Electronic Implementation of a Repressilator with Quorum Sensing Feedback

Edward H Hellen,Evgeny Volkov,Syamal K Dana,Boris Zhurov,Jordi Garcia-Ojalvo

doi:10.1371/journal.pone.0062997

Abstract

We investigate the dynamics of a synthetic genetic repressilator with quorum sensing feedback. In a basic genetic ring oscillator network in which three genes inhibit each other in unidirectional manner, an additional quorum sensing feedback loop stimulates the activity of a chosen gene providing competition between inhibitory and stimulatory activities localized in that gene. Numerical simulations show several interesting dynamics, multi-stability of limit cycle with stable steady-state, multi-stability of different stable steady-states, limit cycle with period-doubling and reverse period-doubling, and infinite period bifurcation transitions for both increasing and decreasing strength of quorum sensing feedback. We design an electronic analog of the repressilator with quorum sensing feedback and reproduce, in experiment, the numerically predicted dynamical features of the system. Noise amplification near infinite period bifurcation is also observed. An important feature of the electronic design is the accessibility and control of the important system parameters.

Highlights

Biological networks such as transcriptional genetic networks and metabolic networks are complex in structure and dynamical behaviors [1]
Numerical Results We first present the numerical results of available dynamical regimes as stable steady state (SS) and limit cycle (LC) as calculated from Eq(1) using the XPPAUTO [27] for b1 = b2 = b3 = b = 0.1 and n = 3.3
Synthetic genetic oscillators are usually considered as prototypes of some natural genetic elements, or at least as motifs of genetic networks

Summary

Introduction

Biological networks such as transcriptional genetic networks and metabolic networks are complex in structure and dynamical behaviors [1]. We investigate how the dynamics of a single repressilator with QS feedback depends on k for a small value b = 0.1, which is close to biologically motivated value, and for the larger value b = 1 which assumes the same time scales for both the proteins and the mRNA.

Results

Conclusion