FIG 2.

Fis1 and Fis3 are partially required for L. pneumophila intracellular growth in A. castellanii. (A) Intracellular growth assays of fis₁ and fis₂ deletion mutants in A. castellanii. (B) Intracellular growth assays of the fis₃ deletion mutant in A. castellanii. (C) Intracellular growth assays of fis₁, fis₂, and fis₃ deletion mutants in HL-60-derived human macrophages. Symbols: diamond, L. pneumophila wild type (JR32) containing the vector pMMB207; square, icmT deletion mutant containing the vector pMMB207; filled triangle, fis₁ deletion mutant containing the vector pMMB207; open triangle, fis₁ deletion mutant containing the complementing plasmid pZT-207-Ptac-0542; X, fis₂ deletion mutant containing the vector pMMB207; filled circle, fis₃ deletion mutant containing the vector pMMB207; open circle, fis₃ deletion mutant containing the complementing plasmid pZT-207-Ptac-fis3. The experiment was performed as described in Materials and Methods. The experiments were performed three times, and similar results were obtained. (D) The expression levels of fis₁, fis₂, and fis₃ translational lacZ fusions were examined in the wild-type strain (JR32) at the exponential phase (white bars) and at the stationary phase (gray bars). 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.