Figure 2.
Polyproteins as modular units to control genetic circuits. For all figures, the left panel shows a schematic diagram of the system and the right panel shows the corresponding response functions for the two outputs. Constitutively expressed TVMVp cleaves the polyprotein in two functional subunits in all cases. Cells containing a plasmid encoding a given polyprotein design expressed from a PJ23115 constitutive promoter and a Ptac-inducible protease in a separate plasmid were exposed to different concentrations of IPTG for 6 h. The resulting GFP and RFP fluorescences were measured using flow cytometry. For all of the panels, red lines-squares indicate RFP fluorescence and green lines-triangles indicate GFP fluorescence. (A) Simultaneous controlled degradation of TetR and PhlF by TEV protease in cells containing pPoly-Deg and pTac-TEV. (B) Simultaneous release of TetR and PhlF by SuMMV protease in cells containing pPoly-Rel and pTac-Su. (C) Simultaneous degradation and release of TetR and PhlF by TEV and SuMMV proteases, respectively, in cells containing pPoly-Switch and pTac-TEV-Su. The colored squares represent the same parts as in Figure 1C and D. In all figures, error bars correspond to the standard deviation of three experiments performed on different days.