51
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McFeely CAL, Dods KK, Patel SS, Hartman MCT. Expansion of the genetic code through reassignment of redundant sense codons using fully modified tRNA. Nucleic Acids Res 2022; 50:11374-11386. [PMID: 36300637 PMCID: PMC9638912 DOI: 10.1093/nar/gkac846] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/09/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022] Open
Abstract
Breaking codon degeneracy for the introduction of non-canonical amino acids offers many opportunities in synthetic biology. Yet, despite the existence of 64 codons, the code has only been expanded to 25 amino acids in vitro. A limiting factor could be the over-reliance on synthetic tRNAs which lack the post-transcriptional modifications that improve translational fidelity. To determine whether modified, wild-type tRNA could improve sense codon reassignment, we developed a new fluorous method for tRNA capture and applied it to the isolation of roughly half of the Escherichia coli tRNA isoacceptors. We then performed codon competition experiments between the five captured wild-type leucyl-tRNAs and their synthetic counterparts, revealing a strong preference for wild-type tRNA in an in vitro translation system. Finally, we compared the ability of wild-type and synthetic leucyl-tRNA to break the degeneracy of the leucine codon box, showing that only captured wild-type tRNAs are discriminated with enough fidelity to accurately split the leucine codon box for the encoding of three separate amino acids. Wild-type tRNAs are therefore enabling reagents for maximizing the reassignment potential of the genetic code.
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Affiliation(s)
- Clinton A L McFeely
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
- Massey Cancer Center, Virginia Commonwealth University , Richmond, VA 23220 , USA
| | - Kara K Dods
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
- Massey Cancer Center, Virginia Commonwealth University , Richmond, VA 23220 , USA
| | - Shivam S Patel
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
| | - Matthew C T Hartman
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
- Massey Cancer Center, Virginia Commonwealth University , Richmond, VA 23220 , USA
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52
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Meng K, Chung CZ, Söll D, Krahn N. Unconventional genetic code systems in archaea. Front Microbiol 2022; 13:1007832. [PMID: 36160229 PMCID: PMC9499178 DOI: 10.3389/fmicb.2022.1007832] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Archaea constitute the third domain of life, distinct from bacteria and eukaryotes given their ability to tolerate extreme environments. To survive these harsh conditions, certain archaeal lineages possess unique genetic code systems to encode either selenocysteine or pyrrolysine, rare amino acids not found in all organisms. Furthermore, archaea utilize alternate tRNA-dependent pathways to biosynthesize and incorporate members of the 20 canonical amino acids. Recent discoveries of new archaeal species have revealed the co-occurrence of these genetic code systems within a single lineage. This review discusses the diverse genetic code systems of archaea, while detailing the associated biochemical elements and molecular mechanisms.
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Affiliation(s)
- Kexin Meng
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States
| | - Christina Z. Chung
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States
| | - Dieter Söll
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States
- Department of Chemistry, Yale University, New Haven, CT, United States
| | - Natalie Krahn
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States
- *Correspondence: Natalie Krahn,
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53
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Byun JK, Vu JA, He SL, Jang JC, Musier-Forsyth K. Plant-exclusive domain of trans-editing enzyme ProXp-ala confers dimerization and enhanced tRNA binding. J Biol Chem 2022; 298:102255. [PMID: 35835222 PMCID: PMC9425024 DOI: 10.1016/j.jbc.2022.102255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/06/2022] [Accepted: 07/08/2022] [Indexed: 11/26/2022] Open
Abstract
Faithful translation of the genetic code is critical for the viability of all living organisms. The trans-editing enzyme ProXp-ala prevents Pro to Ala mutations during translation by hydrolyzing misacylated Ala-tRNAPro that has been synthesized by prolyl-tRNA synthetase. Plant ProXp-ala sequences contain a conserved C-terminal domain (CTD) that is absent in other organisms; the origin, structure, and function of this extra domain are unknown. To characterize the plant-specific CTD, we performed bioinformatics and computational analyses that provided a model consistent with a conserved α-helical structure. We also expressed and purified wildtype Arabidopsis thaliana (At) ProXp-ala in Escherichia coli, as well as variants lacking the CTD or containing only the CTD. Circular dichroism spectroscopy confirmed a loss of α-helical signal intensity upon CTD truncation. Size-exclusion chromatography with multiangle laser-light scattering revealed that wildtype At ProXp-ala was primarily dimeric and CTD truncation abolished dimerization in vitro. Furthermore, bimolecular fluorescence complementation assays in At protoplasts support a role for the CTD in homodimerization in vivo. The deacylation rate of Ala-tRNAPro by At ProXp-ala was also significantly reduced in the absence of the CTD, and kinetic assays indicated that the reduction in activity is primarily due to a tRNA binding defect. Overall, these results broaden our understanding of eukaryotic translational fidelity in the plant kingdom. Our study reveals that the plant-specific CTD plays a significant role in substrate binding and canonical editing function. Through its ability to facilitate protein-protein interactions, we propose the CTD may also provide expanded functional potential for trans-editing enzymes in plants.
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Affiliation(s)
- Jun-Kyu Byun
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - John A Vu
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Siou-Luan He
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA; Department of Horticulture and Crop Science and Center for Applied Plant Sciences, The Ohio State University, Columbus, Ohio, USA
| | - Jyan-Chyun Jang
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA; Department of Horticulture and Crop Science and Center for Applied Plant Sciences, The Ohio State University, Columbus, Ohio, USA.
| | - Karin Musier-Forsyth
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.
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54
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Tittle JM, Schwark DG, Biddle W, Schmitt MA, Fisk JD. Impact of queuosine modification of endogenous E. coli tRNAs on sense codon reassignment. Front Mol Biosci 2022; 9:938114. [PMID: 36120552 PMCID: PMC9471426 DOI: 10.3389/fmolb.2022.938114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
The extent to which alteration of endogenous tRNA modifications may be exploited to improve genetic code expansion efforts has not been broadly investigated. Modifications of tRNAs are strongly conserved evolutionarily, but the vast majority of E. coli tRNA modifications are not essential. We identified queuosine (Q), a non-essential, hypermodified guanosine nucleoside found in position 34 of the anticodons of four E. coli tRNAs as a modification that could potentially be utilized to improve sense codon reassignment. One suggested purpose of queuosine modification is to reduce the preference of tRNAs with guanosine (G) at position 34 of the anticodon for decoding cytosine (C) ending codons over uridine (U) ending codons. We hypothesized that introduced orthogonal translation machinery with adenine (A) at position 34 would reassign U-ending codons more effectively in queuosine-deficient E. coli. We evaluated the ability of introduced orthogonal tRNAs with AUN anticodons to reassign three of the four U-ending codons normally decoded by Q34 endogenous tRNAs: histidine CAU, asparagine AAU, and aspartic acid GAU in the presence and absence of queuosine modification. We found that sense codon reassignment efficiencies in queuosine-deficient strains are slightly improved at Asn AAU, equivalent at His CAU, and less efficient at Asp GAU codons. Utilization of orthogonal pair-directed sense codon reassignment to evaluate competition events that do not occur in the standard genetic code suggests that tRNAs with inosine (I, 6-deaminated A) at position 34 compete much more favorably against G34 tRNAs than Q34 tRNAs. Continued evaluation of sense codon reassignment following targeted alterations to endogenous tRNA modifications has the potential to shed new light on the web of interactions that combine to preserve the fidelity of the genetic code as well as identify opportunities for exploitation in systems with expanded genetic codes.
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55
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Kuhle B, Hirschi M, Doerfel LK, Lander GC, Schimmel P. Structural basis for shape-selective recognition and aminoacylation of a D-armless human mitochondrial tRNA. Nat Commun 2022; 13:5100. [PMID: 36042193 PMCID: PMC9427863 DOI: 10.1038/s41467-022-32544-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/04/2022] [Indexed: 02/05/2023] Open
Abstract
Human mitochondrial gene expression relies on the specific recognition and aminoacylation of mitochondrial tRNAs (mtRNAs) by nuclear-encoded mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs). Despite their essential role in cellular energy homeostasis, strong mutation pressure and genetic drift have led to an unparalleled sequence erosion of animal mtRNAs. The structural and functional consequences of this erosion are not understood. Here, we present cryo-EM structures of the human mitochondrial seryl-tRNA synthetase (mSerRS) in complex with mtRNASer(GCU). These structures reveal a unique mechanism of substrate recognition and aminoacylation. The mtRNASer(GCU) is highly degenerated, having lost the entire D-arm, tertiary core, and stable L-shaped fold that define canonical tRNAs. Instead, mtRNASer(GCU) evolved unique structural innovations, including a radically altered T-arm topology that serves as critical identity determinant in an unusual shape-selective readout mechanism by mSerRS. Our results provide a molecular framework to understand the principles of mito-nuclear co-evolution and specialized mechanisms of tRNA recognition in mammalian mitochondrial gene expression.
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Affiliation(s)
- Bernhard Kuhle
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA.
| | - Marscha Hirschi
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Lili K Doerfel
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA
- The Scripps Florida Research Institute at the University of Florida, Jupiter, FL, 33458, USA
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56
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Uesugi G, Fukuba Y, Yamamoto T, Inaba N, Furukawa H, Yoshizawa S, Tomikawa C, Takai K. Recognition of tRNA
Ile
with a UAU anticodon by isoleucyl‐tRNA synthetase in lactic acid bacteria. FEBS J 2022; 289:4888-4900. [DOI: 10.1111/febs.16389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 12/20/2021] [Accepted: 02/03/2022] [Indexed: 11/27/2022]
Affiliation(s)
- Gakuto Uesugi
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
| | - Yuho Fukuba
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
| | - Takayuki Yamamoto
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
| | - Nozomi Inaba
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
| | - Haruyuki Furukawa
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
| | - Satoko Yoshizawa
- Université Paris‐Saclay ENS Paris‐Saclay CNRS UMR8113 Laboratory of Biology and Applied Pharmacology (LBPA) Gif‐sur‐Yvette France
| | - Chie Tomikawa
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
| | - Kazuyuki Takai
- Department of Materials Science and Biotechnology Graduate School of Science and Engineering Ehime University Matsuyama Japan
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57
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Berg MD, Zhu Y, Loll-Krippleber R, San Luis BJ, Genereaux J, Boone C, Villén J, Brown GW, Brandl CJ. Genetic background and mistranslation frequency determine the impact of mistranslating tRNASerUGG. G3 GENES|GENOMES|GENETICS 2022; 12:6588684. [PMID: 35587152 PMCID: PMC9258585 DOI: 10.1093/g3journal/jkac125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/07/2022] [Indexed: 12/02/2022]
Abstract
Transfer RNA variants increase the frequency of mistranslation, the misincorporation of an amino acid not specified by the “standard” genetic code, to frequencies approaching 10% in yeast and bacteria. Cells cope with these variants by having multiple copies of each tRNA isodecoder and through pathways that deal with proteotoxic stress. In this study, we define the genetic interactions of the gene encoding tRNASerUGG,G26A, which mistranslates serine at proline codons. Using a collection of yeast temperature-sensitive alleles, we identify negative synthetic genetic interactions between the mistranslating tRNA and 109 alleles representing 91 genes, with nearly half of the genes having roles in RNA processing or protein folding and turnover. By regulating tRNA expression, we then compare the strength of the negative genetic interaction for a subset of identified alleles under differing amounts of mistranslation. The frequency of mistranslation correlated with the impact on cell growth for all strains analyzed; however, there were notable differences in the extent of the synthetic interaction at different frequencies of mistranslation depending on the genetic background. For many of the strains, the extent of the negative interaction with tRNASerUGG,G26A was proportional to the frequency of mistranslation or only observed at intermediate or high frequencies. For others, the synthetic interaction was approximately equivalent at all frequencies of mistranslation. As humans contain similar mistranslating tRNAs, these results are important when analyzing the impact of tRNA variants on disease, where both the individual’s genetic background and the expression of the mistranslating tRNA variant need to be considered.
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Affiliation(s)
- Matthew D Berg
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
- Department of Genome Sciences, University of Washington , Seattle, WA 98195, USA
| | - Yanrui Zhu
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
| | - Raphaël Loll-Krippleber
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 3E1, Canada
| | - Bryan-Joseph San Luis
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 1A8, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
| | - Charles Boone
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 1A8, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington , Seattle, WA 98195, USA
| | - Grant W Brown
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, ON M5S 3E1, Canada
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario , London, ON N6A 5C1, Canada
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58
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Kumar P, Bhatnagar A, Sankaranarayanan R. Chiral proofreading during protein biosynthesis and its evolutionary implications. FEBS Lett 2022; 596:1615-1627. [PMID: 35662005 DOI: 10.1002/1873-3468.14419] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/16/2022] [Accepted: 05/29/2022] [Indexed: 11/05/2022]
Abstract
Homochirality of biomacromolecules is a prerequisite for their proper functioning and hence essential for all life forms. This underscores the role of cellular chiral checkpoints in enforcing homochirality during protein biosynthesis. D-aminoacyl-tRNA deacylase (DTD) is an enzyme that performs 'Chirality-based proofreading' to remove D-amino acids mistakenly attached to tRNAs, thus recycling them for further rounds of translation. Paradoxically, owing to its L-chiral rejection mode of action, DTD can remove glycine as well, which is an achiral amino acid. However, this activity is modulated by discriminator base (N73) in tRNA, a unique element that protects the cognate Gly-tRNAGly . Here, we review our recent work showing various aspects of DTD and tRNAGly co-evolution and its key role in maintaining proper translation surveillance in both bacteria and eukaryotes. Moreover, we also discuss two major optimization events on DTD and tRNA that resolved compatibility issues among the archaeal and the bacterial translation apparatuses. Importantly, such optimizations are necessary for the emergence of mitochondria and successful eukaryogenesis.
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Affiliation(s)
- Pradeep Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB campus, Uppal Road, Hyderabad, 500007, India
| | - Akshay Bhatnagar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
| | - Rajan Sankaranarayanan
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB campus, Uppal Road, Hyderabad, 500007, India
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59
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Isaacson JR, Berg MD, Charles B, Jagiello J, Villén J, Brandl CJ, Moehring AJ. A novel mistranslating tRNA model in Drosophila melanogaster has diverse, sexually dimorphic effects. G3 GENES|GENOMES|GENETICS 2022; 12:6526391. [PMID: 35143655 PMCID: PMC9073681 DOI: 10.1093/g3journal/jkac035] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/03/2022] [Indexed: 11/17/2022]
Abstract
Transfer RNAs (tRNAs) are the adaptor molecules required for reading the genetic code and producing proteins. Transfer RNA variants can lead to genome-wide mistranslation, the misincorporation of amino acids not specified by the standard genetic code into nascent proteins. While genome sequencing has identified putative mistranslating transfer RNA variants in human populations, little is known regarding how mistranslation affects multicellular organisms. Here, we create a multicellular model of mistranslation by integrating a serine transfer RNA variant that mistranslates serine for proline (tRNAUGG,G26ASer) into the Drosophila melanogaster genome. We confirm mistranslation via mass spectrometry and find that tRNAUGG,G26ASer misincorporates serine for proline at a frequency of ∼0.6% per codon. tRNAUGG,G26ASer extends development time and decreases the number of flies that reach adulthood. While both sexes of adult flies containing tRNAUGG,G26ASer present with morphological deformities and poor climbing performance, these effects are more pronounced in female flies and the impact on climbing performance is exacerbated by age. This model will enable studies into the synergistic effects of mistranslating transfer RNA variants and disease-causing alleles.
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Affiliation(s)
- Joshua R Isaacson
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Matthew D Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Brendan Charles
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Jessica Jagiello
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Amanda J Moehring
- Department of Biology, The University of Western Ontario, London, ON N6A 5B7, Canada
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60
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Xu C, Tong L, Rao J, Ye Q, Chen Y, Zhang Y, Xu J, Mao X, Meng F, Shen H, Lu Z, Cang X, Fu H, Wang S, Gu W, Lai EY, Guan M, Jiang P, Mao J. Heteroplasmic and homoplasmic m.616T>C in mitochondria tRNAPhe promote isolated chronic kidney disease and hyperuricemia. JCI Insight 2022; 7:157418. [PMID: 35472031 PMCID: PMC9220945 DOI: 10.1172/jci.insight.157418] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 04/22/2022] [Indexed: 11/22/2022] Open
Abstract
Inherited kidney diseases are the fifth most common cause of end-stage renal disease (ESRD). Mitochondrial dysfunction plays a vital role in the progression of inherited kidney diseases, while mitochondrial-transfer RNA (mt-tRNA) variants and their pathogenic contributions to kidney disease remain largely unclear. In this study, we identified the pathogenic mt-tRNAPhe 616T>C mutation in 3 families and documented that m.616T>C showed a high pathogenic threshold, with both heteroplasmy and homoplasmy leading to isolated chronic kidney disease and hyperuricemia without hematuria, proteinuria, or renal cyst formation. Moreover, 1 proband with homoplamic m.616T>C presented ESRD as a child. No symptoms of nervous system evolvement were observed in these families. Lymphoblast cells bearing m.616T>C exhibited swollen mitochondria, underwent active mitophagy, and showed respiratory deficiency, leading to reduced mitochondrial ATP production, diminished membrane potential, and overproduction of mitochondrial ROS. Pathogenic m.616T>C abolished a highly conserved base pair (A31-U39) in the anticodon stem-loop which altered the structure of mt-tRNAPhe, as confirmed by a decreased melting temperature and slower electrophoretic mobility of the mutant tRNA. Furthermore, the unstable structure of mt-tRNAPhe contributed to a shortage of steady-state mt-tRNAPhe and enhanced aminoacylation efficiency, which resulted in impaired mitochondrial RNA translation and a significant decrease in mtDNA–encoded polypeptides. Collectively, these findings provide potentially new insights into the pathogenesis underlying inherited kidney disease caused by mitochondrial variants.
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Affiliation(s)
- Chengxian Xu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Lingxiao Tong
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Jia Rao
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Qing Ye
- Zhejiang Key Laboratory for Neonatal Diseases, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Yuxia Chen
- Department of Rehabilitation Medicine, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Yingying Zhang
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Jie Xu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Xiaoting Mao
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Feilong Meng
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Huijun Shen
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Zhihong Lu
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaohui Cang
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Haidong Fu
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Shugang Wang
- Chigene (Beijing) Translational Medical Research Center, Chigene (Beijing) Translational Medical Research Center, Guangzhou, China
| | - Weiyue Gu
- Chigene (Beijing) Translational Medical Research Center, Chigene (Beijing) Translational Medical Research Center, Guangzhou, China
| | - En Yin Lai
- Department of Physiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Minxin Guan
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Pingping Jiang
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
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61
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Zhang H, Gong X, Zhao Q, Mukai T, Vargas-Rodriguez O, Zhang H, Zhang Y, Wassel P, Amikura K, Maupin-Furlow J, Ren Y, Xu X, Wolf YI, Makarova K, Koonin E, Shen Y, Söll D, Fu X. The tRNA discriminator base defines the mutual orthogonality of two distinct pyrrolysyl-tRNA synthetase/tRNAPyl pairs in the same organism. Nucleic Acids Res 2022; 50:4601-4615. [PMID: 35466371 PMCID: PMC9071458 DOI: 10.1093/nar/gkac271] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/01/2022] [Accepted: 04/07/2022] [Indexed: 12/24/2022] Open
Abstract
Site-specific incorporation of distinct non-canonical amino acids into proteins via genetic code expansion requires mutually orthogonal aminoacyl-tRNA synthetase/tRNA pairs. Pyrrolysyl-tRNA synthetase (PylRS)/tRNAPyl pairs are ideal for genetic code expansion and have been extensively engineered for developing mutually orthogonal pairs. Here, we identify two novel wild-type PylRS/tRNAPyl pairs simultaneously present in the deep-rooted extremely halophilic euryarchaeal methanogen Candidatus Methanohalarchaeum thermophilum HMET1, and show that both pairs are functional in the model halophilic archaeon Haloferax volcanii. These pairs consist of two different PylRS enzymes and two distinct tRNAs with dissimilar discriminator bases. Surprisingly, these two PylRS/tRNAPyl pairs display mutual orthogonality enabled by two unique features, the A73 discriminator base of tRNAPyl2 and a shorter motif 2 loop in PylRS2. In vivo translation experiments show that tRNAPyl2 charging by PylRS2 is defined by the enzyme's shortened motif 2 loop. Finally, we demonstrate that the two HMET1 PylRS/tRNAPyl pairs can simultaneously decode UAG and UAA codons for incorporation of two distinct noncanonical amino acids into protein. This example of a single base change in a tRNA leading to additional coding capacity suggests that the growth of the genetic code is not yet limited by the number of identity elements fitting into the tRNA structure.
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Affiliation(s)
| | | | | | - Takahito Mukai
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Oscar Vargas-Rodriguez
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Huiming Zhang
- BGI-Shenzhen, Shenzhen, 518083, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuxing Zhang
- BGI-Shenzhen, Shenzhen, 518083, China,Sino-Danish College, University of the Chinese Academy of Sciences, Beijing, China
| | - Paul Wassel
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Kazuaki Amikura
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Julie Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA,Genetics Institute, University of Florida, Gainesville, FL 32611, USA
| | - Yan Ren
- BGI-Shenzhen, Shenzhen, 518083, China
| | - Xun Xu
- BGI-Shenzhen, Shenzhen, 518083, China
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Yue Shen
- Correspondence may also be addressed to Yue Shen.
| | - Dieter Söll
- To whom correspondence should be addressed. Tel: +1 203 4326200;
| | - Xian Fu
- Correspondence may also be addressed to Xian Fu.
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62
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Ma Q, Geng Y, Li Q, Cheng C, Zang R, Guo Y, Wu H, Xu C, Zhang M. Comparative mitochondrial genome analyses reveal conserved gene arrangement but massive expansion/contraction in two closely related Exserohilum pathogens. Comput Struct Biotechnol J 2022; 20:1456-1469. [PMID: 35386100 PMCID: PMC8956966 DOI: 10.1016/j.csbj.2022.03.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 01/18/2023] Open
Abstract
Exserohilum turcicum and E. rostratum, two closely related fungal species, are both economically important pathogens but have quite different target hosts (specific to plants and cross-kingdom infection, respectively). In the present study, complete circular mitochondrial genomes of the two Exserohilum species were sequenced and de novo assembled, which mainly comprised the same set of 13 core protein-coding genes (PCGs), two rRNAs, and a certain number of tRNAs and unidentified open reading frames (ORFs). Comparative analyses indicated that these two fungi had significant mitogenomic collinearity and consistent mitochondrial gene arrangement, yet with vastly different mitogenome sizes, 264,948 bp and 64,620 bp, respectively. By contrast with the 17 introns containing 17 intronic ORFs (one-to-one) in the E. rostratum mitogenome, E. turcicum involved far more introns (70) and intronic ORFs (126), which was considered as the main contributing factors of their mitogenome expansion/contraction. Within the generally intron-rich gene cox1, a total of 18 and 10 intron position classes (Pcls) were identified separately in the two mitogenomes. Moreover, 16.16% and 10.85% ratios of intra-mitogenomic repetitive regions were detected in E. turcicum and E. rostratum, respectively. Based on the combined mitochondrial gene dataset, we established a well-supported topology of phylogeny tree of 98 ascomycetes, implying that mitogenomes may act as an effective molecular marker for fungal phylogenetic reconstruction. Our results served as the first report on mitogenomes in the genus Exserohilum, and would have significant implications in understanding the origin, evolution and pathogenic mechanisms of this fungal lineage.
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Affiliation(s)
- Qingzhou Ma
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
| | - Yuehua Geng
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
| | - Qiang Li
- School of Food and Biological Engineering, Chengdu University, Chengdu, China
| | - Chongyang Cheng
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
| | - Rui Zang
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
| | - Yashuang Guo
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
| | - Haiyan Wu
- Analytical Instrument Center, Henan Agricultural University, Zhengzhou, Henan, China
| | - Chao Xu
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
| | - Meng Zhang
- Department of Plant Pathology, Henan Agricultural University, Zhengzhou, Henan, China
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63
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Westhof E, Thornlow B, Chan PP, Lowe TM. Eukaryotic tRNA sequences present conserved and amino acid-specific structural signatures. Nucleic Acids Res 2022; 50:4100-4112. [PMID: 35380696 PMCID: PMC9023262 DOI: 10.1093/nar/gkac222] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 03/16/2022] [Accepted: 03/22/2022] [Indexed: 11/18/2022] Open
Abstract
Metazoan organisms have many tRNA genes responsible for decoding amino acids. The set of all tRNA genes can be grouped in sets of common amino acids and isoacceptor tRNAs that are aminoacylated by corresponding aminoacyl-tRNA synthetases. Analysis of tRNA alignments shows that, despite the high number of tRNA genes, specific tRNA sequence motifs are highly conserved across multicellular eukaryotes. The conservation often extends throughout the isoacceptors and isodecoders with, in some cases, two sets of conserved isodecoders. This study is focused on non-Watson–Crick base pairs in the helical stems, especially GoU pairs. Each of the four helical stems may contain one or more conserved GoU pairs. Some are amino acid specific and could represent identity elements for the cognate aminoacyl tRNA synthetases. Other GoU pairs are found in more than a single amino acid and could be critical for native folding of the tRNAs. Interestingly, some GoU pairs are anticodon-specific, and others are found in phylogenetically-specific clades. Although the distribution of conservation likely reflects a balance between accommodating isotype-specific functions as well as those shared by all tRNAs essential for ribosomal translation, such conservations may indicate the existence of specialized tRNAs for specific translation targets, cellular conditions, or alternative functions.
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Affiliation(s)
- Eric Westhof
- Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, Architecture et Réactivité de l'ARN, CNRS UPR 9002, 2, allée Konrad Roentgen, F-67084 Strasbourg, France
| | - Bryan Thornlow
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA.,UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Patricia P Chan
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA.,UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Todd M Lowe
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA.,UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95064, USA
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64
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Igloi GL. Evolutionary Adjustment of tRNA Identity Rules in Bacillariophyta for Recognition by an Aminoacyl-tRNA Synthetase Adds a Facet to the Origin of Diatoms. J Mol Evol 2022; 90:215-226. [PMID: 35325255 PMCID: PMC8975779 DOI: 10.1007/s00239-022-10053-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/07/2022] [Indexed: 11/26/2022]
Abstract
Error-free protein synthesis relies on the precise recognition by the aminoacyl-tRNA synthetases of their cognate tRNAs in order to attach the corresponding amino acid. A concept of universal tRNA identity elements requires the aminoacyl-tRNA synthetases provided by the genome of an organism to match the identity elements found in the cognate tRNAs in an evolution-independent manner. Identity elements tend to cluster in the tRNA anticodon and acceptor stem regions. However, in the arginine system, in addition to the anticodon, the importance of nucleotide A20 in the tRNA D-loop for cognate enzyme recognition has been a sustained feature for arginyl-tRNA synthetase in archaea, bacteria and in the nuclear-encoded cytosolic form in mammals and plants. However, nuclear-encoded mitochondrial arginyl-tRNA synthetase, which can be distinguished from its cytosolic form by the presence or absence of signature motifs, dispenses with the A20 requirement. An examination of several hundred non-metazoan organisms and their corresponding tRNAArg substrates has confirmed this general concept to a large extent and over numerous phyla. However, some Stramenopiles, and in particular, Diatoms (Bacillariophyta) present a notable exception. Unusually for non-fungal organisms, the nuclear genome encodes tRNAArg isoacceptors with C or U at position 20. In this case one of two nuclear-encoded cytosolic arginyl-tRNA synthetases has evolved to become insensitive to the nature of the D-loop identity element. The other, with a binding pocket that is compatible with tRNAArg-A20 recognition, is targeted to organelles that encode solely such tRNAs.
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Affiliation(s)
- Gabor L Igloi
- Institute of Biology III, University of Freiburg, Freiburg, Germany.
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65
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AAV-delivered suppressor tRNA overcomes a nonsense mutation in mice. Nature 2022; 604:343-348. [PMID: 35322228 PMCID: PMC9446716 DOI: 10.1038/s41586-022-04533-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 01/05/2022] [Indexed: 12/19/2022]
Abstract
Gene therapy is a potentially curative medicine for many currently untreatable diseases, and recombinant adeno-associated virus (rAAV) is the most successful gene delivery vehicle for in vivo applications1-3. However, rAAV-based gene therapy suffers from several limitations, such as constrained DNA cargo size and toxicities caused by non-physiological expression of a transgene4-6. Here we show that rAAV delivery of a suppressor tRNA (rAAV.sup-tRNA) safely and efficiently rescued a genetic disease in a mouse model carrying a nonsense mutation, and effects lasted for more than 6 months after a single treatment. Mechanistically, this was achieved through a synergistic effect of premature stop codon readthrough and inhibition of nonsense-mediated mRNA decay. rAAV.sup-tRNA had a limited effect on global readthrough at normal stop codons and did not perturb endogenous tRNA homeostasis, as determined by ribosome profiling and tRNA sequencing, respectively. By optimizing the AAV capsid and the route of administration, therapeutic efficacy in various target tissues was achieved, including liver, heart, skeletal muscle and brain. This study demonstrates the feasibility of developing a toolbox of AAV-delivered nonsense suppressor tRNAs operating on premature termination codons (AAV-NoSTOP) to rescue pathogenic nonsense mutations and restore gene function under endogenous regulation. As nonsense mutations account for 11% of pathogenic mutations, AAV-NoSTOP can benefit a large number of patients. AAV-NoSTOP obviates the need to deliver a full-length protein-coding gene that may exceed the rAAV packaging limit, elicit adverse immune responses or cause transgene-related toxicities. It therefore represents a valuable addition to gene therapeutics.
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66
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DeBenedictis EA, Söll D, Esvelt KM. Measuring the tolerance of the genetic code to altered codon size. eLife 2022; 11:76941. [PMID: 35293861 PMCID: PMC9094753 DOI: 10.7554/elife.76941] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Translation using four-base codons occurs in both natural and synthetic systems. What constraints contributed to the universal adoption of a triplet codon, rather than quadruplet codon, genetic code? Here, we investigate the tolerance of the Escherichia coli genetic code to tRNA mutations that increase codon size. We found that tRNAs from all 20 canonical isoacceptor classes can be converted to functional quadruplet tRNAs (qtRNAs). Many of these selectively incorporate a single amino acid in response to a specified four-base codon, as confirmed with mass spectrometry. However, efficient quadruplet codon translation often requires multiple tRNA mutations. Moreover, while tRNAs were largely amenable to quadruplet conversion, only nine of the twenty aminoacyl tRNA synthetases tolerate quadruplet anticodons. These may constitute a functional and mutually orthogonal set, but one that sharply limits the chemical alphabet available to a nascent all-quadruplet code. Our results suggest that the triplet codon code was selected because it is simpler and sufficient, not because a quadruplet codon code is unachievable. These data provide a blueprint for synthetic biologists to deliberately engineer an all-quadruplet expanded genetic code.
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Affiliation(s)
- Erika Alden DeBenedictis
- Department of Biological Engineering, Massachusetts Institue of Technology, Cambridge, United States
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Kevin M Esvelt
- Department of Media Arts and Sciences, Massachusetts Institute of Technology, Cambridge, United States
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67
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Jani J, Pappachan A. A review on quality control agents of protein translation - The role of Trans-editing proteins. Int J Biol Macromol 2022; 199:252-263. [PMID: 34995670 DOI: 10.1016/j.ijbiomac.2021.12.176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 12/18/2021] [Accepted: 12/27/2021] [Indexed: 11/16/2022]
Abstract
Translation of RNA to protein is a key feature of cellular life. The fidelity of this process mainly depends on the availability of correctly charged tRNAs. Different domains of tRNA synthetase (aaRS) maintain translation quality by ensuring the proper attachment of particular amino acid with respective tRNA, thus it establishes the rule of genetic code. However occasional errors by aaRS generate mischarged tRNAs, which can become lethal to the cells. Accurate protein synthesis necessitates hydrolysis of mischarged tRNAs. Various cis and trans-editing proteins are identified which recognize these mischarged products and correct them by hydrolysis. Trans-editing proteins are homologs of cis-editing domains of aaRS. The trans-editing proteins work in close association with aaRS, Ef-Tu, and ribosome to prevent global mistranslation and ensures correct charging of tRNA. In this review, we discuss the major trans-editing proteins and compared them with their cis-editing counterparts. We also discuss their structural features, biochemical activity and role in maintaining cellular protein homeostasis.
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Affiliation(s)
- Jaykumar Jani
- School of Life Sciences, Central University of Gujarat, Sector 30, Gandhinagar 382030, Gujarat, India
| | - Anju Pappachan
- School of Life Sciences, Central University of Gujarat, Sector 30, Gandhinagar 382030, Gujarat, India.
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68
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Biddle W, Schwark DG, Schmitt MA, Fisk JD. Directed Evolution Pipeline for the Improvement of Orthogonal Translation Machinery for Genetic Code Expansion at Sense Codons. Front Chem 2022; 10:815788. [PMID: 35252113 PMCID: PMC8891652 DOI: 10.3389/fchem.2022.815788] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/24/2022] [Indexed: 12/30/2022] Open
Abstract
The expansion of the genetic code beyond a single type of noncanonical amino acid (ncAA) is hindered by inefficient machinery for reassigning the meaning of sense codons. A major obstacle to using directed evolution to improve the efficiency of sense codon reassignment is that fractional sense codon reassignments lead to heterogeneous mixtures of full-length proteins with either a ncAA or a natural amino acid incorporated in response to the targeted codon. In stop codon suppression systems, missed incorporations lead to truncated proteins; improvements in activity may be inferred from increased protein yields or the production of downstream reporters. In sense codon reassignment, the heterogeneous proteins produced greatly complicate the development of screens for variants of the orthogonal machinery with improved activity. We describe the use of a previously-reported fluorescence-based screen for sense codon reassignment as the first step in a directed evolution workflow to improve the incorporation of a ncAA in response to the Arg AGG sense codon. We first screened a library with diversity introduced into both the orthogonal Methanocaldococcus jannaschii tyrosyl tRNA anticodon loop and the cognate aminoacyl tRNA synthetase (aaRS) anticodon binding domain for variants that improved incorporation of tyrosine in response to the AGG codon. The most efficient variants produced fluorescent proteins at levels indistinguishable from the E. coli translation machinery decoding tyrosine codons. Mutations to the M. jannaschii aaRS that were found to improve tyrosine incorporation were transplanted onto a M. jannaschii aaRS evolved for the incorporation of para-azidophenylalanine. Improved ncAA incorporation was evident using fluorescence- and mass-based reporters. The described workflow is generalizable and should enable the rapid tailoring of orthogonal machinery capable of activating diverse ncAAs to any sense codon target. We evaluated the selection based improvements of the orthogonal pair in a host genomically engineered for reduced target codon competition. Using this particular system for evaluation of arginine AGG codon reassignment, however, E. coli strains with genomes engineered to remove competing tRNAs did not outperform a standard laboratory E. coli strain in sense codon reassignment.
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69
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Chung CZ, Söll D, Krahn N. Using selenocysteine-specific reporters to screen for efficient tRNA Sec variants. Methods Enzymol 2022; 662:63-93. [PMID: 35101219 DOI: 10.1016/bs.mie.2021.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The unique properties of selenocysteine (Sec) have generated an interest in the scientific community to site-specifically incorporate Sec into a protein of choice. Current technologies have rewired the natural Sec-specific translation factor-dependent selenoprotein biosynthesis pathway by harnessing the canonical elongation factor (EF-Tu) to simplify the requirements for Sec incorporation in Escherichia coli. This strategy is versatile and can be applied to Sec incorporation at any position in a protein of interest. However, selenoprotein production is still limited by yield and serine misincorporation. This protocol outlines a method in E. coli to design and optimize tRNA libraries which can be selected and screened for by the use of Sec-specific intein-based reporters. This provides a fast and simple way to engineer tRNAs with enhanced Sec-incorporation ability.
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Affiliation(s)
- Christina Z Chung
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States
| | - Dieter Söll
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States; Department of Chemistry, Yale University, New Haven, CT, United States.
| | - Natalie Krahn
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, United States
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70
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Lateef OM, Akintubosun MO, Olaoba OT, Samson SO, Adamczyk M. Making Sense of "Nonsense" and More: Challenges and Opportunities in the Genetic Code Expansion, in the World of tRNA Modifications. Int J Mol Sci 2022; 23:938. [PMID: 35055121 PMCID: PMC8779196 DOI: 10.3390/ijms23020938] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 01/09/2023] Open
Abstract
The evolutional development of the RNA translation process that leads to protein synthesis based on naturally occurring amino acids has its continuation via synthetic biology, the so-called rational bioengineering. Genetic code expansion (GCE) explores beyond the natural translational processes to further enhance the structural properties and augment the functionality of a wide range of proteins. Prokaryotic and eukaryotic ribosomal machinery have been proven to accept engineered tRNAs from orthogonal organisms to efficiently incorporate noncanonical amino acids (ncAAs) with rationally designed side chains. These side chains can be reactive or functional groups, which can be extensively utilized in biochemical, biophysical, and cellular studies. Genetic code extension offers the contingency of introducing more than one ncAA into protein through frameshift suppression, multi-site-specific incorporation of ncAAs, thereby increasing the vast number of possible applications. However, different mediating factors reduce the yield and efficiency of ncAA incorporation into synthetic proteins. In this review, we comment on the recent advancements in genetic code expansion to signify the relevance of systems biology in improving ncAA incorporation efficiency. We discuss the emerging impact of tRNA modifications and metabolism in protein design. We also provide examples of the latest successful accomplishments in synthetic protein therapeutics and show how codon expansion has been employed in various scientific and biotechnological applications.
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Affiliation(s)
- Olubodun Michael Lateef
- Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland; (O.M.L.); (M.O.A.); (S.O.S.)
| | | | - Olamide Tosin Olaoba
- Laboratory of Functional and Structural Biochemistry, Federal University of Sao Carlos, Sao Carlos 13565-905, SP, Brazil;
| | - Sunday Ocholi Samson
- Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland; (O.M.L.); (M.O.A.); (S.O.S.)
| | - Malgorzata Adamczyk
- Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland; (O.M.L.); (M.O.A.); (S.O.S.)
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71
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Gamper H, Masuda I, Hou YM. Genome Expansion by tRNA +1 Frameshifting at Quadruplet Codons. J Mol Biol 2022; 434:167440. [PMID: 34995554 PMCID: PMC9643101 DOI: 10.1016/j.jmb.2021.167440] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 12/27/2021] [Accepted: 12/30/2021] [Indexed: 11/29/2022]
Abstract
Inducing tRNA +1 frameshifting to read a quadruplet codon has the potential to incorporate a non-canonical amino acid (ncAA) into the polypeptide chain. While this strategy is attractive for genome expansion in biotechnology and bioengineering endeavors, improving the yield is hampered by a lack of understanding of where the shift can occur in an elongation cycle of protein synthesis. Lacking a clear answer to this question, current efforts have focused on designing +1-frameshifting tRNAs with an extra nucleotide inserted to the anticodon loop for pairing with a quadruplet codon in the aminoacyl-tRNA binding (A) site of the ribosome. However, the designed and evolved +1-frameshifting tRNAs vary broadly in achieving successful genome expansion. Here we summarize recent work on +1-frameshifting tRNAs. We suggest that, rather than engineering the quadruplet anticodon-codon pairing scheme at the ribosome A site, efforts should be made to engineer the pairing scheme at steps after the A site, including the step of the subsequent translocation and the step that stabilizes the pairing scheme in the +1-frame in the peptidyl-tRNA binding (P) site.
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Affiliation(s)
- Howard Gamper
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, USA
| | - Isao Masuda
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, USA
| | - Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, USA.
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72
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Garin S, Levi O, Forrest ME, Antonellis A, Arava YS. Comprehensive characterization of mRNAs associated with yeast cytosolic aminoacyl-tRNA synthetases. RNA Biol 2021; 18:2605-2616. [PMID: 34039240 PMCID: PMC8632134 DOI: 10.1080/15476286.2021.1935116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/18/2021] [Accepted: 05/21/2021] [Indexed: 12/27/2022] Open
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are a conserved family of enzymes with an essential role in protein synthesis: ligating amino acids to cognate tRNA molecules for translation. In addition to their role in tRNA charging, aaRSs have acquired non-canonical functions, including post-transcriptional regulation of mRNA expression. Yet, the extent and mechanisms of these post-transcriptional functions are largely unknown. Herein, we performed a comprehensive transcriptome analysis to define the mRNAs that are associated with almost all aaRSs present in S. cerevisiae cytosol. Nineteen (out of twenty) isogenic strains of GFP-tagged cytosolic aaRSs were subjected to immunoprecipitation with anti-GFP beads along with an untagged control. mRNAs associated with each aaRS were then identified by RNA-seq. The extent of mRNA association varied significantly between aaRSs, from MetRS in which none appeared to be statistically significant, to PheRS that binds hundreds of different mRNAs. Interestingly, many target mRNAs are bound by multiple aaRSs, suggesting co-regulation by this family of enzymes. Gene Ontology analyses for aaRSs with a considerable number of target mRNAs discovered an enrichment for pathways of amino acid metabolism and of ribosome biosynthesis. Furthermore, sequence and structure motif analysis revealed for some aaRSs an enrichment for motifs that resemble the anticodon stem loop of cognate tRNAs. These data suggest that aaRSs coordinate mRNA expression in response to amino acid availability and may utilize RNA elements that mimic their canonical tRNA binding partners.
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Affiliation(s)
- Shahar Garin
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Ofri Levi
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Megan E. Forrest
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Yoav S. Arava
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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73
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Berg MD, Isaacson JR, Cozma E, Genereaux J, Lajoie P, Villén J, Brandl CJ. Regulating Expression of Mistranslating tRNAs by Readthrough RNA Polymerase II Transcription. ACS Synth Biol 2021; 10:3177-3189. [PMID: 34726901 PMCID: PMC8765249 DOI: 10.1021/acssynbio.1c00461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Transfer RNA (tRNA)
variants that alter the genetic code increase
protein diversity and have many applications in synthetic biology.
Since the tRNA variants can cause a loss of proteostasis, regulating
their expression is necessary to achieve high levels of novel protein.
Mechanisms to positively regulate transcription with exogenous activator
proteins like those often used to regulate RNA polymerase II (RNAP
II)-transcribed genes are not applicable to tRNAs as their expression
by RNA polymerase III requires elements internal to the tRNA. Here,
we show that tRNA expression is repressed by overlapping transcription
from an adjacent RNAP II promoter. Regulating the expression of the
RNAP II promoter allows inverse regulation of the tRNA. Placing either
Gal4- or TetR–VP16-activated promoters downstream of a mistranslating
tRNASer variant that misincorporates serine at proline
codons in Saccharomyces cerevisiae allows
mistranslation at a level not otherwise possible because of the toxicity
of the unregulated tRNA. Using this inducible tRNA system, we explore
the proteotoxic effects of mistranslation on yeast cells. High levels
of mistranslation cause cells to arrest in the G1 phase. These cells
are impermeable to propidium iodide, yet growth is not restored upon
repressing tRNA expression. High levels of mistranslation increase
cell size and alter cell morphology. This regulatable tRNA expression
system can be applied to study how native tRNAs and tRNA variants
affect the proteome and other biological processes. Variations of
this inducible tRNA system should be applicable to other eukaryotic
cell types.
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Affiliation(s)
- Matthew D. Berg
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Joshua R. Isaacson
- Department of Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ecaterina Cozma
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick Lajoie
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Christopher J. Brandl
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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74
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Lant JT, Kiri R, Duennwald ML, O'Donoghue P. Formation and persistence of polyglutamine aggregates in mistranslating cells. Nucleic Acids Res 2021; 49:11883-11899. [PMID: 34718744 PMCID: PMC8599886 DOI: 10.1093/nar/gkab898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/03/2021] [Accepted: 09/20/2021] [Indexed: 12/17/2022] Open
Abstract
In neurodegenerative diseases, including pathologies with well-known causative alleles, genetic factors that modify severity or age of onset are not entirely understood. We recently documented the unexpected prevalence of transfer RNA (tRNA) mutants in the human population, including variants that cause amino acid mis-incorporation. We hypothesized that a mistranslating tRNA will exacerbate toxicity and modify the molecular pathology of Huntington's disease-causing alleles. We characterized a tRNAPro mutant that mistranslates proline codons with alanine, and tRNASer mutants, including a tRNASerAGA G35A variant with a phenylalanine anticodon (tRNASerAAA) found in ∼2% of the population. The tRNAPro mutant caused synthetic toxicity with a deleterious huntingtin poly-glutamine (polyQ) allele in neuronal cells. The tRNASerAAA variant showed synthetic toxicity with proteasome inhibition but did not enhance toxicity of the huntingtin allele. Cells mistranslating phenylalanine or proline codons with serine had significantly reduced rates of protein synthesis. Mistranslating cells were slow but effective in forming insoluble polyQ aggregates, defective in protein and aggregate degradation, and resistant to the neuroprotective integrated stress response inhibitor (ISRIB). Our findings identify mistranslating tRNA variants as genetic factors that slow protein aggregation kinetics, inhibit aggregate clearance, and increase drug resistance in cellular models of neurodegenerative disease.
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Affiliation(s)
- Jeremy T Lant
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Rashmi Kiri
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Martin L Duennwald
- Department of Anatomy & Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick O'Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada.,Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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75
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Shulgina Y, Eddy SR. A computational screen for alternative genetic codes in over 250,000 genomes. eLife 2021; 10:71402. [PMID: 34751130 PMCID: PMC8629427 DOI: 10.7554/elife.71402] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/26/2021] [Indexed: 11/25/2022] Open
Abstract
The genetic code has been proposed to be a ‘frozen accident,’ but the discovery of alternative genetic codes over the past four decades has shown that it can evolve to some degree. Since most examples were found anecdotally, it is difficult to draw general conclusions about the evolutionary trajectories of codon reassignment and why some codons are affected more frequently. To fill in the diversity of genetic codes, we developed Codetta, a computational method to predict the amino acid decoding of each codon from nucleotide sequence data. We surveyed the genetic code usage of over 250,000 bacterial and archaeal genome sequences in GenBank and discovered five new reassignments of arginine codons (AGG, CGA, and CGG), representing the first sense codon changes in bacteria. In a clade of uncultivated Bacilli, the reassignment of AGG to become the dominant methionine codon likely evolved by a change in the amino acid charging of an arginine tRNA. The reassignments of CGA and/or CGG were found in genomes with low GC content, an evolutionary force that likely helped drive these codons to low frequency and enable their reassignment. All life forms rely on a ‘code’ to translate their genetic information into proteins. This code relies on limited permutations of three nucleotides – the building blocks that form DNA and other types of genetic information. Each ‘triplet’ of nucleotides – or codon – encodes a specific amino acid, the basic component of proteins. Reading the sequence of codons in the right order will let the cell know which amino acid to assemble next on a growing protein. For instance, the codon CGG – formed of the nucleotides guanine (G) and cytosine (C) – codes for the amino acid arginine. From bacteria to humans, most life forms rely on the same genetic code. Yet certain organisms have evolved to use slightly different codes, where one or several codons have an altered meaning. To better understand how alternative genetic codes have evolved, Shulgina and Eddy set out to find more organisms featuring these altered codons, creating a new software called Codetta that can analyze the genome of a microorganism and predict the genetic code it uses. Codetta was then used to sift through the genetic information of 250,000 microorganisms. This was made possible by the sequencing, in recent years, of the genomes of hundreds of thousands of bacteria and other microorganisms – including many never studied before. These analyses revealed five groups of bacteria with alternative genetic codes, all of which had changes in the codons that code for arginine. Amongst these, four had genomes with a low proportion of guanine and cytosine nucleotides. This may have made some guanine and cytosine-rich arginine codons very rare in these organisms and, therefore, easier to be reassigned to encode another amino acid. The work by Shulgina and Eddy demonstrates that Codetta is a new, useful tool that scientists can use to understand how genetic codes evolve. In addition, it can also help to ensure the accuracy of widely used protein databases, which assume which genetic code organisms use to predict protein sequences from their genomes.
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Affiliation(s)
| | - Sean R Eddy
- Molecular & Cellular Biology, Harvard University, Cambridge, United States
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76
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Horikoshi T, Noguchi H, Umehara T, Mutsuro-Aoki H, Kurihara R, Noguchi R, Hashimoto T, Watanabe Y, Ando T, Kamata K, Park SY, Tamura K. Crystal structure of Nanoarchaeum equitans tyrosyl-tRNA synthetase and its aminoacylation activity toward tRNA Tyr with an extra guanosine residue at the 5'-terminus. Biochem Biophys Res Commun 2021; 575:90-95. [PMID: 34461441 DOI: 10.1016/j.bbrc.2021.08.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/24/2022]
Abstract
tRNATyr of Nanoarchaeum equitans has a remarkable feature with an extra guanosine residue at the 5'-terminus. However, the N. equitans tRNATyr mutant without extra guanosine at the 5'-end was tyrosylated by tyrosyl-tRNA synthase (TyrRS). We solved the crystal structure of N. equitans TyrRS at 2.80 Å resolution. By comparing the present solved structure with the complex structures TyrRS with tRNATyr of Thermus thermophilus and Methanocaldococcus jannaschii, an arginine substitution mutant of N. equitans TyrRS at Ile200 (I200R), which is the putative closest candidate to the 5'-phosphate of C1 of N. equitans tRNATyr, was prepared. The I200R mutant tyrosylated not only wild-type tRNATyr but also the tRNA without the G-1 residue. Further tyrosylation analysis revealed that the second base of the anticodon (U35), discriminator base (A73), and C1:G72 base pair are strong recognition sites.
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Affiliation(s)
- Tatsuya Horikoshi
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiroki Noguchi
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan
| | - Takuya Umehara
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiromi Mutsuro-Aoki
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Ryodai Kurihara
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Ryohei Noguchi
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Takahiro Hashimoto
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Yuki Watanabe
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Tadashi Ando
- Department of Applied Electronics, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan; Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Kenichi Kamata
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan
| | - Sam-Yong Park
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan
| | - Koji Tamura
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan; Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
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77
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Kim S, Yi H, Kim YT, Lee HS. Engineering Translation Components for Genetic Code Expansion. J Mol Biol 2021; 434:167302. [PMID: 34673113 DOI: 10.1016/j.jmb.2021.167302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/26/2021] [Accepted: 10/05/2021] [Indexed: 12/18/2022]
Abstract
The expansion of the genetic code consisting of four bases and 20 amino acids into diverse building blocks has been an exciting topic in synthetic biology. Many biochemical components are involved in gene expression; therefore, adding a new component to the genetic code requires engineering many other components that interact with it. Genetic code expansion has advanced significantly for the last two decades with the engineering of several components involved in protein synthesis. These components include tRNA/aminoacyl-tRNA synthetase, new codons, ribosomes, and elongation factor Tu. In addition, biosynthesis and enhanced uptake of non-canonical amino acids have been attempted and have made meaningful progress. This review discusses the efforts to engineer these translation components, to improve the genetic code expansion technology.
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Affiliation(s)
- Sooin Kim
- Department of Chemistry, Sogang University, 35 Baekbeomro Mapogu, Seoul 04107, Republic of Korea
| | - Hanbin Yi
- Department of Chemistry, Sogang University, 35 Baekbeomro Mapogu, Seoul 04107, Republic of Korea
| | - Yurie T Kim
- Department of Chemistry, Sogang University, 35 Baekbeomro Mapogu, Seoul 04107, Republic of Korea
| | - Hyun Soo Lee
- Department of Chemistry, Sogang University, 35 Baekbeomro Mapogu, Seoul 04107, Republic of Korea.
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78
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DeBenedictis EA, Carver GD, Chung CZ, Söll D, Badran AH. Multiplex suppression of four quadruplet codons via tRNA directed evolution. Nat Commun 2021; 12:5706. [PMID: 34588441 PMCID: PMC8481270 DOI: 10.1038/s41467-021-25948-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 09/10/2021] [Indexed: 11/20/2022] Open
Abstract
Genetic code expansion technologies supplement the natural codon repertoire with assignable variants in vivo, but are often limited by heterologous translational components and low suppression efficiencies. Here, we explore engineered Escherichia coli tRNAs supporting quadruplet codon translation by first developing a library-cross-library selection to nominate quadruplet codon-anticodon pairs. We extend our findings using a phage-assisted continuous evolution strategy for quadruplet-decoding tRNA evolution (qtRNA-PACE) that improved quadruplet codon translation efficiencies up to 80-fold. Evolved qtRNAs appear to maintain codon-anticodon base pairing, are typically aminoacylated by their cognate tRNA synthetases, and enable processive translation of adjacent quadruplet codons. Using these components, we showcase the multiplexed decoding of up to four unique quadruplet codons by their corresponding qtRNAs in a single reporter. Cumulatively, our findings highlight how E. coli tRNAs can be engineered, evolved, and combined to decode quadruplet codons, portending future developments towards an exclusively quadruplet codon translation system.
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Affiliation(s)
- Erika A DeBenedictis
- The Broad Institute of MIT & Harvard, Cambridge, MA, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Christina Z Chung
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Ahmed H Badran
- The Broad Institute of MIT & Harvard, Cambridge, MA, USA.
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA.
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79
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Berg MD, Zhu Y, Ruiz BY, Loll-Krippleber R, Isaacson J, San Luis BJ, Genereaux J, Boone C, Villén J, Brown GW, Brandl CJ. The amino acid substitution affects cellular response to mistranslation. G3-GENES GENOMES GENETICS 2021; 11:6310018. [PMID: 34568909 PMCID: PMC8473984 DOI: 10.1093/g3journal/jkab218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/24/2023]
Abstract
Mistranslation, the misincorporation of an amino acid not specified by the "standard" genetic code, occurs in all organisms. tRNA variants that increase mistranslation arise spontaneously and engineered tRNAs can achieve mistranslation frequencies approaching 10% in yeast and bacteria. Interestingly, human genomes contain tRNA variants with the potential to mistranslate. Cells cope with increased mistranslation through multiple mechanisms, though high levels cause proteotoxic stress. The goal of this study was to compare the genetic interactions and the impact on transcriptome and cellular growth of two tRNA variants that mistranslate at a similar frequency but create different amino acid substitutions in Saccharomyces cerevisiae. One tRNA variant inserts alanine at proline codons whereas the other inserts serine for arginine. Both tRNAs decreased growth rate, with the effect being greater for arginine to serine than for proline to alanine. The tRNA that substituted serine for arginine resulted in a heat shock response. In contrast, heat shock response was minimal for proline to alanine substitution. Further demonstrating the significance of the amino acid substitution, transcriptome analysis identified unique up- and down-regulated genes in response to each mistranslating tRNA. Number and extent of negative synthetic genetic interactions also differed depending upon type of mistranslation. Based on the unique responses observed for these mistranslating tRNAs, we predict that the potential of mistranslation to exacerbate diseases caused by proteotoxic stress depends on the tRNA variant. Furthermore, based on their unique transcriptomes and genetic interactions, different naturally occurring mistranslating tRNAs have the potential to negatively influence specific diseases.
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Affiliation(s)
- Matthew D Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada.,Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Yanrui Zhu
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Bianca Y Ruiz
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Raphaël Loll-Krippleber
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Joshua Isaacson
- Department of Biology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Bryan-Joseph San Luis
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Charles Boone
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Grant W Brown
- Department of Biochemistry, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S, Canada
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 3K7, Canada
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80
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Chan PP, Lin BY, Mak AJ, Lowe TM. tRNAscan-SE 2.0: improved detection and functional classification of transfer RNA genes. Nucleic Acids Res 2021; 49:9077-9096. [PMID: 34417604 PMCID: PMC8450103 DOI: 10.1093/nar/gkab688] [Citation(s) in RCA: 471] [Impact Index Per Article: 157.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 12/17/2022] Open
Abstract
tRNAscan-SE has been widely used for transfer RNA (tRNA) gene prediction for over twenty years, developed just as the first genomes were decoded. With the massive increase in quantity and phylogenetic diversity of genomes, the accurate detection and functional prediction of tRNAs has become more challenging. Utilizing a vastly larger training set, we created nearly one hundred specialized isotype- and clade-specific models, greatly improving tRNAscan-SE’s ability to identify and classify both typical and atypical tRNAs. We employ a new comparative multi-model strategy where predicted tRNAs are scored against a full set of isotype-specific covariance models, allowing functional prediction based on both the anticodon and the highest-scoring isotype model. Comparative model scoring has also enhanced the program's ability to detect tRNA-derived SINEs and other likely pseudogenes. For the first time, tRNAscan-SE also includes fast and highly accurate detection of mitochondrial tRNAs using newly developed models. Overall, tRNA detection sensitivity and specificity is improved for all isotypes, particularly those utilizing specialized models for selenocysteine and the three subtypes of tRNA genes encoding a CAU anticodon. These enhancements will provide researchers with more accurate and detailed tRNA annotation for a wider variety of tRNAs, and may direct attention to tRNAs with novel traits.
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Affiliation(s)
- Patricia P Chan
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California, Santa Cruz, CA 95064, USA
| | - Brian Y Lin
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California, Santa Cruz, CA 95064, USA
| | - Allysia J Mak
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California, Santa Cruz, CA 95064, USA
| | - Todd M Lowe
- Department of Biomolecular Engineering, Baskin School of Engineering, University of California, Santa Cruz, CA 95064, USA
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81
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The Combinatorial Fusion Cascade to Generate the Standard Genetic Code. Life (Basel) 2021; 11:life11090975. [PMID: 34575125 PMCID: PMC8467831 DOI: 10.3390/life11090975] [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] [Received: 09/02/2021] [Revised: 09/14/2021] [Accepted: 09/14/2021] [Indexed: 11/17/2022] Open
Abstract
Combinatorial fusion cascade was proposed as a transition stage between prebiotic chemistry and early forms of life. The combinatorial fusion cascade consists of three stages: eight initial complimentary pairs of amino acids, four protocodes, and the standard genetic code. The initial complimentary pairs and the protocodes are divided into dominant and recessive entities. The transitions between these stages obey the same combinatorial fusion rules for all amino acids. The combinatorial fusion cascade mathematically describes the codon assignments in the standard genetic code. It explains the availability of amino acids with the even and odd numbers of codons, the appearance of stop codons, inclusion of novel canonical amino acids, exceptional high numbers of codons for amino acids arginine, leucine, and serine, and the temporal order of amino acid inclusion into the genetic code. The temporal order of amino acids within the cascade is congruent with the consensus temporal order previously derived from the similarities between the available hypotheses. The control over the combinatorial fusion cascades would open the road for a novel technology to develop artificial microorganisms.
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82
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Kato Y. An Unnatural Amino Acid-Regulated Growth Controller Based on Informational Disturbance. Life (Basel) 2021; 11:life11090920. [PMID: 34575069 PMCID: PMC8467816 DOI: 10.3390/life11090920] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/26/2021] [Accepted: 09/01/2021] [Indexed: 01/10/2023] Open
Abstract
We designed a novel growth controller regulated by feeding of an unnatural amino acid, Nε-benzyloxycarbonyl-l-lysine (ZK), using a specific incorporation system at a sense codon. This system is constructed by a pair of modified pyrrolisyl-tRNA synthetase (PylRS) and its cognate tRNA (tRNApyl). Although ZK is non-toxic for normal organisms, the growth of Escherichia coli carrying the ZK incorporation system was inhibited in a ZK concentration-dependent manner without causing rapid bacterial death, presumably due to generation of non-functional or toxic proteins. The extent of growth inhibition strongly depended on the anticodon sequence of the tRNApyl gene. Taking advantage of the low selectivity of PylRS for tRNApyl anticodons, we experimentally determined the most effective anticodon sequence among all 64 nucleotide sequences in the anticodon region of tRNApyl gene. The results suggest that the ZK-regulated growth controller is a simple, target-specific, environmental noise-resistant and titratable system. This technique may be applicable to a wide variety of organisms because the growth inhibitory effects are caused by "informational disturbance", in which the highly conserved system for transmission of information from DNA to proteins is perturbed.
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Affiliation(s)
- Yusuke Kato
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Oowashi 1-2, Tsukuba 305-8634, Ibaraki, Japan
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83
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Bacterial translation machinery for deliberate mistranslation of the genetic code. Proc Natl Acad Sci U S A 2021; 118:2110797118. [PMID: 34413202 DOI: 10.1073/pnas.2110797118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Inaccurate expression of the genetic code, also known as mistranslation, is an emerging paradigm in microbial studies. Growing evidence suggests that many microbial pathogens can deliberately mistranslate their genetic code to help invade a host or evade host immune responses. However, discovering different capacities for deliberate mistranslation remains a challenge because each group of pathogens typically employs a unique mistranslation mechanism. In this study, we address this problem by studying duplicated genes of aminoacyl-transfer RNA (tRNA) synthetases. Using bacterial prolyl-tRNA synthetase (ProRS) genes as an example, we identify an anomalous ProRS isoform, ProRSx, and a corresponding tRNA, tRNAProA, that are predominately found in plant pathogens from Streptomyces species. We then show that tRNAProA has an unusual hybrid structure that allows this tRNA to mistranslate alanine codons as proline. Finally, we provide biochemical, genetic, and mass spectrometric evidence that cells which express ProRSx and tRNAProA can translate GCU alanine codons as both alanine and proline. This dual use of alanine codons creates a hidden proteome diversity due to stochastic Ala→Pro mutations in protein sequences. Thus, we show that important plant pathogens are equipped with a tool to alter the identity of their sense codons. This finding reveals the initial example of a natural tRNA synthetase/tRNA pair for dedicated mistranslation of sense codons.
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84
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Warren JM, Salinas-Giegé T, Triant DA, Taylor DR, Drouard L, Sloan DB. Rapid shifts in mitochondrial tRNA import in a plant lineage with extensive mitochondrial tRNA gene loss. Mol Biol Evol 2021; 38:5735-5751. [PMID: 34436590 PMCID: PMC8662596 DOI: 10.1093/molbev/msab255] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In most eukaryotes, transfer RNAs (tRNAs) are one of the very few classes of genes remaining in the mitochondrial genome, but some mitochondria have lost these vestiges of their prokaryotic ancestry. Sequencing of mitogenomes from the flowering plant genus Silene previously revealed a large range in tRNA gene content, suggesting rapid and ongoing gene loss/replacement. Here, we use this system to test longstanding hypotheses about how mitochondrial tRNA genes are replaced by importing nuclear-encoded tRNAs. We traced the evolutionary history of these gene loss events by sequencing mitochondrial genomes from key outgroups (Agrostemma githago and Silene [=Lychnis] chalcedonica). We then performed the first global sequencing of purified plant mitochondrial tRNA populations to characterize the expression of mitochondrial-encoded tRNAs and the identity of imported nuclear-encoded tRNAs. We also confirmed the utility of high-throughput sequencing methods for the detection of tRNA import by sequencing mitochondrial tRNA populations in a species (Solanum tuberosum) with known tRNA trafficking patterns. Mitochondrial tRNA sequencing in Silene revealed substantial shifts in the abundance of some nuclear-encoded tRNAs in conjunction with their recent history of mt-tRNA gene loss and surprising cases where tRNAs with anticodons still encoded in the mitochondrial genome also appeared to be imported. These data suggest that nuclear-encoded counterparts are likely replacing mitochondrial tRNAs even in systems with recent mitochondrial tRNA gene loss, and the redundant import of a nuclear-encoded tRNA may provide a mechanism for functional replacement between translation systems separated by billions of years of evolutionary divergence.
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Affiliation(s)
- Jessica M Warren
- Department of Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA
| | - Thalia Salinas-Giegé
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, Strasbourg, F-67084, France
| | - Deborah A Triant
- Department of Biochemistry & Molecular Genetics, University of Virginia, Charlottesville, VA, 22908, USA
| | - Douglas R Taylor
- Department of Biology, University of Virginia, Charlottesville, VA, 22904-4328, USA
| | - Laurence Drouard
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, Strasbourg, F-67084, France
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA
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85
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Fagan SG, Helm M, Prehn JHM. tRNA-derived fragments: A new class of non-coding RNA with key roles in nervous system function and dysfunction. Prog Neurobiol 2021; 205:102118. [PMID: 34245849 DOI: 10.1016/j.pneurobio.2021.102118] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/30/2021] [Accepted: 07/06/2021] [Indexed: 01/12/2023]
Abstract
tRNA-derived small RNAs (tsRNA) are a recently identified family of non-coding RNA that have been associated with a variety of cellular functions including the regulation of protein translation and gene expression. Recent sequencing and bioinformatic studies have identified the broad spectrum of tsRNA in the nervous system and demonstrated that this new class of non-coding RNA is produced from tRNA by specific cleavage events catalysed by ribonucleases such as angiogenin and dicer. Evidence is also accumulating that production of tsRNA is increased during disease processes where they regulate stress responses, proteostasis, and neuronal survival. Mutations to tRNA cleaving and modifying enzymes have been implicated in several neurodegenerative disorders, and tsRNA levels in the blood are advancing as biomarkers for neurological disease. In this review we summarize the physiological importance of tsRNA in the central nervous system and their relevance to neurological disease.
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Affiliation(s)
- Steven G Fagan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, St. Stephen'S Green, Dublin 2, Ireland; SFI FutureNeuro Research Centre, Royal College of Surgeons in Ireland, St. Stephen's Green, Dublin 2, Ireland
| | - Mark Helm
- Institute of Pharmaceutical and Biomedical Sciences - IPBS, Johannes Gutenberg-University, 55128, Mainz, Germany
| | - Jochen H M Prehn
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, St. Stephen'S Green, Dublin 2, Ireland; SFI FutureNeuro Research Centre, Royal College of Surgeons in Ireland, St. Stephen's Green, Dublin 2, Ireland.
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86
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Albers S, Beckert B, Matthies MC, Mandava CS, Schuster R, Seuring C, Riedner M, Sanyal S, Torda AE, Wilson DN, Ignatova Z. Repurposing tRNAs for nonsense suppression. Nat Commun 2021; 12:3850. [PMID: 34158503 PMCID: PMC8219837 DOI: 10.1038/s41467-021-24076-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 06/01/2021] [Indexed: 02/06/2023] Open
Abstract
Three stop codons (UAA, UAG and UGA) terminate protein synthesis and are almost exclusively recognized by release factors. Here, we design de novo transfer RNAs (tRNAs) that efficiently decode UGA stop codons in Escherichia coli. The tRNA designs harness various functionally conserved aspects of sense-codon decoding tRNAs. Optimization within the TΨC-stem to stabilize binding to the elongation factor, displays the most potent effect in enhancing suppression activity. We determine the structure of the ribosome in a complex with the designed tRNA bound to a UGA stop codon in the A site at 2.9 Å resolution. In the context of the suppressor tRNA, the conformation of the UGA codon resembles that of a sense-codon rather than when canonical translation termination release factors are bound, suggesting conformational flexibility of the stop codons dependent on the nature of the A-site ligand. The systematic analysis, combined with structural insights, provides a rationale for targeted repurposing of tRNAs to correct devastating nonsense mutations that introduce a premature stop codon.
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Affiliation(s)
- Suki Albers
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Bertrand Beckert
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Marco C. Matthies
- grid.9026.d0000 0001 2287 2617Center for Bioinformatics, University of Hamburg, Hamburg, Germany
| | - Chandra Sekhar Mandava
- grid.8993.b0000 0004 1936 9457Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Raphael Schuster
- grid.9026.d0000 0001 2287 2617Institute of Organic Chemistry, University of Hamburg, Hamburg, Germany
| | | | - Maria Riedner
- grid.9026.d0000 0001 2287 2617Institute of Organic Chemistry, University of Hamburg, Hamburg, Germany
| | - Suparna Sanyal
- grid.8993.b0000 0004 1936 9457Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Andrew E. Torda
- grid.9026.d0000 0001 2287 2617Center for Bioinformatics, University of Hamburg, Hamburg, Germany
| | - Daniel N. Wilson
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Zoya Ignatova
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
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87
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Sweeney BA, Hoksza D, Nawrocki EP, Ribas CE, Madeira F, Cannone JJ, Gutell R, Maddala A, Meade CD, Williams LD, Petrov AS, Chan PP, Lowe TM, Finn RD, Petrov AI. R2DT is a framework for predicting and visualising RNA secondary structure using templates. Nat Commun 2021; 12:3494. [PMID: 34108470 PMCID: PMC8190129 DOI: 10.1038/s41467-021-23555-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 05/04/2021] [Indexed: 02/05/2023] Open
Abstract
Non-coding RNAs (ncRNA) are essential for all life, and their functions often depend on their secondary (2D) and tertiary structure. Despite the abundance of software for the visualisation of ncRNAs, few automatically generate consistent and recognisable 2D layouts, which makes it challenging for users to construct, compare and analyse structures. Here, we present R2DT, a method for predicting and visualising a wide range of RNA structures in standardised layouts. R2DT is based on a library of 3,647 templates representing the majority of known structured RNAs. R2DT has been applied to ncRNA sequences from the RNAcentral database and produced >13 million diagrams, creating the world's largest RNA 2D structure dataset. The software is amenable to community expansion, and is freely available at https://github.com/rnacentral/R2DT and a web server is found at https://rnacentral.org/r2dt .
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Affiliation(s)
- Blake A Sweeney
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - David Hoksza
- Department of Software Engineering, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Eric P Nawrocki
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Carlos Eduardo Ribas
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - Fábio Madeira
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - Jamie J Cannone
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Robin Gutell
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Aparna Maddala
- School of Chemistry and Biochemistry, Center for the Origins of Life, Georgia Institute of Technology, Atlanta, GA, USA
| | - Caeden D Meade
- School of Chemistry and Biochemistry, Center for the Origins of Life, Georgia Institute of Technology, Atlanta, GA, USA
| | - Loren Dean Williams
- School of Chemistry and Biochemistry, Center for the Origins of Life, Georgia Institute of Technology, Atlanta, GA, USA
| | - Anton S Petrov
- School of Chemistry and Biochemistry, Center for the Origins of Life, Georgia Institute of Technology, Atlanta, GA, USA
| | - Patricia P Chan
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Todd M Lowe
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Robert D Finn
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - Anton I Petrov
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK.
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88
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Mechanistic insights into mitochondrial tRNA Ala 3'-end metabolism deficiency. J Biol Chem 2021; 297:100816. [PMID: 34023389 PMCID: PMC8212662 DOI: 10.1016/j.jbc.2021.100816] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/10/2021] [Accepted: 05/19/2021] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial tRNA 3’-end metabolism is critical for the formation of functional tRNAs. Deficient mitochondrial tRNA 3’-end metabolism is linked to an array of human diseases, including optic neuropathy, but their pathophysiology remains poorly understood. In this report, we investigated the molecular mechanism underlying the Leber’s hereditary optic neuropathy (LHON)-associated tRNAAla 5587A>G mutation, which changes a highly conserved adenosine at position 73 (A73) to guanine (G73) on the 3’-end of the tRNA acceptor stem. The m.5587A>G mutation was identified in three Han Chinese families with suggested maternal inheritance of LHON. We hypothesized that the m.5587A>G mutation altered tRNAAla 3’-end metabolism and mitochondrial function. In vitro processing experiments showed that the m.5587A>G mutation impaired the 3’-end processing of tRNAAla precursors by RNase Z and inhibited the addition of CCA by tRNA nucleotidyltransferase (TRNT1). Northern blot analysis revealed that the m.5587A>G mutation perturbed tRNAAla aminoacylation, as evidenced by decreased efficiency of aminoacylation and faster electrophoretic mobility of mutated tRNAAla in these cells. The impact of m.5587A>G mutation on tRNAAla function was further supported by increased melting temperature, conformational changes, and reduced levels of this tRNA. Failures in tRNAAla metabolism impaired mitochondrial translation, perturbed assembly and activity of oxidative phosphorylation complexes, diminished ATP production and membrane potential, and increased production of reactive oxygen species. These pleiotropic defects elevated apoptotic cell death and promoted mitophagy in cells carrying the m.5587A>G mutation, thereby contributing to visual impairment. Our findings may provide new insights into the pathophysiology of LHON arising from mitochondrial tRNA 3’-end metabolism deficiency.
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89
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Tharp JM, Vargas-Rodriguez O, Schepartz A, Söll D. Genetic Encoding of Three Distinct Noncanonical Amino Acids Using Reprogrammed Initiator and Nonsense Codons. ACS Chem Biol 2021; 16:766-774. [PMID: 33723984 DOI: 10.1021/acschembio.1c00120] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We recently described an orthogonal initiator tRNA (itRNATy2) that can initiate protein synthesis with noncanonical amino acids (ncAAs) in response to the UAG nonsense codon. Here, we report that a mutant of itRNATy2 (itRNATy2AUA) can efficiently initiate translation in response to the UAU tyrosine codon, giving rise to proteins with an ncAA at their N-terminus. We show that, in cells expressing itRNATy2AUA, UAU can function as a dual-use codon that selectively encodes ncAAs at the initiating position and predominantly tyrosine at elongating positions. Using itRNATy2AUA, in conjunction with its cognate tyrosyl-tRNA synthetase and two mutually orthogonal pyrrolysyl-tRNA synthetases, we demonstrate that UAU can be reassigned along with UAG or UAA to encode two distinct ncAAs in the same protein. Furthermore, by engineering the substrate specificity of one of the pyrrolysyl-tRNA synthetases, we developed a triply orthogonal system that enables simultaneous reassignment of UAU, UAG, and UAA to produce proteins containing three distinct ncAAs at precisely defined sites. To showcase the utility of this system, we produced proteins containing two or three ncAAs, with unique bioorthogonal functional groups, and demonstrate that these proteins can be separately modified with multiple fluorescent probes.
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90
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Rivas E. Evolutionary conservation of RNA sequence and structure. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1649. [PMID: 33754485 PMCID: PMC8250186 DOI: 10.1002/wrna.1649] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 12/22/2022]
Abstract
An RNA structure prediction from a single‐sequence RNA folding program is not evidence for an RNA whose structure is important for function. Random sequences have plausible and complex predicted structures not easily distinguishable from those of structural RNAs. How to tell when an RNA has a conserved structure is a question that requires looking at the evolutionary signature left by the conserved RNA. This question is important not just for long noncoding RNAs which usually lack an identified function, but also for RNA binding protein motifs which can be single stranded RNAs or structures. Here we review recent advances using sequence and structural analysis to determine when RNA structure is conserved or not. Although covariation measures assess structural RNA conservation, one must distinguish covariation due to RNA structure from covariation due to independent phylogenetic substitutions. We review a statistical test to measure false positives expected under the null hypothesis of phylogenetic covariation alone (specificity). We also review a complementary test that measures power, that is, expected covariation derived from sequence variation alone (sensitivity). Power in the absence of covariation signals the absence of a conserved RNA structure. We analyze artifacts that falsely identify conserved RNA structure such as the misuse of programs that do not assess significance, the use of inappropriate statistics confounded by signals other than covariation, or misalignments that induce spurious covariation. Among artifacts that obscure the signal of a conserved RNA structure, we discuss the inclusion of pseudogenes in alignments which increase power but destroy covariation. This article is categorized under:RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry RNA Evolution and Genomics > Computational Analyses of RNA RNA Evolution and Genomics > RNA and Ribonucleoprotein Evolution
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Affiliation(s)
- Elena Rivas
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
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91
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Ho JML, Miller CA, Parks SE, Mattia JR, Bennett M. A suppressor tRNA-mediated feedforward loop eliminates leaky gene expression in bacteria. Nucleic Acids Res 2021; 49:e25. [PMID: 33290521 PMCID: PMC7969014 DOI: 10.1093/nar/gkaa1179] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/11/2020] [Accepted: 11/19/2020] [Indexed: 11/13/2022] Open
Abstract
Ligand-inducible genetic systems are the mainstay of synthetic biology, allowing gene expression to be controlled by the presence of a small molecule. However, 'leaky' gene expression in the absence of inducer remains a persistent problem. We developed a leak dampener tool that drastically reduces the leak of inducible genetic systems while retaining signal in Escherichia coli. Our system relies on a coherent feedforward loop featuring a suppressor tRNA that enables conditional readthrough of silent non-sense mutations in a regulated gene, and this approach can be applied to any ligand-inducible transcription factor. We demonstrate proof-of-principle of our system with the lactate biosensor LldR and the arabinose biosensor AraC, which displayed a 70-fold and 630-fold change in output after induction of a fluorescence reporter, respectively, without any background subtraction. Application of the tool to an arabinose-inducible mutagenesis plasmid led to a 540-fold change in its output after induction, with leak decreasing to the level of background mutagenesis. This study provides a modular tool for reducing leak and improving the fold-induction within genetic circuits, demonstrated here using two types of biosensors relevant to cancer detection and genetic engineering.
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Affiliation(s)
- Joanne M L Ho
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA
| | - Corwin A Miller
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA
| | - Sydney E Parks
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA
| | - Jacob R Mattia
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA
| | - Matthew R Bennett
- Department of Biosciences, Rice University MS-140, 6100 Main St., Houston, TX 77005, USA
- Department of Bioengineering, Rice University MS-140, 6100 Main St. Houston, TX 77005, USA
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92
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Agmon I, Fayerverker I, Mor T. Coding triplets in the tRNA acceptor-TΨC arm and their role in present and past tRNA recognition. FEBS Lett 2021; 595:913-924. [PMID: 33460451 DOI: 10.1002/1873-3468.14044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/29/2020] [Accepted: 01/09/2021] [Indexed: 11/10/2022]
Abstract
The mechanism and evolution of the recognition scheme between key components of the translation system, that is, tRNAs, synthetases, and elongation factors, are fundamental issues in understanding the translation of genetic information into proteins. Statistical analysis of bacterial tRNA sequences reveals that for six amino acids, a string of 10 nucleotides preceding the tRNA 3' end carries cognate coding triplets to nearly full extent. The triplets conserved in positions 63-67 are implicated in the recognition by the elongation factor EF-Tu, and those conserved in positions 68-72, in the identification of cognate tRNAs, and their derived minihelices by class IIa synthetases. These coding triplets are suggested to have primordial origin, being engaged in aminoacylation of prebiotic tRNAs and in the establishment of the canonical codon set.
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Affiliation(s)
- Ilana Agmon
- Institute for Advanced Studies in Theoretical Chemistry, Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel.,Fritz Haber Research Center for Molecular Dynamics, Hebrew University Jerusalem, Israel
| | | | - Tal Mor
- Department of Computer Science, Technion, Haifa, Israel
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93
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Abstract
A nonsense suppressor tRNA (sup-tRNA) allows a natural or non-natural amino acid to be assigned to a nonsense codon in mRNA. Sup-tRNAs were utilized initially for studying tRNA functions but lately are used more for protein engineering and gene regulation. In the latter application, a sup-tRNA that is aminoacylated with a natural amino acid by the corresponding aminoacyl-tRNA synthetase is used to express a full-length natural protein from its mutated gene with a nonsense codon in the middle. This type of sup-tRNA has recently been artificially evolved to develop biosensors. In these biosensors, an analyte induces the processing of an engineered premature sup-tRNA into a mature sup-tRNA, which suppresses the corresponding nonsense codon incorporated into a gene, encoding an easily detectable reporter protein. This review introduces sup-tRNA-based biosensors that the author's group has developed by utilizing bacterial and eukaryotic cell-free translation systems.
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94
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Berg MD, Brandl CJ. Transfer RNAs: diversity in form and function. RNA Biol 2021; 18:316-339. [PMID: 32900285 PMCID: PMC7954030 DOI: 10.1080/15476286.2020.1809197] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/31/2020] [Accepted: 08/08/2020] [Indexed: 12/11/2022] Open
Abstract
As the adaptor that decodes mRNA sequence into protein, the basic aspects of tRNA structure and function are central to all studies of biology. Yet the complexities of their properties and cellular roles go beyond the view of tRNAs as static participants in protein synthesis. Detailed analyses through more than 60 years of study have revealed tRNAs to be a fascinatingly diverse group of molecules in form and function, impacting cell biology, physiology, disease and synthetic biology. This review analyzes tRNA structure, biosynthesis and function, and includes topics that demonstrate their diversity and growing importance.
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Affiliation(s)
- Matthew D. Berg
- Department of Biochemistry, The University of Western Ontario, London, Canada
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95
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Canu N, Tellier C, Babin M, Thai R, Ajel I, Seguin J, Cinquin O, Vinck R, Moutiez M, Belin P, Cintrat JC, Gondry M. Flexizyme-aminoacylated shortened tRNAs demonstrate that only the aminoacylated acceptor arms of the two tRNA substrates are required for cyclodipeptide synthase activity. Nucleic Acids Res 2021; 48:11615-11625. [PMID: 33095883 PMCID: PMC7672478 DOI: 10.1093/nar/gkaa903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/22/2020] [Accepted: 09/30/2020] [Indexed: 01/15/2023] Open
Abstract
Cyclodipeptide synthases (CDPSs) use two aminoacyl-tRNAs (AA-tRNAs) to catalyse cyclodipeptide formation in a ping-pong mechanism. Despite intense studies of these enzymes in past years, the tRNA regions of the two substrates required for CDPS activity are poorly documented, mainly because of two limitations. First, previously studied CDPSs use two identical AA-tRNAs to produce homocyclodipeptides, thus preventing the discriminative study of the binding of the two substrates. Second, the range of tRNA analogues that can be aminoacylated by aminoacyl-tRNA synthetases is limited. To overcome the limitations, we studied a new model CDPS that uses two different AA-tRNAs to produce an heterocyclodipeptide. We also developed a production pipeline for the production of purified shortened AA-tRNA analogues (AA-minitRNAs). This method combines the use of flexizymes to aminoacylate a diversity of minitRNAs and their subsequent purifications by anion-exchange chromatography. Finally, we were able to show that aminoacylated molecules mimicking the entire acceptor arms of tRNAs were as effective a substrate as entire AA-tRNAs, thereby demonstrating that the acceptor arms of the two substrates are the only parts of the tRNAs required for CDPS activity. The method developed in this study should greatly facilitate future investigations of the specificity of CDPSs and of other AA-tRNAs-utilizing enzymes.
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Affiliation(s)
- Nicolas Canu
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Carine Tellier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Morgan Babin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Robert Thai
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Inès Ajel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Jérôme Seguin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Olivier Cinquin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France.,Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SCBM, 91191 Gif-sur-Yvette, France
| | - Robin Vinck
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France.,Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SCBM, 91191 Gif-sur-Yvette, France
| | - Mireille Moutiez
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Pascal Belin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Jean-Christophe Cintrat
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SCBM, 91191 Gif-sur-Yvette, France
| | - Muriel Gondry
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
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96
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Phillips JB, Ardell DH. Structural and Genetic Determinants of Convergence in the Drosophila tRNA Structure-Function Map. J Mol Evol 2021; 89:103-116. [PMID: 33528599 PMCID: PMC7884595 DOI: 10.1007/s00239-021-09995-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 01/11/2021] [Indexed: 10/29/2022]
Abstract
The evolution of tRNA multigene families remains poorly understood, exhibiting unusual phenomena such as functional conversions of tRNA genes through anticodon shift substitutions. We improved FlyBase tRNA gene annotations from twelve Drosophila species, incorporating previously identified ortholog sets to compare substitution rates across tRNA bodies at single-site and base-pair resolution. All rapidly evolving sites fell within the same metal ion-binding pocket that lies at the interface of the two major stacked helical domains. We applied our tRNA Structure-Function Mapper (tSFM) method independently to each Drosophila species and one outgroup species Musca domestica and found that, although predicted tRNA structure-function maps are generally highly conserved in flies, one tRNA Class-Informative Feature (CIF) within the rapidly evolving ion-binding pocket-Cytosine 17 (C17), ancestrally informative for lysylation identity-independently gained asparaginylation identity and substituted in parallel across tRNAAsn paralogs at least once, possibly multiple times, during evolution of the genus. In D. melanogaster, most tRNALys and tRNAAsn genes are co-arrayed in one large heterologous gene cluster, suggesting that heterologous gene conversion as well as structural similarities of tRNA-binding interfaces in the closely related asparaginyl-tRNA synthetase (AsnRS) and lysyl-tRNA synthetase (LysRS) proteins may have played a role in these changes. A previously identified Asn-to-Lys anticodon shift substitution in D. ananassae may have arisen to compensate for the convergent and parallel gains of C17 in tRNAAsn paralogs in that lineage. Our results underscore the functional and evolutionary relevance of our tRNA structure-function map predictions and illuminate multiple genomic and structural factors contributing to rapid, parallel and compensatory evolution of tRNA multigene families.
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Affiliation(s)
- Julie Baker Phillips
- Quantitative and Systems Biology Program, University of California, Merced, CA, 95343, USA
- Department of Biology, Cumberland University, 1 Cumberland Square, Lebanon, TN, 37087, USA
| | - David H Ardell
- Quantitative and Systems Biology Program, University of California, Merced, CA, 95343, USA.
- Department of Molecular and Cell Biology, University of California, Merced, CA, 95343, USA.
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97
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Tang Z, Tang X, Xue L, Guan M. [A non-invasive method for detecting mitochondrial tRNA Thr15927G>A mutation]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2021; 41:151-156. [PMID: 33509769 DOI: 10.12122/j.issn.1673-4254.2021.01.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To explore the feasibility of detecting maternal hereditary mitochondrial tRNAThr15927G>A (m.15927G>A) mutation using buccal swabs. METHODS We performed sequence analysis of mitochondrial DNA in blood samples from 2070 cases of maternal hereditary mitochondrial disease in the First Affiliated Hospital of Wenzhou Medical University, and identified 3 patients with m.15927G>A mutation.Buccal swabs and blood samples were obtained from the 3 patients (mutation group) and 3 normal volunteers (control group).After extracting whole genomic DNA from all the samples, the DNA concentration and purity were analyzed.The PCR products were subjected to dot blot hybridization, Southern blot hybridization, and DNA sequencing analysis to verify the feasibility of detecting m.15927G>A mutation using buccal swabs. RESULTS There was no significant difference in DNA concentration extracted from buccal swabs and blood samples in either the mutation group or the control group (P > 0.05), but the purity of manually extracted oral mucosa DNA was significantly lower than that of whole blood and oral mucosa DNA extracted using commercial kits (P < 0.05).Dot blot hybridization and Southern blot hybridization both yielded positive results in the control group but negative results in the mutation group.DNA sequencing identified m.15927G>A mutation in all the samples from the mutation group. CONCLUSIONS Buccal swabs collection accurate is an accurate and sensitive method for the detection of m.15927G>A mutation.
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Affiliation(s)
- Zhining Tang
- School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325035, China
| | - Xiaowen Tang
- School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325035, China
| | - Ling Xue
- School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325035, China
| | - Minxin Guan
- School of Laboratory Medicine and Life Sciences, Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325035, China
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98
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Schwark DG, Schmitt MA, Fisk JD. Directed Evolution of the Methanosarcina barkeri Pyrrolysyl tRNA/aminoacyl tRNA Synthetase Pair for Rapid Evaluation of Sense Codon Reassignment Potential. Int J Mol Sci 2021; 22:E895. [PMID: 33477414 PMCID: PMC7830368 DOI: 10.3390/ijms22020895] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/10/2021] [Accepted: 01/12/2021] [Indexed: 12/20/2022] Open
Abstract
Genetic code expansion has largely focused on the reassignment of amber stop codons to insert single copies of non-canonical amino acids (ncAAs) into proteins. Increasing effort has been directed at employing the set of aminoacyl tRNA synthetase (aaRS) variants previously evolved for amber suppression to incorporate multiple copies of ncAAs in response to sense codons in Escherichia coli. Predicting which sense codons are most amenable to reassignment and which orthogonal translation machinery is best suited to each codon is challenging. This manuscript describes the directed evolution of a new, highly efficient variant of the Methanosarcina barkeri pyrrolysyl orthogonal tRNA/aaRS pair that activates and incorporates tyrosine. The evolved M. barkeri tRNA/aaRS pair reprograms the amber stop codon with 98.1 ± 3.6% efficiency in E. coli DH10B, rivaling the efficiency of the wild-type tyrosine-incorporating Methanocaldococcus jannaschii orthogonal pair. The new orthogonal pair is deployed for the rapid evaluation of sense codon reassignment potential using our previously developed fluorescence-based screen. Measurements of sense codon reassignment efficiencies with the evolved M. barkeri machinery are compared with related measurements employing the M. jannaschii orthogonal pair system. Importantly, we observe different patterns of sense codon reassignment efficiency for the M. jannaschii tyrosyl and M. barkeri pyrrolysyl systems, suggesting that particular codons will be better suited to reassignment by different orthogonal pairs. A broad evaluation of sense codon reassignment efficiencies to tyrosine with the M. barkeri system will highlight the most promising positions at which the M. barkeri orthogonal pair may infiltrate the E. coli genetic code.
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Affiliation(s)
| | | | - John D. Fisk
- Department of Chemistry, University of Colorado Denver, Campus Box 194, P.O. Box 173364, Denver, CO 80217-3364, USA; (D.G.S.); (M.A.S.)
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Singh T, Yadav SK, Vainstein A, Kumar V. Genome recoding strategies to improve cellular properties: mechanisms and advances. ABIOTECH 2021; 2:79-95. [PMID: 34377578 PMCID: PMC7675020 DOI: 10.1007/s42994-020-00030-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 10/07/2020] [Indexed: 11/10/2022]
Abstract
The genetic code, once believed to be universal and immutable, is now known to contain many variations and is not quite universal. The basis for genome recoding strategy is genetic code variation that can be harnessed to improve cellular properties. Thus, genome recoding is a promising strategy for the enhancement of genome flexibility, allowing for novel functions that are not commonly documented in the organism in its natural environment. Here, the basic concept of genetic code and associated mechanisms for the generation of genetic codon variants, including biased codon usage, codon reassignment, and ambiguous decoding, are extensively discussed. Knowledge of the concept of natural genetic code expansion is also detailed. The generation of recoded organisms and associated mechanisms with basic targeting components, including aminoacyl-tRNA synthetase-tRNA pairs, elongation factor EF-Tu and ribosomes, are highlighted for a comprehensive understanding of this concept. The research associated with the generation of diverse recoded organisms is also discussed. The success of genome recoding in diverse multicellular organisms offers a platform for expanding protein chemistry at the biochemical level with non-canonical amino acids, genetically isolating the synthetic organisms from the natural ones, and fighting viruses, including SARS-CoV2, through the creation of attenuated viruses. In conclusion, genome recoding can offer diverse applications for improving cellular properties in the genome-recoded organisms.
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Affiliation(s)
- Tanya Singh
- Department of Botany, School of Basic Sciences, Central University of Punjab, Bathinda, 151001 India
| | | | - Alexander Vainstein
- Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Vinay Kumar
- Department of Botany, School of Basic Sciences, Central University of Punjab, Bathinda, 151001 India
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Abstract
The encoded biosynthesis of proteins provides the ultimate paradigm for high-fidelity synthesis of long polymers of defined sequence and composition, but it is limited to polymerizing the canonical amino acids. Recent advances have built on genetic code expansion - which commonly permits the cellular incorporation of one type of non-canonical amino acid into a protein - to enable the encoded incorporation of several distinct non-canonical amino acids. Developments include strategies to read quadruplet codons, use non-natural DNA base pairs, synthesize completely recoded genomes and create orthogonal translational components with reprogrammed specificities. These advances may enable the genetically encoded synthesis of non-canonical biopolymers and provide a platform for transforming the discovery and evolution of new materials and therapeutics.
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Affiliation(s)
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
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