1
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Simonenko SY, Bogdanova DA, Kuldyushev NA. Emerging Roles of Vitamin B 12 in Aging and Inflammation. Int J Mol Sci 2024; 25:5044. [PMID: 38732262 PMCID: PMC11084641 DOI: 10.3390/ijms25095044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 04/28/2024] [Accepted: 04/29/2024] [Indexed: 05/13/2024] Open
Abstract
Vitamin B12 (cobalamin) is an essential nutrient for humans and animals. Metabolically active forms of B12-methylcobalamin and 5-deoxyadenosylcobalamin are cofactors for the enzymes methionine synthase and mitochondrial methylmalonyl-CoA mutase. Malfunction of these enzymes due to a scarcity of vitamin B12 leads to disturbance of one-carbon metabolism and impaired mitochondrial function. A significant fraction of the population (up to 20%) is deficient in vitamin B12, with a higher rate of deficiency among elderly people. B12 deficiency is associated with numerous hallmarks of aging at the cellular and organismal levels. Cellular senescence is characterized by high levels of DNA damage by metabolic abnormalities, increased mitochondrial dysfunction, and disturbance of epigenetic regulation. B12 deficiency could be responsible for or play a crucial part in these disorders. In this review, we focus on a comprehensive analysis of molecular mechanisms through which vitamin B12 influences aging. We review new data about how deficiency in vitamin B12 may accelerate cellular aging. Despite indications that vitamin B12 has an important role in health and healthy aging, knowledge of the influence of vitamin B12 on aging is still limited and requires further research.
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Affiliation(s)
- Sergey Yu. Simonenko
- Research Center for Translational Medicine, Sirius University of Science and Technology, 354340 Sochi, Russia;
| | - Daria A. Bogdanova
- Division of Immunobiology and Biomedicine, Center for Genetics and Life Sciences, Sirius University of Science and Technology, 354340 Sochi, Russia
| | - Nikita A. Kuldyushev
- Research Center for Translational Medicine, Sirius University of Science and Technology, 354340 Sochi, Russia;
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2
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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: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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3
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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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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4
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Aledo JC. The Role of Methionine Residues in the Regulation of Liquid-Liquid Phase Separation. Biomolecules 2021; 11:biom11081248. [PMID: 34439914 PMCID: PMC8394241 DOI: 10.3390/biom11081248] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 08/12/2021] [Accepted: 08/18/2021] [Indexed: 02/07/2023] Open
Abstract
Membraneless organelles are non-stoichiometric supramolecular structures in the micron scale. These structures can be quickly assembled/disassembled in a regulated fashion in response to specific stimuli. Membraneless organelles contribute to the spatiotemporal compartmentalization of the cell, and they are involved in diverse cellular processes often, but not exclusively, related to RNA metabolism. Liquid-liquid phase separation, a reversible event involving demixing into two distinct liquid phases, provides a physical framework to gain insights concerning the molecular forces underlying the process and how they can be tuned according to the cellular needs. Proteins able to undergo phase separation usually present a modular architecture, which favors a multivalency-driven demixing. We discuss the role of low complexity regions in establishing networks of intra- and intermolecular interactions that collectively control the phase regime. Post-translational modifications of the residues present in these domains provide a convenient strategy to reshape the residue-residue interaction networks that determine the dynamics of phase separation. Focus will be placed on those proteins with low complexity domains exhibiting a biased composition towards the amino acid methionine and the prominent role that reversible methionine sulfoxidation plays in the assembly/disassembly of biomolecular condensates.
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Affiliation(s)
- Juan Carlos Aledo
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
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5
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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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6
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Avcilar-Kucukgoze I, Kashina A. Hijacking tRNAs From Translation: Regulatory Functions of tRNAs in Mammalian Cell Physiology. Front Mol Biosci 2020; 7:610617. [PMID: 33392265 PMCID: PMC7773854 DOI: 10.3389/fmolb.2020.610617] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 11/10/2020] [Indexed: 12/12/2022] Open
Abstract
Transfer tRNAs (tRNAs) are small non-coding RNAs that are highly conserved in all kingdoms of life. Originally discovered as the molecules that deliver amino acids to the growing polypeptide chain during protein synthesis, tRNAs have been believed for a long time to play exclusive role in translation. However, recent studies have identified key roles for tRNAs and tRNA-derived small RNAs in multiple other processes, including regulation of transcription and translation, posttranslational modifications, stress response, and disease. These emerging roles suggest that tRNAs may be central players in the complex machinery of biological regulatory pathways. Here we overview these non-canonical roles of tRNA in normal physiology and disease, focusing largely on eukaryotic and mammalian systems.
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Affiliation(s)
- Irem Avcilar-Kucukgoze
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Anna Kashina
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
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7
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Berg MD, Zhu Y, Isaacson J, Genereaux J, Loll-Krippleber R, Brown GW, Brandl CJ. Chemical-Genetic Interactions with the Proline Analog L-Azetidine-2-Carboxylic Acid in Saccharomyces cerevisiae. G3 (Bethesda) 2020; 10:4335-45. [PMID: 33082270 DOI: 10.1534/g3.120.401876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [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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8
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Aledo JC. Methionine in proteins: The Cinderella of the proteinogenic amino acids. Protein Sci 2019; 28:1785-1796. [PMID: 31359525 DOI: 10.1002/pro.3698] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 11/09/2022]
Abstract
Methionine in proteins, apart from its role in the initiation of translation, is assumed to play a simple structural role in the hydrophobic core, in a similar way to other hydrophobic amino acids such as leucine, isoleucine, and valine. However, research from a number of laboratories supports the concept that methionine serves as an important cellular antioxidant, stabilizes the structure of proteins, participates in the sequence-independent recognition of protein surfaces, and can act as a regulatory switch through reversible oxidation and reduction. Despite all these evidences, the role of methionine in protein structure and function is largely overlooked by most biochemists. Thus, the main aim of the current article is not so much to carry out an exhaustive review of the many and diverse processes in which methionine residues are involved, but to review some illustrative examples that may help the nonspecialized reader to form a richer and more precise insight regarding the role-played by methionine residues in such processes.
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Affiliation(s)
- Juan C Aledo
- Departamento de Biología Molecular y Bioquímica. Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
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9
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Lourenço Dos Santos S, Petropoulos I, Friguet B. The Oxidized Protein Repair Enzymes Methionine Sulfoxide Reductases and Their Roles in Protecting against Oxidative Stress, in Ageing and in Regulating Protein Function. Antioxidants (Basel) 2018; 7:E191. [PMID: 30545068 DOI: 10.3390/antiox7120191] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/31/2022] Open
Abstract
Cysteine and methionine residues are the amino acids most sensitive to oxidation by reactive oxygen species. However, in contrast to other amino acids, certain cysteine and methionine oxidation products can be reduced within proteins by dedicated enzymatic repair systems. Oxidation of cysteine first results in either the formation of a disulfide bridge or a sulfenic acid. Sulfenic acid can be converted to disulfide or sulfenamide or further oxidized to sulfinic acid. Disulfide can be easily reversed by different enzymatic systems such as the thioredoxin/thioredoxin reductase and the glutaredoxin/glutathione/glutathione reductase systems. Methionine side chains can also be oxidized by reactive oxygen species. Methionine oxidation, by the addition of an extra oxygen atom, leads to the generation of methionine sulfoxide. Enzymatically catalyzed reduction of methionine sulfoxide is achieved by either methionine sulfoxide reductase A or methionine sulfoxide reductase B, also referred as to the methionine sulfoxide reductases system. This oxidized protein repair system is further described in this review article in terms of its discovery and biologically relevant characteristics, and its important physiological roles in protecting against oxidative stress, in ageing and in regulating protein function.
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10
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Abstract
The pool of transfer RNA (tRNA) molecules in cells allows the ribosome to decode genetic information. This repertoire of molecular decoders is positioned in the crossroad of the genome, the transcriptome, and the proteome. Omics and systems biology now allow scientists to explore the entire repertoire of tRNAs of many organisms, revealing basic exciting biology. The tRNA gene set of hundreds of species is now characterized, in addition to the tRNA genes of organelles and viruses. Genes encoding tRNAs for certain anticodon types appear in dozens of copies in a genome, while others are universally absent from any genome. Transcriptome measurement of tRNAs is challenging, but in recent years new technologies have allowed researchers to determine the dynamic expression patterns of tRNAs. These advances reveal that availability of ready-to-translate tRNA molecules is highly controlled by several transcriptional and posttranscriptional regulatory processes. This regulation shapes the proteome according to the cellular state. The tRNA pool profoundly impacts many aspects of cellular and organismal life, including protein expression level, translation accuracy, adequacy of folding, and even mRNA stability. As a result, the shape of the tRNA pool affects organismal health and may participate in causing conditions such as cancer and neurological conditions.
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Affiliation(s)
- Roni Rak
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100 Israel;
| | - Orna Dahan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100 Israel;
| | - Yitzhak Pilpel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100 Israel;
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11
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Lant JT, Berg MD, Sze DHW, Hoffman KS, Akinpelu IC, Turk MA, Heinemann IU, Duennwald ML, Brandl CJ, O'Donoghue P. Visualizing tRNA-dependent mistranslation in human cells. RNA Biol 2017; 15:567-575. [PMID: 28933646 DOI: 10.1080/15476286.2017.1379645] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
High-fidelity translation and a strictly accurate proteome were originally assumed as essential to life and cellular viability. Yet recent studies in bacteria and eukaryotic model organisms suggest that proteome-wide mistranslation can provide selective advantages and is tolerated in the cell at higher levels than previously thought (one error in 6.9 × 10-4 in yeast) with a limited impact on phenotype. Previously, we selected a tRNAPro containing a single mutation that induces mistranslation with alanine at proline codons in yeast. Yeast tolerate the mistranslation by inducing a heat-shock response and through the action of the proteasome. Here we found a homologous human tRNAPro (G3:U70) mutant that is not aminoacylated with proline, but is an efficient alanine acceptor. In live human cells, we visualized mistranslation using a green fluorescent protein reporter that fluoresces in response to mistranslation at proline codons. In agreement with measurements in yeast, quantitation based on the GFP reporter suggested a mistranslation rate of up to 2-5% in HEK 293 cells. Our findings suggest a stress-dependent phenomenon where mistranslation levels increased during nutrient starvation. Human cells did not mount a detectable heat-shock response and tolerated this level of mistranslation without apparent impact on cell viability. Because humans encode ∼600 tRNA genes and the natural population has greater tRNA sequence diversity than previously appreciated, our data also demonstrate a cell-based screen with the potential to elucidate mutations in tRNAs that may contribute to or alleviate disease.
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Affiliation(s)
- Jeremy T Lant
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | - Matthew D Berg
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | - Daniel H W Sze
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | - Kyle S Hoffman
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | | | - Matthew A Turk
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | - Ilka U Heinemann
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | - Martin L Duennwald
- b Department of Pathology , The University of Western Ontario , London , ON , Canada
| | - Christopher J Brandl
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada
| | - Patrick O'Donoghue
- a Department of Biochemistry , The University of Western Ontario , London , ON , Canada.,c Department of Chemistry , The University of Western Ontario , London , ON , Canada
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12
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Mohler K, Ibba M. Translational fidelity and mistranslation in the cellular response to stress. Nat Microbiol 2017; 2:17117. [PMID: 28836574 DOI: 10.1038/nmicrobiol.2017.117] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 06/20/2017] [Indexed: 11/08/2022]
Abstract
Faithful translation of mRNA into the corresponding polypeptide is a complex multistep process, requiring accurate amino acid selection, transfer RNA (tRNA) charging and mRNA decoding on the ribosome. Key players in this process are aminoacyl-tRNA synthetases (aaRSs), which not only catalyse the attachment of cognate amino acids to their respective tRNAs, but also selectively hydrolyse incorrectly activated non-cognate amino acids and/or misaminoacylated tRNAs. This aaRS proofreading provides quality control checkpoints that exclude non-cognate amino acids during translation, and in so doing helps to prevent the formation of an aberrant proteome. However, despite the intrinsic need for high accuracy during translation, and the widespread evolutionary conservation of aaRS proofreading pathways, requirements for translation quality control vary depending on cellular physiology and changes in growth conditions, and translation errors are not always detrimental. Recent work has demonstrated that mistranslation can also be beneficial to cells, and some organisms have selected for a higher degree of mistranslation than others. The aims of this Review Article are to summarize the known mechanisms of protein translational fidelity and explore the diversity and impact of mistranslation events as a potentially beneficial response to environmental and cellular stress.
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13
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Abstract
Global protein mistranslation with methionine has been shown to be a conserved biological process that affords distinct functional advantages in all three domains of life. In all instances, methionine mistranslation occurs through a regulated process where low-fidelity forms of methionyl-tRNA synthetase are conditionally induced to mischarge non-methionyl-tRNAs with methionine followed by the utilization of the misacylated tRNAs in translation. In mammals, methionine mistranslation contributes to oxidative stress response; in the hyperthermophilic archaeon Aeropyrum pernix, methionine mistranslation produces proteins that are better adapted to low temperature growth; in E. coli, methionine mistranslation increases resistance to antibiotics and chemical stressors. The phenotypic benefits conferred by tRNA mismethionylation suggest that it should be a widespread adaptational mechanism in diverse bacterial lineages, yet this response has only been described in E. coli. Furthermore, previous microbial investigations on this response have been confined to axenic laboratory cultures. It was unknown whether tRNA mismethionylation was relevant in a natural microbial habitat. Here we show that four abundant gut microbiotal genera belonging to the Firmicutes and Bacteroidetes phyla perform constitutive tRNA misacylation with methionine in the mouse cecum in situ. These results reveal the ubiquity of the tRNA mismethionylation process among bacteria and implicate the potential importance of this response for subsistence and adaptation in natural habitats.
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Affiliation(s)
- Michael H Schwartz
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Committee on Microbiology, University of Chicago, Chicago, IL, 60637, USA.
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Committee on Microbiology, University of Chicago, Chicago, IL, 60637, USA.
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14
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Abstract
Mistranslation describes errors during protein synthesis that prevent the amino acid sequences specified in the genetic code from being reflected within proteins. For a long time, mistranslation has largely been considered an aberrant cellular process that cells actively avoid at all times. However, recent evidence has demonstrated that cells from all three domains of life not only tolerate certain levels and forms of mistranslation, but actively induce mistranslation under certain circumstances. To this end, dedicated biological mechanisms have recently been found to reduce translational fidelity, which indicates that mistranslation is not exclusively an erroneous process and can even benefit cells in particular cellular contexts. There currently exists a spectrum of mistranslational processes that differ not only in their origins, but also in their molecular and cellular effects. These findings suggest that the optimal degree of translational fidelity largely depends on a specific cellular context. This review aims to conceptualize the basis and functional consequence of the diverse types of mistranslation that have been described so far.
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Affiliation(s)
- Michael H Schwartz
- a Department of Biochemistry and Molecular Biology , University of Chicago, Chicago , IL , USA
| | - Tao Pan
- a Department of Biochemistry and Molecular Biology , University of Chicago, Chicago , IL , USA
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15
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Sun L, Gomes AC, He W, Zhou H, Wang X, Pan DW, Schimmel P, Pan T, Yang XL. Evolutionary Gain of Alanine Mischarging to Noncognate tRNAs with a G4:U69 Base Pair. J Am Chem Soc 2016; 138:12948-12955. [PMID: 27622773 DOI: 10.1021/jacs.6b07121] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Fidelity of translation, which is predominately dictated by the accuracy of aminoacyl-tRNA synthetases in pairing amino acids with correct tRNAs, is of central importance in biology. Yet, deliberate modifications of translational fidelity can be beneficial. Here we found human and not E. coli AlaRS has an intrinsic capacity for mispairing alanine onto nonalanyl-tRNAs including tRNACys. Consistently, a cysteine-to-alanine substitution was found in a reporter protein expressed in human cells. All human AlaRS-mischarged tRNAs have a G4:U69 base pair in the acceptor stem. The base pair is required for the mischarging. By solving the crystal structure of human AlaRS and comparing it to that of E. coli AlaRS, we identified a key sequence divergence between eukaryotes and bacteria that influences mischarging. Thus, the expanded tRNA specificity of AlaRS appears to be an evolutionary gain-of-function to provide posttranscriptional alanine substitutions in eukaryotic proteins for potential regulations.
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Affiliation(s)
- Litao Sun
- Department of Cell and Molecular Biology, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Ana Cristina Gomes
- Department of Biochemistry and Molecular Biology, University of Chicago , Chicago, Illinois 60637, United States
| | - Weiwei He
- Department of Chemical Physiology, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Huihao Zhou
- Department of Cell and Molecular Biology, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Xiaoyun Wang
- Department of Biochemistry and Molecular Biology, University of Chicago , Chicago, Illinois 60637, United States
| | - David W Pan
- Department of Biochemistry and Molecular Biology, University of Chicago , Chicago, Illinois 60637, United States
| | - Paul Schimmel
- Department of Cell and Molecular Biology, The Scripps Research Institute , La Jolla, California 92037, United States
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago , Chicago, Illinois 60637, United States
| | - Xiang-Lei Yang
- Department of Cell and Molecular Biology, The Scripps Research Institute , La Jolla, California 92037, United States.,Department of Chemical Physiology, The Scripps Research Institute , La Jolla, California 92037, United States
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16
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Schwartz MH, Waldbauer JR, Zhang L, Pan T. Global tRNA misacylation induced by anaerobiosis and antibiotic exposure broadly increases stress resistance in Escherichia coli. Nucleic Acids Res 2016; 44:10292-10303. [PMID: 27672035 PMCID: PMC5137444 DOI: 10.1093/nar/gkw856] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/14/2016] [Accepted: 09/16/2016] [Indexed: 12/22/2022] Open
Abstract
High translational fidelity is commonly considered a requirement for optimal cellular health and protein function. However, recent findings have shown that inducible mistranslation specifically with methionine engendered at the tRNA charging level occurs in mammalian cells, yeast and archaea, yet it was unknown whether bacteria were capable of mounting a similar response. Here, we demonstrate that Escherichia coli misacylates non-methionyl-tRNAs with methionine in response to anaerobiosis and antibiotic exposure via the methionyl–tRNA synthetase (MetRS). Two MetRS succinyl-lysine modifications independently confer high tRNA charging fidelity to the otherwise promiscuous, unmodified enzyme. Strains incapable of tRNA mismethionylation are less adept at growth in the presence of antibiotics and stressors. The presence of tRNA mismethionylation and its potential role in mistranslation within the bacterial domain establishes this response as a pervasive biological mechanism and connects it to diverse cellular functions and modes of fitness.
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Affiliation(s)
- Michael H Schwartz
- Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA.,Committee on Microbiology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA
| | - Jacob R Waldbauer
- Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave., Chicago, IL 60637, USA
| | - Lichun Zhang
- Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave., Chicago, IL 60637, USA
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA .,Committee on Microbiology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA
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Schwartz MH, Pan T. Determining the fidelity of tRNA aminoacylation via microarrays. Methods 2017; 113:27-33. [PMID: 27639882 DOI: 10.1016/j.ymeth.2016.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 08/30/2016] [Accepted: 09/12/2016] [Indexed: 12/28/2022] Open
Abstract
The fidelity of tRNA aminoacylation is a critical determinant for the ultimate accuracy of protein synthesis. Although aminoacyl-tRNA synthetases are assumed to consistently maintain high tRNA charging fidelity, recent evidence has demonstrated that the fidelity of the aminoacylation reaction can be actively regulated and liable to change. Accordingly, the ability to conveniently assay the fidelity of tRNA charging is becoming increasingly relevant for studying mistranslation. Here we describe a combined radioactivity and microarray based method that can quantitatively elucidate which individual cognate or noncognate tRNA isoacceptors are charged with amino acid. In this technique, in vitro tRNA charging reactions or in vivo pulse-labeling is performed using a radiolabeled amino acid and tRNA microarrays are used to distinguish tRNA isoacceptors in total tRNA. During the tRNA array hybridization, each tRNA will hybridize to its unique probe and subsequent phosphorimaging of the array can determine which tRNAs were aminoacylated with the radiolabeled amino acid. The method can be used to assess the fidelity of tRNA charging in vivo or in vitro and can be applied to any organism with annotated tRNA genes.
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Wang X, Chow CR, Ebine K, Lee J, Rosner MR, Pan T, Munshi HG. Interaction of tRNA with MEK2 in pancreatic cancer cells. Sci Rep 2016; 6:28260. [PMID: 27301426 DOI: 10.1038/srep28260] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/01/2016] [Indexed: 01/07/2023] Open
Abstract
Although the translational function of tRNA has long been established, extra translational functions of tRNA are still being discovered. We previously developed a computational method to systematically predict new tRNA-protein complexes and experimentally validated six candidate proteins, including the mitogen-activated protein kinase kinase 2 (MEK2), that interact with tRNA in HEK293T cells. However, consequences of the interaction between tRNA and these proteins remain to be elucidated. Here we tested the consequence of the interaction between tRNA and MEK2 in pancreatic cancer cell lines. We also generated disease and drug resistance-derived MEK2 mutants (Q60P, P128Q, S154F, E207K) to evaluate the function of the tRNA-MEK2 interaction. Our results demonstrate that tRNA interacts with the wild-type and mutant MEK2 in pancreatic cancer cells; furthermore, the MEK2 inhibitor U0126 significantly reduces the tRNA-MEK2 interaction. In addition, tRNA affects the catalytic activity of the wild type and mutant MEK2 proteins in different ways. Overall, our findings demonstrate the interaction of tRNA with MEK2 in pancreatic cancer cells and suggest that tRNA may impact MEK2 activity in cancer cells.
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Abstract
Poxviruses are large double-stranded DNA viruses that form viral factories in the cytoplasm of host cells. These viruses encode their own transcription machinery, but rely on host translation for protein synthesis. Thus, poxviruses have to cope with and, in most cases, reprogram host translation regulation. Granule structures, called antiviral granules (AVGs), have been observed surrounding poxvirus viral factories. AVG formation is associated with abortive poxvirus infection, and AVGs contain proteins that are typically found in stress granules (SGs). With certain mutant poxviruses lack of immunoregulatory factor(s), we can specifically examine the mechanisms that drive the formation of these structures. In fact, cytoplasmic macromolecular complexes form during many viral infections and contain sensing molecules that can help reprogram transcription. More importantly, the similarity between AVGs and cytoplasmic structures formed during RNA and DNA sensing events prompts us to reconsider the cause and consequence of these AVGs. In this review, we first summarize recent findings regarding how poxvirus manipulates host translation. Next, we compare and contrast SGs and AVGs. Finally, we review recent findings regarding RNA- and especially DNA-sensing bodies observed during viral infection.
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Affiliation(s)
- Jason Liem
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
| | - Jia Liu
- Department of Microbiology and Immunology, Center for Microbial Pathogenesis and Host Inflammatory Responses, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
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