24 results on '"Mongkolsuk, S."'
Search Results
2. The role of MfsR, a TetR-type transcriptional regulator, in adaptive protection of Stenotrophomonas maltophilia against benzalkonium chloride via the regulation of mfsQ.
- Author
-
Chittrakanwong J, Charoenlap N, Vanitshavit V, Sowatad A, Mongkolsuk S, and Vattanaviboon P
- Subjects
- Gene Expression Regulation, Bacterial, Membrane Transport Proteins genetics, Operon, Phylogeny, Quaternary Ammonium Compounds pharmacology, Bacterial Proteins genetics, Bacterial Proteins metabolism, Benzalkonium Compounds pharmacology, Stenotrophomonas maltophilia classification, Stenotrophomonas maltophilia drug effects, Stenotrophomonas maltophilia genetics, Stenotrophomonas maltophilia metabolism
- Abstract
A gene encoding the TetR-type transcriptional regulator mfsR is located immediately downstream of mfsQ and is transcribed in the same transcriptional unit. mfsQ encodes a major facilitator superfamily (MFS) efflux transporter contributing to the resistance of Stenotrophomonas maltophilia towards disinfectants belonging to quaternary ammonium compounds (QACs), which include benzalkonium chloride (BAC). Phylogenetic analysis revealed that MfsR is closely related to CgmR, a QAC-responsive transcriptional regulator belonging to the TetR family. MfsR regulated the expression of the mfsQR operon in a QAC-inducible manner. The constitutively high transcript level of mfsQ in an mfsR mutant indicated that MfsR functions as a transcriptional repressor of the mfsQR operon. Electrophoretic mobility shift assays showed that purified MfsR specifically bound to the putative promoter region of mfsQR, and in vitro treatments with QACs led to the release of MfsR from binding complexes. DNase I protection assays revealed that the MfsR binding box comprises inverted palindromic sequences located between motifs -35 and -10 of the putative mfsQR promoter. BAC-induced adaptive protection was abolished in the mfsR mutant and was restored in the complemented mutant. Overall, MfsR is a QACs-sensing regulator that controls the expression of mfsQ. In the absence of QACs, MfsR binds to the box located in the mfsQR promoter and represses its transcription. The presence of QACs derepresses MfsR activity, allowing RNA polymerase binding and transcription of mfsQR. This MfsR-MsfQ system enables S. maltophilia to withstand high levels of QACs., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2021
- Full Text
- View/download PDF
3. Identification of amino acid residues important for the function of Agrobacterium tumefaciens Irr protein.
- Author
-
Bhubhanil S, Ruangkiattikul N, Niamyim P, Chamsing J, Ngok-Ngam P, Sukchawalit R, and Mongkolsuk S
- Subjects
- Agrobacterium tumefaciens chemistry, Agrobacterium tumefaciens genetics, Amino Acid Motifs, Amino Acid Sequence, Bacterial Proteins genetics, Molecular Sequence Data, Mutation, Transcription Factors genetics, Agrobacterium tumefaciens metabolism, Bacterial Proteins chemistry, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial, Transcription Factors chemistry, Transcription Factors metabolism
- Abstract
The key amino acid residues that influence the function of the Agrobacterium tumefaciens iron response regulator protein (Irr(At) ) were investigated. Several Irr(At) mutant proteins containing substitutions in amino acids corresponding to candidate metal- and haem-binding sites were constructed. The ability of the mutant proteins to repress the promoter of the membrane bound ferritin (mbfA) gene was investigated using a promoter-lacZ fusion assay. A single mutation at residue H94 significantly decreased the repressive activity of Irr(At) . Multiple mutation analysis revealed the importance of H45, H65, the HHH motif (H92, H93 and H94) and H127 for the repressor function of Irr(At) . H94 is essential for the iron responsiveness of Irr(At) . Furthermore, the Irr(At) mutant proteins showed differential abilities to complement the H(2) O(2) -hyper-resistant phenotype of an irr mutant., (© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
4. Agrobacterium tumefaciens membrane-bound ferritin plays a role in protection against hydrogen peroxide toxicity and is negatively regulated by the iron response regulator.
- Author
-
Ruangkiattikul N, Bhubhanil S, Chamsing J, Niamyim P, Sukchawalit R, and Mongkolsuk S
- Subjects
- Agrobacterium tumefaciens growth & development, Agrobacterium tumefaciens metabolism, Ferritins genetics, Gene Knockout Techniques, Genetic Complementation Test, Iron metabolism, Iron toxicity, Membrane Proteins genetics, Agrobacterium tumefaciens drug effects, Bacterial Proteins metabolism, Ferritins metabolism, Gene Expression Regulation, Bacterial, Hydrogen Peroxide metabolism, Hydrogen Peroxide toxicity, Membrane Proteins metabolism, Transcription Factors metabolism
- Abstract
An Agrobacterium tumefaciens membrane-bound ferritin (mbfA) mutant was generated to assess the physiological functions of mbfA in response to iron and hydrogen peroxide (H(2) O(2) ) stresses. Wild-type and the mbfA mutant strains showed similar growth under high- and low-iron conditions. The mbfA mutant was more sensitive to H(2) O(2) than wild-type strain. Expression of a functional mbfA gene could complement the H(2) O(2) -hypersensitive phenotype of the mbfA mutant and a rhizobial iron regulator (rirA) mutant, suggesting that MbfA protects cells from H(2) O(2) toxicity by sequestering intracellular free iron, thus preventing the Fenton reaction. The expression of mbfA could be induced in response to iron and to H(2) O(2) treatment. The iron response regulator (irr) also acted as a repressor of mbfA expression. An irr mutant had high constitutive expression of mbfA, which partly contributed to the H(2) O(2) -hyperresistant phenotype of the irr mutant. The data reported here demonstrate an important role of A. tumefaciens MbfA in the cellular defence against iron and H(2) O(2) stresses., (© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
5. McsA and the roles of metal-binding motif in Staphylococcus aureus.
- Author
-
Sitthisak S, Kitti T, Boonyonying K, Wozniak D, Mongkolsuk S, and Jayaswal RK
- Subjects
- Amino Acid Motifs, Bacterial Proteins genetics, Binding Sites, Cadmium metabolism, Copper metabolism, Gene Expression Regulation, Bacterial, Molecular Sequence Data, Protein Binding, Staphylococcus aureus chemistry, Staphylococcus aureus genetics, Bacterial Proteins chemistry, Bacterial Proteins metabolism, Metals, Heavy metabolism, Staphylococcus aureus metabolism
- Abstract
McsA is a key modulator of stress response in Staphylococcus aureus that contains four CXXC potential metal-binding motifs at the N-terminal. Staphylococcus aureus ctsR operon encodes ctsR, clpC, and putative mcsA and mcsB genes. The expression of the ctsR operon in S. aureus was shown to be induced in response to various types of heavy metals such as copper and cadmium. McsA was cloned and overexpressed, and purified product was tested for metal-binding activity. The protein bound to Cu(II), Zn(II), Co(II), and Cd(II). No binding with any heavy metal except copper was found when we performed site-directed mutagenesis of Cys residues of three CXXC motifs of McsA. These data suggest that two conserved cysteine ligands provided by one CXXC motif are required to bind copper ions. In addition, using a bacterial two-hybrid system, McsA was found to be able to bind to McsB and CtsR of S. aureus and the CXXC motif was needed for the binding. This indicates that the Cys residues in the CXXC motif are involved in metal binding and protein interaction., (© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
6. Genes for hydrogen peroxide detoxification and adaptation contribute to protection against heat shock in Xanthomonas campestris pv. campestris.
- Author
-
Buranajitpakorn S, Piwkam A, Charoenlap N, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Biotransformation, Hydrogen Peroxide metabolism, Hydrogen Peroxide toxicity, Oxidants metabolism, Oxidants toxicity, Xanthomonas campestris drug effects, Xanthomonas campestris radiation effects, Hot Temperature, Microbial Viability drug effects, Microbial Viability radiation effects, Oxidative Stress, Stress, Physiological, Xanthomonas campestris enzymology, Xanthomonas campestris physiology
- Abstract
Xanthomonas campestris pv. campestris, a soil-borne plant-pathogenic bacterium, is exposed to multiple stresses in the environment and during interaction with a host plant. The roles of hydrogen peroxide (H(2) O(2) )-protective genes (katA, katG, and ahpC) and a peroxide sensor/transcription regulator (oxyR) in the viability of X. campestris pv. campestris at an elevated temperature were evaluated. The single katA and katG mutants showed moderate decreased survival after the heat treatment, while the double katA-katG and oxyR mutants were the most vulnerable to the heat treatment compared with a wild-type strain. However, ahpC provided no protective function against the heat treatment. Flow cytometric analysis revealed an increased accumulation of peroxide in cells treated with heat. Altogether, the data revealed a crucial role of genes in the H(2) O(2) detoxification system for protection against lethal heat shock in X. campestris pv. campestris., (© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
7. Copper ions potentiate organic hydroperoxide and hydrogen peroxide toxicity through different mechanisms in Xanthomonas campestris pv. campestris.
- Author
-
Patikarnmonthon N, Nawapan S, Buranajitpakorn S, Charoenlap N, Mongkolsuk S, and Vattanaviboon P
- Subjects
- Bacterial Proteins genetics, Drug Resistance, Bacterial genetics, Xanthomonas campestris genetics, Copper pharmacology, Hydrogen Peroxide toxicity, Ions pharmacology, Xanthomonas campestris drug effects, Xanthomonas campestris metabolism
- Abstract
Copper (Cu)-based biocides are important chemical controls for both fungal and bacterial diseases in crop fields. Here, we showed that Cu ions at a concentration of 100 μM enhanced t-butyl hydroperoxide (tBOOH) and hydrogen peroxide (H(2) O(2) ) killing of Xanthomonas campestris pv. campestris through different mechanisms. The addition of an antilipid peroxidation agent (α-tocopherol) and hydroxyl radical scavengers (glycerol and dimethyl sulphoxide) partially protected the bacteria from the Cu-enhanced tBOOH and H(2) O(2) killing, respectively. Inactivation of the alkyl hydroperoxide reductase gene rendered the mutant vulnerable to lethal doses of copper sulphate, which could be alleviated by the addition of an H(2) O(2) scavenger (pyruvate) and α-tocopherol. Taken together, the data suggest that Cu ions influence the killing effect of tBOOH through the stimulation of lipid peroxidation, while hydroxyl radical production is the underlying mechanism responsible for the Cu-ion-enhanced H(2) O(2) killing effects., (© 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
8. Mini-Tn7 vectors as genetic tools for gene cloning at a single copy number in an industrially important and phytopathogenic bacteria, Xanthomonas spp.
- Author
-
Jittawuttipoka T, Buranajitpakorn S, Fuangthong M, Schweizer HP, Vattanaviboon P, and Mongkolsuk S
- Subjects
- DNA, Bacterial chemistry, DNA, Bacterial genetics, Molecular Sequence Data, Sequence Analysis, DNA, DNA Transposable Elements, Genetic Engineering methods, Genetic Vectors, Molecular Biology methods, Mutagenesis, Insertional methods, Xanthomonas campestris genetics
- Abstract
Transposon mini-Tn7 vectors insert into the chromosome of several Gram-negative bacteria in a site-specific manner. Here, we showed the application of mini-Tn7 as single copy site-specific integration vector system for Xanthomonas campestris pv. campestris. The transposition of the mini-Tn7 into the bacterial genome was detected at a Tn7 attachment (attTn7) site located downstream of glmS1. Furthermore, using a newly constructed vector pBBR1FLP2 containing the flipase (FLP) recombinase for site-specific excision of the sequence between the FLP recombinase target (FRT) sites, and a sacB counter selection marker, an unmarked mini-Tn7 insertion mutant was created. Mini-Tn7 insertion did not affect bacterial virulence on the tested plant. The mini-Tn7 and FLP-FRT systems also work well in Xanthomonas oryzae pv. oryzae.
- Published
- 2009
- Full Text
- View/download PDF
9. Inactivation of thioredoxin-like gene alters oxidative stress resistance and reduces cytochrome c oxidase activity in Agrobacterium tumefaciens.
- Author
-
Tanboon W, Chuchue T, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Agrobacterium tumefaciens genetics, Anti-Bacterial Agents pharmacology, Bacterial Proteins genetics, Catalase metabolism, Gene Knockout Techniques, Hydrogen Peroxide pharmacology, Oxidative Stress, Superoxide Dismutase metabolism, Superoxides pharmacology, Thioredoxins genetics, Agrobacterium tumefaciens physiology, Bacterial Proteins physiology, Electron Transport Complex IV metabolism, Stress, Physiological, Thioredoxins physiology
- Abstract
Thioredoxin-like protein (TlpA) is a membrane-anchored periplasmic protein that contains a thioredoxin domain at its C-terminus. An Agrobacterium tumefaciens mutant lacking functional tlpA shows increased sensitivity to a superoxide generator, increased resistance to H2O2, and reduced cytochrome c oxidase activity. Whereas the levels of antioxidant enzymes, including total superoxide dismutase (SOD) and catalases, are unaltered, high expression of periplasmic SOD partially restores the superoxide hypersensitivity of the mutant, suggesting an accumulation of superoxide anions in the periplasm. The change in the ability of the mutant to cope with H2O2 stress is independent of OxyR, an H2O2 sensor and transcription regulator. The presented data indicate that TlpA not only is involved in the proper assembly of cytochrome c but is also implicated in the bacterial oxidative stress response.
- Published
- 2009
- Full Text
- View/download PDF
10. Mutation in sco affects cytochrome c assembly and alters oxidative stress resistance in Agrobacterium tumefaciens.
- Author
-
Saenkham P, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Amino Acid Motifs, Copper metabolism, Membrane Proteins chemistry, Membrane Proteins genetics, Membrane Proteins metabolism, Mitochondria metabolism, Mitochondrial Proteins chemistry, Mitochondrial Proteins metabolism, Mutagenesis, Site-Directed, Agrobacterium tumefaciens enzymology, Agrobacterium tumefaciens genetics, Agrobacterium tumefaciens metabolism, Agrobacterium tumefaciens physiology, Electron Transport Complex IV metabolism, Heat-Shock Response, Mitochondrial Proteins genetics, Mutation, Oxidative Stress
- Abstract
Sco (for the synthesis of cytochrome c oxidase) is a mitochondrial membrane protein essential for the correct assembly of cytochrome c oxidase. sco homolog genes exist in a wide variety of bacterial species. Inactivation of Agrobacterium tumefaciens sco leads to markedly decreased cytochrome c oxidase activity. This phenotype can be complemented by either supplementing the culture medium with copper or by a plasmid containing sco. The sco mutant also alters resistance to a superoxide generator menadione and H2O2. Mutational analysis of conserved cysteine residues and a histidine residue within the putative copper ions binding motif of Sco indicates that these residues are essential for the biological activity of Sco. To summarize, we find that A. tumefaciens sco is required for the delivery of copper into active cytochrome c oxidase and in maintaining optimal resistance levels to oxidative stress.
- Published
- 2009
- Full Text
- View/download PDF
11. Agrobacterium tumefaciens iron superoxide dismutases have protective roles against singlet oxygen toxicity generated from illuminated Rose Bengal.
- Author
-
Saenkham P, Utamapongchai S, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Agrobacterium tumefaciens drug effects, Agrobacterium tumefaciens growth & development, Culture Media, Isoenzymes genetics, Isoenzymes metabolism, Mutation, Singlet Oxygen metabolism, Superoxide Dismutase genetics, Agrobacterium tumefaciens enzymology, Gene Expression Regulation, Bacterial, Light, Rose Bengal metabolism, Singlet Oxygen toxicity, Superoxide Dismutase metabolism
- 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.
- Published
- 2008
- Full Text
- View/download PDF
12. Challenging Xanthomonas campestris with low levels of arsenic mediates cross-protection against oxidant killing.
- Author
-
Hrimpeng K, Prapagdee B, Banjerdkij P, Vattanaviboon P, Dubbs JM, and Mongkolsuk S
- Subjects
- Arsenites metabolism, Bacterial Proteins biosynthesis, Blotting, Northern, Catalase biosynthesis, Colony Count, Microbial, Gene Deletion, Gene Expression Regulation, Bacterial, Genes, Regulator, Hydrogen Peroxide pharmacology, Peroxidases biosynthesis, Peroxiredoxins, Sodium Compounds metabolism, Xanthomonas campestris genetics, Adaptation, Physiological, Anti-Bacterial Agents pharmacology, Arsenites pharmacology, Oxidants pharmacology, Sodium Compounds pharmacology, Xanthomonas campestris drug effects, Xanthomonas campestris physiology
- Abstract
Xanthomonas encounters highly toxic reactive oxygen species (ROS) from many sources, such as those generated by plants against invading bacteria, other soil bacteria and from aerobic respiration. Thus, conditions that alter intracellular ROS levels such as exposure to toxic metalloids would have profound effects on bacterial physiology. Here, we report that exposure of Xanthomonas campestris pv. phaseoli (Xp) to low levels of arsenic induces physiological cross-protection against killing by H(2)O(2) and organic hydroperoxide but not a superoxide generator. Cross-protection against H(2)O(2) and organic hydroperoxide toxicity was due to increased expression of genes encoding major peroxide-metabolizing enzymes such as alkyl hydroperoxide reductase (AhpC), catalase (KatA) and organic hydroperoxide resistance protein (Ohr). Arsenic-induced protection against H(2)O(2) and organic hydroperoxide requires the peroxide stress response regulators, OxyR and OhrR, respectively. Moreover, analyses of double mutants of the major H(2)O(2) and organic hyproperoxide-scavenging enzymes, Xp ahpC katA and Xp ahpC ohr, respectively, suggested the existence of unidentified OxyR- and OhrR-regulated genes that are involved in arsenic-induced resistance to H(2)O(2) and organic hyproperoxide killing in Xp. These arsenic-induced physiological alterations could play an important role in bacterial survival both in the soil environment and during plant-pathogen interactions.
- Published
- 2006
- Full Text
- View/download PDF
13. Analysis of mutations that alter HO sensing and transcription regulation properties of a global peroxide regulator OxyR in Xanthomonas campestris pv. phaseoli.
- Author
-
Whangsuk W and Mongkolsuk S
- Subjects
- Bacterial Proteins genetics, Drug Resistance, Bacterial, Hydrogen Peroxide pharmacology, Mutation, Oxidation-Reduction, Promoter Regions, Genetic, Transcription Factors genetics, Transcription, Genetic, Xanthomonas campestris drug effects, Bacterial Proteins physiology, Peroxides metabolism, Transcription Factors physiology, Xanthomonas campestris metabolism
- Abstract
OxyR5, from a Xanthomonas campestris pv. phaseoli H(2)O(2)-resistant mutant, contains the two mutations G197D and L301R. The protein exists in its oxidized-like form in the absence of oxidants as judged by the protein's ability to activate the ahpC promoter. Analysis of DNase I footprint patterns indicates that under reducing conditions OxyR5 and OxyRG197D bind to the target site in the ahpC promoter in a manner similar to oxidized wild-type OxyR. Site-directed mutagenesis showed that OxyR5 behaves like oxidized OxyR, independent of the highly conserved C residues at positions 199 and 208 where, in normal OxyR, a disulfide bond between these residues converts the protein from its reduced to the oxidized form. The presence of aspartic acid or valine residue at position 197 caused OxyR to behave like the oxidized form in uninduced cells. Changing D197 to A or T in OxyR5 resulted in proteins with similar properties to native OxyR. In vivo, OxyR5 probably locked in an oxidized-like conformation, resulting in continuous high-level activation of target genes in the OxyR regulon.
- Published
- 2006
- Full Text
- View/download PDF
14. OxyR mediated compensatory expression between ahpC and katA and the significance of ahpC in protection from hydrogen peroxide in Xanthomonas campestris.
- Author
-
Charoenlap N, Eiamphungporn W, Chauvatcharin N, Utamapongchai S, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Catalase genetics, DNA-Binding Proteins genetics, Heat-Shock Response, Oxidative Stress, Peroxidases genetics, Peroxiredoxins, Repressor Proteins genetics, Transcription Factors genetics, Xanthomonas campestris enzymology, Xanthomonas campestris genetics, Catalase metabolism, DNA-Binding Proteins metabolism, Gene Expression Regulation, Bacterial, Hydrogen Peroxide pharmacology, Peroxidases metabolism, Repressor Proteins metabolism, Transcription Factors metabolism, Xanthomonas campestris physiology
- Abstract
katA and ahpC, encoding monofunctional catalase and alkyl hydroperoxide reductase, respectively, play important protective roles against peroxide toxicity in Xanthomonas campestris pv. phaseoli (Xp). The expression of both katA and ahpC is controlled by the global peroxide sensor and transcriptional activator, OxyR. In Xp, these two genes have compensatory expression patterns. Inactivation of katA leads to an increase in the level of AhpC and a concomitant increase in resistance to tert-butyl hydroperoxide (tBOOH). High-level expression of katA from an expression vector in Xp also lowered the level of ahpC expression. The compensatory regulation of katA and ahpC was mediated by OxyR, since the compensatory response was not observed in an oxyR mutant background. ahpC and katA play important but unequal roles in protecting Xp from H(2)O(2) toxicity. These observations, taken together with a previous observation that an ahpC mutant expresses high levels of KatA and is hyper-resistant to H(2)O(2), suggest the possibility that inactivation of either gene leads to accumulation of intracellular H(2)O(2). This in turn oxidizes reduced OxyR and converts the regulator to the oxidized form that then activates expression of genes in the OxyR regulon.
- Published
- 2005
- Full Text
- View/download PDF
15. The role of a bifunctional catalase-peroxidase KatA in protection of Agrobacterium tumefaciens from menadione toxicity.
- Author
-
Prapagdee B, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Agrobacterium tumefaciens genetics, Gene Expression Regulation, Bacterial, Gene Expression Regulation, Enzymologic, Hydrogen Peroxide metabolism, Mutagenesis, Oxidation-Reduction, Phenotype, Superoxides metabolism, Agrobacterium tumefaciens drug effects, Agrobacterium tumefaciens enzymology, Bacterial Proteins genetics, Bacterial Proteins metabolism, Peroxidases genetics, Peroxidases metabolism, Vitamin K 3 toxicity
- Abstract
Agrobacterium tumefaciens is an aerobic plant pathogenic bacterium that is exposed to reactive oxygen species produced either as by-products of aerobic metabolism or by the defense systems of host plants. The physiological function of the bifunctional catalase-peroxidase (KatA) in the protection of A. tumefaciens from reactive oxygen species other than H(2)O(2) was evaluated in the katA mutant (PB102). Unexpectedly, PB102 was highly sensitive to the superoxide generator menadione. The expression of katA from a plasmid vector complemented the menadione-hypersensitive phenotype. A. tumefaciens possesses an additional catalase gene, a monofunctional catalase encoded by catE. Neither inactivation nor high-level expression of the catE gene altered the menadione resistance level. Moreover, heterologous expression of the catalase-peroxidase-encoding gene katG from Burkholderia pseudomallei, but not the monofunctional catalase gene katE from Xanthomonas campestris could restore normal levels of menadione resistance to PB102. A recent observation suggests that the menadione resistance phenotype involves increased activities of organic peroxide-metabolizing enzymes. Heterologous expression of X. campestris alkyl hydroperoxide reductase from a plasmid vector failed to complement the menadione-sensitive phenotype of PB102. The level of menadione resistance shows a direct correlation with the level of peroxidase activity of KatA. This is a novel role for KatA and suggests that resistance to menadione toxicity is mediated by a new, and as yet unknown, mechanism in A. tumefaciens.
- Published
- 2004
- Full Text
- View/download PDF
16. Oxidant-inducible resistance to hydrogen peroxide killing in Agrobacterium tumefaciens requires the global peroxide sensor-regulator OxyR and KatA.
- Author
-
Eiamphungporn W, Nakjarung K, Prapagdee B, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Adaptation, Physiological, Agrobacterium tumefaciens genetics, Bacterial Proteins genetics, Bacterial Proteins metabolism, Base Sequence, Catalase genetics, Catalase metabolism, DNA, Bacterial genetics, Drug Resistance, Bacterial, Genes, Bacterial, Hydrogen Peroxide metabolism, Mutation, Oxidants pharmacology, Oxidative Stress, Superoxides metabolism, Superoxides pharmacology, Transcription Factors genetics, Transcription Factors metabolism, Vitamin K 3 pharmacology, Agrobacterium tumefaciens drug effects, Agrobacterium tumefaciens metabolism, Hydrogen Peroxide pharmacology
- Abstract
Induced adaptive and cross-protective responses to peroxide stress are important strategies used by bacteria to survive stressful environments. We have shown that exposure to low levels of peroxide (adaptive) and superoxide anions (cross-protection) induced high levels of resistance to peroxide killing in Agrobacterium tumefaciens. The mechanisms and genes involved in these processes have not been identified. Here, the roles played by peroxide (oxyR) and superoxide (soxR) global regulators and a catalase gene (katA) during these responses were investigated. H2O2-induced adaptive protection was completely abolished in both the oxyR and katA mutants. Superoxide generator (menadione)-induced cross-protection to H2O2 killing was observed in a soxR mutant, but not in either an oxyR or a katA mutant. In vivo analysis of the katA promoter, using a katA::lacZ transcriptional fusion, revealed that it could be induced by menadione in an oxyR-dependent manner. These results lead us to conclude that H2O2 and superoxide anions directly or indirectly oxidize OxyR and it is the resulting activation of katA expression that is responsible for the induced protection against lethal concentrations of H2O2.
- Published
- 2003
- Full Text
- View/download PDF
17. Induction of peroxide and superoxide protective enzymes and physiological cross-protection against peroxide killing by a superoxide generator in Vibrio harveyi.
- Author
-
Vattanaviboon P, Panmanee W, and Mongkolsuk S
- Subjects
- Amino Acid Sequence, Bacterial Proteins genetics, Bacterial Proteins metabolism, Base Sequence, Catalase genetics, Catalase metabolism, Glucosephosphate Dehydrogenase genetics, Glucosephosphate Dehydrogenase metabolism, Molecular Sequence Data, Peroxidases genetics, Peroxidases metabolism, Peroxides metabolism, Peroxides pharmacology, Peroxiredoxins, Superoxide Dismutase genetics, Superoxide Dismutase metabolism, Superoxides metabolism, Superoxides pharmacology, Transcription Factors genetics, Transcription Factors metabolism, Vibrio growth & development, Vibrio physiology, Vitamin K 3 pharmacology, Gene Expression Regulation, Bacterial, Heat-Shock Response, Oxidative Stress, Vibrio drug effects, Vibrio enzymology
- Abstract
Vibrio harveyi is a causative agent of destructive luminous vibriosis in farmed black tiger prawn (Penaeus monodon). V. harveyi peroxide and superoxide stress responses toward elevated levels of a superoxide generated by menadione were investigated. Exposure of V. harveyi to sub-lethal concentrations of menadione induced high expression of genes in both the OxyR regulon (e.g., a monofunctional catalase or KatA and an alkyl hydroperoxide reductase subunit C or AhpC), and the SoxRS regulon (e.g., a superoxide dismutase (SOD) and a glucose-6-phosphate dehydrogenase). V. harveyi expressed two detectable, differentially regulated SOD isozymes, [Mn]-SOD and [Fe]-SOD. [Fe]-SOD was expressed constitutively throughout the growth phase while [Mn]-SOD was expressed at the stationary phase and could be induced by a superoxide generator. Physiologically, pre-treatment of V. harveyi with menadione induced cross-protection against subsequent exposure to killing concentrations of H(2)O(2). This induced cross-protection required newly synthesized proteins. However, the treatment did not induce significant protection against exposures to killing concentrations of menadione itself or cross-protect against an organic hydroperoxide (tert-butyl hydroperoxide). Unexpectedly, growing V. harveyi in high-salinity media induced protection against menadione killing. This protection was independent of SOD induction. Stationary-phase cells were more resistant to menadione killing than exponential-phase cells. The induction of oxidative stress protective enzymes and stress-altered physiological responses could play a role in the survival of this bacterium in the host marine crustaceans.
- Published
- 2003
- Full Text
- View/download PDF
18. Characterization of Xanthomonas oryzae pv. oryzae recX, a gene that is required for high-level expression of recA.
- Author
-
Sukchawalit R, Vattanaviboon P, Utamapongchai S, Vaughn G, and Mongkolsuk S
- Subjects
- Blotting, Western, Mutation, Physical Chromosome Mapping, Plasmids genetics, Polymerase Chain Reaction, Transcription, Genetic, Xanthomonas metabolism, Xanthomonas physiology, Bacterial Proteins genetics, Bacterial Proteins metabolism, DNA-Binding Proteins, Gene Expression Regulation, Bacterial, Rec A Recombinases genetics, Rec A Recombinases metabolism, Xanthomonas genetics
- Abstract
Analysis of the nucleotide sequence downstream from the Xanthomonas oryzae pv. oryzae recA gene reveals two orfs designated orfX and recX. The former has the potential to code for a 5.6 kDa protein of unknown function while the latter encodes for a putative 14.6 kDa protein with homology to RecX from various bacteria. Northern blot analysis and RT-PCR results show that recA-orfX-recX are co-regulated and arranged in an operon. A recX mutant was constructed. The mutant has no obvious growth defects or stress response defects, except that it cannot support high-level expression of recA from an expression vector. Introduction of the plasmid containing recA into the recX mutant resulted in reduced transformation efficiency and all transformants tested had mutations with reduced RecA levels. Moreover, the recX mutant has reduced basal levels of RecA. This has not been observed in other bacteria. When inactivated recX was complemented in trans, both changes were reversed. recX mutation has no effect on the regulation of the recA promoter, suggesting that its effect on the RecA level could be post-transcriptional.
- Published
- 2001
- Full Text
- View/download PDF
19. Unusual adaptive, cross protection responses and growth phase resistance against peroxide killing in a bacterial shrimp pathogen, Vibrio harveyi.
- Author
-
Vattanaviboon P and Mongkolsuk S
- Subjects
- Animals, Catalase biosynthesis, Drug Resistance, Enzyme Induction, Oxidants toxicity, Oxidative Stress, Peroxidases biosynthesis, Peroxiredoxins, Vibrio Infections veterinary, Adaptation, Biological, Bacterial Proteins, Decapoda microbiology, Hydrogen Peroxide toxicity, Vibrio drug effects
- Abstract
Oxidant induced protection against peroxide killing was investigated in a prawn bacterial pathogen, Vibrio harveyi. Exposure to 250 microM H(2)O(2) induced adaptive protection against subsequent exposure to killing concentrations of H(2)O(2). In addition, 200 microM t-butyl hydroperoxide (tBOOH) induced cross protection to H(2)O(2) killing. On the other hand, peroxide pretreatment did not induce protection against tBOOH killing. Peroxide induced adaptive and cross protection responses required new protein synthesis and were abolished by addition of a protein synthesis inhibitor. Pretreatments of V. harveyi with 250 microM H(2)O(2) and 200 microM tBOOH induced an increase in peroxide scavenging enzymes, catalase and alkyl hydroperoxide reductase subunit C. In addition, stationary phase cells of V. harveyi were more resistant to H(2)O(2) and iodoacetamide killing but highly susceptible to tBOOH killing compared to exponential phase cells. Many aspects of the oxidative stress response of V. harveyi are different from those of other bacteria and these factors may be important for bacterial survival in the environment and during interactions with host shrimp.
- Published
- 2001
- Full Text
- View/download PDF
20. Xanthomonas oryzae pv. oryzae recA is transcribed and regulated from multiple promoters.
- Author
-
Sukchawalit R and Mongkolsuk S
- Subjects
- Base Sequence, Blotting, Western, DNA Primers, Gene Deletion, Molecular Sequence Data, Oryza microbiology, Plant Diseases microbiology, Rec A Recombinases metabolism, SOS Response, Genetics genetics, Xanthomonas metabolism, Gene Expression Regulation, Bacterial, Promoter Regions, Genetic, Rec A Recombinases genetics, Transcription, Genetic genetics, Xanthomonas genetics
- Abstract
Transcription regulation of Xanthomonas oryzae pv. oryzae recA was characterized. Primer extension experiments showed that recA is transcribed from three promoters designated P1, P2 and P3. The sequences of -10 and -35 regions of these promoters have moderate homology to the proposed consensus sequence for a Xanthomonas promoter. Putative SOS boxes were identified in the vicinity of P1 and P2 promoters. Deletion analysis and in vivo monitoring of promoter activity of these promoters revealed that the three promoters have different characteristics. P1 and P2 show stress-inducible high and low promoter strengths respectively. P3 is a non-inducible moderate promoter strength. These promoters are regulated by two SOS boxes. The multiplicity of promoters and SOS boxes provides back-up systems to ensure proper regulation of recA.
- Published
- 2001
- Full Text
- View/download PDF
21. Construction and characterization of regulated L-arabinose-inducible broad host range expression vectors in Xanthomonas.
- Author
-
Sukchawalit R, Vattanaviboon P, Sallabhan R, and Mongkolsuk S
- Subjects
- AraC Transcription Factor, Blotting, Western, Chloramphenicol O-Acetyltransferase genetics, Chloramphenicol O-Acetyltransferase metabolism, Dose-Response Relationship, Drug, Drug Resistance, Microbial, Escherichia coli drug effects, Escherichia coli genetics, Escherichia coli metabolism, Escherichia coli Proteins, Gene Transfer Techniques, Genetic Vectors drug effects, Pseudomonas aeruginosa drug effects, Pseudomonas aeruginosa genetics, Pseudomonas aeruginosa metabolism, Repressor Proteins genetics, Tetracycline pharmacology, Time Factors, Xanthomonas drug effects, Xanthomonas enzymology, Arabinose pharmacology, Bacterial Proteins, Genetic Vectors genetics, Transcription Factors, Xanthomonas genetics
- Abstract
Several versions of broad host range (BHR), L-arabinose-inducible expression vectors were constructed. These expression vectors were based on a high copy number BHR pBBR1MCS-4 replicon that could replicate in both enteric and non-enteric Gram-negative bacteria. Two versions of expression cassettes containing multiple cloning sites either with or without a ribosome binding site were placed under transcriptional control of the Escherichia coli BAD promoter and araC gene. Three versions of vectors containing ampicillin or kanamycin or tetracycline resistance genes as selectable markers were constructed. In all six new L-arabinose-inducible BHR expression vectors containing many unique cloning sites, selectable markers were made to facilitate cloning and expression of genes in various Gram-negative bacteria. A Tn9 chloramphenicol acetyl transferase (cat) gene was cloned into an expression vector, resulting in pBBad18Acat that was used to establish optimal expression conditions (addition of 0.02% L-arabinose to mid-exponential phase cells for at least 1 h) in a Xanthomonas campestris pv. phaseoli. Comparison of the Cat enzyme activities between uninduced and a 180-min L-arabinose-induced culture showed a greater than 150-fold increased Cat specific activity. In addition, L-arabinose induction of exponential phase cells harboring pBBad18Acat gave a higher amount of Cat than similarly treated stationary phase cells. The usefulness of the expression vector was also demonstrated in both enteric and non-enteric Gram-negative bacteria.
- Published
- 1999
- Full Text
- View/download PDF
22. Construction and physiological analysis of a Xanthomonas oryzae pv. oryzae recA mutant.
- Author
-
Mongkolsuk S, Rabibhadana S, Sukchavalit R, and Vaughn G
- Subjects
- Blotting, Southern, Blotting, Western, Hydrogen Peroxide pharmacology, Polymerase Chain Reaction, Time Factors, Xanthomonas drug effects, Xanthomonas physiology, Mutagenesis, Insertional, Rec A Recombinases genetics, Xanthomonas genetics
- Abstract
A Xoo recA insertion inactivation mutant was constructed. The mutant, lacking RecA, showed increased sensitivity towards mutagen killing. This phenotype could be complemented by a cloned, functional recA. Unlike other bacteria, both the recA mutant and the parental strain had similar level of resistance to H2O2 killing and peroxide-induced mutagenesis.
- Published
- 1998
- Full Text
- View/download PDF
23. Characterization and expression analysis of a Xanthomonas oryzae pv. oryzae recA.
- Author
-
Rabibhadana S, Chamnongpol S, Sukchawalit R, Ambulos NP Jr, Trempy JE, and Mongkolsuk S
- Subjects
- Bacterial Proteins genetics, Blotting, Northern, DNA Damage, Mutagens pharmacology, Oxidative Stress genetics, Promoter Regions, Genetic, RNA, Messenger analysis, Rec A Recombinases analysis, Sequence Analysis, DNA, Ultraviolet Rays, Xanthomonas drug effects, Xanthomonas growth & development, Gene Expression Regulation, Bacterial drug effects, Gene Expression Regulation, Bacterial radiation effects, Rec A Recombinases genetics, Xanthomonas genetics
- Abstract
Nucleotide sequence of Xanthomonas oryzae pv. oryzae (Xoo) DNA from pSM-A1 was determined and sequence analysis revealed an ORF with high homology to RecA proteins. Expression analysis using an anti-RecA antibody demonstrates that MMS treatment induces recA in Xanthomonas strains but not in an Escherichia coli harbouring cloned Xoo recA. This indicates the existence of a recA regulatory mechanism in Xanthomonas that is not function in E. coli. In Xoo, recA was highly induced by treatments with chemical mutagens, UV and peroxides, while superoxides, a thiol agent, a heavy metal and heat shock were not inducers. The increased amount of RecA induced by H2O2 or MMS treatments were due to increased transcription of recA. recA showed no growth phase or starvation regulation. The pattern of recA regulation in Xoo could play important roles in stress survival in the environment and during plant-microbe interactions.
- Published
- 1998
- Full Text
- View/download PDF
24. Isolation and characterization of a multiple peroxide resistant mutant from Xanthomonas campestris pv. phaseoli.
- Author
-
Fuangthong M and Mongkolsuk S
- Subjects
- Bacterial Proteins analysis, Hydrogen Peroxide pharmacology, Mutation, Oxidative Stress, Xanthomonas genetics, Xanthomonas growth & development, tert-Butylhydroperoxide, Peroxides pharmacology, Xanthomonas drug effects
- Abstract
We have isolated a spontaneous multiple peroxide resistant Xanthamonas campestris pv. phaseoli mutant (XpHr). In the presence of peroxides, the mutant had a higher growth rate than the parent. It also had a greater than 100-fold increase in resistance levels to H2O2 killing but only slightly more resistance to tert-butyl hydroperoxide killing. Increases in activity were detected for the peroxide scavenging enzymes catalase (100-fold) and AhpC (over 30-fold). Also observed was cross-resistance to thermal killing; however, no cross-resistance to other oxidants or chemicals was found. Analysis of protein profiles revealed that proteins with molecular masses of 22 and 58 kDa were accumulated while proteins of 29, 33 and 41 kDa were depressed in the mutant. These results indicate that the mutant may have defect(s) in peroxide regulation, which resulted in high constitutive expression of peroxide scavenging enzymes. Nevertheless, the mutant retained growth phase dependent regulation of peroxide killing. The mutant should be useful in unravelling the nature of a complex peroxide stress regulon.
- Published
- 1997
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.