Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
The Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
New Phytol. 2012 Apr;194(2):430-439. doi: 10.1111/j.1469-8137.2012.04052.x. Epub 2012 Feb 1.
The shikimate pathway of plants mediates the conversion of primary carbon metabolites via chorismate into the three aromatic amino acids and to numerous secondary metabolites derived from them. However, the regulation of the shikimate pathway is still far from being understood. We hypothesized that 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) is a key enzyme regulating flux through the shikimate pathway. To test this hypothesis, we expressed a mutant bacterial AroG gene encoding a feedback-insensitive DAHPS in transgenic Arabidopsis plants. The plants were subjected to detailed analysis of primary metabolism, using GC-MS, as well as secondary metabolism, using LC-MS. Our results exposed a major effect of bacterial AroG expression on the levels of shikimate intermediate metabolites, phenylalanine, tryptophan and broad classes of secondary metabolite, such as phenylpropanoids, glucosinolates, auxin and other hormone conjugates. We propose that DAHPS is a key regulatory enzyme of the shikimate pathway. Moreover, our results shed light on additional potential metabolic bottlenecks bridging plant primary and secondary metabolism.
植物的莽草酸途径通过分支酸将初级碳代谢物转化为三种芳香族氨基酸，并进一步转化为许多衍生自它们的次级代谢物。然而，莽草酸途径的调控机制仍远未被完全理解。我们假设 3-脱氧-D-阿拉伯庚酮糖-7-磷酸合酶（DAHPS）是调控莽草酸途径通量的关键酶。为了验证这一假设，我们在转基因拟南芥植物中表达了一种编码反馈不敏感 DAHPS 的突变体细菌 AroG 基因。利用 GC-MS 对植物进行了初级代谢物的详细分析，以及利用 LC-MS 对次级代谢物进行了分析。我们的结果表明，细菌 AroG 表达对莽草酸中间代谢物、苯丙氨酸、色氨酸和广泛的次级代谢物（如苯丙素类、硫代葡萄糖苷、生长素和其他激素缀合物）的水平有重大影响。我们提出 DAHPS 是莽草酸途径的关键调节酶。此外，我们的结果揭示了连接植物初级和次级代谢的其他潜在代谢瓶颈。
