Phosphate Sink Containing Two-Component Signaling Systems as Tunable Threshold Devices
Figure 4
Effect of CheS on the signal-response curve.
The x- and y-axis show the ATP level and the corresponding steady state level of phosphorylated CheY2, respectively. The experimentally measured values are shown in circles (absence of CheS) and squares (presence of CheS). The phosphorylated CheY2 levels predicted by the model are shown with a dashed line (absence of CheS) and with a solid line (presence of CheS; where the CheA-P to CheY1 phosphotransfer reaction rate constant (ks) and CheY1-P dephosphorylation rate constant (khs) were optimized for best fit to the experimental data; ks = 50 and khs = 0.067). See Figure S6 for alternative fits to these experimental data where we have individually modelled the effect of CheS altering only ks or khs. Error bars show the standard error of the mean obtained from three independent experiments.