Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001 Chamilpa. Apdo. Postal 510-3 Cuernavaca, Morelos 62210, Mexico.
J Exp Bot. 2011 Mar;62(6):2023-38. doi: 10.1093/jxb/erq393. Epub 2011 Jan 3.
The 1-deoxy-D-xylulose 5-phosphate synthase (DXS) enzyme catalyses the first biosynthetic step of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. In plants the MEP pathway is involved in the synthesis of the common precursors to the plastidic isoprenoids, isopentenyl diphosphate and dimethylallyl diphosphate, in plastids. DXS is recognized as limiting this pathway and is a potential target for manipulation to increase various isoprenoids such as carotenoids. In Zea mays three dxs genes exist that encode plastid-targeted functional enzymes. Evidence is provided that these genes represent phylogenetically distinctive clades conserved among plants preceding monocot-dicot divergence. There is differential accumulation for each dxs gene transcript, during development and in response to external signals such as light. At the protein level, the analysis demonstrates that in Z. mays, DXS protein is feedback regulated in response to the inhibition of the pathway flow. The results support that the multilevel regulation of DXS activity is conserved in evolution.
1-脱氧-D-木酮糖 5-磷酸合酶（DXS）酶催化 2-C-甲基-D-赤藓醇 4-磷酸（MEP）途径的第一个生物合成步骤。在植物中，MEP 途径参与质体异戊烯基二磷酸和二甲基烯丙基二磷酸等质体类异戊二烯前体的合成。DXS 被认为限制了这条途径，是操纵该途径以增加各种类异戊二烯（如类胡萝卜素）的潜在目标。在玉米中，存在三个编码质体靶向功能酶的 dxs 基因。有证据表明，这些基因代表了在单子叶植物和双子叶植物分化之前，植物中具有系统发育独特分支的基因。在发育过程中和对外界信号（如光照）的反应中，每个 dxs 基因转录本的积累情况都不同。在蛋白质水平上，分析表明，在玉米中，DXS 蛋白对途径流动的抑制作用具有反馈调节作用。结果支持 DXS 活性的多层次调节在进化中是保守的。
