Isolation and characterization of IRO2, a novel iron-regulated bHLH transcription factor in graminaceous plants
Isolation and characterization of IRO2, a novel iron-regulated bHLH transcription factor in graminaceous plants
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DOI：
10.1093/jxb/erl054
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发表时间：
2006-08-01
影响因子：
6.9
通讯作者：
Nishizawa, Naoko K.
中科院分区：
文献类型：
--
作者：
Ogo, Yuko;Itai, Reiko Nakanishi;Nishizawa, Naoko K.
为了阐明调节禾本科植物铁 (Fe) 获取的分子机制，使用水稻 22K 寡 DNA 微阵列对缺铁胁迫期间的基因表达进行了时程分析。缺铁诱导了 21 个具有基因调控功能的蛋白质基因。在这些基因中，一个假定的碱性螺旋-环-螺旋（bHLH）转录因子基因，名为OsIRO2，在缺铁胁迫期间在根和芽中强烈表达。 OsIRO2 的表达仅由 Fe 缺乏诱导，而不是由其他金属缺乏诱导。大麦 HvIRO2 基因（OsIRO2 的同源物）的表达也是由 Fe 缺乏诱导的。计算机搜索显示，IRO2 在小麦、高粱和玉米等禾本科植物中高度保守。循环扩增和靶点选择 (CASTing) 技术显示 OsIRO2 优先结合序列 5'-ACCACGTGGTTTT-3'，电泳迁移率变动分析显示 5'-CACGTGG-3' 是 OsIRO2 结合的核心序列。在参与 Fe 获取的几个基因的上游发现了与 OsIRO2 结合序列相似的序列，例如 OsNAS1、OsNAS3、OsIRT1、OsFDH、OsAPT1 和 IDS3。 OsIRO2结合序列的核心序列在Fe缺乏诱导基因的上游区域中比在非诱导基因的相应区域中更频繁地出现。这些结果表明 IRO2 参与缺铁条件下基因表达的调节。
To clarify the molecular mechanism that regulates iron (Fe) acquisition in graminaceous plants, a time-course analysis of gene expression during Fe deficiency stress was conducted using a rice 22K oligo-DNA microarray. Twenty-one genes for proteins that function in gene regulation were induced by Fe deficiency. Of these genes, a putative basic helix-loop-helix (bHLH) transcription factor gene, named OsIRO2, was strongly expressed in both roots and shoots during Fe deficiency stress. The expression of OsIRO2 was induced exclusively by Fe deficiency, and not by deficiencies in other metals. Expression of the barley HvIRO2 gene, which is a homologue of OsIRO2, was also induced by Fe deficiency. An in silico search revealed that IRO2 is highly conserved among graminaceous plants, which include wheat, sorghum, and maize. The cyclic amplification and selection of targets (CASTing) technique revealed that OsIRO2 bound preferentially to the sequence 5'-ACCACGTGGTTTT-3', and the electrophoretic mobility shift assay revealed 5'-CACGTGG-3' as the core sequence for OsIRO2 binding. Sequences similar to the OsIRO2-binding sequence were found upstream of several genes that are involved in Fe acquisition, such as OsNAS1, OsNAS3, OsIRT1, OsFDH, OsAPT1, and IDS3. The core sequence of the OsIRO2-binding sequence occurred more frequently in the upstream regions of Fe deficiency-inducible genes than in the corresponding regions of non-inducible genes. These results suggest that IRO2 is involved in the regulation of gene expression under Fe-deficient conditions.