Biological synthesis of coumarins in Escherichia coli.
BACKGROUND
Coumarins are a major group of plant secondary metabolites that serves as defense compounds against pathogens. Although coumarins can be obtained from diverse plant sources, the use of microorganisms to synthesize them could be an alternative way to supply building blocks for the synthesis of diverse coumarin derivatives.


RESULTS
Constructs harboring two genes, F6'H (encoding feruloyl CoA 6' hydroxylase) and 4CL (encoding 4-coumarate CoA:ligase), were manipulated to increase the productivity of coumarins. Escherichia coli expressing the two genes was cultured in medium supplemented with hydroxycinnamic acids (HCs) including p-coumaric acid, caffeic acid, and ferulic acid, resulting in the synthesis of the corresponding coumarins, umbelliferone, esculetin, and scopoletin. Cell concentration and initial substrate feeding concentration were optimized. In addition, umbelliferone, and esculetin were synthesized from glucose by using a ybgC deletion mutant and co-expressing tyrosine ammonia lyase and other genes involved in the tyrosine biosynthesis pathway.


CONCLUSIONS
To produce coumarin derivatives (umbelliferone, scopoletin, and esculetin) in E. coli, several constructs containing F6'H and 4CL were made, and their ability to synthesize coumarin derivatives was tested. The solubility of F6'H was critical for the final yield. After optimization, 82.9 mg/L of umbelliferone, 79.5 mg/L of scopoletin, and 52.3 mg/L of esculetin were biosynthesized from the corresponding HCs, respectively in E. coli. Umbelliferone and esculetin were also synthesized from glucose using engineered E. coli strains. The final yields of umbelliferone and esculetin were 66.1 and 61.4 mg/L, respectively.
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea. lcanldyl@nate.com.
So-Mi
SM
Yang
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea. kingyi92@naver.com.
Geun Young
GY
Shim
Department of Forest Resources, Gyeongnam National University of Science and Technology, 33 Dongjin-ro, Jinju-si, Gyeongsangman-do, Jinju, 660-758, Korea. dkimbk@gntech.ac.kr.
Bong-Gyu
BG
Kim
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea. jhahn@konkuk.ac.kr.
Joong-Hoon
JH
Ahn
D003373:Coumaric Acids / Q000378:metabolism*; D003374:Coumarins; D004926:Escherichia coli / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*
D003373:Coumaric Acids; D003374:Coumarins