Crosstalk between cytosolic and plastidial pathways of isoprenoid biosynthesis in Arabidopsis thaliana
Crosstalk between cytosolic and plastidial pathways of isoprenoid biosynthesis in Arabidopsis thaliana
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DOI：
10.1073/pnas.1031755100
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发表时间：
2003-05-27
影响因子：
11.1
通讯作者：
Lange, BM
中科院分区：
文献类型：
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作者：
Laule, O;Fürholz, A;Lange, BM
在植物中，异戊烯基二磷酸和二甲基烯丙基二磷酸（类异戊二烯生物合成中的中心中间体）的形成是划分的：甲羟戊酸（MVA）途径，其定位于细胞质，负责甾醇、某些倍半萜和泛醌的侧链的合成;相反，最近发现的在质体中起作用的不依赖于MVA的途径涉及提供单萜、某些倍半萜、二萜、类胡萝卜素以及叶绿素和质体醌的侧链。MVA途径的特异性抑制剂（洛伐他汀）和MVA非依赖性途径（磷霉素）被用来干扰拟南芥幼苗的生物合成通量。两种途径之间的相互作用进行了研究，在转录水平上，通过使用基因芯片（Affytron）微阵列和在代谢物水平上，通过测定叶绿素，类胡萝卜素和甾醇。用洛伐他汀处理幼苗导致甾醇水平的瞬时降低和类胡萝卜素以及叶绿素水平的瞬时增加。在最初的下降之后，洛伐他汀处理的幼苗中的甾醇量恢复到高于对照的水平。作为对磷霉素处理的响应，观察到甾醇水平的瞬时增加，而叶绿素和类胡萝卜素的量与对照相比急剧下降。在96小时后，磷霉素添加，所有代谢产物（甾醇，叶绿素和类胡萝卜素）的水平测定大大低于对照组。有趣的是，这些代谢酶介导的变化并没有反映在参与固醇，叶绿素和类胡萝卜素代谢的基因的基因表达水平的改变。基因表达模式和类异戊二烯代谢产物的积累之间缺乏相关性表明转录后过程可能在调节类异戊二烯代谢途径的通量中发挥重要作用。
In plants, the formation of isopentenyl diphosphate and dimethylallyl diphosphate, the central intermediates in the biosynthesis of isoprenoids, is compartmentalized: the mevalonate (MVA) pathway, which is localized to the cytosol, is responsible for the synthesis of sterols, certain sesquiterpenes, and the side chain of ubiquinone; in contrast, the recently discovered MVA-independent pathway, which operates in plastids, is involved in providing the precursors for monoterpenes, certain sesquiterpenes, diterpenes, carotenoids, and the side chains of chlorophylls and plastoquinone. Specific inhibitors of the MVA pathway (lovastatin) and the MVA-independent pathway (fosmidomycin) were used to perturb biosynthetic flux in Arabidopsis thaliana seedlings. The interaction between both pathways was studied at the transcriptional level by using GeneChip (Affymetrix) microarrays and at the metabolite level by assaying chlorophylls, carotenoids, and sterols. Treatment of seedlings with lovastatin resulted in a transient decrease in sterol levels and a transient increase in carotenoid as well as chlorophyll levels. After the initial drop, sterol amounts in lovastatin-treated seedlings recovered to levels above controls. As a response to fosmidomycin treatment, a transient increase in sterol levels was observed, whereas chlorophyll and carotenoid amounts decreased dramatically when compared with controls. At 96 h after fosmidomycin addition, the levels of all metabolites assayed (sterols, chlorophylls, and carotenoids) were substantially lower than in controls. Interestingly, these inhibitor-mediated changes were not reflected in altered gene expression levels of the genes involved in sterol, chlorophyll, and carotenoid metabolism. The lack of correlation between gene expression patterns and the accumulation of isoprenoid metabolites indicates that posttranscriptional processes may play an important role in regulating flux through isoprenoid metabolic pathways.