Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
1.
Nature ; 604(7904): 184-189, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35114687

RESUMEN

NLRP3 is an intracellular sensor protein that when activated by a broad spectrum of exogenous and endogenous stimuli leads to inflammasome formation and pyroptosis1,2. The conformational states of NLRP3 and the way antagonistic small molecules act at the molecular level remain poorly understood2,3. Here we report the cryo-electron microscopy structures of full-length human NLRP3 in its native form and complexed with the inhibitor CRID3 (also named MCC950)4. Inactive, ADP-bound NLRP3 is a decamer composed of homodimers of intertwined leucine-rich repeat (LRR) domains that assemble back-to-back as pentamers. The NACHT domain is located at the apical axis of this spherical structure. One pyrin domain dimer is in addition formed inside the LRR cage. Molecular contacts between the concave sites of two opposing LRR domains are mediated by an acidic loop that extends from an LRR transition segment. Binding of CRID3 considerably stabilizes the NACHT and LRR domains relative to each other. CRID3 binds into a cleft, connecting four subdomains of the NACHT with the transition LRR. Its central sulfonylurea group interacts with the Walker A motif of the NLRP3 nucleotide-binding domain and is sandwiched between two arginine residues, which explains the specificity of NLRP3 for this chemical entity. With the determination of the binding site of this key therapeutic agent, specific targeting of NLRP3 for the treatment of autoinflammatory and autoimmune diseases and rational drug optimization is within reach.


Asunto(s)
Furanos , Indenos , Proteína con Dominio Pirina 3 de la Familia NLR , Sulfonamidas , Microscopía por Crioelectrón , Furanos/química , Humanos , Indenos/química , Inflamasomas/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/química , Conformación Proteica , Sulfonamidas/química
2.
Nucleic Acids Res ; 52(10): 6017-6035, 2024 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-38709902

RESUMEN

Archaeal transcription is carried out by a multi-subunit RNA polymerase (RNAP) that is highly homologous in structure and function to eukaryotic RNAP II. Among the set of basal transcription factors, only Spt5 is found in all domains of life, but Spt5 has been shaped during evolution, which is also reflected in the heterodimerization of Spt5 with Spt4 in Archaea and Eukaryotes. To unravel the mechanistic basis of Spt4/5 function in Archaea, we performed structure-function analyses using the archaeal transcriptional machinery of Pyrococcus furiosus (Pfu). We report single-particle cryo-electron microscopy reconstructions of apo RNAP and the archaeal elongation complex (EC) in the absence and presence of Spt4/5. Surprisingly, Pfu Spt4/5 also binds the RNAP in the absence of nucleic acids in a distinct super-contracted conformation. We show that the RNAP clamp/stalk module exhibits conformational flexibility in the apo state of RNAP and that the enzyme contracts upon EC formation or Spt4/5 engagement. We furthermore identified a contact of the Spt5-NGN domain with the DNA duplex that stabilizes the upstream boundary of the transcription bubble and impacts Spt4/5 activity in vitro. This study, therefore, provides the structural basis for Spt4/5 function in archaeal transcription and reveals a potential role beyond the well-described support of elongation.


Asunto(s)
Proteínas Arqueales , ARN Polimerasas Dirigidas por ADN , Modelos Moleculares , Elongación de la Transcripción Genética , Factores de Elongación Transcripcional , Proteínas Arqueales/química , Proteínas Arqueales/metabolismo , Proteínas Arqueales/genética , Proteínas Cromosómicas no Histona/química , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Microscopía por Crioelectrón , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/química , ARN Polimerasas Dirigidas por ADN/genética , Unión Proteica , Pyrococcus furiosus/enzimología , Pyrococcus furiosus/genética , Factores de Elongación Transcripcional/metabolismo , Factores de Elongación Transcripcional/química , Factores de Elongación Transcripcional/genética
3.
PLoS Genet ; 15(2): e1008006, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30802237

RESUMEN

RNA polymerase I (Pol I) synthesizes ribosomal RNA (rRNA) in all eukaryotes, accounting for the major part of transcriptional activity in proliferating cells. Although basal Pol I transcription factors have been characterized in diverse organisms, the molecular basis of the robust rRNA production in vivo remains largely unknown. In S. cerevisiae, the multifunctional Net1 protein was reported to stimulate Pol I transcription. We found that the Pol I-stimulating function can be attributed to the very C-terminal region (CTR) of Net1. The CTR was required for normal cell growth and Pol I recruitment to rRNA genes in vivo and sufficient to promote Pol I transcription in vitro. Similarity with the acidic tail region of mammalian Pol I transcription factor UBF, which could partly functionally substitute for the CTR, suggests conserved roles for CTR-like domains in Pol I transcription from yeast to human.


Asunto(s)
Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , ARN Polimerasa I/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/crecimiento & desarrollo , Secuencia de Aminoácidos , Proteínas de Ciclo Celular/genética , Secuencia Conservada , Humanos , Proteínas Nucleares/genética , Proteínas del Complejo de Iniciación de Transcripción Pol1/química , Proteínas del Complejo de Iniciación de Transcripción Pol1/genética , Proteínas del Complejo de Iniciación de Transcripción Pol1/metabolismo , ARN Ribosómico/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Eliminación de Secuencia , Transcripción Genética
4.
PLoS Genet ; 15(5): e1008157, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-31136569

RESUMEN

Most transcriptional activity of exponentially growing cells is carried out by the RNA Polymerase I (Pol I), which produces a ribosomal RNA (rRNA) precursor. In budding yeast, Pol I is a multimeric enzyme with 14 subunits. Among them, Rpa49 forms with Rpa34 a Pol I-specific heterodimer (homologous to PAF53/CAST heterodimer in human Pol I), which might be responsible for the specific functions of the Pol I. Previous studies provided insight in the involvement of Rpa49 in initiation, elongation, docking and releasing of Rrn3, an essential Pol I transcription factor. Here, we took advantage of the spontaneous occurrence of extragenic suppressors of the growth defect of the rpa49 null mutant to better understand the activity of Pol I. Combining genetic approaches, biochemical analysis of rRNA synthesis and investigation of the transcription rate at the individual gene scale, we characterized mutated residues of the Pol I as novel extragenic suppressors of the growth defect caused by the absence of Rpa49. When mapped on the Pol I structure, most of these mutations cluster within the jaw-lobe module, at an interface formed by the lobe in Rpa135 and the jaw made up of regions of Rpa190 and Rpa12. In vivo, the suppressor allele RPA135-F301S restores normal rRNA synthesis and increases Pol I density on rDNA genes when Rpa49 is absent. Growth of the Rpa135-F301S mutant is impaired when combined with exosome mutation rrp6Δ and it massively accumulates pre-rRNA. Moreover, Pol I bearing Rpa135-F301S is a hyper-active RNA polymerase in an in vitro tailed-template assay. We conclude that RNA polymerase I can be engineered to produce more rRNA in vivo and in vitro. We propose that the mutated area undergoes a conformational change that supports the DNA insertion into the cleft of the enzyme resulting in a super-active form of Pol I.


Asunto(s)
Proteínas del Complejo de Iniciación de Transcripción Pol1/genética , ARN Polimerasa I/genética , ADN Ribosómico/genética , Proteínas del Complejo de Iniciación de Transcripción Pol1/metabolismo , Precursores del ARN/genética , ARN Ribosómico , Ribosomas/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Factores de Transcripción/genética , Transcripción Genética
5.
J Biol Chem ; 295(15): 4782-4795, 2020 04 10.
Artículo en Inglés | MEDLINE | ID: mdl-32060094

RESUMEN

RNA polymerase I (Pol I) is a highly efficient enzyme specialized in synthesizing most ribosomal RNAs. After nucleosome deposition at each round of rDNA replication, the Pol I transcription machinery has to deal with nucleosomal barriers. It has been suggested that Pol I-associated factors facilitate chromatin transcription, but it is unknown whether Pol I has an intrinsic capacity to transcribe through nucleosomes. Here, we used in vitro transcription assays to study purified WT and mutant Pol I variants from the yeast Saccharomyces cerevisiae and compare their abilities to pass a nucleosomal barrier with those of yeast Pol II and Pol III. Under identical conditions, purified Pol I and Pol III, but not Pol II, could transcribe nucleosomal templates. Pol I mutants lacking either the heterodimeric subunit Rpa34.5/Rpa49 or the C-terminal part of the specific subunit Rpa12.2 showed a lower processivity on naked DNA templates, which was even more reduced in the presence of a nucleosome. Our findings suggest that the lobe-binding subunits Rpa34.5/Rpa49 and Rpa12.2 facilitate passage through nucleosomes, suggesting possible cooperation among these subunits. We discuss the contribution of Pol I-specific subunit domains to efficient Pol I passage through nucleosomes in the context of transcription rate and processivity.


Asunto(s)
Cromatina/metabolismo , Nucleosomas/metabolismo , ARN Polimerasa III/metabolismo , ARN Polimerasa II/metabolismo , ARN Polimerasa I/metabolismo , Saccharomyces cerevisiae/metabolismo , Transcripción Genética , Cromatina/genética , Replicación del ADN , ADN Ribosómico/genética , ADN Ribosómico/metabolismo , Nucleosomas/genética , Regiones Promotoras Genéticas , Unión Proteica , Subunidades de Proteína/metabolismo , ARN Polimerasa I/química , ARN Polimerasa I/genética , ARN Polimerasa II/química , ARN Polimerasa II/genética , ARN Polimerasa III/química , ARN Polimerasa III/genética , Ribosomas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo
6.
Methods Mol Biol ; 2533: 71-80, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35796983

RESUMEN

Technical advances have pushed the resolution limit of single-particle cryo-electron microscopy (cryo-EM) throughout the past decade and made the technique accessible to a wide range of samples. Among them, multisubunit DNA-dependent RNA polymerases (Pols) are a prominent example. This review aims at briefly summarizing the architecture and structural adaptations of Pol I, highlighting the importance of cryo-electron microscopy in determining the structures of transcription complexes.


Asunto(s)
Eucariontes , ARN Polimerasa I , Microscopía por Crioelectrón/métodos , Células Eucariotas
7.
Methods Mol Biol ; 2533: 81-96, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35796984

RESUMEN

Recent technological progress revealed new prospects of high-resolution structure determination of macromolecular complexes using cryo-electron microscopy (cryo-EM) . In the field of RNA polymerase (Pol) I research, a number of cryo-EM studies contributed to understanding the highly specialized mechanisms underlying the transcription of ribosomal RNA genes . Despite a broad applicability of the cryo-EM method itself, preparation of samples for high-resolution data collection can be challenging. Here, we describe strategies for the purification and stabilization of Pol I complexes, exemplarily considering advantages and disadvantages of the methodology. We further provide an easy-to-implement protocol for the coating of EM-grids with self-made carbon support films. In sum, we present an efficient workflow for cryo-grid preparation and optimization, including early stage cryo-EM screening that can be adapted to a wide range of soluble samples for high-resolution structure determination .


Asunto(s)
ARN Polimerasas Dirigidas por ADN , Microscopía por Crioelectrón/métodos , Sustancias Macromoleculares/química
8.
Methods Mol Biol ; 2533: 39-59, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35796981

RESUMEN

Nuclear eukaryotic RNA polymerases (RNAPs) transcribe a chromatin template in vivo. Since the basic unit of chromatin, the nucleosome, renders the DNA largely inaccessible, RNAPs have to overcome the nucleosomal barrier for efficient RNA synthesis. Gaining mechanistical insights in the transcription of chromatin templates will be essential to understand the complex process of eukaryotic gene expression. In this article we describe the use of defined in vitro transcription systems for comparative analysis of highly purified RNAPs I-III from S. cerevisiae (hereafter called yeast) transcribing in vitro reconstituted nucleosomal templates. We also provide a protocol to study promoter-dependent RNAP I transcription of purified native 35S ribosomal RNA (rRNA) gene chromatin.


Asunto(s)
Nucleosomas , Saccharomyces cerevisiae , Cromatina/genética , Cromatina/metabolismo , Nucleosomas/genética , Nucleosomas/metabolismo , ARN Polimerasa I/genética , ARN Polimerasa I/metabolismo , ARN Polimerasa II/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Moldes Genéticos , Transcripción Genética
9.
Methods Mol Biol ; 2533: 63-70, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35796982

RESUMEN

In archaea and bacteria the major classes of RNAs are synthesized by one DNA-dependent RNA polymerase (RNAP). In contrast, most eukaryotes have three highly specialized RNAPs to transcribe the nuclear genome. RNAP I synthesizes almost exclusively ribosomal (r)RNA, RNAP II synthesizes mRNA as well as many noncoding RNAs involved in RNA processing or RNA silencing pathways and RNAP III synthesizes mainly tRNA and 5S rRNA. This review discusses functional differences of the three nuclear core RNAPs in the yeast S. cerevisiae with a particular focus on RNAP I transcription of nucleolar ribosomal (r)DNA chromatin.


Asunto(s)
ARN Polimerasa I , Proteínas de Saccharomyces cerevisiae , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN/metabolismo , ARN Polimerasa I/metabolismo , ARN Polimerasa II/metabolismo , ARN Polimerasa III/genética , ARN Polimerasa III/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Transcripción Genética
10.
Methods Mol Biol ; 2533: 25-38, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35796980

RESUMEN

In growing eukaryotic cells, nuclear ribosomal (r)RNA synthesis by RNA polymerase (RNAP) I accounts for the vast majority of cellular transcription. This high output is achieved by the presence of multiple copies of rRNA genes in eukaryotic genomes transcribed at a high rate. In contrast to most of the other transcribed genomic loci, actively transcribed rRNA genes are largely devoid of nucleosomes adapting a characteristic "open" chromatin state, whereas a significant fraction of rRNA genes resides in a transcriptionally inactive nucleosomal "closed" chromatin state. Here, we review our current knowledge about the nature of open rRNA gene chromatin and discuss how this state may be established.


Asunto(s)
Cromatina , Eucariontes , Cromatina/genética , ADN Ribosómico/genética , Eucariontes/genética , Eucariontes/metabolismo , Genes de ARNr , ARN Polimerasa I/genética , ARN Polimerasa I/metabolismo , ARN Ribosómico/genética , Transcripción Genética
11.
Life Sci Alliance ; 5(11)2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-36271492

RESUMEN

Transcription of the ribosomal RNA precursor by RNA polymerase (Pol) I is a major determinant of cellular growth, and dysregulation is observed in many cancer types. Here, we present the purification of human Pol I from cells carrying a genomic GFP fusion on the largest subunit allowing the structural and functional analysis of the enzyme across species. In contrast to yeast, human Pol I carries a single-subunit stalk, and in vitro transcription indicates a reduced proofreading activity. Determination of the human Pol I cryo-EM reconstruction in a close-to-native state rationalizes the effects of disease-associated mutations and uncovers an additional domain that is built into the sequence of Pol I subunit RPA1. This "dock II" domain resembles a truncated HMG box incapable of DNA binding which may serve as a downstream transcription factor-binding platform in metazoans. Biochemical analysis, in situ modelling, and ChIP data indicate that Topoisomerase 2a can be recruited to Pol I via the domain and cooperates with the HMG box domain-containing factor UBF. These adaptations of the metazoan Pol I transcription system may allow efficient release of positive DNA supercoils accumulating downstream of the transcription bubble.


Asunto(s)
ARN Polimerasa I , Precursores del ARN , Humanos , Animales , ARN Polimerasa I/genética , ARN Polimerasa I/metabolismo , Saccharomyces cerevisiae/metabolismo , Factores de Transcripción/metabolismo , ADN
12.
PLoS One ; 16(11): e0252497, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34813592

RESUMEN

In yeast and human cells many of the ribosomal proteins (r-proteins) are required for the stabilisation and productive processing of rRNA precursors. Functional coupling of r-protein assembly with the stabilisation and maturation of subunit precursors potentially promotes the production of ribosomes with defined composition. To further decipher mechanisms of such an intrinsic quality control pathway we analysed here the contribution of three yeast large ribosomal subunit r-proteins rpL2 (uL2), rpL25 (uL23) and rpL34 (eL34) for intermediate nuclear subunit folding steps. Structure models obtained from single particle cryo-electron microscopy analyses provided evidence for specific and hierarchic effects on the stable positioning and remodelling of large ribosomal subunit domains. Based on these structural and previous biochemical data we discuss possible mechanisms of r-protein dependent hierarchic domain arrangement and the resulting impact on the stability of misassembled subunits.


Asunto(s)
Proteínas Fúngicas/metabolismo , Precursores del ARN/metabolismo , Proteínas Ribosómicas/metabolismo , Saccharomyces cerevisiae/metabolismo , Pliegue de Proteína , Subunidades Ribosómicas Grandes/metabolismo
13.
Nat Commun ; 11(1): 1206, 2020 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-32139698

RESUMEN

Transcription of the ribosomal RNA precursor by RNA polymerase (Pol) I is a prerequisite for the biosynthesis of ribosomes in eukaryotes. Compared to Pols II and III, the mechanisms underlying promoter recognition, initiation complex formation and DNA melting by Pol I substantially diverge. Here, we report the high-resolution cryo-EM reconstruction of a Pol I early initiation intermediate assembled on a double-stranded promoter scaffold that prevents the establishment of downstream DNA contacts. Our analyses demonstrate how efficient promoter-backbone interaction is achieved by combined re-arrangements of flexible regions in the 'core factor' subunits Rrn7 and Rrn11. Furthermore, structure-function analysis illustrates how destabilization of the melted DNA region correlates with contraction of the polymerase cleft upon transcription activation, thereby combining promoter recruitment with DNA-melting. This suggests that molecular mechanisms and structural features of Pol I initiation have co-evolved to support the efficient melting, initial transcription and promoter clearance required for high-level rRNA synthesis.


Asunto(s)
Regiones Promotoras Genéticas , ARN Polimerasa I/metabolismo , Saccharomyces cerevisiae/genética , Iniciación de la Transcripción Genética , Secuencia de Aminoácidos , ADN/química , ADN/ultraestructura , Modelos Moleculares , Estructura Secundaria de Proteína , Subunidades de Proteína/metabolismo , ARN Polimerasa I/química , ARN Polimerasa I/ultraestructura , Factor de Transcripción TFIIB/metabolismo
14.
Nat Commun ; 11(1): 6409, 2020 12 17.
Artículo en Inglés | MEDLINE | ID: mdl-33335104

RESUMEN

In eukaryotes, RNA Polymerase (Pol) III is specialized for the transcription of tRNAs and other short, untranslated RNAs. Pol III is a determinant of cellular growth and lifespan across eukaryotes. Upregulation of Pol III transcription is observed in cancer and causative Pol III mutations have been described in neurodevelopmental disorders and hypersensitivity to viral infection. Here, we report a cryo-EM reconstruction at 4.0 Å of human Pol III, allowing mapping and rationalization of reported genetic mutations. Mutations causing neurodevelopmental defects cluster in hotspots affecting Pol III stability and/or biogenesis, whereas mutations affecting viral sensing are located in proximity to DNA binding regions, suggesting an impairment of Pol III cytosolic viral DNA-sensing. Integrating x-ray crystallography and SAXS, we also describe the structure of the higher eukaryote specific RPC5 C-terminal extension. Surprisingly, experiments in living cells highlight a role for this module in the assembly and stability of human Pol III.


Asunto(s)
ARN Polimerasa III/química , Microscopía por Crioelectrón , ARN Polimerasas Dirigidas por ADN/genética , Estabilidad de Enzimas , Células HeLa , Humanos , Modelos Moleculares , Mutación , Conformación Proteica , Subunidades de Proteína , ARN Polimerasa III/genética , ARN Polimerasa III/metabolismo , Dispersión del Ángulo Pequeño , Difracción de Rayos X
15.
Methods Mol Biol ; 1455: 99-108, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27576713

RESUMEN

RNA polymerase I (Pol I) activity is crucial to provide cells with sufficient amounts of ribosomal RNA (rRNA). Synthesis of rRNA takes place in the nucleolus, is tightly regulated and is coordinated with synthesis and assembly of ribosomal proteins, finally resulting in the formation of mature ribosomes. Many studies on Pol I mechanisms and regulation in the model organism S. cerevisiae were performed using either complex in vitro systems reconstituted from more or less purified fractions or genetic analyses. While providing many valuable insights these strategies did not always discriminate between direct and indirect effects in transcription initiation and termination, when mutated forms of Pol I subunits or transcription factors were investigated. Therefore, a well-defined minimal system was developed which allows to reconstitute highly efficient promoter-dependent Pol I initiation and termination of transcription. Transcription can be initiated at a minimal promoter only in the presence of recombinant core factor and extensively purified initiation competent Pol I. Addition of recombinant termination factors triggers transcriptional pausing and release of the ternary transcription complex. This minimal system represents a valuable tool to investigate the direct impact of (lethal) mutations in components of the initiation and termination complexes on the mechanism and regulation of rRNA synthesis.


Asunto(s)
ARN Polimerasa I/metabolismo , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Transcripción Genética , Proteínas de Unión al ADN/aislamiento & purificación , Proteínas de Unión al ADN/metabolismo , Técnicas In Vitro , Proteínas del Complejo de Iniciación de Transcripción Pol1/aislamiento & purificación , Proteínas del Complejo de Iniciación de Transcripción Pol1/metabolismo , Regiones Promotoras Genéticas , ARN Ribosómico/genética , Proteínas Recombinantes , Proteínas de Saccharomyces cerevisiae/aislamiento & purificación , Proteínas de Saccharomyces cerevisiae/metabolismo , Moldes Genéticos
16.
Nat Commun ; 7: 12126, 2016 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-27418187

RESUMEN

Eukaryotic RNA polymerase I (Pol I) is specialized in rRNA gene transcription synthesizing up to 60% of cellular RNA. High level rRNA production relies on efficient binding of initiation factors to the rRNA gene promoter and recruitment of Pol I complexes containing initiation factor Rrn3. Here, we determine the cryo-EM structure of the Pol I-Rrn3 complex at 7.5 Å resolution, and compare it with Rrn3-free monomeric and dimeric Pol I. We observe that Rrn3 contacts the Pol I A43/A14 stalk and subunits A190 and AC40, that association re-organizes the Rrn3 interaction interface, thereby preventing Pol I dimerization; and Rrn3-bound and monomeric Pol I differ from the dimeric enzyme in cleft opening, and localization of the A12.2 C-terminus in the active centre. Our findings thus support a dual role for Rrn3 in transcription initiation to stabilize a monomeric initiation competent Pol I and to drive pre-initiation complex formation.


Asunto(s)
Proteínas del Complejo de Iniciación de Transcripción Pol1/metabolismo , ARN Polimerasa I/química , ARN Polimerasa I/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Microscopía por Crioelectrón/métodos , Proteínas del Complejo de Iniciación de Transcripción Pol1/genética , Regiones Promotoras Genéticas , Dominios Proteicos , Multimerización de Proteína , ARN Polimerasa I/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Transcripción Genética
17.
Mol Cell Biol ; 34(20): 3817-27, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25092870

RESUMEN

Different models have been proposed explaining how eukaryotic gene transcription is terminated. Recently, Nsi1, a factor involved in silencing of ribosomal DNA (rDNA), was shown to be required for efficient termination of rDNA transcription by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. Nsi1 contains Myb-like DNA binding domains and associates in vivo near the 3' end of rRNA genes to rDNA, but information about which and how DNA sequences might influence Nsi1-dependent termination is lacking. Here, we show that binding of Nsi1 to a stretch of 11 nucleotides in the correct orientation was sufficient to pause elongating Pol I shortly upstream of the Nsi1 binding site and to release the transcripts in vitro. The same minimal DNA element triggered Nsi1-dependent termination of pre-rRNA synthesis using an in vivo reporter assay. Termination efficiency in the in vivo system could be enhanced by inclusion of specific DNA sequences downstream of the Nsi1 binding site. These data and the finding that Nsi1 blocks efficiently only Pol I-dependent RNA synthesis in an in vitro transcription system improve our understanding of a unique mechanism of transcription termination.


Asunto(s)
ADN de Hongos/metabolismo , Proteínas de Unión al ADN/metabolismo , ARN Polimerasa I/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Terminación de la Transcripción Genética , Secuencia de Bases , Sitios de Unión , ADN de Hongos/genética , Regiones Promotoras Genéticas , Unión Proteica
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA