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Jin M, Lu J, Chen Z, Nguyen SH, Mao L, Li J, Yuan Z, Guo J. Antidepressant fluoxetine induces multiple antibiotics resistance in Escherichia coli via ROS-mediated mutagenesis. ENVIRONMENT INTERNATIONAL 2018; 120:421-430. [PMID: 30125859 DOI: 10.1016/j.envint.2018.07.046] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/28/2018] [Accepted: 07/29/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Antibiotic resistance poses a great threat to global public health. Overuse of antibiotics is generally considered as the major factor contributing to it. However, little is known about whether non-antibiotic drugs could play potential roles in the emergence of antibiotic resistance. OBJECTIVE We aimed to investigate whether antidepressant fluoxetine induces multiple antibiotic resistances and reveal underlying mechanisms. METHODOLOGY Escherichia coli K12 was exposed to different concentrations of fluoxetine (0, 0.5, 5, 50 and 100 mg/L) and the resistant strains were isolated by plating on antibiotic containing plates. Resistant strains were randomly selected to determine the increase of minimum inhibition concentration (MIC) of multiple antibiotics. Genome-wide DNA sequencing was performed on cells cultured in lysogeny broth (LB) without any fluoxetine or antibiotics exposure. RNA sequencing and proteomic profiling of isolated mutants grown in LB with 100 mg/L fluoxetine were analyzed to reveal the underlying mechanisms. RESULTS Exposure of Escherichia coli to fluoxetine at 5-100 mg/L after repeated subculture in LB for 30 days promoted its mutation frequency resulting in increased resistance against the antibiotics chloramphenicol, amoxicillin and tetracycline. This increase was up to 5.0 × 107 fold in a dose-time pattern. Isolated mutants with resistance to one of these antibiotics also exhibited multiple resistances against fluoroquinolone, aminoglycoside, β-lactams, tetracycline and chloramphenicol. According to global transcriptional and proteomic analyses, the AcrAB-TolC pump together with the YadG/YadH transporter, a Tsx channel and the MdtEF-TolC pump have been triggered to export the antibiotics to the exterior of the cell. Whole-genome DNA analysis of the mutants further revealed that ROS-mediated mutagenesis (e.g., deletion, insertion, and substitution) of DNA-binding transcriptional regulators (e.g., marR, rob, sdiA, cytR and crp) to up-regulate the expression of efflux pumps, may further enhance the antibiotic efflux. CONCLUSIONS Our findings for the first time demonstrated that the exposure to antidepressant fluoxetine induces multiple antibiotic resistance in E. coli via the ROS-mediated mutagenesis.
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Affiliation(s)
- Min Jin
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Department of Environment and Health, Tianjin Institute of Environmental & Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Ji Lu
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Zhaoyu Chen
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Son Hoang Nguyen
- Institute for Molecular Bioscience, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
| | - Likai Mao
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Junwen Li
- Department of Environment and Health, Tianjin Institute of Environmental & Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China
| | - Zhiguo Yuan
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre (AWMC), University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
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Loi VV, Busche T, Tedin K, Bernhardt J, Wollenhaupt J, Huyen NTT, Weise C, Kalinowski J, Wahl MC, Fulde M, Antelmann H. Redox-Sensing Under Hypochlorite Stress and Infection Conditions by the Rrf2-Family Repressor HypR in Staphylococcus aureus. Antioxid Redox Signal 2018; 29:615-636. [PMID: 29237286 PMCID: PMC6067689 DOI: 10.1089/ars.2017.7354] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AIMS Staphylococcus aureus is a major human pathogen and has to cope with reactive oxygen and chlorine species (ROS, RCS) during infections, which requires efficient protection mechanisms to avoid destruction. Here, we have investigated the changes in the RNA-seq transcriptome by the strong oxidant sodium hypochlorite (NaOCl) in S. aureus USA300 to identify novel redox-sensing mechanisms that provide protection under infection conditions. RESULTS NaOCl stress caused an oxidative stress response in S. aureus as indicated by the induction of the PerR, QsrR, HrcA, and SigmaB regulons in the RNA-seq transcriptome. The hypR-merA (USA300HOU_0588-87) operon was most strongly upregulated under NaOCl stress, which encodes for the Rrf2-family regulator HypR and the pyridine nucleotide disulfide reductase MerA. We have characterized HypR as a novel redox-sensitive repressor that controls MerA expression and directly senses and responds to NaOCl and diamide stress via a thiol-based mechanism in S. aureus. Mutational analysis identified Cys33 and the conserved Cys99 as essential for NaOCl sensing, while Cys99 is also important for repressor activity of HypR in vivo. The redox-sensing mechanism of HypR involves Cys33-Cys99 intersubunit disulfide formation by NaOCl stress both in vitro and in vivo. Moreover, the HypR-controlled flavin disulfide reductase MerA was shown to protect S. aureus against NaOCl stress and increased survival in J774A.1 macrophage infection assays. Conclusion and Innovation: Here, we identified a new member of the widespread Rrf2 family as redox sensor of NaOCl stress in S. aureus that uses a thiol/disulfide switch to regulate defense mechanisms against the oxidative burst under infections in S. aureus. Antioxid. Redox Signal. 29, 615-636.
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Affiliation(s)
- Vu Van Loi
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany
| | - Tobias Busche
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany .,2 Center for Biotechnology, Bielefeld University , Bielefeld, Germany
| | - Karsten Tedin
- 3 Centre for Infection Medicine, Institute of Microbiology and Epizootics , Freie Universität Berlin, Berlin, Germany
| | - Jörg Bernhardt
- 4 Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald , Greifswald, Germany
| | - Jan Wollenhaupt
- 5 Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Nguyen Thi Thu Huyen
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany
| | - Christoph Weise
- 6 Institute of Chemistry and Biochemistry , Freie Universität Berlin, Berlin, Germany
| | - Jörn Kalinowski
- 2 Center for Biotechnology, Bielefeld University , Bielefeld, Germany
| | - Markus C Wahl
- 5 Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Marcus Fulde
- 3 Centre for Infection Medicine, Institute of Microbiology and Epizootics , Freie Universität Berlin, Berlin, Germany
| | - Haike Antelmann
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany
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Abstract
The abundance of oxidants and reductants must be balanced for an organism to thrive. Bacteria have evolved methods to prevent redox imbalances and to mitigate their deleterious consequences through the expression of detoxification enzymes, antioxidants, and systems to repair or degrade damaged proteins and DNA. Regulating these processes in response to redox changes requires sophisticated surveillance strategies ranging from metal chelation to direct sensing of toxic reactive oxygen species. In the case of bacterial pathogens, stress that threatens to disrupt redox homeostasis can derive from endogenous sources (produced by the bacteria) or exogenous sources (produced by the host). This minireview summarizes the sources of redox stress encountered during infection, the mechanisms by which bacterial pathogens diminish the damaging effects of redox stress, and the clever ways some organisms have evolved to thrive in the face of redox challenges during infection.
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Romsang A, Duang-Nkern J, Khemsom K, Wongsaroj L, Saninjuk K, Fuangthong M, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa ttcA encoding tRNA-thiolating protein requires an iron-sulfur cluster to participate in hydrogen peroxide-mediated stress protection and pathogenicity. Sci Rep 2018; 8:11882. [PMID: 30089777 PMCID: PMC6082896 DOI: 10.1038/s41598-018-30368-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/27/2018] [Indexed: 01/21/2023] Open
Abstract
During the translation process, transfer RNA (tRNA) carries amino acids to ribosomes for protein synthesis. Each codon of mRNA is recognized by a specific tRNA, and enzyme-catalysed modifications to tRNA regulate translation. TtcA is a unique tRNA-thiolating enzyme that requires an iron-sulfur ([Fe-S]) cluster to catalyse thiolation of tRNA. In this study, the physiological functions of a putative ttcA in Pseudomonas aeruginosa, an opportunistic human pathogen that causes serious problems in hospitals, were characterized. A P. aeruginosa ttcA-deleted mutant was constructed, and mutant cells were rendered hypersensitive to oxidative stress, such as hydrogen peroxide (H2O2) treatment. Catalase activity was lower in the ttcA mutant, suggesting that this gene plays a role in protecting against oxidative stress. Moreover, the ttcA mutant demonstrated attenuated virulence in a Drosophila melanogaster host model. Site-directed mutagenesis analysis revealed that the conserved cysteine motifs involved in [Fe-S] cluster ligation were required for TtcA function. Furthermore, ttcA expression increased upon H2O2 exposure, implying that enzyme levels are induced under stress conditions. Overall, the data suggest that P. aeruginosa ttcA plays a critical role in protecting against oxidative stress via catalase activity and is required for successful bacterial infection of the host.
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Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Khwannarin Khemsom
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Lampet Wongsaroj
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Mayuree Fuangthong
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand.,Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
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55
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Sarvan S, Butcher J, Stintzi A, Couture JF. Variation on a theme: investigating the structural repertoires used by ferric uptake regulators to control gene expression. Biometals 2018; 31:681-704. [DOI: 10.1007/s10534-018-0120-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 11/29/2022]
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Identification of a repressor and an activator of azoreductase gene expression in Pseudomonas putida and Xanthomonas oryzae. Biochem Biophys Res Commun 2018; 502:9-14. [DOI: 10.1016/j.bbrc.2018.05.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 05/16/2018] [Indexed: 11/18/2022]
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57
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Lim D, Kim KS, Jeong JH, Marques O, Kim HJ, Song M, Lee TH, Kim JI, Choi HS, Min JJ, Bumann D, Muckenthaler MU, Choy HE. The hepcidin-ferroportin axis controls the iron content of Salmonella-containing vacuoles in macrophages. Nat Commun 2018; 9:2091. [PMID: 29844422 PMCID: PMC5974375 DOI: 10.1038/s41467-018-04446-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 04/27/2018] [Indexed: 02/06/2023] Open
Abstract
Macrophages release iron into the bloodstream via a membrane-bound iron export protein, ferroportin (FPN). The hepatic iron-regulatory hormone hepcidin controls FPN internalization and degradation in response to bacterial infection. Salmonella typhimurium can invade macrophages and proliferate in the Salmonella-containing vacuole (SCV). Hepcidin is reported to increase the mortality of Salmonella-infected animals by increasing the bacterial load in macrophages. Here we assess the iron levels and find that hepcidin increases iron content in the cytosol but decreases it in the SCV through FPN on the SCV membrane. Loss-of-FPN from the SCV via the action of hepcidin impairs the generation of bactericidal reactive oxygen species (ROS) as the iron content decreases. We conclude that FPN is required to provide sufficient iron to the SCV, where iron serves as a cofactor for the generation of antimicrobial ROS rather than as a nutrient for Salmonella. The effects of iron on vacuole-resident Salmonella in macrophages are unclear. Here the authors show that the bacteria are not subject to nutritional inhibition by iron deprivation, but that iron depletion in the vacuole, via the hepcidin-ferroportin axis, inhibits the bactericidal effect of oxidative burst.
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Affiliation(s)
- Daejin Lim
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea
| | - Kwang Soo Kim
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea
| | - Jae-Ho Jeong
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea
| | - Oriana Marques
- Department of Pediatric Hematology, Oncology and Immunology - University of Heidelberg, Im Neuenheimer Feld 350, Heidelberg, D-69120, Germany.,Molecular Medicine Partnership Unit, Heidelberg, D-69120, Germany.,Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, D-69120, Germany
| | - Hyun-Ju Kim
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea
| | - Miryoung Song
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea
| | - Tae-Hoon Lee
- Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea.,Department of Biochemistry, Dental Science Research Institute, School of Dentistry, Chonnam National University and Korea mouse phenotype center (KMPC), Gwangju, 61186, Republic of Korea
| | - Jae Il Kim
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.,AnyGen, Gwangju Technopark, Gwangju, 61008, Republic of Korea
| | - Hueng-Sik Choi
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Jung-Joon Min
- Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea.,Department of Nuclear Medicine, Chonnam National University Medical School, Gwangju, 61469, Republic of Korea
| | - Dirk Bumann
- Focal Area Infection Biology, University of Basel, Basel, CH-4056, Switzerland
| | - Martina U Muckenthaler
- Department of Pediatric Hematology, Oncology and Immunology - University of Heidelberg, Im Neuenheimer Feld 350, Heidelberg, D-69120, Germany.,Molecular Medicine Partnership Unit, Heidelberg, D-69120, Germany.,Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, D-69120, Germany
| | - Hyon E Choy
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea. .,Department of Molecular Medicine (BK21plus), Chonnam National University Graduate School, Gwangju, 61468, Republic of Korea.
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58
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Demidchik V. ROS-Activated Ion Channels in Plants: Biophysical Characteristics, Physiological Functions and Molecular Nature. Int J Mol Sci 2018; 19:E1263. [PMID: 29690632 PMCID: PMC5979493 DOI: 10.3390/ijms19041263] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 12/16/2022] Open
Abstract
Ion channels activated by reactive oxygen species (ROS) have been found in the plasma membrane of charophyte Nitella flixilis, dicotyledon Arabidopsis thaliana, Pyrus pyrifolia and Pisum sativum, and the monocotyledon Lilium longiflorum. Their activities have been reported in charophyte giant internodes, root trichoblasts and atrichoblasts, pollen tubes, and guard cells. Hydrogen peroxide and hydroxyl radicals are major activating species for these channels. Plant ROS-activated ion channels include inwardly-rectifying, outwardly-rectifying, and voltage-independent groups. The inwardly-rectifying ROS-activated ion channels mediate Ca2+-influx for growth and development in roots and pollen tubes. The outwardly-rectifying group facilitates K⁺ efflux for the regulation of osmotic pressure in guard cells, induction of programmed cell death, and autophagy in roots. The voltage-independent group mediates both Ca2+ influx and K⁺ efflux. Most studies suggest that ROS-activated channels are non-selective cation channels. Single-channel studies revealed activation of 14.5-pS Ca2+ influx and 16-pS K⁺ efflux unitary conductances in response to ROS. The molecular nature of ROS-activated Ca2+ influx channels remains poorly understood, although annexins and cyclic nucleotide-gated channels have been proposed for this role. The ROS-activated K⁺ channels have recently been identified as products of Stellar K⁺ Outward Rectifier (SKOR) and Guard cell Outwardly Rectifying K⁺ channel (GORK) genes.
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Affiliation(s)
- Vadim Demidchik
- Department of Horticulture, School of Food Science and Engineering, Foshan University, Foshan 528000, China.
- Department of Plant Cell Biology and Bioengineering, Biological Faculty, Belarusian State University, 4 Independence Avenue, 220030 Minsk, Belarus.
- Russian Academy of Sciences, Komarov Botanical Institute, 2 Professora Popova Street, 197376 St. Petersburg, Russia.
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Lee HN, Ji CJ, Lee HH, Park J, Seo YS, Lee JW, Oh JI. Roles of three FurA paralogs in the regulation of genes pertaining to peroxide defense in Mycobacterium smegmatis mc 2 155. Mol Microbiol 2018; 108:661-682. [PMID: 29569300 DOI: 10.1111/mmi.13956] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2018] [Indexed: 11/28/2022]
Abstract
Mycobacterium smegmatis mc2 155 has three genes (MSMEG_6383, furA1; MSMEG_3460, furA2; MSMEG_6253, furA3) encoding FurA (ferric-uptake regulator A) paralogs. Three FurA paralogs in M. smegmatis are functionally redundant and negatively regulate expression of a subset of genes involved in peroxide detoxification such as ahpC, katG1 and katG2, as well as their own genes. The FurA paralogs sense H2 O2 via metal-catalyzed His oxidation (MCHO) in the same way as PerR. The propensity of FurA2 and FurA3 for MCHO is greater than that of FurA1. The three furA genes are transcribed into leaderless mRNAs lacking the Shine-Dalgarno (SD) sequence. FurA1 and FurA3 have the quaternary structure of homodimers like most Fur homologs, whereas FurA2 occurs as a monomer. The monomeric structure of FurA2 is determined by the C-terminal region of its dimerization domain. FurA2 monomers appear to cooperatively bind to the FurA-binding site with an inverted repeat configuration and have a broader binding specificity for the target DNA than dimeric FurA1 and FurA3. Comparative transcriptomic analysis revealed that the FurA paralogs do not regulate genes related to iron homeostasis in M. smegmatis, and that expression of SigF-regulated genes is significantly decreased in a furA triple mutant relative to the wild-type strain of M. smegmatis.
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Affiliation(s)
- Ha-Na Lee
- Department of Microbiology, Pusan National University, Busan, 46241, Korea
| | - Chang-Jun Ji
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Korea
| | - Hyun-Hee Lee
- Department of Microbiology, Pusan National University, Busan, 46241, Korea
| | - Jungwook Park
- Department of Microbiology, Pusan National University, Busan, 46241, Korea
| | - Young-Su Seo
- Department of Microbiology, Pusan National University, Busan, 46241, Korea
| | - Jin-Won Lee
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Korea
| | - Jeong-Il Oh
- Department of Microbiology, Pusan National University, Busan, 46241, Korea
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60
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Petkowski JJ, Bains W, Seager S. Natural Products Containing a Nitrogen-Sulfur Bond. JOURNAL OF NATURAL PRODUCTS 2018; 81:423-446. [PMID: 29364663 DOI: 10.1021/acs.jnatprod.7b00921] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Only about 100 natural products are known to contain a nitrogen-sulfur (N-S) bond. This review thoroughly categorizes N-S bond-containing compounds by structural class. Information on biological source, biological activity, and biosynthesis is included, if known. We also review the role of N-S bond functional groups as post-translational modifications of amino acids in proteins and peptides, emphasizing their role in the metabolism of the cell.
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Affiliation(s)
- Janusz J Petkowski
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - William Bains
- Rufus Scientific , 37 The Moor, Melbourn, Royston, Herts SG8 6ED, U.K
| | - Sara Seager
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Department of Physics, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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61
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Demidchik V, Tyutereva EV, Voitsekhovskaja OV. The role of ion disequilibrium in induction of root cell death and autophagy by environmental stresses. FUNCTIONAL PLANT BIOLOGY : FPB 2018; 45:28-46. [PMID: 32291019 DOI: 10.1071/fp16380] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/09/2016] [Indexed: 05/26/2023]
Abstract
Environmental stresses such as salinity, drought, oxidants, heavy metals, hypoxia, extreme temperatures and others can induce autophagy and necrosis-type programmed cell death (PCD) in plant roots. These reactions are accompanied by the generation of reactive oxygen species (ROS) and ion disequilibrium, which is induced by electrolyte/K+ leakage through ROS-activated ion channels, such as the outwardly-rectifying K+ channel GORK and non-selective cation channels. Here, we discuss mechanisms of the stress-induced ion disequilibrium and relate it with ROS generation and onset of morphological, biochemical and genetic symptoms of autophagy and PCD in roots. Based on our own data and that in the literature, we propose a hypothesis on the induction of autophagy and PCD in roots by loss of cytosolic K+. To support this, we present data showing that in conditions of salt stress-induced autophagy, gork1-1 plants lacking root K+ efflux channel have fewer autophagosomes compared with the wild type. Overall, literature analyses and presented data strongly suggest that stress-induced root autophagy and PCD are controlled by the level of cytosolic potassium and ROS.
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Affiliation(s)
- Vadim Demidchik
- Laboratory of Plant Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, ul. Professora Popova 2, 197376St Petersburg, Russia
| | - Elena V Tyutereva
- Laboratory of Plant Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, ul. Professora Popova 2, 197376St Petersburg, Russia
| | - Olga V Voitsekhovskaja
- Laboratory of Plant Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, ul. Professora Popova 2, 197376St Petersburg, Russia
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Kebouchi M, Saul F, Taher R, Landier A, Beaudeau B, Dubrac S, Weber P, Haouz A, Picardeau M, Benaroudj N. Structure and function of the Leptospira interrogans peroxide stress regulator (PerR), an atypical PerR devoid of a structural metal-binding site. J Biol Chem 2017; 293:497-509. [PMID: 29146596 DOI: 10.1074/jbc.m117.804443] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/10/2017] [Indexed: 01/24/2023] Open
Abstract
Peroxide sensing is essential for bacterial survival during aerobic metabolism and host infection. Peroxide stress regulators (PerRs) are homodimeric transcriptional repressors with each monomer typically containing both structural and regulatory metal-binding sites. PerR binding to gene promoters is controlled by the presence of iron in the regulatory site, and iron-catalyzed oxidation of PerR by H2O2 leads to the dissociation of PerR from DNA. In addition to a regulatory metal, most PerRs require a structural metal for proper dimeric assembly. We present here a structural and functional characterization of the PerR from the pathogenic spirochete Leptospira interrogans, a rare example of PerR lacking a structural metal-binding site. In vivo studies showed that the leptospiral PerR belongs to the peroxide stimulon in pathogenic species and is involved in controlling resistance to peroxide. Moreover, a perR mutant had decreased fitness in other host-related stress conditions, including at 37 °C or in the presence of superoxide anion. In vitro, leptospiral PerR could bind to the perR promoter region in a metal-dependent manner. The crystal structure of the leptospiral PerR revealed an asymmetric homodimer, with one monomer displaying complete regulatory metal coordination in the characteristic caliper-like DNA-binding conformation and the second monomer exhibiting disrupted regulatory metal coordination in an open non-DNA-binding conformation. This structure showed that leptospiral PerR assembles into a dimer in which a metal-induced conformational switch can occur independently in the two monomers. Our study demonstrates that structural metal binding is not compulsory for PerR dimeric assembly and for regulating peroxide stress.
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Affiliation(s)
| | | | | | | | | | - Sarah Dubrac
- Unité de Biologie des Bactéries Pathogènes à Gram Positif, Institut Pasteur, F-75015 Paris, France
| | | | - Ahmed Haouz
- Plate-forme de Cristallographie, CNRS UMR 3528, and
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Do H, Makthal N, VanderWal AR, Rettel M, Savitski MM, Peschek N, Papenfort K, Olsen RJ, Musser JM, Kumaraswami M. Leaderless secreted peptide signaling molecule alters global gene expression and increases virulence of a human bacterial pathogen. Proc Natl Acad Sci U S A 2017; 114:E8498-E8507. [PMID: 28923955 PMCID: PMC5635878 DOI: 10.1073/pnas.1705972114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Successful pathogens use complex signaling mechanisms to monitor their environment and reprogram global gene expression during specific stages of infection. Group A Streptococcus (GAS) is a major human pathogen that causes significant disease burden worldwide. A secreted cysteine protease known as streptococcal pyrogenic exotoxin B (SpeB) is a key virulence factor that is produced abundantly during infection and is critical for GAS pathogenesis. Although identified nearly a century ago, the molecular basis for growth phase control of speB gene expression remains unknown. We have discovered that GAS uses a previously unknown peptide-mediated intercellular signaling system to control SpeB production, alter global gene expression, and enhance virulence. GAS produces an eight-amino acid leaderless peptide [SpeB-inducing peptide (SIP)] during high cell density and uses the secreted peptide for cell-to-cell signaling to induce population-wide speB expression. The SIP signaling pathway includes peptide secretion, reimportation into the cytosol, and interaction with the intracellular global gene regulator Regulator of Protease B (RopB), resulting in SIP-dependent modulation of DNA binding and regulatory activity of RopB. Notably, SIP signaling causes differential expression of ∼14% of GAS core genes. Several genes that encode toxins and other virulence genes that enhance pathogen dissemination and infection are significantly up-regulated. Using three mouse infection models, we show that the SIP signaling pathway is active during infection and contributes significantly to GAS pathogenesis at multiple host anatomic sites. Together, our results delineate the molecular mechanisms involved in a previously undescribed virulence regulatory pathway of an important human pathogen and suggest new therapeutic strategies.
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Affiliation(s)
- Hackwon Do
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
| | - Nishanth Makthal
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
| | - Arica R VanderWal
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
| | - Mandy Rettel
- Genome Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Mikhail M Savitski
- Genome Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nikolai Peschek
- Munich Center for Integrated Protein Science, Department of Microbiology, Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
| | - Kai Papenfort
- Munich Center for Integrated Protein Science, Department of Microbiology, Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
| | - Randall J Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10021
| | - James M Musser
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10021
| | - Muthiah Kumaraswami
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030;
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
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64
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Dudte SC, Hinnebusch BJ, Shannon JG. Characterization of Yersinia pestis Interactions with Human Neutrophils In vitro. Front Cell Infect Microbiol 2017; 7:358. [PMID: 28848716 PMCID: PMC5552669 DOI: 10.3389/fcimb.2017.00358] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/25/2017] [Indexed: 12/16/2022] Open
Abstract
Yersinia pestis is a gram-negative, zoonotic, bacterial pathogen, and the causative agent of plague. The bubonic form of plague occurs subsequent to deposition of bacteria in the skin by the bite of an infected flea. Neutrophils are recruited to the site of infection within the first few hours and interactions between neutrophils and Y. pestis have been demonstrated in vivo. In contrast to macrophages, neutrophils have been considered non-permissive to Y. pestis intracellular survival. Several studies have shown killing of the vast majority of Y. pestis ingested by human neutrophils. However, survival of 10–15% of Y. pestis after phagocytosis by neutrophils is consistently observed. Furthermore, these surviving bacteria eventually replicate within and escape from the neutrophils. We set out to further characterize the interactions between Y. pestis and human neutrophils by (1) determining the effects of known Y. pestis virulence factors on bacterial survival after uptake by neutrophils, (2) examining the mechanisms employed by the neutrophil to kill the majority of intracellular Y. pestis, (3) determining the activation phenotype of Y. pestis-infected neutrophils, and (4) characterizing the Y. pestis-containing phagosome in neutrophils. We infected human neutrophils in vitro with Y. pestis and assayed bacterial survival and uptake. Deletion of the caf1 gene responsible for F1 capsule production resulted in significantly increased uptake of Y. pestis. Surprisingly, while the two-component regulator PhoPQ system is important for survival of Y. pestis within neutrophils, pre-induction of this system prior to infection did not increase bacterial survival. We used an IPTG-inducible mCherry construct to distinguish viable from non-viable intracellular bacteria and determined the association of the Y. pestis-containing phagosome with neutrophil NADPH-oxidase and markers of primary, secondary and tertiary granules. Additionally, we show that inhibition of reactive oxygen species (ROS) production or Src family kinases increased survival of intracellular bacteria indicating that both ROS and granule-phagosome fusion contribute to neutrophil killing of Y. pestis. The data presented here further our understanding of the Y. pestis neutrophil interactions and suggest the existence of still unknown virulence factors involved in Y. pestis survival within neutrophils.
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Affiliation(s)
- Sophia C Dudte
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of HealthHamilton, MT, United States
| | - B Joseph Hinnebusch
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of HealthHamilton, MT, United States
| | - Jeffrey G Shannon
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of HealthHamilton, MT, United States
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Kashef N, Hamblin MR. Can microbial cells develop resistance to oxidative stress in antimicrobial photodynamic inactivation? Drug Resist Updat 2017; 31:31-42. [PMID: 28867242 DOI: 10.1016/j.drup.2017.07.003] [Citation(s) in RCA: 197] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/28/2017] [Accepted: 07/13/2017] [Indexed: 01/08/2023]
Abstract
Infections have been a major cause of disease throughout the history of humans on earth. With the introduction of antibiotics, it was thought that infections had been conquered. However, bacteria have been able to develop resistance to antibiotics at an exponentially increasing rate. The growing threat from multi-drug resistant organisms calls for intensive action to prevent the emergence of totally resistant and untreatable infections. Novel, non-invasive, non-antibiotic strategies are needed that act more efficiently and faster than current antibiotics. One promising alternative is antimicrobial photodynamic inactivation (APDI), an approach that produces reactive oxygen species when dyes and light are combined. So far, it has been questionable if bacteria can develop resistance against APDI. This review paper gives an overview of recent studies concerning the susceptibility of bacteria towards oxidative stress, and suggests possible mechanisms of the development of APDI-resistance that should at least be addressed. Some ways to potentiate APDI and also to overcome future resistance are suggested.
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Affiliation(s)
- Nasim Kashef
- Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran; Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA, 02115, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, 02139, USA.
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66
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Global Transcriptional Response to Organic Hydroperoxide and the Role of OhrR in the Control of Virulence Traits in Chromobacterium violaceum. Infect Immun 2017; 85:IAI.00017-17. [PMID: 28507067 DOI: 10.1128/iai.00017-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/04/2017] [Indexed: 11/20/2022] Open
Abstract
A major pathway for the detoxification of organic hydroperoxides, such as cumene hydroperoxide (CHP), involves the MarR family transcriptional regulator OhrR and the peroxidase OhrA. However, the effect of these peroxides on the global transcriptome and the contribution of the OhrA/OhrR system to bacterial virulence remain poorly explored. Here, we analyzed the transcriptome profiles of Chromobacterium violaceum exposed to CHP and after the deletion of ohrR, and we show that OhrR controls the virulence of this human opportunistic pathogen. DNA microarray and Northern blot analyses of CHP-treated cells revealed the upregulation of genes related to the detoxification of peroxides (antioxidant enzymes and thiol-reducing systems), the degradation of the aromatic moiety of CHP (oxygenases), and protection against other secondary stresses (DNA repair, heat shock, iron limitation, and nitrogen starvation responses). Furthermore, we identified two upregulated genes (ohrA and a putative diguanylate cyclase with a GGDEF domain for cyclic di-GMP [c-di-GMP] synthesis) and three downregulated genes (hemolysin, chitinase, and collagenase) in the ohrR mutant by transcriptome analysis. Importantly, we show that OhrR directly repressed the expression of the putative diguanylate cyclase. Using a mouse infection model, we demonstrate that the ohrR mutant was attenuated for virulence and showed a decreased bacterial burden in the liver. Moreover, an ohrR-diguanylate cyclase double mutant displayed the same virulence as the wild-type strain. In conclusion, we have defined the transcriptional response to CHP, identified potential virulence factors such as diguanylate cyclase as members of the OhrR regulon, and shown that C. violaceum uses the transcriptional regulator OhrR to modulate its virulence.
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67
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Abstract
Organic hydroperoxide reductase regulator (OhrR) in bacteria is a sensor for organic hydroperoxide stress and a transcriptional regulator for the enzyme organic hydroperoxide reductase (Ohr). In this study we investigated, using a GFP reporter system, whether Mycobacterium smegmatis OhrR has the ability to sense and respond to intracellular organic hydroperoxide stress. It was observed that M. smegmatis strains bearing the pohr-gfpuv fusion construct were able to express GFP only in the absence of an intact ohrR gene, but not in its presence. However, GFP expression in the strain bearing pohr-gfpuv with an intact ohrR gene could be induced by organic hydroperoxides in vitro and in the intracellular environment upon ingestion of the bacteria by macrophages; indicating that OhrR responds not only to in vitro but also to intracellular organic hydroperoxide stress. Further, the intracellular expression of pohr driven GFP in this strain could be abolished by replacing the intact ohrR gene with a mutant ohrR gene modified for N-terminal Cysteine (Cys) residue, suggesting that OhrR senses intracellular organic hydroperoxides through Cys residue. This is the first report demonstrating the ability of OhrR to sense intracellular organic hydroperoxides.
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68
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Villa JK, Amador P, Janovsky J, Bhuyan A, Saldanha R, Lamkin TJ, Contreras LM. A Genome-Wide Search for Ionizing-Radiation-Responsive Elements in Deinococcus radiodurans Reveals a Regulatory Role for the DNA Gyrase Subunit A Gene's 5' Untranslated Region in the Radiation and Desiccation Response. Appl Environ Microbiol 2017; 83:e00039-17. [PMID: 28411225 PMCID: PMC5452802 DOI: 10.1128/aem.00039-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 04/07/2017] [Indexed: 12/19/2022] Open
Abstract
Tight regulation of gene expression is important for the survival of Deinococcus radiodurans, a model bacterium of extreme stress resistance. Few studies have examined the use of regulatory RNAs as a possible contributing mechanism to ionizing radiation (IR) resistance, despite their proffered efficient and dynamic gene expression regulation under IR stress. This work presents a transcriptome-based approach for the identification of stress-responsive regulatory 5' untranslated region (5'-UTR) elements in D. radiodurans R1 that can be broadly applied to other bacteria. Using this platform and an in vivo fluorescence screen, we uncovered the presence of a radiation-responsive regulatory motif in the 5' UTR of the DNA gyrase subunit A gene. Additional screens under H2O2-induced oxidative stress revealed the specificity of the response of this element to IR stress. Further examination of the sequence revealed a regulatory motif of the radiation and desiccation response (RDR) in the 5' UTR that is necessary for the recovery of D. radiodurans from high doses of IR. Furthermore, we suggest that it is the preservation of predicted RNA structure, in addition to DNA sequence consensus of the motif, that permits this important regulatory ability.IMPORTANCEDeinococcus radiodurans is an extremely stress-resistant bacterium capable of tolerating up to 3,000 times more ionizing radiation than human cells. As an integral part of the stress response mechanism of this organism, we suspect that it maintains stringent control of gene expression. However, understanding of its regulatory pathways remains incomplete to date. Untranslated RNA elements have been demonstrated to play crucial roles in gene regulation throughout bacteria. In this work, we focus on searching for and characterizing responsive RNA elements under radiation stress and propose that multiple levels of gene regulation work simultaneously to enable this organism to efficiently recover from exposure to ionizing radiation. The model we propose serves as a generic template to investigate similar mechanisms of gene regulation under stress that have likely evolved in other bacterial species.
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Affiliation(s)
- Jordan K Villa
- Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Paul Amador
- Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Justin Janovsky
- Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Arijit Bhuyan
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas,USA
| | | | - Thomas J Lamkin
- Air Force Research Laboratory/XPRA Wright-Patterson AFB, Ohio, USA
| | - Lydia M Contreras
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas,USA
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69
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Iron Efflux by PmtA Is Critical for Oxidative Stress Resistance and Contributes Significantly to Group A Streptococcus Virulence. Infect Immun 2017; 85:IAI.00091-17. [PMID: 28348051 DOI: 10.1128/iai.00091-17] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/20/2017] [Indexed: 12/20/2022] Open
Abstract
Group A Streptococcus (GAS) is a human-only pathogen that causes a spectrum of disease conditions. Given its survival in inflamed lesions, the ability to sense and overcome oxidative stress is critical for GAS pathogenesis. PerR senses oxidative stress and coordinates the regulation of genes involved in GAS antioxidant defenses. In this study, we investigated the role of PerR-controlled metal transporter A (PmtA) in GAS pathogenesis. Previously, PmtA was implicated in GAS antioxidant defenses and suggested to protect against zinc toxicity. Here, we report that PmtA is a P1B4-type ATPase that functions as an Fe(II) exporter and aids GAS defenses against iron intoxication and oxidative stress. The expression of pmtA is specifically induced by excess iron, and this induction requires PerR. Furthermore, a pmtA mutant exhibited increased sensitivity to iron toxicity and oxidative stress due to an elevated intracellular accumulation of iron. RNA-sequencing analysis revealed that GAS undergoes significant alterations in gene expression to adapt to iron toxicity. Finally, using two mouse models of invasive infection, we demonstrated that iron efflux by PmtA is critical for bacterial survival during infection and GAS virulence. Together, these data demonstrate that PmtA is a key component of GAS antioxidant defenses and contributes significantly to GAS virulence.
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70
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Núñez-Díaz JA, Fumanal M, Viguera E, Moriñigo MA, Balebona MC. Use of in vivo induced technology to identify antigens expressed by Photobacterium damselae subsp. piscicida during infection of Senegalese sole (Solea senegalensis). FISH & SHELLFISH IMMUNOLOGY 2017; 64:446-456. [PMID: 28359946 DOI: 10.1016/j.fsi.2017.03.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/22/2017] [Accepted: 03/26/2017] [Indexed: 06/07/2023]
Abstract
Photobacterium damselae subsp. piscicida (Phdp), the causative agent of photobacteriosis, is an important pathogen in marine aquaculture that affects many different fish species worldwide, including Solea senegalensis, an important fish species for aquaculture in the south of Europe. Bacteria express different repertoires of proteins in response to environmental conditions and when invading a host, sense in vivo environment and adapt by changing the expression of specific proteins. In the case of pathogens, identification of genes with up-regulated expression in vivo compared to in vitro conditions might give an insight into the genes relevant to the bacterial virulence. In the present work, in vivo induced antigen technology (IVIAT) has been used to search for Phdp genes only expressed or up-regulated in infected S. senegalensis. An expression library from Phdp was assayed against pooled sera from convalescent S. senegalensis specimens and 18 clones were positive, indicating that proteins encoded are expressed by Phdp during S. senegalensis infection and are immunogenic for this fish species. In addition, five proteins were reactive against adsorbed sera, indicating their in vivo induced character. Inosine-5'-monophosphate dehydrogenase, serine hydroxy methyltransferase and alanyl-tRNA synthethase, involved in aminoacid and nucleotide metabolism, the protein with antioxidant activity alkyl hydroperoxide reductase and a non-ribosomal peptide synthetase responsible for the synthesis of the siderophore piscibactin have been identified as antigens induced in Phdp during S. senegalensis infection. Proteins induced during in vivo growth of Phdp represent promising targets for the development of novel antimicrobial or prophylactic agents in the treatment and prevention of photobacteriosis.
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Affiliation(s)
- J A Núñez-Díaz
- Universidad de Málaga, Departamento de Microbiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - M Fumanal
- Universidad de Málaga, Departamento de Microbiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - E Viguera
- Universidad de Málaga, Área de Genética, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - M A Moriñigo
- Universidad de Málaga, Departamento de Microbiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - M C Balebona
- Universidad de Málaga, Departamento de Microbiología, Campus de Teatinos s/n, 29071 Málaga, Spain.
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71
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Undabarrena A, Ugalde JA, Seeger M, Cámara B. -Genomic data mining of the marine actinobacteria Streptomyces sp. H-KF8 unveils insights into multi-stress related genes and metabolic pathways involved in antimicrobial synthesis. PeerJ 2017; 5:e2912. [PMID: 28229018 PMCID: PMC5312570 DOI: 10.7717/peerj.2912] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/14/2016] [Indexed: 12/25/2022] Open
Abstract
Streptomyces sp. H-KF8 is an actinobacterial strain isolated from marine sediments of a Chilean Patagonian fjord. Morphological characterization together with antibacterial activity was assessed in various culture media, revealing a carbon-source dependent activity mainly against Gram-positive bacteria (S. aureus and L. monocytogenes). Genome mining of this antibacterial-producing bacterium revealed the presence of 26 biosynthetic gene clusters (BGCs) for secondary metabolites, where among them, 81% have low similarities with known BGCs. In addition, a genomic search in Streptomyces sp. H-KF8 unveiled the presence of a wide variety of genetic determinants related to heavy metal resistance (49 genes), oxidative stress (69 genes) and antibiotic resistance (97 genes). This study revealed that the marine-derived Streptomyces sp. H-KF8 bacterium has the capability to tolerate a diverse set of heavy metals such as copper, cobalt, mercury, chromate and nickel; as well as the highly toxic tellurite, a feature first time described for Streptomyces. In addition, Streptomyces sp. H-KF8 possesses a major resistance towards oxidative stress, in comparison to the soil reference strain Streptomyces violaceoruber A3(2). Moreover, Streptomyces sp. H-KF8 showed resistance to 88% of the antibiotics tested, indicating overall, a strong response to several abiotic stressors. The combination of these biological traits confirms the metabolic versatility of Streptomyces sp. H-KF8, a genetically well-prepared microorganism with the ability to confront the dynamics of the fjord-unique marine environment.
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Affiliation(s)
- Agustina Undabarrena
- Departmento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María , Valparaiso , Chile
| | - Juan A Ugalde
- Centro de Genética y Genómica, Facultad de Medicina Clinica Alemana, Universidad del Desarrollo , Santiago , Chile
| | - Michael Seeger
- Departmento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María , Valparaiso , Chile
| | - Beatriz Cámara
- Departmento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María , Valparaiso , Chile
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Loss of OxyR reduces efficacy of oxygen respiration in Shewanella oneidensis. Sci Rep 2017; 7:42609. [PMID: 28195212 PMCID: PMC5307378 DOI: 10.1038/srep42609] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/11/2017] [Indexed: 02/02/2023] Open
Abstract
In many bacteria, OxyR is the major regulator controlling cellular response to H2O2. A common phenotype resulting from OxyR loss is reduced growth rate, but the underlying mechanism is unknown. We demonstrated in Shewanella oneidensis, an important research model for applied and environmental microbes, that the defect is primarily due to an electron shortage to major terminal oxidase cytochrome cbb3. The loss of OxyR leads to enhanced production of electron carriers that compete for electrons against cytochrome cbb3, cytochrome bd in particular. We further showed that the oxyR mutation also results in increased production of menaquinone, an additional means to lessen electrons to cytochrome cbb3. Although regulation of OxyR on these biological processes appears to be indirect, these data indicate that the regulator plays a previously underappreciated role in mediating respiration.
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73
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Boonma S, Romsang A, Duang-Nkern J, Atichartpongkul S, Trinachartvanit W, Vattanaviboon P, Mongkolsuk S. The FinR-regulated essential gene fprA, encoding ferredoxin NADP+ reductase: Roles in superoxide-mediated stress protection and virulence of Pseudomonas aeruginosa. PLoS One 2017; 12:e0172071. [PMID: 28187184 PMCID: PMC5302815 DOI: 10.1371/journal.pone.0172071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/30/2017] [Indexed: 11/23/2022] Open
Abstract
Pseudomonas aeruginosa has two genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. We show here that P. aeruginosa fprA is an essential gene. However, the ΔfprA mutant could only be successfully constructed in PAO1 strains containing an extra copy of fprA on a mini-Tn7 vector integrated into the chromosome or carrying it on a temperature-sensitive plasmid. The strain containing an extra copy of the ferredoxin gene (fdx1) could suppress the essentiality of FprA. Other ferredoxin genes could not suppress the requirement for FprA, suggesting that Fdx1 mediates the essentiality of FprA. The expression of fprA was highly induced in response to treatments with a superoxide generator, paraquat, or sodium hypochlorite (NaOCl). The induction of fprA by these treatments depended on FinR, a LysR-family transcription regulator. In vivo and in vitro analysis suggested that oxidized FinR acted as a transcriptional activator of fprA expression by binding to its regulatory box, located 20 bases upstream of the fprA -35 promoter motif. This location of the FinR box also placed it between the -35 and -10 motifs of the finR promoter, where the reduced regulator functions as a repressor. Under uninduced conditions, binding of FinR repressed its own transcription but had no effect on fprA expression. Exposure to paraquat or NaOCl converted FinR to a transcriptional activator, leading to the expression of both fprA and finR. The ΔfinR mutant showed an increased paraquat sensitivity phenotype and attenuated virulence in the Drosophila melanogaster host model. These phenotypes could be complemented by high expression of fprA, indicating that the observed phenotypes of the ΔfinR mutant arose from the inability to up-regulate fprA expression. In addition, increased expression of fprB was unable to rescue essentiality of fprA or the superoxide-sensitive phenotype of the ΔfinR mutant, suggesting distinct mechanisms of the FprA and FprB enzymes.
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Affiliation(s)
- Siriwan Boonma
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | | | | | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.,Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
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74
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Liu G, Liu X, Xu H, Liu X, Zhou H, Huang Z, Gan J, Chen H, Lan L, Yang CG. Structural Insights into the Redox-Sensing Mechanism of MarR-Type Regulator AbfR. J Am Chem Soc 2017; 139:1598-1608. [PMID: 28086264 DOI: 10.1021/jacs.6b11438] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As a master redox-sensing MarR-family transcriptional regulator, AbfR participates in oxidative stress responses and virulence regulations in Staphylococcus epidermidis. Here, we present structural insights into the DNA-binding mechanism of AbfR in different oxidation states by determining the X-ray crystal structures of a reduced-AbfR/DNA complex, an overoxidized (Cys13-SO2H and Cys13-SO3H) AbfR/DNA, and 2-disulfide cross-linked AbfR dimer. Together with biochemical analyses, our results suggest that the redox regulation of AbfR-sensing displays two novel features: (i) the reversible disulfide modification, but not the irreversible overoxidation, significantly abolishes the DNA-binding ability of the AbfR repressor; (ii) either 1-disulfide cross-linked or 2-disulfide cross-linked AbfR dimer is biologically significant. The overoxidized species of AbfR, resembling the reduced AbfR in conformation and retaining the DNA-binding ability, does not exist in biologically significant concentrations, however. The 1-disulfide cross-linked modification endows AbfR with significantly weakened capability for DNA-binding. The 2-disulfide cross-linked AbfR adopts a very "open" conformation that is incompatible with DNA-binding. Overall, the concise oxidation chemistry of the redox-active cysteine allows AbfR to sense and respond to oxidative stress correctly and efficiently.
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Affiliation(s)
- Guijie Liu
- Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China.,University of Chinese Academy of Sciences , Beijing 100049, China
| | - Xing Liu
- Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China.,CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Hongjiao Xu
- Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China.,University of Chinese Academy of Sciences , Beijing 100049, China
| | - Xichun Liu
- Coordination Chemistry Institute and State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China
| | - Hu Zhou
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Zhen Huang
- Department of Chemistry, Georgia State University , Atlanta, Georgia 30303, United States
| | - Jianhua Gan
- School of Life Sciences, Fudan University , Shanghai 200433, China
| | - Hao Chen
- Coordination Chemistry Institute and State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China
| | - Lefu Lan
- Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
| | - Cai-Guang Yang
- Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203, China
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Rittiroongrad S, Charoenlap N, Giengkam S, Vattanaviboon P, Mongkolsuk S. Agrobacterium tumefaciens estC, Encoding an Enzyme Containing Esterase Activity, Is Regulated by EstR, a Regulator in the MarR Family. PLoS One 2016; 11:e0168791. [PMID: 28036400 PMCID: PMC5201249 DOI: 10.1371/journal.pone.0168791] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/06/2016] [Indexed: 11/18/2022] Open
Abstract
Analysis of the A. tumefaciens genome revealed estC, which encodes an esterase located next to its transcriptional regulator estR, a regulator of esterase in the MarR family. Inactivation of estC results in a small increase in the resistance to organic hydroperoxides, whereas a high level of expression of estC from an expression vector leads to a reduction in the resistance to organic hydroperoxides and menadione. The estC gene is transcribed divergently from its regulator, estR. Expression analysis showed that only high concentrations of cumene hydroperoxide (CHP, 1 mM) induced expression of both genes in an EstR-dependent manner. The EstR protein acts as a CHP sensor and a transcriptional repressor of both genes. EstR specifically binds to the operator sites OI and OII overlapping the promoter elements of estC and estR. This binding is responsible for transcription repression of both genes. Exposure to organic hydroperoxide results in oxidation of the sensing cysteine (Cys16) residue of EstR, leading to a release of the oxidized repressor from the operator sites, thereby allowing transcription and high levels of expression of both genes. The estC is the first organic hydroperoxide-inducible esterase-encoding gene in alphaproteobacteria.
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Affiliation(s)
- Surawach Rittiroongrad
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Department of Biotechnology, and Center of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
| | - Suparat Giengkam
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Department of Biotechnology, and Center of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
- * E-mail:
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76
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OxyR-regulated catalase CatB promotes the virulence in rice via detoxifying hydrogen peroxide in Xanthomonas oryzae pv. oryzae. BMC Microbiol 2016; 16:269. [PMID: 27825304 PMCID: PMC5101826 DOI: 10.1186/s12866-016-0887-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/03/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To facilitate infection, Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, needs to degrade hydrogen peroxide (H2O2) generated by the host defense response via a mechanism that is mediated by the transcriptional regulator OxyR. The catalase (CAT) gene catB has previously been shown to belong to the OxyR regulon in Xoo. However, its expression patterns and function in H2O2 detoxification and bacterial pathogenicity on rice remain to be elucidated. RESULTS The catB gene encodes a putative catalase and is highly conserved in the sequenced strains of Xanthomonas spp. β-galactosidase analysis and electrophoretic mobility shift assays (EMSA) showed that OxyR positively regulated the transcription of catB by directly binding to its promoter region. The quantitative real-time PCR (qRT-PCR) assays revealed that the expression levels of catB and oxyR were significantly induced by H2O2. Deletion of catB or oxyR drastically impaired bacterial viability in the presence of extracellular H2O2 and reduced CAT activity, demonstrating that CatB and OxyR contribute to H2O2 detoxification in Xoo. In addition, ΔcatB and ΔoxyR displayed shorter bacterial blight lesions and reduced bacterial growth in rice compared to the wild-type stain, indicating that CatB and OxyR play essential roles in the virulence of Xoo. CONCLUSIONS Transcription of catB is enhanced by OxyR in response to exogenous H2O2. CatB functions as an active catalase that is required for the full virulence of Xoo in rice.
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77
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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: 32] [Impact Index Per Article: 4.0] [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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78
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Liu Z, Wang H, Zhou Z, Sheng Y, Naseer N, Kan B, Zhu J. Thiol-based switch mechanism of virulence regulator AphB modulates oxidative stress response in Vibrio cholerae. Mol Microbiol 2016; 102:939-949. [PMID: 27625149 DOI: 10.1111/mmi.13524] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2016] [Indexed: 11/30/2022]
Abstract
Bacterial pathogens display versatile gene expression to adapt to changing surroundings. For example, Vibrio cholerae, the causative agent of cholera, utilizes distinct genetic programs to combat reactive oxygen species (ROS) in aquatic environments or during host infection. We previously reported that the virulence activator AphB in V. cholerae is involved in ROS resistance. Here by performing a genetic screen, we show that AphB represses ROS resistance gene ohrA, which is also repressed by another regulator, OhrR. Reduced forms of both AphB and OhrR directly bind to the ohrA promoter and repress its expression, whereas organic hydroperoxides such as cumene hydroperoxide (CHP) deactivate AphB and OhrR. OhrA is critical for V. cholerae adult mouse colonization but is dispensable when the mice are treated with antioxidants. Furthermore, similar to our previous finding that AphB and OhrR exhibit different reduction rates during the shift from oxic to anoxic environments, we found that AphB is also oxidized more slowly than OhrR under peroxide stress or exposure to oxygen. This differential regulation optimizes the expression of ohrA and contributes to V. cholerae's ability to survive in a variety of environmental niches that contain different levels of ROS.
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Affiliation(s)
- Zhi Liu
- Department of Biotechnology, Huazhong University of Science and Technology, Wuhan, China.,Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hui Wang
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Microbiology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhigang Zhou
- Division of Microbiology, Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Ying Sheng
- Department of Microbiology, Nanjing Agricultural University, Nanjing, 210095, China.,Division of Bacterial Infectious Diseases, State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China
| | - Nawar Naseer
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Biao Kan
- Division of Bacterial Infectious Diseases, State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China
| | - Jun Zhu
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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79
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Goulart CL, Barbosa LC, Bisch PM, von Krüger WMA. Catalases and PhoB/PhoR system independently contribute to oxidative stress resistance in Vibrio cholerae O1. MICROBIOLOGY-SGM 2016; 162:1955-1962. [PMID: 27665757 DOI: 10.1099/mic.0.000364] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
All cells are subjected to oxidative stress, a condition under which reactive oxygen species (ROS) production exceeds elimination. Bacterial defences against ROS include synthesis of antioxidant enzymes like peroxidases and catalases. Vibrio cholerae can produce two distinct catalases, KatB and KatG, which contribute to ROS homeostasis. In this study, we analysed the mechanism behind katG and katB expression in two V. cholerae O1 pandemic strains, O395 and N16961, of classical and El Tor biotypes, respectively. Both strains express these genes, especially at stationary phase. However, El Tor N16961 produces higher KatB and KatG levels and is much more resistant to peroxide challenge than the classical strain, confirming a direct relationship between catalase activity and oxidative stress resistance. Moreover, we showed that katG and katB expression levels depend on inorganic phosphate (Pi) availability, in contrast to other bacterial species. In N16961, katB and katG expression is reduced under Pi limitation relative to Pi abundance. Total catalase activity in N16961 and its phoB mutant cells was similar, independently of growth conditions, indicating that the PhoB/PhoR system is not required for katB and katG expression. However, N16961 cells from Pi-limited cultures were 50-100-fold more resistant to H2O2 challenge and accumulated less ROS than phoB mutant cells. Together, these findings suggest that, besides KatB and KatG, the PhoB/PhoR system is an important protective factor against ROS in V. cholerae N16961. They also corroborate previous results from our and other groups, suggesting that the PhoB/PhoR system is fundamental for V. cholerae biology.
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Affiliation(s)
- Carolina L Goulart
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Livia C Barbosa
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paulo M Bisch
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Wanda M A von Krüger
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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80
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Regulation of Organic Hydroperoxide Stress Response by Two OhrR Homologs in Pseudomonas aeruginosa. PLoS One 2016; 11:e0161982. [PMID: 27560944 PMCID: PMC4999210 DOI: 10.1371/journal.pone.0161982] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/15/2016] [Indexed: 11/19/2022] Open
Abstract
Pseudomonas aeruginosa ohrR and ospR are gene homologs encoding oxidant sensing transcription regulators. OspR is known to regulate gpx, encoding a glutathione peroxidase, while OhrR regulates the expression of ohr that encodes an organic peroxide specific peroxiredoxin. Here, we show that ospR mediated gpx expression, like ohrR and ohr, specifically responds to organic hydroperoxides as compared to hydrogen peroxide and superoxide anion. Furthermore, the regulation of these two systems is interconnected. OspR is able to functionally complement an ohrR mutant, i.e. it regulates ohr in an oxidant dependent manner. In an ohrR mutant, in which ohr is derepressed, the induction of gpx expression by organic hydroperoxide is reduced. Likewise, in an ospR mutant, where gpx expression is constitutively high, oxidant dependent induction of ohr expression is reduced. Moreover, in vitro binding assays show that OspR binds the ohr promoter, while OhrR binds the gpx promoter, albeit with lower affinity. The binding of OhrR to the gpx promoter may not be physiologically relevant; however, OspR is shown to mediate oxidant-inducible expression at both promoters. Interestingly, the mechanism of OspR-mediated, oxidant-dependent induction at the two promoters appears to be distinct. OspR required two conserved cysteines (C24 and C134) for oxidant-dependent induction of the gpx promoter, while only C24 is essential at the ohr promoter. Overall, this study illustrates possible connection between two regulatory switches in response to oxidative stress.
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81
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Singh S, Dwivedi SK, Singh VS, Tripathi AK. Expression of alkyl hydroperoxide reductase is regulated negatively by OxyR1 and positively by RpoE2 sigma factor in Azospirillum brasilense Sp7. MICROBIOLOGY-SGM 2016; 162:1870-1883. [PMID: 27557935 DOI: 10.1099/mic.0.000363] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
OxyR proteins are LysR-type transcriptional regulators, which play an important role in responding to oxidative stress in bacteria. Azospirillum brasilense Sp7 harbours two copies of OxyR. The inactivation of the oxyR1, the gene organized divergently to ahpC in A. brasilense Sp7, led to an increased tolerance to alkyl hydroperoxides, which was corroborated by an increase in alkyl hydroperoxide reductase (AhpC) activity, enhanced expression of ahpC :lacZ fusion and increased synthesis of AhpC protein in the oxyR1::km mutant. The upstream region of ahpC promoter harboured a putative OxyR binding site, T-N11-A. Mutation of T, A or both in the T-N11-Amotif caused derepression of ahpC in A. brasilense suggesting that T-N11-A might be the binding site for a negative regulator. Retardation of the electrophoretic mobility of the T-N11-A motif harbouring oxyR1-ahpC intergenic DNA by recombinant OxyR1, under reducing as well as oxidizing conditions, indicated that OxyR1 acts as a negative regulator of ahpC in A. brasilense. Sequence of the promoter of ahpC, predicted on the basis of transcriptional start site, and an enhanced expression of ahpC:lacZ fusion in chrR2::km mutant background suggested that ahpC promoter was RpoE2 dependent. Thus, this study shows that in A. brasilense Sp7, ahpC expression is regulated negatively by OxyR1 but is regulated positively by RpoE2, an oxidative-stress-responsive sigma factor. It also shows that OxyR1 regulates the expression RpoE1, which is known to play an important role during photooxidative stress in A. brasilense.
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Affiliation(s)
- Sudhir Singh
- Laboratory of Bacterial Genetics, Faculty of Science, School of Biotechnology, Banaras Hindu University, Varanasi 221005, India
| | - Susheel Kumar Dwivedi
- Laboratory of Bacterial Genetics, Faculty of Science, School of Biotechnology, Banaras Hindu University, Varanasi 221005, India
| | - Vijay Shankar Singh
- Laboratory of Bacterial Genetics, Faculty of Science, School of Biotechnology, Banaras Hindu University, Varanasi 221005, India
| | - Anil Kumar Tripathi
- Laboratory of Bacterial Genetics, Faculty of Science, School of Biotechnology, Banaras Hindu University, Varanasi 221005, India
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82
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Fang FC, Frawley ER, Tapscott T, Vázquez-Torres A. Discrimination and Integration of Stress Signals by Pathogenic Bacteria. Cell Host Microbe 2016; 20:144-153. [PMID: 27512902 PMCID: PMC5111874 DOI: 10.1016/j.chom.2016.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/23/2016] [Accepted: 07/26/2016] [Indexed: 02/08/2023]
Abstract
For pathogenic bacteria, the ability to sense and respond to environmental stresses encountered within the host is critically important, allowing them to adapt to changing conditions and express virulence genes appropriately. This review considers the diverse molecular mechanisms by which stress conditions are sensed by bacteria, how related signals are discriminated, and how stress responses are integrated, highlighting recent studies in selected bacterial pathogens of clinical relevance.
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Affiliation(s)
- Ferric C Fang
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA, 98195, USA
- Department Laboratory Medicine, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Elaine R Frawley
- Department Laboratory Medicine, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Timothy Tapscott
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Andrés Vázquez-Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
- Veterans Affairs Eastern Colorado Health Care System, 1055 Clermont Street, Denver, CO 80220, USA
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83
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Gao D, Li Y, Zheng E, Liu N, Shao Z, Lu C. Eha, a regulator of Edwardsiella tarda, required for resistance to oxidative stress in macrophages. FEMS Microbiol Lett 2016; 363:fnw192. [PMID: 27511959 DOI: 10.1093/femsle/fnw192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2016] [Indexed: 01/29/2023] Open
Abstract
Edwardsiella tarda is distributed widely in a variety of hosts. Eha has recently been found to be its virulence regulator. In order to explore the mechanism of its regulation, we investigated the survival rates of wild type strain ET13, and its eha mutant and complemented strains in RAW264.7 macrophages under light microscopic observation as well as by counting bacterial CFUs on the plates. All of the different strains could live within the macrophages; however, the intracellular numbers of the wild type were significantly higher than the mutant when the incubation time extended 4 h or 6 h (P < 0.05). Furthermore, more ROS were produced by the mutant-infected cells, indicating that Eha may enhance ET13's capacity to detoxify ROS. In agreement with this, we found that the mutant exhibited more sensitivity by H2O2 disk inhibitory assay and less survival ability with H2O2 treatment. We further demonstrated that the bacterial antioxidant enzymes SodC and KatG were regulated by Eha with qRT-PCR and β-galactosidase assay. Collectively, our data show Eha is required for E. tarda to resist the oxidative stress from the macrophages.
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Affiliation(s)
- Daqing Gao
- Department of Pathogenic Microbiology and Immunology, Southeast University School of Medicine, Nanjing, China
| | - Yuhong Li
- Department of Pathogenic Microbiology and Immunology, Southeast University School of Medicine, Nanjing, China
| | - Enjin Zheng
- Department of Pathogenic Microbiology and Immunology, Southeast University School of Medicine, Nanjing, China
| | - Nian Liu
- Department of Pathogenic Microbiology and Immunology, Southeast University School of Medicine, Nanjing, China
| | - Zeye Shao
- Department of Clinical Lab, Southeast University School of Medicine, Nanjing, China
| | - Chengping Lu
- NanJing Agricultural University, College of Veterinary Medicine, Nanjing, China
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84
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Grinnage-Pulley T, Mu Y, Dai L, Zhang Q. Dual Repression of the Multidrug Efflux Pump CmeABC by CosR and CmeR in Campylobacter jejuni. Front Microbiol 2016; 7:1097. [PMID: 27468281 PMCID: PMC4943160 DOI: 10.3389/fmicb.2016.01097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 06/30/2016] [Indexed: 12/15/2022] Open
Abstract
During transmission and intestinal colonization, Campylobacter jejuni, a major foodborne human pathogen, experiences oxidative stress. CosR, a response regulator in C. jejuni, modulates the oxidative stress response and represses expression of the CmeABC multidrug efflux pump. CmeABC, a key component in resistance to toxic compounds including antimicrobials and bile salts, is also under negative regulation by CmeR, a TetR family transcriptional regulator. How CosR and CmeR interact in binding to the cmeABC promoter and how CosR senses oxidative stress are still unknown. To answer these questions, we conducted various experiments utilizing electrophoretic mobility shift assays and transcriptional fusion assays. CosR and CmeR bound independently to two separate sites of the cmeABC promoter, simultaneously repressing cmeABC expression. This dual binding of CosR and CmeR is optimal with a 17 base pair space between the two binding sites as mutations that shortened the distance between the binding sites decreased binding by CmeR and enhanced cmeABC expression. Additionally, the single cysteine residue (C218) of CosR was sensitive to oxidation, which altered the DNA-binding activity of CosR and dissociated CosR from the cmeABC promoter as determined by electrophoretic mobility shift assay. Replacement of C218 with serine rendered CosR insensitive to oxidation, suggesting a potential role of C218 in sensing oxidative stress and providing a possible mechanism for CosR-mediated response to oxidative stress. These findings reveal a dual regulatory role of CosR and CmeR in modulating cmeABC expression and suggest a potential mechanism that may explain overexpression of cmeABC in response to oxidative stress. Differential expression of cmeABC mediated by CmeR and CosR in response to different signals may facilitate adaptation of Campylobacter to various environmental conditions.
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Affiliation(s)
- Tara Grinnage-Pulley
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
| | - Yang Mu
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
| | - Lei Dai
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
| | - Qijing Zhang
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
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85
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Pillay CS, Eagling BD, Driscoll SRE, Rohwer JM. Quantitative measures for redox signaling. Free Radic Biol Med 2016; 96:290-303. [PMID: 27151506 DOI: 10.1016/j.freeradbiomed.2016.04.199] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/25/2016] [Accepted: 04/29/2016] [Indexed: 12/17/2022]
Abstract
Redox signaling is now recognized as an important regulatory mechanism for a number of cellular processes including the antioxidant response, phosphokinase signal transduction and redox metabolism. While there has been considerable progress in identifying the cellular machinery involved in redox signaling, quantitative measures of redox signals have been lacking, limiting efforts aimed at understanding and comparing redox signaling under normoxic and pathogenic conditions. Here we have outlined some of the accepted principles for redox signaling, including the description of hydrogen peroxide as a signaling molecule and the role of kinetics in conferring specificity to these signaling events. Based on these principles, we then develop a working definition for redox signaling and review a number of quantitative methods that have been employed to describe signaling in other systems. Using computational modeling and published data, we show how time- and concentration- dependent analyses, in particular, could be used to quantitatively describe redox signaling and therefore provide important insights into the functional organization of redox networks. Finally, we consider some of the key challenges with implementing these methods.
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Affiliation(s)
- Ché S Pillay
- School of Life Sciences, University of KwaZulu-Natal, Carbis Road, Pietermaritzburg 3201, South Africa.
| | - Beatrice D Eagling
- School of Life Sciences, University of KwaZulu-Natal, Carbis Road, Pietermaritzburg 3201, South Africa
| | - Scott R E Driscoll
- School of Life Sciences, University of KwaZulu-Natal, Carbis Road, Pietermaritzburg 3201, South Africa
| | - Johann M Rohwer
- Department of Biochemistry, Stellenbosch University, Private Bag X1, Matieland, 7602 Stellenbosch, South Africa
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86
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Bang YJ, Lee ZW, Kim D, Jo I, Ha NC, Choi SH. OxyR2 Functions as a Three-state Redox Switch to Tightly Regulate Production of Prx2, a Peroxiredoxin of Vibrio vulnificus. J Biol Chem 2016; 291:16038-47. [PMID: 27268058 DOI: 10.1074/jbc.m115.710343] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Indexed: 11/06/2022] Open
Abstract
The bacterial transcriptional regulator OxyR is known to function as a two-state redox switch. OxyR senses cellular levels of H2O2 via a "sensing cysteine" that switches from the reduced to a disulfide state upon H2O2 exposure, inducing the expression of antioxidant genes. The reduced and disulfide states of OxyR, respectively, bind to extended and compact regions of DNA, where the reduced state blocks and the oxidized state allows transcription and further induces target gene expression by interacting with RNA polymerase. Vibrio vulnificus OxyR2 senses H2O2 with high sensitivity and induces the gene encoding the antioxidant Prx2. In this study, we used mass spectrometry to identify a third redox state of OxyR2, in which the sensing cysteine was overoxidized to S-sulfonated cysteine (Cys-SO3H) by high H2O2 in vitro and in vivo, where the modification deterred the transcription of prx2 The DNA binding preferences of OxyR25CA-C206D, which mimics overoxidized OxyR2, suggested that overoxidized OxyR2 binds to the extended DNA site, masking the -35 region of the prx2 promoter. These combined results demonstrate that OxyR2 functions as a three-state redox switch to tightly regulate the expression of prx2, preventing futile production of Prx2 in cells exposed to high levels of H2O2 sufficient to inactivate Prx2. We further provide evidence that another OxyR homolog, OxyR1, displays similar three-state behavior, inviting further exploration of this phenomenon as a potentially general regulatory mechanism.
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Affiliation(s)
- Ye-Ji Bang
- From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea
| | - Zee-Won Lee
- From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea
| | - Dukyun Kim
- From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea
| | - Inseong Jo
- the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea
| | - Nam-Chul Ha
- the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea
| | - Sang Ho Choi
- From the National Research Laboratory of Molecular Microbiology and Toxicology and the Department of Agricultural Biotechnology, and Center for Food Safety and Toxicology, Seoul National University, Seoul 08826, Korea
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Kim JH, Ji CJ, Ju SY, Yang YM, Ryu SH, Kwon Y, Won YB, Lee YE, Youn H, Lee JW. Bacillus licheniformis Contains Two More PerR-Like Proteins in Addition to PerR, Fur, and Zur Orthologues. PLoS One 2016; 11:e0155539. [PMID: 27176811 PMCID: PMC4866751 DOI: 10.1371/journal.pone.0155539] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/29/2016] [Indexed: 11/18/2022] Open
Abstract
The ferric uptake regulator (Fur) family proteins include sensors of Fe (Fur), Zn (Zur), and peroxide (PerR). Among Fur family proteins, Fur and Zur are ubiquitous in most prokaryotic organisms, whereas PerR exists mainly in Gram positive bacteria as a functional homologue of OxyR. Gram positive bacteria such as Bacillus subtilis, Listeria monocytogenes and Staphylococcus aureus encode three Fur family proteins: Fur, Zur, and PerR. In this study, we identified five Fur family proteins from B. licheniformis: two novel PerR-like proteins (BL00690 and BL00950) in addition to Fur (BL05249), Zur (BL03703), and PerR (BL00075) homologues. Our data indicate that all of the five B. licheniformis Fur homologues contain a structural Zn2+ site composed of four cysteine residues like many other Fur family proteins. Furthermore, we provide evidence that the PerR-like proteins (BL00690 and BL00950) as well as PerRBL (BL00075), but not FurBL (BL05249) and ZurBL (BL03703), can sense H2O2 by histidine oxidation with different sensitivity. We also show that PerR2 (BL00690) has a PerR-like repressor activity for PerR-regulated genes in vivo. Taken together, our results suggest that B. licheniformis contains three PerR subfamily proteins which can sense H2O2 by histidine oxidation not by cysteine oxidation, in addition to Fur and Zur.
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Affiliation(s)
- Jung-Hoon Kim
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Chang-Jun Ji
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Shin-Yeong Ju
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Yoon-Mo Yang
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Su-Hyun Ryu
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Yumi Kwon
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Young-Bin Won
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Yeh-Eun Lee
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | - Hwan Youn
- Department of Biology, California State University Fresno, Fresno, California, 93740–8034, United States of America
| | - Jin-Won Lee
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
- * E-mail:
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88
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Li S, Li Y, Chen G, Zhang J, Xu F, Wu M. Restraining reactive oxygen species in Listeria monocytogenes promotes the apoptosis of glial cells. Redox Rep 2016; 22:190-196. [PMID: 27120397 DOI: 10.1080/13510002.2016.1173327] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVES Listeria monocytogenes is a facultative anaerobic foodborne pathogen that can traverse the blood-brain barrier and cause brain infection. L. monocytogenes infection induces host cell apoptosis in several cell types. In this study, we investigated the apoptosis of human glioma cell line U251 invaded by L. monocytogenes and evaluated the function of bacterial reactive oxygen species (ROS) during infection. METHODS Bacterial ROS level was reduced by carrying out treatment with N-acetyl cysteine (NAC) and diphenyleneiodonium chloride (DPI). After infection, the apoptosis of U251 cells was examined by flow cytometry assay and propidium iodide staining. RESULTS DPI and NAC efficiently decreased ROS level in L. monocytogenes without affecting bacterial growth. Moreover, the apoptosis of glial cells was enhanced upon invasion of DPI- and NAC-pretreated L. monocytogenes. DISCUSSION Results indicate that the apoptosis of glial cells can be induced by L. monocytogenes, and that the inhibition of bacterial ROS increases the apoptosis of host cells.
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Affiliation(s)
- Sen Li
- a School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093 , China
| | - Yixuan Li
- a School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093 , China
| | - Guowei Chen
- a School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093 , China
| | - Jingchen Zhang
- b Certification and Review Center, Shanghai Municipal Food and Drug, Administration , Shanghai 200020 , China
| | - Fei Xu
- a School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093 , China
| | - Man Wu
- a School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093 , China
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89
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Vicente CSL, Nascimento FX, Ikuyo Y, Cock PJA, Mota M, Hasegawa K. The genome and genetics of a high oxidative stress tolerant Serratia sp. LCN16 isolated from the plant parasitic nematode Bursaphelenchus xylophilus. BMC Genomics 2016; 17:301. [PMID: 27108223 PMCID: PMC4841953 DOI: 10.1186/s12864-016-2626-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/16/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Pine wilt disease (PWD) is a worldwide threat to pine forests, and is caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus. Bacteria are known to be associated with PWN and may have an important role in PWD. Serratia sp. LCN16 is a PWN-associated bacterium, highly resistant to oxidative stress in vitro, and which beneficially contributes to the PWN survival under these conditions. Oxidative stress is generated as a part of the basal defense mechanism used by plants to combat pathogenic invasion. Here, we studied the biology of Serratia sp. LCN16 through genome analyses, and further investigated, using reverse genetics, the role of two genes directly involved in the neutralization of H2O2, namely the H2O2 transcriptional factor oxyR; and the H2O2-targeting enzyme, catalase katA. RESULTS Serratia sp. LCN16 is phylogenetically most closely related to the phytosphere group of Serratia, which includes S. proteamaculans, S. grimessi and S. liquefaciens. Likewise, Serratia sp. LCN16 shares many features with endophytes (plant-associated bacteria), such as genes coding for plant polymer degrading enzymes, iron uptake/transport, siderophore and phytohormone synthesis, aromatic compound degradation and detoxification enzymes. OxyR and KatA are directly involved in the high tolerance to H2O2 of Serratia sp. LCN16. Under oxidative stress, Serratia sp. LCN16 expresses katA independently of OxyR in contrast with katG which is under positive regulation of OxyR. Serratia sp. LCN16 mutants for oxyR (oxyR::int(614)) and katA (katA::int(808)) were sensitive to H2O2 in relation with wild-type, and both failed to protect the PWN from H2O2-stress exposure. Moreover, both mutants showed different phenotypes in terms of biofilm production and swimming/swarming behaviors. CONCLUSIONS This study provides new insights into the biology of PWN-associated bacteria Serratia sp. LCN16 and its extreme resistance to oxidative stress conditions, encouraging further research on the potential role of this bacterium in interaction with PWN in planta environment.
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Affiliation(s)
- Claudia S L Vicente
- NemaLab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia, Universidade de Évora, Núcleo da Mitra, Ap. 94, 7002-554, Évora, Portugal.,Department of Environmental Biology, College of Bioscience & Biotechnology, Chubu University, 1200 Matsumoto, Kasugai, Aichi, 487-8501, Japan
| | - Francisco X Nascimento
- NemaLab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia, Universidade de Évora, Núcleo da Mitra, Ap. 94, 7002-554, Évora, Portugal
| | - Yoriko Ikuyo
- Department of Environmental Biology, College of Bioscience & Biotechnology, Chubu University, 1200 Matsumoto, Kasugai, Aichi, 487-8501, Japan
| | - Peter J A Cock
- Information and Computational Sciences group (PJAC), The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Manuel Mota
- NemaLab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia, Universidade de Évora, Núcleo da Mitra, Ap. 94, 7002-554, Évora, Portugal.,Departamento de Ciências da Vida, Universidade Lusófona de Humanidades e Tecnologias, Lisboa, Portugal
| | - Koichi Hasegawa
- Department of Environmental Biology, College of Bioscience & Biotechnology, Chubu University, 1200 Matsumoto, Kasugai, Aichi, 487-8501, Japan.
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90
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Liu X, Sun M, Cheng Y, Yang R, Wen Y, Chen Z, Li J. OxyR is a key regulator in response to oxidative stress in Streptomyces avermitilis. MICROBIOLOGY-SGM 2016; 162:707-716. [PMID: 26839064 DOI: 10.1099/mic.0.000251] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The role of the H2O2-sensing transcriptional regulator OxyR in oxidative stress responses in Streptomyces avermitilis was investigated. An oxyR deletion mutant was more sensitive to H2O2 and tert-butyl hydroperoxide than was the WT strain, indicating that OxyR mediates the defensive system against H2O2 and organic peroxide. Evidence presented herein suggests that in cells treated with exogenous H2O2, the oxidized form of OxyR activated expression of ahpCD by binding to a palindromic sequence of the promoter region. Oxidized OxyR also induced expression of other antioxidant enzymes (KatA1, KatA2, KatA3 and OhrB1) and oxidative stress regulators (CatR, OhrR and σR). The thiol-oxidative stress regulator gene sigR was regulated at the transcription level by OxyR. We conclude that OxyR is necessary to activate transcription of sigR from the σR-dependent promoter to express an unstable larger isoform of σR during oxidative stress. In response to oxidative stress, OxyR facilitates rapid production of H2O2-scavenging enzymes to repair oxidative damage through direct regulation and cascaded regulation of CatR, OhrR and σR.
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Affiliation(s)
- Xingchao Liu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | - Meng Sun
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | - Yaqing Cheng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | - Renjun Yang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | - Ying Wen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | - Zhi Chen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | - Jilun Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
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91
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Netto LES, de Oliveira MA, Tairum CA, da Silva Neto JF. Conferring specificity in redox pathways by enzymatic thiol/disulfide exchange reactions. Free Radic Res 2016; 50:206-45. [DOI: 10.3109/10715762.2015.1120864] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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92
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Functions of VPA1418 and VPA0305 Catalase Genes in Growth of Vibrio parahaemolyticus under Oxidative Stress. Appl Environ Microbiol 2016; 82:1859-1867. [PMID: 26746716 DOI: 10.1128/aem.02547-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/04/2016] [Indexed: 12/19/2022] Open
Abstract
The marine foodborne enteropathogen Vibrio parahaemolyticus has four putative catalase genes. The functions of two katE-homologous genes, katE1 (VPA1418) and katE2 (VPA0305), in the growth of this bacterium were examined using gene deletion mutants with or without complementary genes. The growth of the mutant strains in static or shaken cultures in a rich medium at 37°C or at low temperatures (12 and 4°C), with or without competition from Escherichia coli, did not differ from that of the parent strain. When 175 μM extrinsic H2O2 was added to the culture medium, bacterial growth of the ΔkatE1 strain was delayed and growth of the ΔkatE1 ΔkatE2 and ΔkatE1 ΔahpC1 double mutant strains was completely inhibited at 37°C for 8 h. The sensitivity of the ΔkatE1 strain to the inhibition of growth by H2O2 was higher at low incubation temperatures (12 and 22°C) than at 37°C. The determined gene expression of these catalase and ahpC genes revealed that katE1 was highly expressed in the wild-type strain at 22°C under H2O2 stress, while the katE2 and ahpC genes may play an alternate or compensatory role in the ΔkatE1 strain. This study demonstrated that katE1 encodes the chief functional catalase for detoxifying extrinsic H2O2 during logarithmic growth and that the function of these genes was influenced by incubation temperature.
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93
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Liu Z, Wang H, Zhou Z, Naseer N, Xiang F, Kan B, Goulian M, Zhu J. Differential Thiol-Based Switches Jump-Start Vibrio cholerae Pathogenesis. Cell Rep 2015; 14:347-54. [PMID: 26748713 DOI: 10.1016/j.celrep.2015.12.038] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/10/2015] [Accepted: 12/06/2015] [Indexed: 12/01/2022] Open
Abstract
Bacterial pathogens utilize gene expression versatility to adapt to environmental changes. Vibrio cholerae, the causative agent of cholera, encounters redox-potential changes when it transitions from oxygen-rich aquatic reservoirs to the oxygen-limiting human gastrointestinal tract. We previously showed that the virulence regulator AphB uses thiol-based switches to sense the anoxic host environment and transcriptionally activate the key virulence activator tcpP. Here, by performing a high-throughput transposon sequencing screen in vivo, we identified OhrR as another regulator that enables V. cholerae rapid anoxic adaptation. Like AphB, reduced OhrR binds to and regulates the tcpP promoter. OhrR and AphB displayed differential dynamics in response to redox-potential changes: OhrR is reduced more rapidly than AphB. Furthermore, OhrR thiol modification is required for rapid activation of virulence and successful colonization. This reveals a mechanism whereby bacterial pathogens employ posttranslational modifications of multiple transcription factors to sense and adapt to dynamic environmental changes.
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Affiliation(s)
- Zhi Liu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hui Wang
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Microbiology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhigang Zhou
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Nawar Naseer
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Fu Xiang
- College of Life Sciences, Huanggang Normal University, Huanggang 438000, China
| | - Biao Kan
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Mark Goulian
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jun Zhu
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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94
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Fu H, Yuan J, Gao H. Microbial oxidative stress response: Novel insights from environmental facultative anaerobic bacteria. Arch Biochem Biophys 2015; 584:28-35. [DOI: 10.1016/j.abb.2015.08.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/19/2015] [Accepted: 08/20/2015] [Indexed: 02/03/2023]
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95
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Molecular mechanism involved in the response to hydrogen peroxide stress in Acinetobacter oleivorans DR1. Appl Microbiol Biotechnol 2015; 99:10611-26. [PMID: 26298700 DOI: 10.1007/s00253-015-6914-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/26/2015] [Accepted: 08/03/2015] [Indexed: 10/23/2022]
Abstract
Two-dimensional gel electrophoresis was conducted to investigate the effect of H2O2 on whole protein expression in Acinetobacter oleivorans DR1. Functional classification of 13 upregulated proteins using MALDI-TOF mass spectrometry showed relationships with oxidative stress, energy production and conversion, nucleotide and amino acid metabolism, membrane-related, ion transport, and chaperone-related functions. Alignment of OxyR-binding regions from Pseudomonas aeruginosa and Escherichia coli with promoters of identified proteins revealed that only ahpC, ahpF, and trxB (thioredoxin-disulfide reductase) genes, along with a newly found oprC (putative outer membrane receptor protein) gene, have OxyR-binding sites. The oxyR and ahpC mutants were more sensitive to H2O2 and showed growth defects in both nutritional and n-hexadecane-amended media. Four catalases present in the genome of A. oleivorans DR1 were not detected, which led us to confirm the expression and activity of those catalases in the presence of H2O2. The expression patterns of the four catalase genes differed at different concentrations of H2O2. Interestingly, the promoters of both known OxyR-controlled katG gene (AOLE_17390) and putative small catalase gene (AOLE_09800) have OxyR-binding sites. Gel-shift assay confirmed OxyR binding to the promoter regions of newly identified OxyR-controlled genes encoding OprC and a putative catalase. Hierarchical expression and OxyR-binding of several OxyR-controlled genes suggested that concentration is an important factor in inducing the set of genes under H2O2 stress.
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96
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Pelliciari S, Vannini A, Roncarati D, Danielli A. The allosteric behavior of Fur mediates oxidative stress signal transduction in Helicobacter pylori. Front Microbiol 2015; 6:840. [PMID: 26347726 PMCID: PMC4541418 DOI: 10.3389/fmicb.2015.00840] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/31/2015] [Indexed: 12/19/2022] Open
Abstract
The microaerophilic gastric pathogen Helicobacter pylori is exposed to oxidative stress originating from the aerobic environment, the oxidative burst of phagocytes and the formation of reactive oxygen species, catalyzed by iron excess. Accordingly, the expression of genes involved in oxidative stress defense have been repeatedly linked to the ferric uptake regulator Fur. Moreover, mutations in the Fur protein affect the resistance to metronidazole, likely due to loss-of-function in the regulation of genes involved in redox control. Although many advances in the molecular understanding of HpFur function were made, little is known about the mechanisms that enable Fur to mediate the responses to oxidative stress. Here we show that iron-inducible, apo-Fur repressed genes, such as pfr and hydA, are induced shortly after oxidative stress, while their oxidative induction is lost in a fur knockout strain. On the contrary, holo-Fur repressed genes, such as frpB1 and fecA1, vary modestly in response to oxidative stress. This indicates that the oxidative stress signal specifically targets apo-Fur repressed genes, rather than impairing indiscriminately the regulatory function of Fur. Footprinting analyses showed that the oxidative signal strongly impairs the binding affinity of Fur toward apo-operators, while the binding toward holo-operators is less affected. Further evidence is presented that a reduced state of Fur is needed to maintain apo-repression, while oxidative conditions shift the preferred binding architecture of Fur toward the holo-operator binding conformation, even in the absence of iron. Together the results demonstrate that the allosteric regulation of Fur enables transduction of oxidative stress signals in H. pylori, supporting the concept that apo-Fur repressed genes can be considered oxidation inducible Fur regulatory targets. These findings may have important implications in the study of H. pylori treatment and resistance to antibiotics.
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Affiliation(s)
- Simone Pelliciari
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna , Bologna, Italy
| | - Andrea Vannini
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna , Bologna, Italy
| | - Davide Roncarati
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna , Bologna, Italy
| | - Alberto Danielli
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna , Bologna, Italy
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97
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Butcher J, Handley RA, van Vliet AHM, Stintzi A. Refined analysis of the Campylobacter jejuni iron-dependent/independent Fur- and PerR-transcriptomes. BMC Genomics 2015; 16:498. [PMID: 26141822 PMCID: PMC4491227 DOI: 10.1186/s12864-015-1661-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 05/29/2015] [Indexed: 12/30/2022] Open
Abstract
Background The genome of Campylobacter jejuni contains two iron activated Fur-family transcriptional regulators, CjFur and CjPerR, which are primarily responsible for regulating iron homeostasis and oxidative stress respectively. Both transcriptional regulators have been previously implicated in regulating diverse functions beyond their primary roles in C. jejuni. To further characterize their regulatory networks, RNA-seq was used to define the transcriptional profiles of C. jejuni NCTC11168 wild type, Δfur, ΔperR and ΔfurΔperR isogenic deletion mutants under both iron-replete and iron-limited conditions. Results It was found that 202 genes were differentially expressed in at least one mutant under iron-replete conditions and 331 genes were differentially expressed in at least one mutant under iron-limited conditions. The CjFur and CjPerR transcriptomes characterized in this study were compared to those previously identified using microarray profiling and found to be more extensive than previously understood. Interestingly, our results indicate that CjFur/CjPerR appear to co-regulate the expression of flagellar biogenesis genes in an opposing and iron-independent fashion. Moreover the ΔfurΔperR isogenic deletion mutant revealed that CjFur and CjPerR can compensate for each other in certain cases, suggesting that both regulators may compete for binding to specific promoters. Conclusions The CjFur and CjPerR transcriptomes are larger than previously reported. In particular, deletion of perR results in the differential expression of a large group of genes in the absence of iron, suggesting that CjPerR may also regulate genes in an iron-independent manner, similar to what has already been demonstrated with CjFur. Moreover, subsets of genes were found which are only differentially expressed when both CjFur and CjPerR are deleted and includes genes that appear to be simultaneously activated by CjFur and repressed by CjPerR. In particular the iron-independent co-regulation of flagellar biogenesis by CjFur/CjPerR represents a potentially novel regulatory function for these proteins. These findings represent additional modes of co-regulation by these two transcriptional regulators in C. jejuni. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1661-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James Butcher
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada.
| | - Rebecca A Handley
- Institute of Food Research, Gut Health and Food Safety Programme, Norwich Research Park, Norwich, UK.
| | - Arnoud H M van Vliet
- Institute of Food Research, Gut Health and Food Safety Programme, Norwich Research Park, Norwich, UK.
| | - Alain Stintzi
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada.
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98
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Ji CJ, Kim JH, Won YB, Lee YE, Choi TW, Ju SY, Youn H, Helmann JD, Lee JW. Staphylococcus aureus PerR Is a Hypersensitive Hydrogen Peroxide Sensor using Iron-mediated Histidine Oxidation. J Biol Chem 2015; 290:20374-86. [PMID: 26134568 DOI: 10.1074/jbc.m115.664961] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Indexed: 12/23/2022] Open
Abstract
In many Gram-positive bacteria PerR is a major peroxide sensor whose repressor activity is dependent on a bound metal cofactor. The prototype for PerR sensors, the Bacillus subtilis PerRBS protein, represses target genes when bound to either Mn(2+) or Fe(2+) as corepressor, but only the Fe(2+)-bound form responds to H2O2. The orthologous protein in the human pathogen Staphylococcus aureus, PerRSA, plays important roles in H2O2 resistance and virulence. However, PerRSA is reported to only respond to Mn(2+) as corepressor, which suggests that it might rely on a distinct, iron-independent mechanism for H2O2 sensing. Here we demonstrate that PerRSA uses either Fe(2+) or Mn(2+) as corepressor, and that, like PerRBS, the Fe(2+)-bound form of PerRSA senses physiological levels of H2O2 by iron-mediated histidine oxidation. Moreover, we show that PerRSA is poised to sense very low levels of endogenous H2O2, which normally cannot be sensed by B. subtilis PerRBS. This hypersensitivity of PerRSA accounts for the apparent lack of Fe(2+)-dependent repressor activity and consequent Mn(2+)-specific repressor activity under aerobic conditions. We also provide evidence that the activity of PerRSA is directly correlated with virulence, whereas it is inversely correlated with H2O2 resistance, suggesting that PerRSA may be an attractive target for the control of S. aureus pathogenesis.
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Affiliation(s)
- Chang-Jun Ji
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Jung-Hoon Kim
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Young-Bin Won
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Yeh-Eun Lee
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Tae-Woo Choi
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Shin-Yeong Ju
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Hwan Youn
- the Department of Biology, California State University Fresno, Fresno, California 93740-8034, and
| | - John D Helmann
- the Department of Microbiology, Cornell University, Ithaca, New York 14853-8101
| | - Jin-Won Lee
- From the Department of Life Science and Research Center for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea,
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99
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Shi M, Wan F, Mao Y, Gao H. Unraveling the Mechanism for the Viability Deficiency of Shewanella oneidensis oxyR Null Mutant. J Bacteriol 2015; 197:2179-2189. [PMID: 25897035 PMCID: PMC4455265 DOI: 10.1128/jb.00154-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 04/16/2015] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Oxidative stresses triggered by reactive oxygen species (ROS) that damage various cellular components are unavoidable for virtually all living organisms. In defense, microorganisms have evolved sophisticated mechanisms to sense, respond to, and battle against ROS. Shewanella oneidensis, an important research model for applied and environmental microbes, employs OxyR to mediate the response to H2O2 by derepressing the production of the major H2O2 scavenger KatB as a major means toward these goals. Surprisingly, despite enhanced H2O2 degradation, the oxyR mutant carries a viability deficiency phenotype (plating defect), which can be suppressed by the addition of exogenous iron species. Experiments showed that the defect was not due to iron starvation. Rather, multiple lines of evidence suggested that H2O2 generated abiotically in lysogeny broth (LB) is responsible for the defect by quickly killing mutant cells. We then showed that the iron species suppressed the plating defect by two distinct mechanisms, either as an H2O2 scavenger without involving living cells or as an environmental cue to stimulate an OxyR-independent response to help cells cope with oxidative stress. Based on the suppression of the plating defect by overproduction of H2O2 scavengers in vivo, we propose that cellular components that are vulnerable to H2O2 and responsible for the defect may reside outside the cytoplasm. IMPORTANCE In bacteria, OxyR is the major regulator controlling the cellular response to H2O2. The loss of OxyR results in reduced viability in many species, but the underlying mechanism is unknown. We showed in S. oneidensis that this defect was due to H2O2 generated abiotically in LB. We then showed that this defect could be corrected by the addition of Fe(2+) or catalase to the LB or increased intracellular production of catalase. Further analyses revealed that Fe(2+) was able not only to decompose H2O2 directly but also to stimulate the activity of OxyR-independent H2O2-scavenging enzymes. Our data indicate that iron species play a previously underappreciated role in protecting cells from H2O2 in environments.
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Affiliation(s)
- Miaomiao Shi
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
| | - Fen Wan
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
| | - Yinting Mao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province, Hangzhou, Zhejiang, China
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Abstract
Bacteria live in a toxic world in which their competitors excrete hydrogen peroxide or superoxide-generating redox-cycling compounds. They protect themselves by activating regulons controlled by the OxyR, PerR, and SoxR transcription factors. OxyR and PerR sense peroxide when it oxidizes key thiolate or iron moieties, respectively; they then induce overlapping sets of proteins that defend their vulnerable metalloenzymes. An additional role for OxyR in detecting electrophilic compounds is possible. In some nonenteric bacteria, SoxR appears to control the synthesis and export of redox-cycling compounds, whereas in the enteric bacteria it defends the cell against the same agents. When these compounds oxidize its iron-sulfur cluster, SoxR induces proteins that exclude, excrete, or modify them. It also induces enzymes that defend the cell against the superoxide that such compounds make. Recent work has brought new insight into the biochemistry and physiology of these responses, and comparative studies have clarified their evolutionary histories.
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Affiliation(s)
- James A Imlay
- Department of Microbiology, University of Illinois, Urbana, Illinois 61801;
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