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Abstract
This article--a mini-memoir--focuses on the first half of my half-century-long career as a human geneticist: its accidental beginnings; its early bad and then good fortunes at the National Institutes of Health; its serendipitous successes and career-making scientific productivity at Yale; and its incalculable fortuity in the form of the large number of talented and resourceful mentors, colleagues, postdoctoral fellows, graduate students, and technicians who worked with me. These years acted as a launchpad for positions of visibility and leadership that followed them. My personal odyssey, which began in Madison, Wisconsin, and meandered with no fixed plan to New York, Bethesda, New Haven, and Princeton, has offered me life views as a human and medical geneticist that are panoramic, splendid, and indelible. I doubt that many people have been as fortunate as I have been in the professional life I have lived--and continue to live.
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Affiliation(s)
- Leon E Rosenberg
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544;
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2
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Takahashi-Iñiguez T, García-Hernandez E, Arreguín-Espinosa R, Flores ME. Role of vitamin B12 on methylmalonyl-CoA mutase activity. J Zhejiang Univ Sci B 2012; 13:423-37. [PMID: 22661206 DOI: 10.1631/jzus.b1100329] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Vitamin B(12) is an organometallic compound with important metabolic derivatives that act as cofactors of certain enzymes, which have been grouped into three subfamilies depending on their cofactors. Among them, methylmalonyl-CoA mutase (MCM) has been extensively studied. This enzyme catalyzes the reversible isomerization of L-methylmalonyl-CoA to succinyl-CoA using adenosylcobalamin (AdoCbl) as a cofactor participating in the generation of radicals that allow isomerization of the substrate. The crystal structure of MCM determined in Propionibacterium freudenreichii var. shermanii has helped to elucidate the role of this cofactor AdoCbl in the reaction to specify the mechanism by which radicals are generated from the coenzyme and to clarify the interactions between the enzyme, coenzyme, and substrate. The existence of human methylmalonic acidemia (MMA) due to the presence of mutations in MCM shows the importance of its role in metabolism. The recent crystallization of the human MCM has shown that despite being similar to the bacterial protein, there are significant differences in the structural organization of the two proteins. Recent studies have identified the involvement of an accessory protein called MMAA, which interacts with MCM to prevent MCM's inactivation or acts as a chaperone to promote regeneration of inactivated enzyme. The interdisciplinary studies using this protein as a model in different organisms have helped to elucidate the mechanism of action of this isomerase, the impact of mutations at a functional level and their repercussion in the development and progression of MMA in humans. It is still necessary to study the mechanisms involved in more detail using new methods.
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Affiliation(s)
- Tóshiko Takahashi-Iñiguez
- Department of Molecular Biology and Biotechnology, Institute of Biomedical Research, National Autonomous University of Mexico, D.F. 04510, Mexico.
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Evidence for catabolic pathway of propionate metabolism in CNS: expression pattern of methylmalonyl-CoA mutase and propionyl-CoA carboxylase alpha-subunit in developing and adult rat brain. Neuroscience 2009; 164:578-87. [PMID: 19699272 DOI: 10.1016/j.neuroscience.2009.08.028] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 08/11/2009] [Accepted: 08/12/2009] [Indexed: 11/23/2022]
Abstract
Methylmalonyl-CoA mutase (MCM) and propionyl-CoA carboxylase (PCC) are the key enzymes of the catabolic pathway of propionate metabolism and are mainly expressed in liver, kidney and heart. Deficiency of these enzymes leads to two classical organic acidurias: methylmalonic and propionic aciduria. Patients with these diseases suffer from a whole spectrum of neurological manifestations that are limiting their quality of life. Current treatment does not seem to effectively prevent neurological deterioration and pathophysiological mechanisms are poorly understood. In this article we show evidence for the expression of the catabolic pathway of propionate metabolism in the developing and adult rat CNS. Both, MCM and PCC enzymes are co-expressed in neurons and found in all regions of the CNS. Disease-specific metabolites such as methylmalonate, propionyl-CoA and 2-methylcitrate could thus be formed autonomously in the CNS and contribute to the pathophysiological mechanisms of neurotoxicity. In rat embryos (E15.5 and E18.5), MCM and PCC show a much higher expression level in the entire CNS than in the liver, suggesting a different, but important function of this pathway during brain development.
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4
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3-Hydroxy-3-methylglutaryl coenzyme A lyase: targeting and processing in peroxisomes and mitochondria. J Lipid Res 1999. [DOI: 10.1016/s0022-2275(20)33340-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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5
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Linnell JC, Bhatt HR. Inherited errors of cobalamin metabolism and their management. BAILLIERE'S CLINICAL HAEMATOLOGY 1995; 8:567-601. [PMID: 8534962 DOI: 10.1016/s0950-3536(05)80221-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cobalamins are essential biological compounds structurally related to haemoglobin and the cytochromes. Although the basic cobalamin molecule is only synthesized by micro-organisms, all mammalian cells can convert this into the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). AdoCbl is the major form in cellular tissues, where it is retained in the mitochondria. MeCbl predominates in blood plasma and certain other body fluids such as breast milk; in cells MeCbl is found in the cytosol. Inherited disorders of cobalamin metabolism are single gene defects, transmitted as recessive traits. They affect absorption, transport or intracellular metabolism of cobalamin. At least 12 different mutations are known, including defects or deficiencies of IF, IF-receptor and TCII, MM-CoA mutase and of the various reductases and synthases required for synthesis of AdoCbl and MeCbl. These have been designated cblA to cblG. Abnormalities are detectable by urine and plasma assays of methylmalonic acid and homocysteine, and plasma and erythrocyte analysis of cobalamin coenzymes, which can reveal deficiencies of MeCbl or AdoCbl. Fibroblast studies discriminate between closely similar defects. In man, AdoCbl is required in only two reactions: the catabolic isomerization of MM-CoA to succinyl-CoA and interconversion of alpha- and beta-leucine. MeCbl is required in the anabolic transmethylation of homocysteine to methionine. Intestinal absorption of cobalamin requires the glycoproteins TCI and IF from the stomach and IF-cobalamin receptors in the ileum. Cobalamin is transported to cells bound to a polypeptide, TCII, is captured by surface receptors and absorbed by endocytosis. The complex is then split in the lysosomes, cobalamin is released and the coenzymes are synthesized. In plasma, 80-90% of the cobalamin is bound to TCI, whose function is uncertain. Megaloblastic anaemia at birth or in the first few weeks of life is a rare but serious event. Myelopathy and developmental delay, with or without seizures may also occur without anaemia. If urine and light-protected blood samples are collected and sent to an appropriate metabolic unit, an inborn error of cobalamin metabolism, including TCII deficiency in which the serum B12 may be normal, can quickly be diagnosed. IF deficiency or Imerslund-Gräsbeck disease usually presents with signs of cobalamin deficiency within the first year of life and can be diagnosed by absorption studies. Current treatment involves dietary protein restriction and/or parenteral OHCbl and the prognosis is very variable. Since lack of MeCbl leads to depressed DNA synthesis affecting rapidly dividing cells in the brain and elsewhere, treatment with this coenzyme should be considered at the earliest stage in appropriate cases.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J C Linnell
- Vitamin B12 Unit, Chelsea and Westminster Hospital, London, UK
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6
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Sloan IS, Horowitz PM, Chirgwin JM. Rapid secretion by a nonclassical pathway of overexpressed mammalian mitochondrial rhodanese. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47030-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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7
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8
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Qureshi AA, Rosenblatt DS, Cooper BA. Inherited disorders of cobalamin metabolism. Crit Rev Oncol Hematol 1994; 17:133-51. [PMID: 7818787 DOI: 10.1016/1040-8428(94)90022-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- A A Qureshi
- Department of Human Genetics, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada
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9
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Mitochondrial import and processing of rat liver carnitine palmitoyltransferase II defines the amino terminus of the mature protein. Possibility of differential modification of the rat and human isoforms. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98636-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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10
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Taroni F, Rosenberg L. The precursor of the biotin-binding subunit of mammalian propionyl-CoA carboxylase can be translocated into mitochondria as apo- or holoprotein. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98833-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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11
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Ohura T, Miyabayashi S, Narisawa K, Tada K. Genetic heterogeneity of propionic acidemia: analysis of 15 Japanese patients. Hum Genet 1991; 87:41-4. [PMID: 2037281 DOI: 10.1007/bf01213089] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Propionic acidemia is an autosomal recessive metabolic disease resulting from a deficiency of propionyl CoA carboxylase (PCC) activity. We have analyzed the molecular heterogeneity of Japanese propionic acidemia patients using anti-human PCC antiserum and cDNA clones coding for the two protein subunits (alpha and beta) of the enzyme. The steady state levels of both alpha and beta subunits of PCC from 15 Japanese patients were determined by Western blot. Three patients had neither alpha nor beta subunits, and the amounts of both alpha and beta subunits were low in 3 other patients. According to our previous data, we classified these 6 patients as having alpha subunit deficiency. In the remaining 8 patients, alpha subunits were normal, but the beta subunits were aberrant. Two patients had low levels of normal-sized beta subunits and 6 had beta subunits smaller than normal in size and greatly reduced in quantity. These 8 patients were assigned to the beta subunit deficiency category. One patient had apparently normal alpha and beta subunits. We could not determine this patient's primary defect. These data reveal the genetic heterogeneity of molecular defects causing propionic acidemia in the Japanese. Southern blot analysis did not reveal any gross alteration in gene structure when DNA was digested with HindIII, EcoRI and TaqI. However, DNA from 3 beta-subunit-deficient patients, when digested with MspI and probed with beta PCC cDNA, revealed a unique 2.7-kb band not observed in blots of DNA from any other patient or 15 normal controls. We conclude that this altered MspI restriction map is the result of a mutation in the beta subunit gene of these patients.
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Affiliation(s)
- T Ohura
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
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12
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Abstract
The MUT locus encoding the enzyme methylmalonyl-CoA mutase is defective in mut forms of methylmalonic acidemia. This locus has been mapped to chromosome 6p12-21.1. We report cloning and characterization of this locus which comprises 13 exons spanning greater than 35 kb of the genome. The MUT locus exhibits consensus sequences for transcription, splicing, and polyadenylation. The putative promoter region was localized in a CG island 5' to exon I and was shown to direct expression of a beta-galactosidase reporter gene in cultured cells. Of interest is the observation that the first intron occurs within the 5' untranslated region, and no introns separate the mitochondrial targeting sequences and the mature apoenzyme. An informative HindIII polymorphism was localized within the coding sequence and can be assayed using the polymerase chain reaction. These studies describe the structure of the MUTlocus and provide a foundation for characterization of mutations in mut methylmalonic acidemia.
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Affiliation(s)
- S U Nham
- Howard Hughes Medical Institute, Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030
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13
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Ledley FD. Perspectives on methylmalonic acidemia resulting from molecular cloning of methylmalonyl CoA mutase. Bioessays 1990; 12:335-40. [PMID: 1975493 DOI: 10.1002/bies.950120706] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Methylmalonyl CoA mutase deficiency (methylmalonic acidemia) has been a paradigm for biochemical and somatic cell genetic approaches to human disease. Recently, genes encoding this enzyme have been cloned from several species. These studies have provided information about the primary structure and evolution of this enzyme, the mutations which underlie its deficiency state, and the structure-function determinants which are required for its activity. Gene transfer studies now permit restitution of this enzyme to genetically deficient cells and may enable somatic gene therapy to be undertaken. Molecular genetic studies not only provide more detailed information about this enzyme, but introduce new perspectives on the molecular mechanisms and dynamics of its function and raise new questions about the dyshomeostatic consequences of its deficiency.
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Affiliation(s)
- F D Ledley
- Howard Hughes Medical Institute, Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030
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14
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Cooper BA, Rosenblatt DS, Watkins D. Methylmalonic aciduria due to a new defect in adenosylcobalamin accumulation by cells. Am J Hematol 1990; 34:115-20. [PMID: 2339678 DOI: 10.1002/ajh.2830340207] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A child with methylmalonic aciduria due to failure to accumulate adocbl in mitochondria has a phenotype similar to cblA disease. Deficient utilization of labeled propionate by his fibroblasts is corrected by their fusion with those from cblA patients, indicating that he belongs to a different complementation class and probably is deficient in a different gene product. The defect appears not to be due to reduced affinity of enzymes for adocbl, or for ATP, and the minimal thiol required for adocbl synthesis is not different from that of extracts of normal cells.
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Affiliation(s)
- B A Cooper
- Division of Hematology-Oncology, Royal Victoria Hospital, Montreal, Canada
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15
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Jansen R, Kalousek F, Fenton WA, Rosenberg LE, Ledley FD. Cloning of full-length methylmalonyl-CoA mutase from a cDNA library using the polymerase chain reaction. Genomics 1989; 4:198-205. [PMID: 2567699 DOI: 10.1016/0888-7543(89)90300-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The polymerase chain reaction was used to clone a full-length human methylmalonyl-CoA mutase cDNA from a human liver library by priming with sequences from the 5' end of a partial cDNA and sequences in the phage vector. The amino acid sequence predicted from the cDNA corresponds to the authentic amino acid sequences of peptide fragment from purified methylmalonyl-CoA mutase. The open reading frame of the cDNA encodes 742 amino acids (82,283 Da) comprising a 32 amino acid mitochondrial leader sequence and a mature protein of 710 amino acids (78,489 Da). The use of the polymerase chain reaction to "screen" the cDNA library represents a novel application of this technique. The full length will enable analysis of mutations underlying inherited methylmalonic acidemias caused by deficiency of the methylmalonyl-CoA mutase apoenzyme.
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Affiliation(s)
- R Jansen
- Howard Hughes Medical Institute, Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030
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16
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17
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Molecular cloning and nucleotide sequence of cDNAs encoding the alpha-subunit of human electron transfer flavoprotein. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)37655-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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18
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Flückiger J, Christen P. Degradation of the precursor of mitochondrial aspartate aminotransferase in chicken embryo fibroblasts. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68899-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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Ikeda Y, Tanaka K. Mutant isovaleryl-CoA dehydrogenase in isovaleric acidemia cells: assay of activity and molecular characterization. Methods Enzymol 1988; 166:155-66. [PMID: 3071699 DOI: 10.1016/s0076-6879(88)66022-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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20
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Mahoney MJ, Bick D. Recent advances in the inherited methylmalonic acidemias. ACTA PAEDIATRICA SCANDINAVICA 1987; 76:689-96. [PMID: 2889315 DOI: 10.1111/j.1651-2227.1987.tb10551.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Methylmalonic acidemia results from decreased activity of methylalonyl-CoA mutase, an enzyme required for the catabolism of four amino acids. A cobalamin (vitamin B12) compound is required as coenzyme. Several inherited mutations of the mutase apoenzyme or of cobalamin coenzyme synthesis have been identified. Clinical disease is most commonly recognized as a severe protein intolerance state although a wide range of symptoms has been appreciated. Current therapy emphasizes strict dietary management and use of vitamin B12 in cobalamin responsive patients.
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Affiliation(s)
- M J Mahoney
- Department of Human Genetics, Yale University School of Medicine, New Haven, Connecticut
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21
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Lubin IM, Wu LN, Wuthier RE, Fisher RR. Rhodamine 123 inhibits import of rat liver mitochondrial transhydrogenase. Biochem Biophys Res Commun 1987; 144:477-83. [PMID: 3579920 DOI: 10.1016/s0006-291x(87)80534-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Rhodamine 123, a laser dye, has been demonstrated to inhibit import of the precursor to pyridine dinucleotide transhydrogenase into mitochondria in rat liver cells. When rat hepatocytes were labeled with 35[S] methionine in the presence of 0.4 mM rhodamine 123, the precursor to transhydrogenase was found to have a half-life in the cytoplasm of 15 minutes as opposed to a half-life of 1-2 minutes when cells were radiolabeled in the absence of the dye. To clarify the mechanism of import inhibition, studies were initiated to assess the effect of rhodamine 123 on mitochondrial respiration. Upon addition of the dye to a mitochondrial suspension, respiration was initially enhanced, then inhibited. The inability of FCCP, a classical uncoupler, to enhance respiration during the inhibitory phase suggests that rhodamine 123 is primarily inhibiting respiration through the electron transport system rather than through the ATPase. These results suggest that rhodamine 123 may inhibit import of the transhydrogenase precursor into mitochondria by disrupting components in the mitochondrial membrane necessary for efficient import.
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22
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Ikeda Y, Keese SM, Fenton WA, Tanaka K. Biosynthesis of four rat liver mitochondrial acyl-CoA dehydrogenases: in vitro synthesis, import into mitochondria, and processing of their precursors in a cell-free system and in cultured cells. Arch Biochem Biophys 1987; 252:662-74. [PMID: 3813556 DOI: 10.1016/0003-9861(87)90072-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The synthesis, translocation, processing, and assembly of rat liver short chain acyl-CoA, medium chain acyl-CoA, long chain acyl-CoA, and isovaleryl-CoA dehydrogenases were studied. These four acyl-CoA dehydrogenases are homotetrameric flavoproteins which are located in the mitochondrial matrix. They were synthesized in a cell-free rabbit reticulocyte lysate system, programmed by rat liver polysomal RNA, as precursor polypeptides which are 2-4 kDa larger than their corresponding mature subunits (Mr 41,000-45,000). When the radiolabeled precursors were incubated with intact rat liver mitochondria, they appeared to bind tightly to the mitochondrial outer membrane. At this stage they were completely susceptible to the action of exogenous trypsin. The precursors bound to mitochondria at 0 degrees C were translocated into the mitochondria and processed when the temperature was raised to 30 degrees C. No reaction occurred when the temperature was kept at 0 degrees C, however, suggesting that the binding of the precursors is temperature independent while the subsequent steps of the pathway are energy dependent. Indeed, the translocation reaction was inhibited by compounds such as dinitrophenol and rhodamine 6G which inhibit mitochondrial energy metabolism. The newly imported (mature) enzymes were inaccessible to the proteolytic action of added trypsin. The processing of the precursors to mature subunits was proteolytically carried out in the mitochondrial matrix, and the processed mature subunits mostly assembled to their respective tetrameric forms. Newly synthesized larger precursors of each of the four acyl-CoA dehydrogenases were recovered from intact, cultured Buffalo rat liver cells in the presence of dinitrophenol. When dinitrophenol was removed in a pulse-chase protocol, the accumulated precursors were rapidly (t1/2 3-5 min) converted to their corresponding mature subunits. On the other hand, when the chase was performed in the presence of the inhibitor, the labeled precursors disappeared with t1/2 of greater than 4 h for long chain acyl-CoA dehydrogenase and 1-2 h for the other three enzyme precursors.
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23
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Biogenesis of Mammalian Mitochondria. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/b978-0-12-152515-6.50012-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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24
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Rosenberg LE, Fenton WA, Horwich AL, Kalousek F, Kraus JP. Targeting of nuclear-encoded proteins to the mitochondrial matrix: implications for human genetic defects. Ann N Y Acad Sci 1986; 488:99-108. [PMID: 3472484 DOI: 10.1111/j.1749-6632.1986.tb46550.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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25
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Behra R, Christen P. In vitro import into mitochondria of the precursor of mitochondrial aspartate aminotransferase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)42463-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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26
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Gietl C, Hock B. Import of glyoxysomal malate dehydrogenase precursor into glyoxysomes: A heterologous in-vitro system. PLANTA 1986; 167:87-93. [PMID: 24241736 DOI: 10.1007/bf00446373] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/1985] [Accepted: 09/09/1985] [Indexed: 06/02/2023]
Abstract
A heterologous in-vitro system is described for the import of the precursor to glyoxysomal malate dehydrogenase from watermelon (Citrullus vulgaris Schrad., cv. Kleckey's Sweet No. 6) cotyledons into glyoxysomes from castor-bean (Ricinus communis L.) endosperm. The 41-kDa precursor is posttranslationally sequestered and correctly processed to the mature 33-kDa subunit by a crude glyoxysomal fraction or by glyoxysomes purified on a sucrose gradient. The import and the cleavage of the extrasequence is not inhibited by metal chelators such as 1,10-phenanthroline and ethylenediaminetetraacetic acid. Uncouplers (carbonylcyanide m-chlorophenylhydrazone), ionophores (valinomycin), or inhibitors of oxidative phosphorylation (oligomycin) and ATP-ADP translocation (carboxyatractyloside) do not interfere, thus indicating the independence of the process of import by the organelle from the energization of the glyoxysomal membrane.
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Affiliation(s)
- C Gietl
- Department of Botany, Faculty of Agriculture and Horticulture, Technical University of Munich, D-8050, Freising 12, Germany
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27
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Matocha MF, Waterman MR. Synthesis and processing of mitochondrial steroid hydroxylases. In vivo maturation of the precursor forms of cytochrome P-450scc, cytochrome P-450(11)beta, and adrenodoxin. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39019-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [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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Wu LN, Lubin IM, Fisher RR. Biosynthesis of rat liver transhydrogenase in vivo and in vitro. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)88980-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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29
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Firgaira FA, Hendrick JP, Kalousek F, Kraus JP, Rosenberg LE. RNA required for import of precursor proteins into mitochondria. Science 1984; 226:1319-22. [PMID: 6209799 DOI: 10.1126/science.6209799] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A cytoplasmic RNA moiety is necessary for posttranslational uptake of nuclear-encoded mammalian proteins destined for the mitochondrial matrix. Post-translational addition of ribonuclease to a reticulocyte lysate-programmed cell-free translation mixture inhibited subsequent import of six different mitochondrial matrix enzyme precursors into rat liver mitochondria. The required RNA is highly protected, as indicated by the high concentrations of ribonuclease necessary to produce this inhibition. The dependence of the inhibitory effect on temperature, duration of exposure to ribonuclease, and availability of divalent cations is characteristic of the nuclease susceptibility of ribonucleoproteins. The ribonuclease-sensitive component was found in a 400-kilodalton fraction which contains the mitochondrial protein precursors.
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