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

Figure 2

Quantification of growth variation in different E. coli strains under two physiological regimens. (a) Schematic representation of the main steps for gene expression in bacteria. The strength of the interaction between RNA polymerase (RNAP) and target promoter determines the rate of mRNA synthesis (β_m), while the RBS sequence determines the rate of protein translation (β_p). The rates of mRNA and protein dilution or degradation (γ_m and γ_p, resp.) depends on cell growth and physiological regimens of the cells. (b) Growth curve of E. coli strains harboring a Plac::GFPlva fusion in minimal medium with 1% glycerol (left) or 1%glycerol plus 0.4% glucose (right) as carbon source. (c) Growth curve of E. coli strains harboring different promoter fusions (Pj100, Pj106, Pj114, and Pj113) in minimal medium with 1% glycerol or 1%glycerol plus 0.4% glucose (labeled as glu) as carbon source. Solid lines represent average values calculated using data from three independent experiments for wild type (black), Δihf (red), and Δfis (green) strains, while dashed lines represent the upper and lower limits of standard deviations.

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