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Real time control of gene expression in yeast
Gene expression plays a central role in the orchestration of cellular processes. The use of inducible promoters to change the level of expression of a gene from its physiological level has significantly contributed to understanding the functioning of many regulatory networks. Here, we show that by implementing an external, in silico, feedback loop, one can tightly control the expression of a gene in real time over many cell generations. We developed a platform for real-time, closed-loop control of gene expression that integrates microscopy for monitoring gene expression in yeast cells, microfluidics to manipulate the cells environment, and a dedicated software for automated imaging, quantification and model predictive control strategy. We used an endogenous osmo-stress responsive promoter and played with the osmolarity of the cells environment, to demonstrate that long-term control can indeed be achieved for both time-constant and time-varying target profiles, at the population level, and even at the single-cell level. I’ll present this method and discuss the dynamical properties of the HOG cascade that drives the reponse of yeast cells to osmotic stress. I’ll then briefly discuss how this approach could be used to probe quantitatively the dynamical properties of cellular processes and drive the functioning of synthetic networks in live cells.