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Neuroprotective Potential of Mild Uncoupling in Mitochondria. Pros and Cons. Brain Sci 2021; 11:brainsci11081050. [PMID: 34439669 PMCID: PMC8392724 DOI: 10.3390/brainsci11081050] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
There has been an explosion of interest in the use of uncouplers of oxidative phosphorylation in mitochondria in the treatment of several pathologies, including neurological ones. In this review, we analyzed all the mechanisms associated with mitochondrial uncoupling and the metabolic and signaling cascades triggered by uncouplers. We provide a full set of positive and negative effects that should be taken into account when using uncouplers in experiments and clinical practice.
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Prasad A, Mastud P, Patankar S. Dually localised proteins found in both the apicoplast and mitochondrion utilize the Golgi-dependent pathway for apicoplast targeting in Toxoplasma gondii. Biol Cell 2020; 113:58-78. [PMID: 33112425 DOI: 10.1111/boc.202000050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 10/07/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND INFORMATION Like other apicomplexan parasites, Toxoplasma gondii harbours a four-membraned endosymbiotic organelle - the apicoplast. Apicoplast proteins are nuclear encoded and trafficked to the organelle through the endoplasmic reticulum (ER). From the ER to the apicoplast, two distinct protein trafficking pathways can be used. One such pathway is the cell's secretory pathway involving the Golgi, whereas the other is a unique Golgi-independent pathway. Using different experimental approaches, many apicoplast proteins have been shown to utilize the Golgi-independent pathway, whereas a handful of reports show that a few proteins use the Golgi-dependent pathway. This has led to an emphasis towards the unique Golgi-independent pathway when apicoplast protein trafficking is discussed in the literature. Additionally, the molecular features that drive proteins to each pathway are not known. RESULTS In this report, we systematically test eight apicoplast proteins, using a C-terminal HDEL sequence to assess the role of the Golgi in their transport. We demonstrate that dually localised proteins of the apicoplast and mitochondrion (TgSOD2, TgTPx1/2 and TgACN/IRP) are trafficked through the Golgi, whereas proteins localised exclusively to the apicoplast are trafficked independent of the Golgi. Mutants of the dually localised proteins that localised exclusively to the apicoplast also showed trafficking through the Golgi. Phylogenetic analysis of TgSOD2, TgTPx1/2 and TgACN/IRP suggested that the evolutionary origins of TgSOD2 and TgTPx1/2 lie in the mitochondrion, whereas TgACN/IRP appears to have originated from the apicoplast. CONCLUSIONS AND SIGNIFICANCE Collectively, with these results, for the first time, we establish that the driver of the Golgi-dependent trafficking route to the apicoplast is the dual localisation of the protein to the apicoplast and the mitochondrion.
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Affiliation(s)
- Aparna Prasad
- Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Pragati Mastud
- Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Swati Patankar
- Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Rajapakse K, Drobne D, Kastelec D, Kogej K, Makovec D, Gallampois C, Amelina H, Danielsson G, Fanedl L, Marinsek-Logar R, Cristobal S. Proteomic analyses of early response of unicellular eukaryotic microorganism Tetrahymena thermophila exposed to TiO₂ particles. Nanotoxicology 2015; 10:542-56. [PMID: 26524663 DOI: 10.3109/17435390.2015.1091107] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Key biological functions involved in cell survival have been studied to understand the difference between the impact of exposure to TiO2 nanoparticles (TiO2-NPs) and their bulk counterparts (bulk-TiO2). By selecting a unicellular eukaryotic model organism and applying proteomic analysis an overview of the possible impact of exposure could be obtained. In this study, we investigated the early response of unicellular eukaryotic protozoan Tetrahymena thermophila exposed to TiO2-NPs or bulk-TiO2 particles at subtoxic concentrations for this organism. The proteomic analysis based on 2DE + nLC-ESI-MS/MS revealed 930 distinct protein spots, among which 77 were differentially expressed and 18 were unambiguously identified. We identified alterations in metabolic pathways, including lipid and fatty acid metabolism, purine metabolism and energetic metabolism, as well as salt stress and protein degradation. This proteomic study is consistent with our previous findings, where the early response of T. thermophila to subtoxic concentrations of TiO2 particles included alterations in lipid and fatty acid metabolism and ion regulation. The response to the lowest TiO2-NPs concentration differed significantly from the response to higher TiO2-NPs concentration and both bulk-TiO2 concentrations. Alterations on the physiological landscape were significant after exposure to both nano- and bulk-TiO2; however, no toxic effects were evidenced even at very high exposure concentrations. This study confirms the relevance of the alteration of the lipid profile and lipid metabolism in understanding the early impact of TiO2-NPs in eukaryotic cells, for example, phagocytosing cells like macrophages and ciliated cells in the respiratory epithelium.
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Affiliation(s)
| | | | | | - K Kogej
- d Faculty of Chemistry and Chemical Technology , University of Ljubljana , Ljubljana , Slovenia
| | - D Makovec
- e Jožef Stefan Institute , Ljubljana , Slovenia
| | - C Gallampois
- f Department of Clinical and Experimental Medicine , Cell Biology, Medical Faculty, Linköping University , Linköping , Sweden
| | - H Amelina
- g Department of Biochemistry and Biophysics , Stockholm University , Stockholm , Sweden
| | - G Danielsson
- g Department of Biochemistry and Biophysics , Stockholm University , Stockholm , Sweden
| | - L Fanedl
- h Biotechnical Faculty, Department of Animal Science , University of Ljubjana , Slovenia , and
| | - R Marinsek-Logar
- h Biotechnical Faculty, Department of Animal Science , University of Ljubjana , Slovenia , and
| | - S Cristobal
- f Department of Clinical and Experimental Medicine , Cell Biology, Medical Faculty, Linköping University , Linköping , Sweden .,i Department of Physiology , Faculty of Medicine and Dentistry, IKERBASQUE, Basque Foundation for Science, University of the Basque Country , Leioa , Spain
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Bychkova VE, Basova LV, Balobanov VA. How membrane surface affects protein structure. BIOCHEMISTRY (MOSCOW) 2015; 79:1483-514. [DOI: 10.1134/s0006297914130045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Zhang C, Marcia M, Langer JD, Peng G, Michel H. Role of the N-terminal signal peptide in the membrane insertion ofAquifex aeolicusF1F0ATP synthase c-subunit. FEBS J 2013; 280:3425-35. [DOI: 10.1111/febs.12336] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Chunli Zhang
- Max Planck Institute of Biophysics; Department of Molecular Membrane Biology; Frankfurt am Main Germany
| | - Marco Marcia
- Department of Molecular, Cellular and Developmental Biology; Yale University; New Haven CT USA
| | - Julian D. Langer
- Max Planck Institute of Biophysics; Department of Molecular Membrane Biology; Frankfurt am Main Germany
| | - Guohong Peng
- Max Planck Institute of Biophysics; Department of Molecular Membrane Biology; Frankfurt am Main Germany
- Institute of Oceanology; Chinese Academy of Sciences; Qingdao China
| | - Hartmut Michel
- Max Planck Institute of Biophysics; Department of Molecular Membrane Biology; Frankfurt am Main Germany
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Characterization of alcohol dehydrogenase 3 of the thermotolerant methylotrophic yeast Hansenula polymorpha. Appl Microbiol Biotechnol 2012; 96:697-709. [DOI: 10.1007/s00253-011-3866-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 12/20/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
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Poulsen JB, Andersen KR, Kjær KH, Durand F, Faou P, Vestergaard AL, Talbo GH, Hoogenraad N, Brodersen DE, Justesen J, Martensen PM. Human 2'-phosphodiesterase localizes to the mitochondrial matrix with a putative function in mitochondrial RNA turnover. Nucleic Acids Res 2011; 39:3754-70. [PMID: 21245038 PMCID: PMC3089451 DOI: 10.1093/nar/gkq1282] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The vertebrate 2-5A system is part of the innate immune system and central to cellular antiviral defense. Upon activation by viral double-stranded RNA, 5'-triphosphorylated, 2'-5'-linked oligoadenylate polyribonucleotides (2-5As) are synthesized by one of several 2'-5'-oligoadenylate synthetases. These unusual oligonucleotides activate RNase L, an unspecific endoribonuclease that mediates viral and cellular RNA breakdown. Subsequently, the 2-5As are removed by a 2'-phosphodiesterase (2'-PDE), an enzyme that apart from breaking 2'-5' bonds also degrades regular, 3'-5'-linked oligoadenylates. Interestingly, 2'-PDE shares both functionally and structurally characteristics with the CCR4-type exonuclease-endonuclease-phosphatase family of deadenylases. Here we show that 2'-PDE locates to the mitochondrial matrix of human cells, and comprise an active 3'-5' exoribonuclease exhibiting a preference for oligo-adenosine RNA like canonical cytoplasmic deadenylases. Furthermore, we document a marked negative association between 2'-PDE and mitochondrial mRNA levels following siRNA-directed knockdown and plasmid-mediated overexpression, respectively. The results indicate that 2'-PDE, apart from playing a role in the cellular immune system, may also function in mitochondrial RNA turnover.
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Della-Cioppa G, Bauer SC, Klein BK, Shah DM, Fraley RT, Kishore GM. Translocation of the precursor of 5-enolpyruvylshikimate-3-phosphate synthase into chloroplasts of higher plants in vitro. Proc Natl Acad Sci U S A 2010; 83:6873-7. [PMID: 16593759 PMCID: PMC386612 DOI: 10.1073/pnas.83.18.6873] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
5-enolPyruvylshikimate-3-phosphate synthase (EPSP synthase; 3-phosphoshikimate 1-carboxyvinyl-transferase; EC 2.5.1.19) is a chloroplast-localized enzyme of the shikimate pathway in plants. This enzyme is the target for the nonselective herbicide glyphosate (N-phosphonomethylglycine). We have previously isolated a full-length cDNA clone of EPSP synthase from Petunia hybrida. DNA sequence analysis suggested that the enzyme is synthesized as a cytosolic precursor (pre-EPSP synthase) with an amino-terminal transit peptide. Based on the known amino terminus of the mature enzyme, and the 5' open reading frame of the cDNA, the transit peptide of pre-EPSP synthase would be maximally 72 amino acids long. To confirm this prediction and to assay directly for translocation of pre-EPSP synthase into chloroplasts in vitro, we cloned the full-length cDNA into an SP6 transcription system to produce large amounts of mRNA for in vitro translation. The translation products, when analyzed by NaDodSO(4)/PAGE autoradiography, indicate a relative molecular mass for pre-EPSP synthase of approximately 55 kDa. Uptake studies with intact chloroplasts, in vitro, indicate that pre-EPSP synthase was rapidly taken up into chloroplasts and proteolytically cleaved to the mature approximately 48-kDa enzyme. The transit peptide was shown to be essential for import of the precursor enzyme into the chloroplast. To our knowledge, post-translational import into chloroplasts of a precursor enzyme involved in amino acid biosynthesis has not been reported previously. Furthermore, enzymatic analysis of translation products indicates that pre-EPSP synthase is catalytically active and has a similar sensitivity to the herbicide glyphosate as the mature enzyme. To our knowledge, pre-EPSP synthase represents the only example of a catalytically competent chloroplast-precursor enzyme.
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Affiliation(s)
- G Della-Cioppa
- Monsanto Company, Plant Molecular Biology Group, Division of Biological Sciences, 700 Chesterfield Village Parkway, St. Louis, MO 63198
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Lubben TH, Keegstra K. Efficient in vitro import of a cytosolic heat shock protein into pea chloroplasts. Proc Natl Acad Sci U S A 2010; 83:5502-6. [PMID: 16593735 PMCID: PMC386315 DOI: 10.1073/pnas.83.15.5502] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In order to further our understanding of the targeting of nuclear-encoded proteins into intracellular organelles, we have investigated the import of chimeric precursor proteins into pea chloroplasts. Two different chimeric precursor proteins were produced by in vitro expression of chimeric genes. One chimeric precursor contained the transit peptide of the small subunit of soybean ribulose 1,5-bisphosphate carboxylase and the mature peptide of the same protein from pea. The second contained the same transit peptide plus 13 amino acids of the pea mature peptide fused to a cytosolic heat shock protein. The extent of import and binding of the two chimeric proteins was examined by using quantitative assays and was compared to the import of pea small subunit precursor. Both precursor proteins imported well into pea chloroplasts, although the extent of import observed with the chimeric small-subunit-heat shock precursor was less than that observed with the soybean-pea small subunit precursor. The heat shock protein alone did not import into nor bind to chloroplasts. The binding of both the chimeric small-subunit-heat shock protein and the soybean-pea small subunit precursor to chloroplasts was physiologically significant, as shown by the fact that when chloroplasts with bound precursors were isolated, these bound precursors could subsequently be imported.
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Affiliation(s)
- T H Lubben
- Department of Botany, University of Wisconsin, Madison, WI 53706
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Fujimoto H, Taguchi JI, Imai Y, Ayabe S, Hashimoto H, Kobayashi H, Ogasawara K, Aizawa T, Yamakado M, Nagai R, Ohno M. Manganese superoxide dismutase polymorphism affects the oxidized low-density lipoprotein-induced apoptosis of macrophages and coronary artery disease. Eur Heart J 2007; 29:1267-74. [PMID: 17967822 DOI: 10.1093/eurheartj/ehm500] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AIMS Oxidative damage promotes atherosclerosis. Manganese superoxide dismutase (MnSOD) is an antioxidant enzyme localized in mitochondria. We investigated the associations of the MnSOD polymorphism (valine-to-alanine in the mitochondrial-targeting domain) with its activity in leukocytes, with macrophage apoptosis by oxidized low-density lipoprotein (oxLDL), and with coronary artery disease (CAD). METHODS AND RESULTS Blood samples were taken from 50 healthy subjects. The mitochondrial MnSOD activities in leukocytes were 542.4 +/- 71.6 U/mg protein (alanine/alanine, n = 2), 302.0 +/- 94.9 U/mg protein (alanine/valine, n = 12), and 134.0 +/- 67.1 U/mg protein (valine/valine, n = 36; P < 0.0001 for non-valine/valine vs. valine/valine). Macrophages were treated with oxLDL. After incubation, the percentages of apoptotic macrophages were 48.6 +/- 3.6% (alanine/alanine), 78.6 +/- 9.8% (alanine/valine), and 87.5 +/- 7.0% (valine/valine) (P < 0.0001, non-valine/valine vs. valine/valine). The association of the MnSOD polymorphism with CAD was investigated using blood samples collected from 498 CAD patients and 627 healthy subjects; the alanine allele was found to reduce the risk of CAD and acute myocardial infarction (AMI). CONCLUSION Our data indicate that the alanine variant of signal peptide increases the mitochondrial MnSOD activity, protects macrophages against the oxLDL-induced apoptosis, and reduces the risk of CAD and AMI.
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Affiliation(s)
- Hajime Fujimoto
- Department of Cardiovascular Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
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Getachew F, Gedamu L. Leishmania donovani iron superoxide dismutase A is targeted to the mitochondria by its N-terminal positively charged amino acids. Mol Biochem Parasitol 2007; 154:62-9. [PMID: 17524502 DOI: 10.1016/j.molbiopara.2007.04.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 04/03/2007] [Accepted: 04/11/2007] [Indexed: 11/19/2022]
Abstract
Many reports have shown that Leishmania species are susceptible to reactive oxygen species (ROS) and reactive nitrogen species (RNS)-mediated killing. The superoxide dismutase (SOD) is one of the antioxidant defense enzymes important for parasite survival through its detoxification of superoxide into hydrogen peroxide and oxygen. The mitochondria produce numerous superoxide radicals as a by-product of cellular respiration and hence targeting of SODs to the mitochondria is critical in maintaining healthy mitochondria. This study examines the characteristic determinants for mitochondrial localization of Leishmania donovani FeSODA. We show that FeSODA is localized to the mitochondria and that the N-terminal 31 amino acid extension is important for its localization. Interestingly, further dissection of the 31 amino acid extension revealed that the first 8 amino acids of the FeSODA protein are sufficient for targeting to the mitochondria. In addition, we found that the four basic amino acid residues contained within the N-terminal extension are also important for targeting. These studies highlight important features of mitochondrial targeting sequences in kinetoplastids.
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Affiliation(s)
- Fitsum Getachew
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada
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LEE JOHNJ, SOLDO ANTHONYT, REISSER WERNER, LEE MONICAJ, JEON KW, GÖRTZ HANSDIETER. The Extent of Algal and Bacterial Endosymbioses in Protozoa1,2. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1985.tb04034.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Levillain O, Hus-Citharel A, Garvi S, Peyrol S, Reymond I, Mutin M, Morel F. Ornithine metabolism in male and female rat kidney: mitochondrial expression of ornithine aminotransferase and arginase II. Am J Physiol Renal Physiol 2004; 286:F727-38. [PMID: 14871882 DOI: 10.1152/ajprenal.00315.2003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the kidney, l-ornithine is reabsorbed along the proximal convoluted tubule (PCT), transported by basolateral carriers, and produced by arginase II (AII). Here, the renal metabolic fate of l-ornithine was analyzed in male and female rats. Kidneys and renal zones were dissected and used for Western blot analysis, immunofluorescence, and electron microscopic studies. Ornithine aminotransferase (OAT) and AII were localized using specific antibodies. Ornithine oxidation was determined by incubating microdissected tubules with l-[1-14C] or l-[U-14C]ornithine in the presence or absence of energy-providing substrates. Ornithine decarboxylase (ODC) mRNAs were localized by in situ hybridization. The 48-kDa OAT protein was detected in male and female kidneys, but its level was fourfold higher in the latter. OAT relative distribution increased from the superficial cortex toward the outer medulla to reach its highest level. Almost all OAT protein was localized in cortical and medullary proximal straight tubules (CPST and OSPST, respectively). In proximal straight tubule (PST), AII protein distribution overlapped that of OAT. No gender difference in AII protein level was found. OAT and AII were colocalized within PST mitochondria. l-[1-14C]ornithine decarboxylation occurred in all tubules, but predominantly in proximal tubules. l-[1-14C]ornithine decarboxylation was enhanced when l-[1-14C]ornithine was given to tubules as the sole substrate. The use of l-[U-14C]ornithine demonstrated the complete oxidation of ornithine. In conclusion, the OAT gene was expressed more in female rat proximal tubules than in male. Because OAT and AII proteins overlapped in PST mitochondria, l-arginine-derived ornithine may be preferentially converted to l-glutamate, as proven by ornithine oxidation. However, the coexpression of ODC, glutamate decarboxylase, and glutamine synthetase in PST suggests that l-ornithine can also be metabolized to putrescine, GABA, and l-glutamine. The fate of l-ornithine may depend on the cellular context.
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Affiliation(s)
- Olivier Levillain
- Laboratoire de Physiopathologie Métabolique et Rénale, Faculté de Médecine Lyon R. T. H. Laennec, INSERM U 499, 7 ue G. Paradin, 69372 Lyon Cedex 08, France.
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Mitrunen K, Hirvonen A. Molecular epidemiology of sporadic breast cancer. The role of polymorphic genes involved in oestrogen biosynthesis and metabolism. Mutat Res 2003; 544:9-41. [PMID: 12888106 DOI: 10.1016/s1383-5742(03)00016-4] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The major known risk factors for female breast cancer are associated with prolonged exposure to increased levels of oestrogen. The predominant theory relates to effects of oestrogen on cell growth. Enhanced cell proliferation, induced either by endogenous or exogenous oestrogens, increases the number of cell divisions and thereby the possibility for mutation. However, current evidence also supports a role for oxidative metabolites, in particular catechol oestrogens, in the initiation of breast cancer. As observed in drug and chemical metabolism, there is considerable interindividual variability (polymorphism) in the conjugation pathways of both oestrogen and catechol oestrogens. These person-to-person differences, which are attributed to polymorphisms in the genes encoding for the respective enzymes, might define subpopulations of women with higher lifetime exposure to hormone-dependent growth promotion, or to cellular damage from particular oestrogens and/or oestrogen metabolites. Such variation could explain a portion of the cancer susceptibility associated with reproductive effects and hormone exposure. In this paper the potential role of polymorphic genes encoding for enzymes involved in oestrogen biosynthesis (CYP17, CYP19, and 17beta-HSD) and conversion of the oestrogen metabolites and their by-products (COMT, CYP1A1, CYP1B1, GSTM1, GSTM3, GSTP1, GSTT1 and MnSOD) in modulating individual susceptibility to breast cancer are reviewed. Although some of these low-penetrance genes appeared as good candidates for risk factors in the etiology of sporadic breast cancer, better designed and considerably larger studies than the majority of the studies conducted so far are evidently needed before any firm conclusions can be drawn.
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Affiliation(s)
- Katja Mitrunen
- Department of Industrial Hygiene and Toxicology, Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FIN-00250, Helsinki, Finland
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Abdullaev ZK, Bodrova ME, Chernyak BV, Dolgikh DA, Kluck RM, Pereverzev MO, Arseniev AS, Efremov RG, Kirpichnikov MP, Mokhova EN, Newmeyer DD, Roder H, Skulachev VP. A cytochrome c mutant with high electron transfer and antioxidant activities but devoid of apoptogenic effect. Biochem J 2002; 362:749-54. [PMID: 11879204 PMCID: PMC1222441 DOI: 10.1042/0264-6021:3620749] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A cytochrome c mutant lacking apoptogenic function but competent in electron transfer and antioxidant activities has been constructed. To this end, mutant species of horse and yeast cytochromes c with substitutions in the N-terminal alpha-helix or position 72 were obtained. It was found that yeast cytochrome c was much less effective than the horse protein in activating respiration of rat liver mitoplasts deficient in endogenous cytochrome c as well as in inhibition of H(2)O(2) production by the initial segment of the respiratory chain of intact rat heart mitochondria. The major role in the difference between the horse and yeast proteins was shown to be played by the amino acid residue in position 4 (glutamate in horse, and lysine in yeast; horse protein numbering). A mutant of the yeast cytochrome c containing K4E and some other "horse" modifications in the N-terminal alpha-helix, proved to be (i) much more active in electron transfer and antioxidant activity than the wild-type yeast cytochrome c and (ii), like the yeast cytochrome c, inactive in caspase stimulation, even if added in 400-fold excess compared with the horse protein. Thus this mutant seems to be a good candidate for knock-in studies of the role of cytochrome c-mediated apoptosis, in contrast with the horse K72R, K72G, K72L and K72A mutant cytochromes that at low concentrations were less active in apoptosis than the wild-type, but were quite active when the concentrations were increased by a factor of 2-12.
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Affiliation(s)
- Ziedulla Kh Abdullaev
- Laboratory of Spectral Analysis, M.M. Shemyakin and Y.A. Ovchinnikov Institute of Bioorganic Chemistry, Moscow 177871, Russia
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McIntyre P, Graf L, Mercer J, Peterson G, Hudson P, Hoogenraad N. A highly basic N-terminal extension of the mitochondrial matrix enzyme ornithine transcarbamylase from rat liver. FEBS Lett 2001; 177:41-6. [PMID: 6548714 DOI: 10.1016/0014-5793(84)80977-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have deduced the amino acid sequence of the N-terminal leader peptide of the mitochondrial enzyme ornithine transcarbamylase from a cDNA clone obtained from a rat liver cDNA library. The sequence is remarkable in being highly basic, having 4 arginine, 3 lysine and 1 histidine with no acidic residues in a total of 32 residues. The leader sequence has no extensive hydrophobic stretches, has 72% homology with the leader peptide of human ornithine transcarbamylase [1], and in terms of its basic character resembles the N-terminal extensions on a number of fungal mitochondrial [2-5] and pea chloroplast [6] proteins. Thus the basic nature of these leader peptides may constitute the signal for mitochondrial import.
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Kobayashi K, Iwasaki Y, Sasaki T, Nakamura K, Asahi T. Putative ammo-terminal presequence for β-subunit of plant mitochondrial F1ATPase deduced from the amino-terminal sequence of the mature subunit. FEBS Lett 2001. [DOI: 10.1016/0014-5793(86)80731-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Petit P, Diolez P, Muller P, Brown S. Binding of concanavalin A to the outer membrane of potato tuber mitochondria detected by flow cytometry. FEBS Lett 2001. [DOI: 10.1016/0014-5793(86)80215-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Montich GG. Partly folded states of bovine carbonic anhydrase interact with zwitterionic and anionic lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1468:115-26. [PMID: 11018657 DOI: 10.1016/s0005-2736(00)00250-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The acidic, partly folded states of bovine carbonic anhydrase II (BCAII) were used as an experimental system to study the interactions of partly denatured proteins with lipid membranes. The pH dependence of their interactions with palmitoyloleoyl phosphatidylcholine (POPC) and palmitoyloleoyl phosphatidylglycerol (POPG) membranes was studied. A filtration binding assay shows that acidic partly folded states of BCAII bind to POPC membranes. Fluorescence emission spectra from Trp residues of the bound protein are slightly shifted to shorter wavelength and can be quenched by a water-soluble quencher of fluorescence, indicating that the binding occurs without deep penetration of Trp residues into the membrane. The content of beta-structures of the protein in solution, as revealed by FT-IR spectroscopy, decreases in the partly folded states and the binding to POPC membrane occurs without further changes of secondary structure. In the presence of 0.1 M NaCl, a partly folded state self-aggregates and does not bind to POPC membrane. At acidic pH, BCAII binds to POPG membranes both at high and low ionic strength. The binding to the anionic lipid occurs with protein self-aggregation within the lipid-protein complexes and with changes in the secondary structure; large blue shifts in the fluorescence emission spectra and the decrease in the exposure to water-soluble acrylamide quencher of Trp fluorescence strongly suggest that BCAII penetrates the hydrocarbon domain in the POPG-protein complexes.
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Affiliation(s)
- G G Montich
- Centro de Investigaciones en Química Biológica de Córdoba, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Pabellón Argentina, Ciudad Universitaria, 5000, Córdoba, Argentina
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22
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Koo YK, Nandi D, Silverman RB. The multiple active enzyme species of gamma-aminobutyric acid aminotransferase are not isozymes. Arch Biochem Biophys 2000; 374:248-54. [PMID: 10666304 DOI: 10.1006/abbi.1999.1623] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Purified gamma-aminobutyric acid aminotransferase (GABA-AT) from pig brain under certain conditions gave a single band on 12% NaDodSO(4)-PAGE, whereas two or three distinct bands were observed on 7.5% native PAGE. These multiple active species were isolated by 5% preparative gel electrophoresis and characterized by N-terminal sequencing and MALDI-TOF mass spectrometry. The results indicate that these active enzyme species are not GABA-AT isozymes in pig brain, but are the products of proteolysis of the N-terminus of GABA-AT, differing by 3, 7, and 12 residues from the full sequence (as deduced from the cDNA), respectively. Conditions for obtaining the nontruncated GABA-AT were found, and the potential cause for the proteolysis was determined. It was found that Na(2)EDTA inhibits the N-terminal cleavage during GABA-AT preparation from pig brain. The presence of Triton X-100 in the homogenization step is partially responsible for this proteolysis, and Mn(2+) strongly enhances the protease activity, suggesting the presence of a membrane-bound matrix metalloprotease that causes the N-terminal cleavage.
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Affiliation(s)
- Y K Koo
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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23
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Hiroi S, Harada H, Nishi H, Satoh M, Nagai R, Kimura A. Polymorphisms in the SOD2 and HLA-DRB1 genes are associated with nonfamilial idiopathic dilated cardiomyopathy in Japanese. Biochem Biophys Res Commun 1999; 261:332-9. [PMID: 10425186 DOI: 10.1006/bbrc.1999.1036] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To reveal genetic risk factors of nonfamilial idiopathic cardiomyopathy (IDC) in Japanese, polymorphisms in the SOD2 and HLA-DRB1 genes were investigated in 86 patients and 380 healthy controls. There was a significant excess of homozygotes for the V allele [Val versus Ala (A allele), a polymorphism in the leader peptide of manganese superoxide dismutase at position 16] of the SOD2 gene in the patients compared with the controls (87.2% versus 74.7%, odds ratio = 2.30, p = 0.013, pc < 0.03), and a significant increase in the frequency of HLA-DRB1*1401 in the patients was confirmed (14.0% vs 4.5%, odds ratio = 3.46, p = 0.001, pc < 0.03). A two-locus analysis suggested that these two genetic markers (SOD2-VV genotype and DRB1*1401) may play a synergistic role in controlling the susceptibility to nonfamilial IDC. In addition, processing efficiency of Val-type SOD2 leader peptide in the presence of mitochondria was siginificantly lower than that of the Ala-type by 11 +/- 4%, suggesting that this lower processing efficiency was in part an underlying mechanism of the association between the SOD2-VV genotype and nonfamilial IDC.
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Affiliation(s)
- S Hiroi
- Division of Adult Diseases, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, 101, Japan
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24
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Freeman FM, Young IG. Chloramphenicol-induced amnesia for passive avoidance training in the day-old chick. Neurobiol Learn Mem 1999; 71:80-93. [PMID: 9889074 DOI: 10.1006/nlme.1998.3867] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The antibiotic chloramphenicol, an inhibitor of mitochondrial protein synthesis, was used to investigate the time-related changes in protein synthesis following passive avoidance training in the day-old chick (white leghorn-black Australorp). Retention of memory for this simple learning task is known to be prevented by an inhibitor of cytosolic protein synthesis, anisomycin, in a biphasic manner, with the first phase of sensitivity occurring up to 90 min post-training and the second phase between 4 and 5 h post-training (Freeman, Rose, & Scholey, 1995). Birds received bilateral intracranial injections of chloramphenicol (10 microl/hemisphere of a 7.4 mM solution) at various times relative to training and were tested 24 h later. This report shows that at the second phase of anisomycin susceptibility there was a chloramphenicol-sensitive period (5 h post-training) which had an onset time less than 1 h after injection. The effect of chloramphenicol appears not to be due to the mitochondria being energetically compromised since intracranial injections of an uncoupler of mitochondrial oxidative phosphorylation, 2,4-dinitrophenol (0.1 mM), did not disrupt memory formation when injected 5 h after training, even though it did cause amnesia when injected at the earlier time point of 20 min post-training. These results are discussed in the context of what is already known about memory formation in the day-old chick.
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Affiliation(s)
- F M Freeman
- John Curtin School of Medical Research, The Australian National University, Canberra, ACT, 0200,
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25
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Fabregat ME, Usac EF, Franco C, Enrich C, Malaisse WJ, Gomis R, Enric C. Site-directed mutations of the FAD-linked glycerophosphate dehydrogenase gene impairs the mitochondrial anchoring of the enzyme in transfected COS-7 cells. Biochem Biophys Res Commun 1998; 252:173-7. [PMID: 9813165 DOI: 10.1006/bbrc.1998.9632] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
COS-7 cells were transfected with the green fluorescent protein (GFP) of Aequorea victoria, human mitochondrial FAD-linked glycerophosphate dehydrogenase (mGDH), a mGDHwt-EGFP construct, or two mutant mGDH-proteins fused with EGFP. The site of mutation was selected to affect cationic amino acids in the peptide signal sequence currently believed to play a key role in the subcellular distribution of mitochondrial proteins. All proteins were suitably expressed in the COS-7 cells. However, an increase in mGDH enzymatic activity above the control value in non-transfected COS-7 cell homogenates was only observed in cells transfected with mGDH, indicating that the catalytic activity of mGDH was masked in fused proteins. Confocal microscopy documented that, in the cells transfected with the mGDHwt-EGFP construct, the fusion protein was located exclusively in mitochondria, this contrasting with the nuclear labelling of cells expressing the green fluorescent protein alone. The mitochondrial anchoring of the mutated mGDH fused protein was altered, this alteration being most obvious in the mGDH313233-EGFP mutant. These findings raise the idea that a conformation change of the mGDH protein, as resulting from either an inherited or acquired alteration of its amino acid sequence, may affect its subcellular distribution and, hence, modify its immunogenic potential.
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Affiliation(s)
- M E Fabregat
- Medical Department, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clinic, Barcelona, Spain
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26
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Shen BW, Hennig M, Hohenester E, Jansonius JN, Schirmer T. Crystal structure of human recombinant ornithine aminotransferase. J Mol Biol 1998; 277:81-102. [PMID: 9514741 DOI: 10.1006/jmbi.1997.1583] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ornithine aminotransferase (OAT), a pyridoxal-5'-phosphate dependent enzyme, catalyses the transfer of the delta-amino group of L-ornithine to 2-oxoglutarate, producing L-glutamate-gamma-semialdehyde, which spontaneously cyclizes to pyrroline-5-carboxylate, and L-glutamate. The crystal structure determination of human recombinant OAT is described in this paper. As a first step, the structure was determined at low resolution (6 A) by molecular replacement using the refined structure of dialkylglycine decarboxylase as a search model. Crystallographic phases were then refined and extended in a step-wise fashion to 2.5 A by cyclic averaging of the electron density corresponding to the three monomers within the asymmetric unit. Interpretation of the resulting map was straightforward and refinement of the model resulted in an R-factor of 17.1% (Rfree=24.3%). The success of the procedure demonstrates the power of real-space molecular averaging even with only threefold redundancy. The alpha6-hexameric molecule is a trimer of intimate dimers with a monomer-monomer interface of 5500 A2 per subunit. The three dimers are related by an approximate 3-fold screw axis with a translational component of 18 A. The monomer fold is that of a typical representative of subgroup 2 aminotransferases and very similar to those described for dialkylglycine decarboxylase from Pseudomonas cepacia and glutamate-1-semialdehyde aminomutase from Synechococcus. It consists of a large domain that contributes most to the subunit interface, a C-terminal small domain most distant to the 2-fold axis and an N-terminal region that contains a helix, a loop and a three stranded beta-meander embracing a protrusion in the large domain of the second subunit of the dimer. The large domain contains the characteristic central seven-stranded beta-sheet (agfedbc) covered by eight helices in a typical alpha/beta fold. The cofactor pyridoxal-5'-phosphate is bound through a Schiff base to Lys292, located in the loop between strands f and g. The C-terminal domain includes a four-stranded antiparallel beta-sheet in contact with the large domain and three further helices at the far end of the subunit. The active sites of the dimer lie, about 25 A apart, at the subunit and domain interfaces. The conical entrances are on opposite sides of the dimer. In the active site, R180, E235 and R413 are probable substrate binding residues. Structure-based sequence comparisons with related transaminases in this work support that view. In patients suffering from gyrate atrophy, a recessive hereditary genetic disorder that can cause blindness in humans, ornithine aminotransferase activity is lacking. A large number of frameshift and point mutations in the ornithine aminotransferase gene have been identified in such patients. Possible effects of the various point mutations on the structural stability or the catalytic competence of the enzyme are discussed in light of the three-dimensional structure.
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Affiliation(s)
- B W Shen
- Department of Structural Biology, Biozentrum, Basel, CH-4056, Switzerland
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27
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Abstract
Recent progress in studies on apoptosis has revealed that cytochrome c is a pro-apoptotic factor. It is released from its places on the outer surface of the inner mitochondrial membrane at early steps of apoptosis and, combining with some cytosolic proteins, activates conversion of the latent apoptosis-promoting protease pro-caspase-9 to its active form. Cytochrome c release can be initiated by the pro-apoptotic protein Bax. This process is blocked by the anti-apoptotic proteins Bcl-2 and Bcl-xL. The role of cytochrome c in apoptosis may be understood within the framework of the concept assuming that the evolutionary primary function of apoptosis was to purify tissues from ROS-overproducing cells. In this context, the pro-apoptosis activity of cytochrome c might represent one of the anti-oxidant functions inherent in this cytochrome. Among other cytochrome c-linked antioxidant mechanisms, the following systems can be indicated. (1) Cytochrome c released from the inner mitochondrial membrane to the intermembrane space can operate as an enzyme oxidizing O2.- back to O2. The reduced cytochrome c is oxidized by cytochrome oxidase (or in yeasts and bacteria, by cytochrome c peroxidase). (2) The intermembrane cytochrome c can activate the electron transport chain in the outer mitochondrial membrane. This bypasses the initial and middle parts of the main respiratory chain, which produce, as a rule, the major portion of ROS in the cell. (3) The main respiratory chain losing its cytochrome c is inhibited in such a fashion that antimycin-like agents fail to stimulate ROS production.
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Affiliation(s)
- V P Skulachev
- Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
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28
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Abstract
5-Aminolevulinic acid (ALA), a universal precursor of tetrapyrrole compounds can be synthesized by two pathways: the C5 (glutamate) pathway and ALA synthase. From the phylogenetic distribution it is shown that distribution of ALA synthase is restricted to the alpha subclass of purple bacteria in prokaryotes, and further distributed to mitochondria of eukaryotes. The monophyletic origin of bacterial and eukaryotic ALA synthase is shown by sequence analysis of the enzyme. Evolution of ALA synthase in the alpha subclass of purple bacteria is discussed in relation to the energy-generating and biosynthetic devices in subclasses of this bacteria.
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Affiliation(s)
- T Oh-hama
- Research Institute of Evolutionary Biology, Tokyo, Japan
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Medeiros DM, Shiry L, Samelman T. Cardiac nuclear encoded cytochrome c oxidase subunits are decreased with copper restriction but not iron restriction: gene expression, protein synthesis and heat shock protein aspects. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART A, PHYSIOLOGY 1997; 117:77-87. [PMID: 9185337 DOI: 10.1016/s0300-9629(96)00365-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Hearts from rats fed a copper-deficient (Cu-) diet have decreased levels of nuclear-encoded peptides of cytochrome c oxidase (CCO). Studies were conducted to determine whether iron deficiency would lead to a similar finding, whether mRNA transcripts and the chaperonin heat shock proteins (HSP) 60 and 70 from hearts of Cu- rats were decreased as compared with copper-adequate controls and whether synthesis of mitochondrial and nuclear encoded peptides differed as affected by diet copper. In study 1, weanling rats were assigned to one of three groups (n = 6 in each group): (1) control copper and iron adequate fed rats; (2) Cu- rats and (3) iron-deficient (Fe-) rats. Western blotting of nonmyofibrillar cardiac proteins revealed that the nuclear encoded peptides of CCO from the Cu- rats were markedly decreased as compared with control and Fe- rats. Mitochondrial encoded subunits did not appear to differ by treatment groups. Iron-deficient rats had similar nuclear encoded peptide levels as those of controls. In study 2, mRNA transcripts from Cu- (n = 4) and control copper adequate (n = 4) rats did not appear to differ for subunits II and IV, which correspond to mitochondrial and nuclear encoded subunits, respectively. In study 3, levels of HSP 60 and 70 from hearts of Cu- rats (n = 3) did not differ from Cu+ rats (n = 3). In study 4, infusion of 3H-(4,5)-leucine into the hearts of Cu+ and Cu- rats suggested there was no difference in synthesis of the nuclear encoded peptides by copper status and some indication there was enhanced breakdown of the nuclear encoded peptides among the Cu- rats. As expected, more isotope was incorporated into the mitochondria of Cu- rats than Cu+ rats. These results demonstrate an independent effect of copper upon the apparent decrease in the nuclear encoded subunits of CCO, the effect of copper upon the CCO subunits is probably post-transcriptional and that translocation of the nuclear encoded subunits from the ribosomes to the mitochondria via the chaperonin proteins is not a primary defect in explaining these observations in hearts from Cu- rats and synthesis of the nuclear encoded subunits of CCO in not impaired in copper deficiency.
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Affiliation(s)
- D M Medeiros
- Department of Human Nutrition and Food Management, Ohio State University, Columbus 43210-1295, USA
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30
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Jalili T, Medeiros D, Prochaska L. Alterations in cardiac cytochrome C oxidase, but not in laminin and fibronectin, are observed within three weeks of copper restriction in rats: Implications for cardiac hypertrophy. Nutr Res 1997. [DOI: 10.1016/s0271-5317(97)00013-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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31
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Sasaki H, Kurioka S, Fukata H, Ohoki T, Arai H, Suzuki T. Isolation of intramitochondrial helical filaments appearing in outer compartment of mitochondria. Anat Rec (Hoboken) 1995; 241:149-54. [PMID: 7710131 DOI: 10.1002/ar.1092410202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Packets of helical filaments have been observed in the outer compartment of occasional mitochondria in many cell types in a variety of animals. The composition and function of these intramitochondrial helical filaments (IMHF) are unknown. METHODS IMHF were induced in a hepatic mitochondria by administration of ethanol in the drinking water of rats. Hepatic mitochondria were isolated and ruptured by osmotic shock, releasing the IMHF. To purify these structures, the IMHF-containing supernatant was further fractionated by ammonium sulfate precipitation, a 50-60% solution of this reagent being the most effective in this regard. Isolated IMHF were examined by electron microscopy and were analyzed by SDS-PAGE. RESULTS Isolated IMHF closely resembled their in situ counterparts: they had a right-handed helical structure with a 16 nm pitch. SDS-PAGE analysis revealed that they contained three polypeptides with molecular weight of 135, 98, and 53 kD, respectively. CONCLUSIONS These observations will stand as a baseline for comparisons with IMHF that occur naturally or that are induced in other cell types by other kinds of experimental manipulation.
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Affiliation(s)
- H Sasaki
- Division of Morphology, Jikei University School of Medicine, Japan
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32
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Rat very-long-chain acyl-CoA dehydrogenase, a novel mitochondrial acyl-CoA dehydrogenase gene product, is a rate-limiting enzyme in long-chain fatty acid beta-oxidation system. cDNA and deduced amino acid sequence and distinct specificities of the cDNA-expressed protein. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32278-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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33
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Benz R. Permeation of hydrophilic solutes through mitochondrial outer membranes: review on mitochondrial porins. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1197:167-96. [PMID: 8031826 DOI: 10.1016/0304-4157(94)90004-3] [Citation(s) in RCA: 347] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- R Benz
- Lehrstuhl für Biotechnologie, Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Germany
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34
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Lin B, Shane B. Expression of Escherichia coli folylpolyglutamate synthetase in the Chinese hamster ovary cell mitochondrion. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)36940-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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35
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Mosbaugh DW, Bennett SE. Uracil-excision DNA repair. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1994; 48:315-70. [PMID: 7938553 DOI: 10.1016/s0079-6603(08)60859-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- D W Mosbaugh
- Department of Agricultural Chemistry, Biochemistry and Biophysics, Oregon State University, Corvallis 97331
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36
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Abstract
From the point of view of a preprotein, escaping from the cytosol into a specific organelle must seem an arduous, almost impossible task. How is it that preproteins resist the temptation to fold prematurely, to avoid the multiple membrane surfaces in the cell, and manage instead to enter only the translocation apparatus of a single organelle?
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Affiliation(s)
- T Lithgow
- Department of Biochemistry, La Trobe University, Bundoora, Australia
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37
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Mitchell G, Robert M, Hruz P, Wang S, Fontaine G, Behnke C, Mende-Mueller L, Schappert K, Lee C, Gibson K. 3-Hydroxy-3-methylglutaryl coenzyme A lyase (HL). Cloning of human and chicken liver HL cDNAs and characterization of a mutation causing human HL deficiency. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53620-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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38
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Analysis of the perturbation of phospholipid model membranes by rhodanese and its presequence. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)35749-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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39
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Stocco DM. Further evidence that the mitochondrial proteins induced by hormone stimulation in MA-10 mouse Leydig tumor cells are involved in the acute regulation of steroidogenesis. J Steroid Biochem Mol Biol 1992; 43:319-33. [PMID: 1327068 DOI: 10.1016/0960-0760(92)90167-h] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In previous studies we and others have described several mitochondrial proteins which are synthesized in response to acute hormone stimulation in several steroidogenic tissues. In both MA-10 mouse Leydig tumor cells and primary cultures of rat adrenal cortex cells, these proteins consist of a family of 37 kilodalton (kDa) and 32 kDa precursor forms and fully processed forms which are 30 kDa in molecular weight. The nature of the appearance of these proteins and their subcellular localization to the mitochondria, the site of the rate limiting step in steroidogenesis, has led to the speculation that they may be involved in the acute regulation of steroidogenesis. In the present study we have taken advantage of another steroidogenic cell, the R2C rat Leydig tumor cell, to perform studies which further indicate that these mitochondrial proteins are involved in the regulation of steroidogenesis. Unlike the MA-10 cell which requires hormone stimulation for steroid production, the R2C cell is a constitutive progesterone producer whose steroid production cannot be further increased with hormone stimulation. We have shown that the R2C cell line is less sensitive to the inhibition of steroid production by the metal chelator orthophenanthroline (OP) than is the MA-10 cell. We have demonstrated that progesterone production and the 30 kDa mitochondrial proteins remain present in the R2C cells at a concentration of OP which completely inhibits progesterone production and totally eliminates the 30 kDa proteins in MA-10 cells. As further evidence for the role of these proteins in steroidogenic regulation, we have isolated several revertants of the R2C parent (P) cell line which have lost the ability to synthesize progesterone constitutively, but which can be stimulated to synthesize this steroid by trophic hormone and cAMP analog. In these revertants, designated (R), the normally constitutively present 30 kDa proteins are greatly decreased compared to controls, but reappear in large amounts following hormone stimulation. Taken together, these data provide further evidence that the 30 kDa mitochondrial proteins are involved in the acute regulation of steroidogenesis in Leydig cells.
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Affiliation(s)
- D M Stocco
- Department of Biochemistry and Molecular Biology, Texas Tech University Health Sciences Center, Lubbock 79430
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40
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Nolan DP, Voorheis HP. The mitochondrion in bloodstream forms of Trypanosoma brucei is energized by the electrogenic pumping of protons catalysed by the F1F0-ATPase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 209:207-16. [PMID: 1327770 DOI: 10.1111/j.1432-1033.1992.tb17278.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Bloodstream forms of Trypanosoma brucei were found to maintain a significant membrane potential across their mitochondrial inner membrane (delta psi m) in addition to a plasma membrane potential (delta psi p). Significantly, the delta psi m was selectively abolished by low concentrations of specific inhibitors of the F1F0-ATPase, such as oligomycin, whereas inhibition of mitochondrial respiration with salicylhydroxamic acid was without effect. Thus, the mitochondrial membrane potential is generated and maintained exclusively by the electrogenic translocation of H+, catalysed by the mitochondrial F1F0-ATPase at the expense of ATP rather than by the mitochondrial electron-transport chain present in T. brucei. Consequently, bloodstream forms of T. brucei cannot engage in oxidative phosphorylation. The mitochondrial membrane potential generated by the mitochondrial F1F0-ATPase in intact trypanosomes was calculated after solving the two-compartment problem for the uptake of the lipophilic cation, methyltriphenylphosphonium (MePh3P+) and was shown to have a value of approximately 150 mV. When the value for the delta psi m is combined with that for the mitochondrial pH gradient (Nolan and Voorheis, 1990), the mitochondrial proton-motive force was calculated to be greater than 190 mV. It seems likely that this mitochondrial proton-motive force serves a role in the directional transport of ions and metabolites across the promitochondrial inner membrane during the bloodstream stage of the life cycle, as well as promoting the import of nuclear-encoded protein into the promitochondrion during the transformation of bloodstream forms into the next stage of the life cycle of T. brucei.
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Affiliation(s)
- D P Nolan
- Department of Biochemistry, Trinity College, Dublin, Ireland
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41
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Bruch MD, Hoyt DW. Conformational analysis of a mitochondrial presequence derived from the F1-ATPase beta-subunit by CD and NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1159:81-93. [PMID: 1390913 DOI: 10.1016/0167-4838(92)90078-r] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Previous studies on mitochondrial targeting presequences have indicated that formation of an amphiphillic helix may be required for efficient targeting of the precursor protein into mitochondria, but the structural details are not well understood. We have used CD and NMR spectroscopy to characterize in detail the structure of a synthetic peptide corresponding to the presequence for the beta-subunit of F1-ATPase, a mitochondrial matrix protein. Although this peptide is essentially unstructured in water, alpha-helix formation is induced when the peptide is placed in structure-promoting environments, such as SDS micelles or aqueous trifluoroethanol (TFE). In 50% TFE (by volume), the peptide is in dynamic equilibrium between random coil and alpha-helical conformations, with a significant population of alpha-helix throughout the entire peptide. The helix is somewhat more stable in the N-terminal part of the presequence (residues 4-10), and this result is consistent with the structure proposed previously for the presequence of another mitochondrial matrix protein, yeast cytochrome oxidase subunit IV. Addition of increasing amounts of TFE causes the alpha-helical content to increase even further, and the TFE titration data for the presequence peptide of the F1-ATPase beta-subunit are not consistent with a single, cooperative transition from random coil to alpha-helix. There is evidence that helix formation is initiated in two different regions of the peptide. This result helps to explain the redundancy of the targeting information contained in the presequence for the F1-ATPase beta-subunit.
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Affiliation(s)
- M D Bruch
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas
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42
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Kadenbach B, Reimann A. Chapter 10 Cytochrome c oxidase: tissue-specific expression of isoforms and regulation of activity. MOLECULAR MECHANISMS IN BIOENERGETICS 1992. [DOI: 10.1016/s0167-7306(08)60178-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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43
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Ono H, Tuboi S. Purification of 52 kDa protein: a putative component of the import machinery for the mitochondrial protein-precursor in rat liver. Biochem Biophys Res Commun 1991; 180:450-4. [PMID: 1930237 DOI: 10.1016/s0006-291x(05)81314-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A protein having a molecular mass of 52 kDa was purified to homogeneity from solubilized mitochondrial membrane proteins by affinity column chromatography using the synthetic presequence of ornithine aminotransferase (OAT) as the ligand. This 52 kDa protein was specifically bound to the affinity column and eluted with 1 mM OAT-presequence, indicating that it recognized the presequence and bound to it specifically. Anti-52 kDa protein Fab fragments specifically inhibited the import of OAT-precursor into mitochondria, showing that the 52 kDa protein plays an essential role in this process. These results suggest that 52 kDa protein is a component of the import machinery of the mitochondrial protein-precursor in the mitochondrial membrane.
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Affiliation(s)
- H Ono
- Department of Biochemistry, Yamagata University School of Medicine, Japan
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44
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Stocco D, Sodeman T. The 30-kDa mitochondrial proteins induced by hormone stimulation in MA-10 mouse Leydig tumor cells are processed from larger precursors. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)55053-5] [Citation(s) in RCA: 189] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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45
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De Loecker P, Fuller BJ, De Loecker W. The effects of cryopreservation on protein synthesis and membrane transport in isolated rat liver mitochondria. Cryobiology 1991; 28:445-53. [PMID: 1752132 DOI: 10.1016/0011-2240(91)90053-q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Protein synthesizing activity and membrane transport were examined in fresh and cryopreserved isolated rat liver mitochondria. In the presence of 0.6, 1.2, and 1.8 M final concentrations of dimethyl sulfoxide (Me2SO), both metabolic parameters were considerably inhibited in the fresh samples and even more inhibited in the cryopreserved specimens. However, simple exposure to this penetrating cryoprotectant, followed by its subsequent removal by washing, did not seem to affect significantly the examined functions. When different freeze-thaw regimes were investigated, it was observed that optimal recovery of protein synthesis and membrane transport functions were obtained when fast freezing took place in the absence of Me2SO.
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Affiliation(s)
- P De Loecker
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit te Leuven, Belgium
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46
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Aqua MS, Bachman NJ, Lomax MI, Grossman LI. Characterization and expression of a cDNA specifying subunit VIIc of bovine cytochrome c oxidase. Gene 1991; 104:211-7. [PMID: 1655579 DOI: 10.1016/0378-1119(91)90252-7] [Citation(s) in RCA: 5] [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
We have isolated a cDNA that encodes subunit VIIc of bovine cytochrome c oxidase (COX VIIc). The 325-bp cDNA contains sequences encoding the mature 47-amino acid (aa) polypeptide and a 16-aa presequence. The deduced aa sequence of the processed polypeptide is identical to that of the heart protein determined by aa sequencing. Northern-blot analysis reveals a single 525-nucleotide (nt) transcript in all tissues examined, whose levels vary with the corresponding respiratory activities in different tissues; thus, no evidence for isoforms of COX VIIc is seen in adult tissues. Southern-blot analysis of bovine genomic DNA digested with three different restriction enzymes reveals several bands that hybridize with the cDNA. We present here the sequence of one genomic region that contains a processed gene encoding COX VIIc. The genomic and cDNA nt sequences are 99% identical throughout the 189-bp open reading frame; the deduced aa sequences are identical. The sequence of the genomic clone suggests that the cDNA terminates prematurely at an EcoRI site in the 3'-untranslated region. We have compared COX VIIc cDNAs from cow, human and mouse, and find the presequence similarity among them to be 100% at the aa level.
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Affiliation(s)
- M S Aqua
- Department of Molecular Biology and Genetics, Wayne State University School of Medicine, Detroit, MI 48201
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47
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48
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Inoue I, Nagase H, Kishi K, Higuti T. ATP-sensitive K+ channel in the mitochondrial inner membrane. Nature 1991; 352:244-7. [PMID: 1857420 DOI: 10.1038/352244a0] [Citation(s) in RCA: 528] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mitochondria take up and extrude various inorganic and organic ions, as well as larger substances such as proteins. The technique of patch clamping should provide real-time information on such transport and on energy transduction in oxidative phosphorylation. It has been applied to detect microscopic currents from mitochondrial membranes and conductances of ion channels in the 5-1,000 pS range in the outer and inner membranes. These pores are not, however, selective for particular ions. Here we use fused giant mitoplasts prepared from rat liver mitochondria to identify a small conductance channel highly selective for K+ in the inner mitochondrial membrane. This channel can be reversibly inactivated by ATP applied to the matrix side under inside-out patch configuration; it is also inhibited by 4-aminopyridine and by glybenclamide. The slope conductance of the unitary currents measured at negative membrane potentials was 9.7 +/- 1.0 pS (mean +/- s.d., n = 6) when the pipette solution contained 100 mM K+ and the bathing solution 33.3 mM K+. Our results indicate that mitochondria depolarize by generating a K+ conductance when ATP in the matrix is deficient.
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Affiliation(s)
- I Inoue
- Institute for Enzyme Research, Tokushima University, Japan
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49
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Villa RF, Turpeenoja L, Magrì G, Gorini A, Ragusa N, Giuffrida-Stella AM. Effect of hypoxia on mitochondrial protein composition of cerebral cortex during aging. Neurochem Res 1991; 16:821-6. [PMID: 1944772 DOI: 10.1007/bf00965692] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effect of hypoxia on the protein composition of mitochondria from cerebral cortex of rats at 4, 12, and 24 months of age was investigated. The proteins were separated by electrophoresis on SDS polyacrylamide gels and the percent content was evaluated by measuring the optical density of the stained gels. The results demonstrate that hypoxic treatment causes a decrease in the amount of some proteins as follows: the 90 and the 16 kDa Mw proteins at 4 months; the 82 and the 79 kDa Mw proteins at 24 months; the 52-49, 35 and 20 kDa at all ages investigated; the 44 kDa protein at 4 and 12 months and the 28 kDa protein at 4 and 24 months of age. Our results show that hypoxic conditions affect mitochondrial protein composition to a greater extent than aging alone.
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Affiliation(s)
- R F Villa
- Institute of Pharmacology, Faculty of Science, University of Pavia, Italy
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50
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Genetics and Molecular Biology of Neurospora crassa. ADVANCES IN GENETICS 1991. [DOI: 10.1016/s0065-2660(08)60106-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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