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Eren E, Watts NR, Montecinos F, Wingfield PT. Encapsulated Ferritin-like Proteins: A Structural Perspective. Biomolecules 2024; 14:624. [PMID: 38927029 PMCID: PMC11202242 DOI: 10.3390/biom14060624] [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: 04/29/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
Encapsulins are self-assembling nano-compartments that naturally occur in bacteria and archaea. These nano-compartments encapsulate cargo proteins that bind to the shell's interior through specific recognition sequences and perform various metabolic processes. Encapsulation enables organisms to perform chemical reactions without exposing the rest of the cell to potentially harmful substances while shielding cargo molecules from degradation and other adverse effects of the surrounding environment. One particular type of cargo protein, the ferritin-like protein (FLP), is the focus of this review. Encapsulated FLPs are members of the ferritin-like protein superfamily, and they play a crucial role in converting ferrous iron (Fe+2) to ferric iron (Fe+3), which is then stored inside the encapsulin in mineralized form. As such, FLPs regulate iron homeostasis and protect organisms against oxidative stress. Recent studies have demonstrated that FLPs have tremendous potential as biosensors and bioreactors because of their ability to catalyze the oxidation of ferrous iron with high specificity and efficiency. Moreover, they have been investigated as potential targets for therapeutic intervention in cancer drug development and bacterial pathogenesis. Further research will likely lead to new insights and applications for these remarkable proteins in biomedicine and biotechnology.
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Affiliation(s)
| | | | | | - Paul T. Wingfield
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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2
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Bradley JM, Bugg Z, Sackey A, Andrews SC, Wilson MT, Svistunenko DA, Moore GR, Le Brun NE. The Ferroxidase Centre of Escherichia coli Bacterioferritin Plays a Key Role in the Reductive Mobilisation of the Mineral Iron Core. Angew Chem Int Ed Engl 2024; 63:e202401379. [PMID: 38407997 DOI: 10.1002/anie.202401379] [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: 01/19/2024] [Revised: 02/22/2024] [Accepted: 02/22/2024] [Indexed: 02/28/2024]
Abstract
Ferritins are multimeric cage-forming proteins that play a crucial role in cellular iron homeostasis. All H-chain-type ferritins harbour a diiron site, the ferroxidase centre, at the centre of a 4 α-helical bundle, but bacterioferritins are unique in also binding 12 hemes per 24 meric assembly. The ferroxidase centre is known to be required for the rapid oxidation of Fe2+ during deposition of an immobilised ferric mineral core within the protein's hollow interior. In contrast, the heme of bacterioferritin is required for the efficient reduction of the mineral core during iron release, but has little effect on the rate of either oxidation or mineralisation of iron. Thus, the current view is that these two cofactors function in iron uptake and release, respectively, with no functional overlap. However, rapid electron transfer between the heme and ferroxidase centre of bacterioferritin from Escherichia coli was recently demonstrated, suggesting that the two cofactors may be functionally connected. Here we report absorbance and (magnetic) circular dichroism spectroscopies, together with in vitro assays of iron-release kinetics, which demonstrate that the ferroxidase centre plays an important role in the reductive mobilisation of the bacterioferritin mineral core, which is dependent on the heme-ferroxidase centre electron transfer pathway.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Zinnia Bugg
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Aaren Sackey
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Simon C Andrews
- School of Biological Sciences, University of Reading, Whiteknights, Reading, RG6 6AS, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
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3
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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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4
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Graham UM, Dozier AK, Feola DJ, Tseng MT, Yokel RA. Macrophage Polarization Status Impacts Nanoceria Cellular Distribution but Not Its Biotransformation or Ferritin Effects. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2298. [PMID: 37630884 PMCID: PMC10459093 DOI: 10.3390/nano13162298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 07/30/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023]
Abstract
The innate immune system is the first line of defense against external threats through the initiation and regulation of inflammation. Macrophage differentiation into functional phenotypes influences the fate of nanomaterials taken up by these immune cells. High-resolution electron microscopy was used to investigate the uptake, distribution, and biotransformation of nanoceria in human and murine M1 and M2 macrophages in unprecedented detail. We found that M1 and M2 macrophages internalize nanoceria differently. M1-type macrophages predominantly sequester nanoceria near the plasma membrane, whereas nanoceria are more uniformly distributed throughout M2 macrophage cytoplasm. In contrast, both macrophage phenotypes show identical nanoceria biotransformation to cerium phosphate nanoneedles and simultaneous nanoceria with ferritin co-precipitation within the cells. Ferritin biomineralization is a direct response to nanoparticle uptake inside both macrophage phenotypes. We also found that the same ferritin biomineralization mechanism occurs after the uptake of Ce-ions into polarized macrophages and into unpolarized human monocytes and murine RAW 264.7 cells. These findings emphasize the need for evaluating ferritin biomineralization in studies that involve the internalization of nano objects, ranging from particles to viruses to biomolecules, to gain greater mechanistic insights into the overall immune responses to nano objects.
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Affiliation(s)
- Uschi M. Graham
- Pharmaceutical Sciences Department, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA;
| | - Alan K. Dozier
- National Institute of Occupational Safety and Health (NIOSH), Cincinnati, OH 45213-2515, USA;
| | - David J. Feola
- Pharmacy Practice and Science Department, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA;
| | - Michael T. Tseng
- Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40202, USA
| | - Robert A. Yokel
- Pharmaceutical Sciences Department, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA;
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5
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Shesh BP, Connor JR. A novel view of ferritin in cancer. Biochim Biophys Acta Rev Cancer 2023; 1878:188917. [PMID: 37209958 PMCID: PMC10330744 DOI: 10.1016/j.bbcan.2023.188917] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/13/2023] [Accepted: 05/13/2023] [Indexed: 05/22/2023]
Abstract
Since its discovery more than 85 years ago, ferritin has principally been known as an iron storage protein. However, new roles, beyond iron storage, are being uncovered. Novel processes involving ferritin such as ferritinophagy and ferroptosis and as a cellular iron delivery protein not only expand our thinking on the range of contributions of this protein but present an opportunity to target these pathways in cancers. The key question we focus on within this review is whether ferritin modulation represents a useful approach for treating cancers. We discussed novel functions and processes of this protein in cancers. We are not limiting this review to cell intrinsic modulation of ferritin in cancers, but also focus on its utility in the trojan horse approach in cancer therapeutics. The novel functions of ferritin as discussed herein realize the multiple roles of ferritin in cell biology that can be probed for therapeutic opportunities and further research.
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Affiliation(s)
| | - James R Connor
- Department of Neurosurgery, Penn State Hershey Medical Center, Hershey, PA, USA.
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6
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Babar TK, Glare TR, Hampton JG, Hurst MRH, Narciso J, Sheen CR, Koch B. Linocin M18 protein from the insect pathogenic bacterium Brevibacillus laterosporus isolates. Appl Microbiol Biotechnol 2023:10.1007/s00253-023-12563-8. [PMID: 37204448 DOI: 10.1007/s00253-023-12563-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 04/19/2023] [Accepted: 04/29/2023] [Indexed: 05/20/2023]
Abstract
Brevibacillus laterosporus (Bl) is a Gram-positive and spore-forming bacterium. Insect pathogenic strains have been characterised in New Zealand, and two isolates, Bl 1821L and Bl 1951, are under development for use in biopesticides. However, growth in culture is sometimes disrupted, affecting mass production. Based on previous work, it was hypothesised that Tectiviridae phages might be implicated. While investigating the cause of the disrupted growth, electron micrographs of crude lysates showed structural components of putative phages including capsid and tail-like structures. Sucrose density gradient purification yielded a putative self-killing protein of ~30 kDa. N-terminal sequencing of the ~30 kDa protein identified matches to a predicted 25 kDa hypothetical and a 31.4 kDa putative encapsulating protein homologs, with the genes encoding each protein adjacent in the genomes. BLASTp analysis of the homologs of 31.4 kDa amino acid sequences shared 98.6% amino acid identity to the Linocin M18 bacteriocin family protein of Brevibacterium sp. JNUCC-42. Bioinformatic tools including AMPA and CellPPD defined that the bactericidal potential originated from a putative encapsulating protein. Antagonistic activity of the ~30 kDa encapsulating protein of Bl 1821L and Bl 1951during growth in broth exhibited bacterial autolytic activity. LIVE/DEAD staining of Bl 1821L cells after treatment with the ~30 kDa encapsulating protein of Bl 1821L substantiated the findings by showing 58.8% cells with the compromised cell membranes as compared to 37.5% cells in the control. Furthermore, antibacterial activity of the identified proteins of Bl 1821L was validated through gene expression in a Gram-positive bacterium Bacillus subtilis WB800N. KEY POINTS: • Gene encoding the 31.4 kDa antibacterial Linocin M18 protein was identified • It defined the autocidal activity of Linocin M18 (encapsulating) protein • Identified the possible killing mechanism of the encapsulins.
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Affiliation(s)
- Tauseef K Babar
- Bio-Protection Research Centre, Lincoln University, Lincoln, Canterbury, 7647, New Zealand.
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, 60000, Pakistan.
| | - Travis R Glare
- Bio-Protection Research Centre, Lincoln University, Lincoln, Canterbury, 7647, New Zealand
- Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, Canterbury, 7647, New Zealand
| | - John G Hampton
- Bio-Protection Research Centre, Lincoln University, Lincoln, Canterbury, 7647, New Zealand
- Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, Canterbury, 7647, New Zealand
| | - Mark R H Hurst
- Resilient Agriculture, AgResearch, Lincoln Research Centre, Christchurch, New Zealand
| | - Josefina Narciso
- Bio-Protection Research Centre, Lincoln University, Lincoln, Canterbury, 7647, New Zealand
- Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, Canterbury, 7647, New Zealand
| | - Campbell R Sheen
- Protein Science and Engineering, Callaghan Innovation, Christchurch, New Zealand
| | - Barbara Koch
- Protein Science and Engineering, Callaghan Innovation, Christchurch, New Zealand
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7
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Masison J, Mendes P. Modeling the iron storage protein ferritin reveals how residual ferrihydrite iron determines initial ferritin iron sequestration kinetics. PLoS One 2023; 18:e0281401. [PMID: 36745660 PMCID: PMC9901743 DOI: 10.1371/journal.pone.0281401] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 01/22/2023] [Indexed: 02/07/2023] Open
Abstract
Computational models can be created more efficiently by composing them from smaller, well-defined sub-models that represent specific cellular structures that appear often in different contexts. Cellular iron metabolism is a prime example of this as multiple cell types tend to rely on a similar set of components (proteins and regulatory mechanisms) to ensure iron balance. One recurrent component, ferritin, is the primary iron storage protein in mammalian cells and is necessary for cellular iron homeostasis. Its ability to sequester iron protects cells from rising concentrations of ferrous iron limiting oxidative cell damage. The focus of the present work is establishing a model that tractably represents the ferritin iron sequestration kinetics such that it can be incorporated into larger cell models, in addition to contributing to the understanding of general ferritin iron sequestration dynamics within cells. The model's parameter values were determined from published kinetic and binding experiments and the model was validated against independent data not used in its construction. Simulation results indicate that FT concentration is the most impactful on overall sequestration dynamics, while the FT iron saturation (number of iron atoms sequestered per FT cage) fine tunes the initial rates. Finally, because this model has a small number of reactions and species, was built to represent important details of FT kinetics, and has flexibility to include subtle changes in subunit composition, we propose it to be used as a building block in a variety of specific cell type models of iron metabolism.
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Affiliation(s)
- Joseph Masison
- Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, United States of America
| | - Pedro Mendes
- Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Department of Cell Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
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8
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Parida A, Mohanty A, Raut RK, Padhy I, Behera RK. Modification of 4-Fold and B-Pores in Bacterioferritin from Mycobacterium tuberculosis Reveals Their Role in Fe 2+ Entry and Oxidoreductase Activity. Inorg Chem 2023; 62:178-191. [PMID: 36525578 DOI: 10.1021/acs.inorgchem.2c03156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The self-assembled ferritin nanocages, nature's solution to iron toxicity and its low solubility, scavenge free iron to synthesize hydrated ferric oxyhydroxide mineral inside their central cavity by protein-mediated ferroxidase and hydrolytic/nucleation reactions. These complex processes in ferritin commence with the rapid influx of Fe2+ ions via the inter-subunit contact points (i.e., pores/channels). Investigation of these pores as Fe2+ uptake routes in ferritins remains a subject of intense research, in iron metabolism, toxicity, and bacterial pathogenesis, which are yet to be established in the bacterioferritin (BfrA) from Mycobacterium tuberculosis (Mtb). The electrostatic properties of this protein indicate that the 4-fold and B-pores might serve as potential Fe2+ entry routes. Therefore, in the current work, electrostatics at/along these pores was altered by site-directed mutagenesis to establish their role in Fe2+ uptake/oxidation (ferroxidase activity) in Mtb BfrA. Despite forming self-assembled protein nanocompartment, these 4-fold and B-pore variants exhibited partial loss of ferroxidase activity and lower accumulation of transient species, which not only indicated their role in Fe2+ entry but also suggested the existence of multiple pathways. Although the B-pore variants inhibited the rapid ferroxidase activity to a larger extent, they had minimal impact on their cage stability. The current work revealed the relative contribution of these pores toward rapid Fe2+ uptake/oxidation and cage stability, possibly as consequences of their differential symmetry, number of modified residues (at each pore), and heme content. Therefore, these findings may help to understand the role of these pores in iron acquisition and Mtb proliferation under iron-limiting conditions to control its pathogenesis.
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Affiliation(s)
- Akankshika Parida
- Department of Chemistry, National Institute of Technology, Rourkela, 769008Odisha, India
| | - Abhinav Mohanty
- Department of Chemistry, National Institute of Technology, Rourkela, 769008Odisha, India
| | - Rohit Kumar Raut
- Department of Chemistry, National Institute of Technology, Rourkela, 769008Odisha, India
| | - Ipsita Padhy
- Department of Chemistry, National Institute of Technology, Rourkela, 769008Odisha, India
| | - Rabindra K Behera
- Department of Chemistry, National Institute of Technology, Rourkela, 769008Odisha, India
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9
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Parida A, Behera RK. Iron Accumulation in Ferritin. Methods Mol Biol 2023; 2671:121-134. [PMID: 37308642 DOI: 10.1007/978-1-0716-3222-2_7] [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: 06/14/2023]
Abstract
Understanding the iron accumulation process in ferritin protein nanocages has remained a centerpiece in the field of iron biochemistry/biomineralization, which ultimately has implications in health and diseases. Although mechanistic differences of iron acquisition and mineralization exist in the superfamily of ferritins, we describe the techniques that can be used to investigate the accumulation of iron in all the ferritin proteins by in vitro iron mineralization process. In this chapter, we report that the non-denaturing polyacrylamide gel electrophoresis coupled with Prussian blue staining (in-gel assay) can be useful to investigate the iron-loading efficiency in ferritin protein nanocage, by estimating the relative amount of iron incorporated inside it. Similarly, the absolute size of the iron mineral core and the amount of total iron accumulated inside its nanocavity can be determined by using transmission electron microscopy and spectrophotometry, respectively.
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Affiliation(s)
- Akankshika Parida
- Department of Chemistry, National Institute of Technology, Rourkela, Odisha, India
| | - Rabindra K Behera
- Department of Chemistry, National Institute of Technology, Rourkela, Odisha, India.
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10
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Bradley JM, Gray E, Richardson J, Moore GR, Le Brun NE. Protein encapsulation within the internal cavity of a bacterioferritin. NANOSCALE 2022; 14:12322-12331. [PMID: 35969005 PMCID: PMC9439638 DOI: 10.1039/d2nr01780f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The thermal and chemical stability of 24mer ferritins has led to attempts to exploit their naturally occurring nanoscale (8 nm) internal cavities for biotechnological applications. An area of increasing interest is the encapsulation of molecules either for medical or biocatalysis applications. Encapsulation requires ferritin dissociation, typically induced using high temperature or acidic conditions (pH ≥ 2), which generally precludes the inclusion of fragile cargo such as proteins or peptide fragments. Here we demonstrate that minimizing salt concentration combined with adjusting the pH to ≤8.5 (i.e. low proton/metal ion concentration) reversibly shifts the naturally occurring equilibrium between dimeric and 24meric assemblies of Escherichia coli bacterioferritin (Bfr) in favour of the disassembled form. Interconversion between the different oligomeric forms of Bfr is sufficiently slow under these conditions to allow the use of size exclusion chromatography to obtain wild type protein in the purely dimeric and 24meric forms. This control over association state was exploited to bind heme at natural sites that are not accessible in the assembled protein. The potential for biotechnological applications was demonstrated by the encapsulation of a small, acidic [3Fe-4S] cluster-containing ferredoxin within the Bfr internal cavity. The capture of ∼4-6 negatively charged ferredoxin molecules per cage indicates that charge complementarity with the inner protein surface is not an essential determinant of successful encapsulation.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Elizabeth Gray
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Jake Richardson
- Bioimaging Facility, John Innes Centre, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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11
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Mohanty A, Parida A, Raut RK, Behera RK. Ferritin: A Promising Nanoreactor and Nanocarrier for Bionanotechnology. ACS BIO & MED CHEM AU 2022; 2:258-281. [PMID: 37101573 PMCID: PMC10114856 DOI: 10.1021/acsbiomedchemau.2c00003] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The essence of bionanotechnology lies in the application of nanotechnology/nanomaterials to solve the biological problems. Quantum dots and nanoparticles hold potential biomedical applications, but their inherent problems such as low solubility and associated toxicity due to their interactions at nonspecific target sites is a major concern. The self-assembled, thermostable, ferritin protein nanocages possessing natural iron scavenging ability have emerged as a potential solution to all the above-mentioned problems by acting as nanoreactor and nanocarrier. Ferritins, the cellular iron repositories, are hollow, spherical, symmetric multimeric protein nanocages, which sequester the excess of free Fe(II) and synthesize iron biominerals (Fe2O3·H2O) inside their ∼5-8 nm central cavity. The electrostatics and dynamics of the pore residues not only drives the natural substrate Fe2+ inside ferritin nanocages but also uptakes a set of other metals ions/counterions during in vitro synthesis of nanomaterial. The current review aims to report the recent developments/understanding on ferritin structure (self-assembly, surface/pores electrostatics, metal ion binding sites) and chemistry occurring inside these supramolecular protein cages (protein mediated metal ion uptake and mineralization/nanoparticle formation) along with its surface modification to exploit them for various nanobiotechnological applications. Furthermore, a better understanding of ferritin self-assembly would be highly useful for optimizing the incorporation of nanomaterials via the disassembly/reassembly approach. Several studies have reported the successful engineering of these ferritin protein nanocages in order to utilize them as potential nanoreactor for synthesizing/incorporating nanoparticles and as nanocarrier for delivering imaging agents/drugs at cell specific target sites. Therefore, the combination of nanoscience (nanomaterials) and bioscience (ferritin protein) projects several benefits for various applications ranging from electronics to medicine.
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12
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Mohanty A, Parida A, Subhadarshanee B, Behera N, Subudhi T, Koochana PK, Behera RK. Alteration of Coaxial Heme Ligands Reveals the Role of Heme in Bacterioferritin from Mycobacterium tuberculosis. Inorg Chem 2021; 60:16937-16952. [PMID: 34695354 DOI: 10.1021/acs.inorgchem.1c01554] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The uptake and utilization of iron remains critical for the survival/virulence of the host/pathogens in spite of the limitations (low bioavailability/high toxicity) associated with this nutrient. Both the host and pathogens manage to overcome these problems by utilizing the iron repository protein nanocages, ferritins, which not only sequester and detoxify the free Fe(II) ions but also decrease the iron solubility gap by synthesizing/encapsulating the Fe(III)-oxyhydroxide biomineral in its central hollow nanocavity. Bacterial pathogens including Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, encode a distinct subclass of ferritins called bacterioferritin (BfrA), which binds heme, the versatile redox cofactor, via coaxial, conserved methionine (M52) residues at its subunit-dimer interfaces. However, the exact role of heme in Mtb BfrA remains yet to be established. Therefore, its coaxial ligands were altered via site-directed mutagenesis, which resulted in both heme-bound (M52C; ∼1 heme per cage) and heme-free (M52H and M52L) variants, indicating the importance of M52 residues as preferential heme binding axial ligands in Mtb BfrA. All these variants formed intact nanocages of similar size and iron-loading ability as that of wild-type (WT) Mtb BfrA. However, the as-isolated heme-bound variants (WT and M52C) exhibited enhanced protein stability and reductive iron mobilization as compared to their heme-free analogues (M52H and M52L). Further, increasing the heme content in BfrA variants by reconstitution not only enhanced the cage stability but also facilitated the iron mobilization, suggesting the role of heme. In contrary, heme altered the ferroxidase activity to a lesser extent despite facilitating the accumulation of the reactive intermediates formed during the course of the reaction. The current study suggests that heme in Mtb BfrA enhances the overall stability of the protein and possibly acts as an intrinsic electron relay station to influence the iron mineral dissolution and thus may be associated with Mtb's pathogenicity.
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Affiliation(s)
- Abhinav Mohanty
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Akankshika Parida
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | | | - Narmada Behera
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Tanaya Subudhi
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | | | - Rabindra K Behera
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
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13
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Zhang M, Zhang Y, Han X, Wang J, Yang Y, Ren B, Xia M, Li G, Fang R, He H, Jia Y. Whole genome sequencing of Enterobacter mori, an emerging pathogen of kiwifruit and the potential genetic adaptation to pathogenic lifestyle. AMB Express 2021; 11:129. [PMID: 34533621 PMCID: PMC8448808 DOI: 10.1186/s13568-021-01290-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 09/03/2021] [Indexed: 11/10/2022] Open
Abstract
Members of the Enterobacter genus are gram-negative bacteria, which are used as plant growth-promoting bacteria, and increasingly recovered from economic plants as emerging pathogens. A new Enterobacter mori strain, designated CX01, was isolated as an emerging bacterial pathogen of a recent outbreak of kiwifruit canker-like disease in China. The main symptoms associated with this syndrome are bleeding cankers on the trunk and branch, and brown leaf spots. The genome sequence of E. mori CX01 was determined as a single chromosome of 4,966,908 bp with 4640 predicted open reading frames (ORFs). To better understand the features of the genus and its potential pathogenic mechanisms, five available Enterobacter genomes were compared and a pan-genome of 4870 COGs with 3158 core COGs were revealed. An important feature of the E. mori CX01 genome is that it lacks a type III secretion system often found in pathogenic bacteria, instead it is equipped with type I, II, and VI secretory systems. Besides, the genes encoding putative virulence effectors, two-component systems, nutrient acquisition systems, proteins involved in phytohormone synthesis, which may contribute to the virulence and adaption to the host plant niches are included. The genome sequence of E. mori CX01 has high similarity with that of E. mori LMG 25,706, though the rearrangements occur throughout two genomes. Further pathogenicity assay showed that both strains can either invade kiwifruit or mulberry, indicating they may have similar host range. Comparison with a closely related isolate enabled us to understand its pathogenesis and ecology.
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14
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Wang W, Zhang Y, Zhao G, Wang H. Ferritin with Atypical Ferroxidase Centers Takes B-Channels as the Pathway for Fe 2+ Uptake from Mycoplasma. Inorg Chem 2021; 60:7207-7216. [PMID: 33852289 DOI: 10.1021/acs.inorgchem.1c00265] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Here, we present a 1.9 Å resolution crystal structure of Mycoplasma Penetrans ferritin, which reveals that its ferroxidase center is located on the inner surface of ferritin but not buried within the four-helix of each subunit. Such a ferroxidase center exhibits a lower iron oxidation activity as compared to the reported ferritin. More importantly, we found that Fe2+ enters into the center via the rarely reported B-channels rather than the normal 3- or 4-fold channels. All these findings may provide the structural bases to explore the new iron oxidation mechanism adopted by this special ferritin, which is beneficial for understanding the relationship between the structure and function of ferritin.
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Affiliation(s)
- Wenming Wang
- Institute of Molecular Science, Shanxi University, Taiyuan 030006, China.,Shanxi Key Laboratory of Pharmaceutical Biotechnology, Taiyuan 030006, China
| | - Yao Zhang
- Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
| | - Guanghua Zhao
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Hongfei Wang
- Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
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15
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Koochana PK, Mohanty A, Parida A, Behera N, Behera PM, Dixit A, Behera RK. Flavin-mediated reductive iron mobilization from frog M and Mycobacterial ferritins: impact of their size, charge and reactivities with NADH/O 2. J Biol Inorg Chem 2021; 26:265-281. [PMID: 33598740 DOI: 10.1007/s00775-021-01850-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 01/21/2021] [Indexed: 01/01/2023]
Abstract
In vitro, reductive mobilization of ferritin iron using suitable electron transfer mediators has emerged as a possible mechanism to mimic the iron release process, in vivo. Nature uses flavins as electron relay molecules for important biological oxidation and oxygenation reactions. Therefore, the current work utilizes three flavin analogues: riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which differ in size and charge but have similar redox potentials, to relay electron from nicotinamide adenine dinucleotide (NADH) to ferritin mineral core. Of these, the smallest/neutral analogue, RF, released more iron (~ three fold) in comparison to the larger and negatively charged FMN and FAD. Although iron mobilization got marred during the initial stages under aerobic conditions, but increased with a greater slope at the later stages of the reaction kinetics, which gets inhibited by superoxide dismutase, consistent with the generation of O2∙- in situ. The initial step, i.e., interaction of flavins with NADH played critical role in the iron release process. Overall, the flavin-mediated reductive iron mobilization from ferritins occurred via two competitive pathways, involving the reduced form of flavins either alone (anaerobic condition) or in combination with O2∙- intermediate (aerobic condition). Moreover, faster iron release was observed for ferritins from Mycobacterium tuberculosis than from bullfrog, indicating the importance of protein nanocage and the advantages they provide to the respective organisms. Therefore, these structure-reactivity studies of flavins with NADH/O2 holds significance in ferritin iron release, bioenergetics, O2-based cellular toxicity and may be potentially exploited in the treatment of methemoglobinemia. Smaller sized/neutral flavin analogue, riboflavin (RF) exhibits faster reactivity towards both NADH and O2 generating more amount of O2∙- and releases higher amount of iron from different ferritins, compared to its larger sized/negatively charged derivatives such as FMN and FAD.
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Affiliation(s)
| | - Abhinav Mohanty
- Department of Chemistry, National Institute of Technology, Rourkela, 769008, Odisha, India
| | - Akankshika Parida
- Department of Chemistry, National Institute of Technology, Rourkela, 769008, Odisha, India
| | - Narmada Behera
- Department of Chemistry, National Institute of Technology, Rourkela, 769008, Odisha, India
| | | | - Anshuman Dixit
- Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
| | - Rabindra K Behera
- Department of Chemistry, National Institute of Technology, Rourkela, 769008, Odisha, India.
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16
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Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA. Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H 2O 2 but Slowly with O 2. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:8442-8450. [PMID: 38529354 PMCID: PMC10962548 DOI: 10.1002/ange.202015964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Indexed: 11/09/2022]
Abstract
Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo-EcBfr, pre-loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di-Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di-Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2-unreactive di-Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.
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Affiliation(s)
- Jacob Pullin
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Michael T. Wilson
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Martin Clémancey
- Université Grenoble AlpesCNRS, CEA, IRIGLaboratoire de Chimie et Biologie des Métaux, UMR 524917 rue des Martyrs38000GrenobleFrance
| | - Geneviève Blondin
- Université Grenoble AlpesCNRS, CEA, IRIGLaboratoire de Chimie et Biologie des Métaux, UMR 524917 rue des Martyrs38000GrenobleFrance
| | - Justin M. Bradley
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Geoffrey R. Moore
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Nick E. Le Brun
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Marina Lučić
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
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17
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Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA. Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H 2 O 2 but Slowly with O 2. Angew Chem Int Ed Engl 2021; 60:8361-8369. [PMID: 33482043 PMCID: PMC8049013 DOI: 10.1002/anie.202015964] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Indexed: 01/08/2023]
Abstract
Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo‐EcBfr, pre‐loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di‐Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di‐Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2‐unreactive di‐Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.
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Affiliation(s)
- Jacob Pullin
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Martin Clémancey
- Université Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, 17 rue des Martyrs, 38000, Grenoble, France
| | - Geneviève Blondin
- Université Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, 17 rue des Martyrs, 38000, Grenoble, France
| | - Justin M Bradley
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Geoffrey R Moore
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Nick E Le Brun
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Marina Lučić
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Jonathan A R Worrall
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
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18
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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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19
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Melman A, Bou-Abdallah F. Iron mineralization and core dissociation in mammalian homopolymeric H-ferritin: Current understanding and future perspectives. Biochim Biophys Acta Gen Subj 2020; 1864:129700. [DOI: 10.1016/j.bbagen.2020.129700] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 01/13/2023]
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20
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Yokel RA, Tseng MT, Butterfield DA, Hancock ML, Grulke EA, Unrine JM, Stromberg AJ, Dozier AK, Graham UM. Nanoceria distribution and effects are mouse-strain dependent. Nanotoxicology 2020; 14:827-846. [DOI: 10.1080/17435390.2020.1770887] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Robert A. Yokel
- Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Michael T. Tseng
- Anatomical Sciences & Neurobiology, University of Louisville, Louisville, KY, USA
| | | | - Matthew L. Hancock
- Chemical and Materials Engineering, University of Kentucky, Lexington, KY, USA
| | - Eric A. Grulke
- Chemical and Materials Engineering, University of Kentucky, Lexington, KY, USA
| | - Jason M. Unrine
- Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | | | | | - Uschi M. Graham
- Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
- CDC, NIOSH, Cincinnati, OH, USA
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21
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Graham UM, Dozier AK, Oberdörster G, Yokel RA, Molina R, Brain JD, Pinto JM, Weuve J, Bennett DA. Tissue Specific Fate of Nanomaterials by Advanced Analytical Imaging Techniques - A Review. Chem Res Toxicol 2020; 33:1145-1162. [PMID: 32349469 PMCID: PMC7774012 DOI: 10.1021/acs.chemrestox.0c00072] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A variety of imaging and analytical methods have been developed to study nanoparticles in cells. Each has its benefits, limitations, and varying degrees of expense and difficulties in implementation. High-resolution analytical scanning transmission electron microscopy (HRSTEM) has the unique ability to image local cellular environments adjacent to a nanoparticle at near atomic resolution and apply analytical tools to these environments such as energy dispersive spectroscopy and electron energy loss spectroscopy. These tools can be used to analyze particle location, translocation and potential reformation, ion dispersion, and in vivo synthesis of second-generation nanoparticles. Such analyses can provide in depth understanding of tissue-particle interactions and effects that are caused by the environmental "invader" nanoparticles. Analytical imaging can also distinguish phases that form due to the transformation of "invader" nanoparticles in contrast to those that are triggered by a response mechanism, including the commonly observed iron biomineralization in the form of ferritin nanoparticles. The analyses can distinguish ion species, crystal phases, and valence of parent nanoparticles and reformed or in vivo synthesized phases throughout the tissue. This article will briefly review the plethora of methods that have been developed over the last 20 years with an emphasis on the state-of-the-art techniques used to image and analyze nanoparticles in cells and highlight the sample preparation necessary for biological thin section observation in a HRSTEM. Specific applications that provide visual and chemical mapping of the local cellular environments surrounding parent nanoparticles and second-generation phases are demonstrated, which will help to identify novel nanoparticle-produced adverse effects and their associated mechanisms.
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Affiliation(s)
- Uschi M Graham
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 5555 Ridge Avenue, Cincinnati, Ohio 45213, United States
- Pharmaceutical Sciences, University of Kentucky, 789 South Limestone, Lexington, Kentucky 40506, United States
| | - Alan K Dozier
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 5555 Ridge Avenue, Cincinnati, Ohio 45213, United States
| | - Günter Oberdörster
- School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Robert A Yokel
- Pharmaceutical Sciences, University of Kentucky, 789 South Limestone, Lexington, Kentucky 40506, United States
| | - Ramon Molina
- Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, Massachusetts 02115, United States
| | - Joseph D Brain
- Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, Massachusetts 02115, United States
| | - Jayant M Pinto
- Department of Surgery, The University of Chicago Medicine, 5841 S. Maryland Avenue, Chicago, Illinois 60637, United States
| | - Jennifer Weuve
- School of Public Health, Department of Epidemiology, Boston University, 715 Albany Street, The Talbot Building, T3E & T4E, Boston, Massachusetts 02118, United States
| | - David A Bennett
- Department of Neurological Sciences, Rush University Medical Center, 1725 W. Harrison Street, Suite 1118, Chicago, Illinois 60612, United States
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22
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Bou-Abdallah F, Flint N, Wilkinson T, Salim S, Srivastava AK, Poli M, Arosio P, Melman A. Ferritin exhibits Michaelis-Menten behavior with oxygen but not with iron during iron oxidation and core mineralization. Metallomics 2020; 11:774-783. [PMID: 30720039 DOI: 10.1039/c9mt00001a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The excessively high and inconsistent literature values for Km,Fe and Km,O2 prompted us to examine the iron oxidation kinetics in ferritin, the major iron storage protein in mammals, and to determine whether a traditional Michaelis-Menten enzymatic behavior is obeyed. The kinetics of Fe(ii) oxidation and mineralization catalyzed by three different types of ferritins (recombinant human homopolymer 24H, HuHF, human heteropolymer ∼21H:3L, HL, and horse spleen heteropolymer ∼3.3H:20.7L, HosF) were therefore studied under physiologically relevant O2 concentrations, but also in the presence of excess Fe(ii) and O2 concentrations. The observed iron oxidation kinetics exhibited two distinct phases (phase I and phase II), neither of which obeyed Michaelis-Menten kinetics. While phase I was very rapid and corresponded to the oxidation of approximately 2 Fe(ii) ions per H-subunit, phase II was much slower and varied linearly with the concentration of iron(ii) cations in solution, independent of the size of the iron core. Under low oxygen concentration close to physiological, the iron uptake kinetics revealed a Michaelis-Menten behavior with Km,O2 values in the low μM range (i.e. ∼1-2 μM range). Our experimental Km,O2 values are significantly lower than typical cellular oxygen concentration, indicating that iron oxidation and mineralization in ferritin should not be affected by the oxygenation level of cells, and should proceed even under hypoxic events. A kinetic model is proposed in which the inhibition of the protein's activity is caused by bound iron(iii) cations at the ferroxidase center, with the rate limiting step corresponding to an exchange or a displacement reaction between incoming Fe(ii) cations and bound Fe(iii) cations.
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Affiliation(s)
- Fadi Bou-Abdallah
- Department of Chemistry, State University of New York, Potsdam, NY 13676, USA.
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23
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Parida A, Mohanty A, Kansara BT, Behera RK. Impact of Phosphate on Iron Mineralization and Mobilization in Nonheme Bacterioferritin B from Mycobacterium tuberculosis. Inorg Chem 2019; 59:629-641. [DOI: 10.1021/acs.inorgchem.9b02894] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Akankshika Parida
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Abhinav Mohanty
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Bharat T. Kansara
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Rabindra K. Behera
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
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24
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Stanley SA, Friedman JM. Electromagnetic Regulation of Cell Activity. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a034322. [PMID: 30249601 DOI: 10.1101/cshperspect.a034322] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The ability to observe the effects of rapidly and reversibly regulating cell activity in targeted cell populations has provided numerous physiologic insights. Over the last decade, a wide range of technologies have emerged for regulating cellular activity using optical, chemical, and, more recently, electromagnetic modalities. Electromagnetic fields can freely penetrate cells and tissue and their energy can be absorbed by metal particles. When released, the absorbed energy can in turn gate endogenous or engineered receptors and ion channels to regulate cell activity. In this manner, electromagnetic fields acting on external nanoparticles have been used to exert mechanical forces on cell membranes and organelles to generate heat and interact with thermally activated proteins or to induce receptor aggregation and intracellular signaling. More recently, technologies using genetically encoded nanoparticles composed of the iron storage protein, ferritin, have been used for targeted, temporal control of cell activity in vitro and in vivo. These tools provide a means for noninvasively modulating gene expression, intracellular organelles, such as endosomes, and whole-cell activity both in vitro and in freely moving animals. The use of magnetic fields interacting with external or genetically encoded nanoparticles thus provides a rapid noninvasive means for regulating cell activity.
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Affiliation(s)
- Sarah A Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029.,Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Jeffrey M Friedman
- Laboratory of Molecular Genetics, Rockefeller University, New York, New York 10065.,Howard Hughes Medical Institute, New York, New York 10065
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25
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Mohanty A, Subhadarshanee B, Barman P, Mahapatra C, Aishwarya B, Behera RK. Iron Mineralizing Bacterioferritin A from Mycobacterium tuberculosis Exhibits Unique Catalase-Dps-like Dual Activities. Inorg Chem 2019; 58:4741-4752. [DOI: 10.1021/acs.inorgchem.8b02758] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Abhinav Mohanty
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Biswamaitree Subhadarshanee
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Bhubaneswar 751024, Odisha, India
| | - Pallavi Barman
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Chinmayee Mahapatra
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - B. Aishwarya
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Rabindra K. Behera
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
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26
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Conservation of the structural and functional architecture of encapsulated ferritins in bacteria and archaea. Biochem J 2019; 476:975-989. [PMID: 30837306 DOI: 10.1042/bcj20180922] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/26/2019] [Accepted: 03/04/2019] [Indexed: 11/17/2022]
Abstract
Ferritins are a large family of intracellular proteins that protect the cell from oxidative stress by catalytically converting Fe(II) into less toxic Fe(III) and storing iron minerals within their core. Encapsulated ferritins (EncFtn) are a sub-family of ferritin-like proteins, which are widely distributed in all bacterial and archaeal phyla. The recently characterized Rhodospirillum rubrum EncFtn displays an unusual structure when compared with classical ferritins, with an open decameric structure that is enzymatically active, but unable to store iron. This EncFtn must be associated with an encapsulin nanocage in order to act as an iron store. Given the wide distribution of the EncFtn family in organisms with diverse environmental niches, a question arises as to whether this unusual structure is conserved across the family. Here, we characterize EncFtn proteins from the halophile Haliangium ochraceum and the thermophile Pyrococcus furiosus, which show the conserved annular pentamer of dimers topology. Key structural differences are apparent between the homologues, particularly in the centre of the ring and the secondary metal-binding site, which is not conserved across the homologues. Solution and native mass spectrometry analyses highlight that the stability of the protein quaternary structure differs between EncFtn proteins from different species. The ferroxidase activity of EncFtn proteins was confirmed, and we show that while the quaternary structure around the ferroxidase centre is distinct from classical ferritins, the ferroxidase activity is still inhibited by Zn(II). Our results highlight the common structural organization and activity of EncFtn proteins, despite diverse host environments and contexts within encapsulins.
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Badu-Boateng C, Naftalin RJ. Ascorbate and ferritin interactions: Consequences for iron release in vitro and in vivo and implications for inflammation. Free Radic Biol Med 2019; 133:75-87. [PMID: 30268889 DOI: 10.1016/j.freeradbiomed.2018.09.041] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/25/2018] [Accepted: 09/26/2018] [Indexed: 01/19/2023]
Abstract
This review discusses the chemical mechanisms of ascorbate-dependent reduction and solubilization of ferritin's ferric iron core and subsequent release of ferrous iron. The process is accelerated by low concentrations of Fe(II) that increase ferritin's intrinsic ascorbate oxidase activity, hence increasing the rate of ascorbate radical formation. These increased rates of ascorbate oxidation provide reducing equivalents (electrons) to ferritin's core and speed the core reduction rates with subsequent solubilization and release of Fe(II). Ascorbate-dependent solubilization of ferritin's iron core has consequences relating to the interpretation of 59Fe uptake sourced from 59Fe-lebelled holotransferrin into ferritin. Ascorbate-dependent reduction of the ferritin core iron solubility increases the size of ferritin's iron exchangeable pool and hence the rate and amount of exchange uptake of 59Fe into ferritin, whilst simultaneously increasing net iron release rate from ferritin. This may rationalize the inconsistency that ascorbate apparently stabilizes 59Fe ferritin and retards lysosomal ferritinolysis and whole cell 59Fe release, whilst paradoxically increasing the rate of net iron release from ferritin. This capacity of ascorbate and iron to synergise ferritin iron release has pathological significance, as it lowers the concentration at which ascorbate activates ferritin's iron release to within the physiological range (50-250 μM). These effects have relevance to inflammatory pathology and to the pro-oxidant effects of ascorbate in cancer therapy and cell death by ferroptosis.
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Affiliation(s)
- Charles Badu-Boateng
- Kings, BHF Centre of Research Excellence, School of Cardiovascular Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - Richard J Naftalin
- Kings, BHF Centre of Research Excellence, School of Cardiovascular Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK
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Wijerathne H, Yao H, Wang Y, Lovell S, Battaile KP, Rivera M. Bfd, a New Class of [2Fe-2S] Protein That Functions in Bacterial Iron Homeostasis, Requires a Structural Anion Binding Site. Biochemistry 2018; 57:5533-5543. [PMID: 30183257 DOI: 10.1021/acs.biochem.8b00823] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mobilization of iron from bacterioferritin (BfrB) requires specific interactions with a [2Fe-2S] ferredoxin (Bfd). Blocking the BfrB:Bfd interaction results in irreversible iron accumulation in BfrB and iron deficiency in the cytosol [Eshelman, K., et al. (2017) Metallomics 9, 646-659]. The only known Bfd structure, which was obtained in complex with BfrB (Protein Data Bank entry 4E6K ), indicated a new fold and suggested that the stability of Bfd is aided by an anion binding site consisting of R26, R29, and K46. We investigated the Bfd fold using site-directed mutagenesis, X-ray crystallography, and biochemistry in solution. The X-ray structure, which is nearly identical to that of Bfd in the BfrB:Bfd complex, shows that the [2Fe-2S] cluster preorganizes residues at the BfrB:Bfd interface into a structure complementary to the Bfd binding site on BfrB. Studies in solution showed rapid loss of the [2Fe-2S] cluster at a low ionic strength but higher stability with an increasing ionic strength, thus supporting a structural anion binding site. Structures of the R26E and R26E/K46Y mutants are nearly identical to that of Bfd, except for a new network of hydrogen bonds stabilizing the region encompassing the former anion binding site. The stability of the R26E and R26E/K46Y mutants, which is weakly and completely independent of solution ionic strength, respectively, corroborates that Bfd requires an anion binding site. The mutations, which caused only small changes to the strength of the BfrB:Bfd interaction and mobilization of iron from BfrB, indicate that the anion binding site in Bfd serves primarily a structural role.
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Affiliation(s)
- Harshani Wijerathne
- Department of Chemistry , University of Kansas , Multidisciplinary Research Building, 2030 Becker Drive , Lawrence , Kansas 66047 , United States
| | - Huili Yao
- Department of Chemistry , Louisiana State University , 229A Choppin Hall , Baton Rouge , Louisiana 70803 , United States
| | - Yan Wang
- Department of Chemistry , University of Kansas , Multidisciplinary Research Building, 2030 Becker Drive , Lawrence , Kansas 66047 , United States
| | - Scott Lovell
- Protein Structure Laboratory, Del Shankel Structural Biology Center , University of Kansas , 2034 Becker Drive , Lawrence , Kansas 66047 , United States
| | - Kevin P Battaile
- IMCA-CAT , Hauptman Woodward Medical Research Institute , 9700 South Cass Avenue, Building 435A , Argonne , Illinois 60439 , United States
| | - Mario Rivera
- Department of Chemistry , Louisiana State University , 229A Choppin Hall , Baton Rouge , Louisiana 70803 , United States
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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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30
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Eshelman K, Yao H, Punchi Hewage AND, Deay JJ, Chandler JR, Rivera M. Inhibiting the BfrB:Bfd interaction in Pseudomonas aeruginosa causes irreversible iron accumulation in bacterioferritin and iron deficiency in the bacterial cytosol. Metallomics 2018; 9:646-659. [PMID: 28318006 DOI: 10.1039/c7mt00042a] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Iron is an essential nutrient for bacteria but the reactivity of Fe2+ and the insolubility of Fe3+ present significant challenges to bacterial cells. Iron storage proteins contribute to ameliorating these challenges by oxidizing Fe2+ using O2 and H2O2 as electron acceptors, and by compartmentalizing Fe3+. Two types of iron-storage proteins coexist in bacteria, the ferritins (Ftn) and the heme-containing bacterioferritins (Bfr), but the reasons for their coexistence are largely unknown. P. aeruginosa cells harbor two iron storage proteins (FtnA and BfrB), but nothing is known about their relative contributions to iron homeostasis. Prior studies in vitro have shown that iron mobilization from BfrB requires specific interactions with a ferredoxin (Bfd), but the relevance of the BfrB:Bfd interaction to iron homeostasis in P. aeruginosa is unknown. In this work we explore the repercussions of (i) deleting the bfrB gene, and (ii) perturbing the BfrB:Bfd interaction in P. aeruginosa cells by either deleting the bfd gene or by replacing the wild type bfrB gene with a L68A/E81A double mutant allele in the P. aeruginosa chromosome. The effects of the mutations were evaluated by following the accumulation of iron in BfrB, analyzing levels of free and total intracellular iron, and by characterizing the ensuing iron homeostasis dysregulation phenotypes. The results reveal that P. aeruginosa accumulates iron mainly in BfrB, and that the nutrient does not accumulate in FtnA to detectable levels, even after deletion of the bfrB gene. Perturbing the BfrB:Bfd interaction causes irreversible flow of iron into BfrB, which leads to the accumulation of unusable intracellular iron while severely depleting the levels of free intracellular iron, which drives the cells to an acute iron starvation response despite harboring "normal" levels of total intracellular iron. These results are discussed in the context of a dynamic equilibrium between free cytosolic Fe2+ and Fe3+ compartmentalized in BfrB, which functions as a buffer to oppose rapid changes of free cytosolic iron. Finally, we also show that P. aeruginosa cells utilize iron stored in BfrB for growth in iron-limiting conditions, and that the utilization of BfrB-iron requires a functional BfrB:Bfd interaction.
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Affiliation(s)
- Kate Eshelman
- Department of Chemistry and R. N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Multidisciplinary Research Building, 2030 Becker Dr, Lawrence, KS 66047, USA.
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31
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First biochemical and crystallographic characterization of a fast-performing ferritin from a marine invertebrate. Biochem J 2017; 474:4193-4206. [PMID: 29127253 DOI: 10.1042/bcj20170681] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/06/2017] [Accepted: 11/08/2017] [Indexed: 01/31/2023]
Abstract
Ferritin, a multimeric cage-like enzyme, is integral to iron metabolism across all phyla through the sequestration and storage of iron through efficient ferroxidase activity. While ferritin sequences from ∼900 species have been identified, crystal structures from only 50 species have been reported, the majority from bacterial origin. We recently isolated a secreted ferritin from the marine invertebrate Chaetopterus sp. (parchment tube worm), which resides in muddy coastal seafloors. Here, we present the first ferritin from a marine invertebrate to be crystallized and its biochemical characterization. The initial ferroxidase reaction rate of recombinant Chaetopterus ferritin (ChF) is 8-fold faster than that of recombinant human heavy-chain ferritin (HuHF). To our knowledge, this protein exhibits the fastest catalytic performance ever described for a ferritin variant. In addition to the high-velocity ferroxidase activity, ChF is unique in that it is secreted by Chaetopterus in a bioluminescent mucus. Previous work has linked the availability of Fe2+ to this long-lived bioluminescence, suggesting a potential function for the secreted ferritin. Comparative biochemical analyses indicated that both ChF and HuHF showed similar behavior toward changes in pH, temperature, and salt concentration. Comparison of their crystal structures shows no significant differences in the catalytic sites. Notable differences were found in the residues that line both 3-fold and 4-fold pores, potentially leading to increased flexibility, reduced steric hindrance, or a more efficient pathway for Fe2+ transportation to the ferroxidase site. These suggested residues could contribute to the understanding of iron translocation through the ferritin shell to the ferroxidase site.
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Abstract
The ferric-uptake regulator (Fur) is an Fe2+-responsive transcription factor that coordinates iron homeostasis in many bacteria. Recently, we reported that expression of the Escherichia coli Fur regulon is also impacted by O2 tension. Here, we show that for most of the Fur regulon, Fur binding and transcriptional repression increase under anaerobic conditions, suggesting that Fur is controlled by O2 availability. We found that the intracellular, labile Fe2+ pool was higher under anaerobic conditions compared with aerobic conditions, suggesting that higher Fe2+ availability drove the formation of more Fe2+-Fur and, accordingly, more DNA binding. O2 regulation of Fur activity required the anaerobically induced FeoABC Fe2+ uptake system, linking increased Fur activity to ferrous import under iron-sufficient conditions. The increased activity of Fur under anaerobic conditions led to a decrease in expression of ferric import systems. However, the combined positive regulation of the feoABC operon by ArcA and FNR partially antagonized Fur-mediated repression of feoABC under anaerobic conditions, allowing ferrous transport to increase even though Fur is more active. This design feature promotes a switch from ferric import to the more physiological relevant ferrous iron under anaerobic conditions. Taken together, we propose that the influence of O2 availability on the levels of active Fur adds a previously undescribed layer of regulation in maintaining cellular iron homeostasis.
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33
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Nanoscale iron particles formed from the metalloprotein-like structures prepared using ferrous ions in the presence of sodium glutamate and bovine serum albumin. MONATSHEFTE FUR CHEMIE 2017. [DOI: 10.1007/s00706-017-2030-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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34
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Ebrahimi KH, Bill E, Hagedoorn PL, Hagen WR. Spectroscopic evidence for the role of a site of the di-iron catalytic center of ferritins in tuning the kinetics of Fe(ii) oxidation. MOLECULAR BIOSYSTEMS 2017; 12:3576-3588. [PMID: 27722502 DOI: 10.1039/c6mb00235h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ferritin is a nanocage protein made of 24 subunits. Its major role is to manage intracellular concentrations of free Fe(ii) and Fe(iii) ions, which is pivotal for iron homeostasis across all domains of life. This function of the protein is regulated by a conserved di-iron catalytic center and has been the subject of extensive studies over the past 50 years. Yet, it has not been fully understood how Fe(ii) is oxidized in the di-iron catalytic center and it is not known why eukaryotic and microbial ferritins oxidize Fe(ii) with different kinetics. In an attempt to obtain a new insight into the mechanism of Fe(ii) oxidation and understand the origin of the observed differences in the catalysis of Fe(ii) oxidation among ferritins we studied and compared the mechanism of Fe(ii) oxidation in the eukaryotic human H-type ferritin (HuHF) and the archaeal ferritin from Pyrococcus furiosus (PfFtn). The results show that the spectroscopic characteristics of the intermediate of Fe(ii) oxidation and the Fe(iii)-products are the same in these two ferritins supporting the proposal of unity in the mechanism of Fe(ii) oxidation among eukaryotic and microbial ferritins. Moreover, we observed that a site in the di-iron catalytic center controls the distribution of Fe(ii) among subunits of HuHF and PfFtn differently. This observation explains the reported differences between HuHF and PfFtn in the kinetics of Fe(ii) oxidation and the amount of O2 consumed per Fe(ii) oxidized. These results provide a fresh understanding of the mechanism of Fe(ii) oxidation by ferritins.
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Affiliation(s)
- Kourosh Honarmand Ebrahimi
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion (MPI-CEC), Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Peter-Leon Hagedoorn
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Wilfred R Hagen
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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35
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Badu-Boateng C, Pardalaki S, Wolf C, Lajnef S, Peyrot F, Naftalin RJ. Labile iron potentiates ascorbate-dependent reduction and mobilization of ferritin iron. Free Radic Biol Med 2017; 108:94-109. [PMID: 28336129 DOI: 10.1016/j.freeradbiomed.2017.03.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/29/2017] [Accepted: 03/15/2017] [Indexed: 12/18/2022]
Abstract
Ascorbate mobilizes iron from equine spleen ferritin by two separate processes. Ascorbate alone mobilizes ferritin iron with an apparent Km (ascorbate) ≈1.5mM. Labile iron >2μM, complexed with citrate (10mM), synergises ascorbate-dependent iron mobilization by decreasing the apparent Km (ascorbate) to ≈270μM and raising maximal mobilization rate by ≈5-fold. Catalase reduces the apparent Km(ascorbate) for both ascorbate and ascorbate+iron dependent mobilization by ≈80%. Iron mobilization by ascorbate alone has a higher activation energy (Ea=45.0±5.5kJ/mole) than when mediated by ascorbate with labile iron (10μM) (Ea=13.7±2.2kJ/mole); also mobilization by iron-ascorbate has a three-fold higher pH sensitivity (pH range 6.0-8.0) than with ascorbate alone. Hydrogen peroxide inhibits ascorbate's iron mobilizing action. EPR and autochemiluminescence studies show that ascorbate and labile iron within ferritin enhances radical formation, whereas ascorbate alone produces negligible radicals. These findings suggest that iron catalysed single electron transfer reactions from ascorbate, involving ascorbate or superoxide and possibly ferroxidase tyrosine radicals, accelerate iron mobilization from the ferroxidase centre more than EPR silent, bi-dentate two-electron transfers. These differing modes of electron transference from ascorbate mirror the known mono and bidentate oxidation reactions of dioxygen and hydrogen peroxide with di-ferrous iron at the ferroxidase centre. This study implies that labile iron, at physiological pH, complexed with citrate, synergises iron mobilization from ferritin by ascorbate (50-4000μM). This autocatalytic process can exacerbate oxidative stress in ferritin-containing inflamed tissue.
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Affiliation(s)
- Charles Badu-Boateng
- Cardiovascular Division, British Heart Foundation Centre of Research Excellence and Physiology Department, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - Sofia Pardalaki
- Cardiovascular Division, British Heart Foundation Centre of Research Excellence and Physiology Department, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | | | - Sonia Lajnef
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR CNRS 8601), Université Paris Descartes, 75006 Paris, France
| | - Fabienne Peyrot
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR CNRS 8601), Université Paris Descartes, 75006 Paris, France; ESPE de l'académie de Paris, Université Paris Sorbonne, 75016 Paris, France
| | - Richard J Naftalin
- Cardiovascular Division, British Heart Foundation Centre of Research Excellence and Physiology Department, King's College London, 150 Stamford Street, London SE1 9NH, UK.
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36
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Oxo- and hydroxo-bridged diiron(III) porphyrin dimers: Inorganic and bio-inorganic perspectives and effects of intermacrocyclic interactions. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.02.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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37
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Rivera M. Bacterioferritin: Structure, Dynamics, and Protein-Protein Interactions at Play in Iron Storage and Mobilization. Acc Chem Res 2017; 50:331-340. [PMID: 28177216 PMCID: PMC5358871 DOI: 10.1021/acs.accounts.6b00514] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite its essentiality to life, iron presents significant challenges to cells: the exceedingly low solubility of Fe3+ limits its bioavailability, and the reactivity of Fe2+ toward H2O2 is a source of the toxic hydroxyl radical (HO•). Consequently, cellular levels of free iron are highly regulated to ensure sufficiency while preventing iron-induced toxicity. Relatively little is known about the fate of iron in the bacterial cytosol or how cells balance the need for relatively high cytosolic iron concentrations with the potential toxicity of the nutrient. Iron storage proteins are integral to iron metabolism, and bacteria utilize two types of ferritin-like molecules to store iron, bacterial ferritin (Ftn) and bacterioferritin (Bfr). Ftn and Bfr compartmentalize iron at concentrations far above the solubility of Fe3+ and protect the reducing cell environment from unwanted Fe3+/Fe2+ redox cycling. This Account focuses on our laboratory's efforts to study iron storage proteins in the model bacterium Pseudomonas aeruginosa, an opportunistic pathogen. Prior to our studies, it was thought that P. aeruginosa cells relied on a single Bfr assembled from two distinct subunits coded by the bfrA and bfrB genes. It is now known that, like in most bacteria, two iron storage proteins coexist in P. aeruginosa cells, a bacterial Ftn (FtnA), coded by the ftnA (formerly bfrA) gene and a bacterioferritin (BfrB), coded by the bfrB gene. Studies with BfrB showed that Fe2+ oxidation occurs at ferroxidase centers (FCs), followed by gated translocation of Fe3+ to the interior cavity, a process that is, surprisingly, distinct from that observed with the extensively studied Bfr from Escherichia coli, where the FCs are stable and function only as a catalytic site for O2 reduction. Investigations with BfrB showed that the oxidation of Fe2+ at FCs and the internalization of Fe3+ depend on long-range cooperative motions, extending from 4-fold pores, via B-pores, into FCs. It remains to be seen whether similar studies with E. coli Bfr will reveal distinct cooperative motions contributing to the stability of its FCs. Mobilization of Fe3+ stored in BfrB requires interaction with a ferredoxin (Bfd), which transfers electrons to reduce Fe3+ in the internal cavity of BfrB for subsequent release of Fe2+. The structure of the BfrB/Bfd complex furnished the only known structure of a ferritin molecule in complex with a physiological protein partner. The BfrB/Bfd complex is stabilized by hot-spot residues in both proteins, which interweave into a highly complementary hot region. The hot-spot residues are conserved in the sequences of Bfr and Bfd proteins from a number of bacteria, indicating that the BfrB/Bfd interaction is of widespread significance in bacterial iron metabolism. The BfrB/Bfd structure also furnished the only known structure of a Bfd, which revealed a novel helix-turn-helix fold different from the β-strand and α-helix fold of plant and vertebrate [2Fe-2S]-ferredoxins. Bfds seem to be unique to bacteria; consequently, although mobilization of iron from eukaryotic ferritins may also be facilitated by protein-protein interactions, the nature of the protein that delivers electrons to the ferric core of eukaryotic ferritins remains unknown.
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Affiliation(s)
- Mario Rivera
- Department of Chemistry and Ralph N. Adams
Institute for Bioanalytical Chemistry, University of Kansas, 2030 Becker
Dr., Lawrence, Kansas 66047, United States
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38
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Bradley JM, Svistunenko DA, Moore GR, Le Brun NE. Tyr25, Tyr58 and Trp133 ofEscherichia colibacterioferritin transfer electrons between iron in the central cavity and the ferroxidase centre. Metallomics 2017; 9:1421-1428. [DOI: 10.1039/c7mt00187h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tyr58 and Trp133 play key roles in the formation and decay of the Tyr25 radical species ofE. coliBFR.
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Affiliation(s)
- Justin M. Bradley
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | | | - Geoffrey R. Moore
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
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39
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Graham UM, Jacobs G, Yokel RA, Davis BH, Dozier AK, Birch ME, Tseng MT, Oberdörster G, Elder A, DeLouise L. From Dose to Response: In Vivo Nanoparticle Processing and Potential Toxicity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 947:71-100. [PMID: 28168666 PMCID: PMC6376403 DOI: 10.1007/978-3-319-47754-1_4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adverse human health impacts due to occupational and environmental exposures to manufactured nanoparticles are of concern and pose a potential threat to the continued industrial use and integration of nanomaterials into commercial products. This chapter addresses the inter-relationship between dose and response and will elucidate on how the dynamic chemical and physical transformation and breakdown of the nanoparticles at the cellular and subcellular levels can lead to the in vivo formation of new reaction products. The dose-response relationship is complicated by the continuous physicochemical transformations in the nanoparticles induced by the dynamics of the biological system, where dose, bio-processing, and response are related in a non-linear manner. Nanoscale alterations are monitored using high-resolution imaging combined with in situ elemental analysis and emphasis is placed on the importance of the precision of characterization. The result is an in-depth understanding of the starting particles, the particle transformation in a biological environment, and the physiological response.
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Affiliation(s)
- Uschi M Graham
- University of Kentucky, Lexington, KY, USA.
- CDC/NIOSH DART, Cincinnati, OH, USA.
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40
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Liu X, Lopez PA, Giessen TW, Giles M, Way JC, Silver PA. Engineering Genetically-Encoded Mineralization and Magnetism via Directed Evolution. Sci Rep 2016; 6:38019. [PMID: 27897245 PMCID: PMC5126674 DOI: 10.1038/srep38019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 11/02/2016] [Indexed: 12/12/2022] Open
Abstract
Genetically encoding the synthesis of functional nanomaterials such as magnetic nanoparticles enables sensitive and non-invasive biological sensing and control. Via directed evolution of the natural iron-sequestering ferritin protein, we discovered key mutations that lead to significantly enhanced cellular magnetism, resulting in increased physical attraction of ferritin-expressing cells to magnets and increased contrast for cellular magnetic resonance imaging (MRI). The magnetic mutants further demonstrate increased iron biomineralization measured by a novel fluorescent genetic sensor for intracellular free iron. In addition, we engineered Escherichia coli cells with multiple genomic knockouts to increase cellular accumulation of various metals. Lastly to explore further protein candidates for biomagnetism, we characterized members of the DUF892 family using the iron sensor and magnetic columns, confirming their intracellular iron sequestration that results in increased cellular magnetization.
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Affiliation(s)
- Xueliang Liu
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA.,School of Engineering and Applied Sciences, Harvard University, Pierce Hall, 29 Oxford Street, Cambridge, MA 02138, USA.,Department of Systems Biology, Harvard Medical School, 200 Longwood Ave, Alpert 536, Boston, MA 02115, USA
| | - Paola A Lopez
- Graduate Program in Bioengineering UC Berkeley/UCSF, Department of Bioengineering, 306 Stanley Hall #1762, University of California Berkeley, CA 94720-1762, USA
| | - Tobias W Giessen
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA.,Department of Systems Biology, Harvard Medical School, 200 Longwood Ave, Alpert 536, Boston, MA 02115, USA
| | - Michael Giles
- Harvard College, Harvard University Harvard College, 86 Brattle Street, Cambridge, MA 02138, USA
| | - Jeffrey C Way
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA.,Department of Systems Biology, Harvard Medical School, 200 Longwood Ave, Alpert 536, Boston, MA 02115, USA
| | - Pamela A Silver
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA.,Department of Systems Biology, Harvard Medical School, 200 Longwood Ave, Alpert 536, Boston, MA 02115, USA
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41
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Clark ER, Kurtz DM. Photosensitized H2 generation from "one-pot" and "two-pot" assemblies of a zinc-porphyrin/platinum nanoparticle/protein scaffold. Dalton Trans 2016; 45:630-8. [PMID: 26616549 DOI: 10.1039/c5dt03418c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We report photosensitized H2 generation using a protein scaffold that nucleates formation of platinum nanoparticles (Pt NPs) and contains "built-in" photosensitizers. The photosensitizers, zinc-protoporphyrin IX or zinc-mesoporphyrin IX (ZnP) were incorporated in place of the naturally occurring heme in the 24-subunit iron storage protein bacterioferritin (Bfr) when the ZnPs were added to the E. coli expression medium. We engineered a stable dimeric Bfr variant with two protein subunits sandwiching a ZnP. Ten glycines were also substituted in place of residues surrounding the vinyl side of the porphyrin in order increase access of solvent and/or redox agents. An optimized "one-pot" reaction of this glycine-substituted ZnMP-Bfr dimer with a Pt(iv) salt and borohydride resulted in a ∼50 : 50 mixture of protein in the form of Pt-free glycine-substituted ZnP-Bfr dimers and re-assembled 24-mers surrounding Pt NPs formed in situ. H2 production occurred upon visible light irradiation of this "one-pot" product when combined with triethanolamine as sacrificial electron donor and methyl viologen as electron relay. An analogous "two-pot" system containing mixtures of separately prepared Pt-free glycine-substituted ZnP-Bfr dimer and porphyrin-free Pt NP@Bfr 24-mer also showed robust photosensitized H2 generation. The glycine-substituted-ZnP-Bfr dimer thus served as photosensitizer for catalytic reduction of methyl viologen by triethanolamine, and the reduced methyl viologen was able to transfer electrons across the Bfr 24-mer protein shell to generate H2 at the enclosed Pt NP in a "dark" reaction. Our results demonstrate that Bfr is a readily manipulatable and versatile scaffold for photosensitized redox chemistry.
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Affiliation(s)
- Emily R Clark
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, USA.
| | - Donald M Kurtz
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, USA.
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He D, Hughes S, Vanden-Hehir S, Georgiev A, Altenbach K, Tarrant E, Mackay CL, Waldron KJ, Clarke DJ, Marles-Wright J. Structural characterization of encapsulated ferritin provides insight into iron storage in bacterial nanocompartments. eLife 2016; 5. [PMID: 27529188 PMCID: PMC5012862 DOI: 10.7554/elife.18972] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/14/2016] [Indexed: 12/17/2022] Open
Abstract
Ferritins are ubiquitous proteins that oxidise and store iron within a protein shell to protect cells from oxidative damage. We have characterized the structure and function of a new member of the ferritin superfamily that is sequestered within an encapsulin capsid. We show that this encapsulated ferritin (EncFtn) has two main alpha helices, which assemble in a metal dependent manner to form a ferroxidase center at a dimer interface. EncFtn adopts an open decameric structure that is topologically distinct from other ferritins. While EncFtn acts as a ferroxidase, it cannot mineralize iron. Conversely, the encapsulin shell associates with iron, but is not enzymatically active, and we demonstrate that EncFtn must be housed within the encapsulin for iron storage. This encapsulin nanocompartment is widely distributed in bacteria and archaea and represents a distinct class of iron storage system, where the oxidation and mineralization of iron are distributed between two proteins. DOI:http://dx.doi.org/10.7554/eLife.18972.001 Iron is essential for life as it is a key component of many different enzymes that participate in processes such as energy production and metabolism. However, iron can also be highly toxic to cells because it readily reacts with oxygen. This reaction can damage DNA, proteins and the membranes that surround cells. To balance the cell’s need for iron against its potential damaging effects, organisms have evolved iron storage proteins known as ferritins that form cage-like structures. The ferritins convert iron into a less reactive form that is mineralised and safely stored in the central cavity of the ferritin cage and is available for cells when they need it. Recently, a new family of ferritins known as encapsulated ferritins have been found in some microorganisms. These ferritins are found in bacterial genomes with a gene that codes for a protein cage called an encapsulin. Although the structure of the encapsulin cage is known to look like the shell of a virus, the structure that the encapsulated ferritin itself forms is not known. It is also not clear how encapsulin and the encapsulated ferritin work together to store iron. He et al. have now used the techniques of X-ray crystallography and mass spectrometry to determine the structure of the encapsulated ferritin found in some bacteria. The encapsulated ferritin forms a ring-shaped doughnut in which ten subunits of ferritin are arranged in a ring; this is totally different from the enclosed cages that other ferritins form. Biochemical studies revealed that the encapsulated ferritin is able to convert iron into a less reactive form, but it cannot store iron on its own since it does not form a cage. Thus, the encapsulated ferritin needs to be housed within the encapsulin cage to store iron. Further work is needed to investigate how iron moves into the encapsulin cage to reach the ferritin proteins. Some organisms have both standard ferritin cages and encapsulated ferritins; why this is the case also remains to be discovered. DOI:http://dx.doi.org/10.7554/eLife.18972.002
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Affiliation(s)
- Didi He
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Sam Hughes
- The School of Chemistry, The University of Edinburgh, Edinburgh, United Kingdom
| | - Sally Vanden-Hehir
- The School of Chemistry, The University of Edinburgh, Edinburgh, United Kingdom
| | - Atanas Georgiev
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Kirsten Altenbach
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Emma Tarrant
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcasle upon Tyne, United Kingdom
| | - C Logan Mackay
- The School of Chemistry, The University of Edinburgh, Edinburgh, United Kingdom
| | - Kevin J Waldron
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcasle upon Tyne, United Kingdom
| | - David J Clarke
- The School of Chemistry, The University of Edinburgh, Edinburgh, United Kingdom
| | - Jon Marles-Wright
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,School of Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
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Saenz N, Sánchez M, Gálvez N, Carmona F, Arosio P, Dominguez-Vera JM. Insights on the (Auto)Photocatalysis of Ferritin. Inorg Chem 2016; 55:6047-50. [DOI: 10.1021/acs.inorgchem.6b00547] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Natalie Saenz
- Departamento de Química Inorgánica
and Instituto de Biotecnología, Universidad de Granada, 18071 Granada, Spain
| | - Manu Sánchez
- Departamento de Química Inorgánica
and Instituto de Biotecnología, Universidad de Granada, 18071 Granada, Spain
| | - Natividad Gálvez
- Departamento de Química Inorgánica
and Instituto de Biotecnología, Universidad de Granada, 18071 Granada, Spain
| | - Fernando Carmona
- Department of Molecular
and Translational Medicine, University of Brescia, Viale Europa
11, 25123 Brescia, Italy
| | - Paolo Arosio
- Department of Molecular
and Translational Medicine, University of Brescia, Viale Europa
11, 25123 Brescia, Italy
| | - Jose M. Dominguez-Vera
- Departamento de Química Inorgánica
and Instituto de Biotecnología, Universidad de Granada, 18071 Granada, Spain
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Fischer WW, Hemp J, Valentine JS. How did life survive Earth's great oxygenation? Curr Opin Chem Biol 2016; 31:166-78. [PMID: 27043270 DOI: 10.1016/j.cbpa.2016.03.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/11/2016] [Accepted: 03/15/2016] [Indexed: 12/26/2022]
Abstract
Life on Earth originated and evolved in anoxic environments. Around 2.4 billion-years-ago, ancestors of Cyanobacteria invented oxygenic photosynthesis, producing substantial amounts of O2 as a byproduct of phototrophic water oxidation. The sudden appearance of O2 would have led to significant oxidative stress due to incompatibilities with core cellular biochemical processes. Here we examine this problem through the lens of Cyanobacteria-the first taxa to observe significant fluxes of intracellular dioxygen. These early oxygenic organisms likely adapted to the oxidative stress by co-opting preexisting systems (exaptation) with fortuitous antioxidant properties. Over time more advanced antioxidant systems evolved, allowing Cyanobacteria to adapt to an aerobic lifestyle and become the most important environmental engineers in Earth history.
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Affiliation(s)
- Woodward W Fischer
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States.
| | - James Hemp
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States
| | - Joan Selverstone Valentine
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States; Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, United States.
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45
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Abstract
Ferritins, the main intracellular iron storage proteins, have been studied for over 60 years, mainly focusing on the mammalian ones. This allowed the elucidation of the structure of these proteins and the mechanisms regulating their iron incorporation and mineralization. However, ferritin is present in most, although not all, eukaryotic cells, comprising monocellular and multicellular invertebrates and vertebrates. The aim of this review is to provide an update on the general properties of ferritins that are common to various eukaryotic phyla (except plants), and to give an overview on the structure, function and regulation of ferritins. An update on the animal models that were used to characterize H, L and mitochondrial ferritins is also provided. The data show that ferritin structure is highly conserved among different phyla. It exerts an important cytoprotective function against oxidative damage and plays a role in innate immunity, where it also contributes to prevent parenchymal tissue from the cytotoxicity of pro-inflammatory agonists released by the activation of the immune response activation. Less clear are the properties of the secretory ferritins expressed by insects and molluscs, which may be important for understanding the role played by serum ferritin in mammals.
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46
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Ferritin Assembly in Enterocytes of Drosophila melanogaster. Int J Mol Sci 2016; 17:27. [PMID: 26861293 PMCID: PMC4783870 DOI: 10.3390/ijms17020027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/04/2015] [Accepted: 12/11/2015] [Indexed: 11/30/2022] Open
Abstract
Ferritins are protein nanocages that accumulate inside their cavity thousands of oxidized iron atoms bound to oxygen and phosphates. Both characteristic types of eukaryotic ferritin subunits are present in secreted ferritins from insects, but here dimers between Ferritin 1 Heavy Chain Homolog (Fer1HCH) and Ferritin 2 Light Chain Homolog (Fer2LCH) are further stabilized by disulfide-bridge in the 24-subunit complex. We addressed ferritin assembly and iron loading in vivo using novel transgenic strains of Drosophila melanogaster. We concentrated on the intestine, where the ferritin induction process can be controlled experimentally by dietary iron manipulation. We showed that the expression pattern of Fer2LCH-Gal4 lines recapitulated iron-dependent endogenous expression of the ferritin subunits and used these lines to drive expression from UAS-mCherry-Fer2LCH transgenes. We found that the Gal4-mediated induction of mCherry-Fer2LCH subunits was too slow to effectively introduce them into newly formed ferritin complexes. Endogenous Fer2LCH and Fer1HCH assembled and stored excess dietary iron, instead. In contrast, when flies were genetically manipulated to co-express Fer2LCH and mCherry-Fer2LCH simultaneously, both subunits were incorporated with Fer1HCH in iron-loaded ferritin complexes. Our study provides fresh evidence that, in insects, ferritin assembly and iron loading in vivo are tightly regulated.
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47
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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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48
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Abstract
Iron, a major protein cofactor, is essential for most organisms. Despite the well-known effects of O2 on the oxidation state and solubility of iron, the impact of O2 on cellular iron homeostasis is not well understood. Here we report that in Escherichia coli K-12, the lack of O2 dramatically changes expression of genes controlled by the global regulators of iron homeostasis, the transcription factor Fur and the small RNA RyhB. Using chromatin immunoprecipitation sequencing (ChIP-seq), we found anaerobic conditions promote Fur binding to more locations across the genome. However, by expression profiling, we discovered that the major effect of anaerobiosis was to increase the magnitude of Fur regulation, leading to increased expression of iron storage proteins and decreased expression of most iron uptake pathways and several Mn-binding proteins. This change in the pattern of gene expression also correlated with an unanticipated decrease in Mn in anaerobic cells. Changes in the genes posttranscriptionally regulated by RyhB under aerobic and anaerobic conditions could be attributed to O2-dependent changes in transcription of the target genes: aerobic RyhB targets were enriched in iron-containing proteins associated with aerobic energy metabolism, whereas anaerobic RyhB targets were enriched in iron-containing anaerobic respiratory functions. Overall, these studies showed that anaerobiosis has a larger impact on iron homeostasis than previously anticipated, both by expanding the number of direct Fur target genes and the magnitude of their regulation and by altering the expression of genes predicted to be posttranscriptionally regulated by the small RNA RyhB under iron-limiting conditions. Microbes and host cells engage in an “arms race” for iron, an essential nutrient that is often scarce in the environment. Studies of iron homeostasis have been key to understanding the control of iron acquisition and the downstream pathways that enable microbes to compete for this valuable resource. Here we report that O2 availability affects the gene expression programs of two Escherichia coli master regulators that function in iron homeostasis: the transcription factor Fur and the small RNA regulator RyhB. Fur appeared to be more active under anaerobic conditions, suggesting a change in the set point for iron homeostasis. RyhB preferentially targeted iron-containing proteins of respiration-linked pathways, which are differentially expressed under aerobic and anaerobic conditions. Such findings may be relevant to the success of bacteria within their hosts since zones of reduced O2 may actually reduce bacterial iron demands, making it easier to win the arms race for iron.
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49
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Bradley JM, Svistunenko DA, Lawson TL, Hemmings AM, Moore GR, Le Brun NE. Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin. Angew Chem Int Ed Engl 2015; 54:14763-7. [PMID: 26474305 PMCID: PMC4691338 DOI: 10.1002/anie.201507486] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/17/2015] [Indexed: 12/20/2022]
Abstract
Ferritins are iron storage proteins that overcome the problems of toxicity and poor bioavailability of iron by catalyzing iron oxidation and mineralization through the activity of a diiron ferroxidase site. Unlike in other ferritins, the oxidized di-Fe(3+) site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe(3+) into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe(2+) oxidation in the cavity. Herein, we demonstrate that EcBFR mineralization depends on three aromatic residues near the diiron site, Tyr25, Tyr58, and Trp133, and that a transient radical is formed on Tyr25. The data indicate that the aromatic residues, together with a previously identified inner surface iron site, promote mineralization by ensuring the simultaneous delivery of two electrons, derived from Fe(2+) oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction of O2.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
| | - Dimitri A Svistunenko
- School of Biological Sciences, University of EssexWivenhoe Park, Colchester CO4 3SQ (UK)
| | - Tamara L Lawson
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
- School of Biological SciencesNorwich Research ParkUniversity of East AngliaNorwich NR4 7TJ (UK)
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
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50
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Kwak Y, Schwartz JK, Huang VW, Boice E, Kurtz DM, Solomon EI. CD/MCD/VTVH-MCD Studies of Escherichia coli Bacterioferritin Support a Binuclear Iron Cofactor Site. Biochemistry 2015; 54:7010-8. [PMID: 26551523 DOI: 10.1021/acs.biochem.5b01033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ferritins and bacterioferritins (Bfrs) utilize a binuclear non-heme iron binding site to catalyze oxidation of Fe(II), leading to formation of an iron mineral core within a protein shell. Unlike ferritins, in which the diiron site binds Fe(II) as a substrate, which then autoxidizes and migrates to the mineral core, the diiron site in Bfr has a 2-His/4-carboxylate ligand set that is commonly found in diiron cofactor enzymes. Bfrs could, therefore, utilize the diiron site as a cofactor rather than for substrate iron binding. In this study, we applied circular dichroism (CD), magnetic CD (MCD), and variable-temperature, variable-field MCD (VTVH-MCD) spectroscopies to define the geometric and electronic structures of the biferrous active site in Escherichia coli Bfr. For these studies, we used an engineered M52L variant, which is known to eliminate binding of a heme cofactor but to have very minor effects on either iron oxidation or mineral core formation. We also examined an H46A/D50A/M52L Bfr variant, which additionally disrupts a previously observed mononuclear non-heme iron binding site inside the protein shell. The spectral analyses define a binuclear and an additional mononuclear ferrous site. The biferrous site shows two different five-coordinate centers. After O2 oxidation and re-reduction, only the mononuclear ferrous signal is eliminated. The retention of the biferrous but not the mononuclear ferrous site upon O2 cycling supports a mechanism in which the binuclear site acts as a cofactor for the O2 reaction, while the mononuclear site binds the substrate Fe(II) that, after its oxidation to Fe(III), migrates to the mineral core.
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Affiliation(s)
- Yeonju Kwak
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Jennifer K Schwartz
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Victor W Huang
- Department of Chemistry, University of Texas at San Antonio , One UTSA Circle, San Antonio, Texas 78249, United States
| | - Emily Boice
- Department of Chemistry, University of Texas at San Antonio , One UTSA Circle, San Antonio, Texas 78249, United States
| | - Donald M Kurtz
- Department of Chemistry, University of Texas at San Antonio , One UTSA Circle, San Antonio, Texas 78249, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
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