Fig 1.
Regulation of alx expression by PRE in response to an increased external pH and [Mn2+]. (A and C) β-galactosidase activities (in Miller units) of mid-log phase grown cultures of ∆alx::Kan derivatives of MC4100 strain of E. coli (RAS31) carrying one of the following plasmids: promoter-less vector with lacZ (pMU2385), transcriptional reporter of mntP (PmntP-5′UTR-mntP′-lacZ, pRA48), transcriptional reporter of alx (Palx-PRE-alx′-lacZ, pRA40), or ∆PRE derivative of alx transcriptional reporter (Palx-alx′-lacZ, pRA41). The above cultures were cultivated in LBK media pH 6.8 or pH 8.4 (panel A) and LB pH 6.8 with and without supplemented MnCl2 (panel C). (B and D) β-galactosidase activities of mid-log phase grown cultures of ∆alx::Kan derivatives of MC4100 strain of E. coli (RAS31) carrying one of the following plasmids: promoter-less vector with lacZ (pMU2386), translational reporter of mntP (PmntP-5′UTR-mntP′-lacZ, pRA57), translational reporter of alx (Palx-PRE-alx′-lacZ, pRA54), or ∆PRE derivative of alx translational reporter (Palx-alx′-lacZ, pRA55). The above cultures were grown in LBK media pH 6.8 or 8.4 (panel B) and LB pH 6.8 with and without supplemented MnCl2 (panel D). A combined effect of alkaline pH and supplemented MnCl2 on translational reporters in LBK media pH 6.8 or LBK media pH 8.4 supplemented with MnCl2 is illustrated in panel E. Each plotted value in a bar graph with standard error of mean (SEM) is an average of three biological replicates of the experiment. The statistical significance of the changes in the reporter signal with growth conditions was assessed by two-way ANOVA (nsP > 0.05, **P < 0.01, ***P < 0.001).