Effect of cell-to-cell variability on the signal transduction capability of an isogenic population

Cells of an isogenic population display significant cell-to-cell variability in sensing capabilities because of variation in protein abundances. With E.Coli chemosensory signaling pathway as our model system, we addressed the general question of how the nonlinear signal transduction capabilities of a diverse population and those of the mean phenotype differ and what are the physiological implications. Using data assimilation techniques we fit the standard nonlinear model of chemotaxis to the response of individual E.Coli cells measured using single cell FRET and characterized the phenotypic diversity in chemosensing capabilities by extracting the parameter values of the model. Visualizing the population in the high-dimensional parameter space gives insight about the different sensing strategies used by the clonal population and correlations among the parameters sheds light on the constraints imposed by regulatory processes. Finally, by analyzing the simulated response of models extracted by measuring hundreds of cells, we explore how variability shapes the signaling transduction capabilities of the diverse population.