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. 2012 Jul 27;7(7):e41620. doi: 10.1371/journal.pone.0041620

Figure 5. Comparison of the strains with the promoters Pcat, Pcat -10CATTTA or Pcat -10CAGCCA expressing TetR.

Figure 5

(A) Dose-response curve of the promoter variants (PtetA gfp+ with Pcat/Pcat -10CATTTA/Pcat -10CAGCCA tetR) which were incubated with increasing dox concentrations. The control strains, Salmonella WT and the strain lacking TetR resulting in constitutive GFP expression (PtetA gfp+), were incubated without inducer or with 400 nM dox for maximum reporter activity. The bars illustrate the fluorescence intensity which was normalized to a 1 ml culture with OD595 = 0.5. The data are a representative set from at least three independent measurements and display the mean ± standard deviation. (B) Western blot analysis of the steady-state levels of TetR expressed either by Pcat, Pcat -10CATTTA or Pcat -10CAGCCA, detected with a polyclonal anti-TetR antibody. Salmonella WT and 20 ng of purified TetR served as controls. For each strain, 20 µg crude protein extracts were loaded (left panel). Additionally, 40 µg crude protein extract from the mutants Pcat -10CATTTA and Pcat -10CAGCCA were also analyzed (right panel). DnaK served as loading control in both blots and was detected with a monoclonal anti-DnaK antibody.