FIG 4.

Numerous L. pneumophila effector-encoding genes are repressed by the Fis1 and Fis3 regulators. The expression levels of effector translational lacZ fusions (the effectors examined are indicated below the bars) were examined at exponential phase in the wild-type strain (JR32) (white bars), in the fis₁ deletion mutant (ZT-Fis1) (bars with diagonal stripes), in the fis₂ deletion mutant (ZT-Fis2) (dotted bars), and in the fis₃ deletion mutant (ZT-Fis3) (bars with wavy stripes). (A) effector-encoding genes affected strongly by the fis₃ deletion mutant and weakly by the fis₁ deletion mutant. (B) Effector-encoding genes affected strongly by the fis₁ deletion mutant and weakly by the fis₃ deletion mutant. (C) Effector-encoding genes affected similarly by the fis₁ and fis₃ deletion mutants. 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. In each panel the effector-encoding genes were divided according to their levels of expression.