Mo Xu-Hua, Sun Yu-Man, Bi Yu-Xing, Zhao Yan, Yu Gui-Hong, Tan Ling-Ling, Yang Song
School of Life Sciences, Qingdao Agricultural University, 700 Changcheng Road, Qingdao, Shandong, 266109, China.
Shandong Province Key Laboratory of Applied Mycology, Qingdao Agricultural University, 700 Changcheng Road, Qingdao, Shandong, 266109, China.
Synth Syst Biotechnol. 2023 Aug 9;8(3):527-535. doi: 10.1016/j.synbio.2023.08.002. eCollection 2023 Sep.
species, the representative bacteria distributed in phyllosphere region of plants, often synthesize carotenoids to resist harmful UV radiations. is known to produce a carotenoid pigment and recent research revealed that this carotenoid has a C backbone. However, its exact structure remains unknown. In the present study, the carotenoid produced by AM1 was isolated and its structure was determined as 4-[2--11-octadecenoyl-β-glucopyranosyl]-4,4'-diapolycopenedioc acid (), a glycosylated C carotenoid. Furthermore, the genes related to the C carotenoid synthesis were investigated. Squalene, the precursor of the C carotenoid, is synthesized by the co-occurrence of META1p1815, META1p1816 and META1p1817. Further overexpression of the genes related to squalene synthesis improved the titer of carotenoid . By using gene deletion and gene complementation experiments, the glycosyltransferase META1p3663 and acyltransferase META1p3664 were firstly confirmed to catalyze the tailoring steps from 4,4'-diapolycopene-4,4'-dioic acid to carotenoid . In conclusion, the structure and biosynthetic genes of carotenoid produced by AM1 were firstly characterized in this work, which shed lights on engineering AM1 for producing carotenoid in high yield.
在植物叶际区域分布的代表性细菌物种通常合成类胡萝卜素以抵抗有害的紫外线辐射。已知某物种能产生一种类胡萝卜素色素，最近的研究表明这种类胡萝卜素具有C骨架。然而，其确切结构仍然未知。在本研究中，分离出了由AM1产生的类胡萝卜素，并确定其结构为4-[2--11-十八碳烯酰-β-吡喃葡萄糖基]-4,4'-二脱氢番茄红素二酸（），一种糖基化的C类胡萝卜素。此外，还研究了与C类胡萝卜素合成相关的基因。C类胡萝卜素的前体角鲨烯是由META1p1815、META1p1816和META1p1817共同作用合成的。进一步过表达与角鲨烯合成相关的基因提高了类胡萝卜素的产量。通过基因缺失和基因互补实验，首次证实糖基转移酶META1p3663和酰基转移酶META1p3664催化从4,4'-二脱氢番茄红素-4,4'-二酸到类胡萝卜素的修饰步骤。总之，本工作首次对AM1产生的类胡萝卜素的结构和生物合成基因进行了表征，这为通过工程改造AM1高产类胡萝卜素提供了思路。
