Figure 3. The function of the Dot/Icm system is impaired by loss of PC.

(A). Loss of PC results in defective targeting of the Legionella-containing vacuole. Bone marrow-derived macrophages were incubated with noted L. pneumophila strains for 25 min and colocalization of the late endosome/lysosome glycoprotein marker LAMP-1 with bacteria was scored by immunofluorescence microscopy (Experimental Procedures). (B). The absence of PC results in defective translocation of a Dot/Icm substrate. Bacteria were incubated with bone marrow-derived macrophages for one hour and scored for the colocalization of SidC by immunofluorescence microscopy (Experimental Procedures. High DotA: strains contain wild type levels of DotA protein. Low DotA: Strains express attenuated amounts of DotA (Conover et al., 2003). High DotA strains used: pcsA⁺, LP02. Low DotA strains used: pcsA⁺, GL233; pcsA⁻; GL263; pcsA⁻/ppcsA⁺, GL266; dotA⁻, GL83 . ****: P<8.2 × 10⁻⁴. Data shown are the mean ± standard deviation of 3 independent experiments in which 104 phagosomes were quantified for each strain.