Understanding the origins and mechanisms of aryl hydrocarbon receptor promiscuity

了解芳烃受体混杂的起源和机制

• 批准号: 10679532
• 负责人: Mark E Hahn
• 金额: $ 51.1万
• 依托单位: WOODS HOLE OCEANOGRAPHIC INSTITUTION
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-09 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10679532
• 关键词: Address; Agonist; Allosteric Regulation; Amino Acid Sequence; Amino Acids; Animals; Aromatic Hydrocarbons; Aromatic Polycyclic Hydrocarbons; Aryl Hydrocarbon Receptor; Basic Science; Binding; Biological Process; Cell Differentiation process; Chemicals; Chordata; Circadian Rhythms; Dependence; Development; Dietary Phytochemical; Dioxins; Disease; Docking; Embryonic Development; Engineering; Environmental Exposure; Environmental Pollutants; Enzymes; Etiology; Eukaryota; Evolution; Exposure to; Family; Foundations; Genetic; Goals; Helix-Turn-Helix Motifs; Hematopoiesis; Hypoxia Inducible Factor; Immunity; Inflammatory; Invertebrates; Laboratories; Ligand Binding; Ligands; Malignant Neoplasms; Mediating; Modernization; Molecular; Mutate; Mutation; NPAS4 gene; Natural Products; Nuclear Receptors; Organ; Phylogenetic Analysis; Physiological; Physiological Processes; Physiology; Play; Polychlorinated Biphenyls; Process; Property; Proteins; Regulation; Research; Role; Sampling; Sensitivity and Specificity; Signal Transduction; Specificity; Statistical Methods; Structure; Testing; Tetrachlorodibenzodioxin; Time; Toxic effect; Transcriptional Activation; Trees; Tryptophan; Vertebrates; Work; Xenobiotics; anthropogenesis; aryl hydrocarbon receptor ligand; candidate identification; exposed human population; gut microbiome; halogenation; host microbiome; immune function; innovation; insight; member; microbial; microbiome; molecular modeling; receptor; receptor function; reconstruction; response; sensor; single-minded protein; transcription factor

Project Summary/Abstract The aryl hydrocarbon receptor (AHR) is a bHLH-PAS protein that in vertebrate animals is a ligand-activated transcription factor that plays essential roles in the regulation of xenobiotic-metabolizing enzymes and in the mechanisms of toxicity of numerous environmental contaminants, including chlorinated dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), some polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), and some emerging contaminants. The AHR is also involved in a variety of physiological processes including development, hematopoiesis, immunity, host-microbiome interactions, and barrier organ function. In contrast to most ligand-activated transcription factors that have narrow ligand- specificity, the vertebrate AHR is highly promiscuous, recognizing a diverse array of chemicals. In addition to the well-known xenobiotics, AHR ligands include dietary phytochemicals, microbiome-derived microbial metabolites, and endogenous metabolites such as tryptophan catabolites, all of which collectively contribute to the internal chemical exposome. A comprehensive mechanistic understanding of AHR’s role in the response to environmental exposures has been hindered by the complexity of its physiological functions and the bewildering diversity of its ligands. Here, we propose a set of innovative molecular studies to elucidate the sequence-structure-function determinants of AHR ligand-dependence and the origin of its ligand diversity. Evidence suggests that the AHR evolved from a ligand-independent (constitutively active) ancestor. The proposed basic research will experimentally determine the evolutionary trajectory and underlying genetic and structural mechanisms that drove the evolution of AHR ligand-dependence and promiscuity. In Aim 1, we will establish the ligand-specificity of AHRs from present-day species through a systematic experimental assessment of phylogenetically diverse metazoan AHRs, including new invertebrate and early vertebrate AHRs. In Aim 2, we will use ancestral sequence reconstruction (ASR) to “resurrect” ancestral AHR proteins and then determine their ligand-binding sensitivity and specificity, revealing the identities of ancestral and derived ligands. In Aim 3, we will use phylogenetic and protein structural analysis to identify candidate historical amino acid changes that caused the acquisition of ligand-binding and evolution of promiscuity. We will test these hypotheses by engineering ancestral and extant proteins containing these substitutions and experimentally assessing their function. Understanding the ancestral properties of the primordial ligand- activated AHR and the mechanisms that drove the evolution of promiscuity will provide essential new insights into the natural physiological ligands and biological functions of extant AHR, reveal the genetic and structural mechanisms underlying AHR ligand recognition, and elucidate how and why AHR function is disrupted by anthropogenic environmental contaminants.

项目摘要/摘要 芳基烃受体（AHR）是一种BHLH-PAS蛋白，在脊椎动物中是配体激活的 转录因子在调节异生物生物代谢酶以及在 许多环境污染物的毒性机制，包括氯化二恶英，例如 2,3,7,8-四氯二苯甲酸-P-二恶英（TCDD），一些多氯联苯（PCB），多核芳香族 碳氢化合物（PAHS）和一些新兴的污染物。 AHR也参与了各种各样的 物理过程包括发育，造血，免疫学，宿主 - 微生物组相互作用以及 屏障器官功能。与大多数配体的转录因子相比，配体狭窄 脊椎动物AHR的特异性高度混杂，识别出一系列化学物质。此外 著名的异种生物，AHR配体包括饮食植物化学物质，微生物组衍生的微生物 代谢产物和内源代谢产物，例如色氨酸分解代谢物，所有这些都共同有助于 内部化学杂志。对AHR在回应中的作用的全面理解 环境暴露受到其生理功能的复杂性和 令人困惑的配体多样性。在这里，我们提出了一组创新的分子研究，以阐明 序列结构功能确定AHR配体依赖性及其配体多样性的起源。 证据表明，AHR是从独立的（组成型）祖先演变而来的。 拟议的基础研究将通过实验确定进化轨迹和潜在的遗传和 促进了AHR配体依赖性和滥交的结构机制。在AIM 1中，我们将 通过系统的实验建立当今物种的AHR的配体特异性 评估系统发育多样的后生AHR，包括新的无脊椎动物和早期脊椎动物 啊。在AIM 2中，我们将使用祖传序列重建（ASR）来“复活”祖先AHR蛋白 然后确定它们的配体结合敏感性和特异性，揭示了祖先和 派生的配体。在AIM 3中，我们将使用系统发育和蛋白质结构分析来识别候选者 历史氨基酸的变化导致了配体结合和滥交的演变的获取。我们 将通过工程和广泛的蛋白质来检验这些假设，这些蛋白质包含这些替代品和 实验评估其功能。了解原始配体的祖传特性 激活的AHR和推动滥交演变的机制将提供必不可少的新见解 进入额外AHR的天然生理配体和生物学功能，揭示了遗传和结构 AHR配体识别的机制，并阐明了AHR功能如何以及为什么被破坏 人为环境污染物。