Figure 2

Model of the gal system in E. coli. A: View of the gal system in E. coli. The activator CRP activates both galETK and GalS. GalS inhibits galETK and negatively auto-regulates itself. GalS _inh , which is a shortcut representing both β-D-galactose and D-fucose, cancels the inhibitory effect of Gals _S on galETK. B: Evolution of the level of galETK when CRP is activated at time t = 0. The level are represented using relative values with respect to the stable state galETK _St . The situation in which no GalS _inh is not expressed is represented in blue. This corresponds to an I1-FFL. The situation in which GalS _inh is present is represented in red. In this situation, the model behaves like with a simple activation. The response time, measured as the time needed to reach galETK _St /2 is shorter in the absence of GalS _inh .