Optimization of information transmission through a noisy biochemical pathway explains the choice of reaction rates

Living organisms are required to sense the environment accurately in order to ensure appropriate responses. The cells utilize specific signaling pathways to estimate the signal. The accuracy of estimating the input signal is severely limited by noise stemming from inherent stochasticity of the chemical reactions involved in signaling pathways. Cells employ multiple strategies to improve the accuracy by tuning the reaction rates, for instance amplifying the response, reducing the noise etc.. However, the pathway also consumes energy through incorporating ATP in phosphorylating key signaling proteins involved in the reaction pathways. In many instances, improvements in accuracy elicit extra energetic cost. For example, higher deactivation rate suppresses the basal pathway activity effectively amplifying the dynamic range of the response which leads to improvement in accuracy. However, higher deactivation rate also enhances the energy dissipation rate. Here, we employed a theoretical approach based on non-equilibrium thermodynamics of information to explore the role of accuracy and energetic cost in the performance of a MAPK signaling system. Our study shows that the accuracy-energy trade-off can explain the optimality of the reaction rates of the reaction pathways rather than accuracy alone. Our analysis elucidates the important role of the interplay between accuracy and related energetic cost in evolutionary shaping of the parameter space of signaling pathways.