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Zimmerman EH, Ramsey EL, Hunter KE, Villadelgado SM, Phillips CM, Shipman RT, Forsyth MH. The Helicobacter pylori methylome is acid-responsive due to regulation by the two-component system ArsRS and the type I DNA methyltransferase HsdM1 (HP0463). J Bacteriol 2024; 206:e0030923. [PMID: 38179929 PMCID: PMC10810217 DOI: 10.1128/jb.00309-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024] Open
Abstract
In addition to its role in genome protection, DNA methylation can regulate gene expression. In this study, we characterized the impact of acidity, phase variation, and the ArsRS TCS on the expression of the Type I m6A DNA methyltransferase HsdM1 (HP0463) of Helicobacter pylori 26695 and their subsequent effects on the methylome. Transcription of hsdM1 increases at least fourfold in the absence of the sensory histidine kinase ArsS, the major acid-sensing protein of H. pylori. hsdM1 exists in the phase-variable operon hsdR1-hsdM1. Phase-locking hsdR1 (HP0464), the restriction endonuclease gene, has significant impacts on the transcription of hsdM1. To determine the impacts of methyltransferase transcription patterns on the methylome, we conducted methylome sequencing on samples cultured at pH 7 or pH 5. We found differentially methylated motifs between these growth conditions and that deletions of arsS and/or hsdM1 interfere with the epigenetic acid response. Deletion of arsS leads to altered activity of HsdM1 and multiple other methyltransferases under both pH conditions indicating that the ArsRS TCS, in addition to direct effects on regulon transcription during acid acclimation, may also indirectly impact gene expression via regulation of the methylome. We determined the target motif of HsdM1 (HP0463) to be the complementary bipartite sequence pair 5'-TCAm6AVN6TGY-3' and 3'-AGTN6GAm6ACA-5'. This complex regulation of DNA methyltransferases, and thus differential methylation patterns, may have implications for the decades-long persistent infection by H. pylori. IMPORTANCE This study expands the possibilities for complex, epigenomic regulation in Helicobacter pylori. We demonstrate that the H. pylori methylome is plastic and acid sensitive via the two-component system ArsRS and the DNA methyltransferase HsdM1. The control of a methyltransferase by ArsRS may allow for a layered response to changing acidity. Likely, an early response whereby ArsR~P affects regulon expression, including the methyltransferase hsdM1. Then, a somewhat later effect as the altered methylome, due to altered HsdM1 expression, subsequently alters the expression of other genes involved in acclimation. The intermediate methylation of certain motifs supports the hypothesis that methyltransferases play a regulatory role. Untangling this additional web of regulation could play a key role in understanding H. pylori colonization and persistence.
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Affiliation(s)
| | - Erin L. Ramsey
- Department of Biology, William & Mary, Williamsburg, Virginia, USA
| | | | | | | | - Ryan T. Shipman
- Department of Biology, William & Mary, Williamsburg, Virginia, USA
| | - Mark H. Forsyth
- Department of Biology, William & Mary, Williamsburg, Virginia, USA
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2
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Biomarker Characterization and Prediction of Virulence and Antibiotic Resistance from Helicobacter pylori Next Generation Sequencing Data. Biomolecules 2022; 12:biom12050691. [PMID: 35625618 PMCID: PMC9138241 DOI: 10.3390/biom12050691] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/02/2022] [Accepted: 05/07/2022] [Indexed: 02/06/2023] Open
Abstract
The Gram-negative bacterium Helicobacter pylori colonizes c.a. 50% of human stomachs worldwide and is the major risk factor for gastric adenocarcinoma. Its high genetic variability makes it difficult to identify biomarkers of early stages of infection that can reliably predict its outcome. Moreover, the increasing antibiotic resistance found in H. pylori defies therapy, constituting a major human health problem. Here, we review H. pylori virulence factors and genes involved in antibiotic resistance, as well as the technologies currently used for their detection. Furthermore, we show that next generation sequencing may lead to faster characterization of virulence factors and prediction of the antibiotic resistance profile, thus contributing to personalized treatment and management of H. pylori-associated infections. With this new approach, more and permanent data will be generated at a lower cost, opening the future to new applications for H. pylori biomarker identification and antibiotic resistance prediction.
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Gottesmann M, Paraskevopoulou V, Mohammed A, Falcone FH, Hensel A. BabA and LPS inhibitors against Helicobacter pylori: pectins and pectin-like rhamnogalacturonans as adhesion blockers. Appl Microbiol Biotechnol 2019; 104:351-363. [PMID: 31768613 DOI: 10.1007/s00253-019-10234-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/15/2019] [Accepted: 10/31/2019] [Indexed: 12/17/2022]
Abstract
The first step in the development of Helicobacter pylori pathogenicity is receptor-mediated adhesion to gastric epithelium. Adhesins of H. pylori not only enable colonisation of the epithelium, with BabA interacting with Lewisb, but also interaction of lipopolysaccharide (LPS) with galectin-3 contributes to attachment of H. pylori to the host cells. Anti-adhesive compounds against H. pylori have been described, but specific analytical assays for pinpointing the interaction with BabA are limited. LPS-galectin-3 inhibitors have not been described until now. A sandwich ELISA with recombinant BabA547-6K was developed to investigate the interaction of BabA with Lewisb-HSA. Isothermal titration calorimetry gave thermodynamic information on the interaction between BabA, Lewisb-HSA and anti-adhesive compounds. A highly esterified rhamnogalacturonan from Abelmoschus esculentus inhibited the adhesion of H. pylori to adherent gastric adenocarcinoma (AGS) cells (IC50 550 μg/mL) and interacted with BabA (IC50 17 μg/mL). Pectins with similar rhamnogalacturonan structure showed weak anti-adhesive activity. Highly branched rhamnogalacturonans with low uronic acid content and high degree of esterification are potent BabA inhibitors. BabA represents a promising target for the development of anti-adhesive drugs against H. pylori. The rhamnogalacturonan influenced also the binding affinity of H. pylori to recombinant galectin-3 in a concentration-dependent manner with an IC50 of 222 μg/mL. Similar effects were obtained with pectin from apple fruits, while pectins from other sources were inactive.
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Affiliation(s)
- Maren Gottesmann
- Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Corrensstrasse 48, 48149, Münster, Germany
| | | | - Aymen Mohammed
- Institute for Parasitology, University of Giessen, Schubertstrasse 81, 35392, Giessen, Germany
| | - Franco H Falcone
- Institute for Parasitology, University of Giessen, Schubertstrasse 81, 35392, Giessen, Germany
| | - Andreas Hensel
- Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Corrensstrasse 48, 48149, Münster, Germany.
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4
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Abstract
Bacterial signal transduction systems are responsible for sensing environmental cues and adjusting the cellular behaviour and/or metabolism in response to these cues. They also monitor the intracellular conditions and the status of the cell envelope and the cytoplasmic membrane and trigger various stress responses to counteract adverse changes. This surveillance involves several classes of sensor proteins: histidine kinases; chemoreceptors; membrane components of the sugar phosphotransferase system; adenylate, diadenylate and diguanylate cyclases and certain cAMP, c-di-AMP and c-di-GMP phosphodiesterases; extracytoplasmic function sigma factors and Ser/Thr/Tyr protein kinases and phosphoprotein phosphatases. We have compiled a detailed listing of sensor proteins that are encoded in the genomes of Escherichia coli, Bacillus subtilis and 10 widespread pathogens: Chlamydia trachomatis, Haemophilus influenzae, Helicobacter pylori, Mycobacterium tuberculosis, Mycoplasma pneumoniae, Neisseria gonorrhoeae, Porphyromonas gingivalis, Rickettsia typhi, Streptococcus pyogenes and Treponema pallidum, and checked what, if anything, is known about their functions. This listing shows significant gaps in the understanding of which environmental and intracellular cues are perceived by these bacteria and which cellular responses are triggered by the changes in the respective parameters. A better understanding of bacterial preferences may suggest new ways to modulate the expression of virulence factors and therefore decrease the reliance on antibiotics to fight infection.
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
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5
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Abstract
BACKGROUND Helicobacter pylori is well adapted to colonize the epithelial surface of the human gastric mucosa and can cause persistent infections. In order to infect the gastric mucosa, it has to survive in the gastric acidic pH. This organism has well developed mechanisms to neutralize the effects of acidic pH. OBJECTIVE This review article was designed to summarize the various functional and molecular aspects by which the bacterium can combat and survive the gastric acidic pH in order to establish the persistent infections. METHODS We used the keywords (acid acclimation, gastric acidic environment, H. pylori and survival) in combination or alone for pubmed search of recent scientific literatures. One hundred and forty one papers published between 1989 and 2016 were sorted out. The articles published with only abstracts, other than in English language, case reports and reviews were excluded. RESULTS Many literatures describing the role of several factors in acid survival were found. Recently, the role of several other factors has been claimed to participate in acid survival. CONCLUSION In conclusion, this organism has well characterized mechanisms for acid survival.
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Affiliation(s)
- Shamshul Ansari
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Yufu, Japan
| | - Yoshio Yamaoka
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Yufu, Japan,Department of Medicine-Gastroenterology, Baylor College of Medicine, Houston, Texas, USA,Corresponding author: Yoshio Yamaoka, MD, PhD, Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama-machi, Yufu-City, Oita 879-5593, Japan, Tel: +81-97-586-5740; Fax: +81-97-586-5749,
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6
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BabA dependent binding of Helicobacter pylori to human gastric mucins cause aggregation that inhibits proliferation and is regulated via ArsS. Sci Rep 2017; 7:40656. [PMID: 28106125 PMCID: PMC5247751 DOI: 10.1038/srep40656] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 12/09/2016] [Indexed: 01/25/2023] Open
Abstract
Mucins in the gastric mucus layer carry a range of glycan structures, which vary between individuals, can have antimicrobial effect or act as ligands for Helicobacter pylori. Mucins from various individuals and disease states modulate H. pylori proliferation and adhesin gene expression differently. Here we investigate the relationship between adhesin mediated binding, aggregation, proliferation and adhesin gene expression using human gastric mucins and synthetic adhesin ligand conjugates. By combining measurements of optical density, bacterial metabolic activity and live/dead stains, we could distinguish bacterial aggregation from viability changes, enabling elucidation of mechanisms behind the anti-prolific effects that mucins can have. Binding of H. pylori to Leb-glycoconjugates inhibited the proliferation of the bacteria in a BabA dependent manner, similarly to the effect of mucins carrying Leb. Furthermore, deletion of arsS lead to a decrease in binding to Leb-glycoconjugates and Leb-decorated mucins, accompanied by decreased aggregation and absence of anti-prolific effect of mucins and Leb-glycoconjugates. Inhibition of proliferation caused by adhesin dependent binding to mucins, and the subsequent aggregation suggests a new role of mucins in the host defense against H. pylori. This aggregating trait of mucins may be useful to incorporate into the design of adhesin inhibitors and other disease intervention molecules.
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Abstract
Helicobacter pylori infects about 50 % of the world's population, causing at a minimum chronic gastritis. A subset of infected patients will ultimately develop gastric or duodenal ulcer disease, gastric adenocarcinoma, or MALT (mucosa-associated lymphoid tissue) lymphoma. Eradication of H. pylori requires complex regimens that include acid suppression and multiple antibiotics. The efficacy of treatment using what were once considered standard regimens have declined in recent years, mainly due to widespread development of antibiotic resistance. Addition of bismuth to standard triple therapy regimens, use of alternate antibiotics, or development of alternative regimens using known therapies in novel combinations have improved treatment efficacy in specific populations, but overall success of eradication remains less than ideal. Novel regimens under investigation either in vivo or in vitro, involving increased acid suppression ideally with fewer antibiotics or development of non-antibiotic treatment targets, show promise for future therapy.
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Affiliation(s)
- Elizabeth A Marcus
- Department of Pediatrics, DGSOM at UCLA, Los Angeles, CA, USA.
- VA GLAHS, 11301 Wilshire Blvd. Bldg 113 Rm 324, Los Angeles, CA, 90073, USA.
| | - George Sachs
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA, USA
- Department of Medicine, DGSOM at UCLA, Los Angeles, CA, USA
- VA GLAHS, 11301 Wilshire Blvd. Bldg 113 Rm 324, Los Angeles, CA, 90073, USA
| | - David R Scott
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA, USA
- VA GLAHS, 11301 Wilshire Blvd. Bldg 113 Rm 324, Los Angeles, CA, 90073, USA
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Kao CY, Sheu BS, Wu JJ. Helicobacter pylori infection: An overview of bacterial virulence factors and pathogenesis. Biomed J 2016; 39:14-23. [PMID: 27105595 PMCID: PMC6138426 DOI: 10.1016/j.bj.2015.06.002] [Citation(s) in RCA: 252] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 06/08/2015] [Indexed: 12/16/2022] Open
Abstract
Helicobacter pylori pathogenesis and disease outcomes are mediated by a complex interplay between bacterial virulence factors, host, and environmental factors. After H. pylori enters the host stomach, four steps are critical for bacteria to establish successful colonization, persistent infection, and disease pathogenesis: (1) Survival in the acidic stomach; (2) movement toward epithelium cells by flagella-mediated motility; (3) attachment to host cells by adhesins/receptors interaction; (4) causing tissue damage by toxin release. Over the past 20 years, the understanding of H. pylori pathogenesis has been improved by studies focusing on the host and bacterial factors through epidemiology researches and molecular mechanism investigations. These include studies identifying the roles of novel virulence factors and their association with different disease outcomes, especially the bacterial adhesins, cag pathogenicity island, and vacuolating cytotoxin. Recently, the development of large-scale screening methods, including proteomic, and transcriptomic tools, has been used to determine the complex gene regulatory networks in H. pylori. In addition, a more available complete genomic database of H. pylori strains isolated from patients with different gastrointestinal diseases worldwide is helpful to characterize this bacterium. This review highlights the key findings of H. pylori virulence factors reported over the past 20 years.
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Affiliation(s)
- Cheng-Yen Kao
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Bor-Shyang Sheu
- Department of Internal Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jiunn-Jong Wu
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan; Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei, Taiwan.
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9
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Marcus EA, Sachs G, Wen Y, Scott DR. Phosphorylation-dependent and Phosphorylation-independent Regulation of Helicobacter pylori Acid Acclimation by the ArsRS Two-component System. Helicobacter 2016; 21:69-81. [PMID: 25997502 PMCID: PMC4655181 DOI: 10.1111/hel.12235] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND The pH-sensitive Helicobacter pylori ArsRS two-component system (TCS) aids survival of this neutralophile in the gastric environment by directly sensing and responding to environmental acidity. ArsS is required for acid-induced trafficking of urease and its accessory proteins to the inner membrane, allowing rapid, urea-dependent cytoplasmic and periplasmic buffering. Expression of ArsR, but not its phosphorylation, is essential for bacterial viability. The aim of this study was to characterize the roles of ArsS and ArsR in the response of H. pylori to acid. MATERIALS AND METHODS Wild-type H. pylori and an arsR(D52N) phosphorylation-deficient strain were incubated at acidic or neutral pH. Gene and protein expression, survival, membrane trafficking of urease proteins, urease activity, and internal pH were studied. RESULTS Phosphorylation of ArsR is not required for acid survival. ArsS-driven trafficking of urease proteins to the membrane in acid, required for recovery of internal pH, is independent of ArsR phosphorylation. ArsR phosphorylation increases expression of the urease gene cluster, and the loss of negative feedback in a phosphorylation-deficient mutant leads to an increase in total urease activity. CONCLUSIONS ArsRS has a dual function in acid acclimation: regulation of urease trafficking to UreI at the cytoplasmic membrane, driven by ArsS, and regulation of urease gene cluster expression, driven by phosphorylation of ArsR. ArsS and ArsR work through phosphorylation-dependent and phosphorylation-independent regulatory mechanisms to impact acid acclimation and allow gastric colonization. Furthering understanding of the intricacies of acid acclimation will impact the future development of targeted, nonantibiotic treatment regimens.
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Affiliation(s)
- Elizabeth A. Marcus
- Department of Pediatrics, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
| | - George Sachs
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA
- Department of Medicine, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
| | - Yi Wen
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
| | - David R. Scott
- Department of Physiology, DGSOM at UCLA, Los Angeles, CA
- VA GLAHS, Los Angeles, CA
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10
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Marcus EA, Sachs G, Scott DR. Colloidal bismuth subcitrate impedes proton entry into Helicobacter pylori and increases the efficacy of growth-dependent antibiotics. Aliment Pharmacol Ther 2015; 42:922-33. [PMID: 26238858 PMCID: PMC4558396 DOI: 10.1111/apt.13346] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/08/2015] [Accepted: 07/15/2015] [Indexed: 12/14/2022]
Abstract
BACKGROUND Successful eradication of Helicobacter pylori is becoming more difficult, mainly due to emerging antibiotic resistance. Treatment regimens containing bismuth have increased efficacy, but the mechanism is unknown. Helicobacter pylori is a neutralophile adapted to survive the acidic gastric environment via acid acclimation, but demonstrates more robust growth at neutral pH. Many antibiotics used to treat H. pylori rely on bacterial growth. AIM To investigate the mechanism of increased efficacy of bismuth-containing H. pylori treatment regimens. METHODS RNAseq and qPCR, urease activity in permeabilised and intact bacteria, internal pH and membrane potential were measured with and without colloidal bismuth subcitrate (CBS). Bacterial survival was assessed with CBS and/or ampicillin. RESULTS Genes involved with metabolism and growth were upregulated in the presence of CBS at acidic pH. Urease activity of permeabilised H. pylori at pH 7.4 and 4.5 decreased in the presence of CBS, but intact urease activity decreased only at acidic pH. The fall in cytoplasmic pH with external acidification was diminished by CBS. The increase in membrane potential in response to urea addition at acidic medium pH was unaffected by CBS. The impact of CBS and ampicillin on H. pylori survival was greater than either agent alone. CONCLUSIONS Bismuth is not acting directly on urease or the urea channel. Colloidal bismuth subcitrate impedes proton entry into the bacteria, leading to a decrease in the expected fall in cytoplasmic pH. With cytoplasmic pH remaining within range for increased metabolic activity of a neutralophile, the efficacy of growth-dependent antibiotics is augmented.
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Affiliation(s)
| | - George Sachs
- Department of Physiology, Los Angeles, CA,Department of Medicine, DGSOM at UCLA, Los Angeles, CA,VA GLAHS, Los Angeles, CA
| | - David R. Scott
- Department of Physiology, Los Angeles, CA,VA GLAHS, Los Angeles, CA,Corresponding author, David R. Scott, UCLA/VA GLAHS, 11301 Wilshire Blvd, Bldg. 113 Rm. 324, Los Angeles, CA 90073, (310) 478-3711 x42046,
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11
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Carpenter BM, West AL, Gancz H, Servetas SL, Pich OQ, Gilbreath JJ, Hallinger DR, Forsyth MH, Merrell DS, Michel SLJ. Crosstalk between the HpArsRS two-component system and HpNikR is necessary for maximal activation of urease transcription. Front Microbiol 2015; 6:558. [PMID: 26124751 PMCID: PMC4464171 DOI: 10.3389/fmicb.2015.00558] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/20/2015] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori NikR (HpNikR) is a nickel dependent transcription factor that directly regulates a number of genes in this important gastric pathogen. One key gene that is regulated by HpNikR is ureA, which encodes for the urease enzyme. In vitro DNA binding studies of HpNikR with the ureA promoter (PureA) previously identified a recognition site that is required for high affinity protein/DNA binding. As a means to determine the in vivo significance of this recognition site and to identify the key DNA sequence determinants required for ureA transcription, herein, we have translated these in vitro results to analysis directly within H. pylori. Using a series of GFP reporter constructs in which the PureA DNA target was altered, in combination with mutant H. pylori strains deficient in key regulatory proteins, we confirmed the importance of the previously identified HpNikR recognition sequence for HpNikR-dependent ureA transcription. Moreover, we identified a second factor, the HpArsRS two-component system that was required for maximum transcription of ureA. While HpArsRS is known to regulate ureA in response to acid shock, it was previously thought to function independently of HpNikR and to have no role at neutral pH. However, our qPCR analysis of ureA expression in wildtype, ΔnikR and ΔarsS single mutants as well as a ΔarsS/nikR double mutant strain background showed reduced basal level expression of ureA when arsS was absent. Additionally, we determined that both HpNikR and HpArsRS were necessary for maximal expression of ureA under nickel, low pH and combined nickel and low pH stresses. In vitro studies of HpArsR-P with the PureA DNA target using florescence anisotropy confirmed a direct protein/DNA binding interaction. Together, these data support a model in which HpArsRS and HpNikR cooperatively interact to regulate ureA transcription under various environmental conditions. This is the first time that direct “cross-talk” between HpArsRS and HpNikR at neutral pH has been demonstrated.
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Affiliation(s)
- Beth M Carpenter
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Abby L West
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Maryland, USA
| | - Hanan Gancz
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Stephanie L Servetas
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Oscar Q Pich
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Jeremy J Gilbreath
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Daniel R Hallinger
- Department of Biology, The College of William and Mary Williamsburg, VA, USA
| | - Mark H Forsyth
- Department of Biology, The College of William and Mary Williamsburg, VA, USA
| | - D Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Sarah L J Michel
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Maryland, USA
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12
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Lund P, Tramonti A, De Biase D. Coping with low pH: molecular strategies in neutralophilic bacteria. FEMS Microbiol Rev 2014; 38:1091-125. [PMID: 24898062 DOI: 10.1111/1574-6976.12076] [Citation(s) in RCA: 272] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 02/26/2014] [Accepted: 03/14/2014] [Indexed: 12/31/2022] Open
Abstract
As part of their life cycle, neutralophilic bacteria are often exposed to varying environmental stresses, among which fluctuations in pH are the most frequent. In particular, acid environments can be encountered in many situations from fermented food to the gastric compartment of the animal host. Herein, we review the current knowledge of the molecular mechanisms adopted by a range of Gram-positive and Gram-negative bacteria, mostly those affecting human health, for coping with acid stress. Because organic and inorganic acids have deleterious effects on the activity of the biological macromolecules to the point of significantly reducing growth and even threatening their viability, it is not unexpected that neutralophilic bacteria have evolved a number of different protective mechanisms, which provide them with an advantage in otherwise life-threatening conditions. The overall logic of these is to protect the cell from the deleterious effects of a harmful level of protons. Among the most favoured mechanisms are the pumping out of protons, production of ammonia and proton-consuming decarboxylation reactions, as well as modifications of the lipid content in the membrane. Several examples are provided to describe mechanisms adopted to sense the external acidic pH. Particular attention is paid to Escherichia coli extreme acid resistance mechanisms, the activity of which ensure survival and may be directly linked to virulence.
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Affiliation(s)
- Peter Lund
- School of Biosciences, University of Birmingham, Birmingham, UK
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13
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Marcus EA, Vagin O, Tokhtaeva E, Sachs G, Scott DR. Helicobacter pylori impedes acid-induced tightening of gastric epithelial junctions. Am J Physiol Gastrointest Liver Physiol 2013; 305:G731-9. [PMID: 23989011 PMCID: PMC3840231 DOI: 10.1152/ajpgi.00209.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastric infection by Helicobacter pylori is the most common cause of ulcer disease and gastric cancer. The mechanism of progression from gastritis and inflammation to ulcers and cancer in a fraction of those infected is not definitively known. Significant acidity is unique to the gastric environment and is required for ulcer development. The interplay between gastric acidity and H. pylori pathogenesis is important in progression to advanced disease. The aim of this study was to characterize the impact of acid on gastric epithelial integrity and cytokine release and how H. pylori infection alters these responses. Human gastric epithelial (HGE-20) cells were grown on porous inserts, and survival, barrier function, and cytokine release were studied at various apical pH levels in the presence and absence of H. pylori. With apical acidity, gastric epithelial cells demonstrate increased barrier function, as evidenced by increased transepithelial electrical resistance (TEER) and decreased paracellular permeability. This effect is reduced in the presence of wild-type, but not urease knockout, H. pylori. The epithelial inflammatory response is also modulated by acidity and H. pylori infection. Without H. pylori, epithelial IL-8 release decreases in acid, while IL-6 release increases. In the presence of H. pylori, acidic pH diminishes the magnitude of the previously reported increase in IL-8 and IL-6 release. H. pylori interferes with the gastric epithelial response to acid, contributing to altered barrier function and inflammatory response. H. pylori diminishes acid-induced tightening of cell junctions in a urease-dependent manner, suggesting that local pH elevation promotes barrier compromise and progression to mucosal damage.
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Affiliation(s)
- Elizabeth A. Marcus
- 1Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; ,4Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California
| | - Olga Vagin
- 2Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; ,4Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California
| | - Elmira Tokhtaeva
- 2Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; ,4Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California
| | - George Sachs
- 2Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; ,3Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; and ,4Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California
| | - David R. Scott
- 2Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; ,4Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California
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14
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Abstract
BACKGROUND Helicobacter pylori, a neutralophile, colonizes the acidic environment of the human stomach by employing acid acclimation mechanisms that regulate periplasmic and cytoplasmic pH. The regulation of urease activity is central to acid acclimation. Inactive urease apoenzyme, UreA/B, requires nickel for activation. Accessory proteins UreE, F, G, and H are required for nickel insertion into apoenzyme. The ExbB/ExbD/TonB complex transfers energy from the inner to outer membrane, providing the driving force for nickel uptake. Therefore, the aim of this study was to determine the contribution of ExbD to pH homeostasis. MATERIALS AND METHODS A nonpolar exbD knockout was constructed and survival, growth, urease activity, and membrane potential were determined in comparison with wildtype. RESULTS Survival of the ΔexbD strain was significantly reduced at pH 3.0. Urease activity as a function of pH and UreI activation was similar to the wildtype strain, showing normal function of the proton-gated urea channel, UreI. The increase in total urease activity over time in acid seen in the wildtype strain was abolished in the ΔexbD strain, but recovered in the presence of supraphysiologic nickel concentrations, demonstrating that the effect of the ΔexbD mutant is due to loss of a necessary constant supply of nickel. In acid, ΔexbD also decreased its ability to maintain membrane potential and periplasmic buffering in the presence of urea. CONCLUSIONS ExbD is essential for maintenance of periplasmic buffering and membrane potential by transferring energy required for nickel uptake, making it a potential nonantibiotic target for H. pylori eradication.
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Affiliation(s)
- Elizabeth A. Marcus
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA,VA GLAHS, Los Angeles, CA
| | - George Sachs
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA,Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA,VA GLAHS, Los Angeles, CA
| | - David R. Scott
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA,VA GLAHS, Los Angeles, CA,Corresponding author: VA GLAHS, 11301 Wilshire Blvd, Bldg 113, Rm 324, Los Angeles, CA 90073, Phone: 310-478-3711 x42046, Fax: 310-312-9478,
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15
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Cid TP, Fernández MC, Benito Martínez S, Jones NL. Pathogenesis of Helicobacter pylori infection. Helicobacter 2013; 18 Suppl 1:12-7. [PMID: 24011239 DOI: 10.1111/hel.12076] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Helicobacter pylori infection and disease outcome are mediated by a complex interplay between bacterial, host, and environmental factors. Over the past year, our understanding of this complex interplay has been improved by a variety of studies focusing on both host and bacterial factors. These include studies assessing novel virulence factors as well as those most frequently associated with severity of disease outcome including cagA and the cag pathogenicity island, and the vacuolating cytotoxin. Several studies have focused on regulation of virulence factors by environmental factors. In addition, mechanisms by which bacterial virulence factors influence the host response and disease, by inducing epigenetic changes, autophagy and altered oxidative stress have also been elucidated. This review highlights key findings in the pathogenesis of H. pylori infection reported over the past year.
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Affiliation(s)
- Trinidad Parra Cid
- Unidad de Investigación, Hospital Universitario de Guadalajara, Guadalajara, Spain; CIBERehd (Centro de Investigación Biomédica en Red, Enfermedades Hepáticas y Digestivas), Madrid, Spain
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