Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
Phytochemistry. 2011 Jul;72(10):1081-91. doi: 10.1016/j.phytochem.2010.11.003. Epub 2010 Dec 10.
Plants reconfigure their metabolic network under stress conditions. Changes of mitochondrial metabolism such as tricarboxylic acid (TCA) cycle and amino acid metabolism are reported in Arabidopsis roots but the exact molecular basis underlying this remains unknown. We here hypothesise the reassembly of enzyme protein complexes to be a molecular mechanism for metabolic regulation and tried in the present study to find out mitochondrial protein complexes which change their composition under oxidative stress by the combinatorial approach of proteomics and metabolomics. Arabidopsis seedlings were treated with menadione to induce oxidative stress. The inhibition of several TCA cycle enzymes and the oxidised NADPH pool indicated the onset of oxidative stress. In blue native/SDS-PAGE analysis of mitochondrial protein complexes the intensities of 18 spots increased and those of 13 spots decreased in menadione treated samples suggesting these proteins associate with, or dissociate from, protein complexes. Some spots were identified as metabolic enzymes related to central carbon metabolism such as malic enzyme, glyceraldehyde-3-phosphate dehydrogenase, monodehydroascorbate reductase and alanine aminotransferase. The change in spot intensity was not directly correlated to the total enzyme activity and mRNA level of the corresponding enzyme but closely related to the metabolite profile, suggesting the metabolism is regulated under oxidative stress at a higher level than translation. These results are somewhat preliminary but suggest the regulation of the TCA cycle, glycolysis, ascorbate and amino acid metabolism by reassembly of plant enzyme complexes.
植物在胁迫条件下重新配置其代谢网络。已报道拟南芥根中存在线粒体代谢（如三羧酸循环和氨基酸代谢）的变化，但确切的分子基础尚不清楚。我们假设酶蛋白复合物的重新组装是代谢调控的分子机制，本研究试图通过蛋白质组学和代谢组学的组合方法，找出在氧化胁迫下线粒体蛋白复合物的组成发生变化的原因。用 menadione 处理拟南芥幼苗以诱导氧化应激。几种 TCA 循环酶的抑制作用和氧化的 NADPH 池表明氧化应激的发生。在线粒体蛋白复合物的蓝色非变性/SDS-PAGE 分析中，18 个斑点的强度增加，13 个斑点的强度降低，表明这些蛋白质与蛋白复合物结合或解离。一些斑点被鉴定为与中心碳代谢相关的代谢酶，如苹果酸酶、甘油醛-3-磷酸脱氢酶、单脱氢抗坏血酸还原酶和丙氨酸转氨酶。斑点强度的变化与相应酶的总酶活性和 mRNA 水平没有直接相关性，但与代谢物图谱密切相关，表明在翻译水平之上，代谢在氧化胁迫下受到更精细的调控。这些结果有些初步，但表明植物酶复合物的重新组装调节三羧酸循环、糖酵解、抗坏血酸和氨基酸代谢。
