Plant Global Educational Project, Nara Institute of Science and Technology, Ikoma, Japan.
Plant Signal Behav. 2011 Sep;6(9):1253-5. doi: 10.4161/psb.6.9.16529.
Although zinc is an essential micronutrient for all living organisms, zinc is harmful to cells at high levels. In the presence of excess zinc, plants exhibit several major symptoms, including root growth inhibition, abnormal root hair morphology and chlorosis. To dissect the molecular mechanisms underlying the effects of excess zinc on plant cells, we used aniTRA Q-based quantitative proteomics approach to analyze the microsomal protein profiles of Arabidopsis roots from wild-type (WT) plants and de-etiolated 3-1 (det3-1), a vacuolar H+ -AT Pase (V-AT Pase) subunit C-defective mutant. A comparative analysis of the iTRA Q data from WT and det3-1 plants exposed to excess zinc suggests that the reduction in V-AT Pase subunit levels and its activity are the cause of the symptoms of zinc toxicity, including the inhibition of cell expansion. Provided that reduced V-AT Pase activity in the trans-Golgi network (TGN) alone can inhibit cell expansion, it is possible that the det3-1 mutant phenotype is caused mainly by a defect in TGN acidification, leading to reduced cell wall component trafficking and cell expansion in the presence of excess zinc. To evaluate the contribution of V-AT Pase activity to vacuolar acidification under excess zinc, the vacuolar pH was measured. Our results indicate clear alkalinization of deep cell vacuoles treated with 300 μM ZnSO4.
虽然锌是所有生物体必需的微量元素，但高水平的锌对细胞是有害的。在锌过量的情况下，植物会表现出几种主要症状，包括根生长抑制、异常根毛形态和黄化。为了剖析过量锌对植物细胞影响的分子机制，我们使用 aniTRA Q 基于定量蛋白质组学方法分析了来自野生型（WT）植物和去黄化 3-1（det3-1）的拟南芥根的微粒体蛋白图谱，det3-1 是液泡 H+ -ATP 酶（V-ATPase）亚基 C 缺陷突变体。对暴露于过量锌的 WT 和 det3-1 植物的 iTRA Q 数据进行比较分析表明，V-ATPase 亚基水平及其活性的降低是锌毒性症状的原因，包括细胞扩张的抑制。假设 TGN 中 V-ATPase 活性的降低本身就可以抑制细胞扩张，那么 det3-1 突变体的表型可能主要是由于 TGN 酸化缺陷导致的，在过量锌存在的情况下，导致细胞壁成分运输和细胞扩张减少。为了评估 V-ATPase 活性对过量锌下液泡酸化的贡献，测量了液泡 pH 值。我们的结果表明，用 300 μM ZnSO4 处理的深层细胞液泡明显碱化。
