The Inducible Q System Enables Simultaneous Optogenetic Amplification and Inversion in for Bidirectional Control of Gene Expression. Author Makoto Lalwani, Evan Zhao, Scott Wegner, José Avalos Publication Year 2021 Type Journal Article Abstract Bidirectional optogenetic control of yeast gene expression has great potential for biotechnological applications. Our group has developed optogenetic inverter circuits that activate transcription using darkness, as well as amplifier circuits that reach high expression levels under limited light. However, because both types of circuits harness Gal4p and Gal80p from the galactose (GAL) regulon they cannot be used simultaneously. Here, we apply the Q System, a transcriptional activator/inhibitor system from , to build circuits in that are inducible using quinic acid, darkness, or blue light. We develop light-repressed OptoQ-INVRT circuits that initiate darkness-triggered transcription within an hour of induction, as well as light-activated OptoQ-AMP circuits that achieve up to 39-fold induction. The Q System does not exhibit crosstalk with the GAL regulon, allowing coutilization of OptoQ-AMP circuits with previously developed OptoINVRT circuits. As a demonstration of practical applications in metabolic engineering, we show how simultaneous use of these circuits can be used to dynamically control both growth and production to improve acetoin production, as well as enable light-tunable co-production of geraniol and linalool, two terpenoids implicated in the hoppy flavor of beer. OptoQ-AMP and OptoQ-INVRT circuits enable simultaneous optogenetic signal amplification and inversion, providing powerful additions to the yeast optogenetic toolkit. Keywords Trans-Activators, Saccharomyces cerevisiae, Optogenetics, Gene Expression Regulation, Fungal, Fungal Proteins, Metabolic Engineering, Neurospora crassa Journal ACS Synth Biol Volume 10 Issue 8 Pages 2060-2075 Date Published 2021 Aug 20 ISSN Number 2161-5063 DOI 10.1021/acssynbio.1c00229 Alternate Journal ACS Synth Biol PMID 34346207 PubMedGoogle ScholarBibTeXEndNote X3 XML