DEPICT · Design principles and controllability of protein circuits

Cells use circuits of interacting proteins to respond to their environment. In the past decades, molecular biology has provided detailed knowledge on the proteins in these circuits and their interactions. To fully understand circuit function requires, in addition to molecular knowledge, new concepts that explain how multiple components work together to perform systems level functions. Our lab has been a leader in defining such concepts, based on combined experimental and theoretical study of well characterized circuits in bacteria and human cells. In this proposal we aim to find novel principles on how circuits resist fluctuations and errors, and how they can be controlled by drugs: (1) Why do key regulatory systems use bifunctional enzymes that catalyze antagonistic reactions (e.g. both kinase and phosphatase)? We will test the role of bifunctional enzymes in making circuits robust to variations in protein levels. (2) Why are some genes regulated by a repressor and others by an activator? We will test this in the context of reduction of errors in transcription control. (3) Are there principles that describe how drugs combine to affect protein dynamics in human cells? We will use a novel dynamic proteomics approach developed in our lab to explore how protein dynamics can be controlled by drug combinations. This research will define principles that unite our understanding of seemingly distinct biological systems, and explain their particular design in terms of systems-level functions. This understanding will help form the basis for a future medicine that rationally controls the state of the cell based on a detailed blueprint of their circuit design, and quantitative principles for the effects of drugs on this circuitry.