DEFINITION OF A MINIMAL DOMAIN OF THE DIOXIN RECEPTOR THAT IS ASSOCIATED WITH HSP90 AND MAINTAINS WILD-TYPE LIGAND-BINDING AFFINITY AND SPECIFICITY
DEFINITION OF A MINIMAL DOMAIN OF THE DIOXIN RECEPTOR THAT IS ASSOCIATED WITH HSP90 AND MAINTAINS WILD-TYPE LIGAND-BINDING AFFINITY AND SPECIFICITY
复制标题
DOI：
10.1074/jbc.270.42.25291
复制
发表时间：
1995-10-20
影响因子：
4.8
通讯作者：
WHITELAW, ML
中科院分区：
文献类型：
--
作者：
COUMAILLEAU, P;POELLINGER, L;WHITELAW, ML
二恶英受体是已知结合平面多环配体的细胞质碱性螺旋-环-螺旋/Per-Arnt-Sim同源（bHLH/PAS）蛋白，所述平面多环配体包括多环芳烃、苯并呋喃酮、杂环胺和卤代芳烃，例如二恶英。配体诱导的二恶英受体活化启动了一个过程，由此受体转化为具有特定bHLH/PAS伴侣蛋白Arnt的核转录因子复合物。与糖皮质激素受体类似，发现潜在的二恶英受体与分子伴侣hsp 90相关。我们已经定义和分离的二恶英受体的最小配体结合域从中央PAS区域，包括氨基酸230至421，并发现这个域在体外与热休克蛋白90相互作用。在麦胚裂解物或细菌中表达最小配体结合结构域，这些系统含有不能与糖皮质激素或二恶英受体相互作用的hsp 90同系物，导致该最小230至421片段的非配体结合形式。重要的是，二恶英的最小配体结合结构域的亲和力是相似的，在全长二恶英受体的固有的亲和力，和配置文件的配体结构，特异性结合的最小配体结合结构域被发现是保守的这个域和天然受体之间。这些实验表明，最小的配体结合结构域保持了全长受体所表现出的配体结合的定量和定性方面，这意味着中央配体结合口袋可能存在以容纳所有类别的特定二恶英受体配体，并且该口袋是严重依赖于热休克蛋白90的配体结合构象。
The dioxin receptor is a cytoplasmic basic helix-loop-helix/Per-Arnt-Sim homology (bHLH/PAS) protein known to bind planar polycyclic ligands including polycyclic aromatic hydrocarbons, benzoflavones, heterocyclic amines, and halogenated aromatic hydrocarbons, e.g. dioxins. Ligand-induced activation of the dioxin receptor initiates a process whereby the receptor is transformed into a nuclear transcription factor complex with a specific bHLH/PAS partner protein, Arnt. In analogy to the glucocorticoid receptor, the latent dioxin receptor is found associated with the molecular chaperone hsp90. We have defined and isolated a minimal ligand binding domain of the dioxin receptor from the central PAS region, comprising of amino acids 230 to 421, and found this domain to interact with hsp90 in vitro. Expression of the minimal ligand binding domain in wheat germ lysates or bacteria, systems which harbor hsp90 homologs unable to interact with the glucocorticoid or dioxin receptors, resulted in non-ligand binding forms of this minimal 230 to 421 fragment. Importantly, affinity of the minimal ligand binding domain for dioxin was similar to the affinity inherent in the full-length dioxin receptor, and a profile of ligand structures which specifically bound the minimal ligand binding domain was found to be conserved between this domain and the native receptor. These experiments show that the minimal ligand binding domain maintains the quantitative and qualitative aspects of ligand binding exhibited by the full-length receptor, implying that the central ligand binding pocket may exist to accommodate all classes of specific dioxin receptor ligands, and that this pocket is critically dependent upon hsp90 for its ligand binding conformation.