1
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Kim JM, Jung J. Highly chromophoric fluorescent-labeled methionyl-initiator tRNAs applicable in living cells. Biotechnol J 2024; 19:e2300579. [PMID: 38494424 DOI: 10.1002/biot.202300579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/05/2024] [Accepted: 02/12/2024] [Indexed: 03/19/2024]
Abstract
Fluorescent initiator tRNAs (tRNAi) play a crucial role in studying protein synthesis, yet generating highly fluorescent tRNAi complexes remains challenging. We present an optimized strategy to effectively generate highly fluorescent initiator-tRNA complexes in living cells. Our strategy allows the generation of Fluo-Met-tRNAiMet complexes. These complexes can have highly chromogenic N-terminal labeling. For generating such complexes, we use either purified fluorescent methionine (PFM) or non-purified fluorescently labeled methionine (NPFM). Furthermore, PFM promotes the active generation of endogenous tRNAi in cells, leading to highly efficient Fluo-Met-tRNAiMet complexes. Finally, PFM-tRNAiMet complexes also facilitate the visualization of native fluorescently labeled Tat binding to beads. This demonstrates the potential of our approach to advance precision protein engineering and biotechnology applications.
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Affiliation(s)
- Jung Min Kim
- Ojeong Resilience Institute, Korea University, Seoul, Republic of Korea
| | - Jinho Jung
- Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
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2
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Katoh T, Suga H. Translation initiation with exotic amino acids using EF-P-responsive artificial initiator tRNA. Nucleic Acids Res 2023; 51:8169-8180. [PMID: 37334856 PMCID: PMC10450175 DOI: 10.1093/nar/gkad496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 05/10/2023] [Accepted: 06/17/2023] [Indexed: 06/21/2023] Open
Abstract
Translation initiation using noncanonical initiator substrates with poor peptidyl donor activities, such as N-acetyl-l-proline (AcPro), induces the N-terminal drop-off-reinitiation event. Thereby, the initiator tRNA drops-off from the ribosome and the translation reinitiates from the second amino acid to yield a truncated peptide lacking the N-terminal initiator substrate. In order to suppress this event for the synthesis of full-length peptides, here we have devised a chimeric initiator tRNA, referred to as tRNAiniP, whose D-arm comprises a recognition motif for EF-P, an elongation factor that accelerates peptide bond formation. We have shown that the use of tRNAiniP and EF-P enhances the incorporation of not only AcPro but also d-amino, β-amino and γ-amino acids at the N-terminus. By optimizing the translation conditions, e.g. concentrations of translation factors, codon sequence and Shine-Dalgarno sequence, we could achieve complete suppression of the N-terminal drop-off-reinitiation for the exotic amino acids and enhance the expression level of full-length peptide up to 1000-fold compared with the use of the ordinary translation conditions.
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Affiliation(s)
- Takayuki Katoh
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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3
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Jennings MD, Pavitt GD. Quantifying the Binding of Fluorescently Labeled Guanine Nucleotides and Initiator tRNA to Eukaryotic Translation Initiation Factor 2. Methods Mol Biol 2022; 2428:89-99. [PMID: 35171475 DOI: 10.1007/978-1-0716-1975-9_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The translation initiation factor eIF2 is critical for protein synthesis initiation, and its regulation is central to the integrated stress response (ISR). eIF2 is a G protein, and the activity is regulated by its GDP or GTP-binding status, such that only GTP-bound eIF2 has high affinity for initiator methionyl tRNA. In the ISR, regulatory signaling reduces the availability of eIF2-GTP and so downregulates protein synthesis initiation in cells. Fluorescence spectroscopy can be used as an analytical tool to study protein-ligand interactions in vitro. Here we describe methods to purify eIF2 and assays of its activity, employing analogs of GDP, GTP, and methionyl initiator tRNA ligands to accurately measure their binding affinities.
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Affiliation(s)
- Martin D Jennings
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.
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4
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Niland CN, Anderson DR, Jankowsky E, Harris ME. The contribution of the C5 protein subunit of Escherichia coli ribonuclease P to specificity for precursor tRNA is modulated by proximal 5' leader sequences. RNA 2017; 23:1502-1511. [PMID: 28694328 PMCID: PMC5602109 DOI: 10.1261/rna.056408.116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 06/14/2017] [Indexed: 05/03/2023]
Abstract
Recognition of RNA by RNA processing enzymes and RNA binding proteins often involves cooperation between multiple subunits. However, the interdependent contributions of RNA and protein subunits to molecular recognition by ribonucleoproteins are relatively unexplored. RNase P is an endonuclease that removes 5' leaders from precursor tRNAs and functions in bacteria as a dimer formed by a catalytic RNA subunit (P RNA) and a protein subunit (C5 in E. coli). The P RNA subunit contacts the tRNA body and proximal 5' leader sequences [N(-1) and N(-2)] while C5 binds distal 5' leader sequences [N(-3) to N(-6)]. To determine whether the contacts formed by P RNA and C5 contribute independently to specificity or exhibit cooperativity or anti-cooperativity, we compared the relative kcat/Km values for all possible combinations of the six proximal 5' leader nucleotides (n = 4096) for processing by the E. coli P RNA subunit alone and by the RNase P holoenzyme. We observed that while the P RNA subunit shows specificity for 5' leader nucleotides N(-2) and N(-1), the presence of the C5 protein reduces the contribution of P RNA to specificity, but changes specificity at N(-2) and N(-3). The results reveal that the contribution of C5 protein to RNase P processing is controlled by the identity of N(-2) in the pre-tRNA 5' leader. The data also clearly show that pairing of the 5' leader with the 3' ACCA of tRNA acts as an anti-determinant for RNase P cleavage. Comparative analysis of genomically encoded E. coli tRNAs reveals that both anti-determinants are subject to negative selection in vivo.
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Affiliation(s)
- Courtney N Niland
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - David R Anderson
- Zicklin School of Business, Baruch College, CUNY, New York, New York 10010, USA
| | - Eckhard Jankowsky
- Center for RNA Molecular Biology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Michael E Harris
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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5
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Liu Y, Li Y, Zhu C, Tian L, Guan M, Chen Y. Mitochondrial biogenesis dysfunction and metabolic dysfunction from a novel mitochondrial tRNA Met 4467 C>A mutation in a Han Chinese family with maternally inherited hypertension. Sci Rep 2017; 7:3034. [PMID: 28596595 PMCID: PMC5465199 DOI: 10.1038/s41598-017-03303-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/13/2017] [Indexed: 11/21/2022] Open
Abstract
To investigate the relationship between mitochondrial DNA (mtDNA) and hypertension as well as the mechanism involved in mitochondrial metabolic dysfunction. We identified a novel tRNAMet C4467A mutation in a Han Chinese family with hypertension. The maternal members presented with increased glucose, total cholesterol, low-density lipoprotein, and serum sodium as well as decreased potassium compared with non-maternal members (P < 0.05). Segregation analysis showed this mutation was maternally inherited. We analyzed lymphocyte cell lines derived from three maternal and three non-maternal family members. Reactive oxygen species production in the mutant cell lines was 114.5% higher compared with that in controls (P < 0.05) while ATP was 26.4% lower. The mitochondrial membrane potential of the mutated cell lines was 26.2% lower than that in controls (P < 0.05). Oxygen consumption rates were decreased in the mutant cell lines (P < 0.05). The activation of caspase-3/7 was 104.1% higher in the mutant cell lines compared with controls (P < 0.05). The expression of voltage-dependent anion channel (VDAC), Bax and apoptosis-inducing factor (AIF) in the mutant cell lines was higher compared with that in controls, with the increased colocalization of VDAC and Bax. Therefore, this mutation contributes to oxidative stress and mitochondrial biogenesis dysfunction, which may be involved in the pathogenesis of hypertension.
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Affiliation(s)
- Yuqi Liu
- Cardiac department of Chinese PLA General Hospital, Beijing, 100853, China
| | - Yang Li
- Cardiac department of Chinese PLA General Hospital, Beijing, 100853, China
- Institute of Geriatric Cardiology of Chinese PLA General Hospital, Beijing, 100853, China
| | - Chao Zhu
- Cardiac department of Chinese PLA General Hospital, Beijing, 100853, China
| | - Liuyang Tian
- Cardiac department of People's Hospital of Tianjing, Tianjing, 300121, China
| | - Minxin Guan
- Institute of Genetics, Zhejiang University and Department of Genetics, Zhejiang University, School of Medicine, Hangzhou, Zhejiang, 310058, China.
| | - Yundai Chen
- Cardiac department of Chinese PLA General Hospital, Beijing, 100853, China.
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6
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Monestier A, Aleksandrov A, Coureux PD, Panvert M, Mechulam Y, Schmitt E. The structure of an E. coli tRNA fMet A 1-U 72 variant shows an unusual conformation of the A 1-U 72 base pair. RNA 2017; 23:673-682. [PMID: 28143889 PMCID: PMC5393177 DOI: 10.1261/rna.057877.116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 01/26/2017] [Indexed: 06/06/2023]
Abstract
Translation initiation in eukaryotes and archaea involves a methionylated initiator tRNA delivered to the ribosome in a ternary complex with e/aIF2 and GTP. Eukaryotic and archaeal initiator tRNAs contain a highly conserved A1-U72 base pair at the top of the acceptor stem. The importance of this base pair to discriminate initiator tRNAs from elongator tRNAs has been established previously using genetics and biochemistry. However, no structural data illustrating how the A1-U72 base pair participates in the accurate selection of the initiator tRNAs by the translation initiation systems are available. Here, we describe the crystal structure of a mutant E. coli initiator tRNAfMetA1-U72, aminoacylated with methionine, in which the C1:A72 mismatch at the end of the tRNA acceptor stem has been changed to an A1-U72 base pair. Sequence alignments show that the mutant E. coli tRNA is a good mimic of archaeal initiator tRNAs. The crystal structure, determined at 2.8 Å resolution, shows that the A1-U72 pair adopts an unusual arrangement. A1 is in a syn conformation and forms a single H-bond interaction with U72 This interaction requires protonation of the N1 atom of A1 Moreover, the 5' phosphoryl group folds back into the major groove of the acceptor stem and interacts with the N7 atom of G2 A possible role of this unusual geometry of the A1-U72 pair in the recognition of the initiator tRNA by its partners during eukaryotic and archaeal translation initiation is discussed.
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Affiliation(s)
- Auriane Monestier
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau cedex, France
| | - Alexey Aleksandrov
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau cedex, France
| | - Pierre-Damien Coureux
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau cedex, France
| | - Michel Panvert
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau cedex, France
| | - Yves Mechulam
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau cedex, France
| | - Emmanuelle Schmitt
- Laboratoire de Biochimie, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau cedex, France
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7
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Hussain T, Llácer JL, Wimberly BT, Kieft JS, Ramakrishnan V. Large-Scale Movements of IF3 and tRNA during Bacterial Translation Initiation. Cell 2016; 167:133-144.e13. [PMID: 27662086 PMCID: PMC5037330 DOI: 10.1016/j.cell.2016.08.074] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 08/04/2016] [Accepted: 08/23/2016] [Indexed: 11/19/2022]
Abstract
In bacterial translational initiation, three initiation factors (IFs 1–3) enable the selection of initiator tRNA and the start codon in the P site of the 30S ribosomal subunit. Here, we report 11 single-particle cryo-electron microscopy (cryoEM) reconstructions of the complex of bacterial 30S subunit with initiator tRNA, mRNA, and IFs 1–3, representing different steps along the initiation pathway. IF1 provides key anchoring points for IF2 and IF3, thereby enhancing their activities. IF2 positions a domain in an extended conformation appropriate for capturing the formylmethionyl moiety charged on tRNA. IF3 and tRNA undergo large conformational changes to facilitate the accommodation of the formylmethionyl-tRNA (fMet-tRNAfMet) into the P site for start codon recognition. Structures of the 30S ribosomal subunit with initiation factors, tRNA and mRNA IF3 helps to position the correct start codon in the P site before binding of tRNA Large-scale conformational changes of IF3 and tRNA are observed IF3 movements facilitate the accommodation of initiator tRNA in P site
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Affiliation(s)
| | - Jose L Llácer
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Brian T Wimberly
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA; RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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8
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Van Laer B, Roovers M, Wauters L, Kasprzak JM, Dyzma M, Deyaert E, Kumar Singh R, Feller A, Bujnicki JM, Droogmans L, Versées W. Structural and functional insights into tRNA binding and adenosine N1-methylation by an archaeal Trm10 homologue. Nucleic Acids Res 2016; 44:940-53. [PMID: 26673726 PMCID: PMC4737155 DOI: 10.1093/nar/gkv1369] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 11/23/2015] [Accepted: 11/26/2015] [Indexed: 11/12/2022] Open
Abstract
Purine nucleosides on position 9 of eukaryal and archaeal tRNAs are frequently modified in vivo by the post-transcriptional addition of a methyl group on their N1 atom. The methyltransferase Trm10 is responsible for this modification in both these domains of life. While certain Trm10 orthologues specifically methylate either guanosine or adenosine at position 9 of tRNA, others have a dual specificity. Until now structural information about this enzyme family was only available for the catalytic SPOUT domain of Trm10 proteins that show specificity toward guanosine. Here, we present the first crystal structure of a full length Trm10 orthologue specific for adenosine, revealing next to the catalytic SPOUT domain also N- and C-terminal domains. This structure hence provides crucial insights in the tRNA binding mechanism of this unique monomeric family of SPOUT methyltransferases. Moreover, structural comparison of this adenosine-specific Trm10 orthologue with guanosine-specific Trm10 orthologues suggests that the N1 methylation of adenosine relies on additional catalytic residues.
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MESH Headings
- Adenosine/chemistry
- Adenosine/metabolism
- Archaeal Proteins/chemistry
- Archaeal Proteins/genetics
- Archaeal Proteins/metabolism
- Catalytic Domain
- Crystallography, X-Ray
- Methylation
- Models, Molecular
- Molecular Docking Simulation
- Protein Structure, Tertiary
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Scattering, Small Angle
- Sulfolobus acidocaldarius/enzymology
- X-Ray Diffraction
- tRNA Methyltransferases/chemistry
- tRNA Methyltransferases/genetics
- tRNA Methyltransferases/metabolism
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Affiliation(s)
- Bart Van Laer
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium
| | - Martine Roovers
- Institut de Recherches Microbiologiques Jean-Marie Wiame, Avenue E. Gryson 1, 1070 Bruxelles, Belgium
| | - Lina Wauters
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Department of Cell Biochemistry, University of Groningen, Nijenborgh 7, Groningen 9747 AG, Netherlands
| | - Joanna M Kasprzak
- International Institute of Molecular and Cell Biology in Warsaw, Trojdena 4 St, 02-109 Warsaw, Poland Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - Michal Dyzma
- International Institute of Molecular and Cell Biology in Warsaw, Trojdena 4 St, 02-109 Warsaw, Poland
| | - Egon Deyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium
| | - Ranjan Kumar Singh
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium
| | - André Feller
- Laboratoire de Microbiologie, Université libre de Bruxelles, 12 Rue des Professeurs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Trojdena 4 St, 02-109 Warsaw, Poland Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - Louis Droogmans
- Laboratoire de Microbiologie, Université libre de Bruxelles, 12 Rue des Professeurs Jeener et Brachet, 6041 Gosselies, Belgium
| | - Wim Versées
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium
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9
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Abstract
Initiation of mRNA translation is a major checkpoint for regulating level and fidelity of protein synthesis. Being rate limiting in protein synthesis, translation initiation also represents the target of many post-transcriptional mechanisms regulating gene expression. The process begins with the formation of an unstable 30S pre-initiation complex (30S pre-IC) containing initiation factors (IFs) IF1, IF2 and IF3, the translation initiation region of an mRNA and initiator fMet-tRNA whose codon and anticodon pair in the P-site following a first-order rearrangement of the 30S pre-IC produces a locked 30S initiation complex (30SIC); this is docked by the 50S subunit to form a 70S complex that, following several conformational changes, positional readjustments of its ligands and ejection of the IFs, becomes a 70S initiation complex productive in initiation dipeptide formation. The first EF-G-dependent translocation marks the beginning of the elongation phase of translation. Here, we review structural, mechanistic and dynamical aspects of this process.
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MESH Headings
- Bacteria/genetics
- Bacteria/metabolism
- Binding Sites/genetics
- Codon, Initiator/genetics
- Codon, Initiator/metabolism
- Models, Genetic
- Nucleic Acid Conformation
- Peptide Initiation Factors/genetics
- Peptide Initiation Factors/metabolism
- Protein Biosynthesis
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- Ribosomes/metabolism
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Affiliation(s)
| | - Cynthia L Pon
- Laboratory of Genetics, University of Camerino, 62032, Camerino, Italy.
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10
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Katibah GE, Lee HJ, Huizar JP, Vogan JM, Alber T, Collins K. tRNA binding, structure, and localization of the human interferon-induced protein IFIT5. Mol Cell 2013; 49:743-50. [PMID: 23317505 PMCID: PMC3615435 DOI: 10.1016/j.molcel.2012.12.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 12/19/2012] [Accepted: 12/20/2012] [Indexed: 10/27/2022]
Abstract
Interferon-induced proteins, including the largely uncharacterized interferon-induced tetratricopeptide repeat (IFIT) protein family, provide defenses against pathogens. Differing from expectations for tetratricopeptide repeat (TPR) proteins and from human IFIT1, IFIT2, and IFIT3, we show that human IFIT5 recognizes cellular RNA instead of protein partners. In vivo and in vitro, IFIT5 bound to endogenous 5'-phosphate-capped RNAs, including transfer RNAs. The crystal structure of IFIT5 revealed a convoluted intramolecular packing of eight TPRs as a fold that we name the TPR eddy. Additional, non-TPR structural elements contribute to an RNA binding cleft. Instead of general cytoplasmic distribution, IFIT5 concentrated in actin-rich protrusions from the apical cell surface colocalized with the RNA-binding retinoic acid-inducible gene-I (RIG-I). These findings establish compartmentalized cellular RNA binding activity as a mechanism for IFIT5 function and reveal the TPR eddy as a scaffold for RNA recognition.
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MESH Headings
- Actins/metabolism
- Amino Acid Substitution
- Animals
- Crystallography, X-Ray
- DEAD Box Protein 58
- DEAD-box RNA Helicases/chemistry
- DEAD-box RNA Helicases/isolation & purification
- DEAD-box RNA Helicases/metabolism
- HEK293 Cells
- Humans
- Mice
- Models, Molecular
- Mutagenesis, Site-Directed
- Neoplasm Proteins/chemistry
- Neoplasm Proteins/isolation & purification
- Neoplasm Proteins/metabolism
- Protein Binding
- Protein Interaction Mapping
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein Transport
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Receptors, Immunologic
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Affiliation(s)
- George E. Katibah
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Ho Jun Lee
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - John P. Huizar
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Jacob M. Vogan
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Tom Alber
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute of Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
| | - Kathleen Collins
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute of Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
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11
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Koehler C, Round A, Simader H, Suck D, Svergun D. Quaternary structure of the yeast Arc1p-aminoacyl-tRNA synthetase complex in solution and its compaction upon binding of tRNAs. Nucleic Acids Res 2013; 41:667-76. [PMID: 23161686 PMCID: PMC3592460 DOI: 10.1093/nar/gks1072] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 10/08/2012] [Accepted: 10/13/2012] [Indexed: 11/16/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, the aminoacyl-tRNA synthetases (aaRS) GluRS and MetRS form a complex with the auxiliary protein cofactor Arc1p. The latter binds the N-terminal domains of both synthetases increasing their affinity for the transfer-RNA (tRNA) substrates tRNA(Met) and tRNA(Glu). Until now, structural information was available only on the enzymatic domains of the individual aaRSs but not on their complexes with associated cofactors. We have analysed the yeast Arc1p-complexes in solution by small-angle X-ray scattering (SAXS). The ternary complex of MetRS and GluRS with Arc1p, displays a peculiar extended star-like shape, implying possible flexibility of the complex. We reconstituted in vitro a pentameric complex and demonstrated by electrophoretic mobility shift assay that the complex is active and contains tRNA(Met) and tRNA(Glu), in addition to the three protein partners. SAXS reveals that binding of the tRNAs leads to a dramatic compaction of the pentameric complex compared to the ternary one. A hybrid low-resolution model of the pentameric complex is constructed rationalizing the compaction effect by the interactions of negatively charged tRNA backbones with the positively charged tRNA-binding domains of the synthetases.
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MESH Headings
- Electrophoretic Mobility Shift Assay
- Glutamate-tRNA Ligase/chemistry
- Glutamate-tRNA Ligase/metabolism
- Methionine-tRNA Ligase/chemistry
- Methionine-tRNA Ligase/metabolism
- Models, Molecular
- Protein Structure, Tertiary
- RNA, Transfer, Glu/chemistry
- RNA, Transfer, Glu/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/metabolism
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/metabolism
- Scattering, Small Angle
- X-Ray Diffraction
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Affiliation(s)
- Christine Koehler
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, 69117, Germany, EMBL UVHCI, Grenoble, Cedex 9, 38042, France, Proteros Biostructure, Martinsried-München, 82152 and EMBL Outstation Hamburg, c/o/DESY, European Molecular Biology Laboratory, Hamburg, 22603, Germany
| | - Adam Round
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, 69117, Germany, EMBL UVHCI, Grenoble, Cedex 9, 38042, France, Proteros Biostructure, Martinsried-München, 82152 and EMBL Outstation Hamburg, c/o/DESY, European Molecular Biology Laboratory, Hamburg, 22603, Germany
| | - Hannes Simader
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, 69117, Germany, EMBL UVHCI, Grenoble, Cedex 9, 38042, France, Proteros Biostructure, Martinsried-München, 82152 and EMBL Outstation Hamburg, c/o/DESY, European Molecular Biology Laboratory, Hamburg, 22603, Germany
| | - Dietrich Suck
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, 69117, Germany, EMBL UVHCI, Grenoble, Cedex 9, 38042, France, Proteros Biostructure, Martinsried-München, 82152 and EMBL Outstation Hamburg, c/o/DESY, European Molecular Biology Laboratory, Hamburg, 22603, Germany
| | - Dmitri Svergun
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, 69117, Germany, EMBL UVHCI, Grenoble, Cedex 9, 38042, France, Proteros Biostructure, Martinsried-München, 82152 and EMBL Outstation Hamburg, c/o/DESY, European Molecular Biology Laboratory, Hamburg, 22603, Germany
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12
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Naveau M, Lazennec-Schurdevin C, Panvert M, Dubiez E, Mechulam Y, Schmitt E. Roles of yeast eIF2α and eIF2β subunits in the binding of the initiator methionyl-tRNA. Nucleic Acids Res 2013; 41:1047-57. [PMID: 23193270 PMCID: PMC3553985 DOI: 10.1093/nar/gks1180] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 10/19/2012] [Accepted: 10/26/2012] [Indexed: 01/09/2023] Open
Abstract
Heterotrimeric eukaryotic/archaeal translation initiation factor 2 (e/aIF2) binds initiator methionyl-tRNA and plays a key role in the selection of the start codon on messenger RNA. tRNA binding was extensively studied in the archaeal system. The γ subunit is able to bind tRNA, but the α subunit is required to reach high affinity whereas the β subunit has only a minor role. In Saccharomyces cerevisiae however, the available data suggest an opposite scenario with β having the most important contribution to tRNA-binding affinity. In order to overcome difficulties with purification of the yeast eIF2γ subunit, we designed chimeric eIF2 by assembling yeast α and β subunits to archaeal γ subunit. We show that the β subunit of yeast has indeed an important role, with the eukaryote-specific N- and C-terminal domains being necessary to obtain full tRNA-binding affinity. The α subunit apparently has a modest contribution. However, the positive effect of α on tRNA binding can be progressively increased upon shortening the acidic C-terminal extension. These results, together with small angle X-ray scattering experiments, support the idea that in yeast eIF2, the tRNA molecule is bound by the α subunit in a manner similar to that observed in the archaeal aIF2-GDPNP-tRNA complex.
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Affiliation(s)
| | | | | | | | | | - Emmanuelle Schmitt
- Laboratoire de Biochimie, Unité mixte de Recherche 7654, Ecole Polytechnique, Centre National de la Recherche Scientifique, F-91128 Palaiseau Cedex, France
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13
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Ishida K, Kunibayashi T, Tomikawa C, Ochi A, Kanai T, Hirata A, Iwashita C, Hori H. Pseudouridine at position 55 in tRNA controls the contents of other modified nucleotides for low-temperature adaptation in the extreme-thermophilic eubacterium Thermus thermophilus. Nucleic Acids Res 2011; 39:2304-18. [PMID: 21097467 PMCID: PMC3064792 DOI: 10.1093/nar/gkq1180] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/02/2010] [Accepted: 11/02/2010] [Indexed: 11/13/2022] Open
Abstract
Pseudouridine at position 55 (Ψ55) in eubacterial tRNA is produced by TruB. To clarify the role of the Ψ55 modification, we constructed a truB gene disruptant (ΔtruB) strain of Thermus thermophilus which is an extreme-thermophilic eubacterium. Unexpectedly, the ΔtruB strain exhibited severe growth retardation at 50 °C. We assumed that these phenomena might be caused by lack of RNA chaperone activity of TruB, which was previously hypothetically proposed by others. To confirm this idea, we replaced the truB gene in the genome with mutant genes, which express TruB proteins with very weak or no enzymatic activity. However the growth retardation at 50 °C was not rescued by these mutant proteins. Nucleoside analysis revealed that Gm18, m(5)s(2)U54 and m(1)A58 in tRNA from the ΔtruB strain were abnormally increased. An in vitro assay using purified tRNA modification enzymes demonstrated that the Ψ55 modification has a negative effect on Gm18 formation by TrmH. These experimental results show that the Ψ55 modification is required for low-temperature adaptation to control other modified. (35)S-Met incorporation analysis showed that the protein synthesis activity of the ΔtruB strain was inferior to that of the wild-type strain and that the cold-shock proteins were absence in the ΔtruB cells at 50°C.
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Affiliation(s)
- Kazuo Ishida
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Takashi Kunibayashi
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Chie Tomikawa
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Anna Ochi
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Tamotsu Kanai
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Akira Hirata
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Chikako Iwashita
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
| | - Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Venture Business Laboratory, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577 and RIKEN SPring-8 Center, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyougo 679-5148, Japan
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14
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Pan D, Qin H, Cooperman BS. Synthesis and functional activity of tRNAs labeled with fluorescent hydrazides in the D-loop. RNA 2009; 15:346-354. [PMID: 19118261 PMCID: PMC2648706 DOI: 10.1261/rna.1257509] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 10/24/2008] [Indexed: 05/27/2023]
Abstract
We describe an optimized procedure for replacing the dihydrouridine residues of charged tRNAs with Cy3 and Cy5 dyes linked to a hydrazide group, and demonstrate that the labeled molecules are functional in ribosomal activities including 30S initiation complex formation, EF-Tu-dependent binding to the ribosome, translocation, and polypeptide synthesis. This procedure should be straightforwardly generalizable to the incorporation of other hydrazide-linked fluorophores into tRNA or other dihydrouridine-containing RNAs. In addition, we use a rapid turnover FRET experiment, measuring energy transfer between Cy5-labeled tRNA(fMet) and Cy3-labeled fMetPhe-tRNA(Phe), to obtain direct evidence supporting the hypothesis that the early steps of translocation involve movements of the flexible 3'-single-stranded regions of the tRNAs, with the considerable increase in the distance separating the two tRNA tertiary cores occurring later in the process.
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MESH Headings
- Carbocyanines/chemistry
- Fluorescence Resonance Energy Transfer
- Fluorescent Dyes/chemistry
- Methods
- Nucleic Acid Conformation
- Peptide Elongation Factor Tu/metabolism
- Peptides/metabolism
- Poly U/metabolism
- Protein Biosynthesis
- RNA, Fungal/chemical synthesis
- RNA, Fungal/chemistry
- RNA, Transfer/chemical synthesis
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer, Amino Acyl/chemical synthesis
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Met/chemical synthesis
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Ribosome Subunits, Small/metabolism
- Uridine/chemistry
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Affiliation(s)
- Dongli Pan
- Department of Chemistry, University of Pennsylvania, Philadelphia, 19104-6323, USA
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15
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Rodriguez-Correa D, Dahlberg AE. Kinetic and thermodynamic studies of peptidyltransferase in ribosomes from the extreme thermophile Thermus thermophilus. RNA 2008; 14:2314-2318. [PMID: 18824514 PMCID: PMC2578854 DOI: 10.1261/rna.1146008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 08/12/2008] [Indexed: 05/26/2023]
Abstract
Throughout evolution, emerging organisms survived by adapting existing biochemical processes to new reaction conditions. Simple protein enzymes balanced changes in structural stability with changes that permitted optimal catalysis by adjustments in both entropic and enthalpic contributions to the free energy of activation for the reaction. Study of adaptive mechanisms by large multicomponent enzymes such as the ribosome has been largely unexplored. Here we have determined the kinetic and thermodynamic parameters of peptidyltransferase in ribosomes from the extreme thermophile Thermus thermophilus. Activity of thermophilic enzymes can be assayed over a wide range of temperatures, enabling one to measure accurate catalytic rates and determine enthalpic and entropic contributions to the free energy of activation of the reaction. Differences in the reaction conditions used here and in published studies on mesophilic ribosomes prevent direct comparison, but our data on Thermus ribosomes suggest that these ribosomes have adapted to changing environments using the same strategies as simple protein enzymes, balancing stability and flexibility without loss of catalytic rate. This strategy must be a very ancient process, perhaps first used by primitive ribosomes in the RNA World.
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Affiliation(s)
- Daniel Rodriguez-Correa
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island 02912, USA
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16
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Kolupaeva VG, de Breyne S, Pestova TV, Hellen CUT. In vitro reconstitution and biochemical characterization of translation initiation by internal ribosomal entry. Methods Enzymol 2008; 430:409-39. [PMID: 17913647 DOI: 10.1016/s0076-6879(07)30016-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The internal ribosomal entry sites (IRESs) of encephalomyocarditis virus (EMCV) and related viruses promote initiation of translation by a noncanonical end-independent mechanism. To characterize this mechanism at the molecular level, we have developed biochemical approaches to reconstitute the process in vitro from individual purified components of the translation apparatus, developed methods to characterize steps in this process so that the functions of individual proteins can be characterized, and adapted assays such as primer extension inhibition ("toe printing") to monitor accurate assembly on the IRES of ribosomal 48S and 80S complexes. In vitro reconstitution of 48S complex formation offers an approach for the functional identification of IRES trans-acting factors (ITAFs) that are required for initiation in addition to canonical initiation factors and revealed that despite being related, different EMCV-like IRESs nevertheless have distinct ITAF requirements. Toe printing revealed that a common feature of initiation on EMCV-like IRESs is the stable binding of an eIF4G/eIF4A complex to them near the initiation codon, where it can locally unwind RNA to facilitate ribosomal attachment. The same toe printing assay indicated that binding of ITAFs to these IRESs enhances binding of these two canonical initiation factors. We also describe protocols for chemical and enzymatic footprinting to determine the interactions of trans-acting factors with the IRES at nucleotide resolution and for directed hydroxyl radical probing to determine their orientation on the IRES.
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MESH Headings
- Base Sequence
- Cell-Free System
- Eukaryotic Initiation Factors/chemistry
- Eukaryotic Initiation Factors/genetics
- Eukaryotic Initiation Factors/metabolism
- Humans
- Hydroxyl Radical/chemistry
- Macromolecular Substances
- Molecular Sequence Data
- Nucleic Acid Conformation
- Peptide Chain Initiation, Translational
- Plasmids/genetics
- Plasmids/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
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Affiliation(s)
- Victoria G Kolupaeva
- Department of Microbiology and Immunology, State University of New York Downstate Medical Center, Brooklyn, USA
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17
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Huggins W, Shapkina T, Wollenzien P. Conformational energy and structure in canonical and noncanonical forms of tRNA determined by temperature analysis of the rate of s(4)U8-C13 photocrosslinking. RNA 2007; 13:2000-11. [PMID: 17872510 PMCID: PMC2040084 DOI: 10.1261/rna.656907] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Bacterial tRNAs frequently have 4-thiouridine (s(4)U) modification at position 8, which is adjacent to the C13-G22-m(7)G46 base triple in the elbow region of the tRNA tertiary structure. Irradiation with light in the UVA range induces an efficient photocrosslink between s(4)U8 and C13. The temperature dependence of the rate constants for photocrosslinking between the s(4)U8 and C13 has been used to investigate the tRNA conformational energy and structure in Escherichia coli tRNA(Val), tRNA(Phe), and tRNA(fMet) under different conditions. Corrections have been made in the measured rate constants to compensate for differences in the excited state lifetimes due to tRNA identity, buffer conditions, and temperature. The resulting rate constants are related to the rate at which the s(4)U8 and C13 come into the alignment needed for photoreaction; this depends on an activation energy, attributable to the conformational potential energy that occurs during the photoreaction, and on the extent of the structural change. Different photocrosslinking rate constants and temperature dependencies occur in the three tRNAs, and these differences are due both to modest differences in the activation energies and in the apparent s(4)U8-C13 geometries. Analysis of tRNA(Val) in buffers without Mg(2+) indicate a smaller activation energy (~13 kJ mol(-1)) and a larger apparent s(4)U8-C13 distance (~12 A) compared to values for the same parameters in buffers with Mg(2+) (~26 kJ mol(-1) and 0.36 A, respectively). These measurements are a quantitative indication of the strong constraint that Mg(2+) imposes on the tRNA flexibility and structure.
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Affiliation(s)
- Wayne Huggins
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
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18
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Abergel C, Rudinger-Thirion J, Giegé R, Claverie JM. Virus-encoded aminoacyl-tRNA synthetases: structural and functional characterization of mimivirus TyrRS and MetRS. J Virol 2007; 81:12406-17. [PMID: 17855524 PMCID: PMC2169003 DOI: 10.1128/jvi.01107-07] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 09/04/2007] [Indexed: 11/20/2022] Open
Abstract
Aminoacyl-tRNA synthetases are pivotal in determining how the genetic code is translated in amino acids and in providing the substrate for protein synthesis. As such, they fulfill a key role in a process universally conserved in all cellular organisms from their most complex to their most reduced parasitic forms. In contrast, even complex viruses were not found to encode much translation machinery, with the exception of isolated components such as tRNAs. In this context, the discovery of four aminoacyl-tRNA synthetases encoded in the genome of mimivirus together with a full set of translation initiation, elongation, and termination factors appeared to blur what was once a clear frontier between the cellular and viral world. Functional studies of two mimivirus tRNA synthetases confirmed the MetRS specificity for methionine and the TyrRS specificity for tyrosine and conformity with the identity rules for tRNA(Tyr) for archea/eukarya. The atomic structure of the mimivirus tyrosyl-tRNA synthetase in complex with tyrosinol exhibits the typical fold and active-site organization of archaeal-type TyrRS. However, the viral enzyme presents a unique dimeric conformation and significant differences in its anticodon binding site. The present work suggests that mimivirus aminoacyl-tRNA synthetases function as regular translation enzymes in infected amoebas. Their phylogenetic classification does not suggest that they have been acquired recently by horizontal gene transfer from a cellular host but rather militates in favor of an intricate evolutionary relationship between large DNA viruses and ancestral eukaryotes.
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MESH Headings
- Acanthamoeba/virology
- Animals
- Anticodon/chemistry
- Anticodon/metabolism
- Crystallography, X-Ray
- DNA Viruses/enzymology
- Methionine-tRNA Ligase/chemistry
- Methionine-tRNA Ligase/classification
- Methionine-tRNA Ligase/genetics
- Phylogeny
- Protein Structure, Secondary
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- RNA, Transfer, Tyr/chemistry
- RNA, Transfer, Tyr/metabolism
- Tyrosine-tRNA Ligase/chemistry
- Tyrosine-tRNA Ligase/classification
- Tyrosine-tRNA Ligase/genetics
- Viral Proteins/chemistry
- Viral Proteins/classification
- Viral Proteins/genetics
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Affiliation(s)
- Chantal Abergel
- Structural and Genomic Information Laboratory, CNRS-UPR2589, IBSM-IFR88, 163 Avenue de Luminy, Case 934, 13288, Marseille Cedex 9, France.
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19
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Ghosh A, Vishveshwara S. A study of communication pathways in methionyl- tRNA synthetase by molecular dynamics simulations and structure network analysis. Proc Natl Acad Sci U S A 2007; 104:15711-6. [PMID: 17898174 PMCID: PMC2000407 DOI: 10.1073/pnas.0704459104] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The enzymes of the family of tRNA synthetases perform their functions with high precision by synchronously recognizing the anticodon region and the aminoacylation region, which are separated by approximately 70 A in space. This precision in function is brought about by establishing good communication paths between the two regions. We have modeled the structure of the complex consisting of Escherichia coli methionyl-tRNA synthetase (MetRS), tRNA, and the activated methionine. Molecular dynamics simulations have been performed on the modeled structure to obtain the equilibrated structure of the complex and the cross-correlations between the residues in MetRS have been evaluated. Furthermore, the network analysis on these simulated structures has been carried out to elucidate the paths of communication between the activation site and the anticodon recognition site. This study has provided the detailed paths of communication, which are consistent with experimental results. Similar studies also have been carried out on the complexes (MetRS + activated methonine) and (MetRS + tRNA) along with ligand-free native enzyme. A comparison of the paths derived from the four simulations clearly has shown that the communication path is strongly correlated and unique to the enzyme complex, which is bound to both the tRNA and the activated methionine. The details of the method of our investigation and the biological implications of the results are presented in this article. The method developed here also could be used to investigate any protein system where the function takes place through long-distance communication.
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Affiliation(s)
- Amit Ghosh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Saraswathi Vishveshwara
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
- *To whom correspondence may be addressed. E-mail:
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20
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Nikonov O, Stolboushkina E, Nikulin A, Hasenöhrl D, Bläsi U, Manstein DJ, Fedorov R, Garber M, Nikonov S. New insights into the interactions of the translation initiation factor 2 from archaea with guanine nucleotides and initiator tRNA. J Mol Biol 2007; 373:328-36. [PMID: 17825838 DOI: 10.1016/j.jmb.2007.07.048] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 07/11/2007] [Accepted: 07/20/2007] [Indexed: 10/23/2022]
Abstract
Heterotrimeric a/eIF2alphabetagamma (archaeal homologue of the eukaryotic translation initiation factor 2 with alpha, beta and gamma subunits) delivers charged initiator tRNA (tRNAi) to the small ribosomal subunit. In this work, we determined the structures of aIF2gamma from the archaeon Sulfolobus solfataricus in the nucleotide-free and GDP-bound forms. Comparison of the free, GDP and Gpp(NH)p-Mg2+ forms of aIF2gamma revealed a sequence of conformational changes upon GDP and GTP binding. Our results show that the affinity of GDP to the G domain of the gamma subunit is higher than that of Gpp(NH)p. In analyzing a pyrophosphate molecule binding to domain II of the gamma subunit, we found a cleft that is very suitable for the acceptor stem of tRNA accommodation. It allows the suggestion of an alternative position for Met-tRNA i Met on the alphagamma intersubunit dimer, at variance with a recently published one. In the model reported here, the acceptor stem of the tRNAi is approximately perpendicular to that of tRNA in the ternary complex elongation factor Tu-Gpp(NH)p-tRNA. According to our analysis, the elbow and T stem of Met-tRNA i Met in this position should make extensive contact with the alpha subunit of aIF2. Thus, this model is in good agreement with experimental data showing that the alpha subunit of aIF2 is necessary for the stable interaction of aIF2gamma with Met-tRNA i Met.
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Affiliation(s)
- Oleg Nikonov
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russian Federation.
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21
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Abstract
Initiation of translation is defined as the process by which a 40S ribosomal subunit, containing bound initiator methionyl-tRNA (Met-tRNA(i)), is positioned at the initiation AUG codon of an mRNA to form the 48S initiation complex. Subsequently, a 60S ribosomal subunit joins the 48S initiation complex to form an elongation-competent 80S initiation complex. By use of highly purified eukaryotic translation initiation factors (eIFs), ribosomes, Met-tRNA(i), mRNA, GTP as an effector molecule, and ATP as a source of energy, the initiation step of translation can be efficiently reconstituted. In this chapter, we describe the detailed procedure for efficient binding of Met-tRNA(i) to the 40S ribosomal subunit, the subsequent binding of the resulting 43S preinitiation complex to an mRNA, and scanning and positioning of the 43S complex at the AUG start codon of the mRNA to form the 48S initiation complex.
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Affiliation(s)
- Romit Majumdar
- Department of Cell Biology, Albert Einstein College of Medicine of Yeshiva University, Jack and Pearl Resnick Campus, Bronx, New York, USA
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22
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Milon P, Konevega AL, Peske F, Fabbretti A, Gualerzi CO, Rodnina MV. Transient kinetics, fluorescence, and FRET in studies of initiation of translation in bacteria. Methods Enzymol 2007; 430:1-30. [PMID: 17913632 DOI: 10.1016/s0076-6879(07)30001-3] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Initiation of mRNA translation in prokaryotes requires the small ribosomal subunit (30S), initiator fMet-tRNA(fMet), three initiation factors, IF1, IF2, and IF3, and the large ribosomal subunit (50S). During initiation, the 30S subunit, in a complex with IF3, binds mRNA, IF1, IF2.GTP, and fMet-tRNA(fMet) to form a 30S initiation complex which then recruits the 50S subunit to yield a 70S initiation complex, while the initiation factors are released. Here we describe a transient kinetic approach to study the timing of elemental steps of 30S initiation complex formation, 50S subunit joining, and the dissociation of the initiation factors from the 70S initiation complex. Labeling of ribosomal subunits, fMet-tRNA(fMet), mRNA, and initiation factors with fluorescent reporter groups allows for the direct observation of the formation or dissociation of complexes by monitoring changes in the fluorescence of single dyes or fluorescence resonance energy transfer (FRET) between two fluorophores. Subunit joining was monitored by light scattering or by FRET between dyes attached to the ribosomal subunits. The kinetics of chemical steps, that is, GTP hydrolysis by IF2 and peptide bond formation following the binding of aminoacyl-tRNA to the 70S initiation complex, were measured by the quench-flow technique. The methods described here are based on results obtained with initiation components from Escherichia coli but can be adopted for mechanistic studies of initiation in other prokaryotic or eukaryotic systems.
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MESH Headings
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Fluorescence Resonance Energy Transfer
- GTP Phosphohydrolases/metabolism
- Models, Molecular
- Prokaryotic Initiation Factors/chemistry
- Prokaryotic Initiation Factors/genetics
- Prokaryotic Initiation Factors/metabolism
- Protein Biosynthesis
- Protein Structure, Quaternary
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Ribosome Subunits, Small, Bacterial/chemistry
- Ribosome Subunits, Small, Bacterial/genetics
- Ribosome Subunits, Small, Bacterial/metabolism
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Affiliation(s)
- Pohl Milon
- Laboratory of Genetics, Department of Biology MCA, University of Camerino, Camerino, Italy
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23
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Abstract
Bioactive peptides isolated from natural sources have diverse acyl groups on the N-terminus. It is difficult to synthesize these peptides in vitro translation system because ribosomal peptide synthesis generally limits the N-terminal group to be N-formylmethionine (fMet). To overcome this restriction, we developed a novel methodology for the ribosomal synthesis of peptides having various terminal N-acyl groups with desired amino acids. In this methodology, two technologies, Flexizyme system consisting of artificial ribozymes and a reconstitute E. coli cell-free translation system (PURE system), were used. First, an amino acid carrying a desired N-acyl group was charged onto an initiation tRNA by the Flexizyme system. The addition of this N-acyl-aminoacyl-tRNA (N-acyl-aa-tRNA) to the PURE system allowed us to initiate the peptide synthesis with the designated N-acyl-amino acid. By means of this methodology, the translation was exclusively initiated by various N-terminal acyl groups as well as amino acids without contamination of N-formylmethionine.
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MESH Headings
- Aminoacylation
- Cell-Free System
- Escherichia coli/genetics
- Peptide Chain Initiation, Translational
- Peptides/chemistry
- Phenylalanine/analogs & derivatives
- RNA, Catalytic/metabolism
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Transfer RNA Aminoacylation
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Affiliation(s)
- Yuki Goto
- Research Center of Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Tokyo, Japan
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24
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Sakurai M, Watanabe YI, Watanabe K, Ohtsuki T. A protein extension to shorten RNA: elongated elongation factor-Tu recognizes the D-arm of T-armless tRNAs in nematode mitochondria. Biochem J 2006; 399:249-56. [PMID: 16859488 PMCID: PMC1609916 DOI: 10.1042/bj20060781] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Nematode mitochondria possess extremely truncated tRNAs. Of 22 tRNAs, 20 lack the entire T-arm. The T-arm is necessary for the binding of canonical tRNAs and EF (elongation factor)-Tu (thermo-unstable). The nematode mitochondrial translation system employs two different EF-Tu factors named EF-Tu1 and EF-Tu2. Our previous study showed that nematode Caenorhabditis elegans EF-Tu1 binds specifically to T-armless tRNA. C. elegans EF-Tu1 has a 57-amino acid C-terminal extension that is absent from canonical EF-Tu, and the T-arm-binding residues of canonical EF-Tu are not conserved. In this study, the recognition mechanism of T-armless tRNA by EF-Tu1 was investigated. Both modification interference assays and primer extension analysis of cross-linked ternary complexes revealed that EF-Tu1 interacts not only with the tRNA acceptor stem but also with the D-arm. This is the first example of an EF-Tu recognizing the D-arm of a tRNA. The binding activity of EF-Tu1 was impaired by deletion of only 14 residues from the C-terminus, indicating that the C-terminus of EF-Tu1 is required for its binding to T-armless tRNA. These results suggest that C. elegans EF-Tu1 recognizes the D-arm instead of the T-arm by a mechanism involving its C-terminal region. This study sheds light on the co-evolution of RNA and RNA-binding proteins in nematode mitochondria.
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Affiliation(s)
- Masayuki Sakurai
- *Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
- †Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yoh-ichi Watanabe
- ‡Department of Biomedical Chemistry, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kimitsuna Watanabe
- *Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Takashi Ohtsuki
- *Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
- To whom correspondence should be addressed (email ). Present address: Department of Bioscience and Biotechnology, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan
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25
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Abstract
The crystal structure of the bacterial 70S ribosome refined to 2.8 angstrom resolution reveals atomic details of its interactions with messenger RNA (mRNA) and transfer RNA (tRNA). A metal ion stabilizes a kink in the mRNA that demarcates the boundary between A and P sites, which is potentially important to prevent slippage of mRNA. Metal ions also stabilize the intersubunit interface. The interactions of E-site tRNA with the 50S subunit have both similarities and differences compared to those in the archaeal ribosome. The structure also rationalizes much biochemical and genetic data on translation.
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MESH Headings
- Anticodon
- Bacterial Proteins/chemistry
- Bacterial Proteins/metabolism
- Codon
- Crystallization
- Crystallography, X-Ray
- Magnesium/metabolism
- Models, Molecular
- Nucleic Acid Conformation
- Peptidyl Transferases/chemistry
- Peptidyl Transferases/metabolism
- Protein Biosynthesis
- Protein Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- RNA, Transfer, Phe/chemistry
- RNA, Transfer, Phe/metabolism
- Ribosomal Proteins/chemistry
- Ribosomal Proteins/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
- Ribosomes/ultrastructure
- Thermus thermophilus/chemistry
- Thermus thermophilus/ultrastructure
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Affiliation(s)
- Maria Selmer
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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26
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Sokabe M, Yao M, Sakai N, Toya S, Tanaka I. Structure of archaeal translational initiation factor 2 betagamma-GDP reveals significant conformational change of the beta-subunit and switch 1 region. Proc Natl Acad Sci U S A 2006; 103:13016-21. [PMID: 16924118 PMCID: PMC1559745 DOI: 10.1073/pnas.0604165103] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Archaeal/eukaryotic initiation factor 2 (a/eIF2) consists of alpha-, beta-, and gamma-subunits and delivers initiator methionine tRNA (Met-tRNA(i)) to a small ribosomal subunit in a GTP-dependent manner. The structures of the aIF2betagamma (archaeal initiation factor 2 betagamma) heterodimeric complex in the apo and GDP forms were analyzed at 2.8- and 3.4-A resolution, respectively. The results showed that the N-terminal helix and the central helix-turn-helix domain of the beta-subunit bind to the G domain of the gamma-subunit but are distant from domains 2 and 3, to which the alpha-subunit and Met-tRNA(i) bind. This result is consistent with most of the previous analyses of eukaryotic factors, and thus indicates that the binding mode is essentially conserved among a/eIF2. Comparison with the uncomplexed structure showed significant differences between the two forms of the beta-subunit, particularly the C-terminal zinc-binding domain, which does not interact with the gamma-subunit and was suggested previously to be involved in GTP hydrolysis. Furthermore, the switch 1 region in the gamma-subunit, which is shown to be responsible for Met-tRNA(i) binding by mutational analysis, is moved away from the nucleotide through the interaction with highly conserved R87 in the beta-subunit. These results implicate that conformational change of the beta-subunit facilitates GTP hydrolysis by inducing the conformational change of the switch 1 region toward the off state.
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Affiliation(s)
- Masaaki Sokabe
- *Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan; and
| | - Min Yao
- *Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan; and
- RIKEN Harima Institute/SPring-8, Hyogo 679-5148, Japan
| | - Naoki Sakai
- *Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan; and
| | - Shingo Toya
- *Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan; and
| | - Isao Tanaka
- *Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan; and
- To whom correspondence should be addressed. E-mail:
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27
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Lescrinier E, Nauwelaerts K, Zanier K, Poesen K, Sattler M, Herdewijn P. The naturally occurring N6-threonyl adenine in anticodon loop of Schizosaccharomyces pombe tRNAi causes formation of a unique U-turn motif. Nucleic Acids Res 2006; 34:2878-86. [PMID: 16738127 PMCID: PMC1474066 DOI: 10.1093/nar/gkl081] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Modified nucleosides play an important role in structure and function of tRNA. We have determined the solution structure of the anticodon stem-loop (ASL) of initiator tRNA of Schizosaccharomyces pombe. The incorporation of N6-threonylcarbamoyladenosine at the position 3' to the anticodon triplet (t6A37) results in the formation of a U-turn motif and enhances stacking interactions within the loop and stem regions (i.e. between A35 and t6A37) by bulging out U36. This conformation was not observed in a crystal structure of tRNAi including the same modification in its anticodon loop, nor in the solution structure of the unmodified ASL. A t6A modification also occurs in the well studied anti-stem-loop of lys-tRNA(UUU). A comparison of this stem-loop with our structure demonstrates different effects of the modification depending on the loop sequence.
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Affiliation(s)
| | | | - Katia Zanier
- EMBL, Structural & Computational Biology and Gene ExpressionMeyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Koen Poesen
- EMBL, Structural & Computational Biology and Gene ExpressionMeyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Michael Sattler
- EMBL, Structural & Computational Biology and Gene ExpressionMeyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Piet Herdewijn
- To whom correspondence should be addressed. Tel: +32 0 16 337387; Fax: +32 0 16 337340;
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28
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Phelps SS, Gaudin C, Yoshizawa S, Benitez C, Fourmy D, Joseph S. Translocation of a tRNA with an extended anticodon through the ribosome. J Mol Biol 2006; 360:610-22. [PMID: 16787653 DOI: 10.1016/j.jmb.2006.05.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 05/04/2006] [Accepted: 05/04/2006] [Indexed: 11/18/2022]
Abstract
Coordinated translocation of the tRNA-mRNA complex by the ribosome occurs in a precise, stepwise movement corresponding to a distance of three nucleotides along the mRNA. Frameshift suppressor tRNAs generally contain an extra nucleotide in the anticodon loop and they subvert the normal mechanisms used by the ribosome for frame maintenance. The mechanism by which suppressor tRNAs traverse the ribosome during translocation is poorly understood. Here, we demonstrate translocation of a tRNA by four nucleotides from the A site to the P site, and from the P site to the E site. We show that translocation of a punctuated mRNA is possible with an extra, unpaired nucleotide between codons. Interestingly, the NMR structure of the four nucleotide anticodon stem-loop reveals a conformation different from the canonical tRNA structure. Flexibility within the loop may allow conformational adjustment upon A site binding and for interacting with the four nucleotide codon in order to shift the mRNA reading frame.
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MESH Headings
- Anticodon/genetics
- Anticodon/metabolism
- Base Sequence
- Escherichia coli
- Hydrogen-Ion Concentration
- Molecular Sequence Data
- Nuclear Magnetic Resonance, Biomolecular
- Nucleic Acid Conformation/drug effects
- Pliability/drug effects
- Protein Biosynthesis
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- RNA, Transfer, Phe/chemistry
- RNA, Transfer, Phe/genetics
- RNA, Transfer, Phe/metabolism
- RNA, Transfer, Val/chemistry
- RNA, Transfer, Val/genetics
- RNA, Transfer, Val/metabolism
- Reading Frames/genetics
- Ribosomes/genetics
- Ribosomes/metabolism
- Salts/pharmacology
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Affiliation(s)
- Steven S Phelps
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0314, USA
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29
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Abstract
All three kingdoms of life employ two methionine tRNAs, one for translation initiation and the other for insertion of methionines at internal positions within growing polypeptide chains. We have used a reconstituted yeast translation initiation system to explore the interactions of the initiator tRNA with the translation initiation machinery. Our data indicate that in addition to its previously characterized role in binding of the initiator tRNA to eukaryotic initiation factor 2 (eIF2), the initiator-specific A1:U72 base pair at the top of the acceptor stem is important for the binding of the eIF2.GTP.Met-tRNA(i) ternary complex to the 40S ribosomal subunit. We have also shown that the initiator-specific G:C base pairs in the anticodon stem of the initiator tRNA are required for the strong thermodynamic coupling between binding of the ternary complex and mRNA to the ribosome. This coupling reflects interactions that occur within the complex upon recognition of the start codon, suggesting that these initiator-specific G:C pairs influence this step. The effect of these anticodon stem identity elements is influenced by bases in the T loop of the tRNA, suggesting that conformational coupling between the D-loop-T-loop substructure and the anticodon stem of the initiator tRNA may occur during AUG codon selection in the ribosomal P-site, similar to the conformational coupling that occurs in A-site tRNAs engaged in mRNA decoding during the elongation phase of protein synthesis.
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MESH Headings
- Base Sequence
- Conserved Sequence
- Eukaryotic Initiation Factor-1/isolation & purification
- Eukaryotic Initiation Factor-1/metabolism
- Eukaryotic Initiation Factor-2/isolation & purification
- Eukaryotic Initiation Factor-2/metabolism
- Eukaryotic Initiation Factor-5/isolation & purification
- Eukaryotic Initiation Factor-5/metabolism
- Eukaryotic Initiation Factors/isolation & purification
- Eukaryotic Initiation Factors/metabolism
- Guanosine Triphosphate/metabolism
- Molecular Sequence Data
- Mutation
- Nucleic Acid Conformation
- Peptide Chain Initiation, Translational
- Protein Biosynthesis
- Protein Structure, Tertiary
- Puromycin/analogs & derivatives
- Puromycin/analysis
- Puromycin/biosynthesis
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/isolation & purification
- RNA, Transfer, Met/metabolism
- Ribosomes/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- Lee D Kapp
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205-2185, USA
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30
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Feinberg JS, Joseph S. Ribose 2'-hydroxyl groups in the 5' strand of the acceptor arm of P-site tRNA are not essential for EF-G catalyzed translocation. RNA 2006; 12:580-8. [PMID: 16489185 PMCID: PMC1421097 DOI: 10.1261/rna.2290706] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The coupled movement of tRNA-mRNA complex through the ribosome is a fundamental step during the protein elongation process. We demonstrate that the ribosome will translocate a P-site-bound tRNA(Met) with a break in the phosphodiester backbone between positions 17 and 18 in the D-loop. Crystallographic data showed that the acceptor arms of P- and E-site tRNA interact extensively with the ribosomal large subunit. Therefore, we used this fragmented P-site-bound tRNA(Met) to investigate the contributions of single 2'-hydroxyl groups in the 5' strand of the acceptor arm for translocation into the ribosomal E-site. EF-G-dependent translocation of the tRNAs was monitored using a toeprinting assay and a fluorescence-based rapid kinetic method. Surprisingly, our results show that none of the 2'-hydroxyl groups in the 5' strand of the acceptor arm of P-site-bound tRNA(Met) between positions 1-17 play a critical role during translocation. This suggests that either these 2'-hydroxyl groups are not important for translocation or they are redundant and the three-dimensional shape of the P-site tRNA is more important for translocation.
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Affiliation(s)
- Jason S Feinberg
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0314, USA
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31
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Pan D, Kirillov S, Zhang CM, Hou YM, Cooperman BS. Rapid ribosomal translocation depends on the conserved 18-55 base pair in P-site transfer RNA. Nat Struct Mol Biol 2006; 13:354-9. [PMID: 16532005 DOI: 10.1038/nsmb1074] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Accepted: 02/14/2006] [Indexed: 11/09/2022]
Abstract
The L shape of tRNA is stabilized by the 'tertiary core' region, which contains base-pairing interactions between the D and T loops. Distortions of the L shape accompany tRNA movement across the ribosomal surface. Here, using single-turnover rapid kinetics assays, we determine the effects of mutations within the tertiary core of P site-bound tRNA(fMet) on three measures of the rate of translocation, the part of the elongation cycle involving the most extensive tRNA movement. Mutations in the strictly conserved G18.U55 base pair result in as much as an 80-fold decrease in the rate of translocation, demonstrating the importance of the 18-55 interaction for rapid translocation. This implicates the core region as a locus for functionally important dynamic interactions with the ribosome and leads to the proposal that translocation of ribosome-bound tRNAs may be sequential rather than concerted.
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MESH Headings
- Base Pairing
- Conserved Sequence
- Escherichia coli/genetics
- Escherichia coli/metabolism
- GTP Phosphohydrolases/metabolism
- Kinetics
- Models, Biological
- Models, Molecular
- Mutation
- Nucleic Acid Conformation
- RNA Stability
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- Ribosomes/metabolism
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Affiliation(s)
- Dongli Pan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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32
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Kadaba S, Wang X, Anderson JT. Nuclear RNA surveillance in Saccharomyces cerevisiae: Trf4p-dependent polyadenylation of nascent hypomethylated tRNA and an aberrant form of 5S rRNA. RNA 2006; 12:508-21. [PMID: 16431988 PMCID: PMC1383588 DOI: 10.1261/rna.2305406] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
1-Methyladenosine modification at position 58 of tRNA is catalyzed by a two-subunit methyltransferase composed of Trm6p and Trm61p in Saccharomyces cerevisiae. Initiator tRNA (tRNAi(Met)) lacking m1A58 (hypomethylated) is rendered unstable through the cooperative function of the poly(A) polymerases, Trf4p/Trf5p, and the nuclear exosome. We provide evidence that a catalytically active Trf4p poly(A) polymerase is required for polyadenylation of hypomethylated tRNAi(Met) in vivo. DNA sequence analysis of tRNAi(Met) cDNAs and Northern hybridizations of poly(A)+ RNA provide evidence that nascent pre-tRNAi(Met) transcripts are targeted for polyadenylation and degradation. We determined that a mutant U6 snRNA and an aberrant form of 5S rRNA are stabilized in the absence of Trf4p, supporting that Trf4p facilitated RNA surveillance is a global process that stretches beyond hypomethylated tRNAi(Met). We conclude that an array of RNA polymerase III transcripts are targeted for Trf4p/ Trf5p-dependent polyadenylation and turnover to eliminate mutant and variant forms of normally stable RNAs.
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MESH Headings
- Base Sequence
- Catalytic Domain/genetics
- DNA, Fungal/genetics
- DNA-Directed DNA Polymerase/genetics
- DNA-Directed DNA Polymerase/metabolism
- DNA-Directed RNA Polymerases/genetics
- DNA-Directed RNA Polymerases/metabolism
- Methylation
- Mutagenesis, Site-Directed
- RNA Precursors/chemistry
- RNA Precursors/genetics
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Ribosomal, 5S/chemistry
- RNA, Ribosomal, 5S/genetics
- RNA, Ribosomal, 5S/metabolism
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
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Affiliation(s)
- Sujatha Kadaba
- Department of Biological Sciences, Marquette University, P.O. Box 1881, Wehr Life Sciences, Milwaukee, WI 53201, USA
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33
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Myasnikov AG, Marzi S, Simonetti A, Giuliodori AM, Gualerzi CO, Yusupova G, Yusupov M, Klaholz BP. Conformational transition of initiation factor 2 from the GTP- to GDP-bound state visualized on the ribosome. Nat Struct Mol Biol 2005; 12:1145-9. [PMID: 16284619 DOI: 10.1038/nsmb1012] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Accepted: 10/03/2005] [Indexed: 11/08/2022]
Abstract
Initiation of protein synthesis is a universally conserved event that requires initiation factors IF1, IF2 and IF3 in prokaryotes. IF2 is a GTPase essential for binding initiator transfer RNA to the 30S ribosomal subunit and recruiting the 50S subunit into the 70S initiation complex. We present two cryo-EM structures of the assembled 70S initiation complex comprising mRNA, fMet-tRNA(fMet) and IF2 with either a non-hydrolyzable GTP analog or GDP. Transition from the GTP-bound to the GDP-bound state involves substantial conformational changes of IF2 and of the entire ribosome. In the GTP analog-bound state, IF2 interacts mostly with the 30S subunit and extends to the initiator tRNA in the peptidyl (P) site, whereas in the GDP-bound state IF2 steps back and adopts a 'ready-to-leave' conformation. Our data also provide insights into the molecular mechanism guiding release of IF1 and IF3.
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Affiliation(s)
- Alexander G Myasnikov
- Department of Structural Biology and Genomics, Institute of Genetics and Molecular and Cellular Biology, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale, Université Louis Pasteur, Illkirch, France
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34
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Nakanishi K, Ogiso Y, Nakama T, Fukai S, Nureki O. Structural basis for anticodon recognition by methionyl-tRNA synthetase. Nat Struct Mol Biol 2005; 12:931-2. [PMID: 16155581 DOI: 10.1038/nsmb988] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Accepted: 08/04/2005] [Indexed: 11/09/2022]
Abstract
In the 2.7-A resolution crystal structure of methionyl-tRNA synthetase (MetRS) in complex with tRNA(Met) and a methionyl-adenylate analog, the tRNA anticodon loop is distorted to form a triple-base stack comprising C34, A35 and A38. A tryptophan residue stacks on C34 to extend the triple-base stack. In addition, C34 forms Watson-Crick-type hydrogen bonds with Arg357. This structure resolves the longstanding question of how MetRS specifically recognizes tRNA(Met).
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Affiliation(s)
- Kotaro Nakanishi
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan
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35
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Garofalo C, Kramer G, Appling DR. Characterization of the C2 subdomain of yeast mitochondrial initiation factor 2. Arch Biochem Biophys 2005; 439:113-20. [PMID: 15935987 DOI: 10.1016/j.abb.2005.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Revised: 04/26/2005] [Accepted: 05/02/2005] [Indexed: 11/20/2022]
Abstract
The COOH-terminal part of the yeast mitochondrial initiation factor 2 (ymIF2), containing the C2 subdomain, was expressed and purified as a histidine-tagged polypeptide of 137 amino acids. Like the recombinant full-length protein, the C2 subdomain binds both formyl-Met-tRNA(f)(Met) and unformylated Met-tRNA(f)(Met) with only a small preference for the former species. Formation of a binary complex between the C2 subdomain or the full-length ymIF2 and initiator tRNA was also assessed by fluorescence measurements. The binding of coumarin-Met-tRNA(f) to either protein caused a blue shift of the coumarin emission spectrum and an increase in anisotropy. Full-length ymIF2 is functionally competent in forming an initiation complex and supporting formation of the first peptide bond on Escherichia coli ribosomes. The results demonstrate that ymIF2 has the same domain structure and biochemical properties of a typical IF2 species as found in bacteria or mammalian mitochondria--but with enhanced ability to bind unformylated initiator Met-tRNA.
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Affiliation(s)
- Cristiana Garofalo
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA
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36
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Abstract
Methodology based on tRNA mediated protein engineering is described for the introduction of fluorophores and other labels at the N-terminus of proteins produced in cell-free translation systems. One method for low-level (trace) N-terminal labeling is based on the use of an Escherichia coli initiator tRNA(fMet) misaminoacylated with methionine modified at the alpha-amino group. In addition to the normal formyl group, the protein translational machinery incorporates the fluorophore BODIPY-FL and the affinity tag biotin at an N-terminal end of the nascent protein. A second method for higher N-terminal labeling uses a chemically aminoacylated amber initiator suppressor tRNA and a DNA template which contains a complementary amber (UAG) codon instead of the normal initiation (AUG) codon. This more versatile approach is demonstrated using a variety of N-terminal markers including fluorescein, biotin, PC-biotin, and a novel dual marker conjugate (Biotin/BODIPY-FL).
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Affiliation(s)
- Jerzy Olejnik
- AmberGen, 1106 Commonwealth Avenue, Boston, MA 02215, USA
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37
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Jenner L, Romby P, Rees B, Schulze-Briese C, Springer M, Ehresmann C, Ehresmann B, Moras D, Yusupova G, Yusupov M. Translational operator of mRNA on the ribosome: how repressor proteins exclude ribosome binding. Science 2005; 308:120-3. [PMID: 15802605 DOI: 10.1126/science.1105639] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The ribosome of Thermus thermophilus was cocrystallized with initiator transfer RNA (tRNA) and a structured messenger RNA (mRNA) carrying a translational operator. The path of the mRNA was defined at 5.5 angstroms resolution by comparing it with either the crystal structure of the same ribosomal complex lacking mRNA or with an unstructured mRNA. A precise ribosomal environment positions the operator stem-loop structure perpendicular to the surface of the ribosome on the platform of the 30S subunit. The binding of the operator and of the initiator tRNA occurs on the ribosome with an unoccupied tRNA exit site, which is expected for an initiation complex. The positioning of the regulatory domain of the operator relative to the ribosome elucidates the molecular mechanism by which the bound repressor switches off translation. Our data suggest a general way in which mRNA control elements must be placed on the ribosome to perform their regulatory task.
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MESH Headings
- Bacterial Proteins/metabolism
- Base Pairing
- Binding Sites
- Crystallization
- Crystallography, X-Ray
- Fourier Analysis
- Models, Molecular
- Nucleic Acid Conformation
- Protein Biosynthesis
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Regulatory Sequences, Ribonucleic Acid
- Repressor Proteins/metabolism
- Ribosomal Proteins/metabolism
- Ribosomes/metabolism
- Thermus thermophilus/genetics
- Thermus thermophilus/metabolism
- Threonine-tRNA Ligase/genetics
- Threonine-tRNA Ligase/metabolism
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Affiliation(s)
- Lasse Jenner
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
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38
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Laforest MJ, Delage L, Maréchal-Drouard L. The T-domain of cytosolic tRNAVal, an essential determinant for mitochondrial import. FEBS Lett 2005; 579:1072-8. [PMID: 15710393 DOI: 10.1016/j.febslet.2004.12.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 12/06/2004] [Accepted: 12/28/2004] [Indexed: 11/17/2022]
Abstract
Import of tRNAs into plant mitochondria appears to be highly specific. We recently showed that the anticodon and the D-domain sequences are essential determinants for tRNAVal import into tobacco cell mitochondria. To determine the minimal set of elements required to direct import of a cytosol-specific tRNA species, tobacco cells were transformed with an Arabidopsis thaliana intron-containing tRNAMet-e gene carrying the D-domain and the anticodon of a valine tRNA. Although well expressed and processed into tobacco cells, this mutated tRNA was shown to remain in the cytosol. Furthermore, a mutant tRNAVal carrying the T-domain of the tRNAMet-e, although still efficiently recognized by the valyl-tRNA synthetase, is not imported into mitochondria. Altogether these results suggest that mutations affecting the core of a tRNA molecule also alter its import ability into plant mitochondria.
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MESH Headings
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Base Sequence
- Cell Line
- Gene Expression Regulation, Plant
- Introns/genetics
- Kinetics
- Mitochondria/genetics
- Mitochondria/metabolism
- Molecular Sequence Data
- Mutation/genetics
- Nucleic Acid Conformation
- Plants, Genetically Modified
- RNA Splice Sites/genetics
- RNA Transport
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- Nicotiana
- Transcription, Genetic/genetics
- Transfer RNA Aminoacylation
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Affiliation(s)
- Marie-Josée Laforest
- Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université Louis Pasteur, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France
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39
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Gutiérrez P, Osborne MJ, Siddiqui N, Trempe JF, Arrowsmith C, Gehring K. Structure of the archaeal translation initiation factor aIF2 beta from Methanobacterium thermoautotrophicum: implications for translation initiation. Protein Sci 2004; 13:659-67. [PMID: 14978306 PMCID: PMC2286745 DOI: 10.1110/ps.03506604] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
aIF2 beta is the archaeal homolog of eIF2 beta, a member of the eIF2 heterotrimeric complex, implicated in the delivery of Met-tRNA(i)(Met) to the 40S ribosomal subunit. We have determined the solution structure of the intact beta-subunit of aIF2 from Methanobacterium thermoautotrophicum. aIF2 beta is composed of an unfolded N terminus, a mixed alpha/beta core domain and a C-terminal zinc finger. NMR data shows the two folded domains display restricted mobility with respect to each other. Analysis of the aIF2 gamma structure docked to tRNA allowed the identification of a putative binding site for the beta-subunit in the ternary translation complex. Based on structural similarity and biochemical data, a role for the different secondary structure elements is suggested.
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MESH Headings
- Amino Acid Sequence
- Archaeal Proteins/chemistry
- Archaeal Proteins/genetics
- Archaeal Proteins/metabolism
- Binding Sites/genetics
- Cloning, Molecular
- Databases, Protein
- Guanosine Triphosphate/chemistry
- Guanosine Triphosphate/metabolism
- Methanobacterium/chemistry
- Methanobacterium/genetics
- Models, Molecular
- Molecular Sequence Data
- Nuclear Magnetic Resonance, Biomolecular
- Peptide Chain Initiation, Translational
- Peptide Initiation Factors/chemistry
- Peptide Initiation Factors/genetics
- Peptide Initiation Factors/metabolism
- Protein Binding
- Protein Conformation
- Protein Structure, Secondary
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- Recombinant Proteins/chemistry
- Sequence Homology, Amino Acid
- Static Electricity
- Structural Homology, Protein
- Zinc Fingers/genetics
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Affiliation(s)
- Pablo Gutiérrez
- McGill University, Department of Biochemistry, McIntyre Medical Science Building, 3655 Promenade Sir William Osler, Montréal, Québec H3G 1Y6, Canada
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40
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Abstract
Human mitochondrial methionyl-tRNA synthetase (human mtMetRS) has been identified from the human EST database. The cDNA encodes a 593 amino acid protein with an 18 amino acid mitochondrial import signal sequence. Sequence analysis indicates that this protein contains the consensus motifs characteristic of a class I aminoacyl-tRNA synthetase but lacks the Zn(2+) binding motif and C-terminal dimerization region found in MetRSs from various organisms. The mature form of human mtMetRS has been cloned and expressed in Escherichia coli. Gel filtration experiments indicate that this protein functions as a monomer with an apparent molecular mass of 67 kDa. The kinetic parameters for activation of methionine have been determined for the purified enzyme. The K(M) and k(cat) for aminoacylation of E. coli initiator tRNA(f)(Met) are reported. The kinetics of aminoacylation of an in vitro transcript of human mitochondrial tRNA(Met) (mtRNA(Met)) have been determined. To address the effects of the modification of mtRNA on recognition of the mitochondrial tRNA by human mtMetRS, the kinetics of aminoacylation of native bovine mtRNA(Met) and of an in vitro transcript of the bovine mtRNA(Met) have also been investigated.
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Affiliation(s)
- Angela C Spencer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
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41
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Abstract
Crystallographic studies suggest that the esterified amino acid of aminoacyl tRNA make contacts with the ribosomal A-site but not in the P-site. Biochemical evidence indicating a thermodynamic contribution of the esterified amino acid to binding aminoacyl-tRNA to either the ribosomal P- and A-sites has been inconsistent, partly because of the labile nature of the aminoacyl linkage and the long times required to reach equilibrium. Measuring the association and dissociation rates of deacylated and aminoacylated tRNAs to the A-site and P-site of E. coli ribosomes afforded an accurate estimate of the contribution of the amino acid. While esterified phenylalanine or methionine has no effect on the affinity of tRNA to the P-site, an esterified pheylalanine stabilizes binding to the A-site by 7 kJ/mol, in agreement with the contacts observed in the X-ray crystal structure. In addition, it was shown that the presence of an esterified amino acid in one ribosomal site does not affect the binding of an aa-tRNA to the other site.
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MESH Headings
- Acylation
- Amino Acids/chemistry
- Amino Acids/metabolism
- Base Sequence
- Binding Sites
- Esterification
- Kinetics
- Models, Molecular
- Nucleic Acid Conformation
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- RNA, Transfer, Phe/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
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Affiliation(s)
- Richard P Fahlman
- The Department of Biochemistry, Molecular Biology & Cell Biology, Northwestern University, 2205 Tech Dr., 2-100 Hogan Hall, Evanston, Illinois 60208, USA
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42
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Crausaz Esseiva A, Maréchal-Drouard L, Cosset A, Schneider A. The T-stem determines the cytosolic or mitochondrial localization of trypanosomal tRNAsMet. Mol Biol Cell 2004; 15:2750-7. [PMID: 15064351 PMCID: PMC420099 DOI: 10.1091/mbc.e03-11-0821] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The mitochondrion of Trypanosoma brucei lacks tRNA genes. Organellar translation therefore depends on import of cytosolic, nucleus-encoded tRNAs. Except for the cytosol-specific initiator tRNA(Met), all trypanosomal tRNAs function in both the cytosol and the mitochondrion. The initiator tRNA(Met) is closely related to the imported elongator tRNA(Met). Thus, the distinct localization of the two tRNAs(Met) must be specified by the 26 nucleotides, which differ between the two molecules. Using transgenic T. brucei cell lines and subsequent cell fractionation, we show that the T-stem is both required and sufficient to specify the localization of the tRNAs(Met). Furthermore, it was shown that the tRNA(Met) T-stem localization determinants are also functional in the context of two other tRNAs. In vivo analysis of the modified nucleotides found in the initiator tRNA(Met) indicates that the T-stem localization determinants do not require modified nucleotides. In contrast, import of native tRNAs(Met) into isolated mitochondria suggests that nucleotide modifications might be involved in regulating the extent of import of elongator tRNA(Met).
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Affiliation(s)
- Anne Crausaz Esseiva
- Department of Biology/Zoology, University of Fribourg, CH-1700 Fribourg, Switzerland
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43
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Abstract
Eukaryotic translation initiation factor 2 (eIF2) is a G-protein that functions as a central switch in the initiation of protein synthesis. In its GTP-bound state it delivers the methionyl initiator tRNA (Met-tRNA(i)) to the small ribosomal subunit and releases it upon GTP hydrolysis following the recognition of the initiation codon. We have developed a complete thermodynamic framework for the assembly of the Saccharomyces cerevisiae eIF2.GTP.Met-tRNA(i) ternary complex and have determined the effect of the conversion of GTP to GDP on eIF2's affinity for Met-tRNA(i) in solution. In its GTP-bound state the factor forms a positive interaction with the methionine moiety on Met-tRNA(i) that is disrupted when GTP is replaced with GDP, while contacts between the factor and the body of the tRNA remain intact. This positive interaction with the methionine residue on the tRNA may serve to ensure that only charged initiator tRNA enters the initiation pathway. The toggling on and off of the factor's interaction with the methionine residue is likely to play an important role in the mechanism of initiator tRNA release upon initiation codon recognition. In addition, we show that the conserved base-pair A1:U72, which is known to be a critical identity element distinguishing initiator from elongator methionyl tRNA, is required for recognition of the methionine moiety by eIF2. Our data suggest that a role of this base-pair is to orient the methionine moiety on the initiator tRNA in its recognition pocket on eIF2.
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Affiliation(s)
- Lee D Kapp
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 N. Wolfe Street 625 WBSB, Baltimore, MD 21205-2185, USA
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44
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Sakurai M, Ohtsuki T, Watanabe Y, Watanabe K. Requirement of modified residue m1A9 for EF-Tu binding to nematode mitochondrial tRNA lacking the T arm. Nucleic Acids Res Suppl 2003:237-8. [PMID: 12836352 DOI: 10.1093/nass/1.1.237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Most of nematode mitochondrial (mt) tRNAs lacking the T arm have 1-methyladenosine (m1A) at position 9. To investigate the effect of m1A, we constructed a nematode Ascaris suum mt tRNA(Met) containing only m1A9 as the modified nucleoside by means of molecular surgery. Although the unmodified A. suum mt Met-tRNA(Met) did not bind to nematode mt EF-Tu, the m1A9-containing tRNA bound to the EF-Tu, suggesting that m1A at position 9 is necessary for binding of nematode mt tRNAs lacking the T arm to the EF-Tu, probably because of maintenance of the L-shape-like structure or interaction with the C-terminal amino acid residues of the EF-Tu.
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Affiliation(s)
- M Sakurai
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo
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45
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Taki M, Sawata SY, Taira K. A novel immobilization method of an active protein via in vitro N-terminal specific incorporation system of nonnatural amino acids. Nucleic Acids Res Suppl 2003:197-8. [PMID: 12836332 DOI: 10.1093/nass/1.1.197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recently, we succeeded in incorporating a biotin tag into an active protein, but only at the N-terminal site, in the presence of an Escherichia coli initiator tRNA(fMet) aminoacylated with methionine biotinylated at the alpha-amino group. The biotinylated protein was immobilized on a streptavidin-matrix. We have tried to increase the biotin labeling efficiency (immobilization efficiency) by decreasing concentrations of non-biotinylated tRNA(fMet)s in the translation system.
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Affiliation(s)
- M Taki
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba Science City, 305-8562, Japan
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46
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Abstract
Eukaryotic aminoacyl-tRNA synthetases have dispensable extensions appended at the amino- or carboxyl-terminus as compared to their bacterial counterparts. While a synthetic peptide corresponding to the basic amino-terminal extension in yeast Asp-tRNA synthetase binds to DNA, the extension in the intact protein evidently binds to tRNA and enhances the tRNA specificity of Asp-tRNA synthetase. On the other hand, the amino-terminal extension in human Asp-tRNA synthetase, both within the intact protein and as a synthetic peptide, binds to tRNA. Here, the tRNA binding of a synthetic peptide, hKRS(Arg(25)-Glu(42)), corresponding to the amino-terminal extension of human Lys-tRNA synthetase (hKRS) was analyzed. This basic peptide bound to tRNA(Phe) and the apparent-binding constant increased with increasing concentrations of Mg(2+). The hKRS peptide also bound to DNA and polyphosphate; however, the apparent DNA-binding constants decreased at increasing concentrations of Mg(2+). The ability of the hKRS peptide to adopt alpha-helical conformation was demonstrated by NMR and circular dichroism. A Lys-rich peptide derived from the elongation factor 1alpha was also examined and bound to DNA but not to tRNA.
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MESH Headings
- Amino Acid Sequence
- Cations, Divalent/chemistry
- Circular Dichroism
- DNA/chemistry
- DNA/metabolism
- DNA-Binding Proteins/chemical synthesis
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/metabolism
- Humans
- Hydrogen-Ion Concentration
- Lysine-tRNA Ligase/chemistry
- Magnesium Chloride/chemistry
- Magnetic Resonance Spectroscopy
- Models, Molecular
- Molecular Sequence Data
- Molecular Weight
- Peptide Elongation Factor 1/chemistry
- Peptides/chemical synthesis
- Peptides/chemistry
- Peptides/metabolism
- Polyphosphates/chemistry
- Protein Binding
- Protein Structure, Secondary
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/metabolism
- RNA, Transfer, Phe/chemistry
- RNA, Transfer, Phe/metabolism
- RNA-Binding Proteins/chemical synthesis
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/metabolism
- Sodium Chloride/chemistry
- Spectrometry, Fluorescence
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Trifluoroethanol/chemistry
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47
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Mayer C, Stortchevoi A, Köhrer C, Varshney U, RajBhandary UL. Initiator tRNA and its role in initiation of protein synthesis. Cold Spring Harb Symp Quant Biol 2003; 66:195-206. [PMID: 12762022 DOI: 10.1101/sqb.2001.66.195] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- C Mayer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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48
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Abstract
By overexpression of modified Escherichia coli 23S rRNAs from multicopy plasmids, ribosomes were prepared that contained mutations in two regions (2447-2450 and 2457-2462) of 23S rRNA. Following mutagenesis and selection, two clones with mutations in the 2447-2450 region (peptidyltransferase center) and six with mutations in the 2457-2462 region (helix 89) were characterized. The mutations were shown to exhibit a high level of homology. Cell-free protein synthesizing systems prepared from these clones were found to exhibit significantly enhanced incorporation of d-methionine and d-phenylalanine into protein. The incorporations involved positions 10, 22, and 54 of E. coli dihydrofolate reductase and positions 247 and 250 of Photinus pyralis firefly luciferase. Interestingly, some of the derived proteins containing the d-amino acids (notably DHFR analogues altered at position 10) functioned as well as those containing the respective l-amino acids, while substitution at other positions resulted in proteins having greatly diminished activity.
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MESH Headings
- Amino Acids/chemistry
- Amino Acids/metabolism
- Cell-Free System
- Escherichia coli/enzymology
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Luciferases/chemistry
- Luciferases/genetics
- Luciferases/metabolism
- Mutation
- Protein Biosynthesis
- Proteins/chemical synthesis
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Met/chemistry
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
- Tetrahydrofolate Dehydrogenase/chemistry
- Tetrahydrofolate Dehydrogenase/genetics
- Tetrahydrofolate Dehydrogenase/metabolism
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Affiliation(s)
- Larisa M Dedkova
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, VA 22904, USA
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49
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Mayer C, Köhrer C, Kenny E, Prusko C, RajBhandary UL. Anticodon sequence mutants of Escherichia coli initiator tRNA: effects of overproduction of aminoacyl-tRNA synthetases, methionyl-tRNA formyltransferase, and initiation factor 2 on activity in initiation. Biochemistry 2003; 42:4787-99. [PMID: 12718519 DOI: 10.1021/bi034011r] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Anticodon sequence mutants of Escherichia coli initiator tRNA initiate protein synthesis with codons other than AUG and amino acids other than methionine. Because the anticodon sequence is, in many cases, important for recognition of tRNAs by aminoacyl-tRNA synthetases, the mutant tRNAs are aminoacylated in vivo with different amino acids. The activity of a mutant tRNA in initiation in vivo depends on (i) the level of expression of the tRNA, (ii) the extent of aminoacylation of the tRNA, (iii) the extent of formylation of the aminoacyl-tRNA to formylaminoacyl-tRNA (fAA-tRNA), and (iv) the affinity of the fAA-tRNA for the initiation factor IF2 and the ribosome. Previously, using E. coli overproducing aminoacyl-tRNA synthetases, methionyl-tRNA formyltransferase, or IF2, we identified the steps limiting the activity in initiation of mutant tRNAs aminoacylated with glutamine and valine. Here, we have identified the steps limiting the activity of mutant tRNAs aminoacylated with isoleucine and phenylalanine. The combined results of experiments involving a variety of initiation codons (AUG, UAG, CAG, GUC, AUC, and UUC) provide support to the hypothesis that the ribosome.fAA-tRNA complex can act as an intermediate in initiation of protein synthesis. Comparison of binding affinities of various fAA-tRNAs (fMet-, fGln-, fVal-, fIle-, and fPhe-tRNAs) to IF2 using surface plasmon resonance supports the idea that IF2 can act as a carrier of fAA-tRNA to the ribosome. Other results suggest that the C1xA72 base pair mismatch, unique to eubacterial and organellar initiator tRNAs, may also be important for the binding of fAA-tRNA to IF2.
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Affiliation(s)
- Christine Mayer
- Department of Biology, 68-671 Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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50
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Abstract
Trimethylamine N-oxide (TMAO) and urea are osmolytes. Osmolytes allow cells to remain viable in harsh or extreme environments. Both TMAO and urea are found in shark and rays at approximate molar ratios of 1:2, respectively. At this ratio TMAO nearly completely counteracts the destabilizing effects that urea has on proteins. We ask whether RNA, which is denatured by urea, is stabilized by TMAO in a manner similar to that seen for proteins. We found that TMAO stabilizes Escherichia coli tRNAfmet tertiary structure and counteracts the denaturing effects of urea at the same ratios found for proteins. Cation binding usually drives RNA tertiary structure formation. These results suggest that tertiary structure stability is not only sensitive to cations but also to the aqueous composition and properties of the solvent. We propose that tertiary structure folding is driven by unfavorable interactions between TMAO and the phosphodiester backbone.
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Affiliation(s)
- Thomas C Gluick
- Department of Chemistry and Biochemistry, P.O. Box 19065, The University of Texas at Arlington, Arlington, TX 76019, USA.
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