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Olivieri P, Zupok A, Yildiz T, Oltmanns J, Lehmann A, Sokolowska E, Skirycz A, Schünemann V, Leimkühler S. TusA influences Fe-S cluster assembly and iron homeostasis in E. coli by reducing the translation efficiency of Fur. Microbiol Spectr 2024; 12:e0055624. [PMID: 38916309 PMCID: PMC11302051 DOI: 10.1128/spectrum.00556-24] [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: 02/28/2024] [Accepted: 05/20/2024] [Indexed: 06/26/2024] Open
Abstract
All sulfur transfer pathways have generally a l-cysteine desulfurase as an initial sulfur-mobilizing enzyme in common, which serves as a sulfur donor for the biosynthesis of numerous sulfur-containing biomolecules in the cell. In Escherichia coli, the housekeeping l-cysteine desulfurase IscS has several interaction partners, which bind at different sites of the protein. So far, the interaction sites of IscU, Fdx, CyaY, and IscX involved in iron-sulfur (Fe-S) cluster assembly have been mapped, in addition to TusA, which is required for molybdenum cofactor biosynthesis and mnm5s2U34 tRNA modifications, and ThiI, which is involved in thiamine biosynthesis and s4U8 tRNA modifications. Previous studies predicted that the sulfur acceptor proteins bind to IscS one at a time. E. coli TusA has, however, been suggested to be involved in Fe-S cluster assembly, as fewer Fe-S clusters were detected in a ∆tusA mutant. The basis for this reduction in Fe-S cluster content is unknown. In this work, we investigated the role of TusA in iron-sulfur cluster assembly and iron homeostasis. We show that the absence of TusA reduces the translation of fur, thereby leading to pleiotropic cellular effects, which we dissect in detail in this study.IMPORTANCEIron-sulfur clusters are evolutionarily ancient prosthetic groups. The ferric uptake regulator plays a major role in controlling the expression of iron homeostasis genes in bacteria. We show that a ∆tusA mutant is impaired in the assembly of Fe-S clusters and accumulates iron. TusA, therefore, reduces fur mRNA translation leading to pleiotropic cellular effects.
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Affiliation(s)
- Paolo Olivieri
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | - Arkadiuz Zupok
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | - Tugba Yildiz
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | - Jonathan Oltmanns
- Department of Physics, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Angelika Lehmann
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
| | - Ewelina Sokolowska
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Aleksandra Skirycz
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Volker Schünemann
- Department of Physics, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Silke Leimkühler
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam, Potsdam, Germany
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2
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Lindahl PA, Vali SW. Mössbauer-based molecular-level decomposition of the Saccharomyces cerevisiae ironome, and preliminary characterization of isolated nuclei. Metallomics 2022; 14:mfac080. [PMID: 36214417 PMCID: PMC9624242 DOI: 10.1093/mtomcs/mfac080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 09/23/2022] [Indexed: 11/25/2022]
Abstract
One hundred proteins in Saccharomyces cerevisiae are known to contain iron. These proteins are found mainly in mitochondria, cytosol, nuclei, endoplasmic reticula, and vacuoles. Cells also contain non-proteinaceous low-molecular-mass labile iron pools (LFePs). How each molecular iron species interacts on the cellular or systems' level is underdeveloped as doing so would require considering the entire iron content of the cell-the ironome. In this paper, Mössbauer (MB) spectroscopy was used to probe the ironome of yeast. MB spectra of whole cells and isolated organelles were predicted by summing the spectral contribution of each iron-containing species in the cell. Simulations required input from published proteomics and microscopy data, as well as from previous spectroscopic and redox characterization of individual iron-containing proteins. Composite simulations were compared to experimentally determined spectra. Simulated MB spectra of non-proteinaceous iron pools in the cell were assumed to account for major differences between simulated and experimental spectra of whole cells and isolated mitochondria and vacuoles. Nuclei were predicted to contain ∼30 μM iron, mostly in the form of [Fe4S4] clusters. This was experimentally confirmed by isolating nuclei from 57Fe-enriched cells and obtaining the first MB spectra of the organelle. This study provides the first semi-quantitative estimate of all concentrations of iron-containing proteins and non-proteinaceous species in yeast, as well as a novel approach to spectroscopically characterizing LFePs.
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Affiliation(s)
- Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, TX,USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station TX,USA
| | - Shaik Waseem Vali
- Department of Chemistry, Texas A&M University, College Station, TX,USA
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3
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Kim K, Mitra S, Wu G, Berka V, Song J, Yu Y, Poget S, Wang DN, Tsai AL, Zhou M. Six-Transmembrane Epithelial Antigen of Prostate 1 (STEAP1) Has a Single b Heme and Is Capable of Reducing Metal Ion Complexes and Oxygen. Biochemistry 2016; 55:6673-6684. [PMID: 27792302 DOI: 10.1021/acs.biochem.6b00610] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
STEAP1, six-transmembrane epithelial antigen of prostate member 1, is strongly expressed in several types of cancer cells, particularly in prostate cancer, and inhibition of its expression reduces the rate of tumor cell proliferation. However, the physiological function of STEAP1 remains unknown. Here for the first time, we purified a mammalian (rabbit) STEAP1 at a milligram level, permitting its high-quality biochemical and biophysical characterizations. We found that STEAP1 likely assembles as a homotrimer and forms a heterotrimer when co-expressed with STEAP2. Each STEAP1 protomer binds one heme prosthetic group that is mainly low-spin with a pair of histidine axial ligands, with small portions of high-spin and P450-type heme. In its ferrous state, STEAP1 is capable of reducing transition metal ion complexes of Fe3+ and Cu2+. Ferrous STEAP1 also reacts readily with O2 through an outer sphere redox mechanism. Kinetics with all three substrates are biphasic with ∼80 and ∼20% for the fast and slow phases, respectively, in line with its heme heterogeneity. STEAP1 retained a low level of bound FAD during purification, and the binding equilibrium constant, KD, was ∼30 μM. These results highlight STEAP as a novel metal reductase and superoxide synthase and establish a solid basis for further research into understanding how STEAP1 activities may affect cancer progression.
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Affiliation(s)
- Kwangsoo Kim
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, Texas 77030, United States
| | - Sharmistha Mitra
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, Texas 77030, United States
| | - Gang Wu
- Division of Hematology, Department of Internal Medicine, University of Texas-McGovern Medical School , Houston, Texas 77030, United States
| | - Vladimir Berka
- Division of Hematology, Department of Internal Medicine, University of Texas-McGovern Medical School , Houston, Texas 77030, United States
| | - Jinmei Song
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine , New York, New York 10016, United States
| | - Ye Yu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, Texas 77030, United States.,Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine , Shanghai 200025, China
| | - Sebastien Poget
- Department of Chemistry, College of Staten Island , Staten Island, New York 10314, United States
| | - Da-Neng Wang
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine , New York, New York 10016, United States
| | - Ah-Lim Tsai
- Division of Hematology, Department of Internal Medicine, University of Texas-McGovern Medical School , Houston, Texas 77030, United States
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, Texas 77030, United States
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4
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Albers A, Demeshko S, Dechert S, Saouma CT, Mayer JM, Meyer F. Fast proton-coupled electron transfer observed for a high-fidelity structural and functional [2Fe-2S] Rieske model. J Am Chem Soc 2014; 136:3946-54. [PMID: 24506804 PMCID: PMC3985845 DOI: 10.1021/ja412449v] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
Rieske cofactors
have a [2Fe–2S] cluster with unique {His2Cys2} ligation and distinct Fe subsites. The histidine
ligands are functionally relevant, since they allow for coupling of
electron and proton transfer (PCET) during quinol oxidation in respiratory
and photosynthetic ET chains. Here we present the highest fidelity
synthetic analogue for the Rieske [2Fe–2S] cluster reported
so far. This synthetic analogue 5x– emulates the heteroleptic {His2Cys2} ligation of the [2Fe–2S] core, and it also serves
as a functional model that undergoes fast concerted proton and electron
transfer (CPET) upon reaction of the mixed-valent (ferrous/ferric)
protonated 5H2– with TEMPO. The thermodynamics
of the PCET square scheme for 5x– have been determined, and three species (diferric 52–, protonated diferric 5H–, and mixed-valent 53–) have been characterized by X-ray diffraction. pKa values for 5H– and 5H2– differ by about 4 units, and the reduction
potential of 5H– is shifted anodically
by about +230 mV compared to that of 52–. While the N–H bond dissociation free energy of 5H2– (60.2 ± 0.5 kcal mol–1) and the free energy, ΔG°CPET, of its reaction with TEMPO (−6.3 kcal mol–1) are similar to values recently reported for a homoleptic {N2/N2}-coordinated [2Fe–2S] cluster, CPET
is significantly faster for 5H2– with
biomimetic {N2/S2} ligation (k = (9.5 ± 1.2) × 104 M–1 s–1, ΔH‡ = 8.7
± 1.0 kJ mol–1, ΔS‡ = −120 ± 40 J mol–1 K–1, and ΔG‡ = 43.8 ± 0.3 kJ mol–1 at 293 K). These parameters,
and the comparison with homoleptic analogues, provide important information
and new perspectives for the mechanistic understanding of the biological
Rieske cofactor.
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Affiliation(s)
- Antonia Albers
- Institute of Inorganic Chemistry, Georg-August-University Göttingen , Tammannstrasse 4, D-37077 Göttingen, Germany
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Holmes-Hampton GP, Tong WH, Rouault TA. Biochemical and biophysical methods for studying mitochondrial iron metabolism. Methods Enzymol 2014; 547:275-307. [PMID: 25416363 DOI: 10.1016/b978-0-12-801415-8.00015-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Iron is a heavily utilized element in organisms and numerous mechanisms accordingly regulate the trafficking, metabolism, and storage of iron. Despite the high regulation of iron homeostasis, several diseases and mutations can lead to the misregulation and often accumulation of iron in the cytosol or mitochondria of tissues. To understand the genesis of iron overload, it is necessary to employ various techniques to quantify iron in organisms and mitochondria. This chapter discusses techniques for determining the total iron content of tissue samples, ranging from colorimetric determination of iron concentrations, atomic absorption spectroscopy, inductively coupled plasma-optical emission spectroscopy, and inductively coupled plasma-mass spectrometry. In addition, we discuss in situ techniques for analyzing iron including electron microscopic nonheme iron histochemistry, electron energy loss spectroscopy, synchrotron X-ray fluorescence imaging, and confocal Raman microscopy. Finally, we discuss biophysical methods for studying iron in isolated mitochondria, including ultraviolet-visible, electron paramagnetic resonance, X-ray absorbance, and Mössbauer spectroscopies. This chapter should aid researchers to select and interpret mitochondrial iron quantifications.
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Affiliation(s)
- Gregory P Holmes-Hampton
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA
| | - Wing-Hang Tong
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA
| | - Tracey A Rouault
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA.
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6
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Wu G, Liu W, Berka V, Tsai AL. The selectivity of Vibrio cholerae H-NOX for gaseous ligands follows the "sliding scale rule" hypothesis. Ligand interactions with both ferrous and ferric Vc H-NOX. Biochemistry 2013; 52:9432-46. [PMID: 24351060 DOI: 10.1021/bi401408x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 μM, respectively, but weakly to O2. When positioned on a "sliding scale" plot [Tsai, A.-l., et al. (2012) Biochemistry 51, 172-186], the line connecting log K(D)(NO) and log K(D)(CO) of Vc H-NOX can almost be superimposed with that of Ns H-NOX. Therefore, the measured affinities and kinetic parameters of gaseous ligands to Vc H-NOX provide more evidence to validate the "sliding scale rule" hypothesis. Like sGC, Vc H-NOX binds NO in multiple steps, forming first a six-coordinate heme-NO complex at a rate of 1.1 × 10(9) M(-1) s(-1), and then converts to a five-coordinate heme-NO complex at a rate that is also dependent on NO concentration. Although the formation of oxyferrous Vc H-NOX cannot be detected at a normal atmospheric oxygen level, ferrous Vc H-NOX is oxidized to the ferric form at a rate of 0.06 s(-1) when mixed with O2. Ferric Vc H-NOX exists as a mixture of high- and low-spin states and is influenced by binding to different ligands. Characterization of both ferric and ferrous Vc H-NOX and their complexes with various ligands lays the foundation for understanding the possible dual roles in gas and redox sensing of Vc H-NOX.
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Affiliation(s)
- Gang Wu
- Division of Hematology, Department of Internal Medicine, The University of Texas-Medical School at Houston , 6431 Fannin Street, Houston, Texas 77030, United States
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8
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Characterization of two cytochrome b 6 proteins from the cyanobacterium Gloeobacter violaceus PCC 7421. J Bioenerg Biomembr 2010; 42:517-26. [DOI: 10.1007/s10863-010-9279-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 01/22/2010] [Indexed: 11/29/2022]
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9
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Zoppellaro G, Bren KL, Ensign AA, Harbitz E, Kaur R, Hersleth HP, Ryde U, Hederstedt L, Andersson KK. Review: studies of ferric heme proteins with highly anisotropic/highly axial low spin (S = 1/2) electron paramagnetic resonance signals with bis-histidine and histidine-methionine axial iron coordination. Biopolymers 2009; 91:1064-82. [PMID: 19536822 PMCID: PMC2852197 DOI: 10.1002/bip.21267] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Six-coordinated heme groups are involved in a large variety of electron transfer reactions because of their ability to exist in both the ferrous (Fe(2+)) and ferric (Fe(3+)) state without any large differences in structure. Our studies on hemes coordinated by two histidines (bis-His) and hemes coordinated by histidine and methionine (His-Met) will be reviewed. In both of these coordination environments, the heme core can exhibit ferric low spin (electron paramagnetic resonance EPR) signals with large g(max) values (also called Type I, highly anisotropic low spin, or highly axial low spin, HALS species) as well as rhombic EPR (Type II) signals. In bis-His coordinated hemes rhombic and HALS envelopes are related to the orientation of the His groups with respect to each other such that (i) parallel His planes results in a rhombic signal and (ii) perpendicular His planes results in a HALS signal. Correlation between the structure of the heme and its ligands for heme with His-Met axial ligation and ligand-field parameters, as derived from a large series of cytochrome c variants, show, however, that for such a combination of axial ligands there is no clear-cut difference between the large g(max) and the "small g-anisotropy" cases as a result of the relative Met-His arrangements. Nonetheless, a new linear correlation links the average shift delta of the heme methyl groups with the g(max) values.
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Affiliation(s)
- Giorgio Zoppellaro
- Department of Molecular Biosciences, University of Oslo, PO Box 1041 Blindern, Oslo NO–0316, Norway
| | - Kara L. Bren
- Department of Chemistry, University of Rochester, Rochester, New York 146270216, USA
| | - Amy A. Ensign
- Department of Chemistry, University of Rochester, Rochester, New York 146270216, USA
| | - Espen Harbitz
- Department of Molecular Biosciences, University of Oslo, PO Box 1041 Blindern, Oslo NO–0316, Norway
| | - Ravinder Kaur
- Department of Chemistry, University of Rochester, Rochester, New York 146270216, USA
| | - Hans-Petter Hersleth
- Department of Molecular Biosciences, University of Oslo, PO Box 1041 Blindern, Oslo NO–0316, Norway
| | - Ulf Ryde
- Department Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, SE–221 00 Lund, Sweden
| | - Lars Hederstedt
- Department of Cell & Organism Biology, Lund University, Sölvegatan 35, SE–22362 Lund, Sweden
| | - K. Kristoffer Andersson
- Department of Molecular Biosciences, University of Oslo, PO Box 1041 Blindern, Oslo NO–0316, Norway
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Milikisyants S, Scarpelli F, Finiguerra MG, Ubbink M, Huber M. A pulsed EPR method to determine distances between paramagnetic centers with strong spectral anisotropy and radicals: the dead-time free RIDME sequence. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 201:48-56. [PMID: 19758831 DOI: 10.1016/j.jmr.2009.08.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 07/15/2009] [Accepted: 08/07/2009] [Indexed: 05/09/2023]
Abstract
Methods to determine distances between paramagnetic metal centers and radicals are scarce. This is unfortunate because paramagnetic metal centers are frequent in biological systems and so far have not been employed much as distance markers. Successful pulse sequences that directly target the dipolar interactions cannot be applied to paramagnetic metal centers with fast relaxation rates and large g-anisotropy, if no echos can be detected and the excitation bandwidth is not sufficient to cover a sufficiently large part of the spectrum. The RIDME method Kulik et al. (2002) [20] circumvents this problem by making use of the T(1)-induced spin-flip of the transition-metal ion. Designed to measure distance between such a fast relaxing metal center and a radical, it suffers from a dead time problem. We show that this is severe because the anisotropy of the metal center broadens the dipolar curves, which therefore, only can be analyzed if the full curve is known. Here, we introduce five-pulse RIDME (5p-RIDME) that is intrinsically dead-time free. Proper functioning of the sequence is demonstrated on a nitroxide biradical. The distance between a low-spin Fe(III) center and a spin label in spin-labeled cytochrome f shows the complete dipolar trace of a transition-metal ion center and a spin label, yielding the distance expected from the structure.
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Affiliation(s)
- Sergey Milikisyants
- Department of Molecular Physics, Huygens Laboratory, Leiden University, 2300 RA Leiden, The Netherlands
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11
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Bis-histidine-coordinated hemes in four-helix bundles: how the geometry of the bundle controls the axial imidazole plane orientations in transmembrane cytochromes of mitochondrial complexes II and III and related proteins. J Biol Inorg Chem 2008; 13:481-98. [PMID: 18418633 DOI: 10.1007/s00775-008-0372-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Accepted: 03/27/2008] [Indexed: 10/22/2022]
Abstract
Early investigation of the electron paramagnetic resonance spectra of bis-histidine-coordinated membrane-bound ferriheme proteins led to the description of a spectral signal that had only one resolved feature. These became known as "highly anisotropic low-spin" or "large g(max)" ferriheme centers. Extensive work with small-molecule model heme complexes showed that this spectroscopic signature occurs in bis-imidazole ferrihemes in which the planes of the imidazole ligands are nearly perpendicular, deltaphi = 57-90 degrees. In the last decade protein crystallographic studies have revealed the atomic structures of a number of examples of bis-histidine heme proteins. A frequent characteristic of these large g(max) ferrihemes in membrane-bound proteins is the occurrence of the heme within a four-helix bundle with a left-handed twist. The histidine ligands occur at the same level on two diametrically opposed helices of the bundle. These ligands have the same side-chain conformation and ligate heme iron on the bundle axis, resulting in a quasi-twofold symmetric structure. The two non-ligand-bearing helices also obey this symmetry, and have a conserved small residue, usually glycine, where the edge of the heme ring makes contact with the helix backbones. In many cases this small residue is preceded by a threonine or serine residue whose side-chain hydroxyl oxygen acts as a hydrogen-bond acceptor from the N(delta1) atom of the heme-ligating histidine. The deltaphi angle is thus determined by the common histidine side-chain conformation and the crossing angle of the ligand-bearing helices, in some cases constrained by hydrogen bonds to the serine/threonine residues on the non-ligand-bearing helices.
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12
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Zatsman AI, Zhang H, Gunderson WA, Cramer WA, Hendrich MP. Heme-heme interactions in the cytochrome b6f complex: EPR spectroscopy and correlation with structure. J Am Chem Soc 2007; 128:14246-7. [PMID: 17076484 PMCID: PMC2812023 DOI: 10.1021/ja065798m] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome b6f of oxygenic photosynthesis was studied using multifrequency, multimode EPR Spectroscopy. Frequency dependent signals above g = 4.3, and the observation of parallel-mode signals, are indicative of spin interactions in the complex. We demonstrate the presence of an exchange interaction between the unique high-spin heme cn and a nearby low-spin heme bn, and show that a quinone analog NQNO binds at or near to heme cn. The two hemes remain spin coupled upon the binding of NQNO, though strength of interaction decreases significantly. The electronic coupling implies that the heme bn/cn pair could function as a unit to facilitate 2-electron reduction of plastoquionone without generation of an energetically unfavorable semiquinone intermediate.
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13
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Zoppellaro G, Teschner T, Harbitz E, Schünemann V, Karlsen S, Arciero DM, Ciurli S, Trautwein AX, Hooper AB, Andersson KK. Low-temperature EPR and Mössbauer spectroscopy of two cytochromes with His-Met axial coordination exhibiting HALS signals. Chemphyschem 2007; 7:1258-67. [PMID: 16688708 DOI: 10.1002/cphc.200500693] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
C-type cytochromes with histidine-methionine (His-Met) iron coordination play important roles in electron-transfer reactions and in enzymes. Low-temperature electron paramagnetic resonance (EPR) spectra of low-spin ferric cytochromes c can be divided into two groups, depending on the spread of g values: the normal rhombic ones with small g anisotropy and g(max) below 3.2, and those featuring large g anisotropy with g(max) between 3.3 and 3.8, also denoted as highly axial low spin (HALS) species. Herein we present the detailed magnetic properties of cytochrome c(553) from Bacillus pasteurii (g(max) 3.36) and cytochrome c(552) from Nitrosomonas europaea (g(max) 3.34) over the pH range 6.2 to 8.2. Besides being structurally very similar, cytochrome c(553) shows the presence of a minor rhombic species at pH 6.2 (6 %), whereas cytochrome c(552) has about 25 % rhombic species over pH 7.5. The detailed Mössbauer analysis of cytochrome c(552) confirms the presence of these two low-spin ferric species (HALS and rhombic) together with an 8 % ferrous form with parameters comparable to the horse cytochrome c. Both EPR and Mössbauer data of axial cytochromes c with His-Met iron coordination are consistent with an electronic (d(xy))(2) (d(xz))(2) (d(yz))(1) ground state, which is typical for Type I model hemes.
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Affiliation(s)
- Giorgio Zoppellaro
- Department of Molecular Biosciences, University of Oslo, Box 1041 Blindern, 0316 Oslo, Norway
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14
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Adams KL, Tsoi S, Yan J, Durbin SM, Ramdas AK, Cramer WA, Sturhahn W, Alp EE, Schulz C. Fe vibrational spectroscopy of myoglobin and cytochrome f. J Phys Chem B 2006; 110:530-6. [PMID: 16471565 DOI: 10.1021/jp053440r] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Fe vibrational density of states (VDOS) has been determined for the heme proteins deoxymyoglobin, metmyoglobin, and cytochrome f in the oxidized and reduced states, using nuclear resonance vibrational spectroscopy (NRVS). For cytochrome f in particular, the NRVS spectrum is compared with multiwavelength resonance Raman spectra to identify those Raman modes with significant Fe displacement. Modes not seen by Raman due to optical selection rules appear in the NRVS spectrum. The mean Fe force constant extracted from the VDOS illustrates how Fe dynamics varies among these four monoheme proteins, and is correlated with oxidation and spin state trends seen in model heme compounds. The protein's contribution to Fe motion is dominant at low frequencies, where coupling to the backbone tightly constrains Fe displacements in cytochrome f, in contrast to enhanced heme flexibility in myoglobin.
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Affiliation(s)
- Kristl L Adams
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
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15
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Teschner T, Yatsunyk L, Schünemann V, Paulsen H, Winkler H, Hu C, Scheidt WR, Walker FA, Trautwein AX. Models of the membrane-bound cytochromes: mössbauer spectra of crystalline low-spin ferriheme complexes having axial ligand plane dihedral angles ranging from 0 degree to 90 degrees. J Am Chem Soc 2006; 128:1379-89. [PMID: 16433558 PMCID: PMC1525297 DOI: 10.1021/ja056343k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystalline samples of four low-spin Fe(III) octaalkyltetraphenylporphyrinate and two low-spin Fe(III) tetramesitylporphyrinate complexes, all of which are models of the bis-histidine-coordinated cytochromes of mitochondrial complexes II, III, and IV and chloroplast complex b(6)f, and whose molecular structures and EPR spectra have been reported previously, have been investigated in detail by Mössbauer spectroscopy. The six complexes and the dihedral angles between axial ligand planes of each are [(TMP)Fe(1-MeIm)(2)]ClO(4) (0 degree), paral-[(OMTPP)Fe(1-MeIm)(2)]Cl (19.5 degrees), paral-[(TMP)Fe(5-MeHIm)(2)]ClO(4) (26 degrees, 30 degrees for two molecules in the unit cell whose EPR spectra overlap), [(OETPP)Fe(4-Me(2)NPy)(2)]Cl (70 degrees), perp-[(OETPP)Fe(1-MeIm)(2)]Cl (73 degrees), and perp-[(OMTPP)Fe(1-MeIm)(2)]Cl (90 degrees). Of these, the first three have been shown to exhibit normal rhombic EPR spectra, each with three clearly resolved g-values, while the last three have been shown to exhibit "large g(max)" EPR spectra at 4.2 K. It is found that the hyperfine coupling constants of the complexes are consistent with those reported previously for low-spin ferriheme systems, with the largest-magnitude hyperfine coupling constant, A(zz), being considerably smaller for the "parallel" complexes (400-540 kG) than for the strictly perpendicular complex (902 kG), A(xx) being negative for all six complexes, and A(zz) and A(xx) being of similar magnitude for the "parallel" complexes (for example, for [(TMP)Fe(1-MeIm)(2)]Cl, A(zz) = 400 kG, A(xx) = -400 kG). In all cases, A(yy) is small but difficult to estimate with accuracy. With results for six structurally characterized model systems, we find for the first time qualitative correlations of g(zz), A(zz), and DeltaE(Q) with axial ligand plane dihedral angle Deltavarphi.
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Iverson TM. Evolution and unique bioenergetic mechanisms in oxygenic photosynthesis. Curr Opin Chem Biol 2006; 10:91-100. [PMID: 16504567 DOI: 10.1016/j.cbpa.2006.02.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Accepted: 02/16/2006] [Indexed: 11/17/2022]
Abstract
Oxygenic photosynthesis is one example of the many bioenergetic pathways utilized by different organisms to harvest energy from the environment. These pathways revolve around a theme of coupling oxidation-reduction reactions to the formation of membrane potential and subsequent ATP synthesis. Although the basic principles underlying bioenergetics are universally conserved, the constituents of the bioenergetic pathways in different organisms have evolved unique aspects to fill an evolutionary niche. Three-dimensional structures of all of the membrane-spanning components of the electron-transfer chain of oxygenic photosynthesis have revealed those unique aspects of this fascinating process, including the unique metallocofactor for catalysis, the determinants of the uniquely high voltage cofactor, and the numerous photoprotective mechanisms that guard against radical damage.
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Affiliation(s)
- Tina M Iverson
- Department of Pharmacology, Center for Structural Biology and Vanderbilt Institute for Chemical Biology, Vanderbilt University Medical Center, Nashville, TN 37232-6600, USA.
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Walker FA. Models of the Bis-Histidine-Ligated Electron-Transferring Cytochromes. Comparative Geometric and Electronic Structure of Low-Spin Ferro- and Ferrihemes. Chem Rev 2004; 104:589-615. [PMID: 14871136 DOI: 10.1021/cr020634j] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F Ann Walker
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA.
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Kurisu G, Zhang H, Smith JL, Cramer WA. Structure of the cytochrome b6f complex of oxygenic photosynthesis: tuning the cavity. Science 2003; 302:1009-14. [PMID: 14526088 DOI: 10.1126/science.1090165] [Citation(s) in RCA: 497] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The cytochrome b6f complex provides the electronic connection between the photosystem I and photosystem II reaction centers of oxygenic photosynthesis and generates a transmembrane electrochemical proton gradient for adenosine triphosphate synthesis. A 3.0 angstrom crystal structure of the dimeric b6f complex from the thermophilic cyanobacterium Mastigocladus laminosus reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quinone-analog inhibitor, and a novel heme are bound. The core of the b6f complex is similar to the analogous respiratory cytochrome bc1 complex, but the domain arrangement outside the core and the complement of prosthetic groups are strikingly different. The motion of the Rieske iron-sulfur protein extrinsic domain, essential for electron transfer, must also be different in the b6f complex.
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Affiliation(s)
- Genji Kurisu
- Department of Biological Sciences, 915 West State Street, Purdue University, West Lafayette, IN 47907-2054, USA
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Benda R, Schünemann V, Trautwein AX, Cai S, Reddy Polam J, Watson CT, Shokhireva TK, Walker FA. Models of the bis-histidine-coordinated ferricytochromes: Mössbauer and EPR spectroscopic studies of low-spin iron(III) tetrapyrroles of various electronic ground states and axial ligand orientations. J Biol Inorg Chem 2003; 8:787-801. [PMID: 12898323 DOI: 10.1007/s00775-003-0472-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2002] [Accepted: 05/19/2003] [Indexed: 10/26/2022]
Abstract
The EPR and magnetic Mössbauer spectra of a series of axial ligand complexes of tetrakis(2,6-dimethoxyphenyl)porphyrinatoiron(III), [(2,6-(OMe)(2))(4)TPPFeL(2)](+), where L= N-methylimidazole, 2-methylimidazole, or 4-(dimethylamino)pyridine, of one axial ligand complex of tetraphenylporphyrin, the bis(4-cyanopyridine) complex [TPPFe(4-CNPy)(2)](+), and of one axial ligand complex of tetraphenylchlorin, [TPCFe(ImH)(2)](+), where ImH=imidazole, have been investigated and compared to those of low-spin Fe(III) porphyrinates and ferriheme proteins reported in the literature. On the basis of this and previous complementary spectroscopic investigations, three types of complexes have been identified: those having (d(xy))(2)(d(xz),d(yz))(3) electronic ground states with axial ligands aligned in perpendicular planes (Type I), those having (d(xy))(2)(d(xz),d(yz))(3) electronic ground states with axial ligands aligned in parallel planes (Type II), and those having the novel (d(xz),d(yz))(4)(d(xy))(1) electronic ground state (Type III). A subset of the latter type, with planar axial ligands aligned parallel to each other or strong macrocycle asymmetry that yield rhombic EPR spectra, cannot be created using the porphyrinate ligand. Type I centers are characterized by "large g(max)" EPR spectra with g>3.2 and well-resolved, widely spread magnetic Mössbauer spectra having A(zz)/ g(N)mu(N)>680 kG, with A(xx) negative in sign but much smaller in magnitude than A(zz), while Type II centers have well-resolved rhombic EPR spectra with g(zz)=2.4-3.1 and also less-resolved magnetic Mössbauer spectra, and usually have A(zz)/ g(Nmu(N) in the range of 440-660 kG (but in certain cases as small as 180 kG) and A(xx) again negative in sign but only somewhat smaller (but occasionally larger in magnitude) than A(zz), and Type III centers have axial EPR spectra with g( upper left and right quadrants ) approximately 2.6 or smaller and g( vertical line )<1.0-1.95, but often not resolved, and less-resolved magnetic Mössbauer spectra having A(zz)/ g(N)mu(N) in the range of 270-400 kG, and A(xx) again negative in sign but much smaller in magnitude than A(zz). An exception to this rule is [TPPFe(4-CNPy)(2)](+), which has A(xx)/ g(N)mu(N)=-565 kG, A(yy)/ g(N)mu(N)=629 kG, and A(zz)/ g(N)mu(N)=4 kG. A subset of Type II complexes (Type II') have rhombicities ( V/Delta) much greater than 0.67 and A(zz)/ g(N)mu(N) ranging from 320 to 170 kG, with A(xx) also negative but with the magnitude of A(xx) significantly larger than that of A(zz). These classifications are also observed for a variety of ferriheme proteins, and they lead to linear correlations between A(zz) and either A(xx), g(zz), or V/Delta for Types I and II (but not for A(zz) versus V/Delta for Type II'). Not enough data are yet available on Type III complexes to determine what, if any, correlations may be observed.
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Affiliation(s)
- Rüdiger Benda
- Institut für Physik, Universität Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany
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Burda K, Kruk J, Borgstädt R, Stanek J, Strzałka K, Schmid GH, Kruse O. Mössbauer studies of the non-heme iron and cytochrome b559 in a Chlamydomonas reinhardtii PSI- mutant and their interactions with alpha-tocopherol quinone. FEBS Lett 2003; 535:159-65. [PMID: 12560096 DOI: 10.1016/s0014-5793(02)03895-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Spin and valence states of the non-heme iron and the heme iron of cytochrome b559, as well as their interactions with alpha-tocopherol quinone (alpha-TQ) in photosystem II (PSII) thylakoid membranes prepared from the Chlamydomonas reinhardtii PSI- mutant have been studied using Mössbauer spectroscopy. Both of the iron atoms are in low spin ferrous states. The Debye temperature of the non-heme is 194 K and of the heme iron is 182 K. The treatment of alpha-TQ does not change the spin and the valence states of the non-heme iron but enhances the covalence of its bonds. alpha-TQ oxidizes the heme iron into the high spin Fe3+ state. A possible role of the non-heme iron and alpha-TQ in electron flow through the PSII is discussed.
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Affiliation(s)
- Kvetoslava Burda
- Institute of Nuclear Physics, ul. Radzikowskiego 152, 31-342 Cracow, Poland
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Metzler DE, Metzler CM, Sauke DJ. Light and Life. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50026-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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