Dresden 2017 – scientific programme
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BP: Fachverband Biologische Physik
BP 4: Systems Biology & Gene Expression and Signalling
BP 4.5: Talk
Monday, March 20, 2017, 16:15–16:30, ZEU 250
Engineering orthogonal synthetic timer circuits in bacteria — •Marco Mauri1, Daniela Pinto2, Stefano Vecchione1, Hao Wu1, Thorsten Mascher2, and Georg Fritz1 — 1LOEWE-Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Germany — 2Institut für Mikrobiologie, Technische Universität Dresden, Germany
The rational design of synthetic circuits in bacteria is often restricted by cross-reactions between circuit components and physiological processes within the heterologous host. Here, we present a strategy to overcome these restrictions by using extracytoplasmic function sigma factors (ECFs). These are reversible binding subunits of the bacterial RNA polymerase, which are activated upon environmental stress conditions. ECFs represent ideal orthogonal regulators because there exist over 90 phylogenetic ECF groups recognizing distinct target promoters. To explore their potential for synthetic circuit design, we evaluate several heterologous ECFs in Escherichia coli and Bacillus subtilis. After a quantitative study of simple switches, we use a computational model to predict the behaviour of a cascade with two and three ECFs, which we find in excellent agreement with experimental data. We show that in both organisms these "autonomous timers" sequentially activate a series of genes with a defined time delay. These results not only serve as a proof of concept for the application of ECFs as organism-independent building blocks for synthetic biology, but could also be used to introduce a timing hierarchy among the expression of biosynthetic pathway components in biotechnological applications.