Regulating malonyl-CoA metabolism via synthetic antisense RNAs for enhanced biosynthesis of natural products

Malonyl-CoA is the building block for fatty acid biosynthesis and also a precursor to various pharmaceutically and industrially valuable molecules, such as polyketides and biopolymers. However, intracellular malonyl-CoA is usually maintained at low levels, which poses great challenges to efficient microbial production of malonyl-CoA derived molecules. Inactivation of the malonyl-CoA consumption pathway to increase its intracellular availability is not applicable, since it is usually lethal to microorganisms. In this work, we employ synthetic antisense RNAs (asRNAs) to conditionally down-regulate fatty acid biosynthesis and achieve malonyl-CoA enrichment in Escherichia coil. The optimized asRNA constructs with a loop-stem structure exhibit high interference efficiency up to 80%. leading to a 45-fold increase in intracellular malonyl-CoA concentration when fabD gene expression is inhibited. Strikingly, this strategy allows the improved production of natural products 4-hyclroxycoumarin, resveratrol, and naringenin by 2.53-, 1.70-, and 1.53-fold in E. colt, respectively. In addition, down-regulation of other jab genes including fabl 1, fabB, and fabF also leads to remarkable increases in 4-hydroxycoumarin production. This study demonstrates a novel strategy to enhance intracellular malonyl-CoA and indicates the effectiveness of asRNA as a powerful tool for use in metabolic engineering. (C) 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.