The as-1 promoter element is an oxidative stress-responsive element and salicylic acid activates it via oxidative species
The as-1 promoter element is an oxidative stress-responsive element and salicylic acid activates it via oxidative species
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DOI：
10.1104/pp.009886
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发表时间：
2002-11-01
期刊：
影响因子：
7.4
通讯作者：
Holuigue, L
中科院分区：
文献类型：
--
作者：
Garretón, V;Carpinelli, J;Holuigue, L
在某些谷胱甘肽 S-转移酶 (GST) 基因的启动子中发现的激活序列 1 (as-1) 样元件先前已被描述为水杨酸 (SA) 和生长素响应元件。在本文中，我们测试了 SA 对 as-1 元素的激活作用是由氧化物质介导的假设。我们的结果支持这一假设，结果表明抗氧化剂二甲基硫脲 (DMTU) 和 3-叔丁基-4-羟基苯唑 (BHA) 抑制 SA 诱导的烟草 (Nicotiana tabacum) 植物中由 as-1 元件控制的基因转录。编码 GST 和 (as-1)(4)/β-葡萄糖醛酸酶 (GUS) 报告转基因的 GNT35 基因]。 DMTU 和 BHA 还可抑制核提取物中 SA 激活的 as-1 结合活性。我们的结果进一步支持了 as-1 元件被氧化物质激活的假设，该结果表明光增强了 SA 诱导的 as-1 元件的激活。此外，甲基紫精（一种已知的植物氧化应激诱导剂）也会激活 as-1 元素。通过与 H2O2 或过氧化氢酶抑制剂 3-氨基-1,2,5-三唑一起孵育来增加 H2O2 水平不会激活 (as-1)(4)/GUS 基因。相反，3-氨基-1,2,5-三唑抑制SA对(as-1)(4)/GUS基因的激活作用。这些结果表明除 H2O2 之外的氧化物质通过 SA 介导 as-1 元件的激活。我们的结果还表明，即使 as-1 结合活性受到氧化物质的刺激，但这不足以对该元件控制的基因进行反式激活。讨论了 SA 和活性氧在防御基因转录激活中的复杂相互作用。
The activation sequence-1 (as-1)-like element found in the promoter of some glutathione S-transferase (GST) genes, has been previously described as a salicylic acid (SA)- and auxin-responsive element. In this paper, we tested the hypothesis that the activating effect of SA on the as-1 element is mediated by oxidative species. Supporting this hypothesis, our results show that the antioxidants dimethylthiourea (DMTU) and 3-t-butyl-4-hydroxy-anizole (BHA) inhibit the SA-induced transcription of genes controlled by as-1 elements in tobacco (Nicotiana tabacum) plants [i.e. GNT35 gene coding for a GST and (as-1)(4)/beta-glucuronidase (GUS) reporter transgene]. DMTU and BHA also inhibit SA-activated as-1-binding activity in nuclear extracts. Further support for the hypothesis that the as-1 element is activated by oxidative species comes from our result showing that light potentiates the SA-induced activation of the as-1 element. Furthermore, methyl viologen, a known oxidative stress inducer in plants, also activates the as-1 element. Increasing H2O2 levels by incubation with H2O2 or with the catalase inhibitor 3-amino-1,2,5-triazole does not activate the (as-1)(4)/GUS gene. On the contrary, 3-amino-1,2,5-triazole inhibits the activating effect of SA on the (as-1)(4)/GUS gene. These results suggest that oxidative species other than H2O2 mediate the activation of the as-1 element by SA. Our results also suggest that even though the as-1 binding activity is stimulated by oxidative species, this is not sufficient for the transactivation of genes controlled by this element. The complex interplay between SA and reactive oxygen species in the transcriptional activation of defense genes is discussed.