1
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Wilson DWN, Thompson BC, Collauto A, Hooper RX, Knapp CE, Roessler MM, Musgrave RA. Mixed Valence {Ni 2+Ni 1+} Clusters as Models of Acetyl Coenzyme A Synthase Intermediates. J Am Chem Soc 2024; 146:21034-21043. [PMID: 39023163 PMCID: PMC11295191 DOI: 10.1021/jacs.4c06241] [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: 05/07/2024] [Revised: 06/12/2024] [Accepted: 06/13/2024] [Indexed: 07/20/2024]
Abstract
Acetyl coenzyme A synthase (ACS) catalyzes the formation and deconstruction of the key biological metabolite, acetyl coenzyme A (acetyl-CoA). The active site of ACS features a {NiNi} cluster bridged to a [Fe4S4]n+ cubane known as the A-cluster. The mechanism by which the A-cluster functions is debated, with few model complexes able to replicate the oxidation states, coordination features, or reactivity proposed in the catalytic cycle. In this work, we isolate the first bimetallic models of two hypothesized intermediates on the paramagnetic pathway of the ACS function. The heteroligated {Ni2+Ni1+} cluster, [K(12-crown-4)2][1], effectively replicates the coordination number and oxidation state of the proposed "Ared" state of the A-cluster. Addition of carbon monoxide to [1]- allows for isolation of a dinuclear {Ni2+Ni1+(CO)} complex, [K(12-crown-2)n][2] (n = 1-2), which bears similarity to the "ANiFeC" enzyme intermediate. Structural and electronic properties of each cluster are elucidated by X-ray diffraction, nuclear magnetic resonance, cyclic voltammetry, and UV/vis and electron paramagnetic resonance spectroscopies, which are supplemented by density functional theory (DFT) calculations. Calculations indicate that the pseudo-T-shaped geometry of the three-coordinate nickel in [1]- is more stable than the Y-conformation by 22 kcal mol-1, and that binding of CO to Ni1+ is barrierless and exergonic by 6 kcal mol-1. UV/vis absorption spectroscopy on [2]- in conjunction with time-dependent DFT calculations indicates that the square-planar nickel site is involved in electron transfer to the CO π*-orbital. Further, we demonstrate that [2]- promotes thioester synthesis in a reaction analogous to the production of acetyl coenzyme A by ACS.
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Affiliation(s)
- Daniel W. N. Wilson
- Department
of Chemistry, King’s College London, 7 Trinity Street, London SE1 1DB, U.K.
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Benedict C. Thompson
- Department
of Chemistry, King’s College London, 7 Trinity Street, London SE1 1DB, U.K.
| | - Alberto Collauto
- Department
of Chemistry and Centre for Pulse EPR Spectroscopy, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
| | - Reagan X. Hooper
- Stanford
PULSE Institute, SLAC National Accelerator
Laboratory, Menlo Park, California 94025, United States
| | - Caroline E. Knapp
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Maxie M. Roessler
- Department
of Chemistry and Centre for Pulse EPR Spectroscopy, Imperial College London, 82 Wood Lane, London W12
0BZ, U.K.
| | - Rebecca A. Musgrave
- Department
of Chemistry, King’s College London, 7 Trinity Street, London SE1 1DB, U.K.
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2
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Lewis LC, Sanabria-Gracia JA, Lee Y, Jenkins AJ, Shafaat HS. Electronic isomerism in a heterometallic nickel-iron-sulfur cluster models substrate binding and cyanide inhibition of carbon monoxide dehydrogenase. Chem Sci 2024; 15:5916-5928. [PMID: 38665523 PMCID: PMC11040638 DOI: 10.1039/d4sc00023d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 03/04/2024] [Indexed: 04/28/2024] Open
Abstract
The nickel-iron carbon monoxide dehydrogenase (CODH) enzyme uses a heterometallic nickel-iron-sulfur ([NiFe4S4]) cluster to catalyze the reversible interconversion of carbon dioxide (CO2) and carbon monoxide (CO). These reactions are essential for maintaining the global carbon cycle and offer a route towards sustainable greenhouse gas conversion but have not been successfully replicated in synthetic models, in part due to a poor understanding of the natural system. Though the general protein architecture of CODH is known, the electronic structure of the active site is not well-understood, and the mechanism of catalysis remains unresolved. To better understand the CODH enzyme, we have developed a protein-based model containing a heterometallic [NiFe3S4] cluster in the Pyrococcus furiosus (Pf) ferredoxin (Fd). This model binds small molecules such as carbon monoxide and cyanide, analogous to CODH. Multiple redox- and ligand-bound states of [NiFe3S4] Fd (NiFd) have been investigated using a suite of spectroscopic techniques, including resonance Raman, Ni and Fe K-edge X-ray absorption spectroscopy, and electron paramagnetic resonance, to resolve charge and spin delocalization across the cluster, site-specific electron density, and ligand activation. The facile movement of charge through the cluster highlights the fluidity of electron density within iron-sulfur clusters and suggests an electronic basis by which CN- inhibits the native system while the CO-bound state continues to elude isolation in CODH. The detailed characterization of isolable states that are accessible in our CODH model system provides valuable insight into unresolved enzymatic intermediates and offers design principles towards developing functional mimics of CODH.
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Affiliation(s)
- Luke C Lewis
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
| | - José A Sanabria-Gracia
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
| | - Yuri Lee
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles CA 90095 USA
| | - Adam J Jenkins
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles CA 90095 USA
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3
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Can M, Abernathy MJ, Wiley S, Griffith C, James CD, Xiong J, Guo Y, Hoffman BM, Ragsdale SW, Sarangi R. Characterization of Methyl- and Acetyl-Ni Intermediates in Acetyl CoA Synthase Formed during Anaerobic CO 2 and CO Fixation. J Am Chem Soc 2023; 145:13696-13708. [PMID: 37306669 PMCID: PMC10311460 DOI: 10.1021/jacs.3c01772] [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: 02/16/2023] [Indexed: 06/13/2023]
Abstract
The Wood-Ljungdahl Pathway is a unique biological mechanism of carbon dioxide and carbon monoxide fixation proposed to operate through nickel-based organometallic intermediates. The most unusual steps in this metabolic cycle involve a complex of two distinct nickel-iron-sulfur proteins: CO dehydrogenase and acetyl-CoA synthase (CODH/ACS). Here, we describe the nickel-methyl and nickel-acetyl intermediates in ACS completing the characterization of all its proposed organometallic intermediates. A single nickel site (Nip) within the A cluster of ACS undergoes major geometric and redox changes as it transits the planar Nip, tetrahedral Nip-CO and planar Nip-Me and Nip-Ac intermediates. We propose that the Nip intermediates equilibrate among different redox states, driven by an electrochemical-chemical (EC) coupling process, and that geometric changes in the A-cluster linked to large protein conformational changes control entry of CO and the methyl group.
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Affiliation(s)
- Mehmet Can
- Department
of Biochemistry, Faculty of Pharmacy, Ankara
Medipol University, Ankara 06050, Turkey
| | - Macon J. Abernathy
- Stanford
Synchrotron Radiation Lightsource, SLAC
National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Seth Wiley
- Biosciences
Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Claire Griffith
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Christopher D. James
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Jin Xiong
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Brian M. Hoffman
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephen W. Ragsdale
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ritimukta Sarangi
- Stanford
Synchrotron Radiation Lightsource, SLAC
National Accelerator Laboratory, Menlo Park, California 94025, United States
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4
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Selvan D, Chakraborty S. A De Novo Designed Trimeric Metalloprotein as a Ni p Model of the Acetyl-CoA Synthase. Int J Mol Sci 2023; 24:10317. [PMID: 37373464 DOI: 10.3390/ijms241210317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/30/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
We present a Nip site model of acetyl coenzyme-A synthase (ACS) within a de novo-designed trimer peptide that self-assembles to produce a homoleptic Ni(Cys)3 binding motif. Spectroscopic and kinetic studies of ligand binding demonstrate that Ni binding stabilizes the peptide assembly and produces a terminal NiI-CO complex. When the CO-bound state is reacted with a methyl donor, a new species is quickly produced with new spectral features. While the metal-bound CO is albeit unactivated, the presence of the methyl donor produces an activated metal-CO complex. Selective outer sphere steric modifications demonstrate that the physical properties of the ligand-bound states are altered differently depending on the location of the steric modification above or below the Ni site.
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Affiliation(s)
- Dhanashree Selvan
- Department of Chemistry and Biochemistry, University of Mississippi, Coulter Hall, Oxford, MS 38677, USA
| | - Saumen Chakraborty
- Department of Chemistry and Biochemistry, University of Mississippi, Coulter Hall, Oxford, MS 38677, USA
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5
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Gencic S, Duin EC, Grahame DA. The two-electron reduced A cluster in acetyl-CoA synthase: Preparation, characteristics and mechanistic implications. J Inorg Biochem 2023; 240:112098. [PMID: 36580832 DOI: 10.1016/j.jinorgbio.2022.112098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022]
Abstract
Acetyl-CoA synthase (ACS) is a central enzyme in the carbon and energy metabolism of certain anaerobic species of bacteria and archaea that catalyzes the direct synthesis and cleavage of the acetyl CC bond of acetyl-CoA by an unusual enzymatic mechanism of special interest for its use of organonickel intermediates. An Fe4S4 cluster associated with a proximal, reactive Nip and distal spectator Nid comprise the active site metal complex, known as the A cluster. Experimental and theoretical methods have uncovered much about the ACS mechanism, but have also opened new unanswered questions about the structure and reactivity of the A cluster in various intermediate forms. Here we report a method for large scale isolation of ACS with its A cluster in the acetylated state. Isolated acetyl-ACS and the two-electron reduced ACS, produced by acetyl-ACS reaction with CoA, were characterized by UV-visible and EPR spectroscopy. Reactivity with electron acceptors provided an assessment of the apparent Em for two-electron reduction of the A cluster. The results help to distinguish between alternative electronic states of the reduced cluster, provide evidence for a role of the Fe/S cluster in catalysis, and offer an explanation of why one-electron reductive activation is observed for a reaction cycle involving 2-electron chemistry.
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Affiliation(s)
- Simonida Gencic
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Evert C Duin
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
| | - David A Grahame
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
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6
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Biester A, Marcano-Delgado AN, Drennan CL. Structural Insights into Microbial One-Carbon Metabolic Enzymes Ni-Fe-S-Dependent Carbon Monoxide Dehydrogenases and Acetyl-CoA Synthases. Biochemistry 2022; 61:2797-2805. [PMID: 36137563 PMCID: PMC9782325 DOI: 10.1021/acs.biochem.2c00425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Ni-Fe-S-dependent carbon monoxide dehydrogenases (CODHs) are enzymes that interconvert CO and CO2 by using their catalytic Ni-Fe-S C-cluster and their Fe-S B- and D-clusters for electron transfer. CODHs are important in the microbiota of animals such as humans, ruminants, and termites because they can facilitate the use of CO and CO2 as carbon sources and serve to maintain redox homeostasis. The bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase (CODH/ACS) is responsible for acetate production via the Wood-Ljungdahl pathway, where acetyl-CoA is assembled from two CO2-derived one-carbon units. A Ni-Fe-S A-cluster is key to this chemistry. Whereas acetogens use the A- and C-clusters of CODH/ACS to produce acetate from CO2, methanogens use A- and C-clusters of an acetyl-CoA decarbonylase/synthase complex (ACDS) to break down acetate en route to CO2 and methane production. Here we review some of the recent advances in understanding the structure and mechanism of CODHs, CODH/ACSs, and ACDSs, their unusual metallocofactors, and their unique metabolic roles in the human gut and elsewhere.
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Affiliation(s)
- Alison Biester
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
| | - Andrea N. Marcano-Delgado
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
| | - Catherine L. Drennan
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States,Department
of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States,Howard
Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States,Bio-inspired
Solar Energy Program, Canadian Institute
for Advanced Research, Toronto, ON M5G 1M1, Canada,
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7
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Thioester synthesis by a designed nickel enzyme models prebiotic energy conversion. Proc Natl Acad Sci U S A 2022; 119:e2123022119. [PMID: 35858422 PMCID: PMC9335327 DOI: 10.1073/pnas.2123022119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The formation of carbon-carbon bonds from prebiotic precursors such as carbon dioxide represents the foundation of all primordial life processes. In extant organisms, this reaction is carried out by the carbon monoxide dehydrogenase (CODH)/acetyl coenzyme A synthase (ACS) enzyme, which performs the cornerstone reaction in the ancient Wood-Ljungdahl metabolic pathway to synthesize the key biological metabolite, acetyl-CoA. Despite its significance, a fundamental understanding of this transformation is lacking, hampering efforts to harness analogous chemistry. To address these knowledge gaps, we have designed an artificial metalloenzyme within the azurin protein scaffold as a structural, functional, and mechanistic model of ACS. We demonstrate the intermediacy of the NiI species and requirement for ordered substrate binding in the bioorganometallic carbon-carbon bond-forming reaction from the one-carbon ACS substrates. The electronic and geometric structures of the nickel-acetyl intermediate have been characterized using time-resolved optical, electron paramagnetic resonance, and X-ray absorption spectroscopy in conjunction with quantum chemical calculations. Moreover, we demonstrate that the nickel-acetyl species is chemically competent for selective acyl transfer upon thiol addition to biosynthesize an activated thioester. Drawing an analogy to the native enzyme, a mechanism for thioester generation by this ACS model has been proposed. The fundamental insight into the enzymatic process provided by this rudimentary ACS model has implications for the evolution of primitive ACS-like proteins. Ultimately, these findings offer strategies for development of highly active catalysts for sustainable generation of liquid fuels from one-carbon substrates, with potential for broad applications across diverse fields ranging from energy storage to environmental remediation.
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8
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Griego L, Woods TJ, Mirica LM. A five-coordinate Ni(I) complex supported by 1,4,7-triisopropyl-1,4,7-triazacyclononane. Chem Commun (Camb) 2022; 58:7360-7363. [PMID: 35708524 DOI: 10.1039/d2cc02516g] [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
An isolated Ni(II)-nitrosyl complex supported by the bulky tridentate 1,4,7-triisopropyl-1,4,7-triazacyclononane (iPr3TACN) ligand was obtained from the reaction of a Ni(II) dimethyl complex with NOPF6, suggesting the in situ formation of a Ni(I) species that reacts with the resulting NO product. Use of a π-acceptor ancillary isocyanide ligand led to the isolation and characterization of an uncommon 5-coordinate Ni(I) complex supported by the iPr3TACN ligand and tert-butylisocyanide.
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Affiliation(s)
- Leonel Griego
- Department of Chemistry University of Illinois at Urbana Champaign 600 S. Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Toby J Woods
- Department of Chemistry University of Illinois at Urbana Champaign 600 S. Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Liviu M Mirica
- Department of Chemistry University of Illinois at Urbana Champaign 600 S. Mathews Avenue, Urbana, Illinois, 61801, USA.
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9
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10
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Matsubara K. Well-Defined NHC-Ni Complexes as Catalysts: Preparation, Structures and Mechanistic Studies in Cross-Coupling Reactions. CHEM REC 2021; 21:3925-3942. [PMID: 34596959 DOI: 10.1002/tcr.202100204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/12/2021] [Indexed: 02/06/2023]
Abstract
Developmental studies are ongoing to discover a way to utilise new N-heterocyclic carbene (NHC)-Ni complexes as catalysts. Using a bulky NHC ligand, it is possible to synthesise an NHC/phosphine-mixed heteroleptic Ni(II) complex, which can serve as an excellent catalyst for various cross-coupling reactions. During the study of the reaction mechanisms using these Ni complexes, NHC-Ni(I) complexes were accidentally discovered, and it was observed that they exhibit excellent catalytic activity for cross-coupling reactions. The possibility of the presence of NHC-Ni(I) intermediates in these catalytic reaction pathways has been experimentally demonstrated. Depending on the type of reaction, dinuclear Ni(I) and mononuclear Ni(I) complexes can function as intermediates. The results of the investigation of each reaction mechanism are summarised, and the prospects are described.
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Affiliation(s)
- Kouki Matsubara
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka, 814-0180, Japan
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11
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Lewis LC, Shafaat HS. Reversible Electron Transfer and Substrate Binding Support [NiFe 3S 4] Ferredoxin as a Protein-Based Model for [NiFe] Carbon Monoxide Dehydrogenase. Inorg Chem 2021; 60:13869-13875. [PMID: 34488341 DOI: 10.1021/acs.inorgchem.1c01323] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The nickel-iron carbon monoxide dehydrogenase (CODH) enzyme catalyzes the reversible and selective interconversion of carbon dioxide (CO2) to carbon monoxide (CO) with high rates and negligible overpotential. Despite decades of research, many questions remain about this complex metalloenzyme system. A simplified model enzyme could provide substantial insight into biological carbon cycling. Here, we demonstrate reversible electron transfer and binding of both CO and cyanide, a substrate and an inhibitor of CODH, respectively, in a Pyrococcus furiosus (Pf) ferredoxin (Fd) protein that has been reconstituted with a nickel-iron sulfide cluster ([NiFe3S4] Fd). The [NiFe3S4] cluster mimics the core of the native CODH active site and thus serves as a protein-based structural model of the CODH subsite. Notably, despite binding cyanide, no CO binding is observed for the physiological [Fe4S4] clusters in Pf Fd, providing chemical rationale underlying the evolution of a site-differentiated cluster for substrate conversion in native CODH. The demonstration of a substrate-binding metalloprotein model of CODH sets the stage for high-resolution spectroscopic and mechanistic studies correlating the subsite structure and function, ultimately guiding the design of anthropogenic catalysts that harness the advantages of CODH for effective CO2 reduction.
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Affiliation(s)
- Luke C Lewis
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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12
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Naughton KJ, Treviño RE, Moore PJ, Wertz AE, Dickson JA, Shafaat HS. In Vivo Assembly of a Genetically Encoded Artificial Metalloenzyme for Hydrogen Production. ACS Synth Biol 2021; 10:2116-2120. [PMID: 34370434 DOI: 10.1021/acssynbio.1c00177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The genetic encoding of artificial enzymes represents a substantial advantage relative to traditional molecular catalyst optimization, as laboratory-based directed evolution coupled with high-throughput screening methods can provide rapid development and functional characterization of enzyme libraries. However, these techniques have been of limited utility in the field of artificial metalloenzymes due to the need for in vitro cofactor metalation. Here, we report the development of methodology for in vivo production of nickel-substituted rubredoxin, an artificial metalloenzyme that is a structural, functional, and mechanistic mimic of the [NiFe] hydrogenases. Direct voltammetry on cell lysate establishes precedent for the development of an electrochemical screen. This technique will be broadly applicable to the in vivo generation of artificial metalloenzymes that require a non-native metal cofactor, offering a route for rapid enzyme optimization and setting the stage for integration of artificial metalloenzymes into biochemical pathways within diverse hosts.
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Affiliation(s)
- Kassandra J. Naughton
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Regina E. Treviño
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Peter J. Moore
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Ashlee E. Wertz
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - J. Alex Dickson
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Hannah S. Shafaat
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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13
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De novo biosynthesis of a nonnatural cobalt porphyrin cofactor in E. coli and incorporation into hemoproteins. Proc Natl Acad Sci U S A 2021; 118:2017625118. [PMID: 33850014 DOI: 10.1073/pnas.2017625118] [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] [Indexed: 02/07/2023] Open
Abstract
Enzymes that bear a nonnative or artificially introduced metal center can engender novel reactivity and enable new spectroscopic and structural studies. In the case of metal-organic cofactors, such as metalloporphyrins, no general methods exist to build and incorporate new-to-nature cofactor analogs in vivo. We report here that a common laboratory strain, Escherichia coli BL21(DE3), biosynthesizes cobalt protoporphyrin IX (CoPPIX) under iron-limited, cobalt-rich growth conditions. In supplemented minimal media containing CoCl2, the metabolically produced CoPPIX is directly incorporated into multiple hemoproteins in place of native heme b (FePPIX). Five cobalt-substituted proteins were successfully expressed with this new-to-nature cobalt porphyrin cofactor: myoglobin H64V V68A, dye decolorizing peroxidase, aldoxime dehydratase, cytochrome P450 119, and catalase. We show conclusively that these proteins incorporate CoPPIX, with the CoPPIX making up at least 95% of the total porphyrin content. In cases in which the native metal ligand is a sulfur or nitrogen, spectroscopic parameters are consistent with retention of native metal ligands. This method is an improvement on previous approaches with respect to both yield and ease-of-implementation. Significantly, this method overcomes a long-standing challenge to incorporate nonnatural cofactors through de novo biosynthesis. By utilizing a ubiquitous laboratory strain, this process will facilitate spectroscopic studies and the development of enzymes for CoPPIX-mediated biocatalysis.
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14
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Anderson ME, Marks MB, Cundari TR. Bifunctional activation of methane by bioinspired transition metal complexes. A simple methane protease model. COMPUT THEOR CHEM 2021. [DOI: 10.1016/j.comptc.2021.113180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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15
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DiPrimio DJ, Holland PL. Repurposing metalloproteins as mimics of natural metalloenzymes for small-molecule activation. J Inorg Biochem 2021; 219:111430. [PMID: 33873051 DOI: 10.1016/j.jinorgbio.2021.111430] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 12/12/2022]
Abstract
Artificial metalloenzymes (ArMs) consist of an unnatural metal or cofactor embedded in a protein scaffold, and are an excellent platform for applying the concepts of protein engineering to catalysis. In this Focused Review, we describe the application of ArMs as simple, tunable artificial models of the active sites of complex natural metalloenzymes for small-molecule activation. In this sense, ArMs expand the strategies of synthetic model chemistry to protein-based supporting ligands with potential for participation from the second coordination sphere. We focus specifically on ArMs that are structural, spectroscopic, and functional models of enzymes for activation of small molecules like CO, CO2, O2, N2, and NO, as well as production/consumption of H2. These ArMs give insight into the identities and roles of metalloenzyme structural features within and near the cofactor. We give examples of ArM work relevant to hydrogenases, acetyl-coenzyme A synthase, superoxide dismutase, heme oxygenases, nitric oxide reductase, methyl-coenzyme M reductase, copper-O2 enzymes, and nitrogenases.
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Affiliation(s)
- Daniel J DiPrimio
- Department of Chemistry, Yale University, New Haven, CT, 06520, United States
| | - Patrick L Holland
- Department of Chemistry, Yale University, New Haven, CT, 06520, United States.
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16
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Ghosh AC, Duboc C, Gennari M. Synergy between metals for small molecule activation: Enzymes and bio-inspired complexes. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213606] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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17
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Kisgeropoulos EC, Manesis AC, Shafaat HS. Ligand Field Inversion as a Mechanism to Gate Bioorganometallic Reactivity: Investigating a Biochemical Model of Acetyl CoA Synthase Using Spectroscopy and Computation. J Am Chem Soc 2021; 143:849-867. [PMID: 33415980 DOI: 10.1021/jacs.0c10135] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biological global carbon cycle is largely regulated through microbial nickel enzymes, including carbon monoxide dehydrogenase (CODH), acetyl coenzyme A synthase (ACS), and methyl coenzyme M reductase (MCR). These systems are suggested to utilize organometallic intermediates during catalysis, though characterization of these species has remained challenging. We have established a mutant of nickel-substituted azurin as a scaffold upon which to develop protein-based models of enzymatic intermediates, including the organometallic states of ACS. In this work, we report the comprehensive investigation of the S = 1/2 Ni-CO and Ni-CH3 states using pulsed EPR spectroscopy and computational techniques. While the Ni-CO state shows conventional metal-ligand interactions and a classical ligand field, the Ni-CH3 hyperfine interactions between the methyl protons and the nickel indicate a closer distance than would be expected for an anionic methyl ligand. Structural analysis instead suggests a near-planar methyl ligand that can be best described as cationic. Consistent with this conclusion, the frontier molecular orbitals of the Ni-CH3 species indicate a ligand-centered LUMO, with a d9 population on the metal center, rather than the d7 population expected for a typical metal-alkyl species generated by oxidative addition. Collectively, these data support the presence of an inverted ligand field configuration for the Ni-CH3 Az species, in which the lowest unoccupied orbital is centered on the ligands rather than the more electropositive metal. These analyses provide the first evidence for an inverted ligand field within a biological system. The functional relevance of the electronic structures of both the Ni-CO and Ni-CH3 species are discussed in the context of native ACS, and an inverted ligand field is proposed as a mechanism by which to gate reactivity both within ACS and in other thiolate-containing metalloenzymes.
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Affiliation(s)
- Effie C Kisgeropoulos
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Anastasia C Manesis
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
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18
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Cohen SE, Can M, Wittenborn EC, Hendrickson RA, Ragsdale SW, Drennan CL. Crystallographic Characterization of the Carbonylated A-Cluster in Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase. ACS Catal 2020; 10:9741-9746. [PMID: 33495716 PMCID: PMC7819276 DOI: 10.1021/acscatal.0c03033] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/10/2020] [Indexed: 12/30/2022]
Abstract
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The
Wood–Ljungdahl pathway allows for autotrophic bacterial
growth on carbon dioxide, with the last step in acetyl-CoA synthesis
catalyzed by the bifunctional enzyme carbon monoxide dehydrogenase/acetyl-CoA
synthase (CODH/ACS). ACS uses a complex Ni–Fe–S metallocluster
termed the A-cluster to assemble acetyl-CoA from carbon monoxide,
a methyl moiety and coenzyme A. Here, we report the crystal structure
of CODH/ACS from Moorella thermoacetica with substrate
carbon monoxide bound at the A-cluster, a state previously uncharacterized
by crystallography. Direct structural characterization of this state
highlights the role of second sphere residues and conformational dynamics
in acetyl-CoA assembly, the biological equivalent of the Monsanto
process.
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Affiliation(s)
- Steven E. Cohen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mehmet Can
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 04109, United States
| | - Elizabeth C. Wittenborn
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Rachel A. Hendrickson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stephen W. Ragsdale
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 04109, United States
| | - Catherine L. Drennan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Howard Hughes Medical Institute, Cambridge, Massachusetts 02139, United States
- Bio-inspired Solar Energy Program, Canadian Institute for Advanced Research, Toronto, ON M5G 1M1, Canada
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19
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James CD, Wiley S, Ragsdale SW, Hoffman BM. 13C Electron Nuclear Double Resonance Spectroscopy Shows Acetyl-CoA Synthase Binds Two Substrate CO in Multiple Binding Modes and Reveals the Importance of a CO-Binding "Alcove". J Am Chem Soc 2020; 142:15362-15370. [PMID: 32786751 DOI: 10.1021/jacs.0c05950] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
EPR and Electron Nuclear Double Resonance spectroscopies here characterize CO binding to the active-site A cluster of wild-type (WT) Acetyl-CoA Synthase (ACS) and two variants, F229W and F229A. The A-cluster binds CO to a proximal Ni (Nip) that bridges a [4Fe-4S] cluster and a distal Nid. An alcove seen in the ACS crystal structure near the A-cluster, defined by hydrophobic residues including F229, forms a cage surrounding a Xe mimic of CO. Previously, we only knew WT ACS bound a single CO to form the Ared-CO intermediate, containing Nip(I)-CO with CO located on the axis of the dz2 odd-electron orbital (g⊥ > g|| ∼ 2). Here, the two-dimensional field-frequency pattern of 2K-35 GHz 13C-ENDOR spectra collected across the Ared-CO EPR envelope reveals a second CO bound in the dz2 orbital's equatorial plane. This WT A-cluster conformer dominates the nearly conservative F229W variant, but 13C-ENDOR reveals a minority "A" conformation with (g|| > g⊥ ∼ 2) characteristic of a "cloverleaf" (e.g., dx2-y2) odd-electron orbital, with Nip binding two, apparently "in-plane" CO. Disruption of the alcove through introduction of the smaller alanine residue in the F229A variant diminishes conversion to Ni(I) ∼ 10-fold and introduces extensive cluster flexibility. 13C-ENDOR shows the F229A cluster is mostly (60%) in the "A" conformation but with ∼20% each of the WT conformer and an "O" state in which dz2 Nip(I) (g⊥ > g|| ∼ 2) surprisingly lacks CO. This paper thus demonstrates the importance of an intact alcove in forming and stabilizing the Ni(I)-CO intermediate in the Wood-Ljungdahl pathway of anaerobic CO and CO2 fixation.
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Affiliation(s)
- Christopher D James
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Seth Wiley
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606 United States
| | - Stephen W Ragsdale
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606 United States
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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