Cellular and subcellular localization of flavin-monooxygenases involved in glucosinolate biosynthesis
Cellular and subcellular localization of flavin-monooxygenases involved in glucosinolate biosynthesis
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DOI：
10.1093/jxb/erq369
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发表时间：
2011-01-01
影响因子：
6.9
通讯作者：
Halkier, Barbara A.
中科院分区：
文献类型：
--
作者：
Li, Jing;Kristiansen, Kim A.;Halkier, Barbara A.
硫代葡萄糖苷是由氨基酸衍生的次生代谢产物，其多样的生物活性取决于侧链的化学修饰。最近在拟南芥中鉴定出五种黄素单加氧酶FMOGS - OX1 - 5为脂肪族硫代葡萄糖苷侧链修饰酶，它们催化生成甲基亚磺酰烷基硫代葡萄糖苷，后者可水解为对人类健康和植物防御具有独特益处的产物。尽管大多数脂肪族硫代葡萄糖苷生物合成酶的定位已确定，但尽管侧链修饰很重要，其发生位置却鲜为人知。因此，通过表达由FMOGS - OX1 - 5启动子控制的绿色荧光蛋白（GFP）和β - 葡萄糖醛酸酶（GUS）融合基因，研究了拟南芥中FMOGS - OX1 - 5基因的空间表达模式。还通过在烟草叶片中瞬时表达FMOGS - OX1 - 黄色荧光蛋白（YFP）融合蛋白检测了FMOGS - OX1的细胞区室化。结果表明，FMOGS - OX1 - 5基本上在维管组织中表达，特别是在韧皮部细胞中，与其他硫代葡萄糖苷生物合成基因一样。它们也在花茎的内皮层样细胞和叶片的表皮细胞中被发现，这是其他硫代葡萄糖苷生物合成基因未曾报道过的位置。这表明FMOGS - OX1 - 5的空间表达模式决定了酶对其底物的可及性，从而影响硫代葡萄糖苷的分布。FMOGS - OX1 - YFP融合蛋白分析确定FMOGS - OX1为一种胞质蛋白。结合其他生物合成酶的亚细胞定位，讨论了多区室化的脂肪族硫代葡萄糖苷生物合成途径的综合图谱。
Glucosinolates are amino acid-derived secondary metabolites with diverse biological activities dependent on chemical modifications of the side chain. Five flavin-monooxygenases FMOGS-OX1-5 have recently been identified as aliphatic glucosinolate side chain modification enzymes in Arabidopsis thaliana that catalyse the generation of methylsulphinylalkyl glucosinolates, which can be hydrolysed to products with distinctive benefits for human health and plant defence. Though the localization of most aliphatic glucosinolate biosynthetic enzymes has been determined, little is known about where the side chain modifications take place despite their importance. Hence, the spatial expression pattern of FMOGS-OX1-5 genes in Arabidopsis was investigated by expressing green fluorescent protein (GFP) and beta-glucuronidase (GUS) fusion genes controlled by FMOGS-OX1-5 promoters. The cellular compartmentation of FMOGS-OX1 was also detected by transiently expressing a FMOGS-OX1-yellow fluorescent protein (YFP) fusion protein in tobacco leaves. The results showed that FMOGS-OX1-5 were expressed basically in vascular tissues, especially in phloem cells, like other glucosinolate biosynthetic genes. They were also found in endodermis-like cells in flower stalk and epidermal cells in leaf, which is a location that has not been reported for other glucosinolate biosynthetic genes. It is suggested that the spatial expression pattern of FMOGS-OX1-5 determines the access of enzymes to their substrate and therefore affects the glucosinolate profile. FMOGS-OX1-YFP fusion protein analysis identified FMOGS-OX1 as a cytosolic protein. Together with the subcellular locations of the other biosynthetic enzymes, an integrated map of the multicompartmentalized aliphatic glucosinolate biosynthetic pathway is discussed.