FIG 2.

PdeL regulates the fliF and sslE promoters. Expression levels of P_fliF mNeonGreen and P_sslE lacZ fusions were determined by flow cytometry (fluorescence-activated cell sorter [FACS]) and β-galactosidase activity assays, respectively. (A) The activity of P_fliF mNeonGreen was tested in the absence (control) and presence of PdeL (+PdeL) of double transformants of ΔpdeL strain T2057. The P_fliF mNeonGreen reporter was provided by low-copy-number plasmid pKECY28 (P_fliF mNG); a constitutive P_lacUV5 mNeonGreen reporter (P_UV5 mNG) (provided by pKESL279) and a promoterless mNeonGreen (mNG) promoter (pKECY26) served as controls. Plasmid pKESL162 carries pdeL under the control of P_tac, and parent vector plasmid pKESK22 was used as a control. Cultures were grown in tryptone medium with antibiotics but without the addition of IPTG. Shown are histograms depicting the fluorescence of samples taken after 3 h of growth (OD₆₀₀ ranging from 0.8 to 1). For each sample, 200,000 bacteria were counted. (B) Mean fluorescence intensities (in arbitrary units) from two independent experiments after 3 h of growth. (C) The activity of the P_sslE lacZ fusion was determined in double transformants of ΔpdeL mutant strain U266. The P_sslE lacZ reporter was provided by low-copy-number plasmid pKECY46. PdeL was provided under the control of P_tac by pKESL162. Vector plasmid pKESK22 was used as a control in ΔpdeL strain U266 and parental strain U4 (wild type [wt]). Cultures for β-galactosidase assays were grown as described above for panel A. Mean values from at least 3 replicates are shown as bars, and error bars indicate standard deviations.