Fig. 2
PrtR1 directly inhibits the expression of the R-tailocin gene cluster in CHA0 by interacting with the upstream region of the cluster. (A) The expression of the R-tailocin gene cluster and the locus-specific regulatory gene prtR1 was monitored using transcriptional reporters pOT1e-Phol-egfp and pOT1e-PprtR1-egfp, respectively, in the wild type CHA0 (black) and its mutants ΔprtR1* (pink) and Δtailcluster (burgundy). Strains were grown in rich medium (NYB) following induction with 9 µM mitomycin C or without induction. Optical density at 600 nm and GFP fluorescence (relative fluorescence units, RFU) were monitored every 10 min for 24 h in a BioTeK Synergy H1 plate reader. Detailed curves are shown in Supplementary Fig. S2. The data were then used to calculate the area under the RFU curve. Statistical differences were assessed by Kruskal-Wallis tests with Bonferroni correction and are indicated by letters. A minimum of three biological replicates with at least three technical replicates are plotted. (B) ChIP-seq results over the R-tailocin gene cluster of CHA0 for PrtR1 under non-induced (NI, blue) and induced (I, 9 µM mitomycin C, green) conditions. The genes encoding the structural parts of the R-tailocin #1 and the R-tailocin #2 are colored red and green, respectively, the prtR1 gene is colored pink, the gene encoding the lytic holin (hol) is colored yellow, other genes belonging to the cluster are colored white, and the bacterial genes neighboring the R-tailocin gene cluster are colored black