Fig 1.

Deleting topA complements the growth and Par⁻ phenotype of the gyrB(Ts) strain. (a) Cells of strains RFM445 [gyrB(Ts)] and RFM475 [topA gyrB(Ts)] were grown at 37°C to an OD₆₀₀ of 0.7 and streaked on LB plates. The plates were incubated at 42°C for 24 h. (b, c, and d) Flow cytometry analysis of RFM443, RFM445, and RFM475 cells grown in LB medium. Cell mass (left panels) and DNA content (right panels) parameters are shown. M1 and M2 correspond to anucleate cells (the percentages are indicated in each panel) and to cells with DNA, respectively. (e) DNA/mass ratios were obtained from the data shown in panels b to d (37°C, 40°C, and 42°C, respectively) except for strains RFM445 and RFM475 grown at 42°C, where the data of two additional experiments were used to obtain an average DNA/mass ratio.