BioFuse: A programmable timer switch of gene expression.

Current gene circuits designed to time gene expression depend on the intricate interactions among various regulators and their targets, which confines them to a limited range of temporal tunability. Here, we report a programmable timer switch of gene expression termed BioFuse, which allows the reaction time ranging from hours to days. BioFuse comprises a series of fuse-like tandem DNA cassettes that can be sequentially edited by the adenine base editors (ABEs), resulting in either the activation or deactivation of a downstream gene once the editing is complete. Adjusting the number of DNA cassettes incorporated allows precise programming of BioFuse's reaction time. Applying BioFuse to control carotenoid biosynthesis genes decouples lycopene production from growth in E. coli and increases lycopene yield without external inducers. Using BioFuse in a bacterial autolysis system enables timely and efficient protein release. BioFuse offers a versatile tool for precise, wide-range timing of gene expression and metabolic activities in bacteria, with potential applications in industry and biomedicine.