Basal values for the parameters and concentrations of the models in Figure 1.

aThese values were chosen in such a way that the affinity of the TCS proteins with the third component would be similar to the affinity between the SK and the RR. bThe value for this parameter was chosen to be one order of magnitude larger than that representing SK autodephosphorylation, because the TCSK enhances SK autodephosphorylation. cTC SK total is the total amount of the third component in Model B. This third component protein binds the SK of the TCS module. The amount for this protein was chosen taking into account that basal mRNA levels for RetS in GEO micro profiles of Pseudomonas aeruginosa are between 2 and 10 times higher than those of GacS. GacS is an SK and RetS is its cognate TCSK[47]. dTC RR total is the total amount of the third component in Model C. This third component protein binds the phosphorylated RR of the TCS module. The amount for this protein was chosen to be in the same order of magnitude as that of the RR, as is done in reference [43]. eThis is the average value for the autophosphorylation catalytic constant between Salmonella typhimurium and Escherichia coli [16]. fIt should be noted that, for Model C, this value for the phosphatase rate constant could be as high as 0.14 in Escherichia coli [16]. gAlthough some measurements have suggested that the affinity between non-phosphorylated forms of the SK and RR is much lower than the affinity between phosphorylated forms of the proteins [48], more recent measurements suggest the opposite [10].