Fig 1.

Regulation of mar-sox-rob gene expression by MarA, SoxS, and Rob. (A) Strains contain plasmids pBAD30, pMarA, pSoxS, and pRob and single-copy, yfp transcriptional fusions. marRAB, soxS, and rob were deleted from cells, and cells contained a constitutively active mutant of SoxR (soxR105). Cells were grown in LB–0.2% arabinose medium for 4 h prior to fluorescence and optical density measurements. Fluorescence values have been divided by the optical density and then normalized to the value for the empty-plasmid (pBAD30) negative control. (B) mar-sox-rob regulatory network inferred from the data in panel A. Dark lines, interactions found to be significant under physiological conditions; gray lines, interactions found to be significant only when regulators are overexpressed. Strains used were CR917 (marRAB promoter), CR918 (soxS promoter), CR219 (rob promoter), and CR920 (inaA promoter) harboring pBAD30, pMarA, pSoxS, and pRob, respectively.