Cells are controlled by molecular networks capable of sophisticated functions and dynamics. For example, cells receive a wide variety of internal and environmental signals that are integrated combinatorially at the level of gene expression. Using a statistical mechanics model of gene expression and invoking only specific protein-DNA interaction and weak "glue-like" interactions between regulatory proteins, the first half of my talk will demonstrate how combinatorial logic of increasing complexity can emerge.
Molecular networks in cells also exhibit important dynamical behaviors, such as bistability and oscillation. Sharp threshold responses in gene expression are an important feature for the emergence of such dynamics in gene networks. In biology, many regulatory molecules are titrated by an inhibitor into an inactive complex. Using an approach that combines both theory and experiment, I will demonstrate how molecular titration generates tunable thresholds in gene expression. These results suggest a simple nonlinear mechanism for the rapid evolution of bistability (e.g. memory) and oscillation (e.g. clocks) in molecular networks.
Lunch will be served in Room 298 before the colloquium.