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Abstract
Acid-resistance in gastric pathogen Helicobacter pylori requires the coordination of four essential processes to regulate urease activity. Firstly, urease expression above a base level needs to be finely tuned at different ambient pH. Secondly, as nickel is needed to activate urease, nickel homeostasis needs to be maintained by proteins that import and export nickel ions, and sequester, store and release nickel when needed. Thirdly, urease accessary proteins that activate urease activity by nickel insertion need to be expressed. Finally, a reliable source of urea needs to be maintained by both intrinsic and extrinsic sources of urea. Two-component systems (arsRS and flgRS), as well as a nickel response regulator (NikR), sense the change in pH and act on a variety of genes to accomplish the function of acid resistance without causing cellular overalkalization and nickel toxicity. Nickel storage proteins also feature built-in switches to store nickel at neutral pH and release nickel at low pH. This review summarizes the current status of H. pylori research and highlights a number of hypotheses that need to be tested.
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Affiliation(s)
- Xuhua Xia
- Department of Biology, University of Ottawa, Ottawa, Canada; Ottawa Institute of Systems Biology, Ottawa, Canada.
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2
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Akashi T, Isomoto H, Matsushima K, Kamiya M, Kanda T, Nakano M, Onoyama T, Fujii M, Akada J, Akazawa Y, Ohnita K, Takeshima F, Nakao K, Urano Y. A novel method for rapid detection of a Helicobacter pylori infection using a γ-glutamyltranspeptidase-activatable fluorescent probe. Sci Rep 2019; 9:9467. [PMID: 31263136 PMCID: PMC6603024 DOI: 10.1038/s41598-019-45768-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 06/10/2019] [Indexed: 12/14/2022] Open
Abstract
A γ-glutamyl hydroxymethyl rhodamine green probe (gGlu-HMRG) reacts with γ-glutamyltranspeptidase (GGT) and immediately produces fluorescence, is clinically applied for real-time cancers' visualization. Since Helicobacter pylori produces GGT, this study aimed to investigate whether gGlu-HMRG can be used to detect H. pylori infections. A wild-type H. pylori strain and the ggt gene-disrupted mutant were cultured and treated with gGlu-HMRG. This fluorescent probe assay was used to quantify GGT activity of H. pylori ex vivo using gastric biopsy specimens. The H. pylori diagnostic capabilities of the assay were determined from altered fluorescence intensity (FI) values at 5 min (FIV-5) and 15 minutes (FIV-15). Distinct fluorescence was identified in wild H. pylori strain, using gGlu-HMRG, whereas no fluorescence was observed in ggt gene-disrupted mutant strain. On ex vivo imaging of gGlu-HMRG, fluorescence intensity increased markedly with time in H. pylori-positive specimens; however, the H. pylori-negative specimens displayed a slight increase in FI. FIV-5 and FIV-15 differed significantly between H. pylori-positive and -negative specimens. FIV-15 differed significantly between H. pylori-positive and -eradicated group. This assay sensitivity and specificity were 75.0% and 83.3% in the antrum and 82.6% and 89.5% in the stomach body. GGT-activatable fluorescence probe is applicable for rapid diagnosis of H. pylori.
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Affiliation(s)
- Taro Akashi
- Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Hajime Isomoto
- Divison of Medicine and Clinical Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan.
| | - Kayoko Matsushima
- Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Mako Kamiya
- Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tsutomu Kanda
- Divison of Medicine and Clinical Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Masayuki Nakano
- Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.,Department of International Health, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Takumi Onoyama
- Divison of Medicine and Clinical Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Masashi Fujii
- Divison of Medicine and Clinical Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago, 683-8504, Japan
| | - Junko Akada
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Yufu, Japan
| | - Yuko Akazawa
- Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Ken Ohnita
- Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Fuminao Takeshima
- Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Kazuhiko Nakao
- Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Yasuteru Urano
- Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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3
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Abstract
Codon usage depends on mutation bias, tRNA-mediated selection, and the need for high efficiency and accuracy in translation. One codon in a synonymous codon family is often strongly over-used, especially in highly expressed genes, which often leads to a high dN/dS ratio because dS is very small. Many different codon usage indices have been proposed to measure codon usage and codon adaptation. Sense codon could be misread by release factors and stop codons misread by tRNAs, which also contribute to codon usage in rare cases. This chapter outlines the conceptual framework on codon evolution, illustrates codon-specific and gene-specific codon usage indices, and presents their applications. A new index for codon adaptation that accounts for background mutation bias (Index of Translation Elongation) is presented and contrasted with codon adaptation index (CAI) which does not consider background mutation bias. They are used to re-analyze data from a recent paper claiming that translation elongation efficiency matters little in protein production. The reanalysis disproves the claim.
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Abstract
This review summarizes the most recent data on the biological characteristics of Helicobacter pylori (morphological, cultural, biochemical). H. pylori pathogenicity factors promoting colonization, adhesion, biofilm formation, aggression, and cytotoxicity, their contribution to the pathogenesis of diseases as well as the possible relationships with various clinical outcomes are described in detail. The genetic heterogeneity of H. pylori strains which can determine different clinical manifestations and have significance for conducting epidemiological studies is also considered.
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Affiliation(s)
- G.Sh. Isaeva
- Kazan Research Institute of Epidemiology and Microbiology; Kazan State Medical University (Kazan, Russia)
| | - R.I. Valieva
- Kazan Research Institute of Epidemiology and Microbiology; KazanState Medical University (Kazan, Russia)
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5
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Abstract
This review aimed to investigate the role of Helicobacter pylori flagella on the pathogenicity of this bacterium in humans. Helicobacter pylori is a flagellated pathogen that colonizes the human gastroduodenal mucosa and produces inflammation, and is responsible for gastrointestinal disease. Its pathogenesis is attributed to colonization and virulence factors. The primary function of H. pylori flagella is to provide motility. We believe that H. pylori flagella play an important role in the colonization of the gastrointestinal mucosa. Therefore, we reviewed previous studies on flagellar morphology and motility in order to explore the relationship between H. pylori flagella and pathogenicity. Further investigation is required to confirm the association between flagella and pathogenicity in H. pylori.
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Affiliation(s)
- Haiying Gu
- Medical School, Ningbo University, Ningbo, 315211, China.
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Valenzuela M, Cáceres A, Almarza O, Bravo D, Soto S, Cerda O, Toledo H. Characterization of the arginine decarboxylase gene (ORF HP0422, speA) involved in acid tolerance in Helicobacter pylori. Helicobacter 2014; 19:182-93. [PMID: 24628778 DOI: 10.1111/hel.12115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Helicobacter pylori is a motile microaerophilic bacterium that colonizes the human stomach. H. pylori infection triggers gastric diseases, such as gastritis, peptic ulcer and gastric cancer. Stomach represents a barrier for microorganism colonization, particularly because of its high hydrochloric acid concentration. The main mechanism developed by H. pylori to maintain intracellular pH homeostasis in this environment is the urease activity. However, urease negative strains can be also isolated from clinical samples, suggesting that H. pylori presents other components involved in acid resistance. OBJECTIVE Here, we present some evidence that the arginine decarboxylase gene (speA) in H. pylori could be involved in an acid adaptation mechanism similar to the one in Enterobacteriaceae, which is dependent on the presence of arginine. METHODS Indeed, speA mRNA and protein expression are acutely induced by acid stress. RESULTS Moreover, we showed that H. pylori uses arginine in an acid response mechanism required for its growth in acid conditions. CONCLUSION Altogether, these results provide novel information regarding the H. pylori physiology and acid response mechanism.
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Affiliation(s)
- Manuel Valenzuela
- Faculty of Medicine, Department of Molecular and Cellular Biology, Laboratory of Molecular Microbiology, ICBM, University of Chile, Santiago, Chile; Toxicology and Cancer Biology Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, Bruxelles, Belgium
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7
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Pastene E, Parada V, Avello M, Ruiz A, García A. Catechin-based Procyanidins from Peumus boldus
Mol. Aqueous Extract Inhibit Helicobacter pylori
Urease and Adherence to Adenocarcinoma Gastric Cells. Phytother Res 2014; 28:1637-45. [DOI: 10.1002/ptr.5176] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 04/28/2014] [Accepted: 04/29/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Edgar Pastene
- Laboratory of Pharmacognosy, Department of Pharmacy, Faculty of Pharmacy; University of Concepción; Concepción Chile
| | - Víctor Parada
- Laboratory of Pharmacognosy, Department of Pharmacy, Faculty of Pharmacy; University of Concepción; Concepción Chile
| | - Marcia Avello
- Laboratory of Pharmacognosy, Department of Pharmacy, Faculty of Pharmacy; University of Concepción; Concepción Chile
| | - Antonieta Ruiz
- Laboratory of Chromatography, Department of Instrumental Analysis; University of Concepción; Concepción Chile
| | - Apolinaria García
- Laboratory of Bacterial Pathogenicity, Department of Microbiology, Faculty of Biological Sciences; University of Concepción; Concepción Chile
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Okamoto T, Hayashi Y, Mizuno H, Yanai H, Nishikawa J, Nakazawa T, Iizasa H, Jinushi M, Sakaida I, Yoshiyama H. Colonization of an acid resistant Kingella denitrificans in the stomach may contribute to gastric dysbiosis by Helicobacter pylori. J Infect Chemother 2013; 20:169-74. [PMID: 24462438 DOI: 10.1016/j.jiac.2013.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/04/2013] [Accepted: 09/16/2013] [Indexed: 12/15/2022]
Abstract
In the stomach of a gastric ulcer patient who had been administered an anti-acid, a gram-negative and urease-negative bacillus similar in size to Helicobacter pylori was infected together with H. pylori. According to biochemical test and 16S rRNA gene analysis, the urease-negative bacterium was identified as Kingella denitrificans, a human nasopharyngeal commensal. In contrast to the standard strain of K. denitrificans, the isolate showed catalase activity, did not produce acid from glucose, and exhibited acid tolerance. Acid tolerance of H. pylori was increased by cocultivation with the K. denitrificans isolate, but not with other isolates of K. denitrificans. Disruption of physiological and immunological niche by dysbiotic colonization of bacterium may provide pathological attributes to human stomach. Collectively, a careful administration of anti-acids to the elderly, especially those with atrophic gastritis, is necessary to avoid repression of the gastric barrier to bacteria.
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Affiliation(s)
- Takeshi Okamoto
- Yamaguchi University, Graduate School of Medicine, Minamikogushi 1-1-1, Ube, Yamaguchi 755-8505, Japan
| | - Yasuhiro Hayashi
- Institute for Genetic Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-0815, Japan
| | - Hidekazu Mizuno
- Clinical Laboratory, Yamaguchi University Hospital, Minamikogushi 1-1-1, Ube, Yamaguchi 755-8505, Japan
| | - Hideo Yanai
- Department of Clinical Research, National Hospital Organization Kanmon Medical Center, 1-1 Sotoura, Chofu, Shimonoseki, Yamaguchi 752-8510, Japan
| | - Jun Nishikawa
- Yamaguchi University, Graduate School of Medicine, Minamikogushi 1-1-1, Ube, Yamaguchi 755-8505, Japan
| | - Teruko Nakazawa
- Yamaguchi University, Graduate School of Medicine, Minamikogushi 1-1-1, Ube, Yamaguchi 755-8505, Japan
| | - Hisashi Iizasa
- Institute for Genetic Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-0815, Japan
| | - Masahisa Jinushi
- Institute for Genetic Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-0815, Japan
| | - Isao Sakaida
- Yamaguchi University, Graduate School of Medicine, Minamikogushi 1-1-1, Ube, Yamaguchi 755-8505, Japan
| | - Hironori Yoshiyama
- Institute for Genetic Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-0815, Japan.
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9
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Posselt G, Backert S, Wessler S. The functional interplay of Helicobacter pylori factors with gastric epithelial cells induces a multi-step process in pathogenesis. Cell Commun Signal 2013; 11:77. [PMID: 24099599 PMCID: PMC3851490 DOI: 10.1186/1478-811x-11-77] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 10/01/2013] [Indexed: 12/16/2022] Open
Abstract
Infections with the human pathogen Helicobacter pylori (H. pylori) can lead to severe gastric diseases ranging from chronic gastritis and ulceration to neoplastic changes in the stomach. Development and progress of H. pylori-associated disorders are determined by multifarious bacterial factors. Many of them interact directly with host cells or require specific receptors, while others enter the host cytoplasm to derail cellular functions. Several adhesins (e.g. BabA, SabA, AlpA/B, or OipA) establish close contact with the gastric epithelium as an important first step in persistent colonization. Soluble H. pylori factors (e.g. urease, VacA, or HtrA) have been suggested to alter cell survival and intercellular adhesions. Via a type IV secretion system (T4SS), H. pylori also translocates the effector cytotoxin-associated gene A (CagA) and peptidoglycan directly into the host cytoplasm, where cancer- and inflammation-associated signal transduction pathways can be deregulated. Through these manifold possibilities of interaction with host cells, H. pylori interferes with the complex signal transduction networks in its host and mediates a multi-step pathogenesis.
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Affiliation(s)
- Gernot Posselt
- Division of Molecular Biology, Department of Microbiology, Paris-Lodron University, Salzburg, Austria.
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10
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Alka K, Windle HJ, Cornally D, Ryan BJ, Henehan GTM. A short chain NAD(H)-dependent alcohol dehydrogenase (HpSCADH) from Helicobacter pylori: a role in growth under neutral and acidic conditions. Int J Biochem Cell Biol 2013; 45:1347-55. [PMID: 23583739 DOI: 10.1016/j.biocel.2013.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/27/2013] [Accepted: 04/03/2013] [Indexed: 11/18/2022]
Abstract
Toxic aldehydes produced by alcohol dehydrogenases have been implicated in the pathogenesis of Helicobacter pylori-related damage to the gastric mucosa. Despite this, the enzymes that might be responsible for producing such aldehydes have not been fully described. It was, therefore, of considerable interest to characterize the alcohol oxidizing enzymes in this pathogen. Previous work in this laboratory characterized two such H. pylori enzymes that had broad specificity for a range of aromatic alcohol substrates. However, an enzyme with specificity for aliphatic alcohols is likely to be required in order that H. pylori can metabolize the wide range of substrates encountered in the gastric mucosa. In this study we describe HpSCADH, an alcohol dehydrogenase from H. pylori 26695 with broad specificity for aliphatic alcohols. HpSCADH was classified in the cD1e subfamily of classical short chain alcohol dehydrogenases. The enzyme was a monomer of approximately 29kDa with a preference for NAD(+) as cofactor. Pyrazole was found to be a competitive inhibitor of HpSCADH. The physiological role of this enzyme was explored by construction of an HpSCADH isogenic mutant. At pH 7.0 the mutant showed reduced growth which became more pronounced when the pH was lowered to 5.0. When pyrazole was added to wild type H. pylori cells it caused growth profiles to be reduced to match those of the isogenic mutant suggesting that HpSCADH inhibition alone was responsible for growth impairment. Taken together, the data relating to the alcohol metabolizing enzymes of this pathogen indicate that they play an important role in H. pylori growth and adaptation to acidic environments. The therapeutic potential of targeting H. pylori alcohol dehydrogenases is discussed.
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Affiliation(s)
- Kumari Alka
- School of Food Science and Environmental Health, Dublin Institute of Technology, Marlborough Street, Dublin 1, Ireland
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Castillo-Juarez I, Rangel-Vega A, Romero I. Rapid paper disk test for identification of Helicobacter pylori in mixed cultures of gerbil gastric homogenates. J Microbiol Methods 2010; 83:20-5. [PMID: 20624429 DOI: 10.1016/j.mimet.2010.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Accepted: 07/06/2010] [Indexed: 01/27/2023]
Abstract
A method denominated rapid paper disk test (RPDT) was developed to identify H. pylori colonies in complex cultures obtained from gerbil gastric homogenates. Identification is based on a characteristic reaction pattern (RP) for H. pylori colonies given by the combination of the urease-oxidase activities on a paper disk. Compared to the RPs obtained from gerbil's intestinal tract isolated bacteria, H. pylori RP is completely distinguishable, even from those of bacteria that share one or both activities as are Aerococcus urinae, Bacillus sphaericus, Bacillus brevis, Corynebacterium pseudogenitalium, and Staphylococcus simulans, as well as from those produced by collection strains Proteus vulgaris and Pseudomonas aeruginosa. This method allows the practical quantification of H. pylori colonies in highly contaminated plates. RPDT has the following advantages over other methodologies that use indicators in the medium: it employs two of the three routinely used H. pylori biochemical identification tests, the reagents do not interfere with bacterial viability, there are no restrictions in relation to the medium used, and it is a simple, fast, and low-cost method.
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Affiliation(s)
- Israel Castillo-Juarez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, México, D.F., México
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12
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Haesebrouck F, Pasmans F, Flahou B, Chiers K, Baele M, Meyns T, Decostere A, Ducatelle R. Gastric helicobacters in domestic animals and nonhuman primates and their significance for human health. Clin Microbiol Rev. 2009;22:202-223, 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] [What about the content of this article? (0)] [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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Cornally D, Mee B, MacDonaill C, Tipton KF, Kelleher D, Windle HJ, Henehan GTM. Aldo-keto reductase from Helicobacter pylori--role in adaptation to growth at acid pH. FEBS J 2008; 275:3041-50. [PMID: 18445038 DOI: 10.1111/j.1742-4658.2008.06456.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyridine-linked oxidoreductase enzymes of Helicobacter pylori have been implicated in the pathogenesis of gastric disease. Previous studies in this laboratory examined a cinnamyl alcohol dehydrogenase that was capable of detoxifying a range of aromatic aldehydes. In the present work, we have extended these studies to identify and characterize an aldoketo reductase (AKR) enzyme present in H. pylori. The gene encoding this AKR was identified in the sequenced strain of H. pylori, 26695. The gene, referred to as HpAKR, was cloned and expressed in Escherichia coli as a His-tag fusion protein, and purified using nickel chelate chromatography. The gene product (HpAKR) has been assigned to the AKR13C1 family, although it differs in specificity from the two other known members of this family. The enzyme is a monomer with a molecular mass of approximately 39 kDa on SDS/PAGE. It reduces a range of aromatic aldehyde substrates with high catalytic efficiency, and exhibits dual cofactor specificity for both NADPH and NADH. HpAKR can function over a broad pH range (pH 4-9), and has a pH optimum of 5.5. It is inhibited by sodium valproate. Its substrate specificity complements that of the cinnamyl alcohol dehydrogenase activity in H. pylori, giving the organism the capacity to reduce a wide range of aldehydes. Generation of an HpAKR isogenic mutant of H. pylori demonstrated that HpAKR is required for growth under acidic conditions, suggesting an important role for this enzyme in adaptation to growth in the gastric mucosa. This AKR is a member of a hitherto little-studied class.
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Affiliation(s)
- Denise Cornally
- School of Food Science and Environmental Health, Dublin Institute of Technology, Ireland
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14
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Abstract
Helicobacter pylori, a Gram-negative flagellate bacterium that infects the stomach of more than half of the global population, is regarded as the leading cause of chronic gastritis, peptic ulcer disease, and even gastric adenocarcinoma in some individuals. Although the bacterium induces strong humoral and cellular immune responses, it can persist in the host for decades. It has several virulence factors, some of them having vaccine potential as judged by immunoproteomic analysis. A few vaccination studies involving a small number of infected or uninfected humans with various H. pylori formulations such as the recombinant urease, killed whole cells, and live Salmonella vectors presenting the subunit antigens have not provided satisfactory results. One trial that used the recombinant H. pylori urease coadministered with native Escherichia coli enterotoxin (LT) demonstrated a reduction of H. pylori load in infected participants. Although extensive studies in the mouse model have demonstrated the feasibility of both therapeutic and prophylactic immunizations, the mechanism of vaccine-induced protection is poorly understood as several factors such as immunoglobulin and various cytokines do not contribute to protection. Transcriptome analyses in mice have indicated the role of nonclassical immune factors in vaccine-induced protection. The role of regulatory T cells in the persistence of H. pylori infection has also been suggested. A recently developed experimental H. pylori infection model in humans may be used for testing several new adjuvants and vaccine delivery systems that have been currently obtained. The use of vaccines with appropriate immunogens, routes of immunization, and adjuvants along with a better understanding of the mechanism of immune protection may provide more favorable results.
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Affiliation(s)
- Shahjahan Kabir
- Academic Research and Information Management, Uppsala, Sweden.
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15
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Park JW, Song JY, Lee SG, Jun JS, Park JU, Chung MJ, Ju JS, Nizamutdinov D, Chang MW, Youn HS, Kang HL, Baik SC, Lee WK, Cho MJ, Rhee KH. Quantitative analysis of representative proteome components and clustering of Helicobacter pylori clinical strains. Helicobacter 2006; 11:533-43. [PMID: 17083375 DOI: 10.1111/j.1523-5378.2006.00456.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Several Helicobacter pylori proteins have been reported to be associated with severe symptoms of gastric disease. However, expression levels of most of these disease-associated proteins require further evaluation in order to clarify their relationships with gastric disease patterns. Representative proteome components of 71 clinical isolates of H. pylori were analyzed quantitatively to determine whether the protein expression levels were associated with gastric diseases and to cluster clinical isolates. METHODS After two-dimensional electrophoresis (2-DE) of H. pylori isolates, spot intensities were analyzed using pdquest 2-D Gel Analysis Software. The intensities of 10 representative protein spots, identified by peptide fingerprinting using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using quadrupole TOF MS, were subjected to the nonparametric Mann-Whitney test and hierarchical agglomerative cluster analysis. The relationship between clusters and gastric diseases was analyzed by the chi-squared test. RESULTS Although the spot intensities of the 10 representative proteins were highly variable within each gastric disease group, the expression levels of CagA, UreB, GroEL, EF-Tu, EF-P, TagD, and FldA showed some significant differences among the gastric disease patterns. On the basis of the 10 target protein intensities, hierarchical agglomerative cluster analysis generated a dendrogram with clusters indicative of chronic gastritis/gastric cancers and gastric/duodenal ulcers. CONCLUSION These results indicated that quantitative analysis of proteome components is a feasible method for examining disease-associated proteins and clustering clinical strains of H. pylori.
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Affiliation(s)
- Jeong-Won Park
- Department of Microbiology, Gyeongsang National University College of Medicine, Jinju, Gyeong-Nam, Korea
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16
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Abstract
PURPOSE OF REVIEW Virulence factors are related to the ability of a microbe to induce disease. True virulence factors must therefore have a disease association, an in-vivo correlate with disease such as increased mucosal inflammation, or both. RECENT FINDINGS The cytotoxin-associated gene pathogenicity island; the outer membrane inflammatory protein; the duodenal ulcer-promoting gene, and possibly the blood group antigen-binding adhesion, are the only factors that to date qualify as virulence factors. Numerous recent studies have investigated the interaction of vacuolating cytotoxin A or cytotoxin-associated gene A with cells and cell lines in vitro. It remains unclear, however, whether any of the findings, for example, in-vitro experiments showing that vacuolating cytotoxin A affect the regulation of T or B lymphocytes, have an in-vivo counterpart, or play any role in disease pathogenesis. SUMMARY The criteria for a virulence factor include evidence of an association with a disease or a disease surrogate such as the severity of mucosal inflammation, epidemiologic consistency, and biologic plausibility. Confirmation of the proposed mechanism requires elimination of the effect by gene deletion and restoration by complementation. Cytotoxin-associated gene A has been the subject of elegant biochemistry despite lack of evidence that it is involved in pathogenesis. The current focus of research on Helicobacter pylori relates to exploring the biology of Helicobacter pylori, often using systems that only vaguely relate to the in-vivo conditions or to disease pathogenesis.
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Affiliation(s)
- Hong Lu
- Department of Medicine, Michael E. DeBakey Veterans Affairs Medical Center, and Baylor College of Medicine, Houston, TX 77030, USA
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