Figure 4

AmrZ is a transcriptional repressor of genes implicated in iron homeostasis. 10 genes potentially implicated in iron homeostasis and that appeared as enriched in the ChIP-seq analysis were selected for expression analysis (qPCR). A. Relative expression of the genes in P. fluorescens F113 after growth in iron sufficient medium (SA supplemented with 100 μM FeCl₃, black bars) or iron limited medium (SA, gray bars). RNA was extracted from cells grown to 1.2 O.D.₆₀₀. Asterisks denotes statistically significant differences, p < 0.05. All genes appear to be induced under iron deficiency. B. Relative expression of the same genes in P. fluorescens F113 (black bars) and an amrZ mutant (gray bars). Numbers correspond to PSF113 annotation. RNA was extracted from cells grown under iron limiting conditions (SA medium) at 1.2 O.D.₆₀₀. Statistically significant differences are denoted by one (p < 0.1) or two asterisks (p < 0.05). All tested genes appear to be transcriptionally repressed by AmrZ.