scholarly journals Roles of the plasticity regions of Helicobacter pylori in gastroduodenal pathogenesis

2008 ◽  
Vol 57 (5) ◽  
pp. 545-553 ◽  
Author(s):  
Yoshio Yamaoka
Keyword(s):  
Helicobacter Pylori ◽  
Virulence Genes ◽  
Type Iv Secretion ◽  
Phase Variable ◽  
Duodenal Ulcers ◽  
Gastric Cancers ◽  
Type Iv ◽  
Plasticity Region ◽  
Increased Risk ◽  
H Pylori

Putative virulence genes of Helicobacter pylori are generally classified into three categories: strain-specific genes, phase-variable genes and genes with variable structures/genotypes. Among these, there has recently been considerable interest in strain-specific genes found outside of the cag pathogenicity island, especially genes in the plasticity regions. Nearly half of the strain-specific genes of H. pylori are located in the plasticity regions in strains 26695 and J99. Strain HPAG1, however, seems to lack a typical plasticity region; instead it has 43 HPAG1-specific genes which are either undetectable or incompletely represented in the genomes of strains 26695 and J99. Recent studies showed that certain genes or combination of genes in this region may play important roles in the pathogenesis of H. pylori-associated gastroduodenal diseases. Most previous studies have focused on the plasticity region in strain J99 (jhp0914–jhp0961) and the jhp0947 gene and the duodenal ulcer promoting (dupA) gene are good candidate markers for gastroduodenal diseases although there are some paradoxical findings. The jhp0947 gene is reported to be associated with an increased risk of both duodenal ulcers and gastric cancers, whereas the dupA gene, which encompasses jhp0917 and jhp0918, is reported to be associated with an increased risk of duodenal ulcers and protection against gastric cancers. In addition, recent studies showed that approximately 10–30 % of clinical isolates possess a 16.3 kb type IV secretion apparatus (tfs3) in the plasticity region. Studies on the plasticity region have only just begun, and further investigation is necessary to elucidate the roles of genes in this region in gastroduodenal pathogenesis.

scholarly journals In Situ Molecular Architecture of the Helicobacter pylori Cag Type IV Secretion System

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Bo Hu ◽  
Pratick Khara ◽  
Liqiang Song ◽  
Aung Soe Lin ◽  
Arwen E. Frick-Cheng ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Legionella Pneumophila ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Content Type ◽  
Membrane Complex ◽  
Type Iv ◽  
Increased Risk ◽  
H Pylori

ABSTRACT Helicobacter pylori colonizes about half of humans worldwide, and its presence in the gastric mucosa is associated with an increased risk of gastric adenocarcinoma, gastric lymphoma, and peptic ulcer disease. H. pylori strains carrying the cag pathogenicity island (cagPAI) are associated with increased risk of disease progression. The cagPAI encodes the Cag type IV secretion system (CagT4SS), which delivers the CagA oncoprotein and other effector molecules into human gastric epithelial cells. We visualized structures of native and mutant CagT4SS machines on the H. pylori cell envelope by cryoelectron tomography. Individual H. pylori cells contain multiple CagT4SS nanomachines, each composed of a wheel-shaped outer membrane complex (OMC) with 14-fold symmetry and an inner membrane complex (IMC) with 6-fold symmetry. CagX, CagY, and CagM are required for assembly of the OMC, whereas strains lacking Cag3 and CagT produce outer membrane complexes lacking peripheral components. The IMC, which has never been visualized in detail, is configured as six tiers in cross-section view and three concentric rings surrounding a central channel in end-on view. The IMC contains three T4SS ATPases: (i) VirB4-like CagE, arranged as a hexamer of dimers at the channel entrance; (ii) a hexamer of VirB11-like Cagα, docked at the base of the CagE hexamer; and (iii) VirD4-like Cagβ and other unspecified Cag subunits, associated with the stacked CagE/Cagα complex and forming the outermost rings. The CagT4SS and recently solved Legionella pneumophila Dot/Icm system comprise new structural prototypes for the T4SS superfamily. IMPORTANCE Bacterial type IV secretion systems (T4SSs) have been phylogenetically grouped into two subfamilies. The T4ASSs, represented by the Agrobacterium tumefaciens VirB/VirD4T4SS, include “minimized” machines assembled from 12 VirB- and VirD4-like subunits and compositionally larger systems such as the Helicobacter pylori CagT4SS. T4BSSs encompass systems closely related in subunit composition to the Legionella pneumophila Dot/IcmT4SS. Here, we present structures of native and mutant H. pylori Cag machines determined by in situ cryoelectron tomography. We identify distinct outer and inner membrane complexes and, for the first time, visualize structural contributions of all three “signature” ATPases of T4SSs at the cytoplasmic entrance of the translocation channel. Despite their evolutionary divergence, the CagT4SS aligns structurally much more closely to the Dot/IcmT4SS than an available VirB/VirD4 subcomplex. Our findings highlight the diversity of T4SSs and suggest a structural classification scheme in which T4SSs are grouped as minimized VirB/VirD4-like or larger Cag-like and Dot/Icm-like systems.

scholarly journals The organization of Helicobacter pylori cag-pathogenicity island (cagPAI) genes in multiracial population with histopathological changes of gastric mucosa

2019 ◽  
Author(s):  
Alfizah Hanafiah ◽  
Shaza Azlin Razak ◽  
Hui-min Neoh ◽  
Noraziah Mohamad Zin ◽  
Bruno S. Lopes
Keyword(s):  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Pathogenicity Island ◽  
Type Iv Secretion ◽  
Virulence Determinants ◽  
Gastric Diseases ◽  
Cag Pathogenicity Island ◽  
Type Iv ◽  
Inflammatory Score ◽  
H Pylori

Abstract Background: Helicobacter pylori is a Gram-negative bacillus that colonises only the mucus layer of the human stomach and is implicated in gastric diseases. Virulent H. pylori harbouring cag-pathogenicity island (cagPAI) which encodes genes for type IV secretion system (T4SS) and CagA protein is one of the major virulence determinants involved in disease development. We examined the entire cagPAI genes in 95 H. pylori isolates from a multiracial population and examined the intactness of cagPAI region with histopathological scores of the gastric mucosa. Results: 95.8% of H. pylori isolates were cagPAI-positive with 23.2% having an intact cagPAI, whereas 72.6% had a partial/rearranged cagPAI. In our study, cag2 and cag4 were found to be significantly higher in H. pylori isolated from Malays, whereas cag4 was predominant in Chinese isolates. We also detected cag24 in significantly high proportion in isolates from the Malays and the Indians compared to the Chinese isolates. The intactness of cagPAI region showed an association with histopathological scores of the gastric mucosa. Significant association was observed between H. pylori harbouring partial cagPAI and higher density of H. pylori and neutrophil activity, whereas strains which lacked cagPAI was associated with higher inflammatory score. Conclusions: The screening of the entire cagPAI genes provides an accurate overview of the cagPAI organisation in H. pylori isolates in a multiracial population. The genotypes of H. pylori strains with various cagPAI rearrangement associated with patients’ ethnicities and histopathological scores might contribute to the pathogenesis of H. pylori infection in a multi-ethnic population.

scholarly journals The Helicobacter pylori Autotransporter ImaA Tempers the Bacterium's Interaction with α5β1 Integrin

2016 ◽  
Vol 85 (1) ◽  
Author(s):  
William E. Sause ◽  
Daniela Keilberg ◽  
Soufiane Aboulhouda ◽  
Karen M. Ottemann
Keyword(s):  
Helicobacter Pylori ◽  
Host Cell ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Wild Type ◽  
Content Type ◽  
Type Iv ◽  
H Pylori ◽  
Α5β1 Integrin ◽  
Cell Interface

ABSTRACT The human pathogen Helicobacter pylori uses the host receptor α5β1 integrin to trigger inflammation in host cells via its cag pathogenicity island (cag PAI) type IV secretion system (T4SS). Here, we report that the H. pylori ImaA protein (HP0289) decreases the action of the cag PAI T4SS via tempering the bacterium's interaction with α5β1 integrin. Previously, imaA-null mutants were found to induce an elevated inflammatory response that was dependent on the cag PAI T4SS; here we extend those findings to show that the elevated response is independent of the CagA effector protein. To understand how ImaA could be affecting cag PAI T4SS activity at the host cell interface, we utilized the Phyre structural threading program and found that ImaA has a region with remote homology to bacterial integrin-binding proteins. This region was required for ImaA function. Unexpectedly, we observed that imaA mutants bound higher levels of α5β1 integrin than wild-type H. pylori, an outcome that required the predicted integrin-binding homology region of ImaA. Lastly, we report that ImaA directly affected the amount of host cell β1 integrin but not other cellular integrins. Our results thus suggest a model in which H. pylori employs ImaA to regulate interactions between integrin and the T4SS and thus alter the host inflammatory strength.

scholarly journals Protein-Protein Interactions among Helicobacter pylori Cag Proteins

2006 ◽  
Vol 188 (13) ◽  
pp. 4787-4800 ◽  
Author(s):  
Valerie J. Busler ◽  
Victor J. Torres ◽  
Mark S. McClain ◽  
Oscar Tirado ◽  
David B. Friedman ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Protein Interactions ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Protein Protein Interactions ◽  
Chromosomal Dna ◽  
2D Dige ◽  
Type Iv ◽  
H Pylori

ABSTRACT Many Helicobacter pylori isolates contain a 40-kb region of chromosomal DNA known as the cag pathogenicity island (PAI). The risk for development of gastric cancer or peptic ulcer disease is higher among humans infected with cag PAI-positive H. pylori strains than among those infected with cag PAI-negative strains. The cag PAI encodes a type IV secretion system that translocates CagA into gastric epithelial cells. To identify Cag proteins that are expressed by H. pylori during growth in vitro, we compared the proteomes of a wild-type H. pylori strain and an isogenic cag PAI deletion mutant using two-dimensional difference gel electrophoresis (2D-DIGE) in multiple pH ranges. Seven Cag proteins were identified by this approach. We then used a yeast two-hybrid system to detect potential protein-protein interactions among 14 Cag proteins. One heterotypic interaction (CagY/7 with CagX/8) and two homotypic interactions (involving H. pylori VirB11/ATPase and Cag5) were similar to interactions previously reported to occur among homologous components of the Agrobacterium tumefaciens type IV secretion system. Other interactions involved Cag proteins that do not have known homologues in other bacterial species. Biochemical analysis confirmed selected interactions involving five of the proteins that were identified by 2D-DIGE. Protein-protein interactions among Cag proteins are likely to have an important role in the assembly of the H. pylori type IV secretion apparatus.

scholarly journals Molecular and Structural Analysis of the Helicobacter pylori cag Type IV Secretion System Core Complex

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Arwen E. Frick-Cheng ◽  
Tasia M. Pyburn ◽  
Bradley J. Voss ◽  
W. Hayes McDonald ◽  
Melanie D. Ohi ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Bacterial Species ◽  
Secretion System ◽  
Effector Proteins ◽  
Type Iv Secretion ◽  
Secretion Systems ◽  
Core Complex ◽  
Type Iv ◽  
Membrane Spanning ◽  
H Pylori

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 Δ cag3 or Δ cagT 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. IMPORTANCE 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.

scholarly journals Prediction of Epitopes in the Proteome of Helicobacter pylori

2018 ◽  
Vol 10 (7) ◽  
pp. 148 ◽  
Author(s):  
Elkin Navarro-Quiroz ◽  
Roberto Navarro-Quiroz ◽  
Pierine España-Puccini ◽  
José Luis Villarreal ◽  
Anderson Díaz Perez ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
World Health ◽  
Phase Variable ◽  
Human Pathogens ◽  
Web Tool ◽  
Group I ◽  
Increased Risk ◽  
Risk Of Disease ◽  
H Pylori ◽  
Health Organization

Helicobacter pylori (H. pylori) is classified by the World Health Organization (WHO) as a group I carcinogen and is one of the most efficient human pathogens with over half of the world's population colonized by this gram-negative spiral bacterium. H. pylori can cause a chronic infection in the stomach during early childhood that persists throughout life due to diverse mechanisms of immune response evasion. H. pylori has several factors strongly associated with increased risk of disease such as toxins, adhesins, and chemoattractants, some of which are highly polymorphic, phase variable, and have different functions. Conventional treatments involve the use of antibiotics. However, treatment frequently fails due to the resistance H. pylori has progressively developed to antibiotics. This creates the need for different treatments made possible by identifying new therapeutic targets in the pathogen’s genome.The purpose of this study was an in silico prediction of T- and B- epitopes in H. pylori proteins. Twenty-two external membrane proteins from H. pylori Strain 26695 (accession number NC_000915) were identified using the web tool Vaxign (http://www.violinet.org/vaxign/). A total of one-hundred epitopes (60 class I epitopes and 40 class II epitopes) that could be used to develop novel non-antibiotics drugs for an H. pylori infection were predicted.

scholarly journals Analysis of Cell Type-Specific Responses Mediated by the Type IV Secretion System of Helicobacter pylori

2005 ◽  
Vol 73 (8) ◽  
pp. 4643-4652 ◽  
Author(s):  
Bianca Bauer ◽  
Stefan Moese ◽  
Sina Bartfeld ◽  
Thomas F. Meyer ◽  
Matthias Selbach
Keyword(s):  
Helicobacter Pylori ◽  
Host Cell ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv ◽  
Host Cell Proteins ◽  
Mammalian Cell Lines ◽  
Host Cell Factors ◽  
H Pylori

ABSTRACT Helicobacter pylori persistently infects the human stomach and can cause gastritis, gastric ulceration, and gastric cancer. The type IV secretion system (TFSS) of virulent H. pylori strains translocates the CagA protein, inducing the dephosphorylation of host cell proteins and leading to changes in the morphology or shape of AGS gastric epithelial cells. Furthermore, the TFSS is involved in the induction of proinflammatory cytokines. While the H. pylori genes required for TFSS function have been investigated systematically, little is known about possible host cell factors involved. We infected 19 different mammalian cell lines individually with H. pylori and analyzed CagA translocation, dephosphorylation of host cell proteins, chemokine secretion (interleukin-8 and macrophage inflammatory protein 2), and changes in cellular phenotypes. Our results demonstrate that not only bacterial but also host cell factors determine the cellular response to infection. The identification of such unknown host cell factors will add to our understanding of host-pathogen interactions and might help in the development of new therapeutic strategies.

scholarly journals T4SS-dependent TLR5 activation by Helicobacter pylori infection

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Suneesh Kumar Pachathundikandi ◽  
Nicole Tegtmeyer ◽  
Isabelle Catherine Arnold ◽  
Judith Lind ◽  
Matthias Neddermann ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Pathogenic Bacteria ◽  
Type Iv Secretion ◽  
Downstream Signaling ◽  
Type Iv ◽  
Efficient Control ◽  
H Pylori ◽  
Highly Virulent

AbstractToll-like receptor TLR5 recognizes a conserved domain, termed D1, that is present in flagellins of several pathogenic bacteria but not in Helicobacter pylori. Highly virulent H. pylori strains possess a type IV secretion system (T4SS) for delivery of virulence factors into gastric epithelial cells. Here, we show that one of the H. pylori T4SS components, protein CagL, can act as a flagellin-independent TLR5 activator. CagL contains a D1-like motif that mediates adherence to TLR5+ epithelial cells, TLR5 activation, and downstream signaling in vitro. TLR5 expression is associated with H. pylori infection and gastric lesions in human biopsies. Using Tlr5-knockout and wild-type mice, we show that TLR5 is important for efficient control of H. pylori infection. Our results indicate that CagL, by activating TLR5, may modulate immune responses to H. pylori.

scholarly journals Precancerous Gastric Lesions with Helicobacter pylori vacA+/babA2+/oipA+ Genotype Increase the Risk of Gastric Cancer

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Theeraya Simawaranon Bartpho ◽  
Wareeporn Wattanawongdon ◽  
Taweesak Tongtawee ◽  
Chatchanok Paoin ◽  
Kokiet Kangwantas ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Clinical Outcomes ◽  
Chronic Gastritis ◽  
Virulence Genes ◽  
Gastric Lesions ◽  
Precancerous Gastric Lesions ◽  
Increased Risk ◽  
H Pylori ◽  
Gastric Cancer Patients

Objective. The clinical outcomes of gastric diseases such as chronic gastritis, peptic ulcer, and gastric cancer have been attributed to the interplay of virulence factors of Helicobacter pylori (H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of cagA, vacA, iceA2, babA2, and oipA genes and their association with clinical outcomes. Methods. Chronic gastritis, atrophic gastritis, and intestinal metaplasia specimens were obtained from patients who underwent endoscopy and surgical resection between January 2017 and December 2018; specimens from gastric cancer patients treated between January 2014 and December 2018 were also added. H. pylori infection and virulence genes (cagA, vacA, iceA2, babA2, and oipA) were determined using real-time PCR. The association between H. pylori genotypes and clinical outcomes were evaluated using multivariate regression model analysis. The overall survival of gastric cancer patients was compared between genotype combinations. Results. H. pylori was positive in 166 patients with chronic gastritis, precancerous gastric lesions, and gastric cancer. The genes vacA, babA2, and oipA were most prevalent in chronic gastritis (73%), precancerous gastric lesions (62%), and gastric cancer (91%), respectively. The vacA, babA2, and oipA genes were associated with increased risk of gastric cancer (OR = 1.23; 95% CI = 1.13–3.32; P=0.033, OR = 2.64; 95% CI = 1.44–4.82, P=0.024, and OR = 2.79; 95% CI = 1.58–5.41; P=0.031, respectively). Interestingly, H. pylori vacA+/babA2+/oipA+ genotype infection was associated with increased risk of gastric cancer (OR = 3.85, 95% CI = 1.67–5.77, P=0.014). Conclusion. In this present study, we reported on the virulence genes of H. pylori infection to reveal their association with increased risk of chronic gastritis, precancerous gastric lesions, and gastric cancer. Precancerous gastric lesions with H. pylori vacA+/babA2+/oipA+ genotype increased the risk of gastric cancer.

scholarly journals Functional Analysis of the Helicobacter pylori cag Pathogenicity Island Reveals Both VirD4-CagA-Dependent and VirD4-CagA-Independent Mechanisms

2002 ◽  
Vol 70 (2) ◽  
pp. 665-671 ◽  
Author(s):  
Matthias Selbach ◽  
Stefan Moese ◽  
Thomas F. Meyer ◽  
Steffen Backert
Keyword(s):  
Helicobacter Pylori ◽  
Gene Knockout ◽  
Shuttle Vector ◽  
Pathogenicity Island ◽  
Type Iv Secretion ◽  
Host Responses ◽  
Type Iv ◽  
Knockout Mutants ◽  
H Pylori ◽  
First Time

ABSTRACT The type IV secretion machinery encoded by the cag pathogenicity island (PAI) of Helicobacter pylori has been implicated in a series of host responses during infection. Here, we analyzed the function of 12 cag PAI genes from both cag I and cag II loci, including the complete virB/D complex (virB4, virB7, virB8, virB9, virB10, virB11, and virD4). We monitored interleukin-8 (IL-8) secretion, CagA translocation and tyrosine phosphorylation, and induction of a scattering (“hummingbird”) phenotype upon H. pylori infection of AGS gastric epithelial cells. For the first time, we have complemented individual cag PAI gene knockout mutants with their intact genes expressed from a shuttle vector and showed that complemented CagA and VirD4 restored wild-type function. Our results demonstrate that phenotypic changes and phosphorylation of CagA depended on all virB/D genes and several other genes of the cag PAI. Induction of IL-8 secretion depended largely on the same set of genes but was independent of CagA and VirD4. Thus, CagA translocation and induction of IL-8 secretion are regulated by VirD4-CagA-dependent and VirD4-CagA-independent mechanisms, respectively. The function of VirD4 as a possible adapter protein which guides CagA into the type IV secretion channel is presented in a model.

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