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Muñoz-Diaz P, Jiménez K, Luraschi R, Cornejo F, Figueroa M, Vera C, Rivas-Pardo A, Sandoval JM, Vásquez C, Arenas F. Anaerobic RSH-dependent tellurite reduction contributes to Escherichia coli tolerance against tellurite. Biol Res 2022; 55:13. [PMID: 35313991 PMCID: PMC8935827 DOI: 10.1186/s40659-022-00383-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 03/07/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tellurium is a rare metalloid that exerts high toxicity on cells, especially on bacteria, partly due to reactive oxygen species (ROS) generation. Moreover, it has also been observed that tellurite can target free cell thiols groups (RSH) (i.e. reduced glutathione (GSH)), enhancing the cellular redox imbalance. Additionally, in vitro experiments have suggested that several enzymes can reduce tellurite (IV) to its elemental form (0); where RSH present on their active sites may be responsible for the process. Nevertheless, the mechanisms implemented by bacteria for tellurite reduction and its role in resistance have not been evaluated in vivo. RESULTS This work shows that tellurite reduction to elemental tellurium is increased under anaerobic conditions in E. coli cells. The in vivo tellurite reduction is related to the intracellular concentration of total RSH, in the presence and absence of oxygen. This metabolization of tellurite directly contributes to the resistance of the bacteria to the oxyanion. CONCLUSIONS We demonstrated that in vivo tellurite reduction is related to the intracellular thiol concentration, i.e. large availability of cellular RSH groups, results in a more significant reduction of tellurite. Furthermore, we observed that, when the bacterium exhibits less resistance to the oxyanion, a decreased tellurite reduction was seen, affecting the growth fitness. Together, these results let us propose that tellurite reduction and the intracellular RSH content are related to the oxyanion bacterial resistance, this tripartite mechanism in an oxygen-independent anaerobic process.
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Affiliation(s)
- P Muñoz-Diaz
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - K Jiménez
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - R Luraschi
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - F Cornejo
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - M Figueroa
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - C Vera
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - A Rivas-Pardo
- Laboratorio de Genómica Microbiana, Centro de Genómica Y Bioinformática, Universidad Mayor, Santiago, Chile
| | - J M Sandoval
- Facultad de Ciencias, Universidad Arturo Prat, Iquique, Chile
| | - C Vásquez
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - F Arenas
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química Y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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2
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Figueroa M, Fernandez V, Arenas-Salinas M, Ahumada D, Muñoz-Villagrán C, Cornejo F, Vargas E, Latorre M, Morales E, Vásquez C, Arenas F. Synthesis and Antibacterial Activity of Metal(loid) Nanostructures by Environmental Multi-Metal(loid) Resistant Bacteria and Metal(loid)-Reducing Flavoproteins. Front Microbiol 2018; 9:959. [PMID: 29869640 PMCID: PMC5962736 DOI: 10.3389/fmicb.2018.00959] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 04/24/2018] [Indexed: 12/13/2022] Open
Abstract
Microbes are suitable candidates to recover and decontaminate different environments from soluble metal ions, either via reduction or precipitation to generate insoluble, non-toxic derivatives. In general, microorganisms reduce toxic metal ions generating nanostructures (NS), which display great applicability in biotechnological processes. Since the molecular bases of bacterial reduction are still unknown, the search for new -environmentally safe and less expensive- methods to synthesize NS have made biological systems attractive candidates. Here, 47 microorganisms isolated from a number of environmental samples were analyzed for their tolerance or sensitivity to 19 metal(loid)s. Ten of them were highly tolerant to some of them and were assessed for their ability to reduce these toxicants in vitro. All isolates were analyzed by 16S rRNA gene sequencing, fatty acids composition, biochemical tests and electron microscopy. Results showed that they belong to the Enterobacter, Staphylococcus, Acinetobacter, and Exiguobacterium genera. Most strains displayed metal(loid)-reducing activity using either NADH or NADPH as cofactor. While Acinetobacter schindleri showed the highest tellurite ( TeO32- ) and tetrachloro aurate ( AuCl4- ) reducing activity, Staphylococcus sciuri and Exiguobacterium acetylicum exhibited selenite ( SeO32- ) and silver (Ag+) reducing activity, respectively. Based on these results, we used these bacteria to synthetize, in vivo and in vitro Te, Se, Au, and Ag-containing nanostructures. On the other hand, we also used purified E. cloacae glutathione reductase to synthesize in vitro Te-, Ag-, and Se-containing NS, whose morphology, size, composition, and chemical composition were evaluated. Finally, we assessed the putative anti-bacterial activity exhibited by the in vitro synthesized NS: Te-containing NS were more effective than Au-NS in inhibiting Escherichia coli and Listeria monocytogenes growth. Aerobically synthesized TeNS using MF09 crude extracts showed MICs of 45- and 66- μg/ml for E. coli and L. monocytogenes, respectively. Similar MIC values (40 and 82 μg/ml, respectively) were observed for TeNS generated using crude extracts from gorA-overexpressing E. coli. In turn, AuNS MICs for E. coli and L. monocytogenes were 64- and 68- μg/ml, respectively.
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Affiliation(s)
- Maximiliano Figueroa
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Valentina Fernandez
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | | | - Diego Ahumada
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Claudia Muñoz-Villagrán
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.,Departamento de Ciencias Básicas, Facultad de Ciencia, Universidad Santo Tomas, Sede Santiago, Chile
| | - Fabián Cornejo
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Esteban Vargas
- Center for the Development of Nanoscience and Nanotechnology, Santiago, Chile
| | - Mauricio Latorre
- Mathomics, Centro de Modelamiento Matemático, Universidad de Chile, Beauchef, Santiago, Chile.,Fondap-Center of Genome Regulation, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.,Laboratorio de Bioinformática y Expresión Génica, INTA, Universidad de Chile, Santiago, Chile.,Instituto de Ciencias de la Ingeniería, Universidad de O'Higgins, Rancagua, Chile
| | | | - Claudio Vásquez
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Felipe Arenas
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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3
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Ambrus A, Adam-Vizi V. Human dihydrolipoamide dehydrogenase (E3) deficiency: Novel insights into the structural basis and molecular pathomechanism. Neurochem Int 2017; 117:5-14. [PMID: 28579060 DOI: 10.1016/j.neuint.2017.05.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/22/2017] [Accepted: 05/30/2017] [Indexed: 11/18/2022]
Abstract
This review summarizes our present view on the molecular pathogenesis of human (h) E3-deficiency caused by a variety of genetic alterations with a special emphasis on the moonlighting biochemical phenomena related to the affected (dihydro)lipoamide dehydrogenase (LADH, E3, gene: dld), in particular the generation of reactive oxygen species (ROS). E3-deficiency is a rare autosomal recessive genetic disorder frequently presenting with a neonatal onset and premature death; the highest carrier rate of a single pathogenic dld mutation (1:94-1:110) was found among Ashkenazi Jews. Patients usually die during acute episodes that generally involve severe metabolic decompensation and lactic acidosis leading to neurological, cardiological, and/or hepatological manifestations. The disease owes its severity to the fact that LADH is the common E3 subunit of the alpha-ketoglutarate (KGDHc), pyruvate (PDHc), and branched-chain α-keto acid dehydrogenase complexes and is also part of the glycine cleavage system, hence the malfunctioning of LADH simultaneously incapacitates several central metabolic pathways. Nevertheless, the clinical pictures are usually not unequivocally portrayed through the loss of LADH activities and imply auxiliary mechanisms that exacerbate the symptoms and outcomes of this disorder. Enhanced ROS generation by disease-causing hE3 variants as well as by the E1-E2 subcomplex of the hKGDHc likely contributes to selected pathogeneses of E3-deficiency, which could be targeted by specific drugs or antioxidants; lipoic acid was demonstrated to be a potent inhibitor of ROS generation by hE3 in vitro. Flavin supplementation might prove to be beneficial for those mutations triggering FAD loss in the hE3 component. Selected pathogenic hE3 variants lose their affinity for the E2 component of the hPDHc, a mechanism which warrants scrutiny also for other E3-haboring complexes.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary.
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary.
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4
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Ambrus A, Nemeria NS, Torocsik B, Tretter L, Nilsson M, Jordan F, Adam-Vizi V. Formation of reactive oxygen species by human and bacterial pyruvate and 2-oxoglutarate dehydrogenase multienzyme complexes reconstituted from recombinant components. Free Radic Biol Med 2015; 89:642-50. [PMID: 26456061 PMCID: PMC4684775 DOI: 10.1016/j.freeradbiomed.2015.10.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 09/18/2015] [Accepted: 10/03/2015] [Indexed: 01/25/2023]
Abstract
Individual recombinant components of pyruvate and 2-oxoglutarate dehydrogenase multienzyme complexes (PDHc, OGDHc) of human and Escherichia coli (E. coli) origin were expressed and purified from E. coli with optimized protocols. The four multienzyme complexes were each reconstituted under optimal conditions at different stoichiometric ratios. Binding stoichiometries for the highest catalytic efficiency were determined from the rate of NADH generation by the complexes at physiological pH. Since some of these complexes were shown to possess 'moonlighting' activities under pathological conditions often accompanied by acidosis, activities were also determined at pH 6.3. As reactive oxygen species (ROS) generation by the E3 component of hOGDHc is a pathologically relevant feature, superoxide generation by the complexes with optimal stoichiometry was measured by the acetylated cytochrome c reduction method in both the forward and the reverse catalytic directions. Various known affectors of physiological activity and ROS production, including Ca(2+), ADP, lipoylation status or pH, were investigated. The human complexes were also reconstituted with the most prevalent human pathological mutant of the E3 component, G194C and characterized; isolated human E3 with the G194C substitution was previously reported to have an enhanced ROS generating capacity. It is demonstrated that: i. PDHc, similarly to OGDHc, is able to generate ROS and this feature is displayed by both the E. coli and human complexes, ii. Reconstituted hPDHc generates ROS at a significantly higher rate as compared to hOGDHc in both the forward and the reverse reactions when ROS generation is calculated for unit mass of their common E3 component, iii. The E1 component or E1-E2 subcomplex generates significant amount of ROS only in hOGDHc; iv. Incorporation of the G194C variant of hE3, the result of a disease-causing mutation, into reconstituted hOGDHc and hPDHc indeed leads to a decreased activity of both complexes and higher ROS generation by only hOGDHc and only in its reverse reaction.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Natalia S Nemeria
- Department of Chemistry, Rutgers, the State University, Newark, NJ 07102, USA
| | - Beata Torocsik
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Laszlo Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Mattias Nilsson
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Frank Jordan
- Department of Chemistry, Rutgers, the State University, Newark, NJ 07102, USA
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary.
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5
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Sakamoto A, Terui Y, Yoshida T, Yamamoto T, Suzuki H, Yamamoto K, Ishihama A, Igarashi K, Kashiwagi K. Three members of polyamine modulon under oxidative stress conditions: two transcription factors (SoxR and EmrR) and a glutathione synthetic enzyme (GshA). PLoS One 2015; 10:e0124883. [PMID: 25898225 PMCID: PMC4405209 DOI: 10.1371/journal.pone.0124883] [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: 02/10/2015] [Accepted: 03/18/2015] [Indexed: 02/05/2023] Open
Abstract
Members of polyamine modulon whose synthesis is enhanced at the level of translation were looked for under oxidative stress conditions caused by 0.6 μM K2TeO3. When an Escherichia coli polyamine-requiring mutant MA261 was cultured in the presence of K2TeO3, the degree of polyamine stimulation of cell growth was greater than in cells cultured in the absence of K2TeO3. Under these conditions, synthesis of SoxR, a transcriptional factor for expression of the superoxide response regulon, EmrR, a negative transcriptional factor for expression of the genes for drug excretion proteins, EmrA and EmrB, and of GshA, γ-glutamylcysteine synthetase necessary for glutathione (GSH) synthesis, were stimulated by polyamines at the level of translation. Polyamine stimulation of SoxR and EmrR synthesis was dependent on the existence of an unusually located Shine-Dalgarno (SD) sequence in soxR and emrR mRNAs. Polyamine stimulation of GshA synthesis was due to the existence of the inefficient initiation codon UUG instead of AUG. Polyamine stimulation of the synthesis of EmrR was mainly observed at the logarithmic phase of growth, while that of the synthesis of SoxR and GshA was at the stationary phase. These results strongly suggest that polyamines are involved in easing of oxidative stress through stimulation of synthesis of SoxR, EmrR and GshA together with RpoS, previously found as a member of polyamine modulon at the stationary phase.
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Affiliation(s)
- Akihiko Sakamoto
- Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba, Japan
| | - Yusuke Terui
- Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba, Japan
| | - Taketo Yoshida
- Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba, Japan
| | - Taku Yamamoto
- Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba, Japan
| | - Hideyuki Suzuki
- Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto, Kyoto, Japan
| | - Kaneyoshi Yamamoto
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
| | - Akira Ishihama
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
| | - Kazuei Igarashi
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Chiba, Japan
- Amine Pharma Research Institute, Innovation Plaza at Chiba University, Chiba, Chiba, Japan
| | - Keiko Kashiwagi
- Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba, Japan
- * E-mail:
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6
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Tellurite-mediated damage to the Escherichia coli NDH-dehydrogenases and terminal oxidases in aerobic conditions. Arch Biochem Biophys 2015; 566:67-75. [DOI: 10.1016/j.abb.2014.10.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 09/27/2014] [Accepted: 10/19/2014] [Indexed: 11/20/2022]
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7
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Global transcriptomic analysis uncovers a switch to anaerobic metabolism in tellurite-exposed Escherichia coli. Res Microbiol 2014; 165:566-70. [DOI: 10.1016/j.resmic.2014.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 06/30/2014] [Accepted: 07/03/2014] [Indexed: 11/20/2022]
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8
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Arenas FA, Leal CA, Pinto CA, Arenas-Salinas MA, Morales WA, Cornejo FA, Díaz-Vásquez WA, Vásquez CC. On the mechanism underlying tellurite reduction by Aeromonas caviae ST dihydrolipoamide dehydrogenase. Biochimie 2014; 102:174-82. [PMID: 24680738 DOI: 10.1016/j.biochi.2014.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/17/2014] [Indexed: 10/25/2022]
Abstract
The dihydrolipoamide dehydrogenase (LpdA) from the tellurite-resistant bacterium Aeromonas caviae ST reduces tellurite to elemental tellurium. To characterize this NADH-dependent activity, the A. caviae lpdA gene was subjected to site-directed mutagenesis and genes containing C45A, H322Y and E354K substitutions were individually transformed into Escherichia coli Δlpd. Cells expressing the modified genes exhibited decreased pyruvate dehydrogenase, dihydrolipoamide dehydrogenase and TR activity regarding that observed with the wild type A. caviae lpdA gene. In addition, cells expressing the altered lpdA genes showed increased oxidative stress levels and tellurite sensitivity than those carrying the wild type counterpart. The involvement of Cys residues in LpdA's TR activity was analyzed using specific inhibitors that interact with catalytic cysteines and/or disulfide bridges such as aurothiomalate, zinc or nickel. TR activity of purified LpdA was drastically affected by these compounds. Since LpdA belongs to the flavoprotein family, the involvement of the FAD/NAD(P)(+)-binding domain in TR activity was determined. FAD removal from purified LpdA results in loss of TR activity, which was restored with exogenously added FAD. Substitutions in E354, involved in FAD/NADH binding, resulted in low TR activity because of flavin loss. Finally, changing H322 (involved in NAD(+)/NADH binding) by tyrosine also resulted in altered TR activity.
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Affiliation(s)
- F A Arenas
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - C A Leal
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - C A Pinto
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - M A Arenas-Salinas
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile
| | - W A Morales
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile
| | - F A Cornejo
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - W A Díaz-Vásquez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile; Facultad de Ciencia, Universidad San Sebastián, Santiago, Chile
| | - C C Vásquez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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9
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Tellurite reduction by Escherichia coli NDH-II dehydrogenase results in superoxide production in membranes of toxicant-exposed cells. Biometals 2014; 27:237-46. [DOI: 10.1007/s10534-013-9701-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 12/29/2013] [Indexed: 02/05/2023]
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10
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Monounsaturated fatty acids are substrates for aldehyde generation in tellurite-exposed Escherichia coli. BIOMED RESEARCH INTERNATIONAL 2013; 2013:563756. [PMID: 23991420 PMCID: PMC3749545 DOI: 10.1155/2013/563756] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/09/2013] [Indexed: 11/17/2022]
Abstract
Reactive oxygen species (ROS) damage macromolecules and cellular components in nearly all kinds of cells and often generate toxic intracellular byproducts. In this work, aldehyde generation derived from the Escherichia coli membrane oxidation as well as membrane fatty acid profiles, protein oxidation, and bacterial resistance to oxidative stress elicitors was evaluated. Studies included wild-type cells as well as cells exhibiting a modulated monounsaturated fatty acid (MUFA) ratio. The hydroxyaldehyde 4-hydroxy 2-nonenal was found to be most likely produced by E. coli, whose levels are dependent upon exposure to oxidative stress elicitors. Aldehyde amounts and markers of oxidative damage decreased upon exposure to E. coli containing low MUFA ratios, which was paralleled by a concomitant increase in resistance to ROS-generating compounds. MUFAs ratio, lipid peroxidation, and aldehyde generation were found to be directly related; that is, the lower the MUFAs ratio, the lower the peroxide and aldehyde generation levels. These results provide additional evidence about MUFAs being targets for membrane lipid oxidation and their relevance in aldehyde generation.
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11
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Valdivia-González M, Pérez-Donoso JM, Vásquez CC. Effect of tellurite-mediated oxidative stress on the Escherichia coli glycolytic pathway. Biometals 2012; 25:451-8. [PMID: 22234496 DOI: 10.1007/s10534-012-9518-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 12/29/2011] [Indexed: 11/24/2022]
Abstract
To unveil the metabolic impact of tellurite in the bacterial cell, the effect of this toxicant on the expression and activity of key enzymes of the Escherichia coli glycolytic pathway was analyzed. E. coli exposure to tellurite results in: (i) increased glucose consumption, which was paralleled by an increased expression of the glucose transporter-encoding gene ptsG, (ii) augmented phosphoglucoisomerase activity and pgi transcription, (iii) decreased activity of the enzymatic regulators phosphofructokinase and pyruvate kinase. In spite of these observations, increased intracellular pyruvate, phosphoenol pyruvate and phosphorylated sugars was observed. E. coli lacking key glycolytic enzymes was considerably more sensitive to tellurite than the parental, isogenic, wild type strain. Taken together, these results suggest that increasing the availability of key metabolites (pyruvate, phosphoenol pyruvate, NADPH), required to respond to tellurite mediated-stress, E. coli shifts the carbon flux towards the pentose phosphate pathway thus facilitating the functioning of the Entner-Doudoroff pathway and/or the glycolytic productive phase.
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Affiliation(s)
- Mauricio Valdivia-González
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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12
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Sandoval JM, Arenas FA, Vásquez CC. Glucose-6-phosphate dehydrogenase protects Escherichia coli from tellurite-mediated oxidative stress. PLoS One 2011; 6:e25573. [PMID: 21984934 PMCID: PMC3184162 DOI: 10.1371/journal.pone.0025573] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 09/07/2011] [Indexed: 11/27/2022] Open
Abstract
The tellurium oxyanion tellurite induces oxidative stress in most microorganisms. In Escherichia coli, tellurite exposure results in high levels of oxidized proteins and membrane lipid peroxides, inactivation of oxidation-sensitive enzymes and reduced glutathione content. In this work, we show that tellurite-exposed E. coli exhibits transcriptional activation of the zwf gene, encoding glucose 6-phosphate dehydrogenase (G6PDH), which in turn results in augmented synthesis of reduced nicotinamide adenine dinucleotide phosphate (NADPH). Increased zwf transcription under tellurite stress results mainly from reactive oxygen species (ROS) generation and not from a depletion of cellular glutathione. In addition, the observed increase of G6PDH activity was paralleled by accumulation of glucose-6-phosphate (G6P), suggesting a metabolic flux shift toward the pentose phosphate shunt. Upon zwf overexpression, bacterial cells also show increased levels of antioxidant molecules (NADPH, GSH), better-protected oxidation-sensitive enzymes and decreased amounts of oxidized proteins and membrane lipids. These results suggest that by increasing NADPH content, G6PDH plays an important role in E. coli survival under tellurite stress.
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Affiliation(s)
- Juan M. Sandoval
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Felipe A. Arenas
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Claudio C. Vásquez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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