scholarly journals OxyR and SoxR Modulate the Inducible Oxidative Stress Response and Are Implicated During Different Stages of Infection for the Bacterial Phytopathogen Pantoea stewartii subsp. stewartii

2014 ◽  
Vol 27 (5) ◽  
pp. 479-490 ◽  
Author(s):  
Lindsey Burbank ◽  
M. Caroline Roper
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Stress Response ◽  
Plant Pathogens ◽  
Sweet Corn ◽  
Bacterial Pathogen ◽  
Infection Process ◽  
Pantoea Stewartii ◽  
Hydrogen Peroxide Treatment ◽  
Stewart's Wilt

Reactive oxygen species (ROS) from a variety of sources are often encountered by invading plant pathogens during the infection process. Pantoea stewartii subsp. stewartii, the etiological agent of Stewart's wilt, is a serious bacterial pathogen of sweet corn that colonizes both the apoplast and xylem tissues in which ROS are produced. The P. stewartii genome predicts the presence of two redox-sensing transcriptional regulators, OxyR and SoxR, which both activate gene expression in response to oxidative stress. ROS exposure in the form of hydrogen peroxide and the superoxide-generating compound paraquat initiates an induced stress response through OxyR and SoxR that includes activation of the ROS-detoxifying enzymes alkyl hydroperoxide reductase and superoxide dismutase. P. stewartii ΔsoxR was more sensitive to paraquat and was compromised in the ability to form water-soaked lesions, while ΔoxyR was more sensitive to hydrogen peroxide treatment and was deficient in exopolysaccharide production and the elicitation of wilting symptoms. This demonstrates that both SoxR and OxyR play an important role in virulence in the different niches that P. stewartii colonize during the infection process.

scholarly journals Siderophore-Mediated Iron Acquisition Influences Motility and Is Required for Full Virulence of the Xylem-Dwelling Bacterial Phytopathogen Pantoea stewartii subsp. stewartii

2014 ◽  
Vol 81 (1) ◽  
pp. 139-148 ◽  
Author(s):  
Lindsey Burbank ◽  
Mojtaba Mohammadi ◽  
M. Caroline Roper
Keyword(s):  
Sweet Corn ◽  
Iron Acquisition ◽  
Bacterial Pathogen ◽  
Biosynthetic Gene Cluster ◽  
In Planta ◽  
Content Type ◽  
Pantoea Stewartii ◽  
Active Iron ◽  
Stewart's Wilt ◽  
Chelating Compounds

ABSTRACTIron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form.Pantoeastewartiisubsp.stewartii, the causal agent of Stewart's wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by theiucABCD-iutAoperon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations iniucAandiutAresulted in a decrease in surface-based motility thatP. stewartiiutilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility forP. stewartii. Furthermore, bacterial movementin plantais also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen.

scholarly journals A Large Repetitive RTX-Like Protein Mediates Water-Soaked Lesion Development, Leakage of Plant Cell Content and Host Colonization in the Pantoea stewartii subsp. stewartii Pathosystem

2015 ◽  
Vol 28 (12) ◽  
pp. 1374-1382 ◽  
Author(s):  
M. Caroline Roper ◽  
Lindsey P. Burbank ◽  
Kayla Williams ◽  
Polrit Viravathana ◽  
Hsin-Yu Tien ◽  
...  
Keyword(s):  
Sweet Corn ◽  
Bacterial Pathogen ◽  
Large Family ◽  
Host Cells ◽  
Gene Encoding ◽  
Cell Content ◽  
Pantoea Stewartii ◽  
Rtx Toxins ◽  
Potential Factors ◽  
Stewart's Wilt

Pantoea stewartii subsp. stewartii is the etiological agent of Stewart’s wilt and is a serious bacterial pathogen affecting sweet corn. During the leaf blight phase, P. stewartii colonizes the leaf apoplast and causes a characteristic water-soaked lesion. The Hrp type III secretion system has been implicated in the water-soaking phenotype, and the goal of this study was to investigate other potential factors that contribute to the plant cellular disruption associated with these lesions. The P. stewartii genome contains a gene encoding a large repetitive RTX toxin, designated rtx2. RTX toxins comprise a large family of pore-forming proteins, which are widely distributed among gram-negative bacteria. These cytotoxins usually lyse their target host cells and cause significant tissue damage as a consequence. We hypothesized that this RTX-like toxin plays a role in the water-soaking phase of infection due to its predicted cytolytic properties. Based on the data reported here, we conclude that RTX2 contributes significantly to the development of water-soaked lesions and leakage of plant cellular contents and is an important pathogenicity factor for P. stewartii.

TheahpDgene ofCorynebacterium glutamicumplays an important role in hydrogen peroxide-induced oxidative stress response

2018 ◽  
Vol 165 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Eun-Ji Hong ◽  
Haeri Jeong ◽  
Dong-Seok Lee ◽  
Younhee Kim ◽  
Heung-Shick Lee
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Stress Response ◽  
Oxidative Stress Response

scholarly journals SodA Contributes to the Virulence of Avian PathogenicEscherichia coliO2 Strain E058 in Experimentally Infected Chickens

2019 ◽  
Vol 201 (6) ◽  
Author(s):  
Qingqing Gao ◽  
Le Xia ◽  
Xiaobo Wang ◽  
Zhengqin Ye ◽  
Jinbiao Liu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Virulence Factor ◽  
Infection Process ◽  
Strain Identification ◽  
Bacterial Disease ◽  
Wild Type ◽  
Content Type

ABSTRACTStrains of avian pathogenicEscherichia coli(APEC), the common pathogen of avian colibacillosis, encounter reactive oxygen species (ROS) during the infection process. Superoxide dismutases (SODs), acting as antioxidant factors, can protect against ROS-mediated host defenses. Our previous reports showed that thesodAgene (encoding a Mn-cofactor-containing SOD [MnSOD]) is highly expressed during the septicemic infection process of APEC.sodAhas been proven to be a virulence factor of certain pathogens, but its role in the pathogenicity of APEC has not been fully identified. In this study, we deleted thesodAgene from the virulent APEC O2 strain E058 and examined thein vitroandin vivophenotypes of the mutant. ThesodAmutant was more sensitive to hydrogen peroxide in terms of both its growth and viability than was the wild type. The ability to form a biofilm was weakened in thesodAmutant. ThesodAmutant was significantly more easily phagocytosed by chicken macrophages than was the wild-type strain. Chicken infection assays revealed significantly attenuated virulence of thesodAmutant compared with the wild type at 24 h postinfection. The virulence phenotype was restored by complementation of thesodAgene. Quantitative real-time reverse transcription-PCR revealed that the inactivation ofsodAreduced the expression of oxidative stress response geneskatE,perR, andosmCbut did not affect the expression ofsodBandsodC. Taken together, our studies indicate that SodA is important for oxidative resistance and virulence of APEC E058.IMPORTANCEAvian colibacillosis, caused by strains of avian pathogenicEscherichia coli, is a major bacterial disease of severe economic significance to the poultry industry worldwide. The virulence mechanisms of APEC are not completely understood. This study investigated the influence of an antioxidant protein, SodA, on the phenotype and pathogenicity of APEC O2 strain E058. This is the first report demonstrating that SodA plays an important role in protecting a specific APEC strain against hydrogen peroxide-induced oxidative stress and contributes to the virulence of this pathotype strain. Identification of this virulence factor will enhance our knowledge of APEC pathogenic mechanisms, which is crucial for designing successful strategies against associated infections and transmission.

scholarly journals Oxidative stress response ofInonotus obliquusinduced by hydrogen peroxide

2009 ◽  
Vol 47 (8) ◽  
pp. 814-823 ◽  
Author(s):  
Weifa Zheng ◽  
Yanxia Zhao ◽  
Meimei Zhang ◽  
Zhiwen Wei ◽  
Kangjie Miao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Stress Response ◽  
Oxidative Stress Response

Further investigation of the mechanism of Vitreoscilla hemoglobin (VHb) protection from oxidative stress in Escherichia coli

Biologia ◽  
2011 ◽  
Vol 66 (5) ◽  
Author(s):  
Meltem Akbas ◽  
Tugrul Doruk ◽  
Serhat Ozdemir ◽  
Benjamin Stark
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Stationary Phase ◽  
Exponential Phase ◽  
Vitreoscilla Hemoglobin ◽  
Sod Activity ◽  
E Coli ◽  
Hydrogen Peroxide Treatment

AbstractIn Escherichia coli, Vitreoscilla hemoglobin (VHb) protects against oxidative stress, perhaps, in part, by oxidizing OxyR. Here this protection, specifically VHb-associated effects on superoxide dismutase (SOD) and catalase levels, was examined. Exponential or stationary phase cultures of SOD+ or SOD− E. coli strains with or without VHb and oxyR antisense were treated with 2 mM hydrogen peroxide without sublethal peroxide induction, and compared to untreated control cultures. The hydrogen peroxide treatment was toxic to both SOD+ and SOD− cells, but much more to SOD− cells; expression of VHb in SOD+ strains enhanced this toxicity. In contrast, the presence of VHb was generally associated in the SOD+ background with a modest increase in SOD activity that was not greatly affected by oxyR antisense or peroxide treatment. In both SOD+ and SOD− backgrounds, VHb was associated with higher catalase activity both in the presence and absence of peroxide. Contrary to its stimulatory effects in stationary phase, in exponential phase oxyR antisense generally decreased VHb levels.

Oxidative stress response of Inonotus obliquus induced by hydrogen peroxide

2009 ◽  
pp. 1-10 ◽  
Author(s):  
Weifa Zheng ◽  
Yanxia Zhao ◽  
Meimei Zhang ◽  
Zhiwen Wei ◽  
Kangjie Miao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Inonotus Obliquus

scholarly journals Necessity of OxyR for the Hydrogen Peroxide Stress Response and Full Virulence in Ralstonia solanacearum

2011 ◽  
Vol 77 (18) ◽  
pp. 6426-6432 ◽  
Author(s):  
Zomary Flores-Cruz ◽  
Caitilyn Allen
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Hydrogen Peroxide ◽  
Stress Response ◽  
Mutant Strain ◽  
Ralstonia Solanacearum ◽  
Oxidative Stress Response ◽  
Ros Scavenging ◽  
Content Type ◽  
Peroxide Stress

ABSTRACTThe plant pathogenRalstonia 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. TheR. solanacearumgenome predicts that the bacterium produces multiple and redundant ROS-scavenging enzymes but only one known oxidative stress response regulator, OxyR. AnR. solanacearumoxyRmutant 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 thatoxyRis essential for the hydrogen peroxide stress response. Unexpectedly, theoxyRmutant strain grew better than the wild type in the presence of the superoxide generator paraquat. Gene expression studies indicated thatkatE,kaG,ahpC1,grxC, andoxyRitself were each differentially expressed in theoxyRmutant background and in response to hydrogen peroxide, suggesting thatoxyRis necessary for hydrogen peroxide-inducible gene expression. Additional OSR genes were differentially regulated in response to hydrogen peroxide alone. The virulence of theoxyRmutant strain was significantly reduced in both tomato and tobacco host plants, demonstrating thatR. solanacearumis exposed to inhibitory concentrations of ROSin plantaand that OxyR-mediated responses to ROS during plant pathogenesis are important forR. solanacearumhost adaptation and virulence.

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