Optogenetics switches: tunable tools to control gene expression and biotechnologically relevant phenotypes in Saccharomyces cerevisiae

The fungus Neurospora crassa strongly responds to blue-light through a transcriptional heterocomplex that includes WC-1. The latter possesses a LOV (Light-Oxygen-Voltage) domain capable of detecting blue light, which promotes a conformational change that leads to a light-dependent dimerization that results in strong transcriptional activation. Thus, the expression of WC-1-target genes is rapidly and precisely controlled in a dose-dependent manner when light is present. In order to design and improve optogenetic switches that can be utilized in other organisms as orthogonal controllers, we have been exploring the dynamics of light responses in this organism. Through the development of simple synthetic switches we have successfully implemented a blue-light responding transcriptional system in Saccharomyces cerevisiae. Therefore, now in yeast (which naturally does not respond to light) we can efficiently and orthogonally induce gene expression by adding such an optogenetic switch. The latter yields a broad dynamic range of expression, as evidenced by a luciferase reporter. In addition, this system works as good as (and even better) that available commercial yeast inducible kits, such as GAL4. Moreover, we have assembled this optogenetic switch as part of a simple genetic circuit in order to control a relevant biotechnological process, such as flocculation. Therefore, we can control the occurrence of flocculation by the presence of an external cue: light. Depending on how the circuit is assembled, we can trigger flocculation by the absence or presence of such stimulus. Thus, such an optogenetic switch in yeast provides a versatile toolbox for biotechnological applications. Funding MN-FISB120043, FONDECYT 1130822