Detection of the TCDD binding-fingerprint within the Ah receptor ligand binding domain by structurally driven mutagenesis and functional analysis.
Detection of the TCDD binding-fingerprint within the Ah receptor ligand binding domain by structurally driven mutagenesis and functional analysis.
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DOI：
10.1021/bi900259z
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发表时间：
2009-06-30
期刊：
影响因子：
2.9
通讯作者：
Denison, Michael S.
中科院分区：
文献类型：
--
作者：
Pandini, Alessandro;Soshilov, Anatoly A.;Song, Yujuan;Zhao, Jing;Bonati, Laura;Denison, Michael S.
芳烃受体（AhR）是一种配体依赖性的、碱性螺旋-环-螺旋Per-Arnt-Sim（PAS）转录因子，其可以结合并被结构上不同的化学物质激活，包括有毒环境污染物2，3，7，8-四氯二苯并-对-二恶英（TCDD）。我们以前的小鼠AhR（mAhR）PAS B配体结合结构域的三维同源模型允许识别的结合位点和实验验证。我们通过对另外六种高亲和力哺乳动物AhRs的配体结合结构域进行比较结构建模研究，扩展了这一分析。这些结果，再加上定点诱变和AhR功能分析，允许检测的“TCDD结合指纹”的保守残基内的配体结合腔必需的高亲和力TCDD结合和TCDD依赖性AhR转化DNA结合。所选残基的重要作用进行了进一步评估，使用TCDD与野生型和突变型mAhRs的分子对接模拟。两者合计，我们的研究结果大大提高了我们的理解TCDD结合的分子决定因素，并为今后的研究提供了基础，旨在合理化所观察到的物种差异AhR对TCDD的敏感性，并了解AhR配体结构的巨大多样性的机制基础。
The aryl hydrocarbon receptor (AhR) is a ligand-dependent, basic helix–loop–helix Per-Arnt-Sim (PAS)-containing transcription factor that can bind and be activated by structurally diverse chemicals, including the toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Our previous three-dimensional homology model of the mouse AhR (mAhR) PAS B ligand binding domain allowed identification of the binding site and its experimental validation. We have extended this analysis by conducting comparative structural modeling studies of the ligand binding domains of six additional high-affinity mammalian AhRs. These results, coupled with site-directed mutagenesis and AhR functional analysis, have allowed detection of the “TCDD binding-fingerprint” of conserved residues within the ligand binding cavity necessary for high-affinity TCDD binding and TCDD-dependent AhR transformation DNA binding. The essential role of selected residues was further evaluated using molecular docking simulations of TCDD with both wild-type and mutant mAhRs. Taken together, our results dramatically improve our understanding of the molecular determinants of TCDD binding and provide a basis for future studies directed toward rationalizing the observed species differences in AhR sensitivity to TCDD and understanding the mechanistic basis for the dramatic diversity in AhR ligand structure.
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