1
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Zhang LQ, Shen YL, Ye BC, Zhou Y. Acetylation of K188 and K192 inhibits the DNA-binding ability of NarL to regulate Salmonella virulence. Appl Environ Microbiol 2023; 89:e0068523. [PMID: 37732772 PMCID: PMC10617396 DOI: 10.1128/aem.00685-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/26/2023] [Indexed: 09/22/2023] Open
Abstract
Salmonella infection significantly increases nitrate levels in the intestine, immune cells, and immune organs of the host, and it can exploit nitrate as an electron acceptor to enhance its growth. In the presence of nitrate or nitrite, NarL, a regulatory protein of the Nar two-component system, is activated and regulates a number of genes involved in nitrate metabolism. However, research on NarL at the post-translational level is limited. In this study, we demonstrate that the DNA-binding sites K188 and 192 of NarL can be acetylated by bacterial metabolite acetyl phosphate and that the degree of acetylation has a considerable influence on the regulatory function of NarL. Specifically, acetylation of NarL negatively regulates the transcription of narG, narK, and napF, which affects the utilization of nitrate in Salmonella. Besides, both cell and mouse models show that acetylated K188 and K192 result in attenuated replication in RAW 264.7 cells, as well as impaired virulence in mouse model. Together, this research identifies a novel NarL acetylation mechanism that regulates Salmonella virulence, providing a new insight and target for salmonellosis treatment.IMPORTANCESalmonella is an important intracellular pathogen that can cause limited gastroenteritis and self-limiting gastroenteritis in immunocompetent humans. Nitrate, the highest oxidation state form of nitrogen, is critical in the formation of systemic infection in Salmonella. It functions as a signaling molecule that influences Salmonella chemotaxis, in addition to acting as a reduced external electron acceptor for Salmonella anaerobic respiration. NarL is an essential regulatory protein involved in nitrate metabolism in Salmonella, and comprehending its regulatory mechanism is necessary. Previous research has linked NarL phosphorylation to the formation of its dimer, which is required for NarL to perform its regulatory functions. Our research demonstrated that acetylation also affects the regulatory function of NarL. We found that acetylation affects Salmonella pathogenicity by weakening the ability of NarL to bind to the target sequence, further refining the mechanism of the anaerobic nitrate respiration pathway.
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Affiliation(s)
- Liu-Qing Zhang
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yi-Lin Shen
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Bang-Ce Ye
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Ying Zhou
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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2
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Rixen S, Indorf PM, Kubitza C, Struwe MA, Klopp C, Scheidig AJ, Kunze T, Clement B. Reduction of Hydrogen Peroxide by Human Mitochondrial Amidoxime Reducing Component Enzymes. Molecules 2023; 28:6384. [PMID: 37687214 PMCID: PMC10489706 DOI: 10.3390/molecules28176384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/23/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
The mitochondrial amidoxime reducing component (mARC) is a human molybdoenzyme known to catalyze the reduction of various N-oxygenated substrates. The physiological function of mARC enzymes, however, remains unknown. In this study, we examine the reduction of hydrogen peroxide (H2O2) by the human mARC1 and mARC2 enzymes. Furthermore, we demonstrate an increased sensitivity toward H2O2 for HEK-293T cells with an MTARC1 knockout, which implies a role of mARC enzymes in the cellular response to oxidative stress. H2O2 is a reactive oxygen species (ROS) formed in all living cells involved in many physiological processes. Furthermore, H2O2 constitutes the first mARC substrate without a nitrogen-oxygen bond, implying that mARC enzymes may have a substrate spectrum going beyond the previously examined N-oxygenated compounds.
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Affiliation(s)
- Sophia Rixen
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Patrick M. Indorf
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Christian Kubitza
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Michel A. Struwe
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Cathrin Klopp
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Axel J. Scheidig
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Thomas Kunze
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Bernd Clement
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
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3
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Moco Carrier and Binding Proteins. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27196571. [PMID: 36235107 PMCID: PMC9571131 DOI: 10.3390/molecules27196571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/25/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022]
Abstract
The molybdenum cofactor (Moco) is the active site prosthetic group found in numerous vitally important enzymes (Mo-enzymes), which predominantly catalyze 2 electron transfer reactions. Moco is synthesized by an evolutionary old and highly conserved multi-step pathway, whereby the metal insertion reaction is the ultimate reaction step here. Moco and its intermediates are highly sensitive towards oxidative damage and considering this, they are believed to be permanently protein bound during synthesis and also after Moco maturation. In plants, a cellular Moco transfer and storage system was identified, which comprises proteins that are capable of Moco binding and release but do not possess a Moco-dependent enzymatic activity. The first protein described that exhibited these properties was the Moco carrier protein (MCP) from the green alga Chlamydomonas reinhardtii. However, MCPs and similar proteins have meanwhile been described in various plant species. This review will summarize the current knowledge of the cellular Moco distribution system.
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4
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Kruse T. Function of Molybdenum Insertases. Molecules 2022; 27:molecules27175372. [PMID: 36080140 PMCID: PMC9458074 DOI: 10.3390/molecules27175372] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/11/2022] [Accepted: 08/17/2022] [Indexed: 11/16/2022] Open
Abstract
For most organisms molybdenum is essential for life as it is found in the active site of various vitally important molybdenum dependent enzymes (Mo-enzymes). Here, molybdenum is bound to a pterin derivative called molybdopterin (MPT), thus forming the molybdenum cofactor (Moco). Synthesis of Moco involves the consecutive action of numerous enzymatic reaction steps, whereby molybdenum insertases (Mo-insertases) catalyze the final maturation step, i.e., the metal insertion reaction yielding Moco. This final maturation step is subdivided into two partial reactions, each catalyzed by a distinctive Mo-insertase domain. Initially, MPT is adenylylated by the Mo-insertase G-domain, yielding MPT-AMP which is used as substrate by the E-domain. This domain catalyzes the insertion of molybdate into the MPT dithiolene moiety, leading to the formation of Moco-AMP. Finally, the Moco-AMP phosphoanhydride bond is cleaved by the E-domain to liberate Moco from its synthesizing enzyme. Thus formed, Moco is physiologically active and may be incorporated into the different Mo-enzymes or bind to carrier proteins instead.
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Affiliation(s)
- Tobias Kruse
- Institute of Plant Biology, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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5
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Mendel RR. The History of the Molybdenum Cofactor-A Personal View. Molecules 2022; 27:4934. [PMID: 35956883 PMCID: PMC9370521 DOI: 10.3390/molecules27154934] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 11/16/2022] Open
Abstract
The transition element molybdenum (Mo) is an essential micronutrient for plants, animals, and microorganisms, where it forms part of the active center of Mo enzymes. To gain biological activity in the cell, Mo has to be complexed by a pterin scaffold to form the molybdenum cofactor (Moco). Mo enzymes and Moco are found in all kingdoms of life, where they perform vital transformations in the metabolism of nitrogen, sulfur, and carbon compounds. In this review, I recall the history of Moco in a personal view, starting with the genetics of Moco in the 1960s and 1970s, followed by Moco biochemistry and the description of its chemical structure in the 1980s. When I review the elucidation of Moco biosynthesis in the 1990s and the early 2000s, I do it mainly for eukaryotes, as I worked with plants, human cells, and filamentous fungi. Finally, I briefly touch upon human Moco deficiency and whether there is life without Moco.
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Affiliation(s)
- Ralf R Mendel
- Institute of Plant Biology, Technical University Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany
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6
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Crack JC, Balasiny BK, Bennett SP, Rolfe MD, Froes A, MacMillan F, Green J, Cole JA, Le Brun NE. The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress. J Am Chem Soc 2022; 144:7129-7145. [PMID: 35416044 PMCID: PMC9052748 DOI: 10.1021/jacs.1c12407] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Indexed: 01/09/2023]
Abstract
Previously characterized nitrite reductases fall into three classes: siroheme-containing enzymes (NirBD), cytochrome c hemoproteins (NrfA and NirS), and copper-containing enzymes (NirK). We show here that the di-iron protein YtfE represents a physiologically relevant new class of nitrite reductases. Several functions have been previously proposed for YtfE, including donating iron for the repair of iron-sulfur clusters that have been damaged by nitrosative stress, releasing nitric oxide (NO) from nitrosylated iron, and reducing NO to nitrous oxide (N2O). Here, in vivo reporter assays confirmed that Escherichia coli YtfE increased cytoplasmic NO production from nitrite. Spectroscopic and mass spectrometric investigations revealed that the di-iron site of YtfE exists in a mixture of forms, including nitrosylated and nitrite-bound, when isolated from nitrite-supplemented, but not nitrate-supplemented, cultures. Addition of nitrite to di-ferrous YtfE resulted in nitrosylated YtfE and the release of NO. Kinetics of nitrite reduction were dependent on the nature of the reductant; the lowest Km, measured for the di-ferrous form, was ∼90 μM, well within the intracellular nitrite concentration range. The vicinal di-cysteine motif, located in the N-terminal domain of YtfE, was shown to function in the delivery of electrons to the di-iron center. Notably, YtfE exhibited very low NO reductase activity and was only able to act as an iron donor for reconstitution of apo-ferredoxin under conditions that damaged its di-iron center. Thus, YtfE is a high-affinity, low-capacity nitrite reductase that we propose functions to relieve nitrosative stress by acting in combination with the co-regulated NO-consuming enzymes Hmp and Hcp.
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Affiliation(s)
- Jason C. Crack
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Basema K. Balasiny
- Institute
of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Sophie P. Bennett
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Matthew D. Rolfe
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Afonso Froes
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Fraser MacMillan
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Jeffrey Green
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Jeffrey A. Cole
- Institute
of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Nick E. Le Brun
- Centre
for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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7
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Gushchin I, Aleksenko VA, Orekhov P, Goncharov IM, Nazarenko VV, Semenov O, Remeeva A, Gordeliy V. Nitrate- and Nitrite-Sensing Histidine Kinases: Function, Structure, and Natural Diversity. Int J Mol Sci 2021; 22:5933. [PMID: 34072989 PMCID: PMC8199190 DOI: 10.3390/ijms22115933] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 12/18/2022] Open
Abstract
Under anaerobic conditions, bacteria may utilize nitrates and nitrites as electron acceptors. Sensitivity to nitrous compounds is achieved via several mechanisms, some of which rely on sensor histidine kinases (HKs). The best studied nitrate- and nitrite-sensing HKs (NSHKs) are NarQ and NarX from Escherichia coli. Here, we review the function of NSHKs, analyze their natural diversity, and describe the available structural information. In particular, we show that around 6000 different NSHK sequences forming several distinct clusters may now be found in genomic databases, comprising mostly the genes from Beta- and Gammaproteobacteria as well as from Bacteroidetes and Chloroflexi, including those from anaerobic ammonia oxidation (annamox) communities. We show that the architecture of NSHKs is mostly conserved, although proteins from Bacteroidetes lack the HAMP and GAF-like domains yet sometimes have PAS. We reconcile the variation of NSHK sequences with atomistic models and pinpoint the structural elements important for signal transduction from the sensor domain to the catalytic module over the transmembrane and cytoplasmic regions spanning more than 200 Å.
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Affiliation(s)
- Ivan Gushchin
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
| | - Vladimir A. Aleksenko
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
| | - Philipp Orekhov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
- Faculty of Biology, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Ivan M. Goncharov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
| | - Vera V. Nazarenko
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
| | - Oleg Semenov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
| | - Alina Remeeva
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
| | - Valentin Gordeliy
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia; (V.A.A.); (P.O.); (I.M.G.); (V.V.N.); (O.S.); (A.R.)
- Institut de Biologie Structurale J.-P. Ebel, Université Grenoble Alpes-CEA-CNRS, 38000 Grenoble, France
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52428 Jülich, Germany
- JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52428 Jülich, Germany
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8
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Warnhoff K, Hercher TW, Mendel RR, Ruvkun G. Protein-bound molybdenum cofactor is bioavailable and rescues molybdenum cofactor-deficient C. elegans. Genes Dev 2021; 35:212-217. [PMID: 33446569 PMCID: PMC7849362 DOI: 10.1101/gad.345579.120] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/01/2020] [Indexed: 01/10/2023]
Abstract
In this paper, Warnoff et al. investigated the mechanism by which C. elegans stably acquires molybdenum cofactor (Moco), which is essential in animals and causes lethal neurological and developmental defects in humans with mutations in genes that encode Moco biosynthetic enzymes. The authors show that protein-bound Moco is the stable, bioavailable species of Moco taken up by C. elegans from its diet and is an effective dietary supplement in a C. elegans model of Moco deficiency, and that these Moco:protein complexes are very stable, suggesting they may provide a strategy for the production and delivery of therapeutically active Moco to treat human Moco deficiency. The molybdenum cofactor (Moco) is a 520-Da prosthetic group that is synthesized in all domains of life. In animals, four oxidases (among them sulfite oxidase) use Moco as a prosthetic group. Moco is essential in animals; humans with mutations in genes that encode Moco biosynthetic enzymes display lethal neurological and developmental defects. Moco supplementation seems a logical therapy; however, the instability of Moco has precluded biochemical and cell biological studies of Moco transport and bioavailability. The nematode Caenorhabditis elegans can take up Moco from its bacterial diet and transport it to cells and tissues that express Moco-requiring enzymes, suggesting a system for Moco uptake and distribution. Here we show that protein-bound Moco is the stable, bioavailable species of Moco taken up by C. elegans from its diet and is an effective dietary supplement, rescuing a C. elegans model of Moco deficiency. We demonstrate that diverse Moco:protein complexes are stable and bioavailable, suggesting a new strategy for the production and delivery of therapeutically active Moco to treat human Moco deficiency.
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Affiliation(s)
- Kurt Warnhoff
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Thomas W Hercher
- Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Ralf R Mendel
- Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
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9
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Hercher T, Krausze J, Yang J, Kirk M, Kruse T. Identification and characterisation of the Volvox carteri Moco carrier protein. Biosci Rep 2020; 40:BSR20202351. [PMID: 33084886 PMCID: PMC7687042 DOI: 10.1042/bsr20202351] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/08/2020] [Accepted: 10/13/2020] [Indexed: 11/23/2022] Open
Abstract
The molybdenum cofactor (Moco) is a redox active prosthetic group found in the active site of Moco-dependent enzymes (Mo-enzymes). As Moco and its intermediates are highly sensitive towards oxidative damage, these are believed to be permanently protein bound during synthesis and upon maturation. As a major component of the plant Moco transfer and storage system, proteins have been identified that are capable of Moco binding and release but do not possess Moco-dependent enzymatic activities. The first protein found to possess these properties was the Moco carrier protein (MCP) from the green alga Chlamydomonas reinhardtii. Here, we describe the identification and biochemical characterisation of the Volvox carteri (V. carteri) MCP and, for the first time, employ a comparative analysis to elucidate the principles behind MCP Moco binding. Doing so identified a sequence region of low homology amongst the existing MCPs, which we showed to be essential for Moco binding to V. carteri MCP.
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Affiliation(s)
- Thomas W. Hercher
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Joern Krausze
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001, U.S.A
| | - Martin L. Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001, U.S.A
| | - Tobias Kruse
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
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10
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Hercher TW, Krausze J, Hoffmeister S, Zwerschke D, Lindel T, Blankenfeldt W, Mendel RR, Kruse T. Insights into the Cnx1E catalyzed MPT-AMP hydrolysis. Biosci Rep 2020; 40:BSR20191806. [PMID: 31860061 PMCID: PMC6954367 DOI: 10.1042/bsr20191806] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 11/23/2022] Open
Abstract
Molybdenum insertases (Mo-insertases) catalyze the final step of molybdenum cofactor (Moco) biosynthesis, an evolutionary old and highly conserved multi-step pathway. In the first step of the pathway, GTP serves as substrate for the formation of cyclic pyranopterin monophosphate, which is subsequently converted into molybdopterin (MPT) in the second pathway step. In the following synthesis steps, MPT is adenylated yielding MPT-AMP that is subsequently used as substrate for enzyme catalyzed molybdate insertion. Molybdate insertion and MPT-AMP hydrolysis are catalyzed by the Mo-insertase E-domain. Earlier work reported a highly conserved aspartate residue to be essential for Mo-insertase functionality. In this work, we confirmed the mechanistic relevance of this residue for the Arabidopsis thaliana Mo-insertase Cnx1E. We found that the conservative substitution of Cnx1E residue Asp274 by Glu (D274E) leads to an arrest of MPT-AMP hydrolysis and hence to the accumulation of MPT-AMP. We further showed that the MPT-AMP accumulation goes in hand with the accumulation of molybdate. By crystallization and structure determination of the Cnx1E variant D274E, we identified the potential reason for the missing hydrolysis activity in the disorder of the region spanning amino acids 269 to 274. We reasoned that this is caused by the inability of a glutamate in position 274 to coordinate the octahedral Mg2+-water complex in the Cnx1E active site.
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Affiliation(s)
- Thomas W. Hercher
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Joern Krausze
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Sven Hoffmeister
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Dagmar Zwerschke
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Thomas Lindel
- TU Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany
| | - Wulf Blankenfeldt
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
- TU Braunschweig, Department for Biotechnology, Institute of Biochemistry, Biotechnology and Bioinformatics, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Ralf R. Mendel
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Tobias Kruse
- TU Braunschweig, Institute of Plant Biology, Spielmannstrasse 7, 38106 Braunschweig, Germany
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11
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Kaufmann P, Iobbi-Nivol C, Leimkühler S. Reconstitution of Molybdoenzymes with Bis-Molybdopterin Guanine Dinucleotide Cofactors. Methods Mol Biol 2019; 1876:141-152. [PMID: 30317479 DOI: 10.1007/978-1-4939-8864-8_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Molybdoenzymes are ubiquitous and play important roles in all kingdoms of life. The cofactors of these enzymes comprise the metal, molybdenum (Mo), which is bound to a special organic ligand system called molybdopterin (MPT). Additional small ligands are present at the Mo atom, including water, hydroxide, oxo-, sulfido-, or selenido-functionalities, and in some enzymes, amino acid ligand, such as serine, aspartate, cysteine, or selenocysteine that coordinate the cofactor to the peptide chain of the enzyme. The so-called molybdenum cofactor (Moco) is deeply buried within the protein at the end of a narrow funnel, giving access only to the substrate. In 1974, an assay was developed by Nason and coworkers using the pleiotropic Neurospora crassa mutant, nit-1, for the reconstitution of molybdoenzyme activities from crude extracts. These studies have led to the understanding that Moco is the common element in all molybdoenzymes from different organisms. The assay has been further developed since then by using specific molybdenum enzymes as the source of Moco for the reconstitution of diverse purified apo-molybdoenzymes. Alternatively, the molybdenum cofactor can be synthesized in vitro from stable intermediates and subsequently inserted into apo-molybdoenzymes with the assistance of specific Moco-binding chaperones. A general working protocol is described here for the insertion of the bis-molybdopterin guanine dinucleotide cofactor (bis-MGD) into its target molybdoenzyme using the example of Escherichia coli trimethylamine N-oxide (TMAO) reductase.
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Affiliation(s)
- Paul Kaufmann
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | | | - Silke Leimkühler
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
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12
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Bender D, Kaczmarek AT, Santamaria-Araujo JA, Stueve B, Waltz S, Bartsch D, Kurian L, Cirak S, Schwarz G. Impaired mitochondrial maturation of sulfite oxidase in a patient with severe sulfite oxidase deficiency. Hum Mol Genet 2019; 28:2885-2899. [DOI: 10.1093/hmg/ddz109] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/09/2019] [Accepted: 05/07/2019] [Indexed: 01/24/2023] Open
Abstract
AbstractSulfite oxidase (SO) is encoded by the nuclear SUOX gene and catalyzes the final step in cysteine catabolism thereby oxidizing sulfite to sulfate. Oxidation of sulfite is dependent on two cofactors within SO, a heme and the molybdenum cofactor (Moco), the latter forming the catalytic site of sulfite oxidation. SO localizes to the intermembrane space of mitochondria where both—pre-SO processing and cofactor insertion—are essential steps during SO maturation. Isolated SO deficiency (iSOD) is a rare inborn error of metabolism caused by mutations in the SUOX gene that lead to non-functional SO. ISOD is characterized by rapidly progressive neurodegeneration and death in early infancy. We diagnosed an iSOD patient with homozygous mutation of SUOX at c.1084G>A replacing Gly362 to serine. To understand the mechanism of disease, we expressed patient-derived G362S SO in Escherichia coli and surprisingly found full catalytic activity, while in patient fibroblasts no SO activity was detected, suggesting differences between bacterial and human expression. Moco reconstitution of apo-G362S SO was found to be approximately 90-fold reduced in comparison to apo-WT SO in vitro. In line, levels of SO-bound Moco in cells overexpressing G362S SO were significantly reduced compared to cells expressing WT SO providing evidence for compromised maturation of G362S SO in cellulo. Addition of molybdate to culture medium partially rescued impaired Moco binding of G362S SO and restored SO activity in patient fibroblasts. Thus, this study demonstrates the importance of the orchestrated maturation of SO and provides a first case of Moco-responsive iSOD.
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Affiliation(s)
- Daniel Bender
- Department of Chemistry, Institute for Biochemistry, University of Cologne, 50674 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne Germany
| | - Alexander Tobias Kaczmarek
- Department of Chemistry, Institute for Biochemistry, University of Cologne, 50674 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne Germany
| | | | - Burkard Stueve
- Abteilung für Kinderneurologie, Epileptologie und Sozialpädiatrie, Kliniken Köln, Kinderkrankenhaus, 51058 Cologne, Germany
| | - Stephan Waltz
- Abteilung für Kinderneurologie, Epileptologie und Sozialpädiatrie, Kliniken Köln, Kinderkrankenhaus, 51058 Cologne, Germany
| | - Deniz Bartsch
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne Germany
| | - Leo Kurian
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne Germany
| | - Sebahattin Cirak
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne Germany
- Klinik für Kinderheilkunde und Jugendmedizin, Uniklinikum Köln, 50937 Cologne, Germany
| | - Guenter Schwarz
- Department of Chemistry, Institute for Biochemistry, University of Cologne, 50674 Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne Germany
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Soil HONO emissions at high moisture content are driven by microbial nitrate reduction to nitrite: tackling the HONO puzzle. ISME JOURNAL 2019; 13:1688-1699. [PMID: 30833686 DOI: 10.1038/s41396-019-0379-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 02/08/2019] [Indexed: 11/08/2022]
Abstract
Nitrous acid (HONO) is a precursor of the hydroxyl radical (OH), a key oxidant in the degradation of most air pollutants. Field measurements indicate a large unknown source of HONO during the day time. Release of nitrous acid (HONO) from soil has been suggested as a major source of atmospheric HONO. We hypothesize that nitrite produced by biological nitrate reduction in oxygen-limited microzones in wet soils is a source of such HONO. Indeed, we found that various contrasting soil samples emitted HONO at high water-holding capacity (75-140%), demonstrating this to be a widespread phenomenon. Supplemental nitrate stimulated HONO emissions, whereas ethanol (70% v/v) treatment to minimize microbial activities reduced HONO emissions by 80%, suggesting that nitrate-dependent biotic processes are the sources of HONO. High-throughput Illumina sequencing of 16S rRNA as well as functional gene transcripts associated with nitrate and nitrite reduction indicated that HONO emissions from soil samples were associated with nitrate reduction activities of diverse Proteobacteria. Incubation of pure cultures of bacterial nitrate reducers and gene-expression analyses, as well as the analyses of mutant strains deficient in nitrite reductases, showed positive correlations of HONO emissions with the capability of microbes to reduce nitrate to nitrite. Thus, we suggest biological nitrate reduction in oxygen-limited microzones as a hitherto unknown source of atmospheric HONO, affecting biogeochemical nitrogen cycling, atmospheric chemistry, and global modeling.
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Zupok A, Iobbi-Nivol C, Méjean V, Leimkühler S. The regulation of Moco biosynthesis and molybdoenzyme gene expression by molybdenum and iron in bacteria. Metallomics 2019; 11:1602-1624. [DOI: 10.1039/c9mt00186g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The regulation of the operons involved in Moco biosynthesis is dependent on the availability of Fe–S clusters in the cell.
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Affiliation(s)
- Arkadiusz Zupok
- University of Potsdam
- Institute of Biochemistry and Biology
- Molecular Enzymology
- Potsdam-Golm
- Germany
| | - Chantal Iobbi-Nivol
- Aix-Marseille Université
- Institut de Microbiologie de la Méditerranée
- Laboratoire de Bioénergétique et Ingénierie des Protéines
- Centre National de la Recherche Scientifique
- Marseille
| | - Vincent Méjean
- Aix-Marseille Université
- Institut de Microbiologie de la Méditerranée
- Laboratoire de Bioénergétique et Ingénierie des Protéines
- Centre National de la Recherche Scientifique
- Marseille
| | - Silke Leimkühler
- University of Potsdam
- Institute of Biochemistry and Biology
- Molecular Enzymology
- Potsdam-Golm
- Germany
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15
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Schwanhold N, Iobbi-Nivol C, Lehmann A, Leimkühler S. Same but different: Comparison of two system-specific molecular chaperones for the maturation of formate dehydrogenases. PLoS One 2018; 13:e0201935. [PMID: 30444874 PMCID: PMC6239281 DOI: 10.1371/journal.pone.0201935] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 08/21/2018] [Indexed: 11/19/2022] Open
Abstract
The maturation of bacterial molybdoenzymes is a complex process leading to the insertion of the bulky bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor into the apo-enzyme. Most molybdoenzymes were shown to contain a specific chaperone for the insertion of the bis-MGD cofactor. Formate dehydrogenases (FDH) together with their molecular chaperone partner seem to display an exception to this specificity rule, since the chaperone FdhD has been proven to be involved in the maturation of all three FDH enzymes present in Escherichia coli. Multiple roles have been suggested for FdhD-like chaperones in the past, including the involvement in a sulfur transfer reaction from the l-cysteine desulfurase IscS to bis-MGD by the action of two cysteine residues present in a conserved CXXC motif of the chaperones. However, in this study we show by phylogenetic analyses that the CXXC motif is not conserved among FdhD-like chaperones. We compared in detail the FdhD-like homologues from Rhodobacter capsulatus and E. coli and show that their roles in the maturation of FDH enzymes from different subgroups can be exchanged. We reveal that bis-MGD-binding is a common characteristic of FdhD-like proteins and that the cofactor is bound with a sulfido-ligand at the molybdenum atom to the chaperone. Generally, we reveal that the cysteine residues in the motif CXXC of the chaperone are not essential for the production of active FDH enzymes.
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Affiliation(s)
- Nadine Schwanhold
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | | | - Angelika Lehmann
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | - Silke Leimkühler
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
- * E-mail:
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16
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The functional principle of eukaryotic molybdenum insertases. Biochem J 2018; 475:1739-1753. [PMID: 29717023 DOI: 10.1042/bcj20170935] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/23/2018] [Accepted: 05/01/2018] [Indexed: 02/06/2023]
Abstract
The molybdenum cofactor (Moco) is a redox-active prosthetic group found in the active site of Moco-dependent enzymes, which are vitally important for life. Moco biosynthesis involves several enzymes that catalyze the subsequent conversion of GTP into cyclic pyranopterin monophosphate (cPMP), molybdopterin (MPT), adenylated MPT (MPT-AMP), and finally Moco. While the underlying principles of cPMP, MPT, and MPT-AMP formation are well understood, the molybdenum insertase (Mo-insertase)-catalyzed final Moco maturation step is not. In the present study, we analyzed high-resolution X-ray datasets of the plant Mo-insertase Cnx1E that revealed two molybdate-binding sites within the active site, hence improving the current view on Cnx1E functionality. The presence of molybdate anions in either of these sites is tied to a distinctive backbone conformation, which we suggest to be essential for Mo-insertase molybdate selectivity and insertion efficiency.
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Kaufmann P, Duffus BR, Teutloff C, Leimkühler S. Functional Studies on Oligotropha carboxidovorans Molybdenum–Copper CO Dehydrogenase Produced in Escherichia coli. Biochemistry 2018; 57:2889-2901. [DOI: 10.1021/acs.biochem.8b00128] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Paul Kaufmann
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, 14476 Potsdam, Germany
| | - Benjamin R. Duffus
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, 14476 Potsdam, Germany
| | - Christian Teutloff
- Institute for Experimental Physics, Free University of Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Silke Leimkühler
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, 14476 Potsdam, Germany
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18
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Balasiny B, Rolfe MD, Vine C, Bradley C, Green J, Cole J. Release of nitric oxide by the Escherichia coli YtfE (RIC) protein and its reduction by the hybrid cluster protein in an integrated pathway to minimize cytoplasmic nitrosative stress. Microbiology (Reading) 2018; 164:563-575. [DOI: 10.1099/mic.0.000629] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Basema Balasiny
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Matthew D. Rolfe
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Claire Vine
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Charlene Bradley
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Jeffrey Green
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Jeff Cole
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
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19
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Chen Z, Huang Z, He Y, Xiao X, Wei Z. Effect of UV on De-NOxperformance and microbial community of a hybrid catalytic membrane biofilm reactor. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1755-1315/121/3/032024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Dimerization of the plant molybdenum insertase Cnx1E is required for synthesis of the molybdenum cofactor. Biochem J 2016; 474:163-178. [PMID: 27803248 DOI: 10.1042/bcj20160846] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/24/2016] [Accepted: 10/28/2016] [Indexed: 11/17/2022]
Abstract
The molybdenum cofactor (Moco) is a redox active prosthetic group, essentially required for numerous enzyme-catalyzed two electron transfer reactions. Moco is synthesized by an evolutionarily old and highly conserved multistep pathway. In the last step of Moco biosynthesis, the molybdenum center is inserted into the final Moco precursor adenylated molybdopterin (MPT-AMP). This unique and yet poorly characterized maturation reaction finally yields physiologically active Moco. In the model plant Arabidopsis, the two domain enzyme, Cnx1, is required for Moco formation. Recently, a genetic screen identified novel Arabidopsis cnx1 mutant plant lines each harboring a single amino acid exchange in the N-terminal Cnx1E domain. Biochemical characterization of the respective recombinant Cnx1E variants revealed two different amino acid exchanges (S197F and G175D) that impair Cnx1E dimerization, thus linking Cnx1E oligomerization to Cnx1 functionality. Analysis of the Cnx1E structure identified Cnx1E active site-bound molybdate and magnesium ions, which allowed to fine-map the Cnx1E MPT-AMP-binding site.
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21
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Wang J, Vine CE, Balasiny BK, Rizk J, Bradley CL, Tinajero-Trejo M, Poole RK, Bergaust LL, Bakken LR, Cole JA. The roles of the hybrid cluster protein, Hcp and its reductase, Hcr, in high affinity nitric oxide reduction that protects anaerobic cultures ofEscherichia coliagainst nitrosative stress. Mol Microbiol 2016; 100:877-92. [DOI: 10.1111/mmi.13356] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Jing Wang
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Claire E. Vine
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Basema K. Balasiny
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - John Rizk
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Charlene L. Bradley
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Mariana Tinajero-Trejo
- Department of Molecular Biology & Biotechnology; University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | - Robert K. Poole
- Department of Molecular Biology & Biotechnology; University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | | | - Lars R. Bakken
- Norwegian University of Life Science; PO box 5003 N-1432 Ås Norway
| | - Jeffrey A. Cole
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
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22
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Abstract
The transition element molybdenum (Mo) is of primordial importance for biological systems as it is required by enzymes catalyzing key reactions in global carbon, sulfur, and nitrogen metabolism. In order to gain biological activity, Mo has to be complexed by a special cofactor. With the exception of bacterial nitrogenase, all Mo-dependent enzymes contain a unique pyranopterin-based cofactor coordinating a Mo atom at their catalytic site. Various types of reactions are catalyzed by Mo enzymes in prokaryotes, including oxygen atom transfer, sulfur or proton transfer, hydroxylation, or even nonredox ones. Mo enzymes are widespread in prokaryotes, and many of them were likely present in LUCA. To date, more than 50-mostly bacterial-Mo enzymes are described in nature. In a few eubacteria and in many archaea, Mo is replaced by tungsten bound to the same unique pyranopterin. How Moco is synthesized in bacteria is reviewed as well as the way until its insertion into apo-Mo-enzymes.
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23
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Structural basis for dynamic mechanism of nitrate/nitrite antiport by NarK. Nat Commun 2015; 6:7097. [PMID: 25959928 PMCID: PMC4432589 DOI: 10.1038/ncomms8097] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 04/03/2015] [Indexed: 01/21/2023] Open
Abstract
NarK belongs to the nitrate/nitrite porter (NNP) family in the major facilitator superfamily (MFS) and plays a central role in nitrate uptake across the membrane in diverse organisms, including archaea, bacteria, fungi and plants. Although previous studies provided insight into the overall structure and the substrate recognition of NarK, its molecular mechanism, including the driving force for nitrate transport, remained elusive. Here we demonstrate that NarK is a nitrate/nitrite antiporter, using an in vitro reconstituted system. Furthermore, we present the high-resolution crystal structures of NarK from Escherichia coli in the nitrate-bound occluded, nitrate-bound inward-open and apo inward-open states. The integrated structural, functional and computational analyses reveal the nitrate/nitrite antiport mechanism of NarK, in which substrate recognition is coupled to the transport cycle by the concomitant movement of the transmembrane helices and the key tyrosine and arginine residues in the substrate-binding site. Nitrate/nitrite porters (NNP) play a central role in nitrate uptake in archaea, bacteria, fungi and plants. Here, Fukuda et al. use a liposome-based transport assay, X-ray crystallography and molecular dynamics simulation to reveal the dynamic nitrate/nitrite antiport mechanism of a bacterial NNP, NarK.
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Ringel P, Probst C, Dammeyer T, Buchmeier S, Jänsch L, Wissing J, Tinnefeld P, Mendel RR, Jockusch BM, Kruse T. Enzymatic characterization of recombinant nitrate reductase expressed and purified from Neurospora crassa. Fungal Genet Biol 2015; 80:10-8. [PMID: 25914160 DOI: 10.1016/j.fgb.2015.04.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 04/13/2015] [Indexed: 01/14/2023]
Abstract
We established an expression and purification procedure for recombinant protein production in Neurospora crassa (N. crassa). This Strep-tag® based system was successfully used for purifying recombinant N. crassa nitrate reductase (NR), whose enzymatic activity was compared to recombinant N. crassa NR purified from Escherichia coli. The purity of the two different NR preparations was similar but NR purified from N. crassa showed a significantly higher nitrate turnover rate. Two phosphorylation sites were identified for NR purified from the endogenous expression system. We conclude that homologous expression of N. crassa NR yields a higher active enzyme and propose that NR phosphorylation causes enhanced enzymatic activity.
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Affiliation(s)
- Phillip Ringel
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Corinna Probst
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Thorben Dammeyer
- Department of Physical and Theoretical Chemistry and Braunschweig Integrated Center of Systems Biology (BRICS), Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Sabine Buchmeier
- Department of Physical and Theoretical Chemistry and Braunschweig Integrated Center of Systems Biology (BRICS), Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Lothar Jänsch
- Cellular Proteomics, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Josef Wissing
- Cellular Proteomics, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Philip Tinnefeld
- Department of Physical and Theoretical Chemistry and Braunschweig Integrated Center of Systems Biology (BRICS), Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Ralf R Mendel
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Brigitte M Jockusch
- Zoological Institute, Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Tobias Kruse
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany.
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25
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Abstract
The transition element molybdenum (Mo) is of primordial importance for biological systems, because it is required by enzymes catalyzing key reactions in the global carbon, sulfur, and nitrogen metabolism. To gain biological activity, Mo has to be complexed by a special cofactor. With the exception of bacterial nitrogenase, all Mo-dependent enzymes contain a unique pyranopterin-based cofactor coordinating a Mo atom at their catalytic site. Various types of reactions are catalyzed by Mo-enzymes in prokaryotes including oxygen atom transfer, sulfur or proton transfer, hydroxylation, or even nonredox reactions. Mo-enzymes are widespread in prokaryotes and many of them were likely present in the Last Universal Common Ancestor. To date, more than 50--mostly bacterial--Mo-enzymes are described in nature. In a few eubacteria and in many archaea, Mo is replaced by tungsten bound to the same unique pyranopterin. How Mo-cofactor is synthesized in bacteria is reviewed as well as the way until its insertion into apo-Mo-enzymes.
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26
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Carlson HK, Kuehl JV, Hazra AB, Justice NB, Stoeva MK, Sczesnak A, Mullan MR, Iavarone AT, Engelbrektson A, Price MN, Deutschbauer AM, Arkin AP, Coates JD. Mechanisms of direct inhibition of the respiratory sulfate-reduction pathway by (per)chlorate and nitrate. ISME JOURNAL 2014; 9:1295-305. [PMID: 25405978 DOI: 10.1038/ismej.2014.216] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 09/30/2014] [Accepted: 10/04/2014] [Indexed: 12/26/2022]
Abstract
We investigated perchlorate (ClO(4)(-)) and chlorate (ClO(3)(-)) (collectively (per)chlorate) in comparison with nitrate as potential inhibitors of sulfide (H(2)S) production by mesophilic sulfate-reducing microorganisms (SRMs). We demonstrate the specificity and potency of (per)chlorate as direct SRM inhibitors in both pure cultures and undefined sulfidogenic communities. We demonstrate that (per)chlorate and nitrate are antagonistic inhibitors and resistance is cross-inducible implying that these compounds share at least one common mechanism of resistance. Using tagged-transposon pools we identified genes responsible for sensitivity and resistance in Desulfovibrio alaskensis G20. We found that mutants in Dde_2702 (Rex), a repressor of the central sulfate-reduction pathway were resistant to both (per)chlorate and nitrate. In general, Rex derepresses its regulon in response to increasing intracellular NADH:NAD(+) ratios. In cells in which respiratory sulfate reduction is inhibited, NADH:NAD(+) ratios should increase leading to derepression of the sulfate-reduction pathway. In support of this, in (per)chlorate or nitrate-stressed wild-type G20 we observed higher NADH:NAD(+) ratios, increased transcripts and increased peptide counts for genes in the core Rex regulon. We conclude that one mode of (per)chlorate and nitrate toxicity is as direct inhibitors of the central sulfate-reduction pathway. Our results demonstrate that (per)chlorate are more potent inhibitors than nitrate in both pure cultures and communities, implying that they represent an attractive alternative for controlling sulfidogenesis in industrial ecosystems. Of these, perchlorate offers better application logistics because of its inhibitory potency, solubility, relative chemical stability, low affinity for mineral cations and high mobility in environmental systems.
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Affiliation(s)
- Hans K Carlson
- Energy Biosciences Institute, UC Berkeley, Berkeley, CA, USA
| | - Jennifer V Kuehl
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Amrita B Hazra
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Nicholas B Justice
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Magdalena K Stoeva
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Andrew Sczesnak
- Department of Bioengineering, UC Berkeley, Berkeley, CA, USA
| | - Mark R Mullan
- Energy Biosciences Institute, UC Berkeley, Berkeley, CA, USA
| | - Anthony T Iavarone
- QB3/Chemistry Mass Spectrometry Facility, UC Berkeley, Berkeley, CA, USA
| | - Anna Engelbrektson
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Morgan N Price
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Adam M Deutschbauer
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Adam P Arkin
- 1] Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA [2] Department of Bioengineering, UC Berkeley, Berkeley, CA, USA
| | - John D Coates
- 1] Energy Biosciences Institute, UC Berkeley, Berkeley, CA, USA [2] Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
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Hartmann T, Leimkühler S. The oxygen-tolerant and NAD+-dependent formate dehydrogenase from Rhodobacter capsulatus is able to catalyze the reduction of CO2 to formate. FEBS J 2013; 280:6083-96. [PMID: 24034888 DOI: 10.1111/febs.12528] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/08/2013] [Accepted: 09/10/2013] [Indexed: 11/27/2022]
Abstract
The formate dehydrogenase from Rhodobacter capsulatus (RcFDH) is an oxygen-tolerant protein with an (αβγ)2 subunit composition that is localized in the cytoplasm. It belongs to the group of metal and NAD(+)-dependent FDHs with the coordination of a molybdenum cofactor, four [Fe4S4] clusters and one [Fe2S2] cluster associated with the α-subunit, one [Fe4S4] cluster and one FMN bound to the β-subunit, and one [Fe2S2] cluster bound to the γ-subunit. RcFDH was heterologously expressed in Escherichia coli and characterized. Cofactor analysis showed that the bis-molybdopterin guanine dinucleotide cofactor is bound to the FdsA subunit containing a cysteine ligand at the active site. A turnover rate of 2189 min(-1) with formate as substrate was determined. The back reaction for the reduction of CO2 was catalyzed with a k(cat) of 89 min(-1). The preference for formate oxidation shows an energy barrier for CO2 reduction of the enzyme. Furthermore, the FMN-containing and [Fe4S4]-containing β-subunit together with the [Fe2S2]-containing γ-subunit forms a diaphorase unit with activities for both NAD(+) reduction and NADH oxidation. In addition to the structural genes fdsG, fdsB, and fdsA, the fds operon in R. capsulatus contains the fdsC and fdsD genes. Expression studies showed that RcFDH is only active when both FdsC and FdsD are present. Both proteins are proposed to be involved in bis-molybdopterin guanine dinucleotide modification and insertion into RcFDH.
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Affiliation(s)
- Tobias Hartmann
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Germany
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Kozmin SG, Stepchenkova EI, Schaaper RM. TusA (YhhP) and IscS are required for molybdenum cofactor-dependent base-analog detoxification. Microbiologyopen 2013; 2:743-55. [PMID: 23894086 PMCID: PMC3831636 DOI: 10.1002/mbo3.108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 05/30/2013] [Accepted: 06/07/2013] [Indexed: 12/15/2022] Open
Abstract
Lack of molybdenum cofactor (Moco) in Escherichia coli leads to hypersensitivity to the mutagenic and toxic effects of N-hydroxylated base analogs, such as 6-N-hydroxylaminopurine (HAP). This phenotype is due to the loss of two Moco-dependent activities, YcbX and YiiM, that are capable of reducing HAP to adenine. Here, we describe two novel HAP-sensitive mutants containing a defect in iscS or tusA (yhhP) gene. IscS is a major L-cysteine desulfurase involved in iron-sulfur cluster synthesis, thiamine synthesis, and tRNA thiomodification. TusA is a small sulfur-carrier protein that interacts with IscS. We show that both IscS and TusA operate within the Moco-dependent pathway. Like other Moco-deficient strains, tusA and iscS mutants are HAP sensitive and resistant to chlorate under anaerobic conditions. The base-analog sensitivity of iscS or tusA strains could be suppressed by supplying exogenous L-cysteine or sulfide or by an increase in endogenous sulfur donors (cysB constitutive mutant). The data suggest that iscS and tusA mutants have a defect in the mobilization of sulfur required for active YcbX/YiiM proteins as well as nitrate reductase, presumably due to lack of functional Moco. Overall, our data imply a novel and indispensable role of the IscS/TusA complex in the activity of several molybdoenzymes.
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Affiliation(s)
- Stanislav G Kozmin
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, 27709
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Kozmin SG, Schaaper RM. Genetic characterization of moaB mutants of Escherichia coli. Res Microbiol 2013; 164:689-94. [PMID: 23680484 PMCID: PMC3743958 DOI: 10.1016/j.resmic.2013.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 05/02/2013] [Indexed: 11/26/2022]
Abstract
The moaABCDE operon of Escherichia coli encodes enzymes essential for the biosynthesis of the molybdenum cofactor (Moco). However, the role of the moaB gene within this operon has remained enigmatic. Here, we have investigated the effect of moaB defects on two phenotypes diagnostic for Moco-deficiency: chlorate-resistance and sensitivity to the base analog 6-N-hydroxylaminopurine (HAP). We found that transposon insertions in moaB caused partial Moco-deficiency associated with chlorate-resistance, but not for HAP-sensitivity. On the other hand, in-frame deletions of moaB, or moaB overexpression, had no effect on either phenotype. Our combined data are consistent with the lack of any role for MoaB in Moco biosynthesis in E. coli.
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Affiliation(s)
- Stanislav G. Kozmin
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Roel M. Schaaper
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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30
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Warelow TP, Oke M, Schoepp-Cothenet B, Dahl JU, Bruselat N, Sivalingam GN, Leimkühler S, Thalassinos K, Kappler U, Naismith JH, Santini JM. The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. PLoS One 2013; 8:e72535. [PMID: 24023621 PMCID: PMC3758308 DOI: 10.1371/journal.pone.0072535] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 07/10/2013] [Indexed: 11/18/2022] Open
Abstract
The arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxification, consists of a large α subunit (AioA) with bis-molybdopterin guanine dinucleotide at its active site and a 3Fe-4S cluster, and a small β subunit (AioB) which contains a Rieske 2Fe-2S cluster. The successful heterologous expression of the NT-26 Aio in Escherichia coli has resulted in the solution of its crystal structure. The NT-26 Aio, a heterotetramer, shares high overall similarity to the heterodimeric arsenite oxidase from A. faecalis but there are striking differences in the structure surrounding the Rieske 2Fe-2S cluster which we demonstrate explains the difference in the observed redox potentials (+225 mV vs. +130/160 mV, respectively). A combination of site-directed mutagenesis and electron paramagnetic resonance was used to explore the differences observed in the structure and redox properties of the Rieske cluster. In the NT-26 AioB the substitution of a serine (S126 in NT-26) for a threonine as in the A. faecalis AioB explains a -20 mV decrease in redox potential. The disulphide bridge in the A. faecalis AioB which is conserved in other betaproteobacterial AioB subunits and the Rieske subunit of the cytochrome bc 1 complex is absent in the NT-26 AioB subunit. The introduction of a disulphide bridge had no effect on Aio activity or protein stability but resulted in a decrease in the redox potential of the cluster. These results are in conflict with previous data on the betaproteobacterial AioB subunit and the Rieske of the bc 1 complex where removal of the disulphide bridge had no effect on the redox potential of the former but a decrease in cluster stability was observed in the latter.
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Affiliation(s)
- Thomas P. Warelow
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Muse Oke
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, United Kingdom
| | - Barbara Schoepp-Cothenet
- Laboratoire de Bioénergétique et Ingénierie des Protéines, BIP/CNRS, UMR7281, AMU, Marseille, France
| | - Jan U. Dahl
- Universität Potsdam, Institut für Biochemie and Biologie, Potsdam, Germany
| | - Nicole Bruselat
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Ganesh N. Sivalingam
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Silke Leimkühler
- Universität Potsdam, Institut für Biochemie and Biologie, Potsdam, Germany
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Ulrike Kappler
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - James H. Naismith
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, United Kingdom
| | - Joanne M. Santini
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
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31
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Ringel P, Krausze J, van den Heuvel J, Curth U, Pierik AJ, Herzog S, Mendel RR, Kruse T. Biochemical characterization of molybdenum cofactor-free nitrate reductase from Neurospora crassa. J Biol Chem 2013; 288:14657-14671. [PMID: 23539622 DOI: 10.1074/jbc.m113.457960] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nitrate reductase (NR) is a complex molybdenum cofactor (Moco)-dependent homodimeric metalloenzyme that is vitally important for autotrophic organism as it catalyzes the first and rate-limiting step of nitrate assimilation. Beside Moco, eukaryotic NR also binds FAD and heme as additional redox active cofactors, and these are involved in electron transfer from NAD(P)H to the enzyme molybdenum center where reduction of nitrate to nitrite takes place. We report the first biochemical characterization of a Moco-free eukaryotic NR from the fungus Neurospora crassa, documenting that Moco is necessary and sufficient to induce dimer formation. The molybdenum center of NR reconstituted in vitro from apo-NR and Moco showed an EPR spectrum identical to holo-NR. Analysis of mutants unable to bind heme or FAD revealed that insertion of Moco into NR occurs independent from the insertion of any other NR redox cofactor. Furthermore, we showed that at least in vitro the active site formation of NR is an autonomous process.
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Affiliation(s)
- Phillip Ringel
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Joern Krausze
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Joop van den Heuvel
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Ute Curth
- Institute for Biophysical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Antonio J Pierik
- Core Facility for Protein Spectroscopy, Institute of Cytobiology and Cytopathology, Phillips University, 35032 Marburg, Germany
| | - Stephanie Herzog
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Ralf R Mendel
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany.
| | - Tobias Kruse
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
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32
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Lee J, Cho MH, Lee J. Characterization of an oxygen-dependent inducible promoter system, the nar promoter, and Escherichia coli with an inactivated nar operon. Biotechnol Bioeng 2012; 52:572-8. [PMID: 18629930 DOI: 10.1002/(sici)1097-0290(19961205)52:5<572::aid-bit4>3.0.co;2-g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The nar promoter of Escherichia coli, which is maximally induced under anaerobic conditions in the presence of nitrate, was characterized to see whether the nar promoter cloned onto pBR322 can be used as an inducible promoter. To increase the expression level, the nar promoter was expressed in E. coli where active nitrate reductase cannot be expressed from the nar operon on the chromosome. A plasmid with the lacZ gene expressing beta-galactosidase instead of the structural genes of the nar operon was used to simplify an assay of induction of the nar promoter. The following effects were investigated to find optimal conditions: methods of inducing the nar promoter, optimal nitrate and molybdate concentrations maximally inducing the nar promoter, the amount of expressed beta-galactosidase, and induction ratio (specific beta-galactosidase activity after maximal induction/specific beta-galactosidase activity before induction). The following results were obtained from the experiments: induction of the nar promoter was optimal when E. coli was grown in the presence of 1% nitrate at the beginning of culture; expression of beta-galactosidase was not affected by molybdate; the induction ratio was maximal, approximately 300, when the overnight culture was grown in the flask for 2.5 h (OD(600) is congruent to 1.3) before being transferred to the fermentor; the amount of beta-galactosidase per cell and per medium volume was maximal when E. coli was grown under aerobic conditions to OD(600) = 1.7; then the nar promoter was induced under microaerobic conditions made by lowering dissolved oxygen level (DO) to 1-2%. After approximately 6 h of induction, OD(600) became 3.2 and specific beta-galactosidase activity became 36,000 Miller units, equivalent to 35% of total cellular proteins, which was confirmed from sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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Affiliation(s)
- J Lee
- Department of Chemical Engineering, School of Engineering, Yeungnam University, Kyungbuk, Korea
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33
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Oxidative stress modulates the nitric oxide defense promoted by Escherichia coli flavorubredoxin. J Bacteriol 2012; 194:3611-7. [PMID: 22563051 DOI: 10.1128/jb.00140-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mammalian cells of innate immunity respond to pathogen invasion by activating proteins that generate a burst of oxidative and nitrosative stress. Pathogens defend themselves from the toxic compounds by triggering a variety of detoxifying enzymes. Escherichia coli flavorubredoxin is a nitric oxide reductase that is expressed under nitrosative stress conditions. We report that in contrast to nitrosative stress alone, exposure to both nitrosative and oxidative stresses abolishes the expression of flavorubredoxin. Electron paramagnetic resonance (EPR) experiments showed that under these conditions, the iron center of the flavorubredoxin transcription activator NorR loses the ability to bind nitric oxide. Accordingly, triggering of the NorR ATPase activity, a requisite for flavorubredoxin activation, was impaired by treatment of the protein with the double stress. Studies of macrophages revealed that the contribution of flavorubredoxin to the survival of E. coli depends on the stage of macrophage infection and that the lack of protection observed at the early phase is related to inhibition of NorR activity by the oxidative burst. We propose that the time-dependent activation of flavorubredoxin contributes to the adaptation of E. coli to the different fluxes of hydrogen peroxide and nitric oxide to which the bacterium is subjected during the course of macrophage infection.
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34
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Vine CE, Purewal SK, Cole JA. NsrR-dependent method for detecting nitric oxide accumulation in the Escherichia coli cytoplasm and enzymes involved in NO production. FEMS Microbiol Lett 2011; 325:108-14. [DOI: 10.1111/j.1574-6968.2011.02385.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 07/29/2011] [Accepted: 08/09/2011] [Indexed: 11/30/2022] Open
Affiliation(s)
- Claire E. Vine
- School of Biosciences; University of Birmingham; Birmingham; UK
| | | | - Jeffrey A. Cole
- School of Biosciences; University of Birmingham; Birmingham; UK
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35
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Leimkühler S, Wuebbens MM, Rajagopalan K. The History of the Discovery of the Molybdenum Cofactor and Novel Aspects of its Biosynthesis in Bacteria. Coord Chem Rev 2011; 255:1129-1144. [PMID: 21528011 PMCID: PMC3081585 DOI: 10.1016/j.ccr.2010.12.003] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Biosynthesis of the molybdenum cofactor in bacteria is described with a detailed analysis of each individual reaction leading to the formation of stable intermediates during the synthesis of molybdopterin from GTP. As a starting point, the discovery of molybdopterin and the elucidation of its structure through the study of stable degradation products are described. Subsequent to molybdopterin synthesis, the molybdenum atom is added to the molybdopterin dithiolene group to form the molybdenum cofactor. This cofactor is either inserted directly into specific molybdoenzymes or is further modified by the addition of nucleotides to the molybdopterin phosphate group or the replacement of ligands at the molybdenum center.
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Affiliation(s)
- Silke Leimkühler
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, 14476 Potsdam, Germany
| | - Margot M. Wuebbens
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - K.V. Rajagopalan
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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36
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Abstract
The ability of enteric bacteria to protect themselves against reactive nitrogen species generated by their own metabolism, or as part of the innate immune response, is critical to their survival. One important defence mechanism is their ability to reduce NO (nitric oxide) to harmless products. The highest rates of NO reduction by Escherichia coli K-12 were detected after anaerobic growth in the presence of nitrate. Four proteins have been implicated as catalysts of NO reduction: the cytoplasmic sirohaem-containing nitrite reductase, NirB; the periplasmic cytochrome c nitrite reductase, NrfA; the flavorubredoxin NorV and its associated oxidoreductase, NorW; and the flavohaemoglobin, Hmp. Single mutants defective in any one of these proteins and even the mutant defective in all four proteins reduced NO at the same rate as the parent. Clearly, therefore, there are mechanisms of NO reduction by enteric bacteria that remain to be characterized. Far from being minor pathways, the currently unknown pathways are adequate to sustain almost optimal rates of NO reduction, and hence potentially provide significant protection against nitrosative stress.
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37
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Kim NJ, Choi JH, Kim YC, Lee J, Lee SY, Chang HN, Lee PC. Development of anaerobically inducible nar promoter expression vectors for the expression of recombinant proteins in Escherichia coli. J Biotechnol 2011; 151:102-7. [DOI: 10.1016/j.jbiotec.2010.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 10/24/2010] [Accepted: 11/15/2010] [Indexed: 11/15/2022]
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38
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Wahl B, Reichmann D, Niks D, Krompholz N, Havemeyer A, Clement B, Messerschmidt T, Rothkegel M, Biester H, Hille R, Mendel RR, Bittner F. Biochemical and spectroscopic characterization of the human mitochondrial amidoxime reducing components hmARC-1 and hmARC-2 suggests the existence of a new molybdenum enzyme family in eukaryotes. J Biol Chem 2010; 285:37847-59. [PMID: 20861021 PMCID: PMC2988388 DOI: 10.1074/jbc.m110.169532] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 09/17/2010] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial amidoxime reducing component mARC is a newly discovered molybdenum enzyme that is presumed to form the catalytical part of a three-component enzyme system, consisting of mARC, heme/cytochrome b(5), and NADH/FAD-dependent cytochrome b(5) reductase. mARC proteins share a significant degree of homology to the molybdenum cofactor-binding domain of eukaryotic molybdenum cofactor sulfurase proteins, the latter catalyzing the post-translational activation of aldehyde oxidase and xanthine oxidoreductase. The human genome harbors two mARC genes, referred to as hmARC-1/MOSC-1 and hmARC-2/MOSC-2, which are organized in a tandem arrangement on chromosome 1. Recombinant expression of hmARC-1 and hmARC-2 proteins in Escherichia coli reveals that both proteins are monomeric in their active forms, which is in contrast to all other eukaryotic molybdenum enzymes that act as homo- or heterodimers. Both hmARC-1 and hmARC-2 catalyze the N-reduction of a variety of N-hydroxylated substrates such as N-hydroxy-cytosine, albeit with different specificities. Reconstitution of active molybdenum cofactor onto recombinant hmARC-1 and hmARC-2 proteins in the absence of sulfur indicates that mARC proteins do not belong to the xanthine oxidase family of molybdenum enzymes. Moreover, they also appear to be different from the sulfite oxidase family, because no cysteine residue could be identified as a putative ligand of the molybdenum atom. This suggests that the hmARC proteins and sulfurase represent members of a new family of molybdenum enzymes.
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Affiliation(s)
- Bettina Wahl
- From the Department of Plant Biology, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Debora Reichmann
- From the Department of Plant Biology, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Dimitri Niks
- the Department of Biochemistry, University of California, Riverside, California 92521
| | - Nina Krompholz
- the Pharmaceutical Institute, Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-Universität Kiel, 24118 Kiel, Germany, and
| | - Antje Havemeyer
- the Pharmaceutical Institute, Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-Universität Kiel, 24118 Kiel, Germany, and
| | - Bernd Clement
- the Pharmaceutical Institute, Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-Universität Kiel, 24118 Kiel, Germany, and
| | | | | | - Harald Biester
- Environmental Geology, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Russ Hille
- the Department of Biochemistry, University of California, Riverside, California 92521
| | - Ralf R. Mendel
- From the Department of Plant Biology, Technische Universität Braunschweig, 38023 Braunschweig, Germany
| | - Florian Bittner
- From the Department of Plant Biology, Technische Universität Braunschweig, 38023 Braunschweig, Germany
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Ogino K, Ramsden SL, Keib N, Schwarz G, Harvey RJ, Hirata H. Duplicated gephyrin genes showing distinct tissue distribution and alternative splicing patterns mediate molybdenum cofactor biosynthesis, glycine receptor clustering, and escape behavior in zebrafish. J Biol Chem 2010; 286:806-17. [PMID: 20843816 DOI: 10.1074/jbc.m110.125500] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gephyrin mediates the postsynaptic clustering of glycine receptors (GlyRs) and GABA(A) receptors at inhibitory synapses and molybdenum-dependent enzyme (molybdoenzyme) activity in non-neuronal tissues. Gephyrin knock-out mice show a phenotype resembling both defective glycinergic transmission and molybdenum cofactor (Moco) deficiency and die within 1 day of birth due to starvation and dyspnea resulting from deficits in motor and respiratory networks, respectively. To address whether gephyrin function is conserved among vertebrates and whether gephyrin deficiency affects molybdoenzyme activity and motor development, we cloned and characterized zebrafish gephyrin genes. We report here that zebrafish have two gephyrin genes, gphna and gphnb. The former is expressed in all tissues and has both C3 and C4 cassette exons, and the latter is expressed predominantly in the brain and spinal cord and harbors only C4 cassette exons. We confirmed that all of the gphna and gphnb splicing isoforms have Moco synthetic activity. Antisense morpholino knockdown of either gphna or gphnb alone did not disturb synaptic clusters of GlyRs in the spinal cord and did not affect touch-evoked escape behaviors. However, on knockdown of both gphna and gphnb, embryos showed impairments in GlyR clustering in the spinal cord and, as a consequence, demonstrated touch-evoked startle response behavior by contracting antagonistic muscles simultaneously, instead of displaying early coiling and late swimming behaviors, which are executed by side-to-side muscle contractions. These data indicate that duplicated gephyrin genes mediate Moco biosynthesis and control postsynaptic clustering of GlyRs, thereby mediating key escape behaviors in zebrafish.
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Affiliation(s)
- Kazutoyo Ogino
- Center for Frontier Research, National Institute of Genetics, 1111 Yata, Mishima 411-8540, Japan
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40
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Kruse T, Gehl C, Geisler M, Lehrke M, Ringel P, Hallier S, Hänsch R, Mendel RR. Identification and biochemical characterization of molybdenum cofactor-binding proteins from Arabidopsis thaliana. J Biol Chem 2009; 285:6623-35. [PMID: 20040598 DOI: 10.1074/jbc.m109.060640] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor (Moco) forms part of the catalytic center in all eukaryotic molybdenum enzymes and is synthesized in a highly conserved pathway. Among eukaryotes, very little is known about the processes taking place subsequent to Moco biosynthesis, i.e. Moco transfer, allocation, and insertion into molybdenum enzymes. In the model plant Arabidopsis thaliana, we identified a novel protein family consisting of nine members that after recombinant expression are able to bind Moco with K(D) values in the low micromolar range and are therefore named Moco-binding proteins (MoBP). For two of the nine proteins atomic structures are available in the Protein Data Bank. Surprisingly, both crystal structures lack electron density for the C terminus, which may indicate a high flexibility of this part of the protein. C-terminal truncated MoBPs showed significantly decreased Moco binding stoichiometries. Experiments where the MoBP C termini were exchanged among MoBPs converted a weak Moco-binding MoBP into a strong binding MoBP, thus indicating that the MoBP C terminus, which is encoded by a separate exon, is involved in Moco binding. MoBPs were able to enhance Moco transfer to apo-nitrate reductase in the Moco-free Neurospora crassa mutant nit-1. Furthermore, we show that the MoBPs are localized in the cytosol and undergo protein-protein contact with both the Moco donor protein Cnx1 and the Moco acceptor protein nitrate reductase under in vivo conditions, thus indicating for the MoBPs a function in Arabidopsis cellular Moco distribution.
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Affiliation(s)
- Tobias Kruse
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
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41
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Production of 3-nitrosoindole derivatives by Escherichia coli during anaerobic growth. J Bacteriol 2009; 191:5369-76. [PMID: 19561128 DOI: 10.1128/jb.00586-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When Escherichia coli K-12 is grown anaerobically in medium containing tryptophan and sodium nitrate, it produces red compounds. The reaction requires functional genes for trytophanase (tnaA), a tryptophan permease (tnaB), and a nitrate reductase (narG), as well as a natural drop in the pH of the culture. Mass spectrometry revealed that the purified chromophores had mass/charge ratios that closely match those for indole red, indoxyl red, and an indole trimer. These compounds are known products of chemical reactions between indole and nitrous acid. They are derived from an initial reaction of 3-nitrosoindole with indole. Apparently, nitrite that is produced from the metabolic reduction of nitrate is converted in the acid medium to nitrous acid, which leads to the nitrosation of the indole that is generated by tryptophanase. An nfi (endonuclease V) mutant and a recA mutant were selectively killed during the period of chromophore production, and a uvrA strain displayed reduced growth. These effects depended on the addition of nitrate to the medium and on tryptophanase activity in the cells. Unexpectedly, the killing of a tnaA(+) nfi mutant was not accompanied by marked increases in mutation frequencies for several traits tested. The vulnerability of three DNA repair mutants indicates that a nitrosoindole or a derivative of a nitrosoindole produces lethal DNA damage.
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Malone A, Chung YK, Yousef A. Proposed mechanism of inactivatingEscherichia coliO157:H7 by ultra-high pressure in combination withtert-butylhydroquinone. J Appl Microbiol 2008; 105:2046-57. [DOI: 10.1111/j.1365-2672.2008.03973.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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43
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Neumann M, Leimkühler S. Heavy metal ions inhibit molybdoenzyme activity by binding to the dithiolene moiety of molybdopterin in Escherichia coli. FEBS J 2008; 275:5678-89. [DOI: 10.1111/j.1742-4658.2008.06694.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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44
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Kozmin SG, Leroy P, Pavlov YI, Schaaper RM. YcbX and yiiM, two novel determinants for resistance of Escherichia coli to N-hydroxylated base analogues. Mol Microbiol 2008; 68:51-65. [PMID: 18312271 PMCID: PMC2740630 DOI: 10.1111/j.1365-2958.2008.06128.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
We have shown previously that lack of molybdenum cofactor (MoCo) in Escherichia coli leads to hypersensitivity to the mutagenic and toxic effects of N-hydroxylated base analogues, such as 6-N-hydroxylaminopurine (HAP). However, the nature of the MoCo-dependent mechanism is unknown, as inactivation of all known and putative E. coli molybdoenzymes does not produce any sensitivity. Presently, we report on the isolation and characterization of two novel HAP-hypersensitive mutants carrying defects in the ycbX or yiiM open reading frames. Genetic analysis suggests that the two genes operate within the MoCo-dependent pathway. In the absence of the ycbX- and yiiM-dependent pathways, biotin sulfoxide reductase plays also a role in the detoxification pathway. YcbX and YiiM are hypothetical members of the MOSC protein superfamily, which contain the C-terminal domain (MOSC) of the eukaryotic MoCo sulphurases. However, deletion of ycbX or yiiM did not affect the activity of human xanthine dehydrogenase expressed in E. coli, suggesting that the role of YcbX and YiiM proteins is not related to MoCo sulphuration. Instead, YcbX and YiiM may represent novel MoCo-dependent enzymatic activities. We also demonstrate that the MoCo/YcbX/YiiM-dependent detoxification of HAP proceeds by reduction to adenine.
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Affiliation(s)
- Stanislav G Kozmin
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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45
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Wollers S, Heidenreich T, Zarepour M, Zachmann D, Kraft C, Zhao Y, Mendel RR, Bittner F. Binding of Sulfurated Molybdenum Cofactor to the C-terminal Domain of ABA3 from Arabidopsis thaliana Provides Insight into the Mechanism of Molybdenum Cofactor Sulfuration. J Biol Chem 2008; 283:9642-50. [DOI: 10.1074/jbc.m708549200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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46
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Bröcker MJ, Virus S, Ganskow S, Heathcote P, Heinz DW, Schubert WD, Jahn D, Moser J. ATP-driven reduction by dark-operative protochlorophyllide oxidoreductase from Chlorobium tepidum mechanistically resembles nitrogenase catalysis. J Biol Chem 2008; 283:10559-67. [PMID: 18252716 DOI: 10.1074/jbc.m708010200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During chlorophyll and bacteriochlorophyll biosynthesis in gymnosperms, algae, and photosynthetic bacteria, dark-operative protochlorophyllide oxidoreductase (DPOR) reduces ring D of aromatic protochlorophyllide stereospecifically to produce chlorophyllide. We describe the heterologous overproduction of DPOR subunits BchN, BchB, and BchL from Chlorobium tepidum in Escherichia coli allowing their purification to apparent homogeneity. The catalytic activity was found to be 3.15 nmol min(-1) mg(-1) with K(m) values of 6.1 microm for protochlorophyllide, 13.5 microm for ATP, and 52.7 microm for the reductant dithionite. To identify residues important in DPOR function, 21 enzyme variants were generated by site-directed mutagenesis and investigated for their metal content, spectroscopic features, and catalytic activity. Two cysteine residues (Cys(97) and Cys(131)) of homodimeric BchL(2) are found to coordinate an intersubunit [4Fe-4S] cluster, essential for low potential electron transfer to (BchNB)(2) as part of the reduction of the protochlorophyllide substrate. Similarly, Lys(10) and Leu(126) are crucial to ATP-driven electron transfer from BchL(2). The activation energy of DPOR electron transfer is 22.2 kJ mol(-1) indicating a requirement for 4 ATP per catalytic cycle. At the amino acid level, BchL is 33% identical to the nitrogenase subunit NifH allowing a first tentative structural model to be proposed. In (BchNB)(2), we find that four cysteine residues, three from BchN (Cys(21), Cys(46), and Cys(103)) and one from BchB (Cys(94)), coordinate a second inter-subunit [4Fe-4S] cluster required for catalysis. No evidence for any type of molybdenum-containing cofactor was found, indicating that the DPOR subunit BchN clearly differs from the homologous nitrogenase subunit NifD. Based on the available data we propose an enzymatic mechanism of DPOR.
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Affiliation(s)
- Markus J Bröcker
- Institute of Microbiology, Technical University Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany
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Jones SA, Chowdhury FZ, Fabich AJ, Anderson A, Schreiner DM, House AL, Autieri SM, Leatham MP, Lins JJ, Jorgensen M, Cohen PS, Conway T. Respiration of Escherichia coli in the mouse intestine. Infect Immun 2007; 75:4891-9. [PMID: 17698572 PMCID: PMC2044527 DOI: 10.1128/iai.00484-07] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 06/01/2007] [Accepted: 07/30/2007] [Indexed: 12/24/2022] Open
Abstract
Mammals are aerobes that harbor an intestinal ecosystem dominated by large numbers of anaerobic microorganisms. However, the role of oxygen in the intestinal ecosystem is largely unexplored. We used systematic mutational analysis to determine the role of respiratory metabolism in the streptomycin-treated mouse model of intestinal colonization. Here we provide evidence that aerobic respiration is required for commensal and pathogenic Escherichia coli to colonize mice. Our results showed that mutants lacking ATP synthase, which is required for all respiratory energy-conserving metabolism, were eliminated by competition with respiratory-competent wild-type strains. Mutants lacking the high-affinity cytochrome bd oxidase, which is used when oxygen tensions are low, also failed to colonize. However, the low-affinity cytochrome bo(3) oxidase, which is used when oxygen tension is high, was found not to be necessary for colonization. Mutants lacking either nitrate reductase or fumarate reductase also had major colonization defects. The results showed that the entire E. coli population was dependent on both microaerobic and anaerobic respiration, consistent with the hypothesis that the E. coli niche is alternately microaerobic and anaerobic, rather than static. The results indicate that success of the facultative anaerobes in the intestine depends on their respiratory flexibility. Despite competition for relatively scarce carbon sources, the energy efficiency provided by respiration may contribute to the widespread distribution (i.e., success) of E. coli strains as commensal inhabitants of the mammalian intestine.
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Affiliation(s)
- Shari A Jones
- Advanced Center for Genome Technology, University of Oklahoma, Norman, Oklahoma 73019, USA
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48
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Filenko N, Spiro S, Browning DF, Squire D, Overton TW, Cole J, Constantinidou C. The NsrR regulon of Escherichia coli K-12 includes genes encoding the hybrid cluster protein and the periplasmic, respiratory nitrite reductase. J Bacteriol 2007; 189:4410-7. [PMID: 17449618 PMCID: PMC1913375 DOI: 10.1128/jb.00080-07] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 04/10/2007] [Indexed: 11/20/2022] Open
Abstract
Successful pathogens must be able to protect themselves against reactive nitrogen species generated either as part of host defense mechanisms or as products of their own metabolism. The regulatory protein NsrR (a member of the Rrf2 family of transcription factors) plays key roles in this stress response. Microarray analysis revealed that NsrR represses nine operons encoding 20 genes in Escherichia coli MG1655, including the hmpA, ytfE, and ygbA genes that were previously shown to be regulated by NsrR. Novel NsrR targets revealed by this study include hcp-hcr (which were predicted in a recent bioinformatic study to be NsrR regulated) and the well-studied nrfA promoter that directs the expression of the periplasmic respiratory nitrite reductase. Conversely, transcription from the ydbC promoter is strongly activated by NsrR. Regulation of the nrf operon by NsrR is consistent with the ability of the periplasmic nitrite reductase to reduce nitric oxide and hence protect against reactive nitrogen species. Gel retardation assays were used to show that both FNR and NarL bind to the hcp promoter. The expression of hcp and the contiguous gene hcr is not induced by hydroxylamine. As hmpA and ytfE encode a nitric oxide reductase and a mechanism to repair iron-sulfur centers damaged by nitric oxide, the demonstration that hcp-hcr, hmpA, and ytfE are the three transcripts most tightly regulated by NsrR highlights the possibility that the hybrid cluster protein, HCP, might also be part of a defense mechanism against reactive nitrogen stress.
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Affiliation(s)
- Nina Filenko
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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49
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Llamas A, Tejada-Jimenez M, González-Ballester D, Higuera JJ, Schwarz G, Galván A, Fernández E. Chlamydomonas reinhardtii CNX1E reconstitutes molybdenum cofactor biosynthesis in Escherichia coli mutants. EUKARYOTIC CELL 2007; 6:1063-7. [PMID: 17416894 PMCID: PMC1951514 DOI: 10.1128/ec.00072-07] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have isolated and characterized the Chlamydomonas reinhardtii genes for molybdenum cofactor biosynthesis, namely, CNX1G and CNX1E, and expressed them and their chimeric fusions in Chlamydomonas and Escherichia coli. In all cases, the wild-type phenotype was restored in individual mutants as well as in a CNX1G CNX1E double mutant. Therefore, CrCNX1E is the first eukaryotic protein able to complement an E. coli moeA mutant.
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Affiliation(s)
- Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 14071 Córdoba, Spain
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50
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Nichols JD, Xiang S, Schindelin H, Rajagopalan KV. Mutational analysis of Escherichia coli MoeA: two functional activities map to the active site cleft. Biochemistry 2007; 46:78-86. [PMID: 17198377 PMCID: PMC1868504 DOI: 10.1021/bi061551q] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molybdenum cofactor is ubiquitous in nature, and the pathway for Moco biosynthesis is conserved in all three domains of life. Recent work has helped to illuminate one of the most enigmatic steps in Moco biosynthesis, ligation of metal to molybdopterin (the organic component of the cofactor) to form the active cofactor. In Escherichia coli, the MoeA protein mediates ligation of Mo to molybdopterin while the MogA protein enhances this process in an ATP-dependent manner. The X-ray crystal structures for both proteins have been previously described as well as two essential MogA residues, Asp49 and Asp82. Here we describe a detailed mutational analysis of the MoeA protein. Variants of conserved residues at the putative active site of MoeA were analyzed for a loss of function in two different, previously described assays, one employing moeA- crude extracts and the other utilizing a defined system. Oddly, no correlation was observed between the activity in the two assays. In fact, our results showed a general trend toward an inverse relationship between the activity in each assay. Moco binding studies indicated a strong correlation between a variant's ability to bind Moco and its activity in the purified component assay. Crystal structures of the functionally characterized MoeA variants revealed no major structural changes, indicating that the functional differences observed are not due to disruption of the protein structure. On the basis of these results, two different functional areas were assigned to regions at or near the MoeA active site cleft.
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Affiliation(s)
- Jason D Nichols
- Department of Biochemistry, Duke University Medical Center Durham, NC 27710, USA
| | - Song Xiang
- Department of Biochemistry and Center for Structural Biology, State University of New York at Stony Brook, Stony Brook, NY 11794-5115, USA
| | - Hermann Schindelin
- Department of Biochemistry and Center for Structural Biology, State University of New York at Stony Brook, Stony Brook, NY 11794-5115, USA
- Rudolf Virchow Centre for Experimental Biomedicine and Institute of Structural Biology, University of Würzburg, Versbacher Str. 9, 97078 Würzburg, Germany
| | - K. V. Rajagopalan
- Department of Biochemistry, Duke University Medical Center Durham, NC 27710, USA
- * To whom correspondence should be addressed, Phone: (919) 681-8845, Fax: (919) 684-8919,
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