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Fung AWS, Payoe R, Fahlman RP. Perspectives and Insights into the Competition for Aminoacyl-tRNAs between the Translational Machinery and for tRNA Dependent Non-Ribosomal Peptide Bond Formation. Life (Basel) 2015; 6:life6010002. [PMID: 26729173 PMCID: PMC4810233 DOI: 10.3390/life6010002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 12/23/2015] [Accepted: 12/25/2015] [Indexed: 12/19/2022] Open
Abstract
Aminoacyl-tRNA protein transferases catalyze the transfer of amino acids from aminoacyl-tRNAs to polypeptide substrates. Different forms of these enzymes are found in the different kingdoms of life and have been identified to be central to a wide variety of cellular processes. L/F-transferase is the sole member of this class of enzyme found in Escherichia coli and catalyzes the transfer of leucine to the N-termini of proteins which result in the targeted degradation of the modified protein. Recent investigations on the tRNA specificity of L/F-transferase have revealed the unique recognition nucleotides for a preferred Leu-tRNALeu isoacceptor substrate. In addition to discussing this tRNA selectivity by L/F-transferase, we present and discuss a hypothesis and its implications regarding the apparent competition for this aminoacyl-tRNA between L/F-transferase and the translational machinery. Our discussion reveals a hypothetical involvement of the bacterial stringent response that occurs upon amino acid limitation as a potential cellular event that may reduce this competition and provide the opportunity for L/F-transferase to readily increase its access to the pool of aminoacylated tRNA substrates.
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Affiliation(s)
- Angela W S Fung
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, 474-MSB Edmonton, AB T6G 2H7, Canada.
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A1, Canada.
| | - Roshani Payoe
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, 474-MSB Edmonton, AB T6G 2H7, Canada.
- Institute of Technology, Faculty of Science and Technology, University of Tartu, Noorse St 1, Tartu 50411, Estonia.
| | - Richard P Fahlman
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, 474-MSB Edmonton, AB T6G 2H7, Canada.
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Taki M, Kuroiwa H. Unexpectedly fast transfer of positron-emittable artificial substrate into N-terminus of peptide/protein mediated by wild-type L/F-tRNA-protein transferase. Amino Acids 2015; 47:1279-82. [PMID: 25929586 DOI: 10.1007/s00726-015-1989-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 04/14/2015] [Indexed: 01/09/2023]
Abstract
This article demonstrates the fastest enzymatic introduction of a positron emission tomography (PET) probe into acceptor peptides/proteins. It is site-specifically introduced at the basic N-terminus of the acceptors by using L/F-transferase in combination with aminoacyl-tRNA synthetase, namely the NEXT-A/PET reaction. Estimated from kinetic analysis, the transfer efficiency of O-(2-fluoromethyl)-L-tyrosine as an artificial amino acid PET probe mediated by the wild-type transferase is almost as good as that of the natural substrate, phenylalanine.
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Affiliation(s)
- Masumi Taki
- Division of Chemistry and Biochemistry, Department of Medical and Bioengineering Science, Chemical Biology Area, Okayama University, 1-1-1, Tsushimanaka, Okayama, 700-0082, Japan,
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Abstract
Arginylation is an enzymatic reaction in which arginyl-tRNA protein transferase 1 (ATE1, EC 2.3.2.8) conjugates a single arginyl moiety from aminoacylated tRNA(Arg) onto a target polypeptide. We established arginylation for in vitro labeling of peptides with N-terminal acidic amino acids. Consistent with prior knowledge, arginylated peptides flanked by basic amino acids result in rich redundant MS/MS fragment spectra using various precursor fragmentation modes. Arginylation carried out by ATE1 is a fast method for labeling peptides. Sequence-specific proteolytic digest of proteins is best carried out using a double digest of proteins by Lys-C and Asp-N to generate peptides with a basic amino acid on the C-terminus and an acidic amino acid on the N-terminus. Under these conditions, arginylation is specific for N-terminal acidic amino acids and results in a near 2× sequence coverage in the MS/MS spectrum are achieved.
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Affiliation(s)
- H Alexander Ebhardt
- Institute of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zürich, HPT E 61, Auguste-Piccard-Hof 1, 8093, Zürich, Switzerland,
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Ebhardt HA, Nan J, Chaulk SG, Fahlman RP, Aebersold R. Enzymatic generation of peptides flanked by basic amino acids to obtain MS/MS spectra with 2× sequence coverage. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:2735-2743. [PMID: 25380496 PMCID: PMC4241039 DOI: 10.1002/rcm.7069] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 10/01/2014] [Accepted: 10/02/2014] [Indexed: 06/04/2023]
Abstract
RATIONALE Tandem mass (MS/MS) spectra generated by collision-induced dissociation (CID) typically lack redundant peptide sequence information in the form of e.g. b- and y-ion series due to frequent use of sequence-specific endopeptidases cleaving C- or N-terminal to Arg or Lys residues. METHODS Here we introduce arginyl-tRNA protein transferase (ATE, EC 2.3.2.8) for proteomics. ATE recognizes acidic amino acids or oxidized Cys at the N-terminus of a substrate peptide and conjugates an arginine from an aminoacylated tRNA(Arg) onto the N-terminus of the substrate peptide. This enzymatic reaction is carried out under physiological conditions and, in combination with Lys-C/Asp-N double digest, results in arginylated peptides with basic amino acids on both termini. RESULTS We demonstrate that in vitro arginylation of peptides using yeast arginyl tRNA protein transferase 1 (yATE1) is a robust enzymatic reaction, specific to only modifying N-terminal acidic amino acids. Precursors originating from arginylated peptides generally have an increased protonation state compared with their non-arginylated forms. Furthermore, the product ion spectra of arginylated peptides show near complete 2× fragment ladders within the same MS/MS spectrum using commonly available electrospray ionization peptide fragmentation modes. Unexpectedly, arginylated peptides generate complete y- and c-ion series using electron transfer dissociation (ETD) despite having an internal proline residue. CONCLUSIONS We introduce a rapid enzymatic method to generate peptides flanked on either terminus by basic amino acids, resulting in a rich, redundant MS/MS fragment pattern.
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Affiliation(s)
- H Alexander Ebhardt
- Department of Biology, Institute of Molecular Systems Biology, ETH ZürichAuguste-Piccard-Hof 1, 8093, Zürich, Switzerland
| | - Jie Nan
- Department of Biology, Institute of Molecular Systems Biology, ETH ZürichAuguste-Piccard-Hof 1, 8093, Zürich, Switzerland
| | - Steven G Chaulk
- Department of Biochemistry, University of AlbertaEdmonton, Alberta, Canada
| | - Richard P Fahlman
- Department of Biochemistry, University of AlbertaEdmonton, Alberta, Canada
- Department of Oncology, University of AlbertaEdmonton, Alberta, Canada
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, ETH ZürichAuguste-Piccard-Hof 1, 8093, Zürich, Switzerland
- Competence Center for Systems Physiology and Metabolic DiseasesZürich, Switzerland
- Faculty of Science, University of ZürichZürich, Switzerland
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Warner JB, Muthusamy AK, Petersson EJ. Specific modulation of protein activity by using a bioorthogonal reaction. Chembiochem 2014; 15:2508-14. [PMID: 25256385 DOI: 10.1002/cbic.201402423] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Indexed: 11/06/2022]
Abstract
Unnatural amino acids with bioorthogonal reactive groups have the potential to provide a rapid and specific mechanism for covalently inhibiting a protein of interest. Here, we use mutagenesis to insert an unnatural amino acid containing an azide group (Z) into the target protein at positions such that a "click" reaction with an alkyne modulator (X) will alter the function of the protein. This bioorthogonally reactive pair can engender specificity of X for the Z-containing protein, even if the target is otherwise identical to another protein, allowing for rapid target validation in living cells. We demonstrate our method using inhibition of the Escherichia coli enzyme aminoacyl transferase by both active-site occlusion and allosteric mechanisms. We have termed this a "clickable magic bullet" strategy, and it should be generally applicable to studying the effects of protein inhibition, within the limits of unnatural amino acid mutagenesis.
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Affiliation(s)
- John B Warner
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104-6323 (USA)
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Fung AWS, Leung CCY, Fahlman RP. The determination of tRNALeu recognition nucleotides for Escherichia coli L/F transferase. RNA (NEW YORK, N.Y.) 2014; 20:1210-1222. [PMID: 24935875 PMCID: PMC4105747 DOI: 10.1261/rna.044529.114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/28/2014] [Indexed: 06/03/2023]
Abstract
Escherichia coli leucyl/phenylalanyl-tRNA protein transferase catalyzes the tRNA-dependent post-translational addition of amino acids onto the N-terminus of a protein polypeptide substrate. Based on biochemical and structural studies, the current tRNA recognition model by L/F transferase involves the identity of the 3' aminoacyl adenosine and the sequence-independent docking of the D-stem of an aminoacyl-tRNA to the positively charged cluster on L/F transferase. However, this model does not explain the isoacceptor preference observed 40 yr ago. Using in vitro-transcribed tRNA and quantitative MALDI-ToF MS enzyme activity assays, we have confirmed that, indeed, there is a strong preference for the most abundant leucyl-tRNA, tRNA(Leu) (anticodon 5'-CAG-3') isoacceptor for L/F transferase activity. We further investigate the molecular mechanism for this preference using hybrid tRNA constructs. We identified two independent sequence elements in the acceptor stem of tRNA(Leu) (CAG)-a G₃:C₇₀ base pair and a set of 4 nt (C₇₂, A₄:U₆₉, C₆₈)-that are important for the optimal binding and catalysis by L/F transferase. This maps a more specific, sequence-dependent tRNA recognition model of L/F transferase than previously proposed.
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Affiliation(s)
- Angela Wai Shan Fung
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | | | - Richard Peter Fahlman
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7 Department of Oncology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Kawaguchi J, Maejima K, Kuroiwa H, Taki M. Kinetic analysis of the leucyl/phenylalanyl-tRNA-protein transferase with acceptor peptides possessing different N-terminal penultimate residues. FEBS Open Bio 2013; 3:252-5. [PMID: 23905007 PMCID: PMC3722611 DOI: 10.1016/j.fob.2013.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 06/05/2013] [Accepted: 06/06/2013] [Indexed: 11/20/2022] Open
Abstract
The introduction of non-natural amino acids at the N-terminus of peptides/proteins using leucyl/phenylalanyl-tRNA-protein transferase (L/F-transferase) is a useful technique for protein engineering. To accelerate the chemoenzymatic reaction, here we systematically optimized the N-terminal penultimate residue of the acceptor peptide. Positively charged, small, or hydrophilic amino acids at this position show positive effects for the reaction. Kinetic analysis of peptides possessing different penultimate residues suggests that the side chain of the residue affects peptide-binding affinity towards the L/F-transferase. These findings also provide biological insight into the effect of the penultimate amino acid on substrate specificity of natural proteins to be degraded via the N-end rule pathway. A systematic kinetic analysis of L/F-transferase with different acceptor peptides. L/F-transferase discriminates the N-terminal penultimate residue of substrate peptides. The side chain of this residue affects the peptide binding affinity for L/F-transferase. Ser or Arg is this position optimizes introduction of non-natural amino acids into peptides The N-terminal penultimate residue of a protein may affect its stability in vivo.
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Affiliation(s)
- Jun Kawaguchi
- Department of Engineering Science, Bioscience and Technology Program, The Graduate School of Informatics and Engineering, The University of Electro-Communications (UEC), 7-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
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Wagner AM, Fegley MW, Warner JB, Grindley CLJ, Marotta NP, Petersson EJ. N-terminal protein modification using simple aminoacyl transferase substrates. J Am Chem Soc 2011; 133:15139-47. [PMID: 21894909 PMCID: PMC3189496 DOI: 10.1021/ja2055098] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Methods for synthetically manipulating protein structure enable greater flexibility in the study of protein function. Previous characterization of the Escherichia coli aminoacyl tRNA transferase (AaT) has shown that it can modify the N-terminus of a protein with an amino acid from a tRNA or a synthetic oligonucleotide donor. Here, we demonstrate that AaT can efficiently use a minimal adenosine substrate, which can be synthesized in one to two steps from readily available starting materials. We have characterized the enzymatic activity of AaT with aminoacyl adenosyl donors and found that reaction products do not inhibit AaT. The use of adenosyl donors removes the substrate limitations imposed by the use of synthetases for tRNA charging and avoids the complex synthesis of an oligonucleotide donor. Thus, our AaT donors increase the potential substrate scope and reaction scale for N-terminal protein modification under conditions that maintain folding.
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Affiliation(s)
- Anne M. Wagner
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323 USA
| | - Mark W. Fegley
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323 USA
| | - John B. Warner
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323 USA
| | - Christina L. J. Grindley
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323 USA
| | | | - E. James Petersson
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323 USA
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Fung AW, Ebhardt HA, Abeysundara H, Moore J, Xu Z, Fahlman RP. An alternative mechanism for the catalysis of peptide bond formation by L/F transferase: substrate binding and orientation. J Mol Biol 2011; 409:617-29. [PMID: 21530538 DOI: 10.1016/j.jmb.2011.04.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 04/05/2011] [Accepted: 04/11/2011] [Indexed: 10/18/2022]
Abstract
Eubacterial leucyl/phenylalanyl tRNA protein transferase (L/F transferase) catalyzes the transfer of a leucine or a phenylalanine from an aminoacyl-tRNA to the N-terminus of a protein substrate. This N-terminal addition of an amino acid is analogous to that of peptide synthesis by ribosomes. A previously proposed catalytic mechanism for Escherichia coli L/F transferase identified the conserved aspartate 186 (D186) and glutamine 188 (Q188) as key catalytic residues. We have reassessed the role of D186 and Q188 by investigating the enzymatic reactions and kinetics of enzymes possessing mutations to these active-site residues. Additionally three other amino acids proposed to be involved in aminoacyl-tRNA substrate binding are investigated for comparison. By quantitatively measuring product formation using a quantitative matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based assay, our results clearly demonstrate that, despite significant reduction in enzymatic activity as a result of different point mutations introduced into the active site of L/F transferase, the formation of product is still observed upon extended incubations. Our kinetic data and existing X-ray crystal structures result in a proposal that the critical roles of D186 and Q188, like the other amino acids in the active site, are for substrate binding and orientation and do not directly participate in the chemistry of peptide bond formation. Overall, we propose that L/F transferase does not directly participate in the chemistry of peptide bond formation but catalyzes the reaction by binding and orientating the substrates for reaction in an analogous mechanism that has been described for ribosomes.
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Affiliation(s)
- Angela W Fung
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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