Five geranylgeranyl diphosphate synthases expressed in different organs are localized into three subcellular compartments in Arabidopsis
Five geranylgeranyl diphosphate synthases expressed in different organs are localized into three subcellular compartments in Arabidopsis
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DOI：
10.1104/pp.122.4.1045
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发表时间：
2000-04-01
期刊：
影响因子：
7.4
通讯作者：
Kamiya, Y
中科院分区：
文献类型：
--
作者：
Okada, K;Saito, T;Kamiya, Y
香叶基香叶基二磷酸（GGPP）是植物中赤霉素、类胡萝卜素、叶绿素、类异戊二烯醌和香叶基香叶基化蛋白质生物合成的前体。在拟南芥中存在一个GGPP酶基因小家族，编码5种同工酶和1种相关蛋白，所有同源物都有一个推定的定位信号，可以转位到特定的亚细胞区室中。使用合成的绿色荧光蛋白（sGFP），我们研究了这些GGPP酶的亚细胞定位。当这些融合蛋白由花椰菜花叶病毒35S启动子在拟南芥中表达时，GGPS1-sGFP和GGPS3-sGFP蛋白易位到叶绿体中，GGPS2-sGFP和GGPS4-sGFP蛋白定位在内质网中，而GGPS6-sGFP蛋白定位在线粒体中，将体外合成的GGPS1和GGPS3蛋白质都吸收到分离的完整豌豆叶绿体中并加工成成熟形式。RNA-blot和启动子-β-葡萄糖醛酸酶（GUS）分析表明，这些GGPP酶基因在拟南芥中的器官特异性表达。GGR和GGPS1广泛表达，而GGPS2、GGPS3和GGPS4分别在花、根和花中特异性表达。这些结果表明，每个GGPP合酶基因在植物发育过程中的不同组织中表达，GGPP是由细胞器本身合成，而不是被运输到细胞器。因此，我们预测在每个细胞器中GGPP的产生将有特定的途径。
Geranylgeranyl diphosphate (GGPP) is the precursor for the biosynthesis of gibberellins, carotenoids, chlorophylls, isoprenoid quinones, and geranylgeranylated proteins in plants. There is a small gene family for GGPP synthases encoding five isozymes and one related protein in Arabidopsis, and all homologs have a putative localization signal to translocate into specific subcellular compartments. Using a synthetic green fluorescent protein (sGFP), we studied the subcellular localization of these GGPP synthases. When these fusion proteins were expressed by the cauliflower mosaic virus 35S promoter in Arabidopsis, GGPS1-sGFP and GGPS3-sGFP proteins were translocated into the chloroplast, GGPS2-sGFP and GGPS4-sGFP proteins were localized in the endoplasmic reticulum, and the GGPS6-sGFP protein was localized in the mitochondria, Both GGPS1 and GGPS3 proteins synthesized in vitro were taken up into isolated intact pea chloroplasts and processed to the mature form. RNA-blot and promoter-beta-glucuronidase (GUS) analysis showed that these GGPP synthases genes are organ-specifically expressed in Arabidopsis. GGR and GGPS1 were ubiquitously expressed, while GGPS2, GGPS3, and GGPS4 were expressed specifically in the flower, root, and flower, respectively. These results suggest that each GGPP synthase gene is expressed in different tissues during plant development and GGPP is synthesized by the organelles themselves rather than being transported into the organelles. Therefore, we predict there will be specific pathways of GGPP production in each organelle.