2 AUXIN-RESPONSIVE DOMAINS INTERACT POSITIVELY TO INDUCE EXPRESSION OF THE EARLY INDOLEACETIC ACID-INDUCIBLE GENE PS-IAA4/5
2 AUXIN-RESPONSIVE DOMAINS INTERACT POSITIVELY TO INDUCE EXPRESSION OF THE EARLY INDOLEACETIC ACID-INDUCIBLE GENE PS-IAA4/5
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DOI：
10.1073/pnas.92.8.3483
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发表时间：
1995-04-11
影响因子：
11.1
通讯作者：
THEOLOGIS, A
中科院分区：
文献类型：
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作者：
BALLAS, N;WONG, LM;THEOLOGIS, A
植物生长激素吲哚-3-乙酸（IAA）通过转录激活植物中几种基因的表达。我们之前在ps - ia4a /5基因中发现了一个164-bp的启动子区域（-318至-154），该区域具有IAA诱导性。整个区域的链接扫描突变鉴定出两个阳性结构域：结构域A （48 bp； -203至-156）和结构域B (44 bp； -299至-256)，它们负责IAA对ps - ia4a /5的转录激活。结构域A包含在各种iaa诱导基因中发现的高度保守序列5'-TGTCCCAT-3'，是生长素反应的主要元件。结构域B作为一个增强元件，它也可能包含一个效率较低的生长素响应元件。这两个结构域协同作用以刺激转录；然而，结构域A或B的四聚化弥补了A或B功能的丧失。这两个结构域还可以介导iaa诱导的异源花椰菜花叶病毒35S启动子转录（-73 ~ +1）。A或B结构域20同构象的体内竞争实验表明，这两个结构域与低丰度的阳性转录因子具有特异性和不同的亲和力。讨论了IAA对ps - ia4a /5的转录激活模型。
The plant growth hormone indole-3-acetic acid (IAA) transcriptionally activates expression of several genes in plants. We have previously identified a 164-bp promoter region (-318 to -154) in the PS-IAA4/5 gene that confers IAA inducibility. Linker-scanning mutagenesis across the region has identified two positive domains: domain A (48 bp; -203 to -156) and domain B (44 bp; -299 to -256), responsible for transcriptional activation of PS-IAA4/5 by IAA. Domain A contains the highly conserved sequence 5'-TGTCCCAT-3' found among various IAA-inducible genes and behaves as the major auxin-responsive element. Domain B functions as an enhancer element which may also contain a less efficient auxin-responsive element. The two domains act cooperatively to stimulate transcription; however, tetramerization of domain A or B compensates for the loss of A or B function. The two domains can also mediate IAA-induced transcription from the heterologous cauliflower mosaic virus 35S promoter (-73 to +1). In vivo competition experiments with icosamers of domain A or B show that the domains interact specifically and with different affinities to low abundance, positive transcription factor(s). A model for transcriptional activation of PS-IAA4/5 by IAA is discussed.