Optogenetic switches for light-controlled gene expression in yeast

Abstract

Light is being increasingly recognized as an efficient and ideal controller of diverse biological processes: it provides high spatiotemporal resolution and it can be applied or removed with the click of a button. In addition, and importantly, it is a rather cheap resource; it is non-toxic and leaves no chemical traces in the media. Optogenetic switches are molecular devices that can process luminic information allowing light- controlled gene expression, protein localization, signal transduction and protein-protein interactions. Such molecular components in eukaryotic systems have been mainly developed through the use of plant and fungal photoreceptors, which upon light stimulation undergo conformational changes that allow modulating protein interactions (i.e homo or heterodimerization), which can be utilized to control signalling pathways or even transcription. The current repertoires of optogenetic switches include red, blue and UV-B light photoreceptors, and have been implemented in a broad spectrum of biological platforms. In this review, we have revisited different optogenetic switchesmplemented in diverse eukaryotic biological platforms with emphasis on those used for light-controlled gene expression in the budding yeast Saccharomyces cerevisiae. The implementation of these switches overcomes the use of traditional chemical inducers, allowing precise control of gene expression at lower costs positively impacting the production of high value metabolites and heterologous proteins. Additionally, we highlight the potential of utilizing this technology beyond laboratory strains, implementing it in yeasts tamed for industrial processes. Finally, we discuss how fungal photoreceptors could serve as a source of biological parts for the development of novel optogenetic switches with improved characteristics, increasing inducibility while reducing background expression in the dark. Although optogenetic tools have a strong impact on basic research, their use in applied sciences is still, somehow, undervalued. Therefore, the challenge to utilize this technology in biotechnological and industrial settings stands as an open invitation.