Interaction between composite elements in the napA promoter:: both the B-box ABA-responsive complex and the RY/G complex are necessary for seed-specific expression
Interaction between composite elements in the napA promoter:: both the B-box ABA-responsive complex and the RY/G complex are necessary for seed-specific expression
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DOI：
10.1023/a:1006206124512
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发表时间：
1999-07-01
影响因子：
5.1
通讯作者：
Rask, L
中科院分区：
文献类型：
--
作者：
Ezcurra, I;Ellerström, M;Rask, L
在种子成熟过程中，napin基因的转录活性受到转录激活因子ABI3和脱落酸（ABA）等发育信号的调控。为了定位与napin napA启动子种子特异性活性相关的顺式元件，我们对两个主要元件复合物B-box和RY/G进行了系统分析。在稳定转基因烟草中利用启动子-报告基因融合进行的替代突变分析表明，这些复合物中的元件之间存在协同作用。B-box的远端部分与脱落酸响应元素相似，近端部分含有富ca元素。体外研究包括核酸外切酶III保护和电泳迁移转移分析显示核蛋白与b盒内元素的结合。发现B-box的远端和近端结合不同的核蛋白复合物。通过与截断的（-46）花菜花叶病毒（CaMV） 35S最小启动子融合的B-box四聚体的功能获得分析，证明B-box在种子中具有很强的活性。此外，研究表明B-box中的元件构成aba应答复合物，因为B-box四聚体介导营养组织对含有CaMV病毒35S增强子（-343至-90）的构建体的aba应答。因此，napA启动子的种子特异性活性依赖于种子发育中ABA应答过程中RY/G复合物和B-box ABA应答复合物之间的组合相互作用。
During seed maturation, the transcriptional activity of napin genes is regulated by developmental signals involving the transcriptional activator ABI3 and abscisic acid (ABA). To localize cis elements involved in the seed-specific activity of the napin napA promoter, a systematic analysis was performed focusing on two major element complexes, the B-box and RY/G. Substitution mutation analysis using promoter-reporter gene fusions in stable transgenic tobacco showed synergistic interactions between elements within these complexes. The distal part of the B-box shows similarities to abscisic acid response elements and the proximal portion contains a CA-rich element. In vitro studies involving Exonuclease III protection and electrophoretic mobility shift assays revealed binding by nuclear proteins to elements within the B-box. The distal and proximal parts of the B-box were found to bind distinct nuclear protein complexes. By gain-of-function analysis with a tetramer of the B-box fused to a truncated (-46) cauliflower mosaic virus (CaMV) 35S minimal promoter, it was demonstrated that the B-box mediates strong activity in seeds. Further, it was shown that the elements in the B-box constitute an ABA-responsive complex, since the B-box tetramer mediates ABA-responsiveness in vegetative tissues to a construct containing the CaMV virus 35S enhancer (-343 to -90). Thus, the seed-specific activity of the napA promoter relies on the combinatorial interaction between the RY/G complex and the B-box ABA-responsive complex during the ABA response in seed development.