Fig. 4. UDP-GlcNAc synthesis associates with mbl mutant lethality.
a Schematic representation of PG precursor synthesis in B. subtilis. b Growth rescue of an mbl mutant by reducing UDP-GlcNAc synthesis. B. subtilis strains YK1538 (Pspac-glmU) and YK2687 (Δmbl Pspac-glmU) were streaked on NA plates containing 0.1 or 1 mM IPTG, with or without 10 μg/ml MC, and incubated for 18 h at 37 °C. c Effects of glmU expression levels on cell morphology of an mbl mutant. Phase contrast micrographs of strains YK1538 (Pspac-glmU) and YK2687 (Δmbl Pspac-glmU) in liquid NB containing 0.1 mM IPTG (upper panels). In the culture of YK2687, IPTG was added to 1 mM, and phase contrast micrographs were captured after 2 and 3 h incubation (bottom panels). Scale bars represent 5 μm. d Cell morphologies shown in panel c were classified into three types (rod, sphere/bulging or phase pale). About 300 cells were examined for each condition. e Effects of glmU expression levels on fosfomycin sensitivity. Disc diffusion assay of B. subtilis strains (wild-type and Pspac-glmU) on NA plates with or without IPTG using paper discs with 6 μl of 1 mg/ml vancomycin or 50 mg/ml fosfomycin. The plates were incubated for 24 h at 37 °C. The figures are representative of at least three independent experiments.