Title: Receptor cross talk and signal amplification: some recent results on signal transduction in bacterial chemotaxis
Speaker: Yuhai Tu, IBM Research
Date: Wednesday, January 28, 2004 1:00 pm
Location: Hill Center, Room 260, Rutgers University, Busch Campus, Piscataway, NJ
We propose a general framework for modeling kinase activity in bacterial chemotaxis signaling pathway, the model explicitly includes the effects of covalent receptor modification and interaction between neighboring chemoreceptors on the kinase activity of the receptor complex. We show that our model can quantitatively explain the recent in vivo measurements of the receptor sensitivity at different ligand concentrations for both the mutant and the wild type strains. For the mutant strains, our model can fit the experimental data exactly. For the wild type cell, our model is capable of achieving high gain while having modest values of Hill coefficient for the response curves. Furthermore, the high sensitivity of the wild type cell in our model is maintained for a wide range of ambient ligand concentrations, facilitated by near perfect adaptation and dependence of ligand binding on receptor activity. Our study reveals the importance of coupling between different chemoreceptor species, in particular strong interactions between the aspartate (Tar) and serine (Tsr) receptors, which is crucial in explaining both the mutant and the wild type data. Predictions for the sensitivity of other mutant strains and possible improvements of our model for the wild type cell are also discussed.
Seminar sponsored by DIMACS/BIOMAPS Seminar Series on Quantitative Biology and Epidemiology.