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Yamaguchi T, Taborosi A, Sakai C, Akao K, Mori S, Kohzuma T. Systematic elucidation of the second coordination sphere effect on the structure and properties of a blue copper protein, pseudoazurin. J Inorg Biochem 2023; 246:112292. [PMID: 37354604 DOI: 10.1016/j.jinorgbio.2023.112292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/26/2023]
Abstract
The rational structural and computational studies of a blue copper protein, pseudoazurin (PAz), and its Met16X (X = Phe, Leu, Val, Ile) variants gave clear functional meanings of the noncovalent interaction (NCI) through the second coordination sphere. The high-resolution X-ray crystal structures of Met16X PAz demonstrated that the active site geometry is significantly affected by the substitution of Met16, which is located within the NCI distance from the His81 imidazole ring at the copper active site. The computational chemistry calculations based on the crystal structure analyses confirmed that the NCI of S-π/CH-π (wild-type), π-π (Met16Phe), double CH-π (Met16Leu), and single CH-π (Met16Val and Met16Ile). The estimated interaction energies for the NCI demonstrated that the fine-tuning of the protein stability and Cu site properties form the second coordination sphere of PAz.
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Affiliation(s)
- Takahide Yamaguchi
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan; Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1, Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Attila Taborosi
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan; Research Initiative for Supra-Materials, Faculty of Engineering, Shinshu University, 4-17-1, Wakasato, Nagano, Nagano 380-8553, Japan
| | - Chihiro Sakai
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Kohei Akao
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Seiji Mori
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan; Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1, Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Takamitsu Kohzuma
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan; Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1, Shirakata, Tokai, Ibaraki 319-1106, Japan.
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2
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Gammuto L, Chiellini C, Iozzo M, Fani R, Petroni G. The Azurin Coding Gene: Origin and Phylogenetic Distribution. Microorganisms 2021; 10:microorganisms10010009. [PMID: 35056457 PMCID: PMC8779525 DOI: 10.3390/microorganisms10010009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 12/31/2022] Open
Abstract
Azurin is a bacterial-derived cupredoxin, which is mainly involved in electron transport reactions. Interest in azurin protein has risen in recent years due to its anticancer activity and its possible applications in anticancer therapies. Nevertheless, the attention of the scientific community only focused on the azurin protein found in Pseudomonas aeruginosa (Proteobacteria, Gammaproteobacteria). In this work, we performed the first comprehensive screening of all the bacterial genomes available in online repositories to assess azurin distribution in the three domains of life. The Azurin coding gene was not detected in the domains Archaea and Eucarya, whereas it was detected in phyla other than Proteobacteria, such as Bacteroidetes, Verrucomicrobia and Chloroflexi, and a phylogenetic analysis of the retrieved sequences was performed. Observed patchy distribution and phylogenetic data suggest that once it appeared in the bacterial domain, the azurin coding gene was lost in several bacterial phyla and/or anciently horizontally transferred between different phyla, even though a vertical inheritance appeared to be the major force driving the transmission of this gene. Interestingly, a shared conserved domain has been found among azurin members of all the investigated phyla. This domain is already known in P. aeruginosa as p28 domain and its importance for azurin anticancer activity has been widely explored. These findings may open a new and intriguing perspective in deciphering the azurin anticancer mechanisms and to develop new tools for treating cancer diseases.
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Affiliation(s)
- Leandro Gammuto
- Department of Biology, University of Pisa, 56126 Pisa, Italy;
| | - Carolina Chiellini
- National Research Council, Institute of Agricultural Biology and Biotechnology, Via Moruzzi 1, 56124 Pisa, Italy;
| | - Marta Iozzo
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Viale Morgagni 50, 50134 Florence, Italy;
| | - Renato Fani
- Laboratory of Microbial and Molecular Evolution, Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
- Correspondence: (R.F.); (G.P.)
| | - Giulio Petroni
- Department of Biology, University of Pisa, 56126 Pisa, Italy;
- Correspondence: (R.F.); (G.P.)
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Yamaguchi T, Akatsu M, Taborosi A, Kohzuma T. Unusual Protein Stability of the Met16Leu Pseudoazurin Variant. CHEM LETT 2020. [DOI: 10.1246/cl.200578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Takahide Yamaguchi
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
- Frontier Research Center for Applied Atomic Sciences, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Miyu Akatsu
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Attila Taborosi
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Takamitsu Kohzuma
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
- Frontier Research Center for Applied Atomic Sciences, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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4
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Yamaguchi A, Edanami Y, Yamaguchi T, Shibuya Y, Fukaya N, Kohzuma T. Effect of Cavity Size of Mesoporous Silica on Type 1 Copper Site Geometry in Pseudoazurin. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20190355] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Akira Yamaguchi
- Institute of Quantum Beam Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
| | - Yurie Edanami
- Institute of Quantum Beam Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
| | - Takahide Yamaguchi
- Institute of Quantum Beam Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Yuuta Shibuya
- New Industry Creation Hatchery Center, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Norihisa Fukaya
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Takamitsu Kohzuma
- Institute of Quantum Beam Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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Kozak JJ, Gray HB, Garza-López RA. Relaxation of structural constraints during Amicyanin unfolding. J Inorg Biochem 2018; 179:135-145. [PMID: 29222970 PMCID: PMC7222854 DOI: 10.1016/j.jinorgbio.2017.11.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/28/2017] [Accepted: 11/17/2017] [Indexed: 11/21/2022]
Abstract
We study the thermal unfolding of amicyanin by quantifying the resiliency of the native state to structural perturbations. Three signatures characterizing stages of unfolding are identified. The first signature, lateral extension of the polypeptide chain, is calculated directly from the reported crystallographic data. Two other signatures, the radial displacement of each residue from Cu(II) and the angular spread in the chain as the protein unfolds, are calculated using crystallographic data in concert with a geometrical model we introduced previously (J.J. Kozak, H. B. Gray, R. A. Garza-López, J. Inorg. Biochem. 155(2016) 44-55). Particular attention is paid to the resiliency of the two beta sheets in amicyanin. The resiliency of residues in the near neighborhood of the Cu center to destabilization provides information on the persistence of the entatic state. Similarly, examining the resiliency of residues intercalated between structured regions (beta sheets, the alpha helix) provides a basis for identifying a "hydrophobic core." A principal focus of our study is to compare results obtained using our geometrical model with the experimental results (C. La Rosa, D. Milardi, D. M. Grasso, M. P. Verbeet, G. W. Canters, L. Sportelli, R. Guzzi, Eur. Biophy. J.30(8),(2002) 559-570) on the denaturation of amicyanin, and we show that our results support a classical model proposed by these authors.
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Affiliation(s)
- John J Kozak
- DePaul University, 243 South Wabash Ave., Chicago, IL 60604-6116, United States
| | - Harry B Gray
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, United States
| | - Roberto A Garza-López
- Department of Chemistry, Seaver Chemistry Laboratory, Pomona College, Claremont, CA 91711, United States.
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Periplasmic Nicotine Dehydrogenase NdhAB Utilizes Pseudoazurin as Its Physiological Electron Acceptor in Agrobacterium tumefaciens S33. Appl Environ Microbiol 2017. [PMID: 28625985 DOI: 10.1128/aem.01050-17] [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] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens S33 can grow with nicotine as the sole source of carbon, nitrogen, and energy via a novel hybrid of the pyridine pathway and the pyrrolidine pathway. Characterization of the enzymes involved in the hybrid pathway is important for understanding its biochemical mechanism. Here, we report that the molybdenum-containing nicotine dehydrogenase (NdhAB), which catalyzes the initial step of nicotine degradation, is located in the periplasm of strain S33, while the 6-hydroxynicotine oxidase and 6-hydroxypseudooxynicoine oxidase are in the cytoplasm. This is consistent with the fact that NdhA has a Tat signal peptide. Interestingly, an open reading frame (ORF) adjacent to the ndhAB gene was verified to encode a copper-containing electron carrier, pseudoazurin (Paz), which has a signal peptide typical of bacterial Paz proteins. Both were transported into the periplasm after being produced in the cytoplasm. We purified NdhAB from the periplasmic fraction of strain S33 and found that with Paz as the physiological electron acceptor, NdhAB catalyzed the hydroxylation of nicotine at a specific rate of 110.52 ± 8.09 μmol · min-1 · mg of protein-1, where the oxygen atom in the hydroxyl group of the product 6-hydroxynicotine was derived from H2O. The apparent Km values for nicotine and Paz were 1.64 ± 0.07 μM and 3.61 ± 0.23 μM, respectively. NAD(P)+, O2, and ferredoxin could not serve as electron acceptors. Disruption of the paz gene disabled the strain for nicotine degradation, indicating that Paz is required for nicotine catabolism in the strain. These findings help our understanding of electron transfer during nicotine degradation in bacteria.IMPORTANCE Nicotine is a toxic and addictive N-heterocyclic aromatic alkaloid produced in tobacco. Its catabolism in organisms and degradation in tobacco wastes have become major concerns for human health and the environment. Bacteria usually decompose nicotine using the classical strategy of hydroxylating the pyridine ring with the help of activated oxygen by nicotine dehydrogenase, which binds one molybdopterin, two [2Fe2S] clusters, and usually one flavin adenine dinucleotide (FAD) as well. However, the physiological electron acceptor for the reaction is still unknown. In this study, we found that the two-component nicotine dehydrogenase from Agrobacterium tumefaciens S33, naturally lacking an FAD-binding domain, is located in the periplasmic space and uses a copper-containing electron carrier, pseudoazurin, as its physiological electron acceptor. We report here the role of pseudoazurin in a reaction catalyzed by a molybdopterin-containing hydroxylase occurring in the periplasmic space. These results provide new biochemical knowledge on microbial degradation of N-heterocyclic aromatic compounds.
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Yamaguchi T, Nihei Y, Sutherland DEK, Stillman MJ, Kohzuma T. Stabilization of protein structure through π-π interaction in the second coordination sphere of pseudoazurin. Protein Sci 2017; 26:1921-1931. [PMID: 28691165 DOI: 10.1002/pro.3226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 07/01/2017] [Accepted: 07/04/2017] [Indexed: 11/11/2022]
Abstract
Noncovalent, weak interactions in the second coordination sphere of the copper active site of Pseudoazurin (PAz) from Achromobacter cycloclastes were examined using a series of Met16X variants. In this study, the differences in protein stability due to the changes in the nature of the 16th amino acid (Met, Phe, Val, Ile) were investigated by electrospray ionization mass spectrometry (ESI-MS) and far-UV circular dichroism (CD) as a result of acid denaturation. The percentage of native states (folded holo forms) of Met16Phe variants was estimated to be 75% at pH 2.9 although the wild-type (WT), Met16Val and Met16Ile PAz, became completely unfolded. The high stability under acidic conditions is correlated with the result of the active site being stabilized by the aromatic substitution of the Met16 residue. The π-π interaction in the second coordination sphere makes a significant contribution to the stability of active site and the protein matrix.
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Affiliation(s)
- Takahide Yamaguchi
- Graduate School of Science and Engineering, Institute of Quantum Beam Science, Ibaraki University, Mito, Ibaraki, 310-8512, Japan
| | - Yuko Nihei
- Graduate School of Science and Engineering, Institute of Quantum Beam Science, Ibaraki University, Mito, Ibaraki, 310-8512, Japan
| | - Duncan E K Sutherland
- Department of Biology, The University of Western Ontario, London, Ontario, Canada.,Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
| | - Martin J Stillman
- Department of Biology, The University of Western Ontario, London, Ontario, Canada.,Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
| | - Takamitsu Kohzuma
- Graduate School of Science and Engineering, Institute of Quantum Beam Science, Ibaraki University, Mito, Ibaraki, 310-8512, Japan
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Abstract
Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O2-reactive enzymes, raising the possibility that they play an antioxidant protective role. In blue copper proteins with plastocyanin-like domains, Tyr/Trp clusters are uncommon in the low-potential single-domain electron-transfer proteins and in the two-domain copper nitrite reductases. The two-domain muticopper oxidases, however, exhibit clusters of Tyr and Trp residues near the trinuclear copper active site where O2 is reduced. These clusters may play a protective role to ensure that reactive oxygen species are not liberated during O2 reduction.
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Affiliation(s)
- Harry B Gray
- Beckman Institute, California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125, USA
| | - Jay R Winkler
- Beckman Institute, California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125, USA
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9
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Yamaguchi T, Akao K, Takashina A, Asamura S, Unno M, Szilagyi RK, Kohzuma T. X-ray crystallographic evidence for the simultaneous presence of axial and rhombic sites in cupredoxins: atomic resolution X-ray crystal structure analysis of pseudoazurin and DFT modelling. RSC Adv 2016. [DOI: 10.1039/c6ra19282c] [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] Open
Abstract
The simultaneous presence of axial (blue) and rhombic (green) Cu sites in pseudoazurin is described from experiments and computational modelling.
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Affiliation(s)
- T. Yamaguchi
- Institute of Quantum Beam Science
- Ibaraki University
- Mito
- Japan
| | - K. Akao
- Institute of Quantum Beam Science
- Ibaraki University
- Mito
- Japan
| | - A. Takashina
- Institute of Quantum Beam Science
- Ibaraki University
- Mito
- Japan
| | - S. Asamura
- Institute of Quantum Beam Science
- Ibaraki University
- Mito
- Japan
| | - M. Unno
- Institute of Quantum Beam Science
- Ibaraki University
- Mito
- Japan
- Frontier Research Center for Applied Atomic Sciences
| | - R. K. Szilagyi
- Department of Chemistry and Biochemistry
- Montana State University
- Bozeman
- USA
- MTA-ELTE “Momentum” Chemical Structure/Function Laboratory
| | - T. Kohzuma
- Institute of Quantum Beam Science
- Ibaraki University
- Mito
- Japan
- Frontier Research Center for Applied Atomic Sciences
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Yamaguchi T, Yano J, Yachandra VK, Nihei Y, Togashi H, Szilagyi RK, Kohzuma T. The Allosteric Regulation of Axial/Rhombic Population in a “Type 1” Copper Site: Multi-Edge X-ray Absorption Spectroscopic and Density Functional Studies of Pseudoazurin. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2015. [DOI: 10.1246/bcsj.20150225] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | - Junko Yano
- Physical Biosciences Division, Lawrence Berkeley National Laboratory
| | | | - Yuko Nihei
- Institute of Applied Beam Science, Ibaraki University
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Gessmann R, Papadovasilaki M, Drougkas E, Petratos K. Zinc-substituted pseudoazurin solved by S/Zn-SAD phasing. Acta Crystallogr F Struct Biol Commun 2015; 71:19-23. [PMID: 25615962 PMCID: PMC4304741 DOI: 10.1107/s2053230x14025552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 11/22/2014] [Indexed: 11/10/2022] Open
Abstract
The copper(II) centre of the blue copper protein pseudoazurin from Alcaligenes faecalis has been substituted by zinc(II) via denaturing the protein, chelation and removal of copper and refolding the apoprotein, followed by the addition of an aqueous solution of ZnCl2. Vapour-diffusion experiments produced colourless hexagonal crystals (space group P65), which when cryocooled had unit-cell parameters a=b=49.01, c=98.08 Å. Diffraction data collected at 100 K using a copper sealed tube were phased by the weak anomalous signal of five S atoms and one Zn atom. The structure was fitted manually and refined to 1.6 Å resolution. The zinc-substituted protein exhibits similar overall geometry to the native structure with copper. Zn2+ binds more strongly to its four ligand atoms (His40 Nδ1, Cys78 Sγ, His81 Nδ1 and Met86 Sδ) and retains the tetrahedral arrangement, although the structure is less distorted than the native copper protein.
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Affiliation(s)
- Renate Gessmann
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), N. Plastira 100, 70 013 Heraklion, Greece
| | - Maria Papadovasilaki
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), N. Plastira 100, 70 013 Heraklion, Greece
| | - Evangelos Drougkas
- Department of Biology, University of Crete, PO Box 2208, 71 409 Heraklion, Greece
| | - Kyriacos Petratos
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), N. Plastira 100, 70 013 Heraklion, Greece
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Gast P, Broeren FG, Sottini S, Aoki R, Takashina A, Yamaguchi T, Kohzuma T, Groenen EJ. The type 1 copper site of pseudoazurin: Axial and rhombic. J Inorg Biochem 2014; 137:57-63. [DOI: 10.1016/j.jinorgbio.2014.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 03/25/2014] [Accepted: 03/28/2014] [Indexed: 11/29/2022]
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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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Laming EM, McGrath AP, Guss JM, Kappler U, Maher MJ. The X-ray crystal structure of a pseudoazurin from Sinorhizobium meliloti. J Inorg Biochem 2012; 115:148-54. [DOI: 10.1016/j.jinorgbio.2012.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/20/2012] [Accepted: 04/20/2012] [Indexed: 10/28/2022]
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15
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Cambria MT, Gullotto D, Garavaglia S, Cambria A. In silico study of structural determinants modulating the redox potential ofRigidoporus lignosusand other fungal laccases. J Biomol Struct Dyn 2012; 30:89-101. [DOI: 10.1080/07391102.2012.674275] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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16
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Hadt RG, Xie X, Pauleta SR, Moura I, Solomon EI. Analysis of resonance Raman data on the blue copper site in pseudoazurin: excited state π and σ charge transfer distortions and their relation to ground state reorganization energy. J Inorg Biochem 2012; 115:155-62. [PMID: 22560510 DOI: 10.1016/j.jinorgbio.2012.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 03/18/2012] [Accepted: 03/21/2012] [Indexed: 10/28/2022]
Abstract
The short Cu(2+)-S(Met) bond in pseudoazurin (PAz) results in the presence of two relatively intense S(p)(π) and S(p)(σ) charge transfer (CT) transitions. This has enabled resonance Raman (rR) data to be obtained for each excited state. The rR data show very different intensity distribution patterns for the vibrations in the 300-500 cm(-1) region. Time-dependent density functional theory (TDDFT) calculations have been used to determine that the change in intensity distribution between the S(p)(π) and S(p)(σ) excited states reflects the differential enhancement of S(Cys) backbone modes with Cu-S(Cys)-C(β) out-of-plane (oop) and in-plane (ip) bend character in their respective potential energy distributions (PEDs). The rR excited state distortions have been related to ground state reorganization energies (λ s) and predict that, in addition to M-L stretches, the Cu-S(Cys)-C(β) oop bend needs to be considered. DFT calculations predict a large distortion in the Cu-S(Cys)-C(β) oop bending coordinate upon reduction of a blue copper (BC) site; however, this distortion is not present in the X-ray crystal structures of reduced BC sites. The lack of Cu-S(Cys)-C(β) oop distortion upon reduction corresponds to a previously unconsidered constraint on the thiolate ligand orientation in the reduced state of BC proteins and can be considered as a contribution to the entatic/rack nature of BC sites.
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Affiliation(s)
- Ryan G Hadt
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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Dell'acqua S, Moura I, Moura JJG, Pauleta SR. The electron transfer complex between nitrous oxide reductase and its electron donors. J Biol Inorg Chem 2011; 16:1241-54. [PMID: 21739254 DOI: 10.1007/s00775-011-0812-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 06/20/2011] [Indexed: 11/25/2022]
Abstract
Identifying redox partners and the interaction surfaces is crucial for fully understanding electron flow in a respiratory chain. In this study, we focused on the interaction of nitrous oxide reductase (N(2)OR), which catalyzes the final step in bacterial denitrification, with its physiological electron donor, either a c-type cytochrome or a type 1 copper protein. The comparison between the interaction of N(2)OR from three different microorganisms, Pseudomonas nautica, Paracoccus denitrificans, and Achromobacter cycloclastes, with their physiological electron donors was performed through the analysis of the primary sequence alignment, electrostatic surface, and molecular docking simulations, using the bimolecular complex generation with global evaluation and ranking algorithm. The docking results were analyzed taking into account the experimental data, since the interaction is suggested to have either a hydrophobic nature, in the case of P. nautica N(2)OR, or an electrostatic nature, in the case of P. denitrificans N(2)OR and A. cycloclastes N(2)OR. A set of well-conserved residues on the N(2)OR surface were identified as being part of the electron transfer pathway from the redox partner to N(2)OR (Ala495, Asp519, Val524, His566 and Leu568 numbered according to the P. nautica N(2)OR sequence). Moreover, we built a model for Wolinella succinogenes N(2)OR, an enzyme that has an additional c-type-heme-containing domain. The structures of the N(2)OR domain and the c-type-heme-containing domain were modeled and the full-length structure was obtained by molecular docking simulation of these two domains. The orientation of the c-type-heme-containing domain relative to the N(2)OR domain is similar to that found in the other electron transfer complexes.
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Affiliation(s)
- Simone Dell'acqua
- REQUIMTE/CQFB, Departamento de Química, Universidade Nova de Lisboa, Caparica, Portugal
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18
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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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Gessmann R, Kyvelidou C, Papadovasilaki M, Petratos K. The crystal structure of cobalt-substituted pseudoazurin from Alcaligenes faecalis. Biopolymers 2010; 95:202-7. [DOI: 10.1002/bip.21553] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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20
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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: 170] [Impact Index Per Article: 12.1] [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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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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22
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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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23
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Hira D, Nojiri M, Suzuki S. Crystallization and preliminary X-ray diffraction analysis of a complex between the electron-transfer partners hexameric Cu-containing nitrite reductase and pseudoazurin. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:116-9. [PMID: 19193999 DOI: 10.1107/s1744309108040219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 11/29/2008] [Indexed: 11/10/2022]
Abstract
The complex between Cu-containing nitrite reductase (HdNIR) and its electron-donor protein pseudoazurin (HdPAz) from Hyphomicrobium denitrificans has been crystallized. The crystals were obtained from a mixture of the two proteins using the hanging-drop vapour-diffusion method in the presence of polyethylene glycol (PEG) and 2-methyl-2,4-pentanediol (MPD) as precipitants. SDS-PAGE analysis demonstrated that the crystals contained both proteins. The X-ray diffraction experiment was carried out at SPring-8 and diffraction data were collected to 3.3 A resolution. The crystals were tetragonal (space group P4(1)2(1)2), with unit-cell parameters a = b = 130.39, c = 505.55 A. Preliminary analysis indicated that there was one HdNIR and at least two HdPAz molecules in the asymmetric unit of the crystal.
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Affiliation(s)
- Daisuke Hira
- Bioinorganic Chemistry Laboratory, Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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24
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Yanagisawa S, Crowley PB, Firbank SJ, Lawler AT, Hunter DM, McFarlane W, Li C, Kohzuma T, Banfield MJ, Dennison C. π-Interaction Tuning of the Active Site Properties of Metalloproteins. J Am Chem Soc 2008; 130:15420-8. [DOI: 10.1021/ja8038135] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Sachiko Yanagisawa
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Peter B. Crowley
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Susan J. Firbank
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Anne T. Lawler
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - David M. Hunter
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - William McFarlane
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Chan Li
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Takamitsu Kohzuma
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Mark J. Banfield
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
| | - Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K., UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, School of Natural Sciences (Chemistry), Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., and Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
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25
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Zhang Y, Oldfield E. NMR hyperfine shifts in blue copper proteins: a quantum chemical investigation. J Am Chem Soc 2008; 130:3814-23. [PMID: 18314973 DOI: 10.1021/ja075978b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present the results of the first quantum chemical investigations of 1H NMR hyperfine shifts in the blue copper proteins (BCPs): amicyanin, azurin, pseudoazurin, plastocyanin, stellacyanin, and rusticyanin. We find that very large structural models that incorporate extensive hydrogen bond networks, as well as geometry optimization, are required to reproduce the experimental NMR hyperfine shift results, the best theory vs experiment predictions having R2 = 0.94, a slope = 1.01, and a SD = 40.5 ppm (or approximately 4.7% of the overall approximately 860 ppm shift range). We also find interesting correlations between the hyperfine shifts and the bond and ring critical point properties computed using atoms-in-molecules theory, in addition to finding that hyperfine shifts can be well-predicted by using an empirical model, based on the geometry-optimized structures, which in the future should be of use in structure refinement.
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Affiliation(s)
- Yong Zhang
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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26
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Abstract
Many approaches are being used to engineer metalloproteins, with most of these informed by, and aiming to further elucidate, the basic structural requirements for biological metal centers. Cupredoxins are type 1 (T1) copper-containing electron transfer (ET) proteins with a -barrel fold that is thought to constrain metal site structure. The T1 copper ion is bound by ligands mainly originating from a single active site loop whose length and structure varies. This Highlight article will focus on protein engineering studies which have investigated the role of the metal-binding loop for active site integrity and functionality. Scaffold differences are present within the cupredoxin family and their influence has also been assessed. Given the widespread occurrence of -barrel domains in nature, and the array of metal sites in proteins composed of loop regions, the studies described on this model system have implications for a variety of metalloproteins.
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Affiliation(s)
- Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, UK.
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27
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Abdelhamid RF, Obara Y, Kohzuma T. Alkaline transition of pseudoazurin Met16X mutant proteins: protein stability influenced by the substitution of Met16 in the second sphere coordination. J Inorg Biochem 2008; 102:1373-9. [PMID: 18343503 DOI: 10.1016/j.jinorgbio.2008.01.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 01/08/2008] [Accepted: 01/16/2008] [Indexed: 10/22/2022]
Abstract
Several blue copper proteins are known to change the active site structure at alkaline pH (alkaline transition). Spectroscopic studies of Met16Phe, Met16Tyr, Met16Trp, and Met16Val pseudoazurin variants were performed to investigate the second sphere role through alkaline transition. The visible electronic absorption and resonance Raman spectra of Met16Phe, Met16Tyr, and Met16Trp variants showed the increasing of axial component at pH approximately 11 like wild-type PAz. The visible electronic absorption and far-UV CD spectra of Met16Val demonstrated that the destabilization of the protein structure was triggered at pH>11. Resonance Raman (RR) spectra of PAz showed that the intensity-weighted averaged Cu-S(Cys) stretching frequency was shifted to higher frequency region at pH approximately 11. The higher frequency shift of Cu-S(Cys) bond is implied the stronger Cu-S(Cys) bond at alkaline transition pH approximately 11. The visible electronic absorption and far-UV CD spectra of Met16X PAz revealed that the Met16Val variant is denatured at pH>11, but Met16Phe, Met16Tyr, and Met16Trp mutant proteins are not denatured even at pH>11. These observations suggest that Met16 is important to maintain the protein structure through the possible weak interaction between methionine -SCH3 part and coordinated histidine imidazole moiety. The introduction of pi-pi interaction in the second coordination sphere may be contributed to the enhancement of protein structure stability.
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Affiliation(s)
- Rehab F Abdelhamid
- Institute of Applied Beam Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan
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28
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Abstract
Copper-containing nitrite reductases (NiRs) possess type 1 (T1) and type 2 (T2) copper sites and can be either green or blue in color owing to differences at their T1 centers. The active sites of a green and a blue NiR were studied by utilizing their T1CuI/T2CoII and T1CoII/T2CoII-substituted forms. The UV/Vis spectra of these derivatives highlight the similarity of the T2 centers in these enzymes and that T1 site differences are also present in the CoII forms. The paramagnetic NMR spectra of T1CuI/T2CoII enzymes allow hyperfine shifted resonances from the three T2 His ligands to be assigned: these exhibit remarkably similar positions in the spectra of both NiRs, emphasizing the homology of the T2 centers. The addition of nitrite results in subtle alterations in the paramagnetic NMR spectra of the T1CuI/T2CoII forms at pH<7, which indicate a geometry change upon the binding of substrate. Shifted resonances from all of the T1 site ligands have been assigned and the CoII--N(His) interactions are alike, whereas the CbetaH proton resonances of the Cys ligand exhibit subtle chemical shift differences in the blue and green NiRs. The strength of the axial CoII--S(Met) interaction is similar in the two NiRs studied, but the altered conformation of the side chain of this ligand results in a dramatically different chemical shift pattern for the CgammaH protons. This indicates an alteration in the bonding of the axial ligand in these derivatives, which could be influential in the CuII proteins.
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Affiliation(s)
- Katsuko Sato
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, UK
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29
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Abdelhamid RF, Obara Y, Uchida Y, Kohzuma T, Dooley DM, Brown DE, Hori H. π–π interaction between aromatic ring and copper-coordinated His81 imidazole regulates the blue copper active-site structure. J Biol Inorg Chem 2006; 12:165-73. [PMID: 17031705 DOI: 10.1007/s00775-006-0176-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 09/07/2006] [Indexed: 10/24/2022]
Abstract
Noncovalent weak interactions play important roles in biological systems. In particular, such interactions in the second coordination shell of metal ions in proteins may modulate the structure and reactivity of the metal ion site in functionally significant ways. Recently, pi-pi interactions between metal ion coordinated histidine imidazoles and aromatic amino acids have been recognized as potentially important contributors to the properties of metal ion sites. In this paper we demonstrate that in pseudoazurin (a blue copper protein) the pi-pi interaction between a coordinated histidine imidazole ring and the side chains of aromatic amino acids in the second coordination sphere, significantly influences the properties of the blue copper site. Electronic absorption and electron paramagnetic resonance spectra indicate that the blue copper electronic structure is perturbed, as is the redox potential, by the introduction of a second coordination shell pi-pi interaction. We suggest that the pi-pi interaction with the metal ion coordinated histidine imidazole ring modulates the electron delocalization in the active site, and that such interactions may be functionally important in refining the reactivity of blue copper sites.
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Affiliation(s)
- Rehab F Abdelhamid
- Institute of Applied Beam Science, Ibaraki University, Mito, Ibaraki, 310-8512, Japan
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31
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Dennison C. Ligand and loop variations at type 1 copper sites: influence on structure and reactivity. Dalton Trans 2005:3436-42. [PMID: 16234922 DOI: 10.1039/b507440c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Type 1 (T1) copper sites promote biological electron transfer and are found in the cupredoxins and a number of copper-containing enzymes including the multi-copper oxidases. A T1 copper site usually has a distorted tetrahedral geometry with strong ligands provided by the thiolate sulfur of a Cys and the imidazole nitrogens of two His residues. The active site structure is typically completed by a weak axial Met ligand (a second weak axial interaction is found in azurin resulting in a trigonal bipyramidal geometry). The axial Met is not conserved and Gln, Phe, Leu and Val are also found in this position. Three of the four ligands at a T1 copper site are situated on a single C-terminal loop whose length and structure varies. Studies are discussed which investigate both the influence of physiologically relevant axial ligand alterations, and also of mutations to the length and structure of the ligand-containing loop, on the properties of T1 copper sites.
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Affiliation(s)
- Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, UK NE2 4HH.
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32
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Pinho D, Besson S, Brondino CD, Pereira E, de Castro B, Moura I. Two azurins with unusual redox and spectroscopic properties isolated from the Pseudomonas chlororaphis strains DSM 50083T and DSM 50135. J Inorg Biochem 2004; 98:276-86. [PMID: 14729308 DOI: 10.1016/j.jinorgbio.2003.10.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Two azurins (Az624 and Az626) were isolated from the soluble extract of two strains of Pseudomonas chlororaphis, DSM 50083(T) and DSM 50135, respectively, grown under microaerobic conditions with nitrate as final electron acceptor. The azurins, purified to electrophoretic homogeneity in three chromatographic steps, exhibit several peculiar properties. They have high reduction potentials and lower pI than most azurins described in the literature. As previously observed for Pseudomonas aeruginosa azurin, their reduction potentials are pH-dependent, but the pK values of their oxidized forms are lower, which suggests that deeper structural changes are associated with the oxidation process of these novel azurins. A hitherto undescribed pH-dependence of the diffusion coefficient was observed in Az624, that could be caused either by conformational changes, or by the formation of supramolecular aggregates associated with a protonation process. Both azurins exhibit axial X-band electron paramagnetic resonance spectra in frozen solution showing a typical hyperfine with the copper nucleus (I=3/2) and a well-resolved superhyperfine structure with two equivalent 14N nucleus (I=1), which is not usually observed for azurins from other species.
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Affiliation(s)
- Dora Pinho
- REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Porto 4169-007, Portugal
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33
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UV resonance Raman and NMR spectroscopic studies on the pH dependent metal ion release from pseudoazurin. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00937-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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34
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Jain R, Shapleigh JP. Characterization of nirV and a gene encoding a novel pseudoazurin in Rhodobacter sphaeroides 2.4.3. MICROBIOLOGY (READING, ENGLAND) 2001; 147:2505-2515. [PMID: 11535790 DOI: 10.1099/00221287-147-9-2505] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sequencing of the region flanking nirK, the gene encoding the copper-containing nitrite reductase in Rhodobacter sphaeroides 2.4.3, has identified two genes whose products could potentially be involved in nitrite reductase expression and activity. One of the genes has been designated nirV. Putative nirV orthologues are found in other denitrifiers, where they are also located downstream of the structural gene for nitrite reductase. The nirV in 2.4.3 is apparently cotranscribed with nirK. Inactivation of nirV had no effect on cell growth, or on nitrite reductase expression or activity. Downstream of nirV and divergently transcribed is a gene, designated ppaZ, encoding a protein with significant similarity to pseudoazurins from other denitrifiers. However, three of the four residues required for binding of the type I copper centre are not conserved in the deduced sequence of the protein in 2.4.3. ppaZ is expressed only when oxygen becomes limiting. ppaZ expression is dependent on both FnrL and NnrR, and a putative binding site for these proteins has been identified. Expression of ppaZ is also dependent on the two-component PrrB/PrrA system. Inactivation of ppaZ had no significant effect on cell growth or on nitrite reductase expression or activity. Expression of a maltose-binding protein-PpaZ fusion indicated that the protein could not bind copper. Examination of the genome of the related bacterium R. sphaeroides 2.4.1 revealed that it encodes ppaZ but not nirV and evidence is presented suggesting that a common ancestor of 2.4.3 and 2.4.1 had both nitrite and nitric oxide reductase activity but as the strains diverged 2.4.1 lost nirK and nirV, making it incapable of nitrite reduction.
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Affiliation(s)
- Roshan Jain
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, NY 14853-8101, USA1
| | - James P Shapleigh
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, NY 14853-8101, USA1
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35
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Metzler DE, Metzler CM, Sauke DJ. Transition Metals in Catalysis and Electron Transport. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50019-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Metzler DE, Metzler CM, Sauke DJ. Electron Transport, Oxidative Phosphorylation, and Hydroxylation. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50021-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kataoka K, Kondo A, Yamaguchi K, Suzuki S. Spectroscopic and electrochemical properties of the Met86Gln mutant of Achromobacter cycloclastes pseudoazurin. J Inorg Biochem 2000; 82:79-84. [PMID: 11132642 DOI: 10.1016/s0162-0134(00)00146-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mutant replacing the Met86 ligand of Achromobacter cycloclastes pseudoazurin (Ac-pAz) with Gln has been prepared and spectroscopically and electrochemically characterized. Ac-pAz has four ligands (2His, Cys, and Met) and donates one electron to its cognate Cu-containing nitrite reductase (Ac-NIR). The mutant ([Met86Gln]pAz) shows the electronic absorption and CD spectra considerably similar to those of zucchini mavicyanin (Mv) and lacquer and cucumber stellacyanins (St) having 2His, Cys, and Gln. The EPR signal of the mutant has an axial character, although those of Mv and St show rhombic signals. The findings indicate that the Cu site having Gln might be a distorted trigonal geometry. The half-wave potentials (E(1/2)) of [Met86Gln]pAz and the intermolecular electron-transfer rate constant (kET) from the mutant to Ac-NIR were determined by cyclic voltammetry at pH 7.0 and 25 degrees C. The E(1/2) is +134 mV (versus NHE) and the coordination of Gln instead of Met negatively shifts the E(1/2) of Ac-pAz (+260 mV (versus NHE)). The kET of [Met86Gln]pAz (1.2x10(6) M(-1) s(-1)) is larger than that of the recombinant Ac-pAz (7.5x10(5) M(-1) s(-1)).
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Affiliation(s)
- K Kataoka
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Japan
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Thompson GS, Leung YC, Ferguson SJ, Radford SE, Redfield C. The structure and dynamics in solution of Cu(I) pseudoazurin from Paracoccus pantotrophus. Protein Sci 2000; 9:846-58. [PMID: 10850794 PMCID: PMC2144627 DOI: 10.1110/ps.9.5.846] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The solution structure and backbone dynamics of Cu(I) pseudoazurin, a 123 amino acid electron transfer protein from Paracoccus pantotrophus, have been determined using NMR methods. The structure was calculated to high precision, with a backbone RMS deviation for secondary structure elements of 0.35+/-0.06 A, using 1,498 distance and 55 torsion angle constraints. The protein has a double-wound Greek-key fold with two alpha-helices toward its C-terminus, similar to that of its oxidized counterpart determined by X-ray crystallography. Comparison of the Cu(I) solution structure with the X-ray structure of the Cu(II) protein shows only small differences in the positions of some of the secondary structure elements. Order parameters S2, measured for amide nitrogens, indicate that the backbone of the protein is rigid on the picosecond to nanosecond timescale.
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Affiliation(s)
- G S Thompson
- School of Biochemistry and Molecular Biology, University of Leeds, United Kingdom
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