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Strangers in strange lands: mitochondrial proteins found at extra-mitochondrial locations. Biochem J 2019; 476:25-37. [DOI: 10.1042/bcj20180473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 11/23/2018] [Accepted: 11/27/2018] [Indexed: 12/18/2022]
Abstract
Abstract
The mitochondrial proteome is estimated to contain ∼1100 proteins, the vast majority of which are nuclear-encoded, with only 13 proteins encoded by the mitochondrial genome. The import of these nuclear-encoded proteins into mitochondria was widely believed to be unidirectional, but recent discoveries have revealed that many these ‘mitochondrial’ proteins are exported, and have extra-mitochondrial activities divergent from their mitochondrial function. Surprisingly, three of the exported proteins discovered thus far are mitochondrially encoded and have significantly different extra-mitochondrial roles than those performed within the mitochondrion. In this review, we will detail the wide variety of proteins once thought to only reside within mitochondria, but now known to ‘emigrate’ from mitochondria in order to attain ‘dual citizenship’, present both within mitochondria and elsewhere.
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2
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Green BN, Suzuki T, Gotoh T, Kuchumov AR, Vinogradov SN. Electrospray ionization mass spectrometric determination of the complete polypeptide chain composition of Tylorrhynchus heterochaetus hemoglobin. J Biol Chem 1995; 270:18209-11. [PMID: 7629137 DOI: 10.1074/jbc.270.31.18209] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Electrospray ionization mass spectrometry (ESI-MS) of the native, reduced, and carbamidomethylated forms of the extracellular, 3.38-MDa hemoglobin from the marine polychaete Tylorrhynchus heterochaetus, when combined with a maximum entropy (MaxEnt) analysis, provided a complete description of the polypeptide chain composition. This hemoglobin, a hetero-multimeric complex of approximately 180 polypeptide chains, consisting of globin and linker subunits in an approximately 3:1 mass ratio, is among the largest protein complexes investigated by ESI-MS. The globin subunits consist of a monomer subunit (chain I, 15575.4 Da) and a disulfide-bonded trimer subunit, 50068.4 Da, consisting of globin chains IIA (16601.9 Da), IIB (16680.4 Da), and IIC (16,794.0 Da). Linker subunits L1-L5, 23233.8, 24835.4, 25326.9, 28202.2, and 26317.2 Da, respectively, were found together with a disulfide-bonded dimer of L2, 52609.4 Da. Using the exact masses of the subunits, a plausible model of the hemoglobin consisting of 144 globin chains (36 monomers and 36 trimers) and 36 linker chains provides a calculated mass of 3.42 MDa.
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Affiliation(s)
- B N Green
- VG Organic, Altrincham, Cheshire, United Kingdom
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3
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Jaussi R. Homologous nuclear-encoded mitochondrial and cytosolic isoproteins. A review of structure, biosynthesis and genes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 228:551-61. [PMID: 7737148 DOI: 10.1111/j.1432-1033.1995.tb20294.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Mitochondrial and cytosolic proteins may be expected to differ in specific traits due to their different intracellular location. However, the identification of these differences between mitochondrial and cytosolic proteins is complicated by the heterogeneity of the two protein groups. These difficulties have been overcome by comparing traits of homologous genes, which are derived from a common ancestor gene, and their gene products. An earlier report [Hartmann, C., Christen, P. & Jaussi, R. (1991) Nature 352, 762-763] describing a positive net charge difference between the mature parts of nuclear-encoded mitochondrial proteins and their homologous cytosolic isoproteins, could be corroborated by extending the data collection. New data were gathered from computer databases and published studies. The average isoelectric points of the mitochondrial and cytosolic isoproteins are 7.5 and 6.5, respectively. Depending on the type of protein, the observed difference results from differences in the number of basic and/or acidic amino acid residues in the isoproteins. Probably both the conditions required for mitochondrial protein import and the local conditions within the organelle furthered the evolution of basic protein structures. The contribution of the mitochondrial targeting peptide to the positive charge of precursors of nuclear-encoded mitochondrial proteins is largest when the value of the isoelectric point of the mature protein is small. This mutual dependence of the charge of the targeting peptide and the mature protein part supports the notion that positive charge is essential for mitochondrial protein import. Several traits other than electric charge, i.e. codon usage, chromosome location, structural organization or regulation of the genes, do not show specific differences between the sets of the heterotopic isoproteins. There is no preference of gene location for any of the gene sets; only rarely are the genes for a mitochondrial and a cytosolic isoprotein located on the same chromosome. A variant of the 3' splice-site consensus exists in genes of nuclear-encoded mitochondrial proteins. This is most likely a consequence of the evolution of the genes in separate lineages before endosymbiosis led to the formation of mitochondria. Some of the original mRNA group II intron self-splicing functions of the endosymbiont seem to persist in part of the cytosolic splicing machinery and apparently require a specific consensus sequence [Juretic, N., Jaussi, R., Mattes, U. & Christen, P. (1987) Nucleic Acids Res.15, 10083-10086].
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Affiliation(s)
- R Jaussi
- Institute of Medical Radiobiology, University of Zürich, Switzerland
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Hartmann CM, Gehring H, Christen P. The mature form of imported mitochondrial proteins undergoes conformational changes upon binding to isolated mitochondria. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 218:905-10. [PMID: 8281942 DOI: 10.1111/j.1432-1033.1993.tb18446.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mature mitochondrial proteins (aspartate aminotransferase, malate dehydrogenase, hydroxyacyl coenzyme A dehydrogenase, creatine kinase) and cytosolic proteins (aldolase, glyceraldehyde-3-phosphate dehydrogenase) with a basic pI were found to bind to isolated mitochondria, electrostatic interactions being mainly responsible for their binding. Mitochondrial aspartate aminotransferase bound with a Kd' of 30 nM in 0.6 M sorbitol, 20 mM Hepes/KOH, pH 7.4, at 25 degrees C. Cytosolic aspartate aminotransferase and glutamate dehydrogenase (a protein located in the mitochondrial matrix) both with an acidic pI, did not bind to mitochondria. Treatment of mitochondria with proteinases did not affect the subsequent binding of imported mitochondrial proteins. Their association with both intact and proteinase-treated mitochondria resulted in a marked increase in their susceptibility toward proteinase K. In contrast, the basic cytosolic proteins tested bound only to intact mitochondria and thereby did not become more susceptible toward proteolytic attack. Treatment of mitochondria with adriamycin, a drug binding to acidic phospholipids, prevented the subsequent association of mitochondrial aspartate aminotransferase with mitochondria and the ensuing conformational labilization. Apparently, the mature moiety of imported mitochondrial proteins is partially unfolded upon interaction with the lipid component of the mitochondrial envelope. Both the binding of the mitochondrial proteins and their conformational labilization is independent of ATP and the electrochemical potential across the inner membrane.
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Affiliation(s)
- C M Hartmann
- Biochemisches Institut der Universität Zürich, Switzerland
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Giannattasio S, Marra E, Abruzzese MF, Greco M, Quagliariello E. The in vitro-synthesized precursor and mature mitochondrial aspartate aminotransferase share the same import pathway in isolated mitochondria. Arch Biochem Biophys 1991; 290:528-34. [PMID: 1929419 DOI: 10.1016/0003-9861(91)90577-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Both the precursor and the mature form of mitochondrial aspartate aminotransferase were synthesized in a cell-free coupled transcription/translation system directed by the recombinant expression plasmid pOTS-pmAspAT and pOTS-mAspAT, respectively. Both newly synthesized forms of the protein were imported into isolated mitochondria, with the precursor correctly processed to the mature form. In both cases the import process showed resistance to externally added pronase and was abolished in mitochondria treated with the uncoupler carbonyl cyanide m-chlorophenylhydrazone. Moreover the imported products showed the same intramitochondrial localization as judged by a subfractionation procedure. In both cases import was time dependent and was completed in about 15 min. Finally a competitive inhibition of the import of the precursor of aspartate aminotransferase was found due to externally added purified aspartate aminotransferase.
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Affiliation(s)
- S Giannattasio
- C.N.R. Centro di Studio sui Mitocondri e Metabolismo Energetico, Bari, Italy
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6
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Hartmann CM, Lindenmann JM, Christen P, Jaussi R. The precursor of mitochondrial aspartate aminotransferase is imported into mitochondria faster than the homologous cytosolic isoenzyme with the same presequence attached. Biochem Biophys Res Commun 1991; 174:1232-8. [PMID: 1996986 DOI: 10.1016/0006-291x(91)91553-o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mitochondrial and cytosolic aspartate aminotransferase (AspAT) are homologous proteins with identically folded polypeptide chains. The cDNAs of the two isoenzymes of chicken were used to express the following proteins in yeast: the precursor of mitochondrial AspAT, mature mitochondrial AspAT, and two chimeric proteins in one of which (pc) the presequence of the precursor was attached to the entire cytosolic isoenzyme and in the other one (pmc) the N-terminal segment (amino acid residues -22 to 23) of the precursor was linked to the slightly truncated cytosolic isoenzyme (residues 34 to 412). All presequence containing proteins were imported into the mitochondria and processed to the mature form whereas mature mitochondrial AspAT remained in the cytosol. The rate of import of the authentic precursor was four times faster than that of the chimeric proteins pc and pmc, t1/2 for importation at 29 degrees C being 3, 13 and 14 min, respectively. Apparently, the mature moiety of the precursor of mitochondrial AspAT promotes importation.
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Affiliation(s)
- C M Hartmann
- Biochemisches Institut Universität Zürich, Switzerland
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7
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Perera SY, Chen TC, Curthoys NP. Biosynthesis and processing of renal mitochondrial glutaminase in cultured proximal tubular epithelial cells and in isolated mitochondria. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)38229-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Martinez-Carrion M, Altieri F, Iriarte AJ, Mattingly J, Youssef J, Wu TH. Precursor forms of mitochondrial aspartate transaminase. Ann N Y Acad Sci 1990; 585:346-56. [PMID: 2192618 DOI: 10.1111/j.1749-6632.1990.tb28067.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M Martinez-Carrion
- Division of Molecular Biology and Biochemistry, School of Basic Life Sciences, University of Missouri-Kansas City 64110
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Nishi T, Nagashima F, Tanase S, Fukumoto Y, Joh T, Shimada K, Matsukado Y, Ushio Y, Morino Y. Import and Processing of Precursor to Mitochondrial Aspartate Aminotransferase. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83310-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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10
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Altieri F, Mattingly JR, Rodriguez-Berrocal FJ, Youssef J, Iriarte A, Wu TH, Martinez-Carrion M. Isolation and Properties of a Liver Mitochondrial Precursor Protein to Aspartate Aminotransferase Expressed in Escherichia coli. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83658-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Hartl FU, Pfanner N, Nicholson DW, Neupert W. Mitochondrial protein import. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 988:1-45. [PMID: 2642391 DOI: 10.1016/0304-4157(89)90002-6] [Citation(s) in RCA: 531] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Most mitochondrial proteins are synthesized as precursor proteins on cytosolic polysomes and are subsequently imported into mitochondria. Many precursors carry amino-terminal presequences which contain information for their targeting to mitochondria. In several cases, targeting and sorting information is also contained in non-amino-terminal portions of the precursor protein. Nucleoside triphosphates are required to keep precursors in an import-competent (unfolded) conformation. The precursors bind to specific receptor proteins on the mitochondrial surface and interact with a general insertion protein (GIP) in the outer membrane. The initial interaction of the precursor with the inner membrane requires the mitochondrial membrane potential (delta psi) and occurs at contact sites between outer and inner membranes. Completion of translocation into the inner membrane or matrix is independent of delta psi. The presequences are cleaved off by the processing peptidase in the mitochondrial matrix. In several cases, a second proteolytic processing event is performed in either the matrix or in the intermembrane space. Other modifications can occur such as the addition of prosthetic groups (e.g., heme or Fe/S clusters). Some precursors of proteins of the intermembrane space or the outer surface of the inner membrane are retranslocated from the matrix space across the inner membrane to their functional destination ('conservative sorting'). Finally, many proteins are assembled in multi-subunit complexes. Exceptions to this general import pathway are known. Precursors of outer membrane proteins are transported directly into the outer membrane in a receptor-dependent manner. The precursor of cytochrome c is directly translocated across the outer membrane and thereby reaches the intermembrane space. In addition to the general sequence of events which occurs during mitochondrial protein import, current research focuses on the molecules themselves that are involved in these processes.
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Affiliation(s)
- F U Hartl
- Institut für Physiologische Chemie, Universität München, F.R.G
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12
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13
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Mattingly JR, Rodriguez-Berrocal FJ, Gordon J, Iriarte A, Martinez-Carrion M. Molecular cloning and in vivo expression of a precursor to rat mitochondrial aspartate aminotransferase. Biochem Biophys Res Commun 1987; 149:859-65. [PMID: 3322287 DOI: 10.1016/0006-291x(87)90487-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A 2.4 kilobase cDNA for rat mitochondrial aspartate aminotransferase (E.C. 2.6.1.1.) was isolated and sequenced. The predicted presequence is 93% homologous to the presequences of the enzyme from pig and mouse. The predicted amino acid sequence of the mature enzyme differs from that determined directly by amino acid sequencing (Huynh, Q.K., Sakakibara, R., Watanabe, T., and Wada, H. (1981) J. Biochem. (Tokyo) 90, 863-875) at 13 amino acids residues. The most important difference is at position 140 where the cDNA encodes a tryptophanyl residue rather than the previously reported glycine. This critical residue is now seen to be conserved in all aspartate aminotransferases. The coding region of this cDNA was inserted into the plasmid cloning vector pKK233-2 and used to stably express an unfused precursor in Escherichia coli JM105.
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Affiliation(s)
- J R Mattingly
- Division of Molecular Biology and Biochemistry, School of Basic Life Sciences, University of Missouri-Kansas City 64110
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14
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Sakakibara R, Horio Y, Ishiguro M, Kangawa K, Matsuo H, Wada H. An antibody and anti-idiotypic antibody against the extra signal peptide of pre-aspartate aminotransferase. Biochem Biophys Res Commun 1987; 148:979-88. [PMID: 2825694 DOI: 10.1016/s0006-291x(87)80228-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A peptide (extra signal peptide) comprising amino acids 1-29 of pig liver pre-mitochondrial aspartate aminotransferase (p-mAAT) was synthesized chemically. The peptide was found to block the import of rat liver p-mAAT into rat liver mitochondria. An antibody raised against the peptide immunoprecipitated rat liver p-mAAT synthesized in a rabbit reticulocyte cell-free translation system. These results suggested that the extra signal peptide sequence of p-mAAT is essential for import of p-mAAT into the mitochondria and that there is structural homology between the extra signal peptides of pig and rat liver p-mAAT. An anti-idiotypic antibody against the peptide was also prepared and purified by affinity chromatography on an Affi-Gel 10 anti-peptide IgG column and was then characterized.
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Affiliation(s)
- R Sakakibara
- Department of Biochemistry, School of Pharmaceutical Sciences, Nagasaki University, Japan
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15
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Jaussi R, Behra R, Giannattasio S, Flura T, Christen P. Expression of cDNAs encoding the precursor and the mature form of chicken mitochondrial aspartate aminotransferase in Escherichia coli. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45222-2] [Citation(s) in RCA: 13] [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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16
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Choi SY, Churchich JE. Biosynthesis of 4-aminobutyrate aminotransferase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 161:289-94. [PMID: 3780742 DOI: 10.1111/j.1432-1033.1986.tb10445.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mitochondrial 4-aminobutyrate aminotransferase was synthesized in a cell-free reticulocyte lysate using polysomal RNA isolated from pig brain. Its primary translation product has a higher molecular mass than the mature enzyme. The difference in relative molecular mass is approximately 2000 as revealed by SDS/polyacrylamide gel electrophoresis. The precursor of 4-aminobutyrate aminotransferase recognizes polyvalent antibodies raised against the mature enzyme. The precursor of 4-aminobutyrate aminotransferase binds pyridoxal-5-P and displays catalytic activity. Enzymatic activity was detected using a sensitive fluorimetric method, which is based on the formation of condensation products between succinic semialdehyde and cyclohexane-1,3-dione. It is concluded that removal of an extra peptide from the precursor is not an obligatory first step in the production of biological active species.
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17
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Sharma CP, Gehring H. The precursor of mitochondrial aspartate aminotransferase is translocated into mitochondria as apoprotein. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67360-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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