Figure 6

Dynamical behavior of Network IV. (A) Average number of GFP molecules in the absence of Tc (WT w/o Tc, blue line) and when 2000 molecules (WT/w 2000 Tc, green line) or 5000 molecules (WT/w 5000 Tc, red line) of Tc are added into the medium at time 5 × 10⁴ sec, using wild-type kinetics. (B) Average number of GFP molecules in the absence of Tc, using wild-type kinetics (WT w/o Tc, blue line), a 10 fold (Des 4.1 w/o Tc, green line) and a 20 fold (Des 4.2 w/o Tc, red line) increase in the dissociation constant of TetR from all TetO in the network(mutated TetR variant, less affinity for TetO). (C) Average number of GFP molecules when 5000 molecules of Tc are added into the medium at time 5 × 10⁴ sec, using wild-type kinetics (WT/w 5000 Tc, blue line) and mutated TetR variant that does not bind Tc (Des 4.3/w 2000 Tc, green line). (D) Average number of GFP molecules when 5000 molecules of Tc are added into the medium at times 2 × 10⁴ sec and 6 × 10⁴ sec, using a mutated TetR variant that does not bind Tc and also shows different levels of binding affinity for TetO, 10 fold (Des 4.4/w 2000 Tc (x2), blue line), 20 fold (Des 4.5/w 2000 Tc (x2), green line) and 50 fold (Des 4.6/w 2000 Tc (x2), red line) decrease in the dissociation constant.