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Chen XR, Cui YZ, Li BZ, Yuan YJ. Genome engineering on size reduction and complexity simplification: A review. J Adv Res 2024; 60:159-171. [PMID: 37442424 PMCID: PMC11156615 DOI: 10.1016/j.jare.2023.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/25/2023] [Accepted: 07/10/2023] [Indexed: 07/15/2023] Open
Abstract
BACKGROUND Genome simplification is an important topic in the field of life sciences that has attracted attention from its conception to the present day. It can help uncover the essential components of the genome and, in turn, shed light on the underlying operating principles of complex biological systems. This has made it a central focus of both basic and applied research in the life sciences. With the recent advancements in related technologies and our increasing knowledge of the genome, now is an opportune time to delve into this topic. AIM OF REVIEW Our review investigates the progress of genome simplification from two perspectives: genome size reduction and complexity simplification. In addition, we provide insights into the future development trends of genome simplification. KEY SCIENTIFIC CONCEPTS OF REVIEW Reducing genome size requires eliminating non-essential elements as much as possible. This process has been facilitated by advances in genome manipulation and synthesis techniques. However, we still need a better and clearer understanding of living systems to reduce genome complexity. As there is a lack of quantitative and clearly defined standards for this task, we have opted to approach the topic from various perspectives and present our findings accordingly.
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Affiliation(s)
- Xiang-Rong Chen
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China; Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin, China
| | - You-Zhi Cui
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China; Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin, China
| | - Bing-Zhi Li
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China; Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin, China.
| | - Ying-Jin Yuan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China; Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin, China
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2
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Schindler D, Walker RSK, Jiang S, Brooks AN, Wang Y, Müller CA, Cockram C, Luo Y, García A, Schraivogel D, Mozziconacci J, Pena N, Assari M, Sánchez Olmos MDC, Zhao Y, Ballerini A, Blount BA, Cai J, Ogunlana L, Liu W, Jönsson K, Abramczyk D, Garcia-Ruiz E, Turowski TW, Swidah R, Ellis T, Pan T, Antequera F, Shen Y, Nieduszynski CA, Koszul R, Dai J, Steinmetz LM, Boeke JD, Cai Y. Design, construction, and functional characterization of a tRNA neochromosome in yeast. Cell 2023; 186:5237-5253.e22. [PMID: 37944512 DOI: 10.1016/j.cell.2023.10.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 09/22/2023] [Accepted: 10/12/2023] [Indexed: 11/12/2023]
Abstract
Here, we report the design, construction, and characterization of a tRNA neochromosome, a designer chromosome that functions as an additional, de novo counterpart to the native complement of Saccharomyces cerevisiae. Intending to address one of the central design principles of the Sc2.0 project, the ∼190-kb tRNA neochromosome houses all 275 relocated nuclear tRNA genes. To maximize stability, the design incorporates orthogonal genetic elements from non-S. cerevisiae yeast species. Furthermore, the presence of 283 rox recombination sites enables an orthogonal tRNA SCRaMbLE system. Following construction in yeast, we obtained evidence of a potent selective force, manifesting as a spontaneous doubling in cell ploidy. Furthermore, tRNA sequencing, transcriptomics, proteomics, nucleosome mapping, replication profiling, FISH, and Hi-C were undertaken to investigate questions of tRNA neochromosome behavior and function. Its construction demonstrates the remarkable tractability of the yeast model and opens up opportunities to directly test hypotheses surrounding these essential non-coding RNAs.
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Affiliation(s)
- Daniel Schindler
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK; Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany; Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, 35032 Marburg, Germany
| | - Roy S K Walker
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Edinburgh EH9 3BF, Scotland; School of Natural Sciences and ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW 2109, Australia
| | - Shuangying Jiang
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics and Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Aaron N Brooks
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany
| | - Yun Wang
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China; Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen 518120, China
| | - Carolin A Müller
- Earlham Institute, Norwich Research Park, Norwich NR4 7UZ, UK; School of Biological Sciences, University of East Anglia, Norwich NR4 7TU, UK
| | - Charlotte Cockram
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, 75015 Paris, France
| | - Yisha Luo
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK
| | - Alicia García
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Universidad de Salamanca, Salamanca, Spain
| | - Daniel Schraivogel
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany
| | - Julien Mozziconacci
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, 75015 Paris, France
| | - Noah Pena
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Mahdi Assari
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | | | - Yu Zhao
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
| | - Alba Ballerini
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK
| | - Benjamin A Blount
- Imperial College Centre for Synthetic Biology, Imperial College London, London, UK; Department of Bioengineering, Imperial College London, London, UK
| | - Jitong Cai
- Department of Biomedical Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Lois Ogunlana
- School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland
| | - Wei Liu
- School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland
| | - Katarina Jönsson
- School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland
| | - Dariusz Abramczyk
- School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland
| | - Eva Garcia-Ruiz
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK
| | - Tomasz W Turowski
- Institute of Biochemistry and Biophysics PAS, Pawińskiego 5a, 02-106 Warszawa, Poland
| | - Reem Swidah
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK
| | - Tom Ellis
- Imperial College Centre for Synthetic Biology, Imperial College London, London, UK; Department of Bioengineering, Imperial College London, London, UK
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Francisco Antequera
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Universidad de Salamanca, Salamanca, Spain
| | - Yue Shen
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK; BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China; Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen 518120, China
| | - Conrad A Nieduszynski
- Earlham Institute, Norwich Research Park, Norwich NR4 7UZ, UK; School of Biological Sciences, University of East Anglia, Norwich NR4 7TU, UK
| | - Romain Koszul
- Institut Pasteur, CNRS UMR 3525, Université Paris Cité, Unité Régulation Spatiale des Génomes, 75015 Paris, France
| | - Junbiao Dai
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics and Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany; Department of Genetics and Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA; Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY 11201, USA
| | - Yizhi Cai
- Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, UK.
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3
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A dynamical stochastic model of yeast translation across the cell cycle. Heliyon 2023; 9:e13101. [PMID: 36793957 PMCID: PMC9922973 DOI: 10.1016/j.heliyon.2023.e13101] [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: 03/18/2022] [Revised: 01/04/2023] [Accepted: 01/16/2023] [Indexed: 01/27/2023] Open
Abstract
Translation is a central step in gene expression, however its quantitative and time-resolved regulation is poorly understood. We developed a discrete, stochastic model for protein translation in S. cerevisiae in a whole-transcriptome, single-cell context. A "base case" scenario representing an average cell highlights translation initiation rates as the main co-translational regulatory parameters. Codon usage bias emerges as a secondary regulatory mechanism through ribosome stalling. Demand for anticodons with low abundancy is shown to cause above-average ribosome dwelling times. Codon usage bias correlates strongly both with protein synthesis rates and elongation rates. Applying the model to a time-resolved transcriptome estimated by combining data from FISH and RNA-Seq experiments, it could be shown that increased total transcript abundance during the cell cycle decreases translation efficiency at single transcript level. Translation efficiency grouped by gene function shows highest values for ribosomal and glycolytic genes. Ribosomal proteins peak in S phase while glycolytic proteins rank highest in later cell cycle phases.
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4
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Identification and analysis of putative tRNA genes in baculovirus genomes. Virus Res 2022; 322:198949. [PMID: 36181979 DOI: 10.1016/j.virusres.2022.198949] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 12/24/2022]
Abstract
Transfer RNAs (tRNAs) genes are both coded for and arranged along some viral genomes representing the entire virosphere and seem to play different biological functions during infection, other than transferring the correct amino acid to a growing peptide chain. Baculovirus genome description and annotation has focused mostly on protein-coding genes, microRNA, and homologous regions. Here we carried out a large-scale in silico search for putative tRNA genes in baculovirus genomes. Ninety-six of 257 baculovirus genomes analyzed was found to contain at least one putative tRNA gene. We found great diversity in primary and secondary structure, in location within the genome, in intron presence and size, and in anti-codon identity. In some cases, genes of tRNA-containing genomes were found to have a bias for the codons specified by the tRNAs present in such genomes. Moreover, analysis revealed that most of the putative tRNA genes possessed conserved motifs for tRNA type 2 promoters, including the A-box and B-box motifs with few mismatches from the eukaryotic canonical motifs. From publicly available small RNA deep sequencing datasets of baculovirus-infected insect cells, we found evidence that a putative Autographa californica multiple nucleopolyhedrovirus Gln-tRNA gene was transcribed and modified with the addition of the non-templated 3'-CCA tail found at the end of all tRNAs. Further research is needed to determine the expression and functionality of these viral tRNAs.
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5
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Tavares JF, Davis NK, Poim A, Reis A, Kellner S, Sousa I, Soares AR, Moura GMR, Dedon PC, Santos M. tRNA-modifying enzyme mutations induce codon-specific mistranslation and protein aggregation in yeast. RNA Biol 2021; 18:563-575. [PMID: 32893724 PMCID: PMC7971265 DOI: 10.1080/15476286.2020.1819671] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 01/28/2023] Open
Abstract
Protein synthesis rate and accuracy are tightly controlled by the cell and are essential for proteome homoeostasis (proteostasis); however, the full picture of how mRNA translational factors maintain protein synthesis accuracy and co-translational protein folding are far from being fully understood. To address this question, we evaluated the role of 70 yeast tRNA-modifying enzyme genes on protein aggregation and used mass spectrometry to identify the aggregated proteins. We show that modification of uridine at anticodon position 34 (U34) by the tRNA-modifying enzymes Elp1, Elp3, Sml3 and Trm9 is critical for proteostasis, the mitochondrial tRNA-modifying enzyme Slm3 plays a fundamental role in general proteostasis and that stress response proteins whose genes are enriched in codons decoded by tRNAs lacking mcm5U34, mcm5s2U34, ncm5U34, ncm5Um34, modifications are overrepresented in protein aggregates of the ELP1, SLM3 and TRM9 KO strains. Increased rates of amino acid misincorporation were also detected in these strains at protein sites that specifically mapped to the codons sites that are decoded by the hypomodified tRNAs, demonstrating that U34 tRNA modifications safeguard the proteome from translational errors, protein misfolding and proteotoxic stress.
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Affiliation(s)
- Joana F Tavares
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
| | - Nick K. Davis
- Department of Biological Engineering, Massachusetts Institute of Technology – MIT, Cambridge, US
| | - Ana Poim
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
| | - Andreia Reis
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
| | - Stefanie Kellner
- Department of Biological Engineering, Massachusetts Institute of Technology – MIT, Cambridge, US
| | - Inês Sousa
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ana R. Soares
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
| | - Gabriela M R Moura
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
| | - Peter C Dedon
- Department of Biological Engineering, Massachusetts Institute of Technology – MIT, Cambridge, US
- Singapore-MIT Alliance for Research and Technology, Campus for Research Excellence and Technical Enterprise – CREATE, Singapore
| | - Manuel Santos
- Department of Medical Sciences, Institute of Biomedicine – iBiMED, University of Aveiro, Aveiro, Portugal
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6
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Guimarães AR, Correia I, Sousa I, Oliveira C, Moura G, Bezerra AR, Santos MAS. tRNAs as a Driving Force of Genome Evolution in Yeast. Front Microbiol 2021; 12:634004. [PMID: 33776966 PMCID: PMC7990762 DOI: 10.3389/fmicb.2021.634004] [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: 11/26/2020] [Accepted: 02/01/2021] [Indexed: 11/29/2022] Open
Abstract
Transfer RNAs (tRNAs) are widely known for their roles in the decoding of the linear mRNA information into amino acid sequences of proteins. They are also multifunctional platforms in the translation process and have other roles beyond translation, including sensing amino acid abundance, interacting with the general stress response machinery, and modulating cellular adaptation, survival, and death. In this mini-review, we focus on the emerging role of tRNA genes in the organization and modification of the genomic architecture of yeast and the role of tRNA misexpression and decoding infidelity in genome stability, evolution, and adaption. We discuss published work showing how quickly tRNA genes can mutate to meet novel translational demands, how tRNAs speed up genome evolution, and how tRNA genes can be sites of genomic instability. We highlight recent works showing that loss of tRNA decoding fidelity and small alterations in tRNA expression have unexpected and profound impacts on genome stability. By dissecting these recent evidence, we hope to lay the groundwork that prompts future investigations on the mechanistic interplay between tRNAs and genome modification that likely triggers genome evolution.
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Affiliation(s)
- Ana Rita Guimarães
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Inês Correia
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Inês Sousa
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Carla Oliveira
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Gabriela Moura
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ana Rita Bezerra
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Manuel A S Santos
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
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7
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Kielkopf CL, Bauer W, Urbatsch IL. Expression of Cloned Genes in Pichia pastoris Using the Methanol-Inducible Promoter AOX1. Cold Spring Harb Protoc 2021; 2021:2021/1/pdb.prot102160. [PMID: 33397779 DOI: 10.1101/pdb.prot102160] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pichia pastoris is a methylotrophic yeast capable of metabolizing methanol as its sole carbon source. Growth in methanol-containing medium results in dramatic induction of genes in the alcohol oxidation pathway including alcohol oxidase (AOX), formaldehyde dehydrogenase (FLD), and dihydroxyacetone synthase (DHAS). These proteins may comprise up to 30% of the biomass. Investigators have exploited these methanol-dependent genes to generate tightly regulated expression vectors. Most Pichia vectors use the strong and tightly regulated AOX1 promoter to drive heterologous protein expression. Obtaining integrated Pichia transformants requires more DNA than transformations into Saccharomyces cerevisiae, where the gene is expressed from episomal plasmids; however, transformants are extremely stable and can be stored for many years.
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8
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Shukla A, Bhalla P, Potdar PK, Jampala P, Bhargava P. Transcription-dependent enrichment of the yeast FACT complex influences nucleosome dynamics on the RNA polymerase III-transcribed genes. RNA (NEW YORK, N.Y.) 2020; 27:rna.077974.120. [PMID: 33277439 PMCID: PMC7901838 DOI: 10.1261/rna.077974.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 11/30/2020] [Indexed: 05/04/2023]
Abstract
The FACT (FAcilitates Chromatin Transactions) complex influences transcription initiation and enables passage of RNA polymerase (pol) II through gene body nucleosomes during elongation. In the budding yeast, ~280 non-coding RNA genes highly transcribed in vivo by pol III are found in the nucleosome-free regions bordered by positioned nucleosomes. The downstream nucleosome dynamics was found to regulate transcription via controlling the gene terminator accessibility and hence, terminator-dependent pol III recycling. As opposed to the enrichment at the 5'-ends of pol II-transcribed genes, our genome-wide mapping found transcription-dependent enrichment of the FACT subunit Spt16 near the 3'-end of all pol III-transcribed genes. Spt16 physically associates with the pol III transcription complex and shows gene-specific occupancy levels on the individual genes. On the non-tRNA pol III-transcribed genes, Spt16 facilitates transcription by reducing the nucleosome occupany on the gene body. On the tRNA genes, it maintains the position of the nucleosome at the 3' gene-end and affects transcription in gene-specific manner. Under nutritional stress, Spt16 enrichment is abolished in the gene downstream region of all pol III-transcribed genes and reciprocally changed on the induced or repressed pol II-transcribed ESR genes. Under the heat and replicative stress, its occupancy on the pol III-transcribed genes increases significantly. Our results show that Spt16 elicits a differential, gene-specific and stress-responsive dynamics, which provides a novel stress-sensor mechanism of regulating transcription against external stress. By primarily influencing the nucleosomal organization, FACT links the downstream nucleosome dynamics to transcription and environmental stress on the pol III-transcribed genes.
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9
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Ahmed N, Friedrich UA, Sormanni P, Ciryam P, Altman NS, Bukau B, Kramer G, O'Brien EP. Pairs of amino acids at the P- and A-sites of the ribosome predictably and causally modulate translation-elongation rates. J Mol Biol 2020; 432:166696. [PMID: 33152326 DOI: 10.1016/j.jmb.2020.10.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 08/30/2020] [Accepted: 10/19/2020] [Indexed: 12/31/2022]
Abstract
Variation in translation-elongation kinetics along a transcript's coding sequence plays an important role in the maintenance of cellular protein homeostasis by regulating co-translational protein folding, localization, and maturation. Translation-elongation speed is influenced by molecular factors within mRNA and protein sequences. For example, the presence of proline in the ribosome's P- or A-site slows down translation, but the effect of other pairs of amino acids, in the context of all 400 possible pairs, has not been characterized. Here, we study Saccharomyces cerevisiae using a combination of bioinformatics, mutational experiments, and evolutionary analyses, and show that many different pairs of amino acids and their associated tRNA molecules predictably and causally encode translation rate information when these pairs are present in the A- and P-sites of the ribosome independent of other factors known to influence translation speed including mRNA structure, wobble base pairing, tripeptide motifs, positively charged upstream nascent chain residues, and cognate tRNA concentration. The fast-translating pairs of amino acids that we identify are enriched four-fold relative to the slow-translating pairs across Saccharomyces cerevisiae's proteome, while the slow-translating pairs are enriched downstream of domain boundaries. Thus, the chemical identity of amino acid pairs contributes to variability in translation rates, elongation kinetics are causally encoded in the primary structure of proteins, and signatures of evolutionary selection indicate their potential role in co-translational processes.
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Affiliation(s)
- Nabeel Ahmed
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Ulrike A Friedrich
- Center for Molecular Biology of the Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Pietro Sormanni
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - Prajwal Ciryam
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - Naomi S Altman
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA; Department of Statistics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Bernd Bukau
- Center for Molecular Biology of the Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Günter Kramer
- Center for Molecular Biology of the Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Edward P O'Brien
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA; Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA; Institute for Computational and Data Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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10
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Hayashi S, Mori S, Suzuki T, Suzuki T, Yoshihisa T. Impact of intron removal from tRNA genes on Saccharomyces cerevisiae. Nucleic Acids Res 2019; 47:5936-5949. [PMID: 30997502 PMCID: PMC6582322 DOI: 10.1093/nar/gkz270] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/28/2019] [Accepted: 04/04/2019] [Indexed: 12/31/2022] Open
Abstract
In eukaryotes and archaea, tRNA genes frequently contain introns, which are removed during maturation. However, biological roles of tRNA introns remain elusive. Here, we constructed a complete set of Saccharomyces cerevisiae strains in which the introns were removed from all the synonymous genes encoding 10 different tRNA species. All the intronless strains were viable, but the tRNAPheGAA and tRNATyrGUA intronless strains displayed slow growth, cold sensitivity and defective growth under respiratory conditions, indicating physiological importance of certain tRNA introns. Northern analyses revealed that removal of the introns from genes encoding three tRNAs reduced the amounts of the corresponding mature tRNAs, while it did not affect aminoacylation. Unexpectedly, the tRNALeuCAA intronless strain showed reduced 5.8S rRNA levels and abnormal nucleolar morphology. Because pseudouridine (Ψ) occurs at position 34 of the tRNAIleUAU anticodon in an intron-dependent manner, tRNAIleUAU in the intronless strain lost Ψ34. However, in a portion of tRNAIleUAU population, position 34 was converted into 5-carbamoylmethyluridine (ncm5U), which could reduce decoding fidelity. In summary, our results demonstrate that, while introns are dispensable for cell viability, some introns have diverse roles, such as ensuring proper growth under various conditions and controlling the appropriate anticodon modifications for accurate pairing with the codon.
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Affiliation(s)
- Sachiko Hayashi
- Graduate School of Life Science, University of Hyogo, Ako-gun 678-1297, Japan
| | - Shunsuke Mori
- Graduate School of Materials Science, Nagoya University, Nagoya 464-8602, Japan
| | - Takeo Suzuki
- Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Tohru Yoshihisa
- Graduate School of Life Science, University of Hyogo, Ako-gun 678-1297, Japan
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11
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Hummel G, Warren J, Drouard L. The multi-faceted regulation of nuclear tRNA gene transcription. IUBMB Life 2019; 71:1099-1108. [PMID: 31241827 DOI: 10.1002/iub.2097] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/16/2019] [Indexed: 12/31/2022]
Abstract
Transfer RNAs are among the most ancient molecules of life on earth. Beyond their crucial role in protein synthesis as carriers of amino acids, they are also important players in a plethora of other biological processes. Many debates in term of biogenesis, regulation and function persist around these fascinating non-coding RNAs. Our review focuses on the first step of their biogenesis in eukaryotes, i.e. their transcription from nuclear genes. Numerous and complementary ways have emerged during evolution to regulate transfer RNA gene transcription. Here, we will summarize the different actors implicated in this process: cis-elements, trans-factors, genomic contexts, epigenetic environments and finally three-dimensional organization of nuclear genomes. © 2019 IUBMB Life, 2019 © 2019 IUBMB Life, 71(8):1099-1108, 2019.
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Affiliation(s)
- Guillaume Hummel
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - Jessica Warren
- Department of biology, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Laurence Drouard
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
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12
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Abstract
A central result of stochastic thermodynamics is that irreversible state transitions of Markovian systems entail a cost in terms of an infinite entropy production. A corollary of this is that strictly deterministic computation is not possible. Using a thermodynamically consistent model, we show that quasideterministic computation can be achieved at finite, and indeed modest cost with accuracies that are indistinguishable from deterministic behavior for all practical purposes. Concretely, we consider the entropy production of stochastic (Markovian) systems that behave like and and a not gates. Combinations of these gates can implement any logical function. We require that these gates return the correct result with a probability that is very close to 1, and additionally, that they do so within finite time. The central component of the model is a machine that can read and write binary tapes. We find that the error probability of the computation of these gates falls with the power of the system size, whereas the cost only increases linearly with the system size.
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Affiliation(s)
- Dominique Chu
- School of Computing, University of Kent, CT2 7NF, Canterbury, United Kingdom
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13
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Devi M, Chingbiaknem E, Lyngdoh RHD. A molecular mechanics study on GA codon box translation. J Theor Biol 2018; 441:28-43. [PMID: 29305181 DOI: 10.1016/j.jtbi.2018.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 01/01/2018] [Accepted: 01/02/2018] [Indexed: 11/28/2022]
Abstract
The GA codon box incorporates the two-fold degeneracy of aspartic acid and of glutamic acid. Using the molecular mechanics approach of the AMBER suite, the four codons of the GA box are paired via H-bonding with two aspartic acid anticodons and two glutamic acid anticodons to yield 8 cognate and 11 non-cognate codon-anticodon duplexes. In addition four select non-cognate duplexes between the GA box codons and three alanine anticodons are also studied. These 23 duplexes display a variety of base-pairing possibilities at the wobble position. Cognate duplexes are differentiated from non-cognate duplexes on the grounds of structure and stability (chiefly the former). The results are in line with Crick's wobble hypothesis, and corroborate the observed reading properties of the aspartic acid anticodons GUC and QUC and of the glutamic acid anticodons CUC and SmnUC.
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Affiliation(s)
- Martina Devi
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
| | - Esther Chingbiaknem
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
| | - R H Duncan Lyngdoh
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India.
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14
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Leśniewska E, Boguta M. Novel layers of RNA polymerase III control affecting tRNA gene transcription in eukaryotes. Open Biol 2017; 7:rsob.170001. [PMID: 28228471 PMCID: PMC5356446 DOI: 10.1098/rsob.170001] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 01/31/2017] [Indexed: 12/20/2022] Open
Abstract
RNA polymerase III (Pol III) transcribes a limited set of short genes in eukaryotes producing abundant small RNAs, mostly tRNA. The originally defined yeast Pol III transcriptome appears to be expanding owing to the application of new methods. Also, several factors required for assembly and nuclear import of Pol III complex have been identified recently. Models of Pol III based on cryo-electron microscopy reconstructions of distinct Pol III conformations reveal unique features distinguishing Pol III from other polymerases. Novel concepts concerning Pol III functioning involve recruitment of general Pol III-specific transcription factors and distinctive mechanisms of transcription initiation, elongation and termination. Despite the short length of Pol III transcription units, mapping of transcriptionally active Pol III with nucleotide resolution has revealed strikingly uneven polymerase distribution along all genes. This may be related, at least in part, to the transcription factors bound at the internal promoter regions. Pol III uses also a specific negative regulator, Maf1, which binds to polymerase under stress conditions; however, a subset of Pol III genes is not controlled by Maf1. Among other RNA polymerases, Pol III machinery represents unique features related to a short transcript length and high transcription efficiency.
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Affiliation(s)
- Ewa Leśniewska
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Magdalena Boguta
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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15
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Shukla A, Bhargava P. Regulation of tRNA gene transcription by the chromatin structure and nucleosome dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1861:295-309. [PMID: 29313808 DOI: 10.1016/j.bbagrm.2017.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 01/19/2023]
Abstract
The short, non-coding genes transcribed by the RNA polymerase (pol) III, necessary for survival of a cell, need to be repressed under the stress conditions in vivo. The pol III-transcribed genes have adopted several novel chromatin-based regulatory mechanisms to their advantage. In the budding yeast, the sub-nucleosomal size tRNA genes are found in the nucleosome-free regions, flanked by positioned nucleosomes at both the ends. With their chromosomes-wide distribution, all tRNA genes have a different chromatin context. A single nucleosome dynamics controls the accessibility of the genes for transcription. This dynamics operates under the influence of several chromatin modifiers in a gene-specific manner, giving the scope for differential regulation of even the isogenes within a tRNA gene family. The chromatin structure around the pol III-transcribed genes provides a context conducive for steady-state transcription as well as gene-specific transcriptional regulation upon signaling from the environmental cues. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Affiliation(s)
- Ashutosh Shukla
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India
| | - Purnima Bhargava
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India.
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16
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Johansson MJO, Xu F, Byström AS. Elongator-a tRNA modifying complex that promotes efficient translational decoding. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1861:401-408. [PMID: 29170010 DOI: 10.1016/j.bbagrm.2017.11.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/19/2017] [Indexed: 12/22/2022]
Abstract
Naturally occurring modifications of the nucleosides in the anticodon region of tRNAs influence their translational decoding properties. Uridines present at the wobble position in eukaryotic cytoplasmic tRNAs often contain a 5-carbamoylmethyl (ncm(5)) or 5-methoxycarbonylmethyl (mcm(5)) side-chain and sometimes also a 2-thio or 2'-O-methyl group. The first step in the formation of the ncm(5) and mcm(5) side-chains requires the conserved six-subunit Elongator complex. Although Elongator has been implicated in several different cellular processes, accumulating evidence suggests that its primary, and possibly only, cellular function is to promote modification of tRNAs. In this review, we discuss the biosynthesis and function of modified wobble uridines in eukaryotic cytoplasmic tRNAs, focusing on the in vivo role of Elongator-dependent modifications in Saccharomyces cerevisiae. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Affiliation(s)
| | - Fu Xu
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - Anders S Byström
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden.
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17
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Hoffman KS, Berg MD, Shilton BH, Brandl CJ, O'Donoghue P. Genetic selection for mistranslation rescues a defective co-chaperone in yeast. Nucleic Acids Res 2017; 45:3407-3421. [PMID: 27899648 PMCID: PMC5389508 DOI: 10.1093/nar/gkw1021] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/18/2016] [Indexed: 12/22/2022] Open
Abstract
Despite the general requirement for translation fidelity, mistranslation can be an adaptive response. We selected spontaneous second site mutations that suppress the stress sensitivity caused by a Saccharomyces cerevisiae tti2 allele with a Leu to Pro mutation at residue 187, identifying a single nucleotide mutation at the same position (C70U) in four tRNAProUGG genes. Linkage analysis and suppression by SUF9G3:U70 expressed from a centromeric plasmid confirmed the causative nature of the suppressor mutation. Since the mutation incorporates the G3:U70 identity element for alanyl-tRNA synthetase into tRNAPro, we hypothesized that suppression results from mistranslation of Pro187 in Tti2L187P as Ala. A strain expressing Tti2L187A was not stress sensitive. In vitro, tRNAProUGG (C70U) was mis-aminoacylated with alanine by alanyl–tRNA synthetase, but was not a substrate for prolyl–tRNA synthetase. Mass spectrometry from protein expressed in vivo and a novel GFP reporter for mistranslation confirmed substitution of alanine for proline at a rate of ∼6%. Mistranslating cells expressing SUF9G3:U70 induce a partial heat shock response but grow nearly identically to wild-type. Introducing the same G3:U70 mutation in SUF2 (tRNAProAGG) suppressed a second tti2 allele (tti2L50P). We have thus identified a strategy that allows mistranslation to suppress deleterious missense Pro mutations in Tti2.
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Affiliation(s)
- Kyle S Hoffman
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Matthew D Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Brian H Shilton
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Patrick O'Donoghue
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.,Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
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18
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Devi M, Lyngdoh RD. Favored and less favored codon–anticodon duplexes arising from the GC codon family box encoding for alanine: some computational perspectives. J Biomol Struct Dyn 2017; 36:1029-1049. [DOI: 10.1080/07391102.2017.1308886] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Martina Devi
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
| | - R.H. Duncan Lyngdoh
- Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
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19
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Cakiroglu SA, Zaugg JB, Luscombe NM. Backmasking in the yeast genome: encoding overlapping information for protein-coding and RNA degradation. Nucleic Acids Res 2016; 44:8065-72. [PMID: 27492286 PMCID: PMC5041482 DOI: 10.1093/nar/gkw683] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 07/20/2016] [Accepted: 07/24/2016] [Indexed: 01/04/2023] Open
Abstract
Backmasking is a recording technique used to hide a sound or message in a music track in reverse, meaning that it is only audible when the record is played backwards. Analogously, the compact yeast genome encodes for diverse sources of information such as overlapping coding and non-coding transcripts, and protein-binding sites on the two complementary DNA strands. Examples are the consensus binding site sequences of the RNA-binding proteins Nrd1 and Nab3 that target non-coding transcripts for degradation. Here, by examining the overlap of stable (SUTs, stable unannotated transcripts) and unstable (CUTs, cryptic unstable transcripts) transcripts with protein-coding genes, we show that the predicted Nrd1 and Nab3-binding site sequences occur at differing frequencies. They are always depleted in the sense direction of protein-coding genes, thus avoiding degradation of the transcript. However in the antisense direction, predicted binding sites occur at high frequencies in genes with overlapping unstable ncRNAs (CUTs), so limiting the availability of non-functional transcripts. In contrast they are depleted in genes with overlapping stable ncRNAs (SUTs), presumably to avoid degrading the non-coding transcript. The protein-coding genes maintain similar amino-acid contents, but they display distinct codon usages so that Nrd1 and Nab3-binding sites can arise at differing frequencies in antisense depending on the overlapping transcript type. Our study demonstrates how yeast has evolved to encode multiple layers of information-protein-coding genes in one strand and the relative chance of degrading antisense RNA in the other strand-in the same regions of a compact genome.
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Affiliation(s)
- S Aylin Cakiroglu
- The Francis Crick Institute, 44 Lincoln's Inn Fields Laboratory, London WC2A 3LY, UK
| | - Judith B Zaugg
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nicholas M Luscombe
- The Francis Crick Institute, 44 Lincoln's Inn Fields Laboratory, London WC2A 3LY, UK UCL Genetics Institute, University College London, London WC1E 6BT, UK Okinawa Institute of Science & Technology Graduate University, Okinawa 904-0495, Japan
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20
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Foretek D, Nuc P, Żywicki M, Karlowski WM, Kudla G, Boguta M. Maf1-mediated regulation of yeast RNA polymerase III is correlated with CCA addition at the 3' end of tRNA precursors. Gene 2016; 612:12-18. [PMID: 27575455 PMCID: PMC5390780 DOI: 10.1016/j.gene.2016.08.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 08/18/2016] [Accepted: 08/20/2016] [Indexed: 11/30/2022]
Abstract
In eukaryotic cells tRNA synthesis is negatively regulated by the protein Maf1, conserved from yeast to humans. Maf1 from yeast Saccharomyces cerevisiae mediates repression of trna transcription when cells are transferred from medium with glucose to medium with glycerol, a non-fermentable carbon source. The strain with deleted gene encoding Maf1 (maf1Δ) is viable but accumulates tRNA precursors. In this study tRNA precursors were analysed by RNA-Seq and Northern hybridization in wild type strain and maf1Δ mutant grown in glucose medium or upon shift to repressive conditions. A negative effect of maf1Δ mutant on the addition of the auxiliary CCA nucleotides to the 3′ end of pre-tRNAs was observed in cells shifted to unfavourable growth conditions. This effect was reduced by overexpression of the yeast CCA1 gene encoding ATP(CTP):tRNA nucleotidyltransferase. The CCA sequence at the 3′ end is important for export of tRNA precursors from the nucleus and essential for tRNA charging with amino acids. Data presented here indicate that CCA-addition to intron-containing end-processed tRNA precursors is a limiting step in tRNA maturation when there is no Maf1 mediated RNA polymerase III (Pol III) repression. The correlation between CCA synthesis and Pol III regulation by Maf1 could be important in coordination of tRNA transcription, processing and regulation of translation. Effect of Maf1 on maturation of tRNA precursors was analysed in yeast cells. CCA addition to the 3′ end of pre-tRNA was down-regulated in maf1Δ mutant under stress. Effect of inactivation and overproduction of Cca1 enzyme in maf1Δ cells was examined. Link between CCA synthesis and RNA polymerase III regulation is discussed.
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Affiliation(s)
- Dominika Foretek
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Przemysław Nuc
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - Marek Żywicki
- Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - Wojciech M Karlowski
- Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - Grzegorz Kudla
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, Scotland, UK
| | - Magdalena Boguta
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
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21
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Turowski TW, Leśniewska E, Delan-Forino C, Sayou C, Boguta M, Tollervey D. Global analysis of transcriptionally engaged yeast RNA polymerase III reveals extended tRNA transcripts. Genome Res 2016; 26:933-44. [PMID: 27206856 PMCID: PMC4937561 DOI: 10.1101/gr.205492.116] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/20/2016] [Indexed: 01/25/2023]
Abstract
RNA polymerase III (RNAPIII) synthesizes a range of highly abundant small stable RNAs, principally pre-tRNAs. Here we report the genome-wide analysis of nascent transcripts attached to RNAPIII under permissive and restrictive growth conditions. This revealed strikingly uneven polymerase distributions across transcription units, generally with a predominant 5' peak. This peak was higher for more heavily transcribed genes, suggesting that initiation site clearance is rate-limiting during RNAPIII transcription. Down-regulation of RNAPIII transcription under stress conditions was found to be uneven; a subset of tRNA genes showed low response to nutrient shift or loss of the major transcription regulator Maf1, suggesting potential "housekeeping" roles. Many tRNA genes were found to generate long, 3'-extended forms due to read-through of the canonical poly(U) terminators. The degree of read-through was anti-correlated with the density of U-residues in the nascent tRNA, and multiple, functional terminators can be located far downstream. The steady-state levels of 3'-extended pre-tRNA transcripts are low, apparently due to targeting by the nuclear surveillance machinery, especially the RNA binding protein Nab2, cofactors for the nuclear exosome, and the 5'-exonuclease Rat1.
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Affiliation(s)
- Tomasz W Turowski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland; Institute of Biotechnology, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland
| | - Ewa Leśniewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Clementine Delan-Forino
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland
| | - Camille Sayou
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland
| | - Magdalena Boguta
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland
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22
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Abstract
Long terminal repeat (LTR) retrotransposons constitute significant fractions of many eukaryotic genomes. Two ancient families are Ty1/Copia (Pseudoviridae) and Ty3/Gypsy (Metaviridae). The Ty3/Gypsy family probably gave rise to retroviruses based on the domain order, similarity of sequences, and the envelopes encoded by some members. The Ty3 element of Saccharomyces cerevisiae is one of the most completely characterized elements at the molecular level. Ty3 is induced in mating cells by pheromone stimulation of the mitogen-activated protein kinase pathway as cells accumulate in G1. The two Ty3 open reading frames are translated into Gag3 and Gag3-Pol3 polyprotein precursors. In haploid mating cells Gag3 and Gag3-Pol3 are assembled together with Ty3 genomic RNA into immature virus-like particles in cellular foci containing RNA processing body proteins. Virus-like particle Gag3 is then processed by Ty3 protease into capsid, spacer, and nucleocapsid, and Gag3-Pol3 into those proteins and additionally, protease, reverse transcriptase, and integrase. After haploid cells mate and become diploid, genomic RNA is reverse transcribed into cDNA. Ty3 integration complexes interact with components of the RNA polymerase III transcription complex resulting in Ty3 integration precisely at the transcription start site. Ty3 activation during mating enables proliferation of Ty3 between genomes and has intriguing parallels with metazoan retrotransposon activation in germ cell lineages. Identification of nuclear pore, DNA replication, transcription, and repair host factors that affect retrotransposition has provided insights into how hosts and retrotransposons interact to balance genome stability and plasticity.
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23
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Abstract
The transfer of genetic information from RNA to DNA is considered an extraordinary process in molecular biology. Despite the fact that cells transcribe abundant amount of RNA with a wide range of functions, it has been difficult to uncover whether RNA can serve as a template for DNA repair and recombination. An increasing number of experimental evidences suggest a direct role of RNA in DNA modification. Recently, we demonstrated that endogenous transcript RNA can serve as a template to repair a DNA double-strand break (DSB), the most harmful DNA lesion, not only indirectly via formation of a DNA copy (cDNA) intermediate, but also directly in a homology driven mechanism in budding yeast. These results point out that the transfer of genetic information from RNA to DNA is more general than previously thought. We found that transcript RNA is more efficient in repairing a DSB in its own DNA (in cis) than in a homologous but ectopic locus (in trans). Here, we summarize current knowledge about the process of RNA-driven DNA repair and recombination, and provide further data in support of our model of DSB repair by transcript RNA in cis. We show that a DSB is precisely repaired predominately by transcript RNA and not by residual cDNA in conditions in which formation of cDNA by reverse transcription is inhibited. Additionally, we demonstrate that defects in ribonuclease (RNase) H stimulate precise DSB repair by homologous RNA or cDNA sequence, and not by homologous DNA sequence carried on a plasmid. These results highlight an antagonistic role of RNase H in RNA-DNA recombination. Ultimately, we discuss several questions that should be addressed to better understand mechanisms and implications of RNA-templated DNA repair and recombination.
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Affiliation(s)
- Havva Keskin
- a School of Biology, Georgia Institute of Technology , Atlanta , Georgia , USA
| | - Chance Meers
- a School of Biology, Georgia Institute of Technology , Atlanta , Georgia , USA
| | - Francesca Storici
- a School of Biology, Georgia Institute of Technology , Atlanta , Georgia , USA
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24
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Karlsborn T, Tükenmez H, Mahmud AKMF, Xu F, Xu H, Byström AS. Elongator, a conserved complex required for wobble uridine modifications in eukaryotes. RNA Biol 2015; 11:1519-28. [PMID: 25607684 DOI: 10.4161/15476286.2014.992276] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Elongator is a 6 subunit protein complex highly conserved in eukaryotes. The role of this complex has been controversial as the pleiotropic phenotypes of Elongator mutants have implicated the complex in several cellular processes. However, in yeast there is convincing evidence that the primary and probably only role of this complex is in formation of the 5-methoxycarbonylmethyl (mcm(5)) and 5-carbamoylmethyl (ncm(5)) side chains on uridines at wobble position in tRNA. In this review we summarize the cellular processes that have been linked to the Elongator complex and discuss its role in tRNA modification and regulation of translation. We also describe additional gene products essential for formation of ncm(5) and mcm(5) side chains at U34 and their influence on Elongator activity.
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Affiliation(s)
- Tony Karlsborn
- a Department of Molecular Biology ; Umeå University; Umeå , Sweden
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25
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Abstract
Long-terminal repeat (LTR)-retrotransposons generate a copy of their DNA (cDNA) by reverse transcription of their RNA genome in cytoplasmic nucleocapsids. They are widespread in the eukaryotic kingdom and are the evolutionary progenitors of retroviruses [1]. The Ty1 element of the budding yeast Saccharomyces cerevisiae was the first LTR-retrotransposon demonstrated to mobilize through an RNA intermediate, and not surprisingly, is the best studied. The depth of our knowledge of Ty1 biology stems not only from the predominance of active Ty1 elements in the S. cerevisiae genome but also the ease and breadth of genomic, biochemical and cell biology approaches available to study cellular processes in yeast. This review describes the basic structure of Ty1 and its gene products, the replication cycle, the rapidly expanding compendium of host co-factors known to influence retrotransposition and the nature of Ty1's elaborate symbiosis with its host. Our goal is to illuminate the value of Ty1 as a paradigm to explore the biology of LTR-retrotransposons in multicellular organisms, where the low frequency of retrotransposition events presents a formidable barrier to investigations of retrotransposon biology.
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26
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Ho KL, Ma L, Cheung S, Manhas S, Fang N, Wang K, Young B, Loewen C, Mayor T, Measday V. A role for the budding yeast separase, Esp1, in Ty1 element retrotransposition. PLoS Genet 2015; 11:e1005109. [PMID: 25822502 PMCID: PMC4378997 DOI: 10.1371/journal.pgen.1005109] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 02/27/2015] [Indexed: 12/18/2022] Open
Abstract
Separase/Esp1 is a protease required at the onset of anaphase to cleave cohesin and thereby enable sister chromatid separation. Esp1 also promotes release of the Cdc14 phosphatase from the nucleolus to enable mitotic exit. To uncover other potential roles for separase, we performed two complementary genome-wide genetic interaction screens with a strain carrying the budding yeast esp1-1 separase mutation. We identified 161 genes that when mutated aggravate esp1-1 growth and 44 genes that upon increased dosage are detrimental to esp1-1 viability. In addition to the expected cell cycle and sister chromatid segregation genes that were identified, 24% of the genes identified in the esp1-1 genetic screens have a role in Ty1 element retrotransposition. Retrotransposons, like retroviruses, replicate through reverse transcription of an mRNA intermediate and the resultant cDNA product is integrated into the genome by a conserved transposon or retrovirus encoded integrase protein. We purified Esp1 from yeast and identified an interaction between Esp1 and Ty1 integrase using mass spectrometry that was subsequently confirmed by co-immunoprecipitation analysis. Ty1 transposon mobility and insertion upstream of the SUF16 tRNA gene are both reduced in an esp1-1 strain but increased in cohesin mutant strains. Securin/Pds1, which is required for efficient localization of Esp1 to the nucleus, is also required for efficient Ty1 transposition. We propose that Esp1 serves two roles to mediate Ty1 transposition - one to remove cohesin and the second to target Ty1-IN to chromatin.
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Affiliation(s)
- Krystina L. Ho
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Wine Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lina Ma
- Wine Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephanie Cheung
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Wine Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Savrina Manhas
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Wine Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nancy Fang
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kaiqian Wang
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Wine Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Barry Young
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher Loewen
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Thibault Mayor
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vivien Measday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Wine Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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27
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Koh KD, Balachander S, Hesselberth JR, Storici F. Ribose-seq: global mapping of ribonucleotides embedded in genomic DNA. Nat Methods 2015; 12:251-7, 3 p following 257. [PMID: 25622106 DOI: 10.1038/nmeth.3259] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/22/2014] [Indexed: 02/06/2023]
Abstract
Abundant ribonucleotide incorporation in DNA during replication and repair has profound consequences for genome stability, but the global distribution of ribonucleotide incorporation is unknown. We developed ribose-seq, a method for capturing unique products generated by alkaline cleavage of DNA at embedded ribonucleotides. High-throughput sequencing of these fragments in DNA from the yeast Saccharomyces cerevisiae revealed widespread ribonucleotide distribution, with a strong preference for cytidine and guanosine, and identified hotspots of ribonucleotide incorporation in nuclear and mitochondrial DNA. Ribonucleotides were primarily incorporated on the newly synthesized leading strand of nuclear DNA and were present upstream of (G+C)-rich tracts in the mitochondrial genome. Ribose-seq is a powerful tool for the systematic profiling of ribonucleotide incorporation in genomic DNA.
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Affiliation(s)
- Kyung Duk Koh
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Sathya Balachander
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Jay R Hesselberth
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, Colorado, USA
| | - Francesca Storici
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
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Zhou XL, Ruan ZR, Wang M, Fang ZP, Wang Y, Chen Y, Liu RJ, Eriani G, Wang ED. A minimalist mitochondrial threonyl-tRNA synthetase exhibits tRNA-isoacceptor specificity during proofreading. Nucleic Acids Res 2014; 42:13873-86. [PMID: 25414329 PMCID: PMC4267643 DOI: 10.1093/nar/gku1218] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Yeast mitochondria contain a minimalist threonyl-tRNA synthetase (ThrRS) composed only of the catalytic core and tRNA binding domain but lacking the entire editing domain. Besides the usual tRNAThr2, some budding yeasts, such as Saccharomyces cerevisiae, also contain a non-canonical tRNAThr1 with an enlarged 8-nucleotide anticodon loop, reprograming the usual leucine CUN codons to threonine. This raises interesting questions about the aminoacylation fidelity of such ThrRSs and the possible contribution of the two tRNAThrs during editing. Here, we found that, despite the absence of the editing domain, S. cerevisiae mitochondrial ThrRS (ScmtThrRS) harbors a tRNA-dependent pre-transfer editing activity. Remarkably, only the usual tRNAThr2 stimulated pre-transfer editing, thus, establishing the first example of a synthetase exhibiting tRNA-isoacceptor specificity during pre-transfer editing. We also showed that the failure of tRNAThr1 to stimulate tRNA-dependent pre-transfer editing was due to the lack of an editing domain. Using assays of the complementation of a ScmtThrRS gene knockout strain, we showed that the catalytic core and tRNA binding domain of ScmtThrRS co-evolved to recognize the unusual tRNAThr1. In combination, the results provide insights into the tRNA-dependent editing process and suggest that tRNA-dependent pre-transfer editing takes place in the aminoacylation catalytic core.
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Affiliation(s)
- Xiao-Long Zhou
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China
| | - Zhi-Rong Ruan
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China
| | - Meng Wang
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China
| | - Zhi-Peng Fang
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China
| | - Yong Wang
- School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, 200031 Shanghai, China
| | - Yun Chen
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China
| | - Ru-Juan Liu
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China
| | - Gilbert Eriani
- Architecture et Réactivité de l'ARN, Université de Strasbourg, UPR9002 CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg, France
| | - En-Duo Wang
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, 200031 Shanghai, China
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Tarrant D, von der Haar T. Synonymous codons, ribosome speed, and eukaryotic gene expression regulation. Cell Mol Life Sci 2014; 71:4195-206. [PMID: 25038778 PMCID: PMC11113527 DOI: 10.1007/s00018-014-1684-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 06/26/2014] [Accepted: 07/14/2014] [Indexed: 12/27/2022]
Abstract
Quantitative control of gene expression occurs at multiple levels, including the level of translation. Within the overall process of translation, most identified regulatory processes impinge on the initiation phase. However, recent studies have revealed that the elongation phase can also regulate translation if elongation and initiation occur with specific, not mutually compatible rate parameters. Translation elongation then limits the overall amount of protein that can be made from an mRNA. Several recently discovered control mechanisms of biological pathways are based on such elongation control. Here, we review the molecular mechanisms that determine ribosome speed in eukaryotic organisms, and discuss under which conditions ribosome speed can become the controlling parameter of gene expression levels.
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Affiliation(s)
- Daniel Tarrant
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, CT2 7NJ UK
| | - Tobias von der Haar
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, CT2 7NJ UK
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New developments of RNAi in Paracoccidioides brasiliensis: prospects for high-throughput, genome-wide, functional genomics. PLoS Negl Trop Dis 2014; 8:e3173. [PMID: 25275433 PMCID: PMC4183473 DOI: 10.1371/journal.pntd.0003173] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 08/06/2014] [Indexed: 01/11/2023] Open
Abstract
Background The Fungal Genome Initiative of the Broad Institute, in partnership with the Paracoccidioides research community, has recently sequenced the genome of representative isolates of this human-pathogen dimorphic fungus: Pb18 (S1), Pb03 (PS2) and Pb01. The accomplishment of future high-throughput, genome-wide, functional genomics will rely upon appropriate molecular tools and straightforward techniques to streamline the generation of stable loss-of-function phenotypes. In the past decades, RNAi has emerged as the most robust genetic technique to modulate or to suppress gene expression in diverse eukaryotes, including fungi. These molecular tools and techniques, adapted for RNAi, were up until now unavailable for P. brasiliensis. Methodology/Principal Findings In this paper, we report Agrobacterium tumefaciens mediated transformation of yeast cells for high-throughput applications with which higher transformation frequencies of 150±24 yeast cell transformants per 1×106 viable yeast cells were obtained. Our approach is based on a bifunctional selective marker fusion protein consisted of the Streptoalloteichus hindustanus bleomycin-resistance gene (Shble) and the intrinsically fluorescent monomeric protein mCherry which was codon-optimized for heterologous expression in P. brasiliensis. We also report successful GP43 gene knock-down through the expression of intron-containing hairpin RNA (ihpRNA) from a Gateway-adapted cassette (cALf) which was purpose-built for gene silencing in a high-throughput manner. Gp43 transcript levels were reduced by 73.1±22.9% with this approach. Conclusions/Significance We have a firm conviction that the genetic transformation technique and the molecular tools herein described will have a relevant contribution in future Paracoccidioides spp. functional genomics research. Diverse eukaryotes, including various fungi, utilize RNA interference (RNAi) pathways to regulate genome-wide gene expression. Since the initial characterization of these pathways and the demonstration of its artificial induction in the filamentous ascomycete Neurospora crassa, RNAi has emerged as the most robust reverse-genetic technique to scrutinize the function of genes and has been increasingly adopted in high-throughput functional genomics in search of new insights into fungal pathobiology. Herein, we have developed appropriate molecular tools and straightforward techniques to streamline the generation of stable loss-of-function phenotypes for the human-pathogen Paracoccidioides brasiliensis, which is phylogenetically related to Blastomyces dermatitidis, Coccidioides immitis and Histoplasma capsulatum. Likewise these thermo-dimorphic fungi, P. brasiliensis infection in immunocompetent or immunocompromised individuals ensue in a life-threatening systemic mycosis known as Paracoccidioidomycosis.
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Smaldino PJ, Read DF, Pratt-Hyatt M, Hopper AK, Engelke DR. The cytoplasmic and nuclear populations of the eukaryote tRNA-isopentenyl transferase have distinct functions with implications in human cancer. Gene 2014; 556:13-8. [PMID: 25261850 DOI: 10.1016/j.gene.2014.09.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 09/22/2014] [Accepted: 09/23/2014] [Indexed: 12/29/2022]
Abstract
Mod5 is the yeast tRNA isopentenyl transferase, an enzyme that is conserved from bacteria to humans. Mod5 is primarily cytoplasmic where it modifies the A37 position of a few tRNAs, and the yeast enzyme has been shown capable of forming heritable, amyloid-like aggregates that confer a selective advantage in the presence of specific antifungal agents. A subpopulation of Mod5 is also found associated with nuclear tRNA genes, where it contributes tRNA-gene mediated (tgm) silencing of local transcription by RNA polymerase II. The tgm-silencing function of Mod5 has been observed in yeast and a Mod5-deletion in yeast can be complemented by the plant and human tRNA isopentenyl transferases, but not the bacterial enzymes, possibly due to the lack of an extended C-terminal domain found in eukaryotes. In light of this additional nuclear role for Mod5 we discuss the proposed role of the human homologue of Mod5, TRIT1, as a tumor suppressor protein.
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Affiliation(s)
- P J Smaldino
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
| | - D F Read
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - M Pratt-Hyatt
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; The Great Plains Laboratory, 11813W. 77th St. Lenexa KS 66214, USA
| | - A K Hopper
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - D R Engelke
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
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Swartz D, Mok L, Botta S, Singh A, Altenberg G, Urbatsch I. Directed evolution of P-glycoprotein cysteines reveals site-specific, non-conservative substitutions that preserve multidrug resistance. Biosci Rep 2014; 34:e00116. [PMID: 24825346 PMCID: PMC4069687 DOI: 10.1042/bsr20140062] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/05/2014] [Accepted: 05/06/2014] [Indexed: 11/21/2022] Open
Abstract
Pgp (P-glycoprotein) is a prototype ABC (ATP-binding-cassette) transporter involved in multidrug resistance of cancer. We used directed evolution to replace six cytoplasmic Cys (cysteine) residues in Pgp with all 20 standard amino acids and selected for active mutants. From a pool of 75000 transformants for each block of three Cys, we identified multiple mutants that preserved drug resistance and yeast mating activity. The most frequent substitutions were glycine and serine for Cys427 (24 and 20%, respectively) and Cys1070 (37 and 25%) of the Walker A motifs in the NBDs (nucleotide-binding domains), Cys1223 in NBD2 (25 and 8%) and Cys638 in the linker region (24 and 16%), whereas close-by Cys669 tolerated glycine (16%) and alanine (14%), but not serine (absent). Cys1121 in NBD2 showed a clear preference for positively charged arginine (38%) suggesting a salt bridge with Glu269 in the ICL2 (intracellular loop 2) may stabilize domain interactions. In contrast, three Cys residues in transmembrane α-helices could be successfully replaced by alanine. The resulting CL (Cys-less) Pgp was fully active in yeast cells, and purified proteins displayed drug-stimulated ATPase activities indistinguishable from WT (wild-type) Pgp. Overall, directed evolution identified site-specific, non-conservative Cys substitutions that allowed building of a robust CL Pgp, an invaluable new tool for future functional and structural studies, and that may guide the construction of other CL proteins where alanine and serine have proven unsuccessful.
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Key Words
- abc transporter
- multidrug transporter
- non-conservative cysteine substitutions
- protein evolution site-saturation mutagenesis
- yeast drug resistance
- abc, atp-binding-cassette
- cftr, cystic fibrosis transmembrane conductance regulator
- cl, cys-less
- cp-mts, 7-diethylamino-3-(4′-maleimidylphenyl)-4-methylcoumarin
- ddm, n-dodecyl-β-d-maltopyranoside
- icl, intracellular loop
- nbd, nucleotide-binding domain
- pgp, p-glycoprotein
- sec, size exclusion chromatography
- tmd, transmembrane domain
- wt, wild-type
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Affiliation(s)
- Douglas J. Swartz
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Leo Mok
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Sri K. Botta
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Anukriti Singh
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Guillermo A. Altenberg
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- ‡Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Ina L. Urbatsch
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
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Soma A. Circularly permuted tRNA genes: their expression and implications for their physiological relevance and development. Front Genet 2014; 5:63. [PMID: 24744771 PMCID: PMC3978253 DOI: 10.3389/fgene.2014.00063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/12/2014] [Indexed: 12/02/2022] Open
Abstract
A number of genome analyses and searches using programs that focus on the RNA-specific bulge-helix-bulge (BHB) motif have uncovered a wide variety of disrupted tRNA genes. The results of these analyses have shown that genetic information encoding functional RNAs is described in the genome cryptically and is retrieved using various strategies. One such strategy is represented by circularly permuted tRNA genes, in which the sequences encoding the 5′-half and 3′-half of the specific tRNA are separated and inverted on the genome. Biochemical analyses have defined a processing pathway in which the termini of tRNA precursors (pre-tRNAs) are ligated to form a characteristic circular RNA intermediate, which is then cleaved at the acceptor-stem to generate the typical cloverleaf structure with functional termini. The sequences adjacent to the processing site located between the 3′-half and the 5′-half of pre-tRNAs potentially form a BHB motif, which is the dominant recognition site for the tRNA-intron splicing endonuclease, suggesting that circularization of pre-tRNAs depends on the splicing machinery. Some permuted tRNAs contain a BHB-mediated intron in their 5′- or 3′-half, meaning that removal of an intron, as well as swapping of the 5′- and 3′-halves, are required during maturation of their pre-tRNAs. To date, 34 permuted tRNA genes have been identified from six species of unicellular algae and one archaeon. Although their physiological significance and mechanism of development remain unclear, the splicing system of BHB motifs seems to have played a key role in the formation of permuted tRNA genes. In this review, current knowledge of circularly permuted tRNA genes is presented and some unanswered questions regarding these species are discussed.
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Affiliation(s)
- Akiko Soma
- Graduate School of Horticulture, Chiba University Matsudo, Japan
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Michely S, Toulza E, Subirana L, John U, Cognat V, Maréchal-Drouard L, Grimsley N, Moreau H, Piganeau G. Evolution of codon usage in the smallest photosynthetic eukaryotes and their giant viruses. Genome Biol Evol 2013; 5:848-59. [PMID: 23563969 PMCID: PMC3673656 DOI: 10.1093/gbe/evt053] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Prasinoviruses are among the largest viruses (>200 kb) and encode several hundreds of
protein coding genes, including most genes of the DNA replication machinery and several
genes involved in transcription and translation, as well as transfer RNAs (tRNAs). They
can infect and lyse small eukaryotic planktonic marine green algae, thereby affecting
global algal population dynamics. Here, we investigate the causes of codon usage bias
(CUB) in one prasinovirus, OtV5, and its host Ostreococcus tauri, during
a viral infection using microarray expression data. We show that 1) CUB in the host and in
the viral genes increases with expression levels and 2) optimal codons use those tRNAs
encoded by the most abundant host tRNA genes, supporting the notion of translational
optimization by natural selection. We find evidence that viral tRNA genes complement the
host tRNA pool for those viral amino acids whose host tRNAs are in short supply. We
further discuss the coevolution of CUB in hosts and prasinoviruses by comparing optimal
codons in three evolutionary diverged host–virus-specific pairs whose complete
genome sequences are known.
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Affiliation(s)
- Stephanie Michely
- UPMC Univ Paris 06, UMR7232, BIOM, Observatoire Océanologique, F-66650, Banyuls-sur-Mer, France
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Transcriptome surveillance by selective termination of noncoding RNA synthesis. Cell 2013; 155:1075-87. [PMID: 24210918 DOI: 10.1016/j.cell.2013.10.024] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/12/2013] [Accepted: 10/03/2013] [Indexed: 12/22/2022]
Abstract
Pervasive transcription of eukaryotic genomes stems to a large extent from bidirectional promoters that synthesize mRNA and divergent noncoding RNA (ncRNA). Here, we show that ncRNA transcription in the yeast S. cerevisiae is globally restricted by early termination that relies on the essential RNA-binding factor Nrd1. Depletion of Nrd1 from the nucleus results in 1,526 Nrd1-unterminated transcripts (NUTs) that originate from nucleosome-depleted regions (NDRs) and can deregulate mRNA synthesis by antisense repression and transcription interference. Transcriptome-wide Nrd1-binding maps reveal divergent NUTs at most promoters and antisense NUTs in most 3' regions of genes. Nrd1 and its partner Nab3 preferentially bind RNA motifs that are depleted in mRNAs and enriched in ncRNAs and some mRNAs whose synthesis is controlled by transcription attenuation. These results define a global mechanism for transcriptome surveillance that selectively terminates ncRNA synthesis to provide promoter directionality and to suppress antisense transcription.
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Bleykasten-Grosshans C, Friedrich A, Schacherer J. Genome-wide analysis of intraspecific transposon diversity in yeast. BMC Genomics 2013; 14:399. [PMID: 23768249 PMCID: PMC4022208 DOI: 10.1186/1471-2164-14-399] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 06/06/2013] [Indexed: 02/02/2023] Open
Abstract
Background In the model organism Saccharomyces cerevisiae, the transposable elements (TEs) consist of LTR (Long Terminal Repeat) retrotransposons called Ty elements belonging to five families, Ty1 to Ty5. They take the form of either full-length coding elements or non-coding solo-LTRs corresponding to remnants of former transposition events. Although the biological features of Ty elements have been studied in detail in S. cerevisiae and the Ty content of the reference strain (S288c) was accurately annotated, the Ty-related intra-specific diversity has not been closely investigated so far. Results In this study, we investigated the Ty contents of 41 available genomes of isolated S. cerevisiae strains of diverse geographical and ecological origins. The strains were compared in terms of the number of Ty copies, the content of the potential transpositionally active elements and the genomic insertion maps. The strain repertoires were also investigated in the closely related Ty1 and Ty2 families and subfamilies. Conclusions This is the first genome-wide analysis of the diversity associated to the Ty elements, carried out for a large set of S. cerevisiae strains. The results of the present analyses suggest that the current Ty-related polymorphism has resulted from multiple causes such as differences between strains, between Ty families and over time, in the recent transpositional activity of Ty elements. Some new Ty1 variants were also identified, and we have established that Ty1 variants have different patterns of distribution among strains, which further contributes to the strain diversity.
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Affiliation(s)
- Claudine Bleykasten-Grosshans
- CNRS, Department of Genetics, Genomics and Microbiology, University of Strasbourg, UMR 7156, 28, rue Goethe, Strasbourg, 67083, France.
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Carr M, Bensasson D, Bergman CM. Evolutionary genomics of transposable elements in Saccharomyces cerevisiae. PLoS One 2012; 7:e50978. [PMID: 23226439 PMCID: PMC3511429 DOI: 10.1371/journal.pone.0050978] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/31/2012] [Indexed: 11/18/2022] Open
Abstract
Saccharomyces cerevisiae is one of the premier model systems for studying the genomics and evolution of transposable elements. The availability of the S. cerevisiae genome led to unprecedented insights into its five known transposable element families (the LTR retrotransposons Ty1-Ty5) in the years shortly after its completion. However, subsequent advances in bioinformatics tools for analysing transposable elements and the recent availability of genome sequences for multiple strains and species of yeast motivates new investigations into Ty evolution in S. cerevisiae. Here we provide a comprehensive phylogenetic and population genetic analysis of all Ty families in S. cerevisiae based on a systematic re-annotation of Ty elements in the S288c reference genome. We show that previous annotation efforts have underestimated the total copy number of Ty elements for all known families. In addition, we identify a new family of Ty3-like elements related to the S. paradoxus Ty3p which is composed entirely of degenerate solo LTRs. Phylogenetic analyses of LTR sequences identified three families with short-branch, recently active clades nested among long branch, inactive insertions (Ty1, Ty3, Ty4), one family with essentially all recently active elements (Ty2) and two families with only inactive elements (Ty3p and Ty5). Population genomic data from 38 additional strains of S. cerevisiae show that the majority of Ty insertions in the S288c reference genome are fixed in the species, with insertions in active clades being predominantly polymorphic and insertions in inactive clades being predominantly fixed. Finally, we use comparative genomic data to provide evidence that the Ty2 and Ty3p families have arisen in the S. cerevisiae genome by horizontal transfer. Our results demonstrate that the genome of a single individual contains important information about the state of TE population dynamics within a species and suggest that horizontal transfer may play an important role in shaping the genomic diversity of transposable elements in unicellular eukaryotes.
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Affiliation(s)
- Martin Carr
- School of Applied Sciences, University of Huddersfield, West Yorkshire, UK.
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Abstract
Translation in baker’s yeast involves the coordinated interaction of 200 000 ribosomes, 3 000 000 tRNAs and between 15 000 and 60 000 mRNAs. It is currently unknown whether this specific constellation of components has particular relevance for the requirements of the yeast proteome, or whether this is simply a frozen accident. Our study uses a computational simulation model of the genome-wide translational apparatus of yeast to explore quantitatively which combinations of mRNAs, ribosomes and tRNAs can produce viable proteomes. Surprisingly, we find that if we only consider total translational activity over time without regard to composition of the proteome, then there are many and widely differing combinations that can generate equivalent synthesis yields. In contrast, translational activity required for generating specific proteomes can only be achieved within a much more constrained parameter space. Furthermore, we find that strongly ribosome limited regimes are optimal for cells in that they are resource efficient and simplify the dynamics of the system.
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Affiliation(s)
- Dominique Chu
- School of Computing, University of Kent, CT2 7NF Canterbury, UK.
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Qi X, Daily K, Nguyen K, Wang H, Mayhew D, Rigor P, Forouzan S, Johnston M, Mitra RD, Baldi P, Sandmeyer S. Retrotransposon profiling of RNA polymerase III initiation sites. Genome Res 2012; 22:681-92. [PMID: 22287102 DOI: 10.1101/gr.131219.111] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Although retroviruses are relatively promiscuous in choice of integration sites, retrotransposons can display marked integration specificity. In yeast and slime mold, some retrotransposons are associated with tRNA genes (tDNAs). In the Saccharomyces cerevisiae genome, the long terminal repeat retrotransposon Ty3 is found at RNA polymerase III (Pol III) transcription start sites of tDNAs. Ty1, 2, and 4 elements also cluster in the upstream regions of these genes. To determine the extent to which other Pol III-transcribed genes serve as genomic targets for Ty3, a set of 10,000 Ty3 genomic retrotranspositions were mapped using high-throughput DNA sequencing. Integrations occurred at all known tDNAs, two tDNA relics (iYGR033c and ZOD1), and six non-tDNA, Pol III-transcribed types of genes (RDN5, SNR6, SNR52, RPR1, RNA170, and SCR1). Previous work in vitro demonstrated that the Pol III transcription factor (TF) IIIB is important for Ty3 targeting. However, seven loci that bind the TFIIIB loader, TFIIIC, were not targeted, underscoring the unexplained absence of TFIIIB at those sites. Ty3 integrations also occurred in two open reading frames not previously associated with Pol III transcription, suggesting the existence of a small number of additional sites in the yeast genome that interact with Pol III transcription complexes.
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Affiliation(s)
- Xiaojie Qi
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, California 92697, USA
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A gene optimization strategy that enhances production of fully functional P-glycoprotein in Pichia pastoris. PLoS One 2011; 6:e22577. [PMID: 21826197 PMCID: PMC3149604 DOI: 10.1371/journal.pone.0022577] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Accepted: 06/24/2011] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Structural and biochemical studies of mammalian membrane proteins remain hampered by inefficient production of pure protein. We explored codon optimization based on highly expressed Pichia pastoris genes to enhance co-translational folding and production of P-glycoprotein (Pgp), an ATP-dependent drug efflux pump involved in multidrug resistance of cancers. METHODOLOGY/PRINCIPAL FINDINGS Codon-optimized "Opti-Pgp" and wild-type Pgp, identical in primary protein sequence, were rigorously analyzed for differences in function or solution structure. Yeast expression levels and yield of purified protein from P. pastoris (∼130 mg per kg cells) were about three-fold higher for Opti-Pgp than for wild-type protein. Opti-Pgp conveyed full in vivo drug resistance against multiple anticancer and fungicidal drugs. ATP hydrolysis by purified Opti-Pgp was strongly stimulated ∼15-fold by verapamil and inhibited by cyclosporine A with binding constants of 4.2±2.2 µM and 1.1±0.26 µM, indistinguishable from wild-type Pgp. Maximum turnover number was 2.1±0.28 µmol/min/mg and was enhanced by 1.2-fold over wild-type Pgp, likely due to higher purity of Opti-Pgp preparations. Analysis of purified wild-type and Opti-Pgp by CD, DSC and limited proteolysis suggested similar secondary and ternary structure. Addition of lipid increased the thermal stability from T(m) ∼40 °C to 49 °C, and the total unfolding enthalpy. The increase in folded state may account for the increase in drug-stimulated ATPase activity seen in presence of lipids. CONCLUSION The significantly higher yields of protein in the native folded state, higher purity and improved function establish the value of our gene optimization approach, and provide a basis to improve production of other membrane proteins.
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Bleykasten-Grosshans C, Neuvéglise C. Transposable elements in yeasts. C R Biol 2011; 334:679-86. [PMID: 21819950 DOI: 10.1016/j.crvi.2011.05.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 03/31/2011] [Indexed: 11/19/2022]
Abstract
With the development of new sequencing technologies in the past decade, yeast genomes have been extensively sequenced and their structures investigated. Transposable elements (TEs) are ubiquitous in eukaryotes and constitute a limited part of yeast genomes. However, due to their ability to move in genomes and generate dispersed repeated sequences, they contribute to modeling yeast genomes and thereby induce plasticity. This review assesses the TE contents of yeast genomes investigated so far. Their diversity and abundance at the inter- and intraspecific levels are presented, and their effects on gene expression and genome stability is considered. Recent results concerning TE-host interactions are also analyzed.
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Affiliation(s)
- Claudine Bleykasten-Grosshans
- CNRS UMR 7156, Laboratoire Génétique Moléculaire Génomique Microbiologie, Université de Strasbourg, 28 rue Goethe, 67083 Strasbourg cedex, France.
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42
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Chu D, Barnes DJ, von der Haar T. The role of tRNA and ribosome competition in coupling the expression of different mRNAs in Saccharomyces cerevisiae. Nucleic Acids Res 2011; 39:6705-14. [PMID: 21558172 PMCID: PMC3159466 DOI: 10.1093/nar/gkr300] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Protein synthesis translates information from messenger RNAs into functional proteomes. Because of the finite nature of the resources required by the translational machinery, both the overall protein synthesis activity of a cell and activity on individual mRNAs are controlled by the allocation of limiting resources. Upon introduction of heterologous sequences into an organism—for example for the purposes of bioprocessing or synthetic biology—limiting resources may also become overstretched, thus negatively affecting both endogenous and heterologous gene expression. In this study, we present a mean-field model of translation in Saccharomyces cerevisiae for the investigation of two particular translational resources, namely ribosomes and aminoacylated tRNAs. We firstly use comparisons of experiments with heterologous sequences and simulations of the same conditions to calibrate our model, and then analyse the behaviour of the translational system in yeast upon introduction of different types of heterologous sequences. Our main findings are that: competition for ribosomes, rather than tRNAs, limits global translation in this organism; that tRNA aminoacylation levels exert, at most, weak control over translational activity; and that decoding speeds and codon adaptation exert strong control over local (mRNA specific) translation rates.
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Affiliation(s)
- Dominique Chu
- School of Computing, University of Kent, CT2 7NF, UK.
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Behura SK, Stanke M, Desjardins CA, Werren JH, Severson DW. Comparative analysis of nuclear tRNA genes of Nasonia vitripennis and other arthropods, and relationships to codon usage bias. INSECT MOLECULAR BIOLOGY 2010; 19 Suppl 1:49-58. [PMID: 20167017 PMCID: PMC4046259 DOI: 10.1111/j.1365-2583.2009.00933.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Using bioinformatics methods, we identified a total of 221 and 199 tRNA genes in the nuclear genomes of Nasonia vitripennis and honey bee (Apis mellifera), respectively. We performed comparative analyses of Nasonia tRNA genes with honey bee and other selected insects to understand genomic distribution, sequence evolution and relationship of tRNA copy number with codon usage patterns. Many tRNA genes are located physically close to each other in the form of small clusters in the Nasonia genome. However, the number of clusters and the tRNA genes that form such clusters vary from species to species. In particular, the Ala-, Pro-, Tyr- and His-tRNA genes tend to accumulate in clusters in Nasonia but not in honey bee, whereas the bee contains a long cluster of 15 tRNA genes (of which 13 are Gln-tRNAs) that is absent in Nasonia. Though tRNA genes are highly conserved, contrasting patterns of nucleotide diversity are observed among the arm and loop regions of tRNAs between Nasonia and honey bee. Also, the sequence convergence between the reconstructed ancestral tRNAs and the present day tRNAs suggests a common ancestral origin of Nasonia and honey bee tRNAs. Furthermore, we also present evidence that the copy number of isoacceptor tRNAs (those having a different anticodon but charge the same amino acid) is correlated with codon usage patterns of highly expressed genes in Nasonia.
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Affiliation(s)
- S K Behura
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
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De Schutter K, Lin YC, Tiels P, Van Hecke A, Glinka S, Weber-Lehmann J, Rouzé P, Van de Peer Y, Callewaert N. Genome sequence of the recombinant protein production host Pichia pastoris. Nat Biotechnol 2009; 27:561-6. [PMID: 19465926 DOI: 10.1038/nbt.1544] [Citation(s) in RCA: 388] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 05/06/2009] [Indexed: 01/19/2023]
Abstract
The methylotrophic yeast Pichia pastoris is widely used for the production of proteins and as a model organism for studying peroxisomal biogenesis and methanol assimilation. P. pastoris strains capable of human-type N-glycosylation are now available, which increases the utility of this organism for biopharmaceutical production. Despite its biotechnological importance, relatively few genetic tools or engineered strains have been generated for P. pastoris. To facilitate progress in these areas, we present the 9.43 Mbp genomic sequence of the GS115 strain of P. pastoris. We also provide manually curated annotation for its 5,313 protein-coding genes.
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Affiliation(s)
- Kristof De Schutter
- Unit for Molecular Glycobiology, Department for Molecular Biomedical Research, VIB, Ghent-Zwijnaarde, Belgium
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45
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Richard GF, Kerrest A, Dujon B. Comparative genomics and molecular dynamics of DNA repeats in eukaryotes. Microbiol Mol Biol Rev 2008; 72:686-727. [PMID: 19052325 PMCID: PMC2593564 DOI: 10.1128/mmbr.00011-08] [Citation(s) in RCA: 323] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Repeated elements can be widely abundant in eukaryotic genomes, composing more than 50% of the human genome, for example. It is possible to classify repeated sequences into two large families, "tandem repeats" and "dispersed repeats." Each of these two families can be itself divided into subfamilies. Dispersed repeats contain transposons, tRNA genes, and gene paralogues, whereas tandem repeats contain gene tandems, ribosomal DNA repeat arrays, and satellite DNA, itself subdivided into satellites, minisatellites, and microsatellites. Remarkably, the molecular mechanisms that create and propagate dispersed and tandem repeats are specific to each class and usually do not overlap. In the present review, we have chosen in the first section to describe the nature and distribution of dispersed and tandem repeats in eukaryotic genomes in the light of complete (or nearly complete) available genome sequences. In the second part, we focus on the molecular mechanisms responsible for the fast evolution of two specific classes of tandem repeats: minisatellites and microsatellites. Given that a growing number of human neurological disorders involve the expansion of a particular class of microsatellites, called trinucleotide repeats, a large part of the recent experimental work on microsatellites has focused on these particular repeats, and thus we also review the current knowledge in this area. Finally, we propose a unified definition for mini- and microsatellites that takes into account their biological properties and try to point out new directions that should be explored in a near future on our road to understanding the genetics of repeated sequences.
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Affiliation(s)
- Guy-Franck Richard
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, CNRS, URA2171, Université Pierre et Marie Curie, UFR927, 25 rue du Dr. Roux, F-75015, Paris, France.
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TFIIIC binding sites function as both heterochromatin barriers and chromatin insulators in Saccharomyces cerevisiae. EUKARYOTIC CELL 2008; 7:2078-86. [PMID: 18849469 DOI: 10.1128/ec.00128-08] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Chromosomal sites of RNA polymerase III (Pol III) transcription have been demonstrated to have "extratranscriptional" functions, as the assembled Pol III complex can act as chromatin boundaries or pause sites for replication forks, can alter nucleosome positioning or affect transcription of neighboring genes, and can play a role in sister chromatid cohesion. Several studies have demonstrated that assembled Pol III complexes block the propagation of heterochromatin-mediated gene repression. Here we show that in Saccharomyces cerevisiae tRNA genes (tDNAs) and even partially assembled Pol III complexes containing only the transcription factor TFIIIC can exhibit chromatin boundary functions both as heterochromatin barriers and as insulators to gene activation. Both the TRT2 tDNA and the ETC4 site which binds only the TFIIIC complex prevented an upstream activation sequence from activating the GAL promoters in our assay system, effectively acting as chromatin insulators. Additionally, when placed downstream from the heterochromatic HMR locus, ETC4 blocked the ectopic spread of Sir protein-mediated silencing, thus functioning as a barrier to repression. Finally, we show that TRT2 and the ETC6 site upstream of TFC6 in their natural contexts display potential insulator-like functions, and ETC6 may represent a novel case of a Pol III factor directly regulating a Pol II promoter. The results are discussed in the context of how the TFIIIC transcription factor complex may function to demarcate chromosomal domains in yeast and possibly in other eukaryotes.
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Pscheidt B, Glieder A. Yeast cell factories for fine chemical and API production. Microb Cell Fact 2008; 7:25. [PMID: 18684335 PMCID: PMC2628649 DOI: 10.1186/1475-2859-7-25] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Accepted: 08/07/2008] [Indexed: 12/25/2022] Open
Abstract
This review gives an overview of different yeast strains and enzyme classes involved in yeast whole-cell biotransformations. A focus was put on the synthesis of compounds for fine chemical and API (= active pharmaceutical ingredient) production employing single or only few-step enzymatic reactions. Accounting for recent success stories in metabolic engineering, the construction and use of synthetic pathways was also highlighted. Examples from academia and industry and advances in the field of designed yeast strain construction demonstrate the broad significance of yeast whole-cell applications. In addition to Saccharomyces cerevisiae, alternative yeast whole-cell biocatalysts are discussed such as Candida sp., Cryptococcus sp., Geotrichum sp., Issatchenkia sp., Kloeckera sp., Kluyveromyces sp., Pichia sp. (including Hansenula polymorpha = P. angusta), Rhodotorula sp., Rhodosporidium sp., alternative Saccharomyces sp., Schizosaccharomyces pombe, Torulopsis sp., Trichosporon sp., Trigonopsis variabilis, Yarrowia lipolytica and Zygosaccharomyces rouxii.
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Affiliation(s)
- Beate Pscheidt
- Research Centre Applied Biocatalysis GmbH, Petersgasse 14/3, 8010 Graz, Austria.
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Arimbasseri AG, Bhargava P. Chromatin structure and expression of a gene transcribed by RNA polymerase III are independent of H2A.Z deposition. Mol Cell Biol 2008; 28:2598-607. [PMID: 18268003 PMCID: PMC2293117 DOI: 10.1128/mcb.01953-07] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 12/04/2007] [Accepted: 02/04/2008] [Indexed: 01/09/2023] Open
Abstract
The genes transcribed by RNA polymerase III (Pol III) generally have intragenic promoter elements. One of them, the yeast U6 snRNA (SNR6) gene is activated in vitro by a positioned nucleosome between its intragenic box A and extragenic, downstream box B separated by approximately 200 bp. We demonstrate here that the in vivo chromatin structure of the gene region is characterized by the presence of an array of positioned nucleosomes, with only one of them in the 5' end of the gene having a regulatory role. A positioned nucleosome present between boxes A and B in vivo does not move when the gene is repressed due to nutritional deprivation. In contrast, the upstream nucleosome which covers the TATA box under repressed conditions is shifted approximately 50 bp further upstream by the ATP-dependent chromatin remodeler RSC upon activation. It is marked with the histone variant H2A.Z and H4K16 acetylation in active state. In the absence of H2A.Z, the chromatin structure of the gene does not change, suggesting that H2A.Z is not required for establishing the active chromatin structure. These results show that the chromatin structure directly participates in regulation of a Pol III-transcribed gene under different states of its activity in vivo.
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49
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Eukaryotic wobble uridine modifications promote a functionally redundant decoding system. Mol Cell Biol 2008; 28:3301-12. [PMID: 18332122 DOI: 10.1128/mcb.01542-07] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The translational decoding properties of tRNAs are modulated by naturally occurring modifications of their nucleosides. Uridines located at the wobble position (nucleoside 34 [U(34)]) in eukaryotic cytoplasmic tRNAs often harbor a 5-methoxycarbonylmethyl (mcm(5)) or a 5-carbamoylmethyl (ncm(5)) side chain and sometimes an additional 2-thio (s(2)) or 2'-O-methyl group. Although a variety of models explaining the role of these modifications have been put forth, their in vivo functions have not been defined. In this study, we utilized recently characterized modification-deficient Saccharomyces cerevisiae cells to test the wobble rules in vivo. We show that mcm(5) and ncm(5) side chains promote decoding of G-ending codons and that concurrent mcm(5) and s(2) groups improve reading of both A- and G-ending codons. Moreover, the observation that the mcm(5)U(34)- and some ncm(5)U(34)-containing tRNAs efficiently read G-ending codons challenges the notion that eukaryotes do not use U-G wobbling.
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50
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Plant EP, Nguyen P, Russ JR, Pittman YR, Nguyen T, Quesinberry JT, Kinzy TG, Dinman JD. Differentiating between near- and non-cognate codons in Saccharomyces cerevisiae. PLoS One 2007; 2:e517. [PMID: 17565370 PMCID: PMC1885216 DOI: 10.1371/journal.pone.0000517] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 05/18/2007] [Indexed: 11/18/2022] Open
Abstract
Background Decoding of mRNAs is performed by aminoacyl tRNAs (aa-tRNAs). This process is highly accurate, however, at low frequencies (10−3 – 10−4) the wrong aa-tRNA can be selected, leading to incorporation of aberrant amino acids. Although our understanding of what constitutes the correct or cognate aa-tRNA:mRNA interaction is well defined, a functional distinction between near-cognate or single mismatched, and unpaired or non-cognate interactions is lacking. Methodology/Principal Findings Misreading of several synonymous codon substitutions at the catalytic site of firefly luciferase was assayed in Saccharomyces cerevisiae. Analysis of the results in the context of current kinetic and biophysical models of aa-tRNA selection suggests that the defining feature of near-cognate aa-tRNAs is their potential to form mini-helical structures with A-site codons, enabling stimulation of GTPase activity of eukaryotic Elongation Factor 1A (eEF1A). Paromomycin specifically stimulated misreading of near-cognate but not of non-cognate aa-tRNAs, providing a functional probe to distinguish between these two classes. Deletion of the accessory elongation factor eEF1Bγ promoted increased misreading of near-cognate, but hyperaccurate reading of non-cognate codons, suggesting that this factor also has a role in tRNA discrimination. A mutant of eEF1Bα, the nucleotide exchange factor for eEF1A, promoted a general increase in fidelity, suggesting that the decreased rates of elongation may provide more time for discrimination between aa-tRNAs. A mutant form of ribosomal protein L5 promoted hyperaccurate decoding of both types of codons, even though it is topologically distant from the decoding center. Conclusions/Signficance It is important to distinguish between near-cognate and non-cognate mRNA:tRNA interactions, because such a definition may be important for informing therapeutic strategies for suppressing these two different categories of mutations underlying many human diseases. This study suggests that the defining feature of near-cognate aa-tRNAs is their potential to form mini-helical structures with A-site codons in the ribosomal decoding center. An aminoglycoside and a ribosomal factor can be used to distinguish between near-cognate and non-cognate interactions.
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Affiliation(s)
- Ewan P. Plant
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Phuc Nguyen
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Jonathan R. Russ
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Yvette R. Pittman
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey (UMDNJ) Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Thai Nguyen
- The Science and Technology Center at Eleanor Roosevelt High School, Greenbelt, Maryland, United States of America
| | | | - Terri Goss Kinzy
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey (UMDNJ) Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Jonathan D. Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail:
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