Fig. 6
Effect of the smart library of sRNA-based stress circuits on cell growth and protein production of a membrane targeted sfGFP (SohB(TMD)-sfGFP). The strain which expressed construct SohB(TMD)-sfGFP without stress circuit, was used as reference (R). The strain with native cpxQ served as negative control (N). Expression of sfGFP in the cytoplasm was also included (Cy). a OD600 measured in time. b sfGFP/OD600-values of the different strains (inducer concentration 0.2 mM IPTG). sfGFP/OD600 values for an equal number (OD600 = 0.25) of E. coli MG1656 DE3 cells were plotted. This ratio was corrected for background fluorescence and optical density of the medium and the cell culture (Escherichia coli MG1656 DE3). c Maximum specific growth rate (µmax) of the different strains. The experiment was carried out in triplicate (biological variation) and the error bars represent one standard deviation from the mean value. For panel b and c, significant differences between strains expressing construct SohB(TMD)-sfGFP and all constructs with native or mutated cpxQ were calculated using one-way ANOVA. d Scatter plot representing fold change of sfGFP in function of the ΔG2 absolute value for the secondary sRNA structure (Timepoint: 10 h, stationary phase). Complete plasmid details can be found in Additional file 1: Table S6. The colormaps represents the ΔG1 absolute value. * = p-value < 0.05, ** = p-value < 0.01, *** = p-value < 0.001, ΔG1 Gibbs free energy for sRNA-mRNA interaction, ΔG2 Gibbs free energy for sRNA stability, sfGFP superfolder green fluorescent protein, SohB(TMD) transmembrane domain of inner-membrane protein SohB from E. coli, TIR translation initiation region