Guy Shinar (Uri Alon's Group, Molecular Cell Biology & Physics of Complex Systems, Weizmann Institute of Science)
Thursday, 9.7.2009, 13:30
Cell-to-cell and temporal variations in the concentrations of biomolecular components are inevitable. These variations in turn propagate along networks of chemical reactions to impart changes in the concentrations of still other species, such as phosphorylated transcription factors, that influence biological activity. Because excessive variations in the levels of certain active molecules might sometimes be deleterious to cell function, regulation systems have evolved that act to maintain concentrations within tight bounds. Although the mechanistic basis of such regulation is known in specific cases, a general description of network features that give rise to concentration homeostasis is lacking. Here we identify simple yet subtle structural attributes that impart absolute concentration robustness to any mass action network possessing them. We thereby describe a large class of robustness-inducing networks that already embraces a variety of quite different biochemical modules for which concentration robustness has been observed experimentally. These include the E. coli signaling system EnvZ/OmpR, and the glyoxylate bypass control system IDHKP/IDH.
In collaboration with Martin Feinberg, Ohio State University.