1
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Mattijssen S, Kerkhofs K, Stephen J, Yang A, Han CG, Tadafumi Y, Iben JR, Mishra S, Sakhawala RM, Ranjan A, Gowda M, Gahl WA, Gu S, Malicdan MC, Maraia RJ. A POLR3B-variant reveals a Pol III transcriptome response dependent on La protein/SSB. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.05.577363. [PMID: 38410490 PMCID: PMC10896340 DOI: 10.1101/2024.02.05.577363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
RNA polymerase III (Pol III, POLR3) synthesizes tRNAs and other small non-coding RNAs. Human POLR3 pathogenic variants cause a range of developmental disorders, recapitulated in part by mouse models, yet some aspects of POLR3 deficiency have not been explored. We characterized a human POLR3B:c.1625A>G;p.(Asn542Ser) disease variant that was found to cause mis-splicing of POLR3B. Genome-edited POLR3B1625A>G HEK293 cells acquired the mis-splicing with decreases in multiple POLR3 subunits and TFIIIB, although display auto-upregulation of the Pol III termination-reinitiation subunit POLR3E. La protein was increased relative to its abundant pre-tRNA ligands which bind via their U(n)U-3'-termini. Assays for cellular transcription revealed greater deficiencies for tRNA genes bearing terminators comprised of 4Ts than of ≥5Ts. La-knockdown decreased Pol III ncRNA expression unlinked to RNA stability. Consistent with these effects, small-RNAseq showed that POLR3B1625A>G and patient fibroblasts express more tRNA fragments (tRFs) derived from pre-tRNA 3'-trailers (tRF-1) than from mature-tRFs, and higher levels of multiple miRNAs, relative to control cells. The data indicate that decreased levels of Pol III transcripts can lead to functional excess of La protein which reshapes small ncRNA profiles revealing new depth in the Pol III system. Finally, patient cell RNA analysis uncovered a strategy for tRF-1/tRF-3 as POLR3-deficiency biomarkers.
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Affiliation(s)
- Sandy Mattijssen
- Section on Molecular and Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Kyra Kerkhofs
- Section on Molecular and Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Joshi Stephen
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Acong Yang
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702 USA
| | - Chen G. Han
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Yokoyama Tadafumi
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - James R. Iben
- Molecular Genetics Core, NICHD, NIH, Bethesda, MD 20892, USA
| | - Saurabh Mishra
- Section on Molecular and Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Rima M. Sakhawala
- Section on Molecular and Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Amitabh Ranjan
- Section on Molecular and Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Mamatha Gowda
- Department of Obstetrics & Gynaecology, Jawaharlal Institute of Post-Graduate Medical Education and Research, Puducherry, India
| | - William A. Gahl
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
- NIH Undiagnosed Diseases Program, NIH, Bethesda, MD 20892, USA
| | - Shuo Gu
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702 USA
| | - May C. Malicdan
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
- NIH Undiagnosed Diseases Program, NIH, Bethesda, MD 20892, USA
| | - Richard J. Maraia
- Section on Molecular and Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD 20892, USA
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2
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Yang DL, Huang K, Deng D, Zeng Y, Wang Z, Zhang Y. DNA-dependent RNA polymerases in plants. THE PLANT CELL 2023; 35:3641-3661. [PMID: 37453082 PMCID: PMC10533338 DOI: 10.1093/plcell/koad195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 06/09/2023] [Accepted: 05/29/2023] [Indexed: 07/18/2023]
Abstract
DNA-dependent RNA polymerases (Pols) transfer the genetic information stored in genomic DNA to RNA in all organisms. In eukaryotes, the typical products of nuclear Pol I, Pol II, and Pol III are ribosomal RNAs, mRNAs, and transfer RNAs, respectively. Intriguingly, plants possess two additional Pols, Pol IV and Pol V, which produce small RNAs and long noncoding RNAs, respectively, mainly for silencing transposable elements. The five plant Pols share some subunits, but their distinct functions stem from unique subunits that interact with specific regulatory factors in their transcription cycles. Here, we summarize recent advances in our understanding of plant nucleus-localized Pols, including their evolution, function, structures, and transcription cycles.
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Affiliation(s)
- Dong-Lei Yang
- National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 210095, China
| | - Kun Huang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Deyin Deng
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang Agriculture and Forestry University, Lin’an, Hangzhou 311300, China
| | - Yuan Zeng
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhenxing Wang
- College of Horticulture, National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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3
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Girbig M, Xie J, Grötsch H, Libri D, Porrua O, Müller CW. Architecture of the yeast Pol III pre-termination complex and pausing mechanism on poly(dT) termination signals. Cell Rep 2022; 40:111316. [PMID: 36070694 DOI: 10.1016/j.celrep.2022.111316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 07/01/2022] [Accepted: 08/15/2022] [Indexed: 12/20/2022] Open
Abstract
RNA polymerase (Pol) III is specialized to transcribe short, abundant RNAs, for which it terminates transcription on polythymine (dT) stretches on the non-template (NT) strand. When Pol III reaches the termination signal, it pauses and forms the pre-termination complex (PTC). Here, we report cryoelectron microscopy (cryo-EM) structures of the yeast Pol III PTC and complementary functional states at resolutions of 2.7-3.9 Å. Pol III recognizes the poly(dT) termination signal with subunit C128 that forms a hydrogen-bond network with the NT strand and, thereby, induces pausing. Mutating key interacting residues interferes with transcription termination in vitro, impairs yeast growth, and causes global termination defects in vivo, confirming our structural results. Additional cryo-EM analysis reveals that C53-C37, a Pol III subcomplex and key termination factor, participates indirectly in Pol III termination. We propose a mechanistic model of Pol III transcription termination and rationalize why Pol III, unlike Pol I and Pol II, terminates on poly(dT) signals.
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Affiliation(s)
- Mathias Girbig
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Juanjuan Xie
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Helga Grötsch
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Domenico Libri
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Odil Porrua
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France
| | - Christoph W Müller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany.
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4
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Structural insights into nuclear transcription by eukaryotic DNA-dependent RNA polymerases. Nat Rev Mol Cell Biol 2022; 23:603-622. [PMID: 35505252 DOI: 10.1038/s41580-022-00476-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2022] [Indexed: 02/07/2023]
Abstract
The eukaryotic transcription apparatus synthesizes a staggering diversity of RNA molecules. The labour of nuclear gene transcription is, therefore, divided among multiple DNA-dependent RNA polymerases. RNA polymerase I (Pol I) transcribes ribosomal RNA, Pol II synthesizes messenger RNAs and various non-coding RNAs (including long non-coding RNAs, microRNAs and small nuclear RNAs) and Pol III produces transfer RNAs and other short RNA molecules. Pol I, Pol II and Pol III are large, multisubunit protein complexes that associate with a multitude of additional factors to synthesize transcripts that largely differ in size, structure and abundance. The three transcription machineries share common characteristics, but differ widely in various aspects, such as numbers of RNA polymerase subunits, regulatory elements and accessory factors, which allows them to specialize in transcribing their specific RNAs. Common to the three RNA polymerases is that the transcription process consists of three major steps: transcription initiation, transcript elongation and transcription termination. In this Review, we outline the common principles and differences between the Pol I, Pol II and Pol III transcription machineries and discuss key structural and functional insights obtained into the three stages of their transcription processes.
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5
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Abstract
RNA polymerase III (Pol III) is a large multisubunit complex conserved in all eukaryotes that plays an essential role in producing a variety of short non-coding RNAs, such as tRNA, 5S rRNA and U6 snRNA transcripts. Pol III comprises of 17 subunits in both yeast and human with a 10-subunit core and seven peripheral subunits. Because of its size and complexity, Pol III has posed a formidable challenge to structural biologists. The first atomic cryogenic electron microscopy structure of yeast Pol III leading to the canonical view was reported in 2015. Within the last few years, the optimization of endogenous extract and purification procedure and the technical and methodological advances in cryogenic electron microscopy, together allow us to have a first look at the unprecedented details of human Pol III organization. Here, we look back on the structural studies of human Pol III and discuss them in the light of our current understanding of its role in eukaryotic transcription.
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Affiliation(s)
- Qianmin Wang
- Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute of Precision Medicine, Shanghai, China
| | - Ming Lei
- Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute of Precision Medicine, Shanghai, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jian Wu
- Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute of Precision Medicine, Shanghai, China
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6
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Chen Q, Ma K, Liu X, Chen SH, Li P, Yu Y, Leung AKL, Yu X. Truncated PARP1 mediates ADP-ribosylation of RNA polymerase III for apoptosis. Cell Discov 2022; 8:3. [PMID: 35039483 PMCID: PMC8764063 DOI: 10.1038/s41421-021-00355-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 11/09/2021] [Indexed: 11/18/2022] Open
Abstract
Caspase-mediated cleavage of PARP1 is a surrogate marker for apoptosis. However, the biological significance of PARP1 cleavage during apoptosis is still unclear. Here, using unbiased protein affinity purification, we show that truncated PARP1 (tPARP1) recognizes the RNA polymerase III (Pol III) complex in the cytosol. tPARP1 mono-ADP-ribosylates RNA Pol III in vitro and mediates ADP-ribosylation of RNA Pol III during poly(dA-dT)-stimulated apoptosis in cells. tPARP1-mediated activation of RNA Pol III facilitates IFN-β production and apoptosis. In contrast, suppression of PARP1 or expressing the non-cleavable form of PARP1 impairs these molecular events. Taken together, these studies reveal a novel biological role of tPARP1 during cytosolic DNA-induced apoptosis.
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Affiliation(s)
- Qian Chen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA.
| | - Kai Ma
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Xiuhua Liu
- College of Life Sciences, Hebei University, Baoding, Hebei, China
| | - Shih-Hsun Chen
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan, China
| | - Peng Li
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yonghao Yu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Anthony K L Leung
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Department of Molecular Biology and Genetics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.,Department of Oncology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Xiaochun Yu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA. .,Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China. .,School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China. .,Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China.
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7
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Kessler AC, Maraia RJ. The nuclear and cytoplasmic activities of RNA polymerase III, and an evolving transcriptome for surveillance. Nucleic Acids Res 2021; 49:12017-12034. [PMID: 34850129 PMCID: PMC8643620 DOI: 10.1093/nar/gkab1145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/26/2021] [Accepted: 11/02/2021] [Indexed: 12/23/2022] Open
Abstract
A 1969 report that described biochemical and activity properties of the three eukaryotic RNA polymerases revealed Pol III as highly distinguishable, even before its transcripts were identified. Now known to be the most complex, Pol III contains several stably-associated subunits referred to as built-in transcription factors (BITFs) that enable highly efficient RNA synthesis by a unique termination-associated recycling process. In vertebrates, subunit RPC7(α/β) can be of two forms, encoded by POLR3G or POLR3GL, with differential activity. Here we review promoter-dependent transcription by Pol III as an evolutionary perspective of eukaryotic tRNA expression. Pol III also provides nonconventional functions reportedly by promoter-independent transcription, one of which is RNA synthesis from DNA 3'-ends during repair. Another is synthesis of 5'ppp-RNA signaling molecules from cytoplasmic viral DNA in a pathway of interferon activation that is dysfunctional in immunocompromised patients with mutations in Pol III subunits. These unconventional functions are also reviewed, including evidence that link them to the BITF subunits. We also review data on a fraction of the human Pol III transcriptome that evolved to include vault RNAs and snaRs with activities related to differentiation, and in innate immune and tumor surveillance. The Pol III of higher eukaryotes does considerably more than housekeeping.
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Affiliation(s)
- Alan C Kessler
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892 USA
| | - Richard J Maraia
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892 USA
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8
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Mishra S, Hasan SH, Sakhawala RM, Chaudhry S, Maraia RJ. Mechanism of RNA polymerase III termination-associated reinitiation-recycling conferred by the essential function of the N terminal-and-linker domain of the C11 subunit. Nat Commun 2021; 12:5900. [PMID: 34625550 PMCID: PMC8501072 DOI: 10.1038/s41467-021-26080-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 09/17/2021] [Indexed: 01/06/2023] Open
Abstract
RNA polymerase III achieves high level tRNA synthesis by termination-associated reinitiation-recycling that involves the essential C11 subunit and heterodimeric C37/53. The C11-CTD (C-terminal domain) promotes Pol III active center-intrinsic RNA 3'-cleavage although deciphering function for this activity has been complicated. We show that the isolated NTD (N-terminal domain) of C11 stimulates Pol III termination by C37/53 but not reinitiation-recycling which requires the NTD-linker (NTD-L). By an approach different from what led to current belief that RNA 3'-cleavage activity is essential, we show that NTD-L can provide the essential function of Saccharomyces cerevisiae C11 whereas classic point mutations that block cleavage, interfere with active site function and are toxic to growth. Biochemical and in vivo analysis including of the C11 invariant central linker led to a model for Pol III termination-associated reinitiation-recycling. The C11 NTD and CTD stimulate termination and RNA 3'-cleavage, respectively, whereas reinitiation-recycling activity unique to Pol III requires only the NTD-linker. RNA 3'-cleavage activity increases growth rate but is nonessential.
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Affiliation(s)
- Saurabh Mishra
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Department of Biochemistry, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Shaina H Hasan
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Mayo Clinic Alix School of Medicine, Scottsdale, AZ, USA
| | - Rima M Sakhawala
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Section on Regulatory RNA, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Shereen Chaudhry
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Pfizer (Pearl River Site), 401 N Middletown Rd, Pearl River, NY, USA
| | - Richard J Maraia
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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9
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Shukla A, Bhalla P, Potdar PK, Jampala P, Bhargava P. Transcription-dependent enrichment of the yeast FACT complex influences nucleosome dynamics on the RNA polymerase III-transcribed genes. RNA (NEW YORK, N.Y.) 2020; 27:rna.077974.120. [PMID: 33277439 PMCID: PMC7901838 DOI: 10.1261/rna.077974.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 11/30/2020] [Indexed: 05/04/2023]
Abstract
The FACT (FAcilitates Chromatin Transactions) complex influences transcription initiation and enables passage of RNA polymerase (pol) II through gene body nucleosomes during elongation. In the budding yeast, ~280 non-coding RNA genes highly transcribed in vivo by pol III are found in the nucleosome-free regions bordered by positioned nucleosomes. The downstream nucleosome dynamics was found to regulate transcription via controlling the gene terminator accessibility and hence, terminator-dependent pol III recycling. As opposed to the enrichment at the 5'-ends of pol II-transcribed genes, our genome-wide mapping found transcription-dependent enrichment of the FACT subunit Spt16 near the 3'-end of all pol III-transcribed genes. Spt16 physically associates with the pol III transcription complex and shows gene-specific occupancy levels on the individual genes. On the non-tRNA pol III-transcribed genes, Spt16 facilitates transcription by reducing the nucleosome occupany on the gene body. On the tRNA genes, it maintains the position of the nucleosome at the 3' gene-end and affects transcription in gene-specific manner. Under nutritional stress, Spt16 enrichment is abolished in the gene downstream region of all pol III-transcribed genes and reciprocally changed on the induced or repressed pol II-transcribed ESR genes. Under the heat and replicative stress, its occupancy on the pol III-transcribed genes increases significantly. Our results show that Spt16 elicits a differential, gene-specific and stress-responsive dynamics, which provides a novel stress-sensor mechanism of regulating transcription against external stress. By primarily influencing the nucleosomal organization, FACT links the downstream nucleosome dynamics to transcription and environmental stress on the pol III-transcribed genes.
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10
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Scull CE, Ingram ZM, Lucius AL, Schneider DA. A Novel Assay for RNA Polymerase I Transcription Elongation Sheds Light on the Evolutionary Divergence of Eukaryotic RNA Polymerases. Biochemistry 2019; 58:2116-2124. [PMID: 30912638 PMCID: PMC6600827 DOI: 10.1021/acs.biochem.8b01256] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Eukaryotic cells express at least three nuclear RNA polymerases (Pols), each with a unique set of gene targets. Though these enzymes are homologous, there are many differences among the Pols. In this study, a novel assay for Pol I transcription elongation was developed to probe enzymatic differences among the Pols. In Saccharomyces cerevisiae, a mutation in the universally conserved hinge region of the trigger loop, E1103G, induces a gain of function in the Pol II elongation rate, whereas the corresponding mutation in Pol I, E1224G, results in a loss of function. The E1103G Pol II mutation stabilizes the closed conformation of the trigger loop, promoting the catalytic step, the putative rate-limiting step for Pol II. In single-nucleotide and multinucleotide addition assays, we observe a decrease in the rate of nucleotide addition and dinucleotide cleavage activity by E1224G Pol I and an increase in the rate of misincorporation. Collectively, these data suggest that Pol I is at least in part rate-limited by the same step as Pol II, the catalytic step.
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Affiliation(s)
- Catherine E. Scull
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Zachariah M. Ingram
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Aaron L. Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - David A. Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
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11
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Qiu C, Kaplan CD. Functional assays for transcription mechanisms in high-throughput. Methods 2019; 159-160:115-123. [PMID: 30797033 PMCID: PMC6589137 DOI: 10.1016/j.ymeth.2019.02.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/18/2019] [Indexed: 01/12/2023] Open
Abstract
Dramatic increases in the scale of programmed synthesis of nucleic acid libraries coupled with deep sequencing have powered advances in understanding nucleic acid and protein biology. Biological systems centering on nucleic acids or encoded proteins greatly benefit from such high-throughput studies, given that large DNA variant pools can be synthesized and DNA, or RNA products of transcription, can be easily analyzed by deep sequencing. Here we review the scope of various high-throughput functional assays for studies of nucleic acids and proteins in general, followed by discussion of how these types of study have yielded insights into the RNA Polymerase II (Pol II) active site as an example. We discuss methodological considerations in the design and execution of these experiments that should be valuable to studies in any system.
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Affiliation(s)
- Chenxi Qiu
- Department of Medicine, Division of Translational Therapeutics, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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12
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Mishra S, Maraia RJ. RNA polymerase III subunits C37/53 modulate rU:dA hybrid 3' end dynamics during transcription termination. Nucleic Acids Res 2019; 47:310-327. [PMID: 30407541 PMCID: PMC6326807 DOI: 10.1093/nar/gky1109] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 10/22/2018] [Indexed: 12/18/2022] Open
Abstract
RNA polymerase (RNAP) III synthesizes tRNAs and other transcripts, and mutations to its subunits cause human disorders. The RNAP III subunit-heterodimer C37/53 functions in initiation, elongation and in termination-associated reinitiation with subunit C11. C37/53 is related to heterodimers associated with RNAPs I and II, and C11 is related to TFIIS and Rpa12.2, the active site RNA 3' cleavage factors for RNAPs II and I. Critical to termination is stability of the RNA:DNA hybrid bound in the active center, which is loose for RNAP III relative to other RNAPs. Here, we examined RNAP III lacking C37/53/C11 and various reconstituted forms during termination. First, we established a minimal terminator as 5T and 3A on the non-template and template DNA strands, respectively. We demonstrate that C11 stimulates termination, and does so independently of its RNA cleavage activity. We found that C37/53 sensitizes RNAP III termination to RNA:DNA hybrid strength and promotes RNA 3' end pairing/annealing with the template. The latter counteracts C11-insensitive arrest in the proximal part of the oligo(T)-tract, promoting oligo(rU:dA) extension toward greater hybrid instability and RNA release. The data also indicate that RNA 3' end engagement with the active site is a determinant of termination. Broader implications are also discussed.
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Affiliation(s)
- Saurabh Mishra
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard J Maraia
- Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
- Commissioned Corps, U.S. Public Health Service, Rockville, MD 20852, USA
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13
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Leśniewska E, Boguta M. Novel layers of RNA polymerase III control affecting tRNA gene transcription in eukaryotes. Open Biol 2017; 7:rsob.170001. [PMID: 28228471 PMCID: PMC5356446 DOI: 10.1098/rsob.170001] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 01/31/2017] [Indexed: 12/20/2022] Open
Abstract
RNA polymerase III (Pol III) transcribes a limited set of short genes in eukaryotes producing abundant small RNAs, mostly tRNA. The originally defined yeast Pol III transcriptome appears to be expanding owing to the application of new methods. Also, several factors required for assembly and nuclear import of Pol III complex have been identified recently. Models of Pol III based on cryo-electron microscopy reconstructions of distinct Pol III conformations reveal unique features distinguishing Pol III from other polymerases. Novel concepts concerning Pol III functioning involve recruitment of general Pol III-specific transcription factors and distinctive mechanisms of transcription initiation, elongation and termination. Despite the short length of Pol III transcription units, mapping of transcriptionally active Pol III with nucleotide resolution has revealed strikingly uneven polymerase distribution along all genes. This may be related, at least in part, to the transcription factors bound at the internal promoter regions. Pol III uses also a specific negative regulator, Maf1, which binds to polymerase under stress conditions; however, a subset of Pol III genes is not controlled by Maf1. Among other RNA polymerases, Pol III machinery represents unique features related to a short transcript length and high transcription efficiency.
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Affiliation(s)
- Ewa Leśniewska
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Magdalena Boguta
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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Trigger loop dynamics can explain stimulation of intrinsic termination by bacterial RNA polymerase without terminator hairpin contact. Proc Natl Acad Sci U S A 2017; 114:E9233-E9242. [PMID: 29078293 DOI: 10.1073/pnas.1706247114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
In bacteria, intrinsic termination signals cause disassembly of the highly stable elongating transcription complex (EC) over windows of two to three nucleotides after kilobases of RNA synthesis. Intrinsic termination is caused by the formation of a nascent RNA hairpin adjacent to a weak RNA-DNA hybrid within RNA polymerase (RNAP). Although the contributions of RNA and DNA sequences to termination are largely understood, the roles of conformational changes in RNAP are less well described. The polymorphous trigger loop (TL), which folds into the trigger helices to promote nucleotide addition, also is proposed to drive termination by folding into the trigger helices and contacting the terminator hairpin after invasion of the hairpin in the RNAP main cleft [Epshtein V, Cardinale CJ, Ruckenstein AE, Borukhov S, Nudler E (2007) Mol Cell 28:991-1001]. To investigate the contribution of the TL to intrinsic termination, we developed a kinetic assay that distinguishes effects of TL alterations on the rate at which ECs terminate from effects of the TL on the nucleotide addition rate that indirectly affect termination efficiency by altering the time window in which termination can occur. We confirmed that the TL stimulates termination rate, but found that stabilizing either the folded or unfolded TL conformation decreased termination rate. We propose that conformational fluctuations of the TL (TL dynamics), not TL-hairpin contact, aid termination by increasing EC conformational diversity and thus access to favorable termination pathways. We also report that the TL and the TL sequence insertion (SI3) increase overall termination efficiency by stimulating pausing, which increases the flux of ECs into the termination pathway.
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