51
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Hoernes TP, Faserl K, Juen MA, Kremser J, Gasser C, Fuchs E, Shi X, Siewert A, Lindner H, Kreutz C, Micura R, Joseph S, Höbartner C, Westhof E, Hüttenhofer A, Erlacher MD. Translation of non-standard codon nucleotides reveals minimal requirements for codon-anticodon interactions. Nat Commun 2018; 9:4865. [PMID: 30451861 PMCID: PMC6242847 DOI: 10.1038/s41467-018-07321-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/25/2018] [Indexed: 01/16/2023] Open
Abstract
The precise interplay between the mRNA codon and the tRNA anticodon is crucial for ensuring efficient and accurate translation by the ribosome. The insertion of RNA nucleobase derivatives in the mRNA allowed us to modulate the stability of the codon-anticodon interaction in the decoding site of bacterial and eukaryotic ribosomes, allowing an in-depth analysis of codon recognition. We found the hydrogen bond between the N1 of purines and the N3 of pyrimidines to be sufficient for decoding of the first two codon nucleotides, whereas adequate stacking between the RNA bases is critical at the wobble position. Inosine, found in eukaryotic mRNAs, is an important example of destabilization of the codon-anticodon interaction. Whereas single inosines are efficiently translated, multiple inosines, e.g., in the serotonin receptor 5-HT2C mRNA, inhibit translation. Thus, our results indicate that despite the robustness of the decoding process, its tolerance toward the weakening of codon-anticodon interactions is limited.
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Affiliation(s)
- Thomas Philipp Hoernes
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Klaus Faserl
- Division of Clinical Biochemistry, Biocenter, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Michael Andreas Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020, Innsbruck, Austria
| | - Johannes Kremser
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020, Innsbruck, Austria
| | - Catherina Gasser
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020, Innsbruck, Austria
| | - Elisabeth Fuchs
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020, Innsbruck, Austria
| | - Xinying Shi
- Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0314, USA
| | - Aaron Siewert
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Herbert Lindner
- Division of Clinical Biochemistry, Biocenter, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020, Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020, Innsbruck, Austria
| | - Simpson Joseph
- Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0314, USA
| | - Claudia Höbartner
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Eric Westhof
- Architecture and Reactivity of RNA, Institute of Molecular and Cellular Biology of the CNRS UPR9002/University of Strasbourg, Strasbourg, 67084, France
| | - Alexander Hüttenhofer
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Matthias David Erlacher
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, 6020, Innsbruck, Austria.
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52
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Wong HE, Huang CJ, Zhang Z. Amino Acid Misincorporation Propensities Revealed through Systematic Amino Acid Starvation. Biochemistry 2018; 57:6767-6779. [DOI: 10.1021/acs.biochem.8b00976] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- H. Edward Wong
- Process Development, Amgen, Inc., 1 Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Chung-Jr Huang
- Process Development, Amgen, Inc., 1 Amgen Center Drive, Thousand Oaks, California 91320, United States
| | - Zhongqi Zhang
- Process Development, Amgen, Inc., 1 Amgen Center Drive, Thousand Oaks, California 91320, United States
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53
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Joshi K, Bhatt MJ, Farabaugh PJ. Codon-specific effects of tRNA anticodon loop modifications on translational misreading errors in the yeast Saccharomyces cerevisiae. Nucleic Acids Res 2018; 46:10331-10339. [PMID: 30060218 PMCID: PMC6212777 DOI: 10.1093/nar/gky664] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 07/03/2018] [Accepted: 07/12/2018] [Indexed: 01/10/2023] Open
Abstract
Protein synthesis requires both high speed and accuracy to ensure a healthy cellular environment. Estimates of errors during protein synthesis in Saccharomyces cerevisiae have varied from 10-3 to 10-4 errors per codon. Here, we show that errors made by ${\rm{tRNA}}^{\rm Glu}_{\rm UUC}$ in yeast can vary 100-fold, from 10-6 to 10-4 errors per codon. The most frequent errors require a G•U mismatch at the second position for the near cognate codon GGA (Gly). We also show, contrary to our previous results, that yeast tRNAs can make errors involving mismatches at the wobble position but with low efficiency. We have also assessed the effect on misreading frequency of post-transcriptional modifications of tRNAs, which are known to regulate cognate codon decoding in yeast. We tested the roles of mcm5s2U34 and t6A37 and show that their effects depend on details of the codon anticodon interaction including the position of the modification with respect to the base mismatch and the nature of that mismatch. Both mcm5 and s2 modification of wobble uridine strongly stabilizes G2•U35 mismatches when ${\rm{tRNA}}^{\rm Glu}_{\rm UUC}$ misreads the GGA Gly codon but has weaker effects on other mismatches. By contrast, t6A37 destabilizes U1•U36 mismatches when ${\rm{tRNA}}^{\rm Lys}_{\rm UUU}$ misreads UAA or UAG but stabilizes mismatches at the second and wobble positions.
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Affiliation(s)
- Kartikeya Joshi
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Monika J Bhatt
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Philip J Farabaugh
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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54
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Hori H, Kawamura T, Awai T, Ochi A, Yamagami R, Tomikawa C, Hirata A. Transfer RNA Modification Enzymes from Thermophiles and Their Modified Nucleosides in tRNA. Microorganisms 2018; 6:E110. [PMID: 30347855 PMCID: PMC6313347 DOI: 10.3390/microorganisms6040110] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/17/2018] [Accepted: 10/17/2018] [Indexed: 12/11/2022] Open
Abstract
To date, numerous modified nucleosides in tRNA as well as tRNA modification enzymes have been identified not only in thermophiles but also in mesophiles. Because most modified nucleosides in tRNA from thermophiles are common to those in tRNA from mesophiles, they are considered to work essentially in steps of protein synthesis at high temperatures. At high temperatures, the structure of unmodified tRNA will be disrupted. Therefore, thermophiles must possess strategies to stabilize tRNA structures. To this end, several thermophile-specific modified nucleosides in tRNA have been identified. Other factors such as RNA-binding proteins and polyamines contribute to the stability of tRNA at high temperatures. Thermus thermophilus, which is an extreme-thermophilic eubacterium, can adapt its protein synthesis system in response to temperature changes via the network of modified nucleosides in tRNA and tRNA modification enzymes. Notably, tRNA modification enzymes from thermophiles are very stable. Therefore, they have been utilized for biochemical and structural studies. In the future, thermostable tRNA modification enzymes may be useful as biotechnology tools and may be utilized for medical science.
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Affiliation(s)
- Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Takuya Kawamura
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Takako Awai
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Anna Ochi
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Ryota Yamagami
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Chie Tomikawa
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Akira Hirata
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
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55
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Rozov A, Wolff P, Grosjean H, Yusupov M, Yusupova G, Westhof E. Tautomeric G•U pairs within the molecular ribosomal grip and fidelity of decoding in bacteria. Nucleic Acids Res 2018; 46:7425-7435. [PMID: 29931292 PMCID: PMC6101523 DOI: 10.1093/nar/gky547] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 05/27/2018] [Accepted: 06/06/2018] [Indexed: 11/14/2022] Open
Abstract
We report new crystallographic structures of Thermus thermophilus ribosomes complexed with long mRNAs and native Escherichia coli tRNAs. They complete the full set of combinations of Watson-Crick G•C and miscoding G•U pairs at the first two positions of the codon-anticodon duplex in ribosome functional complexes. Within the tight decoding center, miscoding G•U pairs occur, in all combinations, with a non-wobble geometry structurally indistinguishable from classical coding Watson-Crick pairs at the same first two positions. The contacts with the ribosomal grip surrounding the decoding center are all quasi-identical, except in the crowded environment of the amino group of a guanosine at the second position; in which case a G in the codons may be preferred. In vivo experimental data show that the translational errors due to miscoding by G•U pairs at the first two positions are the most frequently encountered ones, especially at the second position and with a G on the codon. Such preferred miscodings involve a switch from an A-U to a G•U pair in the tRNA/mRNA complex and very rarely from a G = C to a G•U pair. It is concluded that the frequencies of such occurrences are only weakly affected by the codon/anticodon structures but depend mainly on the stability and lifetime of the complex, the modifications present in the anticodon loop, especially those at positions 34 and 37, in addition to the relative concentration of cognate/near-cognate tRNA species present in the cellular tRNA pool.
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Affiliation(s)
- Alexey Rozov
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, INSERM, U964, CNRS/University of Strasbourg, UMR7104, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Philippe Wolff
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR9002, F-67084, Strasbourg, France
| | - Henri Grosjean
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR9002, F-67084, Strasbourg, France
| | - Marat Yusupov
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, INSERM, U964, CNRS/University of Strasbourg, UMR7104, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Gulnara Yusupova
- Department of Integrated Structural Biology, Institute of Genetics and Molecular and Cellular Biology, INSERM, U964, CNRS/University of Strasbourg, UMR7104, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Eric Westhof
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR9002, F-67084, Strasbourg, France
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56
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Yamagami R, Miyake R, Fukumoto A, Nakashima M, Hori H. Consumption of N5, N10-methylenetetrahydrofolate in Thermus thermophilus under nutrient-poor condition. J Biochem 2018. [PMID: 29538705 DOI: 10.1093/jb/mvy037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
TrmFO catalyzes the formation of 5-methyluridine at position 54 in tRNA and uses N5, N10-methylenetetrahydrofolate (CH2THF) as the methyl group donor. We found that the trmFO gene-disruptant strain of Thermus thermophilus, an extremely thermophilic eubacterium, can grow faster than the wild-type strain in the synthetic medium at 70°C (optimal growth temperature). Nucleoside analysis revealed that the majority of modifications were appropriately introduced into tRNA, showing that the limited nutrients are preferentially consumed in the tRNA modification systems. CH2THF is consumed not only for tRNA methylation by TrmFO but also for dTMP synthesis by ThyX and methionine synthesis by multiple steps including MetF reaction. In vivo experiment revealed that methylene group derived from serine was rapidly incorporated into DNA in the absence of TrmFO. Furthermore, the addition of thymidine to the medium accelerated growth speed of the wild-type strain. Moreover, in vitro experiments showed that TrmFO interfered with ThyX through consumption of CH2THF. Addition of methionine to the medium accelerated growth speed of wild-type strain and the activity of TrmFO was disturbed by MetF. Thus, the consumption of CH2THF by TrmFO has a negative effect on dTMP and methionine syntheses and results in the slow growth under a nutrient-poor condition.
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Affiliation(s)
- Ryota Yamagami
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Ryota Miyake
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Ayaka Fukumoto
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Misa Nakashima
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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57
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Uhlenbeck OC, Schrader JM. Evolutionary tuning impacts the design of bacterial tRNAs for the incorporation of unnatural amino acids by ribosomes. Curr Opin Chem Biol 2018; 46:138-145. [PMID: 30059836 DOI: 10.1016/j.cbpa.2018.07.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 04/27/2018] [Accepted: 07/13/2018] [Indexed: 01/23/2023]
Abstract
In order to function on the ribosome with uniform rate and adequate accuracy, each bacterial tRNA has evolved to have a characteristic sequence and set of modifications that compensate for the differing physical properties of its esterified amino acid and its codon-anticodon interaction. The sequence of the T-stem of each tRNA compensates for the differential effect of the esterified amino acid on the binding and release of EF-Tu during decoding. The sequence and modifications in the anticodon loop and core of tRNA impact the codon-anticodon strength and the ability of the tRNA to bend during codon recognition. These discoveries impact the design of tRNAs for the efficient and accurate incorporation of unnatural amino acids into proteins using bacterial translation systems.
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Affiliation(s)
- Olke C Uhlenbeck
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Jared M Schrader
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
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58
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Abstract
Protein translation is a key cellular process in which each codon of mRNAs has to be accurately and efficiently recognized by cognate tRNAs of a large repertoire of noncognate tRNAs. A successful decoding process is largely dependent on the presence of modified nucleotides within the anticodon loop, especially of tRNAs having to read A/U-rich codons. In this latter case, their roles appear to stabilize the codon–anticodon interaction, allowing them to reach an optimal energetic value close to that of other interacting tRNAs involving G/C-rich anticodons. In this work we demonstrate that, while helping an efficient translation of A/U-rich codons, modified nucleotides also allow certain unconventional base pairing to occur, as evidenced in the case of stop codon suppression. Some codons of the genetic code can be read not only by cognate, but also by near-cognate tRNAs. This flexibility is thought to be conferred mainly by a mismatch between the third base of the codon and the first of the anticodon (the so-called “wobble” position). However, this simplistic explanation underestimates the importance of nucleotide modifications in the decoding process. Using a system in which only near-cognate tRNAs can decode a specific codon, we investigated the role of six modifications of the anticodon, or adjacent nucleotides, of the tRNAs specific for Tyr, Gln, Lys, Trp, Cys, and Arg in Saccharomyces cerevisiae. Modifications almost systematically rendered these tRNAs able to act as near-cognate tRNAs at stop codons, even though they involve noncanonical base pairs, without markedly affecting their ability to decode cognate or near-cognate sense codons. These findings reveal an important effect of modifications to tRNA decoding with implications for understanding the flexibility of the genetic code.
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59
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60
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Kapur M, Ackerman SL. mRNA Translation Gone Awry: Translation Fidelity and Neurological Disease. Trends Genet 2018; 34:218-231. [PMID: 29352613 DOI: 10.1016/j.tig.2017.12.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 10/18/2022]
Abstract
Errors during mRNA translation can lead to a reduction in the levels of functional proteins and an increase in deleterious molecules. Advances in next-generation sequencing have led to the discovery of rare genetic disorders, many caused by mutations in genes encoding the mRNA translation machinery, as well as to a better understanding of translational dynamics through ribosome profiling. We discuss here multiple neurological disorders that are linked to errors in tRNA aminoacylation and ribosome decoding. We draw on studies from genetic models, including yeast and mice, to enhance our understanding of the translational defects observed in these diseases. Finally, we emphasize the importance of tRNA, their associated enzymes, and the inextricable link between accuracy and efficiency in the maintenance of translational fidelity.
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Affiliation(s)
- Mridu Kapur
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Susan L Ackerman
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
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61
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von der Haar T, Leadsham JE, Sauvadet A, Tarrant D, Adam IS, Saromi K, Laun P, Rinnerthaler M, Breitenbach-Koller H, Breitenbach M, Tuite MF, Gourlay CW. The control of translational accuracy is a determinant of healthy ageing in yeast. Open Biol 2017; 7:rsob.160291. [PMID: 28100667 PMCID: PMC5303280 DOI: 10.1098/rsob.160291] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 12/08/2016] [Indexed: 12/18/2022] Open
Abstract
Life requires the maintenance of molecular function in the face of stochastic processes that tend to adversely affect macromolecular integrity. This is particularly relevant during ageing, as many cellular functions decline with age, including growth, mitochondrial function and energy metabolism. Protein synthesis must deliver functional proteins at all times, implying that the effects of protein synthesis errors like amino acid misincorporation and stop-codon read-through must be minimized during ageing. Here we show that loss of translational accuracy accelerates the loss of viability in stationary phase yeast. Since reduced translational accuracy also reduces the folding competence of at least some proteins, we hypothesize that negative interactions between translational errors and age-related protein damage together overwhelm the cellular chaperone network. We further show that multiple cellular signalling networks control basal error rates in yeast cells, including a ROS signal controlled by mitochondrial activity, and the Ras pathway. Together, our findings indicate that signalling pathways regulating growth, protein homeostasis and energy metabolism may jointly safeguard accurate protein synthesis during healthy ageing.
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Affiliation(s)
- Tobias von der Haar
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Jane E Leadsham
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Aimie Sauvadet
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Daniel Tarrant
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Ilectra S Adam
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Kofo Saromi
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Peter Laun
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasser 34, 5020 Salzburg, Austria
| | - Mark Rinnerthaler
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasser 34, 5020 Salzburg, Austria
| | | | - Michael Breitenbach
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasser 34, 5020 Salzburg, Austria
| | - Mick F Tuite
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Campbell W Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
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62
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Dewe JM, Fuller BL, Lentini JM, Kellner SM, Fu D. TRMT1-Catalyzed tRNA Modifications Are Required for Redox Homeostasis To Ensure Proper Cellular Proliferation and Oxidative Stress Survival. Mol Cell Biol 2017; 37:e00214-17. [PMID: 28784718 PMCID: PMC5640816 DOI: 10.1128/mcb.00214-17] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 05/17/2017] [Accepted: 07/29/2017] [Indexed: 02/07/2023] Open
Abstract
Mutations in the tRNA methyltransferase 1 (TRMT1) gene have been identified as the cause of certain forms of autosomal-recessive intellectual disability (ID). However, the molecular pathology underlying ID-associated TRMT1 mutations is unknown, since the biological role of the encoded TRMT1 protein remains to be determined. Here, we have elucidated the molecular targets and function of TRMT1 to uncover the cellular effects of ID-causing TRMT1 mutations. Using human cells that have been rendered deficient in TRMT1, we show that TRMT1 is responsible for catalyzing the dimethylguanosine (m2,2G) base modification in both nucleus- and mitochondrion-encoded tRNAs. TRMT1-deficient cells exhibit decreased proliferation rates, alterations in global protein synthesis, and perturbations in redox homeostasis, including increased endogenous ROS levels and hypersensitivity to oxidizing agents. Notably, ID-causing TRMT1 variants are unable to catalyze the formation of m2,2G due to defects in RNA binding and cannot rescue oxidative stress sensitivity. Our results uncover a biological role for TRMT1-catalyzed tRNA modification in redox metabolism and show that individuals with TRMT1-associated ID are likely to have major perturbations in cellular homeostasis due to the lack of m2,2G modifications.
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Affiliation(s)
- Joshua M Dewe
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
| | - Benjamin L Fuller
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
| | - Jenna M Lentini
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
| | | | - Dragony Fu
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
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63
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Bednářová A, Hanna M, Durham I, VanCleave T, England A, Chaudhuri A, Krishnan N. Lost in Translation: Defects in Transfer RNA Modifications and Neurological Disorders. Front Mol Neurosci 2017; 10:135. [PMID: 28536502 PMCID: PMC5422465 DOI: 10.3389/fnmol.2017.00135] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/20/2017] [Indexed: 11/13/2022] Open
Abstract
Transfer RNAs (tRNAs) are key molecules participating in protein synthesis. To augment their functionality they undergo extensive post-transcriptional modifications and, as such, are subject to regulation at multiple levels including transcription, transcript processing, localization and ribonucleoside base modification. Post-transcriptional enzyme-catalyzed modification of tRNA occurs at a number of base and sugar positions and influences specific anticodon-codon interactions and regulates translation, its efficiency and fidelity. This phenomenon of nucleoside modification is most remarkable and results in a rich structural diversity of tRNA of which over 100 modified nucleosides have been characterized. Most often these hypermodified nucleosides are found in the wobble position of tRNAs, where they play a direct role in codon recognition as well as in maintaining translational efficiency and fidelity, etc. Several recent studies have pointed to a link between defects in tRNA modifications and human diseases including neurological disorders. Therefore, defects in tRNA modifications in humans need intensive characterization at the enzymatic and mechanistic level in order to pave the way to understand how lack of such modifications are associated with neurological disorders with the ultimate goal of gaining insights into therapeutic interventions.
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Affiliation(s)
- Andrea Bednářová
- Department of Biochemistry and Physiology, Institute of Entomology, Biology Centre, Academy of SciencesČeské Budějovice, Czechia.,Laboratory of Molecular Biology and Biochemistry, Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State UniversityMississippi State, MS, USA
| | - Marley Hanna
- Molecular Biosciences Program, Arkansas State UniversityJonesboro, AR, USA
| | - Isabella Durham
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State UniversityMississippi State, MS, USA
| | - Tara VanCleave
- Laboratory of Molecular Biology and Biochemistry, Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State UniversityMississippi State, MS, USA
| | - Alexis England
- Laboratory of Molecular Biology and Biochemistry, Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State UniversityMississippi State, MS, USA
| | | | - Natraj Krishnan
- Laboratory of Molecular Biology and Biochemistry, Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State UniversityMississippi State, MS, USA
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64
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Agris PF, Narendran A, Sarachan K, Väre VYP, Eruysal E. The Importance of Being Modified: The Role of RNA Modifications in Translational Fidelity. Enzymes 2017; 41:1-50. [PMID: 28601219 DOI: 10.1016/bs.enz.2017.03.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The posttranscriptional modifications of tRNA's anticodon stem and loop (ASL) domain represent a third level, a third code, to the accuracy and efficiency of translating mRNA codons into the correct amino acid sequence of proteins. Modifications of tRNA's ASL domain are enzymatically synthesized and site specifically located at the anticodon wobble position-34 and 3'-adjacent to the anticodon at position-37. Degeneracy of the 64 Universal Genetic Codes and the limitation in the number of tRNA species require some tRNAs to decode more than one codon. The specific modification chemistries and their impact on the tRNA's ASL structure and dynamics enable one tRNA to decode cognate and "wobble codons" or to expand recognition to synonymous codons, all the while maintaining the translational reading frame. Some modified nucleosides' chemistries prestructure tRNA to read the two codons of a specific amino acid that shares a twofold degenerate codon box, and other chemistries allow a different tRNA to respond to all four codons of a fourfold degenerate codon box. Thus, tRNA ASL modifications are critical and mutations in genes for the modification enzymes and tRNA, the consequences of which is a lack of modification, lead to mistranslation and human disease. By optimizing tRNA anticodon chemistries, structure, and dynamics in all organisms, modifications ensure translational fidelity of mRNA transcripts.
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Affiliation(s)
- Paul F Agris
- The RNA Institute, State University of New York, Albany, NY, United States.
| | - Amithi Narendran
- The RNA Institute, State University of New York, Albany, NY, United States
| | - Kathryn Sarachan
- The RNA Institute, State University of New York, Albany, NY, United States
| | - Ville Y P Väre
- The RNA Institute, State University of New York, Albany, NY, United States
| | - Emily Eruysal
- The RNA Institute, State University of New York, Albany, NY, United States
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Nilsson K, Jäger G, Björk GR. An unmodified wobble uridine in tRNAs specific for Glutamine, Lysine, and Glutamic acid from Salmonella enterica Serovar Typhimurium results in nonviability-Due to increased missense errors? PLoS One 2017; 12:e0175092. [PMID: 28430781 PMCID: PMC5400242 DOI: 10.1371/journal.pone.0175092] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/20/2017] [Indexed: 11/18/2022] Open
Abstract
In the wobble position of tRNAs specific for Gln, Lys, and Glu a universally conserved 5-methylene-2-thiouridine derivative (xm5s2U34, x denotes any of several chemical substituents and 34 denotes the wobble position) is present, which is 5-(carboxy)methylaminomethyl-2-thiouridine ((c)mnm5s2U34) in Bacteria and 5-methylcarboxymethyl-2-thiouridine (mcm5s2U34) in Eukarya. Here we show that mutants of the bacterium Salmonella enterica Serovar Typhimurium LT2 lacking either the s2- or the (c)mnm5-group of (c)mnm5s2U34 grow poorly especially at low temperature and do not grow at all at 15°C in both rich and glucose minimal media. A double mutant of S. enterica lacking both the s2- and the (c)mnm5-groups, and that thus has an unmodified uridine as wobble nucleoside, is nonviable at different temperatures. Overexpression of [Formula: see text] lacking either the s2- or the (c)mnm5-group and of [Formula: see text] lacking the s2-group exaggerated the reduced growth induced by the modification deficiency, whereas overexpression of [Formula: see text] lacking the mnm5-group did not. From these results we suggest that the primary function of cmnm5s2U34 in bacterial [Formula: see text] and mnm5s2U34 in [Formula: see text] is to prevent missense errors, but the mnm5-group of [Formula: see text] does not. However, other translational errors causing the growth defect cannot be excluded. These results are in contrast to what is found in yeast, since overexpression of the corresponding hypomodified yeast tRNAs instead counteracts the modification deficient induced phenotypes. Accordingly, it was suggested that the primary function of mcm5s2U34 in these yeast tRNAs is to improve cognate codon reading rather than prevents missense errors. Thus, although the xm5s2U34 derivatives are universally conserved, their major functional impact on bacterial and eukaryotic tRNAs may be different.
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Affiliation(s)
| | - Gunilla Jäger
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Glenn R. Björk
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- * E-mail:
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66
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Väre VYP, Eruysal ER, Narendran A, Sarachan KL, Agris PF. Chemical and Conformational Diversity of Modified Nucleosides Affects tRNA Structure and Function. Biomolecules 2017; 7:E29. [PMID: 28300792 PMCID: PMC5372741 DOI: 10.3390/biom7010029] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/06/2017] [Accepted: 03/06/2017] [Indexed: 12/21/2022] Open
Abstract
RNAs are central to all gene expression through the control of protein synthesis. Four major nucleosides, adenosine, guanosine, cytidine and uridine, compose RNAs and provide sequence variation, but are limited in contributions to structural variation as well as distinct chemical properties. The ability of RNAs to play multiple roles in cellular metabolism is made possible by extensive variation in length, conformational dynamics, and the over 100 post-transcriptional modifications. There are several reviews of the biochemical pathways leading to RNA modification, but the physicochemical nature of modified nucleosides and how they facilitate RNA function is of keen interest, particularly with regard to the contributions of modified nucleosides. Transfer RNAs (tRNAs) are the most extensively modified RNAs. The diversity of modifications provide versatility to the chemical and structural environments. The added chemistry, conformation and dynamics of modified nucleosides occurring at the termini of stems in tRNA's cloverleaf secondary structure affect the global three-dimensional conformation, produce unique recognition determinants for macromolecules to recognize tRNAs, and affect the accurate and efficient decoding ability of tRNAs. This review will discuss the impact of specific chemical moieties on the structure, stability, electrochemical properties, and function of tRNAs.
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Affiliation(s)
- Ville Y P Väre
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA.
| | - Emily R Eruysal
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA.
| | - Amithi Narendran
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA.
| | - Kathryn L Sarachan
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA.
| | - Paul F Agris
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA.
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Mapping Post-Transcriptional Modifications onto Transfer Ribonucleic Acid Sequences by Liquid Chromatography Tandem Mass Spectrometry. Biomolecules 2017; 7:biom7010021. [PMID: 28241457 PMCID: PMC5372733 DOI: 10.3390/biom7010021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 02/15/2017] [Indexed: 01/07/2023] Open
Abstract
Liquid chromatography, coupled with tandem mass spectrometry, has become one of the most popular methods for the analysis of post-transcriptionally modified transfer ribonucleic acids (tRNAs). Given that the information collected using this platform is entirely determined by the mass of the analyte, it has proven to be the gold standard for accurately assigning nucleobases to the sequence. For the past few decades many labs have worked to improve the analysis, contiguous to instrumentation manufacturers developing faster and more sensitive instruments. With biological discoveries relating to ribonucleic acid happening more frequently, mass spectrometry has been invaluable in helping to understand what is happening at the molecular level. Here we present a brief overview of the methods that have been developed and refined for the analysis of modified tRNAs by liquid chromatography tandem mass spectrometry.
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Cross-Talk between Dnmt2-Dependent tRNA Methylation and Queuosine Modification. Biomolecules 2017; 7:biom7010014. [PMID: 28208632 PMCID: PMC5372726 DOI: 10.3390/biom7010014] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/02/2017] [Accepted: 02/02/2017] [Indexed: 12/22/2022] Open
Abstract
Enzymes of the Dnmt2 family of methyltransferases have yielded a number of unexpected discoveries. The first surprise came more than ten years ago when it was realized that, rather than being DNA methyltransferases, Dnmt2 enzymes actually are transfer RNA (tRNA) methyltransferases for cytosine-5 methylation, foremost C38 (m5C38) of tRNAAsp. The second unanticipated finding was our recent discovery of a nutritional regulation of Dnmt2 in the fission yeast Schizosaccharomyces pombe. Significantly, the presence of the nucleotide queuosine in tRNAAsp strongly stimulates Dnmt2 activity both in vivo and in vitro in S. pombe. Queuine, the respective base, is a hypermodified guanine analog that is synthesized from guanosine-5’-triphosphate (GTP) by bacteria. Interestingly, most eukaryotes have queuosine in their tRNA. However, they cannot synthesize it themselves, but rather salvage it from food or from gut microbes. The queuine obtained from these sources comes from the breakdown of tRNAs, where the queuine ultimately was synthesized by bacteria. Queuine thus has been termed a micronutrient. This review summarizes the current knowledge of Dnmt2 methylation and queuosine modification with respect to translation as well as the organismal consequences of the absence of these modifications. Models for the functional cooperation between these modifications and its wider implications are discussed.
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69
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Zallot R, Yuan Y, de Crécy-Lagard V. The Escherichia coli COG1738 Member YhhQ Is Involved in 7-Cyanodeazaguanine (preQ₀) Transport. Biomolecules 2017; 7:E12. [PMID: 28208705 PMCID: PMC5372724 DOI: 10.3390/biom7010012] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 11/17/2022] Open
Abstract
Queuosine (Q) is a complex modification of the wobble base in tRNAs with GUN anticodons. The full Q biosynthesis pathway has been elucidated in Escherichia coli. FolE, QueD, QueE and QueC are involved in the conversion of guanosine triphosphate (GTP) to 7-cyano-7-deazaguanine (preQ₀), an intermediate of increasing interest for its central role in tRNA and DNA modification and secondary metabolism. QueF then reduces preQ₀ to 7-aminomethyl-7-deazaguanine (preQ₁). PreQ₁ is inserted into tRNAs by tRNA guanine(34) transglycosylase (TGT). The inserted base preQ₁ is finally matured to Q by two additional steps involving QueA and QueG or QueH. Most Eubacteria harbor the full set of Q synthesis genes and are predicted to synthesize Q de novo. However, some bacteria only encode enzymes involved in the second half of the pathway downstream of preQ₀ synthesis, including the signature enzyme TGT. Different patterns of distribution of the queF, tgt, queA and queG or queH genes are observed, suggesting preQ₀, preQ₁ or even the queuine base being salvaged in specific organisms. Such salvage pathways require the existence of specific 7-deazapurine transporters that have yet to be identified. The COG1738 family was identified as a candidate for a missing preQ₀/preQ₁ transporter in prokaryotes, by comparative genomics analyses. The existence of Q precursor salvage was confirmed for the first time in bacteria, in vivo, through an indirect assay. The involvement of the COG1738 in salvage of a Q precursor was experimentally validated in Escherichia coli, where it was shown that the COG1738 family member YhhQ is essential for preQ₀ transport.
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Affiliation(s)
- Rémi Zallot
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
| | - Yifeng Yuan
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
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Hutinet G, Swarjo MA, de Crécy-Lagard V. Deazaguanine derivatives, examples of crosstalk between RNA and DNA modification pathways. RNA Biol 2016; 14:1175-1184. [PMID: 27937735 PMCID: PMC5699537 DOI: 10.1080/15476286.2016.1265200] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Seven-deazapurine modifications were thought to be highly specific of tRNAs, but have now been discovered in DNA of phages and of phylogenetically diverse bacteria, illustrating the plasticity of these modification pathways. The intermediate 7-cyano-7-deazaguanine (preQ0) is a shared precursor in the pathways leading to the insetion of 7-deazapurine derivatives in both tRNA and DNA. It is also used as an intermediate in the synthesis of secondary metabolites such as toyocamacin. The presence of 7-deazapurine in DNA is proposed to be a protection mechanism against endonucleases. This makes preQ0 a metabolite of underappreaciated but central importance.
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Affiliation(s)
- Geoffrey Hutinet
- a Department of Microbiology and Cell Science , University of Florida , Gainesville , FL , USA
| | - Manal A Swarjo
- b Department of Chemistry and Biochemistry , San Diego State University , San Diego , CA , USA
| | - Valérie de Crécy-Lagard
- a Department of Microbiology and Cell Science , University of Florida , Gainesville , FL , USA
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71
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Biddle W, Schmitt MA, Fisk JD. Modification of orthogonal tRNAs: unexpected consequences for sense codon reassignment. Nucleic Acids Res 2016; 44:10042-10050. [PMID: 27915288 PMCID: PMC5137457 DOI: 10.1093/nar/gkw948] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/05/2016] [Accepted: 10/10/2016] [Indexed: 12/25/2022] Open
Abstract
Breaking the degeneracy of the genetic code via sense codon reassignment has emerged as a way to incorporate multiple copies of multiple non-canonical amino acids into a protein of interest. Here, we report the modification of a normally orthogonal tRNA by a host enzyme and show that this adventitious modification has a direct impact on the activity of the orthogonal tRNA in translation. We observed nearly equal decoding of both histidine codons, CAU and CAC, by an engineered orthogonal M. jannaschii tRNA with an AUG anticodon: tRNAOpt. We suspected a modification of the tRNAOptAUG anticodon was responsible for the anomalous lack of codon discrimination and demonstrate that adenosine 34 of tRNAOptAUG is converted to inosine. We identified tRNAOptAUG anticodon loop variants that increase reassignment of the histidine CAU codon, decrease incorporation in response to the histidine CAC codon, and improve cell health and growth profiles. Recognizing tRNA modification as both a potential pitfall and avenue of directed alteration will be important as the field of genetic code engineering continues to infiltrate the genetic codes of diverse organisms.
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Affiliation(s)
- Wil Biddle
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | - Margaret A Schmitt
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - John D Fisk
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA .,Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA.,School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
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Grosjean H, Westhof E. An integrated, structure- and energy-based view of the genetic code. Nucleic Acids Res 2016; 44:8020-40. [PMID: 27448410 PMCID: PMC5041475 DOI: 10.1093/nar/gkw608] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 06/11/2016] [Accepted: 06/17/2016] [Indexed: 12/25/2022] Open
Abstract
The principles of mRNA decoding are conserved among all extant life forms. We present an integrative view of all the interaction networks between mRNA, tRNA and rRNA: the intrinsic stability of codon-anticodon duplex, the conformation of the anticodon hairpin, the presence of modified nucleotides, the occurrence of non-Watson-Crick pairs in the codon-anticodon helix and the interactions with bases of rRNA at the A-site decoding site. We derive a more information-rich, alternative representation of the genetic code, that is circular with an unsymmetrical distribution of codons leading to a clear segregation between GC-rich 4-codon boxes and AU-rich 2:2-codon and 3:1-codon boxes. All tRNA sequence variations can be visualized, within an internal structural and energy framework, for each organism, and each anticodon of the sense codons. The multiplicity and complexity of nucleotide modifications at positions 34 and 37 of the anticodon loop segregate meaningfully, and correlate well with the necessity to stabilize AU-rich codon-anticodon pairs and to avoid miscoding in split codon boxes. The evolution and expansion of the genetic code is viewed as being originally based on GC content with progressive introduction of A/U together with tRNA modifications. The representation we present should help the engineering of the genetic code to include non-natural amino acids.
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Affiliation(s)
- Henri Grosjean
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Eric Westhof
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de biologie moléculaire et cellulaire du CNRS, 15 rue René Descartes, 67084 Strasbourg, France
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73
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Duechler M, Leszczyńska G, Sochacka E, Nawrot B. Nucleoside modifications in the regulation of gene expression: focus on tRNA. Cell Mol Life Sci 2016; 73:3075-95. [PMID: 27094388 PMCID: PMC4951516 DOI: 10.1007/s00018-016-2217-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 01/10/2023]
Abstract
Both, DNA and RNA nucleoside modifications contribute to the complex multi-level regulation of gene expression. Modified bases in tRNAs modulate protein translation rates in a highly dynamic manner. Synonymous codons, which differ by the third nucleoside in the triplet but code for the same amino acid, may be utilized at different rates according to codon-anticodon affinity. Nucleoside modifications in the tRNA anticodon loop can favor the interaction with selected codons by stabilizing specific base pairs. Similarly, weakening of base pairing can discriminate against binding to near-cognate codons. mRNAs enriched in favored codons are translated in higher rates constituting a fine-tuning mechanism for protein synthesis. This so-called codon bias establishes a basic protein level, but sometimes it is necessary to further adjust the production rate of a particular protein to actual requirements, brought by, e.g., stages in circadian rhythms, cell cycle progression or exposure to stress. Such an adjustment is realized by the dynamic change of tRNA modifications resulting in the preferential translation of mRNAs coding for example for stress proteins to facilitate cell survival. Furthermore, tRNAs contribute in an entirely different way to another, less specific stress response consisting in modification-dependent tRNA cleavage that contributes to the general down-regulation of protein synthesis. In this review, we summarize control functions of nucleoside modifications in gene regulation with a focus on recent findings on protein synthesis control by tRNA base modifications.
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Affiliation(s)
- Markus Duechler
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland.
| | - Grażyna Leszczyńska
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Elzbieta Sochacka
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Barbara Nawrot
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
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Abstract
The expression of a gene is a tightly regulated process and is exerted by a myriad of different mechanisms. Recently, RNA modifications located in coding sequences of mRNAs, have been identified as potential regulators of gene expression. N6-methyladenosine (m6A), 5-methylcytosine (m5C), pseudouridine (Ψ) and N1-methyladenosine (m1A) have been found within open reading frames of mRNAs. The presence of these mRNA modifications has been implicated to modulate the fate of an mRNA, ranging from maturation to its translation and even degradation. However, many aspects concerning the biological functions of mRNA modifications remain elusive. Recently, systematic in vitro studies allowed a first glimpse of the direct interplay of mRNA modifications and the efficiency and fidelity of ribosomal translation. It thereby became evident that the effects of mRNA modifications were, astonishingly versatile, depending on the type, position or sequence context. The incorporation of a single modification could either prematurely terminate protein synthesis, reduce the peptide yield or alter the amino acid sequence identity. These results implicate that mRNA modifications are a powerful mechanism to post-transcriptionally regulate gene expression.
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Affiliation(s)
- Thomas Philipp Hoernes
- a Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck , Innsbruck , Austria
| | - Alexander Hüttenhofer
- a Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck , Innsbruck , Austria
| | - Matthias David Erlacher
- a Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck , Innsbruck , Austria
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