Synthetic Transcription Regulation System for Orthogonal Control of Gene Expression

This work describes the development and experimental as well as mathematical characterization of a modular synthetic expression system that has compact bidirectional architecture and enables a broad range of adjustable and predictable expression outputs in S. cerevisiae. In the system, the input signal is transferred via a synthetic transcription factor (sTF) into a synthetic promoter and a defined core promoter to generate an output signal. The system activation is based on a set of bacterial DNA-binding domains, modular binding sites in the DNA and a selection of transcription activation domains. The system tuning is achieved through selection of three separate modules, each of which enables an adjustable output signal regulation: 1) the transcription-activation domain of the sTF, 2) the binding-site modules in the output promoter, and 3) the core promoter modules which define the transcription initiation site in the output promoter. The system contains also a collection of repressor modules that together with the activation modules enable diverse control of gene expression. In contrast to most existing modular gene expression regulation systems, the present system is independent from externally added compounds. Furthermore, the system provides robust functionality that is minimally affected by growth conditions. These features should make it useful also in large scale biotechnology applications. Recent results on the expansion of the catalogue of the various parts for more complex cellular control and description of the system’s functionality beyond S. cerevisiae will be described.