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Zhang B, Boyd SD, Zhabilov D, Ullrich M, Blackburn NJ, Winkler DD. Pathogenic R 163W Variant of the Copper Chaperone for Sod1 (Ccs) Functions as an Anti-chaperone. Biochemistry 2024; 63:2051-2062. [PMID: 39099176 DOI: 10.1021/acs.biochem.4c00223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2024]
Abstract
The copper chaperone for Sod1 (Ccs) is a metallochaperone that plays a multifaceted role in the maturation of Cu,Zn superoxide dismutase (Sod1). The Ccs mutation R163W was identified in an infant with fatal neurological abnormalities. Based on a comprehensive structural and functional analysis, we developed the first data-driven model for R163W-related pathogenic phenotypes. The work here confirms previous findings that the substitution of arginine with tryptophan at this site, which is located adjacent to a conserved Zn binding site, creates an unstable Zn-deficient protein that loses its ability to efficiently activate Sod1. Intriguingly, R163W Ccs can reduce copper (i.e., Cu(II) → Cu(I)) bound in its Sod1-like domain (D2), and this novel redox event is accompanied by disulfide bond formation. The loss of Zn binding, along with the unusual ability to bind copper in D2, diverts R163W Ccs toward aggregation. The remarkably high affinity of D2 Cu(I) binding converts R163W from a Cu chaperone to a Cu scavenger that accelerates Sod1 deactivation (i.e., an Anti-chaperone). Overall, these findings present a first-of-its-kind molecular mechanism for Ccs dysfunction that leads to pathogenesis in humans.
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Affiliation(s)
- Bei Zhang
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Stefanie D Boyd
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Dannie Zhabilov
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Morgan Ullrich
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry, Oregon Health and Sciences University, Portland, Oregon 97239, United States
| | - Duane D Winkler
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
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2
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Liu JJ, He C, Liu T, Liu J, Xia SB. Two photochromic hybrid materials assembled from naphthalene diimide as photocatalysts for the degradation of carcinogenic dye basic red 9 under visible light. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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3
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Zhang L, Bill E, Kroneck PMH, Einsle O. Histidine-Gated Proton-Coupled Electron Transfer to the CuA Site of Nitrous Oxide Reductase. J Am Chem Soc 2020; 143:830-838. [DOI: 10.1021/jacs.0c10057] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Lin Zhang
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg im Breisgau, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
| | | | - Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg im Breisgau, Germany
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4
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Mirts EN, Dikanov SA, Jose A, Solomon EI, Lu Y. A Binuclear Cu A Center Designed in an All α-Helical Protein Scaffold. J Am Chem Soc 2020; 142:13779-13794. [PMID: 32662996 DOI: 10.1021/jacs.0c04226] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The primary and secondary coordination spheres of metal binding sites in metalloproteins have been investigated extensively, leading to the creation of high-performing functional metalloproteins; however, the impact of the overall structure of the protein scaffold on the unique properties of metalloproteins has rarely been studied. A primary example is the binuclear CuA center, an electron transfer cupredoxin domain of photosynthetic and respiratory complexes and, recently, a protein coregulated with particulate methane and ammonia monooxygenases. The redox potential, Cu-Cu spectroscopic features, and a valence delocalized state of CuA are difficult to reproduce in synthetic models, and every artificial protein CuA center to-date has used a modified cupredoxin. Here, we present a fully functional CuA center designed in a structurally nonhomologous protein, cytochrome c peroxidase (CcP), by only two mutations (CuACcP). We demonstrate with UV-visible absorption, resonance Raman, and magnetic circular dichroism spectroscopy that CuACcP is valence delocalized. Continuous wave and pulsed (HYSCORE) X-band EPR show it has a highly compact gz area and small Az hyperfine principal value with g and A tensors that resemble axially perturbed CuA. Stopped-flow kinetics found that CuA formation proceeds through a single T2Cu intermediate. The reduction potential of CuACcP is comparable to native CuA and can transfer electrons to a physiological redox partner. We built a structural model of the designed Cu binding site from extended X-ray absorption fine structure spectroscopy and validated it by mutation of coordinating Cys and His residues, revealing that a triad of residues (R48C, W51C, and His52) rigidly arranged on one α-helix is responsible for chelating the first Cu(II) and that His175 stabilizes the binuclear complex by rearrangement of the CcP heme-coordinating helix. This design is a demonstration that a highly conserved protein fold is not uniquely necessary to induce certain characteristic physical and chemical properties in a metal redox center.
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Affiliation(s)
- Evan N Mirts
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sergei A Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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5
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Alwan KB, Welch EF, Blackburn NJ. Catalytic M Center of Copper Monooxygenases Probed by Rational Design. Effects of Selenomethionine and Histidine Substitution on Structure and Reactivity. Biochemistry 2019; 58:4436-4446. [PMID: 31626532 DOI: 10.1021/acs.biochem.9b00823] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The M centers of the mononuclear monooxygenases peptidylglycine monooxygenase (PHM) and dopamine β-monooxygenase bind and activate dioxygen en route to substrate hydroxylation. Recently, we reported the rational design of a protein-based model in which the CusF metallochaperone was repurposed via a His to Met mutation to act as a structural and spectroscopic biomimic. The PHM M site exhibits a number of unusual attributes, including a His2Met ligand set, a fluxional Cu(I)-S(Met) bond, tight binding of exogenous ligands CO and N3-, and complete coupling of oxygen reduction to substrate hydroxylation even at extremely low turnover rates. In particular, mutation of the Met ligand to His completely eliminates the catalytic activity despite the propensity of CuI-His3 centers to bind and activate dioxygen in other metalloenzyme systems. Here, we further develop the CusF-based model to explore methionine variants in which Met is replaced by selenomethionine (SeM) and histidine. We examine the effects on coordinate structure and exogenous ligand binding via X-ray absorption spectroscopy and electron paramagnetic resonance and probe the consequences of mutations on redox chemistry via studies of the reduction by ascorbate and oxidation via molecular oxygen. The M-site model is three-coordinate in the Cu(I) state and binds CO to form a four-coordinate carbonyl. In the oxidized forms, the coordination changes to tetragonal five-coordinate with a long axial Met ligand that like the enzymes is undetectable at either the Cu or Se K edges. The EXAFS data at the Se K edge of the SeM variant provide unique information about the nature of the Cu-methionine bond that is likewise weak and fluxional. Kinetic studies document the sluggish reactivity of the Cu(I) complexes with molecular oxygen and rapid rates of reduction of the Cu(II) complexes by ascorbate, indicating a remarkable stability of the Cu(I) state in all three derivatives. The results show little difference between the Met ligand and its SeM and His congeners and suggest that the Met contributes to catalysis in ways that are more complex than simple perturbation of the redox chemistry. Overall, the results stimulate a critical re-examination of the canonical reaction mechanisms of the mononuclear copper monooxygenases.
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Affiliation(s)
- Katherine B Alwan
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Evan F Welch
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
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6
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Rao G, Alwan KB, Blackburn NJ, Britt RD. Incorporation of Ni 2+, Co 2+, and Selenocysteine into the Auxiliary Fe-S Cluster of the Radical SAM Enzyme HydG. Inorg Chem 2019; 58:12601-12608. [PMID: 31539235 DOI: 10.1021/acs.inorgchem.9b01293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The radical SAM enzyme HydG generates CO- and CN--containing Fe complexes that are involved in the bioassembly of the [FeFe] hydrogenase active cofactor, the H-cluster. HydG contains a unique 5Fe-4S cluster in which the fifth "dangler" Fe and the coordinating cysteine molecule have both been shown to be essential for its function. Here, we demonstrate that this dangler Fe can be replaced with Ni2+ or Co2+ and that the cysteine can be replaced with selenocysteine. The resulting HydG variants were characterized by electron paramagnetic resonance and X-ray absorption spectroscopy, as well as subjected to a Tyr cleavage assay. Both Ni2+ and Co2+ are shown to be exchange-coupled to the 4Fe-4S cluster, and selenocysteine substitution does not alter the electronic structure significantly. XAS data provide details of the coordination environments near the Ni, Co, and Se atoms and support a close interaction of the dangler metal with the FeS cluster via an asymmetric SeCys bridge. Finally, while we were unable to observe the formation of novel organometallic species for the Ni2+ and Co2+ variants, the selenocysteine variant retains the activity of wild type HydG in forming [Fe(CO)x(CN)y] species. Our results provide more insights into the unique auxiliary cluster in HydG and expand the scope of artificially generated Fe-S clusters with heteroatoms.
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Affiliation(s)
- Guodong Rao
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - Katherine B Alwan
- Department of Chemical Physiology and Biochemistry , Oregon Health and Science University , Portland , Oregon 97239 , United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry , Oregon Health and Science University , Portland , Oregon 97239 , United States
| | - R David Britt
- Department of Chemistry , University of California , Davis , California 95616 , United States
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7
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Canonica F, Hennecke H, Glockshuber R. Biochemical pathway for the biosynthesis of the Cu A center in bacterial cytochrome c oxidase. FEBS Lett 2019; 593:2977-2989. [PMID: 31449676 DOI: 10.1002/1873-3468.13587] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 01/25/2023]
Abstract
The di-copper center CuA is an essential metal cofactor in cytochrome oxidase (Cox) of mitochondria and many prokaryotes, mediating one-electron transfer from cytochrome c to the site for oxygen reduction. CuA is located in subunit II (CoxB) of Cox and protrudes into the periplasm of Gram-negative bacteria or the mitochondrial intermembrane space. How the two copper ions are brought together to build CoxB·CuA is the subject of this review. It had been known that the reductase TlpA and the metallochaperones ScoI and PcuC are required for CuA formation in bacteria, but the mechanism of copper transfer has emerged only recently for the Bradyrhizobium diazoefficiens system. It consists of the following steps: (a) TlpA keeps the active site cysteine pair of CoxB in its dithiol state as a prerequisite for metal insertion; (b) ScoI·Cu2+ rapidly forms a transient complex with apo-CoxB; (c) PcuC, loaded with Cu1+ and Cu2+ , dissociates this complex to CoxB·Cu2+ , and a second PcuC·Cu1+ ·Cu2+ transfers Cu1+ to CoxB·Cu2+ , yielding mature CoxB·CuA . Variants of this pathway might exist in other bacteria or mitochondria.
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Affiliation(s)
- Fabia Canonica
- Institute of Molecular Biology and Biophysics, ETH Zurich, Switzerland
| | | | - Rudi Glockshuber
- Institute of Molecular Biology and Biophysics, ETH Zurich, Switzerland
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8
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Canonica F, Klose D, Ledermann R, Sauer MM, Abicht HK, Quade N, Gossert AD, Chesnov S, Fischer HM, Jeschke G, Hennecke H, Glockshuber R. Structural basis and mechanism for metallochaperone-assisted assembly of the Cu A center in cytochrome oxidase. SCIENCE ADVANCES 2019; 5:eaaw8478. [PMID: 31392273 PMCID: PMC6669012 DOI: 10.1126/sciadv.aaw8478] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 06/26/2019] [Indexed: 06/10/2023]
Abstract
The mechanisms underlying the biogenesis of the structurally unique, binuclear Cu1.5+•Cu1.5+ redox center (CuA) on subunit II (CoxB) of cytochrome oxidases have been a long-standing mystery. Here, we reconstituted the CoxB•CuA center in vitro from apo-CoxB and the holo-forms of the copper transfer chaperones ScoI and PcuC. A previously unknown, highly stable ScoI•Cu2+•CoxB complex was shown to be rapidly formed as the first intermediate in the pathway. Moreover, our structural data revealed that PcuC has two copper-binding sites, one each for Cu1+ and Cu2+, and that only PcuC•Cu1+•Cu2+ can release CoxB•Cu2+ from the ScoI•Cu2+•CoxB complex. The CoxB•CuA center was then formed quantitatively by transfer of Cu1+ from a second equivalent of PcuC•Cu1+•Cu2+ to CoxB•Cu2+. This metalation pathway is consistent with all available in vivo data and identifies the sources of the Cu ions required for CuA center formation and the order of their delivery to CoxB.
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Affiliation(s)
- Fabia Canonica
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Daniel Klose
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | | | - Maximilian M. Sauer
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Helge K. Abicht
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Nick Quade
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Alvar D. Gossert
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Serge Chesnov
- Functional Genomics Center Zurich, University of Zurich/ETH Zurich, Zurich, Switzerland
| | | | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | - Hauke Hennecke
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Rudi Glockshuber
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
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9
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Understanding Factors that Control the Structural (Dis)Assembly of Sulphur-Bridged Bimetallic Sites. INORGANICS 2019. [DOI: 10.3390/inorganics7040042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Bimetallic structures of the general type [M2(µ-S)2] are omnipresent in nature, for biological function [M2(µ-S)2] sites interconvert between electronically distinct, but isostructural, forms. Different from structure-function relationships, the current understanding of the mechanism of formation and persistence of [M2(µ-S)2] sites is poorly developed. This work reports on bimetallic model compounds of nickel that interconvert between functional structures [Ni2(µ-S)2]+/2+ and isomeric congeners [2{κ-S–Ni}]2+/+, S = Aryl-S−, in which the nickel ions are geometrically independent. Interconversion of the two sets of structures was studied quantitatively by UV–VIS absorption spectroscopy and cyclic voltammetry. Assembly of the [Ni2(µ-S)2]+ core from [2{κ-S–Ni}]+ is thermodynamically and kinetically highly preferred over the disassembly of [Ni2(µ-S)2]2+ into [2{κ-S–Ni}]2+. Labile Ni-η2/3-bonding to aromatic π-systems of the primary thiophenol ligand is critical for modeling (dis)assembly processes. A phosphine coligand mimics the role of anionic donors present in natural sites that saturate metal coordination. Three parameters have been identified as critical for structure formation and persistence. These are, first, the stereoelectronic properties of the metals ions, second, the steric demand of the coligand, and, third, the properties of the dative bond between nickel and coligand. The energies of transition states connecting functional and precursor forms have been found to depend on these parameters.
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10
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Ross MO, Fisher OS, Morgada MN, Krzyaniak MD, Wasielewski MR, Vila AJ, Hoffman BM, Rosenzweig AC. Formation and Electronic Structure of an Atypical Cu A Site. J Am Chem Soc 2019; 141:4678-4686. [PMID: 30807125 PMCID: PMC6953997 DOI: 10.1021/jacs.8b13610] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PmoD, a recently discovered protein from methane-oxidizing bacteria, forms a homodimer with a dicopper CuA center at the dimer interface. Although the optical and electron paramagnetic resonance (EPR) spectroscopic signatures of the PmoD CuA bear similarities to those of canonical CuA sites, there are also some puzzling differences. Here we have characterized the rapid formation (seconds) and slow decay (hours) of this homodimeric CuA site to two mononuclear Cu2+ sites, as well as its electronic and geometric structure, using stopped-flow optical and advanced paramagnetic resonance spectroscopies. PmoD CuA formation occurs rapidly and involves a short-lived intermediate with a λmax of 360 nm. Unlike other CuA sites, the PmoD CuA is unstable, decaying to two type 2 Cu2+ centers. Surprisingly, NMR data indicate that the PmoD CuA has a pure σu* ground state rather than the typical equilibrium between σu* and πu of all other CuA proteins. EPR, ENDOR, ESEEM, and HYSCORE data indicate the presence of two histidine and two cysteine ligands coordinating the CuA core in a highly symmetrical fashion. This report significantly expands the diversity and understanding of known CuA sites.
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Affiliation(s)
- Matthew O. Ross
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Oriana S. Fisher
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Marcos N. Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Ocampo y Esmeralda, S2002LRK Rosario, Argentina
- Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina
| | - Matthew D. Krzyaniak
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Michael R. Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Ocampo y Esmeralda, S2002LRK Rosario, Argentina
| | - Brian M. Hoffman
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Amy C. Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
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11
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Priyanga S, Khamrang T, Velusamy M, Karthi S, Ashokkumar B, Mayilmurugan R. Coordination geometry-induced optical imaging of l-cysteine in cancer cells using imidazopyridine-based copper(ii) complexes. Dalton Trans 2019; 48:1489-1503. [PMID: 30632585 DOI: 10.1039/c8dt04634d] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Overexpression of cysteine cathepsins proteases has been documented in a wide variety of cancers, and enhances the l-cysteine concentration in tumor cells. We report the synthesis and characterization of copper(ii) complexes [Cu(L1)2(H2O)](SO3CF3)2, 1, L1 = 3-phenyl-1-(pyridin-2-yl)imidazo[1,5-a]pyridine, [Cu(L2)2(SO3CF3)]SO3CF3, 2, L2 = 3-(4-methoxyphenyl)-1-pyridin-2-yl-imidazo[1,5-a]pyridine, [Cu(L3)2(H2O)](SO3CF3)2, 3, L3 = 3-(3,4-dimethoxy-phenyl)-1-pyridin-2-yl-imidazo[1,5-a]pyridine and [Cu(L4)2(H2O)](SO3CF3)2, 4, L4 = dimethyl-[4-(1-pyridin-2-yl-imidazo[1,5-a]pyridin-3-yl)phenyl]amine as 'turn-on' optical imaging probes for l-cysteine in cancer cells. The molecular structure of complexes adopted distorted trigonal pyramidal geometry (τ, 0.68-0.87). Cu-Npy bonds (1.964-1.989 Å) were shorter than Cu-Nimi bonds (2.024-2.074 Å) for all complexes. Geometrical distortion was strongly revealed in EPR spectra, showing g‖ (2.26-2.28) and A‖ values (139-163 × 10-4 cm-1) at 70 K. The d-d transitions appeared around 680-741 and 882-932 nm in HEPES, which supported the existence of five-coordinate geometry in solution. The Cu(ii)/Cu(i) redox potential of 1 (0.221 V vs. NHE) was almost identical to that of 2 and 3 but lower than that of 4 (0.525 V vs. NHE) in HEPES buffer. The complexes were almost non-emissive in nature, but became emissive by the interaction of l-cysteine in 100% HEPES at pH 7.34 via reduction of Cu(ii) to Cu(i). Among the probes, probe 2 showed selective and efficient turn-on fluorescence behavior towards l-cysteine over natural amino acids with a limit of detection of 9.9 × 10-8 M and binding constant of 2.3 × 105 M-1. The selectivity of 2 may have originated from a nearly perfect trigonal plane adopted around a copper(ii) center (∼120.70°), which required minimum structural change during the reduction of Cu(ii) to Cu(i) while imaging Cys. The other complexes, with their distorted trigonal planes, required more reorganizational energy, which resulted in poor selectivity. Probe 2 was employed for optical imaging of l-cysteine in HeLa cells and macrophages. It exhibited brighter fluorescent images by visualizing Cys at pH 7.34 and 37 °C. It showed relatively less toxicity for these cell lines as ascertained by the MTT assay.
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Affiliation(s)
- Selvarasu Priyanga
- Bioinorganic Chemistry Laboratory/Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, 625021, India.
| | - Themmila Khamrang
- Department of Chemistry, North-Eastern Hill University, Shillong, 793022, India
| | - Marappan Velusamy
- Department of Chemistry, North-Eastern Hill University, Shillong, 793022, India
| | - Sellamuthu Karthi
- School of Biotechnology, Madurai Kamaraj University, Madurai, 625 021, India
| | | | - Ramasamy Mayilmurugan
- Bioinorganic Chemistry Laboratory/Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, 625021, India.
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12
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Trapping intermediates in metal transfer reactions of the CusCBAF export pump of Escherichia coli. Commun Biol 2018; 1:192. [PMID: 30456313 PMCID: PMC6235853 DOI: 10.1038/s42003-018-0181-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/13/2018] [Indexed: 12/20/2022] Open
Abstract
Escherichia coli CusCBAF represents an important class of bacterial efflux pump exhibiting selectivity towards Cu(I) and Ag(I). The complex is comprised of three proteins: the CusA transmembrane pump, the CusB soluble adaptor protein, and the CusC outer-membrane pore, and additionally requires the periplasmic metallochaperone CusF. Here we used spectroscopic and kinetic tools to probe the mechanism of copper transfer between CusF and CusB using selenomethionine labeling of the metal-binding Met residues coupled to RFQ-XAS at the Se and Cu edges. The results indicate fast formation of a protein-protein complex followed by slower intra-complex metal transfer. An intermediate coordinated by ligands from each protein forms in 100 ms. Stopped-flow fluorescence of the capping CusF-W44 tryptophan that is quenched by metal transfer also supports this mechanism. The rate constants validate a process in which shared-ligand complex formation assists protein association, providing a driving force that raises the rate into the diffusion-limited regime.
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13
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Maiti BK, Maia LB, Moro AJ, Lima JC, Cordas CM, Moura I, Moura JJG. Unusual Reduction Mechanism of Copper in Cysteine-Rich Environment. Inorg Chem 2018; 57:8078-8088. [PMID: 29956539 DOI: 10.1021/acs.inorgchem.8b00121] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Copper-cysteine interactions play an important role in Biology and herein we used the copper-substituted rubredoxin (Cu-Rd) from Desulfovibrio gigas to gain further insights into the copper-cysteine redox chemistry. EPR spectroscopy results are consistent with Cu-Rd harboring a CuII center in a sulfur-rich coordination, in a distorted tetrahedral structure ( g∥,⊥ = 2.183 and 2.032 and A∥,⊥ = 76.4 × 10-4 and 12 × 10-4 cm-1). In Cu-Rd, two oxidation states at Cu-center (CuII and CuI) are associated with Cys oxidation-reduction, alternating in the redox cycle, as pointed by electrochemical studies that suggest internal geometry rearrangements associated with the electron transfer processes. The midpoint potential of [CuI(S-Cys)2(Cys-S-S-Cys)]/[CuII(S-Cys)4] redox couple was found to be -0.15 V vs NHE showing a large separation of cathodic and anodic peaks potential (Δ Ep = 0.575 V). Interestingly, sulfur-rich CuII-Rd is highly stable under argon in dark conditions, which is thermodynamically unfavorable to Cu-thiol autoreduction. The reduction of copper and concomitant oxidation of Cys can both undergo two possible pathways: oxidative as well as photochemical. Under O2, CuII plays the role of the electron carrier from one Cys to O2 followed by internal geometry rearrangement at the Cu site, which facilitates reduction at Cu-center to yield CuI(S-Cys)2(Cys-S-S-Cys). Photoinduced (irradiated at λex = 280 nm) reduction of the CuII center is observed by UV-visible photolysis (above 300 nm all bands disappeared) and tryptophan fluorescence (∼335 nm peak enhanced) experiments. In both pathways, geometry reorganization plays an important role in copper reduction yielding an energetically compatible donor-acceptor system. This model system provides unusual stability and redox chemistry rather than the universal Cu-thiol auto redox chemistry in cysteine-rich copper complexes.
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Affiliation(s)
- Biplab K Maiti
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
| | - Luisa B Maia
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
| | - Artur J Moro
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
| | - João C Lima
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
| | - Cristina M Cordas
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
| | - Isabel Moura
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
| | - José J G Moura
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia , Universidade Nova de Lisboa , 2829-516 Caparica , Portugal
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14
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Koch F, Berkefeld A, Speiser B, Schubert H. Mechanistic Aspects of Redox-Induced Assembly and Disassembly of S-Bridged [2M-2S] Structures. Chemistry 2017; 23:16681-16690. [PMID: 28976037 DOI: 10.1002/chem.201704599] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Indexed: 11/06/2022]
Abstract
Sulfur-bridged binuclear structures [2M-2S] play a pivotal role in a variety of chemical processes such as bond breaking and formation and electron transfer. In general, structural persistence is deemed essential to the respective function but owing to the lack of a suitable molecular model system, the current understanding of the factors that control the thermodynamic and kinetic stability of [2M-2S] cores clearly is limited. This work reports a series of binuclear complexes of nickel derived from a 1,4-terphenyldithiophenol ligand platform that is ideally suited for mechanistic work to overcome this limitation. Redox-induced assembly and disassembly of S-bridged [2M-2S] fragments have been investigated at the molecular level. As part of an extended square scheme, metastable binuclear structures that are significant mechanistically have been identified, characterized, and their reactivity studied quantitatively. Electronic properties that are inherent to [2M-2S] structures and determine thermodynamic and kinetic stability are differentiated from steric effects imposed by co-ligands.
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Affiliation(s)
- Felix Koch
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Germany
| | - Andreas Berkefeld
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Germany
| | - Bernd Speiser
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Germany
| | - Hartmut Schubert
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Germany
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15
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Kline CD, Gambill BF, Mayfield M, Lutsenko S, Blackburn NJ. pH-regulated metal-ligand switching in the HM loop of ATP7A: a new paradigm for metal transfer chemistry. Metallomics 2017; 8:729-33. [PMID: 27242196 DOI: 10.1039/c6mt00062b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cuproproteins such as PHM and DBM mature in late endosomal vesicles of the mammalian secretory pathway where changes in vesicle pH are employed for sorting and post-translational processing. Colocation with the P1B-type ATPase ATP7A suggests that the latter is the source of copper and supports a mechanism where selectivity in metal transfer is achieved by spatial colocation of partner proteins in their specific organelles or vesicles. In previous work we have suggested that a lumenal loop sequence located between trans-membrane helices TM1 and TM2 of the ATPase, and containing five histidines and four methionines, acts as an organelle-specific chaperone for metallation of the cuproproteins. The hypothesis posits that the pH of the vesicle regulates copper ligation and loop conformation via a mechanism which involves His to Met ligand switching induced by histidine protonation. Here we report the effect of pH on the HM loop copper coordination using X-ray absorption spectroscopy (XAS), and show via selenium substitution of the Met residues that the HM loop undergoes similar conformational switching to that found earlier for its partner PHM. We hypothesize that in the absence of specific chaperones, HM motifs provide a template for building a flexible, pH-sensitive transfer site whose structure and function can be regulated to accommodate the different active site structural elements and pH environments of its partner proteins.
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Affiliation(s)
- Chelsey D Kline
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
| | - Benjamin F Gambill
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
| | - Mary Mayfield
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
| | - Svetlana Lutsenko
- Department of Physiology, The Johns Hopkins University, Baltimore, Maryland 21205, USA
| | - Ninian J Blackburn
- Institute of Environmental Health, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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16
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Chen H, Su B, Zhang T, Huang A, Liu H, Yu Y, Wang J. Engineering the metal-binding loop at a type 1 copper center by circular permutation. RSC Adv 2017. [DOI: 10.1039/c7ra11512a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Circular permutation of the cupredoxin azurin creates a break on the metal binding loop, highlighting the loop's flexibility.
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Affiliation(s)
- Honghui Chen
- College of Biotechnology
- Tianjin University of Science and Technology
- Tianjin
- China
- Tianjin Institute of Industrial Biotechnology
| | - Binbin Su
- College of Biotechnology
- Tianjin University of Science and Technology
- Tianjin
- China
- Tianjin Institute of Industrial Biotechnology
| | - Tongtong Zhang
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Aiping Huang
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Haiping Liu
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Yang Yu
- Tianjin Institute of Industrial Biotechnology
- Chinese Academy of Sciences
- Tianjin
- China
| | - Jiangyun Wang
- Laboratory of RNA Biology
- Institute of Biophysics
- Chinese Academy of Sciences
- Beijing
- China
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17
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Mei X, Alvarez J, Bon Ramos A, Samanta U, Iwata-Reuyl D, Swairjo MA. Crystal structure of the archaeosine synthase QueF-like-Insights into amidino transfer and tRNA recognition by the tunnel fold. Proteins 2016; 85:103-116. [PMID: 27802572 DOI: 10.1002/prot.25202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 10/20/2016] [Accepted: 10/23/2016] [Indexed: 11/10/2022]
Abstract
The tunneling-fold (T-fold) structural superfamily has emerged as a versatile protein scaffold of diverse catalytic activities. This is especially evident in the pathways to the 7-deazaguanosine modified nucleosides of tRNA queuosine and archaeosine. Four members of the T-fold superfamily have been confirmed in these pathways and here we report the crystal structure of a fifth enzyme; the recently discovered amidinotransferase QueF-Like (QueF-L), responsible for the final step in the biosynthesis of archaeosine in the D-loop of tRNA in a subset of Crenarchaeota. QueF-L catalyzes the conversion of the nitrile group of the 7-cyano-7-deazaguanine (preQ0 ) base of preQ0 -modified tRNA to a formamidino group. The structure, determined in the presence of preQ0 , reveals a symmetric T-fold homodecamer of two head-to-head facing pentameric subunits, with 10 active sites at the inter-monomer interfaces. Bound preQ0 forms a stable covalent thioimide bond with a conserved active site cysteine similar to the intermediate previously observed in the nitrile reductase QueF. Despite distinct catalytic functions, phylogenetic distributions, and only 19% sequence identity, the two enzymes share a common preQ0 binding pocket, and likely a common mechanism of thioimide formation. However, due to tight twisting of its decamer, QueF-L lacks the NADPH binding site present in QueF. A large positively charged molecular surface and a docking model suggest simultaneous binding of multiple tRNA molecules and structure-specific recognition of the D-loop by a surface groove. The structure sheds light on the mechanism of nitrile amidation, and the evolution of diverse chemistries in a common fold. Proteins 2016; 85:103-116. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Xianghan Mei
- Department of Chemistry and Biochemistry, San Diego State University- 5500 Campanile Drive, San Diego, California, 92182
| | - Jonathan Alvarez
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, 91766-1854
| | - Adriana Bon Ramos
- Department of Chemistry, Portland State University, Portland, Oregon, 97207
| | - Uttamkumar Samanta
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, 91766-1854
| | - Dirk Iwata-Reuyl
- Department of Chemistry, Portland State University, Portland, Oregon, 97207
| | - Manal A Swairjo
- Department of Chemistry and Biochemistry, San Diego State University- 5500 Campanile Drive, San Diego, California, 92182
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18
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Dutta Gupta D, Usharani D, Mazumdar S. Mono-nuclear copper complexes mimicking the intermediates for the binuclear copper center of the subunit II of cytochrome oxidase: a peptide based approach. Dalton Trans 2016; 45:17624-17632. [PMID: 27747364 DOI: 10.1039/c6dt02977a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three stable copper complexes of peptides derived from the copper ion binding loop of the subunit II of cytochrome c oxidase have been prepared and characterized by various spectroscopic techniques. These stable copper complexes of peptides were found to exhibit cysteine, histidine and/or methionine ligation, which has predominant σ-contribution in the Cys-Cu charge transfer. The copper(ii) peptide complexes showed type-2 EPR spectra, which is uncommon in copper-cysteinate complexes. UV-visible spectra, Raman and EPR results support a tetragonal structure of the coordination geometry around the copper ion. The copper complex of the 9-amino acid peptide suggested the formation of a 'red' copper center while the copper complexes of the 12- and 11-amino acid peptides showed the formation of a 'green' copper center. The results provide insights on the first stable models of the copper complexes formed in the peptide scaffold that mimic the mono-nuclear copper bound protein intermediates proposed during the formation of the binuclear Cu2S2 core of the enzyme. These three copper complexes of peptides derived from the metal ion binding loop of the CuA center of the subunit II of cytochrome c oxidase showed novel spectroscopic properties which have not so far been reported in any stable small complex.
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Affiliation(s)
- Dwaipayan Dutta Gupta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
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19
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Wahba HM, Lecoq L, Stevenson M, Mansour A, Cappadocia L, Lafrance-Vanasse J, Wilkinson KJ, Sygusch J, Wilcox DE, Omichinski JG. Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg-Carbon Bond Cleavage and Metal Binding Specificity. Biochemistry 2016; 55:1070-81. [PMID: 26820485 DOI: 10.1021/acs.biochem.5b01298] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg-carbon bonds. Two cysteines (C96 and C159; Escherichia coli MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an E. coli MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (Bacillus megaterium MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu(II) from UV-vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the B. megaterium MerB2 protein does not copurify with copper, but the structure of the B. megaterium MerB2-Hg complex is highly similar to the structure of the MerB D99S-Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL.
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Affiliation(s)
- Haytham M Wahba
- Faculty of Pharmacy, Beni-suef University , Beni-suef, Egypt
| | | | - Michael Stevenson
- Department of Chemistry, Dartmouth College , Hanover, New Hampshire 03755, United States
| | | | | | | | | | | | - Dean E Wilcox
- Department of Chemistry, Dartmouth College , Hanover, New Hampshire 03755, United States
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20
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Chakraborty S, Polen MJ, Chacón KN, Wilson TD, Yu Y, Reed J, Nilges MJ, Blackburn NJ, Lu Y. Binuclear Cu(A) Formation in Biosynthetic Models of Cu(A) in Azurin Proceeds via a Novel Cu(Cys)2His Mononuclear Copper Intermediate. Biochemistry 2016; 54:6071-81. [PMID: 26352296 DOI: 10.1021/acs.biochem.5b00659] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cu(A) is a binuclear electron transfer (ET) center found in cytochrome c oxidases (CcOs), nitrous oxide reductases (N₂ORs), and nitric oxide reductase (NOR). In these proteins, the Cu(A) centers facilitate efficient ET (kET > 10⁴s⁻¹) under low thermodynamic driving forces (10-90 mV). While the structure and functional properties of Cu(A) are well understood, a detailed mechanism of the incorporation of copper into the protein and the identity of the intermediates formed during the Cu(A) maturation process are still lacking. Previous studies of the Cu(A) assembly mechanism in vitro using a biosynthetic model Cu(A) center in azurin (Cu(A)Az) identified a novel intermediate X (Ix) during reconstitution of the binuclear site. However, because of the instability of Ix and the coexistence of other Cu centers, such as Cu(A)' and type 1 copper centers, the identity of this intermediate could not be established. Here, we report the mechanism of Cu(A) assembly using variants of Glu114XCuAAz (X = Gly, Ala, Leu, or Gln), the backbone carbonyl of which acts as a ligand to the Cu(A) site, with a major focus on characterization of the novel intermediate Ix. We show that Cu(A) assembly in these variants proceeds through several types of Cu centers, such as mononuclear red type 2 Cu, the novel intermediate Ix, and blue type 1 Cu. Our results show that the backbone flexibility of the Glu114 residue is an important factor in determining the rates of T2Cu → Ix formation, suggesting that Cu(A) formation is facilitated by swinging of the ligand loop, which internalizes the T2Cu capture complex to the protein interior. The kinetic data further suggest that the nature of the Glu114 side chain influences the time scales on which these intermediates are formed, the wavelengths of the absorption peaks, and how cleanly one intermediate is converted to another. Through careful understanding of these mechanisms and optimization of the conditions, we have obtained Ix in ∼80-85% population in these variants, which allowed us to employ ultraviolet-visible, electron paramagnetic resonance, and extended X-ray absorption fine structure spectroscopic techniques to identify the Ix as a mononuclear Cu(Cys)(2)(His) complex. Because some of the intermediates have been proposed to be involved in the assembly of native Cu(A), these results shed light on the structural features of the important intermediates and mechanism of Cu(A) formation.
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Affiliation(s)
- Saumen Chakraborty
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Michael J Polen
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Kelly N Chacón
- Institute of Environmental Health, Oregon Health & Sciences University , Portland, Oregon 97239, United States
| | - Tiffany D Wilson
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Julian Reed
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Mark J Nilges
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Ninian J Blackburn
- Institute of Environmental Health, Oregon Health & Sciences University , Portland, Oregon 97239, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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21
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Ji W, Qu J, Jing S, Zhu D, Huang W. Copper(i) halide clusters based upon ferrocenylchalcogenoether ligands: donors, halides and semi-rigidity effects on the geometry and catalytic activity. Dalton Trans 2016; 45:1016-24. [DOI: 10.1039/c5dt03993b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Six copper(i) clusters based on ferrocenylchalcogenoethers with different nuclearities and geometries were prepared. Telluroether-based cluster 2 effectively catalyzes the C–N cross-coupling reaction.
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Affiliation(s)
- Wei Ji
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211800
- China
- School of Chemical Engineering
| | - Jian Qu
- Institute of Advanced Materials
- Nanjing Tech University
- Nanjing 210009
- China
| | - Su Jing
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211800
- China
| | - Dunru Zhu
- School of Chemical Engineering
- Nanjing Tech University
- Nanjing 210009
- China
| | - Wei Huang
- Institute of Advanced Materials
- Nanjing Tech University
- Nanjing 210009
- China
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22
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Tracking metal ions through a Cu/Ag efflux pump assigns the functional roles of the periplasmic proteins. Proc Natl Acad Sci U S A 2014; 111:15373-8. [PMID: 25313055 DOI: 10.1073/pnas.1411475111] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Copper is an essential nutrient for all aerobic organisms but is toxic in excess. At the host-pathogen interface, macrophages respond to bacterial infection by copper-dependent killing mechanisms, whereas the invading bacteria are thought to counter with an up-regulation of copper transporters and efflux pumps. The tripartite efflux pump CusCBA and its metallochaperone CusF are vital to the detoxification of copper and silver ions in the periplasm of Escherichia coli. However, the mechanism of efflux by this complex, which requires the activation of the inner membrane pump CusA, is poorly understood. Here, we use selenomethionine (SeM) active site labels in a series of biological X-ray absorption studies at the selenium, copper, and silver edges to establish a "switch" role for the membrane fusion protein CusB. We determine that metal-bound CusB is required for activation of cuprous ion transfer from CusF directly to a site in the CusA antiporter, showing for the first time (to our knowledge) the in vitro activation of the Cus efflux pump. This metal-binding site of CusA is unlike that observed in the crystal structures of the CusA protein and is composed of one oxygen and two sulfur ligands. Our results suggest that metal transfer occurs between CusF and apo-CusB, and that, when metal-loaded, CusB plays a role in the regulation of metal ion transfer from CusF to CusA in the periplasm.
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23
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Abicht HK, Schärer MA, Quade N, Ledermann R, Mohorko E, Capitani G, Hennecke H, Glockshuber R. How periplasmic thioredoxin TlpA reduces bacterial copper chaperone ScoI and cytochrome oxidase subunit II (CoxB) prior to metallation. J Biol Chem 2014; 289:32431-44. [PMID: 25274631 DOI: 10.1074/jbc.m114.607127] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two critical cysteine residues in the copper-A site (Cu(A)) on subunit II (CoxB) of bacterial cytochrome c oxidase lie on the periplasmic side of the cytoplasmic membrane. As the periplasm is an oxidizing environment as compared with the reducing cytoplasm, the prediction was that a disulfide bond formed between these cysteines must be eliminated by reduction prior to copper insertion. We show here that a periplasmic thioredoxin (TlpA) acts as a specific reductant not only for the Cu(2+) transfer chaperone ScoI but also for CoxB. The dual role of TlpA was documented best with high-resolution crystal structures of the kinetically trapped TlpA-ScoI and TlpA-CoxB mixed disulfide intermediates. They uncovered surprisingly disparate contact sites on TlpA for each of the two protein substrates. The equilibrium of CoxB reduction by TlpA revealed a thermodynamically favorable reaction, with a less negative redox potential of CoxB (E'0 = -231 mV) as compared with that of TlpA (E'0 = -256 mV). The reduction of CoxB by TlpA via disulfide exchange proved to be very fast, with a rate constant of 8.4 × 10(4) M(-1) s(-1) that is similar to that found previously for ScoI reduction. Hence, TlpA is a physiologically relevant reductase for both ScoI and CoxB. Although the requirement of ScoI for assembly of the Cu(A)-CoxB complex may be bypassed in vivo by high environmental Cu(2+) concentrations, TlpA is essential in this process because only reduced CoxB can bind copper ions.
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Affiliation(s)
- Helge K Abicht
- From the Institute of Molecular Biology and Biophysics and Institute of Microbiology, ETH Zürich, CH-8093 Zürich and
| | - Martin A Schärer
- From the Institute of Molecular Biology and Biophysics and the Laboratory of Biomolecular Research, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - Nick Quade
- From the Institute of Molecular Biology and Biophysics and
| | | | | | - Guido Capitani
- the Laboratory of Biomolecular Research, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
| | - Hauke Hennecke
- Institute of Microbiology, ETH Zürich, CH-8093 Zürich and
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24
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Yu F, Cangelosi VM, Zastrow ML, Tegoni M, Plegaria JS, Tebo AG, Mocny CS, Ruckthong L, Qayyum H, Pecoraro VL. Protein design: toward functional metalloenzymes. Chem Rev 2014; 114:3495-578. [PMID: 24661096 PMCID: PMC4300145 DOI: 10.1021/cr400458x] [Citation(s) in RCA: 340] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Fangting Yu
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | | | | | | | - Alison G. Tebo
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Leela Ruckthong
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hira Qayyum
- University of Michigan, Ann Arbor, Michigan 48109, United States
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25
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Abriata LA, Vila AJ, Dal Peraro M. Molecular dynamics simulations of apocupredoxins: insights into the formation and stabilization of copper sites under entatic control. J Biol Inorg Chem 2014; 19:565-75. [PMID: 24477946 DOI: 10.1007/s00775-014-1108-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/30/2013] [Indexed: 10/25/2022]
Abstract
Cupredoxins perform copper-mediated long-range electron transfer (ET) in biological systems. Their copper-binding sites have evolved to force copper ions into ET-competent systems with decreased reorganization energy, increased reduction potential, and a distinct electronic structure compared with those of non-ET-competent copper complexes. The entatic or rack-induced state hypothesis explains these special properties in terms of the strain that the protein matrix exerts on the metal ions. This idea is supported by X-ray structures of apocupredoxins displaying "closed" arrangements of the copper ligands like those observed in the holoproteins; however, it implies completely buried copper-binding atoms, conflicting with the notion that they must be exposed for copper loading. On the other hand, a recent work based on NMR showed that the copper-binding regions of apocupredoxins are flexible in solution. We have explored five cupredoxins in their "closed" apo forms through molecular dynamics simulations. We observed that prearranged ligand conformations are not stable as the X-ray data suggest, although they do form part of the dynamic landscape of the apoproteins. This translates into variable flexibility of the copper-binding regions within a rigid fold, accompanied by fluctuations of the hydrogen bonds around the copper ligands. Major conformations with solvent-exposed copper-binding atoms could allow initial binding of the copper ions. An eventual subsequent incursion to the closed state would result in binding of the remaining ligands, trapping the closed conformation thanks to the additional binding energy and the fastening of noncovalent interactions that make up the rack.
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Affiliation(s)
- Luciano A Abriata
- Laboratory of Biomolecular Modeling, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland,
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26
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Axial interactions in the mixed-valent CuA active site and role of the axial methionine in electron transfer. Proc Natl Acad Sci U S A 2013; 110:14658-63. [PMID: 23964128 DOI: 10.1073/pnas.1314242110] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Within Cu-containing electron transfer active sites, the role of the axial ligand in type 1 sites is well defined, yet its role in the binuclear mixed-valent CuA sites is less clear. Recently, the mutation of the axial Met to Leu in a CuA site engineered into azurin (CuA Az) was found to have a limited effect on E(0) relative to this mutation in blue copper (BC). Detailed low-temperature absorption and magnetic circular dichroism, resonance Raman, and electron paramagnetic resonance studies on CuA Az (WT) and its M123X (X = Q, L, H) axial ligand variants indicated stronger axial ligation in M123L/H. Spectroscopically validated density functional theory calculations show that the smaller ΔE(0) is attributed to H2O coordination to the Cu center in the M123L mutant in CuA but not in the equivalent BC variant. The comparable stabilization energy of the oxidized over the reduced state in CuA and BC (CuA ∼ 180 mV; BC ∼ 250 mV) indicates that the S(Met) influences E(0) similarly in both. Electron delocalization over two Cu centers in CuA was found to minimize the Jahn-Teller distortion induced by the axial Met ligand and lower the inner-sphere reorganization energy. The Cu-S(Met) bond in oxidized CuA is weak (5.2 kcal/mol) but energetically similar to that of BC, which demonstrates that the protein matrix also serves an entatic role in keeping the Met bound to the active site to tune down E(0) while maintaining a low reorganization energy required for rapid electron transfer under physiological conditions.
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Ghosh MK, Basak P, Mazumdar S. Mechanism of copper incorporation in subunit II of cytochrome C oxidase from Thermus thermophilus: identification of intermediate species. Biochemistry 2013; 52:4620-35. [PMID: 23745508 DOI: 10.1021/bi400101g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Detailed spectroscopic and kinetic studies of incorporation of copper ion in the wild type (WT) and the D111AA (AA = K, N, or E) mutants of the metal ion binding site of the soluble fragment of subunit II of cytochrome c oxidase from Thermus thermophilus (TtCuA) showed the formation of at least two distinct intermediates. The global analyses of the multiwavelength kinetic results suggested a four-step reaction scheme involving two distinct intermediates in the pathway of incorporation of copper ions into the apoprotein forming the purple dinuclear CuA. An early intermediate similar to the red copper binding proteins was detected in the WT as well as in all the mutants. The second intermediate was a green copper species in the case of WT TtCuA. Mutation of Asp111, however, formed a second intermediate that is distinctly different from that formed in the case of the WT protein, suggesting that mutants follow pathways of copper ion incorporation different from that in the WT protein. The electrostatic interaction between Asp111 and the coordinating His114 possibly plays a subtle role in the mechanism of incorporation of metal ion into the protein. The overall Kd for WT TtCuA was found to be ~8 nM, which changed with mutation of the Asp111 residue. The activation and thermodynamic parameters were also determined from the temperature- and pH-dependent multiwavelength kinetics, and the results are discussed to unravel the role of Asp111 in the mechanism of formation of the dinuclear CuA center in cytochrome c oxidase.
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Affiliation(s)
- Manas Kumar Ghosh
- Department of Chemical Sciences, Tata Institute of Fundamental Research , Colaba, Mumbai 400005, India
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Sprödefeld A, Kiel A, Herten DP, Krämer R. Monitoring Cu2+-Binding to a DNA-Clip-phen Conjugate and Metal-centered Redox Processes by a Fluorescent Reporter Group. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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