Identification of novel cis-acting elements, IDE1 and IDE2, of the barley IDS2 gene promoter conferring iron-deficiency-inducible, root-specific expression in heterogeneous tobacco plants
Identification of novel cis-acting elements, IDE1 and IDE2, of the barley IDS2 gene promoter conferring iron-deficiency-inducible, root-specific expression in heterogeneous tobacco plants
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DOI：
10.1046/j.1365-313x.2003.01920.x
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发表时间：
2003-12-01
期刊：
影响因子：
7.2
通讯作者：
Nishizawa, NK
中科院分区：
文献类型：
--
作者：
Kobayashi, T;Nakayama, Y;Nishizawa, NK
植物响应铁（Fe）缺乏的分子机制仍然很大程度上未知。为了鉴定负责高等植物缺铁诱导表达的顺式作用元件，使用转基因烟草系统分析了大麦IDS2（缺铁特异性克隆2号）基因启动子。删除分析显示翻译起始位点(-272/-91)的-272和-91之间的序列对于烟草根中的特异性表达来说既是充分的也是必需的。该区域的进一步删除和接头扫描分析清楚地识别出两个顺式作用元件：-153/-136 (ATCAAGCATGCTTCTTGC) 处的缺铁反应元件 1 (IDE1) 和 -262/-236 处的 IDE2 (TTGAACGGCAAGTTTCACGCTGTCACT)。当使用 CaMV 35S 启动子的 -46/+8 区域（相对于转录起始位点）作为最小启动子时，IDE1 和 IDE2 的共存对于特异性表达至关重要。表达主要发生在根中柱鞘、内皮层和皮层。当 CaMV 35S 启动子的 -90/+8 区域融合时，由 IDE2 和额外的 19 bp 组成的 -272/-227 区域可以在几乎整个根部驱动缺铁诱导表达，而无需 IDE1。 IDE1和IDE2的主要模块是同源的。在许多其他缺铁诱导启动子中也发现了与 IDE1 同源的序列，包括：烟酰胺转氨酶 (HvNAAT)-A、HvNAAT-B、烟酰胺合成酶 (HvNAS1)、HvIDS3、OsNAS1、OsNAS2、OsIRT1、AtIRT1 和 AtFRO2，表明顺式作用元件在各种基因和物种中的保守性。新型顺式作用元件 IDE1 和 IDE2 的鉴定将为阐明高等植物中调节 Fe 稳态的分子机制提供强大的工具。
The molecular mechanisms of plant responses to iron (Fe) deficiency remain largely unknown. To identify the cis-acting elements responsible for Fe-deficiency-inducible expression in higher plants, the barley IDS2 (iron deficiency specific clone no. 2) gene promoter was analyzed using a transgenic tobacco system. Deletion analysis revealed that the sequence between -272 and -91 from the translational start site (-272/-91) was both sufficient and necessary for specific expression in tobacco roots. Further deletion and linker-scanning analysis of this region clearly identified two cis-acting elements: iron-deficiency-responsive element 1 (IDE1) at -153/-136 (ATCAAGCATGCTTCTTGC) and IDE2 at -262/-236 (TTGAACGGCAAGTTTCACGCTGTCACT). The co-existence of IDE1 and IDE2 was essential for specific expression when the -46/+8 region (relative to the transcriptional start site) of the CaMV 35S promoter was used as a minimal promoter. Expression occurred mainly in the root pericycle, endodermis, and cortex. When the -90/+8 region of the CaMV 35S promoter was fused, the -272/-227 region, which consists of IDE2 and an additional 19 bp, could drive Fe-deficiency-inducible expression without IDE1 throughout almost the entire root. The principal modules of IDE1 and IDE2 were homologous. Sequences homologous to IDE1 were also found in many other Fe-deficiency-inducible promoters, including: nicotianamine aminotransferase (HvNAAT)-A, HvNAAT-B, nicotianamine synthase (HvNAS1), HvIDS3, OsNAS1, OsNAS2, OsIRT1, AtIRT1, and AtFRO2, suggesting the conservation of cis-acting elements in various genes and species. The identification of novel cis-acting elements, IDE1 and IDE2, will provide powerful tools to clarify the molecular mechanisms regulating Fe homeostasis in higher plants.