Calibrating Transcriptional Activity Using Constitutive Synthetic Promoters in Mutants for Global Regulators in Escherichia coli

Figure 4

The calibrator can be applied to the induction system xylS-Pm. (a) xylS promoters (PxylS), xylS protein, and Pm promoter were cloned into the plasmid pMR1, which contains a short-lived GFP variant. (b) xylS-Pm calibration in LB solid medium with 1000 μM of 3MBz added. This calibration was performed in BW25113 wt strains. (c) Pjx promoter activity analyzed by 8 hours of experiment by monitoring GFPlva expression using pMR1 constructions. (d) GFP expression profile for 7 different 3MBz concentrations for Pjx and xylS-Pm in pMR1 vector, 4.5 hours after the induction. Solid lines represent the average values calculated using data from three independent experiments for wild type, Δihf, and Δfis strains, while dashed lines represent the upper and lower limits of standard deviations.

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