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Landwehr V, Milanov M, Angebauer L, Hong J, Jüngert G, Hiersemenzel A, Siebler A, Schmit F, Öztürk Y, Dannenmaier S, Drepper F, Warscheid B, Koch HG. The Universally Conserved ATPase YchF Regulates Translation of Leaderless mRNA in Response to Stress Conditions. Front Mol Biosci 2021; 8:643696. [PMID: 34026826 PMCID: PMC8138138 DOI: 10.3389/fmolb.2021.643696] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 04/13/2021] [Indexed: 12/14/2022] Open
Abstract
The universally conserved P-loop GTPases control diverse cellular processes, like signal transduction, ribosome assembly, cell motility, and intracellular transport and translation. YchF belongs to the Obg-family of P-loop GTPases and is one of the least characterized member of this family. It is unique because it preferentially hydrolyses ATP rather than GTP, but its physiological role is largely unknown. Studies in different organisms including humans suggest a possible role of YchF in regulating the cellular adaptation to stress conditions. In the current study, we explored the role of YchF in the model organism Escherichia coli. By western blot and promoter fusion experiments, we demonstrate that YchF levels decrease during stress conditions or when cells enter stationary phase. The decline in YchF levels trigger increased stress resistance and cells lacking YchF are resistant to multiple stress conditions, like oxidative stress, replication stress, or translational stress. By in vivo site directed cross-linking we demonstrate that YchF interacts with the translation initiation factor 3 (IF3) and with multiple ribosomal proteins at the surface of the small ribosomal subunit. The absence of YchF enhances the anti-association activity of IF3, stimulates the translation of leaderless mRNAs, and increases the resistance against the endoribonuclease MazF, which generates leaderless mRNAs during stress conditions. In summary, our data identify YchF as a stress-responsive regulator of leaderless mRNA translation.
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Affiliation(s)
- Victoria Landwehr
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Martin Milanov
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Larissa Angebauer
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Jiang Hong
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Gabriela Jüngert
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Anna Hiersemenzel
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Ariane Siebler
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Fränk Schmit
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Yavuz Öztürk
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Stefan Dannenmaier
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Friedel Drepper
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Bettina Warscheid
- Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Signalling Research Centers BIOSS and CIBSS, University Freiburg, Freiburg, Germany
| | - Hans-Georg Koch
- Institute for Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Medizin, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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Abstract
Sulfonates include diverse natural products and anthropogenic chemicals and are widespread in the environment. Many bacteria can degrade sulfonates and obtain sulfur, carbon, and energy for growth, playing important roles in the biogeochemical sulfur cycle. Cleavage of the inert sulfonate C-S bond involves a variety of enzymes, cofactors, and oxygen-dependent and oxygen-independent catalytic mechanisms. Sulfonate degradation by strictly anaerobic bacteria was recently found to involve C-S bond cleavage through O2-sensitive free radical chemistry, catalyzed by glycyl radical enzymes (GREs). The associated discoveries of new enzymes and metabolic pathways for sulfonate metabolism in diverse anaerobic bacteria have enriched our understanding of sulfonate chemistry in the anaerobic biosphere. An anaerobic environment of particular interest is the human gut microbiome, where sulfonate degradation by sulfate- and sulfite-reducing bacteria (SSRB) produces H2S, a process linked to certain chronic diseases and conditions.
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Affiliation(s)
- Yifeng Wei
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A*STAR), Singapore 138669
| | - Yan Zhang
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology; and Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China;
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Khademian M, Imlay JA. Do reactive oxygen species or does oxygen itself confer obligate anaerobiosis? The case of Bacteroides thetaiotaomicron. Mol Microbiol 2020; 114:333-347. [PMID: 32301184 DOI: 10.1111/mmi.14516] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/07/2020] [Accepted: 04/07/2020] [Indexed: 02/06/2023]
Abstract
Bacteroides thetaiotaomicron was examined to determine whether its obligate anaerobiosis is imposed by endogenous reactive oxygen species or by molecular oxygen itself. Previous analyses established that aerated B. thetaiotaomicron loses some enzyme activities due to a high rate of endogenous superoxide formation. However, the present study establishes that another key step in central metabolism is poisoned by molecular oxygen itself. Pyruvate dissimilation was shown to depend upon two enzymes, pyruvate:formate lyase (PFL) and pyruvate:ferredoxin oxidoreductase (PFOR), that lose activity upon aeration. PFL is a glycyl-radical enzyme whose vulnerability to oxygen is already understood. The rate of PFOR damage was unaffected by the level of superoxide or peroxide, showing that molecular oxygen itself is the culprit. The cell cannot repair PFOR, which amplifies the impact of damage. The rates of PFOR and fumarase inactivation are similar, suggesting that superoxide dismutase is calibrated so the oxygen- and superoxide-sensitive enzymes are equally sensitive to aeration. The physiological purpose of PFL and PFOR is to degrade pyruvate without disrupting the redox balance, and they do so using catalytic mechanisms that are intrinsically vulnerable to oxygen. In this way, the anaerobic excellence and oxygen sensitivity of B. thetaiotaomicron are two sides of the same coin.
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Affiliation(s)
- Maryam Khademian
- Department of Microbiology, University of Illinois, Urbana, IL, USA
| | - James A Imlay
- Department of Microbiology, University of Illinois, Urbana, IL, USA
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Insights into the metabolism pathway and functional genes of long-chain aliphatic alkane degradation in haloarchaea. Extremophiles 2020; 24:475-483. [DOI: 10.1007/s00792-020-01167-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 03/24/2020] [Indexed: 12/22/2022]
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Imlay JA, Sethu R, Rohaun SK. Evolutionary adaptations that enable enzymes to tolerate oxidative stress. Free Radic Biol Med 2019; 140:4-13. [PMID: 30735836 PMCID: PMC6684875 DOI: 10.1016/j.freeradbiomed.2019.01.048] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 01/31/2019] [Indexed: 10/27/2022]
Abstract
Biochemical mechanisms emerged and were integrated into the metabolic plan of cellular life long before molecular oxygen accumulated in the biosphere. When oxygen levels finaly rose, they threatened specific types of enzymes: those that use organic radicals as catalysts, and those that depend upon iron centers. Nature has found ways to ensure that such enzymes are still used by contemporary organisms. In some cases they are restricted to microbes that reside in anoxic habitats, but in others they manage to function inside aerobic cells. In the latter case, it is frequently true that the ancestral enzyme has been modified to fend off poisoning. In this review we survey a range of protein adaptations that permit radical-based and low-potential iron chemistry to succeed in oxic environments. In many cases, accessory domains shield the vulnerable radical or metal center from oxygen. In others, the structures of iron cofactors evolved to less oxidizable forms, or alternative metals replaced iron altogether. The overarching view is that some classes of biochemical mechanism are intrinsically incompatible with the presence of oxygen. The structural modification of target enzymes is an under-recognized response to this problem.
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Affiliation(s)
- James A Imlay
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA.
| | - Ramakrishnan Sethu
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - Sanjay Kumar Rohaun
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA
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Harrison AO, Moore RM, Polson SW, Wommack KE. Reannotation of the Ribonucleotide Reductase in a Cyanophage Reveals Life History Strategies Within the Virioplankton. Front Microbiol 2019; 10:134. [PMID: 30804913 PMCID: PMC6370689 DOI: 10.3389/fmicb.2019.00134] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 01/21/2019] [Indexed: 01/16/2023] Open
Abstract
Ribonucleotide reductases (RNRs) are ancient enzymes that catalyze the reduction of ribonucleotides to deoxyribonucleotides. They are required for virtually all cellular life and are prominent within viral genomes. RNRs share a common ancestor and must generate a protein radical for direct ribonucleotide reduction. The mechanisms by which RNRs produce radicals are diverse and divide RNRs into three major classes and several subclasses. The diversity of radical generation methods means that cellular organisms and viruses typically contain the RNR best-suited to the environmental conditions surrounding DNA replication. However, such diversity has also fostered high rates of RNR misannotation within subject sequence databases. These misannotations have resulted in incorrect translative presumptions of RNR biochemistry and have diminished the utility of this marker gene for ecological studies of viruses. We discovered a misannotation of the RNR gene within the Prochlorococcus phage P-SSP7 genome, which caused a chain of misannotations within commonly observed RNR genes from marine virioplankton communities. These RNRs are found in marine cyanopodo- and cyanosiphoviruses and are currently misannotated as Class II RNRs, which are O2-independent and require cofactor B12. In fact, these cyanoviral RNRs are Class I enzymes that are O2-dependent and may require a di-metal cofactor made of Fe, Mn, or a combination of the two metals. The discovery of an overlooked Class I β subunit in the P-SSP7 genome, together with phylogenetic analysis of the α and β subunits confirms that the RNR from P-SSP7 is a Class I RNR. Phylogenetic and conserved residue analyses also suggest that the P-SSP7 RNR may constitute a novel Class I subclass. The reannotation of the RNR clade represented by P-SSP7 means that most lytic cyanophage contain Class I RNRs, while their hosts, B12-producing Synechococcus and Prochlorococcus, contain Class II RNRs. By using a Class I RNR, cyanophage avoid a dependence on host-produced B12, a more effective strategy for a lytic virus. The discovery of a novel RNR β subunit within cyanopodoviruses also implies that some unknown viral genes may be familiar cellular genes that are too divergent for homology-based annotation methods to identify.
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Affiliation(s)
- Amelia O. Harrison
- School of Marine Science and Policy, University of Delaware, Newark, DE, United States
| | - Ryan M. Moore
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, United States
| | - Shawn W. Polson
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, United States
| | - K. Eric Wommack
- School of Marine Science and Policy, University of Delaware, Newark, DE, United States
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Mulliez E, Duarte V, Arragain S, Fontecave M, Atta M. On the Role of Additional [4Fe-4S] Clusters with a Free Coordination Site in Radical-SAM Enzymes. Front Chem 2017; 5:17. [PMID: 28361051 PMCID: PMC5352715 DOI: 10.3389/fchem.2017.00017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/03/2017] [Indexed: 11/13/2022] Open
Abstract
The canonical CysXXXCysXXCys motif is the hallmark of the Radical-SAM superfamily. This motif is responsible for the ligation of a [4Fe-4S] cluster containing a free coordination site available for SAM binding. The five enzymes MoaA, TYW1, MiaB, RimO and LipA contain in addition a second [4Fe-4S] cluster itself bound to three other cysteines and thus also displaying a potentially free coordination site. This review article summarizes recent important achievements obtained on these five enzymes with the main focus to delineate the role of this additional [4Fe-4S] cluster in catalysis.
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Affiliation(s)
- Etienne Mulliez
- Biosciences and Biotechnology Institute of Grenoble, Laboratoire de Chimie et Biologie des Métaux, UMR 5249 CEA-Centre National de la Recherche Scientifique-UGA Grenoble, France
| | - Victor Duarte
- Biosciences and Biotechnology Institute of Grenoble, Laboratoire de Chimie et Biologie des Métaux, UMR 5249 CEA-Centre National de la Recherche Scientifique-UGA Grenoble, France
| | - Simon Arragain
- Laboratoire de Chimie des Processus Biologiques, UMR 8229, Collége de France-Centre National de la Recherche Scientifique-Université P. et M. Curie Paris, France
| | - Marc Fontecave
- Biosciences and Biotechnology Institute of Grenoble, Laboratoire de Chimie et Biologie des Métaux, UMR 5249 CEA-Centre National de la Recherche Scientifique-UGAGrenoble, France; Laboratoire de Chimie des Processus Biologiques, UMR 8229, Collége de France-Centre National de la Recherche Scientifique-Université P. et M. CurieParis, France
| | - Mohamed Atta
- Biosciences and Biotechnology Institute of Grenoble, Laboratoire de Chimie et Biologie des Métaux, UMR 5249 CEA-Centre National de la Recherche Scientifique-UGA Grenoble, France
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8
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Crona M, Hofer A, Astorga-Wells J, Sjöberg BM, Tholander F. Biochemical Characterization of the Split Class II Ribonucleotide Reductase from Pseudomonas aeruginosa. PLoS One 2015. [PMID: 26225432 PMCID: PMC4520616 DOI: 10.1371/journal.pone.0134293] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa can grow under both aerobic and anaerobic conditions. Its flexibility with respect to oxygen load is reflected by the fact that its genome encodes all three existing classes of ribonucleotides reductase (RNR): the oxygen-dependent class I RNR, the oxygen-indifferent class II RNR, and the oxygen-sensitive class III RNR. The P. aeruginosa class II RNR is expressed as two separate polypeptides (NrdJa and NrdJb), a unique example of a split RNR enzyme in a free-living organism. A split class II RNR is also found in a few closely related γ-Proteobacteria. We have characterized the P. aeruginosa class II RNR and show that both subunits are required for formation of a biologically functional enzyme that can sustain vitamin B12-dependent growth. Binding of the B12 coenzyme as well as substrate and allosteric effectors resides in the NrdJa subunit, whereas the NrdJb subunit mediates efficient reductive dithiol exchange during catalysis. A combination of activity assays and activity-independent methods like surface plasmon resonance and gas phase electrophoretic macromolecule analysis suggests that the enzymatically active form of the enzyme is a (NrdJa-NrdJb)2 homodimer of heterodimers, and a combination of hydrogen-deuterium exchange experiments and molecular modeling suggests a plausible region in NrdJa that interacts with NrdJb. Our detailed characterization of the split NrdJ from P. aeruginosa provides insight into the biochemical function of a unique enzyme known to have central roles in biofilm formation and anaerobic growth.
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Affiliation(s)
- Mikael Crona
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheeles väg 2, SE-17177, Stockholm, Sweden
| | - Anders Hofer
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187, Umeå, Sweden
| | - Juan Astorga-Wells
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheeles väg 2, SE-17177, Stockholm, Sweden
| | - Britt-Marie Sjöberg
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden
| | - Fredrik Tholander
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheeles väg 2, SE-17177, Stockholm, Sweden
- * E-mail:
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Dragičević I, Barić D, Kovačević B, Golding BT, Smith DM. Non-enzymatic ribonucleotide reduction in the prebiotic context. Chemistry 2015; 21:6132-43. [PMID: 25754795 DOI: 10.1002/chem.201405741] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/02/2015] [Indexed: 12/14/2022]
Abstract
Model studies of prebiotic chemistry have revealed compelling routes for the formation of the building blocks of proteins and RNA, but not DNA. Today, deoxynucleotides required for the construction of DNA are produced by reduction of nucleotides catalysed by ribonucleotide reductases, which are radical enzymes. This study considers potential non-enzymatic routes via intermediate radicals for the ancient formation of deoxynucleotides. In this context, several mechanisms for ribonucleotide reduction, in a putative H2 S/HS(.) environment, are characterized using computational chemistry. A bio-inspired mechanistic cycle involving a keto intermediate and HSSH production is found to be potentially viable. An alternative pathway, proceeding through an enol intermediate is found to exhibit similar energetic requirements. Non-cyclical pathways, in which HSS(.) is generated in the final step instead of HS(.) , show a markedly increased thermodynamic driving force (ca. 70 kJ mol(-1) ) and thus warrant serious consideration in the context of the prebiotic ribonucleotide reduction.
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Affiliation(s)
- Ivan Dragičević
- Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia); Department of Chemistry, Faculty of Science and Education, University of Mostar, Matice hrvatske bb, 88000 Mostar (Bosnia and Herzegovina)
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Shisler KA, Broderick JB. Glycyl radical activating enzymes: structure, mechanism, and substrate interactions. Arch Biochem Biophys 2014; 546:64-71. [PMID: 24486374 PMCID: PMC4083501 DOI: 10.1016/j.abb.2014.01.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 11/20/2022]
Abstract
The glycyl radical enzyme activating enzymes (GRE-AEs) are a group of enzymes that belong to the radical S-adenosylmethionine (SAM) superfamily and utilize a [4Fe-4S] cluster and SAM to catalyze H-atom abstraction from their substrate proteins. GRE-AEs activate homodimeric proteins known as glycyl radical enzymes (GREs) through the production of a glycyl radical. After activation, these GREs catalyze diverse reactions through the production of their own substrate radicals. The GRE-AE pyruvate formate lyase activating enzyme (PFL-AE) is extensively characterized and has provided insights into the active site structure of radical SAM enzymes including GRE-AEs, illustrating the nature of the interactions with their corresponding substrate GREs and external electron donors. This review will highlight research on PFL-AE and will also discuss a few GREs and their respective activating enzymes.
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Affiliation(s)
- Krista A Shisler
- Department of Chemistry & Biochemistry and the Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, MT 59717, United States
| | - Joan B Broderick
- Department of Chemistry & Biochemistry and the Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, MT 59717, United States.
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ZHANG C, LIU G, HUANG M. Ribonucleotide reductase metallocofactor: assembly, maintenance and inhibition. FRONTIERS IN BIOLOGY 2014; 9:104-113. [PMID: 24899886 PMCID: PMC4041730 DOI: 10.1007/s11515-014-1302-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Ribonucleotide reductase (RNR) supplies cellular deoxyribonucleotide triphosphates (dNTP) pools by converting ribonucleotides to the corresponding deoxy forms using radical-based chemistry. Eukaryotic RNR comprises α and β subunits: α contains the catalytic and allosteric sites; β houses a diferric-tyrosyl radical cofactor (FeIII2-Y•) that is required to initiates nucleotide reduction in α. Cells have evolved multi-layered mechanisms to regulate RNR level and activity in order to maintain the adequate sizes and ratios of their dNTP pools to ensure high-fidelity DNA replication and repair. The central role of RNR in nucleotide metabolism also makes it a proven target of chemotherapeutics. In this review, we discuss recent progress in understanding the function and regulation of eukaryotic RNRs, with a focus on studies revealing the cellular machineries involved in RNR metallocofactor biosynthesis and its implication in RNR-targeting therapeutics.
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Affiliation(s)
- Caiguo ZHANG
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Guoqi LIU
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Mingxia HUANG
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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Implications of the inability of Listeria monocytogenes EGD-e to grow anaerobically due to a deletion in the class III NrdD ribonucleotide reductase for its use as a model laboratory strain. J Bacteriol 2011; 193:2931-40. [PMID: 21478338 DOI: 10.1128/jb.01405-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes is a Gram-positive facultative intracellular bacterium that causes life-threatening diseases in humans. It grows and survives in environments of low oxygen tension and under conditions of strict anaerobiosis. Oxygen-limiting conditions may be an important factor in determining its pathogenicity. L. monocytogenes serovar 1/2a strain EGD-e has been employed intensively to elucidate the mechanisms of intracellular multiplication and virulence. Listeria possesses genes encoding class I aerobic and class III anaerobic ribonucleotide reductases (RNRs). The class III RNR consists of a catalytic subunit NrdD and an activase NrdG. Surprisingly, L. monocytogenes EGD-e, but not other L. monocytogenes strains or other listerial species, is unable to grow under strict anaerobic conditions. Inspection of listerial NrdD amino acid sequences revealed a six-amino acid deletion in the C-terminal portion of the EGD-e protein, next to the essential glycyl radical domain. Nevertheless, L. monocytogenes EGD-e can grow under microaerophilic conditions due to the recruitment of residual class Ia RNR activity. A three-dimensional (3D) model based on the structure of bacteriophage T4 NrdD identified the location of the deletion, which appears in a highly conserved part of the NrdD RNR structure, in the α/β barrel domain near the glycyl radical domain. The deleted KITPFE region is essential either for interactions with the NrdG activase or, indirectly, for the stability of the glycyl radical loop. Given that L. monocytogenes EGD-e lacks a functional anaerobic RNR, the present findings are relevant to the interpretation of studies of pathogenesis with this strain specifically, in particular under conditions of low oxygen tension.
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Högbom M. Metal use in ribonucleotide reductase R2, di-iron, di-manganese and heterodinuclear—an intricate bioinorganic workaround to use different metals for the same reaction. Metallomics 2011; 3:110-20. [DOI: 10.1039/c0mt00095g] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Ribonucleotide reductases: substrate specificity by allostery. Biochem Biophys Res Commun 2010; 396:19-23. [PMID: 20494104 DOI: 10.1016/j.bbrc.2010.02.108] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 02/13/2010] [Indexed: 11/24/2022]
Abstract
Ribonucleotide reductases catalyze in all living organisms the production of deoxynucleotides from ribonucleotides. A single enzyme provides a balanced supply of the four dNTPs required for DNA replication. Three different but related classes of enzymes are known. Each class catalyzes the same chemistry using a common radical mechanism involving a thiyl radical of the enzyme but the three classes employ different mechanisms for the generation of the radical. For each class a common allosteric mechanism with ATP and dNTPs as effectors directs the substrate specificity of the enzymes ensuring the appropriate balance of the four dNTPs for DNA replication. Recent crystallographic studies of the catalytic subunits from each class in combination with allosteric effectors, with and without cognate substrates, delineated the structural changes caused by effector binding that direct the specificity of the enzymes towards reduction of the appropriate substrate.
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15
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Luttringer F, Mulliez E, Dublet B, Lemaire D, Fontecave M. The Zn center of the anaerobic ribonucleotide reductase from E. coli. J Biol Inorg Chem 2009; 14:923-33. [DOI: 10.1007/s00775-009-0505-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 04/07/2009] [Indexed: 11/24/2022]
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16
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The role of the maturase HydG in [FeFe]‐hydrogenase active site synthesis and assembly. FEBS Lett 2009; 583:506-11. [DOI: 10.1016/j.febslet.2009.01.004] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 01/07/2009] [Accepted: 01/08/2009] [Indexed: 11/19/2022]
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Grochowski LL, White RH. Promiscuous anaerobes: new and unconventional metabolism in methanogenic archaea. Ann N Y Acad Sci 2007; 1125:190-214. [PMID: 18096851 DOI: 10.1196/annals.1419.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The development of an oxygenated atmosphere on earth resulted in the polarization of life into two major groups, those that could live in the presence of oxygen and those that could not-the aerobes and the anaerobes. The evolution of aerobes from the earliest anaerobic prokaryotes resulted in a variety of metabolic adaptations. Many of these adaptations center on the need to sustain oxygen-sensitive reactions and cofactors to function in the new oxygen-containing atmosphere. Still other metabolic pathways that were not sensitive to oxygen also diverged. This is likely due to the physical separation of the organisms, based on their ability to live in the presence of oxygen, which allowed for the independent evolution of the pathways. Through the study of metabolic pathways in anaerobes and comparison to the more established pathways from aerobes, insight into metabolic evolution can be gained. This, in turn, can allow for extra- polation to those metabolic pathways occurring in the Last Universal Common Ancestor (LUCA). Some of the unique and uncanonical metabolic pathways that have been identified in the archaea with emphasis on the biochemistry of an obligate anaerobic methanogen, Methanocaldococcus jannaschii are reviewed.
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Affiliation(s)
- Laura L Grochowski
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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18
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Seyedsayamdost MR, Xie J, Chan CTY, Schultz PG, Stubbe J. Site-Specific Insertion of 3-Aminotyrosine into Subunit α2 of E. coli Ribonucleotide Reductase: Direct Evidence for Involvement of Y730 and Y731 in Radical Propagation. J Am Chem Soc 2007; 129:15060-71. [DOI: 10.1021/ja076043y] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mohammad R. Seyedsayamdost
- Contribution from the Department of Chemistry and Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, and Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Jianming Xie
- Contribution from the Department of Chemistry and Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, and Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Clement T. Y. Chan
- Contribution from the Department of Chemistry and Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, and Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Peter G. Schultz
- Contribution from the Department of Chemistry and Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, and Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - JoAnne Stubbe
- Contribution from the Department of Chemistry and Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, and Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
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19
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Voevodskaya N, Galander M, Högbom M, Stenmark P, McClarty G, Gräslund A, Lendzian F. Structure of the high-valent FeIIIFeIV state in ribonucleotide reductase (RNR) of Chlamydia trachomatis--combined EPR, 57Fe-, 1H-ENDOR and X-ray studies. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:1254-63. [PMID: 17827077 DOI: 10.1016/j.bbapap.2007.07.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Revised: 06/25/2007] [Accepted: 07/02/2007] [Indexed: 10/23/2022]
Abstract
A recently discovered subgroup of class I ribonucleotide reductase (RNR) found in the infectious bacterium Chlamydia trachomatis (C. trachomatis) was shown to exhibit a high-valent Fe(III)Fe(IV) center instead of the tyrosyl radical observed normally in all class I RNRs. The X-ray structure showed that C. trachomatis WT RNR has a phenylalanine at the position of the active tyrosine in Escherichia coli RNR. In this paper the X-ray structure of variant F127Y is presented, where the tyrosine is restored. Using (1)H- and (57)Fe-ENDOR spectroscopy it is shown, that in WT and variants F127Y and Y129F of C. trachomatis RNR, the Fe(III)Fe(IV) center is virtually identical with the short-lived intermediate X observed during the iron oxygen reconstitution reaction in class I RNR from E. coli. The experimental data are consistent with a recent theoretical model for X, proposing two bridging oxo ligands and one terminal water ligand. A surprising extension of the lifetime of the Fe(III)Fe(IV) state in C. trachomatis from a few seconds to several hours at room temperature was observed under catalytic conditions in the presence of substrate. These findings suggest a possible new role for the Fe(III)Fe(IV) state also in other class I RNR, during the catalytic radical transfer reaction, by which the substrate turnover is started.
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Affiliation(s)
- Nina Voevodskaya
- Department of Biochemistry and Biophysics, Stockholm University, S-10691 Stockholm, Sweden
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20
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Jiang W, Yun D, Saleh L, Barr EW, Xing G, Hoffart LM, Maslak MA, Krebs C, Bollinger JM. A manganese(IV)/iron(III) cofactor in Chlamydia trachomatis ribonucleotide reductase. Science 2007; 316:1188-91. [PMID: 17525338 DOI: 10.1126/science.1141179] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In a conventional class I ribonucleotide reductase (RNR), a diiron(II/II) cofactor in the R2 subunit reacts with oxygen to produce a diiron(III/IV) intermediate, which generates a stable tyrosyl radical (Y*). The Y* reversibly oxidizes a cysteine residue in the R1 subunit to a cysteinyl radical (C*), which abstracts the 3'-hydrogen of the substrate to initiate its reduction. The RNR from Chlamydia trachomatis lacks the Y*, and it had been proposed that the diiron(III/IV) complex in R2 directly generates the C* in R1. By enzyme activity measurements and spectroscopic methods, we show that this RNR actually uses a previously unknown stable manganese(IV)/iron(III) cofactor for radical initiation.
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Affiliation(s)
- Wei Jiang
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
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21
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Using gene expression data and network topology to detect substantial pathways, clusters and switches during oxygen deprivation of Escherichia coli. BMC Bioinformatics 2007; 8:149. [PMID: 17488495 PMCID: PMC1884177 DOI: 10.1186/1471-2105-8-149] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Accepted: 05/08/2007] [Indexed: 11/26/2022] Open
Abstract
Background Biochemical investigations over the last decades have elucidated an increasingly complete image of the cellular metabolism. To derive a systems view for the regulation of the metabolism when cells adapt to environmental changes, whole genome gene expression profiles can be analysed. Moreover, utilising a network topology based on gene relationships may facilitate interpreting this vast amount of information, and extracting significant patterns within the networks. Results Interpreting expression levels as pixels with grey value intensities and network topology as relationships between pixels, allows for an image-like representation of cellular metabolism. While the topology of a regular image is a lattice grid, biological networks demonstrate scale-free architecture and thus advanced image processing methods such as wavelet transforms cannot directly be applied. In the study reported here, one-dimensional enzyme-enzyme pairs were tracked to reveal sub-graphs of a biological interaction network which showed significant adaptations to a changing environment. As a case study, the response of the hetero-fermentative bacterium E. coli to oxygen deprivation was investigated. With our novel method, we detected, as expected, an up-regulation in the pathways of hexose nutrients up-take and metabolism and formate fermentation. Furthermore, our approach revealed a down-regulation in iron processing as well as the up-regulation of the histidine biosynthesis pathway. The latter may reflect an adaptive response of E. coli against an increasingly acidic environment due to the excretion of acidic products during anaerobic growth in a batch culture. Conclusion Based on microarray expression profiling data of prokaryotic cells exposed to fundamental treatment changes, our novel technique proved to extract system changes for a rather broad spectrum of the biochemical network.
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22
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Abstract
This review describes enzymes that contain radicals and/or catalyze reactions with radical intermediates. Because radicals irreversibly react with dioxygen, most of these enzymes occur in anaerobic bacteria and archaea. Exceptions are the families of coenzyme B(12)- and S-adenosylmethionine (SAM)-dependent radical enzymes, of which some members also occur in aerobes. Especially oxygen-sensitive radical enzymes are the glycyl radical enzymes and 2-hydroxyacyl-CoA dehydratases. The latter are activated by an ATP-dependent one-electron transfer and act via a ketyl radical anion mechanism. Related enzymes are the ATP-dependent benzoyl-CoA reductase and the ATP-independent 4-hydroxybenzoyl-CoA reductase. Ketyl radical anions may also be generated by one-electron oxidation as shown by the flavin-adenine-dinucleotide (FAD)- and [4Fe-4S]-containing 4-hydroxybutyryl-CoA dehydratase. Finally, two radical enzymes are discussed, pyruvate:ferredoxin oxidoreductase and methane-forming methyl-CoM reductase, which catalyze their main reaction in two-electron steps, but subsequent electron transfers proceed via radicals.
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Affiliation(s)
- Wolfgang Buckel
- Fachbereich Biologie, Philipps-Universität, D-35032 Marburg, Germany.
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23
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Galander M, Uppsten M, Uhlin U, Lendzian F. Orientation of the Tyrosyl Radical in Salmonella typhimurium Class Ib Ribonucleotide Reductase Determined by High Field EPR of R2F Single Crystals. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84089-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Affiliation(s)
- Perry A Frey
- Department of Biochemistry, University of Wisconsin-Madison, 1710 University Avenue, Madison, Wisconsin 53726, USA
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25
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Galander M, Uppsten M, Uhlin U, Lendzian F. Orientation of the tyrosyl radical in Salmonella typhimurium class Ib ribonucleotide reductase determined by high field EPR of R2F single crystals. J Biol Chem 2006; 281:31743-52. [PMID: 16854982 DOI: 10.1074/jbc.m605089200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The R2 protein of class I ribonucleotide reductase (RNR) generates and stores a tyrosyl radical, located next to a diferric iron center, which is essential for ribonucleotide reduction and thus DNA synthesis. X-ray structures of class Ia and Ib proteins from various organisms served as bases for detailed mechanistic suggestions. The active site tyrosine in R2F of class Ib RNR of Salmonella typhimurium is located at larger distance to the diiron site, and shows a different side chain orientation, as compared with the tyrosine in R2 of class Ia RNR from Escherichia coli. No structural information has been available for the active tyrosyl radical in R2F. Here we report on high field EPR experiments of single crystals of R2F from S. typhimurium, containing the radical Tyr-105*. Full rotational pattern of the spectra were recorded, and the orientation of the g-tensor axes were determined, which directly reflect the orientation of the radical Tyr-105* in the crystal frame. Comparison with the orientation of the reduced tyrosine Tyr-105-OH from the x-ray structure reveals a rotation of the tyrosyl side chain, which reduces the distance between the tyrosyl radical and the nearest iron ligands toward similar values as observed earlier for Tyr-122* in E. coli R2. Presence of the substrate binding subunit R1E did not change the EPR spectra of Tyr-105*, indicating that binding of R2E alone induces no structural change of the diiron site. The present study demonstrates that structural and functional information about active radical states can be obtained by combining x-ray and high-field-EPR crystallography.
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Affiliation(s)
- Marcus Galander
- Max-Volmer Laboratory for Biophysical Chemistry, Technical University Berlin, D-10623 Berlin, Germany
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26
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Abstract
Ribonucleotide reductases (RNRs) transform RNA building blocks to DNA building blocks by catalyzing the substitution of the 2'OH-group of a ribonucleotide with a hydrogen by a mechanism involving protein radicals. Three classes of RNRs employ different mechanisms for the generation of the protein radical. Recent structural studies of members from each class have led to a deeper understanding of their catalytic mechanism and allosteric regulation by nucleoside triphosphates. The main emphasis of this review is on regulation of RNR at the molecular and cellular level. Conformational transitions induced by nucleotide binding determine the regulation of substrate specificity. An intricate interplay between gene activation, enzyme inhibition, and protein degradation regulates, together with the allosteric effects, enzyme activity and provides the appropriate amount of deoxynucleotides for DNA replication and repair. In spite of large differences in the amino acid sequences, basic structural features are remarkably similar and suggest a common evolutionary origin for the three classes.
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Affiliation(s)
- Pär Nordlund
- Division of Biophysics and 2Division of Biochemistry, Medical Nobel Institute, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden.
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27
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Gambarelli S, Luttringer F, Padovani D, Mulliez E, Fontecave M. Activation of the anaerobic ribonucleotide reductase by S-adenosylmethionine. Chembiochem 2006; 6:1960-2. [PMID: 16178037 DOI: 10.1002/cbic.200500182] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Serge Gambarelli
- Service de Chimie Inorganique et Biologique, DRFMC-SCIB, CEA-Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex 9, France
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28
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Bennati M, Lendzian F, Schmittel M, Zipse H. Spectroscopic and theoretical approaches for studying radical reactions in class I ribonucleotide reductase. Biol Chem 2005; 386:1007-22. [PMID: 16218873 DOI: 10.1515/bc.2005.117] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Ribonucleotide reductases (RNRs) catalyze the production of deoxyribonucleotides, which are essential for DNA synthesis and repair in all organisms. The three currently known classes of RNRs are postulated to utilize a similar mechanism for ribonucleotide reduction via a transient thiyl radical, but they differ in the way this radical is generated. Class I RNR, found in all eukaryotic organisms and in some eubacteria and viruses, employs a diferric iron center and a stable tyrosyl radical in a second protein subunit, R2, to drive thiyl radical generation near the substrate binding site in subunit R1. From extensive experimental and theoretical research during the last decades, a general mechanistic model for class I RNR has emerged, showing three major mechanistic steps: generation of the tyrosyl radical by the diiron center in subunit R2, radical transfer to generate the proposed thiyl radical near the substrate bound in subunit R1, and finally catalytic reduction of the bound ribonucleotide. Amino acid- or substrate-derived radicals are involved in all three major reactions. This article summarizes the present mechanistic picture of class I RNR and highlights experimental and theoretical approaches that have contributed to our current understanding of this important class of radical enzymes.
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Affiliation(s)
- Marina Bennati
- Institut für Physikalische und Theoretische Chemie und BMRZ, J.W. Goethe-Universität Frankfurt, Marie-Curie-Str. 11, D-60439 Frankfurt am Main, Germany
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29
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Brazzolotto X, Rubach JK, Gaillard J, Gambarelli S, Atta M, Fontecave M. The [Fe-Fe]-hydrogenase maturation protein HydF from Thermotoga maritima is a GTPase with an iron-sulfur cluster. J Biol Chem 2005; 281:769-74. [PMID: 16278209 DOI: 10.1074/jbc.m510310200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The active site of [Fe-Fe]-hydrogenases is composed of a di-iron complex, where the two metal atoms are bridged together by a putative di(thiomethyl)amine molecule and are also ligated by di-nuclear ligands, namely carbon monoxide and cyanide. Biosynthesis of this metal site is thought to require specific protein machinery coded by the hydE, hydF, and hydG genes. The HydF protein has been cloned from the thermophilic organism Thermotoga maritima, purified, and characterized. The enzyme possesses specific amino acid signatures for GTP binding and is able to hydrolyze GTP. The anaerobically reconstituted TmHydF protein binds a [4Fe-4S] cluster with peculiar EPR characteristics: an S = 1/2 signal presenting a high field shifted g-value together with a S = 3/2 signal, similar to those observed for [4Fe-4S] clusters ligated by only three cysteines. HYSCORE spectroscopy experiments were carried out to determine the nature of the fourth ligand of the cluster, and its exchangeability was demonstrated with the formation of a [4Fe-4S]-imidazole complex.
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Affiliation(s)
- Xavier Brazzolotto
- Laboratoire de Chimie et Biochimie des Centres Rédox Biologiques, UMR Université Joseph Fourier/CNRS/Commissariat à l'Energie Atomique-No. 5047, Grenoble, France
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30
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Lendzian F. Structure and interactions of amino acid radicals in class I ribonucleotide reductase studied by ENDOR and high-field EPR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1707:67-90. [PMID: 15721607 DOI: 10.1016/j.bbabio.2004.02.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Accepted: 02/17/2004] [Indexed: 11/18/2022]
Abstract
This short review compiles high-field electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) studies on different intermediate amino acid radicals, which emerge in wild-type and mutant class I ribonucleotide reductase (RNR) both in the reaction of protein subunit R2 with molecular oxygen, which generates the essential tyrosyl radical, and in the catalytic reaction, which involves a radical transfer between subunits R2 and R1. Recent examples are presented, how different amino acid radicals (tyrosyl, tryptophan, and different cysteine-based radicals) were identified, assigned to a specific residue, and their interactions, in particular hydrogen bonding, were investigated using high-field EPR and ENDOR spectroscopy. Thereby, unexpected diiron-radical centers, which emerge in mutants of R2 with changed iron coordination, and an important catalytic cysteine-based intermediate in the substrate turnover reaction in R1 were identified and characterized. Experiments on the essential tyrosyl radical in R2 single crystals revealed the so far unknown conformational changes induced by formation of the radical. Interesting structural differences between the tyrosyl radicals of class Ia and Ib enzymes were revealed. Recently accurate distances between the tyrosyl radicals in the protein dimer R2 could be determined using pulsed electron-electron double resonance (PELDOR), providing a new tool for docking studies of protein subunits. These studies show that high-field EPR and ENDOR are important tools for the identification and investigation of radical intermediates, which contributed significantly to the current understanding of the reaction mechanism of class I RNR.
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Affiliation(s)
- Friedhelm Lendzian
- Max-Volmer-Laboratory for Biophysical Chemistry, Institute for Chemistry, PC 14, Technical University Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
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31
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Pierrel F, Douki T, Fontecave M, Atta M. MiaB Protein Is a Bifunctional Radical-S-Adenosylmethionine Enzyme Involved in Thiolation and Methylation of tRNA. J Biol Chem 2004; 279:47555-63. [PMID: 15339930 DOI: 10.1074/jbc.m408562200] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The last biosynthetic step for 2-methylthio-N(6)-isopentenyl-adenosine (ms(2)i(6)A), present at position 37 in some tRNAs, consists of the methylthiolation of the isopentenyl-adenosine (i(6)A) precursor. In this work we have reconstituted in vitro the conversion of i(6)A to ms(2)i(6)A within a tRNA substrate using the iron-sulfur MiaB protein, S-adenosylmethionine (AdoMet), and a reducing agent. We show that a synthetic i(6)A-containing RNA corresponding to the anticodon stem loop of tRNA(Phe) is also a substrate. This study demonstrates that MiaB protein is a bifunctional system, involved in both thiolation and methylation of i(6)A. In this process, one molecule of AdoMet is converted to 5'-deoxyadenosine, probably through reductive cleavage and intermediate formation ofa5'-deoxyadenosyl radical as observed in other "Radical-AdoMet" enzymes, and a second molecule of AdoMet is used as a methyl donor as shown by labeling experiments. The origin of the sulfur atom is discussed.
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Affiliation(s)
- Fabien Pierrel
- Laboratoire de Chimie et Biochimie des Centres Rédox Biologiques, DRDC-CB, Unité Mixte de Recherche 5047 Commissariat à l'Energie Atomique/CNRS/Université Joseph Fourier, Grenoble, France
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Larsson KM, Jordan A, Eliasson R, Reichard P, Logan DT, Nordlund P. Structural mechanism of allosteric substrate specificity regulation in a ribonucleotide reductase. Nat Struct Mol Biol 2004; 11:1142-9. [PMID: 15475969 DOI: 10.1038/nsmb838] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Accepted: 08/13/2004] [Indexed: 11/08/2022]
Abstract
Ribonucleotide reductases (RNRs) catalyze the reduction of ribonucleotides into deoxyribonucleotides, which constitute the precursor pools used for DNA synthesis and repair. Imbalances in these pools increase mutational rates and are detrimental to the cell. Balanced precursor pools are maintained primarily through the regulation of the RNR substrate specificity. Here, the molecular mechanism of the allosteric substrate specificity regulation is revealed through the structures of a dimeric coenzyme B12-dependent RNR from Thermotoga maritima, both in complexes with four effector-substrate nucleotide pairs and in three complexes with only effector. The mechanism is based on the flexibility of loop 2, a key structural element, which forms a bridge between the specificity effector and substrate nucleotides. Substrate specificity is achieved as different effectors and their cognate substrates stabilize specific discrete loop 2 conformations. The mechanism of substrate specificity regulation is probably general for most class I and class II RNRs.
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Affiliation(s)
- Karl-Magnus Larsson
- Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden
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33
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Nicolet Y, Drennan CL. AdoMet radical proteins--from structure to evolution--alignment of divergent protein sequences reveals strong secondary structure element conservation. Nucleic Acids Res 2004; 32:4015-25. [PMID: 15289575 PMCID: PMC506812 DOI: 10.1093/nar/gkh728] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Eighteen subclasses of S-adenosyl-l-methionine (AdoMet) radical proteins have been aligned in the first bioinformatics study of the AdoMet radical superfamily to utilize crystallographic information. The recently resolved X-ray structure of biotin synthase (BioB) was used to guide the multiple sequence alignment, and the recently resolved X-ray structure of coproporphyrinogen III oxidase (HemN) was used as the control. Despite the low 9% sequence identity between BioB and HemN, the multiple sequence alignment correctly predicted all but one of the core helices in HemN, and correctly predicted the residues in the enzyme active site. This alignment further suggests that the AdoMet radical proteins may have evolved from half-barrel structures (alphabeta)4 to three-quarter-barrel structures (alphabeta)6 to full-barrel structures (alphabeta)8. It predicts that anaerobic ribonucleotide reductase (RNR) activase, an ancient enzyme that, it has been suggested, serves as a link between the RNA and DNA worlds, will have a half-barrel structure, whereas the three-quarter barrel, exemplified by HemN, will be the most common architecture for AdoMet radical enzymes, and fewer members of the superfamily will join BioB in using a complete (alphabeta)8 TIM-barrel fold to perform radical chemistry. These differences in barrel architecture also explain how AdoMet radical enzymes can act on substrates that range in size from 10 atoms to 608 residue proteins.
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Affiliation(s)
- Yvain Nicolet
- Department of Chemistry 16-573, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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34
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Stubbe J, Nocera DG, Yee CS, Chang MCY. Radical initiation in the class I ribonucleotide reductase: long-range proton-coupled electron transfer? Chem Rev 2003; 103:2167-201. [PMID: 12797828 DOI: 10.1021/cr020421u] [Citation(s) in RCA: 666] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- JoAnne Stubbe
- Department of Chemistry, 77 Massachusetts Avenue, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
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35
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Logan DT, Mulliez E, Larsson KM, Bodevin S, Atta M, Garnaud PE, Sjoberg BM, Fontecave M. A metal-binding site in the catalytic subunit of anaerobic ribonucleotide reductase. Proc Natl Acad Sci U S A 2003; 100:3826-31. [PMID: 12655046 PMCID: PMC153006 DOI: 10.1073/pnas.0736456100] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2002] [Indexed: 11/18/2022] Open
Abstract
A Zn(Cys)(4) center has been found in the C-terminal region of the crystal structure of the anaerobic class III ribonucleotide reductase (RNR) from bacteriophage T4. The metal center is structurally related to the zinc ribbon motif and to rubredoxin and rubrerythrin. Mutant enzymes of the homologous RNR from Escherichia coli, in which the coordinating cysteines, conserved in almost all known class III RNR sequences, have been mutated into alanines, are shown to be inactive as the result of their inability to generate the catalytically essential glycyl radical. The possible roles of the metal center are discussed in relationship to the currently proposed reaction mechanism for generation of the glycyl radical in class III RNRs.
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Affiliation(s)
- Derek T Logan
- Department of Molecular Biophysics, Lund University, Box 124, 221 00 Lund, Sweden.
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