Effects of Molecular Noise on the Multistability in a Synthetic Genetic Oscillator

Abstract

We used 3-genes genetic oscillator as a model of oscillators coupled with quorum sensing, implemented as the production of a diffusive molecule, autoinducer. The autoinducer stimulates expression of the target gene within the oscillator’s core, providing a positive feedback. Previous studies suggest that there is a hysteresis in the system between oscillatory (OS) and stationary (SS) dynamical solutions. We question the robustness of these attractors in presence of molecular noise, existing due to small number of molecules in the characteristic processes of gene expression. We showed distributions of return times of OS near and within the hysteresis region. The SS is revealed by the return times duration increase as the system approaches hysteresis. Moreover, the amplitude of stochastic oscillations is larger because of sensitivity of the system to the steady state even outside of the hysteresis. The sensitivity is caused by the stochastic drift in the parameter space.