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Boncella AE, Sabo ET, Santore RM, Carter J, Whalen J, Hudspeth JD, Morrison CN. The expanding utility of iron-sulfur clusters: Their functional roles in biology, synthetic small molecules, maquettes and artificial proteins, biomimetic materials, and therapeutic strategies. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214229] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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2
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Bonfio C. The curious case of peptide-coordinated iron-sulfur clusters: prebiotic and biomimetic insights. Dalton Trans 2021; 50:801-807. [PMID: 33351009 DOI: 10.1039/d0dt03947k] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iron-sulfur clusters are among the most ancient biological cofactors and are thought to have had an ancient role in mediating the chemical reactions that led to life. Two different, yet complementary approaches, based on bioinorganic chemistry and prebiotic chemistry, have already provided important clues for the formation and activity of biomimetic iron-sulfur analogues in aqueous solution. This frontier article discusses the efforts spent in the last 50 years in the context of peptide-coordinated iron-sulfur clusters, with a particular emphasis on insightful contributions from recent prebiotic chemistry research.
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Affiliation(s)
- Claudia Bonfio
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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3
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Galle LM, Cutsail Iii GE, Nischwitz V, DeBeer S, Span I. Spectroscopic characterization of the Co-substituted C-terminal domain of rubredoxin-2. Biol Chem 2018; 399:787-798. [PMID: 29894292 DOI: 10.1515/hsz-2018-0142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/25/2018] [Indexed: 11/15/2022]
Abstract
Pseudomonas putida rubredoxin-2 (Rxn2) is an essential member of the alkane hydroxylation pathway and transfers electrons from a reductase to the membrane-bound hydroxylase. The regioselective hydroxylation of linear alkanes is a challenging chemical transformation of great interest for the chemical industry. Herein, we report the preparation and spectroscopic characterization of cobalt-substituted P. putida Rxn2 and a truncated version of the protein consisting of the C-terminal domain of the protein. Our spectroscopic data on the Co-substituted C-terminal domain supports a high-spin Co(II) with a distorted tetrahedral coordination environment. Investigation of the two-domain protein Rxn2 provides insights into the metal-binding properties of the N-terminal domain, the role of which is not well understood so far. Circular dichroism, electron paramagnetic resonance and X-ray absorption spectroscopies support an alternative Co-binding site within the N-terminal domain, which appears to not be relevant in nature. We have shown that chemical reconstitution in the presence of Co leads to incorporation of Co(II) into the active site of the C-terminal domain, but not the N-terminal domain of Rxn2 indicating distinct roles for the two rubredoxin domains.
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Affiliation(s)
- Lisa M Galle
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - George E Cutsail Iii
- Max Planck Institute for Chemical Energy Conversion, D-45470 Mülheim an der Ruhr, Germany
| | - Volker Nischwitz
- Central Institute for Engineering, Electronics and Analytics (ZEA-3), Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, D-45470 Mülheim an der Ruhr, Germany
| | - Ingrid Span
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
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4
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Zanello P. The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part I. {Fe(SγCys)4} proteins. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2013.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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5
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Zheng AX, Si J, Tang XY, Miao LL, Yu M, Hou KP, Wang F, Li HX, Lang JP. Reactions of the Cationic Zinc Thiolate Model Complex [Zn(Tab)4](PF6)2 with N-Donor Ligands and Cobalt Dichloride. Inorg Chem 2012; 51:10262-73. [DOI: 10.1021/ic301191n] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ai-Xia Zheng
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of
Organic Chemistry, Chinese Academy of Sciences, Shanghai 210093, People’s Republic of China
| | - Jing Si
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
| | - Xiao-Yan Tang
- Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu 215500,
People’s Republic of China
| | - Li-Li Miao
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
| | - Miao Yu
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
| | - Kai-Peng Hou
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
| | - Fan Wang
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
| | - Hong-Xi Li
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
| | - Jian-Ping Lang
- College of
Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s
Republic of China
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of
Organic Chemistry, Chinese Academy of Sciences, Shanghai 210093, People’s Republic of China
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6
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Maganas D, Milikisyants S, Rijnbeek JMA, Sottini S, Levesanos N, Kyritsis P, Groenen EJJ. A Multifrequency High-Field Electron Paramagnetic Resonance Study of CoIIS4 Coordination. Inorg Chem 2009; 49:595-605. [DOI: 10.1021/ic901911h] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dimitrios Maganas
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, GR-15771 Athens, Greece
| | - Sergey Milikisyants
- Department of Molecular Physics, Huygens Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
| | - Jorrit M. A. Rijnbeek
- Department of Molecular Physics, Huygens Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
| | - Silvia Sottini
- Department of Molecular Physics, Huygens Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
| | - Nikolaos Levesanos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, GR-15771 Athens, Greece
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, GR-15771 Athens, Greece
| | - Edgar J. J. Groenen
- Department of Molecular Physics, Huygens Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
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7
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Reddi AR, Guzman TR, Breece RM, Tierney DL, Gibney BR. Deducing the Energetic Cost of Protein Folding in Zinc Finger Proteins Using Designed Metallopeptides. J Am Chem Soc 2007; 129:12815-27. [PMID: 17902663 DOI: 10.1021/ja073902+] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Zinc finger transcription factors represent the largest single class of metalloproteins in the human genome. Binding of Zn(II) to their canonical Cys4, Cys3His1, or Cys2His2 sites results in metal-induced protein folding events required to achieve their proper structure for biological activity. The thermodynamic contribution of Zn(II) in each of these coordination spheres toward protein folding is poorly understood because of the coupled nature of the metal-ligand and protein-protein interactions. Using an unstructured peptide scaffold, GGG, we have employed fluorimetry, potentiometry, and calorimetry to determine the thermodynamics of Zn(II) binding to the Cys4, Cys3His1, and Cys2His2 ligand sets with minimal interference from protein folding effects. The data show that Zn(II) complexation is entropy driven and modulated by proton release. The formation constants for Zn(II)-GGG with a Cys4, Cys3His1, or Cys2His2 site are 5.6 x 10(16), 1.5 x 10(15), or 2.5 x 10(13) M(-1), respectively. Thus, the Zn(II)-Cys4, Zn(II)-Cys3His1, and Zn(II)-Cys2His2 interactions can provide up to 22.8, 20.7, and 18.3 kcal/mol, respectively, in driving force for protein stabilization, folding, and/or assembly at pH values above the ligand pKa values. While the contributions from the three coordination motifs differ by 4.5 kcal/mol in Zn(II) affinity at pH 9.0, they are equivalent at physiological pH, DeltaG = -16.8 kcal/mol or a Ka = 2.0 x 10(12) M(-1). Calorimetric data show that this is due to proton-based enthalpy-entropy compensation between the favorable entropic term from proton release and the unfavorable enthalpic term due to thiol deprotonation. Since protein folding effects have been minimized in the GGG scaffold, these peptides possess nearly the tightest Zn(II) affinities possible for their coordination motifs. The Zn(II) affinities in each coordination motif are compared between the GGG scaffold and natural zinc finger proteins to determine the free energy required to fold the latter. Several proteins have identical Zn(II) affinities to GGG. That is, little, if any, of their Zn(II) binding energy is required to fold the protein, whereas some have affinities weakened by up to 5.7 kcal/mol; i.e., the Zn(II) binding energy is being used to fold the protein.
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Affiliation(s)
- Amit R Reddi
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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8
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Petros AK, Reddi AR, Kennedy ML, Hyslop AG, Gibney BR. Femtomolar Zn(II) affinity in a peptide-based ligand designed to model thiolate-rich metalloprotein active sites. Inorg Chem 2007; 45:9941-58. [PMID: 17140191 DOI: 10.1021/ic052190q] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metal-ligand interactions are critical components of metalloprotein assembly, folding, stability, electrochemistry, and catalytic function. Research over the past 3 decades on the interaction of metals with peptide and protein ligands has progressed from the characterization of amino acid-metal and polypeptide-metal complexes to the design of folded protein scaffolds containing multiple metal cofactors. De novo metalloprotein design has emerged as a valuable tool both for the modular synthesis of these complex metalloproteins and for revealing the fundamental tenets of metalloprotein structure-function relationships. Our research has focused on using the coordination chemistry of de novo designed metalloproteins to probe the interactions of metal cofactors with protein ligands relevant to biological phenomena. Herein, we present a detailed thermodynamic analysis of Fe(II), Co(II), Zn(II), and[4Fe-4S]2(+/+) binding to IGA, a 16 amino acid peptide ligand containing four cysteine residues, H2N-KLCEGG-CIGCGAC-GGW-CONH2. These studies were conducted to delineate the inherent metal-ion preferences of this unfolded tetrathiolate peptide ligand as well as to evaluate the role of the solution pH on metal-peptide complex speciation. The [4Fe-4S]2(+/+)-IGA complex is both an excellent peptide-based synthetic analogue for natural ferredoxins and is flexible enough to accommodate mononuclear metal-ion binding. Incorporation of a single ferrous ion provides the FeII-IGA complex, a spectroscopic model of a reduced rubredoxin active site that possesses limited stability in aqueous buffers. As expected based on the Irving-Williams series and hard-soft acid-base theory, the Co(II) and Zn(II) complexes of IGA are significantly more stable than the Fe(II) complex. Direct proton competition experiments, coupled with determinations of the conditional dissociation constants over a range of pH values, fully define the thermodynamic stabilities and speciation of each MII-IGA complex. The data demonstrate that FeII-IGA and CoII-IGA have formation constant values of 5.0 x 10(8) and 4.2 x 10(11) M-1, which are highly attenuated at physiological pH values. The data also evince that the formation constant for ZnII-IGA is 8.0 x 10(15) M-1, a value that exceeds the tightest natural protein Zn(II)-binding affinities. The formation constant demonstrates that the metal-ligand binding energy of a ZnII(S-Cys)4 site can stabilize a metalloprotein by -21.6 kcal/mol. Rigorous thermodynamic analyses such as those demonstrated here are critical to current research efforts in metalloprotein design, metal-induced protein folding, and metal-ion trafficking.
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Affiliation(s)
- Amy K Petros
- Department of Chemistry, Columbia University, MC 3121, New York, New York 10027, USA
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9
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Maganas D, Staniland SS, Grigoropoulos A, White F, Parsons S, Robertson N, Kyritsis P, Pneumatikakis G. Structural, spectroscopic and magnetic properties of M[R2P(E)NP(E)R′2]2complexes, M = Co, Mn, E = S, Se and R, R′ = Ph oriPr. Covalency of M–S bonds from experimental data and theoretical calculations. Dalton Trans 2006:2301-15. [PMID: 16688318 DOI: 10.1039/b517938f] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The S/Se-containing bidentate ligands LH of the type R2P(E)NHP(E)R'2, E = S, Se and R, R' = Ph or iPr have been employed to synthesize ML2 (M = Mn, Co) complexes which contain the biologically important MS4 core. Theoretical calculations on the LH and L- forms of the ligands probe the geometric and electronic changes induced by the deprotonation of the LH form, which are correlated with structural data from X-ray crystallography. These results reflect the flexibility of the ligands, which enables them to be rather versatile with respect to the formation of ML2 complexes with varied geometries and MEPNPE metallacycle conformations. A series of old and new ML2 complexes have been synthesized and their structural, spectroscopic and magnetic properties characterized in detail. The nephelauxetic ratio beta of the CoL2 complexes provides evidence of covalent interactions, whereas the EPR properties of the MnL2 complexes are interpreted on the basis of predominant ionic interactions, between the metal center and the ligands, respectively. Additional evidence for the existence of covalent interactions in the CoL2 complexes (R = Ph, iPr, or mixed Ph/iPr), is offered by comparisons between their 31P NMR. The aforementioned notations are supported by extensive theoretical calculations on the ML2 (E = S, R = Me) modelled structures, which probe the covalent and ionic character of the M-S bonds when M = Co or Mn. Wider implications of the findings of the present study on the M-S covalency and its importance in the active sites of various metalloenzymes are also discussed.
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Affiliation(s)
- Dimitrios Maganas
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-157 71 Athens, Greece
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10
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Venkateswara Rao P, Holm RH. Synthetic Analogues of the Active Sites of Iron−Sulfur Proteins. Chem Rev 2004; 104:527-59. [PMID: 14871134 DOI: 10.1021/cr020615+] [Citation(s) in RCA: 412] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- P Venkateswara Rao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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11
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Yang X, Wang XB, Fu YJ, Wang LS. On the Electronic Structure of [1Fe] Fe−S Complexes from Anionic Photoelectron Spectroscopy. J Phys Chem A 2003. [DOI: 10.1021/jp027118h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xin Yang
- Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352, and W.R. Wiley Environmental Molecular Sciences Laboratory, MS K8-88, P.O. Box 999, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Xue-Bin Wang
- Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352, and W.R. Wiley Environmental Molecular Sciences Laboratory, MS K8-88, P.O. Box 999, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - You-Jun Fu
- Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352, and W.R. Wiley Environmental Molecular Sciences Laboratory, MS K8-88, P.O. Box 999, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Lai-Sheng Wang
- Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99352, and W.R. Wiley Environmental Molecular Sciences Laboratory, MS K8-88, P.O. Box 999, Pacific Northwest National Laboratory, Richland, Washington 99352
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12
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Lombardi A, Marasco D, Maglio O, Di Costanzo L, Nastri F, Pavone V. Miniaturized metalloproteins: application to iron-sulfur proteins. Proc Natl Acad Sci U S A 2000; 97:11922-7. [PMID: 11050226 PMCID: PMC17270 DOI: 10.1073/pnas.97.22.11922] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The miniaturization process applied to rubredoxins generated a class of peptide-based metalloprotein models, named METP (miniaturized electron transfer protein). The crystal structure of Desulfovibrio vulgaris rubredoxin was selected as a template for the construction of a tetrahedral (S(gamma)-Cys)(4) iron-binding site. Analysis of the structure showed that a sphere of 17 A in diameter, centered on the metal, circumscribes two unconnected approximately C(2) symmetry related beta-hairpins, each containing the -Cys-(Aaa)(2)-Cys- sequence. These observations provided a starting point for the design of an undecapeptide, which self assembles in the presence of tetrahedrally coordinating metal ions. The METP peptide was synthesized in good yield by standard methodologies. Successful assembly of the METP peptide with Co(II), Zn(II), Fe(II/III), in the expected 2:1 stoichiometry, was proven by UV-visible and circular dichroism spectroscopies. UV-visible analysis of the metal complexes indicated the four Cys ligands tetrahedrally arrange around the metal ion, as designed. Circular dichroism measurements on both the free and metal-bound forms revealed that the metal coordination drives the peptide chain to fold into a turned conformation. NMR characterization of the Zn(II)-METP complex fully supported the structure of the designed model. These results prove that METP reproduces the main features of rubredoxin.
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Affiliation(s)
- A Lombardi
- Department of Chemistry, University of Napoli Federico II, Via Mezzocannone 4, I-80134 Napoli, Italy
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13
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Millar M, Lee JF, O'Sullivan T, Koch SA, Fikar R. Models for the iron-sulfur protein rubredoxin: the use of sterically hindered thiolate ligands to stabilize [Fe(SR)4]1− complexes; some considerations of the structure of the [Fe(S-Cys)4] centers in oxidized rubredoxins. Inorganica Chim Acta 1996. [DOI: 10.1016/0020-1693(96)04924-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Christensen HE, Hammerstad-Pedersen JM, Holm A, Roepstorff P, Ulstrup J, Vorm O, Ostergård S. Synthesis and characterization of a 25-residue rubredoxin(II)-like metalloprotein and its valine-leucine mutant. FEBS Lett 1992; 312:219-22. [PMID: 1426256 DOI: 10.1016/0014-5793(92)80939-e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An iron-sulfur metalloprotein containing the 5-12 and 35-50 residues of Desulfovibrio gigas rubredoxin has been synthesized by Fmoc solid phase peptide synthesis and subsequent peptide folding. A Gly links the two residue chains between Val-5 and Glu-50. Sybyl Tripos structure optimization indicates only minor structural changes of the folded synthetic protein compared to the similar residue positions in the native protein. The UV-VIS spectrum of the reduced synthetic protein is very similar to that of native D. gigas rubredoxin and the molecular mass determined by laser mass spectrometry has the expected value (+/- 2D). No metal is transferred to the gas phase by the laser beam merely by mixing the peptide and iron(II), substantiating that the folding procedure is a necessary pre-requisite for protein formation. The Val-->Leu41 chemical mutant has also been synthesized and behaves in a closely similar fashion.
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Affiliation(s)
- H E Christensen
- Chemistry Department A, Technical University of Denmark, Lyngby
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15
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Overnell J, Good M, Vasàk M. Spectroscopic studies on cadmium (II)- and cobalt(II)-substituted metallothionein from the crab Cancer pagurus. Evidence for one additional low-affinity metal-binding site. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 172:171-7. [PMID: 2831057 DOI: 10.1111/j.1432-1033.1988.tb13869.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The binding of diamagnetic Cd(II) and paramagnetic Co(II) ions to the metal-free form of crab, Cancer pagurus, metallothionein (MT) was studied by various spectroscopic techniques. Both reconstituted and native Cd(II)-MT containing 6 mol Cd(II)/mol protein display electronic absorption, circular dichroism (CD) and magnetic circular dichroism (MCD) spectra which were indistinguishable. The stoichiometric replacement of Cd(II) ions in native Cd(II)6-MT by paramagnetic Co(II) ions enabled the geometry of the metal-binding sites to be probed. The electronic absorption and MCD spectra of Co(II)6-MT revealed features characteristic of distorted tetrahedral tetrathiolate Co(II) coordination for all six metal-binding sites. The stepwise incorporation of Cd(II) and Co(II) ions into this protein was monitored by electronic absorption and CD, and by electronic absorption and EPR spectroscopy, respectively. The results indicate that the metal-thiolate cluster structure is generated when more than four metal ions are bound. Below this titration point separate tetrahedral tetrathiolate complexes exist. This suggests that the cluster formation occurs in a two-step process. Furthermore, the spectroscopic features in both Cd(II)- and Co(II)-metal derivatives above the full metal occupancy of six suggest the existence of one additional metal-binding site. The subsequent loss of one Cd(II) ion from crab Cancer Cd(II)7-MT in the gel filtration studies demonstrate the low metal-binding affinity of the latter site. While the spectroscopic properties indicate an exclusively tetrahedral type of metal-thiolate sulfur coordination for the binding of the first six metal ions, they suggest that the seventh metal ion is coordinated in a different fashion.
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Affiliation(s)
- J Overnell
- Institute of Marine Biochemistry, Aberdeen
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16
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Fluorescence resonance energy transfer studies on the proximity relationship between the intrinsic metal ion and substrate binding sites of Escherichia coli RNA polymerase. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45180-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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17
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Good M, Vasák M. Iron(II)-substituted metallothionein: evidence for the existence of iron-thiolate clusters. Biochemistry 1986; 25:8353-6. [PMID: 3828284 DOI: 10.1021/bi00374a003] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Metallothioneins (MT's) are unique low molecular weight (Mr 6000-7000) metal- and cysteine-rich proteins characterized by two tetrahedral tetrathiolate clusters containing three and four metal ions. Naturally occurring proteins usually contain the diamagnetic metal ions Zn(II) and/or Cd(II). We have now succeeded in substituting these ions by paramagnetic Fe(II). Rabbit liver MT-1 in which all seven metal binding sites were occupied by Fe(II) ions displays absorption features typical of tetrahedral tetrathiolate Fe(II) coordination. This is documented by the presence of a ligand field 5E----5T2 transition in the near-infrared region centered at about 1850 nm (epsilon Fe approximately 100 M-1 cm-1) and a broad charge-transfer absorption in the UV region with a shoulder at 314 nm. A metal-thiolate cluster structure is inferred from the 7 to 20 ratio of metal ions to cysteine residues and from spectral studies in which successive increments of Fe(II) were incorporated into the metal-free protein. Thus, to about 4 equiv, the charge-transfer absorption and magnetic circular dichroism (MCD) features of the complexes formed resemble closely those of reduced rubredoxin from Desulfovibro gigas in which tetrahedral tetrathiolate Fe(II) coordination is documented. However, upon further addition of Fe(II) ions, the charge-transfer absorption bands undergo a progressive red-shift until the full metal occupancy of seven Fe(II) ions per molecule is reached. The bathochromic shift which is also manifested in the MCD spectra can be ascribed to the transformation of some of the terminal thiolate ligands to bridging when the full complement of Fe(II) is bound.(ABSTRACT TRUNCATED AT 250 WORDS)
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18
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Nakata M, Ueyama N, Fuji MA, Nakamura A, Wada K, Matsubara H. Chemical simulation of rubredoxin by iron(II)/tetrapeptide complexes in aqueous triton X-100 micelle solution. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0167-4838(84)90042-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Mo(IV) complexes of cysteine-containing peptides and their interaction with 4Fe ferredoxin model complexes. Inorganica Chim Acta 1983. [DOI: 10.1016/s0020-1693(00)91284-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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20
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Harman B, Sóvágó I. Metal complexes of sulphur-containinng ligands. V. Interactions of cobalt(II) ion with L-cysteine and its derivatives. Inorganica Chim Acta 1983. [DOI: 10.1016/s0020-1693(00)91264-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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22
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Vasák M, Kägi JH, Holmquist B, Vallee BL. Spectral studies of cobalt (II)- and Nickel (II)-metallothionein. Biochemistry 1981; 20:6659-64. [PMID: 6272845 DOI: 10.1021/bi00526a021] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The zinc and cadmium of native rabbit metallothionein-1 were replaced stoichiometrically with either cobalt (II) or nickel (II). The electronic, magnetic circular dichroic (MCD), and electron spin resonance spectra of Co (II)-metallothionein reflect distorted tetrahedral coordination of the cobalt atoms. Both the d-d and charge-transfer spectral regions closely resemble those of simple cobalt-tetrathiolate complexes, implying that their coordination chemistry is analogous. Ni (II) complex ions and Ni (II)-metallothionein similarly exhibit analogous MCD bands in the d-d region. The circular dichroic bands associated with ligand-metal charge-transfer transitions in the non-d-d region of Co (II)- and Ni (II)-metallothionein afford additional evidence for the similarity in tetrahedral microsymmetry of the two metal derivatives. The known ratio of 20 thiolate ligands to 7 metal ions, in conjunction with the spectral evidence for tetrathiolate coordination in metallothionein, represents good evidence that these metal thiolates are organized in clusters.
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Ueyama N, Nakata M, Nakamura A. Oxidized Rubredoxin Models. Iron(III) Complexes of Z–Cys–Ala–Ala–Cys–OMe and Z–Ala–Cys–OMe. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1981. [DOI: 10.1246/bcsj.54.1727] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kostikas A, Petrouleas V, Simopoulos A, Coucouvanis D, Holah D. Mössbauer effect in synthetic analogs of rubredoxin. Chem Phys Lett 1976. [DOI: 10.1016/0009-2614(76)80045-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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