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Taravella Oill AM, Buetow KH, Wilson MA. The role of Neanderthal introgression in liver cancer. BMC Med Genomics 2022; 15:255. [PMID: 36503519 PMCID: PMC9743633 DOI: 10.1186/s12920-022-01405-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/25/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Neanderthal introgressed DNA has been linked to different normal and disease traits including immunity and metabolism-two important functions that are altered in liver cancer. However, there is limited understanding of the relationship between Neanderthal introgression and liver cancer risk. The aim of this study was to investigate the relationship between Neanderthal introgression and liver cancer risk. METHODS Using germline and somatic DNA and tumor RNA from liver cancer patients from The Cancer Genome Atlas, along with ancestry-match germline DNA from unaffected individuals from the 1000 Genomes Resource, and allele specific expression data from normal liver tissue from The Genotype-Tissue Expression project we investigated whether Neanderthal introgression impacts cancer etiology. Using a previously generated set of Neanderthal alleles, we identified Neanderthal introgressed haplotypes. We then tested whether somatic mutations are enriched or depleted on Neanderthal introgressed haplotypes compared to modern haplotypes. We also computationally assessed whether somatic mutations have a functional effect or show evidence of regulating expression of Neanderthal haplotypes. Finally, we compared patterns of Neanderthal introgression in liver cancer patients and the general population. RESULTS We find Neanderthal introgressed haplotypes exhibit an excess of somatic mutations compared to modern haplotypes. Variant Effect Predictor analysis revealed that most of the somatic mutations on these Neanderthal introgressed haplotypes are not functional. We did observe expression differences of Neanderthal alleles between tumor and normal for four genes that also showed a pattern of enrichment of somatic mutations on Neanderthal haplotypes. However, gene expression was similar between liver cancer patients with modern ancestry and liver cancer patients with Neanderthal ancestry at these genes. Provocatively, when analyzing all genes, we find evidence of Neanderthal introgression regulating expression in tumor from liver cancer patients in two genes, ARK1C4 and OAS1. Finally, we find that most genes do not show a difference in the proportion of Neanderthal introgression between liver cancer patients and the general population. CONCLUSION Our results suggest that Neanderthal introgression provides opportunity for somatic mutations to accumulate, and that some Neanderthal introgression may impact liver cancer risk.
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Affiliation(s)
- Angela M Taravella Oill
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA.
- School of Life Sciences, Arizona State University, Tempe, AZ, USA.
| | - Kenneth H Buetow
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Melissa A Wilson
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
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2
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Nagaraja S, Ankri S. Utilization of Different Omic Approaches to Unravel Stress Response Mechanisms in the Parasite Entamoeba histolytica. Front Cell Infect Microbiol 2018; 8:19. [PMID: 29473019 PMCID: PMC5809450 DOI: 10.3389/fcimb.2018.00019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/16/2018] [Indexed: 12/18/2022] Open
Abstract
During its life cycle, the unicellular parasite Entamoeba histolytica is challenged by a wide variety of environmental stresses, such as fluctuation in glucose concentration, changes in gut microbiota composition, and the release of oxidative and nitrosative species from neutrophils and macrophages. The best mode of survival for this parasite is to continuously adapt itself to the dynamic environment of the host. Our ability to study the stress-induced responses and adaptive mechanisms of this parasite has been transformed through the development of genomics, proteomics or metabolomics (omics sciences). These studies provide insights into different facets of the parasite's behavior in the host. However, there is a dire need for multi-omics data integration to better understand its pathogenic nature, ultimately paving the way to identify new chemotherapeutic targets against amebiasis. This review provides an integration of the most relevant omics information on the mechanisms that are used by E. histolytica to resist environmental stresses.
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Affiliation(s)
- Shruti Nagaraja
- Department of Molecular Microbiology, Ruth and Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Serge Ankri
- Department of Molecular Microbiology, Ruth and Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel
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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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Charzewska A, Wierzba J, Iżycka-Świeszewska E, Bekiesińska-Figatowska M, Jurek M, Gintowt A, Kłosowska A, Bal J, Hoffman-Zacharska D. Hypomyelinating leukodystrophies - a molecular insight into the white matter pathology. Clin Genet 2016; 90:293-304. [DOI: 10.1111/cge.12811] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 12/23/2022]
Affiliation(s)
- A. Charzewska
- Institute of Mother and Child, Department of Medical Genetics; Warsaw Poland
| | - J. Wierzba
- Medical University of Gdańsk; Department of Paediatrics, Haemathology & Oncology, Department of General Nursery; Gdańsk Poland
| | - E. Iżycka-Świeszewska
- Medical University of Gdańsk; Department of Pathology & Neuropathology; Copernicus Hospital, Department of Patomorphology; Gdańsk Poland
| | | | - M. Jurek
- Institute of Mother and Child, Department of Medical Genetics; Warsaw Poland
| | - A. Gintowt
- Medical University of Gdańsk; Department of Biology and Genetics; Gdańsk Poland
| | - A. Kłosowska
- Medical University of Gdańsk; Department of Paediatrics, Haemathology & Oncology, Department of General Nursery; Gdańsk Poland
| | - J. Bal
- Institute of Mother and Child, Department of Medical Genetics; Warsaw Poland
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5
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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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6
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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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7
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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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8
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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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9
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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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10
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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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11
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Sissler M, Eriani G, Martin F, Giegé R, Florentz C. Mirror image alternative interaction patterns of the same tRNA with either class I arginyl-tRNA synthetase or class II aspartyl-tRNA synthetase. Nucleic Acids Res 1997; 25:4899-906. [PMID: 9396794 PMCID: PMC147145 DOI: 10.1093/nar/25.24.4899] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Gene cloning, overproduction and an efficient purification protocol of yeast arginyl-tRNA synthetase (ArgRS) as well as the interaction patterns of this protein with cognate tRNAArgand non-cognate tRNAAspare described. This work was motivated by the fact that the in vitro transcript of tRNAAspis of dual aminoacylation specificity and is not only aspartylated but also efficiently arginylated. The crystal structure of the complex between class II aspartyl-tRNA synthetase (AspRS) and tRNAAsp, as well as early biochemical data, have shown that tRNAAspis recognized by its variable region side. Here we show by footprinting with enzymatic and chemical probes that transcribed tRNAAspis contacted by class I ArgRS along the opposite D arm side, as is homologous tRNAArg, but with idiosyncratic interaction patterns. Besides protection, footprints also show enhanced accessibility of the tRNAs to the structural probes, indicative of conformational changes in the complexed tRNAs. These different patterns are interpreted in relation to the alternative arginine identity sets found in the anticodon loops of tRNAArgand tRNAAsp. The mirror image alternative interaction patterns of unmodified tRNAAspwith either class I ArgRS or class II AspRS, accounting for the dual identity of this tRNA, are discussed in relation to the class defining features of the synthetases. This study indicates that complex formation between unmodified tRNAAspand either ArgRS and AspRS is solely governed by the proteins.
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MESH Headings
- Anticodon/chemistry
- Arginine-tRNA Ligase/classification
- Arginine-tRNA Ligase/metabolism
- Aspartate-tRNA Ligase/classification
- Aspartate-tRNA Ligase/metabolism
- Base Sequence
- DNA Footprinting
- Escherichia coli
- Fungal Proteins/classification
- Fungal Proteins/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Binding
- RNA, Fungal/chemistry
- RNA, Fungal/metabolism
- RNA, Transfer, Arg/chemistry
- RNA, Transfer, Arg/metabolism
- RNA, Transfer, Asp/chemistry
- RNA, Transfer, Asp/metabolism
- Recombinant Fusion Proteins/metabolism
- Saccharomyces cerevisiae/metabolism
- Stereoisomerism
- Substrate Specificity
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Affiliation(s)
- M Sissler
- Unité Propre de Recherche 9002 'Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance', Institut de Biologie Moléculaire et Cellulaire du Centre National de la Recherche Scientifique, Strasbourg, France
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12
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Agou F, Mirande M. Aspartyl-tRNA synthetase from rat: in vitro functional analysis of its assembly into the multisynthetase complex. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 243:259-67. [PMID: 9030747 DOI: 10.1111/j.1432-1033.1997.0259a.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In mammalian cells, nine aminoacyl-tRNA synthetases, including aspartyl-tRNA synthetase, are associated within a multienzyme complex. Rat aspartyl-tRNA synthetase has a N-terminal polypeptide extension of about 40 amino acid residues which can be removed without impairing its catalytic activity. Earlier, in vivo studies showed that enzymes deprive of this N-terminal segment behave in vivo as free entities. We designed an experimental in vitro approach, based on the exchange of the complexed endogenous enzyme by free recombinant species, to assess the contribution of that domain in the association of aspartyl-tRNA synthetase to the complex. A phosphorylation site was introduced at the N-terminus of rat aspartyl-tRNA synthetase. The enzyme served as a reporter protein to evaluate the dissociation constants of native and N-terminal-truncated species towards the complex. Our data show that a moderate but significant drop in affinity is inferred by the removal of the N-terminal domain. The results suggest that this domain binds to another component of the complex, but might primarily serve a targeting function absolutely required in vivo for the assembly within the multienzyme structure.
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Affiliation(s)
- F Agou
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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13
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Rho SB, Lee KH, Kim JW, Shiba K, Jo YJ, Kim S. Interaction between human tRNA synthetases involves repeated sequence elements. Proc Natl Acad Sci U S A 1996; 93:10128-33. [PMID: 8816763 PMCID: PMC38348 DOI: 10.1073/pnas.93.19.10128] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Aminoacyl-tRNA synthetases (tRNA synthetases) of higher eukaryotes form a multiprotein complex. Sequence elements that are responsible for the protein assembly were searched by using a yeast two-hybrid system. Human cytoplasmic isoleucyl-tRNA synthetase is a component of the multi-tRNA synthetase complex and it contains a unique C-terminal appendix. This part of the protein was used as bait to identify an interacting protein from a HeLa cDNA library. The selected sequence represented the internal 317 amino acids of human bifunctional (glutamyl- and prolyl-) tRNA synthetase, which is also known to be a component of the complex. Both the C-terminal appendix of the isoleucyl-tRNA synthetase and the internal region of bifunctional tRNA synthetase comprise repeating sequence units, two repeats of about 90 amino acids, and three repeats of 57 amino acids, respectively. Each repeated motif of the two proteins was responsible for the interaction, but the stronger interaction was shown by the native structures containing multiple motifs. Interestingly, the N-terminal extension of human glycyl-tRNA synthetase containing a single motif homologous to those in the bifunctional tRNA synthetase also interacted with the C-terminal motif of the isoleucyl-tRNA synthetase although the enzyme is not a component of the complex. The data indicate that the multiplicity of the binding motif in the tRNA synthetases is necessary for enhancing the interaction strength and may be one of the determining factors for the tRNA synthetases to be involved in the formation of the multi-tRNA synthetase complex.
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Affiliation(s)
- S B Rho
- Department of Biology, Sung Kyun Kwan University, Suwon, Kyunggido, South Korea
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