Research - Theoretical Biophysics



Our group aims to understand the fundaments of several intra- and extra- cellular processes:

Bacterial Cell Division: Like all other living organisms, bacterial cells constantly reproduce themselves via division. This process is crucial, complex and is subject to precise regulation. It typically involves a mechanochemical machinery to generate the force, and multiple regulatory systems to monitor, supervise and control the operation of this dedicated mechanochemical machine. We currently focus on the “simple” bacterium, E. coli, to study how the dynamical dividing process is defined, regulated and coordinated. We employ and develop methodologies from physics, statistical mechanics as well as continuum mechanics and integrate many biological details to construct molecular models and our ultimate goal is to obtain system level quantitative understanding of E. coli cell division.

Thermodynamics of Biological Regulator: Biological systems are precisely regulated by various molecular networks. As more and more such networks have been identified, we have much better idea about how different interaction topologies among molecules give rise to desired regulatory functions. However, we have been long missing the other side of the story: what drives these networks? Close inspection of many networks show that energy bearing molecules (e.g. ATP, GTP, SAM, etc.) are always involved and help drive so called “futile” cycles. It is evident that biological regulation consumes energy. We want to extend this conceptual conclusion to quantitative level and understand how the networks’ performance relates to networks’ energy cost. Interesting, some existing models for a few biological systems do not involve energy input yet still give rise to regulatory functions. We want to validate these models from a thermodynamic standpoint.

Eukaryotic Cell Physics: Physical properties of eukaryotic cells have been bridged to the cells’ function, well-being and fate. For example, tumor cells have been shown to have different migration potentials comparing to healthy cells. While migrating, cell alters between two stages of motion (“fast” persistent movements and direction-changing pauses) and during the persistent motion, the cell’s leading edge often oscillates (e.g. on stiff substrate). More importantly, cell oscillation has been observed in many cellular processes other than migration, including the embryo development and differentiation process. We want to integrate cell mechanics with biochemical regulation to explore the eukaryotic cell oscillation as well as other biophysical phenomena.