FIG 4.

CsrA and LetA affect the levels of expression of different effector lacZ fusions similarly. (A) The levels of expression of the lpg2461, mavT, and mavQ lacZ fusions were examined in L. pneumophila wild-type strain JR32 (diagonal striped bars) and L. pneumophila rsmY deletion mutant MR-rsmY (boxed bars). The bacteria examined contained a plasmid with the csrA gene cloned under the control of the Ptac promoter (activated by IPTG). (B) The same effector lacZ fusions were examined in the L. pneumophila letA deletion mutant OG2001 (waved bars) and the L. pneumophila rsmYZ double-deletion mutant MR-rsmYZ (gray bars). The bacteria examined contained a plasmid with the letA gene cloned under the control of the Ptac promoter. In the experiments represented in both panel A and panel B, the strains were grown in media containing different concentrations of IPTG (indicated below the bars) and β-galactosidase activity was measured at the stationary phase as described in Materials and Methods. The data are the averages ± standard deviations (error bars) of the results of at least three different experiments. (C) Comparison of the effects of different mutants and overexpression conditions on the level of expression of the effector lacZ fusions examined as described for panels A and B. The mutants and overexpression conditions compared are indicated below the bars. (D) Data represent the results of experiments performed as described for panel C, but the degree of the effect on lpg2461 was normalized to 100% and the relative effects on mavT and mavQ genes were calculated in relation to it. ver, versus.