(213g) Overproduction Of Ohhl In E. Coli Via Directed Evolution And Metabolic Engineering

Bacterial quorum sensing has been extensively used to construct artificial genetic circuits to implement complicated dynamic outputs, especially when population-synchronized outputs are involved. To further extend the applications of quorum sensing in synthetic biology, a set of engineered quorum-sensing systems with a wide range of functionalities are desired, such as these with minimal cross-talks or responding at different cell densities. To achieve these functions, metabolically engineered E. coli that can produce 3-oxo-hexanyl homoserine lactone (OHHL) at a certain rate is frequently a key component. We will present our recent work on the overproduction of OHHL via directed evolution and metabolic engineering. Specifically, we have used directed evolution to enhance the production yield of LuxI, the enzyme which synthesizes OHHL. A substrate of LuxI, acyl-ACP, is a key component of the bacterial de novo fatty acid biosynthesis pathway. To further increase the yield, we engineered this pathway to overproduce acyl-ACP. Quantitative analysis of OHHL indicates that the metabolically engineered E. coli produces OHHL in a significantly increased yield. Taken together, we have obtained a metabolically engineered E. coli strain that can be used to construct engineered quorum-sensing systems with promising applications in synthetic biology.