Molecular Characterization of Mammalian bHLH-PAS Transcription Factors

 描述（由申请人提供）：基本螺旋-环-螺旋-Per/Arnt/Sim（bHLH-PAS）家族是哺乳动物中的一组主要转录因子。该家族中的功能性异二聚体通过组织限制性亚基（例如缺氧诱导因子（HIF）、神经元PAS（NPAS）蛋白或芳烃受体（AHR））和常见的二聚化亚基（例如芳烃受体核转运子（ARNT））形成。家族成员包含串联PAS结构域和DNA结合结构域。PAS结构域有潜力充当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亚组调节在人类肿瘤发生、进展、侵袭和转移中至关重要的遗传程序。几种NPAS蛋白质与人类神经精神疾病有遗传联系。AHR识别并响应一系列异生物质分子，并驱动解毒所需的基因程序。我们目前对这些异二聚体的结构、它们的配体结合口袋和配体响应活性的了解是有限的。因此，我们已经开始进行详细的结构调查几个bHLH-PAS异二聚体的复合物，包括结合的DNA和小分子配体。我们提出的结构表征将与化学生物学和基于细胞的研究相结合，以加深我们对该家族结构-功能关系的理解。该提案的总体目标包括通过X射线晶体学表征不同的bHLH-PAS异源二聚体，询问其配体结合口袋的位置和组成，鉴定新的工具化合物，并研究配体和疾病相关突变如何通过蛋白质结构表现出它们的作用。

 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.