Abstract
Strictly controlled inducible gene expression is crucial when engineering biological systems where even tiny amounts of a protein have a large impact on function or host cell viability. In these cases, leaky protein production must be avoided at all costs. Here, we demonstrate how the central dogma offers a simple way to effectively address this challenge. By simultaneously regulating both transcriptional and translational levels, we show how basal expression of an inducible system can be reduced to virtually undetectable levels, with minimal impact on the maximum induced expression rate achieved. Using this approach, we create several stringent expression systems displaying >1000-fold change in their output after induction. Furthermore, we find that multi-level regulation is able to supress transcriptional noise and create a digital-like switch when transitioning between ‘on’ and ‘off’ states. This work provides foundational knowledge and a genetic toolkit of parts to create multi-level gene expression controllers for those working with toxic genes or requiring precise regulation and propagation of cellular signals. It also demonstrates the value of exploring more complex and diverse regulatory designs for synthetic biology.
Competing Interest Statement
The authors have declared no competing interest.