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Martins MC, Romão CV, Folgosa F, Borges PT, Frazão C, Teixeira M. How superoxide reductases and flavodiiron proteins combat oxidative stress in anaerobes. Free Radic Biol Med 2019; 140:36-60. [PMID: 30735841 DOI: 10.1016/j.freeradbiomed.2019.01.051] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 01/14/2019] [Accepted: 01/31/2019] [Indexed: 12/31/2022]
Abstract
Microbial anaerobes are exposed in the natural environment and in their hosts, even if transiently, to fluctuating concentrations of oxygen and its derived reactive species, which pose a considerable threat to their anoxygenic lifestyle. To counteract these stressful conditions, they contain a multifaceted array of detoxifying systems that, in conjugation with cellular repairing mechanisms and in close crosstalk with metal homeostasis, allow them to survive in the presence of O2 and reactive oxygen species. Some of these systems are shared with aerobes, but two families of enzymes emerged more recently that, although not restricted to anaerobes, are predominant in anaerobic microbes. These are the iron-containing superoxide reductases, and the flavodiiron proteins, endowed with O2 and/or NO reductase activities, which are the subject of this Review. A detailed account of their physicochemical, physiological and molecular mechanisms will be presented, highlighting their unique properties in allowing survival of anaerobes in oxidative stress conditions, and comparing their properties with the most well-known detoxifying systems.
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Affiliation(s)
- Maria C Martins
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Célia V Romão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Filipe Folgosa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Patrícia T Borges
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Carlos Frazão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Miguel Teixeira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
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2
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Antioxidant defence systems in the protozoan pathogen Giardia intestinalis. Mol Biochem Parasitol 2016; 206:56-66. [DOI: 10.1016/j.molbiopara.2015.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/26/2015] [Accepted: 12/01/2015] [Indexed: 01/03/2023]
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3
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Horch M, Utesch T, Hildebrandt P, Mroginski MA, Zebger I. Domain motions and electron transfer dynamics in 2Fe-superoxide reductase. Phys Chem Chem Phys 2016; 18:23053-66. [DOI: 10.1039/c6cp03666j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Theoretical studies on 2Fe-superoxide reductase provide mechanistic insights into structural dynamics and electron transfer efficiencies.
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Affiliation(s)
- Marius Horch
- Institut für Chemie
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | - Tillmann Utesch
- Institut für Chemie
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | - Peter Hildebrandt
- Institut für Chemie
- Technische Universität Berlin
- D-10623 Berlin
- Germany
| | | | - Ingo Zebger
- Institut für Chemie
- Technische Universität Berlin
- D-10623 Berlin
- Germany
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4
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Sheng Y, Abreu IA, Cabelli DE, Maroney MJ, Miller AF, Teixeira M, Valentine JS. Superoxide dismutases and superoxide reductases. Chem Rev 2014; 114:3854-918. [PMID: 24684599 PMCID: PMC4317059 DOI: 10.1021/cr4005296] [Citation(s) in RCA: 671] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Yuewei Sheng
- Department
of Chemistry and Biochemistry, University
of California Los Angeles, Los
Angeles, California 90095, United States
| | - Isabel A. Abreu
- Instituto
de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
- Instituto
de Biologia Experimental e Tecnológica, Av. da República,
Qta. do Marquês, Estação Agronómica Nacional,
Edificio IBET/ITQB, 2780-157, Oeiras, Portugal
| | - Diane E. Cabelli
- Chemistry
Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Michael J. Maroney
- Department
of Chemistry, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
| | - Anne-Frances Miller
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Miguel Teixeira
- Instituto
de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Joan Selverstone Valentine
- Department
of Chemistry and Biochemistry, University
of California Los Angeles, Los
Angeles, California 90095, United States
- Department
of Bioinspired Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
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Liochev SI. Free radicals: how do we stand them? Anaerobic and aerobic free radical (chain) reactions involved in the use of fluorogenic probes and in biological systems. Med Princ Pract 2014; 23:195-203. [PMID: 24356000 PMCID: PMC5586870 DOI: 10.1159/000357120] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 11/07/2013] [Indexed: 01/21/2023] Open
Abstract
Biologically significant conclusions have been based on the use of fluorogenic and luminogenic probes for the detection of reactive species. The basic mechanisms of the processes involved have not been satisfactorily elucidated. In the present work, the mechanism of the enzyme and photosensitized oxidation of NAD(P)H by resorufin is analyzed and appears to involve both aerobic and anaerobic free radical chain reactions. There are two major fallouts of this analysis. Many of the conclusions about the participation of radicals based on the use of probes such as resorufin and Amplex red need reevaluation. It is also concluded that anaerobic free radical reactions may be biologically significant, and the possible existence of enzymatic systems to eliminate certain free radicals is discussed.
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Horch M, Pinto AF, Utesch T, Mroginski MA, Romão CV, Teixeira M, Hildebrandt P, Zebger I. Reductive activation and structural rearrangement in superoxide reductase: a combined infrared spectroscopic and computational study. Phys Chem Chem Phys 2014; 16:14220-30. [DOI: 10.1039/c4cp00884g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Local and global structural changes that enable reductive activation of superoxide reductase are revealed by a combined approach of infrared difference spectroscopy and computational methods.
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Affiliation(s)
- M. Horch
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - A. F. Pinto
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República (EAN)
- P-2780-157 Oeiras, Portugal
| | - T. Utesch
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - M. A. Mroginski
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - C. V. Romão
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República (EAN)
- P-2780-157 Oeiras, Portugal
| | - M. Teixeira
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República (EAN)
- P-2780-157 Oeiras, Portugal
| | - P. Hildebrandt
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - I. Zebger
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
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Thorgersen MP, Stirrett K, Scott RA, Adams MWW. Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus. Proc Natl Acad Sci U S A 2012; 109:18547-52. [PMID: 23093671 PMCID: PMC3494905 DOI: 10.1073/pnas.1208605109] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The anaerobic archaeon Pyrococcus furiosus grows by fermenting carbohydrates producing H(2), CO(2), and acetate. We show here that it is surprisingly tolerant to oxygen, growing well in the presence of 8% (vol/vol) O(2). Although cell growth and acetate production were not significantly affected by O(2), H(2) production was reduced by 50% (using 8% O(2)). The amount of H(2) produced decreased in a linear manner with increasing concentrations of O(2) over the range 2-12% (vol/vol), and for each mole of O(2) consumed, the amount of H(2) produced decreased by approximately 2 mol. The recycling of H(2) by the two cytoplasmic hydrogenases appeared not to play a role in O(2) resistance because a mutant strain lacking both enzymes was not more sensitive to O(2) than the parent strain. Decreased H(2) production was also not due to inactivation of the H(2)-producing, ferredoxin-dependent membrane-bound hydrogenase because its activity was unaffected by O(2) exposure. Electrons from carbohydrate oxidation must therefore be diverted to relieve O(2) stress at the level of reduced ferredoxin before H(2) production. Deletion strains lacking superoxide reductase (SOR) and putative flavodiiron protein A showed increased sensitivity to O(2), indicating that these enzymes play primary roles in resisting O(2). However, a mutant strain lacking the proposed electron donor to SOR, rubredoxin, was unaffected in response to O(2). Hence, electrons from sugar oxidation normally used to produce H(2) are diverted to O(2) detoxification by SOR and putative flavodiiron protein A, but the electron flow pathway from ferredoxin does not necessarily involve rubredoxin.|
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Affiliation(s)
- Michael P. Thorgersen
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602
| | - Karen Stirrett
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602
| | - Robert A. Scott
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602
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Testa F, Mastronicola D, Cabelli DE, Bordi E, Pucillo LP, Sarti P, Saraiva LM, Giuffrè A, Teixeira M. The superoxide reductase from the early diverging eukaryote Giardia intestinalis. Free Radic Biol Med 2011; 51:1567-74. [PMID: 21839165 DOI: 10.1016/j.freeradbiomed.2011.07.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 06/02/2011] [Accepted: 07/20/2011] [Indexed: 12/13/2022]
Abstract
Unlike superoxide dismutases (SODs), superoxide reductases (SORs) eliminate superoxide anion (O(2)(•-)) not through its dismutation, but via reduction to hydrogen peroxide (H(2)O(2)) in the presence of an electron donor. The microaerobic protist Giardia intestinalis, responsible for a common intestinal disease in humans, though lacking SOD and other canonical reactive oxygen species-detoxifying systems, is among the very few eukaryotes encoding a SOR yet identified. In this study, the recombinant SOR from Giardia (SOR(Gi)) was purified and characterized by pulse radiolysis and stopped-flow spectrophotometry. The protein, isolated in the reduced state, after oxidation by superoxide or hexachloroiridate(IV), yields a resting species (T(final)) with Fe(3+) ligated to glutamate or hydroxide depending on pH (apparent pK(a)=8.7). Although showing negligible SOD activity, reduced SOR(Gi) reacts with O(2)(•-) with a pH-independent second-order rate constant k(1)=1.0×10(9) M(-1) s(-1) and yields the ferric-(hydro)peroxo intermediate T(1); this in turn rapidly decays to the T(final) state with pH-dependent rates, without populating other detectable intermediates. Immunoblotting assays show that SOR(Gi) is expressed in the disease-causing trophozoite of Giardia. We propose that the superoxide-scavenging activity of SOR in Giardia may promote the survival of this air-sensitive parasite in the fairly aerobic proximal human small intestine during infection.
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Affiliation(s)
- Fabrizio Testa
- Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology, Sapienza Università di Roma, I-00185 Rome, Italy
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Lucchetti-Miganeh C, Goudenège D, Thybert D, Salbert G, Barloy-Hubler F. SORGOdb: Superoxide Reductase Gene Ontology curated DataBase. BMC Microbiol 2011; 11:105. [PMID: 21575179 PMCID: PMC3116461 DOI: 10.1186/1471-2180-11-105] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 05/16/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Superoxide reductases (SOR) catalyse the reduction of superoxide anions to hydrogen peroxide and are involved in the oxidative stress defences of anaerobic and facultative anaerobic organisms. Genes encoding SOR were discovered recently and suffer from annotation problems. These genes, named sor, are short and the transfer of annotations from previously characterized neelaredoxin, desulfoferrodoxin, superoxide reductase and rubredoxin oxidase has been heterogeneous. Consequently, many sor remain anonymous or mis-annotated. DESCRIPTION SORGOdb is an exhaustive database of SOR that proposes a new classification based on domain architecture. SORGOdb supplies a simple user-friendly web-based database for retrieving and exploring relevant information about the proposed SOR families. The database can be queried using an organism name, a locus tag or phylogenetic criteria, and also offers sequence similarity searches using BlastP. Genes encoding SOR have been re-annotated in all available genome sequences (prokaryotic and eukaryotic (complete and in draft) genomes, updated in May 2010). CONCLUSIONS SORGOdb contains 325 non-redundant and curated SOR, from 274 organisms. It proposes a new classification of SOR into seven different classes and allows biologists to explore and analyze sor in order to establish correlations between the class of SOR and organism phenotypes. SORGOdb is freely available at http://sorgo.genouest.org/index.php.
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Affiliation(s)
- Céline Lucchetti-Miganeh
- CNRS UMR 6026, ICM, Equipe Sp@rte, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes, France.
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Abstract
Dr. Irwin Fridovich (Ph.D., 1955) is recognized here as a Redox Pioneer because as first/last author he has published at least 1 paper on antioxidant/redox biology that has been cited over 1000 times and has published at least 10 papers each cited over 100 times. In collaboration with his graduate student, Joe McCord, Dr. Fridovich discovered the activity of superoxide dismutase (SOD). Subsequently, he and his colleagues demonstrated that the enzyme is ubiquitous among aerobic biota and comprises a critical defense against oxidative stress. With coworkers, Dr. Fridovich identified the first physiological targets of superoxide, the iron-sulfur clusters of dehydratases. They also showed that SOD is just one of several strategies by which cells fend off oxidative stress. It is now clear that organisms are chronically exposed to endogenous superoxide; further, microbes, plants, and mammals all employ superoxide as a weapon to poison their competitors. Thus, the achievement of Fridovich's laboratory was not only the seminal discovery of SOD but also the painstaking work over the subsequent decades that illuminated its place in biology.
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Affiliation(s)
- James A Imlay
- Department of Microbiology, University of Illinois, Urbana, Illinois, USA
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11
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Pinto AF, Rodrigues JV, Teixeira M. Reductive elimination of superoxide: Structure and mechanism of superoxide reductases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:285-97. [PMID: 19857607 DOI: 10.1016/j.bbapap.2009.10.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 10/12/2009] [Accepted: 10/14/2009] [Indexed: 10/20/2022]
Abstract
Superoxide anion is among the deleterious reactive oxygen species, towards which all organisms have specialized detoxifying enzymes. For quite a long time, superoxide elimination was thought to occur through its dismutation, catalyzed by Fe, Cu, and Mn or, as more recently discovered, by Ni-containing enzymes. However, during the last decade, a novel type of enzyme was established that eliminates superoxide through its reduction: the superoxide reductases, which are spread among anaerobic and facultative microorganisms, from the three life kingdoms. These enzymes share the same unique catalytic site, an iron ion bound to four histidines and a cysteine that, in its reduced form, reacts with superoxide anion with a diffusion-limited second order rate constant of approximately 10(9) M(-1) s(-1). In this review, the properties of these enzymes will be thoroughly discussed.
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Affiliation(s)
- Ana Filipa Pinto
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
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12
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Brioukhanov AL. Nonheme iron proteins as an alternative system of antioxidant defense in the cells of strictly anaerobic microorganisms: A review. APPL BIOCHEM MICRO+ 2008. [DOI: 10.1134/s0003683808040017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Pereira AS, Tavares P, Folgosa F, Almeida RM, Moura I, Moura JJG. Superoxide Reductases. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Alice S. Pereira
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Pedro Tavares
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Filipe Folgosa
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Rui M. Almeida
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Isabel Moura
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - José J. G. Moura
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
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Auchère F, Pauleta SR, Tavares P, Moura I, Moura JJG. Kinetics studies of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and superoxide reductases. J Biol Inorg Chem 2006; 11:433-44. [PMID: 16544159 DOI: 10.1007/s00775-006-0090-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Accepted: 02/03/2006] [Indexed: 10/24/2022]
Abstract
In this work we present a kinetic study of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and members of the three different classes of superoxide reductases (SORs). SORs from the sulfate-reducing bacteria Desulfovibrio vulgaris (Dv) and D. gigas (Dg) were chosen as prototypes of classes I and II, respectively, while SOR from the syphilis spirochete Treponema pallidum (Tp) was representative of class III. Our results show evidence for different behaviors of SORs toward electron acceptance, with a trend to specificity for the electron donor and acceptor from the same organism. Comparison of the different kapp values, 176.9+/-25.0 min(-1) in the case of the Tp/Tp electron transfer, 31.8+/-3.6 min(-1) for the Dg/Dg electron transfer, and 6.9+/-1.3 min(-1) for Dv/Dv, could suggest an adaptation of the superoxide-mediated electron transfer efficiency to various environmental conditions. We also demonstrate that, in Dg, another iron-sulfur protein, a desulforedoxin, is able to transfer electrons to SOR more efficiently than rubredoxin, with a kapp value of 108.8+/-12.0 min(-1), and was then assigned as the potential physiological electron donor in this organism.
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Affiliation(s)
- Françoise Auchère
- REQUIMTE-Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal
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Kawasaki S, Watamura Y, Ono M, Watanabe T, Takeda K, Niimura Y. Adaptive responses to oxygen stress in obligatory anaerobes Clostridium acetobutylicum and Clostridium aminovalericum. Appl Environ Microbiol 2006; 71:8442-50. [PMID: 16332833 PMCID: PMC1317462 DOI: 10.1128/aem.71.12.8442-8450.2005] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium acetobutylicum and Clostridium aminovalericum, both obligatory anaerobes, grow normally after growth conditions are changed from anoxic to microoxic, where the cells consume oxygen proficiently. In C. aminovalericum, a gene encoding a previously characterized H2O-forming NADH oxidase, designated noxA, was cloned and sequenced. The expression of noxA was strongly upregulated within 10 min after the growth conditions were altered to a microoxic state, indicating that C. aminovalericum NoxA is involved in oxygen metabolism. In C. acetobutylicum, genes suggested to be involved in oxygen metabolism and genes for reactive oxygen species (ROS) scavenging were chosen from the genome database. Although no clear orthologue of C. aminovalericum NoxA was found, Northern blot analysis identified many O2-responsive genes (e.g., a gene cluster [CAC2448 to CAC2452] encoding an NADH rubredoxin oxidoreductase-A-type flavoprotein-desulfoferrodoxin homologue-MerR family-like protein-flavodoxin, an operon [CAC1547 to CAC1549] encoding a thioredoxin-thioredoxin reductase-glutathione peroxidase-like protein, an operon [CAC1570 and CAC1571] encoding two glutathione peroxidase-like proteins, and genes encoding thiol peroxidase, bacterioferritin comigratory proteins, and superoxide dismutase) whose expression was quickly and synchronously upregulated within 10 min after flushing with 5% O2. The corresponding enzyme activities, such as NAD(P)H-dependent peroxide (H2O2 and alkyl hydroperoxides) reductase, were highly induced, indicating that microoxic growth of C. acetobutylicum is associated with the expression of a number of genes for oxygen metabolism and ROS scavenging.
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Affiliation(s)
- Shinji Kawasaki
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Setagaya-ku, Tokyo 156-8502, Japan.
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16
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Jean D, Briolat V, Reysset G. Oxidative stress response in Clostridium perfringens. MICROBIOLOGY-SGM 2004; 150:1649-1659. [PMID: 15184551 DOI: 10.1099/mic.0.27017-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Clostridium perfringens, a strictly anaerobic bacterium, is able to survive when exposed to oxygen for short periods of time and exhibits a complex adaptive response to reactive oxygen species, both under aerobic and anaerobic conditions. However, this adaptive response is not completely understood. C. perfringens possesses specialized genes that might be involved in this adaptive process, such as those encoding superoxide dismutase (SOD), superoxide reductase and alkyl hydroperoxide reductase, but their contribution to the oxidative stress response and their control mechanisms are unknown. By a combination of functional complementation of Escherichia coli strains impaired in either SOD, alkyl hydroperoxide reductase (AhpC) or catalase activity (Cat), transcription analysis and characterization of mutants impaired in regulatory genes, it was concluded that: (i) the product of the sod gene is certainly essential to scavenge superoxide radicals, (ii) the ahpC gene, which is fully induced in all oxidative stress conditions, is probably involved in the scavenging of all intracellular peroxides, (iii) the three rubrerythrin (rbr) genes of C. perfringens do not encode proteins with in vivo H(2)O(2) reductase activity, and (iv) the two rubredoxin (rub) genes do not contribute to the hypothetical superoxide reductase activity, but are likely to belong to an electron transfer chain involved in energy metabolism.
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Affiliation(s)
- Delphine Jean
- Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, 28 rue du docteur Roux, 75724 Paris Cedex 15, France
| | - Valérie Briolat
- Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, 28 rue du docteur Roux, 75724 Paris Cedex 15, France
| | - Gilles Reysset
- Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, 28 rue du docteur Roux, 75724 Paris Cedex 15, France
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17
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Kovacs JA. Synthetic analogues of cysteinate-ligated non-heme iron and non-corrinoid cobalt enzymes. Chem Rev 2004; 104:825-48. [PMID: 14871143 PMCID: PMC4487544 DOI: 10.1021/cr020619e] [Citation(s) in RCA: 226] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Julie A Kovacs
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, USA
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Nivière V, Fontecave M. Discovery of superoxide reductase: an historical perspective. J Biol Inorg Chem 2004; 9:119-23. [PMID: 14722742 DOI: 10.1007/s00775-003-0519-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Accepted: 12/15/2003] [Indexed: 11/30/2022]
Abstract
For more than 30 years, the only enzymatic system known to catalyze the elimination of superoxide was superoxide dismutase, SOD. SOD has been found in almost all organisms living in the presence of oxygen, including some anaerobic bacteria, supporting the notion that superoxide is a key and general component of oxidative stress. Recently, a new concept in the field of the mechanisms of cellular defense against superoxide has emerged. It was discovered that elimination of superoxide in some anaerobic and microaerophilic bacteria could occur by reduction, a reaction catalyzed by a small metalloenzyme thus named superoxide reductase, SOR. Having played a major role in this discovery, we describe here how the concept of superoxide reduction emerged and how it was experimentally substantiated independently in our laboratory.
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Affiliation(s)
- Vincent Nivière
- Laboratoire de Chimie et Biochimie des Centres Redox Biologiques, DRDC-CB, UMR CEA/CNRS/Université Joseph Fourier no. 5047, CEA Grenoble, 17 Avenue des Martyrs, 38054 Grenoble Cedex 9, France.
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19
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Emerson JP, Coulter ED, Phillips RS, Kurtz DM. Kinetics of the superoxide reductase catalytic cycle. J Biol Chem 2003; 278:39662-8. [PMID: 12900405 DOI: 10.1074/jbc.m306488200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The steady state kinetics of a Desulfovibrio (D.) vulgaris superoxide reductase (SOR) turnover cycle, in which superoxide is catalytically reduced to hydrogen peroxide at a [Fe(His)4(Cys)] active site, are reported. A proximal electron donor, rubredoxin, was used to supply reducing equivalents from NADPH via ferredoxin: NADP+ oxidoreductase, and xanthine/xanthine oxidase was used to provide a calibrated flux of superoxide. SOR turnover in this system was well coupled, i.e. approximately 2O*2 reduced:NADPH oxidized over a 10-fold range of superoxide flux. The reduction of the ferric SOR active site by reduced rubredoxin was independently measured to have a second-order rate constant of approximately 1 x 10(6) m-1 s-1. Analysis of the kinetics showed that: (i) 1 microM SOR can convert a 10 microM/min superoxide flux to a steady state superoxide concentration of 10(-10) m, during which SOR turns over about once every 6 s, (ii) the diffusion-controlled reaction of reduced SOR with superoxide is the slowest process during turnover, and (iii) neither ligation nor deligation of the active site carboxylate of SOR limits the turnover rate. An intracellular SOR concentration on the order of 10 microM is estimated to be the minimum required for lowering superoxide to sublethal levels in aerobically growing SOD knockout mutants of Escherichia coli. SORs from Desulfovibrio gigas and Treponema pallidum showed similar turnover rates when substituted for the D. vulgaris SOR, whereas superoxide dismutases showed no SOR activity in our assay. These results provide quantitative support for previous suggestions that, in times of oxidative stress, SORs efficiently divert intracellular reducing equivalents to superoxide.
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Affiliation(s)
- Joseph P Emerson
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA
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Clay MD, Cosper CA, Jenney FE, Adams MWW, Johnson MK. Nitric oxide binding at the mononuclear active site of reduced Pyrococcus furiosus superoxide reductase. Proc Natl Acad Sci U S A 2003; 100:3796-801. [PMID: 12655067 PMCID: PMC153001 DOI: 10.1073/pnas.0636858100] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) has been used as a substrate analog to explore the structural and electronic determinants of enzymatic superoxide reduction at the mononuclear iron active site of Pyrococcus furiosus superoxide reductase (SOR) through the use of EPR, resonance Raman, Fourier transform IR, UV-visible absorption, and variable-temperature variable-field magnetic CD spectroscopies. The NO adduct of reduced SOR is shown to have a near-axial S = 32 ground state with ED = 0.06 and D = 12 +/- 2 cm(-1) (where D and E are the axial and rhombic zero-field splitting parameters, respectively) and the UV-visible absorption and magnetic CD spectra are dominated by an out-of-plane NO(-)(pi*)-to-Fe(3+)(dpi) charge-transfer transition, polarized along the zero-field splitting axis. Resonance Raman studies indicate that the NO adduct is six-coordinate with NO ligated in a bent conformation trans to the cysteinyl S, as evidenced by the identification of nu(N-O) at 1,721 cm(-1), nu(Fe-NO) at 475 cm(-1), and nu(Fe-S(Cys), at 291 cm(-1), via (34)S and (15)NO isotope shifts. The electronic and vibrational properties of the S = 32 (FeNO)(7) unit are rationalized in terms of a limiting formulation involving a high-spin (S = 52) Fe(3+) center antiferromagnetically coupled to a (S = 1) NO(-) anion, with a highly covalent Fe(3+)-NO(-) interaction. The results support a catalytic mechanism for SOR, with the first step involving oxidative addition of superoxide to form a ferric-peroxo intermediate, and indicate the important roles that the Fe spin state and the trans cysteinate ligand play in effecting superoxide reduction and peroxide release.
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Affiliation(s)
- Michael D Clay
- Department of Chemistry, University of Georgia, Athens, GA 30602, USA
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21
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Emerson JP, Cabelli DE, Kurtz DM. An engineered two-iron superoxide reductase lacking the [Fe(SCys)4] site retains its catalytic properties in vitro and in vivo. Proc Natl Acad Sci U S A 2003; 100:3802-7. [PMID: 12637682 PMCID: PMC153002 DOI: 10.1073/pnas.0537177100] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Superoxide reductases (SORs) contain a characteristic square-pyramidal [Fe(NHis)(4)(SCys)] active site that catalyzes reduction of superoxide to hydrogen peroxide in several anaerobic bacteria and archaea. Some SORs, referred to as two-iron SORs (2Fe-SORs), also contain a lower-potential [Fe(SCys)(4)] site that is presumed to have an electron transfer function. However, the intra- and inter-subunit distances between [Fe(SCys)(4)] and [Fe(NHis)(4)(SCys)] iron centers within the 2Fe-SOR homodimer seem too long for efficient electron transfer between these sites. The possible role of the [Fe(SCys)(4)] site in 2Fe-SORs was addressed in this work by examination of an engineered Desulfovibrio vulgaris 2Fe-SOR variant, C13S, in which one ligand residue of the [Fe(SCys)(4)] site, cysteine 13, was changed to serine. This single amino acid residue change destroyed the native [Fe(SCys)(4)] site with complete loss of its iron, but left the [Fe(NHis)(4)(SCys)] site and the protein homodimer intact. The spectroscopic, redox and superoxide reactivity properties of the [Fe(NHis)(4)(SCys)] site in the C13S variant were nearly indistinguishable from those of the wild-type 2Fe-SOR. Aerobic growth complementation of a superoxide dismutase (SOD)-deficient Escherichia coli strain showed that the presence of the [Fe(NHis)(4)(SCys)] site in C13S 2Fe-SOR was apparently sufficient to catalyze reduction of the intracellular superoxide to nonlethal levels. As is the case for the wild-type protein, C13S 2Fe-SOR did not show any detectable SOD activity, i.e., destruction of the [Fe(SCys)(4)] site did not unmask latent SOD activity of the [Fe(NHis)(4)(SCys)] site. Possible alternative roles for the [Fe(SCys)(4)] site in 2Fe-SORs are considered.
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Affiliation(s)
- Joseph P Emerson
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30605, USA
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Hazlett KRO, Cox DL, Sikkink RA, Auch'ere F, Rusnak F, Radolf JD. Contribution of neelaredoxin to oxygen tolerance by Treponema pallidum. Methods Enzymol 2002; 353:140-56. [PMID: 12078490 DOI: 10.1016/s0076-6879(02)53044-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Karsten R O Hazlett
- Center for Microbial Pathogenesis, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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23
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Rusnak F, Ascenso C, Moura I, Moura JJG. Superoxide reductase activities of neelaredoxin and desulfoferrodoxin metalloproteins. Methods Enzymol 2002; 349:243-58. [PMID: 11912914 DOI: 10.1016/s0076-6879(02)49339-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Superoxide reductases have now been well characterized from several organisms. Unique biochemical features include the ability of the reduced enzyme to react with O2- but not dioxygen (reduced SORs are stable in an aerobic atmosphere for hours). Future biochemical assays that measure the reaction of SOR with O2- should take into account the difficulties of assaying O2- directly and the myriad of redox reactions that can take place between components in the assay, for example, direct electron transfer between cytochrome c and Dfx. Future prospects include further delineation of the reaction mechanisms, characterization of the putative (hydro)peroxo intermediate, and studies that uncover the components between reduced pyridine nucleotides and SOR in the metabolic pathway responsible for O2- detoxification.
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Affiliation(s)
- Frank Rusnak
- Section of Hematology Research, Department of Biochemistry and Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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24
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Emerson JP, Coulter ED, Cabelli DE, Phillips RS, Kurtz DM. Kinetics and mechanism of superoxide reduction by two-iron superoxide reductase from Desulfovibrio vulgaris. Biochemistry 2002; 41:4348-57. [PMID: 11914081 DOI: 10.1021/bi0119159] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Superoxide reductases (SORs) contain a novel square pyramidal ferrous [Fe(NHis)(4)(SCys)] site that rapidly reduces superoxide to hydrogen peroxide. Here we report extensive pulse radiolysis studies on recombinant two-iron SOR (2Fe-SOR) from Desulfovibrio vulgaris. The results support and elaborate on our originally proposed scheme for reaction of the [Fe(NHis)(4)(SCys)] site with superoxide [Coulter, E. D., Emerson, J. E., Kurtz, D. M., Jr., and Cabelli, D. E. (2000) J. Am. Chem. Soc. 122, 11555-11556]. This scheme consists of second-order diffusion-controlled formation of an intermediate absorbing at approximately 600 nm, formulated as a ferric-(hydro)peroxo species, and its decay to the carboxylate-ligated ferric [Fe(NHis)(4)(SCys)] site with loss of hydrogen peroxide. The second-order rate constant for formation of the 600-nm intermediate is essentially pH-independent (pH 5-9.5), shows no D(2)O solvent isotope effect at pH 7.7, and decreases with increasing ionic strength. These data indicate that formation of the intermediate does not involve a rate-determining protonation, and are consistent with interaction of the incoming superoxide anion with a positive charge at or near the ferrous [Fe(NHis)(4)(SCys)] site. The rate constant for decay of the 600-nm intermediate follows the pH-dependent rate law: k(2)(obs) = k(2)'[H(+)] + k(2)' ' and shows a significant D(2)O solvent isotope effect at pH 7.7. The values of k(2)' and k(2)' ' indicate that the 600-nm intermediate decays via diffusion-controlled protonation at acidic pHs and a first-order process involving either water or a water-exchangeable proton on the protein at basic pHs. The formation and decay rate constants for an E47A variant of 2Fe-SOR are not significantly perturbed from their wild-type values, indicating that the conserved glutamate carboxylate does not directly displace the (hydro)peroxo ligand of the intermediate at basic pHs. The kinetics of a K48A variant are consistent with participation of the lysyl side chain in directing the superoxide toward the active site and in directing the protonation pathway of the ferric-(hydro)peroxo intermediate toward release of hydrogen peroxide.
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Affiliation(s)
- Joseph P Emerson
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA
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25
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Clay MD, Jenney FE, Hagedoorn PL, George GN, Adams MWW, Johnson MK. Spectroscopic studies of Pyrococcus furiosus superoxide reductase: implications for active-site structures and the catalytic mechanism. J Am Chem Soc 2002; 124:788-805. [PMID: 11817955 DOI: 10.1021/ja016889g] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The combination of UV/visible/NIR absorption, CD and variable-temperature magnetic circular dichroism (VTMCD), EPR, and X-ray absorption (XAS) spectroscopies has been used to investigate the electronic and structural properties of the oxidized and reduced forms of Pyrococcus furiosus superoxide reductase (SOR) as a function of pH and exogenous ligand binding. XAS shows that the mononuclear ferric center in the oxidized enzyme is very susceptible to photoreduction in the X-ray beam. This observation facilitates interpretation of ground- and excited-state electronic properties and the EXAFS results for the oxidized enzyme in terms of the published X-ray crystallographic data (Yeh, A. P.; Hu, Y.; Jenney, F. E.; Adams, M. W. W.; Rees, D. C. Biochemistry 2000, 39, 2499-2508). In the oxidized state, the mononuclear ferric active site has octahedral coordination with four equatorial histidyl ligands and axial cysteinate and monodentate glutamate ligands. Fe EXAFS are best fit by one Fe-S at 2.36 A and five Fe-N/O at an average distance of 2.12 A. The EPR-determined spin Hamiltonian parameters for the high-spin (S = (5)/(2)) ferric site in the resting enzyme, D = -0.50 +/- 0.05 cm(-1) and E/D = 0.06, are consistent with tetragonally compressed octahedral coordination geometry. UV/visible absorption and VTMCD studies facilitate resolution and assignment of pi His --> Fe(3+)(t(2g)) and (Cys)S(p) --> Fe(3+)(t(2g)) charge-transfer transitions, and the polarizations deduced from MCD saturation magnetization studies indicate that the zero-field splitting (compression) axis corresponds to one of the axes with trans-histidyl ligands. EPR and VTMCD studies provide evidence of azide, ferrocyanide, hydroxide, and cyanide binding via displacement of the glutamate ligand. For azide, ferrocyanide, and hydroxide, ligand binding occurs with retention of the high-spin (S = 5/2) ground state (E/D = 0.27 and D < 0 for azide and ferrocyanide; E/D = 0.25 and D = +1.1 +/- 0.2 cm(-1) for hydroxide), whereas cyanide binding results in a low-spin (S = 1/2) species (g = 2.29, 2.25, 1.94). The ground-state and charge-transfer/ligand-field excited-state properties of the low-spin cyanide-bound derivative are shown to be consistent with a tetragonally elongated octahedral coordination with the elongation axis corresponding to an axis with trans-histidyl ligands. In the reduced state, the ferrous site of SOR is shown to have square-pyramidal coordination geometry in frozen solution with four equatorial histidines and one axial cysteine on the basis of XAS and UV and NIR VTMCD studies. Fe EXAFS are best fit by one Fe-S at 2.37 A and four Fe-N/O at an average distance of 2.15 A. VTMCD reveals a high-spin (S = 2) ferrous site with (Cys)S(p) --> Fe(2+) charge-transfer transitions in the UV region and (5)T(2g) --> (5)E(g) ligand-field transitions in the NIR region at 12400 and <5000 cm(-1). The ligand-field bands indicate square-pyramidal coordination geometry with 10Dq < 8700 cm(-1) and a large excited-state splitting, Delta (5)E(g) > 7400 cm(-1). Analysis of MCD saturation magnetization data leads to ground-state zero-field splitting parameters for the S = 2 ground state, D approximately +10 cm(-1) and E/D approximately 0.1, and complete assessment of ferrous d-orbital splitting. Azide binds weakly at the vacant coordination site of reduced SOR to give a coordination geometry intermediate between octahedral and square pyramidal with 10Dq = 9700 cm(-1) and Delta (5)E(g) = 4800 cm(-1). Cyanide binding results in an octahedral ferrous site with 10Dq = 10,900 cm(-1) and Delta (5)E(g) = 1750 cm(-1). The ability to bind exogenous ligands to both the ferrous and ferric sites of SOR is consistent with an inner-sphere catalytic mechanism involving superoxide binding at the ferrous site to yield a ferric-(hydro)peroxo intermediate. The structural and electronic properties of the SOR active site are discussed in relation to the role and bonding of the axial cysteine residue and the recent proposals for the catalytic mechanism.
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Affiliation(s)
- Michael D Clay
- Department of Chemistry and the Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA
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Shearer J, Nehring J, Lovell S, Kaminsky W, Kovacs JA. Modeling the reactivity of superoxide reducing metalloenzymes with a nitrogen and sulfur coordinated iron complex. Inorg Chem 2001; 40:5483-4. [PMID: 11599942 PMCID: PMC4487530 DOI: 10.1021/ic010221l] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason Shearer
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Jennifer Nehring
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Scott Lovell
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Werner Kaminsky
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Julie A. Kovacs
- Department of Chemistry, University of Washington, Seattle, Washington 98195
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Coulter ED, Kurtz DM. A role for rubredoxin in oxidative stress protection in Desulfovibrio vulgaris: catalytic electron transfer to rubrerythrin and two-iron superoxide reductase. Arch Biochem Biophys 2001; 394:76-86. [PMID: 11566030 DOI: 10.1006/abbi.2001.2531] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Desulfovibrio vulgaris rubredoxin, which contains a single [Fe(SCys)4] site, is shown to be a catalytically competent electron donor to two enzymes from the same organism, namely, rubrerythrin and two-iron superoxide reductase (a.k.a. rubredoxin oxidoreductase or desulfoferrodoxin). These two enzymes have been implicated in catalytic reduction of hydrogen peroxide and superoxide, respectively, during periods of oxidative stress in D. vulgaris, but their proximal electron donors had not been characterized. We further demonstrate the incorrectness of a previous report that rubredoxin is not an electron donor to the superoxide reductase and describe convenient assays for demonstrating the catalytic competence of all three proteins in their respective functions. Rubrerythrin is shown to be an efficient rubredoxin peroxidase in which the rubedoxin:hydrogen peroxide redox stoichiometry is 2:1 mol:mol. Using spinach ferredoxin-NADP+ oxidoreductase (FNR) as an artificial, but proficient, NADPH:rubredoxin reductase, rubredoxin was further found to catalyze rapid and complete reduction of all Fe3+ to Fe2+ in rubrerythrin by NADPH under anaerobic conditions. The combined system, FNR/rubredoxin/rubrerythrin, was shown to function as a catalytically competent NADPH peroxidase. Another small rubredoxin-like D. vulgaris protein, Rdl, could not substitute for rubredoxin as a peroxidase substrate of rubrerythrin. Similarly, D. vulgaris rubredoxin was demonstrated to efficiently catalyze reduction of D. vulgaris two-iron superoxide reductase and, when combined with FNR, to function as an NADPH:superoxide oxidoreductase. We suggest that, during periods of oxidative stress, rubredoxin could divert electron flow from the electron transport chain of D. vulgaris to rubrerythrin and superoxide reductase, thereby simultaneously protecting autoxidizable redox enzymes and lowering intracellular hydrogen peroxide and superoxide levels.
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Affiliation(s)
- E D Coulter
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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Silva G, LeGall J, Xavier AV, Teixeira M, Rodrigues-Pousada C. Molecular characterization of Desulfovibrio gigas neelaredoxin, a protein involved in oxygen detoxification in anaerobes. J Bacteriol 2001; 183:4413-20. [PMID: 11443075 PMCID: PMC95335 DOI: 10.1128/jb.183.4.4413-4420.2001] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Desulfovibrio gigas neelaredoxin is an iron-containing protein of 15 kDa, having a single iron site with a His(4)Cys coordination. Neelaredoxins and homologous proteins are widespread in anaerobic prokaryotes and have superoxide-scavenging activity. To further understand its role in anaerobes, its genomic organization and expression in D. gigas were studied and its ability to complement Escherichia coli superoxide dismutase deletion mutant was assessed. In D. gigas, neelaredoxin is transcribed as a monocistronic mRNA of 500 bases as revealed by Northern analysis. Putative promoter elements resembling sigma(70) recognition sequences were identified. Neelaredoxin is abundantly and constitutively expressed, and its expression is not further induced during treatment with O(2) or H(2)O(2). The neelaredoxin gene was cloned by PCR and expressed in E. coli, and the protein was purified to homogeneity. The recombinant neelaredoxin has spectroscopic properties identical to those observed for the native one. Mutations of Cys-115, one of the iron ligands, show that this ligand is essential for the activity of neelaredoxin. In an attempt to elucidate the function of neelaredoxin within the cell, it was expressed in an E. coli mutant deficient in cytoplasmic superoxide dismutases (sodA sodB). Neelaredoxin suppresses the deleterious effects produced by superoxide, indicating that it is involved in oxygen detoxification in the anaerobe D. gigas.
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Affiliation(s)
- G Silva
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
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29
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da Costa PN, Romão CV, LeGall J, Xavier AV, Melo E, Teixeira M, Saraiva LM. The genetic organization of Desulfovibrio desulphuricans ATCC 27774 bacterioferritin and rubredoxin-2 genes: involvement of rubredoxin in iron metabolism. Mol Microbiol 2001; 41:217-27. [PMID: 11454214 DOI: 10.1046/j.1365-2958.2001.02509.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The anaerobic bacterium Desulfovibrio desulphuricans ATCC 27774 contains a unique bacterioferritin, isolated with a stable di-iron centre and having iron-coproporphyrin III as its haem cofactor, as well as a type 2 rubredoxin with an unusual spacing of four amino acid residues between the first two binding cysteines. The genes encoding for these two proteins were cloned and sequenced. The deduced amino acid sequence of the bacterioferritin shows that it is among the most divergent members of this protein family. Most interestingly, the bacterioferritin and rubredoxin-2 genes form a dicistronic operon, which reflects the direct interaction between the two proteins. Indeed, bacterioferritin and rubredoxin-2 form a complex in vitro, as shown by the significant increase in the anisotropy and decay times of the fluorescence of rubredoxin-2 tryptophan(s) when mixed with bacterioferritin. In addition, rubredoxin-2 donates electrons to bacterioferritin. This is the first identification of an electron donor to a bacterioferritin and shows the involvement of rubredoxin-2 in iron metabolism. Furthermore, analysis of the genomic data for anaerobes suggests that rubredoxins play a general role in iron metabolism and oxygen detoxification in these prokaryotes.
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Affiliation(s)
- P N da Costa
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, R. da Quinta Grande 6, 2780-156 Oeiras, Portugal
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Liochev SI, Fridovich I. The Oxidation of 3-Hydroxyanthranilic Acid by Cu,Zn Superoxide Dismutase: Mechanism and Possible Consequences. Arch Biochem Biophys 2001; 388:281-4. [PMID: 11368166 DOI: 10.1006/abbi.2001.2296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cu,Zn SOD, but not Mn SOD, catalyzes the oxidation of 3-hydroxyanthranilic acid (3-HA) under aerobic conditions. In the absence of O2, the Cu(II) of the enzyme is reduced by 3-HA. One plausible mechanism involves the reduction of the active site Cu(II) to Cu(I), which is then reoxidized by the O2- generated by autoxidation of the anthranilyl or other radicals on the pathway to cinnabarinate. We may call this the superoxide reductase, or SOR, mechanism. Another possibility invokes direct reoxidation of the active site Cu(I) by the anthranilyl, or other organic radicals, or by the peroxyl radicals generated by addition of O2 to these organic radicals. Such oxidations catalyzed by Cu,Zn SOD could account for the deleterious effects of the mutant Cu,Zn SODs associated with familial amyotrophic lateral sclerosis and of the overproduction or overadministration of wild-type Cu,Zn SOD.
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Affiliation(s)
- S I Liochev
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Lumppio HL, Shenvi NV, Summers AO, Voordouw G, Kurtz DM. Rubrerythrin and rubredoxin oxidoreductase in Desulfovibrio vulgaris: a novel oxidative stress protection system. J Bacteriol 2001; 183:101-8. [PMID: 11114906 PMCID: PMC94855 DOI: 10.1128/jb.183.1.101-108.2001] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2000] [Accepted: 10/11/2000] [Indexed: 11/20/2022] Open
Abstract
Evidence is presented for an alternative to the superoxide dismutase (SOD)-catalase oxidative stress defense system in Desulfovibrio vulgaris (strain Hildenborough). This alternative system consists of the nonheme iron proteins, rubrerythrin (Rbr) and rubredoxin oxidoreductase (Rbo), the product of the rbo gene (also called desulfoferrodoxin). A Deltarbo strain of D. vulgaris was found to be more sensitive to internal superoxide exposure than was the wild type. Unlike Rbo, expression of plasmid-borne Rbr failed to restore the aerobic growth of a SOD-deficient strain of Escherichia coli. Conversely, plasmid-borne expression of two different Rbrs from D. vulgaris increased the viability of a catalase-deficient strain of E. coli that had been exposed to hydrogen peroxide whereas Rbo actually decreased the viability. A previously undescribed D. vulgaris gene was found to encode a protein having 50% sequence identity to that of E. coli Fe-SOD. This gene also encoded an extended N-terminal sequence with high homologies to export signal peptides of periplasmic redox proteins. The SOD activity of D. vulgaris is not affected by the absence of Rbo and is concentrated in the periplasmic fraction of cell extracts. These results are consistent with a superoxide reductase rather than SOD activity of Rbo and with a peroxidase activity of Rbr. A joint role for Rbo and Rbr as a novel cytoplasmic oxidative stress protection system in D. vulgaris and other anaerobic microorganisms is proposed.
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Affiliation(s)
- H L Lumppio
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, USA
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Liochev SI, Fridovich I. Copper- and zinc-containing superoxide dismutase can act as a superoxide reductase and a superoxide oxidase. J Biol Chem 2000; 275:38482-5. [PMID: 11005823 DOI: 10.1074/jbc.m007891200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The copper- and zinc-containing superoxide dismutase can catalyze the oxidation of ferrocyanide by O(2) as well as the reduction of ferricyanide by O(2). Thus, it can act as a superoxide dismutase (SOD), a superoxide reductase (SOR), and a superoxide oxidase (SOO). The human manganese-containing SOD does not exert SOR or SOO activities with ferrocyanide or ferricyanide as the redox partners. It is possible that some biological reductants can take the place of ferrocyanide and can also interact with human manganese-containing superoxide dismutase, thus making the SOR activity a reality for both SODs. The consequences of this possibility vis à vis H(2)O(2) production, the overproduction of SODs, and the role of copper- and zinc-containing superoxide dismutase mutations in causing familial amyotrophic lateral sclerosis are discussed, as well as the likelihood that the biologically effective SOD mimics, as described to date, actually function as SORs.
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Affiliation(s)
- S I Liochev
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Coulter ED, Emerson JP, Kurtz DM, Cabelli DE. Superoxide Reactivity of Rubredoxin Oxidoreductase (Desulfoferrodoxin) fromDesulfovibriovulgaris: A Pulse Radiolysis Study. J Am Chem Soc 2000. [DOI: 10.1021/ja005583r] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abreu IA, Saraiva LM, Carita J, Huber H, Stetter KO, Cabelli D, Teixeira M. Oxygen detoxification in the strict anaerobic archaeon Archaeoglobus fulgidus: superoxide scavenging by neelaredoxin. Mol Microbiol 2000; 38:322-34. [PMID: 11069658 DOI: 10.1046/j.1365-2958.2000.02121.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Archaeoglobus fulgidus is a hyperthermophilic sulphate-reducing archaeon. It has an optimum growth temperature of 83 degrees C and is described as a strict anaerobe. Its genome lacks any homologue of canonical superoxide (O2.-) dismutases. In this work, we show that neelaredoxin (Nlr) is the main O2.- scavenger in A. fulgidus, by studying both the wild-type and recombinant proteins. Nlr is a 125-amino-acid blue-coloured protein containing a single iron atom/molecule, which in the oxidized state is high spin ferric. This iron centre has a reduction potential of +230 mV at pH 7.0. Nitroblue tetrazolium-stained gel assays of cell-soluble extracts show that Nlr is the main protein from A. fulgidus which is reactive towards O2.-. Furthermore, it is shown that Nlr is able to both reduce and dismutate O2.-, thus having a bifunctional reactivity towards O2.-. Kinetic and spectroscopic studies indicate that Nlr's superoxide reductase activity may allow the cell to eliminate O2.- quickly in a NAD(P)H-dependent pathway. On the other hand, Nlr's superoxide dismutation activity will allow the cell to detoxify O2.- independently of the cell redox status. Its superoxide dismutase activity was estimated to be 59 U mg-1 by the xanthine/xanthine oxidase assay at 25 degrees C. Pulse radiolysis studies with the isolated and reduced Nlr proved unambiguously that it has superoxide dismutase activity; at pH 7.1 and 83 degrees C, the rate constant is 5 x 106 M-1 s-1. Besides the superoxide dismutase activity, soluble cell extracts of A. fulgidus also exhibit catalase and NAD(P)H/oxygen oxidoreductase activities. By putting these findings together with the entire genomic data available, a possible oxygen detoxification mechanism in A. fulgidus is discussed.
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Affiliation(s)
- I A Abreu
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
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35
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Jovanović T, Ascenso C, Hazlett KR, Sikkink R, Krebs C, Litwiller R, Benson LM, Moura I, Moura JJ, Radolf JD, Huynh BH, Naylor S, Rusnak F. Neelaredoxin, an iron-binding protein from the syphilis spirochete, Treponema pallidum, is a superoxide reductase. J Biol Chem 2000; 275:28439-48. [PMID: 10874033 DOI: 10.1074/jbc.m003314200] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Treponema pallidum, the causative agent of venereal syphilis, is a microaerophilic obligate pathogen of humans. As it disseminates hematogenously and invades a wide range of tissues, T. pallidum presumably must tolerate substantial oxidative stress. Analysis of the T. pallidum genome indicates that the syphilis spirochete lacks most of the iron-binding proteins present in many other bacterial pathogens, including the oxidative defense enzymes superoxide dismutase, catalase, and peroxidase, but does possess an orthologue (TP0823) for neelaredoxin, an enzyme of hyperthermophilic and sulfate-reducing anaerobes shown to possess superoxide reductase activity. To analyze the potential role of neelaredoxin in treponemal oxidative defense, we examined the biochemical, spectroscopic, and antioxidant properties of recombinant T. pallidum neelaredoxin. Neelaredoxin was shown to be expressed in T. pallidum by reverse transcriptase-polymerase chain reaction and Western blot analysis. Recombinant neelaredoxin is a 26-kDa alpha(2) homodimer containing, on average, 0.7 iron atoms/subunit. Mössbauer and EPR analysis of the purified protein indicates that the iron atom exists as a mononuclear center in a mixture of high spin ferrous and ferric oxidation states. The fully oxidized form, obtained by the addition of K(3)(Fe(CN)(6)), exhibits an optical spectrum with absorbances at 280, 320, and 656 nm; the last feature is responsible for the protein's blue color, which disappears upon ascorbate reduction. The fully oxidized protein has a A(280)/A(656) ratio of 10.3. Enzymatic studies revealed that T. pallidum neelaredoxin is able to catalyze a redox equilibrium between superoxide and hydrogen peroxide, a result consistent with it being a superoxide reductase. This finding, the first description of a T. pallidum iron-binding protein, indicates that the syphilis spirochete copes with oxidative stress via a primitive mechanism, which, thus far, has not been described in pathogenic bacteria.
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Affiliation(s)
- T Jovanović
- Section of Hematology Research, Department of Biochemistry and Molecular Biology, and Biomedical Mass Spectrometry and Functional Proteomics Facility, Mayo Clinic, Rochester, Minnesota 55905, USA
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36
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Lombard M, Fontecave M, Touati D, Nivière V. Reaction of the desulfoferrodoxin from Desulfoarculus baarsii with superoxide anion. Evidence for a superoxide reductase activity. J Biol Chem 2000; 275:115-21. [PMID: 10617593 DOI: 10.1074/jbc.275.1.115] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Desulfoferrodoxin is a small protein found in sulfate-reducing bacteria that contains two independent mononuclear iron centers, one ferric and one ferrous. Expression of desulfoferrodoxin from Desulfoarculus baarsii has been reported to functionally complement a superoxide dismutase deficient Escherichia coli strain. To elucidate by which mechanism desulfoferrodoxin could substitute for superoxide dismutase in E. coli, we have purified the recombinant protein and studied its reactivity toward O-(2). Desulfoferrodoxin exhibited only a weak superoxide dismutase activity (20 units mg(-1)) that could hardly account for its antioxidant properties. UV-visible and electron paramagnetic resonance spectroscopy studies revealed that the ferrous center of desulfoferrodoxin could specifically and efficiently reduce O-(2), with a rate constant of 6-7 x 10(8) M(-1) s(-1). In addition, we showed that membrane and cytoplasmic E. coli protein extracts, using NADH and NADPH as electron donors, could reduce the O-(2) oxidized form of desulfoferrodoxin. Taken together, these results strongly suggest that desulfoferrodoxin behaves as a superoxide reductase enzyme and thus provide new insights into the biological mechanisms designed for protection from oxidative stresses.
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Affiliation(s)
- M Lombard
- Laboratoire de Chimie et Biochimie des Centres Redox Biologiques, DBMS-CEA/CNRS/Université Joseph Fourier, 17 Avenue des Martyrs, 38054 Grenoble, Cedex 9, France
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37
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Jenney FE, Verhagen MF, Cui X, Adams MW. Anaerobic microbes: oxygen detoxification without superoxide dismutase. Science 1999; 286:306-9. [PMID: 10514376 DOI: 10.1126/science.286.5438.306] [Citation(s) in RCA: 275] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Superoxide reductase from the hyperthermophilic anaerobe Pyrococcus furiosus uses electrons from reduced nicotinamide adenine dinucleotide phosphate, by way of rubredoxin and an oxidoreductase, to reduce superoxide to hydrogen peroxide, which is then reduced to water by peroxidases. Unlike superoxide dismutase, the enzyme that protects aerobes from the toxic effects of oxygen, SOR does not catalyze the production of oxygen from superoxide and therefore confers a selective advantage on anaerobes. Superoxide reductase and associated proteins are catalytically active 80 degrees C below the optimum growth temperature (100 degrees C) of P. furiosus, conditions under which the organism is likely to be exposed to oxygen.
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Affiliation(s)
- F E Jenney
- Department of Biochemistry and Molecular Biology, Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602-7229, USA
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38
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Affiliation(s)
- D Lloyd
- School of Biosciences, Cardiff University, Post Office Box 915, Cardiff CF10 3TL, Wales, UK.
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Liochev SI, Benov L, Touati D, Fridovich I. Induction of the soxRS regulon of Escherichia coli by superoxide. J Biol Chem 1999; 274:9479-81. [PMID: 10092630 DOI: 10.1074/jbc.274.14.9479] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The soxRS regulon orchestrates a multifaceted defense against oxidative stress, by inducing the transcription of approximately 15 genes. The induction of this regulon by redox agents, known to mediate O-2 production, led to the view that O-2 is one signal to which it responds. However, redox cycling agents deplete cellular reductants while producing O-2, and one may question whether the regulon responds to the depletion of some cytoplasmic reductant or to O-2, or both. We demonstrate that raising [O-2] by mutational deletion of superoxide dismutases and/or by addition of paraquat, both under aerobic conditions, causes induction of a member of the soxRS regulon and that a mutational defect in soxRS eliminates that induction. This establishes that O-2, directly or indirectly, can cause induction of this defensive regulon.
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Affiliation(s)
- S I Liochev
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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40
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Romão CV, Liu MY, Le Gall J, Gomes CM, Braga V, Pacheco I, Xavier AV, Teixeira M. The superoxide dismutase activity of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 261:438-43. [PMID: 10215854 DOI: 10.1046/j.1432-1327.1999.00278.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Desulfoferrodoxin (Dfx), a small iron protein containing two mononuclear iron centres (designated centre I and II), was shown to complement superoxide dismutase (SOD) deficient mutants of Escherichia coli [Pianzzola, M.J., Soubes M. & Touati, D. (1996) J. Bacteriol. 178, 6736-6742]. Furthermore, neelaredoxin, a protein from Desulfovibrio gigas containing an iron site similar to centre II of Dfx, was recently shown to have a significant SOD activity [Silva, G., Oliveira, S., Gomes, C.M., Pacheco, I., Liu, M.Y., Xavier, A.V., Teixeira, M., Le Gall, J. & Rodrigues-Pousada, C. (1999) Eur. J. Biochem. 259, 235-243]. Thus, the SOD activity of Dfx isolated from the sulphate-reducing bacterium Desulfovibrio desulfuricans ATCC 27774 was studied. The protein exhibits a SOD activity of 70 U x mg-1, which increases approximately 2.5-fold upon incubation with cyanide. Cyanide binds specifically to Dfx centre II, yielding a low-spin iron species with g-values at 2.27 (g perpendicular) and 1.96 (g parallel). Upon reaction of fully oxidized Dfx with the superoxide generating system xanthine/xanthine oxidase, Dfx centres I and II become partially reduced, suggesting that Dfx operates by a redox cycling mechanism, similar to those proposed for other SODs. Evidence for another SOD in D. desulfuricans is also presented - this enzyme is inhibited by cyanide, and N-terminal sequence data strongly indicates that it is an analogue to Cu,Zn-SODs isolated from other sources. This is the first indication that a Cu-containing protein may be present in a sulphate-reducing bacterium.
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Affiliation(s)
- C V Romão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Partugal
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41
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Simple and Complex Iron-Sulfur Proteins in Sulfate Reducing Bacteria. ADVANCES IN INORGANIC CHEMISTRY 1999. [DOI: 10.1016/s0898-8838(08)60083-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Silva G, Oliveira S, Gomes CM, Pacheco I, Liu MY, Xavier AV, Teixeira M, Legall J, Rodrigues-pousada C. Desulfovibrio gigas neelaredoxin. A novel superoxide dismutase integrated in a putative oxygen sensory operon of an anaerobe. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 259:235-43. [PMID: 9914498 DOI: 10.1046/j.1432-1327.1999.00025.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neelaredoxin, a small non-heme blue iron protein from the sulfate-reducing bacterium Desulfovibrio gigas [Chen, L., Sharma, P., LeGall, J., Mariano, A.M., Teixeira M. and Xavier, A.V. (1994) Eur. J. Biochem. 226, 613-618] is shown to be encoded by a polycistronic unit which contains two additional open reading frames (ORF-1 and ORF-2) coding for chemotaxis-like proteins. ORF-1 has domains highly homologous with those structurally and functionally important in methyl-accepting chemotaxis proteins, including two putative transmembrane helices, potential methylation sites and the interaction domain with CheW proteins. Interestingly, ORF-2 encodes a protein having homologies with CheW proteins. Neelaredoxin is also shown to have significant superoxide dismutase activity (1200 U. mg-1), making it a novel type of iron superoxide dismutase. Analysis of genomic data shows that neelaredoxin-like putative polypeptides are present in strict anaerobic archaea, suggesting that this is a primordial superoxide dismutase. The three proteins encoded in this operon may be involved in the oxygen-sensing mechanisms of this anaerobic bacterium, indicating a possible transcriptional mechanism to sense and respond to potential stress agents.
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Affiliation(s)
- G Silva
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
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Voordouw JK, Voordouw G. Deletion of the rbo gene increases the oxygen sensitivity of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough. Appl Environ Microbiol 1998; 64:2882-7. [PMID: 9687445 PMCID: PMC106787 DOI: 10.1128/aem.64.8.2882-2887.1998] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The rbo gene of Desulfovibrio vulgaris Hildenborough encodes rubredoxin oxidoreductase (Rbo), a 14-kDa iron sulfur protein; forms an operon with the gene for rubredoxin; and is preceded by the gene for the oxygen-sensing protein DcrA. We have deleted the rbo gene from D. vulgaris with the sacB mutagenesis procedure developed previously (R. Fu and G. Voordouw, Microbiology 143:1815-1826, 1997). The absence of the rbo-gene in the resulting mutant, D. vulgaris L2, was confirmed by PCR and protein blotting with Rbo-specific polyclonal antibodies. D. vulgaris L2 grows like the wild type under anaerobic conditions. Exposure to air for 24 h caused a 100-fold drop in CFU of L2 relative to the wild type. The lag times of liquid cultures of inocula exposed to air were on average also greater for L2 than for the wild type. These results demonstrate that Rbo, which is not homologous with superoxide dismutase or catalase, acts as an oxygen defense protein in the anaerobic, sulfate-reducing bacterium D. vulgaris Hildenborough and likely also in other sulfate-reducing bacteria and anaerobic archaea in which it has been found.
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Affiliation(s)
- J K Voordouw
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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Valentine JS, Wertz DL, Lyons TJ, Liou LL, Goto JJ, Gralla EB. The dark side of dioxygen biochemistry. Curr Opin Chem Biol 1998; 2:253-62. [PMID: 9667937 DOI: 10.1016/s1367-5931(98)80067-7] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The cellular biochemistry of dioxygen is Janus-faced. The good side includes numerous enzyme-catalyzed reactions of dioxygen that occur in respiration and normal metabolism, while the dark side encompasses deleterious reactions of species derived from dioxygen that lead to damage of cellular components. These reactive oxygen species have historically been perceived almost exclusively as agents of the dark side, but it has recently become clear that they play beneficial roles as well.
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Affiliation(s)
- J S Valentine
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095-1569, USA.
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