Fig. 2

Increasing Und-P levels promotes enterobacterial common antigen surface expression in E. coli. (A) Dot blot showing that increasing Und-P levels by overexpressing uppS promotes surface expression of ECA in E. coli. Cells were grown at 37 °C in LB media containing 500 µM IPTG (0 µM IPTG for baseline [BL]). Cells lacking WecA do not produce ECA (negative control). (B) Densitometry was performed from dot blots to quantitate surface expression of ECA. Signal values are given as a percent of the average wbbL::IS5/vector (wbbL::IS5 is E. coli MG1655) signal. All data are representative of three independent experiments. Error bars show +/- standard error of the means. Significance was determined by using an ordinary one-way ANOVA test with Dunnett’s multiple correction. Asterisks above sample bars denote significance relative to wbbL::IS5/vector. *p < 0.05, **** <0.0001. (C) Western blotting was used to examine the effect of increasing Und-P levels on ECA chain length from cells grown in panel A. *, nonspecific band. MreB, which has a predicted molecular mass of 37 kDa, served as the loading control. The E. coli strains shown are MAJ286 (wbbL::IS5/vector), MAJ981 (ΔwecA/vector), MAJ1354 (wbbL::IS5/puppS), and MAJ1677 (ΔwecA/puppS).