Change in conc. of membrane phoP Simulation plot capturing the effects of varying diffusion rates on phoP. An interesting observation, not captured in the wet-test lab results, is the orchestration of the positive feedback loop of phoP, as identified in the knowledge extraction phase. As seen in this figure, the concentration of phoP in the system decreases initially; but once the expression of genes is triggered by phoPp (phosphorylated phoP), phoP starts appearing in the system. The corresponding effect on phoPp, which increases in concentration when Mg2+ depart from the membrane (activating the pathway) is captured in Figure 14. In both the graphs, the slowest diffusion rate does not bring the system into resource shortage phases while the other diffusion rates lock the system (plateau on Figure 14) due to non-availability of phoPp molecules. These graphs show how the tuning of different parameters (in the diffusion rates) can be synthetically manipulated to study different behaviors of the systems.
Ghosh et al. BMC Genomics 2010 11(Suppl 3):S3 doi:10.1186/1471-2164-11-S3-S3