertions into a replication control gene of the chimeric R/Ent plasmid pCG86 of Escherichia coli.

Insertion of transposon Tn3 into the chimeric R/Ent plasmid pCG86 occurred preferentially into a replication control gene, generating mutants with increased plasmid copy number. In two mutants, the nucleotide sequence of the region of the gene containing the Tn3 insertion was determined.