Fine-tuning of the fatty acid pathway by synthetic antisense RNA for enhanced (2S)-naringenin production from L-tyrosine in Escherichia coli.

Malonyl coenzyme A (malonyl-CoA) is an important precursor for the synthesis of natural products, such as polyketides and flavonoids. The majority of this cofactor is often consumed for producing fatty acids and phospholipids, leaving only a small amount of cellular malonyl-CoA available for producing the target compound. Tuning of malonyl-CoA into heterologous pathways yields significant phenotypic effects, such as growth retardation and even cell death. In this study, fine-tuning of the fatty acid pathway in Escherichia coli with antisense RNA (asRNA) to balance the demands on malonyl-CoA for target-product synthesis and cell health was proposed. To establish an efficient asRNA system, the relationship between sequence and function for asRNA was explored. It was demonstrated that the gene-silencing effect of asRNA could be tuned by directing asRNA to different positions in the 5'-UTR (untranslated region) of the target gene. Based on this principle, the activity of asRNA was quantitatively tailored to balance the need for malonyl-CoA in cell growth and the production of the main flavonoid precursor, (2S)-naringenin. Appropriate inhibitory efficiency of the anti-fabB/fabF asRNA improved the production titer by 431% (391 mg/L). Therefore, the strategy presented in this study provided a useful tool for the fine-tuning of endogenous gene expression in bacteria.Copyright 2014, American Society for Microbiology. All Rights Reserved.