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A synthetic oscillatory network of transcriptional regulators


Networks of interacting biomolecules carry out many essential functions in living cells1, but the ‘design principles’ underlying the functioning of such intracellular networks remain poorly understood, despite intensive efforts including quantitative analysis of relatively simple systems2. Here we present a complementary approach to this problem: the design and construction of a synthetic network to implement a particular function. We used three transcriptional repressor systems that are not part of any natural biological clock3,4,5 to build an oscillating network, termed the repressilator, in Escherichia coli. The network periodically induces the synthesis of green fluorescent protein as a readout of its state in individual cells. The resulting oscillations, with typical periods of hours, are slower than the cell-division cycle, so the state of the oscillator has to be transmitted from generation to generation. This artificial clock displays noisy behaviour, possibly because of stochastic fluctuations of its components. Such ‘rational network design’ may lead both to the engineering of new cellular behaviours and to an improved understanding of naturally occurring networks.

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Figure 1: Construction, design and simulation of the repressilator.
Figure 2: Repressilation in living bacteria.
Figure 3: Examples of oscillatory behaviour and of negative controls.


  1. Bray, D. Protein moelcules as computational elements in living cells. Nature 376, 307–312 (1995).

    Article  ADS  CAS  PubMed  Google Scholar 

  2. Koshland, D. E. Jr The era of pathway quantification. Science 280, 852–853 ( 1998).

    Article  PubMed  Google Scholar 

  3. Winfree, A. T. The Geometry of Biological Time (Springer, Berlin, 1990).

    MATH  Google Scholar 

  4. Goldbeter, A. Biochemical Oscillations and Cellular Rhythms (Cambridge Univ. Press, 1996).

    Book  Google Scholar 

  5. Thomas, R. & D'Ari, R. Biological Feedback (CRC Press, Boca Raton, 1990).

    MATH  Google Scholar 

  6. Lutz, R. & Bujard, H. Independent and tight regulation of transcriptional units in Escherichia coli via the LacR/O, the TetR/O and AraC/I1-I2 regulatory elements. Nucleic Acids Res. 25, 1203–1210 (1997).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Kushner, S. R. in Escherichia Coli and Salmonella: Cellular and Molecular Biology (ed. Neidhardt, F. C.) (ASM, Washington DC, 1996).

    Google Scholar 

  8. Keiler, K. C., Waller, P. R. & Sauer, R. T. Role of a peptide tagging system in degradation of proteins synthesized from damaged messenger RNA. Science 271, 990–993 (1996).

    Article  ADS  CAS  PubMed  Google Scholar 

  9. Gottesman, S., Roche, E., Zhou, Y. & Sauer, R. T. The ClpXP and ClpAP proteases degrade proteins with carboxy-terminal peptide tails added by the SsrA-tagging system. Genes Dev. 12, 1338–1347 (1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Herman, C., Thevenet, D., Bouloc, P., Walker, G. C. & D'Ari, R. Degradation of carboxy-terminal-tagged cytoplasmic proteins by the Escherichia coli protease HflB (FtsH). Genes Dev. 12, 1348–1355 ( 1998).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Andersen, J. B. et al. New unstable variants of green fluorescent protein for studies of transient gene expression in bacteria. Appl. Environ. Microbiol. 64, 2240–2246 ( 1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  12. McAdams, H. H. & Arkin, A. It's a noisy business! Genetic regulation at the nanomolar scale. Trends Genet. 15, 65–69 (1999).

    Article  CAS  PubMed  Google Scholar 

  13. Bryson, J. W. et al. Protein design: a hierarchic approach. Science 270, 935–941 ( 1995).

    Article  ADS  CAS  PubMed  Google Scholar 

  14. Dunlap, J. C. Molecular bases for circadian clocks. Cell 96, 271–290 (1999).

    Article  CAS  PubMed  Google Scholar 

  15. Kondo, T. et al. Circadian rhythms in rapidly dividing cyanobacteria. Science 275, 224–227 ( 1997).

    Article  CAS  PubMed  Google Scholar 

  16. Barkai, N. & Leibler, S. Circadian clocks limited by noise. Nature (submitted????). (Eds to update)

  17. Tsien, R. Y. The green fluorescent protein. Annu. Rev. Biochem. 67, 509–544 (1998).

    Article  CAS  PubMed  Google Scholar 

  18. Glascock, C. B. & Weickert, M. J. Using chromosomal lacIQ1 to control expression of genes on high-copy-number plasmids in Escherichia coli. Gene 223, 221– 231 (1998).

    Article  CAS  PubMed  Google Scholar 

  19. Elowitz, M. B. Transport, Assembly, and Dynamics in Systems of Interacting Proteins. Thesis, Princeton Univ., Princeton (1999).

    Google Scholar 

  20. Gillespie, D. T. Exact stochastic simulation of coupled chemical reactions. J. Phys. Chem. 81, 2340–2361 ( 1977).

    Article  CAS  Google Scholar 

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We thank H. Bujard, S. Freundlieb, A. Hochschild, R. Lutz and C. Sternberg for plasmids and advice; U. Alon, N. Barkai, P. Cluzel, L. Frisen, C. Guet, T. Hyman, R. Kishony, A. Jaedicke, P. Lopez, F. Nédélec, S. Pichler, R. Kishony, T. Silhavy, T. Surrey, J. Vilar, C. Wiggins and E. Winfree for discussions; M. Surette for advice and encouragement; L. Hartwell and C. Weitz for comments on the manuscript; and F. Kafatos and E. Karsenti for hospitality and support at the European Molecular Biology Laboratory (EMBL), where part of this work was done. This work was partly supported by the US National Institutes of Health and the von Humboldt Foundation.

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Correspondence to Michael B. Elowitz.

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Elowitz, M., Leibler, S. A synthetic oscillatory network of transcriptional regulators. Nature 403, 335–338 (2000).

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