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Couchet M, Breuillard C, Corne C, Rendu J, Morio B, Schlattner U, Moinard C. Ornithine Transcarbamylase - From Structure to Metabolism: An Update. Front Physiol 2021; 12:748249. [PMID: 34658931 PMCID: PMC8517447 DOI: 10.3389/fphys.2021.748249] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 09/07/2021] [Indexed: 12/30/2022] Open
Abstract
Ornithine transcarbamylase (OTC; EC 2.1.3.3) is a ubiquitous enzyme found in almost all organisms, including vertebrates, microorganisms, and plants. Anabolic, mostly trimeric OTCs catalyze the production of L-citrulline from L-ornithine which is a part of the urea cycle. In eukaryotes, such OTC localizes to the mitochondrial matrix, partially bound to the mitochondrial inner membrane and part of channeling multi-enzyme assemblies. In mammals, mainly two organs express OTC: the liver, where it is an integral part of the urea cycle, and the intestine, where it synthesizes citrulline for export and plays a major role in amino acid homeostasis, particularly of L-glutamine and L-arginine. Here, we give an overview on OTC genes and proteins, their tissue distribution, regulation, and physiological function, emphasizing the importance of OTC and urea cycle enzymes for metabolic regulation in human health and disease. Finally, we summarize the current knowledge of OTC deficiency, a rare X-linked human genetic disorder, and its emerging role in various chronic pathologies.
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Affiliation(s)
- Morgane Couchet
- Université Grenoble Alpes, Inserm U1055, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France
| | - Charlotte Breuillard
- Université Grenoble Alpes, Inserm U1055, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France
| | | | - John Rendu
- Centre Hospitalier Université Grenoble Alpes, Grenoble, France
| | - Béatrice Morio
- CarMeN Laboratory, INSERM U1060, INRAE U1397, Lyon, France
| | - Uwe Schlattner
- Université Grenoble Alpes, Inserm U1055, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France.,Institut Universitaire de France, Paris, France
| | - Christophe Moinard
- Université Grenoble Alpes, Inserm U1055, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France
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MIURA S, MORI M, AMAYA Y, TATIBANA M. A Mitochondria1 Protease that Cleaves the Precursor of Ornithine Carbamoyltransferase. ACTA ACUST UNITED AC 2005. [DOI: 10.1111/j.1432-1033.1982.tb06487.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ye X, Zimmer KP, Brown R, Pabin C, Batshaw ML, Wilson JM, Robinson MB. Differences in the human and mouse amino-terminal leader peptides of ornithine transcarbamylase affect mitochondrial import and efficacy of adenoviral vectors. Hum Gene Ther 2001; 12:1035-46. [PMID: 11399226 DOI: 10.1089/104303401750214267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mouse models of ornithine transcarbamylase (OTC) deficiency are being used to test the efficacy of viral vectors as possible vehicles for gene therapy. However, it has been demonstrated that virus containing the human OTC cDNA failed to express functional OTC enzyme in the recipient animals. Because functional OTC is assembled as a homotrimer in the mitochondria, there are at least two possible explanations for these results. Either endogenous mutant protein coassembles with the human OTC and has a "dominant-negative effect," or the human version of the protein is not appropriately imported or processed in the mouse mitochondria. To test the importance of processing, which in rodents is thought to depend on the leader peptide, adenoviral vectors containing chimeric OTC cDNAs were prepared. These vectors were evaluated in the OTC-deficient sparse fur mouse models. Although comparable levels of transgene expression were observed in all groups of mice, the only mice that had high levels of OTC activity and mitochondrial OTC immunoreactivity were those mice injected with the vectors containing the mouse leader peptide (mouse OTC and a mouse-human chimera of OTC). To address possible dominant-negative effects, adenoviruses containing mutant human or mouse OTC cDNAs were prepared and evaluated in cell lines or normal C3H mice, respectively. No inhibition of normal OTC activity was observed in either model system. Together, these studies provide no evidence of a dominant-negative effect and suggest that the human and rodent enzymes responsible for transporting of OTC and possibly other mitochondrial proteins have different specificity.
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Affiliation(s)
- X Ye
- Children's National Medical Center and Department of Pediatrics, The George Washington University, Washington, DC 20010, USA.
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Viglio S, Valentini G, Zanaboni G, Cetta G, De Gregorio A, Iadarola P. Rapid detection of ornithine transcarbamylase activity by micellar electrokinetic chromatography. Electrophoresis 1999; 20:138-44. [PMID: 10065970 DOI: 10.1002/(sici)1522-2683(19990101)20:1<138::aid-elps138>3.0.co;2-v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A quantitative ultraviolet detection method for determining ornithine transcarbamylase (OTC-ase) activity using micellar electrokinetic chromatography (MEKC) is described. The method is based on the direct determination of citrulline formed upon enzymatic reaction. Using a background electrolyte consisting of 35 mM sodium tetraborate, pH 9.3, containing 65 mM sodium dodecyl sulfate (SDS), the peak of citrulline in the electropherogram was easily identified and integrated. This allowed us to determine the rate of formation of the reaction product and to calculate the kinetic parameter Km of the OTC-ase investigated. The capillary electrophoretic method developed was applied to the determination of OTC-ase activity in plasma samples for citrulline in the nanogram range.
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Affiliation(s)
- S Viglio
- Dipartimento di Biochimica A. Castellani, Università di Pavia, Italy
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5
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Mitochondrial import and processing of mutant human ornithine transcarbamylase precursors in cultured cells. Mol Cell Biol 1989. [PMID: 3244350 DOI: 10.1128/mcb.8.12.5150] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have investigated mitochondrial import and processing of the precursor for human ornithine transcarbamylase (OTC; carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) in HeLa cells stably transformed with cDNA sequences encoding OTC precursors carrying mutations in their leader peptides. The mutant precursors studied included two with amino acid substitutions in the 32-amino-acid leader peptide (glycine for arginine at position 23, designated gly23; glycines for arginines at positions 15, 23, and 26, designated gly15,23,26) and two with deletions (deletion of residues 8 to 22, designated d8-22; deletion of residues 17 to 32, designated N16). Specific immunoprecipitation with anti-OTC antiserum of extracts of L-[35S]methionine-labeled cells expressing these mutations yielded only precursor species; neither mature nor intermediate-size OTC subunits were observed. Fractionation of radiolabeled cells, however, revealed important differences among the various mutants: the gly23 precursor was associated with mitochondria and was not detected in the cytosol; the d8-22 and N16 precursors were found with both the mitochondrial fraction and the cytosol; only the gly15,23,26 precursor was detected exclusively in the cytosol. A large fraction of each of the mitochondrially associated OTC species was in a trypsin-protected compartment. In particular, the gly23 precursor behaved in trypsin protection and mitochondrial fractionation studies in a manner consistent with its translocation into the mitochondrial matrix. On the other hand, the lack of binding of the gly23 protein to a delta-N-phosphonoacetyl-L-ornithine affinity column, which specifically recognizes active OTC enzyme, indicated that, despite its intramitochondrial location, the mutant protein did not assemble into the normal, active trimer. Further, the gly23 mutant precursor was unstable within the mitochondria and was degraded with a t1/2 of less further than 4 h. Thus, we have shown that, in intact HeLa cells, cleavage of the OTC leader peptide is not required for translocation into mitochondria, but is required for assembly into active enzyme.
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Isaya G, Fenton WA, Hendrick JP, Furtak K, Kalousek F, Rosenberg LE. Mitochondrial import and processing of mutant human ornithine transcarbamylase precursors in cultured cells. Mol Cell Biol 1988; 8:5150-8. [PMID: 3244350 PMCID: PMC365617 DOI: 10.1128/mcb.8.12.5150-5158.1988] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We have investigated mitochondrial import and processing of the precursor for human ornithine transcarbamylase (OTC; carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) in HeLa cells stably transformed with cDNA sequences encoding OTC precursors carrying mutations in their leader peptides. The mutant precursors studied included two with amino acid substitutions in the 32-amino-acid leader peptide (glycine for arginine at position 23, designated gly23; glycines for arginines at positions 15, 23, and 26, designated gly15,23,26) and two with deletions (deletion of residues 8 to 22, designated d8-22; deletion of residues 17 to 32, designated N16). Specific immunoprecipitation with anti-OTC antiserum of extracts of L-[35S]methionine-labeled cells expressing these mutations yielded only precursor species; neither mature nor intermediate-size OTC subunits were observed. Fractionation of radiolabeled cells, however, revealed important differences among the various mutants: the gly23 precursor was associated with mitochondria and was not detected in the cytosol; the d8-22 and N16 precursors were found with both the mitochondrial fraction and the cytosol; only the gly15,23,26 precursor was detected exclusively in the cytosol. A large fraction of each of the mitochondrially associated OTC species was in a trypsin-protected compartment. In particular, the gly23 precursor behaved in trypsin protection and mitochondrial fractionation studies in a manner consistent with its translocation into the mitochondrial matrix. On the other hand, the lack of binding of the gly23 protein to a delta-N-phosphonoacetyl-L-ornithine affinity column, which specifically recognizes active OTC enzyme, indicated that, despite its intramitochondrial location, the mutant protein did not assemble into the normal, active trimer. Further, the gly23 mutant precursor was unstable within the mitochondria and was degraded with a t1/2 of less further than 4 h. Thus, we have shown that, in intact HeLa cells, cleavage of the OTC leader peptide is not required for translocation into mitochondria, but is required for assembly into active enzyme.
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Affiliation(s)
- G Isaya
- Department of Human Genetics, Yale University School of Medicine, New Haven, Connecticut 06510
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Powers-Lee SG, Mastico RA, Bendayan M. The interaction of rat liver carbamoyl phosphate synthetase and ornithine transcarbamoylase with inner mitochondrial membranes. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47781-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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8
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Abstract
The relative half-life of ornithine transcarbamylase from rat liver has been determined using the double isotope technique and affinity chromatography. The calculated half-life (6-9 days) is similar to that of mitochondria and of the other mitochondrial enzyme of the urea cycle, carbamoyl-phosphate synthase. Therefore, both mitochondrial urea cycle enzymes are most probably degraded mainly via the lysosomal (autophagic) pathway of mitochondrial protein degradation.
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Yokota S, Mori M. Immunoelectron microscopical localization of ornithine transcarbamylase in hepatic parenchymal cells of the rat. THE HISTOCHEMICAL JOURNAL 1986; 18:451-7. [PMID: 3536806 DOI: 10.1007/bf01675338] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The electron microscopical localization of ornithine transcarbamylase in rat liver was investigated by a protein A-gold technique applied to thin sections of Lowicryl K4M- or LR gold-embedded materials and to ultracryosections. Gold particles were exclusively confined to mitochondria of the parenchymal cells but not of sinus-lining cells. In mitochondria, gold particles were present in the matrix and closely associated with the inner membrane. The most intensive labelling was obtained from ultracryosections, while weaker labelling was noted in sections of materials embedded in both Lowicryl K4M and LR gold. The association of the enzyme with the inner membrane was confirmed by quantitative analysis of distribution pattern.
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Miller NT, Feibush B, Corina K, Powers-Lee S, Karger BL. High-performance hydrophobic interaction chromatography: purification of rat liver carbamoylphosphate synthetase I and ornithine transcarbamoylase. Anal Biochem 1985; 148:510-7. [PMID: 4061826 DOI: 10.1016/0003-2697(85)90260-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The applicability of high-performance hydrophobic interaction chromatography using newly developed silica-based ether-bonded phases is demonstrated in the purification of the rat liver enzymes carbamoylphosphate synthetase I and ornithine transcarbamoylase from crude mitochondrial extracts. As a result of the mild adsorption/elution conditions in this high-performance chromatographic mode, the enzymes are recovered in 20 min with 3- to 15-fold increases in specific activity. Since the enzymes are labile and may aggregate in solution, in one case up to Mr 330,000, this rapid purification demonstrates the potential of hydrophobic interaction chromatography in complex biological systems.
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11
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Bates M, Weiss RL, Clarke S. Ornithine transcarbamylase from Neurospora crassa: purification and properties. Arch Biochem Biophys 1985; 239:172-83. [PMID: 3159341 DOI: 10.1016/0003-9861(85)90824-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Ornithine transcarbamylase catalyzes the synthesis of citrulline from carbamyl phosphate and ornithine. This enzyme is involved in the biosynthesis of arginine in many organisms and participates in the urea cycle of mammals. The biosynthetic ornithine transcarbamylase has been purified from the filamentous fungus, Neurospora crassa. It was found to be a homotrimer with an apparent subunit molecular weight of 37,000 and a native molecular weight of about 110,000. Its catalytic activity has a pH optimum of 9.5 and Km's of about 5 and 2.5 mM for the substrates, ornithine and carbamyl phosphate, respectively, at pH 9.5. The Km's and pH optimum are much higher than those of previously characterized enzymes from bacteria, other fungi, and mammals. These unusual kinetic properties may be of significance with regard to the regulation of ornithine transcarbamylase in this organism, especially in the avoidance of a futile ornithine cycle. Polyclonal antibodies were raised against the purified enzyme. These antibodies and antibody raised against purified rat liver ornithine transcarbamylase were used to examine the structural similarities of the enzyme from a number of organisms. Cross-reactivity was observed only for mitochondrial ornithine transcarbamylases of related organisms.
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12
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Kalousek F, Orsulak MD, Rosenberg LE. Newly processed ornithine transcarbamylase subunits are assembled to trimers in rat liver mitochondria. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)91020-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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13
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D'Souza SF, Srere PA. Cross-linking of mitochondrial matrix proteins in situ. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 724:40-51. [PMID: 6409145 DOI: 10.1016/0005-2728(83)90023-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Different cross-linkers (10 mM) of varying specificity and arm length were found to cross-link mitochondria matrix proteins in situ in 2 min at pH 7.4. As seen by SDS-polyacrylamide electrophoresis, the disappearance of individual protein bands was accompanied by concomitant appearance of polymeric aggregates that failed to enter the 4% spacer gel. The disorganization of the mitochondrial matrix infrastructure either by swelling or sonication of the mitochondria resulted in a decrease in the rate of cross-linking. Leakage of citrate synthase, malate dehydrogenase and fumarase was found to be reduced when cross-linked mitochondria were made permeable with toluene. On lysing the cross-linked mitochondria, a major part of the matrix protein (75%) was found to sediment with the membrane fraction. The activities of citrate synthase malate dehydrogenase and fumarase in rat liver mitochondria were also found to increase in the percipitates with concomitant decrease in their activities in the soluble matrix fraction. These results indicate that the cross-linkers enters the mitochondria and cross-links matrix proteins including Krebs cycle enzymes either to the mitochondrial membranes, or to themselves resulting in very large molecular weight complexes. These results are interpreted to mean that in liver mitochondria, the Krebs cycle enzyme are preferentially located near the membrane.
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14
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Miura S, Mori M, Tatibana M. Transport of ornithine carbamoyltransferase precursor into mitochondria. Stimulation by potassium ion, magnesium ion, and a reticulocyte cytosolic protein(s). J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32264-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kolansky DM, Conboy JG, Fenton WA, Rosenberg LE. Energy-dependent translocation of the precursor of ornithine transcarbamylase by isolated rat liver mitochondria. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34355-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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16
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Pre-ornithine transcarbamylase. Properties of the cytoplasmic precursor of a mitochondrial matrix enzyme. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68500-5] [Citation(s) in RCA: 35] [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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Briand P, Cathelineau L, Kamoun P, Gigot D, Penninckx M. Increase of ornithine transcarbamylase protein in sparse-fur mice with ornithine transcarbamylase deficiency. FEBS Lett 1981; 130:65-8. [PMID: 6793393 DOI: 10.1016/0014-5793(81)80666-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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18
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Conboy JG, Rosenberg LE. Posttranslational uptake and processing of in vitro synthesized ornithine transcarbamoylase precursor by isolated rat liver mitochondria. Proc Natl Acad Sci U S A 1981; 78:3073-7. [PMID: 6942417 PMCID: PMC319502 DOI: 10.1073/pnas.78.5.3073] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The mitochondrial matrix enzyme ornithine transcarbamoylase (OTCase; ornithine carbamoyltransferase; carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) is encoded by a nuclear gene on the X chromosome, synthesized on cytoplasmic ribosomes, and translocated across both mitochondrial membranes. Using specific immunoprecipitation, we presented evidence previously that the primary in vitro translation product of OTCase in rat liver is a polypeptide about 4000 daltons larger than the "mature" OTCase augment subunit purified from homologous mitochondria. In this report we augment the immunological identification of this cell-free translation product (pOTCase) with structural information and show, by electrophoresis of proteolysis products, that pOTCase is structurally similar to mitochondrial OTCase. Moreover, we now demonstrate that, when pOTCase is incubated posttranslationally with isolated rat liver mitochondria, it is converted to the size of mature OTCase and is sequestered within the mitochondria in such a way that it becomes resistant to externally added proteases. Such posttranslational processing is catalyzed specifically by the mitochondrial fraction of rat liver cells and is dependent both on the duration of incubation with mitochondria and on the amount of mitochondrial protein added. We conclude that pOTCase is indeed the bona fide precursor of mitochondrial OTCase and that use of this simplified cell-free system will facilitate analysis of OTCase biogenesis at both the cellular and the molecular level.
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Mori M, Miura S, Tatibana M, Cohen P. Cell-free translation of carbamyl phosphate synthetase I and ornithine transcarbamylase messenger RNAs of rat liver. Effect of dietary protein and fasting on translatable mRNA levels. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69575-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Morita T, Mori M, Tatibana M, Cohen PP. Site of synthesis and intracellular transport of the precursor of mitochondrial ornithine carbamoyltransferase. Biochem Biophys Res Commun 1981; 99:623-9. [PMID: 7236288 DOI: 10.1016/0006-291x(81)91790-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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21
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Cohen PP. The ornithine-urea cycle: biosynthesis and regulation of carbamyl phosphate synthetase I and ornithine transcarbamylase. CURRENT TOPICS IN CELLULAR REGULATION 1981; 18:1-19. [PMID: 7023854 DOI: 10.1016/b978-0-12-152818-8.50008-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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22
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Mori M, Miura S, Tatibana M, Cohen PP. Characterization of a protease apparently involved in processing of pre-ornithine transcarbamylase of rat liver. Proc Natl Acad Sci U S A 1980; 77:7044-8. [PMID: 7012832 PMCID: PMC350437 DOI: 10.1073/pnas.77.12.7044] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The precursor of rat liver ornithine transcarbamylase (ornithine carbamoyltransferase; carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) (pre-ornithine transcarbamylase), which was synthesized in a reticulocyte lysate cell-free system, was converted to an apparently mature form of the enzyme by isolated rat liver mitochondria. The proteolytic processing involved two steps: (i) conversion of pre-ornithine transcarbamylase (39,400 daltons) to a product of about 37,000 daltons and (ii) further conversion to the apparently mature form of the enzyme (36,00 daltons). When mitochondria were subfractionated by digitonin treatment followed by sonication of a mitoplast fraction, the proteolytic activity catalyzing the first step was recovered mainly in a matrix fraction. Some activity was found in an intermembrane space fraction. The enzyme activity in the matrix fraction has an optimal pH at about 7.5. The activity was inhibited almost completely by 2 mM leupeptin and partly by 2 mM antipain but not significantly by other microbial protease inhibitors or serine protease inhibitors. It was inhibited strongly by 2 mM EDTA, 2 mM ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetate, 2 mM p-chloromercuriphenylsulfonate, and 2 mM Hg(CH3COO)2 but not by N-ethylmaleimide or iodoacetamide. These results suggest that pre-ornithine transcarbamylase is first transported into the mitochondrial matrix and converted there to the mature form of the enzyme by a novel neutral protease(s).
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Mori M, Uchiyama C, Miura S, Tatibana M, Nagayama E. Ornithine carbamoyltransferase deficiency: coexistence of active and inactive forms of enzyme. Clin Chim Acta 1980; 104:291-9. [PMID: 7389139 DOI: 10.1016/0009-8981(80)90386-1] [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: 01/25/2023]
Abstract
Kinetic and molecular properties of liver ornithine carbamoyltransferase from a female patient with the enzyme deficiency were studied. The enzyme activity in the patient was 9% of that in controls. Kinetic properties of the enzyme from the patient appeared to be identical to those of the control enzyme; apparent Km values for L-ornithine and carbamoyl-phosphate at pH 7.2 were 1.3 mmol/l and 7.9 mumol/l, respectively. Patient and control livers contained similar amounts of protein cross-reactive with antibody to the bovine enzyme. No difference in the subunit size was observed between the patient enzyme and the control enzyme. When extracts of control liver were analyzed by isoelectric focusing, a major peak of immunoreactive protein with a pI value of 7.3 and a minor peak with a pI value of 6.8 were observed, and both forms were enzymatically active. On the other hand, extracts of the patient's liver gave a major peak of immunoreactive protein with a pI value of 7.0 and a minor one with a pI of 6.8; the minor form was enzymatically active while the major one showed little or no activity. These results indicate that the patient's liver contained an inactive form of ornithine carbamoyltransferase in addition to an active form of the enzyme, and may reflect the X-linkage of the enzyme at the molecular level.
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Hoogenraad NJ, Sutherland TM, Howlett GJ. Purification of ornithine transcarbamylase from rat liver by affinity chromatography with immobilized transition-state analog. Anal Biochem 1980; 101:97-102. [PMID: 7356142 DOI: 10.1016/0003-2697(80)90045-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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26
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Henslee JG, Srere PA. Resolution of rat mitochondrial matrix proteins by two-dimensional polyacrylamide gel electrophoresis. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50622-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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27
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Kalousek F, François B, Rosenberg L. Isolation and characterization of ornithine transcarbamylase from normal human liver. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34781-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Hoogenraad NJ. Synthesis and properties of delta-N-(phosphonacetyl)-L-ornithine. A transition-state analog inhibitor of ornithine transcarbamylase. Arch Biochem Biophys 1978; 188:137-44. [PMID: 677887 DOI: 10.1016/0003-9861(78)90366-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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29
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Pierson DL, Cox SL, Gilbert BE. Human ornithine transcarbamylase. Purification and characterization of the enzyme from normal liver and the liver of a Reye's syndrome patient. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(17)39981-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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