FIG 3.

Depletion of FtsA inhibits septation and results in cell ballooning and lysis. (A) Growth curves of cells depleted of FtsA in TSB at 37°C using different levels of ZnCl₂ induction to express GFP-FtsA in the Rx1 ΔftsA//P_Zngfp-ftsA⁺ strain. (B) Immunoblots showing native FtsA or GFP-FtsA in uninduced samples (0 mM ZnCl₂) of Rx1 and its merodiploid derivative Rx1 ftsA⁺//P_Zngfp-ftsA⁺ and in uninduced (0 mM ZnCl₂) or induced samples of Rx1 ΔftsA//P_Zngfp-ftsA⁺ (upper image). An anti-FtsZ immunoblot for the same samples was used as a loading control (lower image). (C) Phase-contrast micrographs of representative fields of Rx1 ftsA⁺//P_Zngfp-ftsA⁺ or Rx1 ΔftsA//P_Zngfp-ftsA⁺ cells grown in TSB at 37°C in the absence or in the presence of different ZnCl₂ concentrations (0, 0.075, 0.15, and 0.65 mM), taken 4 h from the start of FtsA depletion (upper images); growth on TSBA plates (Rx1 ftsA⁺//P_Zngfp-ftsA⁺ control strain on the left side and Rx1 ΔftsA//P_Zngfp-ftsA⁺ on the right side) with the same ZnCl₂ concentration is shown in the lower images. O/N, overnight. (D) Combined phase-contrast and fluorescence micrographs of Rx1 ΔftsA//P_Zngfp-ftsA⁺ cells grown in C+Y medium at 37°C with or without different ZnCl₂ concentrations (0, 0.05, 0.10, and 0.15 mM), taken 5 h from the start of FtsA depletion; GFP-FtsA localization to multiple bands in filamentous cells is highlighted by arrows. Average cell length and width at each stage are shown below the corresponding micrograph. Scale bars, 1 μm.