Switchable Genetic Oscillator Operating in Quasi-Stable Mode

TL;DR

This paper reveals that even repressilator gene circuits can exhibit long-lived, quasi-stable oscillations in stochastic environments, enabling controlled switching between oscillatory and stable states.

Contribution

It introduces the concept of quasi-stable, traveling-wave solutions in even gene rings, explaining sustained oscillations and enabling reliable control of gene circuit dynamics.

Findings

Even repressilators have long-lived, quasi-stable oscillatory solutions.

These solutions explain sustained oscillations in stochastic regimes.

A simple optical interference protocol can reliably induce oscillations.

Abstract

Ring topologies of repressing genes have qualitatively different long-term dynamics if the number of genes is odd (they oscillate) or even (they exhibit bistability). However, these attractors may not fully explain the observed behavior in transient and stochastic environments such as the cell. We show here that even repressilators possess quasi-stable, travelling-wave periodic solutions that are reachable, long-lived and robust to parameter changes. These solutions underlie the sustained oscillations observed in even rings in the stochastic regime, even if these circuits are expected to behave as switches. The existence of such solutions can also be exploited for control purposes: operation of the system around the quasi-stable orbit allows us to turn on and off the oscillations reliably and on demand. We illustrate these ideas with a simple protocol based on optical interference that can induce oscillations robustly both in the stochastic and deterministic regimes.