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Cassier-Chauvat C, Marceau F, Farci S, Ouchane S, Chauvat F. The Glutathione System: A Journey from Cyanobacteria to Higher Eukaryotes. Antioxidants (Basel) 2023; 12:1199. [PMID: 37371929 DOI: 10.3390/antiox12061199] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
From bacteria to plants and humans, the glutathione system plays a pleiotropic role in cell defense against metabolic, oxidative and metal stresses. Glutathione (GSH), the γ-L-glutamyl-L-cysteinyl-glycine nucleophile tri-peptide, is the central player of this system that acts in redox homeostasis, detoxification and iron metabolism in most living organisms. GSH directly scavenges diverse reactive oxygen species (ROS), such as singlet oxygen, superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide and carbon radicals. It also serves as a cofactor for various enzymes, such as glutaredoxins (Grxs), glutathione peroxidases (Gpxs), glutathione reductase (GR) and glutathione-S-transferases (GSTs), which play crucial roles in cell detoxication. This review summarizes what is known concerning the GSH-system (GSH, GSH-derived metabolites and GSH-dependent enzymes) in selected model organisms (Escherichia coli, Saccharomyces cerevisiae, Arabidopsis thaliana and human), emphasizing cyanobacteria for the following reasons. Cyanobacteria are environmentally crucial and biotechnologically important organisms that are regarded as having evolved photosynthesis and the GSH system to protect themselves against the ROS produced by their active photoautotrophic metabolism. Furthermore, cyanobacteria synthesize the GSH-derived metabolites, ergothioneine and phytochelatin, that play crucial roles in cell detoxication in humans and plants, respectively. Cyanobacteria also synthesize the thiol-less GSH homologs ophthalmate and norophthalmate that serve as biomarkers of various diseases in humans. Hence, cyanobacteria are well-suited to thoroughly analyze the role/specificity/redundancy of the players of the GSH-system using a genetic approach (deletion/overproduction) that is hardly feasible with other model organisms (E. coli and S. cerevisiae do not synthesize ergothioneine, while plants and humans acquire it from their soil and their diet, respectively).
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Affiliation(s)
- Corinne Cassier-Chauvat
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Fanny Marceau
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Sandrine Farci
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Soufian Ouchane
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Franck Chauvat
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
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Goff JL, Schaefer JK, Yee N. Extracellular sulfite is protective against reactive oxygen species and antibiotic stress in Shewanella oneidensis MR-1. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:394-400. [PMID: 33870629 DOI: 10.1111/1758-2229.12947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/04/2021] [Indexed: 06/12/2023]
Abstract
In this study, we investigated the extracellular reactive sulfur species produced by Shewanella oneidensis MR-1 during growth. The results showed that sulfite is the major extracellular sulfur metabolite released to the growth medium under both aerobic and anaerobic growth conditions. Exogenous sulfite at physiological concentrations protected S. oneidensis MR-1 from hydrogen peroxide toxicity and enhanced tolerance to the beta-lactam antibiotics cefazolin, meropenem, doripenem and ertapenem. These findings suggest that the release of extracellular sulfite is a bacterial defence mechanism that plays a role in the mitigation of environmental stress.
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Affiliation(s)
- Jennifer L Goff
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Nathan Yee
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
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Metabolic Feedback Inhibition Influences Metabolite Secretion by the Human Gut Symbiont Bacteroides thetaiotaomicron. mSystems 2020; 5:5/5/e00252-20. [PMID: 32873608 PMCID: PMC7470985 DOI: 10.1128/msystems.00252-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteroides is a highly abundant taxon in the human gut, and Bacteroides thetaiotaomicron (B. theta) is a ubiquitous human symbiont that colonizes the host early in development and persists throughout its life span. The phenotypic plasticity of keystone organisms such as B. theta is important to understand in order to predict phenotype(s) and metabolic interactions under changing nutrient conditions such as those that occur in complex gut communities. Our study shows B. theta prioritizes energy conservation and suppresses secretion of “overflow metabolites” such as organic acids and amino acids when concentrations of acetate are high. Secreted metabolites, especially amino acids, can be a source of nutrients or signals for the host or other microbes in the community. Our study suggests that when metabolically stressed by acetate, B. theta stops sharing with its ecological partners. Microbial metabolism and trophic interactions between microbes give rise to complex multispecies communities in microbe-host systems. Bacteroides thetaiotaomicron (B. theta) is a human gut symbiont thought to play an important role in maintaining host health. Untargeted nuclear magnetic resonance metabolomics revealed B. theta secretes specific organic acids and amino acids in defined minimal medium. Physiological concentrations of acetate and formate found in the human intestinal tract were shown to cause dose-dependent changes in secretion of metabolites known to play roles in host nutrition and pathogenesis. While secretion fluxes varied, biomass yield was unchanged, suggesting feedback inhibition does not affect metabolic bioenergetics but instead redirects carbon and energy to CO2 and H2. Flux balance analysis modeling showed increased flux through CO2-producing reactions under glucose-limiting growth conditions. The metabolic dynamics observed for B. theta, a keystone symbiont organism, underscores the need for metabolic modeling to complement genomic predictions of microbial metabolism to infer mechanisms of microbe-microbe and microbe-host interactions. IMPORTANCEBacteroides is a highly abundant taxon in the human gut, and Bacteroides thetaiotaomicron (B. theta) is a ubiquitous human symbiont that colonizes the host early in development and persists throughout its life span. The phenotypic plasticity of keystone organisms such as B. theta is important to understand in order to predict phenotype(s) and metabolic interactions under changing nutrient conditions such as those that occur in complex gut communities. Our study shows B. theta prioritizes energy conservation and suppresses secretion of “overflow metabolites” such as organic acids and amino acids when concentrations of acetate are high. Secreted metabolites, especially amino acids, can be a source of nutrients or signals for the host or other microbes in the community. Our study suggests that when metabolically stressed by acetate, B. theta stops sharing with its ecological partners.
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Smirnova GV, Muzyka NG, Ushakov VY, Tyulenev AV, Oktyabrsky ON. Extracellular superoxide provokes glutathione efflux from Escherichia coli cells. Res Microbiol 2015; 166:609-17. [DOI: 10.1016/j.resmic.2015.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/23/2015] [Accepted: 07/06/2015] [Indexed: 11/28/2022]
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5
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Perreault F, de Faria AF, Nejati S, Elimelech M. Antimicrobial Properties of Graphene Oxide Nanosheets: Why Size Matters. ACS NANO 2015; 9:7226-36. [PMID: 26091689 DOI: 10.1021/acsnano.5b02067] [Citation(s) in RCA: 486] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Graphene oxide (GO) is a promising material for the development of antimicrobial surfaces due to its contact-based antimicrobial activity. However, the relationship between GO physicochemical properties and its antimicrobial activity has yet to be elucidated. In this study, we investigated the size-dependency of GO antimicrobial activity using the Gram-negative bacteria Escherichia coli. GO suspensions of average sheet area ranging from 0.01 to 0.65 μm(2) were produced and their antimicrobial activity evaluated in cell suspensions or as a model GO surface coating. The antimicrobial activity of GO surface coatings increased 4-fold when GO sheet area decreased from 0.65 to 0.01 μm(2). The higher antimicrobial effect of smaller GO sheets is attributed to oxidative mechanisms associated with the higher defect density of smaller sheets. In contrast, in suspension assays, GO interacted with bacteria in a cell entrapment mechanism; in this case, the antimicrobial effect of GO increased with increasing sheet area, with apparent complete inactivation observed for the 0.65 μm(2) sheets after a 3 h exposure. However, cell inactivation by GO entrapment was reversible and all initially viable cells could be recovered when separated from GO sheets by sonication. These findings provide useful guidelines for future development of graphene-based antimicrobial surface coatings, where smaller sheet sizes can increase the antimicrobial activity of the material. Our study further emphasizes the importance of an accurate assessment of the antimicrobial effect of nanomaterials when used for antimicrobial surface design.
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Affiliation(s)
- François Perreault
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
| | - Andreia Fonseca de Faria
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
| | - Siamak Nejati
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
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Abstract
BACKGROUND Glutathione (GSH) is synthesized in the cytoplasm but there is a requirement for glutathione not only in the cytoplasm, but in the other organelles and the extracellular milieu. GSH is also imported into the cytoplasm. The transports of glutathione across these different membranes in different systems have been biochemically demonstrated. However the molecular identity of the transporters has been established only in a few cases. SCOPE OF REVIEW An attempt has been made to present the current state of knowledge of glutathione transporters from different organisms as well as different organelles. These include the most well characterized transporters, the yeast high-affinity, high-specificity glutathione transporters involved in import into the cytoplasm, and the mammalian MRP proteins involved in low affinity glutathione efflux from the cytoplasm. Other glutathione transporters that have been described either with direct or indirect evidences are also discussed. MAJOR CONCLUSIONS The molecular identity of a few glutathione transporters has been unambiguously established but there is a need to identify the transporters of other systems and organelles. There is a lack of direct evidence establishing transport by suggested transporters in many cases. Studies with the high affinity transporters have led to important structure-function insights. GENERAL SIGNIFICANCE An understanding of glutathione transporters is critical to our understanding of redox homeostasis in living cells. By presenting our current state of understanding and the gaps in our knowledge the review hopes to stimulate research in these fields. This article is part of a Special Issue entitled Cellular functions of glutathione.
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7
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Smirnova G, Muzyka N, Oktyabrsky O. Transmembrane glutathione cycling in growing Escherichia coli cells. Microbiol Res 2012; 167:166-72. [PMID: 21689911 DOI: 10.1016/j.micres.2011.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 05/17/2011] [Accepted: 05/22/2011] [Indexed: 10/18/2022]
Abstract
Glutathione (GSH) plays an important role in bacterial cells, participating in maintenance of redox balance in the cytoplasm and in defense against many toxic compounds and stresses. In this study we demonstrate that in aerobic, exponentially growing Escherichia coli culture endogenous reduced glutathione undergoes continuous transmembrane cycling between the cells and medium. As a result of an establishment of a dynamic balance between GSH efflux and uptake, a constant extracellular concentration of GSH counting per biomass unit is maintained. The magnitude of this concentration strictly depends on external pH. GSH cycling is carried out in respiring cells and disturbed by influences, which change the level of ΔμH(+) and ATP. Export of GSH is modified by phosphate deficiency in the medium.
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Affiliation(s)
- Galina Smirnova
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, ul.Goleva 13, Perm 614081, Russia.
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8
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Oktyabrskii ON, Smirnova GV. Redox potential changes in bacterial cultures under stress conditions. Microbiology (Reading) 2012. [DOI: 10.1134/s0026261712020099] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Ireland PM, LeButt H, Thomas RM, Oyston PCF. A Francisella tularensis SCHU S4 mutant deficient in γ-glutamyltransferase activity induces protective immunity: characterization of an attenuated vaccine candidate. MICROBIOLOGY-SGM 2011; 157:3172-3179. [PMID: 21852349 DOI: 10.1099/mic.0.052902-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Francisella tularensis is an intracellular pathogen which causes tularaemia. There is no licensed vaccine currently available for prophylaxis. The γ-glutamyl transpeptidase (GGT) encoded by the ggt gene has been shown to be important for the intracellular survival of F. tularensis. In this study we have constructed a ggt deletion mutant in the highly virulent F. tularensis strain SCHU S4. Characterization of the mutant strain confirmed the function of ggt, and confirmed the role of GGT in cysteine acquisition. The mutant strain was highly attenuated both in vitro and in vivo using murine models of infection. Moreover, we have demonstrated that the attenuated mutant is able to induce protective immunity against an F. tularensis SCHU S4 challenge, and thus may be a candidate for the development of an attenuated vaccine.
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Affiliation(s)
- Philip M Ireland
- Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Helen LeButt
- Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Rebecca M Thomas
- Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Petra C F Oyston
- Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
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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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11
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Kelly BS, Antholine WE, Griffith OW. Escherichia coli gamma-glutamylcysteine synthetase. Two active site metal ions affect substrate and inhibitor binding. J Biol Chem 2002; 277:50-8. [PMID: 11675389 DOI: 10.1074/jbc.m107961200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gamma-glutamylcysteine synthetase (gamma-GCS, glutamate-cysteine ligase), which catalyzes the first and rate-limiting step in glutathione biosynthesis, is present in many prokaryotes and in virtually all eukaryotes. Although all eukaryotic gamma-GCS isoforms examined to date are rapidly inhibited by buthionine sulfoximine (BSO), most reports indicate that bacterial gamma-GCS is resistant to BSO. We have confirmed the latter finding with Escherichia coli gamma-GCS under standard assay conditions, showing both decreased initial binding affinity for BSO and a reduced rate of BSO-mediated inactivation compared with mammalian isoforms. We also find that substitution of Mn2+ for Mg2+ in assay mixtures increases both the initial binding affinity of BSO and the rate at which BSO causes mechanism-based inactivation. Similarly, the specificity of E. coli gamma-GCS for its amino acid substrates is broadened in the presence of Mn2+, and the rate of reaction for some very poor substrates is improved. These results suggest that divalent metal ions have a role in amino acid binding to E. coli gamma-GCS. Electron paramagnetic resonance (EPR) studies carried out with Mn2+ show that E. coli gamma-GCS binds two divalent metal ions; Kd values for Mn2+ are 1.1 microm and 82 microm, respectively. Binding of l-glutamate or l-BSO to the two Mn2+/gamma-GCS species produces additional upfield and downfield X-band EPR hyperfine lines at 45 G intervals, a result indicating that the two Mn2+ are spin-coupled and thus apparently separated by 5 A or less in the active site. Additional EPR studies in which Cu2+ replaced Mg2+ or Mn2+ suggest that Cu2+ is bound by one N and three O ligands in the gamma-GCS active site. The results are discussed in the context of the catalytic mechanism of gamma-GCS and its relationship to the more fully characterized glutamine synthetase reaction.
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Affiliation(s)
- Brenda S Kelly
- Department of Biochemistry and Biophysics Institute, Medical College of Wisconsin, Milwaukee, Wiscosin 53226, USA
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12
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Waters MD, Stack HF, Jackson MA, Brockman HE, De Flora S. Activity profiles of antimutagens: in vitro and in vivo data. Mutat Res 1996; 350:109-29. [PMID: 8657173 DOI: 10.1016/0027-5107(95)00097-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In this review, retinol, chlorophyllin, and N-acetylcysteine are examined and compared with regard to their antimutagenic activity against some promutagens and a group of direct-acting alkylating agents. The promutagens included aflatoxin B1, certain polycyclic aromatic hydrocarbons (e.g., benzo[a]pyrene), and certain heterocyclic amines (e.g., food pyrolysates). Results of antimutagenicity testing selected from data surveyed in the published literature are displayed graphically as activity profiles of antimutagens showing both the doses tested and the extent of inhibition or enhancement of mutagenic activity. All three antimutagens are discussed in terms of their putative mechanisms of action in vitro and in vivo with emphasis on the xenobiotic metabolizing enzyme systems.
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Affiliation(s)
- M D Waters
- U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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13
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Kumaresan KR, Springhorn SS, Lacks SA. Lethal and mutagenic actions of N-methyl-N'-nitro-N-nitrosoguanidine potentiated by oxidized glutathione, a seemingly harmless substance in the cellular environment. J Bacteriol 1995; 177:3641-6. [PMID: 7601826 PMCID: PMC177078 DOI: 10.1128/jb.177.13.3641-3646.1995] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Both the lethal and the mutagenic actions of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on cells of Streptococcus pneumoniae were greatly potentiated by a component of yeast extract added to the cellular environment. This component was found to be an oxidation product of glutathione, glutathione disulfide (GSSG). At low concentrations in the medium, both GSSG and glutathione potentiated MNNG action, but at high concentrations, glutathione (and other sulfhydryl compounds) abolished the effect. Point mutations in a cellular gene conferred resistance to the potentiating effect, and they blocked uptake of either GSSG or glutathione into the cells as well. This gene apparently encodes a component of the system for glutathione transport in S. pneumoniae. The mechanism by which GSSG, an apparently innocuous substance in the environment, renders low levels of MNNG genotoxic and cytotoxic thus depends on its transport into the cell, where it is reduced by glutathione reductase and then activates intracellular MNNG. Also, it was observed that mutants of S. pneumoniae defective in DNA mismatch repair are more resistant to MNNG than are wild-type cells by a factor of 2.5.
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Affiliation(s)
- K R Kumaresan
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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Panda BB, Subhadra AV, Panda KK. Prophylaxis of antioxidants against the genotoxicity of methyl mercuric chloride and maleic hydrazide in Allium micronucleus assay. Mutat Res 1995; 343:75-84. [PMID: 7791811 DOI: 10.1016/0165-1218(95)90074-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Antioxidants, namely cysteine, 2.46 x 10(-5) M; glutathione 9.75 x 10(-6), 9.75 x 10(-4) M; vitamin C, 10(-2) M; mannitol, 5 x 10(-2) M; potassium iodide, 5 x 10(-2) M and sodium selenite, 1.73 x 10(-6) M; were tested for their prophylactic activity against the genotoxicity of methylmercuric chloride, 1.26 x 10(-6) M and maleic hydrazide, 3 x 10(-4) M in Allium micronucleus assay. Antioxidants doses were administered simultaneously or prior to the genotoxic exposures. The results from the present experiments indicated that antioxidants conferred protection against the genotoxicity of both methyl mercuric chloride and maleic hydrazide. Furthermore, the protection of GSH against methyl mercuric chloride depending on the concentration persisted for 12 h.
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Affiliation(s)
- B B Panda
- Department of Botany Berhampur University, Orissa, India
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15
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Ferricyanide reduction by Escherichia coli cells: Probable contribution of low molecular weight thiols. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0302-4598(93)80050-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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16
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Oktyabrsky ON, Golyasnaya NV, Smirnova GV, Demakov VA, Posokhina NK, Kholstova TA. Acidification of Escherichia coli and Salmonella typhimurium cytoplasm reduces the mutagenic effect of N-methyl-N'-nitro-N-nitrosoguanidine. Mutat Res 1993; 293:197-204. [PMID: 7679469 DOI: 10.1016/0921-8777(93)90070-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Preliminary acidification of the cytoplasm of E. coli cells growing at pH 6.9 by adding to the medium 50 mM of sodium acetate or propionate reduced the mutagenic effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) to almost the spontaneous level. In experiments with S. typhimurium the protective effects of cytoplasm acidification against the mutagenic effect of MNNG was observed at pH 5.5 and was absent at a medium pH of 6.9. Alkalinization of the cytoplasm by adding 80 mM of methylamine to the growth medium at pH 8.1 did not modify the effect of MNNG on the cells of E. coli and S. typhimurium. Alkalinization of the cytoplasm of E. coli B/r and K12 was followed by a reduction of the intracellular non-protein SH group level by 25 and 50%, respectively. It is supposed that the protective effect of acidification may be due to a decline in the productivity of mutagenically more active intermediates of MNNG when the pH is reduced and the associated fall of the level of intracellular non-protein thiols occurs. The above situation may serve as a model for studying the effects of MNNG and other alkylating agents on cells differing in physiological status.
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Affiliation(s)
- O N Oktyabrsky
- Laboratory of Microorganism Physiology, Russian Academy of Sciences, Perm
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17
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Hartman PE, Hartman Z. Direct interception of mutagens and carcinogens by biomolecules. BASIC LIFE SCIENCES 1993; 61:351-366. [PMID: 8304946 DOI: 10.1007/978-1-4615-2984-2_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Five points are emphasized: 1. Chemical interception and mere physical exclusion of mutagens and carcinogens constitute the major means by which mutations in cellular DNA are prevented. DNA repair processes comprise critical, but relatively minor, modes of genetic protection. 2. Disruption of a mutagen-interception defense mechanism can lead to substantial increases in mutagenesis and can preordain sites to eventual tumor formation. 3. Quantitation of the relative contributions of various blocking molecules is often simplified by the fact that protection can be calculated merely through knowledge of the measured concentration of the antimutagen and its rate of reaction with specific mutagens as measured in straightforward in vitro tests. 4. Two recently recognized defensive molecules, carnosine and ergothioneine, are put ++forward as examples of interesting chemical interceptor molecules. 5. Essentially all antimutagens are in fact "double-edged swords." Situations can be artificially constructed that can lead to generation of toxic species from molecules that are normally antimutagens; in isolated cases some of these interactions can be pictured as having deleterious consequences in vivo. This may be one reason why a number of important antimutagens are often sequestered, either in different tissues or by binding to dispensable macromolecules.
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Affiliation(s)
- P E Hartman
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218
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18
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Sheehan D, Casey JP. Microbial glutathione S-transferases. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1993; 104:1-6. [PMID: 8448982 DOI: 10.1016/0305-0491(93)90330-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- D Sheehan
- Department of Biochemistry, University College Cork, Ireland
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19
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Shankel DM, Kuo S, Haines C, Mitscher LA. Extracellular interception of mutagens. BASIC LIFE SCIENCES 1993; 61:65-74. [PMID: 8304956 DOI: 10.1007/978-1-4615-2984-2_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Extracellular interception of mutagens by excreted enzymes or by chemical agents that react with or bind to formed mutagens provides an important means of defense against chemical mutagens/carcinogens. Kada and Shimoi have classified molecules that function in this manner as "desmutagens," and many of them are natural cellular metabolites. Among the specific mechanisms that such agents may employ are: prevention of the activation of "promutagens" to mutagens; stimulation of enzymes (e.g., glutathione-S-transferase) that catalyze the binding/inactivation of damaging electrophiles; direct binding and concomitant inactivation of promutagens or mutagens; interference with uptake of mutagens into cells; etc. De Flora and Ramel have provided an excellent discussion of the mechanisms of these agents and a proposed classification scheme. Drawing on work from our own laboratories and other recent examples in the literature, several examples of mechanistic approaches to these studies using natural plant-derived materials, e.g., humic acid, Glycyrrhiza glabra extract, glutathione, and bioflavonoids, are also described. Antioxidants and agents that conjugate electrophiles will be among the modes of action described for obtaining the goal of intercepting mutagens/carcinogens.
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Affiliation(s)
- D M Shankel
- Department of Microbiology, University of Kansas, Lawrence 66045
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De Flora S, Izzotti A, Bennicelli C. Mechanisms of antimutagenesis and anticarcinogenesis: role in primary prevention. BASIC LIFE SCIENCES 1993; 61:1-16. [PMID: 8304921 DOI: 10.1007/978-1-4615-2984-2_1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S De Flora
- Institute of Hygiene and Preventive Medicine, University of Genoa, Italy
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De Flora S, Camoirano A, D'Agostini F, Balansky R. Modulation of the mutagenic response in prokaryotes. Mutat Res 1992; 267:183-92. [PMID: 1376420 DOI: 10.1016/0027-5107(92)90062-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Short-term tests investigating genetic end-points in prokaryotes have been extensively used worldwide not only for risk assessment purposes but also for evaluating the modulation of the mutagenic response. In spite of some intrinsic limitations, such as the lack of cell compartmentalization or the need for an exogenous metabolic system working extracellularly, experimental systems in bacteria can provide useful preliminary indications and some information on the mechanisms involved. In the large majority of studies the putative modulator is mixed with a known mutagen and then assayed in target bacteria, with suitable controls. However, under natural conditions exposure of target cells to modulators may either precede, co-exist with, or follow exposure to mutagens. Therefore, a variety of methodological variations, involving pre-treatment, co-treatment, or post-treatment of bacteria with the putative modulator, have been designed. Application of these procedures showed that the effects of modulators can be completely upset, from inhibition to enhancement, or vice versa, by changing the experimental conditions. Use of methodological variations may provide more complete information on the spectrum of possible effects in bacteria as well as a better insight into modulation mechanisms. Several examples illustrating the flexibility of the Salmonella test in this field of research are available. On the other hand, the widespread use of these relatively simple techniques, yet requiring skillfulness and experience, may lead to some misuse or oversimplifications. A rather common inadequacy is to use excessive amounts of test mutagens, or to express the results in terms of revertants/survivors, rather than revertants/plate. In fact, in the Salmonella test the number of revertants is rather unrelated to the initial number of plated bacteria, provided a normal background lawn of bacterial growth is formed. Thus, a 50% killing of bacteria will not appreciably influence the number of revertants/plate, but expressed as revertants/survivors the effect will look twice as large.
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Affiliation(s)
- S De Flora
- Institute of Hygiene and Preventive Medicine, University of Genoa, Italy
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22
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De Flora S, Izzotti A, D'Agostini F, Cesarone CF. Antioxidant activity and other mechanisms of thiols involved in chemoprevention of mutation and cancer. Am J Med 1991; 91:122S-130S. [PMID: 1928203 DOI: 10.1016/0002-9343(91)90295-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Our studies provide evidence that thiols, such as N-acetyl-L-cysteine, inhibit both spontaneous mutations and induced mutations in bacteria, prevent the in vivo formation of carcinogen-DNA adducts, and suppress or delay the development of tumors or preneoplastic lesions in rodents. N-Acetylcysteine and other thiols exert antioxidant activity toward superoxide anion, hydrogen peroxide, and singlet oxygen, assessed in bacterial genotoxicity models. In addition, several other mechanisms were shown to contribute to their antimutagenic and anticarcinogenic activities, in the extracellular environment and in nontarget or target cells. These mechanisms include blocking of electrophilic metabolites and of direct-acting compounds, either of endogenous or exogenous source, modulation of several xenobiotic-metabolizing pathways, and protection of DNA-dependent nuclear enzymes. Chemoprevention of mutation and cancer by thiols is particularly useful under conditions of reduced glutathione (GSH) depletion due to toxic agents or to cancer-associated viral diseases, such as acquired immunodeficiency syndrome (AIDS) or viral hepatitis B.
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Affiliation(s)
- S De Flora
- Institute of Hygiene and Preventive Medicine, University of Genoa, Italy
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23
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Moore WR, Anderson ME, Meister A, Murata K, Kimura A. Increased capacity for glutathione synthesis enhances resistance to radiation in Escherichia coli: a possible model for mammalian cell protection. Proc Natl Acad Sci U S A 1989; 86:1461-4. [PMID: 2564202 PMCID: PMC286716 DOI: 10.1073/pnas.86.5.1461] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A strain of Escherichia coli, enriched in its content of gamma-glutamylcysteine synthetase and glutathione synthetase activities by recombinant DNA techniques, is more resistant to the lethal effects of gamma-irradiation than is the corresponding wild strain. Although the gene-enriched strain has higher glutathione levels than the wild strain, the observed radioresistance appears to be associated with the increased capacity of the gene-enriched strain to synthesize glutathione when irradiated rather than to the cellular levels of glutathione per se. Thus, resistance was abolished in the presence of buthionine sulfoximine, a selective inactivator of gamma-glutamylcysteine synthetase that decreases glutathione synthesis but that does not act directly to lower cellular glutathione levels. Conclusions drawn from studies on this E. coli model system may have relevance to protection of mammalian cells by glutathione.
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Affiliation(s)
- W R Moore
- Department of Biochemistry, Cornell University Medical College, New York, NY 10021
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Sies H. [Biochemistry of thiol groups: the role of glutathione]. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 1989; 76:57-64. [PMID: 2657438 DOI: 10.1007/bf00396705] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Glutathione (GSH) comprises the bulk of the pool of free thiol groups in biological systems. Since its first description as philothione 100 years ago, there have been repeated surprises in discoveries of novel functions. Just recently the important role of thioethers with products of the lipoxygenase reaction, i.e., the leukotrienes, was revealed as mediator of physiological and pathophysiological processes. Another major function resides in detoxication, GSH being cosubstrate in the GSH-peroxidase reaction for the reduction of hydroperoxides in the defense against oxidative stress. Interest also focuses on reactions of glutathionyl radicals in protection by thiols against DNA damage resulting from ionizing radiation.
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Affiliation(s)
- H Sies
- Institut für Physiologische Chemie I der Universität, Düsseldorf
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27
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Eisenstark A. Bacterial genes involved in response to near-ultraviolet radiation. ADVANCES IN GENETICS 1989; 26:99-147. [PMID: 2683610 DOI: 10.1016/s0065-2660(08)60224-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A model of the possible pathways of activities following NUV treatment was presented in Section I and in Fig. 1. Some of the components are firmly established, some are speculative, and many are difficult to evaluate because of insufficient experimental information. Perhaps the most relevant experiments, especially concerning ozone depletion, would be to determine the mutational specificity of NUV. By selecting lacI mutants after exposing cells to NUV, and sequencing the bases of this gene, this is now feasible. There are some problems, however. The mutation frequency is normally so low that it might be difficult to distinguish NUV mutants from spontaneous mutants. However, by irradiating cells having a uvrA or uvrB mutation, the frequency of mutation above background can be increased considerably. There remains the problem as to what fraction of the observed mutations results from oxidative damage. Some of this could be clarified by comparing mutation spectra of cells treated with NUV and cells subjected to excess oxidative damage and determining what fraction results from other avenues of lesion formation in DNA. Different species of reactive oxygen could cause different kinds of DNA lesions, and, fortunately, use of appropriate mutants should allow us to sort out any differences in specificity of lesions. Also, by appropriate manipulation of quantities of endogenous photosensitizers, it might be possible to sort out the specific mutations that are caused by photodynamic action. Another avenue of research is to explore the pathways by which NUV lesions are repaired, and whether such repair is error prone or error free. Again, the use of mutants such as xthA, uvr, and polA should assist in our understanding of the specificity of the mutational events. There are now a number of examples of global control mechanisms whereby cells abruptly shift their protein synthesis pattern under environmental stress. It is important to understand whether NUV stress results in induction of one or more of the known regulatory genes, or whether another regulon might be involved. One particular aspect of regulation that remains unsolved is the role of the katF gene, which is known to regulate the xthA and katE, but it may also regulate other genes as well. A number of striking physiological events occur even at very low fluences of NUV irradiation of cells. In part, this may be related to regulon induction. However, some of these events are in need of special exploration, such as changes at the membrane level.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- A Eisenstark
- Division of Biological Sciences, University of Missouri, Columbia 65211
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De Flora S, Ramel C. Mechanisms of inhibitors of mutagenesis and carcinogenesis. Classification and overview. Mutat Res 1988; 202:285-306. [PMID: 3057362 DOI: 10.1016/0027-5107(88)90193-5] [Citation(s) in RCA: 187] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mechanisms of action of inhibitors of mutagenesis and carcinogenesis are reviewed in the light of our present knowledge. The identified mechanisms are classified into several categories and sub-categories, depending on the stage of intervention in the mutagenesis and carcinogenesis processes, and on the patterns of modulation of the host defense devices. Although a number of the known mechanisms fit into the proposed scheme, the available information on these problems is still fragmentary, and often inhibitors act through multiple mechanisms or can interact with other inhibitors. Moreover, due to the double-edged nature of many protective factors of the organism, and to the wide array of biological properties displayed by several inhibitors, the beneficial effects are in many instances counter-balanced by adverse reactions. Nevertheless, the present data-base on mechanisms of inhibitors, which is expected to grow rapidly in the near future, provides an extremely useful scientific premise for the primary prevention of mutation-related diseases. In this prospect, the elucidation of the underlying mechanisms complements the results emerging from the monitoring of protective end-points in mutagenicity and carcinogenicity test systems.
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Affiliation(s)
- S De Flora
- Institute of Hygiene and Preventive Medicine, University of Genoa, Italy
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Arca P, Rico M, Braña AF, Villar CJ, Hardisson C, Suárez JE. Formation of an adduct between fosfomycin and glutathione: a new mechanism of antibiotic resistance in bacteria. Antimicrob Agents Chemother 1988; 32:1552-6. [PMID: 3056239 PMCID: PMC175917 DOI: 10.1128/aac.32.10.1552] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Plasmid-borne resistance to fosfomycin in bacteria is due to modification of the antibiotic molecule by a glutathione S-transferase that catalyzes the formation of a covalent bond between the sulfhydryl residue of the cysteine in glutathione and the C-1 of fosfomycin. This reaction results in opening of the epoxide ring of the antibiotic to form an inactive adduct, the structure of which was confirmed by nuclear magnetic resonance. Dialyzed extracts prepared from resistant Escherichia coli strains were unable to modify fosfomycin unless exogenous glutathione was added to the reaction mixtures. Similarly, mutants defective in glutathione biosynthesis were susceptible to fosfomycin, despite harboring a resistance plasmid. Extracts of resistant but not susceptible strains could join glutathione to 1-chloro-2,4-dinitrobenzene, confirming the nature of the enzymatic activity. Adduct formation appeared to be specific for glutathione: none of the other thiols tested (cysteine, N-acetylcysteine, and dithiothreitol) could modify fosfomycin.
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Affiliation(s)
- P Arca
- Departamento de Biología Funcional, Facultad de Medicina, Universidad de Oviedo, Julian Clavería, Spain
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Eisenstark A. Mutagenic and lethal effects of near-ultraviolet radiation (290-400 nm) on bacteria and phage. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1987; 10:317-337. [PMID: 3315655 DOI: 10.1002/em.2850100311] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Despite decades of study of the effect of near-ultraviolet radiation (NUV) on bacterial cells, insights into mechanisms of deleterious alterations and subsequent recovery are just now emerging. These insights are based on observations that 1) damage by NUV may be caused by a reactive oxygen molecule, since H2O2 may be a photoproduct of NUV; 2) some, but not all, of the effects of NUV and H2O2 are interchangeable; 3) there is an inducible regulon (oxyR) that responds to oxidative stress and is involved in protection against NUV; 4) a number of NUV-sensitive mutants are defective either in the capacity to detoxify reactive oxygen molecules or to repair DNA damage caused by NUV; and 5) recovery from NUV damage may not directly involve induction of the SOS response. Since several distinctly different photoreceptors and targets are involved, it is unknown whether NUV lethality and mutagenesis result from an accumulation of damages or whether there is a particularly critical photoeffect. To fully understand the mechanisms involved, it is important to identify the chromophore(s) of NUV, the mechanism of toxic oxygen species generation, the role of the oxidative defense regulon (oxyR), the specific lesions in the DNA, and the enzymatic events of subsequent repair.
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Affiliation(s)
- A Eisenstark
- Division of Biological Sciences, University of Missouri, Columbia 65211
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