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Silkstone G, Kapetanaki SM, Husu I, Vos MH, Wilson MT. Nitric oxide binding to the cardiolipin complex of ferric cytochrome C. Biochemistry 2012; 51:6760-6. [PMID: 22803508 DOI: 10.1021/bi300582u] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cardiolipin, a phospholipid specific to the mitochondrion, interacts with the small electron transfer heme protein cytochrome c through both electrostatic and hydrophobic interactions. Once in a complex with cardiolipin, cytochrome c has been shown to undergo a conformational change that leads to the rupture of the bond between the heme iron and the intrinsic sulfur ligand of a methionine residue and to enhance the peroxidatic properties of the protein considered important to its apoptotic activity. Here we report that the ferric cytochrome c/cardiolipin complex binds nitric oxide tightly through a multistep process in which the first step is the relatively slow displacement (5 s(-1)) from heme coordination of an intrinsic ligand that replaces methionine in the complex. Nanosecond photolysis of the nitrosyl adduct demonstrated that a fraction of the nitric oxide escapes from the heme pocket and subsequently recombines to the heme in second-order processes (k = 1.8 × 10(6) and 5.5 × 10(5) M(-1) s(-1)) that, under these conditions, were much faster than recombination of the intrinsic ligand with which they compete. Ultrafast (femtosecond) laser photolysis showed that the geminate recombination of nitric oxide to the heme occurred with time constants (τ = 22 and 72 ps) and that ~23% of the photolyzed nitric oxide escaped into the bulk phase. This high value for the escape fraction relative to other heme proteins indicates the open nature of the heme pocket in this complex. These results are summarized in a scheme and are discussed in terms of the possible modulation of the apoptotic activity of cytochrome c by nitric oxide.
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Affiliation(s)
- G Silkstone
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, C04 3SQ, UK.
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2
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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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3
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Yamamoto K, Ishikawa H, Takahashi S, Ishimori K, Morishima I, Nakajima H, Aono S. Binding of CO at the Pro2 side is crucial for the activation of CO-sensing transcriptional activator CooA. (1)H NMR spectroscopic studies. J Biol Chem 2001; 276:11473-6. [PMID: 11278259 DOI: 10.1074/jbc.c100047200] [Citation(s) in RCA: 45] [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
CooA is a heme-containing transcriptional activator that anaerobically binds to DNA at CO atmosphere. To obtain information on the conformational transition of CooA induced by CO binding to the heme, we assigned ring current-shifted (1)H NMR signals of CooA using two mutants whose axial ligands of the heme were replaced. In the absence of CO, the NMR spectral pattern of H77Y CooA, in which the axial histidine (His(77)) was replaced with tyrosine, was similar to that of wild-type CooA. In contrast, the spectra of CooADeltaN5, in which the NH(2) termini including the other axial ligand (Pro(2)) were deleted, were drastically modulated. We assigned three signals of wild-type CooA at -4.5, -3.6, and -2.8 ppm to delta(1)-, alpha-, and delta(2)-protons of Pro(2), respectively. The Pro(2) signals were undetectable in the upfield region of the spectrum of the CO-bound state, which confirms that CO displaces Pro(2). Interestingly, the Pro(2) signals were observed for CO-bound H77Y CooA, implying that CO binds to the trans position of Pro(2) in H77Y CooA. The abolished CO-dependent transcriptional activity of H77Y CooA is therefore the consequence of Pro(2) ligation. These observations are consistent with the view that the movement of the NH(2) terminus triggers the conformational transition to the DNA binding form.
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Affiliation(s)
- K Yamamoto
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
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4
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Zhou J, Fernández-Velasco JG, Malkin R. N-terminal mutants of chloroplast cytochrome f. Effect on redox reactions and growth in Chlamydomonas reinhardtII. J Biol Chem 1996; 271:6225-32. [PMID: 8626414 DOI: 10.1074/jbc.271.11.6225] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The N-terminal tyrosine of cytochrome f, which provides the sixth ligand to the heme group, has been changed by site-directed mutagenesis in Chlamydomonas reinhardtii to evaluate the role of this amino acid in assembly and function. The second and third residues, proline and valine, respectively, have also been mutated. Y1P is the only strain that did not grow photoautotrophically. The other strains show cytochrome b6f complex/photosystem I reaction center chlorophyll, photosystem I unit size and chlorophyll a+b/cell ratios comparable with wild-type cells. Rates of cytochrome f photooxidation in all strains were similar (t1/2 approximately = 300 microsec), whereas the rate of re-reduction sensitive to stigmatellin (at Eh = 0 mV, (where Eh is the ambient redox potential) for wild-type, Y1W, Y1F, Y1S, P2V, and V3P had a tl/2 of 3, 4, 5, 9, 40, and 2 ms, respectively. Rates of oxygen evolution by whole cells of P2V, Y1F, and Y1S were 67, 80, and 80% of wild-type rates, respectively. At low light intensity, all competent strains had the same growth rate whereas at saturating intensities, only P2V showed a significant inhibition. These results are considered in relation to structure-function relationships in the cytochrome f molecule.
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Affiliation(s)
- J Zhou
- Department of Plant Biology, University of California, Berkeley 94720-3102, USA
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5
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Affiliation(s)
- R C Prince
- Exxon Research and Engineering Co., Annandale, NJ 08801, USA
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6
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Ubbink M, Campos AP, Teixeira M, Hunt NI, Hill HA, Canters GW. Characterization of mutant Met100Lys of cytochrome c-550 from Thiobacillus versutus with lysine-histidine heme ligation. Biochemistry 1994; 33:10051-9. [PMID: 8060974 DOI: 10.1021/bi00199a032] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The heme iron in cytochrome c-550 from Thiobacillus versutus has a methionine and a histidine as axial ligands. In order to study the characteristics of a possible lysine-histidine ligation in a heme protein, the methionine has been replaced by a lysine. This residue acts as a ligand between pH 3 and 12. The midpoint potential of the mutant has shifted -329 mV compared to wild type, but apart from this shift the pH dependence of the midpoint potential is unchanged, suggesting that the large drop is caused by specific ligand effects and not by protein refolding. While the EPR spectrum of wild-type cytochrome c-550 shows one species with gz = 3.35, in the spectrum of the mutant two species occur with gz values of 3.53 and 3.30. The intensity ratio of both species depends on the presence of organic cosolvents. In the low frequency region (-4 to -1 ppm) of the 1H NMR spectrum of mutant ferrocytochrome c-550, four one-proton peaks replace the resonances of the ligand methionine side chain protons. Using two-dimensional NMR spectroscopy (COSY and NOESY), these protons and five others have been assigned to the lysine ligand. The spectroscopic results obtained for this mutant show similarities with those observed for the alkaline form of cytochrome c, supporting the Lys-His ligation proposed for this protein. The data are consistent with the evidence for amine ligation in cytochrome f: the EPR spectrum of M100K cytc-550 is similar to that of cytochrome f. However, the NMR spectra show significant differences.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Ubbink
- Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, The Netherlands
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7
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Martinez SE, Huang D, Szczepaniak A, Cramer WA, Smith JL. Crystal structure of chloroplast cytochrome f reveals a novel cytochrome fold and unexpected heme ligation. Structure 1994; 2:95-105. [PMID: 8081747 DOI: 10.1016/s0969-2126(00)00012-5] [Citation(s) in RCA: 286] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Cytochrome f is the high potential electron acceptor of the chloroplast cytochrome b6f complex, and is the electron donor to plastocyanin. The 285-residue cytochrome f subunit is anchored in the thylakoid membrane of the chloroplast by a single membrane-spanning segment near the carboxyl terminus. A soluble redox-active 252-residue lumen-side polypeptide with native spectroscopic and redox properties, missing the membrane anchor and carboxyl terminus, was purified from turnip chloroplasts for structural studies. RESULTS The crystal structure of cytochrome f, determined to 2.3 A resolution, has several unexpected features. The 252-residue polypeptide is organized into one large and one small domain. The larger heme-binding domain is strikingly different from known structures of other c-type cytochromes and has the same fold as the type III domain of the animal protein, fibronectin. Cytochrome f binds heme with an unprecedented axial heme iron ligand: the amino terminus of the polypeptide. CONCLUSION The first atomic structure of a subunit of either the cytochrome b6f complex or of the related cytochrome bc1 complex has been obtained. The structure of cytochrome f allows prediction of the approximate docking site of plastocyanin and should allow systematic studies of the mechanism of intra- and inter-protein electron transfer between the cytochrome heme and plastocyanin copper, which are approximately isopotential. The unprecedented axial heme iron ligand also provides information on the sequence of events (i.e. cleavage of signal peptide and ligation of heme) associated with translocation of the cytochrome across the membrane and its subsequent folding.
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Affiliation(s)
- S E Martinez
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392
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8
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Cramer WA, Martinez SE, Huang D, Tae GS, Everly RM, Heymann JB, Cheng RH, Baker TS, Smith JL. Structural aspects of the cytochrome b6f complex; structure of the lumen-side domain of cytochrome f. J Bioenerg Biomembr 1994; 26:31-47. [PMID: 8027021 PMCID: PMC4167668 DOI: 10.1007/bf00763218] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The following findings concerning the structure of the cytochrome b6f complex and its component polypeptides, cyt b6, subunit IV and cytochrome f subunit are discussed: (1) Comparison of the amino acid sequences of 13 and 16 cytochrome b6 and subunit IV polypeptides, respectively, led to (a) reconsideration of the helix lengths and probable interface regions, (b) identification of two likely surface-seeking helices in cyt b6 and one in SU IV, and (c) documentation of a high degree of sequence invariance compared to the mitochondrial cytochrome. The extent of identity is particularly high (88% for conserved and pseudoconserved residues) in the segments of cyt b6 predicted to be extrinsic on the n-side of the membrane. (2) The intramembrane attractive forces between trans-membrane helices that normally stabilize the packing of integral membrane proteins are relatively weak. (3) The complex isolated in dimeric form has been visualized, along with isolated monomer, by electron microscopy. The isolated dimer is much more active than the monomer, is the major form of the complex isolated and purified from chloroplasts, and is inferred to be a functional form in the membrane. (4) The isolated cyt b6f complex contains one molecule of chlorophyll a. (5) The structure of the 252 residue lumen-side domain of cytochrome f isolated from turnip chloroplasts has been solved by X-ray diffraction analysis to a resolution of 2.3 A.
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Affiliation(s)
- W A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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9
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Abstract
This paper provides an overview of the usefulness of the resonance Raman (RR) spectroscopy in the determination of the structural and electronic properties of heme(s) included in c-type cytochromes. It reviews the mode assignments presently available for heme c and includes recent RR data on the most important subclasses of c-type cytochromes. It also describes the effects of cytochrome c-oxidase and cytochrome c-reductase associations on the heme vibrational modes of the bound cytochrome c.
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Affiliation(s)
- A Desbois
- Département de Biologie Cellulaire et Moléculaire, Centre d'Etudes de Saclay, Gif-sur-Yvette, France
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10
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Lou BS, Hobbs JD, Chen YR, Yu L, Yu CA, Ondrias MR. Structural characterization of isolated mitochondrial cytochrome c1. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1144:403-10. [PMID: 8399285 DOI: 10.1016/0005-2728(93)90127-2] [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: 01/30/2023]
Abstract
Resonance Raman spectroscopy (RRS) has been employed to characterize cytochromes c1 isolated from bc1 complexes of beef heart mitochondria and Rhodopseudomonas sphaeroides. The data obtained in this study extend the physical characterization of cytochromes c1 and focus on the effects of the local protein environment on the heme active site. While the general characteristics of the cytochromes c1 are similar to those of smaller soluble cytochromes c, the behavior of several core-size and ligation-sensitive heme modes reveal that significant systematic differences exist between those species. These, most likely, result from changes in the heme axial-ligand interactions.
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Affiliation(s)
- B S Lou
- Department of Chemistry, University of New Mexico, Albuquerque 87131
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11
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Knaff DB. The cytochrome bc 1 complexes of photosynthetic purple bacteria. PHOTOSYNTHESIS RESEARCH 1993; 35:117-133. [PMID: 24318679 DOI: 10.1007/bf00014743] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/1992] [Accepted: 07/13/1992] [Indexed: 06/02/2023]
Abstract
Complete nucleotide sequences are now available for the pet (fbc) operons coding for the three electron carrying protein subunits of the cytochrome bc 1 complexes of four photosynthetic purple non-sulfur bacteria. It has been demonstrated that, although the complex from one of these bacteria may contain a fourth subunit, three subunit complexes appear to be fully functional. The ligands to the three hemes and the one [2Fe-2S] cluster in the complex have been identified and considerable progress has been made in mapping the two quinone-binding sites present in the complex, as well as the binding sites for quinone analog inhibitors. Hydropathy analyses and alkaline phosphatase fusion experiments have provided considerable insight into the likely folding pattern of the cytochrome b peptide of the complex and identification of the electrogenic steps associated with electron transport through the complex has allowed the orientation within the membrane of the electron-carrying groups of the complex to be modeled.
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Affiliation(s)
- D B Knaff
- Department of Chemistry and Biochemistry, Texas Tech University, 79409-1061, Lubbock, Texas, USA
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12
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Gray JC. Cytochrome f: Structure, function and biosynthesis. PHOTOSYNTHESIS RESEARCH 1992; 34:359-74. [PMID: 24408832 DOI: 10.1007/bf00029811] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/1992] [Accepted: 05/15/1992] [Indexed: 05/08/2023]
Abstract
Cytochrome f is an intrinsic membrane component of the cytochrome bf complex, transferring electrons from the Rieske FeS protein to plastocyanin in the thylakoid lumen. The protein is held in the thylakoid membrane by a single transmembrane span located near its C-terminus with a globular hydrophilic domain extending into the lumen. The globular domain of the turnip protein has recently been crystallised, offering the prospect of a detailed three-dimensional structure. Reaction with plastocyanin involves localised positive charges on cytochrome f interacting with the acidic patch on plastocyanin and electron transfer via the surface-exposed tyrosine residue (Tyr83) of plastocyanin. Apocytochrome f is encoded in the chloroplast genome and is synthesised with an N-terminal presequence which targets the protein to the thylakoid membrane. The synthesis of cytochrome f is coordinated with the synthesis of the other subunits of the cytochrome bf complex.
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Affiliation(s)
- J C Gray
- Department of Plant Sciences, University of Cambridge, Downing Street, CB2 3EA, Cambridge, UK
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13
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de Silva DGAH, Beoku-Betts D, Kyritsis P, Govindaraju K, Powls R, Tomkinson NP, Sykes AG. Protein–protein cross-reactions involving plastocyanin, cytochrome f and azurin: self-exchange rate constants and related studies with inorganic complexes. ACTA ACUST UNITED AC 1992. [DOI: 10.1039/dt9920002145] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Widger WR. The cloning and sequencing of Synechococcus sp. PCC 7002 petCA operon: Implications for the cytochrome c-553 binding domain of cytochrome f. PHOTOSYNTHESIS RESEARCH 1991; 30:71-84. [PMID: 24415256 DOI: 10.1007/bf00042005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/1990] [Accepted: 08/14/1991] [Indexed: 06/03/2023]
Abstract
The genes encoding the Rieske iron-sulfur protein and cytochrome f from a unicellular, naturally transformable, photoheterotrophic cyanobacterium, Synechococcus sp. PCC 7002, formerly Agmenellum quadruplicatum, have been isolated and sequenced. The two genes were found to be on a single operon, petCA.The Synechococcus sp. PCC 7002 iron-sulfur protein contains 181 amino acids, the conserved putative iron-binding domains CTHLGCV, residues 108-114, and CPCHGS, residues 128-133, no presequence and has a 73% sequence identity to the Nostoc PCC 7906 iron-sulfur protein. The 325 amino acid apocytochrome f sequence contains a 42 amino acid presequence, a CANCH heme binding domain, residues 20-24 from the presumed start of the mature protein, and a predicted hydrophobic membrane-spanning domain, residues 250-269. The mature cytochrome f sequence has a 71.5% sequence identity with Nostoc PCC 7906 cytochrome f and possesses a large (-14) negative charge and low calculated pI of 4.47 compared to higher plant chloroplast sequences. Nine separate domains showing differences in charged residues among cyanobacteria and plants have been identified and the possibility that these domains are involved in the ionic interactions with plastocyanin or cytochrome c-553 is discussed.
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Affiliation(s)
- W R Widger
- Department of Biochemical and Biophysical Sciences, University of Houston, 77204, Houston, TX, USA
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15
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Gross EL, Molnar S, Curtiss A, Reuter RA, Berg SP. The use of monoclonal antibodies to study the structure and function of cytochrome f. Arch Biochem Biophys 1991; 289:244-55. [PMID: 1716877 DOI: 10.1016/0003-9861(91)90468-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Monoclonal antibodies (MAbs) were prepared against native cytochrome f (cyt f) isolated from turnip leaves. The two MAbs obtained, designated MAb-JB2 and MAb-ED4, were Western blot positive to purified turnip cytochrome f and also reacted with inside-out (ISO) but not right-side-out (RSO) spinach thylakoid membranes. MAb-ED4 reacted with a covalent adduct formed by crosslinking cyt f and plastocyanin (PC), whereas MAb-JB2 did not. In contrast, MAb-JB2 reacted with the isolated cyt b6/f complex but MAb-ED4 did not. These results indicate that MAb-JB2 binds to cyt f at or near the PC binding site on f, whereas MAb-ED4 binds to a portion of cyt f which is not exposed in the cyt b6/f complex. The location of the epitopes in the primary sequence of cyt f was determined by trypsin hydrolysis, HPLC separation of tryptic peptides, and ELISA identification of the purified peptides. The molecular weights of the purified peptides, determined by gel exclusion chromatography, were found to be 5040 and 3130 Da for MAb-JB2 and MAb-ED4, respectively. Amino acid sequencing showed that the first eight amino acids of the MAb-ED4 positive peptide were L-D-Q-P-L-T-S-N. These results suggest that the 3130-Da peptide has 28 amino acids extending from Leu 223 to Arg 250. This peptide is located on the N-terminal (lumen) side of the postulated membrane-spanning sequence. The first eight amino acids of the MAb-JB2-positive peptide were N-I-L-V-I-G-P-V. This sequence and the peptide molecular weight indicate that the epitope for MAb-JB2 is located within a 44-amino acid peptide extending from Asn 111 to Arg 154.
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Affiliation(s)
- E L Gross
- Department of Biochemistry, Ohio State University, Columbus 43210
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16
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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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17
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Mayes SR, Barber J. Primary structure of the psbN-psbH-petC-petA gene cluster of the cyanobacterium Synechocystis PCC 6803. PLANT MOLECULAR BIOLOGY 1991; 17:289-293. [PMID: 1907512 DOI: 10.1007/bf00039508] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- S R Mayes
- Wolfson Laboratories, Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK
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18
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Majewski C, Trebst A. The pet genes of Rhodospirillum rubrum: cloning and sequencing of the genes for the cytochrome bc1-complex. MOLECULAR & GENERAL GENETICS : MGG 1990; 224:373-82. [PMID: 2176269 DOI: 10.1007/bf00262431] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A cytochrome bc1-complex of Rs. rubrum was isolated and the three subunits were purified to homogeneity. The N-terminal amino acid sequence of the purified subunits was determined by automatic Edman degradation. The pet genes of Rhodospirillum rubrum coding for the three subunits of the cytochrome bc1-complex were isolated from a genomic library of Rs. rubrum using oligonucleotides specific for conserved regions of the subunits from other organisms and a heterologous probe derived from the genes for the complex of Rb. capsulatus. The complete nucleotide sequence of a 5500 bp SalI/SphI fragment is described which includes the pet genes and three additional unidentified open reading frames. The N-terminal amino acid sequence of the isolated subunits was used for the identification of the three genes. The genes encoding the subunits are organized as follows: Rieske protein, cytochrome b, cytochrome c1. Comparison of the N-terminal protein sequences with the protein sequences deduced from the nucleotide sequence showed that only cytochrome c1 is processed during transport and assembly of the three subunits of the complex. Only the N-terminal methionine of the Rieske protein is cleaved off. The similarity of the deduced amino acid sequence of the three subunits to the corresponding subunits of other organisms is described and implications for structural features of the subunits are discussed.
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Affiliation(s)
- C Majewski
- Lehrstuhl Biochemie der Pflanzen, Ruhr-Universität, Bochum, FRG
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19
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Weitzel F, Ursini F, Wendel A. Phospholipid hydroperoxide glutathione peroxidase in various mouse organs during selenium deficiency and repletion. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1036:88-94. [PMID: 2223835 DOI: 10.1016/0304-4165(90)90018-r] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
An assay for the determination of the newly discovered selenoenzyme, phospholipid hydroperoxide glutathione peroxidase (PH-GPx) in biological material is described. Dietary selenium deficiency and repletion was used as a tool in order to modify this enzyme activity in various mouse organs and to compare it to the activity of the 'classical' selenium-dependent glutathione peroxidase (GPx) (EC 1.11.1.9). A semipurified diet containing less than 12 ppb Se was used for depletion. Controls received this diet supplemented with 500 ppb Se in the form of Na2SeO3. The results showed that a rapid loss of GPx activity occurred in liver, kidney and lungs of selenium-deficient mice which reached undetectable levels within 130 days. In the heart, about 24% of control GPx activity was still present. In contrast, PH-GPx activity was more slowly depleted by Se deficiency and resulted in residual activities ranging from 30 to 70% in the different organs even after 250 days of depletion. In repletion experiments with a single application of 10 or 500 micrograms/kg Se, only the high dose restored either enzyme activity. The data demonstrate that the need for selenium of the two glutathione peroxidases is different. A markedly distinct organ distribution of both enzymes suggests that the heart may be the organ more sensitive to oxidative stress.
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Affiliation(s)
- F Weitzel
- Faculty of Biology, University of Konstanz, F.R.G
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20
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Simpkin D, Palmer G, Devlin FJ, McKenna MC, Jensen GM, Stephens PJ. The axial ligands of heme in cytochromes: a near-infrared magnetic circular dichroism study of yeast cytochromes c, c1, and b and spinach cytochrome f. Biochemistry 1989; 28:8033-9. [PMID: 2557894 DOI: 10.1021/bi00446a010] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Room temperature near-infrared magnetic circular dichroism and low-temperature electron paramagnetic resonance measurements have been used to characterize the ligands of the heme iron in mitochondrial cytochromes c, c1, and b and in cytochrome f of the photosynthetic electron transport chain. The MCD data show that methionine is the sixth ligand of the heme of oxidized yeast cytochrome c1; the identify of this residue is inferred to be the single conserved methionine identified from a partial alignment of the available cytochrome c1 amino acid sequences. A different residue, which is most likely lysine, is the sixth heme ligand in oxidized spinach cytochrome f. The data for oxidized yeast cytochrome b are consistent with bis-histidine coordination of both hemes although the possibility that one of the hemes is ligated by histidine and lysine cannot be rigorously excluded. The neutral and alkaline forms of oxidized yeast cytochrome c have spectroscopic properties very similar to those of the horse heart proteins, and thus, by analogy, the sixth ligands are methionine and lysine, respectively.
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Affiliation(s)
- D Simpkin
- Department of Biochemistry, Rice University, Houston, Texas 77251
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Morand LZ, Frame MK, Colvert KK, Johnson DA, Krogmann DW, Davis DJ. Plastocyanin cytochrome f interaction. Biochemistry 1989; 28:8039-47. [PMID: 2605172 DOI: 10.1021/bi00446a011] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Spinach plastocyanin and turnip cytochrome f have been covalently linked by using a water-soluble carbodiimide to yield an adduct of the two proteins. The redox potential of cytochrome f in the adduct was shifted by -20 mV relative to that of free cytochrome f, while the redox potential of plastocyanin in the adduct was the same as that of free plastocyanin. Solvent perturbation studies showed the degree of heme exposure in the adduct to be less than in free cytochrome f, indicating that plastocyanin was linked in such a way as to bury the exposed heme edge. Small changes were also observed when the resonance Raman spectrum of the adduct was compared to that of free cytochrome f. The adduct was incapable of interacting with or donating electrons to photosystem I. Peptide mapping and sequencing studies revealed two sites of linkage between the two proteins. In one site of linkage, Asp-44 of plastocyanin is covalently linked to Lys-187 of cytochrome f. This represents the first identification of a group on cytochrome f that is involved in the interaction with plastocyanin. The other site of linkage involves Glu-59 and/or Glu-60 of plastocyanin to as yet unidentified amino groups on cytochrome f. Euglena cytochrome c-552 could also be covalently linked to turnip cytochrome f, although with a lower efficiency than spinach plastocyanin. In contrast, a variety of cyanobacterial cytochrome c-553's and a cyanobacterial plastocyanin could not be covalently linked to turnip cytochrome f.
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Affiliation(s)
- L Z Morand
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701
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