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Rasmussen T. The Potassium Efflux System Kef: Bacterial Protection against Toxic Electrophilic Compounds. MEMBRANES 2023; 13:membranes13050465. [PMID: 37233526 DOI: 10.3390/membranes13050465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/27/2023]
Abstract
Kef couples the potassium efflux with proton influx in gram-negative bacteria. The resulting acidification of the cytosol efficiently prevents the killing of the bacteria by reactive electrophilic compounds. While other degradation pathways for electrophiles exist, Kef is a short-term response that is crucial for survival. It requires tight regulation since its activation comes with the burden of disturbed homeostasis. Electrophiles, entering the cell, react spontaneously or catalytically with glutathione, which is present at high concentrations in the cytosol. The resulting glutathione conjugates bind to the cytosolic regulatory domain of Kef and trigger activation while the binding of glutathione keeps the system closed. Furthermore, nucleotides can bind to this domain for stabilization or inhibition. The binding of an additional ancillary subunit, called KefF or KefG, to the cytosolic domain is required for full activation. The regulatory domain is termed K+ transport-nucleotide binding (KTN) or regulator of potassium conductance (RCK) domain, and it is also found in potassium uptake systems or channels in other oligomeric arrangements. Bacterial RosB-like transporters and K+ efflux antiporters (KEA) of plants are homologs of Kef but fulfill different functions. In summary, Kef provides an interesting and well-studied example of a highly regulated bacterial transport system.
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Affiliation(s)
- Tim Rasmussen
- Rudolf Virchow Center and Biocenter, Institute of Biochemistry II, Julius-Maximilians-Universität Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
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2
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Hou N, Wang Q, Sun Y, Li X, Song Q, Jiang X, Li B, Zhao X, Zang H, Li D, Li C. A novel biodemulsifier of Bacillus mojavensis XH1 - Oxalate decarboxylase with the potential for demulsification of oilfield emulsion. JOURNAL OF HAZARDOUS MATERIALS 2021; 407:124737. [PMID: 33321372 DOI: 10.1016/j.jhazmat.2020.124737] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/25/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
In recent years, special attention has been devoted to biodemulsifiers as a new type of environment-friendly demulsifiers. A novel biodemulsifying oxalate decarboxylase (OxdC) secreted by Bacillus mojavensis XH1 is reported in the present study. A genome-wide comparison showed that strains with high demulsification efficiencies all possess alkane degradation genes. An analysis of the differentially expressed genes and proteins induced by different substrates showed that OxdC secreted by XH1 was an effective demulsifier. Moreover, the demulsification ability was verified by prokaryotic gene expression, knockout and complementation analyses. OxdC from XH1 exhibited a strong demulsification capacity and significantly outperformed the model protein Bacillus subtilis 168 OxdC (Yvrk), which shared a high amino acid similarity but showed limited demulsification ability. Based on a comparison of the structural characteristics, the hydrophobic amino acids on the surface of OxdC were identified as a key factor driving the favorable demulsification activity of XH1. The metabolic pathways of XH1 used liquid paraffin and glucose as substrates, illustrating that hydrocarbons are necessary for biodemulsifier secretion. The present study provides new insight into the application of OxdC as an additional genetic resource in biodemulsification.
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Affiliation(s)
- Ning Hou
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Qiaoruo Wang
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Yang Sun
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Xianyue Li
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Qiuying Song
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Xinxin Jiang
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Baoxin Li
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Xinyue Zhao
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Hailian Zang
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China
| | - Dapeng Li
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China.
| | - Chunyan Li
- College of Resources and Environment, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China.
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3
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Wongsaroj L, Saninjuk K, Romsang A, Duang-nkern J, Trinachartvanit W, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa glutathione biosynthesis genes play multiple roles in stress protection, bacterial virulence and biofilm formation. PLoS One 2018; 13:e0205815. [PMID: 30325949 PMCID: PMC6191110 DOI: 10.1371/journal.pone.0205815] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 10/02/2018] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa PAO1 contains gshA and gshB genes, which encode enzymes involved in glutathione (GSH) biosynthesis. Challenging P. aeruginosa with hydrogen peroxide, cumene hydroperoxide, and t-butyl hydroperoxide increased the expression of gshA and gshB. The physiological roles of these genes in P. aeruginosa oxidative stress, bacterial virulence, and biofilm formation were examined using P. aeruginosa ΔgshA, ΔgshB, and double ΔgshAΔgshB mutant strains. These mutants exhibited significantly increased susceptibility to methyl viologen, thiol-depleting agent, and methylglyoxal compared to PAO1. Expression of functional gshA, gshB or exogenous supplementation with GSH complemented these phenotypes, which indicates that the observed mutant phenotypes arose from their inability to produce GSH. Virulence assays using a Drosophila melanogaster model revealed that the ΔgshA, ΔgshB and double ΔgshAΔgshB mutants exhibited attenuated virulence phenotypes. An analysis of virulence factors, including pyocyanin, pyoverdine, and cell motility (swimming and twitching), showed that these levels were reduced in these gsh mutants compared to PAO1. In contrast, biofilm formation increased in mutants. These data indicate that the GSH product and the genes responsible for GSH synthesis play multiple crucial roles in oxidative stress protection, bacterial virulence and biofilm formation in P. aeruginosa.
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Affiliation(s)
- Lampet Wongsaroj
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | | | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- * E-mail:
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4
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Virk JK, Bansal P, Gupta V, Kumar S, Singh R, Rawal RK. First report of isolation of maleamic acid from natural source Polygonatum cirrhifolium—A potential chemical marker for identification. J LIQ CHROMATOGR R T 2017. [DOI: 10.1080/10826076.2017.1402185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Jaswinder Kaur Virk
- University Centre of Excellence in Research, Baba Farid University of Health Sciences, Faridkot, Punjab, India
| | - Parveen Bansal
- University Centre of Excellence in Research, Baba Farid University of Health Sciences, Faridkot, Punjab, India
| | - Vikas Gupta
- University Centre of Excellence in Research, Baba Farid University of Health Sciences, Faridkot, Punjab, India
| | - Sanjiv Kumar
- Department of AYUSH, National Medicinal Plants Board, New Delhi, India
| | - Ranjit Singh
- CT Institute of Pharmaceutical Sciences, CT Group of Institutes, Jalandhar, Punjab, India
| | - Ravindra Kumar Rawal
- Department of Pharmaceutical Chemistry & Analysis, ISF College of Pharmacy, Moga, Punjab, India
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5
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Abstract
SIGNIFICANCE Glutathione metabolism is comparable to a jigsaw puzzle with too many pieces. It is supposed to comprise (i) the reduction of disulfides, hydroperoxides, sulfenic acids, and nitrosothiols, (ii) the detoxification of aldehydes, xenobiotics, and heavy metals, and (iii) the synthesis of eicosanoids, steroids, and iron-sulfur clusters. In addition, glutathione affects oxidative protein folding and redox signaling. Here, I try to provide an overview on the relevance of glutathione-dependent pathways with an emphasis on quantitative data. Recent Advances: Intracellular redox measurements reveal that the cytosol, the nucleus, and mitochondria contain very little glutathione disulfide and that oxidative challenges are rapidly counterbalanced. Genetic approaches suggest that iron metabolism is the centerpiece of the glutathione puzzle in yeast. Furthermore, recent biochemical studies provide novel insights on glutathione transport processes and uncoupling mechanisms. CRITICAL ISSUES Which parts of the glutathione puzzle are most relevant? Does this explain the high intracellular concentrations of reduced glutathione? How can iron-sulfur cluster biogenesis, oxidative protein folding, or redox signaling occur at high glutathione concentrations? Answers to these questions not only seem to depend on the organism, cell type, and subcellular compartment but also on different ideologies among researchers. FUTURE DIRECTIONS A rational approach to compare the relevance of glutathione-dependent pathways is to combine genetic and quantitative kinetic data. However, there are still many missing pieces and too little is known about the compartment-specific repertoire and concentration of numerous metabolites, substrates, enzymes, and transporters as well as rate constants and enzyme kinetic patterns. Gathering this information might require the development of novel tools but is crucial to address potential kinetic competitions and to decipher uncoupling mechanisms to solve the glutathione puzzle. Antioxid. Redox Signal. 27, 1130-1161.
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Affiliation(s)
- Marcel Deponte
- Department of Parasitology, Ruprecht-Karls University , Heidelberg, Germany
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6
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Cellular glutathione levels in HL-60 cells during respiratory burst are not correlated with ultra-weak photon emission. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 175:291-296. [DOI: 10.1016/j.jphotobiol.2017.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/30/2017] [Accepted: 09/01/2017] [Indexed: 01/27/2023]
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7
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Roles of the glutathione- and thioredoxin-dependent systems in the Escherichia coli responses to ciprofloxacin and ampicillin. Arch Microbiol 2016; 198:913-21. [DOI: 10.1007/s00203-016-1247-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 01/13/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
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8
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Characterization of the transcriptome of Achromobacter sp. HZ01 with the outstanding hydrocarbon-degrading ability. Gene 2016; 584:185-94. [PMID: 26915487 DOI: 10.1016/j.gene.2016.02.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 01/24/2016] [Accepted: 02/20/2016] [Indexed: 12/19/2022]
Abstract
Microbial remediation has become one of the most important strategies for eliminating petroleum pollutants. Revealing the transcript maps of microorganisms with the hydrocarbon-degrading ability contributes to enhance the degradation of hydrocarbons and further improve the effectiveness of bioremediation. In this study, we characterized the transcriptome of hydrocarbon-degrading Achromobacter sp. HZ01 after petroleum treatment for 16h. A total of 38,706,280 and 38,954,413 clean reads were obtained by RNA-seq for the petroleum-treated group and control, respectively. By an effective de novo assembly, 3597 unigenes were obtained, including 3485 annotated transcripts. Petroleum treatment had significantly influenced the transcriptional profile of strain HZ01, involving 742 differentially expressed genes. A part of genes were activated to exert specific physiological functions, whereas more genes were down-regulated including specific genes related to cell motility, genes associated with glycometabolism, and genes coding for ribosomal proteins. Identification of genes related to petroleum degradation revealed that the fatty acid metabolic pathway and a part of monooxygenases and dehydrogenases were activated, whereas the TCA cycle was inactive. Additionally, terminal oxidation might be a major aerobic pathway for the degradation of n-alkanes in strain HZ01. The newly obtained data contribute to better understand the gene expression profiles of hydrocarbon-degrading microorganisms after petroleum treatment, to further investigate the genetic characteristics of strain HZ01 and other related species and to develop cost-effective and eco-friendly strategies for remediation of crude oil-polluted environments.
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D'Argenio V, Notomista E, Petrillo M, Cantiello P, Cafaro V, Izzo V, Naso B, Cozzuto L, Durante L, Troncone L, Paolella G, Salvatore F, Di Donato A. Complete sequencing of Novosphingobium sp. PP1Y reveals a biotechnologically meaningful metabolic pattern. BMC Genomics 2014; 15:384. [PMID: 24884518 PMCID: PMC4059872 DOI: 10.1186/1471-2164-15-384] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 05/08/2014] [Indexed: 11/24/2022] Open
Abstract
Background Novosphingobium sp. strain PP1Y is a marine α-proteobacterium adapted to grow at the water/fuel oil interface. It exploits the aromatic fraction of fuel oils as a carbon and energy source. PP1Y is able to grow on a wide range of mono-, poly- and heterocyclic aromatic hydrocarbons. Here, we report the complete functional annotation of the whole Novosphingobium genome. Results PP1Y genome analysis and its comparison with other Sphingomonadal genomes has yielded novel insights into the molecular basis of PP1Y’s phenotypic traits, such as its peculiar ability to encapsulate and degrade the aromatic fraction of fuel oils. In particular, we have identified and dissected several highly specialized metabolic pathways involved in: (i) aromatic hydrocarbon degradation; (ii) resistance to toxic compounds; and (iii) the quorum sensing mechanism. Conclusions In summary, the unraveling of the entire PP1Y genome sequence has provided important insight into PP1Y metabolism and, most importantly, has opened new perspectives about the possibility of its manipulation for bioremediation purposes. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-384) contains supplementary material, which is available to authorized users.
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10
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Healy J, Ekkerman S, Pliotas C, Richard M, Bartlett W, Grayer SC, Morris GM, Miller S, Booth IR, Conway SJ, Rasmussen T. Understanding the structural requirements for activators of the Kef bacterial potassium efflux system. Biochemistry 2014; 53:1982-92. [PMID: 24601535 PMCID: PMC4004266 DOI: 10.1021/bi5001118] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The potassium efflux system, Kef, protects bacteria against the detrimental effects of electrophilic compounds via acidification of the cytoplasm. Kef is inhibited by glutathione (GSH) but activated by glutathione-S-conjugates (GS-X) formed in the presence of electrophiles. GSH and GS-X bind to overlapping sites on Kef, which are located in a cytosolic regulatory domain. The central paradox of this activation mechanism is that GSH is abundant in cells (at concentrations of ∼10-20 mM), and thus, activating ligands must possess a high differential over GSH in their affinity for Kef. To investigate the structural requirements for binding of a ligand to Kef, a novel fluorescent reporter ligand, S-{[5-(dimethylamino)naphthalen-1-yl]sulfonylaminopropyl} glutathione (DNGSH), was synthesized. By competition assays using DNGSH, complemented by direct binding assays and thermal shift measurements, we show that the well-characterized Kef activator, N-ethylsuccinimido-S-glutathione, has a 10-20-fold higher affinity for Kef than GSH. In contrast, another native ligand that is a poor activator, S-lactoylglutathione, exhibits a similar Kef affinity to GSH. Synthetic ligands were synthesized to contain either rigid or flexible structures and investigated as ligands for Kef. Compounds with rigid structures and high affinity activated Kef. In contrast, flexible ligands with similar binding affinities did not activate Kef. These data provide insight into the structural requirements for Kef gating, paving the way for the development of a screen for potential therapeutic lead compounds targeting the Kef system.
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Affiliation(s)
- Jessica Healy
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford , Mansfield Road, Oxford OX1 3TA, United Kingdom
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11
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Antelmann H, Hecker M, Zuber P. Proteomic signatures uncover thiol-specific electrophile resistance mechanisms inBacillus subtilis. Expert Rev Proteomics 2014; 5:77-90. [DOI: 10.1586/14789450.5.1.77] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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12
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MexT functions as a redox-responsive regulator modulating disulfide stress resistance in Pseudomonas aeruginosa. J Bacteriol 2012; 194:3502-11. [PMID: 22544265 DOI: 10.1128/jb.06632-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
MexT is a global LysR transcriptional regulator known to modulate antibiotic resistance and virulence in Pseudomonas aeruginosa. In this study, a novel role for MexT in mediating intrinsic disulfide stress resistance was demonstrated, representing the first identified phenotype associated with inactivation of this regulator in wild-type cells. Disruption of mexT resulted in increased susceptibility to the disulfide stress elicitor diamide [diazenedicarboxylic acid bis(N,N,-di-methylamide)]. This compound is known to elicit a specific stress response via depletion of reduced glutathione and alteration of the cellular redox environment, implicating MexT in redox control. In support of this, MexT-regulated targets, including the MexEF-OprN multidrug efflux system, were induced by subinhibitory concentrations of diamide. A mexF insertion mutant also exhibited increased diamide susceptibility, implicating the MexEF-OprN efflux system in MexT-associated disulfide stress resistance. Purified MexT protein was observed to form an oligomeric complex in the presence of oxidized glutathione, with a calculated redox potential of -189 mV. This value far exceeds the thiol-disulfide redox potential of the bacterial cytoplasm, ensuring that MexT remains reduced under normal physiological conditions. MexT is activated by mutational disruption of the predicted quinone oxidoreductase encoded by mexS. Alterations in the cellular redox state were observed in a mexS mutant (PA14nfxC), supporting a model whereby the perception of MexS-associated redox signals by MexT leads to the induction of the MexEF-OprN efflux system, which, in turn, may mediate disulfide stress resistance via efflux of electrophilic compounds.
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13
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KefF, the regulatory subunit of the potassium efflux system KefC, shows quinone oxidoreductase activity. J Bacteriol 2011; 193:4925-32. [PMID: 21742892 DOI: 10.1128/jb.05272-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Escherichia coli and many other Gram-negative pathogenic bacteria protect themselves from the toxic effects of electrophilic compounds by using a potassium efflux system (Kef). Potassium efflux is coupled to the influx of protons, which lowers the internal pH and results in immediate protection. The activity of the Kef system is subject to complex regulation by glutathione and its S conjugates. Full activation of KefC requires a soluble ancillary protein, KefF. This protein has structural similarities to oxidoreductases, including human quinone reductases 1 and 2. Here, we show that KefF has enzymatic activity as an oxidoreductase, in addition to its role as the KefC activator. It accepts NADH and NADPH as electron donors and quinones and ferricyanide (in addition to other compounds) as acceptors. However, typical electrophilic activators of the Kef system, e.g., N-ethyl maleimide, are not substrates. If the enzymatic activity is disrupted by site-directed mutagenesis while retaining structural integrity, KefF is still able to activate the Kef system, showing that the role as an activator is independent of the enzyme activity. Potassium efflux assays show that electrophilic quinones are able to activate the Kef system by forming S conjugates with glutathione. Therefore, it appears that the enzymatic activity of KefF diminishes the redox toxicity of quinones, in parallel with the protection afforded by activation of the Kef system.
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Roosild TP, Castronovo S, Healy J, Miller S, Pliotas C, Rasmussen T, Bartlett W, Conway SJ, Booth IR. Mechanism of ligand-gated potassium efflux in bacterial pathogens. Proc Natl Acad Sci U S A 2010; 107:19784-9. [PMID: 21041667 PMCID: PMC2993342 DOI: 10.1073/pnas.1012716107] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gram negative pathogens are protected against toxic electrophilic compounds by glutathione-gated potassium efflux systems (Kef) that modulate cytoplasmic pH. We have elucidated the mechanism of gating through structural and functional analysis of Escherichia coli KefC. The revealed mechanism can explain how subtle chemical differences in glutathione derivatives can produce opposite effects on channel function. Kef channels are regulated by potassium transport and NAD-binding (KTN) domains that sense both reduced glutathione, which inhibits Kef activity, and glutathione adducts that form during electrophile detoxification and activate Kef. We find that reduced glutathione stabilizes an interdomain association between two KTN folds, whereas large adducts sterically disrupt this interaction. F441 is identified as the pivotal residue discriminating between reduced glutathione and its conjugates. We demonstrate a major structural change on the binding of an activating ligand to a KTN-domain protein. Analysis of the regulatory interactions suggests strategies to disrupt pathogen potassium and pH homeostasis.
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Affiliation(s)
- Tarmo P. Roosild
- Drug Development Department, Nevada Cancer Institute, Las Vegas, NV 89135
| | | | - Jess Healy
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, United Kingdom
- School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom; and
| | - Samantha Miller
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, United Kingdom
| | - Christos Pliotas
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, United Kingdom
| | - Tim Rasmussen
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, United Kingdom
| | - Wendy Bartlett
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, United Kingdom
| | - Stuart J. Conway
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Ian R. Booth
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, Scotland, United Kingdom
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15
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Ozyamak E, Black SS, Walker CA, Maclean MJ, Bartlett W, Miller S, Booth IR. The critical role of S-lactoylglutathione formation during methylglyoxal detoxification in Escherichia coli. Mol Microbiol 2010; 78:1577-90. [PMID: 21143325 PMCID: PMC3412212 DOI: 10.1111/j.1365-2958.2010.07426.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Survival of exposure to methylglyoxal (MG) in Gram-negative pathogens is largely dependent upon the operation of the glutathione-dependent glyoxalase system, consisting of two enzymes, GlxI (gloA) and GlxII (gloB). In addition, the activation of the KefGB potassium efflux system is maintained closed by glutathione (GSH) and is activated by S-lactoylGSH (SLG), the intermediate formed by GlxI and destroyed by GlxII. Escherichia coli mutants lacking GlxI are known to be extremely sensitive to MG. In this study we demonstrate that a ΔgloB mutant is as tolerant of MG as the parent, despite having the same degree of inhibition of MG detoxification as a ΔgloA strain. Increased expression of GlxII from a multicopy plasmid sensitizes E. coli to MG. Measurement of SLG pools, KefGB activity and cytoplasmic pH shows these parameters to be linked and to be very sensitive to changes in the activity of GlxI and GlxII. The SLG pool determines the activity of KefGB and the degree of acidification of the cytoplasm, which is a major determinant of the sensitivity to electrophiles. The data are discussed in terms of how cell fate is determined by the relative abundance of the enzymes and KefGB.
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Affiliation(s)
- Ertan Ozyamak
- School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
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16
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The Escherichia coli azoreductase AzoR Is involved in resistance to thiol-specific stress caused by electrophilic quinones. J Bacteriol 2009; 191:6394-400. [PMID: 19666717 DOI: 10.1128/jb.00552-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The physiological role of Escherichia coli azoreductase AzoR was studied. It was found that AzoR was capable of reducing several benzo-, naphtho-, and anthraquinone compounds, which were better substrates for AzoR than the model azo substrate methyl red. The DeltaazoR mutant displayed reduced viability when exposed to electrophilic quinones, which are capable of depleting cellular reduced glutathione (GSH). Externally added GSH can partially restore the impaired growth of the DeltaazoR mutant caused by 2-methylhydroquinone. The transcription of azoR was induced by electrophiles, including 2-methylhydroquinone, catechol, menadione, and diamide. A transcription start point was identified 44 bp upstream from the translation start point. These data indicated that AzoR is a quinone reductase providing resistance to thiol-specific stress caused by electrophilic quinones.
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17
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Leelakriangsak M, Huyen NTT, Töwe S, van Duy N, Becher D, Hecker M, Antelmann H, Zuber P. Regulation of quinone detoxification by the thiol stress sensing DUF24/MarR-like repressor, YodB in Bacillus subtilis. Mol Microbiol 2008; 67:1108-24. [PMID: 18208493 DOI: 10.1111/j.1365-2958.2008.06110.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, we showed that the MarR-type repressor YkvE (MhqR) regulates multiple dioxygenases/glyoxalases, oxidoreductases and the azoreductase encoding yvaB (azoR2) gene in response to thiol-specific stress conditions, such as diamide, catechol and 2-methylhydroquinone (MHQ). Here we report on the regulation of the yocJ (azoR1) gene encoding another azoreductase by the novel DUF24/MarR-type repressor, YodB after exposure to thiol-reactive compounds. DNA binding activity of YodB is directly inhibited by thiol-reactive compounds in vitro. Mass spectrometry identified YodB-Cys-S-adducts that are formed upon exposure of YodB to MHQ and catechol in vitro. This confirms that catechol and MHQ are auto-oxidized to toxic ortho- and para-benzoquinones which act like diamide as thiol-reactive electrophiles. Mutational analyses further showed that the conserved Cys6 residue of YodB is required for optimal repression in vivo and in vitro while substitution of all three Cys residues of YodB affects induction of azoR1 transcription. Finally, phenotype analyses revealed that both azoreductases, AzoR1 and AzoR2 confer resistance to catechol, MHQ, 1,4-benzoquinone and diamide. Thus, both azoreductases that are controlled by different regulatory mechanisms have common functions in quinone and azo-compound reduction to protect cells against the thiol reactivity of electrophiles.
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Affiliation(s)
- Montira Leelakriangsak
- Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, Beaverton, OR, USA
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Formation of N-ethylmaleimide (NEM)-glutathione conjugate and N-ethylmaleamic acid revealed by mass spectral characterization of intracellular and extracellular microbial metabolites of NEM. Appl Environ Microbiol 2007; 74:323-6. [PMID: 17981949 DOI: 10.1128/aem.01407-07] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The extracellular and intracellular metabolites formed upon exposure of activated sludge microorganisms to a sublethal concentration of N-ethylmaleimide were monitored by liquid chromatography with ion trap mass spectrometry. The metabolite N-ethylsuccinimido-S-glutathione (m/z 433) was converted rapidly to N-(2-oxoethyl)-2,2-(propionylamino)propanamide (m/z 187) and N-ethylmaleamic acid (m/z 144).
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Henriques IDS, Kelly RT, Dauphinais JL, Love NG. Activated sludge inhibition by chemical stressors--a comprehensive study. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2007; 79:940-51. [PMID: 17910361 DOI: 10.2175/106143007x156709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The effects of shock loads of 1-chloro-2,4-dinitrobenzene (CDNB); cadmium; 1-octanol; 2,4-dinitrophenol (DNP); weakly complexed cyanide; pH 5, 9, and 11; and high ammonia levels on activated sludge biomass growth, respiration rate, flocculation, chemical oxygen demand removal, dewaterability, and settleability were studied. For all chemical shocks, except ammonia and pH, concentrations that caused 15, 25, and 50% respiration inhibition were used to provide a single pulse shock to sequencing batch reactor systems containing a nitrifying or non-nitrifying biomass. Cadmium and pH 11 shocks were most detrimental to all processes, followed by CDNB. The DNP and cyanide primarily affected respiration, while pH 5, pH 9, octanol, and ammonia did not affect the treatment process to a significant extent. A chemical source-process effect matrix is provided, which we believe will aid in the development of methods that prevent and/or attenuate the effects of toxic shock loads on activated sludge systems.
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Affiliation(s)
- Inês D S Henriques
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia, USA
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Fujisawa M, Ito M, Krulwich TA. Three two-component transporters with channel-like properties have monovalent cation/proton antiport activity. Proc Natl Acad Sci U S A 2007; 104:13289-94. [PMID: 17679694 PMCID: PMC1948933 DOI: 10.1073/pnas.0703709104] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Properties of four two-component bacterial transport systems of the cation/proton antiporter-2 (CPA2) family led to suggestions that this CPA2 subset may use a channel rather than an antiport mechanism [see Booth IR, Edwards MD, Gunasekera B, Li C, Miller S (2005) in Bacterial Ion Channels, eds Kubalski A, Martinac B (Am Soc Microbiol, Washington, DC), pp 21-40]. The transporter subset includes the intensively studied glutathione-gated K(+) efflux systems from Escherichia coli, KefGB, and KefFC. KefG and KefF are ancillary proteins. They are peripheral membrane proteins that are encoded in operons with the respective transporter proteins, KefB and KefC, and are required for optimal efflux activity. The other two-component CPA2 transporters of the subset are AmhMT, an NH(4)(+) (K(+)) efflux system from alkaliphilic Bacillus pseudofirmus OF4; and YhaTU, a K(+) efflux system from Bacillus subtilis. Here a K(+)/H(+) antiport capacity was demonstrated for YhaTU, AmhMT, and KefFC in membrane vesicles from antiporter-deficient E. coli KNabc. The apparent K(m) for K(+) was in the low mM range. The peripheral protein was required for YhaU- and KefC-dependent antiport, whereas both AmhT and AmhMT exhibited antiport. KefFC had the broadest range of substrates, using Rb(+) approximately K(+)>Li(+)>Na(+). Glutathione significantly inhibited KefFC-mediated K(+)/H(+) antiport in vesicles. The inhibition was enhanced by NADH, which presumably binds to the KTN/RCK domain of KefC. The antiport mechanism accounts for the H(+) uptake involved in KefFC-mediated electrophile resistance in vivo. Because the physiological substrate of AmhMT in the alkaliphile is NH(4)(+), the results also imply that AmhMT catalyzes NH(4)(+)/H(+) antiport, which would prevent net cytoplasmic H(+) loss during NH(4)(+) efflux.
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Affiliation(s)
- Makoto Fujisawa
- *Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY 10029; and
| | - Masahiro Ito
- Faculty of Life Sciences, Toyo University, Oura-gun, Gunma 374-0193, Japan
| | - Terry A. Krulwich
- *Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY 10029; and
- To whom correspondence should be addressed. E-mail:
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Abstract
Glutathione metabolism and its role in vital functions of bacterial cells are considered, as well as common features and differences between the functions of glutathione in prokaryotic and eukaryotic cells. Particular attention is given to the recent data for the role of glutathione in bacterial redox-regulation and adaptation to stresses.
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Affiliation(s)
- G V Smirnova
- Institute of Ecology and Genetics of Microorganisms, Ural Division of the Russian Academy of Sciences, Perm, 614081, Russia.
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Rawat M, Uppal M, Newton G, Steffek M, Fahey RC, Av-Gay Y. Targeted mutagenesis of the Mycobacterium smegmatis mca gene, encoding a mycothiol-dependent detoxification protein. J Bacteriol 2004; 186:6050-8. [PMID: 15342574 PMCID: PMC515152 DOI: 10.1128/jb.186.18.6050-6058.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycothiol (MSH), a functional analogue of glutathione (GSH) that is found exclusively in actinomycetes, reacts with electrophiles and toxins to form MSH-toxin conjugates. Mycothiol S-conjugate amidase (Mca) then catalyzes the hydrolysis of an amide bond in the S conjugates, producing a mercapturic acid of the toxin, which is excreted from the bacterium, and glucosaminyl inositol, which is recycled back to MSH. In this study, we have generated and characterized an allelic exchange mutant of the mca gene of Mycobacterium smegmatis. The mca mutant accumulates the S conjugates of the thiol-specific alkylating agent monobromobimane and the antibiotic rifamycin S. Introduction of M. tuberculosis mca epichromosomally or introduction of M. smegmatis mca integratively resulted in complementation of Mca activity and reduced levels of S conjugates. The mutation in mca renders the mutant strain more susceptible to electrophilic toxins, such as N-ethylmalemide, iodoacetamide, and chlorodinitrobenzene, and to several oxidants, such as menadione and plumbagin. Additionally we have shown that the mca mutant is also more susceptible to the antituberculous antibiotic streptomycin. Mutants disrupted in genes belonging to MSH biosynthesis are also more susceptible to streptomycin, providing further evidence that Mca detoxifies streptomycin in the mycobacterial cell in an MSH-dependent manner.
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Affiliation(s)
- Mamta Rawat
- Department of Medicine, Division of Infectious Diseases, University of British Columbia, Vancouver, British Columbia V5Z 3J5, Canada
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