FIG. 3.

Effect of overproduction of inactive derivatives of E. coli (Ec) (top) or P. aeruginosa (Pa) (bottom) PBP 2 on cellular morphology of E. coli BL21. Cells harboring the respective plasmids for the overproduction of (A) the catalytic Ser→Ala mutant PBPs or (B) the isolated n-PB modules were induced with 1 mM IPTG and grown in LB at 37°C for the times indicated. (a, e, c, and g) Western immunoblot analysis of PBP 2 production during the 5-h incubation of induced cells. (b, d, f, and h) Phase-contrast micrographs of representative cells sampled at 0 and 3 h post-IPTG induction.