Optogenetic Control the Activity of Pyruvate Decarboxylase in <i>Saccharomyces cerevisiae</i> for Tunable Ethanol Production

<i>Saccharomyces cerevisiae</i> is a widely used chassis in metabolic engineering. Due to the Crabtree effect, it preferentially produces ethanol under high-glucose conditions, limiting the synthesis of other valuable metabolites. Conventional metabolic engineering approaches typically rely on irreversible genetic modifications, making it insufficient for dynamic metabolic control. In contrast, optogenetics offers a reversible and tunable method for regulating cellular metabolism with high temporal precision. In this study, we engineered the pyruvate decarboxylase isozyme 1 (Pdc1) by inserting the photosensory modules (AsLOV2 and cpLOV2 domains) into rationally selected positions within the enzyme. Through a growth phenotype-based screening system, we identified two blue light-responsive variants, OptoPdc1^D1 and OptoPdc1^D2, which enable light-dependent control of enzymatic activity. Leveraging these OptoPdc1 variants, we developed opto-<i>S. cerevisiae</i> strains, MLy-9 and MLy-10, which demonstrated high efficiency in modulating both cell growth and ethanol production. These strains allow reliable regulation of ethanol biosynthesis in response to blue light, achieving a dynamic control range of approximately 20- to 120-fold. The opto-<i>S. cerevisiae</i> strains exhibited dose-dependent production in response to blue light intensity and pulse patterns, confirming their potential for precise metabolic control. This work establishes a novel protein-level strategy for regulating metabolic pathways in <i>S. cerevisiae</i> and introduces an effective method for controlling ethanol metabolism via optogenetic regulation.