FIG. 1.
rep uvrD lethality is suppressed by recQ or recJ inactivation. Segregation experiments were carried out as described in Materials and Methods. Briefly, plasmid-containing cells grown at 30°C were shifted to 42°C at time zero. After 2 to 4 h, they plateau due to the lack of plasmid replication at high temperature (open symbols), while plasmidless cells appear (closed symbols). No plasmidless cells appeared with the rep uvrD double mutant, while they did appear with similar kinetics with rep uvrD recR, recJ, or recQ triple mutants (and with the rep single mutant, JJC760; data not shown). Open symbols are CFU on spectinomycin plates, i.e., pGBts-rep-containing strains. Closed symbols are pGBts-rep-cured strains, measured as CFU on MM, identified as Spts. Circles, JJC1708 [rep uvrD (pGBts-rep)]; triangles, JJC2417 [rep uvrD recR (pGBts-rep)]; squares, JJC3121 [rep uvrD recJ (pGBts-rep)]; diamonds, JJC3122 [rep uvrD recQ (pGBts-rep)].