The reduction in <i>ppnKB</i> mRNA levels upon induction of RoxS expression is reversible and depends primarily on RNase Y.

<p>(A) Northern of total RNA isolated from strain CCB505 (<i>ΔroxS</i> + empty vector) and CCB498 (<i>ΔroxS</i> + pDG-Ptet-roxS) at times after the addition of 40 μg/mL aTc. The blot was re-probed for 16S rRNA (oligo CC058; <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004957#pgen.1004957.s012" target="_blank">S4 Table</a>) as a loading control. (B) Same as panel A using RNase III mutant strains CCB530 (<i>ΔroxS Δrnc</i> + empty vector) and CCB531 (<i>ΔroxS Δrnc</i> + pDG-Ptet-roxS). (C) Same as panel A using RNase Y mutant strains CCB535 (<i>ΔroxS Δrny</i> + empty vector) and CCB533 (<i>ΔroxS Δrny</i> + pDG-Ptet-roxS). The RNAs isolated from strains CCB498, CCB531 and CCB533 in panels A, B and C were also run on a polyacrylamide gel and probed for RoxS. (D) Quantification of RoxS and <i>ppnKB</i> in Northern blots of strains containing pDG-Ptet-roxS. Left: WT and <i>Δrnc</i> backgrounds; Right: WT and <i>Δrny</i> backgrounds. The WT traces are the average of three experiments, and the <i>Δrnc</i> and <i>Δrny</i> traces are the average of two experiments, with standard errors as shown. <i>ppnKB</i> mRNAs were normalized to 16S rRNA and to the T0 sample (right hand Y-axis). RoxS was normalized to either 16S or 5S rRNA (left hand Y-axis).