COMPOSITE STRUCTURE OF AUXIN RESPONSE ELEMENTS
COMPOSITE STRUCTURE OF AUXIN RESPONSE ELEMENTS
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DOI：
10.1105/tpc.7.10.1611
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发表时间：
1995-10-01
期刊：
影响因子：
11.6
通讯作者：
GUILFOYLE, TJ
中科院分区：
文献类型：
--
作者：
ULMASOV, T;LIU, ZB;GUILFOYLE, TJ
生长素响应型大豆GH 3基因启动子由多个生长素响应元件（auxin response elements，EREs）组成，每个EREs对启动子的强生长素诱导作用有递增的贡献。25 bp（D1）和32 bp（D4）的两个独立的引物含有序列TGTCTC。结果表明，在D1和D4中的TGTCTC元件是必需的，但不足以在胡萝卜原生质体瞬时表达试验中诱导生长素。TGTCTC上游的额外核苷酸也是生长素诱导所必需的。当TGTCTC元件的部分或全部突变或缺失时，这些上游序列显示组成型活性并且没有生长素诱导。在D1中，组成元件与TGTCTC的5'部分重叠;在D4中，组成元件与TGTCTC分离。D1中的一个11 bp元件，CCTCGTGTCTC，在转基因烟草幼苗以及胡萝卜原生质体中赋予生长素对最小花椰菜花叶病毒35 S启动子的诱导作用（即，瞬时表达测定）。这两个组成元件都与植物核蛋白特异性结合，并且D1中的组成元件与具有G-box特异性的重组大豆碱性亮氨酸拉链转录因子结合。为了进一步证明AuxRE的复合性质和TGTCTC元件赋予生长素诱导能力的能力，我们通过将酵母GAL 4 DNA结合位点放置在TGTCTC元件附近来创建新型AuxRE。GAL 4-c-Rel反式激活因子的表达在这种新的ECONORE的存在下导致生长素诱导的表达。我们的研究结果表明，至少有一些ESTREs具有复合结构组成的一个保守的TGTCTC元件，赋予生长素诱导相邻的组成元件。
The auxin-responsive soybean GH3 gene promoter is composed of multiple auxin response elements (AuxREs), and each AuxRE contributes incrementally to the strong auxin inducibility of the promoter. Two independent AuxREs of 25 bp (D1) and 32 bp (D4) contain the sequence TGTCTC. Results presented here show that the TGTCTC element in D1 and D4 is required but not sufficient for auxin inducibility in carrot protoplast transient expression assays. Additional nucleotides upstream of TGTCTC are also required for auxin inducibility. These upstream sequences showed constitutive activity and no auxin inducibility when part or all of the TGTCTC element was mutated or deleted. In D1, the constitutive element overlaps the 5' portion of TGTCTC; in D4, the constitutive element is separated from TGTCTC. An 11-bp element in D1, CCTCGTGTCTC, conferred auxin inducibility to a minimal cauliflower mosaic virus 35S promoter in transgenic tobacco seedlings as well as in carrot protoplasts (i.e., transient expression assays). Both constitutive elements bound specifically to plant nuclear proteins, and the constitutive element in D1 bound to a recombinant soybean basic leucine zipper transcription factor with G-box specificity. To demonstrate further the composite nature of AuxREs and the ability of the TGTCTC element to confer auxin inducibility, we created a novel AuxRE by placing a yeast GAL4 DNA binding site adjacent to the TGTCTC element. Expression of a GAL4-c-Rel transactivator in the presence of this novel AuxRE resulted in auxin-inducible expression. Our results indicate that at least some AuxREs have a composite structure consisting of a constitutive element adjacent to a conserved TGTCTC element that confers auxin inducibility.