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. 2016 Jul 20;44(20):9650–9666. doi: 10.1093/nar/gkw642

Figure 2.

Figure 2.

Transcription of OmrA and OmrB sRNAs is strongly dependent on EnvZ-OmpR TCS. (A) The effect of various mutants in envZ or ompR on OmpR phosphorylation in vivo was analyzed by western blot following protein separation in presence of Phos-Tag. Samples were taken from strains DJ480 (wt), MG1670 (envZ390), MG1671 (envZ473), MG1672 (ompR107), MG1673 (ompR472) and MG1035 (ΔompR::cm) grown in LB to exponential phase, before or after addition of 10 mM procaine for 10 min. A non-specific band obtained from cross-hybridization with an anti-EF-Tu antibody is shown as a loading control. (B) The activation of promoter fusions to omrA, omrB, ompC or ompF was calculated as the ratio between the activity of those fusions in ompR+ and ompR− strains. The average and the standard deviations from at least two independent experiments are shown. Strains used here are, for ompR+ and ompR− respectively, MG1004 and MG1811 (PomrA fusion), MG1005 and MG1812 (PomrB fusion), MG1863 and MG1891 (PompC fusion) and MG1690 and MG1810 (PompF fusion). In this experiment, the β-galactosidase activities in the ompR+ strain were, in Miller units, 19.1 (PomrA fusion), 49.4 (PomrB), 6010 (PompC) and 3270 (PompF). (C) The β-galactosidase activity of the same promoter fusions in wt strains or in the same set of envZ-ompR mutants used in (A) was measured in LB medium in exponential phase. wt, envZ390, envZ473, ompR107 and ompR472 strains are respectively MG1892, MG1893, MG1894, MG1895 and MG1896 (PompC fusion), MG1690, MG1692, MG1694, MG1696, MG1698 (PompF fusion), MG1004, MG1299, MG1300, MG1301, MG1302 (PomrA fusion) and MG1005, MG1303, MG1304, MG1305 and MG1306 (PomrB fusion). Numbers above the bars indicate repression- or activation-fold (in gray or black respectively) in expression relative to the wt strain; note that right-hand panel uses log scale.