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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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2
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Rixen S, Indorf PM, Kubitza C, Struwe MA, Klopp C, Scheidig AJ, Kunze T, Clement B. Reduction of Hydrogen Peroxide by Human Mitochondrial Amidoxime Reducing Component Enzymes. Molecules 2023; 28:6384. [PMID: 37687214 PMCID: PMC10489706 DOI: 10.3390/molecules28176384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/23/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
The mitochondrial amidoxime reducing component (mARC) is a human molybdoenzyme known to catalyze the reduction of various N-oxygenated substrates. The physiological function of mARC enzymes, however, remains unknown. In this study, we examine the reduction of hydrogen peroxide (H2O2) by the human mARC1 and mARC2 enzymes. Furthermore, we demonstrate an increased sensitivity toward H2O2 for HEK-293T cells with an MTARC1 knockout, which implies a role of mARC enzymes in the cellular response to oxidative stress. H2O2 is a reactive oxygen species (ROS) formed in all living cells involved in many physiological processes. Furthermore, H2O2 constitutes the first mARC substrate without a nitrogen-oxygen bond, implying that mARC enzymes may have a substrate spectrum going beyond the previously examined N-oxygenated compounds.
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Affiliation(s)
- Sophia Rixen
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Patrick M. Indorf
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Christian Kubitza
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Michel A. Struwe
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Cathrin Klopp
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Axel J. Scheidig
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Thomas Kunze
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Bernd Clement
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
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3
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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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4
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Salvadori E, Bruzzese PC, Giamello E, Chiesa M. Single Metal Atoms on Oxide Surfaces: Assessing the Chemical Bond through 17O Electron Paramagnetic Resonance. Acc Chem Res 2022; 55:3706-3715. [PMID: 36442497 PMCID: PMC9774661 DOI: 10.1021/acs.accounts.2c00606] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
ConspectusEven in the gas phase single atoms possess catalytic properties, which can be crucially enhanced and modulated by the chemical interaction with a solid support. This effect, known as electronic metal-support interaction, encompasses charge transfer, orbital overlap, coordination structure, etc., in other words, all the crucial features of the chemical bond. These very features are the object of this Account, with specific reference to open-shell (paramagnetic) single metal atoms or ions on oxide supports. Such atomically dispersed species are part of the emerging class of heterogeneous catalysts known as single-atom catalysts (SACs). In these materials, atomic dispersion ensures maximum atom utilization and uniform active sites, whereby the nature of the chemical interaction between the metal and the oxide surface modulates the catalytic activity of the metal active site by tuning the energy of the frontier orbitals. A comprehensive set of examples includes fourth period metal atoms and ions in zeolites on insulating (e.g., MgO) or reducible (e.g., TiO2) oxides and are among the most relevant catalysts for a wealth of key processes of industrial and environmental relevance, from the abatement of NOx to the selective oxidation of hydrocarbons and the conversion of methane to methanol.There exist several spectroscopic techniques able to inform on the geometric and electronic structure of isolated single metal ion sites, but either they yield information averaged over the bulk or they lack description of the intimate features of chemical bonding, which include covalency, ionicity, electron and spin delocalization. All of these can be recovered at once by measuring the magnetic interactions between open-shell metals and the surrounding nuclei with Electron Paramagnetic Resonance (EPR) spectroscopy. In the case of oxides, this entails the synthesis of 17O isotopically enriched materials. We have established 17O EPR as a unique source of information about the local binding environment around oxygen of magnetic atoms or ions on different oxidic supports to rationalize structure-property relationships. Here, we will describe strategies for 17O surface enrichments and approaches to monitor the state of charge and spin delocalization of atoms or ions from K to Zn dispersed on oxide surfaces characterized by different chemical properties (i.e., basicity or reducibility). Emphasis is placed on chemical insight at the atomic-scale level achieved by 17O EPR, which is a crucial step in understanding the structure-property relationships of single metal atom catalysts and in enabling efficient design of future materials for a range of end uses.
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Affiliation(s)
- Enrico Salvadori
- Department
of Chemistry and NIS Centre of Excellence, University of Turin, via Giuria 9, 10125 Torino, Italy
| | - Paolo Cleto Bruzzese
- Department
of Chemistry and NIS Centre of Excellence, University of Turin, via Giuria 9, 10125 Torino, Italy,Felix
Bloch Institute for Solid State Physics, Leipzig University, Linnéstr. 5, 04103 Leipzig, Germany
| | - Elio Giamello
- Department
of Chemistry and NIS Centre of Excellence, University of Turin, via Giuria 9, 10125 Torino, Italy
| | - Mario Chiesa
- Department
of Chemistry and NIS Centre of Excellence, University of Turin, via Giuria 9, 10125 Torino, Italy,E-mail:
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5
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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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6
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Kim Y, Kim J, Nguyen LK, Lee YM, Nam W, Kim SH. EPR spectroscopy elucidates the electronic structure of [FeV(O)(TAML)] complexes. Inorg Chem Front 2021. [DOI: 10.1039/d1qi00522g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complete hyperfine tensor of 17O of the FeV-oxo moeity was probed by ENDOR spectroscopy. The EPR spectroscopic results reported here provide a conclusive experimental basis for elucidating the electronic structure of the FeV-oxo complex.
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Affiliation(s)
- Yujeong Kim
- Western Seoul Center
- Korea Basic Science Institute (KBSI)
- Seoul 03759
- Rep. of Korea
- Department of Chemistry and Nano Science
| | - Jin Kim
- Department of Chemistry
- Sunchon National University
- Suncheon 57922
- Rep. of Korea
| | - Linh K. Nguyen
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Rep. of Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Rep. of Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Rep. of Korea
| | - Sun Hee Kim
- Western Seoul Center
- Korea Basic Science Institute (KBSI)
- Seoul 03759
- Rep. of Korea
- Department of Chemistry and Nano Science
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7
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Kirk ML, Kc K. Molybdenum and Tungsten Cofactors and the Reactions They Catalyze. Met Ions Life Sci 2020; 20:/books/9783110589757/9783110589757-015/9783110589757-015.xml. [PMID: 32851830 PMCID: PMC8176780 DOI: 10.1515/9783110589757-015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
The last 20 years have seen a dramatic increase in our mechanistic understanding of the reactions catalyzed by pyranopterin Mo and W enzymes. These enzymes possess a unique cofactor (Moco) that contains a novel ligand in bioinorganic chemistry, the pyranopterin ene-1,2-dithiolate. A synopsis of Moco biosynthesis and structure is presented, along with our current understanding of the role Moco plays in enzymatic catalysis. Oxygen atom transfer (OAT) reactivity is discussed in terms of breaking strong metal-oxo bonds and the mechanism of OAT catalyzed by enzymes of the sulfite oxidase (SO) family that possess dioxo Mo(VI) active sites. OAT reactivity is also discussed in members of the dimethyl sulfoxide (DMSO) reductase family, which possess des-oxo Mo(IV) sites. Finally, we reveal what is known about hydride transfer reactivity in xanthine oxidase (XO) family enzymes and the formate dehydrogenases. The formal hydride transfer reactivity catalyzed by xanthine oxidase family enzymes is complex and cleaves substrate C-H bonds using a mechanism that is distinct from monooxygenases. The chapter primarily highlights developments in the field that have occurred since ~2000, which have contributed to our collective structural and mechanistic understanding of the three canonical pyranopterin Mo enzymes families: XO, SO, and DMSO reductase.
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8
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Crystal structure of human mARC1 reveals its exceptional position among eukaryotic molybdenum enzymes. Proc Natl Acad Sci U S A 2018; 115:11958-11963. [PMID: 30397129 DOI: 10.1073/pnas.1808576115] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Biotransformation enzymes ensure a viable homeostasis by regulating reversible cycles of oxidative and reductive reactions. The metabolism of nitrogen-containing compounds is of high pharmaceutical and toxicological relevance because N-oxygenated metabolites derived from reactions mediated by cytochrome P450 enzymes or flavin-dependent monooxygenases are in some cases highly toxic or mutagenic. The molybdenum-dependent mitochondrial amidoxime-reducing component (mARC) was found to be an extremely efficient counterpart, which is able to reduce the full range of N-oxygenated compounds and thereby mediates detoxification reactions. However, the 3D structure of this enzyme was unknown. Here we present the high-resolution crystal structure of human mARC. We give detailed insight into the coordination of its molybdenum cofactor (Moco), the catalytic mechanism, and its ability to reduce a wide range of N-oxygenated compounds. The identification of two key residues will allow future discrimination between mARC paralogs and ensure correct annotation. Since our structural findings contradict in silico predictions that are currently made by online databases, we propose domain definitions for members of the superfamily of Moco sulfurase C-terminal (MOSC) domain-containing proteins. Furthermore, we present evidence for an evolutionary role of mARC for the emergence of the xanthine oxidase protein superfamily. We anticipate the hereby presented crystal structure to be a starting point for future descriptions of MOSC proteins, which are currently poorly structurally characterized.
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9
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Colaneri MJ, Vitali J. Probing Axial Water Bound to Copper in Tutton Salt Using Single Crystal 17O-ESEEM Spectroscopy. J Phys Chem A 2018; 122:6214-6224. [PMID: 29989412 DOI: 10.1021/acs.jpca.8b04075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Electron spin-echo envelope modulation (ESEEM) signals attributed to axial water bound to Cu2+ have been detected and analyzed in Cu(II)-doped 17O-water-enriched potassium zinc sulfate hexahydrate (Tutton salt) crystals. The magnetic field orientation dependences of low frequency modulations were measured to fit hyperfine and quadrupole coupling tensors of a 17O ( I = 5/2) nucleus. The hyperfine tensor ( A xx, A yy, A zz: 0.13, 0.23, -3.81 MHz) exhibits almost axial symmetry with the largest value directed normal to the metal equatorial plane in the host structure. Comparisons with quantum chemical calculations position this nucleus about 2.3 Å from the copper. The isotropic coupling (-1.15 MHz) is small and reflects the weak axial water interaction with a dx2-y2 unshared orbital of copper. The 17O-water quadrupole interaction parameters ( e2 qQ/ h = 6.4 MHz and η = 0.93) are close to the average of those found in a variety of solid hydrates. In addition, the coupling tensor directions correlate very closely with the O8 water geometry, with the maximum quadrupole direction 3° from the water plane normal, and its minimum coupling about 2° from the H-H direction. In almost all previous magnetic resonance 17O-water studies, the quadrupole tensor orientation was based on theoretical considerations. This work represents one of the few experimental confirmations of its principal axis frame. When Cu2+ dopes into the Tutton salt, a Jahn-Teller distortion interchanges the relative long and intermediate metal O7 and O8 bond lengths of the zinc host. Therefore, only those unit cells containing the impurity conform to the pure copper Tutton structure. This study provides further support for this model. Moreover, coupling interactions from distant H217O such as in the present case have important implications in studies of copper enzymes and proteins where substrates have been proposed to displace weakly bound water in the active site.
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Affiliation(s)
- Michael J Colaneri
- Department of Chemistry and Physics , State University of New York at Old Westbury , Old Westbury , New York 11568 , United States
| | - Jacqueline Vitali
- Department of Physics and Department of Biological, Geological and Environmental Sciences , Cleveland State University , Cleveland , Ohio 44115 , United States
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10
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Dong G, Ryde U. Effect of the protein ligand in DMSO reductase studied by computational methods. J Inorg Biochem 2017; 171:45-51. [DOI: 10.1016/j.jinorgbio.2017.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/07/2017] [Accepted: 03/19/2017] [Indexed: 11/27/2022]
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11
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Rendon J, Biaso F, Ceccaldi P, Toci R, Seduk F, Magalon A, Guigliarelli B, Grimaldi S. Elucidating the Structures of the Low- and High-pH Mo(V) Species in Respiratory Nitrate Reductase: A Combined EPR, 14,15N HYSCORE, and DFT Study. Inorg Chem 2017; 56:4423-4435. [DOI: 10.1021/acs.inorgchem.6b03129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julia Rendon
- Aix Marseille Univ, CNRS, BIP, Marseille, France
| | | | - Pierre Ceccaldi
- Aix Marseille Univ, CNRS, BIP, Marseille, France
- Aix Marseille Univ, CNRS, LCB, Marseille, France
| | - René Toci
- Aix Marseille Univ, CNRS, LCB, Marseille, France
| | - Farida Seduk
- Aix Marseille Univ, CNRS, LCB, Marseille, France
| | - Axel Magalon
- Aix Marseille Univ, CNRS, LCB, Marseille, France
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12
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Wang J, Keceli G, Cao R, Su J, Mi Z. Molybdenum-containing nitrite reductases: Spectroscopic characterization and redox mechanism. Redox Rep 2016; 22:17-25. [PMID: 27686142 DOI: 10.1080/13510002.2016.1206175] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVES This review summarizes the spectroscopic results, which will provide useful suggestions for future research. In addition, the fields that urgently need more information are also advised. BACKGROUND Nitrite-NO-cGMP has been considered as an important signaling pathway of NO in human cells. To date, all the four known human molybdenum-containing enzymes, xanthine oxidase, aldehyde oxidase, sulfite oxidase, and mitochondrial amidoxime-reducing component, have been shown to function as nitrite reductases under hypoxia by biochemical, cellular, or animal studies. Various spectroscopic techniques have been applied to investigate the structure and catalytic mechanism of these enzymes for more than 20 years. METHODS We summarize the published data on the applications of UV-vis and EPR spectroscopies, and X-ray crystallography in studying nitrite reductase activity of the four human molybdenum-containing enzymes. RESULTS UV-vis has provided useful information on the redox active centers of these enzymes. The utilization of EPR spectroscopy has been critical in determining the coordination and redox status of the Mo center during catalysis. Despite the lack of substrate-bound crystal structures of these nitrite reductases, valuable structural information has been obtained by X-ray crystallography. CONCLUSIONS To fully understand the catalytic mechanisms of these physiologically/pathologically important nitrite reductases, structural studies on substrate-redox center interaction are needed.
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Affiliation(s)
- Jun Wang
- a Department of Pharmacy, Food and Pharmaceutical Engineering College , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Gizem Keceli
- b Department of Chemistry , Johns Hopkins University , Baltimore , MD 21218 , USA
| | - Rui Cao
- b Department of Chemistry , Johns Hopkins University , Baltimore , MD 21218 , USA
| | - Jiangtao Su
- a Department of Pharmacy, Food and Pharmaceutical Engineering College , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Zhiyuan Mi
- a Department of Pharmacy, Food and Pharmaceutical Engineering College , Hubei University of Technology , Wuhan , Hubei 430068 , China
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13
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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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14
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Li J, Ryde U. Comparison of the Active-Site Design of Molybdenum Oxo-Transfer Enzymes by Quantum Mechanical Calculations. Inorg Chem 2014; 53:11913-24. [DOI: 10.1021/ic5010837] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jilai Li
- Department of Theoretical Chemistry, Chemical
Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
- State Key Laboratory of Theoretical and
Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People’s Republic of China
| | - Ulf Ryde
- Department of Theoretical Chemistry, Chemical
Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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15
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Sparacino-Watkins C, Stolz JF, Basu P. Nitrate and periplasmic nitrate reductases. Chem Soc Rev 2014; 43:676-706. [PMID: 24141308 DOI: 10.1039/c3cs60249d] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The nitrate anion is a simple, abundant and relatively stable species, yet plays a significant role in global cycling of nitrogen, global climate change, and human health. Although it has been known for quite some time that nitrate is an important species environmentally, recent studies have identified potential medical applications. In this respect the nitrate anion remains an enigmatic species that promises to offer exciting science in years to come. Many bacteria readily reduce nitrate to nitrite via nitrate reductases. Classified into three distinct types--periplasmic nitrate reductase (Nap), respiratory nitrate reductase (Nar) and assimilatory nitrate reductase (Nas), they are defined by their cellular location, operon organization and active site structure. Of these, Nap proteins are the focus of this review. Despite similarities in the catalytic and spectroscopic properties Nap from different Proteobacteria are phylogenetically distinct. This review has two major sections: in the first section, nitrate in the nitrogen cycle and human health, taxonomy of nitrate reductases, assimilatory and dissimilatory nitrate reduction, cellular locations of nitrate reductases, structural and redox chemistry are discussed. The second section focuses on the features of periplasmic nitrate reductase where the catalytic subunit of the Nap and its kinetic properties, auxiliary Nap proteins, operon structure and phylogenetic relationships are discussed.
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16
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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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Ott G, Reichmann D, Boerger C, Cascorbi I, Bittner F, Mendel RR, Kunze T, Clement B, Havemeyer A. Functional characterization of protein variants encoded by nonsynonymous single nucleotide polymorphisms in MARC1 and MARC2 in healthy Caucasians. Drug Metab Dispos 2014; 42:718-25. [PMID: 24423752 DOI: 10.1124/dmd.113.055202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Human molybdenum-containing enzyme mitochondrial amidoxime reducing component (mARC), cytochrome b5 type B, and NADH cytochrome b5 reductase form an N-reductive enzyme system that is capable of reducing N-hydroxylated compounds. Genetic variations are known, but their functional relevance is unclear. Our study aimed to investigate the incidence of nonsynonymous single nucleotide polymorphisms (SNPs) in the mARC genes in healthy Caucasian volunteers, to determine saturation of the protein variants with molybdenum cofactor (Moco), and to characterize the kinetic behavior of the protein variants by in vitro biotransformation studies. Genotype frequencies of six SNPs in the mARC genes (c.493A>G, c.560T>A, c.736T>A, and c.739G>C in MARC1; c.730G>A and c.735T>G in MARC2) were determined by pyrosequencing in a cohort of 340 healthy Caucasians. Protein variants were expressed in Escherichia coli. Saturation with Moco was determined by measurement of molybdenum by inductively coupled mass spectrometry. Steady state assays were performed with benzamidoxime. The six variants were of low frequency in this Caucasian population. Only one homozygous variant (c.493A; MARC1) was detected. All protein variants were able to bind Moco. Steady state assays showed statistically significant decreases of catalytic efficiency values for the mARC-2 wild type compared with the mARC-1 wild type (P < 0.05) and for two mARC-2 variants compared with the mARC-2 wild type (G244S, P < 0.05; C245W, P < 0.05). After simultaneous substitution of more than two amino acids in the mARC-1 protein, N-reductive activity was decreased 5-fold. One homozygous variant of MARC1 was detected in our sample. The encoded protein variant (A165T) showed no different kinetic parameters in the N-reduction of benzamidoxime.
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Affiliation(s)
- Gudrun Ott
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany (G.O., T.K., B.C., A.H.); Department of Plant Biology, Technical University of Braunschweig, Braunschweig, Germany (D.R., F.B., R.-R.M.); and Institute of Experimental and Clinical Pharmacology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany (C.B., I.C.)
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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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