1
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Bao J, Su B, Chen Z, Sun Z, Peng J, Zhao S. A UTP3-dependent nucleolar translocation pathway facilitates pre-rRNA 5'ETS processing. Nucleic Acids Res 2024:gkae631. [PMID: 39036955 DOI: 10.1093/nar/gkae631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 06/27/2024] [Accepted: 07/09/2024] [Indexed: 07/23/2024] Open
Abstract
The ribosome small subunit (SSU) is assembled by the SSU processome which contains approximately 70 non-ribosomal protein factors. Whilst the biochemical mechanisms of the SSU processome in 18S rRNA processing and maturation have been extensively studied, how SSU processome components enter the nucleolus has yet to be systematically investigated. Here, in examining the nucleolar localization of 50 human SSU processome components, we found that UTP3, together with another 24 proteins, enter the nucleolus autonomously. For the remaining 25 proteins we found that UTP3/SAS10 assists the nucleolar localization of five proteins (MPP10, UTP25, EMG1 and the two UTP-B components UTP12 and UTP13), likely through its interaction with nuclear importin α. This 'ferrying' function of UTP3 was then confirmed as conserved in the zebrafish. We also found that knockdown of human UTP3 impairs cleavage at the A0-site while loss-of-function of either utp3/sas10 or utp13/tbl3 in zebrafish causes the accumulation of aberrantly processed 5'ETS products, which highlights the crucial role of UTP3 in mediating 5'ETS processing. Mechanistically, we found that UTP3 facilitates the degradation of processed 5'ETS by recruiting the RNA exosome component EXOSC10 to the nucleolus. These findings lay the groundwork for studying the mechanism of cytoplasm-to-nucleolus trafficking of SSU processome components.
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Affiliation(s)
- Jiayang Bao
- MOE Key Laboratory for Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Baochun Su
- MOE Key Laboratory for Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Zheyan Chen
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Zhaoxiang Sun
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jinrong Peng
- MOE Key Laboratory for Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Shuyi Zhao
- MOE Key Laboratory for Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
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2
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Martín-Villanueva S, Galmozzi CV, Ruger-Herreros C, Kressler D, de la Cruz J. The Beak of Eukaryotic Ribosomes: Life, Work and Miracles. Biomolecules 2024; 14:882. [PMID: 39062596 PMCID: PMC11274626 DOI: 10.3390/biom14070882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Revised: 07/19/2024] [Accepted: 07/21/2024] [Indexed: 07/28/2024] Open
Abstract
Ribosomes are not totally globular machines. Instead, they comprise prominent structural protrusions and a myriad of tentacle-like projections, which are frequently made up of ribosomal RNA expansion segments and N- or C-terminal extensions of ribosomal proteins. This is more evident in higher eukaryotic ribosomes. One of the most characteristic protrusions, present in small ribosomal subunits in all three domains of life, is the so-called beak, which is relevant for the function and regulation of the ribosome's activities. During evolution, the beak has transitioned from an all ribosomal RNA structure (helix h33 in 16S rRNA) in bacteria, to an arrangement formed by three ribosomal proteins, eS10, eS12 and eS31, and a smaller h33 ribosomal RNA in eukaryotes. In this review, we describe the different structural and functional properties of the eukaryotic beak. We discuss the state-of-the-art concerning its composition and functional significance, including other processes apparently not related to translation, and the dynamics of its assembly in yeast and human cells. Moreover, we outline the current view about the relevance of the beak's components in human diseases, especially in ribosomopathies and cancer.
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Affiliation(s)
- Sara Martín-Villanueva
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, E-41013 Seville, Spain; (S.M.-V.); (C.V.G.); (C.R.-H.)
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, E-41012 Seville, Spain
| | - Carla V. Galmozzi
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, E-41013 Seville, Spain; (S.M.-V.); (C.V.G.); (C.R.-H.)
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, E-41012 Seville, Spain
| | - Carmen Ruger-Herreros
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, E-41013 Seville, Spain; (S.M.-V.); (C.V.G.); (C.R.-H.)
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, E-41012 Seville, Spain
| | - Dieter Kressler
- Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland;
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, E-41013 Seville, Spain; (S.M.-V.); (C.V.G.); (C.R.-H.)
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, E-41012 Seville, Spain
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3
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Beine-Golovchuk O, Kallas M, Kunze R, Griesel S, Baßler J. The Efg1-Bud22 dimer associates with the U14 snoRNP contacting the 5' rRNA domain of an early 90S pre-ribosomal particle. Nucleic Acids Res 2024; 52:431-447. [PMID: 38000371 PMCID: PMC10783500 DOI: 10.1093/nar/gkad1109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
The DEAD-box helicase Dbp4 plays an essential role during the early assembly of the 40S ribosome, which is only poorly understood to date. By applying the yeast two-hybrid method and biochemical approaches, we discovered that Dbp4 interacts with the Efg1-Bud22 dimer. Both factors associate with early pre-90S particles and smaller complexes, each characterized by a high presence of the U14 snoRNA. A crosslink analysis of Bud22 revealed its contact to the U14 snoRNA and the 5' domain of the nascent 18S rRNA, close to its U14 snoRNA hybridization site. Moreover, depletion of Bud22 or Efg1 specifically affects U14 snoRNA association with pre-ribosomal complexes. Accordingly, we concluded that the role of the Efg1-Bud22 dimer is linked to the U14 snoRNA function on early 90S ribosome intermediates chaperoning the 5' domain of the nascent 18S rRNA. The successful rRNA folding of the 5' domain and the release of Efg1, Bud22, Dpb4, U14 snoRNA and associated snoRNP factors allows the subsequent recruitment of the Kre33-Bfr2-Enp2-Lcp5 module towards the 90S pre-ribosome.
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Affiliation(s)
- Olga Beine-Golovchuk
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Martina Kallas
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Ruth Kunze
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Sabine Griesel
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Jochen Baßler
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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4
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LaPeruta AJ, Micic J, Woolford Jr. JL. Additional principles that govern the release of pre-ribosomes from the nucleolus into the nucleoplasm in yeast. Nucleic Acids Res 2023; 51:10867-10883. [PMID: 35736211 PMCID: PMC10639060 DOI: 10.1093/nar/gkac430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 05/05/2022] [Accepted: 06/20/2022] [Indexed: 11/14/2022] Open
Abstract
During eukaryotic ribosome biogenesis, pre-ribosomes travel from the nucleolus, where assembly is initiated, to the nucleoplasm and then are exported to the cytoplasm, where assembly concludes. Although nuclear export of pre-ribosomes has been extensively investigated, the release of pre-ribosomes from the nucleolus is an understudied phenomenon. Initial data indicate that unfolded rRNA interacts in trans with nucleolar components and that, when rRNA folds due to ribosomal protein (RP) binding, the number of trans interactions drops below the threshold necessary for nucleolar retention. To validate and expand on this idea, we performed a bioinformatic analysis of the protein components of the Saccharomyces cerevisiae ribosome assembly pathway. We found that ribosome biogenesis factors (RiBi factors) contain significantly more predicted trans interacting regions than RPs. We also analyzed cryo-EM structures of ribosome assembly intermediates to determine how nucleolar pre-ribosomes differ from post-nucleolar pre-ribosomes, specifically the capacity of RPs, RiBi factors, and rRNA components to interact in trans. We observed a significant decrease in the theoretical trans-interacting capability of pre-ribosomes between nucleolar and post-nucleolar stages of assembly due to the release of RiBi factors from particles and the folding of rRNA. Here, we provide a mechanism for the release of pre-ribosomes from the nucleolus.
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Affiliation(s)
- Amber J LaPeruta
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Jelena Micic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - John L Woolford Jr.
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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5
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Zhang Y, Liang X, Luo S, Chen Y, Li Y, Ma C, Li N, Gao N. Visualizing the nucleoplasmic maturation of human pre-60S ribosomal particles. Cell Res 2023; 33:867-878. [PMID: 37491604 PMCID: PMC10624882 DOI: 10.1038/s41422-023-00853-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 07/07/2023] [Indexed: 07/27/2023] Open
Abstract
Eukaryotic ribosome assembly is a highly orchestrated process that involves over two hundred protein factors. After early assembly events on nascent rRNA in the nucleolus, pre-60S particles undergo continuous maturation steps in the nucleoplasm, and prepare for nuclear export. Here, we report eleven cryo-EM structures of the nuclear pre-60S particles isolated from human cells through epitope-tagged GNL2, at resolutions of 2.8-4.3 Å. These high-resolution snapshots provide fine details for several major structural remodeling events at a virtual temporal resolution. Two new human nuclear factors, L10K and C11orf98, were also identified. Comparative structural analyses reveal that many assembly factors act as successive place holders to control the timing of factor association/dissociation events. They display multi-phasic binding properties for different domains and generate complex binding inter-dependencies as a means to guide the rRNA maturation process towards its mature conformation. Overall, our data reveal that nuclear assembly of human pre-60S particles is generally hierarchical with short branch pathways, and a few factors display specific roles as rRNA chaperones by confining rRNA helices locally to facilitate their folding, such as the C-terminal domain of SDAD1.
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Affiliation(s)
- Yunyang Zhang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Xiaomeng Liang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Sha Luo
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Yan Chen
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Yu Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Chengying Ma
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- Changping Laboratory, Beijing, China
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- Changping Laboratory, Beijing, China
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
- Changping Laboratory, Beijing, China.
- National Biomedical Imaging Center, Peking University, Beijing, China.
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6
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Blomqvist EK, Huang H, Karbstein K. A disease associated mutant reveals how Ltv1 orchestrates RP assembly and rRNA folding of the small ribosomal subunit head. PLoS Genet 2023; 19:e1010862. [PMID: 37910572 PMCID: PMC10695388 DOI: 10.1371/journal.pgen.1010862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 12/04/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
Ribosomes are complex macromolecules assembled from 4 rRNAs and 79 ribosomal proteins (RPs). Their assembly is organized in a highly hierarchical manner, which is thought to avoid dead-end pathways, thereby enabling efficient assembly of ribosomes in the large quantities needed for healthy cellular growth. Moreover, hierarchical assembly also can help ensure that each RP is included in the mature ribosome. Nonetheless, how this hierarchy is achieved remains unknown, beyond the examples that depend on direct RP-RP interactions, which account for only a fraction of the observed dependencies. Using assembly of the small subunit head and a disease-associated mutation in the assembly factor Ltv1 as a model system, we dissect here how the hierarchy in RP binding is constructed. A combination of data from yeast genetics, mass spectrometry, DMS probing and biochemical experiments demonstrate that the LIPHAK-disease-associated Ltv1 mutation leads to global defects in head assembly, which are explained by direct binding of Ltv1 to 5 out of 15 RPs, and indirect effects that affect 4 additional RPs. These indirect effects are mediated by conformational transitions in the nascent subunit that are regulated by Ltv1. Mechanistically, Ltv1 aids the recruitment of some RPs via direct protein-protein interactions, but surprisingly also delays the recruitment of other RPs. Delayed binding of key RPs also delays the acquisition of RNA structure that is stabilized by these proteins. Finally, our data also indicate direct roles for Ltv1 in chaperoning the folding of a key rRNA structural element, the three-helix junction j34-35-38. Thus, Ltv1 plays critical roles in organizing the order of both RP binding to rRNA and rRNA folding, thereby enabling efficient 40S subunit assembly.
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Affiliation(s)
- Ebba K. Blomqvist
- Department of Integrative Structural and Computational Biology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, Florida, United States of America
| | - Haina Huang
- Department of Integrative Structural and Computational Biology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, Florida, United States of America
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, California, United States of America
| | - Katrin Karbstein
- Department of Integrative Structural and Computational Biology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, Florida, United States of America
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, California, United States of America
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7
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Bohnsack KE, Yi S, Venus S, Jankowsky E, Bohnsack MT. Cellular functions of eukaryotic RNA helicases and their links to human diseases. Nat Rev Mol Cell Biol 2023; 24:749-769. [PMID: 37474727 DOI: 10.1038/s41580-023-00628-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/22/2023]
Abstract
RNA helicases are highly conserved proteins that use nucleoside triphosphates to bind or remodel RNA, RNA-protein complexes or both. RNA helicases are classified into the DEAD-box, DEAH/RHA, Ski2-like, Upf1-like and RIG-I families, and are the largest class of enzymes active in eukaryotic RNA metabolism - virtually all aspects of gene expression and its regulation involve RNA helicases. Mutation and dysregulation of these enzymes have been linked to a multitude of diseases, including cancer and neurological disorders. In this Review, we discuss the regulation and functional mechanisms of RNA helicases and their roles in eukaryotic RNA metabolism, including in transcription regulation, pre-mRNA splicing, ribosome assembly, translation and RNA decay. We highlight intriguing models that link helicase structure, mechanisms of function (such as local strand unwinding, translocation, winching, RNA clamping and displacing RNA-binding proteins) and biological roles, including emerging connections between RNA helicases and cellular condensates formed through liquid-liquid phase separation. We also discuss associations of RNA helicases with human diseases and recent efforts towards the design of small-molecule inhibitors of these pivotal regulators of eukaryotic gene expression.
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Affiliation(s)
- Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
| | - Soon Yi
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Sarah Venus
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Eckhard Jankowsky
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Moderna, Cambridge, MA, USA.
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
- Göttingen Centre for Molecular Biosciences, University of Göttingen, Göttingen, Germany.
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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8
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Yang X, Shu Y, Cao S, Sun H, Zhang X, Zhang A, Li Y, Ma D, Chen H, Li W. Trehalase Inhibitor Validamycin May Have Additional Mechanisms of Toxicology against Rhizoctonia cerealis. J Fungi (Basel) 2023; 9:846. [PMID: 37623617 PMCID: PMC10455246 DOI: 10.3390/jof9080846] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/09/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023] Open
Abstract
Sharp eyespot is a crucial disease affecting cereal plants, such as bread wheat (Triticum aestivum) and barley (Hordeum vulgare), and is primarily caused by the pathogenic fungus Rhizoctonia cerealis. As disease severity has increased, it has become imperative to find an effective and reasonable control strategy. One such strategy is the use of the trehalose analog, validamycin, which has been shown to have a potent inhibitory effect on several trehalases found in both insects and fungi, and is widely used as a fungicide in agriculture. In this study, we demonstrated that 0.5 μg/mL validamycin on PDA plates had an inhibitory effect on R. cerealis strain R0301, but had no significant impact on Fusarium graminearum strain PH-1. Except for its inhibiting the trehalase activity of pathogenic fungi, little is known about its mechanism of action. Six trehalase genes were identified in the genome of R. cerealis, including one neutral trehalase and five acidic trehalase genes. Enzyme activity assays indicated that treatment with 5 μg/mL validamycin significantly reduces trehalase activity, providing evidence that validamycin treatment does indeed affect trehalase, even though the expression levels of most trehalase genes, except Rc17406, were not obviously affected. Transcriptome analysis revealed that treatment with validamycin downregulated genes involved in metabolic processes, ribosome biogenesis, and pathogenicity in the R. cerealis. KEGG pathway analysis further showed that validamycin affected genes related to the MAPK signaling pathway, with a significant decrease in ribosome synthesis and assembly. In conclusion, our results indicated that validamycin not only inhibits trehalose activity, but also affects the ribosome synthesis and MAPK pathways of R. cerealis, leading to the suppression of fungal growth and pesticidal effects. This study provides novel insights into the mechanism of action of validamycin.
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Affiliation(s)
- Xiaoyue Yang
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
- Key Laboratory of Sustainable Crop Production in the Middle Reaches of the Yangtze River, College of Agriculture, Yangtze University, Jingzhou 434025, China
| | - Yan Shu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Shulin Cao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Haiyan Sun
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xin Zhang
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Aixiang Zhang
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Yan Li
- Key Laboratory of Sustainable Crop Production in the Middle Reaches of the Yangtze River, College of Agriculture, Yangtze University, Jingzhou 434025, China
| | - Dongfang Ma
- Key Laboratory of Sustainable Crop Production in the Middle Reaches of the Yangtze River, College of Agriculture, Yangtze University, Jingzhou 434025, China
| | - Huaigu Chen
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
- Jiangsu Co-Innovation Centre for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China
| | - Wei Li
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
- Jiangsu Co-Innovation Centre for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China
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9
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Khreiss A, Bohnsack KE, Bohnsack MT. Molecular functions of RNA helicases during ribosomal subunit assembly. Biol Chem 2023; 404:781-789. [PMID: 37233600 DOI: 10.1515/hsz-2023-0135] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/09/2023] [Indexed: 05/27/2023]
Abstract
During their biogenesis, the ribosomal subunits undergo numerous structural and compositional changes to achieve their final architecture. RNA helicases are a key driving force of such remodelling events but deciphering their particular functions has long been challenging due to lack of knowledge of their molecular functions and RNA substrates. Advances in the biochemical characterisation of RNA helicase activities together with new insights into RNA helicase binding sites on pre-ribosomes and structural snapshots of pre-ribosomal complexes containing RNA helicases now open the door to a deeper understanding of precisely how different RNA helicases contribute to ribosomal subunit maturation.
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Affiliation(s)
- Ali Khreiss
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
- Göttingen Centre for Molecular Biosciences, Georg-August University, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany
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10
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Blomqvist EK, Huang H, Karbstein K. A disease associated mutant reveals how Ltv1 orchestrates RP assembly and rRNA folding of the small ribosomal subunit head. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548325. [PMID: 37503067 PMCID: PMC10369890 DOI: 10.1101/2023.07.10.548325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Ribosomes are complex macromolecules assembled from 4 rRNAs and 79 ribosomal proteins (RPs). Their assembly is organized in a highly hierarchical manner, which is thought to avoid dead-end pathways, thereby enabling efficient assembly of ribosomes in the large quantities needed for healthy cellular growth. Moreover, hierarchical assembly also can help ensure that each RP is included in the mature ribosome. Nonetheless, how this hierarchy is achieved remains unknown, beyond the examples that depend on direct RP-RP interactions, which account for only a fraction of the observed dependencies. Using assembly of the small subunit head and a disease-associated mutation in the assembly factor Ltv1 as a model system, we dissect here how the hierarchy in RP binding is constructed. Our data demonstrate that the LIPHAK-disease-associated Ltv1 mutation leads to global defects in head assembly, which are explained by direct binding of Ltv1 to 5 out of 15 RPs, and indirect effects that affect 4 additional RPs. These indirect effects are mediated by conformational transitions in the nascent subunit that are regulated by Ltv1. Mechanistically, Ltv1 aids the recruitment of some RPs via direct protein-protein interactions, but surprisingly also delays the recruitment of other RPs. Delayed binding of key RPs also delays the acquisition of RNA structure that is stabilized by these proteins. Finally, our data also indicate direct roles for Ltv1 in chaperoning the folding of a key rRNA structural element, the three-helix junction j34-35-38. Thus, Ltv1 plays critical roles in organizing the order of both RP binding to rRNA and rRNA folding, thereby enabling efficient 40S subunit assembly.
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Affiliation(s)
- Ebba K. Blomqvist
- Department of Integrative Structural and Computational Biology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, Florida 33458, United States of America
| | - Haina Huang
- Department of Integrative Structural and Computational Biology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, Florida 33458, United States of America
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA 92037
- Present Address: Arrakis Therapeutics, Waltham, MA 02451
| | - Katrin Karbstein
- Department of Integrative Structural and Computational Biology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, Florida 33458, United States of America
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA 92037
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11
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Lau B, Huang Z, Kellner N, Niu S, Berninghausen O, Beckmann R, Hurt E, Cheng J. Mechanism of 5S RNP recruitment and helicase-surveilled rRNA maturation during pre-60S biogenesis. EMBO Rep 2023; 24:e56910. [PMID: 37129998 PMCID: PMC10328080 DOI: 10.15252/embr.202356910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 05/03/2023] Open
Abstract
Ribosome biogenesis proceeds along a multifaceted pathway from the nucleolus to the cytoplasm that is extensively coupled to several quality control mechanisms. However, the mode by which 5S ribosomal RNA is incorporated into the developing pre-60S ribosome, which in humans links ribosome biogenesis to cell proliferation by surveillance by factors such as p53-MDM2, is poorly understood. Here, we report nine nucleolar pre-60S cryo-EM structures from Chaetomium thermophilum, one of which clarifies the mechanism of 5S RNP incorporation into the early pre-60S. Successive assembly states then represent how helicases Dbp10 and Spb4, and the Pumilio domain factor Puf6 act in series to surveil the gradual folding of the nearby 25S rRNA domain IV. Finally, the methyltransferase Spb1 methylates a universally conserved guanine nucleotide in the A-loop of the peptidyl transferase center, thereby licensing further maturation. Our findings provide insight into the hierarchical action of helicases in safeguarding rRNA tertiary structure folding and coupling to surveillance mechanisms that culminate in local RNA modification.
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Affiliation(s)
- Benjamin Lau
- Heidelberg University Biochemistry Center (BZH)HeidelbergGermany
| | - Zixuan Huang
- Minhang Hospital & Institutes of Biomedical Sciences, Shanghai Key Laboratory of Medical Epigenetics, International Co‐laboratory of Medical Epigenetics and MetabolismFudan UniversityShanghaiChina
| | - Nikola Kellner
- Heidelberg University Biochemistry Center (BZH)HeidelbergGermany
| | | | | | - Roland Beckmann
- Gene CenterLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH)HeidelbergGermany
| | - Jingdong Cheng
- Minhang Hospital & Institutes of Biomedical Sciences, Shanghai Key Laboratory of Medical Epigenetics, International Co‐laboratory of Medical Epigenetics and MetabolismFudan UniversityShanghaiChina
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12
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Schneider C, Bohnsack KE. Caught in the act-Visualizing ribonucleases during eukaryotic ribosome assembly. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1766. [PMID: 36254602 DOI: 10.1002/wrna.1766] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/22/2022] [Accepted: 09/24/2022] [Indexed: 07/20/2023]
Abstract
Ribosomes are essential macromolecular machines responsible for translating the genetic information encoded in mRNAs into proteins. Ribosomes are composed of ribosomal RNAs and proteins (rRNAs and RPs) and the rRNAs fulfill both catalytic and architectural functions. Excision of the mature eukaryotic rRNAs from their precursor transcript is achieved through a complex series of endoribonucleolytic cleavages and exoribonucleolytic processing steps that are precisely coordinated with other aspects of ribosome assembly. Many ribonucleases involved in pre-rRNA processing have been identified and pre-rRNA processing pathways are relatively well defined. However, momentous advances in cryo-electron microscopy have recently enabled structural snapshots of various pre-ribosomal particles from budding yeast (Saccharomyces cerevisiae) and human cells to be captured and, excitingly, these structures not only allow pre-rRNAs to be observed before and after cleavage events, but also enable ribonucleases to be visualized on their target RNAs. These structural views of pre-rRNA processing in action allow a new layer of understanding of rRNA maturation and how it is coordinated with other aspects of ribosome assembly. They illuminate mechanisms of target recognition by the diverse ribonucleases involved and reveal how the cleavage/processing activities of these enzymes are regulated. In this review, we discuss the new insights into pre-rRNA processing gained by structural analyses and the growing understanding of the mechanisms of ribonuclease regulation. This article is categorized under: Translation > Ribosome Biogenesis RNA Processing > rRNA Processing.
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Affiliation(s)
- Claudia Schneider
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
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13
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Parker MD, Karbstein K. Quality control ensures fidelity in ribosome assembly and cellular health. J Cell Biol 2023; 222:213871. [PMID: 36790396 PMCID: PMC9960125 DOI: 10.1083/jcb.202209115] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/09/2023] [Accepted: 02/02/2023] [Indexed: 02/16/2023] Open
Abstract
The coordinated integration of ribosomal RNA and protein into two functional ribosomal subunits is safeguarded by quality control checkpoints that ensure ribosomes are correctly assembled and functional before they engage in translation. Quality control is critical in maintaining the integrity of ribosomes and necessary to support healthy cell growth and prevent diseases associated with mistakes in ribosome assembly. Its importance is demonstrated by the finding that bypassing quality control leads to misassembled, malfunctioning ribosomes with altered translation fidelity, which change gene expression and disrupt protein homeostasis. In this review, we outline our understanding of quality control within ribosome synthesis and how failure to enforce quality control contributes to human disease. We first provide a definition of quality control to guide our investigation, briefly present the main assembly steps, and then examine stages of assembly that test ribosome function, establish a pass-fail system to evaluate these functions, and contribute to altered ribosome performance when bypassed, and are thus considered "quality control."
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Affiliation(s)
- Melissa D. Parker
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA, USA,University of Florida—Scripps Biomedical Research, Jupiter, FL, USA
| | - Katrin Karbstein
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA, USA,University of Florida—Scripps Biomedical Research, Jupiter, FL, USA,Howard Hughes Medical Institute Faculty Scholar, Howard Hughes Medical Institute, Chevy Chase, MD, USA,Correspondence to Katrin Karbstein:
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14
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Dörner K, Ruggeri C, Zemp I, Kutay U. Ribosome biogenesis factors-from names to functions. EMBO J 2023; 42:e112699. [PMID: 36762427 PMCID: PMC10068337 DOI: 10.15252/embj.2022112699] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/13/2022] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
The assembly of ribosomal subunits is a highly orchestrated process that involves a huge cohort of accessory factors. Most eukaryotic ribosome biogenesis factors were first identified by genetic screens and proteomic approaches of pre-ribosomal particles in Saccharomyces cerevisiae. Later, research on human ribosome synthesis not only demonstrated that the requirement for many of these factors is conserved in evolution, but also revealed the involvement of additional players, reflecting a more complex assembly pathway in mammalian cells. Yet, it remained a challenge for the field to assign a function to many of the identified factors and to reveal their molecular mode of action. Over the past decade, structural, biochemical, and cellular studies have largely filled this gap in knowledge and led to a detailed understanding of the molecular role that many of the players have during the stepwise process of ribosome maturation. Such detailed knowledge of the function of ribosome biogenesis factors will be key to further understand and better treat diseases linked to disturbed ribosome assembly, including ribosomopathies, as well as different types of cancer.
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Affiliation(s)
- Kerstin Dörner
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,Molecular Life Sciences Ph.D. Program, Zurich, Switzerland
| | - Chiara Ruggeri
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,RNA Biology Ph.D. Program, Zurich, Switzerland
| | - Ivo Zemp
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Ulrike Kutay
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
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15
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Guerra-Slompo E, Cesaro G, Guimarães B, Zanchin N. Dissecting Trypanosoma brucei RRP44 function in the maturation of segmented ribosomal RNA using a regulated genetic complementation system. Nucleic Acids Res 2023; 51:396-419. [PMID: 36610751 PMCID: PMC9841430 DOI: 10.1093/nar/gkac1217] [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: 02/14/2022] [Revised: 11/29/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023] Open
Abstract
Trypanosoma brucei belongs to a group of protozoans presenting fragmented large subunit rRNA. Its LSU rRNA equivalent to the 25S/28S rRNA of other eukaryotes is split into six fragments, requiring additional processing for removal of the extra spacer sequences. We have used a genetic complementation strategy to further investigate the T. brucei RRP44 nuclease in pre-rRNA maturation. TbRRP44 contains both a PIN and a RNB domain whose homologues are found in association with the exosome complex. We found that the exonucleolytic activity of the RNB domain as well as the physical presence of the PIN domain are essential for TbRRP44 function, while a catalytic site mutation in the PIN domain has no detectable effect on cell growth. A new endonucleolytic cleavage site in ITS1 was identified. In addition to the 5.8S rRNA 3'-end maturation, TbRRP44 is required for degradation of the excised 5'-ETS and for removal of part of ITS1 during maturation of the 18S rRNA 3'-end. TbRRP44 deficiency leads to accumulation of many LSU intermediate precursors, most of them not detected in control cells. TbRRP44 is also required for U3 snoRNA and spliced leader processing, indicating that TbRRP44 may have a wide role in RNA processing in T. brucei.
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Affiliation(s)
- Eloise Pavão Guerra-Slompo
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ, R. Prof. Algacyr Munhoz Mader 3775, 81350-010, Curitiba-PR, Brazil
| | - Giovanna Cesaro
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ, R. Prof. Algacyr Munhoz Mader 3775, 81350-010, Curitiba-PR, Brazil,Biochemistry Postgraduate Program, Federal University of Paraná, Curitiba-PR, Brazil
| | - Beatriz Gomes Guimarães
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ, R. Prof. Algacyr Munhoz Mader 3775, 81350-010, Curitiba-PR, Brazil,Biochemistry Postgraduate Program, Federal University of Paraná, Curitiba-PR, Brazil
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16
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Lau B, Beine-Golovchuk O, Kornprobst M, Cheng J, Kressler D, Jády B, Kiss T, Beckmann R, Hurt E. Cms1 coordinates stepwise local 90S pre-ribosome assembly with timely snR83 release. Cell Rep 2022; 41:111684. [PMID: 36417864 PMCID: PMC9715914 DOI: 10.1016/j.celrep.2022.111684] [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: 03/24/2022] [Revised: 08/01/2022] [Accepted: 10/27/2022] [Indexed: 11/23/2022] Open
Abstract
Ribosome synthesis begins in the nucleolus with 90S pre-ribosome construction, but little is known about how the many different snoRNAs that modify the pre-rRNA are timely guided to their target sites. Here, we report a role for Cms1 in such a process. Initially, we discovered CMS1 as a null suppressor of a nop14 mutant impaired in Rrp12-Enp1 factor recruitment to the 90S. Further investigations detected Cms1 at the 18S rRNA 3' major domain of an early 90S that carried H/ACA snR83, which is known to guide pseudouridylation at two target sites within the same subdomain. Cms1 co-precipitates with many 90S factors, but Rrp12-Enp1 encircling the 3' major domain in the mature 90S is decreased. We suggest that Cms1 associates with the 3' major domain during early 90S biogenesis to restrict premature Rrp12-Enp1 binding but allows snR83 to timely perform its modification role before the next 90S assembly steps coupled with Cms1 release take place.
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Affiliation(s)
- Benjamin Lau
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Olga Beine-Golovchuk
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Markus Kornprobst
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Jingdong Cheng
- Institutes of Biomedical Sciences, Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Fudan University, Dong’an Road 131, Shanghai 200032, China
| | - Dieter Kressler
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Beáta Jády
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Tamás Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Roland Beckmann
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany,Corresponding author
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany,Corresponding author
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17
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Cheng J, Lau B, Thoms M, Ameismeier M, Berninghausen O, Hurt E, Beckmann R. The nucleoplasmic phase of pre-40S formation prior to nuclear export. Nucleic Acids Res 2022; 50:11924-11937. [PMID: 36321656 PMCID: PMC9723619 DOI: 10.1093/nar/gkac961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/04/2022] [Accepted: 10/21/2022] [Indexed: 11/07/2022] Open
Abstract
Biogenesis of the small ribosomal subunit in eukaryotes starts in the nucleolus with the formation of a 90S precursor and ends in the cytoplasm. Here, we elucidate the enigmatic structural transitions of assembly intermediates from human and yeast cells during the nucleoplasmic maturation phase. After dissociation of all 90S factors, the 40S body adopts a close-to-mature conformation, whereas the 3' major domain, later forming the 40S head, remains entirely immature. A first coordination is facilitated by the assembly factors TSR1 and BUD23-TRMT112, followed by re-positioning of RRP12 that is already recruited early to the 90S for further head rearrangements. Eventually, the uS2 cluster, CK1 (Hrr25 in yeast) and the export factor SLX9 associate with the pre-40S to provide export competence. These exemplary findings reveal the evolutionary conserved mechanism of how yeast and humans assemble the 40S ribosomal subunit, but reveal also a few minor differences.
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Affiliation(s)
- Jingdong Cheng
- Gene Center and Department of Biochemistry, University of Munich LMU, Feodor-Lynen-Str. 25, 81377 Munich, Germany,Institutes of Biomedical Sciences, Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Fudan University, Dong’an Road 131, 200032 Shanghai, China
| | - Benjamin Lau
- BZH, University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Matthias Thoms
- Gene Center and Department of Biochemistry, University of Munich LMU, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Michael Ameismeier
- Gene Center and Department of Biochemistry, University of Munich LMU, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Otto Berninghausen
- Gene Center and Department of Biochemistry, University of Munich LMU, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Ed Hurt
- Correspondence may also be addressed to Ed Hurt.
| | - Roland Beckmann
- To whom correspondence should be addressed. Tel: +49 89 218076900; Fax: +49 89 218076945;
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18
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Cheng J, La Venuta G, Lau B, Berninghausen O, Beckmann R, Hurt E. In vitro structural maturation of an early stage pre-40S particle coupled with U3 snoRNA release and central pseudoknot formation. Nucleic Acids Res 2022; 50:11916-11923. [PMID: 36263816 PMCID: PMC9723636 DOI: 10.1093/nar/gkac910] [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: 07/26/2022] [Revised: 09/28/2022] [Accepted: 10/18/2022] [Indexed: 12/24/2022] Open
Abstract
The transition of the 90S to the pre-40S pre-ribosome is a decisive step in eukaryotic small subunit biogenesis leading to a first pre-40S intermediate (state Dis-C or primordial pre-40S), where the U3 snoRNA keeps the nascent 18S rRNA locally immature. We in vitro reconstitute the ATP-dependent U3 release from this particle, catalyzed by the helicase Dhr1, and follow this process by cryo-EM revealing two successive pre-40S intermediates, Dis-D and Dis-E. The latter has lost not only U3 but all residual 90S factors including the GTPase Bms1. In vitro remodeling likewise induced the formation of the central pseudoknot, a universally conserved tertiary RNA structure that comprises the core of the small subunit decoding center. Thus, we could structurally reveal a key tertiary RNA folding step that is essential to form the active 40S subunit.
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Affiliation(s)
| | | | | | - Otto Berninghausen
- Gene Center and Department of Biochemistry, University of Munich LMU, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | | | - Ed Hurt
- To whom correspondence should be addressed. Tel: +49 6221 54 41 73;
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19
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Bohnsack KE, Kanwal N, Bohnsack MT. Prp43/DHX15 exemplify RNA helicase multifunctionality in the gene expression network. Nucleic Acids Res 2022; 50:9012-9022. [PMID: 35993807 PMCID: PMC9458436 DOI: 10.1093/nar/gkac687] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/10/2022] [Accepted: 08/01/2022] [Indexed: 12/24/2022] Open
Abstract
Dynamic regulation of RNA folding and structure is critical for the biogenesis and function of RNAs and ribonucleoprotein (RNP) complexes. Through their nucleotide triphosphate-dependent remodelling functions, RNA helicases are key modulators of RNA/RNP structure. While some RNA helicases are dedicated to a specific target RNA, others are multifunctional and engage numerous substrate RNAs in different aspects of RNA metabolism. The discovery of such multitasking RNA helicases raises the intriguing question of how these enzymes can act on diverse RNAs but also maintain specificity for their particular targets within the RNA-dense cellular environment. Furthermore, the identification of RNA helicases that sit at the nexus between different aspects of RNA metabolism raises the possibility that they mediate cross-regulation of different cellular processes. Prominent and extensively characterized multifunctional DEAH/RHA-box RNA helicases are DHX15 and its Saccharomyces cerevisiae (yeast) homologue Prp43. Due to their central roles in key cellular processes, these enzymes have also served as prototypes for mechanistic studies elucidating the mode of action of this type of enzyme. Here, we summarize the current knowledge on the structure, regulation and cellular functions of Prp43/DHX15, and discuss the general concept and implications of RNA helicase multifunctionality.
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Affiliation(s)
- Katherine E Bohnsack
- Correspondence may also be addressed to Katherine E. Bohnsack. Tel: +49 551 3969305; Fax: +49 551 395960;
| | - Nidhi Kanwal
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Markus T Bohnsack
- To whom correspondence should be addressed. Tel: +49 551 395968; Fax: +49 551 395960;
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20
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Lin S, Rajan S, Lemberg S, Altawil M, Anderson K, Bryant R, Cappeta S, Chin B, Hamdan I, Hamer A, Hyzny R, Karp A, Lee D, Lim A, Nayak M, Palaniappan V, Park S, Satishkumar S, Seth A, Sri Dasari U, Toppari E, Vyas A, Walker J, Weston E, Zafar A, Zielke C, Mahabeleshwar GH, Tartakoff AM. Production of nascent ribosome precursors within the nucleolar microenvironment of Saccharomyces cerevisiae. Genetics 2022; 221:iyac070. [PMID: 35657327 PMCID: PMC9252279 DOI: 10.1093/genetics/iyac070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
35S rRNA transcripts include a 5'-external transcribed spacer followed by rRNAs of the small and large ribosomal subunits. Their processing yields massive precursors that include dozens of assembly factor proteins. In Saccharomyces cerevisiae, nucleolar assembly factors form 2 coaxial layers/volumes around ribosomal DNA. Most of these factors are cyclically recruited from a latent state to an operative state, and are extensively conserved. The layers match, at least approximately, known subcompartments found in higher eukaryotic cells. ∼80% of assembly factors are essential. The number of copies of these assembly factors is comparable to the number of nascent transcripts. Moreover, they exhibit "isoelectric balance," with RNA-binding candidate "nucleator" assembly factors being notably basic. The physical properties of pre-small subunit and pre-large subunit assembly factors are similar, as are their 19 motif signatures detected by hierarchical clustering, unlike motif signatures of the 5'-external transcribed spacer rRNP. Additionally, many assembly factors lack shared motifs. Taken together with the progression of rRNP composition during subunit maturation, and the realization that the ribosomal DNA cable is initially bathed in a subunit-nonspecific assembly factor reservoir/microenvironment, we propose a "3-step subdomain assembly model": Step (1): predominantly basic assembly factors sequentially nucleate sites along nascent rRNA; Step (2): the resulting rRNPs recruit numerous less basic assembly factors along with notably basic ribosomal proteins; Step (3): rRNPs in nearby subdomains consolidate. Cleavages of rRNA then promote release of rRNPs to the nucleoplasm, likely facilitated by the persistence of assembly factors that were already associated with nucleolar precursors.
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Affiliation(s)
- Samantha Lin
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Suchita Rajan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sofia Lemberg
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark Altawil
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Katherine Anderson
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ruth Bryant
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sebastian Cappeta
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Brandon Chin
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Isabella Hamdan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Annelise Hamer
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Rachel Hyzny
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Andrew Karp
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Daniel Lee
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Alexandria Lim
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Medha Nayak
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Vishnu Palaniappan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Soomin Park
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sarika Satishkumar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Anika Seth
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Uva Sri Dasari
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Emili Toppari
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ayush Vyas
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Julianne Walker
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Evan Weston
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Atif Zafar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Cecelia Zielke
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ganapati H Mahabeleshwar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Alan M Tartakoff
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
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21
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Oborská-Oplová M, Gerhardy S, Panse VG. Orchestrating ribosomal RNA folding during ribosome assembly. Bioessays 2022; 44:e2200066. [PMID: 35751450 DOI: 10.1002/bies.202200066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/30/2022] [Accepted: 06/13/2022] [Indexed: 11/08/2022]
Abstract
Construction of the eukaryotic ribosome is a complex process in which a nascent ribosomal RNA (rRNA) emerging from RNA Polymerase I hierarchically folds into a native three-dimensional structure. Modular assembly of individual RNA domains through interactions with ribosomal proteins and a myriad of assembly factors permit efficient disentanglement of the error-prone RNA folding process. Following these dynamic events, long-range tertiary interactions are orchestrated to compact rRNA. A combination of genetic, biochemical, and structural studies is now providing clues into how a nascent rRNA is transformed into a functional ribosome with high precision. With this essay, we aim to draw attention to the poorly understood process of establishing correct RNA tertiary contacts during ribosome formation.
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Affiliation(s)
| | - Stefan Gerhardy
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Vikram Govind Panse
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.,Faculty of Science, University of Zurich, Zurich, Switzerland
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22
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Itoh Y, Khawaja A, Laptev I, Cipullo M, Atanassov I, Sergiev P, Rorbach J, Amunts A. Mechanism of mitoribosomal small subunit biogenesis and preinitiation. Nature 2022; 606:603-608. [PMID: 35676484 PMCID: PMC9200640 DOI: 10.1038/s41586-022-04795-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 04/22/2022] [Indexed: 12/27/2022]
Abstract
Mitoribosomes are essential for the synthesis and maintenance of bioenergetic proteins. Here we use cryo-electron microscopy to determine a series of the small mitoribosomal subunit (SSU) intermediates in complex with auxiliary factors, revealing a sequential assembly mechanism. The methyltransferase TFB1M binds to partially unfolded rRNA h45 that is promoted by RBFA, while the mRNA channel is blocked. This enables binding of METTL15 that promotes further rRNA maturation and a large conformational change of RBFA. The new conformation allows initiation factor mtIF3 to already occupy the subunit interface during the assembly. Finally, the mitochondria-specific ribosomal protein mS37 (ref. 1) outcompetes RBFA to complete the assembly with the SSU-mS37-mtIF3 complex2 that proceeds towards mtIF2 binding and translation initiation. Our results explain how the action of step-specific factors modulate the dynamic assembly of the SSU, and adaptation of a unique protein, mS37, links the assembly to initiation to establish the catalytic human mitoribosome.
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Affiliation(s)
- Yuzuru Itoh
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Anas Khawaja
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Max Planck Institute for Biology of Ageing-Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Ivan Laptev
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Miriam Cipullo
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Max Planck Institute for Biology of Ageing-Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Ilian Atanassov
- Proteomics Core Facility, Max-Planck-Institute for Biology of Ageing, Cologne, Germany
| | - Petr Sergiev
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, Russia
| | - Joanna Rorbach
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
- Max Planck Institute for Biology of Ageing-Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden.
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.
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23
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Zhao Y, Rai J, Xu C, He H, Li H. Artificial intelligence-assisted cryoEM structure of Bfr2-Lcp5 complex observed in the yeast small subunit processome. Commun Biol 2022; 5:523. [PMID: 35650250 PMCID: PMC9160021 DOI: 10.1038/s42003-022-03500-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic ribosome is maturated through an elaborate process that includes modification, processing and folding of pre-ribosomal RNA (pre-rRNAs) by a series of ribosome assembly intermediates. More than 70 factors participate in the dynamic assembly and disassembly of the small subunit processome (90S) inside nucleolus, leading to the early maturation of small subunit. The 5' domain of the 18S rRNA is the last to be incorporated into the stable 90S prior to the cleavage of pre-rRNA at the A1 site. This step is facilitated by the Kre33-Enp2-Bfr2-Lcp5 protein module with the participation of the DEAD-box protein Dbp4. Though structures of Kre33 and Enp2 have been modeled in previously observed 90S structures, that of Bfr2-Lcp5 complex remains unavailable. Here, we report an AlphaFold-assisted structure determination of the Bfr2-Lcp5 complex captured in a 3.99 Å - 7.24 Å cryoEM structure of 90S isolated from yeast cells depleted of Pih1, a chaperone protein of the 90S core assembly. The structure model is consistent with the protein-protein interaction results and the secondary structures of recombinant Bfr2 and Bfr2-Lcp5 complex obtained by Circular Dichroism. The Bfr2-Lcp5 complex interaction mimics that of exosome factors Rrp6-Rrp47 and acts to regulate 90S transitions.
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Affiliation(s)
- Yu Zhao
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Jay Rai
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Chong Xu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA
| | - Huan He
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA.
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA.
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24
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Liu X, Huang H, Karbstein K. Using DMS-MaPseq to Uncover the Roles of DEAD-box Proteins in Ribosome Assembly. Methods 2022; 204:249-257. [PMID: 35550176 PMCID: PMC10152975 DOI: 10.1016/j.ymeth.2022.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/27/2022] [Accepted: 05/05/2022] [Indexed: 12/20/2022] Open
Abstract
DMS (dimethylsulfate) is a time-tested chemical probe for nucleic acid secondary structure that has recently re-emerged as a powerful tool to study RNA structure and structural changes, by coupling it to high throughput sequencing techniques. This variant, termed DMS-MaPseq, allows for mapping of all RNAs in a cell at the same time. However, if an RNA adopts different structures, for example during the assembly of an RNA-protein complex, or as part of its functional cycle, then DMS-MaPseq cannot differentiate between these structures, and an ensemble average will be produced. This is especially challenging for long-lived RNAs, such as ribosomes, whose steady-state abundance far exceeds that of any assembly intermediates, rendering those inaccessible to DMS-MaPseq on total RNAs. These challenges can be overcome by purification of assembly intermediates stalled at specific assembly steps (or steps in the functional cycle), via a combination of affinity tags and mutants stalled at defined steps, and subsequent DMS probing of these intermediates. Interpretation of the differences in DMS accessibility is facilitated by additional structural information, e.g. from cryo-EM experiments, available for many functional RNAs. While this approach is generally useful for studying RNA folding or conformational changes within RNA-protein complexes, it can be particularly valuable for studying the role(s) of DEAD-box proteins, as these tend to lead to larger conformational rearrangements, often resulting from the release of an RNA-binding protein from a bound RNA. Here we provide an adaptation of the DMS-MaPseq protocol to study RNA conformational transitions during ribosome assembly, which addresses the challenges arising from the presence of many assembly intermediates, all at concentrations far below that of mature ribosomes. While this protocol was developed for the yeast S. cerevisiae, we anticipate that it should be readily transferable to other model organisms for which affinity purification has been established.
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25
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Ismail S, Flemming D, Thoms M, Gomes-Filho JV, Randau L, Beckmann R, Hurt E. Emergence of the primordial pre-60S from the 90S pre-ribosome. Cell Rep 2022; 39:110640. [PMID: 35385737 PMCID: PMC8994135 DOI: 10.1016/j.celrep.2022.110640] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 02/01/2022] [Accepted: 03/16/2022] [Indexed: 01/03/2023] Open
Abstract
Synthesis of ribosomes begins in the nucleolus with formation of the 90S pre-ribosome, during which the pre-40S and pre-60S pathways diverge by pre-rRNA cleavage. However, it remains unclear how, after this uncoupling, the earliest pre-60S subunit continues to develop. Here, we reveal a large-subunit intermediate at the beginning of its construction when still linked to the 90S, the precursor to the 40S subunit. This primordial pre-60S is characterized by the SPOUT domain methyltransferase Upa1-Upa2, large α-solenoid scaffolds, Mak5, one of several RNA helicases, and two small nucleolar RNA (snoRNAs), C/D box snR190 and H/ACA box snR37. The emerging pre-60S does not efficiently disconnect from the 90S pre-ribosome in a dominant mak5 helicase mutant, allowing a 70-nm 90S-pre-60S bipartite particle to be visualized by electron microscopy. Our study provides insight into the assembly pathway when the still-connected nascent 40S and 60S subunits are beginning to separate.
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Affiliation(s)
- Sherif Ismail
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Dirk Flemming
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Matthias Thoms
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany
| | | | - Lennart Randau
- Philipps-Universität Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Roland Beckmann
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany.
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
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26
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Huang H, Parker M, Karbstein K. The modifying enzyme Tsr3 establishes the hierarchy of Rio kinase binding in 40S ribosome assembly. RNA (NEW YORK, N.Y.) 2022; 28:568-582. [PMID: 35031584 PMCID: PMC8925970 DOI: 10.1261/rna.078994.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Ribosome assembly is an intricate process, which in eukaryotes is promoted by a large machinery comprised of over 200 assembly factors (AFs) that enable the modification, folding, and processing of the ribosomal RNA (rRNA) and the binding of the 79 ribosomal proteins. While some early assembly steps occur via parallel pathways, the process overall is highly hierarchical, which allows for the integration of maturation steps with quality control processes that ensure only fully and correctly assembled subunits are released into the translating pool. How exactly this hierarchy is established, in particular given that there are many instances of RNA substrate "handover" from one highly related AF to another, remains to be determined. Here we have investigated the role of Tsr3, which installs a universally conserved modification in the P-site of the small ribosomal subunit late in assembly. Our data demonstrate that Tsr3 separates the binding of the Rio kinases, Rio2 and Rio1, with whom it shares a binding site. By binding after Rio2 dissociation, Tsr3 prevents rebinding of Rio2, promoting forward assembly. After rRNA modification is complete, Tsr3 dissociates, thereby allowing for recruitment of Rio1 into its functional site. Inactive Tsr3 blocks Rio1 function, which can be rescued using mutants that bypass the requirement for Rio1 activity. Finally, yeast strains lacking Tsr3 randomize the binding of the two kinases, leading to the release of immature ribosomes into the translating pool. These data demonstrate a role for Tsr3 and its modification activity in establishing a hierarchy for the function of the Rio kinases.
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Affiliation(s)
- Haina Huang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
- Skaggs Graduate School of Chemical and Biological Sciences at Scripps Research, Jupiter, Florida 33458, USA
| | - Melissa Parker
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
- Skaggs Graduate School of Chemical and Biological Sciences at Scripps Research, Jupiter, Florida 33458, USA
| | - Katrin Karbstein
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
- Skaggs Graduate School of Chemical and Biological Sciences at Scripps Research, Jupiter, Florida 33458, USA
- HHMI Faculty Scholar, Chevy Chase, Maryland 20815, USA
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27
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Scaltsoyiannes V, Corre N, Waltz F, Giegé P. Types and Functions of Mitoribosome-Specific Ribosomal Proteins across Eukaryotes. Int J Mol Sci 2022; 23:ijms23073474. [PMID: 35408834 PMCID: PMC8998825 DOI: 10.3390/ijms23073474] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/17/2022] [Accepted: 03/21/2022] [Indexed: 02/04/2023] Open
Abstract
Mitochondria are key organelles that combine features inherited from their bacterial endosymbiotic ancestor with traits that arose during eukaryote evolution. These energy producing organelles have retained a genome and fully functional gene expression machineries including specific ribosomes. Recent advances in cryo-electron microscopy have enabled the characterization of a fast-growing number of the low abundant membrane-bound mitochondrial ribosomes. Surprisingly, mitoribosomes were found to be extremely diverse both in terms of structure and composition. Still, all of them drastically increased their number of ribosomal proteins. Interestingly, among the more than 130 novel ribosomal proteins identified to date in mitochondria, most of them are composed of a-helices. Many of them belong to the nuclear encoded super family of helical repeat proteins. Here we review the diversity of functions and the mode of action held by the novel mitoribosome proteins and discuss why these proteins that share similar helical folds were independently recruited by mitoribosomes during evolution in independent eukaryote clades.
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Affiliation(s)
- Vassilis Scaltsoyiannes
- CNRS, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, 67084 Strasbourg, France; (V.S.); (N.C.)
| | - Nicolas Corre
- CNRS, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, 67084 Strasbourg, France; (V.S.); (N.C.)
| | - Florent Waltz
- CNRS, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, 67084 Strasbourg, France; (V.S.); (N.C.)
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Munich, Germany
- Correspondence: (F.W.); (P.G.); Tel.: +33-3-6715-5363 (P.G.); Fax: +33-3-8861-4442 (P.G.)
| | - Philippe Giegé
- CNRS, Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, 67084 Strasbourg, France; (V.S.); (N.C.)
- Correspondence: (F.W.); (P.G.); Tel.: +33-3-6715-5363 (P.G.); Fax: +33-3-8861-4442 (P.G.)
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28
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Black JJ, Johnson AW. Release of the ribosome biogenesis factor Bud23 from small subunit precursors in yeast. RNA (NEW YORK, N.Y.) 2022; 28:371-389. [PMID: 34934010 PMCID: PMC8848936 DOI: 10.1261/rna.079025.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
The two subunits of the eukaryotic ribosome are produced through quasi-independent pathways involving the hierarchical actions of numerous trans-acting biogenesis factors and the incorporation of ribosomal proteins. The factors work together to shape the nascent subunits through a series of intermediate states into their functional architectures. One of the earliest intermediates of the small subunit (SSU or 40S) is the SSU processome which is subsequently transformed into the pre-40S intermediate. This transformation is, in part, facilitated by the binding of the methyltransferase Bud23. How Bud23 is released from the resultant pre-40S is not known. The ribosomal proteins Rps0, Rps2, and Rps21, termed the Rps0-cluster proteins, and several biogenesis factors bind the pre-40S around the time that Bud23 is released, suggesting that one or more of these factors could induce Bud23 release. Here, we systematically examined the requirement of these factors for the release of Bud23 from pre-40S particles. We found that the Rps0-cluster proteins are needed but not sufficient for Bud23 release. The atypical kinase/ATPase Rio2 shares a binding site with Bud23 and is thought to be recruited to pre-40S after the Rps0-cluster proteins. Depletion of Rio2 prevented the release of Bud23 from the pre-40S. More importantly, the addition of recombinant Rio2 to pre-40S particles affinity-purified from Rio2-depleted cells was sufficient for Bud23 release in vitro. The ability of Rio2 to displace Bud23 was independent of nucleotide hydrolysis. We propose a novel role for Rio2 in which its binding to the pre-40S actively displaces Bud23 from the pre-40S.
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Affiliation(s)
- Joshua J Black
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Arlen W Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA
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29
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Vanden Broeck A, Klinge S. An emerging mechanism for the maturation of the Small Subunit Processome. Curr Opin Struct Biol 2022; 73:102331. [PMID: 35176592 DOI: 10.1016/j.sbi.2022.102331] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/14/2021] [Accepted: 01/10/2022] [Indexed: 12/15/2022]
Abstract
The biogenesis of the eukaryotic ribosome is a tightly regulated and energetically demanding process involving more than 200 ribosome assembly factors. These factors work in concert to ensure accurate assembly and maturation of both ribosomal subunits. Cryo-electron microscopy (cryo-EM) structures of numerous eukaryotic ribosome assembly intermediates have provided a wealth of structural insights highlighting the molecular interplay of a cast of assembly factors. In this review, we focus on recently determined structures of maturing small subunit (SSU) processomes, giant precursors of the small ribosomal subunit. Based on these structures and complementary biochemical and genetic studies, we discuss an emerging mechanism involving exosome-mediated SSU processome maturation and disassembly.
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Affiliation(s)
- Arnaud Vanden Broeck
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA. https://twitter.com/AVBroeck
| | - Sebastian Klinge
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA.
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30
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Dielforder T, Braun CM, Hölzgen F, Li S, Thiele M, Huber M, Ohmayer U, Perez-Fernandez J. Structural Probing with MNase Tethered to Ribosome Assembly Factors Resolves Flexible RNA Regions within the Nascent Pre-Ribosomal RNA. Noncoding RNA 2022; 8:ncrna8010001. [PMID: 35076539 PMCID: PMC8788456 DOI: 10.3390/ncrna8010001] [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: 12/23/2021] [Revised: 01/02/2022] [Accepted: 01/05/2022] [Indexed: 12/04/2022] Open
Abstract
The synthesis of ribosomes involves the correct folding of the pre-ribosomal RNA within pre-ribosomal particles. The first ribosomal precursor or small subunit processome assembles stepwise on the nascent transcript of the 35S gene. At the earlier stages, the pre-ribosomal particles undergo structural and compositional changes, resulting in heterogeneous populations of particles with highly flexible regions. Structural probing methods are suitable for resolving these structures and providing evidence about the architecture of ribonucleoprotein complexes. Our approach used MNase tethered to the assembly factors Nan1/Utp17, Utp10, Utp12, and Utp13, which among other factors, initiate the formation of the small subunit processome. Our results provide dynamic information about the folding of the pre-ribosomes by elucidating the relative organization of the 5′ETS and ITS1 regions within the 35S and U3 snoRNA around the C-terminal domains of Nan1/Utp17, Utp10, Utp12, and Utp13.
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31
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Karbstein K. Attacking a DEAD problem: The role of DEAD-box ATPases in ribosome assembly and beyond. Methods Enzymol 2022; 673:19-38. [PMID: 35965007 PMCID: PMC10154911 DOI: 10.1016/bs.mie.2022.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DEAD-box proteins are a subfamily of ATPases with similarity to RecA-type helicases that are involved in all aspects of RNA Biology. Despite their potential to regulate these processes via their RNA-dependent ATPase activity, their roles remain poorly characterized. Here I describe a roadmap to study these proteins in the context of ribosome assembly, the process that utilizes more than half of all DEAD-box proteins encoded in the yeast genome.
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Affiliation(s)
- Katrin Karbstein
- Department of Integrative Structural and Computational Biology, Scripps Florida, Jupiter, FL, United States; HHMI Faculty Scholar, Chevy Chase, MD, United States; The Skaggs Graduate School of Chemical and Biological Sciences, Scripps Florida, Jupiter, FL, United States.
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32
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Moraleva AA, Deryabin AS, Rubtsov YP, Rubtsova MP, Dontsova OA. Eukaryotic Ribosome Biogenesis: The 40S Subunit. Acta Naturae 2022; 14:14-30. [PMID: 35441050 PMCID: PMC9013438 DOI: 10.32607/actanaturae.11540] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 02/02/2022] [Indexed: 11/29/2022] Open
Abstract
The formation of eukaryotic ribosomes is a sequential process of ribosomal
precursors maturation in the nucleolus, nucleoplasm, and cytoplasm. Hundreds of
ribosomal biogenesis factors ensure the accurate processing and formation of
the ribosomal RNAs’ tertiary structure, and they interact with ribosomal
proteins. Most of what we know about the ribosome assembly has been derived
from yeast cell studies, and the mechanisms of ribosome biogenesis in
eukaryotes are considered quite conservative. Although the main stages of
ribosome biogenesis are similar across different groups of eukaryotes, this
process in humans is much more complicated owing to the larger size of the
ribosomes and pre-ribosomes and the emergence of regulatory pathways that
affect their assembly and function. Many of the factors involved in the
biogenesis of human ribosomes have been identified using genome-wide screening
based on RNA interference. This review addresses the key aspects of yeast and
human ribosome biogenesis, using the 40S subunit as an example. The mechanisms
underlying these differences are still not well understood, because, unlike
yeast, there are no effective methods for characterizing pre-ribosomal
complexes in humans. Understanding the mechanisms of human ribosome assembly
would have an incidence on a growing number of genetic diseases
(ribosomopathies) caused by mutations in the genes encoding ribosomal proteins
and ribosome biogenesis factors. In addition, there is evidence that ribosome
assembly is regulated by oncogenic signaling pathways, and that defects in the
ribosome biogenesis are linked to the activation of tumor suppressors.
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Affiliation(s)
- A. A. Moraleva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - A. S. Deryabin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - Yu. P. Rubtsov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - M. P. Rubtsova
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991 Russia
| | - O. A. Dontsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991 Russia
- Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
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33
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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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34
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In vitro characterization of Dhr1 from Saccharomyces cerevisiae. Methods Enzymol 2022; 673:77-101. [DOI: 10.1016/bs.mie.2022.03.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Rössler I, Weigl S, Fernández-Fernández J, Martín-Villanueva S, Strauss D, Hurt E, de la Cruz J, Pertschy B. The C-terminal tail of ribosomal protein Rps15 is engaged in cytoplasmic pre-40S maturation. RNA Biol 2021; 19:560-574. [PMID: 35438042 PMCID: PMC9037480 DOI: 10.1080/15476286.2022.2064073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 04/04/2022] [Indexed: 11/22/2022] Open
Abstract
The small ribosomal subunit protein Rps15/uS19 is involved in early nucleolar ribosome biogenesis and subsequent nuclear export of pre-40S particles to the cytoplasm. In addition, the C-terminal tail of Rps15 was suggested to play a role in mature ribosomes, namely during translation elongation. Here, we show that Rps15 not only functions in nucleolar ribosome assembly but also in cytoplasmic pre-40S maturation, which is indicated by a strong genetic interaction between Rps15 and the 40S assembly factor Ltv1. Specifically, mutations either in the globular or C-terminal domain of Rps15 when combined with the non-essential ltv1 null allele are lethal or display a strong growth defect. However, not only rps15 ltv1 double mutants but also single rps15 C-terminal deletion mutants exhibit an accumulation of the 20S pre-rRNA in the cytoplasm, indicative of a cytoplasmic pre-40S maturation defect. Since in pre-40S particles, the C-terminal tail of Rps15 is positioned between assembly factors Rio2 and Tsr1, we further tested whether Tsr1 is genetically linked to Rps15, which indeed could be demonstrated. Thus, the integrity of the Rps15 C-terminal tail plays an important role during late pre-40S maturation, perhaps in a quality control step to ensure that only 40S ribosomal subunits with functional Rps15 C-terminal tail can efficiently enter translation. As mutations in the C-terminal tail of human RPS15 have been observed in connection with chronic lymphocytic leukaemia, it is possible that apart from defects in translation, an impaired late pre-40S maturation step in the cytoplasm could also be a reason for this disease.
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Affiliation(s)
- Ingrid Rössler
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Sarah Weigl
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - José Fernández-Fernández
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Sara Martín-Villanueva
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - Daniela Strauss
- Biochemistry Center BZH, Heidelberg University, Heidelberg, Germany
| | - Ed Hurt
- Biochemistry Center BZH, Heidelberg University, Heidelberg, Germany
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Brigitte Pertschy
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
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36
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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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37
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Nieto B, Gaspar SG, Sapio RT, Clavaín L, Bustelo XR, Pestov DG, Dosil M. Efficient fractionation and analysis of ribosome assembly intermediates in human cells. RNA Biol 2021; 18:182-197. [PMID: 34530680 PMCID: PMC8682975 DOI: 10.1080/15476286.2021.1965754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Biochemical studies of the human ribosome synthesis pathway have been hindered by technical difficulties in obtaining intact preribosomal complexes from internal regions of the nucleolus. Here we provide a detailed description of an extraction method that enables efficient detection, isolation, and characterization of nucleolar preribosomes containing large pre-rRNA species. The three-step Preribosome Sequential Extraction (PSE) protocol preserves the integrity of early preribosomal complexes and yields preparations amenable to biochemical analyses from low amounts of starting material. We validate this procedure through the detection of specific trans-acting factors and pre-rRNAs in the extracted preribosomes using affinity matrix pull-downs and sedimentation assays. In addition, we describe the application of the PSE method for monitoring cellular levels of ribosome-free 5S RNP complexes as an indicator of ribosome biogenesis stress. Our optimized experimental procedures will facilitate studies of human ribosome biogenesis in normal, mutant and stressed-cell scenarios, including the characterization of candidate ribosome biogenesis factors, preribosome interactors under specific physiological conditions or effects of drugs on ribosome maturation.
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Affiliation(s)
- Blanca Nieto
- Centro de Investigación del Cáncer, Salamanca, Spain.,Instituto de Biología Molecular y Celular del Cáncer, CSIC-University of Salamanca, Salamanca, Spain
| | - Sonia G Gaspar
- Centro de Investigación del Cáncer, Salamanca, Spain.,Instituto de Biología Molecular y Celular del Cáncer, CSIC-University of Salamanca, Salamanca, Spain
| | - Russell T Sapio
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, USA.,Graduate School of Biomedical Sciences, Rowan University School of Osteopathic Medicine, Stratford, USA
| | - Laura Clavaín
- Centro de Investigación del Cáncer, Salamanca, Spain.,Instituto de Biología Molecular y Celular del Cáncer, CSIC-University of Salamanca, Salamanca, Spain.,Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Centro de Investigación del Cáncer, Salamanca, Spain
| | - Xosé R Bustelo
- Centro de Investigación del Cáncer, Salamanca, Spain.,Instituto de Biología Molecular y Celular del Cáncer, CSIC-University of Salamanca, Salamanca, Spain.,Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Centro de Investigación del Cáncer, Salamanca, Spain
| | - Dimitri G Pestov
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, USA
| | - Mercedes Dosil
- Centro de Investigación del Cáncer, Salamanca, Spain.,Instituto de Biología Molecular y Celular del Cáncer, CSIC-University of Salamanca, Salamanca, Spain.,Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Centro de Investigación del Cáncer, Salamanca, Spain.,Departamento de Bioquímica y Biología Molecular, University of Salamanca, Salamanca, Spain
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38
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Singh S, Vanden Broeck A, Miller L, Chaker-Margot M, Klinge S. Nucleolar maturation of the human small subunit processome. Science 2021; 373:eabj5338. [PMID: 34516797 DOI: 10.1126/science.abj5338] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Sameer Singh
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Arnaud Vanden Broeck
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Linamarie Miller
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA.,Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, New York, NY 10065, USA
| | - Malik Chaker-Margot
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA.,Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, New York, NY 10065, USA
| | - Sebastian Klinge
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA
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39
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Assembly factors chaperone ribosomal RNA folding by isolating helical junctions that are prone to misfolding. Proc Natl Acad Sci U S A 2021; 118:2101164118. [PMID: 34135123 DOI: 10.1073/pnas.2101164118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
While RNAs are known to misfold, the underlying molecular causes have been mainly studied in fragments of biologically relevant larger RNAs. As these small RNAs are dominated by secondary structures, misfolding of these secondary structures remains the most-explored cause for global RNA misfolding. Conversely, how RNA chaperones function in a biological context to promote native folding beyond duplex annealing remains unknown. Here, in a combination of dimethylsulfate mutational profiling with sequencing (DMS-MaPseq), structural analyses, biochemical experiments, and yeast genetics, we show that three-helix junctions are prone to misfolding during assembly of the small ribosomal subunit in vivo. We identify ubiquitous roles for ribosome assembly factors in chaperoning their folding by preventing the formation of premature tertiary interactions, which otherwise kinetically trap misfolded junctions, thereby blocking further progress in the assembly cascade. While these protein chaperones act indirectly by binding the interaction partners of junctions, our analyses also suggest direct roles for small nucleolar RNAs (snoRNAs) in binding and chaperoning helical junctions during transcription. While these assembly factors do not utilize energy to ameliorate misfolding, our data demonstrate how their dissociation renders reversible folding steps irreversible, thereby driving native folding and assembly and setting up a timer that dictates the propensity of misfolded intermediates to escape quality control. Finally, the data demonstrate that RNA chaperones act locally on individual tertiary interactions, in contrast to protein chaperones, which globally unfold misfolded proteins.
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40
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Tartakoff AM, Chen L, Raghavachari S, Gitiforooz D, Dhinakaran A, Ni CL, Pasadyn C, Mahabeleshwar GH, Pasadyn V, Woolford JL. The nucleolus as a polarized coaxial cable in which the rDNA axis is surrounded by dynamic subunit-specific phases. Curr Biol 2021; 31:2507-2519.e4. [PMID: 33862007 PMCID: PMC8222187 DOI: 10.1016/j.cub.2021.03.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 01/18/2021] [Accepted: 03/11/2021] [Indexed: 12/24/2022]
Abstract
In ribosomal DNA (rDNA) repeats, sequences encoding small-subunit (SSU) rRNA precede those encoding large-subunit (LSU) rRNAs. Processing the composite transcript and subunit assembly requires >100 subunit-specific nucleolar assembly factors (AFs). To investigate the functional organization of the nucleolus, we localized AFs in S. cerevisiae in which the rDNA axis was "linearized" to reduce its dimensionality, thereby revealing its coaxial organization. In this situation, rRNA synthesis and processing continue. The axis is embedded in an inner layer/phase of SSU AFs that is surrounded by an outer layer/phase of LSU AFs. When subunit production is inhibited, subsets of AFs differentially relocate between the inner and outer layers, as expected if there is a cycle of repeated relocation whereby "latent" AFs become "operative" when recruited to nascent subunits. Recognition of AF cycling and localization of segments of rRNA make it possible to infer the existence of assembly intermediates that span between the inner and outer layers and to chart the cotranscriptional assembly of each subunit. AF cycling also can explain how having more than one protein phase in the nucleolus makes possible "vectorial 2-phase partitioning" as a driving force for relocation of nascent rRNPs. Because nucleoplasmic AFs are also present in the outer layer, we propose that critical surface remodeling occurs at this site, thereby partitioning subunit precursors into the nucleoplasm for post-transcriptional maturation. Comparison to observations on higher eukaryotes shows that the coaxial paradigm is likely to be applicable for the many other organisms that have rDNA repeats.
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Affiliation(s)
- Alan M Tartakoff
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA.
| | - Lan Chen
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - Shashank Raghavachari
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - Daria Gitiforooz
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - Akshyasri Dhinakaran
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - Chun-Lun Ni
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | | | - Ganapati H Mahabeleshwar
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - Vanessa Pasadyn
- Department of Pathology and Cell Biology Program, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
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41
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PNO1 regulates autophagy and apoptosis of hepatocellular carcinoma via the MAPK signaling pathway. Cell Death Dis 2021; 12:552. [PMID: 34050137 PMCID: PMC8163843 DOI: 10.1038/s41419-021-03837-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 12/13/2022]
Abstract
Some studies have reported that activated ribosomes are positively associated with malignant tumors, especially in hepatocellular carcinoma (HCC). The RNA-binding protein PNO1 is a critical ribosome rarely reported in human tumors. This study aimed to explore the molecular mechanisms of PNO1 in HCC. Using 150 formalin-fixed and paraffin-embedded samples and 8 fresh samples, we found high PNO1 expression in HCC tumor tissues through Western blotting and RT-PCR. Moreover, the higher PNO1 expression was associated with poor HCC prognosis patients. In vitro and in vivo experiments indicated that PNO1 overexpression promoted the proliferation and depressed the apoptosis of HCC cells. High PNO1 expression also increased the autophagy of HCC cells. The molecular mechanisms underlying PNO1 were examined by RNA-seq analysis and a series of functional experiments. Results showed that PNO1 promoted HCC progression through the MAPK signaling pathway. Therefore, PNO1 was overexpressed in HCC, promoted autophagy, and inhibited the apoptosis of HCC cells through the MAPK signaling pathway.
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42
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YbeY, éminence grise of ribosome biogenesis. Biochem Soc Trans 2021; 49:727-745. [PMID: 33929506 DOI: 10.1042/bst20200669] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/30/2022]
Abstract
YbeY is an ultraconserved small protein belonging to the unique heritage shared by most existing bacteria and eukaryotic organelles of bacterial origin, mitochondria and chloroplasts. Studied in more than a dozen of evolutionarily distant species, YbeY is invariably critical for cellular physiology. However, the exact mechanisms by which it exerts such penetrating influence are not completely understood. In this review, we attempt a transversal analysis of the current knowledge about YbeY, based on genetic, structural, and biochemical data from a wide variety of models. We propose that YbeY, in association with the ribosomal protein uS11 and the assembly GTPase Era, plays a critical role in the biogenesis of the small ribosomal subunit, and more specifically its platform region, in diverse genetic systems of bacterial type.
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43
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Black JJ, Johnson AW. Genetics animates structure: leveraging genetic interactions to study the dynamics of ribosome biogenesis. Curr Genet 2021; 67:729-738. [PMID: 33844044 DOI: 10.1007/s00294-021-01187-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 11/26/2022]
Abstract
The assembly of eukaryotic ribosomes follows an assembly line-like pathway in which numerous trans-acting biogenesis factors act on discrete pre-ribosomal intermediates to progressively shape the nascent subunits into their final functional architecture. Recent advances in cryo-electron microscopy have led to high-resolution structures of many pre-ribosomal intermediates; however, these static snapshots do not capture the dynamic transitions between these intermediates. To this end, molecular genetics can be leveraged to reveal how the biogenesis factors drive these dynamic transitions. Here, we briefly review how we recently used the deletion of BUD23 (bud23∆) to understand its role in the assembly of the ribosomal small subunit. The strong growth defect of bud23∆ mutants places a selective pressure on yeast cells for the occurrence of extragenic suppressors that define a network of functional interactions among biogenesis factors. Mapping these suppressing mutations to recently published structures of pre-ribosomal complexes allowed us to contextualize these suppressing mutations and derive a detailed model in which Bud23 promotes a critical transition event to facilitate folding of the central pseudoknot of the small subunit. This mini-review highlights how genetics can be used to understand the dynamics of complex structures, such as the maturing ribosome.
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Affiliation(s)
- Joshua J Black
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA
| | - Arlen W Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA.
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44
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Gerovac M, Vogel J, Smirnov A. The World of Stable Ribonucleoproteins and Its Mapping With Grad-Seq and Related Approaches. Front Mol Biosci 2021; 8:661448. [PMID: 33898526 PMCID: PMC8058203 DOI: 10.3389/fmolb.2021.661448] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/04/2021] [Indexed: 12/13/2022] Open
Abstract
Macromolecular complexes of proteins and RNAs are essential building blocks of cells. These stable supramolecular particles can be viewed as minimal biochemical units whose structural organization, i.e., the way the RNA and the protein interact with each other, is directly linked to their biological function. Whether those are dynamic regulatory ribonucleoproteins (RNPs) or integrated molecular machines involved in gene expression, the comprehensive knowledge of these units is critical to our understanding of key molecular mechanisms and cell physiology phenomena. Such is the goal of diverse complexomic approaches and in particular of the recently developed gradient profiling by sequencing (Grad-seq). By separating cellular protein and RNA complexes on a density gradient and quantifying their distributions genome-wide by mass spectrometry and deep sequencing, Grad-seq charts global landscapes of native macromolecular assemblies. In this review, we propose a function-based ontology of stable RNPs and discuss how Grad-seq and related approaches transformed our perspective of bacterial and eukaryotic ribonucleoproteins by guiding the discovery of new RNA-binding proteins and unusual classes of noncoding RNAs. We highlight some methodological aspects and developments that permit to further boost the power of this technique and to look for exciting new biology in understudied and challenging biological models.
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Affiliation(s)
- Milan Gerovac
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
| | - Jörg Vogel
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Alexandre Smirnov
- UMR 7156—Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, CNRS, Strasbourg, France
- University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
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45
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An RNA-centric historical narrative around the Protein Data Bank. J Biol Chem 2021; 296:100555. [PMID: 33744291 PMCID: PMC8080527 DOI: 10.1016/j.jbc.2021.100555] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/17/2021] [Accepted: 03/16/2021] [Indexed: 01/06/2023] Open
Abstract
Some of the amazing contributions brought to the scientific community by the Protein Data Bank (PDB) are described. The focus is on nucleic acid structures with a bias toward RNA. The evolution and key roles in science of the PDB and other structural databases for nucleic acids illustrate how small initial ideas can become huge and indispensable resources with the unflinching willingness of scientists to cooperate globally. The progress in the understanding of the molecular interactions driving RNA architectures followed the rapid increase in RNA structures in the PDB. That increase was consecutive to improvements in chemical synthesis and purification of RNA molecules, as well as in biophysical methods for structure determination and computer technology. The RNA modeling efforts from the early beginnings are also described together with their links to the state of structural knowledge and technological development. Structures of RNA and of its assemblies are physical objects, which, together with genomic data, allow us to integrate present-day biological functions and the historical evolution in all living species on earth.
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46
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Knüppel R, Trahan C, Kern M, Wagner A, Grünberger F, Hausner W, Quax TEF, Albers SV, Oeffinger M, Ferreira-Cerca S. Insights into synthesis and function of KsgA/Dim1-dependent rRNA modifications in archaea. Nucleic Acids Res 2021; 49:1662-1687. [PMID: 33434266 PMCID: PMC7897474 DOI: 10.1093/nar/gkaa1268] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/01/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022] Open
Abstract
Ribosomes are intricate molecular machines ensuring proper protein synthesis in every cell. Ribosome biogenesis is a complex process which has been intensively analyzed in bacteria and eukaryotes. In contrast, our understanding of the in vivo archaeal ribosome biogenesis pathway remains less characterized. Here, we have analyzed the in vivo role of the almost universally conserved ribosomal RNA dimethyltransferase KsgA/Dim1 homolog in archaea. Our study reveals that KsgA/Dim1-dependent 16S rRNA dimethylation is dispensable for the cellular growth of phylogenetically distant archaea. However, proteomics and functional analyses suggest that archaeal KsgA/Dim1 and its rRNA modification activity (i) influence the expression of a subset of proteins and (ii) contribute to archaeal cellular fitness and adaptation. In addition, our study reveals an unexpected KsgA/Dim1-dependent variability of rRNA modifications within the archaeal phylum. Combining structure-based functional studies across evolutionary divergent organisms, we provide evidence on how rRNA structure sequence variability (re-)shapes the KsgA/Dim1-dependent rRNA modification status. Finally, our results suggest an uncoupling between the KsgA/Dim1-dependent rRNA modification completion and its release from the nascent small ribosomal subunit. Collectively, our study provides additional understandings into principles of molecular functional adaptation, and further evolutionary and mechanistic insights into an almost universally conserved step of ribosome synthesis.
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Affiliation(s)
- Robert Knüppel
- Regensburg Center for Biochemistry, Biochemistry III – Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Christian Trahan
- Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec H2W 1R7, Canada
- Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
- Département de Biochimie, Faculté de Médecine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Michael Kern
- Regensburg Center for Biochemistry, Biochemistry III – Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Alexander Wagner
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, Microbiology, University of Freiburg, Freiburg, Germany
| | - Felix Grünberger
- Chair of Microbiology – Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Winfried Hausner
- Chair of Microbiology – Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Tessa E F Quax
- Archaeal Virus-Host Interactions, Institute of Biology II, Faculty of Biology, Microbiology, University of Freiburg, Freiburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, Faculty of Biology, Microbiology, University of Freiburg, Freiburg, Germany
| | - Marlene Oeffinger
- Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec H2W 1R7, Canada
- Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
- Département de Biochimie, Faculté de Médecine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Sébastien Ferreira-Cerca
- Regensburg Center for Biochemistry, Biochemistry III – Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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47
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Hang R, Wang Z, Yang C, Luo L, Mo B, Chen X, Sun J, Liu C, Cao X. Protein arginine methyltransferase 3 fine-tunes the assembly/disassembly of pre-ribosomes to repress nucleolar stress by interacting with RPS2B in arabidopsis. MOLECULAR PLANT 2021; 14:223-236. [PMID: 33069875 DOI: 10.1016/j.molp.2020.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 08/17/2020] [Accepted: 10/13/2020] [Indexed: 06/11/2023]
Abstract
Ribosome biogenesis, which takes place mainly in the nucleolus, involves coordinated expression of pre-ribosomal RNAs (pre-rRNAs) and ribosomal proteins, pre-rRNA processing, and subunit assembly with the aid of numerous assembly factors. Our previous study showed that the Arabidopsis thaliana protein arginine methyltransferase AtPRMT3 regulates pre-rRNA processing; however, the underlying molecular mechanism remains unknown. Here, we report that AtPRMT3 interacts with Ribosomal Protein S2 (RPS2), facilitating processing of the 90S/Small Subunit (SSU) processome and repressing nucleolar stress. We isolated an intragenic suppressor of atprmt3-2, which rescues the developmental defects of atprmt3-2 while produces a putative truncated AtPRMT3 protein bearing the entire N-terminus but lacking an intact enzymatic activity domain We further identified RPS2 as an interacting partner of AtPRMT3, and found that loss-of-function rps2a2b mutants were phenotypically reminiscent of atprmt3, showing pleiotropic developmental defects and aberrant pre-rRNA processing. RPS2B binds directly to pre-rRNAs in the nucleus, and such binding is enhanced in atprmt3-2. Consistently, multiple components of the 90S/SSU processome were more enriched by RPS2B in atprmt3-2, which accounts for early pre-rRNA processing defects and results in nucleolar stress. Collectively, our study uncovered a novel mechanism by which AtPRMT3 cooperates with RPS2B to facilitate the dynamic assembly/disassembly of the 90S/SSU processome during ribosome biogenesis and repress nucleolar stress.
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Affiliation(s)
- Runlai Hang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Zhen Wang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Chao Yang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China
| | - Lilan Luo
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Beixin Mo
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Xuemei Chen
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Jing Sun
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Chunyan Liu
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Xiaofeng Cao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100039, China; CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Beijing 100101, China.
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48
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Bohnsack KE, Ficner R, Bohnsack MT, Jonas S. Regulation of DEAH-box RNA helicases by G-patch proteins. Biol Chem 2021; 402:561-579. [PMID: 33857358 DOI: 10.1515/hsz-2020-0338] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 12/09/2020] [Indexed: 12/22/2022]
Abstract
RNA helicases of the DEAH/RHA family form a large and conserved class of enzymes that remodel RNA protein complexes (RNPs) by translocating along the RNA. Driven by ATP hydrolysis, they exert force to dissociate hybridized RNAs, dislocate bound proteins or unwind secondary structure elements in RNAs. The sub-cellular localization of DEAH-helicases and their concomitant association with different pathways in RNA metabolism, such as pre-mRNA splicing or ribosome biogenesis, can be guided by cofactor proteins that specifically recruit and simultaneously activate them. Here we review the mode of action of a large class of DEAH-specific adaptor proteins of the G-patch family. Defined only by their eponymous short glycine-rich motif, which is sufficient for helicase binding and stimulation, this family encompasses an immensely varied array of domain compositions and is linked to an equally diverse set of functions. G-patch proteins are conserved throughout eukaryotes and are even encoded within retroviruses. They are involved in mRNA, rRNA and snoRNA maturation, telomere maintenance and the innate immune response. Only recently was the structural and mechanistic basis for their helicase enhancing activity determined. We summarize the molecular and functional details of G-patch-mediated helicase regulation in their associated pathways and their involvement in human diseases.
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Affiliation(s)
- Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany.,Göttingen Centre for Molecular Biosciences, Georg-August University, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany.,Göttingen Centre for Molecular Biosciences, Georg-August University, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Stefanie Jonas
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
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49
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Lau B, Cheng J, Flemming D, La Venuta G, Berninghausen O, Beckmann R, Hurt E. Structure of the Maturing 90S Pre-ribosome in Association with the RNA Exosome. Mol Cell 2020; 81:293-303.e4. [PMID: 33326748 DOI: 10.1016/j.molcel.2020.11.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/01/2020] [Accepted: 11/04/2020] [Indexed: 12/12/2022]
Abstract
Ribosome assembly is catalyzed by numerous trans-acting factors and coupled with irreversible pre-rRNA processing, driving the pathway toward mature ribosomal subunits. One decisive step early in this progression is removal of the 5' external transcribed spacer (5'-ETS), an RNA extension at the 18S rRNA that is integrated into the huge 90S pre-ribosome structure. Upon endo-nucleolytic cleavage at an internal site, A1, the 5'-ETS is separated from the 18S rRNA and degraded. Here we present biochemical and cryo-electron microscopy analyses that depict the RNA exosome, a major 3'-5' exoribonuclease complex, in a super-complex with the 90S pre-ribosome. The exosome is docked to the 90S through its co-factor Mtr4 helicase, a processive RNA duplex-dismantling helicase, which strategically positions the exosome at the base of 5'-ETS helices H9-H9', which are dislodged in our 90S-exosome structures. These findings suggest a direct role of the exosome in structural remodeling of the 90S pre-ribosome to drive eukaryotic ribosome synthesis.
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Affiliation(s)
- Benjamin Lau
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Jingdong Cheng
- Gene Center, Department of Biochemistry and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany
| | - Dirk Flemming
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Giuseppe La Venuta
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Otto Berninghausen
- Gene Center, Department of Biochemistry and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany
| | - Roland Beckmann
- Gene Center, Department of Biochemistry and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany.
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
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50
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Bud23 promotes the final disassembly of the small subunit Processome in Saccharomyces cerevisiae. PLoS Genet 2020; 16:e1009215. [PMID: 33306676 PMCID: PMC7758049 DOI: 10.1371/journal.pgen.1009215] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 12/23/2020] [Accepted: 10/21/2020] [Indexed: 01/18/2023] Open
Abstract
The first metastable assembly intermediate of the eukaryotic ribosomal small subunit (SSU) is the SSU Processome, a large complex of RNA and protein factors that is thought to represent an early checkpoint in the assembly pathway. Transition of the SSU Processome towards continued maturation requires the removal of the U3 snoRNA and biogenesis factors as well as ribosomal RNA processing. While the factors that drive these events are largely known, how they do so is not. The methyltransferase Bud23 has a role during this transition, but its function, beyond the nonessential methylation of ribosomal RNA, is not characterized. Here, we have carried out a comprehensive genetic screen to understand Bud23 function. We identified 67 unique extragenic bud23Δ-suppressing mutations that mapped to genes encoding the SSU Processome factors DHR1, IMP4, UTP2 (NOP14), BMS1 and the SSU protein RPS28A. These factors form a physical interaction network that links the binding site of Bud23 to the U3 snoRNA and many of the amino acid substitutions weaken protein-protein and protein-RNA interactions. Importantly, this network links Bud23 to the essential GTPase Bms1, which acts late in the disassembly pathway, and the RNA helicase Dhr1, which catalyzes U3 snoRNA removal. Moreover, particles isolated from cells lacking Bud23 accumulated late SSU Processome factors and ribosomal RNA processing defects. We propose a model in which Bud23 dissociates factors surrounding its binding site to promote SSU Processome progression. Ribosomes are the molecular machines that synthesize proteins and are composed of a large and a small subunit which carry out the essential functions of polypeptide synthesis and mRNA decoding, respectively. Ribosome production is tightly linked to cellular growth as cells must produce enough ribosomes to meet their protein needs. However, ribosome assembly is a metabolically expensive pathway that must be balanced with other cellular energy needs and regulated accordingly. In eukaryotes, the small subunit (SSU) Processome is a metastable intermediate that ultimately progresses towards a mature SSU through the release of biogenesis factors. The decision to progress the SSU Processome is thought to be an early checkpoint in the SSU assembly pathway, but insight into the mechanisms of progression is needed. Previous studies suggest that Bud23 plays an uncharacterized role during SSU Processome progression. Here, we used a genetic approach to understand its function and found that Bud23 is connected to a network of SSU Processome factors that stabilize the particle. Interestingly, two of these factors are enzymes that are needed for progression. We conclude that Bud23 promotes the release of factors surrounding its binding site to induce structural rearrangements during the progression of the SSU Processome.
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