  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.
