1
|
Liu W, Nestorovich EM. Anthrax toxin channel: What we know based on over 30 years of research. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183715. [PMID: 34332985 DOI: 10.1016/j.bbamem.2021.183715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Protective antigen channel is the central component of the deadly anthrax exotoxin responsible for binding and delivery of the toxin's enzymatic lethal and edema factor components into the cytosol. The channel, which is more than three times longer than the lipid bilayer membrane thickness and has a 6-Å limiting diameter, is believed to provide a sophisticated unfoldase and translocase machinery for the foreign protein transport into the host cell cytosol. The tripartite toxin can be reengineered, one component at a time or collectively, to adapt it for the targeted cancer therapeutic treatments. In this review, we focus on the biophysical studies of the protective antigen channel-forming activity, small ion transport properties, enzymatic factor translocation, and blockage comparing it with the related clostridial binary toxin channels. We address issues linked to the anthrax toxin channel structural dynamics and lipid dependence, which are yet to become generally recognized as parts of the toxin translocation machinery.
Collapse
Affiliation(s)
- Wenxing Liu
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA.
| |
Collapse
|
2
|
Ernst K, Landenberger M, Nieland J, Nørgaard K, Frick M, Fois G, Benz R, Barth H. Characterization and Pharmacological Inhibition of the Pore-Forming Clostridioides difficile CDTb Toxin. Toxins (Basel) 2021; 13:toxins13060390. [PMID: 34071730 PMCID: PMC8226936 DOI: 10.3390/toxins13060390] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 12/18/2022] Open
Abstract
The clinically highly relevant Clostridioides (C.) difficile releases several AB-type toxins that cause diseases such as diarrhea and pseudomembranous colitis. In addition to the main virulence factors Rho/Ras-glycosylating toxins TcdA and TcdB, hypervirulent strains produce the binary AB-type toxin CDT. CDT consists of two separate proteins. The binding/translocation B-component CDTb facilitates uptake and translocation of the enzyme A-component CDTa to the cytosol of cells. Here, CDTa ADP-ribosylates G-actin, resulting in depolymerization of the actin cytoskeleton. We previously showed that CDTb exhibits cytotoxicity in the absence of CDTa, which is most likely due to pore formation in the cytoplasmic membrane. Here, we further investigated this cytotoxic effect and showed that CDTb impairs CaCo-2 cell viability and leads to redistribution of F-actin without affecting tubulin structures. CDTb was detected at the cytoplasmic membrane in addition to its endosomal localization if CDTb was applied alone. Chloroquine and several of its derivatives, which were previously identified as toxin pore blockers, inhibited intoxication of Vero, HCT116, and CaCo-2 cells by CDTb and CDTb pores in vitro. These results further strengthen pore formation by CDTb in the cytoplasmic membrane as the underlying cytotoxic mechanism and identify pharmacological pore blockers as potent inhibitors of cytotoxicity induced by CDTb and CDTa plus CDTb.
Collapse
Affiliation(s)
- Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
- Correspondence: (K.E.); (H.B.)
| | - Marc Landenberger
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
| | - Julian Nieland
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
| | - Katharina Nørgaard
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
| | - Manfred Frick
- Institute of General Physiology, Ulm University, 89081 Ulm, Germany; (M.F.); (G.F.)
| | - Giorgio Fois
- Institute of General Physiology, Ulm University, 89081 Ulm, Germany; (M.F.); (G.F.)
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs-University Bremen, 28759 Bremen, Germany;
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (M.L.); (J.N.); (K.N.)
- Correspondence: (K.E.); (H.B.)
| |
Collapse
|
3
|
Receptor-Binding and Uptake of Binary Actin-ADP-Ribosylating Toxins. Curr Top Microbiol Immunol 2019; 406:119-133. [PMID: 27817176 DOI: 10.1007/82_2016_46] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Binary actin-ADP-ribosylating toxins (e.g., Clostridium botulinum C2 toxin or Clostridium perfringens iota toxin ) consist of two separate proteins: An ADP-ribosyltransferase, which modifies actin thereby inhibiting actin polymerization, and a binding component that forms heptamers after proteolytic activation. While C2 toxin interacts with carbohydrate structures on host cells, the group of iota-like toxins binds to lipolysis-stimulated lipoprotein receptor (LSR). Here, we review LSR and discuss the role and function of LSR in interaction of iota-like toxins with host cells.
Collapse
|
4
|
Toxin Transport by A-B Type of Toxins in Eukaryotic Target Cells and Its Inhibition by Positively Charged Heterocyclic Molecules. Curr Top Microbiol Immunol 2017; 406:229-256. [DOI: 10.1007/82_2017_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
5
|
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]
|
6
|
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.
Collapse
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
| | | |
Collapse
|
7
|
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.
Collapse
|
8
|
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
| |
Collapse
|
9
|
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.
Collapse
Affiliation(s)
- Philip A Gurnev
- Physics Department, University of Massachusetts, Amherst, MA 01003, USA.
| | | |
Collapse
|
10
|
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.
Collapse
Affiliation(s)
- Philip Förstner
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center , D-89081 Ulm, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Popoff MR, Bouvet P. Genetic characteristics of toxigenic Clostridia and toxin gene evolution. Toxicon 2013; 75:63-89. [DOI: 10.1016/j.toxicon.2013.05.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/30/2013] [Accepted: 05/08/2013] [Indexed: 12/14/2022]
|
12
|
Beitzinger C, Bronnhuber A, Duscha K, Riedl Z, Huber-Lang M, Benz R, Hajós G, Barth H. Designed azolopyridinium salts block protective antigen pores in vitro and protect cells from anthrax toxin. PLoS One 2013; 8:e66099. [PMID: 23840407 PMCID: PMC3688708 DOI: 10.1371/journal.pone.0066099] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/02/2013] [Indexed: 11/28/2022] Open
Abstract
Background Several intracellular acting bacterial protein toxins of the AB-type, which are known to enter cells by endocytosis, are shown to produce channels. This holds true for protective antigen (PA), the binding component of the tripartite anthrax-toxin of Bacillus anthracis. Evidence has been presented that translocation of the enzymatic components of anthrax-toxin across the endosomal membrane of target cells and channel formation by the heptameric/octameric PA63 binding/translocation component are related phenomena. Chloroquine and some 4-aminoquinolones, known as potent drugs against Plasmodium falciparium infection of humans, block efficiently the PA63-channel in a dose dependent way. Methodology/Principal Findings Here we demonstrate that related positively charged heterocyclic azolopyridinium salts block the PA63-channel in the µM range, when both, inhibitor and PA63 are added to the same side of the membrane, the cis-side, which corresponds to the lumen of acidified endosomal vesicles of target cells. Noise-analysis allowed the study of the kinetics of the plug formation by the heterocycles. In vivo experiments using J774A.1 macrophages demonstrated that the inhibitors of PA63-channel function also efficiently block intoxication of the cells by the combination lethal factor and PA63 in the same concentration range as they block the channels in vitro. Conclusions/Significance These results strongly argue in favor of a transport of lethal factor through the PA63-channel and suggest that the heterocycles used in this study could represent attractive candidates for development of novel therapeutic strategies against anthrax.
Collapse
Affiliation(s)
- Christoph Beitzinger
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Anika Bronnhuber
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Kerstin Duscha
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Zsuzsanna Riedl
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Markus Huber-Lang
- Institute of Traumatology, Hand- and Reconstructive Surgery, University of Ulm Medical Center, Ulm, Germany
| | - Roland Benz
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
- School of Engineering and Science, Jacobs University Bremen, Bremen, Germany
- * E-mail: (RB); (HB)
| | - György Hajós
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
- * E-mail: (RB); (HB)
| |
Collapse
|
13
|
A human/murine chimeric fab antibody neutralizes anthrax lethal toxin in vitro. Clin Dev Immunol 2013; 2013:475809. [PMID: 23861692 PMCID: PMC3687597 DOI: 10.1155/2013/475809] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 05/12/2013] [Accepted: 05/13/2013] [Indexed: 12/21/2022]
Abstract
Human anthrax infection caused by exposure to Bacillus anthracis cannot always be treated by antibiotics. This is mostly because of the effect of the remaining anthrax toxin in the body. Lethal factor (LF) is a component of lethal toxin (LeTx), which is the major virulence of anthrax toxin. A murine IgG monoclonal antibody (mAb) against LF with blocking activity (coded LF8) was produced in a previous study. In this report, a human/murine chimeric Fab mAb (coded LF8-Fab) was developed from LF8 by inserting murine variable regions into human constant regions using antibody engineering to reduce the incompatibility of the murine antibody for human use. The LF8-Fab expressed in Escherichia coli could specifically identify LF with an affinity of 3.46 × 107 L/mol and could neutralize LeTx with an EC50 of 85 μg/mL. Even after LeTx challenge at various time points, the LF8-Fab demonstrated protection of J774A.1 cells in vitro. The results suggest that the LF8-Fab might be further characterized and potentially be used for clinical applications against anthrax infection.
Collapse
|
14
|
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, U.S.A
| |
Collapse
|
15
|
Beitzinger C, Stefani C, Kronhardt A, Rolando M, Flatau G, Lemichez E, Benz R. Role of N-terminal His6-Tags in binding and efficient translocation of polypeptides into cells using anthrax protective antigen (PA). PLoS One 2012; 7:e46964. [PMID: 23056543 PMCID: PMC3466187 DOI: 10.1371/journal.pone.0046964] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 09/06/2012] [Indexed: 12/21/2022] Open
Abstract
It is of interest to define bacterial toxin biochemical properties to use them as molecular-syringe devices in order to deliver enzymatic activities into host cells. Binary toxins of the AB7/8-type are among the most potent and specialized bacterial protein toxins. The B subunits oligomerize to form a pore that binds with high affinity host cell receptors and the enzymatic A subunit. This allows the endocytosis of the complex and subsequent injection of the A subunit into the cytosol of the host cells. Here we report that the addition of an N-terminal His6-tag to different proteins increased their binding affinity to the protective antigen (PA) PA63-channels, irrespective if they are related (C2I) or unrelated (gpJ, EDIN) to the AB7/8-family of toxins. His6-EDIN exhibited voltage-dependent increase of the stability constant for binding by a factor of about 25 when the trans-side corresponding to the cell interior was set to −70 mV. Surprisingly, the C. botulinum toxin C2II-channel did not share this feature of PA63. Cell-based experiments demonstrated that addition of an N-terminal His6-tag promoted also intoxication of endothelial cells by C2I or EDIN via PA63. Our results revealed that addition of His6-tags to several factors increase their binding properties to PA63 and enhance the property to intoxicate cells.
Collapse
Affiliation(s)
- Christoph Beitzinger
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Caroline Stefani
- Toxines microbiennes dans la relation hôte-pathogènes, C3M, U1065, Inserm, Nice, France
- UFR Médecine, IFR50, Université de Nice-Sophia Antipolis, Nice, France
| | - Angelika Kronhardt
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Monica Rolando
- Toxines microbiennes dans la relation hôte-pathogènes, C3M, U1065, Inserm, Nice, France
- UFR Médecine, IFR50, Université de Nice-Sophia Antipolis, Nice, France
| | - Gilles Flatau
- Toxines microbiennes dans la relation hôte-pathogènes, C3M, U1065, Inserm, Nice, France
| | - Emmanuel Lemichez
- Toxines microbiennes dans la relation hôte-pathogènes, C3M, U1065, Inserm, Nice, France
- UFR Médecine, IFR50, Université de Nice-Sophia Antipolis, Nice, France
- * E-mail: (EL); (RB)
| | - Roland Benz
- Rudolf-Virchow-Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
- School of Engineering and Science, Jacobs University Bremen, Bremen, Germany
- * E-mail: (EL); (RB)
| |
Collapse
|
16
|
Stiles BG, Wigelsworth DJ, Popoff MR, Barth H. Clostridial binary toxins: iota and C2 family portraits. Front Cell Infect Microbiol 2011; 1:11. [PMID: 22919577 PMCID: PMC3417380 DOI: 10.3389/fcimb.2011.00011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 11/10/2011] [Indexed: 02/04/2023] Open
Abstract
There are many pathogenic Clostridium species with diverse virulence factors that include protein toxins. Some of these bacteria, such as C. botulinum, C. difficile, C. perfringens, and C. spiroforme, cause enteric problems in animals as well as humans. These often fatal diseases can partly be attributed to binary protein toxins that follow a classic AB paradigm. Within a targeted cell, all clostridial binary toxins destroy filamentous actin via mono-ADP-ribosylation of globular actin by the A component. However, much less is known about B component binding to cell-surface receptors. These toxins share sequence homology amongst themselves and with those produced by another Gram-positive, spore-forming bacterium also commonly associated with soil and disease: Bacillus anthracis. This review focuses upon the iota and C2 families of clostridial binary toxins and includes: (1) basics of the bacterial source; (2) toxin biochemistry; (3) sophisticated cellular uptake machinery; and (4) host–cell responses following toxin-mediated disruption of the cytoskeleton. In summary, these protein toxins aid diverse enteric species within the genus Clostridium.
Collapse
Affiliation(s)
- Bradley G Stiles
- Biology Department, Wilson College, Chambersburg, PA, USA; Integrated Toxicology Division, Medical Research Institute of Infectious Diseases, Frederick, MD, USA.
| | | | | | | |
Collapse
|