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Ogawa M, Koskensalo K, Laurila S, Holstila M, Lahesmaa M, Virtanen KA, Iida H, Akima H, Nuutila P. Brown adipose tissue fat-fraction is associated with skeletal muscle adiposity. Eur J Appl Physiol 2021; 122:81-90. [PMID: 34564756 DOI: 10.1007/s00421-021-04816-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 09/17/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE While brown adipose tissue (BAT) activity is known to be associated with both muscle and adipose tissue volumes, the association between BAT and muscle composition remains unclear, especially in adults. Therefore, the present study aimed to examine the association between BAT parameters (glucose uptake and fat-fraction) and muscle volumes and intramuscular adipose tissue contents among healthy young and middle-aged men. METHODS BAT glucose uptake was determined using positron emission tomography with [18F]-2-deoxy-2-fluoro-D-glucose (18F-FDG) during cold exposure in 19 young and middle-aged men (36.3 ± 10.7 years). The fat-fraction of BAT was determined from volumes of interest set in cervical and supraclavicular adipose tissue depots using signal fat-fraction maps via magnetic resonance imaging (MRI). Muscle volumes and intramuscular adipose tissue contents of m. tibialis anterior and m. multifidus lumborum were measured using MRI. RESULTS The fat-fraction of BAT was significantly associated with intramuscular adipose tissue content in m. tibialis anterior (n = 13, rs = 0.691, P = 0.009). A similar trend was also observed in m. multifidus lumborum (n = 19, rs = 0.454, P = 0.051). However, BAT glucose uptake was not associated with intramuscular adipose tissue contents in both muscles, nor were muscle volumes associated with the BAT glucose uptake and fat-fraction. CONCLUSION The fat-fraction of BAT increases with skeletal muscle adiposity, especially in the lower leg, among healthy young and middle-aged men.
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Affiliation(s)
- Madoka Ogawa
- Graduate School of Education and Human Development, Nagoya University, Aichi, Japan. .,Nippon Sport Science University, Tokyo, Japan. .,Kyoto Sangyo University, Kyoto, Japan.
| | - Kalle Koskensalo
- Turku PET centre, University of Turku, Turku, Finland.,Turku PET centre, Turku University Hospital, Turku, Finland.,Department of Medical Physics, Turku University Hospital, Turku, Finland.,Heart Center, Turku University Hospital, Turku, Finland
| | - Sanna Laurila
- Turku PET centre, University of Turku, Turku, Finland.,Turku PET centre, Turku University Hospital, Turku, Finland.,Heart Center, Turku University Hospital, Turku, Finland.,Satakunta Central Hospital, Pori, Finland
| | - Milja Holstila
- Turku PET centre, University of Turku, Turku, Finland.,Turku PET centre, Turku University Hospital, Turku, Finland.,Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland
| | - Minna Lahesmaa
- Turku PET centre, University of Turku, Turku, Finland.,Turku PET centre, Turku University Hospital, Turku, Finland
| | - Kirsi A Virtanen
- Turku PET centre, Turku University Hospital, Turku, Finland.,Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland
| | - Hidehiro Iida
- Turku PET centre, University of Turku, Turku, Finland.,Turku PET centre, Turku University Hospital, Turku, Finland
| | - Hiroshi Akima
- Graduate School of Education and Human Development, Nagoya University, Aichi, Japan.,Research Center of Health, Physical Fitness and Sports, Nagoya University, Aichi, Japan
| | - Pirjo Nuutila
- Turku PET centre, University of Turku, Turku, Finland.,Turku PET centre, Turku University Hospital, Turku, Finland.,Department of Endocrinology, Turku University Hospital, Turku, Finland
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2
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Taylor RM, Sallans L, Frankel LK, Bricker TM. Natively oxidized amino acid residues in the spinach cytochrome b 6 f complex. PHOTOSYNTHESIS RESEARCH 2018; 137:141-151. [PMID: 29380263 DOI: 10.1007/s11120-018-0485-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/18/2018] [Indexed: 05/25/2023]
Abstract
The cytochrome b 6 f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b 6 f is 10-20 fold higher than that observed for the analogous respiratory cytochrome bc1 complex. The types of ROS produced (O2•-, 1O2, and, possibly, H2O2) and the site(s) of ROS production within the b 6 f complex have been the subject of some debate. Proposed sources of ROS have included the heme b p , PQ p•- (possible sources for O2•-), the Rieske iron-sulfur cluster (possible source of O2•- and/or 1O2), Chl a (possible source of 1O2), and heme c n (possible source of O2•- and/or H2O2). Our working hypothesis is that amino acid residues proximal to the ROS production sites will be more susceptible to oxidative modification than distant residues. In the current study, we have identified natively oxidized amino acid residues in the subunits of the spinach cytochrome b 6 f complex. The oxidized residues were identified by tandem mass spectrometry using the MassMatrix Program. Our results indicate that numerous residues, principally localized near p-side cofactors and Chl a, were oxidatively modified. We hypothesize that these sites are sources for ROS generation in the spinach cytochrome b 6 f complex.
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Affiliation(s)
- Ryan M Taylor
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Larry Sallans
- The Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Laurie K Frankel
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Terry M Bricker
- Department of Biological Sciences, Biochemistry and Molecular Biology Section, Louisiana State University, Baton Rouge, LA, 70803, USA.
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3
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Romanowska E. Isolation of cytochrome b6f complex from grana and stroma membranes from spinach chloroplasts. Methods Mol Biol 2011; 684:53-64. [PMID: 20960121 DOI: 10.1007/978-1-60761-925-3_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The cytochrome b6f complex is located in the appressed granal membranes and nonappressed stroma thylakoids. The procedure presents isolation of the complex from both types of thylakoids by washing with NaBr, detergent treatment, ammonium sulfate fractionation, and sucrose gradient centrifugation. Optimal concentration of the detergent is lower for grana than for stroma vesicles. The cytochrome b6f complex from stroma lamellae locates at a higher density in the sucrose gradient than the granal complex. Electrophoretic analyses indicate that both complexes are dimeric and contain four large subunits and at least three small subunits with masses below 4 kDa. Plastocyanin and 15 kDa protein are also identified in the complexes but in variable amounts.
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4
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Baniulis D, Zhang H, Zakharova T, Hasan SS, Cramer WA. Purification and crystallization of the cyanobacterial cytochrome b6f complex. Methods Mol Biol 2011; 684:65-77. [PMID: 20960122 DOI: 10.1007/978-1-60761-925-3_7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The cytochrome b6f complex from the filamentous cyanobacteria (Mastigocladus laminosus, Nostoc sp. PCC 7120) and spinach chloroplasts has been purified as a homo-dimer. Electrospray ionization mass spectroscopy showed the monomer to contain eight and nine subunits, respectively, and dimeric masses of 217.1, 214.2, and 286.5 kDa for M. laminosus, Nostoc, and the complex from spinach. The core subunits containing or interacting with redox-active prosthetic groups are petA (cytochrome f), B (cytochrome b6, C (Rieske iron-sulfur protein), D (subunit IV), with protein molecular weights of 31.8-32.3, 24.7-24.9, 18.9-19.3, and 17.3-17.5 kDa, and four small 3.2-4.2 kDa polypeptides petG, L, M, and N. A ninth polypeptide, the 35 kDa petH (FNR) polypeptide in the spinach complex, was identified as ferredoxin:NADP reductase (FNR), which binds to the complex tightly at a stoichiometry of approx 0.8/cytf. The spinach complex contains diaphorase activity diagnostic of FNR and is active in facilitating ferredoxin-dependent electron transfer from NADPH to the cytochrome b6f complex. The purified cytochrome b6f complex contains stoichiometrically bound chlorophyll a and β-carotene at a ratio of approximately one molecule of each per cytochrome f. It also contains bound lipid and detergent, indicating seven lipid-binding sites per monomer. Highly purified complexes are active for approximately 1 week after isolation, transferring 200-300 electrons/cytf s. The M. laminosus complex was shown to be subject to proteolysis and associated loss of activity if incubated for more than 1 week at room temperature. The Nostoc complex is more resistant to proteolysis. Addition of pure synthetic lipid to the cyanobacterial complex, which is mostly delipidated by the isolation procedure, allows rapid formation of large (≥0.2 mm) crystals suitable for X-ray diffraction analysis and structure determination. The crystals made from the cyanobacterial complex diffract to 3.0 Å with R values of 0.222 and 0.230 for M. laminosus and Nostoc, respectively. It has not yet been possible to obtain crystals of the b6f complex from any plant source, specifically spinach or pea, perhaps because of incomplete binding of FNR or other peripheral polypeptides. Well diffracting crystals have been obtained from the green alga, Chlamydomonas reinhardtii (ref. 10).
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Affiliation(s)
- Danas Baniulis
- Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, West Lafayette, IN, USA
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5
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Chen X, Zhao X, Zhang J, Li L, Kuang T. The effects of detergents DDM and beta-OG on the singlet excited state lifetime of the chlorophyll a in cytochrome b6f complex from spinach chloroplasts. SCIENCE IN CHINA. SERIES C, LIFE SCIENCES 2007; 50:505-10. [PMID: 17653672 DOI: 10.1007/s11427-007-0047-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Accepted: 11/02/2006] [Indexed: 10/23/2022]
Abstract
The singlet excited state lifetime of the chlorophyll a (Chl a) in cytochrome b(6)f (Cyt b(6)f) complex was reported to be shorter than that of free Chl a in methanol, but the value was different for Cyt b(6)f complexes from different sources ( approximately 200 and approximately 600 ps are the two measured results). The present study demonstrated that the singlet excited state lifetime is associated with the detergents n-dodecyl-beta-D-maltoside (DDM) and n-octyl-beta-D-glucopyranoside (beta-OG), but has nothing to do with the different sources of Cyt b(6)f complexes. Compared with the Cyt b(6)f dissolved in beta-OG, the Cyt b(6)f in DDM had a lower fluorescence yield, a lower photodegradation rate of Chl a, and a shorter lifetime of Chl a excited state. In short, the singlet excited state lifetime, approximately 200 ps, of the Chl a in Cyt b(6)f complex in DDM is closer to the true in vivo.
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Affiliation(s)
- XiaoBo Chen
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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6
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Chen XB, Zhao XH, Zhu Y, Gong YD, Li LB, Zhang JP, Kuang TY. Hydrogen peroxide-induced chlorophyll a bleaching in the cytochrome b6f complex: a simple and effective assay for stability of the complex in detergent solutions. PHOTOSYNTHESIS RESEARCH 2006; 90:205-14. [PMID: 17235492 DOI: 10.1007/s11120-006-9118-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2006] [Accepted: 11/20/2006] [Indexed: 05/10/2023]
Abstract
The instability of cytochrome b ( 6 ) f complex in detergent solutions is a well-known problem that has been studied extensively, but without finding a satisfactory solution. One of the important reasons can be short of the useful method to verify whether the complex suspended in different detergent is in an intact state or not. In this article, a simple and effective assay for stability of the complex was proposed based on the investigation on the different effects of the two detergents, n-octyl-beta-D: -glucopyranoside (OG) and dodecyl-beta-D: -maltoside (DDM), on the properties of the complex. DDM stabilizes the complex preparation more effectively whereas OG denatures the interactions of the heme groups and pigment molecules with the protein environment, leading to the bleaching of chlorophyll a induced by addition of hydrogen peroxide. The assay of the use of hydrogen peroxide to characterize the complex by studying the bleaching of chlorophyll induced by hydrogen peroxide and the peroxidase activity of the complex was discussed. This simple method will probably be useful to study the stability of the complex.
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Affiliation(s)
- Xiao-Bo Chen
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Nan Xincun 20, Xiangshan, 100093, Beijing, P.R. China
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7
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Li B, Mao D, Liu Y, Li L, Kuang T. Characterization of the cytochrome b(6)f complex from marine green alga, Bryopsis corticulans. PHOTOSYNTHESIS RESEARCH 2005; 83:297-305. [PMID: 16143919 DOI: 10.1007/s11120-004-6555-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 11/22/2004] [Indexed: 05/04/2023]
Abstract
A pure, active cytochrome b(6)f was isolated from the chloroplasts of the marine green alga, Bryopsis corticulans. To investigate and characterize this cytochrome b(6)f complex, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), absorption spectra measurement and HPLC were employed. It was shown that this purified complex contained four large subunits with apparent molecular masses of 34.8, 24, 18.7 and 16.7 kD. The ratio of Cyt (6) to Cyt f was 2.01 : 1. The cytochrome b(6) f was shown to catalyze the transfer of 73 electrons from decylplastoquinol to plastocyanin-ferricyanide per Cyt f per second. alpha-Carotene, one kind of carotenoid that has not been found to present in cytochrome b(6)f complex, was discovered in this preparation by reversed phase HPLC. It was different from beta-carotene usually found in cytochrome b(6)f complex. The configuration of the major alpha-carotene component was assigned to be 9-cis by resonance Raman spectroscopy. Different from the previous reports, the configuration of this alpha-carotene in dissociated state was determined to be all-trans. Besides this carotene, chlorophyll a was also found in this complex. It was shown that the molecular ratios of chlorophyll a, cis and all-trans-alpha-carotene to Cyt f in this complex were 1.2, 0.7 and 0.2, respectively.
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Affiliation(s)
- Binxing Li
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing.
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8
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Cramer WA, Yan J, Zhang H, Kurisu G, Smith JL. Structure of the cytochrome b6f complex: new prosthetic groups, Q-space, and the 'hors d'oeuvres hypothesis' for assembly of the complex. PHOTOSYNTHESIS RESEARCH 2005; 85:133-43. [PMID: 15977064 DOI: 10.1007/s11120-004-2149-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 08/13/2004] [Indexed: 05/03/2023]
Abstract
3-A crystal structures of the cytochrome b6f complex have provided a structural framework for the photosynthetic electron transport chain. The structures of the 220,000 molecular weight dimeric cytochrome b6f complex from the thermophilic cyanobacterium, Mastigocladis laminosus (Kurisu et al. 2003, Science 302: 1009-1014), and the green alga, Chlamydomonas reinhardtii (Stroebel et al. 2003, Nature 426: 413-418), are very similar. The latter is the first structure of a integral membrane photosynthetic electron transport complex from a eukaryotic source. The M. laminosus and C. reinhardtii structures have provided structural information and experimental insights to the properties and functions of three native and novel prosthetic groups, a chlorophyll a, a beta-carotene, and a unique heme x, one copy of which is found in each monomer of the cytochrome b6f complex, but not the cytochrome bc1 complex from the mitochondrial respiratory chain of animals and yeast. Several functional insights have emerged from the structures including the function of the dimer; the properties of heme x; the function of the inter-monomer quinone-exchange cavity; a quinone diffusion pathway through relatively narrow crevices or portals; a modified reaction scheme for n-side quinone redox reactions; a necessarily novel mechanism for quenching of the bound chlorophyll triplet state; a possible role for the bound chlorophyll a in activation of the LHC kinase; and a structural and assembly role for the four small PetG, L, M, and N subunits. An 'hors d'oeuvres hypothesis' for assembly of the complex is proposed for the small 'hydrophobic stick' or 'picket fence' polypeptides at the periphery of the complex, based on the cis-positive orientation of the small hydrophobic subunits and the 'toothpick' binding mode of the beta-carotene.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA
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9
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Gubernator B, Seidler A, Rögner M, Szczepaniak A. Overexpression and reconstitution of a Rieske iron-sulfur protein from the higher plant. Protein Expr Purif 2003; 29:8-14. [PMID: 12729720 DOI: 10.1016/s1046-5928(03)00016-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The iron-sulfur protein subunit, known as the Rieske protein, is one of the central components of the cytochrome b(6)f complex residing in chloroplast and cyanobacterial thylakoid membranes. We have constructed plasmids for overexpression in Escherichia coli of full-length and truncated Rieske (PetC) proteins from the Spinacia oleracea fused to MalE. Overexpressed fusion proteins were predominantly found (from 55 to 70%) in cytoplasm in a soluble form. The single affinity chromatography step (amylose resine) was used to purify about 15mg of protein from 1 liter of E. coli culture. The isolated proteins were electrophoretically pure and could be used for further experiments. The NifS-like protein IscS from the cyanobacterium Synechocystis PCC 6803 mediates the incorporation of 2Fe-2S clusters into apoferredoxin and cyanobacterial Rieske apoprotein in vitro. Here, we used the recombinant IscS protein for the enzymatic reconstitution of the iron-sulfur cluster into full-length Rieske fusion and truncated Rieske fused proteins. Characterization by EPR spectroscopy of the reconstituted proteins demonstrated the presence of a 2Fe-2S cluster in both full-length and truncated Rieske fusion proteins.
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Affiliation(s)
- Beata Gubernator
- Institute of Biochemistry and Molecular Biology, Wrocław University, Tamka 2, 50-137 Wrocław, Poland
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10
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Abstract
The cytochrome bc complexes represent a phylogenetically diverse group of complexes of electron-transferring membrane proteins, most familiarly represented by the mitochondrial and bacterial bc1 complexes and the chloroplast and cyanobacterial b6f complex. All these complexes couple electron transfer to proton translocation across a closed lipid bilayer membrane, conserving the free energy released by the oxidation-reduction process in the form of an electrochemical proton gradient across the membrane. Recent exciting developments include the application of site-directed mutagenesis to define the role of conserved residues, and the emergence over the past five years of X-ray structures for several mitochondrial complexes, and for two important domains of the b6f complex.
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Affiliation(s)
- E A Berry
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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11
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Illerhaus J, Altschmied L, Reichert J, Zak E, Herrmann RG, Haehnel W. Dynamic interaction of plastocyanin with the cytochrome bf complex. J Biol Chem 2000; 275:17590-5. [PMID: 10837495 DOI: 10.1074/jbc.275.23.17590] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The interaction between plastocyanin and the intact cytochrome bf complex, both from spinach, has been studied by stopped-flow kinetics with mutant plastocyanin to elucidate the site of electron transfer and the docking regions of the molecule. Mutation of Tyr-83 to Arg or Leu provides no evidence for a second electron transfer path via Tyr-83 of plastocyanin, which has been proposed to be the site of electron transfer from cytochrome f. The data found with mutations of acidic residues indicate that both conserved negative patches are essential for the binding of plastocyanin to the intact cytochrome bf complex. Replacing Ala-90 and Gly-10 at the flat hydrophobic surface of plastocyanin by larger residues slowed down and accelerated, respectively, the rate of electron transfer as compared with wild-type plastocyanin. These opposing effects reveal that the hydrophobic region around the electron transfer site at His-87 is divided up into two regions, of which only that with Ala-90 contributes to the attachment to the cytochrome bf complex. These binding sites of plastocyanin are substantially different from those interacting with photosystem I. It appears that each of the two binding regions of plastocyanin is split into halves, which are used in different combinations in the molecular recognition at the two membrane complexes.
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Affiliation(s)
- J Illerhaus
- Institut für Biologie II/Biochemie, Albert-Ludwigs-Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany
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12
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Dietrich J, Kühlbrandt W. Purification and two-dimensional crystallization of highly active cytochrome b(6)f complex from spinach. FEBS Lett 1999; 463:97-102. [PMID: 10601646 DOI: 10.1016/s0014-5793(99)01609-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The purification and two-dimensional crystallization of highly active cytochrome b(6)f complex from spinach is described. The preparation shows all spectroscopic characteristics of the pure complex. The electron transfer activity of 450+/-60 electrons per s is the highest in vitro activity reported to date. Using dimethyl sulfoxide (DMSO) as a solvent for the electron donor enhanced the performance and reproducibility of the assay. The high yield and the high activity of the protein make it an ideal candidate for biophysical and structural studies. Preliminary two-dimensional crystallization experiments yielded several different forms of two-dimensional and thin three-dimensional crystals, exhibiting varying degrees of order.
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Affiliation(s)
- J Dietrich
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Heinrich-Hoffmann-Strasse 7, 60528, Frankfurt am Main, Germany
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13
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Hippler M, Redding K, Rochaix JD. Chlamydomonas genetics, a tool for the study of bioenergetic pathways. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1367:1-62. [PMID: 9784589 DOI: 10.1016/s0005-2728(98)00136-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- M Hippler
- Departments of Molecular Biology and Plant Biology, University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva-4, Switzerland
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14
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Zhang H, Carrell CJ, Huang D, Sled V, Ohnishi T, Smith JL, Cramer WA. Characterization and crystallization of the lumen side domain of the chloroplast Rieske iron-sulfur protein. J Biol Chem 1996; 271:31360-6. [PMID: 8940143 DOI: 10.1074/jbc.271.49.31360] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A soluble, 139-residue COOH-terminal polypeptide fragment of the Rieske iron-sulfur protein of the cytochrome b6f complex from spinach chloroplasts was obtained by limited proteolysis of the complex and a two-step chromatography purification protocol. The purified Rieske iron-sulfur protein fragment was characterized by: (i) a single NH2-terminal sequence, NH2-Phe-Val-Pro-Pro-Gly-Gly, starting with residue 41 of the intact Rieske protein; (ii) a single molecular weight species determined by mass spectrometry with a molecular weight of 14,620 +/- 2 without the [2Fe-2S] cluster; (iii) an optical absorbance spectrum with redox- and pH-dependent maxima and minima; and (iv) a reduced-oxidized optical difference spectrum characterized by DeltaepsilonmM = 3.8 mM-1 cm-1 for DeltaA at 394 versus 409 nm, which was used to determine the midpoint oxidation-reduction potential, which is +359 +/- 7 mV at 25 degrees C from pH 5.5-6.5, and +319 +/- 2 mV at pH 7, with an apparent pKox = 6.5 +/- 0.2 for the oxidized protein. The EPR spectrum measured at 17 K was characterized by the g values, gz = 2.03 and gy = 1.90, and a broad band centered at gx approximately 1.74, very similar or identical to those of the Rieske cluster in the b6f complex, implying that the environment of the [2Fe-2S] cluster is similar to that in the complex. Midpoint potential determination by low temperature EPR yielded a redox midpoint potential (Em) of +365-375 mV of the soluble Rieske fragment at pH 6 and 7 and an Em of +295-300 mV of the Rieske cluster in the cytochrome b6f complex at pH 6 and 7. The Em difference implies that the environment of the cluster in the soluble Rieske fragment is slightly more polar than that of the cluster in the intact complex. Single crystals of the Rieske polypeptide were obtained that are capable of x-ray diffraction to atomic resolution (<2.5 A), contain one molecule per asymmetric unit, a solvent content of approximately 30%, and belong to the triclinic space group P1 with cell dimensions, a = 29.1 A, b = 31.9 A, c = 35.8 A, alpha = 95.6 degrees, beta = 107.1 degrees, gamma = 117.3 degrees.
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Affiliation(s)
- H Zhang
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA.
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15
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Pierre Y, Breyton C, Kramer D, Popot JL. Purification and characterization of the cytochrome b6 f complex from Chlamydomonas reinhardtii. J Biol Chem 1995; 270:29342-9. [PMID: 7493968 DOI: 10.1074/jbc.270.49.29342] [Citation(s) in RCA: 155] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A protocol has been developed for the purification of the cytochrome b6 f complex from the unicellular alga Chlamydomonas reinhardtii. It is based on the use of the neutral detergent Hecameg (6-O-(N-heptylcarbamoyl)-methyl-alpha-D-glycopyranoside) and comprises only three steps: selective solubilization from thylakoid membranes, sucrose gradient sedimentation, and hydroxylapatite chromatography. The purified complex contains two b hemes (alpha bands, 564 nm; Em,8 = -84 and -158 mV) and one chlorophyll alpha (lambda max = 667-668 nm) per cytochrome f (alpha band, 554 nm; Em,8 = +330 mV). It is highly active in transferring electrons from decylplastoquinol to oxidized plastocyanin (turnover number 250-300 s-1). The purified complex contains seven subunits, whose identity has been established by N-terminal sequencing and/or peptide-specific immunolabeling, namely four high molecular weight subunits (cytochrome f, Rieske iron-sulfur protein, cytochrome b6, and subunit IV) and three approximately 4-kDa miniproteins (PetG, PetL, and PetX). Stoichiometry measurements are consistent with every subunit being present as two copies per b6 f dimer.
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Affiliation(s)
- Y Pierre
- Institut de Biologie Physico-Chimique, CNRS URA 1187, Paris, France
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16
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Huang D, Everly RM, Cheng RH, Heymann JB, Schägger H, Sled V, Ohnishi T, Baker TS, Cramer WA. Characterization of the chloroplast cytochrome b6f complex as a structural and functional dimer. Biochemistry 1994; 33:4401-9. [PMID: 8155658 PMCID: PMC4167635 DOI: 10.1021/bi00180a038] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Size analysis of the cytochrome b6f complex by FPLC Superose-12 chromatography and Blue Native PAGE indicated a predominantly dimeric component with M(r) = (1.9-2.5) x 10(5). The true dimer molecular weight including bound lipid, but not detergent, was estimated to be 2.3 x 10(5). Size and shape analysis by negative-stain single-particle electron microscopy indicated that the preparation of dimeric complexes contains a major population that has a protein cross section 40% larger than the monomer, binds more negative stain, and has a geometry with a distinct 2-fold axis of symmetry compared to the monomeric complex. The dimeric species is more stable at higher ionic strength with respect to conversion to the monomeric species. SDS-PAGE of monomer and dimer preparations indicated that both contain the four major polypeptides in approximately equal stoichiometry and also contain the petG M(r) 4000 subunit. One bound chlorophyll a per monomer, part of the bound lipid, is present in monomer and dimer. The in vitro electron-transport activity (decyl-PQH2-->PC-ferricyanide) of the separated dimer was comparable to that of the isolated b6f complex and was 4-5-fold greater than that of the monomer preparation, whose activity could be attributed to residual dimer. No difference in the properties of the dimer and monomer was detected by SDS-PAGE or redox difference spectrophotometry that could account for the difference in activities. However, the concentration of the Rieske [2Fe-2S] center was found by EPR analysis of the gy = 1.90 signal to be lower in the monomer fraction by a factor of 3.5 relative to the dimer.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
| | | | | | | | | | | | | | | | - W. A. Cramer
- To whom correspondence should be addressed: Telephone: 317-494-4956. FAX: 317-494-0876.
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17
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Hope AB. The chloroplast cytochrome bf complex: a critical focus on function. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1143:1-22. [PMID: 8388722 DOI: 10.1016/0005-2728(93)90210-7] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- A B Hope
- School of Biological Sciences, Flinders University, Adelaide, Australia
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18
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Li LB, Yu L, Yu CA. Inhibitory effects of dicyclohexylcarbodiimide on spinach cytochrome b6-f complex. Biochem Biophys Res Commun 1991; 179:507-11. [PMID: 1883376 DOI: 10.1016/0006-291x(91)91400-7] [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: 12/29/2022]
Abstract
The electron transfer activity of purified cytochrome b6-f complex of spinach chloroplast is inhibited by dicyclohexylcarbodiimide (DCCD) in a concentration and incubation time dependent manner. The maximum inhibition of 75% is observed when 300 mole of DCCD per mole of protein (based on cytochrome f) is incubated with cytochrome b6-f complex at room temperature for 40 min. The inhibition of the complex is not due to the formation of cross links between subunits but due to the modification of carboxyls. The amount of DCCD incorporation is directly proportional to the activity loss, suggesting that some carboxyl groups in the complex are directly or indirectly involved in the catalytic function. The incorporated DCCD is located mainly at cytochrome b6 protein. The partially inhibited complex shows the same H+/e-ratio as that of the intact complex when embedded in phospholipid vesicles.
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Affiliation(s)
- L B Li
- Department of Biochemistry, OAES, Oklahoma State University, Stillwater 74078
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19
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Hobbs JD, Wynn M, Nunez DJ, Malkin R, Knaff DB, Ondrias MR. Structural characterization of heme sites in spinach cytochrome b6f complexes: a resonance Raman study. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1059:37-44. [PMID: 1873297 DOI: 10.1016/s0005-2728(05)80185-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Resonance Raman spectra of cytochrome b6f complexes isolated from spinach chloroplasts have been obtained. Selective resonance enhancements and partial reductions of the complex by redox mediators were used to isolate and identify the contributions of heme b6 and heme f sites to the observed spectra. Corresponding spectra for turnip cytochrome f have also been obtained. Power-dependent photoreduction was observed in cytochrome f of the complex as well as in the isolated cytochrome f during the course of the Raman experiments.
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Affiliation(s)
- J D Hobbs
- Department of Chemistry, University of New Mexico, Albuquerque 87131
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20
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Li LB, Zou YP, Yu L, Yu CA. The catalytic role of subunit IV of the cytochrome b6-f complex from spinach chloroplast. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1057:215-22. [PMID: 2015249 DOI: 10.1016/s0005-2728(05)80104-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The catalytic role of subunit IV, the Mr 17,000 protein, in the chloroplast cytochrome b6-f complex was established through trypsinolysis of the complex under controlled conditions. When purified chloroplast cytochrome b6-f complex, 1 mg/ml, in 50 mM Tris-succinate buffer (pH 7.0) containing 1% sodium cholate and 10% glycerol is treated with 80 micrograms of trypsin at room temperature for various lengths of time, the activity of the cytochrome b6-f complex decreases as the incubation time increases. A maximal inactivation of 80% is reached at 7 min of incubation. The trypsin inactivation is accompanied by the destruction of the proton translocation activity of the complex. No alteration of absorption and EPR spectral properties was observed in the trypsin-inactivated complex. Subunit IV is the only subunit in the cytochrome b6-f complex that is digested by trypsin, and the degree of digestion correlates with the decrease of electron transfer activity. The binding of azido-Q to subunit IV of the complex decreases as the extent of inactivation of the cytochrome b6-f complex by trypsin increases. The residue molecular mass of trypsin cleaved subunit IV is about 14 kDa, suggesting that the cleavage site is at lysine 119 or arginine 125 or 126. When the thylakoid membrane was assayed for cytochrome b6-f complex activity, very little activity was observed; and the activity was not sensitive to trypsinolysis. Upon sonication, activity and sensitivity to trypsinolysis was greatly increased, suggesting that subunit IV protrudes from the lumen side of the membrane.
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Affiliation(s)
- L B Li
- Department of Biochemistry, OAES, Oklahoma State University, Stillwater 74078
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21
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Mohamed Shallan MAA, Radau B, Salnikow J, Vater J. Topological analysis of components of the cytochrome b6f complex by chemical crosslinking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(05)80084-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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22
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Szczepaniak A, Cramer WA. Thylakoid membrane protein topography. Location of the termini of the chloroplast cytochrome b6 on the stromal side of the membrane. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)38223-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Allnutt FC, Atta-Asafo-Adjei E, Dilley RA. Chloroplast thylakoid proteins associated with sequestered proton-buffering domains. Plastocyanin contributes buffering groups to localized proton domains. J Bioenerg Biomembr 1989; 21:535-51. [PMID: 2553685 DOI: 10.1007/bf00762525] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Thylakoid membrane proteins are organized so as to shield 30-50 nmol H+ (mg Chl)-1 from freely equilibrating with either the external or the lumen aqueous phases. Amine groups provide binding sites for this metastable buffering array and can be quantitatively measured by acetylation using [3H]acetic anhydride. The principle of the assay is that a metastable acidic domain will have relatively less of the reactive neutral form of the amine compared to the amount present after addition of an uncoupler. The extent of the acetylation reaction is strongly influenced by whether the lumen pH comes to complete equilibrium with the external pH prior to adding the acetic anhydride. Determination of the lumen pH by [14C]methylamine distribution after the standard 3 or 5 min equilibration in pH 8.6 buffer indicated that the lumen may have been 0.2 to 0.3 pH more acidic than the external phase. This effect was taken into account by determining the pH dependence, in the pH 8.2-8.6 range, of acetylation of the membrane proteins studied, and the labeling data were conservatively corrected for this possible contribution. Experiments were carried out to identify the thylakoid proteins that contribute such metastable domain amine groups, using the above conservative correction. Surprisingly, plastocyanin contributes buried amine groups, but cytochrome f did not give evidence for such a contribution, if the conservative correction in the labeling was applied. If the correction was too conservative, cytochrome f may contribute amines to the sequestered domains. The new methodology verified earlier results suggesting that three Tris-releasable photosystem II-associated proteins also contribute significantly to the sequestered amine-buffering array.
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Affiliation(s)
- F C Allnutt
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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24
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Doyle MP, Li LB, Yu L, Yu CA. Identification of a Mr = 17,000 Protein as the Plastoquinone-binding Protein in the Cytochrome b6-f Complex from Spinach Chloroplasts. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94199-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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25
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Wynn RM, Bertsch J, Bruce BD, Malkin R. Green algal cytochrome b6-f complexes: isolation and characterization from Dunaliella saline, Chlamydomonas reinhardtii and Scenedesmus obliquus. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 935:115-22. [PMID: 3415983 DOI: 10.1016/0005-2728(88)90208-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cytochrome b6-f complexes have been isolated from Chlamydomonas reinhardtii, Dunaliella saline and Scenedesmus obliquus. Each complex is essentially free of chlorophyll and carotenoids and contains cytochrome b6 and cytochrome f hemes in a 2:1 molar ratio. C. reinhardtii and S. obliquus complexes contain the Rieske iron-sulfur protein (present in approx 1:1 molar ratio to cytochrome f) and each catalyzes a DBMIB- and DNP-INT-sensitive electron transfer from duroquinol to spinach plastocyanin. Immunological assays using antibodies to the peptides from the spinach cytochrome complex show varying cross-reactivity patterns except for the complete absence of binding to the Rieske proteins in any of the three complexes, suggesting little structural similarity between the Rieske proteins of algae with those from higher plants. One complex (D. salina) has been uniformly labeled by growth in NaH14CO3 to determine stoichiometries of constituent polypeptide subunits. Results from these studies indicate that all functionally active cytochrome b6-f complexes contain four subunits which occur in equimolar amounts.
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Affiliation(s)
- R M Wynn
- Division of Molecular Plant Biology, University of California, Berkeley 94720
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26
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O'Keefe DP. Structure and function of the chloroplast cytochrome bf complex. PHOTOSYNTHESIS RESEARCH 1988; 17:189-216. [PMID: 24429768 DOI: 10.1007/bf00035448] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/1987] [Accepted: 02/02/1988] [Indexed: 06/03/2023]
Abstract
The chloroplast cytochrome bf complex is an intrinsic multisubunit protein from the thylakoid membrane consisting of four polypeptides: cytochrome f, a two heme containing cytochrome b 6, the Rieske iron-sulfur protein, and a 17 kD polypeptide of undefined function. The complex functions in electron transfer between PSII and PSI, where most mechanisms suggest that the transfer of a single reducing equivalent from plastoquinol to plastocyanin results in the translocation of two protons across the membrane. Primary sequence analyses, dichroism studies, and functional considerations allow the construction of an approximate structural model of a monomeric complex, although some evidence exists for a dimeric structure. Resolution of the properties of the two cytochrome b 6 hemes has relied upon the availability of purified solubilized complex, while evidence in the thylakoid suggests the difference between the two hemes are not as great in situ. Such variability in the spectroscopic and electrochemical properties of the cytochrome b 6 is a major concern during the experimental use of the purified complex. There is a general consensus that the complex contains a plastoquinol oxidizing (Qz) site, although the evidence for a plastoquinone reduction (Qc) site, called for in most mechanistic hypotheses, is less substantive. Probably the most severe challenge to the so called Q-cycle mechanism comes from experimental observations made with cytochrome b 6 initially reduced, where proposed interpretations more closely resemble a b-cycle than a Q-cycle. Although functional during cyclic electron transfer, the role of the complex and its possible interaction with other proteins, has not been completely resolved.
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Affiliation(s)
- D P O'Keefe
- Central Research and Development Department, E.I. duPont de Nemours and Company, Inc. Experimental Station, Bldg. 402, 19898, Wilmington, DE, USA
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27
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el-Demerdash M, Salnikow J, Vater J. Evidence for a cytochrome f-Rieske protein subcomplex in the cytochrome b6f system from spinach chloroplasts. Arch Biochem Biophys 1988; 260:408-15. [PMID: 3277532 DOI: 10.1016/0003-9861(88)90464-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The cytochrome b6f complex of spinach chloroplasts was prepared with minor modification according to the method of E. Hurt and G. Hauska (1981) Eur. J. Biochem. 117, 591-599) replacing, however, the final ultracentrifugation step by hydroxyapatite chromatography as suggested by M. F. Doyle and C.-A Yu (1985) Biochem. Biophys. Res. Commun. 131, 700-706). The purified complex was partially dissociated by treatment with 4 M urea or 0.1% sodium dodecyl sulfate (SDS) in the absence of reducing agents. A binary subcomplex consisting of cytochrome f and the Rieske iron-sulfur protein was observed under these conditions by three different methods: (a) hydroxyapatite chromatography; (b) extraction with an isopropanol/water/trifluoroacetic acid mixture; and (c) gel filtration in the presence of low SDS concentrations. The subcomplex dissociated into its components by treatment with mercaptoethanol. These results suggest a close interaction of the cytochrome f with the Rieske protein involving SH groups which under reducing conditions leads to complete dissociation of the subcomplex.
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Affiliation(s)
- M el-Demerdash
- Technical University Berlin, Institute of Biochemistry and Molecular Biology, West Germany
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