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Saberi S, Shans N, Ghaffari S, Esmaeili M, Mohammadi M. The role of CEACAMs versus integrins in Helicobacter pylori CagA translocation: a systematic review. Microbes Infect 2024; 26:105246. [PMID: 37926369 DOI: 10.1016/j.micinf.2023.105246] [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: 03/04/2023] [Revised: 10/24/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
The delivery of Helicobacter pylori CagA into host cells was long believed to occur through the integrin cell surface receptors. However, the role of CEACAM receptors has recently been highlighted, instead. Here, we have categorized the existing experimental evidence according to whether deletion, upregulation, downregulation, or inhibition of the target ligands (T4SS or HopQ) or receptors (integrins or CEACAMs), result in alterations in CagA phosphorylation, cell elongation, or IL-8 production. According to our analysis, the statistics favor the essence of most of the T4SS constituents and the involvement of HopQ adhesin in all three functions. Concerning the integrin family, the collected data is controversial, but yielding towards it being dispensable or involved in CagA translocation. Yet, regarding cell elongation, more events are showing β1 integrin being involved, than αvβ4 being inhibitory. Concerning IL-8 secretion, again there are more events showing α5, β1 and β6 integrins to be involved, than those showing inhibitory roles for β1, β4 and β6 integrins. Finally, CEACAM 1, 3, and 5 are identified as mostly essential or involved in CagA phosphorylation, whereasCEACAM 4, 7, and 8 are found dispensable and CEACAM6 is under debate. Conversely, CEACAM1, 5 and 6 appear mostly dispensable for cell elongation. Noteworthy is the choice of cell type, bacterial strain, multiplicity and duration of infection, as well as the sensitivity of the detection methods, all of which can affect the variably obtained results.
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Affiliation(s)
- Samaneh Saberi
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Nazanin Shans
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Saba Ghaffari
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Maryam Esmaeili
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Marjan Mohammadi
- HPGC Research Group, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
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2
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Tran SC, Bryant KN, Cover TL. The Helicobacter pylori cag pathogenicity island as a determinant of gastric cancer risk. Gut Microbes 2024; 16:2314201. [PMID: 38391242 PMCID: PMC10896142 DOI: 10.1080/19490976.2024.2314201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 01/31/2024] [Indexed: 02/24/2024] Open
Abstract
Helicobacter pylori strains can be broadly classified into two groups based on whether they contain or lack a chromosomal region known as the cag pathogenicity island (cag PAI). Colonization of the human stomach with cag PAI-positive strains is associated with an increased risk of gastric cancer and peptic ulcer disease, compared to colonization with cag PAI-negative strains. The cag PAI encodes a secreted effector protein (CagA) and components of a type IV secretion system (Cag T4SS) that delivers CagA and non-protein substrates into host cells. Animal model experiments indicate that CagA and the Cag T4SS stimulate a gastric mucosal inflammatory response and contribute to the development of gastric cancer. In this review, we discuss recent studies defining structural and functional features of CagA and the Cag T4SS and mechanisms by which H. pylori strains containing the cag PAI promote the development of gastric cancer and peptic ulcer disease.
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Affiliation(s)
- Sirena C Tran
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kaeli N Bryant
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Timothy L Cover
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
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3
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Mechanism of regulation of the Helicobacter pylori Cagβ ATPase by CagZ. Nat Commun 2023; 14:479. [PMID: 36717564 PMCID: PMC9886983 DOI: 10.1038/s41467-023-36218-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/20/2023] [Indexed: 02/01/2023] Open
Abstract
The transport of the CagA effector into gastric epithelial cells by the Cag Type IV secretion system (Cag T4SS) of Helicobacter pylori (H. pylori) is critical for pathogenesis. CagA is recruited to Cag T4SS by the Cagβ ATPase. CagZ, a unique protein in H. pylori, regulates Cagβ-mediated CagA transport, but the underlying mechanisms remain unclear. Here we report the crystal structure of the cytosolic region of Cagβ, showing a typical ring-like hexameric assembly. The central channel of the ring is narrow, suggesting that CagA must unfold for transport through the channel. Our structure of CagZ in complex with the all-alpha domain (AAD) of Cagβ shows that CagZ adopts an overall U-shape and tightly embraces Cagβ. This binding mode of CagZ is incompatible with the formation of the Cagβ hexamer essential for the ATPase activity. CagZ therefore inhibits Cagβ by trapping it in the monomeric state. Based on these findings, we propose a refined model for the transport of CagA by Cagβ.
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4
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Freire de Melo F, Marques HS, Rocha Pinheiro SL, Lemos FFB, Silva Luz M, Nayara Teixeira K, Souza CL, Oliveira MV. Influence of Helicobacter pylori oncoprotein CagA in gastric cancer: A critical-reflective analysis. World J Clin Oncol 2022; 13:866-879. [PMID: 36483973 PMCID: PMC9724182 DOI: 10.5306/wjco.v13.i11.866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 09/20/2022] [Accepted: 10/11/2022] [Indexed: 11/21/2022] Open
Abstract
Gastric cancer is the fifth most common malignancy and third leading cancer-related cause of death worldwide. Helicobacter pylori is a Gram-negative bacterium that inhabits the gastric environment of 60.3% of the world’s population and represents the main risk factor for the onset of gastric neoplasms. CagA is the most important virulence factor in H. pylori, and is a translocated oncoprotein that induces morphofunctional modifications in gastric epithelial cells and a chronic inflammatory response that increases the risk of developing precancerous lesions. Upon translocation and tyrosine phosphorylation, CagA moves to the cell membrane and acts as a pathological scaffold protein that simultaneously interacts with multiple intracellular signaling pathways, thereby disrupting cell proliferation, differentiation and apoptosis. All these alterations in cell biology increase the risk of damaged cells acquiring pro-oncogenic genetic changes. In this sense, once gastric cancer sets in, its perpetuation is independent of the presence of the oncoprotein, characterizing a “hit-and-run” carcinogenic mechanism. Therefore, this review aims to describe H. pylori- and CagA-related oncogenic mechanisms, to update readers and discuss the novelties and perspectives in this field.
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Affiliation(s)
- Fabrício Freire de Melo
- Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista 45029-094, Brazil
| | - Hanna Santos Marques
- Campus Vitória da Conquista, Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista 45029-094, Brazil
| | - Samuel Luca Rocha Pinheiro
- Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista 45029-094, Brazil
| | - Fabian Fellipe Bueno Lemos
- Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista 45029-094, Brazil
| | - Marcel Silva Luz
- Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista 45029-094, Brazil
| | | | - Cláudio Lima Souza
- Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista 45029-094, Brazil
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5
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Jaboulay C, Godeux AS, Doublet P, Vianney A. Regulatory Networks of the T4SS Control: From Host Cell Sensing to the Biogenesis and the Activity during the Infection. J Mol Biol 2021; 433:166892. [PMID: 33636165 DOI: 10.1016/j.jmb.2021.166892] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 02/03/2023]
Abstract
Delivery of effectors, DNA or proteins, that hijack host cell processes to the benefit of bacteria is a mechanism widely used by bacterial pathogens. It is achieved by complex effector injection devices, the secretion systems, among which Type 4 Secretion Systems (T4SSs) play a key role in bacterial virulence of numerous animal and plant pathogens. Considerable progress has recently been made in the structure-function analyses of T4SSs. Nevertheless, the signals and processes that trigger machine assembly and activity during infection, as well as those involved in substrate recognition and transfer, are complex and still poorly understood. In this review, we aim at summarizing the last updates of the knowledge on signaling pathways that regulate the biogenesis and the activity of T4SSs in important bacterial pathogens.
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Affiliation(s)
- C Jaboulay
- CIRI, Centre International de Recherche en Infectiologie, (Team: Legionella pathogenesis), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France.
| | - A S Godeux
- CIRI, Centre International de Recherche en Infectiologie, (Team: Horigene), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
| | - P Doublet
- CIRI, Centre International de Recherche en Infectiologie, (Team: Legionella pathogenesis), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
| | - A Vianney
- CIRI, Centre International de Recherche en Infectiologie, (Team: Legionella pathogenesis), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
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6
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Lu Y, Pang J, Wang G, Hu X, Li X, Li G, Wang X, Yang X, Li C, You X. Quantitative proteomics approach to investigate the antibacterial response of Helicobacter pylori to daphnetin, a traditional Chinese medicine monomer. RSC Adv 2021; 11:2185-2193. [PMID: 35424199 PMCID: PMC8693750 DOI: 10.1039/d0ra06677j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 12/11/2020] [Indexed: 12/20/2022] Open
Abstract
Helicobacter pylori is a Gram-negative bacterium related to the development of peptic ulcers and stomach cancer. An increasing number of infected individuals are found to harbor antibiotic-resistant H. pylori, which results in treatment failure. Daphnetin, a traditional Chinese medicine, has a broad spectrum of antibacterial activity without the development of bacterial resistance. However, the antibacterial mechanisms of daphnetin have not been elucidated entirely. To better understand the mechanisms of daphnetin's effect on H. pylori, a label-free quantitative proteomics approach based on an EASY-nLC 1200 system coupled with an Orbitrap Fusion Lumos mass spectrometer was established to investigate the key protein differences between daphnetin- and non-daphnetin-treated H. pylori. Using the criteria of greater than 1.5-fold changes and adjusted p value <0.05, proteins related to metabolism, membrane structure, nucleic acid and protein synthesis, ion binding, H. pylori colonization and infection, stress reaction, flagellar assembly and so on were found to be changed under daphnetin pressure. And the changes of selected proteins in expression level were confirmed by targeted proteomics. These new data provide us a more comprehensive horizon of the proteome changes in H. pylori that occur in response to daphnetin.
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Affiliation(s)
- Yun Lu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Jing Pang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Genzhu Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xinxin Hu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xue Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Guoqing Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xiukun Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xinyi Yang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Congran Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
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7
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The Helicobacter pylori Cag Type IV Secretion System. Trends Microbiol 2020; 28:682-695. [PMID: 32451226 DOI: 10.1016/j.tim.2020.02.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 01/30/2020] [Accepted: 02/25/2020] [Indexed: 12/24/2022]
Abstract
Colonization of the human stomach with Helicobacter pylori strains containing the cag pathogenicity island is a risk factor for development of gastric cancer. The cag pathogenicity island contains genes encoding a secreted effector protein (CagA) and components of a type IV secretion system (Cag T4SS). The molecular architecture of the H. pylori Cag T4SS is substantially more complex than that of prototype T4SSs in other bacterial species. In this review, we discuss recent discoveries pertaining to the structure and function of the Cag T4SS and its role in gastric cancer pathogenesis.
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8
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Zeng B, Chen C, Yi Q, Zhang X, Wu X, Zheng S, Li N, She F. N-terminal region of Helicobacter pylori CagA induces IL-8 production in gastric epithelial cells via the β1 integrin receptor. J Med Microbiol 2020; 69:457-464. [DOI: 10.1099/jmm.0.001088] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Introduction.
Helicobacter pylori
is associated with gastrointestinal disease, most notably gastric cancer. Cytotoxin-associated antigen A (CagA), an important virulence factor for
H. pylori
pathogenicity, induces host cells to release inflammatory factors, especially interleukin-8 (IL-8). The mechanism by which C-terminal CagA induces IL-8 production has been studied extensively, but little is known about the role of the N-terminus.
Aim. To investigate the effect of CagA303–456aa (a peptide in the N-terminal CagA) on IL-8 production by gastric epithelial cells.
Methodology. CagA303-456aa was produced by a prokaryotic expression system and purified by Strep-tag affinity chromatography. An integrin β1 (ITGB1)-deficient AGS cell line was constructed using the CRISPR/Cas9 technique, and NCTC 11637 cagA and/or cagL knockout mutants were constructed via homologous recombination. The levels of IL-8 production were determined by enzyme-linked immunosorbent assay (ELISA), and p38 and ERK1/2 phosphorylation were examined by Western blot.
Results. CagA303-456aa induced IL-8 expression by AGS cells. IL-8 induction by CagA303-456aawas specifically inhibited by ITGB1 deficiency. Notably, CagA303-456aa activated the phosphorylation of both p38 and ERK1/2, and blocking p38 and ERK1/2 activity significantly reduced IL-8 induction by CagA303-456aa. ITGB1 deficiency also inhibited the activation of p38 phosphorylation by CagA303-456aa. Finally, experiments in CagA and/or CagL knockout bacterial lines demonstrated that extracellular CagA might induce IL-8 production by AGS cells.
Conclusion. Residues 303–456 of the N-terminal region of CagA induce IL-8 production via a CagA303-456–ITGB1–p38–IL-8 pathway, and ERK1/2 is also involved in the release of IL-8. Extracellular CagA might induce IL-8 production before translocation into AGS cells.
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Affiliation(s)
- Bangwei Zeng
- Fujian Medical University Union Hospital, 29 Xinquan Road, Fuzhou, Fujian Province 350001, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Chu Chen
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Qingfeng Yi
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Xiaoyan Zhang
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Xiangyan Wu
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Shurong Zheng
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Neng Li
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
| | - Feifei She
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
- Fujian Key Laboratory of Tumor Microbiology, School of Basic Medical Sciences, Fujian Medical University, 1 Xuefu North Road, University Town, Fuzhou, Fujian Province 350122, PR China
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9
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Molecular anatomy and pathogenic actions of Helicobacter pylori CagA that underpin gastric carcinogenesis. Cell Mol Immunol 2019; 17:50-63. [PMID: 31804619 PMCID: PMC6952403 DOI: 10.1038/s41423-019-0339-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/13/2019] [Accepted: 11/13/2019] [Indexed: 12/15/2022] Open
Abstract
Chronic infection with Helicobacter pylori cagA-positive strains is the strongest risk factor for gastric cancer. The cagA gene product, CagA, is delivered into gastric epithelial cells via the bacterial type IV secretion system. Delivered CagA then undergoes tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs in its C-terminal region and acts as an oncogenic scaffold protein that physically interacts with multiple host signaling proteins in both tyrosine phosphorylation-dependent and -independent manners. Analysis of CagA using in vitro cultured gastric epithelial cells has indicated that the nonphysiological scaffolding actions of CagA cell-autonomously promote the malignant transformation of the cells by endowing the cells with multiple phenotypic cancer hallmarks: sustained proliferation, evasion of growth suppressors, invasiveness, resistance to cell death, and genomic instability. Transgenic expression of CagA in mice leads to in vivo oncogenic action of CagA without any overt inflammation. The in vivo oncogenic activity of CagA is further potentiated in the presence of chronic inflammation. Since Helicobacter pylori infection triggers a proinflammatory response in host cells, a feedforward stimulation loop that augments the oncogenic actions of CagA and inflammation is created in CagA-injected gastric mucosa. Given that Helicobacter pylori is no longer colonized in established gastric cancer lesions, the multistep nature of gastric cancer development should include a “hit-and-run” process of CagA action. Thus, acquisition of genetic and epigenetic alterations that compensate for CagA-directed cancer hallmarks may be required for completion of the “hit-and-run” process of gastric carcinogenesis.
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10
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Kumari R, Shariq M, Sharma S, Kumar A, Mukhopadhyay G. CagW, a VirB6 homologue interacts with Cag-type IV secretion system substrate CagA in Helicobacter pylori. Biochem Biophys Res Commun 2019; 515:712-718. [PMID: 31182283 DOI: 10.1016/j.bbrc.2019.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 06/03/2019] [Indexed: 01/19/2023]
Abstract
Protein translocating Cag type IV secretion system of Helicobacter pylori is a diverse multi-protein complex. Here, we have characterized one of its key subunit CagW to identify its interacting partners. Our results demonstrate for the first time that this VirB6 homologue interacts with the substrate of the secretion system CagA. CagW forms multimer and its absence affects cellular levels of pilus forming components, CagL, CagI and CagH. Our results support the notion that the protein is essential for the transport of CagA across the bacterial membrane barrier and would aid in improving our understanding of structural and functional aspects of the inner membrane part of Cag-T4SS channel complex for the passage of substrate CagA.
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Affiliation(s)
- Rajesh Kumari
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Mohd Shariq
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Shivani Sharma
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Ajay Kumar
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Gauranga Mukhopadhyay
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India.
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11
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Abstract
Type IV secretion systems (T4SSs) are nanomachines that Gram-negative, Gram-positive bacteria, and some archaea use to transport macromolecules across their membranes into bacterial or eukaryotic host targets or into the extracellular milieu. They are the most versatile secretion systems, being able to deliver both proteins and nucleoprotein complexes into targeted cells. By mediating conjugation and/or competence, T4SSs play important roles in determining bacterial genome plasticity and diversity; they also play a pivotal role in the spread of antibiotic resistance within bacterial populations. T4SSs are also used by human pathogens such as Legionella pneumophila, Bordetella pertussis, Brucella sp., or Helicobacter pylori to sustain infection. Since they are essential virulence factors for these important pathogens, T4SSs might represent attractive targets for vaccines and therapeutics. The best-characterized conjugative T4SSs of Gram-negative bacteria are composed of twelve components that are conserved across many T4SSs. In this chapter, we will review our current structural knowledge on the T4SSs by describing the structures of the individual components and how they assemble into large macromolecular assemblies. With the combined efforts of X-ray crystallography, nuclear magnetic resonance (NMR), and more recently electron microscopy, structural biology of the T4SS has made spectacular progress during the past fifteen years and has unraveled the properties of unique proteins and complexes that assemble dynamically in a highly sophisticated manner.
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12
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Yuan XY, Wang Y, Wang MY. The type IV secretion system in Helicobacter pylori. Future Microbiol 2018; 13:1041-1054. [PMID: 29927340 DOI: 10.2217/fmb-2018-0038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Helicobacter pylori (H. pylori) has an essential role in the pathogenesis of gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma and gastric cancer. The severity of the host inflammatory responses against the bacteria have been straightly associated with a special bacterial virulence factor, the cag pathogenicity island, which is a type IV secretion system (T4SS) to deliver CagA into the host cells. Besides cag-T4SS, the chromosomes of H. pylori can encode another three T4SSs, including comB, tfs3 and tfs4. In this review, we systematically reviewed the four T4SSs of H. pylori and explored their roles in the pathogenesis of gastroduodenal diseases. The information summarized in this review might provide valuable insights into the pathogenic mechanism for H. pylori.
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Affiliation(s)
- Xiao-Yan Yuan
- Department of Central Lab, Weihai Municipal Hospital Affiliated to Dalian Medical University, Weihai, Shandong, 264200, PR China
| | - Ying Wang
- Department of Central Lab, Weihai Municipal Hospital Affiliated to Dalian Medical University, Weihai, Shandong, 264200, PR China
| | - Ming-Yi Wang
- Department of Central Lab, Weihai Municipal Hospital Affiliated to Dalian Medical University, Weihai, Shandong, 264200, PR China
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13
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Koelblen T, Bergé C, Cherrier MV, Brillet K, Jimenez-Soto L, Ballut L, Takagi J, Montserret R, Rousselle P, Fischer W, Haas R, Fronzes R, Terradot L. Molecular dissection of protein-protein interactions between integrin α5β1 and the Helicobacter pylori
Cag type IV secretion system. FEBS J 2017; 284:4143-4157. [DOI: 10.1111/febs.14299] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/04/2017] [Accepted: 10/17/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Thomas Koelblen
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Célia Bergé
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Mickaël V. Cherrier
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Karl Brillet
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Luisa Jimenez-Soto
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie; Ludwig-Maximilians-Universität; München Germany
| | - Lionel Ballut
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Junichi Takagi
- Laboratory of Protein Synthesis and Expression; Institute for Protein Research; Osaka University; Japan
| | - Roland Montserret
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Patricia Rousselle
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique; UMR 5305; CNRS; University Lyon 1; France
| | - Wolfgang Fischer
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie; Ludwig-Maximilians-Universität; München Germany
| | - Rainer Haas
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie; Ludwig-Maximilians-Universität; München Germany
- German Center for Infection Research (DZIF); Partner Site LMU; München Germany
| | - Rémi Fronzes
- European Institute of Chemistry and Biology; CNRS; UMR 5234; Microbiologie Fondamentale et Pathogénicité; University of Bordeaux; Pessac France
| | - Laurent Terradot
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
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14
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Structural Insights into Helicobacter pylori Cag Protein Interactions with Host Cell Factors. Curr Top Microbiol Immunol 2017; 400:129-147. [PMID: 28124152 DOI: 10.1007/978-3-319-50520-6_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The most virulent strains of Helicobacter pylori carry a genomic island (cagPAI) containing a set of 27-31 genes. The encoded proteins assemble a syringe-like apparatus to inject the cytotoxin-associated gene A (CagA) protein into gastric cells. This molecular device belongs to the type IV secretion system (T4SS) family albeit with unique characteristics. The cagPAI-encoded T4SS and its effector protein CagA have an intricate relationship with the host cell, with multiple interactions that only start to be deciphered from a structural point of view. On the one hand, the major roles of the interactions between CagL and CagA (and perhaps CagI and CagY) and host cell factors are to facilitate H. pylori adhesion and to mediate the injection of the CagA oncoprotein. On the other hand, CagA interactions with host cell partners interfere with cellular pathways to subvert cell defences and to promote H. pylori infection. Although a clear mechanism for CagA translocation is still lacking, the structural definition of CagA and CagL domains involved in interactions with signalling proteins are progressively coming to light. In this chapter, we will focus on the structural aspects of Cag protein interactions with host cell molecules, critical molecular events precluding H. pylori-mediated gastric cancer development.
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15
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Kumar N, Shariq M, Kumar A, Kumari R, Subbarao N, Tyagi RK, Mukhopadhyay G. Analyzing the role of CagV, a VirB8 homolog of the type IV secretion system of Helicobacter pylori. FEBS Open Bio 2017; 7:915-933. [PMID: 28680806 PMCID: PMC5494299 DOI: 10.1002/2211-5463.12225] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/22/2017] [Accepted: 02/24/2017] [Indexed: 12/13/2022] Open
Abstract
The type IV secretion system of Helicobacter pylori (Cag‐T4SS) is composed of ~ 27 components including a VirB8 homolog, CagV. We have characterized CagV and reported that it is an inner membrane protein and, like VirB8, forms a homodimer. Its stability is not dependent on the other Cag components and the absence of cagV affects the stability of only CagI, a protein involved in pilus formation. CagV is not required for the stability and localization of outer membrane subcomplex proteins, but interacts with them through CagX. It also interacts with the inner membrane‐associated components, CagF and CagZ, and is required for the surface localization of CagA. The results of this study might help in deciphering the mechanistic contributions of CagV in the Cag‐T4SS biogenesis and function.
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Affiliation(s)
- Navin Kumar
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India.,Present address: School of Biotechnology Gautam Buddha University Yamuna Expressway Greater Noida Gautam Budh Nagar Uttar Pradesh India
| | - Mohd Shariq
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India.,Present address: School of Life Sciences Jawaharlal Nehru University New Delhi India
| | - Amarjeet Kumar
- School of Computational and Integrative Sciences Jawaharlal Nehru University New Delhi India
| | - Rajesh Kumari
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India
| | - Naidu Subbarao
- School of Computational and Integrative Sciences Jawaharlal Nehru University New Delhi India
| | - Rakesh K Tyagi
- Special Centre for Molecular Medicine Jawaharlal Nehru University New Delhi India
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16
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Merino E, Flores-Encarnación M, Aguilar-Gutiérrez GR. Functional interaction and structural characteristics of unique components of Helicobacter pylori T4SS. FEBS J 2017; 284:3540-3549. [PMID: 28470874 DOI: 10.1111/febs.14092] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 03/14/2017] [Accepted: 04/26/2017] [Indexed: 12/25/2022]
Abstract
The Helicobacter pylori infection of the human gastric mucosa causes chronic active gastritis and peptic ulcers and is associated with the development of gastric cancer. Epidemiological studies show that these gastric diseases are related to virulent H. pylori strains that harbor the cytotoxin-associated gene pathogenicity island (cag PAI). The cag PAI is a DNA insertion in the H. pylori chromosome that encodes ~ 27 proteins, including the oncoprotein CagA. Approximately 20 of these proteins have been designated as cag type IV secretion system (T4SS) components. However, only 11 of these proteins share function, structure, and/or sequence similarities with the prototypical VirB/VirD4 T4SS of Agrobacterium tumefaciens. The VirB/VirD4 orthologs of the cag T4SS of H. pylori are required for CagA translocation and stimulate the gastric epithelial cells to produce and secrete interleukin-8 (IL-8). The cag PAI encodes eight additional proteins, such as Cag3 (Cagδ/HP0522), CagM (Cag16/HP0537), CagU (Cag11/HP0531), CagI (Cag19/HP0540), and CagH (Cag20/HP0541), which are also required for the translocation of CagA and IL-8 secretion, meanwhile CagF (Cag22/HP0543), CagG (Cag21/HP0542), and CagZ (Cag6/HP0526) are just required for the translocation of CagA. However, relatively little is known about their functions and structural organization because they exhibit a nondetectable sequence similarity with T4SS components in the current databases. In this review, we conducted an exhaustive analysis of the literature to present the biochemistry, putative role, localization, and interactions of each of these eight additional cag T4SS components.
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Affiliation(s)
- Enrique Merino
- Enrique Merino, Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Marcos Flores-Encarnación
- Marcos Flores-Encarnación, Laboratorio de Microbiología Molecular y Celular, Facultad de Medicina, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Germán Rubén Aguilar-Gutiérrez
- Germán Rubén Aguilar-Gutiérrez, Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México
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17
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Kumari R, Shariq M, Kumar N, Mukhopadhyay G. Biochemical characterization of theHelicobacter pyloriCag-type IV secretion system unique component CagU. FEBS Lett 2017; 591:500-512. [DOI: 10.1002/1873-3468.12564] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 12/16/2016] [Accepted: 01/10/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Rajesh Kumari
- Special Centre for Molecular Medicine; Jawaharlal Nehru University; New Delhi India
| | - Mohd Shariq
- Special Centre for Molecular Medicine; Jawaharlal Nehru University; New Delhi India
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| | - Navin Kumar
- Special Centre for Molecular Medicine; Jawaharlal Nehru University; New Delhi India
- School of Biotechnology; Gautam Buddha University; Uttar Pradesh India
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18
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Wang H, Yao Y, Ni B, Shen Y, Wang X, Shen H, Shao S. Helicobacter pylori CagI is associated with the stability of CagA. Microb Pathog 2016; 99:130-134. [DOI: 10.1016/j.micpath.2016.07.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 07/19/2016] [Accepted: 07/19/2016] [Indexed: 01/25/2023]
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19
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Gonzalez-Rivera C, Bhatty M, Christie PJ. Mechanism and Function of Type IV Secretion During Infection of the Human Host. Microbiol Spectr 2016; 4:10.1128/microbiolspec.VMBF-0024-2015. [PMID: 27337453 PMCID: PMC4920089 DOI: 10.1128/microbiolspec.vmbf-0024-2015] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Indexed: 02/07/2023] Open
Abstract
Bacterial pathogens employ type IV secretion systems (T4SSs) for various purposes to aid in survival and proliferation in eukaryotic hosts. One large T4SS subfamily, the conjugation systems, confers a selective advantage to the invading pathogen in clinical settings through dissemination of antibiotic resistance genes and virulence traits. Besides their intrinsic importance as principle contributors to the emergence of multiply drug-resistant "superbugs," detailed studies of these highly tractable systems have generated important new insights into the mode of action and architectures of paradigmatic T4SSs as a foundation for future efforts aimed at suppressing T4SS machine function. Over the past decade, extensive work on the second large T4SS subfamily, the effector translocators, has identified a myriad of mechanisms employed by pathogens to subvert, subdue, or bypass cellular processes and signaling pathways of the host cell. An overarching theme in the evolution of many effectors is that of molecular mimicry. These effectors carry domains similar to those of eukaryotic proteins and exert their effects through stealthy interdigitation of cellular pathways, often with the outcome not of inducing irreversible cell damage but rather of reversibly modulating cellular functions. This article summarizes the major developments for the actively studied pathogens with an emphasis on the structural and functional diversity of the T4SSs and the emerging common themes surrounding effector function in the human host.
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Affiliation(s)
- Christian Gonzalez-Rivera
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, Phone: 713-500-5440 (P. J. Christie); 713-500-5441 (C. Gonzalez-Rivera, M. Bhatty)
| | - Minny Bhatty
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, Phone: 713-500-5440 (P. J. Christie); 713-500-5441 (C. Gonzalez-Rivera, M. Bhatty)
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, Phone: 713-500-5440 (P. J. Christie); 713-500-5441 (C. Gonzalez-Rivera, M. Bhatty)
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20
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Schindele F, Weiss E, Haas R, Fischer W. Quantitative analysis of CagA type IV secretion byHelicobacterpylorireveals substrate recognition and translocation requirements. Mol Microbiol 2016; 100:188-203. [DOI: 10.1111/mmi.13309] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2015] [Indexed: 12/15/2022]
Affiliation(s)
- Franziska Schindele
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität; München Germany
- German Center for Infection Research (Deutsches Zentrum für Infektionsforschung; DZIF), Ludwig-Maximilians-Universität; München Germany
| | - Evelyn Weiss
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität; München Germany
| | - Rainer Haas
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität; München Germany
- German Center for Infection Research (Deutsches Zentrum für Infektionsforschung; DZIF), Ludwig-Maximilians-Universität; München Germany
| | - Wolfgang Fischer
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität; München Germany
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21
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Molecular and Structural Analysis of the Helicobacter pylori cag Type IV Secretion System Core Complex. mBio 2016; 7:e02001-15. [PMID: 26758182 PMCID: PMC4725015 DOI: 10.1128/mbio.02001-15] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bacterial type IV secretion systems (T4SSs) can function to export or import DNA, and can deliver effector proteins into a wide range of target cells. Relatively little is known about the structural organization of T4SSs that secrete effector proteins. In this report, we describe the isolation and analysis of a membrane-spanning core complex from the Helicobacter pylori cag T4SS, which has an important role in the pathogenesis of gastric cancer. We show that this complex contains five H. pylori proteins, CagM, CagT, Cag3, CagX, and CagY, each of which is required for cag T4SS activity. CagX and CagY are orthologous to the VirB9 and VirB10 components of T4SSs in other bacterial species, and the other three Cag proteins are unique to H. pylori. Negative stain single-particle electron microscopy revealed complexes 41 nm in diameter, characterized by a 19-nm-diameter central ring linked to an outer ring by spoke-like linkers. Incomplete complexes formed by Δcag3 or ΔcagT mutants retain the 19-nm-diameter ring but lack an organized outer ring. Immunogold labeling studies confirm that Cag3 is a peripheral component of the complex. The cag T4SS core complex has an overall diameter and structural organization that differ considerably from the corresponding features of conjugative T4SSs. These results highlight specialized features of the H. pylori cag T4SS that are optimized for function in the human gastric mucosal environment. Type IV secretion systems (T4SSs) are versatile macromolecular machines that are present in many bacterial species. In this study, we investigated a T4SS found in the bacterium Helicobacter pylori. H. pylori is an important cause of stomach cancer, and the H. pylori T4SS contributes to cancer pathogenesis by mediating entry of CagA (an effector protein regarded as a “bacterial oncoprotein”) into gastric epithelial cells. We isolated and analyzed the membrane-spanning core complex of the H. pylori T4SS and showed that it contains unique proteins unrelated to components of T4SSs in other bacterial species. These results constitute the first structural analysis of the core complex from this important secretion system.
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22
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Shariq M, Kumar N, Kumari R, Kumar A, Subbarao N, Mukhopadhyay G. Biochemical Analysis of CagE: A VirB4 Homologue of Helicobacter pylori Cag-T4SS. PLoS One 2015; 10:e0142606. [PMID: 26565397 PMCID: PMC4643968 DOI: 10.1371/journal.pone.0142606] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/23/2015] [Indexed: 12/30/2022] Open
Abstract
Helicobacter pylori are among the most successful human pathogens that harbour a distinct genomic segment called cag Pathogenicity Island (cag-PAI). This genomic segment codes for a type IV secretion system (Cag-T4SS) related to the prototypical VirB/D4 system of Agrobacterium tumefaciens (Ag), a plant pathogen. Some of the components of Cag-T4SS share homology to that of VirB proteins including putative energy providing CagE (HP0544), the largest VirB4 homologue. In Ag, VirB4 is required for the assembly of the system, substrate translocation and pilus formation, however, very little is known about CagE. Here we have characterised the protein biochemically, genetically, and microscopically and report that CagE is an inner membrane associated active NTPase and has multiple interacting partners including the inner membrane proteins CagV and Cagβ. Through CagV it is connected to the outer membrane sub-complex proteins. Stability of CagE is not dependent on several of the cag-PAI proteins tested. However, localisation and stability of the pilus associated CagI, CagL and surface associated CagH are affected in its absence. Stability of the inner membrane associated energetic component Cagβ, a VirD4 homologue seems to be partially affected in its absence. Additionally, CagA failed to cross the membrane barriers in its absence and no IL-8 induction is observed under infection condition. These results thus suggest the importance of CagE in Cag-T4SS functions. In future it may help in deciphering the mechanism of substrate translocation by the system.
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Affiliation(s)
- Mohd Shariq
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- * E-mail: (MS); (GM)
| | - Navin Kumar
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Rajesh Kumari
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Amarjeet Kumar
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Naidu Subbarao
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Gauranga Mukhopadhyay
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
- * E-mail: (MS); (GM)
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23
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Immune Homeostasis of Human Gastric Mucosa in Helicobacter pylori Infection. Bull Exp Biol Med 2015; 159:157-63. [PMID: 26033608 DOI: 10.1007/s10517-015-2913-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Indexed: 01/21/2023]
Abstract
We present the results of electron microscopic, microbiological, immunohistochemical, and molecular genetic studies of gastric biopsy specimens taken for diagnostic purposes according by clinical indications during examination of patients with gastrointestinal pathology. Immune homeostasis of the gastric mucosa against the background of infection with various pathogen strains of Helicobacter pylori was studied in patients of different age groups with peptic ulcer, gastritis, metaplasia, and cancer. Some peculiarities of Helicobacter pylori contamination in the gastric mucosa were demonstrated. Immune homeostasis of the gastric mucosa in different pathologies was analyzed depending on the Helicobacter pylori genotype.
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24
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Reingewertz TH, Iosub-Amir A, Bonsor DA, Mayer G, Amartely H, Friedler A, Sundberg EJ. An Intrinsically Disordered Region in the Proapoptotic ASPP2 Protein Binds to the Helicobacter pylori Oncoprotein CagA. Biochemistry 2015; 54:3337-47. [PMID: 25963096 DOI: 10.1021/acs.biochem.5b00084] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The leading risk factor for gastric cancer in humans is infection by Helicobacter pylori strains that express and translocate the oncoprotein CagA into host epithelial cells. Once inside host cells, CagA interacts with ASPP2, which specifically stimulates p53-mediated apoptosis and reverses its pro-apoptotic function to promote ASPP2-dependent degradation of p53. The X-ray crystal structure of a complex between the N-terminal domain of CagA and a 56-residue fragment of ASPP2, of which 22 residues were resolved, was recently described. Here, we present biochemical and biophysical analyses of the interaction between the additional regions of CagA and ASPP2 potentially involved in this interaction. Using size exclusion chromatography-multiangle laser light scattering, circular dichroism, and nuclear magnetic resonance analyses, we observed that the ASPP2 region spanning residues 331-692, which was not part of the ASPP2 fragment used for crystallization, is intrinsically disordered in its unbound state. By surface plasmon resonance analysis and isothermal titration calorimetry, we found that a portion of this disordered region in ASPP2, residues 448-692, binds to the N-terminal domain of CagA. We also measured the affinity of the complex between the ASPP2 fragment composed of residues 693-918 and inclusive of the fragment used for crystallization and CagA. Additionally, we mapped the binding regions between ASPP2 and CagA using peptide arrays, demonstrating interactions between CagA and numerous peptides distributed throughout the ASPP2 protein sequence. Our results identify previously uncharacterized regions distributed throughout the protein sequence of ASPP2 as determinants of CagA binding, providing mechanistic insight into apoptosis reprogramming by CagA and potential new drug targets for H. pylori-mediated gastric cancer.
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Affiliation(s)
| | - Anat Iosub-Amir
- ‡Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | | | - Guy Mayer
- ‡Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Hadar Amartely
- ‡Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Assaf Friedler
- ‡Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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25
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Zanotti G, Cendron L. Structural and functional aspects of the Helicobacter pylori secretome. World J Gastroenterol 2014; 20:1402-1423. [PMID: 24587618 PMCID: PMC3925851 DOI: 10.3748/wjg.v20.i6.1402] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 01/06/2014] [Indexed: 02/06/2023] Open
Abstract
Proteins secreted by Helicobacter pylori (H. pylori), an important human pathogen responsible for severe gastric diseases, are reviewed from the point of view of their biochemical characterization, both functional and structural. Despite the vast amount of experimental data available on the proteins secreted by this bacterium, the precise size of the secretome remains unknown. In this review, we consider as secreted both proteins that contain a secretion signal for the periplasm and proteins that have been detected in the external medium in in vitro experiments. In this way, H. pylori’s secretome appears to be composed of slightly more than 160 proteins, but this number must be considered very cautiously, not only because the definition of secretome itself is ambiguous but also because the included proteins were observed as secreted in in vitro experiments that were not representative of the environmental situation in vivo. The proteins that appear to be secreted can be grouped into different classes: enzymes (48 proteins), outer membrane proteins (43), components of flagella (11), members of the cytotoxic-associated genes pathogenicity island or other toxins (8 and 5, respectively), binding and transport proteins (9), and others (11). A final group, which includes 28 members, is represented by hypothetical uncharacterized proteins. Despite the large amount of data accumulated on the H. pylori secretome, a considerable amount of work remains to reach a full comprehension of the system at the molecular level.
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26
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Christie PJ, Whitaker N, González-Rivera C. Mechanism and structure of the bacterial type IV secretion systems. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1578-91. [PMID: 24389247 DOI: 10.1016/j.bbamcr.2013.12.019] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/20/2013] [Accepted: 12/23/2013] [Indexed: 01/25/2023]
Abstract
The bacterial type IV secretion systems (T4SSs) translocate DNA and protein substrates to bacterial or eukaryotic target cells generally by a mechanism dependent on direct cell-to-cell contact. The T4SSs encompass two large subfamilies, the conjugation systems and the effector translocators. The conjugation systems mediate interbacterial DNA transfer and are responsible for the rapid dissemination of antibiotic resistance genes and virulence determinants in clinical settings. The effector translocators are used by many Gram-negative bacterial pathogens for delivery of potentially hundreds of virulence proteins to eukaryotic cells for modulation of different physiological processes during infection. Recently, there has been considerable progress in defining the structures of T4SS machine subunits and large machine subassemblies. Additionally, the nature of substrate translocation sequences and the contributions of accessory proteins to substrate docking with the translocation channel have been elucidated. A DNA translocation route through the Agrobacterium tumefaciens VirB/VirD4 system was defined, and both intracellular (DNA ligand, ATP energy) and extracellular (phage binding) signals were shown to activate type IV-dependent translocation. Finally, phylogenetic studies have shed light on the evolution and distribution of T4SSs, and complementary structure-function studies of diverse systems have identified adaptations tailored for novel functions in pathogenic settings. This review summarizes the recent progress in our understanding of the architecture and mechanism of action of these fascinating machines, with emphasis on the 'archetypal' A. tumefaciens VirB/VirD4 T4SS and related conjugation systems. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Peter J Christie
- Department of Microbiology and Molecular Genetics, UT-Houston Medical School, 6431 Fannin, JFB1.765, Houston, TX 77030, USA.
| | - Neal Whitaker
- Department of Microbiology and Molecular Genetics, UT-Houston Medical School, 6431 Fannin, JFB1.765, Houston, TX 77030, USA
| | - Christian González-Rivera
- Department of Microbiology and Molecular Genetics, UT-Houston Medical School, 6431 Fannin, JFB1.765, Houston, TX 77030, USA
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27
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Bonsor DA, Weiss E, Iosub-Amir A, Reingewertz TH, Chen TW, Haas R, Friedler A, Fischer W, Sundberg EJ. Characterization of the translocation-competent complex between the Helicobacter pylori oncogenic protein CagA and the accessory protein CagF. J Biol Chem 2013; 288:32897-909. [PMID: 24072713 DOI: 10.1074/jbc.m113.507657] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
CagA is a virulence factor that Helicobacter pylori inject into gastric epithelial cells through a type IV secretion system where it can cause gastric adenocarcinoma. Translocation is dependent on the presence of secretion signals found in both the N- and C-terminal domains of CagA and an interaction with the accessory protein CagF. However, the molecular basis of this essential protein-protein interaction is not fully understood. Herein we report, using isothermal titration calorimetry, that CagA forms a 1:1 complex with a monomer of CagF with nM affinity. Peptide arrays and isothermal titration calorimetry both show that CagF binds to all five domains of CagA, each with μM affinity. More specifically, a coiled coil domain and a C-terminal helix within CagF contacts domains II-III and domain IV of CagA, respectively. In vivo complementation assays of H. pylori with a double mutant, L36A/I39A, in the coiled coil region of CagF showed a severe weakening of the CagA-CagF interaction to such an extent that it was nearly undetectable. However, it had no apparent effect on CagA translocation. Deletion of the C-terminal helix of CagF also weakened the interaction with CagA but likewise had no effect on translocation. These results indicate that the CagA-CagF interface is distributed broadly across the molecular surfaces of these two proteins to provide maximal protection of the highly labile effector protein CagA.
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28
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The Helicobacter pylori protein CagM is located in the transmembrane channel that is required for CagA translocation. Curr Microbiol 2013; 67:531-6. [PMID: 23736225 DOI: 10.1007/s00284-013-0402-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 04/30/2013] [Indexed: 12/15/2022]
Abstract
Helicobacter pylori (H. pylori) is a human gastric pathogen that colonizes the stomach in more than 50 % of the world's human population. Infection with this bacterium can induce several gastric diseases ranging from gastritis to peptic ulcer and gastric cancer. Virulent H. pylori isolates harboring the cag pathogenicity island (cag PAI), which encodes a Type IV Secretion System (T4SS), form a pilus for the injection of its major virulence protein CagA into gastric cells. Several cag PAI genes have been identified as homologues of T4SS genes from Agrobacterium tumefaciens, while the other members in cag PAI still have no known function. We studied one of such proteins with unknown function, CagM, which was predicted to have a putative N-terminal signal sequence and at least three transmembrane helices. To determine the subcellular localization of CagM, we performed a cell fractionation procedure and produced rabbit anti-CagM polyclonal antibodies for immunoblotting assays. Furthermore, we generated an isogenic ΔcagM mutant to investigate the ability of CagA translocation compared with the wild-type NCTC 11637 strain using GES-1 and MKN-45 cell infection experiments. Our results indicated that CagM was mainly located in the bacterial membrane, partially located in the periplasm, and essential for CagA translocation both in GES-1 and MKN-45 cells, which suggested that CagM was one of the core members of Cag T4SS and localized in the transmembrane channel.
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Structural insights into Helicobacter pylori oncoprotein CagA interaction with β1 integrin. Proc Natl Acad Sci U S A 2012; 109:14640-5. [PMID: 22908298 DOI: 10.1073/pnas.1206098109] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Infection with the gastric pathogen Helicobacter pylori is a risk factor for the development of gastric cancer. Pathogenic strains of H. pylori carry a type IV secretion system (T4SS) responsible for the injection of the oncoprotein CagA into host cells. H. pylori and its cag-T4SS exploit α5β1 integrin as a receptor for CagA translocation. Injected CagA localizes to the inner leaflet of the host cell membrane, where it hijacks host cell signaling and induces cytoskeleton reorganization. Here we describe the crystal structure of the N-terminal ~100-kDa subdomain of CagA at 3.6 Å that unveils a unique combination of folds. The core domain of the protein consists of an extended single-layer β-sheet stabilized by two independent helical subdomains. The core is followed by a long helix that forms a four-helix helical bundle with the C-terminal domain. Mapping of conserved regions in a set of CagA sequences identified four conserved surface-exposed patches (CSP1-4), which represent putative hot-spots for protein-protein interactions. The proximal part of the single-layer β-sheet, covering CSP4, is involved in specific binding of CagA to the β1 integrin, as determined by yeast two-hybrid and in vivo competition assays in H. pylori cell-culture infection studies. These data provide a structural basis for the first step of CagA internalization into host cells and suggest that CagA uses a previously undescribed mechanism to bind β1 integrin to mediate its own translocation.
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Zechner EL, Lang S, Schildbach JF. Assembly and mechanisms of bacterial type IV secretion machines. Philos Trans R Soc Lond B Biol Sci 2012; 367:1073-87. [PMID: 22411979 PMCID: PMC3297438 DOI: 10.1098/rstb.2011.0207] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Type IV secretion occurs across a wide range of prokaryotic cell envelopes: Gram-negative, Gram-positive, cell wall-less bacteria and some archaea. This diversity is reflected in the heterogeneity of components that constitute the secretion machines. Macromolecules are secreted in an ATP-dependent process using an envelope-spanning multi-protein channel. Similar to the type III systems, this apparatus extends beyond the cell surface as a pilus structure important for direct contact and penetration of the recipient cell surface. Type IV systems are remarkably versatile in that they mobilize a broad range of substrates, including single proteins, protein complexes, DNA and nucleoprotein complexes, across the cell envelope. These machines have broad clinical significance not only for delivering bacterial toxins or effector proteins directly into targeted host cells, but also for direct involvement in phenomena such as biofilm formation and the rapid horizontal spread of antibiotic resistance genes among the microbial community.
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Affiliation(s)
- Ellen L Zechner
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/I, Graz 8010, Austria.
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Wang H, Han J, Chen D, Duan X, Gao X, Wang X, Shao S. Characterization of CagI in the cag pathogenicity island of Helicobacter pylori. Curr Microbiol 2011; 64:191-6. [PMID: 22109855 DOI: 10.1007/s00284-011-0043-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 10/24/2011] [Indexed: 02/06/2023]
Abstract
Helicobacter pylori is a highly successful human-specific gastric pathogen that infects up to 50% of the world's population. Virulent H. pylori isolates harbor the cytotoxin-associated genes pathogenicity island (cag-PAI), which encodes a type IV secretion system that translocates bacterial effector (e.g., CagA oncoprotein) molecules into host cells. Although some cag-PAI genes are shown to be required for CagA delivery or localization, the majority have no known function. In the current study, the authors performed a cell components fractionation assay and showed that CagI, one of the cag-PAI proteins located in the bacterial membrane, was not translocated into host cells. The homologous recombination method then was used to construct the isogenic mutant of H. pylori cagI, and the translocation assay was performed. The results showed that the isogenic mutant of H. pylori NCTC 11637 cagI could cause a reduction in the degree of CagA translocation. Overall, the results suggested that CagI might be an accessory component of the CagA secretion system not translocated into host cells and that it is located in the bacterial membrane.
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Affiliation(s)
- Hua Wang
- School of Medical Science and Laboratory Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013 Jiangsu, People's Republic of China
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Molecular mechanisms of gastric epithelial cell adhesion and injection of CagA by Helicobacter pylori. Cell Commun Signal 2011; 9:28. [PMID: 22044679 PMCID: PMC3266215 DOI: 10.1186/1478-811x-9-28] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Accepted: 11/01/2011] [Indexed: 02/08/2023] Open
Abstract
Helicobacter pylori is a highly successful pathogen uniquely adapted to colonize humans. Gastric infections with this bacterium can induce pathology ranging from chronic gastritis and peptic ulcers to gastric cancer. More virulent H. pylori isolates harbour numerous well-known adhesins (BabA/B, SabA, AlpA/B, OipA and HopZ) and the cag (cytotoxin-associated genes) pathogenicity island encoding a type IV secretion system (T4SS). The adhesins establish tight bacterial contact with host target cells and the T4SS represents a needle-like pilus device for the delivery of effector proteins into host target cells such as CagA. BabA and SabA bind to blood group antigen and sialylated proteins respectively, and a series of T4SS components including CagI, CagL, CagY and CagA have been shown to target the integrin β1 receptor followed by injection of CagA across the host cell membrane. The interaction of CagA with membrane-anchored phosphatidylserine may also play a role in the delivery process. While substantial progress has been made in our current understanding of many of the above factors, the host cell receptors for OipA, HopZ and AlpA/B during infection are still unknown. Here we review the recent progress in characterizing the interactions of the various adhesins and structural T4SS proteins with host cell factors. The contribution of these interactions to H. pylori colonization and pathogenesis is discussed.
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Cendron L, Zanotti G. Structural and functional aspects of unique type IV secretory components in the Helicobacter pylori cag-pathogenicity island. FEBS J 2011; 278:1223-31. [PMID: 21284804 DOI: 10.1111/j.1742-4658.2011.08038.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Helicobacter pylori cytotoxin-associated gene-pathogenicity island (cagPAI) is responsible for the secretion of the CagA effector through a type IV secretion system (T4SS) apparatus, as well as of peptidoglycan and possibly other not yet identified factors. Twenty-nine different polypeptide chains are encoded by this cluster of genes, although only some of them show a significant similarity with the constitutive elements of well characterized secretion systems from other bacteria. The other cagPAI components represent almost unique proteins in this scenario. The majority of the T4SS include approximately fifteen components, taking into account either the transmembrane complex subunits, ATPases or substrate factors. The composition of the cagPAI is very complex: it includes proteins most likely involved at different levels in the pilus assembly, stabilization and processing of secreted substrate, as well as regulatory particles possibly involved in the control of the entire apparatus. Despite recent findings with respect to components that play a role in the interaction with the host cell, the function of several cagPAI proteins remains unclear or unknown. This is particularly true for those that represent unique members with no clear similarity to those of other T4SS and no obvious evidence of involvement in the secretion of CagA or induction of pro-inflammatory responses. We summarize what is known about these accessory components, both from a molecular and structural point of view, as well as their putative physiological role.
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Affiliation(s)
- Laura Cendron
- Department of Biological Chemistry, University of Padua, Padua, Italy
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Fischer W. Assembly and molecular mode of action of the Helicobacter pylori Cag type IV secretion apparatus. FEBS J 2011; 278:1203-12. [PMID: 21352490 DOI: 10.1111/j.1742-4658.2011.08036.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bacterial type IV secretion systems (T4SS) form supramolecular protein complexes that are capable of transporting DNA or protein substrates across the bacterial cell envelope and, in many cases, also across eukaryotic target cell membranes. Because of these characteristics, they are often used by pathogenic bacteria for the injection of host cell-modulating virulence factors. One example is the human pathogen Helicobacter pylori, which uses the Cag-T4SS to induce a pro-inflammatory response and multiple cytoskeletal and gene regulatory effects in gastric epithelial cells. Work in recent years has shown that the Cag-T4SS exhibits marked differences in relation to other systems, both with respect to the composition of its secretion apparatus and the molecular details of its secretion mechanisms. This review describes the molecular properties of the Cag-T4SS and compares these with prototypical systems of this family of protein transporters.
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Affiliation(s)
- Wolfgang Fischer
- Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität, München, Germany.
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Hatakeyama M. Anthropological and clinical implications for the structural diversity of the Helicobacter pylori CagA oncoprotein. Cancer Sci 2011; 102:36-43. [PMID: 20942897 PMCID: PMC11159401 DOI: 10.1111/j.1349-7006.2010.01743.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Helicobacter pylori CagA is the first bacterial oncoprotein to be identified in relation to human cancer. CagA is delivered into gastric epithelial cells through a bacterial type IV secretion system and localizes to the plasma membrane, where it undergoes tyrosine phosphorylation by host cell kinases. Membrane-localized CagA then mimics mammalian scaffold proteins and perturbs a number of host signaling pathways in both tyrosine phosphorylation-dependent and -independent manners, thereby promoting transformation of gastric epithelial cells. Helicobacter pylori CagA is noted for structural diversity in its C-terminal region, with which CagA interacts with numerous host cell proteins. This CagA polymorphism is primarily due to differential combination and alignment of the four distinct EPIYA segments and the two different CagA-multimerization sequences in making the C-terminal region. The structural diversity substantially influences the pathophysiological action of CagA. This review focuses on the molecular basis for the structural polymorphism that determines the degrees of virulence and oncogenic potential of individual CagA. The pylogeographic distribution of differential CagA isoforms is also discussed in the context of human migration history, which may underlie large geographical variations in the incidence of gastric cancer in different parts of the world.
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Affiliation(s)
- Masanori Hatakeyama
- Division of Microbiology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
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Abstract
Helicobacter pylori plays an essential role in the development of various gastroduodenal diseases; however, only a small proportion of people infected with H. pylori develop these diseases. Some populations that have a high prevalence of H. pylori infection also have a high incidence of gastric cancer (for example, in East Asia), whereas others do not (for example, in Africa and South Asia). Even within East Asia, the incidence of gastric cancer varies (decreasing in the south). H. pylori is a highly heterogeneous bacterium and its virulence varies geographically. Geographic differences in the incidence of gastric cancer can be explained, at least in part, by the presence of different types of H. pylori virulence factor, especially CagA, VacA and OipA. However, it is still unclear why the pathogenicity of H. pylori increased as it migrated from Africa to East Asia during the course of evolution. H. pylori infection is also thought to be involved in the development of duodenal ulcer, which is at the opposite end of the disease spectrum to gastric cancer. This discrepancy can be explained in part by the presence of H. pylori virulence factor DupA. Despite advances in our understanding of the development of H. pylori-related diseases, further work is required to clarify the roles of H. pylori virulence factors.
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Affiliation(s)
- Yoshio Yamaoka
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Idaigaoka, Hasama-machi, Yufucity, Oita 879-5593, Japan.
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Abstract
Helicobacter pylori plays an essential role in the development of various gastroduodenal diseases; however, only a small proportion of people infected with H. pylori develop these diseases. Some populations that have a high prevalence of H. pylori infection also have a high incidence of gastric cancer (for example, in East Asia), whereas others do not (for example, in Africa and South Asia). Even within East Asia, the incidence of gastric cancer varies (decreasing in the south). H. pylori is a highly heterogeneous bacterium and its virulence varies geographically. Geographic differences in the incidence of gastric cancer can be explained, at least in part, by the presence of different types of H. pylori virulence factor, especially CagA, VacA and OipA. However, it is still unclear why the pathogenicity of H. pylori increased as it migrated from Africa to East Asia during the course of evolution. H. pylori infection is also thought to be involved in the development of duodenal ulcer, which is at the opposite end of the disease spectrum to gastric cancer. This discrepancy can be explained in part by the presence of H. pylori virulence factor DupA. Despite advances in our understanding of the development of H. pylori-related diseases, further work is required to clarify the roles of H. pylori virulence factors.
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Affiliation(s)
- Yoshio Yamaoka
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Idaigaoka, Hasamamachi, Yufucity, Oita 879-5593, Japan
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The coupling protein Cagbeta and its interaction partner CagZ are required for type IV secretion of the Helicobacter pylori CagA protein. Infect Immun 2010; 78:5244-51. [PMID: 20876293 DOI: 10.1128/iai.00796-10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacterial type IV secretion systems are macromolecule transporters with essential functions for horizontal gene transfer and for symbiotic and pathogenic interactions with eukaryotic host cells. Helicobacter pylori, the causative agent of type B gastritis, peptic ulcers, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma, uses the Cag type IV secretion system to inject its effector protein CagA into gastric cells. This protein translocation results in altered host cell gene expression profiles and cytoskeletal rearrangements, and it has been linked to cancer development. Interactions of CagA with host cell proteins have been studied in great detail, but little is known about the molecular details of CagA recognition as a type IV secretion substrate or of the translocation process. Apart from components of the secretion apparatus, we previously identified several CagA translocation factors that are either required for or support CagA translocation. To identify protein-protein interactions between these translocation factors, we used a yeast two-hybrid approach comprising all cag pathogenicity island genes. Among several other interactions involving translocation factors, we found a strong interaction between the coupling protein homologue Cagβ (HP0524) and the Cag-specific translocation factor CagZ (HP0526). We show that CagZ has a stabilizing effect on Cagβ, and we demonstrate protein-protein interactions between the cytoplasmic part of Cagβ and CagA and between CagZ and Cagβ, using immunoprecipitation and pull-down assays. Together, our data suggest that these interactions represent a substrate-translocation factor complex at the bacterial cytoplasmic membrane.
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Olbermann P, Josenhans C, Moodley Y, Uhr M, Stamer C, Vauterin M, Suerbaum S, Achtman M, Linz B. A global overview of the genetic and functional diversity in the Helicobacter pylori cag pathogenicity island. PLoS Genet 2010; 6:e1001069. [PMID: 20808891 PMCID: PMC2924317 DOI: 10.1371/journal.pgen.1001069] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 07/15/2010] [Indexed: 12/16/2022] Open
Abstract
The Helicobacter pylori cag pathogenicity island (cagPAI) encodes a type IV secretion system. Humans infected with cagPAI–carrying H. pylori are at increased risk for sequelae such as gastric cancer. Housekeeping genes in H. pylori show considerable genetic diversity; but the diversity of virulence factors such as the cagPAI, which transports the bacterial oncogene CagA into host cells, has not been systematically investigated. Here we compared the complete cagPAI sequences for 38 representative isolates from all known H. pylori biogeographic populations. Their gene content and gene order were highly conserved. The phylogeny of most cagPAI genes was similar to that of housekeeping genes, indicating that the cagPAI was probably acquired only once by H. pylori, and its genetic diversity reflects the isolation by distance that has shaped this bacterial species since modern humans migrated out of Africa. Most isolates induced IL-8 release in gastric epithelial cells, indicating that the function of the Cag secretion system has been conserved despite some genetic rearrangements. More than one third of cagPAI genes, in particular those encoding cell-surface exposed proteins, showed signatures of diversifying (Darwinian) selection at more than 5% of codons. Several unknown gene products predicted to be under Darwinian selection are also likely to be secreted proteins (e.g. HP0522, HP0535). One of these, HP0535, is predicted to code for either a new secreted candidate effector protein or a protein which interacts with CagA because it contains two genetic lineages, similar to cagA. Our study provides a resource that can guide future research on the biological roles and host interactions of cagPAI proteins, including several whose function is still unknown. Most humans are infected with Helicobacter pylori. The H. pylori cag pathogenicity island (cagPAI) encodes a secretion apparatus that can translocate the CagA protein into host cells. Humans infected with cagPAI–carrying H. pylori are at increased risk of severe disease, including gastric cancer. We analyzed the nucleotide sequences and functional diversity of the cagPAI in a globally representative collection of isolates. Complete cagPAI sequences were obtained for 29 strains from all known H. pylori biogeographic populations. The gene content and arrangement of the cagPAI and its function were highly conserved. Diversity in most cag genes consisted in large part of synonymous polymorphisms. However some genes—in particular those that encode proteins predicted to be secreted or located on the outside of the bacterial cell—had particularly high frequencies of non-synonymous polymorphisms, suggesting that they were under diversifying selection. Our study provides evidence that the cagPAI was only acquired once and provides an important resource that can guide future research on the biological roles and host interactions of cagPAI proteins, including several whose function is still unknown.
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Affiliation(s)
- Patrick Olbermann
- Institute for Medical Microbiology and Hospital Epidemiology, Medizinische Hochschule Hannover, Hannover, Germany
| | - Christine Josenhans
- Institute for Medical Microbiology and Hospital Epidemiology, Medizinische Hochschule Hannover, Hannover, Germany
| | - Yoshan Moodley
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Markus Uhr
- Institute for Medical Microbiology and Hospital Epidemiology, Medizinische Hochschule Hannover, Hannover, Germany
| | - Christiana Stamer
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | | | - Sebastian Suerbaum
- Institute for Medical Microbiology and Hospital Epidemiology, Medizinische Hochschule Hannover, Hannover, Germany
- * E-mail: ;
| | - Mark Achtman
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
- Environmental Research Institute, University College Cork, Cork, Ireland
- * E-mail: ;
| | - Bodo Linz
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
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Abstract
Several bacterial pathogens inject virulence proteins into host target cells that are substrates of eukaryotic tyrosine kinases. One of the key examples is the Helicobacter pylori CagA effector protein which is translocated by a type-IV secretion system. Injected CagA becomes tyrosine-phosphorylated on EPIYA sequence motifs by Src and Abl family kinases. CagA then binds to and activates/inactivates multiple signaling proteins in a phosphorylation-dependent and phosphorylation-independent manner. A recent proteomic screen systematically identified eukaryotic binding partners of the EPIYA phosphorylation sites of CagA and similar sites in other bacterial effectors by high-resolution mass spectrometry. Individual phosphorylation sites recruited a surprisingly high number of interaction partners suggesting that each phosphorylation site can interfere with many downstream pathways. We now count 20 reported cellular binding partners of CagA, which represents the highest quantitiy among all yet known virulence-associated effector proteins in the microbial world. This complexity generates a highly remarkable and puzzling scenario. In addition, the first crystal structure of CagA provided us with new information on the function of this important virulence determinant. Here we review the recent advances in characterizing the multiple binding signaling activities of CagA. Injected CagA can act as a 'master key' that evolved the ability to highjack multiple host cell signalling cascades, which include the induction of membrane dynamics, actin-cytoskeletal rearrangements and the disruption of cell-to-cell junctions as well as proliferative, pro-inflammatory and anti-apoptotic nuclear responses. The discovery that different pathogens use this common strategy to subvert host cell functions suggests that more examples will emerge soon.
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Hug I, Couturier MR, Rooker MM, Taylor DE, Stein M, Feldman MF. Helicobacter pylori lipopolysaccharide is synthesized via a novel pathway with an evolutionary connection to protein N-glycosylation. PLoS Pathog 2010; 6:e1000819. [PMID: 20333251 PMCID: PMC2841628 DOI: 10.1371/journal.ppat.1000819] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 02/09/2010] [Indexed: 01/25/2023] Open
Abstract
Lipopolysaccharide (LPS) is a major component on the surface of Gram negative bacteria and is composed of lipid A-core and the O antigen polysaccharide. O polysaccharides of the gastric pathogen Helicobacter pylori contain Lewis antigens, mimicking glycan structures produced by human cells. The interaction of Lewis antigens with human dendritic cells induces a modulation of the immune response, contributing to the H. pylori virulence. The amount and position of Lewis antigens in the LPS varies among H. pylori isolates, indicating an adaptation to the host. In contrast to most bacteria, the genes for H. pylori O antigen biosynthesis are spread throughout the chromosome, which likely contributed to the fact that the LPS assembly pathway remained uncharacterized. In this study, two enzymes typically involved in LPS biosynthesis were found encoded in the H. pylori genome; the initiating glycosyltransferase WecA, and the O antigen ligase WaaL. Fluorescence microscopy and analysis of LPS from H. pylori mutants revealed that WecA and WaaL are involved in LPS production. Activity of WecA was additionally demonstrated with complementation experiments in Escherichia coli. WaaL ligase activity was shown in vitro. Analysis of the H. pylori genome failed to detect a flippase typically involved in O antigen synthesis. Instead, we identified a homolog of a flippase involved in protein N-glycosylation in other bacteria, although this pathway is not present in H. pylori. This flippase named Wzk was essential for O antigen display in H. pylori and was able to transport various glycans in E. coli. Whereas the O antigen mutants showed normal swimming motility and injection of the toxin CagA into host cells, the uptake of DNA seemed to be affected. We conclude that H. pylori uses a novel LPS biosynthetic pathway, evolutionarily connected to bacterial protein N-glycosylation. Bacterial surfaces are decorated with glycans. The human stomach pathogen Helicobacter pylori exposes lipopolysaccharide (LPS) containing Lewis antigens that mimic human glycan structures. H. pylori alters its Lewis antigen display in adaptation to the individual host. Lewis antigens can interact with human dendritic cells, thereby inducing a suppression of the immune response and facilitating a chronic H. pylori infection. Whereas three general LPS biosynthesis pathways are known, the route of LPS assembly in H. pylori remained to be elucidated. We identified and characterized two components of the H. pylori LPS pathway, WecA and WaaL, which demonstrated that, as in other bacteria, the glycan is initially assembled onto a polyprenoid lipid carrier. This intermediate then has to cross a membrane barrier, requiring specialized translocases. H. pylori does not employ a translocase from common LPS pathways. We show that instead H. pylori uses a translocase named Wzk, which is involved in protein N-glycosylation in other bacteria. Wzk was able to translocate various glycan structures. The identification of Wzk as the H. pylori translocase involved in LPS biosynthesis indicates an evolutionary connection between LPS and glycoprotein biosynthesis pathways.
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Affiliation(s)
- Isabelle Hug
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Marc R. Couturier
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Michelle M. Rooker
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Diane E. Taylor
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Markus Stein
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Mario F. Feldman
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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Alvarez-Martinez CE, Christie PJ. Biological diversity of prokaryotic type IV secretion systems. Microbiol Mol Biol Rev 2009; 73:775-808. [PMID: 19946141 PMCID: PMC2786583 DOI: 10.1128/mmbr.00023-09] [Citation(s) in RCA: 524] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Type IV secretion systems (T4SS) translocate DNA and protein substrates across prokaryotic cell envelopes generally by a mechanism requiring direct contact with a target cell. Three types of T4SS have been described: (i) conjugation systems, operationally defined as machines that translocate DNA substrates intercellularly by a contact-dependent process; (ii) effector translocator systems, functioning to deliver proteins or other macromolecules to eukaryotic target cells; and (iii) DNA release/uptake systems, which translocate DNA to or from the extracellular milieu. Studies of a few paradigmatic systems, notably the conjugation systems of plasmids F, R388, RP4, and pKM101 and the Agrobacterium tumefaciens VirB/VirD4 system, have supplied important insights into the structure, function, and mechanism of action of type IV secretion machines. Information on these systems is updated, with emphasis on recent exciting structural advances. An underappreciated feature of T4SS, most notably of the conjugation subfamily, is that they are widely distributed among many species of gram-negative and -positive bacteria, wall-less bacteria, and the Archaea. Conjugation-mediated lateral gene transfer has shaped the genomes of most if not all prokaryotes over evolutionary time and also contributed in the short term to the dissemination of antibiotic resistance and other virulence traits among medically important pathogens. How have these machines adapted to function across envelopes of distantly related microorganisms? A survey of T4SS functioning in phylogenetically diverse species highlights the biological complexity of these translocation systems and identifies common mechanistic themes as well as novel adaptations for specialized purposes relating to the modulation of the donor-target cell interaction.
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Affiliation(s)
- Cristina E. Alvarez-Martinez
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin, Houston, Texas 77030
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin, Houston, Texas 77030
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Cag3 is a novel essential component of the Helicobacter pylori Cag type IV secretion system outer membrane subcomplex. J Bacteriol 2009; 191:7343-52. [PMID: 19801411 DOI: 10.1128/jb.00946-09] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Helicobacter pylori strains harboring the cag pathogenicity island (PAI) have been associated with more severe gastric disease in infected humans. The cag PAI encodes a type IV secretion (T4S) system required for CagA translocation into host cells as well as induction of proinflammatory cytokines, such as interleukin-8 (IL-8). cag PAI genes sharing sequence similarity with T4S components from other bacteria are essential for Cag T4S function. Other cag PAI-encoded genes are also essential for Cag T4S, but lack of sequence-based or structural similarity with genes in existing databases has precluded a functional assignment for the encoded proteins. We have studied the role of one such protein, Cag3 (HP0522), in Cag T4S and determined Cag3 subcellular localization and protein interactions. Cag3 is membrane associated and copurifies with predicted inner and outer membrane Cag T4S components that are essential for Cag T4S as well as putative accessory factors. Coimmunoprecipitation and cross-linking experiments revealed specific interactions with HpVirB7 and CagM, suggesting Cag3 is a new component of the Cag T4S outer membrane subcomplex. Finally, lack of Cag3 lowers HpVirB7 steady-state levels, further indicating Cag3 makes a subcomplex with this protein.
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Fischer W, Prassl S, Haas R. Virulence Mechanisms and Persistence Strategies of the Human Gastric Pathogen Helicobacter pylori. Curr Top Microbiol Immunol 2009; 337:129-71. [DOI: 10.1007/978-3-642-01846-6_5] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Angelini A, Tosi T, Mas P, Acajjaoui S, Zanotti G, Terradot L, Hart DJ. Expression of Helicobacter pylori CagA domains by library-based construct screening. FEBS J 2009; 276:816-24. [DOI: 10.1111/j.1742-4658.2008.06826.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Abstract
Helicobacter pylori infection is the most important risk factor in the development of non-cardia gastric adenocarcinoma; host genetic variability and dietary co-factors also modulate risk. Because most H. pylori infections do not cause cancer, H. pylori heterogeneity has been investigated to identify possible virulence factors. The strongest candidates are genes within the cag (cytotoxin-associated antigen) pathogenicity island, including the gene encoding the CagA protein, as well as polymorphic variation in the VacA vacuolating exotoxin and the blood group antigen binding adhesin BabA. Improved understanding of the pathogenesis of H. pylori-associated gastric cancer may improve risk stratification for prevention and therapy.
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Affiliation(s)
- Sicheng Wen
- Department of Medicine, Division of Gastroenterology, Rhode Island Hospital and Brown University, 593 Eddy Street, Providence, RI 02903, USA
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Wen S, Moss SF. Helicobacter pylori virulence factors in gastric carcinogenesis. Cancer Lett 2008; 282:1-8. [PMID: 19111390 DOI: 10.1016/j.canlet.2008.11.016] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 11/10/2008] [Accepted: 11/17/2008] [Indexed: 02/09/2023]
Abstract
Helicobacter pylori infection is the most important risk factor in the development of non-cardia gastric adenocarcinoma; host genetic variability and dietary co-factors also modulate risk. Because most H. pylori infections do not cause cancer, H. pylori heterogeneity has been investigated to identify possible virulence factors. The strongest candidates are genes within the cag (cytotoxin-associated antigen) pathogenicity island, including the gene encoding the CagA protein, as well as polymorphic variation in the VacA vacuolating exotoxin and the blood group antigen binding adhesin BabA. Improved understanding of the pathogenesis of H. pylori-associated gastric cancer may improve risk stratification for prevention and therapy.
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Affiliation(s)
- Sicheng Wen
- Department of Medicine, Division of Gastroenterology, Rhode Island Hospital and Brown University, 593 Eddy Street, Providence, RI 02903, USA
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The Helicobacter pylori CagD (HP0545, Cag24) protein is essential for CagA translocation and maximal induction of interleukin-8 secretion. J Mol Biol 2008; 386:204-17. [PMID: 19109970 DOI: 10.1016/j.jmb.2008.12.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 12/01/2008] [Accepted: 12/06/2008] [Indexed: 12/16/2022]
Abstract
Pathogenic strains of Helicobacter pylori use a type IV secretion system (T4SS) to deliver the toxin CagA into human host cells. The T4SS, along with the toxin itself, is coded into a genomic insert, which is termed the cag pathogenicity island. The cag pathogenicity island contains about 30 open-reading frames, for most of which the exact function is not well characterized or totally unknown. We have determined the crystal structure of one of the proteins coded by the cag genes, CagD, in two crystal forms. We show that the protein is a covalent dimer in which each monomer folds as a single domain that is composed of five beta-strands and three alpha-helices. Our data show that in addition to a cytosolic pool, CagD partially associates with the inner membrane, where it may be exposed to the periplasmic space. Furthermore, CagA tyrosine phosphorylation and interleukin-8 assays identified CagD as a crucial component of the T4SS that is involved in CagA translocation into host epithelial cells; however, it does not seem absolutely necessary for pilus assembly. We have also identified significant amounts of CagD in culture supernatants, which are not a result of general bacterial lysis. Since this localization was independent of the various tested cag mutants, our findings may indicate that CagD is released into the supernatant during host cell infection and then binds to the host cell surface or is incorporated in the pilus structure. Overall, our results suggest that CagD may serve as a unique multifunctional component of the T4SS that may be involved in CagA secretion at the inner membrane and may localize outside the bacteria to promote additional effects on the host cell.
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Juhas M, Crook DW, Hood DW. Type IV secretion systems: tools of bacterial horizontal gene transfer and virulence. Cell Microbiol 2008; 10:2377-86. [PMID: 18549454 PMCID: PMC2688673 DOI: 10.1111/j.1462-5822.2008.01187.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Type IV secretion systems (T4SSs) are multisubunit cell-envelope-spanning structures, ancestrally related to bacterial conjugation machines, which transfer proteins and nucleoprotein complexes across membranes. T4SSs mediate horizontal gene transfer, thus contributing to genome plasticity and the evolution of pathogens through dissemination of antibiotic resistance and virulence genes. Moreover, T4SSs are also used for the delivery of bacterial effector proteins across the bacterial membrane and the plasmatic membrane of eukaryotic host cell, thus contributing directly to pathogenicity. T4SSs are usually encoded by multiple genes organized into a single functional unit. Based on a number of features, the organization of genetic determinants, shared homologies and evolutionary relationships, T4SSs have been divided into several groups. Type F and P (type IVA) T4SSs resembling the archetypal VirB/VirD4 system of Agrobacterium tumefaciens are considered to be the paradigm of type IV secretion, while type I (type IVB) T4SSs are found in intracellular bacterial pathogens, Legionella pneumophila and Coxiella burnetii. Several novel T4SSs have been identified recently and their functions await investigation. The most recently described GI type T4SSs play a key role in the horizontal transfer of a wide variety of genomic islands derived from a broad spectrum of bacterial strains.
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Affiliation(s)
- Mario Juhas
- Clinical Microbiology and Infectious Diseases, Nuffield Department of Clinical Laboratory Sciences, University of Oxford, Oxford OX3 9DU, UK.
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