Rapid and reversible regulation of cell cycle progression in budding yeast using optogenetics

The complexity of the eukaryotic cell cycle complicates experiment design and data interpretation, limiting our understanding of how cells coordinate cell cycle processes. Traditional perturbation methods, including knockouts, deletions, and arrest-inducing chemicals, are limited by compensatory feedback interactions or pleiotropic side effects. Inducible synthetic systems offer greater specificity but often rely on external inducers, making rapid reversibility difficult. Here, we developed OPTO-Cln2, an optogenetic tool for light-controlled and reversible regulation of G1 progression in budding yeast. Using time-lapse microscopy, we show that OPTO-Cln2-strains rapidly switch between normal and altered G1 progression. Combining OPTO-Cln2 with a readout of TORC1 and PKA activity, we find that oscillatory signaling dynamics is coordinated with G1 progression. Finally, we show that OPTO-Cln2 enables at least two cycles of synchronous arrest and release in liquid cultures. This system provides a powerful approach for studying cell cycle dynamics and the coordination of cell growth with division.