1
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Kottur J, Malik R, Aggarwal AK. Nucleic acid mediated activation of a short prokaryotic Argonaute immune system. Nat Commun 2024; 15:4852. [PMID: 38844755 PMCID: PMC11156904 DOI: 10.1038/s41467-024-49271-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 05/30/2024] [Indexed: 06/09/2024] Open
Abstract
A short prokaryotic Argonaute (pAgo) TIR-APAZ (SPARTA) defense system, activated by invading DNA to unleash its TIR domain for NAD(P)+ hydrolysis, was recently identified in bacteria. We report the crystal structure of SPARTA heterodimer in the absence of guide-RNA/target-ssDNA (2.66 Å) and a cryo-EM structure of the SPARTA oligomer (tetramer of heterodimers) bound to guide-RNA/target-ssDNA at nominal 3.15-3.35 Å resolution. The crystal structure provides a high-resolution view of SPARTA, revealing the APAZ domain as equivalent to the N, L1, and L2 regions of long pAgos and the MID domain containing a unique insertion (insert57). Cryo-EM structure reveals regions of the PIWI (loop10-9) and APAZ (helix αN) domains that reconfigure for nucleic-acid binding and decrypts regions/residues that reorganize to expose a positively charged pocket for higher-order assembly. The TIR domains amass in a parallel-strands arrangement for catalysis. We visualize SPARTA before and after RNA/ssDNA binding and uncover the basis of its active assembly leading to abortive infection.
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Affiliation(s)
- Jithesh Kottur
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
- Department of Antiviral Drug Research, Institute of Advanced Virology, Thiruvananthapuram, Kerala, 695317, India.
| | - Radhika Malik
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
| | - Aneel K Aggarwal
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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2
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Carabias A, Camara-Wilpert S, Mestre MR, Lopéz-Méndez B, Hendriks IA, Zhao R, Pape T, Fuglsang A, Luk SHC, Nielsen ML, Pinilla-Redondo R, Montoya G. Retron-Eco1 assembles NAD +-hydrolyzing filaments that provide immunity against bacteriophages. Mol Cell 2024; 84:2185-2202.e12. [PMID: 38788717 DOI: 10.1016/j.molcel.2024.05.001] [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: 09/26/2023] [Revised: 03/15/2024] [Accepted: 05/01/2024] [Indexed: 05/26/2024]
Abstract
Retrons are toxin-antitoxin systems protecting bacteria against bacteriophages via abortive infection. The Retron-Eco1 antitoxin is formed by a reverse transcriptase (RT) and a non-coding RNA (ncRNA)/multi-copy single-stranded DNA (msDNA) hybrid that neutralizes an uncharacterized toxic effector. Yet, the molecular mechanisms underlying phage defense remain unknown. Here, we show that the N-glycosidase effector, which belongs to the STIR superfamily, hydrolyzes NAD+ during infection. Cryoelectron microscopy (cryo-EM) analysis shows that the msDNA stabilizes a filament that cages the effector in a low-activity state in which ADPr, a NAD+ hydrolysis product, is covalently linked to the catalytic E106 residue. Mutations shortening the msDNA induce filament disassembly and the effector's toxicity, underscoring the msDNA role in immunity. Furthermore, we discovered a phage-encoded Retron-Eco1 inhibitor (U56) that binds ADPr, highlighting the intricate interplay between retron systems and phage evolution. Our work outlines the structural basis of Retron-Eco1 defense, uncovering ADPr's pivotal role in immunity.
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Affiliation(s)
- Arturo Carabias
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| | - Sarah Camara-Wilpert
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Mario Rodríguez Mestre
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Blanca Lopéz-Méndez
- Protein Purification and Characterization Facility, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Ivo A Hendriks
- Proteomics Department, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Ruiliang Zhao
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Tillmann Pape
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; Core Facility for Integrated Microscopy (CFIM), Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Anders Fuglsang
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Sean Hoi-Ching Luk
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Michael L Nielsen
- Proteomics Department, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Rafael Pinilla-Redondo
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark.
| | - Guillermo Montoya
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
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3
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Marques-da-Silva C, Schmidt-Silva C, Kurup SP. Hepatocytes and the art of killing Plasmodium softly. Trends Parasitol 2024; 40:466-476. [PMID: 38714463 PMCID: PMC11156546 DOI: 10.1016/j.pt.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/05/2024] [Accepted: 04/07/2024] [Indexed: 05/09/2024]
Abstract
The Plasmodium parasites that cause malaria undergo asymptomatic development in the parenchymal cells of the liver, the hepatocytes, prior to infecting erythrocytes and causing clinical disease. Traditionally, hepatocytes have been perceived as passive bystanders that allow hepatotropic pathogens such as Plasmodium to develop relatively unchallenged. However, now there is emerging evidence suggesting that hepatocytes can mount robust cell-autonomous immune responses that target Plasmodium, limiting its progression to the blood and reducing the incidence and severity of clinical malaria. Here we discuss our current understanding of hepatocyte cell-intrinsic immune responses that target Plasmodium and how these pathways impact malaria.
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Affiliation(s)
- Camila Marques-da-Silva
- Department of Cellular Biology, University of Georgia, Athens, GA, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
| | - Clyde Schmidt-Silva
- Department of Cellular Biology, University of Georgia, Athens, GA, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
| | - Samarchith P Kurup
- Department of Cellular Biology, University of Georgia, Athens, GA, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA.
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4
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Bonhomme D, Poirier EZ. Early signaling pathways in virus-infected cells. Curr Opin Virol 2024; 66:101411. [PMID: 38718574 DOI: 10.1016/j.coviro.2024.101411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 06/07/2024]
Abstract
Virus infection activates specific pattern recognition receptors and immune signal transduction, resulting in pro-inflammatory cytokine production and activation of innate immunity. We describe here the molecular organization of early signaling pathways downstream of viral recognition, including conformational changes, post-translational modifications, formation of oligomers, and generation of small-molecule second messengers. Such molecular organization allows tight regulation of immune signal transduction, characterized by swift but transient responses, nonlinearity, and signal amplification. Pathologies of early immune signaling caused by genomic mutations illustrate the fine regulation of the immune transduction cascade.
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Affiliation(s)
- Delphine Bonhomme
- Institut Curie, Stem Cell Immunity Lab, PSL Research University, INSERM U932, Paris, France
| | - Enzo Z Poirier
- Institut Curie, Stem Cell Immunity Lab, PSL Research University, INSERM U932, Paris, France.
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5
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Hoogstraten CA, Schirris TJJ, Russel FGM. Unlocking mitochondrial drug targets: The importance of mitochondrial transport proteins. Acta Physiol (Oxf) 2024; 240:e14150. [PMID: 38666512 DOI: 10.1111/apha.14150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 03/02/2024] [Accepted: 04/12/2024] [Indexed: 05/12/2024]
Abstract
A disturbed mitochondrial function contributes to the pathology of many common diseases. These organelles are therefore important therapeutic targets. On the contrary, many adverse effects of drugs can be explained by a mitochondrial off-target effect, in particular, due to an interaction with carrier proteins in the inner membrane. Yet this class of transport proteins remains underappreciated and understudied. The aim of this review is to provide a deeper understanding of the role of mitochondrial carriers in health and disease and their significance as drug targets. We present literature-based evidence that mitochondrial carrier proteins are associated with prevalent diseases and emphasize their potential as drug (off-)target sites by summarizing known mitochondrial drug-transporter interactions. Studying these carriers will enhance our knowledge of mitochondrial drug on- and off-targets and provide opportunities to further improve the efficacy and safety of drugs.
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Affiliation(s)
- Charlotte A Hoogstraten
- Department of Pharmacy, Division of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, the Netherlands
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Tom J J Schirris
- Department of Pharmacy, Division of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, the Netherlands
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Frans G M Russel
- Department of Pharmacy, Division of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, the Netherlands
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
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6
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Blumenstiel JP. From the cauldron of conflict: Endogenous gene regulation by piRNA and other modes of adaptation enabled by selfish transposable elements. Semin Cell Dev Biol 2024; 164:1-12. [PMID: 38823219 DOI: 10.1016/j.semcdb.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 04/28/2024] [Accepted: 05/06/2024] [Indexed: 06/03/2024]
Abstract
Transposable elements (TEs) provide a prime example of genetic conflict because they can proliferate in genomes and populations even if they harm the host. However, numerous studies have shown that TEs, though typically harmful, can also provide fuel for adaptation. This is because they code functional sequences that can be useful for the host in which they reside. In this review, I summarize the "how" and "why" of adaptation enabled by the genetic conflict between TEs and hosts. In addition, focusing on mechanisms of TE control by small piwi-interacting RNAs (piRNAs), I highlight an indirect form of adaptation enabled by conflict. In this case, mechanisms of host defense that regulate TEs have been redeployed for endogenous gene regulation. I propose that the genetic conflict released by meiosis in early eukaryotes may have been important because, among other reasons, it spurred evolutionary innovation on multiple interwoven trajectories - on the part of hosts and also embedded genetic parasites. This form of evolution may function as a complexity generating engine that was a critical player in eukaryotic evolution.
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Affiliation(s)
- Justin P Blumenstiel
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, United States.
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7
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Huang J, Zhu K, Gao Y, Ye F, Li Z, Ge Y, Liu S, Yang J, Gao A. Molecular basis of bacterial DSR2 anti-phage defense and viral immune evasion. Nat Commun 2024; 15:3954. [PMID: 38729958 PMCID: PMC11087589 DOI: 10.1038/s41467-024-48291-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 04/25/2024] [Indexed: 05/12/2024] Open
Abstract
Defense-associated sirtuin 2 (DSR2) systems are widely distributed across prokaryotic genomes, providing robust protection against phage infection. DSR2 recognizes phage tail tube proteins and induces abortive infection by depleting intracellular NAD+, a process that is counteracted by another phage-encoded protein, DSR Anti Defense 1 (DSAD1). Here, we present cryo-EM structures of Bacillus subtilis DSR2 in its apo, Tube-bound, and DSAD1-bound states. DSR2 assembles into an elongated tetramer, with four NADase catalytic modules clustered in the center and the regulatory-sensing modules distributed at four distal corners. Interestingly, monomeric Tube protein, rather than its oligomeric states, docks at each corner of the DSR2 tetramer to form a 4:4 DSR2-Tube assembly, which is essential for DSR2 NADase activity. DSAD1 competes with Tube for binding to DSR2 by occupying an overlapping region, thereby inhibiting DSR2 immunity. Thus, our results provide important insights into the assembly, activation and inhibition of the DSR2 anti-phage defense system.
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Affiliation(s)
- Jiafeng Huang
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Keli Zhu
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Yina Gao
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Feng Ye
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Zhaolong Li
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yao Ge
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Songqing Liu
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jing Yang
- Department of Neurology, Aerospace Center Hospital, Peking University Aerospace School of Clinical Medicine, Beijing, 100049, China.
| | - Ang Gao
- Key Laboratory of Molecular Medicine and Biotherapy, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
- Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China.
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8
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Imler JL, Cai H, Meignin C, Martins N. Evolutionary immunology to explore original antiviral strategies. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230068. [PMID: 38497262 PMCID: PMC10945398 DOI: 10.1098/rstb.2023.0068] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/25/2023] [Indexed: 03/19/2024] Open
Abstract
Over the past 25 years, the field of evolutionary developmental biology (evo-devo) has used genomics and genetics to gain insight on the developmental mechanisms underlying the evolution of morphological diversity of animals. Evo-devo exploits the key insight that conserved toolkits of development (e.g. Hox genes) are used in animals to produce genetic novelties that provide adaptation to a new environment. Like development, immunity is forged by interactions with the environment, namely the microbial world. Yet, when it comes to the study of immune defence mechanisms in invertebrates, interest primarily focuses on evolutionarily conserved molecules also present in humans. Here, focusing on antiviral immunity, we argue that immune genes not conserved in humans represent an unexplored resource for the discovery of new antiviral strategies. We review recent findings on the cGAS-STING pathway and explain how cyclic dinucleotides produced by cGAS-like receptors may be used to investigate the portfolio of antiviral genes in a broad range of species. This will set the stage for evo-immuno approaches, exploiting the investment in antiviral defences made by metazoans over hundreds of millions of years of evolution. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.
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Affiliation(s)
- Jean-Luc Imler
- Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, CNRS UPR9022, Strasbourg 67070, France
- Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, People's Republic of China
| | - Hua Cai
- Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, People's Republic of China
| | - Carine Meignin
- Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, CNRS UPR9022, Strasbourg 67070, France
| | - Nelson Martins
- Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, CNRS UPR9022, Strasbourg 67070, France
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9
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Embry A, Baggett NS, Heisler DB, White A, de Jong MF, Kocsis BL, Tomchick DR, Alto NM, Gammon DB. Exploiting bacterial effector proteins to uncover evolutionarily conserved antiviral host machinery. PLoS Pathog 2024; 20:e1012010. [PMID: 38753575 PMCID: PMC11098378 DOI: 10.1371/journal.ppat.1012010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/11/2024] [Indexed: 05/18/2024] Open
Abstract
Arboviruses are a diverse group of insect-transmitted pathogens that pose global public health challenges. Identifying evolutionarily conserved host factors that combat arbovirus replication in disparate eukaryotic hosts is important as they may tip the balance between productive and abortive viral replication, and thus determine virus host range. Here, we exploit naturally abortive arbovirus infections that we identified in lepidopteran cells and use bacterial effector proteins to uncover host factors restricting arbovirus replication. Bacterial effectors are proteins secreted by pathogenic bacteria into eukaryotic hosts cells that can inhibit antimicrobial defenses. Since bacteria and viruses can encounter common host defenses, we hypothesized that some bacterial effectors may inhibit host factors that restrict arbovirus replication in lepidopteran cells. Thus, we used bacterial effectors as molecular tools to identify host factors that restrict four distinct arboviruses in lepidopteran cells. By screening 210 effectors encoded by seven different bacterial pathogens, we identify several effectors that individually rescue the replication of all four arboviruses. We show that these effectors encode diverse enzymatic activities that are required to break arbovirus restriction. We further characterize Shigella flexneri-encoded IpaH4 as an E3 ubiquitin ligase that directly ubiquitinates two evolutionarily conserved proteins, SHOC2 and PSMC1, promoting their degradation in insect and human cells. We show that depletion of either SHOC2 or PSMC1 in insect or human cells promotes arbovirus replication, indicating that these are ancient virus restriction factors conserved across invertebrate and vertebrate hosts. Collectively, our study reveals a novel pathogen-guided approach to identify conserved antimicrobial machinery, new effector functions, and conserved roles for SHOC2 and PSMC1 in virus restriction.
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Affiliation(s)
- Aaron Embry
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Nina S. Baggett
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - David B. Heisler
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Addison White
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Maarten F. de Jong
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Benjamin L. Kocsis
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Diana R. Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Neal M. Alto
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
| | - Don B. Gammon
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America
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10
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Sadeghi M, Divangahi M. Discovering adaptive features of innate immune memory. Immunol Rev 2024; 323:186-196. [PMID: 38563500 DOI: 10.1111/imr.13328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 03/11/2024] [Indexed: 04/04/2024]
Abstract
Conventionally, it was thought that innate immunity operated through a simple system of nonspecific responses to an insult. However, this perspective now seems overly simplistic. It has become evident that intricate cooperation and networking among various cells, receptors, signaling pathways, and protein complexes are essential for regulating and defining the overall activation status of the immune response, where the distinction between innate and adaptive immunity becomes ambiguous. Given the evolutionary timeline of vertebrates and the success of plants and invertebrates which depend solely on innate immunity, immune memory cannot be considered an innovation of only the lymphoid lineage. Indeed, the evolutionary innate immune memory program is a conserved mechanism whereby innate immune cells can induce a heightened response to a secondary stimulus due to metabolic and epigenetic reprogramming. Importantly, the longevity of this memory phenotype can be attributed to the reprogramming of self-renewing hematopoietic stem cells (HSCs) in the bone marrow, which is subsequently transmitted to lineage-committed innate immune cells. HSCs reside within a complex regulated network of immune and stromal cells that govern their two primary functions: self-renewal and differentiation. In this review, we delve into the emerging cellular and molecular mechanisms as well as metabolic pathways of innate memory in HSCs, which harbor substantial therapeutic promise.
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Affiliation(s)
- Mina Sadeghi
- Department of Medicine, McGill University Health Centre, McGill International TB Centre, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada
- Department of Microbiology & Immunology, McGill University Health Centre, McGill International TB Centre, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada
| | - Maziar Divangahi
- Department of Medicine, McGill University Health Centre, McGill International TB Centre, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada
- Department of Microbiology & Immunology, McGill University Health Centre, McGill International TB Centre, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada
- Department of Pathology, McGill University Health Centre, McGill International TB Centre, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada
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11
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Rechkoblit O, Sciaky D, Kreitler DF, Buku A, Kottur J, Aggarwal AK. Activation of CBASS Cap5 endonuclease immune effector by cyclic nucleotides. Nat Struct Mol Biol 2024; 31:767-776. [PMID: 38321146 DOI: 10.1038/s41594-024-01220-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 01/08/2024] [Indexed: 02/08/2024]
Abstract
The bacterial cyclic oligonucleotide-based antiphage signaling system (CBASS) is similar to the cGAS-STING system in humans, containing an enzyme that synthesizes a cyclic nucleotide on viral infection and an effector that senses the second messenger for the antiviral response. Cap5, containing a SAVED domain coupled to an HNH DNA endonuclease domain, is the most abundant CBASS effector, yet the mechanism by which it becomes activated for cell killing remains unknown. We present here high-resolution structures of full-length Cap5 from Pseudomonas syringae (Ps) with second messengers. The key to PsCap5 activation is a dimer-to-tetramer transition, whereby the binding of second messenger to dimer triggers an open-to-closed transformation of the SAVED domains, furnishing a surface for assembly of the tetramer. This movement propagates to the HNH domains, juxtaposing and converting two HNH domains into states for DNA destruction. These results show how Cap5 effects bacterial cell suicide and we provide proof-in-principle data that the CBASS can be extrinsically activated to limit bacterial infections.
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Affiliation(s)
- Olga Rechkoblit
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Daniela Sciaky
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dale F Kreitler
- Center for BioMolecular Structure NSLS‑II, Brookhaven National Laboratory, Upton, NY, USA
| | - Angeliki Buku
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jithesh Kottur
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Antiviral Research, Institute of Advanced Virology, Thiruvananthapuram, India
| | - Aneel K Aggarwal
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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12
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Prostova M, Kanevskaya A, Panteleev V, Lisitskaya L, Perfilova Tugaeva KV, Sluchanko NN, Esyunina D, Kulbachinskiy A. DNA-targeting short Argonautes complex with effector proteins for collateral nuclease activity and bacterial population immunity. Nat Microbiol 2024; 9:1368-1381. [PMID: 38622379 DOI: 10.1038/s41564-024-01654-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Accepted: 02/28/2024] [Indexed: 04/17/2024]
Abstract
Two prokaryotic defence systems, prokaryotic Argonautes (pAgos) and CRISPR-Cas, detect and cleave invader nucleic acids using complementary guides and the nuclease activities of pAgo or Cas proteins. However, not all pAgos are active nucleases. A large clade of short pAgos bind nucleic acid guides but lack nuclease activity, suggesting a different mechanism of action. Here we investigate short pAgos associated with a putative effector nuclease, NbaAgo from Novosphingopyxis baekryungensis and CmeAgo from Cupriavidus metallidurans. We show that these pAgos form a heterodimeric complex with co-encoded effector nucleases (short prokaryotic Argonaute, DNase and RNase associated (SPARDA)). RNA-guided target DNA recognition unleashes the nuclease activity of SPARDA leading to indiscriminate collateral cleavage of DNA and RNA. Activation of SPARDA by plasmids or phages results in degradation of cellular DNA and cell death or dormancy, conferring target-specific population protection and expanding the range of known prokaryotic immune systems.
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Affiliation(s)
- Maria Prostova
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
| | - Anna Kanevskaya
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
| | | | - Lidia Lisitskaya
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Kristina V Perfilova Tugaeva
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Nikolai N Sluchanko
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Daria Esyunina
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
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13
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Martínez M, Rizzuto I, Molina R. Knowing Our Enemy in the Antimicrobial Resistance Era: Dissecting the Molecular Basis of Bacterial Defense Systems. Int J Mol Sci 2024; 25:4929. [PMID: 38732145 PMCID: PMC11084316 DOI: 10.3390/ijms25094929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 05/13/2024] Open
Abstract
Bacteria and their phage adversaries are engaged in an ongoing arms race, resulting in the development of a broad antiphage arsenal and corresponding viral countermeasures. In recent years, the identification and utilization of CRISPR-Cas systems have driven a renewed interest in discovering and characterizing antiphage mechanisms, revealing a richer diversity than initially anticipated. Currently, these defense systems can be categorized based on the bacteria's strategy associated with the infection cycle stage. Thus, bacterial defense systems can degrade the invading genetic material, trigger an abortive infection, or inhibit genome replication. Understanding the molecular mechanisms of processes related to bacterial immunity has significant implications for phage-based therapies and the development of new biotechnological tools. This review aims to comprehensively cover these processes, with a focus on the most recent discoveries.
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Affiliation(s)
| | | | - Rafael Molina
- Department of Crystallography and Structural Biology, Instituto de Química-Física Blas Cabrera, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
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14
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Ganguly C, Rostami S, Long K, Aribam SD, Rajan R. Unity among the diverse RNA-guided CRISPR-Cas interference mechanisms. J Biol Chem 2024; 300:107295. [PMID: 38641067 PMCID: PMC11127173 DOI: 10.1016/j.jbc.2024.107295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/21/2024] Open
Abstract
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) systems are adaptive immune systems that protect bacteria and archaea from invading mobile genetic elements (MGEs). The Cas protein-CRISPR RNA (crRNA) complex uses complementarity of the crRNA "guide" region to specifically recognize the invader genome. CRISPR effectors that perform targeted destruction of the foreign genome have emerged independently as multi-subunit protein complexes (Class 1 systems) and as single multi-domain proteins (Class 2). These different CRISPR-Cas systems can cleave RNA, DNA, and protein in an RNA-guided manner to eliminate the invader, and in some cases, they initiate programmed cell death/dormancy. The versatile mechanisms of the different CRISPR-Cas systems to target and destroy nucleic acids have been adapted to develop various programmable-RNA-guided tools and have revolutionized the development of fast, accurate, and accessible genomic applications. In this review, we present the structure and interference mechanisms of different CRISPR-Cas systems and an analysis of their unified features. The three types of Class 1 systems (I, III, and IV) have a conserved right-handed helical filamentous structure that provides a backbone for sequence-specific targeting while using unique proteins with distinct mechanisms to destroy the invader. Similarly, all three Class 2 types (II, V, and VI) have a bilobed architecture that binds the RNA-DNA/RNA hybrid and uses different nuclease domains to cleave invading MGEs. Additionally, we highlight the mechanistic similarities of CRISPR-Cas enzymes with other RNA-cleaving enzymes and briefly present the evolutionary routes of the different CRISPR-Cas systems.
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Affiliation(s)
- Chhandosee Ganguly
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Saadi Rostami
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Kole Long
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Swarmistha Devi Aribam
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA.
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15
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Pradeu T, Thomma BPHJ, Girardin SE, Lemaitre B. The conceptual foundations of innate immunity: Taking stock 30 years later. Immunity 2024; 57:613-631. [PMID: 38599162 DOI: 10.1016/j.immuni.2024.03.007] [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: 01/14/2024] [Revised: 02/23/2024] [Accepted: 03/06/2024] [Indexed: 04/12/2024]
Abstract
While largely neglected over decades during which adaptive immunity captured most of the attention, innate immune mechanisms have now become central to our understanding of immunology. Innate immunity provides the first barrier to infection in vertebrates, and it is the sole mechanism of host defense in invertebrates and plants. Innate immunity also plays a critical role in maintaining homeostasis, shaping the microbiota, and in disease contexts such as cancer, neurodegeneration, metabolic syndromes, and aging. The emergence of the field of innate immunity has led to an expanded view of the immune system, which is no longer restricted to vertebrates and instead concerns all metazoans, plants, and even prokaryotes. The study of innate immunity has given rise to new concepts and language. Here, we review the history and definition of the core concepts of innate immunity, discussing their value and fruitfulness in the long run.
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Affiliation(s)
- Thomas Pradeu
- CNRS UMR 5164 ImmunoConcept, University of Bordeaux, Bordeaux, France; Department of Biological and Medical Sciences, University of Bordeaux, Bordeaux, France; Presidential Fellow, Chapman University, Orange, CA, USA.
| | - Bart P H J Thomma
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Stephen E Girardin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Bruno Lemaitre
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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16
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Cossart P, Hacker J, Holden DH, Normark S, Vogel J. Meeting report 'Microbiology 2023: from single cell to microbiome and host', an international interacademy conference in Würzburg. MICROLIFE 2024; 5:uqae008. [PMID: 38665235 PMCID: PMC11044969 DOI: 10.1093/femsml/uqae008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024]
Abstract
On September 20-22 September 2023, the international conference 'Microbiology 2023: from single cell to microbiome and host' convened microbiologists from across the globe for a very successful symposium, showcasing cutting-edge research in the field. Invited lecturers delivered exceptional presentations covering a wide range of topics, with a major emphasis on phages and microbiomes, on the relevant bacteria within these ecosystems, and their multifaceted roles in diverse environments. Discussions also spanned the intricate analysis of fundamental bacterial processes, such as cell division, stress resistance, and interactions with phages. Organized by four renowned Academies, the German Leopoldina, the French Académie des sciences, the Royal Society UK, and the Royal Swedish Academy of Sciences, the symposium provided a dynamic platform for experts to share insights and discoveries, leaving participants inspired and eager to integrate new knowledge into their respective projects. The success of Microbiology 2023 prompted the decision to host the next quadrennial academic meeting in Sweden. This choice underscores the commitment to fostering international collaboration and advancing the frontiers of microbiological knowledge. The transition to Sweden promises to be an exciting step in the ongoing global dialogue and specific collaborations on microbiology, a field where researchers will continue to push the boundaries of knowledge, understanding, and innovation not only in health and disease but also in ecology.
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Affiliation(s)
| | - Jörg Hacker
- German National Academy of Science Leopoldina, Jägerberg 1, D-06108 Halle, Germany
| | - David H Holden
- Department of Infectious Disease, Centre for Bacterial Resistance Biology, Flowers Building, South Kensington Campus, Exhibition Road, Imperial College London, London SW7 2AZ, United Kingdom
| | - Staffan Normark
- Karolinska Institute, Tumor-och-cellbiologi, C1 Microbial Pathogenesis, 17177 Stockholm, Sweden
| | - Jörg Vogel
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), University of Würzburg, D-97080 Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Josef-Schneider-Str2/Gebaude D15; É. D-97080 Würzburg, Germany
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17
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Mayo-Muñoz D, Pinilla-Redondo R, Camara-Wilpert S, Birkholz N, Fineran PC. Inhibitors of bacterial immune systems: discovery, mechanisms and applications. Nat Rev Genet 2024; 25:237-254. [PMID: 38291236 DOI: 10.1038/s41576-023-00676-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2023] [Indexed: 02/01/2024]
Abstract
To contend with the diversity and ubiquity of bacteriophages and other mobile genetic elements, bacteria have developed an arsenal of immune defence mechanisms. Bacterial defences include CRISPR-Cas, restriction-modification and a growing list of mechanistically diverse systems, which constitute the bacterial 'immune system'. As a response, bacteriophages and mobile genetic elements have evolved direct and indirect mechanisms to circumvent or block bacterial defence pathways and ensure successful infection. Recent advances in methodological and computational approaches, as well as the increasing availability of genome sequences, have boosted the discovery of direct inhibitors of bacterial defence systems. In this Review, we discuss methods for the discovery of direct inhibitors, their diverse mechanisms of action and perspectives on their emerging applications in biotechnology and beyond.
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Affiliation(s)
- David Mayo-Muñoz
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
| | - Rafael Pinilla-Redondo
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
- Section of Microbiology, University of Copenhagen, Copenhagen, Denmark.
| | | | - Nils Birkholz
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
- Genetics Otago, University of Otago, Dunedin, New Zealand.
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand.
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand.
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18
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Agapov A, Baker KS, Bedekar P, Bhatia RP, Blower TR, Brockhurst MA, Brown C, Chong CE, Fothergill JL, Graham S, Hall JP, Maestri A, McQuarrie S, Olina A, Pagliara S, Recker M, Richmond A, Shaw SJ, Szczelkun MD, Taylor TB, van Houte S, Went SC, Westra ER, White MF, Wright R. Multi-layered genome defences in bacteria. Curr Opin Microbiol 2024; 78:102436. [PMID: 38368839 DOI: 10.1016/j.mib.2024.102436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 02/20/2024]
Abstract
Bacteria have evolved a variety of defence mechanisms to protect against mobile genetic elements, including restriction-modification systems and CRISPR-Cas. In recent years, dozens of previously unknown defence systems (DSs) have been discovered. Notably, diverse DSs often coexist within the same genome, and some co-occur at frequencies significantly higher than would be expected by chance, implying potential synergistic interactions. Recent studies have provided evidence of defence mechanisms that enhance or complement one another. Here, we review the interactions between DSs at the mechanistic, regulatory, ecological and evolutionary levels.
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Affiliation(s)
- Aleksei Agapov
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | - Kate S Baker
- Department of Genetics, University of Cambridge, CB2 3EH, UK
| | - Paritosh Bedekar
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | - Rama P Bhatia
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | - Tim R Blower
- Department of Biosciences, Durham University, Stockton Road, Durham DH1 3LE, UK
| | - Michael A Brockhurst
- Division of Evolution, Infection and Genomics, School of Biological Sciences, University of Manchester, Dover Street, Manchester M13 9PT, UK
| | - Cooper Brown
- School of Biology, University of St Andrews, St Andrews KY16 9ST, UK
| | | | - Joanne L Fothergill
- Dept of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, UK
| | - Shirley Graham
- School of Biology, University of St Andrews, St Andrews KY16 9ST, UK
| | - James Pj Hall
- Dept of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, L69 7ZB, UK
| | - Alice Maestri
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | - Stuart McQuarrie
- School of Biology, University of St Andrews, St Andrews KY16 9ST, UK
| | - Anna Olina
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | | | - Mario Recker
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | - Anna Richmond
- ESI, Centre for Ecology and Conservation, University of Exeter, UK
| | - Steven J Shaw
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS6 7YB, UK
| | - Mark D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS6 7YB, UK
| | - Tiffany B Taylor
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | | | - Sam C Went
- Department of Biosciences, Durham University, Stockton Road, Durham DH1 3LE, UK
| | - Edze R Westra
- ESI, Centre for Ecology and Conservation, University of Exeter, UK.
| | - Malcolm F White
- School of Biology, University of St Andrews, St Andrews KY16 9ST, UK
| | - Rosanna Wright
- Division of Evolution, Infection and Genomics, School of Biological Sciences, University of Manchester, Dover Street, Manchester M13 9PT, UK
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19
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Billman ZP, Kovacs SB, Wei B, Kang K, Cissé OH, Miao EA. Caspase-1 activates gasdermin A in non-mammals. eLife 2024; 12:RP92362. [PMID: 38497531 PMCID: PMC10948149 DOI: 10.7554/elife.92362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024] Open
Abstract
Gasdermins oligomerize to form pores in the cell membrane, causing regulated lytic cell death called pyroptosis. Mammals encode five gasdermins that can trigger pyroptosis: GSDMA, B, C, D, and E. Caspase and granzyme proteases cleave the linker regions of and activate GSDMB, C, D, and E, but no endogenous activation pathways are yet known for GSDMA. Here, we perform a comprehensive evolutionary analysis of the gasdermin family. A gene duplication of GSDMA in the common ancestor of caecilian amphibians, reptiles, and birds gave rise to GSDMA-D in mammals. Uniquely in our tree, amphibian, reptile, and bird GSDMA group in a separate clade than mammal GSDMA. Remarkably, GSDMA in numerous bird species contain caspase-1 cleavage sites like YVAD or FASD in the linker. We show that GSDMA from birds, amphibians, and reptiles are all cleaved by caspase-1. Thus, GSDMA was originally cleaved by the host-encoded protease caspase-1. In mammals the caspase-1 cleavage site in GSDMA is disrupted; instead, a new protein, GSDMD, is the target of caspase-1. Mammal caspase-1 uses exosite interactions with the GSDMD C-terminal domain to confer the specificity of this interaction, whereas we show that bird caspase-1 uses a stereotypical tetrapeptide sequence to confer specificity for bird GSDMA. Our results reveal an evolutionarily stable association between caspase-1 and the gasdermin family, albeit a shifting one. Caspase-1 repeatedly changes its target gasdermin over evolutionary time at speciation junctures, initially cleaving GSDME in fish, then GSDMA in amphibians/reptiles/birds, and finally GSDMD in mammals.
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Affiliation(s)
- Zachary Paul Billman
- Department of Integrative Immunobiology; Molecular Genetics and Microbiology; Pathology; and Cell Biology, Duke University School of MedicineDurhamUnited States
- Department of Microbiology and Immunology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Stephen Bela Kovacs
- Department of Integrative Immunobiology; Molecular Genetics and Microbiology; Pathology; and Cell Biology, Duke University School of MedicineDurhamUnited States
- Department of Microbiology and Immunology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Bo Wei
- Department of Integrative Immunobiology; Molecular Genetics and Microbiology; Pathology; and Cell Biology, Duke University School of MedicineDurhamUnited States
| | - Kidong Kang
- Department of Integrative Immunobiology; Molecular Genetics and Microbiology; Pathology; and Cell Biology, Duke University School of MedicineDurhamUnited States
| | - Ousmane H Cissé
- Critical Care Medicine Department, National Institutes of Health Clinical CenterBethesdaUnited States
| | - Edward A Miao
- Department of Integrative Immunobiology; Molecular Genetics and Microbiology; Pathology; and Cell Biology, Duke University School of MedicineDurhamUnited States
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20
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Ledvina HE, Whiteley AT. Conservation and similarity of bacterial and eukaryotic innate immunity. Nat Rev Microbiol 2024:10.1038/s41579-024-01017-1. [PMID: 38418927 DOI: 10.1038/s41579-024-01017-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2024] [Indexed: 03/02/2024]
Abstract
Pathogens are ubiquitous and a constant threat to their hosts, which has led to the evolution of sophisticated immune systems in bacteria, archaea and eukaryotes. Bacterial immune systems encode an astoundingly large array of antiviral (antiphage) systems, and recent investigations have identified unexpected similarities between the immune systems of bacteria and animals. In this Review, we discuss advances in our understanding of the bacterial innate immune system and highlight the components, strategies and pathogen restriction mechanisms conserved between bacteria and eukaryotes. We summarize evidence for the hypothesis that components of the human immune system originated in bacteria, where they first evolved to defend against phages. Further, we discuss shared mechanisms that pathogens use to overcome host immune pathways and unexpected similarities between bacterial immune systems and interbacterial antagonism. Understanding the shared evolutionary path of immune components across domains of life and the successful strategies that organisms have arrived at to restrict their pathogens will enable future development of therapeutics that activate the human immune system for the precise treatment of disease.
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Affiliation(s)
- Hannah E Ledvina
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Aaron T Whiteley
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.
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21
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Ding W, Chen J, Zhao L, Wu S, Chen X, Chen H. Mitochondrial DNA leakage triggers inflammation in age-related cardiovascular diseases. Front Cell Dev Biol 2024; 12:1287447. [PMID: 38425502 PMCID: PMC10902119 DOI: 10.3389/fcell.2024.1287447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
Mitochondrial dysfunction is one of the hallmarks of cardiovascular aging. The leakage of mitochondrial DNA (mtDNA) is increased in senescent cells, which are resistant to programmed cell death such as apoptosis. Due to its similarity to prokaryotic DNA, mtDNA could be recognized by cellular DNA sensors and trigger innate immune responses, resulting in chronic inflammatory conditions during aging. The mechanisms include cGAS-STING signaling, TLR-9 and inflammasomes activation. Mitochondrial quality controls such as mitophagy could prevent mitochondria from triggering harmful inflammatory responses, but when this homeostasis is out of balance, mtDNA-induced inflammation could become pathogenic and contribute to age-related cardiovascular diseases. Here, we summarize recent studies on mechanisms by which mtDNA promotes inflammation and aging-related cardiovascular diseases, and discuss the potential value of mtDNA in early screening and as therapeutic targets.
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Affiliation(s)
- Wanyue Ding
- Heilongjiang Academy of Traditional Chinese Medicine, Harbin, China
| | - Jingyu Chen
- Department of Chinese Medicine Internal Medicine, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Lei Zhao
- Heilongjiang Academy of Traditional Chinese Medicine, Harbin, China
| | - Shuang Wu
- Southern Medical University Affiliated Qiqihar Hospital, The First Hospital of Qiqihar, Qiqihaer, Heilongjiang, China
| | - Xiaomei Chen
- Integrated Traditional Chinese and Western Medicine Syndrome Laboratory, School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong, China
| | - Hong Chen
- Heilongjiang Academy of Traditional Chinese Medicine, Harbin, China
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22
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Gallucci S. DNA at the center of mammalian innate immune recognition of bacterial biofilms. Trends Immunol 2024; 45:103-112. [PMID: 38281884 PMCID: PMC11032746 DOI: 10.1016/j.it.2023.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/20/2023] [Accepted: 12/20/2023] [Indexed: 01/30/2024]
Abstract
Historically, the study of innate immune detection of bacterial infections has focused on the recognition of pathogen-associated molecular patterns (PAMPs) from bacteria growing as single cells in planktonic phase. However, over the past two decades, studies have highlighted an adaptive advantage of bacteria: the formation of biofilms. These structures are complex fortresses that stand against a hostile environment, including antibiotics and immune responses. Extracellular DNA (eDNA) is a crucial component of the matrix of most known biofilms. In this opinion article, I propose that eDNA is a universal PAMP that the immune system uses to recognize biofilms. Outstanding questions concern the discrimination between biofilm-associated eDNA and DNA from planktonic bacteria, the innate receptors involved, and the immune response to biofilms.
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Affiliation(s)
- Stefania Gallucci
- Laboratory of Dendritic Cell Biology, Division of Innate Immunity, Department of Medicine, UMass Chan Medical School, Worcester, MA, USA.
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23
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Murphy MP, O'Neill LAJ. A break in mitochondrial endosymbiosis as a basis for inflammatory diseases. Nature 2024; 626:271-279. [PMID: 38326590 DOI: 10.1038/s41586-023-06866-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Accepted: 11/14/2023] [Indexed: 02/09/2024]
Abstract
Mitochondria retain bacterial traits due to their endosymbiotic origin, but host cells do not recognize them as foreign because the organelles are sequestered. However, the regulated release of mitochondrial factors into the cytosol can trigger cell death, innate immunity and inflammation. This selective breakdown in the 2-billion-year-old endosymbiotic relationship enables mitochondria to act as intracellular signalling hubs. Mitochondrial signals include proteins, nucleic acids, phospholipids, metabolites and reactive oxygen species, which have many modes of release from mitochondria, and of decoding in the cytosol and nucleus. Because these mitochondrial signals probably contribute to the homeostatic role of inflammation, dysregulation of these processes may lead to autoimmune and inflammatory diseases. A potential reason for the increased incidence of these diseases may be changes in mitochondrial function and signalling in response to such recent phenomena as obesity, dietary changes and other environmental factors. Focusing on the mixed heritage of mitochondria therefore leads to predictions for future insights, research paths and therapeutic opportunities. Thus, whereas mitochondria can be considered 'the enemy within' the cell, evolution has used this strained relationship in intriguing ways, with increasing evidence pointing to the recent failure of endosymbiosis being critical for the pathogenesis of inflammatory diseases.
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Affiliation(s)
- Michael P Murphy
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
- Department of Medicine, University of Cambridge, Cambridge, UK.
| | - Luke A J O'Neill
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland.
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24
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Huang Y, Pang Y, Xu Y, Liu L, Zhou H. The identification of regulatory ceRNA network involved in Drosophila Toll immune responses. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 151:105105. [PMID: 38013113 DOI: 10.1016/j.dci.2023.105105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 11/29/2023]
Abstract
Non-coding RNAs play important roles in the innate immunity of Drosophila, with various lncRNAs and miRNAs identified to maintain Drosophila innate immune homeostasis by regulating protein functions. However, it remains unclear whether interactions between lncRNAs and miRNAs give rise to a ceRNA network. In our previous study, we observed the highest differential expression levels of lncRNA-CR11538, lncRNA-CR33942, and lncRNA-CR46018 in wild-type flies after Gram-positive bacterial infection, prompting us to investigate their role in the regulation of Drosophila Toll immune response through RNA-seq analysis. Herein, our comprehensive bioinformatics analysis revealed that lncRNA-CR11538, lncRNA-CR33942, and lncRNA-CR46018 are involved in defense mechanisms and stimulus response. Moreover, lncRNA-CR11538 and lncRNA-CR46018 can also participate in the metabolic recovery processes following Gram-positive bacterial infection. Subsequently, we employed GSEA screening and RT-qPCR to identify seven miRNAs (miR-957, miR-1015, miR-982, miR-993, miR-1007, miR-193, and miR-978) that may be regulated by these three lncRNAs. Furthermore, we predicted the potential target genes in the Toll signaling pathway for these miRNAs and their interaction with the three lncRNAs using TargetScan and miRanda software and preliminary verification. As a result, we established a potential ceRNA regulatory network for Toll immune responses in Drosophila, comprising three lncRNAs and seven miRNAs. This study provides evidence of a ceRNA regulatory network in Drosophila Toll immune responses and offers novel insights into understanding the regulatory networks involved in the innate immunity of other animals.
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Affiliation(s)
- Yu Huang
- Laboratory for Comparative Genomics and Bioinformatics & Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, 210046, China
| | - Yujia Pang
- Laboratory for Comparative Genomics and Bioinformatics & Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, 210046, China; Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Yina Xu
- Laboratory for Comparative Genomics and Bioinformatics & Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, 210046, China
| | - Li Liu
- Laboratory for Comparative Genomics and Bioinformatics & Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, 210046, China
| | - Hongjian Zhou
- Laboratory for Comparative Genomics and Bioinformatics & Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, 210046, China; Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
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25
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Jenson JM, Chen ZJ. cGAS goes viral: A conserved immune defense system from bacteria to humans. Mol Cell 2024; 84:120-130. [PMID: 38181755 PMCID: PMC11168419 DOI: 10.1016/j.molcel.2023.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 01/07/2024]
Abstract
To survive, all organisms need the ability to accurately recognize and neutralize pathogens. As a result, many of the fundamental strategies that our innate immune system uses to fight infection have deep evolutionary roots. The innate immune sensor cyclic-GMP-AMP synthase (cGAS), an enzyme that plays a critical role in our bodies by sensing and signaling in response to microbial infection, is broadly conserved and has functional homologs in many vertebrates, invertebrates, and even bacteria. In this review, we will provide an overview of cGAS and cGAS-like signaling in eukaryotes before discussing cGAS-like homologs in bacteria.
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Affiliation(s)
- Justin M Jenson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA; Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
| | - Zhijian J Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA; Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
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26
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Billman ZP, Kovacs SB, Wei B, Kang K, Cissé OH, Miao EA. Caspase-1 activates gasdermin A in non-mammals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.28.559989. [PMID: 37987010 PMCID: PMC10659411 DOI: 10.1101/2023.09.28.559989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Gasdermins oligomerize to form pores in the cell membrane, causing regulated lytic cell death called pyroptosis. Mammals encode five gasdermins that can trigger pyroptosis: GSDMA, B, C, D, and E. Caspase and granzyme proteases cleave the linker regions of and activate GSDMB, C, D, and E, but no endogenous activation pathways are yet known for GSDMA. Here, we perform a comprehensive evolutionary analysis of the gasdermin family. A gene duplication of GSDMA in the common ancestor of caecilian amphibians, reptiles and birds gave rise to GSDMA-D in mammals. Uniquely in our tree, amphibian, reptile and bird GSDMA group in a separate clade than mammal GSDMA. Remarkably, GSDMA in numerous bird species contain caspase-1 cleavage sites like YVAD or FASD in the linker. We show that GSDMA from birds, amphibians, and reptiles are all cleaved by caspase-1. Thus, GSDMA was originally cleaved by the host-encoded protease caspase-1. In mammals the caspase-1 cleavage site in GSDMA is disrupted; instead, a new protein, GSDMD, is the target of caspase-1. Mammal caspase-1 uses exosite interactions with the GSDMD C-terminal domain to confer the specificity of this interaction, whereas we show that bird caspase-1 uses a stereotypical tetrapeptide sequence to confer specificity for bird GSDMA. Our results reveal an evolutionarily stable association between caspase-1 and the gasdermin family, albeit a shifting one. Caspase-1 repeatedly changes its target gasdermin over evolutionary time at speciation junctures, initially cleaving GSDME in fish, then GSDMA in amphibians/reptiles/birds, and finally GSDMD in mammals.
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Affiliation(s)
- Zachary P Billman
- Duke University School of Medicine
- National Institutes of Health University of North Carolina at Chapel Hill
- Departments of: Integrative Immunobiology; Molecular Genetics and Microbiology; Cell Biology; Pathology; Durham, NC, USA
- Department of Microbiology and Immunology; Chapel Hill, NC, USA
| | - Stephen B Kovacs
- Duke University School of Medicine
- National Institutes of Health University of North Carolina at Chapel Hill
- Departments of: Integrative Immunobiology; Molecular Genetics and Microbiology; Cell Biology; Pathology; Durham, NC, USA
- Department of Microbiology and Immunology; Chapel Hill, NC, USA
| | - Bo Wei
- Duke University School of Medicine
- Departments of: Integrative Immunobiology; Molecular Genetics and Microbiology; Cell Biology; Pathology; Durham, NC, USA
| | - Kidong Kang
- Duke University School of Medicine
- Departments of: Integrative Immunobiology; Molecular Genetics and Microbiology; Cell Biology; Pathology; Durham, NC, USA
| | - Ousmane H Cissé
- National Institutes of Health
- Critical Care Medicine Department; Bethesda, MD, USA
| | - Edward A Miao
- Duke University School of Medicine
- National Institutes of Health University of North Carolina at Chapel Hill
- Departments of: Integrative Immunobiology; Molecular Genetics and Microbiology; Cell Biology; Pathology; Durham, NC, USA
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27
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Song Y, Zhang S, Zhao N, Nong C, He Y, Bao R. Pseudomonas aeruginosa two-component system CprRS regulates HigBA expression and bacterial cytotoxicity in response to LL-37 stress. PLoS Pathog 2024; 20:e1011946. [PMID: 38198506 PMCID: PMC10805311 DOI: 10.1371/journal.ppat.1011946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 01/23/2024] [Accepted: 01/04/2024] [Indexed: 01/12/2024] Open
Abstract
Pseudomonas aeruginosa is a highly pathogenic bacterium known for its ability to sense and coordinate the production of virulence factors in response to host immune responses. However, the regulatory mechanisms underlying this process have remained largely elusive. In this study, we investigate the two-component system CprRS in P. aeruginosa and unveil the crucial role of the sensor protein CprS in sensing the human host defense peptide LL-37, thereby modulating bacterial virulence. We demonstrate that CprS acts as a phosphatase in the presence of LL-37, leading to the phosphorylation and activation of the response regulator CprR. The results prove that CprR directly recognizes a specific sequence within the promoter region of the HigBA toxin-antitoxin system, resulting in enhanced expression of the toxin HigB. Importantly, LL-37-induced HigB expression promotes the production of type III secretion system effectors, leading to reduced expression of proinflammatory cytokines and increased cytotoxicity towards macrophages. Moreover, mutations in cprS or cprR significantly impair bacterial survival in both macrophage and insect infection models. This study uncovers the regulatory mechanism of the CprRS system, enabling P. aeruginosa to detect and respond to human innate immune responses while maintaining a balanced virulence gene expression profile. Additionally, this study provides new evidence and insights into the complex regulatory system of T3SS in P. aeruginosa within the host environment, contributing to a better understanding of host-microbe communication and the development of novel strategies to combat bacterial infections.
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Affiliation(s)
- Yingjie Song
- College of Life Science, Sichuan Normal University, Chengdu, China
| | - Siping Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Ninglin Zhao
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Cheng Nong
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Yongxing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Rui Bao
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
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28
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Cortazar-Chinarro M, Richter-Boix A, Rödin-Mörch P, Halvarsson P, Logue JB, Laurila A, Höglund J. Association between the skin microbiome and MHC class II diversity in an amphibian. Mol Ecol 2024; 33:e17198. [PMID: 37933583 DOI: 10.1111/mec.17198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/20/2023] [Accepted: 10/26/2023] [Indexed: 11/08/2023]
Abstract
Microbiomes play an important role in determining the ecology and behaviour of their hosts. However, questions remain pertaining to how host genetics shape microbiomes, and how microbiome composition influences host fitness. We explored the effects of geography, evolutionary history and host genetics on the skin microbiome diversity and structure in a widespread amphibian. More specifically, we examined the association between bacterial diversity and composition and the major histocompatibility complex class II exon 2 diversity in 12 moor frog (Rana arvalis) populations belonging to two geographical clusters that show signatures of past and ongoing differential selection. We found that while bacterial alpha diversity did not differ between the two clusters, MHC alleles/supertypes and genetic diversity varied considerably depending on geography and evolutionary history. Bacterial alpha diversity was positively correlated with expected MHC heterozygosity and negatively with MHC nucleotide diversity. Furthermore, bacterial community composition showed significant variation between the two geographical clusters and between specific MHC alleles/supertypes. Our findings emphasize the importance of historical demographic events on hologenomic variation and provide new insights into how immunogenetic host variability and microbial diversity may jointly influence host fitness with consequences for disease susceptibility and population persistence.
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Affiliation(s)
- M Cortazar-Chinarro
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- MEMEG/Department of Biology, Lund University, Lund, Sweden
- Department of Earth Ocean and Atmospheric Sciences, Faculty of Science 2020-2207, University of British Columbia, Vancouver, British Columbia, Canada
| | - A Richter-Boix
- Department of Political and Social Science, Pompeu Fabra University, Barcelona, Spain
| | - P Rödin-Mörch
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - P Halvarsson
- Parasitology/Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - J B Logue
- Aquatic Ecology/Department of Biology, Lund University, Lund, Sweden
- SLU University Library, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - A Laurila
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - J Höglund
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
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29
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Shen Z, Lin Q, Yang XY, Fosuah E, Fu TM. Assembly-mediated activation of the SIR2-HerA supramolecular complex for anti-phage defense. Mol Cell 2023; 83:4586-4599.e5. [PMID: 38096827 DOI: 10.1016/j.molcel.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 09/25/2023] [Accepted: 11/09/2023] [Indexed: 12/24/2023]
Abstract
SIR2-HerA, a bacterial two-protein anti-phage defense system, induces bacterial death by depleting NAD+ upon phage infection. Biochemical reconstitution of SIR2, HerA, and the SIR2-HerA complex reveals a dynamic assembly process. Unlike other ATPases, HerA can form various oligomers, ranging from dimers to nonamers. When assembled with SIR2, HerA forms a hexamer and converts SIR2 from a nuclease to an NAD+ hydrolase, representing an unexpected regulatory mechanism mediated by protein assembly. Furthermore, high concentrations of ATP can inhibit NAD+ hydrolysis by the SIR2-HerA complex. Cryo-EM structures of the SIR2-HerA complex reveal a giant supramolecular assembly up to 1 MDa, with SIR2 as a dodecamer and HerA as a hexamer, crucial for anti-phage defense. Unexpectedly, the HerA hexamer resembles a spiral staircase and exhibits helicase activities toward dual-forked DNA. Together, we reveal the supramolecular assembly of SIR2-HerA as a unique mechanism for switching enzymatic activities and bolstering anti-phage defense strategies.
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Affiliation(s)
- Zhangfei Shen
- Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Qingpeng Lin
- Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Xiao-Yuan Yang
- Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA; Program of OSBP, The Ohio State University, Columbus, OH 43210, USA
| | - Elizabeth Fosuah
- Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA; Program of OSBP, The Ohio State University, Columbus, OH 43210, USA
| | - Tian-Min Fu
- Department of Biological Chemistry and Pharmacology, The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA; Program of OSBP, The Ohio State University, Columbus, OH 43210, USA.
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30
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Li Q, Wang S, Guo P, Feng Y, Yu W, Zhang H, Guo J, Li Y, Hu L, Pan J, Liao J, Tang Z. Mitochondrial DNA release mediated by TFAM deficiency promotes copper-induced mitochondrial innate immune response via cGAS-STING signalling in chicken hepatocytes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167315. [PMID: 37742962 DOI: 10.1016/j.scitotenv.2023.167315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/21/2023] [Accepted: 09/21/2023] [Indexed: 09/26/2023]
Abstract
Copper (Cu) is pollution metal that is a global concern due to its toxic effects. A recent study found that the release of mitochondrial DNA (mtDNA) into the cytoplasm can activate the innate immune response, but the exact mechanisms underlying the effect of Cu exposure remains unknown. In this study, we identified that the reduction in transcription Factor A (TFAM) led to mtDNA leakage into the cytoplasm under Cu exposure in hepatocytes, accompanied by the activation of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway-mediated innate immunity (increased expression of cGAS, STING, TANK-binding kinase-1 (TBK1), and interferon regulatory factor-3 (IRF3)) genes and proteins, and enhanced phosphorylation levels of TBK1 and IRF3). Subsequently, silencing TFAM (siTFAM) significantly aggravated mtDNA release and the innate immune response under Cu treatment. Mitochondrial DNA depletion alleviated Cu-induced innate immunity in hepatocytes, while mtDNA transfection further enhanced the innate immune response. Notably, the inhibition of STING effectively alleviated the phosphorylation levels of the TBK1 and IRF3 proteins induced by Cu, while the upregulation of STING aggravated the Cu-induced innate immunity. Furthermore, EtBr and H-151(a STING inhibitor) treatment dramatically reversed the effect of TFAM depletion on the sharpened innate immune response induced by Cu via the cGAS-STING pathway. In general, these findings demonstrated the TFAM deficiency promotes innate immunity by activating the mtDNA-cGAS-STING signalling pathway under Cu exposure in hepatocytes, providing new insight into Cu toxicology.
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Affiliation(s)
- Quanwei Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Shaofeng Wang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Pan Guo
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Yuanhong Feng
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Wenlan Yu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Hui Zhang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Jianying Guo
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Ying Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Lianmei Hu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Jiaqiang Pan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Jianzhao Liao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China
| | - Zhaoxin Tang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, Guangdong, PR China.
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31
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Rousset F. Innate immunity: the bacterial connection. Trends Immunol 2023; 44:945-953. [PMID: 37919213 DOI: 10.1016/j.it.2023.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/07/2023] [Accepted: 10/07/2023] [Indexed: 11/04/2023]
Abstract
Pathogens have fueled the diversification of intracellular defense strategies that collectively define cell-autonomous innate immunity. In bacteria, innate immunity is manifested by a broad arsenal of defense systems that provide protection against bacterial viruses, called phages. The complexity of the bacterial immune repertoire has only been realized recently and is now suggesting that innate immunity has commonalities across the tree of life: many components of eukaryotic innate immunity are found in bacteria where they protect against phages, including the cGAS-STING pathway, gasdermins, and viperins. Here, I summarize recent findings on the conservation of innate immune pathways between prokaryotes and eukaryotes and hypothesize that bacterial defense mechanisms can catalyze the discovery of novel molecular players of eukaryotic innate immunity.
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Affiliation(s)
- François Rousset
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
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32
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Korneenko TV, Pestov NB, Nevzorov IA, Daks AA, Trachuk KN, Solopova ON, Barlev NA. At the Crossroads of the cGAS-cGAMP-STING Pathway and the DNA Damage Response: Implications for Cancer Progression and Treatment. Pharmaceuticals (Basel) 2023; 16:1675. [PMID: 38139802 PMCID: PMC10747911 DOI: 10.3390/ph16121675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/21/2023] [Accepted: 11/21/2023] [Indexed: 12/24/2023] Open
Abstract
The evolutionary conserved DNA-sensing cGAS-STING innate immunity pathway represents one of the most important cytosolic DNA-sensing systems that is activated in response to viral invasion and/or damage to the integrity of the nuclear envelope. The key outcome of this pathway is the production of interferon, which subsequently stimulates the transcription of hundreds of genes. In oncology, the situation is complex because this pathway may serve either anti- or pro-oncogenic roles, depending on context. The prevailing understanding is that when the innate immune response is activated by sensing cytosolic DNA, such as DNA released from ruptured micronuclei, it results in the production of interferon, which attracts cytotoxic cells to destroy tumors. However, in tumor cells that have adjusted to significant chromosomal instability, particularly in relapsed, treatment-resistant cancers, the cGAS-STING pathway often supports cancer progression, fostering the epithelial-to-mesenchymal transition (EMT). Here, we review this intricate pathway in terms of its association with cancer progression, giving special attention to pancreatic ductal adenocarcinoma and gliomas. As the development of new cGAS-STING-modulating small molecules and immunotherapies such as oncolytic viruses involves serious challenges, we highlight several recent fundamental discoveries, such as the proton-channeling function of STING. These discoveries may serve as guiding lights for potential pharmacological advancements.
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Affiliation(s)
- Tatyana V. Korneenko
- Group of Cross-Linking Enzymes, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
| | - Nikolay B. Pestov
- Group of Cross-Linking Enzymes, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
- Institute of Biomedical Chemistry, Moscow 119121, Russia
- Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Moscow 108819, Russia
| | - Ivan A. Nevzorov
- Institute of Cytology, Tikhoretsky ave 4, St-Petersburg 194064, Russia
| | - Alexandra A. Daks
- Institute of Cytology, Tikhoretsky ave 4, St-Petersburg 194064, Russia
| | - Kirill N. Trachuk
- Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Moscow 108819, Russia
| | - Olga N. Solopova
- Research Institute of Experimental Diagnostics and Tumor Therapy, Blokhin National Medical Research Center of Oncology, Moscow 115478, Russia
| | - Nickolai A. Barlev
- Institute of Biomedical Chemistry, Moscow 119121, Russia
- Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Moscow 108819, Russia
- Institute of Cytology, Tikhoretsky ave 4, St-Petersburg 194064, Russia
- Institute of Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow 119991, Russia
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33
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Mogila I, Tamulaitiene G, Keda K, Timinskas A, Ruksenaite A, Sasnauskas G, Venclovas Č, Siksnys V, Tamulaitis G. Ribosomal stalk-captured CARF-RelE ribonuclease inhibits translation following CRISPR signaling. Science 2023; 382:1036-1041. [PMID: 38033086 DOI: 10.1126/science.adj2107] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/31/2023] [Indexed: 12/02/2023]
Abstract
Prokaryotic type III CRISPR-Cas antiviral systems employ cyclic oligoadenylate (cAn) signaling to activate a diverse range of auxiliary proteins that reinforce the CRISPR-Cas defense. Here we characterize a class of cAn-dependent effector proteins named CRISPR-Cas-associated messenger RNA (mRNA) interferase 1 (Cami1) consisting of a CRISPR-associated Rossmann fold sensor domain fused to winged helix-turn-helix and a RelE-family mRNA interferase domain. Upon activation by cyclic tetra-adenylate (cA4), Cami1 cleaves mRNA exposed at the ribosomal A-site thereby depleting mRNA and leading to cell growth arrest. The structures of apo-Cami1 and the ribosome-bound Cami1-cA4 complex delineate the conformational changes that lead to Cami1 activation and the mechanism of Cami1 binding to a bacterial ribosome, revealing unexpected parallels with eukaryotic ribosome-inactivating proteins.
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Affiliation(s)
- Irmantas Mogila
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Giedre Tamulaitiene
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Konstanty Keda
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Albertas Timinskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Audrone Ruksenaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Giedrius Sasnauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Česlovas Venclovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Virginijus Siksnys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Gintautas Tamulaitis
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
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34
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Fernandes AP, OhAinle M, Esteves PJ. Patterns of Evolution of TRIM Genes Highlight the Evolutionary Plasticity of Antiviral Effectors in Mammals. Genome Biol Evol 2023; 15:evad209. [PMID: 37988574 PMCID: PMC10709114 DOI: 10.1093/gbe/evad209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/03/2023] [Accepted: 11/07/2023] [Indexed: 11/23/2023] Open
Abstract
The innate immune system of mammals is formed by a complex web of interacting proteins, which together constitute the first barrier of entry for infectious pathogens. Genes from the E3-ubiquitin ligase tripartite motif (TRIM) family have been shown to play an important role in the innate immune system by restricting the activity of different retrovirus species. For example, TRIM5 and TRIM22 have both been associated with HIV restriction and are regarded as crucial parts of the antiretroviral machinery of mammals. Our analyses of positive selection corroborate the great significance of these genes for some groups of mammals. However, we also show that many species lack TRIM5 and TRIM22 altogether. By analyzing a large number of mammalian genomes, here we provide the first comprehensive view of the evolution of these genes in eutherians, showcasing that the pattern of accumulation of TRIM genes has been dissimilar across mammalian orders. Our data suggest that these differences are caused by the evolutionary plasticity of the immune system of eutherians, which have adapted to use different strategies to combat retrovirus infections. Altogether, our results provide insights into the dissimilar evolution of a representative family of restriction factors, highlighting an example of adaptive and idiosyncratic evolution in the innate immune system.
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Affiliation(s)
- Alexandre P Fernandes
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, Vairão, Portugal
| | - Molly OhAinle
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA
| | - Pedro J Esteves
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, Vairão, Portugal
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35
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Kulkarni M, Hardwick JM. Programmed Cell Death in Unicellular Versus Multicellular Organisms. Annu Rev Genet 2023; 57:435-459. [PMID: 37722687 DOI: 10.1146/annurev-genet-033123-095833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
Programmed cell death (self-induced) is intrinsic to all cellular life forms, including unicellular organisms. However, cell death research has focused on animal models to understand cancer, degenerative disorders, and developmental processes. Recently delineated suicidal death mechanisms in bacteria and fungi have revealed ancient origins of animal cell death that are intertwined with immune mechanisms, allaying earlier doubts that self-inflicted cell death pathways exist in microorganisms. Approximately 20 mammalian death pathways have been partially characterized over the last 35 years. By contrast, more than 100 death mechanisms have been identified in bacteria and a few fungi in recent years. However, cell death is nearly unstudied in most human pathogenic microbes that cause major public health burdens. Here, we consider how the current understanding of programmed cell death arose through animal studies and how recently uncovered microbial cell death mechanisms in fungi and bacteria resemble and differ from mechanisms of mammalian cell death.
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Affiliation(s)
- Madhura Kulkarni
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA; ,
| | - J Marie Hardwick
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA; ,
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
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36
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Tozzi A, Mazzeo M. The First Nucleic Acid Strands May Have Grown on Peptides via Primeval Reverse Translation. Acta Biotheor 2023; 71:23. [PMID: 37947915 DOI: 10.1007/s10441-023-09474-6] [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: 04/05/2023] [Accepted: 10/25/2023] [Indexed: 11/12/2023]
Abstract
The central dogma of molecular biology dictates that, with only a few exceptions, information proceeds from DNA to protein through an RNA intermediate. Examining the enigmatic steps from prebiotic to biological chemistry, we take another road suggesting that primordial peptides acted as template for the self-assembly of the first nucleic acids polymers. Arguing in favour of a sort of archaic "reverse translation" from proteins to RNA, our basic premise is a Hadean Earth where key biomolecules such as amino acids, polypeptides, purines, pyrimidines, nucleosides and nucleotides were available under different prebiotically plausible conditions, including meteorites delivery, shallow ponds and hydrothermal vents scenarios. Supporting a protein-first scenario alternative to the RNA world hypothesis, we propose the primeval occurrence of short two-dimensional peptides termed "selective amino acid- and nucleotide-matching oligopeptides" (henceforward SANMAOs) that noncovalently bind at the same time the polymerized amino acids and the single nucleotides dispersed in the prebiotic milieu. In this theoretical paper, we describe the chemical features of this hypothetical oligopeptide, its biological plausibility and its virtues from an evolutionary perspective. We provide a theoretical example of SANMAO's selective pairing between amino acids and nucleosides, simulating a poly-Glycine peptide that acts as a template to build a purinic chain corresponding to the glycine's extant triplet codon GGG. Further, we discuss how SANMAO might have endorsed the formation of low-fidelity RNA's polymerized strains, well before the appearance of the accurate genetic material's transmission ensured by the current translation apparatus.
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Affiliation(s)
- Arturo Tozzi
- Center for Nonlinear Science, Department of Physics, University of North Texas, 1155 Union Circle, #311427, Denton, TX, 76203-5017, USA.
| | - Marco Mazzeo
- Erredibi Srl, Via Pazzigno 117, 80146, Naples, Italy
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37
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Banh DV, Roberts CG, Morales-Amador A, Berryhill BA, Chaudhry W, Levin BR, Brady SF, Marraffini LA. Bacterial cGAS senses a viral RNA to initiate immunity. Nature 2023; 623:1001-1008. [PMID: 37968393 PMCID: PMC10686824 DOI: 10.1038/s41586-023-06743-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 10/12/2023] [Indexed: 11/17/2023]
Abstract
Cyclic oligonucleotide-based antiphage signalling systems (CBASS) protect prokaryotes from viral (phage) attack through the production of cyclic oligonucleotides, which activate effector proteins that trigger the death of the infected host1,2. How bacterial cyclases recognize phage infection is not known. Here we show that staphylococcal phages produce a structured RNA transcribed from the terminase subunit genes, termed CBASS-activating bacteriophage RNA (cabRNA), which binds to a positively charged surface of the CdnE03 cyclase and promotes the synthesis of the cyclic dinucleotide cGAMP to activate the CBASS immune response. Phages that escape the CBASS defence harbour mutations that lead to the generation of a longer form of the cabRNA that cannot activate CdnE03. As the mammalian cyclase OAS1 also binds viral double-stranded RNA during the interferon response, our results reveal a conserved mechanism for the activation of innate antiviral defence pathways.
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Affiliation(s)
- Dalton V Banh
- Laboratory of Bacteriology, The Rockefeller University, New York, NY, USA
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Cameron G Roberts
- Laboratory of Bacteriology, The Rockefeller University, New York, NY, USA
| | - Adrian Morales-Amador
- Laboratory of Genetically Encoded Small Molecules, The Rockefeller University, New York, NY, USA
| | | | - Waqas Chaudhry
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Bruce R Levin
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Sean F Brady
- Laboratory of Genetically Encoded Small Molecules, The Rockefeller University, New York, NY, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, New York, NY, USA.
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
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38
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Hardy A, Shomar H, Bernheim A. [Bacterial immunity: Uncovering a new world]. Med Sci (Paris) 2023; 39:862-868. [PMID: 38018930 DOI: 10.1051/medsci/2023163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023] Open
Abstract
Viruses are parasites that infect all living organisms, and bacteria are no exception. To defend themselves against their viruses (phages), bacteria have developed numerous and sophisticated defense mechanisms, our understanding of which is rapidly growing. In the 2000s, only a handful of mechanisms were known and only two of them seemed to be found in most bacteria. In 2018, a new key method based on genome analysis revealed that there were likely many others. Indeed, over the past five years, more than 150 new mechanisms have been discovered. It is now estimated that there are probably thousands. This remarkable diversity, paralleled with the tremendous viral diversity, is evident both in terms of possible combinations of systems in bacterial genomes and in molecular mechanisms. One of the most surprising observations emerging from the exploration of this diversity is the discovery of striking similarities between certain bacterial defense systems and antiviral systems in humans, as well as plant (and eukaryotes in general) immune systems. Contrary to the previously accepted paradigm, organisms as diverse as fungi, plants, bacteria and humans share certain molecular strategies to fight viral infections, suggesting that an underestimated part of eukaryotic antiviral immunity could have evolved from bacterial antiviral defense systems.
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Affiliation(s)
- Aël Hardy
- Institut Pasteur, université Paris Cité, Inserm U1284, Diversité moléculaire des microbes (Molecular Diversity of Microbes lab), 75015 Paris, France
| | - Helena Shomar
- Institut Pasteur, université Paris Cité, Inserm U1284, Diversité moléculaire des microbes (Molecular Diversity of Microbes lab), 75015 Paris, France
| | - Aude Bernheim
- Institut Pasteur, université Paris Cité, Inserm U1284, Diversité moléculaire des microbes (Molecular Diversity of Microbes lab), 75015 Paris, France
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39
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Song X, Lei S, Liu S, Liu Y, Fu P, Zeng Z, Yang K, Chen Y, Li M, She Q, Han W. Catalytically inactive long prokaryotic Argonaute systems employ distinct effectors to confer immunity via abortive infection. Nat Commun 2023; 14:6970. [PMID: 37914725 PMCID: PMC10620215 DOI: 10.1038/s41467-023-42793-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Argonaute proteins (Agos) bind short nucleic acids as guides and are directed by them to recognize target complementary nucleic acids. Diverse prokaryotic Agos (pAgos) play potential functions in microbial defense. The functions and mechanisms of a group of full-length yet catalytically inactive pAgos, long-B pAgos, remain unclear. Here, we show that most long-B pAgos are functionally connected with distinct associated proteins, including nucleases, Sir2-domain-containing proteins and trans-membrane proteins, respectively. The long-B pAgo-nuclease system (BPAN) is activated by guide RNA-directed target DNA recognition and performs collateral DNA degradation in vitro. In vivo, the system mediates genomic DNA degradation after sensing invading plasmid, which kills the infected cells and results in the depletion of the invader from the cell population. Together, the BPAN system provides immunoprotection via abortive infection. Our data also suggest that the defense strategy is employed by other long-B pAgos equipped with distinct associated proteins.
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Affiliation(s)
- Xinmi Song
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Sheng Lei
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Shunhang Liu
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Yanqiu Liu
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Pan Fu
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Zhifeng Zeng
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Ke Yang
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Yu Chen
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China
| | - Ming Li
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Qunxin She
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Shandong University, Binhai Road 72, 266237, Jimo, Qingdao, China
| | - Wenyuan Han
- State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Hubei Hongshan Laboratory, Huazhong Agricultural University, 430070, Wuhan, China.
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40
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Wang J, Li G, Wu M. Dissolving self to protect community: cGAS ubiquitin-like mechanism for bacteria to fight against phages. Sci Bull (Beijing) 2023; 68:2132-2134. [PMID: 37633829 DOI: 10.1016/j.scib.2023.08.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2023]
Affiliation(s)
- Junyi Wang
- Laboratory of Allergy and Precision Medicine, Department of Pulmonary and Critical Care Medicine, Chengdu Institute of Respiratory Health, The Third People's Hospital of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu 610000, China; State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau SAR 999078, China.
| | - Guoping Li
- Laboratory of Allergy and Precision Medicine, Department of Pulmonary and Critical Care Medicine, Chengdu Institute of Respiratory Health, The Third People's Hospital of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu 610000, China.
| | - Min Wu
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China.
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41
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Forsdyke DR. Aggregation-prone peptides from within a non-self-protein homoaggregate are preferred for MHC association: Historical overview. Scand J Immunol 2023; 98:e13306. [PMID: 38441340 DOI: 10.1111/sji.13306] [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: 03/18/2023] [Revised: 06/02/2023] [Accepted: 06/12/2023] [Indexed: 03/07/2024]
Abstract
New technologies assist re-evaluation of hypotheses on generation of immune cell repertoires and distinctions of self from non-self. Findings include positive correlations between peptide propensities to aggregate and their binding to major histocompatibility complex (MHC) proteins. This recalls the hypothesis that foreign proteins may homoaggregate in host cytosols prior to releasing their peptides (p) to form pMHC complexes. Clues to this included aggregation-related phenomena associated with infections (rouleaux formation, pyrexia, certain brain diseases). By virtue of 'promiscuous' gene expression by thymic presenting cells - perhaps adapted from earlier evolving gonadal mechanisms - developing T cells monitor surface pMHC clusterings. This evaluates intracellular concentrations of the corresponding proteins, and hence, following Burnet's two signal principle, degrees of self-reactivity. After positive selection in the thymic cortex for reactivity with 'near-self', high-level pMHC clustering suffices in the medulla for negatively selection. Following Burnet's principle, in the periphery low-level clustering suffices for T cell stimulation and high-level clustering again provokes negative selection (immunological tolerance). For evolving intracellular pathogens, fine-tuned polymorphisms of their host species have limited to 'near-self' some mimicking adaptations. It is proposed that while entire pathogen proteins may have evolved to minimize their aggregability, the greater aggregability of their peptides remains partially hidden within. Two-step proofreading mechanisms in prospective hosts select proteins containing aggregable peptide for the generation of pMHC clusters at the surface of presenting cells. Through mutations, some proteins of pathogens and cancer cells tend to converge towards the host 'near-self' that its T cells have auditioned to address.
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Affiliation(s)
- Donald R Forsdyke
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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42
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Slavik KM, Kranzusch PJ. CBASS to cGAS-STING: The Origins and Mechanisms of Nucleotide Second Messenger Immune Signaling. Annu Rev Virol 2023; 10:423-453. [PMID: 37380187 DOI: 10.1146/annurev-virology-111821-115636] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Host defense against viral pathogens is an essential function for all living organisms. In cell-intrinsic innate immunity, dedicated sensor proteins recognize molecular signatures of infection and communicate to downstream adaptor or effector proteins to activate immune defense. Remarkably, recent evidence demonstrates that much of the core machinery of innate immunity is shared across eukaryotic and prokaryotic domains of life. Here, we review a pioneering example of evolutionary conservation in innate immunity: the animal cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) signaling pathway and its ancestor in bacteria, CBASS (cyclic nucleotide-based antiphage signaling system) antiphage defense. We discuss the unique mechanism by which animal cGLRs (cGAS-like receptors) and bacterial CD-NTases (cGAS/dinucleotide-cyclase in Vibrio (DncV)-like nucleotidyltransferases) in these pathways link pathogen detection with immune activation using nucleotide second messenger signals. Comparing the biochemical, structural, and mechanistic details of cGAS-STING, cGLR signaling, and CBASS, we highlight emerging questions in the field and examine evolutionary pressures that may have shaped the origins of nucleotide second messenger signaling in antiviral defense.
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Affiliation(s)
- Kailey M Slavik
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA;
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Philip J Kranzusch
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA;
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Parker Institute for Cancer Immunotherapy at Dana-Farber Cancer Institute, Boston, Massachusetts, USA
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43
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Kottur J, Malik R, Aggarwal AK. Nucleic Acid Mediated Activation of a Short Prokaryotic Argonaute Immune System. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.17.558117. [PMID: 37745538 PMCID: PMC10516056 DOI: 10.1101/2023.09.17.558117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The continual pressure of invading DNA has led bacteria to develop numerous immune systems, including a short prokaryotic Argonaute (pAgo) TIR-APAZ system (SPARTA) that is activated by invading DNA to unleash its TIR domain for NAD(P)+ hydrolysis. To gain a molecular understanding of this activation process, we resolved a crystal structure of SPARTA heterodimer in the absence of guide RNA/target ssDNA at 2.66Å resolution and a cryo-EM structure of the SPARTA oligomer (tetramer of heterodimers) bound to guide RNA/target ssDNA at nominal 3.15-3.35Å resolution. The crystal structure provides a high-resolution view of the TIR-APAZ protein and the MID-PIWI domains of short pAgo - wherein, the APAZ domain emerges as equivalent to the N, L1 and L2 regions of long pAgos and the MID domain has a unique insertion (insert57). A comparison to cryo-EM structure reveals regions of the PIWI (loop10-9) and APAZ (helix αN) domains that reconfigure to relieve auto-inhibition to permit nucleic acid binding and transition to an active oligomer. Oligomerization is accompanied by the nucleation of the TIR domains in a parallel-strands arrangement for catalysis. Together, the structures provide a visualization of SPARTA before and after RNA/ssDNA binding and reveal the basis of SPARTA's active assembly leading to NAD(P)+ degradation and abortive infection.
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Affiliation(s)
- Jithesh Kottur
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Radhika Malik
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Aneel K. Aggarwal
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
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44
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Culbertson EM, Levin TC. Eukaryotic antiviral immune proteins arose via convergence, horizontal transfer, and ancient inheritance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.27.546753. [PMID: 37425898 PMCID: PMC10327000 DOI: 10.1101/2023.06.27.546753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Animals use a variety of cell-autonomous innate immune proteins to detect viral infections and prevent replication. Recent studies have discovered that a subset of mammalian antiviral proteins have homology to anti-phage defense proteins in bacteria, implying that there are aspects of innate immunity that are shared across the Tree of Life. While the majority of these studies have focused on characterizing the diversity and biochemical functions of the bacterial proteins, the evolutionary relationships between animal and bacterial proteins are less clear. This ambiguity is partly due to the long evolutionary distances separating animal and bacterial proteins, which obscures their relationships. Here, we tackle this problem for three innate immune families (CD-NTases [including cGAS], STINGs, and Viperins) by deeply sampling protein diversity across eukaryotes. We find that Viperins and OAS family CD-NTases are truly ancient immune proteins, likely inherited since the last eukaryotic common ancestor and possibly longer. In contrast, we find other immune proteins that arose via at least four independent events of horizontal gene transfer (HGT) from bacteria. Two of these events allowed algae to acquire new bacterial viperins, while two more HGT events gave rise to distinct superfamilies of eukaryotic CD-NTases: the Mab21 superfamily (containing cGAS) which has diversified via a series of animal-specific duplications, and a previously undefined eSMODS superfamily, which more closely resembles bacterial CD-NTases. Finally, we found that cGAS and STING proteins have substantially different histories, with STINGs arising via convergent domain shuffling in bacteria and eukaryotes. Overall, our findings paint a picture of eukaryotic innate immunity as highly dynamic, where eukaryotes build upon their ancient antiviral repertoires through the reuse of protein domains and by repeatedly sampling a rich reservoir of bacterial anti-phage genes.
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Affiliation(s)
| | - Tera C. Levin
- University of Pittsburgh, Department of Biological Sciences
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45
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Marino ND, Brodsky IE. Immunology: NACHT domain proteins get a prokaryotic origin story. Curr Biol 2023; 33:R875-R878. [PMID: 37607487 DOI: 10.1016/j.cub.2023.06.084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The NACHT domain is found in eukaryotic pattern recognition receptors that promote anti-microbial defense, mediating their oligomerization into immune signaling complexes. Kibby et al. uncover a superfamily of prokaryotic NACHT-containing proteins and demonstrate that some members of this family mediate anti-phage defense.
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Affiliation(s)
- Nicole D Marino
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Igor E Brodsky
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA.
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46
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Rousset F, Yirmiya E, Nesher S, Brandis A, Mehlman T, Itkin M, Malitsky S, Millman A, Melamed S, Sorek R. A conserved family of immune effectors cleaves cellular ATP upon viral infection. Cell 2023; 186:3619-3631.e13. [PMID: 37595565 DOI: 10.1016/j.cell.2023.07.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/18/2023] [Accepted: 07/12/2023] [Indexed: 08/20/2023]
Abstract
During viral infection, cells can deploy immune strategies that deprive viruses of molecules essential for their replication. Here, we report a family of immune effectors in bacteria that, upon phage infection, degrade cellular adenosine triphosphate (ATP) and deoxyadenosine triphosphate (dATP) by cleaving the N-glycosidic bond between the adenine and sugar moieties. These ATP nucleosidase effectors are widely distributed within multiple bacterial defense systems, including cyclic oligonucleotide-based antiviral signaling systems (CBASS), prokaryotic argonautes, and nucleotide-binding leucine-rich repeat (NLR)-like proteins, and we show that ATP and dATP degradation during infection halts phage propagation. By analyzing homologs of the immune ATP nucleosidase domain, we discover and characterize Detocs, a family of bacterial defense systems with a two-component phosphotransfer-signaling architecture. The immune ATP nucleosidase domain is also encoded within diverse eukaryotic proteins with immune-like architectures, and we show biochemically that eukaryotic homologs preserve the ATP nucleosidase activity. Our findings suggest that ATP and dATP degradation is a cell-autonomous innate immune strategy conserved across the tree of life.
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Affiliation(s)
- Francois Rousset
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Erez Yirmiya
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shahar Nesher
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Alexander Brandis
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tevie Mehlman
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Maxim Itkin
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sergey Malitsky
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Adi Millman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sarah Melamed
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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47
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Gu Y, Li H, Deep A, Enustun E, Zhang D, Corbett KD. Bacterial Shedu immune nucleases share a common enzymatic core regulated by diverse sensor domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552793. [PMID: 37609250 PMCID: PMC10441436 DOI: 10.1101/2023.08.10.552793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Prokaryotes encode diverse anti-bacteriophage immune systems, including the single-protein Shedu nuclease. Here we reveal the structural basis for activation of Bacillus cereus Shedu. In the inactive homotetramer, a key catalytic residue in Shedu's nuclease domain is sequestered away from the catalytic site. Activation involves a conformational change that completes the active site and promotes assembly of a homo-octamer for coordinated double-strand DNA cleavage. Removal of Shedu's N-terminal domain ectopically activates the enzyme, suggesting that this domain allosterically inhibits Shedu in the absence of infection. Bioinformatic analysis of nearly 8,000 Shedu homologs reveals remarkable diversity in their N-terminal regulatory domains: we identify 79 domain families falling into eight functional classes, including diverse nucleic acid binding, enzymatic, and other domains. Together, these data reveal Shedu as a broad family of immune nucleases with a common nuclease core regulated by diverse N-terminal domains that likely respond to a range of infection-related signals.
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Affiliation(s)
- Yajie Gu
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla CA 92093
| | - Huan Li
- Department of Biology, Saint Louis University, Saint Louis, MO 63103
| | - Amar Deep
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla CA 92093
| | - Eray Enustun
- Department of Molecular Biology, University of California San Diego, La Jolla CA 92093
| | - Dapeng Zhang
- Department of Biology, Saint Louis University, Saint Louis, MO 63103
| | - Kevin D. Corbett
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla CA 92093
- Department of Molecular Biology, University of California San Diego, La Jolla CA 92093
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48
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Huiting E, Bondy-Denomy J. Defining the expanding mechanisms of phage-mediated activation of bacterial immunity. Curr Opin Microbiol 2023; 74:102325. [PMID: 37178480 PMCID: PMC11080646 DOI: 10.1016/j.mib.2023.102325] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 04/07/2023] [Accepted: 04/08/2023] [Indexed: 05/15/2023]
Abstract
Due to recent discovery efforts, over 100 immune systems encoded by bacteria that antagonize bacteriophage (phage) replication have been uncovered. These systems employ direct and indirect mechanisms to detect phage infection and activate bacterial immunity. The most well-studied mechanisms are direct detection and activation by phage-associated molecular patterns (PhAMPs), such as phage DNA and RNA sequences, and expressed phage proteins that directly activate abortive infection systems. Phage effectors may also inhibit host processes and, therefore, indirectly activate immunity. Here, we discuss our current understanding of these protein PhAMPs and effectors expressed during various stages of the phage life cycle that activate immunity. Immune activators are predominantly identified from genetic approaches that isolate phage mutants that escape a bacterial immune system, coupled with biochemical validation. Although the mechanism of phage-mediated activation remains uncertain for most systems, it has become clear that each stage of the phage life cycle has the potential to induce a bacterial immune response.
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Affiliation(s)
- Erin Huiting
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Joseph Bondy-Denomy
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94158, USA; Innovative Genomics Institute, Berkeley, CA, USA.
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49
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Luthe T, Kever L, Thormann K, Frunzke J. Bacterial multicellular behavior in antiviral defense. Curr Opin Microbiol 2023; 74:102314. [PMID: 37030144 DOI: 10.1016/j.mib.2023.102314] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/09/2023] [Accepted: 03/10/2023] [Indexed: 04/08/2023]
Abstract
Multicellular behavior benefits seemingly simple organisms such as bacteria, by improving nutrient uptake, resistance to stresses, or by providing advantages in predatory interactions. Several recent studies have shown that this also extends to the defense against bacteriophages, which are omnipresent in almost all habitats. In this review, we summarize strategies conferring protection against phage infection at the multicellular level, covering secretion of small antiphage molecules or membrane vesicles, the role of quorum sensing in phage defense, the development of transient phage resistance, and the impact of biofilm components and architecture. Recent studies focusing on these topics push the boundaries of our understanding of the bacterial immune system and set the ground for an appreciation of bacterial multicellular behavior in antiviral defense.
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Rousset F, Sorek R. The evolutionary success of regulated cell death in bacterial immunity. Curr Opin Microbiol 2023; 74:102312. [PMID: 37030143 DOI: 10.1016/j.mib.2023.102312] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 04/09/2023]
Abstract
Bacteria employ a complex arsenal of immune mechanisms to defend themselves against phages. Recent studies demonstrate that these immune mechanisms frequently involve regulated cell death in response to phage infection. By sacrificing infected cells, this strategy prevents the spread of phages within the surrounding population. In this review, we discuss the principles of regulated cell death in bacterial defense, and show that over 70% of sequenced prokaryotes employ this strategy as part of their defensive arsenals. We highlight the modularity of defense systems involving regulated cell death, explaining how shuffling between phage-sensing and cell-killing protein domains dominates their evolution. Some of these defense systems are the evolutionary ancestors of key components of eukaryotic immunity, highlighting their importance in shaping the evolutionary trajectory of immune systems across the tree of life.
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