Negative feedbacks and topology of plasmid R388 transcriptional network.

<p>(<b>A</b>). Each panel shows the transcriptional activity (GFP/OD) (×10²) of a given promoter, either alone or in the presence of each of the six transcriptional repressors (ResP, KfrA, ArdK, StbA, TrwA and KorA). Repressors were produced from a co-residing expression vector pBAD33, and the negative control indicates the GFP/OD (×10²) values obtained in the presence of the empty vector. The upper diagrams show the location of each regulator with respect to its cognate promoter in plasmid R388 (<b>B</b>) A graphical representation of expression profiling data (shown in Supporting <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004171#pgen.1004171.s003" target="_blank">figures S3</a> and <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004171#pgen.1004171.s004" target="_blank">S4</a>) unveils the topology of the regulatory circuitry. Coloured arrows indicate the position of transcriptional regulators within plasmid R388 genome (ResP in orange, KfrA in blue, ArdK in purple, StbA in green, TrwA in red and KorA in navy blue). The regulatory links are coloured according to the same code. Red lines shown over the ORF map correspond to the transcriptional units identified in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004171#pgen-1004171-g002" target="_blank">Figure 2</a>.