1
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Isaacson JR, Berg MD, Jagiello J, Yeung W, Charles B, Villén J, Brandl CJ, Moehring AJ. Mistranslating tRNA variants have anticodon- and sex-specific impacts on Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598535. [PMID: 38915589 PMCID: PMC11195196 DOI: 10.1101/2024.06.11.598535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Transfer RNAs (tRNAs) are vital in determining the specificity of translation. Mutations in tRNA genes can result in the misincorporation of amino acids into nascent polypeptides in a process known as mistranslation. Since mistranslation has different impacts, depending on the type of amino acid substitution, our goal here was to compare the impact of different mistranslating tRNASer variants on fly development, lifespan, and behaviour. We established two mistranslating fly lines, one with a tRNASer variant that misincorporates serine at valine codons (V→S) and the other that misincorporates serine at threonine codons (T→S). While both mistranslating tRNAs increased development time and developmental lethality, the severity of the impacts differed depending on amino acid substitution and sex. The V→S variant extended embryonic, larval, and pupal development whereas the T→S only extended larval and pupal development. Females, but not males, containing either mistranslating tRNA presented with significantly more anatomical deformities than controls. Mistranslating females also experienced extended lifespan whereas mistranslating male lifespan was unaffected. In addition, mistranslating flies from both sexes showed improved locomotion as they aged, suggesting delayed neurodegeneration. Therefore, although mistranslation causes detrimental effects, we demonstrate that mistranslation also has positive effects on complex traits such as lifespan and locomotion. This has important implications for human health given the prevalence of tRNA variants in humans.
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Affiliation(s)
| | - Matthew D. Berg
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98195
| | - Jessica Jagiello
- Department of Biology, Western University, N6A 5B7, London, Canada
| | - William Yeung
- Department of Biology, Western University, N6A 5B7, London, Canada
| | - Brendan Charles
- Department of Biology, Western University, N6A 5B7, London, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98195
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2
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Isaacson JR, Berg MD, Yeung W, Villén J, Brandl CJ, Moehring AJ. Impact of tRNA-induced proline-to-serine mistranslation on the transcriptome of Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593249. [PMID: 38766246 PMCID: PMC11100759 DOI: 10.1101/2024.05.08.593249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Mistranslation is the misincorporation of an amino acid into a polypeptide. Mistranslation has diverse effects on multicellular eukaryotes and is implicated in several human diseases. In Drosophila melanogaster, a serine transfer RNA (tRNA) that misincorporates serine at proline codons (P→S) affects male and female flies differently. The mechanisms behind this discrepancy are currently unknown. Here, we compare the transcriptional response of male and female flies to P→S mistranslation to identify genes and cellular processes that underlie sex-specific differences. Both males and females downregulate genes associated with various metabolic processes in response to P→S mistranslation. Males downregulate genes associated with extracellular matrix organization and response to negative stimuli such as wounding, whereas females downregulate aerobic respiration and ATP synthesis genes. Both sexes upregulate genes associated with gametogenesis, but females also upregulate cell cycle and DNA repair genes. These observed differences in the transcriptional response of male and female flies to P→S mistranslation have important implications for the sex-specific impact of mistranslation on disease and tRNA therapeutics.
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Affiliation(s)
| | - Matthew D. Berg
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98195
| | - William Yeung
- Department of Biology, Western University, N6A 5B7, London, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98195
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3
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Davey-Young J, Hasan F, Tennakoon R, Rozik P, Moore H, Hall P, Cozma E, Genereaux J, Hoffman KS, Chan PP, Lowe TM, Brandl CJ, O’Donoghue P. Mistranslating the genetic code with leucine in yeast and mammalian cells. RNA Biol 2024; 21:1-23. [PMID: 38629491 PMCID: PMC11028032 DOI: 10.1080/15476286.2024.2340297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2024] [Indexed: 04/19/2024] Open
Abstract
Translation fidelity relies on accurate aminoacylation of transfer RNAs (tRNAs) by aminoacyl-tRNA synthetases (AARSs). AARSs specific for alanine (Ala), leucine (Leu), serine, and pyrrolysine do not recognize the anticodon bases. Single nucleotide anticodon variants in their cognate tRNAs can lead to mistranslation. Human genomes include both rare and more common mistranslating tRNA variants. We investigated three rare human tRNALeu variants that mis-incorporate Leu at phenylalanine or tryptophan codons. Expression of each tRNALeu anticodon variant in neuroblastoma cells caused defects in fluorescent protein production without significantly increased cytotoxicity under normal conditions or in the context of proteasome inhibition. Using tRNA sequencing and mass spectrometry we confirmed that each tRNALeu variant was expressed and generated mistranslation with Leu. To probe the flexibility of the entire genetic code towards Leu mis-incorporation, we created 64 yeast strains to express all possible tRNALeu anticodon variants in a doxycycline-inducible system. While some variants showed mild or no growth defects, many anticodon variants, enriched with G/C at positions 35 and 36, including those replacing Leu for proline, arginine, alanine, or glycine, caused dramatic reductions in growth. Differential phenotypic defects were observed for tRNALeu mutants with synonymous anticodons and for different tRNALeu isoacceptors with the same anticodon. A comparison to tRNAAla anticodon variants demonstrates that Ala mis-incorporation is more tolerable than Leu at nearly every codon. The data show that the nature of the amino acid substitution, the tRNA gene, and the anticodon are each important factors that influence the ability of cells to tolerate mistranslating tRNAs.
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Affiliation(s)
- Josephine Davey-Young
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Farah Hasan
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Rasangi Tennakoon
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Peter Rozik
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Henry Moore
- Department of Biomolecular Engineering, Baskin School of Engineering & UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Peter Hall
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Ecaterina Cozma
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | | | - Patricia P. Chan
- Department of Biomolecular Engineering, Baskin School of Engineering & UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Todd M. Lowe
- Department of Biomolecular Engineering, Baskin School of Engineering & UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Christopher J. Brandl
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Patrick O’Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
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4
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Hasan F, Lant JT, O'Donoghue P. Perseverance of protein homeostasis despite mistranslation of glycine codons with alanine. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220029. [PMID: 36633285 PMCID: PMC9835607 DOI: 10.1098/rstb.2022.0029] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/05/2022] [Indexed: 01/13/2023] Open
Abstract
By linking amino acids to their codon assignments, transfer RNAs (tRNAs) are essential for protein synthesis and translation fidelity. Some human tRNA variants cause amino acid mis-incorporation at a codon or set of codons. We recently found that a naturally occurring tRNASer variant decodes phenylalanine codons with serine and inhibits protein synthesis. Here, we hypothesized that human tRNA variants that misread glycine (Gly) codons with alanine (Ala) will also disrupt protein homeostasis. The A3G mutation occurs naturally in tRNAGly variants (tRNAGlyCCC, tRNAGlyGCC) and creates an alanyl-tRNA synthetase (AlaRS) identity element (G3 : U70). Because AlaRS does not recognize the anticodon, the human tRNAAlaAGC G35C (tRNAAlaACC) variant may function similarly to mis-incorporate Ala at Gly codons. The tRNAGly and tRNAAla variants had no effect on protein synthesis in mammalian cells under normal growth conditions; however, tRNAGlyGCC A3G depressed protein synthesis in the context of proteasome inhibition. Mass spectrometry confirmed Ala mistranslation at multiple Gly codons caused by the tRNAGlyGCC A3G and tRNAAlaAGC G35C mutants, and in some cases, we observed multiple mistranslation events in the same peptide. The data reveal mistranslation of Ala at Gly codons and defects in protein homeostasis generated by natural human tRNA variants that are tolerated under normal conditions. This article is part of the theme issue 'Reactivity and mechanism in chemical and synthetic biology'.
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MESH Headings
- Humans
- Alanine/genetics
- Alanine/chemistry
- Alanine/metabolism
- Alanine-tRNA Ligase/chemistry
- Alanine-tRNA Ligase/genetics
- Alanine-tRNA Ligase/metabolism
- Codon/genetics
- Glycine/genetics
- Glycine/metabolism
- Protein Biosynthesis
- Proteostasis
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA, Transfer, Ala/chemistry
- RNA, Transfer, Ala/genetics
- RNA, Transfer, Ala/metabolism
- RNA, Transfer, Gly/metabolism
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Affiliation(s)
- Farah Hasan
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1
| | - Jeremy T. Lant
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1
| | - Patrick O'Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1
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5
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Cozma E, Rao M, Dusick M, Genereaux J, Rodriguez-Mias RA, Villén J, Brandl CJ, Berg MD. Anticodon sequence determines the impact of mistranslating tRNA Ala variants. RNA Biol 2023; 20:791-804. [PMID: 37776539 PMCID: PMC10543346 DOI: 10.1080/15476286.2023.2257471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2023] [Indexed: 10/02/2023] Open
Abstract
Transfer RNAs (tRNAs) maintain translation fidelity through accurate charging by their cognate aminoacyl-tRNA synthetase and codon:anticodon base pairing with the mRNA at the ribosome. Mistranslation occurs when an amino acid not specified by the genetic message is incorporated into proteins and has applications in biotechnology, therapeutics and is relevant to disease. Since the alanyl-tRNA synthetase uniquely recognizes a G3:U70 base pair in tRNAAla and the anticodon plays no role in charging, tRNAAla variants with anticodon mutations have the potential to mis-incorporate alanine. Here, we characterize the impact of the 60 non-alanine tRNAAla anticodon variants on the growth of Saccharomyces cerevisiae. Overall, 36 tRNAAla anticodon variants decreased growth in single- or multi-copy. Mass spectrometry analysis of the cellular proteome revealed that 52 of 57 anticodon variants, not decoding alanine or stop codons, induced mistranslation when on single-copy plasmids. Variants with G/C-rich anticodons resulted in larger growth deficits than A/U-rich variants. In most instances, synonymous anticodon variants impact growth differently, with anticodons containing U at base 34 being the least impactful. For anticodons generating the same amino acid substitution, reduced growth generally correlated with the abundance of detected mistranslation events. Differences in decoding specificity, even between synonymous anticodons, resulted in each tRNAAla variant mistranslating unique sets of peptides and proteins. We suggest that these differences in decoding specificity are also important in determining the impact of tRNAAla anticodon variants.
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Affiliation(s)
- Ecaterina Cozma
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Megha Rao
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Madison Dusick
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | | | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Christopher J. Brandl
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Matthew D. Berg
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
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6
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Berg MD, Zhu Y, Loll-Krippleber R, San Luis BJ, Genereaux J, Boone C, Villén J, Brown GW, Brandl CJ. Genetic background and mistranslation frequency determine the impact of mistranslating tRNASerUGG. G3 GENES|GENOMES|GENETICS 2022; 12:6588684. [PMID: 35587152 PMCID: PMC9258585 DOI: 10.1093/g3journal/jkac125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/07/2022] [Indexed: 12/02/2022]
Abstract
Transfer RNA variants increase the frequency of mistranslation, the misincorporation of an amino acid not specified by the “standard” genetic code, to frequencies approaching 10% in yeast and bacteria. Cells cope with these variants by having multiple copies of each tRNA isodecoder and through pathways that deal with proteotoxic stress. In this study, we define the genetic interactions of the gene encoding tRNASerUGG,G26A, which mistranslates serine at proline codons. Using a collection of yeast temperature-sensitive alleles, we identify negative synthetic genetic interactions between the mistranslating tRNA and 109 alleles representing 91 genes, with nearly half of the genes having roles in RNA processing or protein folding and turnover. By regulating tRNA expression, we then compare the strength of the negative genetic interaction for a subset of identified alleles under differing amounts of mistranslation. The frequency of mistranslation correlated with the impact on cell growth for all strains analyzed; however, there were notable differences in the extent of the synthetic interaction at different frequencies of mistranslation depending on the genetic background. For many of the strains, the extent of the negative interaction with tRNASerUGG,G26A was proportional to the frequency of mistranslation or only observed at intermediate or high frequencies. For others, the synthetic interaction was approximately equivalent at all frequencies of mistranslation. As humans contain similar mistranslating tRNAs, these results are important when analyzing the impact of tRNA variants on disease, where both the individual’s genetic background and the expression of the mistranslating tRNA variant need to be considered.
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Affiliation(s)
- Matthew D Berg
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
- Department of Genome Sciences, University of Washington , Seattle, WA 98195, USA
| | - Yanrui Zhu
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
| | - Raphaël Loll-Krippleber
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 3E1, Canada
| | - Bryan-Joseph San Luis
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 1A8, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
| | - Charles Boone
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 1A8, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington , Seattle, WA 98195, USA
| | - Grant W Brown
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 3E1, Canada
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
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7
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Isaacson JR, Berg MD, Charles B, Jagiello J, Villén J, Brandl CJ, Moehring AJ. A novel mistranslating tRNA model in Drosophila melanogaster has diverse, sexually dimorphic effects. G3 GENES|GENOMES|GENETICS 2022; 12:6526391. [PMID: 35143655 PMCID: PMC9073681 DOI: 10.1093/g3journal/jkac035] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/03/2022] [Indexed: 11/17/2022]
Abstract
Transfer RNAs (tRNAs) are the adaptor molecules required for reading the genetic code and producing proteins. Transfer RNA variants can lead to genome-wide mistranslation, the misincorporation of amino acids not specified by the standard genetic code into nascent proteins. While genome sequencing has identified putative mistranslating transfer RNA variants in human populations, little is known regarding how mistranslation affects multicellular organisms. Here, we create a multicellular model of mistranslation by integrating a serine transfer RNA variant that mistranslates serine for proline (tRNAUGG,G26ASer) into the Drosophila melanogaster genome. We confirm mistranslation via mass spectrometry and find that tRNAUGG,G26ASer misincorporates serine for proline at a frequency of ∼0.6% per codon. tRNAUGG,G26ASer extends development time and decreases the number of flies that reach adulthood. While both sexes of adult flies containing tRNAUGG,G26ASer present with morphological deformities and poor climbing performance, these effects are more pronounced in female flies and the impact on climbing performance is exacerbated by age. This model will enable studies into the synergistic effects of mistranslating transfer RNA variants and disease-causing alleles.
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Affiliation(s)
- Joshua R Isaacson
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Matthew D Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Brendan Charles
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Jessica Jagiello
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Amanda J Moehring
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
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8
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Rozik P, Szabla R, Lant JT, Kiri R, Wright DE, Junop M, O'Donoghue P. A novel fluorescent reporter sensitive to serine mis-incorporation. RNA Biol 2022; 19:221-233. [PMID: 35167412 PMCID: PMC8855846 DOI: 10.1080/15476286.2021.2015173] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
High-fidelity translation was considered a requirement for living cells. The frozen accident theory suggested that any deviation from the standard genetic code should result in the production of so much mis-made and non-functional proteins that cells cannot remain viable. Studies in bacterial, yeast, and mammalian cells show that significant levels of mistranslation (1–10% per codon) can be tolerated or even beneficial under conditions of oxidative stress. Single tRNA mutants, which occur naturally in the human population, can lead to amino acid mis-incorporation at a codon or set of codons. The rate or level of mistranslation can be difficult or impossible to measure in live cells. We developed a novel red fluorescent protein reporter that is sensitive to serine (Ser) mis-incorporation at proline (Pro) codons. The mCherry Ser151Pro mutant is efficiently produced in Escherichia coli but non-fluorescent. We demonstrated in cells and with purified mCherry protein that the fluorescence of mCherry Ser151Pro is rescued by two different tRNASer gene variants that were mutated to contain the Pro (UGG) anticodon. Ser mis-incorporation was confirmed by mass spectrometry. Remarkably, E. coli tolerated mistranslation rates of ~10% per codon with negligible reduction in growth rate. Conformational sampling simulations revealed that the Ser151Pro mutant leads to significant changes in the conformational freedom of the chromophore precursor, which is indicative of a defect in chromophore maturation. Together our data suggest that the mCherry Ser151 mutants may be used to report Ser mis-incorporation at multiple other codons, further expanding the ability to measure mistranslation in living cells.
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Affiliation(s)
- Peter Rozik
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Robert Szabla
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Jeremy T Lant
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Rashmi Kiri
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - David E Wright
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Murray Junop
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
| | - Patrick O'Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada.,Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
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9
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Berg MD, Isaacson JR, Cozma E, Genereaux J, Lajoie P, Villén J, Brandl CJ. Regulating Expression of Mistranslating tRNAs by Readthrough RNA Polymerase II Transcription. ACS Synth Biol 2021; 10:3177-3189. [PMID: 34726901 PMCID: PMC8765249 DOI: 10.1021/acssynbio.1c00461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Transfer RNA (tRNA)
variants that alter the genetic code increase
protein diversity and have many applications in synthetic biology.
Since the tRNA variants can cause a loss of proteostasis, regulating
their expression is necessary to achieve high levels of novel protein.
Mechanisms to positively regulate transcription with exogenous activator
proteins like those often used to regulate RNA polymerase II (RNAP
II)-transcribed genes are not applicable to tRNAs as their expression
by RNA polymerase III requires elements internal to the tRNA. Here,
we show that tRNA expression is repressed by overlapping transcription
from an adjacent RNAP II promoter. Regulating the expression of the
RNAP II promoter allows inverse regulation of the tRNA. Placing either
Gal4- or TetR–VP16-activated promoters downstream of a mistranslating
tRNASer variant that misincorporates serine at proline
codons in Saccharomyces cerevisiae allows
mistranslation at a level not otherwise possible because of the toxicity
of the unregulated tRNA. Using this inducible tRNA system, we explore
the proteotoxic effects of mistranslation on yeast cells. High levels
of mistranslation cause cells to arrest in the G1 phase. These cells
are impermeable to propidium iodide, yet growth is not restored upon
repressing tRNA expression. High levels of mistranslation increase
cell size and alter cell morphology. This regulatable tRNA expression
system can be applied to study how native tRNAs and tRNA variants
affect the proteome and other biological processes. Variations of
this inducible tRNA system should be applicable to other eukaryotic
cell types.
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Affiliation(s)
- Matthew D. Berg
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Joshua R. Isaacson
- Department of Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ecaterina Cozma
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick Lajoie
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Christopher J. Brandl
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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10
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Lant JT, Kiri R, Duennwald ML, O'Donoghue P. Formation and persistence of polyglutamine aggregates in mistranslating cells. Nucleic Acids Res 2021; 49:11883-11899. [PMID: 34718744 PMCID: PMC8599886 DOI: 10.1093/nar/gkab898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/03/2021] [Accepted: 09/20/2021] [Indexed: 12/17/2022] Open
Abstract
In neurodegenerative diseases, including pathologies with well-known causative alleles, genetic factors that modify severity or age of onset are not entirely understood. We recently documented the unexpected prevalence of transfer RNA (tRNA) mutants in the human population, including variants that cause amino acid mis-incorporation. We hypothesized that a mistranslating tRNA will exacerbate toxicity and modify the molecular pathology of Huntington's disease-causing alleles. We characterized a tRNAPro mutant that mistranslates proline codons with alanine, and tRNASer mutants, including a tRNASerAGA G35A variant with a phenylalanine anticodon (tRNASerAAA) found in ∼2% of the population. The tRNAPro mutant caused synthetic toxicity with a deleterious huntingtin poly-glutamine (polyQ) allele in neuronal cells. The tRNASerAAA variant showed synthetic toxicity with proteasome inhibition but did not enhance toxicity of the huntingtin allele. Cells mistranslating phenylalanine or proline codons with serine had significantly reduced rates of protein synthesis. Mistranslating cells were slow but effective in forming insoluble polyQ aggregates, defective in protein and aggregate degradation, and resistant to the neuroprotective integrated stress response inhibitor (ISRIB). Our findings identify mistranslating tRNA variants as genetic factors that slow protein aggregation kinetics, inhibit aggregate clearance, and increase drug resistance in cellular models of neurodegenerative disease.
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Affiliation(s)
- Jeremy T Lant
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Rashmi Kiri
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Martin L Duennwald
- Department of Anatomy & Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick O'Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada.,Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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11
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Berg MD, Zhu Y, Ruiz BY, Loll-Krippleber R, Isaacson J, San Luis BJ, Genereaux J, Boone C, Villén J, Brown GW, Brandl CJ. The amino acid substitution affects cellular response to mistranslation. G3-GENES GENOMES GENETICS 2021; 11:6310018. [PMID: 34568909 PMCID: PMC8473984 DOI: 10.1093/g3journal/jkab218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/24/2023]
Abstract
Mistranslation, the misincorporation of an amino acid not specified by the "standard" genetic code, occurs in all organisms. tRNA variants that increase mistranslation arise spontaneously and engineered tRNAs can achieve mistranslation frequencies approaching 10% in yeast and bacteria. Interestingly, human genomes contain tRNA variants with the potential to mistranslate. Cells cope with increased mistranslation through multiple mechanisms, though high levels cause proteotoxic stress. The goal of this study was to compare the genetic interactions and the impact on transcriptome and cellular growth of two tRNA variants that mistranslate at a similar frequency but create different amino acid substitutions in Saccharomyces cerevisiae. One tRNA variant inserts alanine at proline codons whereas the other inserts serine for arginine. Both tRNAs decreased growth rate, with the effect being greater for arginine to serine than for proline to alanine. The tRNA that substituted serine for arginine resulted in a heat shock response. In contrast, heat shock response was minimal for proline to alanine substitution. Further demonstrating the significance of the amino acid substitution, transcriptome analysis identified unique up- and down-regulated genes in response to each mistranslating tRNA. Number and extent of negative synthetic genetic interactions also differed depending upon type of mistranslation. Based on the unique responses observed for these mistranslating tRNAs, we predict that the potential of mistranslation to exacerbate diseases caused by proteotoxic stress depends on the tRNA variant. Furthermore, based on their unique transcriptomes and genetic interactions, different naturally occurring mistranslating tRNAs have the potential to negatively influence specific diseases.
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Affiliation(s)
- Matthew D Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada.,Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Yanrui Zhu
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Bianca Y Ruiz
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Raphaël Loll-Krippleber
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Joshua Isaacson
- Department of Biology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Bryan-Joseph San Luis
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Charles Boone
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Grant W Brown
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada
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Deparis Q, Duitama J, Foulquié-Moreno MR, Thevelein JM. Whole-Genome Transformation Promotes tRNA Anticodon Suppressor Mutations under Stress. mBio 2021; 12:e03649-20. [PMID: 33758086 PMCID: PMC8092322 DOI: 10.1128/mbio.03649-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/16/2021] [Indexed: 11/20/2022] Open
Abstract
tRNAs are encoded by a large gene family, usually with several isogenic tRNAs interacting with the same codon. Mutations in the anticodon region of other tRNAs can overcome specific tRNA deficiencies. Phylogenetic analysis suggests that such mutations have occurred in evolution, but the driving force is unclear. We show that in yeast suppressor mutations in other tRNAs are able to overcome deficiency of the essential TRT2-encoded tRNAThrCGU at high temperature (40°C). Surprisingly, these tRNA suppressor mutations were obtained after whole-genome transformation with DNA from thermotolerant Kluyveromyces marxianus or Ogataea polymorpha strains but from which the mutations did apparently not originate. We suggest that transient presence of donor DNA in the host facilitates proliferation at high temperature and thus increases the chances for occurrence of spontaneous mutations suppressing defective growth at high temperature. Whole-genome sequence analysis of three transformants revealed only four to five nonsynonymous mutations of which one causing TRT2 anticodon stem stabilization and two anticodon mutations in non-threonyl-tRNAs, tRNALysCUU and tRNAeMetCAU, were causative. Both anticodon mutations suppressed lethality of TRT2 deletion and apparently caused the respective tRNAs to become novel substrates for threonyl-tRNA synthetase. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) data could not detect any significant mistranslation, and reverse transcription-quantitative PCR results contradicted induction of the unfolded protein response. We suggest that stress conditions have been a driving force in evolution for the selection of anticodon-switching mutations in tRNAs as revealed by phylogenetic analysis.IMPORTANCE In this work, we have identified for the first time the causative elements in a eukaryotic organism introduced by applying whole-genome transformation and responsible for the selectable trait of interest, i.e., high temperature tolerance. Surprisingly, the whole-genome transformants contained just a few single nucleotide polymorphisms (SNPs), which were unrelated to the sequence of the donor DNA. In each of three independent transformants, we have identified a SNP in a tRNA, either stabilizing the essential tRNAThrCGU at high temperature or switching the anticodon of tRNALysCUU or tRNAeMetCAU into CGU, which is apparently enough for in vivo recognition by threonyl-tRNA synthetase. LC-MS/MS analysis indeed indicated absence of significant mistranslation. Phylogenetic analysis showed that similar mutations have occurred throughout evolution and we suggest that stress conditions may have been a driving force for their selection. The low number of SNPs introduced by whole-genome transformation may favor its application for improvement of industrial yeast strains.
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Affiliation(s)
- Quinten Deparis
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Center for Microbiology, VIB, Leuven-Heverlee, Flanders, Belgium
| | - Jorge Duitama
- Systems and Computing Engineering Department, Universidad de los Andes, Bogotá, Colombia
| | - Maria R Foulquié-Moreno
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Center for Microbiology, VIB, Leuven-Heverlee, Flanders, Belgium
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Center for Microbiology, VIB, Leuven-Heverlee, Flanders, Belgium
- NovelYeast bv, Open Bio-Incubator, Erasmus High School, Brussels (Jette), Belgium
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Berg MD, Brandl CJ. Transfer RNAs: diversity in form and function. RNA Biol 2021; 18:316-339. [PMID: 32900285 PMCID: PMC7954030 DOI: 10.1080/15476286.2020.1809197] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/31/2020] [Accepted: 08/08/2020] [Indexed: 12/11/2022] Open
Abstract
As the adaptor that decodes mRNA sequence into protein, the basic aspects of tRNA structure and function are central to all studies of biology. Yet the complexities of their properties and cellular roles go beyond the view of tRNAs as static participants in protein synthesis. Detailed analyses through more than 60 years of study have revealed tRNAs to be a fascinatingly diverse group of molecules in form and function, impacting cell biology, physiology, disease and synthetic biology. This review analyzes tRNA structure, biosynthesis and function, and includes topics that demonstrate their diversity and growing importance.
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Affiliation(s)
- Matthew D. Berg
- Department of Biochemistry, The University of Western Ontario, London, Canada
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14
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Chemical-Genetic Interactions with the Proline Analog L-Azetidine-2-Carboxylic Acid in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2020; 10:4335-4345. [PMID: 33082270 PMCID: PMC7718759 DOI: 10.1534/g3.120.401876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Non-proteinogenic amino acids, such as the proline analog L-azetidine-2-carboxylic acid (AZC), are detrimental to cells because they are mis-incorporated into proteins and lead to proteotoxic stress. Our goal was to identify genes that show chemical-genetic interactions with AZC in Saccharomyces cerevisiae and thus also potentially define the pathways cells use to cope with amino acid mis-incorporation. Screening the yeast deletion and temperature sensitive collections, we found 72 alleles with negative chemical-genetic interactions with AZC treatment and 12 alleles that suppress AZC toxicity. Many of the genes with negative chemical-genetic interactions are involved in protein quality control pathways through the proteasome. Genes involved in actin cytoskeleton organization and endocytosis also had negative chemical-genetic interactions with AZC. Related to this, the number of actin patches per cell increases upon AZC treatment. Many of the same cellular processes were identified to have interactions with proteotoxic stress caused by two other amino acid analogs, canavanine and thialysine, or a mistranslating tRNA variant that mis-incorporates serine at proline codons. Alleles that suppressed AZC-induced toxicity functioned through the amino acid sensing TOR pathway or controlled amino acid permeases required for AZC uptake. Further suggesting the potential of genetic changes to influence the cellular response to proteotoxic stress, overexpressing many of the genes that had a negative chemical-genetic interaction with AZC suppressed AZC toxicity.
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15
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Zhu Y, Berg MD, Yang P, Loll-Krippleber R, Brown GW, Brandl CJ. Mistranslating tRNA identifies a deleterious S213P mutation in theSaccharomyces cerevisiaeeco1-1allele. Biochem Cell Biol 2020; 98:624-630. [DOI: 10.1139/bcb-2020-0151] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Mistranslation occurs when an amino acid not specified by the standard genetic code is incorporated during translation. Since the ribosome does not read the amino acid, tRNA variants aminoacylated with a non-cognate amino acid or containing a non-cognate anticodon dramatically increase the frequency of mistranslation. In a systematic genetic analysis, we identified a suppression interaction between tRNASerUGG, G26A, which mistranslates proline codons by inserting serine, and eco1-1, a temperature sensitive allele of the gene encoding an acetyltransferase required for sister chromatid cohesion. The suppression was partial, with a tRNA that inserts alanine at proline codons and not apparent for a tRNA that inserts serine at arginine codons. Sequencing of the eco1-1 allele revealed a mutation that would convert the highly conserved serine 213 within β7 of the GCN5-related N-acetyltransferase core to proline. Mutation of P213 in eco1-1 back to the wild-type serine restored the function of the enzyme at elevated temperatures. Our results indicate the utility of mistranslating tRNA variants to identify functionally relevant mutations and identify eco1 as a reporter for mistranslation. We propose that mistranslation could be used as a tool to treat genetic disease.
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Affiliation(s)
- Yanrui Zhu
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Matthew D. Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Phoebe Yang
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Raphaël Loll-Krippleber
- Donnelly Centre for Cellular and Biomolecular Research, Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Grant W. Brown
- Donnelly Centre for Cellular and Biomolecular Research, Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Christopher J. Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
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16
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Impact of Pus1 Pseudouridine Synthase on Specific Decoding Events in Saccharomyces cerevisiae. Biomolecules 2020; 10:biom10050729. [PMID: 32392804 PMCID: PMC7277083 DOI: 10.3390/biom10050729] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 04/30/2020] [Accepted: 05/05/2020] [Indexed: 12/19/2022] Open
Abstract
Pus1-dependent pseudouridylation occurs in many tRNAs and at multiple positions, yet the functional impact of this modification is incompletely understood. We analyzed the consequences of PUS1 deletion on the essential decoding of CAG (Gln) codons by tRNAGlnCUG in yeast. Synthetic lethality was observed upon combining the modification defect with destabilized variants of tRNAGlnCUG, pointing to a severe CAG-decoding defect of the hypomodified tRNA. In addition, we demonstrated that misreading of UAG stop codons by a tRNAGlnCUG variant is positively affected by Pus1. Genetic approaches further indicated that mildly elevated temperature decreases the decoding efficiency of CAG and UAG via destabilized tRNAGlnCAG variants. We also determined the misreading of CGC (Arg) codons by tRNAHisGUG, where the CGC decoder tRNAArgICG contains Pus1-dependent pseudouridine, but not the mistranslating tRNAHis. We found that the absence of Pus1 increased CGC misreading by tRNAHis, demonstrating a positive role of the modification in the competition against non-synonymous near-cognate tRNA. Part of the in vivo decoding defects and phenotypes in pus1 mutants and strains carrying destabilized tRNAGlnCAG were suppressible by additional deletion of the rapid tRNA decay (RTD)-relevant MET22, suggesting the involvement of RTD-mediated tRNA destabilization.
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