Role of functionality in two-component signal transduction: A stochastic study

We present a stochastic formalism for signal transduction processes in bacterial two-component system. Using elementary mass action kinetics, the proposed model takes care of signal transduction in terms of phosphotransfer mechanism between the cognate partners of a two-component system, viz, the sensor kinase and the response regulator. Based on the difference in functionality of the sensor kinase, the noisy phosphotransfer mechanism has been studied for monofunctional and bifunctional two component system using the formalism of linear noise approximation. Steady state analysis of both models quantifies different physically realizable quantities, e.g., variance, coefficient of variation, mutual information. The resultant data reveals that both systems reliably transfer information of extra-cellular environment under low external stimulus and at high kinase and phosphatase regime. We extend our analysis further by studying the role of two-component system in downstream gene regulation.