Figure 2

Mutation in the predicted porter domain of MexB affected the selective efflux of aycl-HSLs by MexAB-OprM. P. aeruginosa strains were grown in LB medium with acyl-HSLs, and lasB expression analyses were performed as described in Materials and Methods. Promoter activities are expressed in fluorescence intensities (arbitrary units) depending on amounts of green-fluorescence protein (GFP) derived from PlasB-gfp at emission (490 nm; excitation, 510 nm). The following MexB mutant strains were used: KG7403, KG7503, KG7503 carrying pKTA113 (wild-type MexB), pYT57 (MexB Phe136Ala), and pYT81 (MexB Asp681Ala). The data represent mean values of three independent experiments. Error bars represent the standard errors of the means.