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Chakravorty A, Awad MM, Cheung JK, Hiscox TJ, Lyras D, Rood JI. The pore-forming α-toxin from clostridium septicum activates the MAPK pathway in a Ras-c-Raf-dependent and independent manner. Toxins (Basel) 2015; 7:516-34. [PMID: 25675415 PMCID: PMC4344638 DOI: 10.3390/toxins7020516] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/02/2015] [Indexed: 12/13/2022] Open
Abstract
Clostridium septicum is the causative agent of atraumatic gas gangrene, with α-toxin, an extracellular pore-forming toxin, essential for disease. How C. septicum modulates the host’s innate immune response is poorly defined, although α-toxin-intoxicated muscle cells undergo cellular oncosis, characterised by mitochondrial dysfunction and release of reactive oxygen species. Nonetheless, the signalling events that occur prior to the initiation of oncosis are poorly characterised. Our aims were to characterise the ability of α-toxin to activate the host mitogen activated protein kinase (MAPK) signalling pathway both in vitro and in vivo. Treatment of Vero cells with purified α-toxin activated the extracellular-signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 arms of the MAPK pathway and stimulated the release of TNF-α in a dose-dependent manner. Studies using inhibitors of all three MAPK components suggested that activation of ERK occurred in a Ras-c-Raf dependent manner, whereas activation of JNK and p38 occurred by a Ras-independent mechanism. Toxin-mediated activation was dependent on efficient receptor binding and pore formation and on an influx of extracellular calcium ions. In the mouse myonecrosis model we showed that the MAPK pathway was activated in tissues of infected mice, implying that it has an important role in the disease process.
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Affiliation(s)
- Anjana Chakravorty
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
| | - Milena M Awad
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
| | - Jackie K Cheung
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
| | - Thomas J Hiscox
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
| | - Dena Lyras
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
| | - Julian I Rood
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
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2
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Wuethrich I, Peeters JGC, Blom AEM, Theile CS, Li Z, Spooner E, Ploegh HL, Guimaraes CP. Site-specific chemoenzymatic labeling of aerolysin enables the identification of new aerolysin receptors. PLoS One 2014; 9:e109883. [PMID: 25275512 PMCID: PMC4183550 DOI: 10.1371/journal.pone.0109883] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 09/04/2014] [Indexed: 11/29/2022] Open
Abstract
Aerolysin is a secreted bacterial toxin that perforates the plasma membrane of a target cell with lethal consequences. Previously explored native and epitope-tagged forms of the toxin do not allow site-specific modification of the mature toxin with a probe of choice. We explore sortase-mediated transpeptidation reactions (sortagging) to install fluorophores and biotin at three distinct sites in aerolysin, without impairing binding of the toxin to the cell membrane and with minimal impact on toxicity. Using a version of aerolysin labeled with different fluorophores at two distinct sites we followed the fate of the C-terminal peptide independently from the N-terminal part of the toxin, and show its loss in the course of intoxication. Making use of the biotinylated version of aerolysin, we identify mesothelin, urokinase plasminogen activator surface receptor (uPAR, CD87), glypican-1, and CD59 glycoprotein as aerolysin receptors, all predicted or known to be modified with a glycosylphosphatidylinositol anchor. The sortase-mediated reactions reported here can be readily extended to other pore forming proteins.
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Affiliation(s)
- Irene Wuethrich
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Janneke G. C. Peeters
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Annet E. M. Blom
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Christopher S. Theile
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Zeyang Li
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Eric Spooner
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Hidde L. Ploegh
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
| | - Carla P. Guimaraes
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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3
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Knapp O, Maier E, Mkaddem SB, Benz R, Bens M, Chenal A, Geny B, Vandewalle A, Popoff MR. Clostridium septicum alpha-toxin forms pores and induces rapid cell necrosis. Toxicon 2009; 55:61-72. [PMID: 19632260 DOI: 10.1016/j.toxicon.2009.06.037] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/25/2009] [Accepted: 06/29/2009] [Indexed: 11/25/2022]
Abstract
Alpha-toxin is the unique lethal virulent factor produced by Clostridium septicum, which causes traumatic or non-traumatic gas gangrene and necrotizing enterocolitis in humans. Here, we analyzed channel formation of the recombinant septicum alpha-toxin and characterized its activity on living cells. Recombinant septicum alpha-toxin induces the formation of ion-permeable channels with a single-channel conductance of about 175pS in 0.1M KCl in lipid bilayer membranes, which is typical for a large diffusion pore. Septicum alpha-toxin channels remained mostly in the open configuration, displayed no lipid specificity, and exhibited slight anion selectivity. Septicum alpha-toxin caused a rapid decrease in the transepithelial electrical resistance of MDCK cell monolayers grown on filters, and induced a rapid cell necrosis in a variety of cell lines, characterized by cell permeabilization to propidium iodide without DNA fragmentation and activation of caspase-3. Septicum alpha-toxin also induced a rapid K(+) efflux and ATP depletion. Incubation of the cells in K(+)-enriched medium delayed cell death caused by septicum alpha-toxin or epsilon-toxin, another potent pore-forming toxin, suggesting that the rapid loss of intracellular K(+) represents an early signal of pore-forming toxins-mediated cell necrosis.
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Affiliation(s)
- Oliver Knapp
- Institut Pasteur, Bactéries anaérobies et Toxines, 28 rue du Dr Roux, F-75724 Paris cedex 15, France
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4
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Wu Q, Guo Z. Glycosylphosphatidylinositols are potential targets for the development of novel inhibitors for aerolysin-type of pore-forming bacterial toxins. Med Res Rev 2009; 30:258-69. [DOI: 10.1002/med.20167] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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5
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Osusky M, Teschke L, Wang X, Wong K, Buckley JT. A chimera of interleukin 2 and a binding variant of aerolysin is selectively toxic to cells displaying the interleukin 2 receptor. J Biol Chem 2007; 283:1572-1579. [PMID: 17981806 DOI: 10.1074/jbc.m706424200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aerolysin is a bacterial toxin that binds to glycosylphosphatidylinositol-anchored proteins (GPI-AP) on mammalian cells and oligomerizes, inserting into the target membranes and forming channels that cause cell death. We have made a variant of aerolysin, R336A, that has greatly reduced the ability to bind to GPI-AP, and as a result it is only very weakly active. Fusion of interleukin 2 (IL2) to the N terminus of R336A-aerolysin results in a hybrid that has little or no activity against cells that do not have an IL2 receptor because it cannot bind to the GPI-AP on the cells. Strikingly, the presence of the IL2 moiety allows this hybrid to bind to cells displaying high affinity IL2 receptors. Once bound, the hybrid molecules form insertion-competent oligomers. Cell death occurs at picomolar concentrations of the hybrid, whereas the same cells are insensitive to much higher concentrations of R336A-aerolysin lacking the IL2 domain. The targeted channel-forming hybrid protein may have important advantages as a therapeutic agent.
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Affiliation(s)
- Milan Osusky
- Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada
| | - Lisa Teschke
- Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada
| | - Xiaoying Wang
- Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada
| | - Kevin Wong
- Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada
| | - J Thomas Buckley
- Protox Therapeutics Incorporated, Vancouver, British Columbia V6C 3E8, Canada.
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6
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Singh R, Browning JL, Abi-Habib R, Wong K, Williams SA, Merchant R, Denmeade SR, Buckley TJ, Frankel AE. Recombinant prostate-specific antigen proaerolysin shows selective protease sensitivity and cell cytotoxicity. Anticancer Drugs 2007; 18:809-16. [PMID: 17581303 DOI: 10.1097/cad.0b013e3280bad82d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Native proaerolysin is a channel-forming bacterial protoxin that binds to cell-surface receptors and then is activated by furin or furin-like proteases. We genetically engineered proaerolysin by replacing the furin-cleavage sequence with a prostate-specific antigen-selective sequence. The recombinant modified proaerolysin was expressed and purified from Aeromonas salmonicida in good yields and purity. Recombinant modified proaerolysin had no furin sensitivity and markedly increased prostate-specific antigen sensitivity relative to wild-type proaerolysin. Human prostate cancer cells were significantly more sensitive to recombinant modified proaerolysin in the presence of active prostate-specific antigen when compared with the absence of prostate-specific antigen or the presence of potent prostate-specific antigen inhibitors. Most normal human cells with the exception of prostate and renal epithelial cells showed very low sensitivity to recombinant modified proaerolysin. Our results suggest that recombinant modified proaerolysin is a potent prostate-specific antigen-sensitive protoxin that deserves further development for regional therapy of benign and malignant prostate growths.
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Affiliation(s)
- Ravibhushan Singh
- Cancer Research Institute, Scott & White Memorial Hospital, 5701 South Airport Road, Temple, TX 76502, USA
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7
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Parker MW, Feil SC. Pore-forming protein toxins: from structure to function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2005; 88:91-142. [PMID: 15561302 DOI: 10.1016/j.pbiomolbio.2004.01.009] [Citation(s) in RCA: 339] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pore-forming protein toxins (PFTs) are one of Nature's most potent biological weapons. An essential feature of their toxicity is the remarkable property that PFTs can exist either in a stable water-soluble state or as an integral membrane pore. In order to convert from the water-soluble to the membrane state, the toxin must undergo large conformational changes. There are now more than a dozen PFTs for which crystal structures have been determined and the nature of the conformational changes they must undergo is beginning to be understood. Although they differ markedly in their primary, secondary, tertiary and quaternary structures, nearly all can be classified into one of two families based on the types of pores they are thought to form: alpha-PFTs or beta-PFTs. Recent work suggests a number of common features in the mechanism of membrane insertion may exist for each class.
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Affiliation(s)
- Michael W Parker
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065, Australia.
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8
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Torres VJ, Ivie SE, McClain MS, Cover TL. Functional properties of the p33 and p55 domains of the Helicobacter pylori vacuolating cytotoxin. J Biol Chem 2005; 280:21107-14. [PMID: 15817461 DOI: 10.1074/jbc.m501042200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Helicobacter pylori secretes an 88-kDa vacuolating cytotoxin (VacA) that may contribute to the pathogenesis of peptic ulcer disease and gastric cancer. VacA cytotoxic activity requires assembly of VacA monomers into oligomeric structures, formation of anion-selective membrane channels, and entry of VacA into host cells. In this study, we analyzed the functional properties of recombinant VacA fragments corresponding to two putative VacA domains (designated p33 and p55). Immunoprecipitation experiments indicated that these two domains can interact with each other to form protein complexes. In comparison to the individual VacA domains, a mixture of the p33 and p55 proteins exhibited markedly enhanced binding to the plasma membrane of mammalian cells. Furthermore, internalization of the VacA domains was detected when cells were incubated with the p33/p55 mixture but not when the p33 and p55 proteins were tested individually. Incubation of cells with the p33/p55 mixture resulted in cell vacuolation, whereas the individual domains lacked detectable cytotoxic activity. Interestingly, sequential addition of p55 followed by p33 resulted in VacA internalization and cell vacuolation, whereas sequential addition in the reverse order was ineffective. These results indicate that both the p33 and p55 domains contribute to the binding and internalization of VacA and that both domains are required for vacuolating cytotoxic activity. Reconstitution of toxin activity from two separate domains, as described here for VacA, has rarely been described for pore-forming bacterial toxins, which suggests that VacA is a pore-forming toxin with unique structural properties.
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Affiliation(s)
- Victor J Torres
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2605, USA
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9
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Shin DJ, Lee JJ, Choy HE, Hong Y. Generation and characterization of Clostridium septicum alpha toxin mutants and their use in diagnosing paroxysmal nocturnal hemoglobinuria. Biochem Biophys Res Commun 2004; 324:753-60. [PMID: 15474491 DOI: 10.1016/j.bbrc.2004.09.104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Indexed: 11/20/2022]
Abstract
Glycosylphosphatidylinositol (GPI) anchors various proteins to the membrane of eukaryotic cells. Paroxysmal nocturnal hemoglobinuria (PNH) is a hematopoietic stem cell disorder that is primarily due to the lack of GPI-anchored proteins on the surface of blood cells. To detect the GPI-deficient cells in PNH patients, we modified alpha toxin, a pore-forming toxin of the Gram-positive bacterium Clostridium septicum. We first showed that aerolysin, a homologous toxin from Aeromonas hydrophila, bound to both of Chinese hamster ovary cells deficient of N-glycan maturation as well as GPI biosynthesis at a significant level. However, alpha toxin bound to the mutant cells of N-glycosylation, but not to GPI-deficient cells. It suggested that alpha toxin could be used as a specific probe to differentiate only GPI-deficient cells. As a diagnostic probe, alpha toxin must be the least cytotoxic while maintaining its affinity for GPI. Thus, we constructed several mutants. Of these, the mutants carrying the Y155G or S189C/S238C substitutions bound to GPI as well as the wild-type toxin. These mutants also efficiently underwent proteolytic activation and aggregated into oligomers on the cell surface, which are events that precede the formation of a pore in the host cell membrane, leading to cell death. Nevertheless, these mutants almost completely failed to kill host cells. It was revealed that the substitutions affect the events that follow oligomerization. The S189C/S238C mutant toxin differentiated GPI-deficient granulocyte and PMN, but not red blood cells, of a PNH patient from GPI-positive cells at least as sensitively as the commercial monoclonal antibodies that recognize the CD59 or CD55 GPI proteins on blood cells. Thus, this modified bacterial toxin can be employed instead of costly monoclonal antibodies to diagnose PNH patients.
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Affiliation(s)
- Dong-Jun Shin
- Department of Microbiology, Genomic Research Center for Enteropathogenic Bacteria, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
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10
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Melton JA, Parker MW, Rossjohn J, Buckley JT, Tweten RK. The Identification and Structure of the Membrane-spanning Domain of the Clostridium septicum Alpha Toxin. J Biol Chem 2004; 279:14315-22. [PMID: 14715670 DOI: 10.1074/jbc.m313758200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alpha toxin (AT) is a pore-forming toxin produced by Clostridium septicum that belongs to the unique aerolysin-like family of pore-forming toxins. The location and structure of the transmembrane domains of these toxins have remained elusive. Using deletion mutagenesis, cysteine-scanning mutagenesis and multiple spectrofluorimetric methods a membrane-spanning amphipathic beta-hairpin of AT has been identified. Spectrofluorimetric analysis of cysteine-substituted residues modified with an environmentally sensitive fluorescent probe via the cysteine sulfydryl showed that the side chains of residues 203-232 alternated between the aqueous milieu and the membrane core when the AT oligomer was inserted into membranes, consistent with the formation of an amphipathic transmembrane beta-hairpin. AT derivatives that contained deletions that removed up to 90% of the beta-hairpin did not form a pore but were similar to native toxin in all other aspects of the mechanism. Furthermore, a mutant of AT that contained an engineered disulfide, predicted to restrict the movement of the beta-hairpin, functioned similarly to native toxin except that it did not form a pore unless the disulfide bond was reduced. Together these studies revealed the location and structure of the membrane-spanning domain of AT.
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Affiliation(s)
- Jody A Melton
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA
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11
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Hong Y, Ohishi K, Inoue N, Kang JY, Shime H, Horiguchi Y, van der Goot F, Sugimoto N, Kinoshita T. Requirement of N-glycan on GPI-anchored proteins for efficient binding of aerolysin but not Clostridium septicum alpha-toxin. EMBO J 2002; 21:5047-56. [PMID: 12356721 PMCID: PMC129030 DOI: 10.1093/emboj/cdf508] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Aerolysin of the Gram-negative bacterium Aeromonas hydrophila consists of small (SL) and large (LL) lobes. The alpha-toxin of Gram-positive Clostridium septicum has a single lobe homologous to LL. These toxins bind to glycosylphosphatidylinositol (GPI)-anchored proteins and generate pores in the cell's plasma membrane. We isolated CHO cells resistant to aerolysin, with the aim of obtaining GPI biosynthesis mutants. One mutant unexpectedly expressed GPI-anchored proteins, but nevertheless bound aerolysin poorly and was 10-fold less sensitive than wild-type cells. A cDNA of N-acetylglucosamine transferase I (GnTI) restored the binding of aerolysin to this mutant. Therefore, N-glycan is involved in the binding. Removal of mannoses by alpha-mannosidase II was important for the binding of aerolysin. In contrast, the alpha-toxin killed GnTI-deficient and wild-type CHO cells equally, indicating that its binding to GPI-anchored proteins is independent of N-glycan. Because SL bound to wild-type but not to GnTI-deficient cells, and because a hybrid toxin consisting of SL and the alpha-toxin killed wild-type cells 10-fold more efficiently than GnTI- deficient cells, SL with its binding site for N-glycan contributes to the high binding affinity of aerolysin.
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Affiliation(s)
| | | | - Norimitsu Inoue
- Departments of Immunoregulation and
Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Division of Advanced Medical Bacteriology, Department of Molecular and Applied Medicine, Medical School of Osaka University, Suita, Osaka, Japan and Department of Genetics and Microbiology, University of Geneva, Geneva, Switzerland Present address: Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Corresponding author e-mail:
| | | | - Hiroaki Shime
- Departments of Immunoregulation and
Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Division of Advanced Medical Bacteriology, Department of Molecular and Applied Medicine, Medical School of Osaka University, Suita, Osaka, Japan and Department of Genetics and Microbiology, University of Geneva, Geneva, Switzerland Present address: Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Corresponding author e-mail:
| | - Yasuhiko Horiguchi
- Departments of Immunoregulation and
Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Division of Advanced Medical Bacteriology, Department of Molecular and Applied Medicine, Medical School of Osaka University, Suita, Osaka, Japan and Department of Genetics and Microbiology, University of Geneva, Geneva, Switzerland Present address: Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Corresponding author e-mail:
| | - F.Gisou van der Goot
- Departments of Immunoregulation and
Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Division of Advanced Medical Bacteriology, Department of Molecular and Applied Medicine, Medical School of Osaka University, Suita, Osaka, Japan and Department of Genetics and Microbiology, University of Geneva, Geneva, Switzerland Present address: Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Corresponding author e-mail:
| | - Nakaba Sugimoto
- Departments of Immunoregulation and
Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Division of Advanced Medical Bacteriology, Department of Molecular and Applied Medicine, Medical School of Osaka University, Suita, Osaka, Japan and Department of Genetics and Microbiology, University of Geneva, Geneva, Switzerland Present address: Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Corresponding author e-mail:
| | - Taroh Kinoshita
- Departments of Immunoregulation and
Bacterial Toxinology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Division of Advanced Medical Bacteriology, Department of Molecular and Applied Medicine, Medical School of Osaka University, Suita, Osaka, Japan and Department of Genetics and Microbiology, University of Geneva, Geneva, Switzerland Present address: Department of Molecular Genetics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Corresponding author e-mail:
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Abstract
Like a variety of other pathogenic bacteria, Aeromonas hydrophila secretes a pore-forming toxin that contribute to its virulence. The last decade has not only increased our knowledge about the structure of this toxin, called aerolysin, but has also shed light on how it interacts with its target cell and how the cell reacts to this stress. Whereas pore-forming toxins are generally thought to lead to brutal death by osmotic lysis of the cell, based on what is observed for erythrocytes, recent studies have started to reveal far more complicated pathways leading to death of nucleated mammalian cells.
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Affiliation(s)
- M Fivaz
- Department of Biochemistry, Faculty of Sciences, University of Geneva, 30 quai E. Ansermet, 1211 Geneva 4, Switzerland
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13
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Dubail I, Autret N, Beretti JL, Kayal S, Berche P, Charbit A. Functional assembly of two membrane-binding domains in listeriolysin O, the cytolysin of Listeria monocytogenes. MICROBIOLOGY (READING, ENGLAND) 2001; 147:2679-2688. [PMID: 11577147 DOI: 10.1099/00221287-147-10-2679] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Listeriolysin O (LLO) is a major virulence factor secreted by the pathogenic Listeria monocytogenes and acts as pore-forming cytolysin. Based on sequence similarities between LLO and perfringolysin (PFO), the cytolysin from Clostridium perfringens of known crystallographic structure, two truncated LLO proteins were produced: LLO-d123, comprising the first three predicted domains, and LLO-d4, the last C-terminal domain. The two proteins were efficiently secreted into the culture supernatant of L. monocytogenes and were able to bind to cell membranes. Strikingly, when expressed simultaneously, the two secreted domains LLO-d123 and LLO-d4 reassembled into a haemolytically active form. Two in-frame linker insertions were generated in the hinge region between the d123 and d4 domains. In both cases, the insertion created a major cleavage site for proteolytic degradation and abolished cytolytic activity, which might suggest that the region connecting d123 and d4 participates in the interaction between the two portions of the monomer.
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Affiliation(s)
- Iharilalao Dubail
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France1
| | - Nicolas Autret
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France1
| | - Jean-Luc Beretti
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France1
| | - Samer Kayal
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France1
| | - Patrick Berche
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France1
| | - Alain Charbit
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France1
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14
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Burr SE, Diep DB, Buckley JT. Type II secretion by Aeromonas salmonicida: evidence for two periplasmic pools of proaerolysin. J Bacteriol 2001; 183:5956-63. [PMID: 11566995 PMCID: PMC99674 DOI: 10.1128/jb.183.20.5956-5963.2001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aeromonas salmonicida containing the cloned gene for proaerolysin secretes the protein via the type II secretory pathway. Here we show that altering a region near the beginning of aerA led to a dramatic increase in the amount of proaerolysin that was produced and that a large amount of the protein was cell associated. All of the cell-associated protein had crossed the cytoplasmic membrane, because the signal sequence had been removed, and all of it was accessible to processing by trypsin during osmotic shock. Enlargement of the periplasm was observed by electron microscopy in overproducing cells, likely caused by the osmotic effect of the very large concentrations of accumulated proaerolysin. Immunogold electron microscopy localized nearly all of the proaerolysin in the enlarged periplasm; however, only half of the protoxin was released from the cells by osmotic shocking. Cross-linking studies showed that this fraction contained normal dimeric proaerolysin but that proaerolysin in the fraction that was not shockable had not dimerized, although it appeared to be correctly folded. Both periplasmic fractions were secreted by the cells; however, the nonshockable fraction was secreted much more slowly than the shockable fraction. We estimated a rate for maximal secretion of proaerolysin from the bacteria that was much lower than the rates that have been estimated for inner membrane transit, which suggests that transit across the outer membrane is rate limiting and may account for the periplasmic accumulation of the protein. Finally, we show that overproduction of proaerolysin inhibited the release of the protease that is secreted by A. salmonicida.
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Affiliation(s)
- S E Burr
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
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Fivaz M, Abrami L, Tsitrin Y, van der Goot FG. Aerolysin from Aeromonas hydrophila and related toxins. Curr Top Microbiol Immunol 2001; 257:35-52. [PMID: 11417121 DOI: 10.1007/978-3-642-56508-3_3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- M Fivaz
- Department of Biochemistry, Faculty of Sciences, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
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Abrami L, Fivaz M, van der Goot FG. Surface dynamics of aerolysin on the plasma membrane of living cells. Int J Med Microbiol 2000; 290:363-7. [PMID: 11111912 DOI: 10.1016/s1438-4221(00)80042-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Aerolysin secreted by the human pathogen Aeromonas hydrophila belongs to a group of bacterial toxins that are hemolytic and form channels in biological membranes. The toxin is secreted as an inactive precursor proaerolysin that must be proteolytically processed at its C-terminus to become active. The toxin then polymerizes into a heptameric ring that is amphipathic and can insert into a lipid bilayer and form a pore. We have examined these various steps at the surface of target cells. The toxin binds to specific receptors. Various receptors have been identified, all of which are anchored to the plasma membrane via a glycosylphosphatidyl inositol (GPI)-anchored moiety. The GPI anchor confers to the protein that is linked to it two usual properties: (i) the protein has a higher lateral mobility in a phospholipid bilayer than its transmembrane counterpart, (ii) the protein has the capacity to transiently associate with cholesterol-glycosphingolipid-rich microdomains. We have shown that both these properties of GPI-anchored proteins are exploited by proaerolysin bound to its receptor. The high lateral mobility within the phosphoglyceride region of the plasma membrane favors the encounter of the protoxin with its converting enzyme furin. The ability to associate with microdomains on the other hand favors the oligomerization process presumably by concentrating the toxin locally.
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Affiliation(s)
- L Abrami
- Département de Biochimie, Université de Genève, Switzerland
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17
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Abstract
The past three years have shed light on how the pore-forming toxin aerolysin binds to its target cell and then hijacks cellular devices to promote its own polymerization and pore formation. This selective permeabilization of the plasma membrane has unexpected intracellular consequences that might explain the importance of aerolysin in Aeromonas pathogenicity.
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Affiliation(s)
- L Abrami
- Dept of Biochemistry, University of Geneva, 30 quai E. Ansermet, 1211 Geneva 4, Switzerland
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18
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Nomura T, Hamashima H, Okamoto K. Carboxy terminal region of haemolysin of Aeromonas sobria triggers dimerization. Microb Pathog 2000; 28:25-36. [PMID: 10623561 DOI: 10.1006/mpat.1999.0321] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Haemolysin of Aeromonas sobria is released into the culture supernatant in the form of prohaemolysin. Removal of a 42 amino acid peptide at the carboxy-terminal end converts prohaemolysin into mature haemolysin. As the role of the peptide removed from the mature haemolysin has not been studied, we mutated the haemolysin genes to delete several amino acid residues from the carboxy terminus, expressed the mutant genes in A. sobria and analysed the haemolysins produced. Deletion of more than three amino acid residues significantly reduced the efficiency of secretion of haemolysin into the culture supernatant. Mutant haemolysins with deletion of 10 amino acids were easily degraded in cells. Furthermore, cross-linking experiments indicated that the haemolysins dimerize in cells, and thus dimerized haemolysins are translocated across the outer membrane and appear in the culture supernatant. These results indicated that the carboxy-terminal end of prohaemolysin triggers dimerization of haemolysin in cells, resulting in the efficient secretion of haemolysin into the culture supernatant.
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Affiliation(s)
- T Nomura
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Yamashiro, Tokushima, 770-8514, Japan
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Swift S, Lynch MJ, Fish L, Kirke DF, Tomás JM, Stewart GS, Williams P. Quorum sensing-dependent regulation and blockade of exoprotease production in Aeromonas hydrophila. Infect Immun 1999; 67:5192-9. [PMID: 10496895 PMCID: PMC96870 DOI: 10.1128/iai.67.10.5192-5199.1999] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Aeromonas hydrophila, the ahyI gene encodes a protein responsible for the synthesis of the quorum sensing signal N-butanoyl-L-homoserine lactone (C4-HSL). Inactivation of the ahyI gene on the A. hydrophila chromosome abolishes C4-HSL production. The exoprotease activity of A. hydrophila consists of both serine protease and metalloprotease activities; in the ahyI-negative strain, both are substantially reduced but can be restored by the addition of exogenous C4-HSL. In contrast, mutation of the LuxR homolog AhyR results in the loss of both exoprotease activities, which cannot be restored by exogenous C4-HSL. Furthermore, a substantial reduction in the production of exoprotease by the ahyI+ parent strain is obtained by the addition of N-acylhomoserine lactone analogs that have acyl side chains of 10, 12, or 14 carbons. The inclusion of N-(3-oxododecanoyl)-L-homoserine lactone or N-(3-oxotetradecanoyl)-L-homoserine lactone at 10 microM in overnight cultures of A. hydrophila abolishes exoprotease production in azocasein assays and reduces the activity of all the exoprotease species seen in zymograms.
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Affiliation(s)
- S Swift
- Institute of Infections and Immunity, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, United Kingdom.
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MacKenzie CR, Hirama T, Buckley JT. Analysis of receptor binding by the channel-forming toxin aerolysin using surface plasmon resonance. J Biol Chem 1999; 274:22604-9. [PMID: 10428840 DOI: 10.1074/jbc.274.32.22604] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aerolysin is a channel-forming bacterial toxin that binds to glycosylphosphatidylinositol (GPI) anchors on host cell-surface structures. The nature of the receptors and the location of the receptor-binding sites on the toxin molecule were investigated using surface plasmon resonance. Aerolysin bound to the GPI-anchored proteins Thy-1, variant surface glycoprotein, and contactin with similar rate constants and affinities. Enzymatic removal of N-linked sugars from Thy-1 did not affect toxin binding, indicating that these sugars are not involved in the high affinity interaction with aerolysin. Aerolysin is a bilobal protein, and both lobes were shown to be required for optimal binding. The large lobe by itself bound Thy-1 with an affinity that was at least 10-fold weaker than that of the whole toxin, whereas the small lobe bound the GPI-anchored protein at least 1000-fold more weakly than the intact toxin. Mutation analyses provided further evidence that both lobes were involved in GPI anchor binding, with certain single amino acid substitutions in either domain leading to reductions in affinity of as much as 100-fold. A variant with single amino acid substitutions in both lobes of the protein was completely unable to bind the receptor. The membrane protein glycophorin, which is heavily glycosylated but not GPI-anchored, bound weakly to immobilized proaerolysin, suggesting that interactions with cell-surface carbohydrate structures other than GPI anchors may partially mediate toxin binding to host cells.
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Affiliation(s)
- C R MacKenzie
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
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Diep DB, Nelson KL, Lawrence TS, Sellman BR, Tweten RK, Buckley JT. Expression and properties of an aerolysin--Clostridium septicum alpha toxin hybrid protein. Mol Microbiol 1999; 31:785-94. [PMID: 10048023 DOI: 10.1046/j.1365-2958.1999.01217.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aerolysin is a bilobal channel-forming toxin secreted by Aeromonas hydrophila. The alpha toxin produced by Clostridium septicum is homologous to the large lobe of aerolysin. However, it does not contain a region corresponding to the small lobe of the Aeromonas toxin, leading us to ask what the function of the small lobe is. We fused the small lobe of aerolysin to alpha toxin, producing a hybrid protein that should structurally resemble aerolysin. Unlike aerolysin, the hybrid was not secreted when expressed in Aeromonas salmonicida. The purified hybrid was activated by proteolytic processing in the same way as both parent proteins and, after activation, it formed oligomers that corresponded to the aerolysin heptamer. Like aerolysin, the hybrid was far more active than alpha toxin against human erythrocytes and mouse T lymphocytes. Both aerolysin and the hybrid bound to human glycophorin, and both were inhibited by preincubation with this erythrocyte glycoprotein, whereas alpha toxin was unaffected. We conclude that aerolysin contains two receptor binding sites, one for glycosyl-phosphatidylinositol-anchored proteins that is located in the large lobe and is also found in alpha toxin, and a second site, located in the small lobe, that binds a surface carbohydrate determinant.
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Affiliation(s)
- D B Diep
- Department of Biochemistry and Microbiology, University of Victoria, BC, Canada
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