Design of a Transcriptional Biosensor for the Portable, On-Demand Detection of Cyanuric Acid

ACS Synth Biol. 2020 Jan 17;9(1):84-94. doi: 10.1021/acssynbio.9b00348. Epub 2019 Dec 26.


Rapid molecular biosensing is an emerging application area for synthetic biology. Here, we engineer a portable biosensor for cyanuric acid (CYA), an analyte of interest for human and environmental health, using a LysR-type transcription regulator (LTTR) from Pseudomonas within the context of Escherichia coli gene expression machinery. To overcome cross-host portability challenges of LTTRs, we rationally engineered hybrid Pseudomonas-E. coli promoters by integrating DNA elements required for transcriptional activity and ligand-dependent regulation from both hosts, which enabled E. coli to function as a whole-cell biosensor for CYA. To alleviate challenges of whole-cell biosensing, we adapted these promoter designs to function within a freeze-dried E. coli cell-free system to sense CYA. This portable, on-demand system robustly detects CYA within an hour from laboratory and real-world samples and works with both fluorescent and colorimetric reporters. This work elucidates general principles to facilitate the engineering of a wider array of LTTR-based environmental sensors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / metabolism
  • Biosensing Techniques / methods*
  • Cell-Free System
  • Chimera / genetics
  • Escherichia coli / genetics*
  • Gene Expression
  • Gene Expression Regulation, Bacterial
  • Ligands
  • Plasmids / genetics
  • Promoter Regions, Genetic
  • Pseudomonas / genetics*
  • Synthetic Biology / methods
  • Transcription Factors / metabolism
  • Transcription, Genetic*
  • Triazines / analysis*


  • Bacterial Proteins
  • Ligands
  • Transcription Factors
  • Triazines
  • LysR protein, Bacteria
  • cyanuric acid