Sigma factor-mediated tuning of bacterial cell-free synthetic genetic oscillators

Maaruthy Yelleswarapu, A.J. van der Linden, P.A. Pieters, E. Dubuc, T.F.A. de Greef, Wilhelm T.S. Huck

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23 Citations (Scopus)
124 Downloads (Pure)


Cell-free transcription-translation provides a simplified prototyping environment to rapidly design and study synthetic networks. Despite the presence of a well characterized toolbox of genetic elements, examples of genetic networks that exhibit complex temporal behavior are scarce. Here, we present a genetic oscillator implemented in an E. coli-based cell-free system under steady-state conditions using microfluidic flow reactors. The oscillator has an activator-repressor motif that utilizes the native transcriptional machinery of E. coli: the RNAP and its associated sigma factors. We optimized a kinetic model with experimental data using an evolutionary algorithm to quantify the key regulatory model parameters. The functional modulation of the RNAP was investigated by coupling two oscillators driven by competing sigma factors, allowing the modification of network properties by means of passive transcriptional regulation.

Original languageEnglish
Pages (from-to)2879-2887
Number of pages9
JournalACS Synthetic Biology
Issue number12
Publication statusPublished - 8 Nov 2018


  • cell-free systems
  • competition-induced regulation
  • oscillator
  • sigma factors
  • synthetic biology
  • DNA-Directed RNA Polymerases/genetics
  • Algorithms
  • Synthetic Biology/methods
  • Cell-Free System
  • Sigma Factor/genetics
  • Escherichia coli/genetics
  • Gene Expression Regulation, Bacterial


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