Figure 7. Promoter recognition and transcription activity.

(a) The bindings between PmrA, WT-PmrA or its variants and DNA measured by fluorescence polarization experiments are fitted by a one-site binding model. See also Supplementary Fig. 11 for binding affinities. (b) β-Galactosidase reporter assay in K. pneumoniae carrying the plasmid that expresses PmrA, WT-PmrA or its variants and the reporter plasmid that contains the pbgP promoter in front of the lacZ gene. The expression of PmrA, WT-PmrA or its variants was induced by isopropyl-β-D-thiogalactoside (IPTG, 1 mM ml⁻¹) until the cells grew to the mid-logarithmic phase. The β-galactosidase assay in cells that carry WT-PmrA plasmid but without the addition of IPTG is denoted non-WT, which represents the production of β-galactosidase induced by endogenous PmrA. Reporter assay results are expressed as Miller Units. All experiments were performed in triplicate. Error bars are defined as s.d.