1
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Ward C, Beharry A, Tennakoon R, Rozik P, Wilhelm SDP, Heinemann IU, O’Donoghue P. Mechanisms and Delivery of tRNA Therapeutics. Chem Rev 2024; 124:7976-8008. [PMID: 38801719 PMCID: PMC11212642 DOI: 10.1021/acs.chemrev.4c00142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/11/2024] [Accepted: 04/26/2024] [Indexed: 05/29/2024]
Abstract
Transfer ribonucleic acid (tRNA) therapeutics will provide personalized and mutation specific medicines to treat human genetic diseases for which no cures currently exist. The tRNAs are a family of adaptor molecules that interpret the nucleic acid sequences in our genes into the amino acid sequences of proteins that dictate cell function. Humans encode more than 600 tRNA genes. Interestingly, even healthy individuals contain some mutant tRNAs that make mistakes. Missense suppressor tRNAs insert the wrong amino acid in proteins, and nonsense suppressor tRNAs read through premature stop signals to generate full length proteins. Mutations that underlie many human diseases, including neurodegenerative diseases, cancers, and diverse rare genetic disorders, result from missense or nonsense mutations. Thus, specific tRNA variants can be strategically deployed as therapeutic agents to correct genetic defects. We review the mechanisms of tRNA therapeutic activity, the nature of the therapeutic window for nonsense and missense suppression as well as wild-type tRNA supplementation. We discuss the challenges and promises of delivering tRNAs as synthetic RNAs or as gene therapies. Together, tRNA medicines will provide novel treatments for common and rare genetic diseases in humans.
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Affiliation(s)
- Cian Ward
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Aruun Beharry
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Rasangi Tennakoon
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Peter Rozik
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Sarah D. P. Wilhelm
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ilka U. Heinemann
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick O’Donoghue
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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2
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Wright DE, O’Donoghue P. Biosynthesis, Engineering, and Delivery of Selenoproteins. Int J Mol Sci 2023; 25:223. [PMID: 38203392 PMCID: PMC10778597 DOI: 10.3390/ijms25010223] [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] [Received: 11/15/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Selenocysteine (Sec) was discovered as the 21st genetically encoded amino acid. In nature, site-directed incorporation of Sec into proteins requires specialized biosynthesis and recoding machinery that evolved distinctly in bacteria compared to archaea and eukaryotes. Many organisms, including higher plants and most fungi, lack the Sec-decoding trait. We review the discovery of Sec and its role in redox enzymes that are essential to human health and important targets in disease. We highlight recent genetic code expansion efforts to engineer site-directed incorporation of Sec in bacteria and yeast. We also review methods to produce selenoproteins with 21 or more amino acids and approaches to delivering recombinant selenoproteins to mammalian cells as new applications for selenoproteins in synthetic biology.
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Affiliation(s)
- David E. Wright
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada;
| | - Patrick O’Donoghue
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada;
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
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3
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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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4
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Siddika T, Heinemann IU, O'Donoghue P. Expanding codon size. eLife 2022; 11:78869. [PMID: 35543705 PMCID: PMC9094744 DOI: 10.7554/elife.78869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Engineering transfer RNAs to read codons consisting of four bases requires changes in tRNA that go beyond the anticodon sequence.
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Affiliation(s)
- Tarana Siddika
- Department of Biochemistry, The University of Western Ontario, London, Canada
| | - Ilka U Heinemann
- Department of Biochemistry, The University of Western Ontario, London, Canada
| | - Patrick O'Donoghue
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Canada
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5
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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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6
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Kondratyeva LG, Dyachkova MS, Galchenko AV. The Origin of Genetic Code and Translation in the Framework of Current Concepts on the Origin of Life. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:150-169. [PMID: 35508902 DOI: 10.1134/s0006297922020079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The origin of genetic code and translation system is probably the central and most difficult problem in the investigations on the origin of life and one of the most complex problems in the evolutionary biology in general. There are multiple hypotheses on the emergence and development of existing genetic systems that propose the mechanisms for the origin and early evolution of genetic code, as well as for the emergence of replication and translation. Here, we discuss the most well-known of these hypotheses, although none of them provides a description of the early evolution of genetic systems without gaps and assumptions. The RNA world hypothesis is a currently prevailing scientific idea on the early evolution of biological and pre-biological structures, the main advantage of which is the assumption that RNAs as the first living systems were self-sufficient, i.e., capable of functioning as both catalysts and templates. However, this hypothesis has also significant limitations. In particular, no ribozymes with processive polymerase activity have been yet discovered or synthesized. Taking into account the mutual need of proteins and nucleic acids in each other in the current world, many authors propose the early evolution scenarios based on the co-evolution of these two classes of organic molecules. They postulate that the emergence of translation was necessary for the replication of nucleic acids, in contrast to the RNA world hypothesis, according to which the emergence of translation was preceded by the era of self-replicating RNAs. Although such scenarios are less parsimonious from the evolutionary point of view, since they require simultaneous emergence and evolution of two classes of organic molecules, as well as the emergence of synchronized replication and translation, their major advantage is that they explain the development of processive and much more accurate protein-dependent replication.
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Affiliation(s)
- Liya G Kondratyeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | | | - Alexey V Galchenko
- Peoples' Friendship University of Russia (RUDN University), Moscow, 117198, Russia.
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7
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Komar AA. A Code Within a Code: How Codons Fine-Tune Protein Folding in the Cell. BIOCHEMISTRY (MOSCOW) 2021; 86:976-991. [PMID: 34488574 DOI: 10.1134/s0006297921080083] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The genetic code sets the correspondence between the sequence of a given nucleotide triplet in an mRNA molecule, called a codon, and the amino acid that is added to the growing polypeptide chain during protein synthesis. With four bases (A, G, U, and C), there are 64 possible triplet codons: 61 sense codons (encoding amino acids) and 3 nonsense codons (so-called, stop codons that define termination of translation). In most organisms, there are 20 common/standard amino acids used in protein synthesis; thus, the genetic code is redundant with most amino acids (with the exception of Met and Trp) are being encoded by more than one (synonymous) codon. Synonymous codons were initially presumed to have entirely equivalent functions, however, the finding that synonymous codons are not present at equal frequencies in mRNA suggested that the specific codon choice might have functional implications beyond coding for amino acid. Observation of nonequivalent use of codons in mRNAs implied a possibility of the existence of auxiliary information in the genetic code. Indeed, it has been found that genetic code contains several layers of such additional information and that synonymous codons are strategically placed within mRNAs to ensure a particular translation kinetics facilitating and fine-tuning co-translational protein folding in the cell via step-wise/sequential structuring of distinct regions of the polypeptide chain emerging from the ribosome at different points in time. This review summarizes key findings in the field that have identified the role of synonymous codons and their usage in protein folding in the cell.
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Affiliation(s)
- Anton A Komar
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH 44115, USA. .,Department of Biochemistry and Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106, USA.,Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.,DAPCEL, Inc., Cleveland, OH 44106, USA
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8
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Heckmann CM, Paradisi F. Looking Back: A Short History of the Discovery of Enzymes and How They Became Powerful Chemical Tools. ChemCatChem 2020; 12:6082-6102. [PMID: 33381242 PMCID: PMC7756376 DOI: 10.1002/cctc.202001107] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/02/2020] [Indexed: 12/20/2022]
Abstract
Enzymatic approaches to challenges in chemical synthesis are increasingly popular and very attractive to industry given their green nature and high efficiency compared to traditional methods. In this historical review we highlight the developments across several fields that were necessary to create the modern field of biocatalysis, with enzyme engineering and directed evolution at its core. We exemplify the modular, incremental, and highly unpredictable nature of scientific discovery, driven by curiosity, and showcase the resulting examples of cutting-edge enzymatic applications in industry.
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Affiliation(s)
- Christian M Heckmann
- School of Chemistry University of Nottingham University Park Nottingham NG7 2RD UK
| | - Francesca Paradisi
- School of Chemistry University of Nottingham University Park Nottingham NG7 2RD UK
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
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9
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Abstract
Our understanding of the human genome has continuously expanded since its draft publication in 2001. Over the years, novel assays have allowed us to progressively overlay layers of knowledge above the raw sequence of A's, T's, G's, and C's. The reference human genome sequence is now a complex knowledge base maintained under the shared stewardship of multiple specialist communities. Its complexity stems from the fact that it is simultaneously a template for transcription, a record of evolution, a vehicle for genetics, and a functional molecule. In short, the human genome serves as a frame of reference at the intersection of a diversity of scientific fields. In recent years, the progressive fall in sequencing costs has given increasing importance to the quality of the human reference genome, as hundreds of thousands of individuals are being sequenced yearly, often for clinical applications. Also, novel sequencing-based assays shed light on novel functions of the genome, especially with respect to gene expression regulation. Keeping the human genome annotation up to date and accurate is therefore an ongoing partnership between reference annotation projects and the greater community worldwide.
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Affiliation(s)
- Daniel R Zerbino
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton CB10 1SD, United Kingdom; , ,
| | - Adam Frankish
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton CB10 1SD, United Kingdom; , ,
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton CB10 1SD, United Kingdom; , ,
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10
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Lant JT, Berg MD, Heinemann IU, Brandl CJ, O'Donoghue P. Pathways to disease from natural variations in human cytoplasmic tRNAs. J Biol Chem 2019; 294:5294-5308. [PMID: 30643023 DOI: 10.1074/jbc.rev118.002982] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Perfectly accurate translation of mRNA into protein is not a prerequisite for life. Resulting from errors in protein synthesis, mistranslation occurs in all cells, including human cells. The human genome encodes >600 tRNA genes, providing both the raw material for genetic variation and a buffer to ensure that resulting translation errors occur at tolerable levels. On the basis of data from the 1000 Genomes Project, we highlight the unanticipated prevalence of mistranslating tRNA variants in the human population and review studies on synthetic and natural tRNA mutations that cause mistranslation or de-regulate protein synthesis. Although mitochondrial tRNA variants are well known to drive human diseases, including developmental disorders, few studies have revealed a role for human cytoplasmic tRNA mutants in disease. In the context of the unexpectedly large number of tRNA variants in the human population, the emerging literature suggests that human diseases may be affected by natural tRNA variants that cause mistranslation or de-regulate tRNA expression and nucleotide modification. This review highlights examples relevant to genetic disorders, cancer, and neurodegeneration in which cytoplasmic tRNA variants directly cause or exacerbate disease and disease-linked phenotypes in cells, animal models, and humans. In the near future, tRNAs may be recognized as useful genetic markers to predict the onset or severity of human disease.
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Affiliation(s)
| | | | | | | | - Patrick O'Donoghue
- From the Departments of Biochemistry and .,Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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11
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Noutahi E, Calderon V, Blanchette M, Lang FB, El-Mabrouk N. CoreTracker: accurate codon reassignment prediction, applied to mitochondrial genomes. Bioinformatics 2018; 33:3331-3339. [PMID: 28655158 DOI: 10.1093/bioinformatics/btx421] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/23/2017] [Indexed: 11/13/2022] Open
Abstract
Motivation Codon reassignments have been reported across all domains of life. With the increasing number of sequenced genomes, the development of systematic approaches for genetic code detection is essential for accurate downstream analyses. Three automated prediction tools exist so far: FACIL, GenDecoder and Bagheera; the last two respectively restricted to metazoan mitochondrial genomes and CUG reassignments in yeast nuclear genomes. These tools can only analyze a single genome at a time and are often not followed by a validation procedure, resulting in a high rate of false positives. Results We present CoreTracker, a new algorithm for the inference of sense-to-sense codon reassignments. CoreTracker identifies potential codon reassignments in a set of related genomes, then uses statistical evaluations and a random forest classifier to predict those that are the most likely to be correct. Predicted reassignments are then validated through a phylogeny-aware step that evaluates the impact of the new genetic code on the protein alignment. Handling simultaneously a set of genomes in a phylogenetic framework, allows tracing back the evolution of each reassignment, which provides information on its underlying mechanism. Applied to metazoan and yeast genomes, CoreTracker significantly outperforms existing methods on both precision and sensitivity. Availability and implementation CoreTracker is written in Python and available at https://github.com/UdeM-LBIT/CoreTracker. Contact mabrouk@iro.umontreal.ca. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Emmanuel Noutahi
- Département d'Informatique et de Recherche Opérationnelle (DIRO), Université de Montréal, Montréal, QC CP 6128, Canada
| | - Virginie Calderon
- Département d'Informatique et de Recherche Opérationnelle (DIRO), Université de Montréal, Montréal, QC CP 6128, Canada
| | - Mathieu Blanchette
- School of Computer Science, McGill University, McConnell Engineering Bldg., Montréal, QC H3A 0E9, Canada
| | - Franz B Lang
- Département de Biochimie, Centre Robert Cedergren, Université de Montréal, Montréal, QC CP 6128, Canada
| | - Nadia El-Mabrouk
- Département d'Informatique et de Recherche Opérationnelle (DIRO), Université de Montréal, Montréal, QC CP 6128, Canada
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12
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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: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [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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13
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Szymanski M, Barciszewski J. The path to the genetic code. Biochim Biophys Acta Gen Subj 2017; 1861:2674-2679. [PMID: 28713021 DOI: 10.1016/j.bbagen.2017.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/03/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
In December of 1966 the last nucleotide triplet in the genetic code has been assigned (Brenner et al., 1967 [1]) thus completing years of studies aimed at deciphering the nature of the relationship between the sequences of genes and proteins. The end product, the table of the genetic code, was a crowning achievement of the quest to unravel the basic mechanisms underlying functioning of all living organisms on the molecular level.
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Affiliation(s)
- Maciej Szymanski
- Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznan, Poland.
| | - Jan Barciszewski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, ul. Noskowskiego 12/14, 61-704 Poznan, Poland.
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14
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Komar AA. The Yin and Yang of codon usage. Hum Mol Genet 2016; 25:R77-R85. [PMID: 27354349 DOI: 10.1093/hmg/ddw207] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 06/24/2016] [Indexed: 01/07/2023] Open
Abstract
The genetic code is degenerate. With the exception of two amino acids (Met and Trp), all other amino acid residues are each encoded by multiple, so-called synonymous codons. Synonymous codons were initially presumed to have entirely equivalent functions, however, the finding that synonymous codons are not present at equal frequencies in genes/genomes suggested that codon choice might have functional implications beyond amino acid coding. The pattern of non-uniform codon use (known as codon usage bias) varies between organisms and represents a unique feature of an organism. Organism-specific codon choice is related to organism-specific differences in populations of cognate tRNAs. This implies that, in a given organism, frequently used codons will be translated more rapidly than infrequently used ones and vice versa A theory of codon-tRNA co-evolution (necessary to balance accurate and efficient protein production) was put forward to explain the existence of codon usage bias. This model suggests that selection favours preferred (frequent) over un-preferred (rare) codons in order to sustain efficient protein production in cells and that a given un-preferred codon will have the same effect on an organism's fitness regardless of its position within an mRNA's open reading frame. However, many recent studies refute this prediction. Un-preferred codons have been found to have important functional roles and their effects appeared to be position-dependent. Synonymous codon usage affects the efficiency/stringency of mRNA decoding, mRNA biogenesis/stability, and protein secretion and folding. This review summarizes recent developments in the field that have identified novel functions of synonymous codons and their usage.
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Affiliation(s)
- Anton A Komar
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio, OH, USA Department of Biochemistry and Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, Ohio, USA Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, OH, USA
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15
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Ling J, O'Donoghue P, Söll D. Genetic code flexibility in microorganisms: novel mechanisms and impact on physiology. Nat Rev Microbiol 2015; 13:707-721. [PMID: 26411296 DOI: 10.1038/nrmicro3568] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The genetic code, initially thought to be universal and immutable, is now known to contain many variations, including biased codon usage, codon reassignment, ambiguous decoding and recoding. As a result of recent advances in the areas of genome sequencing, biochemistry, bioinformatics and structural biology, our understanding of genetic code flexibility has advanced substantially in the past decade. In this Review, we highlight the prevalence, evolution and mechanistic basis of genetic code variations in microorganisms, and we discuss how this flexibility of the genetic code affects microbial physiology.
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Affiliation(s)
- Jiqiang Ling
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - 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
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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16
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Aerni HR, Shifman MA, Rogulina S, O'Donoghue P, Rinehart J. Revealing the amino acid composition of proteins within an expanded genetic code. Nucleic Acids Res 2014; 43:e8. [PMID: 25378305 PMCID: PMC4333366 DOI: 10.1093/nar/gku1087] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The genetic code can be manipulated to reassign codons for the incorporation of non-standard amino acids (NSAA). Deletion of release factor 1 in Escherichia coli enhances translation of UAG (Stop) codons, yet may also extended protein synthesis at natural UAG terminated messenger RNAs. The fidelity of protein synthesis at reassigned UAG codons and the purity of the NSAA containing proteins produced require careful examination. Proteomics would be an ideal tool for these tasks, but conventional proteomic analyses cannot readily identify the extended proteins and accurately discover multiple amino acid (AA) insertions at a single UAG. To address these challenges, we created a new proteomic workflow that enabled the detection of UAG readthrough in native proteins in E. coli strains in which UAG was reassigned to encode phosphoserine. The method also enabled quantitation of NSAA and natural AA incorporation at UAG in a recombinant reporter protein. As a proof-of-principle, we measured the fidelity and purity of the phosphoserine orthogonal translation system (OTS) and used this information to improve its performance. Our results show a surprising diversity of natural AAs at reassigned stop codons. Our method can be used to improve OTSs and to quantify amino acid purity at reassigned codons in organisms with expanded genetic codes.
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Affiliation(s)
- Hans R Aerni
- Department of Cellular & Molecular Physiology, Yale University, New Haven, CT 06520, USA Systems Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Mark A Shifman
- Keck Biotechnology Resource Laboratory, Yale University, New Haven, CT 06511, USA
| | - Svetlana Rogulina
- Department of Cellular & Molecular Physiology, Yale University, New Haven, CT 06520, USA Systems Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Patrick O'Donoghue
- Departments of Biochemistry and Chemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Jesse Rinehart
- Department of Cellular & Molecular Physiology, Yale University, New Haven, CT 06520, USA Systems Biology Institute, Yale University, West Haven, CT 06516, USA
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17
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Brosius J. The persistent contributions of RNA to eukaryotic gen(om)e architecture and cellular function. Cold Spring Harb Perspect Biol 2014; 6:a016089. [PMID: 25081515 DOI: 10.1101/cshperspect.a016089] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Currently, the best scenario for earliest forms of life is based on RNA molecules as they have the proven ability to catalyze enzymatic reactions and harbor genetic information. Evolutionary principles valid today become apparent in such models already. Furthermore, many features of eukaryotic genome architecture might have their origins in an RNA or RNA/protein (RNP) world, including the onset of a further transition, when DNA replaced RNA as the genetic bookkeeper of the cell. Chromosome maintenance, splicing, and regulatory function via RNA may be deeply rooted in the RNA/RNP worlds. Mostly in eukaryotes, conversion from RNA to DNA is still ongoing, which greatly impacts the plasticity of extant genomes. Raw material for novel genes encoding protein or RNA, or parts of genes including regulatory elements that selection can act on, continues to enter the evolutionary lottery.
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Affiliation(s)
- Jürgen Brosius
- Institute of Experimental Pathology (ZMBE), University of Münster, D-48149 Münster, Germany
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18
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Krishnakumar R, Prat L, Aerni HR, Ling J, Merryman C, Glass JI, Rinehart J, Söll D. Transfer RNA misidentification scrambles sense codon recoding. Chembiochem 2013; 14:1967-72. [PMID: 24000185 DOI: 10.1002/cbic.201300444] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Indexed: 12/22/2022]
Abstract
Sense codon recoding is the basis for genetic code expansion with more than two different noncanonical amino acids. It requires an unused (or rarely used) codon, and an orthogonal tRNA synthetase:tRNA pair with the complementary anticodon. The Mycoplasma capricolum genome contains just six CGG arginine codons, without a dedicated tRNA(Arg). We wanted to reassign this codon to pyrrolysine by providing M. capricolum with pyrrolysyl-tRNA synthetase, a synthetic tRNA with a CCG anticodon (tRNA(Pyl)(CCG)), and the genes for pyrrolysine biosynthesis. Here we show that tRNA(Pyl)(CCG) is efficiently recognized by the endogenous arginyl-tRNA synthetase, presumably at the anticodon. Mass spectrometry revealed that in the presence of tRNA(Pyl)(CCG), CGG codons are translated as arginine. This result is not unexpected as most tRNA synthetases use the anticodon as a recognition element. The data suggest that tRNA misidentification by endogenous aminoacyl-tRNA synthetases needs to be overcome for sense codon recoding.
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Affiliation(s)
- Radha Krishnakumar
- Synthetic Biology and Bioenergy, J. Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850 (USA)
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19
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Lengyel P. Memories of a senior scientist: on passing the fiftieth anniversary of the beginning of deciphering the genetic code. Annu Rev Microbiol 2013; 66:27-38. [PMID: 22994487 DOI: 10.1146/annurev-micro-010312-100615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
2011 marked the fiftieth anniversary of breaking the genetic code in 1961. Marshall Nirenberg, the National Institutes of Health (NIH) scientist who was awarded the Nobel Prize in Physiology or Medicine in 1968 for his role in deciphering the code, wrote in 2004 a personal account of his research. The race for the code was a competition between the NIH group and Severo Ochoa's laboratory at New York University (NYU) School of Medicine, where I was a graduate student and conducted many of the experiments. I am now 83 years old. These facts prompt me to recall how I, together with Joe Speyer, an instructor in the Department of Biochemistry at NYU, unexpectedly became involved in deciphering the code, which also became the basis of my PhD thesis. Ochoa won the Nobel Prize in Physiology or Medicine in 1959 for discovering polynucleotide phosphorylase (PNP), the first enzyme found to synthesize RNA in the test tube. The story of how PNP made the deciphering of the code feasible is recalled here.
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Affiliation(s)
- Peter Lengyel
- Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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20
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Genetic Engineering of Mice. Mol Pharmacol 2012. [DOI: 10.1002/9781118451908.ch10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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21
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Zhu P, Bowden P, Zhang D, Marshall JG. Mass spectrometry of peptides and proteins from human blood. MASS SPECTROMETRY REVIEWS 2011; 30:685-732. [PMID: 24737629 DOI: 10.1002/mas.20291] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 12/09/2009] [Accepted: 01/19/2010] [Indexed: 06/03/2023]
Abstract
It is difficult to convey the accelerating rate and growing importance of mass spectrometry applications to human blood proteins and peptides. Mass spectrometry can rapidly detect and identify the ionizable peptides from the proteins in a simple mixture and reveal many of their post-translational modifications. However, blood is a complex mixture that may contain many proteins first expressed in cells and tissues. The complete analysis of blood proteins is a daunting task that will rely on a wide range of disciplines from physics, chemistry, biochemistry, genetics, electromagnetic instrumentation, mathematics and computation. Therefore the comprehensive discovery and analysis of blood proteins will rank among the great technical challenges and require the cumulative sum of many of mankind's scientific achievements together. A variety of methods have been used to fractionate, analyze and identify proteins from blood, each yielding a small piece of the whole and throwing the great size of the task into sharp relief. The approaches attempted to date clearly indicate that enumerating the proteins and peptides of blood can be accomplished. There is no doubt that the mass spectrometry of blood will be crucial to the discovery and analysis of proteins, enzyme activities, and post-translational processes that underlay the mechanisms of disease. At present both discovery and quantification of proteins from blood are commonly reaching sensitivities of ∼1 ng/mL.
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Affiliation(s)
- Peihong Zhu
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3
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22
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Scalable gene synthesis by selective amplification of DNA pools from high-fidelity microchips. Nat Biotechnol 2010; 28:1295-9. [PMID: 21113165 PMCID: PMC3139991 DOI: 10.1038/nbt.1716] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 10/25/2010] [Indexed: 12/14/2022]
Abstract
Development of cheap, high-throughput, and reliable gene synthesis methods will broadly stimulate progress in biology and biotechnology1. Currently, the reliance on column-synthesized oligonucleotides as a source of DNA limits further cost reductions in gene synthesis2. Oligonucleotides from DNA microchips can reduce costs by at least an order of magnitude3,4,5, yet efforts to scale their use have been largely unsuccessful due to the high error rates and complexity of the oligonucleotide mixtures. Here we use high-fidelity DNA microchips, selective oligonucleotide pool amplification, optimized gene assembly protocols, and enzymatic error correction to develop a highly parallel gene synthesis platform. We tested our platform by assembling 47 genes, including 42 challenging therapeutic antibody sequences, encoding a total of ~35 kilo-basepairs of DNA. These assemblies were performed from a complex background containing 13,000 oligonucleotides encoding ~2.5 megabases of DNA, which is at least 50 times larger than previously published attempts.
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23
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Morgan AR, Wells RD, Khorana HG. Studies on polynucleotides, lix. Further codon assignments from amino Acid incorporations directed by ribopolynucleotides containing repeating trinucleotide sequences. Proc Natl Acad Sci U S A 2010; 56:1899-906. [PMID: 16591436 PMCID: PMC220208 DOI: 10.1073/pnas.56.6.1899] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- A R Morgan
- INSTITUTE FOR ENZYME RESEARCH OF THE UNIVERSITY OF WISCONSIN
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24
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Zamir A, Leder P, Elson D. A ribosome-catalyzed reaction between N-formylmethionyl-trna and puromycin. Proc Natl Acad Sci U S A 2010; 56:1794-801. [PMID: 16591422 PMCID: PMC220182 DOI: 10.1073/pnas.56.6.1794] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- A Zamir
- BIOCHEMISTRY SECTION, THE WEIZMANN INSTITUTE OF SCIENCE, REHOVOTH, ISRAEL
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25
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Bowden P, Pendrak V, Zhu P, Marshall JG. Meta sequence analysis of human blood peptides and their parent proteins. J Proteomics 2010; 73:1163-75. [PMID: 20170764 DOI: 10.1016/j.jprot.2010.02.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 01/23/2010] [Accepted: 02/09/2010] [Indexed: 11/19/2022]
Abstract
Sequence analysis of the blood peptides and their qualities will be key to understanding the mechanisms that contribute to error in LC-ESI-MS/MS. Analysis of peptides and their proteins at the level of sequences is much more direct and informative than the comparison of disparate accession numbers. A portable database of all blood peptide and protein sequences with descriptor fields and gene ontology terms might be useful for designing immunological or MRM assays from human blood. The results of twelve studies of human blood peptides and/or proteins identified by LC-MS/MS and correlated against a disparate array of genetic libraries were parsed and matched to proteins from the human ENSEMBL, SwissProt and RefSeq databases by SQL. The reported peptide and protein sequences were organized into an SQL database with full protein sequences and up to five unique peptides in order of prevalence along with the peptide count for each protein. Structured query language or BLAST was used to acquire descriptive information in current databases. Sampling error at the level of peptides is the largest source of disparity between groups. Chi Square analysis of peptide to protein distributions confirmed the significant agreement between groups on identified proteins.
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Affiliation(s)
- Peter Bowden
- Department of Chemistry and Biology, Ryerson University, Toronto, Canada
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26
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Bowden P, Beavis R, Marshall J. Tandem mass spectrometry of human tryptic blood peptides calculated by a statistical algorithm and captured by a relational database with exploration by a general statistical analysis system. J Proteomics 2009; 73:103-11. [PMID: 19703602 DOI: 10.1016/j.jprot.2009.08.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 08/04/2009] [Accepted: 08/17/2009] [Indexed: 01/23/2023]
Abstract
A goodness of fit test may be used to assign tandem mass spectra of peptides to amino acid sequences and to directly calculate the expected probability of mis-identification. The product of the peptide expectation values directly yields the probability that the parent protein has been mis-identified. A relational database could capture the mass spectral data, the best fit results, and permit subsequent calculations by a general statistical analysis system. The many files of the Hupo blood protein data correlated by X!TANDEM against the proteins of ENSEMBL were collected into a relational database. A redundant set of 247,077 proteins and peptides were correlated by X!TANDEM, and that was collapsed to a set of 34,956 peptides from 13,379 distinct proteins. About 6875 distinct proteins were only represented by a single distinct peptide, 2866 proteins showed 2 distinct peptides, and 3454 proteins showed at least three distinct peptides by X!TANDEM. More than 99% of the peptides were associated with proteins that had cumulative expectation values, i.e. probability of false positive identification, of one in one hundred or less. The distribution of peptides per protein from X!TANDEM was significantly different than those expected from random assignment of peptides.
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Affiliation(s)
- Peter Bowden
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3
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27
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Mueller S, Coleman JR, Wimmer E. Putting synthesis into biology: a viral view of genetic engineering through de novo gene and genome synthesis. ACTA ACUST UNITED AC 2009; 16:337-47. [PMID: 19318214 PMCID: PMC2728443 DOI: 10.1016/j.chembiol.2009.03.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 03/09/2009] [Accepted: 03/09/2009] [Indexed: 01/07/2023]
Abstract
The rapid improvements in DNA synthesis technology hold the potential to revolutionize biosciences in the near future. Traditional genetic engineering methods are template dependent and make extensive but laborious use of site-directed mutagenesis to explore the impact of small variations on an existing sequence “theme.” De novo gene and genome synthesis frees the investigator from the restrictions of the pre-existing template and allows for the rational design of any conceivable new sequence theme. Viruses, being among the simplest replicating entities, have been at the forefront of the advancing biosciences since the dawn of molecular biology. Viral genomes, especially those of RNA viruses, are relatively short, often less than 10,000 bases long, making them amenable to whole genome synthesis with the currently available technology. For this reason viruses are once again poised to lead the way in the budding field of synthetic biology—for better or worse.
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Affiliation(s)
- Steffen Mueller
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA.
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28
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Gerstein MB, Bruce C, Rozowsky JS, Zheng D, Du J, Korbel JO, Emanuelsson O, Zhang ZD, Weissman S, Snyder M. What is a gene, post-ENCODE? History and updated definition. Genome Res 2007; 17:669-81. [PMID: 17567988 DOI: 10.1101/gr.6339607] [Citation(s) in RCA: 457] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
While sequencing of the human genome surprised us with how many protein-coding genes there are, it did not fundamentally change our perspective on what a gene is. In contrast, the complex patterns of dispersed regulation and pervasive transcription uncovered by the ENCODE project, together with non-genic conservation and the abundance of noncoding RNA genes, have challenged the notion of the gene. To illustrate this, we review the evolution of operational definitions of a gene over the past century--from the abstract elements of heredity of Mendel and Morgan to the present-day ORFs enumerated in the sequence databanks. We then summarize the current ENCODE findings and provide a computational metaphor for the complexity. Finally, we propose a tentative update to the definition of a gene: A gene is a union of genomic sequences encoding a coherent set of potentially overlapping functional products. Our definition side-steps the complexities of regulation and transcription by removing the former altogether from the definition and arguing that final, functional gene products (rather than intermediate transcripts) should be used to group together entities associated with a single gene. It also manifests how integral the concept of biological function is in defining genes.
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Affiliation(s)
- Mark B Gerstein
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut 06511, USA.
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29
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Affiliation(s)
- Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
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30
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Abstract
Biology today is at a crossroads. The molecular paradigm, which so successfully guided the discipline throughout most of the 20th century, is no longer a reliable guide. Its vision of biology now realized, the molecular paradigm has run its course. Biology, therefore, has a choice to make, between the comfortable path of continuing to follow molecular biology's lead or the more invigorating one of seeking a new and inspiring vision of the living world, one that addresses the major problems in biology that 20th century biology, molecular biology, could not handle and, so, avoided. The former course, though highly productive, is certain to turn biology into an engineering discipline. The latter holds the promise of making biology an even more fundamental science, one that, along with physics, probes and defines the nature of reality. This is a choice between a biology that solely does society's bidding and a biology that is society's teacher.
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Affiliation(s)
- Carl R Woese
- Department of Microbiology, University of Illinois, 601 S. Goodwin, Urbana, IL 61801, USA.
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31
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Agris PF. Decoding the genome: a modified view. Nucleic Acids Res 2004; 32:223-38. [PMID: 14715921 PMCID: PMC384350 DOI: 10.1093/nar/gkh185] [Citation(s) in RCA: 270] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Revised: 12/02/2003] [Accepted: 12/02/2003] [Indexed: 11/12/2022] Open
Abstract
Transfer RNA's role in decoding the genome is critical to the accuracy and efficiency of protein synthesis. Though modified nucleosides were identified in RNA 50 years ago, only recently has their importance to tRNA's ability to decode cognate and wobble codons become apparent. RNA modifications are ubiquitous. To date, some 100 different posttranslational modifications have been identified. Modifications of tRNA are the most extensively investigated; however, many other RNAs have modified nucleosides. The modifications that occur at the first, or wobble position, of tRNA's anticodon and those 3'-adjacent to the anticodon are of particular interest. The tRNAs most affected by individual and combinations of modifications respond to codons in mixed codon boxes where distinction of the third codon base is important for discriminating between the correct cognate or wobble codons and the incorrect near-cognate codons (e.g. AAA/G for lysine versus AAU/C asparagine). In contrast, other modifications expand wobble codon recognition, such as U*U base pairing, for tRNAs that respond to multiple codons of a 4-fold degenerate codon box (e.g. GUU/A/C/G for valine). Whether restricting codon recognition, expanding wobble, enabling translocation, or maintaining the messenger RNA, reading frame modifications appear to reduce anticodon loop dynamics to that accepted by the ribosome. Therefore, we suggest that anticodon stem and loop domain nucleoside modifications allow a limited number of tRNAs to accurately and efficiently decode the 61 amino acid codons by selectively restricting some anticodon-codon interactions and expanding others.
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Affiliation(s)
- Paul F Agris
- Department of Molecular and Structural Biochemistry, 128 Polk Hall, Campus Box 7622, North Carolina State University, Raleigh, NC 27695-7622, USA.
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32
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Southworth DR, Brunelle JL, Green R. EFG-independent translocation of the mRNA:tRNA complex is promoted by modification of the ribosome with thiol-specific reagents. J Mol Biol 2002; 324:611-23. [PMID: 12460565 DOI: 10.1016/s0022-2836(02)01196-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Translation of polyphenylalanine from a polyuridine template by the ribosome in the absence of the elongation factors EFG and EFTu (and the energy derived from GTP hydrolysis) is promoted by modification of the ribosome with thiol-specific reagents such as para-chloromercuribenzoate (pCMB). Here, we examine the translational cycle of modified ribosomes and show that peptide bond formation and tRNA binding are largely unaffected, whereas translocation of the mRNA:tRNA complex is substantially promoted by pCMB modification. The translocation movements that we observe are authentic by multiple criteria including the processivity of translation, accuracy of movement (three-nucleotide) along a defined mRNA template and sensitivity to antibiotics. Characterization of the modified ribosomes reveals that the protein content of the ribosomes is not depleted but that their subunit association properties are severely compromised. These data suggest that molecular targets (ribosomal proteins) in the interface region of the ribosome are critical barriers that influence the translocation of the mRNA:tRNA complex.
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Affiliation(s)
- Daniel R Southworth
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Howard Hughes Medical Institute, Baltimore, MD 21205, USA
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33
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Abstract
This review is occasioned by the fact that the problem of translation, which has simmered on the biological sidelines for the last 40 years, is about to erupt center stage--thanks to the recent spectacular advances in ribosome structure. This most complex, beautiful, and fascinating of cellular mechanisms, the translation apparatus, is also the most important. Translation not only defines gene expression, but it is the sine qua non without which modern (protein-based) cells would not have come into existence. Yet from the start, the problem of translation has been misunderstood--a reflection of the molecular perspective that dominated Biology of the last century. In that the our conception of translation will play a significant role in creating the structure that is 21st century Biology, it is critical that our current (and fundamentally flawed) view of translation be understood for what it is and be reformulated to become an all-embracing perspective about which 21st century Biology can develop. Therefore, the present review is both a retrospective and a plea to biologists to establish a new evolutionary, RNA-World-centered concept of translation. What is needed is an evolutionarily oriented perspective that, first and foremost, focuses on the nature (and origin) of a primitive translation apparatus, the apparatus that transformed an ancient evolutionary era of nucleic acid life, the RNA World, into the world of modern cells.
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Affiliation(s)
- C R Woese
- Department of Microbiology, University of Illinois at Urbana-Champaign, 61801-3709, USA.
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34
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Lien EJ, Das A, Nandy P, Ren S. Physicochemical basis of the universal genetic codes--quantitative analysis. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1997; 48:9-25. [PMID: 9204681 DOI: 10.1007/978-3-0348-8861-5_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Quantitative mathematic models have been developed to correlate the fragment hydrophobicity contribution constants (faa) of 20 amino acids with the physicochemical properties (mu, Hb, and square root of MW) of the four bases (U, A, C, G) of the codons, or those of the anticodons. Using the general equation faa = a mu 1 + b mu 2 + c mu 3 + d square root of MW1 + e square root of MW2 + f square root of MW3 + g Hb1 + h Hb2 + i Hb3 + j, where 1, 2, 3 refer to the first, the second and the third base respectively, correlation coefficient of about 0.82 can be obtained for all 20 amino acids coded by 61 different triplet codes. These correlations are statistically highly significant, even though they do not take into account the involvement of various factors and peptidyl transferases. Furthermore, the reasons for the three stop codons are revealed. The graphic presentation of the codons and the amino acids coded separates the acidic and the basic, the aromatic and the heterocyclic amino acids into different quadrants of an octagon. This is in agreement with the ancient Chinese Ying-Yang theory embedded in the classical I-Ching.
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Affiliation(s)
- E J Lien
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles 90033, USA
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35
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36
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Abstract
tRNAs with inosine (I) in the first position read three codons ending in U, C and A. However, A-ending codons read with I are rarely used. In Escherichia coli, CGA/U/C are all read solely by tRNAICGArg. CGU and CGC are very common codons, but CGA is very rare. Three independent in vivo assays show that translation of CGA is relatively inefficient. In the first, nine tandem CGA cause a strong rho-mediated polar effect on expression of a lacZ reporter gene. The inhibition is made more extreme by a mutation in ribosomal protein S12 (rpsL), which indicates that ribosomal binding by tRNAICGArg is slow and/or unstable in the CGA cluster. The second assay, in which codons are substituted for the regulatory UGA of the RF2 frameshift, confirms that aa-tRNA selection is slow and/or unstable at CGA. In the third assay, CGA is found to be a poor 5' context for amber suppression, which suggests that an A:I base pair in the P site can interfere with translation of a codon in the A site. Two possible errors, frameshifting and premature termination by RF2, are not significant causes for inefficiency at CGA. It is concluded that the A:I pair destabilizes codon:anticodon complexes during two successive ribosomal cycles, and it is suggested that these properties contribute to the rare usage of codons read with the A:I base pair.
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Affiliation(s)
- J F Curran
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109
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37
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CRICK F. Codon—Anticodon Pairing: The Wobble Hypothesis. Mol Biol 1989. [DOI: 10.1016/b978-0-12-131200-8.50026-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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38
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SÖLL D, JONES D, OHTSUKA E, FAULKNER R, LOHRMANN R, HAYATSU H, KHORANA H, CHERAYIL J, HAMPEL A, BOCK ROBERTM. Specificity of sRNA for Recognition of Codons as Studied by the Ribosomal Binding Technique. Mol Biol 1989. [DOI: 10.1016/b978-0-12-131200-8.50027-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
The present paper will focus on the relation between the structure of the table of the genetic code and the evolution of primitive organisms: it will be shown that the organization of the code table according to an optimization principle based on the notion of resistance to errors can provide a criterium for selection. The ordered aspect of the genetic code table makes this result a plausible starting point for studies of the origin and evolution of the genetic code: these could include, besides a more refined optimization principle at the logical level, some effects more directly related to the physico-chemical context, and the construction of realistic models incorporating both aspects.
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Affiliation(s)
- A Figureau
- Institut de Physique Nucléaire (et IN2P3). Université Lyon-I, Villeurbanne, France
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Abstract
The genetic code, which directs the protein biosynthesis, is an information system. Although all its details are not known at present, its essential characteristics are elucidated, as well for the replication or transcription as for the translation of the genetic message. A coherent picture now appears, which reveals the existence of an universal structure, the most fundamental features of which seem to obey some logic. A systematic approach has been devised, which aims to their integration in a theorectical scheme: many features of the code table can thus be interpreted as resulting from a unique principle of best resistance against the effects of mutations. Any group of triplets or amino-acids can be considered along this line. It is more difficult however, to analyse the coexistence of two (or more) different groups. In this work, we propose to extend our optimization principle into a more general one, which includes the notion of information as defined by Shannon. We explore some consequences of this new principle in the most simple models that one can build for the origin and evolution of the genetic code.
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Findley GL, Findley AM, McGlynn SP. Symmetry characteristics of the genetic code. Proc Natl Acad Sci U S A 1982; 79:7061-5. [PMID: 6960365 PMCID: PMC347275 DOI: 10.1073/pnas.79.22.7061] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The symmetric pattern of codon degeneracies is discussed by using empirical arguments processed within a group-theoretic framework. It is reasoned that the genetic code is a relation rather than a mapping, and the symmetry of a relation defined on the codons is investigated. The principal results are (i) a new extraction of the basic symmetry inherent in the standard genetic code; (ii) the unification of the symmetry of ambiguous codon assignments with that of the standard genetic code; and (iii) the primacy of the concept of a biological context as that device which degenerates the code relation to a mapping.
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43
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Towbin H, Elson D. A photoaffinity labelling study of the messenger RNA-binding region of Escherichia coli ribosomes. Nucleic Acids Res 1978; 5:3389-407. [PMID: 360171 PMCID: PMC342257 DOI: 10.1093/nar/5.9.3389] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A photoaffinity labelling study of the messenger RNA-binding region of E. coli ribosomes has been made, using oligoadenylic acids as mRNA analogs. The oligonucleotides, of chain length 6 to 8 and thus several nucleotides longer than oligonucleotides previously employed for this purpose, carried a radioactive photolabile aromatic azide reagent bound covalently to the 3'-terminal ribose moiety. The synthesis of the reagent, p-azidobenzoyl-(3H)-glycylhydrazide, is described. The derivatized oligonucleotides were shown to be functional messengers. They stimulated the binding of the cognate aminoacyl-tRNA, lysyl-tRNA: their binding was reciprocally stimulated by lysyl-tRNA; and they competed with underivatized oligoadenylates for ribosomal binding sites. When the 70 S ribosomal binding complex was irradiated, the photolabile reagent reacted covalently with both RNA and proteins of the 30 S subunit and with tRNA, but not with the 50 S subunit. The 16 S RNA appeared to be labelled at more than one site. Of the proteins, S3 and S5 reacted with the reagent with high specificity; and the possibility was not eliminated that S4 may have been labelled to a minor degree. Functional studies in other laboratories have implicated S3 and S5 in the decoding process, but these proteins were not labelled by any of the previously reported mRNA affinity labelling analogs. The results reported here therefore indicate that S3 and S5 not only affect the decoding process, but are located in the mRNA-binding region of the ribosome, presumably to the 3' side of the decoding site.
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44
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Chao J, Leach M, Karam J. In vivo functional interaction between DNA polymerase and dCMP-hydroxymethylase of bacteriophage T4. J Virol 1977; 24:557-63. [PMID: 562423 PMCID: PMC515967 DOI: 10.1128/jvi.24.2.557-563.1977] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Some mutations in the structural gene for T4 DNA polymerase (gene 43) behave as suppressors of a deficiency in T4 dCMP-hydroxymethylase (gene 42). The suppression appears to involve a functional interaction between the two enzymes at the level of DNA replication. The hydroxymethylase deficiency caused DNA structural abnormalities in replication, and DNA polymerase lesions appeared to partially reverse these abnormalities. The results do not necessarily imply protein-protein interactions between the two enzymes, although both enzymes appear to play roles in controlling the fidelity of phage DNA replication.
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45
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Weiss GB. Translational control of protein synthesis by tRNA unrelated to changes in tRNA concentration. J Mol Evol 1973; 2:199-204. [PMID: 4620076 DOI: 10.1007/bf01654000] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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46
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47
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Rudloff E, Hilse K. Properties of isoaccepting species of lysine tRNA from rabbit reticulocytes in codon recognition and in haemoglobin biosynthesis in vitro. EUROPEAN JOURNAL OF BIOCHEMISTRY 1971; 24:313-20. [PMID: 4945501 DOI: 10.1111/j.1432-1033.1971.tb19688.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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48
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Mitra SK, Ley AN, Smith CJ. Specificity of AAG Codon Recognition by Lysyl Transfer Ribonucleic Acid from Yeast. J Biol Chem 1971. [DOI: 10.1016/s0021-9258(18)61889-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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49
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50
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