Optogenetic control for metabolic engineering using protein-level regulation

About This Grant

Microorganisms can be engineered to express proteins that direct the synthesis of valuable products. However, the resources used to accomplish this take away from resources devoted to maintaining normal cell functions, which can often result in reduced cell growth. This project will explore using light to control metabolic pathways with the goal of balancing production of valuable products and normal cell growth. The outcomes of this research could lead to advances in sustainable production by enabling light-controlled strategies for optimizing biosynthesis in real time. The research program is complemented by educational outreach. Most notable are efforts partnering with the STEM Pathways program to host an event at the Cambridge Science Festival. The project will also provide research training opportunities for undergraduate students. Designing and testing protein-level optogenetic regulation for metabolic engineering is promising and challenging. As a test case, the researchers will focus on octanoic acid, used in production of fuels, plastics, surfactants, and other products. Octanoic acid can be produced in Escherichia coli via expression of heterologous thioesterases. Production of octanoic acid is metabolically taxing, motivating the need for dynamic strategies to shift cellular resources between growth and production. First, the researchers will develop a novel method for generating light-inducible proteins. They will use a domain insertion approach to construct libraries of proteins containing a modular photodomain and will subject these libraries to selection to generate novel light-responsive thioesterases. Second, the project will comprehensively test light induction strategies to map the impact of temporal parameters associated with light exposure to production outcomes. This approach will provide insight into the differences between alternative optogenetic implementations and their ultimate impact on production. Third, the researchers will implement real-time feedback control to dynamically regulate growth and production. By implementing closed-loop control, the researchers will design autonomous methods for regulating bioproduction that are responsive to current conditions. The strategy is designed to capitalize on the unique benefits of reversibility and tunability that light affords to balance the trade-off between production and growth. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.