Functional robustness of the large scale genetic regulatory network of E. coli

The accumulation of molecular interaction data for a large fraction of genes (more than 3000 of about 4500) of the bacterium Escherichia coli has enabled us to ask certain system level questions about the architecture and dynamics of its regulatory network. The talk will discuss the structure of the large scale transcriptional regulatory network of E. coli. A coarse grained mathematical model for the on-off dynamics of the genes regulating metabolism will be presented. An analysis of the attractors of this Boolean dynamical system shows that the on-off configurations of the genes are robust against transient perturbations of the cell, but are responsive to sustained changes in the external environment. This provides insight into the twin properties of cellular homeostasis and the adaptability of the cell to environmental changes. Preliminary results of a more detailed model of the core of the genetic regulatory network will also be described.