Molecular Characterization of Mammalian bHLH-PAS Transcription Factors

 描述(申请人提供)：基本的Helix-Loop-Helix-Per/Arnt/Sim(bHLH-PAS)家族是哺乳动物中的一组主要转录因子。在这个家族中，功能异二聚体通过一个组织限制性亚基形成，如低氧诱导因子(HIF)、神经元PAS蛋白或芳香烃受体(AHR)，以及一个共同的二聚化亚基，如芳烃受体核转运体(ARNT)。家族成员包含串联PAS结构域和DNA结合域。PAS结构域有可能作为分子传感器并传递信号来调节这些转录因子的活性。该家族中的HIF亚群调节在人类肿瘤的启动、进展、侵袭和转移中至关重要的遗传程序。几种NPAS蛋白在基因上与人类神经精神疾病有关。AHR识别并响应一系列外源分子，并驱动解毒所需的基因程序。我们目前对这些杂二聚体的结构、它们的配体结合口袋以及配体反应活性的了解是有限的。因此，我们已经开始对包括结合DNA和小分子配体在内的络合物中的几种bHLH-PAS杂二聚体进行详细的结构研究。我们提出的结构特征将与化学生物学和基于细胞的研究相补充，以加深我们对该家族结构-功能关系的理解。这项建议的总体目标包括通过X射线结晶学表征不同的bHLH-PAS异源二聚体，询问其配体结合口袋的位置和组成，识别新的工具化合物，以及研究配体和疾病相关突变如何通过蛋白质结构表现其作用。

 DESCRIPTION (provided by applicant): The basic Helix-Loop-Helix-Per/Arnt/Sim (bHLH-PAS) family is a major group of transcription factors in mammals. Functional heterodimers in this family form via a tissue-restricted subunit, such as the hypoxia- inducible factors (HIFs), neuronal PAS (NPAS) proteins, or aryl hydrocarbon receptor (AHR), and a common dimerization subunit, such as aryl hydrocarbon receptor nuclear translocator (ARNT). Family members contain tandem PAS domains and a DNA-binding domain. PAS domains have the potential to act as molecular sensors and transmit signals to regulate the activities of these transcription factors. The HIF subgroup within the family regulates genetic programs critical in human tumor initiation, progression, invasion and metastasis. Several NPAS proteins have been genetically linked to human neuropsychiatric disorders. AHR recognizes and responds to a spectrum of xenobiotic molecules and drives gene programs necessary for detoxification. Our current knowledge about the architectures of these heterodimers, their ligand-binding pockets, and ligand- responsive activities is limited. Therefore, we have begun to conduct detailed structural investigations into several bHLH-PAS heterodimers in complexes that include bound DNA and small-molecule ligands. Our proposed structural characterizations will be complemented with chemical biology and cell-based studies to deepen our understanding of structure-function relationships in this family. The overall goals of this proposal include characterizing distinct bHLH-PAS heterodimers by X-ray crystallography, interrogating the location and composition of their ligand-binding pockets, identifying new tool compounds, and examining how ligands and disease-linked mutations manifest their actions through protein architectures.