Estévez J M, Cantero A, Reindl A, Reichler S, León P
Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México.
J Biol Chem. 2001 Jun 22;276(25):22901-9. doi: 10.1074/jbc.M100854200. Epub 2001 Mar 22.
The initial step of the plastidic 2C-methyl-D-erythritol 4-phosphate (MEP) pathway that produces isopentenyl diphosphate is catalyzed by 1-deoxy-d-xylulose-5-phosphate synthase. To investigate whether or not 1-deoxy-d-xylulose-5-phosphate synthase catalyzes a limiting step in the MEP pathway in plants, we produced transgenic Arabidopsis plants that over- or underexpress this enzyme. Compared with non-transgenic wild-type plants, the transgenic plants accumulate different levels of various isoprenoids such as chlorophylls, tocopherols, carotenoids, abscisic acid, and gibberellins. Phenotypically, the transgenic plants had slight alterations in growth and germination rates. Because the levels of several plastidic isoprenoids correlate with changes in 1-deoxy-D-xylulose-5-phosphate synthase levels, we conclude that this enzyme catalyzes one of the rate-limiting steps of the MEP biosynthetic pathway. Furthermore, since the product of the MEP pathway is isopentenyl diphosphate, our results suggest that in plastids the pool of isopentenyl diphosphate is limiting to isprenoid production.
质体2C-甲基-D-赤藓糖醇-4-磷酸（MEP）途径产生异戊烯基二磷酸的第一步反应由1-脱氧-D-木酮糖-5-磷酸合酶催化。为了研究1-脱氧-D-木酮糖-5-磷酸合酶是否催化植物MEP途径中的限速步骤，我们培育了该酶过表达或低表达的转基因拟南芥植株。与非转基因野生型植株相比，转基因植株积累了不同水平的各种类异戊二烯，如叶绿素、生育酚、类胡萝卜素、脱落酸和赤霉素。在表型上，转基因植株在生长和发芽率方面有轻微改变。由于几种质体类异戊二烯的水平与1-脱氧-D-木酮糖-5-磷酸合酶水平的变化相关，我们得出结论，该酶催化MEP生物合成途径的限速步骤之一。此外，由于MEP途径的产物是异戊烯基二磷酸，我们的结果表明，在质体中异戊烯基二磷酸库限制了类异戊二烯的产生。
