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Edvardsen PKT, Askarian F, Zurich R, Nizet V, Vaaje-Kolstad G. Exploring roles of the chitinase ChiC in modulating Pseudomonas aeruginosa virulence phenotypes. Microbiol Spectr 2024; 12:e0054624. [PMID: 38819151 PMCID: PMC11218509 DOI: 10.1128/spectrum.00546-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 04/23/2024] [Indexed: 06/01/2024] Open
Abstract
Chitinases are ubiquitous enzymes involved in biomass degradation and chitin turnover in nature. Pseudomonas aeruginosa (PA), an opportunistic human pathogen, expresses ChiC, a secreted glycoside hydrolase 18 family chitinase. Despite speculation about ChiC's role in PA disease pathogenesis, there is scant evidence supporting this hypothesis. Since PA cannot catabolize chitin, we investigated the potential function(s) of ChiC in PA pathophysiology. Our findings show that ChiC exhibits activity against both insoluble (α- and β-chitin) and soluble chitooligosaccharides. Enzyme kinetics toward (GlcNAc)4 revealed a kcat of 6.50 s-1 and a KM of 1.38 mM, the latter remarkably high for a canonical chitinase. In our label-free proteomics investigation, ChiC was among the most abundant proteins in the Pel biofilm, suggesting a potential contribution to PA biofilm formation. Using an intratracheal challenge model of PA pneumonia, the chiC::ISphoA/hah transposon insertion mutant paradoxically showed slightly increased virulence compared to the wild-type parent strain. Our results indicate that ChiC is a genuine chitinase that contributes to a PA pathoadaptive pathway.IMPORTANCEIn addition to performing chitin degradation, chitinases from the glycoside hydrolase 18 family have been found to play important roles during pathogenic bacterial infection. Pseudomonas aeruginosa is an opportunistic pathogen capable of causing pneumonia in immunocompromised individuals. Despite not being able to grow on chitin, the bacterium produces a chitinase (ChiC) with hitherto unknown function. This study describes an in-depth characterization of ChiC, focusing on its potential contribution to the bacterium's disease-causing ability. We demonstrate that ChiC can degrade both polymeric chitin and chitooligosaccharides, and proteomic analysis of Pseudomonas aeruginosa biofilm revealed an abundance of ChiC, hinting at a potential role in biofilm formation. Surprisingly, a mutant strain incapable of ChiC production showed higher virulence than the wild-type strain. While ChiC appears to be a genuine chitinase, further investigation is required to fully elucidate its contribution to Pseudomonas aeruginosa virulence, an important task given the evident health risk posed by this bacterium.
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Affiliation(s)
| | - Fatemeh Askarian
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California, USA
| | - Raymond Zurich
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California, USA
| | - Victor Nizet
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, California, USA
| | - Gustav Vaaje-Kolstad
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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2
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Wilson LA, Melville JN, Pedroso MM, Krco S, Hoelzle R, Zaugg J, Southam G, Virdis B, Evans P, Supper J, Harmer JR, Tyson G, Clark A, Schenk G, Bernhardt PV. Kinetic, electrochemical and spectral characterization of bacterial and archaeal rusticyanins; unexpected stability issues and consequences for applications in biotechnology. J Inorg Biochem 2024; 256:112539. [PMID: 38593609 DOI: 10.1016/j.jinorgbio.2024.112539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/11/2024]
Abstract
Motivated by the ambition to establish an enzyme-driven bioleaching pathway for copper extraction, properties of the Type-1 copper protein rusticyanin from Acidithiobacillus ferrooxidans (AfR) were compared with those from an ancestral form of this enzyme (N0) and an archaeal enzyme identified in Ferroplasma acidiphilum (FaR). While both N0 and FaR show redox potentials similar to that of AfR their electron transport rates were significantly slower. The lack of a correlation between the redox potentials and electron transfer rates indicates that AfR and its associated electron transfer chain evolved to specifically facilitate the efficient conversion of the energy of iron oxidation to ATP formation. In F. acidiphilum this pathway is not as efficient unless it is up-regulated by an as of yet unknown mechanism. In addition, while the electrochemical properties of AfR were consistent with previous data, previously unreported behavior was found leading to a form that is associated with a partially unfolded form of the protein. The cyclic voltammetry (CV) response of AfR immobilized onto an electrode showed limited stability, which may be connected to the presence of the partially unfolded state of this protein. Insights gained in this study may thus inform the engineering of optimized rusticyanin variants for bioleaching processes as well as enzyme-catalyzed solubilization of copper-containing ores such as chalcopyrite.
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Affiliation(s)
- Liam A Wilson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jamie N Melville
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Marcelo M Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Stefan Krco
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert Hoelzle
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Julian Zaugg
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Gordon Southam
- School of the Environment, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Bernardino Virdis
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul Evans
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jenna Supper
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jeffrey R Harmer
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Gene Tyson
- Centre for Microbiome Research, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Alice Clark
- Sustainable Minerals Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia; Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia; Sustainable Minerals Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.
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3
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Gibbs CA, Ghazi N, Tao J, Warren JJ. An Investigation of the Influence of Tyrosine Local Interactions on Electron Hopping in a Model Protein. Molecules 2024; 29:350. [PMID: 38257263 PMCID: PMC10818705 DOI: 10.3390/molecules29020350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
Multi-step electron transfer reactions are important to the function of many cellular systems. The ways in which such systems have evolved to direct electrons along specific pathways are largely understood, but less so are the ways in which the reduction-oxidation potentials of individual redox sites are controlled. We prepared a series of three new artificial variants of Pseudomonas aeruginosa azurin where a tyrosine (Tyr109) is situated between the native Cu ion and a Ru(II) photosensitizer tethered to a histidine (His107). Arginine, glutamine, or methionine were introduced as position 122, which is near to Tyr109. We investigated the rate of CuI oxidation by a flash-quench generated Ru(III) oxidant over pH values from 5 to 9. While the identity of the residue at position 122 affects some of the physical properties of Tyr109, the rates of CuI oxidation are only weakly dependent on the identity of the residue at 122. The results highlight that more work is still needed to understand how non-covalent interactions of redox active groups are affected in redox proteins.
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Affiliation(s)
| | | | | | - Jeffrey J. Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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4
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Luo J, He C. Chemical protein synthesis enabled engineering of saccharide oxidative cleavage activity in artificial metalloenzymes. Int J Biol Macromol 2024; 256:128083. [PMID: 38000595 DOI: 10.1016/j.ijbiomac.2023.128083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/18/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023]
Abstract
Chemical protein (semi-)synthesis is a powerful technique allowing the incorporation of unnatural functionalities at any desired protein site. Herein we describe a facile one-pot semi-synthetic strategy for the construction of a type 2 copper center in the active site of azurin, which is achieved by substitution of Met121 with unnatural amino acid residues bearing a strong ligand N,N-bis(pyridylmethyl)amine (DPA) to mimic the function of typical histidine brace-bearing copper monooxygenases, such as lytic polysaccharide monooxygenases (LPMOs) involved in polysaccharide breakdown. The semi-synthetic proteins were routinely obtained in over 10-mg scales to allow for spectroscopic measurements (UV-Vis, CD, and EPR), which provides structural evidences for the CuII-DPA-modified azurins. 4-nitrophenyl-β-D-glucopyranoside (PNPG) was used as a model substrate for the H2O2-driven oxidative cleavage reaction facilitated by semi-synthetic azurins, and the CuII-6 complex showed a highest activity (TTN 253). Interestingly, our semi-synthetic azurins were able to tolerate high H2O2 concentrations (up to 4000-fold of the enzyme), making them promising for practical applications. Collectively, we establish that chemical protein synthesis can be exploited as a reliable technology in affording large quantities of artificial metalloproteins to facilitate the transformation of challenging chemical reactions.
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Affiliation(s)
- Jindi Luo
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Chunmao He
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, PR China.
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5
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Mammoser CC, LeMasters BE, Edwards SG, McRae EM, Mullins MH, Wang Y, Garcia NM, Edmonds KA, Giedroc DP, Thielges MC. The structure of plastocyanin tunes the midpoint potential by restricting axial ligation of the reduced copper ion. Commun Chem 2023; 6:175. [PMID: 37612467 PMCID: PMC10447441 DOI: 10.1038/s42004-023-00977-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 08/07/2023] [Indexed: 08/25/2023] Open
Abstract
Blue copper proteins are models for illustrating how proteins tune metal properties. Nevertheless, the mechanisms by which the protein controls the metal site remain to be fully elucidated. A hindrance is that the closed shell Cu(I) site is inaccessible to most spectroscopic analyses. Carbon deuterium (C-D) bonds used as vibrational probes afford nonperturbative, selective characterization of the key cysteine and methionine copper ligands in both redox states. The structural integrity of Nostoc plastocyanin was perturbed by disrupting potential hydrogen bonds between loops of the cupredoxin fold via mutagenesis (S9A, N33A, N34A), variably raising the midpoint potential. The C-D vibrations show little change to suggest substantial alteration to the Cu(II) coordination in the oxidized state or in the Cu(I) interaction with the cysteine ligand. They rather indicate, along with visible and NMR spectroscopy, that the methionine ligand distinctly interacts more strongly with the Cu(I) ion, in line with the increases in midpoint potential. Here we show that the protein structure determines the redox properties by restricting the interaction between the methionine ligand and Cu(I) in the reduced state.
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Affiliation(s)
- Claire C Mammoser
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Brynn E LeMasters
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
- Department of Chemistry, University of Wisconsin, Madison, WI, 53706, USA
| | - Sydney G Edwards
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Emma M McRae
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - M Hunter Mullins
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
- Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Yiqi Wang
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Nicholas M Garcia
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
- University of Wisconsin School of Medicine and Public Health, Madison, WI, 53726, USA
| | - Katherine A Edmonds
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - David P Giedroc
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Megan C Thielges
- Indiana University Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA.
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6
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Singha A, Sekretareva A, Tao L, Lim H, Ha Y, Braun A, Jones SM, Hedman B, Hodgson KO, Britt RD, Kosman DJ, Solomon EI. Tuning the Type 1 Reduction Potential of Multicopper Oxidases: Uncoupling the Effects of Electrostatics and H-Bonding to Histidine Ligands. J Am Chem Soc 2023. [PMID: 37294874 PMCID: PMC10392966 DOI: 10.1021/jacs.3c03241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In multicopper oxidases (MCOs), the type 1 (T1) Cu accepts electrons from the substrate and transfers these to the trinuclear Cu cluster (TNC) where O2 is reduced to H2O. The T1 potential in MCOs varies from 340 to 780 mV, a range not explained by the existing literature. This study focused on the ∼350 mV difference in potential of the T1 center in Fet3p and Trametes versicolor laccase (TvL) that have the same 2His1Cys ligand set. A range of spectroscopies performed on the oxidized and reduced T1 sites in these MCOs shows that they have equivalent geometric and electronic structures. However, the two His ligands of the T1 Cu in Fet3p are H-bonded to carboxylate residues, while in TvL they are H-bonded to noncharged groups. Electron spin echo envelope modulation spectroscopy shows that there are significant differences in the second-sphere H-bonding interactions in the two T1 centers. Redox titrations on type 2-depleted derivatives of Fet3p and its D409A and E185A variants reveal that the two carboxylates (D409 and E185) lower the T1 potential by 110 and 255-285 mV, respectively. Density functional theory calculations uncouple the effects of the charge of the carboxylates and their difference in H-bonding interactions with the His ligands on the T1 potential, indicating 90-150 mV for anionic charge and ∼100 mV for a strong H-bond. Finally, this study provides an explanation for the generally low potentials of metallooxidases relative to the wide range of potentials of the organic oxidases in terms of different oxidized states of their TNCs involved in catalytic turnover.
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Affiliation(s)
- Asmita Singha
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Alina Sekretareva
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Lizhi Tao
- Department of Chemistry, University of California at Davis, Davis, California 95616, United States
| | - Hyeongtaek Lim
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Yang Ha
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Augustin Braun
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Stephen M Jones
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Keith O Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - R David Britt
- Department of Chemistry, University of California at Davis, Davis, California 95616, United States
| | - Daniel J Kosman
- Department of Biochemistry, The University at Buffalo, Buffalo, New York 14214, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
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7
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Gibbs C, Fedoretz-Maxwell BP, MacNeil GA, Walsby CJ, Warren JJ. Proximal Methionine Amino Acid Residue Affects the Properties of Redox-Active Tryptophan in an Artificial Model Protein. ACS OMEGA 2023; 8:19798-19806. [PMID: 37305310 PMCID: PMC10249128 DOI: 10.1021/acsomega.3c01589] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/11/2023] [Indexed: 06/13/2023]
Abstract
Redox-active amino acid residues are at the heart of biological electron-transfer reactions. They play important roles in natural protein functions and are implicated in disease states (e.g., oxidative-stress-associated disorders). Tryptophan (Trp) is one such redox-active amino acid residue, and it has long been known to serve a functional role in proteins. Broadly speaking, there is still much to learn about the local features that make some Trp redox active and others inactive. Herein, we describe a new protein model system where we investigate how a methionine (Met) residue proximal to a redox-active Trp affects its reactivity and spectroscopy. We use an artificial variant of azurin from Pseudomonas aeruginosa to produce these models. We employ a series of UV-visible spectroscopy, electrochemistry, electron paramagnetic resonance, and density functional theory experiments to demonstrate the effect that placing Met near Trp radicals has in the context of redox proteins. The introduction of Met proximal to Trp lowers its reduction potential by ca. 30 mV and causes clear shifts in the optical spectra of the corresponding radicals. While the effect may be small, it is significant enough to be a way for natural systems to tune Trp reactivity.
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8
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Rivera JJ, Trinh C, Kim JE. Photoinduced Electron Transfer from the Tryptophan Triplet State in Zn-Azurin. ACS PHYSICAL CHEMISTRY AU 2022; 3:63-73. [PMID: 36718260 PMCID: PMC9881450 DOI: 10.1021/acsphyschemau.2c00042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/30/2022]
Abstract
Tryptophan is one of few residues that participates in biological electron transfer reactions. Upon substitution of the native Cu2+ center with Zn2+ in the blue-copper protein azurin, a long-lived tryptophan neutral radical can be photogenerated. We report the following quantum yield values for Zn-substituted azurin in the presence of the electron acceptor Cu(II)-azurin: formation of the tryptophan neutral radical (Φrad), electron transfer (ΦET), fluorescence (Φfluo), and phosphorescence (Φphos), as well as the efficiency of proton transfer of the cation radical (ΦPT). Increasing the concentration of the electron acceptor increased Φrad and ΦET values and decreased Φphos without affecting Φfluo. At all concentrations of the acceptor, the value of ΦPT was nearly unity. These observations indicate that the phosphorescent triplet state is the parent state of electron transfer and that nearly all electron transfer events lead to proton loss. Similar results regarding the parent state were obtained with a different electron acceptor, [Co(NH3)5Cl]2+; however, Stern-Volmer graphs revealed that [Co(NH3)5Cl]2+ was a more effective phosphorescence quencher (K SV = 230 000 M-1) compared to Cu(II)-azurin (K SV = 88 000 M-1). Competition experiments in the presence of both [Co(NH3)5Cl]2+ and Cu(II)-azurin suggested that [Co(NH3)5Cl]2+ is the preferred electron acceptor. Implications of these results in terms of quenching mechanisms are discussed.
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9
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Van Stappen C, Deng Y, Liu Y, Heidari H, Wang JX, Zhou Y, Ledray AP, Lu Y. Designing Artificial Metalloenzymes by Tuning of the Environment beyond the Primary Coordination Sphere. Chem Rev 2022; 122:11974-12045. [PMID: 35816578 DOI: 10.1021/acs.chemrev.2c00106] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metalloenzymes catalyze a variety of reactions using a limited number of natural amino acids and metallocofactors. Therefore, the environment beyond the primary coordination sphere must play an important role in both conferring and tuning their phenomenal catalytic properties, enabling active sites with otherwise similar primary coordination environments to perform a diverse array of biological functions. However, since the interactions beyond the primary coordination sphere are numerous and weak, it has been difficult to pinpoint structural features responsible for the tuning of activities of native enzymes. Designing artificial metalloenzymes (ArMs) offers an excellent basis to elucidate the roles of these interactions and to further develop practical biological catalysts. In this review, we highlight how the secondary coordination spheres of ArMs influence metal binding and catalysis, with particular focus on the use of native protein scaffolds as templates for the design of ArMs by either rational design aided by computational modeling, directed evolution, or a combination of both approaches. In describing successes in designing heme, nonheme Fe, and Cu metalloenzymes, heteronuclear metalloenzymes containing heme, and those ArMs containing other metal centers (including those with non-native metal ions and metallocofactors), we have summarized insights gained on how careful controls of the interactions in the secondary coordination sphere, including hydrophobic and hydrogen bonding interactions, allow the generation and tuning of these respective systems to approach, rival, and, in a few cases, exceed those of native enzymes. We have also provided an outlook on the remaining challenges in the field and future directions that will allow for a deeper understanding of the secondary coordination sphere a deeper understanding of the secondary coordintion sphere to be gained, and in turn to guide the design of a broader and more efficient variety of ArMs.
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Affiliation(s)
- Casey Van Stappen
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States
| | - Yunling Deng
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States
| | - Yiwei Liu
- Department of Chemistry, University of Illinois, Urbana-Champaign, 505 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Hirbod Heidari
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States
| | - Jing-Xiang Wang
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States
| | - Yu Zhou
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States
| | - Aaron P Ledray
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States
| | - Yi Lu
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States.,Department of Chemistry, University of Illinois, Urbana-Champaign, 505 South Mathews Avenue, Urbana, Illinois 61801, United States
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10
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Yu Y, Marshall NM, Garner DK, Nilges MJ, Lu Y. Tuning reduction potentials of type 1 copper center in azurin by replacing a histidine ligand with its isostructural analogues. J Inorg Biochem 2022; 234:111863. [DOI: 10.1016/j.jinorgbio.2022.111863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 05/02/2022] [Accepted: 05/08/2022] [Indexed: 11/16/2022]
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11
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Rajbongshi J, Das DK, Mazumdar S. Spectroscopic and electrochemical studies of the pH-Induced transition in the CuA centre from Thermus thermophilus. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2021.120749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Fedoretz-Maxwell BP, Shin CH, MacNeil GA, Worrall LJ, Park R, Strynadka NCJ, Walsby CJ, Warren JJ. The Impact of Second Coordination Sphere Methionine-Aromatic Interactions in Copper Proteins. Inorg Chem 2022; 61:5563-5571. [DOI: 10.1021/acs.inorgchem.2c00030] [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]
Affiliation(s)
- Brooklyn P. Fedoretz-Maxwell
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Catherine H. Shin
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Gregory A. MacNeil
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Liam J. Worrall
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Rachel Park
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Natalie C. J. Strynadka
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Charles J. Walsby
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Jeffrey J. Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
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13
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Di Rocco G, Battistuzzi G, Borsari M, Bortolotti CA, Ranieri A, Sola M. The enthalpic and entropic terms of the reduction potential of metalloproteins: Determinants and interplay. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214071] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Osella S. Artificial Photosynthesis: Is Computation Ready for the Challenge Ahead? NANOMATERIALS 2021; 11:nano11020299. [PMID: 33498961 PMCID: PMC7911014 DOI: 10.3390/nano11020299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 12/13/2022]
Abstract
A tremendous effort is currently devoted to the generation of novel hybrid materials with enhanced electronic properties for the creation of artificial photosynthetic systems. This compelling and challenging problem is well-defined from an experimental point of view, as the design of such materials relies on combining organic materials or metals with biological systems like light harvesting and redox-active proteins. Such hybrid systems can be used, e.g., as bio-sensors, bio-fuel cells, biohybrid photoelectrochemical cells, and nanostructured photoelectronic devices. Despite these efforts, the main bottleneck is the formation of efficient interfaces between the biological and the organic/metal counterparts for efficient electron transfer (ET). It is within this aspect that computation can make the difference and improve the current understanding of the mechanisms underneath the interface formation and the charge transfer efficiency. Yet, the systems considered (i.e., light harvesting protein, self-assembly monolayer and surface assembly) are more and more complex, reaching (and often passing) the limit of current computation power. In this review, recent developments in computational methods for studying complex interfaces for artificial photosynthesis will be provided and selected cases discussed, to assess the inherent ability of computation to leave a mark in this field of research.
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Affiliation(s)
- Silvio Osella
- Chemical and Biological Systems Simulation Lab, Center of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland
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15
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Koebke KJ, Alfaro VS, Pinter TBJ, Deb A, Lehnert N, Tard C, Penner-Hahn JE, Pecoraro VL. Traversing the Red-Green-Blue Color Spectrum in Rationally Designed Cupredoxins. J Am Chem Soc 2020; 142:15282-15294. [PMID: 32786767 DOI: 10.1021/jacs.0c04757] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Blue copper proteins have a constrained Cu(II) geometry that has proven difficult to recapitulate outside native cupredoxin folds. Previous work has successfully designed green copper proteins which could be tuned blue using exogenous ligands, but the question of how one can create a self-contained blue copper site within a de novo scaffold, especially one removed from a cupredoxin fold, remained. We have recently reported a red copper protein site within a three helical bundle scaffold which we later revisited and determined to be a nitrosocyanin mimic, with a CuHis2CysGlu binding site. We now report efforts to rationally design this construct toward either green or blue copper chromophores using mutation strategies that have proven successful in native cupredoxins. By rotating the metal binding site, we created a de novo green copper protein. This in turn was converted to a blue copper protein by removing an axial methionine. Following this rational sequence, we have successfully created red, green, and blue copper proteins within an alpha helical fold, enabling comparisons for the first time of their structure and function disconnected from the overall cupredoxin fold.
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Affiliation(s)
- Karl J Koebke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Victor Sosa Alfaro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Tyler B J Pinter
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Cédric Tard
- LCM, CNRS, Ecole Polytechnique, IP Paris, F-91128 Palaiseau, France
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vincent L Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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16
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Pinter TBJ, Koebke KJ, Pecoraro VL. Catalysis and Electron Transfer in De Novo Designed Helical Scaffolds. Angew Chem Int Ed Engl 2020; 59:7678-7699. [PMID: 31441170 PMCID: PMC7035182 DOI: 10.1002/anie.201907502] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Indexed: 12/31/2022]
Abstract
The relationship between protein structure and function is one of the greatest puzzles within biochemistry. De novo metalloprotein design is a way to wipe the board clean and determine what is required to build in function from the ground up in an unrelated structure. This Review focuses on protein design efforts to create de novo metalloproteins within alpha-helical scaffolds. Examples of successful designs include those with carbonic anhydrase or nitrite reductase activity by incorporating a ZnHis3 or CuHis3 site, or that recapitulate the spectroscopic properties of unique electron-transfer sites in cupredoxins (CuHis2 Cys) or rubredoxins (FeCys4 ). This work showcases the versatility of alpha helices as scaffolds for metalloprotein design and the progress that is possible through careful rational design. Our studies cover the invariance of carbonic anhydrase activity with different site positions and scaffolds, refinement of our cupredoxin models, and enhancement of nitrite reductase activity up to 1000-fold.
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Affiliation(s)
- Tyler B. J. Pinter
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States, 48109-1055
| | - Karl J. Koebke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States, 48109-1055
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States, 48109-1055
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17
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Pinter TBJ, Koebke KJ, Pecoraro VL. Katalyse und Elektronentransfer in helikalen De‐novo‐Gerüststrukturen. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201907502] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tyler B. J. Pinter
- Department of Chemistry University of Michigan Ann Arbor Michigan 48109-1055 USA
| | - Karl J. Koebke
- Department of Chemistry University of Michigan Ann Arbor Michigan 48109-1055 USA
| | - Vincent L. Pecoraro
- Department of Chemistry University of Michigan Ann Arbor Michigan 48109-1055 USA
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18
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Sinicropi A. DFT modeling of structures and redox potentials of wild-type, Nickel-substituted and mutated (N47S/M121L, HPAz) Azurin. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.08.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Fowler NJ, Blanford CF, Warwicker J, de Visser SP. Prediction of Reduction Potentials of Copper Proteins with Continuum Electrostatics and Density Functional Theory. Chemistry 2017; 23:15436-15445. [PMID: 28815759 PMCID: PMC5698706 DOI: 10.1002/chem.201702901] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Indexed: 12/20/2022]
Abstract
Blue copper proteins, such as azurin, show dramatic changes in Cu2+/Cu+ reduction potential upon mutation over the full physiological range. Hence, they have important functions in electron transfer and oxidation chemistry and have applications in industrial biotechnology. The details of what determines these reduction potential changes upon mutation are still unclear. Moreover, it has been difficult to model and predict the reduction potential of azurin mutants and currently no unique procedure or workflow pattern exists. Furthermore, high‐level computational methods can be accurate but are too time consuming for practical use. In this work, a novel approach for calculating reduction potentials of azurin mutants is shown, based on a combination of continuum electrostatics, density functional theory and empirical hydrophobicity factors. Our method accurately reproduces experimental reduction potential changes of 30 mutants with respect to wildtype within experimental error and highlights the factors contributing to the reduction potential change. Finally, reduction potentials are predicted for a series of 124 new mutants that have not yet been investigated experimentally. Several mutants are identified that are located well over 10 Å from the copper center that change the reduction potential by more than 85 mV. The work shows that secondary coordination sphere mutations mostly lead to long‐range electrostatic changes and hence can be modeled accurately with continuum electrostatics.
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Affiliation(s)
- Nicholas J Fowler
- Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Christopher F Blanford
- Manchester Institute of Biotechnology and School of Materials, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Jim Warwicker
- Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Sam P de Visser
- Manchester Institute of Biotechnology, and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
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20
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Manesis AC, O'Connor MJ, Schneider CR, Shafaat HS. Multielectron Chemistry within a Model Nickel Metalloprotein: Mechanistic Implications for Acetyl-CoA Synthase. J Am Chem Soc 2017; 139:10328-10338. [PMID: 28675928 DOI: 10.1021/jacs.7b03892] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The acetyl coenzyme A synthase (ACS) enzyme plays a central role in the metabolism of anaerobic bacteria and archaea, catalyzing the reversible synthesis of acetyl-CoA from CO and a methyl group through a series of nickel-based organometallic intermediates. Owing to the extreme complexity of the native enzyme systems, the mechanism by which this catalysis occurs remains poorly understood. In this work, we have developed a protein-based model for the NiP center of acetyl coenzyme A synthase using a nickel-substituted azurin protein (NiAz). NiAz is the first model nickel protein system capable of accessing three (NiI/NiII/NiIII) distinct oxidation states within a physiological potential range in aqueous solution, a critical feature for achieving organometallic ACS activity, and binds CO and -CH3 groups with biologically relevant affinity. Characterization of the NiI-CO species through spectroscopic and computational techniques reveals fundamentally similar features between the model NiAz system and the native ACS enzyme, highlighting the potential for related reactivity in this model protein. This work provides insight into the enzymatic process, with implications toward engineering biological catalysts for organometallic processes.
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Affiliation(s)
- Anastasia C Manesis
- The Ohio State University , 100 West 18th Avenue, Newman & Wolfrom Laboratory of Chemistry, Columbus, Ohio 43210, United States
| | - Matthew J O'Connor
- The Ohio State University , 100 West 18th Avenue, Newman & Wolfrom Laboratory of Chemistry, Columbus, Ohio 43210, United States
| | - Camille R Schneider
- The Ohio State University , 100 West 18th Avenue, Newman & Wolfrom Laboratory of Chemistry, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- The Ohio State University , 100 West 18th Avenue, Newman & Wolfrom Laboratory of Chemistry, Columbus, Ohio 43210, United States
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21
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Roger M, Sciara G, Biaso F, Lojou E, Wang X, Bauzan M, Giudici-Orticoni MT, Vila AJ, Ilbert M. Impact of copper ligand mutations on a cupredoxin with a green copper center. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:351-359. [DOI: 10.1016/j.bbabio.2017.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/10/2017] [Accepted: 02/14/2017] [Indexed: 11/26/2022]
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22
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Tian S, Liu J, Cowley RE, Hosseinzadeh P, Marshall NM, Yu Y, Robinson H, Nilges MJ, Blackburn NJ, Solomon EI, Lu Y. Reversible S-nitrosylation in an engineered azurin. Nat Chem 2016; 8:670-7. [PMID: 27325093 PMCID: PMC4918514 DOI: 10.1038/nchem.2489] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 03/02/2016] [Indexed: 12/20/2022]
Abstract
S-Nitrosothiols are known as reagents for NO storage and transportation and as regulators in many physiological processes. Although the S-nitrosylation catalysed by haem proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here, we report reversible insertion of NO into a copper-thiolate bond in an engineered copper centre in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential by deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine in metalloproteins, but also shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)-S(Cys)NO species. The fast, efficient and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions.
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Affiliation(s)
- Shiliang Tian
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | - Jing Liu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | - Ryan E. Cowley
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Parisa Hosseinzadeh
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | - Nicholas M. Marshall
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | - Yang Yu
- Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | - Howard Robinson
- Department of Biology, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Mark J. Nilges
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | - Ninian J. Blackburn
- Institute of Environmental Health, Oregon Health & Sciences University, Portland, Oregon 97239, USA
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
- Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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23
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Hosseinzadeh P, Lu Y. Design and fine-tuning redox potentials of metalloproteins involved in electron transfer in bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:557-581. [PMID: 26301482 PMCID: PMC4761536 DOI: 10.1016/j.bbabio.2015.08.006] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 08/20/2015] [Indexed: 12/25/2022]
Abstract
Redox potentials are a major contributor in controlling the electron transfer (ET) rates and thus regulating the ET processes in the bioenergetics. To maximize the efficiency of the ET process, one needs to master the art of tuning the redox potential, especially in metalloproteins, as they represent major classes of ET proteins. In this review, we first describe the importance of tuning the redox potential of ET centers and its role in regulating the ET in bioenergetic processes including photosynthesis and respiration. The main focus of this review is to summarize recent work in designing the ET centers, namely cupredoxins, cytochromes, and iron-sulfur proteins, and examples in design of protein networks involved these ET centers. We then discuss the factors that affect redox potentials of these ET centers including metal ion, the ligands to metal center and interactions beyond the primary ligand, especially non-covalent secondary coordination sphere interactions. We provide examples of strategies to fine-tune the redox potential using both natural and unnatural amino acids and native and nonnative cofactors. Several case studies are used to illustrate recent successes in this area. Outlooks for future endeavors are also provided. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.
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Affiliation(s)
- Parisa Hosseinzadeh
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews St., Urbana, IL, 61801, USA
| | - Yi Lu
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews St., Urbana, IL, 61801, USA.
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24
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Hosseinzadeh P, Mirts EN, Pfister TD, Gao YG, Mayne C, Robinson H, Tajkhorshid E, Lu Y. Enhancing Mn(II)-Binding and Manganese Peroxidase Activity in a Designed Cytochrome c Peroxidase through Fine-Tuning Secondary-Sphere Interactions. Biochemistry 2016; 55:1494-502. [PMID: 26885726 DOI: 10.1021/acs.biochem.5b01299] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Noncovalent second-shell interactions are important in controlling metal-binding affinity and activity in metalloenzymes, but fine-tuning these interactions in designed metalloenzymes has not been fully explored. As a result, most designed metalloenzymes have low metal-binding affinity and activity. Here we identified three mutations in the second coordination shell of an engineered Mn(II)-binding site in cytochrome c peroxidase (called MnCcP.1, containing Glu45, Glu37, and Glu181 ligands) that mimics the native manganese peroxidase (MnP), and explored their effects on both Mn(II)-binding affinity and MnP activity. First, removing a hydrogen bond to Glu45 through Tyr36Phe mutation enhanced Mn(II)-binding affinity, as evidenced by a 2.8-fold decrease in the KM of Mn(II) oxidation. Second, introducing a salt bridge through Lys179Arg mutation improved Glu35 and Glu181 coordination to Mn(II), decreasing KM 2.6-fold. Third, eliminating a steric clash that prevented Glu37 from orienting toward Mn(II) resulted in an 8.6-fold increase in kcat/KM, arising primarily from a 3.6-fold decrease in KM, with a KM value comparable to that of the native enzyme (0.28 mM vs 0.19 mM for Pleurotus eryngii MnP PS3). We further demonstrated that while the effects of Tyr36Phe and Lys179Arg mutations are additive, because involved in secondary-shell interactions to different ligands, other combinations of mutations were antagonistic because they act on different aspects of the Mn(II) coordination at the same residues. Finally, we showed that these MnCcP variants are functional models of MnP that mimic its activity in both Mn(II) oxidation and degradation of a phenolic lignin model compound and kraft lignin. In addition to achieving KM in a designed protein that is similar to the that of native enzyme, our results offer molecular insight into the role of noncovalent interactions around metal-binding sites for improving metal binding and overall activity; such insight can be applied to rationally enhance these properties in other metalloenzymes and their models.
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Affiliation(s)
| | | | | | | | | | - Howard Robinson
- Department of Biology, Brookhaven National Laboratory , Upton, New York 11973, United States
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25
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Nóbrega CS, Saraiva IH, Carreira C, Devreese B, Matzapetakis M, Pauleta SR. The solution structure of the soluble form of the lipid-modified azurin from Neisseria gonorrhoeae , the electron donor of cytochrome c peroxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:169-176. [DOI: 10.1016/j.bbabio.2015.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 10/25/2015] [Accepted: 11/13/2015] [Indexed: 12/26/2022]
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26
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Design of a single protein that spans the entire 2-V range of physiological redox potentials. Proc Natl Acad Sci U S A 2015; 113:262-7. [PMID: 26631748 DOI: 10.1073/pnas.1515897112] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The reduction potential (E°') is a critical parameter in determining the efficiency of most biological and chemical reactions. Biology employs three classes of metalloproteins to cover the majority of the 2-V range of physiological E°'s. An ultimate test of our understanding of E°' is to find out the minimal number of proteins and their variants that can cover this entire range and the structural features responsible for the extreme E°'. We report herein the design of the protein azurin to cover a range from +970 mV to -954 mV vs. standard hydrogen electrode (SHE) by mutating only five residues and using two metal ions. Spectroscopic methods have revealed geometric parameters important for the high E°'. The knowledge gained and the resulting water-soluble redox agents with predictable E°'s, in the same scaffold with the same surface properties, will find wide applications in chemical, biochemical, biophysical, and biotechnological fields.
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27
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Plegaria JS, Duca M, Tard C, Friedlander TJ, Deb A, Penner-Hahn JE, Pecoraro VL. De novo design and characterization of copper metallopeptides inspired by native cupredoxins. Inorg Chem 2015; 54:9470-82. [PMID: 26381361 DOI: 10.1021/acs.inorgchem.5b01330] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using de novo protein design, we incorporated a copper metal binding site within the three-helix bundle α3D (Walsh et al. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 5486-5491) to assess whether a cupredoxin center within an α-helical domain could mimic the spectroscopic, structural, and redox features of native type-1 copper (CuT1) proteins. We aimed to determine whether a CuT1 center could be realized in a markedly different scaffold rather than the native β-barrel fold and whether the characteristic short Cu-S bond (2.1-2.2 Å) and positive reduction potentials could be decoupled from the spectroscopic properties (ε600 nm = 5000 M(-1) cm(-1)) of such centers. We incorporated 2HisCys(Met) residues in three distinct α3D designs designated core (CR), chelate (CH), and chelate-core (ChC). XAS analysis revealed a coordination environment similar to reduced CuT1 proteins, producing Cu-S(Cys) bonds ranging from 2.16 to 2.23 Å and Cu-N(His) bond distances of 1.92-1.99 Å. However, Cu(II) binding to the CR and CH constructs resulted in tetragonal type-2 copper-like species, displaying an intense absorption band between 380 and 400 nm (>1500 M(-1) cm(-1)) and A|| values of (150-185) × 10(-4) cm(-4). The ChC construct, which possesses a metal-binding site deeper in its helical bundle, yielded a CuT1-like brown copper species, with two absorption bands at 401 (4429 M(-1) cm(-1)) and 499 (2020 M(-1) cm(-1)) nm and an A|| value ∼30 × 10(-4) cm(-4) greater than its native counterparts. Electrochemical studies demonstrated reduction potentials of +360 to +460 mV (vs NHE), which are within the observed range for azurin and plastocyanin. These observations showed that the designed metal binding sites lacked the necessary rigidity to enforce the appropriate structural constraints for a Cu(II) chromophore (EPR and UV-vis); however, the Cu(I) structural environment and the high positive potential of CuT1 centers were recapitulated within the α-helical bundle of α3D.
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Affiliation(s)
| | - Matteo Duca
- Laboratoire d'Electrochimie Moléculaire, UMR 7591, CNRS, Université Paris Diderot, Sorbonne Paris Cité , 15 Rue Jean Antoine de Baïf, F-75205 Paris Cedex 13, France
| | - Cédric Tard
- Laboratoire d'Electrochimie Moléculaire, UMR 7591, CNRS, Université Paris Diderot, Sorbonne Paris Cité , 15 Rue Jean Antoine de Baïf, F-75205 Paris Cedex 13, France
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28
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Sitarz AK, Mikkelsen JD, Meyer AS. Structure, functionality and tuning up of laccases for lignocellulose and other industrial applications. Crit Rev Biotechnol 2015; 36:70-86. [DOI: 10.3109/07388551.2014.949617] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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29
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Farver O, Hosseinzadeh P, Marshall NM, Wherland S, Lu Y, Pecht I. Long-Range Electron Transfer in Engineered Azurins Exhibits Marcus Inverted Region Behavior. J Phys Chem Lett 2015; 6:100-105. [PMID: 26263097 DOI: 10.1021/jz5022685] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The Marcus theory of electron transfer (ET) predicts that while the ET rate constants increase with rising driving force until it equals a reaction's reorganization energy, at higher driving force the ET rate decreases, having reached the Marcus inverted region. While experimental evidence of the inverted region has been reported for organic and inorganic ET reactions as well as for proteins conjugated with ancillary redox moieties, evidence of the inverted region in a "protein-only" system has remained elusive. We herein provide such evidence in a series of nonderivatized proteins. These results may facilitate the design of ET centers for future applications such as advanced energy conversions.
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Affiliation(s)
- Ole Farver
- †Department of Analytical and Bioinorganic Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen 2100, Denmark
| | | | | | - Scot Wherland
- ∥Department of Chemistry, Washington State University, PO Box 644630, Pullman, Washington 99164, United States
| | | | - Israel Pecht
- §Department of Immunology, Weizmann Institute of Science, Wolfson Building, Rehovot 76100, Israel
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30
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King JD, Harrington L, Lada BM, He G, Cooley JW, Blankenship RE. Site-directed mutagenesis of the highly perturbed copper site of auracyanin D. Arch Biochem Biophys 2014; 564:237-43. [DOI: 10.1016/j.abb.2014.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/01/2014] [Accepted: 10/07/2014] [Indexed: 10/24/2022]
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31
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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: 559] [Impact Index Per Article: 55.9] [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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32
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Yu F, Cangelosi VM, Zastrow ML, Tegoni M, Plegaria JS, Tebo AG, Mocny CS, Ruckthong L, Qayyum H, Pecoraro VL. Protein design: toward functional metalloenzymes. Chem Rev 2014; 114:3495-578. [PMID: 24661096 PMCID: PMC4300145 DOI: 10.1021/cr400458x] [Citation(s) in RCA: 340] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Fangting Yu
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | | | | | | | - Alison G. Tebo
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Leela Ruckthong
- University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hira Qayyum
- University of Michigan, Ann Arbor, Michigan 48109, United States
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33
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Filip J, Tkac J. The pH dependence of the cathodic peak potential of the active sites in bilirubin oxidase. Bioelectrochemistry 2014; 96:14-20. [DOI: 10.1016/j.bioelechem.2013.11.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 11/12/2013] [Accepted: 11/29/2013] [Indexed: 02/08/2023]
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34
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Marmisollé WA, Florit MI, Posadas D. Coupling between proton binding and redox potential in electrochemically active macromolecules. The example of Polyaniline. J Electroanal Chem (Lausanne) 2013. [DOI: 10.1016/j.jelechem.2013.08.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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35
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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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36
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Vita N, Brubach JB, Hienerwadel R, Bremond N, Berthomieu D, Roy P, Berthomieu C. Electrochemically Induced Far-Infrared Difference Spectroscopy on Metalloproteins Using Advanced Synchrotron Technology. Anal Chem 2013; 85:2891-8. [DOI: 10.1021/ac303511g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Nicolas Vita
- Lab Interactions Protein Metal, Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Saint-Paul-lez-Durance,
F-13108, France
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
- Société Civile Synchrotron SOLEIL, L’Orme des Merisiers,
St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Jean-Blaise Brubach
- Société Civile Synchrotron SOLEIL, L’Orme des Merisiers,
St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Rainer Hienerwadel
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Lab Genet Biophys Plantes, Aix-Marseille Université, Marseille, F-13009,
France
- Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Marseille,
F-13009, France
| | - Nicolas Bremond
- Lab Interactions Protein Metal, Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Saint-Paul-lez-Durance,
F-13108, France
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
| | - Dorothée Berthomieu
- Institut Charles Gerhardt, MACS, UMR 5253 CNRS-ENSCM-UM1-UM2, 8, rue
de l’Ecole Normale, 34296 Montpellier Cedex 5, France
| | - Pascale Roy
- Société Civile Synchrotron SOLEIL, L’Orme des Merisiers,
St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Catherine Berthomieu
- Lab Interactions Protein Metal, Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Saint-Paul-lez-Durance,
F-13108, France
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
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37
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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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38
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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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39
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New SY, Marshall NM, Hor TSA, Xue F, Lu Y. Redox tuning of two biological copper centers through non-covalent interactions: same trend but different magnitude. Chem Commun (Camb) 2012; 48:4217-9. [DOI: 10.1039/c2cc30901g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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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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41
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Ullmann RT, Ullmann GM. Coupling of Protonation, Reduction, and Conformational Change in azurin from Pseudomonas aeruginosa Investigated with Free Energy Measures of Cooperativity. J Phys Chem B 2011; 115:10346-59. [DOI: 10.1021/jp204644h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. Thomas Ullmann
- Structural Biology/Bioinformatics, University of Bayreuth, Universitätsstrasse 30, BGI, 95447 Bayreuth, Germany
| | - G. Matthias Ullmann
- Structural Biology/Bioinformatics, University of Bayreuth, Universitätsstrasse 30, BGI, 95447 Bayreuth, Germany
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42
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Lancaster KM, Sproules S, Palmer JH, Richards JH, Gray HB. Outer-sphere effects on reduction potentials of copper sites in proteins: the curious case of high potential type 2 C112D/M121E Pseudomonas aeruginosa azurin. J Am Chem Soc 2011; 132:14590-5. [PMID: 20879734 DOI: 10.1021/ja105731x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Redox and spectroscopic (electronic absorption, multifrequency electron paramagnetic resonance (EPR), and X-ray absorption) properties together with X-ray crystal structures are reported for the type 2 Cu(II) C112D/M121E variant of Pseudomonas aeruginosa azurin. The results suggest that Cu(II) is constrained from interaction with the proximal glutamate; this structural frustration implies a "rack" mechanism for the 290 mV (vs NHE) reduction potential measured at neutral pH. At high pH (∼9), hydrogen bonding in the outer coordination sphere is perturbed to allow axial glutamate ligation to Cu(II), with a decrease in potential to 119 mV. These results highlight the role played by outer-sphere interactions, and the structural constraints they impose, in determining the redox behavior of transition metal protein cofactors.
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Affiliation(s)
- Kyle M Lancaster
- Beckman Institute, California Institute of Technology, Pasadena, California 91125, USA.
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43
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Abstract
Copper proteins play key roles in biological processes such as electron transfer and dioxygen activation; the active site of each of these proteins is classified as either type 1, 2, or 3, depending on its optical and electron paramagnetic resonance properties. We have built a new type of site that we call “type zero copper” by incorporating leucine, isoleucine, or phenylalanine in place of methionine at position 121 in C112D Pseudomonas aeruginosa azurin. X-ray crystallographic analysis shows that these sites adopt distorted tetrahedral geometries, with an unusually short Cu-O(G45 carbonyl) bond (2.35–2.55 Å). Relatively weak absorption near 800 nm and narrow parallel hyperfine splittings in EPR spectra are the spectroscopic signatures of type zero copper. Copper K-edge x-ray absorption spectra suggest elevated Cu(II) 4p character in the d-electron ground state. Cyclic voltammetric experiments demonstrate that the electron transfer reactivities of type zero azurins are enhanced relative to that of the corresponding type 2 (C112D) protein.
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Affiliation(s)
- Kyle M Lancaster
- California Institute of Technology, Pasadena, California 91125, USA
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44
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Biological Outer-Sphere Coordination. MOLECULAR ELECTRONIC STRUCTURES OF TRANSITION METAL COMPLEXES I 2011. [DOI: 10.1007/430_2011_49] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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45
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Cracknell JA, McNamara TP, Lowe ED, Blanford CF. Bilirubin oxidase from Myrothecium verrucaria: X-ray determination of the complete crystal structure and a rational surface modification for enhanced electrocatalytic O2 reduction. Dalton Trans 2011; 40:6668-75. [DOI: 10.1039/c0dt01403f] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Clark KM, Yu Y, Marshall NM, Sieracki NA, Nilges MJ, Blackburn NJ, van der Donk WA, Lu Y. Transforming a blue copper into a red copper protein: engineering cysteine and homocysteine into the axial position of azurin using site-directed mutagenesis and expressed protein ligation. J Am Chem Soc 2010; 132:10093-101. [PMID: 20608676 DOI: 10.1021/ja102632p] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Interactions of the axial ligand with its blue copper center are known to be important in tuning spectroscopic and redox properties of cupredoxins. While conversion of the blue copper center with a weak axial ligand to a green copper center containing a medium strength axial ligand has been demonstrated in cupredoxins, converting the blue copper center to a red copper center with a strong axial ligand has not been reported. Here we show that replacing Met121 in azurin from Pseudomonas aeruginosa with Cys caused an increased ratio (R(L)) of absorption at 447 nm over that at 621 nm. Whereas no axial Cu-S(Cys121) interaction in Met121Cys was detectable by extended X-ray absorption fine structure (EXAFS) spectroscopy at pH 5, similar to what was observed in native azurin with Met121 as the axial ligand, the Cu-S(Cys121) interaction at 2.74 A is clearly visible at higher pH. Despite the higher R(L) and stronger axial Cys121 interaction with Cu(II) ion, the Met121Cys variant remains largely a type 1 copper protein at low pH (with hyperfine coupling constant A( parallel) = 54 x 10(-4) cm(-1) at pH 4 and 5), or distorted type 1 or green copper protein at high pH (A(parallel) = 87 x 10(-4) cm(-1) at pH 8 and 9), attributable to the relatively long distance between the axial ligand and copper and the constraint placed by the protein scaffold. To shorten the distance between axial ligand and copper, we replaced Met121 with a nonproteinogenic amino acid homocysteine that contains an extra methylene group, resulting in a variant whose spectra (R(L)= 1.5, and A(parallel) = 180 x 10(-4) cm(-1)) and Cu-S(Cys) distance (2.22 A) are very similar to those of the red copper protein nitrosocyanin. Replacing Met121 with Cys or homocysteine resulted in lowering of the reduction potential from 222 mV in the native azurin to 95 +/- 3 mV for Met121Cys azurin and 113 +/- 6 mV for Met121Hcy azurin at pH 7. The results strongly support the "coupled distortion" model that helps explain axial ligand tuning of spectroscopic properties in cupredoxins, and demonstrate the power of using unnatural amino acids to address critical chemical biological questions.
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Affiliation(s)
- Kevin M Clark
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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47
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Lancaster KM, Yokoyama K, Richards JH, Winkler JR, Gray HB. High-potential C112D/M121X (X = M, E, H, L) Pseudomonas aeruginosa azurins. Inorg Chem 2010; 48:1278-80. [PMID: 19113863 DOI: 10.1021/ic802322e] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Site-directed mutagenesis of Pseudomonas aeruginosa azurin C112D at the M121 position has afforded a series of proteins with elevated Cu(II/I) reduction potentials relative to the Cu(II) aquo ion. The high potential and low axial hyperfine splitting (Cu(II) electron paramagnetic resonance A( parallel)) of the C112D/M121L protein are remarkably similar to features normally associated with type 1 copper centers.
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Affiliation(s)
- Kyle M Lancaster
- Beckman Institute, California Institute of Technology, Pasadena, California 91125, USA
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48
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49
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Savelieff MG, Lu Y. CuA centers and their biosynthetic models in azurin. J Biol Inorg Chem 2010; 15:461-83. [DOI: 10.1007/s00775-010-0625-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2009] [Accepted: 01/20/2010] [Indexed: 11/28/2022]
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50
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Choi M, Sukumar N, Liu A, Davidson VL. Defining the role of the axial ligand of the type 1 copper site in amicyanin by replacement of methionine with leucine. Biochemistry 2009; 48:9174-84. [PMID: 19715303 DOI: 10.1021/bi900836h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of replacing the axial methionine ligand of the type 1 copper site with leucine on the structure and function of amicyanin have been characterized. The crystal structures of the oxidized and reduced forms of the protein reveal that the copper site is now tricoordinate with no axial ligand, and that the copper coordination distances for the two ligands provided by histidines are significantly increased. Despite these structural changes, the absorption and EPR spectra of M98L amicyanin are only slightly altered and still consistent with that of a typical type 1 site. The oxidation-reduction midpoint potential (E(m)) value becomes 127 mV more positive as a consequence of the M98L mutation, most likely because of the increased hydrophobicity of the copper site. The most dramatic effect of the mutation was on the electron transfer (ET) reaction from reduced M98L amicyanin to cytochrome c(551i) within the protein ET complex. The rate decreased 435-fold, which was much more than expected from the change in E(m). Examination of the temperature dependence of the ET rate (k(ET)) revealed that the mutation caused a 13.6-fold decrease in the electronic coupling (H(AB)) for the reaction. A similar decrease was predicted from a comparative analysis of the crystal structures of reduced M98L and native amicyanins. The most direct route of ET for this reaction is through the Met98 ligand. Inspection of the structures suggests that the major determinant of the large decrease in the experimentally determined values of H(AB) and k(ET) is the increased distance from the copper to the protein within the type 1 site of M98L amicyanin.
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Affiliation(s)
- Moonsung Choi
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, Mississippi 39216-4505, USA
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