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Åberg A, Gideonsson P, Bhat A, Ghosh P, Arnqvist A. Molecular insights into the fine-tuning of pH-dependent ArsR-mediated regulation of the SabA adhesin in Helicobacter pylori. Nucleic Acids Res 2024; 52:5572-5595. [PMID: 38499492 PMCID: PMC11162790 DOI: 10.1093/nar/gkae188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/28/2024] [Accepted: 03/12/2024] [Indexed: 03/20/2024] Open
Abstract
Adaptation to variations in pH is crucial for the ability of Helicobacter pylori to persist in the human stomach. The acid responsive two-component system ArsRS, constitutes the global regulon that responds to acidic conditions, but molecular details of how transcription is affected by the ArsR response regulator remains poorly understood. Using a combination of DNA-binding studies, in vitro transcription assays, and H. pylori mutants, we demonstrate that phosphorylated ArsR (ArsR-P) forms an active protein complex that binds DNA with high specificity in order to affect transcription. Our data showed that DNA topology is key for DNA binding. We found that AT-rich DNA sequences direct ArsR-P to specific sites and that DNA-bending proteins are important for the effect of ArsR-P on transcription regulation. The repression of sabA transcription is mediated by ArsR-P with the support of Hup and is affected by simple sequence repeats located upstream of the sabA promoter. Here stochastic events clearly contribute to the fine-tuning of pH-dependent gene regulation. Our results reveal important molecular aspects for how ArsR-P acts to repress transcription in response to acidic conditions. Such transcriptional control likely mediates shifts in bacterial positioning in the gastric mucus layer.
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Affiliation(s)
- Anna Åberg
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Pär Gideonsson
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Abhayprasad Bhat
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Prachetash Ghosh
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Anna Arnqvist
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
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2
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Xue J, Li W, Zhao Y, Wang L, Cheng P, Zhang L, Zheng Y, Zhang W, Bi Y, Chen Z, Jiang T, Sun Y. Antibiotic-induced ROS-mediated Fur allosterism contributes to Helicobacter pylori resistance by inhibiting arsR activation of mutS and mutY. Antimicrob Agents Chemother 2024; 68:e0167923. [PMID: 38386782 PMCID: PMC10989006 DOI: 10.1128/aac.01679-23] [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: 12/19/2023] [Accepted: 01/28/2024] [Indexed: 02/24/2024] Open
Abstract
The increasing antibiotic resistance of Helicobacter pylori primarily driven by genetic mutations poses a significant clinical challenge. Although previous research has suggested that antibiotics could induce genetic mutations in H. pylori, the molecular mechanisms regulating the antibiotic induction remain unclear. In this study, we applied various techniques (e.g., fluorescence microscopy, flow cytometry, and multifunctional microplate reader) to discover that three different types of antibiotics could induce the intracellular generation of reactive oxygen species (ROS) in H. pylori. It is well known that ROS, a critical factor contributing to bacterial drug resistance, not only induces damage to bacterial genomic DNA but also inhibits the expression of genes associated with DNA damage repair, thereby increasing the mutation rate of bacterial genes and leading to drug resistance. However, further research is needed to explore the molecular mechanisms underlying the ROS inhibition of the expression of DNA damage repair-related genes in H. pylori. In this work, we validated that ROS could trigger an allosteric change in the iron uptake regulatory protein Fur, causing its transition from apo-Fur to holo-Fur, repressing the expression of the regulatory protein ArsR, ultimately causing the down-regulation of key DNA damage repair genes (e.g., mutS and mutY); this cascade increased the genomic DNA mutation rate in H. pylori. This study unveils a novel mechanism of antibiotic-induced resistance in H. pylori, providing crucial insights for the prevention and control of antibiotic resistance in H. pylori.
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Affiliation(s)
- Junyuan Xue
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Wen Li
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Yican Zhao
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Liyuan Wang
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Peiyuan Cheng
- Department of Respiratory and Critical Care Medicine, The Second Hospital of Jilin University, Jilin, China
| | - Lu Zhang
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Yantong Zheng
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Wenxin Zhang
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
| | - Yakun Bi
- Science and Technology Management Center, The Maternal and Child Health Care Hospital of Guizhou Medical University, Guiyang, China
| | - Zhenghong Chen
- Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, China
| | - Ting Jiang
- Jiangsu Luye Diagnostic Technology, Wuxi, China
| | - Yundong Sun
- Department of Microbiology, Key Laboratory for Experimental Teratology of Ministry of Education, School of Basic Medical Science, Shandong University, Jinan, Shandong, China
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3
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Somiah T, Gebremariam HG, Zuo F, Smirnova K, Jonsson AB. Lactate causes downregulation of Helicobacter pylori adhesin genes sabA and labA while dampening the production of proinflammatory cytokines. Sci Rep 2022; 12:20064. [PMID: 36414643 PMCID: PMC9681763 DOI: 10.1038/s41598-022-24311-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022] Open
Abstract
Chronic inflammation induced by Helicobacter pylori is strongly associated with gastric cancer development, which is influenced by both bacterial virulence and host genetics. The sialic acid-binding adhesin SabA and the MUC5AC-binding adhesin LabA are important H. pylori virulence factors that facilitate adhesion of the bacterium, which is a crucial step in colonization. Lactate utilization has been reported to play a key role in the pathogenicity of different bacterial species. However, this is poorly understood in H. pylori. In this study, we investigated the effect of lactate on H. pylori adhesin gene expression and the regulation of host inflammatory cytokines. We show that the bacterial adhesins SabA and LabA were downregulated at the transcriptional level during incubation of H. pylori with lactate. Downregulation of sabA required the involvement of the two-component system ArsRS, while labA was regulated via the CheA/CheY system, indicating differences in the regulation of these genes in response to lactate. The levels of the proinflammatory cytokines TNF and IL-6 in H. pylori-stimulated macrophages were reduced when lactate was present. Interestingly, glucose did not prevent the secretion of these cytokines. Taken together, our data suggest that lactate affects H. pylori adhesin gene expression and the host response upon infection.
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Affiliation(s)
- Tanvi Somiah
- grid.10548.380000 0004 1936 9377Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 10691 Stockholm, Sweden
| | - Hanna G. Gebremariam
- grid.10548.380000 0004 1936 9377Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 10691 Stockholm, Sweden
| | - Fanglei Zuo
- grid.10548.380000 0004 1936 9377Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 10691 Stockholm, Sweden
| | - Ksenija Smirnova
- grid.10548.380000 0004 1936 9377Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 10691 Stockholm, Sweden
| | - Ann-Beth Jonsson
- grid.10548.380000 0004 1936 9377Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 10691 Stockholm, Sweden
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4
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Insights into the Orchestration of Gene Transcription Regulators in Helicobacter pylori. Int J Mol Sci 2022; 23:ijms232213688. [PMID: 36430169 PMCID: PMC9696931 DOI: 10.3390/ijms232213688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 10/31/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
Bacterial pathogens employ a general strategy to overcome host defenses by coordinating the virulence gene expression using dedicated regulatory systems that could raise intricate networks. During the last twenty years, many studies of Helicobacter pylori, a human pathogen responsible for various stomach diseases, have mainly focused on elucidating the mechanisms and functions of virulence factors. In parallel, numerous studies have focused on the molecular mechanisms that regulate gene transcription to attempt to understand the physiological changes of the bacterium during infection and adaptation to the environmental conditions it encounters. The number of regulatory proteins deduced from the genome sequence analyses responsible for the correct orchestration of gene transcription appears limited to 14 regulators and three sigma factors. Furthermore, evidence is accumulating for new and complex circuits regulating gene transcription and H. pylori virulence. Here, we focus on the molecular mechanisms used by H. pylori to control gene transcription as a function of the principal environmental changes.
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Casado J, Lanas Á, González A. Two-component regulatory systems in Helicobacter pylori and Campylobacter jejuni: Attractive targets for novel antibacterial drugs. Front Cell Infect Microbiol 2022; 12:977944. [PMID: 36093179 PMCID: PMC9449129 DOI: 10.3389/fcimb.2022.977944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Two-component regulatory systems (TCRS) are ubiquitous signal transduction mechanisms evolved by bacteria for sensing and adapting to the constant changes that occur in their environment. Typically consisting of two types of proteins, a membrane sensor kinase and an effector cytosolic response regulator, the TCRS modulate via transcriptional regulation a plethora of key physiological processes, thereby becoming essential for bacterial viability and/or pathogenicity and making them attractive targets for novel antibacterial drugs. Some members of the phylum Campylobacterota (formerly Epsilonproteobacteria), including Helicobacter pylori and Campylobacter jejuni, have been classified by WHO as “high priority pathogens” for research and development of new antimicrobials due to the rapid emergence and dissemination of resistance mechanisms against first-line antibiotics and the alarming increase of multidrug-resistant strains worldwide. Notably, these clinically relevant pathogens express a variety of TCRS and orphan response regulators, sometimes unique among its phylum, that control transcription, translation, energy metabolism and redox homeostasis, as well as the expression of relevant enzymes and virulence factors. In the present mini-review, we describe the signalling mechanisms and functional diversity of TCRS in H. pylori and C. jejuni, and provide an overview of the most recent findings in the use of these microbial molecules as potential novel therapeutic targets for the development of new antibiotics.
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Affiliation(s)
- Javier Casado
- Group of Translational Research in Digestive Diseases, Institute for Health Research Aragón (IIS Aragón), Zaragoza, Spain
- Department of Biochemistry and Molecular & Cellular Biology, University of Zaragoza, Zaragoza, Spain
| | - Ángel Lanas
- Group of Translational Research in Digestive Diseases, Institute for Health Research Aragón (IIS Aragón), Zaragoza, Spain
- Department of Medicine, Psychiatry and Dermatology, University of Zaragoza, Zaragoza, Spain
- Biomedical Research Networking Center in Hepatic and Digestive Diseases (CIBERehd), Madrid, Spain
- Digestive Diseases Service, University Clinic Hospital Lozano Blesa, Zaragoza, Spain
| | - Andrés González
- Group of Translational Research in Digestive Diseases, Institute for Health Research Aragón (IIS Aragón), Zaragoza, Spain
- Department of Medicine, Psychiatry and Dermatology, University of Zaragoza, Zaragoza, Spain
- Biomedical Research Networking Center in Hepatic and Digestive Diseases (CIBERehd), Madrid, Spain
- *Correspondence: Andrés González,
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6
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Xia X. Multiple regulatory mechanisms for pH homeostasis in the gastric pathogen, Helicobacter pylori. ADVANCES IN GENETICS 2022; 109:39-69. [PMID: 36334916 DOI: 10.1016/bs.adgen.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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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7
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Delineation of the pH-Responsive Regulon Controlled by the Helicobacter pylori ArsRS Two-Component System. Infect Immun 2021; 89:IAI.00597-20. [PMID: 33526561 DOI: 10.1128/iai.00597-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 01/09/2021] [Indexed: 12/22/2022] Open
Abstract
Helicobacter pylori encounters a wide range of pH within the human stomach. In a comparison of H. pylori cultured in vitro under neutral or acidic conditions, about 15% of genes are differentially expressed, and corresponding changes are detectable for many of the encoded proteins. The ArsRS two-component system (TCS), comprised of the sensor kinase ArsS and its cognate response regulator ArsR, has an important role in mediating pH-responsive changes in H. pylori gene expression. In this study, we sought to delineate the pH-responsive ArsRS regulon and further define the role of ArsR in pH-responsive gene expression. We compared H. pylori strains containing an intact ArsRS system with an arsS null mutant or strains containing site-specific mutations of a conserved aspartate residue (D52) in ArsR, which is phosphorylated in response to signals relayed by the cognate sensor kinase ArsS. We identified 178 genes that were pH-responsive in strains containing an intact ArsRS system but not in ΔarsS or arsR mutants. These constituents of the pH-responsive ArsRS regulon include genes involved in acid acclimatization (ureAB, amidases), oxidative stress responses (katA, sodB), transcriptional regulation related to iron or nickel homeostasis (fur, nikR), and genes encoding outer membrane proteins (including sabA, alpA, alpB, hopD [labA], and horA). When comparing H. pylori strains containing an intact ArsRS TCS with arsRS mutants, each cultured at neutral pH, relatively few genes are differentially expressed. Collectively, these data suggest that ArsRS-mediated gene regulation has an important role in H. pylori adaptation to changing pH conditions.
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8
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González A, Casado J, Chueca E, Salillas S, Velázquez-Campoy A, Sancho J, Lanas Á. Small Molecule Inhibitors of the Response Regulator ArsR Exhibit Bactericidal Activity against Helicobacter pylori. Microorganisms 2020; 8:microorganisms8040503. [PMID: 32244717 PMCID: PMC7232201 DOI: 10.3390/microorganisms8040503] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/19/2020] [Accepted: 03/30/2020] [Indexed: 12/16/2022] Open
Abstract
Helicobacter pylori is considered the most prevalent bacterial pathogen in humans. The increasing antibiotic resistance evolved by this microorganism has raised alarm bells worldwide due to the significant reduction in the eradication rates of traditional standard therapies. A major challenge in this antibiotic resistance crisis is the identification of novel microbial targets whose inhibitors can overcome the currently circulating resistome. In the present study, we have validated the use of the essential response regulator ArsR as a novel and promising therapeutic target against H. pylori infections. A high-throughput screening of a repurposing chemical library using a fluorescence-based thermal shift assay identified several ArsR binders. At least four of these low-molecular weight compounds noticeably inhibited the DNA binding activity of ArsR and showed bactericidal effects against antibiotic-resistant strains of H. pylori. Among the ArsR inhibitors, a human secondary bile acid, lithocholic acid, quickly destroyed H. pylori cells and exhibited partial synergistic action in combination with clarithromycin or levofloxacin, while the antimicrobial effect of this compound against representative members of the normal human microbiota such as Escherichia coli and Staphylococcus epidermidis appeared irrelevant. Our results enhance the battery of novel therapeutic tools against refractory infections caused by multidrug-resistant H. pylori strains.
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Affiliation(s)
- Andrés González
- Aragon Institute for Health Research (IIS Aragón), San Juan Bosco 13, 50009 Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Mariano Esquilor (Edif. I+D), 50018 Zaragoza, Spain
- Correspondence: ; Tel.: +34-976-762807
| | - Javier Casado
- Department of Biochemistry and Molecular & Cellular Biology, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Eduardo Chueca
- Aragon Institute for Health Research (IIS Aragón), San Juan Bosco 13, 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Monforte de Lemos 3-5, 28029 Madrid, Spain
| | - Sandra Salillas
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Mariano Esquilor (Edif. I+D), 50018 Zaragoza, Spain
- Department of Biochemistry and Molecular & Cellular Biology, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Aragon Institute for Health Research (IIS Aragón), San Juan Bosco 13, 50009 Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Mariano Esquilor (Edif. I+D), 50018 Zaragoza, Spain
- Department of Biochemistry and Molecular & Cellular Biology, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Monforte de Lemos 3-5, 28029 Madrid, Spain
- Fundación Agencia Aragonesa para la Investigación y el Desarrollo (ARAID), Government of Aragon, Ranillas 1-D, 50018 Zaragoza, Spain
| | - Javier Sancho
- Aragon Institute for Health Research (IIS Aragón), San Juan Bosco 13, 50009 Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Mariano Esquilor (Edif. I+D), 50018 Zaragoza, Spain
- Department of Biochemistry and Molecular & Cellular Biology, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Ángel Lanas
- Aragon Institute for Health Research (IIS Aragón), San Juan Bosco 13, 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Monforte de Lemos 3-5, 28029 Madrid, Spain
- Digestive Diseases Service, University Clinic Hospital Lozano Blesa, San Juan Bosco 15, 50009 Zaragoza, Spain
- Department of Medicine, Psychiatry and Dermatology, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
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9
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Servetas SL, Doster RS, Kim A, Windham IH, Cha JH, Gaddy JA, Merrell DS. ArsRS-Dependent Regulation of homB Contributes to Helicobacter pylori Biofilm Formation. Front Microbiol 2018; 9:1497. [PMID: 30116222 PMCID: PMC6083042 DOI: 10.3389/fmicb.2018.01497] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/18/2018] [Indexed: 12/14/2022] Open
Abstract
One elusive area in the Helicobacter pylori field is an understanding of why some infections result in gastric cancer, yet others persist asymptomatically for the life-span of the individual. Even before the genomic era, the high level of intraspecies diversity of H. pylori was well recognized and became an intriguing area of investigation with respect to disease progression. Of interest in this regard is the unique repertoire of over 60 outer membrane proteins (OMPs), several of which have been associated with disease outcome. Of these OMPs, the association between HomB and disease outcome varies based on the population being studied. While the molecular roles for some of the disease-associated OMPs have been evaluated, little is known about the role that HomB plays in the H. pylori lifecycle. Thus, herein we investigated homB expression, regulation, and contribution to biofilm formation. We found that in H. pylori strain G27, homB was expressed at a relatively low level until stationary phase. Furthermore, homB expression was suppressed at low pH in an ArsRS-dependent manner; mutation of arsRS resulted in increased homB transcript at all tested time-points. ArsRS regulation of homB appeared to be direct as purified ArsR was able to specifically bind to the homB promoter. This regulation, combined with our previous finding that ArsRS mutations lead to enhanced biofilm formation, led us to test the hypothesis that homB contributes to biofilm formation by H. pylori. Indeed, subsequent biofilm analysis using a crystal-violet quantification assay and scanning electron microscopy (SEM) revealed that loss of homB from hyper-biofilm forming strains resulted in reversion to a biofilm phenotype that mimicked wild-type. Furthermore, expression of homB in trans from a promoter that negated ArsRS regulation led to enhanced biofilm formation even in strains in which the chromosomal copy of homB had been deleted. Thus, homB is necessary for hyper-biofilm formation of ArsRS mutant strains and aberrant regulation of this gene is sufficient to induce a hyper-biofilm phenotype. In summary, these data suggest that the ArsRS-dependent regulation of OMPs such as HomB may be one mechanism by which ArsRS dictates biofilm development in a pH responsive manner.
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Affiliation(s)
- Stephanie L Servetas
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Ryan S Doster
- Department of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Aeryun Kim
- BK21 Plus Project, Department of Oral Biology, Oral Science Research Center, Yonsei University College of Dentistry, Seoul, South Korea
| | - Ian H Windham
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Jeong-Heon Cha
- BK21 Plus Project, Department of Oral Biology, Oral Science Research Center, Yonsei University College of Dentistry, Seoul, South Korea.,Department of Applied Life Science, The Graduate School, Yonsei University, Seoul, South Korea.,Microbiology and Molecular Biology Laboratory, Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jennifer A Gaddy
- Department of Medicine, Vanderbilt University, Nashville, TN, United States.,Tennessee Valley Healthcare Systems, Department of Veterans Affairs, Nashville, TN, United States
| | - D Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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10
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De la Cruz MA, Ares MA, von Bargen K, Panunzi LG, Martínez-Cruz J, Valdez-Salazar HA, Jiménez-Galicia C, Torres J. Gene Expression Profiling of Transcription Factors of Helicobacter pylori under Different Environmental Conditions. Front Microbiol 2017; 8:615. [PMID: 28443084 PMCID: PMC5385360 DOI: 10.3389/fmicb.2017.00615] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/27/2017] [Indexed: 12/22/2022] Open
Abstract
Helicobacter pylori is a Gram-negative bacterium that colonizes the human gastric mucosa and causes peptic ulcers and gastric carcinoma. H. pylori strain 26695 has a small genome (1.67 Mb), which codes for few known transcriptional regulators that control bacterial metabolism and virulence. We analyzed by qRT-PCR the expression of 16 transcriptional regulators in H. pylori 26695, including the three sigma factors under different environmental conditions. When bacteria were exposed to acidic pH, urea, nickel, or iron, the sigma factors were differentially expressed with a particularly strong induction of fliA. The regulatory genes hrcA, hup, and crdR were highly induced in the presence of urea, nickel, and iron. In terms of biofilm formation fliA, flgR, hp1021, fur, nikR, and crdR were induced in sessile bacteria. Transcriptional expression levels of rpoD, flgR, hspR, hp1043, and cheY were increased in contact with AGS epithelial cells. Kanamycin, chloramphenicol, and tetracycline increased or decreased expression of regulatory genes, showing that these antibiotics affect the transcription of H. pylori. Our data indicate that environmental cues which may be present in the human stomach modulate H. pylori transcription.
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Affiliation(s)
- Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - Miguel A Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | | | - Leonardo G Panunzi
- CNRS UMR7280, Inserm, U1104, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2Marseille, France
| | - Jessica Martínez-Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - Hilda A Valdez-Salazar
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - César Jiménez-Galicia
- Laboratorio Clínico, Unidad Médica de Alta Especialidad, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - Javier Torres
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
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11
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Lin CS, Tsai YH, Chang CJ, Tseng SF, Wu TR, Lu CC, Wu TS, Lu JJ, Horng JT, Martel J, Ojcius DM, Lai HC, Young JD. An iron detection system determines bacterial swarming initiation and biofilm formation. Sci Rep 2016; 6:36747. [PMID: 27845335 PMCID: PMC5109203 DOI: 10.1038/srep36747] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/20/2016] [Indexed: 11/30/2022] Open
Abstract
Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising a two-component system (TCS) and the TCS-regulated iron chelator 2-isocyano-6,7-dihydroxycoumarin (ICDH-Coumarin) that directly senses and modulates environmental ferric iron (Fe3+) availability to determine swarming initiation and biofilm formation. We demonstrate that the two-component system RssA-RssB (RssAB) directly senses environmental ferric iron (Fe3+) and transcriptionally modulates biosynthesis of flagella and the iron chelator ICDH-Coumarin whose production requires the pvc cluster. Addition of Fe3+, or loss of ICDH-Coumarin due to pvc deletion results in prolonged RssAB signaling activation, leading to delayed swarming initiation and increased biofilm formation. We further show that ICDH-Coumarin is able to chelate Fe3+ to switch off RssAB signaling, triggering swarming initiation and biofilm reduction. Our findings reveal a novel cellular system that senses iron levels to regulate bacterial surface lifestyle.
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Affiliation(s)
- Chuan-Sheng Lin
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Biochemistry and Molecular Biology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Yu-Huan Tsai
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Chih-Jung Chang
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Shun-Fu Tseng
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Tsung-Ru Wu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Chia-Chen Lu
- Department of Respiratory Therapy, Fu Jen University, New Taipei City, Taiwan, Republic of China
| | - Ting-Shu Wu
- Department of Internal Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
| | - Jang-Jih Lu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
| | - Jim-Tong Horng
- Department of Biochemistry and Molecular Biology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Jan Martel
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - David M. Ojcius
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, United States of America
| | - Hsin-Chih Lai
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
- Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China
- Graduate Institute of Health Industry Technology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China
| | - John D. Young
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, United States of America
- Biochemical Engineering Research Center, Ming Chi University of Technology, New Taipei City, Taiwan, Republic of China
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12
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Servetas SL, Carpenter BM, Haley KP, Gilbreath JJ, Gaddy JA, Merrell DS. Characterization of Key Helicobacter pylori Regulators Identifies a Role for ArsRS in Biofilm Formation. J Bacteriol 2016; 198:2536-48. [PMID: 27432830 PMCID: PMC4999924 DOI: 10.1128/jb.00324-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 07/07/2016] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Helicobacter pylori must be able to rapidly respond to fluctuating conditions within the stomach. Despite this need for constant adaptation, H. pylori encodes few regulatory proteins. Of the identified regulators, the ferric uptake regulator (Fur), the nickel response regulator (NikR), and the two-component acid response system (ArsRS) are each paramount to the success of this pathogen. While numerous studies have individually examined these regulatory proteins, little is known about their combined effect. Therefore, we constructed a series of isogenic mutant strains that contained all possible single, double, and triple regulatory mutations in Fur, NikR, and ArsS. A growth curve analysis revealed minor variation in growth kinetics across the strains; these were most pronounced in the triple mutant and in strains lacking ArsS. Visual analysis showed that strains lacking ArsS formed large aggregates and a biofilm-like matrix at the air-liquid interface. Biofilm quantification using crystal violet assays and visualization via scanning electron microscopy (SEM) showed that all strains lacking ArsS or containing a nonphosphorylatable form of ArsR (ArsR-D52N mutant) formed significantly more biofilm than the wild-type strain. Molecular characterization of biofilm formation showed that strains containing mutations in the ArsRS pathway displayed increased levels of cell aggregation and adherence, both of which are key to biofilm development. Furthermore, SEM analysis revealed prevalent coccoid cells and extracellular matrix formation in the ArsR-D52N, ΔnikR ΔarsS, and Δfur ΔnikR ΔarsS mutant strains, suggesting that these strains may have an exacerbated stress response that further contributes to biofilm formation. Thus, H. pylori ArsRS has a previously unrecognized role in biofilm formation. IMPORTANCE Despite a paucity of regulatory proteins, adaptation is key to the survival of H. pylori within the stomach. While prior studies have focused on individual regulatory proteins, such as Fur, NikR, and ArsRS, few studies have examined the combined effect of these factors. Analysis of isogenic mutant strains that contained all possible single, double, and triple regulatory mutations in Fur, NikR, and ArsS revealed a previously unrecognized role for the acid-responsive two-component system ArsRS in biofilm formation.
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Affiliation(s)
- Stephanie L Servetas
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Beth M Carpenter
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Kathryn P Haley
- Department of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Jeremy J Gilbreath
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Jennifer A Gaddy
- Department of Medicine, Vanderbilt University, Nashville, Tennessee, USA Tennessee Valley Health Care Systems, U.S. Department of Veterans Affairs, Nashville, Tennessee, USA
| | - D Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
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13
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Roncarati D, Pelliciari S, Doniselli N, Maggi S, Vannini A, Valzania L, Mazzei L, Zambelli B, Rivetti C, Danielli A. Metal-responsive promoter DNA compaction by the ferric uptake regulator. Nat Commun 2016; 7:12593. [PMID: 27558202 PMCID: PMC5007355 DOI: 10.1038/ncomms12593] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 07/13/2016] [Indexed: 01/09/2023] Open
Abstract
Short-range DNA looping has been proposed to affect promoter activity in many bacterial species and operator configurations, but only few examples have been experimentally investigated in molecular detail. Here we present evidence for a metal-responsive DNA condensation mechanism controlled by the Helicobacter pylori ferric uptake regulator (Fur), an orthologue of the widespread Fur family of prokaryotic metal-dependent regulators. H. pylori Fur represses the transcription of the essential arsRS acid acclimation operon through iron-responsive oligomerization and DNA compaction, encasing the arsR transcriptional start site in a repressive macromolecular complex. A second metal-dependent regulator NikR functions as nickel-dependent anti-repressor at this promoter, antagonizing the binding of Fur to the operator elements responsible for the DNA condensation. The results allow unifying H. pylori metal ion homeostasis and acid acclimation in a mechanistically coherent model, and demonstrate, for the first time, the existence of a selective metal-responsive DNA compaction mechanism controlling bacterial transcriptional regulation. The Fur protein regulates transcription of bacterial genes in response to metal ions. Here, the authors show that the Fur protein from Helicobacter pylori represses transcription by iron-responsive oligomerization and DNA compaction, encasing the transcriptional start site in a macromolecular complex.
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Affiliation(s)
- Davide Roncarati
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
| | - Simone Pelliciari
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
| | - Nicola Doniselli
- Department of Life Sciences, University of Parma, 43124 Parma, Italy
| | - Stefano Maggi
- Department of Life Sciences, University of Parma, 43124 Parma, Italy
| | - Andrea Vannini
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
| | - Luca Valzania
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
| | - Luca Mazzei
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
| | - Barbara Zambelli
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
| | - Claudio Rivetti
- Department of Life Sciences, University of Parma, 43124 Parma, Italy
| | - Alberto Danielli
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
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14
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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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15
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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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16
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A novel DNA-binding protein plays an important role in Helicobacter pylori stress tolerance and survival in the host. J Bacteriol 2014; 197:973-82. [PMID: 25535274 DOI: 10.1128/jb.02489-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The gastric pathogen Helicobacter pylori must combat chronic acid and oxidative stress. It does so via many mechanisms, including macromolecule repair and gene regulation. Mitomycin C-sensitive clones from a transposon mutagenesis library were screened. One sensitive strain contained the insertion element at the locus of hp119, a hypothetical gene. No homologous gene exists in any (non-H. pylori) organism. Nevertheless, the predicted protein has some features characteristic of histone-like proteins, and we showed that purified HP119 protein is a DNA-binding protein. A Δhp119 strain was markedly more sensitive (viability loss) to acid or to air exposure, and these phenotypes were restored to wild-type (WT) attributes upon complementation of the mutant with the wild-type version of hp119 at a separate chromosomal locus. The mutant strain was approximately 10-fold more sensitive to macrophage-mediated killing than the parent or the complemented strain. Of 12 mice inoculated with the wild type, all contained H. pylori, whereas 5 of 12 mice contained the mutant strain; the mean colonization numbers were 158-fold less for the mutant strain. A proteomic (two-dimensional PAGE with mass spectrometric analysis) comparison between the Δhp119 mutant and the WT strain under oxidative stress conditions revealed a number of important antioxidant protein differences; SodB, Tpx, TrxR, and NapA, as well as the peptidoglycan deacetylase PgdA, were significantly less expressed in the Δhp119 mutant than in the WT strain. This study identified HP119 as a putative histone-like DNA-binding protein and showed that it plays an important role in Helicobacter pylori stress tolerance and survival in the host.
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17
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Njoroge JW, Sperandio V. Interference with Bacterial Cell-to-Cell Chemical Signaling in Development of New Anti-Infectives. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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18
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Scott JC, Klein BA, Duran-Pinedo A, Hu L, Duncan MJ. A two-component system regulates hemin acquisition in Porphyromonas gingivalis. PLoS One 2013; 8:e73351. [PMID: 24039921 PMCID: PMC3764172 DOI: 10.1371/journal.pone.0073351] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 07/17/2013] [Indexed: 01/19/2023] Open
Abstract
Porphyromonas gingivalis is a Gram-negative oral anaerobe associated with infection of the periodontia. The organism has a small number of two-component signal transduction systems, and after comparing genome sequences of strains W83 and ATCC 33277 we discovered that the latter was mutant in histidine kinase (PGN_0752), while the cognate response regulator (PGN_0753) remained intact. Microarray-based transcriptional profiling and ChIP-seq assays were carried out with an ATCC 33277 transconjugant containing the functional histidine kinase from strain W83 (PG0719). The data showed that the regulon of this signal transduction system contained genes that were involved in hemin acquisition, including gingipains, at least three transport systems, as well as being self-regulated. Direct regulation by the response regulator was confirmed by electrophoretic mobility shift assays. In addition, the system appears to be activated by hemin and the regulator acts as both an activator and repressor.
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Affiliation(s)
- Jodie C. Scott
- Department of Microbiology, The Forsyth Institute, Cambridge, Massachusetts, United States of America
| | - Brian A. Klein
- Department of Molecular Biology and Microbiology, Tufts University Sackler School of Biomedical Sciences, Boston, Massachusetts, United States of America
| | - Ana Duran-Pinedo
- Department of Microbiology, The Forsyth Institute, Cambridge, Massachusetts, United States of America
| | - Linden Hu
- Division of Geographic Medicine and Infectious Disease, Tufts Medical Center, Boston, Massachusetts, United States of America
| | - Margaret J. Duncan
- Department of Microbiology, The Forsyth Institute, Cambridge, Massachusetts, United States of America
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19
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Mutations to essential orphan response regulator HP1043 of Helicobacter pylori result in growth-stage regulatory defects. Infect Immun 2013; 81:1439-49. [PMID: 23429531 DOI: 10.1128/iai.01193-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Helicobacter pylori establishes lifelong infections of the gastric mucosa, a niche considered hostile to most microbes. While responses to gastric acidity and local inflammation are understood, little is known as to how they are integrated into homeostatic control of cell division and growth-stage gene expression. Here we investigate the essential orphan response regulator HP1043, a member of the OmpR/PhoB subfamily of transcriptional regulators that is unique to the Epsilonproteobacteria and that lacks phosphorylation domains. To test the hypothesis that conformational changes in the homodimer might lead to defects in gene expression, we sought mutations that might alter DNA-binding efficiency. Two introduced mutations (C215S, C221S) C terminal to the DNA-binding domain of HP1043 (HP1043CC11) resulted in a 2-fold higher affinity for its own promoter by footprinting. Modeling studies with the crystal structure of HP1043 suggested that C215S might affect the helix-turn-helix domain. Genomic replacement of the hp1043 allele with the hp1043CC11 mutant allele resulted in a 2-fold decrease in protein levels, despite a dramatic increase in mRNA. The mutations did not affect in vitro growth rates or colonization efficiency in a mouse model. Proteomic profiling (CC11 mutant strain versus wild type) identified many expression differences, and quantitative PCR further revealed that 11 out of 12 examined genes had lost growth-stage regulation and that 6 of the genes contained HP1043 binding consensus sequences within the promoter regions (fur, cagA, cag23, flhA, flip, and napA). Our studies show that mutations that affect DNA-binding affinity can be used to identify new members of the HP1043 regulon.
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20
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Fur activates expression of the 2-oxoglutarate oxidoreductase genes (oorDABC) in Helicobacter pylori. J Bacteriol 2012; 194:6490-7. [PMID: 23002221 DOI: 10.1128/jb.01226-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Helicobacter pylori is a highly successful pathogen that colonizes the gastric mucosa of ∼50% of the world's population. Within this colonization niche, the bacteria encounter large fluctuations in nutrient availability. As such, it is critical that this organism regulate expression of key metabolic enzymes so that they are present when environmental conditions are optimal for growth. One such enzyme is the 2-oxoglutarate (α-ketoglutarate) oxidoreductase (OOR), which catalyzes the conversion of α-ketoglutarate to succinyl coenzyme A (succinyl-CoA) and CO(2). Previous studies from our group suggested that the genes that encode the OOR are activated by iron-bound Fur (Fe-Fur); microarray analysis showed that expression of oorD, oorA, and oorC was altered in a fur mutant strain of H. pylori. The goal of the present work was to more thoroughly characterize expression of the oorDABC genes in H. pylori as well as to define the role of Fe-Fur in this process. Here we show that these four genes are cotranscribed as an operon and that expression of the operon is decreased in a fur mutant strain. Transcriptional start site mapping and promoter analysis revealed the presence of a canonical extended -10 element but a poorly conserved -35 element upstream of the +1. Additionally, we identified a conserved Fur binding sequence ∼130 bp upstream of the transcriptional start site. Transcriptional analysis using promoter fusions revealed that this binding sequence was required for Fe-Fur-mediated activation. Finally, fluorescence anisotropy assays indicate that Fe-Fur specifically bound this Fur box with a relatively high affinity (dissociation constant [K(d)] = 200 nM). These findings provide novel insight into the genetic regulation of a key metabolic enzyme and add to our understanding of the diverse roles Fur plays in gene regulation in H. pylori.
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21
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Hallinger DR, Romero-Gallo J, Peek RM, Forsyth MH. Polymorphisms of the acid sensing histidine kinase gene arsS in Helicobacter pylori populations from anatomically distinct gastric sites. Microb Pathog 2012; 53:227-33. [PMID: 22940419 DOI: 10.1016/j.micpath.2012.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 08/14/2012] [Indexed: 12/24/2022]
Abstract
Phase variation is frequently utilized by bacterial species to affect gene expression such that phenotypic variants are maintained within populations, ensuring survival as environmental or host conditions change. Unusual among Helicobacter pylori phase variable or contingency genes is arsS, encoding a sensory histidine kinase involved in the acid acclimation of the organism. The presence of a 3' homopolymeric cytosine tract of variable length in arsS among Helicobacter pylori strains allows for the expression of various functional ArsS isoforms, differing in carboxy-terminal protein domains. In this study, we analyzed this 3'arsS region via amplified fragment length polymorphism (AFLP) and sequencing analyses for H. pylori populations from 3 different gastric sites of 12 patients. Our data indicate the presence of multiple arsS alleles within each population of H. pylori derived from the gastric antrum, cardia, or corpus of these patients. We also show that H. pylori, derived from the same anatomical site and patient, are predicted to express multiple ArsS isoforms in each population investigated. Furthermore, we identify a polymorphic deletion within arsS that generates another alternate ArsS C-terminal end. These findings suggest that four C-terminal variations of ArsS adds to the complexity of the ArsRS acid adaptation mechanism as a whole and may influence the ability of H. pylori to persist in the gastric niche for decades.
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Affiliation(s)
- Daniel R Hallinger
- Department of Biology, The College of William and Mary, Integrated Science Center 3051, Williamsburg, VA 23185, USA
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22
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Utsumi R, Igarashi M. [Two-component signal transduction as attractive drug targets in pathogenic bacteria]. YAKUGAKU ZASSHI 2012; 132:51-8. [PMID: 22214580 DOI: 10.1248/yakushi.132.51] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gene clusters contributing to processes such as cell growth and pathogenicity are often controlled by two-component signal transduction systems (TCSs). TCS consists of a histidine kinase (HK) and a response regulator (RR). TCSs are attractive as drug targets for antimicrobials because many HK and RR genes are coded on the bacterial genome though few are found in lower eukaryotes. The HK/RR signal transduction system is distinct from serine/threonine and tyrosine phosphorylation in higher eukaryotes. Specific inhibitors against TCS systems work differently from conventional antibiotics, and developing them into new drugs that are effective against various drug-resistant bacteria may be possible. Furthermore, inhibitors of TCSs that control virulence factors may reduce virulence without killing the pathogenic bacteria. Previous TCS inhibitors targeting the kinase domain of the histidine kinase sensor suffered from poor selectivity. Recent TCS inhibitors, however, target the sensory domains of the sensors blocking the quorum sensing system, or target the essential response regulator. These new targets are introduced, together with several specific TCSs that have the potential to serve as effective drug targets.
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Affiliation(s)
- Ryutaro Utsumi
- Department of Bioscience, Graduate School of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan.
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23
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Fritsch F, Mauder N, Williams T, Weiser J, Oberle M, Beier D. The cell envelope stress response mediated by the LiaFSRLm three-component system of Listeria monocytogenes is controlled via the phosphatase activity of the bifunctional histidine kinase LiaSLm. MICROBIOLOGY-SGM 2010; 157:373-386. [PMID: 21030435 DOI: 10.1099/mic.0.044776-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Most members of the phylum Firmicutes harbour a two-component system (TCS), LiaSR, which is involved in the response to cell envelope stress elicited most notably by inhibitors of the lipid II cycle. In all LiaSR systems studied in detail, LiaSR-mediated signal transduction has been shown to be negatively controlled by a membrane protein, LiaF, encoded upstream of liaSR. In this study we have analysed the LiaSR orthologue of Listeria monocytogenes (LiaSR(Lm)). Whole-genome transcriptional profiling indicated that activation of LiaSR(Lm) results in a remodelling of the cell envelope via the massive upregulation of membrane-associated and extracytoplasmic proteins in the presence of inducing stimuli. As shown for other LiaSR TCSs, LiaSR(Lm) is activated by cell wall-active antibiotics. We demonstrate that the level of phosphorylated LiaR(Lm), which is required for the induction of the LiaSR(Lm) regulon, is controlled by the interplay between the histidine kinase and phosphatase activities of the bifunctional sensor protein LiaS(Lm). Our data suggest that the phosphatase activity of LiaS(Lm) is stimulated by LiaF(Lm) in the absence of cell envelope stress.
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Affiliation(s)
- Frederike Fritsch
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Norman Mauder
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Tatjana Williams
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Julia Weiser
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Markus Oberle
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Dagmar Beier
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Built shallow to maintain homeostasis and persistent infection: insight into the transcriptional regulatory network of the gastric human pathogen Helicobacter pylori. PLoS Pathog 2010; 6:e1000938. [PMID: 20548942 PMCID: PMC2883586 DOI: 10.1371/journal.ppat.1000938] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Transcriptional regulatory networks (TRNs) transduce environmental signals into coordinated output expression of the genome. Accordingly, they are central for the adaptation of bacteria to their living environments and in host-pathogen interactions. Few attempts have been made to describe a TRN for a human pathogen, because even in model organisms, such as Escherichia coli, the analysis is hindered by the large number of transcription factors involved. In light of the paucity of regulators, the gastric human pathogen Helicobacter pylori represents a very appealing system for understanding how bacterial TRNs are wired up to support infection in the host. Herein, we review and analyze the available molecular and "-omic" data in a coherent ensemble, including protein-DNA and protein-protein interactions relevant for transcriptional control of pathogenic responses. The analysis covers approximately 80% of the annotated H. pylori regulators, and provides to our knowledge the first in-depth description of a TRN for an important pathogen. The emerging picture indicates a shallow TRN, made of four main modules (origons) that process the physiological responses needed to colonize the gastric niche. Specific network motifs confer distinct transcriptional response dynamics to the TRN, while long regulatory cascades are absent. Rather than having a plethora of specialized regulators, the TRN of H. pylori appears to transduce separate environmental inputs by using different combinations of a small set of regulators.
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25
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Wachino JI, Shibayama K, Suzuki S, Yamane K, Mori S, Arakawa Y. Profile of Expression of Helicobacter pylori gamma-glutamyltranspeptidase. Helicobacter 2010; 15:184-92. [PMID: 20557359 DOI: 10.1111/j.1523-5378.2010.00755.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Helicobacter pylori produces gamma-glutamyltranspeptidase (GGT), a potential virulence factor involved in induction of host cell apoptosis. Regulation of the production of this protein is not known. METHODS The transcription start sites were determined by primer extension analysis. Transcription level of the GGT gene was examined by measuring the mRNA by RT-PCR and expression level of GGT protein was examined by Western blot analysis under different conditions. RESULTS Two transcription start sites were identified; thymine at 78-bp upstream and adenine at 79-bp upstream from the ATG codon of the GGT gene. There was a possible -10 consensus promoter sequence (ATTAAT), but no apparent -35 consensus sequence was found. The transcription of the mRNA and the expression of the protein were at almost constant level during the course of culture. The mRNA level increased by exposure to low pH; however, the actual protein expression level remained almost constant. Addition of glutamine or glutamate did not affect the mRNA level and the protein expression level to a remarkable degree, nor did co-culture with AGS cells affect the GGT activity level. CONCLUSION It was suggested that H. pylori GGT is constitutively expressed under various conditions.
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Affiliation(s)
- Jun-Ichi Wachino
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
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26
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Analysis of protein expression regulated by the Helicobacter pylori ArsRS two-component signal transduction system. J Bacteriol 2010; 192:2034-43. [PMID: 20154125 DOI: 10.1128/jb.01703-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Previous studies have shown that the Helicobacter pylori ArsRS two-component signal transduction system contributes to acid-responsive gene expression. To identify additional members of the ArsRS regulon and further investigate the regulatory role of the ArsRS system, we analyzed protein expression in wild-type and arsS null mutant strains. Numerous proteins were differentially expressed in an arsS mutant strain compared to a wild-type strain when the bacteria were cultured at pH 5.0 and also when they were cultured at pH 7.0. Genes encoding 14 of these proteins were directly regulated by the ArsRS system, based on observed binding of ArsR to the relevant promoter regions. The ArsRS-regulated proteins identified in this study contribute to acid resistance (urease and amidase), acetone metabolism (acetone carboxylase), resistance to oxidative stress (thioredoxin reductase), quorum sensing (Pfs), and several other functions. These results provide further definition of the ArsRS regulon and underscore the importance of the ArsRS system in regulating expression of H. pylori proteins during bacterial growth at both neutral pH and acidic pH.
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27
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Gotoh Y, Eguchi Y, Watanabe T, Okamoto S, Doi A, Utsumi R. Two-component signal transduction as potential drug targets in pathogenic bacteria. Curr Opin Microbiol 2010; 13:232-9. [PMID: 20138000 DOI: 10.1016/j.mib.2010.01.008] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 01/12/2010] [Accepted: 01/12/2010] [Indexed: 11/16/2022]
Abstract
Gene clusters contributing to processes such as cell growth and pathogenicity are often controlled by two-component signal transduction systems (TCSs). Specific inhibitors against TCS systems work differently from conventional antibiotics, and developing them into new drugs that are effective against various drug-resistant bacteria may be possible. Furthermore, inhibitors of TCSs that control virulence factors may reduce virulence without killing the pathogenic bacteria. Previous TCS inhibitors targeting the kinase domain of the histidine kinase sensor suffered from poor selectivity. Recent TCS inhibitors, however, target the sensory domains of the sensors blocking the quorum sensing system, or target the essential response regulator. These new targets are introduced, together with several specific TCSs that have the potential to serve as effective drug targets.
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Affiliation(s)
- Yasuhiro Gotoh
- Department of Bioscience, Graduate School of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan
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28
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Duckworth MJ, Okoli AS, Mendz GL. Novel Helicobacter pylori therapeutic targets: the unusual suspects. Expert Rev Anti Infect Ther 2009; 7:835-67. [PMID: 19735225 DOI: 10.1586/eri.09.61] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Understanding the current status of the discovery and development of anti-Helicobacter therapies requires an overview of the searches for therapeutic targets performed to date. A summary is given of the very substantial body of work conducted in the quest to find Helicobacter pylori genes that could be suitable candidates for therapeutic intervention. The products of most of these genes perform metabolic functions, and others have roles in growth, cell motility and colonization. The genes identified as potential targets have been organized into three categories according to their degree of characterization. A short description and evaluation is provided of the main candidates in each category. Investigations of potential therapeutic targets have generated a wealth of information about the physiology and genetics of H. pylori, and its interactions with the host, but have yielded little by way of new therapies.
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Affiliation(s)
- Megan J Duckworth
- School of Medicine, Sydney, The University of Notre Dame Australia, 160 Oxford Street, Darlinghurst, NSW 2010, Australia.
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29
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Abstract
The bacterium Helicobacter pylori is remarkable for its ability to persist in the human stomach for decades without provoking sterilizing immunity. Since repetitive DNA can facilitate adaptive genomic flexibility via increased recombination, insertion, and deletion, we searched the genomes of two H. pylori strains for nucleotide repeats. We discovered a family of genes with extensive repetitive DNA that we have termed the H. pylori RD gene family. Each gene of this family is composed of a conserved 3' region, a variable mid-region encoding 7 and 11 amino acid repeats, and a 5' region containing one of two possible alleles. Analysis of five complete genome sequences and PCR genotyping of 42 H. pylori strains revealed extensive variation between strains in the number, location, and arrangement of RD genes. Furthermore, examination of multiple strains isolated from a single subject's stomach revealed intrahost variation in repeat number and composition. Despite prior evidence that the protein products of this gene family are expressed at the bacterial cell surface, enzyme-linked immunosorbent assay and immunoblot studies revealed no consistent seroreactivity to a recombinant RD protein by H. pylori-positive hosts. The pattern of repeats uncovered in the RD gene family appears to reflect slipped-strand mispairing or domain duplication, allowing for redundancy and subsequent diversity in genotype and phenotype. This novel family of hypervariable genes with conserved, repetitive, and allelic domains may represent an important locus for understanding H. pylori persistence in its natural host.
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30
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Han YH, Liu WZ, Shi YZ, Lu LQ, Xiao SD, Zhang QH. Gene expression profile of Helicobacter pylori in response to growth temperature variation. J Microbiol 2009; 47:455-65. [PMID: 19763420 DOI: 10.1007/s12275-009-0003-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2008] [Accepted: 04/03/2009] [Indexed: 02/07/2023]
Abstract
A Helicobacter pylori whole-genome DNA microarray was constructed to study expression profiles of H. pylori in response to a sudden temperature transfer from 37 degrees C to 20 degrees C. The expression level of the genome at each of four time points (15, 30, 60, and 120 min) after temperature downshift was compared with that just before cold treatment. Globally, 10.2 % (n=167) of the total predicted H. pylori genes (n=1636) represented on the microarray were significantly differentially expressed (p<0.05) over a 120 min period after shift to low temperature. The expression profiles of the differentially expressed genes were grouped, and their expression patterns were validated by quantitative real-time PCR. Up-regulated genes mainly included genes involved in energy metabolism and substance metabolism, cellular processes, protein fate, ribosomal protein genes, and hypothetical protein genes, which indicate the compensational responses of H. pylori to temperature downshift. Those genes play important roles in adaption to temperature downshift of H. pylori. Down-regulation of DNA metabolism genes and cell envelope genes and cellular processes genes may reflect damaged functions under low temperature, which is unfavorable to bacterial infection and propagation. Overall, this time-course study provides new insights into the primary response of H. pylori to a sudden temperature downshift, which allow the bacteria to survive and adapt to the new host environment.
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Affiliation(s)
- Yue-hua Han
- Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, P. R. China.
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31
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Müller S, Götz M, Beier D. Histidine residue 94 is involved in pH sensing by histidine kinase ArsS of Helicobacter pylori. PLoS One 2009; 4:e6930. [PMID: 19759826 PMCID: PMC2736386 DOI: 10.1371/journal.pone.0006930] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 08/12/2009] [Indexed: 11/28/2022] Open
Abstract
Background The ArsRS two-component system is the master regulator of acid adaptation in the human gastric pathogen Helicobacter pylori. Low pH is supposed to trigger the autophosphorylation of the histidine kinase ArsS and the subsequent transfer of the phosphoryl group to its cognate response regulator ArsR which then acts as an activator or repressor of pH-responsive genes. Orthologs of the ArsRS two-component system are also present in H. pylori's close relatives H. hepaticus, Campylobacter jejuni and Wolinella succinogenes which are non-gastric colonizers. Methodology/Principal Findings In order to investigate the mechanism of acid perception by ArsS, derivatives of H. pylori 26695 expressing ArsS proteins with substitutions of the histidine residues present in its periplasmic input domain were constructed. Analysis of pH-responsive transcription of selected ArsRS target genes in these mutants revealed that H94 is relevant for pH sensing, however, our data indicate that protonatable amino acids other than histidine contribute substantially to acid perception by ArsS. By the construction and analysis of H. pylori mutants carrying arsS allels from the related ε-proteobacteria we demonstrate that WS1818 of W. succinogenes efficiently responds to acidic pH. Conclusions/Significance We show that H94 in the input domain of ArsS is crucial for acid perception in H. pylori 26695. In addition our data suggest that ArsS is able to adopt different conformations depending on the degree of protonation of acidic amino acids in the input domain. This might result in different activation states of the histidine kinase allowing a gradual transcriptional response to low pH conditions. Although retaining considerable similarity to ArsS the orthologous proteins of H. hepaticus and C. jejuni may have evolved to sensors of a different environmental stimulus in accordance with the non gastric habitat of these bacteria.
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Affiliation(s)
- Stefanie Müller
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Monika Götz
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Dagmar Beier
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, Würzburg, Germany
- * E-mail:
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32
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Expression of Kingella kingae type IV pili is regulated by sigma54, PilS, and PilR. J Bacteriol 2009; 191:4976-86. [PMID: 19465661 DOI: 10.1128/jb.00123-09] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kingella kingae is a member of the Neisseriaceae and is being recognized increasingly as an important cause of serious disease in children. Recent work has demonstrated that K. kingae expresses type IV pili that mediate adherence to respiratory epithelial and synovial cells and are selected against during invasive disease. In the current study, we examined the genome of K. kingae strain 269-492 and identified homologs of the rpoN and the pilS and pilR genes that are essential for pilus expression in Pseudomonas aeruginosa but not in the pathogenic Neisseria species. The disruption of either rpoN or pilR in K. kingae resulted in a marked reduction in the level of transcript for the major pilus subunit (pilA1) and eliminated piliation. In contrast, the disruption of pilS resulted in only partial reduction in the level of pilA1 transcript and a partial decrease in piliation. Furthermore, the disruption of pilS in colony variants with high-density piliation resulted in variants with low-density piliation. Mutations in the promoter region of pilA1 and gel shift analysis demonstrated that both sigma(54) and PilR act directly at the pilA1 promoter, with PilR binding to two repetitive elements. These data suggest that the regulation of K. kingae type IV pilus expression is complex and multilayered, influenced by both the genetic state and environmental cues.
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33
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Differences in genome content among Helicobacter pylori isolates from patients with gastritis, duodenal ulcer, or gastric cancer reveal novel disease-associated genes. Infect Immun 2009; 77:2201-11. [PMID: 19237517 DOI: 10.1128/iai.01284-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Helicobacter pylori establishes a chronic infection in the human stomach, causing gastritis, peptic ulcer, or gastric cancer, and more severe diseases are associated with virulence genes such as the cag pathogenicity island (PAI). The aim of this work was to study gene content differences among H. pylori strains isolated from patients with different gastroduodenal diseases in a Mexican-Mestizo patient population. H. pylori isolates from 10 patients with nonatrophic gastritis, 10 patients with duodenal ulcer, and 9 patients with gastric cancer were studied. Multiple isolates from the same patient were analyzed by randomly amplified polymorphic DNA analysis, and strains with unique patterns were tested using whole-genome microarray-based comparative genomic hybridization (aCGH). We studied 42 isolates and found 1,319 genes present in all isolates, while 341 (20.5%) were variable genes. Among the variable genes, 127 (37%) were distributed within plasticity zones (PZs). The overall number of variable genes present in a given isolate was significantly lower for gastric cancer isolates. Thirty genes were significantly associated with nonatrophic gastritis, duodenal ulcer, or gastric cancer, 14 (46.6%) of which were within PZs and the cag PAI. Two genes (HP0674 and JHP0940) were absent in all gastric cancer isolates. Many of the disease-associated genes outside the PZs formed clusters, and some of these genes are regulated in response to acid or other environmental conditions. Validation of candidate genes identified by aCGH in a second patient cohort allowed the identification of novel H. pylori genes associated with gastric cancer or duodenal ulcer. These disease-associated genes may serve as biomarkers of the risk for severe gastroduodenal diseases.
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34
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Gupta SS, Borin BN, Cover TL, Krezel AM. Structural analysis of the DNA-binding domain of the Helicobacter pylori response regulator ArsR. J Biol Chem 2008; 284:6536-45. [PMID: 19117956 DOI: 10.1074/jbc.m804592200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The Helicobacter pylori ArsS-ArsR two-component signal transduction system, comprised of a sensor histidine kinase (ArsS) and a response regulator (ArsR), allows the bacteria to regulate gene expression in response to acidic pH. We expressed and purified the full-length ArsR protein and the DNA-binding domain of ArsR (ArsR-DBD), and we analyzed the tertiary structure of the ArsR-DBD using solution nuclear magnetic resonance (NMR) methods. Both the full-length ArsR and the ArsR-DBD behaved as monomers in size exclusion chromatography experiments. The structure of ArsR-DBD consists of an N-terminal four-stranded beta-sheet, a helical core, and a C-terminal beta-hairpin. The overall tertiary fold of the ArsR-DBD is most closely related to DBD structures of the OmpR/PhoB subfamily of bacterial response regulators. However, the orientation of the N-terminal beta-sheet with respect to the rest of the DNA-binding domain is substantially different in ArsR compared with the orientation in related response regulators. Molecular modeling of an ArsR-DBD-DNA complex permits identification of protein elements that are predicted to bind target DNA sequences and thereby regulate gene transcription in H. pylori.
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Affiliation(s)
- Shobhana S Gupta
- Department of Microbiology and Immunology, Vanderbilt University and Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232, USA
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35
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Goodwin AC, Weinberger DM, Ford CB, Nelson JC, Snider JD, Hall JD, Paules CI, Peek RM, Forsyth MH. Expression of the Helicobacter pylori adhesin SabA is controlled via phase variation and the ArsRS signal transduction system. MICROBIOLOGY-SGM 2008; 154:2231-2240. [PMID: 18667556 PMCID: PMC2715451 DOI: 10.1099/mic.0.2007/016055-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Adaptation to the acidic microenvironment, and adherence to mucosal epithelium, are essential for persistent colonization of the human stomach by Helicobacter pylori. The expression of SabA, an adhesin implicated in the ability of H. pylori to adhere to the host gastric epithelium, can be modulated by phase variation via slipped-strand mispairing in repetitive nucleotide tracts located in both the promoter region and the coding region. This study demonstrates the occurrence of phase variation at the sabA locus within individual strains of H. pylori, and among multiple isolates from a single patient. In addition, transcription of sabA is repressed by the acid-responsive ArsRS two-component signal transduction system in vitro. Our results demonstrate that isogenic inactivation of the arsS (jhp0151/HP0165) histidine kinase locus results in a 10-fold SabA-dependent increase in adherence to gastric epithelial cells in strain J99 (contains an in-frame sabA allele), but not in strain 26695 (out-of-frame sabA allele). The combination of transcriptional regulation of the sabA locus by the ArsRS two-component signal-transduction system and the generation of subpopulations harbouring alternate sabA alleles by slipped-strand mispairing during chromosomal replication could permit H. pylori to rapidly adapt to varying microenvironments or host immune responses. As a pathogen with a paucity of regulatory proteins, this dual regulation indicates that SabA expression is a tightly regulated process in H. pylori infection.
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Affiliation(s)
- Andrew C Goodwin
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Daniel M Weinberger
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Christopher B Ford
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Jessica C Nelson
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Jonathan D Snider
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Joshua D Hall
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Catharine I Paules
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
| | - Richard M Peek
- Department of Veterans Affairs Medical Center, Nashville, TN 37212, USA.,Division of Gastroenterology and Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-2279, USA
| | - Mark H Forsyth
- Department of Biology, The College of William and Mary, Williamsburg, VA 23187-8795, USA
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Abstract
Porphyromonas gingivalis is a Gram-negative oral anaerobe associated with chronic adult periodontitis. Its ecological niche is the gingival crevice, where the organism adapts to the challenges of the infectious process such as host defence and bacterial products. Bacterial responses to environmental changes are partly regulated by two-component signal transduction systems. Several intact systems were annotated in the genome of P. gingivalis, as well as an orphan regulator encoding a homologue of RprY, a response regulator from Bacteroides fragilis. With the goal of defining the environmental cues that activate RprY in P. gingivalis, we used several strategies to identify its regulon. Results from gene expression and DNA-protein binding assays identified target genes that were either involved in transport functions or associated with oxidative stress, and indicated that RprY can act as an activator and a repressor. RprY positively activated the primary sodium pump, NADH : ubiquinone oxidoreductase (NQR), and RprY protein also interacted with the promoter regions of nqrA genes from B. fragilis and Vibrio cholerae. Given that gingival bleeding and infiltration of host defence cells are symptoms of periodontal infection, iron products released from blood and reactive oxygen species from polymorphonuclear leucocytes may be potential inducers of the RprY regulon.
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Affiliation(s)
- Ana E Duran-Pinedo
- Department of Molecular Genetics, Forsyth Institute, Boston, MA 02115, USA
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37
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de Reuse H, Bereswill S. Ten years after the first Helicobacter pylori genome: comparative and functional genomics provide new insights in the variability and adaptability of a persistent pathogen. ACTA ACUST UNITED AC 2007; 50:165-76. [PMID: 17567280 DOI: 10.1111/j.1574-695x.2007.00244.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In this review, we summarize how genomic approaches contributed to the understanding of the biology of the recently discovered pathogen Helicobacter pylori. Comparative genomics provided new insights into H. pylori's spectacular genetic diversity and generated exiting hypotheses on its evolutionary history. Transcriptomic studies provided original information on the mechanisms of H. pylori gastric adaptation that are central to its virulence.
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Affiliation(s)
- Hilde de Reuse
- Institut Pasteur, Unité de Pathogénie Bacterienne des Muqueuses, Paris, France
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Josenhans C, Beier D, Linz B, Meyer TF, Suerbaum S. Pathogenomics of helicobacter. Int J Med Microbiol 2007; 297:589-600. [PMID: 17416549 DOI: 10.1016/j.ijmm.2007.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 02/05/2007] [Accepted: 02/05/2007] [Indexed: 02/07/2023] Open
Abstract
The pathogenic bacterium Helicobacter pylori infects half of the human population and is one of the genetically most diverse bacterial species known. H. pylori was one of the first bacterial species whose genome was sequenced in 1997, and the first species for which two complete sequences from independent isolates were available for within-species comparisons. For almost 10 years, genomic and post-genomic analysis has contributed enormously to our understanding of the pathogenesis of H. pylori infection. This review summarizes the available information, emphasizing work performed in the framework of the PathoGenoMik funding initiative (2001-2006) of the German Ministry of Education and Research.
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Affiliation(s)
- Christine Josenhans
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Carl-Neuberg-Street 1, D-30625 Hannover, Germany
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Pflock M, Kennard S, Finsterer N, Beier D. Acid-responsive gene regulation in the human pathogen Helicobacter pylori. J Biotechnol 2006; 126:52-60. [PMID: 16713649 DOI: 10.1016/j.jbiotec.2006.03.045] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 02/02/2006] [Accepted: 03/30/2006] [Indexed: 01/03/2023]
Abstract
Helicobacter pylori is a human gastric pathogen which is extremely well adapted to the low pH environment of the stomach, since it has evolved mechanisms to survive both severe acid shocks and to grow under mildly acidic conditions. Central to the acid resistance of H. pylori is the enzyme urease whose function is to maintain the cytoplasmic and periplasmic pH of the bacterium near neutrality. Substantial progress has been made recently in unravelling the complex regulation of urease expression and the expression of additional genes involved in the acid adaptation of H. pylori. Acid-responsive gene regulation involves the two-component system ArsRS and the metal responsive pleiotropic transcriptional regulators NikR and Fur which control partially overlapping regulons. Here we review our current understanding of the mechanisms of transcriptional regulation governing the acid response of H. pylori.
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Affiliation(s)
- Michael Pflock
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Pflock M, Finsterer N, Joseph B, Mollenkopf H, Meyer TF, Beier D. Characterization of the ArsRS regulon of Helicobacter pylori, involved in acid adaptation. J Bacteriol 2006; 188:3449-62. [PMID: 16672598 PMCID: PMC1482845 DOI: 10.1128/jb.188.10.3449-3462.2006] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The human gastric pathogen Helicobacter pylori is extremely well adapted to the highly acidic conditions encountered in the stomach. The pronounced acid resistance of H. pylori relies mainly on the ammonia-producing enzyme urease; however, urease-independent mechanisms are likely to contribute to acid adaptation. Acid-responsive gene regulation is mediated at least in part by the ArsRS two-component system consisting of the essential OmpR-like response regulator ArsR and the nonessential cognate histidine kinase ArsS, whose autophosphorylation is triggered in response to low pH. In this study, by global transcriptional profiling of an ArsS-deficient H. pylori mutant grown at pH 5.0, we define the ArsR approximately P-dependent regulon consisting of 109 genes, including the urease gene cluster, the genes encoding the aliphatic amidases AmiE and AmiF, and the rocF gene encoding arginase. We show that ArsR approximately P controls the acid-induced transcription of amiE and amiF by binding to extended regions located upstream of the -10 box of the respective promoters. In contrast, transcription of rocF is repressed by ArsR approximately P at neutral, acidic, and mildly alkaline pH via high-affinity binding of the response regulator to a site overlapping the promoter of the rocF gene.
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Affiliation(s)
- Michael Pflock
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, Germany
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41
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Loh JT, Cover TL. Requirement of histidine kinases HP0165 and HP1364 for acid resistance in Helicobacter pylori. Infect Immun 2006; 74:3052-9. [PMID: 16622250 PMCID: PMC1459715 DOI: 10.1128/iai.74.5.3052-3059.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, we investigated a potential requirement of two-component signal transduction systems for acid resistance in Helicobacter pylori. In comparison to a wild-type strain, isogenic strains with null mutations in either HP0165 or HP1364 histidine kinases were impaired in their ability to grow at pH 5.0. The growth of complemented mutant strains was similar to that of the wild-type strain. H. pylori DNA array analyses and transcriptional reporter assays indicated that acid-responsive gene transcription was altered in the HP0165 and HP1364 null mutant strains compared to the parental wild-type strain. These results indicate that intact HP0165 and HP1364 histidine kinases are required for acid resistance in H. pylori.
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Affiliation(s)
- John T Loh
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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42
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Wen Y, Feng J, Scott DR, Marcus EA, Sachs G. Involvement of the HP0165-HP0166 two-component system in expression of some acidic-pH-upregulated genes of Helicobacter pylori. J Bacteriol 2006; 188:1750-61. [PMID: 16484186 PMCID: PMC1426556 DOI: 10.1128/jb.188.5.1750-1761.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
About 200 genes of the gastric pathogen Helicobacter pylori increase expression at medium pHs of 6.2, 5.5, and 4.5, an increase that is abolished or much reduced by the buffering action of urease. Genes up-regulated by a low pH include the two-component system HP0165-HP0166, suggesting a role in the regulation of some of the pH-sensitive genes. To identify targets of HP0165-HP0166, the promoter regions of genes up-regulated by a low pH were grouped based on sequence similarity. Probes for promoter sequences representing each group were subjected to electrophoretic mobility shift assays (EMSA) with recombinant HP0166-His(6) or a mutated response regulator, HP0166-D52N-His(6), that can specifically determine the role of phosphorylation of HP0166 in binding (including a control EMSA with in-vitro-phosphorylated HP0166-His(6)). Nineteen of 45 promoter-regulatory regions were found to interact with HP0166-His(6). Seven promoters for genes encoding alpha-carbonic anhydrase, omp11, fecD, lpp20, hypA, and two with unknown function (pHP1397-1396 and pHP0654-0675) were clustered in gene group A, which may respond to changes in the periplasmic pH at a constant cytoplasmic pH and showed phosphorylation-dependent binding in EMSA with HP0166-D52N-His(6). Twelve promoters were clustered in groups B and C whose up-regulation likely also depends on a reduction of the cytoplasmic pH at a medium pH of 5.5 or 4.5. Most of the target promoters in groups B and C showed phosphorylation-dependent binding with HP0166-D52N-His(6), but promoters for ompR (pHP0166-0162), pHP0682-0681, and pHP1288-1289 showed phosphorylation-independent binding. These findings, combined with DNase I footprinting, suggest that HP0165-0166 is an acid-responsive signaling system affecting the expression of pH-sensitive genes. Regulation of these genes responds either to a decrease in the periplasmic pH alone (HP0165 dependent) or also to a decrease in the cytoplasmic pH (HP0165 independent).
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Affiliation(s)
- Yi Wen
- Membrane Biology Laboratory, Department of Physiology, David Geffen School of Medicine at UCLA, VA Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA.
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43
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Pflock M, Kennard S, Delany I, Scarlato V, Beier D. Acid-induced activation of the urease promoters is mediated directly by the ArsRS two-component system of Helicobacter pylori. Infect Immun 2005; 73:6437-45. [PMID: 16177315 PMCID: PMC1230922 DOI: 10.1128/iai.73.10.6437-6445.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The nickel-containing enzyme urease is an essential colonization factor of the human gastric pathogen Helicobacter pylori which enables the bacteria to survive the low-pH conditions of the stomach. Transcription of the urease genes is positively controlled in response to increasing concentrations of nickel ions and acidic pH. Here we demonstrate that acid-induced transcription of the urease genes is mediated directly by the ArsRS two-component system. Footprint analyses identify binding sites of the phosphorylated ArsR response regulator within the ureA and ureI promoters. Furthermore, deletion of a distal upstream ArsR binding site of the ureA promoter demonstrates its role in acid-dependent activation of the promoter. In addition, acid-induced transcription of the ureA gene is unaltered in a nikR mutant, providing evidence that pH-responsive regulation and nickel-responsive regulation of the ureA promoter are mediated by independent mechanisms involving the ArsR response regulator and the NikR protein.
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Affiliation(s)
- Michael Pflock
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Germany
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44
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Wei JR, Tsai YH, Soo PC, Horng YT, Hsieh SC, Ho SW, Lai HC. Biochemical characterization of RssA-RssB, a two-component signal transduction system regulating swarming behavior in Serratia marcescens. J Bacteriol 2005; 187:5683-90. [PMID: 16077114 PMCID: PMC1196059 DOI: 10.1128/jb.187.16.5683-5690.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Our previous study had identified a pair of potential two-component signal transduction proteins, RssA-RssB, involved in the regulation of Serratia marcescens swarming. When mutated, both rssA and rssB mutants showed precocious swarming phenotypes on LB swarming agar, whereby swarming not only occurred at 37 degrees C but also initiated on a surface of higher agar concentration and more rapidly than did the parent strain at 30 degrees C. In this study, we further show that the predicted sensor kinase RssA and the response regulator RssB bear characteristics of components of the phosphorelay signaling system. In vitro phosphorylation and site-directed mutagenesis assays showed that phosphorylated RssA transfers the phosphate group to RssB and that histidine 248 and aspartate 51 are essential amino acid residues involved in the phosphotransfer reactions in RssA and RssB, respectively. Accordingly, while wild-type rssA could, the mutated rssA(H248A) in trans could not complement the precocious swarming phenotype of the rssA mutant. Although RssA-RssB regulates expressions of shlA and ygfF of S. marcescens (ygfF(Sm)), in vitro DNA-binding assays showed that the phosphorylated RssB did not bind directly to the promoter regions of these two genes but bound to its own rssB promoter. Subsequent assays located the RssB binding site within a 63-bp rssB promoter DNA region and confirmed a direct negative autoregulation of the RssA-RssB signaling pathway. These results suggest that when activated, RssA-RssB acts as a negative regulator for controlling the initiation of S. marcescens swarming.
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Affiliation(s)
- Jun-Rong Wei
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, No. 1. Chang-Der Street, Taipei 100, Taiwan, Republic of China
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45
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Müller S, Förster J, Beier D. Repeated sequence motifs in the Helicobacter pylori P1408 promoter do not affect its transcription. Microbiol Res 2005; 161:212-21. [PMID: 16765837 DOI: 10.1016/j.micres.2005.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2005] [Indexed: 11/20/2022]
Abstract
The ArsRS two-component system controls the pH-dependent transcription of several target genes involved in the acid resistance of Helicobacter pylori. In its phosphorylated form the response regulator ArsR activates transcription of the urease genes and it has been reported that ArsR approximately P binds to a 26 bp consensus motif which is present in the promoter regions of the ORFs hp1408, hp119 and hp1432 encoding proteins of unknown function. Here we show that the upstream region of ORF hp1408 exhibits considerable sequence variation in different isolates of H. pylori. By the construction of fusions of the P(1408) promoter from different H. pylori strains to the reporter gene gfp in the genetic background of H. pylori G27 we demonstrate that these sequence variations do not significantly affect acid-induced transcription. Furthermore, we show that a P(1408) core promoter comprising only the -10 promoter element and the 26 bp ArsR binding site overlapping the -35 region is sufficient for eliciting the normal acid response of ORF hp1408.
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Affiliation(s)
- Stefanie Müller
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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46
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Waidner B, Melchers K, Stähler FN, Kist M, Bereswill S. The Helicobacter pylori CrdRS two-component regulation system (HP1364/HP1365) is required for copper-mediated induction of the copper resistance determinant CrdA. J Bacteriol 2005; 187:4683-8. [PMID: 15968080 PMCID: PMC1151771 DOI: 10.1128/jb.187.13.4683-4688.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here we describe that the Helicobacter pylori sensor kinase produced by HP1364 and the response regulator produced by HP1365 and designated CrdS and CrdR, respectively, are both required for transcriptional induction of the H. pylori copper resistance determinant CrdA by copper ions. CrdRS-deficient mutants lacked copper induction of crdA expression and were copper sensitive. A direct role of CrdR in transcriptional regulation of crdA was confirmed by in vitro binding of CrdR to the crdA upstream region. A 21-nucleotide sequence located near the crdA promoter was shown to be required for CrdR binding.
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Affiliation(s)
- Barbara Waidner
- Department of Medical Microbiology and Hygiene, Institute of Medical Microbiology and Hygiene, University Hospital Freiburg, Hermann-Herder-Strasse 11, D-79104 Freiburg, Germany.
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47
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Schär J, Sickmann A, Beier D. Phosphorylation-independent activity of atypical response regulators of Helicobacter pylori. J Bacteriol 2005; 187:3100-9. [PMID: 15838037 PMCID: PMC1082831 DOI: 10.1128/jb.187.9.3100-3109.2005] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of the gastric pathogen Helicobacter pylori harbors a remarkably low number of regulatory genes, including three and five open reading frames encoding two-component histidine kinases and response regulators, respectively, which are putatively involved in transcriptional regulation. Two of the response regulator genes, hp1043 and hp166, proved to be essential for cell growth, and inactivation of the response regulator gene hp1021 resulted in a severe growth defect, as indicated by a small-colony phenotype. The sequences of the receiver domains of response regulators HP1043 and HP1021 differ from the consensus sequence of the acidic pocket of the receiver domain which is involved in the phosphotransfer reaction from the histidine kinase to the response regulator. Using a genetic complementation system, we demonstrated that the function of response regulator HP166, which is essential for cell growth, can be provided by a mutated derivative carrying a D52N substitution at the site of phosphorylation. We found that the atypical receiver sequences of HP1043 and HP1021 are not crucial for the function of these response regulators. Phosphorylation of the receiver domains of HP1043 and HP1021 is not needed for response regulator function and may not occur at all. Thus, the phosphorylation-independent action of these regulators differs from the well-established two-component paradigm.
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Affiliation(s)
- Jennifer Schär
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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48
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Mohedano ML, Overweg K, de la Fuente A, Reuter M, Altabe S, Mulholland F, de Mendoza D, López P, Wells JM. Evidence that the essential response regulator YycF in Streptococcus pneumoniae modulates expression of fatty acid biosynthesis genes and alters membrane composition. J Bacteriol 2005; 187:2357-67. [PMID: 15774879 PMCID: PMC1065234 DOI: 10.1128/jb.187.7.2357-2367.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The YycFG two-component system, originally identified in Bacillus subtilis, is highly conserved among gram-positive bacteria with low G+C contents. In Streptococcus pneumoniae, the YycF response regulator has been reported to be essential for cell growth, but the signal to which it responds and the gene members of the regulon remain unclear. In order to investigate the role of YycFG in S. pneumoniae, we increased the expression of yycF by using a maltose-inducible vector and analyzed the genome-wide effects on transcription and protein expression during the course of yycF expression. The induction of yycF expression increased histidine kinase yycG transcript levels, suggesting an autoregulation of the yycFG operon. Evidence from both proteomic and microarray transcriptome studies as well as analyses of membrane fatty acid composition indicated that YycFG is involved in the regulation of fatty acid biosynthesis pathways and in determining fatty acid chain lengths in membrane lipids. In agreement with recent transcriptome data on pneumococcal cells depleted of YycFG, we also identified several other potential members of the YycFG regulon that are required for virulence and cell wall biosynthesis and metabolism.
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Affiliation(s)
- M Luz Mohedano
- Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040 Madrid, Spain
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49
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Nishikawa K, Yoshimura F, Duncan MJ. A regulation cascade controls expression of Porphyromonas gingivalis fimbriae via the FimR response regulator. Mol Microbiol 2005; 54:546-60. [PMID: 15469523 DOI: 10.1111/j.1365-2958.2004.04291.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Little is known about how Porphyromonas gingivalis, a Gram-negative oral anaerobe, senses environmental changes, and how such information is transmitted to the cell. The production of P. gingivalis surface fimbriae is regulated by FimS-FimR, a two component signal transduction system. Expression of fimA, encoding the fimbrilin protein subunit of fimbriae, is positively regulated by the FimR response regulator. In this study we investigated the molecular mechanisms of FimR regulation of fimA expression. Comparative transcription profiling of fimR wild-type and mutant strains shows that FimR controls the expression of several genes including five clustered around the fimA locus. Chromatin immunoprecipitation assays and electrophoretic mobility shift assays identify and confirm that FimR binds to the promoter region of the first gene in the fimA cluster. Gene expression analyses of mutant strains reveal a transcriptional cascade involving multiple steps, with FimR activating expression of the first gene of the cluster that encodes a key regulatory protein.
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Affiliation(s)
- Kiyoshi Nishikawa
- Department of Molecular Genetics, The Forsyth Institute, Boston, MA 02115, USA
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50
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McNulty SL, Mole BM, Dailidiene D, Segal I, Ally R, Mistry R, Secka O, Adegbola RA, Thomas JE, Lenarcic EM, Peek RM, Berg DE, Forsyth MH. Novel 180- and 480-base-pair insertions in African and African-American strains of Helicobacter pylori. J Clin Microbiol 2005; 42:5658-63. [PMID: 15583296 PMCID: PMC535299 DOI: 10.1128/jcm.42.12.5658-5663.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Helicobacter pylori is a genetically diverse bacterial species that chronically infects human stomachs and sometimes causes severe gastroduodenal disease. Studies of polymorphic DNA sequences can suggest geographic origins of individual strains. Here, we describe a 180-bp insertion (ins180), which is just after the translation stop of a gene of unknown function, near the promoter of jhp0152-jhp0151 two-component signal transduction genes in strain J99, and absent from this site in strain 26695. This ins180 insertion was found in 9 of 9 Gambian (West African), 9 of 20 (45%) South African, and 9 of 40 (23%) Spanish strains but in only 2 of 20 (10%) North American strains and none of 20 Lithuanian, 20 Indian, and 20 Japanese strains. Four South African isolates that lacked ins180 and that belonged to an unusual outlier group contained a 480-bp insertion at this site (ins480), whereas none of 181 other strains screened contained ins480. In further tests 56% (10 of 18) of strains from African Americans but only 17% (3 of 18) of strains from Caucasian Americans carried ins180 (P < 0.05). Thus, the H. pylori strains of modern African Americans seem to retain traces of African roots, despite the multiple generations since their ancestors were taken from West Africa. Fragmentary ins180-like sequences were found at numerous sites in H. pylori genomes, always between genes. Such sequences might affect regulation of transcription and could facilitate genome rearrangement by homologous recombination. Apparent differences between African-American and Caucasian-American H. pylori gene pools may bear on our understanding of H. pylori transmission and disease outcome.
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Affiliation(s)
- Shannon L McNulty
- Department of Biology, The College of William and Mary, 214 Millington Hall, Landrum Drive, Williamsburg, VA 23187, USA
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