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Sevdalis SE, Varney KM, Cook ME, Gillespie JJ, Pozharski E, Weber DJ. Structural and Functional Insights into the Delivery Systems of Bacillus and Clostridial Binary Toxins. Toxins (Basel) 2024; 16:330. [PMID: 39195740 PMCID: PMC11359772 DOI: 10.3390/toxins16080330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 07/04/2024] [Accepted: 07/19/2024] [Indexed: 08/29/2024] Open
Abstract
Pathogenic Bacillus and clostridial (i.e., Clostridium and Clostridioides) bacteria express a diverse repertoire of effector proteins to promote disease. This includes production of binary toxins, which enter host epithelial cells and seriously damage the intestinal tracts of insects, animals, and humans. In particular, binary toxins form an AB-type complex composed of a catalytic subunit that is toxic (A) and an oligomeric cell-binding and delivery subunit (B), where upon delivery of A into the cytoplasm of the host cell it catalytically ADP-ribosylates actin and rapidly induces host cell death. In this review, binary toxins expressed by Bacillus thuringiensis, Clostridioides difficile, and Clostridium perfringens will be discussed, with particular focus placed upon the structural elucidations of their respective B subunits and how these findings help to deconvolute how toxic enzyme delivery into target host cells is achieved by these deadly bacteria.
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Affiliation(s)
- Spiridon E. Sevdalis
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kristen M. Varney
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Mary E. Cook
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph J. Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Edwin Pozharski
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - David J. Weber
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (K.M.V.); (M.E.C.); (E.P.)
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Tuomisto L, Navarro MA, Mendonça FS, Oliver-Guimerá A, Casanova MI, Keel K, Asin J, Imai D, Stoute S, Mete A, Uzal FA. Clostridium spiroforme-associated enteric disease in domestic rabbits: a retrospective study of 32 cases in California, 1992-2019, and literature review. J Vet Diagn Invest 2024:10406387241257676. [PMID: 38842433 DOI: 10.1177/10406387241257676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024] Open
Abstract
Clostridium spiroforme has been associated with spontaneous and antibiotic-associated enteric disease (C. spiroforme-associated enteric disease, CSAED) in rabbits, which is clinically characterized by anorexia, diarrhea, or sudden death. Diagnosis is usually based on gross and microscopic lesions, coupled with finding the characteristic coiled bacteria in intestinal smears. Isolation of C. spiroforme is often challenging, and a PCR protocol has been developed. We reviewed 32 cases of CSAED submitted for autopsy to the Davis, Tulare, and Turlock laboratories of CAHFS between 1992 and 2019. The reported gross findings were soiling of the perineum, tail, and/or hind legs with diarrhea (16 of 32); gastric (16 of 32), small intestinal (6 of 32), cecal (15 of 32), and/or colonic (4 of 32) distention with brown-to-green, watery content; and serosal hemorrhages in the cecum (15 of 32). The most common microscopic finding was necrotizing enteritis (19 of 32), followed by cecal mucosal or submucosal edema (8 of 32), necrotizing or pleocellular typhlitis (6 of 32), necrotizing or heterophilic typhlocolitis (6 of 32), and cecal transmural hemorrhages (5 of 32). In all 32 rabbits, typical helically coiled, gram-positive bacilli were observed in fecal or intestinal smears. C. spiroforme was isolated from the intestinal content of 2 of 24 rabbits and detected by PCR assay in 8 of 8 rabbits.
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Affiliation(s)
- Laura Tuomisto
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Finland
| | - Mauricio A Navarro
- Instituto de Patología Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Fábio S Mendonça
- Laboratory of Animal Diagnosis, Federal Rural University of Pernambuco, Pernambuco, Brazil
| | - Arturo Oliver-Guimerá
- branches, and Departments of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - M Isabel Casanova
- branches, and Departments of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - Kevin Keel
- branches, and Departments of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - Javier Asin
- California Animal Health and Food Safety Laboratory System-San Bernardino, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - Denise Imai
- branches, and Departments of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - Simone Stoute
- Turlock, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - Aslı Mete
- Davis, School of Veterinary Medicine, University of California-Davis, CA, USA
| | - Francisco A Uzal
- California Animal Health and Food Safety Laboratory System-San Bernardino, School of Veterinary Medicine, University of California-Davis, CA, USA
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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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Abeyawardhane DL, Sevdalis SE, Adipietro KA, Godoy-Ruiz R, Varney KM, Nawaz IF, Spittel AX, Rustandi RR, Silin VI, des Georges A, Pozharski E, Weber DJ. Membrane binding and pore formation is Ca 2+ -dependent for the Clostridioides difficile binary toxin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.18.553786. [PMID: 37645845 PMCID: PMC10462154 DOI: 10.1101/2023.08.18.553786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The C. difficile binary toxin (CDT) enters host cells via endosomal delivery like many other 'AB'-type binary toxins. In this study, the cell-binding component of CDT, termed CDTb, was found to bind and form pores in lipid bilayers upon depleting free Ca 2+ ion concentrations, and not by lowering pH, as found for other binary toxins (i.e., anthrax). Cryoelectron microscopy, nuclear magnetic resonance spectroscopy, surface plasmon resonance, electrochemical impedance spectroscopy, CDT toxicity studies, and site directed mutagenesis show that dissociation of Ca 2+ from a single site in receptor binding domain 1 (RBD1) of CDTb is consistent with a molecular mechanism in which Ca 2+ dissociation from RBD1 induces a "trigger" via conformational exchange that enables CDTb to bind and form pores in endosomal membrane bilayers as free Ca 2+ concentrations decrease during CDT endosomal delivery.
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Hosoya K, Miyashita SI, Karatsu S, Huang IH, Sagane Y. Species-specific gene duplication in Clostridia produces variations of cholesterol-dependent cytolysin with different cytotoxicity. Biochem Biophys Res Commun 2022; 637:240-246. [DOI: 10.1016/j.bbrc.2022.11.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 11/15/2022] [Indexed: 11/17/2022]
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Cryo-EM structures of the translocational binary toxin complex CDTa-bound CDTb-pore from Clostridioides difficile. Nat Commun 2022; 13:6119. [PMID: 36253419 PMCID: PMC9576733 DOI: 10.1038/s41467-022-33888-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/06/2022] [Indexed: 12/24/2022] Open
Abstract
Some bacteria express a binary toxin translocation system, consisting of an enzymatic subunit and translocation pore, that delivers enzymes into host cells through endocytosis. The most clinically important bacterium with such a system is Clostridioides difficile (formerly Clostridium). The CDTa and CDTb proteins from its system represent important therapeutic targets. CDTb has been proposed to be a di-heptamer, but its physiological heptameric structure has not yet been reported. Here, we report the cryo-EM structure of CDTa bound to the CDTb-pore, which reveals that CDTa binding induces partial unfolding and tilting of the first CDTa α-helix. In the CDTb-pore, an NSS-loop exists in 'in' and 'out' conformations, suggesting its involvement in substrate translocation. Finally, 3D variability analysis revealed CDTa movements from a folded to an unfolded state. These dynamic structural information provide insights into drug design against hypervirulent C. difficile strains.
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Pei D, Dalbey RE. Membrane Translocation of Folded Proteins. J Biol Chem 2022; 298:102107. [PMID: 35671825 PMCID: PMC9251779 DOI: 10.1016/j.jbc.2022.102107] [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: 02/05/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022] Open
Abstract
An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part of physiological and/or pathophysiological processes. Herein we provide an overview of the systems/processes that are established or likely to involve the membrane translocation of folded proteins, such as protein export by the twin-arginine translocation (TAT) system in bacteria and chloroplasts, unconventional protein secretion (UPS) and protein import into the peroxisome in eukaryotes, and the cytosolic entry of proteins (e.g., bacterial toxins) and viruses into eukaryotes. We also discuss the various mechanistic models that have previously been proposed for the membrane translocation of folded proteins including pore/channel formation, local membrane disruption, membrane thinning, and transport by membrane vesicles. Finally, we introduce a newly discovered vesicular transport mechanism, vesicle budding and collapse (VBC), and present evidence that VBC may represent a unifying mechanism that drives some (and potentially all) of folded protein translocation processes.
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Affiliation(s)
- Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
| | - Ross E Dalbey
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
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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: 21] [Impact Index Per Article: 10.5] [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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Eisele J, Schreiner S, Borho J, Fischer S, Heber S, Endres S, Fellermann M, Wohlgemuth L, Huber-Lang M, Fois G, Fauler M, Frick M, Barth H. The Pore-Forming Subunit C2IIa of the Binary Clostridium botulinum C2 Toxin Reduces the Chemotactic Translocation of Human Polymorphonuclear Leukocytes. Front Pharmacol 2022; 13:810611. [PMID: 35222028 PMCID: PMC8881014 DOI: 10.3389/fphar.2022.810611] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 01/24/2022] [Indexed: 11/30/2022] Open
Abstract
The binary C2 toxin of Clostridium (C.) botulinum consists of two non-linked proteins, the enzyme subunit C2I and the separate binding/transport subunit C2II. To exhibit toxic effects on mammalian cells, proteolytically activated C2II (C2IIa) forms barrel-shaped heptamers that bind to carbohydrate receptors which are present on all mammalian cell types. C2I binds to C2IIa and the toxin complexes are internalized via receptor-mediated endocytosis. In acidified endosomal vesicles, C2IIa heptamers change their conformation and insert as pores into endosomal membranes. These pores serve as translocation-channels for the subsequent transport of C2I from the endosomal lumen into the cytosol. There, C2I mono-ADP-ribosylates G-actin, which results in depolymerization of F-actin and cell rounding. Noteworthy, so far morphological changes in cells were only observed after incubation with the complete C2 toxin, i.e., C2IIa plus C2I, but not with the single subunits. Unexpectedly, we observed that the non-catalytic transport subunit C2IIa (but not C2II) alone induced morphological changes and actin alterations in primary human polymorphonuclear leukocytes (PMNs, alias neutrophils) from healthy donors ex vivo, but not macrophages, epithelial and endothelial cells, as detected by phase contrast microscopy and fluorescent microscopy of the actin cytoskeleton. This suggests a PMN selective mode of action for C2IIa. The cytotoxicity of C2IIa on PMNs was prevented by C2IIa pore blockers and treatment with C2IIa (but not C2II) rapidly induced Ca2+ influx in PMNs, suggesting that pore-formation by C2IIa in cell membranes of PMNs is crucial for this effect. In addition, incubation of primary human PMNs with C2IIa decreased their chemotaxis ex vivo through porous culture inserts and in co-culture with human endothelial cells which is closer to the physiological extravasation process. In conclusion, the results suggest that C2IIa is a PMN-selective inhibitor of chemotaxis. This provides new knowledge for a pathophysiological role of C2 toxin as a modulator of innate immune cells and makes C2IIa an attractive candidate for the development of novel pharmacological strategies to selectively down-modulate the excessive and detrimental PMN recruitment into organs after traumatic injuries.
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Affiliation(s)
- Julia Eisele
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Simone Schreiner
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Joscha Borho
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Stephan Fischer
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Sebastian Heber
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Sascha Endres
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Maximilian Fellermann
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Lisa Wohlgemuth
- Institute of Clinical and Experimental Trauma Immunology, Ulm University Medical Center, Ulm, Germany
| | - Markus Huber-Lang
- Institute of Clinical and Experimental Trauma Immunology, Ulm University Medical Center, Ulm, Germany
| | - Giorgio Fois
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Michael Fauler
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
- *Correspondence: Holger Barth,
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Benz R, Piselli C, Hoxha C, Koy C, Glocker MO, Popoff MR. Clostridium perfringens Beta2 toxin forms highly cation-selective channels in lipid bilayers. EUROPEAN BIOPHYSICS JOURNAL 2022; 51:15-27. [PMID: 34854958 PMCID: PMC8827211 DOI: 10.1007/s00249-021-01577-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/28/2021] [Accepted: 11/14/2021] [Indexed: 11/27/2022]
Abstract
Clostridium perfringens is a potent producer of a variety of toxins. Well studied from these are five toxins (alpha, Beta (CPB), epsilon, iota and CPE) that are produced by seven toxinotype strains (A–G) of C. perfringens. Besides these toxins, C. perfringens produces also another toxin that causes necrotizing enterocolitis in piglets. This toxin termed consensus Beta2 toxin (cCPB2) has a molecular mass of 27,620 Da and shows only little homology to CPB and no one to the other toxins of C. perfringens. Its primary action on cells remained unknown to date. cCPB2 was heterogeneously expressed as fusion protein with GST in Escherichia coli and purified to homogeneity. Although cCPB2 does not exhibit the typical structure of beta-stranded pore-forming proteins and contains no indication for the presence of amphipathic alpha-helices we could demonstrate that cCPB2 is a pore-forming component with an extremely high activity in lipid bilayers. The channels have a single-channel conductance of about 700 pS in 1 M KCl and are highly cation-selective as judged from selectivity measurements in the presence of salt gradients. The high cation selectivity is caused by the presence of net negative charges in or near the channel that allowed an estimate of the channel size being about 1.4 nm wide. Our measurements suggest that the primary effect of cCPB2 is the formation of cation-selective channels followed by necrotic enteritis in humans and animals. We searched in databases for homologs of cCPB2 and constructed a cladogram representing the phylogenetic relationship to the next relatives of cCPB2.
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Affiliation(s)
- Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759, Bremen, Germany.
| | - Claudio Piselli
- Department of Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759, Bremen, Germany
| | - Cezarela Hoxha
- Department of Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759, Bremen, Germany
- Bacterial Toxins, Institut Pasteur, 28 Rue du Dr Roux, Paris, France
| | - Cornelia Koy
- Proteome Center Rostock, University Medicine Rostock, 18059, Rostock, Germany
| | - Michael O Glocker
- Proteome Center Rostock, University Medicine Rostock, 18059, Rostock, Germany
| | - Michel R Popoff
- Bacterial Toxins, Institut Pasteur, 28 Rue du Dr Roux, Paris, France
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Kouadio JL, Zheng M, Aikins M, Duda D, Duff S, Chen D, Zhang J, Milligan J, Taylor C, Mamanella P, Rydel T, Kessenich C, Panosian T, Yin Y, Moar W, Giddings K, Park Y, Jerga A, Haas J. Structural and functional insights into the first Bacillus thuringiensis vegetative insecticidal protein of the Vpb4 fold, active against western corn rootworm. PLoS One 2021; 16:e0260532. [PMID: 34928980 PMCID: PMC8687597 DOI: 10.1371/journal.pone.0260532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 11/11/2021] [Indexed: 01/09/2023] Open
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a major maize pest in the United States causing significant economic loss. The emergence of field-evolved resistant WCR to Bacillus thuringiensis (Bt) traits has prompted the need to discover and deploy new insecticidal proteins in transgenic maize. In the current study we determined the crystal structure and mode of action (MOA) of the Vpb4Da2 protein (formerly known as Vip4Da2) from Bt, the first identified insecticidal Vpb4 protein with commercial level control against WCR. The Vpb4Da2 structure exhibits a six-domain architecture mainly comprised of antiparallel β-sheets organized into β-sandwich layers. The amino-terminal domains 1-3 of the protein share structural homology with the protective antigen (PA) PA14 domain and encompass a long β-pore forming loop as in the clostridial binary-toxB module. Domains 5 and 6 at the carboxyl-terminal half of Vpb4Da2 are unique as this extension is not observed in PA or any other structurally-related protein other than Vpb4 homologs. These unique Vpb4 domains adopt the topologies of carbohydrate-binding modules known to participate in receptor-recognition. Functional assessment of Vpb4Da2 suggests that domains 4-6 comprise the WCR receptor binding region and are key in conferring the observed insecticidal activity against WCR. The current structural analysis was complemented by in vitro and in vivo characterizations, including immuno-histochemistry, demonstrating that Vpb4Da2 follows a MOA that is consistent with well-characterized 3-domain Bt insecticidal proteins despite significant structural differences.
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Affiliation(s)
| | - Meiying Zheng
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Michael Aikins
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America
| | - David Duda
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Stephen Duff
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Danqi Chen
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jun Zhang
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jason Milligan
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Christina Taylor
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | | | - Timothy Rydel
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Colton Kessenich
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Timothy Panosian
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Yong Yin
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - William Moar
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Kara Giddings
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Yoonseong Park
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America
| | - Agoston Jerga
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jeffrey Haas
- Bayer Crop Science, Chesterfield, Missouri, United States of America
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12
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Nagahama M, Kobayashi K, Takehara M. Cathepsin Release from Lysosomes Promotes Endocytosis of Clostridium perfringens Iota-Toxin. Toxins (Basel) 2021; 13:toxins13100721. [PMID: 34679014 PMCID: PMC8537257 DOI: 10.3390/toxins13100721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/06/2021] [Accepted: 10/11/2021] [Indexed: 11/25/2022] Open
Abstract
Iota-toxin from Clostridium perfringens type E is a binary toxin composed of two independent proteins: actin-ADP-ribosylating enzyme component, iota-a (Ia), and binding component, iota-b (Ib). Ib binds to target cell receptors and mediates the internalization of Ia into the cytoplasm. Extracellular lysosomal enzyme acid sphingomyelinase (ASMase) was previously shown to facilitate the internalization of iota-toxin. In this study, we investigated how lysosomal cathepsin promotes the internalization of iota-toxin into target cells. Cysteine protease inhibitor E64 prevented the cytotoxicity caused by iota-toxin, but aspartate protease inhibitor pepstatin-A and serine protease inhibitor AEBSF did not. Knockdown of lysosomal cysteine protease cathepsins B and L decreased the toxin-induced cytotoxicity. E64 suppressed the Ib-induced ASMase activity in extracellular fluid, showing that the proteases play a role in ASMase activation. These results indicate that cathepsin B and L facilitate entry of iota-toxin via activation of ASMase.
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13
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High Serum Levels of Toxin A Correlate with Disease Severity in Patients with Clostridioides difficile Infection. Antibiotics (Basel) 2021; 10:antibiotics10091093. [PMID: 34572675 PMCID: PMC8470527 DOI: 10.3390/antibiotics10091093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/30/2021] [Accepted: 09/07/2021] [Indexed: 12/13/2022] Open
Abstract
Cloistridioides difficile (CD) represents a major public healthcare-associated infection causing significant morbidity and mortality. The pathogenic effects of CD are mainly caused by the release of two exotoxins into the intestine: toxin A (TcdA) and toxin B (TcdB). CD infection (CDI) can also cause toxemia, explaining the systemic complications of life-threatening cases. Currently, there is a lack of sensitive assays to detect exotoxins circulating in the blood. Here, we report a new semi-quantitative diagnostic method to measure CD toxins serum levels. The dot-blot assay was modified to separately detect TcdA and TcdB in human serum with a limit of detection at the pg/mL levels. TcdA and TcdB concentrations in the plasma of 35 CDI patients were measured at the time of CDI diagnosis and at the fourth and tenth day after CDI diagnosis and initiation of anti-CDI treatment. TcdA and TcdB levels were compared to those determined in nine healthy blood donors. Toxemia was detected in the plasma of 33 out of the 35 CDI cases. We also assessed the relationship between TcdA serum levels and CDI severity, reporting that at the time of CDI diagnosis the proportion of severe CDI cases with a TcdA serum level > 60 pg/µL was higher than in mild CDI cases (29.4% versus 66.6%, p = 0.04). In conclusion, data reported here demonstrate for the first time that toxemia is much more frequent than expected in CDI patients, and specifically that high serum levels of TcdA correlate with disease severity in patients with CDI.
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14
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Liu W, Nestorovich EM. Anthrax toxin channel: What we know based on over 30 years of research. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183715. [PMID: 34332985 DOI: 10.1016/j.bbamem.2021.183715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Protective antigen channel is the central component of the deadly anthrax exotoxin responsible for binding and delivery of the toxin's enzymatic lethal and edema factor components into the cytosol. The channel, which is more than three times longer than the lipid bilayer membrane thickness and has a 6-Å limiting diameter, is believed to provide a sophisticated unfoldase and translocase machinery for the foreign protein transport into the host cell cytosol. The tripartite toxin can be reengineered, one component at a time or collectively, to adapt it for the targeted cancer therapeutic treatments. In this review, we focus on the biophysical studies of the protective antigen channel-forming activity, small ion transport properties, enzymatic factor translocation, and blockage comparing it with the related clostridial binary toxin channels. We address issues linked to the anthrax toxin channel structural dynamics and lipid dependence, which are yet to become generally recognized as parts of the toxin translocation machinery.
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Affiliation(s)
- Wenxing Liu
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA.
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15
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Internalization of Clostridium botulinum C2 Toxin Is Regulated by Cathepsin B Released from Lysosomes. Toxins (Basel) 2021; 13:toxins13040272. [PMID: 33918753 PMCID: PMC8069846 DOI: 10.3390/toxins13040272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 04/03/2021] [Accepted: 04/07/2021] [Indexed: 11/16/2022] Open
Abstract
Clostridium botulinum C2 toxin is a clostridial binary toxin consisting of actin ADP-ribosyltransferase (C2I) and C2II binding components. Activated C2II (C2IIa) binds to cellular receptors and forms oligomer in membrane rafts. C2IIa oligomer assembles with C2I and contributes to the transport of C2I into the cytoplasm of host cells. C2IIa induces Ca2+-induced lysosomal exocytosis, extracellular release of the acid sphingomyelinase (ASMase), and membrane invagination and endocytosis through generating ceramides in the membrane by ASMase. Here, we reveal that C2 toxin requires the lysosomal enzyme cathepsin B (CTSB) during endocytosis. Lysosomes are a rich source of proteases, containing cysteine protease CTSB and cathepsin L (CTSL), and aspartyl protease cathepsin D (CTSD). Cysteine protease inhibitor E64 blocked C2 toxin-induced cell rounding, but aspartyl protease inhibitor pepstatin-A did not. E64 inhibited the C2IIa-promoted extracellular ASMase activity, indicating that the protease contributes to the activation of ASMase. C2IIa induced the extracellular release of CTSB and CTSL, but not CTSD. CTSB knockdown by siRNA suppressed C2 toxin-caused cytotoxicity, but not siCTSL. These findings demonstrate that CTSB is important for effective cellular entry of C2 toxin into cells through increasing ASMase activity.
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16
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Cook ME, Varney KM, Godoy-Ruiz R, Weber DJ. 1H N, 13C, and 15N resonance assignments of the Clostridioides difficile receptor binding domain 2 (CDTb, residues 757-876). BIOMOLECULAR NMR ASSIGNMENTS 2021; 15:35-39. [PMID: 33034833 PMCID: PMC7973916 DOI: 10.1007/s12104-020-09979-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
Clostridioides difficile is a bacterial pathogen responsible for the majority of nosocomial infections in the developed world. C. difficile infection (CDI) is difficult to treat in many cases because hypervirulent strains have evolved that contain a third toxin, termed the C. difficile toxin (CDT), in addition to the two enterotoxins TcdA and TcdB. CDT is a binary toxin comprised of an enzymatic, ADP-ribosyltransferase (ART) toxin component, CDTa, and a pore-forming or delivery subunit, CDTb. In the absence of CDTa, CDTb assembles into two distinct di-heptameric states, a symmetric and an asymmetric form with both states having two surface-accessible host cell receptor-binding domains, termed RBD1 and RBD2. RBD1 has a unique amino acid sequence, when aligned to other well-studied binary toxins (i.e., anthrax), and it contains a novel Ca2+-binding site important for CDTb stability. The other receptor binding domain, RBD2, is critically important for CDT toxicity, and a domain such as this is missing altogether in other binary toxins and shows further that CDT is unique when compared to other binary toxins. In this study, the 1H, 13C, and 15N backbone and sidechain resonances of the 120 amino acid RBD2 domain of CDTb (residues 757-876) were assigned sequence-specifically and provide a framework for future NMR-based drug discovery studies directed towards targeting the most virulent strains of CDI.
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Affiliation(s)
- Mary E Cook
- Department of Biochemistry and Molecular Biology, Center for Biomolecular Therapeutics (CBT), University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD, 21201, USA
| | - Kristen M Varney
- Department of Biochemistry and Molecular Biology, Center for Biomolecular Therapeutics (CBT), University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD, 21201, USA
| | - Raquel Godoy-Ruiz
- Department of Biochemistry and Molecular Biology, Center for Biomolecular Therapeutics (CBT), University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD, 21201, USA
| | - David J Weber
- Department of Biochemistry and Molecular Biology, Center for Biomolecular Therapeutics (CBT), University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD, 21201, USA.
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17
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Abeyawardhane DL, Godoy-Ruiz R, Adipietro KA, Varney KM, Rustandi RR, Pozharski E, Weber DJ. The Importance of Therapeutically Targeting the Binary Toxin from Clostridioides difficile. Int J Mol Sci 2021; 22:2926. [PMID: 33805767 PMCID: PMC8001090 DOI: 10.3390/ijms22062926] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 02/06/2023] Open
Abstract
Novel therapeutics are needed to treat pathologies associated with the Clostridioides difficile binary toxin (CDT), particularly when C. difficile infection (CDI) occurs in the elderly or in hospitalized patients having illnesses, in addition to CDI, such as cancer. While therapies are available to block toxicities associated with the large clostridial toxins (TcdA and TcdB) in this nosocomial disease, nothing is available yet to treat toxicities arising from strains of CDI having the binary toxin. Like other binary toxins, the active CDTa catalytic subunit of CDT is delivered into host cells together with an oligomeric assembly of CDTb subunits via host cell receptor-mediated endocytosis. Once CDT arrives in the host cell's cytoplasm, CDTa catalyzes the ADP-ribosylation of G-actin leading to degradation of the cytoskeleton and rapid cell death. Although a detailed molecular mechanism for CDT entry and host cell toxicity is not yet fully established, structural and functional resemblances to other binary toxins are described. Additionally, unique conformational assemblies of individual CDT components are highlighted herein to refine our mechanistic understanding of this deadly toxin as is needed to develop effective new therapeutic strategies for treating some of the most hypervirulent and lethal strains of CDT-containing strains of CDI.
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Affiliation(s)
- Dinendra L. Abeyawardhane
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (D.L.A.); (R.G.-R.); (K.A.A.); (K.M.V.); (E.P.)
- Baltimore—Institute for Bioscience and Biotechnology Research, University of Maryland-Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Raquel Godoy-Ruiz
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (D.L.A.); (R.G.-R.); (K.A.A.); (K.M.V.); (E.P.)
- Baltimore—Institute for Bioscience and Biotechnology Research, University of Maryland-Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kaylin A. Adipietro
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (D.L.A.); (R.G.-R.); (K.A.A.); (K.M.V.); (E.P.)
- The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kristen M. Varney
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (D.L.A.); (R.G.-R.); (K.A.A.); (K.M.V.); (E.P.)
- Baltimore—Institute for Bioscience and Biotechnology Research, University of Maryland-Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | - Edwin Pozharski
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (D.L.A.); (R.G.-R.); (K.A.A.); (K.M.V.); (E.P.)
- Baltimore—Institute for Bioscience and Biotechnology Research, University of Maryland-Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - David J. Weber
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (D.L.A.); (R.G.-R.); (K.A.A.); (K.M.V.); (E.P.)
- Baltimore—Institute for Bioscience and Biotechnology Research, University of Maryland-Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
- The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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18
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Current Insights on Vegetative Insecticidal Proteins (Vip) as Next Generation Pest Killers. Toxins (Basel) 2020; 12:toxins12080522. [PMID: 32823872 PMCID: PMC7472478 DOI: 10.3390/toxins12080522] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/09/2020] [Accepted: 08/11/2020] [Indexed: 02/01/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram negative soil bacterium. This bacterium secretes various proteins during different growth phases with an insecticidal potential against many economically important crop pests. One of the important families of Bt proteins is vegetative insecticidal proteins (Vip), which are secreted into the growth medium during vegetative growth. There are three subfamilies of Vip proteins. Vip1 and Vip2 heterodimer toxins have an insecticidal activity against many Coleopteran and Hemipteran pests. Vip3, the most extensively studied family of Vip toxins, is effective against Lepidopteron. Vip proteins do not share homology in sequence and binding sites with Cry proteins, but share similarities at some points in their mechanism of action. Vip3 proteins are expressed as pyramids alongside Cry proteins in crops like maize and cotton, so as to control resistant pests and delay the evolution of resistance. Biotechnological- and in silico-based analyses are promising for the generation of mutant Vip proteins with an enhanced insecticidal activity and broader spectrum of target insects.
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19
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Xu X, Godoy-Ruiz R, Adipietro KA, Peralta C, Ben-Hail D, Varney KM, Cook ME, Roth BM, Wilder PT, Cleveland T, Grishaev A, Neu HM, Michel SLJ, Yu W, Beckett D, Rustandi RR, Lancaster C, Loughney JW, Kristopeit A, Christanti S, Olson JW, MacKerell AD, Georges AD, Pozharski E, Weber DJ. Structure of the cell-binding component of the Clostridium difficile binary toxin reveals a di-heptamer macromolecular assembly. Proc Natl Acad Sci U S A 2020; 117:1049-1058. [PMID: 31896582 PMCID: PMC6969506 DOI: 10.1073/pnas.1919490117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Targeting Clostridium difficile infection is challenging because treatment options are limited, and high recurrence rates are common. One reason for this is that hypervirulent C. difficile strains often have a binary toxin termed the C. difficile toxin, in addition to the enterotoxins TsdA and TsdB. The C. difficile toxin has an enzymatic component, termed CDTa, and a pore-forming or delivery subunit termed CDTb. CDTb was characterized here using a combination of single-particle cryoelectron microscopy, X-ray crystallography, NMR, and other biophysical methods. In the absence of CDTa, 2 di-heptamer structures for activated CDTb (1.0 MDa) were solved at atomic resolution, including a symmetric (SymCDTb; 3.14 Å) and an asymmetric form (AsymCDTb; 2.84 Å). Roles played by 2 receptor-binding domains of activated CDTb were of particular interest since the receptor-binding domain 1 lacks sequence homology to any other known toxin, and the receptor-binding domain 2 is completely absent in other well-studied heptameric toxins (i.e., anthrax). For AsymCDTb, a Ca2+ binding site was discovered in the first receptor-binding domain that is important for its stability, and the second receptor-binding domain was found to be critical for host cell toxicity and the di-heptamer fold for both forms of activated CDTb. Together, these studies represent a starting point for developing structure-based drug-design strategies to target the most severe strains of C. difficile.
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Affiliation(s)
- Xingjian Xu
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017
- PhD Program in Biochemistry, The Graduate Center, City University of New York, New York, NY 10017
| | - Raquel Godoy-Ruiz
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Kaylin A Adipietro
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Christopher Peralta
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017
| | - Danya Ben-Hail
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017
| | - Kristen M Varney
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Mary E Cook
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Braden M Roth
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Paul T Wilder
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | | | | | - Heather M Neu
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Sarah L J Michel
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Wenbo Yu
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Dorothy Beckett
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742
| | | | | | | | | | | | | | - Alexander D MacKerell
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Amedee des Georges
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017;
- PhD Program in Biochemistry, The Graduate Center, City University of New York, New York, NY 10017
- PhD Program in Chemistry, The Graduate Center, City University of New York, New York, NY 10017
- Department of Chemistry & Biochemistry, City College of New York, New York, NY 10031
| | - Edwin Pozharski
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201;
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - David J Weber
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201;
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
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20
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Exploring the Nature of Cationic Blocker Recognition by the Anthrax Toxin Channel. Biophys J 2019; 117:1751-1763. [PMID: 31587826 DOI: 10.1016/j.bpj.2019.08.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/11/2019] [Accepted: 08/05/2019] [Indexed: 01/20/2023] Open
Abstract
Obstructing conductive pathways of the channel-forming toxins with targeted blockers is a promising drug design approach. Nearly all tested positively charged ligands have been shown to reversibly block the cation-selective channel-forming protective antigen (PA63) component of the binary anthrax toxin. The cationic ligands with more hydrophobic surfaces, particularly those carrying aromatic moieties, inhibited PA63 more effectively. To understand the physical basis of PA63 selectivity for a particular ligand, detailed information is required on how the blocker structural elements (e.g., positively charged and aromatic groups) influence the molecular kinetics of the blocker/channel binding reactions. In this study, we address this problem using the high-resolution single-channel planar lipid bilayer technique. Several structurally distinct cationic blockers, namely per-6-S-(3-amino) propyl-β-cyclodextrin, per-6-S-(3-aminomethyl) benzyl-α-cyclodextrin, per-6-S-(3-aminomethyl) benzyl-β-cyclodextrin, per-6-S-(3-aminomethyl) benzyl-γ-cyclodextrin, methyltriphenylphosphonium ion, and G0 polyamidoamine dendrimer are tested for their ability to inhibit the heptameric and octameric PA63 variants and PA63F427A mutant. The F427 residues form a hydrophobic constriction region inside the channel, known as the "ϕ-clamp." We show that the cationic blockers interact with PA63 through a combination of forces. Analysis of the binding reaction kinetics suggests the involvement of cation-π, Coulomb, and salt-concentration-independent π-π or hydrophobic interactions in the cationic cyclodextrin binding. It is possible that these blockers bind to the ϕ-clamp and are also stabilized by the Coulomb interactions of their terminal amino groups with the water-exposed negatively charged channel residues. In PA63F427A, only the suggested Coulomb component of the cyclodextrin interaction remains. Methyltriphenylphosphonium ion and G0 polyamidoamine dendrimer, despite being positively charged, interact primarily with the ϕ-clamp. We also show that seven- and eightfold symmetric cyclodextrins effectively block the heptameric and octameric forms of PA63 interchangeably, adding flexibility to the earlier formulated blocker/target symmetry match requirement.
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21
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Yamini G, Nestorovich EM. Multivalent Inhibitors of Channel-Forming Bacterial Toxins. Curr Top Microbiol Immunol 2019; 406:199-227. [PMID: 27469304 PMCID: PMC6814628 DOI: 10.1007/82_2016_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Rational design of multivalent molecules represents a remarkable modern tool to transform weak non-covalent interactions into strong binding by creating multiple finely-tuned points of contact between multivalent ligands and their supposed multivalent targets. Here, we describe several prominent examples where the multivalent blockers were investigated for their ability to directly obstruct oligomeric channel-forming bacterial exotoxins, such as the pore-forming bacterial toxins and B component of the binary bacterial toxins. We address problems related to the blocker/target symmetry match and nature of the functional groups, as well as chemistry and length of the linkers connecting the functional groups to their multivalent scaffolds. Using the anthrax toxin and AB5 toxin case studies, we briefly review how the oligomeric toxin components can be successfully disabled by the multivalent non-channel-blocking inhibitors, which are based on a variety of multivalent scaffolds.
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Affiliation(s)
- Goli Yamini
- Department of Biology, The Catholic University of America, Washington, D.C., 20064, USA
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22
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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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23
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Revitt-Mills SA, Vidor CJ, Watts TD, Lyras D, Rood JI, Adams V. Virulence Plasmids of the Pathogenic Clostridia. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0034-2018. [PMID: 31111816 PMCID: PMC11257192 DOI: 10.1128/microbiolspec.gpp3-0034-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Indexed: 12/12/2022] Open
Abstract
The clostridia cause a spectrum of diseases in humans and animals ranging from life-threatening tetanus and botulism, uterine infections, histotoxic infections and enteric diseases, including antibiotic-associated diarrhea, and food poisoning. The symptoms of all these diseases are the result of potent protein toxins produced by these organisms. These toxins are diverse, ranging from a multitude of pore-forming toxins to phospholipases, metalloproteases, ADP-ribosyltransferases and large glycosyltransferases. The location of the toxin genes is the unifying theme of this review because with one or two exceptions they are all located on plasmids or on bacteriophage that replicate using a plasmid-like intermediate. Some of these plasmids are distantly related whilst others share little or no similarity. Many of these toxin plasmids have been shown to be conjugative. The mobile nature of these toxin genes gives a ready explanation of how clostridial toxin genes have been so widely disseminated both within the clostridial genera as well as in the wider bacterial community.
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Affiliation(s)
- Sarah A Revitt-Mills
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Callum J Vidor
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Thomas D Watts
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Dena Lyras
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Julian I Rood
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Vicki Adams
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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Schnell L, Felix I, Müller B, Sadi M, Bank F, Papatheodorou P, Popoff MR, Aktories K, Waltenberger E, Benz R, Weichbrodt C, Fauler M, Frick M, Barth H. Revisiting an old antibiotic: bacitracin neutralizes binary bacterial toxins and protects cells from intoxication. FASEB J 2019; 33:5755-5771. [DOI: 10.1096/fj.201802453r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Leonie Schnell
- Institute of Pharmacology and ToxicologyUniversity of Ulm Medical Center Ulm Germany
| | - Ina Felix
- Institute of Pharmacology and ToxicologyUniversity of Ulm Medical Center Ulm Germany
| | - Bastian Müller
- Institute of Pharmacology and ToxicologyUniversity of Ulm Medical Center Ulm Germany
| | - Mirko Sadi
- Institute of Pharmacology and ToxicologyUniversity of Ulm Medical Center Ulm Germany
| | - Franziska Bank
- Institute of Pharmacology and ToxicologyUniversity of Ulm Medical Center Ulm Germany
| | | | | | - Klaus Aktories
- Institute of ExperimentalClinical Pharmacology and ToxicologyUniversity of Freiburg Freiburg Germany
| | - Eva Waltenberger
- Department of Life Sciences and ChemistryJacobs University Bremen Bremen Germany
| | - Roland Benz
- Department of Life Sciences and ChemistryJacobs University Bremen Bremen Germany
| | | | - Michael Fauler
- Institute of General PhysiologyUniversity of Ulm Ulm Germany
| | - Manfred Frick
- Institute of General PhysiologyUniversity of Ulm Ulm Germany
| | - Holger Barth
- Institute of Pharmacology and ToxicologyUniversity of Ulm Medical Center Ulm Germany
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25
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Nagahama M, Takehara M, Kobayashi K. Interaction of Clostridium perfringens Iota Toxin and Lipolysis-Stimulated Lipoprotein Receptor (LSR). Toxins (Basel) 2018; 10:toxins10100405. [PMID: 30297616 PMCID: PMC6215307 DOI: 10.3390/toxins10100405] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 09/29/2018] [Accepted: 10/04/2018] [Indexed: 01/05/2023] Open
Abstract
Iota toxin produced by Clostridium perfringens is a binary, actin ADP-ribosylating toxin that is organized into the enzymatically active component Ia and the binding component Ib. Lipolysis-stimulated lipoprotein receptor (LSR) has been identified as a cellular receptor of Ib. Here, we investigated the functional interaction between Ib and LSR, where siRNA for LSR blocked the toxin-mediated cytotoxicity and the binding of Ib. The addition of Ib to LSR-green fluorescence protein (GFP)-transfected cells at 4 °C resulted in colocalization with LSR and Ib on the cell surface. Upon transfer of the cells from 4 °C to 37 °C, LSR and Ib were internalized and observed in cytoplasmic vesicles. When the cells were incubated with Ib at 37 °C and fractionated using the Triton-insoluble membrane, Ib oligomer was localized in insoluble factions that fulfilled the criteria of lipid rafts, and LSR was clustered in lipid rafts. To examine the interaction between N-terminal extracellular region of LSR and Ib, we constructed a series of LSR N-terminal deletions. Ten amino acids residues can be deleted from this end without any reduction of Ib binding. However, deletion of 15 N-terminal residues drastically reduces its ability to bind Ib. These results demonstrate that Ib binds to the LSR N-terminal 10 to 15 residues and endocytoses into trafficking endosomes together with LSR.
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Affiliation(s)
- Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Masaya Takehara
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Keiko Kobayashi
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
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26
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Benz R, Popoff MR. Clostridium perfringens Enterotoxin: The Toxin Forms Highly Cation-Selective Channels in Lipid Bilayers. Toxins (Basel) 2018; 10:toxins10090341. [PMID: 30135397 PMCID: PMC6162509 DOI: 10.3390/toxins10090341] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/14/2018] [Accepted: 08/14/2018] [Indexed: 02/07/2023] Open
Abstract
One of the numerous toxins produced by Clostridium perfringens is Clostridium perfringens enterotoxin (CPE), a polypeptide with a molecular mass of 35.5 kDa exhibiting three different domains. Domain one is responsible for receptor binding, domain two is involved in hexamer formation and domain three has to do with channel formation in membranes. CPE is the major virulence factor of this bacterium and acts on the claudin-receptor containing tight junctions between epithelial cells resulting in various gastrointestinal diseases. The activity of CPE on Vero cells was demonstrated by the entry of propidium iodide (PI) in the cells. The entry of propidium iodide caused by CPE was well correlated with the loss of cell viability monitored by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. CPE formed ion-permeable channels in artificial lipid bilayer membranes with a single-channel conductance of 620 pS in 1 M KCl. The single-channel conductance was not a linear function of the bulk aqueous salt concentration indicating that point-negative charges at the CPE channel controlled ion transport. This resulted in the high cation selectivity of the CPE channels, which suggested that anions are presumably not permeable through the CPE channels. The possible role of cation transport by CPE channels in disease caused by C. perfringens is discussed.
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Affiliation(s)
- Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University, Campusring 1, 28759 Bremen, Germany.
| | - Michel R Popoff
- Bacterial Toxins, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France.
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27
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Mechanisms of Action and Cell Death Associated with Clostridium perfringens Toxins. Toxins (Basel) 2018; 10:toxins10050212. [PMID: 29786671 PMCID: PMC5983268 DOI: 10.3390/toxins10050212] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/18/2018] [Accepted: 05/19/2018] [Indexed: 12/26/2022] Open
Abstract
Clostridium perfringens uses its large arsenal of protein toxins to produce histotoxic, neurologic and intestinal infections in humans and animals. The major toxins involved in diseases are alpha (CPA), beta (CPB), epsilon (ETX), iota (ITX), enterotoxin (CPE), and necrotic B-like (NetB) toxins. CPA is the main virulence factor involved in gas gangrene in humans, whereas its role in animal diseases is limited and controversial. CPB is responsible for necrotizing enteritis and enterotoxemia, mostly in neonatal individuals of many animal species, including humans. ETX is the main toxin involved in enterotoxemia of sheep and goats. ITX has been implicated in cases of enteritis in rabbits and other animal species; however, its specific role in causing disease has not been proved. CPE is responsible for human food-poisoning and non-foodborne C. perfringens-mediated diarrhea. NetB is the cause of necrotic enteritis in chickens. In most cases, host–toxin interaction starts on the plasma membrane of target cells via specific receptors, resulting in the activation of intracellular pathways with a variety of effects, commonly including cell death. In general, the molecular mechanisms of cell death associated with C. perfringens toxins involve features of apoptosis, necrosis and/or necroptosis.
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Nagahama M, Takehara M, Miyamoto K, Ishidoh K, Kobayashi K. Acid Sphingomyelinase Promotes Cellular Internalization of Clostridium perfringens Iota-Toxin. Toxins (Basel) 2018; 10:toxins10050209. [PMID: 29783772 PMCID: PMC5983265 DOI: 10.3390/toxins10050209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 11/16/2022] Open
Abstract
Clostridium perfringens iota-toxin is a binary actin-ADP-ribosylating toxin composed of the enzymatic component Ia and receptor binding component Ib. Ib binds to a cell surface receptor, forms Ib oligomer in lipid rafts, and associates with Ia. The Ia-Ib complex then internalizes by endocytosis. Here, we showed that acid sphingomyelinase (ASMase) facilitates the cellular uptake of iota-toxin. Inhibitions of ASMase and lysosomal exocytosis by respective blockers depressed cell rounding induced by iota-toxin. The cytotoxicity of the toxin increased in the presence of Ca2+ in extracellular fluids. Ib entered target cells in the presence but not the absence of Ca2+. Ib induced the extracellular release of ASMase in the presence of Ca2+. ASMase siRNA prevented the cell rounding induced by iota-toxin. Furthermore, treatment of the cells with Ib resulted in the production of ceramide in cytoplasmic vesicles. These observations showed that ASMase promotes the internalization of iota-toxin into target cells.
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Affiliation(s)
- Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Masaya Takehara
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Kazuaki Miyamoto
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Kazumi Ishidoh
- Division of Molecular Biology, Institute for Health Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
| | - Keiko Kobayashi
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
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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: 210] [Impact Index Per Article: 30.0] [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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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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Cellular Uptake of Clostridium botulinum C2 Toxin Requires Acid Sphingomyelinase Activity. Infect Immun 2017; 85:IAI.00966-16. [PMID: 28138018 DOI: 10.1128/iai.00966-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 11/22/2016] [Indexed: 01/06/2023] Open
Abstract
Clostridium botulinum C2 toxin consists of an enzyme component (C2I) and a binding component (C2II). Activated C2II (C2IIa) binds to a cell receptor, giving rise to lipid raft-dependent oligomerization, and it then assembles with C2I. The whole toxin complex is then endocytosed into the cytosol, resulting in the destruction of the actin cytoskeleton and cell rounding. Here, we showed that C2 toxin requires acid sphingomyelinase (ASMase) activity during internalization. In this study, inhibitors of ASMase and lysosomal exocytosis blocked C2 toxin-induced cell rounding. C2IIa induced Ca2+ influx from the extracellular medium to cells. C2 toxin-induced cell rounding was enhanced in the presence of Ca2+ ASMase was released extracellularly when cells were incubated with C2IIa in the presence of Ca2+ Small interfering RNA (siRNA) knockdown of ASMase reduced C2 toxin-induced cell rounding. ASMase hydrolyzes sphingomyelin to ceramide on the outer leaflet of the membrane at acidic pH. Ceramide was detected in cytoplasmic vesicles containing C2IIa. These results indicated that ASMase activity is necessary for the efficient internalization of C2 toxin into cells. Inhibitors of ASMase may confer protection against infection.
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Crystal structure and structure-based mutagenesis of actin-specific ADP-ribosylating toxin CPILE-a as novel enterotoxin. PLoS One 2017; 12:e0171278. [PMID: 28199340 PMCID: PMC5310789 DOI: 10.1371/journal.pone.0171278] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/17/2017] [Indexed: 01/07/2023] Open
Abstract
Unusual outbreaks of food poisoning in Japan were reported in which Clostridium perfringens was strongly suspected to be the cause based on epidemiological information and fingerprinting of isolates. The isolated strains lack the typical C. perfringens enterotoxin (CPE) but secrete a new enterotoxin consisting of two components: C. perfringens iota-like enterotoxin-a (CPILE-a), which acts as an enzymatic ADP-ribosyltransferase, and CPILE-b, a membrane binding component. Here we present the crystal structures of apo-CPILE-a, NAD+-CPILE-a and NADH-CPILE-a. Though CPILE-a structure has high similarity with known iota toxin-a (Ia) with NAD+, it possesses two extra-long protruding loops from G262-S269 and E402-K408 that are distinct from Ia. Based on the Ia-actin complex structure, we focused on actin-binding interface regions (I-V) including two protruding loops (PT) and examined how mutations in these regions affect the ADP-ribosylation activity of CPILE-a. Though some site-directed mutagenesis studies have already been conducted on the actin binding site of Ia, in the present study, mutagenesis studies were conducted against both α- and β/γ-actin in CPILE-a and Ia. Interestingly, CPILE-a ADP-ribosylates both α- and β/γ-actin, but its sensitivity towards β/γ-actin is 36% compared with α-actin. Our results contrast to that only C2-I ADP-ribosylates β/γ-actin. We also showed that PT-I and two convex-concave interactions in CPILE-a are important for actin binding. The current study is the first detailed analysis of site-directed mutagenesis in the actin binding region of Ia and CPILE-a against both α- and β/γ-actin.
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Toxin Transport by A-B Type of Toxins in Eukaryotic Target Cells and Its Inhibition by Positively Charged Heterocyclic Molecules. Curr Top Microbiol Immunol 2017; 406:229-256. [DOI: 10.1007/82_2017_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Suzuki T, Nagano T, Niwa K, Mutoh S, Uchino M, Tomizawa M, Sagane Y, Watanabe T. Isolation of botulinolysin, a thiol-activated hemolysin, from serotype D Clostridium botulinum: A species-specific gene duplication in Clostridia. Microbiol Res 2016; 193:20-29. [PMID: 27825483 DOI: 10.1016/j.micres.2016.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 07/15/2016] [Accepted: 08/20/2016] [Indexed: 11/29/2022]
Abstract
Botulinolysin (BLY) is a toxin produced by Clostridium botulinum that belongs to a group of thiol-activated hemolysins. In this study, a protein exhibiting hemolytic activity was purified from the culture supernatant of C. botulinum serotype D strain 4947. The purified protein displayed a single band by sodium dodecyl sulfate polyacrylamide gel electrophoresis with a molecular mass of 55kDa, and its N-terminal and internal amino acid sequences exhibited high similarity to a group of thiol-activated hemolysins produced by gram-positive bacteria. Thus, the purified protein was identified as the BLY. Using the nucleotide sequences of previously cloned genes for hemolysins, two types of genes encoding BLY-like proteins were cloned unexpectedly. Molecular modeling analysis indicated that the products of both genes displayed very similar structures, despite the low sequence similarity. In silico screening revealed a specific duplication of the hemolysin gene restricted to serotypes C and D of C. botulinum and their related species among thiol-activated hemolysin-producing bacteria. Our findings provide important insights into the genetic characteristics of pathogenic bacteria.
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Affiliation(s)
- Tomonori Suzuki
- Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan.
| | - Thomas Nagano
- Tokyo International Clinic, 4-18-19 Takanawa, Minato-ku, Tokyo, 108-0074, Japan
| | - Koichi Niwa
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, 099-2493, Japan
| | - Shingo Mutoh
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, 099-2493, Japan
| | - Masataka Uchino
- Department of Applied Biology and Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Motohiro Tomizawa
- Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Yoshimasa Sagane
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, 099-2493, Japan
| | - Toshihiro Watanabe
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, 099-2493, Japan
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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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Di Bella S, Ascenzi P, Siarakas S, Petrosillo N, di Masi A. Clostridium difficile Toxins A and B: Insights into Pathogenic Properties and Extraintestinal Effects. Toxins (Basel) 2016; 8:E134. [PMID: 27153087 PMCID: PMC4885049 DOI: 10.3390/toxins8050134] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile infection (CDI) has significant clinical impact especially on the elderly and/or immunocompromised patients. The pathogenicity of Clostridium difficile is mainly mediated by two exotoxins: toxin A (TcdA) and toxin B (TcdB). These toxins primarily disrupt the cytoskeletal structure and the tight junctions of target cells causing cell rounding and ultimately cell death. Detectable C. difficile toxemia is strongly associated with fulminant disease. However, besides the well-known intestinal damage, recent animal and in vitro studies have suggested a more far-reaching role for these toxins activity including cardiac, renal, and neurologic impairment. The creation of C. difficile strains with mutations in the genes encoding toxin A and B indicate that toxin B plays a major role in overall CDI pathogenesis. Novel insights, such as the role of a regulator protein (TcdE) on toxin production and binding interactions between albumin and C. difficile toxins, have recently been discovered and will be described. Our review focuses on the toxin-mediated pathogenic processes of CDI with an emphasis on recent studies.
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Affiliation(s)
- Stefano Di Bella
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Rome 00149, Italy.
| | - Paolo Ascenzi
- Department of Science, Roma Tre University, Rome 00154, Italy.
| | - Steven Siarakas
- Department of Microbiology and Infectious Diseases, Concord Repatriation General Hospital, Sydney 2139, Australia.
| | - Nicola Petrosillo
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Rome 00149, Italy.
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37
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Bezrukov SM, Nestorovich EM. Inhibiting bacterial toxins by channel blockage. Pathog Dis 2016; 74:ftv113. [PMID: 26656888 PMCID: PMC4830228 DOI: 10.1093/femspd/ftv113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/15/2015] [Accepted: 11/24/2015] [Indexed: 01/01/2023] Open
Abstract
Emergent rational drug design techniques explore individual properties of target biomolecules, small and macromolecule drug candidates, and the physical forces governing their interactions. In this minireview, we focus on the single-molecule biophysical studies of channel-forming bacterial toxins that suggest new approaches for their inhibition. We discuss several examples of blockage of bacterial pore-forming and AB-type toxins by the tailor-made compounds. In the concluding remarks, the most effective rationally designed pore-blocking antitoxins are compared with the small-molecule inhibitors of ion-selective channels of neurophysiology.
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Affiliation(s)
- Sergey M Bezrukov
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Gambale F, Dalla Serra M. In memory of Gianfranco Menestrina. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:443-5. [PMID: 26773391 DOI: 10.1016/j.bbamem.2016.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Franco Gambale
- Institute of Biophysics, National Research Council of Italy, Via De Marini 6, 16149 Genova, Italy
| | - Mauro Dalla Serra
- Institute of Biophysics, National Research Council of Italy & Bruno Kessler Foundation, Via alla Cascata 56/C, 38123 Trento, Italy
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