Involvement of Escherichia coli K‐12 recombination functions in elimination of multicopy plasmid R6K by DNA‐damaging agents

Drugs that damage DNA by different mechanisms eliminate an F‐lac+ plasmid and multicopy plasmid R6K from Escherichia coli K‐12 wild type (polA+rec+). However, low‐copy plasmid R1 is refractory to elimination under identical conditions. R6K is not eliminated from a polA mutant, which suggests that curing is not due to reduced availability of DNA polymerase I for plasmid replication in cells undergoing DNA repair. R6K is eliminated almost three times faster from a recBrecC sbcB mutant than from wild‐type strains, whereas elimination from a recF mutant occurs at a rate similar to wild type. Hence, recombination may be involved in drug‐mediated elimination of R6K, particularly in cells that carry out recF‐dependent recombination exclusively.