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Eren E, Watts NR, Conway JF, Wingfield PT. Myxococcus xanthus encapsulin cargo protein EncD is a flavin-binding protein with ferric reductase activity. Proc Natl Acad Sci U S A 2024; 121:e2400426121. [PMID: 38748579 PMCID: PMC11126975 DOI: 10.1073/pnas.2400426121] [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: 01/08/2024] [Accepted: 04/18/2024] [Indexed: 05/27/2024] Open
Abstract
Encapsulins are protein nanocompartments that regulate cellular metabolism in several bacteria and archaea. Myxococcus xanthus encapsulins protect the bacterial cells against oxidative stress by sequestering cytosolic iron. These encapsulins are formed by the shell protein EncA and three cargo proteins: EncB, EncC, and EncD. EncB and EncC form rotationally symmetric decamers with ferroxidase centers (FOCs) that oxidize Fe+2 to Fe+3 for iron storage in mineral form. However, the structure and function of the third cargo protein, EncD, have yet to be determined. Here, we report the x-ray crystal structure of EncD in complex with flavin mononucleotide. EncD forms an α-helical hairpin arranged as an antiparallel dimer, but unlike other flavin-binding proteins, it has no β-sheet, showing that EncD and its homologs represent a unique class of bacterial flavin-binding proteins. The cryo-EM structure of EncA-EncD encapsulins confirms that EncD binds to the interior of the EncA shell via its C-terminal targeting peptide. With only 100 amino acids, the EncD α-helical dimer forms the smallest flavin-binding domain observed to date. Unlike EncB and EncC, EncD lacks a FOC, and our biochemical results show that EncD instead is a NAD(P)H-dependent ferric reductase, indicating that the M. xanthus encapsulins act as an integrated system for iron homeostasis. Overall, this work contributes to our understanding of bacterial metabolism and could lead to the development of technologies for iron biomineralization and the production of iron-containing materials for the treatment of various diseases associated with oxidative stress.
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Affiliation(s)
- Elif Eren
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
| | - Norman R. Watts
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
| | - James F. Conway
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA15260
| | - Paul T. Wingfield
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
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2
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Rivera M. Mobilization of iron stored in bacterioferritin, a new target for perturbing iron homeostasis and developing antibacterial and antibiofilm molecules. J Inorg Biochem 2023; 247:112306. [PMID: 37451083 DOI: 10.1016/j.jinorgbio.2023.112306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/08/2023] [Accepted: 06/24/2023] [Indexed: 07/18/2023]
Abstract
Antibiotic resistance is a global public health threat. The care of chronic infections is complicated by bacterial biofilms. Biofilm embedded cells can be up to 1000-fold more tolerant to antibiotic treatment than planktonic cells. Antibiotic tolerance is a condition which does not involve mutation and enables bacteria to survive in the presence of antibiotics. The antibiotic tolerance of biofilm-cells often renders antibiotics ineffective, even against strains that do not carry resistance-impairing mutations. This review discusses bacterial iron homeostasis and the strategies being developed to target this bacterial vulnerability, with emphasis on a recently proposed approach which aims at targeting the iron storage protein bacterioferritin (Bfr) and its physiological partner, the ferredoxin Bfd. Bfr regulates cytosolic iron concentrations by oxidizing Fe2+ and storing Fe3+ in its internal cavity, and by forming a complex with Bfd to reduce Fe3+ in the internal cavity and release Fe2+ to the cytosol. Blocking the Bfr-Bfd complex in P. aeruginosa cells causes an irreversible accumulation of Fe3+ in BfrB and simultaneous cytosolic iron depletion, which leads to impaired biofilm maintenance and biofilm cell death. Recently discovered small molecule inhibitors of the Bfr-Bfd complex, which bind Bfr at the Bfd binding site, inhibit iron mobilization, and elicit biofilm cell death.
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Affiliation(s)
- Mario Rivera
- Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, LA 70803, USA.
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3
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Zhou X, Liu F, Li N, Zhang Y. Large-Scale Qualitative and Quantitative Assessment of Dityrosine Crosslinking Omics in Response to Endogenous and Exogenous Hydrogen Peroxide in Escherichia coli. Antioxidants (Basel) 2023; 12:antiox12040786. [PMID: 37107161 PMCID: PMC10135038 DOI: 10.3390/antiox12040786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/29/2023] Open
Abstract
Excessive hydrogen peroxide causes oxidative stress in cells. The oxidation of two tyrosine residues in proteins can generate o,o'-dityrosine, a putative biomarker for protein oxidation, which plays critical roles in a variety of organisms. Thus far, few studies have investigated dityrosine crosslinking under endogenous or exogenous oxidative conditions at the proteome level, and its physiological function remains largely unknown. In this study, to investigate qualitative and quantitative dityrosine crosslinking, two mutant Escherichia coli strains and one mutant strain supplemented with H2O2 were used as models for endogenous and exogenous oxidative stress, respectively. By integrating high-resolution liquid chromatography-mass spectrometry and bioinformatic analysis, we created the largest dityrosine crosslinking dataset in E. coli to date, identifying 71 dityrosine crosslinks and 410 dityrosine loop links on 352 proteins. The dityrosine-linked proteins are mainly involved in taurine and hypotaurine metabolism, citrate cycle, glyoxylate, dicarboxylate metabolism, carbon metabolism, etc., suggesting that dityrosine crosslinking may play a critical role in regulating the metabolic pathways in response to oxidative stress. In conclusion, we have reported the most comprehensive dityrosine crosslinking in E. coli for the first time, which is of great significance in revealing its function in oxidative stress.
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Affiliation(s)
- Xiangzhe Zhou
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Feng Liu
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
- Institute of Engineering Medicine, School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Nuomin Li
- Institute of Engineering Medicine, School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Yongqian Zhang
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
- Institute of Engineering Medicine, School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China
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4
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Gehrer CM, Mitterstiller AM, Grubwieser P, Meyron-Holtz EG, Weiss G, Nairz M. Advances in Ferritin Physiology and Possible Implications in Bacterial Infection. Int J Mol Sci 2023; 24:4659. [PMID: 36902088 PMCID: PMC10003477 DOI: 10.3390/ijms24054659] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/17/2023] [Accepted: 02/25/2023] [Indexed: 03/04/2023] Open
Abstract
Due to its advantageous redox properties, iron plays an important role in the metabolism of nearly all life. However, these properties are not only a boon but also the bane of such life forms. Since labile iron results in the generation of reactive oxygen species by Fenton chemistry, iron is stored in a relatively safe form inside of ferritin. Despite the fact that the iron storage protein ferritin has been extensively researched, many of its physiological functions are hitherto unresolved. However, research regarding ferritin's functions is gaining momentum. For example, recent major discoveries on its secretion and distribution mechanisms have been made as well as the paradigm-changing finding of intracellular compartmentalization of ferritin via interaction with nuclear receptor coactivator 4 (NCOA4). In this review, we discuss established knowledge as well as these new findings and the implications they may have for host-pathogen interaction during bacterial infection.
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Affiliation(s)
- Clemens M. Gehrer
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anna-Maria Mitterstiller
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Philipp Grubwieser
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Esther G. Meyron-Holtz
- Laboratory of Molecular Nutrition, Faculty of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Günter Weiss
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
- Christian Doppler Laboratory for Iron Metabolism and Anemia Research, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Manfred Nairz
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
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5
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Morphological difference of Escherichia coli non-heme ferritin iron cores reconstituted in the presence and absence of inorganic phosphate. J Biol Inorg Chem 2022; 27:583-594. [DOI: 10.1007/s00775-022-01952-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/28/2022] [Indexed: 10/15/2022]
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6
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Abstract
The DNA-binding protein from starved cells, Dps, is a universally conserved prokaryotic ferritin that, in many species, also binds DNA. Dps homologs have been identified in the vast majority of bacterial species and several archaea. Dps also may play a role in the global regulation of gene expression, likely through chromatin reorganization. Dps has been shown to use both its ferritin and DNA-binding functions to respond to a variety of environmental pressures, including oxidative stress. One mechanism that allows Dps to achieve this is through a global nucleoid restructuring event during stationary phase, resulting in a compact, hexacrystalline nucleoprotein complex called the biocrystal that occludes damaging agents from DNA. Due to its small size, hollow spherical structure, and high stability, Dps is being developed for applications in biotechnology.
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Eren E, Wang B, Winkler DC, Watts NR, Steven AC, Wingfield PT. Structural characterization of the Myxococcus xanthus encapsulin and ferritin-like cargo system gives insight into its iron storage mechanism. Structure 2022; 30:551-563.e4. [PMID: 35150605 PMCID: PMC8995368 DOI: 10.1016/j.str.2022.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 11/22/2021] [Accepted: 01/18/2022] [Indexed: 10/19/2022]
Abstract
Encapsulins are bacterial organelle-like cages involved in various aspects of metabolism, especially protection from oxidative stress. They can serve as vehicles for a wide range of medical applications. Encapsulin shell proteins are structurally similar to HK97 bacteriophage capsid protein and their function depends on the encapsulated cargos. The Myxococcus xanthus encapsulin system comprises EncA and three cargos: EncB, EncC, and EncD. EncB and EncC are similar to bacterial ferritins that can oxidize Fe+2 to less toxic Fe+3. We analyzed EncA, EncB, and EncC by cryo-EM and X-ray crystallography. Cryo-EM shows that EncA cages can have T = 3 and T = 1 symmetry and that EncA T = 1 has a unique protomer arrangement. Also, we define EncB and EncC binding sites on EncA. X-ray crystallography of EncB and EncC reveals conformational changes at the ferroxidase center and additional metal binding sites, suggesting a mechanism for Fe oxidation and storage within the encapsulin shell.
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8
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Banerjee R, Srinivas V, Lebrette H. Ferritin-Like Proteins: A Conserved Core for a Myriad of Enzyme Complexes. Subcell Biochem 2022; 99:109-153. [PMID: 36151375 DOI: 10.1007/978-3-031-00793-4_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Ferritin-like proteins share a common fold, a four α-helix bundle core, often coordinating a pair of metal ions. Although conserved, the ferritin fold permits a diverse set of reactions, and is central in a multitude of macromolecular enzyme complexes. Here, we emphasize this diversity through three members of the ferritin-like superfamily: the soluble methane monooxygenase, the class I ribonucleotide reductase and the aldehyde deformylating oxygenase. They all rely on dinuclear metal cofactors to catalyze different challenging oxygen-dependent reactions through the formation of multi-protein complexes. Recent studies using cryo-electron microscopy, serial femtosecond crystallography at an X-ray free electron laser source, or single-crystal X-ray diffraction, have reported the structures of the active protein complexes, and revealed unprecedented insights into the molecular mechanisms of these three enzymes.
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Affiliation(s)
- Rahul Banerjee
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Vivek Srinivas
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, UPS, Université de Toulouse, Toulouse, France.
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9
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Zurita C, Tsushima S, Solari PL, Jeanson A, Creff G, Den Auwer C. Interaction of Th(IV), Pu(IV) and Fe(III) with ferritin protein: how similar? JOURNAL OF SYNCHROTRON RADIATION 2022; 29:45-52. [PMID: 34985422 PMCID: PMC8733997 DOI: 10.1107/s1600577521012340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/21/2021] [Indexed: 05/28/2023]
Abstract
Ferritin is the main protein of Fe storage in eukaryote and prokaryote cells. It is a large multifunctional, multi-subunit protein consisting of heavy H and light L subunits. In the field of nuclear toxicology, it has been suggested that some actinide elements, such as thorium and plutonium at oxidation state +IV, have a comparable `biochemistry' to iron at oxidation state +III owing to their very high tendency for hydrolysis and somewhat comparable ionic radii. Therefore, the possible mechanisms of interaction of such actinide elements with the Fe storage protein is a fundamental question of bio-actinidic chemistry. We recently described the complexation of Pu(IV) and Th(IV) with horse spleen ferritin (composed mainly of L subunits). In this article, we bring another viewpoint to this question by further combining modeling with our previous EXAFS data for Pu(IV) and Th(IV). As a result, the interaction between the L subunits and both actinides appears to be non-specific but driven only by the density of the presence of Asp and Glu residues on the protein shell. The formation of an oxyhydroxide Th or Pu core has not been observed under the experimental conditions here, nor the interaction of Th or Pu with the ferric oxyhydroxide core.
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Affiliation(s)
- Cyril Zurita
- Université Côte d’Azur, CNRS, ICN, 06108 Nice, France
| | - Satoru Tsushima
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany
- World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan
| | | | | | - Gaëlle Creff
- Université Côte d’Azur, CNRS, ICN, 06108 Nice, France
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10
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11
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Bradley JM, Fair J, Hemmings AM, Le Brun NE. Key carboxylate residues for iron transit through the prokaryotic ferritin SynFtn. MICROBIOLOGY (READING, ENGLAND) 2021; 167. [PMID: 34825885 PMCID: PMC8743623 DOI: 10.1099/mic.0.001105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Ferritins are proteins forming 24meric rhombic dodecahedral cages that play a key role in iron storage and detoxification in all cell types. Their function requires the transport of Fe2+ from the exterior of the protein to buried di-iron catalytic sites, known as ferroxidase centres, where Fe2+ is oxidized to form Fe3+-oxo precursors of the ferritin mineral core. The route of iron transit through animal ferritins is well understood: the Fe2+ substrate enters the protein via channels at the threefold axes and conserved carboxylates on the inner surface of the protein cage have been shown to contribute to transient binding sites that guide Fe2+ to the ferroxidase centres. The routes of iron transit through prokaryotic ferritins are less well studied but for some, at least, there is evidence that channels at the twofold axes are the major route for Fe2+ uptake. SynFtn, isolated from the cyanobacterium Synechococcus CC9311, is an atypical prokaryotic ferritin that was recently shown to take up Fe2+ via its threefold channels. However, the transfer site carboxylate residues conserved in animal ferritins are absent, meaning that the route taken from the site of iron entry into SynFtn to the catalytic centre is yet to be defined. Here, we report the use of a combination of site-directed mutagenesis, absorbance-monitored activity assays and protein crystallography to probe the effect of substitution of two residues potentially involved in this pathway. Both Glu141 and Asp65 play a role in guiding the Fe2+ substrate to the ferroxidase centre. In the absence of Asp65, routes for Fe2+ to, and Fe3+ exit from, the ferroxidase centre are affected resulting in inefficient formation of the mineral core. These observations further define the iron transit route in what may be the first characterized example of a new class of ferritins peculiar to cyanobacteria.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Joshua Fair
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.,Centre for Molecular and Structural Biochemistry, School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
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12
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Brown JB, Lee MA, Smith AT. Ins and Outs: Recent Advancements in Membrane Protein-Mediated Prokaryotic Ferrous Iron Transport. Biochemistry 2021; 60:3277-3291. [PMID: 34670078 DOI: 10.1021/acs.biochem.1c00586] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Iron is an essential nutrient for virtually every living organism, especially pathogenic prokaryotes. Despite its importance, however, both the acquisition and the export of this element require dedicated pathways that are dependent on oxidation state. Due to its solubility and kinetic lability, reduced ferrous iron (Fe2+) is useful to bacteria for import, chaperoning, and efflux. Once imported, ferrous iron may be loaded into apo and nascent enzymes and even sequestered into storage proteins under certain conditions. However, excess labile ferrous iron can impart toxicity as it may spuriously catalyze Fenton chemistry, thereby generating reactive oxygen species and leading to cellular damage. In response, it is becoming increasingly evident that bacteria have evolved Fe2+ efflux pumps to deal with conditions of ferrous iron excess and to prevent intracellular oxidative stress. In this work, we highlight recent structural and mechanistic advancements in our understanding of prokaryotic ferrous iron import and export systems, with a focus on the connection of these essential transport systems to pathogenesis. Given the connection of these pathways to the virulence of many increasingly antibiotic resistant bacterial strains, a greater understanding of the mechanistic details of ferrous iron cycling in pathogens could illuminate new pathways for future therapeutic developments.
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Affiliation(s)
- Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Mark A Lee
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
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13
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Caldas Nogueira ML, Pastore AJ, Davidson VL. Diversity of structures and functions of oxo-bridged non-heme diiron proteins. Arch Biochem Biophys 2021; 705:108917. [PMID: 33991497 DOI: 10.1016/j.abb.2021.108917] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023]
Abstract
Oxo-bridged diiron proteins are a distinct class of non-heme iron proteins. Their active sites are composed of two irons that are coordinated by amino acid side chains, and a bridging oxygen that interacts with each iron. These proteins are members of the ferritin superfamily and share the structural feature of a four α-helix bundle that provides the residues that coordinate the irons. The different proteins also display a wide range of structures and functions. A prototype of this family is hemerythrin, which functions as an oxygen transporter. Several other hemerythrin-like proteins have been described with a diversity of functions including oxygen and iron sensing, and catalytic activities. Rubrerythrins react with hydrogen peroxide and rubrerythrin-like proteins possess a rubredoxin domain, in addition to the oxo-bridged diiron center. Other redox enzymes with oxo-bridged irons include flavodiiron proteins that act as O2 or NO reductases, ribonucleotide reductase and methane monooxygenase. Ferritins have an oxo-bridged diiron in the ferroxidase center of the protein, which plays a role in the iron storage function of these proteins. There are also bacterial ferritins that exhibit catalytic activities. The structures and functions of this broad class of oxo-bridged diiron proteins are described and compared in this review.
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Affiliation(s)
- Maria Luiza Caldas Nogueira
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States
| | - Anthony J Pastore
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States.
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14
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Bradley JM, Svistunenko DA, Wilson MT, Hemmings AM, Moore GR, Le Brun NE. Bacterial iron detoxification at the molecular level. J Biol Chem 2021; 295:17602-17623. [PMID: 33454001 PMCID: PMC7762939 DOI: 10.1074/jbc.rev120.007746] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 10/07/2020] [Indexed: 01/18/2023] Open
Abstract
Iron is an essential micronutrient, and, in the case of bacteria, its availability is commonly a growth-limiting factor. However, correct functioning of cells requires that the labile pool of chelatable "free" iron be tightly regulated. Correct metalation of proteins requiring iron as a cofactor demands that such a readily accessible source of iron exist, but overaccumulation results in an oxidative burden that, if unchecked, would lead to cell death. The toxicity of iron stems from its potential to catalyze formation of reactive oxygen species that, in addition to causing damage to biological molecules, can also lead to the formation of reactive nitrogen species. To avoid iron-mediated oxidative stress, bacteria utilize iron-dependent global regulators to sense the iron status of the cell and regulate the expression of proteins involved in the acquisition, storage, and efflux of iron accordingly. Here, we survey the current understanding of the structure and mechanism of the important members of each of these classes of protein. Diversity in the details of iron homeostasis mechanisms reflect the differing nutritional stresses resulting from the wide variety of ecological niches that bacteria inhabit. However, in this review, we seek to highlight the similarities of iron homeostasis between different bacteria, while acknowledging important variations. In this way, we hope to illustrate how bacteria have evolved common approaches to overcome the dual problems of the insolubility and potential toxicity of iron.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
| | | | - Michael T Wilson
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom; Centre for Molecular and Structural Biochemistry, School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
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15
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Piergentili C, Ross J, He D, Gallagher KJ, Stanley WA, Adam L, Mackay CL, Baslé A, Waldron KJ, Clarke DJ, Marles-Wright J. Dissecting the structural and functional roles of a putative metal entry site in encapsulated ferritins. J Biol Chem 2020; 295:15511-15526. [PMID: 32878987 DOI: 10.1074/jbc.ra120.014502] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/24/2020] [Indexed: 11/06/2022] Open
Abstract
Encapsulated ferritins belong to the universally distributed ferritin superfamily, whose members function as iron detoxification and storage systems. Encapsulated ferritins have a distinct annular structure and must associate with an encapsulin nanocage to form a competent iron store that is capable of holding significantly more iron than classical ferritins. The catalytic mechanism of iron oxidation in the ferritin family is still an open question because of the differences in organization of the ferroxidase catalytic site and neighboring secondary metal-binding sites. We have previously identified a putative metal-binding site on the inner surface of the Rhodospirillum rubrum encapsulated ferritin at the interface between the two-helix subunits and proximal to the ferroxidase center. Here we present a comprehensive structural and functional study to investigate the functional relevance of this putative iron-entry site by means of enzymatic assays, MS, and X-ray crystallography. We show that catalysis occurs in the ferroxidase center and suggest a dual role for the secondary site, which both serves to attract metal ions to the ferroxidase center and acts as a flow-restricting valve to limit the activity of the ferroxidase center. Moreover, confinement of encapsulated ferritins within the encapsulin nanocage, although enhancing the ability of the encapsulated ferritin to undergo catalysis, does not influence the function of the secondary site. Our study demonstrates a novel molecular mechanism by which substrate flux to the ferroxidase center is controlled, potentially to ensure that iron oxidation is productively coupled to mineralization.
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Affiliation(s)
- Cecilia Piergentili
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jennifer Ross
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, Scotland
| | - Didi He
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland
| | - Kelly J Gallagher
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, Scotland
| | - Will A Stanley
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Laurène Adam
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - C Logan Mackay
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, Scotland
| | - Arnaud Baslé
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Kevin J Waldron
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David J Clarke
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, Scotland.
| | - Jon Marles-Wright
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
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16
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Demchuk AM, Patel TR. The biomedical and bioengineering potential of protein nanocompartments. Biotechnol Adv 2020; 41:107547. [PMID: 32294494 DOI: 10.1016/j.biotechadv.2020.107547] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 03/21/2020] [Accepted: 04/03/2020] [Indexed: 12/18/2022]
Abstract
Protein nanocompartments (PNCs) are self-assembling biological nanocages that can be harnessed as platforms for a wide range of nanobiotechnology applications. The most widely studied examples of PNCs include virus-like particles, bacterial microcompartments, encapsulin nanocompartments, enzyme-derived nanocages (such as lumazine synthase and the E2 component of the pyruvate dehydrogenase complex), ferritins and ferritin homologues, small heat shock proteins, and vault ribonucleoproteins. Structural PNC shell proteins are stable, biocompatible, and tolerant of both interior and exterior chemical or genetic functionalization for use as vaccines, therapeutic delivery vehicles, medical imaging aids, bioreactors, biological control agents, emulsion stabilizers, or scaffolds for biomimetic materials synthesis. This review provides an overview of the recent biomedical and bioengineering advances achieved with PNCs with a particular focus on recombinant PNC derivatives.
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Affiliation(s)
- Aubrey M Demchuk
- Department of Neuroscience, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, Canada.
| | - Trushar R Patel
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, Canada; Department of Microbiology, Immunology and Infectious Diseases, Cumming, School of Medicine, University of Calgary, 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada; Li Ka Shing Institute of Virology and Discovery Lab, Faculty of Medicine & Dentistry, University of Alberta, 6-010 Katz Center for Health Research, Edmonton, AB T6G 2E1, Canada.
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17
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Effect of the point mutation H54N on the ferroxidase process of Rana catesbeiana H′ ferritin. J Inorg Biochem 2019; 197:110697. [DOI: 10.1016/j.jinorgbio.2019.110697] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/23/2019] [Accepted: 04/24/2019] [Indexed: 01/15/2023]
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18
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Yao Q, Weaver SJ, Mock JY, Jensen GJ. Fusion of DARPin to Aldolase Enables Visualization of Small Protein by Cryo-EM. Structure 2019; 27:1148-1155.e3. [PMID: 31080120 PMCID: PMC6610650 DOI: 10.1016/j.str.2019.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 03/04/2019] [Accepted: 04/05/2019] [Indexed: 12/21/2022]
Abstract
Solving protein structures by single-particle cryoelectron microscopy (cryo-EM) has become a crucial tool in structural biology. While exciting progress is being made toward the visualization of small macromolecules, the median protein size in both eukaryotes and bacteria is still beyond the reach of cryo-EM. To overcome this problem, we implemented a platform strategy in which a small protein target was rigidly attached to a large, symmetric base via a selectable adapter. Of our seven designs, the best construct used a designed ankyrin repeat protein (DARPin) rigidly fused to tetrameric rabbit muscle aldolase through a helical linker. The DARPin retained its ability to bind its target: GFP. We solved the structure of this complex to 3.0 Å resolution overall, with 5-8 Å resolution in the GFP region. As flexibility in the DARPin position limited the overall resolution of the target, we describe strategies to rigidify this element.
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Affiliation(s)
- Qing Yao
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA
| | - Sara J Weaver
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA
| | - Jee-Young Mock
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, 1200 E. California Boulevard, Pasadena, CA 91125, USA.
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19
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Sato D, Ikeguchi M. Mechanisms of ferritin assembly studied by time-resolved small-angle X-ray scattering. Biophys Rev 2019; 11:449-455. [PMID: 31069627 DOI: 10.1007/s12551-019-00538-x] [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: 03/18/2019] [Accepted: 04/26/2019] [Indexed: 10/26/2022] Open
Abstract
The assembly reaction of Escherichia coli ferritin A (EcFtnA) was studied using time-resolved small-angle X-ray scattering (SAXS). EcFtnA forms a cage-like structure that consists of 24 identical subunits and dissociates into dimers at acidic pH. The dimer maintains native-like secondary and tertiary structures and can reassemble into a 24-mer when the pH is increased. The time-dependent changes in the SAXS profiles of ferritin during its assembly were roughly explained by a simple model in which only tetramers, hexamers, and dodecamers were considered intermediates. The rate of assembly increased with increasing ionic strength and decreased with increasing pH (from pH 6 to pH 8). These tendencies might originate from repulsion between assembly units (dimers) with the same net charge sign. To test this hypothesis, ferritin mutants with different net charges (net-charge mutants) were prepared. In buffers with low ionic strength, the rate of assembly increased with decreasing net charge. Thus, repulsion between the assembly unit net charges was an important factor influencing the assembly rate. Although the differences in the assembly rate among net-charge mutants were not significant in buffers with an ionic strength higher than 0.1, the assembly rates increased with increasing ionic strength, suggesting that local electrostatic interactions are also responsible for the ionic-strength dependence of the assembly rate and are, on average, repulsive.
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Affiliation(s)
- Daisuke Sato
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo, 192-8577, Japan
| | - Masamichi Ikeguchi
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo, 192-8577, Japan.
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20
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Attachment of flagellin enhances the immunostimulatory activity of a hemagglutinin-ferritin nano-cage. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2019; 17:223-235. [DOI: 10.1016/j.nano.2019.01.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 10/31/2018] [Accepted: 01/11/2019] [Indexed: 12/15/2022]
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21
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Reaction of O 2 with a diiron protein generates a mixed-valent Fe 2+/Fe 3+ center and peroxide. Proc Natl Acad Sci U S A 2019; 116:2058-2067. [PMID: 30659147 DOI: 10.1073/pnas.1809913116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The gene encoding the cyanobacterial ferritin SynFtn is up-regulated in response to copper stress. Here, we show that, while SynFtn does not interact directly with copper, it is highly unusual in several ways. First, its catalytic diiron ferroxidase center is unlike those of all other characterized prokaryotic ferritins and instead resembles an animal H-chain ferritin center. Second, as demonstrated by kinetic, spectroscopic, and high-resolution X-ray crystallographic data, reaction of O2 with the di-Fe2+ center results in a direct, one-electron oxidation to a mixed-valent Fe2+/Fe3+ form. Iron-O2 chemistry of this type is currently unknown among the growing family of proteins that bind a diiron site within a four α-helical bundle in general and ferritins in particular. The mixed-valent form, which slowly oxidized to the more usual di-Fe3+ form, is an intermediate that is continually generated during mineralization. Peroxide, rather than superoxide, is shown to be the product of O2 reduction, implying that ferroxidase centers function in pairs via long-range electron transfer through the protein resulting in reduction of O2 bound at only one of the centers. We show that electron transfer is mediated by the transient formation of a radical on Tyr40, which lies ∼4 Å from the diiron center. As well as demonstrating an expansion of the iron-O2 chemistry known to occur in nature, these data are also highly relevant to the question of whether all ferritins mineralize iron via a common mechanism, providing unequivocal proof that they do not.
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22
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Hagen WR, Hagedoorn PL, Honarmand Ebrahimi K. The workings of ferritin: a crossroad of opinions. Metallomics 2018; 9:595-605. [PMID: 28573266 DOI: 10.1039/c7mt00124j] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Biochemistry of the essential element iron is complicated by radical chemistry associated with Fe(ii) ions and by the extremely low solubility of the Fe(iii) ion in near-neutral water. To mitigate these problems cells from all domains of life synthesize the protein ferritin to take up and oxidize Fe(ii) and to form a soluble storage of Fe(iii) from which iron can be made available for physiology. A long history of studies on ferritin has not yet resulted in a generally accepted mechanism of action of this enzyme. In fact strong disagreement exists between extant ideas on several key steps in the workings of ferritin. The scope of this review is to explain the experimental background of these controversies and to indicate directions towards their possible resolution.
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Affiliation(s)
- Wilfred R Hagen
- Delft University of Technology, Department of Biotechnology, van der Maasweg 9, 2629 HZ Delft, The Netherlands.
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23
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Ardini M, Howes BD, Fiorillo A, Falvo E, Sottini S, Rovai D, Lantieri M, Ilari A, Gatteschi D, Spina G, Chiancone E, Stefanini S, Fittipaldi M. Study of manganese binding to the ferroxidase centre of human H-type ferritin. J Inorg Biochem 2018; 182:103-112. [PMID: 29454149 DOI: 10.1016/j.jinorgbio.2018.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/11/2018] [Accepted: 02/04/2018] [Indexed: 01/15/2023]
Abstract
Ferritins are ubiquitous and conserved proteins endowed with enzymatic ferroxidase activity, that oxidize Fe(II) ions at the dimetal ferroxidase centre to form a mineralized Fe(III) oxide core deposited within the apo-protein shell. Herein, the in vitro formation of a heterodimetal cofactor constituted by Fe and Mn ions has been investigated in human H ferritin (hHFt). Namely, Mn and Fe binding at the hHFt ferroxidase centre and its effects on Fe(II) oxidation have been investigated by UV-Vis ferroxidation kinetics, fluorimetric titrations, multifrequency EPR, and preliminary Mössbauer spectroscopy. Our results show that in hHFt, both Fe(II) and Mn(II) bind the ferroxidase centre forming a Fe-Mn cofactor. Moreover, molecular oxygen seems to favour Mn(II) binding and increases the ferroxidation activity of the Mn-loaded protein. The data suggest that Mn influences the Fe binding and the efficiency of the ferroxidation reaction. The higher efficiency of the Mn-Fe heterometallic centre may have a physiological relevance in specific cell types (i.e. glia cells), where the concentration of Mn is the same order of magnitude as iron.
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Affiliation(s)
- Matteo Ardini
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Barry D Howes
- INSTM, Department of Chemistry "U. Schiff", University of Florence, Via della Lastruccia, 3-13 50019 Sesto Fiorentino, Florence, Italy
| | - Annarita Fiorillo
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Elisabetta Falvo
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; CNR-Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Silvia Sottini
- INSTM, Department of Chemistry "U. Schiff", University of Florence, Via della Lastruccia, 3-13 50019 Sesto Fiorentino, Florence, Italy
| | - Donella Rovai
- INSTM, Department of Chemistry "U. Schiff", University of Florence, Via della Lastruccia, 3-13 50019 Sesto Fiorentino, Florence, Italy
| | - Marco Lantieri
- ISC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence, Italy
| | - Andrea Ilari
- CNR-Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Dante Gatteschi
- INSTM, Department of Chemistry "U. Schiff", University of Florence, Via della Lastruccia, 3-13 50019 Sesto Fiorentino, Florence, Italy
| | - Gabriele Spina
- INSTM, Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Florence, Italy
| | - Emilia Chiancone
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; CNR-Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Simonetta Stefanini
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
| | - Maria Fittipaldi
- INSTM, Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Florence, Italy.
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24
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Stoian SA, Peng YR, Beedle CC, Chung YJ, Lee GH, Yang EC, Hill S. Structural, Spectroscopic, and Theoretical Investigation of a T-Shaped [Fe 3(μ 3-O)] Cluster. Inorg Chem 2017; 56:10861-10874. [PMID: 28845975 DOI: 10.1021/acs.inorgchem.7b00455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The synthesis, X-ray crystal and electronic structures of [Fe3(μ3-O)(mpmae)2(OAc)2 Cl3], 1, where mpmae-H = 2-(N-methyl-N-((pyridine-2-yl)methyl)amino)ethanol, are described. This cluster comprises three high-spin ferric ions and exhibits a T-shaped site topology. Variable-frequency electron paramagnetic resonance measurements performed on single crystals of 1 demonstrate a total spin ST = 5/2 ground state, characterized by a small, negative, and nearly axial zero-field splitting tensor D = -0.49 cm-1, E/D ≈ 0.055. Analysis of magnetic susceptibility, magnetization, and magneto-structural correlations further corroborate the presence of a sextet ground-spin state. The observed ground state originates from the strong anti-ferromagnetic interaction of two iron(III) spins, with J = 115(5) cm-1, that, in turn, are only weakly coupled to the spin of the third site, with j = 7(1) cm-1. These exchange interactions lead to a ground state with magnetic properties that are essentially entirely determined by the weakly coupled site. The contributions of the individual spins to the total ground state of the cluster were monitored using variable-field 57Fe Mössbauer spectroscopy. Field-dependent spectra reveal that, while one of the iron sites exhibits a large negative internal field, typical of ferric ions, the other two sites exhibit small, but not null, negative and positive internal fields. A theoretical analysis reveals that these small internal fields originate from the mixing of the lowest ST = 5/2 excited state into the ground state which, in turn, is induced by a minute structural distortion.
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Affiliation(s)
| | - Yi-Ru Peng
- Department of Chemistry, Fu Jen Catholic University , Hsinchuang, New Taipei City, 24205 Taiwan, Republic of China
| | | | - Yi-Jung Chung
- Department of Chemistry, Fu Jen Catholic University , Hsinchuang, New Taipei City, 24205 Taiwan, Republic of China
| | - Gene-Hsiang Lee
- Instrumentation Centre, College of Science, National Taiwan University , Taipei, 106 Taiwan, Republic of China
| | - En-Che Yang
- Department of Chemistry, Fu Jen Catholic University , Hsinchuang, New Taipei City, 24205 Taiwan, Republic of China
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25
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Honarmand Ebrahimi K, Bill E, Hagedoorn P, Hagen WR. Spectroscopic evidence for the presence of a high-valent Fe(IV) species in the ferroxidase reaction of an archaeal ferritin. FEBS Lett 2017; 591:1712-1719. [PMID: 28542723 PMCID: PMC5519934 DOI: 10.1002/1873-3468.12697] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/10/2017] [Accepted: 05/21/2017] [Indexed: 12/20/2022]
Abstract
A high‐valent Fe(IV) species is proposed to be generated from the decay of a peroxodiferric intermediate in the catalytic cycle at the di‐iron cofactor center of dioxygen‐activating enzymes such as methane monooxygenase. However, it is believed that this intermediate is not formed in the di‐iron substrate site of ferritin, where oxidation of Fe(II) substrate to Fe(III) (the ferroxidase reaction) occurs also via a peroxodiferric intermediate. In opposition to this generally accepted view, here we present evidence for the occurrence of a high‐valent Fe(IV) in the ferroxidase reaction of an archaeal ferritin, which is based on trapped intermediates obtained with the freeze‐quench technique and combination of spectroscopic characterization. We hypothesize that a Fe(IV) intermediate catalyzes oxidation of excess Fe(II) nearby the ferroxidase center.
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Affiliation(s)
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion (MPI‐CEC)MülheimGermany
| | | | - Wilfred R. Hagen
- Department of BiotechnologyDelft University of TechnologyThe Netherlands
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26
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Abstract
Iron is very important in many biological processes and the ferritin protein family has evolved to store iron and to maintain cellular iron homeostasis. The deletion of the coding gene for the H subunit of ferritin leads to early embryonic death in mice and mutations in the gene for the L subunits in humans has been observed in neurodegenerative diseases, such as neuroferritinopathy. Thus, understanding how ferritin works is imperative and many studies have been conducted to delineate the molecular mechanism of ferritins and bacterioferritins. In the ferritin protein family, it is clear that a catalytic center for iron oxidation, the routes for iron to reach this center and the ability to nucleate an iron core, are common requirements for all ferritins. However, there are differences in the structural and mechanistic details of iron oxidation and mineralization. Although a common mechanism has been proposed for all ferritins, this mechanism needs to be further explored. There is a mechanistic diversity related to structural variation in the ferritin protein family. It is clear that other factors appear to affect the mechanism of iron oxidation and mineralization. This review focusses on the structural features of the ferritin protein family and its role in the mechanism of iron mineralization.
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Affiliation(s)
- Alejandro Yévenes
- Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile.
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27
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Bradley JM, Le Brun NE, Moore GR. Ferritins: furnishing proteins with iron. J Biol Inorg Chem 2016; 21:13-28. [PMID: 26825805 PMCID: PMC4771812 DOI: 10.1007/s00775-016-1336-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/06/2016] [Indexed: 12/04/2022]
Abstract
Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores, consider how iron might be released from ferritins, and examine in detail how three selected ferritins oxidise Fe2+ to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins.
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Affiliation(s)
- Justin M Bradley
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Geoffrey R Moore
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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28
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Sato D, Takebe S, Kurobe A, Ohtomo H, Fujiwara K, Ikeguchi M. Electrostatic Repulsion during Ferritin Assembly and Its Screening by Ions. Biochemistry 2016; 55:482-8. [DOI: 10.1021/acs.biochem.5b01197] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Daisuke Sato
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Satsuki Takebe
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Atsushi Kurobe
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Hideaki Ohtomo
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Kazuo Fujiwara
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Masamichi Ikeguchi
- Department of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
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29
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Sato D, Ohtomo H, Yamada Y, Hikima T, Kurobe A, Fujiwara K, Ikeguchi M. Ferritin Assembly Revisited: A Time-Resolved Small-Angle X-ray Scattering Study. Biochemistry 2016; 55:287-93. [DOI: 10.1021/acs.biochem.5b01152] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Daisuke Sato
- Department
of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Hideaki Ohtomo
- Department
of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Yoshiteru Yamada
- SPring-8, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5189, Japan
| | - Takaaki Hikima
- RIKEN SPring-8 Center, 1-1-1
Kouto, Sayo, Hyogo 679-5148, Japan
| | - Atsushi Kurobe
- Department
of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Kazuo Fujiwara
- Department
of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Masamichi Ikeguchi
- Department
of Bioinformatics, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
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30
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Ohtomo H, Ohtomo M, Sato D, Kurobe A, Sunato A, Matsumura Y, Kihara H, Fujiwara K, Ikeguchi M. A Physicochemical and Mutational Analysis of Intersubunit Interactions of Escherichia coli Ferritin A. Biochemistry 2015; 54:6243-51. [PMID: 26399896 DOI: 10.1021/acs.biochem.5b00723] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ferritin A from Escherichia coli (EcFtnA) is 24-meric protein, which forms spherical cagelike structures called nanocages. The nanocage structure is stabilized by the interface around 4-, 3-, and 2-fold symmetric axes. The subunit structure of EcFtnA comprises a four-helix bundle (helices A-D) and an additional helix E, which forms a 4-fold axis. In this study, we examined the contribution of the interface around three symmetric axes. pH-induced dissociation experiments monitored by analytical ultracentrifugation and small-angle X-ray scattering showed that the dimer related by 2-fold symmetry is the most stable unit. Mutations located near the 3-fold axis revealed that the contribution of each interaction was small. A mutant lacking helix E at the 4-fold axis formed a nanocage, suggesting that helix E is not essential for nanocage formation. Further truncation of the C-terminus of helix D abrogated the formation of the nanocage, suggesting that a few residues located at the C-terminus of helix D are critical for this process. These properties are similar to those known for mammalian ferritins and seem to be common principles for nanocage formation. The difference between EcFtnA and mammalian ferritins was that helix E-truncated EcFtnA maintained an iron-incorporating ability, whereas mammalian mutants lost it.
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Affiliation(s)
- Hideaki Ohtomo
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Mio Ohtomo
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Daisuke Sato
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Atsushi Kurobe
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Ayumi Sunato
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Yoshitaka Matsumura
- Department of Physics, Kansai Medical University , 18-89 Uyama-Higashi, Hirakata 573-1136, Japan
| | - Hiroshi Kihara
- Department of Physics, Kansai Medical University , 18-89 Uyama-Higashi, Hirakata 573-1136, Japan
| | - Kazuo Fujiwara
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Masamichi Ikeguchi
- Department of Bioinformatics, Soka University , 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
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31
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Pozzi C, Di Pisa F, Bernacchioni C, Ciambellotti S, Turano P, Mangani S. Iron binding to human heavy-chain ferritin. ACTA ACUST UNITED AC 2015; 71:1909-20. [PMID: 26327381 DOI: 10.1107/s1399004715013073] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 07/07/2015] [Indexed: 11/10/2022]
Abstract
Maxi-ferritins are ubiquitous iron-storage proteins with a common cage architecture made up of 24 identical subunits of five α-helices that drive iron biomineralization through catalytic iron(II) oxidation occurring at oxidoreductase sites (OS). Structures of iron-bound human H ferritin were solved at high resolution by freezing ferritin crystals at different time intervals after exposure to a ferrous salt. Multiple binding sites were identified that define the iron path from the entry ion channels to the oxidoreductase sites. Similar data are available for another vertebrate ferritin: the M protein from Rana catesbeiana. A comparative analysis of the iron sites in the two proteins identifies new reaction intermediates and underlines clear differences in the pattern of ligands that define the additional iron sites that precede the oxidoreductase binding sites along this path. Stopped-flow kinetics assays revealed that human H ferritin has different levels of activity compared with its R. catesbeiana counterpart. The role of the different pattern of transient iron-binding sites in the OS is discussed with respect to the observed differences in activity across the species.
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Affiliation(s)
- Cecilia Pozzi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Flavio Di Pisa
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Caterina Bernacchioni
- Dipartimento di Chimica, Università di Firenze, Via Della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy
| | - Silvia Ciambellotti
- Dipartimento di Chimica, Università di Firenze, Via Della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy
| | - Paola Turano
- Dipartimento di Chimica, Università di Firenze, Via Della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy
| | - Stefano Mangani
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via Aldo Moro 2, 53100 Siena, Italy
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32
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Iron management and production of electricity by microorganisms. Appl Microbiol Biotechnol 2015; 99:8329-36. [DOI: 10.1007/s00253-015-6897-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/27/2015] [Accepted: 07/30/2015] [Indexed: 10/23/2022]
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33
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The C-terminal regions have an important role in the activity of the ferroxidase center and the stability of Chlorobium tepidum ferritin. Protein J 2014; 33:211-20. [PMID: 24609571 DOI: 10.1007/s10930-014-9552-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The recombinant Chlorobium tepidum ferritin (rCtFtn) is able to oxidize iron using ferroxidase activity but its ferroxidase activity is intermediate between the H-chain human ferritin and the L-chain human ferritin. The rCtFtn has an unusual C-terminal region composed of 12 histidine residues, as well as aspartate and glutamate residues. These residues act as potential metal ion ligands, and the rCtFtn homology model predicts that this region projects inside the protein cage. The rCtFtn also lacks a conserved Tyr residue in position 19. In order to know if those differences are responsible for the altered ferroxidase properties of rCtFtn, we introduced by site-directed mutagenesis a stop codon at position 166 and a Tyr residue replaced Ala19 in the gene of rCtFtn (rCtFtn 166). The rCtFtn166 keeps the canonical sequence considered important for the activity of this family of proteins. Therefore, we expected that rCtFtn 166 would possess similar properties to those described for this protein family. The rCtFtn 166 is able to bind, oxidize and store iron; and its activity is inhibit by Zn(II) as was described for other ferritins. However, the rCtFtn 166 possesses a decrease ferroxidase activity and protein stability compared with the wild type rCtFtn. The analysis of the Ala19Tyr rCtFtn shows that this change does not affect the kinetic of iron oxidation. Therefore, these results indicate that the C-terminal regions have an important role in the activity of the ferroxidase center and the stability of rCtFtn.
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34
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Wong SG, Grigg JC, Le Brun NE, Moore GR, Murphy MEP, Mauk AG. The B-type channel is a major route for iron entry into the ferroxidase center and central cavity of bacterioferritin. J Biol Chem 2014; 290:3732-9. [PMID: 25512375 PMCID: PMC4319037 DOI: 10.1074/jbc.m114.623082] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Bacterioferritin is a bacterial iron storage and detoxification protein that is capable of forming a ferric oxyhydroxide mineral core within its central cavity. To do this, iron must traverse the bacterioferritin protein shell, which is expected to occur through one or more of the channels through the shell identified by structural studies. The size and negative electrostatic potential of the 24 B-type channels suggest that they could provide a route for iron into bacterioferritin. Residues at the B-type channel (Asn-34, Glu-66, Asp-132, and Asp-139) of E. coli bacterioferritin were substituted to determine if they are important for iron core formation. A significant decrease in the rates of initial oxidation of Fe(II) at the ferroxidase center and subsequent iron mineralization was observed for the D132F variant. The crystal structure of this variant shows that substitution of residue 132 with phenylalanine caused a steric blockage of the B-type channel and no other material structural perturbation. We conclude that the B-type channel is a major route for iron entry into both the ferroxidase center and the iron storage cavity of bacterioferritin.
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Affiliation(s)
- Steve G Wong
- From the Department of Biochemistry and Molecular Biology, the Centre for Blood Research and
| | - Jason C Grigg
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Michael E P Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - A Grant Mauk
- From the Department of Biochemistry and Molecular Biology, the Centre for Blood Research and
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35
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Honarmand Ebrahimi K, Hagedoorn PL, Hagen WR. Unity in the Biochemistry of the Iron-Storage Proteins Ferritin and Bacterioferritin. Chem Rev 2014; 115:295-326. [DOI: 10.1021/cr5004908] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Kourosh Honarmand Ebrahimi
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628
BC Delft, The Netherlands
| | - Peter-Leon Hagedoorn
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628
BC Delft, The Netherlands
| | - Wilfred R. Hagen
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628
BC Delft, The Netherlands
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36
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Thiruselvam V, Sivaraman P, Kumarevel T, Ponnuswamy MN. Revelation of endogenously bound Fe(2+) ions in the crystal structure of ferritin from Escherichia coli. Biochem Biophys Res Commun 2014; 453:636-41. [PMID: 25305494 DOI: 10.1016/j.bbrc.2014.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 10/02/2014] [Indexed: 11/29/2022]
Abstract
Ferritin is an iron regulatory protein. It is responsible for storage and detoxification of excess iron thereby it regulates iron level in the body. Here we report the crystal structure of ferritin with two endogenously expressed Fe atoms binding in both the sites. The protein was purified and characterized by MALDI-TOF and N-terminal amino acid sequencing. The crystal belongs to I4 space group and it diffracted up to 2.5Å. The structural analysis suggested that it crystallizes as hexamer and confirmed that it happened to be the first report of endogenously expressed Fe ions incorporated in both the A and B sites, situated in between the helices.
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Affiliation(s)
- Viswanathan Thiruselvam
- Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India
| | - Padavattan Sivaraman
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Thirumananseri Kumarevel
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Structural Biology Laboratory, RIKEN Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
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37
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Arenas-Salinas M, Townsend PD, Brito C, Marquez V, Marabolli V, Gonzalez-Nilo F, Matias C, Watt RK, López-Castro JD, Domínguez-Vera J, Pohl E, Yévenes A. The crystal structure of ferritin from Chlorobium tepidum reveals a new conformation of the 4-fold channel for this protein family. Biochimie 2014; 106:39-47. [PMID: 25079050 DOI: 10.1016/j.biochi.2014.07.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 07/18/2014] [Indexed: 12/19/2022]
Abstract
Ferritins are ubiquitous iron-storage proteins found in all kingdoms of life. They share a common architecture made of 24 subunits of five α-helices. The recombinant Chlorobium tepidum ferritin (rCtFtn) is a structurally interesting protein since sequence alignments with other ferritins show that this protein has a significantly extended C-terminus, which possesses 12 histidine residues as well as several aspartate and glutamic acid residues that are potential metal ion binding residues. We show that the macromolecular assembly of rCtFtn exhibits a cage-like hollow shell consisting of 24 monomers that are related by 4-3-2 symmetry; similar to the assembly of other ferritins. In all ferritins of known structure the short fifth α-helix adopts an acute angle with respect to the four-helix bundle. However, the crystal structure of the rCtFtn presented here shows that this helix adopts a new conformation defining a new assembly of the 4-fold channel of rCtFtn. This conformation allows the arrangement of the C-terminal region into the inner cavity of the protein shell. Furthermore, two Fe(III) ions were found in each ferroxidase center of rCtFtn, with an average FeA-FeB distance of 3 Å; corresponding to a diferric μ-oxo/hydroxo species. This is the first ferritin crystal structure with an isolated di-iron center in an iron-storage ferritin. The crystal structure of rCtFtn and the biochemical results presented here, suggests that rCtFtn presents similar biochemical properties reported for other members of this protein family albeit with distinct structural plasticity.
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Affiliation(s)
- Mauricio Arenas-Salinas
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Philip D Townsend
- Department of Chemistry & School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
| | - Christian Brito
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Santiago, Chile
| | - Valeria Marquez
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Santiago, Chile
| | - Vanessa Marabolli
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Santiago, Chile
| | - Fernando Gonzalez-Nilo
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Santiago, Chile
| | - Cata Matias
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - Richard K Watt
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - Juan D López-Castro
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - José Domínguez-Vera
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Ehmke Pohl
- Department of Chemistry & School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
| | - Alejandro Yévenes
- Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile.
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38
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Bradley JM, Moore GR, Le Brun NE. Mechanisms of iron mineralization in ferritins: one size does not fit all. J Biol Inorg Chem 2014; 19:775-85. [PMID: 24748222 DOI: 10.1007/s00775-014-1136-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 04/07/2014] [Indexed: 12/23/2022]
Abstract
Significant progress has been made in recent years toward understanding the processes by which an iron mineral is deposited within members of the ferritin family of 24mer iron storage proteins, enabled by high-resolution structures together with spectroscopic and kinetic studies. These suggest common characteristics that are shared between ferritins, namely, a highly symmetric arrangement of subunits that provides a protein coat around a central cavity in which the mineral is formed, channels through the coat that facilitate ingress and egress of ions, and catalytic sites, called ferroxidase centers, that drive Fe(2+) oxidation. They also reveal significant variations in both structure and mechanism amongst ferritins. Here, we describe three general types of structurally distinct ferroxidase center and the mechanisms of mineralization that they are associated with. The highlighted variation leads us to conclude that there is no universal mechanism by which ferritins function, but instead there exists several distinct mechanisms of ferritin iron mineralization.
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Affiliation(s)
- Justin M Bradley
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, NR4 7TJ, UK
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39
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Lv C, Zhang S, Zang J, Zhao G, Xu C. Four-fold channels are involved in iron diffusion into the inner cavity of plant ferritin. Biochemistry 2014; 53:2232-41. [PMID: 24678690 DOI: 10.1021/bi500066m] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
From an evolutionary point of view, plant and animal ferritins arose from a common ancestor, but plant ferritin exhibits different features as compared with the animal analogue. One major difference is that the 4-fold channels naturally occurring in plant ferritin are hydrophilic, whereas the 4-fold channels in animal ferritin are hydrophobic. Prior to this study, however, the function of the 4-fold channels in oxidative deposition of iron in phytoferritin remained unknown. To elucidate the role of the 4-fold channels in iron oxidative deposition in ferritin, three mutants of recombinant soybean seed H-2 ferritin (rH-2) were prepared by site-directed mutagenesis, which contained H193A/H197A, a 4-fold channel mutant, E165I/E167A/E171A, a 3-fold channel mutant, and E165I/E167A/E171A/H193A/H197A, where both 3- and 4-channels were mutated. Stopped-flow, electrode oximetry, and transmission electron microscopy (TEM) results showed that H193A/H197A and E165I/E167A/E171A exhibited a similar catalyzing activity of iron oxidation with each other, but a pronounced low activity compared to rH-2, demonstrating that both the 4-fold and 3-fold hydrophilic channels are necessary for iron diffusion in ferritin, followed by oxidation. Indeed, among all tested ferritin, the catalyzing activity of E165I/E167A/E171A/H193A/H197A was weakest because its 3- and 4- fold channels were blocked. These findings advance our understanding of the function of 4-fold channels of plant ferritin and the relationship of the structure and function of ferritin.
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Affiliation(s)
- Chenyan Lv
- CAU & ACC Joint-Laboratory of Space Food, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources , Beijing 100083, China
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40
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Bou-Abdallah F, Yang H, Awomolo A, Cooper B, Woodhall MR, Andrews SC, Chasteen ND. Functionality of the three-site ferroxidase center of Escherichia coli bacterial ferritin (EcFtnA). Biochemistry 2014; 53:483-95. [PMID: 24380371 DOI: 10.1021/bi401517f] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
At least three ferritins are found in the bacterium Escherichia coli : the heme-containing bacterioferritin (EcBFR) and two nonheme bacterial ferritins (EcFtnA and EcFtnB). In addition to the conserved A and B sites of the diiron ferroxidase center, EcFtnA has a third iron-binding site (the C site) of unknown function that is nearby the diiron site. In the present work, the complex chemistry of iron oxidation and deposition in EcFtnA was further defined through a combination of oximetry, pH stat, stopped-flow and conventional kinetics, UV-vis, fluorescence, and EPR spectroscopic measurements on both the wild-type protein and site-directed variants of the A, B, and C sites. The data reveal that although H2O2 is a product of dioxygen reduction in EcFtnA and oxidation occurs with a stoichiometry of Fe(2+)/O2 ∼ 3:1 most of the H2O2 produced is consumed in subsequent reactions with a 2:1 Fe(2+)/H2O2 stoichiometry, thus suppressing hydroxyl-radical formation. Although the A and B sites are essential for rapid iron oxidation, the C site slows oxidation and suppresses iron turnover at the ferroxidase center. A tyrosyl radical, assigned to Tyr24 near the ferroxidase center, is formed during iron oxidation, and its possible significance to the function of the protein is discussed. Taken as a whole, the data indicate that there are multiple iron-oxidation pathways in EcFtnA with O2 and H2O2 as oxidants. Furthermore, our data do not support a universal mechanism for iron oxidation in all ferritins whereby the C site acts as transit site, as has been recently proposed.
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Affiliation(s)
- F Bou-Abdallah
- Department of Chemistry, State University of New York , Potsdam, New York 13676, United States
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41
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Carmona F, Palacios Ò, Gálvez N, Cuesta R, Atrian S, Capdevila M, Domínguez-Vera JM. Ferritin iron uptake and release in the presence of metals and metalloproteins: Chemical implications in the brain. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2013.03.034] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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42
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Ebrahimi KH, Hagedoorn PL, Hagen WR. A Conserved Tyrosine in Ferritin Is a Molecular Capacitor. Chembiochem 2013; 14:1123-33. [DOI: 10.1002/cbic.201300149] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Indexed: 11/06/2022]
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43
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Pfaffen S, Abdulqadir R, Le Brun NE, Murphy MEP. Mechanism of ferrous iron binding and oxidation by ferritin from a pennate diatom. J Biol Chem 2013; 288:14917-25. [PMID: 23548912 PMCID: PMC3663513 DOI: 10.1074/jbc.m113.454496] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A novel ferritin was recently found in Pseudo-nitzschia multiseries (PmFTN), a marine pennate diatom that plays a major role in global primary production and carbon sequestration into the deep ocean. Crystals of recombinant PmFTN were soaked in iron and zinc solutions, and the structures were solved to 1.65–2.2-Å resolution. Three distinct iron binding sites were identified as determined from anomalous dispersion data from aerobically grown ferrous soaked crystals. Sites A and B comprise the conserved ferroxidase active site, and site C forms a pathway leading toward the central cavity where iron storage occurs. In contrast, crystal structures derived from anaerobically grown and ferrous soaked crystals revealed only one ferrous iron in the active site occupying site A. In the presence of dioxygen, zinc is observed bound to all three sites. Iron oxidation experiments using stopped-flow absorbance spectroscopy revealed an extremely rapid phase corresponding to Fe(II) oxidation at the ferroxidase site, which is saturated after adding 48 ferrous iron to apo-PmFTN (two ferrous iron per subunit), and a much slower phase due to iron core formation. These results suggest an ordered stepwise binding of ferrous iron and dioxygen to the ferroxidase site in preparation for catalysis and a partial mobilization of iron from the site following oxidation.
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Affiliation(s)
- Stephanie Pfaffen
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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44
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Khare G, Nangpal P, Tyagi AK. Unique Residues at the 3-Fold and 4-Fold Axis of Mycobacterial Ferritin Are Involved in Oligomer Switching. Biochemistry 2013; 52:1694-704. [DOI: 10.1021/bi301189t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Garima Khare
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi
110021, India
| | - Prachi Nangpal
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi
110021, India
| | - Anil K. Tyagi
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi
110021, India
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45
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Abstract
Ferritins, highly symmetrical protein nanocages, are reactors for Fe2+ and dioxygen or hydrogen peroxide that are found in all kingdoms of life and in many different cells of multicellular organisms. They synthesize iron concentrates required for cells to make cofactors of iron proteins (heme, FeS, mono and diiron). The caged ferritin biominerals, Fe2O3•H2O are also antioxidants, acting as sinks for iron and oxidants scavenged from damaged proteins; genetic regulation of ferritin biosynthesis is sensitive to both iron and oxidants. Here, the emphasis here is ferritin oxidoreductase chemistry, ferritin ion channels for Fe 2+ transit into and out of the protein cage and Fe 3+ O mineral nucleation, and uses of ferritin cages in nanocatalysis and nanomaterial synthesis. The Fe2+ and O ferritin protein reactors, likely critical in the transition from anaerobic to aerobic life on earth, play central, contemporary roles that balance iron and oxygen chemistry in biology and have emerging roles in nanotechnology.
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Affiliation(s)
- Elizabeth C. Theil
- Children’s Hospital Oakland Research Institute, University of California, Berkeley
- Department of Nutritional Science and Toxicology, University of California, Berkeley
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46
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Bikas R, Hosseini-Monfared H, Zoppellaro G, Herchel R, Tucek J, Owczarzak AM, Kubicki M, Zboril R. Synthesis, structure, magnetic properties and theoretical calculations of methoxy bridged dinuclear iron(iii) complex with hydrazone based O,N,N-donor ligand. Dalton Trans 2013; 42:2803-12. [DOI: 10.1039/c2dt31751f] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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47
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Honarmand Ebrahimi K, Bill E, Hagedoorn PL, Hagen WR. The catalytic center of ferritin regulates iron storage via Fe(II)-Fe(III) displacement. Nat Chem Biol 2012; 8:941-8. [DOI: 10.1038/nchembio.1071] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 08/07/2012] [Indexed: 12/15/2022]
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48
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Abstract
Dps proteins are the structural relatives of bacterioferritins and ferritins ubiquitously present in the bacterial and archaeal kingdoms. The ball-shaped enzymes play important roles in the detoxification of ROS (reactive oxygen species), in iron scavenging to prevent Fenton reactions and in the mechanical protection of DNA. Detoxification of ROS and iron chaperoning represent the most archetypical functions of dodecameric Dps enzymes. Recent crystallographic studies of these dodecameric complexes have unravelled species-dependent mechanisms of iron uptake into the hollow spheres. Subsequent functions in iron oxidation at ferroxidase centres are highly conserved among bacteria. Final nucleation of iron as iron oxide nanoparticles has been demonstrated to originate at acidic residues located on the inner surface. Some Dps enzymes are also implicated in newly observed catalytic functions related to the formation of molecules playing roles in bacterium–host cell communication. Most recently, Dps complexes are attracting attention in semiconductor science as biomimetic tools for the technical production of the smallest metal-based quantum nanodots used in nanotechnological approaches, such as memory storage or solar cell development.
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49
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Pereira AS, Timóteo CG, Guilherme M, Folgosa F, Naik SG, Duarte AG, Huynh BH, Tavares P. Spectroscopic evidence for and characterization of a trinuclear ferroxidase center in bacterial ferritin from Desulfovibrio vulgaris Hildenborough. J Am Chem Soc 2012; 134:10822-32. [PMID: 22681596 PMCID: PMC3390943 DOI: 10.1021/ja211368u] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ferritins are ubiquitous and can be found in practically all organisms that utilize Fe. They are composed of 24 subunits forming a hollow sphere with an inner cavity of ~80 Å in diameter. The main function of ferritin is to oxidize the cytotoxic Fe(2+) ions and store the oxidized Fe in the inner cavity. It has been established that the initial step of rapid oxidation of Fe(2+) (ferroxidation) by H-type ferritins, found in vertebrates, occurs at a diiron binding center, termed the ferroxidase center. In bacterial ferritins, however, X-ray crystallographic evidence and amino acid sequence analysis revealed a trinuclear Fe binding center comprising a binuclear Fe binding center (sites A and B), homologous to the ferroxidase center of H-type ferritin, and an adjacent mononuclear Fe binding site (site C). In an effort to obtain further evidence supporting the presence of a trinuclear Fe binding center in bacterial ferritins and to gain information on the states of the iron bound to the trinuclear center, bacterial ferritin from Desulfovibrio vulgaris (DvFtn) and its E130A variant was loaded with substoichiometric amounts of Fe(2+), and the products were characterized by Mössbauer and EPR spectroscopy. Four distinct Fe species were identified: a paramagnetic diferrous species, a diamagnetic diferrous species, a mixed valence Fe(2+)Fe(3+) species, and a mononuclear Fe(2+) species. The latter three species were detected in the wild-type DvFtn, while the paramagnetic diferrous species was detected in the E130A variant. These observations can be rationally explained by the presence of a trinuclear Fe binding center, and the four Fe species can be properly assigned to the three Fe binding sites. Further, our spectroscopic data suggest that (1) the fully occupied trinuclear center supports an all ferrous state, (2) sites B and C are bridged by a μ-OH group forming a diiron subcenter within the trinuclear center, and (3) this subcenter can afford both a mixed valence Fe(2+)Fe(3+) state and a diferrous state. Mechanistic insights provided by these new findings are discussed and a minimal mechanistic scheme involving O-O bond cleavage is proposed.
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Affiliation(s)
- Alice S. Pereira
- Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
| | - Cristina G. Timóteo
- Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
| | - Márcia Guilherme
- Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
| | - Filipe Folgosa
- Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
| | - Sunil G. Naik
- Department of Physics, Emory University, Atlanta, GA 30322, USA
| | - Américo G. Duarte
- Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
| | - Boi Hanh Huynh
- Department of Physics, Emory University, Atlanta, GA 30322, USA
| | - Pedro Tavares
- Requimte/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
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Ebrahimi KH, Hagedoorn PL, van der Weel L, Verhaert PDEM, Hagen WR. A novel mechanism of iron-core formation by Pyrococcus furiosus archaeoferritin, a member of an uncharacterized branch of the ferritin-like superfamily. J Biol Inorg Chem 2012; 17:975-85. [PMID: 22739810 PMCID: PMC3401498 DOI: 10.1007/s00775-012-0913-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 06/05/2012] [Indexed: 10/28/2022]
Abstract
Storage of iron in a nontoxic and bioavailable form is essential for many forms of life. Three subfamilies of the ferritin-like superfamily, namely, ferritin, bacterioferritin, and Dps (DNA-binding proteins from starved cells), are able to store iron. Although the function of these iron-storage proteins is constitutive to many organisms to sustain life, the genome of some organisms appears not to encode any of these proteins. In an attempt to identify new iron-storage systems, we have found and characterized a new member of the ferritin-like superfamily of proteins, which unlike the multimeric storage system of ferritin, bacterioferritin, and Dps is monomeric in the absence of iron. Monomers catalyze oxidation of Fe(II) and they store the Fe(III) product as they assemble to form structures comparable to those of 24-meric ferritin. We propose that this mechanism is an alternative method of iron storage by the ferritin-like superfamily of proteins in organisms that lack the regular preassociated 24-meric/12-meric ferritins.
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