Ntlim1, a PAL-box binding factor, controls promoter activity of the horseradish wound-inducible peroxidase gene
Ntlim1, a PAL-box binding factor, controls promoter activity of the horseradish wound-inducible peroxidase gene
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DOI：
10.1023/a:1015504515492
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发表时间：
2002-08-01
影响因子：
5.1
通讯作者：
Shinmyo, A
中科院分区：
文献类型：
--
作者：
Kaothien, P;Kawaoka, A;Shinmyo, A
为了了解伤害诱导植物过氧化物酶基因表达的分子机制，分析了辣根C2过氧化物酶(PrxC2)基因的启动子。我们以前已经分离到一个烟草核蛋白Ntlim1，作为与prxC2启动子的PAL盒基序结合的反式因子；然而，Ntlim1反式因子和PAL盒基序在prxC2基因创伤反应表达中的作用尚不清楚。在这里，我们发现没有完整PAL-box基序的prxC2启动子不能在转基因烟草中引导基础和伤害诱导的报告基因β-葡萄糖醛酸酶(GUS)的正常表达，这表明PAL-box基序是prxC2启动子的一个基本顺式元件。我们还发现，在携带prxC2启动子：：GUS嵌合结构的转基因植物中，Ntlim1的反义表达不仅降低了GUS报告基因的基础和创伤诱导表达水平，而且降低了prxC2启动子本身的创伤诱导程度。这一结果表明，Ntlim1是PrxC2启动子活性基础水平所必需的，也是创伤应激下上调prxC2启动子活性所必需的。此外，与在PLANTA中得到的结果一致，超位移实验结果表明，Ntlim1与PAL-box基序结合不受创伤压力的影响。
To understand molecular mechanisms underlying wound-induced expression of plant peroxidase genes, the promoter of a horseradish C2 peroxidase (prxC2) gene was analyzed. We had previously isolated a tobacco nuclear protein, Ntlim1, as a trans factor binding to a PAL-box motif of the prxC2 promoter; however, the function of the Ntlim1 trans factor and the PAL-box motif in wound-responsive expression of the prxC2 gene remains unclear. Here, we found that the prxC2 promoter without the intact PAL-box motif failed to direct a normal level of both the basal and the wound-induced expression of beta-glucuronidase (GUS) reporter gene in transgenic tobacco plants, indicating that the PAL-box motif functions as an essential cis element of the prxC2 promoter. We also found that antisense expression of Ntlim1 in transgenic plants carrying the prxC2 promoter::GUS chimeric construct decreased not only the level of the basal and the wound-induced expression of the GUS reporter gene but also the extent of wound inducibility of the prxC2 promoter itself. This result indicates that Ntlim1 is required for the basal level of prxC2 promoter activity as well as its up-regulation under wound stress. Moreover, consistent with the results obtained in planta, result from super-shift assay indicates that the Ntlim1 binds to the PAL-box motif independently of wound stress.