1
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Turban A, Joussellin V, Piau C, Cattoir V, Launey Y, Eustache G. Fatal Clostridium septicum gas gangrene complicating ECMO: case report and review of literature. Access Microbiol 2024; 6:000825.v3. [PMID: 39104453 PMCID: PMC11299951 DOI: 10.1099/acmi.0.000825.v3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 06/21/2024] [Indexed: 08/07/2024] Open
Abstract
Clostridium septicum gas gangrene is a severe and deadly infection caused by an anaerobic, spore-forming, Gram-positive bacillus. As previously described, two entities are observed: traumatic and spontaneous (or non-traumatic) forms. In this report, we aim to describe the case of a fulminant and ultimately fatal C. septicum myonecrosis occurring in a patient who was first admitted for refractory cardiac arrest and placed on veino-arterial extracorporeal membrane oxygenation (ECMO). Building upon prior studies that have documented cases of spontaneous gas gangrene caused by C. septicum, we provide an updated compilation, focusing on microbiological characteristics of C. septicum, along with the diagnostic and therapeutic challenges associated with spontaneous gas gangrene. Additionally, the specific clinical situation of our case illustrates the seriousness of this infectious complication that combined both spontaneous and traumatic gas gangrene risk factors. We thus, discuss the antibiotic coverage prior to the initiation of ECMO procedure.
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Affiliation(s)
- Adrien Turban
- Department of Bacteriology, University Hospital of Rennes, 2 Rue Henri Le Guilloux, 35000 Rennes, France
| | - Vincent Joussellin
- Critical Care Unit, Department of Anaesthesia, Critical Care and Perioperative Medicine, University Hospital of Rennes, Rennes, France
| | - Caroline Piau
- Department of Bacteriology, University Hospital of Rennes, 2 Rue Henri Le Guilloux, 35000 Rennes, France
| | - Vincent Cattoir
- Department of Bacteriology, University Hospital of Rennes, 2 Rue Henri Le Guilloux, 35000 Rennes, France
- UMR_S 1230 BRM, Inserm/University of Rennes, 2 Avenue du Pr. Léon Bernard, 35000 Rennes, France
| | - Yoann Launey
- Critical Care Unit, Department of Anaesthesia, Critical Care and Perioperative Medicine, University Hospital of Rennes, Rennes, France
| | - Gabriel Eustache
- Critical Care Unit, Department of Anaesthesia, Critical Care and Perioperative Medicine, University Hospital of Rennes, Rennes, France
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2
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Popoff MR. Overview of Bacterial Protein Toxins from Pathogenic Bacteria: Mode of Action and Insights into Evolution. Toxins (Basel) 2024; 16:182. [PMID: 38668607 PMCID: PMC11054074 DOI: 10.3390/toxins16040182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 03/29/2024] [Accepted: 03/30/2024] [Indexed: 04/29/2024] Open
Abstract
Bacterial protein toxins are secreted by certain bacteria and are responsible for mild to severe diseases in humans and animals. They are among the most potent molecules known, which are active at very low concentrations. Bacterial protein toxins exhibit a wide diversity based on size, structure, and mode of action. Upon recognition of a cell surface receptor (protein, glycoprotein, and glycolipid), they are active either at the cell surface (signal transduction, membrane damage by pore formation, or hydrolysis of membrane compound(s)) or intracellularly. Various bacterial protein toxins have the ability to enter cells, most often using an endocytosis mechanism, and to deliver the effector domain into the cytosol, where it interacts with an intracellular target(s). According to the nature of the intracellular target(s) and type of modification, various cellular effects are induced (cell death, homeostasis modification, cytoskeleton alteration, blockade of exocytosis, etc.). The various modes of action of bacterial protein toxins are illustrated with representative examples. Insights in toxin evolution are discussed.
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Affiliation(s)
- Michel R Popoff
- Unité des Toxines Bactériennes, Institut Pasteur, Université Paris Cité, CNRS UMR 2001 INSERM U1306, F-75015 Paris, France
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Du J, Meki I, Li Q, Liu Y, Zhu Z, Pan C, Xia Y, Fu L, Yang L, Zhang S, Yin C, Luo Y, Wang T, Liu B, Chen X. A non-toxic recombinant Clostridium septicum α toxin induces protective immunity in mice and rabbits. Toxicon 2023; 233:107234. [PMID: 37543293 DOI: 10.1016/j.toxicon.2023.107234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 07/31/2023] [Accepted: 08/01/2023] [Indexed: 08/07/2023]
Abstract
Clostridium septicum alpha toxin (CSA) plays significant roles in ruminant's braxy. Genetically engineered CSA has been shown to function as a potential vaccine candidate in the prevention of the disease caused by Clostridium septicum. In the present study, we synthesized a non-toxic recombinant, rCSAm4/TMD by introducing four amino acid substitutions (C86L/N296A/H301A/W342A) and 11-amino-acid deletion (residues 212 to 222). Compared to recombinant CSA, rCSAm4/TMD showed no cytotoxicity to MDCK cells and was not fatal to mice. Moreover, rCSAm4/TMD could protect immunized mice against 5 × mouse LD100 (100% lethal dose) of crude CSA without obvious pathological change. Most importantly, rabbits immunized with rCSAm4/TMD produced high titers of neutralizing antibodies which protected the rabbits against crude CSA challenge. These data suggest that genetically detoxified rCSAm4/TMD is a potential subunit vaccine candidate against braxy.
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Affiliation(s)
- Jige Du
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Irene Meki
- International Atomic Energy Agency, Vienna, Austria
| | - Qianlin Li
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Ying Liu
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Zhen Zhu
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Chenfan Pan
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Yingju Xia
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Lizhi Fu
- Chongqing Academy of Animal Sciences, Chongqing, 402460, China
| | - Liu Yang
- Chongqing Academy of Animal Sciences, Chongqing, 402460, China
| | - Suhui Zhang
- Chongqing Academy of Animal Sciences, Chongqing, 402460, China
| | - Chunsheng Yin
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Yufeng Luo
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China
| | - Tuanjie Wang
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China.
| | - Bo Liu
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China; International Atomic Energy Agency, Vienna, Austria.
| | - Xiaoyun Chen
- China Institute of Veterinary Drug Control, Beijing, People's Republic of China.
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Yoon KA, Kim WJ, Lee S, Yang HS, Lee BH, Lee SH. Comparative analyses of the venom components in the salivary gland transcriptomes and saliva proteomes of some heteropteran insects. INSECT SCIENCE 2022; 29:411-429. [PMID: 34296820 DOI: 10.1111/1744-7917.12955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Salivary gland-specific transcriptomes of nine heteropteran insects with distinct feeding strategies (predaceous, hematophagous, and phytophagous) were analyzed and annotated to compare and identify the venom components as well as their expression profiles. The transcriptional abundance of venom genes was verified via quantitative real-time PCR. Hierarchical clustering of 30 representative differentially expressed venom genes from the nine heteropteran species revealed unique groups of salivary gland-specific genes depending on their feeding strategy. The commonly transcribed genes included a paralytic neurotoxin (arginine kinase), digestive enzymes (cathepsin and serine protease), an anti-inflammatory protein (cystatin), hexamerin, and an odorant binding protein. Both predaceous and hematophagous (bed bug) heteropteran species showed relatively higher transcription levels of genes encoding proteins involved in proteolysis and cytolysis, whereas phytophagous heteropterans exhibited little or no expression of these genes, but had a high expression of vitellogenin, a multifunctional allergen. Saliva proteomes from four representative species were also analyzed. All venom proteins identified via saliva proteome analysis were annotated using salivary gland transcriptome data. The proteomic expression profiles of venom proteins were in good agreement with the salivary gland-specific transcriptomic profiles. Our results indicate that profiling of the salivary gland transcriptome provides important information on the composition and evolutionary features of venoms depending on their feeding strategy.
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Affiliation(s)
- Kyungjae Andrew Yoon
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Korea
| | | | - Seungki Lee
- National Institute of Biological Resources, Environmental Research Complex, Incheon, Korea
| | - Hee-Sun Yang
- National Institute of Biological Resources, Environmental Research Complex, Incheon, Korea
| | - Byoung-Hee Lee
- National Institute of Biological Resources, Environmental Research Complex, Incheon, Korea
| | - Si Hyeock Lee
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Korea
- Department of Agricultural Biology, Seoul National University, Seoul, Korea
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5
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Sannigrahi A, Chattopadhyay K. Pore formation by pore forming membrane proteins towards infections. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:79-111. [PMID: 35034727 DOI: 10.1016/bs.apcsb.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last 25 years, the biology of membrane proteins, including the PFPs-membranes interactions is seeking attention for the development of successful drug molecules against a number of infectious diseases. Pore forming toxins (PFTs), the largest family of PFPs are considered as a group of virulence factors produced in a large number of pathogenic systems which include streptococcus, pneumonia, Staphylococcus aureus, E. coli, Mycobacterium tuberculosis, group A and B streptococci, Corynebacterium diphtheria and many more. PFTs are generally utilized by the disease causing pathogens to disrupt the host first line of defense i.e. host cell membranes through pore formation strategy. Although, pore formation is the principal mode of action of the PFTs but they can have additional adverse effects on the hosts including immune evasion. Recently, structural investigation of different PFTs have imparted the molecular mechanistic insights into how PFTs get transformed from its inactive state to active toxic state. On the basis of their structural entity, PFTs have been classified in different types and their mode of actions alters in terms of pore formation and corresponding cellular toxicity. Although pathogen genome analysis can identify the probable PFTs depending upon their structural diversity, there are so many PFTs which utilize the local environmental conditions to generate their pore forming ability using a novel strategy which is known as "conformational switch" of a protein. This conformational switch is considered as characteristics of the phase shifting proteins which were often utilized by many pathogenic systems to protect them from the invaders through allosteric communication between distant regions of the protein. In this chapter, we discuss the structure function relationships of PFTs and how activity of PFTs varies with the change in the environmental conditions has been explored. Finally, we demonstrate these structural insights to develop therapeutic potential to treat the infections caused by multidrug resistant pathogens.
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Affiliation(s)
- Achinta Sannigrahi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka, India.
| | - Krishnananda Chattopadhyay
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
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6
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Alves MLF, Ferreira MRA, Donassolo RA, Rodrigues RR, Conceição FR. Clostridium septicum: A review in the light of alpha-toxin and development of vaccines. Vaccine 2021; 39:4949-4956. [PMID: 34312008 DOI: 10.1016/j.vaccine.2021.07.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/31/2021] [Accepted: 07/08/2021] [Indexed: 10/20/2022]
Abstract
Clostridium septicum (CS) is a pathogen that can cause the death of animals in livestock worldwide through its main virulence factor, alpha-toxin (ATX). The aspects involved in diseases caused by ATX, such as economic impact, prevalence, and rapid clinical course, require that animals should be systematically immunized. This review provides an overview of CS in livestock farming and discusses current immunization methods. Currently, commercial vaccines available against CS involve the cultivation and inactivation of microorganisms and toxins using a time-consuming, expensive, and high biological risk-carrying production platform, and some have been reported to be ineffective. An alternative to this process is the recombinant DNA technology, although recombinant ATX obtained thus far is no longer efficient in stimulating protective antibody titers despite improvements in the production methods. On the other hand, immunized animals have highly favorable levels of survival when subjected to challenge tests, suggesting that high titers of circulating serum antibodies may not be representative of protection after immunization and that the non-immune cellular defenses associated with the particularities of the mechanism of action of ATX may be involved in the immune response of the host. To contribute to the future of global livestock farming through the development of more efficient recombinant vaccines, we suggest novel perspectives and strategies, such as the location of immunodominant epitopes, expression of relevant functional domains, and construction of chimeras, in the rational design of recombinant ATX.
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Affiliation(s)
- Mariliana Luiza Ferreira Alves
- Instituto Federal Sul-rio-grandense - IFSUL, Praça Vinte de Setembro, 455, Centro, CEP 96.015-360, Pelotas, RS, Brazil; Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, CP 354, CEP 96160-000, Pelotas, RS, Brazil.
| | - Marcos Roberto Alves Ferreira
- Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, CP 354, CEP 96160-000, Pelotas, RS, Brazil
| | - Rafael Amaral Donassolo
- Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, CP 354, CEP 96160-000, Pelotas, RS, Brazil
| | - Rafael Rodrigues Rodrigues
- Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, CP 354, CEP 96160-000, Pelotas, RS, Brazil
| | - Fabricio Rochedo Conceição
- Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, CP 354, CEP 96160-000, Pelotas, RS, Brazil
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7
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Complete Genome Sequence Analysis of Brevibacillus laterosporus Bl-zj Reflects its Potential Algicidal Response. Curr Microbiol 2021; 78:1409-1417. [DOI: 10.1007/s00284-021-02378-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 02/05/2021] [Indexed: 12/14/2022]
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8
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Parperis C, Wallace MI. Single-molecule imaging of pore-forming toxin dynamics in droplet interface bilayers. Methods Enzymol 2021; 649:431-459. [PMID: 33712195 DOI: 10.1016/bs.mie.2021.01.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Single-channel recording from pore-forming toxins (PFTs) provides a clear and direct molecular readout of toxin action. However to complete any mechanistic understanding of PFT behavior, this functional kinetic readout must be linked to the underlying changes in toxin structure, binding, conformation, or stoichiometry. Here we review how single-molecule imaging methods might be used to further our understanding of PFTs, and provide detailed practical guidance on the use of droplet interface bilayers as a method capable of examining both single-molecule fluorescence and single-channel electrical signals from PFTs.
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Affiliation(s)
- Christopher Parperis
- Department of Chemistry, Britannia House, King's College London, London, United Kingdom
| | - Mark I Wallace
- Department of Chemistry, Britannia House, King's College London, London, United Kingdom.
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9
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Evans JC, Tweten RK. How protein engineering has revealed the molecular mechanisms of pore-forming toxins. Methods Enzymol 2021; 649:47-70. [PMID: 33712197 DOI: 10.1016/bs.mie.2021.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Pore-forming proteins are found in prokaryotes, vertebrates, and invertebrates, and when involved in pathogenic processes they are classified as pore-forming toxins (PFTs). The use of gene engineering methods in combination with the information provided by the high-resolution crystal structures of the PFTs have allowed investigators to gain a deep understanding of their pore-forming mechanisms. In this chapter, we discuss how protein engineering has helped us and others to reveal the molecular mechanisms of pore formation by prokaryotic PFTs with an emphasis on our experiences with the cholesterol-dependent cytolysins (CDCs).
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Affiliation(s)
- Jordan C Evans
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Rodney K Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
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10
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Namdar F, Khanahmad H, Ghayour Z, Mirzaei F, Namdar A, Aghaei M, Izadi S, Khamesipour F, Hejazi SH. Evaluation of the Anti-Leishmanial Effect of Recombinant Clostridium α-Toxin. Infect Drug Resist 2020; 13:2355-2364. [PMID: 32765010 PMCID: PMC7369417 DOI: 10.2147/idr.s257561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/24/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Leishmaniasis is an infectious disease common in tropical and subtropical regions caused by the genus Leishmania, which is transmitted by the bite of female sandflies. In this study, we evaluate the anti-leishmanial effect of recombinant Clostridium α-toxin protein alone and the combination with glucantime through in vitro and in vivo. MATERIALS AND METHODS Production, expression, and purification of recombinant α-toxin were evaluated by SDS-PAGE and Western blotting techniques. The antileishmanial activities of the purified α-toxin plus and without glucantime were examined in vitro and in vivo. RESULTS The results indicated successful expression of α-toxin as a 48 kDa band on SDS-PAGE and Western blot methods. Also, evaluation of α-toxin IC50 showed the strong fatal effect of it, and glucantime on medium proliferated Leishmania promastigotes at lower concentrations compared with glucantime or α-toxin alone. Moreover, in vivo surveys showed that at the end of treatment courses, the mean of lesion size diminished in glucantime plus α-toxin treated mice versus negative control groups (p < 0.001). Also, there was a significant difference in the parasite burden of the spleen and liver of the control versus the test groups (p < 0.001). CONCLUSION The results showed recombinant α-toxin has synergistic effects with glucantime in destroying Leishmania parasites.
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Affiliation(s)
- Fatemeh Namdar
- Department of Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hossein Khanahmad
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Zahra Ghayour
- Department of Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Farzaneh Mirzaei
- Department of Parasitology and Mycology, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Azam Namdar
- Department of Community Medicine, School of Medicine, Fasa University of Medical Sciences, Fasa, Iran
| | - Maryam Aghaei
- Skin Diseases and Leishmaniasis Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shahrokh Izadi
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Faham Khamesipour
- Cellular and Molecular Research Center, Sabzevar University of Medical Sciences, Sabzevar, Iran
- Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Hossein Hejazi
- Department of Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Skin Diseases and Leishmaniasis Research Center, Department of Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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11
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Nagahama M, Takehara M, Rood JI. Histotoxic Clostridial Infections. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0024-2018. [PMID: 31350831 PMCID: PMC10957196 DOI: 10.1128/microbiolspec.gpp3-0024-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Indexed: 01/01/2023] Open
Abstract
The pathogenesis of clostridial myonecrosis or gas gangrene involves an interruption to the blood supply to the infected tissues, often via a traumatic wound, anaerobic growth of the infecting clostridial cells, the production of extracellular toxins, and toxin-mediated cell and tissue damage. This review focuses on host-pathogen interactions in Clostridium perfringens-mediated and Clostridium septicum-mediated myonecrosis. The major toxins involved are C. perfringens α-toxin, which has phospholipase C and sphingomyelinase activity, and C. septicum α-toxin, a β-pore-forming toxin that belongs to the aerolysin family. Although these toxins are cytotoxic, their effects on host cells are quite complex, with a range of intracellular cell signaling pathways induced by their action on host cell membranes.
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Affiliation(s)
- Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
| | - Masaya Takehara
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
| | - Julian I Rood
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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Podobnik M, Kisovec M, Anderluh G. Molecular mechanism of pore formation by aerolysin-like proteins. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630149 DOI: 10.1098/rstb.2016.0209] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Aerolysin-like pore-forming proteins are an important family of proteins able to efficiently damage membranes of target cells by forming transmembrane pores. They are characterized by a unique domain organization and mechanism of action that involves extensive conformational rearrangements. Although structures of soluble forms of many different members of this family are well understood, the structures of pores and their mechanism of assembly have been described only recently. The pores are characterized by well-defined β-barrels, which are devoid of any vestibular regions commonly found in other protein pores. Many members of this family are bacterial toxins; therefore, structural details of their transmembrane pores, as well as the mechanism of pore formation, are an important base for future drug design. Stability of pores and other properties, such as specificity for some cell surface molecules, make this family of proteins a useful set of molecular tools for molecular recognition and sensing in cell biology.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Marjetka Podobnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Matic Kisovec
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia
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13
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Kato H, Jochim RC, Gomez EA, Tsunekawa S, Valenzuela JG, Hashiguchi Y. Salivary gland transcripts of the kissing bug, Panstrongylus chinai, a vector of Chagas disease. Acta Trop 2017; 174:122-129. [PMID: 28690145 DOI: 10.1016/j.actatropica.2017.06.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 06/15/2017] [Accepted: 06/20/2017] [Indexed: 10/19/2022]
Abstract
The saliva of hematophagous arthropods injected during blood feeding contains potent pharmacologically active components to counteract the host hemostatic and inflammatory systems. In the present study, dominant salivary gland transcripts of Panstrongylus chinai, a vector of Chagas disease, were analyzed by sequencing randomly selected clones of the salivary gland cDNA library. This analysis showed that 56.5% of the isolated transcripts coded for putative secreted proteins, of which 73.7% coded for proteins belonging to the lipocalin family. The most abundant transcript of lipocalin family proteins was a homologue of pallidipin 2, an inhibitor of collagen-induced platelet aggregation of Triatoma pallidipennis. In addition, homologues of triafestin, an inhibitor of the kallikrein-kinin system of T. infestans, were identified as the dominant transcript. Other salivary transcripts encoding lipocalin family proteins had homology to triplatin (an inhibitor of platelet aggregation) and others with unknown function. Other than lipocalin family proteins, homologues of a Kazal-type serine protease inhibitor (putative anticoagulant), a hemolysin-like protein (unknown function), inositol polyphosphate 5-related protein (a regulator of membrane phosphoinositide), antigen 5-related protein (unknown function) and apyrase (platelet aggregation inhibitor) were identified.
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14
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Srivastava I, Aldape MJ, Bryant AE, Stevens DL. Spontaneous C. septicum gas gangrene: A literature review. Anaerobe 2017; 48:165-171. [PMID: 28780428 DOI: 10.1016/j.anaerobe.2017.07.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 10/19/2022]
Abstract
As the infectious disease paradigm undergoes a subtle shift, unusual infections associated with malignancy and immunosuppression are being increasingly reported. Spontaneous or non-traumatic Clostridium septicum infection is one such unusual infection which has gained prominence. This article aims to understand the pathophysiology, clinical manifestations and current trends in diagnosing and treating this rare but deadly infection. To understand the multifactorial causation of this infection a review of published cases of spontaneous C. septicum gas gangrene was performed and a total of 94 such cases were identified. Several factors were analyzed for each case: age, infection location and underlying illness, presenting signs and symptoms, neutropenia, gross pathology of the colon, antibiotic use, surgical intervention, and survival. A known or occult malignancy was present in 71% patients and an overall mortality of 67% was observed.
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15
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Vázquez-Iglesias L, Estefanell-Ucha B, Barcia-Castro L, Páez de la Cadena M, Álvarez-Chaver P, Ayude-Vázquez D, Rodríguez-Berrocal FJ. A simple electroelution method for rapid protein purification: isolation and antibody production of alpha toxin from Clostridium septicum. PeerJ 2017; 5:e3407. [PMID: 28652930 PMCID: PMC5483040 DOI: 10.7717/peerj.3407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/11/2017] [Indexed: 12/16/2022] Open
Abstract
Clostridium septicum produces a number of diseases in human and farm animals which, in most of the cases, are fatal without clinical intervention. Alpha toxin is an important agent and the unique lethal virulent factor produced by Clostridium septicum. This toxin is haemolytic, highly lethal and necrotizing activities but is being used as an antigen to develop animal vaccines. The aim of this study was to isolate the alpha toxin of Clostridium septicum and produce highly specific antibodies against it. In this work, we have developed a simple and efficient method for alpha toxin purification, based on electroelution that can be used as a time-saving method for purifying proteins. This technique avoids contamination by other proteins that could appear during other protein purification techniques such chromatography. The highly purified toxin was used to produce polyclonal antibodies. The specificity of the antibodies was tested by western blot and these antibodies can be applied to the quantitative determination of alpha toxin by slot blot.
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Affiliation(s)
- Lorena Vázquez-Iglesias
- Department of Biochemistry, Genetics and Immunology, Facultad de Biología, Universidad de Vigo, Vigo, Spain
| | - Borja Estefanell-Ucha
- Department of Biochemistry, Genetics and Immunology, Facultad de Biología, Universidad de Vigo, Vigo, Spain
| | - Leticia Barcia-Castro
- Department of Biochemistry, Genetics and Immunology, Facultad de Biología, Universidad de Vigo, Vigo, Spain
| | - María Páez de la Cadena
- Department of Biochemistry, Genetics and Immunology, Facultad de Biología, Universidad de Vigo, Vigo, Spain
| | - Paula Álvarez-Chaver
- Unidad de Proteómica, Servicio de Determinación Estructural, Proteómica y Genómica, CACTI, Universidad de Vigo, Spain
| | - Daniel Ayude-Vázquez
- Department of Biochemistry, Genetics and Immunology, Facultad de Biología, Universidad de Vigo, Vigo, Spain
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16
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Colletier JP, Sawaya MR, Gingery M, Rodriguez JA, Cascio D, Brewster AS, Michels-Clark T, Hice RH, Coquelle N, Boutet S, Williams GJ, Messerschmidt M, DePonte DP, Sierra RG, Laksmono H, Koglin JE, Hunter MS, Park HW, Uervirojnangkoorn M, Bideshi DK, Brunger AT, Federici BA, Sauter NK, Eisenberg DS. De novo phasing with X-ray laser reveals mosquito larvicide BinAB structure. Nature 2016; 539:43-47. [PMID: 27680699 PMCID: PMC5161637 DOI: 10.1038/nature19825] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 09/07/2016] [Indexed: 11/30/2022]
Abstract
BinAB is a naturally occurring paracrystalline larvicide distributed worldwide to combat the devastating diseases borne by mosquitoes. These crystals are composed of homologous molecules, BinA and BinB, which play distinct roles in the multi-step intoxication process, transforming from harmless, robust crystals, to soluble protoxin heterodimers, to internalized mature toxin, and finally toxic oligomeric pores. The small size of the crystals, 50 unit cells per edge, on average, has impeded structural characterization by conventional means. Here, we report the structure of BinAB solved de novo by serial-femtosecond crystallography at an X-ray free-electron laser (XFEL). The structure reveals tyrosine and carboxylate-mediated contacts acting as pH switches to release soluble protoxin in the alkaline larval midgut. An enormous heterodimeric interface appears responsible for anchoring BinA to receptor-bound BinB for co-internalization. Remarkably, this interface is largely composed of propeptides, suggesting that proteolytic maturation would trigger dissociation of the heterodimer and progression to pore formation.
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Affiliation(s)
| | - Michael R Sawaya
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, California 90095-1570, USA.,Howard Hughes Medical Institute, University of California, Los Angeles, California 90095-1570, USA
| | - Mari Gingery
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, California 90095-1570, USA
| | - Jose A Rodriguez
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, California 90095-1570, USA
| | - Duilio Cascio
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, California 90095-1570, USA
| | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Tara Michels-Clark
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert H Hice
- Department of Entomology and Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, California 92521, USA
| | - Nicolas Coquelle
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Sébastien Boutet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Garth J Williams
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Marc Messerschmidt
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Daniel P DePonte
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Raymond G Sierra
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Hartawan Laksmono
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Jason E Koglin
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Mark S Hunter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Hyun-Woo Park
- Department of Entomology and Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, California 92521, USA.,Department of Biological Sciences, California Baptist University, Riverside, California 92504, USA
| | - Monarin Uervirojnangkoorn
- Molecular and Cellular Physiology, and Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, USA
| | - Dennis K Bideshi
- Department of Entomology and Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, California 92521, USA.,Department of Biological Sciences, California Baptist University, Riverside, California 92504, USA
| | - Axel T Brunger
- Molecular and Cellular Physiology, and Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, USA
| | - Brian A Federici
- Department of Entomology and Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, California 92521, USA
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - David S Eisenberg
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, California 90095-1570, USA.,Howard Hughes Medical Institute, University of California, Los Angeles, California 90095-1570, USA
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17
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Cryo-EM structure of aerolysin variants reveals a novel protein fold and the pore-formation process. Nat Commun 2016; 7:12062. [PMID: 27405240 PMCID: PMC4947156 DOI: 10.1038/ncomms12062] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/25/2016] [Indexed: 12/19/2022] Open
Abstract
Owing to their pathogenical role and unique ability to exist both as soluble proteins and transmembrane complexes, pore-forming toxins (PFTs) have been a focus of microbiologists and structural biologists for decades. PFTs are generally secreted as water-soluble monomers and subsequently bind the membrane of target cells. Then, they assemble into circular oligomers, which undergo conformational changes that allow membrane insertion leading to pore formation and potentially cell death. Aerolysin, produced by the human pathogen Aeromonas hydrophila, is the founding member of a major PFT family found throughout all kingdoms of life. We report cryo-electron microscopy structures of three conformational intermediates and of the final aerolysin pore, jointly providing insight into the conformational changes that allow pore formation. Moreover, the structures reveal a protein fold consisting of two concentric β-barrels, tightly kept together by hydrophobic interactions. This fold suggests a basis for the prion-like ultrastability of aerolysin pore and its stoichiometry. Aerolysin is a secreted bacterial pore forming toxin that inserts into the host plasma membrane, potentially leading to cell death. Here the authors present Cryo-EM structures of aerolysin arrested at different stages of the pore formation process that provide insight into the conformational changes that allow pore formation.
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18
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Peraro MD, van der Goot FG. Pore-forming toxins: ancient, but never really out of fashion. Nat Rev Microbiol 2015; 14:77-92. [DOI: 10.1038/nrmicro.2015.3] [Citation(s) in RCA: 476] [Impact Index Per Article: 52.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Leone P, Bebeacua C, Opota O, Kellenberger C, Klaholz B, Orlov I, Cambillau C, Lemaitre B, Roussel A. X-ray and Cryo-electron Microscopy Structures of Monalysin Pore-forming Toxin Reveal Multimerization of the Pro-form. J Biol Chem 2015; 290:13191-201. [PMID: 25847242 DOI: 10.1074/jbc.m115.646109] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 11/06/2022] Open
Abstract
β-Barrel pore-forming toxins (β-PFT), a large family of bacterial toxins, are generally secreted as water-soluble monomers and can form oligomeric pores in membranes following proteolytic cleavage and interaction with cell surface receptors. Monalysin has been recently identified as a β-PFT that contributes to the virulence of Pseudomonas entomophila against Drosophila. It is secreted as a pro-protein that becomes active upon cleavage. Here we report the crystal and cryo-electron microscopy structure of the pro-form of Monalysin as well as the crystal structures of the cleaved form and of an inactive mutant lacking the membrane-spanning region. The overall structure of Monalysin displays an elongated shape, which resembles those of β-pore-forming toxins, such as Aerolysin, but is devoid of a receptor-binding domain. X-ray crystallography, cryo-electron microscopy, and light-scattering studies show that pro-Monalysin forms a stable doughnut-like 18-mer complex composed of two disk-shaped nonamers held together by N-terminal swapping of the pro-peptides. This observation is in contrast with the monomeric pro-form of the other β-PFTs that are receptor-dependent for membrane interaction. The membrane-spanning region of pro-Monalysin is fully buried in the center of the doughnut, suggesting that upon cleavage of pro-peptides, the two disk-shaped nonamers can, and have to, dissociate to leave the transmembrane segments free to deploy and lead to pore formation. In contrast with other toxins, the delivery of 18 subunits at once, nearby the cell surface, may be used to bypass the requirement of receptor-dependent concentration to reach the threshold for oligomerization into the pore-forming complex.
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Affiliation(s)
- Philippe Leone
- From the CNRS, Architecture et Fonction des Macromolécules Biologiques (AFMB), Unité Mixte de Recherche (UMR) 7257, 13288 Marseille, France, the Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, 13288 Marseille, France
| | - Cecilia Bebeacua
- From the CNRS, Architecture et Fonction des Macromolécules Biologiques (AFMB), Unité Mixte de Recherche (UMR) 7257, 13288 Marseille, France, the Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, 13288 Marseille, France
| | - Onya Opota
- the Global Health Institute, School of Life Sciences, École Polytechnique Fédérale Lausanne (EPFL), CH-1015 Lausanne, Switzerland, and
| | - Christine Kellenberger
- From the CNRS, Architecture et Fonction des Macromolécules Biologiques (AFMB), Unité Mixte de Recherche (UMR) 7257, 13288 Marseille, France, the Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, 13288 Marseille, France
| | - Bruno Klaholz
- the Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), CNRS, UMR 7104/INSERM U964/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Igor Orlov
- the Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), CNRS, UMR 7104/INSERM U964/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Christian Cambillau
- From the CNRS, Architecture et Fonction des Macromolécules Biologiques (AFMB), Unité Mixte de Recherche (UMR) 7257, 13288 Marseille, France, the Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, 13288 Marseille, France
| | - Bruno Lemaitre
- the Global Health Institute, School of Life Sciences, École Polytechnique Fédérale Lausanne (EPFL), CH-1015 Lausanne, Switzerland, and
| | - Alain Roussel
- From the CNRS, Architecture et Fonction des Macromolécules Biologiques (AFMB), Unité Mixte de Recherche (UMR) 7257, 13288 Marseille, France, the Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, 13288 Marseille, France,
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20
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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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21
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Lancto CA, Foster LK, Kromm MM, McComb B, Williams J, Luke J, Carnes A, Hodgson CP, Foster DN. A Noncytolytic α Toxin Recombinant Protein Protects Turkeys AgainstClostridium septicumChallenge. Avian Dis 2014; 58:566-71. [DOI: 10.1637/10826-032314-reg.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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Xu C, Wang BC, Yu Z, Sun M. Structural insights into Bacillus thuringiensis Cry, Cyt and parasporin toxins. Toxins (Basel) 2014; 6:2732-70. [PMID: 25229189 PMCID: PMC4179158 DOI: 10.3390/toxins6092732] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/26/2014] [Accepted: 08/28/2014] [Indexed: 11/30/2022] Open
Abstract
Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs) structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type α-PFTs, Cyt toxin type β-PFTs and aerolysin type β-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively.
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Affiliation(s)
- Chengchen Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Bi-Cheng Wang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
| | - Ziniu Yu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
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23
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Srisucharitpanit K, Yao M, Promdonkoy B, Chimnaronk S, Tanaka I, Boonserm P. Crystal structure of BinB: A receptor binding component of the binary toxin from Lysinibacillus sphaericus. Proteins 2014; 82:2703-12. [DOI: 10.1002/prot.24636] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/12/2014] [Accepted: 06/18/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Kanokporn Srisucharitpanit
- Institute of Molecular Biosciences, Mahidol University; Salaya, Phuttamonthon Nakhon Pathom 73170 Thailand
- Faculty of Allied Health Science; Burapha University, Saensook; Muang District Chon Buri 20131 Thailand
| | - Min Yao
- Faculty of Advanced Life Sciences; Hokkaido University; Sapporo 060-0810 Japan
| | - Boonhiang Promdonkoy
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency; 113 Pahonyothin Road, Khlong Nueng Khlong Luang Pathum Thani 12120 Thailand
| | - Sarin Chimnaronk
- Institute of Molecular Biosciences, Mahidol University; Salaya, Phuttamonthon Nakhon Pathom 73170 Thailand
| | - Isao Tanaka
- Faculty of Advanced Life Sciences; Hokkaido University; Sapporo 060-0810 Japan
| | - Panadda Boonserm
- Institute of Molecular Biosciences, Mahidol University; Salaya, Phuttamonthon Nakhon Pathom 73170 Thailand
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24
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Mukamoto M, Kimura R, Hang'ombe MB, Kohda T, Kozaki S. Analysis of tryptophan-rich region in Clostridium septicum alpha-toxin involved with binding to glycosylphosphatidylinositol-anchored proteins. Microbiol Immunol 2013; 57:163-9. [PMID: 23278518 DOI: 10.1111/1348-0421.12017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/18/2012] [Accepted: 12/06/2012] [Indexed: 11/27/2022]
Abstract
Clostridium septicum alpha-toxin has a unique tryptophan-rich region ((302)NGYSEWDWKWV(312)) that consists of 11 amino acid residues near the C-terminus. Using mutant toxins, the contribution of individual amino acids in the tryptophan-rich region to cytotoxicity and binding to glycosylphosphatidylinositol (GPI)-anchored proteins was examined. For retention of maximum cytotoxic activity, W307 and W311 are essential residues and residue 309 has to be hydrophobic and possess an aromatic side chain, such as tryptophan or phenylalanine. When residue 308, which lies between tryptophans (W307 and W309) is changed from an acidic to a basic amino acid, the cytotoxic activity of the mutant is reduced to less than that of the wild type. It was shown by a toxin overlay assay that the cytotoxic activity of each mutant toxin correlates closely with affinity to GPI-anchored proteins. These findings indicate that the WDW_W sequence in the tryptophan-rich region plays an important role in the cytotoxic mechanism of alpha-toxin, especially in the binding to GPI-anchored proteins as cell receptors.
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Affiliation(s)
- Masafumi Mukamoto
- Laboratory of Veterinary Epidemiology, Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58 Rinku Orai-kita, Izumisano, Osaka, 598-8531, Japan. ‐u.ac.jp
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25
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Degiacomi MT, Iacovache I, Pernot L, Chami M, Kudryashev M, Stahlberg H, van der Goot FG, Dal Peraro M. Molecular assembly of the aerolysin pore reveals a swirling membrane-insertion mechanism. Nat Chem Biol 2013; 9:623-9. [PMID: 23912165 DOI: 10.1038/nchembio.1312] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 06/25/2013] [Indexed: 12/24/2022]
Abstract
Aerolysin is the founding member of a superfamily of β-pore-forming toxins whose pore structure is unknown. We have combined X-ray crystallography, cryo-EM, molecular dynamics and computational modeling to determine the structures of aerolysin mutants in their monomeric and heptameric forms, trapped at various stages of the pore formation process. A dynamic modeling approach based on swarm intelligence was applied, whereby the intrinsic flexibility of aerolysin extracted from new X-ray structures was used to fully exploit the cryo-EM spatial restraints. Using this integrated strategy, we obtained a radically new arrangement of the prepore conformation and a near-atomistic structure of the aerolysin pore, which is fully consistent with all of the biochemical data available so far. Upon transition from the prepore to pore, the aerolysin heptamer shows a unique concerted swirling movement, accompanied by a vertical collapse of the complex, ultimately leading to the insertion of a transmembrane β-barrel.
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Affiliation(s)
- Matteo T Degiacomi
- 1] Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. [2] [3]
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26
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Los FCO, Randis TM, Aroian RV, Ratner AJ. Role of pore-forming toxins in bacterial infectious diseases. Microbiol Mol Biol Rev 2013; 77:173-207. [PMID: 23699254 PMCID: PMC3668673 DOI: 10.1128/mmbr.00052-12] [Citation(s) in RCA: 299] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.
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Affiliation(s)
| | - Tara M. Randis
- Department of Pediatrics, Columbia University, New York, New York, USA
| | - Raffi V. Aroian
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, USA
| | - Adam J. Ratner
- Department of Pediatrics, Columbia University, New York, New York, USA
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27
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Cysteine-scanning mutagenesis supports the importance of Clostridium perfringens enterotoxin amino acids 80 to 106 for membrane insertion and pore formation. Infect Immun 2012; 80:4078-88. [PMID: 22966051 DOI: 10.1128/iai.00069-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Clostridium perfringens enterotoxin (CPE) causes the gastrointestinal symptoms of the second most common bacterial food-borne illness. Previous studies suggested that a region named TM1, which has amphipathic characteristics and spans from amino acids 81 to 106 of the native CPE protein, forms a β-hairpin involved in β-barrel pore formation. To further explore the potential role of TM1 in pore formation, the single Cys naturally present in CPE at residue 186 was first altered to alanine by mutagenesis; the resultant rCPE variant, named C186A, was shown to retain cytotoxic properties. Cys-scanning mutagenesis was then performed in which individual Cys mutations were introduced into each TM1 residue of the C186A variant. When those Cys variants were characterized, three variants were identified that exhibit reduced cytotoxicity despite possessing binding and oligomerization abilities similar to those of the C186A variant from which they were derived. Pronase challenge experiments suggested that the reduced cytotoxicity of those two Cys variants, i.e., the F91C and F95C variants, which model to the tip of the β-hairpin, was attributable to a lessened ability of these variants to insert into membranes after oligomerization. In contrast, another Cys variant, i.e., the G103C variant, with impaired cytotoxicity apparently inserted into membranes after oligomerization but could not form a pore with a fully functional channel. Collectively, these results support the TM1 region forming a β-hairpin as an important step in CPE insertion and pore formation. Furthermore, this work identifies the first amino acid residues specifically involved in those two steps in CPE action.
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Xue Z, Liu X, Pang Y, Yu T, Xiao R, Jin M, Han Y, Su P, Wang J, Lv L, Wu F, Li Q. Characterization, phylogenetic analysis and cDNA cloning of natterin-like gene from the blood of lamprey, Lampetra japonica. Immunol Lett 2012; 148:1-10. [PMID: 22914553 DOI: 10.1016/j.imlet.2012.08.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/01/2012] [Accepted: 08/05/2012] [Indexed: 12/24/2022]
Abstract
Lamprey as a "living fossil" of immunological origin and "rich treasure" of biological pharmaceutical development has caused attention of scholars. The cDNA library construction and EST sequencing of blood had been done previously in our lab, and bioinformatics analysis provided a gene fragment which is highly homologous with natterin family, named natterin-like. To elucidate the characterization and phylogeny of natterin-like genes in early evolution, we cloned the full-length cDNA of natterin-like gene from the blood of Lampetra japonica. The open reading frame of this sequence contained 942bp and encoded 313 amino acids, including a lectin-like domain and a pore-forming toxin-like domain. Using reverse transcription PCR, natterin-like mRNA was also detected in lamprey blood, kidney, heart, liver, medullary, gonad, but absent in lamprey intestine and gill. Our results suggested that in lampreys and most of other species, there might be only one natterin-like gene, which was fused by certain sequences during evolution and encoded proteins with more functions. It is similar between C terminal of natterin-like protein and Aerolysin in space structure and the lectin-like domain of natterin-like equivalent to glycoprotein binding motif of Aerolysin in function. We also propose that the defense mechanism against specific predators in historical evolution of lamprey. Our findings may provide insights into the function and characterization of natterin-like genes as well as other gene families in vertebrates and provide a foundation for identification and structural, functional, and evolutionary analyses of more natterin-like genes and other gene families.
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Affiliation(s)
- Zhuang Xue
- Institute of Marine Genomics & Proteomics, Liaoning Normal University, Dalian 116029, China
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Geny B, Popoff MR. Bacterial protein toxins and lipids: pore formation or toxin entry into cells. Biol Cell 2012; 98:667-78. [PMID: 17042742 DOI: 10.1042/bc20050082] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Lipids are hydrophobic molecules which play critical functions in cells, in particular, they are essential constituents of membranes, whereas bacterial toxins are mainly hydrophilic proteins. All bacterial toxins interact first with their target cells by recognizing a surface receptor, which is either a lipid or a lipid derivative, or another compound but in a lipid environment. Most bacterial toxins are PFTs (pore-forming toxins) which oligomerize and insert into the lipid bilayer. A common mechanism of action involves the formation of a beta-barrel structure, resulting from the assembly of individual beta-hairpin(s) from individual monomers. An essential step for intracellular active toxins is to translocate their enzymatic part into the cytosol. Some toxins use a translocation mechanism based on pore formation similar to that of PFTs, others undergo a yet unclear 'chaperone' process.
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Affiliation(s)
- Blandine Geny
- Unité des Bactéries Anaérobies et Toxines, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris cedex 15, France
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Briggs DC, Naylor CE, Smedley JG, Lukoyanova N, Robertson S, Moss DS, McClane BA, Basak AK. Structure of the food-poisoning Clostridium perfringens enterotoxin reveals similarity to the aerolysin-like pore-forming toxins. J Mol Biol 2011; 413:138-49. [PMID: 21839091 DOI: 10.1016/j.jmb.2011.07.066] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/14/2011] [Accepted: 07/28/2011] [Indexed: 11/24/2022]
Abstract
Clostridium perfringens enterotoxin (CPE) is a major cause of food poisoning and antibiotic-associated diarrhea. Upon its release from C. perfringens spores, CPE binds to its receptor, claudin, at the tight junctions between the epithelial cells of the gut wall and subsequently forms pores in the cell membranes. A number of different complexes between CPE and claudin have been observed, and the process of pore formation has not been fully elucidated. We have determined the three-dimensional structure of the soluble form of CPE in two crystal forms by X-ray crystallography, to a resolution of 2.7 and 4.0 Å, respectively, and found that the N-terminal domain shows structural homology with the aerolysin-like β-pore-forming family of proteins. We show that CPE forms a trimer in both crystal forms and that this trimer is likely to be biologically relevant but is not the active pore form. We use these data to discuss models of pore formation.
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Affiliation(s)
- David C Briggs
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, UK
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Angulo I, Acebrón I, de las Rivas B, Muñoz R, Rodríguez-Crespo I, Menéndez M, García P, Tateno H, Goldstein IJ, Pérez-Agote B, Mancheño JM. High-resolution structural insights on the sugar-recognition and fusion tag properties of a versatile β-trefoil lectin domain from the mushroom Laetiporus sulphureus. Glycobiology 2011; 21:1349-61. [PMID: 21632870 DOI: 10.1093/glycob/cwr074] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In this work, we analyzed at high resolution the sugar-binding mode of the recombinant N-terminal ricin-B domain of the hemolytic protein LSLa (LSL(150)) from the mushroom Laetiporus sulphureus and also provide functional in vitro evidence suggesting that, together with its putative receptor-binding role, this module may also increase the solubility of its membrane pore-forming partner. We first demonstrate that recombinant LSL(150) behaves as an autonomous folding unit and an active lectin. We have determined its crystal structure at 1.47 Å resolution and also that of the [LSL(150):(lactose)β, γ)] binary complex at 1.67 Å resolution. This complex reveals two lactose molecules bound to the β and γ sites of LSL(150), respectively. Isothermal titration calorimetry indicates that LSL(150) binds two lactoses in solution with highly different affinities. Also, we test the working hypothesis that LSL(150) exhibits in vivo properties typical of solubility tags. With this aim, we have fused an engineered version of LSL(150) (LSL(t)) to the N-terminal end of various recombinant proteins. All the designed LSL(150)-tagged fusion proteins were successfully produced at high yield, and furthermore, the target proteins were purified by a straightforward affinity procedure on agarose-based matrices due to the excellent properties of LSL(150) as an affinity tag. An optimized protocol for target protein purification was devised, which involved removal of the LSL(150) tag through in-column cleavage of the fusion proteins with His(6)-tagged TEV endoprotease. These results permitted to set up a novel, lectin-based system for production and purification of recombinant proteins in E. coli cells with attractive biotechnological applications.
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Affiliation(s)
- Iván Angulo
- Departamento de Cristalografía y Biología Estructural, Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid, Spain
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Bokori-Brown M, Savva CG, Fernandes da Costa SP, Naylor CE, Basak AK, Titball RW. Molecular basis of toxicity of Clostridium perfringens epsilon toxin. FEBS J 2011; 278:4589-601. [PMID: 21518257 DOI: 10.1111/j.1742-4658.2011.08140.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Clostridium perfringens ε-toxin is produced by toxinotypes B and D strains. The toxin is the aetiological agent of dysentery in newborn lambs but is also associated with enteritis and enterotoxaemia in goats, calves and foals. It is considered to be a potential biowarfare or bioterrorism agent by the US Government Centers for Disease Control and Prevention. The relatively inactive 32.9 kDa prototoxin is converted to active mature toxin by proteolytic cleavage, either by digestive proteases of the host, such as trypsin and chymotrypsin, or by C. perfringens λ-protease. In vivo, the toxin appears to target the brain and kidneys, but relatively few cell lines are susceptible to the toxin, and most work has been carried out using Madin-Darby canine kidney (MDCK) cells. The binding of ε-toxin to MDCK cells and rat synaptosomal membranes is associated with the formation of a stable, high molecular weight complex. The crystal structure of ε-toxin reveals similarity to aerolysin from Aeromonas hydrophila, parasporin-2 from Bacillus thuringiensis and a lectin from Laetiporus sulphureus. Like these toxins, ε-toxin appears to form heptameric pores in target cell membranes. The exquisite specificity of the toxin for specific cell types suggests that it binds to a receptor found only on these cells.
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Affiliation(s)
- Monika Bokori-Brown
- Biosciences, College of Life and Environmental Sciences, University of Exeter, UK
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Kitadokoro K, Nishimura K, Kamitani S, Fukui-Miyazaki A, Toshima H, Abe H, Kamata Y, Sugita-Konishi Y, Yamamoto S, Karatani H, Horiguchi Y. Crystal structure of Clostridium perfringens enterotoxin displays features of beta-pore-forming toxins. J Biol Chem 2011; 286:19549-55. [PMID: 21489981 DOI: 10.1074/jbc.m111.228478] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Clostridium perfringens enterotoxin (CPE) is a cause of food poisoning and is considered a pore-forming toxin, which damages target cells by disrupting the selective permeability of the plasma membrane. However, the pore-forming mechanism and the structural characteristics of the pores are not well documented. Here, we present the structure of CPE determined by x-ray crystallography at 2.0 Å. The overall structure of CPE displays an elongated shape, composed of three distinct domains, I, II, and III. Domain I corresponds to the region that was formerly referred to as C-CPE, which is responsible for binding to the specific receptor claudin. Domains II and III comprise a characteristic module, which resembles those of β-pore-forming toxins such as aerolysin, C. perfringens ε-toxin, and Laetiporus sulfureus hemolytic pore-forming lectin. The module is mainly made up of β-strands, two of which span its entire length. Domain II and domain III have three short β-strands each, by which they are distinguished. In addition, domain II has an α-helix lying on the β-strands. The sequence of amino acids composing the α-helix and preceding β-strand demonstrates an alternating pattern of hydrophobic residues that is characteristic of transmembrane domains forming β-barrel-made pores. These structural features imply that CPE is a β-pore-forming toxin. We also hypothesize that the transmembrane domain is inserted into the membrane upon the buckling of the two long β-strands spanning the module, a mechanism analogous to that of the cholesterol-dependent cytolysins.
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Affiliation(s)
- Kengo Kitadokoro
- Graduate School of Science and Technology, Department of Biomolecular Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto, Japan
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Lonchamp E, Dupont JL, Wioland L, Courjaret R, Mbebi-Liegeois C, Jover E, Doussau F, Popoff MR, Bossu JL, de Barry J, Poulain B. Clostridium perfringens epsilon toxin targets granule cells in the mouse cerebellum and stimulates glutamate release. PLoS One 2010; 5:e13046. [PMID: 20941361 PMCID: PMC2948003 DOI: 10.1371/journal.pone.0013046] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 09/03/2010] [Indexed: 11/19/2022] Open
Abstract
Epsilon toxin (ET) produced by C. perfringens types B and D is a highly potent pore-forming toxin. ET-intoxicated animals express severe neurological disorders that are thought to result from the formation of vasogenic brain edemas and indirect neuronal excitotoxicity. The cerebellum is a predilection site for ET damage. ET has been proposed to bind to glial cells such as astrocytes and oligodendrocytes. However, the possibility that ET binds and attacks the neurons remains an open question. Using specific anti-ET mouse polyclonal antibodies and mouse brain slices preincubated with ET, we found that several brain structures were labeled, the cerebellum being a prominent one. In cerebellar slices, we analyzed the co-staining of ET with specific cell markers, and found that ET binds to the cell body of granule cells, oligodendrocytes, but not astrocytes or nerve endings. Identification of granule cells as neuronal ET targets was confirmed by the observation that ET induced intracellular Ca(2+) rises and glutamate release in primary cultures of granule cells. In cultured cerebellar slices, whole cell patch-clamp recordings of synaptic currents in Purkinje cells revealed that ET greatly stimulates both spontaneous excitatory and inhibitory activities. However, pharmacological dissection of these effects indicated that they were only a result of an increased granule cell firing activity and did not involve a direct action of the toxin on glutamatergic nerve terminals or inhibitory interneurons. Patch-clamp recordings of granule cell somata showed that ET causes a decrease in neuronal membrane resistance associated with pore-opening and depolarization of the neuronal membrane, which subsequently lead to the firing of the neuronal network and stimulation of glutamate release. This work demonstrates that a subset of neurons can be directly targeted by ET, suggesting that part of ET-induced neuronal damage observed in neuronal tissue is due to a direct effect of ET on neurons.
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Affiliation(s)
- Etienne Lonchamp
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Jean-Luc Dupont
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Laetitia Wioland
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Raphaël Courjaret
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Corinne Mbebi-Liegeois
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Emmanuel Jover
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Frédéric Doussau
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Michel R. Popoff
- Unité des Anaérobies et Leurs Toxines, Institut Pasteur à Paris, Paris, France
| | - Jean-Louis Bossu
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Jean de Barry
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
| | - Bernard Poulain
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France
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Laetiporus sulphureus lectin and aerolysin protein family. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 677:67-80. [PMID: 20687481 DOI: 10.1007/978-1-4419-6327-7_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The parasitic mushroom Laetiporus sulphureus produces a family of lectins (LSL's) sharing 80-90% sequence identity that possesses a low but significant sequence similarity to the bacterial pore-forming toxins mosquitocidal toxin Mtx-2 from Bacillus sphaericus and a toxin from Clostridium septicum. The crystal structure of one member of the L. sulphureus lectins family (LSLa) reveals unexpected structural similarities to the 1-pore-forming toxins from the aerolysin family, namely, aerolysin from the Gram-negative bacterium Aeromonas hydrophila, epsilon-toxin from Clostridium perfringens and parasporin from B. thuringiensis. This similarity presumably indicates that the hemolytic activity of LSLa proceeds through a molecular mechanism that involves the formation of oligomeric transmembrane beta-barrels. Comparison of the crystal structures of the above mentioned proteins reveals common pore-forming modules, which are then distributed both in bacteria and fungi. Currently, it can be stated that the above three dimensional structures have been key in revealing structural similarities that were elusive at the sequence level. A potential corollary from this is that structural studies aimed at determining high resolution structures of aerolysin-like pore-forming toxins, whose biological activity involves large conformational changes, are mandatory to define protein domains or structural motifs with membrane-binding properties.
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Abstract
Clostridia produce the highest number of toxins of any type of bacteria and are involved in severe diseases in humans and other animals. Most of the clostridial toxins are pore-forming toxins responsible for gangrenes and gastrointestinal diseases. Among them, perfringolysin has been extensively studied and it is the paradigm of the cholesterol-dependent cytolysins, whereas Clostridium perfringens epsilon-toxin and Clostridium septicum alpha-toxin, which are related to aerolysin, are the prototypes of clostridial toxins that form small pores. Other toxins active on the cell surface possess an enzymatic activity, such as phospholipase C and collagenase, and are involved in the degradation of specific cell-membrane or extracellular-matrix components. Three groups of clostridial toxins have the ability to enter cells: large clostridial glucosylating toxins, binary toxins and neurotoxins. The binary and large clostridial glucosylating toxins alter the actin cytoskeleton by enzymatically modifying the actin monomers and the regulatory proteins from the Rho family, respectively. Clostridial neurotoxins proteolyse key components of neuroexocytosis. Botulinum neurotoxins inhibit neurotransmission at neuromuscular junctions, whereas tetanus toxin targets the inhibitory interneurons of the CNS. The high potency of clostridial toxins results from their specific targets, which have an essential cellular function, and from the type of modification that they induce. In addition, clostridial toxins are useful pharmacological and biological tools.
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Affiliation(s)
- Michel R Popoff
- Institut Pasteur, Bactéries Anaérobies et Toxines, 75724 Paris cedex 15, France.
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Sher D, Zlotkin E. A hydra with many heads: Protein and polypeptide toxins from hydra and their biological roles. Toxicon 2009; 54:1148-61. [DOI: 10.1016/j.toxicon.2009.02.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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A repertoire of the dominant transcripts from the salivary glands of the blood-sucking bug, Triatoma dimidiata, a vector of Chagas disease. INFECTION GENETICS AND EVOLUTION 2009; 10:184-91. [PMID: 19900580 DOI: 10.1016/j.meegid.2009.10.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 10/10/2009] [Accepted: 10/31/2009] [Indexed: 11/27/2022]
Abstract
Triatoma (T.) dimidiata is a hematophagous Hemiptera and a main vector of Chagas disease. The saliva of this and other blood-sucking insects contains potent pharmacologically active components that assist them in counteracting the host hemostatic and inflammatory systems during blood feeding. To describe the repertoire of potential bioactive salivary molecules from this insect, a number of randomly selected transcripts from the salivary gland cDNA library of T. dimidiata were sequenced and analyzed. This analysis showed that 77.5% of the isolated transcripts coded for putative secreted proteins, and 89.9% of these coded for variants of the lipocalin family proteins. The most abundant transcript was a homologue of procalin, the major allergen of T. protracta saliva, and contributed more than 50% of the transcripts coding for putative secreted proteins, suggesting that it may play an important role in the blood-feeding process. Other salivary transcripts encoding lipocalin family proteins had homology to triabin (a thrombin inhibitor), triafestin (an inhibitor of kallikrein-kinin system), pallidipin (an inhibitor of collagen-induced platelet aggregation) and others with unknown function.
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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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Kennedy CL, Smith DJ, Lyras D, Chakravorty A, Rood JI. Programmed cellular necrosis mediated by the pore-forming alpha-toxin from Clostridium septicum. PLoS Pathog 2009; 5:e1000516. [PMID: 19609357 PMCID: PMC2705182 DOI: 10.1371/journal.ppat.1000516] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 06/19/2009] [Indexed: 02/04/2023] Open
Abstract
Programmed necrosis is a mechanism of cell death that has been described for neuronal excitotoxicity and ischemia/reperfusion injury, but has not been extensively studied in the context of exposure to bacterial exotoxins. The α-toxin of Clostridium septicum is a β-barrel pore-forming toxin and a potent cytotoxin; however, the mechanism by which it induces cell death has not been elucidated in detail. We report that α-toxin formed Ca2+-permeable pores in murine myoblast cells, leading to an increase in intracellular Ca2+ levels. This Ca2+ influx did not induce apoptosis, as has been described for other small pore-forming toxins, but a cascade of events consistent with programmed necrosis. Ca2+ influx was associated with calpain activation and release of cathepsins from lysosomes. We also observed deregulation of mitochondrial activity, leading to increased ROS levels, and dramatically reduced levels of ATP. Finally, the immunostimulatory histone binding protein HMGB1 was found to be released from the nuclei of α-toxin-treated cells. Collectively, these data show that α-toxin initiates a multifaceted necrotic cell death response that is consistent with its essential role in C. septicum-mediated myonecrosis and sepsis. We postulate that cellular intoxication with pore-forming toxins may be a major mechanism by which programmed necrosis is induced. Clostridium septicum is a highly virulent pathogen that causes spontaneous gas gangrene or clostridial myonecrosis. The essential virulence factor of C. septicum is a β-barrel toxin, α-toxin, that forms small pores in host cell membranes. This toxin is frequently described as a hemolysin, because the formation of these pores causes lysis of red blood cell cells due to membrane disruption. However, this description does not recognize additional effects that may be observed in nucleated host cells, which are more sensitive to α-toxin. We investigated how nucleated cells responded to α-toxin by treating a physiologically relevant muscle cell line with purified toxin and monitoring the response using various assays. We observed α-toxin-mediated programmed cellular necrosis that culminated in the release of the immunostimulatory molecule, HMGB1. This mechanism of cell death induction is consistent with the extensive necrosis that is evident in C. septicum-mediated myonecrosis and with the overwhelming sepsis that frequently contributes to the high mortality rate. These results represent an important advance in the understanding of the toxicity of β-barrel pore-forming toxins and how they may contribute to necrotic and systemic disease pathology.
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Affiliation(s)
- Catherine L. Kennedy
- Australian Bacterial Pathogenesis Research Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Danielle J. Smith
- Australian Research Council Centre for Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Dena Lyras
- Australian Bacterial Pathogenesis Research Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Anjana Chakravorty
- Australian Bacterial Pathogenesis Research Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Julian I. Rood
- Australian Bacterial Pathogenesis Research Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Australian Research Council Centre for Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- * E-mail:
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Akiba T, Abe Y, Kitada S, Kusaka Y, Ito A, Ichimatsu T, Katayama H, Akao T, Higuchi K, Mizuki E, Ohba M, Kanai R, Harata K. Crystal Structure of the Parasporin-2 Bacillus thuringiensis Toxin That Recognizes Cancer Cells. J Mol Biol 2009; 386:121-33. [PMID: 19094993 DOI: 10.1016/j.jmb.2008.12.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 11/30/2008] [Accepted: 12/02/2008] [Indexed: 11/30/2022]
Affiliation(s)
- Toshihiko Akiba
- Biological Information Research Center, AIST, Tsukuba, Ibaraki 305-8566, Japan.
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Pore-forming activity of alpha-toxin is essential for clostridium septicum-mediated myonecrosis. Infect Immun 2009; 77:943-51. [PMID: 19139192 DOI: 10.1128/iai.01267-08] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium septicum alpha-toxin is a beta-barrel pore-forming cytolysin that is functionally similar to aerolysin. Residues important in receptor binding, oligomerization, and pore formation have been identified; however, little is known about the activity of the toxin in an infection, although it is essential for disease. We have now shown that deletion of a small portion of the transmembrane domain, so that the toxin is no longer able to form pores, completely abrogates its ability to contribute to disease, as does replacement of the sole cysteine residue with leucine. However, although previous biochemical and cytotoxicity assays clearly indicated that mutations in residues important in oligomerization, binding, and prepore conversion greatly reduced activity or rendered the toxin inactive, once the mutated toxins were overexpressed by the natural host in the context of an infection it was found they were able to cause disease in a mouse model of myonecrosis. These results highlight the importance of testing the activity of virulence determinants in the normal host background and in an infectious disease context and provide unequivocal evidence that it is the ability of alpha-toxin to form a pore that confers its toxicity in vivo.
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Manich M, Knapp O, Gibert M, Maier E, Jolivet-Reynaud C, Geny B, Benz R, Popoff MR. Clostridium perfringens delta toxin is sequence related to beta toxin, NetB, and Staphylococcus pore-forming toxins, but shows functional differences. PLoS One 2008; 3:e3764. [PMID: 19018299 PMCID: PMC2583947 DOI: 10.1371/journal.pone.0003764] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 10/19/2008] [Indexed: 11/18/2022] Open
Abstract
Clostridium perfringens produces numerous toxins, which are responsible for severe diseases in man and animals. Delta toxin is one of the three hemolysins released by a number of C. perfringens type C and possibly type B strains. Delta toxin was characterized to be cytotoxic for cells expressing the ganglioside GM2 in their membrane. Here we report the genetic characterization of Delta toxin and its pore forming activity in lipid bilayers. Delta toxin consists of 318 amino acids, its 28 N-terminal amino acids corresponding to a signal peptide. The secreted Delta toxin (290 amino acids; 32619 Da) is a basic protein (pI 9.1) which shows a significant homology with C. perfringens Beta toxin (43% identity), with C. perfringens NetB (40% identity) and, to a lesser extent, with Staphylococcus aureus alpha toxin and leukotoxins. Recombinant Delta toxin showed a preference for binding to GM2, in contrast to Beta toxin, which did not bind to gangliosides. It is hemolytic for sheep red blood cells and cytotoxic for HeLa cells. In artificial diphytanoyl phosphatidylcholine membranes, Delta and Beta toxin formed channels. Conductance of the channels formed by Delta toxin, with a value of about 100 pS to more than 1 nS in 1 M KCl and a membrane potential of 20 mV, was higher than those formed by Beta toxin and their distribution was broader. The results of zero-current membrane potential measurements and single channel experiments suggest that Delta toxin forms slightly anion-selective channels, whereas the Beta toxin channels showed a preference for cations under the same conditions. C. perfringens Delta toxin shows a significant sequence homolgy with C. perfringens Beta and NetB toxins, as well as with S. aureus alpha hemolysin and leukotoxins, but exhibits different channel properties in lipid bilayers. In contrast to Beta toxin, Delta toxin recognizes GM2 as receptor and forms anion-selective channels.
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Affiliation(s)
- Maria Manich
- Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France
| | - Oliver Knapp
- Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France
- Lehrstuhl für Biotechnologie, Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Würzburg, Germany
| | - Maryse Gibert
- Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France
| | - Elke Maier
- Lehrstuhl für Biotechnologie, Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Würzburg, Germany
| | | | - Blandine Geny
- Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France
| | - Roland Benz
- Lehrstuhl für Biotechnologie, Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Würzburg, Germany
| | - Michel R. Popoff
- Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France
- * E-mail:
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Solubilization, activation, and insecticidal activity of Bacillus thuringiensis serovar thompsoni HD542 crystal proteins. Appl Environ Microbiol 2008; 74:7145-51. [PMID: 18836017 DOI: 10.1128/aem.00752-08] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cry15Aa protein, produced by Bacillus thuringiensis serovar thompsoni HD542 in a crystal together with a 40-kDa accompanying protein, is one of a small group of nontypical, less well-studied members of the Cry family of insecticidal proteins and may provide an alternative for the more commonly used Cry proteins in insect pest management. In this paper, we describe the characterization of the Cry15Aa and 40-kDa protein's biochemical and insecticidal properties and the mode of action. Both proteins were solubilized above pH 10 in vitro. Incubation of solubilized crystal proteins with trypsin or insect midgut extracts rapidly processed the 40-kDa protein to fragments too small to be detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas the Cry15 protein yielded a stable product of approximately 30 kDa. Protein N-terminal sequencing showed that Cry15 processing occurs exclusively at the C-terminal end. Cry15 protein showed in vitro hemolytic activity, which was greatly enhanced by preincubation with trypsin or insect gut extract. Larvae of the lepidopteran insects Manduca sexta, Cydia pomonella, and Pieris rapae were susceptible to crystals, and presolubilization of the crystals enhanced activity to P. rapae. Activity for all three species was enhanced by preincubation with trypsin. Larvae of Helicoverpa armigera and Spodoptera exigua were relatively insensitive to crystals, and activity against these insects was not enhanced by prior solubilization or trypsin treatment. The 40-kDa crystal protein showed no activity in the insects tested, nor did its addition or coexpression in Escherichia coli increase the activity of Cry15 in insecticidal and hemolytic assays.
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Anderluh G, Lakey JH. Disparate proteins use similar architectures to damage membranes. Trends Biochem Sci 2008; 33:482-90. [PMID: 18778941 DOI: 10.1016/j.tibs.2008.07.004] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 06/22/2008] [Accepted: 07/24/2008] [Indexed: 01/30/2023]
Abstract
Membrane disruption can efficiently alter cellular function; indeed, pore-forming toxins (PFTs) are well known as important bacterial virulence factors. However, recent data have revealed that structures similar to those found in PFTs are found in membrane active proteins across disparate phyla. Many similarities can be identified only at the 3D-structural level. Of note, domains found in membrane-attack complex proteins of complement and perforin (MACPF) resemble cholesterol-dependent cytolysins from Gram-positive bacteria, and the Bcl family of apoptosis regulators share similar architectures with Escherichia coli pore-forming colicins. These and other correlations provide considerable help in understanding the structural requirements for membrane binding and pore formation.
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Affiliation(s)
- Gregor Anderluh
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000, Ljubljana, Slovenia.
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48
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Iacovache I, van der Goot FG, Pernot L. Pore formation: an ancient yet complex form of attack. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1611-23. [PMID: 18298943 DOI: 10.1016/j.bbamem.2008.01.026] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/03/2008] [Accepted: 01/04/2008] [Indexed: 02/07/2023]
Abstract
Bacteria, as well as higher organisms such as sea anemones or earthworms, have developed sophisticated virulence factors such as the pore-forming toxins (PFTs) to mount their attack against the host. One of the most fascinating aspects of PFTs is that they can adopt a water-soluble form at the beginning of their lifetime and become an integral transmembrane protein in the membrane of the target cells. There is a growing understanding of the sequence of events and the various conformational changes undergone by these toxins in order to bind to the host cell surface, to penetrate the cell membranes and to achieve pore formation. These points will be addressed in this review.
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Affiliation(s)
- Ioan Iacovache
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Station 15, Lausanne, Switzerland
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Assumpção TCF, Francischetti IMB, Andersen JF, Schwarz A, Santana JM, Ribeiro JMC. An insight into the sialome of the blood-sucking bug Triatoma infestans, a vector of Chagas' disease. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2008; 38:213-32. [PMID: 18207082 PMCID: PMC2262853 DOI: 10.1016/j.ibmb.2007.11.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 11/06/2007] [Accepted: 11/06/2007] [Indexed: 05/09/2023]
Abstract
Triatoma infestans is a hemiptera, vector of Chagas' disease that feeds exclusively on vertebrate blood in all life stages. Hematophagous insects' salivary glands (SG) produce potent pharmacological compounds that counteract host hemostasis, including anticlotting, antiplatelet, and vasodilatory molecules. To obtain a further insight into the salivary biochemical and pharmacological complexity of this insect, a cDNA library from its SG was randomly sequenced. Also, salivary proteins were submitted to two-dimensional gel (2D-gel) electrophoresis followed by MS analysis. We present the analysis of a set of 1534 (SG) cDNA sequences, 645 of which coded for proteins of a putative secretory nature. Most salivary proteins described as lipocalins matched peptide sequences obtained from proteomic results.
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Affiliation(s)
- Teresa C F Assumpção
- Laboratory of Host-Parasite Interface, University of Brasília, Brasília-DF 70.910-900, Brazil.
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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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