FIG 4.

The Legionella CDR system involves a single recombinase. (A) Intermolecular recombination in the wild-type Lp02 strain was compared to that in a 5-deletion strain (lpg0980, lpg0981, lpg1070, lpg1085, and lpg2057 deleted) and a pan-deletion strain with all six recombinase genes deleted (i.e., 5-deletion plus lpg1867 deletion). (B) Intermolecular recombination of the wild-type strain and pan-deletion strain containing the indicated expression plasmids. (C, left panel) Excision of a dif site-flanked kanamycin reporter in the Lp02 pan-deletion strain to assess intramolecular recombination between dif sites. The proportion of kanamycin-resistant cells in the population after transformation with Lpg1867, the catalytic mutant Y387F, or empty vector control was quantified by plating on selective and nonselective media. (Right panel) Excision of a dif site-flanked KanMX reporter in S. cerevisiae BY4741. Bars indicate the mean of three independent experiments, and error bars represent the standard error of the mean (SEM).