1
|
Ma L, Zheng JJ, Zhou N, Zhang R, Fang L, Yang Y, Gao X, Chen C, Yan X, Fan K. A natural biogenic nanozyme for scavenging superoxide radicals. Nat Commun 2024; 15:233. [PMID: 38172125 PMCID: PMC10764798 DOI: 10.1038/s41467-023-44463-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 12/14/2023] [Indexed: 01/05/2024] Open
Abstract
Biominerals, the inorganic minerals of organisms, are known mainly for their physical property-related functions in modern living organisms. Our recent discovery of the enzyme-like activities of nanomaterials, coined as nanozyme, inspires the hypothesis that nano-biominerals might function as enzyme-like catalyzers in cells. Here we report that the iron cores of biogenic ferritins act as natural nanozymes to scavenge superoxide radicals. Through analyzing eighteen representative ferritins from three living kingdoms, we find that the iron core of prokaryote ferritin possesses higher superoxide-diminishing activity than that of eukaryotes. Further investigation reveals that the differences in catalytic capability result from the iron/phosphate ratio changes in the iron core, which is mainly determined by the structures of ferritins. The phosphate in the iron core switches the iron core from single crystalline to amorphous iron phosphate-like structure, resulting in decreased affinity to the hydrogen proton of the ferrihydrite-like core that facilitates its reaction with superoxide in a manner different from that of ferric ions. Furthermore, overexpression of ferritins with high superoxide-diminishing activities in E. coli increases the resistance to superoxide, whereas bacterioferritin knockout or human ferritin knock-in diminishes free radical tolerance, highlighting the physiological antioxidant role of this type of nanozymes.
Collapse
Affiliation(s)
- Long Ma
- CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules (CAS), CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100408, China
| | - Jia-Jia Zheng
- Laboratory of Theoretical and Computational Nanoscience, National Center for Nanoscience and Technology of China, Beijing, 100190, China
| | - Ning Zhou
- CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules (CAS), CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Ruofei Zhang
- CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules (CAS), CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Long Fang
- CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules (CAS), CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yili Yang
- China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology, Taizhou, Jiangsu, 225316, China
| | - Xingfa Gao
- Laboratory of Theoretical and Computational Nanoscience, National Center for Nanoscience and Technology of China, Beijing, 100190, China
| | - Chunying Chen
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Xiyun Yan
- CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules (CAS), CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100408, China.
- Nanozyme Medical Center, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450052, China.
- Nanozyme Laboratory in Zhongyuan, Zhengzhou, Henan, 451163, China.
| | - Kelong Fan
- CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules (CAS), CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100408, China.
- Nanozyme Medical Center, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450052, China.
- Nanozyme Laboratory in Zhongyuan, Zhengzhou, Henan, 451163, China.
| |
Collapse
|
2
|
Reutovich AA, Srivastava AK, Smith GL, Foucher A, Yates DM, Stach EA, Papaefthymiou GC, Arosio P, Bou-Abdallah F. Effect of Phosphate and Ferritin Subunit Composition on the Kinetics, Structure, and Reactivity of the Iron Core in Human Homo- and Heteropolymer Ferritins. Biochemistry 2022; 61:2106-2117. [PMID: 36099002 PMCID: PMC9548343 DOI: 10.1021/acs.biochem.2c00354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ferritins are highly conserved supramolecular protein nanostructures that play a key role in iron homeostasis. Thousands of iron atoms can be stored inside their hollow cavity as a hydrated ferric oxyhydroxide mineral. Although phosphate associates with the ferritin iron nanoparticles, the effect of physiological concentrations on the kinetics, structure, and reactivity of ferritin iron cores has not yet been explored. Here, the iron loading and mobilization kinetics were studied in the presence of 1-10 mM phosphate using homopolymer and heteropolymer ferritins having different H to L subunit ratios. In the absence of ferritin, phosphate enhances the rate of ferrous ion oxidation and forms large and soluble polymeric Fe(III)-phosphate species. In the presence of phosphate, Fe(II) oxidation and core formation in ferritin is significantly accelerated with oxidation rates several-fold higher than with phosphate alone. High-angle annular dark-field scanning transmission electron microscopy measurements revealed a strong phosphate effect on both the size and morphology of the iron mineral in H-rich (but not L-rich) ferritins. While iron nanoparticles in L-rich ferritins have spherical shape in the absence and presence of phosphate, iron nanoparticles in H-rich ferritins change from irregular shapes in the absence of phosphate to spherical particles in the presence of phosphate with larger size distribution and smaller particle size. In the presence of phosphate, the kinetics of iron-reductive mobilization from ferritin releases twice as much iron than in its absence. Altogether, our results demonstrate an important role for phosphate, and the ferritin H and L subunit composition toward the kinetics of iron oxidation and removal from ferritin, as well as the structure and reactivity of the iron mineral, and may have an important implication on ferritin iron management in vivo.
Collapse
Affiliation(s)
- Aliaksandra A Reutovich
- Department of Chemistry, State University of New York, Potsdam, New York 13676, United States
| | - Ayush K Srivastava
- Department of Chemistry, State University of New York, Potsdam, New York 13676, United States
| | - Gideon L Smith
- Department of Chemistry, State University of New York, Potsdam, New York 13676, United States
| | - Alexandre Foucher
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Douglas M Yates
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Eric A Stach
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | | | - Paolo Arosio
- Department of Molecular and Translational Medicine, University of Brescia, 25121 Brescia, Italy
| | - Fadi Bou-Abdallah
- Department of Chemistry, State University of New York, Potsdam, New York 13676, United States
| |
Collapse
|
3
|
Morphological difference of Escherichia coli non-heme ferritin iron cores reconstituted in the presence and absence of inorganic phosphate. J Biol Inorg Chem 2022; 27:583-594. [DOI: 10.1007/s00775-022-01952-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/28/2022] [Indexed: 10/15/2022]
|
4
|
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]
|
5
|
Narayanan S, Shahbazian-Yassar R, Shokuhfar T. In Situ Visualization of Ferritin Biomineralization via Graphene Liquid Cell-Transmission Electron Microscopy. ACS Biomater Sci Eng 2020; 6:3208-3216. [PMID: 33463263 DOI: 10.1021/acsbiomaterials.9b01889] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Ferritin biomineralization is essential to regulate the toxic Fe2+ iron ions in the human body. Unravelling the mechanism of biomineralization in ferritin facilitates our understanding of the causes underlying many iron disorder-related diseases. Until now, no report of in situ visualization of ferritin biomineralization events at nanoscale exists due to the requirement for high-resolution imaging of nanometer-sized ferritin proteins in their hydrated states. Herein, for the first time, we show that the biomineralization processes within individual ferritin proteins can be visualized by means of graphene liquid cell-transmission electron microscopy (GLC-TEM). The increase in the ratio of Fe3+/Fe2+ ions over time monitored via electron energy loss spectroscopy (EELS) reveals the change in oxidation state of iron oxide phases with time. This study lays a foundation for future investigations on iron regulation mechanisms in healthy and dysfunctional ferritins.
Collapse
Affiliation(s)
- Surya Narayanan
- Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan Street, Chicago, Illinois 60607, United States
| | - Reza Shahbazian-Yassar
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, Illinois 60607, United States
| | - Tolou Shokuhfar
- Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan Street, Chicago, Illinois 60607, United States
| |
Collapse
|
6
|
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
| |
Collapse
|
7
|
Rahman S, Gagnon GA. Bench-scale evaluation of ferrous iron oxidation kinetics in drinking water: effect of corrosion control and dissolved organic matter. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2014; 49:1-9. [PMID: 24117078 DOI: 10.1080/10934529.2013.823803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Corrosion control strategies are important for many utilities in maintaining water quality from the water treatment plant to the customers' tap. In drinking water with low alkalinity, water quality can become significantly degraded in iron-based pipes if water utilities are not diligent in maintaining proper corrosion control. This article reports on experiments conducted in bicarbonate buffered (5 mg-C/L) synthetic water to determine the effects of corrosion control (pH and phosphate) and dissolved organic matter (DOM) on the rate constants of the Fe(II) oxidation process. A factorial design approach elucidated that pH (P = 0.007, contribution: 42.5%) and phosphate (P = 0.025, contribution: 22.7%) were the statistically significant factors in the Fe(II) oxidation process at a 95% confidence level. The comprehensive study revealed a significant dependency relationship between the Fe(II) oxidation rate constants (k) and phosphate-to- Fe(II) mole ratio. At pH 6.5, the optimum mole ratio was found to be 0.3 to reduce the k values. Conversely, the k values were observed to increase for the phosphate-to- Fe(II) mole ratio > 1. The factorial design approach revealed that chlorine and DOM for the designated dosages did not cause a statistically significant (α = 0.05, P > 0.05)change in rate constants. However, an increment of the chlorine to ferrous iron mole ratio by a factor of ∼ 2.5 resulted in an increase k values by a factor of ∼ 10. This study conclusively demonstrated that the lowest Fe(II) oxidation rate constant was obtained under low pH conditions (pH ≤ 6.5), with chlorine doses less than 2.2 mg/L and with a phosphate-to-Fe(II) mole ratio ≈ 0.3 in the iron water systems.
Collapse
Affiliation(s)
- Safiur Rahman
- a Department of Civil and Resource Engineering , Dalhousie University , Halifax , Nova Scotia , Canada
| | | |
Collapse
|
8
|
Formation and characterization of iron-binding phosphorylated human-like collagen as a potential iron supplement. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:4361-8. [PMID: 23910354 DOI: 10.1016/j.msec.2013.06.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 05/12/2013] [Accepted: 06/19/2013] [Indexed: 11/22/2022]
Abstract
Iron incorporated into food can induce precipitation and unwanted interaction with other components in food. Iron-binding proteins represent a possibility to avoid these problems and other side effects, as the iron is protected. However, there are several technical problems associated with protein-iron complex formation. In this paper, the iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared under physiological conditions through phosphorylated modification. One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. Spectroscopy analysis, differential scanning calorimetry (DSC) and equilibrium dialysis techniques were employed to investigate the characteristics of the Fe-G6P-HLC. The binding sites (nb) and apparent association constant (Kapp) between iron and phosphorylated HLC were measured at nb=23.7 and log Kapp=4.57, respectively. The amount of iron (Fe(2+) sulfate) binding to phosphorylated HLC was found to be a function of pH and phosphate content. In addition, the solubility and thermal stability of HLC were not significantly affected. The results should facilitate the utilization of HLC as a bioactive iron supplement in the food and medical industry and provide an important theoretical evidence for the application of HLC chelates.
Collapse
|
9
|
Boatright WL, Jahan MS. Effect of sequestering intrinsic iron on the electron paramagnetic resonance signals in powdered soy proteins. J Food Sci 2013; 78:C660-6. [PMID: 23551223 DOI: 10.1111/1750-3841.12114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 02/09/2013] [Indexed: 11/29/2022]
Abstract
This investigation examined iron in powdered soy protein products using electron paramagnetic resonance (EPR) spectroscopy, and the effect that selectively binding free iron in isolated soy protein (ISP) had on the occurrence of metastable radicals in powdered soy proteins. EPR analyses of soybean defatted flour, commercial ISP and laboratory ISP samples revealed a peak at g = 4.3 characteristic of high-spin ferric iron in a rhombic-coordinated environment. Commercial ISP samples examined contained higher levels of the rhombic ferric iron than laboratory-prepared ISP samples. During the first 6 wk of storage the primary singlet EPR signal at g = 2.0049 in the commercial ISP samples approximately doubled, and the laboratory prepared samples increased by about 9-fold. The EPR signal was initially about 4-times higher in the freshly prepared commercial samples compared to the corresponding laboratory ISP. Laboratory ISP samples prepared with added deferoxamine to sequester endogenous iron exhibited a large increase in the high-spin ferric iron EPR signal at g = 4.3. ISP treated with deferoxamine also exhibited a multiple-line EPR signal at about g = 2.007, instead of the typical singlet signal at g = 2.0049. The power at which the signal amplitude was half-saturated also changed from about 1 mW in the control ISP to about 20 mW in the deferoxamine treated ISP. The multiple-line EPR spectrum from the ISP treated with deferoxamine increased during storage over a 6-wk period by about 6-fold. The observed changes in EPR line-shape, g-value, and power saturation with the deferoxamine treatment indicate that the primary free-radical signal in powdered ISP samples may be from stabilized tyrosine radicals with spin densities distributed over the aromatic ring.
Collapse
Affiliation(s)
- William L Boatright
- Dept. of Animal and Food Sciences, Univ. of Kentucky, Lexington, KY 40546-0215, USA.
| | | |
Collapse
|
10
|
The ferroxidase center is essential for ferritin iron loading in the presence of phosphate and minimizes side reactions that form Fe(III)-phosphate colloids. Biometals 2011; 25:259-73. [PMID: 22012445 DOI: 10.1007/s10534-011-9500-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Accepted: 10/08/2011] [Indexed: 10/16/2022]
Abstract
Ferritin iron loading was studied in the presence of physiological serum phosphate concentrations (1 mM), elevated serum concentrations (2-5 mM), and intracellular phosphate concentrations (10 mM). Experiments compared iron loading into homopolymers of H and L ferritin with horse spleen ferritin. Prior to studying the reactions with ferritin, a series of control reactions were performed to study the solution chemistry of Fe(2+) and phosphate. In the absence of ferritin, phosphate catalyzed Fe(2+) oxidation and formed soluble polymeric Fe(III)-phosphate complexes. The Fe(III)-phosphate complexes were characterized by electron microscopy and atomic force microscopy, which revealed spherical nanoparticles with diameters of 10-20 nm. The soluble Fe(III)-phosphate complexes also formed as competing reactions during iron loading into ferritin. Elemental analysis on ferritin samples separated from the Fe(III)-phosphate complexes showed that as the phosphate concentration increased, the iron loading into horse ferritin decreased. The composition of the mineral that does form inside horse ferritin has a higher iron/phosphate ratio (~1:1) than ferritin purified from tissue (~10:1). Phosphate significantly inhibited iron loading into L ferritin, due to the lack of the ferroxidase center in this homopolymer. Spectrophotometric assays of iron loading into H ferritin showed identical iron loading curves in the presence of phosphate, indicating that the ferroxidase center of H ferritin efficiently competes with phosphate for the binding and oxidation of Fe(2+). Additional studies demonstrated that H ferritin ferroxidase activity could be used to oxidize Fe(2+) and facilitate the transfer of the Fe(3+) into apo transferrin in the presence of phosphate.
Collapse
|
11
|
Ferritin iron mineralization proceeds by different mechanisms in MOPS and imidazole buffers. J Inorg Biochem 2011; 105:972-7. [DOI: 10.1016/j.jinorgbio.2011.04.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 04/06/2011] [Accepted: 04/06/2011] [Indexed: 11/19/2022]
|
12
|
Zhao G. Phytoferritin and its implications for human health and nutrition. Biochim Biophys Acta Gen Subj 2010; 1800:815-23. [DOI: 10.1016/j.bbagen.2010.01.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 01/15/2010] [Accepted: 01/18/2010] [Indexed: 01/02/2023]
|
13
|
Watt RK, Hilton RJ, Graff DM. Oxido-reduction is not the only mechanism allowing ions to traverse the ferritin protein shell. Biochim Biophys Acta Gen Subj 2010; 1800:745-59. [DOI: 10.1016/j.bbagen.2010.03.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2009] [Revised: 02/20/2010] [Accepted: 03/01/2010] [Indexed: 01/19/2023]
|
14
|
Inhibition and stimulation of formation of the ferroxidase center and the iron core in Pyrococcus furiosus ferritin. J Biol Inorg Chem 2010; 15:1243-53. [PMID: 20582559 PMCID: PMC2988210 DOI: 10.1007/s00775-010-0682-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 06/16/2010] [Indexed: 11/17/2022]
Abstract
Ferritin is a ubiquitous iron-storage protein that has 24 subunits. Each subunit of ferritins that exhibit high Fe(II) oxidation rates has a diiron binding site, the so-called ferroxidase center (FC). The role of the FC appears to be essential for the iron-oxidation catalysis of ferritins. Studies of the iron oxidation by mammalian, bacterial, and archaeal ferritin have indicated different mechanisms are operative for Fe(II) oxidation, and for inhibition of the Fe(II) oxidation by Zn(II). These differences are presumably related to the variations in the amino acid residues of the FC and/or transport channels. We have used a combination of UV–vis spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry to study the inhibiting action of Zn(II) ions on the iron-oxidation process by apoferritin and by ferritin aerobically preloaded with 48 Fe(II) per 24-meric protein, and to study a possible role of phosphate in initial iron mineralization by Pyrococcus furiosus ferritin (PfFtn). Although the empty FC can accommodate two zinc ions, binding of one zinc ion to the FC suffices to essentially abolish iron-oxidation activity. Zn(II) no longer binds to the FC nor does it inhibit iron core formation once the FC is filled with two Fe(III). Phosphate and vanadate facilitate iron oxidation only after formation of a stable FC, whereupon they become an integral part of the core. These results corroborate our previous proposal that the FC in PfFtn is a stable prosthetic group, and they suggest that its formation is essential for iron-oxidation catalysis by the protein.
Collapse
|
15
|
Jacobs JF, Hasan MN, Paik KH, Hagen WR, van Loosdrecht MCM. Development of a bionanotechnological phosphate removal system with thermostable ferritin. Biotechnol Bioeng 2010; 105:918-23. [PMID: 19953676 DOI: 10.1002/bit.22612] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Phosphate removal to ecologically desired levels of <0.01 mg/L is currently dependent on large overdosing of metal salts and production of large amounts of chemical sludge. The present study focuses on the development and performance of a new bionanotechnological phosphate removal system, based on sorption of oxoanions by nanoscale ferric iron particles stabilized within thermostable ferritin from the hyperthermophilic archaeon Pyrococcus furiosus (PfFrt). Laboratory studies show that this thermostable protein nanocage has fast kinetics for phosphate uptake at very low concentrations by catalytic oxidation of iron. In this study we demonstrate essentially complete phosphate removal with a capacity of approximately 11 mg/g PfFrt. Ferritin can easily be immobilized and is amenable to fast and efficient regeneration, making recovery of phosphate possible. The phosphate removal process with PfFrt is, due to its high affinity, able to reach ecologically desired phosphate levels and in addition it is cost competitive with existing techniques.
Collapse
Affiliation(s)
- Johannes F Jacobs
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the Netherlands
| | | | | | | | | |
Collapse
|
16
|
Li C, Qi X, Li M, Zhao G, Hu X. Phosphate facilitates Fe(II) oxidative deposition in pea seed (Pisum sativum) ferritin. Biochimie 2009; 91:1475-81. [PMID: 19735693 DOI: 10.1016/j.biochi.2009.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 08/27/2009] [Indexed: 11/17/2022]
Abstract
The iron core within phytoferritin interior usually contains the high ratio of iron to phosphate, agreeing with the fact that phosphorus and iron are essential nutrient elements for plant growth. It was established that iron oxidation and incorporation into phytoferritin shell occurs in the plastid(s) where the high concentration of phosphate occurs. However, so far, the role of phosphate in iron oxidative deposition in plant ferritin has not been recognized yet. In the present study, Fe(II) oxidative deposition in pea seed ferritin (PSF) was aerobically investigated in the presence of phosphate. Results indicated that phosphate did not affect the stoichiometry of the initial iron(II) oxidation reaction that takes place at ferroxidase centers upon addition of < or =48 Fe(II)/protein to apoferritin, but increased the rate of iron oxidation. At high Fe(II) fluxes into ferritin (>48 Fe(II)/protein), phosphate plays a more significant role in Fe(II) oxidative deposition. For instance, phosphate increased the rate of Fe(II) oxidation about 1-3 fold, and such an increase depends on the concentration of phosphate in the range of 0-2 mM. This effect was attributed to the ability of phosphate to improve the regeneration activity of ferroxidase centers in PSF. In addition, the presence of phosphate caused a significant decrease in the absorption properties of iron core, indicating that phosphate is involved in the formation of the iron core.
Collapse
Affiliation(s)
- Chaorui Li
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | | | | | | | | |
Collapse
|
17
|
Bou-Abdallah F, Carney E, Chasteen ND, Arosio P, Viescas AJ, Papaefthymiou GC. A comparative Mössbauer study of the mineral cores of human H-chain ferritin employing dioxygen and hydrogen peroxide as iron oxidants. Biophys Chem 2007; 130:114-21. [PMID: 17881115 PMCID: PMC2156192 DOI: 10.1016/j.bpc.2007.08.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Accepted: 08/04/2007] [Indexed: 11/20/2022]
Abstract
Ferritins are ubiquitous iron storage and detoxification proteins distributed throughout the plant and animal kingdoms. Mammalian ferritins oxidize and accumulate iron as a ferrihydrite mineral within a shell-like protein cavity. Iron deposition utilizes both O(2) and H(2)O(2) as oxidants for Fe(2+) where oxidation can occur either at protein ferroxidase centers or directly on the surface of the growing mineral core. The present study was undertaken to determine whether the nature of the mineral core formed depends on the protein ferroxidase center versus mineral surface mechanism and on H(2)O(2) versus O(2) as the oxidant. The data reveal that similar cores are produced in all instances, suggesting that the structure of the core is thermodynamically, not kinetically controlled. Cores averaging 500 Fe/protein shell and diameter approximately 2.6 nm were prepared and exhibited superparamagnetic blocking temperatures of 19 and 22 K for the H(2)O(2) and O(2) oxidized samples, respectively. The observed blocking temperatures are consistent with the unexpectedly large effective anisotropy constant K(eff)=312 kJ/m(3) recently reported for ferrihydrite nanoparticles formed in reverse micelles [E.L. Duarte, R. Itri, E. Lima Jr., M.S. Batista, T.S. Berquó and G.F. Goya, Large Magnetic Anisotropy in ferrihydrite nanoparticles synthesized from reverse micelles, Nanotechnology 17 (2006) 5549-5555.]. All ferritin samples exhibited two magnetic phases present in nearly equal amounts and ascribed to iron spins at the surface and in the interior of the nanoparticle. At 4.2 K, the surface spins exhibit hyperfine fields, H(hf), of 436 and 445 kOe for the H(2)O(2) and O(2) samples, respectively. As expected, the spins in the interior of the core exhibit larger H(hf) values, i.e. 478 and 486 kOe for the H(2)O(2) and O(2) samples, respectively. The slightly smaller hyperfine field distribution DH(hf) for both surface (78 kOe vs. 92 kOe) and interior spins (45 kOe vs. 54 kOe) of the O(2) sample compared to the H(2)O(2) samples implies that the former is somewhat more crystalline.
Collapse
Affiliation(s)
- Fadi Bou-Abdallah
- Department of Chemistry, University of New Hampshire, Durham, NH 03824, USA
| | | | | | | | | | | |
Collapse
|
18
|
Electrochemically controlled reconstitution of immobilized ferritins for bioelectronic applications. J Electroanal Chem (Lausanne) 2007. [DOI: 10.1016/j.jelechem.2006.10.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
19
|
Hirsch A, Fischer F, Diederich F. Molekulare Erkennung von Phosphaten in der Strukturbiologie. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200603420] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
20
|
Abstract
Drug-discovery research in the past decade has seen an increased selection of targets with phosphate recognition sites, such as protein kinases and phosphatases, in the past decade. This review attempts, with the help of database-mining tools, to give an overview of the most important principles in molecular recognition of phosphate groups by enzymes. A total of 3003 X-ray crystal structures from the RCSB Protein Data Bank with bound organophosphates has been analyzed individually, in particular for H-bonding interactions between proteins and ligands. The various known binding motifs for phosphate binding are reviewed, and similarities to phosphate complexation by synthetic receptors are highlighted. An analysis of the propensities of amino acids in various classes of phosphate-binding enzymes showed characteristic distributions of amino acids used for phosphate binding. This review demonstrates that structure-based lead development and optimization should carefully address the phosphate-binding-site environment and also proposes new alternatives for filling such sites.
Collapse
Affiliation(s)
- Anna K H Hirsch
- Laboratorium für Organische Chemie, ETH Zürich, Hönggerberg, HCI, 8093 Zürich, Switzerland
| | | | | |
Collapse
|
21
|
Zhang B, Wilson PE, Watt GD. Ferritin-catalyzed consumption of hydrogen peroxide by amine buffers causes the variable Fe2+ to O2 stoichiometry of iron deposition in horse spleen ferritin. J Biol Inorg Chem 2006; 11:1075-86. [PMID: 16896807 DOI: 10.1007/s00775-006-0141-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Accepted: 06/27/2006] [Indexed: 11/24/2022]
Abstract
Ferritin catalyzes the oxidation of Fe2+ by O2 to form a reconstituted Fe3+ oxy-hydroxide mineral core, but extensive studies have shown that the Fe2+ to O2 stoichiometry changes with experimental conditions. At Fe2+ to horse spleen ferritin (HoSF) ratios greater than 200, an upper limit of Fe2+ to O2 of 4 is typically measured, indicating O2 is reduced to 2H2O. In contrast, a lower limit of Fe2+ to O2 of approximately 2 is measured at low Fe2+ to HoSF ratios, implicating H2O2 as a product of Fe2+ deposition. Stoichiometric amounts of H2O2 have not been measured, and H2O2 is proposed to react with an unknown system component. Evidence is presented that identifies this component as amine buffers, including 3-N-morpholinopropanesulfonic acid (MOPS), which is widely used in ferritin studies. In the presence of non-amine buffers, the Fe2+ to O2 stoichiometry was approximately 4.0, but at high concentrations of amine buffers (0.10 M) the Fe2+ to O2 stoichiometry is approximately 2.5 for iron loadings of eight to 30 Fe2+ per HoSF. Decreasing the concentration of amine buffer to zero resulted in an Fe2+ to O2 stoichiometry of approximately 4. Direct evidence for amine buffer modification during Fe2+ deposition was obtained by comparing authentic and modified buffers using mass spectrometry, NMR, and thin layer chromatography. Tris(hydroxymethyl)aminomethane, MOPS, and N-methylmorpholine (a MOPS analog) were all rapidly chemically modified during Fe2+ deposition to form N-oxides. Under identical conditions no modification was detected when amine buffer, H2O2, and O2 were combined with Fe2+ or ferritin separately. Thus, a short-lived ferritin intermediate is required for buffer modification by H2O2. Variation of the Fe2+ to O2 stoichiometry versus the Fe2+ to HoSF ratio and the amine buffer concentration are consistent with buffer modification.
Collapse
Affiliation(s)
- Bo Zhang
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | | | | |
Collapse
|
22
|
Cutler C, Bravo A, Ray AD, Watt RK. Iron loading into ferritin can be stimulated or inhibited by the presence of cations and anions: a specific role for phosphate. J Inorg Biochem 2005; 99:2270-5. [PMID: 16203038 DOI: 10.1016/j.jinorgbio.2005.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 08/12/2005] [Accepted: 08/18/2005] [Indexed: 10/25/2022]
Abstract
Phosphate and other oxo-anions have been shown to stimulate the rate of iron loading into ferritin (J. Polanams, A.D. Ray, R.K. Watt, Inorg. Chem. 44 (2005) 3203-3209). This study was undertaken to determine if accelerated iron loading was a specific effect for phosphate and closely associated oxo-anions or if it was a general anion effect. Controls were also performed with mono-valent cations to determine the effect of these cations on iron loading into ferritin. Cations were shown to slow the rate of iron loading into ferritin. Fluoride and iodide were shown to slow the iron loading process of ferritin. Sulfate was also shown to slow iron loading into ferritin to a more significant extent than the cations or halides tested. The trigonal planar oxo-anions, carbonate and nitrate, did not inhibit or stimulate iron loading. We conclude that the increased rate of iron loading into ferritin is specific to phosphate and other closely associated tetrahedral oxo-anion analogs, that the effect is driven by the insolubility of the iron and anion complex, and that in general, cations and anions slow the rate of iron loading into ferritin.
Collapse
Affiliation(s)
- Christopher Cutler
- The University of New Mexico, Department of Chemistry, 1 University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, United States
| | | | | | | |
Collapse
|
23
|
Polanams J, Ray AD, Watt RK. Nanophase Iron Phosphate, Iron Arsenate, Iron Vanadate, and Iron Molybdate Minerals Synthesized within the Protein Cage of Ferritin. Inorg Chem 2005; 44:3203-9. [PMID: 15847428 DOI: 10.1021/ic048819r] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin.
Collapse
Affiliation(s)
- Jup Polanams
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
| | | | | |
Collapse
|
24
|
Huang HQ, Xiao ZQ, Lin QM, Chen P. Characteristics of Trapping Various Organophosphorus Pesticides with a Ferritin Reactor of Shark Liver (Sphyrna zygaena). Anal Chem 2005; 77:1920-7. [PMID: 15762606 DOI: 10.1021/ac048753h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A reactor is composed of liver ferritin of Sphyrna zygaena (SZLF) and an oscillating bag. A reactive procedure for trapping various organphosphorus pesticides (OPs) with the SZLF reactor in the flowing water is described in detail, showing the maximal trapping numbers of 28 +/-1.0 dichlorovos/SZLF, 42 +/- 1.0 dimethoate/SZLF, and 55 +/- 1.0 methamido-phos/SZLF determined by a improved spectrophotometric method in 12 h. In addition, it is found that the OP numbers trapped by the reactor increase along with the incubation time and its concentration increment in the flowing water (or seawater), respectively. This trapping capacity is considered to depend on the composition of amino acids on the surface of the ferritin shell interior rather than the available volume within the shell. A novel pathway for trapping various OPs with the ferritin is suggested in reference to unstable characteristics of the protein subunits. We claim that the ferritin reactor will be employed to monitor the contamination level of various OPs in the flowing water continuously.
Collapse
Affiliation(s)
- He-Qing Huang
- Department of Biochemistry and Biotechnology, School of Life Sciences, Key Laboratory for Chemical Biology of Fujian Province, China.
| | | | | | | |
Collapse
|
25
|
Huang HQ, Cao TM, Lin QM. Characteristics of trapping copper ions with scrolled ferritin reactor in the flowing seawater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2004; 38:2476-2481. [PMID: 15116856 DOI: 10.1021/es034953j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Native liver ferritin of Dasyatis akajei (DALF), apoDALF, and reconstituted DALF were employed to construct a ferritin reactor, respectively. An apparatus consisting of a mixer, a ferritin reactor, and a magnetic stirrer was constructed to study capacity and feasibility of trapping Cu2+ in the flowing seawater. The experimental results showed that the numbers of trapping Cu2+ with DALF reactor were higher than these with the reactors of apoDALF and reconstituted DALF, respectively, giving the maximal numbers of 98 +/- 5 Cu2+ per molecular DALF in 120 h. We found that the iron layer with a high ratio of phosphate to ion on the surface of the ferritin core played an important role in increasing numbers of trapping Cu2+. In addition, we found two positive relations of dependence of trapping Cu2+ numbers with the reactor on the incubation time and on the Cu2+ concentration in the flowing seawater. Another apparatus consisting of a buoyage, an isolation basket equipped with griddling, and a scrolled ferritin reactor was constructed to study the feasibility of trapping Cu2+ in the sea area. Moreover, the present studies indicated that this apparatus had been used to not only analyze and evaluate the concentration variety of various heavy metal ions such as Cu2+ and Pb2+ diluting by the seawater but also monitor the formation of pollution degree by various small organic molecules during the climax and the neap.
Collapse
Affiliation(s)
- He-Qing Huang
- The Center for Proteomics Research and Department of Biology, School of Life Sciences, The Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, 361005, China.
| | | | | |
Collapse
|
26
|
Aitken-Rogers H, Singleton C, Lewin A, Taylor-Gee A, Moore GR, Le Brun NE. Effect of phosphate on bacterioferritin-catalysed iron(II) oxidation. J Biol Inorg Chem 2003; 9:161-70. [PMID: 14673713 DOI: 10.1007/s00775-003-0504-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2003] [Accepted: 10/22/2003] [Indexed: 10/26/2022]
Abstract
The iron(III) mineral cores of bacterioferritins (BFRs), as isolated, contain a significant component of phosphate, with an iron-to-phosphate ratio approaching 1:1 in some cases. In order to better understand the in vivo core-formation process, the effect of phosphate on in vitro core formation in Escherichia coli BFR was investigated. Iron cores reconstituted in the presence of phosphate were found to have iron-to-phosphate ratios similar to those of native cores, and possessed electron paramagnetic resonance properties characteristic of the phosphate-rich core. Phosphate did not affect the stoichiometry of the initial iron(II) oxidation reaction that takes place at the intrasubunit dinuclear iron-binding sites (phase 2 of core formation), but did increase the rate of oxidation. Phosphate had a more significant effect on subsequent core formation (the phase 3 reaction), increasing the rate up to five-fold at pH 6.5 and 25 degrees C. The dependence of the phase 3 rate on phosphate was complex, being greatest at low phosphate and gradually decreasing until the point of saturation at approximately 2 mM phosphate (for iron(II) concentrations <200 microM). Phosphate caused a significant decrease in the absorption properties of both phase 2 and phase 3 products, and the phosphate dependence of the latter mirrored the observed rate dependence, suggesting that distinct iron(III)-phosphate species are formed at different phosphate concentrations. The effect of phosphate on absorption properties enabled the observation of previously undetected events in the phase 2 to phase 3 transition period.
Collapse
Affiliation(s)
- Helen Aitken-Rogers
- Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
| | | | | | | | | | | |
Collapse
|
27
|
Kong B, Huang HQ, Lin QM, Kim WS, Cai Z, Cao TM, Miao H, Luo DM. Purification, electrophoretic behavior, and kinetics of iron release of liver ferritin of Dasyatis akajei. JOURNAL OF PROTEIN CHEMISTRY 2003; 22:61-70. [PMID: 12739899 DOI: 10.1023/a:1023019911749] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
From the liver of fish Dasyatis akajei, ferritin has been isolated by thermal denaturation and ammonium sulfate fractionation and then further purified by anion exchange chromatography and gel exclusion chromatography. The molecular weight of the liver ferritin of D. akajei (DALF) was measured to be 400 kDa by PAGE. Moreover, SDS-PAGE experimentation indicates that protein shell of DALF consists of the H and L subunits with molecular weight of 18 and 13 kDa, respectively. Using isoelectric focusing with pH ranging from 5.0 to 6.0, the ferritin purified by the PAGE exhibited three bands with different pI values in the gel slab. Diameters of the protein shell and iron core were also investigated by transmission electron microscope and determined to be 10-12 nm and 5-8 nm, respectively. A kinetic study of DALF reveals that the rate of self-regulation of the protein shell rather than the complex surface of the iron core plays an important role in forming a process for iron release with mixed orders.
Collapse
Affiliation(s)
- Bo Kong
- Department of Biology, The Center for Analysis and Testing, The Key Laboratory of MOE for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen 361005, China
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Treffry A, Hirzmann J, Yewdall SJ, Harrison PM. Mechanism of catalysis of Fe(II) oxidation by ferritin H chains. FEBS Lett 2002; 302:108-12. [PMID: 1353023 DOI: 10.1016/0014-5793(92)80417-f] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recombinant H chain ferritins bearing site-directed amino acid substitutions at their ferroxidase centres have been used to study the mechanism of catalysis of Fe(II) oxidation by this protein. UV-difference spectra have been obtained at various times after the aerobic addition of Fe(II) to the recombinants. These indicate that the first product of Fe(II) oxidation by wild type H chain apoferritin is an Fe(III) mu-oxo-bridged dimer. This suggests that fast oxidation is achieved by 2-electron transfer from two Fe(II) to dioxygen. Modelling of Fe(III) dimer binding to human H chain apoferritin shows a solvent-accessible site, which resembles that of ribonucleotide reductase in its ligands. Substitution of these ligands by other amino acids usually prevents dimer formation and leads to greatly reduced Fe(II) oxidation rates.
Collapse
Affiliation(s)
- A Treffry
- Krebs Institute for Biomolecular Research, Department of Molecular Biology, University of Sheffield, UK
| | | | | | | |
Collapse
|
29
|
Rocha ME, Ferreira AM, Bechara EJ. Roles of phosphate and an enoyl radical in ferritin iron mobilization by 5-aminolevulinic acid. Free Radic Biol Med 2000; 29:1272-9. [PMID: 11118817 DOI: 10.1016/s0891-5849(00)00437-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
5-Aminolevulinic acid (ALA), a heme precursor that accumulates in acute intermittent porphyria (AIP) and lead poisoning, undergoes enolization and subsequent iron-catalyzed oxidation at neutral pH. Iron is released from horse spleen ferritin (HoSF) by both ALA-generated O(2)(.-) and enoyl radical (ALA(z.rad)), which amplifies the chain of ALA oxidation (autocatalysis). Iron chelators such as EDTA, ATP, but not citrate, and phosphate accelerate this process and ALA-promoted iron release from HoSF is faster in horse spleen isoferritins containing larger amounts of phosphate in the core. ALA (+0.377 V versus standard hydrogen electrode) is less effective in releasing iron from ferritin than are thioglycollic acid, 6-hydroxydopamine, and N,N,N', N'-tetramethyl-p-phenylenediamine. During electrochemical one electron oxidation of ALA in a nitrogen atmosphere, spin trapping experiments with 3,5-dibromo-4-nitrosobenzenesulfonic acid demonstrated the formation of a spin adduct characterized by a six line signal, indicating a secondary carbon-centered radical and attributed to a resonant ALA&z.rad; radical. Iron is also released in such anaerobic electrochemical oxidations of ALA in the presence of ferritin, suggesting that, in addition to O(2)(*-), ALA&z.rad; can promote iron mobilization from ferritin. Hence, ALA&z.rad; may amplify the metal-catalyzed oxidation of ALA, damaging ALA-accumulating cells and possibly contributing to the symptoms of porphyria.
Collapse
Affiliation(s)
- M E Rocha
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | | | | |
Collapse
|
30
|
Huang HQ, Zhang FZ, Xu LS, Lin QM, Huang JW, Zeng D. Spectroelectrochemical investigation of Azotobacter vinelandii bacterial ferritin. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0302-4598(97)00098-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
31
|
Harrison PM, Arosio P. The ferritins: molecular properties, iron storage function and cellular regulation. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1275:161-203. [PMID: 8695634 DOI: 10.1016/0005-2728(96)00022-9] [Citation(s) in RCA: 1785] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The iron storage protein, ferritin, plays a key role in iron metabolism. Its ability to sequester the element gives ferritin the dual functions of iron detoxification and iron reserve. The importance of these functions is emphasised by ferritin's ubiquitous distribution among living species. Ferritin's three-dimensional structure is highly conserved. All ferritins have 24 protein subunits arranged in 432 symmetry to give a hollow shell with an 80 A diameter cavity capable of storing up to 4500 Fe(III) atoms as an inorganic complex. Subunits are folded as 4-helix bundles each having a fifth short helix at roughly 60 degrees to the bundle axis. Structural features of ferritins from humans, horse, bullfrog and bacteria are described: all have essentially the same architecture in spite of large variations in primary structure (amino acid sequence identities can be as low as 14%) and the presence in some bacterial ferritins of haem groups. Ferritin molecules isolated from vertebrates are composed of two types of subunit (H and L), whereas those from plants and bacteria contain only H-type chains, where 'H-type' is associated with the presence of centres catalysing the oxidation of two Fe(II) atoms. The similarity between the dinuclear iron centres of ferritin H-chains and those of ribonucleotide reductase and other proteins suggests a possible wider evolutionary linkage. A great deal of research effort is now concentrated on two aspects of ferritin: its functional mechanisms and its regulation. These form the major part of the review. Steps in iron storage within ferritin molecules consist of Fe(II) oxidation, Fe(III) migration and the nucleation and growth of the iron core mineral. H-chains are important for Fe(II) oxidation and L-chains assist in core formation. Iron mobilisation, relevant to ferritin's role as iron reserve, is also discussed. Translational regulation of mammalian ferritin synthesis in response to iron and the apparent links between iron and citrate metabolism through a single molecule with dual function are described. The molecule, when binding a [4Fe-4S] cluster, is a functioning (cytoplasmic) aconitase. When cellular iron is low, loss of the [4Fe-4S] cluster allows the molecule to bind to the 5'-untranslated region (5'-UTR) of the ferritin m-RNA and thus to repress translation. In this form it is known as the iron regulatory protein (IRP) and the stem-loop RNA structure to which it binds is the iron regulatory element (IRE). IREs are found in the 3'-UTR of the transferrin receptor and in the 5'-UTR of erythroid aminolaevulinic acid synthase, enabling tight co-ordination between cellular iron uptake and the synthesis of ferritin and haem. Degradation of ferritin could potentially lead to an increase in toxicity due to uncontrolled release of iron. Degradation within membrane-encapsulated "secondary lysosomes' may avoid this problem and this seems to be the origin of another form of storage iron known as haemosiderin. However, in certain pathological states, massive deposits of "haemosiderin' are found which do not arise directly from ferritin breakdown. Understanding the numerous inter-relationships between the various intracellular iron complexes presents a major challenge.
Collapse
Affiliation(s)
- P M Harrison
- Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, UK
| | | |
Collapse
|
32
|
Santambrogio P, Levi S, Cozzi A, Corsi B, Arosio P. Evidence that the specificity of iron incorporation into homopolymers of human ferritin L- and H-chains is conferred by the nucleation and ferroxidase centres. Biochem J 1996; 314 ( Pt 1):139-44. [PMID: 8660274 PMCID: PMC1217016 DOI: 10.1042/bj3140139] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mammalian ferritins are iron-storage proteins made of 24 subunits of two types: the H- and L-chains. L-chains, in contrast with H-chains, lack detectable ferroxidase activity. When ferritins were subjected to iron loading in vitro with increments near the saturation limit of 4000 Fe atoms per molecule, the homopolymers of human H-chains formed insoluble aggregates, caused by non-specific iron hydrolysis, whereas the homopolymers of L-chains remained soluble and incorporated most of the available iron. To analyse the molecular reasons for the difference, Glu-57 and Glu-60, which are conserved and exposed on the cavity of L-chains, were substituted with His, as in H-chains. The double substitution made the L-homopolymers as sensitive as the H-homopolymers to the iron-induced aggregation, whereas the opposite substitution in the H-chain increased homopolymer resistance to the aggregation only marginally. Millimolar concentrations of citrate and phosphate increased iron incorporation in H-homopolymers by reducing non-specific iron hydrolysis, but inhibited that in L-homopolymers by sequestering available iron. The data indicate that the specific iron incorporation into L-homopolymers is mainly due to the iron-nucleation capacity of Glu-57, Glu-60 and other carboxyl groups exposed on the cavity; in contrast, the specificity of iron incorporation into H-homopolymers is related to its ferroxidase activity, which determines rapid Fe(III) accumulation inside the cavity. The finding that ferroxidase centres are essential for the incorporation of iron in the presence of likely candidates of cellular iron transport, such as phosphate and citrate, confirms their importance in ferritin function in vivo.
Collapse
Affiliation(s)
- P Santambrogio
- DIBIT Department of Biological and Technological Research, H. San Raffaele Scientific Institute, Milan, Italy
| | | | | | | | | |
Collapse
|
33
|
|
34
|
Bauminger ER, Treffry A, Hudson AJ, Hechel D, Hodson NW, Andrews SC, Levi S, Nowik I, Arosio P, Guest JR. Iron incorporation into ferritins: evidence for the transfer of monomeric Fe(III) between ferritin molecules and for the formation of an unusual mineral in the ferritin of Escherichia coli. Biochem J 1994; 302 ( Pt 3):813-20. [PMID: 7945207 PMCID: PMC1137303 DOI: 10.1042/bj3020813] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Iron that has been oxidized by H-chain ferritin can be transferred into other ferritin molecules before it is incorporated into mature ferrihydrite iron cores. Iron(III) dimers are formed at the ferroxidase centres of ferritin H chains at an early stage of Fe(II) oxidation. Mössbauer spectroscopic data now show that the iron is transferred as monomeric species arising from dimer dissociation and that it binds to the iron core of the acceptor ferritin. Human H-chain ferritin variants containing altered threefold channels can act as acceptors, as can the ferritin of Escherichia coli (Ec-FTN). A human H-chain ferritin variant with a substituted tyrosine (rHuHF-Y34F) can act as a donor of Fe(III). Since an Fe(III)-tyrosinate (first identified in bullfrog H-chain ferritin) is absent from variant rHuHF-Y34F, the Fe(III) transferred is not derived from this tyrosinate complex. Mössbauer parameters of the small iron cores formed within Ec-FTN are significantly different from those of mammalian ferritins. Analysis of the spectra suggests that they are derived from both ferrihydrite and non-ferrihydrite components. This provides further evidence that the ferritin protein shell can influence the structure of its iron core.
Collapse
Affiliation(s)
- E R Bauminger
- Racah Institute of Physics, Hebrew University, Jerusalem, Israel
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Watt GD, McDonald JW, Chiu CH, Reddy KR. Further characterization of the redox and spectroscopic properties of Azotobacter vinelandii ferritin. J Inorg Biochem 1993; 51:745-58. [PMID: 8245955 DOI: 10.1016/0162-0134(93)85007-u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Bacterial ferritin from Azotobacter vinelandii (AVBF) has many properties in common with and a number of properties distinct from the more thoroughly studied animal ferritins. The most notable differences are the high phosphate content of the mineral core and the presence of heme (12 per AVBF) in AVBF. In both ferritin types, redox reactions are essential to the iron release and deposition function of the ferritins. The heme reduction potential in apo AVBF is pH independent as are both the heme and core reduction potential in holo AVBF. pH measurements confirm the pH independence for heme reduction in apo AVBF; however, they establish the conflicting result that 1.7 +/- 0.2 protons per iron atom are taken up during core reduction. These results are interpreted as a two-step reduction process consisting of a pH independent reduction of heme in holo AVBF followed by a pH dependent reduction of the mineral core. Detailed spectroscopic studies have been undertaken to determine if heme-core interactions are detectable during the redox reactions of AVBF. Optical spectroscopy of the heme groups in apo AVBF demonstrate that all twelve are identical and undergo uniform and rapid reduction. EPR spectroscopy establishes the presence of both low-symmetry, g = 4.3, Fe3+ from the mineral core and low-spin heme with g values of 2.87, 2.32, and 1.46 in holo and identical g values for the low-spin heme in apo AVBF. EPR integration of the heme groups in both apo and holo gave values of 13.2 +/- 1.3 heme spins per AVBF at 4.2, 10, 25, 35, and 45 K. No heme perturbations were detected in holo or apo AVBF by Resonance Raman and circular dichroism spectroscopy. Both reduced and oxidized apo AVBF gave normal fluorescence emission at 330-340 nm when excited at 279 nm. These spectroscopic, redox, and reactivity results provide more detailed properties of AVBF for comparison with other bacterial and animal ferritins.
Collapse
Affiliation(s)
- G D Watt
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602
| | | | | | | |
Collapse
|
36
|
|
37
|
|
38
|
Watt GD, Frankel RB, Jacobs D, Huang H, Papaefthymiou GC. Fe2+ and phosphate interactions in bacterial ferritin from Azotobacter vinelandii. Biochemistry 1992; 31:5672-9. [PMID: 1610815 DOI: 10.1021/bi00139a035] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fe2+ binding to both apo- and holo- bacterial ferritin from Azotobacter vinelandii (AVBF) was measured as a function of pH under carefully controlled anaerobic conditions. Fe2+ binding to apo-AVBF is strongly pH dependent with 25 Fe2+ ions/apo-AVBF binding tightly at pH 5.5 and over 150 Fe2+/apo-AVBF at pH 9.0. Holo-AVBF gave a similar pH-dependent binding profile with over 400 Fe2+/AVBF binding at pH of 9.0. Proton release per Fe2+ bound to either AVBF protein increases with increasing pH until a total of about two protons are released at pH 9.0. These binding results are both qualitatively and quantitatively different from corresponding measurements (Jacobs et al., 1989) on apo- and holo- mammalian ferritin (MF) where less Fe2+ binds in both cases. The high level of Fe2+ binding to holo-AVBF relative to that of mammalian ferritin is a consequence of the higher phosphate content in the core of AVBF. Reduction of AVBF by either dithionite or methyl viologen in the absence of chelating agents demonstrated that phosphate, but not Fe2+, is released from the AVBF core in amounts commensurate with the degree of iron reduction, although even at 100% reduction considerable phosphate remains associated with the reduced mineral core. Fe2+ binding to holo-AVBF made deficient in phosphate was lower than that of native AVBF, while the addition of phosphate to native holo-AVBF increased the Fe2+ binding capacity. These results clearly support the role of phosphate as the site of interaction of Fe2+ with the AVBF mineral core.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- G D Watt
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602
| | | | | | | | | |
Collapse
|
39
|
Xu B, Chasteen N. Iron oxidation chemistry in ferritin. Increasing Fe/O2 stoichiometry during core formation. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54877-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|