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Kim Y, Cho S, Kim JC, Park HS. tRNA engineering strategies for genetic code expansion. Front Genet 2024; 15:1373250. [PMID: 38516376 PMCID: PMC10954879 DOI: 10.3389/fgene.2024.1373250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 02/26/2024] [Indexed: 03/23/2024] Open
Abstract
The advancement of genetic code expansion (GCE) technology is attributed to the establishment of specific aminoacyl-tRNA synthetase/tRNA pairs. While earlier improvements mainly focused on aminoacyl-tRNA synthetases, recent studies have highlighted the importance of optimizing tRNA sequences to enhance both unnatural amino acid incorporation efficiency and orthogonality. Given the crucial role of tRNAs in the translation process and their substantial impact on overall GCE efficiency, ongoing efforts are dedicated to the development of tRNA engineering techniques. This review explores diverse tRNA engineering approaches and provides illustrative examples in the context of GCE, offering insights into the user-friendly implementation of GCE technology.
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Affiliation(s)
| | | | | | - Hee-Sung Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
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2
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Fan C, Xiong H, Reynolds NM, Söll D. Rationally evolving tRNAPyl for efficient incorporation of noncanonical amino acids. Nucleic Acids Res 2015; 43:e156. [PMID: 26250114 PMCID: PMC4678846 DOI: 10.1093/nar/gkv800] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/27/2015] [Indexed: 12/29/2022] Open
Abstract
Genetic encoding of noncanonical amino acids (ncAAs) into proteins is a powerful approach to study protein functions. Pyrrolysyl-tRNA synthetase (PylRS), a polyspecific aminoacyl-tRNA synthetase in wide use, has facilitated incorporation of a large number of different ncAAs into proteins to date. To make this process more efficient, we rationally evolved tRNAPyl to create tRNAPyl-opt with six nucleotide changes. This improved tRNA was tested as substrate for wild-type PylRS as well as three characterized PylRS variants (Nϵ-acetyllysyl-tRNA synthetase [AcKRS], 3-iodo-phenylalanyl-tRNA synthetase [IFRS], a broad specific PylRS variant [PylRS-AA]) to incorporate ncAAs at UAG codons in super-folder green fluorescence protein (sfGFP). tRNAPyl-opt facilitated a 5-fold increase in AcK incorporation into two positions of sfGFP simultaneously. In addition, AcK incorporation into two target proteins (Escherichia coli malate dehydrogenase and human histone H3) caused homogenous acetylation at multiple lysine residues in high yield. Using tRNAPyl-opt with PylRS and various PylRS variants facilitated efficient incorporation of six other ncAAs into sfGFP. Kinetic analyses revealed that the mutations in tRNAPyl-opt had no significant effect on the catalytic efficiency and substrate binding of PylRS enzymes. Thus tRNAPyl-opt should be an excellent replacement of wild-type tRNAPyl for future ncAA incorporation by PylRS enzymes.
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Affiliation(s)
- Chenguang Fan
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8144, USA
| | - Hai Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8144, USA
| | - Noah M Reynolds
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8144, USA
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8144, USA Department of Chemistry, Yale University, New Haven, CT 06520-8144, USA
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3
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Negrutskii BS, El'skaya AV. Eukaryotic translation elongation factor 1 alpha: structure, expression, functions, and possible role in aminoacyl-tRNA channeling. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1998; 60:47-78. [PMID: 9594571 DOI: 10.1016/s0079-6603(08)60889-2] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This review offers a comprehensive analysis of eukaryotic translation elongation factor 1 (eEF-1 alpha) in comparison with its bacterial counterpart EF-Tu. Altogether, the data presented indicate some variances in the elongation process in prokaryotes and eukaryotes. The differences may be attributed to translational channeling and compartmentalization of protein synthesis in higher eukaryotic cells. The functional importance of the EF-1 multisubunit complex and expression of its subunits under miscellaneous cellular conditions are reviewed. A number of novel functions of EF-1 alpha, which may contribute to the coordinate regulation of multiple cellular processes including growth, division, and transformation, are characterized.
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Affiliation(s)
- B S Negrutskii
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kiev, Ukraine
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4
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Nawrot B, Hillenbrand R, Limmer S, Grillenbeck N, Sprinzl M. Interaction of N-tosyl-L-phenylalanylchloromethane with Thermus thermophilus elongation factor Tu. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 247:59-65. [PMID: 9249009 DOI: 10.1111/j.1432-1033.1997.t01-1-00059.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The interaction of N-tosyl-L-phenylalanylchloromethane (TosPheCH2Cl) with Thermus thermophilus elongation factor Tu (EF-Tu) was studied by affinity labelling and NMR spectroscopy. TosPheCH2Cl binds to GDP and GTP conformers of EF-Tu. The interaction of TosPheCH2Cl with EF-Tu x GDP leads to alkylation of Cys82, while interaction of TosPheCH2Cl with EF-Tu x GTP does not lead to covalent labelling. [A82]EF-Tu, in which the Cys82 is replaced by Ala, has similar properties to wild-type EF-Tu with respect to GTPase activity, binding of guanine nucleotides, interaction with elongation factor Ts (EF-Ts) and interaction with ribosomes. This structural change did not lead to changes, compared with wild-type EF-Tu in the functionality of [A82]EF-Tu, either in the GTP or in the GDP conformation. TosPheCH2Cl binds to EF-Tu x GTP with a dissociation constant of 10 microM. The interaction of TosPheCH2Cl with EF-Tu promotes the hydration of the carbonyl group of TosPheCH2Cl. TosPheCH2Cl competes with aminoacyl-tRNA for its binding site on EF-Tu x GTP. Covalent modification of Cys82 by TosPheCH2Cl does not prevent nucleotide binding and GTPase activity, but interferes with the interaction with aminoacyl-tRNA. TosPheCH2Cl probably mimics the aminoacyl residue of the aminoacyl-tRNA and binds to its binding site on EF-Tu x GTP. This rather specific interaction with EF-Tu x GTP does not allow the modification of Cys82, whereas the loose interaction of TosPheCH2Cl with EF-Tu x GDP leads to alkylation of this residue.
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Affiliation(s)
- B Nawrot
- Laboratorium für Biochemie, Universität Bayreuth, Germany
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5
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Liu G, Tang J, Edmonds BT, Murray J, Levin S, Condeelis J. F-actin sequesters elongation factor 1alpha from interaction with aminoacyl-tRNA in a pH-dependent reaction. J Biophys Biochem Cytol 1996; 135:953-63. [PMID: 8922379 PMCID: PMC2133385 DOI: 10.1083/jcb.135.4.953] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The machinery of eukaryotic protein synthesis is found in association with the actin cytoskeleton. A major component of this translational apparatus, which is involved in the shuttling of aa-tRNA, is the actin-binding protein elongation factor 1alpha (EF-1alpha). To investigate the consequences for translation of the interaction of EF-1alpha with F-actin, we have studied the effect of F-actin on the ability of EF-1alpha to bind to aa-tRNA. We demonstrate that binding of EF-1alpha:GTP to aa-tRNA is not pH sensitive with a constant binding affinity of approximately 0.2 microM over the physiological range of pH. However, the sharp pH dependence of binding of EF-1alpha to F-actin is sufficient to shift the binding of EF-1alpha from F-actin to aa-tRNA as pH increases. The ability of EF-1alpha to bind either F-actin or aa-tRNA in competition binding experiments is also consistent with the observation that EF-1alpha's binding to F-actin and aa-tRNA is mutually exclusive. Two pH-sensitive actin-binding sequences in EF-1alpha are identified and are predicted to overlap with the aa-tRNA-binding sites. Our results suggest that pH-regulated recruitment and release of EF-1alpha from actin filaments in vivo will supply a high local concentration of EF-1alpha to facilitate polypeptide elongation by the F-actin-associated translational apparatus.
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Affiliation(s)
- G Liu
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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6
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Khan R, Chang HO, Kaluarachchi K, Giedroc DP. Interaction of retroviral nucleocapsid proteins with transfer RNAPhe: a lead ribozyme and 1H NMR study. Nucleic Acids Res 1996; 24:3568-75. [PMID: 8836184 PMCID: PMC146139 DOI: 10.1093/nar/24.18.3568] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In the initiation of reverse transcription in retroviruses, nucleocapsid (NC) protein accelerates the rate of annealing of transfer RNA replication primer to a complementary sequence on the genomic RNA. In this report, we have probed the conformational changes induced by HIV-1 NC protein and domain deletion mutants in a structurally well-characterized transfer RNA, yeast tRNAPhe, as a model for the natural primer. One molar equivalent of recombinant 71 amino acid HIV-1 nucleocapsid protein (NC 1-71) is sufficient to completely inhibit the Pb2(+)-ribozyme activity of tRNAPhe at 25 degrees C, pH 7.0 and 15 mM MgCl2, Zn2 HIV-1 NC proteins which lack one or both flexible terminal domains also inhibit the ribozyme activity. 1H NMR spectra acquired for Mg(2+)-tRNAPhe suggest that NC 1-71 and NC 12-55 (lacking residues 1-11 and 56-71) inhibit the lead-ribozyme activity by only modestly altering the active site region rather than inducing large-scale unfolding of the molecule. In the absence of Mg2+, the extent of destabilization of tRNAPhe is greater but appears to be confined to internal regions of the acceptor and T psi C helices, as evidenced by the selectively enhanced exchange rates for imino protons associated with these base pairs. These findings show that NC destabilizes the folded form of tRNAPhe and by extension, other complex RNAs, in tertiary and secondary structural regions most susceptible to thermally-induced denaturation.
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Affiliation(s)
- R Khan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843-2128, USA
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7
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Enríquez JA, Attardi G. Evidence for aminoacylation-induced conformational changes in human mitochondrial tRNAs. Proc Natl Acad Sci U S A 1996; 93:8300-5. [PMID: 8710865 PMCID: PMC38665 DOI: 10.1073/pnas.93.16.8300] [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: 02/01/2023] Open
Abstract
Analysis by acid polyacrylamide/urea gel electrophoresis of 14 individual mitochondrial tRNAs (mt-tRNAs) from human cells has revealed a variable decrease in mobility of the aminoacylated relative to the nonacylated form, with the degree of separation of the two forms not being correlated with the mass, polar character, or charge of the amino acid. Separation of the charged and uncharged species has been found to be independent of tRNA denaturation, being observed also in the absence of urea. In another approach, electrophoresis through a perpendicular denaturing gradient gel of several individual mt-tRNAs has shown a progressive unfolding of the tRNA with increasing denaturant concentration, which is consistent with an initial disruption of tertiary interactions, followed by the sequential melting of the four stems of the cloverleaf structure. A detailed analysis of the unfolding process of charged and uncharged tRNALys and tRNALeu(UUR) has revealed that the separation of the two forms of these tRNAs persisted throughout the almost entire range of denaturant concentrations used and was lost upon denaturation of the last helical domain(s), which most likely included the amino acid acceptor stem. These observations strongly suggest that the electrophoretic retardation of the charged species reflects an aminoacylation-induced conformational change of the 3'-end of these mt-tRNAs, with possible significant implications in connection with the known role of the acceptor end in tRNA interactions with the ribosomal peptidyl transferase center and the elongation factor Tu.
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Affiliation(s)
- J A Enríquez
- Division of Biology, California Institute of Technology, Pasadena 91125, USA
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8
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Laalami S, Grentzmann G, Bremaud L, Cenatiempo Y. Messenger RNA translation in prokaryotes: GTPase centers associated with translational factors. Biochimie 1996; 78:577-89. [PMID: 8955901 DOI: 10.1016/s0300-9084(96)80004-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
During the decoding of messenger RNA, each step of the translational cycle requires the intervention of protein factors and the hydrolysis of one or more GTP molecule(s). Of the prokaryotic translational factors, IF2, EF-Tu, SELB, EF-G and RF3 are GTP-binding proteins. In this review we summarize the latest findings on the structures and the roles of these GTPases in the translational process.
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Affiliation(s)
- S Laalami
- Institut de Biologie Moléculaire et d'Ingénierie Génétique, URA-CNRS 1172, Université de Poitiers, France
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9
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Ahmadian MR, Kreutzer R, Blechschmidt B, Sprinzl M. Site-directed mutagenesis of Thermus thermophilus EF-Tu: the substitution of threonine-62 by serine or alanine. FEBS Lett 1995; 377:253-7. [PMID: 8543062 DOI: 10.1016/0014-5793(95)01354-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The invariant threonine-62, which occurs in the effector region of all GTP/GDP-binding regulatory proteins, was substituted via site-directed mutagenesis by alanine and serine in the elongation factor Tu from Thermus thermophilus. The altered proteins were overproduced in Escherichia coli, purified and characterized. The EF-Tu T62S variant had similar properties with respect to thermostability, aminoacyl-tRNA binding, GTPase activity and in vitro translation as the wild-type EF-Tu. In contrast, EF-Tu T62A is severely impaired in its ability to sustain polypeptide synthesis and has only very low intrinsic and ribosome-induced GTPase activity. The affinity of aminoacyl-tRNA to the EF-Tu T62A.GTP complex is almost 40 times lower as compared to the native EF-Tu.GTP. These observations are in agreement with the tertiary structure of EF-Tu.GTP, in which threonine-62 is interacting with the Mg2+ ion, gamma-phosphate of GTP and a water molecule, which is presumably involved in the GTP hydrolysis.
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Affiliation(s)
- M R Ahmadian
- Laboratorium für Biochemie Universität Bayreuth, Germany
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10
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Nissen P, Kjeldgaard M, Thirup S, Polekhina G, Reshetnikova L, Clark BF, Nyborg J. Crystal structure of the ternary complex of Phe-tRNAPhe, EF-Tu, and a GTP analog. Science 1995; 270:1464-72. [PMID: 7491491 DOI: 10.1126/science.270.5241.1464] [Citation(s) in RCA: 652] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The structure of the ternary complex consisting of yeast phenylalanyl-transfer RNA (Phe-tRNAPhe), Thermus aquaticus elongation factor Tu (EF-Tu), and the guanosine triphosphate (GTP) analog GDPNP was determined by x-ray crystallography at 2.7 angstrom resolution. The ternary complex participates in placing the amino acids in their correct order when messenger RNA is translated into a protein sequence on the ribosome. The EF-Tu-GDPNP component binds to one side of the acceptor helix of Phe-tRNAPhe involving all three domains of EF-Tu. Binding sites for the phenylalanylated CCA end and the phosphorylated 5' end are located at domain interfaces, whereas the T stem interacts with the surface of the beta-barrel domain 3. The binding involves many conserved residues in EF-Tu. The overall shape of the ternary complex is similar to that of the translocation factor, EF-G-GDP, and this suggests a novel mechanism involving "molecular mimicry" in the translational apparatus.
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Affiliation(s)
- P Nissen
- Department of Biostructural Chemistry, Institute of Chemistry, Aarhus University, Denmark
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11
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Abstract
The past year has witnessed a tremendous increase in our understanding of the structures and interactions of the GTPases. The highlights include crystal structures of G alpha subunits, as well as the first complex between a GTPase (Rap1A) and an effector molecule (c-Raf1 Ras-binding domain). In the field of elongation factors (EFs), three very important structures have been determined: EF-G, the ternary complex of EF-Tu.GTP with aminoacyl-tRNA, and the EF-Tu.EF-Ts complex.
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Affiliation(s)
- R Hilgenfeld
- Institute of Molecular Biotechnology, Jena, Germany
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12
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Nock S, Grillenbeck N, Ahmadian MR, Ribeiro S, Kreutzer R, Sprinzl M. Properties of isolated domains of the elongation factor Tu from Thermus thermophilus HB8. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 234:132-9. [PMID: 8529632 DOI: 10.1111/j.1432-1033.1995.00132.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The relative contributions of the three domains of elongation factor Tu (EF-Tu) to the factor's function and thermal stability were established by dissecting the domains apart with recombination techniques. Domain I (EF-TuI), domains I/II (EF-TuI/II) and domain III (EF-TuIII) of the EF-Tu from Thermus thermophilus HB8 comprising the amino acids 1-211, 1-312 and 317-405, respectively, were overproduced in Escherichia coli and purified. A polypeptide consisting of domain II and III (EF-TuII/III) was prepared by limited proteolysis of native EF-Tu with V8 protease from Staphylococcus aureus [Peter, M. E., Reiser, C. O. A., Schirmer, N. K., Kiefhaber, T., Ott, G., Grillenbeck, N. W. & Sprinzl, M. (1990) Nucleic Acids Res. 18, 6889-6893]. As determined by circular dichroism spectrometry, the isolated domains have the secondary structure elements found in the native EF-Tu. GTP and GDP binding as well as GTPase activity are maintained by the EF-TuI and EF-TuI/II; however, the rate of GDP dissociation from EF-TuI . GDP and EF-TuI/II . GDP complex is increased as compared to native EF-Tu . GDP, reflecting a constraint imposed by domain III on the ability to release the nucleotide from its binding pocket located in domain I. A weak interaction of Tyr-tRNATyr with the EF-TuI . GTP suggests that domain I provides a part of the structure interacting with aminoacyl-tRNA. The domain III is capable of regulating the rate of GTPase in EF-Tu, since the polypeptide consisting only of domains I/II has a 39-fold higher intrinsic GTPase compared to the native EF-Tu. No in vitro poly(U)-dependent poly(Phe) synthesis was detectable with a mixture of equimolar amounts of domains I/II and domain III, demonstrating the necessity of covalent linkage between the domains of EF-Tu for polypeptide synthesis. In contrast to native EF-Tu and EF-TuII/III, EF-TuI and, to a lesser extent the polypeptide consisting of domains I/II, are unstable at elevated temperatures. This indicates that domains II/III strongly contribute to the thermal stability of this T. thermophilus EF-Tu. Deletion of amino acid residues 181-190 from domain I of T. thermophilus EF-Tu decreases the thermostability to that of EF-Tu from E. coli, which does not have these residues. Interdomain interactions must be important for the stabilisation of the structure of domain I, since isolated T. thermophilus EF-TuI is thermolabile despite the presence of the 181-190 loop.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Nock
- Lehrstuhl für Biochemie, Universität Bayreuth, Germany
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13
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Watson BS, Hazlett TL, Eccleston JF, Davis C, Jameson DM, Johnson AE. Macromolecular arrangement in the aminoacyl-tRNA.elongation factor Tu.GTP ternary complex. A fluorescence energy transfer study. Biochemistry 1995; 34:7904-12. [PMID: 7794902 DOI: 10.1021/bi00024a015] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The distance between the corner of the L-shaped transfer RNA and the GTP bound to elongation factor Tu (EF-Tu) in the aminoacyl-tRNA.EF-Tu.GTP ternary complex was measured using fluorescence energy transfer. The donor dye, fluorescein (Fl), was attached covalently to the 4-thiouridine base at position 8 of tRNAPhe, and aminoacylation yielded Phe-tRNAPhe-Fl8. The ribose of GTP was covalently modified at the 2'(3') position with the acceptor dye rhodamine (Rh) to form GTP-Rh. Formation of the Phe-tRNAPhe-Fl8.EF-Tu.GTP-Rh ternary complex was verified both by EF-Tu protection of the aminoacyl bond from chemical hydrolysis and by an EF-Tu.GTP-dependent increase in fluorescein intensity. Spectral analyses revealed that both the emission intensity and lifetime of fluorescein were greater in the Phe-tRNAPhe-Fl8.EF-Tu.GTP ternary complex than in the Phe-tRNAPhe-Fl8.EF-Tu.GTP-Rh ternary complex. These spectral differences disappeared when excess GTP was added to replace GTP-Rh in the latter ternary complex, thereby showing that excited-state energy was transferred from fluorescein to rhodamine in the ternary complex. The efficiency of singlet-singlet energy transfer was low (10-12%), corresponding to a distance between the donor and acceptor dyes in the ternary complex of 70 +/- 7 A, where the indicated uncertainty reflects the uncertainty in dye orientation. After correction for the lengths of the probe attachment tethers, the 2'(3')-oxygen of the GTP ribose and the sulfur in the s4U are separated by a minimum of 49 A. This large distance limits the possible arrangements of the EF-Tu and the tRNA in the ternary complex.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- B S Watson
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman 73019, USA
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14
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Alexander C, Bilgin N, Lindschau C, Mesters JR, Kraal B, Hilgenfeld R, Erdmann VA, Lippmann C. Phosphorylation of elongation factor Tu prevents ternary complex formation. J Biol Chem 1995; 270:14541-7. [PMID: 7782317 DOI: 10.1074/jbc.270.24.14541] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The elongation factor Tu (EF-Tu) is a member of the GTP/GDP-binding proteins and interacts with various partners during the elongation cycle of protein biosynthesis thereby mediating the correct binding of amino-acylated transfer RNA (aa-tRNA) to the acceptor site (A-site) of the ribosome. After GTP hydrolysis EF-Tu is released in its GDP-bound state. In vivo, EF-Tu is post-translationally modified by phosphorylation. Here we report that the phosphorylation of EF-Tu by a ribosome associated kinase activity is drastically enhanced by EF-Ts. The antibiotic kirromycin, known to block EF-Tu function, inhibits the modification. This effect is specific, since kirromycin-resistant mutants do become phosphorylated in the presence of the antibiotic. On the other hand, phosphorylated wild-type EF-Tu does not bind kirromycin. Most interestingly, the phosphorylation of EF-Tu abolishes its ability to bind aa-tRNA. In the GTP conformation the site of modification is located at the interface between domains 1 and 3 and is involved in a strong interdomain hydrogen bond. Introduction of a charged phosphate group at this position will change the interaction between the domains, leading to an opening of the molecule reminiscent of the GDP conformation. A model for the function of EF-Tu phosphorylation in protein biosynthesis is presented.
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Affiliation(s)
- C Alexander
- Institut für Biochemie, Freie Universität Berlin, Dahlem, Germany
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15
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Nissen P, Reshetnikova L, Siboska G, Polekhina G, Thirup S, Kjeldgaard M, Clark BF, Nyborg J. Purification and crystallization of the ternary complex of elongation factor Tu:GTP and Phe-tRNA(Phe). FEBS Lett 1994; 356:165-8. [PMID: 7805830 DOI: 10.1016/0014-5793(94)01254-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Elongation factor Tu (EF-Tu) is the most abundant protein in prokaryotic cells. Its general function in protein biosynthesis is well established. It is a member of the large family of G-proteins, all of which bind guanosine phosphates (GDP or GTP) as cofactors. In its active GTP bound state EF-Tu binds aminoacylated tRNA (aa-tRNA) forming the ternary complex EF-Tu:GTP:aa-tRNA. The ternary complex interacts with the ribosome where the anticodon on tRNA recognises a codon on mRNA, GTPase activity is induced and inactive EF-Tu:GDP is released. Here we report the successful crystallization of a ternary complex of Thermus aquaticus EF-Tu:GDPNP and yeast Phe-tRNA(Phe) after its purification by HPLC.
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MESH Headings
- Chromatography, Gel
- Chromatography, High Pressure Liquid
- Crystallization
- Crystallography, X-Ray
- Electrophoresis, Polyacrylamide Gel
- Guanosine Triphosphate/chemistry
- Guanosine Triphosphate/isolation & purification
- Guanosine Triphosphate/metabolism
- Guanylyl Imidodiphosphate/metabolism
- Peptide Elongation Factor Tu/chemistry
- Peptide Elongation Factor Tu/isolation & purification
- Peptide Elongation Factor Tu/metabolism
- RNA, Transfer, Phe/chemistry
- RNA, Transfer, Phe/isolation & purification
- RNA, Transfer, Phe/metabolism
- Saccharomyces cerevisiae/metabolism
- Thermus/metabolism
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Affiliation(s)
- P Nissen
- Department of Biostructural Chemistry, University of Aarhus, Denmark
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16
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Abstract
Several elongation factors involved in protein synthesis are GTPases that share structural and mechanistic homology with the large family of proteins including Ras and heterotrimeric receptor-coupled G proteins. The structure of elongation factor Tu (EF-Tu) from thermophilic bacteria, in its 'active' GTP-bound form, has recently been solved by X-ray crystallography. Comparison of this structure with the structure of Escherichia coli EF-Tu bound to GDP reveals a dramatic conformational change that is dependent on GTPase activity. The mechanism of this conformational change and of GTPase activation are discussed, and a model for the EF-Tu-GTP complex with aminoacyl-tRNA is presented.
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Affiliation(s)
- M Sprinzl
- Laboratorium für Biochemie, Universität Bayreuth, Germany
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