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The Terminal Extensions of Dbp7 Influence Growth and 60S Ribosomal Subunit Biogenesis in Saccharomyces cerevisiae. Int J Mol Sci 2023; 24:ijms24043460. [PMID: 36834876 PMCID: PMC9960301 DOI: 10.3390/ijms24043460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 01/30/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Ribosome synthesis is a complex process that involves a large set of protein trans-acting factors, among them DEx(D/H)-box helicases. These are enzymes that carry out remodelling activities onto RNAs by hydrolysing ATP. The nucleolar DEGD-box protein Dbp7 is required for the biogenesis of large 60S ribosomal subunits. Recently, we have shown that Dbp7 is an RNA helicase that regulates the dynamic base-pairing between the snR190 small nucleolar RNA and the precursors of the ribosomal RNA within early pre-60S ribosomal particles. As the rest of DEx(D/H)-box proteins, Dbp7 has a modular organization formed by a helicase core region, which contains conserved motifs, and variable, non-conserved N- and C-terminal extensions. The role of these extensions remains unknown. Herein, we show that the N-terminal domain of Dbp7 is necessary for efficient nuclear import of the protein. Indeed, a basic bipartite nuclear localization signal (NLS) could be identified in its N-terminal domain. Removal of this putative NLS impairs, but does not abolish, Dbp7 nuclear import. Both N- and C-terminal domains are required for normal growth and 60S ribosomal subunit synthesis. Furthermore, we have studied the role of these domains in the association of Dbp7 with pre-ribosomal particles. Altogether, our results show that the N- and C-terminal domains of Dbp7 are important for the optimal function of this protein during ribosome biogenesis.
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2
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Bhutada P, Favre S, Jaafar M, Hafner J, Liesinger L, Unterweger S, Bischof K, Darnhofer B, Siva Sankar D, Rechberger G, Abou Merhi R, Lebaron S, Birner-Gruenberger R, Kressler D, Henras AK, Pertschy B. Rbp95 binds to 25S rRNA helix H95 and cooperates with the Npa1 complex during early pre-60S particle maturation. Nucleic Acids Res 2022; 50:10053-10077. [PMID: 36018804 PMCID: PMC9508819 DOI: 10.1093/nar/gkac724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 08/05/2022] [Accepted: 08/12/2022] [Indexed: 11/21/2022] Open
Abstract
Eukaryotic ribosome synthesis involves more than 200 assembly factors, which promote ribosomal RNA (rRNA) processing, modification and folding, and assembly of ribosomal proteins. The formation and maturation of the earliest pre-60S particles requires structural remodeling by the Npa1 complex, but is otherwise still poorly understood. Here, we introduce Rbp95 (Ycr016w), a constituent of early pre-60S particles, as a novel ribosome assembly factor. We show that Rbp95 is both genetically and physically linked to most Npa1 complex members and to ribosomal protein Rpl3. We demonstrate that Rbp95 is an RNA-binding protein containing two independent RNA-interacting domains. In vivo, Rbp95 associates with helix H95 in the 3′ region of the 25S rRNA, in close proximity to the binding sites of Npa1 and Rpl3. Additionally, Rbp95 interacts with several snoRNAs. The absence of Rbp95 results in alterations in the protein composition of early pre-60S particles. Moreover, combined mutation of Rbp95 and Npa1 complex members leads to a delay in the maturation of early pre-60S particles. We propose that Rbp95 acts together with the Npa1 complex during early pre-60S maturation, potentially by promoting pre-rRNA folding events within pre-60S particles.
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Affiliation(s)
- Priya Bhutada
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Sébastien Favre
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Mariam Jaafar
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.,Genomic Stability and Biotherapy (GSBT) Laboratory, Faculty of Sciences, Rafik Hariri Campus, Lebanese University, Beirut, Lebanon
| | - Jutta Hafner
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Laura Liesinger
- BioTechMed-Graz, Graz, Austria.,Diagnostic and Research Institute of Pathology, Medical University of Graz, 8010 Graz, Austria
| | - Stefan Unterweger
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Karin Bischof
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Barbara Darnhofer
- BioTechMed-Graz, Graz, Austria.,Diagnostic and Research Institute of Pathology, Medical University of Graz, 8010 Graz, Austria
| | - Devanarayanan Siva Sankar
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Gerald Rechberger
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Raghida Abou Merhi
- Genomic Stability and Biotherapy (GSBT) Laboratory, Faculty of Sciences, Rafik Hariri Campus, Lebanese University, Beirut, Lebanon
| | - Simon Lebaron
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
| | - Ruth Birner-Gruenberger
- BioTechMed-Graz, Graz, Austria.,Diagnostic and Research Institute of Pathology, Medical University of Graz, 8010 Graz, Austria.,Institute of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9/E164, 1060 Vienna, Austria
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Anthony K Henras
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
| | - Brigitte Pertschy
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria.,BioTechMed-Graz, Graz, Austria
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3
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Sailer C, Jansen J, Sekulski K, Cruz VE, Erzberger JP, Stengel F. A comprehensive landscape of 60S ribosome biogenesis factors. Cell Rep 2022; 38:110353. [PMID: 35139378 PMCID: PMC8884084 DOI: 10.1016/j.celrep.2022.110353] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 03/02/2021] [Accepted: 01/19/2022] [Indexed: 01/03/2023] Open
Abstract
Eukaryotic ribosome biogenesis is facilitated and regulated by numerous ribosome biogenesis factors (RBFs). High-resolution cryoelectron microscopy (cryo-EM) maps have defined the molecular interactions of RBFs during maturation, but many transient and dynamic interactions, particularly during early assembly, remain uncharacterized. Using quantitative proteomics and crosslinking coupled to mass spectrometry (XL-MS) data from an extensive set of pre-ribosomal particles, we derive a comprehensive and time-resolved interaction map of RBF engagement during 60S maturation. We localize 22 previously unmapped RBFs to specific biogenesis intermediates and validate our results by mapping the catalytic activity of the methyltransferases Bmt2 and Rcm1 to their predicted nucleolar 60S intermediates. Our analysis reveals the interaction sites for the RBFs Noc2 and Ecm1 and elucidates the interaction map and timing of 60S engagement by the DEAD-box ATPases Dbp9 and Dbp10. Our data provide a powerful resource for future studies of 60S ribosome biogenesis. In this study, Sailer et al. generate a comprehensive and precise timeline of ribosome biogenesis factor (RBF) engagement during 60S maturation and localize previously unmapped RBFs in the yeast Saccharomyces cerevisiae. Overall, their data represent an essential resource for future structural studies of large subunit ribosome biogenesis.
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Affiliation(s)
- Carolin Sailer
- Department of Biology, University of Konstanz, Universitätsstrae 10, 78457 Konstanz, Germany; Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrae 10, 78457 Konstanz, Germany
| | - Jasmin Jansen
- Department of Biology, University of Konstanz, Universitätsstrae 10, 78457 Konstanz, Germany; Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrae 10, 78457 Konstanz, Germany
| | - Kamil Sekulski
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
| | - Victor E Cruz
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
| | - Jan P Erzberger
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA.
| | - Florian Stengel
- Department of Biology, University of Konstanz, Universitätsstrae 10, 78457 Konstanz, Germany; Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrae 10, 78457 Konstanz, Germany.
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4
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Mitterer V, Pertschy B. RNA folding and functions of RNA helicases in ribosome biogenesis. RNA Biol 2022; 19:781-810. [PMID: 35678541 PMCID: PMC9196750 DOI: 10.1080/15476286.2022.2079890] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic ribosome biogenesis involves the synthesis of ribosomal RNA (rRNA) and its stepwise folding into the unique structure present in mature ribosomes. rRNA folding starts already co-transcriptionally in the nucleolus and continues when pre-ribosomal particles further maturate in the nucleolus and upon their transit to the nucleoplasm and cytoplasm. While the approximate order of folding of rRNA subdomains is known, especially from cryo-EM structures of pre-ribosomal particles, the actual mechanisms of rRNA folding are less well understood. Both small nucleolar RNAs (snoRNAs) and proteins have been implicated in rRNA folding. snoRNAs hybridize to precursor rRNAs (pre-rRNAs) and thereby prevent premature folding of the respective rRNA elements. Ribosomal proteins (r-proteins) and ribosome assembly factors might have a similar function by binding to rRNA elements and preventing their premature folding. Besides that, a small group of ribosome assembly factors are thought to play a more active role in rRNA folding. In particular, multiple RNA helicases participate in individual ribosome assembly steps, where they are believed to coordinate RNA folding/unfolding events or the release of proteins from the rRNA. In this review, we summarize the current knowledge on mechanisms of RNA folding and on the specific function of the individual RNA helicases involved. As the yeast Saccharomyces cerevisiae is the organism in which ribosome biogenesis and the role of RNA helicases in this process is best studied, we focused our review on insights from this model organism, but also make comparisons to other organisms where applicable.
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Affiliation(s)
- Valentin Mitterer
- Biochemistry Center, Heidelberg University, Im Neuenheimer Feld 328, Heidelberg, Germany
- BioTechMed-Graz, Graz, Austria
| | - Brigitte Pertschy
- BioTechMed-Graz, Graz, Austria
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, Graz, Austria
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5
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Aquino GRR, Hackert P, Krogh N, Pan KT, Jaafar M, Henras AK, Nielsen H, Urlaub H, Bohnsack KE, Bohnsack MT. The RNA helicase Dbp7 promotes domain V/VI compaction and stabilization of inter-domain interactions during early 60S assembly. Nat Commun 2021; 12:6152. [PMID: 34686661 PMCID: PMC8536713 DOI: 10.1038/s41467-021-26208-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 09/22/2021] [Indexed: 02/07/2023] Open
Abstract
Early pre-60S ribosomal particles are poorly characterized, highly dynamic complexes that undergo extensive rRNA folding and compaction concomitant with assembly of ribosomal proteins and exchange of assembly factors. Pre-60S particles contain numerous RNA helicases, which are likely regulators of accurate and efficient formation of appropriate rRNA structures. Here we reveal binding of the RNA helicase Dbp7 to domain V/VI of early pre-60S particles in yeast and show that in the absence of this protein, dissociation of the Npa1 scaffolding complex, release of the snR190 folding chaperone, recruitment of the A3 cluster factors and binding of the ribosomal protein uL3 are impaired. uL3 is critical for formation of the peptidyltransferase center (PTC) and is responsible for stabilizing interactions between the 5′ and 3′ ends of the 25S, an essential pre-requisite for subsequent pre-60S maturation events. Highlighting the importance of pre-ribosome remodeling by Dbp7, our data suggest that in the absence of Dbp7 or its catalytic activity, early pre-ribosomal particles are targeted for degradation. Early steps of large 60S ribosomal subunit biogenesis are not well understood. Here, the authors combine biochemical experiments with protein-RNA crosslinking and mass spectrometry to show that the RNA helicase Dbp7 is key player during early 60S ribosomal assembly. Dbp7 regulates a series of events driving compaction of domain V/VI in early pre60S ribosomal particles.
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Affiliation(s)
- Gerald Ryan R Aquino
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Philipp Hackert
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Nicolai Krogh
- Department of Cellular and Molecular Medicine, University of Copenhagen, 2200N, Copenhagen, Denmark
| | - Kuan-Ting Pan
- Max Planck Institute for Biophysical Chemistry, Bioanalytical Mass Spectrometry, 37077, Göttingen, Germany.,Hematology/Oncology, Department of Medicine II, Johann Wolfgang Goethe University, 60590, Frankfurt am Main, Germany.,Frankfurt Cancer Institute, Goethe University, 60596, Frankfurt am Main, Germany
| | - Mariam Jaafar
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31062, Toulouse, France
| | - Anthony K Henras
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 31062, Toulouse, France
| | - Henrik Nielsen
- Department of Cellular and Molecular Medicine, University of Copenhagen, 2200N, Copenhagen, Denmark.,Genomics Group, Faculty of Biosciences and Aquaculture, Nord University, 8049, Bodø, Norway
| | - Henning Urlaub
- Max Planck Institute for Biophysical Chemistry, Bioanalytical Mass Spectrometry, 37077, Göttingen, Germany.,Institute for Clinical Chemistry, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany. .,Göttingen Centre for Molecular Biosciences, Georg-August-University, Justus-von-Liebig Weg 11, 37077, Göttingen, Germany.
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6
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Dong C, Schultz JC, Liu W, Lian J, Huang L, Xu Z, Zhao H. Identification of novel metabolic engineering targets for S-adenosyl-L-methionine production in Saccharomyces cerevisiae via genome-scale engineering. Metab Eng 2021; 66:319-327. [PMID: 33713797 DOI: 10.1016/j.ymben.2021.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/18/2021] [Accepted: 03/03/2021] [Indexed: 12/13/2022]
Abstract
S-Adenosyl-L-methionine (SAM) is an important intracellular metabolite and widely used for treatment of various diseases. Although high level production of SAM had been achieved in yeast, novel metabolic engineering strategies are needed to further enhance SAM production for industrial applications. Here genome-scale engineering (GSE) was performed to identify new targets for SAM overproduction using the multi-functional genome-wide CRISPR (MAGIC) system, and the effects of these newly identified targets were further validated in industrial yeast strains. After 3 rounds of FACS screening and characterization, numerous novel targets for enhancing SAM production were identified. In addition, transcriptomic and metabolomic analyses were performed to investigate the molecular mechanisms for enhanced SAM accumulation. The best combination (upregulation of SNZ3, RFC4, and RPS18B) improved SAM productivity by 2.2-fold and 1.6-fold in laboratory and industrial yeast strains, respectively. Using GSE of laboratory yeast strains to guide industrial yeast strain engineering presents an effective approach to design microbial cell factories for industrial applications.
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Affiliation(s)
- Chang Dong
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - J Carl Schultz
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Wei Liu
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jiazhang Lian
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China; Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310027, China.
| | - Lei Huang
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Zhinan Xu
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China.
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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7
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Varland S, Aksnes H, Kryuchkov F, Impens F, Van Haver D, Jonckheere V, Ziegler M, Gevaert K, Van Damme P, Arnesen T. N-terminal Acetylation Levels Are Maintained During Acetyl-CoA Deficiency in Saccharomyces cerevisiae. Mol Cell Proteomics 2018; 17:2309-2323. [PMID: 30150368 PMCID: PMC6283290 DOI: 10.1074/mcp.ra118.000982] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/22/2018] [Indexed: 12/17/2022] Open
Abstract
Nt-acetylation is a prevalent protein modification catalyzed by N-terminal acetyltransferases using acetyl-CoA as acetyl donor. Here, we performed a global analysis of Nt-acetylation in yeast following nutrient starvation. Contrary to histone acetylation, which is sensitive to acetyl-CoA levels, we demonstrate that Nt-acetylation remains largely unaffected to changes in cellular metabolism. We did, however, identify two protein groups that were differentially Nt-acetylated, one showing the same sensitivity to acetyl-CoA as histones. We propose that specific, rather than global, Nt-acetylation events are subject to metabolic regulation. N-terminal acetylation (Nt-acetylation) is a highly abundant protein modification in eukaryotes and impacts a wide range of cellular processes, including protein quality control and stress tolerance. Despite its prevalence, the mechanisms regulating Nt-acetylation are still nebulous. Here, we present the first global study of Nt-acetylation in yeast cells as they progress to stationary phase in response to nutrient starvation. Surprisingly, we found that yeast cells maintain their global Nt-acetylation levels upon nutrient depletion, despite a marked decrease in acetyl-CoA levels. We further observed two distinct sets of protein N termini that display differential and opposing Nt-acetylation behavior upon nutrient starvation, indicating a dynamic process. The first protein cluster was enriched for annotated N termini showing increased Nt-acetylation in stationary phase compared with exponential growth phase. The second protein cluster was conversely enriched for alternative nonannotated N termini (i.e. N termini indicative of shorter N-terminal proteoforms) and, like histones, showed reduced acetylation levels in stationary phase when acetyl-CoA levels were low. Notably, the degree of Nt-acetylation of Pcl8, a negative regulator of glycogen biosynthesis and two components of the pre-ribosome complex (Rsa3 and Rpl7a) increased during starvation. Moreover, the steady-state levels of these proteins were regulated both by starvation and NatA activity. In summary, this study represents the first comprehensive analysis of metabolic regulation of Nt-acetylation and reveals that specific, rather than global, Nt-acetylation events are subject to metabolic regulation.
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Affiliation(s)
- Sylvia Varland
- Department of Biomedicine, University of Bergen, N-5020 Bergen, Norway; Department of Biological Sciences, University of Bergen, N-5020 Bergen, Norway; Donnelly Center for Cellular and Bio‡molecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.
| | - Henriette Aksnes
- Department of Biomedicine, University of Bergen, N-5020 Bergen, Norway; Department of Biological Sciences, University of Bergen, N-5020 Bergen, Norway
| | - Fedor Kryuchkov
- Department of Biomedicine, University of Bergen, N-5020 Bergen, Norway
| | - Francis Impens
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, B-9000 Ghent, Belgium; VIB Proteomics Core, B-9000 Ghent, Belgium
| | - Delphi Van Haver
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, B-9000 Ghent, Belgium; VIB Proteomics Core, B-9000 Ghent, Belgium
| | - Veronique Jonckheere
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, B-9000 Ghent, Belgium
| | - Mathias Ziegler
- Department of Biomedicine, University of Bergen, N-5020 Bergen, Norway; Department of Biological Sciences, University of Bergen, N-5020 Bergen, Norway
| | - Kris Gevaert
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, B-9000 Ghent, Belgium
| | - Petra Van Damme
- Department of Biomolecular Medicine, Ghent University, B-9000 Ghent, Belgium.
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, N-5020 Bergen, Norway; Department of Biological Sciences, University of Bergen, N-5020 Bergen, Norway; Department of Surgery, Haukeland University Hospital, N-5021 Bergen, Norway
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8
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Woolford JL, Baserga SJ. Ribosome biogenesis in the yeast Saccharomyces cerevisiae. Genetics 2013; 195:643-81. [PMID: 24190922 PMCID: PMC3813855 DOI: 10.1534/genetics.113.153197] [Citation(s) in RCA: 548] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/26/2013] [Indexed: 01/09/2023] Open
Abstract
Ribosomes are highly conserved ribonucleoprotein nanomachines that translate information in the genome to create the proteome in all cells. In yeast these complex particles contain four RNAs (>5400 nucleotides) and 79 different proteins. During the past 25 years, studies in yeast have led the way to understanding how these molecules are assembled into ribosomes in vivo. Assembly begins with transcription of ribosomal RNA in the nucleolus, where the RNA then undergoes complex pathways of folding, coupled with nucleotide modification, removal of spacer sequences, and binding to ribosomal proteins. More than 200 assembly factors and 76 small nucleolar RNAs transiently associate with assembling ribosomes, to enable their accurate and efficient construction. Following export of preribosomes from the nucleus to the cytoplasm, they undergo final stages of maturation before entering the pool of functioning ribosomes. Elaborate mechanisms exist to monitor the formation of correct structural and functional neighborhoods within ribosomes and to destroy preribosomes that fail to assemble properly. Studies of yeast ribosome biogenesis provide useful models for ribosomopathies, diseases in humans that result from failure to properly assemble ribosomes.
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Affiliation(s)
- John L. Woolford
- Department of Biological Sciences, Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Susan J. Baserga
- Molecular Biophysics and Biochemistry, Genetics and Therapeutic Radiology, Yale University, New Haven, Connecticut 06520-8024
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9
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Rosado IV, Dez C, Lebaron S, Caizergues-Ferrer M, Henry Y, de la Cruz J. Characterization of Saccharomyces cerevisiae Npa2p (Urb2p) reveals a low-molecular-mass complex containing Dbp6p, Npa1p (Urb1p), Nop8p, and Rsa3p involved in early steps of 60S ribosomal subunit biogenesis. Mol Cell Biol 2007; 27:1207-21. [PMID: 17145778 PMCID: PMC1800719 DOI: 10.1128/mcb.01523-06] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 10/08/2006] [Accepted: 11/24/2006] [Indexed: 11/20/2022] Open
Abstract
We report the characterization of the yeast Npa2p (Urb2p) protein, which is essential for 60S ribosomal subunit biogenesis. We identified this protein in a synthetic lethal screening with the rsa3 null allele. Rsa3p is a genetic partner of the putative RNA helicase Dbp6p. Mutation or depletion of Npa2p leads to a net deficit in 60S subunits and a decrease in the levels all 27S pre-rRNAs and mature 25S and 5.8S rRNAs. This is likely due to instability of early pre-60S particles. Consistent with a role of Npa2p in 60S subunit biogenesis, green fluorescent protein-tagged Npa2p localizes predominantly to the nucleolus and TAP-tagged Npa2p sediments with large complexes in sucrose gradients and is associated mainly with 27SA(2) pre-rRNA-containing preribosomal particles. In addition, we reveal a genetic synthetic interaction between Npa2p, several factors required for early steps of 60S subunit biogenesis (Dbp6p, Dbp7p, Dbp9p, Npa1p, Nop8p, and Rsa3p), and the 60S protein Rpl3p. Furthermore, coimmunoprecipitation and gel filtration analyses demonstrated that at least Npa2p, Dbp6p, Npa1p, Nop8p, and Rsa3p are present together in a subcomplex of low molecular mass whose integrity is independent of RNA. Our results support the idea that these five factors work in concert during the early steps of 60S subunit biogenesis.
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Affiliation(s)
- Iván V Rosado
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes 6, E-41012 Seville, Spain
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10
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Bernstein KA, Granneman S, Lee AV, Manickam S, Baserga SJ. Comprehensive mutational analysis of yeast DEXD/H box RNA helicases involved in large ribosomal subunit biogenesis. Mol Cell Biol 2006; 26:1195-208. [PMID: 16449635 PMCID: PMC1367183 DOI: 10.1128/mcb.26.4.1195-1208.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DEXD/H box putative RNA helicases are required for pre-rRNA processing in Saccharomyces cerevisiae, although their exact roles and substrates are unknown. To characterize the significance of the conserved motifs for helicase function, a series of five mutations were created in each of the eight essential RNA helicases (Has1, Dbp6, Dbp10, Mak5, Mtr4, Drs1, Spb4, and Dbp9) involved in 60S ribosomal subunit biogenesis. Each mutant helicase was screened for the ability to confer dominant negative growth defects and for functional complementation. Different mutations showed different degrees of growth inhibition among the helicases, suggesting that the conserved regions do not function identically in vivo. Mutations in motif I and motif II (the DEXD/H box) often conferred dominant negative growth defects, indicating that these mutations do not interfere with substrate binding. In addition, mutations in the putative unwinding domains (motif III) demonstrated that conserved amino acids are often not essential for function. Northern analysis of steady-state RNA from strains expressing mutant helicases showed that the dominant negative mutations also altered pre-rRNA processing. Coimmunoprecipitation experiments indicated that some RNA helicases associated with each other. In addition, we found that yeasts disrupted in expression of the two nonessential RNA helicases, Dbp3 and Dbp7, grew worse than when either one alone was disrupted.
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Affiliation(s)
- Kara A Bernstein
- Molecular Biophysics & Biochemistry Department, Yale University School of Medicine, 333 Cedar St., SHM C-114, New Haven, CT 06520-8024, USA
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Lebaron S, Froment C, Fromont-Racine M, Rain JC, Monsarrat B, Caizergues-Ferrer M, Henry Y. The splicing ATPase prp43p is a component of multiple preribosomal particles. Mol Cell Biol 2005; 25:9269-82. [PMID: 16227579 PMCID: PMC1265834 DOI: 10.1128/mcb.25.21.9269-9282.2005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prp43p is a putative helicase of the DEAH family which is required for the release of the lariat intron from the spliceosome. Prp43p could also play a role in ribosome synthesis, since it accumulates in the nucleolus. Consistent with this hypothesis, we find that depletion of Prp43p leads to accumulation of 35S pre-rRNA and strongly reduces levels of all downstream pre-rRNA processing intermediates. As a result, the steady-state levels of mature rRNAs are greatly diminished following Prp43p depletion. We present data arguing that such effects are unlikely to be solely due to splicing defects. Moreover, we demonstrate by a combination of a comprehensive two-hybrid screen, tandem-affinity purification followed by mass spectrometry, and Northern analyses that Prp43p is associated with 90S, pre-60S, and pre-40S ribosomal particles. Prp43p seems preferentially associated with Pfa1p, a novel specific component of pre-40S ribosomal particles. In addition, Prp43p interacts with components of the RNA polymerase I (Pol I) transcription machinery and with mature 18S and 25S rRNAs. Hence, Prp43p might be delivered to nascent 90S ribosomal particles during pre-rRNA transcription and remain associated with preribosomal particles until their final maturation steps in the cytoplasm. Our data also suggest that the ATPase activity of Prp43p is required for early steps of pre-rRNA processing and normal accumulation of mature rRNAs.
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Affiliation(s)
- Simon Lebaron
- Laboratoire de Biologie Moléculaire Eucaryote, UMR5099 CNRS-Université Paul Sabatier, IFR109, 118 route de Narbonne, 31062 Toulouse cedex 09, France
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Rosado IV, de la Cruz J. Npa1p is an essential trans-acting factor required for an early step in the assembly of 60S ribosomal subunits in Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2004; 10:1073-83. [PMID: 15208443 PMCID: PMC1370598 DOI: 10.1261/rna.7340404] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2004] [Accepted: 04/05/2004] [Indexed: 05/19/2023]
Abstract
Ribosome biogenesis requires >100 nonribosomal proteins, which are associated with different preribosomal particles. The substrates, the interacting partners, and the timing of action of most of these proteins are largely unknown. To elucidate the functional environment of the putative ATP-dependent RNA helicase Dbp6p from Saccharomyces cerevisiae, which is required for 60S ribosomal subunit assembly, we have previously performed a synthetic lethal screen and thereby revealed a genetic interaction network between Dbp6p, Rpl3p, Nop8p, and the novel Rsa3p. In this report, we extended the characterization of this functional network by performing a synthetic lethal screen with the rsa3 null allele. This screen identified the so far uncharacterized Npa1p (YKL014C). Polysome profile analysis indicates that there is a deficit of 60S ribosomal subunits and an accumulation of halfmer polysomes in the slowly growing npa1-1 mutant. Northern blotting and primer extension analysis shows that the npa1-1 mutation negatively affects processing of all 27S pre-rRNAs and the normal accumulation of both mature 25S and 5.8S rRNAs. In addition, 27SA(2) pre-rRNA is prematurely cleaved at site C(2). Moreover, GFP-tagged Npa1p localizes predominantly to the nucleolus and sediments with large complexes in sucrose gradients, which most likely correspond to pre-60S ribosomal particles. We conclude that Npa1p is required for ribosome biogenesis and operates in the same functional environment of Rsa3p and Dbp6p during early maturation of 60S ribosomal subunits.
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Affiliation(s)
- Ivan V Rosado
- Departamento de Genetica, Facultad de Biologia, Universidad de Sevilla, Avda. Reina Mercedes, 6, E-41012 Sevilla, Spain
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