FIG. 4.

PB susceptibility (PB MIC) of gonococcal strains expressing lptA. PB susceptibility was determined by the method of Tzeng et al. (49) using wt strain FA19, its lptA::spc mutant (labeled lptA), the lptA⁺ complemented derivative (labeled lptA Comp), and the complemented control (labeled Comp Control), which lacks the ectopically expressed lptA gene but contains the NICS sequence from pGCC4 (see Materials and Methods). The assay was performed in the presence or absence of 1 mM IPTG, and the results are representative of two independent experiments.