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Duan J, Senger M, Esselborn J, Engelbrecht V, Wittkamp F, Apfel UP, Hofmann E, Stripp ST, Happe T, Winkler M. Crystallographic and spectroscopic assignment of the proton transfer pathway in [FeFe]-hydrogenases. Nat Commun 2018; 9:4726. [PMID: 30413719 PMCID: PMC6226526 DOI: 10.1038/s41467-018-07140-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/18/2018] [Indexed: 11/29/2022] Open
Abstract
The unmatched catalytic turnover rates of [FeFe]-hydrogenases require an exceptionally efficient proton-transfer (PT) pathway to shuttle protons as substrates or products between bulk water and catalytic center. For clostridial [FeFe]-hydrogenase CpI such a pathway has been proposed and analyzed, but mainly on a theoretical basis. Here, eleven enzyme variants of two different [FeFe]-hydrogenases (CpI and HydA1) with substitutions in the presumptive PT-pathway are examined kinetically, spectroscopically, and crystallographically to provide solid experimental proof for its role in hydrogen-turnover. Targeting key residues of the PT-pathway by site directed mutagenesis significantly alters the pH-activity profile of these variants and in presence of H2 their cofactor is trapped in an intermediate state indicative of precluded proton-transfer. Furthermore, crystal structures coherently explain the individual levels of residual activity, demonstrating e.g. how trapped H2O molecules rescue the interrupted PT-pathway. These features provide conclusive evidence that the targeted positions are indeed vital for catalytic proton-transfer. [FeFe]-hydrogenases catalyze H2-evolution and -oxidation at very high turnover-rates. Here the authors provide experimental evidence for the proposed proton-transfer (PT) pathway by kinetically, spectroscopically, and crystallographically characterizing eleven mutants from the two [FeFe]-hydrogenases CpI and HydA1.
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Affiliation(s)
- Jifu Duan
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Moritz Senger
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Julian Esselborn
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Vera Engelbrecht
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Florian Wittkamp
- Department of Chemistry and Biochemistry, Inorganic Chemistry Ι, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Ulf-Peter Apfel
- Department of Chemistry and Biochemistry, Inorganic Chemistry Ι, Ruhr-Universität Bochum, 44801, Bochum, Germany.,Fraunhofer UMSICHT, Osterfelder Straße, 346047, Oberhausen, Germany
| | - Eckhard Hofmann
- Department of Biophysics, Protein Crystallography, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Thomas Happe
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany.
| | - Martin Winkler
- Department of Plant Biochemistry, Photobiotechnology, Ruhr-Universität Bochum, 44801, Bochum, Germany.
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Abstract
Over the past two decades, the bioinorganic chemistry of hydrogenases has attracted much interest from basic and applied research. Hydrogenases are highly efficient metalloenzymes that catalyze the reversible reduction of protons to molecular hydrogen (H2) in all domains of life. Their iron- and nickel-based cofactors represent promising blueprints for the design of biomimetic, synthetic catalysts. In this Account, we address the molecular proceedings of hydrogen turnover with [FeFe]-hydrogenases. The active site cofactor of [FeFe]-hydrogenases ("H-cluster") comprises a unique diiron complex linked to a [4Fe-4S] cluster via a single cysteine. Since it was discovered that a synthetic analogue of the diiron site can be incorporated into apoprotein in vitro to yield active enzyme, significant progress has been made toward a comprehensive understanding of hydrogenase catalysis. The diiron site carries three to four carbon monoxide (CO) and two cyanide (CN-) ligands that give rise to intense infrared (IR) absorption bands. These bands are sensitive reporters of the electron density across the H-cluster, which can be addressed by infrared spectroscopy to follow redox and protonation changes at the cofactor. Synthetic variation of the metal-bridging dithiolate ligand at the diiron site, as well as site-directed mutagenesis of amino acids, provides access to the proton pathways toward the cofactor. Quantum chemical calculations are employed to specifically assign IR bands to vibrational modes of the diatomic ligands and yield refined H-cluster geometries. Here, we provide an overview of recent research on [FeFe]-hydrogenases with emphasis on experimental and computational IR studies. We describe advances in attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) and protein film electrochemistry, as well as density functional theory (DFT) calculations. Key cofactor species are discussed in terms of molecular geometry, redox state, and protonation. Isotope editing is introduced as a tool to evaluate the cofactor geometry beyond the limits of protein crystallography. In particular, the role of proton-coupled electron transfer (PCET) in the generation of catalytically relevant redox species is addressed. We propose that site-selective protonation of the H-cluster biases surplus electrons either to the [4Fe-4S] cluster or to the diiron site. Protonation of the [4Fe-4S] cluster prevents premature reduction at the diiron site and stabilizes a reactive, terminal hydride. The observed H-cluster species are assigned to rapid H2 conversion or to reactions possibly involved in activity regulation and cellular H2 sensing. In the catalytic cycle of [FeFe]-hydrogenases, an H-cluster geometry is preserved that features a bridging CO ligand. PCET levels the redox potential for two steps of sequential cofactor reduction. The concept of consecutive PCET at a geometrically inert cofactor with tight control of electron and proton localization may inspire the design of a novel generation of biomimetic catalysts for the production of H2 as a fuel.
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Affiliation(s)
- Michael Haumann
- Department of Physics, Biophysics of Metalloenzymes, Freie Universität Berlin, 14195 Berlin, Germany
| | - Sven T. Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
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Rao G, Britt RD. Electronic Structure of Two Catalytic States of the [FeFe] Hydrogenase H-Cluster As Probed by Pulse Electron Paramagnetic Resonance Spectroscopy. Inorg Chem 2018; 57:10935-10944. [PMID: 30106575 DOI: 10.1021/acs.inorgchem.8b01557] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The active site of the [FeFe] hydrogenase (HydA1), the H-cluster, is a 6-Fe cofactor that contains CO and CN- ligands. It undergoes several different oxidation and protonation state changes in its catalytic cycle to metabolize H2. Among them, the well-known Hox state and the recently identified Hhyd state are thought to be directly involved in H2 activation and evolution, and they are both EPR active with net spin S = 1/2. Herein, we report the pulse electronic paramagnetic spectroscopic investigation of these two catalytic states in Chlamydomonas reinhardtii HydA1 ( CrHydA1). Using an in vitro biosynthetic maturation approach, we site-specifically installed 13C into the CO or CN- ligands and 57Fe into the [2Fe]H subcluster of the H-cluster in order to measure the hyperfine couplings to these magnetic nuclei. For Hox, we measured 13C hyperfine couplings (13CO aiso of 25.5, 5.8, and 4.5 MHz) corresponding to all three CO ligands in the H-cluster. We also observed two 57Fe hyperfine couplings (57Fe aiso of ∼17 and 5.7 MHz) arising from the two Fe atoms in the [2Fe]H subcluster. For Hhyd, we only observed two distinct 13CO hyperfine interactions (13CO aiso of 0.16 and 0.08 MHz) and only one for 13CN- (13CN aiso of 0.16 MHz); the couplings to the 13CO/13CN- on the distal Fe of [2Fe]H may be too small to detect. We also observed a very small (<0.3 MHz) 57Fe HFI from the labeled [2Fe]H subcluster and four 57Fe HFI from the labeled [4Fe-4S]H subcluster (57Fe aiso of 7.2, 16.6, 28.2, and 35.3 MHz). These hyperfine coupling constants are consistent with the previously proposed electronic structure of the H-cluster at both Hox and Hhyd states and provide a basis for more detailed analysis.
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Affiliation(s)
- Guodong Rao
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - R David Britt
- Department of Chemistry , University of California , Davis , California 95616 , United States
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55
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Pham CC, Mulder DW, Pelmenschikov V, King PW, Ratzloff MW, Wang H, Mishra N, Alp EE, Zhao J, Hu MY, Tamasaku K, Yoda Y, Cramer SP. Terminal Hydride Species in [FeFe]-Hydrogenases Are Vibrationally Coupled to the Active Site Environment. Angew Chem Int Ed Engl 2018; 57:10605-10609. [PMID: 29923293 PMCID: PMC6812543 DOI: 10.1002/anie.201805144] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Indexed: 01/01/2023]
Abstract
A combination of nuclear resonance vibrational spectroscopy (NRVS), FTIR spectroscopy, and DFT calculations was used to observe and characterize Fe-H/D bending modes in CrHydA1 [FeFe]-hydrogenase Cys-to-Ser variant C169S. Mutagenesis of cysteine to serine at position 169 changes the functional group adjacent to the H-cluster from a -SH to -OH, thus altering the proton transfer pathway. The catalytic activity of C169S is significantly reduced compared to that of native CrHydA1, presumably owing to less efficient proton transfer to the H-cluster. This mutation enabled effective capture of a hydride/deuteride intermediate and facilitated direct detection of the Fe-H/D normal modes. We observed a significant shift to higher frequency in an Fe-H bending mode of the C169S variant, as compared to previous findings with reconstituted native and oxadithiolate (ODT)-substituted CrHydA1. On the basis of DFT calculations, we propose that this shift is caused by the stronger interaction of the -OH group of C169S with the bridgehead -NH- moiety of the active site, as compared to that of the -SH group of C169 in the native enzyme.
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Affiliation(s)
- Cindy C. Pham
- Department of Chemistry, UC Davis, One Shields Ave, Davis, CA 95616, USA
| | - David W. Mulder
- National Renewable Energy Laboratory, 15013 Denver W. Pkwy., Golden, CO 80401, USA
| | - Vladimir Pelmenschikov
- Institut für Chemie, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany
| | - Paul W. King
- National Renewable Energy Laboratory, 15013 Denver W. Pkwy., Golden, CO 80401, USA
| | - Michael W. Ratzloff
- National Renewable Energy Laboratory, 15013 Denver W. Pkwy., Golden, CO 80401, USA
| | - Hongxin Wang
- Department of Chemistry, UC Davis, One Shields Ave, Davis, CA 95616, USA
| | - Nakul Mishra
- Department of Chemistry, UC Davis, One Shields Ave, Davis, CA 95616, USA
| | - Esen E. Alp
- Building 401, Argonne National Laboratory, 9700 Cass Ave, Lemont, IL 60439, USA
| | - Jiyong Zhao
- Building 401, Argonne National Laboratory, 9700 Cass Ave, Lemont, IL 60439, USA
| | - Michael Y. Hu
- Building 401, Argonne National Laboratory, 9700 Cass Ave, Lemont, IL 60439, USA
| | - Kenji Tamasaku
- JASRI, SPring-8, 1-1-1 Kouto, Mizauki-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Yoshitaka Yoda
- JASRI, SPring-8, 1-1-1 Kouto, Mizauki-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Stephen P. Cramer
- Department of Chemistry, UC Davis, One Shields Ave, Davis, CA 95616, USA
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Pham CC, Mulder DW, Pelmenschikov V, King PW, Ratzloff MW, Wang H, Mishra N, Alp EE, Zhao J, Hu MY, Tamasaku K, Yoda Y, Cramer SP. Terminal Hydride Species in [FeFe]‐Hydrogenases Are Vibrationally Coupled to the Active Site Environment. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Cindy C. Pham
- Department of Chemistry UC Davis One Shields Ave Davis CA 95616 USA
| | - David W. Mulder
- National Renewable Energy Laboratory 15013 Denver W. Pkwy. Golden CO 80401 USA
| | - Vladimir Pelmenschikov
- Institut für Chemie Technische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Paul W. King
- National Renewable Energy Laboratory 15013 Denver W. Pkwy. Golden CO 80401 USA
| | - Michael W. Ratzloff
- National Renewable Energy Laboratory 15013 Denver W. Pkwy. Golden CO 80401 USA
| | - Hongxin Wang
- Department of Chemistry UC Davis One Shields Ave Davis CA 95616 USA
| | - Nakul Mishra
- Department of Chemistry UC Davis One Shields Ave Davis CA 95616 USA
| | - Esen E. Alp
- Building 401 Argonne National Laboratory 9700 Cass Ave Lemont IL 60439 USA
| | - Jiyong Zhao
- Building 401 Argonne National Laboratory 9700 Cass Ave Lemont IL 60439 USA
| | - Michael Y. Hu
- Building 401 Argonne National Laboratory 9700 Cass Ave Lemont IL 60439 USA
| | - Kenji Tamasaku
- JASRI SPring-8 1-1-1 Kouto, Mizauki-cho Sayo-gun Hyogo 679-5198 Japan
| | - Yoshitaka Yoda
- JASRI SPring-8 1-1-1 Kouto, Mizauki-cho Sayo-gun Hyogo 679-5198 Japan
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57
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Rodríguez-Maciá P, Reijerse EJ, van Gastel M, DeBeer S, Lubitz W, Rüdiger O, Birrell JA. Sulfide Protects [FeFe] Hydrogenases From O 2. J Am Chem Soc 2018; 140:9346-9350. [PMID: 30008217 DOI: 10.1021/jacs.8b04339] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[FeFe] hydrogenases catalyze proton reduction and hydrogen oxidation with high rates and efficiency under physiological conditions, but are highly oxygen sensitive. The [FeFe] hydrogenase from Desulfovibrio desulfuricans ( DdHydAB) can be purified under air in an oxygen stable inactive state Hoxair. The formation of the Hoxair state in vitro allows the handling of hydrogenases in air, making their implementation in biotechnological applications more feasible. Here, we report a simple and robust protocol for the formation of the Hoxair state in DdHydAB and the [FeFe] hydrogenase from Chlamydomonas reinhardtii, which is based on high potential inactivation in the presence of sulfide.
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Affiliation(s)
- Patricia Rodríguez-Maciá
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim an der Ruhr , Germany
| | - Edward J Reijerse
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim an der Ruhr , Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , D-45470 Mülheim an der Ruhr , Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim an der Ruhr , Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim an der Ruhr , Germany
| | - Olaf Rüdiger
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim an der Ruhr , Germany
| | - James A Birrell
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim an der Ruhr , Germany
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58
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Pelmenschikov V, Gee LB, Wang H, MacLeod KC, McWilliams SF, Skubi KL, Cramer SP, Holland PL. High-Frequency Fe-H Vibrations in a Bridging Hydride Complex Characterized by NRVS and DFT. Angew Chem Int Ed Engl 2018; 57:9367-9371. [PMID: 29847703 DOI: 10.1002/anie.201804601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Indexed: 11/10/2022]
Abstract
High-spin iron species with bridging hydrides have been detected in species trapped during nitrogenase catalysis, but there are few general methods of evaluating Fe-H bonds in high-spin multinuclear iron systems. An 57 Fe nuclear resonance vibrational spectroscopy (NRVS) study on an Fe(μ-H)2 Fe model complex reveals Fe-H stretching vibrations for bridging hydrides at frequencies greater than 1200 cm-1 . These isotope-sensitive vibrational bands are not evident in infrared (IR) spectra, showing the power of NRVS for identifying hydrides in this high-spin iron system. Complementary density functional theory (DFT) calculations elucidate the normal modes of the rhomboidal iron hydride core.
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Affiliation(s)
| | - Leland B Gee
- Department of Chemistry, University of California, Davis, CA, 95616, USA.,Current Address: Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
| | - Hongxin Wang
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - K Cory MacLeod
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | | | - Kazimer L Skubi
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Stephen P Cramer
- Department of Chemistry, University of California, Davis, CA, 95616, USA
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59
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Pelmenschikov V, Gee LB, Wang H, MacLeod KC, McWilliams SF, Skubi KL, Cramer SP, Holland PL. High-Frequency Fe-H Vibrations in a Bridging Hydride Complex Characterized by NRVS and DFT. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804601] [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)
| | - Leland B. Gee
- Department of Chemistry; University of California; Davis CA 95616 USA
- Current Address: Department of Chemistry; Stanford University; Stanford CA 94305 USA
| | - Hongxin Wang
- Department of Chemistry; University of California; Davis CA 95616 USA
| | - K. Cory MacLeod
- Department of Chemistry; Yale University; New Haven CT 06520 USA
| | | | - Kazimer L. Skubi
- Department of Chemistry; Yale University; New Haven CT 06520 USA
| | - Stephen P. Cramer
- Department of Chemistry; University of California; Davis CA 95616 USA
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60
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Ratzloff MW, Artz JH, Mulder DW, Collins RT, Furtak TE, King PW. CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI. J Am Chem Soc 2018; 140:7623-7628. [PMID: 29792026 DOI: 10.1021/jacs.8b03072] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The [FeFe]-hydrogenases ([FeFe] H2ases) catalyze reversible H2 activation at the H-cluster, which is composed of a [4Fe-4S]H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe]H) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H2 bond activation have been proposed. We have examined this question in the [FeFe] H2ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of Hox led to formation of HredH+ ([4Fe-4S]H2+-FeI-FeI) and Hred' ([4Fe-4S]H1+-FeII-FeI), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe]H. Similar μ-CO IR modes were also identified for HredH+ of the [FeFe] H2ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, Hhyd. Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed HredH+ was converted to Hhyd. Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of Hhyd and appearance of Hox, consistent with enzymatic turnover and H2 formation. The results show for CaI that the μ-CO of [2Fe]H remains bridging for all of the "Hred" states and that HredH+ is on pathway to Hhyd and H2 evolution in the catalytic mechanism. These results provide a blueprint for designing small molecule catalytic analogs.
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Affiliation(s)
- Michael W Ratzloff
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Jacob H Artz
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - David W Mulder
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Reuben T Collins
- Physics Department , Colorado School of Mines , Golden , Colorado 80401 , United States
| | - Thomas E Furtak
- Physics Department , Colorado School of Mines , Golden , Colorado 80401 , United States
| | - Paul W King
- Biosciences Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
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61
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Taheri A, Carr CR, Berben LA. Electrochemical Methods for Assessing Kinetic Factors in the Reduction of CO2 to Formate: Implications for Improving Electrocatalyst Design. ACS Catal 2018. [DOI: 10.1021/acscatal.8b01799] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Atefeh Taheri
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Cody R. Carr
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Louise A. Berben
- Department of Chemistry, University of California, Davis, California 95616, United States
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62
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Spectroscopic investigations of a semi-synthetic [FeFe] hydrogenase with propane di-selenol as bridging ligand in the binuclear subsite: comparison to the wild type and propane di-thiol variants. J Biol Inorg Chem 2018; 23:481-491. [PMID: 29627860 PMCID: PMC5940705 DOI: 10.1007/s00775-018-1558-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/30/2018] [Indexed: 11/25/2022]
Abstract
[FeFe] Hydrogenases catalyze the reversible conversion of H2 into electrons and protons. Their catalytic site, the H-cluster, contains a generic [4Fe–4S]H cluster coupled to a [2Fe]H subsite [Fe2(ADT)(CO)3(CN)2]2−, ADT = µ(SCH2)2NH. Heterologously expressed [FeFe] hydrogenases (apo-hydrogenase) lack the [2Fe]H unit, but this can be incorporated through artificial maturation with a synthetic precursor [Fe2(ADT)(CO)4(CN)2]2−. Maturation with a [2Fe] complex in which the essential ADT amine moiety has been replaced by CH2 (PDT = propane-dithiolate) results in a low activity enzyme with structural and spectroscopic properties similar to those of the native enzyme, but with simplified redox behavior. Here, we study the effect of sulfur-to-selenium (S-to-Se) substitution in the bridging PDT ligand incorporated in the [FeFe] hydrogenase HydA1 from Chlamydomonas reinhardtii using magnetic resonance (EPR, NMR), FTIR and spectroelectrochemistry. The resulting HydA1-PDSe enzyme shows the same redox behavior as the parent HydA1-PDT. In addition, a state is observed in which extraneous CO is bound to the open coordination site of the [2Fe]H unit. This state was previously observed only in the native enzyme HydA1-ADT and not in HydA1-PDT. The spectroscopic features and redox behavior of HydA1-PDSe, resulting from maturation with [Fe2(PDSe)(CO)4(CN)2]2−, are discussed in terms of spin and charge density shifts and provide interesting insight into the electronic structure of the H-cluster. We also studied the effect of S-to-Se substitution in the [4Fe–4S] subcluster. The reduced form of HydA1 containing only the [4Fe–4Se]H cluster shows a characteristic S = 7/2 spin state which converts back into the S = 1/2 spin state upon maturation with a [2Fe]–PDT/ADT complex.
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63
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Sommer C, Richers CP, Lubitz W, Rauchfuss TB, Reijerse EJ. A [RuRu] Analogue of an [FeFe]-Hydrogenase Traps the Key Hydride Intermediate of the Catalytic Cycle. Angew Chem Int Ed Engl 2018; 57:5429-5432. [PMID: 29577535 DOI: 10.1002/anie.201801914] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Indexed: 12/15/2022]
Abstract
The active site of the [FeFe]-hydrogenases features a binuclear [2Fe]H sub-cluster that contains a unique bridging amine moiety close to an exposed iron center. Heterolytic splitting of H2 results in the formation of a transient terminal hydride at this iron site, which, however is difficult to stabilize. We show that the hydride intermediate forms immediately when [2Fe]H is replaced with [2Ru]H analogues through artificial maturation. Outside the protein, the [2Ru]H analogues form bridging hydrides, which rearrange to terminal hydrides after insertion into the apo-protein. H/D exchange of the hydride only occurs for [2Ru]H analogues containing the bridging amine moiety.
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Affiliation(s)
- Constanze Sommer
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Casseday P Richers
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Thomas B Rauchfuss
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Edward J Reijerse
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
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64
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Sommer C, Richers CP, Lubitz W, Rauchfuss TB, Reijerse EJ. A [RuRu] Analogue of an [FeFe]-Hydrogenase Traps the Key Hydride Intermediate of the Catalytic Cycle. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201801914] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Constanze Sommer
- Max-Planck-Institut für Chemische Energiekonversion; Stiftstrasse 34-36 45470 Mülheim an der Ruhr Germany
| | - Casseday P. Richers
- School of Chemical Sciences; University of Illinois at Urbana-Champaign; 600 S. Goodwin Ave. Urbana IL 61801 USA
| | - Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion; Stiftstrasse 34-36 45470 Mülheim an der Ruhr Germany
| | - Thomas B. Rauchfuss
- School of Chemical Sciences; University of Illinois at Urbana-Champaign; 600 S. Goodwin Ave. Urbana IL 61801 USA
| | - Edward J. Reijerse
- Max-Planck-Institut für Chemische Energiekonversion; Stiftstrasse 34-36 45470 Mülheim an der Ruhr Germany
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Rumpel S, Sommer C, Reijerse E, Farès C, Lubitz W. Direct Detection of the Terminal Hydride Intermediate in [FeFe] Hydrogenase by NMR Spectroscopy. J Am Chem Soc 2018. [PMID: 29521088 DOI: 10.1021/jacs.8b00459] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydride state intermediates are known to occur in various hydrogen conversion enzymes, including the highly efficient [FeFe] hydrogenases. The intermediate state involving a terminal iron-bound hydride has been recognized as crucial for the catalytic mechanism, but its occurrence has up to now eluded unequivocal proof under (near) physiological conditions. Here we show that the terminal hydride in the [FeFe] hydrogenase from Chlamydomonas reinhardtii can be directly detected using solution 1H NMR spectroscopy at room temperature, opening new avenues for detailed in situ investigations under catalytic conditions.
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Affiliation(s)
- Sigrun Rumpel
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Constanze Sommer
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Edward Reijerse
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Christophe Farès
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm Platz 1 , 45470 Mülheim an der Ruhr , Germany
| | - Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36 , 45470 Mülheim an der Ruhr , Germany
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66
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Carlson MR, Gray DL, Richers CP, Wang W, Zhao PH, Rauchfuss TB, Pelmenschikov V, Pham CC, Gee LB, Wang H, Cramer SP. Sterically Stabilized Terminal Hydride of a Diiron Dithiolate. Inorg Chem 2018; 57:1988-2001. [PMID: 29384371 DOI: 10.1021/acs.inorgchem.7b02903] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The kinetically robust hydride [t-HFe2(Me2pdt)(CO)2(dppv)2]+ ([t-H1]+) (Me2pdt2- = Me2C(CH2S-)2; dppv = cis-1,2-C2H2(PPh2)2) and related derivatives were prepared with 57Fe enrichment for characterization by NMR, FT-IR, and NRVS. The experimental results were rationalized using DFT molecular modeling and spectral simulations. The spectroscopic analysis was aimed at supporting assignments of Fe-H vibrational spectra as they relate to recent measurements on [FeFe]-hydrogenase enzymes. The combination of bulky Me2pdt2- and dppv ligands stabilizes the terminal hydride with respect to its isomerization to the 5-16 kcal/mol more stable bridging hydride ([μ-H1]+) with t1/2(313.3 K) = 19.3 min. In agreement with the nOe experiments, the calculations predict that one methyl group in [t-H1]+ interacts with the hydride with a computed CH···HFe distance of 1.7 Å. Although [t-H571]+ exhibits multiple NRVS features in the 720-800 cm-1 region containing the bending Fe-H modes, the deuterated [t-D571]+ sample exhibits a unique Fe-D/CO band at ∼600 cm-1. In contrast, the NRVS spectra for [μ-H571]+ exhibit weaker bands near 670-700 cm-1 produced by the Fe-H-Fe wagging modes coupled to Me2pdt2- and dppv motions.
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Affiliation(s)
- Michaela R Carlson
- School of Chemical Sciences, University of Illinois , Urbana, Illinois 61801, United States
| | - Danielle L Gray
- School of Chemical Sciences, University of Illinois , Urbana, Illinois 61801, United States
| | - Casseday P Richers
- School of Chemical Sciences, University of Illinois , Urbana, Illinois 61801, United States
| | - Wenguang Wang
- School of Chemical Sciences, University of Illinois , Urbana, Illinois 61801, United States
| | - Pei-Hua Zhao
- School of Chemical Sciences, University of Illinois , Urbana, Illinois 61801, United States
| | - Thomas B Rauchfuss
- School of Chemical Sciences, University of Illinois , Urbana, Illinois 61801, United States
| | | | - Cindy C Pham
- Department of Chemistry, University of California , Davis, California 95616, United States
| | - Leland B Gee
- Department of Chemistry, University of California , Davis, California 95616, United States
| | - Hongxin Wang
- Department of Chemistry, University of California , Davis, California 95616, United States
| | - Stephen P Cramer
- Department of Chemistry, University of California , Davis, California 95616, United States
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Rumpel S, Ravera E, Sommer C, Reijerse E, Farès C, Luchinat C, Lubitz W. 1H NMR Spectroscopy of [FeFe] Hydrogenase: Insight into the Electronic Structure of the Active Site. J Am Chem Soc 2018; 140:131-134. [PMID: 29211457 PMCID: PMC5765528 DOI: 10.1021/jacs.7b11196] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The [FeFe] hydrogenase
HydA1 from Chlamydomonas reinhardtii has been studied
using 1H NMR spectroscopy identifying
the paramagnetically shifted 1H resonances associated with
both the [4Fe-4S]H and the
[2Fe]H subclusters of the active site “H-cluster”.
The signal pattern of the unmaturated HydA1 containing only [4Fe-4S]H is reminiscent of bacterial-type ferredoxins. The spectra
of maturated HydA1, with a complete H-cluster in the active Hox and the CO-inhibited Hox–CO state, reveal
additional upfield and downfield shifted 1H resonances
originating from the four methylene protons of the azadithiolate ligand
in the [2Fe]H subsite. The two axial protons are affected
by positive spin density, while the two equatorial protons experience
negative spin density. These protons can be used as important probes
sensing the effects of ligand-binding to the catalytic site of the
H-cluster.
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Affiliation(s)
- Sigrun Rumpel
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Enrico Ravera
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center (CERM), University of Florence and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP) , Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Constanze Sommer
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Edward Reijerse
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Christophe Farès
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Claudio Luchinat
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center (CERM), University of Florence and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP) , Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
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68
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Wittkamp F, Senger M, Stripp ST, Apfel UP. [FeFe]-Hydrogenases: recent developments and future perspectives. Chem Commun (Camb) 2018; 54:5934-5942. [DOI: 10.1039/c8cc01275j] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
[FeFe]-Hydrogenases are the most efficient enzymes for catalytic hydrogen turnover.
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Affiliation(s)
- F. Wittkamp
- Faculty of Chemistry and Biochemistry
- Ruhr-Universität Bochum
- 44801 Bochum
- Germany
| | - M. Senger
- Department of Physics
- Freie Universität Berlin
- 1495 Berlin
- Germany
| | - S. T. Stripp
- Department of Physics
- Freie Universität Berlin
- 1495 Berlin
- Germany
| | - U.-P. Apfel
- Faculty of Chemistry and Biochemistry
- Ruhr-Universität Bochum
- 44801 Bochum
- Germany
- Fraunhofer UMSICHT
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