Understanding the origins and mechanisms of aryl hydrocarbon receptor promiscuity

了解芳烃受体混杂的起源和机制

基本信息

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
项目类别：
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

项目摘要

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.

项目概要/摘要芳烃受体 (AHR) 是一种 bHLH-PAS 蛋白，在脊椎动物中是配体激活的转录因子，在外源代谢酶的调节和许多环境污染物的毒性机制，包括氯化二恶英，例如 2,3,7,8-四氯二苯并-对二恶英 (TCDD)、某些多氯联苯 (PCB)、多核芳香族化合物 AHR 还涉及多种碳氢化合物 (PAH) 和一些新兴污染物。生理过程，包括发育、造血、免疫、宿主-微生物组相互作用以及与大多数具有狭窄配体的配体激活转录因子相反。除了特异性之外，脊椎动物 AHR 还具有高度混杂性，可以识别多种化学物质。众所周知的异生素，AHR配体包括膳食植物化学物质、微生物组衍生的微生物代谢物和内源性代谢物，如色氨酸分解代谢物，所有这些共同促进内部化学暴露组对 AHR 在响应中的作用的全面机制理解。其生理功能和环境的复杂性阻碍了其暴露于环境在这里，我们提出了一系列创新的分子研究来阐明其配体的多样性。 AHR 配体依赖性的序列-结构-功能决定因素及其配体多样性的起源。有证据表明，AHR 是从配体独立（组成型活性）祖先进化而来的。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在目标 1 中，我们将研究驱动 AHR 配体依赖性和混杂性进化的结构机制。通过系统实验确定当今物种 AHR 的配体特异性系统发育多样性后生动物 AHR 的评估，包括新的无脊椎动物和早期脊椎动物在目标 2 中，我们将使用祖先序列重建 (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，揭示祖先和祖先的身份在目标 3 中，我们将使用系统发育和蛋白质结构分析来识别候选配体。导致配体结合的获得和混杂进化的历史氨基酸变化。将通过工程化含有这些取代的祖先和现存蛋白质来测试这些假设通过实验评估它们的功能。激活的 AHR 和推动乱交演变的机制将提供重要的新见解研究现存AHR的天然生理配体和生物功能，揭示其遗传和结构 AHR 配体识别的机制，并阐明 AHR 功能如何以及为何被破坏人为环境污染物。