Triterpene Functional Genomics in Licorice for Identification of CYP72A154 Involved in the Biosynthesis of Glycyrrhizin
Triterpene Functional Genomics in Licorice for Identification of CYP72A154 Involved in the Biosynthesis of Glycyrrhizin
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DOI：
10.1105/tpc.110.082685
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发表时间：
2011-11-01
期刊：
影响因子：
11.6
通讯作者：
Muranaka, Toshiya
中科院分区：
文献类型：
--
作者：
Seki, Hikaru;Sawai, Satoru;Muranaka, Toshiya
甘草酸是一种从甘草属植物（甘草）地下部分提取的三萜皂苷，具有多种药理活性，在世界各地也被用作天然甜味剂。甘草酸的生物合成包括2,3-氧化角鲨烯初始环化为三萜骨架β -amyrin，随后在C-11和C-30位置发生一系列氧化反应，糖基转移到C-3羟基。我们之前报道了细胞色素P450单加氧酶（P450）基因编码β -amyrin 11-氧化酶（CYP88D6）作为甘草酸生物合成的初始P450基因的鉴定。在这项研究中，第二个相关的P450 （CYP72A154）被确定并证明在甘草酸途径中负责C-30氧化。CYP72A154在一种工程酵母菌中表达，该酵母菌内源性产生11-氧- β -amyrin（可能是β -amyrin和甘草酸之间的生物合成中间体），催化原位供应的11-氧- β -amyrin在C-30的三个连续氧化步骤产生甘草酸苷元。此外，与CYP72A154序列相似性较高的Medicago truncatula CYP72A63能够催化β -amyrin的C-30氧化。这些结果揭示了CYP72A亚家族蛋白作为三萜氧化酶的功能，并为甘草酸的工程生产提供了遗传工具。
Glycyrrhizin, a triterpenoid saponin derived from the underground parts of Glycyrrhiza plants (licorice), has several pharmacological activities and is also used worldwide as a natural sweetener. The biosynthesis of glycyrrhizin involves the initial cyclization of 2,3-oxidosqualene to the triterpene skeleton beta-amyrin, followed by a series of oxidative reactions at positions C-11 and C-30, and glycosyl transfers to the C-3 hydroxyl group. We previously reported the identification of a cytochrome P450 monooxygenase (P450) gene encoding beta-amyrin 11-oxidase (CYP88D6) as the initial P450 gene in glycyrrhizin biosynthesis. In this study, a second relevant P450 (CYP72A154) was identified and shown to be responsible for C-30 oxidation in the glycyrrhizin pathway. CYP72A154 expressed in an engineered yeast strain that endogenously produces 11-oxo-beta-amyrin (a possible biosynthetic intermediate between beta-amyrin and glycyrrhizin) catalyzed three sequential oxidation steps at C-30 of 11-oxo-beta-amyrin supplied in situ to produce glycyrrhetinic acid, a glycyrrhizin aglycone. Furthermore, CYP72A63 of Medicago truncatula, which has high sequence similarity to CYP72A154, was able to catalyze C-30 oxidation of beta-amyrin. These results reveal a function of CYP72A subfamily proteins as triterpene-oxidizing enzymes and provide a genetic tool for engineering the production of glycyrrhizin.