Development of a Genetically Encoded Biosensor for Detection of Polyketide Synthase Extender Units in Escherichia coli

The scaffolds of polyketidesare constructed via assembly of extender units based on malonyl-CoAand its derivatives that are substituted at the C2-position with diverse chemical functionality. Subsequently, a transcription- factor-based biosensorfor malonyl-CoAhas proven to be a powerful tool for detecting malonyl-CoA, facilitating the dynamic regulation of malonyl-CoA biosynthesisand guiding high-throughput engineering of malonyl-CoA-dependent processes. Yet, a biosensorfor the detection of malonyl-CoAderivatives has yet to be reported, severely restricting the application of high-throughput synthetic biologyapproaches to engineering extender unit biosynthesisand limiting the ability to dynamically regulate the biosynthesisof polyketideproducts that are dependent on such α-carboxyacyl-CoAs. Herein, the FapR biosensorwas re-engineered and optimized for a range of mCoA concentrations across a panel of E. coli strains. The effector specificity of FapR was probed by cell-free transcription–translat...