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Hemleben V, Grierson D, Borisjuk N, Volkov RA, Kovarik A. Personal Perspectives on Plant Ribosomal RNA Genes Research: From Precursor-rRNA to Molecular Evolution. FRONTIERS IN PLANT SCIENCE 2021; 12:797348. [PMID: 34992624 PMCID: PMC8724763 DOI: 10.3389/fpls.2021.797348] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
The history of rDNA research started almost 90 years ago when the geneticist, Barbara McClintock observed that in interphase nuclei of maize the nucleolus was formed in association with a specific region normally located near the end of a chromosome, which she called the nucleolar organizer region (NOR). Cytologists in the twentieth century recognized the nucleolus as a common structure in all eukaryotic cells, using both light and electron microscopy and biochemical and genetic studies identified ribosomes as the subcellular sites of protein synthesis. In the mid- to late 1960s, the synthesis of nuclear-encoded rRNA was the only system in multicellular organisms where transcripts of known function could be isolated, and their synthesis and processing could be studied. Cytogenetic observations of NOR regions with altered structure in plant interspecific hybrids and detailed knowledge of structure and function of rDNA were prerequisites for studies of nucleolar dominance, epistatic interactions of rDNA loci, and epigenetic silencing. In this article, we focus on the early rDNA research in plants, performed mainly at the dawn of molecular biology in the 60 to 80-ties of the last century which presented a prequel to the modern genomic era. We discuss - from a personal view - the topics such as synthesis of rRNA precursor (35S pre-rRNA in plants), processing, and the organization of 35S and 5S rDNA. Cloning and sequencing led to the observation that the transcribed and processed regions of the rRNA genes vary enormously, even between populations and species, in comparison with the more conserved regions coding for the mature rRNAs. Epigenetic phenomena and the impact of hybridization and allopolyploidy on rDNA expression and homogenization are discussed. This historical view of scientific progress and achievements sets the scene for the other articles highlighting the immense progress in rDNA research published in this special issue of Frontiers in Plant Science on "Molecular organization, evolution, and function of ribosomal DNA."
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Affiliation(s)
- Vera Hemleben
- Center of Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Donald Grierson
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Nikolai Borisjuk
- School of Life Sciences, Huaiyin Normal University, Huai'an, China
| | - Roman A. Volkov
- Department of Molecular Genetics and Biotechnology, Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine
| | - Ales Kovarik
- Laboratory of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
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Xu L, Li Z, Wang S. Development of a Virus-Based Reporter System for Functional Analysis of Plant rRNA Gene Promoter. Front Microbiol 2021; 12:637347. [PMID: 33679673 PMCID: PMC7928365 DOI: 10.3389/fmicb.2021.637347] [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: 12/08/2020] [Accepted: 01/25/2021] [Indexed: 11/27/2022] Open
Abstract
Reporter gene-based expression systems have been intensively used in plants for monitoring the activity of gene promoters. However, rRNA transcripts are unable to efficiently express a reporter gene due to a lack of a 5' cap. Because of this obstacle, plant rRNA gene promoters are less well characterized to this day. We developed a virus-based reporter system to characterize the Nicotiana benthamiana rRNA (NbrRNA) gene promoter. The system utilizes the cap-independent translation strategy of viral genomic mRNA and uses the virus-expressed green fluorescent protein (GFP) as an indicator of the rRNA gene promoter activity in virus-infected plants. Based on the reporter system, some characteristics of the N. benthamiana rRNA gene promoter were revealed. The results showed that the strength of the NbrRNA gene promoter was lower than that of the cauliflower mosaic virus (CaMV) 35S promoter, a well-characterized polymerase II promoter. The sequences between −77 and +42 are sufficient for the NbrRNA gene promoter-mediated transcription and the NbrRNA gene promoter may lack the functional upstream control element (UCE). Interestingly, NbrRNA gene promoter activity was increased when the 35S enhancer was introduced. An intron-excision mediated assay revealed that the NbrRNA gene promoter can be inefficiently used by RNA polymerase II in N. benthamiana cells. This virus-based reporter system is easier to operate and more convenient when compared with the previously Pol I promoter assays. And it offers a promising solution to analyzing the functional architecture of plant rRNA gene promoter.
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Affiliation(s)
- Li Xu
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, School of Life Science, Ningxia University, Yinchuan, China
| | - Zhiying Li
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, School of Life Science, Ningxia University, Yinchuan, China.,Key Laboratory of Modern Molecular Breeding for Dominant and Special Crops in Ningxia, School of Life Science, Ningxia University, Yinchuan, China
| | - Sheng Wang
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, School of Life Science, Ningxia University, Yinchuan, China.,Key Laboratory of Modern Molecular Breeding for Dominant and Special Crops in Ningxia, School of Life Science, Ningxia University, Yinchuan, China
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Georgiev O, Mishev K, Krasnikova M, Kitanova M, Dimitrova A, Karagyozov L. The Hordeum bulbosum 25S-18S rDNA region: comparison with Hordeum vulgare and other Triticeae. ACTA ACUST UNITED AC 2019; 74:319-328. [PMID: 31421048 DOI: 10.1515/znc-2018-0109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 07/18/2019] [Indexed: 11/15/2022]
Abstract
Hordeum vulgare and Hordeum bulbosum are two closely related barley species, which share a common H genome. H. vulgare has two nucleolar organizer regions (NORs), while the NOR of H. bulbosum is only one. We sequenced the 2.5 kb 25S-18S region in the rDNA of H. bulbosum and compared it to the same region in H. vulgare as well as to the other Triticeae. The region includes an intergenic spacer (IGS) with a number of subrepeats, a promoter, and an external transcribed spacer (5'ETS). The IGS of H. bulbosum downstream of 25S rRNA contains two 143-bp repeats and six 128-bp repeats. In contrast, the IGS in H. vulgare contains an array of seven 79-bp repeats and a varying number of 135-bp repeats. The 135-bp repeats in H. vulgare and the 128-bp repeats in H. bulbosum show similarity. Compared to H. vulgare, the 5'ETS of H. bulbosum is shorter. Additionally, the 5'ETS regions in H. bulbosum and H. vulgare diverged faster than in other Triticeae genera. Alignment of the Triticeae promoter sequences suggests that in Hordeum, as in diploid Triticum, transcription starts with guanine and not with adenine as it is in many other plants.
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Affiliation(s)
- Oleg Georgiev
- Institute of Molecular Life Sciences, University Zurich-Irchel, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Kiril Mishev
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
| | - Maria Krasnikova
- Department of Genetics, Faculty of Biology, St. Kl. Ohridsky University of Sofia, 8 Dragan Tsankov bld., 1164 Sofia, Bulgaria
| | - Meglena Kitanova
- Department of Genetics, Faculty of Biology, St. Kl. Ohridsky University of Sofia, 8 Dragan Tsankov bld., 1164 Sofia, Bulgaria
| | - Anna Dimitrova
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria, Phone: +359 2 9792677, Fax: +359 2 9785516, E-mail:
| | - Luchezar Karagyozov
- Department of Genetics, Faculty of Biology, St. Kl. Ohridsky University of Sofia, 8 Dragan Tsankov bld., 1164 Sofia, Bulgaria
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Dal Santo S, Tornielli GB, Zenoni S, Fasoli M, Farina L, Anesi A, Guzzo F, Delledonne M, Pezzotti M. The plasticity of the grapevine berry transcriptome. Genome Biol 2013; 14:r54. [PMID: 23759170 PMCID: PMC3706941 DOI: 10.1186/gb-2013-14-6-r54] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/15/2013] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Phenotypic plasticity refers to the range of phenotypes a single genotype can express as a function of its environment. These phenotypic variations are attributable to the effect of the environment on the expression and function of genes influencing plastic traits. We investigated phenotypic plasticity in grapevine by comparing the berry transcriptome in a single clone of the vegetatively-propagated common grapevine species Vitis vinifera cultivar Corvina through 3 consecutive growth years cultivated in 11 different vineyards in the Verona area of Italy. RESULTS Most of the berry transcriptome clustered by year of growth rather than common environmental conditions or viticulture practices, and transcripts related to secondary metabolism showed high sensitivity towards different climates, as confirmed also by metabolomic data obtained from the same samples. When analyzed in 11 vineyards during 1 growth year, the environmentally-sensitive berry transcriptome comprised 5% of protein-coding genes and 18% of the transcripts modulated during berry development. Plastic genes were particularly enriched in ontology categories such as transcription factors, translation, transport, and secondary metabolism. Specific plastic transcripts were associated with groups of vineyards sharing common viticulture practices or environmental conditions, and plastic transcriptome reprogramming was more intense in the year characterized by extreme weather conditions. We also identified a set of genes that lacked plasticity, showing either constitutive expression or similar modulation in all berries. CONCLUSIONS Our data reveal candidate genes potentially responsible for the phenotypic plasticity of grapevine and provide the first step towards the characterization of grapevine transcriptome plasticity under different agricultural systems.
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Affiliation(s)
- Silvia Dal Santo
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
| | | | - Sara Zenoni
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
| | - Marianna Fasoli
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
| | - Lorenzo Farina
- Department of Computer, Control, and Management Engineering Antonio Ruberti, Sapienza University of Rome, Via Ariosto 25, 00185 Rome, Italy
| | - Andrea Anesi
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
| | - Flavia Guzzo
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
| | - Massimo Delledonne
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
| | - Mario Pezzotti
- Department of Biotechnology, University of Verona, Strada Le Grazie 15 - Ca' Vignal, 37134 Verona, Italy
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Matsunaga S, Katagiri Y, Nagashima Y, Sugiyama T, Hasegawa J, Hayashi K, Sakamoto T. New insights into the dynamics of plant cell nuclei and chromosomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:253-301. [PMID: 23890384 DOI: 10.1016/b978-0-12-407695-2.00006-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plant lamin-like protein NMCP/AtLINC and orthologues of the SUN-KASH complex across the nuclear envelope (NE) show the universality of nuclear structure in eukaryotes. However, depletion of components in the connection complex of the NE in plants does not induce severe defects, unlike in animals. Appearance of the Rabl configuration is not dependent on genome size in plant species. Topoisomerase II and condensin II are not essential for plant chromosome condensation. Plant endoreduplication shares several common characteristics with animals, including involvement of cyclin-dependent kinases and E2F transcription factors. Recent finding regarding endomitosis regulator GIG1 shed light on the suppression mechanism of endomitosis in plants. The robustness of plants, compared with animals, is reflected in their genome redundancy. Spatiotemporal functional analyses using chromophore-assisted light inactivation, super-resolution microscopy, and 4D (3D plus time) imaging will reveal new insights into plant nuclear and chromosomal dynamics.
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Affiliation(s)
- Sachihiro Matsunaga
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan.
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Garcia S, Crhák Khaitová L, Kovařík A. Expression of 5 S rRNA genes linked to 35 S rDNA in plants, their epigenetic modification and regulatory element divergence. BMC PLANT BIOLOGY 2012; 12:95. [PMID: 22716941 PMCID: PMC3409069 DOI: 10.1186/1471-2229-12-95] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/20/2012] [Indexed: 05/09/2023]
Abstract
BACKGROUND In plants, the 5 S rRNA genes usually occur as separate tandems (S-type arrangement) or, less commonly, linked to 35 S rDNA units (L-type). The activity of linked genes remains unknown so far. We studied the homogeneity and expression of 5 S genes in several species from family Asteraceae known to contain linked 35 S-5 S units. Additionally, their methylation status was determined using bisulfite sequencing. Fluorescence in situ hybridization was applied to reveal the sub-nuclear positions of rDNA arrays. RESULTS We found that homogenization of L-type units went to completion in most (4/6) but not all species. Two species contained major L-type and minor S-type units (termed L(s)-type). The linked genes dominate 5 S rDNA expression while the separate tandems do not seem to be expressed. Members of tribe Anthemideae evolved functional variants of the polymerase III promoter in which a residing C-box element differs from the canonical angiosperm motif by as much as 30%. On this basis, a more relaxed consensus sequence of a plant C-box: (5'-RGSWTGGGTG-3') is proposed. The 5 S paralogs display heavy DNA methylation similarly as to their unlinked counterparts. FISH revealed the close association of 35 S-5 S arrays with nucleolar periphery indicating that transcription of 5 S genes may occur in this territory. CONCLUSIONS We show that the unusual linked arrangement of 5 S genes, occurring in several plant species, is fully compatible with their expression and functionality. This extraordinary 5 S gene dynamics is manifested at different levels, such as variation in intrachromosomal positions, unit structure, epigenetic modification and considerable divergence of regulatory motifs.
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MESH Headings
- Animals
- Asteraceae/chemistry
- Asteraceae/genetics
- Asteraceae/metabolism
- Base Sequence
- Consensus Sequence
- DNA Methylation
- DNA, Plant/chemistry
- DNA, Plant/genetics
- DNA, Plant/metabolism
- Epigenesis, Genetic
- Evolution, Molecular
- Gene Expression Regulation, Plant
- Molecular Sequence Data
- Promoter Regions, Genetic
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- Regulatory Sequences, Nucleic Acid
- Response Elements
- Sequence Alignment
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Affiliation(s)
- Sònia Garcia
- Laboratori de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s. n., Barcelona, Catalonia, 08028, Spain
| | - Lucie Crhák Khaitová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, Brno, CZ-6125, Czech Republic
| | - Aleš Kovařík
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, Brno, CZ-6125, Czech Republic
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Lahmy S, Pontier D, Cavel E, Vega D, El-Shami M, Kanno T, Lagrange T. PolV(PolIVb) function in RNA-directed DNA methylation requires the conserved active site and an additional plant-specific subunit. Proc Natl Acad Sci U S A 2009; 106:941-6. [PMID: 19141635 PMCID: PMC2630096 DOI: 10.1073/pnas.0810310106] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Indexed: 01/22/2023] Open
Abstract
Two forms of a plant-specific RNA polymerase (Pol), PolIV(PolIVa) and PolV(PolIVb), currently defined by their respective largest subunits [NRPD1(NRPD1a) and NRPE1(NRPD1b)], have been implicated in the production and activity of 24-nt small RNAs (sRNAs) in RNA-directed DNA methylation (RdDM). Prevailing models support the view that PolIV(PolIVa) plays an upstream role in RdDM by producing the 24-nt sRNAs, whereas PolV(PolIVb) would act downstream at a structural rather than an enzymatic level to reinforce sRNA production by PolIV(PolIVa) and mediate DNA methylation. However, the composition and mechanism of action of PolIV(PolIVa)/PolV(PolIVb) remain unclear. In this work, we have identified a plant-specific PolV(PolIVb) subunit, NRPE5a, homologous to NRPB5a, a common subunit shared by PolI-III and shown here to be present in PolIV(PolIVa). Our results confirm the combinatorial diversity of PolIV(PolIVa)/PolV(PolIVb) subunit composition and indicate that these plant-specific Pols are eukaryotic-type polymerases. Moreover, we show that nrpe5a-1 mutation differentially impacts sRNAs accumulation at various PolIV(PolIVa)/PolV(PolIVb)-dependent loci, indicating a target-specific requirement for NRPE5a in the process of PolV(PolIVb)-dependent gene silencing. We then describe that the triad aspartate motif present in the catalytic center of PolV(PolIVb) is required for recapitulation of all activities associated with this Pol complex in RdDM, suggesting that RNA polymerization is important for PolV(PolIVb) to perform its regulatory functions.
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Affiliation(s)
- Sylvie Lahmy
- Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique/Institut de Recherche et Développement/Université de Perpignan, 66860 Perpignan Cedex, France; and
| | - Dominique Pontier
- Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique/Institut de Recherche et Développement/Université de Perpignan, 66860 Perpignan Cedex, France; and
| | - Emilie Cavel
- Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique/Institut de Recherche et Développement/Université de Perpignan, 66860 Perpignan Cedex, France; and
| | - Danielle Vega
- Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique/Institut de Recherche et Développement/Université de Perpignan, 66860 Perpignan Cedex, France; and
| | - Mahmoud El-Shami
- Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique/Institut de Recherche et Développement/Université de Perpignan, 66860 Perpignan Cedex, France; and
| | - Tatsuo Kanno
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, A-1030 Vienna, Austria
| | - Thierry Lagrange
- Laboratoire Génome et Développement des Plantes, Centre National de la Recherche Scientifique/Institut de Recherche et Développement/Université de Perpignan, 66860 Perpignan Cedex, France; and
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Onodera Y, Haag JR, Ream T, Costa Nunes P, Pontes O, Pikaard CS. Plant nuclear RNA polymerase IV mediates siRNA and DNA methylation-dependent heterochromatin formation. Cell 2005; 120:613-22. [PMID: 15766525 DOI: 10.1016/j.cell.2005.02.007] [Citation(s) in RCA: 455] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Revised: 01/24/2005] [Accepted: 02/04/2005] [Indexed: 10/25/2022]
Abstract
All eukaryotes have three nuclear DNA-dependent RNA polymerases, namely, Pol I, II, and III. Interestingly, plants have catalytic subunits for a fourth nuclear polymerase, Pol IV. Genetic and biochemical evidence indicates that Pol IV does not functionally overlap with Pol I, II, or III and is nonessential for viability. However, disruption of the Pol IV catalytic subunit genes NRPD1 or NRPD2 inhibits heterochromatin association into chromocenters, coincident with losses in cytosine methylation at pericentromeric 5S gene clusters and AtSN1 retroelements. Loss of CG, CNG, and CNN methylation in Pol IV mutants implicates a partnership between Pol IV and the methyltransferase responsible for RNA-directed de novo methylation. Consistent with this hypothesis, 5S gene and AtSN1 siRNAs are essentially eliminated in Pol IV mutants. The data suggest that Pol IV helps produce siRNAs that target de novo cytosine methylation events required for facultative heterochromatin formation and higher-order heterochromatin associations.
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Affiliation(s)
- Yasuyuki Onodera
- Biology Department, Washington University, 1 Brookings Drive, St. Louis, MO 63130, USA
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Saez-Vasquez J, Albert AC, Earley K, Pikaard CS. Purification and transcriptional analysis of RNA polymerase I holoenzymes from broccoli (Brassica oleracea) and frog (Xenopus laevis). Methods Enzymol 2004; 370:121-38. [PMID: 14712639 DOI: 10.1016/s0076-6879(03)70011-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Affiliation(s)
- Julio Saez-Vasquez
- Biology Department, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, USA
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10
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Hemleben V, Volkov RA, Zentgraf U, Medina FJ. Molecular Cell Biology: Organization and Molecular Evolution of rDNA, Nucleolar Dominance, and Nucleolus Structure. PROGRESS IN BOTANY 2004. [DOI: 10.1007/978-3-642-18819-0_5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Pikaard CS. Transcription and tyranny in the nucleolus: the organization, activation, dominance and repression of ribosomal RNA genes. THE ARABIDOPSIS BOOK 2002; 1:e0083. [PMID: 22303219 PMCID: PMC3243331 DOI: 10.1199/tab.0083] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Affiliation(s)
- Craig S Pikaard
- Biology Department, Washington University, Campus box 1137, 1 Brookings Drive, St. Louis, Missouri, 63130, USA ; FAX: 314-935-4432;
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Akhunov ED, Chemeris AV, Kulikov AM, Vakhitov VA. Functional analysis of diploid wheat rRNA promoter by transient expression. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1522:226-9. [PMID: 11779639 DOI: 10.1016/s0167-4781(01)00336-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The rRNA gene promoter regions of three diploid wheats Triticum boeoticum Boiss, Triticum urartu Tum. ex Gandil, and Triticum monococcum L. have been sequenced and analyzed. It has been found that the rRNA promoter initiation regions of diploid wheats contain the sequences, which differ from the evolutionary conserved TATAGTAGG (+1 is underlined) motif of monocots. The transient expression assay in wheat protoplasts confirmed that cloned sequences are active promoters. Deletion analysis showed that the promoter sequence localized between -113 and +15 (relative to +1) is enough to direct RNA polymerase I-dependent transcription.
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Affiliation(s)
- E D Akhunov
- Department of Agronomy and Range Science, University of California, Davis, CA 95616, USA.
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Abstract
In eukaryotes, holoenzymes are large preassembled complexes containing RNA polymerases and variable sets of general transcription initiation factors and cofactors that are important for the regulation of gene expression. Recent advances in purification and characterization of RNA polymerase I holoenzyme from plants provide experimental data suggesting that it plays a key role in transcriptional regulation. These findings have a significant implication on our understanding of the mechanisms of promoter recognition, assembly of transcription initiation complexes, RNA chain elongation and transcription termination.
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Affiliation(s)
- A Kenzior
- Dept of Biochemistry, University of Missouri - Columbia, Columbia, MO 65211, USA
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