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Pourliotopoulou E, Karampatakis T, Kachrimanidou M. Exploring the Toxin-Mediated Mechanisms in Clostridioides difficile Infection. Microorganisms 2024; 12:1004. [PMID: 38792835 PMCID: PMC11124097 DOI: 10.3390/microorganisms12051004] [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: 04/20/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024] Open
Abstract
Clostridioides difficile infection (CDI) is the leading cause of nosocomial antibiotic-associated diarrhea, and colitis, with increasing incidence and healthcare costs. Its pathogenesis is primarily driven by toxins produced by the bacterium C. difficile, Toxin A (TcdA) and Toxin B (TcdB). Certain strains produce an additional toxin, the C. difficile transferase (CDT), which further enhances the virulence and pathogenicity of C. difficile. These toxins disrupt colonic epithelial barrier integrity, and induce inflammation and cellular damage, leading to CDI symptoms. Significant progress has been made in the past decade in elucidating the molecular mechanisms of TcdA, TcdB, and CDT, which provide insights into the management of CDI and the future development of novel treatment strategies based on anti-toxin therapies. While antibiotics are common treatments, high recurrence rates necessitate alternative therapies. Bezlotoxumab, targeting TcdB, is the only available anti-toxin, yet limitations persist, prompting ongoing research. This review highlights the current knowledge of the structure and mechanism of action of C. difficile toxins and their role in disease. By comprehensively describing the toxin-mediated mechanisms, this review provides insights for the future development of novel treatment strategies and the management of CDI.
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Affiliation(s)
- Evdokia Pourliotopoulou
- Department of Microbiology, Medical School, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece;
| | | | - Melania Kachrimanidou
- Department of Microbiology, Medical School, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece;
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2
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Jia J, Zoeschg M, Barth H, Pulliainen AT, Ernst K. The Chaperonin TRiC/CCT Inhibitor HSF1A Protects Cells from Intoxication with Pertussis Toxin. Toxins (Basel) 2024; 16:36. [PMID: 38251252 PMCID: PMC10819386 DOI: 10.3390/toxins16010036] [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: 11/02/2023] [Revised: 01/03/2024] [Accepted: 01/07/2024] [Indexed: 01/23/2024] Open
Abstract
Pertussis toxin (PT) is a bacterial AB5-toxin produced by Bordetella pertussis and a major molecular determinant of pertussis, also known as whooping cough, a highly contagious respiratory disease. In this study, we investigate the protective effects of the chaperonin TRiC/CCT inhibitor, HSF1A, against PT-induced cell intoxication. TRiC/CCT is a chaperonin complex that facilitates the correct folding of proteins, preventing misfolding and aggregation, and maintaining cellular protein homeostasis. Previous research has demonstrated the significance of TRiC/CCT in the functionality of the Clostridioides difficile TcdB AB-toxin. Our findings reveal that HSF1A effectively reduces the levels of ADP-ribosylated Gαi, the specific substrate of PT, in PT-treated cells, without interfering with enzyme activity in vitro or the cellular binding of PT. Additionally, our study uncovers a novel interaction between PTS1 and the chaperonin complex subunit CCT5, which correlates with reduced PTS1 signaling in cells upon HSF1A treatment. Importantly, HSF1A mitigates the adverse effects of PT on cAMP signaling in cellular systems. These results provide valuable insights into the mechanisms of PT uptake and suggest a promising starting point for the development of innovative therapeutic strategies to counteract pertussis toxin-mediated pathogenicity.
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Affiliation(s)
- Jinfang Jia
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Manuel Zoeschg
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | | | - Katharina Ernst
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
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3
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Papatheodorou P, Minton NP, Aktories K, Barth H. An Updated View on the Cellular Uptake and Mode-of-Action of Clostridioides difficile Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:219-247. [PMID: 38175478 DOI: 10.1007/978-3-031-42108-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Research on the human gut pathogen Clostridioides (C.) difficile and its toxins continues to attract much attention as a consequence of the threat to human health posed by hypervirulent strains. Toxin A (TcdA) and Toxin B (TcdB) are the two major virulence determinants of C. difficile. Both are single-chain proteins with a similar multidomain architecture. Certain hypervirulent C. difficile strains also produce a third toxin, namely binary toxin CDT (C. difficile transferase). C. difficile toxins are the causative agents of C. difficile-associated diseases (CDADs), such as antibiotics-associated diarrhea and pseudomembranous colitis. For that reason, considerable efforts have been expended to unravel their molecular mode-of-action and the cellular mechanisms responsible for their uptake. Many of these studies have been conducted in European laboratories. Here, we provide an update on our previous review (Papatheodorou et al. Adv Exp Med Biol, 2018) on important advances in C. difficile toxins research.
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Affiliation(s)
- Panagiotis Papatheodorou
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany.
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre, University of Nottingham, Nottingham, UK
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany
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4
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Nagahama M, Takehara M, Seike S, Sakaguchi Y. Cellular Uptake and Cytotoxicity of Clostridium perfringens Iota-Toxin. Toxins (Basel) 2023; 15:695. [PMID: 38133199 PMCID: PMC10747272 DOI: 10.3390/toxins15120695] [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: 11/22/2023] [Revised: 12/08/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023] Open
Abstract
Clostridium perfringens iota-toxin is composed of two separate proteins: a binding protein (Ib) that recognizes a host cell receptor and promotes the cellular uptake of a catalytic protein and (Ia) possessing ADP-ribosyltransferase activity that induces actin cytoskeleton disorganization. Ib exhibits the overall structure of bacterial pore-forming toxins (PFTs). Lipolysis-stimulated lipoprotein receptor (LSR) is defined as a host cell receptor for Ib. The binding of Ib to LSR causes an oligomer formation of Ib in lipid rafts of plasma membranes, mediating the entry of Ia into the cytoplasm. Ia induces actin cytoskeleton disruption via the ADP-ribosylation of G-actin and causes cell rounding and death. The binding protein alone disrupts the cell membrane and induces cytotoxicity in sensitive cells. Host cells permeabilized by the pore formation of Ib are repaired by a Ca2+-dependent plasma repair pathway. This review shows that the cellular uptake of iota-toxin utilizes a pathway of plasma membrane repair and that Ib alone induces cytotoxicity.
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Affiliation(s)
- Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan; (M.T.); (Y.S.)
| | - Masaya Takehara
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan; (M.T.); (Y.S.)
| | - Soshi Seike
- Laboratory of Molecular Microbiological Science, Faculty of Pharmaceutical Sciences, Hiroshima International University, Kure, Hiroshima 737-0112, Japan;
| | - Yoshihiko Sakaguchi
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan; (M.T.); (Y.S.)
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5
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Lisboa J, Pereira C, Pinto RD, Rodrigues IS, Pereira LMG, Pinheiro B, Oliveira P, Pereira PJB, Azevedo JE, Durand D, Benz R, do Vale A, Dos Santos NMS. Unconventional structure and mechanisms for membrane interaction and translocation of the NF-κB-targeting toxin AIP56. Nat Commun 2023; 14:7431. [PMID: 37973928 PMCID: PMC10654918 DOI: 10.1038/s41467-023-43054-z] [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: 05/15/2023] [Accepted: 10/30/2023] [Indexed: 11/19/2023] Open
Abstract
Bacterial AB toxins are secreted key virulence factors that are internalized by target cells through receptor-mediated endocytosis, translocating their enzymatic domain to the cytosol from endosomes (short-trip) or the endoplasmic reticulum (long-trip). To accomplish this, bacterial AB toxins evolved a multidomain structure organized into either a single polypeptide chain or non-covalently associated polypeptide chains. The prototypical short-trip single-chain toxin is characterized by a receptor-binding domain that confers cellular specificity and a translocation domain responsible for pore formation whereby the catalytic domain translocates to the cytosol in an endosomal acidification-dependent way. In this work, the determination of the three-dimensional structure of AIP56 shows that, instead of a two-domain organization suggested by previous studies, AIP56 has three-domains: a non-LEE encoded effector C (NleC)-like catalytic domain associated with a small middle domain that contains the linker-peptide, followed by the receptor-binding domain. In contrast to prototypical single-chain AB toxins, AIP56 does not comprise a typical structurally complex translocation domain; instead, the elements involved in translocation are scattered across its domains. Thus, the catalytic domain contains a helical hairpin that serves as a molecular switch for triggering the conformational changes necessary for membrane insertion only upon endosomal acidification, whereas the middle and receptor-binding domains are required for pore formation.
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Affiliation(s)
- Johnny Lisboa
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal.
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal.
| | - Cassilda Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Rute D Pinto
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
| | - Inês S Rodrigues
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Liliana M G Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
| | - Bruno Pinheiro
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
- Doctoral Program in Molecular and Cell Biology (MCbiology), Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto, Porto, Portugal
| | - Pedro Oliveira
- EPIUnit, ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Pedro José Barbosa Pereira
- Biomolecular Structure Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
- Macromolecular Structure Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Jorge E Azevedo
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
- Organelle Biogenesis and Function, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
- Organelle Biogenesis and Function, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Dominique Durand
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Roland Benz
- Science Faculty, Constructor University, Bremen, Germany
| | - Ana do Vale
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Nuno M S Dos Santos
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal.
- Fish Immunology and Vaccinology Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal.
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6
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Jia J, Braune-Yan M, Lietz S, Wahba M, Pulliainen AT, Barth H, Ernst K. Domperidone Inhibits Clostridium botulinum C2 Toxin and Bordetella pertussis Toxin. Toxins (Basel) 2023; 15:412. [PMID: 37505681 PMCID: PMC10467066 DOI: 10.3390/toxins15070412] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/13/2023] [Accepted: 06/20/2023] [Indexed: 07/29/2023] Open
Abstract
Bordetella pertussis toxin (PT) and Clostridium botulinum C2 toxin are ADP-ribosylating toxins causing severe diseases in humans and animals. They share a common translocation mechanism requiring the cellular chaperones Hsp90 and Hsp70, cyclophilins, and FK506-binding proteins to transport the toxins' enzyme subunits into the cytosol. Inhibitors of chaperone activities have been shown to reduce the amount of transported enzyme subunits into the cytosol of cells, thus protecting cells from intoxication by these toxins. Recently, domperidone, an approved dopamine receptor antagonist drug, was found to inhibit Hsp70 activity. Since Hsp70 is required for cellular toxin uptake, we hypothesized that domperidone also protects cells from intoxication with PT and C2. The inhibition of intoxication by domperidone was demonstrated by analyzing the ADP-ribosylation status of the toxins' specific substrates. Domperidone had no inhibitory effect on the receptor-binding or enzyme activity of the toxins, but it inhibited the pH-driven membrane translocation of the enzyme subunit of the C2 toxin and reduced the amount of PTS1 in cells. Taken together, our results indicate that domperidone is a potent inhibitor of PT and C2 toxins in cells and therefore might have therapeutic potential by repurposing domperidone to treat diseases caused by bacterial toxins that require Hsp70 for their cellular uptake.
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Affiliation(s)
- Jinfang Jia
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Maria Braune-Yan
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Stefanie Lietz
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Mary Wahba
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | | | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Katharina Ernst
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
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7
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Braune-Yan M, Jia J, Wahba M, Schmid J, Papatheodorou P, Barth H, Ernst K. Domperidone Protects Cells from Intoxication with Clostridioides difficile Toxins by Inhibiting Hsp70-Assisted Membrane Translocation. Toxins (Basel) 2023; 15:384. [PMID: 37368685 DOI: 10.3390/toxins15060384] [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: 05/18/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Clostridioides difficile infections cause severe symptoms ranging from diarrhea to pseudomembranous colitis due to the secretion of AB-toxins, TcdA and TcdB. Both toxins are taken up into cells through receptor-mediated endocytosis, autoproteolytic processing and translocation of their enzyme domains from acidified endosomes into the cytosol. The enzyme domains glucosylate small GTPases such as Rac1, thereby inhibiting processes such as actin cytoskeleton regulation. Here, we demonstrate that specific pharmacological inhibition of Hsp70 activity protected cells from TcdB intoxication. In particular, the established inhibitor VER-155008 and the antiemetic drug domperidone, which was found to be an Hsp70 inhibitor, reduced the number of cells with TcdB-induced intoxication morphology in HeLa, Vero and intestinal CaCo-2 cells. These drugs also decreased the intracellular glucosylation of Rac1 by TcdB. Domperidone did not inhibit TcdB binding to cells or enzymatic activity but did prevent membrane translocation of TcdB's glucosyltransferase domain into the cytosol. Domperidone also protected cells from intoxication with TcdA as well as CDT toxin produced by hypervirulent strains of Clostridioides difficile. Our results reveal Hsp70 requirement as a new aspect of the cellular uptake mechanism of TcdB and identified Hsp70 as a novel drug target for potential therapeutic strategies required to combat severe Clostridioides difficile infections.
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Affiliation(s)
- Maria Braune-Yan
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Jinfang Jia
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Mary Wahba
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Johannes Schmid
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Panagiotis Papatheodorou
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Katharina Ernst
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
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8
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Beitzinger C, Kronhardt A, Benz R. Chloroquine-analogues block anthrax protective antigen channels in steady-state and kinetic studies. Toxicology 2023; 492:153547. [PMID: 37201861 DOI: 10.1016/j.tox.2023.153547] [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: 03/30/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
The tripartite anthrax toxin from Bacillus anthracis represents the prototype of A-B type of toxins, where the effector A (an enzymatic subunit) is transported with the help of a binding component B into a target cell. Anthrax toxin consists of three different molecules, two effectors, lethal factor (LF) and edema factor (EF) and the binding component also known as protective antigen (PA). PA forms heptamers or octamers following binding to host cell's receptors and mediates the translocation of the effectors into the cytosol via the endosomal pathway. The cation-selective PA63-channel is able to reconstitute in lipid membranes and can be blocked by chloroquine and other heterocyclic compounds. This suggests that the PA63-channel contains a binding site for quinolines. In this study, we investigated the structure-function relationship of different quinolines for the block of the PA63-channel. The affinity of the different chloroquine analogues to the PA63-channel as provided by the equilibrium dissociation constant was measured using titrations. Some quinolines had a much higher affinity to the PA63-channel than chloroquine itself. We also performed ligand-induced current noise measurements using fast Fourier transformation to get insight in the kinetics of the binding of some quinolines to the PA63-channel. The on-rate constants of ligand binding were around 108M-1·s-1 at 150mM KCl and were only little dependent on the individual quinoline. The off-rates varied between 4s-1 and 160s-1 and depended much more on the structure of the molecules than the on-rate constants. The possible use of the 4-aminoquinolines as a therapy is discussed.
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Affiliation(s)
- Christoph Beitzinger
- Rudolf Virchow Center, Research Center for Experimental Biomedicine, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany
| | - Angelika Kronhardt
- Rudolf Virchow Center, Research Center for Experimental Biomedicine, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany
| | - Roland Benz
- Science Faculty, Constructor University Bremen, Campus-Ring 1, 28759 Bremen, Germany.
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Cheng JKJ, Unnikrishnan M. Clostridioides difficile infection: traversing host-pathogen interactions in the gut. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36848200 DOI: 10.1099/mic.0.001306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
C. difficile is the primary cause for nosocomial infective diarrhoea. For a successful infection, C. difficile must navigate between resident gut bacteria and the harsh host environment. The perturbation of the intestinal microbiota by broad-spectrum antibiotics alters the composition and the geography of the gut microbiota, deterring colonization resistance, and enabling C. difficile to colonize. This review will discuss how C. difficile interacts with and exploits the microbiota and the host epithelium to infect and persist. We provide an overview of C. difficile virulence factors and their interactions with the gut to aid adhesion, cause epithelial damage and mediate persistence. Finally, we document the host responses to C. difficile, describing the immune cells and host pathways that are associated and triggered during C. difficile infection.
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Affiliation(s)
- Jeffrey K J Cheng
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | - Meera Unnikrishnan
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
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10
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CRISPR screens in Drosophila cells identify Vsg as a Tc toxin receptor. Nature 2022; 610:349-355. [PMID: 36171290 PMCID: PMC9631961 DOI: 10.1038/s41586-022-05250-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 08/18/2022] [Indexed: 11/08/2022]
Abstract
Entomopathogenic nematodes are widely used as biopesticides1,2. Their insecticidal activity depends on symbiotic bacteria such as Photorhabdus luminescens, which produces toxin complex (Tc) toxins as major virulence factors3-6. No protein receptors are known for any Tc toxins, which limits our understanding of their specificity and pathogenesis. Here we use genome-wide CRISPR-Cas9-mediated knockout screening in Drosophila melanogaster S2R+ cells and identify Visgun (Vsg) as a receptor for an archetypal P. luminescens Tc toxin (pTc). The toxin recognizes the extracellular O-glycosylated mucin-like domain of Vsg that contains high-density repeats of proline, threonine and serine (HD-PTS). Vsg orthologues in mosquitoes and beetles contain HD-PTS and can function as pTc receptors, whereas orthologues without HD-PTS, such as moth and human versions, are not pTc receptors. Vsg is expressed in immune cells, including haemocytes and fat body cells. Haemocytes from Vsg knockout Drosophila are resistant to pTc and maintain phagocytosis in the presence of pTc, and their sensitivity to pTc is restored through the transgenic expression of mosquito Vsg. Last, Vsg knockout Drosophila show reduced bacterial loads and lethality from P. luminescens infection. Our findings identify a proteinaceous Tc toxin receptor, reveal how Tc toxins contribute to P. luminescens pathogenesis, and establish a genome-wide CRISPR screening approach for investigating insecticidal toxins and pathogens.
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11
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Ernst K. Requirement of Peptidyl-Prolyl Cis/Trans isomerases and chaperones for cellular uptake of bacterial AB-type toxins. Front Cell Infect Microbiol 2022; 12:938015. [PMID: 35992160 PMCID: PMC9387773 DOI: 10.3389/fcimb.2022.938015] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/15/2022] [Indexed: 11/30/2022] Open
Abstract
Bacterial AB-type toxins are proteins released by the producing bacteria and are the causative agents for several severe diseases including cholera, whooping cough, diphtheria or enteric diseases. Their unique AB-type structure enables their uptake into mammalian cells via sophisticated mechanisms exploiting cellular uptake and transport pathways. The binding/translocation B-subunit facilitates binding of the toxin to a specific receptor on the cell surface. This is followed by receptor-mediated endocytosis. Then the enzymatically active A-subunit either escapes from endosomes in a pH-dependent manner or the toxin is further transported through the Golgi to the endoplasmic reticulum from where the A-subunit translocates into the cytosol. In the cytosol, the A-subunits enzymatically modify a specific substrate which leads to cellular reactions resulting in clinical symptoms that can be life-threatening. Both intracellular uptake routes require the A-subunit to unfold to either fit through a pore formed by the B-subunit into the endosomal membrane or to be recognized by the ER-associated degradation pathway. This led to the hypothesis that folding helper enzymes such as chaperones and peptidyl-prolyl cis/trans isomerases are required to assist the translocation of the A-subunit into the cytosol and/or facilitate their refolding into an enzymatically active conformation. This review article gives an overview about the role of heat shock proteins Hsp90 and Hsp70 as well as of peptidyl-prolyl cis/trans isomerases of the cyclophilin and FK506 binding protein families during uptake of bacterial AB-type toxins with a focus on clostridial binary toxins Clostridium botulinum C2 toxin, Clostridium perfringens iota toxin, Clostridioides difficile CDT toxin, as well as diphtheria toxin, pertussis toxin and cholera toxin.
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12
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Kordus SL, Thomas AK, Lacy DB. Clostridioides difficile toxins: mechanisms of action and antitoxin therapeutics. Nat Rev Microbiol 2022; 20:285-298. [PMID: 34837014 PMCID: PMC9018519 DOI: 10.1038/s41579-021-00660-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 01/03/2023]
Abstract
Clostridioides difficile is a Gram-positive anaerobe that can cause a spectrum of disorders that range in severity from mild diarrhoea to fulminant colitis and/or death. The bacterium produces up to three toxins, which are considered the major virulence factors in C. difficile infection. These toxins promote inflammation, tissue damage and diarrhoea. In this Review, we highlight recent biochemical and structural advances in our understanding of the mechanisms that govern host-toxin interactions. Understanding how C. difficile toxins affect the host forms a foundation for developing novel strategies for treatment and prevention of C. difficile infection.
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Affiliation(s)
- Shannon L. Kordus
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - Audrey K. Thomas
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,The Veterans Affairs, Tennessee Valley Healthcare, System, Nashville, TN, USA,
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13
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Martínez-Meléndez A, Cruz-López F, Morfin-Otero R, Maldonado-Garza HJ, Garza-González E. An Update on Clostridioides difficile Binary Toxin. Toxins (Basel) 2022; 14:toxins14050305. [PMID: 35622552 PMCID: PMC9146464 DOI: 10.3390/toxins14050305] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 01/01/2023] Open
Abstract
Infection with Clostridioides difficile (CDI), a common healthcare-associated infection, includes symptoms ranging from mild diarrhea to severe cases of pseudomembranous colitis. Toxin A (TcdA) and toxin B (TcdB) cause cytotoxicity and cellular detachment from intestinal epithelium and are responsible for CDI symptomatology. Approximately 20% of C. difficile strains produce a binary toxin (CDT) encoded by the tcdA and tcdB genes, which is thought to enhance TcdA and TcdB toxicity; however, the role of CDT in CDI remains controversial. Here, we focused on describing the main features of CDT and its impact on the host, clinical relevance, epidemiology, and potential therapeutic approaches.
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Affiliation(s)
- Adrián Martínez-Meléndez
- Subdirección Académica de Químico Farmacéutico Biólogo, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Pedro de Alba S/N, Cd Universitaria, San Nicolás de los Garza 66450, Nuevo Leon, Mexico; (A.M.-M.); (F.C.-L.)
| | - Flora Cruz-López
- Subdirección Académica de Químico Farmacéutico Biólogo, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Pedro de Alba S/N, Cd Universitaria, San Nicolás de los Garza 66450, Nuevo Leon, Mexico; (A.M.-M.); (F.C.-L.)
| | - Rayo Morfin-Otero
- Instituto de Patología Infecciosa y Experimental “Dr. Francisco Ruiz Sánchez”, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Calle Hospital 308, Colonia el Retiro, Guadalajara 44280, Jalisco, Mexico;
| | - Héctor J. Maldonado-Garza
- Servicio de Gastroenterología, Facultad de Medicina/Hospital Universitario “Dr. José Eleuterio González”, Universidad Autónoma de Nuevo León, Av. Francisco I. Madero Pte. S/N y Av. José E. González, Col. Mitras Centro, Monterrey 64460, Nuevo Leon, Mexico;
| | - Elvira Garza-González
- Departamento de Bioquímica y Medicina Molecular, Facultad de Medicina y Hospital Universitario “Dr. José Eleuterio González”, Universidad Autónoma de Nuevo León, Av. Francisco I. Madero Pte. S/N y Av. José E. González, Col. Mitras Centro, Monterrey 64460, Nuevo Leon, Mexico
- Correspondence:
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14
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Ernst K. Novel Strategies to Inhibit Pertussis Toxin. Toxins (Basel) 2022; 14:187. [PMID: 35324684 PMCID: PMC8951090 DOI: 10.3390/toxins14030187] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 11/25/2022] Open
Abstract
Pertussis, also known as whooping cough, is a respiratory disease caused by infection with Bordetella pertussis, which releases several virulence factors, including the AB-type pertussis toxin (PT). The characteristic symptom is severe, long-lasting paroxysmal coughing. Especially in newborns and infants, pertussis symptoms, such as leukocytosis, can become life-threatening. Despite an available vaccination, increasing case numbers have been reported worldwide, including Western countries such as Germany and the USA. Antibiotic treatment is available and important to prevent further transmission. However, antibiotics only reduce symptoms if administered in early stages, which rarely occurs due to a late diagnosis. Thus, no causative treatments against symptoms of whooping cough are currently available. The AB-type protein toxin PT is a main virulence factor and consists of a binding subunit that facilitates transport of an enzyme subunit into the cytosol of target cells. There, the enzyme subunit ADP-ribosylates inhibitory α-subunits of G-protein coupled receptors resulting in disturbed cAMP signaling. As an important virulence factor associated with severe symptoms, such as leukocytosis, and poor outcomes, PT represents an attractive drug target to develop novel therapeutic strategies. In this review, chaperone inhibitors, human peptides, small molecule inhibitors, and humanized antibodies are discussed as novel strategies to inhibit PT.
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Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany
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15
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Kellner A, Cherubin P, Harper JK, Teter K. Proline Isomerization as a Key Determinant for Hsp90-Toxin Interactions. Front Cell Infect Microbiol 2021; 11:771653. [PMID: 34746036 PMCID: PMC8569296 DOI: 10.3389/fcimb.2021.771653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 10/05/2021] [Indexed: 11/30/2022] Open
Abstract
The A chains of ADP-ribosylating toxins exploit Hsp90 for translocation into the host cytosol. Here, we hypothesize that cis proline residues play a key role in toxin recognition by Hsp90. Our model is largely derived from studies on the unusual interplay between Hsp90 and the catalytic A1 subunit of cholera toxin (CTA1), including the recent identification of an RPPDEI-like binding motif for Hsp90 in CTA1 and several other bacterial toxins. Cis/trans proline isomerization is known to influence protein-protein interactions and protein structure/function, but it has not yet been proposed to affect Hsp90-toxin interactions. Our model thus provides a new framework to understand the molecular basis for Hsp90 chaperone function and Hsp90-driven toxin translocation.
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Affiliation(s)
- Alisha Kellner
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, United States
| | - Patrick Cherubin
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, United States
| | - James K Harper
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Ken Teter
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, United States
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16
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Hirschenberger M, Stadler N, Fellermann M, Sparrer KMJ, Kirchhoff F, Barth H, Papatheodorou P. CRISPA: A Non-viral, Transient Cas9 Delivery System Based on Reengineered Anthrax Toxin. Front Pharmacol 2021; 12:770283. [PMID: 34733166 PMCID: PMC8558532 DOI: 10.3389/fphar.2021.770283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/01/2021] [Indexed: 11/13/2022] Open
Abstract
Translating the CRISPR/Cas9 genome editing technology into clinics is still hampered by rather unspecific, unsafe and/or inconvenient approaches for the delivery of its main components - the Cas9 endonuclease and a guide RNA - into cells. Here, we describe the development of a novel transient and non-viral Cas9 delivery strategy based on the translocation machinery of the Bacillus anthracis anthrax toxin, PA (protective antigen). We show that Cas9 variants fused to the N-terminus of the lethal factor or to a hexahistidine tag are shuttled through channels formed by PA into the cytosol of human cells. As proof-of-principle, we applied our new approach, denoted as CRISPA, to knock out lipolysis-stimulated lipoprotein receptor (LSR) in the human colon cancer cell line HCT116 and green-fluorescent protein (GFP) in human embryonic kidney 293T cells stably expressing GFP. Notably, we confirmed that the transporter PA can be adapted to recognize specific host cell-surface receptor proteins and may be optimized for cell type-selective delivery of Cas9. Altogether, CRISPA provides a novel, transient and non-viral way to deliver Cas9 into specific cells. Thus, this system is an additional step towards safe translation of the CRISPR/Cas9 technology into clinics.
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Affiliation(s)
- Maximilian Hirschenberger
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany.,Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Nicole Stadler
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Maximilian Fellermann
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | | | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
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17
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Ernst K, Landenberger M, Nieland J, Nørgaard K, Frick M, Fois G, Benz R, Barth H. Characterization and Pharmacological Inhibition of the Pore-Forming Clostridioides difficile CDTb Toxin. Toxins (Basel) 2021; 13:toxins13060390. [PMID: 34071730 PMCID: PMC8226936 DOI: 10.3390/toxins13060390] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 12/18/2022] Open
Abstract
The clinically highly relevant Clostridioides (C.) difficile releases several AB-type toxins that cause diseases such as diarrhea and pseudomembranous colitis. In addition to the main virulence factors Rho/Ras-glycosylating toxins TcdA and TcdB, hypervirulent strains produce the binary AB-type toxin CDT. CDT consists of two separate proteins. The binding/translocation B-component CDTb facilitates uptake and translocation of the enzyme A-component CDTa to the cytosol of cells. Here, CDTa ADP-ribosylates G-actin, resulting in depolymerization of the actin cytoskeleton. We previously showed that CDTb exhibits cytotoxicity in the absence of CDTa, which is most likely due to pore formation in the cytoplasmic membrane. Here, we further investigated this cytotoxic effect and showed that CDTb impairs CaCo-2 cell viability and leads to redistribution of F-actin without affecting tubulin structures. CDTb was detected at the cytoplasmic membrane in addition to its endosomal localization if CDTb was applied alone. Chloroquine and several of its derivatives, which were previously identified as toxin pore blockers, inhibited intoxication of Vero, HCT116, and CaCo-2 cells by CDTb and CDTb pores in vitro. These results further strengthen pore formation by CDTb in the cytoplasmic membrane as the underlying cytotoxic mechanism and identify pharmacological pore blockers as potent inhibitors of cytotoxicity induced by CDTb and CDTa plus CDTb.
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Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
- Correspondence: (K.E.); (H.B.)
| | - Marc Landenberger
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
| | - Julian Nieland
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
| | - Katharina Nørgaard
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
| | - Manfred Frick
- Institute of General Physiology, Ulm University, 89081 Ulm, Germany; (M.F.); (G.F.)
| | - Giorgio Fois
- Institute of General Physiology, Ulm University, 89081 Ulm, Germany; (M.F.); (G.F.)
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs-University Bremen, 28759 Bremen, Germany;
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
- Correspondence: (K.E.); (H.B.)
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18
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Voegele A, Sadi M, O'Brien DP, Gehan P, Raoux‐Barbot D, Davi M, Hoos S, Brûlé S, Raynal B, Weber P, Mechaly A, Haouz A, Rodriguez N, Vachette P, Durand D, Brier S, Ladant D, Chenal A. A High-Affinity Calmodulin-Binding Site in the CyaA Toxin Translocation Domain is Essential for Invasion of Eukaryotic Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2003630. [PMID: 33977052 PMCID: PMC8097335 DOI: 10.1002/advs.202003630] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/10/2020] [Indexed: 06/12/2023]
Abstract
The molecular mechanisms and forces involved in the translocation of bacterial toxins into host cells are still a matter of intense research. The adenylate cyclase (CyaA) toxin from Bordetella pertussis displays a unique intoxication pathway in which its catalytic domain is directly translocated across target cell membranes. The CyaA translocation region contains a segment, P454 (residues 454-484), which exhibits membrane-active properties related to antimicrobial peptides. Herein, the results show that this peptide is able to translocate across membranes and to interact with calmodulin (CaM). Structural and biophysical analyses reveal the key residues of P454 involved in membrane destabilization and calmodulin binding. Mutational analysis demonstrates that these residues play a crucial role in CyaA translocation into target cells. In addition, calmidazolium, a calmodulin inhibitor, efficiently blocks CyaA internalization. It is proposed that after CyaA binding to target cells, the P454 segment destabilizes the plasma membrane, translocates across the lipid bilayer and binds calmodulin. Trapping of CyaA by the CaM:P454 interaction in the cytosol may assist the entry of the N-terminal catalytic domain by converting the stochastic motion of the polypeptide chain through the membrane into an efficient vectorial chain translocation into host cells.
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Affiliation(s)
- Alexis Voegele
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
- Université de ParisSorbonne Paris CitéParis75006France
| | - Mirko Sadi
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
- Université de ParisSorbonne Paris CitéParis75006France
| | - Darragh Patrick O'Brien
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Pauline Gehan
- Sorbonne UniversitéÉcole normale supérieurePSL UniversityCNRSLaboratoire des biomoléculesLBMParis75005France
| | - Dorothée Raoux‐Barbot
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Maryline Davi
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Sylviane Hoos
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Sébastien Brûlé
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Bertrand Raynal
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Patrick Weber
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Ariel Mechaly
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Ahmed Haouz
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Nicolas Rodriguez
- Sorbonne UniversitéÉcole normale supérieurePSL UniversityCNRSLaboratoire des biomoléculesLBMParis75005France
| | - Patrice Vachette
- Université Paris‐SaclayCEACNRSInstitute for Integrative Biology of the Cell (I2BC)Gif‐sur‐Yvette91198France
| | - Dominique Durand
- Université Paris‐SaclayCEACNRSInstitute for Integrative Biology of the Cell (I2BC)Gif‐sur‐Yvette91198France
| | - Sébastien Brier
- Biological NMR Technological PlateformCenter for Technological Resources and ResearchDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Daniel Ladant
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Alexandre Chenal
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
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19
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Ernst K, Mittler AK, Winkelmann V, Kling C, Eberhardt N, Anastasia A, Sonnabend M, Lochbaum R, Wirsching J, Sakari M, Pulliainen AT, Skerry C, Carbonetti NH, Frick M, Barth H. Pharmacological targeting of host chaperones protects from pertussis toxin in vitro and in vivo. Sci Rep 2021; 11:5429. [PMID: 33686161 PMCID: PMC7940712 DOI: 10.1038/s41598-021-84817-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 02/16/2021] [Indexed: 01/05/2023] Open
Abstract
Whooping cough is caused by Bordetella pertussis that releases pertussis toxin (PT) which comprises enzyme A-subunit PTS1 and binding/transport B-subunit. After receptor-mediated endocytosis, PT reaches the endoplasmic reticulum from where unfolded PTS1 is transported to the cytosol. PTS1 ADP-ribosylates G-protein α-subunits resulting in increased cAMP signaling. Here, a role of target cell chaperones Hsp90, Hsp70, cyclophilins and FK506-binding proteins for cytosolic PTS1-uptake is demonstrated. PTS1 specifically and directly interacts with chaperones in vitro and in cells. Specific pharmacological chaperone inhibition protects CHO-K1, human primary airway basal cells and a fully differentiated airway epithelium from PT-intoxication by reducing intracellular PTS1-amounts without affecting cell binding or enzyme activity. PT is internalized by human airway epithelium secretory but not ciliated cells and leads to increase of apical surface liquid. Cyclophilin-inhibitors reduced leukocytosis in infant mouse model of pertussis, indicating their promising potential for developing novel therapeutic strategies against whooping cough.
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Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany.
| | - Ann-Katrin Mittler
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | | | - Carolin Kling
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Nina Eberhardt
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Anna Anastasia
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Michael Sonnabend
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Robin Lochbaum
- Institute of General Physiology, University of Ulm, Ulm, Germany
| | - Jan Wirsching
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Moona Sakari
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Turku, Finland
| | - Arto T Pulliainen
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Turku, Finland
| | - Ciaran Skerry
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Nicholas H Carbonetti
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Manfred Frick
- Institute of General Physiology, University of Ulm, Ulm, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany.
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20
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Landenberger M, Nieland J, Roeder M, Nørgaard K, Papatheodorou P, Ernst K, Barth H. The cytotoxic effect of Clostridioides difficile pore-forming toxin CDTb. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183603. [PMID: 33689753 DOI: 10.1016/j.bbamem.2021.183603] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 01/05/2023]
Abstract
Clostridioides (C.) difficile is clinically highly relevant and produces several AB-type protein toxins, which are the causative agents for C. difficile-associated diarrhea and pseudomembranous colitis. Treatment with antibiotics can lead to C. difficile overgrowth in the gut of patients due to the disturbed microbiota. C. difficile releases large Rho/Ras-GTPase glucosylating toxins TcdA and TcdB, which are considered as the major virulence factors for C. difficile-associated diseases. In addition to TcdA and TcdB, C. difficile strains isolated from severe cases of colitis produce a third toxin called CDT. CDT is a member of the family of clostridial binary actin ADP-ribosylating toxins and consists of two separate protein components. The B-component, CDTb, binds to the receptor and forms a complex with and facilitates transport and translocation of the enzymatically active A-component, CDTa, into the cytosol of target cells by forming trans-membrane pores through which CDTa translocates. In the cytosol, CDTa ADP-ribosylates G-actin causing depolymerization of the actin cytoskeleton and, eventually, cell death. In the present study, we report that CDTb exhibits a cytotoxic effect in the absence of CDTa. We show that CDTb causes cell rounding and impairs cell viability and the epithelial integrity of CaCo-2 monolayers in the absence of CDTa. CDTb-induced cell rounding depended on the presence of LSR, the specific cellular receptor of CDT. The isolated receptor-binding domain of CDTb was not sufficient to cause cell rounding. CDTb-induced cell rounding was inhibited by enzymatically inactive CDTa or a pore-blocker, implying that CDTb pores in cytoplasmic membranes contribute to cytotoxicity.
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Affiliation(s)
- Marc Landenberger
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Julian Nieland
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Maurice Roeder
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Katharina Nørgaard
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | | | - Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
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21
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Liao Y, Luo D, Peng K, Zeng Y. Cyclophilin A: a key player for etiological agent infection. Appl Microbiol Biotechnol 2021; 105:1365-1377. [PMID: 33492451 PMCID: PMC7829623 DOI: 10.1007/s00253-021-11115-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 01/07/2021] [Accepted: 01/13/2021] [Indexed: 12/13/2022]
Abstract
Abstract Cyclophilin A (CypA), a key member of the immunophilin family, is the most abundantly expressed isozyme of the 18 known human cyclophilins. Besides acting as an intracellular receptor for cyclosporine A, CypA plays a vital role in microorganismal infections, cardiovascular diseases, liver diseases, kidney diseases, neurodegeneration, cancer, rheumatoid arthritis, periodontitis, sepsis, asthma, and aging. This review focuses on the pivotal roles of CypA in the infection of etiological agents, which manifests mainly in promoting or inhibiting viral replication based on the host cell type and viral species. CypA can interact with viral proteins and thus regulate the replication cycle of the virus. CypA is involved in pathogenic bacterial infections by regulating the formation of host actin skeleton or membrane translocation of bacterial toxins, or mediated the adhesion of Mycoplasma genitalium during the infection processes by acting as a cellular receptor of M. genitalium. CypA also plays a critical role in infection or the life cycle of certain parasites or host immune regulation. Moreover, we summarized the current understanding of CypA inhibitors acting as host-targeting antiviral agents, thus opening an avenue for the treatment of multiple viral infections due to their broad antiviral effects and ability to effectively prevent drug resistance. Therefore, the antiviral effect of CypA has the potential to promote CypA inhibitors as host-targeting drugs to CypA-involved etiological agent infections and human diseases. Key points • CypA is involved in the replication and infection of several viruses, pathogenic bacteria, mycoplasma, and parasites. • CypA inhibitors are in a strong position to inhibit the infection of viruses, bacterial, and mycoplasma.
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Affiliation(s)
- Yating Liao
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, No. 28, West Changsheng Road, Hengyang City, 421001 Hunan Province People’s Republic of China
| | - Dan Luo
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, No. 28, West Changsheng Road, Hengyang City, 421001 Hunan Province People’s Republic of China
| | - Kailan Peng
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, No. 28, West Changsheng Road, Hengyang City, 421001 Hunan Province People’s Republic of China
| | - Yanhua Zeng
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, No. 28, West Changsheng Road, Hengyang City, 421001 Hunan Province People’s Republic of China
- Department of Dermatology and Venereology, The First Affiliated Hospital, University of South China, Hengyang City, 421001 Hunan Province People’s Republic of China
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22
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Ernst K, Sailer J, Braune M, Barth H. Intoxication of mammalian cells with binary clostridial enterotoxins is inhibited by the combination of pharmacological chaperone inhibitors. Naunyn Schmiedebergs Arch Pharmacol 2020; 394:941-954. [PMID: 33284399 PMCID: PMC8102464 DOI: 10.1007/s00210-020-02029-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 11/18/2020] [Indexed: 01/05/2023]
Abstract
Binary enterotoxins Clostridioides difficile CDT toxin, Clostridium botulinum C2 toxin, and Clostridium perfringens iota toxin consist of two separate protein components. The B-components facilitate receptor-mediated uptake into mammalian cells and form pores into endosomal membranes through which the enzymatic active A-components translocate into the cytosol. Here, the A-components ADP-ribosylate G-actin which leads to F-actin depolymerization followed by rounding of cells which causes clinical symptoms. The protein folding helper enzymes Hsp90, Hsp70, and peptidyl-prolyl cis/trans isomerases of the cyclophilin (Cyp) and FK506 binding protein (FKBP) families are required for translocation of A-components of CDT, C2, and iota toxins from endosomes to the cytosol. Here, we demonstrated that simultaneous inhibition of these folding helpers by specific pharmacological inhibitors protects mammalian, including human, cells from intoxication with CDT, C2, and iota toxins, and that the inhibitor combination displayed an enhanced effect compared to application of the individual inhibitors. Moreover, combination of inhibitors allowed a concentration reduction of the individual compounds as well as decreasing of the incubation time with inhibitors to achieve a protective effect. These results potentially have implications for possible future therapeutic applications to relieve clinical symptoms caused by bacterial toxins that depend on Hsp90, Hsp70, Cyps, and FKBPs for their membrane translocation into the cytosol of target cells.
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Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081, Ulm, Germany.
| | - Judith Sailer
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081, Ulm, Germany
| | - Maria Braune
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081, Ulm, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081, Ulm, Germany.
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Schwartz R, Guichard A, Franc NC, Roy S, Bier E. A Drosophila Model for Clostridium difficile Toxin CDT Reveals Interactions with Multiple Effector Pathways. iScience 2020; 23:100865. [PMID: 32058973 PMCID: PMC7011083 DOI: 10.1016/j.isci.2020.100865] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 12/05/2019] [Accepted: 01/17/2020] [Indexed: 12/11/2022] Open
Abstract
Clostridium difficile infections (CDIs) cause severe and occasionally life-threatening diarrhea. Hyper-virulent strains produce CDT, a toxin that ADP-ribosylates actin monomers and inhibits actin polymerization. We created transgenic Drosophila lines expressing the catalytic subunit CDTa to investigate its interaction with host signaling pathways in vivo. When expressed in the midgut, CDTa reduces body weight and fecal output and compromises survival, suggesting severe impairment of digestive functions. At the cellular level, CDTa induces F-actin network collapse, elimination of the intestinal brush border, and disruption of intercellular junctions. We confirm toxin-dependent re-distribution of Rab11 to enterocytes' apical surface and observe suppression of CDTa phenotypes by a Dominant-Negative form of Rab11 or RNAi of the dedicated Rab11GEF Crag (DENND4). We also report that Calmodulin (Cam) is required to mediate CDTa activity. In parallel, chemical inhibition of the Cam/Calcineurin pathway by Cyclosporin A or FK506 also reduces CDTa phenotypes, potentially opening new avenues for treating CDIs.
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Affiliation(s)
- Ruth Schwartz
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0335, USA
| | - Annabel Guichard
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0335, USA; Tata Institute for Genetics and Society-UCSD, La Jolla, CA 92093-0335, USA
| | - Nathalie C Franc
- Franc Consulting, San Diego, CA 92117-3314, USA; The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sitara Roy
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0335, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0335, USA; Tata Institute for Genetics and Society-UCSD, La Jolla, CA 92093-0335, USA.
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24
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Anderson DM, Sheedlo MJ, Jensen JL, Lacy DB. Structural insights into the transition of Clostridioides difficile binary toxin from prepore to pore. Nat Microbiol 2020; 5:102-107. [PMID: 31712627 PMCID: PMC6925320 DOI: 10.1038/s41564-019-0601-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 10/03/2019] [Indexed: 11/28/2022]
Abstract
Clostridioides (formerly Clostridium) difficile is a Gram-positive, spore-forming anaerobe and a leading cause of hospital-acquired infection and gastroenteritis-associated death in US hospitals1. The disease state is usually preceded by disruption of the host microbiome in response to antibiotic treatment and is characterized by mild to severe diarrhoea. C. difficile infection is dependent on the secretion of one or more AB-type toxins: toxin A (TcdA), toxin B (TcdB) and the C. difficile transferase toxin (CDT)2. Whereas TcdA and TcdB are considered the primary virulence factors, recent studies suggest that CDT increases the severity of C. difficile infection in some of the most problematic clinical strains3. To better understand how CDT functions, we used cryo-electron microscopy to define the structure of CDTb, the cell-binding component of CDT. We obtained structures of several oligomeric forms that highlight the conformational changes that enable conversion from a prepore to a β-barrel pore. The structural analysis also reveals a glycan-binding domain and residues involved in binding the host-cell receptor, lipolysis-stimulated lipoprotein receptor. Together, these results provide a framework to understand how CDT functions at the host cell interface.
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Affiliation(s)
- David M Anderson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Michael J Sheedlo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Jaime L Jensen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - D Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.
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25
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Kellner A, Taylor M, Banerjee T, Britt CB, Teter K. A binding motif for Hsp90 in the A chains of ADP-ribosylating toxins that move from the endoplasmic reticulum to the cytosol. Cell Microbiol 2019; 21:e13074. [PMID: 31231933 PMCID: PMC6744307 DOI: 10.1111/cmi.13074] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/15/2019] [Accepted: 06/19/2019] [Indexed: 12/29/2022]
Abstract
Cholera toxin (Ctx) is an AB-type protein toxin that acts as an adenosine diphosphate (ADP)-ribosyltransferase to disrupt intracellular signalling in the target cell. It moves by vesicle carriers from the cell surface to the endoplasmic reticulum (ER) of an intoxicated cell. The catalytic CtxA1 subunit then dissociates from the rest of the toxin, unfolds, and activates the ER-associated degradation system for export to the cytosol. Translocation occurs through an unusual ratchet mechanism in which the cytosolic chaperone Hsp90 couples CtxA1 refolding with CtxA1 extraction from the ER. Here, we report that Hsp90 recognises two peptide sequences from CtxA1: an N-terminal RPPDEI sequence (residues 11-16) and an LDIAPA sequence in the C-terminal region (residues 153-158) of the 192 amino acid protein. Peptides containing either sequence effectively blocked Hsp90 binding to full-length CtxA1. Both sequences were necessary for the ER-to-cytosol export of CtxA1. Mutagenesis studies further demonstrated that the RPP residues in the RPPDEI motif are required for CtxA1 translocation to the cytosol. The LDIAPA sequence is unique to CtxA1, but we identified an RPPDEI-like motif at the N- or C-termini of the A chains from four other ER-translocating toxins that act as ADP-ribosyltransferases: pertussis toxin, Escherichia coli heat-labile toxin, Pseudomonas aeruginosa exotoxin A, and Salmonella enterica serovar Typhimurium ADP-ribosylating toxin. Hsp90 plays a functional role in the intoxication process for most, if not all, of these toxins. Our work has established a defined RPPDEI binding motif for Hsp90 that is required for the ER-to-cytosol export of CtxA1 and possibly other toxin A chains as well.
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Affiliation(s)
- Alisha Kellner
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32826
| | - Michael Taylor
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32826
| | | | - Christopher B.T. Britt
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32826
| | - Ken Teter
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32826
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26
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Stiles BG. Clostridial Binary Toxins: Basic Understandings that Include Cell Surface Binding and an Internal "Coup de Grâce". Curr Top Microbiol Immunol 2019; 406:135-162. [PMID: 27380267 DOI: 10.1007/82_2016_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Clostridium species can make a remarkable number of different protein toxins, causing many diverse diseases in humans and animals. The binary toxins of Clostridium botulinum, C. difficile, C. perfringens, and C. spiroforme are one group of enteric-acting toxins that attack the actin cytoskeleton of various cell types. These enterotoxins consist of A (enzymatic) and B (cell binding/membrane translocation) components that assemble on the targeted cell surface or in solution, forming a multimeric complex. Once translocated into the cytosol via endosomal trafficking and acidification, the A component dismantles the filamentous actin-based cytoskeleton via mono-ADP-ribosylation of globular actin. Knowledge of cell surface receptors and how these usurped, host-derived molecules facilitate intoxication can lead to novel ways of defending against these clostridial binary toxins. A molecular-based understanding of the various steps involved in toxin internalization can also unveil therapeutic intervention points that stop the intoxication process. Furthermore, using these bacterial proteins as medicinal shuttle systems into cells provides intriguing possibilities in the future. The pertinent past and state-of-the-art present, regarding clostridial binary toxins, will be evident in this chapter.
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Affiliation(s)
- Bradley G Stiles
- Biology Department, Wilson College, Chambersburg, PA, 17201, USA.
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27
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Receptor-Binding and Uptake of Binary Actin-ADP-Ribosylating Toxins. Curr Top Microbiol Immunol 2019; 406:119-133. [PMID: 27817176 DOI: 10.1007/82_2016_46] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Binary actin-ADP-ribosylating toxins (e.g., Clostridium botulinum C2 toxin or Clostridium perfringens iota toxin ) consist of two separate proteins: An ADP-ribosyltransferase, which modifies actin thereby inhibiting actin polymerization, and a binding component that forms heptamers after proteolytic activation. While C2 toxin interacts with carbohydrate structures on host cells, the group of iota-like toxins binds to lipolysis-stimulated lipoprotein receptor (LSR). Here, we review LSR and discuss the role and function of LSR in interaction of iota-like toxins with host cells.
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28
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Rodrigues IS, Pereira LMG, Lisboa J, Pereira C, Oliveira P, Dos Santos NMS, do Vale A. Involvement of Hsp90 and cyclophilins in intoxication by AIP56, a metalloprotease toxin from Photobacterium damselae subsp. piscicida. Sci Rep 2019; 9:9019. [PMID: 31227743 PMCID: PMC6588550 DOI: 10.1038/s41598-019-45240-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 06/03/2019] [Indexed: 12/28/2022] Open
Abstract
AIP56 (apoptosis inducing protein of 56 kDa) is a key virulence factor secreted by virulent strains of Photobacterium damselae subsp. piscicida (Phdp), a Gram-negative bacterium that causes septicemic infections in several warm water marine fish species. AIP56 is systemically disseminated during infection and induces massive apoptosis of host macrophages and neutrophils, playing a decisive role in the disease outcome. AIP56 is a single-chain AB-type toxin, being composed by a metalloprotease A domain located at the N-terminal region connected to a C-terminal B domain, required for internalization of the toxin into susceptible cells. After binding to a still unidentified surface receptor, AIP56 is internalised through clathrin-mediated endocytosis, reaches early endosomes and translocates into the cytosol through a mechanism requiring endosomal acidification and involving low pH-induced unfolding of the toxin. At the cytosol, the catalytic domain of AIP56 cleaves NF-κB p65, leading to the apoptotic death of the intoxicated cells. It has been reported that host cytosolic factors, including host cell chaperones such as heat shock protein 90 (Hsp90) and peptidyl-prolyl cis/trans isomerases (PPIases), namely cyclophilin A/D (Cyp) and FK506-binding proteins (FKBP) are involved in the uptake of several bacterial AB toxins with ADP-ribosylating activity, but are dispensable for the uptake of other AB toxins with different enzymatic activities, such as Bacillus anthracis lethal toxin (a metalloprotease) or the large glycosylating toxins A and B of Clostridium difficile. Based on these findings, it has been proposed that the requirement for Hsp90/PPIases is a common and specific characteristic of ADP-ribosylating toxins. In the present work, we demonstrate that Hsp90 and the PPIases cyclophilin A/D are required for efficient intoxication by the metalloprotease toxin AIP56. We further show that those host cell factors interact with AIP56 in vitro and that the interactions increase when AIP56 is unfolded. The interaction with Hsp90 was also demonstrated in intact cells, at 30 min post-treatment with AIP56, suggesting that it occurs during or shortly after translocation of the toxin from endosomes into the cytosol. Based on these findings, we propose that the participation of Hsp90 and Cyp in bacterial toxin entry may be more disseminated than initially expected, and may include toxins with different catalytic activities.
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Affiliation(s)
- Inês S Rodrigues
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Liliana M G Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Johnny Lisboa
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Cassilda Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Pedro Oliveira
- EPIUnit, ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Nuno M S Dos Santos
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Ana do Vale
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
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29
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Burress H, Kellner A, Guyette J, Tatulian SA, Teter K. HSC70 and HSP90 chaperones perform complementary roles in translocation of the cholera toxin A1 subunit from the endoplasmic reticulum to the cytosol. J Biol Chem 2019; 294:12122-12131. [PMID: 31221799 DOI: 10.1074/jbc.ra119.008568] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/15/2019] [Indexed: 11/06/2022] Open
Abstract
Cholera toxin (CT) travels by vesicle carriers from the cell surface to the endoplasmic reticulum (ER) where the catalytic A1 subunit of CT (CTA1) dissociates from the rest of the toxin, unfolds, and moves through a membrane-spanning translocon pore to reach the cytosol. Heat shock protein 90 (HSP90) binds to the N-terminal region of CTA1 and facilitates its ER-to-cytosol export by refolding the toxin as it emerges at the cytosolic face of the ER membrane. HSP90 also refolds some endogenous cytosolic proteins as part of a foldosome complex containing heat shock cognate 71-kDa protein (HSC70) and the HSC70/HSP90-organizing protein (HOP) linker that anchors HSP90 to HSC70. We accordingly predicted that HSC70 and HOP also function in CTA1 translocation. Inactivation of HSC70 by drug treatment disrupted CTA1 translocation to the cytosol and generated a toxin-resistant phenotype. In contrast, the depletion of HOP did not disrupt CT activity against cultured cells. HSC70 and HSP90 could bind independently to disordered CTA1, even in the absence of HOP. This indicated HSP90 and HSC70 recognize distinct regions of CTA1, which was confirmed by the identification of a YYIYVI-binding motif for HSC70 that spans residues 83-88 of the 192-amino acid CTA1 polypeptide. Refolding of disordered CTA1 occurred in the presence of HSC70 alone, indicating that HSC70 and HSP90 can each independently refold CTA1. Our work suggests a novel translocation mechanism in which sequential interactions with HSP90 and HSC70 drive the N- to C-terminal extraction of CTA1 from the ER.
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Affiliation(s)
- Helen Burress
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32826
| | - Alisha Kellner
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32826
| | - Jessica Guyette
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32826
| | - Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, Florida 32816
| | - Ken Teter
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32826.
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30
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Kumar R, Feltrup TM, Kukreja RV, Patel KB, Cai S, Singh BR. Evolutionary Features in the Structure and Function of Bacterial Toxins. Toxins (Basel) 2019; 11:toxins11010015. [PMID: 30609803 PMCID: PMC6356308 DOI: 10.3390/toxins11010015] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/24/2018] [Accepted: 12/25/2018] [Indexed: 12/21/2022] Open
Abstract
Toxins can function both as a harmful and therapeutic molecule, depending on their concentrations. The diversity in their function allows us to ask some very pertinent questions related to their origin and roles: (a) What makes them such effective molecules? (b) Are there evolutionary features encoded within the structures of the toxins for their function? (c) Is structural hierarchy in the toxins important for maintaining their structure and function? (d) Do protein dynamics play a role in the function of toxins? and (e) Do the evolutionary connections to these unique features and functions provide the fundamental points in driving evolution? In light of the growing evidence in structural biology, it would be appropriate to suggest that protein dynamics and flexibility play a much bigger role in the function of the toxin than the structure itself. Discovery of IDPs (intrinsically disorder proteins), multifunctionality, and the concept of native aggregation are shaking the paradigm of the requirement of a fixed three-dimensional structure for the protein’s function. Growing evidence supporting the above concepts allow us to redesign the structure-function aspects of the protein molecules. An evolutionary model is necessary and needs to be developed to study these important aspects. The criteria for a well-defined model would be: (a) diversity in structure and function, (b) unique functionality, and (c) must belong to a family to define the evolutionary relationships. All these characteristics are largely fulfilled by bacterial toxins. Bacterial toxins are diverse and widely distributed in all three forms of life (Bacteria, Archaea and Eukaryotes). Some of the unique characteristics include structural folding, sequence and functional combination of domains, targeting a cellular process to execute their function, and most importantly their flexibility and dynamics. In this work, we summarize certain unique aspects of bacterial toxins, including role of structure in defining toxin function, uniqueness in their enzymatic function, and interaction with their substrates and other proteins. Finally, we have discussed the evolutionary aspects of toxins in detail, which will help us rethink the current evolutionary theories. A careful study, and appropriate interpretations, will provide answers to several questions related to the structure-function relationship of proteins, in general. Additionally, this will also allow us to refine the current evolution theories.
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Affiliation(s)
- Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Thomas M Feltrup
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Roshan V Kukreja
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Kruti B Patel
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Shuowei Cai
- Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, MA 02747, USA.
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
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31
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Ernst K, Kling C, Landenberger M, Barth H. Combined Pharmacological Inhibition of Cyclophilins, FK506-Binding Proteins, Hsp90, and Hsp70 Protects Cells From Clostridium botulinum C2 Toxin. Front Pharmacol 2018; 9:1287. [PMID: 30483129 PMCID: PMC6243138 DOI: 10.3389/fphar.2018.01287] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/22/2018] [Indexed: 12/19/2022] Open
Abstract
The Clostridium botulinum C2 toxin is an exotoxin causing severe enterotoxic symptoms. The C2 toxin consists of the binding/translocation component C2II, and the enzymatic active component C2I. After proteolytic activation, C2IIa forms heptamers that bind C2I. The C2IIa/C2I complex is taken up into mammalian target cells via receptor-mediated endocytosis. Acidification of endosomes leads to conformational changes in both components. C2IIa heptamers form a pore into the endosomal membrane, and C2I becomes unfolded and translocates through the narrow C2IIa pores into the cytosol of the cell. Here, C2I covalently transfers an ADP-ribose moiety from its co-substrate NAD+ onto G-actin, which leads to depolymerization of F-actin resulting in rounding up of adherent cells. Translocation of C2I into the cytosol depends on the activity of the chaperones Hsp90 and Hsp70 and peptidyl-prolyl cis/trans isomerases of the cyclophilin (Cyp) and FK506-binding protein (FKBP) families. Here, we demonstrated that C2I is detected in close proximity with Hsp90, Cyp40, and FKBP51 in cells, indicating their interaction. This interaction was dependent on the concentration of C2 toxin and detected in mammalian Vero and human HeLa cells. Moreover, the present study reveals that combination of radicicol, VER-155008, cyclosporine A, and FK506, which are specific pharmacological inhibitors of Hsp90, Hsp70, Cyps, and FKBPs, respectively, resulted in a stronger inhibition of intoxication of cells with C2 toxin compared to application of the single inhibitors. Thus, the combination of inhibitors showed enhanced protection of cells against the cytotoxic effects of C2 toxin. Cell viability was not significantly impaired by application of the inhibitor combination. Moreover, we confirmed that the combination of radicicol, VER-155008, CsA, and FK506 in particular inhibit the membrane translocation step of C2I into the cytosol whereas receptor binding and enzyme activity of the toxin were not affected. Our findings further characterize the mode of action of Hsp90, Hsp70, Cyps, and FKBPs during membrane translocation of bacterial toxins and furthermore supply starting points for developing of novel therapeutic strategies against diseases caused by bacterial toxins that depend on Hsp90, Hsp70, Cyps, and FKBPs.
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Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Carolin Kling
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Marc Landenberger
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
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32
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Pharmacological Cyclophilin Inhibitors Prevent Intoxication of Mammalian Cells with Bordetella pertussis Toxin. Toxins (Basel) 2018; 10:toxins10050181. [PMID: 29723951 PMCID: PMC5983237 DOI: 10.3390/toxins10050181] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/18/2018] [Accepted: 04/23/2018] [Indexed: 11/17/2022] Open
Abstract
The Bordetella pertussis toxin (PT) is one important virulence factor causing the severe childhood disease whooping cough which still accounted for approximately 63,000 deaths worldwide in children in 2013. PT consists of PTS1, the enzymatically active (A) subunit and a non-covalently linked pentameric binding/transport (B) subunit. After endocytosis, PT takes a retrograde route to the endoplasmic reticulum (ER), where PTS1 is released into the cytosol. In the cytosol, PTS1 ADP-ribosylates inhibitory alpha subunits of trimeric GTP-binding proteins (Giα) leading to increased cAMP levels and disturbed signalling. Here, we show that the cyclophilin (Cyp) isoforms CypA and Cyp40 directly interact with PTS1 in vitro and that Cyp inhibitors cyclosporine A (CsA) and its tailored non-immunosuppressive derivative VK112 both inhibit intoxication of CHO-K1 cells with PT, as analysed in a morphology-based assay. Moreover, in cells treated with PT in the presence of CsA, the amount of ADP-ribosylated Giα was significantly reduced and less PTS1 was detected in the cytosol compared to cells treated with PT only. The results suggest that the uptake of PTS1 into the cytosol requires Cyps. Therefore, CsA/VK112 represent promising candidates for novel therapeutic strategies acting on the toxin level to prevent the severe, life-threatening symptoms caused by PT.
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33
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Aktories K, Papatheodorou P, Schwan C. Binary Clostridium difficile toxin (CDT) - A virulence factor disturbing the cytoskeleton. Anaerobe 2018. [PMID: 29524654 DOI: 10.1016/j.anaerobe.2018.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Clostridium difficile infection causes antibiotics-associated diarrhea and pseudomembranous colitis. Major virulence factors of C. difficile are the Rho-glucosylating toxins TcdA and TcdB. In addition, many, so-called hypervirulent C. difficile strains produce the binary actin-ADP-ribosylating toxin CDT. CDT causes depolymerization of F-actin and rearrangement of the actin cytoskeleton. Thereby, many cellular functions, which depend on actin, are altered. CDT disturbs the dynamic balance between actin and microtubules in target cells. The toxin increases microtubule polymerization and induces the formation of microtubule-based protrusions at the plasma membrane of target cells. Moreover, CDT causes a redistribution of vesicles from the basolateral side to the apical side, where extracellular matrix proteins are released. These processes may increase the adherence of clostridia to target cells. Here, we review the effects of the action of CDT on the actin cytoskeleton and on the microtubule system.
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Affiliation(s)
- Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Albertstr. 25, 79104 Freiburg, Germany; Centre for Biological Signalling Studies (BIOSS), University of Freiburg, 79104 Freiburg, Germany.
| | - Panagiotis Papatheodorou
- Faculty of Natural Sciences, University of Ulm, 89081 Ulm, Germany; Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Albertstr. 25, 79104 Freiburg, Germany
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Cellular Uptake and Mode-of-Action of Clostridium difficile Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1050:77-96. [DOI: 10.1007/978-3-319-72799-8_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Chandrasekaran R, Lacy DB. The role of toxins in Clostridium difficile infection. FEMS Microbiol Rev 2017; 41:723-750. [PMID: 29048477 PMCID: PMC5812492 DOI: 10.1093/femsre/fux048] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 10/10/2017] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile is a bacterial pathogen that is the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. The incidence, severity, mortality and healthcare costs associated with C. difficile infection (CDI) are rising, making C. difficile a major threat to public health. Traditional treatments for CDI involve use of antibiotics such as metronidazole and vancomycin, but disease recurrence occurs in about 30% of patients, highlighting the need for new therapies. The pathogenesis of C. difficile is primarily mediated by the actions of two large clostridial glucosylating toxins, toxin A (TcdA) and toxin B (TcdB). Some strains produce a third toxin, the binary toxin C. difficile transferase, which can also contribute to C. difficile virulence and disease. These toxins act on the colonic epithelium and immune cells and induce a complex cascade of cellular events that result in fluid secretion, inflammation and tissue damage, which are the hallmark features of the disease. In this review, we summarize our current understanding of the structure and mechanism of action of the C. difficile toxins and their role in disease.
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Affiliation(s)
- Ramyavardhanee Chandrasekaran
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37232, USA
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Aktories K, Schwan C, Lang AE. ADP-Ribosylation and Cross-Linking of Actin by Bacterial Protein Toxins. Handb Exp Pharmacol 2017; 235:179-206. [PMID: 27316913 DOI: 10.1007/164_2016_26] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Actin and the actin cytoskeleton play fundamental roles in host-pathogen interactions. Proper function of the actin cytoskeleton is crucial for innate and acquired immune defense. Bacterial toxins attack the actin cytoskeleton by targeting regulators of actin. Moreover, actin is directly modified by various bacterial protein toxins and effectors, which cause ADP-ribosylation or cross-linking of actin. Modification of actin can result in inhibition or stimulation of actin polymerization. Toxins, acting directly on actin, are reviewed.
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Affiliation(s)
- Klaus Aktories
- Institute for Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany. .,Freiburg Institute of Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany.
| | - Carsten Schwan
- Institute for Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany
| | - Alexander E Lang
- Institute for Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany
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Takehara M, Takagishi T, Seike S, Oda M, Sakaguchi Y, Hisatsune J, Ochi S, Kobayashi K, Nagahama M. Cellular Entry of Clostridium perfringens Iota-Toxin and Clostridium botulinum C2 Toxin. Toxins (Basel) 2017; 9:toxins9080247. [PMID: 28800062 PMCID: PMC5577581 DOI: 10.3390/toxins9080247] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 07/31/2017] [Accepted: 08/09/2017] [Indexed: 12/05/2022] Open
Abstract
Clostridium perfringens iota-toxin and Clostridium botulinum C2 toxin are composed of two non-linked proteins, one being the enzymatic component and the other being the binding/translocation component. These latter components recognize specific receptors and oligomerize in plasma membrane lipid-rafts, mediating the uptake of the enzymatic component into the cytosol. Enzymatic components induce actin cytoskeleton disorganization through the ADP-ribosylation of actin and are responsible for cell rounding and death. This review focuses upon the recent advances in cellular internalization of clostridial binary toxins.
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Affiliation(s)
- Masaya Takehara
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Teruhisa Takagishi
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Soshi Seike
- Laboratory of Molecular Microbiological Science, Faculty of Pharmaceutical Sciences, Hiroshima International University, Kure, Hiroshima 737-0112, Japan.
| | - Masataka Oda
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan.
| | - Yoshihiko Sakaguchi
- Department of Microbiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0374, Japan.
| | - Junzo Hisatsune
- Department of Bacteriology, Graduate school of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
| | - Sadayuki Ochi
- Faculty of Pharmacy, Yokohama University of Pharmacy, 601 Matano-cho, Totsuka-ku, Yokohama-shi, Kanagawa 245-0066, Japan.
| | - Keiko Kobayashi
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
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Hsp70 facilitates trans-membrane transport of bacterial ADP-ribosylating toxins into the cytosol of mammalian cells. Sci Rep 2017; 7:2724. [PMID: 28578412 PMCID: PMC5457432 DOI: 10.1038/s41598-017-02882-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 04/19/2017] [Indexed: 12/19/2022] Open
Abstract
Binary enterotoxins Clostridium (C.) botulinum C2 toxin, C. perfringens iota toxin and C. difficile toxin CDT are composed of a transport (B) and a separate non-linked enzyme (A) component. Their B-components mediate endocytic uptake into mammalian cells and subsequently transport of the A-components from acidic endosomes into the cytosol, where the latter ADP-ribosylate G-actin resulting in cell rounding and cell death causing clinical symptoms. Protein folding enzymes, including Hsp90 and peptidyl-prolyl cis/trans isomerases facilitate transport of the A-components across endosomal membranes. Here, we identified Hsp70 as a novel host cell factor specifically interacting with A-components of C2, iota and CDT toxins to facilitate their transport into the cell cytosol. Pharmacological Hsp70-inhibition specifically prevented pH-dependent trans-membrane transport of A-components into the cytosol thereby protecting living cells and stem cell-derived human miniguts from intoxication. Thus, Hsp70-inhibition might lead to development of novel therapeutic strategies to treat diseases associated with bacterial ADP-ribosylating toxins.
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Schuster M, Schnell L, Feigl P, Birkhofer C, Mohr K, Roeder M, Carle S, Langer S, Tippel F, Buchner J, Fischer G, Hausch F, Frick M, Schwan C, Aktories K, Schiene-Fischer C, Barth H. The Hsp90 machinery facilitates the transport of diphtheria toxin into human cells. Sci Rep 2017; 7:613. [PMID: 28377614 PMCID: PMC5429619 DOI: 10.1038/s41598-017-00780-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/13/2017] [Indexed: 01/12/2023] Open
Abstract
Diphtheria toxin kills human cells because it delivers its enzyme domain DTA into their cytosol where it inhibits protein synthesis. After receptor-mediated uptake of the toxin, DTA translocates from acidic endosomes into the cytosol, which might be assisted by host cell factors. Here we investigated the role of Hsp90 and its co-chaperones during the uptake of native diphtheria toxin into human cells and identified the components of the Hsp90 machinery including Hsp90, Hsp70, Cyp40 and the FK506 binding proteins FKBP51 and FKBP52 as DTA binding partners. Moreover, pharmacological inhibition of the chaperone activity of Hsp90 and Hsp70 and of the peptidyl-prolyl cis/trans isomerase (PPIase) activity of Cyps and FKBPs protected cells from intoxication with diphtheria toxin and inhibited the pH-dependent trans-membrane transport of DTA into the cytosol. In conclusion, these host cell factors facilitate toxin uptake into human cells, which might lead to development of novel therapeutic strategies against diphtheria.
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Affiliation(s)
- Manuel Schuster
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Leonie Schnell
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Peter Feigl
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Carina Birkhofer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Katharina Mohr
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Maurice Roeder
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Stefan Carle
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Simon Langer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Franziska Tippel
- Munich Center for Integrated Protein Science and Department Chemistry, Technical University of Munich, Munich, Germany
| | - Johannes Buchner
- Munich Center for Integrated Protein Science and Department Chemistry, Technical University of Munich, Munich, Germany
| | - Gunter Fischer
- Max Planck Research Unit for Enzymology of Protein Folding Halle, Halle, Saale, Germany
| | - Felix Hausch
- Institute for Organic Chemistry and Biochemistry, Technical University Darmstadt, Darmstadt, Germany.,Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - Manfred Frick
- Institute of General Physiology, University of Ulm, Ulm, Germany
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104, Freiburg, Germany
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104, Freiburg, Germany
| | - Cordelia Schiene-Fischer
- Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Saale, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany.
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Kronhardt A, Beitzinger C, Barth H, Benz R. Chloroquine Analog Interaction with C2- and Iota-Toxin in Vitro and in Living Cells. Toxins (Basel) 2016; 8:toxins8080237. [PMID: 27517960 PMCID: PMC4999853 DOI: 10.3390/toxins8080237] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/28/2016] [Indexed: 12/22/2022] Open
Abstract
C2-toxin from Clostridium botulinum and Iota-toxin from Clostridium perfringens belong both to the binary A-B-type of toxins consisting of two separately secreted components, an enzymatic subunit A and a binding component B that facilitates the entry of the corresponding enzymatic subunit into the target cells. The enzymatic subunits are in both cases actin ADP-ribosyltransferases that modify R177 of globular actin finally leading to cell death. Following their binding to host cells’ receptors and internalization, the two binding components form heptameric channels in endosomal membranes which mediate the translocation of the enzymatic components Iota a and C2I from endosomes into the cytosol of the target cells. The binding components form ion-permeable channels in artificial and biological membranes. Chloroquine and related 4-aminoquinolines were able to block channel formation in vitro and intoxication of living cells. In this study, we extended our previous work to the use of different chloroquine analogs and demonstrate that positively charged aminoquinolinium salts are able to block channels formed in lipid bilayer membranes by the binding components of C2- and Iota-toxin. Similarly, these molecules protect cultured mammalian cells from intoxication with C2- and Iota-toxin. The aminoquinolinium salts did presumably not interfere with actin ADP-ribosylation or receptor binding but blocked the pores formed by C2IIa and Iota b in living cells and in vitro. The blocking efficiency of pores formed by Iota b and C2IIa by the chloroquine analogs showed interesting differences indicating structural variations between the types of protein-conducting nanochannels formed by Iota b and C2IIa.
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Affiliation(s)
- Angelika Kronhardt
- Rudolf Virchow Center, Research Center for Experimental Biomedicine, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany.
| | - Christoph Beitzinger
- Rudolf Virchow Center, Research Center for Experimental Biomedicine, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs-University Bremen, Campus-Ring 1, 28759 Bremen, Germany.
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Azarnia Tehran D, Pirazzini M, Leka O, Mattarei A, Lista F, Binz T, Rossetto O, Montecucco C. Hsp90 is involved in the entry of clostridial neurotoxins into the cytosol of nerve terminals. Cell Microbiol 2016; 19. [DOI: 10.1111/cmi.12647] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Domenico Azarnia Tehran
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Marco Pirazzini
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Oneda Leka
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Andrea Mattarei
- Department of Chemical Sciences; University of Padova; Via F. Marzolo 1 35131 Padova Italy
| | - Florigio Lista
- Histology and Molecular Biology Section; Army Medical and Veterinary Research Center; Via Santo Stefano Rotondo 4 00184 Rome Italy
| | - Thomas Binz
- Medizinische Hochschule Hannover; Institut für Physiologische Chemie OE4310; 30625 Hannover Germany
| | - Ornella Rossetto
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
- National Research Institute of Neuroscience; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
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EGA Protects Mammalian Cells from Clostridium difficile CDT, Clostridium perfringens Iota Toxin and Clostridium botulinum C2 Toxin. Toxins (Basel) 2016; 8:101. [PMID: 27043629 PMCID: PMC4848627 DOI: 10.3390/toxins8040101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 12/18/2022] Open
Abstract
The pathogenic bacteria Clostridium difficile, Clostridium perfringens and Clostridium botulinum produce the binary actin ADP-ribosylating toxins CDT, iota and C2, respectively. These toxins are composed of a transport component (B) and a separate enzyme component (A). When both components assemble on the surface of mammalian target cells, the B components mediate the entry of the A components via endosomes into the cytosol. Here, the A components ADP-ribosylate G-actin, resulting in depolymerization of F-actin, cell-rounding and eventually death. In the present study, we demonstrate that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone (EGA), a compound that protects cells from multiple toxins and viruses, also protects different mammalian epithelial cells from all three binary actin ADP-ribosylating toxins. In contrast, EGA did not inhibit the intoxication of cells with Clostridium difficile toxins A and B, indicating a possible different entry route for this toxin. EGA does not affect either the binding of the C2 toxin to the cells surface or the enzyme activity of the A components of CDT, iota and C2, suggesting that this compound interferes with cellular uptake of the toxins. Moreover, for C2 toxin, we demonstrated that EGA inhibits the pH-dependent transport of the A component across cell membranes. EGA is not cytotoxic, and therefore, we propose it as a lead compound for the development of novel pharmacological inhibitors against clostridial binary actin ADP-ribosylating toxins.
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A novel Hsp70 inhibitor prevents cell intoxication with the actin ADP-ribosylating Clostridium perfringens iota toxin. Sci Rep 2016; 6:20301. [PMID: 26839186 PMCID: PMC4738285 DOI: 10.1038/srep20301] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/30/2015] [Indexed: 12/14/2022] Open
Abstract
Hsp70 family proteins are folding helper proteins involved in a wide variety of cellular pathways. Members of this family interact with key factors in signal transduction, transcription, cell-cycle control, and stress response. Here, we developed the first Hsp70 low molecular weight inhibitor specifically targeting the peptide binding site of human Hsp70. After demonstrating that the inhibitor modulates the Hsp70 function in the cell, we used the inhibitor to show for the first time that the stress-inducible chaperone Hsp70 functions as molecular component for entry of a bacterial protein toxin into mammalian cells. Pharmacological inhibition of Hsp70 protected cells from intoxication with the binary actin ADP-ribosylating iota toxin from Clostridium perfringens, the prototype of a family of enterotoxins from pathogenic Clostridia and inhibited translocation of its enzyme component across cell membranes into the cytosol. This finding offers a starting point for novel therapeutic strategies against certain bacterial toxins.
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Host Cell Chaperones Hsp70/Hsp90 and Peptidyl-Prolyl Cis/Trans Isomerases Are Required for the Membrane Translocation of Bacterial ADP-Ribosylating Toxins. Curr Top Microbiol Immunol 2016; 406:163-198. [PMID: 27197646 DOI: 10.1007/82_2016_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacterial ADP-ribosylating toxins are the causative agents for several severe human and animal diseases such as diphtheria, cholera, or enteric diseases. They display an AB-type structure: The enzymatically active A-domain attaches to the binding/translocation B-domain which then binds to a receptor on the cell surface. After receptor-mediated endocytosis, the B-domain facilitates the membrane translocation of the unfolded A-domain into the host cell cytosol. Here, the A-domain transfers an ADP-ribose moiety onto its specific substrate which leads to characteristic cellular effects and thus to severe clinical symptoms. Since the A-domain has to reach the cytosol to achieve a cytotoxic effect, the membrane translocation represents a crucial step during toxin uptake. Host cell chaperones including Hsp90 and protein-folding helper enzymes of the peptidyl-prolyl cis/trans isomerase (PPIase) type facilitate this membrane translocation of the unfolded A-domain for ADP-ribosylating toxins but not for toxins with a different enzyme activity. This review summarizes the uptake mechanisms of the ADP-ribosylating clostridial binary toxins, diphtheria toxin (DT) and cholera toxin (CT), with a special focus on the interaction of these toxins with the chaperones Hsp90 and Hsp70 and PPIases of the cyclophilin and FK506-binding protein families during the membrane translocation of their ADP-ribosyltransferase domains into the host cell cytosol. Moreover, the medical implications of host cell chaperones and PPIases as new drug targets for the development of novel therapeutic strategies against diseases caused by bacterial ADP-ribosylating toxins are discussed.
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Ünal CM, Steinert M. Novel therapeutic strategies for Clostridium difficile infections. Expert Opin Ther Targets 2015; 20:269-85. [PMID: 26565670 DOI: 10.1517/14728222.2016.1090428] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION In recent years, Clostridium difficile has become the primary cause of antibiotic-associated diarrhea and pseudomembranous colitis, resulting in long and complicated hospital stays that represent a serious burden for patients as well as health care systems. Currently, conservative treatment of C. difficile infection (CDI) relies on the antibiotics vancomycin, metronidazole or fidaxomicin, or in case of multiple recurrences, fecal microbiota transplantation (FMT). AREAS COVERED The fast-spreading, epidemic nature of this pathogen urgently necessitates the search for alternative treatment strategies as well as antibiotic targets. Accordingly, in this review, we highlight the recent findings regarding virulence associated traits of C. difficile, evaluate their potential as alternative drug targets, and present current efforts in designing inhibitory compounds, with the aim of pointing out possibilities for future treatment strategies. EXPERT OPINION Increased attention on systematic analysis of the virulence mechanisms of C. difficile has already led to the identification of several alternative drug targets. In the future, applying state of the art 'omics' and the development of novel infection models that mimic the human gut, a highly complex ecological niche, will unveil the genomic and metabolic plasticity of this pathogen and will certainly help dealing with future challenges.
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Affiliation(s)
- Can M Ünal
- a 1 Technische Universität Braunschweig, Institut für Mikrobiologie , Spielmannstr. 7, D-38106, Braunschweig, Germany ; .,b 2 Türk-Alman Üniversitesi, Fen Fakültesi , Şahinkaya Cad. 86, 34820, Istanbul, Turkey
| | - Michael Steinert
- a 1 Technische Universität Braunschweig, Institut für Mikrobiologie , Spielmannstr. 7, D-38106, Braunschweig, Germany ; .,c 3 Helmholtz Centre for Infection Research , Mascheroder Weg 1, 38124, Braunschweig, Germany
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Hemmasi S, Czulkies BA, Schorch B, Veit A, Aktories K, Papatheodorou P. Interaction of the Clostridium difficile Binary Toxin CDT and Its Host Cell Receptor, Lipolysis-stimulated Lipoprotein Receptor (LSR). J Biol Chem 2015; 290:14031-44. [PMID: 25882847 DOI: 10.1074/jbc.m115.650523] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Indexed: 12/17/2022] Open
Abstract
CDT (Clostridium difficile transferase) is a binary, actin ADP-ribosylating toxin frequently associated with hypervirulent strains of the human enteric pathogen C. difficile, the most serious cause of antibiotic-associated diarrhea and pseudomembranous colitis. CDT leads to the collapse of the actin cytoskeleton and, eventually, to cell death. Low doses of CDT result in the formation of microtubule-based protrusions on the cell surface that increase the adherence and colonization of C. difficile. The lipolysis-stimulated lipoprotein receptor (LSR) is the host cell receptor for CDT, and our aim was to gain a deeper insight into the interplay between both proteins. We show that CDT interacts with the extracellular, Ig-like domain of LSR with an affinity in the nanomolar range. We identified LSR splice variants in the colon carcinoma cell line HCT116 and disrupted the LSR gene in these cells by applying the CRISPR-Cas9 technology. LSR truncations ectopically expressed in LSR knock-out cells indicated that intracellular parts of LSR are not essential for plasma membrane targeting of the receptor and cellular uptake of CDT. By generating a series of N- and C-terminal truncations of the binding component of CDT (CDTb), we found that amino acids 757-866 of CDTb are sufficient for binding to LSR. With a transposon-based, random mutagenesis approach, we identified potential LSR-interacting epitopes in CDTb. This study increases our understanding about the interaction between CDT and its receptor LSR, which is key to the development of anti-toxin strategies for preventing cell entry of the toxin.
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Affiliation(s)
- Sarah Hemmasi
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Fakultät für Biologie
| | - Bernd A Czulkies
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Hermann Staudinger Graduate School
| | - Björn Schorch
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Fakultät für Biologie, the Spemann Graduate School of Biology and Medicine, and
| | - Antonia Veit
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie
| | - Klaus Aktories
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
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Microbial peptidyl-prolyl cis/trans isomerases (PPIases): virulence factors and potential alternative drug targets. Microbiol Mol Biol Rev 2015; 78:544-71. [PMID: 25184565 DOI: 10.1128/mmbr.00015-14] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Initially discovered in the context of immunomodulation, peptidyl-prolyl cis/trans isomerases (PPIases) were soon identified as enzymes catalyzing the rate-limiting protein folding step at peptidyl bonds preceding proline residues. Intense searches revealed that PPIases are a superfamily of proteins consisting of three structurally distinguishable families with representatives in every described species of prokaryote and eukaryote and, recently, even in some giant viruses. Despite the clear-cut enzymatic activity and ubiquitous distribution of PPIases, reports on solely PPIase-dependent biological roles remain scarce. Nevertheless, they have been found to be involved in a plethora of biological processes, such as gene expression, signal transduction, protein secretion, development, and tissue regeneration, underscoring their general importance. Hence, it is not surprising that PPIases have also been identified as virulence-associated proteins. The extent of contribution to virulence is highly variable and dependent on the pleiotropic roles of a single PPIase in the respective pathogen. The main objective of this review is to discuss this variety in virulence-related bacterial and protozoan PPIases as well as the involvement of host PPIases in infectious processes. Moreover, a special focus is given to Legionella pneumophila macrophage infectivity potentiator (Mip) and Mip-like PPIases of other pathogens, as the best-characterized virulence-related representatives of this family. Finally, the potential of PPIases as alternative drug targets and first tangible results are highlighted.
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Jump RLP, Donskey CJ. Clostridium difficile in the Long-Term Care Facility: Prevention and Management. CURRENT GERIATRICS REPORTS 2015; 4:60-69. [PMID: 25685657 PMCID: PMC4322371 DOI: 10.1007/s13670-014-0108-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Residents of long-term care facilities are at high risk for Clostridium difficile infection due to frequent antibiotic exposure in a population already rendered vulnerable to infection due to advanced age, multiple comorbid conditions and communal living conditions. Moreover, asymptomatic carriage of toxigenic C. difficile and recurrent infections are prevalent in this population. Here, we discuss epidemiology and management of C. difficile infection among residents of long-term care facilities. Also, recognizing that both the population and culture differs significantly from that of hospitals, we also address prevention strategies specific to LTCFs.
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Affiliation(s)
- Robin L. P. Jump
- Geriatric Research Education and Clinical Center, Cleveland
Veterans Affairs Medical Center, Cleveland, Ohio
- Division of Infectious Diseases and HIV Medicine, Department of
Medicine, Case Western, Reserve University, Cleveland, Ohio
| | - Curtis J. Donskey
- Geriatric Research Education and Clinical Center, Cleveland
Veterans Affairs Medical Center, Cleveland, Ohio
- Division of Infectious Diseases and HIV Medicine, Department of
Medicine, Case Western, Reserve University, Cleveland, Ohio
- Research Service, Cleveland Veterans Affairs Medical Center,
Cleveland, Ohio
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Schmidt G, Papatheodorou P, Aktories K. Novel receptors for bacterial protein toxins. Curr Opin Microbiol 2015; 23:55-61. [DOI: 10.1016/j.mib.2014.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 11/05/2014] [Accepted: 11/06/2014] [Indexed: 01/05/2023]
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Ünal CM, Steinert M. FKBPs in bacterial infections. Biochim Biophys Acta Gen Subj 2014; 1850:2096-102. [PMID: 25529296 DOI: 10.1016/j.bbagen.2014.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 12/11/2014] [Accepted: 12/13/2014] [Indexed: 02/05/2023]
Abstract
BACKGROUND FK506-binding proteins (FKBPs) contain a domain with peptidyl-prolyl-cis/trans-isomerase (PPIase) activity and bind the immunosuppressive drugs FK506 and rapamycin. FKBPs belong to the immunophilin family and are found in eukaryotes and bacteria. SCOPE OF REVIEW In this review we describe two major groups of bacterial virulence-associated FKBPs, the trigger factor and Mip-like PPIases. Moreover, we discuss the contribution of host FKBPs in bacterial infection processes. MAJOR CONCLUSIONS Since PPIases are regarded as alternative antiinfective drug targets we highlight current research strategies utilizing pipecolinic acid and cycloheximide derivatives as well as substrate based inhibitors. GENERAL SIGNIFICANCE The current research strategies suggest a beneficial synergism of drug development and basic research. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
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Affiliation(s)
- Can M Ünal
- Türk-Alman Üniversitesi, Fen Fakültesi, Istanbul, Turkey; Technische Universität Braunschweig, Institut für Mikrobiologie, Braunschweig, Germany
| | - Michael Steinert
- Technische Universität Braunschweig, Institut für Mikrobiologie, Braunschweig, Germany; Helmholtz Centre for Infection Research, Braunschweig, Germany.
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