Wag31 localization is altered in the absence of MtrB. (A) Pami::wag31-mCherry expressing M. smegmatis WT (i and ii), the ΔmtrB strain (iii and iv), and M. smegmatis overproducing MtrB (v and vi) or MtrBH305Y (vii and viii) were grown with 0.2% acetamide for 3 h and visualized as described in the legend to Fig. 3A. Top panels are bright-field images; bottom panels are fluorescence images. Arrow, septal localization; arrowhead, polar localization. Percent septal Wag31-mCherry localizations from two independent experiments were scored, and averages ± standard errors are given in the respective fluorescent panels. Each experiment included >132 cells from each strain. Black arrows, septa in multiseptate ΔmtrB strain; white arrows and arrowheads, septal and polar localizations, respectively. (B) FtsZ-GFP localization in WT (i and ii) and the ΔmtrB strain (iii and iv). Arrow, FtsZ-GFP rings.