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Marchlewicz A, Guzik U, Smułek W, Wojcieszyńska D. Exploring the Degradation of Ibuprofen by Bacillus thuringiensis B1(2015b): The New Pathway and Factors Affecting Degradation. Molecules 2017; 22:molecules22101676. [PMID: 28991215 PMCID: PMC6151734 DOI: 10.3390/molecules22101676] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 10/06/2017] [Indexed: 11/29/2022] Open
Abstract
Ibuprofen is one of the most often detected pollutants in the environment, particularly at landfill sites and in wastewaters. Contamination with pharmaceuticals is often accompanied by the presence of other compounds which may influence their degradation. This work describes the new degradation pathway of ibuprofen by Bacillus thuringiensis B1(2015b), focusing on enzymes engaged in this process. It is known that the key intermediate which transformation limits the velocity of the degradation process is hydroxyibuprofen. As the degradation rate also depends on various factors, the influence of selected heavy metals and aromatic compounds on ibuprofen degradation by the B1(2015b) strain was examined. Based on the values of non-observed effect concentration (NOEC) it was found that the toxicity of tested metals increases from Hg(II) < Cu(II) < Cd(II) < Co(II) < Cr(VI). Despite the toxic effect of metals, the biodegradation of ibuprofen was observed. The addition of Co2+ ions into the medium significantly extended the time necessary for the complete removal of ibuprofen. It was shown that Bacillus thuringiensis B1(2015b) was able to degrade ibuprofen in the presence of phenol, benzoate, and 2-chlorophenol. Moreover, along with the removal of ibuprofen, degradation of phenol and benzoate was observed. Introduction of 4-chlorophenol into the culture completely inhibits degradation of ibuprofen.
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Affiliation(s)
- Ariel Marchlewicz
- Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, Jagiellońska 28, 40-032 Katowice, Poland.
| | - Urszula Guzik
- Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, Jagiellońska 28, 40-032 Katowice, Poland.
| | - Wojciech Smułek
- Institute of Chemical Technology and Engineering, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland.
| | - Danuta Wojcieszyńska
- Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, Jagiellońska 28, 40-032 Katowice, Poland.
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52
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Compartmentalization of Co and Mn in live cells of Escherichia coli: investigation using 60Co and 54Mn as radioindicators. J Radioanal Nucl Chem 2017. [DOI: 10.1007/s10967-017-5480-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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53
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Salusso A, Raimunda D. Defining the Roles of the Cation Diffusion Facilitators in Fe 2+/Zn 2+ Homeostasis and Establishment of Their Participation in Virulence in Pseudomonas aeruginosa. Front Cell Infect Microbiol 2017; 7:84. [PMID: 28373967 PMCID: PMC5357649 DOI: 10.3389/fcimb.2017.00084] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/02/2017] [Indexed: 12/21/2022] Open
Abstract
Transporters of the cation diffusion facilitator (CDF) family form dimers that export transition metals from the cytosol. The opportunistic pathogen Pseudomonas aeruginosa encodes three homologous CDF genes, czcD (PA0397), aitP (PA1297), and yiiP (PA3963). The three proteins are required for virulence in a plant host model. Disruption of the aitP gene leads to higher Fe2+ and Co2+ sensitivity together with an intracellular accumulation of these ions and to a decreased survival in presence of H2O2. Strains lacking czcD and yiiP showed low Zn2+ sensitivity. However, in iron-rich media and in the presence of Zn2+ these strains secreted higher levels of the iron chelator pyoverdine. Disruption of czcD and yiiP in a non-pyoverdine producer strain and lacking the Zn2+-transporting ATPase, increased the Zn2+ sensitivity and the accumulation of this ion. Most importantly, independent of the pyoverdine production strains lacking CzcD or YiiP, presented lower resistance to imipenem, ciprofloxacin, chloramphenicol, and gentamicin. These observations correlated with a lower survival rate upon EDTA-lysozyme treatment and overexpression of OprN and OprD porins. We hypothesize that while AitP is an Fe2+/Co2+ efflux transporter required for Fe2+ homeostasis, and ultimately redox stress handling, CzcD, and YiiP export Zn2+ to the periplasm for proper Zn2+-dependent signaling regulating outer membrane stability and therefore antibiotic tolerance.
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Affiliation(s)
- Agostina Salusso
- Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Investigación Médica Mercedes y Martín Ferreyra, Universidad Nacional de Córdoba Córdoba, Argentina
| | - Daniel Raimunda
- Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Investigación Médica Mercedes y Martín Ferreyra, Universidad Nacional de Córdoba Córdoba, Argentina
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54
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Bertrand RL. Iron accumulation, glutathione depletion, and lipid peroxidation must occur simultaneously during ferroptosis and are mutually amplifying events. Med Hypotheses 2017; 101:69-74. [PMID: 28351498 DOI: 10.1016/j.mehy.2017.02.017] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 01/16/2017] [Accepted: 02/27/2017] [Indexed: 01/18/2023]
Abstract
Ferroptosis is a recently discovered form of regulated necrosis that involves iron-dependent lipid peroxidation. How cells die once ferroptosis is triggered remains unclear. Ferroptosis is hypothesized to require three critical events: (1) accumulation of redox-active iron, (2) glutathione depletion, and (3) lipid peroxidation. It is proposed that these three events must unfold simultaneously because stopping any critical event also stops ferroptosis. These events are hypothesized to amplify in severity through positive feedback loops. The cause of death in ferroptosis is therefore the synergistic combination of antioxidant depletion, iron toxicity, and membrane denaturation. The relevance of these feedback loops for cancer and neurodegenerative therapies is discussed.
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Affiliation(s)
- Robert L Bertrand
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada.
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55
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Yekta SS, Skyllberg U, Danielsson Å, Björn A, Svensson BH. Chemical speciation of sulfur and metals in biogas reactors - Implications for cobalt and nickel bio-uptake processes. JOURNAL OF HAZARDOUS MATERIALS 2017; 324:110-116. [PMID: 26777110 DOI: 10.1016/j.jhazmat.2015.12.058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 12/14/2015] [Accepted: 12/28/2015] [Indexed: 06/05/2023]
Abstract
This article deals with the interrelationship between overall chemical speciation of S, Fe, Co, and Ni in relation to metals bio-uptake processes in continuous stirred tank biogas reactors (CSTBR). To address this topic, laboratory CSTBRs digesting sulfur(S)-rich stillage, as well as full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed co-digestion, were targeted. Sulfur speciation was evaluated using acid volatile sulfide extraction and X-ray absorption spectroscopy. Metal speciation was evaluated by chemical fractionation, kinetic and thermodynamic analyses. Relative Fe to S content is identified as a critical factor for chemical speciation and bio-uptake of metals. In reactors treating sewage sludge, quantity of Fe exceeds that of S, inducing Fe-dominated conditions, while sulfide dominates in laboratory and co-digestion reactors due to an excess of S over Fe. Under sulfide-dominated conditions, metals availability for microorganisms is restricted due to formation of metal-sulfide precipitates. However, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by microorganisms under sulfidic conditions. Concentrations of free metal ions and labile metal complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This in turn enhances metal adsorption on cell surfaces and bio-uptake rates.
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Affiliation(s)
- Sepehr Shakeri Yekta
- Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83 Linköping, Sweden.
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Åsa Danielsson
- Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83 Linköping, Sweden
| | - Annika Björn
- Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83 Linköping, Sweden
| | - Bo H Svensson
- Department of Thematic Studies-Environmental Change, Linköping University, SE-581 83 Linköping, Sweden
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Barwinska-Sendra A, Waldron KJ. The Role of Intermetal Competition and Mis-Metalation in Metal Toxicity. Adv Microb Physiol 2017; 70:315-379. [PMID: 28528650 DOI: 10.1016/bs.ampbs.2017.01.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The metals manganese, iron, cobalt, nickel, copper and zinc are essential for almost all bacteria, but their precise metal requirements vary by species, by ecological niche and by growth condition. Bacteria thus must acquire each of these essential elements in sufficient quantity to satisfy their cellular demand, but in excess these same elements are toxic. Metal toxicity has been exploited by humanity for centuries, and by the mammalian immune system for far longer, yet the mechanisms by which these elements cause toxicity to bacteria are not fully understood. There has been a resurgence of interest in metal toxicity in recent decades due to the problematic spread of antibiotic resistance amongst bacterial pathogens, which has led to an increased research effort to understand these toxicity mechanisms at the molecular level. A recurring theme from these studies is the role of intermetal competition in bacterial metal toxicity. In this review, we first survey biological metal usage and introduce some fundamental chemical concepts that are important for understanding bacterial metal usage and toxicity. Then we introduce a simple model by which to understand bacterial metal homeostasis in terms of the distribution of each essential metal ion within cellular 'pools', and dissect how these pools interact with each other and with key proteins of bacterial metal homeostasis. Finally, using a number of key examples from the recent literature, we look at specific metal toxicity mechanisms in model bacteria, demonstrating the role of metal-metal competition in the toxicity mechanisms of diverse essential metals.
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Affiliation(s)
- Anna Barwinska-Sendra
- Institute for Cell & Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Kevin J Waldron
- Institute for Cell & Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
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57
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Gault M, Effantin G, Rodrigue A. Ni exposure impacts the pool of free Fe and modifies DNA supercoiling via metal-induced oxidative stress in Escherichia coli K-12. Free Radic Biol Med 2016; 97:351-361. [PMID: 27375130 DOI: 10.1016/j.freeradbiomed.2016.06.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/23/2016] [Accepted: 06/28/2016] [Indexed: 12/16/2022]
Abstract
The biology of nickel has been widely studied in mammals because of its carcinogenic properties, whereas few studies have been performed in microorganisms. In the present work, changes accompanying stress caused by nickel were evaluated at the cellular level using RNA-Seq in Escherichia coli K-12. Interestingly, a very large number of genes were found to be deregulated by Ni stress. Iron and oxidative stress homeostasis maintenance were among the most highly enriched functional categories, and genes involved in periplasmic copper efflux were among the most highly upregulated. These results suggest that the deregulation of Fe and Cu homeostatic genes is caused by a release of free Cu and Fe ions in the cell which in turn activate the Cu and Fe homeostatic systems. The content of Cu was not significantly affected upon the addition of Ni to the growth medium, nor were the Cus and CopA Cu-efflux systems important for the survival of bacteria under Ni stress In contrast the addition of Ni slightly decreased the amount of cellular Fe and activated the transcription of Fur regulated genes in a Fur-dependent manner. Cu or Fe imbalance together with oxidative stress might affect the structure of DNA. Further experiments revealed that Ni alters the state of DNA folding by causing a relaxed conformation, a phenomenon that is reversible by addition of the antioxidant Tiron or the Fe chelator Dip. The Tiron-reversible DNA relaxation was also observed for Fe and to a lesser extent with Cu but not with Co. DNA supercoiling is well recognized as an integral aspect of gene regulation. Moreover our results show that Ni modifies the expression of several nucleoid-associated proteins (NAPs), important agents of DNA topology and global gene regulation. This is the first report describing the impact of metal-induced oxidative on global regulatory networks.
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Affiliation(s)
- Manon Gault
- Microbiologie, Adaptation et Pathogénie, UMR5240, INSA Lyon, Université Lyon 1, CNRS, Université de Lyon, F-69621 Villeurbanne, France
| | - Géraldine Effantin
- Microbiologie, Adaptation et Pathogénie, UMR5240, INSA Lyon, Université Lyon 1, CNRS, Université de Lyon, F-69621 Villeurbanne, France
| | - Agnès Rodrigue
- Microbiologie, Adaptation et Pathogénie, UMR5240, INSA Lyon, Université Lyon 1, CNRS, Université de Lyon, F-69621 Villeurbanne, France.
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58
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Regulation of the Cobalt/Nickel Efflux Operon dmeRF in Agrobacterium tumefaciens and a Link between the Iron-Sensing Regulator RirA and Cobalt/Nickel Resistance. Appl Environ Microbiol 2016; 82:4732-4742. [PMID: 27235438 DOI: 10.1128/aem.01262-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 05/20/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The Agrobacterium tumefaciens C58 genome harbors an operon containing the dmeR (Atu0890) and dmeF (Atu0891) genes, which encode a transcriptional regulatory protein belonging to the RcnR/CsoR family and a metal efflux protein belonging to the cation diffusion facilitator (CDF) family, respectively. The dmeRF operon is specifically induced by cobalt and nickel, with cobalt being the more potent inducer. Promoter-lacZ transcriptional fusion, an electrophoretic mobility shift assay, and DNase I footprinting assays revealed that DmeR represses dmeRF transcription through direct binding to the promoter region upstream of dmeR A strain lacking dmeF showed increased accumulation of intracellular cobalt and nickel and exhibited hypersensitivity to these metals; however, this strain displayed full virulence, comparable to that of the wild-type strain, when infecting a Nicotiana benthamiana plant model under the tested conditions. Cobalt, but not nickel, increased the expression of many iron-responsive genes and reduced the induction of the SoxR-regulated gene sodBII Furthermore, control of iron homeostasis via RirA is important for the ability of A. tumefaciens to cope with cobalt and nickel toxicity. IMPORTANCE The molecular mechanism of the regulation of dmeRF transcription by DmeR was demonstrated. This work provides evidence of a direct interaction of apo-DmeR with the corresponding DNA operator site in vitro The recognition site for apo-DmeR consists of 10-bp AT-rich inverted repeats separated by six C bases (5'-ATATAGTATACCCCCCTATAGTATAT-3'). Cobalt and nickel cause DmeR to dissociate from the dmeRF promoter, which leads to expression of the metal efflux gene dmeF This work also revealed a connection between iron homeostasis and cobalt/nickel resistance in A. tumefaciens.
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59
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Abstract
Iron-sulfur (Fe-S) clusters are fundamental to numerous biological processes in most organisms, but these protein cofactors can be prone to damage by various oxidants (e.g., O2, reactive oxygen species, and reactive nitrogen species) and toxic levels of certain metals (e.g., cobalt and copper). Furthermore, their synthesis can also be directly influenced by the level of available iron in the environment. Consequently, the cellular need for Fe-S cluster biogenesis varies with fluctuating growth conditions. To accommodate changes in Fe-S demand, microorganisms employ diverse regulatory strategies to tailor Fe-S cluster biogenesis according to their surroundings. Here, we review the mechanisms that regulate Fe-S cluster formation in bacteria, primarily focusing on control of the Isc and Suf Fe-S cluster biogenesis systems in the model bacterium Escherichia coli.
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Affiliation(s)
- Erin L Mettert
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, ,
| | - Patricia J Kiley
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, ,
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60
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Maillard AP, Künnemann S, Große C, Volbeda A, Schleuder G, Petit-Härtlein I, de Rosny E, Nies DH, Covès J. Response of CnrX from Cupriavidus metallidurans CH34 to nickel binding. Metallomics 2016; 7:622-31. [PMID: 25628016 DOI: 10.1039/c4mt00293h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Resistance to high concentration of nickel ions is mediated in Cupriavidus metallidurans by the CnrCBA transenvelope efflux complex. Expression of the cnrCBA genes is regulated by the transmembrane signal transduction complex CnrYXH. Together, the metal sensor CnrX and the transmembrane antisigma factor CnrY control the availability of the extracytoplasmic function sigma factor CnrH. Release of CnrH from sequestration by CnrY at the cytoplasmic side of the membrane depends essentially on the binding of the agonist metal ion Ni(ii) to the periplasmic metal sensor domain of CnrX. CnrH availability leads to transcription initiation at the promoters cnrYp and cnrCp and to the expression of the genes in the cnrYXHCBA nickel resistance determinant. The first steps of signal propagation by CnrX rely on subtle metal-dependent allosteric modifications. To study the nickel-mediated triggering process by CnrX, we have altered selected residues, F66, M123, and Y135, and explored the physiological consequences of these changes with respect to metal resistance, expression of a cnrCBA-lacZ reporter fusion and protein production. M123C- and Y135F-CnrXs have been further characterized in vitro by metal affinity measurements and crystallographic structure analysis. Atomic-resolution structures of metal-bound M123C- and Y135F-CnrXs showed that Ni(ii) binds two of the three canonical conformations identified and that Ni(ii) sensing likely proceeds by conformation selection.
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Affiliation(s)
- Antoine P Maillard
- Institut de Biologie Structurale, UMR 5075 CNRS-CEA-Université Grenoble-Alpes, 71, Avenue des Martyrs, 38044 Grenoble Cedex 9, France
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61
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Colaço HG, Santo PE, Matias PM, Bandeiras TM, Vicente JB. Roles of Escherichia coli ZinT in cobalt, mercury and cadmium resistance and structural insights into the metal binding mechanism. Metallomics 2016; 8:327-36. [DOI: 10.1039/c5mt00291e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Structural-functional platform unravels new roles for ZinT in cobalt, mercury and cadmium resistance, providing clues into the metal binding mechanism.
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Affiliation(s)
- H. G. Colaço
- Research Institute for Medicines (iMed.ULisboa)
- Faculty of Pharmacy
- University of Lisbon
- Portugal
| | - P. E. Santo
- Instituto de Biologia Experimental e Tecnológica
- 2781-901 Oeiras, Portugal
| | - P. M. Matias
- Instituto de Biologia Experimental e Tecnológica
- 2781-901 Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República
| | - T. M. Bandeiras
- Instituto de Biologia Experimental e Tecnológica
- 2781-901 Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República
| | - J. B. Vicente
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República
- 2780-157 Oeiras, Portugal
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62
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Abstract
This chapter focuses on transition metals. All transition metal cations are toxic-those that are essential for Escherichia coli and belong to the first transition period of the periodic system of the element and also the "toxic-only" metals with higher atomic numbers. Common themes are visible in the metabolism of these ions. First, there is transport. High-rate but low-affinity uptake systems provide a variety of cations and anions to the cells. Control of the respective systems seems to be mainly through regulation of transport activity (flux control), with control of gene expression playing only a minor role. If these systems do not provide sufficient amounts of a needed ion to the cell, genes for ATP-hydrolyzing high-affinity but low-rate uptake systems are induced, e.g., ABC transport systems or P-type ATPases. On the other hand, if the amount of an ion is in surplus, genes for efflux systems are induced. By combining different kinds of uptake and efflux systems with regulation at the levels of gene expression and transport activity, the concentration of a single ion in the cytoplasm and the composition of the cellular ion "bouquet" can be rapidly adjusted and carefully controlled. The toxicity threshold of an ion is defined by its ability to produce radicals (copper, iron, chromate), to bind to sulfide and thiol groups (copper, zinc, all cations of the second and third transition period), or to interfere with the metabolism of other ions. Iron poses an exceptional metabolic problem due its metabolic importance and the low solubility of Fe(III) compounds, combined with the ability to cause dangerous Fenton reactions. This dilemma for the cells led to the evolution of sophisticated multi-channel iron uptake and storage pathways to prevent the occurrence of unbound iron in the cytoplasm. Toxic metals like Cd2+ bind to thiols and sulfide, preventing assembly of iron complexes and releasing the metal from iron-sulfur clusters. In the unique case of mercury, the cation can be reduced to the volatile metallic form. Interference of nickel and cobalt with iron is prevented by the low abundance of these metals in the cytoplasm and their sequestration by metal chaperones, in the case of nickel, or by B12 and its derivatives, in the case of cobalt. The most dangerous metal, copper, catalyzes Fenton-like reactions, binds to thiol groups, and interferes with iron metabolism. E. coli solves this problem probably by preventing copper uptake, combined with rapid efflux if the metal happens to enter the cytoplasm.
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63
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Romsang A, Duang-nkern J, Wirathorn W, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa IscR-Regulated Ferredoxin NADP(+) Reductase Gene (fprB) Functions in Iron-Sulfur Cluster Biogenesis and Multiple Stress Response. PLoS One 2015; 10:e0134374. [PMID: 26230408 PMCID: PMC4521836 DOI: 10.1371/journal.pone.0134374] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 07/08/2015] [Indexed: 12/14/2022] Open
Abstract
P. aeruginosa (PAO1) has two putative genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. Here, the regulation of fprB expression and the protein’s physiological roles in [4Fe-4S] cluster biogenesis and stress protection are characterized. The fprB mutant has defects in [4Fe-4S] cluster biogenesis, as shown by reduced activities of [4Fe-4S] cluster-containing enzymes. Inactivation of the gene resulted in increased sensitivity to oxidative, thiol, osmotic and metal stresses compared with the PAO1 wild type. The increased sensitivity could be partially or completely suppressed by high expression of genes from the isc operon, which are involved in [Fe-S] cluster biogenesis, indicating that stress sensitivity in the fprB mutant is partially caused by a reduction in levels of [4Fe-4S] clusters. The pattern and regulation of fprB expression are in agreement with the gene physiological roles; fprB expression was highly induced by redox cycling drugs and diamide and was moderately induced by peroxides, an iron chelator and salt stress. The stress-induced expression of fprB was abolished by a deletion of the iscR gene. An IscR DNA-binding site close to fprB promoter elements was identified and confirmed by specific binding of purified IscR. Analysis of the regulation of fprB expression supports the role of IscR in directly regulating fprB transcription as a transcription activator. The combination of IscR-regulated expression of fprB and the fprB roles in response to multiple stressors emphasizes the importance of [Fe-S] cluster homeostasis in both gene regulation and stress protection.
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Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Wilaiwan Wirathorn
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology (EHT), Ministry Of Education, Bangkok, Thailand
- * E-mail:
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64
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Karve SM, Daniel S, Chavhan YD, Anand A, Kharola SS, Dey S. Escherichia coli populations in unpredictably fluctuating environments evolve to face novel stresses through enhanced efflux activity. J Evol Biol 2015; 28:1131-43. [PMID: 25865653 DOI: 10.1111/jeb.12640] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 04/07/2015] [Indexed: 12/12/2022]
Abstract
There is considerable understanding about how laboratory populations respond to predictable (constant or deteriorating environment) selection for single environmental variables such as temperature or pH. However, such insights may not apply when selection environments comprise multiple variables that fluctuate unpredictably, as is common in nature. To address this issue, we grew replicate laboratory populations of Escherichia coli in nutrient broth whose pH and concentrations of salt (NaCl) and hydrogen peroxide (H2 O2 ) were randomly changed daily. After ~170 generations, the fitness of the selected populations had not increased in any of the three selection environments. However, these selected populations had significantly greater fitness in four novel environments which have no known fitness-correlation with tolerance to pH, NaCl or H2 O2 . Interestingly, contrary to expectations, hypermutators did not evolve. Instead, the selected populations evolved an increased ability for energy-dependent efflux activity that might enable them to throw out toxins, including antibiotics, from the cell at a faster rate. This provides an alternate mechanism for how evolvability can evolve in bacteria and potentially lead to broad-spectrum antibiotic resistance, even in the absence of prior antibiotic exposure. Given that environmental variability is increasing in nature, this might have serious consequences for public health.
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Affiliation(s)
- S M Karve
- Population Biology Laboratory, Biology Division, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - S Daniel
- Population Biology Laboratory, Biology Division, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - Y D Chavhan
- Population Biology Laboratory, Biology Division, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - A Anand
- Population Biology Laboratory, Biology Division, Indian Institute of Science Education and Research, Pune, Maharashtra, India.,Indian Institute of Science Education and Research-Kolkata, Mohanpur, West Bengal, India
| | - S S Kharola
- Population Biology Laboratory, Biology Division, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - S Dey
- Population Biology Laboratory, Biology Division, Indian Institute of Science Education and Research, Pune, Maharashtra, India
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65
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Anjum NA, Singh HP, Khan MIR, Masood A, Per TS, Negi A, Batish DR, Khan NA, Duarte AC, Pereira E, Ahmad I. Too much is bad--an appraisal of phytotoxicity of elevated plant-beneficial heavy metal ions. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:3361-82. [PMID: 25408077 DOI: 10.1007/s11356-014-3849-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/10/2014] [Indexed: 05/20/2023]
Abstract
Heavy metal ions such as cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn) are considered essential/beneficial for optimal plant growth, development, and productivity. However, these ions readily impact functions of many enzymes and proteins, halt metabolism, and exhibit phytotoxicity at supra-optimum supply. Nevertheless, the concentrations of these heavy metal ions are increasing in agricultural soils worldwide via both natural and anthropogenic sources that need immediate attention. Considering recent breakthroughs on Co, Cu, Fe, Mn, Mo, Ni, and Zn in soil-plant system, the present paper: (a) overviews the status in soils and their uptake, transport, and significance in plants; (b) critically discusses their elevated level-mediated toxicity to both plant growth/development and cell/genome; (c) briefly cross talks on the significance of potential interactions between previous plant-beneficial heavy metal ions in plants; and (d) highlights so far unexplored aspects in the current context.
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Affiliation(s)
- Naser A Anjum
- Centre for Environmental and Marine Studies (CESAM) and Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal,
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66
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What a difference a cluster makes: The multifaceted roles of IscR in gene regulation and DNA recognition. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1101-12. [PMID: 25641558 DOI: 10.1016/j.bbapap.2015.01.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 01/21/2015] [Indexed: 11/22/2022]
Abstract
Iron-sulfur clusters are essential cofactors in a myriad of metabolic pathways. Therefore, their biogenesis is tightly regulated across a variety of organisms and environmental conditions. In Gram-negative bacteria, two pathways - ISC and SUF - concur for maintaining intracellular iron-sulfur cluster balance. Recently, the mechanism of iron-sulfur cluster biosynthesis regulation by IscR, an iron-sulfur cluster-containing regulator encoded by the isc operon, was found to be conserved in some Gram-positive bacteria. Belonging to the Rrf2 family of transcriptional regulators, IscR displays a single helix-turn-helix DNA-binding domain but is able to recognize two distinct DNA sequence motifs, switching its specificity upon cluster ligation. This review provides an overview of gene regulation by iron-sulfur cluster-containing sensors, in the light of the recent structural characterization of cluster-less free and DNA-bound IscR, which provided insights into the molecular mechanism of nucleotide sequence recognition and discrimination of this unique transcription factor. This article is part of a Special Issue entitled: Cofactor-dependent proteins: evolution, chemical diversity and bio-applications.
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67
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Li Q, Csetenyi L, Gadd GM. Biomineralization of metal carbonates by Neurospora crassa. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:14409-14416. [PMID: 25423300 DOI: 10.1021/es5042546] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this research, the urease-positive fungus Neurospora crassa was investigated for the biomineralization of calcium carbonate and its potential application in metal biorecovery and/or bioremediation. After 12 d incubation at 25 °C in urea and calcium-containing medium, extensive biomineralization of fungal filaments was observed. Energy dispersive X-ray analysis of crystalline precipitates on the hyphae of N. crassa showed that the main elements present in the crystals were Ca, C, and O. X-ray diffraction (XRD) of the precipitates showed they were composed solely of calcite (CaCO3) and over 90% Ca could be removed from the media by the fungal biomass and associated calcite precipitation. To further investigate biologically induced metal carbonate biomineralization, CdCl2 was contacted with supernatants of N. crassa obtained after growth in urea-containing medium. XRD showed that the Cd(2+) was precipitated as pure otavite (CdCO3) with a particle size range of 55 to 870 nm, and approximately 1.5% having nanoscale dimensions. These results provide direct experimental evidence for the precipitation of metal carbonates such as calcite and otavite based on biologically induced mineralization, and suggest that urease-positive fungi may play a potential role in the synthesis of novel biominerals and in metal bioremediation or biorecovery.
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Affiliation(s)
- Qianwei Li
- Geomicrobiology Group, College of Life Sciences, University of Dundee , Dundee, DD1 5EH, Scotland, United Kingdom
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68
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Valentín-Vargas A, Root RA, Neilson JW, Chorover J, Maier RM. Environmental factors influencing the structural dynamics of soil microbial communities during assisted phytostabilization of acid-generating mine tailings: a mesocosm experiment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 500-501:314-24. [PMID: 25237788 PMCID: PMC4253589 DOI: 10.1016/j.scitotenv.2014.08.107] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/27/2014] [Accepted: 08/27/2014] [Indexed: 04/13/2023]
Abstract
Compost-assisted phytostabilization has recently emerged as a robust alternative for reclamation of metalliferous mine tailings. Previous studies suggest that root-associated microbes may be important for facilitating plant establishment on the tailings, yet little is known about the long-term dynamics of microbial communities during reclamation. A mechanistic understanding of microbial community dynamics in tailings ecosystems undergoing remediation is critical because these dynamics profoundly influence both the biogeochemical weathering of tailings and the sustainability of a plant cover. Here we monitor the dynamics of soil microbial communities (i.e. bacteria, fungi, archaea) during a 12-month mesocosm study that included 4 treatments: 2 unplanted controls (unamended and compost-amended tailings) and 2 compost-amended seeded tailings treatments. Bacterial, fungal and archaeal communities responded distinctively to the revegetation process and concurrent changes in environmental conditions and pore water chemistry. Compost addition significantly increased microbial diversity and had an immediate and relatively long-lasting buffering-effect on pH, allowing plants to germinate and thrive during the early stages of the experiment. However, the compost buffering capacity diminished after six months and acidification took over as the major factor affecting plant survival and microbial community structure. Immediate changes in bacterial communities were observed following plant establishment, whereas fungal communities showed a delayed response that apparently correlated with the pH decline. Fluctuations in cobalt pore water concentrations, in particular, had a significant effect on the structure of all three microbial groups, which may be linked to the role of cobalt in metal detoxification pathways. The present study represents, to our knowledge, the first documentation of the dynamics of the three major microbial groups during revegetation of compost-amended, metalliferous mine tailings.
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Affiliation(s)
- Alexis Valentín-Vargas
- Department of Soil, Water and Environmental Science, 429 Shantz Bldg. #38, 1177 E. Fourth Street, University of Arizona, Tucson, AZ 85721-0038, USA.
| | - Robert A Root
- Department of Soil, Water and Environmental Science, 429 Shantz Bldg. #38, 1177 E. Fourth Street, University of Arizona, Tucson, AZ 85721-0038, USA.
| | - Julia W Neilson
- Department of Soil, Water and Environmental Science, 429 Shantz Bldg. #38, 1177 E. Fourth Street, University of Arizona, Tucson, AZ 85721-0038, USA.
| | - Jon Chorover
- Department of Soil, Water and Environmental Science, 429 Shantz Bldg. #38, 1177 E. Fourth Street, University of Arizona, Tucson, AZ 85721-0038, USA.
| | - Raina M Maier
- Department of Soil, Water and Environmental Science, 429 Shantz Bldg. #38, 1177 E. Fourth Street, University of Arizona, Tucson, AZ 85721-0038, USA.
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69
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Outten FW. Recent advances in the Suf Fe-S cluster biogenesis pathway: Beyond the Proteobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1464-9. [PMID: 25447545 DOI: 10.1016/j.bbamcr.2014.11.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 10/31/2014] [Accepted: 11/03/2014] [Indexed: 01/21/2023]
Abstract
Fe-S clusters play critical roles in cellular function throughout all three kingdoms of life. Consequently, Fe-S cluster biogenesis systems are present in most organisms. The Suf (sulfur formation) system is the most ancient of the three characterized Fe-S cluster biogenesis pathways, which also include the Isc and Nif systems. Much of the first work on the Suf system took place in Gram-negative Proteobacteria used as model organisms. These early studies led to a wealth of biochemical, genetic, and physiological information on Suf function. From those studies we have learned that SufB functions as an Fe-S scaffold in conjunction with SufC (and in some cases SufD). SufS and SufE together mobilize sulfur for cluster assembly and SufA traffics the complete Fe-S cluster from SufB to target apo-proteins. However, recent progress on the Suf system in other organisms has opened up new avenues of research and new hypotheses about Suf function. This review focuses primarily on the most recent discoveries about the Suf pathway and where those new models may lead the field. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
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Affiliation(s)
- F Wayne Outten
- University of South Carolina, Department of Chemistry and Biochemistry, 631 Sumter Street, Columbia, SC 29208, USA.
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Abstract
The metal binding preferences of most metalloproteins do not match their metal requirements. Thus, metallation of an estimated 30% of metalloenzymes is aided by metal delivery systems, with ∼ 25% acquiring preassembled metal cofactors. The remaining ∼ 70% are presumed to compete for metals from buffered metal pools. Metallation is further aided by maintaining the relative concentrations of these pools as an inverse function of the stabilities of the respective metal complexes. For example, magnesium enzymes always prefer to bind zinc, and these metals dominate the metalloenzymes without metal delivery systems. Therefore, the buffered concentration of zinc is held at least a million-fold below magnesium inside most cells.
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Affiliation(s)
- Andrew W Foster
- From the Department of Chemistry and School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
| | - Deenah Osman
- From the Department of Chemistry and School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
| | - Nigel J Robinson
- From the Department of Chemistry and School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
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Kardas M, Gozen AG, Severcan F. FTIR spectroscopy offers hints towards widespread molecular changes in cobalt-acclimated freshwater bacteria. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 155:15-23. [PMID: 24964200 DOI: 10.1016/j.aquatox.2014.05.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/22/2014] [Accepted: 05/22/2014] [Indexed: 06/03/2023]
Abstract
High concentrations of heavy metals can be toxic for bacteria. However, after prolonged exposure, bacteria can become acclimated and begin to be able to grow in the presence of heavy metals. Acclimation can involve alterations of metabolism and molecular structures. Our aim was to examine these alterations in cobalt-acclimated bacteria via attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy on viable samples. Bacillus sp. and Pseudomonas sp. isolated from a temperate shallow lake and a well-established strain of E. coli were investigated. Our results revealed consistent, wide-spread changes in cell membrane and cell wall dynamics of Bacillus sp. and E. coli, including a decrease in peptidoglycan content of Bacillus sp. and increased lipid ordering of the membrane in both bacteria. Furthermore, a decrease in RNA and protein concentrations of Bacillus sp. was measured. All three bacteria studied showed a decrease in conformational freedom of proteins following cobalt acclimation. Interestingly, both Bacillus sp. and E. coli showed slight but significant alterations in their DNA conformations which might imply a methylation-mediated memory formation leading to epigenetic modulation for cobalt adaptation.
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Affiliation(s)
- Mehmet Kardas
- Middle East Technical University, Biological Sciences, Microbial Ecology Laboratory and Biophysics Laboratory, Ankara 06800, Turkey
| | - Ayse Gul Gozen
- Middle East Technical University, Biological Sciences, Microbial Ecology Laboratory and Biophysics Laboratory, Ankara 06800, Turkey.
| | - Feride Severcan
- Middle East Technical University, Biological Sciences, Microbial Ecology Laboratory and Biophysics Laboratory, Ankara 06800, Turkey
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72
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Coordinate regulation of the Suf and Isc Fe-S cluster biogenesis pathways by IscR is essential for viability of Escherichia coli. J Bacteriol 2014; 196:4315-23. [PMID: 25266384 DOI: 10.1128/jb.01975-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fe-S cluster biogenesis is essential for the viability of most organisms. In Escherichia coli, this process requires either the housekeeping Isc or the stress-induced Suf pathway. The global regulator IscR coordinates cluster synthesis by repressing transcription of the isc operon by [2Fe-2S]-IscR and activating expression of the suf operon. We show that either [2Fe-2S]-IscR or apo-IscR can activate suf, making expression sensitive to mainly IscR levels and not the cluster state, unlike isc expression. We also demonstrate that in the absence of isc, IscR-dependent suf activation is essential since strains lacking both the Isc pathway and IscR were not viable unless Suf was expressed ectopically. Similarly, removal of the IscR binding site in the sufA promoter also led to a requirement for isc. Furthermore, suf expression was increased in a Δisc mutant, presumably due to increased IscR levels in this mutant. This was surprising because the iron-dependent repressor Fur, whose higher-affinity binding at the sufA promoter should occlude IscR binding, showed only partial repression. In addition, Fur derepression was not sufficient for viability in the absence of IscR and the Isc pathway, highlighting the importance of direct IscR activation. Finally, a mutant lacking Fur and the Isc pathway increased suf expression to the highest observed levels and nearly restored [2Fe-2S]-IscR activity, providing a mechanism for regulating IscR activity under stress conditions. Together, these findings have enhanced our understanding of the homeostatic mechanism by which cells use one regulator, IscR, to differentially control Fe-S cluster biogenesis pathways to ensure viability.
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73
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Raimunda D, Elso-Berberián G. Functional characterization of the CDF transporter SMc02724 (SmYiiP) in Sinorhizobium meliloti: Roles in manganese homeostasis and nodulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:3203-11. [PMID: 25242380 DOI: 10.1016/j.bbamem.2014.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 09/11/2014] [Accepted: 09/12/2014] [Indexed: 01/29/2023]
Abstract
In bacteria, membrane transporters of the cation diffusion facilitator (CDF) family participate in Zn(2+), Fe(2+), Mn(2+), Co(2+) and Ni(2+) homeostasis. The functional role during infection processes for several members has been shown to be linked to the specificity of transport. Sinorhizobium meliloti has two homologous CDF genes with unknown transport specificity. Here we evaluate the role played by the CDF SMc02724 (SmYiiP). The deletion mutant strain of SmYiiP (ΔsmyiiP) showed reduced in vitro growth fitness only in the presence of Mn(2+). Incubation of ΔsmyiiP and WT cells with sub-lethal Mn(2+) concentrations resulted in a 2-fold increase of the metal only in the mutant strain. Normal levels of resistance to Mn(2+) were attained by complementation with the gene SMc02724 under regulation of its endogenous promoter. In vitro, liposomes with incorporated heterologously expressed pure protein accumulated several transition metals. However, only the transport rate of Mn(2+) was increased by imposing a transmembrane H(+) gradient. Nodulation assays in alfalfa plants showed that the strain ΔsmyiiP induced a lower number of nodules than in plants infected with the WT strain. Our results indicate that Mn(2+) homeostasis in S. meliloti is required for full infection capacity, or nodule function, and that the specificity of transport in vivo of SmYiiP is narrowed down to Mn(2+) by a mechanism involving the proton motive force.
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Affiliation(s)
- Daniel Raimunda
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Graciela Elso-Berberián
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
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Dekker L, Osborne TH, Santini JM. Isolation and identification of cobalt- and caesium-resistant bacteria from a nuclear fuel storage pond. FEMS Microbiol Lett 2014; 359:81-4. [DOI: 10.1111/1574-6968.12562] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 07/25/2014] [Accepted: 07/27/2014] [Indexed: 11/28/2022] Open
Affiliation(s)
- Linda Dekker
- Institute of Structural and Molecular Biology; University College London; London UK
| | - Thomas H. Osborne
- Institute of Structural and Molecular Biology; University College London; London UK
| | - Joanne M. Santini
- Institute of Structural and Molecular Biology; University College London; London UK
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75
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Chivers PT. Cobalt and Nickel. BINDING, TRANSPORT AND STORAGE OF METAL IONS IN BIOLOGICAL CELLS 2014. [DOI: 10.1039/9781849739979-00381] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cobalt and nickel play key roles in biological systems as cofactors in a small number of important enzymes. The majority of these are found in microbes. Evidence for direct roles for Ni(II) and Co(II) enzymes in higher organisms is limited, with the exception of the well-known requirement for the cobalt-containing vitamin B12 cofactor and the Ni-dependent urease in plants. Nonetheless, nickel in particular plays a key role in human health because of its essential role in microbes that inhabit various growth niches within the body. These roles can be beneficial, as can be seen with the anaerobic production and consumption of H2 in the digestive tract by bacteria and archaea that results in increased yields of short-chain fatty acids. In other cases, nickel has an established role in the establishment of pathogenic infection (Helicobacter pylori urease and colonization of the stomach). The synthesis of Co- and Ni-containing enzymes requires metal import from the extracellular milieu followed by the targeting of these metals to the appropriate protein and enzymes involved in metallocluster or cofactor biosynthesis. These metals are toxic in excess so their levels must be regulated carefully. This complex pathway of metalloenzyme synthesis and intracellular homeostasis requires proteins that can specifically recognize these metals in a hierarchical manner. This chapter focuses on quantitative and structural details of the cobalt and nickel binding sites in transport, trafficking and regulatory proteins involved in cobalt and nickel metabolism in microbes.
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Affiliation(s)
- Peter T. Chivers
- Department of Chemistry, School of Biological and Biomedical Sciences, and Biophysical Sciences Institute, Durham University Durham UK
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76
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Peng F, Mi Z, Huang Y, Yuan X, Niu W, Wang Y, Hua Y, Fan H, Bai C, Tong Y. Characterization, sequencing and comparative genomic analysis of vB_AbaM-IME-AB2, a novel lytic bacteriophage that infects multidrug-resistant Acinetobacter baumannii clinical isolates. BMC Microbiol 2014; 14:181. [PMID: 24996449 PMCID: PMC4094691 DOI: 10.1186/1471-2180-14-181] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Accepted: 06/25/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND With the use of broad-spectrum antibiotics, immunosuppressive drugs, and glucocorticoids, multidrug-resistant Acinetobacter baumannii (MDR-AB) has become a major nosocomial pathogen species. The recent renaissance of bacteriophage therapy may provide new treatment strategies for combatting drug-resistant bacterial infections. In this study, we isolated a lytic bacteriophage vB_AbaM-IME-AB2 has a short latent period and a small burst size, which clear its host's suspension quickly, was selected for characterization and a complete genomic comparative study. RESULTS The isolated bacteriophage vB_AbaM-IME-AB2 has an icosahedral head and displays morphology resembling Myoviridae family. Gel separation assays showed that the phage particle contains at least nine protein bands with molecular weights ranging 15-100 kDa. vB_AbaM-IME-AB2 could adsorb its host cells in 9 min with an adsorption rate more than 99% and showed a short latent period (20 min) and a small burst size (62 pfu/cell). It could form clear plaques in the double-layer assay and clear its host's suspension in just 4 hours. Whole genome of vB_AbaM-IME-AB2 was sequenced and annotated and the results showed that its genome is a double-stranded DNA molecule consisting of 43,665 nucleotides. The genome has a G + C content of 37.5% and 82 putative coding sequences (CDSs). We compared the characteristics and complete genome sequence of all known Acinetobacter baumannii bacteriophages. There are only three that have been sequenced Acinetobacter baumannii phages AB1, AP22, and phiAC-1, which have a relatively high similarity and own a coverage of 65%, 50%, 8% respectively when compared with our phage vB_AbaM-IME-AB2. A nucleotide alignment of the four Acinetobacter baumannii phages showed that some CDSs are similar, with no significant rearrangements observed. Yet some sections of these strains of phage are nonhomologous. CONCLUSION vB_AbaM-IME-AB2 was a novel and unique A. baumannii bacteriophage. These findings suggest a common ancestry and microbial diversity and evolution. A clear understanding of its characteristics and genes is conducive to the treatment of multidrug-resistant A. baumannii in the future.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Changqing Bai
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China.
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Gómez-Sagasti MT, Becerril JM, Martín I, Epelde L, Garbisu C. cDNA microarray assessment of early gene expression profiles in Escherichia coli cells exposed to a mixture of heavy metals. Cell Biol Toxicol 2014; 30:207-32. [DOI: 10.1007/s10565-014-9281-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 06/12/2014] [Indexed: 12/30/2022]
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Sun X, Yu G, Xu Q, Li N, Xiao C, Yin X, Cao K, Han J, He QY. Putative cobalt- and nickel-binding proteins and motifs in Streptococcus pneumoniae. Metallomics 2014; 5:928-35. [PMID: 23775531 DOI: 10.1039/c3mt00126a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cobalt and nickel play important roles in various biological processes. The present work focuses on the enrichment and identification of Co- and Ni-binding motifs and proteins in Gram-positive bacteria. Immobilized metal affinity column (IMAC) was used to partially enrich putative metal-binding proteins and peptides from Streptococcus pneumoniae, and then LTQ-Orbitrap mass spectrometry (MS) was applied to identify and characterize the metal-binding motifs and proteins. In total, 208 and 223 proteins were isolated by Co- and Ni-IMAC columns respectively, in which 129 proteins were present in both preparations. Based on the gene ontology (GO) analysis, the putative metal-binding proteins were found to be mainly involved in protein metabolism, gene expression regulation and carbohydrate metabolism. These putative metal-binding proteins form a highly connected network, indicating that they may synergistically work together to achieve specific biological functions. Putative Co- and Ni-binding motifs were identified with H(X)nH, M(X)nH and H(X)nM derived from the identified 51 Co-binding peptides and 66 Ni-binding peptides. Statistics of frequency of amino acids in the metal-binding motifs showed that cobalt and nickel prefer to bind histidine and methionine, but not cysteine. These results obtained by a systematic metalloproteomic approach provide important clues for the further investigation of metal homeostasis and metal-related virulence of bacteria.
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Affiliation(s)
- Xuesong Sun
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China.
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Rubio-Sanz L, Prieto RI, Imperial J, Palacios JM, Brito B. Functional and expression analysis of the metal-inducible dmeRF system from Rhizobium leguminosarum bv. viciae. Appl Environ Microbiol 2013; 79:6414-22. [PMID: 23934501 PMCID: PMC3811197 DOI: 10.1128/aem.01954-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 08/06/2013] [Indexed: 02/04/2023] Open
Abstract
A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel- and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria.
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Affiliation(s)
- L. Rubio-Sanz
- Centro de Biotecnología y Genómica de Plantas (CBGP) and Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
| | - R. I. Prieto
- Centro de Biotecnología y Genómica de Plantas (CBGP) and Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
| | - J. Imperial
- Centro de Biotecnología y Genómica de Plantas (CBGP) and Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - J. M. Palacios
- Centro de Biotecnología y Genómica de Plantas (CBGP) and Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
| | - B. Brito
- Centro de Biotecnología y Genómica de Plantas (CBGP) and Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
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Reprint of: Iron/sulfur proteins biogenesis in prokaryotes: formation, regulation and diversity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:923-37. [PMID: 23660107 DOI: 10.1016/j.bbabio.2013.05.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/21/2012] [Accepted: 12/27/2012] [Indexed: 12/15/2022]
Abstract
Iron/sulfur centers are key cofactors of proteins intervening in multiple conserved cellular processes, such as gene expression, DNA repair, RNA modification, central metabolism and respiration. Mechanisms allowing Fe/S centers to be assembled, and inserted into polypeptides have attracted much attention in the last decade, both in eukaryotes and prokaryotes. Basic principles and recent advances in our understanding of the prokaryotic Fe/S biogenesis ISC and SUF systems are reviewed in the present communication. Most studies covered stem from investigations in Escherichia coli and Azotobacter vinelandii. Remarkable insights were brought about by complementary structural, spectroscopic, biochemical and genetic studies. Highlights of the recent years include scaffold mediated assembly of Fe/S cluster, A-type carriers mediated delivery of clusters and regulatory control of Fe/S homeostasis via a set of interconnected genetic regulatory circuits. Also, the importance of Fe/S biosynthesis systems in mediating soft metal toxicity was documented. A brief account of the Fe/S biosynthesis systems diversity as present in current databases is given here. Moreover, Fe/S biosynthesis factors have themselves been the object of molecular tailoring during evolution and some examples are discussed here. An effort was made to provide, based on the E. coli system, a general classification associating a given domain with a given function such as to help next search and annotation of genomes. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
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81
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Addition of Co2+ to culture medium decides the functional expression of a recombinant nitrile hydratase in Escherichia coli. Biotechnol Lett 2013; 35:1419-24. [DOI: 10.1007/s10529-013-1215-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 04/09/2013] [Indexed: 10/26/2022]
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82
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Roselli S, Nadalig T, Vuilleumier S, Bringel F. The 380 kb pCMU01 plasmid encodes chloromethane utilization genes and redundant genes for vitamin B12- and tetrahydrofolate-dependent chloromethane metabolism in Methylobacterium extorquens CM4: a proteomic and bioinformatics study. PLoS One 2013; 8:e56598. [PMID: 23593113 PMCID: PMC3621897 DOI: 10.1371/journal.pone.0056598] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/11/2013] [Indexed: 12/24/2022] Open
Abstract
Chloromethane (CH3Cl) is the most abundant volatile halocarbon in the atmosphere and contributes to the destruction of stratospheric ozone. The only known pathway for bacterial chloromethane utilization (cmu) was characterized in Methylobacterium extorquens CM4, a methylotrophic bacterium able to utilize compounds without carbon-carbon bonds such as methanol and chloromethane as the sole carbon source for growth. Previous work demonstrated that tetrahydrofolate and vitamin B12 are essential cofactors of cmuA- and cmuB-encoded methyltransferases of chloromethane dehalogenase, and that the pathway for chloromethane utilization is distinct from that for methanol. This work reports genomic and proteomic data demonstrating that cognate cmu genes are located on the 380 kb pCMU01 plasmid, which drives the previously defined pathway for tetrahydrofolate-mediated chloromethane dehalogenation. Comparison of complete genome sequences of strain CM4 and that of four other M. extorquens strains unable to grow with chloromethane showed that plasmid pCMU01 harbors unique genes without homologs in the compared genomes (bluB2, btuB, cobA, cbiD), as well as 13 duplicated genes with homologs of chromosome-borne genes involved in vitamin B12-associated biosynthesis and transport, or in tetrahydrofolate-dependent metabolism (folC2). In addition, the presence of both chromosomal and plasmid-borne genes for corrinoid salvaging pathways may ensure corrinoid coenzyme supply in challenging environments. Proteomes of M. extorquens CM4 grown with one-carbon substrates chloromethane and methanol were compared. Of the 49 proteins with differential abundance identified, only five (CmuA, CmuB, PurU, CobH2 and a PaaE-like uncharacterized putative oxidoreductase) are encoded by the pCMU01 plasmid. The mainly chromosome-encoded response to chloromethane involves gene clusters associated with oxidative stress, production of reducing equivalents (PntAA, Nuo complex), conversion of tetrahydrofolate-bound one-carbon units, and central metabolism. The mosaic organization of plasmid pCMU01 and the clustering of genes coding for dehalogenase enzymes and for biosynthesis of associated cofactors suggests a history of gene acquisition related to chloromethane utilization.
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Affiliation(s)
- Sandro Roselli
- Département Génétique Moléculaire, Génomique, Microbiologie, Université de Strasbourg, UMR7156, Centre national de la recherche scientifique, Strasbourg, France
| | - Thierry Nadalig
- Département Génétique Moléculaire, Génomique, Microbiologie, Université de Strasbourg, UMR7156, Centre national de la recherche scientifique, Strasbourg, France
| | - Stéphane Vuilleumier
- Département Génétique Moléculaire, Génomique, Microbiologie, Université de Strasbourg, UMR7156, Centre national de la recherche scientifique, Strasbourg, France
| | - Françoise Bringel
- Département Génétique Moléculaire, Génomique, Microbiologie, Université de Strasbourg, UMR7156, Centre national de la recherche scientifique, Strasbourg, France
- * E-mail:
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83
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Boutigny S, Saini A, Baidoo EEK, Yeung N, Keasling JD, Butland G. Physical and functional interactions of a monothiol glutaredoxin and an iron sulfur cluster carrier protein with the sulfur-donating radical S-adenosyl-L-methionine enzyme MiaB. J Biol Chem 2013; 288:14200-14211. [PMID: 23543739 DOI: 10.1074/jbc.m113.460360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The biosynthesis of iron sulfur (FeS) clusters, their trafficking from initial assembly on scaffold proteins via carrier proteins to final incorporation into FeS apoproteins, is a highly coordinated process enabled by multiprotein systems encoded in iscRSUAhscBAfdx and sufABCDSE operons in Escherichia coli. Although these systems are believed to encode all factors required for initial cluster assembly and transfer to FeS carrier proteins, accessory factors such as monothiol glutaredoxin, GrxD, and the FeS carrier protein NfuA are located outside of these defined systems. These factors have been suggested to function both as shuttle proteins acting to transfer clusters between scaffold and carrier proteins and in the final stages of FeS protein assembly by transferring clusters to client FeS apoproteins. Here we implicate both of these factors in client protein interactions. We demonstrate specific interactions between GrxD, NfuA, and the methylthiolase MiaB, a radical S-adenosyl-L-methionine-dependent enzyme involved in the maturation of a subset of tRNAs. We show that GrxD and NfuA physically interact with MiaB with affinities compatible with an in vivo function. We furthermore demonstrate that NfuA is able to transfer its cluster in vitro to MiaB, whereas GrxD is unable to do so. The relevance of these interactions was demonstrated by linking the activity of MiaB with GrxD and NfuA in vivo. We observe a severe defect in in vivo MiaB activity in cells lacking both GrxD and NfuA, suggesting that these proteins could play complementary roles in maturation and repair of MiaB.
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Affiliation(s)
- Sylvain Boutigny
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Avneesh Saini
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Edward E K Baidoo
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; Joint BioEnergy Institute, Emeryville, California 94608
| | - Natasha Yeung
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Jay D Keasling
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; Joint BioEnergy Institute, Emeryville, California 94608; Department of Chemical Engineering, University of California, Berkeley, California 94720; Department of Bioengineering, University of California, Berkeley, California 94720
| | - Gareth Butland
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
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84
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Santos AL, Gomes NC, Henriques I, Almeida A, Correia A, Cunha A. Role of Transition Metals in UV-B-Induced Damage to Bacteria. Photochem Photobiol 2013; 89:640-8. [DOI: 10.1111/php.12049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 01/16/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Ana L. Santos
- Dapartment of Biology & CESAM; University of Aveiro; Campus Universitário de Santiago; 3810-193; Aveiro; Portugal
| | - Newton C.M. Gomes
- Dapartment of Biology & CESAM; University of Aveiro; Campus Universitário de Santiago; 3810-193; Aveiro; Portugal
| | - Isabel Henriques
- Dapartment of Biology & CESAM; University of Aveiro; Campus Universitário de Santiago; 3810-193; Aveiro; Portugal
| | - Adelaide Almeida
- Dapartment of Biology & CESAM; University of Aveiro; Campus Universitário de Santiago; 3810-193; Aveiro; Portugal
| | - António Correia
- Dapartment of Biology & CESAM; University of Aveiro; Campus Universitário de Santiago; 3810-193; Aveiro; Portugal
| | - Angela Cunha
- Dapartment of Biology & CESAM; University of Aveiro; Campus Universitário de Santiago; 3810-193; Aveiro; Portugal
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85
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Roche B, Aussel L, Ezraty B, Mandin P, Py B, Barras F. Iron/sulfur proteins biogenesis in prokaryotes: formation, regulation and diversity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:455-69. [PMID: 23298813 DOI: 10.1016/j.bbabio.2012.12.010] [Citation(s) in RCA: 212] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/21/2012] [Accepted: 12/27/2012] [Indexed: 12/17/2022]
Abstract
Iron/sulfur centers are key cofactors of proteins intervening in multiple conserved cellular processes, such as gene expression, DNA repair, RNA modification, central metabolism and respiration. Mechanisms allowing Fe/S centers to be assembled, and inserted into polypeptides have attracted much attention in the last decade, both in eukaryotes and prokaryotes. Basic principles and recent advances in our understanding of the prokaryotic Fe/S biogenesis ISC and SUF systems are reviewed in the present communication. Most studies covered stem from investigations in Escherichia coli and Azotobacter vinelandii. Remarkable insights were brought about by complementary structural, spectroscopic, biochemical and genetic studies. Highlights of the recent years include scaffold mediated assembly of Fe/S cluster, A-type carriers mediated delivery of clusters and regulatory control of Fe/S homeostasis via a set of interconnected genetic regulatory circuits. Also, the importance of Fe/S biosynthesis systems in mediating soft metal toxicity was documented. A brief account of the Fe/S biosynthesis systems diversity as present in current databases is given here. Moreover, Fe/S biosynthesis factors have themselves been the object of molecular tailoring during evolution and some examples are discussed here. An effort was made to provide, based on the E. coli system, a general classification associating a given domain with a given function such as to help next search and annotation of genomes. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
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Affiliation(s)
- Béatrice Roche
- Institut de Microbiologie de la Méditerranée, Marseille, France
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86
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Sánchez-Riego AM, López-Maury L, Florencio FJ. Glutaredoxins are essential for stress adaptation in the cyanobacterium Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2013; 4:428. [PMID: 24204369 PMCID: PMC3816324 DOI: 10.3389/fpls.2013.00428] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/10/2013] [Indexed: 05/10/2023]
Abstract
Glutaredoxins are small redox proteins able to reduce disulfides and mixed disulfides between GSH and proteins. Synechocystis sp. PCC 6803 contains three genes coding for glutaredoxins: ssr2061 (grxA) and slr1562 (grxB) code for dithiolic glutaredoxins while slr1846 (grxC) codes for a monothiolic glutaredoxin. We have analyzed the expression of these glutaredoxins in response to different stresses, such as high light, H2O2 and heat shock. Analysis of the mRNA levels showed that grxA is only induced by heat while grxC is repressed by heat shock and is induced by high light and H2O2. In contrast, grxB expression was maintained almost constant under all conditions. Analysis of GrxA and GrxC protein levels by western blot showed that GrxA increases in response to high light, heat or H2O2 while GrxC is only induced by high light and H2O2, in accordance with its mRNA levels. In addition, we have also generated mutants that have interrupted one, two, or three glutaredoxin genes. These mutants were viable and did not show any different phenotype from the WT under standard growth conditions. Nevertheless, analysis of these mutants under several stress conditions revealed that single grxA mutants grow slower after H2O2, heat and high light treatments, while mutants in grxB are indistinguishable from WT. grxC mutants were hypersensitive to treatments with H2O2, heat, high light and metals. A double grxAgrxC mutant was found to be even more sensitive to H2O2 than each corresponding single mutants. Surprisingly a mutation in grxB suppressed totally or partially the phenotypes of grxA and grxC mutants except the H2O2 sensitivity of the grxC mutant. This suggests that grxA and grxC participate in independent pathways while grxA and grxB participate in a common pathway for H2O2 resistance. The data presented here show that glutaredoxins are essential for stress adaptation in cyanobacteria, although their targets and mechanism of action remain unidentified.
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Affiliation(s)
| | | | - Francisco J. Florencio
- *Correspondence: Francisco J. Florencio, Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Av Americo Vespucio 49, E 41092 Seville, Spain e-mail:
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87
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Crack JC, Green J, Hutchings MI, Thomson AJ, Le Brun NE. Bacterial iron-sulfur regulatory proteins as biological sensor-switches. Antioxid Redox Signal 2012; 17:1215-31. [PMID: 22239203 PMCID: PMC3430481 DOI: 10.1089/ars.2012.4511] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SIGNIFICANCE In recent years, bacterial iron-sulfur cluster proteins that function as regulators of gene transcription have emerged as a major new group. In all cases, the cluster acts as a sensor of the environment and enables the organism to adapt to the prevailing conditions. This can range from mounting a response to oxidative or nitrosative stress to switching between anaerobic and aerobic respiratory pathways. The sensitivity of these ancient cofactors to small molecule reactive oxygen and nitrogen species, in particular, makes them ideally suited to function as sensors. RECENT ADVANCES An important challenge is to obtain mechanistic and structural information about how these regulators function and, in particular, how the chemistry occurring at the cluster drives the subsequent regulatory response. For several regulators, including FNR, SoxR, NsrR, IscR, and Wbl proteins, major advances in understanding have been gained recently and these are reviewed here. CRITICAL ISSUES A common theme emerging from these studies is that the sensitivity and specificity of the cluster of each regulatory protein must be exquisitely controlled by the protein environment of the cluster. FUTURE DIRECTIONS A major future challenge is to determine, for a range of regulators, the key factors for achieving control of sensitivity/specificity. Such information will lead, eventually, to a system understanding of stress response, which often involves more than one regulator.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom
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88
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Kamnev AA, Tugarova AV, Kovács K, Kuzmann E, Biró B, Tarantilis PA, Homonnay Z. Emission (57Co) Mössbauer spectroscopy as a tool for probing speciation and metabolic transformations of cobalt(II) in bacterial cells. Anal Bioanal Chem 2012; 405:1921-7. [DOI: 10.1007/s00216-012-6370-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/18/2012] [Accepted: 08/20/2012] [Indexed: 11/25/2022]
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89
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Palmer T, Berks BC. The twin-arginine translocation (Tat) protein export pathway. Nat Rev Microbiol 2012; 10:483-96. [PMID: 22683878 DOI: 10.1038/nrmicro2814] [Citation(s) in RCA: 359] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The twin-arginine translocation (Tat) protein export system is present in the cytoplasmic membranes of most bacteria and archaea and has the highly unusual property of transporting fully folded proteins. The system must therefore provide a transmembrane pathway that is large enough to allow the passage of structured macromolecular substrates of different sizes but that maintains the impermeability of the membrane to ions. In the Gram-negative bacterium Escherichia coli, this complex task can be achieved by using only three small membrane proteins: TatA, TatB and TatC. In this Review, we summarize recent advances in our understanding of how this remarkable machine operates.
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Affiliation(s)
- Tracy Palmer
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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90
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Raimunda D, Long JE, Sassetti CM, Argüello JM. Role in metal homeostasis of CtpD, a Co²⁺ transporting P(1B4)-ATPase of Mycobacterium smegmatis. Mol Microbiol 2012; 84:1139-49. [PMID: 22591178 DOI: 10.1111/j.1365-2958.2012.08082.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Genetic studies in the tuberculosis mouse model have suggested that mycobacterial metal efflux systems, such as the P(1B4)-ATPase CtpD, are important for pathogenesis. The specificity for substrate metals largely determines the function of these ATPases; however, various substrates have been reported for bacterial and plant P(1B4)-ATPases leaving their function uncertain. Here we describe the functional role of the CtpD protein of Mycobacterium smegmatis. An M. smegmatis mutant strain lacking the ctpD gene was hypersensitive to Co²⁺ and Ni²⁺ and accumulated these metals in the cytoplasm. ctpD transcription was induced by both Co²⁺ and superoxide stress. Biochemical characterization of heterologously expressed, affinity-purified CtpD showed that this ATPase is activated by Co²⁺, Ni²⁺ and to a lesser extend Zn²⁺ (20% of maximum activity). The protein was also able to bind one Co²⁺, Ni²⁺ or Zn²⁺ to its transmembrane transport site. These observations indicate that CtpD is important for Co²⁺ and Ni²⁺ homeostasis in M. smegmatis, and that M. tuberculosis CtpD orthologue could be involved in metal detoxification and resisting cellular oxidative stress by modulating the intracellular concentration of these metals.
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Affiliation(s)
- Daniel Raimunda
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, USA
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91
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Crack JC, Green J, Thomson AJ, Le Brun NE. Iron-sulfur cluster sensor-regulators. Curr Opin Chem Biol 2012; 16:35-44. [PMID: 22387135 DOI: 10.1016/j.cbpa.2012.02.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 01/13/2012] [Accepted: 02/08/2012] [Indexed: 10/28/2022]
Abstract
Regulatory proteins that contain an iron-sulfur cluster cofactor constitute a group that is growing both in number and importance, with a range of functions that include sensing of molecular oxygen, stress response, and iron regulation. In all cases, the cluster plays a central role, as a sensory module, in controlling the activity of the regulator. In some cases, the cluster is required for the protein to attain its regulatory form, while in others the active form requires loss or modification of the cluster. In this way, nature has exploited the inherent reactivity of iron-sulfur clusters. Here, we focus on recent advances that provide new insight into the remarkable chemistries exhibited by these regulators, and how they achieve the required levels of sensitivity and specificity.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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92
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93
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Hatamie S, Nouri M, Karandikar S, Kulkarni A, Dhole S, Phase D, Kale S. Complexes of cobalt nanoparticles and polyfunctional curcumin as antimicrobial agents. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2012. [DOI: 10.1016/j.msec.2011.10.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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94
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Zhuang W, Yuan D, Li JR, Luo Z, Zhou HC, Bashir S, Liu J. Highly potent bactericidal activity of porous metal-organic frameworks. Adv Healthc Mater 2012. [PMID: 23184726 DOI: 10.1002/adhm.201100043] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Recent outbreaks of bacterial infection leading to human fatalities have been a motivational force for us to develop antibacterial agents with high potency and long-term stability. A novel cobalt (Co) based metal-organic framework (MOF) was tested and shown to be highly effective at inactivating model microorganisms. Gram-negative bacteria, Escherichia coli (strains DH5alpha and XL1-Blue) were selected to determine the antibacterial activities of the Co MOF. In this MOF, the Co serves as a central element and an octa-topic carboxylate ligand, tetrakis [(3,5-dicarboxyphenyl)-oxamethyl] methane (TDM(8-) ) serves as a bridging linker. X-ray crystallographic studies indicate that Co-TDM crystallizes in tetragonal space group P$\overline 4$2(1) m with a porous 3D framework. The potency of the Co-TDM disinfectant was evaluated using a minimal bactericidal concentration (MBC) benchmark and was determined to be 10-15 ppm within a short incubation time period (<60 min). Compared with previous work using silver nanoparticles and silver-modified TiO(2) nano- composites over the same time period, the MBC and effectiveness of Co-TDM are superior. Electron microscopy images indicate that the Co-TDM displayed distinctive grain boundaries and well-developed reticulates. The Co active sites rapidly catalyzed the lipid peroxidation, causing rupture of the bacterial membrane followed by inactivation, with 100% recycling and high persistence (>4 weeks). This MOF-based approach may lead to a new paradigm for MOF applications in diverse biological fields due to their inherent porous structure, tunable surface functional groups, and adjustable metal coordination environments.
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Affiliation(s)
- Wenjuan Zhuang
- Chemistry Department, Texas A&M University, College Station, TX 77843, USA
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95
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Abstract
In Escherichia coli, the corA gene encodes a transporter that mediates the influx of Co(2+), Mg(2+), and Ni(2+) into the cell. During the course of experiments aimed at identifying RNase III-dependent genes in E. coli, we observed that steady-state levels of corA mRNA as well as the degree of cobalt influx into the cell were dependent on cellular concentrations of RNase III. In addition, changes in corA expression levels by different cellular concentrations of RNase III were closely correlated with degrees of resistance of E. coli cells to Co(2+) and Ni(2+). In vitro and in vivo cleavage analyses of corA mRNA identified RNase III cleavage sites in the 5'-untranslated region of the corA mRNA. The introduction of nucleotide substitutions at the identified RNase III cleavage sites abolished RNase III cleavage activity on corA mRNA and resulted in prolonged half-lives of the mRNA, which demonstrates that RNase III cleavage constitutes a rate-determining step for corA mRNA degradation. These findings reveal an RNase III-mediated regulatory pathway that functions to modulate corA expression and, in turn, the influx of metal ions transported by CorA in E. coli.
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96
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Silver(I), mercury(II), cadmium(II), and zinc(II) target exposed enzymic iron-sulfur clusters when they toxify Escherichia coli. Appl Environ Microbiol 2012; 78:3614-21. [PMID: 22344668 DOI: 10.1128/aem.07368-11] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The toxicity of soft metals is of broad interest to microbiologists, both because such metals influence the community structures in natural environments and because several metals are used as antimicrobial agents. Their potency roughly parallels their thiophilicity, suggesting that their primary biological targets are likely to be enzymes that contain key sulfhydryl moieties. A recent study determined that copper poisons Escherichia coli in part by attacking the exposed [4Fe-4S] clusters of dehydratases. The present investigation sought to test whether other soft metals also target these enzymes. In vitro experiments revealed that low-micromolar concentrations of Ag(I) and Hg(II) directly inactivated purified fumarase A, a member of the dehydratase family. The enzyme was also poisoned by higher levels of Cd(II) and Zn(II), but it was unaffected by even millimolar concentrations of Mn(II), Co(II), Ni(II), and Pb(II). Electron paramagnetic resonance analysis and measurements of released iron confirmed that damage was associated with destruction of the [4Fe-4S] cluster, and indeed, the reconstruction of the cluster fully restored activity. Growth studies were then performed to test whether dehydratase damage might underlie toxicity in vivo. Barely toxic doses of Ag(I), Hg(II), Cd(II), and Zn(II) inactivated all tested members of the [4Fe-4S] dehydratase family. Again, activity was recovered when the clusters were rebuilt. The metals did not diminish the activities of other sampled enzymes, including NADH dehydrogenase I, an iron-sulfur protein whose clusters are shielded by polypeptide. Thus, the data indicate that dehydratases are damaged by the concentrations of metals that initiate bacteriostasis.
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97
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Rancelis V, Cesniene T, Kleizaite V, Zvingila D, Balciuniene L. Influence of cobalt uptake by Vicia faba seeds on chlorophyll morphosis induction, SOD polymorphism, and DNA methylation. ENVIRONMENTAL TOXICOLOGY 2012; 27:32-41. [PMID: 20549638 DOI: 10.1002/tox.20609] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 03/02/2010] [Accepted: 03/13/2010] [Indexed: 05/29/2023]
Abstract
Vicia faba plants show polymorphism to cobalt (Co) excess, expressed by a different degree of chlorophyll morphosis (CM)-from normally green (N) to yellow (Y) seedlings. For superoxide dismutase (SOD), the high V. faba polymorphism was revealed and increased by Co stress. Epigenetic mechanisms may be involved in both phenomena. For such reasons, we investigated the effect of 5-azacytosine (AzaC) and Na butyrate (NaBut) on CM induction, SOD polymorphism, and DNA methylation-demethylation events in Co(NO(3) )(2) affected plants, without or with AzaC or NaBut. CMs were induced after treatment of seeds for 8 h with 7.5 mM Co(NO(3) )(2) plus 12 h with H(2) O or 8 h with H(2) O plus 12 h with Co(NO(3) )(2) . In the same order AzaC and NaBut were applied in concentrations equimolar to Co(NO(3) )(2) . SOD isoforms were investigated electrophoretically, and for DNA methylation-demethylation events the Aina [Aina et al. (2004) Physiol Plant 121:472-480] system was applied upon using the random amplified polymorphic DNA (RAPD) method employing restrictases MspI and HpaII. The effect of AzaC and NaBut on CM induction in combination with Co was unclear. Posttreatment with Co was more effective than Co-pretreatment. SOD polymorphism was significantly strengthened by NaBut. Detection of DNA methylation-demethylation events depended on the primers used for RAPD analysis. With AP5 and MP4 primers, DNA demethylation was observed in N-seedlings after exposure to Co, AzaC or NaBut applied separately. With primer A6, only DNA methylation events were determined in N-seedlings from seeds exposed to Co or Co-AzaC, and in Y-seedlings after Co-AzaC or Co-NaBut treatment. UPGMA grouping of the results showed that all N-seedlings comprised one common cluster after Co exposure, independently of treatment combinations (Co alone, Co with AzaC, Co with NaBut). On the contrary, no significant differences were determined in SOD polymorphism among the most resistant N-seedlings and the most severely affected Y-seedlings.
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Affiliation(s)
- Vytautas Rancelis
- Department of Botany and Genetics, Vilnius University, Vilnius, Lithuania
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Analysis of hypoxia and hypoxia-like states through metabolite profiling. PLoS One 2011; 6:e24741. [PMID: 21931840 PMCID: PMC3171472 DOI: 10.1371/journal.pone.0024741] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 08/16/2011] [Indexed: 01/02/2023] Open
Abstract
Background In diverse organisms, adaptation to low oxygen (hypoxia) is mediated through complex gene expression changes that can, in part, be mimicked by exposure to metals such as cobalt. Although much is known about the transcriptional response to hypoxia and cobalt, little is known about the all-important cell metabolism effects that trigger these responses. Methods and Findings Herein we use a low molecular weight metabolome profiling approach to identify classes of metabolites in yeast cells that are altered as a consequence of hypoxia or cobalt exposures. Key findings on metabolites were followed-up by measuring expression of relevant proteins and enzyme activities. We find that both hypoxia and cobalt result in a loss of essential sterols and unsaturated fatty acids, but the basis for these changes are disparate. While hypoxia can affect a variety of enzymatic steps requiring oxygen and heme, cobalt specifically interferes with diiron-oxo enzymatic steps for sterol synthesis and fatty acid desaturation. In addition to diiron-oxo enzymes, cobalt but not hypoxia results in loss of labile 4Fe-4S dehydratases in the mitochondria, but has no effect on homologous 4Fe-4S dehydratases in the cytosol. Most striking, hypoxia but not cobalt affected cellular pools of amino acids. Amino acids such as aromatics were elevated whereas leucine and methionine, essential to the strain used here, dramatically decreased due to hypoxia induced down-regulation of amino acid permeases. Conclusions These studies underscore the notion that cobalt targets a specific class of iron proteins and provide the first evidence for hypoxia effects on amino acid regulation. This research illustrates the power of metabolite profiling for uncovering new adaptations to environmental stress.
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Abstract
Cobalt is an essential trace element in both prokaryotes and eukaryotes. Nevertheless, it occurs less frequently in metalloproteins than other transition metals. This low occurrence appears to be due to the metal's low abundance in nature as well as its competition with iron, whose biologically critical functions include respiration and photosynthesis. In this review, we discuss the biological role of cobalt, the major effects of cobalt on iron utilization, as well as several mechanisms that cells have developed to circumvent the toxicity of cobalt while still exploiting its chemistry.
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Affiliation(s)
- Sachi Okamoto
- University of British Columbia - Microbiology and Immunology, Vancouver, British Columbia, Canada
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