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Cui H, Kapur M, Diedrich JK, Yates JR, Ackerman SL, Schimmel P. Regulation of ex-translational activities is the primary function of the multi-tRNA synthetase complex. Nucleic Acids Res 2021; 49:3603-3616. [PMID: 33341895 PMCID: PMC8053116 DOI: 10.1093/nar/gkaa1183] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/16/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023] Open
Abstract
During mRNA translation, tRNAs are charged by aminoacyl-tRNA synthetases and subsequently used by ribosomes. A multi-enzyme aminoacyl-tRNA synthetase complex (MSC) has been proposed to increase protein synthesis efficiency by passing charged tRNAs to ribosomes. An alternative function is that the MSC repurposes specific synthetases that are released from the MSC upon cues for functions independent of translation. To explore this, we generated mammalian cells in which arginyl-tRNA synthetase and/or glutaminyl-tRNA synthetase were absent from the MSC. Protein synthesis, under a variety of stress conditions, was unchanged. Most strikingly, levels of charged tRNAArg and tRNAGln remained unchanged and no ribosome pausing was observed at codons for arginine and glutamine. Thus, increasing or regulating protein synthesis efficiency is not dependent on arginyl-tRNA synthetase and glutaminyl-tRNA synthetase in the MSC. Alternatively, and consistent with previously reported ex-translational roles requiring changes in synthetase cellular localizations, our manipulations of the MSC visibly changed localization.
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Affiliation(s)
- Haissi Cui
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Mridu Kapur
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jolene K Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Susan L Ackerman
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.,Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA
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2
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Avcilar-Kucukgoze I, Gamper H, Polte C, Ignatova Z, Kraetzner R, Shtutman M, Hou YM, Dong DW, Kashina A. tRNA Arg-Derived Fragments Can Serve as Arginine Donors for Protein Arginylation. Cell Chem Biol 2020; 27:839-849.e4. [PMID: 32553119 DOI: 10.1016/j.chembiol.2020.05.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/12/2020] [Accepted: 05/27/2020] [Indexed: 12/23/2022]
Abstract
Arginyltransferase ATE1 mediates posttranslational arginylation and plays key roles in multiple physiological processes. ATE1 utilizes arginyl (Arg)-tRNAArg as the donor of Arg, putting this reaction into a direct competition with the protein synthesis machinery. Here, we address the question of ATE1- Arg-tRNAArg specificity as a potential mechanism enabling this competition in vivo. Using in vitro arginylation assays and Ate1 knockout models, we find that, in addition to full-length tRNA, ATE1 is also able to utilize short tRNAArg fragments that bear structural resemblance to tRNA-derived fragments (tRF), a recently discovered class of small regulatory non-coding RNAs with global emerging biological role. Ate1 knockout cells show a decrease in tRFArg generation and a significant increase in the ratio of tRNAArg:tRFArg compared with wild type, suggesting a functional link between tRFArg and arginylation. We propose that generation of physiologically important tRFs can serve as a switch between translation and protein arginylation.
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Affiliation(s)
- Irem Avcilar-Kucukgoze
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Howard Gamper
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19144, USA
| | - Christine Polte
- Institute of Biochemistry and Molecular Biology, University of Hamburg, 20148 Hamburg, Germany
| | - Zoya Ignatova
- Institute of Biochemistry and Molecular Biology, University of Hamburg, 20148 Hamburg, Germany
| | - Ralph Kraetzner
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Michael Shtutman
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208, USA
| | - Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19144, USA
| | - Dawei W Dong
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anna Kashina
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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3
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Yakobov N, Debard S, Fischer F, Senger B, Becker HD. Cytosolic aminoacyl-tRNA synthetases: Unanticipated relocations for unexpected functions. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1861:387-400. [PMID: 29155070 DOI: 10.1016/j.bbagrm.2017.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 12/13/2022]
Abstract
Prokaryotic and eukaryotic cytosolic aminoacyl-tRNA synthetases (aaRSs) are essentially known for their conventional function of generating the full set of aminoacyl-tRNA species that are needed to incorporate each organism's repertoire of genetically-encoded amino acids during ribosomal translation of messenger RNAs. However, bacterial and eukaryotic cytosolic aaRSs have been shown to exhibit other essential nonconventional functions. Here we review all the subcellular compartments that prokaryotic and eukaryotic cytosolic aaRSs can reach to exert either a conventional or nontranslational role. We describe the physiological and stress conditions, the mechanisms and the signaling pathways that trigger their relocation and the new functions associated with these relocating cytosolic aaRS. Finally, given that these relocating pools of cytosolic aaRSs participate to a wide range of cellular pathways beyond translation, but equally important for cellular homeostasis, we mention some of the pathologies and diseases associated with the dis-regulation or malfunctioning of these nontranslational functions.
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Affiliation(s)
- Nathaniel Yakobov
- Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Institut de Botanique, 28 rue Goethe, 67083 Strasbourg Cedex, France
| | - Sylvain Debard
- Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Institut de Botanique, 28 rue Goethe, 67083 Strasbourg Cedex, France
| | - Frédéric Fischer
- Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Institut de Botanique, 28 rue Goethe, 67083 Strasbourg Cedex, France
| | - Bruno Senger
- Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Institut de Botanique, 28 rue Goethe, 67083 Strasbourg Cedex, France
| | - Hubert Dominique Becker
- Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, CNRS, Université de Strasbourg, Institut de Botanique, 28 rue Goethe, 67083 Strasbourg Cedex, France.
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4
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Yang F, Ji QQ, Ruan LL, Ye Q, Wang ED. The mRNA of human cytoplasmic arginyl-tRNA synthetase recruits prokaryotic ribosomes independently. J Biol Chem 2015; 289:20953-9. [PMID: 24898251 DOI: 10.1074/jbc.m114.562454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There are two isoforms of cytoplasmic arginyl-tRNA synthetase (hcArgRS) in human cells. The long form is a component of the multiple aminoacyl-tRNA synthetase complex, and the other is an N-terminal truncated form (NhcArgRS), free in the cytoplasm. It has been shown that the two forms of ArgRS arise from alternative translational initiation in a single mRNA. The short form is produced from the initiation at a downstream, in-frame AUG start codon. Interestingly, our data suggest that the alternative translational initiation of hcArgRS mRNA also takes place in Escherichia coli transformants. When the gene encoding full-length hcArgRS was overexpressed in E. coli, two forms of hcArgRS were observed. The N-terminal sequencing experiment identified that the short form was identical to the NhcArgRS in human cytoplasm. By constructing a bicistronic system, our data support that the mRNA encoding the N-terminal extension of hcArgRS has the capacity of independently recruiting E. coli ribosomes. Furthermore, two critical elements for recruiting prokaryotic ribosomes were identified, the “AGGA” core of the Shine-Dalgarno sequence and the “A-rich” sequence located just proximal to the alternative in-frame initiation site. Although the mechanisms of prokaryotic and eukaryotic translational initiation are distinct, they share some common features. The ability of the hcArgRS mRNA to recruit the prokaryotic ribosome may provide clues for shedding light on the mechanism of alternative translational initiation of hcArgRS mRNA in eukaryotic cells.
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Pang YLJ, Poruri K, Martinis SA. tRNA synthetase: tRNA aminoacylation and beyond. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:461-80. [PMID: 24706556 DOI: 10.1002/wrna.1224] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 01/14/2014] [Accepted: 02/06/2014] [Indexed: 01/20/2023]
Abstract
The aminoacyl-tRNA synthetases are prominently known for their classic function in the first step of protein synthesis, where they bear the responsibility of setting the genetic code. Each enzyme is exquisitely adapted to covalently link a single standard amino acid to its cognate set of tRNA isoacceptors. These ancient enzymes have evolved idiosyncratically to host alternate activities that go far beyond their aminoacylation role and impact a wide range of other metabolic pathways and cell signaling processes. The family of aminoacyl-tRNA synthetases has also been suggested as a remarkable scaffold to incorporate new domains that would drive evolution and the emergence of new organisms with more complex function. Because they are essential, the tRNA synthetases have served as pharmaceutical targets for drug and antibiotic development. The recent unfolding of novel important functions for this family of proteins offers new and promising pathways for therapeutic development to treat diverse human diseases.
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Affiliation(s)
- Yan Ling Joy Pang
- Department of Biochemistry, University of Illinois at Urbana, Urbana, IL, USA
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6
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Abstract
When compared to other conserved housekeeping protein families, such as ribosomal proteins, during the evolution of higher eukaryotes, aminoacyl-tRNA synthetases (aaRSs) show an apparent high propensity to add new sequences, and especially new domains. The stepwise emergence of those new domains is consistent with their involvement in a broad range of biological functions beyond protein synthesis, and correlates with the increasing biological complexity of higher organisms. These new domains have been extensively characterized based on their evolutionary origins and their sequence, structural, and functional features. While some of the domains are uniquely found in aaRSs and may have originated from nucleic acid binding motifs, others are common domain modules mediating protein-protein interactions that play a critical role in the assembly of the multi-synthetase complex (MSC). Interestingly, the MSC has emerged from a miniature complex in yeast to a large stable complex in humans. The human MSC consists of nine aaRSs (LysRS, ArgRS, GlnRS, AspRS, MetRS, IleRS, LeuRS, GluProRS, and bifunctional aaRs) and three scaffold proteins (AIMP1/p43, AIMP2/p38, and AIMP3/p18), and has a molecular weight of 1.5 million Dalton. The MSC has been proposed to have a functional dualism: facilitating protein synthesis and serving as a reservoir of non-canonical functions associated with its synthetase and non-synthetase components. Importantly, domain additions and functional expansions are not limited to the components of the MSC and are found in almost all aaRS proteins. From a structural perspective, multi-functionalities are represented by multiple conformational states. In fact, alternative conformations of aaRSs have been generated by various mechanisms from proteolysis to alternative splicing and posttranslational modifications, as well as by disease-causing mutations. Therefore, the metamorphosis between different conformational states is connected to the activation and regulation of the novel functions of aaRSs in higher eukaryotes.
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Affiliation(s)
- Min Guo
- Department of Cancer Biology, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33410, USA,
| | - Xiang-Lei Yang
- Department of Cancer Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA,
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Marion V, Sankaranarayanan S, de Theije C, van Dijk P, Lindsey P, Lamers MC, Harding HP, Ron D, Lamers WH, Köhler SE. Arginine deficiency causes runting in the suckling period by selectively activating the stress kinase GCN2. J Biol Chem 2011; 286:8866-74. [PMID: 21239484 PMCID: PMC3058991 DOI: 10.1074/jbc.m110.216119] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 01/13/2011] [Indexed: 12/18/2022] Open
Abstract
Suckling "F/A2" mice, which overexpress arginase-I in their enterocytes, develop a syndrome (hypoargininemia, reduced hair and muscle growth, impaired B-cell maturation) that resembles IGF1 deficiency. The syndrome may result from an impaired function of the GH-IGF1 axis, activation of the stress-kinase GCN2, and/or blocking of the mTORC1-signaling pathway. Arginine deficiency inhibited GH secretion and decreased liver Igf1 mRNA and plasma IGF1 concentration, but did not change muscle IGF1 concentration. GH supplementation induced Igf1 mRNA synthesis, but did not restore growth, ruling out direct involvement of the GH-IGF1 axis. In C2C12 muscle cells, arginine withdrawal activated GCN2 signaling, without impacting mTORC1 signaling. In F/A2 mice, the reduction of plasma and tissue arginine concentrations to ∼25% of wild-type values activated GCN2 signaling, but mTORC1-mediated signaling remained unaffected. Gcn2-deficient F/A2 mice suffered from hypoglycemia and died shortly after birth. Because common targets of all stress kinases (eIF2α phosphorylation, Chop mRNA expression) were not increased in these mice, the effects of arginine deficiency were solely mediated by GCN2.
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Affiliation(s)
- Vincent Marion
- From the Dept of Anatomy & Embryology and NUTRIM School for Nutrition, Toxicology, and Metabolism, and
| | | | - Chiel de Theije
- From the Dept of Anatomy & Embryology and NUTRIM School for Nutrition, Toxicology, and Metabolism, and
| | - Paul van Dijk
- From the Dept of Anatomy & Embryology and NUTRIM School for Nutrition, Toxicology, and Metabolism, and
| | - Patrick Lindsey
- the Department of Population Genetics, Genomics & Bioinformatics, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands
| | - Marinus C. Lamers
- the Max-Planck Institute of Immunobiology, P.O. Box 1169, D-79011 Freiburg, Germany
| | - Heather P. Harding
- the Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, United Kingdom, and
| | - David Ron
- the Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, United Kingdom, and
| | - Wouter H. Lamers
- From the Dept of Anatomy & Embryology and NUTRIM School for Nutrition, Toxicology, and Metabolism, and
- the AMC Liver Center, Academic Medical Center, University of Amsterdam, P.O. Box 22660, 1100 DD, Amsterdam, The Netherlands
| | - S. Eleonore Köhler
- From the Dept of Anatomy & Embryology and NUTRIM School for Nutrition, Toxicology, and Metabolism, and
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8
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Yang F, Xia X, Lei HY, Wang ED. Hemin binds to human cytoplasmic arginyl-tRNA synthetase and inhibits its catalytic activity. J Biol Chem 2010; 285:39437-46. [PMID: 20923763 DOI: 10.1074/jbc.m110.159913] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The free form of human cytoplasmic arginyl-tRNA synthetase (hcArgRS) is hypothesized to participate in ubiquitin-dependent protein degradation by offering arginyl-tRNA(Arg) to arginyl-tRNA transferase (ATE1). We investigated the effect of hemin on hcArgRS based on the fact that hemin regulates several critical proteins in the "N-end rule" protein degradation pathway. Extensive biochemical evidence has established that hemin could bind to both forms of hcArgRS in vitro. Based on the spectral changes of the Soret band on site-directed protein mutants, we identified Cys-115 as a specific axial ligand of hemin binding that is located in the Add1 domain. Hemin inhibited the catalytic activity of full-length and N-terminal 72-amino acid-truncated hcArgRSs by blocking amino acid activation. Kinetic analysis demonstrated that the K(m) values for tRNA(Arg), arginine, and ATP in the presence of hemin were not altered, but k(cat) values dramatically decreased compared with those in the absence of hemin. By comparison, the activity of prokaryotic ArgRS was not affected obviously by hemin. Gel filtration chromatography suggested that hemin induced oligomerization of both the isolated Add1 domain and the wild type enzyme, which could account for the inhibition of catalytic activity. However, the catalytic activity of an hcArgRS mutant with Cys-115 replaced by alanine (hcArgRS-C115A) was also inhibited by hemin, suggesting that hemin binding to Cys-115 is not responsible for the inhibition of enzymatic activity and that the specific binding may participate in other biological functions.
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Affiliation(s)
- Fang Yang
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
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9
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Guo M, Schimmel P, Yang XL. Functional expansion of human tRNA synthetases achieved by structural inventions. FEBS Lett 2009; 584:434-42. [PMID: 19932696 DOI: 10.1016/j.febslet.2009.11.064] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 11/17/2009] [Accepted: 11/17/2009] [Indexed: 02/06/2023]
Abstract
Known as an essential component of the translational apparatus, the aminoacyl-tRNA synthetase family catalyzes the first step reaction in protein synthesis, that is, to specifically attach each amino acid to its cognate tRNA. While preserving this essential role, tRNA synthetases developed other roles during evolution. Human tRNA synthetases, in particular, have diverse functions in different pathways involving angiogenesis, inflammation and apoptosis. The functional diversity is further illustrated in the association with various diseases through genetic mutations that do not affect aminoacylation or protein synthesis. Here we review the accumulated knowledge on how human tRNA synthetases used structural inventions to achieve functional expansions.
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Affiliation(s)
- Min Guo
- The Skaggs Institute for Chemical Biology, Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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10
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Nechushtan H, Kim S, Kay G, Razin E. Chapter 1 The Physiological Role of Lysyl tRNA Synthetase in the Immune System. Adv Immunol 2009; 103:1-27. [DOI: 10.1016/s0065-2776(09)03001-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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11
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Kyriacou SV, Deutscher MP. An important role for the multienzyme aminoacyl-tRNA synthetase complex in mammalian translation and cell growth. Mol Cell 2008; 29:419-27. [PMID: 18313381 DOI: 10.1016/j.molcel.2007.11.038] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 10/08/2007] [Accepted: 11/27/2007] [Indexed: 10/22/2022]
Abstract
In mammalian cells, aminoacyl-tRNA synthetases (aaRSs) are organized into a high-molecular-weight multisynthetase complex whose cellular function has remained a mystery. In this study, we have taken advantage of the fact that mammalian cells contain two forms of ArgRS, both products of the same gene, to investigate the complex's physiological role. The data indicate that the high-molecular-weight form of ArgRS, which is present exclusively as an integral component of the multisynthetase complex, is essential for normal protein synthesis and growth of CHO cells even when low-molecular-weight, free ArgRS is present and Arg-tRNA continues to be synthesized at close to wild-type levels. Based on these observations, we conclude that Arg-tRNA generated by the synthetase complex is a more efficient precursor for protein synthesis than Arg-tRNA generated by free ArgRS, exactly as would be predicted by the channeling model for mammalian translation.
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Affiliation(s)
- Sophia V Kyriacou
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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12
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Han JM, Lee MJ, Park SG, Lee SH, Razin E, Choi EC, Kim S. Hierarchical network between the components of the multi-tRNA synthetase complex: implications for complex formation. J Biol Chem 2006; 281:38663-7. [PMID: 17062567 DOI: 10.1074/jbc.m605211200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The macromolecular tRNA synthetase complex consists of nine different enzymes and three non-enzymatic factors. This complex was recently shown to be a novel signalosome, since many of its components are involved in signaling pathways in addition to their catalytic roles in protein synthesis. The structural organization and dynamic relationships of the components of the complex are not well understood. Here we performed a systematic depletion analysis to determine the effects of structural intimacy and the turnover of the components. The results showed that the stability of some components depended on their neighbors. Lysyl-tRNA synthetase was most independent of other components for its stability whereas it was most required for the stability of other components. Arginyl- and methionyl-tRNA synthetases had the opposite characteristics. Thus, the systematic depletion of the components revealed the functional reason for the complex formation and the assembly pattern of these multi-functional enzymes and their associated factors.
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Affiliation(s)
- Jung Min Han
- Imagene Company Biotechnology Incubating Center, Golden Helix, Seoul National University, Seoul 151-741, Korea
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13
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Zheng YG, Wei H, Ling C, Xu MG, Wang ED. Two forms of human cytoplasmic arginyl-tRNA synthetase produced from two translation initiations by a single mRNA. Biochemistry 2006; 45:1338-44. [PMID: 16430231 DOI: 10.1021/bi051675n] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human cytoplasmic arginyl-tRNA synthetase (ArgRS) is a component of a macromolecular complex consisting of at least nine tRNA synthetases and three auxiliary proteins. In mammalian cells, ArgRS is present as a free protein as well as a component of the complex. Via an alignment of ArgRSs from different vertebrates, the genes encoding full-length human cytoplasmic ArgRS and an N-terminal 72-amino acid deletion mutant (hcArgRS and DeltaNhcArgRS, respectively) were subcloned and expressed in Escherichia coli. The two ArgRS products were expressed as a soluble protein in E. coli. The level of production of DeltaNhcArgRS in E. coli and its specific activity were higher than those for hcArgRS. By Western blot analysis, using an antibody against the purified DeltaNhcArgRS, the two forms of ArgRS were detected in three human cell types. The 5'-end cDNA sequence, as confirmed by 5'RACE (5'-rapid amplification of cDNA ends), contained three start codons. Through mutation of the three codons, the two human cytoplasmic ArgRSs were found to be produced in different amounts, indicating that they resulted from two different translation initiation events. Here we show evidence that two forms of human cytoplasmic ArgRS were produced from two translational initiations by a single mRNA.
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Affiliation(s)
- Yong-Gang Zheng
- Graduate School, Chinese Academy of Sciences, Shanghai 200031, China
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14
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Guigou L, Mirande M. Determinants in tRNA for activation of arginyl-tRNA synthetase: evidence that tRNA flexibility is required for the induced-fit mechanism. Biochemistry 2006; 44:16540-8. [PMID: 16342945 DOI: 10.1021/bi051575h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Arginyl-tRNA synthetase (ArgRS) catalyzes formation of arginyl-adenylate in a tRNA-dependent reaction. Previous studies have revealed that conformational changes occur upon tRNA binding. In this study, we analyzed the sequence and structural features of tRNA that are essential to activate the catalytic center of mammalian arginyl-tRNA synthetase. Here, tRNA variants with different activator potential are presented. The three regions that are crucial for activation of ArgRS are the terminal adenosine, the D-loop, and the anticodon stem-loop of tRNA. The Add-1 N-terminal domain of ArgRS, which has the very unique property among aminoacyl-tRNA synthetases to interact with the D-loop in the corner of the convex side of tRNA, has an essential role in anchoring tRNA and participating in tRNA-induced amino acid activation. The results suggest that locking the acceptor extremity, the anticodon loop, and the D-loop of tRNA on the catalytic, anticodon-binding, and Add-1 domains of ArgRS also requires some flexibility of the tRNA molecule, provided by G:U base pairs, to achieve the productive conformation of the active site of the enzyme by induced fit.
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Affiliation(s)
- Ludovic Guigou
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette, France
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15
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de Jonge WJ, Hallemeesch MM, Kwikkers KL, Ruijter JM, de Gier-de Vries C, van Roon MA, Meijer AJ, Marescau B, de Deyn PP, Deutz NEP, Lamers WH. Overexpression of arginase I in enterocytes of transgenic mice elicits a selective arginine deficiency and affects skin, muscle, and lymphoid development. Am J Clin Nutr 2002; 76:128-40. [PMID: 12081826 DOI: 10.1093/ajcn/76.1.128] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Arginine is required for the detoxification of ammonia and the synthesis of proteins, nitric oxide, agmatine, creatine, and polyamines, and it may promote lymphocyte function. In suckling mammals, arginine is synthesized in the enterocytes of the small intestine, but this capacity is lost after weaning. OBJECTIVE We investigated the significance of intestinal arginine production for neonatal development in a murine model of chronic arginine deficiency. DESIGN Two lines of transgenic mice that express different levels of arginase I in their enterocytes were analyzed. RESULTS Both lines suffer from a selective but quantitatively different reduction in circulating arginine concentration. The degree of arginine deficiency correlated with the degree of retardation of hair and muscle growth and with the development of the lymphoid tissue, in particular Peyer's patches. Expression of arginase in all enterocytes was necessary to elicit this phenotype. Phenotypic abnormalities were reversed by daily injections of arginine but not of creatine. The expression level of the very arginine-rich skin protein trichohyalin was not affected in transgenic mice. Finally, nitric oxide synthase-deficient mice did not show any of the features of arginine deficiency. CONCLUSIONS Enterocytes are important for maintaining arginine homeostasis in neonatal mice. Graded arginine deficiency causes graded impairment of skin, muscle, and lymphoid development. The effects of arginine deficiency are not mediated by impaired synthesis of creatine or by incomplete charging of arginyl-transfer RNA.
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Affiliation(s)
- Wouter J de Jonge
- Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, Netherlands
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16
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Nathanson L, Deutscher MP. Active aminoacyl-tRNA synthetases are present in nuclei as a high molecular weight multienzyme complex. J Biol Chem 2000; 275:31559-62. [PMID: 10930398 DOI: 10.1074/jbc.c000385200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies suggest that aminoacylation of tRNA may play an important role in the transport of these molecules from the nucleus to the cytoplasm. However, there is almost no information regarding the status of active aminoacyl-tRNA synthetases within the nuclei of eukaryotic cells. Here we show that at least 13 active aminoacyl-tRNA synthetases are present in purified nuclei of both Chinese hamster ovary and rabbit kidney cells, although their steady-state levels represent only a small percentage of those found in the cytoplasm. Most interestingly, all the nuclear aminoacyl-tRNA synthetases examined can be isolated as part of a multienzyme complex that is more stable, and consequently larger, than the comparable complex isolated from the cytoplasm. These data directly demonstrate the presence of active aminoacyl-tRNA synthetases in mammalian cell nuclei. Moreover, their unexpected structural organization raises important questions about the functional significance of these multienzyme complexes and whether they might play a more direct role in nuclear to cytoplasmic transport of tRNAs.
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Affiliation(s)
- L Nathanson
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida 33136, USA
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17
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Lazard M, Agou F, Kerjan P, Mirande M. The tRNA-dependent activation of arginine by arginyl-tRNA synthetase requires inter-domain communication. J Mol Biol 2000; 302:991-1004. [PMID: 10993737 DOI: 10.1006/jmbi.2000.4102] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The tRNA-dependent amino acid activation catalyzed by mammalian arginyl-tRNA synthetase has been characterized. A conditional lethal mutant of Chinese hamster ovary cells that exhibits reduced arginyl-tRNA synthetase activity (Arg-1), and two of its derived revertants (Arg-1R4 and Arg-1R5) were analyzed at the structural and functional levels. A single nucleotide change, resulting in a Cys to Tyr substitution at position 599 of arginyl-tRNA synthetase, is responsible for the defective phenotype of the thermosensitive and arginine hyper-auxotroph Arg-1 cell line. The two revertants have a single additional mutation resulting in a Met222 to Ile change for Arg-1R4 or a Tyr506 to Ser change for Arg-1R5. The corresponding mutant enzymes were expressed in yeast and purified. The Cys599 to Tyr mutation affects both the thermal stability of arginyl-tRNA synthetase and the kinetic parameters for arginine in the ATP-PP(i) exchange and tRNA aminoacylation reactions. This mutation is located underneath the floor of the Rossmann fold catalytic domain characteristic of class 1 aminoacyl-tRNA synthetases, near the end of a long helix belonging to the alpha-helix bundle C-terminal domain distinctive of class 1a synthetases. For the Met222 to Ile revertant, there is very little effect of the mutation on the interaction of arginyl-tRNA synthetase with either of its substrates. However, this mutation increases the thermal stability of arginyl-tRNA synthetase, thereby leading to reversion of the thermosensitive phenotype by increasing the steady-state level of the enzyme in vivo. In contrast, for the Arg-1R5 cell line, reversion of the phenotype is due to an increased catalytic efficiency of the C599Y/Y506S double mutant as compared to the initial C599Y enzyme. In light of the location of the mutations in the 3D structure of the enzyme modeled using the crystal structure of the closely related yeast arginyl-tRNA synthetase, the kinetic analysis of these mutants suggests that the obligatory tRNA-induced activation of the catalytic site of arginyl-tRNA synthetase involves interdomain signal transduction via the long helices that build the tRNA-binding domain of the enzyme and link the site of interaction of the anticodon domain of tRNA to the floor of the active site.
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MESH Headings
- Acylation
- Adenosine Triphosphate/metabolism
- Amino Acid Sequence
- Animals
- Arginine/genetics
- Arginine/metabolism
- Arginine-tRNA Ligase/chemistry
- Arginine-tRNA Ligase/genetics
- Arginine-tRNA Ligase/isolation & purification
- Arginine-tRNA Ligase/metabolism
- Binding Sites
- CHO Cells
- Cloning, Molecular
- Cricetinae
- DNA, Complementary/genetics
- Enzyme Stability
- Kinetics
- Models, Molecular
- Molecular Sequence Data
- Protein Binding
- Protein Structure, Quaternary
- Protein Structure, Tertiary
- RNA, Transfer, Arg/genetics
- RNA, Transfer, Arg/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Signal Transduction
- Suppression, Genetic/genetics
- Thermodynamics
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Affiliation(s)
- M Lazard
- Laboratoire d'Enzymologie et Biochimie Structurales, UPR 9063 du Centre National de la Recherche Scientifique, Gif-sur-Yvette, 91190, France
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18
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Ko YG, Kang YS, Kim EK, Park SG, Kim S. Nucleolar localization of human methionyl-tRNA synthetase and its role in ribosomal RNA synthesis. J Cell Biol 2000; 149:567-74. [PMID: 10791971 PMCID: PMC2174846 DOI: 10.1083/jcb.149.3.567] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Human aminoacyl-tRNA synthetases (ARSs) are normally located in cytoplasm and are involved in protein synthesis. In the present work, we found that human methionyl-tRNA synthetase (MRS) was translocated to nucleolus in proliferative cells, but disappeared in quiescent cells. The nucleolar localization of MRS was triggered by various growth factors such as insulin, PDGF, and EGF. The presence of MRS in nucleoli depended on the integrity of RNA and the activity of RNA polymerase I in the nucleolus. The ribosomal RNA synthesis was specifically decreased by the treatment of anti-MRS antibody as determined by nuclear run-on assay and immunostaining with anti-Br antibody after incorporating Br-UTP into nascent RNA. Thus, human MRS plays a role in the biogenesis of rRNA in nucleoli, while it is catalytically involved in protein synthesis in cytoplasm.
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Affiliation(s)
- Young-Gyu Ko
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Young-Sun Kang
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Eun-Kyoung Kim
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Sang Gyu Park
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Sunghoon Kim
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
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19
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Park SG, Jung KH, Lee JS, Jo YJ, Motegi H, Kim S, Shiba K. Precursor of pro-apoptotic cytokine modulates aminoacylation activity of tRNA synthetase. J Biol Chem 1999; 274:16673-6. [PMID: 10358004 DOI: 10.1074/jbc.274.24.16673] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelial monocyte activating polypeptide II (EMAPII) is a cytokine that is specifically induced by apoptosis. Its precursor (pro-EMAPII) has been suggested to be identical to p43, which is associated with the multi-tRNA synthetase complex. Herein, we have demonstrated that the N-terminal domain of pro-EMAPII interacts with the N-terminal extension of human cytoplasmic arginyl-tRNA synthetase (RRS) using genetic and immunoprecipitation analyses. Aminoacylation activity of RRS was enhanced about 2.5-fold by the interaction with pro-EMAPII but not with its N- or C-terminal domains alone. The N-terminal extension of RRS was not required for enzyme activity but did mediate activity stimulation by pro-EMAPII. Pro-EMAPII reduced the apparent Km of RRS to tRNA, whereas the kcat value remained unchanged. Therefore, the precursor of EMAPII is a multi-functional protein that assists aminoacylation in normal cells and releases the functional cytokine upon apoptosis.
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Affiliation(s)
- S G Park
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Suwon, Kyunggido, 440-746, Korea
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20
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Abstract
Histidyl-tRNA synthetase (HisRS) is responsible for the synthesis of histidyl-transfer RNA, which is essential for the incorporation of histidine into proteins. This amino acid has uniquely moderate basic properties and is an important group in many catalytic functions of enzymes. A compilation of currently known primary structures of HisRS shows that the subunits of these homo-dimeric enzymes consist of 420-550 amino acid residues. This represents a relatively short chain length among aminoacyl-tRNA synthetases (aaRS), whose peptide chain sizes range from about 300 to 1100 amino acid residues. The crystal structures of HisRS from two organisms and their complexes with histidine, histidyl-adenylate and histidinol with ATP have been solved. HisRS from Escherichia coli and Thermus thermophilus are very similar dimeric enzymes consisting of three domains: the N-terminal catalytic domain containing the six-stranded antiparallel beta-sheet and the three motifs characteristic of class II aaRS, a HisRS-specific helical domain inserted between motifs 2 and 3 that may contact the acceptor stem of the tRNA, and a C-terminal alpha/beta domain that may be involved in the recognition of the anticodon stem and loop of tRNA(His). The aminoacylation reaction follows the standard two-step mechanism. HisRS also belongs to the group of aaRS that can rapidly synthesize diadenosine tetraphosphate, a compound that is suspected to be involved in several regulatory mechanisms of cell metabolism. Many analogs of histidine have been tested for their properties as substrates or inhibitors of HisRS, leading to the elucidation of structure-activity relationships concerning configuration, importance of the carboxy and amino group, and the nature of the side chain. HisRS has been found to act as a particularly important antigen in autoimmune diseases such as rheumatic arthritis or myositis. Successful attempts have been made to identify epitopes responsible for the complexation with such auto-antibodies.
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Affiliation(s)
- W Freist
- Max-Planck-Institut für experimentelle Medizin, Abteilung Molekulare Biologie Neuronaler Signale, Göttingen, Germany
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21
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Rho SB, Kim MJ, Lee JS, Seol W, Motegi H, Kim S, Shiba K. Genetic dissection of protein-protein interactions in multi-tRNA synthetase complex. Proc Natl Acad Sci U S A 1999; 96:4488-93. [PMID: 10200289 PMCID: PMC16359 DOI: 10.1073/pnas.96.8.4488] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytoplasmic aminoacyl-tRNA synthetases of higher eukaryotes acquired extra peptides in the course of their evolution. It has been thought that these appendices are related to the occurrence of the multiprotein complex consisting of at least eight different tRNA synthetase polypeptides. This complex is believed to be a signature feature of metazoans. In this study, we used multiple sequence alignments to infer the locations of the peptide appendices from human cytoplasmic tRNA synthetases found in the multisynthetase complex. The selected peptide appendices ranged from 22 aa of aspartyl-tRNA synthetase to 267 aa of methionyl-tRNA synthetase. We then made genetic constructions to investigate interactions between all 64 combinations of these peptides that were individually fused to nonsynthetase test proteins. The analyses identified 11 (10 heterologous and 1 homologous) interactions. The six peptide-dependent interactions paralleled what had been detected by crosslinking methods applied to the isolated multisynthetase complex. Thus, small peptide appendices seem to link together different synthetases into a complex. In addition, five interacting pairs that had not been detected previously were suggested from the observed peptide-dependent complexes.
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Affiliation(s)
- S B Rho
- Department of Biological Science, National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Suwon, Kyunggido 440-746, Korea
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22
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Rho SB, Lee JS, Jeong EJ, Kim KS, Kim YG, Kim S. A multifunctional repeated motif is present in human bifunctional tRNA synthetase. J Biol Chem 1998; 273:11267-73. [PMID: 9556618 DOI: 10.1074/jbc.273.18.11267] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tandem repeats located in the human bifunctional glutamyl-prolyl-tRNA synthetase (EPRS) have been found in many different eukaryotic tRNA synthetases and were previously shown to interact with another distinct repeated motifs in human isoleucyl-tRNA synthetase. Nuclear magnetic resonance and differential scanning calorimetry analyses of an isolated EPRS repeat showed that it consists of a helix-turn-helix with a melting temperature of 59 degrees C. Specific interaction of the EPRS repeats with those of isoleucyl-tRNA synthetase was confirmed by in vitro binding assays and shown to have a dissociation constant of approximately 2.9 microM. The EPRS repeats also showed the binding activity to the N-terminal motif of arginyl-tRNA synthetase as well as to various nucleic acids, including tRNA. Results of the present work suggest that the region comprising the repeated motifs of EPRS provides potential sites for interactions with various biological molecules and thus plays diverse roles in the cell.
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Affiliation(s)
- S B Rho
- Department of Biology, Sung Kyun Kwan University, 300 Chunchundong, Jangangu, Suwon, Kyunggido 440-746, Korea
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23
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Lazard M, Agou F, Cavarelli J, Latreille MT, Moras D, Mirande M. Genomic organization of the rat aspartyl-tRNA synthetase gene family: a single active gene and several retropseudogenes. Gene 1996; 180:197-205. [PMID: 8973367 DOI: 10.1016/s0378-1119(96)00455-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The genomic organization of the gene encoding rat aspartyl-tRNA synthetase (AspRS), a class II aminoacyl-tRNA synthetase (aaRS), was determined. A single active gene and several pseudogenes were isolated from a rat genomic DNA library and characterized. The active DRS1 gene encoding the rat AspRS spans approximately 60 kb and is divided into 16 exons. Exons 8-16, encoding the nt-binding domain of the synthetase, are clustered in the 3'-region of the gene, whereas exons 3, 4, and 5, encoding the anticodon-binding domain are separated by large introns (up to 15 kb) containing LINE sequences. One of the pseudogenes, psi DRS1, has a nt sequence 93% identical to that of the complete cDNA sequence of rat AspRS but several stop codons interrupt the coding sequence, thus identifying psi DRS1 to an inactive processed pseudogene. Two repetitive elements from the LINE family are inserted into psi DRS1. Calculation of nt substitution rates suggests that psi DRS1 sequences arose approximately 27 Myr ago. The other pseudogene, psi DRS2, should be more ancient. Taken together, these results clearly demonstrate that the AspRS gene family is composed of only one active gene. The availability of the gene structure of AspRS could help to clarify molecular evolution of class II aaRS.
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Affiliation(s)
- M Lazard
- Laboratoire d'Enzymologie, CNRS, Gif sur Yvette, France
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24
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Agou F, Waller JP, Mirande M. Expression of rat aspartyl-tRNA synthetase in Saccharomyces cerevisiae. Role of the NH2-terminal polypeptide extension on enzyme activity and stability. J Biol Chem 1996; 271:29295-303. [PMID: 8910590 DOI: 10.1074/jbc.271.46.29295] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cytoplasmic aspartyl-tRNA synthetase from mammals is one of the components of a multienzyme complex comprising nine synthetase activities. The presence of an amino-terminal extension composed of about 40 residues is a characteristic of the eukaryotic enzyme. We report here the expression in the yeast Saccharomyces cerevisiae of a native form of rat aspartyl-tRNA synthetase and of two truncated derivatives lacking 20 or 36 amino acid residues from their amino-terminal polypeptide extension. The three recombinant enzyme species were purified to homogeneity. They behave as alpha2 dimers and display catalytic parameters in the tRNA aminoacylation reaction identical to those determined for the native, complex-associated form of aspartyl-tRNA synthetase isolated from rat liver. Because the dimer dissociation constant of rat AspRS is much higher than that of its bacterial and yeast counterparts, we could establish a direct correlation between dissociation of the dimer and inactivation of the enzyme. Our results clearly show that the monomer is devoid of amino acid activation and tRNA aminoacylation activities, indicating that dimerization is essential to confer an active conformation on the catalytic site. The two NH2-terminal truncated derivatives were fully active, but proved to be more unstable than the recombinant native enzyme, suggesting that the polypeptide extension fulfills structural rather than catalytic requirements.
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Affiliation(s)
- F Agou
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Gif sur Yvette, France.
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25
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Girjes AA, Hobson K, Chen P, Lavin MF. Cloning and characterization of cDNA encoding a human arginyl-tRNA synthetase. Gene 1995; 164:347-50. [PMID: 7590355 DOI: 10.1016/0378-1119(95)00502-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Arginyl-tRNA synthetase (ArgRS) plays a key role in protein synthesis as part of a multienzyme complex with a number of other aminoacyl-tRNA synthetase (aaRS) enzymes. We have isolated a full-length cDNA encoding ArgRS as part of a project on complementation of radiosensitivity in human cells with an Epstein-Barr Virus (EBV) vector-based human cDNA library. DNA sequence analysis identified an open reading frame of 1983 nucleotides with 87% homology to other mammalian ArgRS genes. The deduced amino acid (aa) sequence (661 aa) showed 87.7% identity to the Chinese hamster ovary (CHO) enzyme and 37.7% identity to the homologous Escherichia coli enzyme. Northern blot analysis revealed the presence of a single mRNA species of approx. 2.2 kb. The results described here demonstrate that ArgRS is highly conserved in mammalian cells and confirm the presence of a hydrophobic N-terminal region in the higher-molecular-weight complexed form of ArgRS.
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Affiliation(s)
- A A Girjes
- Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, Bancroft Centre, Brisbane, Australia
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26
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Abstract
Lysyl-tRNA synthetase catalyses the formation of lysyl-transfer RNA, Lys-tRNA(Lys), which then is ready to insert lysine into proteins. Lysine is important for proteins since it is one of only two proteinogenic amino acids carrying an alkaline functional group. Seven genes of lysyl-tRNA synthetases have been localized in five organisms, and the nucleotide and the amino acid sequences have been established. The lysyl-tRNA synthetase molecules are of average chain lengths among the aminoacyl-tRNA synthetases, which range from about 300 to 1100 amino acids. Lysyl-tRNA synthetases act as dimers; in eukaryotes they can be localized in multienzyme complexes and can contain carbohydrates or lipids. Lysine tRNA is recognized by lysyl-tRNA synthetase via standard identity elements, namely anticodon region and acceptor stem. The aminoacylation follows the standard two-step mechanism. However the accuracy of selecting lysine against the other amino acids is less than average. The first threedimensional structure of a lysyl-tRNA synthetase worked out very recently, using the enzyme from the Escherichia coli lysU gene which binds one molecule of lysine, is similar to those of other class II synthetases. However, none of the reaction steps catalyzed by the enzyme is clarified to atomic resolution. Thus surprising findings might be possible. Lysyl-tRNA synthetase and its precursors as well as its substrates and products are targets and starting points of many regulation circuits, e.g. in multienzyme complex formation and function, dinucleoside polyphosphate synthesis, heat shock regulation, activation or deactivation by phosphorylation/dephosphorylation, inhibition by amino acid analogs, and generation of antibodies against lysyl-tRNA synthetase. None of these pathways is clarified completely.
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Affiliation(s)
- W Freist
- Max-Planck-Institut für Experimentelle Medizin, Göttingen, Germany
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27
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Evidence for similar structural organization of the multienzyme aminoacyl-tRNA synthetase complex in vivo and in vitro. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32446-8] [Citation(s) in RCA: 27] [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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28
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Kisselev LL, Wolfson AD. Aminoacyl-tRNA synthetases from higher eukaryotes. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1994; 48:83-142. [PMID: 7938555 DOI: 10.1016/s0079-6603(08)60854-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- L L Kisselev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow
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29
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Lazard M, Mirande M. Cloning and analysis of a cDNA encoding mammalian arginyl-tRNA synthetase, a component of the multisynthetase complex with a hydrophobic N-terminal extension. Gene 1993; 132:237-45. [PMID: 8224869 DOI: 10.1016/0378-1119(93)90201-d] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In mammalian cells, the nine aminoacyl-tRNA synthetases (aaRS) specific for the amino acids (aa) Glu, Pro, Ile, Leu, Met, Gln, Lys, Arg and Asp are associated within a multienzyme complex. Arginyl-tRNA synthetase (ArgRS) is characterized by the occurrence of two structurally distinct forms of that enzyme: a complexed (approximately 74 kDa) and a free (approximately 60 kDa) form. The cDNA encoding the 74-kDa species of ArgRS from Chinese hamster ovary cells has been isolated and sequenced. The deduced aa sequence shows 38% identity to the homologous bacterial enzyme but displays an N-terminal polypeptide extension composed of 73 aa, which is absent in the free form of mammalian ArgRS. Two regions of this extension are predicted to be alpha-helical, leading to the clustering of Leu and Ile residues on one side of the helices. This suggests that the N-terminal domain is involved in the assembly of the 74-kDa species of ArgRS within the multisynthetase complex through hydrophobic interactions. By using the isolated cDNA, a Northern blot analysis showed a single mRNA species. Thus, there is a possibility that the free and complexed forms of ArgRS are encoded by the same gene.
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Affiliation(s)
- M Lazard
- Laboratoire d'Enzymologie, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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30
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Ivanov LL, Martinkus Z, Kharchenko OV, Sara S, Lukoshevichius L, Prashkevichius A, El'skaya AV. Subcellular distribution and properties of rabbit liver aminoacyl-tRNA synthetases under myocardial ischemia. Mol Cell Biochem 1993; 125:105-14. [PMID: 8283966 DOI: 10.1007/bf00936439] [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: 01/29/2023]
Abstract
Subcellular distribution of aminoacyl-tRNA synthetase activities has been studied in normal rabbit liver and under experimental myocardial ischemia (EMI). An increase in the activity of a number of aminoacyl-tRNA synthetases in postmitochondrial and postribosomal supernatants from rabbit liver has been determined 12 hr after EMI. Gel chromatography of the postribosomal supernatant on Sepharose 6B shows that aminoacyl-tRNA synthetase activities are distributed among the fractions with M(r) 1.82 x 10(6), 0.84 x 10(6) (high-M(r) aminoacyl-tRNA synthetase complexes) and 0.12-0.35 x 10(6). In the case of EMI aminoacyl-tRNA synthetase activities are partly redistributed from the 1.82 x 10(6) complex into the 0.84 x 10(6) complex. The catalytic properties of both free and complex leucyl-tRNA synthetases have been compared. KM for all the substrates are the values of the same order in norm and under EMI. A decrease in some aminoacyl-tRNA synthetase activities associated with polyribosomes has been observed 12 hr after EMI. The interaction of aminoacyl-tRNA synthetases with polyribosomes stimulates the catalytic activity of some enzymes and protects them from heat inactivation in vitro. It is assumed that the changes in association of aminoacyl-tRNA synthetases with high-M(r) complexes and compartmentalization of these enzymes on polyribosomes may be related to the alteration of protein biosynthesis under myocardial ischemia.
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Affiliation(s)
- L L Ivanov
- Department of Biochemistry, Kaunas Medical Academy, Lithuania
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31
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Mirande M, Lazard M, Martinez R, Latreille MT. Engineering mammalian aspartyl-tRNA synthetase to probe structural features mediating its association with the multisynthetase complex. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 203:459-66. [PMID: 1735430 DOI: 10.1111/j.1432-1033.1992.tb16570.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Aspartyl-tRNA synthetase from higher eukaryotes is a component of a multienzyme complex comprising nine aminoacyl-tRNA synthetases. The cDNA encoding cytoplasmic rat liver aspartyl-tRNA synthetase was previously cloned and sequenced. This work reports the identification of structural features responsible for its association within the multisynthetase complex. Mutant and chimeric proteins have been expressed in mammalian cells and their structural behavior analyzed. A wild-type rat liver aspartyl-tRNA synthetase, expressed in Chinese hamster ovary (CHO) cells, associates within the complex from CHO cells, whereas a mutant enzyme with a deletion of 34 amino acids from its amino-terminal extremity does not. A chimeric enzyme, made of the amino-terminal moiety of rat liver aspartyl-tRNA synthetase fused to the catalytic domain of yeast lysyl-tRNA synthetase, has been expressed in Lys-101 cells, a CHO cell line with a temperature-sensitive lysyl-tRNA synthetase. The fusion protein is stable in vivo, does not associate within the multisynthetase complex and cannot restore normal growth of the mutant cells. These results establish that the 3.7-kDa amino-terminal moiety of mammalian aspartyl-tRNA synthetase mediates its association with the other components of the complex. In addition, the finding that yeast lysyl-tRNA synthetase cannot replace the aspartyl-tRNA synthetase component of the mammalian complex, indicates that interactions between neighbouring enzymes also play a prominent role in stabilization of this multienzyme structure and strengthened the view that the multisynthetase complex is a discrete entity with a well-defined structural organization.
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Affiliation(s)
- M Mirande
- Laboratoire d'Enzymologie du Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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32
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Huang S, Deutscher MP. The NH2-terminal extension of rat liver arginyl-tRNA synthetase is responsible for its hydrophobic properties. Biochem Biophys Res Commun 1991; 180:702-8. [PMID: 1953742 DOI: 10.1016/s0006-291x(05)81122-2] [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: 12/29/2022]
Abstract
Rat liver arginyl-tRNA synthetase is found in extracts either as a component (Mr = 72,000) of the multienzyme aminoacyl-tRNA synthetase complex or as a low molecular weight (Mr = 60,000) free protein. The two forms are thought to be identical except for an extra peptide extension at the NH2-terminus of the larger form which is required for its association with the complex, but is unessential for catalytic activity. It has been suggested that interactions among synthetases in the multienzyme complex are mediated by hydrophobic domains on these peptide extensions of the individual proteins. To test this model we have purified to homogeneity the larger form of arginyl-tRNA synthetase and compared its hydrophobicity to that of its low molecular weight counterpart. We show that whereas the smaller protein displays no hydrophobic character, the larger protein demonstrates a high degree of hydrophobicity. No lipid modification was found on the high molecular weight protein indicating that the amino acid sequence itself is responsible for its hydrophobic properties. These findings support the proposed model for synthetase association within the multienzyme complex.
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Affiliation(s)
- S Huang
- Department of Biochemistry, University of Connecticut Health Center, Farmington 06030
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33
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Mirande M. Aminoacyl-tRNA synthetase family from prokaryotes and eukaryotes: structural domains and their implications. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1991; 40:95-142. [PMID: 2031086 DOI: 10.1016/s0079-6603(08)60840-5] [Citation(s) in RCA: 200] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- M Mirande
- Laboratoire d'Enzymologie, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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Clemens MJ. Does protein phosphorylation play a role in translational control by eukaryotic aminoacyl-tRNA synthetases? Trends Biochem Sci 1990; 15:172-5. [PMID: 2193433 DOI: 10.1016/0968-0004(90)90153-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In addition to their primary role in tRNA charging, aminoacyl-tRNA synthetases can regulate protein synthesis in eukaryotic cells. Although the phosphorylation of these enzymes themselves has little effect on their catalytic activity, there may be a role for protein phosphorylation in mediating their regulatory effects.
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Affiliation(s)
- M J Clemens
- Department of Cellular and Molecular Sciences, St George's Hospital Medical School, London, UK
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Sivaram P, Deutscher MP. Free fatty acids associated with the high molecular weight aminoacyl-tRNA synthetase complex influence its structure and function. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39430-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Berbeć H, Paszkowska A. Comparison of the thermolability and hydrophobic properties of high- and low-molecular-weight forms of rabbit liver arginyl-tRNA synthetase. Mol Cell Biochem 1989; 86:125-33. [PMID: 2770710 DOI: 10.1007/bf00222612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Two preparations with arginyl-tRNA synthetase activity have been obtained from rabbit liver post-microsomal fraction: a) a high-molecular-weight containing the multienzyme aminoacyl-tRNA synthetase complex and b) a low-molecular-weight preparation containing free enzymes. Thermal inactivation of arginyl-tRNA synthetase in both preparations has been compared in a solution which was successively supplemented with tRNA, reduced glutathione, L-ascorbic acid, ZnCl2 and Triton X 100. Moreover, hydrophobic properties of both enzyme preparations have been compared. It was found that the complexed arginyl-tRNA synthetase is more stable than the free enzyme. A role of hydrophobic interactions in the maintenance of the complexed enzyme stability is suggested.
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Affiliation(s)
- H Berbeć
- Department of Physiological Chemistry, Medical School, Lublin, Poland
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Sivaram P, Vellekamp G, Deutscher MP. A role for lipids in the functional and structural properties of the rat liver aminoacyl-tRNA synthetase complex. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37366-6] [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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39
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Ciechanover A, Ferber S, Ganoth D, Elias S, Hershko A, Arfin S. Purification and characterization of arginyl-tRNA-protein transferase from rabbit reticulocytes. Its involvement in post-translational modification and degradation of acidic NH2 termini substrates of the ubiquitin pathway. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37936-5] [Citation(s) in RCA: 24] [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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40
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Construction and analysis of deletions in the amino-terminal extension of glutamine tRNA synthetase of Saccharomyces cerevisiae. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61035-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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41
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Vellekamp G, Deutscher M. A basic NH2-terminal extension of rat liver arginyl-tRNA synthetase required for its association with high molecular weight complexes. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61051-8] [Citation(s) in RCA: 19] [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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42
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Kunugi S, Uehara-Kunugi Y, von der Haar F, Schischkoff J, Freist W, Englisch U, Cramer F. Biochemical comparison of the Neurospora crassa wild type and the temperature-sensitive and leucine-auxotroph mutant leu-5. Purification of the cytoplasmic and mitochondrial leucyl-tRNA synthetases and comparison of the enzymatic activities and the degradation patterns. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 158:43-9. [PMID: 2942398 DOI: 10.1111/j.1432-1033.1986.tb09718.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The cytoplasmic leucyl-tRNA synthetases of Neurospora crassa wild type (grown at 37 degrees C) and mutant (grown at 28 degrees C) were purified approximately 1770-fold and 1440-fold respectively. Additional enzyme preparations were carried out with mutant cells grown for 24 h at 28 degrees C and transferred then to 37 degrees C for 10-70 h of growth. The mitochondrial leucyl-tRNA synthetase of the wild type was purified approximately 722-fold. The mitochondrial mutant enzyme was found only in traces. The cytoplasmic leucyl-tRNA synthetase from the mutant (grown at 37 degrees C) in vivo is subject of a proteolytic degradation. This leads to an increased pyrophosphate exchange, without altering aminoacylation. Proteolysis in vitro by trypsin or subtilisin of isolated cytoplasmic wild-type and mutant leucyl-tRNA synthetases, however, did not establish and difference in the degradation products and in their catalytic properties. Comparing the cytoplasmic wild-type and mutant enzymes (grown at 28 degrees C) via steady-state kinetics did not show significant differences between these synthetases either. The rate-determining step appears to be after the transfer of the aminoacyl group to the tRNA, e.g. a conformational change or the release of the product. Besides leucine only isoleucine is activated by the enzymes with a discrimination of approximately 1:600; however, no Ile-tRNALeu is released. Similarly these enzymes, when tested with eight ATP analogs, cannot be distinguished. For both enzymes six ATP analogs are neither substrates nor inhibitors. Two analogs are substrates with identical kinetic parameters. The mitochondrial wild-type leucyl-tRNA synthetase is different from the cytoplasmic enzyme, as particularly exhibited by aminoacylating Escherichia coli tRNALeu but not N. crassa cytoplasmic tRNALeu. The presence of traces of the analogous mitochondrial mutant enzyme could be demonstrated. Therefore, the difference between wild-type and mutant leu-5 does not rest in the catalytic properties of the cytoplasmic leucyl-tRNA synthetases. Differences in other properties of these enzymes are not excluded. In contrast the activity of the mitochondrial leucyl-tRNA synthetase of the mutant is approximately 1% of that of the wild-type enzyme.
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