Target genes for OBP3, a Dof transcription factor, include novel basic helix-loop-helix domain proteins inducible by salicylic acid
Target genes for OBP3, a Dof transcription factor, include novel basic helix-loop-helix domain proteins inducible by salicylic acid
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DOI：
10.1046/j.1365-313x.2003.01812.x
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发表时间：
2003-08-01
期刊：
影响因子：
7.2
通讯作者：
Singh, KB
中科院分区：
文献类型：
--
作者：
Kang, HG;Foley, RC;Singh, KB
水杨酸（SA）诱导的拟南芥DNA与一指（Dof）转录因子（称为obf结合蛋白3 (OBP3; AtDof3.6)）结合的过表达，先前已被证明会导致生长缺陷。本研究采用抑制减法杂交（SSH）分离obp3过表达系诱导的基因，并分离出几个假定的克隆，称为obp3应答基因（ORGs）。通过分析额外的OBP3过表达系，证实了这些基因的诱导表达水平与OBP3过表达之间的联系。ORG1 ~ ORG4为新基因，而ORG5为延伸蛋白AtExt1。虽然ORG4与数据库中的其他蛋白没有相似性，但ORG1在预测蛋白的不同区域与CDC2和原纤维蛋白有弱相似性。ORG2和ORG3在推导出的氨基酸序列中有80%的一致性，并且含有基本的螺旋-环-螺旋dna结合域，表明ORG2和ORG3可能是转录因子。在所有检测条件下，包括SA上调和茉莉酸（JA）下调，ORG1、ORG2和ORG3基因的表达均受到共同调控。为了进一步探索OBP3的功能，我们生成了15条OBP3沉默线。虽然这些品系没有明显的表型变化，但ORG1、ORG2和ORG3的表达减少。ORG基因中，ORG1、ORG2和ORG3在启动子区含有最多的潜在dof结合位点，使用诱导启动子系统诱导OBP3表达后3 h内表达量显著增加，与外源OBP3蛋白的表达水平密切相关。功能获得和功能丧失实验结果表明，ORG1、ORG2和ORG3基因是OBP3的直接靶基因。
Overexpression of a salicylic-acid (SA)-inducible Arabidopsis DNA binding with one finger (Dof) transcription factor, called OBF-binding protein 3 (OBP3; AtDof3.6), has previously been shown to result in growth defects. In this study, suppressive subtraction hybridization (SSH) was used to isolate genes induced in an OBP3-overexpression line and several putative clones, called OBP3-responsive genes (ORGs), were isolated. The link with the induced expression levels of these genes and OBP3 overexpression was confirmed by analysing additional OBP3-overexpression lines. ORG1 through ORG4 are novel genes, while ORG5 is an extensin gene, AtExt1 . While ORG4 has no similarity with other proteins in the database, ORG1 has weak similarity in different regions of the predicted protein with CDC2 and fibrillin. ORG2 and ORG3 share 80% overall identity in their deduced amino acid sequences and contain a basic helix-loop-helix DNA-binding domain, suggesting that ORG2 and ORG3 may be transcription factors. The expression of the ORG1, ORG2 and ORG3 genes was co-regulated under all conditions examined including upregulation by SA and downregulation by jasmonic acid (JA). Fifteen OBP3-silenced lines were generated to further explore the function of OBP3. Although there were no visible phenotypic changes in any of these lines, the expression of ORG1, ORG2 and ORG3 was reduced. Among the ORG genes, ORG1, ORG2 and ORG3 contained the highest number of potential Dof-binding sites in the promoter region, and their expression was significantly increased within 3 h after induction of OBP3 expression using an inducible promoter system, and closely reflected the expression levels of the exogenous OBP3 protein. The results from the gain-of-function and loss-of-function experiments suggest that the ORG1, ORG2 and ORG3 genes are direct target genes of OBP3.