A modular toolset for electrogenetics

Synthetic biology research and its industrial applications rely on the deterministic spatiotemporal control of gene expression. Recently, electrochemical control of gene expression has been demonstrated in electrogenetic systems (redox-responsive promoters used alongside redox inducers and an electrode), allowing for the direct integration of electronics with complex biological processes for a variety of new applications. However, the use of electrogenetic systems is limited by poor activity, tunability and standardisation. Here, we have developed a variety of genetic and electrochemical tools that facilitate the design and vastly improve the performance of electrogenetic systems. We developed a strong, unidirectional, redox-responsive promoter before deriving a mutant promoter library with a spectrum of strengths. We then constructed genetic circuits with these parts and demonstrated their activation by multiple classes of redox molecules. Finally, we demonstrated electrochemical activation of gene expression in aerobic conditions utilising a novel, modular bioelectrochemical device. This toolset provides researchers with all the elements needed to design and build optimised electrogenetic systems for specific applications.