Enhancing erythromycin precursor 6-dEB production by using synthetic small regulatory RNAs in Escherichia coli

Abstract:

Although heterologous biosynthesis of polyketide erythromycin has been successfully achieved in Escherichia coli, the titer remains at a very low level (~10 mg/L). In this study, based on genome-scale metabolic model of E. coli, in silico method flux distribution comparison analysis was used to discover novel potential targets for heterologous 6-dEB biosynthesis. Synthetic small regulatory RNAs (sRNAs) was used to experimentally test 12 down-regulated targets. The results showed that repression of each of these target genes e.g. lsrC and ackA led to significantly improve heterologous 6-dEB biosynthesis. Using co-repression of lsrC and ackA, 6-dEB titer was improved by 59.9 % in shake-flask with a maximum yield of 22.8 mg/L. This study indicates that combined flux distribution comparison analysis and synthetic small regulatory RNAs is an effective strategy to improve 6-dEB production in E. coli.

Key words:Escherichia coli, 6-deoxyerythronolide B, heterologous biosynthesis, genome-scale metabolic model, synthetic small regulatory RNAs