Fig. 4.

Regulatory functions of SsrB C203S. (A) SPI2 expression was induced in wild-type and ssrB C203S-expressing Salmonella by shifting the bacteria grown to an OD₆₀₀ of 0.5 in 10 mM MgCl₂ N9 medium into 8 μM MgCl₂ N9 medium. Expression of SPI2 genes quantified as β-galactosidase of the lacZY transcriptional fusions is expressed in Miller Units (M.U.) 3 h after the shift. The data represent eight observations from three independent experiments. (B) Transcriptional sifA::lacZY activity also was measured in gp91phox (phox) and gp91phox iNOS-deficient (phox iNOS) macrophages as described in SI Materials and Methods. Data are represented as arbitrary units of light/10⁶ bacteria (A.U.) ± SEM from four independent observations.