Sequences flanking the hexameric G-box core CACGTG affect the specificity of protein binding.
Sequences flanking the hexameric G-box core CACGTG affect the specificity of protein binding.
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DOI：
10.1105/tpc.4.4.485
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发表时间：
1992-04
期刊：
影响因子：
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通讯作者：
Mary E. Williams;Randy Foster;N. Chua
中科院分区：
文献类型：
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作者：
Mary E. Williams;Randy Foster;N. Chua
CACGTG G-box 基序是一种高度保守的 DNA 序列，已在植物基因的 5' 上游区域中鉴定出，表现出受各种环境信号和生理线索的调节。使用一组侧翼序列不同的 G-box 寡核苷酸进行凝胶迁移率变动测定，鉴定出花椰菜核提取物中的两种类型的结合活性（A 和 B）。竞争凝胶阻滞测定证明两种类型的结合活性是不同的。 A型结合活性与指定为I类元件的寡核苷酸相互作用，而B型结合活性与II类元件强烈相互作用，与I类元件弱相互作用。第三类元素，无效元素，在我们的测定条件下没有表现出任何可检测到的结合。非回文杂合G-box寡核苷酸的凝胶阻滞分析表明，同一类杂合元件表现出与较弱元件的亲和力相当的结合亲和力，杂合I/II类元件仅表现出B型结合，杂合I类/无效元件和II类/无效元件没有表现出任何可检测的结合活性。这些结合活性可以通过 bZip G-box 结合同源二聚体或异源二聚体亚基对 G-box 半位点的亲和力来解释。这些实验产生了一组分类规则，可以预测所有报道的含有共有六聚体核心的植物 G-box 基序的结合活性。含有G-box基序的基因的组织和/或发育特异性表达可以通过G-box蛋白对不同类别的G-box元件的亲和力来调节。
The CACGTG G-box motif is a highly conserved DNA sequence that has been identified in the 5' upstream region of plant genes exhibiting regulation by a variety of environmental signals and physiological cues. Gel mobility shift assays using a panel of G-box oligonucleotides differing in their flanking sequences identified two types of binding activity (A and B) in a cauliflower nuclear extract. Competition gel retardation assays demonstrated that the two types of binding activity were distinct. Type A binding activity interacted with oligonucleotides designated as class I elements, whereas type B binding activity interacted strongly with class II elements and weakly with class I elements. A third class of elements, null elements, did not exhibit any detectable binding under our assay conditions. Gel retardation analysis of nonpalindromic hybrid G-box oligonucleotides indicated that hybrid elements of the same class exhibited binding affinity commensurate with the affinity of the weaker element, hybrid class I/II elements exhibited only type B binding, and hybrid class I/null and class II/null elements did not show any detectable binding activity. These binding activities can be explained by the affinity of bZip G-box binding homo- or heterodimer subunits for G-box half sites. These experiments led to a set of classification rules that can predict the binding activity of all reported plant G-box motifs containing the consensus hexameric core. Tissue- and/or development-specific expression of genes containing G-box motifs may be regulated by the affinity of G-box proteins for the different classes of G-box elements.