Non-equilibrium phase transitions in biomolecular signal transduction

TL;DR

This paper investigates how biomolecular signal transduction cascades achieve reliable switching through nonequilibrium phase transitions, despite stochastic molecular transitions, using theoretical models and reaction-diffusion methods.

Contribution

It introduces a unified theoretical framework to analyze phase transitions, noise, and switching dynamics in biomolecular systems with cooperative effects.

Findings

Bistable states emerge from cooperative effects in protein populations.

Switching behavior can be characterized as a nonequilibrium phase transition.

Critical properties of biomolecular switches are computable within the proposed models.

Abstract

We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework.