1
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Xiao L, Liu G, Gong F, Zhu H, Zhang Y, Cai Z, Li Y. A Minimized Synthetic Carbon Fixation Cycle. ACS Catal 2021. [DOI: 10.1021/acscatal.1c04151] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Lu Xiao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guoxia Liu
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Fuyu Gong
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huawei Zhu
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanping Zhang
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhen Cai
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yin Li
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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2
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Yao X, Xiao S, Zhou L. Integrative proteomic and metabolomic analyses reveal the mechanism by which bismuth enables Helicobacter pylori eradication. Helicobacter 2021; 26:e12846. [PMID: 34414638 DOI: 10.1111/hel.12846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 01/08/2023]
Abstract
BACKGROUND Bismuth-based drugs are used to treat Helicobacter pylori infection; however, the antibacterial activity of bismuth, especially against H. pylori, has not been fully elucidated. In this study, the mechanisms by which bismuth exerts its detrimental effects on H. pylori were evaluated. Methods Six H. pylori strains isolated from different patients were cultured with or without bismuth; proteins and metabolites differentially expressed in these two sets of bacteria were detected via data independent acquisition proteomic and gas chromatography-mass spectrometry metabolic approaches, respectively. Gene ontology functional analysis and Kyoto Encyclopedia of Genes and Genomes database were used to identity pathway enrichment. RESULTS Bismuth inhibited H. pylori growth in vitro via the following mechanisms: downregulation of virulence proteins CagA and VacA; disruption of flagella assembly responsible for bacterial colonization; and inhibition of antioxidant enzymes, including catalase, catalase-related peroxidase, and superoxide dismutase. Diverse metabolic pathways related to growth and RNA translation in H. pylori were disrupted by bismuth. Bismuth treatment impaired many biological processes in H. pylori, including antioxidant response and purine, pyrimidine, amino acid, and carbon metabolism. Conclusions The findings of this study suggest that motility, virulence factors CagA and VacA, antioxidant defense system, and many important metabolic pathways associated with bacterial growth, including nucleotide and amino acid metabolism and translation in H. pylori, are inhibited by bismuth. This study provides novel insights into the mechanism by which bismuth eradicates H. pylori upon being incorporated into quadruple therapy.
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Affiliation(s)
- Xingyu Yao
- Department of Gastroenterology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Helicobacter pylori Infection and Upper Gastrointestinal Diseases, Peking University Third Hospital, Beijing, China
| | - Shiyu Xiao
- Department of Gastroenterology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Helicobacter pylori Infection and Upper Gastrointestinal Diseases, Peking University Third Hospital, Beijing, China
| | - Liya Zhou
- Department of Gastroenterology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Helicobacter pylori Infection and Upper Gastrointestinal Diseases, Peking University Third Hospital, Beijing, China
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3
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The reductive carboxylation activity of heterotetrameric pyruvate synthases from hyperthermophilic archaea. Biochem Biophys Res Commun 2021; 572:151-156. [PMID: 34364295 DOI: 10.1016/j.bbrc.2021.07.091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 11/20/2022]
Abstract
Pyruvate synthase (pyruvate:ferredoxin oxidoreductase, PFOR) catalyzes the interconversion of acetyl-CoA and pyruvate, but the reductive carboxylation activities of heterotetrameric PFORs remain largely unknown. In this study, we cloned, expressed, and purified selected six heterotetrameric PFORs from hyperthermophilic archaea. The reductive carboxylation activities of these heterotetrameric PFORs were measured at 70 °C and the ratio of reductive carboxylation activity to oxidative decarboxylation activity (red/ox ratio) were calculated. Four out of six showed reductive decarboxylation activities. Among them, the PFORpfm from Pyrolobus fumarii showed the highest reductive carboxylation activities and the highest red/ox ratio, which were 54.32 mU/mg and 0.51, respectively. The divergence of the reductive carboxylation activities and the red/ox ratios of heterotetrameric PFORs in hyperthermophilic archaea indicate the diversity of the functions of PFOR over long-term evolution. This can help us better understand the autotrophic CO2 fixation process in thermal vent, or in other CO2-rich high temperature habitat.
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4
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Steiner TM, Lettl C, Schindele F, Goebel W, Haas R, Fischer W, Eisenreich W. Substrate usage determines carbon flux via the citrate cycle in Helicobacter pylori. Mol Microbiol 2021; 116:841-860. [PMID: 34164854 DOI: 10.1111/mmi.14775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 06/07/2021] [Accepted: 06/19/2021] [Indexed: 12/31/2022]
Abstract
Helicobacter pylori displays a worldwide infection rate of about 50%. The Gram-negative bacterium is the main reason for gastric cancer and other severe diseases. Despite considerable knowledge about the metabolic inventory of H. pylori, carbon fluxes through the citrate cycle (TCA cycle) remained enigmatic. In this study, different 13 C-labeled substrates were supplied as carbon sources to H. pylori during microaerophilic growth in a complex medium. After growth, 13 C-excess and 13 C-distribution were determined in multiple metabolites using GC-MS analysis. [U-13 C6 ]Glucose was efficiently converted into glyceraldehyde but only less into TCA cycle-related metabolites. In contrast, [U-13 C5 ]glutamate, [U-13 C4 ]succinate, and [U-13 C4 ]aspartate were incorporated at high levels into intermediates of the TCA cycle. The comparative analysis of the 13 C-distributions indicated an adaptive TCA cycle fully operating in the closed oxidative direction with rapid equilibrium fluxes between oxaloacetate-succinate and α-ketoglutarate-citrate. 13 C-Profiles of the four-carbon intermediates in the TCA cycle, especially of malate, together with the observation of an isocitrate lyase activity by in vitro assays, suggested carbon fluxes via a glyoxylate bypass. In conjunction with the lack of enzymes for anaplerotic CO2 fixation, the glyoxylate bypass could be relevant to fill up the TCA cycle with carbon atoms derived from acetyl-CoA.
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Affiliation(s)
- Thomas M Steiner
- Bavarian NMR Center-Structural Membrane Biochemistry, Department of Chemistry, Technische Universität München, Garching, Germany
| | - Clara Lettl
- Chair of Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, LMU Munich, München, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, München, Germany
| | - Franziska Schindele
- Chair of Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, LMU Munich, München, Germany
| | - Werner Goebel
- Chair of Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, LMU Munich, München, Germany
| | - Rainer Haas
- Chair of Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, LMU Munich, München, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, München, Germany
| | - Wolfgang Fischer
- Chair of Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, LMU Munich, München, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, München, Germany
| | - Wolfgang Eisenreich
- Bavarian NMR Center-Structural Membrane Biochemistry, Department of Chemistry, Technische Universität München, Garching, Germany
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5
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Flavodoxins as Novel Therapeutic Targets against Helicobacter pylori and Other Gastric Pathogens. Int J Mol Sci 2020; 21:ijms21051881. [PMID: 32164177 PMCID: PMC7084853 DOI: 10.3390/ijms21051881] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 02/06/2023] Open
Abstract
Flavodoxins are small soluble electron transfer proteins widely present in bacteria and absent in vertebrates. Flavodoxins participate in different metabolic pathways and, in some bacteria, they have been shown to be essential proteins representing promising therapeutic targets to fight bacterial infections. Using purified flavodoxin and chemical libraries, leads can be identified that block flavodoxin function and act as bactericidal molecules, as it has been demonstrated for Helicobacter pylori (Hp), the most prevalent human gastric pathogen. Increasing antimicrobial resistance by this bacterium has led current therapies to lose effectiveness, so alternative treatments are urgently required. Here, we summarize, with a focus on flavodoxin, opportunities for pharmacological intervention offered by the potential protein targets described for this bacterium and provide information on other gastrointestinal pathogens and also on bacteria from the gut microbiota that contain flavodoxin. The process of discovery and development of novel antimicrobials specific for Hp flavodoxin that is being carried out in our group is explained, as it can be extrapolated to the discovery of inhibitors specific for other gastric pathogens. The high specificity for Hp of the antimicrobials developed may be of help to reduce damage to the gut microbiota and to slow down the development of resistant Hp mutants.
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6
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Salillas S, Alías M, Michel V, Mahía A, Lucía A, Rodrigues L, Bueno J, Galano-Frutos JJ, De Reuse H, Velázquez-Campoy A, Carrodeguas JA, Sostres C, Castillo J, Aínsa JA, Díaz-de-Villegas MD, Lanas Á, Touati E, Sancho J. Design, Synthesis, and Efficacy Testing of Nitroethylene- and 7-Nitrobenzoxadiazol-Based Flavodoxin Inhibitors against Helicobacter pylori Drug-Resistant Clinical Strains and in Helicobacter pylori-Infected Mice. J Med Chem 2019; 62:6102-6115. [DOI: 10.1021/acs.jmedchem.9b00355] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Sandra Salillas
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | - Miriam Alías
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
| | - Valérie Michel
- Helicobacter Pathogenesis Unit, Department of Microbiology, CNRS ERL6002, Institut Pasteur, 25-28 Rue du Dr. Roux, Paris 75724, France
| | - Alejandro Mahía
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | - Ainhoa Lucía
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | - Liliana Rodrigues
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | | | - Juan José Galano-Frutos
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | - Hilde De Reuse
- Helicobacter Pathogenesis Unit, Department of Microbiology, CNRS ERL6002, Institut Pasteur, 25-28 Rue du Dr. Roux, Paris 75724, France
| | - Adrián Velázquez-Campoy
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
- Fundación ARAID, Gobierno de Aragón, Zaragoza 50009, Spain
| | - José Alberto Carrodeguas
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | - Carlos Sostres
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | | | - José Antonio Aínsa
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | | | - Ángel Lanas
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
| | - Eliette Touati
- Helicobacter Pathogenesis Unit, Department of Microbiology, CNRS ERL6002, Institut Pasteur, 25-28 Rue du Dr. Roux, Paris 75724, France
| | - Javier Sancho
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza 50018, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza 50009, Spain
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7
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Mothersole RG, Macdonald M, Kolesnikov M, Murphy MEP, Wolthers KR. Structural insight into the high reduction potentials observed for Fusobacterium nucleatum flavodoxin. Protein Sci 2019; 28:1460-1472. [PMID: 31116469 DOI: 10.1002/pro.3661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 11/08/2022]
Abstract
Flavodoxins are small flavin mononucleotide (FMN)-containing proteins that mediate a variety of electron transfer processes. The primary sequence of flavodoxin from Fusobacterium nucleatum, a pathogenic oral bacterium, is marked with a number of distinct features including a glycine to lysine (K13) substitution in the highly conserved phosphate-binding loop (T/S-X-T-G-X-T), variation in the aromatic residues that sandwich the FMN cofactor, and a more even distribution of acidic and basic residues. The Eox/sq (oxidized/semiquinone; -43 mV) and Esq/hq (semiquinone/hydroquinone; -256 mV) are the highest recorded reduction potentials of known long-chain flavodoxins. These more electropositive values are a consequence of the apoprotein binding to the FMN hydroquinone anion with ~70-fold greater affinity compared to the oxidized form of the cofactor. Inspection of the FnFld crystal structure revealed the absence of a hydrogen bond between the protein and the oxidized FMN N5 atom, which likely accounts for the more electropositive Eox/sq . The more electropositive Esq/hq is likely attributed to only one negatively charged group positioned within 12 Å of the FMN N1. We show that natural substitutions of highly conserved residues partially account for these more electropositive reduction potentials.
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Affiliation(s)
- Robert G Mothersole
- Department of Chemistry, University at the British Columbia, Kelowna, British Columbia, V1V 1V7, Canada
| | - Marta Macdonald
- Department of Chemistry, University at the British Columbia, Kelowna, British Columbia, V1V 1V7, Canada
| | - Maxim Kolesnikov
- Department of Microbiology and Immunology, University at the British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, University at the British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Kirsten R Wolthers
- Department of Chemistry, University at the British Columbia, Kelowna, British Columbia, V1V 1V7, Canada
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8
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Han B, Zhang Z, Xie Y, Hu X, Wang H, Xia W, Wang Y, Li H, Wang Y, Sun H. Multi-omics and temporal dynamics profiling reveal disruption of central metabolism in Helicobacter pylori on bismuth treatment. Chem Sci 2018; 9:7488-7497. [PMID: 30510674 PMCID: PMC6223348 DOI: 10.1039/c8sc01668b] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 07/23/2018] [Indexed: 12/13/2022] Open
Abstract
Integration of multi-omics enables uncovering cellular responses to stimuli or the mechanism of action of a drug at a system level. Bismuth drugs have long been used for the treatment of Helicobacter pylori infection and their antimicrobial activity was attributed to dysfunction of multiple proteins based on previous proteome-wide studies. Herein, we investigated the response of H. pylori to a bismuth drug at transcriptome and metabolome levels. Our multi-omics data together with bioassays comprehensively reveal the impact of bismuth on a diverse array of intracellular pathways, in particular, disruption of central carbon metabolism is systematically evaluated as a primary bismuth-targeting system in H. pylori. Through temporal dynamics profiling, we demonstrate that bismuth initially perturbs the TCA cycle and then urease activity, followed by the induction of oxidative stress and inhibition of energy production, and in the meantime, induces extensive down-regulation in H. pylori metabolome. The present study thus expands our knowledge on the inhibitory actions of bismuth and provides a novel systematic perspective of H. pylori in response to a clinical drug that sheds light on enhanced therapeutic methodologies.
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Affiliation(s)
- Bingjie Han
- School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China .
| | - Zhen Zhang
- School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China .
| | - Yanxuan Xie
- School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China .
| | - Xuqiao Hu
- Department of Chemistry , The University of Hong Kong , Hong Kong , P. R. China .
| | - Haibo Wang
- Department of Chemistry , The University of Hong Kong , Hong Kong , P. R. China .
| | - Wei Xia
- School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China .
| | - Yulan Wang
- CAS Key Laboratory of Magnetic Resonance in Biological Systems , State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics , Wuhan Institute of Physics and Mathematics , Chinese Academy of Sciences , Wuhan , 430071 , P. R. China
| | - Hongyan Li
- Department of Chemistry , The University of Hong Kong , Hong Kong , P. R. China .
| | - Yuchuan Wang
- School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China .
| | - Hongzhe Sun
- School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China .
- Department of Chemistry , The University of Hong Kong , Hong Kong , P. R. China .
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9
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Flint A, Stintzi A, Saraiva LM. Oxidative and nitrosative stress defences of Helicobacter and Campylobacter species that counteract mammalian immunity. FEMS Microbiol Rev 2016; 40:938-960. [PMID: 28201757 PMCID: PMC5091033 DOI: 10.1093/femsre/fuw025] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/29/2016] [Accepted: 07/02/2016] [Indexed: 12/18/2022] Open
Abstract
Helicobacter and Campylobacter species are Gram-negative microaerophilic host-associated heterotrophic bacteria that invade the digestive tract of humans and animals. Campylobacter jejuni is the major worldwide cause of foodborne gastroenteritis in humans, while Helicobacter pylori is ubiquitous in over half of the world's population causing gastric and duodenal ulcers. The colonisation of the gastrointestinal system by Helicobacter and Campylobacter relies on numerous cellular defences to sense the host environment and respond to adverse conditions, including those imposed by the host immunity. An important antimicrobial tool of the mammalian innate immune system is the generation of harmful oxidative and nitrosative stresses to which pathogens are exposed during phagocytosis. This review summarises the regulators, detoxifying enzymes and subversion mechanisms of Helicobacter and Campylobacter that ultimately promote the successful infection of humans.
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Affiliation(s)
- Annika Flint
- Ottawa Institute of Systems Biology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Alain Stintzi
- Ottawa Institute of Systems Biology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Lígia M. Saraiva
- Instituto de Tecnologia Química e Biológica, NOVA, Av. da República, 2780-157 Oeiras, Portugal
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10
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Zorzoli A, Grayczyk JP, Alonzo F. Staphylococcus aureus Tissue Infection During Sepsis Is Supported by Differential Use of Bacterial or Host-Derived Lipoic Acid. PLoS Pathog 2016; 12:e1005933. [PMID: 27701474 PMCID: PMC5049849 DOI: 10.1371/journal.ppat.1005933] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/13/2016] [Indexed: 01/31/2023] Open
Abstract
To thrive in diverse environments, bacteria must shift their metabolic output in response to nutrient bioavailability. In many bacterial species, such changes in metabolic flux depend upon lipoic acid, a cofactor required for the activity of enzyme complexes involved in glycolysis, the citric acid cycle, glycine catabolism, and branched chain fatty acid biosynthesis. The requirement of lipoic acid for metabolic enzyme activity necessitates that bacteria synthesize the cofactor and/or scavenge it from environmental sources. Although use of lipoic acid is a conserved phenomenon, the mechanisms behind its biosynthesis and salvage can differ considerably between bacterial species. Furthermore, low levels of circulating free lipoic acid in mammals underscore the importance of lipoic acid acquisition for pathogenic microbes during infection. In this study, we used a genetic approach to characterize the mechanisms of lipoic acid biosynthesis and salvage in the bacterial pathogen Staphylococcus aureus and evaluated the requirements for both pathways during murine sepsis. We determined that S. aureus lipoic acid biosynthesis and salvage genes exist in an arrangement that directly links redox stress response and acetate biosynthesis genes. In addition, we found that lipoic acid salvage is dictated by two ligases that facilitate growth and lipoylation in distinct environmental conditions in vitro, but that are fully compensatory for survival in vivo. Upon infection of mice, we found that de novo biosynthesis or salvage promotes S. aureus survival in a manner that depends upon the infectious site. In addition, when both lipoic acid biosynthesis and salvage are blocked S. aureus is rendered avirulent, implying an inability to induce lipoic acid-independent metabolic programs to promote survival. Together, our results define the major pathways of lipoic acid biosynthesis and salvage in S. aureus and support the notion that bacterial nutrient acquisition schemes are instrumental in dictating pathogen proclivity for an infectious niche. Staphylococcus aureus is a predominant cause of infectious diseases ranging from superficial skin and soft tissue infections to necrotizing pneumonia and sepsis. A remarkable aspect of S. aureus pathobiology lies in the ability of the microorganism to infect a wide variety of host tissues. This infectious promiscuity implies S. aureus exhibits significant adaptability when faced with disparate environments and nutritional deficiencies. In this work, we examine the mechanisms by which S. aureus acquires lipoic acid, a key cofactor involved in maintaining metabolic flux. Our studies determine that S. aureus engages in both de novo biosynthesis and salvage of lipoic acid in a manner that is reminiscent of pathways used by both B. subtilis and L. monocytogenes combined. Further, our work suggests that the complex mechanisms of lipoic acid acquisition dictate the range of tissues S. aureus infects and identifies a lipoic acid salvage enzyme that is dispensable for growth in vitro, but required for S. aureus pathogenesis in vivo. In sum, our results highlight the adaptability of S. aureus in the face of nutrient paucity; the importance of complex nutrient acquisition/biosynthesis pathways in promoting infection; and identify potential novel therapeutic targets that may be effective against S. aureus.
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Affiliation(s)
- Azul Zorzoli
- Department of Microbiology and Immunology, Loyola University Chicago—Stritch School of Medicine, Maywood, Illinois, United States of America
| | - James P. Grayczyk
- Department of Microbiology and Immunology, Loyola University Chicago—Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago—Stritch School of Medicine, Maywood, Illinois, United States of America
- * E-mail:
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11
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Synthesis and Antimicrobial Evaluation of Amixicile-Based Inhibitors of the Pyruvate-Ferredoxin Oxidoreductases of Anaerobic Bacteria and Epsilonproteobacteria. Antimicrob Agents Chemother 2016; 60:3980-7. [PMID: 27090174 DOI: 10.1128/aac.00670-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 04/11/2016] [Indexed: 01/04/2023] Open
Abstract
Amixicile is a promising derivative of nitazoxanide (an antiparasitic therapeutic) developed to treat systemic infections caused by anaerobic bacteria, anaerobic parasites, and members of the Epsilonproteobacteria (Campylobacter and Helicobacter). Amixicile selectively inhibits pyruvate-ferredoxin oxidoreductase (PFOR) and related enzymes by inhibiting the function of the vitamin B1 cofactor (thiamine pyrophosphate) by a novel mechanism. Here, we interrogate the amixicile scaffold, guided by docking simulations, direct PFOR inhibition assays, and MIC tests against Clostridium difficile, Campylobacter jejuni, and Helicobacter pylori Docking simulations revealed that the nitro group present in nitazoxanide interacts with the protonated N4'-aminopyrimidine of thiamine pyrophosphate (TPP). The ortho-propylamine on the benzene ring formed an electrostatic interaction with an aspartic acid moiety (B456) of PFOR that correlated with improved PFOR-inhibitory activity and potency by MIC tests. Aryl substitution with electron-withdrawing groups and substitutions of the propylamine with other alkyl amines or nitrogen-containing heterocycles both improved PFOR inhibition and, in many cases, biological activity against C. difficile Docking simulation results correlate well with mechanistic enzymology and nuclear magnetic resonance (NMR) studies that show members of this class of antimicrobials to be specific inhibitors of vitamin B1 function by proton abstraction, which is both novel and likely to limit mutation-based drug resistance.
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12
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Behrens W, Schweinitzer T, McMurry JL, Loewen PC, Buettner FFR, Menz S, Josenhans C. Localisation and protein-protein interactions of the Helicobacter pylori taxis sensor TlpD and their connection to metabolic functions. Sci Rep 2016; 6:23582. [PMID: 27045738 PMCID: PMC4820699 DOI: 10.1038/srep23582] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/09/2016] [Indexed: 12/24/2022] Open
Abstract
The Helicobacter pylori energy sensor TlpD determines tactic behaviour under low energy conditions and is important in vivo. We explored protein-protein interactions of TlpD and their impact on TlpD localisation and function. Pull-down of tagged TlpD identified protein interaction partners of TlpD, which included the chemotaxis histidine kinase CheAY2, the central metabolic enzyme aconitase (AcnB) and the detoxifying enzyme catalase (KatA). We confirmed that KatA and AcnB physically interact with TlpD. While the TlpD-dependent behavioural response appeared not influenced in the interactor mutants katA and acnB in steady-state behavioural assays, acetone carboxylase subunit (acxC) mutant behaviour was altered. TlpD was localised in a bipolar subcellular pattern in media of high energy. We observed a significant change in TlpD localisation towards the cell body in cheAY2-, catalase- or aconitase-deficient bacteria or in bacteria incubated under low energy conditions, including oxidative stress or respiratory inhibition. Inactivation of tlpD resulted in an increased sensitivity to iron limitation and oxidative stress and influenced the H. pylori transcriptome. Oxidative stress, iron limitation and overexpressing the iron-sulfur repair system nifSU altered TlpD-dependent behaviour. We propose that TlpD localisation is instructed by metabolic activity and protein interactions, and its sensory activity is linked to iron-sulfur cluster integrity.
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Affiliation(s)
- Wiebke Behrens
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Tobias Schweinitzer
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Jonathan L McMurry
- Department of Molecular &Cellular Biology, Kennesaw State University, Kennesaw, GA, USA
| | - Peter C Loewen
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Falk F R Buettner
- Institute for Cellular Chemistry, Hannover Medical School, Hannover, Germany
| | - Sarah Menz
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Christine Josenhans
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany.,German Center of Infection Research, partner site Hannover-Braunschweig, Germany
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13
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Proteomics of the organohalide-respiring Epsilonproteobacterium Sulfurospirillum multivorans adapted to tetrachloroethene and other energy substrates. Sci Rep 2015; 5:13794. [PMID: 26387727 PMCID: PMC4585668 DOI: 10.1038/srep13794] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 08/05/2015] [Indexed: 12/15/2022] Open
Abstract
Organohalide respiration is an environmentally important but poorly characterized type of anaerobic respiration. We compared the global proteome of the versatile organohalide-respiring Epsilonproteobacterium Sulfurospirillum multivorans grown with different electron acceptors (fumarate, nitrate, or tetrachloroethene [PCE]). The most significant differences in protein abundance were found for gene products of the organohalide respiration region. This genomic region encodes the corrinoid and FeS cluster containing PCE reductive dehalogenase PceA and other proteins putatively involved in PCE metabolism such as those involved in corrinoid biosynthesis. The latter gene products as well as PceA and a putative quinol dehydrogenase were almost exclusively detected in cells grown with PCE. This finding suggests an electron flow from the electron donor such as formate or pyruvate via the quinone pool and a quinol dehydrogenase to PceA and the terminal electron acceptor PCE. Two putative accessory proteins, an IscU-like protein and a peroxidase-like protein, were detected with PCE only and might be involved in PceA maturation. The proteome of cells grown with pyruvate instead of formate as electron donor indicates a route of electrons from reduced ferredoxin via an Epsilonproteobacterial complex I and the quinone pool to PCE.
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14
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H. pylori virulence factors: influence on immune system and pathology. Mediators Inflamm 2014; 2014:426309. [PMID: 24587595 PMCID: PMC3918698 DOI: 10.1155/2014/426309] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/19/2013] [Indexed: 02/07/2023] Open
Abstract
Helicobacter pylori is the most widespread chronic bacterial agent in humans and is well recognized for its association with ulcer disease and gastric cancer, with both representing major global health and socioeconomic issues. Given the high level of adaptation and the coevolution of this bacterium with its human host, a thorough and multidirectional view of the specific microbiological characteristics of this infection as well as the host physiology is needed in order to develop novel means of prevention of therapy. This review aims to pinpoint some of these potentially important angles, which have to be considered mutually when studying H. pylori's pathogenicity. The host's biological changes due to the virulence factors are a valuable pillar of H. pylori research as are the mechanisms by which bacteria provoke these changes. In this context, necessary adhesion molecules and significant virulence factors of H. pylori are discussed. Moreover, metabolism of the bacteria, one of the most important aspects for a better understanding of bacterial physiology and consequently possible therapeutic and prophylactic strategies, is addressed. On the other hand, we discuss the recent experimental proofs of the "hygiene hypothesis" in correlation with Helicobacter's infection, which adds another aspect of complexity to this infection.
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15
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Kendall JJ, Barrero-Tobon AM, Hendrixson DR, Kelly DJ. Hemerythrins in the microaerophilic bacterium Campylobacter jejuni help protect key iron-sulphur cluster enzymes from oxidative damage. Environ Microbiol 2013; 16:1105-21. [PMID: 24245612 PMCID: PMC4257069 DOI: 10.1111/1462-2920.12341] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 11/12/2013] [Indexed: 01/27/2023]
Abstract
Microaerophilic bacteria are adapted to low oxygen environments, but the mechanisms by which their growth in air is inhibited are not well understood. The citric acid cycle in the microaerophilic pathogen Campylobacter jejuni is potentially vulnerable, as it employs pyruvate and 2-oxoglutarate:acceptor oxidoreductases (Por and Oor), which contain labile (4Fe-4S) centres. Here, we show that both enzymes are rapidly inactivated after exposure of cells to a fully aerobic environment. We investigated the mechanisms that might protect enzyme activity and identify a role for the hemerythrin HerA (Cj0241). A herA mutant exhibits an aerobic growth defect and reduced Por and Oor activities after exposure to 21% (v/v) oxygen. Slow anaerobic recovery of these activities after oxygen damage was observed, but at similar rates in both wild-type and herA strains, suggesting the role of HerA is to prevent Fe-S cluster damage, rather than promote repair. Another hemerythrin (HerB; Cj1224) also plays a protective role. Purified HerA and HerB exhibited optical absorption, ligand binding and resonance Raman spectra typical of μ-oxo-bridged di-iron containing hemerythrins. We conclude that oxygen lability and poor repair of Por and Oor are major contributors to microaerophily in C. jejuni; hemerythrins help prevent enzyme damage microaerobically or during oxygen transients.
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Affiliation(s)
- John J Kendall
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, UK
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16
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Galano JJ, Alías M, Pérez R, Velázquez-Campoy A, Hoffman PS, Sancho J. Improved Flavodoxin Inhibitors with Potential Therapeutic Effects against Helicobacter pylori Infection. J Med Chem 2013; 56:6248-58. [DOI: 10.1021/jm400786q] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Juan J. Galano
- Departamento
de Bioquímica
y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), Edificio I + D, Mariano Esquillor, 50018, Zaragoza, Spain
| | - Miriam Alías
- Departamento
de Bioquímica
y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), Edificio I + D, Mariano Esquillor, 50018, Zaragoza, Spain
| | - Reyes Pérez
- Departamento
de Bioquímica
y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), Edificio I + D, Mariano Esquillor, 50018, Zaragoza, Spain
| | - Adrian Velázquez-Campoy
- Departamento
de Bioquímica
y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), Edificio I + D, Mariano Esquillor, 50018, Zaragoza, Spain
- Fundación ARAID, Gobierno de Aragon, Aragon, Spain
| | - Paul S. Hoffman
- Department of Medicine, Division
of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, Virginia
22908, United States
| | - Javier Sancho
- Departamento
de Bioquímica
y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), Edificio I + D, Mariano Esquillor, 50018, Zaragoza, Spain
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17
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Sun Y, Li X, Li W, Zhao M, Wang L, Liu S, Zeng J, Liu Z, Jia J. Proteomic analysis of the function of spot in Helicobacter pylori anti-oxidative stress in vitro and colonization in vivo. J Cell Biochem 2013; 113:3393-402. [PMID: 22678710 DOI: 10.1002/jcb.24215] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
As a microaerobe, Helicobacter pylori employs the global regulator SpoT for defending against oxidative stress in vitro. However, the mechanisms how SpoT affects bacterial gene expression is still unknown. Moreover, the function of SpoT in H. pylori colonization in the host is remaining undetermined. To explore the functions of the SpoT in H. pylori pathogenesis, we constructed H. pylori 26695 spoT-deficient mutant (ΔspoT). While grown in ambient atmosphere, protein expression profile of the ΔspoT was analyzed with 2D gel electrophoresis and real-time PCR. Compared to the wild type, the spoT-deficient strain downregulated its transcription of the oxidative-induced genes, as well as the genes responsible for protein degradation and that related to energy metabolism. Meanwhile, the colonization ability of ΔspoT strains in Mongolian gerbil was tested, the results demonstrated a decayed colonization in the mouse stomach with ΔspoT than the wild type. As a matter of facts, the AGS cells infected with the ΔspoT strains excreted increased level of the gastric inflammation cytokines IL-8, and the ΔspoT strains showed poor survival ability when treated with reactive oxygen stress (sodium nitroprusside). The elevated capacity of stimulating cytokines and fragility to reactive oxygen stress may be contribute to decreased colonization of the spoT-deficient mutant in the mouse stomach. Conclusively, we speculate that spoT is a key regulator of the genes for H. pylori spreading in the air and colonization in host stomach.
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Affiliation(s)
- Yundong Sun
- Department of Microbiology, Key Laboratory for Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, China
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18
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Vitoriano I, Saraiva-Pava KD, Rocha-Gonçalves A, Santos A, Lopes AI, Oleastro M, Roxo-Rosa M. Ulcerogenic Helicobacter pylori strains isolated from children: a contribution to get insight into the virulence of the bacteria. PLoS One 2011; 6:e26265. [PMID: 22039453 PMCID: PMC3198394 DOI: 10.1371/journal.pone.0026265] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 09/23/2011] [Indexed: 12/15/2022] Open
Abstract
Infection with Helicobacter pylori is the major cause for the development of peptic ulcer disease (PUD). In children, with no other etiology for the disease, this rare event occurs shortly after infection. In these young patients, habits of smoking, diet, consumption of alcohol and non-steroid anti-inflammatory drugs and stress, in addition to the genetic susceptibility of the patient, represent a minor influence. Accordingly, the virulence of the implicated H. pylori strain should play a crucial role in the development of PUD. Corroborating this, our in vitro infection assays comparing a pool of five H. pylori strains isolated from children with PUD to a pool of five other pediatric clinical isolates associated with non-ulcer dyspepsia (NUD) showed the greater ability of PUD strains to induce a marked decrease in the viability of gastric cells and to cause severe damage in the cells cytoskeleton as well as an impairment in the production/secretion of mucins. To uncover virulence features, we compared the proteome of these two groups of H. pylori strains. Two-dimensional gel electrophoresis followed by mass-spectrometry allowed us to detect 27 differentially expressed proteins between them. In addition to the presence of genes encoding well established virulence factors, namely cagA, vacAs1, oipA “on” status, homB and jhp562 genes, the pediatric ulcerogenic strains shared a proteome profile characterized by changes in the abundance of: motility-associated proteins, accounting for higher motility; antioxidant proteins, which may confer increased resistance to inflammation; and enzymes involved in key steps in the metabolism of glucose, amino acids and urea, which may be advantageous to face fluctuations of nutrients. In conclusion, the enhanced virulence of the pediatric ulcerogenic H. pylori strains may result from a synergy between their natural ability to better adapt to the hostile human stomach and the expression of the established virulence factors.
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Affiliation(s)
- Inês Vitoriano
- Faculdade de Engenharia, Universidade Católica Portuguesa, Rio de Mouro, Portugal
| | | | | | - Andrea Santos
- Departamento de Doenças Infecciosas, Instituto Nacional Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Ana I. Lopes
- Departamento de Pediatria, Hospital Universitário de Santa Maria/Faculdade de Medicina de Lisboa, Lisboa, Portugal
| | - Mónica Oleastro
- Departamento de Doenças Infecciosas, Instituto Nacional Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Mónica Roxo-Rosa
- Faculdade de Engenharia, Universidade Católica Portuguesa, Rio de Mouro, Portugal
- * E-mail:
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19
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Mukherjee T, Boshoff H. Nitroimidazoles for the treatment of TB: past, present and future. Future Med Chem 2011; 3:1427-54. [PMID: 21879846 PMCID: PMC3225966 DOI: 10.4155/fmc.11.90] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Tuberculosis remains a leading cause of death resulting from an infectious agent, and the spread of multi- and extensively drug-resistant strains of Mycobacterium tuberculosis poses a threat to management of global health. New drugs that effectively shorten the duration of treatment and are active against drug-resistant strains of this pathogen are urgently required to develop effective chemotherapies to combat this disease. Two nitroimidazoles, PA-824 and OPC-67683, are currently in Phase II clinical trials for the treatment of TB and the outcome of these may determine the future directions of drug development for anti-tubercular nitroimidazoles. In this review we summarize the development of these nitroimidazoles and alternative analogs in these series that may offer attractive alternatives to PA-824 and OPC-67683 for further development in the drug-discovery pipeline. Lastly, the potential pitfalls in the development of nitroimidazoles as drugs for TB are discussed.
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Affiliation(s)
- Tathagata Mukherjee
- Tuberculosis Research Section, LCID, NIAID, NIH, Room 2W20G, Building 33, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Helena Boshoff
- Tuberculosis Research Section, LCID, NIAID, NIH, Room 2W20G, Building 33, 9000 Rockville Pike, Bethesda, MD 20892, USA
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20
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Bender G, Pierce E, Hill JA, Darty JE, Ragsdale SW. Metal centers in the anaerobic microbial metabolism of CO and CO2. Metallomics 2011; 3:797-815. [PMID: 21647480 PMCID: PMC3964926 DOI: 10.1039/c1mt00042j] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Carbon dioxide and carbon monoxide are important components of the carbon cycle. Major research efforts are underway to develop better technologies to utilize the abundant greenhouse gas, CO(2), for harnessing 'green' energy and producing biofuels. One strategy is to convert CO(2) into CO, which has been valued for many years as a synthetic feedstock for major industrial processes. Living organisms are masters of CO(2) and CO chemistry and, here, we review the elegant ways that metalloenzymes catalyze reactions involving these simple compounds. After describing the chemical and physical properties of CO and CO(2), we shift focus to the enzymes and the metal clusters in their active sites that catalyze transformations of these two molecules. We cover how the metal centers on CO dehydrogenase catalyze the interconversion of CO and CO(2) and how pyruvate oxidoreductase, which contains thiamin pyrophosphate and multiple Fe(4)S(4) clusters, catalyzes the addition and elimination of CO(2) during intermediary metabolism. We also describe how the nickel center at the active site of acetyl-CoA synthase utilizes CO to generate the central metabolite, acetyl-CoA, as part of the Wood-Ljungdahl pathway, and how CO is channelled from the CO dehydrogenase to the acetyl-CoA synthase active site. We cover how the corrinoid iron-sulfur protein interacts with acetyl-CoA synthase. This protein uses vitamin B(12) and a Fe(4)S(4) cluster to catalyze a key methyltransferase reaction involving an organometallic methyl-Co(3+) intermediate. Studies of CO and CO(2) enzymology are of practical significance, and offer fundamental insights into important biochemical reactions involving metallocenters that act as nucleophiles to form organometallic intermediates and catalyze C-C and C-S bond formations.
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Affiliation(s)
- Güneş Bender
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA. Fax: +1 734-763-4581; Tel: +1 734-615-4621
| | - Elizabeth Pierce
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA. Fax: +1 734-763-4581; Tel: +1 734-615-4621
| | - Jeffrey A. Hill
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA. Fax: +1 734-763-4581; Tel: +1 734-615-4621
| | - Joseph E. Darty
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA. Fax: +1 734-763-4581; Tel: +1 734-615-4621
| | - Stephen W. Ragsdale
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA. Fax: +1 734-763-4581; Tel: +1 734-615-4621
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21
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Bernarde C, Lehours P, Lasserre JP, Castroviejo M, Bonneu M, Mégraud F, Ménard A. Complexomics study of two Helicobacter pylori strains of two pathological origins: potential targets for vaccine development and new insight in bacteria metabolism. Mol Cell Proteomics 2010; 9:2796-826. [PMID: 20610778 PMCID: PMC3101863 DOI: 10.1074/mcp.m110.001065] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Indexed: 12/12/2022] Open
Abstract
Helicobacter pylori infection plays a causal role in the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma (LG-MALT) and duodenal ulcer (DU). Although many virulence factors have been associated with DU, many questions remain unanswered regarding the evolution of the infection toward this exceptional event, LG-MALT. The present study describes and compares the complexome of two H. pylori strains, strain J99 associated with DU and strain B38 associated with LG-MALT, using the two-dimensional blue native/SDS-PAGE method. It was possible to identify 90 different complexes (49 and 41 in the B38 and J99 strains, respectively); 12 of these complexes were common to both strains (seven and five in the membrane and cytoplasm, respectively), reflecting the variability of H. pylori strains. The 44 membrane complexes included numerous outer membrane proteins, such as the major adhesins BabA and SabA retrieved from a complex in the B38 strain, and also proteins from the hor family rarely studied. BabA and BabB adhesins were found to interact independently with HopM/N in the B38 and J99 strains, respectively. The 46 cytosolic complexes essentially comprised proteins involved in H. pylori physiology. Some orphan proteins were retrieved from heterooligomeric complexes, and a function could be proposed for a number of them via the identification of their partners, such as JHP0119, which may be involved in the flagellar function. Overall, this study gave new insights into the membrane and cytoplasm structure, and those which could help in the design of molecules for vaccine and/or antimicrobial agent development are highlighted.
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Affiliation(s)
- Cédric Bernarde
- From ‡INSERM U853, 33076 Bordeaux, France and
- §Laboratoire de Bactériologie
| | - Philippe Lehours
- From ‡INSERM U853, 33076 Bordeaux, France and
- §Laboratoire de Bactériologie
| | - Jean-Paul Lasserre
- From ‡INSERM U853, 33076 Bordeaux, France and
- §Laboratoire de Bactériologie
| | - Michel Castroviejo
- ‖Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, and
| | - Marc Bonneu
- **Pôle Protéomique, Plateforme Génomique Fonctionnelle, Université Victor Segalen Bordeaux 2, Bordeaux, F 33076 France
| | - Francis Mégraud
- From ‡INSERM U853, 33076 Bordeaux, France and
- §Laboratoire de Bactériologie
| | - Armelle Ménard
- From ‡INSERM U853, 33076 Bordeaux, France and
- §Laboratoire de Bactériologie
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22
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Abstract
Lipoic acid [(R)-5-(1,2-dithiolan-3-yl)pentanoic acid] is an enzyme cofactor required for intermediate metabolism in free-living cells. Lipoic acid was discovered nearly 60 years ago and was shown to be covalently attached to proteins in several multicomponent dehydrogenases. Cells can acquire lipoate (the deprotonated charge form of lipoic acid that dominates at physiological pH) through either scavenging or de novo synthesis. Microbial pathogens implement these basic lipoylation strategies with a surprising variety of adaptations which can affect pathogenesis and virulence. Similarly, lipoylated proteins are responsible for effects beyond their classical roles in catalysis. These include roles in oxidative defense, bacterial sporulation, and gene expression. This review surveys the role of lipoate metabolism in bacterial, fungal, and protozoan pathogens and how these organisms have employed this metabolism to adapt to niche environments.
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23
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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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24
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Cremades N, Velázquez-Campoy A, Martínez-Júlvez M, Neira JL, Pérez-Dorado I, Hermoso J, Jiménez P, Lanas A, Hoffman PS, Sancho J. Discovery of specific flavodoxin inhibitors as potential therapeutic agents against Helicobacter pylori infection. ACS Chem Biol 2009; 4:928-38. [PMID: 19725577 DOI: 10.1021/cb900166q] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Helicobacter pylori establishes life-long infections in the gastric mucosa of over 1 billion people worldwide. In many cases, without specific antimicrobial intervention, H. pylori infected individuals will develop type B gastritis, chronic peptic ulcers and, more rarely, gastric neoplasias. Conventional antimicrobial therapy has been complicated by dramatic increases in resistance to macrolides, metronidazole and fluoroquinolones. Here, we report the development of novel therapeutics that specifically target the unique flavodoxin component of an essential metabolic pathway of H. pylori. With the use of high-throughput screening methodology, we have tested 10,000 chemicals and have identified 29 compounds that bind flavodoxin, four of which interrupted in vitro electron transfer to flavodoxin physiological partners. Three of these compounds are bactericidal and promisingly selective for H. pylori. The minimal inhibitory concentrations of two of them are 10 times lower than their minimal cytotoxic concentrations for HeLa cells. Importantly, neither of the four inhibitors is toxic for mice after administration of 1-10 mg kg(-1) doses twice a day for 5 days. Enzymatic, thermodynamic and structural characterization of the inhibitor-flavodoxin complexes suggests these compounds could act by modifying the redox potentials of flavodoxin. These newly discovered inhibitors represent promising selective leads against the different diseases associated to H. pylori infection.
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Affiliation(s)
- Nunilo Cremades
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Spain
- Biocomputation and Complex Systems Physics Institute (BIFI)-Unidad Asociada al IQFR-CSIC, 50009 Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Biocomputation and Complex Systems Physics Institute (BIFI)-Unidad Asociada al IQFR-CSIC, 50009 Zaragoza, Spain
- Fundación Aragón I+D (ARAID-BIFI), Diputación General de Aragón, Spain
| | - Marta Martínez-Júlvez
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Spain
- Biocomputation and Complex Systems Physics Institute (BIFI)-Unidad Asociada al IQFR-CSIC, 50009 Zaragoza, Spain
| | - José L. Neira
- Biocomputation and Complex Systems Physics Institute (BIFI)-Unidad Asociada al IQFR-CSIC, 50009 Zaragoza, Spain
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | - Inmaculada Pérez-Dorado
- Grupo de Crystalografía Macromolecular y Biología Estructural, Instituto de Química-Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Juan Hermoso
- Grupo de Crystalografía Macromolecular y Biología Estructural, Instituto de Química-Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | | | - Angel Lanas
- IACS, CIBERehd, University of Zaragoza, Spain
| | - Paul S. Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia 22908
| | - Javier Sancho
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Spain
- Biocomputation and Complex Systems Physics Institute (BIFI)-Unidad Asociada al IQFR-CSIC, 50009 Zaragoza, Spain
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Shimomura H, Hosoda K, Hayashi S, Yokota K, Oguma K, Hirai Y. Steroids mediate resistance to the bactericidal effect of phosphatidylcholines against Helicobacter pylori. FEMS Microbiol Lett 2009; 301:84-94. [PMID: 19843309 DOI: 10.1111/j.1574-6968.2009.01807.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Helicobacter pylori assimilates various steroids as membrane lipid components, but it can also survive in the absence of steroids. It thus remains to be clarified as to why the organism relies on steroid physiologically. In this study, we have found that phosphatidylcholine carrying a linoleic acid molecule or arachidonic acid molecule has the potential to kill steroid-free H. pylori. The bactericidal action of phosphatidylcholines against H. pylori was due to the lytic activity of the phosphatidylcholines themselves and not due to the lytic activity of the unsaturated fatty acids or lyso-phosphatidylcholine resulting from the hydrolysis of the phosphatidylcholines. In contrast to the steroid-free H. pylori, the organism that absorbed and glucosylated free cholesterol was unaffected by the bactericidal action of the phosphatidylcholines. Similarly, H. pylori that absorbed estrone without glucosylating it also resisted the bactericidal action of the phosphatidylcholines. The steroids absorbed by H. pylori existed in both the outer and inner membranes, while the glucosyl-steroids produced via the steroid absorption were localized in the outer membrane rather than in the inner membrane. These results indicate that H. pylori absorbs the steroids to reinforce the membrane lipid barrier and thereby expresses resistance to the bacteriolytic action of hydrophobic compounds such as phosphatidylcholine.
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Affiliation(s)
- Hirofumi Shimomura
- Department of Infection and Immunity, Division of Bacteriology, Jichi Medical University, Tochigi, Japan.
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Guelker M, Stagg L, Wittung-Stafshede P, Shamoo Y. Pseudosymmetry, high copy number and twinning complicate the structure determination of Desulfovibrio desulfuricans (ATCC 29577) flavodoxin. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2009; 65:523-34. [PMID: 19465766 PMCID: PMC2685730 DOI: 10.1107/s0907444909010075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 03/18/2009] [Indexed: 11/10/2022]
Abstract
The crystal structure of oxidized flavodoxin from Desulfovibrio desulfuricans (ATCC 29577) was determined by molecular replacement in two crystal forms, P3(1)21 and P4(3), at 2.5 and 2.0 A resolution, respectively. Structure determination in space group P3(1)21 was challenging owing to the presence of pseudo-translational symmetry and a high copy number in the asymmetric unit (8). Initial phasing attempts in space group P3(1)21 by molecular replacement using a poor search model (46% identity) and multi-wavelength anomalous dispersion were unsuccessful. It was necessary to solve the structure in a second crystal form, space group P4(3), which was characterized by almost perfect twinning, in order to obtain a suitable search model for molecular replacement. This search model with complementary approaches to molecular replacement utilizing the pseudo-translational symmetry operators determined by analysis of the native Patterson map facilitated the selection and manual placement of molecules to generate an initial solution in the P3(1)21 crystal form. During the early stages of refinement, application of the appropriate twin law, (-h, -k, l), was required to converge to reasonable R-factor values despite the fact that in the final analysis the data were untwinned and the twin law could subsequently be removed. The approaches used in structure determination and refinement may be applicable to other crystal structures characterized by these complicating factors. The refined model shows flexibility of the flavin mononucleotide coordinating loops indicated by the isolation of two loop conformations and provides a starting point for the elucidation of the mechanism used for protein-partner recognition.
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Affiliation(s)
- Megan Guelker
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
| | - Loren Stagg
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
| | - Pernilla Wittung-Stafshede
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Yousif Shamoo
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
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Olekhnovich IN, Goodwin A, Hoffman PS. Characterization of the NAD(P)H oxidase and metronidazole reductase activities of the RdxA nitroreductase of Helicobacter pylori. FEBS J 2009; 276:3354-64. [PMID: 19438716 DOI: 10.1111/j.1742-4658.2009.07060.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Metronidazole (MTZ) is widely used in combination therapies against the human gastric pathogen Helicobacter pylori. Resistance to this drug is common among clinical isolates and results from loss-of-function mutations in rdxA, which encodes an oxygen-insensitive nitroreductase. The RdxA-associated MTZ-reductase activity of H. pylori is lost upon cell disruption. Here we provide a mechanistic explanation for this phenomenon. Under aerobic conditions, His6-tagged RdxA protein (purified from Escherichia coli), catalyzed NAD(P)H-dependent reductions of nitroaromatic and quinone substrates including nitrofurazone, nitrofurantoin, furazolidone, CB1954 and 1,4-benzoquinone, but not MTZ. Unlike other nitroreductases, His6-RdxA exhibited potent NAD(P)H-oxidase activity (k(cat) = 2.8 s(-1)) which suggested two possible explanations for the role of oxygen in MTZ reduction: (a) NAD(P)H-oxidase activity promotes cellular hypoxia (nonspecific reduction of MTZ), and (b) molecular oxygen out-competes MTZ for reducing equivalents. The first hypothesis was eliminated upon finding that rdxA expression, although increasing MTZ toxicity in both E. coli and H. pylori constructs, did not increase paraquat toxicity, even though both are of similar redox potential. The second hypothesis was confirmed by demonstrating NAD(P)H-dependent MTZ-reductase activity (apparent K(m) = 122 +/- 58 microM, k(cat) = 0.24 s(-1)) under strictly anaerobic conditions. The MTZ-reductase activity of RdxA was 60 times greater than for NfsB (E. coli NTR), but 10 times lower than the NADPH-oxidase activity. Whether molecular oxygen directly competes with MTZ or alters the redox state of the FMN cofactors is discussed.
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Affiliation(s)
- Igor N Olekhnovich
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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Kwon DH, Versalovic J. Fur-independent induction of Helicobacter pylori flavodoxin-encoding gene (fldA) under iron starvation. Helicobacter 2009; 14:141-6. [PMID: 19298342 DOI: 10.1111/j.1523-5378.2009.00669.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND AIMS Helicobacter pylori infection is associated with a variety of diseases including gastric cancer. Flavodoxin is an electron transfer protein containing a flavin mononucleotide prosthetic group and substituted an iron-containing electron transfer protein under iron-limiting conditions. H. pylori flavodoxin has been reported but its pathogenic role is unclear. The aim of this study is to understand a pathogenic role of H. pylori flavodoxin under iron-limiting condition. METHODS The flavodoxin-encoding gene (fldA) was cloned from one of clinical H. pylori isolates (DU17) and its transcript was quantified by primer extension, Northern hybridization, and real-time polymerase chain reaction in different concentrations of an iron chelator. The fldA transcript was also quantified in H. pylori ATCC 700392, lacking a ferric uptake regulatory (fur) protein. RESULT Nucleotide sequence of the fldA from H. pylori DU17 revealed a 492-bp (164 amino acids) open reading frame with a deduced amino acid sequence having 97% identity to that from the complete genomic sequence of H. pylori 26695. The deduced promoter [-35, -10, and +1] of the fldA was 56-bp upstream from the first codon of FldA. The fldA transcript (approximately 0.55-kb) was induced up to 14-fold in both wild-type and fur-knocked-out strains under iron-limiting conditions, suggesting that the fldA induction is independent to the Fur protein. CONCLUSION The fldA gene may play an important role in iron starvation conditions.
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Affiliation(s)
- Dong H Kwon
- Department of Biology, Long Island University, Brooklyn, New York 11201, USA.
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Ragsdale SW, Pierce E. Acetogenesis and the Wood-Ljungdahl pathway of CO(2) fixation. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1784:1873-98. [PMID: 18801467 PMCID: PMC2646786 DOI: 10.1016/j.bbapap.2008.08.012] [Citation(s) in RCA: 714] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 08/12/2008] [Accepted: 08/13/2008] [Indexed: 01/04/2023]
Abstract
Conceptually, the simplest way to synthesize an organic molecule is to construct it one carbon at a time. The Wood-Ljungdahl pathway of CO(2) fixation involves this type of stepwise process. The biochemical events that underlie the condensation of two one-carbon units to form the two-carbon compound, acetate, have intrigued chemists, biochemists, and microbiologists for many decades. We begin this review with a description of the biology of acetogenesis. Then, we provide a short history of the important discoveries that have led to the identification of the key components and steps of this usual mechanism of CO and CO(2) fixation. In this historical perspective, we have included reflections that hopefully will sketch the landscape of the controversies, hypotheses, and opinions that led to the key experiments and discoveries. We then describe the properties of the genes and enzymes involved in the pathway and conclude with a section describing some major questions that remain unanswered.
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Affiliation(s)
- Stephen W Ragsdale
- Department of Biological Chemistry, MSRB III, 5301, 1150 W. Medical Center Drive, University of Michigan, Ann Arbor, MI 48109-0606, USA.
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Pyruvate catabolism and hydrogen synthesis pathway genes of Clostridium thermocellum ATCC 27405. Indian J Microbiol 2008; 48:252-66. [PMID: 23100718 DOI: 10.1007/s12088-008-0036-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 06/12/2008] [Indexed: 10/21/2022] Open
Abstract
Clostridium thermocellum is a gram-positive, acetogenic, thermophilic, anaerobic bacterium that degrades cellulose and carries out mixed product fermentation, catabolising cellulose to acetate, lactate, and ethanol under various growth conditions, with the concomitant release of H(2) and CO(2). Very little is known about the factors that determine metabolic fluxes influencing H(2) synthesis in anaerobic, cellulolytic bacteria like C. thermocellum. We have begun to investigate the relationships between genome content, gene expression, and end-product synthesis in C. thermocellum cultured under different conditions. Using bioinformatics tools and the complete C. thermocellum 27405 genome sequence, we identified genes encoding key enzymes in pyruvate catabolism and H(2)-synthesis pathways, and have confirmed transcription of these genes throughout growth on α-cellulose by reverse transcriptase polymerase chain reaction. Bioinformatic analyses revealed two putative lactate dehydrogenases, one pyruvate formate lyase, four pyruvate:formate lyase activating enzymes, and at least three putative pyruvate:ferredoxin oxidoreductase (POR) or POR-like enzymes. Our data suggests that hydrogen may be generated through the action of either a Ferredoxin (Fd)-dependent NiFe hydrogenase, often referred to as "Energy-converting Hydrogenases", or via NAD(P)Hdependent Fe-only hydrogenases which would permit H(2) production from NADH generated during the glyceraldehyde-3-phosphate dehydrogenase reaction. Furthermore, our findings show the presence of a gene cluster putatively encoding a membrane integral NADH:Fd oxidoreductase, suggesting a possible mechanism in which electrons could be transferred between NADH and ferredoxin. The elucidation of pyruvate catabolism pathways and mechanisms of H(2) synthesis is the first step in developing strategies to increase hydrogen yields from biomass. Our studies have outlined the likely pathways leading to hydrogen synthesis in C. thermocellum strain 27405, but the actual functional roles of these gene products during pyruvate catabolism and in H 2 synthesis remain to be elucidated, and will need to be confirmed using both expression analysis and protein characterization.
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Cremades N, Bueno M, Neira JL, Velázquez-Campoy A, Sancho J. Conformational Stability of Helicobacter pylori Flavodoxin. J Biol Chem 2008; 283:2883-95. [DOI: 10.1074/jbc.m705677200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Brahmachary P, Wang G, Benoit SL, Weinberg MV, Maier RJ, Hoover TR. The human gastric pathogen Helicobacter pylori has a potential acetone carboxylase that enhances its ability to colonize mice. BMC Microbiol 2008; 8:14. [PMID: 18215283 PMCID: PMC2244623 DOI: 10.1186/1471-2180-8-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 01/23/2008] [Indexed: 01/04/2023] Open
Abstract
Background Helicobacter pylori colonizes the human stomach and is the etiological agent of peptic ulcer disease. All three H. pylori strains that have been sequenced to date contain a potential operon whose products share homology with the subunits of acetone carboxylase (encoded by acxABC) from Xanthobacter autotrophicus strain Py2 and Rhodobacter capsulatus strain B10. Acetone carboxylase catalyzes the conversion of acetone to acetoacetate. Genes upstream of the putative acxABC operon encode enzymes that convert acetoacetate to acetoacetyl-CoA, which is metabolized further to generate two molecules of acetyl-CoA. Results To determine if the H. pylori acxABC operon has a role in host colonization the acxB homolog in the mouse-adapted H. pylori SS1 strain was inactivated with a chloramphenicol-resistance (cat) cassette. In mouse colonization studies the numbers of H. pylori recovered from mice inoculated with the acxB:cat mutant were generally one to two orders of magnitude lower than those recovered from mice inoculated with the parental strain. A statistical analysis of the data using a Wilcoxin Rank test indicated the differences in the numbers of H. pylori isolated from mice inoculated with the two strains were significant at the 99% confidence level. Levels of acetone associated with gastric tissue removed from uninfected mice were measured and found to range from 10–110 μmols per gram wet weight tissue. Conclusion The colonization defect of the acxB:cat mutant suggests a role for the acxABC operon in survival of the bacterium in the stomach. Products of the H. pylori acxABC operon may function primarily in acetone utilization or may catalyze a related reaction that is important for survival or growth in the host. H. pylori encounters significant levels of acetone in the stomach which it could use as a potential electron donor for microaerobic respiration.
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The Campylobacter jejuni NADH:ubiquinone oxidoreductase (complex I) utilizes flavodoxin rather than NADH. J Bacteriol 2007; 190:915-25. [PMID: 18065531 DOI: 10.1128/jb.01647-07] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Campylobacter jejuni encodes 12 of the 14 subunits that make up the respiratory enzyme NADH:ubiquinone oxidoreductase (also called complex I). The two nuo genes not present in C. jejuni encode the NADH dehydrogenase, and in their place in the operon are the novel genes designated Cj1575c and Cj1574c. A series of mutants was generated in which each of the 12 nuo genes (homologues to known complex I subunits) was disrupted or deleted. Each of the nuo mutants will not grow in amino acid-based medium unless supplemented with an alternative respiratory substrate such as formate. Unlike the nuo genes, Cj1574c is an essential gene and could not be disrupted unless an intact copy of the gene was provided at an unrelated site on the chromosome. A nuo deletion mutant can efficiently respire formate but is deficient in alpha-ketoglutarate respiratory activity compared to the wild type. In C. jejuni, alpha-ketoglutarate respiration is mediated by the enzyme 2-oxoglutarate:acceptor oxidoreductase; mutagenesis of this enzyme abolishes alpha-ketoglutarate-dependent O2 uptake and fails to reduce the electron transport chain. The electron acceptor for 2-oxoglutarate:acceptor oxidoreductase was determined to be flavodoxin, which was also determined to be an essential protein in C. jejuni. A model is presented in which CJ1574 mediates electron flow into the respiratory transport chain from reduced flavodoxin and through complex I.
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St Maurice M, Cremades N, Croxen MA, Sisson G, Sancho J, Hoffman PS. Flavodoxin:quinone reductase (FqrB): a redox partner of pyruvate:ferredoxin oxidoreductase that reversibly couples pyruvate oxidation to NADPH production in Helicobacter pylori and Campylobacter jejuni. J Bacteriol 2007; 189:4764-73. [PMID: 17468253 PMCID: PMC1913460 DOI: 10.1128/jb.00287-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pyruvate-dependent reduction of NADP has been demonstrated in cell extracts of the human gastric pathogen Helicobacter pylori. However, NADP is not a substrate of purified pyruvate:ferredoxin oxidoreductase (PFOR), suggesting that other redox active enzymes mediate this reaction. Here we show that fqrB (HP1164), which is essential and highly conserved among the epsilonproteobacteria, exhibits NADPH oxidoreductase activity. FqrB was purified by nickel interaction chromatography following overexpression in Escherichia coli. The protein contained flavin adenine dinucleotide and exhibited NADPH quinone reductase activity with menadione or benzoquinone and weak activity with cytochrome c, molecular oxygen, and 5,5'-dithio-bis-2-nitrobenzoic acid (DTNB). FqrB exhibited a ping-pong catalytic mechanism, a k(cat) of 122 s(-1), and an apparent K(m) of 14 muM for menadione and 26 muM for NADPH. FqrB also reduced flavodoxin (FldA), the electron carrier of PFOR. In coupled enzyme assays with purified PFOR and FldA, FqrB reduced NADP in a pyruvate- and reduced coenzyme A (CoA)-dependent manner. Moreover, in the presence of NADPH, CO(2), and acetyl-CoA, the PFOR:FldA:FqrB complex generated pyruvate via CO(2) fixation. PFOR was the rate-limiting enzyme in the complex, and nitazoxanide, a specific inhibitor of PFOR of H. pylori and Campylobacter jejuni, also inhibited NADP reduction in cell-free lysates. These capnophilic (CO(2)-requiring) organisms contain gaps in pathways of central metabolism that would benefit substantially from pyruvate formation via CO(2) fixation. Thus, FqrB provides a novel function in pyruvate metabolism and, together with production of superoxide anions via quinone reduction under high oxygen tensions, contributes to the unique microaerobic lifestyle that defines the epsilonproteobacterial group.
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Affiliation(s)
- Martin St Maurice
- Department of Medicine, Division of Infectious Diseases, University of Virginia Health Systems, 409 Lane Road, Charlottesville, VA 22908, USA
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Shimomura H, Hayashi S, Yokota K, Oguma K, Hirai Y. Conversion of flavodoxin from holoenzyme to apoprotein during growth phase changes in Helicobacter pylori. J Bacteriol 2007; 189:4960-3. [PMID: 17449605 PMCID: PMC1913443 DOI: 10.1128/jb.00272-07] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The catabolic pathway for flavodoxin has yet to be clarified for any bacterial species. In this study, we found that the flavin mononucleotide in the flavodoxin of Helicobacter pylori is degraded to riboflavin via the phosphomonoesterase activity of class C acid phosphatase. The result is a conversion of holoflavodoxin to apoflavodoxin.
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Affiliation(s)
- Hirofumi Shimomura
- Division of Bacteriology, Department of Infection and Immunity, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan.
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Hoffman PS, Sisson G, Croxen MA, Welch K, Harman WD, Cremades N, Morash MG. Antiparasitic drug nitazoxanide inhibits the pyruvate oxidoreductases of Helicobacter pylori, selected anaerobic bacteria and parasites, and Campylobacter jejuni. Antimicrob Agents Chemother 2006; 51:868-76. [PMID: 17158936 PMCID: PMC1803158 DOI: 10.1128/aac.01159-06] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nitazoxanide (NTZ) exhibits broad-spectrum activity against anaerobic bacteria and parasites and the ulcer-causing pathogen Helicobacter pylori. Here we show that NTZ is a noncompetitive inhibitor (K(i), 2 to 10 microM) of the pyruvate:ferredoxin/flavodoxin oxidoreductases (PFORs) of Trichomonas vaginalis, Entamoeba histolytica, Giardia intestinalis, Clostridium difficile, Clostridium perfringens, H. pylori, and Campylobacter jejuni and is weakly active against the pyruvate dehydrogenase of Escherichia coli. To further mechanistic studies, the PFOR operon of H. pylori was cloned and overexpressed in E. coli, and the multisubunit complex was purified by ion-exchange chromatography. Pyruvate-dependent PFOR activity with NTZ, as measured by a decrease in absorbance at 418 nm (spectral shift from 418 to 351 nm), unlike the reduction of viologen dyes, did not result in the accumulation of products (acetyl coenzyme A and CO(2)) and pyruvate was not consumed in the reaction. NTZ did not displace the thiamine pyrophosphate (TPP) cofactor of PFOR, and the 351-nm absorbing form of NTZ was inactive. Optical scans and (1)H nuclear magnetic resonance analyses determined that the spectral shift (A(418) to A(351)) of NTZ was due to protonation of the anion (NTZ(-)) of the 2-amino group of the thiazole ring which could be generated with the pure compound under acidic solutions (pK(a) = 6.18). We propose that NTZ(-) intercepts PFOR at an early step in the formation of the lactyl-TPP transition intermediate, resulting in the reversal of pyruvate binding prior to decarboxylation and in coordination with proton transfer to NTZ. Thus, NTZ might be the first example of an antimicrobial that targets the "activated cofactor" of an enzymatic reaction rather than its substrate or catalytic sites, a novel mechanism that may escape mutation-based drug resistance.
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Affiliation(s)
- Paul S Hoffman
- Division of Infectious Diseases and International Health, 409 Lane Road, University of Virginia Health Systems, Charlottesville, VA 22908-1340, USA.
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Pyndiah S, Lasserre JP, Ménard A, Claverol S, Prouzet-Mauléon V, Mégraud F, Zerbib F, Bonneu M. Two-dimensional blue native/SDS gel electrophoresis of multiprotein complexes from Helicobacter pylori. Mol Cell Proteomics 2006; 6:193-206. [PMID: 17092930 DOI: 10.1074/mcp.m600363-mcp200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The study of protein interactions constitutes an important domain to understand the physiology and pathogenesis of microorganisms. The two-dimensional blue native/SDS-PAGE was initially reported to analyze membrane protein complexes. In this study, both cytoplasmic and membrane complexes of a bacterium, the strain J99 of the gastric pathogen Helicobacter pylori, were analyzed by this method. It was possible to identify 34 different proteins grouped in 13 multiprotein complexes, 11 from the cytoplasm and two from the membrane, either previously reported partially or totally in the literature. Besides complexes involved in H. pylori physiology, this method allowed the description of interactions involving known pathogenic factors such as (i) urease with the heat shock protein GroEL or with the putative ketol-acid reductoisomerase IlvC and (ii) the cag pathogenicity island CagA protein with the DNA gyrase GyrA as well as insight on the partners of TsaA, a peroxide reductase/stress-dependent molecular chaperone. The two-dimensional blue native/SDS-PAGE combined with mass spectrometry is a potential tool to study the differences in complexes isolated in various situations and also to study the interactions between bacterial and eucaryotic cell proteins.
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Astashkin AV, Seravalli J, Mansoorabadi SO, Reed GH, Ragsdale SW. Pulsed electron paramagnetic resonance experiments identify the paramagnetic intermediates in the pyruvate ferredoxin oxidoreductase catalytic cycle. J Am Chem Soc 2006; 128:3888-9. [PMID: 16551078 PMCID: PMC3119504 DOI: 10.1021/ja0585275] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyruvate ferredoxin oxidoreductase (PFOR) is central to the anaerobic metabolism of many bacteria and amitochondriate eukaryotes. PFOR contains thiamine pyrophosphate (TPP) and three [4Fe-4S] clusters, which link pyruvate oxidation to reduction of ferredoxin. In the PFOR reaction, TPP reacts with pyruvate to form lactyl-TPP, which undergoes decarboxylation to form a hydroxyethyl-TPP (HE-TPP) intermediate. One electron is then transferred from HE-TPP to one of the three [4Fe-4S] clusters to form an HE-TPP radical and a [4Fe-4S]1+ intermediate. Pulsed EPR methods have been used to measure the distance between the HE-TPP radical and the [4Fe-4S]1+ cluster to which it is coupled. Computational analysis including the PFOR crystal structure and the spin distribution in the HE-TPP radical and in the reduced [4Fe-4S] cluster demonstrates that the distance between the HE-TPP radical and the medial cluster B matches the experimentally determined dipolar interaction, while one of the other two clusters is too close and the other is too far away. These results clearly demonstrate that it is the medial cluster (cluster B) that is reduced. Thus, rapid electron transfer occurs through the electron-transfer chain, which leaves an oxidized proximal cluster poised to accept an electron from the HE-TPP radical in the subsequent reaction step.
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Affiliation(s)
- Andrei V Astashkin
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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Liu YQ, Han J, Epstein PN, Long YS. Enhanced rat beta-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway. Am J Physiol Endocrinol Metab 2005; 288:E471-8. [PMID: 15507531 DOI: 10.1152/ajpendo.00427.2004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Islet beta-cell proliferation is a very important component of beta-cell adaptation to insulin resistance and prevention of type 2 diabetes mellitus. However, we know little about the mechanisms of beta-cell proliferation. We now investigate the relationship between pyruvate carboxylase (PC) pathway activity and islet cell proliferation 5 days after 60% pancreatectomy (Px). Islet cell number, protein, and DNA content, indicators of beta-cell proliferation, were increased two- to threefold 5 days after Px. PC and pyruvate dehydrogenase (PDH) activities increased only approximately 1.3-fold; however, islet pyruvate content and malate release from isolated islet mitochondria were approximately threefold increased in Px islets. The latter is an indicator of pyruvate-malate cycle activity, indicating that most of the increased pyruvate was converted to oxaloacetate (OAA) through the PC pathway. The contents of OAA and malate, intermediates of the pyruvate-malate cycle, were also increased threefold. PDH and citrate content were only slightly increased. Importantly, the changes in cell proliferation parameters, glucose utilization, and oxidation and malate release were partially blocked by in vivo treatment with the PC inhibitor phenylacetic acid. Our results suggest that enhanced PC pathway in Px islets may have an important role in islet cell proliferation.
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Affiliation(s)
- Y Q Liu
- Kosair Children's Hospital Research Institute, Dept. of Pediatrics, Univ. of Louisville School of Medicine, 570 South Preston St., Suite 304, Louisville, KY 40292, USA.
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Abstract
This review focuses on how microbes live on CO as a sole source of carbon and energy and with CO by generating carbon monoxide as a metabolic intermediate. The use of CO is a property of organisms that use the Wood-L jungdahl pathway of autotrophic growth. The review discusses when CO metabolism originated, when and how it was discovered, and what properties of CO are ideal for microbial growth. How CO sensing by a heme-containing transcriptional regulatory protein activates the expression of CO metabolism-linked genes is described. Two metalloenzymes are the cornerstones of growth with CO: CO dehydrogenase (CODH) and acetyl-CoA synthase (ACS). CODH oxidizes CO to CO2, providing low-potential electrons for the cell, or alternatively reduces CO2 to CO. The latter reaction, when coupled to ACS, forms a machine for generating acetyl-CoA from CO2 for cell carbon synthesis. The recently solved crystal structures of CODH and ACS along with spectroscopic measurements and computational studies provide insights into novel bio-organometallic catalytic mechanisms and into the nature of a 140 A gas channel that coordinates the generation and utilization of CO. The enzymes that are coupled to CODH/ACS are also described, with a focus on a corrinoid protein, a methyltransferase, and pyruvate ferredoxin oxidoreductase.
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Affiliation(s)
- Stephen W Ragsdale
- Department of Biochemistry, Beadle Center, University of Nebraska, Lincoln, NE 68588-0664, USA.
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41
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Gaynor EC, Cawthraw S, Manning G, MacKichan JK, Falkow S, Newell DG. The genome-sequenced variant of Campylobacter jejuni NCTC 11168 and the original clonal clinical isolate differ markedly in colonization, gene expression, and virulence-associated phenotypes. J Bacteriol 2004; 186:503-17. [PMID: 14702320 PMCID: PMC305761 DOI: 10.1128/jb.186.2.503-517.2004] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The genome sequence of the enteric bacterial pathogen Campylobacter jejuni NCTC 11168 (11168-GS) was published in 2000, providing a valuable resource for the identification of C. jejuni-specific colonization and virulence factors. Surprisingly, the 11168-GS clone was subsequently found to colonize 1-day-old chicks following oral challenge very poorly compared to other strains. In contrast, we have found that the original clinical isolate from which 11168-GS was derived, 11168-O, is an excellent colonizer of chicks. Other marked phenotypic differences were also identified: 11168-O invaded and translocated through tissue culture cells far more efficiently and rapidly than 11168-GS, was significantly more motile, and displayed a different morphology. Serotyping, multiple high-resolution molecular genotyping procedures, and subtractive hybridization did not yield observable genetic differences between the variants, suggesting that they are clonal. However, microarray transcriptional profiling of these strains under microaerobic and severely oxygen-limited conditions revealed dramatic expression differences for several gene families. Many of the differences were in respiration and metabolism genes and operons, suggesting that adaptation to different oxygen tensions may influence colonization potential. This correlates biologically with our observation that anaerobically priming 11168-GS or aerobically passaging 11168-O caused an increase or decrease, respectively, in colonization compared to the parent strain. Expression differences were also observed for several flagellar genes and other less well-characterized genes that may participate in motility. Targeted sequencing of the sigma factors revealed specific DNA differences undetected by the other genomic methods [corrected].
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Affiliation(s)
- Erin C Gaynor
- Department of Microbiology and Immunology, Stanford University, Stanford, California, USA.
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42
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Nagata K, Nagata Y, Sato T, Fujino MA, Nakajima K, Tamura T. L-Serine, D- and L-proline and alanine as respiratory substrates of Helicobacter pylori: correlation between in vitro and in vivo amino acid levels. MICROBIOLOGY (READING, ENGLAND) 2003; 149:2023-2030. [PMID: 12904542 DOI: 10.1099/mic.0.26203-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Helicobacter pylori whole cells showed high rates of oxygen uptake with L-serine and L-proline as respiratory substrates, and somewhat lower rates with D-alanine and D-proline. These respiratory activities were inhibited by rotenone and antimycin A at low concentrations. Since pyruvate was produced from L-serine and D- and L-alanine in whole cells, the respiratory activities with these amino acids as substrates occurred via pyruvate. Whole cells showed 2,6-dichlorophenolindophenol (DCIP)-reducing activities with D- and L-proline and D-alanine as substrates, suggesting that hydrogen removed from these amino acids also participated in oxygen uptake by the whole cells. High amounts of L-proline, D- and L-alanine, and L-serine were present in H. pylori cells, and these amino acids also predominated in samples of human gastric juice. H. pylori seems to utilize D- and L-proline, D-alanine and L-serine as important energy sources in its habitat of the mucous layer of the stomach.
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Affiliation(s)
- Kumiko Nagata
- Department of Bacteriology, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
| | - Yoko Nagata
- Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14 Kanda, Surugadai, Chiyoda-ku, Tokyo 101-8308, Japan
| | - Tadashi Sato
- First Department of Medicine, Yamanashi Medical University, Kofu, Yamanashi, 409-3898, Japan
| | - Masayuki A Fujino
- First Department of Medicine, Yamanashi Medical University, Kofu, Yamanashi, 409-3898, Japan
| | - Kazuhiko Nakajima
- Department of Bacteriology, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
| | - Toshihide Tamura
- Department of Bacteriology, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo 663-8501, Japan
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43
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Affiliation(s)
- Stephen W Ragsdale
- Department of Biochemistry, Beadle Center, 19th and Vine Streets, University of Nebraska, Lincoln, Nebraska 68588-0664, USA.
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44
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Marais A, Bilardi C, Cantet F, Mendz GL, Mégraud F. Characterization of the genes rdxA and frxA involved in metronidazole resistance in Helicobacter pylori. Res Microbiol 2003; 154:137-44. [PMID: 12648728 DOI: 10.1016/s0923-2508(03)00030-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Metronidazole (Mtz) resistance in Helicobacter pylori has been found to be associated with mutations in rdxA, a gene encoding an oxygen-insensitive NADPH nitroreductase, and enhanced by mutations in frxA, a gene encoding a NAD(P)H-flavin oxidoreductase. The roles of these two genes in Mtz resistance in H. pylori were examined in this study. The rdxA and frxA genes were sequenced in nine pairs of strains isolated from biopsies obtained from patients before and after failed eradication treatments which included Mtz and resulted in the appearance of resistant strains. Metronidazole resistance could be explained in seven of these pairs of strains by mutations in rdxA and frxA. However, in one pair of strains, rdxA was identical in the susceptible and resistant strains, and only changes in frxA were observed; and in another pair, neither rdxA nor frxA were different in the susceptible and resistant strains. Sequencing of the upstream region of frxA and of the recA gene in the latter pair of strains did not reveal any mutations. To establish whether mutations in frxA alone could be involved in Mtz resistance, a resistant Escherichia coli strain transformed with the frxA of a Mtz susceptible H. pylori strain was rendered susceptible, and transformation with a mutated H. pylori frxA gene under the same conditions did not change the resistant E. coli phenotype. The results suggested that a Mtz resistance phenotype may arise in H. pylori without mutations in rdxA or frxA, or with mutations only in frxA.
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Affiliation(s)
- Armelle Marais
- Laboratoire de Bactériologie, Université Victor Segalen Bordeaux 2, 146, rue Léo Saignat, 33076 Bordeaux, France
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45
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Abstract
Acetyl-CoA carboxylase (ACC) catalyses the first committed step of fatty acid synthesis, the carboxylation of acetyl-CoA to malonyl-CoA. Two physically distinct types of enzymes are found in nature. Bacterial and most plant chloroplasts contain a multi-subunit ACC (MS-ACC) enzyme that is readily dissociated into its component proteins. Mammals, fungi, and plant cytosols contain the second type of ACC, a single large multifunctional polypeptide. This review will focus on the structures, regulation, and enzymatic mechanisms of the bacterial and plant MS-ACCs.
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Affiliation(s)
- John E Cronan
- Department of Microbiology, B103 Chemical and Life Sciences Laboratory, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.
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46
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Schilling CH, Covert MW, Famili I, Church GM, Edwards JS, Palsson BO. Genome-scale metabolic model of Helicobacter pylori 26695. J Bacteriol 2002; 184:4582-93. [PMID: 12142428 PMCID: PMC135230 DOI: 10.1128/jb.184.16.4582-4593.2002] [Citation(s) in RCA: 223] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A genome-scale metabolic model of Helicobacter pylori 26695 was constructed from genome sequence annotation, biochemical, and physiological data. This represents an in silico model largely derived from genomic information for an organism for which there is substantially less biochemical information available relative to previously modeled organisms such as Escherichia coli. The reconstructed metabolic network contains 388 enzymatic and transport reactions and accounts for 291 open reading frames. Within the paradigm of constraint-based modeling, extreme-pathway analysis and flux balance analysis were used to explore the metabolic capabilities of the in silico model. General network properties were analyzed and compared to similar results previously generated for Haemophilus influenzae. A minimal medium required by the model to generate required biomass constituents was calculated, indicating the requirement of eight amino acids, six of which correspond to essential human amino acids. In addition a list of potential substrates capable of fulfilling the bulk carbon requirements of H. pylori were identified. A deletion study was performed wherein reactions and associated genes in central metabolism were deleted and their effects were simulated under a variety of substrate availability conditions, yielding a number of reactions that are deemed essential. Deletion results were compared to recently published in vitro essentiality determinations for 17 genes. The in silico model accurately predicted 10 of 17 deletion cases, with partial support for additional cases. Collectively, the results presented herein suggest an effective strategy of combining in silico modeling with experimental technologies to enhance biological discovery for less characterized organisms and their genomes.
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47
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Bao Q, Tian Y, Li W, Xu Z, Xuan Z, Hu S, Dong W, Yang J, Chen Y, Xue Y, Xu Y, Lai X, Huang L, Dong X, Ma Y, Ling L, Tan H, Chen R, Wang J, Yu J, Yang H. A complete sequence of the T. tengcongensis genome. Genome Res 2002; 12:689-700. [PMID: 11997336 PMCID: PMC186588 DOI: 10.1101/gr.219302] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Thermoanaerobacter tengcongensis is a rod-shaped, gram-negative, anaerobic eubacterium that was isolated from a freshwater hot spring in Tengchong, China. Using a whole-genome-shotgun method, we sequenced its 2,689,445-bp genome from an isolate, MB4(T) (Genbank accession no. AE008691). The genome encodes 2588 predicted coding sequences (CDS). Among them, 1764 (68.2%) are classified according to homology to other documented proteins, and the rest, 824 CDS (31.8%), are functionally unknown. One of the interesting features of the T. tengcongensis genome is that 86.7% of its genes are encoded on the leading strand of DNA replication. Based on protein sequence similarity, the T. tengcongensis genome is most similar to that of Bacillus halodurans, a mesophilic eubacterium, among all fully sequenced prokaryotic genomes up to date. Computational analysis on genes involved in basic metabolic pathways supports the experimental discovery that T. tengcongensis metabolizes sugars as principal energy and carbon source and utilizes thiosulfate and element sulfur, but not sulfate, as electron acceptors. T. tengcongensis, as a gram-negative rod by empirical definitions (such as staining), shares many genes that are characteristics of gram-positive bacteria whereas it is missing molecular components unique to gram-negative bacteria. A strong correlation between the G + C content of tDNA and rDNA genes and the optimal growth temperature is found among the sequenced thermophiles. It is concluded that thermophiles are a biologically and phylogenetically divergent group of prokaryotes that have converged to sustain extreme environmental conditions over evolutionary timescale.
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Affiliation(s)
- Qiyu Bao
- Beijing Genomics Institute/Genomics and Bioinformatics Center, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China
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48
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Freigang J, Diederichs K, Schäfer KP, Welte W, Paul R. Crystal structure of oxidized flavodoxin, an essential protein in Helicobacter pylori. Protein Sci 2002; 11:253-61. [PMID: 11790835 PMCID: PMC2373437 DOI: 10.1110/ps.28602] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The redox protein flavodoxin has been shown earlier to be reduced by the pyruvate-oxidoreductase (POR) enzyme complex of Helicobacter pylori, and also was proposed to be involved in the pathogenesis of gastric mucosa-associated lymphoid-tissue lymphoma (MALToma). Here, we report its X-ray structure, which is similar to flavodoxins of other bacteria and cyanobacteria. However, H. pylori flavodoxin has an alanine residue near the isoalloxazine ring of its cofactor flavin mononucleotide (FMN), while the other previously crystallized flavodoxins have a larger hydrophobic residue at this position. This creates a solute filled hole near the FMN cofactor of H. pylori flavodoxin. We also show that flavodoxin is essential for the survival of H. pylori, and conclude that its structure can be used as a starting point for the modeling of an inhibitor for the interaction between the POR-enzyme complex and flavodoxin.
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Affiliation(s)
- Jörg Freigang
- Fachbereich Biologie, Universität Konstanz, D-78457 Konstanz, Germany
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49
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Abstract
Modern triple drug regimens are highly effective for treating Helicobacter pylori infection, but bacterial resistance to one of the most effective antibiotics, metronidazole, is a serious and increasing problem. The activity of metronidazole in H. pylori is dependent on reduction of its nitro moiety to highly reactive compounds that cause DNA strand breakage. The acquisition of resistance is highly associated with mutational inactivation of the rdxA gene, which encodes an oxygen-insensitive NADPH nitroreductase. Recent evidence has suggested that inactivation of frxA (NADPH flavin oxidoreductase), fdxB (ferredoxin-like protein) and possibly other reductase-encoding genes may also contribute to the resistant phenotype. Improved understanding of the mechanisms of metronidazole resistance in H. pylori is essential for the development and validation of biopsy-based tests for detection of resistance in clinical practice.
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Affiliation(s)
- Peter J Jenks
- Institute of Infections and Immunity, Queen's Medical Centre, University Hospital, Floor C, West Block, NG7 2UH, Nottingham, UK.
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50
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Yoon KS, Bobst C, Hemann CF, Hille R, Tabita FR. Spectroscopic and functional properties of novel 2[4Fe-4S] cluster-containing ferredoxins from the green sulfur bacterium Chlorobium tepidum. J Biol Chem 2001; 276:44027-36. [PMID: 11568186 DOI: 10.1074/jbc.m107852200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two distinct ferredoxins, Fd I and Fd II, were isolated and purified to homogeneity from photoautotrophically grown Chlorobium tepidum, a moderately thermophilic green sulfur bacterium that assimilates carbon dioxide by the reductive tricarboxylic acid cycle. Both ferredoxins serve a crucial role as electron donors for reductive carboxylation, catalyzed by a key enzyme of this pathway, pyruvate synthase/pyruvate ferredoxin oxidoreductase. The reduction potentials of Fd I and Fd II were determined by cyclic voltammetry to be -514 and -584 mV, respectively, which are more electronegative than any previously studied Fds in which two [4Fe-4S] clusters display a single transition. Further spectroscopic studies indicated that the CD spectrum of oxidized Fd I closely resembled that of Fd II; however, both spectra appeared to be unique relative to ferredoxins studied previously. Double integration of the EPR signal of the two Fds yielded approximately approximately 2.0 spins per molecule, compatible with the idea that C. tepidum Fd I and Fd II accept 2 electrons upon reduction. These results suggest that the C. tepidum Fd I and Fd II polypeptides each contain two bound [4Fe-4S] clusters. C. tepidum Fd I and Fd II are novel 2[4Fe-4S] Fds, which were shown previously to function as biological electron donors or acceptors for C. tepidum pyruvate synthase/pyruvate ferredoxin oxidoreductase (Yoon, K.-S., Hille, R., Hemann, C. F., and Tabita, F. R. (1999) J. Biol. Chem. 274, 29772-29778). Kinetic measurements indicated that Fd I had approximately 2.3-fold higher affinity than Fd II. The results of amino acid sequence alignments, molecular modeling, oxidation-reduction potentials, and spectral properties strongly indicate that the C. tepidum Fds are chimeras of both clostridial-type and chromatium-type Fds, suggesting that the two Fds are likely intermediates in the evolutional development of 2[4Fe-4S] clusters compared with the well described clostridial and chromatium types.
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Affiliation(s)
- K S Yoon
- Department of Microbiology, Plant Molecular Biology/Biotechnology Program, Protein Research Group, the Ohio State University, Columbus, Ohio 43210-1292, USA
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