FIGURE 4.

Complementation of ΔzapA with WT ZapA and ZapA variants. E. coli ΔzapA cells were transformed with pBAD24 carrying zapA variants. A, growth was monitored over 6 h, and no significant differences were observed in cell density. B, Western blot analysis using an anti-His antibody confirmed that ZapA variants were expressed to the same levels during the complementation assays in ΔzapA cells (top panel) and Western blot analysis using an anti-FtsZ antibody (bottom panel) was performed as a loading control for comparison. C, cells were visualized by TEM and measured (n > 100 cells per E. coli strain). Mean cell length values ± S.E. were plotted and analyzed by two-tailed t tests as compared with WT cell lengths. NS, no significant difference; ***, p < 0.001. No significant differences in cell length were observed between WT cells and WT ZapA complemented cells and between ΔzapA and pBAD24 vector control cells. D, immunofluorescence was performed to detect differences in FtsZ localization and Z-ring formation among WT cells and ΔzapA cells expressing WT ZapA and ZapA variants. Scale, 1 μm.