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Scott AG, Szilagyi RK, Mulder DW, Ratzloff MW, Byer AS, King PW, Broderick WE, Shepard EM, Broderick JB. Compositional and structural insights into the nature of the H-cluster precursor on HydF. Dalton Trans 2018; 47:9521-9535. [PMID: 29964288 DOI: 10.1039/c8dt01654b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Assembly of an active [FeFe]-hydrogenase requires dedicated maturation enzymes that generate the active-site H-cluster: the radical SAM enzymes HydE and HydG synthesize the unusual non-protein ligands - carbon monoxide, cyanide, and dithiomethylamine - while the GTPase HydF serves as a scaffold for assembly of the 2Fe subcluster containing these ligands. In the current study, enzymatically cluster-loaded HydF ([2Fe]F) is produced by co-expression with HydE and HydG in an Escherichia coli host followed by isolation and examination by FTIR and EPR spectroscopy. FTIR reveals the presence of well-defined terminal CO and CN- ligands; however, unlike in the [FeFe]-hydrogenase, no bridging CO is observed. Exposure of this loaded HydF to exogenous CO or H2 produces no significant changes to the FTIR spectrum, indicating that, unlike in the [FeFe]-hydrogenase, the 2Fe cluster in loaded HydF is coordinatively saturated and relatively unreactive. EPR spectroscopy reveals the presence of both [4Fe-4S] and [2Fe-2S] clusters on this loaded HydF, but provides no direct evidence for these being linked to the [2Fe]F. Using the chemical reactivity and FTIR data, a large collection of computational models were evaluated. Their scaled quantum chemical vibrational spectra allowed us to score various [2Fe]F structures in terms of their ability to reproduce the diatomic stretching frequencies observed in the FTIR experimental spectra. Collectively, the results provide new insights that support the presence of a diamagnetic, but spin-polarized FeI-FeI oxidation state for the [2Fe]F precursor cluster that is coordinated by 4 CO and 2 CN- ligands, and bridged to an adjacent iron-sulfur cluster through one of the CN- ligands.
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Affiliation(s)
- Anna G Scott
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA.
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2
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Kubas A, Maszota P. Theoretical Insights into the Unique Ligation of [Fe
4
S
4
] Iron–Sulfur Clusters. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Adam Kubas
- Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01‐224 Warsaw Poland
| | - Paweł Maszota
- Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01‐224 Warsaw Poland
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3
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Shepard EM, Byer AS, Aggarwal P, Betz JN, Scott AG, Shisler KA, Usselman RJ, Eaton GR, Eaton SS, Broderick JB. Electron Spin Relaxation and Biochemical Characterization of the Hydrogenase Maturase HydF: Insights into [2Fe-2S] and [4Fe-4S] Cluster Communication and Hydrogenase Activation. Biochemistry 2017; 56:3234-3247. [PMID: 28525271 PMCID: PMC5490485 DOI: 10.1021/acs.biochem.7b00169] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nature utilizes [FeFe]-hydrogenase enzymes to catalyze the interconversion between H2 and protons and electrons. Catalysis occurs at the H-cluster, a carbon monoxide-, cyanide-, and dithiomethylamine-coordinated 2Fe subcluster bridged via a cysteine to a [4Fe-4S] cluster. Biosynthesis of this unique metallocofactor is accomplished by three maturase enzymes denoted HydE, HydF, and HydG. HydE and HydG belong to the radical S-adenosylmethionine superfamily of enzymes and synthesize the nonprotein ligands of the H-cluster. These enzymes interact with HydF, a GTPase that acts as a scaffold or carrier protein during 2Fe subcluster assembly. Prior characterization of HydF demonstrated the protein exists in both dimeric and tetrameric states and coordinates both [4Fe-4S]2+/+ and [2Fe-2S]2+/+ clusters [Shepard, E. M., Byer, A. S., Betz, J. N., Peters, J. W., and Broderick, J. B. (2016) Biochemistry 55, 3514-3527]. Herein, electron paramagnetic resonance (EPR) is utilized to characterize the [2Fe-2S]+ and [4Fe-4S]+ clusters bound to HydF. Examination of spin relaxation times using pulsed EPR in HydF samples exhibiting both [4Fe-4S]+ and [2Fe-2S]+ cluster EPR signals supports a model in which the two cluster types either are bound to widely separated sites on HydF or are not simultaneously bound to a single HydF species. Gel filtration chromatographic analyses of HydF spectroscopic samples strongly suggest the [2Fe-2S]+ and [4Fe-4S]+ clusters are coordinated to the dimeric form of the protein. Lastly, we examined the 2Fe subcluster-loaded form of HydF and showed the dimeric state is responsible for [FeFe]-hydrogenase activation. Together, the results indicate a specific role for the HydF dimer in the H-cluster biosynthesis pathway.
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Affiliation(s)
- Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Amanda S Byer
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Priyanka Aggarwal
- Department of Chemistry and Biochemistry, University of Denver , Denver, Colorado 80208, United States
| | - Jeremiah N Betz
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Anna G Scott
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Krista A Shisler
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Robert J Usselman
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver , Denver, Colorado 80208, United States
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver , Denver, Colorado 80208, United States
| | - Joan B Broderick
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
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4
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Caserta G, Pecqueur L, Adamska-Venkatesh A, Papini C, Roy S, Artero V, Atta M, Reijerse E, Lubitz W, Fontecave M. Structural and functional characterization of the hydrogenase-maturation HydF protein. Nat Chem Biol 2017; 13:779-784. [DOI: 10.1038/nchembio.2385] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 03/06/2017] [Indexed: 11/09/2022]
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5
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Shepard EM, Byer AS, Betz JN, Peters JW, Broderick JB. A Redox Active [2Fe-2S] Cluster on the Hydrogenase Maturase HydF. Biochemistry 2016; 55:3514-27. [PMID: 27232385 DOI: 10.1021/acs.biochem.6b00528] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
[FeFe]-hydrogenases are nature's most prolific hydrogen catalysts, excelling at facilely interconverting H2 and protons. The catalytic core common to all [FeFe]-hydrogenases is a complex metallocofactor, referred to as the H-cluster, which is composed of a standard [4Fe-4S] cluster linked through a bridging thiolate to a 2Fe subcluster harboring dithiomethylamine, carbon monoxide, and cyanide ligands. This 2Fe subcluster is synthesized and inserted into [FeFe]-hydrogenase by three maturase enzymes denoted HydE, HydF, and HydG. HydE and HydG are radical S-adenosylmethionine enzymes and synthesize the nonprotein ligands of the H-cluster. HydF is a GTPase that functions as a scaffold or carrier for 2Fe subcluster production. Herein, we utilize UV-visible, circular dichroism, and electron paramagnetic resonance spectroscopic studies to establish the existence of redox active [4Fe-4S] and [2Fe-2S] clusters bound to HydF. We have used spectroelectrochemical titrations to assign iron-sulfur cluster midpoint potentials, have shown that HydF purifies with a reduced [2Fe-2S] cluster in the absence of exogenous reducing agents, and have tracked iron-sulfur cluster spectroscopic changes with quaternary structural perturbations. Our results provide an important foundation for understanding the maturation process by defining the iron-sulfur cluster content of HydF prior to its interaction with HydE and HydG. We speculate that the [2Fe-2S] cluster of HydF either acts as a placeholder for HydG-derived Fe(CO)2CN species or serves as a scaffold for 2Fe subcluster assembly.
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Affiliation(s)
- Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Amanda S Byer
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Jeremiah N Betz
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - John W Peters
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Joan B Broderick
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
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6
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Darensbourg MY, Llobet A. Preface for Small Molecule Activation: From Biological Principles to Energy Applications. Part 3: Small Molecules Related to (Artificial) Photosynthesis. Inorg Chem 2016; 55:371-7. [PMID: 26782691 DOI: 10.1021/acs.inorgchem.5b02925] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Marcetta Y Darensbourg
- Department of Chemistry, Texas A&M University , College Station, Texas 77845, United States
| | - Antoni Llobet
- Departament de Quı́mica, Universitat Autònoma de Barcelona , Cerdanyola del Vallès, 08193 Barcelona, Spain
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7
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Suess DLM, Kuchenreuther JM, De La Paz L, Swartz JR, Britt RD. Biosynthesis of the [FeFe] Hydrogenase H Cluster: A Central Role for the Radical SAM Enzyme HydG. Inorg Chem 2016; 55:478-87. [PMID: 26703931 PMCID: PMC4780679 DOI: 10.1021/acs.inorgchem.5b02274] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hydrogenase enzymes catalyze the rapid and reversible interconversion of H2 with protons and electrons. The active site of the [FeFe] hydrogenase is the H cluster, which consists of a [4Fe-4S]H subcluster linked to an organometallic [2Fe]H subcluster. Understanding the biosynthesis and catalytic mechanism of this structurally unusual active site will aid in the development of synthetic and biological hydrogenase catalysts for applications in solar fuel generation. The [2Fe]H subcluster is synthesized and inserted by three maturase enzymes-HydE, HydF, and HydG-in a complex process that involves inorganic, organometallic, and organic radical chemistry. HydG is a member of the radical S-adenosyl-l-methionine (SAM) family of enzymes and is thought to play a prominent role in [2Fe]H subcluster biosynthesis by converting inorganic Fe(2+), l-cysteine (Cys), and l-tyrosine (Tyr) into an organometallic [(Cys)Fe(CO)2(CN)](-) intermediate that is eventually incorporated into the [2Fe]H subcluster. In this Forum Article, the mechanism of [2Fe]H subcluster biosynthesis is discussed with a focus on how this key [(Cys)Fe(CO)2(CN)](-) species is formed. Particular attention is given to the initial metallocluster composition of HydG, the modes of substrate binding (Fe(2+), Cys, Tyr, and SAM), the mechanism of SAM-mediated Tyr cleavage to CO and CN(-), and the identification of the final organometallic products of the reaction.
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Affiliation(s)
- Daniel L. M. Suess
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Jon M. Kuchenreuther
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Liliana De La Paz
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - James R. Swartz
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
| | - R. David Britt
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
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8
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Abstract
Proton reduction and H2 oxidation are key elementary reactions for solar fuel production. Hydrogenases interconvert H+ and H2 with remarkable efficiency and have therefore received much attention in this context. For [FeFe]-hydrogenases, catalysis occurs at a unique cofactor called the H-cluster. In this article, we discuss ways in which EPR spectroscopy has elucidated aspects of the bioassembly of the H-cluster, with a focus on four case studies: EPR spectroscopic identification of a radical en route to the CO and CN- ligands of the H-cluster, tracing 57Fe from the maturase HydG into the H-cluster, characterization of the auxiliary Fe-S cluster in HydG, and isotopic labeling of the CN- ligands of HydA for electronic structure studies of its Hox state. Advances in cell-free maturation protocols have enabled several of these mechanistic studies, and understanding H-cluster maturation may in turn provide insights leading to improvements in hydrogenase production for biotechnological applications.
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Affiliation(s)
- Daniel L. M. Suess
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - R. David Britt
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
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9
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Peters JW, Schut GJ, Boyd ES, Mulder DW, Shepard EM, Broderick JB, King PW, Adams MWW. [FeFe]- and [NiFe]-hydrogenase diversity, mechanism, and maturation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1350-69. [PMID: 25461840 DOI: 10.1016/j.bbamcr.2014.11.021] [Citation(s) in RCA: 273] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/10/2014] [Accepted: 11/16/2014] [Indexed: 11/29/2022]
Abstract
The [FeFe]- and [NiFe]-hydrogenases catalyze the formal interconversion between hydrogen and protons and electrons, possess characteristic non-protein ligands at their catalytic sites and thus share common mechanistic features. Despite the similarities between these two types of hydrogenases, they clearly have distinct evolutionary origins and likely emerged from different selective pressures. [FeFe]-hydrogenases are widely distributed in fermentative anaerobic microorganisms and likely evolved under selective pressure to couple hydrogen production to the recycling of electron carriers that accumulate during anaerobic metabolism. In contrast, many [NiFe]-hydrogenases catalyze hydrogen oxidation as part of energy metabolism and were likely key enzymes in early life and arguably represent the predecessors of modern respiratory metabolism. Although the reversible combination of protons and electrons to generate hydrogen gas is the simplest of chemical reactions, the [FeFe]- and [NiFe]-hydrogenases have distinct mechanisms and differ in the fundamental chemistry associated with proton transfer and control of electron flow that also help to define catalytic bias. A unifying feature of these enzymes is that hydrogen activation itself has been restricted to one solution involving diatomic ligands (carbon monoxide and cyanide) bound to an Fe ion. On the other hand, and quite remarkably, the biosynthetic mechanisms to produce these ligands are exclusive to each type of enzyme. Furthermore, these mechanisms represent two independent solutions to the formation of complex bioinorganic active sites for catalyzing the simplest of chemical reactions, reversible hydrogen oxidation. As such, the [FeFe]- and [NiFe]-hydrogenases are arguably the most profound case of convergent evolution. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
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Affiliation(s)
- John W Peters
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Gerrit J Schut
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Eric S Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - David W Mulder
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Joan B Broderick
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Paul W King
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
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10
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Broderick JB, Byer AS, Duschene KS, Duffus BR, Betz JN, Shepard EM, Peters JW. H-cluster assembly during maturation of the [FeFe]-hydrogenase. J Biol Inorg Chem 2014; 19:747-57. [PMID: 24972661 DOI: 10.1007/s00775-014-1168-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 06/03/2014] [Indexed: 11/28/2022]
Abstract
The organometallic H-cluster at the active site of the [FeFe]-hydrogenase serves as the site of reversible binding and reduction of protons to produce H2. The H-cluster is unique in biology, and consists of a 2Fe subcluster tethered to a typical [4Fe-4S] cluster by a single cysteine ligand. The remaining ligands to the 2Fe subcluster include three carbon monoxides, two cyanides, and a dithiomethylamine. This mini-review will focus on the significant advances in recent years in understanding the pathway for H-cluster biosynthesis, as well as the structures, roles, and mechanisms of the three enzymes directly involved.
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Affiliation(s)
- Joan B Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT, 59717, USA,
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11
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Shepard EM, Mus F, Betz JN, Byer AS, Duffus BR, Peters JW, Broderick JB. [FeFe]-hydrogenase maturation. Biochemistry 2014; 53:4090-104. [PMID: 24878200 DOI: 10.1021/bi500210x] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Hydrogenases are metalloenzymes that catalyze the reversible reduction of protons at unusual metal centers. This Current Topic discusses recent advances in elucidating the steps involved in the biosynthesis of the complex metal cluster at the [FeFe]-hydrogenase (HydA) active site, known as the H-cluster. The H-cluster is composed of a 2Fe subcluster that is anchored within the active site by a bridging cysteine thiolate to a [4Fe-4S] cubane. The 2Fe subcluster contains carbon monoxide, cyanide, and bridging dithiolate ligands. H-cluster biosynthesis is now understood to occur stepwise; standard iron-sulfur cluster assembly machinery builds the [4Fe-4S] cubane of the H-cluster, while three specific maturase enzymes known as HydE, HydF, and HydG assemble the 2Fe subcluster. HydE and HydG are both radical S-adenosylmethionine enzymes that interact with an iron-sulfur cluster binding GTPase scaffold, HydF, during the construction of the 2Fe subcluster moiety. In an unprecedented biochemical reaction, HydG cleaves tyrosine and decomposes the resulting dehydroglycine into carbon monoxide and cyanide ligands. The role of HydE in the biosynthetic pathway remains undefined, although it is hypothesized to be critical for the synthesis of the bridging dithiolate. HydF is the site where the complete 2Fe subcluster is formed and ultimately delivered to the immature hydrogenase protein in the final step of [FeFe]-hydrogenase maturation. This work addresses the roles of and interactions among HydE, HydF, HydG, and HydA in the formation of the mature [FeFe]-hydrogenase.
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Affiliation(s)
- Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
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12
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Broderick JB, Duffus B, Duschene KS, Shepard EM. Radical S-adenosylmethionine enzymes. Chem Rev 2014; 114:4229-317. [PMID: 24476342 PMCID: PMC4002137 DOI: 10.1021/cr4004709] [Citation(s) in RCA: 584] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Joan B. Broderick
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Benjamin
R. Duffus
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Kaitlin S. Duschene
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Eric M. Shepard
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
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13
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Affiliation(s)
- Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Hideaki Ogata
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Olaf Rüdiger
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Edward Reijerse
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
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14
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Berggren G, Garcia-Serres R, Brazzolotto X, Clemancey M, Gambarelli S, Atta M, Latour JM, Hernández HL, Subramanian S, Johnson MK, Fontecave M. An EPR/HYSCORE, Mössbauer, and resonance Raman study of the hydrogenase maturation enzyme HydF: a model for N-coordination to [4Fe-4S] clusters. J Biol Inorg Chem 2014; 19:75-84. [PMID: 24240692 PMCID: PMC4439245 DOI: 10.1007/s00775-013-1062-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/30/2013] [Indexed: 10/26/2022]
Abstract
The biosynthesis of the organometallic H cluster of [Fe-Fe] hydrogenase requires three accessory proteins, two of which (HydE and HydG) belong to the radical S-adenosylmethionine enzyme superfamily. The third, HydF, is an Fe-S protein with GTPase activity. The [4Fe-4S] cluster of HydF is bound to the polypeptide chain through only the three, conserved, cysteine residues present in the binding sequence motif CysXHisX(46-53)HisCysXXCys. However, the involvement of the two highly conserved histidines as a fourth ligand for the cluster coordination is controversial. In this study, we set out to characterize further the [4Fe-4S] cluster of HydF using Mössbauer, EPR, hyperfine sublevel correlation (HYSCORE), and resonance Raman spectroscopy in order to investigate the influence of nitrogen ligands on the spectroscopic properties of [4Fe-4S](2+/+) clusters. Our results show that Mössbauer, resonance Raman, and EPR spectroscopy are not able to readily discriminate between the imidazole-coordinated [4Fe-4S] cluster and the non-imidazole-bound [4Fe-4S] cluster with an exchangeable fourth ligand that is present in wild-type HydF. HYSCORE spectroscopy, on the other hand, detects the presence of an imidazole/histidine ligand on the cluster on the basis of the appearance of a specific spectral pattern in the strongly coupled region, with a coupling constant of approximately 6 MHz. We also discovered that a His-tagged version of HydF, with a hexahistidine tag at the N-terminus, has a [4Fe-4S] cluster coordinated by one histidine from the tag. This observation strongly indicates that care has to be taken in the analysis of data obtained on tagged forms of metalloproteins.
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Affiliation(s)
- Gustav Berggren
- Laboratoire de Chimie et Biologie des Métaux, Équipe «Biocatalyse», Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/Biocat, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, 17, rue des Martyrs, Grenoble, France
| | - Ricardo Garcia-Serres
- Laboratoire de Chimie et Biologie des Métaux, Équipe “Physicochimie des Métaux en Biologie”, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/pmb, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, Grenoble, France
| | - Xavier Brazzolotto
- Laboratoire de Chimie et Biologie des Métaux, Équipe «Biocatalyse», Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/Biocat, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, 17, rue des Martyrs, Grenoble, France
| | - Martin Clemancey
- Laboratoire de Chimie et Biologie des Métaux, Équipe “Physicochimie des Métaux en Biologie”, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/pmb, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, Grenoble, France
| | - Serge Gambarelli
- Laboratoire “Résonance Magnétique”, Université Joseph Fourier, Grenoble 1/CEA/Institut Nanoscience et Cryogénie/SCIB, UMR-E3, Grenoble, France
| | - Mohamed Atta
- Laboratoire de Chimie et Biologie des Métaux, Équipe «Biocatalyse», Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/Biocat, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, 17, rue des Martyrs, Grenoble, France
| | - Jean-Marc Latour
- Laboratoire de Chimie et Biologie des Métaux, Équipe “Physicochimie des Métaux en Biologie”, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/pmb, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, Grenoble, France
| | - Heather L. Hernández
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA
| | - Sowmya Subramanian
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA
| | - Michael K. Johnson
- Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA
| | - Marc Fontecave
- Laboratoire de Chimie et Biologie des Métaux, Équipe «Biocatalyse», Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV-LCBM/Biocat, UMR 5249 CEA/CNRS/UJF, CEA/Grenoble, 17, rue des Martyrs, Grenoble, France
- Collége de France, 11 place Marcellin-Berthelot, Paris, France
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