1
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Soualmia F, Cherrier MV, Chauviré T, Mauger M, Tatham P, Guillot A, Guinchard X, Martin L, Amara P, Mouesca JM, Daghmoum M, Benjdia A, Gambarelli S, Berteau O, Nicolet Y. Radical S-Adenosyl-l-Methionine Enzyme PylB: A C-Centered Radical to Convert l-Lysine into (3 R)-3-Methyl-d-Ornithine. J Am Chem Soc 2024; 146:6493-6505. [PMID: 38426440 DOI: 10.1021/jacs.3c03747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
PylB is a radical S-adenosyl-l-methionine (SAM) enzyme predicted to convert l-lysine into (3R)-3-methyl-d-ornithine, a precursor in the biosynthesis of the 22nd proteogenic amino acid pyrrolysine. This protein highly resembles that of the radical SAM tyrosine and tryptophan lyases, which activate their substrate by abstracting a H atom from the amino-nitrogen position. Here, combining in vitro assays, analytical methods, electron paramagnetic resonance spectroscopy, and theoretical methods, we demonstrated that instead, PylB activates its substrate by abstracting a H atom from the Cγ position of l-lysine to afford the radical-based β-scission. Strikingly, we also showed that PylB catalyzes the reverse reaction, converting (3R)-3-methyl-d-ornithine into l-lysine and using catalytic amounts of the 5'-deoxyadenosyl radical. Finally, we identified significant in vitro production of 5'-thioadenosine, an unexpected shunt product that we propose to result from the quenching of the 5'-deoxyadenosyl radical species by the nearby [Fe4S4] cluster.
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Affiliation(s)
- Feryel Soualmia
- Université Paris-Saclay, Micalis Institute, ChemSyBio, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Mickael V Cherrier
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Timothée Chauviré
- Univ. Grenoble Alpes, CEA, CNRS, IRIG-DIESE-SyMMES-CAMPE, F-38000 Grenoble, France
| | - Mickaël Mauger
- Université Paris-Saclay, Micalis Institute, ChemSyBio, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Philip Tatham
- Université Paris-Saclay, Micalis Institute, ChemSyBio, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Alain Guillot
- Université Paris-Saclay, Micalis Institute, ChemSyBio, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Xavier Guinchard
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France
| | - Lydie Martin
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Patricia Amara
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Jean-Marie Mouesca
- Univ. Grenoble Alpes, CEA, CNRS, IRIG-DIESE-SyMMES-CAMPE, F-38000 Grenoble, France
| | - Meriem Daghmoum
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France
| | - Alhosna Benjdia
- Université Paris-Saclay, Micalis Institute, ChemSyBio, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Serge Gambarelli
- Univ. Grenoble Alpes, CEA, CNRS, IRIG-DIESE-SyMMES-CAMPE, F-38000 Grenoble, France
| | - Olivier Berteau
- Université Paris-Saclay, Micalis Institute, ChemSyBio, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France
| | - Yvain Nicolet
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
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2
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Omeiri J, Martin L, Usclat A, Cherrier MV, Nicolet Y. Maturation of the [FeFe]-Hydrogenase: Direct Transfer of the (κ 3 -cysteinate)Fe II (CN)(CO) 2 Complex B from HydG to HydE. Angew Chem Int Ed Engl 2023; 62:e202314819. [PMID: 37962296 DOI: 10.1002/anie.202314819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/15/2023]
Abstract
[FeFe]-hydrogenases efficiently catalyze the reversible oxidation of molecular hydrogen. Their prowess stems from the intricate H-cluster, combining a [Fe4 S4 ] center with a binuclear iron center ([2Fe]H ). In the latter, each iron atom is coordinated by a CO and CN ligand, connected by a CO and an azadithiolate ligand. The synthesis of this active site involves a unique multiprotein assembly, featuring radical SAM proteins HydG and HydE. HydG initiates the transformation of L-tyrosine into cyanide and carbon monoxide to generate complex B, which is subsequently transferred to HydE to continue the biosynthesis of the [2Fe]H -subcluster. Due to its instability, complex B isolation for structural or spectroscopic characterization has been elusive thus far. Nevertheless, the use of a biomimetic analogue of complex B allowed circumvention of the need for the HydG protein during in vitro functional investigations, implying a similar structure for complex B. Herein, we used the HydE protein as a nanocage to encapsulate and stabilize the complex B product generated by HydG. Using X-ray crystallography, we successfully determined its structure at 1.3 Å resolution. Furthermore, we demonstrated that complex B is directly transferred from HydG to HydE, thus not being released into the solution post-synthesis, highlighting a transient interaction between the two proteins.
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Affiliation(s)
- Juneina Omeiri
- Univ. Grenoble-Alpes, CEA, CNRS, IBS, Metalloproteins Unit, 38000, Grenoble, France
| | - Lydie Martin
- Univ. Grenoble-Alpes, CEA, CNRS, IBS, Metalloproteins Unit, 38000, Grenoble, France
| | - Anthony Usclat
- Univ. Grenoble-Alpes, CEA, CNRS, IBS, Metalloproteins Unit, 38000, Grenoble, France
| | - Mickael V Cherrier
- Univ. Grenoble-Alpes, CEA, CNRS, IBS, Metalloproteins Unit, 38000, Grenoble, France
| | - Yvain Nicolet
- Univ. Grenoble-Alpes, CEA, CNRS, IBS, Metalloproteins Unit, 38000, Grenoble, France
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3
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Balci B, O'Neill RD, Shepard EM, Pagnier A, Marlott A, Mock MT, Broderick WE, Broderick JB. Semisynthetic maturation of [FeFe]-hydrogenase using [Fe 2(μ-SH) 2(CN) 2(CO) 4] 2-: key roles for HydF and GTP. Chem Commun (Camb) 2023. [PMID: 37376915 DOI: 10.1039/d3cc02169f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Here we describe maturation of the [FeFe]-hydrogenase from its [4Fe-4S]-bound precursor state by using the synthetic complex [Fe2(μ-SH)2(CN)2(CO)4]2- together with HydF and components of the glycine cleavage system, but in the absence of the maturases HydE and HydG. This semisynthetic and fully-defined maturation provides new insights into the nature of H-cluster biosynthesis.
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Affiliation(s)
- Batuhan Balci
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Roark D O'Neill
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Eric M Shepard
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Adrien Pagnier
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Alexander Marlott
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Michael T Mock
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - William E Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Joan B Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
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4
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Abstract
Covering: up to 2022The report provides a broad approach to deciphering the evolution of coenzyme biosynthetic pathways. Here, these various pathways are analyzed with respect to the coenzymes required for this purpose. Coenzymes whose biosynthesis relies on a large number of coenzyme-mediated reactions probably appeared on the scene at a later stage of biological evolution, whereas the biosyntheses of pyridoxal phosphate (PLP) and nicotinamide (NAD+) require little additional coenzymatic support and are therefore most likely very ancient biosynthetic pathways.
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Affiliation(s)
- Andreas Kirschning
- Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, D-30167 Hannover, Germany.
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5
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Li Y, Kitadai N, Sekine Y, Kurokawa H, Nakano Y, Johnson-Finn K. Geoelectrochemistry-driven alteration of amino acids to derivative organics in carbonaceous chondrite parent bodies. Nat Commun 2022; 13:4893. [PMID: 35986003 PMCID: PMC9391434 DOI: 10.1038/s41467-022-32596-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 08/08/2022] [Indexed: 11/16/2022] Open
Abstract
A long-standing question regarding carbonaceous chondrites (CCs) is how the CCs’ organics were sourced and converted before and after the accretion of their parent bodies. Growing evidence shows that amino acid abundances in CCs decrease with an elongated aqueous alteration. However, the underlying chemical processes are unclear. If CCs’ parent bodies were water-rock differentiated, pH and redox gradients can drive electrochemical reactions by using H2 as an electron source. Here, we simulate such redox conditions and demonstrate that α-amino acids are electrochemically altered to monoamines and α-hydroxy acids on FeS and NiS catalysts at 25 °C. This conversion is consistent with their enrichment compared to amino acid analogs in heavily altered CCs. Our results thus suggest that H2 can be an important driver for organic evolution in water-rock differentiated CC parent bodies as well as the Solar System icy bodies that might possess similar pH and redox gradients. Researchers at Earth-Life Science Institute (ELSI) discovered a chemical process that can explain the very low amino acid abundances in aqueously altered carbonaceous chondrites, deepening our understanding on the Solar System chemical evolution.
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6
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L-tyrosine-bound ThiH structure reveals C-C bond break differences within radical SAM aromatic amino acid lyases. Nat Commun 2022; 13:2284. [PMID: 35477710 PMCID: PMC9046217 DOI: 10.1038/s41467-022-29980-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 04/05/2022] [Indexed: 11/08/2022] Open
Abstract
2-iminoacetate synthase ThiH is a radical S-adenosyl-L-methionine (SAM) L-tyrosine lyase and catalyzes the L-tyrosine Cα-Cβ bond break to produce dehydroglycine and p-cresol while the radical SAM L-tryptophan lyase NosL cleaves the L-tryptophan Cα-C bond to produce 3-methylindole-2-carboxylic acid. It has been difficult to understand the features that condition one C-C bond break over the other one because the two enzymes display significant primary structure similarities and presumably similar substrate-binding modes. Here, we report the crystal structure of L-tyrosine bound ThiH from Thermosinus carboxydivorans revealing an unusual protonation state of L-tyrosine upon binding. Structural comparison of ThiH with NosL and computational studies of the respective reactions they catalyze show that substrate activation is eased by tunneling effect and that subtle structural changes between the two enzymes affect, in particular, the hydrogen-atom abstraction by the 5´-deoxyadenosyl radical species, driving the difference in reaction specificity.
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7
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Britt RD, Tao L, Rao G, Chen N, Wang LP. Proposed Mechanism for the Biosynthesis of the [FeFe] Hydrogenase H-Cluster: Central Roles for the Radical SAM Enzymes HydG and HydE. ACS BIO & MED CHEM AU 2022; 2:11-21. [PMID: 35187536 PMCID: PMC8855341 DOI: 10.1021/acsbiomedchemau.1c00035] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 01/05/2023]
Abstract
Radical S-adenosylmethionine (radical SAM or rSAM) enzymes use their S-adenosylmethionine cofactor bound to a unique Fe of a [4Fe-4S] cluster to generate the "hot" 5'-deoxyadenosyl radical, which drives highly selective radical reactions via specific interactions with a given rSAM enzyme's substrate. This Perspective focuses on the two rSAM enzymes involved in the biosynthesis of the organometallic H-cluster of [FeFe] hydrogenases. We present here a detailed sequential model initiated by HydG, which lyses a tyrosine substrate via a 5'-deoxyadenosyl H atom abstraction from those amino acid's amino group, initially producing dehydroglycine and an oxidobenzyl radical. In this model, two successive radical cascade reactions lead ultimately to the formation of HydG's product, a mononuclear Fe organometallic complex: [Fe(II)(CN)(CO)2(cysteinate)]-, with the iron originating from a unique "dangler" Fe coordinated by a cysteine ligand providing a sulfur bridge to another [4Fe-4S] auxiliary cluster in the enzyme. In turn, in this model, [Fe(II)(CN)(CO)2(cysteinate)]- is the substrate for HydE, the second rSAM enzyme in the biosynthetic pathway, which activates this mononuclear organometallic unit for dimerization, forming a [Fe2S2(CO)4(CN)2] precursor to the [2Fe] H component of the H-cluster, requiring only the completion of the bridging azadithiolate (SCH2NHCH2S) ligand. This model is built upon a foundation of data that incorporates cell-free synthesis, isotope sensitive spectroscopies, and the selective use of synthetic complexes substituting for intermediates in the enzymatic "assembly line". We discuss controversies pertaining to this model and some remaining open issues to be addressed by future work.
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Affiliation(s)
- R David Britt
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Lizhi Tao
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Guodong Rao
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Nanhao Chen
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
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8
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Nicolet Y, Cherrier MV, Amara P. Radical SAM Enzymes and Metallocofactor Assembly: A Structural Point of View. ACS BIO & MED CHEM AU 2022; 2:36-52. [PMID: 37102176 PMCID: PMC10114646 DOI: 10.1021/acsbiomedchemau.1c00044] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This Review focuses on the structure-function relationship of radical S-adenosyl-l-methionine (SAM) enzymes involved in the assembly of metallocofactors corresponding to the active sites of [FeFe]-hydrogenase and nitrogenase [MoFe]-protein. It does not claim to correspond to an extensive review on the assembly machineries of these enzyme active sites, for which many good reviews are already available, but instead deals with the contribution of structural data to the understanding of their chemical mechanism (Buren et al. Chem. Rev.2020, 142 ( (25), ) 11006-11012; Britt et al. Chem. Sci.2020, 11 ( (38), ), 10313-10323). Hence, we will present the history and current knowledge about the radical SAM maturases HydE, HydG, and NifB as well as what, in our opinion, should be done in the near future to overcome the existing barriers in our understanding of this fascinating chemistry that intertwine organic radicals and organometallic complexes.
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Affiliation(s)
- Yvain Nicolet
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Mickael V. Cherrier
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Patricia Amara
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
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9
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Rao G, Chen N, Marchiori DA, Wang LP, Britt RD. Accumulation and Pulse Electron Paramagnetic Resonance Spectroscopic Investigation of the 4-Oxidobenzyl Radical Generated in the Radical S-Adenosyl-l-methionine Enzyme HydG. Biochemistry 2022; 61:107-116. [PMID: 34989236 DOI: 10.1021/acs.biochem.1c00619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The radical S-adenosyl-l-methionine (SAM) enzyme HydG cleaves tyrosine to generate CO and CN- ligands of the [FeFe] hydrogenase H-cluster, accompanied by the formation of a 4-oxidobenzyl radical (4-OB•), which is the precursor to the HydG p-cresol byproduct. Native HydG only generates a small amount of 4-OB•, limiting detailed electron paramagnetic resonance (EPR) spectral characterization beyond our initial EPR lineshape study employing various tyrosine isotopologues. Here, we show that the concentration of trapped 4-OB• is significantly increased in reactions using HydG variants, in which the "dangler Fe" to which CO and CN- bind is missing or substituted by a redox-inert Zn2+ ion. This allows for the detailed characterization of 4-OB• using high-field EPR and electron nuclear double resonance spectroscopy to extract its g-values and 1H/13C hyperfine couplings. These results are compared to density functional theory-predicted values of several 4-OB• models with different sizes and protonation states, with a best fit to the deprotonated radical anion configuration of 4-OB•. Overall, our results depict a clearer electronic structure of the transient 4-OB• radical and provide new insights into the radical SAM chemistry of HydG.
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Affiliation(s)
- Guodong Rao
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Nanhao Chen
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - David A Marchiori
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - R David Britt
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
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10
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Chen N, Rao G, Britt RD, Wang LP. Quantum Chemical Study of a Radical Relay Mechanism for the HydG-Catalyzed Synthesis of a Fe(II)(CO) 2(CN)cysteine Precursor to the H-Cluster of [FeFe] Hydrogenase. Biochemistry 2021; 60:3016-3026. [PMID: 34569243 DOI: 10.1021/acs.biochem.1c00379] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The [FeFe] hydrogenase catalyzes the redox interconversion of protons and H2 with a Fe-S "H-cluster" employing CO, CN, and azadithiolate ligands to two Fe centers. The biosynthesis of the H-cluster is a highly interesting reaction carried out by a set of Fe-S maturase enzymes called HydE, HydF, and HydG. HydG, a member of the radical S-adenosylmethionine (rSAM) family, converts tyrosine, cysteine, and Fe(II) into an organometallic Fe(II)(CO)2(CN)cysteine "synthon", which serves as the substrate for HydE. Although key aspects of the HydG mechanism have been experimentally determined via isotope-sensitive spectroscopic methods, other important mechanistic questions have eluded experimental determination. Here, we use computational quantum chemistry to refine the mechanism of the HydG catalytic reaction. We utilize quantum mechanics/molecular mechanics simulations to investigate the reactions at the canonical Fe-S cluster, where a radical cleavage of the tyrosine substrate takes place and proceeds through a relay of radical intermediates to form HCN and a COO•- radical anion. We then carry out a broken-symmetry density functional theory study of the reactions at the unusual five-iron auxiliary Fe-S cluster, where two equivalents of CN- and COOH• coordinate to the fifth "dangler iron" in a series of substitution and redox reactions that yield the synthon as the final product for further processing by HydE.
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Affiliation(s)
- Nanhao Chen
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Guodong Rao
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - R David Britt
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
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11
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Shepard EM, Impano S, Duffus BR, Pagnier A, Duschene KS, Betz JN, Byer AS, Galambas A, McDaniel EC, Watts H, McGlynn SE, Peters JW, Broderick WE, Broderick JB. HydG, the "dangler" iron, and catalytic production of free CO and CN -: implications for [FeFe]-hydrogenase maturation. Dalton Trans 2021; 50:10405-10422. [PMID: 34240096 PMCID: PMC9154046 DOI: 10.1039/d1dt01359a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The organometallic H-cluster of the [FeFe]-hydrogenase consists of a [4Fe-4S] cubane bridged via a cysteinyl thiolate to a 2Fe subcluster ([2Fe]H) containing CO, CN-, and dithiomethylamine (DTMA) ligands. The H-cluster is synthesized by three dedicated maturation proteins: the radical SAM enzymes HydE and HydG synthesize the non-protein ligands, while the GTPase HydF serves as a scaffold for assembly of [2Fe]H prior to its delivery to the [FeFe]-hydrogenase containing the [4Fe-4S] cubane. HydG uses l-tyrosine as a substrate, cleaving it to produce p-cresol as well as the CO and CN- ligands to the H-cluster, although there is some question as to whether these are formed as free diatomics or as part of a [Fe(CO)2(CN)] synthon. Here we show that Clostridium acetobutylicum (C.a.) HydG catalyzes formation of multiple equivalents of free CO at rates comparable to those for CN- formation. Free CN- is also formed in excess molar equivalents over protein. A g = 8.9 EPR signal is observed for C.a. HydG reconstituted to load the 5th "dangler" iron of the auxiliary [4Fe-4S][FeCys] cluster and is assigned to this "dangler-loaded" cluster state. Free CO and CN- formation and the degree of activation of [FeFe]-hydrogenase all occur regardless of dangler loading, but are increased 10-35% in the dangler-loaded HydG; this indicates the dangler iron is not essential to this process but may affect relevant catalysis. During HydG turnover in the presence of myoglobin, the g = 8.9 signal remains unchanged, indicating that a [Fe(CO)2(CN)(Cys)] synthon is not formed at the dangler iron. Mutation of the only protein ligand to the dangler iron, H272, to alanine nearly completely abolishes both free CO formation and hydrogenase activation, however results show this is not due solely to the loss of the dangler iron. In experiments with wild type and H272A HydG, and with different degrees of dangler loading, we observe a consistent correlation between free CO/CN- formation and hydrogenase activation. Taken in full, our results point to free CO/CN-, but not an [Fe(CO)2(CN)(Cys)] synthon, as essential species in hydrogenase maturation.
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Affiliation(s)
- Eric M Shepard
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Stella Impano
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Benjamin R Duffus
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Adrien Pagnier
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Kaitlin S Duschene
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Jeremiah N Betz
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Amanda S Byer
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Amanda Galambas
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Elizabeth C McDaniel
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Hope Watts
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Shawn E McGlynn
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - John W Peters
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99163, USA
| | - William E Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
| | - Joan B Broderick
- Department of Chemistry & Biochemistry, Montana State University, Bozeman, MT 59717, USA.
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12
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Rohac R, Martin L, Liu L, Basu D, Tao L, Britt RD, Rauchfuss TB, Nicolet Y. Crystal Structure of the [FeFe]-Hydrogenase Maturase HydE Bound to Complex-B. J Am Chem Soc 2021; 143:8499-8508. [PMID: 34048236 DOI: 10.1021/jacs.1c03367] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[FeFe]-hydrogenases use a unique organometallic complex, termed the H cluster, to reversibly convert H2 into protons and low-potential electrons. It can be best described as a [Fe4S4] cluster coupled to a unique [2Fe]H center where the reaction actually takes place. The latter corresponds to two iron atoms, each of which is bound by one CN- ligand and one CO ligand. The two iron atoms are connected by a unique azadithiolate molecule (-S-CH2-NH-CH2-S-) and an additional bridging CO. This [2Fe]H center is built stepwise thanks to the well-orchestrated action of maturating enzymes that belong to the Hyd machinery. Among them, HydG converts l-tyrosine into CO and CN- to produce a unique l-cysteine-Fe(CO)2CN species termed complex-B. Very recently, HydE was shown to perform radical-based chemistry using synthetic complex-B as a substrate. Here we report the high-resolution crystal structure that establishes the identity of the complex-B-bound HydE. By triggering the reaction prior to crystallization, we trapped a new five-coordinate Fe species, supporting the proposal that HydE performs complex modifications of complex-B to produce a monomeric "SFe(CO)2CN" precursor to the [2Fe]H center. Substrate access, product release, and intermediate transfer are also discussed.
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Affiliation(s)
- Roman Rohac
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Lydie Martin
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Liang Liu
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Debashis Basu
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Lizhi Tao
- Department of Chemistry, University of California-Davis, Davis, California 95616, United States
| | - R David Britt
- Department of Chemistry, University of California-Davis, Davis, California 95616, United States
| | - Thomas B Rauchfuss
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yvain Nicolet
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
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13
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Impano S, Yang H, Shepard EM, Swimley R, Pagnier A, Broderick WE, Hoffman BM, Broderick JB. S-Adenosyl-l-ethionine is a Catalytically Competent Analog of S-Adenosyl-l-methione (SAM) in the Radical SAM Enzyme HydG. Angew Chem Int Ed Engl 2021; 60:4666-4672. [PMID: 33935588 PMCID: PMC8081114 DOI: 10.1002/anie.202014337] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Indexed: 01/02/2023]
Abstract
Radical S-adenosyl-l-methionine (SAM) enzymes initiate biological radical reactions with the 5'-deoxyadenosyl radical (5'-dAdo•). A [4Fe-4S]+ cluster reductively cleaves SAM to form the Ω organometallic intermediate in which the 5'-deoxyadenosyl moiety is directly bound to the unique iron of the [4Fe-4S] cluster, with subsequent liberation of 5'-dAdo•. Here we present synthesis of the SAM analog S-adenosyl-l-ethionine (SAE) and show SAE is a mechanistically-equivalent SAM-alternative for HydG, both supporting enzymatic turnover of substrate tyrosine and forming the organometallic intermediate Ω. Photolysis of SAE bound to HydG forms an ethyl radical trapped in the active site. The ethyl radical withstands prolonged storage at 77 K and its EPR signal is only partially lost upon annealing at 100 K, making it significantly less reactive than the methyl radical formed by SAM photolysis. Upon annealing above 77K, the ethyl radical adds to the [4Fe-4S]2+ cluster, generating an ethyl-[4Fe-4S]3+ organometallic species termed ΩE.
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Affiliation(s)
- Stella Impano
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
| | - Hao Yang
- Department of Chemistry, Northwestern University, Evanston, IL. USA 60208
| | - Eric M Shepard
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
| | - Ryan Swimley
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
| | - Adrien Pagnier
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
| | - William E Broderick
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
| | - Brian M Hoffman
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
| | - Joan B Broderick
- Department of Chemistry & Biochemistry, ontana State University, ozeman, MT. USA. 59717
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14
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Impano S, Yang H, Shepard EM, Swimley R, Pagnier A, Broderick WE, Hoffman BM, Broderick JB. S
‐Adenosyl‐
l
‐ethionine is a Catalytically Competent Analog of
S
‐Adenosyl‐
l
‐methionine (SAM) in the Radical SAM Enzyme HydG. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Stella Impano
- Department of Chemistry & Biochemistry Montana State University Bozeman MT 59717 USA
| | - Hao Yang
- Department of Chemistry Northwestern University Evanston IL 60208 USA
| | - Eric M. Shepard
- Department of Chemistry & Biochemistry Montana State University Bozeman MT 59717 USA
| | - Ryan Swimley
- Department of Chemistry & Biochemistry Montana State University Bozeman MT 59717 USA
| | - Adrien Pagnier
- Department of Chemistry & Biochemistry Montana State University Bozeman MT 59717 USA
| | - William E. Broderick
- Department of Chemistry & Biochemistry Montana State University Bozeman MT 59717 USA
| | - Brian M. Hoffman
- Department of Chemistry Northwestern University Evanston IL 60208 USA
| | - Joan B. Broderick
- Department of Chemistry & Biochemistry Montana State University Bozeman MT 59717 USA
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15
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Britt RD, Rao G, Tao L. Bioassembly of complex iron-sulfur enzymes: hydrogenases and nitrogenases. Nat Rev Chem 2020; 4:542-549. [PMID: 33829110 PMCID: PMC8023223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nature uses multinuclear metal clusters to catalyse a number of important multielectron redox reactions. Examples that employ complex Fe-S clusters in catalysis include the Fe-Mo cofactor (FeMoco) of nitrogenase and its V and all-Fe variants, and the [FeFe] and [NiFe] hydrogenases. This Perspective begins with a focus on the catalytic H-cluster of [FeFe] hydrogenase, which is highly active in producing molecular H2. There has been much recent progress in characterizing the enzyme-catalysed assembly of the H-cluster, including information gleaned from spectroscopy combined with in vitro isotopic labelling of this cluster using chemical synthesis. We then compare the lessons learned from H-cluster biosynthesis to what is known about the bioassembly of the binuclear active site of [NiFe] hydrogenase and the nitrogenase active site cluster FeMoco.
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16
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17
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Tao L, Pattenaude SA, Joshi S, Begley TP, Rauchfuss TB, Britt RD. Radical SAM Enzyme HydE Generates Adenosylated Fe(I) Intermediates En Route to the [FeFe]-Hydrogenase Catalytic H-Cluster. J Am Chem Soc 2020; 142:10841-10848. [PMID: 32434327 PMCID: PMC7440672 DOI: 10.1021/jacs.0c03802] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The H-cluster of [FeFe]-hydrogenase consists of a [4Fe-4S]H-subcluster linked by a cysteinyl bridge to a unique organometallic [2Fe]H-subcluster assigned as the site of interconversion between protons and molecular hydrogen. This [2Fe]H-subcluster is assembled by a set of Fe-S maturase enzymes HydG, HydE and HydF. Here we show that the HydG product [FeII(Cys)(CO)2(CN)] synthon is the substrate of the radical SAM enzyme HydE, with the generated 5'-deoxyadenosyl radical attacking the cysteine S to form a C5'-S bond concomitant with reduction of the central low-spin Fe(II) to the Fe(I) oxidation state. This leads to the cleavage of the cysteine C3-S bond, producing a mononuclear [FeI(CO)2(CN)S] species that serves as the precursor to the dinuclear Fe(I)Fe(I) center of the [2Fe]H-subcluster. This work unveils the role played by HydE in the enzymatic assembly of the H-cluster and expands the scope of radical SAM enzyme chemistry.
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Affiliation(s)
- Lizhi Tao
- Department of Chemistry, University of California at Davis, Davis, California 95616, United States
| | - Scott A Pattenaude
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sumedh Joshi
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Tadhg P Begley
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Thomas B Rauchfuss
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - R David Britt
- Department of Chemistry, University of California at Davis, Davis, California 95616, United States
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18
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Adenosylation reactions catalyzed by the radical S-adenosylmethionine superfamily enzymes. Curr Opin Chem Biol 2020; 55:86-95. [DOI: 10.1016/j.cbpa.2020.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/22/2019] [Accepted: 01/15/2020] [Indexed: 01/23/2023]
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19
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Muraki N, Ishii K, Uchiyama S, Itoh SG, Okumura H, Aono S. Structural characterization of HypX responsible for CO biosynthesis in the maturation of NiFe-hydrogenase. Commun Biol 2019; 2:385. [PMID: 31646188 PMCID: PMC6802093 DOI: 10.1038/s42003-019-0631-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 09/20/2019] [Indexed: 12/20/2022] Open
Abstract
Several accessory proteins are required for the assembly of the metal centers in hydrogenases. In NiFe-hydrogenases, CO and CN- are coordinated to the Fe in the NiFe dinuclear cluster of the active center. Though these diatomic ligands are biosynthesized enzymatically, detail mechanisms of their biosynthesis remain unclear. Here, we report the structural characterization of HypX responsible for CO biosynthesis to assemble the active site of NiFe hydrogenase. CoA is constitutionally bound in HypX. Structural characterization of HypX suggests that the formyl-group transfer will take place from N10-formyl-THF to CoA to form formyl-CoA in the N-terminal domain of HypX, followed by decarbonylation of formyl-CoA to produce CO in the C-terminal domain though the direct experimental results are not available yet. The conformation of CoA accommodated in the continuous cavity connecting the N- and C-terminal domains will interconvert between the extended and the folded conformations for HypX catalysis.
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Affiliation(s)
- Norifumi Muraki
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Department of Structural Molecular Science, The Graduate University for Advanced Studies, 38 Nishogo-naka, Myodaiji-cho, Okazaki 444-8585 Japan
| | - Kentaro Ishii
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
| | - Susumu Uchiyama
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 Japan
| | - Satoru G. Itoh
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Department of Structural Molecular Science, The Graduate University for Advanced Studies, 38 Nishogo-naka, Myodaiji-cho, Okazaki 444-8585 Japan
| | - Hisashi Okumura
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Department of Structural Molecular Science, The Graduate University for Advanced Studies, 38 Nishogo-naka, Myodaiji-cho, Okazaki 444-8585 Japan
| | - Shigetoshi Aono
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787 Japan
- Department of Structural Molecular Science, The Graduate University for Advanced Studies, 38 Nishogo-naka, Myodaiji-cho, Okazaki 444-8585 Japan
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20
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The binuclear cluster of [FeFe] hydrogenase is formed with sulfur donated by cysteine of an [Fe(Cys)(CO) 2(CN)] organometallic precursor. Proc Natl Acad Sci U S A 2019; 116:20850-20855. [PMID: 31570604 DOI: 10.1073/pnas.1913324116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The enzyme [FeFe]-hydrogenase (HydA1) contains a unique 6-iron cofactor, the H-cluster, that has unusual ligands to an Fe-Fe binuclear subcluster: CN-, CO, and an azadithiolate (adt) ligand that provides 2 S bridges between the 2 Fe atoms. In cells, the H-cluster is assembled by a collection of 3 maturases: HydE and HydF, whose roles aren't fully understood, and HydG, which has been shown to construct a [Fe(Cys)(CO)2(CN)] organometallic precursor to the binuclear cluster. Here, we report the in vitro assembly of the H-cluster in the absence of HydG, which is functionally replaced by adding a synthetic [Fe(Cys)(CO)2(CN)] carrier in the maturation reaction. The synthetic carrier and the HydG-generated analog exhibit similar infrared spectra. The carrier allows HydG-free maturation to HydA1, whose activity matches that of the native enzyme. Maturation with 13CN-containing carrier affords 13CN-labeled enzyme as verified by electron paramagnetic resonance (EPR)/electron nuclear double-resonance spectra. This synthetic surrogate approach complements existing biochemical strategies and greatly facilitates the understanding of pathways involved in the assembly of the H-cluster. As an immediate demonstration, we clarify that Cys is not the source of the carbon and nitrogen atoms in the adt ligand using pulse EPR to target the magnetic couplings introduced via a 13C3,15N-Cys-labeled synthetic carrier. Parallel mass-spectrometry experiments show that the Cys backbone is converted to pyruvate, consistent with a cysteine role in donating S in forming the adt bridge. This mechanistic scenario is confirmed via maturation with a seleno-Cys carrier to form HydA1-Se, where the incorporation of Se was characterized by extended X-ray absorption fine structure spectroscopy.
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21
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Yang H, Impano S, Shepard EM, James CD, Broderick WE, Broderick JB, Hoffman BM. Photoinduced Electron Transfer in a Radical SAM Enzyme Generates an S-Adenosylmethionine Derived Methyl Radical. J Am Chem Soc 2019; 141:16117-16124. [PMID: 31509404 DOI: 10.1021/jacs.9b08541] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Radical SAM (RS) enzymes use S-adenosyl-l-methionine (SAM) and a [4Fe-4S] cluster to initiate a broad spectrum of radical transformations throughout all kingdoms of life. We report here that low-temperature photoinduced electron transfer from the [4Fe-4S]1+ cluster to bound SAM in the active site of the hydrogenase maturase RS enzyme, HydG, results in specific homolytic cleavage of the S-CH3 bond of SAM, rather than the S-C5' bond as in the enzyme-catalyzed (thermal) HydG reaction. This result is in stark contrast to a recent report in which photoinduced ET in the RS enzyme pyruvate formate-lyase activating enzyme cleaved the S-C5' bond to generate a 5'-deoxyadenosyl radical, and provides the first direct evidence for homolytic S-CH3 bond cleavage in a RS enzyme. Photoinduced ET in HydG generates a trapped •CH3 radical, as well as a small population of an organometallic species with an Fe-CH3 bond, denoted ΩM. The •CH3 radical is surprisingly found to exhibit rotational diffusion in the HydG active site at temperatures as low as 40 K, and is rapidly quenched: whereas 5'-dAdo• is stable indefinitely at 77 K, •CH3 quenches with a half-time of ∼2 min at this temperature. The rapid quenching and rotational/translational freedom of •CH3 shows that enzymes would be unable to harness this radical as a regio- and stereospecific H atom abstractor during catalysis, in contrast to the exquisite control achieved with the enzymatically generated 5'-dAdo•.
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Affiliation(s)
- Hao Yang
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Stella Impano
- Department of Chemistry & Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Eric M Shepard
- Department of Chemistry & Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Christopher D James
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - William E Broderick
- Department of Chemistry & Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Joan B Broderick
- Department of Chemistry & Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Brian M Hoffman
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
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22
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H-cluster assembly intermediates built on HydF by the radical SAM enzymes HydE and HydG. J Biol Inorg Chem 2019; 24:783-792. [PMID: 31493152 DOI: 10.1007/s00775-019-01709-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/13/2019] [Indexed: 12/12/2022]
Abstract
[FeFe]-hydrogenase catalyzes the reversible reduction of protons to H2 at a complex metallocofactor site, the H-cluster. Biosynthesis of this active-site H-cluster requires three maturation enzymes: the radical S-adenosylmethionine enzymes HydE and HydG synthesize the nonprotein ligands, while the GTPase HydF provides a scaffold for assembly of the 2Fe subcluster of the H-cluster ([2Fe]H) prior to its transfer to hydrogenase. To delineate the assembly and delivery steps for the 2Fe precursor cluster coordinated to HydF ([2Fe]F), we have heterologously expressed HydF in the presence of HydE alone (HydFE) or HydG alone (HydFG), and characterized the resulting purified HydFE and HydFG using UV-visible, EPR, and FTIR spectroscopies and biochemical assays. The iron-sulfur clusters on HydF are modified by co-expression with HydE or HydG, as evidenced by the changes in the visible, EPR, and FTIR spectral features. Further, biochemical assays show that HydFE is capable of activating HydAΔEFG to a limited extent (~ 1% of WT) even though the normal source of CO and CN- ligands of [2Fe]H (HydG) was absent. Activation assays performed with HydFG, in contrast, exhibit no ability to mature HydAΔEFG. It appears that in the case of HydFE, trace diatomics from the cellular environment are incorporated into a [2Fe]F-like precursor on HydF in the absence of HydG. We conclude that the product of HydE, presumably the dithiomethylamine ligand of [2Fe]H, is absolutely essential to the activation process, while the diatomic products of HydG can be provided from alternate sources.
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23
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Bai Y, Chen T, Happe T, Lu Y, Sawyer A. Iron-sulphur cluster biogenesis via the SUF pathway. Metallomics 2019; 10:1038-1052. [PMID: 30019043 DOI: 10.1039/c8mt00150b] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Iron-sulphur (Fe-S) clusters are versatile cofactors, which are essential for key metabolic processes in cells, such as respiration and photosynthesis, and which may have also played a crucial role in establishing life on Earth. They can be found in almost all living organisms, from unicellular prokaryotes and archaea to multicellular animals and plants, and exist in diverse forms. This review focuses on the most ancient Fe-S cluster assembly system, the sulphur utilization factor (SUF) mechanism, which is crucial in bacteria for cell survival under stress conditions such as oxidation and iron starvation, and which is also present in the chloroplasts of green microalgae and plants, where it is responsible for plastidial Fe-S protein maturation. We explain the SUF Fe-S cluster assembly process, the proteins involved, their regulation and provide evolutionary insights. We specifically focus on examples from Fe-S cluster synthesis in the model organisms Escherichia coli and Arabidopsis thaliana and discuss in an in vivo context the assembly of the [FeFe]-hydrogenase H-cluster from Chlamydomonas reinhardtii.
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Affiliation(s)
- Y Bai
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
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24
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Wu Y, Wu R, Mandalapu D, Ji X, Chen T, Ding W, Zhang Q. Radical SAM-dependent adenosylation catalyzed by l-tyrosine lyases. Org Biomol Chem 2019; 17:1809-1812. [DOI: 10.1039/c8ob02906g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tyrosine analogues containing an olefin moiety can be adenosylated by l-tyrosine lyases.
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Affiliation(s)
- Yujie Wu
- State Key Laboratory of Cryospheric Sciences
- Key Laboratory of Extreme Environmental Microbial Resources and Engineering
- Northwest Institute of Eco-environment and Resource
- Chinese Academy of Sciences
- Lanzhou 730000
| | - Runze Wu
- Department of Chemistry
- Fudan University
- Shanghai 200433
- China
| | | | - Xinjian Ji
- Department of Chemistry
- Fudan University
- Shanghai 200433
- China
| | - Tuo Chen
- State Key Laboratory of Cryospheric Sciences
- Key Laboratory of Extreme Environmental Microbial Resources and Engineering
- Northwest Institute of Eco-environment and Resource
- Chinese Academy of Sciences
- Lanzhou 730000
| | - Wei Ding
- Department of Chemistry
- Fudan University
- Shanghai 200433
- China
| | - Qi Zhang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- China
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25
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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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26
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Deng C, Wang Z, Xie Y, He J, Wei J, Zou L, Xie B, Jiang J, Wu Y, Ma Z, Hu M, Li Y, Zhao P, Liu X. Synthesis, Structure, and Electrochemical Properties of O
-Alkyldithiophosphato Nickel Complexes with Chelating Aminodiphosphine Ligands. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Chenglong Deng
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Zheng Wang
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Ying Xie
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Jiao He
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Juan Wei
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Like Zou
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Bin Xie
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Jin Jiang
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Yu Wu
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Zhongyi Ma
- School of Materials Science and Engineering; North University of China; 030051 Taiyuan P. R. China
| | - Mengyuan Hu
- School of Materials Science and Engineering; North University of China; 030051 Taiyuan P. R. China
| | - Yulong Li
- College of Chemistry and Environmental Engineering; Sichuan University of Science & Engineering; 643000 Zigong P. R. China
| | - Peihua Zhao
- School of Materials Science and Engineering; North University of China; 030051 Taiyuan P. R. China
| | - Xufeng Liu
- School of Materials and Chemical Engineering; Ningbo University of Technology; 315211 Ningbo P. R. China
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27
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A [4Fe-4S]-Fe(CO)(CN)-L-cysteine intermediate is the first organometallic precursor in [FeFe] hydrogenase H-cluster bioassembly. Nat Chem 2018; 10:555-560. [PMID: 29632334 PMCID: PMC6380689 DOI: 10.1038/s41557-018-0026-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 02/14/2018] [Indexed: 12/27/2022]
Abstract
Biosynthesis of the [FeFe] hydrogenase active site (the 'H-cluster') requires the interplay of multiple proteins and small molecules. Among them, the radical S-adenosylmethionine enzyme HydG, a tyrosine lyase, has been proposed to generate a complex that contains an Fe(CO)2(CN) moiety that is eventually incorporated into the H-cluster. Here we describe the characterization of an intermediate in the HydG reaction: a [4Fe-4S][(Cys)Fe(CO)(CN)] species, 'Complex A', in which a CO, a CN- and a cysteine (Cys) molecule bind to the unique 'dangler' Fe site of the auxiliary [5Fe-4S] cluster of HydG. The identification of this intermediate-the first organometallic precursor to the H-cluster-validates the previously hypothesized HydG reaction cycle and provides a basis for elucidating the biosynthetic origin of other moieties of the H-cluster.
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Bhandari DM, Fedoseyenko D, Begley TP. Mechanistic Studies on Tryptophan Lyase (NosL): Identification of Cyanide as a Reaction Product. J Am Chem Soc 2018; 140:542-545. [PMID: 29232124 PMCID: PMC6078386 DOI: 10.1021/jacs.7b09000] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tryptophan lyase (NosL) catalyzes the formation of 3-methylindole-2-carboxylic acid and 3-methylindole from l-tryptophan. In this paper, we provide evidence supporting a formate radical intermediate and demonstrate that cyanide is a byproduct of the NosL-catalyzed reaction with l-tryptophan. These experiments require a major revision of the NosL mechanism and uncover an unanticipated connection between NosL and HydG, the radical SAM enzyme that forms cyanide and carbon monoxide from tyrosine during the biosynthesis of the metallo-cluster of the [Fe-Fe] hydrogenase.
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Affiliation(s)
- Dhananjay M. Bhandari
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Dmytro Fedoseyenko
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Tadhg P. Begley
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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29
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Bhandari DM, Fedoseyenko D, Begley TP. Mechanistic Studies on the Radical SAM Enzyme Tryptophan Lyase (NosL). Methods Enzymol 2018; 606:155-178. [DOI: 10.1016/bs.mie.2018.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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30
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Li YL, He J, Wei J, Wei J, Mu C, Wu Y, Xie B, Zou LK, Wang Z, Wu ML, Li HM, Gao F, Zhao PH. Synthesis, structure and electrochemical properties of diiron S-(−)-1-Phenylethylazadithiolate complexes. Polyhedron 2017. [DOI: 10.1016/j.poly.2017.08.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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31
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Qianzhu H, Ji W, Ji X, Chu L, Guo C, Lu W, Ding W, Gao J, Zhang Q. Reactivity of the nitrogen-centered tryptophanyl radical in the catalysis by the radical SAM enzyme NosL. Chem Commun (Camb) 2017; 53:344-347. [PMID: 27929146 DOI: 10.1039/c6cc08869d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The radical SAM tryptophan (Trp) lyase NosL involved in nosiheptide biosynthesis catalyzes two parallel reactions, converting l-Trp to 3-methyl-2-indolic acid (MIA) and to dehydroglycine and 3-methylindole, respectively. The two parallel reactions diverge from a nitrogen-centered tryptophanyl radical intermediate. Here we report an investigation on the intrinsic reactivity of the tryptophanyl radical using a chemical model study and DFT calculations. The kinetics of the formation and fragmentation of this nitrogen-centered radical in NosL catalysis were also studied in detail. Our analysis explains the intriguing catalytic promiscuity of NosL and highlights the remarkable role this enzyme plays in achieving an energetically highly unfavorable transformation.
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Affiliation(s)
- Haocheng Qianzhu
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. and Department of Chemistry, Fudan University, Shanghai, 200433, China.
| | - Wenjuan Ji
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
| | - Xinjian Ji
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
| | - Leixia Chu
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
| | - Chuchu Guo
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
| | - Wei Lu
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
| | - Wei Ding
- Department of Chemistry, Fudan University, Shanghai, 200433, China. and School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Jiangtao Gao
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
| | - Qi Zhang
- Department of Chemistry, Fudan University, Shanghai, 200433, China.
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32
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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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Galazzo L, Maso L, De Rosa E, Bortolus M, Doni D, Acquasaliente L, De Filippis V, Costantini P, Carbonera D. Identifying conformational changes with site-directed spin labeling reveals that the GTPase domain of HydF is a molecular switch. Sci Rep 2017; 7:1714. [PMID: 28490758 PMCID: PMC5431965 DOI: 10.1038/s41598-017-01886-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 04/05/2017] [Indexed: 11/17/2022] Open
Abstract
[FeFe]-hydrogenases catalyse the reduction of protons to hydrogen at a complex 2Fe[4Fe4S] center called H-cluster. The assembly of this active site is a multistep process involving three proteins, HydE, HydF and HydG. According to the current models, HydF has the key double role of scaffold, upon which the final H-cluster precursor is assembled, and carrier to transfer it to the target hydrogenase. The X-ray structure of HydF indicates that the protein is a homodimer with both monomers carrying two functional domains: a C-terminal FeS cluster-binding domain, where the precursor is assembled, and a N-terminal GTPase domain, whose exact contribution to cluster biogenesis and hydrogenase activation is still elusive. We previously obtained several hints suggesting that the binding of GTP to HydF could be involved in the interactions of this scaffold protein with the other maturases and with the hydrogenase itself. In this work, by means of site directed spin labeling coupled to EPR/PELDOR spectroscopy, we explored the conformational changes induced in a recombinant HydF protein by GTP binding, and provide the first clue that the HydF GTPase domain could be involved in the H-cluster assembly working as a molecular switch similarly to other known small GTPases.
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Affiliation(s)
- Laura Galazzo
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131, Padova, Italy
| | - Lorenzo Maso
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy
| | - Edith De Rosa
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131, Padova, Italy
| | - Davide Doni
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131, Padova, Italy
| | - Laura Acquasaliente
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131, Padova, Italy
| | - Vincenzo De Filippis
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131, Padova, Italy
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131, Padova, Italy.
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131, Padova, Italy.
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Morra S, Valetti F, Gilardi G. [FeFe]-hydrogenases as biocatalysts in bio-hydrogen production. RENDICONTI LINCEI 2016. [DOI: 10.1007/s12210-016-0584-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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35
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Dinis P, Wieckowski BM, Roach PL. Metallocofactor assembly for [FeFe]-hydrogenases. Curr Opin Struct Biol 2016; 41:90-97. [PMID: 27344601 DOI: 10.1016/j.sbi.2016.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 06/05/2016] [Accepted: 06/06/2016] [Indexed: 11/27/2022]
Abstract
Hydrogenases are a potential source of environmentally benign bioenergy, using complex cofactors to catalyze the reversible reduction of protons to form hydrogen. The most active subclass, the [FeFe]-hydrogenases, is dependent on a metallocofactor, the H cluster, that consists of a two iron subcluster ([2Fe]H) bridging to a classical cubane cluster ([4Fe-4S]H). The ligands coordinating to the diiron subcluster include an azadithiolate, three carbon monoxides, and two cyanides. To assemble this complex cofactor, three maturase enzymes, HydG, HydE and HydF are required. The biosynthesis of the diatomic ligands proceeds by an unusual fragmentation mechanism, and structural studies in combination with spectroscopic analysis have started to provide insights into the HydG mediated assembly of a [2Fe]H subcluster precursor.
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Affiliation(s)
- Pedro Dinis
- Chemistry and the Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Beata M Wieckowski
- Chemistry and the Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Peter L Roach
- Chemistry and the Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
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36
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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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37
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Suess DLM, Pham CC, Bürstel I, Swartz JR, Cramer SP, Britt RD. The Radical SAM Enzyme HydG Requires Cysteine and a Dangler Iron for Generating an Organometallic Precursor to the [FeFe]-Hydrogenase H-Cluster. J Am Chem Soc 2016; 138:1146-9. [PMID: 26764535 DOI: 10.1021/jacs.5b12512] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Three maturase enzymes-HydE, HydF, and HydG-synthesize and insert the organometallic component of the [FeFe]-hydrogenase active site (the H-cluster). HydG generates the first organometallic intermediates in this process, ultimately producing an [Fe(CO)2(CN)] complex. A limitation in understanding the mechanism by which this complex forms has been uncertainty regarding the precise metallocluster composition of HydG that comprises active enzyme. We herein show that the HydG auxiliary cluster must bind both l-cysteine and a dangler Fe in order to generate the [Fe(CO)2(CN)] product. These findings support a mechanistic framework in which a [(Cys)Fe(CO)2(CN)](-) species is a key intermediate in H-cluster maturation.
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Affiliation(s)
- Daniel L M Suess
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
| | - Cindy C Pham
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
| | | | | | - Stephen P Cramer
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
| | - R David Britt
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
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