Department of Plant Physiology, Institute of Plant Biology, University of Wrocław, Kanonia 6/8, 50-328 Wrocław, Poland.
J Exp Bot. 2012 Jun;63(11):4133-42. doi: 10.1093/jxb/ers097. Epub 2012 Mar 26.
The effect of heavy metals on plasma membrane (PM) H(+)-ATPase (EC 3.6.3.14) activity in cucumber (Cucumis sativus) roots was studied. The aim of this work was to explain the mechanism of modification of the PM H(+)-ATPase activity in plants subjected to heavy metals. Plants were treated with 10 μM Cd or Cu for 6 d. After 3 d exposure to the heavy metals, some of the plants were transferred to control conditions for a further 3 d (3/3 plants). The activity of PM H(+)-ATPase was found to be increased in plants treated with heavy metals. The highest activity measured as proton transport was observed in 3/3 plants. Estimation of transcript levels of C. sativus PM H(+)-ATPase in roots indicated that the action of Cd, but not Cu, affected the gene expression level. Transcript levels of C. sativus PM H(+)-ATPase (CsHA2, CsHA3, CsHA4, CsHA8, and CsHA9) genes increased in roots treated with Cd. Moreover, Western blot analysis with antibody against phosphothreonine and 14-3-3 protein indicated that increased activity of PM H(+)-ATPase under heavy-metal stress resulted from phosphorylation of the enzyme. It was found that Cu markedly increased the activity of catalase and ascorbate peroxidase and reduced the level of H(2)O(2) in cucumber roots. In contrast, Cd did not affect these parameters. These results indicate that Cd and Cu can, in different ways, lead to modification of PM H(+)-ATPase activity. Additionally, it was observed that treatment of plants with heavy metals led to an increased level of heat-shock proteins in the tissues. This suggests that the plants had started adaptive processes to survive adverse conditions, and increased PM H(+)-ATPase activity could further enhance the repair processes in heavy-metal-stressed plants.
研究了重金属对黄瓜（Cucumis sativus）根系质膜（PM）H(+) - ATP 酶（EC 3.6.3.14）活性的影响。本工作旨在解释重金属处理后植物质膜 H(+) - ATP 酶活性变化的机制。用 10 μM Cd 或 Cu 处理植物 6 天。在暴露于重金属 3 天后，一些植物被转移到对照条件下再培养 3 天（3/3 植物）。结果发现，重金属处理的植物中 PM H(+) - ATP 酶活性增加。在 3/3 植物中观察到质子转运的最高活性。对根系中 C. sativus PM H(+) - ATP 酶的转录水平进行估计表明，Cd 的作用而非 Cu 的作用影响基因表达水平。用 Cd 处理的根系中 C. sativus PM H(+) - ATP 酶（CsHA2、CsHA3、CsHA4、CsHA8 和 CsHA9）基因的转录水平增加。此外，用针对磷酸苏氨酸和 14-3-3 蛋白的抗体进行的 Western blot 分析表明，重金属胁迫下 PM H(+) - ATP 酶活性的增加是由于酶的磷酸化所致。研究发现，Cu 显著增加了过氧化氢酶和抗坏血酸过氧化物酶的活性，降低了黄瓜根系中的 H(2)O(2)水平。相比之下，Cd 没有影响这些参数。这些结果表明，Cd 和 Cu 可以以不同的方式导致 PM H(+) - ATP 酶活性的改变。此外，还观察到重金属处理会导致组织中热休克蛋白水平升高。这表明植物已经开始适应不良条件的过程，增加的 PM H(+) - ATP 酶活性可以进一步增强重金属胁迫下植物的修复过程。
