51
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Walker TL, Mula S, Malasi W, Engle JT, Ziegler CJ, van der Est A, Modarelli J, Taschner MJ. Blue copper protein analogue: synthesis and characterization of copper complexes of the N2S2 macrocycle 1,8-dithia-4,11-diazacyclotetradecane. Dalton Trans 2015; 44:20200-6. [PMID: 26536355 DOI: 10.1039/c5dt03389f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To improve understanding of copper at the active site of Type 1 copper proteins, Cu(I) and Cu(II) complexes of 1,8-dithia-4,11-diazacyclotetradecane, shown in , have been successfully isolated and structurally characterized by X-ray crystallography. In these compounds, both Cu(I) and Cu(II) are centered in the plane of the macrocycle containing two sulphur and two nitrogen heteroatoms comprising the distorted tetrahedral/square planar coordination geometry. The UV/VIS spectra, electrochemistry and EPR properties have been obtained for the Cu(II) complex 2. Three absorption bands at 295 nm, 354 nm, and 545 nm are observed in aqueous solution at a pH of 5. These bands have been assigned to the N → Cu(II) and S → Cu(II) charge transfer bands and the d-d transitions respectively. The Cu(I/II) redox midpoint potential of complex 2 in CH3CN is +403 mV versus NHE.
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Affiliation(s)
- Tia L Walker
- Department of Chemistry, Indiana University Northwest, Gary, IN 46408, USA.
| | - Sam Mula
- Department of Chemistry, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Wilhelm Malasi
- Department of Chemistry, The University of Akron, Akron, OH 44335, USA
| | - James T Engle
- Department of Chemistry, The University of Akron, Akron, OH 44335, USA
| | | | - Art van der Est
- Department of Chemistry, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Jody Modarelli
- Department of Chemistry, Hiram College, Hiram, OH 44234, USA
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52
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Błaziak K, Panek JJ, Jezierska A. Molecular reorganization of selected quinoline derivatives in the ground and excited states—Investigations via static DFT. J Chem Phys 2015. [PMID: 26203021 DOI: 10.1063/1.4926649] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Quinoline derivatives are interesting objects to study internal reorganizations due to the observed excited-state-induced intramolecular proton transfer (ESIPT). Here, we report on computations for selected 12 quinoline derivatives possessing three kinds of intramolecular hydrogen bonds. Density functional theory was employed for the current investigations. The metric and electronic structure simulations were performed for the ground state and first excited singlet and triplet states. The computed potential energy profiles do not show a spontaneous proton transfer in the ground state, whereas excited states exhibit this phenomenon. Atoms in Molecules (AIM) theory was applied to study the nature of hydrogen bonding, whereas Harmonic Oscillator Model of aromaticity index (HOMA) provided data of aromaticity evolution as a derivative of the bridge proton position. The AIM-based topological analysis confirmed the presence of the intramolecular hydrogen bonding. In addition, using the theory, we were able to provide a quantitative illustration of bonding transformation: from covalent to the hydrogen. On the basis of HOMA analysis, we showed that the aromaticity of both rings is dependent on the location of the bridge proton. Further, the computed results were compared with experimental data available. Finally, ESIPT occurrence was compared for the three investigated kinds of hydrogen bridges, and competition between two bridges in one molecule was studied.
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Affiliation(s)
- Kacper Błaziak
- Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
| | - Jarosław J Panek
- Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
| | - Aneta Jezierska
- Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
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53
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Delfino I, Viola D, Cerullo G, Lepore M. Ultrafast excited-state charge-transfer dynamics in laccase type I copper site. Biophys Chem 2015; 200-201:41-7. [PMID: 25819432 DOI: 10.1016/j.bpc.2015.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 03/09/2015] [Accepted: 03/09/2015] [Indexed: 11/27/2022]
Abstract
Femtosecond pump-probe spectroscopy was used to investigate the excited state dynamics of the T1 copper site of laccase from Pleurotus ostreatus, by exciting its 600 nm charge transfer band with a 15-fs pulse and probing over a broad range in the visible region. The decay of the pump-induced ground-state bleaching occurs in a single step and is modulated by clearly visible oscillations. Global analysis of the two-dimensional differential transmission map shows that the excited state exponentially decays with a time constant of 375 fs, thus featuring a decay rate slower than those occurring in quite all the investigated T1 copper site proteins. The ultrashort pump pulse induces a vibrational coherence in the protein, which is mainly assigned to ground state activity, as expected in a system with fast excited state decay. Vibrational features are discussed also in comparison with the traditional resonance Raman spectrum of the enzyme. The results indicate that both excited state dynamics and vibrational modes associated with the T1 Cu laccase charge transfer have main characteristics similar to those of all the T1 copper site-containing proteins. On the other hand, the differences observed for laccase from P. ostreatus further confirm the peculiar hypothesized trigonal T1 Cu site geometry.
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Affiliation(s)
- Ines Delfino
- Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, Largo dell'Università snc, I-01100 Viterbo, Italy.
| | - Daniele Viola
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Giulio Cerullo
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Maria Lepore
- Dipartimento di Medicina Sperimentale, Seconda Università di Napoli, Via Costantinopoli 16, I-80100 Napoli, Italy
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54
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Kimani MM, Watts D, Graham LA, Rabinovich D, Yap GPA, Brumaghim JL. Dinuclear copper(i) complexes with N-heterocyclic thione and selone ligands: synthesis, characterization, and electrochemical studies. Dalton Trans 2015; 44:16313-24. [DOI: 10.1039/c5dt02232k] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report dinuclear copper(i) complexes with a variety of monodentate and bidentate thione- and selone-containing ligands. Cu(ii/i) potentials were tuned in a 470 mV range depending on the chalcogenone ligands.
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Affiliation(s)
| | - David Watts
- Department of Chemistry
- Clemson University
- Clemson
- USA
| | - Leigh A. Graham
- Department of Chemistry
- The University of North Carolina at Charlotte
- Charlotte
- USA
| | - Daniel Rabinovich
- Department of Chemistry
- The University of North Carolina at Charlotte
- Charlotte
- USA
| | - Glenn P. A. Yap
- Department of Chemistry and Biochemistry
- The University of Delaware
- Newark
- USA
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55
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Harding DJ, Phonsri W, Harding P, Sirirak J, Tangtirungrotechai Y, Webster RD, Adams H. Copper hydrotris(3,5-diphenylpyrazolyl)borate dithiocarbamates: mimicking green copper proteins. NEW J CHEM 2015. [DOI: 10.1039/c4nj01298d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three new copper hydrotris(pyrazolyl)borate dithiocarbamate complexes [TpPh2Cu(dtc)] which mimic green copper proteins are reported.
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Affiliation(s)
- David J. Harding
- Molecular Technology Research Unit Cell
- Walailak University
- Thasala
- Thailand
| | - Wasinee Phonsri
- Molecular Technology Research Unit Cell
- Walailak University
- Thasala
- Thailand
| | - Phimphaka Harding
- Molecular Technology Research Unit Cell
- Walailak University
- Thasala
- Thailand
| | - Jitnapa Sirirak
- Molecular Technology Research Unit Cell
- Walailak University
- Thasala
- Thailand
| | | | - Richard D. Webster
- Division of Chemistry and Biological Chemistry
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore 637371
| | - Harry Adams
- Department of Chemistry
- University of Sheffield
- Sheffield
- UK
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56
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Nakajima H, Miyazaki S, Itoh T, Hayamura M, Watanabe Y. Azurin–DNA Conjugate with the Binding Motif of a Transcriptional Regulator, CooA: CO-dependent Modulation of the Electron-transfer Reaction. CHEM LETT 2014. [DOI: 10.1246/cl.140284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
| | - Soji Miyazaki
- Research Centre of Materials Science, Nagoya University
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57
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Akkilic N, Kamran M, Stan R, Sanghamitra NJM. Voltage-controlled fluorescence switching of a single redox protein. Biosens Bioelectron 2014; 67:747-51. [PMID: 25103339 DOI: 10.1016/j.bios.2014.07.051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/14/2014] [Accepted: 07/22/2014] [Indexed: 02/07/2023]
Abstract
Heterogeneous electron transfer (ET) of the redox protein, wild-type azurin (wt-Az) from Pseudomonas aeruginosa, was monitored at the single-molecule (SM) level by fluorescence resonance energy transfer (FRET), one electron at a time. Azurin molecules were labeled with an organic fluorophore (Cy5), and the FRET-coupling between Cy5 and the redox center (copper) was used to study ET to a semi-transparent, 10nm thin gold electrode in an optical configuration. By using a confocal microscope and a bipotentiostat for control of the electrode potential, the oxidation and reduction processes of individual Az-Cy5 molecules were monitored. In the oxidized state of the redox center of the azurin molecule, the fluorescence emission of the covalently attached Cy5 was largely quenched by FRET ('off'-state), whereas the emission was recovered upon reduction ('on'-state). The work presented here, shows directly controlled single redox switching events of an individual redox protein and its thermodynamic dispersion. We show that the distribution of midpoint potentials (E0) of individual azurin molecules peaks at 45.7±0.5 mV with a full width at half maximum of 15 mV vs saturated calomel electrode (SCE).
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Affiliation(s)
- Namik Akkilic
- Leiden Institute of Physics, Huygens Laboratory, Leiden University, Leiden, The Netherlands.
| | - Muhammad Kamran
- Leiden Institute of Physics, Huygens Laboratory, Leiden University, Leiden, The Netherlands
| | - Razvan Stan
- Leiden Institute of Physics, Huygens Laboratory, Leiden University, Leiden, The Netherlands
| | - Nusrat J M Sanghamitra
- Leiden Institute of Physics, Huygens Laboratory, Leiden University, Leiden, The Netherlands
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58
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Roger M, Biaso F, Castelle CJ, Bauzan M, Chaspoul F, Lojou E, Sciara G, Caffarri S, Giudici-Orticoni MT, Ilbert M. Spectroscopic characterization of a green copper site in a single-domain cupredoxin. PLoS One 2014; 9:e98941. [PMID: 24932914 PMCID: PMC4059628 DOI: 10.1371/journal.pone.0098941] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/09/2014] [Indexed: 12/13/2022] Open
Abstract
Cupredoxins are widespread copper-binding proteins, mainly involved in electron transfer pathways. They display a typical rigid greek key motif consisting of an eight stranded β-sandwich. A fascinating feature of cupredoxins is the natural diversity of their copper center geometry. These geometry variations give rise to drastic changes in their color, such as blue, green, red or purple. Based on several spectroscopic and structural analyses, a connection between the geometry of their copper-binding site and their color has been proposed. However, little is known about the relationship between such diversity of copper center geometry in cupredoxins and possible implications for function. This has been difficult to assess, as only a few naturally occurring green and red copper sites have been described so far. We report herein the spectrocopic characterization of a novel kind of single domain cupredoxin of green color, involved in a respiratory pathway of the acidophilic organism Acidithiobacillus ferrooxidans. Biochemical and spectroscopic characterization coupled to bioinformatics analysis reveal the existence of some unusual features for this novel member of the green cupredoxin sub-family. This protein has the highest redox potential reported to date for a green-type cupredoxin. It has a constrained green copper site insensitive to pH or temperature variations. It is a green-type cupredoxin found for the first time in a respiratory pathway. These unique properties might be explained by a region of unknown function never found in other cupredoxins, and by an unusual length of the loop between the second and the fourth copper ligands. These discoveries will impact our knowledge on non-engineered green copper sites, whose involvement in respiratory chains seems more widespread than initially thought.
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Affiliation(s)
- Magali Roger
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Frédéric Biaso
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Cindy J. Castelle
- Department of Earth and Planetary Science, University of California, Berkeley, California, United States of America
| | - Marielle Bauzan
- Unité de Fermentation, Institut de Microbiologie de la Méditerranée, CNRS-FR 3479, Aix Marseille Université, Marseille, France
| | - Florence Chaspoul
- Unité Chimie Physique, Prévention des Risques et Nuisances Technologiques, Faculté de Pharmacie, CNRS-UMR 7263, Aix-Marseille Université, Marseille, France
| | - Elisabeth Lojou
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Giuliano Sciara
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Stefano Caffarri
- Unité de Biologie Végétale et Microbiologie Environnementales, CNRS-UMR 7265, CEA, Aix Marseille Université, Marseille, France
| | - Marie-Thérèse Giudici-Orticoni
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
| | - Marianne Ilbert
- Unité de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, CNRS-UMR7281, Aix-Marseille Université, Marseille, France
- * E-mail:
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59
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Shin S, Choi M, Williamson HR, Davidson VL. A simple method to engineer a protein-derived redox cofactor for catalysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1595-601. [PMID: 24858537 DOI: 10.1016/j.bbabio.2014.05.354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/14/2014] [Accepted: 05/16/2014] [Indexed: 10/25/2022]
Abstract
The 6×-Histidine tag which is commonly used for purification of recombinant proteins was converted to a catalytic redox-active center by incorporation of Co(2+). Two examples of the biological activity of this engineered protein-derived cofactor are presented. After inactivation of the natural diheme cofactor of MauG, it was shown that the Co(2+)-loaded 6×His-tag could substitute for the hemes in the H2O2-driven catalysis of tryptophan tryptophylquinone biosynthesis. To further demonstrate that the Co(2+)-loaded 6×His-tag could mediate long range electron transfer, it was shown that addition of H2O2 to the Co(2+)-loaded 6×His-tagged Cu(1+) amicyanin oxidizes the copper site which is 20Å away. These results provide proof of principle for this simple method by which to introduce a catalytic redox-active site into proteins for potential applications in research and biotechnology.
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Affiliation(s)
- Sooim Shin
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Moonsung Choi
- Seoul National University of Science and Technology, College of Energy and Biotechnology, Department of Optometry, Seoul, 139-743, Republic of Korea
| | - Heather R Williamson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA.
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60
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Liu J, Chakraborty S, Hosseinzadeh P, Yu Y, Tian S, Petrik I, Bhagi A, Lu Y. Metalloproteins containing cytochrome, iron-sulfur, or copper redox centers. Chem Rev 2014; 114:4366-469. [PMID: 24758379 PMCID: PMC4002152 DOI: 10.1021/cr400479b] [Citation(s) in RCA: 560] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Jing Liu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Saumen Chakraborty
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Igor Petrik
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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61
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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: 329] [Impact Index Per Article: 32.9] [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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62
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Dow BA, Sukumar N, Matos JO, Choi M, Schulte A, Tatulian SA, Davidson VL. The sole tryptophan of amicyanin enhances its thermal stability but does not influence the electronic properties of the type 1 copper site. Arch Biochem Biophys 2014; 550-551:20-7. [PMID: 24704124 DOI: 10.1016/j.abb.2014.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 10/25/2022]
Abstract
The cupredoxin amicyanin possesses a single tryptophan residue, Trp45. Its fluorescence is quenched when copper is bound even though it is separated by 10.1Å. Mutation of Trp45 to Ala, Phe, Leu and Lys resulted in undetectable protein expression. A W45Y amicyanin variant was isolated. The W45Y mutation did not alter the spectroscopic properties or intrinsic redox potential of amicyanin, but increased the pKa value for the pH-dependent redox potential by 0.5 units. This is due to a hydrogen-bond involving the His95 copper ligand which is present in reduced W45Y amicyanin but not in native amicyanin. The W45Y mutation significantly decreased the thermal stability of amicyanin, as determined by changes in the visible absorbance of oxidized amicyanin and in the circular dichroism spectra for oxidized, reduced and apo forms of amicyanin. Comparison of the crystal structures suggests that the decreased stability of W45Y amicyanin may be attributed to the loss of a strong interior hydrogen bond between Trp45 and Tyr90 in native amicyanin which links two of the β-sheets that comprise the overall structure of amicyanin. Thus, Trp45 is critical for stabilizing the structure of amicyanin but it does not influence the electronic properties of the copper which quenches its fluorescence.
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Affiliation(s)
- Brian A Dow
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States
| | - Narayanasami Sukumar
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Building 436E, Argonne National Laboratory, Argonne, IL 60439, United States.
| | - Jason O Matos
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States; Department of Physics, University of Central Florida, Orlando, FL 32816, United States
| | - Moonsung Choi
- Seoul National University of Science and Technology, College of Energy and Biotechnology, Department of Optometry, Seoul 139-743, Republic of Korea
| | - Alfons Schulte
- Department of Physics, University of Central Florida, Orlando, FL 32816, United States
| | - Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL 32816, United States
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States.
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63
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Ferroni FM, Marangon J, Neuman NI, Cristaldi JC, Brambilla SM, Guerrero SA, Rivas MG, Rizzi AC, Brondino CD. Pseudoazurin from Sinorhizobium meliloti as an electron donor to copper-containing nitrite reductase: influence of the redox partner on the reduction potentials of the enzyme copper centers. J Biol Inorg Chem 2014; 19:913-21. [DOI: 10.1007/s00775-014-1124-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 03/10/2014] [Indexed: 10/25/2022]
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64
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Clark KM, Yu Y, van der Donk WA, Blackburn N, Lu Y. Modulating the Copper-Sulfur Interaction in Type 1 Blue Copper Azurin by Replacing Cys112 with Nonproteinogenic Homocysteine. Inorg Chem Front 2014; 1:153-158. [PMID: 24707355 PMCID: PMC3972132 DOI: 10.1039/c3qi00096f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The Cu-SCys interaction is known to play a dominant role in defining the type 1 (T1) blue copper center with respect to both its electronic structure and electron transfer function. Despite this importance, its role has yet to be probed by mutagenesis studies without dramatic change of its T1 copper character. We herein report replacement of the conserved Cys112 in azurin with the nonproteinogenic amino acid homocysteine. Based on electronic absorption, electron paramagnetic resonance, and extended x-ray absorption fine structural spectroscopic studies, this variant displays typical type 1 copper site features. Surprisingly, instead of increasing the strength of the Cu-sulfur interaction by the introduction of the extra methylene group, the Cys112Hcy azurin showed a decrease in the covalent interaction between SHcy and Cu(II) when compared with the WT SCys-Cu(II) interaction. This is likely due to geometric adjustment of the center that resulted in the copper ion moving out of the trigonal plane defined by two histidines and one Hcy and closer to Met121. These structural changes resulted in an increase of reduction potential by 35 mV, consistent with lower Cu-S covalency. These results suggest that the Cu-SCys interaction is close to being optimal in native blue copper protein. It also demonstrates the power of using nonproteinogenic amino acids in addressing important issues in bioinorganic chemistry.
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Affiliation(s)
- Kevin M Clark
- University of Illinois-Urbana, Department of Biochemistry, Urbana, IL61801; USA
| | - Yang Yu
- University of Illinois-Urbana. Center for Biophysics and Computational Biology, Urbana, IL 61801, USA
| | - Wilfred A van der Donk
- University of Illinois-Urbana, Department of Biochemistry, Urbana, IL61801; USA
- University of Illinois-Urbana. Center for Biophysics and Computational Biology, Urbana, IL 61801, USA
- University of Illinois-Urbana. Department of Chemistry, Urbana, IL 61801, USA
- Howard Hughes Medical Institute, Urbana, IL 61801, USA
| | - Ninian Blackburn
- Oregon Health & Sciences University, Institute of Environmental Health, Beaverton, OR 97006, USA
| | - Yi Lu
- University of Illinois-Urbana, Department of Biochemistry, Urbana, IL61801; USA
- University of Illinois-Urbana. Center for Biophysics and Computational Biology, Urbana, IL 61801, USA
- University of Illinois-Urbana. Department of Chemistry, Urbana, IL 61801, USA
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65
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Kalva S, Azhagiya Singam ER, Rajapandian V, Saleena LM, Subramanian V. Discovery of potent inhibitor for matrix metalloproteinase-9 by pharmacophore based modeling and dynamics simulation studies. J Mol Graph Model 2014; 49:25-37. [PMID: 24473069 DOI: 10.1016/j.jmgm.2013.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 12/17/2013] [Accepted: 12/20/2013] [Indexed: 12/21/2022]
Abstract
Matrix metalloproteinase-9 (MMP-9) is an attractive target for anticancer therapy. In the present study ligand based pharmacophore modeling was performed to elucidate the structural elements for a diverse class of MMP-9 inhibitors. The pharmacophore model was validated through Güner-Henry (GH) scoring method. The final pharmacophore model consisted of three hydrogen bond acceptors (HBA), and two ring aromatic regions (RA). This model was utilized to screen the natural compound database to seek novel compounds as MMP-9 inhibitors. The identified hits were validated using molecular docking and molecular dynamics simulation studies. Finally, one compound named Hinokiflavone from Juniperus communis had high binding free energy of -26.54kJ/mol compared with the known inhibitors of MMP-9. Cytotoxicity for hinokiflavone was evaluated by MTT assay. Inhibition of MMP-9 in the presence of hinokiflavone was detected by gelatin zymography and gelatinolytic inhibition assay. Results revealed that the natural compounds derived based on the developed pharmacophore model would be useful for further design and development of MMP-9 inhibitors.
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Affiliation(s)
- Sukesh Kalva
- Department of Bioinformatics, SRM University, Kattankulathur, Kancheepuram District 603 203, India
| | - E R Azhagiya Singam
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V Rajapandian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - Lilly M Saleena
- Department of Bioinformatics, SRM University, Kattankulathur, Kancheepuram District 603 203, India.
| | - V Subramanian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India.
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66
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Gajewska MJ, Ching WM, Wen YS, Hung CH. Synthesis, structure, and catecholase activity of bispyrazolylacetate copper(ii) complexes. Dalton Trans 2014; 43:14726-36. [DOI: 10.1039/c4dt01467g] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heteroleptic copper(ii) complexes containing bis(3,5-di-t-butylpyrazol-1-yl)acetate and nitrogen heterocyclic co-ligands identified the influence of co-ligands on the conformation and catecholase-like catalytic activity.
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Affiliation(s)
| | - Wei-Min Ching
- Institute of Chemistry
- Academia Sinica
- Taipei 105, Taiwan
| | - Yuh-Sheng Wen
- Institute of Chemistry
- Academia Sinica
- Taipei 105, Taiwan
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67
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Paltrinieri L, Borsari M, Battistuzzi G, Sola M, Dennison C, de Groot BL, Corni S, Bortolotti CA. How the dynamics of the metal-binding loop region controls the acid transition in cupredoxins. Biochemistry 2013; 52:7397-404. [PMID: 24063705 DOI: 10.1021/bi400860n] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many reduced cupredoxins undergo a pH-dependent structural rearrangement, triggered by protonation of the His ligand belonging to the C-terminal hydrophobic loop, usually termed the acid transition. At variance with several members of the cupredoxin family, the acid transition is not observed for azurin (AZ). We have addressed this issue by performing molecular dynamics simulations of AZ and four mutants, in which the C-terminal loop has been replaced with those of other cupredoxins or with polyalanine loops. All of the loop mutants undergo the acid transition in the pH range of 4.4-5.5. The main differences between AZ and its loop mutants are the average value of the active site solvent accessible surface area and the extent of its fluctuations with time, together with an altered structure of the water layer around the copper center. Using functional mode analysis, we found that these variations arise from changes in nonbonding interactions in the second coordination sphere of the copper center, resulting from the loop mutation. Our results strengthen the view that the dynamics at the site relevant for function and its surroundings are crucial for protein activity and for metal-containing electron transferases.
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Affiliation(s)
- Licia Paltrinieri
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , via Campi 183, 41125 Modena, Italy
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68
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Beloglazkina EK, Majouga AG, Mironov AV, Yudina AV, Moiseeva AA, Lebedeva MA, Khlobystov AN, Zyk NV. Synthesis, X-ray crystallography and electrochemistry of three novel copper complexes with imidazole-containing hydantoin and thiohydantoins. Polyhedron 2013. [DOI: 10.1016/j.poly.2013.07.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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69
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Isomorphic deactivation of a Pseudomonas aeruginosa oxidoreductase: The crystal structure of Ag(I) metallated azurin at 1.7 Å. J Inorg Biochem 2013; 128:11-6. [PMID: 23911566 DOI: 10.1016/j.jinorgbio.2013.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 07/05/2013] [Accepted: 07/08/2013] [Indexed: 11/21/2022]
Abstract
Multiple biophysical methods demonstrate that silver effectively metallates Pseudomonas aeruginosa apo-azurin in solution. X-ray crystallography of the silver-modified protein reveals that silver binds to azurin at the traditional copper mediated active site with nearly identical geometry. Cyclic voltammetry indicates that the silver adduct is redox inert. Our results suggest that a potential mechanism for the microbial toxicity of silver is the deactivation of copper oxidoreductases by the effective binding and structural mimicry by silver without the corresponding function.
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70
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Thapper A, Rizzi AC, Brondino CD, Wedd AG, Pais RJ, Maiti BK, Moura I, Pauleta SR, Moura JJG. Copper-substituted forms of the wild type and C42A variant of rubredoxin. J Inorg Biochem 2013; 127:232-7. [PMID: 23829948 DOI: 10.1016/j.jinorgbio.2013.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 05/03/2013] [Accepted: 06/05/2013] [Indexed: 11/16/2022]
Abstract
In order to gain insights into the interplay between Cu(I) and Cu(II) in sulfur-rich protein environments, the first preparation and characterization of copper-substituted forms of the wild-type rubredoxin (Rd) from Desulfovibrio vulgaris Hildenborough are reported, as well as those of its variant C42A-Rd. The initial products appear to be tetrahedral Cu(I)(S-Cys)n species for the wild type (n=4) and the variant C42A (n=3, with an additional unidentified ligand). These species are unstable to aerial oxidation to products, whose properties are consistent with square planar Cu(II)(S-Cys)n species. These Cu(II) intermediates are susceptible to auto-reduction by ligand S-Cys to produce stable Cu(I) final products. The original Cu(I) center in the wild-type system can be regenerated by reduction, suggesting that the active site can accommodate Cu(I)(S-Cys)2 and Cys-S-S-Cys fragments in the final product. The absence of one S-Cys ligand prevents similar regeneration in the C42A-Rd system. These results emphasize the redox instability of Cu(II)-(S-Cys)n centers.
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Affiliation(s)
- Anders Thapper
- Department of Photochemistry and Molecular Science, Uppsala University, P.O. Box 523, S-751 20 Uppsala, Sweden
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71
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Designed azurins show lower reorganization free energies for intraprotein electron transfer. Proc Natl Acad Sci U S A 2013; 110:10536-40. [PMID: 23759745 DOI: 10.1073/pnas.1215081110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Low reorganization free energies are necessary for fast electron transfer (ET) reactions. Hence, rational design of redox proteins with lower reorganization free energies has been a long-standing challenge, promising to yield a deeper understanding of the underlying principles of ET reactivity and to enable potential applications in different energy conversion systems. Herein we report studies of the intramolecular ET from pulse radiolytically produced disulfide radicals to Cu(II) in rationally designed azurin mutants. In these mutants, the copper coordination sphere has been fine-tuned to span a wide range of reduction potentials while leaving the metal binding site effectively undisrupted. We find that the reorganization free energies of ET within the mutants are indeed lower than that of WT azurin, increasing the intramolecular ET rate constants almost 10-fold: changes that are correlated with increased flexibility of their copper sites. Moreover, the lower reorganization free energy results in the ET rate constants reaching a maximum value at higher driving forces, as predicted by the Marcus theory.
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72
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Warren JJ, Gray HB, Winkler JR, Kozak JJ. A Euclidean Perspective on the Unfolding of Azurin: Spatial Correlations. Mol Phys 2013; 111:922-929. [PMID: 23853392 PMCID: PMC3708666 DOI: 10.1080/00268976.2012.758324] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We investigate the stability to structural perturbation of Pseudomonas aeruginosa azurin using a previously developed geometric model. Our analysis considers Ru(2,2',6',2″-terpyridine)(1,10-phenanthroline)(His83)-labeled wild-type azurin and five variants with mutations to Cu-ligating residues. We find that in the early stages of unfolding, the β-strands exhibit the most structural stability. The conserved residues comprising the hydrophobic core are dislocated only after nearly complete unfolding of the β-barrel. Attachment of the Ru-complex at His83 does not destabilize the protein fold, despite causing some degree of structural rearrangement. Notably, replacing the Cys112 and/or Met121 Cu ligands does not affect the conformational integrity of the protein. Notably, these results are in accord with experimental evidence, as well as molecular dynamics simulations of the denaturation of azurin.
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Affiliation(s)
- Jeffrey J. Warren
- Beckman Institute, California Institute of Technology, Pasadena CA 91125
| | - Harry B. Gray
- Beckman Institute, California Institute of Technology, Pasadena CA 91125
| | - Jay R. Winkler
- Beckman Institute, California Institute of Technology, Pasadena CA 91125
| | - John J. Kozak
- DePaul University, 243 South Wabash Ave., Chicago, IL 60604-8875
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73
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Paltrinieri L, Borsari M, Ranieri A, Battistuzzi G, Corni S, Bortolotti CA. The Active Site Loop Modulates the Reorganization Energy of Blue Copper Proteins by Controlling the Dynamic Interplay with Solvent. J Phys Chem Lett 2013; 4:710-715. [PMID: 26281923 DOI: 10.1021/jz302125k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding the factors governing the rate of electron transfer processes in proteins is crucial not only to a deeper understanding of redox processes in living organisms but also for the design of efficient devices featuring biological molecules. Here, molecular dynamics simulations performed on native azurin and four chimeric cupredoxins allow for the calculation of the reorganization energy and of structure-related quantities that were used to clarify the molecular determinants to the dynamics/function relationship in blue copper proteins. We find that the dynamics of the small, metal-binding loop region controls the outer-sphere reorganization energy not only by determining the exposure of the active site to solvent but also through the modulation of the redox-dependent rearrangement of the whole protein scaffold and of the surrounding water molecules.
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Affiliation(s)
| | | | | | | | - Stefano Corni
- ¶CNR-Nano Institute of Nanoscience, via Campi 213/A, 41125 Modena, Italy
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74
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Gomila A, Le Poul N, Kerbaol JM, Cosquer N, Triki S, Douziech B, Conan F, Le Mest Y. Electrochemical behavior and dioxygen reactivity of tripodal dinuclear copper complexes linked by unsaturated rigid spacers. Dalton Trans 2013; 42:2238-53. [DOI: 10.1039/c2dt31456h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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75
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Wilson TD, Yu Y, Lu Y. Understanding copper-thiolate containing electron transfer centers by incorporation of unnatural amino acids and the CuA center into the type 1 copper protein azurin. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.06.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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76
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Allen S, Badarau A, Dennison C. The influence of protein folding on the copper affinities of trafficking and target sites. Dalton Trans 2012; 42:3233-9. [PMID: 23169585 DOI: 10.1039/c2dt32166a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The relative influence of protein unfolding on the Cu(I) affinity of trafficking and target sites for copper has been determined. For the copper metallochaperone Atx1 from Synechocystis PCC 6803 (a cyanobacterium), Saccharomyces cerevisiae and humans unfolding in urea results in a decrease in the Cu(I) affinity from (4-5) × 10(17) M(-1) to (1-3) × 10(16) M(-1) at pH 7. The affinities of the unfolded Atx1s are similar to those for CXXC-containing peptides. Partial unfolding, due to the loop 5 His61Lys mutation in Synechocystis Atx1, gives rise to a more limited decrease in Cu(I) affinity. For the copper target protein plastocyanin from Synechocystis, chemical unfolding results in the Cu(I) affinity decreasing by 5-orders of magnitude. This differential influence of protein unfolding on Cu(I) affinity is due to a more complex copper site structure in the target protein, including numerous interactions of non-coordinating residues with ligating amino acids. This second-coordination sphere is much simpler in the Atx1s with the main interaction provided by the loop 5 residue that tunes the Cu(I) affinity by altering the pK(a) of the C-terminal Cys ligand of the CXXC motif. This interaction and others are absent in the unfolded Atx1s and the two Cys ligands have pK(a) values reminiscent of free thiols (>8) resulting in lowered Cu(I) affinities at pH 7. Residues close to the active site of the thiol-disulfide oxidoreductase thioredoxin appear to lower the Cu(I) affinity of its CXXC motif to 3.1 × 10(15) M(-1) at pH 7, presumably to prevent copper binding in vivo. The structure of a copper site, including the number and relative position of ligands in the primary structure and the complexity of the second-coordination sphere, results in dramatically different effects of unfolding on Cu(I) affinity that has important implications for copper homeostasis.
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Affiliation(s)
- Stephen Allen
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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77
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Warren JJ, Lancaster KM, Richards JH, Gray HB. Inner- and outer-sphere metal coordination in blue copper proteins. J Inorg Biochem 2012; 115:119-26. [PMID: 22658756 PMCID: PMC3434318 DOI: 10.1016/j.jinorgbio.2012.05.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 04/30/2012] [Accepted: 05/01/2012] [Indexed: 10/28/2022]
Abstract
Blue copper proteins (BCPs) comprise classic cases of Nature's profound control over the electronic structures and chemical reactivity of transition metal ions. Early studies of BCPs focused on their inner coordination spheres, that is, residues that directly coordinate Cu. Equally important are the electronic and geometric perturbations to these ligands provided by the outer coordination sphere. In this tribute to Hans Freeman, we review investigations that have advanced the understanding of how inner-sphere and outer-sphere coordination affects biological Cu properties.
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Affiliation(s)
- Jeffrey J Warren
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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78
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Variations in methanobactin structure influences copper utilization by methane-oxidizing bacteria. Proc Natl Acad Sci U S A 2012; 109:8400-4. [PMID: 22582172 DOI: 10.1073/pnas.1112921109] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Methane-oxidizing bacteria are nature's primary biological mechanism for suppressing atmospheric levels of the second-most important greenhouse gas via methane monooxygenases (MMOs). The copper-containing particulate enzyme is the most widespread and efficient MMO. Under low-copper conditions methane-oxidizing bacteria secrete the small copper-binding peptide methanobactin (mbtin) to acquire copper, but how variations in the structures of mbtins influence copper metabolism and species selection are unknown. Methanobactins have been isolated from Methylocystis strains M and hirsuta CSC1, organisms that can switch to using an iron-containing soluble MMO when copper is limiting, and the nonswitchover Methylocystis rosea. These mbtins are shorter, and have different amino acid compositions, than the characterized mbtin from Methylosinus trichosporium OB3b. A coordinating pyrazinedione ring in the Methylocystis mbtins has little influence on the Cu(I) site structure. The Methylocystis mbtins have a sulfate group that helps stabilize the Cu(I) forms, resulting in affinities of approximately 10(21) M(-1). The Cu(II) affinities vary over three orders of magnitude with reduction potentials covering approximately 250 mV, which may dictate the mechanism of intracellular copper release. Copper uptake and the switchover from using the iron-containing soluble MMO to the copper-containing particulate enzyme is faster when mediated by the native mbtin, suggesting that the amino acid sequence is important for the interaction of mbtins with receptors. The differences in structures and properties of mbtins, and their influence on copper utilization by methane-oxidizing bacteria, have important implications for the ecology and global function of these environmentally vital organisms.
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79
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Potapov A, Lancaster KM, Richards JH, Gray HB, Goldfarb D. Spin delocalization over type zero copper. Inorg Chem 2012; 51:4066-75. [PMID: 22432748 DOI: 10.1021/ic202336m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hard-ligand, high-potential copper sites have been characterized in double mutants of Pseudomonas aeruginosa azurin (C112D/M121X (X = L, F, I)). These sites feature a small A(zz)(Cu) splitting in the EPR spectrum together with enhanced electron transfer activity. Due to these unique properties, these constructs have been called "type zero" copper sites. In contrast, the single mutant, C112D, features a large A(zz)(Cu) value characteristic of the typical type 2 Cu(II). In general, A(zz)(Cu) comprises contributions from Fermi contact, spin dipolar, and orbital dipolar terms. In order to understand the origin of the low A(zz)(Cu) value of type zero Cu(II), we explored in detail its degree of covalency, as manifested by spin delocalization over its ligands, which affects A(zz)(Cu) through the Fermi contact and spin dipolar contributions. This was achieved by the application of several complementary EPR hyperfine spectroscopic techniques at X- and W-band (∼9.5 and 95 GHz, respectively) frequencies to map the ligand hyperfine couplings. Our results show that spin delocalization over the ligands in type zero Cu(II) is different from that of type 2 Cu(II) in the single C112D mutant. The (14)N hyperfine couplings of the coordinated histidine nitrogens are smaller by about 25-40%, whereas that of the (13)C carboxylate of D112 is about 50% larger. From this comparison, we concluded that the spin delocalization of type zero copper over its ligands is not dramatically larger than in type 2 C112D. Therefore, the reduced A(zz)(Cu) value of type zero Cu(II) is largely attributable to an increased orbital dipolar contribution that is related to its larger g(zz) value, as a consequence of the distorted tetrahedral geometry. The increased spin delocalization over the D112 carboxylate in type zero mutants compared to type 2 C112D suggests that electron transfer paths involving this residue are enhanced.
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Affiliation(s)
- Alexey Potapov
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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80
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Guzzi R, Sportelli L, Yanagisawa S, Li C, Kostrz D, Dennison C. The influence of active site loop mutations on the thermal stability of azurin from Pseudomonas aeruginosa. Arch Biochem Biophys 2012; 521:18-23. [PMID: 22446157 DOI: 10.1016/j.abb.2012.03.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/05/2012] [Accepted: 03/06/2012] [Indexed: 10/28/2022]
Abstract
The copper site and overall structures of azurin (AZ) variants in which the amicyanin (AMI) and plastocyanin (PC) metal binding loops have been introduced, AZAMI and AZPC, respectively, are similar to that of AZ, whereas the loop conformations resemble those in the native proteins. To assess the influence of these loop mutations on stability, the thermal unfolding of AZAMI and AZPC has been investigated by differential scanning calorimetry, absorption and fluorescence spectroscopy. The calorimetric profiles of both variants exhibit a complex shape consisting of two endothermic peaks and an exothermic peak. The temperature of the maximum heat of absorption for the single endothermic peak is 82.7°C for AZ, whereas for AZAMI and AZPC the most intense endothermic peaks are at 74.9 and 68.1°C comparable to values for AMI and PC, respectively. Denaturation investigated using the temperature dependence of the absorbance at ∼600nm and Trp emission, also demonstrates decreased stability for both loop mutants. The thermal transition between the native and the denaturated states is irreversible, scan rate dependent and consistent with the two-state irreversible model. The structure of the active-site loop has a dramatic effect on the kinetic stability and the unfolding pathway of cupredoxins.
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Affiliation(s)
- Rita Guzzi
- Molecular Biophysics Laboratory and CNISM Unit, Department of Physics, University of Calabria, Ponte P. Bucci, Cubo 31C, 87036 Rende (CS), Italy.
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81
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Wilson TD, Savelieff MG, Nilges MJ, Marshall NM, Lu Y. Kinetics of Copper Incorporation into a Biosynthetic Purple CuA Azurin: Characterization of Red, Blue, and a New Intermediate Species. J Am Chem Soc 2011; 133:20778-92. [DOI: 10.1021/ja205281t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Tiffany D. Wilson
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Masha G. Savelieff
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Mark J. Nilges
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Nicholas M. Marshall
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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82
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Type 1 copper site synthetic model complexes with increased redox potentials. J Biol Inorg Chem 2011; 17:285-91. [PMID: 21960257 DOI: 10.1007/s00775-011-0849-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
Reactions of NaSCPh(3) with (R(3)tacn)Cu(OTf)(2) (R is Me, iPr; tacn is 1,4,7-triazacyclononane; OTf is CF(3)SO(3)(-)) yield blue complexes identified as ((R(3)tacn)CuSCPh(3))(OTf) on the basis of UV-vis, resonance Raman, and electron paramagnetic resonance (EPR) spectroscopy and electrospray ionization mass spectrometry. These complexes exhibit spectroscopic properties typical of type 1 copper sites in proteins, including diagnostic Sπ → Cu(d(x(2)-y(2))) ligand-to-metal charge transfer transitions at approximately 610-630 nm and small A(||) values in EPR spectra of less than 100 × 10(-4) cm(-1). Cyclic voltammetry experiments revealed redox potentials for the complexes similar to those of several low-potential type 1 copper proteins (e.g., azurin, stellacyanin) and approximately 0.5 V higher than those of previously reported model compounds. Thus, the new complexes mimic key aspects of both the structure and the function of type 1 copper sites.
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83
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Sukumar N, Choi M, Davidson VL. Replacement of the axial copper ligand methionine with lysine in amicyanin converts it to a zinc-binding protein that no longer binds copper. J Inorg Biochem 2011; 105:1638-44. [PMID: 22071089 DOI: 10.1016/j.jinorgbio.2011.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/12/2011] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
The mutation of the axial ligand of the type I copper protein amicyanin from Met to Lys results in a protein that is spectroscopically invisible and redox inactive. M98K amicyanin acts as a competitive inhibitor in the reaction of native amicyanin with methylamine dehydrogenase indicating that the M98K mutation has not affected the affinity for its natural electron donor. The crystal structure of M98K amicyanin reveals that its overall structure is very similar to native amicyanin but that the type I binding site is occupied by zinc. Anomalous difference Fourier maps calculated using the data collected around the absorption edges of copper and zinc confirm the presence of Zn(2+) at the type I site. The Lys98 NZ donates a hydrogen bond to a well-ordered water molecule at the type I site which enhances the ability of Lys98 to provide a ligand for Zn(2+). Attempts to reconstitute M98K apoamicyanin with copper resulted in precipitation of the protein. The fact that the M98K mutation generated such a selective zinc-binding protein was surprising as ligation of zinc by Lys is rare and this ligand set is unique for zinc.
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Affiliation(s)
- Narayanasami Sukumar
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL 60439, USA.
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84
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Rajapandian V, Subramanian V. Calculations on the Structure and Spectral Properties of Cytochrome c551 Using DFT and ONIOM Methods. J Phys Chem A 2011; 115:2866-76. [DOI: 10.1021/jp110983v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Rajapandian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
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85
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Choi M, Sukumar N, Mathews FS, Liu A, Davidson VL. Proline 96 of the copper ligand loop of amicyanin regulates electron transfer from methylamine dehydrogenase by positioning other residues at the protein-protein interface. Biochemistry 2011; 50:1265-73. [PMID: 21268585 DOI: 10.1021/bi101794y] [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
Amicyanin is a type 1 copper protein that serves as an electron acceptor for methylamine dehydrogenase (MADH). The site of interaction with MADH is a "hydrophobic patch" of amino acid residues including those that comprise a "ligand loop" that provides three of the four copper ligands. Three prolines are present in this region. Pro94 of the ligand loop was previously shown to strongly influence the redox potential of amicyanin but not affinity for MADH or mechanism of electron transfer (ET). In this study Pro96 of the ligand loop was mutated. P96A and P96G mutations did not affect the spectroscopic or redox properties of amicyanin but increased the K(d) for complex formation with MADH and altered the kinetic mechanism for the interprotein ET reaction. Values of reorganization energy (λ) and electronic coupling (H(AB)) for the ET reaction with MADH were both increased by the mutation, indicating that the true ET reaction observed with native amicyanin was now gated by or coupled to a reconfiguration of the proteins within the complex. The crystal structure of P96G amicyanin was very similar to that of native amicyanin, but notably, in addition to the change in Pro96, the side chains of residues Phe97 and Arg99 were oriented differently. These two residues were previously shown to make contacts with MADH that were important for stabilizing the amicyanin-MADH complex. The values of K(d), λ, and H(AB) for the reactions of the Pro96 mutants with MADH are remarkably similar to those obtained previously for P52G amicyanin. Mutation of this proline, also in the hydrophobic patch, caused reorientation of the side chain of Met51, another reside that interacted with MADH and caused a change in the kinetic mechanism of ET from MADH. These results show that proline residues near the copper site play key roles in positioning other amino acid residues at the amicyanin-MADH interface not only for specific binding to the redox protein partner but also to optimize the orientation of proteins for interprotein ET.
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Affiliation(s)
- Moonsung Choi
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, United States
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86
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Choi M, Davidson VL. Cupredoxins--a study of how proteins may evolve to use metals for bioenergetic processes. Metallomics 2011; 3:140-51. [PMID: 21258692 DOI: 10.1039/c0mt00061b] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cupredoxins are small proteins that contain type I copper centers, which are ubiquitous in nature. They function as electron transfer shuttles between proteins. This review of the structure and properties of native cupredoxins, and those modified by site-directed mutagenesis, illustrates how these proteins may have evolved to specifically bind copper, develop recognition sites for specific redox partners, tune redox potential for a particular function, and allow for efficient electron transfer through the protein matrix. This is relevant to the general understanding of the roles of metals in energy metabolism, respiration and photosynthesis.
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Affiliation(s)
- Moonsung Choi
- Department of Biochemistry, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216-4505, USA
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87
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Incorporation of the red copper nitrosocyanin binding loop into blue copper azurin. J Biol Inorg Chem 2010; 16:473-80. [DOI: 10.1007/s00775-010-0746-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 11/24/2010] [Indexed: 10/18/2022]
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88
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Li C, Sato K, Monari S, Salard I, Sola M, Banfield MJ, Dennison C. Metal-Binding Loop Length Is a Determinant of the pKa of a Histidine Ligand at a Type 1 Copper Site. Inorg Chem 2010; 50:482-8. [DOI: 10.1021/ic101413e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Chan Li
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katsuko Sato
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Stefano Monari
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41125 Modena, Italy
| | - Isabelle Salard
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Marco Sola
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41125 Modena, Italy
| | - Mark J. Banfield
- Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, U.K
| | - Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
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89
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Tisato F, Marzano C, Porchia M, Pellei M, Santini C. Copper in diseases and treatments, and copper-based anticancer strategies. Med Res Rev 2010; 30:708-49. [PMID: 19626597 DOI: 10.1002/med.20174] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Copper is found in all living organisms and is a crucial trace element in redox chemistry, growth and development. It is important for the function of several enzymes and proteins involved in energy metabolism, respiration, and DNA synthesis, notably cytochrome oxidase, superoxide dismutase, ascorbate oxidase, and tyrosinase. The major functions of copper-biological molecules involve oxidation-reduction reactions in which they react directly with molecular oxygen to produce free radicals. Therefore, copper requires tightly regulated homeostatic mechanisms to ensure adequate supplies without any toxic effects. Overload or deficiency of copper is associated, respectively, with Wilson disease (WD) and Menkes disease (MD), which are of genetic origin. Researches on Menkes and Wilson disorders have provided useful insights in the field of copper homeostasis and in particular into the understanding of intracellular trafficking and distribution of copper at molecular levels. Therapies based on metal supplementation with copper histidine or removal of copper excess by means of specific copper chelators are currently effective in treating MD and WD, respectively. Copper chelation therapy is now attracting much attention for the investigation and treatment of various neurodegenerative disorders such as Alzheimer, Parkinson and CreutzfeldtJakob. An excess of copper appears to be an essential co-factor for angiogenesis. Moreover, elevated levels of copper have been found in many types of human cancers, including prostate, breast, colon, lung, and brain. On these basis, the employment of copper chelators has been reported to be of therapeutic value in the treatment of several types of cancers as anti-angiogenic molecules. More recently, mixtures of copper chelators with copper salts have been found to act as efficient proteasome inhibitors and apoptosis inducers, specifically in cancer cells. Moreover, following the worldwide success of platinum(II) compounds in cancer chemotherapy, several families of individual copper complexes have been studied as potential antitumor agents. These investigations, revealing the occurrence of mechanisms of action quite different from platinum drugs, head toward the development of new anticancer metallodrugs with improved specificity and decreased toxic side effects.
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90
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Castelle C, Ilbert M, Infossi P, Leroy G, Giudici-Orticoni MT. An unconventional copper protein required for cytochrome c oxidase respiratory function under extreme acidic conditions. J Biol Chem 2010; 285:21519-25. [PMID: 20442397 PMCID: PMC2898452 DOI: 10.1074/jbc.m110.131359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 04/30/2010] [Indexed: 11/06/2022] Open
Abstract
Very little is known about the processes used by acidophile organisms to preserve stability and function of respiratory pathways. Here, we reveal a potential strategy of these organisms for protecting and keeping functional key enzymes under extreme conditions. Using Acidithiobacillus ferrooxidans, we have identified a protein belonging to a new cupredoxin subfamily, AcoP, for "acidophile CcO partner," which is required for the cytochrome c oxidase (CcO) function. We show that it is a multifunctional copper protein with at least two roles as follows: (i) as a chaperone-like protein involved in the protection of the Cu(A) center of the CcO complex and (ii) as a linker between the periplasmic cytochrome c and the inner membrane cytochrome c oxidase. It could represent an interesting model for investigating the multifunctionality of proteins known to be crucial in pathways of energy metabolism.
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Affiliation(s)
- Cindy Castelle
- From the Laboratoire de Bioénergétique et Ingénierie des Protéines, IMM-CNRS, 13402 Marseille Cedex 20, France
| | - Marianne Ilbert
- From the Laboratoire de Bioénergétique et Ingénierie des Protéines, IMM-CNRS, 13402 Marseille Cedex 20, France
| | - Pascale Infossi
- From the Laboratoire de Bioénergétique et Ingénierie des Protéines, IMM-CNRS, 13402 Marseille Cedex 20, France
| | - Gisèle Leroy
- From the Laboratoire de Bioénergétique et Ingénierie des Protéines, IMM-CNRS, 13402 Marseille Cedex 20, France
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91
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Rajapandian V, Hakkim V, Subramanian V. Molecular Dynamics Studies on Native, Loop-Contracted, and Metal Ion-Substituted Azurins. J Phys Chem B 2010; 114:8474-86. [DOI: 10.1021/jp911301v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V. Rajapandian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Hakkim
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
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92
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Najmudin S, Pauleta SR, Moura I, Romão MJ. The 1.4 A resolution structure of Paracoccus pantotrophus pseudoazurin. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:627-35. [PMID: 20516588 PMCID: PMC2882758 DOI: 10.1107/s1744309110013989] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 04/15/2010] [Indexed: 11/10/2022]
Abstract
Pseudoazurins are small type 1 copper proteins that are involved in the flow of electrons between various electron donors and acceptors in the bacterial periplasm, mostly under denitrifying conditions. The previously determined structure of Paracoccus pantotrophus pseudoazurin in the oxidized form was improved to a nominal resolution of 1.4 A, with R and R(free) values of 0.188 and 0.206, respectively. This high-resolution structure makes it possible to analyze the interactions between the monomers and the solvent structure in detail. Analysis of the high-resolution structure revealed the structural regions that are responsible for monomer-monomer recognition during dimer formation and for protein-protein interaction and that are important for partner recognition. The pseudoazurin structure was compared with other structures of various type 1 copper proteins and these were grouped into families according to similarities in their secondary structure; this may be useful in the annotation of copper proteins in newly sequenced genomes and in the identification of novel copper proteins.
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Affiliation(s)
- Shabir Najmudin
- REQUIMTE, Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Sofia R. Pauleta
- REQUIMTE, Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Isabel Moura
- REQUIMTE, Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Maria J. Romão
- REQUIMTE, Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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93
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Crowley PB, Matias PM, Mi H, Firbank SJ, Banfield MJ, Dennison C. Regulation of protein function: crystal packing interfaces and conformational dimerization. Biochemistry 2010; 47:6583-9. [PMID: 18479147 DOI: 10.1021/bi800125h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The accepted view of interprotein electron transport involves molecules diffusing between donor and acceptor redox sites. An emerging alternative hypothesis is that efficient long-range electron transport can be achieved through proteins arranged in supramolecular assemblies. In this study, we have investigated the crystal packing interfaces in three crystal forms of plastocyanin, an integral component of the photosynthetic electron transport chain, and discuss their potential relevance to in vivo supramolecular assemblies. Symmetry-related protein chains within these crystals have Cu-Cu separations of <25 A, a distance that readily supports electron transfer. In one structure, the plastocyanin molecule exists in two forms in which a backbone displacement coupled with side chain rearrangements enables the modulation of protein-protein interfaces.
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Affiliation(s)
- Peter B Crowley
- UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
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94
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Rationally tuning the reduction potential of a single cupredoxin beyond the natural range. Nature 2009; 462:113-6. [PMID: 19890331 DOI: 10.1038/nature08551] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/30/2009] [Indexed: 11/08/2022]
Abstract
Redox processes are at the heart of numerous functions in chemistry and biology, from long-range electron transfer in photosynthesis and respiration to catalysis in industrial and fuel cell research. These functions are accomplished in nature by only a limited number of redox-active agents. A long-standing issue in these fields is how redox potentials are fine-tuned over a broad range with little change to the redox-active site or electron-transfer properties. Resolving this issue will not only advance our fundamental understanding of the roles of long-range, non-covalent interactions in redox processes, but also allow for design of redox-active proteins having tailor-made redox potentials for applications such as artificial photosynthetic centres or fuel cell catalysts for energy conversion. Here we show that two important secondary coordination sphere interactions, hydrophobicity and hydrogen-bonding, are capable of tuning the reduction potential of the cupredoxin azurin over a 700 mV range, surpassing the highest and lowest reduction potentials reported for any mononuclear cupredoxin, without perturbing the metal binding site beyond what is typical for the cupredoxin family of proteins. We also demonstrate that the effects of individual structural features are additive and that redox potential tuning of azurin is now predictable across the full range of cupredoxin potentials.
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95
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Su P, Li H. Protonation of Type-1 Cu Bound Histidines: A Quantum Chemical Study. Inorg Chem 2009; 49:435-44. [DOI: 10.1021/ic9012735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Peifeng Su
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Hui Li
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
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96
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Crowley P, Matias P, Khan A, Roessle M, Svergun D. Metal-Mediated Self-Assembly of a β-Sandwich Protein. Chemistry 2009; 15:12672-80. [DOI: 10.1002/chem.200901410] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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97
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Affiliation(s)
- Amie K. Boal
- Departments of Biochemistry, Molecular Biology and Cell Biology and of Chemistry, Northwestern University, Evanston, IL 60208
| | - Amy C. Rosenzweig
- Departments of Biochemistry, Molecular Biology and Cell Biology and of Chemistry, Northwestern University, Evanston, IL 60208
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98
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Rajasekaran MB, Nilapwar S, Andrews SC, Watson KA. EfeO-cupredoxins: major new members of the cupredoxin superfamily with roles in bacterial iron transport. Biometals 2009; 23:1-17. [PMID: 19701722 DOI: 10.1007/s10534-009-9262-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Accepted: 08/10/2009] [Indexed: 12/31/2022]
Abstract
The EfeUOB system of Escherichia coli is a tripartite, low pH, ferrous iron transporter. It resembles the high-affinity iron transporter (Ftr1p-Fet3p) of yeast in that EfeU is homologous to Ftr1p, an integral-membrane iron-permease. However, EfeUOB lacks an equivalent of the Fet3p component--the multicopper oxidase with three cupredoxin-like domains. EfeO and EfeB are periplasmic but their precise roles are unclear. EfeO consists primarily of a C-terminal peptidase-M75 domain with a conserved 'HxxE' motif potentially involved in metal binding. The smaller N-terminal domain (EfeO-N) is predicted to be cupredoxin (Cup) like, suggesting a previously unrecognised similarity between EfeO and Fet3p. Our structural modelling of the E. coli EfeO Cup domain identifies two potential metal-binding sites. Site I is predicted to bind Cu(2+) using three conserved residues (C41 and 103, and E66) and M101. Of these, only one (C103) is conserved in classical cupredoxins where it also acts as a Cu ligand. Site II most probably binds Fe(3+) and consists of four well conserved surface Glu residues. Phylogenetic analysis indicates that the EfeO-Cup domains form a novel Cup family, designated the 'EfeO-Cup' family. Structural modelling of two other representative EfeO-Cup domains indicates that different subfamilies employ distinct ligand sets at their proposed metal-binding sites. The ~100 efeO homologues in the bacterial sequence databases are all associated with various iron-transport related genes indicating a common role for EfeO-Cup proteins in iron transport, supporting a new copper-iron connection in biology.
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Affiliation(s)
- Mohan B Rajasekaran
- School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, UK
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99
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Rajapandian V, Raman SS, Hakkim V, Parthasarathi R, Subramanian V. Molecular mechanics and molecular dynamics study on azurin using extensible and systematic force field (ESFF). ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.theochem.2009.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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100
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Rajapandian V, Hakkim V, Subramanian V. ONIOM Calculation on Azurin: Effect of Metal Ion Substitutions. J Phys Chem A 2009; 113:8615-25. [DOI: 10.1021/jp900451f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Rajapandian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Hakkim
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
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