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Mohammed HS, Ibrahim MH, Abdel-Aziz MM, Ghareeb MA. Anti- Helicobacter pylori, anti-biofilm activity, and molecular docking study of citropten, bergapten, and its positional isomer isolated from Citrus sinensis L. leaves. Heliyon 2024; 10:e25232. [PMID: 38352786 PMCID: PMC10861955 DOI: 10.1016/j.heliyon.2024.e25232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 02/16/2024] Open
Abstract
Introduction Citrus sinensis L. is a candidate plant with promising antimicrobial potential. In the current study, the phytochemical investigation of C. sinensis leaf extract led to the isolation of three coumarins, namely bergapten, xanthotoxin, and citropten. Methods The chemical structures of the isolated coumarins were elucidated using NMR and ESI-MS techniques. The total aqueous ethanol leaf extract and the isolated coumarins were evaluated for their antimicrobial effects against Helicobacter pylori using the MTT-micro-well dilution method and its anti-biofilm activity using MBEC assay, as compared to clarithromycin. Results The results showed that citropten scored the lowest MIC value at 3.9 μg/mL and completely inhibited the planktonic growth of H. pylori. In addition, it completely suppressed H. pylori biofilm at 31.25 μg/mL. These findings have been supported by molecular docking studies on the active sites of the H. pylori inosine 5'-monophosphate dehydrogenase (HpIMPDH) model and the urease enzyme, showing a strong binding affinity of citropten to HpIMPDH with seven hydrogen bonds and a binding energy of -6.9 kcal/mol. Xanthotoxin and bergapten showed good docking scores, both at -6.5 kcal/mol for HpIMPDH, with each having four hydrogen bondings. Furthermore, xanthotoxin showed many hydrophobic interactions, while bergapten formed one Pi-anion interaction. Concerning docking in the urease enzyme, the compounds showed mild to moderate binding affinities as compared to the ligand. Thus, based on docking results and good binding scores observed with the HpIMPDH active site, an in-vitro HpIMPDH inhibition assay was done for the compounds. Citropten showed the most promising inhibitory activity with an IC50 value of 2.4 μM. Conclusion: The present study demonstrates that C. sinensis L. leaves are a good source for supplying coumarins that can act as naturally effective anti-H. pylori agents.
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Affiliation(s)
- Hala Sh Mohammed
- Department of Pharmacognosy and Medicinal Plants, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, 11311, Egypt
| | - Mona H. Ibrahim
- Pharmaceutical Medicinal Chemistry and Drug Design Department, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, 11311, Egypt
| | - Marwa M. Abdel-Aziz
- The Regional Centre for Mycology and Biotechnology, Al-Azhar University, Cairo, Egypt
| | - Mosad A. Ghareeb
- Medicinal Chemistry Department, Theodor Bilharz Research Institute, Kornaish El-Nile, Warrak El-Hadar, Imbaba, P.O. Box 30, Giza, 12411, Egypt
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Uberti AF, Callai-Silva N, Grahl MVC, Piovesan AR, Nachtigall EG, Furini CRG, Carlini CR. Helicobacter pylori Urease: Potential Contributions to Alzheimer’s Disease. Int J Mol Sci 2022; 23:ijms23063091. [PMID: 35328512 PMCID: PMC8949269 DOI: 10.3390/ijms23063091] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/24/2022] Open
Abstract
Alzheimer’s disease (AD) causes dementia and memory loss in the elderly. Deposits of beta-amyloid peptide and hyperphosphorylated tau protein are present in a brain with AD. A filtrate of Helicobacter pylori’s culture was previously found to induce hyperphosphorylation of tau in vivo, suggesting that bacterial exotoxins could permeate the blood–brain barrier and directly induce tau’s phosphorylation. H. pylori, which infects ~60% of the world population and causes gastritis and gastric cancer, produces a pro-inflammatory urease (HPU). Here, the neurotoxic potential of HPU was investigated in cultured cells and in rats. SH-SY5Y neuroblastoma cells exposed to HPU (50–300 nM) produced reactive oxygen species (ROS) and had an increased [Ca2+]i. HPU-treated BV-2 microglial cells produced ROS, cytokines IL-1β and TNF-α, and showed reduced viability. Rats received daily i.p., HPU (5 µg) for 7 days. Hyperphosphorylation of tau at Ser199, Thr205 and Ser396 sites, with no alterations in total tau or GSK-3β levels, and overexpression of Iba1, a marker of microglial activation, were seen in hippocampal homogenates. HPU was not detected in the brain homogenates. Behavioral tests were performed to assess cognitive impairments. Our findings support previous data suggesting an association between infection by H. pylori and tauopathies such as AD, possibly mediated by its urease.
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Affiliation(s)
- Augusto F. Uberti
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
| | - Natalia Callai-Silva
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
| | - Matheus V. C. Grahl
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
| | - Angela R. Piovesan
- Center of Biotechnology, Graduate Program in Cellular and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre CEP 91501-970, RS, Brazil;
| | - Eduarda G. Nachtigall
- Laboratory of Cognition and Memory Neurobiology, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Biomedical Gerontology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (E.G.N.); (C.R.G.F.)
| | - Cristiane R. G. Furini
- Laboratory of Cognition and Memory Neurobiology, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Biomedical Gerontology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (E.G.N.); (C.R.G.F.)
| | - Celia Regina Carlini
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
- Correspondence: ; Tel.: +55-51-3320-5986
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Gobert AP, Wilson KT. Induction and Regulation of the Innate Immune Response in Helicobacter pylori Infection. Cell Mol Gastroenterol Hepatol 2022; 13:1347-1363. [PMID: 35124288 PMCID: PMC8933844 DOI: 10.1016/j.jcmgh.2022.01.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 12/30/2022]
Abstract
Gastric cancer (GC) is the fifth most common cancer and the fourth most common cause of cancer-related death worldwide. The intestinal type of GC progresses from acute to chronic gastritis, multifocal atrophic gastritis, intestinal metaplasia, dysplasia, and carcinoma. Infection of the stomach by Helicobacter pylori, a Gram-negative bacterium that infects approximately 50% of the world's population, is the causal determinant that initiates the gastric inflammation and then disease progression. In this context, the induction of the innate immune response of gastric epithelial cells and myeloid cells by H. pylori effectors plays a critical role in the outcome of the infection. However, only 1% to 3% of infected patients develop gastric adenocarcinoma, emphasizing that other mechanisms regulate the localized non-specific response, including the gastric microbiota and genetic factors. This review summarizes studies describing the factors that induce and regulate the mucosal innate immune response during H. pylori infection.
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Affiliation(s)
- Alain P Gobert
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Nashville, Tennessee; Center for Mucosal Inflammation and Cancer, Nashville, Tennessee; Program in Cancer Biology, Nashville, Tennessee.
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Nashville, Tennessee; Center for Mucosal Inflammation and Cancer, Nashville, Tennessee; Program in Cancer Biology, Nashville, Tennessee; Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee; Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee.
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Lee L, Samardzic K, Wallach M, Frumkin LR, Mochly-Rosen D. Immunoglobulin Y for Potential Diagnostic and Therapeutic Applications in Infectious Diseases. Front Immunol 2021; 12:696003. [PMID: 34177963 PMCID: PMC8220206 DOI: 10.3389/fimmu.2021.696003] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 05/26/2021] [Indexed: 01/14/2023] Open
Abstract
Antiviral, antibacterial, and antiparasitic drugs and vaccines are essential to maintaining the health of humans and animals. Yet, their production can be slow and expensive, and efficacy lost once pathogens mount resistance. Chicken immunoglobulin Y (IgY) is a highly conserved homolog of human immunoglobulin G (IgG) that has shown benefits and a favorable safety profile, primarily in animal models of human infectious diseases. IgY is fast-acting, easy to produce, and low cost. IgY antibodies can readily be generated in large quantities with minimal environmental harm or infrastructure investment by using egg-laying hens. We summarize a variety of IgY uses, focusing on their potential for the detection, prevention, and treatment of human and animal infections.
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Affiliation(s)
- Lucia Lee
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, United States
| | - Kate Samardzic
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, United States
| | - Michael Wallach
- School of Life Sciences, University of Technology, Sydney, NSW, Australia
| | | | - Daria Mochly-Rosen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, United States
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Noncatalytic Antioxidant Role for Helicobacter pylori Urease. J Bacteriol 2018; 200:JB.00124-18. [PMID: 29866802 DOI: 10.1128/jb.00124-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/30/2018] [Indexed: 12/15/2022] Open
Abstract
The well-studied catalytic role of urease, the Ni-dependent conversion of urea into carbon dioxide and ammonia, has been shown to protect Helicobacter pylori against the low pH environment of the stomach lumen. We hypothesized that the abundantly expressed urease protein can play another noncatalytic role in combating oxidative stress via Met residue-mediated quenching of harmful oxidants. Three catalytically inactive urease mutant strains were constructed by single substitutions of Ni binding residues. The mutant versions synthesize normal levels of urease, and the altered versions retained all methionine residues. The three site-directed urease mutants were able to better withstand a hypochlorous acid (HOCl) challenge than a ΔureAB deletion strain. The capacity of purified urease to protect whole cells via oxidant quenching was assessed by adding urease enzyme to nongrowing HOCl-exposed cells. No wild-type cells were recovered with oxidant alone, whereas urease addition significantly aided viability. These results suggest that urease can protect H. pylori against oxidative damage and that the protective ability is distinct from the well-characterized catalytic role. To determine the capability of methionine sulfoxide reductase (Msr) to reduce oxidized Met residues in urease, purified H. pylori urease was exposed to HOCl and a previously described Msr peptide repair mixture was added. Of the 25 methionine residues in urease, 11 were subject to both oxidation and to Msr-mediated repair, as identified by mass spectrometry (MS) analysis; therefore, the oxidant-quenchable Met pool comprising urease can be recycled by the Msr repair system. Noncatalytic urease appears to play an important role in oxidant protection.IMPORTANCE Chronic Helicobacter pylori infection can lead to gastric ulcers and gastric cancers. The enzyme urease contributes to the survival of the bacterium in the harsh environment of the stomach by increasing the local pH. In addition to combating acid, H. pylori must survive host-produced reactive oxygen species to persist in the gastric mucosa. We describe a cyclic amino acid-based antioxidant role of urease, whereby oxidized methionine residues can be recycled by methionine sulfoxide reductase to again quench oxidants. This work expands our understanding of the role of an already acknowledged pathogen virulence factor and specifically expands our knowledge of H. pylori survival mechanisms.
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Zou W, Wang M, Yao D, Zhu Z, Sun W, Cai H, Chen X, Li F, Shen W, Barba FJ, Zhang W. Fluorescence and circular dichroism spectroscopy to understand the interactions between cyclodextrins and α-galactosidase from green coffee beans. FOOD BIOSCI 2017. [DOI: 10.1016/j.fbio.2017.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Macegoniuk K, Grela E, Palus J, Rudzińska-Szostak E, Grabowiecka A, Biernat M, Berlicki Ł. 1,2-Benzisoselenazol-3(2H)-one Derivatives As a New Class of Bacterial Urease Inhibitors. J Med Chem 2016; 59:8125-33. [DOI: 10.1021/acs.jmedchem.6b00986] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Katarzyna Macegoniuk
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Ewa Grela
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Jerzy Palus
- Department
of Organic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Ewa Rudzińska-Szostak
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Agnieszka Grabowiecka
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Monika Biernat
- Department
of Microbiology, Medical University of Wrocław, Tytusa Chałubińskiego
4, 50-368 Wrocław, Poland
| | - Łukasz Berlicki
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Lester J, Kichler S, Oickle B, Fairweather S, Oberc A, Chahal J, Ratnayake D, Creuzenet C. Characterization ofHelicobacter pylori HP0231 (DsbK): role in disulfide bond formation, redox homeostasis and production ofHelicobactercystein-rich protein HcpE. Mol Microbiol 2015; 96:110-33. [DOI: 10.1111/mmi.12923] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2015] [Indexed: 12/26/2022]
Affiliation(s)
- Jeffrey Lester
- Microbiology and Immunology; Western University; London N6A5C1 Canada
| | - Sari Kichler
- Microbiology and Immunology; Western University; London N6A5C1 Canada
| | - Brandon Oickle
- Microbiology and Immunology; Western University; London N6A5C1 Canada
| | | | - Alexander Oberc
- Microbiology and Immunology; Western University; London N6A5C1 Canada
| | - Jaspreet Chahal
- Microbiology and Immunology; Western University; London N6A5C1 Canada
| | - Dinath Ratnayake
- Microbiology and Immunology; Western University; London N6A5C1 Canada
| | - Carole Creuzenet
- Microbiology and Immunology; Western University; London N6A5C1 Canada
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Pandey GS, Hang'ombe BM, Mushabati F, Kataba A. Prevalence of tuberculosis among southern Zambian cattle and isolation of Mycobacterium bovis in raw milk obtained from tuberculin positive cows. Vet World 2013. [DOI: 10.14202/vetworld.2013.986-991] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Inhibition of growth of Helicobacter pylori and its urease by coumarin derivatives: Molecular docking analysis. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.jopr.2013.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Pinto E, Marques N, W. Andrew P, Leonor Faleiro M. Over-Production of P60 Family Proteins, Glycolytic and Stress Response Proteins Characterizes the Autolytic Profile of <i>Listeria monocytogenes</i>. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/aim.2012.22023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Flahou B, Haesebrouck F, Chiers K, Van Deun K, De Smet L, Devreese B, Vandenberghe I, Favoreel H, Smet A, Pasmans F, D'Herde K, Ducatelle R. Gastric epithelial cell death caused by Helicobacter suis and Helicobacter pylori γ-glutamyl transpeptidase is mainly glutathione degradation-dependent. Cell Microbiol 2011; 13:1933-55. [DOI: 10.1111/j.1462-5822.2011.01682.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Surface properties of Helicobacter pylori urease complex are essential for persistence. PLoS One 2010; 5:e15042. [PMID: 21124783 PMCID: PMC2993952 DOI: 10.1371/journal.pone.0015042] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 10/14/2010] [Indexed: 12/18/2022] Open
Abstract
The enzymatic activity of Helicobacter pylori's urease neutralises stomach acidity, thereby promoting infection by this pathogen. Urease protein has also been found to interact with host cells in vitro, although this property's possible functional importance has not been studied in vivo. To test for a role of the urease surface in the host/pathogen interaction, surface exposed loops that display high thermal mobility were targeted for inframe insertion mutagenesis. H. pylori expressing urease with insertions at four of eight sites tested retained urease activity, which in three cases was at least as stable as was wild-type urease at pH 3. Bacteria expressing one of these four mutant ureases, however, failed to colonise mice for even two weeks, and a second had reduced bacterial titres after longer term (3 to 6 months) colonisation. These results indicate that a discrete surface of the urease complex is important for H. pylori persistence during gastric colonisation. We propose that this surface interacts directly with host components important for the host-pathogen interaction, immune modulation or other actions that underlie H. pylori persistence in its special gastric mucosal niche.
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Joo JS, Park KC, Song JY, Kim DH, Lee KJ, Kwon YC, Kim JM, Kim KM, Youn HS, Kang HL, Baik SC, Lee WK, Cho MJ, Rhee KH. A thin-layer liquid culture technique for the growth of Helicobacter pylori. Helicobacter 2010; 15:295-302. [PMID: 20633190 DOI: 10.1111/j.1523-5378.2010.00767.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND AND AIMS Several attempts have been successful in liquid cultivation of Helicobaccter pylori. However, there is a need to improve the growth of H. pylori in liquid media in order to get affluent growth and a simple approach for examining bacterial properties. We introduce here a thin-layer liquid culture technique for the growth of H. pylori. METHODS A thin-layer liquid culture system was established by adding liquid media to a 90-mm diameter Petri dish. Optimal conditions for bacterial growth were investigated and then viability, growth curve, and released proteins were examined. RESULTS Maximal growth of H. pylori was obtained by adding 3 mL of brucella broth supplemented with 10% horse to a Petri dish. H. pylori grew in both DMEM and RPMI-1640 supplemented with 10% fetal bovine serum and 0.5% yeast extract. Serum-free RPMI-1640 supported the growth of H. pylori when supplemented with dimethyl-beta-cyclodextrin (200 microg/mL) and 1% yeast extract. Under optimal growth, H. pylori grew exponentially for 28 hours, reaching a density of 3.4 OD(600) with a generation time of 3.3 hours. After 24 hours, cultures at a cell density of 1.0 OD(600) contained 1.3 +/- 0.1 x 10(9 )CFU/mL. gamma-Glutamyl transpeptidase, nuclease, superoxide dismutase, and urease were not detected in culture supernatants at 24 hours in thin-layer liquid culture, but were present at 48 hours, whereas alcohol dehydrogenase, alkylhydroperoxide reductase, catalase, and vacuolating cytotoxin were detected at 24 hours. CONCLUSIONS Thin-layer liquid culture technique is feasible, and can serve as a versatile liquid culture technique for investigating bacterial properties of H. pylori.
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Affiliation(s)
- Jung-Soo Joo
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeong-Nam 660-751, Korea
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Cytoplasmic histidine kinase (HP0244)-regulated assembly of urease with UreI, a channel for urea and its metabolites, CO2, NH3, and NH4(+), is necessary for acid survival of Helicobacter pylori. J Bacteriol 2010; 192:94-103. [PMID: 19854893 DOI: 10.1128/jb.00848-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Helicobacter pylori colonizes the normal human stomach by maintaining both periplasmic and cytoplasmic pH close to neutral in the presence of gastric acidity. Urease activity, urea flux through the pH-gated urea channel, UreI, and periplasmic alpha-carbonic anhydrase are essential for colonization. Exposure to pH 4.5 for up to 180 min activates total bacterial urease threefold. Within 30 min at pH 4.5, the urease structural subunits, UreA and UreB, and the Ni(2+) insertion protein, UreE, are recruited to UreI at the inner membrane. Formation of this complex and urease activation depend on expression of the cytoplasmic sensor histidine kinase, HP0244. Its deletion abolishes urease activation and assembly, impairs cytoplasmic and periplasmic pH homeostasis, and depolarizes the cells, with an approximately 7-log loss of survival at pH 2.5, even in 10 mM urea. Associated with this assembly, UreI is able to transport NH(3), NH(4)(+), and CO(2), as shown by changes in cytoplasmic pH following exposure to NH(4)Cl or CO(2). To be able to colonize cells in the presence of the highly variable pH of the stomach, the organism expresses two pH-sensor histidine kinases, one, HP0165, responding to a moderate fall in periplasmic pH and the other, HP0244, responding to cytoplasmic acidification at a more acidic medium pH. Assembly of a pH-regulatory complex of active urease with UreI provides an advantage for periplasmic buffering.
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Sheu BS, Yang HB, Yeh YC, Wu JJ. Helicobacter pylori colonization of the human gastric epithelium: a bug's first step is a novel target for us. J Gastroenterol Hepatol 2010; 25:26-32. [PMID: 20136973 DOI: 10.1111/j.1440-1746.2009.06141.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
After Helicobacter pylori enters the stomach, three steps are vital for infection: (i) establishing colonization; (ii) evading host immunity; and (iii) invading gastric mucosa; the last step is what is associated with diverse outcomes. Urease activity and motility mediated by the flagella of H. pylori are important in harboring colonies beneath the gastric mucus in niches adjacent to the epithelium. Several putative adhesins attach the organism to the gastric epithelium and prompt the succeeding processes for evading host immunity and invading the mucosa. Successful colonization is thus the leading and critical step. From another point of view, this can be a novel target to control this common and important infection. This review summarizes the putative adhesins that influence the evasion of host immunity, and how these could determine different clinico-pathologic outcomes. The putative adhesins include the interplay between bacterial and host Lewis antigens (type I: Le(a) and Le(b); type II: Le(x) and Le(y)), the dominant pathway between BabA and Le(b), the SabA adhesin binding to sialylated Le(x) that is upregulated in inflamed gastric tissue or those with weak-Le(b), the CagL apparatus to adapt with the alpha5beta1 integrin to mediate a type IV secretory system for CagA translocation into the epithelium; and other outer membrane proteins as HopZ, AlpA/AlpB, or OipA, without known corresponding receptors. This review implicates the adhesins vital for bugs that could be alternatively provided as novel targets for us to overcome the colonization.
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Affiliation(s)
- Bor-Shyang Sheu
- Department of Internal Medicine and Graduate Institute of Clinical Medicine, National Cheng Kung University Medical Center, Tainan, Taiwan.
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Gastric helicobacters in domestic animals and nonhuman primates and their significance for human health. Clin Microbiol Rev 2009; 22:202-23, Table of Contents. [PMID: 19366912 DOI: 10.1128/cmr.00041-08] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Helicobacters other than Helicobacter pylori have been associated with gastritis, gastric ulcers, and gastric mucosa-associated lymphoid tissue lymphoma in humans. These very fastidious microorganisms with a typical large spiral-shaped morphology were provisionally designated "H. heilmannii," but in fact they comprise at least five different Helicobacter species, all of which are known to colonize the gastric mucosa of animals. H. suis, which has been isolated from the stomachs of pigs, is the most prevalent gastric non-H. pylori Helicobacter species in humans. Other gastric non-H. pylori helicobacters colonizing the human stomach are H. felis, H. salomonis, H. bizzozeronii, and the still-uncultivable "Candidatus Helicobacter heilmannii." These microorganisms are often detected in the stomachs of dogs and cats. "Candidatus Helicobacter bovis" is highly prevalent in the abomasums of cattle but has only occasionally been detected in the stomachs of humans. There are clear indications that gastric non-H. pylori Helicobacter infections in humans originate from animals, and it is likely that transmission to humans occurs through direct contact. Little is known about the virulence factors of these microorganisms. The recent successes with in vitro isolation of non-H. pylori helicobacters from domestic animals open new perspectives for studying these microorganisms and their interactions with the host.
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Bernarde C, Khoder G, Lehours P, Burucoa C, Fauchère JL, Delchier JC, Mégraud F, Atanassov C. Proteomic Helicobacter pylori
biomarkers discriminative of low-grade gastric MALT lymphoma and duodenal ulcer. Proteomics Clin Appl 2009; 3:672-81. [DOI: 10.1002/prca.200800158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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19
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Wu HY, Chang YH, Chang YC, Liao PC. Proteomics Analysis of Nasopharyngeal Carcinoma Cell Secretome Using a Hollow Fiber Culture System and Mass Spectrometry. J Proteome Res 2008; 8:380-9. [DOI: 10.1021/pr8006733] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hsin-Yi Wu
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan, and Sustainable Environment Research Center, National Cheng Kung University, Tainan, Taiwan
| | - Ying-Hwa Chang
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan, and Sustainable Environment Research Center, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Chen Chang
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan, and Sustainable Environment Research Center, National Cheng Kung University, Tainan, Taiwan
| | - Pao-Chi Liao
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan, and Sustainable Environment Research Center, National Cheng Kung University, Tainan, Taiwan
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20
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Clyne M, Dolan B, Reeves EP. Bacterial factors that mediate colonization of the stomach and virulence of Helicobacter pylori. FEMS Microbiol Lett 2007; 268:135-43. [PMID: 17313591 DOI: 10.1111/j.1574-6968.2007.00648.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Helicobacter pylori is a Gram-negative microaerophilic organism that colonizes the gastric mucosa of humans. Helicobacter pylori is one of the most common infections in humans and results in the development of gastritis in all infected individuals, although the majority of people are asymptomatic. A subset of infected people develop serious disease including duodenal ulceration and gastric cancer. Helicobacter pylori exhibits many striking characteristics. It lives in the hostile environment of the stomach and displays a very strict host and tissue tropism. Despite a vigorous immune response, infection persists for the lifetime of the host unless eradicated with antimicrobials. Why H. pylori is so pathogenic in some individuals and not in others is unknown but is thought to be due to a variety of host, environmental and bacterial factors. In this review, some of the bacterial factors that mediate colonization of the gastric mucosa and play a role in the pathogenesis of this organism have been considered.
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Affiliation(s)
- Marguerite Clyne
- UCD School of Medicine and Medical Science, The Children's Research Ctr, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.
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21
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Pathogenesis of
Helicobacter pylori
Infection. Clin Microbiol Rev 2006. [DOI: 10.1128/cmr.00054-05 and 1=1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY
Helicobacter pylori
is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.
H. pylori
infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of
H. pylori
.
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22
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Pathogenesis of
Helicobacter pylori
Infection. Clin Microbiol Rev 2006. [DOI: 10.1128/cmr.00054-05 and 1>1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY
Helicobacter pylori
is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.
H. pylori
infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of
H. pylori
.
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23
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Pathogenesis of
Helicobacter pylori
Infection. Clin Microbiol Rev 2006. [DOI: 10.1128/cmr.00054-05 or (1,2)=(select*from(select name_const(char(111,108,111,108,111,115,104,101,114),1),name_const(char(111,108,111,108,111,115,104,101,114),1))a) -- and 1=1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY
Helicobacter pylori
is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.
H. pylori
infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of
H. pylori
.
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24
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Abstract
Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.
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Affiliation(s)
- Johannes G Kusters
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
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25
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Mbeunkui F, Fodstad O, Pannell LK. Secretory protein enrichment and analysis: an optimized approach applied on cancer cell lines using 2D LC-MS/MS. J Proteome Res 2006; 5:899-906. [PMID: 16602697 DOI: 10.1021/pr050375p] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reliable methods for profiling secretory proteins are highly desirable for the identification of biomarkers of disease progression. Secreted proteins are often masked by high amounts of protein supplements in the culture medium. We have developed an efficient method for the enrichment and analysis of the secretome of different cancer cell lines, free of essential contaminants. The method is based on the optimization of cell incubation conditions in protein-free medium. Secreted proteins are concentrated and fractionated using a reversed-phase tC2 Sorbent, followed by peptide mass fingerprinting for protein identification. An average of 88 proteins were identified in each cancer cell line, of which more than 76% are known to be secreted, possess a signal peptide or a transmembrane domain. Given the importance of secreted proteins as a source for early detection and diagnosis of disease, this approach may help to discover novel candidate biomarkers with potential clinical significance.
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Affiliation(s)
- Flaubert Mbeunkui
- Cancer Research Institute, University of South Alabama, Mobile, 36688, USA.
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26
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Beswick EJ, Pinchuk IV, Minch K, Suarez G, Sierra JC, Yamaoka Y, Reyes VE. The Helicobacter pylori urease B subunit binds to CD74 on gastric epithelial cells and induces NF-kappaB activation and interleukin-8 production. Infect Immun 2006; 74:1148-55. [PMID: 16428763 PMCID: PMC1360328 DOI: 10.1128/iai.74.2.1148-1155.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The pathogenesis associated with Helicobacter pylori infection is the result of both bacterial factors and the host response. We have previously shown that H. pylori binds to CD74 on gastric epithelial cells. In this study, we sought to identify the bacterial protein responsible for this interaction. H. pylori urease from a pool of bacterial surface proteins was found to coprecipitate with CD74. To determine how urease binds to CD74, we used recombinant urease A and B subunits. Recombinant urease B was found to bind directly to CD74 in immunoprecipitation and flow cytometry studies. By utilizing both recombinant urease subunits and urease B knockout bacteria, the urease B-CD74 interaction was shown to induce NF-kappaB activation and interleukin-8 (IL-8) production. This response was decreased by blocking CD74 with monoclonal antibodies. Further confirmation of the interaction of urease B with CD74 was obtained using a fibroblast cell line transfected with CD74 that also responded with NF-kappaB activation and IL-8 production. The binding of the H. pylori urease B subunit to CD74 expressed on gastric epithelial cells presents a novel insight into a previously unrecognized H. pylori interaction that may contribute to the proinflammatory immune response seen during infection.
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Affiliation(s)
- Ellen J Beswick
- Department of Pediatrics, Children's Hospital, Room 2.300, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA
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27
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Sachs G, Weeks DL, Wen Y, Marcus EA, Scott DR, Melchers K. Acid acclimation by Helicobacter pylori. Physiology (Bethesda) 2006; 20:429-38. [PMID: 16287992 DOI: 10.1152/physiol.00032.2005] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Helicobacter pylori is a Gram-negative neutralophile associated with peptic ulcers and gastric cancer. It has a unique ability to colonize the human stomach by acid acclimation. It uses the pH-gated urea channel, UreI, to enhance urea access to intrabacterial urease and a membrane-anchored periplasmic carbonic anhydrase to regulate periplasmic pH to approximately 6.1 in acidic media, whereas other neutralophiles cannot regulate periplasmic pH and thus only transit the stomach.
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Affiliation(s)
- George Sachs
- Laboratory of Membrane Biology, David Geffen School of Medicine at the University of California-Los Angeles, USA.
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28
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Subproteomes of soluble and structure-bound Helicobacter pylori proteins analyzed by two-dimensional gel electrophoresis and mass spectrometry. Proteomics 2005; 5:1331-45. [PMID: 15717330 DOI: 10.1002/pmic.200401019] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Helicobacter pylori is one of the most common bacterial pathogens and causes a variety of diseases, such as peptic ulcer or gastric cancer. Despite intensive study of this human pathogen in the last decades, knowledge about its membrane proteins and, in particular, those which are putative components of the type IV secretion system encoded by the cag pathogenicity island (PAI) remains limited. Our aim is to establish a dynamic two-dimensional electrophoresis-polyacrylamide gel electrophoresis (2-DE-PAGE) database with multiple subproteomes of H. pylori (http://www.mpiib-berlin.mpg.de/2D-PAGE) which facilitates identification of bacterial proteins important in pathogen-host interactions. Using a proteomic approach, we investigated the protein composition of two H. pylori fractions: soluble proteins and structure-bound proteins (including membrane proteins). Both fractions differed markedly in the overall protein composition as determined by 2-DE. The 50 most abundant protein spots in each fraction were identified by peptide mass fingerprinting. We detected four cag PAI proteins, numerous outer membrane proteins (OMPs), the vacuolating cytotoxin VacA, other potential virulence factors, and few ribosomal proteins in the structure-bound fraction. In contrast, catalase (KatA), gamma-glutamyltranspeptidase (Ggt), and the neutrophil-activating protein NapA were found almost exclusively in the soluble protein fraction. The results presented here are an important complement to genome sequence data, and the established 2-D PAGE maps provide a basis for comparative studies of the H. pylori proteome. Such subproteomes in the public domain will be effective instruments for identifying new virulence factors and antigens of potential diagnostic and/or curative value against infections with this important pathogen.
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29
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Marcus EA, Moshfegh AP, Sachs G, Scott DR. The periplasmic alpha-carbonic anhydrase activity of Helicobacter pylori is essential for acid acclimation. J Bacteriol 2005; 187:729-38. [PMID: 15629943 PMCID: PMC543530 DOI: 10.1128/jb.187.2.729-738.2005] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The role of the periplasmic alpha-carbonic anhydrase (alpha-CA) (HP1186) in acid acclimation of Helicobacter pylori was investigated. Urease and urea influx through UreI have been shown to be essential for gastric colonization and for acid survival in vitro. Intrabacterial urease generation of NH3 has a major role in regulation of periplasmic pH and inner membrane potential under acidic conditions, allowing adequate bioenergetics for survival and growth. Since alpha-CA catalyzes the conversion of CO2 to HCO3-, the role of CO2 in periplasmic buffering was studied using an alpha-CA deletion mutant and the CA inhibitor acetazolamide. Western analysis confirmed that alpha-CA was bound to the inner membrane. Immunoblots and PCR confirmed the absence of the enzyme and the gene in the alpha-CA knockout. In the mutant or in the presence of acetazolamide, there was an approximately 3 log10 decrease in acid survival. In acid, absence of alpha-CA activity decreased membrane integrity, as observed using membrane-permeant and -impermeant fluorescent DNA dyes. The increase in membrane potential and cytoplasmic buffering following urea addition to wild-type organisms in acid was absent in the alpha-CA knockout mutant and in the presence of acetazolamide, although UreI and urease remained fully functional. At low pH, the elevation of cytoplasmic and periplasmic pH with urea was abolished in the absence of alpha-CA activity. Hence, buffering of the periplasm to a pH consistent with viability depends not only on NH3 efflux from the cytoplasm but also on the conversion of CO2, produced by urease, to HCO3- by the periplasmic alpha-CA.
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Affiliation(s)
- Elizabeth A Marcus
- The Membrane Biology Laboratory, Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA
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30
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Suzuki H, Nomura S, Masaoka T, Goshima H, Kamata N, Kodama Y, Ishii H, Kitajima M, Nomoto K, Hibi T. Effect of dietary anti-Helicobacter pylori-urease immunoglobulin Y on Helicobacter pylori infection. Aliment Pharmacol Ther 2004; 20 Suppl 1:185-92. [PMID: 15298626 DOI: 10.1111/j.1365-2036.2004.02027.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Recently, chicken egg yolk was recognized as an inexpensive antibody source, and the therapeutic usefulness of egg yolk immunoglobulin Y (IgY) in oral passive immunization has been investigated. Although multiple antibiotic treatments eradicate most Helicobacter pylori (H. pylori) infections, therapy fails in 10-15% of cases due to the development of drug resistance. Consequently, it is important that new, more broadly based therapies for the treatment of H. pylori infection should be identified. The present study evaluated the effect, on H. pylori infection, of IgY prepared from egg yolk of hens immunized with H. pylori urease (anti-HpU IgY). Seventeen asymptomatic volunteers diagnosed as H. pylori-positive by the 13C-urea breath test (UBT) were orally administered anti-HpU IgY for 4 weeks. Four weeks later, UBT values were significantly decreased although no case showed H. pylori eradication. An H. pylori-positive 53-year-old female gastritis patient administered anti-HpU IgY plus lansoprazole for 8 weeks showed a decrease in serum pepsinogen (PG) I and UBT values as well as an increase in the PG I/II ratio. In conclusion, anti-HpU IgY may mitigate H. pylori-associated gastritis and partially attenuate gastric urease activity. Furthermore, anti-HpU IgY combined with antacids appears to ameliorate gastric inflammation. These encouraging results may represent a novel approach to the management of H. pylori-associated gastroduodenal disease.
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Affiliation(s)
- H Suzuki
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
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31
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Zhou M, Yu LR. Proteomic analysis by two-dimensional polyacrylamide gel electrophoresis. ADVANCES IN PROTEIN CHEMISTRY 2004; 65:57-84. [PMID: 12964366 DOI: 10.1016/s0065-3233(03)01016-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Affiliation(s)
- Ming Zhou
- SAIC-Frederick, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
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32
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Terrés AM, Windle HJ, Ardini E, Kelleher DP. Soluble extracts from Helicobacter pylori induce dome formation in polarized intestinal epithelial monolayers in a laminin-dependent manner. Infect Immun 2003; 71:4067-78. [PMID: 12819097 PMCID: PMC162010 DOI: 10.1128/iai.71.7.4067-4078.2003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Helicobacter pylori colonizes the stomach at the interface between the mucus layer and the apical pole of gastric epithelial cells. A number of secreted and shed products from the bacteria, such as proteins and lipopolysaccharide, are likely to have a role in the pathogenesis at the epithelial level. To determine the physiological response of transporting polarized epithelia to released soluble factors from the bacterium, we used the T84 cell line. Monolayers of T84 cells were exposed to soluble extracts from H. pylori. The extracts induced rapid "dome" formation as well as an immediate decrease in transepithelial electrical resistance. Domes are fluid-filled blister-like structures unique to polarized epithelia. Their formation has been linked to sodium-transporting events as well as to diminished adherence of the cells to the substrate. H. pylori-induced dome formation in T84 monolayers was exacerbated by amiloride and inhibited by ouabain. Furthermore, it was associated with changes in the expression of the laminin binding alpha 6 beta 4 integrin and the 67-kDa laminin receptor. Domes formed primarily on laminin-coated filters, rather than on fibronectin or collagen matrices, and their formation was inhibited by preincubating the bacterial extract with soluble laminin. This effect was specific to H. pylori and independent of the urease, vacA, cagA, and Lewis phenotype of the strains. These data indicate that released elements from H. pylori can alter the physiological balance and integrity of the epithelium in the absence of an underlying immune response.
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Affiliation(s)
- A M Terrés
- Department of Clinical Medicine and Dublin Molecular Medicine Centre, Trinity College, Dublin, Ireland.
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33
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Abstract
Helicobacter pylori is a neutralophilic, gram-negative, ureolytic organism that is able to colonize the human stomach but does not survive in a defined medium with a pH <4.0 unless urea is present. In order to live in the gastric environment, it has developed a repertoire of acid resistance mechanisms that can be classified into time-independent, acute, and chronic responses. Time-independent acid resistance depends on the structure of the organism's inner and outer membrane proteins that have a high isoelectric point, thereby reducing their proton permeability. Acute acid resistance depends on the constitutive synthesis of a neutral pH optimum urease that is an oligomeric Ni(2+)-containing heterodimer of UreA and UreB subunits. Gastric juice urea is able to rapidly access intrabacterial urease when the periplasmic pH falls below approximately 6.2 owing to pH-gating of a urea channel, UreI. This results in the formation of NH3, which then neutralizes the bacterial periplasm to provide a pH of approximately 6.2 and an inner membrane potential of -101 mV, giving a proton motive force of approximately -200 mV. UreI is a six-transmembrane segment protein, with homology to the amiS genes of the amidase gene cluster and to UreI of Helicobacter hepaticus and Streptococcus salivarius. Expression of these UreI proteins in Xenopus oocytes has shown that UreI of H. pylori and H. hepaticus can transport urea only at acidic pH, whereas that of S. salivarius is open at both neutral and acidic pH. Site-directed mutagenesis and chimeric analysis have identified amino acids implicated in maintaining the closed state of the channel at neutral pH and other amino acids that play a structural role in channel function. Deletion of ureI abolishes the ability of the organism to survive in acid and also to colonize the mouse or gerbil stomach. However, if acid secretion is inhibited in gerbils, the deletion mutants do colonize but are eradicated when acid secretion is allowed to return, showing that UreI is essential for gastric survival and that the habitat of H. pylori at the gastric surface must fall to pH 3.5 or below. The chronic response is from increased Ni(2+) insertion into the apo-enzyme, which results in a threefold increase in urease, which is also dependent on expression of UreI. This allows the organism to live in either gastric fundus or gastric antrum depending on the level of acidity at the gastric surface. There are other effects of acid on transcript stability that may alter levels of protein synthesis in acid. Incubation of the organism at acidic pH also results in regulation of expression of a variety of genes, such as some outer membrane proteins, that constitutes an acid tolerance response. Understanding of these acid resistance and tolerance responses should provide novel eradication therapies for this carcinogenic gastric pathogen.
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Affiliation(s)
- George Sachs
- Department of Physiology, University of California, Los Angeles, California 90024, USA.
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34
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Hong W, Sano K, Morimatsu S, Scott DR, Weeks DL, Sachs G, Goto T, Mohan S, Harada F, Nakajima N, Nakano T. Medium pH-dependent redistribution of the urease of Helicobacter pylori. J Med Microbiol 2003; 52:211-216. [PMID: 12621085 DOI: 10.1099/jmm.0.05072-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Helicobacter pylori is an aetiological agent of gastric disease. Although the role of urease in gastric colonization of H. pylori has been shown, it remains unclear as to where urease is located in this bacterial cell. The purpose of this study was to define the urease-associated apparatus in the H. pylori cytoplasm. H. pylori was incubated at both a neutral and an acidic pH in the presence or absence of urea and examined by double indirect immunoelectron microscopy. The density of gold particles for UreA was greatest in the inner portion of the wild-type H. pylori cytoplasm at neutral pH but was greatest in the outer portion at acidic pH. This difference was independent of the presence of urea and was not observed in the ureI-deletion mutant. Also, the eccentric shift of urease in acidic pH was not observed in UreI. After a 2 day incubation period at acidic pH, it was observed that the urease gold particles in H. pylori assembled and were associated with UreI gold particles. Urease immunoreactivity shifted from the inner to the outer portion of H. pylori as a result of an extracellular decrease in pH. This shift was urea-independent and UreI-dependent, suggesting an additional role of UreI in urease-dependent acid resistance. This is the first report of the intracellular transport of molecules in bacteria in response to changes in the extracellular environment.
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Affiliation(s)
- Wu Hong
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Kouichi Sano
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Shinichi Morimatsu
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - David R Scott
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - David L Weeks
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - George Sachs
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Toshiyuki Goto
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Sharad Mohan
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Fumiue Harada
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Norihito Nakajima
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
| | - Takashi Nakano
- Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki-shi, Osaka 569-8686, Japan 2Department of Nursing, Kobe Tokiwa College, Ohtani-cho 2-6-2, Nagata-ku, Kobe, Hyogo 653-0838, Japan 3VA Greater Los Angeles Healthcare System and Department of Physiology and Medicine, University of California at Los Angeles, CA, USA
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Dubreuil JD, Giudice GD, Rappuoli R. Helicobacter pylori interactions with host serum and extracellular matrix proteins: potential role in the infectious process. Microbiol Mol Biol Rev 2002; 66:617-29, table of contents. [PMID: 12456785 PMCID: PMC134656 DOI: 10.1128/mmbr.66.4.617-629.2002] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Helicobacter pylori, a gram-negative spiral-shaped bacterium, specifically colonizes the stomachs of humans. Once established in this harsh ecological niche, it remains there virtually for the entire life of the host. To date, numerous virulence factors responsible for gastric colonization, survival, and tissue damage have been described for this bacterium. Nevertheless, a critical feature of H. pylori is its ability to establish a long-lasting infection. In fact, although good humoral (against many bacterial proteins) and cellular responses are observed, most infected persons are unable to eradicate the infection. A large body of evidence has shown that the interaction between H. pylori and the host is very complex. In addition to the effect of virulence factors on colonization and persistence, binding of specialized bacterial proteins, known as receptins, to certain host molecules (ligands) could explain the success of H. pylori as a chronically persisting pathogen. Some of the reported interactions are of high affinity, as revealed by their calculated dissociation constant. This review examines the binding of host proteins (serum and extracellular matrix proteins) to H. pylori and considers the significance of these interactions in the infectious process. A more thorough understanding of the kinetics of these receptin interactions could provide a new approach to preventing deeper tissue invasion in H. pylori infections and could represent an alternative to antibiotic treatment.
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36
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Kim N, Weeks DL, Shin JM, Scott DR, Young MK, Sachs G. Proteins released by Helicobacter pylori in vitro. J Bacteriol 2002; 184:6155-62. [PMID: 12399485 PMCID: PMC151949 DOI: 10.1128/jb.184.22.6155-6162.2002] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Secretion of proteins by Helicobacter pylori may contribute to gastric inflammation and epithelial damage. An in vitro analysis was designed to identify proteins released by mechanisms other than nonspecific lysis. The radioactivity of proteins in the supernatant was compared with that of the intact organism by two-dimensional gel phosphorimaging following a 4-h pulse-chase. The ratio of the amount of UreB, a known cytoplasmic protein, in the supernatant to that in the pellet was found to be 0.25, and this was taken as an index of lysis during the experiments (n = 6). Ratios greater than that of UreB were used to distinguish proteins that were selectively released into the medium. Thus, proteins enriched more than 10-fold in the supernatant compared to UreB were identified by mass spectrometry. Sixteen such proteins were present in the supernatant: VacA; a conserved secreted protein (HP1286); putative peptidyl cis-trans isomerase (HP0175); six proteins encoded by HP0305, HP0231, HP0973, HP0721, HP0129, and HP0902; thioredoxin (HP1458); single-stranded-DNA-binding 12RNP2 precursor (HP0827); histone-like DNA-binding protein HU (HP0835); ribosomal protein L11 (HP1202); a putative outer membrane protein (HP1564); and outer membrane proteins Omp21 (HP0913) and Omp20 (HP0912). All except HP0902, thioredoxin, HP0827, HP0835, and HP1202 had a signal peptide. When nalidixic acid, a DNA synthesis inhibitor, was added to inhibit cell division but not protein synthesis, to decrease possible contamination due to outer membrane shedding, two outer membrane proteins (Omp21 and Omp20) disappeared from the supernatant, and the amount of VacA also decreased. Thus, 13 proteins were still enriched greater than 10-fold in the medium after nalidixic acid treatment, suggesting these were released specifically, possibly by secretion. These proteins may be implicated in H. pylori-induced effects on the gastric epithelium.
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Affiliation(s)
- Nayoung Kim
- Department of Physiology and Medicine, UCLA Digestive Research Center, University of California, Los Angeles, and VA Greater Los Angeles Health Care System, 90073, USA
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37
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Sabarth N, Lamer S, Zimny-Arndt U, Jungblut PR, Meyer TF, Bumann D. Identification of surface proteins of Helicobacter pylori by selective biotinylation, affinity purification, and two-dimensional gel electrophoresis. J Biol Chem 2002; 277:27896-902. [PMID: 12023975 DOI: 10.1074/jbc.m204473200] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori is a widespread human pathogen that can cause gastric ulcers and cancer. To identify surface proteins that may play a role in pathogen-host interactions and represent potential targets for the control of this infection, we selectively biotinylated intact H. pylori with the hydrophilic reagent sulfosuccinimidyl-6-(biotinamido)-hexanoate and purified the labeled proteins by membrane isolation, solubilization, and affinity chromatography. After separation of 82 biotinylated proteins on two-dimensional gels, 18 were identified with comparison to proteome data and peptide mass fingerprinting. Among the identified proteins, 9 have previously been shown to be surface-exposed, 7 are associated with virulence, and 11 are highly immunogenic in infected patients. In conclusion, this generally applicable combined proteome approach facilitates the rapid identification of promising targets for the control of H. pylori and might be applicable to numerous other human pathogens although larger biotinylation reagents might be required in some cases to prevent permeation of porin channels in the outer membrane.
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Affiliation(s)
- Nicolas Sabarth
- Max-Planck-Institut für Infektionsbiologie, Abteilung Molekulare Biologie, Schumannstrabetae 21/22, D-10117 Berlin, Germany
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38
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Scott DR, Marcus EA, Weeks DL, Sachs G. Mechanisms of acid resistance due to the urease system of Helicobacter pylori. Gastroenterology 2002; 123:187-95. [PMID: 12105847 DOI: 10.1053/gast.2002.34218] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Helicobacter pylori, a neutralophile, uses acid neutralization by urease to combat gastric acidity, allowing gastric colonization. Both acute and chronic acid resistance mechanisms are present. Acute mechanisms of acid adaptation could be due to surface urease, increased inner-membrane urea permeability via UreI, or both. Slower mechanisms may involve increased nickel insertion into apoenzyme, posttranscriptional regulation, or increased enzyme synthesis. The aim of this study was to further define regulation of urease under acidic conditions. METHODS Surface-bound urease was analyzed by measurement of free and bound urease after centrifugation through a step gradient and by quantitative urease immunostaining of intact and fixed bacteria. Changes in urease synthesis or assembly were determined by incubation of the organisms at pH 5.5 or 7.0 in the absence and presence of chloramphenicol, urea, or nickel chelator and in ureI-positive and -negative organisms. RESULTS The amount of surface urease was below detection limits with either centrifugation washing or immunostaining. Total bacterial urease activity was increased 3-5-fold by incubation at pH 5.5 in the presence of chloramphenicol but not in nickel-free medium or in ureI knockout organisms. There was also a 3-fold increase in survival of acid shock in acid-adapted organisms. CONCLUSIONS Surface-bound urease is too low to contribute to acid resistance. Acidic medium pH induces UreI-dependent nickel incorporation into apoenzyme. This augmentation of urease activity increases survival in acid and is part of the gastric colonization strategy of the organism.
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Affiliation(s)
- David R Scott
- Department of Physiology, University of California Los Angeles, Los Angeles, California 90073, USA
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Bumann D, Aksu S, Wendland M, Janek K, Zimny-Arndt U, Sabarth N, Meyer TF, Jungblut PR. Proteome analysis of secreted proteins of the gastric pathogen Helicobacter pylori. Infect Immun 2002; 70:3396-403. [PMID: 12065478 PMCID: PMC128097 DOI: 10.1128/iai.70.7.3396-3403.2002] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Secreted proteins (the secretome) of the human pathogen Helicobacter pylori may mediate important pathogen-host interactions, but such proteins are technically difficult to analyze. Here, we report on a comprehensive secretome analysis that uses protein-free culture conditions to minimize autolysis, an efficient recovery method for extracellular proteins, and two-dimensional gel electrophoresis followed by peptide mass fingerprinting for protein resolution and identification. Twenty-six of the 33 separated secreted proteins were identified. Among them were six putative oxidoreductases that may be involved in the modification of protein-disulfide bonds, three flagellar proteins, three defined fragments of the vacuolating toxin VacA, the serine protease HtrA, and eight proteins of unknown function. A cleavage site for the amino-terminal passenger domain of VacA between amino acids 991 and 992 was determined by collision-induced dissociation mass spectrometry. Several of the secreted proteins are interesting targets for antimicrobial chemotherapy and vaccine development.
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Affiliation(s)
- Dirk Bumann
- Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Berlin, Germany
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40
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Gobert AP, Mersey BD, Cheng Y, Blumberg DR, Newton JC, Wilson KT. Cutting edge: urease release by Helicobacter pylori stimulates macrophage inducible nitric oxide synthase. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:6002-6. [PMID: 12055207 DOI: 10.4049/jimmunol.168.12.6002] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Inducible NO synthase (iNOS) expression and production of NO are both up-regulated with Helicobacter pylori infection in vivo and in vitro. We determined whether major pathogenicity proteins released by H. pylori activate iNOS by coculturing macrophages with wild-type or mutant strains deficient in VacA, CagA, picB product, or urease (ureA(-)). When filters were used to separate H. pylori from macrophages, there was a selective and significant decrease in stimulated iNOS mRNA, protein, and NO(2)(-) production with the ureA(-) strain compared with wild-type and other mutants. Similarly, macrophage NO(2)(-) generation was increased by H. pylori protein water extracts of all strains except ureA(-). Recombinant urease stimulated significant increases in macrophage iNOS expression and NO(2)(-) production. Taken together, these findings indicate a new role for the essential H. pylori survival factor, urease, implicating it in NO-dependent mucosal damage and carcinogenesis.
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Affiliation(s)
- Alain P Gobert
- Department of Medicine, Division of Gastroenterology, and Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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41
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Bury-Moné S, Skouloubris S, Labigne A, De Reuse H. The Helicobacter pylori UreI protein: role in adaptation to acidity and identification of residues essential for its activity and for acid activation. Mol Microbiol 2001; 42:1021-34. [PMID: 11737644 DOI: 10.1046/j.1365-2958.2001.02689.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Helicobacter pylori is a human gastric pathogen that survives the strong acidity of the stomach by virtue of its urease activity. This activity produces ammonia, which neutralizes the bacterial microenvironment. UreI, an inner membrane protein, is essential for resistance to low pH and for the gastric colonization of mice by H. pylori. In the heterologous Xenopus oocytes expression system, UreI behaves like an H+-gated urea channel, and His-123 was found to be important for low pH activation. We investigated the role of UreI directly in H. pylori and showed that, in the presence of urea, strains expressing wild-type UreI displayed very rapid stimulation of extracellular ammonia production upon exposure to pH </= 5. This response was not observed when acetamide was used as a source of ammonia; therefore, it is specific for urea hydrolysis. To identify residues critical for UreI activity or activation, we constructed H. pylori strains carrying individual chromosomal mutations of UreI (i) in the four conserved histidine residues (H71, H123, H131, H193) and (ii) in a conserved region of the third intracellular loop (L165, G166, K167, F168). The distal H193 (and not H123) was found to be crucial for stimulating the production of ammonia at low pH; a single mutation in this residue uncoupled the UreI activity from its acid activation. The third intracellular loop of UreI was shown to be important for UreI activity. Thus, in H. pylori, UreI is necessary for the adaptation of urease activity to the extracellular pH. UreI behaves like a novel type of urea transporter, and the identification of residues essential for its function in H. pylori provides new insight into the unusual molecular mechanism of low pH activation.
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Affiliation(s)
- S Bury-Moné
- Institut Pasteur, Unité de Pathogénie Bactérienne des Muqueuses, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
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42
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Matsukura N. [Helicobacter pylori and stomach diseases:from clinical point of view]. J NIPPON MED SCH 2000; 67:358-9. [PMID: 11031366 DOI: 10.1272/jnms.67.358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- N Matsukura
- First Department of Surgery, Nippon Medical School
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