The roles of auxin response factor domains in auxin-responsive transcription
The roles of auxin response factor domains in auxin-responsive transcription
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DOI：
10.1105/tpc.008417
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发表时间：
2003-02-01
期刊：
影响因子：
11.6
通讯作者：
Guilfoyle, T
中科院分区：
文献类型：
--
作者：
Tiwari, SB;Hagen, G;Guilfoyle, T
生长素反应因子（ARFs）是早期生长素反应基因启动子中与TGTCTC生长素反应元件结合的转录因子。arf具有一个保守的n端DNA结合域（DBD）和一个保守的c端二聚化域（CTD）。ARF CTD在氨基酸序列上与Aux/IAA蛋白中的基序III和IV相关。就在DBD的C端，arf包含一个称为中间区域（MR）的非保守区域，该区域被认为是一个转录抑制或激活域。本文报道的转染原生质体的结果表明，富q MRs的arf起激活作用，而大多数（如果不是全部的话）其他arf起抑制作用。仅ARF dbd就足以将ARF招募到其DNA靶点，生长素不影响这种招募。当通过酵母Gal4 DBD靶向报告基因时，ARF MRs单独起激活或抑制作用，生长素不影响激活或抑制的效力。无论MRs + CTDs是由ARF DBD还是Gal4 DBD募集到启动子，ARF CTDs和富q MR都是生长素应答所必需的。生长素反应是通过将Aux/IAA蛋白募集到含有富含q - MR和附加CTD的DNA结合蛋白的启动子中来介导的。
Auxin response factors (ARFs) are transcription factors that bind to TGTCTC auxin response elements in promoters of early auxin response genes. ARFs have a conserved N-terminal DNA binding domain (DBD) and in most cases a conserved C-terminal dimerization domain (CTD). The ARF CTD is related in amino acid sequence to motifs III and IV found in Aux/IAA proteins. Just C terminal to the DBD, ARFs contain a nonconserved region referred to as the middle region (MR), which has been proposed to function as a transcriptional repression or activation domain. Results with transfected protoplasts reported here show that ARFs with Q-rich MRs function as activators, whereas most, if not all other ARFs, function as repressors. ARF DBDs alone are sufficient to recruit ARFs to their DNA target sites, and auxin does not influence this recruitment. ARF MRs alone function as activation or repression domains when targeted to reporter genes via a yeast Gal4 DBD, and auxin does not influence the potency of activation or repression. ARF CTDs, along with a Q-rich MR, are required for an auxin response whether the MRs plus CTDs are recruited to a promoter by an ARF DBD or by a Gal4 DBD. The auxin response is mediated by the recruitment of Aux/IAA proteins to promoters that contain a DNA binding protein with a Q-rich MR and an attached CTD.