Team:British Columbia/Biosensor

Biosensors are transcriptional systems that are responsive to the presence of a specific compound.1 These systems contain a transcription factor and a promoter sequence. The transcription factor interacts with the compound of interest, as well as an operator in the promoter sequence, in order to regulate expression of the gene under the control of that promoter.1 The presence of the compound of interest will either induce or repress the expression of a gene whose activity can be used as a metric of abundance of the compound.

When regulating the expression of a reporter gene, biosensors are becoming increasingly interesting tools in diagnostics and strain engineering.1, 2 However, biosensors can also be use as part of engineered regulatory systems, in which gene expression will be dependent on the presence or production of a specific metabolite.

FdeR, and associated promoter pfdeA, is a naringenin-responsive transcriptional regulator from Herbaspirillum seropedicae SmR1.3 In the absence of naringenin, FdeR remains unbound to the pfdeA operator.

When naringenin is present in the system, it binds to FdeR, inducing a conformational change that allows FdeR to bind to the pfdeA operator and induce expression at that locus.2, 3


  1. Cheng, F., X.-L. Tang, and T. Kardashliev, Transcription Factor-Based Biosensors in High-Throughput Screening: Advances and Applications. Biotechnology Journal, 2018. 13(7): p. 1700648.
  2. Raman, S., et al., Evolution-guided optimization of biosynthetic pathways. Proceedings of the National Academy of Sciences of the United States of America, 2014. 111(50): p. 17803-17808.
  3. Siedler, S., et al., Novel biosensors based on flavonoid-responsive transcriptional regulators introduced into Escherichia coli. Metabolic Engineering, 2014. 21: p. 2-8.