Fig. 1: DivIC is essential for growth, viability and cell size regulation.

a Genetic map of the parental (SH1000) and the divIC conditional lethal (ΔdivIC, SJF5450) strains. b Western blot showing levels of DivIC (15.35 KDa) in SH1000, ΔdivIC in the presence of IPTG or after 1, 2 and 3 h incubation in the absence of IPTG. Anti-DivIC antibodies were used for detection. Levels of YmdA were detected using anti-YmdA as loading control. c Cell growth (top) and viability (bottom) of SH1000, ΔdivIC and ΔdivIB (SJF3883) strains in the presence and absence of IPTG. Graphs show mean and standard deviations of three independent experiments. d Structured Illumination Microscopy (SIM) images of SH1000, ΔdivIC and ΔdivIB cells grown for 2 and 3 h with and without IPTG and treated with NHS-ester 555 to stain cell walls. Images are average intensity projections of z stacks. Scale bars, 2 μm. Data is representative of two independent experiments. e Cell volumes of SH1000, ΔdivIC and ΔdivIB cells grown with and without IPTG for 2 and 3 h (SH1000 and ΔdivIC only), determined from SIM images of cells stained with NHS-ester 555. Each circle indicates a single cell. n = 100 cells for samples taken a 2 h and SH1000 at 3 h, n = 62 and 63 for 3 h plus and minus IPTG respectively. P-values were determined by Mann–Whitney U-tests (****P < 0.0001).