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Monothiol Glutaredoxin Is Essential for Oxidative Stress Protection and Virulence in Pseudomonas aeruginosa. Appl Environ Microbiol 2023; 89:e0171422. [PMID: 36533942 PMCID: PMC9888271 DOI: 10.1128/aem.01714-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glutaredoxins (Grxs), ubiquitous redox enzymes belonging to the thioredoxin family, catalyze the reduction of thiol-disulfide exchange reactions in a glutathione-dependent manner. A Pseudomonas aeruginosa ΔgrxD mutant exhibited hypersensitivity to oxidative stress-generating agents, such as paraquat (PQ) and cumene hydroperoxide (CHP). In vitro studies showed that P. aeruginosa GrxD acts as an electron donor for organic hydroperoxide resistance enzyme (Ohr) during CHP degradation. The ectopic expression of iron-sulfur cluster ([Fe-S]) carrier proteins, including ErpA, IscA, and NfuA, complements the function of GrxD in the ΔgrxD mutant under PQ toxicity. Constitutively high expression of iscR, nfuA, tpx, and fprB was observed in the ΔgrxD mutant. These results suggest that GrxD functions as a [Fe-S] cluster carrier protein involved in [Fe-S] cluster maturation. Moreover, the ΔgrxD mutant demonstrates attenuated virulence in a Drosophila melanogaster host model. Altogether, the data shed light on the physiological role of GrxD in oxidative stress protection and virulence of the human pathogen, P. aeruginosa. IMPORTANCE Glutaredoxins (Grxs) are ubiquitous disulfide reductase enzymes. Monothiol Grxs, containing a CXXS motif, play an essential role in iron homeostasis and maturation of [Fe-S] cluster proteins in various organisms. We now establish that the human pathogen Pseudomonas aeruginosa GrxD is crucial for bacterial virulence, maturation of [Fe-S] clusters and facilitation of Ohr enzyme activity. GrxD contains a conserved signature monothiol motif (C29GFS), in which C29 is essential for its function in an oxidative stress protection. Our findings reveal the physiological roles of GrxD in oxidative stress protection and virulence of P. aeruginosa.
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In vitro study on novel bioactive peptides with antioxidant and antihypertensive properties from edible rhizomes. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.110227] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Tondo ML, de Pedro-Jové R, Vandecaveye A, Piskulic L, Orellano EG, Valls M. KatE From the Bacterial Plant Pathogen Ralstonia solanacearum Is a Monofunctional Catalase Controlled by HrpG That Plays a Major Role in Bacterial Survival to Hydrogen Peroxide. FRONTIERS IN PLANT SCIENCE 2020; 11:1156. [PMID: 32849714 PMCID: PMC7412880 DOI: 10.3389/fpls.2020.01156] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/16/2020] [Indexed: 05/31/2023]
Abstract
Ralstonia solanacearum is the causative agent of bacterial wilt disease on a wide range of plant species. Besides the numerous bacterial activities required for host invasion, those involved in the adaptation to the plant environment are key for the success of infection. R. solanacearum ability to cope with the oxidative burst produced by the plant is likely one of the activities required to grow parasitically. Among the multiple reactive oxygen species (ROS)-scavenging enzymes predicted in the R. solanacearum GMI1000 genome, a single monofunctional catalase (KatE) and two KatG bifunctional catalases were identified. In this work, we show that these catalase activities are active in bacterial protein extracts and demonstrate by gene disruption and mutant complementation that the monofunctional catalase activity is encoded by katE. Different strategies were used to evaluate the role of KatE in bacterial physiology and during the infection process that causes bacterial wilt. We show that the activity of the enzyme is maximal during exponential growth in vitro and this growth-phase regulation occurs at the transcriptional level. Our studies also demonstrate that katE expression is transcriptionally activated by HrpG, a central regulator of R. solanacearum induced upon contact with the plant cells. In addition, we reveal that even though both KatE and KatG catalase activities are induced upon hydrogen peroxide treatment, KatE has a major effect on bacterial survival under oxidative stress conditions and especially in the adaptive response of R. solanacearum to this oxidant. The katE mutant strain also exhibited differences in the structural characteristics of the biofilms developed on an abiotic surface in comparison to wild-type cells, but not in the overall amount of biofilm production. The role of catalase KatE during the interaction with its host plant tomato is also studied, revealing that disruption of this gene has no effect on R. solanacearum virulence or bacterial growth in leave tissues, which suggests a minor role for this catalase in bacterial fitness in planta. Our work provides the first characterization of the R. solanacearum catalases and identifies KatE as a bona fide monofunctional catalase with an important role in bacterial protection against oxidative stress.
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Affiliation(s)
- María Laura Tondo
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
- Instituto de Ingeniería Ambiental, Química y Biotecnología Aplicada (INGEBIO), Facultad de Química e Ingeniería del Rosario, Pontificia Universidad Católica Argentina (UCA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario, Argentina
| | - Roger de Pedro-Jové
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Catalonia, Spain
- Department of Genetics, University of Barcelona, Barcelona, Spain
| | - Agustina Vandecaveye
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario, Argentina
| | - Laura Piskulic
- Área Estadística y Procesamiento de Datos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Elena G. Orellano
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario, Argentina
| | - Marc Valls
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Catalonia, Spain
- Department of Genetics, University of Barcelona, Barcelona, Spain
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4
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Meyer T, Thiour-Mauprivez C, Wisniewski-Dyé F, Kerzaon I, Comte G, Vial L, Lavire C. Ecological Conditions and Molecular Determinants Involved in Agrobacterium Lifestyle in Tumors. FRONTIERS IN PLANT SCIENCE 2019; 10:978. [PMID: 31417593 PMCID: PMC6683767 DOI: 10.3389/fpls.2019.00978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/11/2019] [Indexed: 05/07/2023]
Abstract
The study of pathogenic agents in their natural niches allows for a better understanding of disease persistence and dissemination. Bacteria belonging to the Agrobacterium genus are soil-borne and can colonize the rhizosphere. These bacteria are also well known as phytopathogens as they can cause tumors (crown gall disease) by transferring a DNA region (T-DNA) into a wide range of plants. Most reviews on Agrobacterium are focused on virulence determinants, T-DNA integration, bacterial and plant factors influencing the efficiency of genetic transformation. Recent research papers have focused on the plant tumor environment on the one hand, and genetic traits potentially involved in bacterium-plant interactions on the other hand. The present review gathers current knowledge about the special conditions encountered in the tumor environment along with the Agrobacterium genetic determinants putatively involved in bacterial persistence inside a tumor. By integrating recent metabolomic and transcriptomic studies, we describe how tumors develop and how Agrobacterium can maintain itself in this nutrient-rich but stressful and competitive environment.
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Affiliation(s)
- Thibault Meyer
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Clémence Thiour-Mauprivez
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
- Biocapteurs-Analyses-Environment, Universite de Perpignan Via Domitia, Perpignan, France
- Laboratoire de Biodiversite et Biotechnologies Microbiennes, USR 3579 Sorbonne Universites (UPMC) Paris 6 et CNRS Observatoire Oceanologique, Paris, France
| | | | - Isabelle Kerzaon
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Gilles Comte
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Ludovic Vial
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Céline Lavire
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
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5
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Perry EK, Newman DK. The transcription factors ActR and SoxR differentially affect the phenazine tolerance of Agrobacterium tumefaciens. Mol Microbiol 2019; 112:199-218. [PMID: 31001852 PMCID: PMC6615960 DOI: 10.1111/mmi.14263] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2019] [Indexed: 01/01/2023]
Abstract
Bacteria in soils encounter redox-active compounds, such as phenazines, that can generate oxidative stress, but the mechanisms by which different species tolerate these compounds are not fully understood. Here, we identify two transcription factors, ActR and SoxR, that play contrasting yet complementary roles in the tolerance of the soil bacterium Agrobacterium tumefaciens to phenazines. We show that ActR promotes phenazine tolerance by proactively driving expression of a more energy-efficient terminal oxidase at the expense of a less efficient alternative, which may affect the rate at which phenazines abstract electrons from the electron transport chain (ETC) and thereby generate reactive oxygen species. SoxR, on the other hand, responds to phenazines by inducing expression of several efflux pumps and redox-related genes, including one of three copies of superoxide dismutase and five novel members of its regulon that could not be computationally predicted. Notably, loss of ActR is far more detrimental than loss of SoxR at low concentrations of phenazines, and also increases dependence on the otherwise functionally redundant SoxR-regulated superoxide dismutase. Our results thus raise the intriguing possibility that the composition of an organism's ETC may be the driving factor in determining sensitivity or tolerance to redox-active compounds.
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Affiliation(s)
- Elena K Perry
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA
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6
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Gonzalez-Mula A, Lachat J, Mathias L, Naquin D, Lamouche F, Mergaert P, Faure D. The biotroph Agrobacterium tumefaciens thrives in tumors by exploiting a wide spectrum of plant host metabolites. THE NEW PHYTOLOGIST 2019; 222:455-467. [PMID: 30447163 DOI: 10.1111/nph.15598] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 11/03/2018] [Indexed: 05/12/2023]
Abstract
Agrobacterium tumefaciens is a niche-constructing biotroph that exploits host plant metabolites. We combined metabolomics, transposon-sequencing (Tn-seq), transcriptomics, and reverse genetics to characterize A. tumefaciens pathways involved in the exploitation of resources from the Solanum lycopersicum host plant. Metabolomics of healthy stems and plant tumors revealed the common (e.g. sucrose, glutamate) and enriched (e.g. opines, γ-aminobutyric acid (GABA), γ-hydroxybutyric acid (GHB), pyruvate) metabolites that A. tumefaciens could use as nutrients. Tn-seq and transcriptomics pinpointed the genes that are crucial and/or upregulated when the pathogen grew on either sucrose (pgi, kdgA, pycA, cisY) or GHB (blcAB, pckA, eno, gpsA) as a carbon source. While sucrose assimilation involved the Entner-Doudoroff and tricarboxylic acid (TCA) pathways, GHB degradation required the blc genes, TCA cycle, and gluconeogenesis. The tumor-enriched metabolite pyruvate is at the node connecting these pathways. Using reverse genetics, we showed that the blc, pckA, and pycA loci were important for aggressiveness (tumor weight), proliferation (bacterial charge), and/or fitness (competition between the constructed mutants and wild-type) of A. tumefaciens in plant tumors. This work highlighted how a biotroph mobilizes its central metabolism for exploiting a wide diversity of resources in a plant host. It further shows the complementarity of functional genome-wide scans by transcriptomics and Tn-seq to decipher the lifestyle of a plant pathogen.
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Affiliation(s)
- Almudena Gonzalez-Mula
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Joy Lachat
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Léo Mathias
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Delphine Naquin
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Florian Lamouche
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Peter Mergaert
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Denis Faure
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA University Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
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Gao T, Ding M, Yang CH, Fan H, Chai Y, Li Y. The phosphotransferase system gene ptsH plays an important role in MnSOD production, biofilm formation, swarming motility, and root colonization in Bacillus cereus 905. Res Microbiol 2018; 170:86-96. [PMID: 30395927 DOI: 10.1016/j.resmic.2018.10.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/24/2018] [Accepted: 10/23/2018] [Indexed: 12/30/2022]
Abstract
The rhizosphere bacterium Bacillus cereus 905 is capable of promoting plant growth through effective colonization on plant roots. The sodA2-encoding manganese-containing superoxide dismutase (MnSOD2) is important for survival of B. cereus 905 in the wheat rhizosphere. However, the genes involved in regulating sodA2 expression and the mechanisms of rhizosphere colonization of B. cereus 905 are not well elucidated. In this study, we found that the deletion of the ptsH gene, which encodes the histidine-phosphorylatable protein (HPr), a component of the phosphotransferase system (PTS), causes a decrease of about 60% in the MnSOD2 expression. Evidences indicate that the ptsH dramatically influences resistance to oxidative stress, glucose uptake, as well as biofilm formation and swarming motility of B. cereus 905. Root colonization assay demonstrated that ΔptsH is defective in colonizing wheat roots, while complementation of the sodA2 gene could partially restore the ability in utilization of arabinose, a non-PTS sugar, and root colonization caused by the loss of the ptsH gene. In toto, based on the current findings, we propose that PtsH contributes to root colonization of B. cereus 905 through multiple indistinct mechanisms, involving PTS and uptake of PTS-sugars, up-regulation of MnSOD2 production, and promotion of biofilm formation and swarming motility.
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Affiliation(s)
- Tantan Gao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China; Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193, China; Department of Biology, Northeastern University, 360 Huntington Avenue, Boston, MA, 02215, USA.
| | - Mingzheng Ding
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193, China.
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, 53211, USA.
| | - Haiyan Fan
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193, China.
| | - Yunrong Chai
- Department of Biology, Northeastern University, 360 Huntington Avenue, Boston, MA, 02215, USA.
| | - Yan Li
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193, China.
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8
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Tang G, Li Q, Xing S, Li N, Tang Z, Yu L, Yan J, Li X, Luo L. The LsrB Protein Is Required for Agrobacterium tumefaciens Interaction with Host Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:951-961. [PMID: 29547354 DOI: 10.1094/mpmi-02-18-0041-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Agrobacterium tumefaciens infects and causes crown galls in dicot plants by transferring T-DNA from the Ti plasmid to the host plant via a type IV secretion system. This process requires appropriate environmental conditions, certain plant secretions, and bacterial regulators. In our previous work, a member of the LysR family of transcriptional regulators (LsrB) in Sinorhizobium meliloti was found to modulate its symbiotic interactions with the host plant alfalfa. However, the function of its homolog in A. tumefaciens remains unclear. In this study, we show that the LsrB protein of A. tumefaciens is required for efficient transformation of host plants. A lsrB deletion mutant of A. tumefaciens exhibits a number of defects, including in succinoglycan production, attachment, and resistance to oxidative stress and iron limitation. RNA-sequencing analysis indicated that 465 genes were significantly differentially expressed (upregulation of 162 genes and downregulation of 303 genes) in the mutant, compared with the wild-type strain, including those involved in succinoglycan production, iron transporter, and detoxification enzymes for oxidative stress. Moreover, expression of the lsrB gene from S. meliloti, Brucella abortus, or A. tumefaciens rescued the defects observed in the S. meliloti or A. tumefaciens lsrB deletion mutant. Our findings suggest that a conserved mechanism of LsrB function exists in symbiotic and pathogenic bacteria of the family Rhizobiaceae.
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Affiliation(s)
- Guirong Tang
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
- 2 School of Communication & Information Engineering, Shanghai University; and
| | - Qiong Li
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Shenghui Xing
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Ningning Li
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Zheng Tang
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Liangliang Yu
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Junhui Yan
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Xuan Li
- 3 Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Li Luo
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
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9
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Schatzman SS, Culotta VC. Chemical Warfare at the Microorganismal Level: A Closer Look at the Superoxide Dismutase Enzymes of Pathogens. ACS Infect Dis 2018. [PMID: 29517910 DOI: 10.1021/acsinfecdis.8b00026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Superoxide anion radical is generated as a natural byproduct of aerobic metabolism but is also produced as part of the oxidative burst of the innate immune response design to kill pathogens. In living systems, superoxide is largely managed through superoxide dismutases (SODs), families of metalloenzymes that use Fe, Mn, Ni, or Cu cofactors to catalyze the disproportionation of superoxide to oxygen and hydrogen peroxide. Given the bursts of superoxide faced by microbial pathogens, it comes as no surprise that SOD enzymes play important roles in microbial survival and virulence. Interestingly, microbial SOD enzymes not only detoxify host superoxide but also may participate in signaling pathways that involve reactive oxygen species derived from the microbe itself, particularly in the case of eukaryotic pathogens. In this Review, we will discuss the chemistry of superoxide radicals and the role of diverse SOD metalloenzymes in bacterial, fungal, and protozoan pathogens. We will highlight the unique features of microbial SOD enzymes that have evolved to accommodate the harsh lifestyle at the host-pathogen interface. Lastly, we will discuss key non-SOD superoxide scavengers that specific pathogens employ for defense against host superoxide.
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Affiliation(s)
- Sabrina S. Schatzman
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Pubic Health, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, Maryland 21205, United States
| | - Valeria C. Culotta
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Pubic Health, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, Maryland 21205, United States
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10
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Zozaya-Valdés E, Roth-Schulze AJ, Egan S, Thomas T. Microbial community function in the bleaching disease of the marine macroalgae Delisea pulchra. Environ Microbiol 2017; 19:3012-3024. [PMID: 28419766 DOI: 10.1111/1462-2920.13758] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/07/2017] [Indexed: 01/10/2023]
Abstract
Disease is increasingly viewed as a major factor impacting the health of both natural and cultured populations of marine organisms, including macroalgae. The red macroalga Delisea pulchra suffers from a bleaching disease resulting from host stress and infection by opportunistic bacterial pathogens. However, how pathogens cause the disease and how the entire macro algal-associated community is involved in the process is unclear. Here, we perform a metagenomic analysis of microbial communities associated with diseased and healthy D. pulchra across multiple bleaching events. Analysis of reconstructed 16S rRNA gene sequences showed that bacteria belonging to the families Rhodobacteraceae, Saprospiraceae and Flavobacteriaceae, including bacteria previously implicated in algal bleaching, to be enriched in diseased D. pulchra. Genes with predicted functions related to chemotaxis, motility, oxidative stress response, vitamin biosynthesis and nutrient acquisition were also prevalent in microbiomes of bleached algae, which may have a role in pathogenicity. Reconstruction of genomes that were abundant on bleached samples revealed that no single organism contains all bleaching-enriched functional genes. This observation indicates that potential virulence traits are distributed across multiple bacteria and that the disease in D. pulchra may result from a consortium of opportunistic pathogens, analogous to dysbiotic or polymicrobial diseases.
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Affiliation(s)
- Enrique Zozaya-Valdés
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Alexandra J Roth-Schulze
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Suhelen Egan
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Torsten Thomas
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
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11
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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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12
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Leonard S, Hommais F, Nasser W, Reverchon S. Plant-phytopathogen interactions: bacterial responses to environmental and plant stimuli. Environ Microbiol 2017; 19:1689-1716. [DOI: 10.1111/1462-2920.13611] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 11/09/2016] [Accepted: 11/16/2016] [Indexed: 01/06/2023]
Affiliation(s)
- Simon Leonard
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - Florence Hommais
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - William Nasser
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - Sylvie Reverchon
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
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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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Regulation of the Cobalt/Nickel Efflux Operon dmeRF in Agrobacterium tumefaciens and a Link between the Iron-Sensing Regulator RirA and Cobalt/Nickel Resistance. Appl Environ Microbiol 2016; 82:4732-4742. [PMID: 27235438 DOI: 10.1128/aem.01262-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 05/20/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The Agrobacterium tumefaciens C58 genome harbors an operon containing the dmeR (Atu0890) and dmeF (Atu0891) genes, which encode a transcriptional regulatory protein belonging to the RcnR/CsoR family and a metal efflux protein belonging to the cation diffusion facilitator (CDF) family, respectively. The dmeRF operon is specifically induced by cobalt and nickel, with cobalt being the more potent inducer. Promoter-lacZ transcriptional fusion, an electrophoretic mobility shift assay, and DNase I footprinting assays revealed that DmeR represses dmeRF transcription through direct binding to the promoter region upstream of dmeR A strain lacking dmeF showed increased accumulation of intracellular cobalt and nickel and exhibited hypersensitivity to these metals; however, this strain displayed full virulence, comparable to that of the wild-type strain, when infecting a Nicotiana benthamiana plant model under the tested conditions. Cobalt, but not nickel, increased the expression of many iron-responsive genes and reduced the induction of the SoxR-regulated gene sodBII Furthermore, control of iron homeostasis via RirA is important for the ability of A. tumefaciens to cope with cobalt and nickel toxicity. IMPORTANCE The molecular mechanism of the regulation of dmeRF transcription by DmeR was demonstrated. This work provides evidence of a direct interaction of apo-DmeR with the corresponding DNA operator site in vitro The recognition site for apo-DmeR consists of 10-bp AT-rich inverted repeats separated by six C bases (5'-ATATAGTATACCCCCCTATAGTATAT-3'). Cobalt and nickel cause DmeR to dissociate from the dmeRF promoter, which leads to expression of the metal efflux gene dmeF This work also revealed a connection between iron homeostasis and cobalt/nickel resistance in A. tumefaciens.
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Branco R, Morais PV. Two superoxide dismutases from TnOtchr are involved in detoxification of reactive oxygen species induced by chromate. BMC Microbiol 2016; 16:27. [PMID: 26944876 PMCID: PMC4779226 DOI: 10.1186/s12866-016-0648-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 02/29/2016] [Indexed: 11/29/2022] Open
Abstract
Background Superoxide dismutases (SOD) have been reported as the most relevant bacterial enzymes involved in cells protection from reactive oxygen species (ROS). These toxic species are often the product of heavy metal stress. Results Two genes, chrC and chrF, from TnOtchr genetic determinant of strain Ochrobactrum tritici 5bvl1 were cloned in Escherichia coli in order to overexpress the respective proteins. Both proteins were purified and characterized as superoxide dismutases. ChrC was confirmed as being a Fe-SOD, and the enzymatic activity of the ChrF, not inhibited by hydrogen peroxide or potassium cyanide, suggested its inclusion in the Mn-SOD family. This identification was supported by chemical quantification of total metal content in purified enzyme. Both enzymes showed a maximum activity between pH 7.2-7.5. ChrF retained nearly full activity over a broader range of pH and was slightly more thermostable than ChrC. The genes encoding these enzymes in strain O. tritici 5bvl1 were inactivated, developing single and double mutants, to understand the contribution of these enzymes in detoxification mechanism of reactive oxygen species induced by chromate. During chromate stress, assays using fluorescent dyes indicated an increase of these toxic compounds in chrC, chrF and chrC/chrF mutant cells. Conclusions In spite of the multiple genes coding for putative superoxide dismutase enzymes detected in the genome of O. tritici 5bvl1, the ChrC and ChrF might help the strain to decrease the levels of reactive oxygen species in cells.
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Affiliation(s)
- Rita Branco
- CEMUC-Department of Mechanical Engineering, University of Coimbra, 3030-788, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, 3001-401, Coimbra, Portugal.
| | - Paula V Morais
- CEMUC-Department of Mechanical Engineering, University of Coimbra, 3030-788, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, 3001-401, Coimbra, Portugal.
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16
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Discrete Responses to Limitation for Iron and Manganese in Agrobacterium tumefaciens: Influence on Attachment and Biofilm Formation. J Bacteriol 2015; 198:816-29. [PMID: 26712936 DOI: 10.1128/jb.00668-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 12/13/2015] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED Transition metals such as iron and manganese are crucial trace nutrients for the growth of most bacteria, functioning as catalytic cofactors for many essential enzymes. Dedicated uptake and regulatory systems have evolved to ensure their acquisition for growth, while preventing toxicity. Transcriptomic analysis of the iron- and manganese-responsive regulons of Agrobacterium tumefaciens revealed that there are discrete regulatory networks that respond to changes in iron and manganese levels. Complementing earlier studies, the iron-responsive gene network is quite large and includes many aspects of iron-dependent metabolism and the iron-sparing response. In contrast, the manganese-responsive network is restricted to a limited number of genes, many of which can be linked to transport and utilization of the transition metal. Several of the target genes predicted to drive manganese uptake are required for growth under manganese-limited conditions, and an A. tumefaciens mutant with a manganese transport deficiency is attenuated for plant virulence. Iron and manganese limitation independently inhibit biofilm formation by A. tumefaciens, and several candidate genes that could impact biofilm formation were identified in each regulon. The biofilm-inhibitory effects of iron and manganese do not rely on recognized metal-responsive transcriptional regulators, suggesting alternate mechanisms influencing biofilm formation. However, under low-manganese conditions the dcpA operon is upregulated, encoding a system that controls levels of the cyclic di-GMP second messenger. Mutation of this regulatory pathway dampens the effect of manganese limitation. IMPORTANCE Responses to changes in transition metal levels, such as those of manganese and iron, are important for normal metabolism and growth in bacteria. Our study used global gene expression profiling to understand the response of the plant pathogen Agrobacterium tumefaciens to changes of transition metal availability. Among the properties that are affected by both iron and manganese levels are those required for normal surface attachment and biofilm formation, but the requirement for each of these transition metals is mechanistically independent from the other.
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Srijaruskul K, Charoenlap N, Namchaiw P, Chattrakarn S, Giengkam S, Mongkolsuk S, Vattanaviboon P. Regulation by SoxR of mfsA, Which Encodes a Major Facilitator Protein Involved in Paraquat Resistance in Stenotrophomonas maltophilia. PLoS One 2015; 10:e0123699. [PMID: 25915643 PMCID: PMC4411124 DOI: 10.1371/journal.pone.0123699] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Accepted: 03/06/2015] [Indexed: 11/18/2022] Open
Abstract
Stenotrophomonas maltophilia MfsA (Smlt1083) is an efflux pump in the major facilitator superfamily (MFS). Deletion of mfsA renders the strain more susceptible to paraquat, but no alteration in the susceptibility levels of other oxidants is observed. The expression of mfsA is inducible upon challenge with redox cycling/superoxide-generating drug (paraquat, menadione and plumbagin) treatments and is directly regulated by SoxR, which is a transcription regulator and sensor of superoxide-generating agents. Analysis of mfsA expression patterns in wild-type and a soxR mutant suggests that oxidized SoxR functions as a transcription activator of the gene. soxR (smlt1084) is located in a head-to-head fashion with mfsA, and these genes share the -10 motif of their promoter sequences. Purified SoxR specifically binds to the putative mfsA promoter motifs that contain a region that is highly homologous to the consensus SoxR binding site, and mutation of the SoxR binding site abolishes binding of purified SoxR protein. The SoxR box is located between the putative -35 and -10 promoter motifs of mfsA; and this position is typical for a promoter in which SoxR acts as a transcriptional activator. At the soxR promoter, the SoxR binding site covers the transcription start site of the soxR transcript; thus, binding of SoxR auto-represses its own transcription. Taken together, our results reveal for the first time that mfsA is a novel member of the SoxR regulon and that SoxR binds and directly regulates its expression.
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Affiliation(s)
- Kriangsuk Srijaruskul
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
| | - Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Poommaree Namchaiw
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Sorayut Chattrakarn
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
| | - Suparat Giengkam
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
- Center of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
- * E-mail:
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Rudder S, Doohan F, Creevey CJ, Wendt T, Mullins E. Genome sequence of Ensifer adhaerens OV14 provides insights into its ability as a novel vector for the genetic transformation of plant genomes. BMC Genomics 2014; 15:268. [PMID: 24708309 PMCID: PMC4051167 DOI: 10.1186/1471-2164-15-268] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 03/19/2014] [Indexed: 02/19/2023] Open
Abstract
BACKGROUND Recently it has been shown that Ensifer adhaerens can be used as a plant transformation technology, transferring genes into several plant genomes when equipped with a Ti plasmid. For this study, we have sequenced the genome of Ensifer adhaerens OV14 (OV14) and compared it with those of Agrobacterium tumefaciens C58 (C58) and Sinorhizobium meliloti 1021 (1021); the latter of which has also demonstrated a capacity to genetically transform crop genomes, albeit at significantly reduced frequencies. RESULTS The 7.7 Mb OV14 genome comprises two chromosomes and two plasmids. All protein coding regions in the OV14 genome were functionally grouped based on an eggNOG database. No genes homologous to the A. tumefaciens Ti plasmid vir genes appeared to be present in the OV14 genome. Unexpectedly, OV14 and 1021 were found to possess homologs to chromosomal based genes cited as essential to A. tumefaciens T-DNA transfer. Of significance, genes that are non-essential but exert a positive influence on virulence and the ability to genetically transform host genomes were identified in OV14 but were absent from the 1021 genome. CONCLUSIONS This study reveals the presence of homologs to chromosomally based Agrobacterium genes that support T-DNA transfer within the genome of OV14 and other alphaproteobacteria. The sequencing and analysis of the OV14 genome increases our understanding of T-DNA transfer by non-Agrobacterium species and creates a platform for the continued improvement of Ensifer-mediated transformation (EMT).
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Affiliation(s)
- Steven Rudder
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Doohan
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christopher J Creevey
- Animal and Bioscience Research Department, Animal and Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland
- Current address: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3FL, UK
| | - Toni Wendt
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
- Current address: Carlsberg Research Centre, Gamle Carlsberg Vej 4-10, 1799 Copenhagen V, Denmark
| | - Ewen Mullins
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
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Sornchuer P, Namchaiw P, Kerdwong J, Charoenlap N, Mongkolsuk S, Vattanaviboon P. Copper chloride induces antioxidant gene expression but reduces ability to mediate H2O2 toxicity in Xanthomonas campestris. Microbiology (Reading) 2014; 160:458-466. [DOI: 10.1099/mic.0.072470-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Copper (Cu)-based biocides are currently used as control measures for both fungal and bacterial diseases in agricultural fields. In this communication, we show that exposure of the bacterial plant pathogen Xanthomonas campestris to nonlethal concentrations of Cu2+ ions (75 µM) enhanced expression of genes in OxyR, OhrR and IscR regulons. High levels of catalase, Ohr peroxidase and superoxide dismutase diminished Cu2+-induced gene expression, suggesting that the production of hydrogen peroxide (H2O2) and organic hydroperoxides is responsible for Cu2+-induced gene expression. Despite high expression of antioxidant genes, the CuCl2-treated cells were more susceptible to H2O2 killing treatment than the uninduced cells. This phenotype arose from lowered catalase activity in the CuCl2-pretreated cells. Thus, exposure to a nonlethal dose of Cu2+ renders X. campestris vulnerable to H2O2, even when various genes for peroxide-metabolizing enzymes are highly expressed. Moreover, CuCl2-pretreated cells are sensitive to treatment with the redox cycling drug, menadione. No physiological cross-protection response was observed in CuCl2-treated cells in a subsequent challenge with killing concentrations of an organic hydroperoxide. As H2O2 production is an important initial plant immune response, defects in H2O2 protection are likely to reduce bacterial survival in plant hosts and enhance the usefulness of copper biocides in controlling bacterial pathogens.
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Affiliation(s)
- Phornphan Sornchuer
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok 10210, Thailand
| | - Poommaree Namchaiw
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
| | - Jarunee Kerdwong
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
| | - Skorn Mongkolsuk
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
| | - Paiboon Vattanaviboon
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok 10210, Thailand
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20
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Bhubhanil S, Niamyim P, Sukchawalit R, Mongkolsuk S. Cysteine desulphurase-encoding gene sufS2 is required for the repressor function of RirA and oxidative resistance in Agrobacterium tumefaciens. MICROBIOLOGY-SGM 2013; 160:79-90. [PMID: 24194559 DOI: 10.1099/mic.0.068643-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Agrobacterium tumefaciens genome contains a cluster of genes that are predicted to encode Fe-S cluster assembly proteins, and this cluster is known as the sufS2BCDS1XA operon. sufS2 is the first gene in the operon, and it was inactivated to determine its physiological function. The sufS2 mutant exhibited a small colony phenotype, grew slower than the wild-type strain and was more sensitive to various oxidants including peroxide, organic hydroperoxide and superoxide. The sufS2 gene was negatively regulated by iron response regulator (Irr) and rhizobial iron regulator (RirA) under low and high iron conditions, respectively, and was inducible in response to oxidative stress. The oxidant-induced expression of sufS2 was controlled by Irr, RirA and an additional but not yet identified mechanism. sufS2 was required for RirA activity in the repression of a sufS2 promoter-lacZ fusion. RirA may use Fe-S as its cofactor. sufS2 disruption may cause a defect in the Fe-S supply and could thereby affect the RirA activity. The three conserved cysteine residues (C91, C99 and C105) in RirA were predicted to coordinate with the Fe-S cluster and were shown to be essential for RirA repression of the sufS2-lacZ fusion. These results suggested that sufS2 is important for the survival of A. tumefaciens.
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Affiliation(s)
- Sakkarin Bhubhanil
- Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.,Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand
| | - Phettree Niamyim
- Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.,Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand
| | - Rojana Sukchawalit
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.,Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.,Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.,Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand
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21
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Egan S, Fernandes ND, Kumar V, Gardiner M, Thomas T. Bacterial pathogens, virulence mechanism and host defence in marine macroalgae. Environ Microbiol 2013; 16:925-38. [PMID: 24112830 DOI: 10.1111/1462-2920.12288] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 09/13/2013] [Indexed: 12/26/2022]
Abstract
Macroalgae are important ecosystem engineers in temperate marine waters. The function of macroalgae is intimately linked to the composition and structure of their epibiotic bacterial, communities, and evidence has emerged that bacteria can also have a negative impact on their host by causing disease. A few examples exist where bacteria have been unambiguously linked to macroalgal disease, however in many cases, pathogenicity has not been clearly separated from saprophytic behaviour or secondary colonization after disease initiation. Nevertheless, pathogenic pressure by bacteria might be substantial, as macroalgae have evolved a range of innate and induced defence mechanism that have the potential to control bacterial attacks. The presence and abundance of virulence factors in marine bacteria, which have not previously been recognized as pathogens, also represents an underappreciated, opportunistic potential for disease. Given that virulence expression in opportunistic pathogens is often dependent on environmental conditions, we predict that current and future anthropogenic changes in the marine environment will lead to an increase in the occurrence of macroalgal disease. This review highlights important areas of research that require future attention to understand the link between environmental change, opportunistic pathogens and macroalgal health in the world's oceans.
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Affiliation(s)
- Suhelen Egan
- Centre for Marine Bio-Innovation and School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
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22
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Chiang SM, Schellhorn HE. Regulators of oxidative stress response genes in Escherichia coli and their functional conservation in bacteria. Arch Biochem Biophys 2012; 525:161-9. [PMID: 22381957 DOI: 10.1016/j.abb.2012.02.007] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 01/31/2012] [Accepted: 02/12/2012] [Indexed: 01/24/2023]
Abstract
Oxidative stress, through the production of reactive oxygen species, is a natural consequence of aerobic metabolism. Escherichia coli has several major regulators activated during oxidative stress, including OxyR, SoxRS, and RpoS. OxyR and SoxR undergo conformation changes when oxidized in the presence of hydrogen peroxide and superoxide radicals, respectively, and subsequently control the expression of cognate genes. In contrast, the RpoS regulon is induced by an increase in RpoS levels. Current knowledge regarding the activation and function of these regulators and their dependent genes in E. coli during oxidative stress forms the scope of this review. Despite the enormous genomic diversity of bacteria, oxidative stress response regulators in E. coli are functionally conserved in a wide range of bacterial groups, possibly reflecting positive selection of these regulators. SoxRS and RpoS homologs are present and respond to oxidative stress in Proteobacteria, and OxyR homologs are present and function in H(2)O(2) resistance in a range of bacteria, from gammaproteobacteria to Actinobacteria. Bacteria have developed complex, adapted gene regulatory responses to oxidative stress, perhaps due to the prevalence of reactive oxygen species produced endogenously through metabolism or due to the necessity of aerotolerance mechanisms in anaerobic bacteria exposed to oxygen.
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Affiliation(s)
- Sarah M Chiang
- Department of Biology, McMaster University, 1280 Main St. West, Life Sciences Building, Hamilton, ON, Canada L8S 4K1
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23
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Aguirre JD, Culotta VC. Battles with iron: manganese in oxidative stress protection. J Biol Chem 2012; 287:13541-8. [PMID: 22247543 DOI: 10.1074/jbc.r111.312181] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron.
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Affiliation(s)
- J Dafhne Aguirre
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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24
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Novel roles of SoxR, a transcriptional regulator from Xanthomonas campestris, in sensing redox-cycling drugs and regulating a protective gene that have overall implications for bacterial stress physiology and virulence on a host plant. J Bacteriol 2011; 194:209-17. [PMID: 22056938 DOI: 10.1128/jb.05603-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In Xanthomonas campestris pv. campestris, SoxR likely functions as a sensor of redox-cycling drugs and as a transcriptional regulator. Oxidized SoxR binds directly to its target site and activates the expression of xcc0300, a gene that has protective roles against the toxicity of redox-cycling compounds. In addition, SoxR acts as a noninducible repressor of its own expression. X. campestris pv. campestris requires SoxR both for protection against redox-cycling drugs and for full virulence on a host plant. The X. campestris model of the gene regulation and physiological roles of SoxR represents a novel variant of existing bacterial SoxR models.
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25
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Krehenbrink M, Edwards A, Downie JA. The superoxide dismutase SodA is targeted to the periplasm in a SecA-dependent manner by a novel mechanism. Mol Microbiol 2011; 82:164-79. [PMID: 21854464 DOI: 10.1111/j.1365-2958.2011.07803.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The manganese/iron-type superoxide dismutase (SodA) of Rhizobium leguminosarum bv. viciae 3841 is exported to the periplasm of R. l. bv. viciae and Escherichia coli. However, it does not possess a hydrophobic cleaved N-terminal signal peptide typically present in soluble proteins exported by the Sec-dependent (Sec) pathway or the twin-arginine translocation (TAT) pathway. A tatC mutant of R. l. bv. viciae exported SodA to the periplasm, ruling out export of SodA as a complex with a TAT substrate as a chaperone. The export of SodA was unaffected in a secB mutant of E. coli, but its export from R. l. bv. viciae was inhibited by azide, an inhibitor of SecA ATPase activity. A temperature-sensitive secA mutant of E. coli was strongly reduced for SodA export. The 10 N-terminal amino acid residues of SodA were sufficient to target the reporter protein alkaline phosphatase to the periplasm. Our results demonstrate the export of a protein lacking a classical signal peptide to the periplasm by a SecA-dependent, but SecB-independent targeting mechanism. Export of the R. l. bv. viciae SodA to the periplasm was not limited to the genus Rhizobium, but was also observed in other proteobacteria.
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Affiliation(s)
- Martin Krehenbrink
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR47UH, UK
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Flores-Cruz Z, Allen C. Necessity of OxyR for the hydrogen peroxide stress response and full virulence in Ralstonia solanacearum. Appl Environ Microbiol 2011; 77:6426-32. [PMID: 21803891 PMCID: PMC3187169 DOI: 10.1128/aem.05813-11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 07/21/2011] [Indexed: 01/10/2023] Open
Abstract
The plant pathogen Ralstonia solanacearum, which causes bacterial wilt disease, is exposed to reactive oxygen species (ROS) during tomato infection and expresses diverse oxidative stress response (OSR) genes during midstage disease on tomato. The R. solanacearum genome predicts that the bacterium produces multiple and redundant ROS-scavenging enzymes but only one known oxidative stress response regulator, OxyR. An R. solanacearum oxyR mutant had no detectable catalase activity, did not grow in the presence of 250 μM hydrogen peroxide, and grew poorly in the oxidative environment of solid rich media. This phenotype was rescued by the addition of exogenous catalase, suggesting that oxyR is essential for the hydrogen peroxide stress response. Unexpectedly, the oxyR mutant strain grew better than the wild type in the presence of the superoxide generator paraquat. Gene expression studies indicated that katE, kaG, ahpC1, grxC, and oxyR itself were each differentially expressed in the oxyR mutant background and in response to hydrogen peroxide, suggesting that oxyR is necessary for hydrogen peroxide-inducible gene expression. Additional OSR genes were differentially regulated in response to hydrogen peroxide alone. The virulence of the oxyR mutant strain was significantly reduced in both tomato and tobacco host plants, demonstrating that R. solanacearum is exposed to inhibitory concentrations of ROS in planta and that OxyR-mediated responses to ROS during plant pathogenesis are important for R. solanacearum host adaptation and virulence.
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Affiliation(s)
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin—Madison, Madison, Wisconsin 53706
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Abstract
Singlet oxygen is one of several reactive oxygen species that can destroy biomolecules, microorganisms and other cells. Traditionally, the response to singlet oxygen has been termed photo-oxidative stress, as light-dependent processes in photosynthetic cells are major biological sources of singlet oxygen. Recent work identifying a core set of singlet oxygen stress response genes across various bacterial species highlights the importance of this response for survival by both photosynthetic and non-photosynthetic cells. Here, we review how bacterial cells mount a transcriptional response to photo-oxidative stress in the context of what is known about bacterial stress responses to other reactive oxygen species.
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Affiliation(s)
- Eva C Ziegelhoffer
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Drive, Madison, Wisconsin 53706, USA
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28
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The catalase-peroxidase KatG is required for virulence of Xanthomonas campestris pv. campestris in a host plant by providing protection against low levels of H2O2. J Bacteriol 2009; 191:7372-7. [PMID: 19783631 DOI: 10.1128/jb.00788-09] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Xanthomonas campestris pv. campestris katG encodes a catalase-peroxidase that has a role in protecting the bacterium against micromolar concentrations of H(2)O(2). A knockout mutation in katG that causes loss of catalase-peroxidase activity correlates with increased susceptibility to H(2)O(2) and a superoxide generator and is avirulent in a plant model system. katG expression is induced by oxidants in an OxyR-dependent manner.
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Flores-Cruz Z, Allen C. Ralstonia solanacearum encounters an oxidative environment during tomato infection. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:773-82. [PMID: 19522559 DOI: 10.1094/mpmi-22-7-0773] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Ralstonia solanacearum genes that are induced during tomato infection suggested that this pathogen encounters reactive oxygen species (ROS) during bacterial wilt pathogenesis. The genomes of R. solanacearum contain multiple redundant ROS-scavenging enzymes, indirect evidence that this pathogen experiences intense oxidative stress during its life cycle. Over 9% of the bacterium's plant-induced genes were also upregulated by hydrogen peroxide in culture, suggesting that oxidative stress may be linked to life in the plant host. Tomato leaves infected by R. solanacearum contained hydrogen peroxide, and concentrations of this ROS increased as pathogen populations increased. Mutagenesis of a plant-induced predicted peroxidase gene, bcp, resulted in an R. solanacearum strain with reduced ability to detoxify ROS in culture. The bcp mutant caused slightly delayed bacterial wilt disease onset in tomato. Moreover, its virulence was significantly reduced on tobacco plants engineered to overproduce hydrogen peroxide, demonstrating that Bcp is necessary for detoxification of plant-derived hydrogen peroxide and providing evidence that host ROS can limit the success of this pathogen. These results reveal that R. solanacearum is exposed to ROS during pathogenesis and that it has evolved a redundant and efficient oxidative stress response to adapt to the host environment and cause disease.
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Affiliation(s)
- Zomary Flores-Cruz
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Functional and expression analyses of the cop operon, required for copper resistance in Agrobacterium tumefaciens. J Bacteriol 2009; 191:5159-68. [PMID: 19502402 DOI: 10.1128/jb.00384-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The copper resistance determinant copARZ, which encodes a CPx-type copper ATPase efflux protein, a transcriptional regulator, and a putative intracellular copper chaperone, was functionally characterized for the phytopathogenic bacterium Agrobacterium tumefaciens. These genes are transcribed as an operon, and their expression is induced in response to increasing copper and silver ion concentrations in a copR-dependent fashion. Analysis of the copARZ promoter revealed a putative CopR binding box located within the spacer of the -35 and -10 promoter motifs. In vitro, purified CopR could specifically bind to the box. The inactivation of the copARZ operon or copZ reduces the level of resistance to copper but not to other metal ions. Also, the copARZ operon mutant shows increased sensitivity to the superoxide generators menadione and plumbagin. In addition, the loss of functional copZ does not affect the ability of copper ions to induce the copARZ promoter, indicating that CopZ is not involved in the copper-sensing mechanism of CopR. Altogether, the results demonstrate a crucial role for the copARZ operon as a component of the copper resistance machinery in A. tumefaciens.
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Tanboon W, Chuchue T, Vattanaviboon P, Mongkolsuk S. Inactivation of thioredoxin-like gene alters oxidative stress resistance and reduces cytochromecoxidase activity inAgrobacterium tumefaciens. FEMS Microbiol Lett 2009; 295:110-6. [DOI: 10.1111/j.1574-6968.2009.01591.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Saenkham P, Vattanaviboon P, Mongkolsuk S. Mutation inscoaffects cytochromecassembly and alters oxidative stress resistance inAgrobacterium tumefaciens. FEMS Microbiol Lett 2009; 293:122-9. [DOI: 10.1111/j.1574-6968.2009.01516.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Ngok-Ngam P, Ruangkiattikul N, Mahavihakanont A, Virgem SS, Sukchawalit R, Mongkolsuk S. Roles of Agrobacterium tumefaciens RirA in iron regulation, oxidative stress response, and virulence. J Bacteriol 2009; 191:2083-90. [PMID: 19168612 PMCID: PMC2655498 DOI: 10.1128/jb.01380-08] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 01/09/2009] [Indexed: 12/26/2022] Open
Abstract
The analysis of genetics and physiological functions of Agrobacterium tumefaciens RirA (rhizobial iron regulator) has shown that it is a transcription regulator and a repressor of iron uptake systems. The rirA mutant strain (NTLrirA) overproduced siderophores and exhibited a highly constitutive expression of genes involved in iron uptake (fhuA, irp6A, and fbpA) compared to that of the wild-type strain (NTL4). The deregulation in the iron control of iron uptake in NTLrirA led to iron overload in the cell, which was supported by the observation that the NTLrirA mutant was more sensitive than wild-type NTL4 to an iron-activated antibiotic, streptonigrin. The NTLrirA mutant was more sensitive than the parental strain to oxidants, including hydrogen peroxide, organic hydroperoxide, and a superoxide generator, menadione. However, the addition of an iron chelator, 2,2'-dipyridyl, reversed the mutant hypersensitivity to H(2)O(2) and organic hydroperoxide, indicating the role of iron in peroxide toxicity. Meanwhile, the reduced level of superoxide dismutase (SodBIII) was partly responsible for the menadione-sensitive phenotype of the NTLrirA mutant. The NTLrirA mutant showed a defect in tumorigenesis on tobacco leaves, which likely resulted from the increased sensitivity of NTLrirA to oxidants and the decreased ability of NTLrirA to induce virulence genes (virB and virE). These data demonstrated that RirA is important for A. tumefaciens during plant-pathogen interactions.
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Saenkham P, Utamapongchai S, Vattanaviboon P, Mongkolsuk S. Agrobacterium tumefaciens iron superoxide dismutases have protective roles against singlet oxygen toxicity generated from illuminated Rose Bengal. FEMS Microbiol Lett 2009; 289:97-103. [PMID: 19054099 DOI: 10.1111/j.1574-6968.2008.01382.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Singlet oxygen is a highly reactive form of molecular oxygen that is harmful to biological systems. Here, the role of three iron-containing superoxide dismutase (sodB) genes is clearly shown in protecting Agrobacterium tumefaciens against singlet oxygen toxicity. A sodBI mutant was more sensitive to singlet oxygen than both wild-type bacteria and a double sodBII-sodBIII mutant strain. Moreover, a sodBI-sodBII double mutant had higher sensitivity to singlet oxygen than a single sodBI mutant, although the double mutant was comparable to a sodB null mutant. High-level expression of sodBI and sodBII fully complemented the singlet oxygen hypersensitivity phenotype of the sodB null mutant, while high-level expression of sodBIII encoding a periplasmic SOD only partially restored the phenotype. Taken together, our data suggest that SodBI and SodBII have novel protective roles against singlet oxygen toxicity through unknown mechanisms.
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Affiliation(s)
- Panatda Saenkham
- Department of Biotechnology, Faculty of Science, Chulabhorn Research Institute, Lak Si, Bangkok, Thailand
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35
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Lee LY, Gelvin SB. T-DNA binary vectors and systems. PLANT PHYSIOLOGY 2008; 146:325-32. [PMID: 18250230 PMCID: PMC2245830 DOI: 10.1104/pp.107.113001] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 11/25/2007] [Indexed: 05/22/2023]
Affiliation(s)
- Lan-Ying Lee
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA
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