title: Metabolic engineering of Escherichia coli to produce zeaxanthin.
abstract: Zeaxanthin is a high-value carotenoid that is used in nutraceuticals, cosmetics, food, and animal feed industries. Zeaxanthin is chemically synthesized or purified from microorganisms as a natural product; however, increasing demand requires development of alternative sources such as heterologous biosynthesis by recombinant bacteria. For this purpose, we molecularly engineered Escherichia coli to optimize the synthesis of zeaxanthin from lycopene using fusion protein-mediated substrate channeling as well as by the introduction of tunable intergenic regions. The tunable intergenic regions approach was more efficient compared with protein fusion for coordinating expression of lycopene β-cyclase gene crtY and β-carotene 3-hydroxylase gene crtZ. The influence of the substrate channeling effect suggests that the reaction catalyzed by CrtZ is the rate-limiting step in zeaxanthin biosynthesis. Then Pantoea ananatis, Pantoea agglomerans and Haematococcus pluvialis crtZ were compared. Because P. ananatis crtZ is superior to that of P. agglomerans or H. pluvialis for zeaxanthin production, we used it to generate a recombinant strain of E. coli BETA-1 containing pZSPBA-2(P37-crtZPAN) that produced higher amounts of zeaxanthin (11.95 ± 0.21 mg/g dry cell weight) than other engineered E. coli strains described in the literature.
authors.affiliation: Biotechnology Research Center and Biomedical Center, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, People's Republic of China.
authors.forename: Xi-Ran
authors.initials: XR
authors.lastname: Li
authors.forename: Gui-Qiao
authors.initials: GQ
authors.lastname: Tian
authors.forename: Hong-Jie
authors.initials: HJ
authors.lastname: Shen
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Liu
mesh_terms: D002338:Carotenoids / Q000378:metabolism; D000460:Chlorophyta / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism; D000077276:Lycopene; D060847:Metabolic Engineering; D006899:Mixed Function Oxygenases / Q000378:metabolism; D020636:Pantoea / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D065146:Zeaxanthins / Q000096:biosynthesis*; D019207:beta Carotene / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D065146:Zeaxanthins; D019207:beta Carotene; D002338:Carotenoids; D006899:Mixed Function Oxygenases; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase; D000077276:Lycopene