Coordinating caffeic acid and salvianic acid A pathways for efficient production of rosmarinic acid in Escherichia coli

• Published in: Metabolic engineering 2023-03, Vol.76, p.29-38
• Main Authors: Wang, Lian, Wang, Huijing, Chen, Jianbin, Qin, Zhijie, Yu, Shiqin, Zhou, Jingwen
• Format: Article
• Language: English
• Subjects: Biosynthetic Pathways; Cofactor; Escherichia coli; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; L-amino acid Deaminase; Metabolic Engineering; Rosmarinic Acid; Thioesterase
• ISSN: 1096-7176; 1096-7184
• DOI: 10.1016/j.ymben.2023.01.002

Rosmarinic acid is a natural hydroxycinnamic acid ester used widely in the food and pharmaceutical industries. Although many attempts have been made to screen rate-limiting enzymes and optimize modules through co-culture fermentation, the titer of rosmarinic acid remains at the microgram level by microorganisms. A de novo biosynthetic pathway for rosmarinic acid was constructed based on caffeic acid synthesis modules in Escherichia coli. Knockout of competing pathways increased the titer of rosmarinic acid and reduced the synthesis of rosmarinic acid analogues. An L-amino acid deaminase was introduced to balance metabolic flux between the synthesis of caffeic acid and salvianic acid A. The ratio of FADH2/FAD was maintained via the coordination of deaminase and HpaBC, which is responsible for caffeic acid synthesis. Knockout of menI, encoding an endogenous thioesterase, increased the stability of caffeoyl-CoA. The final strain produced 5780.6 mg/L rosmarinic acid in fed-batch fermentation, the highest yet reported for microbial production. The strategies applied in this study lay a foundation for the synthesis of other caffeic acid and rosmarinic acid derivatives. •Knockout of competing pathways for L-tyrosine synthesis reduces analogues of RA.•Heterologous expression of TcTAL significantly reduces the accumulation of intermediates L-DOPA.•LAAD balances the flux to two modules and maintains the ratio of FADH2/FAD with HpaB.•Knockout of menI promotes the conversion efficiency of caffeic acid to RA.•The highest titer of RA reached 5780.9 mg/L in a 5 L fermenter.