scholarly journals Maintenance of Type IV Secretion Function During Helicobacter pylori Infection in Mice

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. e03147-20
Author(s):  
Emma C. Skoog ◽  
Miriam E. Martin ◽  
Roberto M. Barrozo ◽  
Lori M. Hansen ◽  
Lucy P. Cai ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Murine Model ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Content Type ◽  
Biologically Relevant ◽  
Type Iv ◽  
H Pylori

ABSTRACTThe Helicobacter pylori type IV secretion system (T4SS) encoded on the cag pathogenicity island (cagPAI) secretes the CagA oncoprotein and other effectors into the gastric epithelium. During murine infection, T4SS function is lost in an immune-dependent manner, typically as a result of in-frame recombination in the middle repeat region of cagY, though single nucleotide polymorphisms (SNPs) in cagY or in other essential genes may also occur. Loss of T4SS function also occurs in gerbils, nonhuman primates, and humans, suggesting that it is biologically relevant and not simply an artifact of the murine model. Here, we sought to identify physiologically relevant conditions under which T4SS function is maintained in the murine model. We found that loss of H. pylori T4SS function in mice was blunted by systemic Salmonella coinfection and completely eliminated by dietary iron restriction. Both have epidemiologic parallels in humans, since H. pylori strains from individuals in developing countries, where iron deficiency and systemic infections are common, are also more often cagPAI+ than strains from developed countries. These results have implications for our fundamental understanding of the cagPAI and also provide experimental tools that permit the study of T4SS function in the murine model.IMPORTANCE The type IV secretion system (T4SS) is the major Helicobacter pylori virulence factor, though its function is lost during murine infection. Loss of function also occurs in gerbils and in humans, suggesting that it is biologically relevant, but the conditions under which T4SS regulation occurs are unknown. Here, we found that systemic coinfection with Salmonella and iron deprivation each promote retention of T4SS function. These results improve our understanding of the cag pathogenicity island (cagPAI) and provide experimental tools that permit the study of T4SS function in the murine model.

scholarly journals Genes Required for Assembly of Pili Associated with the Helicobacter pylori cag Type IV Secretion System

2014 ◽  
Vol 82 (8) ◽  
pp. 3457-3470 ◽  
Author(s):  
Elizabeth M. Johnson ◽  
Jennifer A. Gaddy ◽  
Bradley J. Voss ◽  
Ewa E. Hennig ◽  
Timothy L. Cover
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Gastric Epithelial Cells ◽  
Content Type ◽  
Type Iv ◽  
Pilus Biogenesis ◽  
H Pylori

ABSTRACTHelicobacter pyloricauses numerous alterations in gastric epithelial cells through processes that are dependent on activity of thecagtype IV secretion system (T4SS). Filamentous structures termed “pili” have been visualized at the interface betweenH. pyloriand gastric epithelial cells, and previous studies suggested that pilus formation is dependent on the presence of thecagpathogenicity island (PAI). Thus far, there has been relatively little effort to identify specific genes that are required for pilus formation, and the role of pili in T4SS function is unclear. In this study, we selected 7 genes in thecagPAI that are known to be required for T4SS function and investigated whether these genes were required for pilus formation.cagT,cagX,cagV,cagM, andcag3mutants were defective in both T4SS function and pilus formation; complemented mutants regained T4SS function and the capacity for pilus formation.cagYandcagCmutants were defective in T4SS function but retained the capacity for pilus formation. These results define a set ofcagPAI genes that are required for both pilus biogenesis and T4SS function and reveal that these processes can be uncoupled in specific mutant strains.

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 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.

Crystal Structure of CagZ, a Protein from the Helicobacter pylori Pathogenicity Island that Encodes for a Type IV Secretion System

2004 ◽  
Vol 340 (4) ◽  
pp. 881-889 ◽  
Author(s):  
Laura Cendron ◽  
Anke Seydel ◽  
Alessandro Angelini ◽  
Roberto Battistutta ◽  
Giuseppe Zanotti
Keyword(s):  
Crystal Structure ◽  
Helicobacter Pylori ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv

scholarly journals ALPK1 and TIFA dependent innate immune response triggered by the Helicobacter pylori type IV secretion system

2017 ◽  
Author(s):  
Stephanie Zimmermann ◽  
Lennart Pfannkuch ◽  
Munir A. Al-Zeer ◽  
Sina Bartfeld ◽  
Manuel Koch ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Protein Translocation ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Innate Immune ◽  
Host Cells ◽  
Cell Contact ◽  
Type Iv Secretion System ◽  
Type Iv ◽  
H Pylori

SummaryActivation of transcription factor NF-κB is a hallmark of infection with the gastric pathogen Helicobacter pylori and associated with inflammation and carcinogenesis. Genome-wide RNAi screening revealed numerous hits involved in H. pylori-, but not IL-1β- and TNF-α- dependent NF-κB regulation. Pathway analysis including CRISPR/Cas9-knockout and recombinant protein technology, immunofluorescence microscopy, immunoblotting, mass spectrometry and mutant H. pylori strains, identified the H. pylori metabolite D-glycero-β-D-manno-heptose 1,7-bisphosphate (βHBP) as a cagPAI type IV secretion system (T4SS)-dependent effector of NF-κB activation in infected cells. Upon pathogen-host cell contact, TIFA forms large complexes (TIFAsomes) including interacting host factors, such as TRAF2. NF-κB activation, TIFA phosphorylation as well as TIFAsome formation depended on a functional ALPK1 kinase, highlighting the ALPK1-TIFA axis as core of a novel innate immune pathway. ALPK1-TIFA-mediated NF-κB activation was independent of CagA protein translocation, indicating that CagA translocation and HBP delivery to host cells are distinct features of the pathogen’s T4SS.

scholarly journals CagY-Dependent Regulation of Type IV Secretion inHelicobacter pyloriIs Associated with Alterations in Integrin Binding

mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Emma C. Skoog ◽  
Vasilios A. Morikis ◽  
Miriam E. Martin ◽  
Greg A. Foster ◽  
Lucy P. Cai ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Inflammatory Response ◽  
Persistent Infection ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Content Type ◽  
Type Iv ◽  
H Pylori ◽  
Host Inflammatory Response

ABSTRACTStrains ofHelicobacter pylorithat cause ulcer or gastric cancer typically express a type IV secretion system (T4SS) encoded by thecagpathogenicity island (cagPAI). CagY is an ortholog of VirB10 that, unlike other VirB10 orthologs, has a large middle repeat region (MRR) with extensive repetitive sequence motifs, which undergo CD4+T cell-dependent recombination during infection of mice. Recombination in the CagY MRR reduces T4SS function, diminishes the host inflammatory response, and enables the bacteria to colonize at a higher density. Since CagY is known to bind human α5β1integrin, we tested the hypothesis that recombination in the CagY MRR regulates T4SS function by modulating binding to α5β1integrin. Using a cell-free microfluidic assay, we found thatH. pyloribinding to α5β1integrin under shear flow is dependent on the CagY MRR, but independent of the presence of the T4SS pili, which are only formed whenH. pyloriis in contact with host cells. Similarly, expression of CagY in the absence of other T4SS genes was necessary and sufficient for whole bacterial cell binding to α5β1integrin. Bacteria with variantcagYalleles that reduced T4SS function showed comparable reduction in binding to α5β1integrin, although CagY was still expressed on the bacterial surface. We speculate thatcagY-dependent modulation ofH. pyloriT4SS function is mediated by alterations in binding to α5β1integrin, which in turn regulates the host inflammatory response so as to maximize persistent infection.IMPORTANCEInfection withH. pylorican cause peptic ulcers and is the most important risk factor for gastric cancer, the third most common cause of cancer death worldwide. The majorH. pylorivirulence factor that determines whether infection causes disease or asymptomatic colonization is the type IV secretion system (T4SS), a sort of molecular syringe that injects bacterial products into gastric epithelial cells and alters host cell physiology. We previously showed that recombination in CagY, an essential T4SS component, modulates the function of the T4SS. Here we found that these recombination events produce parallel changes in specific binding to α5β1integrin, a host cell receptor that is essential for T4SS-dependent translocation of bacterial effectors. We propose that CagY-dependent binding to α5β1integrin acts like a molecular rheostat that alters T4SS function and modulates the host immune response to promote persistent infection.

scholarly journals Cryo-EM reveals species-specific components within the Helicobacter pylori Cag type IV secretion system core complex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Michael J Sheedlo ◽  
Jeong Min Chung ◽  
Neha Sawhney ◽  
Clarissa L Durie ◽  
Timothy L Cover ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Molar Ratio ◽  
Type Iv Secretion System ◽  
Core Complex ◽  
Type Iv ◽  
H Pylori ◽  
Species Specific

The pathogenesis of Helicobacter pylori-associated gastric cancer is dependent on delivery of CagA into host cells through a type IV secretion system (T4SS). The H. pylori Cag T4SS includes a large membrane-spanning core complex containing five proteins, organized into an outer membrane cap (OMC), a periplasmic ring (PR) and a stalk. Here, we report cryo-EM reconstructions of a core complex lacking Cag3 and an improved map of the wild-type complex. We define the structures of two unique species-specific components (Cag3 and CagM) and show that Cag3 is structurally similar to CagT. Unexpectedly, components of the OMC are organized in a 1:1:2:2:5 molar ratio (CagY:CagX:CagT:CagM:Cag3). CagX and CagY are components of both the OMC and the PR and bridge the symmetry mismatch between these regions. These results reveal that assembly of the H. pylori T4SS core complex is dependent on incorporation of interwoven species-specific components.

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.

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