A pH-responsive genetic sensor for the dynamic regulation of D-xylonic acid accumulation in Escherichia coli


The xylose oxidative pathway (XOP) is continuously gaining prominence as an alternative for the traditional pentose assimilative pathways in prokaryotes. It begins with the oxidation of D-xylose to D-xylonic acid, which is further converted to α-ketoglutarate or pyruvate + glycolaldehyde through a series of enzyme reactions. The persistent drawback of XOP is the accumulation of D-xylonic acid intermediate that causes culture media acidification. This study addresses this issue through the development of a novel pH-responsive synthetic genetic controller that uses a modified transmembrane transcription factor called CadCΔ. This genetic circuit was tested for its ability to detect extracellular pH and to control the buildup of D-xylonic acid in the culture media. Results showed that the pH-responsive genetic sensor confers dynamic regulation of D-xylonic acid accumulation, which adjusts with the perturbation of culture media pH. This is the first report demonstrating the use of a pH-responsive transmembrane transcription factor as a transducer in a synthetic genetic circuit that was designed for XOP. This may serve as a benchmark for the development of other genetic controllers for similar pathways that involve acidic intermediates.

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Change history

  • 16 January 2020

    In the published version, the y-axis data of Fig. 3c was incorrectly inserted (OD600 instead of D-xylonate (g L<Superscript>-1</Superscript>) and the x-axes of Figs. 3b, 3d, 3e and 3f ended at 48 h instead of 72 h. See the correct Fig. 3 below.


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Correspondence to Won-Keun Lee or Wook-Jin Chung.

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Bañares, A.B., Valdehuesa, K.N.G., Ramos, K.R.M. et al. A pH-responsive genetic sensor for the dynamic regulation of D-xylonic acid accumulation in Escherichia coli. Appl Microbiol Biotechnol (2020).

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  • Xylose oxidative pathway
  • D-xylonic acid
  • Dahms pathway
  • CadC
  • Transcription factor
  • Biosensor