51
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Scaiola A, Peña C, Weisser M, Böhringer D, Leibundgut M, Klingauf-Nerurkar P, Gerhardy S, Panse VG, Ban N. Structure of a eukaryotic cytoplasmic pre-40S ribosomal subunit. EMBO J 2018; 37:embj.201798499. [PMID: 29459436 DOI: 10.15252/embj.201798499] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/18/2017] [Accepted: 01/10/2018] [Indexed: 11/09/2022] Open
Abstract
Final maturation of eukaryotic ribosomes occurs in the cytoplasm and requires the sequential removal of associated assembly factors and processing of the immature 20S pre-RNA Using cryo-electron microscopy (cryo-EM), we have determined the structure of a yeast cytoplasmic pre-40S particle in complex with Enp1, Ltv1, Rio2, Tsr1, and Pno1 assembly factors poised to initiate final maturation. The structure reveals that the pre-rRNA adopts a highly distorted conformation of its 3' major and 3' minor domains stabilized by the binding of the assembly factors. This observation is consistent with a mechanism that involves concerted release of the assembly factors orchestrated by the folding of the rRNA in the head of the pre-40S subunit during the final stages of maturation. Our results provide a structural framework for the coordination of the final maturation events that drive a pre-40S particle toward the mature form capable of engaging in translation.
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Affiliation(s)
- Alain Scaiola
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Cohue Peña
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Melanie Weisser
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Daniel Böhringer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Marc Leibundgut
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Purnima Klingauf-Nerurkar
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Stefan Gerhardy
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Vikram Govind Panse
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
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52
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Sturm M, Cheng J, Baßler J, Beckmann R, Hurt E. Interdependent action of KH domain proteins Krr1 and Dim2 drive the 40S platform assembly. Nat Commun 2017; 8:2213. [PMID: 29263326 PMCID: PMC5738357 DOI: 10.1038/s41467-017-02199-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 11/12/2017] [Indexed: 12/14/2022] Open
Abstract
Ribosome biogenesis begins in the nucleolus with the formation of 90S pre-ribosomes, from which pre-40S and pre-60S particles arise that subsequently follow separate maturation pathways. Here, we show how structurally related assembly factors, the KH domain proteins Krr1 and Dim2, participate in ribosome assembly. Initially, Dim2 (Pno1) orchestrates an early step in small subunit biogenesis through its binding to a distinct region of the 90S pre-ribosome. This involves Utp1 of the UTP-B module, and Utp14, an activator of the DEAH-box helicase Dhr1 that catalyzes the removal of U3 snoRNP from the 90S. Following this dismantling reaction, the pre-40S subunit emerges, but Dim2 relocates to the pre-40S platform domain, previously occupied in the 90S by the other KH factor Krr1 through its interaction with Rps14 and the UTP-C module. Our findings show how the structurally related Krr1 and Dim2 can control stepwise ribosome assembly during the 90S-to-pre-40S subunit transition. The biogenesis of eukaryotic ribosomes involves the coordinated interplay of a large number of assembly factors. Here, the authors detail how the conserved KH domain-containing assembly factors Dim2 and Krr1 function in ordering key events during ribosome maturation.
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Affiliation(s)
- Miriam Sturm
- Biochemistry Centre, University of Heidelberg, Heidelberg, 69221, Germany
| | - Jingdong Cheng
- Department of Biochemistry, Gene Center, Center for integrated Protein Science - Munich (CiPS-M), Ludwig-Maximillian University, Munich, 81377, Germany
| | - Jochen Baßler
- Biochemistry Centre, University of Heidelberg, Heidelberg, 69221, Germany
| | - Roland Beckmann
- Department of Biochemistry, Gene Center, Center for integrated Protein Science - Munich (CiPS-M), Ludwig-Maximillian University, Munich, 81377, Germany
| | - Ed Hurt
- Biochemistry Centre, University of Heidelberg, Heidelberg, 69221, Germany.
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53
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Montellese C, Montel-Lehry N, Henras AK, Kutay U, Gleizes PE, O'Donohue MF. Poly(A)-specific ribonuclease is a nuclear ribosome biogenesis factor involved in human 18S rRNA maturation. Nucleic Acids Res 2017; 45:6822-6836. [PMID: 28402503 PMCID: PMC5499762 DOI: 10.1093/nar/gkx253] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/03/2017] [Indexed: 01/28/2023] Open
Abstract
The poly-A specific ribonuclease (PARN), initially characterized for its role in mRNA catabolism, supports the processing of different types of non-coding RNAs including telomerase RNA. Mutations in PARN are linked to dyskeratosis congenita and pulmonary fibrosis. Here, we show that PARN is part of the enzymatic machinery that matures the human 18S ribosomal RNA (rRNA). Consistent with its nucleolar steady-state localization, PARN is required for 40S ribosomal subunit production and co-purifies with 40S subunit precursors. Depletion of PARN or expression of a catalytically-compromised PARN mutant results in accumulation of 3΄ extended 18S rRNA precursors. Analysis of these processing intermediates reveals a defect in 3΄ to 5΄ trimming of the internal transcribed spacer 1 (ITS1) region, subsequent to endonucleolytic cleavage at site E. Consistent with a function of PARN in exonucleolytic trimming of 18S-E pre-rRNA, recombinant PARN can process the corresponding ITS1 RNA fragment in vitro. Trimming of 18S-E pre-rRNA by PARN occurs in the nucleus, upstream of the final endonucleolytic cleavage by the endonuclease NOB1 in the cytoplasm. These results identify PARN as a new component of the ribosome biogenesis machinery in human cells. Defects in ribosome biogenesis could therefore underlie the pathologies linked to mutations in PARN.
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Affiliation(s)
| | - Nathalie Montel-Lehry
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Ulrike Kutay
- Institut für Biochemie, ETH Zurich, Zurich CH-8093, Switzerland
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Marie-Françoise O'Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
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54
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Belhabich-Baumas K, Joret C, Jády BE, Plisson-Chastang C, Shayan R, Klopp C, Henras AK, Henry Y, Mougin A. The Rio1p ATPase hinders premature entry into translation of late pre-40S pre-ribosomal particles. Nucleic Acids Res 2017; 45:10824-10836. [PMID: 28977579 PMCID: PMC5737503 DOI: 10.1093/nar/gkx734] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/17/2017] [Indexed: 12/03/2022] Open
Abstract
Cytoplasmic maturation of precursors to the small ribosomal subunit in yeast requires the intervention of a dozen assembly factors (AFs), the precise roles of which remain elusive. One of these is Rio1p that seems to intervene at a late step of pre-40S particle maturation. We have investigated the role played by Rio1p in the dynamic association and dissociation of AFs with and from pre-40S particles. Our results indicate that Rio1p depletion leads to the stalling of at least 4 AFs (Nob1p, Tsr1p, Pno1p/Dim2p and Fap7p) in 80S-like particles. We conclude that Rio1p is important for the timely release of these factors from 80S-like particles. In addition, we present immunoprecipitation and electron microscopy evidence suggesting that when Rio1p is depleted, a subset of Nob1p-containing pre-40S particles associate with translating polysomes. Using Nob1p as bait, we purified pre-40S particles from cells lacking Rio1p and performed ribosome profiling experiments which suggest that immature 40S subunits can carry out translation elongation. We conclude that lack of Rio1p allows premature entry of pre-40S particles in the translation process and that the presence of Nob1p and of the 18S rRNA 3′ extension in the 20S pre-rRNA is not incompatible with translation elongation.
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Affiliation(s)
- Kamila Belhabich-Baumas
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Clément Joret
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Beáta E Jády
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Ramtin Shayan
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Christophe Klopp
- Unité de Mathématiques et Informatique Appliquées, INRA, 31320 Castanet Tolosan, France
| | - Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Yves Henry
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Annie Mougin
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
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55
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56
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Robert-Paganin J, Halladjian M, Blaud M, Lebaron S, Delbos L, Chardon F, Capeyrou R, Humbert O, Henry Y, Henras AK, Réty S, Leulliot N. Functional link between DEAH/RHA helicase Prp43 activation and ATP base binding. Nucleic Acids Res 2017; 45:1539-1552. [PMID: 28180308 PMCID: PMC5388414 DOI: 10.1093/nar/gkw1233] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 11/17/2016] [Accepted: 11/26/2016] [Indexed: 02/05/2023] Open
Abstract
The DEAH box helicase Prp43 is a bifunctional enzyme from the DEAH/RHA helicase family required both for the maturation of ribosomes and for lariat intron release during splicing. It interacts with G-patch domain containing proteins which activate the enzymatic activity of Prp43 in vitro by an unknown mechanism. In this work, we show that the activation by G-patch domains is linked to the unique nucleotide binding mode of this helicase family. The base of the ATP molecule is stacked between two residues, R159 of the RecA1 domain (R-motif) and F357 of the RecA2 domain (F-motif). Using Prp43 F357A mutants or pyrimidine nucleotides, we show that the lack of stacking of the nucleotide base to the F-motif decouples the NTPase and helicase activities of Prp43. In contrast the R159A mutant (R-motif) showed reduced ATPase and helicase activities. We show that the Prp43 R-motif mutant induces the same phenotype as the absence of the G-patch protein Gno1, strongly suggesting that the processing defects observed in the absence of Gno1 result from a failure to activate the Prp43 helicase. Overall we propose that the stacking between the R- and F-motifs and the nucleotide base is important for the activity and regulation of this helicase family.
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Affiliation(s)
- Julien Robert-Paganin
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Maral Halladjian
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Magali Blaud
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Simon Lebaron
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Lila Delbos
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Florian Chardon
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Régine Capeyrou
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Odile Humbert
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Yves Henry
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Stéphane Réty
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Nicolas Leulliot
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
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57
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Memet I, Doebele C, Sloan KE, Bohnsack MT. The G-patch protein NF-κB-repressing factor mediates the recruitment of the exonuclease XRN2 and activation of the RNA helicase DHX15 in human ribosome biogenesis. Nucleic Acids Res 2017; 45:5359-5374. [PMID: 28115624 PMCID: PMC5435916 DOI: 10.1093/nar/gkx013] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/04/2017] [Indexed: 01/05/2023] Open
Abstract
In eukaryotes, the synthesis of ribosomal subunits, which involves the maturation of the ribosomal (r)RNAs and assembly of ribosomal proteins, requires the co-ordinated action of a plethora of ribosome biogenesis factors. Many of these cofactors remain to be characterized in human cells. Here, we demonstrate that the human G-patch protein NF-κB-repressing factor (NKRF) forms a pre-ribosomal subcomplex with the DEAH-box RNA helicase DHX15 and the 5΄-3΄ exonuclease XRN2. Using UV crosslinking and analysis of cDNA (CRAC), we reveal that NKRF binds to the transcribed spacer regions of the pre-rRNA transcript. Consistent with this, we find that depletion of NKRF, XRN2 or DHX15 impairs an early pre-rRNA cleavage step (A’). The catalytic activity of DHX15, which we demonstrate is stimulated by NKRF functioning as a cofactor, is required for efficient A’ cleavage, suggesting that a structural remodelling event may facilitate processing at this site. In addition, we show that depletion of NKRF or XRN2 also leads to the accumulation of excised pre-rRNA spacer fragments and that NKRF is essential for recruitment of the exonuclease to nucleolar pre-ribosomal complexes. Our findings therefore reveal a novel pre-ribosomal subcomplex that plays distinct roles in the processing of pre-rRNAs and the turnover of excised spacer fragments.
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Affiliation(s)
- Indira Memet
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany
| | - Carmen Doebele
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany
| | - Katherine E Sloan
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany
| | - Markus T Bohnsack
- Institute for Molecular Biology, University Medical Center Göttingen, Georg-August-University, 37073 Göttingen, Germany.,Göttingen Centre for Molecular Biosciences, Georg-August-University, 37073 Göttingen, Germany
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58
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Wells GR, Weichmann F, Sloan KE, Colvin D, Watkins NJ, Schneider C. The ribosome biogenesis factor yUtp23/hUTP23 coordinates key interactions in the yeast and human pre-40S particle and hUTP23 contains an essential PIN domain. Nucleic Acids Res 2017; 45:4796-4809. [PMID: 28082392 PMCID: PMC5416842 DOI: 10.1093/nar/gkw1344] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/22/2016] [Indexed: 11/30/2022] Open
Abstract
Two proteins with PIN endonuclease domains, yUtp24(Fcf1)/hUTP24 and yUtp23/hUTP23 are essential for early pre-ribosomal (r)RNA cleavages at sites A0, A1/1 and A2/2a in yeast and humans. The yUtp24/hUTP24 PIN endonuclease is proposed to cleave at sites A1/1 and A2/2a, but the enzyme cleaving at site A0 is not known. Yeast yUtp23 contains a degenerate, non-essential PIN domain and functions together with the snR30 snoRNA, while human hUTP23 is associated with U17, the human snR30 counterpart. Using in vivo RNA–protein crosslinking and gel shift experiments, we reveal that yUtp23/hUTP23 makes direct contacts with expansion sequence 6 (ES6) in the 18S rRNA sequence and that yUtp23 interacts with the 3΄ half of the snR30 snoRNA. Protein–protein interaction studies further demonstrated that yeast yUtp23 and human hUTP23 directly interact with the H/ACA snoRNP protein yNhp2/hNHP2, the RNA helicase yRok1/hROK1(DDX52), the ribosome biogenesis factor yRrp7/hRRP7 and yUtp24/hUTP24. yUtp23/hUTP23 could therefore be central to the coordinated integration and release of ES6 binding factors and likely plays a pivotal role in remodeling this pre-rRNA region in both yeast and humans. Finally, studies using RNAi-rescue systems in human cells revealed that intact PIN domain and Zinc finger motifs in human hUTP23 are essential for 18S rRNA maturation.
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Affiliation(s)
- Graeme R Wells
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Franziska Weichmann
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Katherine E Sloan
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - David Colvin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Nicholas J Watkins
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Claudia Schneider
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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59
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Kressler D, Hurt E, Baßler J. A Puzzle of Life: Crafting Ribosomal Subunits. Trends Biochem Sci 2017; 42:640-654. [DOI: 10.1016/j.tibs.2017.05.005] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/16/2017] [Accepted: 05/05/2017] [Indexed: 01/24/2023]
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60
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Rps26 directs mRNA-specific translation by recognition of Kozak sequence elements. Nat Struct Mol Biol 2017; 24:700-707. [PMID: 28759050 PMCID: PMC5777333 DOI: 10.1038/nsmb.3442] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 06/27/2017] [Indexed: 11/17/2022]
Abstract
We describe a novel approach to separate two ribosome populations from the same cells and use this method, and RNA-seq, to identify the mRNAs bound to S. cerevisiae ribosomes with and without Rps26, a protein linked to the pathogenesis of Diamond Blackfan Anemia (DBA). These analyses reveal that Rps26 contributes to mRNA-specific translation by recognition of the Kozak sequence in well-translated mRNAs, and that Rps26-deficient ribosomes preferentially translate mRNA from select stress response pathways. Surprisingly, exposure of yeast to these stresses leads to the formation of Rps26-deficient ribosomes and to the increased translation of their target mRNAs. These results describe a novel paradigm, the production of specialized ribosomes, which play physiological roles in augmenting the well-characterized transcriptional stress response with a heretofore unknown translational response, thereby creating a feed forward loop in gene-expression. Moreover, the simultaneous gain-of-function and loss-of-function phenotypes from Rps26-deficient ribosomes can explain the pathogenesis of DBA.
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61
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Tomecki R, Sikorski PJ, Zakrzewska-Placzek M. Comparison of preribosomal RNA processing pathways in yeast, plant and human cells - focus on coordinated action of endo- and exoribonucleases. FEBS Lett 2017; 591:1801-1850. [PMID: 28524231 DOI: 10.1002/1873-3468.12682] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/14/2017] [Accepted: 05/15/2017] [Indexed: 12/17/2022]
Abstract
Proper regulation of ribosome biosynthesis is mandatory for cellular adaptation, growth and proliferation. Ribosome biogenesis is the most energetically demanding cellular process, which requires tight control. Abnormalities in ribosome production have severe consequences, including developmental defects in plants and genetic diseases (ribosomopathies) in humans. One of the processes occurring during eukaryotic ribosome biogenesis is processing of the ribosomal RNA precursor molecule (pre-rRNA), synthesized by RNA polymerase I, into mature rRNAs. It must not only be accurate but must also be precisely coordinated with other phenomena leading to the synthesis of functional ribosomes: RNA modification, RNA folding, assembly with ribosomal proteins and nucleocytoplasmic RNP export. A multitude of ribosome biogenesis factors ensure that these events take place in a correct temporal order. Among them are endo- and exoribonucleases involved in pre-rRNA processing. Here, we thoroughly present a wide spectrum of ribonucleases participating in rRNA maturation, focusing on their biochemical properties, regulatory mechanisms and substrate specificity. We also discuss cooperation between various ribonucleolytic activities in particular stages of pre-rRNA processing, delineating major similarities and differences between three representative groups of eukaryotes: yeast, plants and humans.
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Affiliation(s)
- Rafal Tomecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.,Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Poland
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62
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Murakami K, Nakano K, Shimizu T, Ohto U. The crystal structure of human DEAH-box RNA helicase 15 reveals a domain organization of the mammalian DEAH/RHA family. Acta Crystallogr F Struct Biol Commun 2017; 73:347-355. [PMID: 28580923 PMCID: PMC5458392 DOI: 10.1107/s2053230x17007336] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/17/2017] [Indexed: 12/31/2022] Open
Abstract
DEAH-box RNA helicase 15 (DHX15) plays important roles in RNA metabolism, including in splicing and in ribosome biogenesis. In addition, mammalian DHX15 also mediates the innate immune sensing of viral RNA. However, structural information on this protein is not available, although the structure of the fungal orthologue of this protein, Prp43, has been elucidated. Here, the crystal structure of the ADP-bound form of human DHX15 is reported at a resolution of 2.0 Å. This is the first structure to be revealed of a member of the mammalian DEAH-box RNA helicase (DEAH/RHA) family in a nearly complete form, including the catalytic core consisting of the two N-terminal RecA domains and the C-terminal regulatory domains (CTD). The ADP-bound form of DHX15 displayed a compact structure, in which the RecA domains made extensive contacts with the CTD. Notably, a potential RNA-binding site was found on the surface of a RecA domain with positive electrostatic potential. Almost all structural features were conserved between the fungal Prp43 and the human DHX15, suggesting that they share a fundamentally common mechanism of action and providing a better understanding of the specific mammalian functions of DHX15.
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Affiliation(s)
- Karin Murakami
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kenji Nakano
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Toshiyuki Shimizu
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
| | - Umeharu Ohto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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63
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Senissar M, Manav MC, Brodersen DE. Structural conservation of the PIN domain active site across all domains of life. Protein Sci 2017; 26:1474-1492. [PMID: 28508407 DOI: 10.1002/pro.3193] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 01/26/2023]
Abstract
The PIN (PilT N-terminus) domain is a compact RNA-binding protein domain present in all domains of life. This 120-residue domain consists of a central and parallel β sheet surrounded by α helices, which together organize 4-5 acidic residues in an active site that binds one or more divalent metal ions and in many cases has endoribonuclease activity. In bacteria and archaea, the PIN domain is primarily associated with toxin-antitoxin loci, consisting of a toxin (the PIN domain nuclease) and an antitoxin that inhibits the function of the toxin under normal growth conditions. During nutritional or antibiotic stress, the antitoxin is proteolytically degraded causing activation of the PIN domain toxin leading to a dramatic reprogramming of cellular metabolism to cope with the new situation. In eukaryotes, PIN domains are commonly found as parts of larger proteins and are involved in a range of processes involving RNA cleavage, including ribosomal RNA biogenesis and nonsense-mediated mRNA decay. In this review, we provide a comprehensive overview of the structural characteristics of the PIN domain and compare PIN domains from all domains of life in terms of structure, active site architecture, and activity.
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Affiliation(s)
- M Senissar
- Centre for Bacterial Stress Response and Persistence, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus, 8000, Denmark
| | - M C Manav
- Centre for Bacterial Stress Response and Persistence, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus, 8000, Denmark
| | - D E Brodersen
- Centre for Bacterial Stress Response and Persistence, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus, 8000, Denmark
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64
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Johnson MC, Ghalei H, Doxtader KA, Karbstein K, Stroupe ME. Structural Heterogeneity in Pre-40S Ribosomes. Structure 2017; 25:329-340. [PMID: 28111018 DOI: 10.1016/j.str.2016.12.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/07/2016] [Accepted: 12/21/2016] [Indexed: 11/24/2022]
Abstract
Late-stage 40S ribosome assembly is a highly regulated dynamic process that occurs in the cytoplasm, alongside the full translation machinery. Seven assembly factors (AFs) regulate and facilitate maturation, but the mechanisms through which they work remain undetermined. Here, we present a series of structures of the immature small subunit (pre-40S) determined by three-dimensional (3D) cryoelectron microscopy with 3D sorting to assess the molecule's heterogeneity. These structures demonstrate an extensive structural heterogeneity of interface AFs that likely regulates subunit joining during 40S maturation. We also present structural models for the beak and the platform, two regions where the low resolution of previous studies did not allow for localization of AFs and the rRNA, respectively. These models are supported by biochemical analyses using point variants and suggest that maturation of the 18S 3' end is regulated by dissociation of the AF Dim1 from the subunit interface, consistent with previous biochemical analyses.
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Affiliation(s)
- Matthew C Johnson
- Department of Biological Science, Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA
| | - Homa Ghalei
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katelyn A Doxtader
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katrin Karbstein
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - M Elizabeth Stroupe
- Department of Biological Science, Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA.
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65
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Kala S, Mehta V, Yip CW, Moshiri H, Najafabadi HS, Ma R, Nikpour N, Zimmer SL, Salavati R. The interaction of a Trypanosoma brucei KH-domain protein with a ribonuclease is implicated in ribosome processing. Mol Biochem Parasitol 2016; 211:94-103. [PMID: 27965085 DOI: 10.1016/j.molbiopara.2016.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 12/08/2016] [Accepted: 12/09/2016] [Indexed: 12/24/2022]
Abstract
Ribosomal RNA maturation is best understood in yeast. While substantial efforts have been made to explore parts of these essential pathways in animals, the similarities and uniquenesses of rRNA maturation factors in non-Opisthokonts remain largely unexplored. Eukaryotic ribosome synthesis requires the coordinated activities of hundreds of Assembly Factors (AFs) that transiently associate with pre-ribosomes, many of which are essential. Pno1 and Nob1 are two of six AFs that are required for the cytoplasmic maturation of the 20S pre-rRNA to 18S rRNA in yeast where it has been almost exclusively analyzed. Specifically, Nob1 ribonucleolytic activity generates the mature 3'-end of 18S rRNA. We identified putative Pno1 and Nob1 homologues in the protist Trypanosoma brucei, named TbPNO1 and TbNOB1, and set out to explore their rRNA maturation role further as they are both essential for normal growth. TbPNO1 is a nuclear protein with limited cytosolic localization relative to its yeast homologue. Like in yeast, it interacts directly with TbNOB1, with indications of associations with a larger AF-containing complex. Interestingly, in the absence of TbPNO1, TbNOB1 exhibits non-specific degradation activity on RNA substrates, and its cleavage activity becomes specific only in the presence of TbPNO1, suggesting that TbPNO1-TbNOB1 interaction is essential for regulation and site-specificity of TbNOB1 activity. These results highlight a conserved role of the TbPNO1-TbNOB1 complex in 18S rRNA maturation across eukaryotes; yet reveal a novel role of their interaction in regulation of TbNOB1 enzymatic activity.
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Affiliation(s)
- Smriti Kala
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada
| | - Vaibhav Mehta
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada; Department of Biochemistry, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - Chun Wai Yip
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada
| | - Houtan Moshiri
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada; Department of Biochemistry, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | | | - Ruoyu Ma
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada
| | - Najmeh Nikpour
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada
| | - Sara L Zimmer
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, 55812, USA
| | - Reza Salavati
- Institute of Parasitology, McGill University, Quebec, H9X3V9, Canada; Department of Biochemistry, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada.
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66
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Peña C, Schütz S, Fischer U, Chang Y, Panse VG. Prefabrication of a ribosomal protein subcomplex essential for eukaryotic ribosome formation. eLife 2016; 5. [PMID: 27929371 PMCID: PMC5148605 DOI: 10.7554/elife.21755] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/29/2016] [Indexed: 01/21/2023] Open
Abstract
Spatial clustering of ribosomal proteins (r-proteins) through tertiary interactions is a striking structural feature of the eukaryotic ribosome. However, the functional importance of these intricate inter-connections, and how they are established is currently unclear. Here, we reveal that a conserved ATPase, Fap7, organizes interactions between neighboring r-proteins uS11 and eS26 prior to their delivery to the earliest ribosome precursor, the 90S. In vitro, uS11 only when bound to Fap7 becomes competent to recruit eS26 through tertiary contacts found between these r-proteins on the mature ribosome. Subsequently, Fap7 ATPase activity unloads the uS11:eS26 subcomplex onto its rRNA binding site, and therefore ensures stoichiometric integration of these r-proteins into the 90S. Fap7-depletion in vivo renders uS11 susceptible to proteolysis, and precludes eS26 incorporation into the 90S. Thus, prefabrication of a native-like r-protein subcomplex drives efficient and accurate construction of the eukaryotic ribosome. DOI:http://dx.doi.org/10.7554/eLife.21755.001
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Affiliation(s)
- Cohue Peña
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Sabina Schütz
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Ute Fischer
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Yiming Chang
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Vikram G Panse
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
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67
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Zhang J, McCann KL, Qiu C, Gonzalez LE, Baserga SJ, Hall TMT. Nop9 is a PUF-like protein that prevents premature cleavage to correctly process pre-18S rRNA. Nat Commun 2016; 7:13085. [PMID: 27725644 PMCID: PMC5062617 DOI: 10.1038/ncomms13085] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 09/01/2016] [Indexed: 12/16/2022] Open
Abstract
Numerous factors direct eukaryotic ribosome biogenesis, and defects in a single ribosome assembly factor may be lethal or produce tissue-specific human ribosomopathies. Pre-ribosomal RNAs (pre-rRNAs) must be processed stepwise and at the correct subcellular locations to produce the mature rRNAs. Nop9 is a conserved small ribosomal subunit biogenesis factor, essential in yeast. Here we report a 2.1-Å crystal structure of Nop9 and a small-angle X-ray-scattering model of a Nop9:RNA complex that reveals a ‘C'-shaped fold formed from 11 Pumilio repeats. We show that Nop9 recognizes sequence and structural features of the 20S pre-rRNA near the cleavage site of the nuclease, Nob1. We further demonstrate that Nop9 inhibits Nob1 cleavage, the final processing step to produce mature small ribosomal subunit 18S rRNA. Together, our results suggest that Nop9 is critical for timely cleavage of the 20S pre-rRNA. Moreover, the Nop9 structure exemplifies a new class of Pumilio repeat proteins. Nop9 is a conserved small ribosomal subunit biogenesis factor. Here, Zhang et al. show that Nop9, in complex with RNA, adopts a C-shaped fold formed from 11 Pumillo repeats and propose that Nop9 inhibits premature cleavage of 20S pre-rRNA by inhibiting the Nob1 nuclease.
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Affiliation(s)
- Jun Zhang
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, MD F3-05, Research Triangle Park, North Carolina 27709, USA
| | - Kathleen L McCann
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, MD F3-05, Research Triangle Park, North Carolina 27709, USA.,Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Chen Qiu
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, MD F3-05, Research Triangle Park, North Carolina 27709, USA
| | - Lauren E Gonzalez
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, MD F3-05, Research Triangle Park, North Carolina 27709, USA
| | - Susan J Baserga
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Traci M Tanaka Hall
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, MD F3-05, Research Triangle Park, North Carolina 27709, USA
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68
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Larburu N, Montellese C, O'Donohue MF, Kutay U, Gleizes PE, Plisson-Chastang C. Structure of a human pre-40S particle points to a role for RACK1 in the final steps of 18S rRNA processing. Nucleic Acids Res 2016; 44:8465-78. [PMID: 27530427 PMCID: PMC5041492 DOI: 10.1093/nar/gkw714] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/28/2016] [Accepted: 08/06/2016] [Indexed: 01/24/2023] Open
Abstract
Synthesis of ribosomal subunits in eukaryotes is a complex and tightly regulated process that has been mostly characterized in yeast. The discovery of a growing number of diseases linked to defects in ribosome biogenesis calls for a deeper understanding of these mechanisms and of the specificities of human ribosome maturation. We present the 19 Å resolution cryo-EM reconstruction of a cytoplasmic precursor to the human small ribosomal subunit, purified by using the tagged ribosome biogenesis factor LTV1 as bait. Compared to yeast pre-40S particles, this first three-dimensional structure of a human 40S subunit precursor shows noticeable differences with respect to the position of ribosome biogenesis factors and uncovers the early deposition of the ribosomal protein RACK1 during subunit maturation. Consistently, RACK1 is required for efficient processing of the 18S rRNA 3'-end, which might be related to its role in translation initiation. This first structural analysis of a human pre-ribosomal particle sets the grounds for high-resolution studies of conformational transitions accompanying ribosomal subunit maturation.
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MESH Headings
- Conserved Sequence
- Cryoelectron Microscopy
- Cytoplasm/metabolism
- GTP-Binding Proteins/metabolism
- HEK293 Cells
- HeLa Cells
- Humans
- Models, Molecular
- Neoplasm Proteins/metabolism
- Organelle Biogenesis
- Protein Binding
- RNA Processing, Post-Transcriptional/genetics
- RNA, Ribosomal, 18S/genetics
- Receptors for Activated C Kinase
- Receptors, Cell Surface/metabolism
- Ribosomal Proteins/metabolism
- Ribosome Subunits, Small, Eukaryotic/chemistry
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/ultrastructure
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- Natacha Larburu
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | | | - Marie-Françoise O'Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Ulrike Kutay
- Institut für Biochemie, ETH Zürich, CH-8093 Zurich, Switzerland
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
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69
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Tomecki R, Labno A, Drazkowska K, Cysewski D, Dziembowski A. hUTP24 is essential for processing of the human rRNA precursor at site A1, but not at site A0. RNA Biol 2016; 12:1010-29. [PMID: 26237581 DOI: 10.1080/15476286.2015.1073437] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Production of ribosomes relies on more than 200 accessory factors to ensure the proper sequence of steps and faultless assembly of ribonucleoprotein machinery. Among trans-acting factors are numerous enzymes, including ribonucleases responsible for processing the large rRNA precursor synthesized by RNA polymerase I that encompasses sequences corresponding to mature 18S, 5.8S, and 25/28S rRNA. In humans, the identity of most enzymes responsible for individual processing steps, including endoribonucleases that cleave pre-rRNA at specific sites within regions flanking and separating mature rRNA, remains largely unknown. Here, we investigated the role of hUTP24 in rRNA maturation in human cells. hUTP24 is a human homolog of the Saccharomyces cerevisiae putative PIN domain-containing endoribonuclease Utp24 (yUtp24), which was suggested to participate in the U3 snoRNA-dependent processing of yeast pre-rRNA at sites A0, A1, and A2. We demonstrate that hUTP24 interacts to some extent with proteins homologous to the components of the yeast small subunit (SSU) processome. Moreover, mutation in the putative catalytic site of hUTP24 results in slowed growth of cells and reduced metabolic activity. These effects are associated with a defect in biogenesis of the 40S ribosomal subunit, which results from decreased amounts of 18S rRNA as a consequence of inaccurate pre-rRNA processing at the 5'-end of the 18S rRNA segment (site A1). Interestingly, and in contrast to yeast, site A0 located upstream of A1 is efficiently processed upon UTP24 dysfunction. Finally, hUTP24 inactivation leads to aberrant processing of 18S rRNA 2 nucleotides downstream of the normal A1 cleavage site.
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Affiliation(s)
- Rafal Tomecki
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Anna Labno
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Karolina Drazkowska
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Dominik Cysewski
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Andrzej Dziembowski
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
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70
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Rodríguez-Galán O, García-Gómez JJ, Kressler D, de la Cruz J. Immature large ribosomal subunits containing the 7S pre-rRNA can engage in translation in Saccharomyces cerevisiae. RNA Biol 2016; 12:838-46. [PMID: 26151772 DOI: 10.1080/15476286.2015.1058477] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Evolution has provided eukaryotes with mechanisms that impede immature and/or aberrant ribosomes to engage in translation. These mechanisms basically either prevent the nucleo-cytoplasmic export of these particles or, once in the cytoplasm, the release of associated assembly factors, which interfere with the binding of translation initiation factors and/or the ribosomal subunit joining. We have previously shown that aberrant yeast 40S ribosomal subunits containing the 20S pre-rRNA can engage in translation. In this study, we describe that cells harbouring the dob1-1 allele, encoding a mutated version of the exosome-assisting RNA helicase Mtr4, accumulate otherwise nuclear pre-60S ribosomal particles containing the 7S pre-rRNA in the cytoplasm. Polysome fractionation analyses revealed that these particles are competent for translation and do not induce elongation stalls. This phenomenon is rather specific since most mutations in other exosome components or co-factors, impairing the 3' end processing of the mature 5.8S rRNA, accumulate 7S pre-rRNAs in the nucleus. In addition, we confirm that pre-60S ribosomal particles containing either 5.8S + 30 or 5.8S + 5 pre-rRNAs also engage in translation elongation. We propose that 7S pre-rRNA processing is not strictly required for pre-60S r-particle export and that, upon arrival in the cytoplasm, there is no specific mechanism to prevent translation by premature pre-60S r-particles containing 3' extended forms of mature 5.8S rRNA.
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Affiliation(s)
- Olga Rodríguez-Galán
- a Instituto de Biomedicina de Sevilla ; Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla ; Seville , Spain
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71
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Ma Y, Zhou W, Hong L, Wu Z. Establishment of a Novel Monoclonal Antibody L6 Specific to NOB1. Monoclon Antib Immunodiagn Immunother 2016; 35:100-3. [PMID: 27097067 DOI: 10.1089/mab.2015.0065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
NOB1, a transcription-associated protein, may play important roles in the development of many cancers. In this study, we have efficiently generated one monoclonal antibody (MAb) against NOB1. Enzyme-linked immunosorbent assay (ELISA) and western blot were used to screen the hybridomas. As a result, one MAb named L6 (IgG1) effective in detecting the recombinant and the cellular NOB1 protein was characterized. Using L6, NOB1 was found to be upregulated in gastric cancer cells and tissues compared with normal gastric epithelial cells and nonneoplastic tissues. The expression of NOB1 was also found to be higher in multidrug-resistant gastric cancer cells than that of sensitive cells. This novel MAb will be valuable for investigating the role of NOB1 in carcinogenesis and multidrug resistance of gastric cancer.
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Affiliation(s)
- Yubo Ma
- 1 The First Clinical College, Chongqing Medical University , Chongqing, China
| | - Wei Zhou
- 2 Xijing Hospital of Digestive Diseases, Fourth Military Medical University , Xi'an, Shaanxi Province, China
| | - Liu Hong
- 2 Xijing Hospital of Digestive Diseases, Fourth Military Medical University , Xi'an, Shaanxi Province, China
| | - Zhongjun Wu
- 1 The First Clinical College, Chongqing Medical University , Chongqing, China .,3 Department of Hepatobiliary Surgery, The First Affiliated Hospital, Chongqing Medical University , Chongqing, China
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72
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Wells GR, Weichmann F, Colvin D, Sloan KE, Kudla G, Tollervey D, Watkins NJ, Schneider C. The PIN domain endonuclease Utp24 cleaves pre-ribosomal RNA at two coupled sites in yeast and humans. Nucleic Acids Res 2016; 44:5399-409. [PMID: 27034467 PMCID: PMC4914098 DOI: 10.1093/nar/gkw213] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/18/2016] [Indexed: 11/12/2022] Open
Abstract
During ribosomal RNA (rRNA) maturation, cleavages at defined sites separate the mature rRNAs from spacer regions, but the identities of several enzymes required for 18S rRNA release remain unknown. PilT N-terminus (PIN) domain proteins are frequently endonucleases and the PIN domain protein Utp24 is essential for early cleavages at three pre-rRNA sites in yeast (A0, A1 and A2) and humans (A0, 1 and 2a). In yeast, A1 is cleaved prior to A2 and both cleavages require base-pairing by the U3 snoRNA to the central pseudoknot elements of the 18S rRNA. We found that yeast Utp24 UV-crosslinked in vivo to U3 and the pseudoknot, placing Utp24 close to cleavage at site A1. Yeast and human Utp24 proteins exhibited in vitro endonuclease activity on an RNA substrate containing yeast site A2. Moreover, an intact PIN domain in human UTP24 was required for accurate cleavages at sites 1 and 2a in vivo, whereas mutation of another potential site 2a endonuclease, RCL1, did not affect 18S production. We propose that Utp24 cleaves sites A1/1 and A2/2a in yeast and human cells.
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Affiliation(s)
- Graeme R Wells
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Franziska Weichmann
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - David Colvin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Katherine E Sloan
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Grzegorz Kudla
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Nicholas J Watkins
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Claudia Schneider
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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73
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Mitterer V, Murat G, Réty S, Blaud M, Delbos L, Stanborough T, Bergler H, Leulliot N, Kressler D, Pertschy B. Sequential domain assembly of ribosomal protein S3 drives 40S subunit maturation. Nat Commun 2016; 7:10336. [PMID: 26831757 PMCID: PMC4740875 DOI: 10.1038/ncomms10336] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 11/29/2015] [Indexed: 11/25/2022] Open
Abstract
Eukaryotic ribosomes assemble by association of ribosomal RNA with ribosomal proteins into nuclear precursor particles, which undergo a complex maturation pathway coordinated by non-ribosomal assembly factors. Here, we provide functional insights into how successive structural re-arrangements in ribosomal protein S3 promote maturation of the 40S ribosomal subunit. We show that S3 dimerizes and is imported into the nucleus with its N-domain in a rotated conformation and associated with the chaperone Yar1. Initial assembly of S3 with 40S precursors occurs via its C-domain, while the N-domain protrudes from the 40S surface. Yar1 is replaced by the assembly factor Ltv1, thereby fixing the S3 N-domain in the rotated orientation and preventing its 40S association. Finally, Ltv1 release, triggered by phosphorylation, and flipping of the S3 N-domain into its final position results in the stable integration of S3. Such a stepwise assembly may represent a new paradigm for the incorporation of ribosomal proteins. Ribosome biogenesis involves the hierarchical assembly of several proteins and RNA components. Here the authors describe a mechanism for ribosomal protein S3 incorporation into 40S ribosomal subunits that involves S3 dimerization and stepwise incorporation of two distinct S3 interaction domains coupled to release of ribosomal maturation factors.
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Affiliation(s)
- Valentin Mitterer
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Stéphane Réty
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Magali Blaud
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Lila Delbos
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Tamsyn Stanborough
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Helmut Bergler
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Nicolas Leulliot
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Brigitte Pertschy
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
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74
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Tauchert MJ, Fourmann JB, Christian H, Lührmann R, Ficner R. Structural and functional analysis of the RNA helicase Prp43 from the thermophilic eukaryote Chaetomium thermophilum. Acta Crystallogr F Struct Biol Commun 2016; 72:112-20. [PMID: 26841761 PMCID: PMC4741191 DOI: 10.1107/s2053230x15024498] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 12/20/2015] [Indexed: 02/03/2023] Open
Abstract
RNA helicases are indispensable for all organisms in each domain of life and have implications in numerous cellular processes. The DEAH-box RNA helicase Prp43 is involved in pre-mRNA splicing as well as rRNA maturation. Here, the crystal structure of Chaetomium thermophilum Prp43 at 2.9 Å resolution is revealed. Furthermore, it is demonstrated that Prp43 from C. thermophilum is capable of functionally replacing its orthologue from Saccharomyces cerevisiae in spliceosomal disassembly assays.
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Affiliation(s)
- Marcel J. Tauchert
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Jean-Baptiste Fourmann
- Department of Cellular Biochemistry, Max Planck Institute of Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Henning Christian
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute of Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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75
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Heininger AU, Hackert P, Andreou AZ, Boon KL, Memet I, Prior M, Clancy A, Schmidt B, Urlaub H, Schleiff E, Sloan KE, Deckers M, Lührmann R, Enderlein J, Klostermeier D, Rehling P, Bohnsack MT. Protein cofactor competition regulates the action of a multifunctional RNA helicase in different pathways. RNA Biol 2016; 13:320-30. [PMID: 26821976 PMCID: PMC4829300 DOI: 10.1080/15476286.2016.1142038] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A rapidly increasing number of RNA helicases are implicated in several distinct cellular processes, however, the modes of regulation of multifunctional RNA helicases and their recruitment to different target complexes have remained unknown. Here, we show that the distribution of the multifunctional DEAH-box RNA helicase Prp43 between its diverse cellular functions can be regulated by the interplay of its G-patch protein cofactors. We identify the orphan G-patch protein Cmg1 (YLR271W) as a novel cofactor of Prp43 and show that it stimulates the RNA binding and ATPase activity of the helicase. Interestingly, Cmg1 localizes to the cytoplasm and to the intermembrane space of mitochondria and its overexpression promotes apoptosis. Furthermore, our data reveal that different G-patch protein cofactors compete for interaction with Prp43. Changes in the expression levels of Prp43-interacting G-patch proteins modulate the cellular localization of Prp43 and G-patch protein overexpression causes accumulation of the helicase in the cytoplasm or nucleoplasm. Overexpression of several G-patch proteins also leads to defects in ribosome biogenesis that are consistent with withdrawal of the helicase from this pathway. Together, these findings suggest that the availability of cofactors and the sequestering of the helicase are means to regulate the activity of multifunctional RNA helicases and their distribution between different cellular processes.
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Affiliation(s)
- Annika U Heininger
- a Institute for Molecular Biology, Georg-August University , Goettingen , Germany
| | - Philipp Hackert
- a Institute for Molecular Biology, Georg-August University , Goettingen , Germany
| | - Alexandra Z Andreou
- b Institute for Physical Chemistry, University of Muenster , Muenster , Germany
| | - Kum-Loong Boon
- c Max-Planck-Institute for Biophysical Chemistry , Goettingen , Germany
| | - Indira Memet
- a Institute for Molecular Biology, Georg-August University , Goettingen , Germany
| | - Mira Prior
- d III. Institute of Physics-Biophysics, Georg-August University , Goettingen , Germany
| | - Anne Clancy
- a Institute for Molecular Biology, Georg-August University , Goettingen , Germany
| | - Bernhard Schmidt
- e Institute of Cellular Biochemistry, Georg-August University , Goettingen , Germany
| | - Henning Urlaub
- c Max-Planck-Institute for Biophysical Chemistry , Goettingen , Germany
| | - Enrico Schleiff
- f Institute for Molecular Biosciences, Goethe University , Frankfurt , Germany
| | - Katherine E Sloan
- a Institute for Molecular Biology, Georg-August University , Goettingen , Germany
| | - Markus Deckers
- e Institute of Cellular Biochemistry, Georg-August University , Goettingen , Germany
| | - Reinhard Lührmann
- c Max-Planck-Institute for Biophysical Chemistry , Goettingen , Germany
| | - Jörg Enderlein
- d III. Institute of Physics-Biophysics, Georg-August University , Goettingen , Germany
| | - Dagmar Klostermeier
- b Institute for Physical Chemistry, University of Muenster , Muenster , Germany
| | - Peter Rehling
- c Max-Planck-Institute for Biophysical Chemistry , Goettingen , Germany.,e Institute of Cellular Biochemistry, Georg-August University , Goettingen , Germany.,g Goettingen Center for Molecular Biosciences, Georg-August-University , Goettingen , Germany
| | - Markus T Bohnsack
- a Institute for Molecular Biology, Georg-August University , Goettingen , Germany.,g Goettingen Center for Molecular Biosciences, Georg-August-University , Goettingen , Germany
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76
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Stoll B, Binder S. Two NYN domain containing putative nucleases are involved in transcript maturation in Arabidopsis mitochondria. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 85:278-288. [PMID: 26711866 DOI: 10.1111/tpj.13111] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/11/2015] [Accepted: 12/14/2015] [Indexed: 06/05/2023]
Abstract
Plant mitochondrial transcripts frequently undergo maturation processes at their 5' ends. This almost completely enigmatic process requires the function of several proteins such as RNA processing factors, which are selectively involved in distinct 5' processing events. As RNA processing factors represent pentatricopeptide repeat proteins without apparent enzymatic function, it is hypothesized that a ribonuclease, most likely with endonucleolytic activity is involved in the 5' end maturation. We have now applied a reverse genetic approach to analyze the role of two potential mitochondrial nucleases, MNU1 and MNU2, in Arabidopsis thaliana. Both proteins contain several RNA-binding domains and NYN domains found in other endonucleases. A thorough analysis of various mitochondrial transcripts in MNU1 and MNU2 mutants revealed aberrant transcript pattern characterized by a decrease in mature RNA species often accompanied by an accumulation of larger, 5' extended precursor molecules. In addition, severely reduced amounts of nad9 mRNAs in the rpf2-1/mnu2-1 double mutant indicate a corporate function of RNA processing factor 2 and MNU2 in the maturation of these transcripts. However, the dramatic reduction of the nad9 mRNA is not reflected by the level of the corresponding Nad9 protein, which is found to be only moderately lowered. Collectively, our analysis strongly suggests a function of MNU1 and MNU2 in 5' processing of plant mitochondrial transcripts.
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Affiliation(s)
- Birgit Stoll
- Institut Molekulare Botanik, Universität Ulm, Ulm, D-89069, Germany
| | - Stefan Binder
- Institut Molekulare Botanik, Universität Ulm, Ulm, D-89069, Germany
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77
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Barrio-Garcia C, Thoms M, Flemming D, Kater L, Berninghausen O, Baßler J, Beckmann R, Hurt E. Architecture of the Rix1-Rea1 checkpoint machinery during pre-60S-ribosome remodeling. Nat Struct Mol Biol 2015; 23:37-44. [PMID: 26619264 DOI: 10.1038/nsmb.3132] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 10/30/2015] [Indexed: 01/01/2023]
Abstract
Ribosome synthesis is catalyzed by ∼200 assembly factors, which facilitate efficient production of mature ribosomes. Here, we determined the cryo-EM structure of a Saccharomyces cerevisiae nucleoplasmic pre-60S particle containing the dynein-related 550-kDa Rea1 AAA(+) ATPase and the Rix1 subcomplex. This particle differs from its preceding state, the early Arx1 particle, by two massive structural rearrangements: an ∼180° rotation of the 5S ribonucleoprotein complex and the central protuberance (CP) rRNA helices, and the removal of the 'foot' structure from the 3' end of the 5.8S rRNA. Progression from the Arx1 to the Rix1 particle was blocked by mutational perturbation of the Rix1-Rea1 interaction but not by a dominant-lethal Rea1 AAA(+) ATPase-ring mutant. After remodeling, the Rix1 subcomplex and Rea1 become suitably positioned to sense correct structural maturation of the CP, which allows unidirectional progression toward mature ribosomes.
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Affiliation(s)
| | - Matthias Thoms
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Dirk Flemming
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Lukas Kater
- Gene Center, University of Munich, Munich, Germany
| | | | - Jochen Baßler
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | | | - Ed Hurt
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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78
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Thoms M, Thomson E, Baßler J, Gnädig M, Griesel S, Hurt E. The Exosome Is Recruited to RNA Substrates through Specific Adaptor Proteins. Cell 2015; 162:1029-38. [PMID: 26317469 DOI: 10.1016/j.cell.2015.07.060] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 05/18/2015] [Accepted: 07/02/2015] [Indexed: 12/15/2022]
Abstract
The exosome regulates the processing, degradation, and surveillance of a plethora of RNA species. However, little is known about how the exosome recognizes and is recruited to its diverse substrates. We report the identification of adaptor proteins that recruit the exosome-associated helicase, Mtr4, to unique RNA substrates. Nop53, the yeast homolog of the tumor suppressor PICT1, targets Mtr4 to pre-ribosomal particles for exosome-mediated processing, while a second adaptor Utp18 recruits Mtr4 to cleaved rRNA fragments destined for degradation by the exosome. Both Nop53 and Utp18 contain the same consensus motif, through which they dock to the "arch" domain of Mtr4 and target it to specific substrates. These findings show that the exosome employs a general mechanism of recruitment to defined substrates and that this process is regulated through adaptor proteins.
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Affiliation(s)
- Matthias Thoms
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany
| | - Emma Thomson
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany
| | - Jochen Baßler
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany
| | - Marén Gnädig
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany
| | - Sabine Griesel
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany.
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79
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He Y, Andersen GR, Nielsen KH. The function and architecture of DEAH/RHA helicases. Biomol Concepts 2015; 2:315-26. [PMID: 25962039 DOI: 10.1515/bmc.2011.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 05/24/2011] [Indexed: 12/11/2022] Open
Abstract
Helicases are ubiquitous enzymes that participate in every aspect of nucleic acid metabolism. The DEAH/RHA family of helicases are involved in a variety of cellular processes including transcriptional and translational regulation, pre-mRNA splicing, pre-rRNA processing, mRNA export and decay, in addition to the innate immune response. Recently, the first crystal structures of a DEAH/RHA helicase unveiled the unique structural features of this helicase family. These structures furthermore illuminate the molecular mechanism of these proteins and provide a framework for analysis of their interaction with nucleic acids, regulatory proteins and large macromolecular complexes.
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80
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Pausch P, Singh U, Ahmed YL, Pillet B, Murat G, Altegoer F, Stier G, Thoms M, Hurt E, Sinning I, Bange G, Kressler D. Co-translational capturing of nascent ribosomal proteins by their dedicated chaperones. Nat Commun 2015; 6:7494. [PMID: 26112308 PMCID: PMC4491177 DOI: 10.1038/ncomms8494] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/14/2015] [Indexed: 12/11/2022] Open
Abstract
Exponentially growing yeast cells produce every minute >160,000 ribosomal proteins. Owing to their difficult physicochemical properties, the synthesis of assembly-competent ribosomal proteins represents a major challenge. Recent evidence highlights that dedicated chaperone proteins recognize the N-terminal regions of ribosomal proteins and promote their soluble expression and delivery to the assembly site. Here we explore the intuitive possibility that ribosomal proteins are captured by dedicated chaperones in a co-translational manner. Affinity purification of four chaperones (Rrb1, Syo1, Sqt1 and Yar1) selectively enriched the mRNAs encoding their specific ribosomal protein clients (Rpl3, Rpl5, Rpl10 and Rps3). X-ray crystallography reveals how the N-terminal, rRNA-binding residues of Rpl10 are shielded by Sqt1's WD-repeat β-propeller, providing mechanistic insight into the incorporation of Rpl10 into pre-60S subunits. Co-translational capturing of nascent ribosomal proteins by dedicated chaperones constitutes an elegant mechanism to prevent unspecific interactions and aggregation of ribosomal proteins on their road to incorporation. The synthesis of ribosomes requires the orderly assembly of many proteins and large RNA molecules, a process that involves several assembly factors. Here the authors show that dedicated chaperones capture the N termini of specific nascent ribosomal proteins to promote folding and assembly into maturing ribosomes.
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Affiliation(s)
- Patrick Pausch
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße, Marburg D-35043, Germany
| | - Ujjwala Singh
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
| | - Yasar Luqman Ahmed
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Benjamin Pillet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
| | - Florian Altegoer
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße, Marburg D-35043, Germany
| | - Gunter Stier
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Matthias Thoms
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Gert Bange
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße, Marburg D-35043, Germany
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
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81
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Limited portability of G-patch domains in regulators of the Prp43 RNA helicase required for pre-mRNA splicing and ribosomal RNA maturation in Saccharomyces cerevisiae. Genetics 2015; 200:135-47. [PMID: 25808954 DOI: 10.1534/genetics.115.176461] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/22/2015] [Indexed: 12/16/2022] Open
Abstract
The Prp43 DExD/H-box protein is required for progression of the biochemically distinct pre-messenger RNA and ribosomal RNA (rRNA) maturation pathways. In Saccharomyces cerevisiae, the Spp382/Ntr1, Sqs1/Pfa1, and Pxr1/Gno1 proteins are implicated as cofactors necessary for Prp43 helicase activation during spliceosome dissociation (Spp382) and rRNA processing (Sqs1 and Pxr1). While otherwise dissimilar in primary sequence, these Prp43-binding proteins each contain a short glycine-rich G-patch motif required for function and thought to act in protein or nucleic acid recognition. Here yeast two-hybrid, domain-swap, and site-directed mutagenesis approaches are used to investigate G-patch domain activity and portability. Our results reveal that the Spp382, Sqs1, and Pxr1 G-patches differ in Prp43 two-hybrid response and in the ability to reconstitute the Spp382 and Pxr1 RNA processing factors. G-patch protein reconstitution did not correlate with the apparent strength of the Prp43 two-hybrid response, suggesting that this domain has function beyond that of a Prp43 tether. Indeed, while critical for Pxr1 activity, the Pxr1 G-patch appears to contribute little to the yeast two-hybrid interaction. Conversely, deletion of the primary Prp43 binding site within Pxr1 (amino acids 102-149) does not impede rRNA processing but affects small nucleolar RNA (snoRNA) biogenesis, resulting in the accumulation of slightly extended forms of select snoRNAs, a phenotype unexpectedly shared by the prp43 loss-of-function mutant. These and related observations reveal differences in how the Spp382, Sqs1, and Pxr1 proteins interact with Prp43 and provide evidence linking G-patch identity with pathway-specific DExD/H-box helicase activity.
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82
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Haag S, Kretschmer J, Bohnsack MT. WBSCR22/Merm1 is required for late nuclear pre-ribosomal RNA processing and mediates N7-methylation of G1639 in human 18S rRNA. RNA (NEW YORK, N.Y.) 2015; 21:180-7. [PMID: 25525153 PMCID: PMC4338346 DOI: 10.1261/rna.047910.114] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/11/2014] [Indexed: 05/10/2023]
Abstract
Ribosomal (r)RNAs are extensively modified during ribosome synthesis and their modification is required for the fidelity and efficiency of translation. Besides numerous small nucleolar RNA-guided 2'-O methylations and pseudouridinylations, a number of individual RNA methyltransferases are involved in rRNA modification. WBSCR22/Merm1, which is affected in Williams-Beuren syndrome and has been implicated in tumorigenesis and metastasis formation, was recently shown to be involved in ribosome synthesis, but its molecular functions have remained elusive. Here we show that depletion of WBSCR22 leads to nuclear accumulation of 3'-extended 18SE pre-rRNA intermediates resulting in impaired 18S rRNA maturation. We map the 3' ends of the 18SE pre-rRNA intermediates accumulating after depletion of WBSCR22 and in control cells using 3'-RACE and deep sequencing. Furthermore, we demonstrate that WBSCR22 is required for N(7)-methylation of G1639 in human 18S rRNA in vivo. Interestingly, the catalytic activity of WBSCR22 is not required for 18S pre-rRNA processing, suggesting that the key role of WBSCR22 in 40S subunit biogenesis is independent of its function as an RNA methyltransferase.
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Affiliation(s)
- Sara Haag
- Centre for Biochemistry and Molecular Cell Biology, Georg-August-University, 37073 Göttingen, Germany
| | - Jens Kretschmer
- Centre for Biochemistry and Molecular Cell Biology, Georg-August-University, 37073 Göttingen, Germany
| | - Markus T Bohnsack
- Centre for Biochemistry and Molecular Cell Biology, Georg-August-University, 37073 Göttingen, Germany Göttingen Centre for Molecular Biosciences, Georg-August-University, 37073 Göttingen, Germany
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83
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Regulation of DEAH/RHA helicases by G-patch proteins. BIOMED RESEARCH INTERNATIONAL 2015; 2015:931857. [PMID: 25692149 PMCID: PMC4322301 DOI: 10.1155/2015/931857] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 10/19/2014] [Accepted: 10/24/2014] [Indexed: 11/20/2022]
Abstract
RNA helicases from the DEAH/RHA family are present in all the processes of RNA metabolism. The function of two helicases from this family, Prp2 and Prp43, is regulated by protein partners containing a G-patch domain. The G-patch is a glycine-rich domain discovered by sequence alignment, involved in protein-protein and protein-nucleic acid interaction. Although it has been shown to stimulate the helicase's enzymatic activities, the precise role of the G-patch domain remains unclear. The role of G-patch proteins in the regulation of Prp43 activity has been studied in the two biological processes in which it is involved: splicing and ribosome biogenesis. Depending on the pathway, the activity of Prp43 is modulated by different G-patch proteins. A particular feature of the structure of DEAH/RHA helicases revealed by the Prp43 structure is the OB-fold domain in C-terminal part. The OB-fold has been shown to be a platform responsible for the interaction with G-patch proteins and RNA. Though there is still no structural data on the G-patch domain, in the current model, the interaction between the helicase, the G-patch protein, and RNA leads to a cooperative binding of RNA and conformational changes of the helicase.
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84
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Nerurkar P, Altvater M, Gerhardy S, Schütz S, Fischer U, Weirich C, Panse VG. Eukaryotic Ribosome Assembly and Nuclear Export. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 319:107-40. [DOI: 10.1016/bs.ircmb.2015.07.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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85
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Moriggi G, Nieto B, Dosil M. Rrp12 and the Exportin Crm1 participate in late assembly events in the nucleolus during 40S ribosomal subunit biogenesis. PLoS Genet 2014; 10:e1004836. [PMID: 25474739 PMCID: PMC4256259 DOI: 10.1371/journal.pgen.1004836] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 10/17/2014] [Indexed: 11/20/2022] Open
Abstract
During the biogenesis of small ribosomal subunits in eukaryotes, the pre-40S particles formed in the nucleolus are rapidly transported to the cytoplasm. The mechanisms underlying the nuclear export of these particles and its coordination with other biogenesis steps are mostly unknown. Here we show that yeast Rrp12 is required for the exit of pre-40S particles to the cytoplasm and for proper maturation dynamics of upstream 90S pre-ribosomes. Due to this, in vivo elimination of Rrp12 leads to an accumulation of nucleoplasmic 90S to pre-40S transitional particles, abnormal 35S pre-rRNA processing, delayed elimination of processing byproducts, and no export of intermediate pre-40S complexes. The exportin Crm1 is also required for the same pre-ribosome maturation events that involve Rrp12. Thus, in addition to their implication in nuclear export, Rrp12 and Crm1 participate in earlier biosynthetic steps that take place in the nucleolus. Our results indicate that, in the 40S subunit synthesis pathway, the completion of early pre-40S particle assembly, the initiation of byproduct degradation and the priming for nuclear export occur in an integrated manner in late 90S pre-ribosomes.
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Affiliation(s)
- Giulia Moriggi
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer (IBMCC), CSIC-University of Salamanca, Salamanca, Spain
| | - Blanca Nieto
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer (IBMCC), CSIC-University of Salamanca, Salamanca, Spain
| | - Mercedes Dosil
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer (IBMCC), CSIC-University of Salamanca, Salamanca, Spain
- Departamento de Bioquímica y Biología Molecular, University of Salamanca, Salamanca, Spain
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86
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Jia JW, Liu AQ, Wang Y, Zhao F, Jiao LL, Tan J. Evaluation of NIN/RPN12 binding protein inhibits proliferation and growth in human renal cancer cells. Tumour Biol 2014; 36:1803-10. [PMID: 25420906 DOI: 10.1007/s13277-014-2783-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 10/27/2014] [Indexed: 12/22/2022] Open
Abstract
The targeted delivery of small interfering RNA (siRNA) to specific tumor tissues and tumor cells remains as one of the key challenges in the development of RNA interference as a therapeutic application. The ribosome assembly factor NIN/RPN12 binding protein (NOB1) has been suggested to be essential for processing of the 20S pre-rRNA to the mature 18S rRNA, and is also reported to participate in proteasome biogenesis. However, it is unclear whether NOB1 is involved in tumor cells growth. The aim of this study was to determine whether the suppression of lentivirus mediated NOB1 siRNA inhibits the growth of human clean cell carcinoma (ccRCC) cells, further focused on NOB1 as a possible therapeutic target for renal cell carcinoma treatment. NOB1 deletion that caused significant decline in cell proliferation was observed in both 786-O and ACHN cell lines as investigated by MTT assay. Further, the number and size of the colonies formed were also significantly reduced in the absence of NOB1. Moreover, NOB1 gene knockdown arrested the cell cycle and inhibited cell cycle-related protein expression. The Kaplan-Meier survival curves revealed that low NOB1 expression was associated with poor prognosis in ccRCC patients. Collectively, these results indicate that NOB1 plays an essential role in renal cell cancer cell proliferation, and its gene expression could be a therapeutic target.
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Affiliation(s)
- Jian-wei Jia
- Department of Oncology, The Third Affiliated Hospital of Xinxiang Medical University, Xinxiang, 453003, China
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87
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Henras AK, Plisson-Chastang C, O'Donohue MF, Chakraborty A, Gleizes PE. An overview of pre-ribosomal RNA processing in eukaryotes. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:225-42. [PMID: 25346433 PMCID: PMC4361047 DOI: 10.1002/wrna.1269] [Citation(s) in RCA: 391] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/04/2014] [Accepted: 08/29/2014] [Indexed: 12/23/2022]
Abstract
Ribosomal RNAs are the most abundant and universal noncoding RNAs in living organisms. In eukaryotes, three of the four ribosomal RNAs forming the 40S and 60S subunits are borne by a long polycistronic pre-ribosomal RNA. A complex sequence of processing steps is required to gradually release the mature RNAs from this precursor, concomitant with the assembly of the 79 ribosomal proteins. A large set of trans-acting factors chaperone this process, including small nucleolar ribonucleoparticles. While yeast has been the gold standard for studying the molecular basis of this process, recent technical advances have allowed to further define the mechanisms of ribosome biogenesis in animals and plants. This renewed interest for a long-lasting question has been fueled by the association of several genetic diseases with mutations in genes encoding both ribosomal proteins and ribosome biogenesis factors, and by the perspective of new anticancer treatments targeting the mechanisms of ribosome synthesis. A consensus scheme of pre-ribosomal RNA maturation is emerging from studies in various kinds of eukaryotic organisms. However, major differences between mammalian and yeast pre-ribosomal RNA processing have recently come to light. WIREs RNA 2015, 6:225–242. doi: 10.1002/wrna.1269
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Affiliation(s)
- Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Université de Toulouse-Paul Sabatier CNRS, UMR 5099, Toulouse, France
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88
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Fernández-Pevida A, Kressler D, de la Cruz J. Processing of preribosomal RNA in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:191-209. [PMID: 25327757 DOI: 10.1002/wrna.1267] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/02/2014] [Accepted: 09/02/2014] [Indexed: 11/07/2022]
Abstract
Most, if not all RNAs, are transcribed as precursors that require processing to gain functionality. Ribosomal RNAs (rRNA) from all organisms undergo both exo- and endonucleolytic processing. Also, in all organisms, rRNA processing occurs inside large preribosomal particles and is coupled to nucleotide modification, folding of the precursor rRNA (pre-rRNA), and assembly of the ribosomal proteins (r-proteins). In this review, we focus on the processing pathway of pre-rRNAs of cytoplasmic ribosomes in the yeast Saccharomyces cerevisiae, without doubt, the organism where this pathway is best characterized. We summarize the current understanding of the rRNA maturation process, particularly focusing on the pre-rRNA processing sites, the enzymes responsible for the cleavage or trimming reactions and the different mechanisms that monitor and regulate the pathway. Strikingly, the overall order of the various processing steps is reasonably well conserved in eukaryotes, perhaps reflecting common principles for orchestrating the concomitant events of pre-rRNA processing and ribosome assembly.
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Affiliation(s)
- Antonio Fernández-Pevida
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain; Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
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89
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Turowski TW, Lebaron S, Zhang E, Peil L, Dudnakova T, Petfalski E, Granneman S, Rappsilber J, Tollervey D. Rio1 mediates ATP-dependent final maturation of 40S ribosomal subunits. Nucleic Acids Res 2014; 42:12189-99. [PMID: 25294836 PMCID: PMC4231747 DOI: 10.1093/nar/gku878] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During the last step in 40S ribosome subunit biogenesis, the PIN-domain endonuclease Nob1 cleaves the 20S pre-rRNA at site D, to form the mature 18S rRNAs. Here we report that cleavage occurs in particles that have largely been stripped of previously characterized pre-40S components, but retain the endonuclease Nob1, its binding partner Pno1 (Dim2) and the atypical ATPase Rio1. Within the Rio1-associated pre-40S particles, in vitro pre-rRNA cleavage was strongly stimulated by ATP and required nucleotide binding by Rio1. In vivo binding sites for Rio1, Pno1 and Nob1 were mapped by UV cross-linking in actively growing cells. Nob1 and Pno1 bind overlapping regions within the internal transcribed spacer 1, and both bind directly over cleavage site D. Binding sites for Rio1 were within the core of the 18S rRNA, overlapping tRNA interaction sites and distinct from the related kinase Rio2. Site D cleavage occurs within pre-40S-60S complexes and Rio1-associated particles efficiently assemble into these complexes, whereas Pno1 appeared to be depleted relative to Nob1. We speculate that Rio1-mediated dissociation of Pno1 from cleavage site D is the trigger for final 18S rRNA maturation.
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Affiliation(s)
- Tomasz W Turowski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Simon Lebaron
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Elodie Zhang
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Lauri Peil
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Tatiana Dudnakova
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Elisabeth Petfalski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Sander Granneman
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
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90
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Schütz S, Fischer U, Altvater M, Nerurkar P, Peña C, Gerber M, Chang Y, Caesar S, Schubert OT, Schlenstedt G, Panse VG. A RanGTP-independent mechanism allows ribosomal protein nuclear import for ribosome assembly. eLife 2014; 3:e03473. [PMID: 25144938 PMCID: PMC4161973 DOI: 10.7554/elife.03473] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Within a single generation time a growing yeast cell imports ∼14 million ribosomal proteins (r-proteins) into the nucleus for ribosome production. After import, it is unclear how these intrinsically unstable and aggregation-prone proteins are targeted to the ribosome assembly site in the nucleolus. Here, we report the discovery of a conserved nuclear carrier Tsr2 that coordinates transfer of the r-protein eS26 to the earliest assembling pre-ribosome, the 90S. In vitro studies revealed that Tsr2 efficiently dissociates importin:eS26 complexes via an atypical RanGTP-independent mechanism that terminates the import process. Subsequently, Tsr2 binds the released eS26, shields it from proteolysis, and ensures its safe delivery to the 90S pre-ribosome. We anticipate similar carriers—termed here escortins—to securely connect the nuclear import machinery with pathways that deposit r-proteins onto developing pre-ribosomal particles. DOI:http://dx.doi.org/10.7554/eLife.03473.001 The production of a protein in a cell starts with a region of DNA being transcribed to produce a molecule of messenger RNA. A large molecular machine called ribosome then reads the information in the messenger RNA molecule to produce a protein. Ribosomes themselves are made of RNA and several different proteins called r-proteins. The construction of a ribosome starts with the assembly of a pre-ribosome inside the cell nucleus, and the ribosome is completed in the cytosol of the cell. A yeast cell will divide about 30 times during its lifetime, and before each division event a single yeast cell needs to import about 14 million r-proteins into its nucleus in order to make about 200,000 ribosomes. However, many details of this process are mysterious. In particular, many r-proteins are known to be unstable: meaning that, left to their own devices, r-proteins are highly likely to aggregate, which would prevent them becoming part of a ribosome. Now, Schütz et al. have figured out how a carrier protein called Tsr2 makes sure that an r-protein called eS26 does indeed become part of a ribosome. The human disorder known as Diamond-Blackfan anemia is caused by a mutation in the gene for eS26. The eS26 proteins are ferried to the cell nucleus on specialized transport vehicles. Schütz et al. have now shown that the Tsr2 carrier protein unloads the r-protein from the transport vehicle in the nucleus, and then binds it. This means that the r-protein does not form an aggregate. Finally, the Tsr2 carrier protein transfers the r-protein to the pre-ribosome. This is the first time that a carrier protein that unloads an r-protein cargo from its transport vehicle, to ensure safe delivery to the pre-ribosome, has been identified. DOI:http://dx.doi.org/10.7554/eLife.03473.002
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Affiliation(s)
- Sabina Schütz
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland Molecular Life Science Graduate School, University of Zurich, Zurich, Switzerland
| | - Ute Fischer
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Martin Altvater
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland Molecular Life Science Graduate School, University of Zurich, Zurich, Switzerland
| | - Purnima Nerurkar
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland Molecular Life Science Graduate School, University of Zurich, Zurich, Switzerland
| | - Cohue Peña
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Michaela Gerber
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Yiming Chang
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Stefanie Caesar
- Institute of Medical Biochemistry and Molecular Biology, Universität des Saarlandes, Homburg, Germany
| | - Olga T Schubert
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, Zurich, Switzerland Systems Biology Graduate School, Zurich, Zurich, Switzerland
| | - Gabriel Schlenstedt
- Institute of Medical Biochemistry and Molecular Biology, Universität des Saarlandes, Homburg, Germany
| | - Vikram G Panse
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
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91
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Ferreira-Cerca S, Kiburu I, Thomson E, LaRonde N, Hurt E. Dominant Rio1 kinase/ATPase catalytic mutant induces trapping of late pre-40S biogenesis factors in 80S-like ribosomes. Nucleic Acids Res 2014; 42:8635-47. [PMID: 24948609 PMCID: PMC4117770 DOI: 10.1093/nar/gku542] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
During eukaryotic ribosome biogenesis, members of the conserved atypical serine/threonine protein kinase family, the RIO kinases (Rio1, Rio2 and Rio3) function in small ribosomal subunit biogenesis. Structural analysis of Rio2 indicated a role as a conformation-sensing ATPase rather than a kinase to regulate its dynamic association with the pre-40S subunit. However, it remained elusive at which step and by which mechanism the other RIO kinase members act. Here, we have determined the crystal structure of the human Rio1-ATP-Mg(2+) complex carrying a phosphoaspartate in the active site indicative of ATPase activity. Structure-based mutations in yeast showed that Rio1's catalytic activity regulates its pre-40S association. Furthermore, we provide evidence that Rio1 associates with a very late pre-40S via its conserved C-terminal domain. Moreover, a rio1 dominant-negative mutant defective in ATP hydrolysis induced trapping of late biogenesis factors in pre-ribosomal particles, which turned out not to be pre-40S but 80S-like ribosomes. Thus, the RIO kinase fold generates a versatile ATPase enzyme, which in the case of Rio1 is activated following the Rio2 step to regulate one of the final 40S maturation events, at which time the 60S subunit is recruited for final quality control check.
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Affiliation(s)
- Sébastien Ferreira-Cerca
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany Universität Regensburg, Biochemie-Zentrum Regensburg (BZR), Lehrstuhl Biochemie III, 93053 Regensburg, Germany
| | - Irene Kiburu
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Emma Thomson
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Nicole LaRonde
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA University of Maryland Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201, USA
| | - Ed Hurt
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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92
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Thomson E, Ferreira-Cerca S, Hurt E. Eukaryotic ribosome biogenesis at a glance. J Cell Sci 2014; 126:4815-21. [PMID: 24172536 DOI: 10.1242/jcs.111948] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ribosomes play a pivotal role in the molecular life of every cell. Moreover, synthesis of ribosomes is one of the most energetically demanding of all cellular processes. In eukaryotic cells, ribosome biogenesis requires the coordinated activity of all three RNA polymerases and the orchestrated work of many (>200) transiently associated ribosome assembly factors. The biogenesis of ribosomes is a tightly regulated activity and it is inextricably linked to other fundamental cellular processes, including growth and cell division. Furthermore, recent studies have demonstrated that defects in ribosome biogenesis are associated with several hereditary diseases. In this Cell Science at a Glance article and the accompanying poster, we summarise the current knowledge on eukaryotic ribosome biogenesis, with an emphasis on the yeast model system.
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Affiliation(s)
- Emma Thomson
- Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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93
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Chen YL, Capeyrou R, Humbert O, Mouffok S, Kadri YA, Lebaron S, Henras AK, Henry Y. The telomerase inhibitor Gno1p/PINX1 activates the helicase Prp43p during ribosome biogenesis. Nucleic Acids Res 2014; 42:7330-45. [PMID: 24823796 PMCID: PMC4066782 DOI: 10.1093/nar/gku357] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We provide evidence that a central player in ribosome synthesis, the ribonucleic acid helicase Prp43p, can be activated by yeast Gno1p and its human ortholog, the telomerase inhibitor PINX1. Gno1p and PINX1 expressed in yeast interact with Prp43p and the integrity of their G-patch domain is required for this interaction. Moreover, PINX1 interacts with human PRP43 (DHX15) in HeLa cells. PINX1 directly binds to yeast Prp43p and stimulates its adenosine triphosphatase activity, while alterations of the G patch abolish formation of the PINX1/Prp43p complex and the stimulation of Prp43p. In yeast, lack of Gno1p leads to a decrease in the levels of pre-40S and intermediate pre-60S pre-ribosomal particles, defects that can be corrected by PINX1 expression. We show that Gno1p associates with 90S and early pre-60S pre-ribosomal particles and is released from intermediate pre-60S particles. G-patch alterations in Gno1p or PINX1 that inhibit their interactions with Prp43p completely abolish their function in yeast ribosome biogenesis. Altogether, our results suggest that activation of Prp43p by Gno1p/PINX1 within early pre-ribosomal particles is crucial for their subsequent maturation.
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Affiliation(s)
- Yan-Ling Chen
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Régine Capeyrou
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Odile Humbert
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Saïda Mouffok
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Yasmine Al Kadri
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Simon Lebaron
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Anthony K Henras
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
| | - Yves Henry
- Equipe labellisée Ligue Contre le Cancer, LBME, CNRS and Toulouse University, Toulouse 31062, France
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94
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Liu Y, Huang H, Yuan B, Zhuang LY, Luo TP, Zhang Q. Lentivirus-mediated knockdown of NOB1 suppresses the proliferation of colon cancer cells. ZEITSCHRIFT FUR GASTROENTEROLOGIE 2014; 52:429-35. [PMID: 24824907 DOI: 10.1055/s-0033-1356338] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
NOB1 is important for ribosome biogenesis and protein degradation. Previous studies showed that it could regulate the growth and colony-formation ability of ovarian, breast and hepatocellular carcinoma cells. However, its function in colon cancer cells is largely unknown. In this study, we found that NOB1 could express in 6 different colon cancer cell lines. Lentivirus-mediated shRNA targeted NOB1 could suppress the endogenous gene expression. NOB1 depletion significantly inhibited cell proliferation and colony formation ability, as determined by MTT and colony formation assays. Flow cytometry analysis showed NOB1 silencing arrested cell cycle in G0 / G1 phase. Moreover, the percentage of cells at sub-G1 phase dramatically increased after NOB1 knockdown. These results indicate that NOB1 may play an important role in the growth and tumorigensis of colon cancer and knockdown of NOB1 may be a potential therapeutic method for colon cancer in the future.
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95
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Assembly and nuclear export of pre-ribosomal particles in budding yeast. Chromosoma 2014; 123:327-44. [PMID: 24817020 DOI: 10.1007/s00412-014-0463-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/18/2014] [Accepted: 04/07/2014] [Indexed: 11/27/2022]
Abstract
The ribosome is responsible for the final step of decoding genetic information into proteins. Therefore, correct assembly of ribosomes is a fundamental task for all living cells. In eukaryotes, the construction of the ribosome which begins in the nucleolus requires coordinated efforts of >350 specialized factors that associate with pre-ribosomal particles at distinct stages to perform specific assembly steps. On their way through the nucleus, diverse energy-consuming enzymes are thought to release assembly factors from maturing pre-ribosomal particles after accomplishing their task(s). Subsequently, recruitment of export factors prepares pre-ribosomal particles for transport through nuclear pore complexes. Pre-ribosomes are exported into the cytoplasm in a functionally inactive state, where they undergo final maturation before initiating translation. Accumulating evidence indicates a tight coupling between nuclear export, cytoplasmic maturation, and final proofreading of the ribosome. In this review, we summarize our current understanding of nuclear export of pre-ribosomal subunits and cytoplasmic maturation steps that render pre-ribosomal subunits translation-competent.
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96
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Abstract
Superfamily 2 helicase proteins are ubiquitous in RNA biology and have an extraordinarily broad set of functional roles. Central among these roles are the promotion of rearrangements of structured RNAs and the remodeling of ribonucleoprotein complexes (RNPs), allowing formation of native RNA structure or progression through a functional cycle of structures. Although all superfamily 2 helicases share a conserved helicase core, they are divided evolutionarily into several families, and it is principally proteins from three families, the DEAD-box, DEAH/RHA, and Ski2-like families, that function to manipulate structured RNAs and RNPs. Strikingly, there are emerging differences in the mechanisms of these proteins, both between families and within the largest family (DEAD-box), and these differences appear to be tuned to their RNA or RNP substrates and their specific roles. This review outlines basic mechanistic features of the three families and surveys individual proteins and the current understanding of their biological substrates and mechanisms.
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Affiliation(s)
- Inga Jarmoskaite
- Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712; ,
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97
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García-Gómez JJ, Fernández-Pevida A, Lebaron S, Rosado IV, Tollervey D, Kressler D, de la Cruz J. Final pre-40S maturation depends on the functional integrity of the 60S subunit ribosomal protein L3. PLoS Genet 2014; 10:e1004205. [PMID: 24603549 PMCID: PMC3945201 DOI: 10.1371/journal.pgen.1004205] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 01/13/2014] [Indexed: 01/21/2023] Open
Abstract
Ribosomal protein L3 is an evolutionarily conserved protein that participates in the assembly of early pre-60S particles. We report that the rpl3[W255C] allele, which affects the affinity and function of translation elongation factors, impairs cytoplasmic maturation of 20S pre-rRNA. This was not seen for other mutations in or depletion of L3 or other 60S ribosomal proteins. Surprisingly, pre-40S particles containing 20S pre-rRNA form translation-competent 80S ribosomes, and translation inhibition partially suppresses 20S pre-rRNA accumulation. The GTP-dependent translation initiation factor Fun12 (yeast eIF5B) shows similar in vivo binding to ribosomal particles from wild-type and rpl3[W255C] cells. However, the GTPase activity of eIF5B failed to stimulate processing of 20S pre-rRNA when assayed with ribosomal particles purified from rpl3[W255C] cells. We conclude that L3 plays an important role in the function of eIF5B in stimulating 3′ end processing of 18S rRNA in the context of 80S ribosomes that have not yet engaged in translation. These findings indicate that the correct conformation of the GTPase activation region is assessed in a quality control step during maturation of cytoplasmic pre-ribosomal particles. Recent progress has provided us with detailed knowledge of the structure and function of eukaryotic ribosomes. However, our understanding of the intricate processes of pre-ribosome assembly and the transition to translation-competent ribosomal subunits remains incomplete. The early and intermediate steps of ribosome assembly occur successively in the nucleolus and nucleoplasm. The pre-ribosomal subunits are then exported to the cytoplasm where final maturation steps, notably including D site cleavage of the 20S pre-rRNA to mature 18S rRNA, confer subunit joining and translation competence. Recent evidence indicates that pre-40S subunits are subject to a quality control step involving the GTP-dependent translation initiation factor eIF5B/Fun12, in the context of 80S-like ribosomes. Here, we demonstrate the involvement of 60S subunits in promoting 20S pre-rRNA cleavage. In particular, we show that a specific point mutation in the 60S subunit ribosomal protein L3 (rpl3[W255C]) leads to the accumulation of pre-40S particles that contain the 20S pre-rRNA but are translation-competent. Notably, this mutation prevents the stimulation of the GTPase activity of eIF5B/Fun12, which is also required for site D cleavage. We conclude that L3 plays an important role in regulating the function of eIF5B/Fun12 during 3′ end processing of 18S rRNA at site D, in the context of 80S ribosomes that have not yet engaged in translation.
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MESH Headings
- Alleles
- Cytoplasm/genetics
- Cytoplasm/metabolism
- Eukaryotic Initiation Factors/genetics
- Mutation
- Proteasome Endopeptidase Complex/genetics
- Proteasome Endopeptidase Complex/metabolism
- Protein Binding
- RNA Precursors/genetics
- RNA, Ribosomal, 18S/genetics
- Ribosomal Protein L3
- Ribosomal Proteins/genetics
- Ribosomal Proteins/metabolism
- Ribosome Subunits, Large, Eukaryotic/genetics
- Ribosome Subunits, Large, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/genetics
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Saccharomyces cerevisiae/genetics
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Affiliation(s)
- Juan J. García-Gómez
- Departamento de Genética, Universidad de Sevilla, and Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - Antonio Fernández-Pevida
- Departamento de Genética, Universidad de Sevilla, and Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - Simon Lebaron
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Iván V. Rosado
- Departamento de Genética, Universidad de Sevilla, and Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jesús de la Cruz
- Departamento de Genética, Universidad de Sevilla, and Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- * E-mail:
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98
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Abstract
Construction of the eukaryotic ribosome begins in the nucleolus and requires >300 evolutionarily conserved nonribosomal trans-acting factors, which transiently associate with preribosomal subunits at distinct assembly stages. A subset of trans-acting and transport factors passage assembled preribosomal subunits in a functionally inactive state through the nuclear pore complexes (NPC) into the cytoplasm, where they undergo final maturation before initiating translation. Here, we summarize the repertoire of tools developed in the model organism budding yeast that are spearheading the functional analyses of trans-acting factors involved in the assembly and intracellular transport of preribosomal subunits. We elaborate on different GFP-tagged ribosomal protein reporters and a pre-rRNA reporter that reliably monitors the movement of preribosomal particles from the nucleolus to cytoplasm. We discuss the powerful yeast heterokaryon assay, which can be employed to uncover shuttling trans-acting factors that need to accompany preribosomal subunits to the cytoplasm to be released prior to initiating translation. Moreover, we present two biochemical approaches, namely sucrose gradient analyses and tandem affinity purification, that are rapidly facilitating the uncovering of regulatory processes that control the compositional dynamics of trans-acting factors on maturing preribosomal particles. Altogether, these approaches when combined with traditional analytical biochemistry, targeted proteomics and structural methodologies, will contribute to the dissection of the assembly and intracellular transport of preribosomal subunits, as well as other macromolecular assemblies that influence diverse biological pathways.
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MESH Headings
- Biological Transport/genetics
- Green Fluorescent Proteins/genetics
- In Situ Hybridization, Fluorescence/methods
- Karyopherins/genetics
- Mass Spectrometry/methods
- Microscopy, Fluorescence/methods
- Nuclear Pore/genetics
- Nuclear Pore/metabolism
- Nucleolus Organizer Region/genetics
- RNA, Ribosomal/biosynthesis
- RNA, Ribosomal/genetics
- Receptors, Cytoplasmic and Nuclear/genetics
- Ribosome Subunits, Large, Eukaryotic/genetics
- Ribosome Subunits, Large, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/genetics
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Ultracentrifugation/methods
- Exportin 1 Protein
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Affiliation(s)
- Martin Altvater
- Institute of Biochemistry (IBC), ETH Zürich, Otto-Stern-Weg 3, Zurich, Switzerland; MLS Program, Life Science Zurich Graduate School, Winterthurerstrasse 190, Zurich, Switzerland
| | - Sabina Schütz
- Institute of Biochemistry (IBC), ETH Zürich, Otto-Stern-Weg 3, Zurich, Switzerland; MLS Program, Life Science Zurich Graduate School, Winterthurerstrasse 190, Zurich, Switzerland
| | - Yiming Chang
- Institute of Biochemistry (IBC), ETH Zürich, Otto-Stern-Weg 3, Zurich, Switzerland
| | - Vikram Govind Panse
- Institute of Biochemistry (IBC), ETH Zürich, Otto-Stern-Weg 3, Zurich, Switzerland
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99
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Yoshimoto R, Okawa K, Yoshida M, Ohno M, Kataoka N. Identification of a novel component C2ORF3 in the lariat-intron complex: lack of C2ORF3 interferes with pre-mRNA splicing via intron turnover pathway. Genes Cells 2013; 19:78-87. [DOI: 10.1111/gtc.12114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 10/14/2013] [Indexed: 12/18/2022]
Affiliation(s)
- Rei Yoshimoto
- Chemical Genetics Laboratory; RIKEN Advanced Science Institute; Wako Saitama 351-0198 Japan
- Institute for Virus Research; Kyoto University; Sakyo-ku Kyoto 606-8507 Japan
| | - Katsuya Okawa
- Drug Research Laboratories; Kyowa Hakko Kirin Co., Ltd; Nagaizumi Shizuoka 411-8731 Japan
| | - Minoru Yoshida
- Chemical Genetics Laboratory; RIKEN Advanced Science Institute; Wako Saitama 351-0198 Japan
| | - Mutsuhito Ohno
- Institute for Virus Research; Kyoto University; Sakyo-ku Kyoto 606-8507 Japan
| | - Naoyuki Kataoka
- Laboratory for Malignancy Control Research; Medical Innovation Center; Kyoto University Graduate School of Medicine; Sakyo-ku Kyoto 606-8507 Japan
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Pratte D, Singh U, Murat G, Kressler D. Mak5 and Ebp2 act together on early pre-60S particles and their reduced functionality bypasses the requirement for the essential pre-60S factor Nsa1. PLoS One 2013; 8:e82741. [PMID: 24312670 PMCID: PMC3846774 DOI: 10.1371/journal.pone.0082741] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 10/28/2013] [Indexed: 11/18/2022] Open
Abstract
Ribosomes are the molecular machines that translate mRNAs into proteins. The synthesis of ribosomes is therefore a fundamental cellular process and consists in the ordered assembly of 79 ribosomal proteins (r-proteins) and four ribosomal RNAs (rRNAs) into a small 40S and a large 60S ribosomal subunit that form the translating 80S ribosomes. Most of our knowledge concerning this dynamic multi-step process comes from studies with the yeast Saccharomyces cerevisiae, which have shown that assembly and maturation of pre-ribosomal particles, as they travel from the nucleolus to the cytoplasm, relies on a multitude (>200) of biogenesis factors. Amongst these are many energy-consuming enzymes, including 19 ATP-dependent RNA helicases and three AAA-ATPases. We have previously shown that the AAA-ATPase Rix7 promotes the release of the essential biogenesis factor Nsa1 from late nucleolar pre-60S particles. Here we show that mutant alleles of genes encoding the DEAD-box RNA helicase Mak5, the C/D-box snoRNP component Nop1 and the rRNA-binding protein Nop4 bypass the requirement for Nsa1. Interestingly, dominant-negative alleles of RIX7 retain their phenotype in the absence of Nsa1, suggesting that Rix7 may have additional nuclear substrates besides Nsa1. Mak5 is associated with the Nsa1 pre-60S particle and synthetic lethal screens with mak5 alleles identified the r-protein Rpl14 and the 60S biogenesis factors Ebp2, Nop16 and Rpf1, which are genetically linked amongst each other. We propose that these 'Mak5 cluster' factors orchestrate the structural arrangement of a eukaryote-specific 60S subunit surface composed of Rpl6, Rpl14 and Rpl16 and rRNA expansion segments ES7L and ES39L. Finally, over-expression of Rix7 negatively affects growth of mak5 and ebp2 mutant cells both in the absence and presence of Nsa1, suggesting that Rix7, at least when excessively abundant, may act on structurally defective pre-60S subunits and may subject these to degradation.
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Affiliation(s)
- Dagmar Pratte
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Ujjwala Singh
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail:
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