THE FUNCTION AND STRUCTURE OF THE METAL COORDINATION SITES WITHIN THE GLUCOCORTICOID RECEPTOR DNA-BINDING DOMAIN
THE FUNCTION AND STRUCTURE OF THE METAL COORDINATION SITES WITHIN THE GLUCOCORTICOID RECEPTOR DNA-BINDING DOMAIN
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DOI：
10.1038/334543a0
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发表时间：
1988-08-11
期刊：
影响因子：
64.8
通讯作者：
YAMAMOTO, KR
中科院分区：
文献类型：
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作者：
FREEDMAN, LP;LUISI, BF;YAMAMOTO, KR
糖皮质激素受体通过与称为糖皮质激素反应元件 (GREs1-5) 的特定 DNA 序列结合来增强或抑制转录。对克隆糖皮质激素受体 6-8 的研究表明，该蛋白质被组织为功能域，这种排列在类固醇受体家族成员中似乎很常见 9。该基因中心附近的一个片段指定了体外 DNA 结合活性，并包含两个类似于非洲爪蟾转录因子 III A (TFIIIA)10 中发现的“锌指”的序列基序。此类序列基序已在多种生物体的核酸结合蛋白中得到鉴定11-13。类固醇受体蛋白指被认为通过两对保守的半胱氨酸残基结合锌7,14,15。我们在这里报道了一种相对分子质量为 19,000 (Mr= 19K) 的蛋白质，包含糖皮质激素受体的 DNA 结合结构域，该受体已在大肠杆菌中过表达并纯化至同质性，可逆地连接两个 Zn(II) 或 Cd(II) 离子。我们证明，特定的 DNA 结合和正确折叠需要金属离子。使用 EXAFS（扩展 X 射线吸收精细结构）和可见光光谱，我们发现每个 Zn 原子由四个半胱氨酸以四面体排列进行配位。
The glucocorticoid receptor enhances or represses transcription by binding to specific DNA sequences termed glucocorticoid response elements, or GREs1–5. Studies of cloned glucocorticoid receptors6–8reveal that the protein is organized as functional domains, in an arrangement that appears to be common among members of the steroid receptor family9. A segment near the centre of the gene specifies DNA binding activityin vitroand contains two sequence motifs similar to 'zinc fingers' found inXenopustranscription factor III A (TFIIIA)10. Such sequence motifs have been identified in nucleic acid binding proteins from a wide range of organisms11–13. Steroid receptor protein fingers are proposed to bind zinc through two pairs of conserved cysteine residues7,14,15.We report here that a protein of relative molecular mass 19,000 (Mr= 19K) encompassing the DNA-binding domain of the glucocorticoid receptor that has been overexpressed inEscherichia coliand purified to homogeneity reversibly ligates two Zn(II) or Cd(II) ions. We show that metal ions are required for specific DNA binding and proper folding. Using EXAFS (extended X-ray absorption fine structure) and visible light spectroscopies, we find that each Zn atom is coordinated in a tetrahedral arrangement by four cysteines.