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Adamus JP, Ruszczyńska A, Wyczałkowska-Tomasik A. Molybdenum's Role as an Essential Element in Enzymes Catabolizing Redox Reactions: A Review. Biomolecules 2024; 14:869. [PMID: 39062583 PMCID: PMC11275037 DOI: 10.3390/biom14070869] [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: 06/04/2024] [Revised: 07/05/2024] [Accepted: 07/16/2024] [Indexed: 07/28/2024] Open
Abstract
Molybdenum (Mo) is an essential element for human life, acting as a cofactor in various enzymes crucial for metabolic homeostasis. This review provides a comprehensive insight into the latest advances in research on molybdenum-containing enzymes and their clinical significance. One of these enzymes is xanthine oxidase (XO), which plays a pivotal role in purine catabolism, generating reactive oxygen species (ROS) capable of inducing oxidative stress and subsequent organ dysfunction. Elevated XO activity is associated with liver pathologies such as non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC). Aldehyde oxidases (AOs) are also molybdenum-containing enzymes that, similar to XO, participate in drug metabolism, with notable roles in the oxidation of various substrates. However, beneath its apparent efficacy, AOs' inhibition may impact drug effectiveness and contribute to liver damage induced by hepatotoxins. Another notable molybdenum-enzyme is sulfite oxidase (SOX), which catalyzes the conversion of sulfite to sulfate, crucial for the degradation of sulfur-containing amino acids. Recent research highlights SOX's potential as a diagnostic marker for HCC, offering promising sensitivity and specificity in distinguishing cancerous lesions. The newest member of molybdenum-containing enzymes is mitochondrial amidoxime-reducing component (mARC), involved in drug metabolism and detoxification reactions. Emerging evidence suggests its involvement in liver pathologies such as HCC and NAFLD, indicating its potential as a therapeutic target. Overall, understanding the roles of molybdenum-containing enzymes in human physiology and disease pathology is essential for advancing diagnostic and therapeutic strategies for various health conditions, particularly those related to liver dysfunction. Further research into the molecular mechanisms underlying these enzymes' functions could lead to novel treatments and improved patient outcomes.
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Affiliation(s)
- Jakub Piotr Adamus
- Faculty of Medicine, Medical University of Warsaw, 02-091 Warsaw, Poland
| | - Anna Ruszczyńska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, 02-089 Warsaw, Poland
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Struwe MA, Scheidig AJ, Clement B. The mitochondrial amidoxime reducing component-from prodrug-activation mechanism to drug-metabolizing enzyme and onward to drug target. J Biol Chem 2023; 299:105306. [PMID: 37778733 PMCID: PMC10637980 DOI: 10.1016/j.jbc.2023.105306] [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: 06/19/2023] [Revised: 09/17/2023] [Accepted: 09/24/2023] [Indexed: 10/03/2023] Open
Abstract
The mitochondrial amidoxime-reducing component (mARC) is one of five known molybdenum enzymes in eukaryotes. mARC belongs to the MOSC domain superfamily, a large group of so far poorly studied molybdoenzymes. mARC was initially discovered as the enzyme activating N-hydroxylated prodrugs of basic amidines but has since been shown to also reduce a variety of other N-oxygenated compounds, for example, toxic nucleobase analogs. Under certain circumstances, mARC might also be involved in reductive nitric oxide synthesis through reduction of nitrite. Recently, mARC enzymes have received a lot of attention due to their apparent involvement in lipid metabolism and, in particular, because many genome-wide association studies have shown a common variant of human mARC1 to have a protective effect against liver disease. The mechanism linking mARC enzymes with lipid metabolism remains unknown. Here, we give a comprehensive overview of what is currently known about mARC enzymes, their substrates, structure, and apparent involvement in human disease.
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Affiliation(s)
- Michel A Struwe
- Zoologisches Institut - Strukturbiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany; Pharmazeutisches Institut, Christian-Albrechts-Universität Kiel, Kiel, Germany.
| | - Axel J Scheidig
- Zoologisches Institut - Strukturbiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | - Bernd Clement
- Pharmazeutisches Institut, Christian-Albrechts-Universität Kiel, Kiel, Germany
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3
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Clement B, Struwe MA. The History of mARC. Molecules 2023; 28:4713. [PMID: 37375270 DOI: 10.3390/molecules28124713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/08/2023] [Accepted: 06/10/2023] [Indexed: 06/29/2023] Open
Abstract
The mitochondrial amidoxime-reducing component (mARC) is the most recently discovered molybdoenzyme in humans after sulfite oxidase, xanthine oxidase and aldehyde oxidase. Here, the timeline of mARC's discovery is briefly described. The story begins with investigations into N-oxidation of pharmaceutical drugs and model compounds. Many compounds are N-oxidized extensively in vitro, but it turned out that a previously unknown enzyme catalyzes the retroreduction of the N-oxygenated products in vivo. After many years, the molybdoenzyme mARC could finally be isolated and identified in 2006. mARC is an important drug-metabolizing enzyme and N-reduction by mARC has been exploited very successfully for prodrug strategies, that allow oral administration of otherwise poorly bioavailable therapeutic drugs. Recently, it was demonstrated that mARC is a key factor in lipid metabolism and likely involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). The exact link between mARC and lipid metabolism is not yet fully understood. Regardless, many now consider mARC a potential drug target for the prevention or treatment of liver diseases. This article focusses on discoveries related to mammalian mARC enzymes. mARC homologues have been studied in algae, plants and bacteria. These will not be discussed extensively here.
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Affiliation(s)
- Bernd Clement
- Pharmazeutisches Institut, Christian-Albrechts-Universität zu Kiel, Gutenbergstraße 76, 24118 Kiel, Germany
| | - Michel A Struwe
- Pharmazeutisches Institut, Christian-Albrechts-Universität zu Kiel, Gutenbergstraße 76, 24118 Kiel, Germany
- Zoologisches Institut-Strukturbiologie, Zentrum für Biochemie und Molekularbiologie, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
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Yang J, Struwe M, Scheidig A, Mengell J, Clement B, Kirk ML. Active Site Structures of the Escherichia coli N-Hydroxylaminopurine Resistance Molybdoenzyme YcbX. Inorg Chem 2023; 62:5315-5319. [PMID: 36971376 PMCID: PMC10544827 DOI: 10.1021/acs.inorgchem.3c00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data have been used to characterize the coordination environment for the catalytic Mo site of Escherichia coli YcbX in two different oxidation states. In the oxidized state, the Mo(VI) ion is coordinated by two terminal oxo ligands, a thiolate S atom from cysteine, and two S donors from the bidentate pyranopterin ene-1,2-dithiolate (pyranopterin dithiolene). Upon reduction, it is the more basic equatorial oxo ligand that is protonated, with a Mo-Oeq bond distance that is best described as either a short Mo4+-OH2 bond or a long Mo4+-OH bond. Mechanistic implications for substrate reduction are discussed in light of these structural details.
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Affiliation(s)
- Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001
| | - Michel Struwe
- Zoologisches Institut – Strukturbiologie, Zentrum für Biochemie und Molekularbiologie Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
- Pharmazeutisches Institut, Christian-Albrechts-Universität zu Kiel, Gutenbergstraße 76, 24118 Kiel, Germany
| | - Axel Scheidig
- Zoologisches Institut – Strukturbiologie, Zentrum für Biochemie und Molekularbiologie Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Joshua Mengell
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001
| | - Bernd Clement
- Pharmazeutisches Institut, Christian-Albrechts-Universität zu Kiel, Gutenbergstraße 76, 24118 Kiel, Germany
| | - 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
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MoaE Is Involved in Response to Oxidative Stress in Deinococcus radiodurans. Int J Mol Sci 2023; 24:ijms24032441. [PMID: 36768763 PMCID: PMC9916421 DOI: 10.3390/ijms24032441] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/19/2023] [Accepted: 01/22/2023] [Indexed: 01/28/2023] Open
Abstract
Molybdenum ions are covalently bound to molybdenum pterin (MPT) to produce molybdenum cofactor (Moco), a compound essential for the catalytic activity of molybdenum enzymes, which is involved in a variety of biological functions. MoaE is the large subunit of MPT synthase and plays a key role in Moco synthesis. Here, we investigated the function of MoaE in Deinococcus radiodurans (DrMoaE) in vitro and in vivo, demonstrating that the protein contributed to the extreme resistance of D. radiodurans. The crystal structure of DrMoaE was determined by 1.9 Å resolution. DrMoaE was shown to be a dimer and the dimerization disappeared after Arg110 had been mutated. The deletion of drmoaE resulted in sensitivity to DNA damage stress and a slower growth rate in D. radiodurans. The increase in drmoaE transcript levels the and accumulation of intracellular reactive oxygen species levels under oxidative stress suggested that it was involved in the antioxidant process in D. radiodurans. In addition, treatment with the base analog 6-hydroxyaminopurine decreased survival and increased intracellular mutation rates in drmoaE deletion mutant strains. Our results reveal that MoaE plays a role in response to external stress mainly through oxidative stress resistance mechanisms in D. radiodurans.
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Kalimuthu P, Harmer JR, Baldauf M, Hassan AH, Kruse T, Bernhardt PV. Catalytic electrochemistry of the bacterial Molybdoenzyme YcbX. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148579. [PMID: 35640667 DOI: 10.1016/j.bbabio.2022.148579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/02/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Molybdenum-dependent enzymes that can reduce N-hydroxylated substrates (e.g. N-hydroxyl-purines, amidoximes) are found in bacteria, plants and vertebrates. They are involved in the conversion of a wide range of N-hydroxylated organic compounds into their corresponding amines, and utilize various redox proteins (cytochrome b5, cyt b5 reductase, flavin reductase) to deliver reducing equivalents to the catalytic centre. Here we present catalytic electrochemistry of the bacterial enzyme YcbX from Escherichia coli utilizing the synthetic electron transfer mediator methyl viologen (MV2+). The electrochemically reduced form (MV+.) acts as an effective electron donor for YcbX. To immobilize YcbX on a glassy carbon electrode, a facile protein crosslinking approach was used with the crosslinker glutaraldehyde (GTA). The YcbX-modified electrode showed a catalytic response for the reduction of a broad range of N-hydroxylated substrates. The catalytic activity of YcbX was examined at different pH values exhibiting an optimum at pH 7.5 and a bell-shaped pH profile with deactivation through deprotonation (pKa1 9.1) or protonation (pKa2 6.1). Electrochemical simulation was employed to obtain new biochemical data for YcbX, in its reaction with methyl viologen and the organic substrates 6-N-hydroxylaminopurine (6-HAP) and benzamidoxime (BA).
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Affiliation(s)
- Palraj Kalimuthu
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane 4072, Australia
| | - Milena Baldauf
- Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Ahmed H Hassan
- Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Tobias Kruse
- Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia.
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Zapiter J, Harmer JR, Struwe M, Scheidig A, Clement B, Bernhardt PV. Enzyme Electrode Biosensors for N-Hydroxylated Prodrugs Incorporating the Mitochondrial Amidoxime Reducing Component. Anal Chem 2022; 94:9208-9215. [PMID: 35700342 DOI: 10.1021/acs.analchem.2c02232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human mitochondrial amidoxime reducing component 1 and 2 (mARC1 and mARC2) were immobilised on glassy carbon electrodes using the crosslinker glutaraldehyde. Voltammetry was performed in the presence of the artificial electron transfer mediator methyl viologen, whose redox potential lies negative of the enzymes' MoVI/V and MoV/IV redox potentials which were determined from optical spectroelectrochemical and EPR measurements. Apparent Michaelis constants obtained from catalytic limiting currents at various substrate concentrations were comparable to those previously reported in the literature from enzymatic assays. Kinetic parameters for benzamidoxime reduction were determined from cyclic voltammograms simulated using Digisim. pH dependence and stability of the enzyme electrode with time were also determined from limiting catalytic currents in saturating concentrations of benzamidoxime. The same electrode remained active after at least 9 days. Fabrication of this versatile and cost-effective biosensor is effective in screening new pharmaceutically important substrates and mARC inhibitors.
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Affiliation(s)
- Joan Zapiter
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, The University of Queensland, Brisbane 4072, Australia
| | - Michel Struwe
- Pharmazeutisches Institut, Universität Kiel, Gutenbergstraße 76, Kiel 24118, Germany.,Zoologisches Institut/Strukturbiologie, Am Botanischen Garten 11, Kiel 24118, Germany
| | - Axel Scheidig
- Zoologisches Institut/Strukturbiologie, Am Botanischen Garten 11, Kiel 24118, Germany
| | - Bernd Clement
- Pharmazeutisches Institut, Universität Kiel, Gutenbergstraße 76, Kiel 24118, Germany
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia
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8
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Kalimuthu P, Harmer JR, Baldauf M, Hassan AH, Kruse T, Bernhardt PV. Electrochemically driven catalysis of the bacterial molybdenum enzyme YiiM. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148523. [PMID: 34921810 DOI: 10.1016/j.bbabio.2021.148523] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/18/2021] [Accepted: 12/07/2021] [Indexed: 12/20/2022]
Abstract
The Mo-dependent enzyme YiiM enzyme from Escherichia coli is a member of the sulfite oxidase family and shares many similarities with the well-studied human mitochondrial amidoxime reducing component (mARC). We have investigated YiiM catalysis using electrochemical and spectroscopic methods. EPR monitored redox potentiometry found the active site redox potentials to be MoVI/V -0.02 V and MoV/IV -0.12 V vs NHE at pH 7.2. In the presence of methyl viologen as an electrochemically reduced electron donor, YiiM catalysis was studied with a range of potential substrates. YiiM preferentially reduces N-hydroxylated compounds such as hydroxylamines, amidoximes, N-hydroxypurines and N-hydroxyureas but shows little or no activity against amine-oxides or sulfoxides. The pH optimum for catalysis was 7.1 and a bell-shaped pH profile was found with pKa values of 6.2 and 8.1 either side of this optimum that are associated with protonation/deprotonations that modulate activity. Simulation of the experimental voltammetry elucidated kinetic parameters associated with YiiM catalysis with the substrates 6-hydroxyaminopurine and benzamidoxime.
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Affiliation(s)
- Palraj Kalimuthu
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, 4072, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane, 4072, Australia
| | - Milena Baldauf
- Department of Plant Biology, Technische Universitaet Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Ahmed H Hassan
- Department of Plant Biology, Technische Universitaet Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Tobias Kruse
- Department of Plant Biology, Technische Universitaet Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, 4072, Australia.
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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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Leimkühler S. The biosynthesis of the molybdenum cofactors in Escherichia coli. Environ Microbiol 2020; 22:2007-2026. [PMID: 32239579 DOI: 10.1111/1462-2920.15003] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/29/2022]
Abstract
The biosynthesis of the molybdenum cofactor (Moco) is highly conserved among all kingdoms of life. In all molybdoenzymes containing Moco, the molybdenum atom is coordinated to a dithiolene group present in the pterin-based 6-alkyl side chain of molybdopterin (MPT). In general, the biosynthesis of Moco can be divided into four steps in in bacteria: (i) the starting point is the formation of the cyclic pyranopterin monophosphate (cPMP) from 5'-GTP, (ii) in the second step the two sulfur atoms are inserted into cPMP leading to the formation of MPT, (iii) in the third step the molybdenum atom is inserted into MPT to form Moco and (iv) in the fourth step bis-Mo-MPT is formed and an additional modification of Moco is possible with the attachment of a nucleotide (CMP or GMP) to the phosphate group of MPT, forming the dinucleotide variants of Moco. This review presents an update on the well-characterized Moco biosynthesis in the model organism Escherichia coli including novel discoveries from the recent years.
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Affiliation(s)
- Silke Leimkühler
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
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11
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Kozmin SG, Rogozin IB, Moore EA, Abney M, Schaaper RM, Pavlov YI. Comment on "A commensal strain of Staphylococcus epidermidis protects against skin neoplasia" by Nakatsuji et al. SCIENCE ADVANCES 2019; 5:eaaw3915. [PMID: 31535021 PMCID: PMC6739109 DOI: 10.1126/sciadv.aaw3915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 08/15/2019] [Indexed: 06/10/2023]
Abstract
A recent article in Science Advances described the striking discovery that the commensal Staphylococcus epidermidis strain MO34 displays antimicrobial and antitumor activities by producing a small molecule, identified as the nucleobase analog 6-N-hydroxylaminopurine (6-HAP). However, in contradiction to the literature, the authors claimed that 6-HAP is nonmutagenic and proposed that the toxic effect of 6-HAP results from its ability to inhibit, in its base form, DNA synthesis. To resolve the discrepancy, we proved by genetic experiments with bacteria and yeast that extracts of MO34 do contain a mutagenic compound whose effects are identical to chemically synthesized 6-HAP. The MO34 extract induced the same mutation spectrum as authentic 6-HAP. Notably, the toxic and mutagenic effects of both synthetic and MO34-derived 6-HAP depended on conversion to the corresponding nucleotide. The nucleobase 6-HAP does not inhibit DNA synthesis in vitro, and we conclude that 6-HAP exerts its biological activity when incorporated into DNA.
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Affiliation(s)
- Stanislav G. Kozmin
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Igor B. Rogozin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Elizabeth A. Moore
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mariah Abney
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
- University of Nebraska at Omaha, Omaha, NE, USA
| | - Roel M. Schaaper
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Youri I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
- Departments of Microbiology and Pathology, Biochemistry and Molecular Biology, Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, USA
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12
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Wang S, Alseekh S, Fernie AR, Luo J. The Structure and Function of Major Plant Metabolite Modifications. MOLECULAR PLANT 2019; 12:899-919. [PMID: 31200079 DOI: 10.1016/j.molp.2019.06.001] [Citation(s) in RCA: 190] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/27/2019] [Accepted: 06/04/2019] [Indexed: 05/23/2023]
Abstract
Plants produce a myriad of structurally and functionally diverse metabolites that play many different roles in plant growth and development and in plant response to continually changing environmental conditions as well as abiotic and biotic stresses. This metabolic diversity is, to a large extent, due to chemical modification of the basic skeletons of metabolites. Here, we review the major known plant metabolite modifications and summarize the progress that has been achieved and the challenges we are facing in the field. We focus on discussing both technical and functional aspects in studying the influences that various modifications have on biosynthesis, degradation, transport, and storage of metabolites, as well as their bioactivity and toxicity. Finally, we discuss some emerging insights into the evolution of metabolic pathways and metabolite functionality.
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Affiliation(s)
- Shouchuang Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou 572208, China
| | - Saleh Alseekh
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm 14476, Germany; Centre of Plant Systems Biology and Biotechnology, Plovdiv 4000, Bulgaria
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm 14476, Germany; Centre of Plant Systems Biology and Biotechnology, Plovdiv 4000, Bulgaria.
| | - Jie Luo
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou 572208, China; National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
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13
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Tejada-Jimenez M, Llamas A, Galván A, Fernández E. Role of Nitrate Reductase in NO Production in Photosynthetic Eukaryotes. PLANTS 2019; 8:plants8030056. [PMID: 30845759 PMCID: PMC6473468 DOI: 10.3390/plants8030056] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/20/2022]
Abstract
Nitric oxide is a gaseous secondary messenger that is critical for proper cell signaling and plant survival when exposed to stress. Nitric oxide (NO) synthesis in plants, under standard phototrophic oxygenic conditions, has long been a very controversial issue. A few algal strains contain NO synthase (NOS), which appears to be absent in all other algae and land plants. The experimental data have led to the hypothesis that molybdoenzyme nitrate reductase (NR) is the main enzyme responsible for NO production in most plants. Recently, NR was found to be a necessary partner in a dual system that also includes another molybdoenzyme, which was renamed NO-forming nitrite reductase (NOFNiR). This enzyme produces NO independently of the molybdenum center of NR and depends on the NR electron transport chain from NAD(P)H to heme. Under the circumstances in which NR is not present or active, the existence of another NO-forming system that is similar to the NOS system would account for NO production and NO effects. PII protein, which senses and integrates the signals of the C–N balance in the cell, likely has an important role in organizing cell responses. Here, we critically analyze these topics.
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Affiliation(s)
- Manuel Tejada-Jimenez
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Aurora Galván
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Emilio Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
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14
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From the Eukaryotic Molybdenum Cofactor Biosynthesis to the Moonlighting Enzyme mARC. Molecules 2018; 23:molecules23123287. [PMID: 30545001 PMCID: PMC6321594 DOI: 10.3390/molecules23123287] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/23/2018] [Accepted: 12/05/2018] [Indexed: 12/20/2022] Open
Abstract
All eukaryotic molybdenum (Mo) enzymes contain in their active site a Mo Cofactor (Moco), which is formed by a tricyclic pyranopterin with a dithiolene chelating the Mo atom. Here, the eukaryotic Moco biosynthetic pathway and the eukaryotic Moco enzymes are overviewed, including nitrate reductase (NR), sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and the last one discovered, the moonlighting enzyme mitochondrial Amidoxime Reducing Component (mARC). The mARC enzymes catalyze the reduction of hydroxylated compounds, mostly N-hydroxylated (NHC), but as well of nitrite to nitric oxide, a second messenger. mARC shows a broad spectrum of NHC as substrates, some are prodrugs containing an amidoxime structure, some are mutagens, such as 6-hydroxylaminepurine and some others, which most probably will be discovered soon. Interestingly, all known mARC need the reducing power supplied by different partners. For the NHC reduction, mARC uses cytochrome b5 and cytochrome b5 reductase, however for the nitrite reduction, plant mARC uses NR. Despite the functional importance of mARC enzymatic reactions, the structural mechanism of its Moco-mediated catalysis is starting to be revealed. We propose and compare the mARC catalytic mechanism of nitrite versus NHC reduction. By using the recently resolved structure of a prokaryotic MOSC enzyme, from the mARC protein family, we have modeled an in silico three-dimensional structure of a eukaryotic homologue.
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15
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Peng T, Xu Y, Zhang Y. Comparative genomics of molybdenum utilization in prokaryotes and eukaryotes. BMC Genomics 2018; 19:691. [PMID: 30231876 PMCID: PMC6147048 DOI: 10.1186/s12864-018-5068-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 09/11/2018] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Molybdenum (Mo) is an essential micronutrient for almost all biological systems, which holds key positions in several enzymes involved in carbon, nitrogen and sulfur metabolism. In general, this transition metal needs to be coordinated to a unique pterin, thus forming a prosthetic group named molybdenum cofactor (Moco) at the catalytic sites of molybdoenzymes. The biochemical functions of many molybdoenzymes have been characterized; however, comprehensive analyses of the evolution of Mo metabolism and molybdoproteomes are quite limited. RESULTS In this study, we analyzed almost 5900 sequenced organisms to examine the occurrence of the Mo utilization trait at the levels of Mo transport system, Moco biosynthetic pathway and molybdoproteins in all three domains of life. A global map of Moco biosynthesis and molybdoproteins has been generated, which shows the most detailed understanding of Mo utilization in prokaryotes and eukaryotes so far. Our results revealed that most prokaryotes and all higher eukaryotes utilize Mo whereas many unicellular eukaryotes such as parasites and most yeasts lost the ability to use this metal. By characterizing the molybdoproteomes of all organisms, we found many new molybdoprotein-rich species, especially in bacteria. A variety of new domain fusions were detected for different molybdoprotein families, suggesting the presence of novel proteins that are functionally linked to molybdoproteins or Moco biosynthesis. Moreover, horizontal gene transfer event involving both the Moco biosynthetic pathway and molybdoproteins was identified. Finally, analysis of the relationship between environmental factors and Mo utilization showed new evolutionary trends of the Mo utilization trait. CONCLUSIONS Our data provide new insights into the evolutionary history of Mo utilization in nature.
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Affiliation(s)
- Ting Peng
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Guangdong Province, Shenzhen, 518060, China.,Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yinzhen Xu
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Guangdong Province, Shenzhen, 518060, China.,Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yan Zhang
- Shenzhen Key Laboratory of Marine Bioresources and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Guangdong Province, Shenzhen, 518060, China.
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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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17
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Namgung B, Kim JH, Song WS, Yoon SI. Crystal structure of the hydroxylaminopurine resistance protein, YiiM, and its putative molybdenum cofactor-binding catalytic site. Sci Rep 2018; 8:3304. [PMID: 29459651 PMCID: PMC5818509 DOI: 10.1038/s41598-018-21660-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 02/08/2018] [Indexed: 11/16/2022] Open
Abstract
The molybdenum cofactor (Moco) is a molybdenum-conjugated prosthetic group that is ubiquitously found in plants, animals, and bacteria. Moco is required for the nitrogen-reducing reaction of the Moco sulfurase C-terminal domain (MOSC) family. Despite the biological significance of MOSC proteins in the conversion of prodrugs and resistance against mutagens, their structural features and Moco-mediated catalysis mechanism have not been described in detail. YiiM is a MOSC protein that is involved in reducing mutagenic 6-N-hydroxylaminopurine to nontoxic adenine in bacteria. Here, we report two crystal structures of YiiM: one from Gram-positive Geobacillus stearothermophilus (gsYiiM) and the other from Gram-negative Escherichia coli (ecYiiM). Although gsYiiM and ecYiiM differ in oligomerization state and protein stability, both consist of three structural modules (a β-barrel and two α-helix bundles) and feature a cavity surrounded by the three modules. The cavity is characterized by positive electrostatic potentials and high sequence conservation. Moreover, the ecYiiM cavity houses a phosphate group, which emulates a part of Moco, and contains a highly reactive invariant cysteine residue. We thus propose that the cavity is the catalytic site where Moco binds and the substrate is reduced. Moreover, our comparative structural analysis highlights the common but distinct structural features of MOSC proteins.
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Affiliation(s)
- Byeol Namgung
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Jee-Hyeon Kim
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Wan Seok Song
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Sung-Il Yoon
- Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea. .,Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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18
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Llamas A, Chamizo-Ampudia A, Tejada-Jimenez M, Galvan A, Fernandez E. The molybdenum cofactor enzyme mARC: Moonlighting or promiscuous enzyme? Biofactors 2017; 43:486-494. [PMID: 28497908 DOI: 10.1002/biof.1362] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/20/2017] [Accepted: 03/28/2017] [Indexed: 12/13/2022]
Abstract
Molybdenum (Mo) is present in the active center of eukaryotic enzymes as a tricyclic pyranopterin chelate compound forming the Mo Cofactor (Moco). Four Moco containing enzymes are known in eukaryotes, nitrate reductase (NR), sulfite oxidase (SO), xanthine oxidoreductase (XOR), and aldehyde oxidase (AO). A fifth Moco enzyme has been recently identified. Because of the ability of this enzyme to convert by reduction several amidoximes prodrugs into their active amino forms, it was named mARC (mitochondrial Amidoxime Reducing Component). This enzyme is also able to catalyze the reduction of a broad range of N-hydroxylated compounds (NHC) as the base analogue 6-hydroxylaminopurine (HAP), as well as nitrite to nitric oxide (NO). All the mARC proteins need reducing power that is supplied by other proteins. The human and plants mARC proteins require a Cytochrome b5 (Cytb5) and a Cytochrome b5 reductase (Cytb5-R) to form an electron transfer chain from NADH to the NHC. Recently, plant mARC proteins were shown to be implicated in the reduction of nitrite to NO, and it was proposed that the electrons required for the reaction were supplied by NR instead of Cytochrome b5 components. This newly characterized mARC activity was termed NO Forming Nitrite Reductase (NOFNiR). Moonlighting proteins form a special class of multifunctional enzymes that can perform more than one function; if the extra function is not physiologically relevant, they are called promiscuous enzymes. In this review, we summarize the current knowledge on the mARC protein, and we propose that mARC is a new moonlighting enzyme. © 2017 BioFactors, 43(4):486-494, 2017.
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Affiliation(s)
- Angel Llamas
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Alejandro Chamizo-Ampudia
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Manuel Tejada-Jimenez
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Aurora Galvan
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Emilio Fernandez
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
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19
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Study of Different Variants of Mo Enzyme crARC and the Interaction with Its Partners crCytb5-R and crCytb5-1. Int J Mol Sci 2017; 18:ijms18030670. [PMID: 28335548 PMCID: PMC5372681 DOI: 10.3390/ijms18030670] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/07/2017] [Accepted: 03/10/2017] [Indexed: 12/30/2022] Open
Abstract
The mARC (mitochondrial Amidoxime Reducing Component) proteins are recently discovered molybdenum (Mo) Cofactor containing enzymes. They are involved in the reduction of several N-hydroxylated compounds (NHC) and nitrite. Some NHC are prodrugs containing an amidoxime structure or mutagens such as 6-hydroxylaminopurine (HAP). We have studied this protein in the green alga Chlamydomonas reinhardtii (crARC). Interestingly, all the ARC proteins need the reducing power supplied by other proteins. It is known that crARC requires a cytochrome b₅ (crCytb5-1) and a cytochrome b₅ reductase (crCytb5-R) that form an electron transport chain from NADH to the substrates. Here, we have investigated NHC reduction by crARC, the interaction with its partners and the function of important conserved amino acids. Interactions among crARC, crCytb5-1 and crCytb5-R have been studied by size-exclusion chromatography. A protein complex between crARC, crCytb5-1 and crCytb5-R was identified. Twelve conserved crARC amino acids have been substituted by alanine by in vitro mutagenesis. We have determined that the amino acids D182, F210 and R276 are essential for NHC reduction activity, R276 is important and F210 is critical for the Mo Cofactor chelation. Finally, the crARC C-termini were shown to be involved in protein aggregation or oligomerization.
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20
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Chamizo-Ampudia A, Sanz-Luque E, Llamas A, Galvan A, Fernandez E. Nitrate Reductase Regulates Plant Nitric Oxide Homeostasis. TRENDS IN PLANT SCIENCE 2017; 22:163-174. [PMID: 28065651 DOI: 10.1016/j.tplants.2016.12.001] [Citation(s) in RCA: 220] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/16/2016] [Accepted: 12/04/2016] [Indexed: 05/18/2023]
Abstract
Nitrate reductase (NR) is a key enzyme for nitrogen acquisition by plants, algae, yeasts, and fungi. Nitrate, its main substrate, is required for signaling and is widely distributed in diverse tissues in plants. In addition, NR has been proposed as an important enzymatic source of nitric oxide (NO). Recently, NR has been shown to play a role in NO homeostasis by supplying electrons from NAD(P)H through its diaphorase/dehydrogenase domain both to a truncated hemoglobin THB1, which scavenges NO by its dioxygenase activity, and to the molybdoenzyme NO-forming nitrite reductase (NOFNiR) that is responsible for NO synthesis from nitrite. We review how NR may play a central role in plant biology by controlling the amounts of NO, a key signaling molecule in plant cells.
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Affiliation(s)
- Alejandro Chamizo-Ampudia
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain
| | - Emanuel Sanz-Luque
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain; Present address: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Angel Llamas
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain
| | - Aurora Galvan
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain
| | - Emilio Fernandez
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain.
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21
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Chamizo-Ampudia A, Sanz-Luque E, Llamas Á, Ocaña-Calahorro F, Mariscal V, Carreras A, Barroso JB, Galván A, Fernández E. A dual system formed by the ARC and NR molybdoenzymes mediates nitrite-dependent NO production in Chlamydomonas. PLANT, CELL & ENVIRONMENT 2016; 39:2097-107. [PMID: 26992087 DOI: 10.1111/pce.12739] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 05/20/2023]
Abstract
Nitric oxide (NO) is a relevant signal molecule involved in many plant processes. However, the mechanisms and proteins responsible for its synthesis are scarcely known. In most photosynthetic organisms NO synthases have not been identified, and Nitrate Reductase (NR) has been proposed as the main enzymatic NO source, a process that in vitro is also catalysed by other molybdoenzymes. By studying transcriptional regulation, enzyme approaches, activity assays with in vitro purified proteins and in vivo and in vitro NO determinations, we have addressed the role of NR and Amidoxime Reducing Component (ARC) in the NO synthesis process. N\R and ARC were intimately related both at transcriptional and activity level. Thus, arc mutants showed high NIA1 (NR gene) expression and NR activity. Conversely, mutants without active NR displayed an increased ARC expression in nitrite medium. Our results with nia1 and arc mutants and with purified enzymes support that ARC catalyses the NO production from nitrite taking electrons from NR and not from Cytb5-1/Cytb5-Reductase, the component partners previously described for ARC (proposed as NOFNiR, Nitric Oxide-Forming Nitrite Reductase). This NR-ARC dual system would be able to produce NO in the presence of nitrate, condition under which NR is unable to do it.
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Affiliation(s)
- Alejandro Chamizo-Ampudia
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Emanuel Sanz-Luque
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Ángel Llamas
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Francisco Ocaña-Calahorro
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Vicente Mariscal
- Institute of Plant Biochemistry and Photosynthesis, C.S.I.C. and University of Sevilla, Américo Vespucio 49, Sevilla, 41092, Spain
| | - Alfonso Carreras
- Group of Biochemistry and Cell Signaling in Nitric Oxide. Department of Biochemistry and Molecular Biology, Campus 'Las Lagunillas', E-23071, University of Jaén, Jaén, Spain
| | - Juan B Barroso
- Group of Biochemistry and Cell Signaling in Nitric Oxide. Department of Biochemistry and Molecular Biology, Campus 'Las Lagunillas', E-23071, University of Jaén, Jaén, Spain
| | - Aurora Galván
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Emilio Fernández
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain.
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22
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Bay DC, Chan CS, Turner RJ. NarJ subfamily system specific chaperone diversity and evolution is directed by respiratory enzyme associations. BMC Evol Biol 2015; 15:110. [PMID: 26067063 PMCID: PMC4464133 DOI: 10.1186/s12862-015-0412-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 06/04/2015] [Indexed: 12/04/2022] Open
Abstract
Background Redox enzyme maturation proteins (REMPs) describe a diverse family of prokaryotic chaperones involved in the biogenesis of anaerobic complex iron sulfur molybdoenzyme (CISM) respiratory systems. Many REMP family studies have focused on NarJ subfamily members from Escherichia coli: NarJ, NarW, DmsD, TorD and YcdY. The aim of this bioinformatics study was to expand upon the evolution, distribution and genetic association of these 5 REMP members within 130 genome sequenced taxonomically diverse species representing 324 Prokaryotic sequences. NarJ subfamily member diversity was examined at the phylum-species level and at the amino acid/nucleotide level to determine how close their genetic associations were between their respective CISM systems within phyla. Results This study revealed that NarJ members possessed unique motifs that distinguished Gram-negative from Gram-positive/Archaeal species and identified a strict genetic association with its nitrate reductase complex (narGHI) operon compared to all other members. NarW appears to be found specifically in Gammaproteobacteria. DmsD also showed close associations with the dimethylsulfoxide reductase (dmsABC) operon compared to TorD. Phylogenetic analysis revealed that YcdY has recently evolved from DmsD and that YcdY has likely diverged into 2 subfamilies linked to Zn- dependent alkaline phosphatase (ycdX) operons and a newly identified operon containing part of Zn-metallopeptidase FtsH complex component (hflC) and NADH-quinone dehydrogenase (mdaB). TorD demonstrated the greatest diversity in operon association. TorD was identifed within operons from either trimethylamine-N-oxide reductase (torAC) or formate dehydrogenase (fdhGHI), where each type of TorD had a unique motif. Additionally a subgroup of dmsD and torD members were also linked to operons with biotin sulfoxide (bisC) and polysulfide reductase (nrfD) indicating a potential role in the maturation of diverse CISM. Conclusion Examination of diverse prokaryotic NarJ subfamily members demonstrates that the evolution and genetic association of each member is uniquely biased by its CISM operon association. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0412-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Denice C Bay
- Department of Biological Sciences, University of Calgary, Rm 156 Biological Science Bldg., 2500 University Dr. NW, Calgary, T2N 1 N4, AB, Canada.
| | - Catherine S Chan
- Department of Biological Sciences, University of Calgary, Rm 156 Biological Science Bldg., 2500 University Dr. NW, Calgary, T2N 1 N4, AB, Canada.
| | - Raymond J Turner
- Department of Biological Sciences, University of Calgary, Rm 156 Biological Science Bldg., 2500 University Dr. NW, Calgary, T2N 1 N4, AB, Canada.
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23
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Plitzko B, Havemeyer A, Kunze T, Clement B. The pivotal role of the mitochondrial amidoxime reducing component 2 in protecting human cells against apoptotic effects of the base analog N6-hydroxylaminopurine. J Biol Chem 2015; 290:10126-35. [PMID: 25713076 DOI: 10.1074/jbc.m115.640052] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Indexed: 12/27/2022] Open
Abstract
N-Hydroxylated nucleobases and nucleosides as N-hydroxylaminopurine (HAP) or N-hydroxyadenosine (HAPR) may be generated endogenously in the course of cell metabolism by cytochrome P450, by oxidative stress or by a deviating nucleotide biosynthesis. These compounds have shown to be toxic and mutagenic for procaryotic and eucaryotic cells. For DNA replication fidelity it is therefore of great importance that organisms exhibit effective mechanisms to remove such non-canonical base analogs from DNA precursor pools. In vitro, the molybdoenzymes mitochondrial amidoxime reducing component 1 and 2 (mARC1 and mARC2) have shown to be capable of reducing N-hydroxylated base analogs and nucleoside analogs to the corresponding canonical nucleobases and nucleosides upon reconstitution with the electron transport proteins cytochrome b5 and NADH-cytochrome b5 reductase. By RNAi-mediated down-regulation of mARC in human cell lines the mARC-dependent N-reductive detoxication of HAP in cell metabolism could be demonstrated. For HAPR, on the other hand, the reduction to adenosine seems to be of less significance in the detoxication pathway of human cells as HAPR is primarily metabolized to inosine by direct dehydroxylamination catalyzed by adenosine deaminase. Furthermore, the effect of mARC knockdown on sensitivity of human cells to HAP was examined by flow cytometric quantification of apoptotic cell death and detection of poly (ADP-ribose) polymerase (PARP) cleavage. mARC2 was shown to protect HeLa cells against the apoptotic effects of the base analog, whereas the involvement of mARC1 in reductive detoxication of HAP does not seem to be pivotal.
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Affiliation(s)
- Birte Plitzko
- From the Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
| | - Antje Havemeyer
- From the Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
| | - Thomas Kunze
- From the Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
| | - Bernd Clement
- From the Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
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24
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The mammalian molybdenum enzymes of mARC. J Biol Inorg Chem 2014; 20:265-75. [PMID: 25425164 DOI: 10.1007/s00775-014-1216-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 11/11/2014] [Indexed: 01/14/2023]
Abstract
The "mitochondrial amidoxime reducing component" (mARC) is the most recently discovered molybdenum-containing enzyme in mammals. All mammalian genomes studied to date contain two mARC genes: MARC1 and MARC2. The proteins encoded by these genes are mARC-1 and mARC-2 and represent the simplest form of eukaryotic molybdenum enzymes, only binding the molybdenum cofactor. In the presence of NADH, mARC proteins exert N-reductive activity together with the two electron transport proteins cytochrome b5 type B and NADH cytochrome b5 reductase. This enzyme system is capable of reducing a great variety of N-hydroxylated substrates. It plays a decisive role in the activation of prodrugs containing an amidoxime structure, and in detoxification pathways, e.g., of N-hydroxylated purine and pyrimidine bases. It belongs to a group of drug metabolism enzymes, in particular as a counterpart of P450 formed N-oxygenated metabolites. Its physiological relevance, on the other hand, is largely unknown. The aim of this article is to summarize our current knowledge of these proteins with a special focus on the mammalian enzymes and their N-reductive activity.
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - James Hall
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
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Andreae CA, Titball RW, Butler CS. Influence of the molybdenum cofactor biosynthesis on anaerobic respiration, biofilm formation and motility in Burkholderia thailandensis. Res Microbiol 2013; 165:41-9. [PMID: 24239959 DOI: 10.1016/j.resmic.2013.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/29/2013] [Indexed: 11/16/2022]
Abstract
Burkholderia thailandensis is closely related to Burkholderia pseudomallei, a bacterial pathogen and the causative agent of melioidosis. B. pseudomallei can survive and persist within a hypoxic environment for up to one year and has been shown to grow anaerobically in the presence of nitrate. Currently, little is known about the role of anaerobic respiration in pathogenesis of melioidosis. Using B. thailandensis as a model, a library of 1344 transposon mutants was created to identify genes required for anaerobic nitrate respiration. One transposon mutant (CA01) was identified with an insertion in BTH_I1704 (moeA), a gene required for the molybdopterin biosynthetic pathway. This pathway is involved in the synthesis of a molybdopterin cofactor required for a variety of molybdoenzymes, including nitrate reductase. Disruption of molybdopterin biosynthesis prevented growth under anaerobic conditions, when using nitrate as the sole terminal electron acceptor. Defects in anaerobic respiration, nitrate reduction, motility and biofilm formation were observed for CA01. Mutant complementation with pDA-17:BTH_I1704 was able to restore anaerobic growth on nitrate, nitrate reductase activity and biofilm formation, but did not restore motility. This study highlights the potential importance of molybdoenzyme-dependent anaerobic respiration in the survival and virulence of B. thailandensis.
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Affiliation(s)
- Clio A Andreae
- College of Life and Environmental Science, University of Exeter, Stocker Road, Exeter, Devon EX4 4QD, United Kingdom.
| | - Richard W Titball
- College of Life and Environmental Science, University of Exeter, Stocker Road, Exeter, Devon EX4 4QD, United Kingdom.
| | - Clive S Butler
- College of Life and Environmental Science, University of Exeter, Stocker Road, Exeter, Devon EX4 4QD, United Kingdom.
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A critical role for the putative NCS2 nucleobase permease YjcD in the sensitivity of Escherichia coli to cytotoxic and mutagenic purine analogs. mBio 2013; 4:e00661-13. [PMID: 24169576 PMCID: PMC3809563 DOI: 10.1128/mbio.00661-13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The base analogs 6-N-hydroxylaminopurine (HAP) and 2-amino-HAP (AHAP) are potent mutagens in bacteria and eukaryotic organisms. Previously, we demonstrated that a defect in the Escherichia coli ycbX gene, encoding a molybdenum cofactor-dependent oxidoreductase, dramatically enhances sensitivity to the toxic and mutagenic action of these agents. In the present study, we describe the discovery and properties of a novel suppressor locus, yjcD, that strongly reduces the HAP sensitivity of the ycbX strain. Suppressor effects are also observed for other purine analogs, like AHAP, 6-mercaptopurine, 6-thioguanine, and 2-aminopurine. In contrast, the yjcD defect did not affect the sensitivity to the pyrimidine analog 5-fluorouracil. Homology searches have predicted that yjcD encodes a putative permease of the NCS2 family of nucleobase transporters. We further investigated the effects of inactivation of all other members of the NCS2 family, XanQ, XanP, PurP, UacT, UraA, RutG, YgfQ, YicO, and YbbY, and of the NCS1 family nucleobase permeases CodB and YbbW. None of these other defects significantly affected sensitivity to either HAP or AHAP. The combined data strongly suggest that YjcD is the primary importer for modified purine bases. We also present data showing that this protein may, in fact, also be a principal permease involved in transport of the normal purines guanine, hypoxanthine, and/or xanthine. Nucleotide metabolism is a critical aspect of the overall metabolism of the cell, as it is central to the core processes of RNA and DNA synthesis. At the same time, nucleotide metabolism can be subverted by analogs of the normal DNA or RNA bases, leading to highly toxic and mutagenic effects. Thus, understanding how cells process both normal and modified bases is of fundamental importance. This work describes a novel suppressor of the toxicity of certain modified purine bases in the bacterium Escherichia coli. This suppressor encodes a putative high-affinity nucleobase transporter that mediates the import of the modified purine bases. It is also a likely candidate for the long-sought high-affinity importer for the normal purines, like guanine and hypoxanthine.
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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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Gall AD, Gall A, Moore AC, Aune MK, Heid S, Mori A, Burgis NE. Analysis of human ITPase nucleobase specificity by site-directed mutagenesis. Biochimie 2013; 95:1711-21. [PMID: 23770441 DOI: 10.1016/j.biochi.2013.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 05/23/2013] [Indexed: 02/07/2023]
Abstract
Inosine triphosphate (ITP) pyrophosphohydrolase, or ITPase, is an intracellular enzyme that is responsible for the hydrolysis of the acidic anhydride bond between the alpha and beta phosphates in ITP, and other noncanonical nucleoside triphosphates, producing the corresponding nucleoside monophosphate and pyrophosphate. This activity protects the cell by preventing noncanonical nucleoside triphosphates from accumulating in (deoxy) nucleoside triphosphate ((d)NTP) pools and/or being integrated into nucleic acids. This enzyme is encoded by the ITPA gene in mammals. It has been reported that Itpa homozygous-null knock-out mice die before weaning and have gross cardiac abnormalities. Additionally, certain variations in the human ITPA gene have been linked to adverse reactions to the immunosuppressive prodrugs azathioprine and 6-mercaptopurine and protection against ribavirin-induced hemolytic anemia. These drugs are bioactivated to form noncanonical nucleoside triphosphates. Human ITPase enzymes engineered to modulate nucleobase specificity may be valuable tools for studying the role of ITPase in heart development and drug metabolism or developing gain-of-function mutants or inhibitory molecules. Based on x-ray crystallography and amino acid sequence data, a panel of putative human ITPase nucleobase specificity mutants has been generated. We targeted eight highly conserved amino acid positions within the ITPase sequence that correspond to amino acids predicted to directly interact with the nucleobase or help organize the nucleobase binding pocket. The ability of the mutants to protect against exogenous and endogenous noncanonical purines was tested with two Escherichia coli complementation assays. Nucleobase specificity of the mutants was investigated with an in vitro biochemical assay using ITP, GTP and ATP as substrates. This methodology allowed us to identify gain-of-function mutants and categorize the eight amino acid positions according to their ability to protect against noncanonical purines as follows: Glu-22, Trp-151 and Arg-178, essential for protection; Phe-149, Asp-152, Lys-172 and Ser-176, intermediate protection; His-177, dispensable for protection against noncanonical purines.
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Affiliation(s)
- Amanda D Gall
- Department of Chemistry and Biochemistry, Eastern Washington University, 226 Science Building, Cheney, WA 99004, USA
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Simone PD, Struble LR, Kellezi A, Brown CA, Grabow CE, Khutsishvili I, Marky LA, Pavlov YI, Borgstahl GE. The human ITPA polymorphic variant P32T is destabilized by the unpacking of the hydrophobic core. J Struct Biol 2013; 182:197-208. [PMID: 23528839 PMCID: PMC4212276 DOI: 10.1016/j.jsb.2013.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 03/11/2013] [Accepted: 03/13/2013] [Indexed: 01/24/2023]
Abstract
Inosine triphosphate pyrophosphatase (ITPA), a key enzyme involved in maintaining the purity of cellular nucleoside triphosphate pools, specifically recognizes inosine triphosphate and xanthosine triphosphate (including the deoxyribose forms) and detoxifies them by catalyzing the hydrolysis of a phosphoanhydride bond, releasing pyrophosphate. This prevents their inappropriate use as substrates in enzymatic reactions utilizing (d)ATP or (d)GTP. A human genetic polymorphism leads to the substitution of Thr for Pro32 (P32T) and causes ITPA deficiency in erythrocytes, with heterozygotes having on average 22.5% residual activity, and homozygotes having undetectable activity. This polymorphism has been implicated in modulating patients' response to mercaptopurines and ribavirin. Human fibroblasts containing this variant have elevated genomic instability upon treatment with base analogs. We find that the wild-type and P32T forms are dimeric in solution and in the crystal structure. This abolishes the previous speculation that the P32T change disrupts dimerization as a mechanism of inactivation. The only difference in structure from the wild-type protein is that the area surrounding Thr32 is disrupted. Phe31 is flipped from the hydrophobic core out into the solvent, leaving a hole in the hydrophobic core of the protein which likely accounts for the reduced thermal stability of P32T ITPA and ultimately leads to its susceptibility to degradation in human cells. Circular dichroism and thermal denaturation studies confirm these structural results. We propose that the dimer of P32T variant subunit with wild-type subunit is degraded in cells similarly to the P32T homodimer explaining the level of loss of ITPA activity in heterozygotes.
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Affiliation(s)
- Peter D. Simone
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA
| | - Lucas R. Struble
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Admir Kellezi
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA
| | - Carrie A. Brown
- Department of Chemistry, Wayne State College, Wayne, NE 68787, USA
| | - Corinn E. Grabow
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA
| | - Irine Khutsishvili
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Luis A. Marky
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Youri I. Pavlov
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Genetics, St-Petersburg University, St-Petersburg 199034, Russia
| | - Gloria E.O. Borgstahl
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
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32
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Metabolite damage and its repair or pre-emption. Nat Chem Biol 2013; 9:72-80. [PMID: 23334546 DOI: 10.1038/nchembio.1141] [Citation(s) in RCA: 218] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 11/13/2012] [Indexed: 01/25/2023]
Abstract
It is increasingly evident that metabolites suffer various kinds of damage, that such damage happens in all organisms and that cells have dedicated systems for damage repair and containment. First, chemical biology is demonstrating that diverse metabolites are damaged by side reactions of 'promiscuous' enzymes or by spontaneous chemical reactions, that the products are useless or toxic and that the unchecked buildup of these products can be devastating. Second, genetic and genomic evidence from prokaryotes and eukaryotes is implicating a network of new, conserved enzymes that repair damaged metabolites or somehow pre-empt damage. Metabolite (that is, small-molecule) repair is analogous to macromolecule (DNA and protein) repair and seems from comparative genomic evidence to be equally widespread. Comparative genomics also implies that metabolite repair could be the function of many conserved protein families lacking known activities. How--and how well--cells deal with metabolite damage affects fields ranging from medical genetics to metabolic engineering.
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Abstract
A perspective is provided of recent advances in our understanding of molybdenum-containing enzymes other than nitrogenase, a large and diverse group of enzymes that usually (but not always) catalyze oxygen atom transfer to or from a substrate, utilizing a Mo=O group as donor or acceptor. An emphasis is placed on the diversity of protein structure and reaction catalyzed by each of the three major families of these enzymes.
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, 1643 Boyce Hall, Riverside, CA 92521, USA.
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34
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Kappler U, Nouwens AS. The molybdoproteome of Starkeya novella – insights into the diversity and functions of molybdenum containing proteins in response to changing growth conditions. Metallomics 2013; 5:325-34. [DOI: 10.1039/c2mt20230a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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35
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Tejada-Jiménez M, Chamizo-Ampudia A, Galván A, Fernández E, Llamas Á. Molybdenum metabolism in plants. Metallomics 2013; 5:1191-203. [DOI: 10.1039/c3mt00078h] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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36
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Abstract
Biological trace metals are needed in small quantities, but used by all living organisms. They are employed in key cellular functions in a variety of biological processes, resulting in the various degree of dependence of organisms on metals. Most effort in the field has been placed on experimental studies of metal utilization pathways and metal-dependent proteins. On the other hand, systemic level analyses of metalloproteomes (or metallomes) have been limited for most metals. In this chapter, we focus on the recent advances in comparative genomics, which provides many insights into evolution and function of metal utilization. These studies suggested that iron and zinc are widely used in biology (presumably by all organisms), whereas some other metals such as copper, molybdenum, nickel, and cobalt, show scattered occurrence in various groups of organisms. For these metals, most user proteins are well characterized and their dependence on a specific element is evolutionarily conserved. We also discuss evolutionary dynamics of the dependence of user proteins on different metals. Overall, comparative genomics analysis of metallomes provides a foundation for the systemic level understanding of metal utilization as well as for investigating the general features, functions, and evolutionary dynamics of metal use in the three domains of life.
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Waisertreiger ISR, Liston VG, Menezes MR, Kim HM, Lobachev KS, Stepchenkova EI, Tahirov TH, Rogozin IB, Pavlov YI. Modulation of mutagenesis in eukaryotes by DNA replication fork dynamics and quality of nucleotide pools. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:699-724. [PMID: 23055184 PMCID: PMC3893020 DOI: 10.1002/em.21735] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/13/2012] [Accepted: 08/15/2012] [Indexed: 06/01/2023]
Abstract
The rate of mutations in eukaryotes depends on a plethora of factors and is not immediately derived from the fidelity of DNA polymerases (Pols). Replication of chromosomes containing the anti-parallel strands of duplex DNA occurs through the copying of leading and lagging strand templates by a trio of Pols α, δ and ϵ, with the assistance of Pol ζ and Y-family Pols at difficult DNA template structures or sites of DNA damage. The parameters of the synthesis at a given location are dictated by the quality and quantity of nucleotides in the pools, replication fork architecture, transcription status, regulation of Pol switches, and structure of chromatin. The result of these transactions is a subject of survey and editing by DNA repair.
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Affiliation(s)
- Irina S.-R. Waisertreiger
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Victoria G. Liston
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Miriam R. Menezes
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Hyun-Min Kim
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Kirill S. Lobachev
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Elena I. Stepchenkova
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
- Saint Petersburg Branch of Vavilov Institute of General Genetics, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
- Department of Genetics, Saint Petersburg University, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
| | - Tahir H. Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Igor B. Rogozin
- National Center for Biotechnology Information NLM, National Institutes of Health, Bethesda, MD 20894, U.S.A
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | - Youri. I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
- Department of Genetics, Saint Petersburg University, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
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Iobbi-Nivol C, Leimkühler S. Molybdenum enzymes, their maturation and molybdenum cofactor biosynthesis in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012. [PMID: 23201473 DOI: 10.1016/j.bbabio.2012.11.007] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Molybdenum cofactor (Moco) biosynthesis is an ancient, ubiquitous, and highly conserved pathway leading to the biochemical activation of molybdenum. Moco is the essential component of a group of redox enzymes, which are diverse in terms of their phylogenetic distribution and their architectures, both at the overall level and in their catalytic geometry. A wide variety of transformations are catalyzed by these enzymes at carbon, sulfur and nitrogen atoms, which include the transfer of an oxo group or two electrons to or from the substrate. More than 50 molybdoenzymes were identified in bacteria to date. In molybdoenzymes Mo is coordinated to a dithiolene group on the 6-alkyl side chain of a pterin called molybdopterin (MPT). The biosynthesis of Moco can be divided into four general steps in bacteria: 1) formation of the cyclic pyranopterin monophosphate, 2) formation of MPT, 3) insertion of molybdenum into molybdopterin to form Moco, and 4) additional modification of Moco with the attachment of GMP or CMP to the phosphate group of MPT, forming the dinucleotide variant of Moco. This review will focus on molybdoenzymes, the biosynthesis of Moco, and its incorporation into specific target proteins focusing on Escherichia coli. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
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Affiliation(s)
- Chantal Iobbi-Nivol
- Institut de Microbiologie de la Méditerranée, Aix Marseille Université, Marseille, France
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39
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Krompholz N, Krischkowski C, Reichmann D, Garbe-Schönberg D, Mendel RR, Bittner F, Clement B, Havemeyer A. The mitochondrial Amidoxime Reducing Component (mARC) is involved in detoxification of N-hydroxylated base analogues. Chem Res Toxicol 2012; 25:2443-50. [PMID: 22924387 DOI: 10.1021/tx300298m] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The "mitochondrial Amidoxime Reducing Component" (mARC) is the newly discovered fourth molybdenum enzyme in mammals. All hitherto analyzed mammals express two mARC proteins, referred to as mARC1 and mARC2. Together with their electron transport proteins cytochrome b(5) and NADH cytochrome b(5) reductase, they form a three-component enzyme system and catalyze the reduction of N-hydroxylated prodrugs. Here, we demonstrate the reductive detoxification of toxic and mutagenic N-hydroxylated nucleobases and their corresponding nucleosides by the mammalian mARC-containing enzyme system. The N-reductive activity was found in all tested tissues with the highest detectable conversion rates in liver, kidney, thyroid, and pancreas. According to the presumed localization, the N-reductive activity is most pronounced in enriched mitochondrial fractions. In vitro assays with the respective recombinant three-component enzyme system show that both mARC isoforms are able to reduce N-hydroxylated base analogues, with mARC1 representing the more efficient isoform. On the basis of the high specific activities with N-hydroxylated base analogues relative to other N-hydroxylated substrates, our data suggest that mARC proteins might be involved in protecting cellular DNA from misincorporation of toxic N-hydroxylated base analogues during replication by converting them to the correct purine or pyrimidine bases, respectively.
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Affiliation(s)
- Nina Krompholz
- Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Germany 24118
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40
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Menezes MR, Waisertreiger ISR, Lopez-Bertoni H, Luo X, Pavlov YI. Pivotal role of inosine triphosphate pyrophosphatase in maintaining genome stability and the prevention of apoptosis in human cells. PLoS One 2012; 7:e32313. [PMID: 22384212 PMCID: PMC3288088 DOI: 10.1371/journal.pone.0032313] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 01/25/2012] [Indexed: 12/22/2022] Open
Abstract
Pure nucleotide precursor pools are a prerequisite for high-fidelity DNA replication and the suppression of mutagenesis and carcinogenesis. ITPases are nucleoside triphosphate pyrophosphatases that clean the precursor pools of the non-canonical triphosphates of inosine and xanthine. The precise role of the human ITPase, encoded by the ITPA gene, is not clearly defined. ITPA is clinically important because a widespread polymorphism, 94C>A, leads to null ITPase activity in erythrocytes and is associated with an adverse reaction to thiopurine drugs. We studied the cellular function of ITPA in HeLa cells using the purine analog 6-N hydroxylaminopurine (HAP), whose triphosphate is also a substrate for ITPA. In this study, we demonstrate that ITPA knockdown sensitizes HeLa cells to HAP-induced DNA breaks and apoptosis. The HAP-induced DNA damage and cytotoxicity observed in ITPA knockdown cells are rescued by an overexpression of the yeast ITPase encoded by the HAM1 gene. We further show that ITPA knockdown results in elevated mutagenesis in response to HAP treatment. Our studies reveal the significance of ITPA in preventing base analog-induced apoptosis, DNA damage and mutagenesis in human cells. This implies that individuals with defective ITPase are predisposed to genome damage by impurities in nucleotide pools, which is drastically augmented by therapy with purine analogs. They are also at an elevated risk for degenerative diseases and cancer.
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Affiliation(s)
| | | | | | | | - Youri I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, Nebraska Medical Center, Omaha, Nebraska, United States of America
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41
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Neve EPA, Nordling Å, Andersson TB, Hellman U, Diczfalusy U, Johansson I, Ingelman-Sundberg M. Amidoxime reductase system containing cytochrome b5 type B (CYB5B) and MOSC2 is of importance for lipid synthesis in adipocyte mitochondria. J Biol Chem 2012; 287:6307-17. [PMID: 22203676 PMCID: PMC3307252 DOI: 10.1074/jbc.m111.328237] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 12/21/2011] [Indexed: 12/21/2022] Open
Abstract
Reduction of hydroxylamines and amidoximes is important for drug activation and detoxification of aromatic and heterocyclic amines. Such a reductase system was previously found to be of high activity in adipose tissue and liver, and furthermore, in vitro studies using recombinant truncated and purified enzymes suggested the participation of cytochrome b(5) reductase (CYB5R), cytochrome b(5) (CYB5), and molybdenum cofactor sulfurase C-terminal containing 1 and 2 (MOSC1 and -2). Here, we show that purified rat liver outer mitochondrial membrane contains high amidoxime reductase activity and that MOSC2 is exclusively localized to these membranes. Moreover, using the same membrane fraction, we could show direct binding of a radiolabeled benzamidoxime substrate to MOSC2. Following differentiation of murine 3T3-L1 cells into mature adipocytes, the MOSC2 levels as well as the amidoxime reductase activity were increased, indicating that the enzyme is highly regulated under lipogenic conditions. siRNA-mediated down-regulation of MOSC2 and the mitochondrial form of cytochrome b(5) type B (CYB5B) significantly inhibited the reductase activity in the differentiated adipocytes, whereas down-regulation of MOSC1, cytochrome b(5) type A (CYB5A), CYB5R1, CYB5R2, or CYB5R3 had no effect. Down-regulation of MOSC2 caused impaired lipid synthesis. These results demonstrate for the first time the direct involvement of MOSC2 and CYB5B in the amidoxime reductase activity in an intact cell system. We postulate the presence of a novel reductive enzyme system of importance for lipid synthesis that is exclusively localized to the outer mitochondrial membrane and is composed of CYB5B, MOSC2, and a third unknown component (a CYB5B reductase).
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Affiliation(s)
- Etienne P. A. Neve
- From the Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, SE-17177 Stockholm
| | - Åsa Nordling
- From the Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, SE-17177 Stockholm
| | - Tommy B. Andersson
- From the Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, SE-17177 Stockholm
- AstraZeneca Research and Development, Pepparedsleden 1, SE-431 83 Mölndal
| | - Ulf Hellman
- the Ludwig Institute for Cancer Research, Ltd., Uppsala Branch, SE-75123 Uppsala, and
| | - Ulf Diczfalusy
- the Department of Laboratory Medicine, Division of Clinical Chemistry, Karolinska Institutet, Karolinska University Hospital Huddinge, SE-141 86 Huddinge, Sweden
| | - Inger Johansson
- From the Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, SE-17177 Stockholm
| | - Magnus Ingelman-Sundberg
- From the Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, SE-17177 Stockholm
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Havemeyer A, Lang J, Clement B. The fourth mammalian molybdenum enzyme mARC: current state of research. Drug Metab Rev 2011; 43:524-39. [DOI: 10.3109/03602532.2011.608682] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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The Chlamydomonas reinhardtii molybdenum cofactor enzyme crARC has a Zn-dependent activity and protein partners similar to those of its human homologue. EUKARYOTIC CELL 2011; 10:1270-82. [PMID: 21803866 DOI: 10.1128/ec.05096-11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ARC (amidoxime reducing component) proteins are molybdenum cofactor (Moco) enzymes named hmARC1 and hmARC2 (human ARCs [hmARCs]) in humans and YcbX in Escherichia coli. They catalyze the reduction of a broad range of N-hydroxylated compounds (NHC) using reducing power supplied by other proteins. Some NHC are prodrugs or toxic compounds. YcbX contains a ferredoxin (Fd) domain and requires the NADPH flavin reductase CysJ to reduce NHC. In contrast, hmARCs lack the Fd domain and require a human cytochrome b5 (hCyt b5) and a human NADH Cyt b5 reductase (hCyt b5-R) to reduce NHC. The ARC proteins in the plant kingdom are uncharacterized. We demonstrate that Chlamydomonas reinhardtii mutants defective in Moco biosynthesis genes are sensitive to the NHC N(6)-hydroxylaminopurine (HAP). The Chlamydomonas reinhardtii ARC protein crARC has been purified and characterized. The six Chlamydomonas Fds were isolated, but none of them are required by crARC to reduce HAP. We have also purified and characterized five C. reinhardtii Cyt b5 (crCyt b5) and two flavin reductases, one that is NADPH dependent (crCysJ) and one that is NADH dependent (crCyt b5-R). The data show that crARC uses crCyt b5-1 and crCyt b5-R to reduce HAP. The crARC has a Zn-dependent activity, and the presence of Zn increases its V(max) more than 14-fold. In addition, all five cysteines of crARC were substituted by alanine, and we demonstrate that the fully conserved cysteine 252 is essential for both Moco binding and catalysis. Therefore, it is proposed that crARC belongs to the sulfite oxidase family of Moco enzymes.
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Llamas A, Tejada-Jiménez M, Fernández E, Galván A. Molybdenum metabolism in the alga Chlamydomonas stands at the crossroad of those in Arabidopsis and humans. Metallomics 2011; 3:578-90. [PMID: 21623427 DOI: 10.1039/c1mt00032b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Molybdenum (Mo) is a very scarce element whose function is fundamental in living beings within the active site of Mo-oxidoreductases, playing key roles in the metabolism of N, S, purines, hormone biosynthesis, transformation of drugs and xenobiotics, etc. In eukaryotes, each step from Mo acquisition until its incorporation into a biologically active molybdenum cofactor (Moco) together with the assembly of this Moco in Mo-enzymes is almost understood. The deficiency in function of a particular molybdoenzyme can be critical for the survival of the organism dependent on the pathway involved. However, incapacity in forming a functional Moco has a pleiotropic effect in the different processes involving this cofactor. A detailed overview of Mo metabolism: (a) specific transporters for molybdate, (b) the universal biosynthesis pathway for Moco from GTP, (c) Moco-carrier and Moco-binding proteins for Moco transfer and (d) Mo-enzymes, is analyzed in light of recent findings and three systems are compared, the unicellular microalga Chlamydomonas, the plant Arabidopsis and humans.
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Affiliation(s)
- Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Edif. Severo Ochoa, 14071 Córdoba, Spain.
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45
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Abstract
Recent progress in our understanding of the structural and catalytic properties of molybdenum-containing enzymes in eukaryotes is reviewed, along with aspects of the biosynthesis of the cofactor and its insertion into apoprotein.
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, Riverside, CA 92521
| | - Takeshi Nishino
- Department of Biochemistry and Molecular Biology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, Japan and Department of Biochemistry, University of California, Riverside, CA 92521
| | - Florian Bittner
- Department of Plant Biology, Technical University of Braunschweig, 38023 Braunschweig, Germany
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46
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Abstract
The trace element molybdenum (Mo) is the catalytic component of important enzymes involved in global nitrogen, sulfur, and carbon metabolism in both prokaryotes and eukaryotes. With the exception of nitrogenase, Mo is complexed by a pterin compound thus forming the biologically active molybdenum cofactor (Moco) at the catalytic sites of molybdoenzymes. The physiological roles and biochemical functions of many molybdoenzymes have been characterized. However, our understanding of the occurrence and evolution of Mo utilization is limited. This article focuses on recent advances in comparative genomics of Mo utilization in the three domains of life. We begin with a brief introduction of Mo transport systems, the Moco biosynthesis pathway, the role of posttranslational modifications, and enzymes that utilize Mo. Then, we proceed to recent computational and comparative genomics studies of Mo utilization, including a discussion on novel Moco-binding proteins that contain the C-terminal domain of the Moco sulfurase and that are suggested to represent a new family of molybdoenzymes. As most molybdoenzymes need additional cofactors for their catalytic activity, we also discuss interactions between Mo metabolism and other trace elements and finish with an analysis of factors that may influence evolution of Mo utilization.
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Affiliation(s)
- Yan Zhang
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, MA 02115, United States
| | - Steffen Rump
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, MA 02115, United States
| | - Vadim N. Gladyshev
- Division of Genetics, Department of Medicine, Brigham & Women’s Hospital and Harvard Medical School, Boston, MA 02115, United States
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47
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Identification of Escherichia coli ZapC (YcbW) as a component of the division apparatus that binds and bundles FtsZ polymers. J Bacteriol 2011; 193:1393-404. [PMID: 21216997 DOI: 10.1128/jb.01245-10] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Assembly of the cell division apparatus in bacteria starts with formation of the Z ring on the cytoplasmic face of the membrane. This process involves the accumulation of FtsZ polymers at midcell and their interaction with several FtsZ-binding proteins that collectively organize the polymers into a membrane-associated ring-like configuration. Three such proteins, FtsA, ZipA, and ZapA, have previously been identified in Escherichia coli. FtsA and ZipA are essential membrane-associated division proteins that help connect FtsZ polymers with the inner membrane. ZapA is a cytoplasmic protein that is not required for the fission process per se but contributes to its efficiency, likely by promoting lateral interactions between FtsZ protofilaments. We report the identification of YcbW (ZapC) as a fourth FtsZ-binding component of the Z ring in E. coli. Binding of ZapC promotes lateral interactions between FtsZ polymers and suppresses FtsZ GTPase activity. This and additional evidence indicate that, like ZapA, ZapC is a nonessential Z-ring component that contributes to the efficiency of the division process by stabilizing the polymeric form of FtsZ.
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48
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The role of system-specific molecular chaperones in the maturation of molybdoenzymes in bacteria. Biochem Res Int 2010; 2011:850924. [PMID: 21151514 PMCID: PMC2997495 DOI: 10.1155/2011/850924] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 08/31/2010] [Indexed: 11/18/2022] Open
Abstract
Biogenesis of prokaryotic molybdoenzymes is a complex process with the final step representing the insertion of a matured molybdenum cofactor (Moco) into a folded apoenzyme. Usually, specific chaperones of the XdhC family are required for the maturation of molybdoenzymes of the xanthine oxidase family in bacteria. Enzymes of the xanthine oxidase family are characterized to contain an equatorial sulfur ligand at the molybdenum center of Moco. This sulfur ligand is inserted into Moco while bound to the XdhC-like protein and before its insertion into the target enzyme. In addition, enzymes of the xanthine oxidase family bind either the molybdopterin (Mo-MPT) form of Moco or the modified molybdopterin cytosine dinucleotide cofactor (MCD). In both cases, only the matured cofactor is inserted by a proofreading process of XdhC. The roles of these specific XdhC-like chaperones during the biogenesis of enzymes of the xanthine oxidase family in bacteria are described.
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49
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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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50
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Waisertreiger ISR, Menezes MR, Randazzo J, Pavlov YI. Elevated Levels of DNA Strand Breaks Induced by a Base Analog in the Human Cell Line with the P32T ITPA Variant. J Nucleic Acids 2010; 2010. [PMID: 20936128 PMCID: PMC2948936 DOI: 10.4061/2010/872180] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 07/11/2010] [Indexed: 12/29/2022] Open
Abstract
Base analogs are powerful antimetabolites and dangerous mutagens generated endogenously by oxidative stress, inflammation, and aberrant nucleotide biosynthesis. Human inosine triphosphate pyrophosphatase (ITPA) hydrolyzes triphosphates of noncanonical purine bases (i.e., ITP, dITP, XTP, dXTP, or their mimic: 6-hydroxyaminopurine (HAP) deoxynucleoside triphosphate) and thus regulates nucleotide pools and protects cells from DNA damage. We demonstrate that the model purine base analog HAP induces DNA breaks in human cells and leads to elevation of levels of ITPA. A human polymorphic allele of the ITPA, 94C->A encodes for the enzyme with a P32T amino-acid change and leads to accumulation of nonhydrolyzed ITP. The polymorphism has been associated with adverse reaction to purine base-analog drugs. The level of both spontaneous and HAP-induced DNA breaks is elevated in the cell line with the ITPA P32T variant. The results suggested that human ITPA plays a pivotal role in the protection of DNA from noncanonical purine base analogs.
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Affiliation(s)
- Irina S-R Waisertreiger
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA
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