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Giegé R, Eriani G. The tRNA identity landscape for aminoacylation and beyond. Nucleic Acids Res 2023; 51:1528-1570. [PMID: 36744444 PMCID: PMC9976931 DOI: 10.1093/nar/gkad007] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 12/21/2022] [Accepted: 01/03/2023] [Indexed: 02/07/2023] Open
Abstract
tRNAs are key partners in ribosome-dependent protein synthesis. This process is highly dependent on the fidelity of tRNA aminoacylation by aminoacyl-tRNA synthetases and relies primarily on sets of identities within tRNA molecules composed of determinants and antideterminants preventing mischarging by non-cognate synthetases. Such identity sets were discovered in the tRNAs of a few model organisms, and their properties were generalized as universal identity rules. Since then, the panel of identity elements governing the accuracy of tRNA aminoacylation has expanded considerably, but the increasing number of reported functional idiosyncrasies has led to some confusion. In parallel, the description of other processes involving tRNAs, often well beyond aminoacylation, has progressed considerably, greatly expanding their interactome and uncovering multiple novel identities on the same tRNA molecule. This review highlights key findings on the mechanistics and evolution of tRNA and tRNA-like identities. In addition, new methods and their results for searching sets of multiple identities on a single tRNA are discussed. Taken together, this knowledge shows that a comprehensive understanding of the functional role of individual and collective nucleotide identity sets in tRNA molecules is needed for medical, biotechnological and other applications.
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Affiliation(s)
- Richard Giegé
- Correspondence may also be addressed to Richard Giegé.
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2
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Ganesh RB, Maerkl SJ. Biochemistry of Aminoacyl tRNA Synthetase and tRNAs and Their Engineering for Cell-Free and Synthetic Cell Applications. Front Bioeng Biotechnol 2022; 10:918659. [PMID: 35845409 PMCID: PMC9283866 DOI: 10.3389/fbioe.2022.918659] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Cell-free biology is increasingly utilized for engineering biological systems, incorporating novel functionality, and circumventing many of the complications associated with cells. The central dogma describes the information flow in biology consisting of transcription and translation steps to decode genetic information. Aminoacyl tRNA synthetases (AARSs) and tRNAs are key components involved in translation and thus protein synthesis. This review provides information on AARSs and tRNA biochemistry, their role in the translation process, summarizes progress in cell-free engineering of tRNAs and AARSs, and discusses prospects and challenges lying ahead in cell-free engineering.
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3
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Savino RJ, Kempisty B, Mozdziak P. The Potential of a Protein Model Synthesized Absent of Methionine. Molecules 2022; 27:3679. [PMID: 35744804 PMCID: PMC9230714 DOI: 10.3390/molecules27123679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/20/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022] Open
Abstract
Methionine is an amino acid long thought to be essential, but only in the case of protein synthesis initiation. In more recent years, methionine has been found to play an important role in antioxidant defense, stability, and modulation of cell and protein activity. Though these findings have expanded the previously held sentiment of methionine having a singular purpose within cells and proteins, the essential nature of methionine can still be challenged. Many of the features that give methionine its newfound functions are shared by the other sulfur-containing amino acid: cysteine. While the antioxidant, stabilizing, and cell/protein modulatory functions of cysteine have already been well established, recent findings have shown a similar hydrophobicity to methionine which suggests cysteine may be able to replace methionine in all functions outside of protein synthesis initiation with little effect on cell and protein function. Furthermore, a number of novel mechanisms for alternative initiation of protein synthesis have been identified that suggest a potential to bypass the traditional methionine-dependent initiation during times of stress. In this review, these findings are discussed with a number of examples that demonstrate a potential model for synthesizing a protein in the absence of methionine.
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Affiliation(s)
- Ronald J. Savino
- Prestige Department of Poultry Science, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27695, USA; (B.K.); (P.M.)
| | - Bartosz Kempisty
- Prestige Department of Poultry Science, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27695, USA; (B.K.); (P.M.)
- Department of Anatomy, Poznan University of Medical Sciences, 60-781 Poznan, Poland
- Department of Histology, Poznan University of Medical Sciences, 60-781 Poznan, Poland
- Department of Veterinary Surgery, Institute of Veterinary Sciences, Nicolaus Copernicus University, 87-100 Toruń, Poland
| | - Paul Mozdziak
- Prestige Department of Poultry Science, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27695, USA; (B.K.); (P.M.)
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4
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Tharp JM, Krahn N, Varshney U, Söll D. Hijacking Translation Initiation for Synthetic Biology. Chembiochem 2020; 21:1387-1396. [PMID: 32023356 PMCID: PMC7237318 DOI: 10.1002/cbic.202000017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Indexed: 12/17/2022]
Abstract
Genetic code expansion (GCE) has revolutionized the field of protein chemistry. Over the past several decades more than 150 different noncanonical amino acids (ncAAs) have been co-translationally installed into proteins within various host organisms. The vast majority of these ncAAs have been incorporated between the start and stop codons within an open reading frame. This requires that the ncAA be able to form a peptide bond at the α-amine, limiting the types of molecules that can be genetically encoded. In contrast, the α-amine of the initiating amino acid is not required for peptide bond formation. Therefore, including the initiator position in GCE allows for co-translational insertion of more diverse molecules that are modified, or completely lacking an α-amine. This review explores various methods which have been used to initiate protein synthesis with diverse molecules both in vitro and in vivo.
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Affiliation(s)
- Jeffery M Tharp
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Natalie Krahn
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012, India
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
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5
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Kawakami T, Ogawa K, Hatta T, Goshima N, Natsume T. Directed Evolution of a Cyclized Peptoid-Peptide Chimera against a Cell-Free Expressed Protein and Proteomic Profiling of the Interacting Proteins to Create a Protein-Protein Interaction Inhibitor. ACS Chem Biol 2016; 11:1569-77. [PMID: 27010125 DOI: 10.1021/acschembio.5b01014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-alkyl amino acids are useful building blocks for the in vitro display evolution of ribosomally synthesized peptides because they can increase the proteolytic stability and cell permeability of these peptides. However, the translation initiation substrate specificity of nonproteinogenic N-alkyl amino acids has not been investigated. In this study, we screened various N-alkyl amino acids and nonamino carboxylic acids for translation initiation with an Escherichia coli reconstituted cell-free translation system (PURE system) and identified those that efficiently initiated translation. Using seven of these efficiently initiating acids, we next performed in vitro display evolution of cyclized peptidomimetics against an arbitrarily chosen model human protein (β-catenin) cell-free expressed from its cloned cDNA (HUPEX) and identified a novel β-catenin-binding cyclized peptoid-peptide chimera. Furthermore, by a proteomic approach using direct nanoflow liquid chromatography-tandem mass spectrometry (DNLC-MS/MS), we successfully identified which protein-β-catenin interaction is inhibited by the chimera. The combination of in vitro display evolution of cyclized N-alkyl peptidomimetics and in vitro expression of human proteins would be a powerful approach for the high-speed discovery of diverse human protein-targeted cyclized N-alkyl peptidomimetics.
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Affiliation(s)
- Takashi Kawakami
- Molecular Profiling Research
Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Koji Ogawa
- Molecular Profiling Research
Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Tomohisa Hatta
- Molecular Profiling Research
Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Naoki Goshima
- Molecular Profiling Research
Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Tohru Natsume
- Molecular Profiling Research
Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
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6
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Ho JM, Reynolds NM, Rivera K, Connolly M, Guo LT, Ling J, Pappin DJ, Church GM, Söll D. Efficient Reassignment of a Frequent Serine Codon in Wild-Type Escherichia coli. ACS Synth Biol 2016; 5:163-71. [PMID: 26544153 DOI: 10.1021/acssynbio.5b00197] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Expansion of the genetic code through engineering the translation machinery has greatly increased the chemical repertoire of the proteome. This has been accomplished mainly by read-through of UAG or UGA stop codons by the noncanonical aminoacyl-tRNA of choice. While stop codon read-through involves competition with the translation release factors, sense codon reassignment entails competition with a large pool of endogenous tRNAs. We used an engineered pyrrolysyl-tRNA synthetase to incorporate 3-iodo-l-phenylalanine (3-I-Phe) at a number of different serine and leucine codons in wild-type Escherichia coli. Quantitative LC-MS/MS measurements of amino acid incorporation yields carried out in a selected reaction monitoring experiment revealed that the 3-I-Phe abundance at the Ser208AGU codon in superfolder GFP was 65 ± 17%. This method also allowed quantification of other amino acids (serine, 33 ± 17%; phenylalanine, 1 ± 1%; threonine, 1 ± 1%) that compete with 3-I-Phe at both the aminoacylation and decoding steps of translation for incorporation at the same codon position. Reassignments of different serine (AGU, AGC, UCG) and leucine (CUG) codons with the matching tRNA(Pyl) anticodon variants were met with varying success, and our findings provide a guideline for the choice of sense codons to be reassigned. Our results indicate that the 3-iodo-l-phenylalanyl-tRNA synthetase (IFRS)/tRNA(Pyl) pair can efficiently outcompete the cellular machinery to reassign select sense codons in wild-type E. coli.
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Affiliation(s)
- Joanne M. Ho
- Department
of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | | | - Keith Rivera
- Cold Spring Harbor Laboratory, Cold
Spring Harbor, New York 11724, United States
| | - Morgan Connolly
- Cold Spring Harbor Laboratory, Cold
Spring Harbor, New York 11724, United States
| | | | | | - Darryl J. Pappin
- Cold Spring Harbor Laboratory, Cold
Spring Harbor, New York 11724, United States
| | - George M. Church
- Department
of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
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7
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Rogers HH, Griffiths-Jones S. tRNA anticodon shifts in eukaryotic genomes. RNA (NEW YORK, N.Y.) 2014; 20:269-281. [PMID: 24442610 PMCID: PMC3923123 DOI: 10.1261/rna.041681.113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 11/30/2013] [Indexed: 06/03/2023]
Abstract
Embedded in the sequence of each transfer RNA are elements that promote specific interactions with its cognate aminoacyl tRNA-synthetase. Although many such "identity elements" are known, their detection is difficult since they rely on unique structural signatures and the combinatorial action of multiple elements spread throughout the tRNA molecule. Since the anticodon is often a major identity determinant itself, it is possible to switch between certain tRNA functional types by means of anticodon substitutions. This has been shown to have occurred during the evolution of some genomes; however, the scale and relevance of "anticodon shifts" to the evolution of the tRNA multigene family is unclear. Using a synteny-conservation-based method, we detected tRNA anticodon shifts in groups of closely related species: five primates, 12 Drosophila, six nematodes, 11 Saccharomycetes, and 61 Enterobacteriaceae. We found a total of 75 anticodon shifts: 31 involving switches of identity (alloacceptor shifts) and 44 between isoacceptors that code for the same amino acid (isoacceptor shifts). The relative numbers of shifts in each taxa suggest that tRNA gene redundancy is likely the driving factor, with greater constraint on changes of identity. Sites that frequently covary with alloacceptor shifts are located at the extreme ends of the molecule, in common with most known identity determinants. Isoacceptor shifts are associated with changes in the midsections of the tRNA sequence. However, the mutation patterns of anticodon shifts involving the same identities are often dissimilar, suggesting that alternate sets of mutation may achieve the same functional compensation.
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8
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Arora S, Bhamidimarri SP, Bhattacharyya M, Govindan A, Weber MHW, Vishveshwara S, Varshney U. Distinctive contributions of the ribosomal P-site elements m2G966, m5C967 and the C-terminal tail of the S9 protein in the fidelity of initiation of translation in Escherichia coli. Nucleic Acids Res 2013; 41:4963-75. [PMID: 23530111 PMCID: PMC3643588 DOI: 10.1093/nar/gkt175] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The accuracy of pairing of the anticodon of the initiator tRNA (tRNAfMet) and the initiation codon of an mRNA, in the ribosomal P-site, is crucial for determining the translational reading frame. However, a direct role of any ribosomal element(s) in scrutinizing this pairing is unknown. The P-site elements, m2G966 (methylated by RsmD), m5C967 (methylated by RsmB) and the C-terminal tail of the protein S9 lie in the vicinity of tRNAfMet. We investigated the role of these elements in initiation from various codons, namely, AUG, GUG, UUG, CUG, AUA, AUU, AUC and ACG with tRNA (tRNAfMet with CAU anticodon); CAC and CAU with tRNA; UAG with tRNA; UAC with tRNA; and AUC with tRNA using in vivo and computational methods. Although RsmB deficiency did not impact initiation from most codons, RsmD deficiency increased initiation from AUA, CAC and CAU (2- to 3.6-fold). Deletion of the S9 C-terminal tail resulted in poorer initiation from UUG, GUG and CUG, but in increased initiation from CAC, CAU and UAC codons (up to 4-fold). Also, the S9 tail suppressed initiation with tRNA lacking the 3GC base pairs in the anticodon stem. These observations suggest distinctive roles of 966/967 methylations and the S9 tail in initiation.
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Affiliation(s)
- Smriti Arora
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
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9
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Sherman JM, Rogers MJ, Söll D. Competition of aminoacyl-tRNA synthetases for tRNA ensures the accuracy of aminoacylation. Nucleic Acids Res 2010; 20:1547-52. [PMID: 16617497 PMCID: PMC312236 DOI: 10.1093/nar/20.7.1547] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The accuracy of protein biosynthesis rests on the high fidelity with which aminoacyl-tRNA synthetases discriminate between tRNAs. Correct aminoacylation depends not only on identity elements (nucleotides in certain positions) in tRNA (1), but also on competition between different synthetases for a given tRNA (2). Here we describe in vivo and in vitro experiments which demonstrate how variations in the levels of synthetases and tRNA affect the accuracy of aminoacylation. We show in vivo that concurrent overexpression of Escherichia coli tyrosyl-tRNA synthetase abolishes misacylation of supF tRNA(Tyr) with glutamine in vivo by overproduced glutaminyl-tRNA synthetase. In an in vitro competition assay, we have confirmed that the overproduction mischarging phenomenon observed in vivo is due to competition between the synthetases at the level of aminoacylation. Likewise, we have been able to examine the role competition plays in the identity of a non-suppressor tRNA of ambiguous identity, tRNA(Glu). Finally, with this assay, we show that the identity of a tRNA and the accuracy with which it is recognized depend on the relative affinities of the synthetases for the tRNA. The in vitro competition assay represents a general method of obtaining qualitative information on tRNA identity in a competitive environment (usually only found in vivo) during a defined step in protein biosynthesis, aminoacylation. In addition, we show that the discriminator base (position 73) and the first base of the anticodon are important for recognition by E. coli tyrosyl-tRNA synthetase.
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Affiliation(s)
- J M Sherman
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
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10
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Carullo M, Xia X. An extensive study of mutation and selection on the wobble nucleotide in tRNA anticodons in fungal mitochondrial genomes. J Mol Evol 2008; 66:484-93. [PMID: 18401633 DOI: 10.1007/s00239-008-9102-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 03/05/2008] [Accepted: 03/19/2008] [Indexed: 10/22/2022]
Abstract
Two alternative hypotheses aim to predict the wobble nucleotide of tRNA anticodons in mitochondrion. The codon-anticodon adaptation hypothesis predicts that the wobble nucleotide of tRNA anticodon should evolve toward maximizing the Watson-Crick base pairing with the most frequently used codon within each synonymous codon family. In contrast, the wobble versatility hypothesis argues that the nucleotide at the wobble site should be occupied by a nucleotide most versatile in wobble pairing, i.e., the wobble site of the tRNA anticodon should be G for NNY codon families and U for NNR and NNN codon families (where Y stands for C or U, R for A or G, and N for any nucleotide). We examined codon usage and anticodon wobble sites in 36 fungal genomes to evaluate these two alternative hypotheses and identify exceptional cases that deserve new explanations. While the wobble versatility hypothesis is generally supported, there are interesting exceptions involving tRNA(Arg) translating the CGN codon family, tRNA(Trp) translating the UGR codon family, and tRNA(Met) translating the AUR codon family. Our results suggest that the potential to suppress stop codons, the historical inertia, and the conflict between translation initiation and elongation can all contribute to determining the wobble nucleotide of tRNA anticodons.
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Affiliation(s)
- Malisa Carullo
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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11
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Jones TE, Brown CL, Geslain R, Alexander RW, Ribas de Pouplana L. An operational RNA code for faithful assignment of AUG triplets to methionine. Mol Cell 2008; 29:401-7. [PMID: 18280245 DOI: 10.1016/j.molcel.2007.12.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/26/2007] [Accepted: 12/03/2007] [Indexed: 12/01/2022]
Abstract
The assignment of AUG codons to methionine remains a central question of the evolution of the genetic code. We have unveiled a strategy for the discrimination among tRNAs containing CAU (AUG-decoding) anticodons. Mycoplasma penetrans methionyl-tRNA synthetase can directly differentiate between tRNA(Ile)(CAU) and tRNA(Met)(CAU) transcripts (a recognition normally achieved through the modification of anticodon bases). This discrimination mechanism is based only on interactions with the acceptor stems of tRNA(Ile)(CAU) and tRNA(Met)(CAU). Thus, in certain species, the fidelity of translation of methionine codons requires a discrimination mechanism that is independent of the information contained in the anticodon.
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Affiliation(s)
- Thomas E Jones
- Barcelona Institute for Research in Biomedicine, Barcelona Science Park, C/Samitier 1-5, Barcelona 08015, Catalonia, Spain
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12
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Das G, Dineshkumar TK, Thanedar S, Varshney U. Acquisition of a stable mutation in metY allows efficient initiation from an amber codon in Escherichia coli. Microbiology (Reading) 2005; 151:1741-1750. [PMID: 15941983 DOI: 10.1099/mic.0.27915-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Escherichia colistrains harbouring elongator tRNAs that insert amino acids in response to a termination codon during elongation have been generated for various applications. Additionally, it was shown that expression of an initiator tRNA containing a CUA anticodon from a multicopy plasmid inE. coliresulted in initiation from an amber codon. Even though the initiation-based system remedies toxicity-related drawbacks, its usefulness has remained limited for want of a strain with a chromosomally encoded initiator tRNA ‘suppressor’.E. coliK strains possess four initiator tRNA genes: themetZ,metWandmetVgenes, located at a single locus, encode tRNA1fMet, and a distantly locatedmetYgene encodes a variant, tRNA2fMet. In this study, a stable strain ofE. coliK-12 that affords efficient initiation from an amber initiation codon was isolated. Genetic analysis revealed that themetYgene in this strain acquired mutations to encode tRNA2fMetwith a CUA anticodon (a U35A36 mutation). The acquisition of the mutations depended on the presence of a plasmid-borne copy of the mutantmetYandrecA+host background. The mutations were observed when the plasmid-borne gene encoded tRNA2fMet(U35A36) with additional changes in the acceptor stem (G72; G72G73) but not in the anticodon stem (U29C30A31/U35A36/ψ39G40A41). The usefulness of this strain, and a possible role for multiple tRNA1fMetgenes inE. coliin safeguarding their intactness, are discussed.
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Affiliation(s)
- Gautam Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - T K Dineshkumar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Swapna Thanedar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
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13
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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 HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 66:195-206. [PMID: 12762022 DOI: 10.1101/sqb.2001.66.195] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [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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14
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Fukai S, Nureki O, Sekine SI, Shimada A, Vassylyev DG, Yokoyama S. Mechanism of molecular interactions for tRNA(Val) recognition by valyl-tRNA synthetase. RNA (NEW YORK, N.Y.) 2003; 9:100-111. [PMID: 12554880 PMCID: PMC1370374 DOI: 10.1261/rna.2760703] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2002] [Accepted: 09/23/2002] [Indexed: 05/24/2023]
Abstract
The molecular interactions between valyl-tRNA synthetase (ValRS) and tRNA(Val), with the C34-A35-C36 anticodon, from Thermus thermophilus were studied by crystallographic analysis and structure-based mutagenesis. In the ValRS-bound structure of tRNA(Val), the successive A35-C36 residues (the major identity elements) of tRNA(Val) are base-stacked upon each other, and fit into a pocket on the alpha-helix bundle domain of ValRS. Hydrogen bonds are formed between ValRS and A35-C36 of tRNA(Val) in a base-specific manner. The C-terminal coiled-coil domain of ValRS interacts electrostatically with A20 and hydrophobically with the G19*C56 tertiary base pair. The loss of these interactions by the deletion of the coiled-coil domain of ValRS increased the K(M) value for tRNA(Val) 28-fold and decreased the k(cat) value 19-fold in the aminoacylation. The tRNA(Val) K(M) and k(cat) values were increased 21-fold and decreased 32-fold, respectively, by the disruption of the G18*U55 and G19*C56 tertiary base pairs, which associate the D- and T-loops for the formation of the L-shaped tRNA structure. Therefore, the coiled-coil domain of ValRS is likely to stabilize the L-shaped tRNA structure during the aminoacylation reaction.
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Affiliation(s)
- Shuya Fukai
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Japan
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15
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Tardif KD, Horowitz J. Transfer RNA determinants for translational editing by Escherichia coli valyl-tRNA synthetase. Nucleic Acids Res 2002; 30:2538-45. [PMID: 12034843 PMCID: PMC117182 DOI: 10.1093/nar/30.11.2538] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Valyl-tRNA synthetase (ValRS) has difficulty differentiating valine from structurally similar non-cognate amino acids, most prominently threonine. To minimize errors in aminoacylation and translation the enzyme catalyzes a proofreading (editing) reaction that is dependent on the presence of cognate tRNA(Val). Editing occurs at a site functionally distinct from the aminoacylation site of ValRS and previous results have shown that the 3'-terminus of tRNA(Val) is recognized differently at the two sites. Here, we extend these studies by comparing the contribution of aminoacylation identity determinants to productive recognition of tRNA(Val) at the aminoacylation and editing sites, and by probing tRNA(Val) for editing determinants that are distinct from those required for aminoacylation. Mutational analysis of Escherichia coli tRNA(Val) and identity switch experiments with non-cognate tRNAs reveal a direct relationship between the ability of a tRNA to be aminoacylated and its ability to stimulate the editing activity of ValRS. This suggests that at least a majority of editing by the enzyme entails prior charging of tRNA and that misacylated tRNA is a transient intermediate in the editing reaction.
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Affiliation(s)
- Keith D Tardif
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
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16
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Abstract
The aminoacyl-tRNA synthetases are an ancient group of enzymes that catalyze the covalent attachment of an amino acid to its cognate transfer RNA. The question of specificity, that is, how each synthetase selects the correct individual or isoacceptor set of tRNAs for each amino acid, has been referred to as the second genetic code. A wealth of structural, biochemical, and genetic data on this subject has accumulated over the past 40 years. Although there are now crystal structures of sixteen of the twenty synthetases from various species, there are only a few high resolution structures of synthetases complexed with cognate tRNAs. Here we review briefly the structural information available for synthetases, and focus on the structural features of tRNA that may be used for recognition. Finally, we explore in detail the insights into specific recognition gained from classical and atomic group mutagenesis experiments performed with tRNAs, tRNA fragments, and small RNAs mimicking portions of tRNAs.
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Affiliation(s)
- P J Beuning
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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17
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Kim HS, Kim IY, Söll D, Lee SY. Transfer RNA identity change in anticodon variants of E. coli tRNA(Phe) in vivo. Mol Cells 2000; 10:76-82. [PMID: 10774751 DOI: 10.1007/s10059-000-0076-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The anticodon sequence is a major recognition element for most aminoacyl-tRNA synthetases. We investigated the in vivo effects of changing the anticodon on the aminoacylation specificity in the example of E. coli tRNA(Phe). Constructing different anticodon mutants of E. coli tRNA(Phe) by site-directed mutagenesis, we isolated 22 anticodon mutant tRNA(Phe); the anticodons corresponded to 16 amino acids and an opal stop codon. To examine whether the mutant tRNAs had changed their amino acid acceptor specificity in vivo, we tested the viability of E. coli strains containing these tRNA(Phe) genes in a medium which permitted tRNA induction. Fourteen mutant tRNA genes did not affect host viability. However, eight mutant tRNA genes were toxic to the host and prevented growth, presumably because the anticodon mutants led to translational errors. Many mutant tRNAs which did not affect host viability were not aminoacylated in vivo. Three mutant tRNAs containing anticodon sequences corresponding to lysine (UUU), methionine (CAU) and threonine (UGU) were charged with the amino acid corresponding to their anticodon, but not with phenylalanine. These three tRNAs and tRNA(Phe) are located in the same cluster in a sequence similarity dendrogram of total E. coli tRNAs. The results support the idea that such tRNAs arising from in vivo evolution are derived by anticodon change from the same ancestor tRNA.
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Affiliation(s)
- H S Kim
- Graduate School of Biotechnology, Korea University, Seoul
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18
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Giegé R, Sissler M, Florentz C. Universal rules and idiosyncratic features in tRNA identity. Nucleic Acids Res 1998; 26:5017-35. [PMID: 9801296 PMCID: PMC147952 DOI: 10.1093/nar/26.22.5017] [Citation(s) in RCA: 611] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Correct expression of the genetic code at translation is directly correlated with tRNA identity. This survey describes the molecular signals in tRNAs that trigger specific aminoacylations. For most tRNAs, determinants are located at the two distal extremities: the anticodon loop and the amino acid accepting stem. In a few tRNAs, however, major identity signals are found in the core of the molecule. Identity elements have different strengths, often depend more on k cat effects than on K m effects and exhibit additive, cooperative or anti-cooperative interplay. Most determinants are in direct contact with cognate synthetases, and chemical groups on bases or ribose moieties that make functional interactions have been identified in several systems. Major determinants are conserved in evolution; however, the mechanisms by which they are expressed are species dependent. Recent studies show that alternate identity sets can be recognized by a single synthetase, and emphasize the importance of tRNA architecture and anti-determinants preventing false recognition. Identity rules apply to tRNA-like molecules and to minimalist tRNAs. Knowledge of these rules allows the manipulation of identity elements and engineering of tRNAs with switched, altered or multiple specificities.
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MESH Headings
- Amino Acyl-tRNA Synthetases/metabolism
- Evolution, Molecular
- Genetic Code
- Humans
- Kinetics
- Models, Molecular
- Nucleic Acid Conformation
- Protein Biosynthesis
- RNA, Transfer/chemistry
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Amino Acyl/metabolism
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Affiliation(s)
- R Giegé
- Unité Propre de Recherche 9002, 'Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance', Scientifique, 15 rue René Descartes, F-67084, Strasbourg Cedex, France.
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19
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Drabkin HJ, RajBhandary UL. Initiation of protein synthesis in mammalian cells with codons other than AUG and amino acids other than methionine. Mol Cell Biol 1998; 18:5140-7. [PMID: 9710598 PMCID: PMC109099 DOI: 10.1128/mcb.18.9.5140] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/1998] [Accepted: 06/12/1998] [Indexed: 11/20/2022] Open
Abstract
Protein synthesis is initiated universally with the amino acid methionine. In Escherichia coli, studies with anticodon sequence mutants of the initiator methionine tRNA have shown that protein synthesis can be initiated with several other amino acids. In eukaryotic systems, however, a yeast initiator tRNA aminoacylated with isoleucine was found to be inactive in initiation in mammalian cell extracts. This finding raised the question of whether methionine is the only amino acid capable of initiation of protein synthesis in eukaryotes. In this work, we studied the activities, in initiation, of four different anticodon sequence mutants of human initiator tRNA in mammalian COS1 cells, using reporter genes carrying mutations in the initiation codon that are complementary to the tRNA anticodons. The mutant tRNAs used are aminoacylated with glutamine, methionine, and valine. Our results show that in the presence of the corresponding mutant initiator tRNAs, AGG and GUC can initiate protein synthesis in COS1 cells with methionine and valine, respectively. CAG initiates protein synthesis with glutamine but extremely poorly, whereas UAG could not be used to initiate protein synthesis with glutamine. We discuss the potential applications of the mutant initiator tRNA-dependent initiation of protein synthesis with codons other than AUG for studying the many interesting aspects of protein synthesis initiation in mammalian cells.
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Affiliation(s)
- H J Drabkin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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20
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Saks ME, Sampson JR, Abelson J. Evolution of a transfer RNA gene through a point mutation in the anticodon. Science 1998; 279:1665-70. [PMID: 9497276 DOI: 10.1126/science.279.5357.1665] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The transfer RNA (tRNA) multigene family comprises 20 amino acid-accepting groups, many of which contain isoacceptors. The addition of isoacceptors to the tRNA repertoire was critical to establishing the genetic code, yet the origin of isoacceptors remains largely unexplored. A model of tRNA evolution, termed "tRNA gene recruitment," was formulated. It proposes that a tRNA gene can be recruited from one isoaccepting group to another by a point mutation that concurrently changes tRNA amino acid identity and messenger RNA coupling capacity. A test of the model showed that an Escherichia coli strain, in which the essential tRNAUGUThr gene was inactivated, was rendered viable when a tRNAArg with a point mutation that changed its anticodon from UCU to UGU (threonine) was expressed. Insertion of threonine at threonine codons by the "recruited" tRNAArg was corroborated by in vitro aminoacylation assays showing that its specificity had been changed from arginine to threonine. Therefore, the recruitment model may account for the evolution of some tRNA genes.
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MESH Headings
- Anticodon/genetics
- Arginine/metabolism
- Base Composition
- Base Sequence
- Escherichia coli/genetics
- Evolution, Molecular
- Genes, Bacterial
- Haemophilus influenzae/genetics
- Models, Genetic
- Molecular Sequence Data
- Multigene Family
- Nucleic Acid Conformation
- Point Mutation
- Polymerase Chain Reaction
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer, Arg/chemistry
- RNA, Transfer, Arg/genetics
- RNA, Transfer, Arg/metabolism
- RNA, Transfer, Thr/chemistry
- RNA, Transfer, Thr/genetics
- RNA, Transfer, Thr/metabolism
- Recombination, Genetic
- Temperature
- Threonine/metabolism
- Transformation, Bacterial
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Affiliation(s)
- M E Saks
- Division of Biology 147-75, California Institute of Technology, Pasadena, CA 91125, USA.
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21
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Wu XQ, RajBhandary UL. Effect of the amino acid attached to Escherichia coli initiator tRNA on its affinity for the initiation factor IF2 and on the IF2 dependence of its binding to the ribosome. J Biol Chem 1997; 272:1891-5. [PMID: 8999877 DOI: 10.1074/jbc.272.3.1891] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We show that the nature of the amino acid in the formylaminoacyl-tRNA influences initiation factor (IF) 2 dependence of its ribosome binding and that this IF2 dependence reflects the relative affinity of the formylaminoacyl-tRNA for the initiation factor IF2. We compared the template-dependent ribosome binding activities, in the presence of initiation factors, of wild type and anticodon sequence mutants of Escherichia coli initiator tRNAs that carry formylmethionine (fMet), formylglutamine (fGln), or formylvaline (fVal). The fGln-tRNA bound less well than fMet-tRNA whereas the fVal-tRNA bound as well as fMet-tRNA. The rate and extent of binding of fGln-tRNA to the ribosome was significantly increased by further addition of purified initiation factor IF2. In contrast, the binding of fVal-tRNA or fMet-tRNA was not affected much by the addition of IF2. Using gel mobility shift assay, we have measured the apparent Kd values of the IF2.formylaminoacyl-tRNA binary complexes. These are 1.8, 3.5, and 10.5 microM for fMet-tRNA, fVal-tRNA, and fGln-tRNA, respectively.
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Affiliation(s)
- X Q Wu
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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22
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Wu XQ, Iyengar P, RajBhandary UL. Ribosome-initiator tRNA complex as an intermediate in translation initiation in Escherichia coli revealed by use of mutant initiator tRNAs and specialized ribosomes. EMBO J 1996; 15:4734-9. [PMID: 8887564 PMCID: PMC452205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
For functional studies of mutant Escherichia coli initiator tRNAs in vivo, we previously described a strategy based on the use of tRNA genes carrying an anticodon sequence change from CAU to CUA along with a mutant chloramphenicol acetyltransferase (CAT) gene carrying an initiation codon change from AUG to UAG. Surprisingly, under conditions where the mutant initiator tRNA is optimally active, the CAT gene with the UAG initiation codon produced more CAT protein (3- to 9-fold more depending on the conditions) than the wild-type CAT gene. Here we show that two new mutant CAT genes having GUC and AUC initiation codons also produce more of the CAT protein in the presence of the corresponding mutant initiator tRNAs. These results are most easily understood if assembly of the 30S ribosome-initiator tRNA-mRNA initiation complex in vivo proceeds with the 30S ribosome binding first to the initiator tRNA and then to the mRNA. In cells overproducing the mutant initiator tRNAs, most ribosomes would carry the mutant initiator tRNA and these ribosomes would select the mutant CAT mRNA over the other mRNAs.
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Affiliation(s)
- X Q Wu
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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23
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Li S, Kumar NV, Varshney U, RajBhandary UL. Important role of the amino acid attached to tRNA in formylation and in initiation of protein synthesis in Escherichia coli. J Biol Chem 1996; 271:1022-8. [PMID: 8557626 DOI: 10.1074/jbc.271.2.1022] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In attempts to convert an elongator tRNA to an initiator tRNA, we previously generated a mutant elongator methionine tRNA carrying an anticodon sequence change from CAU to CUA along with the two features important for activity of Escherichia coli initiator tRNA in initiation. This mutant tRNA (Mi:2 tRNA) was active in initiation in vivo but only when aminoacylated with methionine by overproduction of methionyl-tRNA synthetase. Here we show that the Mi:2 tRNA is normally aminoacylated in vivo with lysine and that the tRNA aminoacylated with lysine is a very poor substrate for formylation compared with the same tRNA aminoacylated with methionine. By introducing further changes at base pairs 4:69 and 5:68 in the acceptor stem of the Mi:2 tRNA to those found in the E. coli initiator tRNA, we show that change of the U4:A69 base pair to G4:C69 and overproduction of lysyl-tRNA synthetase and methionyl-tRNA transformylase results in partial formylation of the mutant tRNA and activity of the formyllysyl-tRNAs in initiation of protein synthesis. Thus, the G4: C69 base pair contributes toward formylation of the tRNA and protein synthesis in E. coli can be initiated with formyllysine. We also discuss the implications of these and other results on recognition of tRNAs by E. coli lysyl-tRNA synthetase and on competition in cells among aminoacyl-tRNA synthetases.
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Affiliation(s)
- S Li
- Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA
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24
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Schmitt E, Guillon JM, Meinnel T, Mechulam Y, Dardel F, Blanquet S. Molecular recognition governing the initiation of translation in Escherichia coli. A review. Biochimie 1996; 78:543-54. [PMID: 8955898 DOI: 10.1016/s0300-9084(96)80001-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Selection of the proper start codon for the synthesis of a polypeptide by the Escherichia coli translation initiation apparatus involves several macromolecular components. These macromolecules interact in a specific and concerted manner to yield the translation initiation complex. This review focuses on recent data concerning the properties of the initiator tRNA and of enzymes and factors involved in the translation initiation process. The three initiation factors, as well as methionyl-tRNA synthetase and methionyl-tRNA(f)Met formyltransferase are described. In addition, the tRNA recognition properties of EF-Tu and peptidyl-tRNA hydrolase are considered. Finally, peptide deformylase and methionine aminopeptidase, which catalyze the amino terminal maturation of nascent polypeptides, can also be associated to the translation initiation process.
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Affiliation(s)
- E Schmitt
- Laboratoire de Biochimie, URA-CNRS no 1970, Ecole Polytechnique, Palaiseau, France
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25
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Abstract
The aminoacylation of tRNAs by the aminoacyl-tRNA synthetases recapitulates the genetic code by dictating the association between amino acids and tRNA anticodons. The sequences of tRNAs were analyzed to investigate the nature of primordial recognition systems and to make inferences about the evolution of tRNA gene sequences and the evolution of the genetic code. Evidence is presented that primordial synthetases recognized acceptor stem nucleotides prior to the establishment of the three major phylogenetic lineages. However, acceptor stem sequences probably did not achieve a level of sequence diversity sufficient to faithfully specify the anticodon assignments of all 20 amino acids. This putative bottleneck in the evolution of the genetic code may have been alleviated by the advent of anticodon recognition. A phylogenetic analysis of tRNA gene sequences from the deep Archaea revealed groups that are united by sequence motifs which are located within a region of the tRNA that is involved in determining its tertiary structure. An association between the third anticodon nucleotide (N36) and these sequence motifs suggests that a tRNA-like structure existed close to the time that amino acid-anticodon assignments were being established. The sequence analysis also revealed that tRNA genes may evolve by anticodon mutations that recruit tRNAs from one isoaccepting group to another. Thus tRNA gene evolution may not always be monophyletic with respect to each isoaccepting group.
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Affiliation(s)
- M E Saks
- Division of Biology 147-75, California Institute of Technology, Pasadena 91125, USA
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26
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Mechulam Y, Meinnel T, Blanquet S. A family of RNA-binding enzymes. the aminoacyl-tRNA synthetases. Subcell Biochem 1995; 24:323-376. [PMID: 7900181 DOI: 10.1007/978-1-4899-1727-0_11] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- Y Mechulam
- Laboratoire de Biochimie, CNRS n. 240, Ecole Polytechnique, Palaiseau, France
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27
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Carneiro VT, Dietrich A, Maréchal-Drouard L, Cosset A, Pelletier G, Small I. Characterization of some major identity elements in plant alanine and phenylalanine transfer RNAs. PLANT MOLECULAR BIOLOGY 1994; 26:1843-53. [PMID: 7532029 DOI: 10.1007/bf00019497] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Alanine and phenylalanine tRNA sequences were amplified by PCR from Arabidopsis thaliana nuclear DNA using degenerate oligonucleotides which introduced specific mutations into the acceptor stem. The aminoacylation of T7 RNA polymerase transcripts of these sequences was investigated in vitro using partially purified bean alanyl- or phenylalanyl-tRNA synthetase. In parallel, the in vivo activity of amber suppressor derivatives of these tRNAs was investigated in transient expression assays in tobacco protoplasts using a beta-glucuronidase (GUS) reporter gene containing a premature amber stop codon. The results show that mutation of the G3:U70 base pair to G3:C70 blocks aminoacylation of plant alanine tRNA, whilst conversion of the G3:C70 pair normally found in plant tRNA(Phe) to G3:U70 enables the mutated tRNA(Phe) to be a good substrate for alanyl-tRNA synthetase and impairs its aminoacylation with phenylalanine. In addition, the amber suppressor derivative of wild-type tRNA(Phe) showed very little suppressor activity in vivo, and was poorly aminoacylated with phenylalanine in vitro, suggesting that the anticodon is a major identity determinant for tRNA(Phe) in plant cells.
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MESH Headings
- Alanine-tRNA Ligase/metabolism
- Anticodon
- Arabidopsis/genetics
- Base Composition
- Base Sequence
- Brassica/genetics
- Cloning, Molecular
- Genes, Reporter
- Glucuronidase/biosynthesis
- Glucuronidase/genetics
- Molecular Sequence Data
- Phenylalanine-tRNA Ligase/metabolism
- Plants/genetics
- Plants, Toxic
- Polymerase Chain Reaction
- Protoplasts
- RNA/biosynthesis
- RNA, Transfer, Ala/genetics
- RNA, Transfer, Ala/metabolism
- RNA, Transfer, Phe/genetics
- RNA, Transfer, Phe/metabolism
- Sequence Analysis, DNA
- Solanum tuberosum/genetics
- Substrate Specificity
- Suppression, Genetic
- Nicotiana/genetics
- Transcription, Genetic
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Affiliation(s)
- V T Carneiro
- Station de Génétique et d'Amélioration des Plantes, INRA, Centre de Versailles, France
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28
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Niimi T, Nureki O, Yokogawa T, Hayashi N, Nishikawa K, Watanabe K, Yokoyama S. Recognition of the Anticodon Loop of tRNAIle1by Isoleucyl-tRNA Synthetase fromEscherichia coli. ACTA ACUST UNITED AC 1994. [DOI: 10.1080/15257779408012147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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29
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Abstract
Correct recognition of transfer RNAs (tRNAs) by aminoacyl-tRNA synthetases is central to the maintenance of translational fidelity. The hypothesis that synthetases recognize anticodon nucleotides was proposed in 1964 and had considerable experimental support by the mid-1970s. Nevertheless, the idea was not widely accepted until relatively recently in part because the methodologies initially available for examining tRNA recognition proved hampering for adequately testing alternative hypotheses. Implementation of new technologies has led to a reasonably complete picture of how tRNAs are recognized. The anticodon is indeed important for 17 of the 20 Escherichia coli isoaccepting groups. For many of the isoaccepting groups, the acceptor stem or position 73 (or both) is important as well.
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Affiliation(s)
- M E Saks
- Division of Biology, California Institute of Technology, Pasadena 91125
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30
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Pak M, Willis I, Schulman L. Analysis of acceptor stem base pairing on tRNA(Trp) aminoacylation and function in vivo. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42165-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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31
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Frugier M, Florentz C, Schimmel P, Giegé R. Triple aminoacylation specificity of a chimerized transfer RNA. Biochemistry 1993; 32:14053-61. [PMID: 8268184 DOI: 10.1021/bi00213a039] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We report here the rational design and construction of a chimerized transfer RNA with tripartite aminoacylation specificity. A yeast aspartic acid specific tRNA was transformed into a highly efficient acceptor of alanine and phenylalanine and a moderate acceptor of valine. The transformation was guided by available knowledge of the requirements for aminoacylation by each of the three amino acids and was achieved by iterative changes in the local sequence context and the structural framework of the variable loop and the two variable regions of the dihydrouridine loop. The changes introduced to confer efficient acceptance of the three amino acids eliminate aminoacylation with aspartate. The interplay of determinants and antideterminants for different specific aminoacylations, and the constraints imposed by the structural framework, suggest that a tRNA with an appreciable capacity for more than three efficient aminoacylations may be inherently difficult to achieve.
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Affiliation(s)
- M Frugier
- Unité Propre de Recherche Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, Centre National de la Recherche Scientifique, Strasbourg, France
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32
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Schimmel P, Giegé R, Moras D, Yokoyama S. An operational RNA code for amino acids and possible relationship to genetic code. Proc Natl Acad Sci U S A 1993; 90:8763-8. [PMID: 7692438 PMCID: PMC47440 DOI: 10.1073/pnas.90.19.8763] [Citation(s) in RCA: 308] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
RNA helical oligonucleotides that recapitulate the acceptor stems of transfer RNAs, and that are devoid of the anticodon trinucleotides of the genetic code, are aminoacylated by aminoacyl tRNA synthetases. The specificity of aminoacylation is sequence dependent, and both specificity and efficiency are generally determined by only a few nucleotides proximal to the amino acid attachment site. This sequence/structure-dependent aminoacylation of RNA oligonucleotides constitutes an operational RNA code for amino acids. To a rough approximation, members of the two different classes of tRNA synthetases are, like tRNAs, organized into two major domains. The class-defining conserved domain containing the active site incorporates determinants for recognition of RNA mini-helix substrates. This domain may reflect the primordial synthetase, which was needed for expression of the operational RNA code. The second synthetase domain, which generally is less or not conserved, provides for interactions with the second domain of tRNA, which incorporates the anticodon. The emergence of the genetic from the operational RNA code could occur when the second domain of synthetases was added with the anticodon-containing domain of tRNAs.
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Affiliation(s)
- P Schimmel
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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33
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Martinis S, Schimmel P. Microhelix aminoacylation by a class I tRNA synthetase. Non-conserved base pairs required for specificity. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53219-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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34
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Yesland K, Nelson A, Six Feathers D, Johnson J. Identity of Saccharomyces cerevisiae tRNA(Trp) is not changed by an anticodon mutation that creates an amber suppressor. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)54137-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Giegé R, Puglisi JD, Florentz C. tRNA structure and aminoacylation efficiency. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1993; 45:129-206. [PMID: 8341800 DOI: 10.1016/s0079-6603(08)60869-7] [Citation(s) in RCA: 180] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- R Giegé
- Unité Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, Institut de Biologie Moléculaire et Cellulaire du Centre National de la Recherche Scientifique, Strasbourg, France
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36
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Varshney U, RajBhandary UL. Role of methionine and formylation of initiator tRNA in initiation of protein synthesis in Escherichia coli. J Bacteriol 1992; 174:7819-26. [PMID: 1447148 PMCID: PMC207498 DOI: 10.1128/jb.174.23.7819-7826.1992] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We showed recently that a mutant of Escherichia coli initiator tRNA with a CAU-->CUA anticodon sequence change can initiate protein synthesis from UAG by using formylglutamine instead of formylmethionine. We further showed that coupling of the anticodon sequence change to mutations in the acceptor stem that reduced Vmax/Km(app) in formylation of the tRNAs in vitro significantly reduced their activity in initiation in vivo. In this work, we have screened an E. coli genomic DNA library in a multicopy vector carrying one of the mutant tRNA genes and have found that the gene for E. coli methionyl-tRNA synthetase (MetRS) rescues, partially, the initiation defect of the mutant tRNA. For other mutant tRNAs, we have examined the effect of overproduction of MetRS on their activities in initiation and their aminoacylation and formylation in vivo. Some but not all of the tRNA mutants can be rescued. Those that cannot be rescued are extremely poor substrates for MetRS or the formylating enzyme. Overproduction of MetRS also significantly increases the initiation activity of a tRNA mutant which can otherwise be aminoacylated with glutamine and fully formylated in vivo. We interpret these results as follows. (i) Mutant initiator tRNAs that are poor substrates for MetRS are aminoacylated in part with methionine when MetRS is overproduced. (ii) Mutant tRNAs aminoacylated with methionine are better substrates for the formylating enzyme in vivo than mutant tRNAs aminoacylated with glutamine. (iii) Mutant tRNAs carrying formylmethionine are significantly more active in initiation than those carrying formylglutamine. Consequently, a subset of mutant tRNAs which are defective in formylation and therefore inactive in initiation when they are aminoacylated with glutamine become partially active when MetRS is overproduced.
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Affiliation(s)
- U Varshney
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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37
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Lacey JC, Wickramasinghe NS, Cook GW. Experimental studies on the origin of the genetic code and the process of protein synthesis: a review update. ORIGINS LIFE EVOL B 1992; 22:243-75. [PMID: 1454353 DOI: 10.1007/bf01810856] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This article is an update of our earlier review (Lacey and Mullins, 1983) in this journal on the origin of the genetic code and the process of protein synthesis. It is our intent to discuss only experimental evidence published since then although there is the necessity to mention the old enough to place the new in context. We do not include theoretical nor hypothetical treatments of the code or protein synthesis. Relevant data regarding the evolution of tRNAs and the recognition of tRNAs by aminoacyl-tRNA-synthetases are discussed. Our present belief is that the code arose based on a core of early assignments which were made on a physico-chemical and anticodonic basis and this was expanded with new assignments later. These late assignments do not necessarily show an amino acid-anticodon relatedness. In spite of the fact that most data suggest a code origin based on amino acid-anticodon relationships, some new data suggesting preferential binding of Arg to its codons are discussed. While information regarding coding is not increasing very rapidly, information regarding the basic chemistry of the process of protein synthesis has increased significantly, principally relating to aminoacylation of mono- and polyribonucleotides. Included in those studies are several which show stereoselective reactions of L-amino acids with nucleotides having D-sugars. Hydrophobic interactions definitely play a role in the preferences which have been observed.
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Affiliation(s)
- J C Lacey
- Department of Biochemistry, University of Alabama, Birminghanm 35294
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38
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Kim S, Schimmel P. Function independence of microhelix aminoacylation from anticodon binding in a class I tRNA synthetase. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49573-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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39
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Normanly J, Ollick T, Abelson J. Eight base changes are sufficient to convert a leucine-inserting tRNA into a serine-inserting tRNA. Proc Natl Acad Sci U S A 1992; 89:5680-4. [PMID: 1608979 PMCID: PMC49356 DOI: 10.1073/pnas.89.12.5680] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Each aminoacyl-tRNA synthetase must functionally distinguish its cognate tRNAs from all others. We have determined the minimum number of changes required to transform a leucine amber suppressor tRNA to serine identity. Eight changes are required. These are located in the acceptor stem and in the D stem.
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Affiliation(s)
- J Normanly
- Division of Biology, California Institute of Technology, Pasadena 91125
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40
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Sherman JM, Rogers MJ, Söll D. Competition of aminoacyl-tRNA synthetases for tRNA ensures the accuracy of aminoacylation. Nucleic Acids Res 1992; 20:2847-52. [PMID: 1377381 PMCID: PMC336931 DOI: 10.1093/nar/20.11.2847] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The accuracy of protein biosynthesis rests on the high fidelity with which aminoacyl-tRNA synthetases discriminate between tRNAs. Correct aminoacylation depends not only on identity elements (nucleotides in certain positions) in tRNA (1), but also on competition between different synthetases for a given tRNA (2). Here we describe in vivo and in vitro experiments which demonstrate how variations in the levels of synthetases and tRNA affect the accuracy of aminoacylation. We show in vivo that concurrent overexpression of Escherichia coli tyrosyl-tRNA synthetase abolishes misacylation of supF tRNA(Tyr) with glutamine in vivo by overproduced glutaminyl-tRNA synthetase. In an in vitro competition assay, we have confirmed that the overproduction mischarging phenomenon observed in vivo is due to competition between the synthetases at the level of aminoacylation. Likewise, we have been able to examine the role competition plays in the identity of a non-suppressor tRNA of ambiguous identity, tRNA(Glu). Finally, with this assay, we show that the identity of a tRNA and the accuracy with which it is recognized depend on the relative affinities of the synthetases for the tRNA. The in vitro competition assay represents a general method of obtaining qualitative information on tRNA identity in a competitive environment (usually only found in vivo) during a defined step in protein biosynthesis, aminoacylation. In addition, we show that the discriminator base (position 73) and the first base of the anticodon are important for recognition by E. coli tyrosyl-tRNA synthetase.
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Affiliation(s)
- J M Sherman
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511
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41
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Abstract
Previous work established that seven-base-pair hairpin microhelices with sequences based on the acceptor stems of alanine, glycine, methionine, and histidine tRNAs can be aminoacylated specifically with their cognate amino acids. To obtain "minimalist" substrates with fewer base pairs, we took advantage of the high thermodynamic stability of RNA tetraloop motifs that are found in ribosomal RNAs. We show here that rationally designed RNA tetraloops with as few as four base pairs are substrates for aminoacylation. Major nucleotide determinants for recognition by the class II synthetases were incorporated into each of the respective tetraloop substrates, resulting in specific aminoacylation by the alanine, glycine, and histidine tRNA synthetases. An analysis of the kinetics of aminoacylation shows that, for the alanine system, the majority of the transition-state stabilization provided by the synthetase-tRNA interaction is reproduced by the interaction of the synthetase with nucleotides in its minimalist tetraloop substrate. In an extension of this work, we also observed specific aminoacylation with the class I methionine tRNA synthetase of RNA tetraloops based on sequences in the acceptor stem of methionine tRNA. Thus, the results demonstrate four different examples where specific aminoacylation is directed by sequences/structures contained in less than half of a turn of an RNA helix.
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Affiliation(s)
- J P Shi
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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42
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Rogers MJ, Adachi T, Inokuchi H, Söll D. Switching tRNA(Gln) identity from glutamine to tryptophan. Proc Natl Acad Sci U S A 1992; 89:3463-7. [PMID: 1565639 PMCID: PMC48888 DOI: 10.1073/pnas.89.8.3463] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The middle base (U35) of the anticodon of tRNA(Gln) is a major element ensuring the accuracy of aminoacylation by Escherichia coli glutaminyl-tRNA synthetase (GlnRS). An opal suppressor of tRNA(Gln) (su+2UGA) containing C35 (anticodon UCA) was isolated by genetic selection and mutagenesis. Suppression of a UGA mutation in the E. coli fol gene followed by N-terminal sequence analysis of purified dihydrofolate reductase showed that this tRNA was an efficient suppressor that inserted predominantly tryptophan. Mutations of the 3-70 base pair (U70 and A3U70) were made. These mutants of su+2UGA are less efficient suppressors and inserted predominantly tryptophan in vivo; alanine insertion was not observed. Mutations of the discriminator nucleotide (A73, U73, C73) result in very weak opal suppressors. Aminoacylation in vitro by E. coli TrpRS of tRNA(Gln) transcripts mutated in the anticodon demonstrate that TrpRS recognizes all three nucleotides of the anticodon. The results show the interchangeability of the glutamine and tryptophan identities by base substitutions in their respective tRNAs. The amber suppressor (anticodon CUA) tRNA(Trp) was known previously to insert predominantly glutamine. We show that the opal suppressor (anticodon UCA) tRNA(Gln) inserts mainly tryptophan. Discrimination by these synthetases for tRNA includes position 35, with recognition of C35 by TrpRS and U35 by GlnRS. As the use of the UGA codon as tryptophan in mycoplasma and in yeast mitochondria is conserved, recognition of the UCA anticodon by TrpRS may also be maintained in evolution.
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MESH Headings
- Amino Acyl-tRNA Synthetases/metabolism
- Anticodon/genetics
- Base Sequence
- Cloning, Molecular
- Escherichia coli/enzymology
- Escherichia coli/genetics
- Genes, Bacterial
- Genes, Suppressor
- Genes, Synthetic
- Glutamine/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Nucleic Acid Conformation
- RNA, Transfer, Gln/genetics
- RNA, Transfer, Gln/metabolism
- Suppression, Genetic
- Tetrahydrofolate Dehydrogenase/biosynthesis
- Tetrahydrofolate Dehydrogenase/genetics
- Tetrahydrofolate Dehydrogenase/isolation & purification
- Tryptophan/metabolism
- beta-Galactosidase/genetics
- beta-Galactosidase/metabolism
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Affiliation(s)
- M J Rogers
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511
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43
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Pallanck L, Li S, Schulman L. The anticodon and discriminator base are major determinants of cysteine tRNA identity in vivo. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42508-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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44
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Martinis SA, Schimmel P. Enzymatic aminoacylation of sequence-specific RNA minihelices and hybrid duplexes with methionine. Proc Natl Acad Sci U S A 1992; 89:65-9. [PMID: 1729719 PMCID: PMC48176 DOI: 10.1073/pnas.89.1.65] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
RNA hairpin helices whose sequences are based on the acceptor stems of alanine and histidine tRNAs are specifically aminoacylated with their cognate amino acids. In these examples, major determinants for the identities of the respective tRNAs reside in the acceptor stem; the anticodon and other parts of the tRNA are dispensable for aminoacylation. In contrast, the anticodon is a major determinant for the identity of a methionine tRNA. RNA hairpin helices and hybrid duplexes that reconstruct the acceptor-T psi C stem and the acceptor stem, respectively, of methionine tRNA were investigated here for aminoacylation with methionine. Direct visualization of the aminoacylated RNA product on an acidic polyacrylamide gel by phosphor imaging demonstrated specific aminoacylation with substrates that contained as few as 7 base pairs. No aminoacylation with methionine was detected with several analogous RNA substrates whose sequences were based on noncognate tRNAs. While the efficiency of aminoacylation is reduced by orders of magnitude relative to methionine tRNA, the results establish that specific aminoacylation with methionine of small duplex substrates can be achieved without the anticodon or other domains of the tRNA. The results, combined with earlier studies, suggest a highly specific adaptation of the structures of aminoacyl-tRNA synthetases to the acceptor stems of their cognate tRNAs, resulting in a relationship between the nucleotide sequences/structures of small RNA duplexes and specific amino acids.
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Affiliation(s)
- S A Martinis
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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45
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Recognition of †RNAs by Aminoacyl-†RNA Synthetases. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1991. [DOI: 10.1016/s0079-6603(08)60006-9] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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