(A) ECA biosynthesis pathway. Abbreviations: P-Gc, Glucose 1-phosphate; UDP, uridine diphosphate; G, N-acetylglucosamine; dTDP, thymidine diphosphate; Ma, N-acetyl-D-mannosaminuronic acid; Gt, 4-acetamido-4,6-dideoxy-D-galactose. In E. coli, loss of RffH is compensated for by RmlA. RmlA is involved in the synthesis of dTDP-L-rhamnose, an O-antigen precursor (Stevenson et al., 1994). The figure was adapted from Paradis-Bleau et al. (Paradis-Bleau et al., 2014). (B) Phenotypes of ΔwecE mutant cells. Cells were grown at 37°C in LB to an OD600=0.5–0.6, then fixed and photographed by phase-contrast microscopy. The white bar represents 4 μm. (C) Flow cytometry. Histograms of the FSC-A of live cells shown in panel B. The dashed line represents the mean forward scatter area of the WT. Mean of the forward scatter area is reported in arbitrary units (AU). Flow cytometry data is from 100,000 events (cells). Data is representative of two independent experiments. Strains: MAJ3 (WT), MAJ73 (ΔwecE), MAJ89 (ΔwecA), and MAJ90 (ΔwecEA).