FIG 9.
Overexpression of the L. micdadei ptsN abolishes the effect of PTSNtr on PmrA-regulated genes in L. pneumophila. The levels of expression of two PmrA-regulated effector-encoding genes (ceg19 and ceg21) were examined in the L. pneumophila wild-type strain (JR32) or the ptsP-ptsO double deletion mutant (SY-ΔptsP-ptsO-Km). The bacteria contained a plasmid with the L. micdadei ptsN gene (Ptac-mic-ptsN) or the mutated L. micdadei ptsNH67A gene (Ptac-mic-ptsNH67A) cloned under the control of the IPTG-inducible Ptac promoter. The plasmids containing the corresponding lacZ fusions of the examined genes without the ptsN gene were used as controls (white bars). The IPTG concentrations used to express the wild-type and mutated L. micdadei ptsN genes were 0, 0.1, and 1 mM. The levels of expression of the lacZ fusions were found to be significantly different (*, P < 10−5, Student's t test) in comparisons between results for the lacZ fusions containing the wild-type L. micdadei ptsN gene expressed from the Ptac promoter and those for the fusions without the ptsN gene. β-Galactosidase activity was measured as described in Materials and Methods. Data (expressed in Miller units [M.U.]) are the averages ± standard deviations (error bars) of the results of at least three different experiments.