FIG 2.
Cytotoxicity of EssD in E. coli. (A) Diagram depicting plasmid constructs with ara and lac promoters. (B to D) Growth and viability of E. coli variants harboring plasmids carrying the essD and essI genes. Overnight cultures were normalized to an A600 of 5, diluted 1:100 into fresh medium with (+) or without (−) arabinose (ara) and grown at 37°C. IPTG was added 3 h after dilution. Growth was monitored as increased absorbance (A600) over 6 h (B). At timed intervals (0, 1, and 2 h) after IPTG addition (T0, T1, and T2), cultures of the Plac-essD Para-essI6-10 strain grown with or without arabinose and with IPTG were examined for integrity of genetic content (C) and for viability (D). Cells were stained with DAPI and visualized with an Olympus AX70 microscope and UV filter. Pseudocolor was used for image display in panel C. Cultures were serially diluted (0 to −5), and 10-μl aliquots of each dilution were spotted on agar medium containing ampicillin, kanamycin, and arabinose. An image of the plate after overnight incubation at 30°C is shown in panel D.