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Wang G, Fan C, Wang H, Jia C, Li X, Yang J, Zhang T, Gao S, Min X, Huang J. Type VI secretion system-associated FHA domain protein TagH regulates the hemolytic activity and virulence of Vibrio cholerae. Gut Microbes 2022; 14:2055440. [PMID: 35383540 PMCID: PMC8993066 DOI: 10.1080/19490976.2022.2055440] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The type VI secretion system (T6SS) and hemolysin HlyA are important virulence factors in Vibrio cholerae. The forkhead-associated (FHA) domain is a conserved phosphopeptide binding domain that exists in many regulatory modules. The FHA domain protein-encoding gene is conserved in the T6SS gene cluster and regulates the assembly and secretion of the T6SS. This study shows for the first time that the FHA domain protein TagH plays a role in controlling the hemolytic activity of V. cholerae, in addition to regulating the T6SS. TagH negatively regulates HlyA expression at the transcriptional and post-translational levels. The phosphopeptide binding sites of the FHA domain of TagH play a key role in the regulation of hemolytic activity. The deletion of tagH enhances the intestinal pathogenicity and extraintestinal invasion ability of V. cholerae, which mainly depend on the expression of HlyA. This study provides evidence that helps unravel the novel regulatory role of TagH in HlyA and provides critical insights which will aid in the development of strategies to manage HlyA.
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Affiliation(s)
- Guangli Wang
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
| | - Chan Fan
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Hui Wang
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Chengyi Jia
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Xiaoting Li
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Jianru Yang
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Tao Zhang
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Song Gao
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China
| | - Xun Min
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China,CONTACT Xun Min Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
| | - Jian Huang
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China,School of Laboratory Medicine, Zunyi Medical University, Zunyi, Guizhou, China,Jian Huang School of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi,Guizhou, China
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2
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Kulma M, Anderluh G. Beyond pore formation: reorganization of the plasma membrane induced by pore-forming proteins. Cell Mol Life Sci 2021; 78:6229-6249. [PMID: 34387717 PMCID: PMC11073440 DOI: 10.1007/s00018-021-03914-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/09/2021] [Accepted: 08/03/2021] [Indexed: 12/23/2022]
Abstract
Pore-forming proteins (PFPs) are a heterogeneous group of proteins that are expressed and secreted by a wide range of organisms. PFPs are produced as soluble monomers that bind to a receptor molecule in the host cell membrane. They then assemble into oligomers that are incorporated into the lipid membrane to form transmembrane pores. Such pore formation alters the permeability of the plasma membrane and is one of the most common mechanisms used by PFPs to destroy target cells. Interestingly, PFPs can also indirectly manipulate diverse cellular functions. In recent years, increasing evidence indicates that the interaction of PFPs with lipid membranes is not only limited to pore-induced membrane permeabilization but is also strongly associated with extensive plasma membrane reorganization. This includes lateral rearrangement and deformation of the lipid membrane, which can lead to the disruption of target cell function and finally death. Conversely, these modifications also constitute an essential component of the membrane repair system that protects cells from the lethal consequences of pore formation. Here, we provide an overview of the current knowledge on the changes in lipid membrane organization caused by PFPs from different organisms.
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Affiliation(s)
- Magdalena Kulma
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1001, Ljubljana, Slovenia.
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1001, Ljubljana, Slovenia
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3
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Ramamurthy T, Nandy RK, Mukhopadhyay AK, Dutta S, Mutreja A, Okamoto K, Miyoshi SI, Nair GB, Ghosh A. Virulence Regulation and Innate Host Response in the Pathogenicity of Vibrio cholerae. Front Cell Infect Microbiol 2020; 10:572096. [PMID: 33102256 PMCID: PMC7554612 DOI: 10.3389/fcimb.2020.572096] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023] Open
Abstract
The human pathogen Vibrio cholerae is the causative agent of severe diarrheal disease known as cholera. Of the more than 200 "O" serogroups of this pathogen, O1 and O139 cause cholera outbreaks and epidemics. The rest of the serogroups, collectively known as non-O1/non-O139 cause sporadic moderate or mild diarrhea and also systemic infections. Pathogenic V. cholerae circulates between nutrient-rich human gut and nutrient-deprived aquatic environment. As an autochthonous bacterium in the environment and as a human pathogen, V. cholerae maintains its survival and proliferation in these two niches. Growth in the gastrointestinal tract involves expression of several genes that provide bacterial resistance against host factors. An intricate regulatory program involving extracellular signaling inputs is also controlling this function. On the other hand, the ability to store carbon as glycogen facilitates bacterial fitness in the aquatic environment. To initiate the infection, V. cholerae must colonize the small intestine after successfully passing through the acid barrier in the stomach and survive in the presence of bile and antimicrobial peptides in the intestinal lumen and mucus, respectively. In V. cholerae, virulence is a multilocus phenomenon with a large functionally associated network. More than 200 proteins have been identified that are functionally linked to the virulence-associated genes of the pathogen. Several of these genes have a role to play in virulence and/or in functions that have importance in the human host or the environment. A total of 524 genes are differentially expressed in classical and El Tor strains, the two biotypes of V. cholerae serogroup O1. Within the host, many immune and biological factors are able to induce genes that are responsible for survival, colonization, and virulence. The innate host immune response to V. cholerae infection includes activation of several immune protein complexes, receptor-mediated signaling pathways, and other bactericidal proteins. This article presents an overview of regulation of important virulence factors in V. cholerae and host response in the context of pathogenesis.
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Affiliation(s)
| | - Ranjan K Nandy
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Asish K Mukhopadhyay
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shanta Dutta
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Ankur Mutreja
- Global Health-Infectious Diseases, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Keinosuke Okamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.,Collaborative Research Center of Okayama University for Infectious Diseases in India, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shin-Ichi Miyoshi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - G Balakrish Nair
- Microbiome Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Amit Ghosh
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
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4
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Guo RH, Gong Y, Kim SY, Rhee JH, Kim YR. DIDS inhibits Vibrio vulnificus cytotoxicity by interfering with TolC-mediated RtxA1 toxin secretion. Eur J Pharmacol 2020; 884:173407. [PMID: 32735984 DOI: 10.1016/j.ejphar.2020.173407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/10/2020] [Accepted: 07/23/2020] [Indexed: 12/28/2022]
Abstract
Vibrio vulnificus (V. vulnificus) infection, frequently resulting in fatal septicemia, has become a growing health concern worldwide. The present study aimed to explore the potential agents that could protect against V. vulnificus cytotoxicity, and to analyze the possible underlying mechanisms. First, we observed that 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt hydrate (DIDS) significantly suppressed V. vulnificus cytotoxicity to host cells by using a lactate dehydrogenase (LDH) assay. DIDS did not exhibit any effect on host cell viability, bacterial growth, microbial adhesion and swarming motility. DIDS effectively lowered V. vulnificus RtxA1 toxin-induced calcium influx into host mitochondria and RtxA1 binding to host cells. To further elucidate the underlying mechanism, the synthesis and secretion of RtxA1 toxin were investigated by Western blotting. Intriguingly, DIDS selectively inhibited the secretion of RtxA1 toxin, but did not influence its synthesis. Consequently, the outer membrane portal TolC, a key conduit for RtxA1 export coupled with tripartite efflux pumps, was examined by RT-PCR and Western blotting. We found that DIDS significantly reduced the expression of TolCV1 protein at the transcriptional level. Taken together, these results suggest that DIDS is a promising new paradigm as an antimicrobial drug that targets TolC-mediated toxin.
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Affiliation(s)
- Rui Hong Guo
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Republic of Korea
| | - Yue Gong
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Republic of Korea
| | - Soo Young Kim
- Clinical Vaccine R&D Center and Department of Microbiology, Chonnam National University Medical School, Republic of Korea
| | - Joon Haeng Rhee
- Clinical Vaccine R&D Center and Department of Microbiology, Chonnam National University Medical School, Republic of Korea
| | - Young Ran Kim
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Republic of Korea.
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5
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Brito C, Cabanes D, Sarmento Mesquita F, Sousa S. Mechanisms protecting host cells against bacterial pore-forming toxins. Cell Mol Life Sci 2019; 76:1319-1339. [PMID: 30591958 PMCID: PMC6420883 DOI: 10.1007/s00018-018-2992-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 12/06/2018] [Accepted: 12/10/2018] [Indexed: 12/19/2022]
Abstract
Pore-forming toxins (PFTs) are key virulence determinants produced and secreted by a variety of human bacterial pathogens. They disrupt the plasma membrane (PM) by generating stable protein pores, which allow uncontrolled exchanges between the extracellular and intracellular milieus, dramatically disturbing cellular homeostasis. In recent years, many advances were made regarding the characterization of conserved repair mechanisms that allow eukaryotic cells to recover from mechanical disruption of the PM membrane. However, the specificities of the cell recovery pathways that protect host cells against PFT-induced damage remain remarkably elusive. During bacterial infections, the coordinated action of such cell recovery processes defines the outcome of infected cells and is, thus, critical for our understanding of bacterial pathogenesis. Here, we review the cellular pathways reported to be involved in the response to bacterial PFTs and discuss their impact in single-cell recovery and infection.
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Affiliation(s)
- Cláudia Brito
- i3S-Instituto de Investigação e Inovação em Saúde, IBMC, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal
- Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Rua Jorge de Viterbo Ferreira 228, 4050-313, Porto, Portugal
| | - Didier Cabanes
- i3S-Instituto de Investigação e Inovação em Saúde, IBMC, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal
| | - Francisco Sarmento Mesquita
- i3S-Instituto de Investigação e Inovação em Saúde, IBMC, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.
- Global Health Institute, School of Life Science, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - Sandra Sousa
- i3S-Instituto de Investigação e Inovação em Saúde, IBMC, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.
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6
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Etxaniz A, González-Bullón D, Martín C, Ostolaza H. Membrane Repair Mechanisms against Permeabilization by Pore-Forming Toxins. Toxins (Basel) 2018; 10:E234. [PMID: 29890730 PMCID: PMC6024578 DOI: 10.3390/toxins10060234] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/04/2018] [Accepted: 06/07/2018] [Indexed: 01/29/2023] Open
Abstract
Permeabilization of the plasma membrane represents an important threat for any cell, since it compromises its viability by disrupting cell homeostasis. Numerous pathogenic bacteria produce pore-forming toxins that break plasma membrane integrity and cause cell death by colloid-osmotic lysis. Eukaryotic cells, in turn, have developed different ways to cope with the effects of such membrane piercing. Here, we provide a short overview of the general mechanisms currently proposed for plasma membrane repair, focusing more specifically on the cellular responses to membrane permeabilization by pore-forming toxins and presenting new data on the effects and cellular responses to the permeabilization by an RTX (repeats in toxin) toxin, the adenylate cyclase toxin-hemolysin secreted by the whooping cough bacterium Bordetella pertussis, which we have studied in the laboratory.
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Affiliation(s)
- Asier Etxaniz
- Biofisika Institute (UPV/EHU, CSIC) and University of the Basque Country (UPV/EHU) Parque Científico s/n, 48940 Leioa, Spain.
| | - David González-Bullón
- Biofisika Institute (UPV/EHU, CSIC) and University of the Basque Country (UPV/EHU) Parque Científico s/n, 48940 Leioa, Spain.
| | - César Martín
- Biofisika Institute (UPV/EHU, CSIC) and University of the Basque Country (UPV/EHU) Parque Científico s/n, 48940 Leioa, Spain.
| | - Helena Ostolaza
- Biofisika Institute (UPV/EHU, CSIC) and University of the Basque Country (UPV/EHU) Parque Científico s/n, 48940 Leioa, Spain.
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7
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Shubin AV, Demidyuk IV, Komissarov AA, Rafieva LM, Kostrov SV. Cytoplasmic vacuolization in cell death and survival. Oncotarget 2018; 7:55863-55889. [PMID: 27331412 PMCID: PMC5342458 DOI: 10.18632/oncotarget.10150] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 06/06/2016] [Indexed: 12/15/2022] Open
Abstract
Cytoplasmic vacuolization (also called cytoplasmic vacuolation) is a well-known morphological phenomenon observed in mammalian cells after exposure to bacterial or viral pathogens as well as to various natural and artificial low-molecular-weight compounds. Vacuolization often accompanies cell death; however, its role in cell death processes remains unclear. This can be attributed to studying vacuolization at the level of morphology for many years. At the same time, new data on the molecular mechanisms of the vacuole formation and structure have become available. In addition, numerous examples of the association between vacuolization and previously unknown cell death types have been reported. Here, we review these data to make a deeper insight into the role of cytoplasmic vacuolization in cell death and survival.
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Affiliation(s)
- Andrey V Shubin
- Laboratory of Protein Engineering, Institute of Molecular Genetics, Moscow, Russia.,Laboratory of Chemical Carcinogenesis, N.N. Blokhin Russian Cancer Research Center, Moscow, Russia.,Laboratory of Biologically Active Nanostructures, N.F. Gamaleya Institute of Epidemiology and Microbiology, Moscow, Russia
| | - Ilya V Demidyuk
- Laboratory of Protein Engineering, Institute of Molecular Genetics, Moscow, Russia
| | - Alexey A Komissarov
- Laboratory of Protein Engineering, Institute of Molecular Genetics, Moscow, Russia
| | - Lola M Rafieva
- Laboratory of Protein Engineering, Institute of Molecular Genetics, Moscow, Russia
| | - Sergey V Kostrov
- Laboratory of Protein Engineering, Institute of Molecular Genetics, Moscow, Russia
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8
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Abstract
Membrane repair emerges as an innate defense protecting target cells against bacterial pore-forming toxins. Here, we report the first paradigm of Ca2+-dependent repair following attack by a small β-pore-forming toxin, namely, plasmid-encoded phobalysin of Photobacterium damselae subsp. damselae. In striking contrast, Vibrio cholerae cytolysin, the closest ortholog of phobalysin, subverted repair. Mutational analysis uncovered a role of channel width in toxicity and repair. Thus, the replacement of serine at phobalysin´s presumed channel narrow point with the bulkier tryptophan, the corresponding residue in Vibrio cholerae cytolysin (W318), modulated Ca2+ influx, lysosomal exocytosis, and membrane repair. And yet, replacing tryptophan (W318) with serine in Vibrio cholerae cytolysin enhanced toxicity. The data reveal divergent strategies evolved by two related small β-pore-forming toxins to manipulate target cells: phobalysin leads to fulminant perturbation of ion concentrations, closely followed by Ca2+ influx-dependent membrane repair. In contrast, V. cholerae cytolysin causes insidious perturbations and escapes control by the cellular wounded membrane repair-like response. Previous studies demonstrated that large transmembrane pores, such as those formed by perforin or bacterial toxins of the cholesterol-dependent cytolysin family, trigger rapid, Ca2+ influx-dependent repair mechanisms. In contrast, recovery from attack by the small β-pore-forming Staphylococcus aureus alpha-toxin or aerolysin is slow in comparison and does not depend on extracellular Ca2+. To further elucidate the scope of Ca2+ influx-dependent repair and understand its limitations, we compared the cellular responses to phobalysin and V. cholerae cytolysin, two related small β-pore-forming toxins which create membrane pores of slightly different sizes. The data indicate that the channel width of a small β-pore-forming toxin is a critical determinant of both primary toxicity and susceptibility to Ca2+-dependent repair.
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9
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Miyashita SI, Sagane Y, Suzuki T, Matsumoto T, Niwa K, Watanabe T. "Non-Toxic" Proteins of the Botulinum Toxin Complex Exert In-vivo Toxicity. Sci Rep 2016; 6:31043. [PMID: 27507612 PMCID: PMC4978960 DOI: 10.1038/srep31043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 07/12/2016] [Indexed: 01/26/2023] Open
Abstract
The botulinum neurotoxin (BoNT) causes muscle paralysis and is the most potent toxin in nature. BoNT is associated with a complex of auxiliary “Non-Toxic” proteins, which constitute a large-sized toxin complex (L-TC). However, here we report that the “Non-Toxic” complex of serotype D botulinum L-TC, when administered to rats, exerts in-vivo toxicity on small-intestinal villi. Moreover, Serotype C and D of the “Non-Toxic” complex, but not BoNT, induced vacuole-formation in a rat intestinal epithelial cell line (IEC-6), resulting in cell death. Our results suggest that the vacuole was formed in a manner distinct from the mechanism by which Helicobacter pylori vacuolating toxin (VacA) and Vibrio cholerae haemolysin induce vacuolation. We therefore hypothesise that the serotype C and D botulinum toxin complex is a functional hybrid of the neurotoxin and vacuolating toxin (VT) which arose from horizontal gene transfer from an ancestral BoNT-producing bacterium to a hypothetical VT-producing bacterium.
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Affiliation(s)
- Shin-Ichiro Miyashita
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan
| | - Yoshimasa Sagane
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan
| | - Tomonori Suzuki
- Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | | | - Koichi Niwa
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan
| | - Toshihiro Watanabe
- Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan
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10
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Nishiyama Y, Ohmichi T, Kazami S, Iwasaki H, Mano K, Nagumo Y, Kudo F, Ichikawa S, Iwabuchi Y, Kanoh N, Eguchi T, Osada H, Usui T. Vicenistatin induces early endosome-derived vacuole formation in mammalian cells. Biosci Biotechnol Biochem 2016; 80:902-10. [PMID: 27104762 DOI: 10.1080/09168451.2015.1132152] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Homotypic fusion of early endosomes is important for efficient protein trafficking and sorting. The key controller of this process is Rab5 which regulates several effectors and PtdInsPs levels, but whose mechanisms are largely unknown. Here, we report that vicenistatin, a natural product, enhanced homotypic fusion of early endosomes and induced the formation of large vacuole-like structures in mammalian cells. Unlike YM201636, another early endosome vacuolating compound, vicenistatin did not inhibit PIKfyve activity in vitro but activated Rab5-PAS pathway in cells. Furthermore, vicenistatin increased the membrane surface fluidity of cholesterol-containing liposomes in vitro, and cholesterol deprivation from the plasma membrane stimulated vicenistatin-induced vacuolation in cells. These results suggest that vicenistatin is a novel compound that induces the formation of vacuole-like structures by activating Rab5-PAS pathway and increasing membrane fluidity.
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Affiliation(s)
- Yuko Nishiyama
- a Graduate School of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan
| | - Tomohiro Ohmichi
- a Graduate School of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan
| | - Sayaka Kazami
- b Chemical Biology Research Group, RIKEN CSRS , Wako, Japan
| | - Hiroki Iwasaki
- a Graduate School of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan
| | - Kousuke Mano
- c Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai , Japan
| | - Yoko Nagumo
- a Graduate School of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan
| | - Fumitaka Kudo
- d Graduate School of Science and Engineering , Tokyo Institute of Technology , Tokyo , Japan
| | - Sosaku Ichikawa
- e Faculty of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan
| | - Yoshiharu Iwabuchi
- c Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai , Japan
| | - Naoki Kanoh
- c Graduate School of Pharmaceutical Sciences , Tohoku University , Sendai , Japan
| | - Tadashi Eguchi
- d Graduate School of Science and Engineering , Tokyo Institute of Technology , Tokyo , Japan
| | - Hiroyuki Osada
- b Chemical Biology Research Group, RIKEN CSRS , Wako, Japan
| | - Takeo Usui
- e Faculty of Life and Environmental Sciences , University of Tsukuba , Tsukuba , Japan
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11
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Khilwani B, Chattopadhyay K. Signaling beyond Punching Holes: Modulation of Cellular Responses by Vibrio cholerae Cytolysin. Toxins (Basel) 2015; 7:3344-58. [PMID: 26308054 PMCID: PMC4549754 DOI: 10.3390/toxins7083344] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/12/2015] [Accepted: 08/14/2015] [Indexed: 01/20/2023] Open
Abstract
Pore-forming toxins (PFTs) are a distinct class of membrane-damaging cytolytic proteins that contribute significantly towards the virulence processes employed by various pathogenic bacteria. Vibrio cholerae cytolysin (VCC) is a prominent member of the beta-barrel PFT (beta-PFT) family. It is secreted by most of the pathogenic strains of the intestinal pathogen V. cholerae. Owing to its potent membrane-damaging cell-killing activity, VCC is believed to play critical roles in V. cholerae pathogenesis, particularly in those strains that lack the cholera toxin. Large numbers of studies have explored the mechanistic basis of the cell-killing activity of VCC. Consistent with the beta-PFT mode of action, VCC has been shown to act on the target cells by forming transmembrane oligomeric beta-barrel pores, thereby leading to permeabilization of the target cell membranes. Apart from the pore-formation-induced direct cell-killing action, VCC exhibits the potential to initiate a plethora of signal transduction pathways that may lead to apoptosis, or may act to enhance the cell survival/activation responses, depending on the type of target cells. In this review, we will present a concise view of our current understanding regarding the multiple aspects of these cellular responses, and their underlying signaling mechanisms, evoked by VCC.
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Affiliation(s)
- Barkha Khilwani
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli PO 140306, Punjab, India.
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli PO 140306, Punjab, India.
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12
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Outer membrane vesicles mediate transport of biologically active Vibrio cholerae cytolysin (VCC) from V. cholerae strains. PLoS One 2014; 9:e106731. [PMID: 25187967 PMCID: PMC4154730 DOI: 10.1371/journal.pone.0106731] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 07/28/2014] [Indexed: 12/03/2022] Open
Abstract
Background Outer membrane vesicles (OMVs) released from Gram-negative bacteria can serve as vehicles for the translocation of virulence factors. Vibrio cholerae produce OMVs but their putative role in translocation of effectors involved in pathogenesis has not been well elucidated. The V. cholerae cytolysin (VCC), is a pore-forming toxin that lyses target eukaryotic cells by forming transmembrane oligomeric β-barrel channels. It is considered a potent toxin that contributes to V. cholerae pathogenesis. The mechanisms involved in the secretion and delivery of the VCC have not been extensively studied. Methodology/Principal Findings OMVs from V. cholerae strains were isolated and purified using a differential centrifugation procedure and Optiprep centrifugation. The ultrastructure and the contents of OMVs were examined under the electron microscope and by immunoblot analyses respectively. We demonstrated that VCC from V. cholerae strain V:5/04 was secreted in association with OMVs and the release of VCC via OMVs is a common feature among V. cholerae strains. The biological activity of OMV-associated VCC was investigated using contact hemolytic assay and epithelial cell cytotoxicity test. It showed toxic activity on both red blood cells and epithelial cells. Our results indicate that the OMVs architecture might play a role in stability of VCC and thereby can enhance its biological activities in comparison with the free secreted VCC. Furthermore, we tested the role of OMV-associated VCC in host cell autophagy signalling using confocal microscopy and immunoblot analysis. We observed that OMV-associated VCC triggered an autophagy response in the target cell and our findings demonstrated for the first time that autophagy may operate as a cellular defence mechanism against an OMV-associated bacterial virulence factor. Conclusion/Significance Biological assays of OMVs from the V. cholerae strain V:5/04 demonstrated that OMV-associated VCC is indeed biologically active and induces toxicity on mammalian cells and furthermore can induce autophagy.
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Ikigai H, Otsuru H, Yamamoto K, Shimamura T. Structural Requirements of Cholesterol for Binding toVibrio choleraeHemolysin. Microbiol Immunol 2013; 50:751-7. [PMID: 17053310 DOI: 10.1111/j.1348-0421.2006.tb03848.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cholesterol is necessary for the conversion of Vibrio cholerae hemolysin (VCH) monomers into oligomers in liposome membranes. Using different sterols, we determined the stereochemical structures of the VCH-binding active groups present in cholesterol. The VCH monomers are bound to cholesterol, diosgenin, campesterol, and ergosterol, which have a hydroxyl group at position C-3 (3betaOH) in the A ring and a C-C double bond between positions C-5 and C-6 (C-C Delta(5)) in the B ring. They are not bound to epicholesterol and dihydrocholesterol, which form a covalent link with a 3alphaOH group and a C-C single bond between positions C-5 and C-6, respectively. This result suggests that the 3betaOH group and the C-CDelta(5) bond in cholesterol are required for VCH monomer binding. We further examined VCH oligomer binding to cholesterol. However, this oligomer did not bind to cholesterol, suggesting that the disappearance of the cholesterol-binding potential of the VCH oligomer might be a result of the conformational change caused by the conversion of the monomer into the oligomer. VCH oligomer formation was observed in liposomes containing sterols with the 3betaOH group and the C-C Delta(5) bond, and it correlated with the binding affinity of the monomer to each sterol. Therefore, it seems likely that monomer binding to membrane sterol leads to the assembly of the monomer. However, since oligomer formation was induced by liposomes containing either epicholesterol or dihydrocholesterol, the 3betaOH group and the C-C Delta(5) bond were not essential for conversion into the oligomer.
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Affiliation(s)
- Hajime Ikigai
- Department of Chemistry and Biochemistry, Suzuka National College of Technology, Suzuka, Mie 510-0294, Japan.
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14
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Cinar HN, Kothary M, Datta AR, Tall BD, Sprando R, Bilecen K, Yildiz F, McCardell B. Vibrio cholerae hemolysin is required for lethality, developmental delay, and intestinal vacuolation in Caenorhabditis elegans. PLoS One 2010; 5:e11558. [PMID: 20644623 PMCID: PMC2903476 DOI: 10.1371/journal.pone.0011558] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 06/09/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Cholera toxin (CT) and toxin-co-regulated pili (TCP) are the major virulence factors of Vibrio cholerae O1 and O139 strains that contribute to the pathogenesis of disease during devastating cholera pandemics. However, CT and TCP negative V. cholerae strains are still able to cause severe diarrheal disease in humans through mechanisms that are not well understood. METHODOLOGY/PRINCIPAL FINDINGS To determine the role of other virulence factors in V. cholerae pathogenesis, we used a CT and TCP independent infection model in the nematode Caenorhabditis elegans and identified the hemolysin A (hlyA) gene as a factor responsible for animal death and developmental delay. We demonstrated a correlation between the severity of infection in the nematode and the level of hemolytic activity in the V. cholerae biotypes. At the cellular level, V. cholerae infection induces formation of vacuoles in the intestinal cells in a hlyA dependent manner, consistent with the previous in vitro observations. CONCLUSIONS/SIGNIFICANCE Our data strongly suggest that HlyA is a virulence factor in C. elegans infection leading to lethality and developmental delay presumably through intestinal cytopathic changes.
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Affiliation(s)
- Hediye Nese Cinar
- Division of Virulence Assessment, Food and Drug Administration, Laurel, Maryland, USA.
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15
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Harris JR, Palmer M. Cholesterol specificity of some heptameric beta-barrel pore-forming bacterial toxins: structural and functional aspects. Subcell Biochem 2010; 51:579-596. [PMID: 20213559 DOI: 10.1007/978-90-481-8622-8_21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Apart from the thiol-specific/cholesterol-dependent cytolysin family of toxins (see Chapter 20) there are a number of other unrelated bacterial toxins that also have an affinity for plasma membrane cholesterol. Emphasis is given here on the Vibrio cholerae cytolysin (VCC) and the cytolysins from related Vibrio species. The inhibition of the cytolytic activity of these toxins by prior incubation with extracellular cholesterol or low density lipoprotein emerges as a unifying feature, as does plasma membrane cholesterol depletion. Incubation of VCC with cholesterol produces a heptameric oligomer, which is not equivalent to the pre-pore since it is unable to penetrate the plasma membrane. In structural terms, the precise sequence of VCC monomer binding to membrane, oligomer formation and pore insertion through the bilayer has yet to be fully defined. Several other bacterial toxins have a dependency for cholesterol, although the available data is limited in most cases.
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Affiliation(s)
- J Robin Harris
- Institute of Zoology, University of Mainz, Mainz, D-55099, Germany.
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16
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Debellis L, Diana A, Arcidiacono D, Fiorotto R, Portincasa P, Altomare DF, Spirlì C, de Bernard M. The Vibrio cholerae cytolysin promotes chloride secretion from intact human intestinal mucosa. PLoS One 2009; 4:e5074. [PMID: 19333391 PMCID: PMC2659442 DOI: 10.1371/journal.pone.0005074] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 03/05/2009] [Indexed: 12/02/2022] Open
Abstract
Background The pathogenicity of the Vibrio cholerae strains belonging to serogroup O1 and O139 is due to the production of virulence factors such as cholera toxin (CT) and the toxin-coregulated pilus (TCP). The remaining serogroups, which mostly lack CT and TCP, are more frequently isolated from aquatic environmental sources than from clinical samples; nevertheless, these strains have been reported to cause human disease, such as sporadic outbreaks of watery diarrhoea and inflammatory enterocolitis. This evidence suggested the possibility that other virulence factor(s) than cholera toxin might be crucial in the pathogenesis of Vibrio cholerae-induced diarrhoea, but their nature remains unknown. VCC, the hemolysin produced by virtually all Vibrio cholerae strains, has been proposed as a possible candidate, though a clear-cut demonstration attesting VCC as crucial in the pathogenesis of Vibrio cholerae-induced diarrhoea is still lacking. Methodology/Principal Findings Electrophysiological parameters and paracellular permeability of stripped human healthy colon tissues, obtained at subtotal colectomy, mounted in Ussing chamber were studied in the presence or absence of VCC purified from culture supernatants of V. cholerae O1 El Tor strain. Short circuit current (ISC) and transepithelial resistance (RT) were measured by a computerized voltage clamp system. The exposure of sigmoid colon specimens to 1 nM VCC resulted in an increase of ISC by 20.7%, with respect to the basal values, while RT was reduced by 12.3%. Moreover, increase in ISC was abolished by bilateral Cl− reduction. Conclusion/Significance Our results demonstrate that VCC, by forming anion channels on the apical membrane of enterocytes, triggers an outward transcellular flux of chloride. Such an ion movement, associated with the outward movement of Na+ and water, might be responsible for the diarrhoea caused by the non-toxigenic strains of Vibrio cholerae.
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Affiliation(s)
- Lucantonio Debellis
- Department of General and Environmental Physiology, University of Bari, Bari, Italy
| | - Anna Diana
- Department of General and Environmental Physiology, University of Bari, Bari, Italy
| | | | - Romina Fiorotto
- Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut, United States of America
| | - Piero Portincasa
- Clinica Medica “A. Murri”, Department of Internal and Public Medicine, University Medical School, Bari, Italy
| | - Donato Francesco Altomare
- Department of Emergency and Organ Transplantation, General Surgery and Liver Transplantation Units, University of Bari, Policlinico, Bari, Italy
| | - Carlo Spirlì
- Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut, United States of America
| | - Marina de Bernard
- Venetian Institute of Molecular Medicine, Padua, Italy
- Department of Biology, University of Padua, Padua, Italy
- * E-mail:
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17
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Vibrio cholerae cytolysin is essential for high enterotoxicity and apoptosis induction produced by a cholera toxin gene-negative V. cholerae non-O1, non-O139 strain. Microb Pathog 2008; 44:118-28. [DOI: 10.1016/j.micpath.2007.08.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Accepted: 08/10/2007] [Indexed: 12/21/2022]
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18
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Arcidiacono D, Odom S, Frossi B, Rivera J, Paccani SR, Baldari CT, Pucillo C, Montecucco C, de Bernard M. The Vibrio cholerae cytolysin promotes activation of mast cell (T helper 2) cytokine production. Cell Microbiol 2007; 10:899-907. [PMID: 18005391 DOI: 10.1111/j.1462-5822.2007.01092.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Many strains of Vibrio cholerae produce a cytolysin (VCC) that forms oligomeric transmembrane pores responsible for vacuolization of several cell types in culture. Here we suggest that VCC could contribute to the T helper 2 (Th2) response seen in the natural infection; acting through TLR2, VCC enhances mast cells secretion of IL-4, IL-6 and TNF-alpha by 330-, 290- and 550-fold respectively. Moreover, VCC-induced cytokine production is dependent on increased cytosolic Ca(2+) and on the presence of the Src family kinases Lyn and Fyn, known to be required for FcepsilonRI-dependent activation of mast cells. These findings strongly suggest that VCC has a pro-inflammatory activity promoting a Th2-type immune profile.
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Affiliation(s)
- Diletta Arcidiacono
- Department of Biomedical Sciences, University of Padua, Via G. Colombo 3, 35121 Padua, Italy
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19
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Valeva A, Walev I, Weis S, Boukhallouk F, Wassenaar TM, Bhakdi S. Pro-inflammatory feedback activation cycle evoked by attack of Vibrio cholerae cytolysin on human neutrophil granulocytes. Med Microbiol Immunol 2007; 197:285-93. [PMID: 17882454 DOI: 10.1007/s00430-007-0061-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Indexed: 11/28/2022]
Abstract
Vibrio cholerae cytolysin (VCC) is a pore-forming toxin that is secreted in precursor form (pro-VCC) and requires proteolytic cleavage in order to attain membrane-permeabilizing properties. Pro-VCC can be activated both in solution and membrane-bound state. Processing of membrane-bound pro-VCC can in turn be achieved through the action of both cell-associated and soluble proteases. The current investigation describes the interaction of VCC with human neutrophil granulocytes. It is shown that pro-VCC binds to these cells and is cleaved by cell-bound serine proteases. Membrane permeabilization leads to granulocyte activation, as witnessed by the generation of reactive oxygen metabolites and liberation of granule constituents. A mutant toxin with unaltered binding properties but devoid of pore-forming activity did not elicit these effects. The secreted proteases cleave and activate further bound- and non-bound pro-VCC. A positive feedback loop is thus created that results in enhanced cytotoxicity towards both the targeted granulocytes and towards bystander cells that are not primarily killed by the protoxin. Thus, activation of neutrophil granulocytes by VCC fuels a positive feedback cycle that will cripple immune defence, augment inflammation, and enhance the cytotoxic action of the toxin on neighbouring tissue cells.
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Affiliation(s)
- Angela Valeva
- Institute of Medical Microbiology and Hygiene, University of Mainz, Augustusplatz, Mainz, Germany.
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20
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Gutierrez MG, Saka HA, Chinen I, Zoppino FCM, Yoshimori T, Bocco JL, Colombo MI. Protective role of autophagy against Vibrio cholerae cytolysin, a pore-forming toxin from V. cholerae. Proc Natl Acad Sci U S A 2007; 104:1829-34. [PMID: 17267617 PMCID: PMC1794277 DOI: 10.1073/pnas.0601437104] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Autophagy is the unique, regulated mechanism for the degradation of organelles. This intracellular process acts as a prosurvival pathway during cell starvation or stress and is also involved in cellular response against specific bacterial infections. Vibrio cholerae is a noninvasive intestinal pathogen that has been studied extensively as the causative agent of the human disease cholera. V. cholerae illness is produced primarily through the expression of a potent toxin (cholera toxin) within the human intestine. Besides cholera toxin, this bacterium secretes a hemolytic exotoxin termed V. cholerae cytolysin (VCC) that causes extensive vacuolation in epithelial cells. In this work, we explored the relationship between the vacuolation caused by VCC and the autophagic pathway. Treatment of cells with VCC increased the punctate distribution of LC3, a feature indicative of autophagosome formation. Moreover, VCC-induced vacuoles colocalized with LC3 in several cell lines, including human intestinal Caco-2 cells, indicating the interaction of the large vacuoles with autophagic vesicles. Electron microscopy analysis confirmed that the vacuoles caused by VCC presented hallmarks of autophagosomes. Additionally, biochemical evidence demonstrated the degradative nature of the VCC-generated vacuoles. Interestingly, autophagy inhibition resulted in decreased survival of Caco-2 cells upon VCC intoxication. Also, VCC failed to induce vacuolization in Atg5-/- cells, and the survival response of these cells against the toxin was dramatically impaired. These results demonstrate that autophagy acts as a cellular defense pathway against secreted bacterial toxins.
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Affiliation(s)
- Maximiliano Gabriel Gutierrez
- *Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
| | - Hector Alex Saka
- Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología–CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina
| | - Isabel Chinen
- Servicio de Fisiopatogenia, Instituto Nacional de Enfermedades Infecciosas, Administración Nacional de Laboratorios e Institutos de Salud “Dr. Carlos G. Malbrán,” 1281 Buenos Aires, Argentina; and
| | - Felipe C. M. Zoppino
- *Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
| | - Tamotsu Yoshimori
- Department of Cell Genetics, National Institute of Genetics, Yata 1111 Mishima, Shizuoka 455-8540, Japan
| | - Jose Luis Bocco
- Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología–CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina
- To whom correspondence may be addressed. E-mail:
or
| | - María Isabel Colombo
- *Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
- To whom correspondence may be addressed. E-mail:
or
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21
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Genisset C, Puhar A, Calore F, de Bernard M, Dell'Antone P, Montecucco C. The concerted action of the Helicobacter pylori cytotoxin VacA and of the v-ATPase proton pump induces swelling of isolated endosomes. Cell Microbiol 2007; 9:1481-90. [PMID: 17253977 DOI: 10.1111/j.1462-5822.2006.00886.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The vacuolating cytotoxin (VacA) is a major virulence factor of Helicobacter pylori, the bacterium associated to gastroduodenal ulcers and stomach cancers. VacA induces formation of cellular vacuoles that originate from late endosomal compartments. VacA forms an anion-selective channel and its activity has been suggested to increase the osmotic pressure in the lumen of these acidic compartments, driving their swelling to vacuoles. Here, we have tested this proposal on isolated endosomes that allow one to manipulate at will the medium. We have found that VacA enhances the v-ATPase proton pump activity and the acidification of isolated endosomes in a Cl- dependent manner. Other counter-anions such as pyruvate, Br-, I- and SCN- can be transported by VacA with stimulation of the v-ATPase. The VacA action on isolated endosomes is associated with their increase in size. Single amino acid substituted VacA with no channel-forming and vacuolating activity is unable to induce swelling of endosomes. These data provide a direct evidence that the transmembrane VacA channel mediates an influx of anions into endosomes that stimulates the electrogenic v-ATPase proton pump, leading to their osmotic swelling and transformation into vacuoles.
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Affiliation(s)
- Christophe Genisset
- Dipartimento di Scienze Biomediche Sperimentali, Università di Padova, Padova, Italy
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22
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Pantano S, Montecucco C. A molecular model of the Vibrio cholerae cytolysin transmembrane pore. Toxicon 2005; 47:35-40. [PMID: 16330061 DOI: 10.1016/j.toxicon.2005.09.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Revised: 08/31/2005] [Accepted: 09/22/2005] [Indexed: 01/05/2023]
Abstract
The cytotoxic activity of some of the most pathogenic strains of Vibrio cholerae is associated with a cytolysin protein (VCC), which forms oligomeric transmembrane pores and changes the permeability of intestinal cells. We present here a model structure of the transmembrane pore of VCC based on sequence comparison with other pore-forming toxins. VCC is suggested to form a transmembrane beta-barrel pore with a relatively large trans vestibule region. Calculations of the electrostatic profile within the pore lumen provide a rationale for the low conductance and selectivity of the VCC ion channel.
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Affiliation(s)
- Sergio Pantano
- Venetian Institute of Molecular Medicine (VIMM),Via Orus 2, 35129, Padova, Italy.
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23
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Huffman DL, Bischof LJ, Griffitts JS, Aroian RV. Pore worms: using Caenorhabditis elegans to study how bacterial toxins interact with their target host. Int J Med Microbiol 2004; 293:599-607. [PMID: 15149037 DOI: 10.1078/1438-4221-00303] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The interaction of pathogenic bacteria with a target host is regulated both by bacterial virulence factors and by host components that either protect the host or that promote pathogenesis. The soil nematode Caenorhabditis elegans is a host for a number of bacterial pathogens, as briefly reviewed here. Bacillus thuringiensis (Bt) is a pathogenic bacteria that C. elegans is likely to encounter naturally in the soil. The pore-forming Crystal (Cry) toxins made by Bt are recognized as the dominant virulence factor in this host-pathogen interaction. Forward genetic screens for C. elegans mutants resistant to the Cry toxin, Cry5B, have identified a host carbohydrate structure that promotes pathogenesis. Data suggest this structure is likely to be a Cry5B receptor expressed in the host intestine. This finding is discussed in light of other carbohydrate receptors for bacterial toxins. To investigate host-toxin interactions on a global level, the response of C. elegans to the pore-forming Cry5B is also being investigated by gene transcription profiling (microarrays). These data are beginning to reveal a diverse intracellular response to toxin exposure. To put these investigations in perspective, host responses to other pore-forming toxins are discussed. Investigations with Cry5B in C. elegans show a promising beginning in helping to elucidate host-toxin and host-pathogen interactions.
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Affiliation(s)
- Danielle L Huffman
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0349, USA
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24
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de Bernard M, Cappon A, Del Giudice G, Rappuoli R, Montecucco C. The multiple cellular activities of the VacA cytotoxin of Helicobacter pylori. Int J Med Microbiol 2004; 293:589-97. [PMID: 15149036 DOI: 10.1078/1438-4221-00299] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Helicobacter pylori has elaborated a unique set of virulence factors that allow it to colonize the stomach wall. These factors include urease, helicoidal shape, flagella, adhesion and pro-inflammatory molecules. Here we discuss the molecular and cellular mechanisms of action of the vacuolating cytotoxin VacA. Its activities are discussed in terms of tissue alterations which promote the release of nutrients necessary to the growth and survival of the bacterium in its nutrient-poor ecological niche. This toxin also shows some pro-inflammatory and immunosuppressive activities which may be functional to the establishment of a chronic type of inflammation.
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Affiliation(s)
- Marina de Bernard
- Dipartimento di Scienze Biomediche, Università di Padova, Istituto Veneto di Medicina Molecolare, Padova, Italy
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25
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Valeva A, Walev I, Weis S, Boukhallouk F, Wassenaar TM, Endres K, Fahrenholz F, Bhakdi S, Zitzer A. A cellular metalloproteinase activates Vibrio cholerae pro-cytolysin. J Biol Chem 2004; 279:25143-8. [PMID: 15066987 DOI: 10.1074/jbc.m313913200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many strains of Vibrio cholerae produce a cytolysin (VCC) that forms oligomeric transmembrane pores in animal cells. The molecule is secreted as a procytolysin (pro-VCC) of 79 kDa that must be cleaved at the N terminus to generate the active 65-kDa toxin. Processing can occur in solution, and previous studies have described the action of mature VCC thus generated. However, little is known about the properties of pro-VCC itself. In this study, it is shown that pro-VCC exist as a monomer in solution and binds as a monomer to eukaryotic cells. Bound pro-VCC can then be activated either by exogenous, extracellular, or by endogenous, cell-bound proteases. In both cases, cleavage generates the 65-kDa VCC that oligomerizes to form transmembrane pores. A wide variety of exogenous proteinases can mediate activation. In contrast, the activating cellular protease is selectively inhibited by the hydroxamate inhibitor TAPI, and thus probable candidates are members of the ADAM-metalloproteinase family. Furin, MMP-2, MMP-9, and serine proteinases were excluded. Cells over-expressing ADAM-17, also known as tumor necrosis factor alpha converting enzyme, displayed increased activation of VCC, and knockout cells lacking ADAM-17 had a markedly decreased capacity to cleave the protoxin. The possibility is raised that pro-VCC is targeted to membrane sites that selectively contain or are accessible to cellular ADAM-metalloproteinases. Although many microbial toxins are activated by furin, this is the first evidence for processing by a cellular metalloproteinase. We identified ADAM-17 as a potent activator of pro-VCC.
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Affiliation(s)
- Angela Valeva
- Institute of Medical Microbiology and Hygiene, University of Mainz, D55101 Mainz, Germany.
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26
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Torres VJ, McClain MS, Cover TL. Interactions between p-33 and p-55 domains of the Helicobacter pylori vacuolating cytotoxin (VacA). J Biol Chem 2003; 279:2324-31. [PMID: 14593124 DOI: 10.1074/jbc.m310159200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The VacA toxin secreted by Helicobacter pylori is considered to be an important virulence factor in the pathogenesis of peptic ulcer disease and gastric cancer. VacA monomers self-assemble into water-soluble oligomeric structures and can form anion-selective membrane channels. The goal of this study was to characterize VacA-VacA interactions that may mediate assembly of VacA monomers into higher order structures. We investigated potential interactions between two domains of VacA (termed p-33 and p-55) by using a yeast two-hybrid system. p-33/p-55 interactions were detected in this system, whereas p-33/p-33 and p-55/p-55 interactions were not detected. Several p-33 proteins containing internal deletion mutations were unable to interact with wild-type p-55 in the yeast two-hybrid system. Introduction of these same deletion mutations into the H. pylori vacA gene resulted in secretion of mutant VacA proteins that failed to assemble into large oligomeric structures and that lacked vacuolating toxic activity for HeLa cells. Additional mapping studies in the yeast two-hybrid system indicated that only the N-terminal portion of the p-55 domain is required for p-33/p-55 interactions. To characterize further p-33/p-55 interactions, we engineered an H. pylori strain that produced a VacA toxin containing an enterokinase cleavage site located between the p-33 and p-55 domains. Enterokinase treatment resulted in complete proteolysis of VacA into p-33 and p-55 domains, which remained physically associated within oligomeric structures and retained vacuolating cytotoxin activity. These results provide evidence that interactions between p-33 and p-55 domains play an important role in VacA assembly into oligomeric structures.
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Affiliation(s)
- Victor J Torres
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2605, USA
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