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Espinar-Marchena FJ, Babiano R, Cruz J. Placeholder factors in ribosome biogenesis: please, pave my way. MICROBIAL CELL 2017; 4:144-168. [PMID: 28685141 PMCID: PMC5425277 DOI: 10.15698/mic2017.05.572] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The synthesis of cytoplasmic eukaryotic ribosomes is an extraordinarily energy-demanding cellular activity that occurs progressively from the nucleolus to the cytoplasm. In the nucleolus, precursor rRNAs associate with a myriad of trans-acting factors and some ribosomal proteins to form pre-ribosomal particles. These factors include snoRNPs, nucleases, ATPases, GTPases, RNA helicases, and a vast list of proteins with no predicted enzymatic activity. Their coordinate activity orchestrates in a spatiotemporal manner the modification and processing of precursor rRNAs, the rearrangement reactions required for the formation of productive RNA folding intermediates, the ordered assembly of the ribosomal proteins, and the export of pre-ribosomal particles to the cytoplasm; thus, providing speed, directionality and accuracy to the overall process of formation of translation-competent ribosomes. Here, we review a particular class of trans-acting factors known as "placeholders". Placeholder factors temporarily bind selected ribosomal sites until these have achieved a structural context that is appropriate for exchanging the placeholder with another site-specific binding factor. By this strategy, placeholders sterically prevent premature recruitment of subsequently binding factors, premature formation of structures, avoid possible folding traps, and act as molecular clocks that supervise the correct progression of pre-ribosomal particles into functional ribosomal subunits. We summarize the current understanding of those factors that delay the assembly of distinct ribosomal proteins or subsequently bind key sites in pre-ribosomal particles. We also discuss recurrent examples of RNA-protein and protein-protein mimicry between rRNAs and/or factors, which have clear functional implications for the ribosome biogenesis pathway.
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Affiliation(s)
- Francisco J Espinar-Marchena
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| | - Reyes Babiano
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain.,Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| | - Jesús Cruz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
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52
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Pertschy B. When a ribosomal protein grows up - the ribosome assembly path of Rps3. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:140-143. [PMID: 28685140 PMCID: PMC5425276 DOI: 10.15698/mic2017.05.571] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 11/29/2022]
Abstract
The biogenesis of ribosomes is a central process in all dividing cells. Eukaryotic ribosomes are composed of a large 60S and a small 40S subunit, each comprising a complex assembly of ribosomal RNA (rRNA) and ribosomal proteins (r-proteins). The synthesis of these constituents is spatially separated, with r-proteins being produced by translation in the cytoplasm, while rRNA is generated by transcription in the nucleus. Hence, the arrangement of r-proteins and rRNA into large ribonucleoprotein complexes requires dedicated mechanisms ensuring their encounter in the same compartment. To this end, r-proteins need to be safely delivered to the nucleus where they assemble with the rRNA. Beyond these initial challenges, the synthesis of ribosomes does not merely comprise the joining of r-proteins with rRNA, but occurs in a complex assembly line involving multiple maturation steps, including the processing and folding of rRNA. R-proteins usually have composite rRNA binding sites, with several different rRNA helices contributing to the full interaction. Not all of these interaction sites may already be accessible at the point when an r-protein is incorporated, necessitating that some of the r-protein-rRNA contacts are formed at later maturation stages. In our two recent studies, we investigated the ribosome assembly path of r-proteins in the yeast Saccharomyces cerevisiae using the small subunit r-protein S3 (Rps3) as a model. Our studies revealed intricate mechanisms to protect the protein, transport it into the nucleus, integrate it into pre-ribosomal precursor particles and promote its final stable association with 40S subunits.
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Affiliation(s)
- Brigitte Pertschy
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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53
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Abstract
Wobble uridines (U34) are generally modified in all species. U34 modifications can be essential in metazoans but are not required for viability in fungi. In this review, we provide an overview on the types of modifications and how they affect the physico-chemical properties of wobble uridines. We describe the molecular machinery required to introduce these modifications into tRNA posttranscriptionally and discuss how posttranslational regulation may affect the activity of the modifying enzymes. We highlight the activity of anticodon specific RNases that target U34 containing tRNA. Finally, we discuss how defects in wobble uridine modifications lead to phenotypes in different species. Importantly, this review will mainly focus on the cytoplasmic tRNAs of eukaryotes. A recent review has extensively covered their bacterial and mitochondrial counterparts.1
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Affiliation(s)
- Raffael Schaffrath
- a Institut für Biologie, FG Mikrobiologie , Universität Kassel , Germany
| | - Sebastian A Leidel
- b Max Planck Institute for Molecular Biomedicine , Germany.,c Cells-in-Motion Cluster of Excellence , University of Münster , Münster , Germany.,d Medical Faculty , University of Münster , Albert-Schweitzer-Campus 1, Münster , Germany
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54
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Johnson MC, Ghalei H, Doxtader KA, Karbstein K, Stroupe ME. Structural Heterogeneity in Pre-40S Ribosomes. Structure 2017; 25:329-340. [PMID: 28111018 DOI: 10.1016/j.str.2016.12.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/07/2016] [Accepted: 12/21/2016] [Indexed: 11/24/2022]
Abstract
Late-stage 40S ribosome assembly is a highly regulated dynamic process that occurs in the cytoplasm, alongside the full translation machinery. Seven assembly factors (AFs) regulate and facilitate maturation, but the mechanisms through which they work remain undetermined. Here, we present a series of structures of the immature small subunit (pre-40S) determined by three-dimensional (3D) cryoelectron microscopy with 3D sorting to assess the molecule's heterogeneity. These structures demonstrate an extensive structural heterogeneity of interface AFs that likely regulates subunit joining during 40S maturation. We also present structural models for the beak and the platform, two regions where the low resolution of previous studies did not allow for localization of AFs and the rRNA, respectively. These models are supported by biochemical analyses using point variants and suggest that maturation of the 18S 3' end is regulated by dissociation of the AF Dim1 from the subunit interface, consistent with previous biochemical analyses.
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Affiliation(s)
- Matthew C Johnson
- Department of Biological Science, Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA
| | - Homa Ghalei
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katelyn A Doxtader
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katrin Karbstein
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - M Elizabeth Stroupe
- Department of Biological Science, Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA.
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55
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Rosenberg LH, Cleveland JL, Roush WR, Duckett DR. CK1δ: an exploitable vulnerability in breast cancer. ANNALS OF TRANSLATIONAL MEDICINE 2017; 4:474. [PMID: 28090530 DOI: 10.21037/atm.2016.12.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - John L Cleveland
- Department of Tumor Biology, H. Lee Moffitt Cancer Center & Research, Institute, Tampa, FL, USA
| | - William R Roush
- Department of Chemistry, Scripps Florida, The Scripps Research Institute, Jupiter, FL, USA
| | - Derek R Duckett
- Department of Molecular Therapeutics, Scripps Florida, The Scripps Research Institute, Jupiter, FL, USA
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56
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Larburu N, Montellese C, O'Donohue MF, Kutay U, Gleizes PE, Plisson-Chastang C. Structure of a human pre-40S particle points to a role for RACK1 in the final steps of 18S rRNA processing. Nucleic Acids Res 2016; 44:8465-78. [PMID: 27530427 PMCID: PMC5041492 DOI: 10.1093/nar/gkw714] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/28/2016] [Accepted: 08/06/2016] [Indexed: 01/24/2023] Open
Abstract
Synthesis of ribosomal subunits in eukaryotes is a complex and tightly regulated process that has been mostly characterized in yeast. The discovery of a growing number of diseases linked to defects in ribosome biogenesis calls for a deeper understanding of these mechanisms and of the specificities of human ribosome maturation. We present the 19 Å resolution cryo-EM reconstruction of a cytoplasmic precursor to the human small ribosomal subunit, purified by using the tagged ribosome biogenesis factor LTV1 as bait. Compared to yeast pre-40S particles, this first three-dimensional structure of a human 40S subunit precursor shows noticeable differences with respect to the position of ribosome biogenesis factors and uncovers the early deposition of the ribosomal protein RACK1 during subunit maturation. Consistently, RACK1 is required for efficient processing of the 18S rRNA 3'-end, which might be related to its role in translation initiation. This first structural analysis of a human pre-ribosomal particle sets the grounds for high-resolution studies of conformational transitions accompanying ribosomal subunit maturation.
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MESH Headings
- Conserved Sequence
- Cryoelectron Microscopy
- Cytoplasm/metabolism
- GTP-Binding Proteins/metabolism
- HEK293 Cells
- HeLa Cells
- Humans
- Models, Molecular
- Neoplasm Proteins/metabolism
- Organelle Biogenesis
- Protein Binding
- RNA Processing, Post-Transcriptional/genetics
- RNA, Ribosomal, 18S/genetics
- Receptors for Activated C Kinase
- Receptors, Cell Surface/metabolism
- Ribosomal Proteins/metabolism
- Ribosome Subunits, Small, Eukaryotic/chemistry
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/ultrastructure
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- Natacha Larburu
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | | | - Marie-Françoise O'Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Ulrike Kutay
- Institut für Biochemie, ETH Zürich, CH-8093 Zurich, Switzerland
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
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57
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Ye Q, Ur SN, Su TY, Corbett KD. Structure of the Saccharomyces cerevisiae Hrr25:Mam1 monopolin subcomplex reveals a novel kinase regulator. EMBO J 2016; 35:2139-2151. [PMID: 27491543 DOI: 10.15252/embj.201694082] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 07/20/2016] [Indexed: 11/09/2022] Open
Abstract
In budding yeast, the monopolin complex mediates sister kinetochore cross-linking and co-orientation in meiosis I. The CK1δ kinase Hrr25 is critical for sister kinetochore co-orientation, but its roles are not well understood. Here, we present the structures of Hrr25 and its complex with the monopolin subunit Mam1. Hrr25 possesses a "central domain" that packs tightly against the kinase C-lobe, adjacent to the binding site for Mam1. Together, the Hrr25 central domain and Mam1 form a novel, contiguous embellishment to the Hrr25 kinase domain that affects Hrr25 conformational dynamics and enzyme kinetics. Mam1 binds a hydrophobic surface on the Hrr25 N-lobe that is conserved in CK1δ-family kinases, suggesting a role for this surface in recruitment and/or regulation of these enzymes throughout eukaryotes. Finally, using purified proteins, we find that Hrr25 phosphorylates the kinetochore receptor for monopolin, Dsn1. Together with our new structural insights into the fully assembled monopolin complex, this finding suggests that tightly localized Hrr25 activity modulates monopolin complex-kinetochore interactions through phosphorylation of both kinetochore and monopolin complex components.
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Affiliation(s)
- Qiaozhen Ye
- Ludwig Institute for Cancer Research, San Diego Branch, San Diego, La Jolla, CA, USA
| | - Sarah N Ur
- Ludwig Institute for Cancer Research, San Diego Branch, San Diego, La Jolla, CA, USA
| | - Tiffany Y Su
- Ludwig Institute for Cancer Research, San Diego Branch, San Diego, La Jolla, CA, USA
| | - Kevin D Corbett
- Ludwig Institute for Cancer Research, San Diego Branch, San Diego, La Jolla, CA, USA Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
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58
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Khoshnevis S, Askenasy I, Johnson MC, Dattolo MD, Young-Erdos CL, Stroupe ME, Karbstein K. The DEAD-box Protein Rok1 Orchestrates 40S and 60S Ribosome Assembly by Promoting the Release of Rrp5 from Pre-40S Ribosomes to Allow for 60S Maturation. PLoS Biol 2016; 14:e1002480. [PMID: 27280440 PMCID: PMC4900678 DOI: 10.1371/journal.pbio.1002480] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/10/2016] [Indexed: 12/25/2022] Open
Abstract
DEAD-box proteins are ubiquitous regulators of RNA biology. While commonly dubbed “helicases,” their activities also include duplex annealing, adenosine triphosphate (ATP)-dependent RNA binding, and RNA-protein complex remodeling. Rok1, an essential DEAD-box protein, and its cofactor Rrp5 are required for ribosome assembly. Here, we use in vivo and in vitro biochemical analyses to demonstrate that ATP-bound Rok1, but not adenosine diphosphate (ADP)-bound Rok1, stabilizes Rrp5 binding to 40S ribosomes. Interconversion between these two forms by ATP hydrolysis is required for release of Rrp5 from pre-40S ribosomes in vivo, thereby allowing Rrp5 to carry out its role in 60S subunit assembly. Furthermore, our data also strongly suggest that the previously described accumulation of snR30 upon Rok1 inactivation arises because Rrp5 release is blocked and implicate a previously undescribed interaction between Rrp5 and the DEAD-box protein Has1 in mediating snR30 accumulation when Rrp5 release from pre-40S subunits is blocked. During ribosomal biogenesis, Rrp5 is unusual in being required for assembly of both small and large subunits. This study demonstrates a role for ATP hydrolysis by the DEAD-box protein Rok1 in releasing Rrp5 from pre-40S subunits. Assembly of the small and large ribosomal subunits requires two separate machineries. The assembly factor Rrp5 is unusual in being one of only three proteins required for assembly of both subunits. While it binds cotranscriptionally during early stages of small subunit assembly, it departs with large subunit intermediates after the separation of these precursors. How Rrp5 switches from interacting with small subunit precursors to binding large subunit precursors remains unknown but is potentially important, as it could regulate the interplay between small and large subunit assembly. Here, we show that the DEAD-box protein Rok1, a member of a ubiquitous class of RNA-dependent ATPases, releases Rrp5 from assembling small subunits to allow for its function in large subunit assembly. We show that a complex of Rrp5, Rok1, and adenosine triphosphate (ATP) binds small subunits or mimics of ribosomal RNA more tightly than does a complex of Rrp5, Rok1, and adenosine diphosphate (ADP). In cells, interconversion between the ATP and the ADP-form of Rok1 is required for release of Rrp5 from nascent small subunits and for binding to assembling large subunits. Furthermore, we show that the release of snR30, which leads to formation of a large substructure on small subunits, also requires Rok1-mediated release of Rrp5.
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MESH Headings
- Adenosine Diphosphate/metabolism
- Adenosine Triphosphate/metabolism
- Binding Sites/genetics
- DEAD-box RNA Helicases/chemistry
- DEAD-box RNA Helicases/genetics
- DEAD-box RNA Helicases/metabolism
- Hydrolysis
- Models, Molecular
- Molecular Conformation
- Nuclear Proteins/chemistry
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Protein Binding
- Protein Domains
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Ribosome Subunits, Large, Eukaryotic/chemistry
- Ribosome Subunits, Large, Eukaryotic/genetics
- Ribosome Subunits, Large, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/chemistry
- Ribosome Subunits, Small, Eukaryotic/genetics
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
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Affiliation(s)
- Sohail Khoshnevis
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Isabel Askenasy
- Department of Biological Science and the Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
| | - Matthew C. Johnson
- Department of Biological Science and the Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
| | - Maria D. Dattolo
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, United States of America
- The Benjamin School, Palm Beach Gardens, Florida, United States of America
| | - Crystal L. Young-Erdos
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - M. Elizabeth Stroupe
- Department of Biological Science and the Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
- * E-mail: (MES); (KK)
| | - Katrin Karbstein
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, United States of America
- * E-mail: (MES); (KK)
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59
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Mitterer V, Murat G, Réty S, Blaud M, Delbos L, Stanborough T, Bergler H, Leulliot N, Kressler D, Pertschy B. Sequential domain assembly of ribosomal protein S3 drives 40S subunit maturation. Nat Commun 2016; 7:10336. [PMID: 26831757 PMCID: PMC4740875 DOI: 10.1038/ncomms10336] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 11/29/2015] [Indexed: 11/25/2022] Open
Abstract
Eukaryotic ribosomes assemble by association of ribosomal RNA with ribosomal proteins into nuclear precursor particles, which undergo a complex maturation pathway coordinated by non-ribosomal assembly factors. Here, we provide functional insights into how successive structural re-arrangements in ribosomal protein S3 promote maturation of the 40S ribosomal subunit. We show that S3 dimerizes and is imported into the nucleus with its N-domain in a rotated conformation and associated with the chaperone Yar1. Initial assembly of S3 with 40S precursors occurs via its C-domain, while the N-domain protrudes from the 40S surface. Yar1 is replaced by the assembly factor Ltv1, thereby fixing the S3 N-domain in the rotated orientation and preventing its 40S association. Finally, Ltv1 release, triggered by phosphorylation, and flipping of the S3 N-domain into its final position results in the stable integration of S3. Such a stepwise assembly may represent a new paradigm for the incorporation of ribosomal proteins. Ribosome biogenesis involves the hierarchical assembly of several proteins and RNA components. Here the authors describe a mechanism for ribosomal protein S3 incorporation into 40S ribosomal subunits that involves S3 dimerization and stepwise incorporation of two distinct S3 interaction domains coupled to release of ribosomal maturation factors.
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Affiliation(s)
- Valentin Mitterer
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Stéphane Réty
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Magali Blaud
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Lila Delbos
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Tamsyn Stanborough
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Helmut Bergler
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Nicolas Leulliot
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Brigitte Pertschy
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
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60
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Stokes JM, Brown ED. Chemical modulators of ribosome biogenesis as biological probes. Nat Chem Biol 2015; 11:924-32. [PMID: 26575239 DOI: 10.1038/nchembio.1957] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Accepted: 10/13/2015] [Indexed: 01/17/2023]
Abstract
Small-molecule inhibitors of protein biosynthesis have been instrumental in the dissection of the complexities of ribosome structure and function. Ribosome biogenesis, on the other hand, is a complex and largely enigmatic process for which there is a paucity of chemical probes. Indeed, ribosome biogenesis has been studied almost exclusively using genetic and biochemical approaches without the benefit of small-molecule inhibitors of this process. Here, we provide a perspective on the promise of chemical inhibitors of ribosome assembly for future research. We explore key obstacles that complicate the interpretation of studies aimed at perturbing ribosome biogenesis in vivo using genetic methods, and we argue that chemical inhibitors are especially powerful because they can be used to induce perturbations in a manner that obviates these difficulties. Thus, in combination with leading-edge biochemical and structural methods, chemical probes offer unique advantages toward elucidating the molecular events that define the assembly of ribosomes.
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Affiliation(s)
- Jonathan M Stokes
- Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Eric D Brown
- Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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61
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Abstract
The proteome of cells is synthesized by ribosomes, complex ribonucleoproteins that in eukaryotes contain 79-80 proteins and four ribosomal RNAs (rRNAs) more than 5,400 nucleotides long. How these molecules assemble together and how their assembly is regulated in concert with the growth and proliferation of cells remain important unanswered questions. Here, we review recently emerging principles to understand how eukaryotic ribosomal proteins drive ribosome assembly in vivo. Most ribosomal proteins assemble with rRNA cotranscriptionally; their association with nascent particles is strengthened as assembly proceeds. Each subunit is assembled hierarchically by sequential stabilization of their subdomains. The active sites of both subunits are constructed last, perhaps to prevent premature engagement of immature ribosomes with active subunits. Late-assembly intermediates undergo quality-control checks for proper function. Mutations in ribosomal proteins that affect mostly late steps lead to ribosomopathies, diseases that include a spectrum of cell type-specific disorders that often transition from hypoproliferative to hyperproliferative growth.
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Affiliation(s)
- Jesus de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocio/CSIC/Universidad de Sevilla, E-41013 Sevilla, Spain
- Departamento de Genetica, Universidad de Sevilla, E-41013 Sevilla, Spain
| | - Katrin Karbstein
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida 33458
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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62
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Nerurkar P, Altvater M, Gerhardy S, Schütz S, Fischer U, Weirich C, Panse VG. Eukaryotic Ribosome Assembly and Nuclear Export. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 319:107-40. [DOI: 10.1016/bs.ircmb.2015.07.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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