OhrR, a transcription repressor that senses and responds to changes in organic peroxide levels in <i>Xanthomonas campestris</i> pv. <i>phaseoli</i>

Panmanee, Warunya; Vattanaviboon, Paiboon; Eiamphungporn, Warawan; Whangsuk, Wirongrong; Sallabhan, Ratiboot; Mongkolsuk, Skorn

doi:10.1046/j.1365-2958.2002.03116.x

Cited by 59 publications

(74 citation statements)

References 25 publications

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“…A. tumefaciens and X. campestris pv. phaseoli OhrRs each contain a cysteine (Cys) residue at position 21 that is absolutely conserved among all OhrRs and has been shown to be required for sensing organic hydroperoxide (11,25 4A). …”

Section: Resultsmentioning

confidence: 99%

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ohrR and ohr Are the Primary Sensor/Regulator and Protective Genes against Organic Hydroperoxide Stress in Agrobacterium tumefaciens

et al. 2006

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The genes involved in organic hydroperoxide protection in Agrobacterium tumefaciens were functionally evaluated. Gene inactivation studies and functional analyses have identified ohr, encoding a thiol peroxidase, as the gene primarily responsible for organic hydroperoxide protection in A. tumefaciens. An ohr mutant was sensitive to organic hydroperoxide killing and had a reduced capacity to metabolize organic hydroperoxides. ohr is located next to, and is divergently transcribed from, ohrR, encoding a sensor and transcription regulator of organic hydroperoxide stress. Transcription of both ohr and ohrR was induced by exposure to organic hydroperoxides but not by exposure to other oxidants. This induction required functional ohrR. The results of gel mobility shift and DNase I footprinting assays with purified OhrR, combined with in vivo promoter deletion analyses, confirmed that OhrR regulated both ohrR and ohr by binding to a single OhrR binding box that overlapped the ohrR and ohr promoters. ohrR and ohr are both required for the establishment of a novel cumene hydroperoxide-induced adaptive response. Inactivation or overexpression of other Prx family genes (prx1, prx2, prx3, bcp1, and bcp2) did not affect either the resistance to, or the ability to degrade, organic hydroperoxide. Taken together, the results of biochemical, gene regulation and physiological studies support the role of ohrR and ohr as the primary system in sensing and protecting A. tumefaciens from organic hydroperoxide stress.

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Section: Resultsmentioning

confidence: 99%

“…The total protein concentration was determined for each of the cleared lysates prior to their use in enzyme assays. ␤-Galactosidase was assayed as described earlier (25).…”

Section: Methodsmentioning

confidence: 99%

ohrR and ohr Are the Primary Sensor/Regulator and Protective Genes against Organic Hydroperoxide Stress in Agrobacterium tumefaciens

et al. 2006

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“…Only C22 and C127 are essential for regulator function (85,86). Initial oxidation of the sensing C22 to sulfenic acid is followed by rapid formation of an intermolecular disulfide bond with C127 of the other subunit in the dimer (Fig.…”

Section: Ohrrmentioning

confidence: 99%

Peroxide‐Sensing Transcriptional Regulators in Bacteria

Dubbs

Mongkolsuk

2016

Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria

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The ability to maintain intracellular concentrations of toxic reactive oxygen species (ROS) within safe limits is essential for all aerobic life forms. In bacteria, as well as other organisms, ROS are produced during the normal course of aerobic metabolism, necessitating the constitutive expression of ROS scavenging systems. However, bacteria can also experience transient high-level exposure to ROS derived either from external sources, such as the host defense response, or as a secondary effect of other seemingly unrelated environmental stresses. Consequently, transcriptional regulators have evolved to sense the levels of ROS and coordinate the appropriate oxidative stress response. Three well-studied examples of these are the peroxide responsive regulators OxyR, PerR, and OhrR. OxyR and PerR are sensors of primarily H 2 O 2 , while OhrR senses organic peroxide (ROOH) and sodium hypochlorite (NaOCl). OxyR and OhrR sense oxidants by means of the reversible oxidation of specific cysteine residues. In contrast, PerR senses H 2 O 2 via the Fe-catalyzed oxidation of histidine residues. These transcription regulators also influence complex biological phenomena, such as biofilm formation, the evasion of host immune responses, and antibiotic resistance via the direct regulation of specific proteins.

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“…Inactivation of ohr renders the mutant bacteria hypersensitive to organic hydroperoxides (3,25). In vivo, unlike catalase and alkyl hydroperoxide reductase, Ohr seems to have a very specific role in detoxification of organic hydroperoxides but not of H 2 O 2 (6,11,25,29). In vitro, Ohr also catalyzes H 2 O 2 degradation, albeit at a rate 20 times lower than that for the degradation of an organic hydroperoxide (7).…”

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confidence: 99%

“…It has been shown in Bacillus subtilis, Xanthomonas campestris, Agrobacterium tumefaciens, and Streptomyces coelicolor that ohr is regulated by OhrR (6,11,27,29). OhrR in Gramnegative bacteria belongs to the two-cysteine OhrR family.…”

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Analyses of the Regulatory Mechanism and Physiological Roles of Pseudomonas aeruginosa OhrR, a Transcription Regulator and a Sensor of Organic Hydroperoxides

et al. 2010

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ohrR encodes an organic hydroperoxide sensor and a transcriptional repressor that regulates organic hydroperoxide-inducible expression of a thiol peroxidase gene, ohr, and itself. OhrR binds directly to the operators and represses transcription of these genes. Exposure to an organic hydroperoxide leads to oxidation of OhrR and to subsequent structural changes that result in the loss of the repressor's ability to bind to the operators that allow expression of the target genes. Differential induction of ohrR and ohr by tert-butyl hydroperoxide suggests that factors such as the repressor's dissociation constants for different operators and the chemical nature of the inducer contribute to OhrR-dependent organic hydroperoxide-inducible gene expression. ohrR and ohr mutants show increased and decreased resistance to organic hydroproxides, respectively, compared to a parental strain. Moreover, the ohrR mutant had a reduced-virulence phenotype in the Pseudomonas aeruginosa-Caenorhabditis elegans pathogenicity model.

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OhrR, a transcription repressor that senses and responds to changes in organic peroxide levels in Xanthomonas campestris pv. phaseoli

Cited by 59 publications

References 25 publications

ohrR and ohr Are the Primary Sensor/Regulator and Protective Genes against Organic Hydroperoxide Stress in Agrobacterium tumefaciens

ohrR and ohr Are the Primary Sensor/Regulator and Protective Genes against Organic Hydroperoxide Stress in Agrobacterium tumefaciens

Peroxide‐Sensing Transcriptional Regulators in Bacteria

Analyses of the Regulatory Mechanism and Physiological Roles of Pseudomonas aeruginosa OhrR, a Transcription Regulator and a Sensor of Organic Hydroperoxides

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