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Chakroun M, Banyuls N, Bel Y, Escriche B, Ferré J. Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria. Microbiol Mol Biol Rev 2016; 80:329-350. [PMID: 26935135 DOI: 10.1128/mmbr.00060-15.address] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Entomopathogenic bacteria produce insecticidal proteins that accumulate in inclusion bodies or parasporal crystals (such as the Cry and Cyt proteins) as well as insecticidal proteins that are secreted into the culture medium. Among the latter are the Vip proteins, which are divided into four families according to their amino acid identity. The Vip1 and Vip2 proteins act as binary toxins and are toxic to some members of the Coleoptera and Hemiptera. The Vip1 component is thought to bind to receptors in the membrane of the insect midgut, and the Vip2 component enters the cell, where it displays its ADP-ribosyltransferase activity against actin, preventing microfilament formation. Vip3 has no sequence similarity to Vip1 or Vip2 and is toxic to a wide variety of members of the Lepidoptera. Its mode of action has been shown to resemble that of the Cry proteins in terms of proteolytic activation, binding to the midgut epithelial membrane, and pore formation, although Vip3A proteins do not share binding sites with Cry proteins. The latter property makes them good candidates to be combined with Cry proteins in transgenic plants (Bacillus thuringiensis-treated crops [Bt crops]) to prevent or delay insect resistance and to broaden the insecticidal spectrum. There are commercially grown varieties of Bt cotton and Bt maize that express the Vip3Aa protein in combination with Cry proteins. For the most recently reported Vip4 family, no target insects have been found yet.
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Affiliation(s)
- Maissa Chakroun
- ERI de Biotecnología y Biomedicina (Biotecmed),Department of Genetics, Department of Genetics, Universitat de València, Burjassot, Spain
| | - Núria Banyuls
- ERI de Biotecnología y Biomedicina (Biotecmed),Department of Genetics, Department of Genetics, Universitat de València, Burjassot, Spain
| | - Yolanda Bel
- ERI de Biotecnología y Biomedicina (Biotecmed),Department of Genetics, Department of Genetics, Universitat de València, Burjassot, Spain
| | - Baltasar Escriche
- ERI de Biotecnología y Biomedicina (Biotecmed),Department of Genetics, Department of Genetics, Universitat de València, Burjassot, Spain
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (Biotecmed),Department of Genetics, Department of Genetics, Universitat de València, Burjassot, Spain
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102
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Martin-Verstraete I, Peltier J, Dupuy B. The Regulatory Networks That Control Clostridium difficile Toxin Synthesis. Toxins (Basel) 2016; 8:E153. [PMID: 27187475 PMCID: PMC4885068 DOI: 10.3390/toxins8050153] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 05/03/2016] [Accepted: 05/05/2016] [Indexed: 12/19/2022] Open
Abstract
The pathogenic clostridia cause many human and animal diseases, which typically arise as a consequence of the production of potent exotoxins. Among the enterotoxic clostridia, Clostridium difficile is the main causative agent of nosocomial intestinal infections in adults with a compromised gut microbiota caused by antibiotic treatment. The symptoms of C. difficile infection are essentially caused by the production of two exotoxins: TcdA and TcdB. Moreover, for severe forms of disease, the spectrum of diseases caused by C. difficile has also been correlated to the levels of toxins that are produced during host infection. This observation strengthened the idea that the regulation of toxin synthesis is an important part of C. difficile pathogenesis. This review summarizes our current knowledge about the regulators and sigma factors that have been reported to control toxin gene expression in response to several environmental signals and stresses, including the availability of certain carbon sources and amino acids, or to signaling molecules, such as the autoinducing peptides of quorum sensing systems. The overlapping regulation of key metabolic pathways and toxin synthesis strongly suggests that toxin production is a complex response that is triggered by bacteria in response to particular states of nutrient availability during infection.
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Affiliation(s)
- Isabelle Martin-Verstraete
- Laboratoire Pathogenèse des Bactéries Anaérobes, Department of Microbiology, Institut Pasteur, 25 rue du Dr Roux Paris, Paris 75015, France.
- UFR Sciences du vivant, University Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris 75015, France.
| | - Johann Peltier
- Laboratoire Pathogenèse des Bactéries Anaérobes, Department of Microbiology, Institut Pasteur, 25 rue du Dr Roux Paris, Paris 75015, France.
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries Anaérobes, Department of Microbiology, Institut Pasteur, 25 rue du Dr Roux Paris, Paris 75015, France.
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103
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Chloroquine derivatives block the translocation pores and inhibit cellular entry of Clostridium botulinum C2 toxin and Bacillus anthracis lethal toxin. Arch Toxicol 2016; 91:1431-1445. [DOI: 10.1007/s00204-016-1716-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/14/2016] [Indexed: 10/21/2022]
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104
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EGA Protects Mammalian Cells from Clostridium difficile CDT, Clostridium perfringens Iota Toxin and Clostridium botulinum C2 Toxin. Toxins (Basel) 2016; 8:101. [PMID: 27043629 PMCID: PMC4848627 DOI: 10.3390/toxins8040101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 12/18/2022] Open
Abstract
The pathogenic bacteria Clostridium difficile, Clostridium perfringens and Clostridium botulinum produce the binary actin ADP-ribosylating toxins CDT, iota and C2, respectively. These toxins are composed of a transport component (B) and a separate enzyme component (A). When both components assemble on the surface of mammalian target cells, the B components mediate the entry of the A components via endosomes into the cytosol. Here, the A components ADP-ribosylate G-actin, resulting in depolymerization of F-actin, cell-rounding and eventually death. In the present study, we demonstrate that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone (EGA), a compound that protects cells from multiple toxins and viruses, also protects different mammalian epithelial cells from all three binary actin ADP-ribosylating toxins. In contrast, EGA did not inhibit the intoxication of cells with Clostridium difficile toxins A and B, indicating a possible different entry route for this toxin. EGA does not affect either the binding of the C2 toxin to the cells surface or the enzyme activity of the A components of CDT, iota and C2, suggesting that this compound interferes with cellular uptake of the toxins. Moreover, for C2 toxin, we demonstrated that EGA inhibits the pH-dependent transport of the A component across cell membranes. EGA is not cytotoxic, and therefore, we propose it as a lead compound for the development of novel pharmacological inhibitors against clostridial binary actin ADP-ribosylating toxins.
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105
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Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria. Microbiol Mol Biol Rev 2016; 80:329-50. [PMID: 26935135 DOI: 10.1128/mmbr.00060-15] [Citation(s) in RCA: 170] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Entomopathogenic bacteria produce insecticidal proteins that accumulate in inclusion bodies or parasporal crystals (such as the Cry and Cyt proteins) as well as insecticidal proteins that are secreted into the culture medium. Among the latter are the Vip proteins, which are divided into four families according to their amino acid identity. The Vip1 and Vip2 proteins act as binary toxins and are toxic to some members of the Coleoptera and Hemiptera. The Vip1 component is thought to bind to receptors in the membrane of the insect midgut, and the Vip2 component enters the cell, where it displays its ADP-ribosyltransferase activity against actin, preventing microfilament formation. Vip3 has no sequence similarity to Vip1 or Vip2 and is toxic to a wide variety of members of the Lepidoptera. Its mode of action has been shown to resemble that of the Cry proteins in terms of proteolytic activation, binding to the midgut epithelial membrane, and pore formation, although Vip3A proteins do not share binding sites with Cry proteins. The latter property makes them good candidates to be combined with Cry proteins in transgenic plants (Bacillus thuringiensis-treated crops [Bt crops]) to prevent or delay insect resistance and to broaden the insecticidal spectrum. There are commercially grown varieties of Bt cotton and Bt maize that express the Vip3Aa protein in combination with Cry proteins. For the most recently reported Vip4 family, no target insects have been found yet.
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106
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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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107
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A novel Hsp70 inhibitor prevents cell intoxication with the actin ADP-ribosylating Clostridium perfringens iota toxin. Sci Rep 2016; 6:20301. [PMID: 26839186 PMCID: PMC4738285 DOI: 10.1038/srep20301] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/30/2015] [Indexed: 12/14/2022] Open
Abstract
Hsp70 family proteins are folding helper proteins involved in a wide variety of cellular pathways. Members of this family interact with key factors in signal transduction, transcription, cell-cycle control, and stress response. Here, we developed the first Hsp70 low molecular weight inhibitor specifically targeting the peptide binding site of human Hsp70. After demonstrating that the inhibitor modulates the Hsp70 function in the cell, we used the inhibitor to show for the first time that the stress-inducible chaperone Hsp70 functions as molecular component for entry of a bacterial protein toxin into mammalian cells. Pharmacological inhibition of Hsp70 protected cells from intoxication with the binary actin ADP-ribosylating iota toxin from Clostridium perfringens, the prototype of a family of enterotoxins from pathogenic Clostridia and inhibited translocation of its enzyme component across cell membranes into the cytosol. This finding offers a starting point for novel therapeutic strategies against certain bacterial toxins.
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108
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Kuan SL, Förtsch C, Ng DYW, Fischer S, Tokura Y, Liu W, Wu Y, Koynov K, Barth H, Weil T. A Supramolecular Approach toward Bioinspired PAMAM-Dendronized Fusion Toxins. Macromol Biosci 2016; 16:803-10. [PMID: 26833574 DOI: 10.1002/mabi.201500417] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 12/28/2015] [Indexed: 11/07/2022]
Abstract
Nature has provided a highly optimized toolbox in bacterial endotoxins with precise functions dictated by their clear structural division. Inspired by this streamlined design, a supramolecular approach capitalizing on the strong biomolecular (streptavidin (SA))-biotin interactions is reported herein to prepare two multipartite fusion constructs, which involves the generation 2.0 (D2) or generation 3.0 (D3) polyamidoamine-dendronized transporter proteins (dendronized streptavidin (D3SA) and dendronized human serum albumin (D2HSA)) non-covalently fused to the C3bot1 enzyme from Clostridium botulinum, a potent and specific Rho-inhibitor. The fusion constructs, D3SA-C3 and D2HSA-C3, represent the first examples of dendronized protein transporters that are fused to the C3 enzyme, and it is successfully demonstrated that the C3 Rho-inhibitor is delivered into the cytosol of mammalian cells as determined from the characteristic C3-mediated changes in cell morphology and confocal microscopy. The design circumvents the low uptake of the C3 enzyme by eukaryotic cells and holds great promise for reprogramming the properties of toxin enzymes using a supramolecular approach to broaden their therapeutic applications.
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Affiliation(s)
- Seah Ling Kuan
- Institute of Organic Chemistry III - Macromolecular Chemistry & Biomaterials, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Christina Förtsch
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - David Yuen Wah Ng
- Institute of Organic Chemistry III - Macromolecular Chemistry & Biomaterials, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Stephan Fischer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Yu Tokura
- Institute of Organic Chemistry III - Macromolecular Chemistry & Biomaterials, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Weina Liu
- Institute of Organic Chemistry III - Macromolecular Chemistry & Biomaterials, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Yuzhou Wu
- Institute of Organic Chemistry III - Macromolecular Chemistry & Biomaterials, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Kaloian Koynov
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Tanja Weil
- Institute of Organic Chemistry III - Macromolecular Chemistry & Biomaterials, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
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109
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Sun J, Jacquez P. Roles of Anthrax Toxin Receptor 2 in Anthrax Toxin Membrane Insertion and Pore Formation. Toxins (Basel) 2016; 8:34. [PMID: 26805886 PMCID: PMC4773787 DOI: 10.3390/toxins8020034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 12/04/2022] Open
Abstract
Interaction between bacterial toxins and cellular surface receptors is an important component of the host-pathogen interaction. Anthrax toxin protective antigen (PA) binds to the cell surface receptor, enters the cell through receptor-mediated endocytosis, and forms a pore on the endosomal membrane that translocates toxin enzymes into the cytosol of the host cell. As the major receptor for anthrax toxin in vivo, anthrax toxin receptor 2 (ANTXR2) plays an essential role in anthrax toxin action by providing the toxin with a high-affinity binding anchor on the cell membrane and a path of entry into the host cell. ANTXR2 also acts as a molecular clamp by shifting the pH threshold of PA pore formation to a more acidic pH range, which prevents premature pore formation at neutral pH before the toxin reaches the designated intracellular location. Most recent studies have suggested that the disulfide bond in the immunoglobulin (Ig)-like domain of ANTXR2 plays an essential role in anthrax toxin action. Here we will review the roles of ANTXR2 in anthrax toxin action, with an emphasis on newly updated knowledge.
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Affiliation(s)
- Jianjun Sun
- Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA.
| | - Pedro Jacquez
- Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA.
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110
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Host Cell Chaperones Hsp70/Hsp90 and Peptidyl-Prolyl Cis/Trans Isomerases Are Required for the Membrane Translocation of Bacterial ADP-Ribosylating Toxins. Curr Top Microbiol Immunol 2016; 406:163-198. [PMID: 27197646 DOI: 10.1007/82_2016_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacterial ADP-ribosylating toxins are the causative agents for several severe human and animal diseases such as diphtheria, cholera, or enteric diseases. They display an AB-type structure: The enzymatically active A-domain attaches to the binding/translocation B-domain which then binds to a receptor on the cell surface. After receptor-mediated endocytosis, the B-domain facilitates the membrane translocation of the unfolded A-domain into the host cell cytosol. Here, the A-domain transfers an ADP-ribose moiety onto its specific substrate which leads to characteristic cellular effects and thus to severe clinical symptoms. Since the A-domain has to reach the cytosol to achieve a cytotoxic effect, the membrane translocation represents a crucial step during toxin uptake. Host cell chaperones including Hsp90 and protein-folding helper enzymes of the peptidyl-prolyl cis/trans isomerase (PPIase) type facilitate this membrane translocation of the unfolded A-domain for ADP-ribosylating toxins but not for toxins with a different enzyme activity. This review summarizes the uptake mechanisms of the ADP-ribosylating clostridial binary toxins, diphtheria toxin (DT) and cholera toxin (CT), with a special focus on the interaction of these toxins with the chaperones Hsp90 and Hsp70 and PPIases of the cyclophilin and FK506-binding protein families during the membrane translocation of their ADP-ribosyltransferase domains into the host cell cytosol. Moreover, the medical implications of host cell chaperones and PPIases as new drug targets for the development of novel therapeutic strategies against diseases caused by bacterial ADP-ribosylating toxins are discussed.
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111
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Schwan C, Aktories K. Formation of Nanotube-Like Protrusions, Regulation of Septin Organization and Re-guidance of Vesicle Traffic by Depolymerization of the Actin Cytoskeleton Induced by Binary Bacterial Protein Toxins. Curr Top Microbiol Immunol 2016; 399:35-51. [PMID: 27726005 DOI: 10.1007/82_2016_25] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A large group of bacterial protein toxins, including binary ADP-ribosylating toxins, modify actin at arginine-177, thereby actin polymerization is blocked and the actin cytoskeleton is redistributed. Modulation of actin functions largely affects other components of the cytoskeleton, especially microtubules and septins. Here, recent findings about the functional interconnections of the actin cytoskeleton with microtubules and septins, affected by bacterial toxins, are reviewed.
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Affiliation(s)
- Carsten Schwan
- Institute for Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs University of Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Klaus Aktories
- Institute for Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs University of Freiburg, Albertstr. 25, 79104, Freiburg, Germany.
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112
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Belyy A, Tabakova I, Lang AE, Jank T, Belyi Y, Aktories K. Roles of Asp179 and Glu270 in ADP-Ribosylation of Actin by Clostridium perfringens Iota Toxin. PLoS One 2015; 10:e0145708. [PMID: 26713879 PMCID: PMC4699905 DOI: 10.1371/journal.pone.0145708] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 12/08/2015] [Indexed: 12/19/2022] Open
Abstract
Clostridium perfringens iota toxin is a binary toxin composed of the enzymatically active component Ia and receptor binding component Ib. Ia is an ADP-ribosyltransferase, which modifies Arg177 of actin. The previously determined crystal structure of the actin-Ia complex suggested involvement of Asp179 of actin in the ADP-ribosylation reaction. To gain more insights into the structural requirements of actin to serve as a substrate for toxin-catalyzed ADP-ribosylation, we engineered Saccharomyces cerevisiae strains, in which wild type actin was replaced by actin variants with substitutions in residues located on the Ia-actin interface. Expression of the actin mutant Arg177Lys resulted in complete resistance towards Ia. Actin mutation of Asp179 did not change Ia-induced ADP-ribosylation and growth inhibition of S. cerevisiae. By contrast, substitution of Glu270 of actin inhibited the toxic action of Ia and the ADP-ribosylation of actin. In vitro transcribed/translated human β-actin confirmed the crucial role of Glu270 in ADP-ribosylation of actin by Ia.
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Affiliation(s)
- Alexander Belyy
- Gamaleya Research Institute, Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Alexander E. Lang
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Thomas Jank
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Yury Belyi
- Gamaleya Research Institute, Moscow, Russia
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany
| | - Klaus Aktories
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg, Germany
- * E-mail:
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113
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Wang S, Rustandi RR, Lancaster C, Hong LG, Thiriot DS, Xie J, Secore S, Kristopeit A, Wang SC, Heinrichs JH. Toxicity assessment of Clostridium difficile toxins in rodent models and protection of vaccination. Vaccine 2015; 34:1319-23. [PMID: 26614590 DOI: 10.1016/j.vaccine.2015.11.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 11/30/2022]
Abstract
Clostridium difficile is the leading cause of hospital-acquired diarrhea, also known as C. difficile associated diarrhea. The two major toxins, toxin A and toxin B are produced by most C. difficile bacteria, but some strains, such as BI/NAP1/027 isolates, produce a third toxin called binary toxin. The precise biological role of binary toxin is not clear but it has been shown to be a cytotoxin for Vero cells. We evaluated the toxicity of these toxins in mice and hamsters and found that binary toxin causes death in both animals similar to toxins A and B. Furthermore, immunization of mice with mutant toxoids of all three toxins provided protection upon challenge with native toxins. These results support the concept that binary toxin contributes to the pathogenicity of C. difficile and provide a method for monitoring the toxicity of binary toxin components in vaccines.
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Affiliation(s)
- Su Wang
- Vaccine Basic Research, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Richard R Rustandi
- Vaccine Analytical Development, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA.
| | - Catherine Lancaster
- Vaccine Analytical Development, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Laura G Hong
- Vaccine Analytical Development, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - David S Thiriot
- Vaccine Drug Product Development, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Jinfu Xie
- Vaccine Basic Research, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Susan Secore
- Vaccine Basic Research, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Adam Kristopeit
- Vaccine Process Development, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Sheng-Ching Wang
- Vaccine Process Development, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Jon H Heinrichs
- Vaccine Basic Research, Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
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114
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Ünal CM, Steinert M. Novel therapeutic strategies for Clostridium difficile infections. Expert Opin Ther Targets 2015; 20:269-85. [PMID: 26565670 DOI: 10.1517/14728222.2016.1090428] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION In recent years, Clostridium difficile has become the primary cause of antibiotic-associated diarrhea and pseudomembranous colitis, resulting in long and complicated hospital stays that represent a serious burden for patients as well as health care systems. Currently, conservative treatment of C. difficile infection (CDI) relies on the antibiotics vancomycin, metronidazole or fidaxomicin, or in case of multiple recurrences, fecal microbiota transplantation (FMT). AREAS COVERED The fast-spreading, epidemic nature of this pathogen urgently necessitates the search for alternative treatment strategies as well as antibiotic targets. Accordingly, in this review, we highlight the recent findings regarding virulence associated traits of C. difficile, evaluate their potential as alternative drug targets, and present current efforts in designing inhibitory compounds, with the aim of pointing out possibilities for future treatment strategies. EXPERT OPINION Increased attention on systematic analysis of the virulence mechanisms of C. difficile has already led to the identification of several alternative drug targets. In the future, applying state of the art 'omics' and the development of novel infection models that mimic the human gut, a highly complex ecological niche, will unveil the genomic and metabolic plasticity of this pathogen and will certainly help dealing with future challenges.
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Affiliation(s)
- Can M Ünal
- a 1 Technische Universität Braunschweig, Institut für Mikrobiologie , Spielmannstr. 7, D-38106, Braunschweig, Germany ; .,b 2 Türk-Alman Üniversitesi, Fen Fakültesi , Şahinkaya Cad. 86, 34820, Istanbul, Turkey
| | - Michael Steinert
- a 1 Technische Universität Braunschweig, Institut für Mikrobiologie , Spielmannstr. 7, D-38106, Braunschweig, Germany ; .,c 3 Helmholtz Centre for Infection Research , Mascheroder Weg 1, 38124, Braunschweig, Germany
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115
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Zhao S, Ghose-Paul C, Zhang K, Tzipori S, Sun X. Immune-based treatment and prevention of Clostridium difficile infection. Hum Vaccin Immunother 2015; 10:3522-30. [PMID: 25668664 DOI: 10.4161/21645515.2014.980193] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Clostridium difficile (C. difficile) causes over 500,000 infections per year in the US, with an estimated 15,000 deaths and an estimated cost of $1-3 billion. Moreover, a continual rise in the incidence of severe C. difficile infection (CDI) has been observed worldwide. Currently, standard treatment for CDI is the administration of antibiotics. While effective, these treatments do not prevent and may contribute to a disease recurrence rate of 15-35%. Prevention of recurrence is one of the most challenging aspects in the field. A better knowledge of the molecular mechanisms of the disease, the host immune response and identification of key virulence factors of C. difficilenow permits the development of immune-based therapies. Antibodies specific for C. difficile toxins have been shown to effectively treat CDI and prevent disease relapse in animal models and in humans. Vaccination has been recognized as the most cost-effective treatment/prevention for CDI. This review will summarize CDI transmission, epidemiology, major virulent factors and highlights the rational and the development of immune-based approaches against this remerging threat.
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Key Words
- AAD, antibiotic-associated diarrhea
- CDI, Clostridium difficile infection
- CPD, cysteine proteinase domain
- GTD, glucosyltransferase domain
- HuMabs, human monoclonal antibodies
- IVIG, intravenous immunoglobulin
- RBD, receptor binding domain
- SLP, surface-layer protein
- TMD, transmembrane domain
- bacterial toxins
- clostridium difficile infection (CDI)
- immunotherapy
- mAb, monoclonal antibody
- monoclonal antibody
- vaccine
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Affiliation(s)
- Song Zhao
- a Department of Infectious Diseases and Global Health ; Tufts University Cummings School of Veterinary Medicine ; North Grafton , MA USA
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116
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Peng X, Sun J. Mechanism of ESAT-6 membrane interaction and its roles in pathogenesis of Mycobacterium tuberculosis. Toxicon 2015; 116:29-34. [PMID: 26456678 DOI: 10.1016/j.toxicon.2015.10.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/21/2015] [Accepted: 10/05/2015] [Indexed: 10/22/2022]
Abstract
The 6-kDa early secreted antigenic target (ESAT-6; EsxA) of Mycobacterium tuberculosis was first identified as a potent T-cell antigen, and it is now recognized as a pore-forming toxin that is essential for virulence of M. tuberculosis. ESAT-6 is secreted through the ESX-1 secretion system (Type VII) of M. tuberculosis and has been implicated to mediate mycobacterial cytosolic translocation within the host macrophages by rupturing the phagosomal membranes. Recent studies have made significant progresses in understanding of the mechanism of ESAT-6 membrane interaction and its role in M. tuberculosis pathogenesis, but important questions still remain to be answered. Here, we summarize the current progress in study of ESAT-6 membrane interaction and its roles in pathogenesis and discuss some of the key remaining questions for future investigation.
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Affiliation(s)
- Xiuli Peng
- Key Laboratory Agriculture Animal Genetics, Breeding and Reproduction, Ministry of Education, Huazhong Agriculture University, Wuhan, 430070, China
| | - Jianjun Sun
- Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA.
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117
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Lekakarn H, Promdonkoy B, Boonserm P. Interaction of Lysinibacillus sphaericus binary toxin with mosquito larval gut cells: Binding and internalization. J Invertebr Pathol 2015; 132:125-131. [PMID: 26408968 DOI: 10.1016/j.jip.2015.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 07/29/2015] [Accepted: 09/23/2015] [Indexed: 01/02/2023]
Abstract
The binary toxin produced by Lysinibacillus sphaericus is composed of BinA and BinB subunits. Together, but not separately, the two subunits are highly toxic to Culex quinquefasciatus larvae, but show no toxicity to Aedes aegypti. The molecular mechanism underlying intoxication has not been clearly elucidated. The present study compares the binding and the internalization of binary toxin into the midgut epithelial cells of susceptible C. quinquefasciatus mosquito larvae with those of Bin-refractory A. aegypti. The guts from larvae fed with fluorescently labeled toxin were dissected and analyzed using a confocal laser scanning microscope. When fed with a mixture of both components, co-localization of BinA and BinB was detected both on the cell surface and in the cytoplasm of Culex larval gut cells. However, administration of BinA alone resulted in localization only on the cell membrane, whereas BinB alone was detected both on the cell membrane and inside the cytoplasm. In contrast, when a mixture of both components, or each individual component, was fed to Aedes larvae, BinA and BinB were unable to reach the cytoplasm and were localized only on the cell membrane. These results are consistent with the suggestion that the internalization of BinA is essential for toxicity, and that BinB is required for this internalization into susceptible larval gut cells.
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Affiliation(s)
- Hataikarn Lekakarn
- Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom 73170, Thailand
| | - Boonhiang Promdonkoy
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Pahonyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Panadda Boonserm
- Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom 73170, Thailand.
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118
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Pore-forming activity of clostridial binary toxins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:512-25. [PMID: 26278641 DOI: 10.1016/j.bbamem.2015.08.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/13/2015] [Accepted: 08/11/2015] [Indexed: 11/24/2022]
Abstract
Clostridial binary toxins (Clostridium perfringens Iota toxin, Clostridium difficile transferase, Clostridium spiroforme toxin, Clostridium botulinum C2 toxin) as Bacillus binary toxins, including Bacillus anthracis toxins consist of two independent proteins, one being the binding component which mediates the internalization into cell of the intracellularly active component. Clostridial binary toxins induce actin cytoskeleton disorganization through mono-ADP-ribosylation of globular actin and are responsible for enteric diseases. Clostridial and Bacillus binary toxins share structurally and functionally related binding components which recognize specific cell receptors, oligomerize, form pores in endocytic vesicle membrane, and mediate the transport of the enzymatic component into the cytosol. Binding components retain the global structure of pore-forming toxins (PFTs) from the cholesterol-dependent cytotoxin family such as perfringolysin. However, their pore-forming activity notably that of clostridial binding components is more related to that of heptameric PFT family including aerolysin and C. perfringens epsilon toxin. This review focuses upon pore-forming activity of clostridial binary toxins compared to other related PFTs. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
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119
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Fang RH, Luk BT, Hu CMJ, Zhang L. Engineered nanoparticles mimicking cell membranes for toxin neutralization. Adv Drug Deliv Rev 2015; 90:69-80. [PMID: 25868452 DOI: 10.1016/j.addr.2015.04.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/08/2015] [Accepted: 04/01/2015] [Indexed: 11/27/2022]
Abstract
Protein toxins secreted from pathogenic bacteria and venomous animals rely on multiple mechanisms to overcome the cell membrane barrier to inflict their virulence effect. A promising therapeutic concept toward developing a broadly applicable anti-toxin platform is to administer cell membrane mimics as decoys to sequester these virulence factors. As such, lipid membrane-based nanoparticulates are an ideal candidate given their structural similarity to cellular membranes. This article reviews the virulence mechanisms employed by toxins at the cell membrane interface and highlights the application of cell-membrane mimicking nanoparticles as toxin decoys for systemic detoxification. In addition, the implication of particle/toxin nanocomplexes in the development of toxoid vaccines is discussed.
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120
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Xiong S, Tang Q, Liang X, Zhou T, Yang J, Liu P, Chen Y, Wang C, Feng Z, Zhu J. A Novel Chimeric Anti-PA Neutralizing Antibody for Postexposure Prophylaxis and Treatment of Anthrax. Sci Rep 2015; 5:11776. [PMID: 26134518 PMCID: PMC4488766 DOI: 10.1038/srep11776] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 05/28/2015] [Indexed: 12/11/2022] Open
Abstract
Anthrax is a highly lethal infectious disease caused by the bacterium Bacillus anthracis, and the associated shock is closely related to the lethal toxin (LeTx) produced by the bacterium. The central role played by the 63 kDa protective antigen (PA63) region of LeTx in the pathophysiology of anthrax makes it an excellent therapeutic target. In the present study, a human/murine chimeric IgG mAb, hmPA6, was developed by inserting murine antibody variable regions into human constant regions using antibody engineering technology. hmPA6 expressed in 293F cells could neutralize LeTx both in vitro and in vivo. At a dose of 0.3 mg/kg, it could protect all tested rats from a lethal dose of LeTx. Even administration of 0.6 mg/kg hmPA6 48 h before LeTx challenge protected all tested rats. The results indicate that hmPA6 is a potential candidate for clinical application in anthrax treatment.
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Affiliation(s)
- Siping Xiong
- 1] Department of Pathology, Nanjing Medical University, Nanjing 210029, China [2] Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing 210029, China
| | - Qi Tang
- Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing 210029, China
| | - Xudong Liang
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206 China
| | - Tingting Zhou
- Huadong Medical Institute of Biotechniques, Nanjing 210002, China
| | - Jin Yang
- Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing 210029, China
| | - Peng Liu
- Huadong Medical Institute of Biotechniques, Nanjing 210002, China
| | - Ya Chen
- 1] Department of Pathology, Nanjing Medical University, Nanjing 210029, China [2] Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing 210029, China
| | - Changjun Wang
- Huadong Medical Institute of Biotechniques, Nanjing 210002, China
| | - Zhenqing Feng
- 1] Department of Pathology, Nanjing Medical University, Nanjing 210029, China [2] Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing 210029, China
| | - Jin Zhu
- 1] Huadong Medical Institute of Biotechniques, Nanjing 210002, China [2] Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing 210029, China
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121
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Micropatterned macrophage analysis reveals global cytoskeleton constraints induced by Bacillus anthracis edema toxin. Infect Immun 2015; 83:3114-25. [PMID: 26015478 DOI: 10.1128/iai.00479-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 05/16/2015] [Indexed: 12/20/2022] Open
Abstract
Bacillus anthracis secretes the edema toxin (ET) that disrupts the cellular physiology of endothelial and immune cells, ultimately affecting the adherens junction integrity of blood vessels that in turn leads to edema. The effects of ET on the cytoskeleton, which is critical in cell physiology, have not been described thus far on macrophages. In this study, we have developed different adhesive micropatterned surfaces (L and crossbow) to control the shape of bone marrow-derived macrophages (BMDMs) and primary peritoneal macrophages. We found that macrophage F-actin cytoskeleton adopts a specific polar organization slightly different from classical human HeLa cells on the micropatterns. Moreover, ET induced a major quantitative reorganization of F-actin within 16 h with a collapse at the nonadhesive side of BMDMs along the nucleus. There was an increase in size and deformation into a kidney-like shape, followed by a decrease in size that correlates with a global cellular collapse. The collapse of F-actin was correlated with a release of focal adhesion on the patterns and decreased cell size. Finally, the cell nucleus was affected by actin reorganization. By using this technology, we could describe many previously unknown macrophage cellular dysfunctions induced by ET. This novel tool could be used to analyze more broadly the effects of toxins and other virulence factors that target the cytoskeleton.
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122
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Advances in Anthrax Detection: Overview of Bioprobes and Biosensors. Appl Biochem Biotechnol 2015; 176:957-77. [PMID: 25987133 DOI: 10.1007/s12010-015-1625-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 04/08/2015] [Indexed: 12/22/2022]
Abstract
Anthrax is an infectious disease caused by Bacillus anthracis. Although anthrax commonly affects domestic and wild animals, it causes a rare but lethal infection in humans. A variety of techniques have been introduced and evaluated to detect anthrax using cultures, polymerase chain reaction, and immunoassays to address the potential threat of anthrax being used as a bioweapon. The high-potential harm of anthrax in bioterrorism requires sensitive and specific detection systems that are rapid, field-ready, and real-time monitoring. Here, we provide a systematic overview of anthrax detection probes with their potential applications in various ultra-sensitive diagnostic systems.
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123
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Noskov AN. [Molecular model of anthrax toxin translocation into target-cells]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2015; 40:399-404. [PMID: 25898749 DOI: 10.1134/s1068162014040098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anthrax toxin is formed from three components: protective antigen (PA), lethal (LF) and edema (EF) factors. PA83 is cleaved by cell surface protease furin to produce a 63-kDa fragment (PA63). PA63 and LF/EF molecules are assembled to anthrax toxin complexes: oligomer PA63 x 7 + LF/EF x 3. Assembly is occurred during of binding with cellular receptor or near surface of target-cell. This toxin complex forms pore and induces receptor-mediated endocytosis. Formed endosome consists extracellular liquid with LF/EF and membrane-associated ferments (H+ and K+/Na+-ATPases) and proteins (receptors and others). H+ concentration is increased into endosome as result of K/Na-ATPase-dependent- activity of H+-ATPase. Difference of potentials (between endosome and intracellular liquid) is increased and LF/EF molecules are moved to pore and bound with PA63-oligomer to PA63 x 7 + LF/EF x 7 and full block pore (ion-selective channel). Endosome is increased in volume and induces increasing of PA63-oligomer pore to.size of effector complex: LF/EF x 7 + PAl7 x 7 = 750 kDa. Effector complex is translocated from endosome to cytosol by means high difference of potentials (H+) and dissociates from PA47 x 7 complex after cleavage of FFD315-sait by intracellular chymotrypsin-like proteases in all 7 molecules PA63. PA47 x 7 complex (strongly fixed in membrane with debris of hydrophobic loops) return into endosome and pore is destroyed. Endosome pH is decreased rapidly and PA47 x 7 complex is destroyed by endosomal/lysosomal proteases. Receptor-mediated endocytosis is ended by endosome recycling in cell-membrane.
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124
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Hemmasi S, Czulkies BA, Schorch B, Veit A, Aktories K, Papatheodorou P. Interaction of the Clostridium difficile Binary Toxin CDT and Its Host Cell Receptor, Lipolysis-stimulated Lipoprotein Receptor (LSR). J Biol Chem 2015; 290:14031-44. [PMID: 25882847 DOI: 10.1074/jbc.m115.650523] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Indexed: 12/17/2022] Open
Abstract
CDT (Clostridium difficile transferase) is a binary, actin ADP-ribosylating toxin frequently associated with hypervirulent strains of the human enteric pathogen C. difficile, the most serious cause of antibiotic-associated diarrhea and pseudomembranous colitis. CDT leads to the collapse of the actin cytoskeleton and, eventually, to cell death. Low doses of CDT result in the formation of microtubule-based protrusions on the cell surface that increase the adherence and colonization of C. difficile. The lipolysis-stimulated lipoprotein receptor (LSR) is the host cell receptor for CDT, and our aim was to gain a deeper insight into the interplay between both proteins. We show that CDT interacts with the extracellular, Ig-like domain of LSR with an affinity in the nanomolar range. We identified LSR splice variants in the colon carcinoma cell line HCT116 and disrupted the LSR gene in these cells by applying the CRISPR-Cas9 technology. LSR truncations ectopically expressed in LSR knock-out cells indicated that intracellular parts of LSR are not essential for plasma membrane targeting of the receptor and cellular uptake of CDT. By generating a series of N- and C-terminal truncations of the binding component of CDT (CDTb), we found that amino acids 757-866 of CDTb are sufficient for binding to LSR. With a transposon-based, random mutagenesis approach, we identified potential LSR-interacting epitopes in CDTb. This study increases our understanding about the interaction between CDT and its receptor LSR, which is key to the development of anti-toxin strategies for preventing cell entry of the toxin.
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Affiliation(s)
- Sarah Hemmasi
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Fakultät für Biologie
| | - Bernd A Czulkies
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Hermann Staudinger Graduate School
| | - Björn Schorch
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Fakultät für Biologie, the Spemann Graduate School of Biology and Medicine, and
| | - Antonia Veit
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie
| | - Klaus Aktories
- From the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, the Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
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125
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Microbial peptidyl-prolyl cis/trans isomerases (PPIases): virulence factors and potential alternative drug targets. Microbiol Mol Biol Rev 2015; 78:544-71. [PMID: 25184565 DOI: 10.1128/mmbr.00015-14] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Initially discovered in the context of immunomodulation, peptidyl-prolyl cis/trans isomerases (PPIases) were soon identified as enzymes catalyzing the rate-limiting protein folding step at peptidyl bonds preceding proline residues. Intense searches revealed that PPIases are a superfamily of proteins consisting of three structurally distinguishable families with representatives in every described species of prokaryote and eukaryote and, recently, even in some giant viruses. Despite the clear-cut enzymatic activity and ubiquitous distribution of PPIases, reports on solely PPIase-dependent biological roles remain scarce. Nevertheless, they have been found to be involved in a plethora of biological processes, such as gene expression, signal transduction, protein secretion, development, and tissue regeneration, underscoring their general importance. Hence, it is not surprising that PPIases have also been identified as virulence-associated proteins. The extent of contribution to virulence is highly variable and dependent on the pleiotropic roles of a single PPIase in the respective pathogen. The main objective of this review is to discuss this variety in virulence-related bacterial and protozoan PPIases as well as the involvement of host PPIases in infectious processes. Moreover, a special focus is given to Legionella pneumophila macrophage infectivity potentiator (Mip) and Mip-like PPIases of other pathogens, as the best-characterized virulence-related representatives of this family. Finally, the potential of PPIases as alternative drug targets and first tangible results are highlighted.
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126
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Redondo LM, Carrasco JMD, Redondo EA, Delgado F, Miyakawa MEF. Clostridium perfringens type E virulence traits involved in gut colonization. PLoS One 2015; 10:e0121305. [PMID: 25799452 PMCID: PMC4370460 DOI: 10.1371/journal.pone.0121305] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 01/30/2015] [Indexed: 02/04/2023] Open
Abstract
Clostridium perfringens type E disease in ruminants has been characterized by hemorrhagic enteritis or sudden death. Although type E isolates are defined by the production of alpha and iota toxin, little is known about the pathogenesis of C. perfringens type E infections. Thus far, the role of iota toxin as a virulence factor is unknown. In this report, iota toxin showed positive effects on adherence and colonization of C. perfringens type E while having negative effect on the adherence of type A cells. In-vitro and in-vivo models suggest that toxinotype E would be particularly adapted to exploit the changes induced by iota toxin in the surface of epithelial cells. In addition, type E strains produce metabolites that affected the growth of potential intra-specific competitors. These results suggest that the alteration of the enterocyte morphology induced by iota toxin concomitantly with the specific increase of type E cell adhesion and the strong intra-specific growth inhibition of other strains could be competitive traits inherent to type E isolates that improve its fitness within the bovine gut environment.
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Affiliation(s)
- Leandro M. Redondo
- Instituto de Patobiología, Centro Nacional de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Juan M. Díaz Carrasco
- Instituto de Patobiología, Centro Nacional de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Enzo A. Redondo
- Instituto de Patobiología, Centro Nacional de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Fernando Delgado
- Instituto de Patobiología, Centro Nacional de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Castelar, Buenos Aires, Argentina
| | - Mariano E. Fernández Miyakawa
- Instituto de Patobiología, Centro Nacional de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
- * E-mail:
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127
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Engineering therapeutic proteins for cell entry: the natural approach. Trends Biotechnol 2015; 33:163-71. [DOI: 10.1016/j.tibtech.2014.12.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/08/2014] [Accepted: 12/16/2014] [Indexed: 02/04/2023]
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128
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Selection of nanobodies that block the enzymatic and cytotoxic activities of the binary Clostridium difficile toxin CDT. Sci Rep 2015; 5:7850. [PMID: 25597743 PMCID: PMC4297958 DOI: 10.1038/srep07850] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 12/16/2014] [Indexed: 01/01/2023] Open
Abstract
The spore-forming gut bacterium Clostridium difficile is the leading cause of antibiotic-associated diarrhea in hospitalized patients. The major virulence factors are two large glucosylating cytotoxins. Hypervirulent strains (e.g. ribotype 027) with higher morbidity and mortality additionally produce the binary CDT toxin (Clostridium difficile transferase) that ADP-ribosylates actin and induces microtubule-based cell protrusions. Nanobodies are robust single domain antibodies derived from camelid heavy chain antibodies. Here we report the generation of functional nanobodies against the enzymatic CDTa and the heptameric receptor binding subunit CDTb. The nanobodies were obtained from a variable-domain repertoire library isolated from llamas immunized with recombinant CDTa or CDTb. Five CDTa-specific nanobodies blocked CDTa-mediated ADP-ribosylation of actin. Three CDTa-specific and two CDTb-specific nanobodies neutralized the cytotoxicity of CDTa+b. These nanobodies hold promise as new tools for research, diagnosis and therapy of C. difficile associated disease.
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129
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Ünal CM, Steinert M. FKBPs in bacterial infections. Biochim Biophys Acta Gen Subj 2014; 1850:2096-102. [PMID: 25529296 DOI: 10.1016/j.bbagen.2014.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 12/11/2014] [Accepted: 12/13/2014] [Indexed: 02/05/2023]
Abstract
BACKGROUND FK506-binding proteins (FKBPs) contain a domain with peptidyl-prolyl-cis/trans-isomerase (PPIase) activity and bind the immunosuppressive drugs FK506 and rapamycin. FKBPs belong to the immunophilin family and are found in eukaryotes and bacteria. SCOPE OF REVIEW In this review we describe two major groups of bacterial virulence-associated FKBPs, the trigger factor and Mip-like PPIases. Moreover, we discuss the contribution of host FKBPs in bacterial infection processes. MAJOR CONCLUSIONS Since PPIases are regarded as alternative antiinfective drug targets we highlight current research strategies utilizing pipecolinic acid and cycloheximide derivatives as well as substrate based inhibitors. GENERAL SIGNIFICANCE The current research strategies suggest a beneficial synergism of drug development and basic research. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
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Affiliation(s)
- Can M Ünal
- Türk-Alman Üniversitesi, Fen Fakültesi, Istanbul, Turkey; Technische Universität Braunschweig, Institut für Mikrobiologie, Braunschweig, Germany
| | - Michael Steinert
- Technische Universität Braunschweig, Institut für Mikrobiologie, Braunschweig, Germany; Helmholtz Centre for Infection Research, Braunschweig, Germany.
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130
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Palma L, Muñoz D, Berry C, Murillo J, Caballero P. Bacillus thuringiensis toxins: an overview of their biocidal activity. Toxins (Basel) 2014; 6:3296-325. [PMID: 25514092 PMCID: PMC4280536 DOI: 10.3390/toxins6123296] [Citation(s) in RCA: 349] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/07/2014] [Accepted: 12/03/2014] [Indexed: 11/16/2022] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram positive, spore-forming bacterium that synthesizes parasporal crystalline inclusions containing Cry and Cyt proteins, some of which are toxic against a wide range of insect orders, nematodes and human-cancer cells. These toxins have been successfully used as bioinsecticides against caterpillars, beetles, and flies, including mosquitoes and blackflies. Bt also synthesizes insecticidal proteins during the vegetative growth phase, which are subsequently secreted into the growth medium. These proteins are commonly known as vegetative insecticidal proteins (Vips) and hold insecticidal activity against lepidopteran, coleopteran and some homopteran pests. A less well characterized secretory protein with no amino acid similarity to Vip proteins has shown insecticidal activity against coleopteran pests and is termed Sip (secreted insecticidal protein). Bin-like and ETX_MTX2-family proteins (Pfam PF03318), which share amino acid similarities with mosquitocidal binary (Bin) and Mtx2 toxins, respectively, from Lysinibacillus sphaericus, are also produced by some Bt strains. In addition, vast numbers of Bt isolates naturally present in the soil and the phylloplane also synthesize crystal proteins whose biological activity is still unknown. In this review, we provide an updated overview of the known active Bt toxins to date and discuss their activities.
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Affiliation(s)
- Leopoldo Palma
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Campus Arrosadía, Mutilva Baja, 31192 Navarra, Spain.
| | - Delia Muñoz
- Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona, 31006 Navarra, Spain.
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
| | - Jesús Murillo
- Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona, 31006 Navarra, Spain.
| | - Primitivo Caballero
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Campus Arrosadía, Mutilva Baja, 31192 Navarra, Spain.
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131
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Clostridial pore-forming toxins: Powerful virulence factors. Anaerobe 2014; 30:220-38. [DOI: 10.1016/j.anaerobe.2014.05.014] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/16/2014] [Accepted: 05/25/2014] [Indexed: 01/05/2023]
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132
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Knapp O, Maier E, Waltenberger E, Mazuet C, Benz R, Popoff MR. Residues involved in the pore-forming activity of theClostridium perfringensiota toxin. Cell Microbiol 2014; 17:288-302. [DOI: 10.1111/cmi.12366] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 07/09/2014] [Accepted: 09/22/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Oliver Knapp
- Institut Pasteur, Bactéries anaérobies et Toxines; 28 rue du Dr Roux, F-75724 Paris Cedex 15 France
| | - Elke Maier
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine; University of Würzburg; Versbacher Str. 9 D-97078 Würzburg Germany
| | - Eva Waltenberger
- School of Engineering and Science; Jacobs University Bremen; Campusring 1 D-28759 Bremen Germany
| | - Christelle Mazuet
- Institut Pasteur, Bactéries anaérobies et Toxines; 28 rue du Dr Roux, F-75724 Paris Cedex 15 France
| | - Roland Benz
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine; University of Würzburg; Versbacher Str. 9 D-97078 Würzburg Germany
- School of Engineering and Science; Jacobs University Bremen; Campusring 1 D-28759 Bremen Germany
| | - Michel R. Popoff
- Institut Pasteur, Bactéries anaérobies et Toxines; 28 rue du Dr Roux, F-75724 Paris Cedex 15 France
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133
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Awad MM, Johanesen PA, Carter GP, Rose E, Lyras D. Clostridium difficile virulence factors: Insights into an anaerobic spore-forming pathogen. Gut Microbes 2014; 5:579-93. [PMID: 25483328 PMCID: PMC4615314 DOI: 10.4161/19490976.2014.969632] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The worldwide emergence of epidemic strains of Clostridium difficile linked to increased disease severity and mortality has resulted in greater research efforts toward determining the virulence factors and pathogenesis mechanisms used by this organism to cause disease. C. difficile is an opportunist pathogen that employs many factors to infect and damage the host, often with devastating consequences. This review will focus on the role of the 2 major virulence factors, toxin A (TcdA) and toxin B (TcdB), as well as the role of other putative virulence factors, such as binary toxin, in C. difficile-mediated infection. Consideration is given to the importance of spores in both the initiation of disease and disease recurrence and also to the role that surface proteins play in host interactions.
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Key Words
- AAD, antibiotic associated diarrhea
- C. difficile,Clostridium difficile
- CDI, C. difficile infection
- CDT, Clostridium difficile transferase
- CDTLoc, CDT locus
- CDTa, CDT enzymatic component
- CDTb, CDT binding/translocation component
- CST, Clostridium spiroforme toxin
- CWPs, cell wall protein
- Clostridium
- ECF, extracytoplasmic function
- HMW, high molecular weight
- LMW, low molecular weight
- LSR, lipolysis-stimulated lipoprotein receptor
- PCR, polymerase chain reaction
- PFGE, pulsed field gel electrophoresis
- PaLoc, pathogenicity locus
- REA, restriction endonuclease analysis
- S-layer, surface layer
- SLPs, S-layer proteins
- TcdA, toxin A
- TcdB, toxin B
- antibiotic
- colitis
- difficile
- infection
- nosocomial
- toxin
- virulence factor
- ι-toxin, iota toxin
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Affiliation(s)
- Milena M Awad
- Department of Microbiology; Monash University; Clayton, Victoria, Australia
| | | | - Glen P Carter
- Department of Microbiology; Monash University; Clayton, Victoria, Australia
| | - Edward Rose
- Department of Microbiology; Monash University; Clayton, Victoria, Australia
| | - Dena Lyras
- Department of Microbiology; Monash University; Clayton, Victoria, Australia,Correspondence to: Dena Lyras;
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134
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Isolation and Characterization of a New Clostridium difficile Ribotype During a Prospective Study in a Hospital in Italy. Curr Microbiol 2014; 70:151-3. [DOI: 10.1007/s00284-014-0697-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 08/06/2014] [Indexed: 10/24/2022]
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135
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Simon NC, Aktories K, Barbieri JT. Novel bacterial ADP-ribosylating toxins: structure and function. Nat Rev Microbiol 2014; 12:599-611. [PMID: 25023120 PMCID: PMC5846498 DOI: 10.1038/nrmicro3310] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacterial ADP-ribosyltransferase toxins (bARTTs) transfer ADP-ribose to eukaryotic proteins to promote bacterial pathogenesis. In this Review, we use prototype bARTTs, such as diphtheria toxin and pertussis toxin, as references for the characterization of several new bARTTs from human, insect and plant pathogens, which were recently identified by bioinformatic analyses. Several of these toxins, including cholix toxin (ChxA) from Vibrio cholerae, SpyA from Streptococcus pyogenes, HopU1 from Pseudomonas syringae and the Tcc toxins from Photorhabdus luminescens, ADP-ribosylate novel substrates and have unique organizations, which distinguish them from the reference toxins. The characterization of these toxins increases our appreciation of the range of structural and functional properties that are possessed by bARTTs and their roles in bacterial pathogenesis.
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Affiliation(s)
- Nathan C. Simon
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI, USA
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology; Albert-Ludwigs-University Freiburg; Freiburg, Germany
| | - Joseph T. Barbieri
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI, USA
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136
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Fair RJ, Tor Y. Antibiotics and bacterial resistance in the 21st century. PERSPECTIVES IN MEDICINAL CHEMISTRY 2014; 6:25-64. [PMID: 25232278 PMCID: PMC4159373 DOI: 10.4137/pmc.s14459] [Citation(s) in RCA: 854] [Impact Index Per Article: 85.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/24/2014] [Accepted: 06/24/2014] [Indexed: 12/11/2022]
Abstract
Dangerous, antibiotic resistant bacteria have been observed with increasing frequency over the past several decades. In this review the factors that have been linked to this phenomenon are addressed. Profiles of bacterial species that are deemed to be particularly concerning at the present time are illustrated. Factors including economic impact, intrinsic and acquired drug resistance, morbidity and mortality rates, and means of infection are taken into account. Synchronously with the waxing of bacterial resistance there has been waning antibiotic development. The approaches that scientists are employing in the pursuit of new antibacterial agents are briefly described. The standings of established antibiotic classes as well as potentially emerging classes are assessed with an emphasis on molecules that have been clinically approved or are in advanced stages of development. Historical perspectives, mechanisms of action and resistance, spectrum of activity, and preeminent members of each class are discussed.
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Affiliation(s)
- Richard J Fair
- Department for Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Berlin, Germany
| | - Yitzhak Tor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
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137
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Gurnev PA, Nestorovich EM. Channel-forming bacterial toxins in biosensing and macromolecule delivery. Toxins (Basel) 2014; 6:2483-540. [PMID: 25153255 PMCID: PMC4147595 DOI: 10.3390/toxins6082483] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/08/2014] [Accepted: 08/08/2014] [Indexed: 12/19/2022] Open
Abstract
To intoxicate cells, pore-forming bacterial toxins are evolved to allow for the transmembrane traffic of different substrates, ranging from small inorganic ions to cell-specific polypeptides. Recent developments in single-channel electrical recordings, X-ray crystallography, protein engineering, and computational methods have generated a large body of knowledge about the basic principles of channel-mediated molecular transport. These discoveries provide a robust framework for expansion of the described principles and methods toward use of biological nanopores in the growing field of nanobiotechnology. This article, written for a special volume on "Intracellular Traffic and Transport of Bacterial Protein Toxins", reviews the current state of applications of pore-forming bacterial toxins in small- and macromolecule-sensing, targeted cancer therapy, and drug delivery. We discuss the electrophysiological studies that explore molecular details of channel-facilitated protein and polymer transport across cellular membranes using both natural and foreign substrates. The review focuses on the structurally and functionally different bacterial toxins: gramicidin A of Bacillus brevis, α-hemolysin of Staphylococcus aureus, and binary toxin of Bacillus anthracis, which have found their "second life" in a variety of developing medical and technological applications.
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Affiliation(s)
- Philip A Gurnev
- Physics Department, University of Massachusetts, Amherst, MA 01003, USA.
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138
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Paenibacillus larvae chitin-degrading protein PlCBP49 is a key virulence factor in American Foulbrood of honey bees. PLoS Pathog 2014; 10:e1004284. [PMID: 25080221 PMCID: PMC4117609 DOI: 10.1371/journal.ppat.1004284] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 06/17/2014] [Indexed: 11/19/2022] Open
Abstract
Paenibacillus larvae, the etiological agent of the globally occurring epizootic American Foulbrood (AFB) of honey bees, causes intestinal infections in honey bee larvae which develop into systemic infections inevitably leading to larval death. Massive brood mortality might eventually lead to collapse of the entire colony. Molecular mechanisms of host-microbe interactions in this system and of differences in virulence between P. larvae genotypes are poorly understood. Recently, it was demonstrated that the degradation of the peritrophic matrix lining the midgut epithelium is a key step in pathogenesis of P. larvae infections. Here, we present the isolation and identification of PlCBP49, a modular, chitin-degrading protein of P. larvae and demonstrate that this enzyme is crucial for the degradation of the larval peritrophic matrix during infection. PlCBP49 contains a module belonging to the auxiliary activity 10 (AA10, formerly CBM33) family of lytic polysaccharide monooxygenases (LPMOs) which are able to degrade recalcitrant polysaccharides. Using chitin-affinity purified PlCBP49, we provide evidence that PlCBP49 degrades chitin via a metal ion-dependent, oxidative mechanism, as already described for members of the AA10 family. Using P. larvae mutants lacking PlCBP49 expression, we analyzed in vivo biological functions of PlCBP49. In the absence of PlCBP49 expression, peritrophic matrix degradation was markedly reduced and P. larvae virulence was nearly abolished. This indicated that PlCBP49 is a key virulence factor for the species P. larvae. The identification of the functional role of PlCBP49 in AFB pathogenesis broadens our understanding of this important family of chitin-binding and -degrading proteins, especially in those bacteria that can also act as entomopathogens.
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139
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Ernst K, Langer S, Kaiser E, Osseforth C, Michaelis J, Popoff MR, Schwan C, Aktories K, Kahlert V, Malesevic M, Schiene-Fischer C, Barth H. Cyclophilin-facilitated membrane translocation as pharmacological target to prevent intoxication of mammalian cells by binary clostridial actin ADP-ribosylated toxins. J Mol Biol 2014; 427:1224-38. [PMID: 25058685 DOI: 10.1016/j.jmb.2014.07.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/03/2014] [Accepted: 07/13/2014] [Indexed: 11/16/2022]
Abstract
Clostridium botulinum C2 toxin, Clostridium perfringens iota toxin and Clostridium difficile CDT belong to the family of binary actin ADP-ribosylating toxins and are composed of a binding/translocation component and a separate enzyme component. The enzyme components ADP-ribosylate G-actin in the cytosol of target cells resulting in depolymerization of F-actin, cell rounding and cell death. The binding/translocation components bind to their cell receptors and form complexes with the respective enzyme components. After receptor-mediated endocytosis, the binding/translocation components form pores in membranes of acidified endosomes and the enzyme components translocate through these pores into the cytosol. This step is facilitated by the host cell chaperone heat shock protein 90 and peptidyl-prolyl cis/trans isomerases including cyclophilin A. Here, we demonstrate that a large isoform of cyclophilin A, the multi-domain enzyme cyclophilin 40 (Cyp40), binds to the enzyme components C2I, Ia and CDTa in vitro. Isothermal titration calorimetry revealed a direct binding to C2I with a calculated affinity of 101 nM and to Ia with an affinity of 1.01 μM. Closer investigation for the prototypic C2I revealed that binding to Cyp40 did not depend on its ADP-ribosyltransferase activity but was stronger for unfolded C2I. The interaction of C2I with Cyp40 was also demonstrated in lysates from C2-treated cells by pull-down. Treatment of cells with a non-immunosuppressive cyclosporine A derivative, which still binds to and inhibits the peptidyl-prolyl cis/trans isomerase activity of cyclophilins, protected cells from intoxication with C2, iota and CDT toxins, offering an attractive approach for development of novel therapeutic strategies against binary actin ADP-ribosylating toxins.
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Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89081 Ulm, Germany
| | - Simon Langer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89081 Ulm, Germany
| | - Eva Kaiser
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89081 Ulm, Germany
| | | | - Jens Michaelis
- Institute of Biophysics, University of Ulm, 89081 Ulm, Germany
| | - Michel R Popoff
- Department of Anaerobic Bacteria, Pasteur Institute, 75724 Paris, France
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany
| | - Viktoria Kahlert
- Max Planck Research Unit for Enzymology of Protein Folding Halle, 06120 Halle (Saale), Germany
| | - Miroslav Malesevic
- Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Cordelia Schiene-Fischer
- Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89081 Ulm, Germany.
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140
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Roeder M, Nestorovich EM, Karginov VA, Schwan C, Aktories K, Barth H. Tailored cyclodextrin pore blocker protects mammalian cells from clostridium difficile binary toxin CDT. Toxins (Basel) 2014; 6:2097-114. [PMID: 25029374 PMCID: PMC4113744 DOI: 10.3390/toxins6072097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 06/16/2014] [Accepted: 06/27/2014] [Indexed: 12/11/2022] Open
Abstract
Some Clostridium difficile strains produce, in addition to toxins A and B, the binary toxin Clostridium difficile transferase (CDT), which ADP-ribosylates actin and may contribute to the hypervirulence of these strains. The separate binding and translocation component CDTb mediates transport of the enzyme component CDTa into mammalian target cells. CDTb binds to its receptor on the cell surface, CDTa assembles and CDTb/CDTa complexes are internalised. In acidic endosomes, CDTb mediates the delivery of CDTa into the cytosol, most likely by forming a translocation pore in endosomal membranes. We demonstrate that a seven-fold symmetrical positively charged β-cyclodextrin derivative, per-6-S-(3-aminomethyl)benzylthio-β-cyclodextrin, which was developed earlier as a potent inhibitor of the translocation pores of related binary toxins of Bacillus anthracis, Clostridium botulinum and Clostridium perfringens, protects cells from intoxication with CDT. The pore blocker did not interfere with the CDTa-catalyzed ADP-ribosylation of actin or toxin binding to Vero cells but inhibited the pH-dependent membrane translocation of CDTa into the cytosol. In conclusion, the cationic β-cyclodextrin could serve as the lead compound in a development of novel pharmacological strategies against the CDT-producing strains of C. difficile.
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Affiliation(s)
- Maurice Roeder
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | | | - Vladimir A Karginov
- Innovative Biologics, Inc., 13455 Sunrise Valley Dr., Suite 200, Herndon, VA 20171, USA.
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany.
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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141
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Förstner P, Bayer F, Kalu N, Felsen S, Förtsch C, Aloufi A, Ng DYW, Weil T, Nestorovich EM, Barth H. Cationic PAMAM dendrimers as pore-blocking binary toxin inhibitors. Biomacromolecules 2014; 15:2461-74. [PMID: 24954629 PMCID: PMC4215879 DOI: 10.1021/bm500328v] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dendrimers are unique highly branched macromolecules with numerous groundbreaking biomedical applications under development. Here we identified poly(amido amine) (PAMAM) dendrimers as novel blockers for the pore-forming B components of the binary anthrax toxin (PA63) and Clostridium botulinum C2 toxin (C2IIa). These pores are essential for delivery of the enzymatic A components of the internalized toxins from endosomes into the cytosol of target cells. We demonstrate that at low μM concentrations cationic PAMAM dendrimers block PA63 and C2IIa to inhibit channel-mediated transport of the A components, thereby protecting HeLa and Vero cells from intoxication. By channel reconstitution and high-resolution current recording, we show that the PAMAM dendrimers obstruct transmembrane PA63 and C2IIa pores in planar lipid bilayers at nM concentrations. These findings suggest a new potential role for the PAMAM dendrimers as effective polyvalent channel-blocking inhibitors, which can protect human target cells from intoxication with binary toxins from pathogenic bacteria.
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Affiliation(s)
- Philip Förstner
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center , D-89081 Ulm, Germany
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142
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Popoff MR. Bacterial factors exploit eukaryotic Rho GTPase signaling cascades to promote invasion and proliferation within their host. Small GTPases 2014; 5:28209. [PMID: 25203748 DOI: 10.4161/sgtp.28209] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Actin cytoskeleton is a main target of many bacterial pathogens. Among the multiple regulation steps of the actin cytoskeleton, bacterial factors interact preferentially with RhoGTPases. Pathogens secrete either toxins which diffuse in the surrounding environment, or directly inject virulence factors into target cells. Bacterial toxins, which interfere with RhoGTPases, and to some extent with RasGTPases, catalyze a covalent modification (ADPribosylation, glucosylation, deamidation, adenylation, proteolysis) blocking these molecules in their active or inactive state, resulting in alteration of epithelial and/or endothelial barriers, which contributes to dissemination of bacteria in the host. Injected bacterial virulence factors preferentially manipulate the RhoGTPase signaling cascade by mimicry of eukaryotic regulatory proteins leading to local actin cytoskeleton rearrangement, which mediates bacterial entry into host cells or in contrast escape to phagocytosis and immune defense. Invasive bacteria can also manipulate RhoGTPase signaling through recognition and stimulation of cell surface receptor(s). Changes in RhoGTPase activation state is sensed by the innate immunity pathways and allows the host cell to adapt an appropriate defense response.
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Affiliation(s)
- Michel R Popoff
- Unité des Bactéries anaérobies et Toxines; Institut Pasteur; Paris, France
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143
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Intracellular trafficking of Clostridium botulinum C2 toxin. Toxicon 2014; 82:76-82. [DOI: 10.1016/j.toxicon.2014.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/23/2014] [Accepted: 02/11/2014] [Indexed: 11/23/2022]
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144
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BEC, a novel enterotoxin of Clostridium perfringens found in human clinical isolates from acute gastroenteritis outbreaks. Infect Immun 2014; 82:2390-9. [PMID: 24664508 DOI: 10.1128/iai.01759-14] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Clostridium perfringens is a causative agent of food-borne gastroenteritis for which C. perfringens enterotoxin (CPE) has been considered an essential factor. Recently, we experienced two outbreaks of food-borne gastroenteritis in which non-CPE producers of C. perfringens were strongly suspected to be the cause. Here, we report a novel enterotoxin produced by C. perfringens isolates, BEC (binary enterotoxin of C. perfringens). Culture supernatants of the C. perfringens strains showed fluid-accumulating activity in rabbit ileal loop and suckling mouse assays. Purification of the enterotoxic substance in the supernatants and high-throughput sequencing of genomic DNA of the strains revealed BEC, composed of BECa and BECb. BECa and BECb displayed limited amino acid sequence similarity to other binary toxin family members, such as the C. perfringens iota toxin. The becAB genes were located on 54.5-kb pCP13-like plasmids. Recombinant BECb (rBECb) alone had fluid-accumulating activity in the suckling mouse assay. Although rBECa alone did not show enterotoxic activity, rBECa enhanced the enterotoxicity of rBECb when simultaneously administered in suckling mice. The entertoxicity of the mutant in which the becB gene was disrupted was dramatically decreased compared to that of the parental strain. rBECa showed an ADP-ribosylating activity on purified actin. Although we have not directly evaluated whether BECb delivers BECa into cells, rounding of Vero cells occurred only when cells were treated with both rBECa and rBECb. These results suggest that BEC is a novel enterotoxin of C. perfringens distinct from CPE, and that BEC-producing C. perfringens strains can be causative agents of acute gastroenteritis in humans. Additionally, the presence of becAB on nearly identical plasmids in distinct lineages of C. perfringens isolates suggests the involvement of horizontal gene transfer in the acquisition of the toxin genes.
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145
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Leuzzi R, Adamo R, Scarselli M. Vaccines against Clostridium difficile. Hum Vaccin Immunother 2014; 10:1466-77. [PMID: 24637887 DOI: 10.4161/hv.28428] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Clostridium difficile infection (CDI) is recognized as a major cause of nosocomial diseases ranging from antibiotic related diarrhea to fulminant colitis. Emergence during the last 2 decades of C. difficile strains associated with high incidence, severity and lethal outcomes has increased the challenges for CDI treatment. A limited number of drugs have proven to be effective against CDI and concerns about antibiotic resistance as well as recurring disease solicited the search for novel therapeutic strategies. Active vaccination provides the attractive opportunity to prevent CDI, and intense research in recent years led to development of experimental vaccines, 3 of which are currently under clinical evaluation. This review summarizes recent achievements and remaining challenges in the field of C. difficile vaccines, and discusses future perspectives in view of newly-identified candidate antigens.
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146
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Development and optimization of a high-throughput assay to measure neutralizing antibodies against Clostridium difficile binary toxin. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:689-97. [PMID: 24623624 DOI: 10.1128/cvi.00038-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Clostridium difficile strains producing binary toxin, in addition to toxin A (TcdA) and toxin B (TcdB), have been associated with more severe disease and increased recurrence of C. difficile infection in recent outbreaks. Binary toxin comprises two subunits (CDTa and CDTb) and catalyzes the ADP-ribosylation of globular actin (G-actin), which leads to the depolymerization of filamentous actin (F-actin) filaments. A robust assay is highly desirable for detecting the cytotoxic effect of the toxin and the presence of neutralizing antibodies in animal and human sera to evaluate vaccine efficacy. We describe here the optimization, using design-of-experiment (DOE) methodology, of a high-throughput assay to measure the toxin potency and neutralizing antibodies (NAb) against binary toxin. Vero cells were chosen from a panel of cells screened for sensitivity and specificity. We have successfully optimized the CDTa-to-CDTb molar ratio, toxin concentration, cell-seeding density, and sera-toxin preincubation time in the NAb assay using DOE methodology. This assay is robust, produces linear results across serial dilutions of hyperimmune serum, and can be used to quantify neutralizing antibodies in sera from hamsters and monkeys immunized with C. difficile binary toxin-containing vaccines. The assay will be useful for C. difficile diagnosis, for epidemiology studies, and for selecting and optimizing vaccine candidates.
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147
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Djukic M, Brzuszkiewicz E, Fünfhaus A, Voss J, Gollnow K, Poppinga L, Liesegang H, Garcia-Gonzalez E, Genersch E, Daniel R. How to kill the honey bee larva: genomic potential and virulence mechanisms of Paenibacillus larvae. PLoS One 2014; 9:e90914. [PMID: 24599066 PMCID: PMC3944939 DOI: 10.1371/journal.pone.0090914] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 02/05/2014] [Indexed: 12/20/2022] Open
Abstract
Paenibacillus larvae, a Gram positive bacterial pathogen, causes American Foulbrood (AFB), which is the most serious infectious disease of honey bees. In order to investigate the genomic potential of P. larvae, two strains belonging to two different genotypes were sequenced and used for comparative genome analysis. The complete genome sequence of P. larvae strain DSM 25430 (genotype ERIC II) consisted of 4,056,006 bp and harbored 3,928 predicted protein-encoding genes. The draft genome sequence of P. larvae strain DSM 25719 (genotype ERIC I) comprised 4,579,589 bp and contained 4,868 protein-encoding genes. Both strains harbored a 9.7 kb plasmid and encoded a large number of virulence-associated proteins such as toxins and collagenases. In addition, genes encoding large multimodular enzymes producing nonribosomally peptides or polyketides were identified. In the genome of strain DSM 25719 seven toxin associated loci were identified and analyzed. Five of them encoded putatively functional toxins. The genome of strain DSM 25430 harbored several toxin loci that showed similarity to corresponding loci in the genome of strain DSM 25719, but were non-functional due to point mutations or disruption by transposases. Although both strains cause AFB, significant differences between the genomes were observed including genome size, number and composition of transposases, insertion elements, predicted phage regions, and strain-specific island-like regions. Transposases, integrases and recombinases are important drivers for genome plasticity. A total of 390 and 273 mobile elements were found in strain DSM 25430 and strain DSM 25719, respectively. Comparative genomics of both strains revealed acquisition of virulence factors by horizontal gene transfer and provided insights into evolution and pathogenicity.
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Affiliation(s)
- Marvin Djukic
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Elzbieta Brzuszkiewicz
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Anne Fünfhaus
- Department for Molecular Microbiology and Bee Diseases, Institute for Bee Research, Hohen Neuendorf, Germany
| | - Jörn Voss
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Kathleen Gollnow
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Lena Poppinga
- Department for Molecular Microbiology and Bee Diseases, Institute for Bee Research, Hohen Neuendorf, Germany
| | - Heiko Liesegang
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
| | - Eva Garcia-Gonzalez
- Department for Molecular Microbiology and Bee Diseases, Institute for Bee Research, Hohen Neuendorf, Germany
| | - Elke Genersch
- Department for Molecular Microbiology and Bee Diseases, Institute for Bee Research, Hohen Neuendorf, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
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148
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TcdA1 of Photorhabdus luminescens: electrophysiological analysis of pore formation and effector binding. Biophys J 2014; 105:376-84. [PMID: 23870259 DOI: 10.1016/j.bpj.2013.06.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 11/23/2022] Open
Abstract
Tc toxins are widely distributed among different gram-negative and gram-positive bacteria, where they act as pathogenicity factors. The toxins are composed of different components that form oligomers for biological activity. Lipid bilayer experiments were performed with the TcdA1 component of the Tc toxin from Photorhabdus luminescens, which preferentially kills insects by actin polymerization. TcdA1 was able to increase the specific conductance of artificial lipid bilayer membranes by the formation of ion-permeable channels. The channels had on average a single-channel conductance of 125 pS in 150 mM KCl and were found to be cation selective. The single-channel conductance of the TcdA1-channels was only moderately dependent on the bulk aqueous KCl concentration, which indicated point-charge effects on the channel properties. Experiments to study the voltage dependence of the TcdA1 channel demonstrated that it is reconstituted in a fully oriented way when it is added to only one side of the lipid bilayer membrane. A combination of biologically active components (TccC3) and a possible chaperone (TcdB2) blocked the TcdA1-mediated conductance efficiently in a dose-dependent manner when they were added to the cis side of the membrane. The half-saturation constant for binding of TcdB2-TccC3 to TcdA1 is in the low nanomolar range.
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149
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Inhibitions of the translocation pore of Clostridium botulinum C2 toxin by tailored azolopyridinium salts protects human cells from intoxication. Toxicology 2014; 316:25-33. [DOI: 10.1016/j.tox.2013.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 12/13/2013] [Accepted: 12/22/2013] [Indexed: 11/19/2022]
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150
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Abstract
INTRODUCTION Present-day rational drug design approaches are based on exploiting unique features of the target biomolecules, small- or macromolecule drug candidates and physical forces that govern their interactions. The 2013 Nobel Prize in chemistry awarded 'for the development of multiscale models for complex chemical systems' once again demonstrated the importance of the tailored drug discovery that reduces the role of the trial-and-error approach to a minimum. The intentional dissemination of Bacillus anthracis spores in 2001 via the so-called anthrax letters has led to increased efforts, politically and scientifically, to develop medical countermeasures that will protect people from the threat of anthrax bioterrorism. AREAS COVERED This article provides an overview of the recent rational drug design approaches for discovering inhibitors of anthrax toxin. The review also directs the readers to the vast literature on the recognized advances and future possibilities in the field. EXPERT OPINION Existing options to combat anthrax toxin lethality are limited. With the only anthrax toxin inhibiting therapy (protective antigen-targeting with a monoclonal antibody, raxibacumab) approved to treat inhalational anthrax, the situation, in our view, is still insecure. Further, the FDA's animal rule for drug approval, which clears compounds without validated efficacy studies on humans, creates a high level of uncertainty, especially when a well-characterized animal model does not exist. Better identification and validation of anthrax toxin therapeutic targets at the molecular level as well as elucidation of the parameters determining the corresponding therapeutic windows are still necessary for more effective therapeutic options.
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Affiliation(s)
- Ekaterina M Nestorovich
- The Catholic University of America, Department of Biology , Washington, DC , USA +1 202 319 6723 ;
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