Accessing Electronic Control of Microbial Gene Expression with Multiplexed Electronic Signals

Abstract

Redox reactions provide a unique vantage point to bridge the disparate communication modalities of biological signal transduction and electronics. Electronic communication is rapid, well-studied, and easily user-operated, while also enabling integration with broader electronic networks. Biological signal transduction systems and synthetic biology offer valuable capabilities of sensing the physical and chemical environment, processing information, and altering gene expression output. In this dissertation, we discuss the role of redox in cellular growth and metabolism and describe its effectiveness as an engineering target to improve bioproduction. We posit that integrating electronics with biology provides orthogonal, selective, and information-rich opportunities for programmable actuation and quantitative sensing of biomolecular communication. Redox-mediated electronic control of gene expression, or electrogenetics, is an emerging technique that has already revealed novel capabilities, such as real-time communication and feedback control, but has a limited set of synthetic biology tools. This work introduces a new mechanism and electronic potential range for tunable electrogenetic control. We show that the phenolic molecule acetosyringone acts as a pro-signal, inducing OxyR-mediated electrogenetic expression specifically at oxidizing potentials. With this discovery, we create an electronic band-stop filter where electronically sliding the applied potential to either oxidative or reductive extremes induces the same regulon but through distinct mechanisms. Next, we develop a new electrogenetic MarR-regulated promoter. With this addition to the electrogenetics toolbox, we demonstrate the selectivity and multiplexity of signaling when multiple electrogenetic cells are employed simultaneously. Finally, we show that electrogenetics make possible the transduction of information from biological to electronic formats. Expanding the toolbox of electrogenetic parts will lay the foundation for building more intricate electrogenetic circuits, conducting bidirectional flow of information between biological activity and electronics, and interfacing biology with electronic devices and broader networks.