1
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Ayers TN, Woolford JL. Putting It All Together: The Roles of Ribosomal Proteins in Nucleolar Stages of 60S Ribosomal Assembly in the Yeast Saccharomyces cerevisiae. Biomolecules 2024; 14:975. [PMID: 39199362 PMCID: PMC11353139 DOI: 10.3390/biom14080975] [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: 07/17/2024] [Revised: 08/05/2024] [Accepted: 08/07/2024] [Indexed: 09/01/2024] Open
Abstract
Here we review the functions of ribosomal proteins (RPs) in the nucleolar stages of large ribosomal subunit assembly in the yeast Saccharomyces cerevisiae. We summarize the effects of depleting RPs on pre-rRNA processing and turnover, on the assembly of other RPs, and on the entry and exit of assembly factors (AFs). These results are interpreted in light of recent near-atomic-resolution cryo-EM structures of multiple assembly intermediates. Results are discussed with respect to each neighborhood of RPs and rRNA. We identify several key mechanisms related to RP behavior. Neighborhoods of RPs can assemble in one or more than one step. Entry of RPs can be triggered by molecular switches, in which an AF is replaced by an RP binding to the same site. To drive assembly forward, rRNA structure can be stabilized by RPs, including clamping rRNA structures or forming bridges between rRNA domains.
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Affiliation(s)
| | - John L. Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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2
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Li K, Zhang Q, Liu H, Wang F, Li A, Ding T, Mu Q, Zhao H, Wang P. Arabidopsis NOTCHLESS plays an important role in root and embryo development. PLANT SIGNALING & BEHAVIOR 2023; 18:2245616. [PMID: 37573563 PMCID: PMC10424599 DOI: 10.1080/15592324.2023.2245616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 08/15/2023]
Abstract
Ribosome biogenesis is a fundamental process in eukaryotic cells. NOTCHLESS (NLE) is involved in 60S ribosome biogenesis in yeast, but its role in Arabidopsis (A. thaliana) remains exclusive. Here, we found that Arabidopsis NLE (AtNLE) is highly conservative in phylogeny, which encoding a WD40-repeat protein. AtNLE is expressed in actively dividing tissues. AtNLE-GFP is localized in the nucleus. AtNLE physically interacts with the MIDAS domain of AtMDN1, a protein involved in the biogenesis of the 60S ribosomal subunit in Arabidopsis. The underexpressing mutant nle-2 shows short roots and reduced cell number in the root meristem. In addition, the null mutant nle-1 is embryo lethal, and defective embryos are arrested at the early globular stage. This work suggests that AtNLE interacts with AtMDN1, and AtNLE functions in root and embryo development.
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Affiliation(s)
- Ke Li
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Qingtian Zhang
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Huiping Liu
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Fengxia Wang
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Ao Li
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Tingting Ding
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
- Shandong Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Jinan, China
| | - Qian Mu
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Hongjun Zhao
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
| | - Pengfei Wang
- Shandong Academy of Grape, Shandong Academy of Agricultural Sciences, Jinan, PR China
- Shandong Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Jinan, China
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3
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Thoms M, Lau B, Cheng J, Fromm L, Denk T, Kellner N, Flemming D, Fischer P, Falquet L, Berninghausen O, Beckmann R, Hurt E. Structural insights into coordinating 5S RNP rotation with ITS2 pre-RNA processing during ribosome formation. EMBO Rep 2023; 24:e57984. [PMID: 37921038 DOI: 10.15252/embr.202357984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 10/11/2023] [Accepted: 10/14/2023] [Indexed: 11/04/2023] Open
Abstract
The rixosome defined in Schizosaccharomyces pombe and humans performs diverse roles in pre-ribosomal RNA processing and gene silencing. Here, we isolate and describe the conserved rixosome from Chaetomium thermophilum, which consists of two sub-modules, the sphere-like Rix1-Ipi3-Ipi1 and the butterfly-like Las1-Grc3 complex, connected by a flexible linker. The Rix1 complex of the rixosome utilizes Sda1 as landing platform on nucleoplasmic pre-60S particles to wedge between the 5S rRNA tip and L1-stalk, thereby facilitating the 180° rotation of the immature 5S RNP towards its mature conformation. Upon rixosome positioning, the other sub-module with Las1 endonuclease and Grc3 polynucleotide-kinase can reach a strategic position at the pre-60S foot to cleave and 5' phosphorylate the nearby ITS2 pre-rRNA. Finally, inward movement of the L1 stalk permits the flexible Nop53 N-terminus with its AIM motif to become positioned at the base of the L1-stalk to facilitate Mtr4 helicase-exosome participation for completing ITS2 removal. Thus, the rixosome structure elucidates the coordination of two central ribosome biogenesis events, but its role in gene silencing may adapt similar strategies.
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Affiliation(s)
- Matthias Thoms
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Benjamin Lau
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Jingdong Cheng
- Minhang Hospital & Institutes of Biomedical Sciences, Shanghai Key Laboratory of Medical Epigenetics, Fudan University, Shanghai, China
| | - Lisa Fromm
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Timo Denk
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nikola Kellner
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Dirk Flemming
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Paulina Fischer
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Laurent Falquet
- University of Fribourg and Swiss Institute of Bioinformatics, Fribourg, Switzerland
| | | | - Roland Beckmann
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
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4
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LaPeruta AJ, Hedayati S, Micic J, Fitzgerald F, Kim D, Oualline G, Woolford JL. Yeast ribosome biogenesis factors Puf6 and Nog2 and ribosomal proteins uL2 and eL43 act in concert to facilitate the release of nascent large ribosomal subunits from the nucleolus. Nucleic Acids Res 2023; 51:11277-11290. [PMID: 37811893 PMCID: PMC10639061 DOI: 10.1093/nar/gkad794] [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: 04/15/2022] [Revised: 09/11/2023] [Accepted: 09/22/2023] [Indexed: 10/10/2023] Open
Abstract
Large ribosomal subunit precursors (pre-LSUs) are primarily synthesized in the nucleolus. At an undetermined step in their assembly, they are released into the nucleoplasm. Structural models of yeast pre-LSUs at various stages of assembly have been collected using cryo-EM. However, which cryo-EM model is closest to the final nucleolar intermediate of the LSU has yet to be determined. To elucidate the mechanisms of the release of pre-LSUs from the nucleolus, we assayed effects of depleting or knocking out two yeast ribosome biogenesis factors (RiBi factors), Puf6 and Nog2, and two ribosomal proteins, uL2 and eL43. These proteins function during or stabilize onto pre-LSUs between the late nucleolar stages to early nucleoplasmic stages of ribosome biogenesis. By characterizing the phenotype of these four mutants, we determined that a particle that is intermediate between the cryo-EM model State NE1 and State NE2 likely represents the final nucleolar assembly intermediate of the LSU. We conclude that the release of the RiBi factors Nip7, Nop2 and Spb1 and the subsequent stabilization of rRNA domains IV and V may be key triggers for the release of pre-LSUs from the nucleolus.
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Affiliation(s)
- Amber J LaPeruta
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Stefanie Hedayati
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Jelena Micic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Fiona Fitzgerald
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - David Kim
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Grace Oualline
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - John L Woolford
- 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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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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7
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Parker MD, Karbstein K. Quality control ensures fidelity in ribosome assembly and cellular health. J Cell Biol 2023; 222:e202209115. [PMID: 36790396 PMCID: PMC9960125 DOI: 10.1083/jcb.202209115] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [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
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8
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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: 43] [Impact Index Per Article: 43.0] [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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9
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Cruz VE, Sekulski K, Peddada N, Sailer C, Balasubramanian S, Weirich CS, Stengel F, Erzberger JP. Sequence-specific remodeling of a topologically complex RNP substrate by Spb4. Nat Struct Mol Biol 2022; 29:1228-1238. [PMID: 36482249 PMCID: PMC10680166 DOI: 10.1038/s41594-022-00874-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 10/14/2022] [Indexed: 12/13/2022]
Abstract
DEAD-box ATPases are ubiquitous enzymes essential in all aspects of RNA biology. However, the limited in vitro catalytic activities described for these enzymes are at odds with their complex cellular roles, most notably in driving large-scale RNA remodeling steps during the assembly of ribonucleoproteins (RNPs). We describe cryo-EM structures of 60S ribosomal biogenesis intermediates that reveal how context-specific RNA unwinding by the DEAD-box ATPase Spb4 results in extensive, sequence-specific remodeling of rRNA secondary structure. Multiple cis and trans interactions stabilize Spb4 in a post-catalytic, high-energy intermediate that drives the organization of the three-way junction at the base of rRNA domain IV. This mechanism explains how limited strand separation by DEAD-box ATPases is leveraged to provide non-equilibrium directionality and ensure efficient and accurate RNP assembly.
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Affiliation(s)
- Victor Emmanuel Cruz
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Kamil Sekulski
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Nagesh Peddada
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Carolin Sailer
- Department of Biology, University of Konstanz, Konstanz, Germany
- Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
- Department of Biomedical Sciences, University of Copenhagen, København, Denmark
| | - Sahana Balasubramanian
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
- Cell Biology & Molecular Physiology Department, University of Pittsburgh, Pittsburgh, PA, USA
| | - Christine S Weirich
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA
| | - Florian Stengel
- Department of Biology, University of Konstanz, Konstanz, Germany
- Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Jan P Erzberger
- Department of Biophysics, UT Southwestern Medical Center - ND10.124B, Dallas, TX, USA.
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10
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Ma C, Wu D, Chen Q, Gao N. Structural dynamics of AAA + ATPase Drg1 and mechanism of benzo-diazaborine inhibition. Nat Commun 2022; 13:6765. [PMID: 36351914 PMCID: PMC9646744 DOI: 10.1038/s41467-022-34511-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 10/27/2022] [Indexed: 11/11/2022] Open
Abstract
The type II AAA + ATPase Drg1 is a ribosome assembly factor, functioning to release Rlp24 from the pre-60S particle just exported from nucleus, and its activity in can be inhibited by a drug molecule diazaborine. However, molecular mechanisms of Drg1-mediated Rlp24 removal and diazaborine-mediated inhibition are not fully understood. Here, we report Drg1 structures in different nucleotide-binding and benzo-diazaborine treated states. Drg1 hexamers transits between two extreme conformations (planar or helical arrangement of protomers). By forming covalent adducts with ATP molecules in both ATPase domain, benzo-diazaborine locks Drg1 hexamers in a symmetric and non-productive conformation to inhibits both inter-protomer and inter-ring communication of Drg1 hexamers. We also obtained a substrate-engaged mutant Drg1 structure, in which conserved pore-loops form a spiral staircase to interact with the polypeptide through a sequence-independent manner. Structure-based mutagenesis data highlight the functional importance of the pore-loop, the D1-D2 linker and the inter-subunit signaling motif of Drg1, which share similar regulatory mechanisms with p97. Our results suggest that Drg1 may function as an unfoldase that threads a substrate protein within the pre-60S particle.
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Affiliation(s)
- Chengying Ma
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, 100871 Beijing, China ,Changping Laboratory, 102206 Beijing, China
| | - Damu Wu
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, 100871 Beijing, China
| | - Qian Chen
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, 100871 Beijing, China
| | - Ning Gao
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, 100871 Beijing, China ,Changping Laboratory, 102206 Beijing, China ,grid.11135.370000 0001 2256 9319National Biomedical Imaging Center, Peking University, 100871 Beijing, China
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11
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Wang Y, Sun Z, Wang L, Chen L, Ma L, Lv J, Qiao K, Fan S, Ma Q. GhBOP1 as a Key Factor of Ribosomal Biogenesis: Development of Wrinkled Leaves in Upland Cotton. Int J Mol Sci 2022; 23:ijms23179942. [PMID: 36077339 PMCID: PMC9456263 DOI: 10.3390/ijms23179942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Block of proliferation 1 (BOP1) is a key protein that helps in the maturation of ribosomes and promotes the progression of the cell cycle. However, its role in the leaf morphogenesis of cotton remains unknown. Herein, we report and study the function of GhBOP1 isolated from Gossypium hirsutum. The sequence alignment revealed that BOP1 protein was highly conserved among different species. The yeast two-hybrid experiments, bimolecular fluorescence complementation, and luciferase complementation techniques revealed that GhBOP1 interact with GhPES and GhWDR12. Subcellular localization experiments revealed that GhBOP1, GhPES and GhWDR12 were localized at the nucleolus. Suppression of GhBOP1 transcripts resulted in the uneven bending of leaf margins and the presence of young wrinkled leaves by virus-induced gene silencing assay. Abnormal palisade arrangements and the presence of large upper epidermal cells were observed in the paraffin sections of the wrinkled leaves. Meanwhile, a jasmonic acid-related gene, GhOPR3, expression was increased. In addition, a negative effect was exerted on the cell cycle and the downregulation of the auxin-related genes was also observed. These results suggest that GhBOP1 plays a critical role in the development of wrinkled cotton leaves, and the process is potentially modulated through phytohormone signaling.
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Affiliation(s)
- Yanwen Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
| | - Zhimao Sun
- College of Life Sciences, Shaanxi Normal University, Xi’an 710062, China
| | - Long Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
| | - Lingling Chen
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
| | - Lina Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
| | - Jiaoyan Lv
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
| | - Kaikai Qiao
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
| | - Shuli Fan
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
- Hainan Yazhou Bay Seed Lab, Sanya 572000, China
- National Nanfan Research Institute (Sanya), Chinese Academy of Agricultural Sciences, Sanya 572000, China
- Correspondence: (S.F.); (Q.M.)
| | - Qifeng Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455099, China
- Correspondence: (S.F.); (Q.M.)
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12
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Moraleva AA, Deryabin AS, Rubtsov YP, Rubtsova MP, Dontsova OA. Eukaryotic Ribosome Biogenesis: The 60S Subunit. Acta Naturae 2022; 14:39-49. [PMID: 35925480 PMCID: PMC9307984 DOI: 10.32607/actanaturae.11541] [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: 07/29/2021] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Ribosome biogenesis is consecutive coordinated maturation of ribosomal precursors in the nucleolus, nucleoplasm, and cytoplasm. The formation of mature ribosomal subunits involves hundreds of ribosomal biogenesis factors that ensure ribosomal RNA processing, tertiary structure, and interaction with ribosomal proteins. Although the main features and stages of ribosome biogenesis are conservative among different groups of eukaryotes, this process in human cells has become more complicated due to the larger size of the ribosomes and pre-ribosomes and intricate regulatory pathways affecting 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. A previous part of this review summarized recent data on the processing of the primary rRNA transcript and compared the maturation of the small 40S subunit in yeast and human cells. This part of the review focuses on the biogenesis of the large 60S subunit of eukaryotic ribosomes.
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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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13
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Temaj G, Saha S, Dragusha S, Ejupi V, Buttari B, Profumo E, Beqa L, Saso L. Ribosomopathies and cancer: pharmacological implications. Expert Rev Clin Pharmacol 2022; 15:729-746. [PMID: 35787725 DOI: 10.1080/17512433.2022.2098110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION The ribosome is a ribonucleoprotein organelle responsible for protein synthesis, and its biogenesis is a highly coordinated process that involves many macromolecular components. Any acquired or inherited impairment in ribosome biogenesis or ribosomopathies is associated with the development of different cancers and rare genetic diseases. Interference with multiple steps of protein synthesis has been shown to promote tumor cell death. AREAS COVERED We discuss the current insights about impaired ribosome biogenesis and their secondary consequences on protein synthesis, transcriptional and translational responses, proteotoxic stress, and other metabolic pathways associated with cancer and rare diseases. Studies investigating the modulation of different therapeutic chemical entities targeting cancer in in vitro and in vivo models have also been detailed. EXPERT OPINION Despite the association between inherited mutations affecting ribosome biogenesis and cancer biology, the development of therapeutics targeting the essential cellular machinery has only started to emerge. New chemical entities should be designed to modulate different checkpoints (translating oncoproteins, dysregulation of specific ribosome-assembly machinery, ribosomal stress, and rewiring ribosomal functions). Although safe and effective therapies are lacking, consideration should also be given to using existing drugs alone or in combination for long-term safety, with known risks for feasibility in clinical trials and synergistic effects.
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Affiliation(s)
| | - Sarmistha Saha
- Department of Cardiovascular, Endocrine-metabolic Diseases, and Aging, Italian National Institute of Health, Rome, Italy
| | | | - Valon Ejupi
- College UBT, Faculty of Pharmacy, Prishtina, Kosovo
| | - Brigitta Buttari
- Department of Cardiovascular, Endocrine-metabolic Diseases, and Aging, Italian National Institute of Health, Rome, Italy
| | - Elisabetta Profumo
- Department of Cardiovascular, Endocrine-metabolic Diseases, and Aging, Italian National Institute of Health, Rome, Italy
| | - Lule Beqa
- College UBT, Faculty of Pharmacy, Prishtina, Kosovo
| | - Luciano Saso
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Italy
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14
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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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15
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Micic J, Rodríguez-Galán O, Babiano R, Fitzgerald F, Fernández-Fernández J, Zhang Y, Gao N, Woolford JL, de la Cruz J. Ribosomal protein eL39 is important for maturation of the nascent polypeptide exit tunnel and proper protein folding during translation. Nucleic Acids Res 2022; 50:6453-6473. [PMID: 35639884 PMCID: PMC9226512 DOI: 10.1093/nar/gkac366] [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: 08/19/2021] [Revised: 04/04/2022] [Accepted: 05/12/2022] [Indexed: 11/29/2022] Open
Abstract
During translation, nascent polypeptide chains travel from the peptidyl transferase center through the nascent polypeptide exit tunnel (NPET) to emerge from 60S subunits. The NPET includes portions of five of the six 25S/5.8S rRNA domains and ribosomal proteins uL4, uL22, and eL39. Internal loops of uL4 and uL22 form the constriction sites of the NPET and are important for both assembly and function of ribosomes. Here, we investigated the roles of eL39 in tunnel construction, 60S biogenesis, and protein synthesis. We show that eL39 is important for proper protein folding during translation. Consistent with a delay in processing of 27S and 7S pre-rRNAs, eL39 functions in pre-60S assembly during middle nucleolar stages. Our biochemical assays suggest the presence of eL39 in particles at these stages, although it is not visualized in them by cryo-electron microscopy. This indicates that eL39 takes part in assembly even when it is not fully accommodated into the body of pre-60S particles. eL39 is also important for later steps of assembly, rotation of the 5S ribonucleoprotein complex, likely through long range rRNA interactions. Finally, our data strongly suggest the presence of alternative pathways of ribosome assembly, previously observed in the biogenesis of bacterial ribosomal subunits.
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Affiliation(s)
- Jelena Micic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Olga Rodríguez-Galán
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Reyes Babiano
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Fiona Fitzgerald
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - José Fernández-Fernández
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Yunyang Zhang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Centre for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Centre for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain.,Departamento de Genética, Universidad de Sevilla, Seville, Spain
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16
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Ghamari R, Ahmadikhah A, Tohidfar M, Bakhtiarizadeh MR. RNA-Seq Analysis of Magnaporthe grisea Transcriptome Reveals the High Potential of ZnO Nanoparticles as a Nanofungicide. FRONTIERS IN PLANT SCIENCE 2022; 13:896283. [PMID: 35755666 PMCID: PMC9230574 DOI: 10.3389/fpls.2022.896283] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/20/2022] [Indexed: 06/07/2023]
Abstract
Magnaporthe grisea is one of the most destructive pathogen that encounters a challenge to rice production around the worldwide. The unique properties of ZnO nanoparticles (NPs), have high attractiveness as nanofungicide. In the present study, the response of fungi to ZnO NPs was evaluated using RNA sequencing (RNA-seq). Two different aligners (STAR and Hisat2) were used for aligning the clean reads, and the DEseq2 package was used to identify the differentially expressed genes (DEGs). In total, 1,438 and 761 fungal genes were significantly up- and down-regulated in response to ZnO NPs, respectively. The DEGs were subjected to functional enrichment analysis to identify significantly enriched biological pathways. Functional enrichment analysis revealed that "cell membrane components," "ion (calcium) transmembrane transporter activity," "steroid biosynthesis pathway" and "catalytic activity" were the contributed terms to fungal response mechanisms. The genes involved in aflatoxin efflux pumps and ribosome maturation were among the genes showing significant up- and down-regulation after ZnO NPs application. To confirm the obtained RNA-seq results, the expression of six randomly selected genes were evaluated using q-RT-PCR. Overall, the RNA-seq results suggest that ZnO NPs primarily act on the fungal cell membrane, but accumulation of ROS inside the cell induces oxidative stress, the fungal catalytic system is disrupted, resulting into the inhibition of ROS scavenging and eventually, to the death of fungal cells. Our findings provide novel insights into the effect of ZnO NPs as a promising nanofungicide for effective control of rice blast disease.
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Affiliation(s)
- Reza Ghamari
- Department of Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
| | - Asadollah Ahmadikhah
- Department of Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
| | - Masoud Tohidfar
- Department of Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
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17
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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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18
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Mickolajczyk KJ, Olinares PDB, Chait BT, Liu S, Kapoor TM. The MIDAS domain of AAA mechanoenzyme Mdn1 forms catch bonds with two different substrates. eLife 2022; 11:73534. [PMID: 35147499 PMCID: PMC8837202 DOI: 10.7554/elife.73534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 01/19/2022] [Indexed: 12/21/2022] Open
Abstract
Catch bonds are a form of mechanoregulation wherein protein-ligand interactions are strengthened by the application of dissociative tension. Currently, the best-characterized examples of catch bonds are between single protein-ligand pairs. The essential AAA (ATPase associated with diverse cellular activities) mechanoenzyme Mdn1 drives at least two separate steps in ribosome biogenesis, using its MIDAS domain to extract the ubiquitin-like (UBL) domain-containing proteins Rsa4 and Ytm1 from ribosomal precursors. However, it must subsequently release these assembly factors to reinitiate the enzymatic cycle. The mechanism underlying the switching of the MIDAS-UBL interaction between strongly and weakly bound states is unknown. Here, we use optical tweezers to investigate the force dependence of MIDAS-UBL binding. Parallel experiments with Rsa4 and Ytm1 show that forces up to ~4 pN, matching the magnitude of force produced by AAA proteins similar to Mdn1, enhance the MIDAS domain binding lifetime up to 10-fold, and higher forces accelerate dissociation. Together, our studies indicate that Mdn1's MIDAS domain can form catch bonds with more than one UBL substrate, and provide insights into how mechanoregulation may contribute to the Mdn1 enzymatic cycle during ribosome biogenesis.
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Affiliation(s)
- Keith J Mickolajczyk
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, United States
| | - Paul Dominic B Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, United States
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, United States
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19
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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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20
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Bagatelli FFM, de Luna Vitorino FN, da Cunha JPC, Oliveira CC. The ribosome assembly factor Nop53 has a structural role in the formation of nuclear pre-60S intermediates, affecting late maturation events. Nucleic Acids Res 2021; 49:7053-7074. [PMID: 34125911 PMCID: PMC8266606 DOI: 10.1093/nar/gkab494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/18/2021] [Accepted: 05/24/2021] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic ribosome biogenesis is an elaborate process during which ribosomal proteins assemble with the pre-rRNA while it is being processed and folded. Hundreds of assembly factors (AF) are required and transiently recruited to assist the sequential remodeling events. One of the most intricate ones is the stepwise removal of the internal transcribed spacer 2 (ITS2), between the 5.8S and 25S rRNAs, that constitutes together with five AFs the pre-60S ‘foot’. In the transition from nucleolus to nucleoplasm, Nop53 replaces Erb1 at the basis of the foot and recruits the RNA exosome for the ITS2 cleavage and foot disassembly. Here we comprehensively analyze the impact of Nop53 recruitment on the pre-60S compositional changes. We show that depletion of Nop53, different from nop53 mutants lacking the exosome-interacting motif, not only causes retention of the unprocessed foot in late pre-60S intermediates but also affects the transition from nucleolar state E particle to subsequent nuclear stages. Additionally, we reveal that Nop53 depletion causes the impairment of late maturation events such as Yvh1 recruitment. In light of recently described pre-60S cryo-EM structures, our results provide biochemical evidence for the structural role of Nop53 rearranging and stabilizing the foot interface to assist the Nog2 particle formation.
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Affiliation(s)
- Felipe F M Bagatelli
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Francisca N de Luna Vitorino
- Laboratory of Cell Cycle, Butantan Institute, São Paulo, SP 05503-900, Brazil.,Center of Toxins, Immune-Response and Cell Signaling, Butantan Institute, São Paulo, SP 05503-900, Brazil
| | - Julia P C da Cunha
- Laboratory of Cell Cycle, Butantan Institute, São Paulo, SP 05503-900, Brazil.,Center of Toxins, Immune-Response and Cell Signaling, Butantan Institute, São Paulo, SP 05503-900, Brazil
| | - Carla C Oliveira
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP 05508-000, Brazil
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21
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Martín-Villanueva S, Gutiérrez G, Kressler D, de la Cruz J. Ubiquitin and Ubiquitin-Like Proteins and Domains in Ribosome Production and Function: Chance or Necessity? Int J Mol Sci 2021; 22:ijms22094359. [PMID: 33921964 PMCID: PMC8122580 DOI: 10.3390/ijms22094359] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/11/2022] Open
Abstract
Ubiquitin is a small protein that is highly conserved throughout eukaryotes. It operates as a reversible post-translational modifier through a process known as ubiquitination, which involves the addition of one or several ubiquitin moieties to a substrate protein. These modifications mark proteins for proteasome-dependent degradation or alter their localization or activity in a variety of cellular processes. In most eukaryotes, ubiquitin is generated by the proteolytic cleavage of precursor proteins in which it is fused either to itself, constituting a polyubiquitin precursor, or as a single N-terminal moiety to ribosomal proteins, which are practically invariably eL40 and eS31. Herein, we summarize the contribution of the ubiquitin moiety within precursors of ribosomal proteins to ribosome biogenesis and function and discuss the biological relevance of having maintained the explicit fusion to eL40 and eS31 during evolution. There are other ubiquitin-like proteins, which also work as post-translational modifiers, among them the small ubiquitin-like modifier (SUMO). Both ubiquitin and SUMO are able to modify ribosome assembly factors and ribosomal proteins to regulate ribosome biogenesis and function. Strikingly, ubiquitin-like domains are also found within two ribosome assembly factors; hence, the functional role of these proteins will also be highlighted.
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Affiliation(s)
- Sara Martín-Villanueva
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41009 Seville, Spain;
- Departamento de Genética, Universidad de Sevilla, 41013 Seville, Spain;
| | - Gabriel Gutiérrez
- Departamento de Genética, Universidad de Sevilla, 41013 Seville, Spain;
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland
- Correspondence: (D.K.); (J.d.l.C.); Tel.: +41-26-300-86-45 (D.K.); +34-955-923-126 (J.d.l.C.)
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41009 Seville, Spain;
- Departamento de Genética, Universidad de Sevilla, 41013 Seville, Spain;
- Correspondence: (D.K.); (J.d.l.C.); Tel.: +41-26-300-86-45 (D.K.); +34-955-923-126 (J.d.l.C.)
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22
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Frazier MN, Pillon MC, Kocaman S, Gordon J, Stanley RE. Structural overview of macromolecular machines involved in ribosome biogenesis. Curr Opin Struct Biol 2021; 67:51-60. [PMID: 33099228 PMCID: PMC8058114 DOI: 10.1016/j.sbi.2020.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 12/17/2022]
Abstract
The production of ribosomes is essential for ensuring the translational capacity of cells. Because of its high energy demand ribosome production is subject to stringent cellular controls. Hundreds of ribosome assembly factors are required to facilitate assembly of nascent ribosome particles with high fidelity. Many ribosome assembly factors organize into macromolecular machines that drive complex steps of the production pathway. Recent advances in structural biology, in particular cryo-EM, have provided detailed information about the structure and function of these higher order enzymatic assemblies. Here, we summarize recent structures revealing molecular insight into these macromolecular machines with an emphasis on the interplay between discrete active sites.
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Affiliation(s)
- Meredith N Frazier
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Monica C Pillon
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Seda Kocaman
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Jacob Gordon
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Robin E Stanley
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA.
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23
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Li K, Zhou X, Sun X, Li G, Hou L, Zhao S, Zhao C, Ma C, Li P, Wang X. Coordination between MIDASIN 1-mediated ribosome biogenesis and auxin modulates plant development. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:2501-2513. [PMID: 33476386 DOI: 10.1093/jxb/erab025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
Ribosomes are required for plant growth and development, and ribosome biogenesis-deficient mutants generally display auxin-related phenotypes. Although the relationship between ribosome dysfunction and auxin is known, many aspects of this subject remain to be understood. We previously reported that MIDASIN 1 (MDN1) is an essential pre-60S ribosome biogenesis factor (RBF) in Arabidopsis. In this study, we further characterized the aberrant auxin-related phenotypes of mdn1-1, a weak mutant allele of MDN1. Auxin response is disturbed in both shoots and roots of mdn1-1, as indicated by the DR5:GUS reporter. By combining transcriptome profiling analysis and reporter gene detection, we found that expression of genes involved in auxin biosynthesis, transport, and signaling is changed in mdn1-1. Furthermore, MDN1 deficiency affects the post-transcriptional regulation and protein distribution of PIN-FORMED 2 (PIN2, an auxin efflux facilitator) in mdn1-1 roots. These results indicate that MDN1 is required for maintaining the auxin system. More interestingly, MDN1 is an auxin-responsive gene, and its promoter can be targeted by multiple AUXIN RESPONSE FACTORs (ARFs), including ARF7 and ARF19, in vitro. Indeed, in arf7 arf19, the auxin sensitivity of MDN1 expression is significantly reduced. Together, our results reveal a coordination mechanism between auxin and MDN1-dependent ribosome biogenesis for regulating plant development.
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Affiliation(s)
- Ke Li
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
- College of Life Science, Shandong University, Qingdao 266237, PR China
| | - Ximeng Zhou
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Xueping Sun
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Guanghui Li
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Lei Hou
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Shuzhen Zhao
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Chuanzhi Zhao
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Changle Ma
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Pengcheng Li
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Xingjun Wang
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences; Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
- College of Life Science, Shandong University, Qingdao 266237, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
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24
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Ogawa LM, Buhagiar AF, Abriola L, Leland BA, Surovtseva YV, Baserga SJ. Increased numbers of nucleoli in a genome-wide RNAi screen reveal proteins that link the cell cycle to RNA polymerase I transcription. Mol Biol Cell 2021; 32:956-973. [PMID: 33689394 PMCID: PMC8108525 DOI: 10.1091/mbc.e20-10-0670] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nucleoli are dynamic nuclear condensates in eukaryotic cells that originate through ribosome biogenesis at loci that harbor the ribosomal DNA. These loci are known as nucleolar organizer regions (NORs), and there are 10 in a human diploid genome. While there are 10 NORs, however, the number of nucleoli observed in cells is variable. Furthermore, changes in number are associated with disease, with increased numbers and size common in aggressive cancers. In the near-diploid human breast epithelial cell line, MCF10A, the most frequently observed number of nucleoli is two to three per cell. Here, to identify novel regulators of ribosome biogenesis we used high-throughput quantitative imaging of MCF10A cells to identify proteins that, when depleted, increase the percentage of nuclei with ≥5 nucleoli. Unexpectedly, this unique screening approach led to identification of proteins associated with the cell cycle. Functional analysis on a subset of hits further revealed not only proteins required for progression through the S and G2/M phase, but also proteins required explicitly for the regulation of RNA polymerase I transcription and protein synthesis. Thus, results from this screen for increased nucleolar number highlight the significance of the nucleolus in human cell cycle regulation, linking RNA polymerase I transcription to cell cycle progression.
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Affiliation(s)
- Lisa M Ogawa
- Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, CT 06520
| | - Amber F Buhagiar
- Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, CT 06520
| | - Laura Abriola
- Yale Center for Molecular Discovery, Yale University, West Haven, CT 06516
| | - Bryan A Leland
- Yale Center for Molecular Discovery, Yale University, West Haven, CT 06516
| | - Yulia V Surovtseva
- Yale Center for Molecular Discovery, Yale University, West Haven, CT 06516
| | - Susan J Baserga
- Department of Molecular Biophysics & Biochemistry, Yale University School of Medicine, New Haven, CT 06520.,Department of Genetics, Yale University School of Medicine, New Haven, CT 06520.,Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520
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25
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Gallegos KM, Patel JR, Llopis SD, Walker RR, Davidson AM, Zhang W, Zhang K, Tilghman SL. Quantitative Proteomic Profiling Identifies a Potential Novel Chaperone Marker in Resistant Breast Cancer. Front Oncol 2021; 11:540134. [PMID: 33718123 PMCID: PMC7951058 DOI: 10.3389/fonc.2021.540134] [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] [Received: 03/03/2020] [Accepted: 01/06/2021] [Indexed: 12/12/2022] Open
Abstract
Development of aromatase inhibitor resistant breast cancer among postmenopausal women continues to be a major clinical obstacle. Previously, our group demonstrated that as breast cancer cells transition from hormone-dependent to hormone-independent, they are associated with increased growth factor signaling, enhanced cellular motility, and the epithelial to mesenchymal transition (EMT). Given the complexity of cancer stem cells (CSC) and their implications on endocrine resistance and EMT, we sought to understand their contribution towards the development of aromatase inhibitor resistant breast cancer. Cells cultured three dimensionally as mammospheres are enriched for CSCs and more accurately recapitulates tumors in vivo. Therefore, a global proteomic analysis was conducted using letrozole resistant breast cancer cells (LTLT-Ca) mammospheres and compared to their adherent counterparts. Results demonstrated over 1000 proteins with quantitative abundance ratios were identified. Among the quantified proteins, 359 were significantly altered (p < 0.05), where 173 were upregulated and 186 downregulated (p < 0.05, fold change >1.20). Notably, midasin, a chaperone protein required for maturation and nuclear export of the pre-60S ribosome was increased 35-fold. Protein expression analyses confirmed midasin is ubiquitously expressed in normal tissue but is overexpressed in lobular and ductal breast carcinoma tissue as well as ER+ and ER- breast cancer cell lines. Functional enrichment analyses indicated that 19 gene ontology terms and one KEGG pathway were over-represented by the down-regulated proteins and both were associated with protein synthesis. Increased midasin was strongly correlated with decreased relapse free survival in hormone independent breast cancer. For the first time, we characterized the global proteomic signature of CSC-enriched letrozole-resistant cells associated with protein synthesis, which may implicate a role for midasin in endocrine resistance.
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Affiliation(s)
- Karen M Gallegos
- Division of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Jankiben R Patel
- Division of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Shawn D Llopis
- Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, New Orleans, LA, United States
| | - Rashidra R Walker
- Division of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - A Michael Davidson
- Division of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Wensheng Zhang
- Division of Mathematical and Physical Sciences, Department of Computer Science, College of Arts and Sciences, Xavier University of Louisiana, New Orleans, LA, United States
| | - Kun Zhang
- Division of Mathematical and Physical Sciences, Department of Computer Science, College of Arts and Sciences, Xavier University of Louisiana, New Orleans, LA, United States
| | - Syreeta L Tilghman
- Division of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
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26
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The composition and turnover of the Arabidopsis thaliana 80S cytosolic ribosome. Biochem J 2021; 477:3019-3032. [PMID: 32744327 PMCID: PMC7452503 DOI: 10.1042/bcj20200385] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/26/2020] [Accepted: 08/03/2020] [Indexed: 12/13/2022]
Abstract
Cytosolic 80S ribosomes contain proteins of the mature cytosolic ribosome (r-proteins) as well as proteins with roles in ribosome biogenesis, protein folding or modification. Here, we refined the core r-protein composition in Arabidopsis thaliana by determining the abundance of different proteins during enrichment of ribosomes from cell cultures using peptide mass spectrometry. The turnover rates of 26 40S subunit r-proteins and 29 60S subunit r-proteins were also determined, showing that half of the ribosome population is replaced every 3–4 days. Three enriched proteins showed significantly shorter half-lives; a protein annotated as a ribosomal protein uL10 (RPP0D, At1g25260) with a half-life of 0.5 days and RACK1b and c with half-lives of 1–1.4 days. The At1g25260 protein is a homologue of the human Mrt4 protein, a trans-acting factor in the assembly of the pre-60S particle, while RACK1 has known regulatory roles in cell function beyond its role in the 40S subunit. Our experiments also identified 58 proteins that are not from r-protein families but co-purify with ribosomes and co-express with r-proteins; 26 were enriched more than 10-fold during ribosome enrichment. Some of these enriched proteins have known roles in translation, while others are newly proposed ribosome-associated factors in plants. This analysis provides an improved understanding of A. thaliana ribosome protein content, shows that most r-proteins turnover in unison in vivo, identifies a novel set of potential plant translatome components, and how protein turnover can help identify r-proteins involved in ribosome biogenesis or regulation in plants.
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27
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Mutational Analysis of the Nsa2 N-Terminus Reveals Its Essential Role in Ribosomal 60S Subunit Assembly. Int J Mol Sci 2020; 21:ijms21239108. [PMID: 33266193 PMCID: PMC7730687 DOI: 10.3390/ijms21239108] [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] [Received: 11/10/2020] [Revised: 11/23/2020] [Accepted: 11/25/2020] [Indexed: 11/23/2022] Open
Abstract
The ribosome assembly factor Nsa2 is part of the Rea1-Rsa4-Nsa2 interconnected relay on nuclear pre-60S particles that is essential for 60S ribosome biogenesis. Cryo-EM structures depict Nsa2 docked via its C-terminal β-barrel domain to nuclear pre-60S particles, whereas the extended N-terminus, consisting of three α-helical segments, meanders between various 25S rRNA helices with the extreme N-terminus in close vicinity to the Nog1 GTPase center. Here, we tested whether this unappreciated proximity between Nsa2 and Nog1 is of functional importance. Our findings demonstrate that a conservative mutation, Nsa2 Q3N, abolished cell growth and impaired 60S biogenesis. Subsequent genetic and biochemical analyses verified that the Nsa2 N-terminus is required to target Nsa2 to early pre-60S particles. However, overexpression of the Nsa2 N-terminus abolished cytoplasmic recycling of the Nog1 GTPase, and both Nog1 and the Nsa2-N (1-58) construct, but not the respective Nsa2-N (1-58) Q3N mutant, were found arrested on late cytoplasmic pre-60S particles. These findings point to specific roles of the different Nsa2 domains for 60S ribosome biogenesis.
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28
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Micic J, Li Y, Wu S, Wilson D, Tutuncuoglu B, Gao N, Woolford JL. Coupling of 5S RNP rotation with maturation of functional centers during large ribosomal subunit assembly. Nat Commun 2020; 11:3751. [PMID: 32719344 PMCID: PMC7385084 DOI: 10.1038/s41467-020-17534-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 06/29/2020] [Indexed: 12/29/2022] Open
Abstract
The protein composition and structure of assembling 60S ribosomal subunits undergo numerous changes as pre-ribosomes transition from the nucleolus to the nucleoplasm. This includes stable anchoring of the Rpf2 subcomplex containing 5S rRNA, rpL5, rpL11, Rpf2 and Rrs1, which initially docks onto the flexible domain V of rRNA at earlier stages of assembly. In this work, we tested the function of the C-terminal domain (CTD) of Rpf2 during these anchoring steps, by truncating this extension and assaying effects on middle stages of subunit maturation. The rpf2Δ255-344 mutation affects proper folding of rRNA helices H68-70 during anchoring of the Rpf2 subcomplex. In addition, several assembly factors (AFs) are absent from pre-ribosomes or in altered conformations. Consequently, major remodeling events fail to occur: rotation of the 5S RNP, maturation of the peptidyl transferase center (PTC) and the nascent polypeptide exit tunnel (NPET), and export of assembling subunits to the cytoplasm. As assembling 60S subunits transit from the nucleolus to the nucleoplasm, they undergo significant changes in protein composition and structure. Here, the authors provide a structural view of interconnected events during the middle steps of assembly that include the maturation of the central protuberance, the peptidyltransferase center and the nascent polypeptide exit tunnel.
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Affiliation(s)
- Jelena Micic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Yu Li
- State Key Laboratory of Membrane Biology, School of Life Science, Tsinghua University, Beijing, China.,Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Beijing, China
| | - Shan Wu
- State Key Laboratory of Membrane Biology, School of Life Science, Tsinghua University, Beijing, China.,State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, School of Life Sciences, Hubei University, Wuhan, China
| | - Daniel Wilson
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Beril Tutuncuoglu
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA.
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29
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Long-range intramolecular allostery and regulation in the dynein-like AAA protein Mdn1. Proc Natl Acad Sci U S A 2020; 117:18459-18469. [PMID: 32694211 DOI: 10.1073/pnas.2002792117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mdn1 is an essential mechanoenzyme that uses the energy from ATP hydrolysis to physically reshape and remodel, and thus mature, the 60S subunit of the ribosome. This massive (>500 kDa) protein has an N-terminal AAA (ATPase associated with diverse cellular activities) ring, which, like dynein, has six ATPase sites. The AAA ring is followed by large (>2,000 aa) linking domains that include an ∼500-aa disordered (D/E-rich) region, and a C-terminal substrate-binding MIDAS domain. Recent models suggest that intramolecular docking of the MIDAS domain onto the AAA ring is required for Mdn1 to transmit force to its ribosomal substrates, but it is not currently understood what role the linking domains play, or why tethering the MIDAS domain to the AAA ring is required for protein function. Here, we use chemical probes, single-particle electron microscopy, and native mass spectrometry to study the AAA and MIDAS domains separately or in combination. We find that Mdn1 lacking the D/E-rich and MIDAS domains retains ATP and chemical probe binding activities. Free MIDAS domain can bind to the AAA ring of this construct in a stereo-specific bimolecular interaction, and, interestingly, this binding reduces ATPase activity. Whereas intramolecular MIDAS docking appears to require a treatment with a chemical inhibitor or preribosome binding, bimolecular MIDAS docking does not. Hence, tethering the MIDAS domain to the AAA ring serves to prevent, rather than promote, MIDAS docking in the absence of inducing signals.
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30
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Kater L, Mitterer V, Thoms M, Cheng J, Berninghausen O, Beckmann R, Hurt E. Construction of the Central Protuberance and L1 Stalk during 60S Subunit Biogenesis. Mol Cell 2020; 79:615-628.e5. [PMID: 32668200 DOI: 10.1016/j.molcel.2020.06.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 05/13/2020] [Accepted: 06/18/2020] [Indexed: 12/15/2022]
Abstract
Ribosome assembly is driven by numerous assembly factors, including the Rix1 complex and the AAA ATPase Rea1. These two assembly factors catalyze 60S maturation at two distinct states, triggering poorly understood large-scale structural transitions that we analyzed by cryo-electron microscopy. Two nuclear pre-60S intermediates were discovered that represent previously unknown states after Rea1-mediated removal of the Ytm1-Erb1 complex and reveal how the L1 stalk develops from a pre-mature nucleolar to a mature-like nucleoplasmic state. A later pre-60S intermediate shows how the central protuberance arises, assisted by the nearby Rix1-Rea1 machinery, which was solved in its pre-ribosomal context to molecular resolution. This revealed a Rix12-Ipi32 tetramer anchored to the pre-60S via Ipi1, strategically positioned to monitor this decisive remodeling. These results are consistent with a general underlying principle that temporarily stabilized immature RNA domains are successively remodeled by assembly factors, thereby ensuring failsafe assembly progression.
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Affiliation(s)
- Lukas Kater
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Valentin Mitterer
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Matthias Thoms
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany; Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Jingdong Cheng
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Otto Berninghausen
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Roland Beckmann
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany.
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany.
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31
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From Snapshots to Flipbook-Resolving the Dynamics of Ribosome Biogenesis with Chemical Probes. Int J Mol Sci 2020; 21:ijms21082998. [PMID: 32340379 PMCID: PMC7215809 DOI: 10.3390/ijms21082998] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/17/2020] [Accepted: 04/22/2020] [Indexed: 12/27/2022] Open
Abstract
The synthesis of ribosomes is one of the central and most resource demanding processes in each living cell. As ribosome biogenesis is tightly linked with the regulation of the cell cycle, perturbation of ribosome formation can trigger severe diseases, including cancer. Eukaryotic ribosome biogenesis starts in the nucleolus with pre-rRNA transcription and the initial assembly steps, continues in the nucleoplasm and is finished in the cytoplasm. From start to end, this process is highly dynamic and finished within few minutes. Despite the tremendous progress made during the last decade, the coordination of the individual maturation steps is hard to unravel by a conventional methodology. In recent years small molecular compounds were identified that specifically block either rDNA transcription or distinct steps within the maturation pathway. As these inhibitors diffuse into the cell rapidly and block their target proteins within seconds, they represent excellent tools to investigate ribosome biogenesis. Here we review how the inhibitors affect ribosome biogenesis and discuss how these effects can be interpreted by taking the complex self-regulatory mechanisms of the pathway into account. With this we want to highlight the potential of low molecular weight inhibitors to approach the dynamic nature of the ribosome biogenesis pathway.
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32
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Braun CM, Hackert P, Schmid CE, Bohnsack MT, Bohnsack KE, Perez-Fernandez J. Pol5 is required for recycling of small subunit biogenesis factors and for formation of the peptide exit tunnel of the large ribosomal subunit. Nucleic Acids Res 2020; 48:405-420. [PMID: 31745560 PMCID: PMC7145529 DOI: 10.1093/nar/gkz1079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 10/29/2019] [Accepted: 11/04/2019] [Indexed: 01/24/2023] Open
Abstract
More than 200 assembly factors (AFs) are required for the production of ribosomes in yeast. The stepwise association and dissociation of these AFs with the pre-ribosomal subunits occurs in a hierarchical manner to ensure correct maturation of the pre-rRNAs and assembly of the ribosomal proteins. Although decades of research have provided a wealth of insights into the functions of many AFs, others remain poorly characterized. Pol5 was initially classified with B-type DNA polymerases, however, several lines of evidence indicate the involvement of this protein in ribosome assembly. Here, we show that depletion of Pol5 affects the processing of pre-rRNAs destined for the both the large and small subunits. Furthermore, we identify binding sites for Pol5 in the 5' external transcribed spacer and within domain III of the 25S rRNA sequence. Consistent with this, we reveal that Pol5 is required for recruitment of ribosomal proteins that form the polypeptide exit tunnel in the LSU and that depletion of Pol5 impairs the release of 5' ETS fragments from early pre-40S particles. The dual functions of Pol5 in 60S assembly and recycling of pre-40S AFs suggest that this factor could contribute to ensuring the stoichiometric production of ribosomal subunits.
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Affiliation(s)
- Christina M Braun
- Department of Biochemistry III, University of Regensburg, Universitätstrasse 31, 93053 Regensburg, Germany
| | - Philipp Hackert
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Catharina E Schmid
- Department of Biochemistry III, University of Regensburg, Universitätstrasse 31, 93053 Regensburg, Germany
| | - Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.,Göttingen Center for Molecular Biosciences, Georg-August University, Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Jorge Perez-Fernandez
- Department of Biochemistry III, University of Regensburg, Universitätstrasse 31, 93053 Regensburg, Germany
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33
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Abstract
In the past 25 years, genetic and biochemical analyses of ribosome assembly in yeast have identified most of the factors that participate in this complex pathway and have generated models for the mechanisms driving the assembly. More recently, the publication of numerous cryo-electron microscopy structures of yeast ribosome assembly intermediates has provided near-atomic resolution snapshots of ribosome precursor particles. Satisfyingly, these structural data support the genetic and biochemical models and provide additional mechanistic insight into ribosome assembly. In this Review, we discuss the mechanisms of assembly of the yeast small ribosomal subunit and large ribosomal subunit in the nucleolus, nucleus and cytoplasm. Particular emphasis is placed on concepts such as the mechanisms of RNA compaction, the functions of molecular switches and molecular mimicry, the irreversibility of assembly checkpoints and the roles of structural and functional proofreading of pre-ribosomal particles.
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34
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Shaping the Nascent Ribosome: AAA-ATPases in Eukaryotic Ribosome Biogenesis. Biomolecules 2019; 9:biom9110715. [PMID: 31703473 PMCID: PMC6920918 DOI: 10.3390/biom9110715] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/04/2019] [Accepted: 11/05/2019] [Indexed: 02/08/2023] Open
Abstract
AAA-ATPases are molecular engines evolutionarily optimized for the remodeling of proteins and macromolecular assemblies. Three AAA-ATPases are currently known to be involved in the remodeling of the eukaryotic ribosome, a megadalton range ribonucleoprotein complex responsible for the translation of mRNAs into proteins. The correct assembly of the ribosome is performed by a plethora of additional and transiently acting pre-ribosome maturation factors that act in a timely and spatially orchestrated manner. Minimal disorder of the assembly cascade prohibits the formation of functional ribosomes and results in defects in proliferation and growth. Rix7, Rea1, and Drg1, which are well conserved across eukaryotes, are involved in different maturation steps of pre-60S ribosomal particles. These AAA-ATPases provide energy for the efficient removal of specific assembly factors from pre-60S particles after they have fulfilled their function in the maturation cascade. Recent structural and functional insights have provided the first glimpse into the molecular mechanism of target recognition and remodeling by Rix7, Rea1, and Drg1. Here we summarize current knowledge on the AAA-ATPases involved in eukaryotic ribosome biogenesis. We highlight the latest insights into their mechanism of mechano-chemical complex remodeling driven by advanced cryo-EM structures and the use of highly specific AAA inhibitors.
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35
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Weisser M, Ban N. Extensions, Extra Factors, and Extreme Complexity: Ribosomal Structures Provide Insights into Eukaryotic Translation. Cold Spring Harb Perspect Biol 2019; 11:11/9/a032367. [PMID: 31481454 DOI: 10.1101/cshperspect.a032367] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although the basic aspects of protein synthesis are preserved in all kingdoms of life, there are many important structural and functional differences between bacterial and the more complex eukaryotic ribosomes. High-resolution cryo-electron microscopy (cryo-EM) and X-ray crystallography structures of eukaryotic ribosomes have revealed the complex architectures of eukaryotic ribosomes and species-specific variations in protein and ribosomal RNA (rRNA) extensions. They also enabled structural studies of a range of eukaryotic ribosomal complexes involved in translation initiation, elongation, and termination, revealing unique mechanistic features of the eukaryotic translation process, especially with respect to the identification and recognition of translation start and stop codons on messenger RNAs (mRNAs). Most recently, structural biology has provided insights into the eukaryotic ribosomal biogenesis pathway by visualizing several of its complex intermediates. This review highlights the past decade's structural work on eukaryotic ribosomes and its implications on our understanding of eukaryotic translation.
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Affiliation(s)
- Melanie Weisser
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Nenad Ban
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, 8093 Zürich, Switzerland
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36
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Ahmed YL, Thoms M, Mitterer V, Sinning I, Hurt E. Crystal structures of Rea1-MIDAS bound to its ribosome assembly factor ligands resembling integrin-ligand-type complexes. Nat Commun 2019; 10:3050. [PMID: 31296859 PMCID: PMC6624252 DOI: 10.1038/s41467-019-10922-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/10/2019] [Indexed: 01/08/2023] Open
Abstract
The Rea1 AAA+-ATPase dislodges assembly factors from pre-60S ribosomes upon ATP hydrolysis, thereby driving ribosome biogenesis. Here, we present crystal structures of Rea1-MIDAS, the conserved domain at the tip of the flexible Rea1 tail, alone and in complex with its substrate ligands, the UBL domains of Rsa4 or Ytm1. These complexes have structural similarity to integrin α-subunit domains when bound to extracellular matrix ligands, which for integrin biology is a key determinant for force-bearing cell-cell adhesion. However, the presence of additional motifs equips Rea1-MIDAS for its tasks in ribosome maturation. One loop insert cofunctions as an NLS and to activate the mechanochemical Rea1 cycle, whereas an additional β-hairpin provides an anchor to hold the ligand UBL domains in place. Our data show the versatility of the MIDAS fold for mechanical force transmission in processes as varied as integrin-mediated cell adhesion and mechanochemical removal of assembly factors from pre-ribosomes.
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Affiliation(s)
| | - Matthias Thoms
- Heidelberg University Biochemistry Center, D-69120, Heidelberg, Germany.,Gene Center, University of Munich, D-81377, Munich, Germany
| | - Valentin Mitterer
- Heidelberg University Biochemistry Center, D-69120, Heidelberg, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center, D-69120, Heidelberg, Germany.
| | - Ed Hurt
- Heidelberg University Biochemistry Center, D-69120, Heidelberg, Germany.
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37
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Awad D, Prattes M, Kofler L, Rössler I, Loibl M, Pertl M, Zisser G, Wolinski H, Pertschy B, Bergler H. Inhibiting eukaryotic ribosome biogenesis. BMC Biol 2019; 17:46. [PMID: 31182083 PMCID: PMC6558755 DOI: 10.1186/s12915-019-0664-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/14/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Ribosome biogenesis is a central process in every growing cell. In eukaryotes, it requires more than 250 non-ribosomal assembly factors, most of which are essential. Despite this large repertoire of potential targets, only very few chemical inhibitors of ribosome biogenesis are known so far. Such inhibitors are valuable tools to study this highly dynamic process and elucidate mechanistic details of individual maturation steps. Moreover, ribosome biogenesis is of particular importance for fast proliferating cells, suggesting its inhibition could be a valid strategy for treatment of tumors or infections. RESULTS We systematically screened ~ 1000 substances for inhibitory effects on ribosome biogenesis using a microscopy-based screen scoring ribosomal subunit export defects. We identified 128 compounds inhibiting maturation of either the small or the large ribosomal subunit or both. Northern blot analysis demonstrates that these inhibitors cause a broad spectrum of different rRNA processing defects. CONCLUSIONS Our findings show that the individual inhibitors affect a wide range of different maturation steps within the ribosome biogenesis pathway. Our results provide for the first time a comprehensive set of inhibitors to study ribosome biogenesis by chemical inhibition of individual maturation steps and establish the process as promising druggable pathway for chemical intervention.
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Affiliation(s)
- Dominik Awad
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
- Present address: Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Michael Prattes
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Lisa Kofler
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Ingrid Rössler
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Mathias Loibl
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Melanie Pertl
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Gertrude Zisser
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Heimo Wolinski
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria
| | - Brigitte Pertschy
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria.
| | - Helmut Bergler
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/EG, A-8010, Graz, Austria.
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38
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Li PC, Li K, Wang J, Zhao CZ, Zhao SZ, Hou L, Xia H, Ma CL, Wang XJ. The AAA-ATPase MIDASIN 1 Functions in Ribosome Biogenesis and Is Essential for Embryo and Root Development. PLANT PHYSIOLOGY 2019; 180:289-304. [PMID: 30755475 PMCID: PMC6501072 DOI: 10.1104/pp.18.01225] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 01/30/2019] [Indexed: 05/04/2023]
Abstract
Ribosome biogenesis is an orchestrated process that relies on many assembly factors. The AAA-ATPase Midasin 1 (Mdn1) functions as a ribosome assembly factor in yeast (Saccharomyces cerevisiae), but the roles of MDN1 in Arabidopsis (Arabidopsis thaliana) are poorly understood. Here, we showed that the Arabidopsis null mutant of MDN1 is embryo-lethal. Using the weak mutant mdn1-1, which maintains viability, we found that MDN1 is critical for the regular pattern of auxin maxima in the globular embryo and functions in root meristem maintenance. By detecting the subcellular distribution of ribosome proteins, we noted that mdn1-1 impairs nuclear export of the pre-60S ribosomal particle. The processing of ribosomal precusor RNAs, including 35S, 27SB, and 20S, is also affected in this mutant. MDN1 physically interacts with PESCADILLO2 (PES2), an essential assembly factor of the 60S ribosome, and the observed mislocalization of PES2 in mdn1-1 further implied that MDN1 plays an indispensable role in 60S ribosome biogenesis. Therefore, the observed hypersensitivity of mdn1-1 to a eukaryotic translation inhibitor and high-sugar conditions might be associated with the defect in ribosome biogenesis. Overall, this work establishes a role of Arabidopsis MDN1 in ribosome biogenesis, which agrees with its roles in embryogenesis and root development.
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Affiliation(s)
- Peng-Cheng Li
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Ke Li
- College of Life Science, Shandong University, Qingdao 266237, PR China
| | - Juan Wang
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Chuan-Zhi Zhao
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Shu-Zhen Zhao
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Lei Hou
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Han Xia
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
| | - Chang-Le Ma
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Xing-Jun Wang
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan 250100, PR China
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39
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Cryo-EM structure of the essential ribosome assembly AAA-ATPase Rix7. Nat Commun 2019; 10:513. [PMID: 30705282 PMCID: PMC6355894 DOI: 10.1038/s41467-019-08373-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/28/2018] [Indexed: 01/24/2023] Open
Abstract
Rix7 is an essential type II AAA-ATPase required for the formation of the large ribosomal subunit. Rix7 has been proposed to utilize the power of ATP hydrolysis to drive the removal of assembly factors from pre-60S particles, but the mechanism of release is unknown. Rix7's mammalian homolog, NVL2 has been linked to cancer and mental illness disorders, highlighting the need to understand the molecular mechanisms of this essential machine. Here we report the cryo-EM reconstruction of the tandem AAA domains of Rix7 which form an asymmetric stacked homohexameric ring. We trapped Rix7 with a polypeptide in the central channel, revealing Rix7's role as a molecular unfoldase. The structure establishes that type II AAA-ATPases lacking the aromatic-hydrophobic motif within the first AAA domain can engage a substrate throughout the entire central channel. The structure also reveals that Rix7 contains unique post-α7 insertions within both AAA domains important for Rix7 function.
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40
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Abstract
Ribosomes, which synthesize the proteins of a cell, comprise ribosomal RNA and ribosomal proteins, which coassemble hierarchically during a process termed ribosome biogenesis. Historically, biochemical and molecular biology approaches have revealed how preribosomal particles form and mature in consecutive steps, starting in the nucleolus and terminating after nuclear export into the cytoplasm. However, only recently, due to the revolution in cryo-electron microscopy, could pseudoatomic structures of different preribosomal particles be obtained. Together with in vitro maturation assays, these findings shed light on how nascent ribosomes progress stepwise along a dynamic biogenesis pathway. Preribosomes assemble gradually, chaperoned by a myriad of assembly factors and small nucleolar RNAs, before they reach maturity and enter translation. This information will lead to a better understanding of how ribosome synthesis is linked to other cellular pathways in humans and how it can cause diseases, including cancer, if disturbed.
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Affiliation(s)
- Jochen Baßler
- Biochemistry Center, University of Heidelberg, 69120 Heidelberg, Germany; ,
| | - Ed Hurt
- Biochemistry Center, University of Heidelberg, 69120 Heidelberg, Germany; ,
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41
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RNA helicases mediate structural transitions and compositional changes in pre-ribosomal complexes. Nat Commun 2018; 9:5383. [PMID: 30568249 PMCID: PMC6300602 DOI: 10.1038/s41467-018-07783-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 11/28/2018] [Indexed: 01/31/2023] Open
Abstract
Production of eukaryotic ribosomal subunits is a highly dynamic process; pre-ribosomes undergo numerous structural rearrangements that establish the architecture present in mature complexes and serve as key checkpoints, ensuring the fidelity of ribosome assembly. Using in vivo crosslinking, we here identify the pre-ribosomal binding sites of three RNA helicases. Our data support roles for Has1 in triggering release of the U14 snoRNP, a critical event during early 40S maturation, and in driving assembly of domain I of pre-60S complexes. Binding of Mak5 to domain II of pre-60S complexes promotes recruitment of the ribosomal protein Rpl10, which is necessary for subunit joining and ribosome function. Spb4 binds to a molecular hinge at the base of ES27 facilitating binding of the export factor Arx1, thereby promoting pre-60S export competence. Our data provide important insights into the driving forces behind key structural remodelling events during ribosomal subunit assembly.
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42
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Sosnowski P, Urnavicius L, Boland A, Fagiewicz R, Busselez J, Papai G, Schmidt H. The CryoEM structure of the Saccharomyces cerevisiae ribosome maturation factor Rea1. eLife 2018; 7:39163. [PMID: 30460895 PMCID: PMC6286127 DOI: 10.7554/elife.39163] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 11/08/2018] [Indexed: 11/29/2022] Open
Abstract
The biogenesis of 60S ribosomal subunits is initiated in the nucleus where rRNAs and proteins form pre-60S particles. These pre-60S particles mature by transiently interacting with various assembly factors. The ~5000 amino-acid AAA+ ATPase Rea1 (or Midasin) generates force to mechanically remove assembly factors from pre-60S particles, which promotes their export to the cytosol. Here we present three Rea1 cryoEM structures. We visualise the Rea1 engine, a hexameric ring of AAA+ domains, and identify an α-helical bundle of AAA2 as a major ATPase activity regulator. The α-helical bundle interferes with nucleotide-induced conformational changes that create a docking site for the substrate binding MIDAS domain on the AAA +ring. Furthermore, we reveal the architecture of the Rea1 linker, which is involved in force generation and extends from the AAA+ ring. The data presented here provide insights into the mechanism of one of the most complex ribosome maturation factors.
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Affiliation(s)
- Piotr Sosnowski
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Linas Urnavicius
- Division of Structural Studies, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Andreas Boland
- Division of Structural Studies, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Robert Fagiewicz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Johan Busselez
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Gabor Papai
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Helgo Schmidt
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
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43
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Chen Z, Suzuki H, Kobayashi Y, Wang AC, DiMaio F, Kawashima SA, Walz T, Kapoor TM. Structural Insights into Mdn1, an Essential AAA Protein Required for Ribosome Biogenesis. Cell 2018; 175:822-834.e18. [PMID: 30318141 DOI: 10.1016/j.cell.2018.09.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 07/23/2018] [Accepted: 09/10/2018] [Indexed: 12/20/2022]
Abstract
Mdn1 is an essential AAA (ATPase associated with various activities) protein that removes assembly factors from distinct precursors of the ribosomal 60S subunit. However, Mdn1's large size (∼5,000 amino acid [aa]) and its limited homology to other well-studied proteins have restricted our understanding of its remodeling function. Here, we present structures for S. pombe Mdn1 in the presence of AMPPNP at up to ∼4 Å or ATP plus Rbin-1, a chemical inhibitor, at ∼8 Å resolution. These data reveal that Mdn1's MIDAS domain is tethered to its ring-shaped AAA domain through an ∼20 nm long structured linker and a flexible ∼500 aa Asp/Glu-rich motif. We find that the MIDAS domain, which also binds other ribosome-assembly factors, docks onto the AAA ring in a nucleotide state-specific manner. Together, our findings reveal how conformational changes in the AAA ring can be directly transmitted to the MIDAS domain and thereby drive the targeted release of assembly factors from ribosomal 60S-subunit precursors.
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Affiliation(s)
- Zhen Chen
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Hiroshi Suzuki
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA
| | - Yuki Kobayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 1130033, Japan
| | - Ashley C Wang
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Shigehiro A Kawashima
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 1130033, Japan
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA.
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA.
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44
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Thoms M, Mitterer V, Kater L, Falquet L, Beckmann R, Kressler D, Hurt E. Suppressor mutations in Rpf2-Rrs1 or Rpl5 bypass the Cgr1 function for pre-ribosomal 5S RNP-rotation. Nat Commun 2018; 9:4094. [PMID: 30291245 PMCID: PMC6173701 DOI: 10.1038/s41467-018-06660-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 09/17/2018] [Indexed: 12/03/2022] Open
Abstract
During eukaryotic 60S biogenesis, the 5S RNP requires a large rotational movement to achieve its mature position. Cryo-EM of the Rix1-Rea1 pre-60S particle has revealed the post-rotation stage, in which a gently undulating α-helix corresponding to Cgr1 becomes wedged between Rsa4 and the relocated 5S RNP, but the purpose of this insertion was unknown. Here, we show that cgr1 deletion in yeast causes a slow-growth phenotype and reversion of the pre-60S particle to the pre-rotation stage. However, spontaneous extragenic suppressors could be isolated, which restore growth and pre-60S biogenesis in the absence of Cgr1. Whole-genome sequencing reveals that the suppressor mutations map in the Rpf2–Rrs1 module and Rpl5, which together stabilize the unrotated stage of the 5S RNP. Thus, mutations in factors stabilizing the pre-rotation stage facilitate 5S RNP relocation upon deletion of Cgr1, but Cgr1 itself could stabilize the post-rotation stage. During biogenesis of the eukaryotic 60S ribosome, a large rotational movement of the 5S RNP is required to achieve its mature position. By analyzing extragenic suppressors of crg1—a key factor required for rotation—the authors provide mechanistic insight into a key step of ribosome biogenesis.
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Affiliation(s)
- Matthias Thoms
- Biochemistry Centre, University of Heidelberg, Heidelberg, 69120, Germany.
| | - Valentin Mitterer
- Biochemistry Centre, University of Heidelberg, Heidelberg, 69120, Germany
| | - Lukas Kater
- Gene Center, University of Munich, Munich, 81377, Germany
| | - Laurent Falquet
- University of Fribourg and Swiss Institute of Bioinformatics, Fribourg, 1700, Switzerland
| | | | - Dieter Kressler
- University of Fribourg and Swiss Institute of Bioinformatics, Fribourg, 1700, Switzerland
| | - Ed Hurt
- Biochemistry Centre, University of Heidelberg, Heidelberg, 69120, Germany.
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45
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Biedka S, Micic J, Wilson D, Brown H, Diorio-Toth L, Woolford JL. Hierarchical recruitment of ribosomal proteins and assembly factors remodels nucleolar pre-60S ribosomes. J Cell Biol 2018; 217:2503-2518. [PMID: 29691304 PMCID: PMC6028539 DOI: 10.1083/jcb.201711037] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/20/2018] [Accepted: 03/29/2018] [Indexed: 01/24/2023] Open
Abstract
Ribosome biogenesis involves numerous pre-rRNA processing events to remove internal and external transcribed spacer sequences, ultimately yielding three mature rRNAs. Biedka et al. show that ribosomal proteins and assembly factors remodel several neighborhoods, including two 60S ribosomal subunit functional centers, during removal of the ITS2 spacer RNA. Ribosome biogenesis involves numerous preribosomal RNA (pre-rRNA) processing events to remove internal and external transcribed spacer sequences, ultimately yielding three mature rRNAs. Removal of the internal transcribed spacer 2 spacer RNA is the final step in large subunit pre-rRNA processing and begins with endonucleolytic cleavage at the C2 site of 27SB pre-rRNA. C2 cleavage requires the hierarchical recruitment of 11 ribosomal proteins and 14 ribosome assembly factors. However, the function of these proteins in C2 cleavage remained unclear. In this study, we have performed a detailed analysis of the effects of depleting proteins required for C2 cleavage and interpreted these results using cryo–electron microscopy structures of assembling 60S subunits. This work revealed that these proteins are required for remodeling of several neighborhoods, including two major functional centers of the 60S subunit, suggesting that these remodeling events form a checkpoint leading to C2 cleavage. Interestingly, when C2 cleavage is directly blocked by depleting or inactivating the C2 endonuclease, assembly progresses through all other subsequent steps.
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Affiliation(s)
- Stephanie Biedka
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
| | - Jelena Micic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
| | - Daniel Wilson
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
| | - Hailey Brown
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
| | - Luke Diorio-Toth
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
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46
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Zhou D, Zhu X, Zheng S, Tan D, Dong MQ, Ye K. Cryo-EM structure of an early precursor of large ribosomal subunit reveals a half-assembled intermediate. Protein Cell 2018; 10:120-130. [PMID: 29557065 PMCID: PMC6340896 DOI: 10.1007/s13238-018-0526-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/04/2018] [Indexed: 11/25/2022] Open
Abstract
Assembly of eukaryotic ribosome is a complicated and dynamic process that involves a series of intermediates. It is unknown how the highly intertwined structure of 60S large ribosomal subunits is established. Here, we report the structure of an early nucleolar pre-60S ribosome determined by cryo-electron microscopy at 3.7 Å resolution, revealing a half-assembled subunit. Domains I, II and VI of 25S/5.8S rRNA pack tightly into a native-like substructure, but domains III, IV and V are not assembled. The structure contains 12 assembly factors and 19 ribosomal proteins, many of which are required for early processing of large subunit rRNA. The Brx1-Ebp2 complex would interfere with the assembly of domains IV and V. Rpf1, Mak16, Nsa1 and Rrp1 form a cluster that consolidates the joining of domains I and II. Our structure reveals a key intermediate on the path to establishing the global architecture of 60S subunits.
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Affiliation(s)
- Dejian Zhou
- Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, 100730, China.,Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, 100101, China.,National Institute of Biological Sciences, Beijing, 102206, China
| | - Xing Zhu
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, 100101, China
| | - Sanduo Zheng
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Dan Tan
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, 102206, China
| | - Keqiong Ye
- Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, 100730, China. .,Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, 100101, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
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47
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Sanghai ZA, Miller L, Molloy KR, Barandun J, Hunziker M, Chaker-Margot M, Wang J, Chait BT, Klinge S. Modular assembly of the nucleolar pre-60S ribosomal subunit. Nature 2018; 556:126-129. [PMID: 29512650 DOI: 10.1038/nature26156] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/23/2018] [Indexed: 12/13/2022]
Abstract
Early co-transcriptional events during eukaryotic ribosome assembly result in the formation of precursors of the small (40S) and large (60S) ribosomal subunits. A multitude of transient assembly factors regulate and chaperone the systematic folding of pre-ribosomal RNA subdomains. However, owing to a lack of structural information, the role of these factors during early nucleolar 60S assembly is not fully understood. Here we report cryo-electron microscopy (cryo-EM) reconstructions of the nucleolar pre-60S ribosomal subunit in different conformational states at resolutions of up to 3.4 Å. These reconstructions reveal how steric hindrance and molecular mimicry are used to prevent both premature folding states and binding of later factors. This is accomplished by the concerted activity of 21 ribosome assembly factors that stabilize and remodel pre-ribosomal RNA and ribosomal proteins. Among these factors, three Brix-domain proteins and their binding partners form a ring-like structure at ribosomal RNA (rRNA) domain boundaries to support the architecture of the maturing particle. The existence of mutually exclusive conformations of these pre-60S particles suggests that the formation of the polypeptide exit tunnel is achieved through different folding pathways during subsequent stages of ribosome assembly. These structures rationalize previous genetic and biochemical data and highlight the mechanisms that drive eukaryotic ribosome assembly in a unidirectional manner.
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Affiliation(s)
- Zahra Assur Sanghai
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Linamarie Miller
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA.,Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, New York, New York 10065, USA
| | - Kelly R Molloy
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Jonas Barandun
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Mirjam Hunziker
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Malik Chaker-Margot
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA.,Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, New York, New York 10065, USA
| | - Junjie Wang
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Sebastian Klinge
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
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48
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Rao L, Hülsemann M, Gennerich A. Combining Structure-Function and Single-Molecule Studies on Cytoplasmic Dynein. Methods Mol Biol 2018; 1665:53-89. [PMID: 28940064 PMCID: PMC5639168 DOI: 10.1007/978-1-4939-7271-5_4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cytoplasmic dynein is the largest and most intricate cytoskeletal motor protein. It is responsible for a vast array of biological functions, ranging from the transport of organelles and mRNAs to the movement of nuclei during neuronal migration and the formation and positioning of the mitotic spindle during cell division. Despite its megadalton size and its complex design, recent success with the recombinant expression of the dynein heavy chain has advanced our understanding of dynein's molecular mechanism through the combination of structure-function and single-molecule studies. Single-molecule fluorescence assays have provided detailed insights into how dynein advances along its microtubule track in the absence of load, while optical tweezers have yielded insights into the force generation and stalling behavior of dynein. Here, using the S. cerevisiae expression system, we provide improved protocols for the generation of dynein mutants and for the expression and purification of the mutated and/or tagged proteins. To facilitate single-molecule fluorescence and optical trapping assays, we further describe updated, easy-to-use protocols for attaching microtubules to coverslip surfaces. The presented protocols together with the recently solved crystal structures of the dynein motor domain will further simplify and accelerate hypothesis-driven mutagenesis and structure-function studies on dynein.
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Affiliation(s)
- Lu Rao
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Jack and Pearl Resnick Campus, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Maren Hülsemann
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Jack and Pearl Resnick Campus, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Arne Gennerich
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Jack and Pearl Resnick Campus, 1300 Morris Park Avenue, Bronx, NY, 10461, USA.
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Kater L, Thoms M, Barrio-Garcia C, Cheng J, Ismail S, Ahmed YL, Bange G, Kressler D, Berninghausen O, Sinning I, Hurt E, Beckmann R. Visualizing the Assembly Pathway of Nucleolar Pre-60S Ribosomes. Cell 2017; 171:1599-1610.e14. [PMID: 29245012 PMCID: PMC5745149 DOI: 10.1016/j.cell.2017.11.039] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 10/13/2017] [Accepted: 11/20/2017] [Indexed: 12/12/2022]
Abstract
Eukaryotic 60S ribosomal subunits are comprised of three rRNAs and ∼50 ribosomal proteins. The initial steps of their formation take place in the nucleolus, but, owing to a lack of structural information, this process is poorly understood. Using cryo-EM, we solved structures of early 60S biogenesis intermediates at 3.3 Å to 4.5 Å resolution, thereby providing insights into their sequential folding and assembly pathway. Besides revealing distinct immature rRNA conformations, we map 25 assembly factors in six different assembly states. Notably, the Nsa1-Rrp1-Rpf1-Mak16 module stabilizes the solvent side of the 60S subunit, and the Erb1-Ytm1-Nop7 complex organizes and connects through Erb1's meandering N-terminal extension, eight assembly factors, three ribosomal proteins, and three 25S rRNA domains. Our structural snapshots reveal the order of integration and compaction of the six major 60S domains within early nucleolar 60S particles developing stepwise from the solvent side around the exit tunnel to the central protuberance.
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Affiliation(s)
- Lukas Kater
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Matthias Thoms
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Clara Barrio-Garcia
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Jingdong Cheng
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Sherif Ismail
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | | | - Gert Bange
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Dieter Kressler
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Otto Berninghausen
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany
| | - Irmgard Sinning
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany
| | - Roland Beckmann
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany.
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Fromm L, Falk S, Flemming D, Schuller JM, Thoms M, Conti E, Hurt E. Reconstitution of the complete pathway of ITS2 processing at the pre-ribosome. Nat Commun 2017; 8:1787. [PMID: 29176610 PMCID: PMC5702609 DOI: 10.1038/s41467-017-01786-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 10/12/2017] [Indexed: 01/19/2023] Open
Abstract
Removal of internal transcribed spacer 2 (ITS2) from pre-ribosomal RNA is essential to make functional ribosomes. This complicated processing reaction begins with a single endonucleolytic cleavage followed by exonucleolytic trimming at both new cleavage sites to generate mature 5.8S and 25S rRNA. We reconstituted the 7S→5.8S processing branch within ITS2 using purified exosome and its nuclear cofactors. We find that both Rrp44’s ribonuclease activities are required for initial RNA shortening followed by hand over to the exonuclease Rrp6. During the in vitro reaction, ITS2-associated factors dissociate and the underlying ‘foot’ structure of the pre-60S particle is dismantled. 7S pre-rRNA processing is independent of 5S RNP rotation, but 26S→25S trimming is a precondition for subsequent 7S→5.8S processing. To complete the in vitro assay, we reconstituted the entire cycle of ITS2 removal with a total of 18 purified factors, catalysed by the integrated activities of the two participating RNA-processing machines, the Las1 complex and nuclear exosome. Excision of internal transcribed spacer 2 (ITS2) within eukaryotic pre-ribosomal RNA is essential for ribosome function. Here, the authors reconstitute the entire cycle of ITS2 processing in vitro using purified components, providing insights into the cleavage process and demonstrating that 26S pre-rRNA processing necessarily precedes 7S pre-rRNA processing.
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Affiliation(s)
- Lisa Fromm
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg, D-69120, Germany
| | - Sebastian Falk
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152, Martinsried, Germany
| | - Dirk Flemming
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg, D-69120, Germany
| | - Jan Michael Schuller
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152, Martinsried, Germany
| | - Matthias Thoms
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg, D-69120, Germany
| | - Elena Conti
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152, Martinsried, Germany
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg, D-69120, Germany.
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