Allosteric Regulation of DNA Circuits Enables Minimal and Rapid Biosensors of Small Molecules

Detection of environmental pollutants is crucial to safeguard ecological and public health. Here, we report a modular biosensing approach for the detection of contaminants based on the regulation of a minimal DNA signal amplifier and transducer circuit by allosteric transcription factors and their cognate ligands. We leverage the competition between allosteric proteins and an endonuclease to modulate cascade toehold-mediated strand displacement reactions, which are triggered in the presence of specific effectors and sustained by the endonuclease. We built two optical biosensors for the detection of tetracyclines and macrolides in water using repressors TetR and MphR, respectively. We demonstrate that our minimal, fast, and single-step biosensors can successfully detect antibiotics in nanomolar levels and apply them to report the presence of spiked-in antibiotics in water samples in a matter of minutes, suggesting great potential for monitoring of water contaminants.

Automated summary

The study introduces a new modular biosensing approach for detecting environmental pollutants, utilizing DNA signal amplifiers and transducer circuits controlled by allosteric transcription factors and their ligands. By leveraging competition between allosteric proteins and endonucleases, the researchers successfully built optical biosensors for detecting tetracyclines and macrolides in water. The minimal, fast, and single-step biosensors were shown to detect antibiotics in nanomolar levels and have great potential for monitoring water contaminants.