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Heering HA. Analysis of protein film voltammograms as Michaelis–Menten saturation curves yield the electron cooperativity number for deconvolution. Bioelectrochemistry 2012; 87:58-64. [DOI: 10.1016/j.bioelechem.2011.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 12/14/2011] [Accepted: 12/17/2011] [Indexed: 12/28/2022]
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52
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Wächtler M, Guthmuller J, González L, Dietzek B. Analysis and characterization of coordination compounds by resonance Raman spectroscopy. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.02.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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53
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Manrique C, Lastra G, Habibi J, Pulakat L, Schneider R, Durante W, Tilmon R, Rehmer J, Hayden MR, Ferrario CM, Whaley-Connell A, Sowers JR. Nebivolol improves insulin sensitivity in the TGR(Ren2)27 rat. Metabolism 2011; 60:1757-66. [PMID: 21640361 PMCID: PMC3170670 DOI: 10.1016/j.metabol.2011.04.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 04/13/2011] [Accepted: 04/16/2011] [Indexed: 11/23/2022]
Abstract
Hypertension is often associated with increased oxidative stress and systemic insulin resistance. Use of β-adrenergic receptor blockers in hypertension is limited because of potential negative influence on insulin sensitivity and glucose homeostasis. We sought to determine the impact of nebivolol, a selective vasodilatory β₁-adrenergic blocker, on whole-body insulin sensitivity, skeletal muscle oxidative stress, insulin signaling, and glucose transport in the transgenic TG(mRen2)27 rat (Ren2). This rodent model manifests increased tissue renin angiotensin expression, excess oxidative stress, and whole-body insulin resistance. Young (age, 6-9 weeks) Ren2 and age-matched Sprague-Dawley control rats were treated with nebivolol 10 mg/(kg d) or placebo for 21 days. Basal measurements were obtained for glucose and insulin to calculate the homeostasis model assessment. In addition, insulin metabolic signaling, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, reactive oxygen species, and ultrastructural changes as evaluated by transmission electron microscopy were examined ex vivo in skeletal muscle tissue. The Ren2 rat demonstrated systemic insulin resistance as examined by the homeostasis model assessment, along with impaired insulin metabolic signaling in skeletal muscle. This was associated with increased oxidative stress and mitochondrial remodeling. Treatment with nebivolol was associated with improvement in insulin resistance and decreased NADPH oxidase activity/levels of reactive oxygen species in skeletal muscle tissue. Nebivolol treatment for 3 weeks reduces NADPH oxidase activity and improves systemic insulin resistance in concert with reduced oxidative stress in skeletal muscle in a young rodent model of hypertension, insulin resistance, and enhanced tissue RAS expression.
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Affiliation(s)
- Camila Manrique
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
| | - Guido Lastra
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
| | - Javad Habibi
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
- Research Service, Harry S. Truman Veterans Affairs Medical Center, Columbia, Missouri, 65201
| | - Lakshmi Pulakat
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
| | - Rebecca Schneider
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
- Research Service, Harry S. Truman Veterans Affairs Medical Center, Columbia, Missouri, 65201
| | - William Durante
- Medical Pharmacology and Physiology, University of Missouri-Columbia School of Medicine
| | - Roger Tilmon
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
| | - Jenna Rehmer
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
| | - Melvin R Hayden
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
| | - Carlos M. Ferrario
- Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina, 27157
| | - Adam Whaley-Connell
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
- Research Service, Harry S. Truman Veterans Affairs Medical Center, Columbia, Missouri, 65201
| | - James R. Sowers
- Diabetes Cardiovascular Center of Excellence, University of Missouri-Columbia School of Medicine
- Medical Pharmacology and Physiology, University of Missouri-Columbia School of Medicine
- Research Service, Harry S. Truman Veterans Affairs Medical Center, Columbia, Missouri, 65201
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Attallah CV, Welchen E, Martin AP, Spinelli SV, Bonnard G, Palatnik JF, Gonzalez DH. Plants contain two SCO proteins that are differentially involved in cytochrome c oxidase function and copper and redox homeostasis. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4281-94. [PMID: 21543521 DOI: 10.1093/jxb/err138] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two Arabidopsis thaliana genes (HCC1 and HCC2), resulting from a duplication that took place before the emergence of flowering plants, encode proteins with homology to the SCO proteins involved in copper insertion during cytochrome c oxidase (COX) assembly in other organisms. Heterozygote HCC1 mutant plants produce 25% abnormal seeds with defective embryos arrested at the heart or torpedo stage. These embryos lack COX activity, suggesting that the requirement of HCC1 during the early stages of plant development is related with its COX assembly function. Homozygote HCC2 mutant plants develop normally and do not show changes in COX2 levels. These plants display increased sensitivity of root growth to increased copper and a higher expression of miR398 and other genes that respond to copper limitation, in spite of the fact that they have a higher copper content than the wild type. HCC2 mutant plants also show increased expression of stress-responsive genes. The results suggest that HCC1 is the protein involved in COX biogenesis and that HCC2, that lacks the cysteines and histidine putatively involved in copper binding, functions in copper sensing and redox homeostasis. In addition, plants that overexpress HCC1 have an altered response of root elongation to changes in copper in the growth medium and increased expression of two low-copper-responsive genes, suggesting that HCC1 may also have a role in copper homeostasis.
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Affiliation(s)
- Carolina V Attallah
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, CC 242 Paraje El Pozo, 3000 Santa Fe, Argentina
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Shevchenko UG, Berdinskii VL. Enzymic processes as a mechanism of biological magnetoreception. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2011. [DOI: 10.1134/s1990793111020230] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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56
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Banci L, Bertini I, Cavallaro G, Ciofi-Baffoni S. Seeking the determinants of the elusive functions of Sco proteins. FEBS J 2011; 278:2244-62. [DOI: 10.1111/j.1742-4658.2011.08141.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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57
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Varanasi L, Hosler J. Alternative initial proton acceptors for the D pathway of Rhodobacter sphaeroides cytochrome c oxidase. Biochemistry 2011; 50:2820-8. [PMID: 21344856 DOI: 10.1021/bi102002v] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To characterize protein structures that control proton uptake, we assayed forms of cytochrome c oxidase (CcO) containing a carboxyl or a thiol group in line with the initial, internal waters of the D pathway for proton transfer in the presence and absence of subunit III. Subunit III provides approximately half of the protein surrounding the entry region of the D pathway. The N139D/D132N mutant contains a carboxyl group 6 Å within the D pathway and lacks the normal, surface-exposed proton acceptor, Asp-132. With subunit III, the steady-state activity of this mutant is slow, but once subunit III is removed, its activity is the same as that of wild-type CcO lacking subunit III (∼1800 H+/s). Thus, a carboxyl group∼25% within the pathway enhances proton uptake even though the carboxyl has no direct contact with bulk solvent. Protons from solvent apparently move to internal Asp-139 through a short file of waters, normally blocked by subunit III. Cys-139 also supports rapid steady-state proton uptake, demonstrating that an anion other than a carboxyl can attract and transfer protons into the D pathway. When both Asp-132 and Asp/Cys-139 are present, the removal of subunit III increases CcO activity to rates greater than that of normal CcO because of simultaneous proton uptake by two initial acceptors. The results show how the environment of the initial proton acceptor for the D pathway in these CcO forms dictates the pH range of CcO activity, with implications for the function of Asp-132, the normal proton acceptor.
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Affiliation(s)
- Lakshman Varanasi
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, United States
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58
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Chen HK, Ji ZS, Dodson SE, Miranda RD, Rosenblum CI, Reynolds IJ, Freedman SB, Weisgraber KH, Huang Y, Mahley RW. Apolipoprotein E4 domain interaction mediates detrimental effects on mitochondria and is a potential therapeutic target for Alzheimer disease. J Biol Chem 2010; 286:5215-21. [PMID: 21118811 DOI: 10.1074/jbc.m110.151084] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Apolipoprotein (apo) E4 is the major genetic risk factor for late-onset Alzheimer disease (AD). ApoE4 assumes a pathological conformation through an intramolecular interaction mediated by Arg-61 in the amino-terminal domain and Glu-255 in the carboxyl-terminal domain, referred to as apoE4 domain interaction. Because AD is associated with mitochondrial dysfunction, we examined the effect of apoE4 domain interaction on mitochondrial respiratory function. Steady-state amounts of mitochondrial respiratory complexes were examined in neurons cultured from brain cortices of neuron-specific enolase promoter-driven apoE3 (NSE-apoE3) or apoE4 (NSE-apoE4) transgenic mice. All subunits of mitochondrial respiratory complexes assessed were significantly lower in NSE-apoE4 neurons compared with NSE-apoE3 neurons. However, no significant differences in levels of mitochondrial complexes were detected between astrocytes expressing different apoE isoforms driven by the glial fibrillary acidic protein promoter, leading to our conclusion that the effect of apoE4 is neuron specific. In neuroblastoma Neuro-2A (N2A) cells, apoE4 expression reduced the levels of mitochondrial respiratory complexes I, IV, and V. Complex IV enzymatic activity was also decreased, lowering mitochondrial respiratory capacity. Mutant apoE4 (apoE4-Thr-61) lacking domain interaction did not induce mitochondrial dysfunction in N2A cells, indicating that the effect is specific to apoE4-expressing cells and dependent on domain interaction. Consistent with this finding, treatment of apoE4-expressing N2A cells with a small molecule that disrupts apoE4 domain interaction restored mitochondrial respiratory complex IV levels. These results suggest that pharmacological intervention with small molecules that disrupt apoE4 domain interaction is a potential therapeutic approach for apoE4-carrying AD subjects.
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Affiliation(s)
- Hung-Kai Chen
- Gladstone Center for Translational Research, San Francisco, California 94158, USA
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59
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The putative assembly factor CcoH is stably associated with the cbb3-type cytochrome oxidase. J Bacteriol 2010; 192:6378-89. [PMID: 20952576 DOI: 10.1128/jb.00988-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytochrome oxidases are perfect model substrates for analyzing the assembly of multisubunit complexes because the need for cofactor incorporation adds an additional level of complexity to their assembly. cbb(3)-type cytochrome c oxidases (cbb(3)-Cox) consist of the catalytic subunit CcoN, the membrane-bound c-type cytochrome subunits CcoO and CcoP, and the CcoQ subunit, which is required for cbb(3)-Cox stability. Biogenesis of cbb(3)-Cox proceeds via CcoQP and CcoNO subcomplexes, which assemble into the active cbb(3)-Cox. Most bacteria expressing cbb(3)-Cox also contain the ccoGHIS genes, which encode putative cbb(3)-Cox assembly factors. Their exact function, however, has remained unknown. Here we analyzed the role of CcoH in cbb(3)-Cox assembly and showed that CcoH is a single spanning-membrane protein with an N-terminus-out-C-terminus-in (N(out)-C(in)) topology. In its absence, neither the fully assembled cbb(3)-Cox nor the CcoQP or CcoNO subcomplex was detectable. By chemical cross-linking, we demonstrated that CcoH binds primarily via its transmembrane domain to the CcoP subunit of cbb(3)-Cox. A second hydrophobic stretch, which is located at the C terminus of CcoH, appears not to be required for contacting CcoP, but deleting it prevents the formation of the active cbb(3)-Cox. This suggests that the second hydrophobic domain is required for merging the CcoNO and CcoPQ subcomplexes into the active cbb(3)-Cox. Surprisingly, CcoH does not seem to interact only transiently with the cbb(3)-Cox but appears to stay tightly associated with the active, fully assembled complex. Thus, CcoH behaves more like a bona fide subunit of the cbb(3)-Cox than an assembly factor per se.
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Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster. Biochem Biophys Res Commun 2010; 401:64-8. [PMID: 20833144 DOI: 10.1016/j.bbrc.2010.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 09/06/2010] [Indexed: 11/21/2022]
Abstract
The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H₂O₂ generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.
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61
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Thompson AK, Smith D, Gray J, Carr HS, Liu A, Winge DR, Hosler JP. Mutagenic analysis of Cox11 of Rhodobacter sphaeroides: insights into the assembly of Cu(B) of cytochrome c oxidase. Biochemistry 2010; 49:5651-61. [PMID: 20524628 DOI: 10.1021/bi1003876] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Cu(I) chaperone Cox11 is required for the insertion of Cu(B) into cytochrome c oxidase (CcO) of mitochondria and many bacteria, including Rhodobacter sphaeroides. Exploration of the copper binding stoichiometry of R. sphaeroides Cox11 led to the finding that an apparent tetramer of both mitochondrial and bacterial Cox11 binds more copper than the sum of the dimers, providing another example of the flexibility of copper binding by Cu(I)-S clusters. Site-directed mutagenesis has been used to identify components of Cox11 that are not required for copper binding but are absolutely required for the assembly of Cu(B), including conserved Cys-35 and Lys-123. In contrast to earlier proposals, Cys-35 is not required for dimerization of Cox11 or for copper binding. These findings, and the location of Cys-35 at the C-terminus of the predicted transmembrane helix and thereby close to the surface of the membrane, allow a proposal that Cys-35 is involved in the transfer of copper from the Cu(I) cluster of Cox11 to the Cu(B) ligands His-333 and His-334 during the folding of CcO subunit I. Lys-123 is located near the Cu(I) cluster of Cox11, in an area otherwise devoid of charged residues. From the analysis of several Cox11 mutants, including K123E, -L, and -R, we conclude that a previous proposal that Lys-123 provides charge balance for the stabilization of the Cu(I) cluster is unlikely to account for its absolute requirement for Cox11 function. Rather, consideration of the properties of Lys-123 and the apparent specificity of Cox11 suggest that Lys-123 plays a role in the interaction of Cox11 with its target.
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Affiliation(s)
- Audie K Thompson
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
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62
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Babich PS, Tsymbalenko NV, Klotchenko SA, Platonova NA, Masalova OO, Zatulovski EA, Shavlovskii MM, Sapronov NS, Puchkova LV. Effect of a Deficiency of Ceruloplasmin Copper in Blood Plasma on Copper Metabolism in the Brain. Bull Exp Biol Med 2010; 148:592-7. [DOI: 10.1007/s10517-010-0772-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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63
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Iaffaldano N, Rosato MP, Paventi G, Pizzuto R, Gambacorta M, Manchisi A, Passarella S. The irradiation of rabbit sperm cells with He-Ne laser prevents their in vitro liquid storage dependent damage. Anim Reprod Sci 2009; 119:123-9. [PMID: 19932573 DOI: 10.1016/j.anireprosci.2009.10.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 10/01/2009] [Accepted: 10/06/2009] [Indexed: 10/20/2022]
Abstract
The aim of the study was to investigate the effects of different energy doses of helium-neon (He-Ne) laser irradiation on both mitochondrial bioenergetics functions and functional quality of rabbit spermatozoa during 48 h of in vitro liquid storage at 15 degrees C. 11 rabbit semen pools were each divided into four aliquots: three of them were irradiated with He-Ne laser with different energy doses (3.96, 6.12 and 9.00 J/cm(2)) being the last control kept under the same experimental conditions without irradiation. Sperm motility, viability and acrosome integrity were monitored together with cytochrome c oxidase (COX) activity and the cell energy charge (EC) at 0, 24 and 48 h of storage. Irradiated samples stored for 24 and 48 h better maintained motility (P < 0.01), acrosome integrity (P < 0.01) and viability (P < 0.05) with respect to the control, particularly with the energy dose of 6.12 J/cm(2) that showed the most intense biostimulative effect. COX activity and EC were immediately increased by irradiation particularly in the treatments 6.12 and 9.00 J/cm(2) (P < 0.05), that maintained their levels higher with respect to the control after 48 h of storage (P < 0.01). COX activity of rabbit sperm cells was positively correlated with EC (P < 0.05), viability (P < 0.01) and acrosome integrity (P < 0.05) parameters. These results indicate that the effects of He-Ne laser irradiation on sperm cells are mediated through the stimulation of the sperm mitochondrial respiratory chain and that this effect plays a significant role in the augmentation of the rabbit sperm cells' capability to survive during liquid storage conditions.
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Affiliation(s)
- Nicolaia Iaffaldano
- Department of Animal, Vegetable and Environmental Sciences, University of Molise, 86100 Campobasso, Italy.
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64
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Gross J, Bhattacharya D. Mitochondrial and plastid evolution in eukaryotes: an outsiders' perspective. Nat Rev Genet 2009; 10:495-505. [PMID: 19506574 DOI: 10.1038/nrg2610] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The eukaryotic organelles mitochondrion and plastid originated from eubacterial endosymbionts. Here we propose that, in both cases, prokaryote-to-organelle conversion was driven by the internalization of host-encoded factors progressing from the outer membrane of the endosymbionts towards the intermembrane space, inner membrane and finally the organelle interior. This was made possible by an outside-to-inside establishment in the endosymbionts of host-controlled protein-sorting components, which enabled the gradual integration of organelle functions into the nuclear genome. Such a convergent trajectory for mitochondrion and plastid establishment suggests a novel paradigm for organelle evolution that affects theories of eukaryogenesis.
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Affiliation(s)
- Jeferson Gross
- Department of Biology, Roy J. Carver Center for Comparative Genomics, University of Iowa, 446 Biology Building, Iowa City, Iowa 52242, USA
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65
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Chakrabarti R, Shepardson S, Karmakar M, Trdan R, Walker J, Shandilya R, Stewart D, Vijayaraghavan S, Hoeh W. Extra-mitochondrial localization and likely reproductive function of a female-transmitted cytochrome c oxidase subunit II protein. Dev Growth Differ 2009; 51:511-9. [PMID: 19469787 DOI: 10.1111/j.1440-169x.2009.01113.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Our previous study documented a reproductive function for the male-transmitted mitochondrial DNA (mtDNA)-encoded cytochrome c oxidase subunit II (MCOX2) protein in a unionoid bivalve. Here, immunoblotting, immunohistochemistry and immunoelectron microscopy analyses demonstrate that the female-transmitted protein (FCOX2) is: (i) expressed in both male and female gonads; (ii) maximally expressed in ovaries just prior to the time of the annual fertilization event; (iii) displayed in the cytoplasm and more strongly in the plasma membrane (microvilli), vitelline matrix and vitelline envelope of mature ovarian eggs; and (iv) strongly localized to the vitelline matrix of some eggs just prior to fertilization. These findings represent evidence for the extra-mitochondrial localization of an mtDNA-encoded gene product and are consistent with multifunctionality for FCOX2 in eggs.
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Affiliation(s)
- Rumela Chakrabarti
- Department of Biochemistry, State University of New York, Buffalo, New York 14214, USA.
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66
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Comelli RN, Viola IL, Gonzalez DH. Characterization of promoter elements required for expression and induction by sucrose of the Arabidopsis COX5b-1 nuclear gene, encoding the zinc-binding subunit of cytochrome c oxidase. PLANT MOLECULAR BIOLOGY 2009; 69:729-743. [PMID: 19125337 DOI: 10.1007/s11103-008-9451-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 12/17/2008] [Indexed: 05/27/2023]
Abstract
Arabidopsis COX5b-1 encodes an isoform of the zinc binding subunit 5b of mitochondrial cytochrome c oxidase. A promoter region required for expression and induction by sucrose of this gene was analyzed using plants stably transformed with mutagenized promoter fragments fused to the gus reporter gene. Promoter dependent expression is absolutely dependent on a G-box present at -228 from the translation start site. This element interacts in vitro and in vivo with transcription factors from the bZip family, preferentially with the abscisic acid-responsive element binding factor AREB2/ABF4. A region located upstream of the G-box (-333/-259) contains elements with the core sequence ATCATT and distalB-like sequences (CCACTTG) that are required for expression in vegetative tissues. These sequences bind different sets of proteins present in plant nuclear extracts and participate in induction by sucrose (ATCATT) and abscisic acid (distalB) of the COX5b-1 promoter. We propose that the COX5b-1 promoter has acquired novel regulatory mechanisms during evolution after gene duplication. These novel mechanisms have allowed the diversification of expression patterns, but also the conservation of some responses that, as induction by sucrose, are shared by COX5b-1 and other genes encoding components of the mitochondrial respiratory chain. Conservation of these responses may be a pre-requisite for the successful incorporation of new regulatory elements in this class of genes.
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Affiliation(s)
- Raúl N Comelli
- Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, CC 242 Paraje El Pozo, 3000 Santa Fe, Argentina
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Richter OMH, Ludwig B. Electron transfer and energy transduction in the terminal part of the respiratory chain - lessons from bacterial model systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:626-34. [PMID: 19268423 DOI: 10.1016/j.bbabio.2009.02.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 02/13/2009] [Accepted: 02/16/2009] [Indexed: 11/18/2022]
Abstract
This review focuses on the terminal part of the respiratory chain where, macroscopically speaking, electron transfer (ET) switches from the two-electron donor, ubiquinol, to the single-electron carrier, cytochrome c, to finally reduce the four-electron acceptor dioxygen. With 3-D structures of prominent representatives of such multi-subunit membrane complexes known for some time, this section of the ET chain still leaves a number of key questions unanswered. The two relevant enzymes, ubiquinol:cytochrome c oxidoreductase and cytochrome c oxidase, appear as rather diverse modules, differing largely in their design for substrate interaction, internal ET, and moreover, in their mechanisms of energy transduction. While the canonical mitochondrial complexes have been investigated for almost five decades, the corresponding bacterial enzymes have been established only recently as attractive model systems to address basic reactions in ET and energy transduction. Lacking the intricate coding background and mitochondrial assembly pathways, bacterial respiratory enzymes typically offer a much simpler subunit composition, while maintaining all fundamental functions established for their complex "relatives". Moreover, related issues ranging from primary steps in cofactor insertion to supramolecular architecture of ET complexes, can also be favourably addressed in prokaryotic systems to hone our views on prototypic structures and mechanisms common to all family members.
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Affiliation(s)
- Oliver-Matthias H Richter
- Institute of Biochemistry, Molecular Genetics, Biozentrum Goethe University, Max-von-Laue-Str. 9, D 60438 Frankfurt, Germany
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Liu B, Chen Y, Doukov T, Soltis SM, Stout CD, Fee JA. Combined microspectrophotometric and crystallographic examination of chemically reduced and X-ray radiation-reduced forms of cytochrome ba3 oxidase from Thermus thermophilus: structure of the reduced form of the enzyme. Biochemistry 2009; 48:820-6. [PMID: 19140675 DOI: 10.1021/bi801759a] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three paths for obtaining crystals of reduced (II-E4Q/I-K258R) cytochrome ba(3) are described, and the structures of these are reported at approximately 2.8-3.0 A resolution. Microspectrophotometry of single crystals of Thermus ba(3) oxidase at 100 K was used to show that crystals of the oxidized enzyme are reduced in an intense X-ray (beam line 7-1 at the Stanford Synchrotron Radiation Laboratory), being nearly complete in 1 min. The previously reported structures of ba(3) (Protein Data Bank entries 1EHK and 1XME ), having a crystallographically detectable water between the Cu(B) and Fe(a3) metals of the dinuclear center, actually represent the X-ray radiation-reduced enzyme. Dithionite-reduced crystals or crystals formed from dithionite-reduced enzyme revealed the absence of the above-mentioned water and an increase in the Cu(B)-Fe(a3) distance of approximately 0.3 A. The new structures are discussed in terms of enzyme function. An unexpected optical absorption envelope at approximately 590 nm is also reported. This spectral feature is tentatively thought to arise from a five-coordinate, low-spin, ferrous heme a(3) that is trapped in the frozen crystals.
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Affiliation(s)
- Bin Liu
- Department of Molecular Biology, The Scripps Research Institute, MB-8, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Tachtsidis I, Tisdall MM, Leung TS, Pritchard C, Cooper CE, Smith M, Elwell CE. Relationship Between Brain Tissue Haemodynamics, Oxygenation And Metabolism In The Healthy Human Adult Brain During Hyperoxia And Hypercapnea. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 645:315-20. [DOI: 10.1007/978-0-387-85998-9_47] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Fee JA, Case DA, Noodleman L. Toward a chemical mechanism of proton pumping by the B-type cytochrome c oxidases: application of density functional theory to cytochrome ba3 of Thermus thermophilus. J Am Chem Soc 2008; 130:15002-21. [PMID: 18928258 DOI: 10.1021/ja803112w] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mechanism for proton pumping by the B-type cytochrome c oxidases is presented in which one proton is pumped in conjunction with the weakly exergonic, two-electron reduction of Fe-bound O 2 to the Fe-Cu bridging peroxodianion and three protons are pumped in conjunction with the highly exergonic, two-electron reduction of Fe(III)- (-)O-O (-)-Cu(II) to form water and the active oxidized enzyme, Fe(III)- (-)OH,Cu(II). The scheme is based on the active-site structure of cytochrome ba 3 from Thermus thermophilus, which is considered to be both necessary and sufficient for coupled O 2 reduction and proton pumping when appropriate gates are in place (not included in the model). Fourteen detailed structures obtained from density functional theory (DFT) geometry optimization are presented that are reasonably thought to occur during the four-electron reduction of O 2. Each proton-pumping step takes place when a proton resides on the imidazole ring of I-His376 and the large active-site cluster has a net charge of +1 due to an uncompensated, positive charge formally associated with Cu B. Four types of DFT were applied to determine the energy of each intermediate, and standard thermochemical approaches were used to obtain the reaction free energies for each step in the catalytic cycle. This application of DFT generally conforms with previously suggested criteria for a valid model (Siegbahn, P. E. M.; Blomberg, M. A. R. Chem. Rev. 2000, 100, 421-437) and shows how the chemistry of O 2 reduction in the heme a 3 -Cu B dinuclear center can be harnessed to generate an electrochemical proton gradient across the lipid bilayer.
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Affiliation(s)
- James A Fee
- The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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72
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Tisdall MM, Tachtsidis I, Leung TS, Elwell CE, Smith M. Increase in cerebral aerobic metabolism by normobaric hyperoxia after traumatic brain injury. J Neurosurg 2008; 109:424-32. [PMID: 18759572 DOI: 10.3171/jns/2008/109/9/0424] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Traumatic brain injury (TBI) is associated with depressed aerobic metabolism and mitochondrial dysfunction. Normobaric hyperoxia (NBH) has been suggested as a treatment for TBI, but studies in humans have produced equivocal results. In this study the authors used brain tissue O(2) tension measurement, cerebral microdialysis, and near-infrared spectroscopy to study the effects of NBH after TBI. They investigated the effects on cellular and mitochondrial redox states measured by the brain tissue lactate/pyruvate ratio (LPR) and the change in oxidized cytochrome c oxidase (CCO) concentration, respectively. METHODS The authors studied 8 adults with TBI within the first 48 hours postinjury. Inspired oxygen percentage at normobaric pressure was increased from baseline to 60% for 60 minutes and then to 100% for 60 minutes before being returned to baseline for 30 minutes. RESULTS The results are presented as the median with the interquartile range in parentheses. During the 100% inspired oxygen percentage phase, brain tissue O2 tension increased by 7.2 kPa (range 4.5-9.6 kPa) (p < 0.0001), microdialysate lactate concentration decreased by 0.26 mmol/L (range 0.0-0.45 mmol/L) (p = 0.01), microdialysate LPR decreased by 1.6 (range 1.0-2.3) (p = 0.02), and change in oxidized CCO concentration increased by 0.21 mumol/L (0.13-0.38 micromol/L) (p = 0.0003). There were no significant changes in intracranial pressure or arterial or microdialysate glucose concentration. The change in oxidized CCO concentration correlated with changes in brain tissue O(2) tension (r(s)= 0.57, p = 0.005) and in LPR (r(s)= -0.53, p = 0.006). CONCLUSIONS The authors have demonstrated oxidation in cerebral cellular and mitochondrial redox states during NBH in adults with TBI. These findings are consistent with increased aerobic metabolism and suggest that NBH has the potential to improve outcome after TBI. Further studies are warranted.
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Affiliation(s)
- Martin M Tisdall
- Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery, UK
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73
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Greiner P, Hannappel A, Werner C, Ludwig B. Biogenesis of cytochrome c oxidase — in vitro approaches to study cofactor insertion into a bacterial subunit I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:904-11. [DOI: 10.1016/j.bbabio.2008.04.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 03/25/2008] [Accepted: 04/02/2008] [Indexed: 11/24/2022]
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74
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Stability of the cbb3-type cytochrome oxidase requires specific CcoQ-CcoP interactions. J Bacteriol 2008; 190:5576-86. [PMID: 18556791 DOI: 10.1128/jb.00534-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytochrome cbb(3)-type oxidases are members of the heme copper oxidase superfamily and are composed of four subunits. CcoN contains the heme b-Cu(B) binuclear center where oxygen is reduced, while CcoP and CcoO are membrane-bound c-type cytochromes thought to channel electrons from the donor cytochrome into the binuclear center. Like many other bacterial members of this superfamily, the cytochrome cbb(3)-type oxidase contains a fourth, non-cofactor-containing subunit, which is termed CcoQ. In the present study, we analyzed the role of CcoQ on the stability and activity of Rhodobacter capsulatus cbb(3)-type oxidase. Our data showed that CcoQ is a single-spanning membrane protein with a N(out)-C(in) topology. In the absence of CcoQ, cbb(3)-type oxidase activity is significantly reduced, irrespective of the growth conditions. Blue native polyacrylamide gel electrophoresis analyses revealed that the lack of CcoQ specifically impaired the stable recruitment of CcoP into the cbb(3)-type oxidase complex. This suggested a specific CcoQ-CcoP interaction, which was confirmed by chemical cross-linking. Collectively, our data demonstrated that in R. capsulatus CcoQ was required for optimal cbb(3)-type oxidase activity because it stabilized the interaction of CcoP with the CcoNO core complex, leading subsequently to the formation of the active 230-kDa cbb(3)-type oxidase complex.
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75
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Helling S, Vogt S, Rhiel A, Ramzan R, Wen L, Marcus K, Kadenbach B. Phosphorylation and kinetics of mammalian cytochrome c oxidase. Mol Cell Proteomics 2008; 7:1714-24. [PMID: 18541608 DOI: 10.1074/mcp.m800137-mcp200] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The influence of protein phosphorylation on the kinetics of cytochrome c oxidase was investigated by applying Western blotting, mass spectrometry, and kinetic measurements with an oxygen electrode. The isolated enzyme from bovine heart exhibited serine, threonine, and/or tyrosine phosphorylation in various subunits, except subunit I, by using phosphoamino acid-specific antibodies. The kinetics revealed slight inhibition of oxygen uptake in the presence of ATP, as compared with the presence of ADP. Mass spectrometry identified the phosphorylation of Ser-34 at subunit IV and Ser-4 and Thr-35 at subunit Va. Incubation of the isolated enzyme with protein kinase A, cAMP, and ATP resulted in serine and threonine phosphorylation of subunit I, which was correlated with sigmoidal inhibition kinetics in the presence of ATP. This allosteric ATP-inhibition of cytochrome c oxidase was also found in rat heart mitochondria, which had been rapidly prepared in the presence of protein phosphatase inhibitors. The isolated rat heart enzyme, prepared from the mitochondria by blue native gel electrophoresis, showed serine, threonine, and tyrosine phosphorylation of subunit I. It is concluded that the allosteric ATP-inhibition of cytochrome c oxidase, previously suggested to keep the mitochondrial membrane potential and thus the reactive oxygen species production in cells at low levels, occurs in living cells and is based on phosphorylation of cytochrome c oxidase subunit I.
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Affiliation(s)
- Stefan Helling
- Medizinisches Proteom-Center, Funktionelle Proteomik, Ruhr-Universität Bochum, Germany
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76
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Bundschuh FA, Hoffmeier K, Ludwig B. Two variants of the assembly factor Surf1 target specific terminal oxidases in Paracoccus denitrificans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1336-43. [PMID: 18582433 DOI: 10.1016/j.bbabio.2008.05.448] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 05/26/2008] [Accepted: 05/27/2008] [Indexed: 02/06/2023]
Abstract
Biogenesis of cytochrome c oxidase (COX) relies on a large number of assembly proteins, one of them being Surf1. In humans, the loss of Surf1 function is associated with Leigh syndrome, a fatal neurodegenerative disorder. In the soil bacterium Paracoccus denitrificans, homologous genes specifying Surf1 have been identified and located in two operons of terminal oxidases: surf1q is the last gene of the qox operon (coding for a ba(3)-type ubiquinol oxidase), and surf1c is found at the end of the cta operon (encoding subunits of the aa(3)-type cytochrome c oxidase). We introduced chromosomal single and double deletions for both surf1 genes, leading to significantly reduced oxidase activities in membrane. Our experiments on P. denitrificans surf1 single deletion strains show that both Surf1c and Surf1q are functional and act independently for the aa(3)-type cytochrome c oxidase and the ba(3)-type quinol oxidase, respectively. This is the first direct experimental evidence for the involvement of a Surf1 protein in the assembly of a quinol oxidase. Analyzing the heme content of purified cytochrome c oxidase, we conclude that Surf1, though not indispensable for oxidase assembly, is involved in an early step of cofactor insertion into subunit I.
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Affiliation(s)
- Freya A Bundschuh
- Institut für Biochemie, Abteilung Molekulare Genetik, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.
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77
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Protein tethered lipid bilayer: An alternative mimic of the biological membrane (Mini Review). Biointerphases 2008; 3:FA101. [DOI: 10.1116/1.2936939] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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78
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Chapman EG, Piontkivska H, Walker JM, Stewart DT, Curole JP, Hoeh WR. Extreme primary and secondary protein structure variability in the chimeric male-transmitted cytochrome c oxidase subunit II protein in freshwater mussels: evidence for an elevated amino acid substitution rate in the face of domain-specific purifying selection. BMC Evol Biol 2008; 8:165. [PMID: 18513440 PMCID: PMC2430956 DOI: 10.1186/1471-2148-8-165] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 05/31/2008] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Freshwater unionoidean bivalves, and species representing two marine bivalve orders (Mytiloida and Veneroida), exhibit a mode of mtDNA inheritance involving distinct maternal (F) and paternal (M) transmission routes concomitant with highly divergent gender-associated mtDNA genomes. Additionally, male unionoidean bivalves have a approximately 550 bp 3' coding extension to the cox2 gene (Mcox2e), that is apparently absent from all other metazoan taxa. RESULTS Our molecular sequence analyses of MCOX2e indicate that both the primary and secondary structures of the MCOX2e region are evolving much faster than other regions of the F and M COX2-COX1 gene junction. The near N-terminus approximately 2/3 of the MCOX2e region contains an interspecifically variable number of predicted transmembrane helices (TMH) and interhelical loops (IHL) whereas the C-terminus approximately 1/3 is relatively conserved and hydrophilic while containing conserved functional motifs. MCOX2e displays an overall pattern of purifying selection that leads to the preservation of TMH/IHL and C-terminus tail sub-regions. However, 14 amino acid positions in the MCOX2e TMH/IHL sub-region might be targeted by diversifying selection, each representing a site where there exists interspecific variation for the constituent amino acids residing in a TMH or IHL. CONCLUSION Our results indicate that Mcox2e is unique to unionoidean bivalves, likely the result of a single insertion event that took place over 65 MYA and that MCOX2e is functional. The predicted TMH number, length and position variability likely stems from substitution-based processes rather than the typically implicated insertion/deletion events. MCOX2e has relatively high rates of primary and secondary structure evolution, with some amino acid residues potentially subjected to site-specific positive selection, yet an overall pattern of purifying selection leading to the preservation of the TMH/IHL and hydrophilic C-terminus tail subregions. The more conserved C-terminus tail (relative to the TMH/IHL sub-region of MCOX2e) is likely biologically active because it contains functional motifs. The rapid evolution of primary and secondary structure in MCOX2e, combined with the action of both positive and purifying selection, provide supporting evidence for the hypothesis that MCOX2e has a novel reproductive function within unionoidean bivalves. All tolled, our data indicate that unionoidean bivalve MCOX2 is the first reported chimeric animal mtDNA-encoded protein.
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Affiliation(s)
- Eric G Chapman
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Helen Piontkivska
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Jennifer M Walker
- Department of Biological Sciences, The University of Southern Mississippi, Long Beach, MS 39560, USA
| | | | - Jason P Curole
- University of Southern California, Los Angeles, CA 90089, USA
| | - Walter R Hoeh
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
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79
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The role of the conserved tryptophan272 of the Paracoccus denitrificans cytochrome c oxidase in proton pumping. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:925-8. [PMID: 18515062 DOI: 10.1016/j.bbabio.2008.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2008] [Revised: 04/06/2008] [Accepted: 05/10/2008] [Indexed: 11/20/2022]
Abstract
The catalytic mechanism of heme-copper oxidases - electron transfer coupled to proton pumping - is not yet fully understood. Single turnover experiments in which fully reduced cytochrome aa(3) from Paracoccus denitrificans reacts with O(2) using the microsecond freeze-hyperquenching sampling technique enabled trapping of transient catalytic intermediates and analysis by low temperature UV-Visible, X-band and Q-band EPR spectroscopy. Our recent findings (Wiertz et al. (2007) J. Biol. Chem. 282, 31580-31591), which show that the strictly conserved W272 is a redox active residue are reviewed here. The W272 forms a tryptophan neutral radical in the transition F-->F(W)-->O(H) in which the novel intermediate F(W) harbors the tryptophan radical. The potential role of W272 in proton pumping is highlighted.
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80
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In situ monitoring of the catalytic activity of cytochrome C oxidase in a biomimetic architecture. Biophys J 2008; 95:1500-10. [PMID: 18441024 DOI: 10.1529/biophysj.107.122747] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytochrome c oxidase (CcO) from Paracoccus denitrificans was immobilized in a strict orientation via a his-tag attached to subunit I on a gold film and reconstituted in situ into a protein-tethered bilayer lipid membrane. In this orientation, the cytochrome c (cyt c) binding site is directed away from the electrode pointing to the outer side of the protein-tethered bilayer lipid membrane architecture. The CcO can thus be activated by cyt c under aerobic conditions. Catalytic activity was monitored by impedance spectroscopy, as well as cyclic voltammetry. Cathodic and anodic currents of the CcO with cyt c added to the bulk solution were shown to increase under aerobic compared to anaerobic conditions. Catalytic activity was considered in terms of repeated electrochemical oxidation/reduction of the CcO/cyt c complex in the presence of oxygen. The communication of cyt c bound to the CcO with the electrode is discussed in terms of a hopping mechanism through the redox sites of the enzyme. Simulations supporting this hypothesis are included.
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81
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Elucidation of Electron- Transfer Pathways in Copper and Iron Proteins by Pulse Radiolysis Experiments. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/9780470144428.ch1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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82
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Lepp H, Svahn E, Faxén K, Brzezinski P. Charge Transfer in the K Proton Pathway Linked to Electron Transfer to the Catalytic Site in Cytochrome c Oxidase. Biochemistry 2008; 47:4929-35. [DOI: 10.1021/bi7024707] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Håkan Lepp
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Emelie Svahn
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Kristina Faxén
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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83
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Aging-induced alterations in gene transcripts and functional activity of mitochondrial oxidative phosphorylation complexes in the heart. Mech Ageing Dev 2008; 129:304-12. [PMID: 18400259 DOI: 10.1016/j.mad.2008.02.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2007] [Revised: 02/09/2008] [Accepted: 02/15/2008] [Indexed: 01/15/2023]
Abstract
Aging is associated with progressive decline in energetic reserves compromising cardiac performance and tolerance to injury. Although deviations in mitochondrial functions have been documented in senescent heart, the molecular bases for the decline in energy metabolism are only partially understood. Here, high-throughput transcription profiles of genes coding for mitochondrial proteins in ventricles from adult (6-months) and aged (24-months) rats were compared using microarrays. Out of 614 genes encoding for mitochondrial proteins, 94 were differentially expressed with 95% downregulated in the aged. The majority of changes affected genes coding for proteins involved in oxidative phosphorylation (39), substrate metabolism (14) and tricarboxylic acid cycle (6). Compared to adult, gene expression changes in aged hearts translated into a reduced mitochondrial functional capacity, with decreased NADH-dehydrogenase and F(0)F(1) ATPase complex activities and capacity for oxygen-utilization and ATP synthesis. Expression of genes coding for transcription co-activator factors involved in the regulation of mitochondrial metabolism and biogenesis were downregulated in aged ventricles without reduction in mitochondrial density. Thus, aging induces a selective decline in activities of oxidative phosphorylation complexes I and V within a broader transcriptional downregulation of mitochondrial genes, providing a substrate for reduced energetic efficiency associated with senescence.
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84
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da Fonseca RR, Johnson WE, O'Brien SJ, Ramos MJ, Antunes A. The adaptive evolution of the mammalian mitochondrial genome. BMC Genomics 2008; 9:119. [PMID: 18318906 PMCID: PMC2375446 DOI: 10.1186/1471-2164-9-119] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2007] [Accepted: 03/04/2008] [Indexed: 11/18/2022] Open
Abstract
Background The mitochondria produce up to 95% of a eukaryotic cell's energy through oxidative phosphorylation. The proteins involved in this vital process are under high functional constraints. However, metabolic requirements vary across species, potentially modifying selective pressures. We evaluate the adaptive evolution of 12 protein-coding mitochondrial genes in 41 placental mammalian species by assessing amino acid sequence variation and exploring the functional implications of observed variation in secondary and tertiary protein structures. Results Wide variation in the properties of amino acids were observed at functionally important regions of cytochrome b in species with more-specialized metabolic requirements (such as adaptation to low energy diet or large body size, such as in elephant, dugong, sloth, and pangolin, and adaptation to unusual oxygen requirements, for example diving in cetaceans, flying in bats, and living at high altitudes in alpacas). Signatures of adaptive variation in the NADH dehydrogenase complex were restricted to the loop regions of the transmembrane units which likely function as protons pumps. Evidence of adaptive variation in the cytochrome c oxidase complex was observed mostly at the interface between the mitochondrial and nuclear-encoded subunits, perhaps evidence of co-evolution. The ATP8 subunit, which has an important role in the assembly of F0, exhibited the highest signal of adaptive variation. ATP6, which has an essential role in rotor performance, showed a high adaptive variation in predicted loop areas. Conclusion Our study provides insight into the adaptive evolution of the mtDNA genome in mammals and its implications for the molecular mechanism of oxidative phosphorylation. We present a framework for future experimental characterization of the impact of specific mutations in the function, physiology, and interactions of the mtDNA encoded proteins involved in oxidative phosphorylation.
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Affiliation(s)
- Rute R da Fonseca
- REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
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85
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Electronic wiring of a multi-redox site membrane protein in a biomimetic surface architecture. Biophys J 2008; 94:3698-705. [PMID: 18222995 DOI: 10.1529/biophysj.107.117846] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bioelectronic coupling of multi-redox-site membrane proteins was accomplished with cytochrome c oxidase (CcO) as an example. A biomimetic membrane system was used for the oriented immobilization of the CcO oxidase on a metal electrode. When the protein is immobilized with the CcO binding side directed toward the electrode and reconstituted in situ into a lipid bilayer, it is addressable by direct electron transfer to the redox centers. Electron transfer to the enzyme via the spacer, referred to as electronic wiring, shows an exceptionally high rate constant. This allows a kinetic analysis of all four consecutive electron transfer steps within the enzyme to be carried out. Electron transfer followed by rapid scan cyclic voltammetry in combination with surface-enhanced resonance Raman spectroscopy provides mechanistic and structural information about the heme centers. Probing the enzyme under turnover conditions showed mechanistic insights into proton translocation coupled to electron transfer. This bioelectronic approach opens a new field of activity to investigate complex processes in a wide variety of membrane proteins.
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86
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Kaplan P, Tatarkova Z, Racay P, Lehotsky J, Pavlikova M, Dobrota D. Oxidative modifications of cardiac mitochondria and inhibition of cytochrome c oxidase activity by 4-hydroxynonenal. Redox Rep 2007; 12:211-8. [PMID: 17925093 DOI: 10.1179/135100007x200308] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
4-hydroxynonenal (HNE) is a highly toxic product of lipid peroxidation (LPO). Its role in the inhibition of cytochrome c oxidase activity and oxidative modifications of mitochondrial lipids and proteins were investigated. The exposure of mitochondria isolated from rat heart to HNE resulted in a time- and concentration-dependent inhibition of cytochrome c oxidase activity with an IC50 value of 8.3 +/- 1.0 microM. Immunoprecipitation-Western blot analysis showed the formation of HNE adducts with cytochrome c oxidase subunit I. The loss of cytochrome c oxidase activity was also accompanied by reduced thiol group content and increased HNE-lysine fluorescence. Furthermore, there was a marked increase in conjugated diene formation indicating LPO induction by HNE. Fluorescence measurements revealed the formation of bityrosines and increased surface hydrophobicity of HNE-treated mitochondrial membranes. Superoxide dismutase + catalase and the HO* radical scavenger mannitol partially prevented inhibition of cytochrome c oxidase activity and formation of bityrosines. These findings suggest that HNE induces formation of reactive oxygen species and its damaging effect on mitochondria involves both formation of HNE-protein adducts and oxidation of membrane lipids and proteins by free radicals.
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Affiliation(s)
- Peter Kaplan
- Department of Biochemistry, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic.
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87
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Banci L, Bertini I, Ciofi-Baffoni S, Gerothanassis IP, Leontari I, Martinelli M, Wang S. A structural characterization of human SCO2. Structure 2007; 15:1132-40. [PMID: 17850752 DOI: 10.1016/j.str.2007.07.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 07/12/2007] [Accepted: 07/16/2007] [Indexed: 11/19/2022]
Abstract
Human Sco2 is a mitochondrial membrane-bound protein involved in copper supply for the assembly of cytochrome c oxidase in eukaryotes. Its precise action is not yet understood. We report here a structural and dynamic characterization by NMR of the apo and copper(I) forms of the soluble fragment. The structural and metal binding features of human Cu(I)Sco2 are similar to the more often studied Sco1 homolog, although the dynamic properties and the conformational disorder are quite different when the apo forms and the copper(I)-loaded forms of the two proteins are compared separately. Such differences are accounted for in terms of the different physicochemical properties in strategic protein locations. The misfunction of the known pathogenic mutations is discussed on the basis of the obtained structure.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
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88
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Bertini I, Cavallaro G. Metals in the “omics” world: copper homeostasis and cytochrome c oxidase assembly in a new light. J Biol Inorg Chem 2007; 13:3-14. [DOI: 10.1007/s00775-007-0316-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 10/25/2007] [Indexed: 01/20/2023]
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89
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Chakrabarti R, Walker JM, Chapman EG, Shepardson SP, Trdan RJ, Curole JP, Watters GT, Stewart DT, Vijayaraghavan S, Hoeh WR. Reproductive function for a C-terminus extended, male-transmitted cytochrome c oxidase subunit II protein expressed in both spermatozoa and eggs. FEBS Lett 2007; 581:5213-9. [PMID: 17950289 DOI: 10.1016/j.febslet.2007.10.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/03/2007] [Accepted: 10/04/2007] [Indexed: 11/25/2022]
Abstract
Our previous study documented expression of a male-transmitted cytochrome c oxidase subunit II protein (MCOX2), with a C-terminus extension (MCOX2e), in unionoidean bivalve testes and sperm mitochondria. Here, we present evidence demonstrating that MCOX2 is seasonally expressed in testis, with a peak shortly before fertilization that is independent of sperm density. MCOX2 is localized to the inner and outer sperm mitochondrial membranes and the MCOX2 antibody's epitope is conserved across >65 million years of evolution. We also demonstrate the presence of male-transmitted mtDNA and season-specific MCOX2 spatial variation in ovaries. We hypothesize that MCOX2 plays a role in reproduction through gamete maturation, fertilization and/or embryogenesis.
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Affiliation(s)
- R Chakrabarti
- Department of Biochemistry, State University of New York, Buffalo, NY 14214, USA.
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90
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Wiertz FGM, Richter OMH, Ludwig B, de Vries S. Kinetic Resolution of a Tryptophan-radical Intermediate in the Reaction Cycle of Paracoccus denitrificans Cytochrome c Oxidase. J Biol Chem 2007; 282:31580-91. [PMID: 17761680 DOI: 10.1074/jbc.m705520200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The catalytic mechanism, electron transfer coupled to proton pumping, of heme-copper oxidases is not yet fully understood. Microsecond freeze-hyperquenching single turnover experiments were carried out with fully reduced cytochrome aa(3) reacting with O(2) between 83 micros and 6 ms. Trapped intermediates were analyzed by low temperature UV-visible, X-band, and Q-band EPR spectroscopy, enabling determination of the oxidation-reduction kinetics of Cu(A), heme a, heme a(3), and of a recently detected tryptophan radical (Wiertz, F. G. M., Richter, O. M. H., Cherepanov, A. V., MacMillan, F., Ludwig, B., and de Vries, S. (2004) FEBS Lett. 575, 127-130). Cu(B) and heme a(3) were EPR silent during all stages of the reaction. Cu(A) and heme a are in electronic equilibrium acting as a redox pair. The reduction potential of Cu(A) is 4.5 mV lower than that of heme a. Both redox groups are oxidized in two phases with apparent half-lives of 57 micros and 1.2 ms together donating a single electron to the binuclear center in each phase. The formation of the heme a(3) oxoferryl species P(R) (maxima at 430 nm and 606 nm) was completed in approximately 130 micros, similar to the first oxidation phase of Cu(A) and heme a. The intermediate F (absorbance maximum at 571 nm) is formed from P(R) and decays to a hitherto undetected intermediate named F(W)(*). F(W)(*) harbors a tryptophan radical, identified by Q-band EPR spectroscopy as the tryptophan neutral radical of the strictly conserved Trp-272 (Trp-272(*)). The Trp-272(*) populates to 4-5% due to its relatively low rate of formation (t((1/2)) = 1.2 ms) and rapid rate of breakdown (t((1/2)) = 60 micros), which represents electron transfer from Cu(A)/heme a to Trp-272(*). The formation of the Trp-272(*) constitutes the major rate-determining step of the catalytic cycle. Our findings show that Trp-272 is a redox-active residue and is in this respect on an equal par to the metallocenters of the cytochrome c oxidase. Trp-272 is the direct reductant either to the heme a(3) oxoferryl species or to Cu (2+)(B). The potential role of Trp-272 in proton pumping is discussed.
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Affiliation(s)
- Frank G M Wiertz
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands
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91
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Vygodina TV, Konstantinov AA. Peroxidase activity of mitochondrial cytochrome c oxidase. BIOCHEMISTRY (MOSCOW) 2007; 72:1056-64. [DOI: 10.1134/s0006297907100045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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92
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Katyare SS, Patel SP, Modi HR. Diabetic modulation of the temperature kinetics properties of cytochrome oxidase activity in rat brain mitochondria. Neurochem Res 2007; 33:422-9. [PMID: 17721819 DOI: 10.1007/s11064-007-9447-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Accepted: 07/17/2007] [Indexed: 11/26/2022]
Abstract
The effects of alloxan-diabetes and subsequent treatment with insulin on temperature kinetics properties of cytochrome oxidase activity from rat brain mitochondria were examined. The enzyme activity decreased only at the late stage of diabetes which was not normalized by insulin treatment; however at early stage of diabetes hyper-stimulation occurred. In the control animals the Arrhenius plot was chair shaped with three energies of (E1, E2 and E3) and two phase transition temperatures (Tt1 and Tt2). At early diabetic stage the Arrhenius plot became biphasic and E1)and E2 decreased; insulin treatment reversed chair-shaped pattern with increase in E2. These changes correlated with transient changes in the phospholipids profiles especially decreased acidic phospholipids. The temperature kinetics parameters were minimally affected at the late stage of diabetes or by insulin treatment. Thus at the late stage the brain tissue seems to have readjusted to its insulin homeostasis.
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Affiliation(s)
- Surendra S Katyare
- Department of Biochemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, 390 002 Gujarat, India
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93
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Morgner N, Kleinschroth T, Barth HD, Ludwig B, Brutschy B. A novel approach to analyze membrane proteins by laser mass spectrometry: from protein subunits to the integral complex. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:1429-38. [PMID: 17544294 DOI: 10.1016/j.jasms.2007.04.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 04/20/2007] [Accepted: 04/24/2007] [Indexed: 05/15/2023]
Abstract
A novel laser-based mass spectrometry method termed LILBID (laser-induced liquid bead ion desorption) is applied to analyze large integral membrane protein complexes and their subunits. In this method the ions are IR-laser desorbed from aqueous microdroplets containing the hydrophobic protein complexes solubilized by detergent. The method is highly sensitive, very efficient in sample handling, relatively tolerant to various buffers, and detects the ions in narrow, mainly low-charge state distributions. The crucial experimental parameter determining whether the integral complex or its subunits are observed is the laser intensity: At very low intensity level corresponding to an ultrasoft desorption, the intact complexes, together with few detergent molecules, are transferred into vacuum. Under these conditions the oligomerization state of the complex (i.e., its quaternary structure) may be analyzed. At higher laser intensity, complexes are thermolyzed into subunits, with any residual detergent being stripped off to yield the true mass of the polypeptides. The model complexes studied are derived from the respiratory chain of the soil bacterium Paracoccus denitrificans and include complexes III (cytochrome bc(1) complex) and IV (cytochrome c oxidase). These are well characterized multi-subunit membrane proteins, with the individual hydrophobic subunits being composed of up to 12 transmembrane helices.
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Affiliation(s)
- Nina Morgner
- Institute for Physical and Theoretical Chemistry, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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94
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Liu X, Zhou B, Mi S, Xue L, Shih J, Lee J, Chau J, Un F, Yen Y. An increase of cytochrome C oxidase mediated disruption of gemcitabine incorporation into DNA in a resistant KB clone. Biochem Pharmacol 2007; 73:1927-38. [PMID: 17428446 PMCID: PMC1950577 DOI: 10.1016/j.bcp.2007.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 03/14/2007] [Accepted: 03/15/2007] [Indexed: 12/15/2022]
Abstract
Mechanistic aberrations leading to Gemcitabine (2',2'-dFdCyd,2,2-difluorodeoxycytidine, Gem) resistance may include alteration in its transport, metabolism and incorporation into DNA. To explore the mechanism of Gem resistance, the restriction fragment differential display PCR (RFDD-PCR) was employed to compare the mRNA expression patterns of KBGem (Gem resistant), KBHURs (hydroxyurea resistant) and KBwt (parental KB cell). Nine gene fragments were overexpressed specifically in the KBGem clone. Sequencing and BLAST results showed that three fragments represent cytochrome C oxidase (CCOX, respiration complex IV) subunit III (CCOX3). The cDNA microarray confirmed that the mRNAs of CCOX and ATP synthase subunits were upregulated in KBGem as compared to KBwt and KBHURs. The increase in CCOX1 protein and activity led to the increase of free ATP concentration, which is consistent with the gene expression profile of KBGem. Furthermore, the sensitivity to Gem could be reversed by sodium azide, a CCOX inhibitor. Following the treatment of sodium azide, the cellular accumulation of [3H]-Gem increased in a dose (of azide)-dependent manner, which is associated with increase of [3H]-Gem incorporation into DNA in KBGem. In summary, an increase of CCOX activity and free ATP level may reduce the transport, metabolism and DNA incorporation of Gem, resulting in Gem resistance.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Yun Yen
- Correspondence: Yun Yen, M.D., Ph.D., F.A.C.P., Department of Clinical & Molecular Pharmacology, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010-3000, Phone: (626) 359-8111 ext. 62867, Fax: (626) 301-8233, E-mail:
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95
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Pilet E, Nitschke W, Liebl U, Vos MH. Accommodation of NO in the active site of mammalian and bacterial cytochrome c oxidase aa3. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:387-92. [PMID: 17434442 DOI: 10.1016/j.bbabio.2007.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 02/23/2007] [Accepted: 03/01/2007] [Indexed: 10/23/2022]
Abstract
Following different reports on the stoichiometry and configuration of NO binding to mammalian and bacterial reduced cytochrome c oxidase aa(3) (CcO), we investigated NO binding and dynamics in the active site of beef heart CcO as a function of NO concentration, using ultrafast transient absorption and EPR spectroscopy. We find that in the physiological range only one NO molecule binds to heme a(3), and time-resolved experiments indicate that even transient binding to Cu(B) does not occur. Only at very high (approximately 2 mM) concentrations a second NO is accommodated in the active site, although in a different configuration than previously observed for CcO from Paracoccus denitrificans [E. Pilet, W. Nitschke, F. Rappaport, T. Soulimane, J.-C. Lambry, U. Liebl and M.H. Vos. Biochemistry 43 (2004) 14118-14127], where we proposed that a second NO does bind to Cu(B). In addition, in the bacterial enzyme two NO molecules can bind already at NO concentrations of approximately 1 microM. The unexpected differences highlighted in this study may relate to differences in the physiological relevance of the CcO-NO interactions in both species.
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Affiliation(s)
- Eric Pilet
- Laboratoire d'Optique et Biosciences, CNRS, Ecole Polytechnique, F-91128 Palaiseau Cedex, France
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96
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Tisdall MM, Tachtsidis I, Leung TS, Elwell CE, Smith M. Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemia. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:024002. [PMID: 17477717 DOI: 10.1117/1.2718541] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The near-IR cytochrome c oxidase (CCO) signal has potential as a clinical marker of changes in mitochondrial oxygen utilization. We examine the CCO signal response to reduced oxygen delivery in the healthy human brain. We induced a reduction in arterial oxygen saturation from baseline levels to 80% in eight healthy adult humans, while minimizing changes in end tidal carbon dioxide tension. We measured changes in the cerebral concentrations of oxidized CCO (Delta[oxCCO]), oxyhemoglobin (Delta[HbO(2)]), and deoxyhemoglobin (Delta[HHb]) using broadband near-IR spectroscopy (NIRS), and estimated changes in cerebral oxygen delivery (ecDO(2)) using pulse oximetry and transcranial Doppler ultrasonography. Results are presented as median (interquartile range). At the nadir of hypoxemia ecDO(2) decreased by 9.2 (5.4 to 12.1)% (p<0.0001), Delta[oxCCO] decreased by 0.24 (0.06 to 0.28) micromoles/l (p<0.01), total hemoglobin concentration increased by 2.83 (2.27 to 4.46) micromoles/l (p<0.0001), and change in hemoglobin difference concentration (Delta[Hbdiff]=Delta[HbO(2)]-Delta[HHb]) decreased by 12.72 (11.32 to 16.34) micromoles/l (p<0.0001). Change in ecDO(2) correlated with Delta[oxCCO] (r=0.78, p<0.001), but not with either change in total hemoglobin concentration or Delta[Hbdiff]. This is the first description of cerebral Delta[oxCCO] during hypoxemia in healthy adults. Studies are ongoing to investigate the clinical relevance of this signal in patients with traumatic brain injury.
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Affiliation(s)
- Martin M Tisdall
- The National Hospital for Neurology and Neurosurgery, Department of Neuroanaesthesia and Neurocritical Care, Queen Square, London WC1N 3BG, United Kingdom.
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97
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Boekema EJ, Braun HP. Supramolecular Structure of the Mitochondrial Oxidative Phosphorylation System. J Biol Chem 2007; 282:1-4. [PMID: 17102127 DOI: 10.1074/jbc.r600031200] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein complexes of the mitochondrial oxidative phosphorylation system were recently reported to form supramolecular assemblies termed respiratory supercomplexes or respirasomes. These supercomplexes are considered to be of great functional importance. Here we review new insights into supercomplex structure and physiology.
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Affiliation(s)
- Egbert J Boekema
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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98
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Tachtsidis I, Tisdall M, Leung TS, Cooper CE, Delpy DT, Smith M, Elwell CE. Investigation ofin vivomeasurement of cerebral cytochrome-c-oxidase redox changes using near-infrared spectroscopy in patients with orthostatic hypotension. Physiol Meas 2006; 28:199-211. [PMID: 17237591 DOI: 10.1088/0967-3334/28/2/008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have previously used a continuous four-wavelength near-infrared spectrometer to measure changes in the cerebral concentrations of oxy-haemoglobin (Delta[HbO(2)] and deoxy-haemoglobin (Delta[HHb]) during head-up tilt in patients with primary autonomic failure. The measured changes in light attenuation also allow calculation of changes in the concentration of oxidized cytochrome-c-oxidase (Delta[(ox)CCO]), and this paper analyses the Delta[(ox)CCO] during the severe episodes of orthostatic hypotension produced by this experimental protocol. We studied 12 patients during a passive change in position from supine to a 60 degrees head-up tilt. The challenge caused a reduction in mean blood pressure of 59.93 (+/-26.12) mmHg (Mean (+/-SD), p < 0.0001), which was associated with a reduction in the total concentration of haemoglobin (Delta[HbT] = Delta[HbO(2)] + Delta[HHb]) of 5.02 (+/-3.81) microM (p < 0.0001) and a reduction in the haemoglobin difference concentration (Delta[Hb(diff)] = Delta[HbO(2)] - Delta[HHb]) of 14.4 (+/-6.73) microM (p < 0.0001). We observed a wide range of responses in Delta[(ox)CCO]. Six patients demonstrated a drop in Delta[(ox)CCO] (0.17 +/- 0.15 microM); four patients demonstrated no change (0.01 +/- 0.12 microM) and two patients showed an increase in Delta[(ox)CCO] (0.21 +/- 0.01 microM). Investigation of the association between the changes in concentrations of haemoglobin species and the Delta[(ox)CCO] for each patient show a range of relationships. This suggests that a simple mechanism for crosstalk, which might produce artefactual changes in [(ox)CCO], is not present between the haemoglobin and the (ox)CCO NIRS signals. Further investigation is required to determine the clinical significance of the changes in [(ox)CCO].
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Affiliation(s)
- I Tachtsidis
- Department of Medical Physics and Bioengineering, Malet Place Engineering Building, University College London, Gower Street, London, UK.
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99
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Farver O, Chen Y, Fee JA, Pecht I. Electron transfer among the CuA-, heme b- and a3-centers of Thermus thermophilus cytochrome ba3. FEBS Lett 2006; 580:3417-21. [PMID: 16712843 DOI: 10.1016/j.febslet.2006.05.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 04/27/2006] [Accepted: 05/03/2006] [Indexed: 10/24/2022]
Abstract
The 1-methyl-nicotinamide radical (MNA(*)), produced by pulse radiolysis has previously been shown to reduce the Cu(A)-site of cytochromes aa(3), a process followed by intramolecular electron transfer (ET) to the heme a but not to the heme a(3) [Farver, O., Grell, E., Ludwig, B., Michel, H. and Pecht, I. (2006) Rates and equilibrium of CuA to heme a electron transfer in Paracoccus denitrificans cytochrome c oxidase. Biophys. J. 90, 2131-2137]. Investigating this process in the cytochrome ba(3) of Thermus thermophilus (Tt), we now show that MNA(*) also reduces Cu(A) with a subsequent ET to the heme b and then to heme a(3), with first-order rate constants 11200 s(-1), and 770 s(-1), respectively. The results provide clear evidence for ET among the three spectroscopically distinguishable centers and indicate that the binuclear a(3)-Cu(B) center can be reduced in molecules containing a single reduction equivalent.
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Affiliation(s)
- Ole Farver
- Institute of Analytical Chemistry, The Danish University of Pharmaceutical Sciences, Copenhagen, Denmark
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100
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Converso DP, Taillé C, Carreras MC, Jaitovich A, Poderoso JJ, Boczkowski J. HO‐1 is located in liver mitochondria and modulates mitochondrial heme content and metabolism. FASEB J 2006; 20:1236-8. [PMID: 16672635 DOI: 10.1096/fj.05-4204fje] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study investigated whether inducible heme oxygenase-1[corrected] (HO-1) [corrected] is targeted to mitochondria and its putative effects on oxidative metabolism in rat liver. Western blot and immune-electron microscopy in whole purified and fractionated organelles showed basal expression of HO-1 protein in both microsomes and mitochondria (inner membrane), accompanied by a parallel HO activity. Inducers of HO-1 increased HO-1 targeting to the inner mitochondrial membrane, which also contained biliverdin reductase, supporting that both enzymes are in the same compartmentalization. Induction of mitochondrial HO-1 was associated with a decrease of mitochondrial heme content and selective reduction of protein expression of cytochrome oxidase (COX) subunit I, which is coded by the mitochondrial genome and synthesized in the mitochondria depending on heme availability; these changes resulted in decreased COX spectrum and activity. Mitochondrial HO-1 induction was also associated with down-regulation of mitochondrial-targeted NO synthase expression and activity, resulting in a reduction of NO-dependent mitochondrial oxidant yield; inhibition of HO-1 activity reverted these effects. In conclusion, we demonstrated for the first time localization of HO-1 protein in mitochondria. It is surmised that mitochondrial HO-1 has important biological roles in regulating mitochondrial heme protein turnover and in protecting against conditions such as hypoxia, neurodegenerative diseases, or sepsis, in which substantially increased mitochondrial NO and oxidant production have been implicated.
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Affiliation(s)
- Daniela P Converso
- Laboratory of Oxygen Metabolism, University Hospital, University of Buenos Aires, Argentina
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