FIGURE 4.

Transfer functions of recombinant strains with HSL-inducible dCas9 and constitutive sgRNA. Transfer curves, with RFP as output, are reported as a function of HSL. Data are shown as the average RFP synthesis rate per cell. In each panel, the copy number of the sgRNA constitutive cassette (low copy—LC, medium copy—MC) and the copy number of the target (medium copy—MC, high copy—HC) are reported. Two different targeting systems [Tet—panels (A,C,E), and Lac—panels (B,D,F)] are reported: gPtet and gPlac, which repress the P_LtetO1 and P_LlacO1 promoters, respectively, that drive RFP. Each panel includes four curves: three of them correspond to circuits with the sgRNA under the control of three different constitutive promoters of diverse strengths (weak, medium and strong for J23116, J23100 and J23119, respectively), and one curve corresponds to a non-specific targeting control in which the medium-strength J23100 promoter constitutively transcribes a non-targeting sgRNA: gPlac and gPtet for the P_LtetO1 and P_LlacO1 promoters in the Tet and Lac systems, respectively. Data points represent the average value and error bars represent the standard errors of the mean of at least three independent experiments.