Cut up to bring together

Burgess, Darren J.

doi:10.1038/nrg3738

Research Highlight
Published: 08 May 2014

Synthetic biology

Cut up to bring together

Darren J. Burgess

Nature Reviews Genetics volume 15, page 365 (2014)Cite this article

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Prindle et al. used Escherichia coli strains engineered with a range of transcriptional gene modules that express reporter genes. They sought to temporally couple the expression of green fluorescent protein (GFP) and cyan fluorescent protein (CFP) reporter gene modules that were present in the same cells but that were driven by different inducible promoters. Previous attempts to synchronize such modules have used crosstalk at the transcriptional or translational levels, but have resulted in a substantial lag time (~30 minutes) between peaks of expression of the two reporters. Instead, the authors engineered Leu-Ala-Ala sequences into the carboxy-termini of both fluorescent proteins so that they competed for proteolytic degradation by the E. coli ClpXP protease. This coupling at the post-translational level resulted in tight synchronization of expression (~1-minute difference between GFP and CFP expression peaks).

The investigators then turned to more complex gene modules in which the promoter drives a negative-feedback regulator in addition to the fluorescent reporter gene, which results in oscillating gene expression. An oscillating GFP module — which had components derived from the intercellular quorum-sensing system that were also Leu-Ala-Ala tagged — successfully conferred colony-wide oscillating expression on the previously non-oscillating CFP module described above. Interestingly, this coupling could be 'tuned': engineering Thr-Ser spacers before the Leu-Ala-Ala tag in CFP increased the lag time between GFP and CFP expression peaks.

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