On September 3, Derek Sherry successfully defended the thesis, “Lattice Ultrasensitivity: a new model for signal amplification in E. coli chemotaxis” (advisor: Ben Machta).
Sherry explained, “My thesis focused primarily on developing a new model to describe the sensory system used by E. coli to navigate their environments. Sensory systems play vital roles throughout biology. This work draws connections between the bacterial sensory system and other well known physical systems, and provides new insights into how bacteria process information.”
Sherry continued, “I don’t yet have any concrete positions lined up yet. The first thing I’m gonna do is go backpacking in Colorado for three weeks.”
Thesis abstract
Signal processing is vital to many biological systems. The signal transduction network in E. coli chemotaxis is an important test case for such biochemical signal processing. In this thesis, I introduce a new model for this signaling, driven from equilibrium reactions between neighboring units in an extended signaling array. The model can achieve arbitrarily high gain through time-scale separation, without the need for fine-tuning, and it also captures qualitative experimental results which are difficult to reconcile with existing models. I also begin the development of some possible molecular implementations of the model where long flexible linkers could potentially mediate interactions between neighboring core units in the signaling lattice. Finally, I determine the critical exponents of the model and describe its relationship to the voter model and the Ising universality class.