NUCLEOTIDES FLANKING A CONSERVED TAAT CORE DICTATE THE DNA-BINDING SPECIFICITY OF 3 MURINE HOMEODOMAIN PROTEINS
NUCLEOTIDES FLANKING A CONSERVED TAAT CORE DICTATE THE DNA-BINDING SPECIFICITY OF 3 MURINE HOMEODOMAIN PROTEINS
复制标题
DOI：
10.1128/mcb.13.4.2354
复制
发表时间：
1993-04-01
影响因子：
5.3
通讯作者：
ABATE, C
中科院分区：
文献类型：
--
作者：
CATRON, KM;ILER, N;ABATE, C
小鼠同源盒基因通过控制发育过程中的基因表达，在指导胚胎发育过程中发挥着重要作用。同源框编码一个DNA结合域(同源结构域)，该结构域可能介导同源结构域蛋白与靶基因控制区中特定DNA位点的相互作用。然而，这些选择性DNA-蛋白质相互作用的基础还没有很好地定义。在这份报告中，我们表征了三种小鼠同源域蛋白，Hox 7.1，Hox 1.5和EN-1的DNA结合特异性。我们使用随机寡核苷酸选择策略确定了每种蛋白质的最佳DNA结合位点。对所选结合位点的序列进行比较，预测出包含(C/G)TAATTG基序的共同共识位点。TAAT核心对于DNA结合活性是必不可少的，而该核心两侧的核苷酸指示了结合特异性。虽然Tat核心5‘侧翼核苷酸的变化对所有三种蛋白质的结合活性都有轻微的影响，但核心3’端核苷酸的扰动将Hox 1.5与Hox 7.1和EN-1的结合特异性区分开来。这些结合活性的差异反映了蛋白质-DNA复合体的解离速率的差异，而不是平衡常数的差异。在体外观察到的DNA结合特异性的差异可能有助于同源结构域蛋白与靶基因控制区潜在结合部位的选择性相互作用。
Murine homeobox genes play a fundamental role in directing embryogenesis by controlling gene expression during development. The homeobox encodes a DNA binding domain (the homeodomain) which presumably mediates interactions of homeodomain proteins with specific DNA sites in the control regions of target genes. However, the bases for these selective DNA-protein interactions are not well defined. In this report, we have characterized the DNA binding specificities of three murine homeodomain proteins, Hox 7.1, Hox 1.5, and En-1. We have identified optimal DNA binding sites for each of these proteins by using a random oligonucleotide selection strategy. Comparison of the sequences of the selected binding sites predicted a common consensus site that contained the motif (C/G)TAATTG. The TAAT core was essential for DNA binding activity, and the nucleotides flanking this core directed binding specificity. Whereas variations in the nucleotides flanking the 5' side of the TAAT core produced modest alterations in binding activity for all three proteins, perturbations of the nucleotides directly 3' of the core distinguished the binding specificity of Hox 1.5 from those of Hox 7.1 and En-1. These differences in binding activity reflected differences in the dissociation rates rather than the equilibrium constants of the protein-DNA complexes. Differences in DNA binding specificities observed in vitro may contribute to selective interactions of homeodomain proteins with potential binding sites in the control regions of target genes.