Genomics-based selection and functional characterization of triterpene glycosyltransferases from the model legume Medicago truncatula
Genomics-based selection and functional characterization of triterpene glycosyltransferases from the model legume Medicago truncatula
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DOI：
10.1111/j.1365-313x.2005.02344.x
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发表时间：
2005-03-01
期刊：
影响因子：
7.2
通讯作者：
Dixon, RA
中科院分区：
文献类型：
--
作者：
Achnine, L;Huhman, DV;Dixon, RA
尽管三萜皂苷的糖基化次级代谢产物对植物防御和动物健康很重要，但其生物合成的特征很差。模式豆科植物蒺藜苜蓿（Medicago truncatula）基于至少五种三萜苷元合成超过30种不同的皂苷;大豆皂苷元醇B和E、medicagenic acid、常春藤皂苷元和bayogenin。我们采用了诱导型细胞培养系统，DNA阵列为基础的和在电脑转录谱，并有针对性的代谢产物谱，以确定三萜糖基转移酶（GT）中的300多个GT中表达的M。蒺藜对两种尿苷二磷酸葡萄糖基转移酶进行了功能表征; UGT 73 K1对常春藤皂苷元和大豆皂草醇B和E具有特异性，UGT 71 G1对苜蓿酸具有特异性。后一种酶还以比三萜更高的效率糖基化某些异黄酮和黄酮醇槲皮素;然而，综合转录物和代谢物分析支持UGT 71 G1在萜类化合物生物合成中的功能，但在诱导的细胞培养物中不支持（异）黄酮生物合成。
The biosynthesis of triterpene saponins is poorly characterized in spite of the importance of these glycosylated secondary metabolites for plant defense and animal health. The model legume Medicago truncatula synthesizes more than 30 different saponins based on at least five triterpene aglycones; soyasapogenols B and E, medicagenic acid, hederagenin and bayogenin. We have employed an inducible cell culture system, DNA array-based and in silico transcript profiling, and targeted metabolite profiling, to identify triterpene glycosyltransferases (GTs) from among the more than 300 GTs expressed in M. truncatula. Two uridine diphosphate glucosyltransferases were functionally characterized; UGT73K1 with specificity for hederagenin and soyasapogenols B and E, and UGT71G1 with specificity for medicagenic acid. The latter enzyme also glycosylated certain isoflavones and the flavonol quercetin with higher efficiency than triterpenes; however, integrated transcript and metabolite profiling supported a function for UGT71G1 in terpenoid but not (iso) flavonoid biosynthesis in the elicited cell cultures.