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Tomkiewicz C, Coumoul X, Nioche P, Barouki R, Blanc EB. Costs of molecular adaptation to the chemical exposome: a focus on xenobiotic metabolism pathways. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220510. [PMID: 38310928 PMCID: PMC10838638 DOI: 10.1098/rstb.2022.0510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 12/04/2023] [Indexed: 02/06/2024] Open
Abstract
Organisms adapt to their environment through different pathways. In vertebrates, xenobiotics are detected, metabolized and eliminated through the inducible xenobiotic-metabolizing pathways (XMP) which can also generate reactive toxic intermediates. In this review, we will discuss the impacts of the chemical exposome complexity on the balance between detoxication and side effects. There is a large discrepancy between the limited number of proteins involved in these pathways (few dozens) and the diversity and complexity of the chemical exposome (tens of thousands of chemicals). Several XMP proteins have a low specificity which allows them to bind and/or metabolize a large number of chemicals. This leads to undesired consequences, such as cross-inhibition, inefficient metabolism, release of toxic intermediates, etc. Furthermore, several XMP proteins have endogenous functions that may be disrupted upon exposure to exogenous chemicals. The gut microbiome produces a very large number of metabolites that enter the body and are part of the chemical exposome. It can metabolize xenobiotics and either eliminate them or lead to toxic derivatives. The complex interactions between chemicals of different origins will be illustrated by the diverse roles of the aryl hydrocarbon receptor which binds and transduces the signals of a large number of xenobiotics, microbiome metabolites, dietary chemicals and endogenous compounds. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.
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Affiliation(s)
| | - Xavier Coumoul
- Université Paris Cité, Inserm unit UMRS 1124, 75006 Paris, France
| | - Pierre Nioche
- Université Paris Cité, Inserm unit UMRS 1124, 75006 Paris, France
| | - Robert Barouki
- Université Paris Cité, Inserm unit UMRS 1124, 75006 Paris, France
- Hôpital Necker Enfants malades, AP-HP, 75006 Paris, France
| | - Etienne B. Blanc
- Université Paris Cité, Inserm unit UMRS 1124, 75006 Paris, France
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Kwong HS, Paloni M, Grandvuillemin L, Sirounian S, Ancelin A, Lai-Kee-Him J, Grimaldi M, Carivenc C, Lancey C, Ragan TJ, Hesketh EL, Balaguer P, Barducci A, Gruszczyk J, Bourguet W. Structural Insights into the Activation of Human Aryl Hydrocarbon Receptor by the Environmental Contaminant Benzo[a]pyrene and Structurally Related Compounds. J Mol Biol 2024; 436:168411. [PMID: 38135181 DOI: 10.1016/j.jmb.2023.168411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/10/2023] [Accepted: 12/18/2023] [Indexed: 12/24/2023]
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor belonging to the bHLH/PAS protein family and responding to hundreds of natural and chemical substances. It is primarily involved in the defense against chemical insults and bacterial infections or in the adaptive immune response, but also in the development of pathological conditions ranging from inflammatory to neoplastic disorders. Despite its prominent roles in many (patho)physiological processes, the lack of high-resolution structural data has precluded for thirty years an in-depth understanding of the structural mechanisms underlying ligand-binding specificity, promiscuity and activation of AHR. We recently reported a cryogenic electron microscopy (cryo-EM) structure of human AHR bound to the natural ligand indirubin, the chaperone Hsp90 and the co-chaperone XAP2 that provided the first experimental visualization of its ligand-binding PAS-B domain. Here, we report a 2.75 Å resolution structure of the AHR complex bound to the environmental pollutant benzo[a]pyrene (B[a]P). The structure substantiates the existence of a bipartite PAS-B ligand-binding pocket with a geometrically constrained primary binding site controlling ligand binding specificity and affinity, and a secondary binding site contributing to the binding promiscuity of AHR. We also report a docking study of B[a]P congeners that validates the B[a]P-bound PAS-B structure as a suitable model for accurate computational ligand binding assessment. Finally, comparison of our agonist-bound complex with the recently reported structures of mouse and fruit fly AHR PAS-B in different activation states suggests a ligand-induced loop conformational change potentially involved in the regulation of AHR function.
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Affiliation(s)
- Hok-Sau Kwong
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Matteo Paloni
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Loïc Grandvuillemin
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Savannah Sirounian
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Aurélie Ancelin
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Josephine Lai-Kee-Him
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Marina Grimaldi
- IRCM (Institut de Recherche en Cancérologie de Montpellier), Univ Montpellier, Inserm, ICM, Montpellier, France
| | - Coralie Carivenc
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Claudia Lancey
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester LE1 7HB, UK
| | - Timothy J Ragan
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester LE1 7HB, UK
| | - Emma L Hesketh
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester LE1 7HB, UK
| | - Patrick Balaguer
- IRCM (Institut de Recherche en Cancérologie de Montpellier), Univ Montpellier, Inserm, ICM, Montpellier, France
| | - Alessandro Barducci
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France
| | - Jakub Gruszczyk
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France.
| | - William Bourguet
- CBS (Centre de Biologie Structurale), Univ Montpellier, CNRS, Inserm, Montpellier, France.
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