Chapter 8: Customizing Transcription-factor Biosensors for Modern Biotechnology

The biosynthesis of chemicals by engineered microbial strains that harbour natural and engineered variants of enzymes and biosynthetic pathways has been leveraged for the renewable, scalable, and efficient production of compounds from inexpensive chemical feedstocks. Advances in the microbial production of chemicals rely heavily on the rapidly developing fields of enzyme engineering, metabolic engineering, and synthetic biology, coupled with the decreasing cost of DNA synthesis and next-generation sequencing, along with the improved precision and versatility of laboratory automation. In order to overcome our limited ability to rationally redesign and/or improve the efficiency of engineered microbial strains, high-throughput screening or selection of vast libraries of enzyme and/or pathway variants is carried out. Genetically-encoded biosensors based on transcription factors offer a potentially versatile and modular platform technology to enable high-throughput screens and selections. Often though, a transcription factor-based biosensor with the desired target chemical specificity or operational characteristics is not available. To address this limitation, a variety of approaches are being developed to fine-tune the function and properties of transcription factors and to create custom biosensors for a variety of applications. This chapter will highlight these efforts and offer a perspective on the current and future state of the art.