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U A, Viswam P, Kattupalli D, Eppurathu Vasudevan S. Elucidation of transfer RNAs as stress regulating agents and the experimental strategies to conceive the functional role of tRNA-derived fragments in plants. Crit Rev Biotechnol 2023; 43:275-292. [PMID: 35382663 DOI: 10.1080/07388551.2022.2026288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In plants, the transfer RNAs (tRNAs) exhibit their profound influence in orchestrating diverse physiological activities like cell growth, development, and response to several surrounding stimuli. The tRNAs, which were known to restrict their function solely in deciphering the codons, are now emerging as frontline defenders in stress biology. The plants that are constantly confronted with a huge panoply of stresses rely on tRNA-mediated stress regulation by altering the tRNA abundance, curbing the transport of tRNAs, fragmenting the mature tRNAs during stress. Among them, the studies on the generation of transfer RNA-derived fragments (tRFs) and their biological implication in stress response have attained huge interest. In plants, the tRFs hold stable expression patterns and regulate biological functions under diverse environmental conditions. In this review, we discuss the fate of plant tRNAs upon stress and thereafter how the tRFs are metamorphosed into sharp ammunition to wrestle with stress. We also address the various methods developed to date for uncovering the role of tRFs and their function in plants.
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Affiliation(s)
- Aswathi U
- Rajiv Gandhi Centre for Biotechnology, Transdisciplinary Biology Laboratory, Thiruvananthapuram, India
| | - Pooja Viswam
- Rajiv Gandhi Centre for Biotechnology, Transdisciplinary Biology Laboratory, Thiruvananthapuram, India
| | - Divya Kattupalli
- Rajiv Gandhi Centre for Biotechnology, Transdisciplinary Biology Laboratory, Thiruvananthapuram, India
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Rasskazov D, Chadaeva I, Sharypova E, Zolotareva K, Khandaev B, Ponomarenko P, Podkolodnyy N, Tverdokhleb N, Vishnevsky O, Bogomolov A, Podkolodnaya O, Savinkova L, Zemlyanskaya E, Golubyatnikov V, Kolchanov N, Ponomarenko M. Plant_SNP_TATA_Z-Tester: A Web Service That Unequivocally Estimates the Impact of Proximal Promoter Mutations on Plant Gene Expression. Int J Mol Sci 2022; 23:ijms23158684. [PMID: 35955817 PMCID: PMC9369029 DOI: 10.3390/ijms23158684] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
Synthetic targeted optimization of plant promoters is becoming a part of progress in mainstream postgenomic agriculture along with hybridization of cultivated plants with wild congeners, as well as marker-assisted breeding. Therefore, here, for the first time, we compiled all the experimental data—on mutational effects in plant proximal promoters on gene expression—that we could find in PubMed. Some of these datasets cast doubt on both the existence and the uniqueness of the sought solution, which could unequivocally estimate effects of proximal promoter mutation on gene expression when plants are grown under various environmental conditions during their development. This means that the inverse problem under study is ill-posed. Furthermore, we found experimental data on in vitro interchangeability of plant and human TATA-binding proteins allowing the application of Tikhonov’s regularization, making this problem well-posed. Within these frameworks, we created our Web service Plant_SNP_TATA_Z-tester and then determined the limits of its applicability using those data that cast doubt on both the existence and the uniqueness of the sought solution. We confirmed that the effects (of proximal promoter mutations on gene expression) predicted by Plant_SNP_TATA_Z-tester correlate statistically significantly with all the experimental data under study. Lastly, we exemplified an application of Plant_SNP_TATA_Z-tester to agriculturally valuable mutations in plant promoters.
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Affiliation(s)
| | - Irina Chadaeva
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | | | | | - Bato Khandaev
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | | | - Nikolay Podkolodnyy
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
- Institute of Computational Mathematics and Mathematical Geophysics, 630090 Novosibirsk, Russia
| | | | - Oleg Vishnevsky
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | - Anton Bogomolov
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | | | | | | | | | | | - Mikhail Ponomarenko
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
- Correspondence: ; Tel.: +7-(383)-363-4963 (ext. 1311)
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Fabres PJ, Anand L, Sai N, Pederson S, Zheng F, Stewart AA, Clements B, Lampugnani ER, Breen J, Gilliham M, Tricker P, Rodríguez López CM, David R. Tissue and regional expression patterns of dicistronic tRNA-mRNA transcripts in grapevine (Vitis vinifera) and their evolutionary co-appearance with vasculature in land plants. Hortic Res 2021; 8:137. [PMID: 34059643 PMCID: PMC8166872 DOI: 10.1038/s41438-021-00572-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 04/13/2021] [Accepted: 04/19/2021] [Indexed: 06/02/2023]
Abstract
Transfer RNAs (tRNA) are crucial adaptor molecules between messenger RNA (mRNA) and amino acids. Recent evidence in plants suggests that dicistronic tRNA-like structures also act as mobile signals for mRNA transcripts to move between distant tissues. Co-transcription is not a common feature in the plant nuclear genome and, in the few cases where polycistronic transcripts have been found, they include non-coding RNA species, such as small nucleolar RNAs and microRNAs. It is not known, however, the extent to which dicistronic transcripts of tRNA and mRNAs are expressed in field-grown plants, or the factors contributing to their expression. We analysed tRNA-mRNA dicistronic transcripts in the major horticultural crop grapevine (Vitis vinifera) using a novel pipeline developed to identify dicistronic transcripts from high-throughput RNA-sequencing data. We identified dicistronic tRNA-mRNA in leaf and berry samples from 22 commercial vineyards. Of the 124 tRNA genes that were expressed in both tissues, 18 tRNA were expressed forming part of 19 dicistronic tRNA-mRNAs. The presence and abundance of dicistronic molecules was tissue and geographic sub-region specific. In leaves, the expression patterns of dicistronic tRNA-mRNAs significantly correlated with tRNA expression, suggesting that their transcriptional regulation might be linked. We also found evidence of syntenic genomic arrangements of tRNAs and protein-coding genes between grapevine and Arabidopsis thaliana, and widespread prevalence of dicistronic tRNA-mRNA transcripts among vascular land plants but no evidence of these transcripts in non-vascular lineages. This suggests that the appearance of plant vasculature and tRNA-mRNA occurred concurrently during the evolution of land plants.
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Affiliation(s)
- Pastor Jullian Fabres
- School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA
| | - Lakshay Anand
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA
| | - Na Sai
- School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy Biology, Waite Research Institute & School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
| | - Stephen Pederson
- Bioinformatics Hub, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Fei Zheng
- School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy Biology, Waite Research Institute & School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
| | - Alexander A Stewart
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA
| | - Benjamin Clements
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA
| | - Edwin R Lampugnani
- School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - James Breen
- Bioinformatics Hub, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Matthew Gilliham
- School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy Biology, Waite Research Institute & School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
- ARC Industrial Transformation Training Centre in Innovative Wine Production, Waite Research Institute & School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
| | - Penny Tricker
- School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
| | - Carlos M Rodríguez López
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA.
| | - Rakesh David
- School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
- ARC Centre of Excellence in Plant Energy Biology, Waite Research Institute & School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
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Sanclemente MA, Ma F, Liu P, Della Porta A, Singh J, Wu S, Colquhoun T, Johnson T, Guan JC, Koch KE. Sugar modulation of anaerobic-response networks in maize root tips. Plant Physiol 2021; 185:295-317. [PMID: 33721892 PMCID: PMC8133576 DOI: 10.1093/plphys/kiaa029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/28/2020] [Indexed: 05/11/2023]
Abstract
Sugar supply is a key component of hypoxia tolerance and acclimation in plants. However, a striking gap remains in our understanding of mechanisms governing sugar impacts on low-oxygen responses. Here, we used a maize (Zea mays) root-tip system for precise control of sugar and oxygen levels. We compared responses to oxygen (21 and 0.2%) in the presence of abundant versus limited glucose supplies (2.0 and 0.2%). Low-oxygen reconfigured the transcriptome with glucose deprivation enhancing the speed and magnitude of gene induction for core anaerobic proteins (ANPs). Sugar supply also altered profiles of hypoxia-responsive genes carrying G4 motifs (sources of regulatory quadruplex structures), revealing a fast, sugar-independent class followed more slowly by feast-or-famine-regulated G4 genes. Metabolite analysis showed that endogenous sugar levels were maintained by exogenous glucose under aerobic conditions and demonstrated a prominent capacity for sucrose re-synthesis that was undetectable under hypoxia. Glucose abundance had distinctive impacts on co-expression networks associated with ANPs, altering network partners and aiding persistence of interacting networks under prolonged hypoxia. Among the ANP networks, two highly interconnected clusters of genes formed around Pyruvate decarboxylase 3 and Glyceraldehyde-3-phosphate dehydrogenase 4. Genes in these clusters shared a small set of cis-regulatory elements, two of which typified glucose induction. Collective results demonstrate specific, previously unrecognized roles of sugars in low-oxygen responses, extending from accelerated onset of initial adaptive phases by starvation stress to maintenance and modulation of co-expression relationships by carbohydrate availability.
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Affiliation(s)
- Maria-Angelica Sanclemente
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
- Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Utrecht 3584CH, The Netherlands
- Author for communication:
| | - Fangfang Ma
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, Shandong Agricultural University, Taian, Shandong, China
| | - Peng Liu
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA
| | - Adriana Della Porta
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
| | - Jugpreet Singh
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
| | - Shan Wu
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
| | - Thomas Colquhoun
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Environmental Horticulture, University of Florida, Gainesville, Florida, USA
| | - Timothy Johnson
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Environmental Horticulture, University of Florida, Gainesville, Florida, USA
| | - Jiahn-Chou Guan
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
| | - Karen E Koch
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
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Hummel G, Berr A, Graindorge S, Cognat V, Ubrig E, Pflieger D, Molinier J, Drouard L. Epigenetic silencing of clustered tRNA genes in Arabidopsis. Nucleic Acids Res 2020; 48:10297-10312. [PMID: 32941623 PMCID: PMC7544208 DOI: 10.1093/nar/gkaa766] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/21/2020] [Accepted: 09/03/2020] [Indexed: 12/12/2022] Open
Abstract
Beyond their key role in translation, cytosolic transfer RNAs (tRNAs) are involved in a wide range of other biological processes. Nuclear tRNA genes (tDNAs) are transcribed by the RNA polymerase III (RNAP III) and cis-elements, trans-factors as well as genomic features are known to influence their expression. In Arabidopsis, besides a predominant population of dispersed tDNAs spread along the 5 chromosomes, some clustered tDNAs have been identified. Here, we demonstrate that these tDNA clusters are transcriptionally silent and that pathways involved in the maintenance of DNA methylation play a predominant role in their repression. Moreover, we show that clustered tDNAs exhibit repressive chromatin features whilst their dispersed counterparts contain permissive euchromatic marks. This work demonstrates that both genomic and epigenomic contexts are key players in the regulation of tDNAs transcription. The conservation of most of these regulatory processes suggests that this pioneering work in Arabidopsis can provide new insights into the regulation of RNA Pol III transcription in other organisms, including vertebrates.
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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
| | - Alexandre Berr
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - Stéfanie Graindorge
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - Valérie Cognat
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - Elodie Ubrig
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - David Pflieger
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - Jean Molinier
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg, France
| | - 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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Oohashi F, Aga Y, Yukawa Y, Akama K. Novel in vivo system to monitor tRNA expression based on the recovery of GFP fluorescence and its application for the determination of plant tRNA expression. Gene 2019; 703:145-52. [PMID: 30940526 DOI: 10.1016/j.gene.2019.03.068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 03/01/2019] [Accepted: 03/29/2019] [Indexed: 11/23/2022]
Abstract
We developed a novel assay system to quantitatively detect amber codon suppression by tRNAs expressed in plant cells. The assay was based on recovery of the expression of the green fluorescent protein (GFP) as a reporter, in which a fourth Lys codon (AAG) was changed to a premature amber codon TAG, designated as GFP/amber. Plasmids carrying GFP/amber, suppressor tRNA, and red fluorescent protein (RFF) as an internal control, respectively, were introduced into onion epidermal cells to monitor cell numbers with GFP and RFP fluorescence. First, an amber suppressor tRNASer from tobacco (NtS2) to suppress a TAG codon in GFP mRNA was examined, leading to the recovery of GFP fluorescence. Second, we used two different tRNAs (i.e., AtY3II-am and AtY3II-amiG7), both of which are intron-containing amber suppressor tRNAsTyr, the former impaired precursor-tRNA splicing but the latter did not, as confirmed previously using two different approaches (Szeykowska-Kulinska and Beier, 1991; Akama and Beier, 2003). As expected, coexpression of GFP/amber with AtY3II-am gave no green fluorescence, but significant fluorescence was observed with AtY3II-amiG7. Then, we applied this system for the analysis of 5'-regulatory sequences of the tRNAGln gene family from Arabidopsis. A 5'-flanking sequence of each of the 17 tRNAGln genes was fused to a coding region of an amber suppressor tRNASer gene (NtS2/amber) and its 3'-flanking sequence. Chimeric tRNASer gene, GFP/amber, and RFP were coexpressed, and the GFP or RFP fluorescence intensity was determined in cells using laser-scanning microscopy. In parallel, 17 kinds of original Arabidopsis tRNAGln genes and their chimeric genes with NtS2/amber were all analyzed in cell-free nuclear extract (Yukawa et al., 1997). Comparison of in vitro and in vivo expression of these chimeric tRNA genes displayed generally similar results, accompanied by a wide range of variance in the expression of each gene. Nevertheless, the expression patterns of several genes were clearly the opposite of each other comparing between the two different system, demonstrating the importance of in vivo systems in the study on tRNA expression in plants.
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Soprano AS, Smetana JHC, Benedetti CE. Regulation of tRNA biogenesis in plants and its link to plant growth and response to pathogens. Biochim Biophys Acta Gene Regul Mech 2017; 1861:344-353. [PMID: 29222070 DOI: 10.1016/j.bbagrm.2017.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/29/2017] [Accepted: 12/03/2017] [Indexed: 12/23/2022]
Abstract
The field of tRNA biology, encompassing the functional and structural complexity of tRNAs, has fascinated scientists over the years and is continuously growing. Besides their fundamental role in protein translation, new evidence indicates that tRNA-derived molecules also regulate gene expression and protein synthesis in all domains of life. This review highlights some of the recent findings linking tRNA transcription and modification with plant cell growth and response to pathogens. In fact, mutations in proteins directly involved in tRNA synthesis and modification most often lead to pleiotropic effects on plant growth and immunity. As plants need to optimize and balance their energy and nutrient resources towards growth and defense, regulatory pathways that play a central role in integrating tRNA transcription and protein translation with cell growth control and organ development, such as the auxin-TOR signaling pathway, also influence the plant immune response against pathogens. As a consequence, distinct pathogens employ an array of effector molecules including tRNA fragments to target such regulatory pathways to exploit the plant's translational capacity, gain access to nutrients and evade defenses. An example includes the RNA polymerase III repressor MAF1, a conserved component of the TOR signaling pathway that controls ribosome biogenesis and tRNA synthesis required for plant growth and which is targeted by a pathogen effector molecule to promote disease. 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)
- Adriana Santos Soprano
- Brazilian Nacional Biosciences Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-100 Campinas, SP, Brazil
| | - Juliana Helena Costa Smetana
- Brazilian Nacional Biosciences Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-100 Campinas, SP, Brazil
| | - Celso Eduardo Benedetti
- Brazilian Nacional Biosciences Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-100 Campinas, SP, Brazil.
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Zhu F, Sun Y, Wang Y, Pan H, Wang F, Zhang X, Zhang Y, Liu J. Molecular Characterization of the Complete Genome of Three Basal-BR Isolates of Turnip mosaic virus Infecting Raphanus sativus in China. Int J Mol Sci 2016; 17:E888. [PMID: 27271614 PMCID: PMC4926422 DOI: 10.3390/ijms17060888] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/16/2016] [Accepted: 05/27/2016] [Indexed: 11/23/2022] Open
Abstract
Turnip mosaic virus (TuMV) infects crops of plant species in the family Brassicaceae worldwide. TuMV isolates were clustered to five lineages corresponding to basal-B, basal-BR, Asian-BR, world-B and OMs. Here, we determined the complete genome sequences of three TuMV basal-BR isolates infecting radish from Shandong and Jilin Provinces in China. Their genomes were all composed of 9833 nucleotides, excluding the 3'-terminal poly(A) tail. They contained two open reading frames (ORFs), with the large one encoding a polyprotein of 3164 amino acids and the small overlapping ORF encoding a PIPO protein of 61 amino acids, which contained the typically conserved motifs found in members of the genus Potyvirus. In pairwise comparison with 30 other TuMV genome sequences, these three isolates shared their highest identities with isolates from Eurasian countries (Germany, Italy, Turkey and China). Recombination analysis showed that the three isolates in this study had no "clear" recombination. The analyses of conserved amino acids changed between groups showed that the codons in the TuMV out group (OGp) and OMs group were the same at three codon sites (852, 1006, 1548), and the other TuMV groups (basal-B, basal-BR, Asian-BR, world-B) were different. This pattern suggests that the codon in the OMs progenitor did not change but that in the other TuMV groups the progenitor sequence did change at divergence. Genetic diversity analyses indicate that the PIPO gene was under the highest selection pressure and the selection pressure on P3N-PIPO and P3 was almost the same. It suggests that most of the selection pressure on P3 was probably imposed through P3N-PIPO.
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Affiliation(s)
- Fuxiang Zhu
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Ying Sun
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Yan Wang
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Hongyu Pan
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Fengting Wang
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Xianghui Zhang
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Yanhua Zhang
- College of Plant Sciences, Jilin University, Changchun 130062, China.
| | - Jinliang Liu
- College of Plant Sciences, Jilin University, Changchun 130062, China.
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Abstract
The 5S rDNA gene is a non-coding RNA that can be found in 2 copies (type I and type II) in bony and cartilaginous fish. Previous studies have pointed out that type II gene is a paralog derived from type I. We analyzed the molecular organization of 5S rDNA type II in elasmobranchs. Although the structure of the 5S rDNA is supposed to be highly conserved, our results show that the secondary structure in this group possesses some variability and is different than the consensus secondary structure. One of these differences in Selachii is an internal loop at nucleotides 7 and 112. These mutations observed in the transcribed region suggest an independent origin of the gene among Batoids and Selachii. All promoters were highly conserved with the exception of BoxA, possibly due to its affinity to polymerase III. This latter enzyme recognizes a dT4 sequence as stop signal, however in Rajiformes this signal was doubled in length to dT8. This could be an adaptation toward a higher efficiency in the termination process. Our results suggest that there is no TATA box in elasmobranchs in the NTS region. We also provide some evidence suggesting that the complexity of the microsatellites present in the NTS region play an important role in the 5S rRNA gene since it is significantly correlated with the length of the NTS.
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Affiliation(s)
- Sergio I. Castro
- Grupo de Estudios en Genética Ecología Molecular y Fisiología Animal, Universidad del Valle, Cali, Colombia
- Fundación Colombiana para la Investigación y Conservación de Tiburones y Rayas, SQUALUS. Cali, Colombia
| | - Jose S. Hleap
- Grupo de Estudios en Genética Ecología Molecular y Fisiología Animal, Universidad del Valle, Cali, Colombia
- Fundación Colombiana para la Investigación y Conservación de Tiburones y Rayas, SQUALUS. Cali, Colombia
- Canadian Institute for Advanced Research, Program in Evolutionary Biology, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
| | - Heiber Cárdenas
- Grupo de Estudios en Genética Ecología Molecular y Fisiología Animal, Universidad del Valle, Cali, Colombia
| | - Christian Blouin
- Canadian Institute for Advanced Research, Program in Evolutionary Biology, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
- Department of Computer Science, Dalhousie University, Halifax, Canada
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Rijal K, Maraia RJ, Arimbasseri AG. A methods review on use of nonsense suppression to study 3' end formation and other aspects of tRNA biogenesis. Gene 2014; 556:35-50. [PMID: 25447915 DOI: 10.1016/j.gene.2014.11.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 12/26/2022]
Abstract
Suppressor tRNAs bear anticodon mutations that allow them to decode premature stop codons in metabolic marker gene mRNAs, that can be used as in vivo reporters of functional tRNA biogenesis. Here, we review key components of a suppressor tRNA system specific to Schizosaccharomyces pombe and its adaptations for use to study specific steps in tRNA biogenesis. Eukaryotic tRNA biogenesis begins with transcription initiation by RNA polymerase (pol) III. The nascent pre-tRNAs must undergo folding, 5' and 3' processing to remove the leader and trailer, nuclear export, and splicing if applicable, while multiple complex chemical modifications occur throughout the process. We review evidence that precursor-tRNA processing begins with transcription termination at the oligo(T) terminator element, which forms a 3' oligo(U) tract on the nascent RNA, a sequence-specific binding site for the RNA chaperone, La protein. The processing pathway bifurcates depending on a poorly understood property of pol III termination that determines the 3' oligo(U) length and therefore the affinity for La. We thus review the pol III termination process and the factors involved including advances using gene-specific random mutagenesis by dNTP analogs that identify key residues important for transcription termination in certain pol III subunits. The review ends with a 'technical approaches' section that includes a parts lists of suppressor-tRNA alleles, strains and plasmids, and graphic examples of its diverse uses.
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Affiliation(s)
- Keshab Rijal
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Richard J Maraia
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Aneeshkumar G Arimbasseri
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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Yukawa Y, Akama K, Noguchi K, Komiya M, Sugiura M. The context of transcription start site regions is crucial for transcription of a plant tRNALys(UUU) gene group both in vitro and in vivo. Gene 2013; 512:286-93. [DOI: 10.1016/j.gene.2012.10.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/22/2012] [Accepted: 10/18/2012] [Indexed: 10/27/2022]
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13
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Dieci G, Bosio MC, Fermi B, Ferrari R. Transcription reinitiation by RNA polymerase III. Biochim Biophys Acta 2012; 1829:331-41. [PMID: 23128323 DOI: 10.1016/j.bbagrm.2012.10.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 01/11/2023]
Abstract
The retention of transcription proteins at an actively transcribed gene contributes to maintenance of the active transcriptional state and increases the rate of subsequent transcription cycles relative to the initial cycle. This process, called transcription reinitiation, generates the abundant RNAs in living cells. The persistence of stable preinitiation intermediates on activated genes representing at least a subset of basal transcription components has long been recognized as a shared feature of RNA polymerase (Pol) I, II and III-dependent transcription in eukaryotes. Studies of the Pol III transcription machinery and its target genes in eukaryotic genomes over the last fifteen years, has uncovered multiple details on transcription reinitiation. In addition to the basal transcription factors that recruit the polymerase, Pol III itself can be retained on the same gene through multiple transcription cycles by a facilitated recycling pathway. The molecular bases for facilitated recycling are progressively being revealed with advances in structural and functional studies. At the same time, progress in our understanding of Pol III transcriptional regulation in response to different environmental cues points to the specific mechanism of Pol III reinitiation as a key target of signaling pathway regulation of cell growth. This article is part of a Special Issue entitled: Transcription by Odd Pols.
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Affiliation(s)
- Giorgio Dieci
- Dipartimento di Bioscienze, Università degli Studi di Parma, Parco Area delle Scienze 23/A, 43124 Parma, Italy.
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14
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Orioli A, Pascali C, Pagano A, Teichmann M, Dieci G. RNA polymerase III transcription control elements: themes and variations. Gene 2012; 493:185-94. [PMID: 21712079 DOI: 10.1016/j.gene.2011.06.015] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 06/06/2011] [Accepted: 06/09/2011] [Indexed: 11/22/2022]
Abstract
Eukaryotic genomes are punctuated by a multitude of tiny genetic elements, that share the property of being recognized and transcribed by the RNA polymerase (Pol) III machinery to produce a variety of small, abundant non-protein-coding (nc) RNAs (tRNAs, 5S rRNA, U6 snRNA and many others). The highly selective, efficient and localized action of Pol III at its minute genomic targets is made possible by a handful of cis-acting regulatory elements, located within the transcribed region (where they are bound by the multisubunit assembly factor TFIIIC) and/or upstream of the transcription start site. Most of them participate directly or indirectly in the ultimate recruitment of TFIIIB, a key multiprotein initiation factor able to direct, once assembled, multiple transcription cycles by Pol III. But the peculiar efficiency and selectivity of Pol III transcription also depends on its ability to recognize very simple and precisely positioned termination signals. Studies in the last few years have significantly expanded the set of known Pol III-associated loci in genomes and, concomitantly, have revealed unexpected features of Pol III cis-regulatory elements in terms of variety, function, genomic location and potential contribution to transcriptome complexity. Here we review, in a historical perspective, well established and newly acquired knowledge about Pol III transcription control elements, with the aim of providing a useful reference for future studies of the Pol III system, which we anticipate will be numerous and intriguing for years to come.
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15
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Abstract
Although transfer RNA (tRNA) has a fundamental role in cell life, little is known about tRNA gene organization and expression on a genome-wide scale in eukaryotes, particularly plants. Here, we analyse the content and distribution of tRNA genes in five flowering plants and one green alga. The tRNA gene content is homogenous in plants, and is mostly correlated with genome size. The number of tRNA pseudogenes and organellar-like tRNA genes present in nuclear genomes varies greatly from one plant species to another. These pseudogenes or organellar-like genes appear to be generated or inserted randomly during evolution. Interestingly, we identified a new family of tRNA-related short interspersed nuclear elements (SINEs) in the Populus trichocarpa nuclear genome. In higher plants, intron-containing tRNA genes are rare, and correspond to genes coding for tRNA(Tyr) and tRNA(Mete) . By contrast, in green algae, more than half of the tRNA genes contain an intron. This suggests divergent means of intron acquisition and the splicing process between green algae and land plants. Numerous tRNAs are co-transcribed in Chlamydomonas, but they are mostly transcribed as a single unit in flowering plants. The only exceptions are tRNA(Gly) -snoRNA and tRNA(Mete) -snoRNA cotranscripts in dicots and monocots, respectively. The internal or external motifs required for efficient transcription of tRNA genes by RNA polymerase III are well conserved among angiosperms. A brief analysis of the mitochondrial and plastidial tRNA gene populations is also provided.
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Affiliation(s)
- Morgane Michaud
- Institut de Biologie Moléculaire des Plantes, UPR 2357-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg Cedex, France
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16
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Yukawa Y, Dieci G, Alzapiedi M, Hiraga A, Hirai K, Yamamoto YY, Sugiura M. A common sequence motif involved in selection of transcription start sites of Arabidopsis and budding yeast tRNA genes. Genomics 2010; 97:166-72. [PMID: 21147216 DOI: 10.1016/j.ygeno.2010.12.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 11/12/2010] [Accepted: 12/02/2010] [Indexed: 11/28/2022]
Abstract
The transcription start site (TSS) is useful to predict gene and to understand transcription initiation. Although vast data on mRNA TSSs are available, little is known about tRNA genes because of rapid processing. Using a tobacco in vitro transcription system under conditions of impaired 5' end processing, TSSs were determined for 64 Arabidopsis tRNA genes. This analysis revealed multiple TSSs distributed in a region from 10 to 2bp upstream of the mature tRNA coding sequence (-10 to -2). We also analyzed 31 Saccharomyces cerevisiae tRNA genes that showed a smaller number but a broader distribution (-13 to -1) of TSSs. In both cases, transcription was initiated preferentially at adenosine, and a common 'TCAACA' sequence was found spanning the TSSs. In plant, this motif caused multiple TSSs to converge at one site and enhanced transcription. The TATA-like sequence upstream of Arabidopsis tRNA genes also contributed to TSS selection.
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Affiliation(s)
- Yasushi Yukawa
- Graduate School of Natural Sciences, Nagoya City University, 467-8501 Nagoya, Japan.
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17
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Zhang G, Lukoszek R, Mueller-Roeber B, Ignatova Z. Different sequence signatures in the upstream regions of plant and animal tRNA genes shape distinct modes of regulation. Nucleic Acids Res 2010; 39:3331-9. [PMID: 21138970 PMCID: PMC3082873 DOI: 10.1093/nar/gkq1257] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In eukaryotes, the transcription of tRNA genes is initiated by the concerted action of transcription factors IIIC (TFIIIC) and IIIB (TFIIIB) which direct the recruitment of polymerase III. While TFIIIC recognizes highly conserved, intragenic promoter elements, TFIIIB binds to the non-coding 5'-upstream regions of the tRNA genes. Using a systematic bioinformatic analysis of 11 multicellular eukaryotic genomes we identified a highly conserved TATA motif followed by a CAA-motif in the tRNA upstream regions of all plant genomes. Strikingly, the 5'-flanking tRNA regions of the animal genomes are highly heterogeneous and lack a common conserved sequence signature. Interestingly, in the animal genomes the tRNA species that read the same codon share conserved motifs in their upstream regions. Deep-sequencing analysis of 16 human tissues revealed multiple splicing variants of two of the TFIIIB subunits, Bdp1 and Brf1, with tissue-specific expression patterns. These multiple forms most likely modulate the TFIIIB-DNA interactions and explain the lack of a uniform signature motif in the tRNA upstream regions of animal genomes. The anticodon-dependent 5'-flanking motifs provide a possible mechanism for independent regulation of the tRNA transcription in various human tissues.
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Affiliation(s)
- Gong Zhang
- Department of Biochemistry, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str 24-25, 14476 Potsdam, Potsdam, Germany
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18
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Fulnecek J, Kovarik A. Low abundant spacer 5S rRNA transcripts are frequently polyadenylated in Nicotiana. Mol Genet Genomics 2007; 278:565-73. [PMID: 17671796 DOI: 10.1007/s00438-007-0273-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 06/22/2007] [Accepted: 06/27/2007] [Indexed: 10/23/2022]
Abstract
In plants, 5S rRNA genes (5S rDNA) encoding 120-nt structural RNA molecules of ribosomes are organized in tandem arrays comprising thousands of units. Failure to correctly terminate transcription would generate longer inaccurately processed transcripts interfering with ribosome biogenesis. Hence multiple termination signals occur immediately after the 5S rRNA coding sequence. To obtain information about the efficiency of termination of 5S rDNA transcription in plants we analyzed 5S rRNA pools in three Nicotiana species, N. sylvestris, N. tomentosiformis and N. tabacum. In addition to highly abundant 120-nt 5S rRNA transcripts, we also detected RNA species composed of a genic region and variable lengths of intergenic sequences. These genic-intergenic RNA molecules occur at a frequency severalfold lower than the mature 120-nt transcripts, and are posttranscriptionally modified by polyadenylation at their 3' end in contrast to 120-nt transcripts. An absence of 5S small RNAs (smRNA) argue against a dominant role for the smRNA biosynthesis pathway in the degradation of aberrant 5S rRNA in Nicotiana. This work is the first description of polyadenylated 5S rRNA species in higher eukaryotes originating from a read-through transcription into the intergenic spacer. We propose that polyadenylation may function in a "quality control" pathway ensuring that only correctly processed molecules enter the ribosome biogenesis.
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Affiliation(s)
- Jaroslav Fulnecek
- Institute of Biophysics, Academy of Sciences of the Czech Republic v.v.i, Kralovopolska 135, 612 65, Brno, Czech Republic.
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19
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Douet J, Tourmente S. Transcription of the 5S rRNA heterochromatic genes is epigenetically controlled in Arabidopsis thaliana and Xenopus laevis. Heredity (Edinb) 2007; 99:5-13. [PMID: 17487217 DOI: 10.1038/sj.hdy.6800964] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
5S ribosomal DNA is a highly conserved tandemly repeated multigenic family. As suggested for a long time, we have shown that only a fraction of the 5S rRNA genes are expressed in Arabidopsis thaliana. In Xenopus laevis, there is a developmental control of the expression of the 5S rRNA genes with only one of the two 5S rDNA families expressed during oogenesis. For both Arabidopsis and Xenopus, the strongest transcription of 5S rRNA, respectively in the seed and during oogenesis is correlated with heterogeneity in the transcribed 5S rRNAs. Epigenetic mechanisms such as modification of the chromatin structure are involved in the transcriptional regulation of the 5S rRNA genes in both organisms. In Arabidopsis, two silencing pathways, methylation-dependent (RNAi) and methylation-independent (MOM pathway), are involved in the silencing of a 5S rDNA fraction.
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Affiliation(s)
- J Douet
- Unité Mixte de Recherche CNRS 6547 BIOMOVE, Université Blaise Pascal, Aubière Cedex, France
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20
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Yukawa Y, Mizutani T, Akama K, Sugiura M. A survey of expressed tRNA genes in the chromosome I of Arabidopsis using an RNA polymerase III-dependent in vitro transcription system. Gene 2007; 392:7-13. [PMID: 17157999 DOI: 10.1016/j.gene.2006.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 09/23/2006] [Accepted: 10/11/2006] [Indexed: 11/24/2022]
Abstract
Eukaryotic tRNA genes are transcribed by RNA polymerase III. These tRNA genes are generally predicted using computer programs, and 620 tRNA genes in the Arabidopsis thaliana genome are currently annotated. However, no effort has been made to assay whether these predicted tRNA genes are all expressed, because it has been difficult to assay by routine in vivo methods. We report here a large-scale tRNA expression assay of predicted Arabidopsis tRNA genes using an RNA polymerase III-dependent in vitro transcription system developed by our group. DNA fragments including an annotated tRNA gene each were amplified by PCR and the resulting linear DNA was subjected to in vitro transcription. The addition of poly(dA-dT).poly(dA-dT) enhanced activity significantly and reduced background. The 124 predicted tRNA genes present in the Arabidopsis chromosome I were examined, and transcription activity and transcript stability from individual genes were determined. These results indicated that eight annotated genes are not expressed. Based on previous reports on pseudo-tRNA genes (e.g., Beier and Beier, Mol. Gen. Genet. 1992; 233: 201-208) and the present results, we estimated that 16% or more of the annotated tRNA genes in the chromosome I are not functional.
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Affiliation(s)
- Yasushi Yukawa
- Graduate School of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan
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21
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Guffanti E, Ferrari R, Preti M, Forloni M, Harismendy O, Lefebvre O, Dieci G. A Minimal Promoter for TFIIIC-dependent in Vitro Transcription of snoRNA and tRNA Genes by RNA Polymerase III. J Biol Chem 2006; 281:23945-57. [PMID: 16787917 DOI: 10.1074/jbc.m513814200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Saccharomyces cerevisiae SNR52 gene is unique among the snoRNA coding genes in being transcribed by RNA polymerase III. The primary transcript of SNR52 is a 250-nucleotide precursor RNA from which a long leader sequence is cleaved to generate the mature snR52 RNA. We found that the box A and box B sequence elements in the leader region are both required for the in vivo accumulation of the snoRNA. As expected box B, but not box A, was absolutely required for stable TFIIIC, yet in vitro. Surprisingly, however, the box B was found to be largely dispensable for in vitro transcription of SNR52, whereas the box A-mutated template effectively recruited TFIIIB; yet it was transcriptionally inactive. Even in the complete absence of box B and both upstream TATA-like and T-rich elements, the box A still directed efficient, TFIIIC-dependent transcription. Box B-independent transcription was also observed for two members of the tRNA(Asn)(GTT) gene family, but not for two tRNA(Pro)(AGG) gene copies. Fully recombinant TFIIIC supported box B-independent transcription of both SNR52 and tRNA(Asn) genes, but only in the presence of TFIIIB reconstituted with a crude B'' fraction. Non-TFIIIB component(s) in this fraction were also required for transcription of wild-type SNR52. Transcription of the box B-less tRNA(Asn) genes was strongly influenced by their 5'-flanking regions, and it was stimulated by TBP and Brf1 proteins synergistically. The box A can thus be viewed as a core TFIIIC-interacting element that, assisted by upstream TFIIIB-DNA contacts, is sufficient to promote class III gene transcription.
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Affiliation(s)
- Elisa Guffanti
- Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Parma, 43100 Parma, Italy
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22
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Wu XR, Chen Z, Shende A, Dooner HK, Folk WR. Visualizing bz1 missense suppression in Zea mays: an assay for monocot tRNA expression and utilization. Plant Mol Biol 2006; 61:795-8. [PMID: 16897493 DOI: 10.1007/s11103-006-0050-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Accepted: 03/20/2006] [Indexed: 05/11/2023]
Abstract
Bombardment of a highly expressed dicot tRNA(ala)(GAC) gene into Zea mays bz-E2 or bz-E5 coleoptiles causes suppression of an Ala(458 )-->Val missense mutation, visualized by the development of anthocyanin pigment. Missense suppression is blocked by mutation of tRNA(ala)(GAC) at a site that prevents aminoacylation by the dicot alanyl-tRNA synthetase, indicating that features identified for expression and utilization of dicot tRNAs also function in monocots. This assay of the expression and utilization of tRNA(ala)(GAC) also can be used to study a variety of tRNAs and their genes, most of which can be relatively easily altered to be charged by alanyl tRNA synthetase.
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Affiliation(s)
- Xing Rong Wu
- Department of Biochemistry, University of Missouri-Columbia, 117 Schweitzer Hall, Columbia, MO, 65211, USA
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23
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Dieci G, Yukawa Y, Alzapiedi M, Guffanti E, Ferrari R, Sugiura M, Ottonello S. Distinct modes of TATA box utilization by the RNA polymerase III transcription machineries from budding yeast and higher plants. Gene 2006; 379:12-25. [PMID: 16839711 DOI: 10.1016/j.gene.2006.03.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 03/23/2006] [Accepted: 03/24/2006] [Indexed: 10/24/2022]
Abstract
The TATA box is a key upstream control element for basal tRNA gene transcription by RNA polymerase III in some eukaryotes, such as the fission yeast (Schizosaccharomyces pombe) and higher plants, but not in others such as the budding yeast (Saccharomyces cerevisiae). To gain information on this differential TATA box requirement, we examined side-by-side the in vitro transcription properties of TATA-containing and TATA-mutated plant and S. cerevisiae tDNAs in homologous in vitro transcription systems from both organisms and in a hybrid system in which yeast TBP was replaced by its plant homologue. The data support the general conclusion that specific features of the plant transcription machinery, rather than upstream region architecture per se, are responsible for the much stronger TATA box dependence of the plant system. In both systems, however, a strong influence of the TATA box on transcription start site selection was observed. This was particularly striking in the case of plant tDNAs, where TATA-rich upstream regions were found to favour the use of alternative initiation sites. Replacement of yeast TBP with its plant counterpart did not confer any general TATA box responsiveness to the yeast transcription machinery. Interactions involving components other than TBP are thus responsible for the strong TATA box requirement of plant tDNA transcription.
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Affiliation(s)
- Giorgio Dieci
- Department of Biochemistry and Molecular Biology, University of Parma, Parco Area delle Scienze 23A, 43100 Parma, Italy.
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Yukawa Y, Felis M, Englert M, Stojanov M, Matousek J, Beier H, Sugiura M. Plant 7SL RNA genes belong to type 4 of RNA polymerase III- dependent genes that are composed of mixed promoters. Plant J 2005; 43:97-106. [PMID: 15960619 DOI: 10.1111/j.1365-313x.2005.02430.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The genes transcribed by RNA polymerase III (pol III) display a great diversity in terms of promoter structure and are placed in four groups accordingly. Type 3 subset of pol III genes has promoter elements which reside entirely upstream of the coding region of the gene whereas type 4 consists of genes with mixed promoters that enclose intra- and extragenic regulatory sequences. Plant 7SL RNA genes have been previously classified as type 3 of pol III genes requiring an upstream sequence element and a canonical TATA box for transcriptional activity in transfected plant protoplasts. We have identified two novel functional control regions within the coding region of an Arabidopsis 7SL RNA gene (At7SL-1) that resemble tRNA gene-specific A and B boxes with respect to sequence and position. Single and multiple nucleotide substitutions in either of these regions resulted in a pronounced reduction of transcription activity in tobacco nuclear extract that was not caused by a decreased stability as shown by decay kinetics of wild type and mutant RNA transcripts. These findings suggest that plant 7SL RNA genes should be actually placed in type 4 of pol III-transcribed genes. As a consequence of substantially different upstream promoters utilized by plant and human pol III, in vitro transcription of 7SL RNA genes in heterologous systems is severely impaired. A chimeric human 7SL RNA gene that contains the 5' flanking region up to position -300 of At7SL-1 is yet transcribed with a reduced efficiency in tobacco extract when compared with the plant wild-type gene, supporting the notion that internal regulatory elements contribute to full activity.
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Affiliation(s)
- Yasushi Yukawa
- Graduate School of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan
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25
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Giuliodori S, Percudani R, Braglia P, Ferrari R, Guffanti E, Ottonello S, Dieci G. A composite upstream sequence motif potentiates tRNA gene transcription in yeast. J Mol Biol 2003; 333:1-20. [PMID: 14516739 DOI: 10.1016/j.jmb.2003.08.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Transcription of eukaryotic tRNA genes relies on the TFIIIC-dependent recruitment of TFIIIB on a approximately 50 bp region upstream of the transcription start site (TSS). TFIIIC specifically interacts with highly conserved, intragenic promoter elements, while the contacts between TFIIIB and the upstream DNA have long been considered as largely non-specific. Through a computer search procedure designed to detect shared, yet degenerate sequence features, we have identified a conserved sequence pattern upstream of Saccharomyces cerevisiae tDNAs. This pattern consists of four regions in which particular sequences are over-represented. The most downstream of these regions surrounds the TSS, while the other three districts of sequence conservation (appearing as a centrally located TATA-like sequence flanked by T-rich elements on both sides) are located across the DNA region known to interact with TFIIIB. Upstream regions whose sequence conforms to this pattern were found to potentiate tRNA gene transcription, both in vitro and in vivo, by enhancing TFIIIB binding. A conserved pattern of DNA bendability was also revealed, with peaks of bending propensity centered on the TATA-like and the TSS regions. Sequence analysis of other eukaryotic genomes further revealed the widespread occurrence of conserved sequence patterns upstream of tDNAs, with striking lineage-specific differences in the number and sequence of conserved motifs. Our data strongly support the notion that tRNA gene transcription in eukaryotes is modulated by composite TFIIIB binding sites that may confer responsiveness to variation in TFIIIB activity and/or concentration.
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Affiliation(s)
- Silvia Giuliodori
- Dipartimento di Biochimica e Biologia Molecolare, Università di Parma, Parco Area delle Scienze 23/A, 43100 Parma, Italy
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26
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Cloix C, Yukawa Y, Tutois S, Sugiura M, Tourmente S. In vitro analysis of the sequences required for transcription of the Arabidopsis thaliana 5S rRNA genes. Plant J 2003; 35:251-261. [PMID: 12848829 DOI: 10.1046/j.1365-313x.2003.01793.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In vivo, we have already shown that only two of the 5S rDNA array blocks of the Arabidopsis thaliana genome produce the mature 5S rRNAs. Deletions and point mutations were introduced in an Arabidopsis 5S rDNA-transcribed region and its 5'- and 3'-flanks in order to analyse their effects on transcription activity. In vitro transcription revealed different transcription control regions. One control region essential for transcription initiation was identified in the 5'-flanking sequence. The major sequence determinants were a TATA-like motif (-28 to -23), a GC dinucleotide (-12 to -11), a 3-bp AT-rich region (-4 to -2) and a C residue at -1. They are important for both accurate transcription initiation and transcription efficiency. Transcription level was regulated by polymerase III (Pol III) re-initiation rate as in tRNA genes in which TATA-like motif is involved. Active 5S rDNA transcription additionally required an intragenic promoter composed of an A-box, an Intermediate Element (IE) and a C-box. Double-stranded oligonucleotides corresponding to different fragments of the transcribed region, used as competitors, revealed the main importance of internal promoter elements. A stretch of four T is sufficient for transcription termination. Transcription of Arabidopsis 5S rDNA requires 30 bp of 5'-flanking region, a promoter internal to the transcribed region, and a stretch of T for transcription termination.
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Affiliation(s)
- Catherine Cloix
- U. M. R. 6547 BIOMOVE, Université Blaise Pascal, 24 Avenue des Landais, 63177 Aubière Cedex, France
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27
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Hasegawa K, Yukawa Y, Obokata J, Sugiura M. A tRNA(Leu)-like sequence located immediately upstream of an Arabidopsis clock-regulated gene is transcriptionally active: efficient transcription by an RNA polymerase III-dependent in vitro transcription system. Gene 2003; 307:133-9. [PMID: 12706895 DOI: 10.1016/s0378-1119(03)00452-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A tRNA(Leu)-like sequence is located within a probable enhancer region of the RNA polymerase II-dependent gene encoding an RNA-binding protein, Atgrp7, in Arabidopsis (Mol. Gen. Genet. 261 (1999) 811). To examine whether this sequence is transcribed, we used our in vitro transcription system from tobacco cell nuclei. In vitro assays demonstrated that this tRNA-like sequence is transcribed by RNA polymerase III and its transcript is processed into tRNA-size molecules. Transcription starts at the CAA motif, a transcription initiation site for many plant tRNA genes. Mutation analyses indicated that transcription of this sequence depends on promoter elements typical for plant tRNA genes. We therefore concluded that this is a transcriptionally active tRNA(Leu)(AAG) gene. Mutation of a basic promoter element of the tRNA gene exerted no influence on the transcription of the downstream protein-coding gene, suggesting that no apparent interference occurs between the two adjacent genes.
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Affiliation(s)
- Keiko Hasegawa
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
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Hasegawa K, Yukawa Y, Sugiura M. In vitro analysis of transcription initiation and termination from the Lhcb1 gene family in Nicotiana sylvestris: detection of transcription termination sites. Plant J 2003; 33:1063-72. [PMID: 12631330 DOI: 10.1046/j.1365-313x.2003.01693.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Genes encoding chlorophyll a/b-binding proteins of photosystem II (Lhcb) constitute a multigene family. Nine Lhcb1 genes have previously been isolated from the tobacco species, Nicotiana sylvestris, and the transcription initiation sites in vivo have been mapped. Reaction conditions from a previously developed in vitro transcription system from tobacco cultured cells were optimized for the Lhcb1 genes. Transcription initiation sites in vitro predominantly coincided with those found in vivo and were typically cytidines, a system unique to N. sylvestris Lhcb1 genes. CTC*A (C* for initiation site) was a consensus motif for the initiation region in vitro, as reported in vivo. Mutation analysis defined functionally that the TATA box is essential for transcription initiation and that the CTCA motif is a determinant of transcription initiation sites but not transcript levels. Polyadenylation sites were determined from in vivo transcripts, located 12-21 nt downstream from likely poly(A) signals. Four major 3'-ends of in vitro transcripts from Lhcb1*6 were detected, 40-300 nt downstream of the poly(A) site, suggestive of multiple, discrete transcription termination sites. These 3'-ends are mapped in or nearby T-rich sequences.
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Affiliation(s)
- Keiko Hasegawa
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
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Kruszka K, Barneche F, Guyot R, Ailhas J, Meneau I, Schiffer S, Marchfelder A, Echeverría M. Plant dicistronic tRNA-snoRNA genes: a new mode of expression of the small nucleolar RNAs processed by RNase Z. EMBO J 2003; 22:621-32. [PMID: 12554662 PMCID: PMC140725 DOI: 10.1093/emboj/cdg040] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Small nucleolar RNAs (snoRNAs) guiding modifications of ribosomal RNAs and other RNAs display diverse modes of gene organization and expression depending on the eukaryotic system: in animals most are intron encoded, in yeast many are monocistronic genes and in plants most are polycistronic (independent or intronic) genes. Here we report an unprecedented organization: plant dicistronic tRNA-snoRNA genes. In Arabidopsis thaliana we identified a gene family encoding 12 novel box C/D snoRNAs (snoR43) located just downstream from tRNA(Gly) genes. We confirmed that they are transcribed, probably from the tRNA gene promoter, producing dicistronic tRNA(Gly)-snoR43 precursors. Using transgenic lines expressing a tagged tRNA-snoR43.1 gene we show that the dicistronic precursor is accurately processed to both snoR43.1 and tRNA(Gly). In addition, we show that a recombinant RNase Z, the plant tRNA 3' processing enzyme, efficiently cleaves the dicistronic precursor in vitro releasing the snoR43.1 from the tRNA(Gly). Finally, we describe a similar case in rice implicating a tRNA(Met-e) expressed in fusion with a novel C/D snoRNA, showing that this mode of snoRNA expression is found in distant plant species.
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Affiliation(s)
| | - Fredy Barneche
- Laboratoire Génome et Développement des Plantes, UMR CNRS 5096, Université de Perpignan, 66860 Perpignan cedex, France,
Molecular Biology Department, University of Geneva-Sciences II, 30 Quai Ernest Ansermet, 1211-Geneva, Institut of Plant Biology, University of Zurich, Zollikerstrasse 19, 8008-Zurich, Switzerland and Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany Corresponding author e-mail:
K.Kruszka, F.Barneche and R.Guyot contributed equally to this work
| | - Romain Guyot
- Laboratoire Génome et Développement des Plantes, UMR CNRS 5096, Université de Perpignan, 66860 Perpignan cedex, France,
Molecular Biology Department, University of Geneva-Sciences II, 30 Quai Ernest Ansermet, 1211-Geneva, Institut of Plant Biology, University of Zurich, Zollikerstrasse 19, 8008-Zurich, Switzerland and Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany Corresponding author e-mail:
K.Kruszka, F.Barneche and R.Guyot contributed equally to this work
| | | | | | - Steffen Schiffer
- Laboratoire Génome et Développement des Plantes, UMR CNRS 5096, Université de Perpignan, 66860 Perpignan cedex, France,
Molecular Biology Department, University of Geneva-Sciences II, 30 Quai Ernest Ansermet, 1211-Geneva, Institut of Plant Biology, University of Zurich, Zollikerstrasse 19, 8008-Zurich, Switzerland and Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany Corresponding author e-mail:
K.Kruszka, F.Barneche and R.Guyot contributed equally to this work
| | - Anita Marchfelder
- Laboratoire Génome et Développement des Plantes, UMR CNRS 5096, Université de Perpignan, 66860 Perpignan cedex, France,
Molecular Biology Department, University of Geneva-Sciences II, 30 Quai Ernest Ansermet, 1211-Geneva, Institut of Plant Biology, University of Zurich, Zollikerstrasse 19, 8008-Zurich, Switzerland and Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany Corresponding author e-mail:
K.Kruszka, F.Barneche and R.Guyot contributed equally to this work
| | - Manuel Echeverría
- Laboratoire Génome et Développement des Plantes, UMR CNRS 5096, Université de Perpignan, 66860 Perpignan cedex, France,
Molecular Biology Department, University of Geneva-Sciences II, 30 Quai Ernest Ansermet, 1211-Geneva, Institut of Plant Biology, University of Zurich, Zollikerstrasse 19, 8008-Zurich, Switzerland and Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany Corresponding author e-mail:
K.Kruszka, F.Barneche and R.Guyot contributed equally to this work
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Affiliation(s)
- Laura Schramm
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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Abstract
Nine Lhcb1 genes encoding the light-harvesting chlorophyll a/b-binding proteins of photosystem II were isolated and characterized from Nicotiana sylvestris. Their nucleotide sequences are highly similar. Lhcb1 transcripts are accumulated in leaves and stems but not in roots and non-green cultured cells. RNase protection assay revealed that no transcripts were detected from the gene, Lhcb1*2, in Nicotiana tabacum. This finding raises the possibility that the amphidiploid tobacco cultivar (N. tabacum) lost one gene from the female progenitor (N. sylvestris) during evolution. Transcriptional initiation sites were mapped and found to be mostly cytidine residues, which is unique to the N. sylvestris Lhcb1 genes. Four of the nine genes have single start sites and the remaining genes possess multiple initiation sites. The TATA-like sequences of nine Lhcb1 genes can be classified into two groups; one that possesses a TTTATA sequence and the other that has a sequence diverged from it. The genes with single initiation sites belong to the first group. A consensus motif for the initiation region is CTC*A (C* for initiation site), which differs from those of other plant genes or mammalian genes.
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Affiliation(s)
- Keiko Hasegawa
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
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Dieci G, Giuliodori S, Catellani M, Percudani R, Ottonello S. Intragenic promoter adaptation and facilitated RNA polymerase III recycling in the transcription of SCR1, the 7SL RNA gene of Saccharomyces cerevisiae. J Biol Chem 2002; 277:6903-14. [PMID: 11741971 DOI: 10.1074/jbc.m105036200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The SCR1 gene, coding for the 7SL RNA of the signal recognition particle, is the last known class III gene of Saccharomyces cerevisiae that remains to be characterized with respect to its mode of transcription and promoter organization. We show here that SCR1 represents a unique case of a non-tRNA class III gene in which intragenic promoter elements (the TFIIIC-binding A- and B-blocks), corresponding to the D and TpsiC arms of mature tRNAs, have been adapted to a structurally different small RNA without losing their transcriptional function. In fact, despite the presence of an upstream canonical TATA box, SCR1 transcription strictly depends on the presence of functional, albeit quite unusual, A- and B-blocks and requires all the basal components of the RNA polymerase III transcription apparatus, including TFIIIC. Accordingly, TFIIIC was found to protect from DNase I digestion an 80-bp region comprising the A- and B-blocks. B-block inactivation completely compromised TFIIIC binding and transcription capacity in vitro and in vivo. An inactivating mutation in the A-block selectively affected TFIIIC binding to this promoter element but resulted in much more dramatic impairment of in vivo than in vitro transcription. Transcriptional competition and nucleosome disruption experiments showed that this stronger in vivo defect is due to a reduced ability of A-block-mutated SCR1 to compete with other genes for TFIIIC binding and to counteract the assembly of repressive chromatin structures through TFIIIC recruitment. A kinetic analysis further revealed that facilitated RNA polymerase III recycling, far from being restricted to typical small sized class III templates, also takes place on the 522-bp-long SCR1 gene, the longest known class III transcriptional unit.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Binding Sites
- Binding, Competitive
- Chromatin/chemistry
- Chromatin/metabolism
- Cloning, Molecular
- Deoxyribonuclease I/metabolism
- Kinetics
- Models, Genetic
- Molecular Sequence Data
- Mutagenesis
- Mutagenesis, Site-Directed
- Mutation
- Nucleosomes/metabolism
- Promoter Regions, Genetic
- Protein Binding
- RNA/metabolism
- RNA Polymerase III/genetics
- RNA, Small Cytoplasmic/metabolism
- RNA, Transfer/metabolism
- Receptors, Complement/genetics
- Receptors, Complement/metabolism
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae/metabolism
- Signal Recognition Particle/metabolism
- Transcription Factors, TFIII/genetics
- Transcription Factors, TFIII/metabolism
- Transcription, Genetic
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Affiliation(s)
- Giorgio Dieci
- Dipartimento di Biochimica e Biologia Molecolare, Università di Parma, I-43100 Parma, Italy.
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Cloix C, Tutois S, Yukawa Y, Mathieu O, Cuvillier C, Espagnol MC, Picard G, Tourmente S. Analysis of the 5S RNA pool in Arabidopsis thaliana: RNAs are heterogeneous and only two of the genomic 5S loci produce mature 5S RNA. Genome Res 2002; 12:132-44. [PMID: 11779838 PMCID: PMC155267 DOI: 10.1101/gr.181301] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2001] [Accepted: 10/26/2001] [Indexed: 11/25/2022]
Abstract
One major 5S RNA, 120 bases long, was revealed by an analysis of mature 5S RNA from tissues, developmental stages, and polysomes in Arabidopsis thaliana. Minor 5S RNA were also found, varying from the major one by one or two base substitutions; 5S rDNA units from each 5S array of the Arabidopsis genome were isolated by PCR using CIC yeast artificial chromosomes (YACs) mapped on the different loci. By using a comparison of the 5S DNA and RNA sequences, we could show that both major and minor 5S transcripts come from only two of the genomic 5S loci: chromosome 4 and chromosome 5 major block. Other 5S loci are either not transcribed or produce rapidly degraded 5S transcripts. Analysis of the 5'- and 3'-DNA flanking sequence has permitted the definition of specific signatures for each 5S rDNA array.
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Affiliation(s)
- Catherine Cloix
- U.M.R. 6547 BIOMOVE, Université Blaise Pascal, 24 Avenue des Landais, 63177 Aubière Cedex, France
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Yukawa Y, Fan H, Akama K, Beier H, Gross HJ, Sugiura M. A tobacco nuclear extract supporting transcription, processing, splicing and modification of plant intron-containing tRNA precursors. Plant J 2001; 28:583-94. [PMID: 11849597 DOI: 10.1046/j.1365-313x.2001.01172.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Nuclear tRNA genes are transcribed by RNA polymerase III (Pol III) and pre-tRNAs are processed into mature tRNAs via complex processes in the nucleus. We have developed an in vitro Pol III-dependent transcription system derived from tobacco cultured cells, which supports efficiently not only transcription of a variety of plant tRNA genes but also 5'-and 3'-end processing, nucleotide modification and splicing of intron-containing pre-tRNAs. The structures of in vitro transcripts have been confirmed by primer extension analysis and by RNase T1 fingerprinting. The optimal Mg2+ concentration differed for each step so that each reaction can be controlled by adjusting the Mg2+ concentration. At 1 mm Mg2+, only transcription occurs so that pre-tRNAs accumulate. The splicing reaction can be initiated by raising Mg2+ ions (> 5 mm) and enhanced by adding 1 mm hexamminecobalt chloride. Using the optimized system for the Nicotiana intron-containing tRNATyr gene, the precise initiation and termination sites of transcription and the splice sites were determined. The presence of 1 mm NAD+ in the reaction mixture leads to the removal of the 2' phosphate at the splice junction of tRNATyr, demonstrating the activity of a 2'-phosphotransferase in the tobacco nuclear extract. Many modified nucleosides such as m2G, m22G, m1A, phi27 and phi35 are introduced in either of the studied transcripts. As shown in other systems, the conversion of U35 to phi requires an intron-containing substrate.
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Affiliation(s)
- Y Yukawa
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
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35
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Abstract
In addition to directing transcription initiation, core promoters integrate input from distal regulatory elements. Except for rare exceptions, it has been generally found that eukaryotic tRNA and rRNA genes do not contain TATA promoter elements and instead use protein-protein interactions to bring the TATA-binding protein (TBP), to the core promoter. Genomewide analysis revealed TATA elements in the core promoters of tRNA and 5S rRNA (Pol III), U1 to U5 snRNA (Pol II), and 37S rRNA (Pol I) genes in Schizosaccharomyces pombe. Using tRNA-dependent suppression and other in vivo assays, as well as in vitro transcription, we demonstrated an obligatory requirement for upstream TATA elements for tRNA and 5S rRNA expression in S. pombe. The Pol III initiation factor Brf is found in complexes with TFIIIC and Pol III in S. pombe, while TBP is not, consistent with independent recruitment of TBP by TATA. Template commitment assays are consistent with this and confirm that the mechanisms of transcription complex assembly and initiation by Pol III in S. pombe differ substantially from those in other model organisms. The results were extended to large-rRNA synthesis, as mutation of the TATA element in the Pol I promoter also abolishes rRNA expression in fission yeast. A survey of other organisms' genomes reveals that a substantial number of eukaryotes may use widespread TATAs for transcription. These results indicate the presence of TATA-unified transcription systems in contemporary eukaryotes and provide insight into the residual need for TBP by all three Pols in other eukaryotes despite a lack of TATA elements in their promoters.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Base Sequence
- Conserved Sequence
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Evolution, Molecular
- Genome, Fungal
- Immunoblotting
- Molecular Sequence Data
- Promoter Regions, Genetic
- RNA Polymerase I/genetics
- RNA Polymerase I/metabolism
- RNA Polymerase II/genetics
- RNA Polymerase II/metabolism
- RNA Polymerase III/genetics
- RNA Polymerase III/metabolism
- RNA, Ribosomal/metabolism
- RNA, Ribosomal, 5S/genetics
- RNA, Transfer/metabolism
- Schizosaccharomyces/metabolism
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- TATA-Box Binding Protein
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic
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Affiliation(s)
- M Hamada
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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Arnaud P, Yukawa Y, Lavie L, Pélissier T, Sugiura M, Deragon JM. Analysis of the SINE S1 Pol III promoter from Brassica; impact of methylation and influence of external sequences. Plant J 2001; 26:295-305. [PMID: 11439118 DOI: 10.1046/j.1365-313x.2001.01029.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Transcription is an important control point in the transposable element mobilization process. To better understand the regulation of the plant SINE (Short Interspersed Elements) S1, its promoter sequence was studied using an in vitro pol III transcription system derived from tobacco cells. We show that the internal S1 promoter can be functional although upstream external sequences were found to enhance this basal level of transcription. For one putative 'master' locus (na7), three CAA triplets (in positions -12, -7 and -2) and two overlapping TATA motifs (in positions -54 to -43) were important to stimulate transcription. For this locus, two transcription initiation regions were characterized, one centered on position + 1 (first nucleotide of the S1 element) and one centered on position - 19 independently of the internal motifs. The CAA triplets only influence transcription in + 1 and work in association with the internal motifs. We show that methylation can inhibit transcription at the na7 locus. We also observe that S1 RNA is cleaved in a smaller Poly (A) minus product by a process analogous to the maturation of mammalian SINEs.
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Affiliation(s)
- P Arnaud
- CNRS UMR6547 and GDR2157, Biomove, Université Blaise Pascal Clermont-Ferrand II, 63177 Aubière Cedex, France
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