My laboratory combines optical microscopy of living cells and single molecules with biochemistry and mathematical modeling to understand the function of small networks of strongly interacting biological molecules. These projects are motivated by the belief that explaining the origin of systems pr...
My laboratory combines optical microscopy of living cells and single molecules with biochemistry and mathematical modeling to understand the function of small networks of strongly interacting biological molecules. These projects are motivated by the belief that explaining the origin of systems properties such as robustness to perturbations and adaptation to changing input will require understanding the nature of the molecular events that comprise the interactions. To this end, we are interested in better understanding the intracellular environment in which biological systems function, including the role of subcellular localization, fluctuations in copy numbers of molecules, and changes in shared pools of metabolites. We are actively developing optical and biochemical tools to study and control these effects in vivo and in vitro, including superresolution imaging based on localization of single molecules (STORM), which permits the study of protein organization within microbial cells. We have recently been focused on a remarkable circadian clock found in photosynthetic cyanobacteria. This may be the simplest of all circadian clocks, as the core oscillator can be reconstituted in a test tube using three purified proteins (KaiA, KaiB and KaiC). The interactions between these proteins generate a stable %7E24-hour oscillation in the level of phosphorylated KaiC. We recently showed that phosphorylation occurs at two sites on KaiC and that the modification of these sites follows strong kinetic preferences. This pattern of multisite phosphorylation coupled to protein-protein interaction is sufficient to drive stable oscillations. We are studying the flow of timing information into the clock and the fidelity of information storage within the oscillator itself with the hope that the mechanisms employed here will have broad applicability throughout biology.