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Lazra Y, Gandu B, Amar ID, Emanuel E, Cahan R. Effects of Atmospheric Plasma Corona Discharge on Agrobacterium tumefaciens Survival. Microorganisms 2021; 10:microorganisms10010032. [PMID: 35056481 PMCID: PMC8780683 DOI: 10.3390/microorganisms10010032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 11/16/2022] Open
Abstract
Soil-borne pathogenic microorganisms are known to cause extensive crop losses. Agrobacterium tumefaciens, a member of the Proteobacteria, causes the neoplastic crown gall disease in plants. Plant protection is mainly based on toxic chemicals that are harmful to the environment. The use of cold atmospheric-pressure plasma is an attractive method for microbial eradication. Its antimicrobial mechanism includes the formation of large quantities of reactive oxygen species (ROS). The advantages of eradicating bacteria using cold plasma are not needed for chemicals, short treatment, and environmental temperatures. This study examined the impact of plasma corona discharge exposure on A. tumefaciens viability, membrane permeability, relative cell size, and ROS formation. The results showed that 90 s of plasma exposure led to a reduction by four orders of magnitude when the initial concentration was 1 × 107 CFU/mL and in a dry environment. When the initial concentration was 1 × 106 CFU/mL, 45 s of exposure resulted in total bacterial eradication. In a liquid environment, in an initial concentration of 2.02 × 106 CFU/mL, there was no complete bacterial eradication even at the most prolonged examined exposure (90 s). The influence of plasma treatment on the membrane permeability of A. tumefaciens, and their possible recovery, were analyzed using flow cytometer analysis using propidium iodide (PI). When the plasma-treated bacteria were suspended in Luria–Bertani (LB) (rich medium), the PI-positive count of the plasma-treated bacteria after two hours was 12 ± 3.9%. At the 24th hour, this percentage was only 1.74 ± 0.6%, as the control (0.7 ± 0.1%). These results may indicate the repair of the plasma-treated bacteria that were suspended in LB. At the 24th hour, the relative cell size of the treated bacteria shifted to the right, to ~3 × 104 forward side scatter (FSC), about 0.5-fold higher than the untreated cells. Measurement of the ROS showed that the intracellular fluorescence of the 90-s plasma-treated cells led to significant fluorescence formation of 32 relative fluorescence units (RFU)/cell (9 × 104 fold, compared to the nontreated cells). This study showed that cold plasma is a useful method for A. tumefaciens eradication. The eradication mechanism involves ROS generation, membrane permeability, and changes in cell size.
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Affiliation(s)
- Yulia Lazra
- Department of Chemical Engineering and Biotechnology, Ariel University, Ariel 40700, Israel; (Y.L.); (B.G.); (I.D.A.); (E.E.)
| | - Bharath Gandu
- Department of Chemical Engineering and Biotechnology, Ariel University, Ariel 40700, Israel; (Y.L.); (B.G.); (I.D.A.); (E.E.)
- Department of Environmental Studies, University of Delhi, New Delhi 110007, India
| | - Irina Dubrovin Amar
- Department of Chemical Engineering and Biotechnology, Ariel University, Ariel 40700, Israel; (Y.L.); (B.G.); (I.D.A.); (E.E.)
| | - Efrat Emanuel
- Department of Chemical Engineering and Biotechnology, Ariel University, Ariel 40700, Israel; (Y.L.); (B.G.); (I.D.A.); (E.E.)
| | - Rivka Cahan
- Department of Chemical Engineering and Biotechnology, Ariel University, Ariel 40700, Israel; (Y.L.); (B.G.); (I.D.A.); (E.E.)
- Correspondence: ; Tel.: +972-54-774-0293
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Zeng Z, He X, Li F, Zhang Y, Huang Z, Wang Y, Li K, Bao Y, Iqbal M, Fakhar-E-Alam Kulyar M, Li J. Probiotic Properties of Bacillus proteolyticus Isolated From Tibetan Yaks, China. Front Microbiol 2021; 12:649207. [PMID: 34484132 PMCID: PMC8416245 DOI: 10.3389/fmicb.2021.649207] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 07/20/2021] [Indexed: 12/17/2022] Open
Abstract
Yaks (Bos grunniens) live primarily in high-altitude hypoxic conditions and have a unique intestinal micro-ecosystem, remarkable adaptability, and strong climatic resistance. Accumulating evidence revealed the importance of probiotics in host metabolism, gut microbiota, growth performance, and health. The goal of this study was to screen out probiotics with excellent probiotic potential for clinical application. In this study, four strains of Bacillus, i.e., Bacillus proteolyticus (named Z1 and Z2), Bacillus amyloliquefaciens (named J), and Bacillus subtilis (named K), were isolated and identified. Afterward, their probiotic potential was evaluated. Antioxidant activity tests revealed that Z1 had the highest DPPH and hydroxyl radical scavenging activity, whereas Z2 had higher reducing power and inhibited lipid peroxidation. Additionally, the antibacterial testing revealed that all strains were antagonistic to three indicator pathogens, Escherichia coli C83902, Staphylococcus aureus BNCC186335, and Salmonella enteritidis NTNC13349. These isolates also had a higher hydrophobicity, autoaggregation, and acid and bile tolerance, all of which helped to survive and keep dangerous bacteria out of the host intestine. Importantly, all strains could be considered safe in terms of antibiotic susceptibility and lack of hemolysis. In conclusion, this is the first study to show that B. proteolyticus and B. amyloliquefaciens isolated from yaks have probiotic potential, providing a better foundation for future clinical use.
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Affiliation(s)
- Zhibo Zeng
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xiaoling He
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Feiran Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yan Zhang
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Zonghao Huang
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yaping Wang
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Kun Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yuhua Bao
- Tibet Autonomous Region Biological Drug Manufacturing Plant, Lhasa, China
| | - Mudassar Iqbal
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Faculty of Veterinary and Animal Sciences, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | | | - Jiakui Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,College of Animals Husbandry and Veterinary Medicine, Tibet Agricultural and Animal Husbandry University, Linzhi, China
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3
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Budnick JA, Sheehan LM, Ginder MJ, Failor KC, Perkowski JM, Pinto JF, Kohl KA, Kang L, Michalak P, Luo L, Heindl JE, Caswell CC. A central role for the transcriptional regulator VtlR in small RNA-mediated gene regulation in Agrobacterium tumefaciens. Sci Rep 2020; 10:14968. [PMID: 32917931 PMCID: PMC7486931 DOI: 10.1038/s41598-020-72117-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 07/17/2020] [Indexed: 12/28/2022] Open
Abstract
LysR-type transcriptional regulators (LTTRs) are the most common type of transcriptional regulators in prokaryotes and function by altering gene expression in response to environmental stimuli. In the class Alphaproteobacteria, a conserved LTTR named VtlR is critical to the establishment of host-microbe interactions. In the mammalian pathogen Brucella abortus, VtlR is required for full virulence in a mouse model of infection, and VtlR activates the expression of abcR2, which encodes a small regulatory RNA (sRNA). In the plant symbiont Sinorhizobium meliloti, the ortholog of VtlR, named LsrB, is involved in the symbiosis of the bacterium with alfalfa. Agrobacterium tumefaciens is a close relative of both B. abortus and S. meliloti, and this bacterium is the causative agent of crown gall disease in plants. In the present study, we demonstrate that VtlR is involved in the ability of A. tumefaciens to grow appropriately in artificial medium, and an A. tumefaciens vtlR deletion strain is defective in motility, biofilm formation, and tumorigenesis of potato discs. RNA-sequencing analyses revealed that more than 250 genes are dysregulated in the ∆vtlR strain, and importantly, VtlR directly controls the expression of three sRNAs in A. tumefaciens. Taken together, these data support a model in which VtlR indirectly regulates hundreds of genes via manipulation of sRNA pathways in A. tumefaciens, and moreover, while the VtlR/LsrB protein is present and structurally conserved in many members of the Alphaproteobacteria, the VtlR/LsrB regulatory circuitry has diverged in order to accommodate the unique environmental niche of each organism.
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Affiliation(s)
- James A Budnick
- Center for One Health Research, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Lauren M Sheehan
- Center for One Health Research, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Miranda J Ginder
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA
| | - Kevin C Failor
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA
| | - Julia M Perkowski
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA
| | - John F Pinto
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA
| | - Kirsten A Kohl
- Center for One Health Research, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Lin Kang
- Edward via College of Osteopathic Medicine, Blacksburg, VA, 24060, USA
| | - Pawel Michalak
- Center for One Health Research, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
- Edward via College of Osteopathic Medicine, Blacksburg, VA, 24060, USA
- Institute of Evolution, Haifa University, 3498838, Haifa, Israel
| | - Li Luo
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Plant Science Center, Shanghai University, Shanghai, 200444, China
| | - Jason E Heindl
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA.
| | - Clayton C Caswell
- Center for One Health Research, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA.
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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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5
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Succinic Semialdehyde Promotes Prosurvival Capability of Agrobacterium tumefaciens. J Bacteriol 2016; 198:930-40. [PMID: 26755630 DOI: 10.1128/jb.00373-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 12/10/2015] [Indexed: 01/25/2023] Open
Abstract
UNLABELLED Succinic semialdehyde (SSA), an important metabolite of γ-aminobutyric acid (GABA), is a ligand of the repressor AttJ regulating the expression of the attJ-attKLM gene cluster in the plant pathogen Agrobacterium tumefaciens. While the response of A. tumefaciens to GABA and the function of attKLM have been extensively studied, genetic and physiological responses of A. tumefaciens to SSA remain unknown. In combination with microarray and genetic approaches, this study sets out to explore new roles of the SSA-AttJKLM regulatory mechanism during bacterial infection. The results showed that SSA plays a key role in regulation of several bacterial activities, including C4-dicarboxylate utilization, nitrate assimilation, and resistance to oxidative stress. Interestingly, while the SSA relies heavily on the functional AttKLM in mediating nitrate assimilation and oxidative stress resistance, the compound could regulate utilization of C4-dicarboxylates independent of AttJKLM. We further provide evidence that SSA controls C4-dicarboxylate utilization through induction of an SSA importer and that disruption of attKLM attenuates the tumorigenicity of A. tumefaciens. Taken together, these findings indicate that SSA could be a potent plant signal which, together with AttKLM, plays a vital role in promoting the bacterial prosurvival abilities during infection. IMPORTANCE Agrobacterium tumefaciens is a plant pathogen causing crown gall diseases and has been well known as a powerful tool for plant genetic engineering. During the long history of microbe-host interaction, A. tumefaciens has evolved the capabilities of recognition and response to plant-derived chemical metabolites. Succinic semialdehyde (SSA) is one such metabolite. Previous results have demonstrated that SSA functions to activate a quorum-quenching mechanism and thus to decrease the level of quorum-sensing signals, thereby avoiding the elicitation of a plant defense. Here, we studied the effect of SSA on gene expression at a genome-wide level and reported that SSA also promotes bacterial survival during infection. These findings provide a new insight on the biological significance of chemical signaling between agrobacteria and plant hosts.
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Antiparallel and interlinked control of cellular iron levels by the Irr and RirA regulators of Agrobacterium tumefaciens. J Bacteriol 2011; 193:3461-72. [PMID: 21602352 DOI: 10.1128/jb.00317-11] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The plant pathogen Agrobacterium tumefaciens encodes predicted iron-responsive regulators, Irr and RirA, that function in several other bacteria to control the response to environmental iron levels. Deletion mutations of irr and rirA, alone and in combination, were evaluated for their impact on cellular iron response. Growth was severely diminished in the Δirr mutant under iron-limiting conditions, but reversed to wild-type levels in an Δirr ΔrirA mutant. The level of uncomplexed iron in the Δirr mutant was decreased, whereas the ΔrirA mutant exhibited elevated iron levels. Sensitivity of the Δirr and ΔrirA mutants to iron-activated antimicrobial compounds generally reflected their uncomplexed-iron levels. Expression of genes that encode iron uptake systems was decreased in the Δirr mutant, whereas that of iron utilization genes was increased. Irr function required a trihistidine repeat likely to mediate interactions with heme. Iron uptake genes were derepressed in the ΔrirA mutant. In the Δirr ΔrirA mutant, iron uptake and utilization genes were derepressed, roughly combining the phenotypes of the single mutants. Siderophore production was elevated in the rirA mutant, but most strongly regulated by an RirA-controlled sigma factor. Expression of rirA itself was regulated by Irr, RirA, and iron availability, in contrast to irr expression, which was relatively stable in the different mutants. These studies suggest that in A. tumefaciens, the Irr protein is most active under low-iron conditions, inhibiting iron utilization and activating iron acquisition, while the RirA protein is active under high-iron conditions, repressing iron uptake.
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Montesano Gesualdi N, Chirico G, Catanese MT, Pirozzi G, Esposito F. AROS-29 is involved in adaptive response to oxidative stress. Free Radic Res 2009; 40:467-76. [PMID: 16551573 DOI: 10.1080/10715760600570547] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Transient adaptation to mild oxidative stress was induced in human osteosarcoma cells chronically grown in sub-toxic concentrations of diethylmaleate (DEM), a glutathione (GSH) depleting agent. The adapted cells, compared to untreated cells, contain increased concentrations of GSH (4-6 fold) which, upon DEM withdrawal from the culture medium, return to normal values and are more resistant to subsequent oxidizing stress induced either by toxic concentrations of the same agent or by (H(2)O(2)) treatment. To investigate the molecular mechanisms involved in the adaptive response to oxidative stress, we analyzed the gene expression profiles of DEM-adapted cells by differential display. The expression of adaptive response to oxidative stress (AROS)-29 gene, coding for a transmembrane protein of unknown function, as well as of some known genes involved in energy metabolism, protein folding and membrane traffic is up-regulated in adapted cells. The increased resistance to both DNA damage and apoptosis, in cells stably overexpressing AROS-29, demonstrated its functional role in the protection against oxidative stress.
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Saenkham P, Eiamphungporn W, Farrand SK, Vattanaviboon P, Mongkolsuk S. Multiple superoxide dismutases in Agrobacterium tumefaciens: functional analysis, gene regulation, and influence on tumorigenesis. J Bacteriol 2007; 189:8807-17. [PMID: 17921294 PMCID: PMC2168619 DOI: 10.1128/jb.00960-07] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Accepted: 09/25/2007] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens possesses three iron-containing superoxide dismutases (FeSods) encoded by distinct genes with differential expression patterns. SodBI and SodBII are cytoplasmic isozymes, while SodBIII is a periplasmic isozyme. sodBI is expressed at a high levels throughout all growth phases. sodBII expression is highly induced upon exposure to superoxide anions in a SoxR-dependent manner. sodBIII is expressed only during stationary phase. Analysis of the physiological function of sods reveals that the inactivation of sodBI markedly reduced levels of resistance to a superoxide generator, menadione. A mutant lacking all three Sod enzymes is the most sensitive to menadione treatment, indicating that all sods contribute at various levels towards the overall menadione resistance level. Sods also have important roles in A. tumefaciens virulence toward a host plant. A sodBI but not a sodBII or sodBIII mutant showed marked reduction in its ability to induce tumors on tobacco leaf discs, while the triple sod null mutant is avirulent.
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Affiliation(s)
- Panatda Saenkham
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
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Eiamphungporn W, Charoenlap N, Vattanaviboon P, Mongkolsuk S. Agrobacterium tumefaciens soxR is involved in superoxide stress protection and also directly regulates superoxide-inducible expression of itself and a target gene. J Bacteriol 2006; 188:8669-73. [PMID: 17041041 PMCID: PMC1698218 DOI: 10.1128/jb.00856-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 10/02/2006] [Indexed: 11/20/2022] Open
Abstract
Inactivation of Agrobacterium tumefaciens soxR increases sensitivity to superoxide generators. soxR expression is highly induced by superoxide stress and is autoregulated. SoxR also directly regulates the superoxide-inducible expression of atu5152. Taken together, the physiological role of soxR and the mechanism by which it regulates expression of target genes make the A. tumefaciens SoxR system different from other bacterial systems.
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Affiliation(s)
- Warawan Eiamphungporn
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
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Yuan ZC, Zaheer R, Finan TM. Phosphate limitation induces catalase expression in Sinorhizobium meliloti, Pseudomonas aeruginosa and Agrobacterium tumefaciens. Mol Microbiol 2006; 58:877-94. [PMID: 16238634 DOI: 10.1111/j.1365-2958.2005.04874.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Growth of Sinorhizobium meliloti under Pi-limiting conditions induced expression of the major H2O2-inducible catalase (HPII) gene (katA) in this organism. This transcription required the PhoB transcriptional regulator and initiated from a promoter that was distinct from the OxyR-dependent promoter which activates katA transcription in response to addition of H2O2. In N2-fixing root nodules, katA was transcribed from the OxyR- and not the PhoB-dependent promoter. This is consistent with the accumulation of reactive oxygen species (ROS) in nodules and also indicates that bacteroids within nodules are not Pi-limited. Pi-limited growth also induced expression of catalase genes in Agrobacterium tumefaciens (HPI) and Pseudomonas aeruginosa (PA4236-HPI) suggesting that this may be a widespread phenomenon. The response is not a general stress response as in both S. meliloti and P. aeruginosa increased transcription is mediated by the phosphate responsive transcriptional activator PhoB. The phenotypic consequences of this response were demonstrated in S. meliloti by the dramatic increase in H2O2 resistance of wild type but not phoB mutant cells upon growth in Pi-limiting media. Our data indicate that in S. meliloti, katA and other genes whose products are involved in protection from oxidative stress are induced upon Pi-limitation. These observations suggest that as part of the response to Pi-limitation, S. meliloti, P. aeruginosa and A. tumefaciens have evolved a capacity to increase their resistance to oxidative stress. Whether this capacity evolved because Pi-starved cells generate more ROS or whether the physiological changes that occur in the cells in response to Pi-starvation render them more sensitive to ROS remains to be established.
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Affiliation(s)
- Ze-Chun Yuan
- Center for Environmental Genomics, Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1
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Mongkolsuk S, Dubbs JM, Vattanaviboon P. Chemical modulation of physiological adaptation and cross-protective responses against oxidative stress in soil bacterium and phytopathogen, Xanthomonas. J Ind Microbiol Biotechnol 2005; 32:687-90. [PMID: 16208463 DOI: 10.1007/s10295-005-0036-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Accepted: 08/08/2005] [Indexed: 10/25/2022]
Abstract
Soil bacteria need to adapt quickly to changes in the environmental conditions. Physiological adaptation plays an important role in microbial survival, especially under stressful conditions. Here the abilities of chemicals and pesticides to modulate physiological adaptive and cross-protective responses, that make the bacteria more resistant to oxidative stress, are examined in the soil bacterium and phytopathogen, Xanthomonas. The genetic basis for the observed stress resistance, as well as the regulatory mechanisms controlling gene expression during the process, has begun to be elucidated.
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Affiliation(s)
- Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, 10210 Bangkok, Thailand.
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12
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Qiu X, Sundin GW, Wu L, Zhou J, Tiedje JM. Comparative analysis of differentially expressed genes in Shewanella oneidensis MR-1 following exposure to UVC, UVB, and UVA radiation. J Bacteriol 2005; 187:3556-64. [PMID: 15866945 PMCID: PMC1111996 DOI: 10.1128/jb.187.10.3556-3564.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously reported that Shewanella oneidensis MR-1 is highly sensitive to UVC (254 nm), UVB (290 to 320 nm), and UVA (320 to 400 nm). Here we delineated the cellular response of MR-1 to UV radiation damage by analyzing the transcriptional profile during a 1-h recovering period after UVC, UVB, and UVA exposure at a dose that yields about a 20% survival rate. Although the SOS response was observed with all three treatments, the induction was more robust in response to short-wavelength UV radiation (UVB and UVC). Similarly, more prophage-related genes were induced by short-wavelength UV radiation. MR-1 showed an active detoxification mechanism in response to UVA, which included the induction of antioxidant enzymes and iron-sequestering proteins to scavenge reactive oxygen species. In addition, a great number of genes encoding multidrug and heavy metal efflux pumps were induced following UVA irradiation. Our data suggested that activation of prophages appears the major lethal factor in MR-1 following UVC or UVB irradiation, whereas oxidative damage contributes greatly to the high UVA sensitivity in MR-1.
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Affiliation(s)
- Xiaoyun Qiu
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA
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13
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Prapagdee B, Eiamphungporn W, Saenkham P, Mongkolsuk S, Vattanaviboon P. Analysis of growth phase regulated KatA and CatE and their physiological roles in determining hydrogen peroxide resistance in Agrobacterium tumefaciens. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09699.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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14
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Prapagdee B, Vattanaviboon P, Mongkolsuk S. The role of a bifunctional catalase-peroxidase KatA in protection of Agrobacterium tumefaciens from menadione toxicity. FEMS Microbiol Lett 2004; 232:217-23. [PMID: 15033242 DOI: 10.1016/s0378-1097(04)00075-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Revised: 01/12/2004] [Accepted: 01/21/2004] [Indexed: 11/23/2022] Open
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.
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Affiliation(s)
- Benjaphorn Prapagdee
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
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