Quantifying second-messenger information transmission in bacteria

Abstract

Bacterial second messengers are crucial for transmitting environmental information to cells. However, quantifying their information transmission capacity remains challenging. Here we develop a framework for quantifying information processing in cellular signalling systems. We engineer an isolated cyclic adenosine monophosphate (cAMP) signalling channel in Pseudomonas aeruginosa using targeted gene knockouts, optogenetics and a fluorescent cAMP probe. This design enables precise optical control and real-time monitoring of cAMP dynamics. By integrating experimental data with information theory, we reveal the optimal frequency for light-mediated cAMP signalling that maximizes information transmission, reaching about 40 bits per hour. This rate correlates strongly with cAMP degradation kinetics and uses a two-state encoding scheme. Our findings suggest a mechanism for fine-tuned regulation of multiple genes through temporal encoding of second-messenger signals, providing insights into bacterial adaptation strategies. Bacterial second messengers carry signals from the environment to target proteins in the cell. Now the associated information transmission capacity is quantified and the optimal frequency to maximize it is determined.