Transcription Factor-Based Biosensors in High-Throughput Screening: Advances and Applications

The molecular mechanisms that cells use to sense changes in the intra- and extracellular environment are increasingly utilized in synthetic biology to build genetic reporter constructs for various applications. Although in nature sensing can be RNA-mediated, most existing genetically-encoded biosensors are based on transcription factors (TF) and cognate DNA sequences. Here, the recent advances in the integration of TF-based biosensors in metabolic and protein engineering screens whereas distinction is made between production-driven and competitive screening systems for enzyme evolution under physiological conditions are discussed. Furthermore, the advantages and disadvantages of existing TF-based biosensors are examined with respects to dynamic range, sensitivity, and robustness, and compared to other screening approaches. The application examples discussed in this review demonstrate the promising potential TF-based biosensors hold as screening tools in laboratory evolution of proteins and metabolic pathways, alike.