A Gastric Pathogen Moves Chemotaxis in a New Direction

ABSTRACTFor almost 50 years,Escherichia colihas been the model for understanding how bacteria orient their movement in response to chemical cues, but recent studies of chemotaxis in other bacteria have revealed interesting variations from prevailing paradigms. Investigating the human pathogenHelicobacter pylori, Amieva and colleagues [mBio 2(4):e00098-11, 2011] discovered a new chemotaxis regulator, ChePep, which modulates swimming behavior through the canonical histidine-aspartate phosphorelay system. Functionally conserved among the epsilonproteobacteria, ChePep is essential forH. pylorito navigate deep into the stomach’s gastric glands and may be an attractive target for novel antibiotics.

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Galectin-3 Plays an Important Role in Innate Immunity to Gastric Infection by Helicobacter pylori

Infection and Immunity ◽

10.1128/iai.01299-15 ◽

2016 ◽

Vol 84 (4) ◽

pp. 1184-1193 ◽

Cited By ~ 35

Author(s):

Ah-Mee Park ◽

Satoru Hagiwara ◽

Daniel K. Hsu ◽

Fu-Tong Liu ◽

Osamu Yoshie

Keyword(s):

Innate Immunity ◽

Helicobacter Pylori ◽

Bacterial Cells ◽

Mucus Layer ◽

Iodide Uptake ◽

Gastric Glands ◽

Content Type ◽

Galectin 3 ◽

H Pylori ◽

Deficient Mice

We studied the role of galectin-3 (Gal3) in gastric infection byHelicobacter pylori. We first demonstrated that Gal3 was selectively expressed by gastric surface epithelial cells and abundantly secreted into the surface mucus layer. We next inoculatedH. pyloriSydney strain 1 into wild-type (WT) and Gal3-deficient mice using a stomach tube. At 2 weeks postinoculation, the bacterial cells were mostly trapped within the surface mucus layer in WT mice. In sharp contrast, they infiltrated deep into the gastric glands in Gal3-deficient mice. Bacterial loads in the gastric tissues were also much higher in Gal3-deficient mice than in WT mice. At 6 months postinoculation,H. pylorihad successfully colonized within the gastric glands of both WT and Gal3-deficient mice, although the bacterial loads were still higher in the latter. Furthermore, large lymphoid clusters mostly consisting of B cells were frequently observed in the gastric submucosa of Gal3-deficient mice.In vitro, peritoneal macrophages from Gal3-deficient mice were inefficient in killing engulfedH. pylori. Furthermore, recombinant Gal3 not only induced rapid aggregation ofH. pyloribut also exerted a potent bactericidal effect onH. pylorias revealed by propidium iodide uptake and a morphological shift from spiral to coccoid form. However, a minor fraction of bacterial cells, probably transient phase variants of Gal3-binding sugar moieties, escaped killing by Gal3. Collectively, our data demonstrate that Gal3 plays an important role in innate immunity to infection and colonization ofH. pylori.

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A Double Mutant Heat-Labile Toxin from Escherichia coli, LT(R192G/L211A), Is an Effective Mucosal Adjuvant for Vaccination against Helicobacter pylori Infection

Infection and Immunity ◽

10.1128/iai.01407-12 ◽

2013 ◽

Vol 81 (5) ◽

pp. 1532-1540 ◽

Cited By ~ 52

Author(s):

Louise Sjökvist Ottsjö ◽

Carl-Fredrik Flach ◽

John Clements ◽

Jan Holmgren ◽

Sukanya Raghavan

Keyword(s):

Escherichia Coli ◽

Helicobacter Pylori ◽

Immune Responses ◽

Double Mutant ◽

Bacterial Load ◽

Mucosal Vaccine ◽

Mucosal Adjuvant ◽

Content Type ◽

Heat Labile ◽

H Pylori

ABSTRACTHelicobacter pyloriinfection in the stomach is a common cause of peptic ulcer disease and is a strong risk factor for the development of gastric adenocarcinoma, yet no effective vaccine againstH. pyloriinfection is available to date. In mice, mucosal vaccination withH. pyloriantigens when given together with cholera toxin (CT) adjuvant, but not without adjuvant, can induce protective immune responses againstH. pyloriinfection. However, the toxicity of CT precludes its use as a mucosal adjuvant in humans. We evaluated a recently developed, essentially nontoxic double mutantEscherichia coliheat-labile toxin, LT(R192G/L211A) (dmLT), as a mucosal adjuvant in an experimentalH. pylorivaccine and compared it to CT in promoting immune responses and protection againstH. pyloriinfection in mice. Immunization via the sublingual or intragastric route withH. pylorilysate antigens and dmLT resulted in a significant decrease in bacterial load after challenge compared to that in unimmunized infection controls and to the same extent as when using CT as an adjuvant. Cellular immune responses in the sublingually immunized mice known to correlate with protection were also fully comparable when using dmLT and CT as adjuvants, resulting in enhancedin vitroproliferative and cytokine responses from spleen and mesenteric lymph node cells toH. pyloriantigens. Our results suggest that dmLT is an attractive adjuvant for inclusion in a mucosal vaccine againstH. pyloriinfection.

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The RNase J-Based RNA Degradosome Is Compartmentalized in the Gastric Pathogen Helicobacter pylori

mBio ◽

10.1128/mbio.01173-20 ◽

2020 ◽

Vol 11 (5) ◽

Author(s):

Alejandro Tejada-Arranz ◽

Eloïse Galtier ◽

Lamya El Mortaji ◽

Evelyne Turlin ◽

Dmitry Ershov ◽

...

Keyword(s):

Helicobacter Pylori ◽

Single Molecule ◽

Growth Phase ◽

Posttranscriptional Regulation ◽

Scaffolding Protein ◽

Content Type ◽

Gene Expression Control ◽

Gastric Pathogen ◽

Rna Degradosome ◽

H Pylori

ABSTRACT Posttranscriptional regulation is a major level of gene expression control in any cell. In bacteria, multiprotein machines called RNA degradosomes are central for RNA processing and degradation, and some were reported to be compartmentalized inside these organelleless cells. The minimal RNA degradosome of the important gastric pathogen Helicobacter pylori is composed of the essential ribonuclease RNase J and RhpA, its sole DEAD box RNA helicase, and plays a major role in the regulation of mRNA decay and adaptation to gastric colonization. Here, the subcellular localization of the H. pylori RNA degradosome was investigated using cellular fractionation and both confocal and superresolution microscopy. We established that RNase J and RhpA are peripheral inner membrane proteins and that this association was mediated neither by ribosomes nor by RNA nor by the RNase Y membrane protein. In live H. pylori cells, we observed that fluorescent RNase J and RhpA protein fusions assemble into nonpolar foci. We identified factors that regulate the formation of these foci without affecting the degradosome membrane association. Flotillin, a bacterial membrane scaffolding protein, and free RNA promote focus formation in H. pylori. Finally, RNase J-GFP (RNase J-green fluorescent protein) molecules and foci in cells were quantified by three-dimensional (3D) single-molecule fluorescence localization microscopy. The number and size of the RNase J foci were found to be scaled with growth phase and cell volume as previously reported for eukaryotic ribonucleoprotein granules. In conclusion, we propose that membrane compartmentalization and the regulated clustering of RNase J-based degradosome hubs represent important levels of control of their activity and specificity. IMPORTANCE Helicobacter pylori is a bacterial pathogen that chronically colonizes the stomach of half of the human population worldwide. Infection by H. pylori can lead to the development of gastric pathologies such as ulcers and adenocarcinoma, which causes up to 800,000 deaths in the world each year. Persistent colonization by H. pylori relies on regulation of the expression of adaptation-related genes. One major level of such control is posttranscriptional regulation, which, in H. pylori, largely relies on a multiprotein molecular machine, an RNA degradosome, that we previously discovered. In this study, we established that the two protein partners of this machine are associated with the membrane of H. pylori. Using cutting-edge microscopy, we showed that these complexes assemble into hubs whose formation is regulated by free RNA and scaled with bacterial size and growth phase. Organelleless cellular compartmentalization of molecular machines into hubs emerges as an important regulatory level in bacteria.

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Helicobacter pylori Requires TlpD-Driven Chemotaxis To Proliferate in the Antrum

Infection and Immunity ◽

10.1128/iai.00407-12 ◽

2012 ◽

Vol 80 (10) ◽

pp. 3713-3720 ◽

Cited By ~ 39

Author(s):

Annah S. Rolig ◽

James Shanks ◽

J. Elliot Carter ◽

Karen M. Ottemann

Keyword(s):

Helicobacter Pylori ◽

Transition Zone ◽

Chemical Cues ◽

Additional Analysis ◽

Wild Type ◽

Subsequent Growth ◽

Content Type ◽

Disease Outcomes ◽

Wild Type Phenotype ◽

H Pylori

ABSTRACTDifferent disease outcomes ofHelicobacter pyloriinfection correlate with distinct inflammation patterns. These different inflammatory distributions may be initiated by differences in bacterial localization. OneH. pyloriproperty known to affect murine stomach localization is chemotaxis, the ability to move in response to chemical cues. In this report, we used nonchemotactic mutants (Che−) to analyze whether chemotaxis is required for initial colonization of particular stomach regions or for subsequent growth therein. We found thatH. pyloribehaves differently in the corpus, antrum, and corpus-antrum transition zone subregions of the stomach. This outcome suggests that these regions contain unique chemotactic signals. In the corpus,H. pyloriutilizes chemotaxis for initial localization but not for subsequent growth. In contrast, in the antrum and the corpus-antrum transition zone, chemotaxis does not help initial colonization but does promote subsequent proliferation. To determine which chemoreceptor is responsible for the corpus-antrum phenotypes, we infected mice with strains lacking each chemoreceptor. Strains lacking TlpA, TlpB, or TlpC displayed only modest deviations from the wild-type phenotype, while strains lacking TlpD resembled the Che−mutant in their antral colonization defect and fared even worse than the Che−mutant in the corpus. Additional analysis showed that inflammation is worse in the antrum than in the corpus in both wild-type and Che−mutant infections. These results suggest that chemotaxis, specifically, that controlled by TlpD, is necessary forH. pylorito survive or grow in the environment of increased inflammation in the antrum.

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ChePep Controls Helicobacter pylori Infection of the Gastric Glands and Chemotaxis in the Epsilonproteobacteria

mBio ◽

10.1128/mbio.00098-11 ◽

2011 ◽

Vol 2 (4) ◽

Cited By ~ 61

Author(s):

Michael R. Howitt ◽

Josephine Y. Lee ◽

Paphavee Lertsethtakarn ◽

Roger Vogelmann ◽

Lydia-Marie Joubert ◽

...

Keyword(s):

Helicobacter Pylori ◽

Campylobacter Jejuni ◽

Deep Sea ◽

Hydrothermal Vent ◽

Bacterial Chemotaxis ◽

Peptic Ulcers ◽

Gastric Glands ◽

Content Type ◽

H Pylori ◽

Chemotaxis System

ABSTRACTMicrobes use directed motility to colonize harsh and dynamic environments. We discovered thatHelicobacter pyloristrains establish bacterial colonies deep in the gastric glands and identified a novel protein, ChePep, necessary to colonize this niche. ChePep is preferentially localized to the flagellar pole. Although mutants lacking ChePep have normal flagellar ultrastructure and are motile, they have a slight defect in swarming ability. By tracking the movement of single bacteria, we found that ∆ChePep mutants cannot control the rotation of their flagella and swim with abnormally frequent reversals. These mutants even sustain bursts of movement backwards with the flagella pulling the bacteria. Genetic analysis of the chemotaxis signaling pathway shows that ChePep regulates flagellar rotation through the chemotaxis system. By examiningH. pyloriwithin a microscopic pH gradient, we determined that ChePep is critical for regulating chemotactic behavior. ThechePepgene is unique to theEpsilonproteobacteriabut is found throughout this diverse group. We expressed ChePep from other members of theEpsilonproteobacteria, including the zoonotic pathogenCampylobacter jejuniand the deep sea hydrothermal vent inhabitantCaminibacter mediatlanticus, inH. pyloriand found that ChePep is functionally conserved across this class. ChePep represents a new family of chemotaxis regulators unique to theEpsilonproteobacteriaand illustrates the different strategies that microbes have evolved to control motility.IMPORTANCEHelicobacter pyloristrains infect half of all humans worldwide and contribute to the development of peptic ulcers and gastric cancer.H. pyloricannot survive within the acidic lumen of the stomach and uses flagella to actively swim to and colonize the protective mucus and epithelium. The chemotaxis system allowsH. pylorito navigate by regulating the rotation of its flagella. We identified a new protein, ChePep, which controls chemotaxis inH. pylori. ChePep mutants fail to colonize the gastric glands of mice and are completely outcompeted by normalH. pylori. Genes encoding ChePep are found only in the classEpsilonproteobacteria, which includes the human pathogenCampylobacter jejuniand environmental microbes like the deep-sea hydrothermal vent colonizerCaminibacter mediatlanticus, and we show that ChePep function is conserved in this class. Our study identifies a new colonization factor inH. pyloriand also provides insight into the control and evolution of bacterial chemotaxis.

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Twin-Arginine Translocation System in Helicobacter pylori: TatC, but Not TatB, Is Essential for Viability

mBio ◽

10.1128/mbio.01016-13 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 16

Author(s):

Stéphane L. Benoit ◽

Robert J. Maier

Keyword(s):

Helicobacter Pylori ◽

Homologous Recombination ◽

Signal Sequence ◽

Cell Envelope ◽

Wild Type ◽

Content Type ◽

Twin Arginine Translocation ◽

Tat System ◽

Gastric Pathogen ◽

H Pylori

ABSTRACT The twin-arginine translocation (Tat) system, needed to transport folded proteins across biological membranes, has not been characterized in the gastric pathogen Helicobacter pylori. Analysis of all H. pylori genome sequences available thus far reveals the presence of single copies of tatA, tatB, and tatC needed for the synthesis of a fully functional Tat system. Based on the presence of the twin-arginine hallmark in their signal sequence, only four H. pylori proteins appear to be Tat dependent: hydrogenase (HydA), catalase-associated protein (KapA), biotin sulfoxide reductase (BisC), and the ubiquinol cytochrome oxidoreductase Rieske protein (FbcF). In the present study, targeted mutations were aimed at tatA, tatB, tatC, or queA (downstream gene control). While double homologous recombination mutations in tatB and queA were easily obtained, attempts at disrupting tatA proved unsuccessful, while deletion of tatC led to partial mutants following single homologous recombination, with cells retaining a chromosomal copy of tatC. Double homologous recombination tatC mutants were obtained only when a plasmid-borne, isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible copy of tatC was introduced prior to transformation. These conditional tatC mutants could grow only in the presence of IPTG, suggesting that tatC is essential in H. pylori. tatB and tatC mutants had lower hydrogenase and catalase activities than the wild-type strain did, and the ability of tatC mutants to colonize mouse stomachs was severely affected compared to the wild type. Chromosomal complementation of tatC mutants restored hydrogenase and catalase activities to wild-type levels, and additional expression of tatC in wild-type cells resulted in elevated Tat-dependent enzyme activities. Unexpectedly, the tat strains had cell envelope defects. IMPORTANCE This work reports the first characterization of the twin-arginine translocation (Tat) system in the gastric pathogen Helicobacter pylori. While tatB mutants were easily obtained, only single-crossover partial tatC mutants or conditional tatC mutants could be generated, indicating that tatC is essential in H. pylori, a surprising finding given the fact that only four proteins are predicted to be translocated by the Tat system in this bacterium. The levels of activity of hydrogenase and catalase, two of the predicted Tat-dependent enzymes, were affected in these mutants. In addition, all tat mutants displayed cell envelope defects, and tatC mutants were deficient in mouse colonization.

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Magnesium Uptake by CorA Is Essential for Viability of the Gastric Pathogen Helicobacter pylori

Infection and Immunity ◽

10.1128/iai.70.7.3930-3934.2002 ◽

2002 ◽

Vol 70 (7) ◽

pp. 3930-3934 ◽

Cited By ~ 28

Author(s):

Jens Pfeiffer ◽

Johannes Guhl ◽

Barbara Waidner ◽

Manfred Kist ◽

Stefan Bereswill

Keyword(s):

Escherichia Coli ◽

Helicobacter Pylori ◽

Complementation Analysis ◽

Nickel Resistance ◽

Magnesium Uptake ◽

Gastric Pathogen ◽

H Pylori ◽

Cobalt And Nickel

ABSTRACT We show here that Mg2+ acquisition by CorA is essential for Helicobacter pylori in vitro, as corA mutants did not grow in media without Mg2+ supplementation. Complementation analysis performed with an Escherichia coli corA mutant revealed that H. pylori CorA transports nickel and cobalt in addition to Mg2+. However, Mg2+ is the dominant CorA substrate, as the corA mutation affected neither cobalt and nickel resistance nor nickel induction of urease in H. pylori. The drastic Mg2+ requirement (20 mM) of H. pylori corA mutants indicates that CorA plays a key role in the adaptation to the low-Mg2+ conditions predominant in the gastric environment.

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Agent-Based Modeling Demonstrates How Local Chemotactic Behavior Can Shape Biofilm Architecture

mSphere ◽

10.1128/msphere.00285-19 ◽

2019 ◽

Vol 4 (3) ◽

Cited By ~ 4

Author(s):

Emily G. Sweeney ◽

Andrew Nishida ◽

Alexandra Weston ◽

Maria S. Bañuelos ◽

Kristin Potter ◽

...

Keyword(s):

Helicobacter Pylori ◽

Three Dimensional ◽

Structural Features ◽

Agent Based Modeling ◽

Emergent Properties ◽

Cellular Interactions ◽

Biofilm Growth ◽

Content Type ◽

Agent Based ◽

H Pylori

ABSTRACTBacteria are often found living in aggregated multicellular communities known as biofilms. Biofilms are three-dimensional structures that confer distinct physical and biological properties to the collective of cells living within them. We used agent-based modeling to explore whether local cellular interactions were sufficient to give rise to global structural features of biofilms. Specifically, we asked whether chemorepulsion from a self-produced quorum-sensing molecule, autoinducer-2 (AI-2), was sufficient to recapitulate biofilm growth and cellular organization observed for biofilms ofHelicobacter pylori, a common bacterial resident of human stomachs. To carry out this modeling, we modified an existing platform, Individual-based Dynamics of Microbial Communities Simulator (iDynoMiCS), to incorporate three-dimensional chemotaxis, planktonic cells that could join or leave the biofilm structure, and cellular production of AI-2. We simulated biofilm growth of previously characterizedH. pyloristrains with various AI-2 production and sensing capacities. Using biologically plausible parameters, we were able to recapitulate both the variation in biofilm mass and cellular distributions observed with these strains. Specifically, the strains that were competent to chemotax away from AI-2 produced smaller and more heterogeneously spaced biofilms, whereas the AI-2 chemotaxis-defective strains produced larger and more homogeneously spaced biofilms. The model also provided new insights into the cellular demographics contributing to the biofilm patterning of each strain. Our analysis supports the idea that cellular interactions at small spatial and temporal scales are sufficient to give rise to larger-scale emergent properties of biofilms.IMPORTANCEMost bacteria exist in aggregated, three-dimensional structures called biofilms. Although biofilms play important ecological roles in natural and engineered settings, they can also pose societal problems, for example, when they grow in plumbing systems or on medical implants. Understanding the processes that promote the growth and disassembly of biofilms could lead to better strategies to manage these structures. We had previously shown thatHelicobacter pyloribacteria are repulsed by high concentrations of a self-produced molecule, AI-2, and thatH. pylorimutants deficient in AI-2 sensing form larger and more homogeneously spaced biofilms. Here, we used computer simulations of biofilm formation to show that localH. pyloribehavior of repulsion from high AI-2 could explain the overall architecture ofH. pyloribiofilms. Our findings demonstrate that it is possible to change global biofilm organization by manipulating local cell behaviors, which suggests that simple strategies targeting cells at local scales could be useful for controlling biofilms in industrial and medical settings.

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A Novel Line Immunoassay Based on Recombinant Virulence Factors Enables Highly Specific and Sensitive Serologic Diagnosis of Helicobacter pylori Infection

Clinical and Vaccine Immunology ◽

10.1128/cvi.00433-13 ◽

2013 ◽

Vol 20 (11) ◽

pp. 1703-1710 ◽

Cited By ~ 26

Author(s):

Luca Formichella ◽

Laura Romberg ◽

Christian Bolz ◽

Michael Vieth ◽

Michael Geppert ◽

...

Keyword(s):

Helicobacter Pylori ◽

Immune Responses ◽

Virulence Factors ◽

Gastrointestinal Disease ◽

Individual Risk ◽

Enzyme Linked Immunosorbent Assay ◽

Type I ◽

Serologic Test ◽

Content Type ◽

H Pylori

ABSTRACTHelicobacter pyloricolonizes half of the world's population, and infection can lead to ulcers, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. Serology is the only test applicable for large-scale, population-based screening, but current tests are hampered by a lack of sensitivity and/or specificity. Also, no serologic test allows the differentiation of type I and type II strains, which is important for predicting the clinical outcome.H. pylorivirulence factors have been associated with disease, but direct assessment of virulence factors requires invasive methods to obtain gastric biopsy specimens. Our work aimed at the development of a highly sensitive and specific, noninvasive serologic test to detect immune responses to importantH. pylorivirulence factors. This line immunoassay system (recomLine) is based on recombinant proteins. For this assay, six highly immunogenic virulence factors (CagA, VacA, GroEL, gGT, HcpC, and UreA) were expressed inEscherichia coli, purified, and immobilized to nitrocellulose membranes to detect serological immune responses in patient's sera. For the validation of the line assay, a cohort of 500 patients was screened, of which 290 (58.0%) wereH. pylorinegative and 210 (42.0%) were positive by histology. The assay showed sensitivity and specificity of 97.6% and 96.2%, respectively, compared to histology. In direct comparison to lysate blotting and enzyme-linked immunosorbent assay (ELISA), therecomLine assay had increased discriminatory power. For the assessment of individual risk for gastrointestinal disease, the test must be validated in a larger and defined patient cohort. Taking the data together, therecomLine assay provides a valuable tool for the diagnosis ofH. pyloriinfection.

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Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

Journal of Bacteriology ◽

10.1128/jb.02533-14 ◽

2015 ◽

Vol 197 (11) ◽

pp. 1921-1930 ◽

Cited By ~ 5

Author(s):

Jennifer Tsang ◽

Timothy R. Hoover

Keyword(s):

Helicobacter Pylori ◽

Basal Body ◽

Protein Interactions ◽

Transcript Levels ◽

Content Type ◽

Genes Encoding ◽

H Pylori ◽

Flagellar Biogenesis ◽

Flagellar Genes

ABSTRACTFlagellar biogenesis inHelicobacter pyloriis regulated by a transcriptional hierarchy governed by three sigma factors, RpoD (σ80), RpoN (σ54), and FliA (σ28), that temporally coordinates gene expression with the assembly of the flagellum. Previous studies showed that loss of flagellar protein export apparatus components inhibits transcription of flagellar genes. The FlgS/FlgR two-component system activates transcription of RpoN-dependent genes though an unknown mechanism. To understand better the extent to which flagellar gene regulation is coupled to flagellar assembly, we disrupted flagellar biogenesis at various points and determined how these mutations affected transcription of RpoN-dependent (flaBandflgE) and FliA-dependent (flaA) genes. The MS ring (encoded byfliF) is one of the earliest flagellar structures assembled. Deletion offliFresulted in the elimination of RpoN-dependent transcripts and an ∼4-fold decrease inflaAtranscript levels. FliH is a cytoplasmic protein that functions with the C ring protein FliN to shuttle substrates to the export apparatus. Deletions offliHand genes encoding C ring components (fliMandfliY) decreased transcript levels offlaBandflgEbut had little or no effect on transcript levels offlaA. Transcript levels offlaBandflgEwere elevated in mutants where genes encoding rod proteins (fliEandflgBC) were deleted, while transcript levels offlaAwas reduced ∼2-fold in both mutants. We propose that FlgS responds to an assembly checkpoint associated with the export apparatus and that FliH and one or more C ring component assist FlgS in engaging this flagellar structure.IMPORTANCEThe mechanisms used by bacteria to couple transcription of flagellar genes with assembly of the flagellum are poorly understood. The results from this study identified components of theH. pyloriflagellar basal body that either positively or negatively affect expression of RpoN-dependent flagellar genes. Some of these basal body proteins may interact directly with regulatory proteins that control transcription of theH. pyloriRpoN regulon, a hypothesis that can be tested by examining protein-protein interactionsin vitro.

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