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Tuning Promoter Strength through RNA Polymerase Binding Site Design in Escherichia coli

Figure 5

Gene expression as a function of RNAP binding energy.

(A) LacZ activity measured in Miller units and (B) average mRNA per cell vs. promoter binding energy in units of (with the zero of energy set to be the average interaction energy between RNAP and the the entire E. coli chromosome). To illustrate the reproducibility of our measurements, the translucent points represent individual measurements and the solid points represent the averaged value over repeated experiments. The solid black line in each plot is the Boltzmann factor scaling, . The red data points correspond to the wild-type lac promoter, which was used to calibrate the arbitrary units of our energy matrix to (physical) units. The magenta, red, blue, and green data points represent promoters which we examine in the context of simple repression.

doi: https://doi.org/10.1371/journal.pcbi.1002811.g005