1
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Valetti F, Morra S, Barbieri L, Dezzani S, Ratto A, Catucci G, Sadeghi SJ, Gilardi G. Oxygen-resistant [FeFe]hydrogenases: new biocatalysis tools for clean energy and cascade reactions. Faraday Discuss 2024. [PMID: 38836410 DOI: 10.1039/d4fd00010b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
The use of enzymes to generate hydrogen, instead of using rare metal catalysts, is an exciting area of study in modern biochemistry and biotechnology, as well as biocatalysis driven by sustainable hydrogen. Thus far, the oxygen sensitivity of the fastest hydrogen-producing/exploiting enzymes, [FeFe]hydrogenases, has hindered their practical application, thereby restricting innovations mainly to their [NiFe]-based, albeit slower, counterparts. Recent exploration of the biodiversity of clostridial hydrogen-producing enzymes has yielded the isolation of representatives from a relatively understudied group. These enzymes possess an inherent defense mechanism against oxygen-induced damage. This discovery unveils fresh opportunities for applications such as electrode interfacing, biofuel cells, immobilization, and entrapment for enhanced stability in practical uses. Furthermore, it suggests potential combinations with cascade reactions for CO2 conversion or cofactor regeneration, like NADPH, facilitating product separation in biotechnological processes. This work provides an overview of this new class of biocatalysts, incorporating unpublished protein engineering strategies to further investigate the dynamic mechanism of oxygen protection and to address crucial details remaining elusive such as still unidentified switching hot-spots and their effects. Variants with improved kcat as well as chimeric versions with promising features to attain gain-of-function variants and applications in various biotechnological processes are also presented.
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Affiliation(s)
- Francesca Valetti
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
| | - Simone Morra
- Faculty of Engineering, University of Nottingham, Nottingham, UK
| | - Lisa Barbieri
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
- University School for Advanced Studies IUSS Pavia, Italy
| | - Sabrina Dezzani
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
- University School for Advanced Studies IUSS Pavia, Italy
| | - Alessandro Ratto
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
| | - Gianluca Catucci
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
| | - Sheila J Sadeghi
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
| | - Gianfranco Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy.
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2
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Lam Q, Van Stappen C, Lu Y, Dikanov SA. HYSCORE and QM/MM Studies of Second Sphere Variants of the Type 1 Copper Site in Azurin: Influence of Mutations on the Hyperfine Couplings of Remote Nitrogens. J Phys Chem B 2024; 128:3350-3359. [PMID: 38564809 DOI: 10.1021/acs.jpcb.3c08194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Secondary coordination sphere (SCS) interactions have been shown to play important roles in tuning reduction potentials and electron transfer (ET) properties of the Type 1 copper proteins, but the precise roles of these interactions are not fully understood. In this work, we examined the influence of F114P, F114N, and N47S mutations in the SCS on the electronic structure of the T1 copper center in azurin (Az) by studying the hyperfine couplings of (i) histidine remote Nε nitrogens and (ii) the amide Np using the two-dimensional (2D) pulsed electron paramagnetic resonance (EPR) technique HYSCORE (hyperfine sublevel correlation) combined with quantum mechanics/molecular mechanics (QM/MM) and DLPNO-CCSD calculations. Our data show that some components of hyperfine tensor and isotropic coupling in N47SAz and F114PAz (but not F114NAz) deviate by up to ∼±20% from WTAz, indicating that these mutations significantly influence the spin density distribution between the CuII site and coordinating ligands. Furthermore, our calculations support the assignment of Np to the backbone amide of residue 47 (both in Asn and Ser variants). Since the spin density distributions play an important role in tuning the covalency of the Cu-Scys bond of Type 1 copper center that has been shown to be crucial in controlling the reduction potentials, this study provides additional insights into the electron spin factor in tuning the reduction potentials and ET properties.
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Affiliation(s)
- Quan Lam
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Casey Van Stappen
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yi Lu
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sergei A Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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3
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Ullrich SR, Fuchs H, Ashworth-Güth C. Electrochemical and structural characterization of recombinant respiratory proteins of the acidophilic iron oxidizer Ferrovum sp. PN-J47-F6 suggests adaptations to the acidic pH at protein level. Front Microbiol 2024; 15:1357152. [PMID: 38384274 PMCID: PMC10879576 DOI: 10.3389/fmicb.2024.1357152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
The tendency of the periplasmic redox proteins in acidophiles to have more positive redox potentials (Em) than their homologous counterparts in neutrophiles suggests an adaptation to acidic pH at protein level, since thermodynamics of electron transfer processes are also affected by acidic pH. Since this conclusion is mainly based on the electrochemical characterization of redox proteins from extreme acidophiles of the genus Acidithiobacillus, we aimed to characterize three recombinant redox proteins of the more moderate acidophile Ferrovum sp. PN-J47-F6. We applied protein film voltammetry and linear sweep voltammetry coupled to UV/Vis spectroscopy to characterize the redox behavior of HiPIP-41, CytC-18, and CytC-78, respectively. The Em-values of HiPIP-41 (571 ± 16 mV), CytC-18 (276 ± 8 mV, 416 ± 2 mV), and CytC-78 (308 ± 7 mV, 399 ± 7 mV) were indeed more positive than those of homologous redox proteins in neutrophiles. Moreover, our findings suggest that the adaptation of redox proteins with respect to their Em occurs more gradually in response to the pH, since there are also differences between moderate and more extreme acidophiles. In order to address structure function correlations in these redox proteins with respect to structural features affecting the Em, we conducted a comparative structural analysis of the Ferrovum-derived redox proteins and homologs of Acidithiobacillus spp. and neutrophilic proteobacteria. Hydrophobic contacts in the redox cofactor binding pockets resulting in a low solvent accessibility appear to be the major factor contributing to the more positive Em-values in acidophile-derived redox proteins. While additional cysteines in HiPIPs of acidophiles might increase the effective shielding of the [4Fe-4S]-cofactor, the tight shielding of the heme centers in acidophile-derived cytochromes is achieved by a drastic increase in hydrophobic contacts (A.f. Cyc41), and by a larger fraction of aromatic residues in the binding pockets (CytC-18, CytC-78).
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Affiliation(s)
- Sophie R. Ullrich
- Environmental Microbiology Group, Institute for Biological Sciences, TU Bergakademie Freiberg, Freiberg, Germany
- Biohydrometallurgy Group, Institute for Biological Sciences, TU Bergakademie Freiberg, Freiberg, Germany
| | - Helena Fuchs
- Biohydrometallurgy Group, Institute for Biological Sciences, TU Bergakademie Freiberg, Freiberg, Germany
| | - Charlotte Ashworth-Güth
- Salt and Mineral Chemistry Group, Institute for Inorganic Chemistry, TU Bergakademie Freiberg, Freiberg, Germany
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4
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Roger M, Leone P, Blackburn NJ, Horrell S, Chicano TM, Biaso F, Giudici-Orticoni MT, Abriata LA, Hura GL, Hough MA, Sciara G, Ilbert M. Beyond the coupled distortion model: structural analysis of the single domain cupredoxin AcoP, a green mononuclear copper centre with original features. Dalton Trans 2024; 53:1794-1808. [PMID: 38170898 PMCID: PMC10804444 DOI: 10.1039/d3dt03372d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024]
Abstract
Cupredoxins are widely occurring copper-binding proteins with a typical Greek-key beta barrel fold. They are generally described as electron carriers that rely on a T1 copper centre coordinated by four ligands provided by the folded polypeptide. The discovery of novel cupredoxins demonstrates the high diversity of this family, with variations in terms of copper-binding ligands, copper centre geometry, redox potential, as well as biological function. AcoP is a periplasmic cupredoxin belonging to the iron respiratory chain of the acidophilic bacterium Acidithiobacillus ferrooxidans. AcoP presents original features, including high resistance to acidic pH and a constrained green-type copper centre of high redox potential. To understand the unique properties of AcoP, we undertook structural and biophysical characterization of wild-type AcoP and of two Cu-ligand mutants (H166A and M171A). The crystallographic structures, including native reduced AcoP at 1.65 Å resolution, unveil a typical cupredoxin fold. The presence of extended loops, never observed in previously characterized cupredoxins, might account for the interaction of AcoP with physiological partners. The Cu-ligand distances, determined by both X-ray diffraction and EXAFS, show that the AcoP metal centre seems to present both T1 and T1.5 features, in turn suggesting that AcoP might not fit well to the coupled distortion model. The crystal structures of two AcoP mutants confirm that the active centre of AcoP is highly constrained. Comparative analysis with other cupredoxins of known structures, suggests that in AcoP the second coordination sphere might be an important determinant of active centre rigidity due to the presence of an extensive hydrogen bond network. Finally, we show that other cupredoxins do not perfectly follow the coupled distortion model as well, raising the suspicion that further alternative models to describe copper centre geometries need to be developed, while the importance of rack-induced contributions should not be underestimated.
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Affiliation(s)
- Magali Roger
- CNRS, Aix-Marseille University, Bioenergetic and Protein Engineering Laboratory, BIP UMR 7281, Mediterranean Institute of Microbiology, 13009 Marseille, France.
| | - Philippe Leone
- CNRS, Aix-Marseille University, Laboratoire d'Ingénierie des Systèmes Macromoléculaires, LISM UMR7255, 13009 Marseille, France
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Sam Horrell
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Tadeo Moreno Chicano
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
| | - Frédéric Biaso
- CNRS, Aix-Marseille University, Bioenergetic and Protein Engineering Laboratory, BIP UMR 7281, Mediterranean Institute of Microbiology, 13009 Marseille, France.
| | - Marie-Thérèse Giudici-Orticoni
- CNRS, Aix-Marseille University, Bioenergetic and Protein Engineering Laboratory, BIP UMR 7281, Mediterranean Institute of Microbiology, 13009 Marseille, France.
| | - Luciano A Abriata
- Laboratory for Biomolecular Modeling and Protein Purification and Structure Core Facility, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Greg L Hura
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Michael A Hough
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Giuliano Sciara
- CNRS, Aix-Marseille University, Bioenergetic and Protein Engineering Laboratory, BIP UMR 7281, Mediterranean Institute of Microbiology, 13009 Marseille, France.
- Aix Marseille Univ, INRAE, BBF UMR1163, Biodiversité et Biotechnologie Fongiques, 13288 Marseille, France
| | - Marianne Ilbert
- CNRS, Aix-Marseille University, Bioenergetic and Protein Engineering Laboratory, BIP UMR 7281, Mediterranean Institute of Microbiology, 13009 Marseille, France.
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5
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McGuinness KN, Fehon N, Feehan R, Miller M, Mutter AC, Rybak LA, Nam J, AbuSalim JE, Atkinson JT, Heidari H, Losada N, Kim JD, Koder RL, Lu Y, Silberg JJ, Slusky JSG, Falkowski PG, Nanda V. The energetics and evolution of oxidoreductases in deep time. Proteins 2024; 92:52-59. [PMID: 37596815 DOI: 10.1002/prot.26563] [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: 05/16/2023] [Accepted: 07/06/2023] [Indexed: 08/20/2023]
Abstract
The core metabolic reactions of life drive electrons through a class of redox protein enzymes, the oxidoreductases. The energetics of electron flow is determined by the redox potentials of organic and inorganic cofactors as tuned by the protein environment. Understanding how protein structure affects oxidation-reduction energetics is crucial for studying metabolism, creating bioelectronic systems, and tracing the history of biological energy utilization on Earth. We constructed ProtReDox (https://protein-redox-potential.web.app), a manually curated database of experimentally determined redox potentials. With over 500 measurements, we can begin to identify how proteins modulate oxidation-reduction energetics across the tree of life. By mapping redox potentials onto networks of oxidoreductase fold evolution, we can infer the evolution of electron transfer energetics over deep time. ProtReDox is designed to include user-contributed submissions with the intention of making it a valuable resource for researchers in this field.
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Affiliation(s)
- Kenneth N McGuinness
- Department of Natural Sciences, Caldwell University, Caldwell, New Jersey, USA
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - Nolan Fehon
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Ryan Feehan
- Computational Biology Program, The University of Kansas, Lawrence, Kansas, USA
| | - Michelle Miller
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Andrew C Mutter
- Department of Physics, The City College of New York, New York, New York, USA
| | - Laryssa A Rybak
- Department of Physics, The City College of New York, New York, New York, USA
| | - Justin Nam
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - Jenna E AbuSalim
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - Joshua T Atkinson
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Hirbod Heidari
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Natalie Losada
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - J Dongun Kim
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Ronald L Koder
- Department of Physics, The City College of New York, New York, New York, USA
| | - Yi Lu
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Jonathan J Silberg
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Joanna S G Slusky
- Computational Biology Program, The University of Kansas, Lawrence, Kansas, USA
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Vikas Nanda
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
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6
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Wang JX, Vilbert AC, Cui C, Mirts EN, Williams LH, Kim W, Jessie Zhang Y, Lu Y. Increasing Reduction Potentials of Type 1 Copper Center and Catalytic Efficiency of Small Laccase from Streptomyces coelicolor through Secondary Coordination Sphere Mutations. Angew Chem Int Ed Engl 2023; 62:e202314019. [PMID: 37926680 PMCID: PMC10842694 DOI: 10.1002/anie.202314019] [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: 09/19/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
The key to type 1 copper (T1Cu) function lies in the fine tuning of the CuII/I reduction potential (E°'T1Cu ) to match those of its redox partners, enabling efficient electron transfer in a wide range of biological systems. While the secondary coordination sphere (SCS) effects have been used to tune E°'T1Cu in azurin over a wide range, these principles are yet to be generalized to other T1Cu-containing proteins to tune catalytic properties. To this end, we have examined the effects of Y229F, V290N and S292F mutations around the T1Cu of small laccase (SLAC) from Streptomyces coelicolor to match the high E°'T1Cu of fungal laccases. Using ultraviolet-visible absorption and electron paramagnetic resonance spectroscopies, together with X-ray crystallography and redox titrations, we have probed the influence of SCS mutations on the T1Cu and corresponding E°'T1Cu . While minimal and small E°'T1Cu increases are observed in Y229F- and S292F-SLAC, the V290N mutant exhibits a major E°'T1Cu increase. Moreover, the influence of these mutations on E°'T1Cu is additive, culminating in a triple mutant Y229F/V290N/S292F-SLAC with the highest E°'T1Cu of 556 mV vs. SHE reported to date. Further activity assays indicate that all mutants retain oxygen reduction reaction activity, and display improved catalytic efficiencies (kcat /KM ) relative to WT-SLAC.
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Affiliation(s)
- Jing-Xiang Wang
- Department of Chemistry, The University of Texas at Austin, 105 East 24th Street, Austin, TX 78712, USA
| | - Avery C Vilbert
- Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99354, USA
| | - Chang Cui
- Department of Chemistry, The University of Illinois at Urbana-Champaign, 600 South Matthews Avenue, Urbana, IL 61801, USA
| | - Evan N Mirts
- Department of Chemistry, The University of Illinois at Urbana-Champaign, 600 South Matthews Avenue, Urbana, IL 61801, USA
| | - Lucas H Williams
- Department of Molecular Biosciences, The University of Texas at Austin, 100 East 24th St., Austin, TX 78712, USA
| | - Wantae Kim
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Austin, TX 78712, USA
| | - Y Jessie Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, 100 East 24th St., Austin, TX 78712, USA
- Interdisciplinary Life Sciences Graduate Programs, The University of Texas at Austin, 100 East 24th St., Austin, TX 78712, USA
| | - Yi Lu
- Department of Chemistry, The University of Texas at Austin, 105 East 24th Street, Austin, TX 78712, USA
- Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99354, USA
- Department of Chemistry, The University of Illinois at Urbana-Champaign, 600 South Matthews Avenue, Urbana, IL 61801, USA
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Austin, TX 78712, USA
- Interdisciplinary Life Sciences Graduate Programs, The University of Texas at Austin, 100 East 24th St., Austin, TX 78712, USA
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7
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Marciesky M, Aga DS, Bradley IM, Aich N, Ng C. Mechanisms and Opportunities for Rational In Silico Design of Enzymes to Degrade Per- and Polyfluoroalkyl Substances (PFAS). J Chem Inf Model 2023; 63:7299-7319. [PMID: 37981739 PMCID: PMC10716909 DOI: 10.1021/acs.jcim.3c01303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 11/21/2023]
Abstract
Per and polyfluoroalkyl substances (PFAS) present a unique challenge to remediation techniques because their strong carbon-fluorine bonds make them difficult to degrade. This review explores the use of in silico enzymatic design as a potential PFAS degradation technique. The scope of the enzymes included is based on currently known PFAS degradation techniques, including chemical redox systems that have been studied for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) defluorination, such as those that incorporate hydrated electrons, sulfate, peroxide, and metal catalysts. Bioremediation techniques are also discussed, namely the laccase and horseradish peroxidase systems. The redox potential of known reactants and enzymatic radicals/metal-complexes are then considered and compared to potential enzymes for degrading PFAS. The molecular structure and reaction cycle of prospective enzymes are explored. Current knowledge and techniques of enzyme design, particularly radical-generating enzymes, and application are also discussed. Finally, potential routes for bioengineering enzymes to enable or enhance PFAS remediation are considered as well as the future outlook for computational exploration of enzymatic in situ bioremediation routes for these highly persistent and globally distributed contaminants.
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Affiliation(s)
- Melissa Marciesky
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
| | - Diana S Aga
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260, United States
| | - Ian M Bradley
- Department of Civil, Structural, and Environmental Engineering, State University of New York at Buffalo, Buffalo, New York 14228, United States
- Research and Education in Energy, Environmental and Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Nirupam Aich
- Department of Civil and Environmental Engineering, University of Nebraska─Lincoln, Lincoln, Nebraska 68588-0531, United States
| | - Carla Ng
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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8
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Li X, Ratschow AD, Hardt S, Butt HJ. Surface Charge Deposition by Moving Drops Reduces Contact Angles. PHYSICAL REVIEW LETTERS 2023; 131:228201. [PMID: 38101382 DOI: 10.1103/physrevlett.131.228201] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 10/19/2023] [Indexed: 12/17/2023]
Abstract
Slide electrification-the spontaneous charge separation by sliding aqueous drops-can lead to an electrostatic potential in the order of 1 kV and change drop motion substantially. To find out how slide electrification influences the contact angles of moving drops, we analyzed the dynamic contact angles of aqueous drops sliding down tilted plates with insulated surfaces, grounded surfaces, and while grounding the drop. The observed decrease in dynamic contact angles at different salt concentrations is attributed to two effects: An electrocapillary reduction of contact angles caused by drop charging and a change in the free surface energy of the solid due to surface charging.
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Affiliation(s)
- Xiaomei Li
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Aaron D Ratschow
- Institute for Nano- and Microfluidics, TU Darmstadt, Peter-Grünberg-Str. 10, D-64289 Darmstadt, Germany
| | - Steffen Hardt
- Institute for Nano- and Microfluidics, TU Darmstadt, Peter-Grünberg-Str. 10, D-64289 Darmstadt, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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9
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Liu Y, Harnden KA, Van Stappen C, Dikanov SA, Lu Y. A designed Copper Histidine-brace enzyme for oxidative depolymerization of polysaccharides as a model of lytic polysaccharide monooxygenase. Proc Natl Acad Sci U S A 2023; 120:e2308286120. [PMID: 37844252 PMCID: PMC10614608 DOI: 10.1073/pnas.2308286120] [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: 05/19/2023] [Accepted: 09/03/2023] [Indexed: 10/18/2023] Open
Abstract
The "Histidine-brace" (His-brace) copper-binding site, composed of Cu(His)2 with a backbone amine, is found in metalloproteins with diverse functions. A primary example is lytic polysaccharide monooxygenase (LPMO), a class of enzymes that catalyze the oxidative depolymerization of polysaccharides, providing not only an energy source for native microorganisms but also a route to more effective industrial biomass conversion. Despite its importance, how the Cu His-brace site performs this unique and challenging oxidative depolymerization reaction remains to be understood. To answer this question, we have designed a biosynthetic model of LPMO by incorporating the Cu His-brace motif into azurin, an electron transfer protein. Spectroscopic studies, including ultraviolet-visible (UV-Vis) absorption and electron paramagnetic resonance, confirm copper binding at the designed His-brace site. Moreover, the designed protein is catalytically active towards both cellulose and starch, the native substrates of LPMO, generating degraded oligosaccharides with multiturnovers by C1 oxidation. It also performs oxidative cleavage of the model substrate 4-nitrophenyl-D-glucopyranoside, achieving a turnover number ~9% of that of a native LPMO assayed under identical conditions. This work presents a rationally designed artificial metalloenzyme that acts as a structural and functional mimic of LPMO, which provides a promising system for understanding the role of the Cu His-brace site in LPMO activity and potential application in polysaccharide degradation.
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Affiliation(s)
- Yiwei Liu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
- Department of Chemistry, University of Texas at Austin, Austin, TX78712
| | - Kevin A. Harnden
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Casey Van Stappen
- Department of Chemistry, University of Texas at Austin, Austin, TX78712
| | - Sergei A. Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
- Department of Chemistry, University of Texas at Austin, Austin, TX78712
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10
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Cáceres JC, Dolmatch A, Greene BL. The Mechanism of Inhibition of Pyruvate Formate Lyase by Methacrylate. J Am Chem Soc 2023; 145:22504-22515. [PMID: 37797332 PMCID: PMC10591478 DOI: 10.1021/jacs.3c07256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Indexed: 10/07/2023]
Abstract
Pyruvate Formate Lyase (PFL) catalyzes acetyl transfer from pyruvate to coenzyme a by a mechanism involving multiple amino acid radicals. A post-translationally installed glycyl radical (G734· in Escherichia coli) is essential for enzyme activity and two cysteines (C418 and C419) are proposed to form thiyl radicals during turnover, yet their unique roles in catalysis have not been directly demonstrated with both structural and electronic resolution. Methacrylate is an isostructural analog of pyruvate and an informative irreversible inhibitor of pfl. Here we demonstrate the mechanism of inhibition of pfl by methacrylate. Treatment of activated pfl with methacrylate results in the conversion of the G734· to a new radical species, concomitant with enzyme inhibition, centered at g = 2.0033. Spectral simulations, reactions with methacrylate isotopologues, and Density Functional Theory (DFT) calculations support our assignment of the radical to a C2 tertiary methacryl radical. The reaction is specific for C418, as evidenced by mass spectrometry. The methacryl radical decays over time, reforming G734·, and the decay exhibits a H/D solvent isotope effect of 3.4, consistent with H-atom transfer from an ionizable donor, presumably the C419 sulfhydryl group. Acrylate also inhibits PFL irreversibly, and alkylates C418, but we did not observe an acryl secondary radical in H2O or in D2O within 10 s, consistent with our DFT calculations and the expected reactivity of a secondary versus tertiary carbon-centered radical. Together, the results support unique roles of the two active site cysteines of PFL and a C419 S-H bond dissociation energy between that of a secondary and tertiary C-H bond.
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Affiliation(s)
- Juan Carlos Cáceres
- Biomolecular
Science and Engineering Program, University
of California, Santa
Barbara, California 93106, United States
| | - August Dolmatch
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Brandon L. Greene
- Biomolecular
Science and Engineering Program, University
of California, Santa
Barbara, California 93106, United States
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
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11
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Van Stappen C, Dai H, Jose A, Tian S, Solomon EI, Lu Y. Primary and Secondary Coordination Sphere Effects on the Structure and Function of S-Nitrosylating Azurin. J Am Chem Soc 2023; 145:20610-20623. [PMID: 37696009 PMCID: PMC10539042 DOI: 10.1021/jacs.3c07399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Much progress has been made in understanding the roles of the secondary coordination sphere (SCS) in tuning redox potentials of metalloproteins. In contrast, the impact of SCS on reactivity is much less understood. A primary example is how copper proteins can promote S-nitrosylation (SNO), which is one of the most important dynamic post-translational modifications, and is crucial in regulating nitric oxide storage and transportation. Specifically, the factors that instill CuII with S-nitrosylating capabilities and modulate activity are not well understood. To address this issue, we investigated the influence of the primary and secondary coordination sphere on CuII-catalyzed S-nitrosylation by developing a series of azurin variants with varying catalytic capabilities. We have employed a multidimensional approach involving electronic absorption, S and Cu K-edge XAS, EPR, and resonance Raman spectroscopies together with QM/MM computational analysis to examine the relationships between structure and molecular mechanism in this reaction. Our findings have revealed that kinetic competency is correlated with three balancing factors, namely Cu-S bond strength, Cu spin localization, and relative S(ps) vs S(pp) contributions to the ground state. Together, these results support a reaction pathway that proceeds through the attack of the Cu-S bond rather than electrophilic addition to CuII or radical attack of SCys. The insights gained from this work provide not only a deeper understanding of SNO in biology but also a basis for designing artificial and tunable SNO enzymes to regulate NO and prevent diseases due to SNO dysregulation.
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Affiliation(s)
- Casey Van Stappen
- Department of Chemistry, University of Texas at Austin, 105 E 24th St., Austin, Texas 78712, United States
| | - Huiguang Dai
- Department of Chemistry, University of Texas at Austin, 105 E 24th St., Austin, Texas 78712, United States
- Department of Chemistry, University of Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Shiliang Tian
- Department of Chemistry, University of Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yi Lu
- Department of Chemistry, University of Texas at Austin, 105 E 24th St., Austin, Texas 78712, United States
- Department of Chemistry, University of Urbana-Champaign, Champaign, Illinois 61801, United States
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12
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Koone J, Simmang M, Saenger DL, Hunsicker-Wang LM, Shaw BF. Charge Regulation in a Rieske Proton Pump Pinpoints Zero, One, and Two Proton-Coupled Electron Transfer. J Am Chem Soc 2023; 145:16488-16497. [PMID: 37486967 PMCID: PMC10402712 DOI: 10.1021/jacs.3c03006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Indexed: 07/26/2023]
Abstract
The degree to which redox-driven proton pumps regulate net charge during electron transfer (ΔZET) remains undetermined due to difficulties in measuring the net charge of solvated proteins. Values of ΔZET can reflect reorganization energies or redox potentials associated with ET and can be used to distinguish ET from proton(s)-coupled electron transfer (PCET). Here, we synthesized protein "charge ladders" of a Rieske [2Fe-2S] subunit from Thermus thermophilus (truncTtRp) and made 120 electrostatic measurements of ΔZET across pH. Across pH 5-10, truncTtRp is suspected of transitioning from ET to PCET, and then to two proton-coupled ET (2PCET). Upon reduction, we found that truncTtRp became more negative at pH 6.0 by one unit (ΔZET = -1.01 ± 0.14), consistent with single ET; was isoelectric at pH 8.8 (ΔZET = -0.01 ± 0.45), consistent with PCET; and became more positive at pH 10.6 (ΔZET = +1.37 ± 0.60), consistent with 2PCET. These ΔZET values are attributed to protonation of H154 and H134. Across pH, redox potentials of TtRp (measured previously) correlated with protonation energies of H154 and H134 and ΔZET for truncTtRp, supporting a discrete proton pumping mechanism for Rieske proteins at the Fe-coordinating histidines.
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Affiliation(s)
- Jordan
C. Koone
- Department
of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
| | - Mikaela Simmang
- Department
of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Devin L. Saenger
- Department
of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | | | - Bryan F. Shaw
- Department
of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
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13
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Lin YC, Ren P, Webb LJ. AMOEBA Force Field Predicts Accurate Hydrogen Bond Counts of Nitriles in SNase by Revealing Water-Protein Interaction in Vibrational Absorption Frequencies. J Phys Chem B 2023; 127:5609-5619. [PMID: 37339399 PMCID: PMC10851345 DOI: 10.1021/acs.jpcb.3c02060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Precisely quantifying the magnitude and direction of electric fields in proteins has long been an outstanding challenge in understanding biological functions. Nitrile vibrational Stark effect probes have been shown to be minimally disruptive to the protein structure and can be better direct reporters of local electrostatic field in the native state of a protein than other measures such as pKa shifts of titratable residues. However, interpretations of the connection between measured vibrational energy and electric field rely on the accurate molecular understanding of interactions of the nitrile group and its environment, particularly from hydrogen bonding. In this work, we compared the extent of hydrogen bonding calculated in two common force fields, the fixed charge force field Amber03 and polarizable force field AMOEBA, at 10 locations of cyanocysteine (CNC) in staphylococcal nuclease (SNase) against the experimental nitrile absorption frequency in terms of full width at half-maximum (FWHM) and frequency temperature line slope (FTLS). We observed that the number of hydrogen bonds correlated well in AMOEBA trajectories with respect to both the FWHM (r = 0.88) and the FTLS (r = -0.85), whereas the correlation of Amber03 trajectories was less reliable because the Amber03 force field predicted more hydrogen bonds in some mutants. Moreover, we demonstrated that contributions from the interactions between CNC and nearby water molecules were significant in AMOEBA trajectories but were not predicted by Amber03. We conclude that although the nitrile absorption peak shape could be qualitatively predicted by the fixed charge Amber03 force field, the detailed electrostatic environment measured by the nitrile probe in terms of the extent of hydrogen bonding could only be accurately observed in the AMOEBA trajectories, where the permanent dipole, quadrupole, and dipole-induced-dipole polarizable interactions were all taken into account. The significance of this finding to the goal of accurately predicting electric fields in complex biomolecular environments is discussed.
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Affiliation(s)
- Yu-Chun Lin
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX, 78712, USA
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Lauren J. Webb
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX, 78712, USA
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14
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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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15
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Smithwick ER, Wilson RH, Chatterjee S, Pu Y, Dalluge JJ, Damodaran AR, Bhagi-Damodaran A. Electrostatically regulated active site assembly governs reactivity in non-heme iron halogenases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542349. [PMID: 37292651 PMCID: PMC10245910 DOI: 10.1101/2023.05.25.542349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Non-heme iron halogenases (NHFe-Hals) catalyze the direct insertion of a chloride/bromide ion at an unactivated carbon position using a high-valent haloferryl intermediate. Despite more than a decade of structural and mechanistic characterization, how NHFe-Hals preferentially bind specific anions and substrates for C-H functionalization remains unknown. Herein, using lysine halogenating BesD and HalB enzymes as model systems, we demonstrate strong positive cooperativity between anion and substrate binding to the catalytic pocket. Detailed computational investigations indicate that a negatively charged glutamate hydrogen-bonded to iron's equatorial-aqua ligand acts as an electrostatic lock preventing both lysine and anion binding in the absence of the other. Using a combination of UV-Vis spectroscopy, binding affinity studies, stopped-flow kinetics investigations, and biochemical assays, we explore the implication of such active site assembly towards chlorination, bromination, and azidation reactivities. Overall, our work highlights previously unknown features regarding how anion-substrate pair binding govern reactivity of iron halogenases that are crucial for engineering next-generation C-H functionalization biocatalysts.
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Affiliation(s)
- Elizabeth R. Smithwick
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - R. Hunter Wilson
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Sourav Chatterjee
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Yu Pu
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Joseph J. Dalluge
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Anoop Rama Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
| | - Ambika Bhagi-Damodaran
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA
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16
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Oostrom M, Akers S, Garrett N, Hanson E, Shaw W, Laureanti JA. Classifying metal-binding sites with neural networks. Protein Sci 2023; 32:e4591. [PMID: 36775934 PMCID: PMC9951193 DOI: 10.1002/pro.4591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 01/30/2023] [Accepted: 02/07/2023] [Indexed: 02/14/2023]
Abstract
To advance our ability to predict impacts of the protein scaffold on catalysis, robust classification schemes to define features of proteins that will influence reactivity are needed. One of these features is a protein's metal-binding ability, as metals are critical to catalytic conversion by metalloenzymes. As a step toward realizing this goal, we used convolutional neural networks (CNNs) to enable the classification of a metal cofactor binding pocket within a protein scaffold. CNNs enable images to be classified based on multiple levels of detail in the image, from edges and corners to entire objects, and can provide rapid classification. First, six CNN models were fine-tuned to classify the 20 standard amino acids to choose a performant model for amino acid classification. This model was then trained in two parallel efforts: to classify a 2D image of the environment within a given radius of the central metal binding site, either an Fe ion or a [2Fe-2S] cofactor, with the metal visible (effort 1) or the metal hidden (effort 2). We further used two sub-classifications of the [2Fe-2S] cofactor: (1) a standard [2Fe-2S] cofactor and (2) a Rieske [2Fe-2S] cofactor. The accuracy for the model correctly identifying all three defined features was >95%, despite our perception of the increased challenge of the metalloenzyme identification. This demonstrates that machine learning methodology to classify and distinguish similar metal-binding sites, even in the absence of a visible cofactor, is indeed possible and offers an additional tool for metal-binding site identification in proteins.
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Affiliation(s)
- Marjolein Oostrom
- National Security Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Sarah Akers
- National Security Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Noah Garrett
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Emma Hanson
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Wendy Shaw
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Joseph A Laureanti
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
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17
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Fatima S, Boggs DG, Ali N, Thompson PJ, Thielges MC, Bridwell-Rabb J, Olshansky L. Engineering a Conformationally Switchable Artificial Metalloprotein. J Am Chem Soc 2022; 144:21606-21616. [DOI: 10.1021/jacs.2c08885] [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]
Affiliation(s)
- Saman Fatima
- Department of Chemistry, University of Illinois Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois61801, United States
| | - David G. Boggs
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan48109, United States
| | - Noor Ali
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana47405, United States
| | - Peter J. Thompson
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois61801, United States
| | - Megan C. Thielges
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana47405, United States
| | - Jennifer Bridwell-Rabb
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan48109, United States
| | - Lisa Olshansky
- Department of Chemistry, University of Illinois Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois61801, United States
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois61801, United States
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18
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Lin YC, Ren P, Webb LJ. AMOEBA Force Field Trajectories Improve Predictions of Accurate p Ka Values of the GFP Fluorophore: The Importance of Polarizability and Water Interactions. J Phys Chem B 2022; 126:7806-7817. [PMID: 36194474 PMCID: PMC10851343 DOI: 10.1021/acs.jpcb.2c03642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Precisely quantifying the magnitude, direction, and biological functions of electric fields in proteins has long been an outstanding challenge in the field. The most widely implemented experimental method to measure such electric fields at a particular residue in a protein has been through changes in pKa of titratable residues. While many computational strategies exist to predict these values, it has been difficult to do this accurately or connect predicted results to key structural or mechanistic features of the molecule. Here, we used experimentally determined pKa values of the fluorophore in superfolder green fluorescent protein (GFP) with amino acid mutations made at position Thr 203 to evaluate the pKa prediction ability of molecular dynamics (MD) simulations using a polarizable force field, AMOEBA. Structure ensembles from AMOEBA were used to calculate pKa values of the GFP fluorophore. The calculated pKa values were then compared to trajectories using a conventional fixed charge force field (Amber03 ff). We found that the position of water molecules included in the pKa calculation had opposite effects on the pKa values between the trajectories from AMOEBA and Amber03 force fields. In AMOEBA trajectories, the inclusion of water molecules within 35 Å of the fluorophore decreased the difference between the predicted and experimental values, resulting in calculated pKa values that were within an average of 0.8 pKa unit from the experimental results. On the other hand, in Amber03 trajectories, including water molecules that were more than 5 Å from the fluorophore increased the differences between the calculated and experimental pKa values. The inaccuracy of pKa predictions determined from Amber03 trajectories was caused by a significant stabilization of the deprotonated chromophore's free energy compared to the result in AMOEBA. We rationalize the cutoffs for explicit water molecules when calculating pKa to better predict the electrostatic environment surrounding the fluorophore buried in GFP. We discuss how the results from this work will assist the prospective prediction of pKa values or other electrostatic effects in a wide variety of folded proteins.
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Affiliation(s)
- Yu-Chun Lin
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX 78712-1224
| | - Pengyu Ren
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX 78712-1224
| | - Lauren J. Webb
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX 78712-1224
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19
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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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20
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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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21
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Gibbs CA, Fedoretz-Maxwell BP, Warren JJ. On the roles of methionine and the importance of its microenvironments in redox metalloproteins. Dalton Trans 2022; 51:4976-4985. [PMID: 35253809 DOI: 10.1039/d1dt04387k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The amino acid residue methionine (Met) is commonly thought of as a ligand in redox metalloproteins, for example in cytochromes c and in blue copper proteins. However, the roles of Met can go beyond a simple ligand. The thioether functional group of Met allows it to be considered as a hydrophobic residue as well as one that is capable of weak dipolar interactions. In addition, the lone pairs on sulphur allow Met to interact with other groups, inluding the aforementioned metal ions. Because of its properties, Met can play diverse roles in metal coordination, fine tuning of redox reactions, or supporting protein structures. These roles are strongly influenced by the nature of the surrounding medium. Herein, we describe several common interactions between Met and surrounding aromatic amino acids and how they affect the physical properties of both copper and iron metalloproteins. While the importance of interactions between Met and other groups is established in biological systems, less is known about their roles in redox metalloproteins and our view is that this is an area that is ready for greater attention.
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Affiliation(s)
- Curtis A Gibbs
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada.
| | | | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada.
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22
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Electrochemical Characterization of an Engineered Red Copper Protein Featuring an Unprecedented Entropic Control of the Reduction Potential. Bioelectrochemistry 2022; 146:108095. [DOI: 10.1016/j.bioelechem.2022.108095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/04/2022] [Accepted: 03/10/2022] [Indexed: 12/12/2022]
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23
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Heghmanns M, Günzel A, Brandis D, Kutin Y, Engelbrecht V, Winkler M, Happe T, Kasanmascheff M. Fine-tuning of FeS proteins monitored via pulsed EPR redox potentiometry at Q-band. BIOPHYSICAL REPORTS 2021; 1:100016. [PMID: 36425453 PMCID: PMC9680799 DOI: 10.1016/j.bpr.2021.100016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/30/2021] [Indexed: 06/16/2023]
Abstract
As essential electron translocating proteins in photosynthetic organisms, multiple plant-type ferredoxin (Fdx) isoforms are involved in a high number of reductive metabolic processes in the chloroplast. To allow quick cellular responses under changing environmental conditions, different plant-type Fdxs in Chlamydomonas reinhardtii were suggested to have adapted their midpoint potentials to a wide range of interaction partners. We performed pulsed electron paramagnetic resonance (EPR) monitored redox potentiometry at Q-band on three Fdx isoforms for a straightforward determination of their midpoint potentials. Additionally, site-directed mutagenesis was used to tune the midpoint potential of CrFdx1 in a range of approximately -338 to -511 mV, confirming the importance of single positions in the protein environment surrounding the [2Fe2S] cluster. Our results present a new target for future studies aiming to modify the catalytic activity of CrFdx1 that plays an essential role either as electron acceptor of photosystem I or as electron donor to hydrogenases under certain conditions. Additionally, the precisely determined redox potentials in this work using pulsed EPR demonstrate an alternative method that provides additional advantages compared with the well-established continuous wave EPR technique.
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Affiliation(s)
- Melanie Heghmanns
- TU Dortmund University, Department of Chemistry and Chemical Biology, Dortmund, Germany
| | - Alexander Günzel
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Photobiotechnology, Bochum, Germany
| | - Dörte Brandis
- TU Dortmund University, Department of Chemistry and Chemical Biology, Dortmund, Germany
| | - Yury Kutin
- TU Dortmund University, Department of Chemistry and Chemical Biology, Dortmund, Germany
| | - Vera Engelbrecht
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Photobiotechnology, Bochum, Germany
| | - Martin Winkler
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Photobiotechnology, Bochum, Germany
| | - Thomas Happe
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Photobiotechnology, Bochum, Germany
| | - Müge Kasanmascheff
- TU Dortmund University, Department of Chemistry and Chemical Biology, Dortmund, Germany
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24
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Vilbert AC, Liu Y, Dai H, Lu Y. Recent advances in tuning redox properties of electron transfer centers in metalloenzymes catalyzing oxygen reduction reaction and H 2 oxidation important for fuel cells design. CURRENT OPINION IN ELECTROCHEMISTRY 2021; 30:100780. [PMID: 34435160 PMCID: PMC8382256 DOI: 10.1016/j.coelec.2021.100780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Current fuel-cell catalysts for oxygen reduction reaction (ORR) and H2 oxidation use precious metals and, for ORR, require high overpotentials. In contrast, metalloenzymes perform their respective reaction at low overpotentials using earth-abundant metals, making metalloenzymes ideal candidates for inspiring electrocatalytic design. Critical to the success of these enzymes are redox-active metal centers surrounding the enzyme active sites that ensure fast electron transfer (ET) to or away from the active site, by tuning the catalytic potential of the reaction as observed in multicopper oxidases but also in dictating the catalytic bias of the reaction as realized in hydrogenases. This review summarizes recent advances in studying these ET centers in multicopper oxidases and heme-copper oxidases that perform ORR and hydrogenases in carrying out H2 oxidation. Insights gained from understanding how the reduction potential of the ET centers effects reactivity at the active site in both the enzymes and their models are provided.
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Affiliation(s)
| | - Yiwei Liu
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Huiguang Dai
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yi Lu
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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25
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Buades AB, Viñas C, Fontrodona X, Teixidor F. 1.3 V Inorganic Sequential Redox Chain with an All-Anionic Couple 1-/2- in a Single Framework. Inorg Chem 2021; 60:16168-16177. [PMID: 34693711 PMCID: PMC9180739 DOI: 10.1021/acs.inorgchem.1c01822] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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The relatively low symmetry of [3,3′-Co(1,2-C2B9H11)2]− ([1]−), along with the high number
of available
substitution sites, 18 on the boron atoms and 4 on the carbon atoms,
allows a fairly regioselective and stepwise chlorination of the platform
and therefore a very controlled tuning of the electrochemical potential
tuning. This is not so easily found in other systems, e.g., ferrocene.
In this work, we show how a single platform with boron and carbon
in the ligand, and only cobalt can produce a tuning of potentials
in a stepwise manner in the 1.3 V range. The platform used is made
of two icosahedra sharing one vertex. The E1/2 tuning has been achieved from [1]− by sequential chlorination, which has given potentials whose values
increase sequentially and linearly with the number of chloro groups
in the platform. [Cl8-1]−, [Cl10-1]−, and [Cl12-1]− have been obtained, which
are added to the existing [Cl-1]−,
[Cl2-1]−, [Cl4-1]−, and [Cl6-1]− described earlier to give the 1.3 V range. It is envisaged
to extend this range also sequentially by changing the metal from
cobalt to iron. The last successful synthesis of the highest chlorinated
derivatives of cobaltabis(dicarbollide) dates back to 1982, and since
then, no more advances have occurred toward more substituted metallacarborane
chlorinated compounds. [Cl8-1]−, [Cl10-1]−, and [Cl12-1]− are made
with an easy and fast method. The key point of the reaction is the
use of the protonated form of [Co(C2B9H11)2]−, as a starting material,
and the use of sulfuryl chloride, a less hazardous and easier to use
chlorinating agent. In addition, we present a complete, spectroscopic,
crystallographic, and electrochemical characterization, together with
a study of the influence of the chlorination position in the electrochemical
properties. By sequential halogenation of [Co(C2B9H11)2]− ([1]−) with chlorine, the [Cl8-1]−, [Cl10-1]−, and [Cl12-1]− derivatives
of [1]− have been prepared and isolated.
The E1/2 values increase sequentially
and linearly with the number of chloro groups in the platform. If
these potentials are added to the existing E1/2 values due to [Cl-1]−, [Cl2-1]−, [Cl4-1]−, and [Cl6-1]− described earlier, a 1.3 V range is obtained. This
allows tuning of the desired potentials for the purposes of nature.
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Affiliation(s)
- Ana B Buades
- Institut de Ciència de Materials de Barcelona, Consejo Superior de Investigaciones Científicas, Campus Universitat Autonòma de Barcelona (UAB), 08193 Bellaterra, Spain
| | - Clara Viñas
- Institut de Ciència de Materials de Barcelona, Consejo Superior de Investigaciones Científicas, Campus Universitat Autonòma de Barcelona (UAB), 08193 Bellaterra, Spain
| | - Xavier Fontrodona
- Departamento de Química and Serveis Tècnics de Recerca, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain
| | - Francesc Teixidor
- Institut de Ciència de Materials de Barcelona, Consejo Superior de Investigaciones Científicas, Campus Universitat Autonòma de Barcelona (UAB), 08193 Bellaterra, Spain
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26
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Harnden KA, Roy A, Hosseinzadeh P. Overview of Methods for Purification and Characterization of Metalloproteins. Curr Protoc 2021; 1:e234. [PMID: 34436821 DOI: 10.1002/cpz1.234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metalloproteins make up one third of all proteins and perform some of the most essential reactions on earth. The unique properties of the metal ions within these proteins, and in particular of redox-active metal ions, enables the use of a number of characterization techniques. It also necessitates unique considerations in terms of purification and characterization. In this overview, we describe the considerations and methods used for metalloprotein purification and characterization. © 2021 Wiley Periodicals LLC.
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Affiliation(s)
| | - Anindya Roy
- University of Washington, Department of Biochemistry, Institute for Protein Design, Seattle, Washington
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27
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Klein AS, Zeymer C. Design and engineering of artificial metalloproteins: from de novo metal coordination to catalysis. Protein Eng Des Sel 2021; 34:6150309. [PMID: 33635315 DOI: 10.1093/protein/gzab003] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 11/13/2022] Open
Abstract
Metalloproteins are essential to sustain life. Natural evolution optimized them for intricate structural, regulatory and catalytic functions that cannot be fulfilled by either a protein or a metal ion alone. In order to understand this synergy and the complex design principles behind the natural systems, simpler mimics were engineered from the bottom up by installing de novo metal sites in either natural or fully designed, artificial protein scaffolds. This review focuses on key challenges associated with this approach. We discuss how proteins can be equipped with binding sites that provide an optimal coordination environment for a metal cofactor of choice, which can be a single metal ion or a complex multinuclear cluster. Furthermore, we highlight recent studies in which artificial metalloproteins were engineered towards new functions, including electron transfer and catalysis. In this context, the powerful combination of de novo protein design and directed evolution is emphasized for metalloenzyme development.
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Affiliation(s)
- Andreas S Klein
- Department of Chemistry, Technische Universität München, 85747 Garching, Germany
| | - Cathleen Zeymer
- Department of Chemistry, Technische Universität München, 85747 Garching, Germany
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28
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Han H, Zheng Y, Zhou T, Liu P, Li X. Cu(II) nonspecifically binding chromate reductase NfoR promotes Cr(VI) reduction. Environ Microbiol 2020; 23:415-430. [PMID: 33201569 DOI: 10.1111/1462-2920.15329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/30/2020] [Accepted: 11/15/2020] [Indexed: 11/26/2022]
Abstract
Cu(II)-enhanced microbial Cr(VI) reduction is common in the environment, yet its mechanism is unknown. The specific activity of chromate reductase, NfoR, from Staphylococcus aureus sp. LZ-01 was augmented 1.5-fold by Cu(II). Isothermal titration calorimetry and spectral data show that Cu(II) binds to NfoR nonspecifically. Further, Cu(II) stimulates the nitrobenzene reduction of NfoR, indicating that Cu(II) promotes electron transfer. The crystal structure of NfoR in complex with CuSO4 (1.46 Å) was determined. The overall structure of NfoR-Cu(II) complex is a dimer that covalently binds with FMN and Cu(II)-binding pocket is located at the interface of the NfoR dimer. Structural superposition revealed that NfoR resembles the structure of class II chromate reductase. Site-directed mutagenesis revealed that Leu46 and Phe123 were involved in NADH binding, whereas Trp70 and Ser45 were the key residues for nitrobenzene binding. Furthermore, His100 and Asp171 were preferential affinity sites for Cu(II) and that Cys163 is an active site for FMN binding. Attenuation reductase activity in C163S can be partially restored to 54% wild type by increasing Cu(II) concentration. Partial restoration indicates dual-channel electron transfer of NfoR via Cu(II) and FMN. We propose a catalytic mechanism for Cu(II)-enhanced NfoR activity in which Cu(I) is formed transiently. Together, the current results provide an insight on Cu (II)-induced enhancement and benefit of Cr(VI) bioremediation.
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Affiliation(s)
- Huawen Han
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Yuanzhang Zheng
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, USA
| | - Tuoyu Zhou
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Pu Liu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
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29
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Mirts EN, Dikanov SA, Jose A, Solomon EI, Lu Y. A Binuclear Cu A Center Designed in an All α-Helical Protein Scaffold. J Am Chem Soc 2020; 142:13779-13794. [PMID: 32662996 DOI: 10.1021/jacs.0c04226] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The primary and secondary coordination spheres of metal binding sites in metalloproteins have been investigated extensively, leading to the creation of high-performing functional metalloproteins; however, the impact of the overall structure of the protein scaffold on the unique properties of metalloproteins has rarely been studied. A primary example is the binuclear CuA center, an electron transfer cupredoxin domain of photosynthetic and respiratory complexes and, recently, a protein coregulated with particulate methane and ammonia monooxygenases. The redox potential, Cu-Cu spectroscopic features, and a valence delocalized state of CuA are difficult to reproduce in synthetic models, and every artificial protein CuA center to-date has used a modified cupredoxin. Here, we present a fully functional CuA center designed in a structurally nonhomologous protein, cytochrome c peroxidase (CcP), by only two mutations (CuACcP). We demonstrate with UV-visible absorption, resonance Raman, and magnetic circular dichroism spectroscopy that CuACcP is valence delocalized. Continuous wave and pulsed (HYSCORE) X-band EPR show it has a highly compact gz area and small Az hyperfine principal value with g and A tensors that resemble axially perturbed CuA. Stopped-flow kinetics found that CuA formation proceeds through a single T2Cu intermediate. The reduction potential of CuACcP is comparable to native CuA and can transfer electrons to a physiological redox partner. We built a structural model of the designed Cu binding site from extended X-ray absorption fine structure spectroscopy and validated it by mutation of coordinating Cys and His residues, revealing that a triad of residues (R48C, W51C, and His52) rigidly arranged on one α-helix is responsible for chelating the first Cu(II) and that His175 stabilizes the binuclear complex by rearrangement of the CcP heme-coordinating helix. This design is a demonstration that a highly conserved protein fold is not uniquely necessary to induce certain characteristic physical and chemical properties in a metal redox center.
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Affiliation(s)
- Evan N Mirts
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sergei A Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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30
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Yu SS, Li JJ, Cui C, Tian S, Chen JJ, Yu HQ, Hou C, Nilges MJ, Lu Y. Structural Basis for a Quadratic Relationship between Electronic Absorption and Electronic Paramagnetic Resonance Parameters of Type 1 Copper Proteins. Inorg Chem 2020; 59:10620-10627. [PMID: 32689800 DOI: 10.1021/acs.inorgchem.0c01065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Type 1 copper (T1Cu) proteins play important roles in electron transfer in biology, largely due to the unique structure of the T1Cu center, which is reflected by its spectroscopic properties. Previous reports have suggested a correlation between a high ratio of electronic absorbance at ∼450 nm to that at ∼600 nm (R = A450/A600) and a large copper(II) hyperfine coupling in the z direction (Az) in electron paramagnetic resonance (EPR). However, this correlation does not have a clear physical meaning, nor does it hold for many proteins with a perturbed T1Cu center. To address this issue, a new parameter of R' [A450/(A450 + A600)] with a better physical meaning of a fractional SCys pseudo-σ to Cu(II) charge transfer transition intensity is defined and a quadratic relationship between R' and Az is found on the basis of a comprehensive analysis of ultraviolet-visible absorption, EPR, and structural parameters of T1Cu proteins. We are able to find good correlations between R' and the displacement of copper from the trigonal plane defined by the His2Cys ligands and the angle between the NHis1-Cu-NHis2 plane and the SCys-Cu-axial ligand plane, providing a structural basis for the observed correlation. These findings and analyses provide a new framework for a deeper understanding of the spectroscopic and electronic properties of T1Cu proteins, which may allow better design and applications of this important class of proteins for redox and electron transfer functions.
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Affiliation(s)
- Sheng-Song Yu
- Department of Applied Chemistry, University of Science & Technology of China, Hefei, Anhui 230026, P. R. China.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Jun-Jie Li
- Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Chang Cui
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Jie-Jie Chen
- Department of Applied Chemistry, University of Science & Technology of China, Hefei, Anhui 230026, P. R. China
| | - Han-Qing Yu
- Department of Applied Chemistry, University of Science & Technology of China, Hefei, Anhui 230026, P. R. China
| | - Changjun Hou
- Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China
| | - Mark J Nilges
- School of Chemical Sciences Electron Paramagnetic Resonance Lab, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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31
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Crittenden CM, Novelli ET, Mehaffey MR, Xu GN, Giles DH, Fies WA, Dalby KN, Webb LJ, Brodbelt JS. Structural Evaluation of Protein/Metal Complexes via Native Electrospray Ultraviolet Photodissociation Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1140-1150. [PMID: 32275426 PMCID: PMC7386362 DOI: 10.1021/jasms.0c00066] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Ultraviolet photodissociation (UVPD) has emerged as a promising tool to characterize proteins with regard to not only their primary sequences and post-translational modifications, but also their tertiary structures. In this study, three metal-binding proteins, Staphylococcal nuclease, azurin, and calmodulin, are used to demonstrate the use of UVPD to elucidate metal-binding regions via comparisons between the fragmentation patterns of apo (metal-free) and holo (metal-bound) proteins. The binding of staphylococcal nuclease to calcium was evaluated, in addition to a series of lanthanide(III) ions which are expected to bind in a similar manner as calcium. On the basis of comparative analysis of the UVPD spectra, the binding region for calcium and the lanthanide ions was determined to extend from residues 40-50, aligning with the known crystal structure. Similar analysis was performed for both azurin (interrogating copper and silver binding) and calmodulin (four calcium binding sites). This work demonstrates the utility of UVPD methods for determining and analyzing the metal binding sites of a variety of classes of proteins.
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Affiliation(s)
| | - Elisa T Novelli
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - M Rachel Mehaffey
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Gulan N Xu
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Whitney A Fies
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712, United States
- Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712, United States
| | - Lauren J Webb
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
- Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712, United States
- Texas Materials Institute, University of Texas, Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
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32
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Caserta G, Lorent C, Ciaccafava A, Keck M, Breglia R, Greco C, Limberg C, Hildebrandt P, Cramer SP, Zebger I, Lenz O. The large subunit of the regulatory [NiFe]-hydrogenase from Ralstonia eutropha - a minimal hydrogenase? Chem Sci 2020; 11:5453-5465. [PMID: 34094072 PMCID: PMC8159394 DOI: 10.1039/d0sc01369b] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Chemically synthesized compounds that are capable of facilitating the reversible splitting of dihydrogen into protons and electrons are rare in chemists' portfolio. The corresponding biocatalysts – hydrogenases – are, however, abundant in the microbial world. [NiFe]-hydrogenases represent a major subclass and display a bipartite architecture, composed of a large subunit, hosting the catalytic NiFe(CO)(CN)2 cofactor, and a small subunit whose iron–sulfur clusters are responsible for electron transfer. To analyze in detail the catalytic competence of the large subunit without its smaller counterpart, we purified the large subunit HoxC of the regulatory [NiFe]-hydrogenase of the model H2 oxidizer Ralstonia eutropha to homogeneity. Metal determination and infrared spectroscopy revealed a stoichiometric loading of the metal cofactor. This enabled for the first time the determination of the UV-visible extinction coefficient of the NiFe(CO)(CN)2 cofactor. Moreover, the absence of disturbing iron–sulfur clusters allowed an unbiased look into the low-spin Fe2+ of the active site by Mössbauer spectroscopy. Isolated HoxC was active in catalytic hydrogen–deuterium exchange, demonstrating its capacity to activate H2. Its catalytic activity was drastically lower than that of the bipartite holoenzyme. This was consistent with infrared and electron paramagnetic resonance spectroscopic observations, suggesting that the bridging position between the active site nickel and iron ions is predominantly occupied by water-derived ligands, even under reducing conditions. In fact, the presence of water-derived ligands bound to low-spin Ni2+ was reflected by the absorption bands occurring in the corresponding UV-vis spectra, as revealed by time-dependent density functional theory calculations conducted on appropriate in silico models. Thus, the isolated large subunits indeed represent simple [NiFe]-hydrogenase models, which could serve as blueprints for chemically synthesized mimics. Furthermore, our data point to a fundamental role of the small subunit in preventing water access to the catalytic center, which significantly increases the H2 splitting capacity of the enzyme. Spectroscopic investigation of an isolated [NiFe]-hydrogenase large subunit enables a unique view of the NiFe(CO)(CN)2 cofactor.![]()
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Affiliation(s)
- Giorgio Caserta
- Institut für Chemie, Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Christian Lorent
- Institut für Chemie, Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Alexandre Ciaccafava
- Institut für Chemie, Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Matthias Keck
- Department of Chemistry, Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - Raffaella Breglia
- Department of Earth and Environmental Sciences, Milano-Bicocca University Piazza della Scienza 1 20126 Milan Italy
| | - Claudio Greco
- Department of Earth and Environmental Sciences, Milano-Bicocca University Piazza della Scienza 1 20126 Milan Italy
| | - Christian Limberg
- Department of Chemistry, Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | | | - Ingo Zebger
- Institut für Chemie, Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Oliver Lenz
- Institut für Chemie, Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
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33
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Laureanti JA, Ginovska B, Buchko GW, Schenter GK, Hebert M, Zadvornyy OA, Peters JW, Shaw WJ. A Positive Charge in the Outer Coordination Sphere of an Artificial Enzyme Increases CO2 Hydrogenation. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00843] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joseph A. Laureanti
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Bojana Ginovska
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Garry W. Buchko
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, United States
| | - Gregory K. Schenter
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Margaret Hebert
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Oleg A. Zadvornyy
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - John W. Peters
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - Wendy J. Shaw
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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34
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Valles M, Kamaruddin AF, Wong LS, Blanford CF. Inhibition in multicopper oxidases: a critical review. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00724b] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This review critiques the literature on inhibition of O2-reduction catalysis in multicopper oxidases like laccase and bilirubin oxidase and provide recommendations for best practice when carrying out experiments and interpreting published data.
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Affiliation(s)
- Morgane Valles
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
- Department of Chemistry
| | - Amirah F. Kamaruddin
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
- Department of Materials
| | - Lu Shin Wong
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
- Department of Chemistry
| | - Christopher F. Blanford
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
- Department of Materials
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35
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Plegaria JS, Yates MD, Glaven SM, Kerfeld CA. Redox Characterization of Electrode-Immobilized Bacterial Microcompartment Shell Proteins Engineered To Bind Metal Centers. ACS APPLIED BIO MATERIALS 2019; 3:685-692. [DOI: 10.1021/acsabm.9b01023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
| | - Matthew D. Yates
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Sarah M. Glaven
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Cheryl A. Kerfeld
- Environmental Genomics and Systems Biology and Molecular Biophysics and Integrated Bioimaging Divisions, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
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36
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Alwan KB, Welch EF, Blackburn NJ. Catalytic M Center of Copper Monooxygenases Probed by Rational Design. Effects of Selenomethionine and Histidine Substitution on Structure and Reactivity. Biochemistry 2019; 58:4436-4446. [PMID: 31626532 DOI: 10.1021/acs.biochem.9b00823] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The M centers of the mononuclear monooxygenases peptidylglycine monooxygenase (PHM) and dopamine β-monooxygenase bind and activate dioxygen en route to substrate hydroxylation. Recently, we reported the rational design of a protein-based model in which the CusF metallochaperone was repurposed via a His to Met mutation to act as a structural and spectroscopic biomimic. The PHM M site exhibits a number of unusual attributes, including a His2Met ligand set, a fluxional Cu(I)-S(Met) bond, tight binding of exogenous ligands CO and N3-, and complete coupling of oxygen reduction to substrate hydroxylation even at extremely low turnover rates. In particular, mutation of the Met ligand to His completely eliminates the catalytic activity despite the propensity of CuI-His3 centers to bind and activate dioxygen in other metalloenzyme systems. Here, we further develop the CusF-based model to explore methionine variants in which Met is replaced by selenomethionine (SeM) and histidine. We examine the effects on coordinate structure and exogenous ligand binding via X-ray absorption spectroscopy and electron paramagnetic resonance and probe the consequences of mutations on redox chemistry via studies of the reduction by ascorbate and oxidation via molecular oxygen. The M-site model is three-coordinate in the Cu(I) state and binds CO to form a four-coordinate carbonyl. In the oxidized forms, the coordination changes to tetragonal five-coordinate with a long axial Met ligand that like the enzymes is undetectable at either the Cu or Se K edges. The EXAFS data at the Se K edge of the SeM variant provide unique information about the nature of the Cu-methionine bond that is likewise weak and fluxional. Kinetic studies document the sluggish reactivity of the Cu(I) complexes with molecular oxygen and rapid rates of reduction of the Cu(II) complexes by ascorbate, indicating a remarkable stability of the Cu(I) state in all three derivatives. The results show little difference between the Met ligand and its SeM and His congeners and suggest that the Met contributes to catalysis in ways that are more complex than simple perturbation of the redox chemistry. Overall, the results stimulate a critical re-examination of the canonical reaction mechanisms of the mononuclear copper monooxygenases.
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Affiliation(s)
- Katherine B Alwan
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Evan F Welch
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
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North ML, Wilcox DE. Shift from Entropic Cu 2+ Binding to Enthalpic Cu + Binding Determines the Reduction Thermodynamics of Blue Copper Proteins. J Am Chem Soc 2019; 141:14329-14339. [PMID: 31433629 DOI: 10.1021/jacs.9b06836] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enthalpic and entropic components of Cu2+ and Cu+ binding to the blue copper protein azurin have been quantified with isothermal titration calorimetry (ITC) measurements and analysis, providing the first such experimental values for Cu+ binding to a protein. The high affinity of azurin for Cu2+ is entirely due to a very favorable binding entropy, while its even higher affinity for Cu+ is due to a favorable binding enthalpy and entropy. The binding thermodynamics provide insight into bond enthalpies at the blue copper site and entropic contributions from desolvation and proton displacement. These values were used in thermodynamic cycles to determine the enthalpic and entropic contributions to the free energy of reduction and thus the reduction potential. The reduction thermodynamics obtained with this method are in good agreement with previous results from temperature-dependent electrochemical measurements. The calorimetry method, however, provides new insight into contributions from the initial (oxidized) and final (reduced) states of the reduction. Since ITC measurements quantify the protons that are displaced upon metal binding, the proton transfer that is coupled with electron transfer is also determined with this method. Preliminary results for Cu2+ and Cu+ binding to the Phe114Pro variant of azurin demonstrate the insight about protein tuning of the reduction potential that is provided by the binding thermodynamics of each metal oxidation state.
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Affiliation(s)
- Molly L North
- Department of Chemistry , Dartmouth College , Hanover , New Hampshire 03755 , United States
| | - Dean E Wilcox
- Department of Chemistry , Dartmouth College , Hanover , New Hampshire 03755 , United States
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Slater JW, Marguet SC, Gray ME, Monaco HA, Sotomayor M, Shafaat HS. Power of the Secondary Sphere: Modulating Hydrogenase Activity in Nickel-Substituted Rubredoxin. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01720] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jeffrey W. Slater
- The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Sean C. Marguet
- The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Michelle E. Gray
- The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Haleigh A. Monaco
- The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Marcos Sotomayor
- The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Hannah S. Shafaat
- The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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Lin YW. Rational Design of Artificial Metalloproteins and Metalloenzymes with Metal Clusters. Molecules 2019; 24:E2743. [PMID: 31362341 PMCID: PMC6696605 DOI: 10.3390/molecules24152743] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/24/2019] [Accepted: 07/26/2019] [Indexed: 01/22/2023] Open
Abstract
Metalloproteins and metalloenzymes play important roles in biological systems by using the limited metal ions, complexes, and clusters that are associated with the protein matrix. The design of artificial metalloproteins and metalloenzymes not only reveals the structure and function relationship of natural proteins, but also enables the synthesis of artificial proteins and enzymes with improved properties and functions. Acknowledging the progress in rational design from single to multiple active sites, this review focuses on recent achievements in the design of artificial metalloproteins and metalloenzymes with metal clusters, including zinc clusters, cadmium clusters, iron-sulfur clusters, and copper-sulfur clusters, as well as noble metal clusters and others. These metal clusters were designed in both native and de novo protein scaffolds for structural roles, electron transfer, or catalysis. Some synthetic metal clusters as functional models of native enzymes are also discussed. These achievements provide valuable insights for deep understanding of the natural proteins and enzymes, and practical clues for the further design of artificial enzymes with functions comparable or even beyond those of natural counterparts.
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Affiliation(s)
- Ying-Wu Lin
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.
- Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China.
- Hunan Key Laboratory for the Design and Application of Actinide Complexes, University of South China, Hengyang 421001, China.
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40
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The Structural and Functional Diversity of Intrinsically Disordered Regions in Transmembrane Proteins. J Membr Biol 2019; 252:273-292. [DOI: 10.1007/s00232-019-00069-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/17/2019] [Indexed: 10/26/2022]
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Mirts EN, Bhagi-Damodaran A, Lu Y. Understanding and Modulating Metalloenzymes with Unnatural Amino Acids, Non-Native Metal Ions, and Non-Native Metallocofactors. Acc Chem Res 2019; 52:935-944. [PMID: 30912643 DOI: 10.1021/acs.accounts.9b00011] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Metalloproteins set the gold standard for performing important functions, including catalyzing demanding reactions under mild conditions. Designing artificial metalloenzymes (ArMs) to catalyze abiological reactions has been a major endeavor for many years, but most ArM activities are far below those of native enzymes, making them unsuitable for most pratical applications. A critical step to advance the field is to fundamentally understand what it takes to not only confer but also fine-tune ArM activities so they match those of native enzymes. Indeed, only once we can freely modulate ArM activity to rival (or surpass!) natural enzymes can the potential of ArMs be fully realized. A key to unlocking ArM potential is the observation that one metal primary coordination sphere can display a range of functions and levels of activity, leading to the realization that secondary coordination sphere (SCS) interactions are critically important. However, SCS interactions are numerous, long-range, and weak, making them very difficult to reproduce in ArMs. Furthermore, natural enzymes are tied to a small set of biologically available functional moieties from canonical amino acids and physiologically available metal ions and metallocofactors, severely limiting the chemical space available to probe and tune ArMs. In this Account, we summarize the use of unnatural amino acids (UAAs) and non-native metal ions and metallocofactors by our group and our collaborators to probe and modulate ArM functions. We incorporated isostructural UAAs in a type 1 copper (T1Cu) protein azurin to provide conclusive evidence that axial ligand hydrophobicity is a major determinant of T1Cu redunction potential ( E°'). Closely related work from other groups are also discussed. We also probed the role of protein backbone interactions that cannot be altered by standard mutagenesis by replacing the peptide bond with an ester linkage. We used insight gained from these studies to tune the E°' of azurin across the entire physiological range, the broadest range ever achieved in a single metalloprotein. Introducing UAA analogues of Tyr into ArM models of heme-copper oxidase (HCO) revealed a linear relationship between p Ka, E°', and activity. We also substituted non-native hemes and non-native metal ions for their native equivalents in these models to resolve several issues that were intractable in native HCOs and the closely related nitric oxide reductases, such as their roles in modulating substrate affinity, electron transfer rate, and activity. We incorporated abiological cofactors such as ferrocene and Mn(salen) into azurin and myoglobin, respectively, to stabilize these inorganic and organometallic compounds in water, confer abiological functions, tune their E°' and activity through SCS interactions, and show that the approach to metallocofactor anchoring and orientation can tune enantioselectivity and alter function. Replacing Cu in azurin with non-native Fe or Ni can impart novel activities, such as superoxide reduction and C-C bond formation. While progress was made, we have identified only a small fraction of the interactions that can be generally applied to ArMs to fine-tune their functions. Because SCS interactions are subtle and heavily interconnected, it has been difficult to characterize their effects quantitatively. It is vital to develop spectroscopic and computational techniques to detect and quantify their effects in both resting states and catalytic intermediates.
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Affiliation(s)
- Evan N. Mirts
- Department of Chemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi-Damodaran
- Department of Chemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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Mateljak I, Monza E, Lucas MF, Guallar V, Aleksejeva O, Ludwig R, Leech D, Shleev S, Alcalde M. Increasing Redox Potential, Redox Mediator Activity, and Stability in a Fungal Laccase by Computer-Guided Mutagenesis and Directed Evolution. ACS Catal 2019. [DOI: 10.1021/acscatal.9b00531] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Ivan Mateljak
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28094 Madrid, Spain
| | - Emanuele Monza
- Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona, Spain
- Zymvol, C/Almogavers 165, 08018 Barcelona, Spain
| | - Maria Fatima Lucas
- Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona, Spain
- Zymvol, C/Almogavers 165, 08018 Barcelona, Spain
| | - Victor Guallar
- Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona, Spain
- ICREA: Institució Catalana de Recerca i Estudis Avancats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Olga Aleksejeva
- Biomedical Sciences, Health and Society, Malmö University, 20560 Malmö, Sweden
| | - Roland Ludwig
- Department of Food Sciences and Technology, VIBT—Vienna Institute of Biotechnology, BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Donal Leech
- Department of Chemistry, National University of Ireland, Galway University Road, SW4 794 Galway, Ireland
| | - Sergey Shleev
- Biomedical Sciences, Health and Society, Malmö University, 20560 Malmö, Sweden
| | - Miguel Alcalde
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28094 Madrid, Spain
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Zahler CT, Shaw BF. What Are We Missing by Not Measuring the Net Charge of Proteins? Chemistry 2019; 25:7581-7590. [PMID: 30779227 DOI: 10.1002/chem.201900178] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Indexed: 12/21/2022]
Abstract
The net electrostatic charge (Z) of a folded protein in solution represents a bird's eye view of its surface potentials-including contributions from tightly bound metal, solvent, buffer, and cosolvent ions-and remains one of its most enigmatic properties. Few tools are available to the average biochemist to rapidly and accurately measure Z at pH≠pI. Tools that have been developed more recently seem to go unnoticed. Most scientists are content with this void and estimate the net charge of a protein from its amino acid sequence, using textbook values of pKa . Thus, Z remains unmeasured for nearly all folded proteins at pH≠pI. When marveling at all that has been learned from accurately measuring the other fundamental property of a protein-its mass-one wonders: what are we missing by not measuring the net charge of folded, solvated proteins? A few big questions immediately emerge in bioinorganic chemistry. When a single electron is transferred to a metalloprotein, does the net charge of the protein change by approximately one elementary unit of charge or does charge regulation dominate, that is, do the pKa values of most ionizable residues (or just a few residues) adjust in response to (or in concert with) electron transfer? Would the free energy of charge regulation (ΔΔGz ) account for most of the outer sphere reorganization energy associated with electron transfer? Or would ΔΔGz contribute more to the redox potential? And what about metal binding itself? When an apo-metalloprotein, bearing minimal net negative charge (e.g., Z=-2.0) binds one or more metal cations, is the net charge abolished or inverted to positive? Or do metalloproteins regulate net charge when coordinating metal ions? The author's group has recently dusted off a relatively obscure tool-the "protein charge ladder"-and used it to begin to answer these basic questions.
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Affiliation(s)
- Collin T Zahler
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76706, USA
| | - Bryan F Shaw
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76706, USA
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Abstract
Many artificial enzymes that catalyze redox reactions have important energy, environmental, and medical applications. Native metalloenzymes use a set of redox-active amino acids and cofactors as redox centers, with a potential range between -700 and +800 mV versus standard hydrogen electrode (SHE, all reduction potentials are versus SHE). The redox potentials and the orientation of redox centers in native metalloproteins are optimal for their redox chemistry. However, the limited number and potential range of native redox centers challenge the design and optimization of novel redox chemistry in metalloenzymes. Artificial metalloenzymes use non-native redox centers and could go far beyond the natural range of redox potentials for novel redox chemistry. In addition to designing protein monomers, strategies for increasing the electron transfer rate in self-assembled protein complexes and protein-electrode or -nanomaterial interfaces will be discussed. Redox reactions in proteins occur on redox active amino acid residues (Tyr, Trp, Met, Cys, etc.) and cofactors (iron sulfur clusters, flavin, heme, etc.). The redox potential of these redox centers cover a ∼1.5 V range and is optimized for their specific functions. Despite recent progress, tuning the redox potential for amino acid residues or cofactors remains challenging. Many redox-active unnatural amino acids (UAAs) can be incorporated into protein via genetic codon expansion. Their redox potentials extend the range of physiologically relevant potentials. Indeed, installing new redox cofactors with fined-tuned redox potentials is essential for designing novel redox enzymes. By combining UAA and redox cofactor incorporation, we harnessed light energy to reduce CO2 in a fluorescent protein, mimicking photosynthetic apparatus in nature. Manipulating the position and reduction potential of redox centers inside proteins is important for optimizing the electron transfer rate and the activity of artificial enzymes. Learning from the native electron transfer complex, protein-protein interactions can be enhanced by increasing the electrostatic interaction between proteins. An artificial oxidase showed close to native enzyme activity with optimized interaction with electron transfer partner and increased electron transfer efficiency. In addition to the de novo design of protein-protein interaction, protein self-assembly methods using scaffolds, such as proliferating cell nuclear antigen, to efficiently anchor enzymes and their redox partners. The self-assembly process enhances electron transfer efficiency and enzyme activity by bringing redox centers into close proximity of each other. In addition to protein self-assembly, protein-electrode or protein-nanomaterial self-assembly can also promote efficient electron transfer from inorganic materials to enzyme active sites. Such hybrid systems combine the efficiency of enzyme reactions and the robustness of electrodes or nanomaterials, often with advantageous catalytic activities. By combining these strategies, we can not only mimic some of nature's most fascinating reactions, such as photosynthesis and aerobic respiration, but also transcend nature toward environmental, energy, and health applications.
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Affiliation(s)
- Yang Yu
- Department of Biochemical Engineering and Institute for Synthetic Biosystem, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian
District, Beijing 100081, China
| | - Xiaohong Liu
- Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China
| | - Jiangyun Wang
- Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China
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45
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Smith MA, Majer SH, Vilbert AC, Lancaster KM. Controlling a burn: outer-sphere gating of hydroxylamine oxidation by a distal base in cytochrome P460. Chem Sci 2019; 10:3756-3764. [PMID: 31015919 PMCID: PMC6457333 DOI: 10.1039/c9sc00195f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 02/14/2019] [Indexed: 01/19/2023] Open
Abstract
One amino acid makes the difference between a metalloenzyme and a metalloprotein in two otherwise effectively identical cytochrome P460s.
Ammonia oxidizing bacteria (AOB) use the cytotoxic, energetic molecule hydroxylamine (NH2OH) as a source of reducing equivalents for cellular respiration. Despite disproportionation or violent decomposition being typical outcomes of reactions of NH2OH with iron, AOB and anammox heme P460 proteins including cytochrome (cyt) P460 and hydroxylamine oxidoreductase (HAO) effect controlled, stepwise oxidation of NH2OH to nitric oxide (NO). Curiously, a recently characterized cyt P460 variant from the AOB Nitrosomonas sp. AL212 is able to form all intermediates of cyt P460 catalysis, but is nevertheless incompetent for NH2OH oxidation. We now show via site-directed mutagenesis, activity assays, spectroscopy, and structural biology that this lack of activity is attributable to the absence of a critical basic glutamate residue in the distal pocket above the heme P460 cofactor. This substitution is the only distinguishing characteristic of a protein that is otherwise effectively structurally and spectroscopically identical to an active variant. This highlights and reinforces a fundamental principal of metalloenzymology: metallocofactor inner-sphere geometric and electronic structures are in many cases insufficient for imbuing reactivity; a precisely defined outer coordination sphere contributed by the polypeptide matrix can be the key differentiator between a metalloenzyme and an unreactive metalloprotein.
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Affiliation(s)
- Meghan A Smith
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
| | - Sean H Majer
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
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Leguto AJ, Smith MA, Morgada MN, Zitare UA, Murgida DH, Lancaster KM, Vila AJ. Dramatic Electronic Perturbations of Cu A Centers via Subtle Geometric Changes. J Am Chem Soc 2019; 141:1373-1381. [PMID: 30582893 DOI: 10.1021/jacs.8b12335] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CuA is a binuclear copper site acting as electron entry port in terminal heme-copper oxidases. In the oxidized form, CuA is a mixed valence pair whose electronic structure can be described using a potential energy surface with two minima, σu* and πu, that are variably populated at room temperature. We report that mutations in the first and second coordination spheres of the binuclear metallocofactor can be combined in an additive manner to tune the energy gap and, thus, the relative populations of the two lowest-lying states. A series of designed mutants span σu*/πu energy gaps ranging from 900 to 13 cm-1. The smallest gap corresponds to a variant with an effectively degenerate ground state. All engineered sites preserve the mixed-valence character of this metal center and the electron transfer functionality. An increase of the Cu-Cu distance less than 0.06 Å modifies the σu*/πu energy gap by almost 2 orders of magnitude, with longer distances eliciting a larger population of the πu state. This scenario offers a stark contrast to synthetic systems, as model compounds require a lengthening of 0.5 Å in the Cu-Cu distance to stabilize the πu state. These findings show that the tight control of the protein environment allows drastic perturbations in the electronic structure of CuA sites with minor geometric changes.
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Affiliation(s)
- Alcides J Leguto
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario and CONICET , 2000 Rosario , Argentina
| | - Meghan A Smith
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario and CONICET , 2000 Rosario , Argentina
| | - Ulises A Zitare
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires and CONICET , 1428 Buenos Aires , Argentina
| | - Daniel H Murgida
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires and CONICET , 1428 Buenos Aires , Argentina
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario and CONICET , 2000 Rosario , Argentina
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Walsh AP, Laureanti JA, Katipamula S, Chambers G, Priyadarshani N, Lense S, Bays JT, Linehan JC, Shaw WJ. Evaluating the impacts of amino acids in the second and outer coordination spheres of Rh-bis(diphosphine) complexes for CO2 hydrogenation. Faraday Discuss 2019; 215:123-140. [DOI: 10.1039/c8fd00164b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The influence of a biologically inspired second and outer coordination sphere on Rh-bis(diphosphine) CO2 hydrogenation catalysts was explored.
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Affiliation(s)
- Aaron P. Walsh
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Joseph A. Laureanti
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Sriram Katipamula
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Geoffrey M. Chambers
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Nilusha Priyadarshani
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Sheri Lense
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - J. Timothy Bays
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - John C. Linehan
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Wendy J. Shaw
- Physical and Computational Sciences Directorate
- Pacific Northwest National Laboratory
- Richland
- USA
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Bhagi-Damodaran A, Lu Y. The Periodic Table's Impact on Bioinorganic Chemistry and Biology's Selective Use of Metal Ions. STRUCTURE AND BONDING 2019; 182:153-173. [PMID: 36567794 PMCID: PMC9788643 DOI: 10.1007/430_2019_45] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Despite the availability of a vast variety of metal ions in the periodic table, biology uses only a selective few metal ions. Most of the redox active metals used belong to the first row of transition metals in the periodic table and include Fe, Co, Ni, Mn and Cu. On the other hand, Ca, Zn and Mg are the most commonly used redox inactive metals in biology. In this chapter, we discuss the periodic table's impact on bio-inorganic chemistry, by exploring reasons behind this selective choice of metals biology. A special focus is placed on the chemical and functional reasons why one metal ion is preferred over another one. We discuss the implications of metal choice in various biological processes including catalysis, electron transfer, redox sensing and signaling. We find that bioavailability of metal ions along with their redox potentials, coordination flexibility, valency and ligand affinity determine the specificity of metals for biological processes. Understanding the implications underlying the selective choice of metals of the periodic table in these biological processes can help design more efficient catalysts, more precise biosensors and more effective drugs.
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Affiliation(s)
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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Kayser B, Fereiro JA, Guo C, Cohen SR, Sheves M, Pecht I, Cahen D. Transistor configuration yields energy level control in protein-based junctions. NANOSCALE 2018; 10:21712-21720. [PMID: 30431054 DOI: 10.1039/c8nr06627b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The incorporation of proteins as functional components in electronic junctions has received much interest recently due to their diverse bio-chemical and physical properties. However, information regarding the energies of the frontier orbitals involved in their electron transport (ETp) has remained elusive. Here we employ a new method to quantitatively determine the energy position of the molecular orbital, nearest to the Fermi level (EF) of the electrode, in the electron transfer protein Azurin. The importance of the Cu(ii) redox center of Azurin is demonstrated by measuring gate-controlled conductance switching which is absent if Azurin's copper ions are removed. Comparing different electrode materials, a higher conductance and a lower gate-induced current onset is observed for the material with smaller work function, indicating that ETp via Azurin is LUMO-mediated. We use the difference in work function to calibrate the difference in gate-induced current onset for the two electrode materials, to a specific energy level shift and find that ETp via Azurin is near resonance. Our results provide a basis for mapping and studying the role of energy level positions in (bio)molecular junctions.
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Affiliation(s)
- Ben Kayser
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel.
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Dong HT, White CJ, Zhang B, Krebs C, Lehnert N. Non-Heme Diiron Model Complexes Can Mediate Direct NO Reduction: Mechanistic Insight into Flavodiiron NO Reductases. J Am Chem Soc 2018; 140:13429-13440. [DOI: 10.1021/jacs.8b08567] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hai T. Dong
- Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Corey J. White
- Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Bo Zhang
- Department of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Nicolai Lehnert
- Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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