1
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Baymukhametov TN, Lyabin DN, Chesnokov YM, Sorokin II, Pechnikova E, Vasiliev A, Afonina Z. Polyribosomes of circular topology are prevalent in mammalian cells. Nucleic Acids Res 2022; 51:908-918. [PMID: 36583341 PMCID: PMC9881139 DOI: 10.1093/nar/gkac1208] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/31/2022] Open
Abstract
Polyribosomes, the groups of ribosomes simultaneously translating a single mRNA molecule, are very common in both, prokaryotic and eukaryotic cells. Even in early EM studies, polyribosomes have been shown to possess various spatial conformations, including a ring-shaped configuration which was considered to be functionally important. However, a recent in situ cryo-ET analysis of predominant regular inter-ribosome contacts did not confirm the abundance of ring-shaped polyribosomes in a cell cytoplasm. To address this discrepancy, here we analyzed the cryo-ET structure of polyribosomes in diluted lysates of HeLa cells. It was shown that the vast majority of the ribosomes were combined into polysomes and were proven to be translationally active. Tomogram analysis revealed that circular polyribosomes are indeed very common in the cytoplasm, but they mostly possess pseudo-regular structures without specific inter-ribosomal contacts. Although the size of polyribosomes varied widely, most circular polysomes were relatively small in size (4-8 ribosomes). Our results confirm the recent data that it is cellular mRNAs with short ORF that most commonly form circular structures providing an enhancement of translation.
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Affiliation(s)
- Timur N Baymukhametov
- Structural biology department, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia
| | - Dmitry N Lyabin
- Institute of Protein Research RAS, Pushchino, Moscow Region 142290, Russia
| | - Yury M Chesnokov
- Probe and Electron Microscopy Resource Center, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia
| | - Ivan I Sorokin
- Institute of Protein Research RAS, Pushchino, Moscow Region 142290, Russia
| | - Evgeniya V Pechnikova
- Probe and Electron Microscopy Resource Center, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia,Electron Microscopy Laboratory, Shubnikov Institute of Crystallography of Federal Scientific Research Centre ‘Crystallography and Photonics’ RAS, Moscow 119333, Russia
| | - Alexander L Vasiliev
- Probe and Electron Microscopy Resource Center, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia,Electron Microscopy Laboratory, Shubnikov Institute of Crystallography of Federal Scientific Research Centre ‘Crystallography and Photonics’ RAS, Moscow 119333, Russia
| | - Zhanna A Afonina
- To whom correspondence should be addressed. Tel: +7 985 7232812; Fax: +7 4967 318435;
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2
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Jiang W, Wagner J, Du W, Plitzko J, Baumeister W, Beck F, Guo Q. A transformation clustering algorithm and its application in polyribosomes structural profiling. Nucleic Acids Res 2022; 50:9001-9011. [PMID: 35811088 PMCID: PMC9458451 DOI: 10.1093/nar/gkac547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/01/2022] [Accepted: 06/10/2022] [Indexed: 12/26/2022] Open
Abstract
Improvements in cryo-electron tomography sample preparation, electron-microscopy instrumentations, and image processing algorithms have advanced the structural analysis of macromolecules in situ. Beyond such analyses of individual macromolecules, the study of their interactions with functionally related neighbors in crowded cellular habitats, i.e. ‘molecular sociology’, is of fundamental importance in biology. Here we present a NEighboring Molecule TOpology Clustering (NEMO-TOC) algorithm. We optimized this algorithm for the detection and profiling of polyribosomes, which play both constitutive and regulatory roles in gene expression. Our results suggest a model where polysomes are formed by connecting multiple nonstochastic blocks, in which translation is likely synchronized.
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Affiliation(s)
- Wenhong Jiang
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University , Beijing 100871, China
| | - Jonathan Wagner
- Department of Structural Molecular Biology, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Wenjing Du
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University , Beijing 100871, China
| | - Juergen Plitzko
- CryoEM Technology, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Structural Molecular Biology, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Florian Beck
- CryoEM Technology, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Qiang Guo
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University , Beijing 100871, China
- Changping Laboratory , Beijing, China
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3
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Klaholz BP. Studying the Structural Organization of Polyribosomes with Alexander S. Spirin. BIOCHEMISTRY (MOSCOW) 2021; 86:1053-1059. [PMID: 34565311 DOI: 10.1134/s0006297921090030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
"Would it be possible to analyze molecular mechanisms and structural organisation of polyribosome assemblies using cryo electron tomography?" - we asked through a longstanding collaboration between my research group and that of Alexander S. Spirin. Indeed, it was: we found that double-row polyribosomes can have both circular and linear arrangements of their mRNA [Afonina, Z. A., et al. (2013) Biochemistry (Moscow)], we figured out how eukaryotic ribosomes assemble on an mRNA to form supramolecular left-handed helices [Myasnikov, A. G., et al. (2014) Nat. Commun.], that the circularization of polyribosomes is poly-A and cap-independent [Afonina, Z. A., et al. (2014) Nucleic Acids Res.], and that intermediary polyribosomes with open structures exist after a transition from a juvenile phase to strongly translating polysomes of medium size [Afonina, Z. A., et al. (2015) Nucleic Acids Res.] until they form densely packed helical structures with reduced activity. Our joint fruitful exchanges, hence, led to major advances in the field, which are reviewed here from a personal and historical perspective in memory of Alexander S. Spirin.
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Affiliation(s)
- Bruno P Klaholz
- Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Illkirch, 67404, France. .,Centre National de la Recherche Scientifique (CNRS) UMR 7104, Illkirch, 67404, France.,Institut National de la Santé et de la Recherche Médicale (INSERM) U964, Illkirch, 67404, France.,Université de Strasbourg, Strasbourg, 67081, France
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4
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Morphological Heterogeneity of the Endoplasmic Reticulum within Neurons and Its Implications in Neurodegeneration. Cells 2021; 10:cells10050970. [PMID: 33919188 PMCID: PMC8143122 DOI: 10.3390/cells10050970] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/13/2021] [Accepted: 04/19/2021] [Indexed: 12/19/2022] Open
Abstract
The endoplasmic reticulum (ER) is a multipurpose organelle comprising dynamic structural subdomains, such as ER sheets and tubules, serving to maintain protein, calcium, and lipid homeostasis. In neurons, the single ER is compartmentalized with a careful segregation of the structural subdomains in somatic and neurite (axodendritic) regions. The distribution and arrangement of these ER subdomains varies between different neuronal types. Mutations in ER membrane shaping proteins and morphological changes in the ER are associated with various neurodegenerative diseases implying significance of ER morphology in maintaining neuronal integrity. Specific neurons, such as the highly arborized dopaminergic neurons, are prone to stress and neurodegeneration. Differences in morphology and functionality of ER between the neurons may account for their varied sensitivity to stress and neurodegenerative changes. In this review, we explore the neuronal ER and discuss its distinct morphological attributes and specific functions. We hypothesize that morphological heterogeneity of the ER in neurons is an important factor that accounts for their selective susceptibility to neurodegeneration.
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5
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Gaba A, Wang H, Fortune T, Qu X. Smart-ORF: a single-molecule method for accessing ribosome dynamics in both upstream and main open reading frames. Nucleic Acids Res 2021; 49:e26. [PMID: 33330921 PMCID: PMC7969011 DOI: 10.1093/nar/gkaa1185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/16/2020] [Accepted: 11/20/2020] [Indexed: 11/15/2022] Open
Abstract
Upstream open reading frame (uORF) translation disrupts scanning 43S flux on mRNA and modulates main open reading frame (mORF) translation efficiency. Current tools, however, have limited access to ribosome dynamics in both upstream and main ORFs of an mRNA. Here, we develop a new two-color in vitro fluorescence assay, Smart-ORF, that monitors individual uORF and mORF translation events in real-time with single-molecule resolution. We demonstrate the utility of Smart-ORF by applying it to uORF-encoded arginine attenuator peptide (AAP)-mediated translational regulation. The method enabled quantification of uORF and mORF initiation efficiencies, 80S dwell time, polysome formation, and the correlation between uORF and mORF translation dynamics. Smart-ORF revealed that AAP-mediated 80S stalling in the uORF stimulates the uORF initiation efficiency and promotes clustering of slower uORF-translating ribosomes. This technology provides a new tool that can reveal previously uncharacterized dynamics of uORF-containing mRNA translation.
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Affiliation(s)
- Anthony Gaba
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Hongyun Wang
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Trinisia Fortune
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Xiaohui Qu
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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6
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Carter SD, Hampton CM, Langlois R, Melero R, Farino ZJ, Calderon MJ, Li W, Wallace CT, Tran NH, Grassucci RA, Siegmund SE, Pemberton J, Morgenstern TJ, Eisenman L, Aguilar JI, Greenberg NL, Levy ES, Yi E, Mitchell WG, Rice WJ, Wigge C, Pilli J, George EW, Aslanoglou D, Courel M, Freyberg RJ, Javitch JA, Wills ZP, Area-Gomez E, Shiva S, Bartolini F, Volchuk A, Murray SA, Aridor M, Fish KN, Walter P, Balla T, Fass D, Wolf SG, Watkins SC, Carazo JM, Jensen GJ, Frank J, Freyberg Z. Ribosome-associated vesicles: A dynamic subcompartment of the endoplasmic reticulum in secretory cells. SCIENCE ADVANCES 2020; 6:eaay9572. [PMID: 32270040 PMCID: PMC7112762 DOI: 10.1126/sciadv.aay9572] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 01/13/2020] [Indexed: 05/21/2023]
Abstract
The endoplasmic reticulum (ER) is a highly dynamic network of membranes. Here, we combine live-cell microscopy with in situ cryo-electron tomography to directly visualize ER dynamics in several secretory cell types including pancreatic β-cells and neurons under near-native conditions. Using these imaging approaches, we identify a novel, mobile form of ER, ribosome-associated vesicles (RAVs), found primarily in the cell periphery, which is conserved across different cell types and species. We show that RAVs exist as distinct, highly dynamic structures separate from the intact ER reticular architecture that interact with mitochondria via direct intermembrane contacts. These findings describe a new ER subcompartment within cells.
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Affiliation(s)
- Stephen D. Carter
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Cheri M. Hampton
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Robert Langlois
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Roberto Melero
- Biocomputing Unit, Centro Nacional de Biotecnología–CSIC, Darwin 3, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Zachary J. Farino
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Michael J. Calderon
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Wen Li
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Callen T. Wallace
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Ngoc Han Tran
- HHMI, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Robert A. Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Stephanie E. Siegmund
- Department of Cellular, Molecular and Biophysical Studies, Columbia University Medical Center, New York, NY 10032, USA
- Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Joshua Pemberton
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Travis J. Morgenstern
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Leanna Eisenman
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jenny I. Aguilar
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Nili L. Greenberg
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Elana S. Levy
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Edward Yi
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - William G. Mitchell
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | | | | | - Jyotsna Pilli
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Emily W. George
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Despoina Aslanoglou
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Maïté Courel
- CNRS-UMR7622, Institut de Biologie Paris-Seine, Université Pierre & Marie Curie, 75252 Paris, France
| | - Robin J. Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jonathan A. Javitch
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Zachary P. Wills
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Estela Area-Gomez
- Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Sruti Shiva
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Francesca Bartolini
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Allen Volchuk
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Sandra A. Murray
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Meir Aridor
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Kenneth N. Fish
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Peter Walter
- HHMI, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Sharon G. Wolf
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Simon C. Watkins
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - José María Carazo
- Biocomputing Unit, Centro Nacional de Biotecnología–CSIC, Darwin 3, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Grant J. Jensen
- HHMI, Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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7
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Gray WT, Govers SK, Xiang Y, Parry BR, Campos M, Kim S, Jacobs-Wagner C. Nucleoid Size Scaling and Intracellular Organization of Translation across Bacteria. Cell 2020; 177:1632-1648.e20. [PMID: 31150626 DOI: 10.1016/j.cell.2019.05.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/01/2019] [Accepted: 05/08/2019] [Indexed: 01/10/2023]
Abstract
The scaling of organelles with cell size is thought to be exclusive to eukaryotes. Here, we demonstrate that similar scaling relationships hold for the bacterial nucleoid. Despite the absence of a nuclear membrane, nucleoid size strongly correlates with cell size, independent of changes in DNA amount and across various nutrient conditions. This correlation is observed in diverse bacteria, revealing a near-constant ratio between nucleoid and cell size for a given species. As in eukaryotes, the nucleocytoplasmic ratio in bacteria varies greatly among species. This spectrum of nucleocytoplasmic ratios is independent of genome size, and instead it appears linked to the average population cell size. Bacteria with different nucleocytoplasmic ratios have a cytoplasm with different biophysical properties, impacting ribosome mobility and localization. Together, our findings identify new organizational principles and biophysical features of bacterial cells, implicating the nucleocytoplasmic ratio and cell size as determinants of the intracellular organization of translation.
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Affiliation(s)
- William T Gray
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Pharmacology, Yale University, New Haven, CT, USA
| | - Sander K Govers
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Yingjie Xiang
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Bradley R Parry
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Manuel Campos
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Sangjin Kim
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Christine Jacobs-Wagner
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT, USA; Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, USA.
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8
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Abstract
The proper regulation of mRNA processing, localization, translation, and degradation occurs on mRNPs. However, the global principles of mRNP organization are poorly understood. We utilize the limited, but existing, information available to present a speculative synthesis of mRNP organization with the following key points. First, mRNPs form a compacted structure due to the inherent folding of RNA. Second, the ribosome is the principal mechanism by which mRNA regions are partially decompacted. Third, mRNPs are 50%-80% protein by weight, consistent with proteins modulating mRNP organization, but also suggesting the majority of mRNA sequences are not directly interacting with RNA-binding proteins. Finally, the ratio of mRNA-binding proteins to mRNAs is higher in the nucleus to allow effective RNA processing and limit the potential for nuclear RNA based aggregation. This synthesis of mRNP understanding provides a model for mRNP biogenesis, structure, and regulation with multiple implications.
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Affiliation(s)
- Anthony Khong
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
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9
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Tahmasebi S, Sonenberg N, Hershey JWB, Mathews MB. Protein Synthesis and Translational Control: A Historical Perspective. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035584. [PMID: 30082466 DOI: 10.1101/cshperspect.a035584] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Protein synthesis and its regulation are central to all known forms of life and impinge on biological arenas as varied as agriculture, biotechnology, and medicine. Otherwise known as translation and translational control, these processes have been investigated with increasing intensity since the middle of the 20th century, and in increasing depth with advances in molecular and cell biology. We review the origins of the field, focusing on the underlying concepts and early studies of the cellular machinery and mechanisms involved. We highlight key discoveries and events on a timeline, consider areas where current research has engendered new ideas, and conclude with some speculation on future directions for the field.
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Affiliation(s)
- Soroush Tahmasebi
- Department of Biochemistry and Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
| | - John W B Hershey
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California 95616
| | - Michael B Mathews
- Department of Medicine, Rutgers New Jersey Medical School, Newark, New Jersey 07103
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10
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The Structural and Functional Organization of Ribosomal Compartment in the Cell: A Mystery or a Reality? Trends Biochem Sci 2018; 43:938-950. [PMID: 30337135 DOI: 10.1016/j.tibs.2018.09.017] [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: 04/27/2018] [Revised: 09/21/2018] [Accepted: 09/21/2018] [Indexed: 11/23/2022]
Abstract
Great progress has been made toward solving the atomic structure of the ribosome, which is the main biosynthetic machine in cells, but we still do not have a full picture of exactly how cellular ribosomes function. Based on the analysis of crystallographic and electron microscopy data, we propose a basic model of the structural organization of ribosomes into a compartment. This compartment is regularly formed by arrays of ribosomal tetramers made up of two dimers that are actually facing in opposite directions. The compartment functions as the main 'factory' for the production of cellular proteins. The model is consistent with the existing biochemical and genetic data. We also consider the functional connections of such a compartment with cellular transcription and ribosomal biogenesis.
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11
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Khong A, Parker R. mRNP architecture in translating and stress conditions reveals an ordered pathway of mRNP compaction. J Cell Biol 2018; 217:4124-4140. [PMID: 30322972 PMCID: PMC6279387 DOI: 10.1083/jcb.201806183] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/05/2018] [Accepted: 10/04/2018] [Indexed: 12/31/2022] Open
Abstract
Khong and Parker use single-molecule FISH to examine the timing of mRNA entry to stress granule as well as mRNA protein complex (mRNP) architecture. mRNA compaction increases after ribosome runoff, suggesting that mRNPs preferentially adopt a closed-loop structure in nontranslating conditions. Stress granules (SGs) are transient membraneless organelles of nontranslating mRNA–protein complexes (mRNPs) that form during stress. In this study, we used multiple single-molecule FISH probes for particular mRNAs to examine their SG recruitment and spatial organization. Ribosome runoff is required for SG entry, as long open reading frame (ORF) mRNAs are delayed in SG accumulation, indicating that the SG transcriptome changes over time. Moreover, mRNAs are ∼20× compacted from an expected linear length when translating and compact ∼2-fold further in a stepwise manner beginning at the 5′ end during ribosome runoff. Surprisingly, the 5′ and 3′ ends of the examined mRNAs were separated when translating, but in nontranslating conditions the ends of long ORF mRNAs become close, suggesting that the closed-loop model of mRNPs preferentially forms on nontranslating mRNAs. Compaction of ribosome-free mRNAs is ATP independent, consistent with compaction occurring through RNA structure formation. These results suggest that translation inhibition triggers an mRNP reorganization that brings ends closer, which has implications for the regulation of mRNA stability and translation by 3′ UTR elements and the poly(A) tail.
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Affiliation(s)
- Anthony Khong
- Howard Hughes Medical Institute, University of Colorado, Boulder, CO.,Department of Biochemistry, University of Colorado, Boulder, CO
| | - Roy Parker
- Howard Hughes Medical Institute, University of Colorado, Boulder, CO .,Department of Biochemistry, University of Colorado, Boulder, CO
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12
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Ostroff LE, Watson DJ, Cao G, Parker PH, Smith H, Harris KM. Shifting patterns of polyribosome accumulation at synapses over the course of hippocampal long-term potentiation. Hippocampus 2018; 28:416-430. [PMID: 29575288 DOI: 10.1002/hipo.22841] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 02/28/2018] [Accepted: 03/11/2018] [Indexed: 11/09/2022]
Abstract
Hippocampal long-term potentiation (LTP) is a cellular memory mechanism. For LTP to endure, new protein synthesis is required immediately after induction and some of these proteins must be delivered to specific, presumably potentiated, synapses. Local synthesis in dendrites could rapidly provide new proteins to synapses, but the spatial distribution of translation following induction of LTP is not known. Here, we quantified polyribosomes, the sites of local protein synthesis, in CA1 stratum radiatum dendrites and spines from postnatal day 15 rats. Hippocampal slices were rapidly fixed at 5, 30, or 120 min after LTP induction by theta-burst stimulation (TBS). Dendrites were reconstructed through serial section electron microscopy from comparable regions near the TBS or control electrodes in the same slice, and in unstimulated hippocampus that was perfusion-fixed in vivo. At 5 min after induction of LTP, polyribosomes were elevated in dendritic shafts and spines, especially near spine bases and in spine heads. At 30 min, polyribosomes remained elevated only in spine bases. At 120 min, both spine bases and spine necks had elevated polyribosomes. Polyribosomes accumulated in spines with larger synapses at 5 and 30 min, but not at 120 min. Small spines, meanwhile, proliferated dramatically by 120 min, but these largely lacked polyribosomes. The number of ribosomes per polyribosome is variable and may reflect differences in translation regulation. In dendritic spines, but not shafts, there were fewer ribosomes per polyribosome in the slice conditions relative to in vivo, but this recovered transiently in the 5 min LTP condition. Overall, our data show that LTP induces a rapid, transient upregulation of large polyribosomes in larger spines, and a persistent upregulation of small polyribosomes in the bases and necks of small spines. This is consistent with local translation supporting enlargement of potentiated synapses within minutes of LTP induction.
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Affiliation(s)
- Linnaea E Ostroff
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Deborah J Watson
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Guan Cao
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Patrick H Parker
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Heather Smith
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
| | - Kristen M Harris
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78731
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13
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Shirokikh NE, Preiss T. Translation initiation by cap-dependent ribosome recruitment: Recent insights and open questions. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1473. [PMID: 29624880 DOI: 10.1002/wrna.1473] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 02/02/2018] [Accepted: 02/14/2018] [Indexed: 12/14/2022]
Abstract
Gene expression universally relies on protein synthesis, where ribosomes recognize and decode the messenger RNA template by cycling through translation initiation, elongation, and termination phases. All aspects of translation have been studied for decades using the tools of biochemistry and molecular biology available at the time. Here, we focus on the mechanism of translation initiation in eukaryotes, which is remarkably more complex than prokaryotic initiation and is the target of multiple types of regulatory intervention. The "consensus" model, featuring cap-dependent ribosome entry and scanning of mRNA leader sequences, represents the predominantly utilized initiation pathway across eukaryotes, although several variations of the model and alternative initiation mechanisms are also known. Recent advances in structural biology techniques have enabled remarkable molecular-level insights into the functional states of eukaryotic ribosomes, including a range of ribosomal complexes with different combinations of translation initiation factors that are thought to represent bona fide intermediates of the initiation process. Similarly, high-throughput sequencing-based ribosome profiling or "footprinting" approaches have allowed much progress in understanding the elongation phase of translation, and variants of them are beginning to reveal the remaining mysteries of initiation, as well as aspects of translation termination and ribosomal recycling. A current view on the eukaryotic initiation mechanism is presented here with an emphasis on how recent structural and footprinting results underpin axioms of the consensus model. Along the way, we further outline some contested mechanistic issues and major open questions still to be addressed. This article is categorized under: Translation > Translation Mechanisms Translation > Translation Regulation RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Nikolay E Shirokikh
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, Australia
| | - Thomas Preiss
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, Australia
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14
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Bussey KA, Lau U, Schumann S, Gallo A, Osbelt L, Stempel M, Arnold C, Wissing J, Gad HH, Hartmann R, Brune W, Jänsch L, Whitehouse A, Brinkmann MM. The interferon-stimulated gene product oligoadenylate synthetase-like protein enhances replication of Kaposi's sarcoma-associated herpesvirus (KSHV) and interacts with the KSHV ORF20 protein. PLoS Pathog 2018; 14:e1006937. [PMID: 29499066 PMCID: PMC5851652 DOI: 10.1371/journal.ppat.1006937] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/14/2018] [Accepted: 02/12/2018] [Indexed: 12/23/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is one of the few oncogenic human viruses known to date. Its large genome encodes more than 85 proteins and includes both unique viral proteins as well as proteins conserved amongst herpesviruses. KSHV ORF20 is a member of the herpesviral core UL24 family, but the function of ORF20 and its role in the viral life cycle is not well understood. ORF20 encodes three largely uncharacterized isoforms, which we found were localized predominantly in the nuclei and nucleoli. Quantitative affinity purification coupled to mass spectrometry (q-AP-MS) identified numerous specific interacting partners of ORF20, including ribosomal proteins and the interferon-stimulated gene product (ISG) oligoadenylate synthetase-like protein (OASL). Both endogenous and transiently transfected OASL co-immunoprecipitated with ORF20, and this interaction was conserved among all ORF20 isoforms and multiple ORF20 homologs of the UL24 family in other herpesviruses. Characterization of OASL interacting partners by q-AP-MS identified a very similar interactome to that of ORF20. Both ORF20 and OASL copurified with 40S and 60S ribosomal subunits, and when they were co-expressed, they associated with polysomes. Although ORF20 did not have a global effect on translation, ORF20 enhanced RIG-I induced expression of endogenous OASL in an IRF3-dependent but IFNAR-independent manner. OASL has been characterized as an ISG with antiviral activity against some viruses, but its role for gammaherpesviruses was unknown. We show that OASL and ORF20 mRNA expression were induced early after reactivation of latently infected HuARLT-rKSHV.219 cells. Intriguingly, we found that OASL enhanced infection of KSHV. During infection with a KSHV ORF20stop mutant, however, OASL-dependent enhancement of infectivity was lost. Our data have characterized the interaction of ORF20 with OASL and suggest ORF20 usurps the function of OASL to benefit KSHV infection. The herpesviruses are a family of large double-stranded DNA viruses that cause a variety of illnesses from chicken pox to cancer. Kaposi’s sarcoma-associated herpesvirus (KSHV) is a cancer-causing herpesvirus and can lead to development of Kaposi’s sarcoma, a major form of cancer in HIV-positive patients. As for all herpesviruses, infection with KSHV is lifelong. Exactly how KSHV initiates and maintains its infection is still not well understood, but it must manipulate the host cell to establish favorable conditions. Likewise, the host has developed a complicated system to fight off invaders, which includes the production of interferon-stimulated gene products. We have now found that KSHV exploits one such host cell protein, the oligoadenylate synthetase-like protein (OASL). Rather than OASL acting as an antiviral protein as it does during many other viral infections, KSHV appears to have found a way to utilize OASL for its own benefit. The KSHV protein ORF20 interacts with OASL, they co-localize in nucleoli, and both ORF20 and OASL associate and purify with components of the cellular translational machinery. This may help viral infection by selectively controlling protein production.
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Affiliation(s)
- Kendra A. Bussey
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Ulrike Lau
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Sophie Schumann
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Antonio Gallo
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Lisa Osbelt
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Markus Stempel
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Christine Arnold
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Josef Wissing
- Cellular Proteomics Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Hans Henrik Gad
- Center for Structural Biology, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Rune Hartmann
- Center for Structural Biology, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Wolfram Brune
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Lothar Jänsch
- Cellular Proteomics Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Adrian Whitehouse
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Melanie M. Brinkmann
- Viral Immune Modulation Research Group, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
- Institute of Virology, Hannover Medical School, Hannover, Germany
- * E-mail:
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15
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Afonina ZA, Shirokov VA. Three-Dimensional Organization of Polyribosomes–A Modern Approach. BIOCHEMISTRY (MOSCOW) 2018; 83:S48-S55. [DOI: 10.1134/s0006297918140055] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Diament A, Feldman A, Schochet E, Kupiec M, Arava Y, Tuller T. The extent of ribosome queuing in budding yeast. PLoS Comput Biol 2018; 14:e1005951. [PMID: 29377894 PMCID: PMC5805374 DOI: 10.1371/journal.pcbi.1005951] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 02/08/2018] [Accepted: 01/05/2018] [Indexed: 11/18/2022] Open
Abstract
Ribosome queuing is a fundamental phenomenon suggested to be related to topics such as genome evolution, synthetic biology, gene expression regulation, intracellular biophysics, and more. However, this phenomenon hasn't been quantified yet at a genomic level. Nevertheless, methodologies for studying translation (e.g. ribosome footprints) are usually calibrated to capture only single ribosome protected footprints (mRPFs) and thus limited in their ability to detect ribosome queuing. On the other hand, most of the models in the field assume and analyze a certain level of queuing. Here we present an experimental-computational approach for studying ribosome queuing based on sequencing of RNA footprints extracted from pairs of ribosomes (dRPFs) using a modified ribosome profiling protocol. We combine our approach with traditional ribosome profiling to generate a detailed profile of ribosome traffic. The data are analyzed using computational models of translation dynamics. The approach was implemented on the Saccharomyces cerevisiae transcriptome. Our data shows that ribosome queuing is more frequent than previously thought: the measured ratio of ribosomes within dRPFs to mRPFs is 0.2–0.35, suggesting that at least one to five translating ribosomes is in a traffic jam; these queued ribosomes cannot be captured by traditional methods. We found that specific regions are enriched with queued ribosomes, such as the 5’-end of ORFs, and regions upstream to mRPF peaks, among others. While queuing is related to higher density of ribosomes on the transcript (characteristic of highly translated genes), we report cases where traffic jams are relatively more severe in lowly expressed genes and possibly even selected for. In addition, our analysis demonstrates that higher adaptation of the coding region to the intracellular tRNA levels is associated with lower queuing levels. Our analysis also suggests that the Saccharomyces cerevisiae transcriptome undergoes selection for eliminating traffic jams. Thus, our proposed approach is an essential tool for high resolution analysis of ribosome traffic during mRNA translation and understanding its evolution. During translation, multiple ribosomes may translate the same mRNA. The density of ribosomal traffic across the transcript poses several open questions, such as how often a ribosome’s path is blocked by a second ribosome, do queues of multiple ribosomes typically form on mRNAs and what is their effect on the overall translation rate of an mRNA. However, this phenomenon hasn't been quantified yet at a genomic level. Nevertheless, methodologies for monitoring translation are limited in their ability to detect ribosome queuing. On the other hand, most of the models in the field assume and analyze a certain level of queuing. Here we present an experimental-computational approach for studying ribosome queuing based on sequencing of RNA footprints extracted from pairs of adjacent translating ribosomes, and a computational model of translation dynamics. Our data shows that ribosome queuing in Saccharomyces cerevisiae is more frequent than previously thought, suggesting that at least one to five translating ribosomes is in a traffic jam; these queued ribosomes cannot be captured by traditional methods. Our analysis also suggests that the S. cerevisiae transcriptome undergoes selection for eliminating traffic jams, while specific regions and genes may possibly be under selection for increased queuing.
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Affiliation(s)
- Alon Diament
- Biomedical Engineering Dept., Tel Aviv University, Tel Aviv, Israel
| | - Anna Feldman
- Biomedical Engineering Dept., Tel Aviv University, Tel Aviv, Israel
| | - Elisheva Schochet
- The Blavatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Martin Kupiec
- Dept. of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Yoav Arava
- Biology Dept., Technion-Israel Institute of Technology, Haifa, Israel
| | - Tamir Tuller
- Biomedical Engineering Dept., Tel Aviv University, Tel Aviv, Israel
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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17
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Gold VA, Chroscicki P, Bragoszewski P, Chacinska A. Visualization of cytosolic ribosomes on the surface of mitochondria by electron cryo-tomography. EMBO Rep 2017; 18:1786-1800. [PMID: 28827470 PMCID: PMC5623831 DOI: 10.15252/embr.201744261] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/11/2017] [Accepted: 07/14/2017] [Indexed: 12/31/2022] Open
Abstract
We employed electron cryo‐tomography to visualize cytosolic ribosomes on the surface of mitochondria. Translation‐arrested ribosomes reveal the clustered organization of the TOM complex, corroborating earlier reports of localized translation. Ribosomes are shown to interact specifically with the TOM complex, and nascent chain binding is crucial for ribosome recruitment and stabilization. Ribosomes are bound to the membrane in discrete clusters, often in the vicinity of the crista junctions. This interaction highlights how protein synthesis may be coupled with transport. Our work provides unique insights into the spatial organization of cytosolic ribosomes on mitochondria.
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Affiliation(s)
- Vicki Am Gold
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany .,Living Systems Institute, University of Exeter, Exeter, UK.,College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Piotr Chroscicki
- The International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Piotr Bragoszewski
- The International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Agnieszka Chacinska
- The International Institute of Molecular and Cell Biology, Warsaw, Poland .,Centre of New Technologies, University of Warsaw, Warsaw, Poland
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18
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Polysome profiling of mAb producing CHO cell lines links translational control of cell proliferation and recombinant mRNA loading onto ribosomes with global and recombinant protein synthesis. Biotechnol J 2017; 12. [DOI: 10.1002/biot.201700177] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 05/07/2017] [Accepted: 05/15/2017] [Indexed: 12/13/2022]
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19
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mRNA length-sensing in eukaryotic translation: reconsidering the "closed loop" and its implications for translational control. Curr Genet 2016; 63:613-620. [PMID: 28028558 DOI: 10.1007/s00294-016-0674-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 12/14/2016] [Accepted: 12/15/2016] [Indexed: 01/01/2023]
Abstract
Most eukaryotic mRNAs are recruited to the ribosome by recognition of a 5' m7GpppN cap. 30 years of genetic and biochemical evidence point to a role for interaction between the 5' cap-interacting factors and the 3' poly(A)-binding protein in bringing the ends of the mRNA into close proximity and promoting both translation and stability of the mRNA, in a form known as the "closed loop". However, the results of recent RNA-protein interaction studies suggest that not all mRNAs have equal access to the closed loop factors. Furthermore, association with closed loop factors appears to be highly biased towards mRNAs with short open reading frames, echoing the trend for higher translation of short mRNAs that has been observed in many eukaryotes. We recently reported that the ribosomal signaling scaffold protein RACK1 promotes the efficient translation of short mRNAs that strongly associate with the closed loop factors. Here, we discuss the implications of these observations with respect to translational control and suggest avenues through which the universality of the closed loop in eukaryotic translation could be revisited.
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20
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Zur H, Tuller T. Predictive biophysical modeling and understanding of the dynamics of mRNA translation and its evolution. Nucleic Acids Res 2016; 44:9031-9049. [PMID: 27591251 PMCID: PMC5100582 DOI: 10.1093/nar/gkw764] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/19/2016] [Indexed: 12/12/2022] Open
Abstract
mRNA translation is the fundamental process of decoding the information encoded in mRNA molecules by the ribosome for the synthesis of proteins. The centrality of this process in various biomedical disciplines such as cell biology, evolution and biotechnology, encouraged the development of dozens of mathematical and computational models of translation in recent years. These models aimed at capturing various biophysical aspects of the process. The objective of this review is to survey these models, focusing on those based and/or validated on real large-scale genomic data. We consider aspects such as the complexity of the models, the biophysical aspects they regard and the predictions they may provide. Furthermore, we survey the central systems biology discoveries reported on their basis. This review demonstrates the fundamental advantages of employing computational biophysical translation models in general, and discusses the relative advantages of the different approaches and the challenges in the field.
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Affiliation(s)
- Hadas Zur
- Department of Biomedical Engineering, the Engineering Faculty, Tel Aviv University, Tel-Aviv 69978, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, the Engineering Faculty, Tel Aviv University, Tel-Aviv 69978, Israel
- The Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv 69978, Israel
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21
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Morisaki T, Lyon K, DeLuca KF, DeLuca JG, English BP, Zhang Z, Lavis LD, Grimm JB, Viswanathan S, Looger LL, Lionnet T, Stasevich TJ. Real-time quantification of single RNA translation dynamics in living cells. Science 2016; 352:1425-9. [PMID: 27313040 DOI: 10.1126/science.aaf0899] [Citation(s) in RCA: 237] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/28/2016] [Indexed: 12/14/2022]
Abstract
Although messenger RNA (mRNA) translation is a fundamental biological process, it has never been imaged in real time in vivo with single-molecule precision. To achieve this, we developed nascent chain tracking (NCT), a technique that uses multi-epitope tags and antibody-based fluorescent probes to quantify protein synthesis dynamics at the single-mRNA level. NCT reveals an elongation rate of ~10 amino acids per second, with initiation occurring stochastically every ~30 seconds. Polysomes contain ~1 ribosome every 200 to 900 nucleotides and are globular rather than elongated in shape. By developing multicolor probes, we showed that most polysomes act independently; however, a small fraction (~5%) form complexes in which two distinct mRNAs can be translated simultaneously. The sensitivity and versatility of NCT make it a powerful new tool for quantifying mRNA translation kinetics.
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Affiliation(s)
- Tatsuya Morisaki
- Department of Biochemistry and Molecular Biology and Institute for Genome Architecture and Function, Colorado State University, Fort Collins, CO, USA
| | - Kenneth Lyon
- Department of Biochemistry and Molecular Biology and Institute for Genome Architecture and Function, Colorado State University, Fort Collins, CO, USA
| | - Keith F DeLuca
- Department of Biochemistry and Molecular Biology and Institute for Genome Architecture and Function, Colorado State University, Fort Collins, CO, USA
| | - Jennifer G DeLuca
- Department of Biochemistry and Molecular Biology and Institute for Genome Architecture and Function, Colorado State University, Fort Collins, CO, USA
| | - Brian P English
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Zhengjian Zhang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jonathan B Grimm
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Sarada Viswanathan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Timothee Lionnet
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Timothy J Stasevich
- Department of Biochemistry and Molecular Biology and Institute for Genome Architecture and Function, Colorado State University, Fort Collins, CO, USA
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22
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Lunelli L, Bernabò P, Bolner A, Vaghi V, Marchioretto M, Viero G. Peering at Brain Polysomes with Atomic Force Microscopy. J Vis Exp 2016. [PMID: 27023752 DOI: 10.3791/53851] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The translational machinery, i.e., the polysome or polyribosome, is one of the biggest and most complex cytoplasmic machineries in cells. Polysomes, formed by ribosomes, mRNAs, several proteins and non-coding RNAs, represent integrated platforms where translational controls take place. However, while the ribosome has been widely studied, the organization of polysomes is still lacking comprehensive understanding. Thus much effort is required in order to elucidate polysome organization and any novel mechanism of translational control that may be embedded. Atomic force microscopy (AFM) is a type of scanning probe microscopy that allows the acquisition of 3D images at nanoscale resolution. Compared to electron microscopy (EM) techniques, one of the main advantages of AFM is that it can acquire thousands of images both in air and in solution, enabling the sample to be maintained under near physiological conditions without any need for staining and fixing procedures. Here, a detailed protocol for the accurate purification of polysomes from mouse brain and their deposition on mica substrates is described. This protocol enables polysome imaging in air and liquid with AFM and their reconstruction as three-dimensional objects. Complementary to cryo-electron microscopy (cryo-EM), the proposed method can be conveniently used for systematically analyzing polysomes and studying their organization.
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Affiliation(s)
- Lorenzo Lunelli
- Laboratory of Biomolecular Sequence and Structure Analysis for Health, Fondazione Bruno Kessler
| | | | | | - Valentina Vaghi
- Laboratory of Biomolecular Sequence and Structure Analysis for Health, Fondazione Bruno Kessler
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23
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Floor SN, Doudna JA. Tunable protein synthesis by transcript isoforms in human cells. eLife 2016; 5:e10921. [PMID: 26735365 DOI: 10.7554/elife.10921.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/05/2016] [Indexed: 05/25/2023] Open
Abstract
Eukaryotic genes generate multiple RNA transcript isoforms though alternative transcription, splicing, and polyadenylation. However, the relationship between human transcript diversity and protein production is complex as each isoform can be translated differently. We fractionated a polysome profile and reconstructed transcript isoforms from each fraction, which we term Transcript Isoforms in Polysomes sequencing (TrIP-seq). Analysis of these data revealed regulatory features that control ribosome occupancy and translational output of each transcript isoform. We extracted a panel of 5' and 3' untranslated regions that control protein production from an unrelated gene in cells over a 100-fold range. Select 5' untranslated regions exert robust translational control between cell lines, while 3' untranslated regions can confer cell type-specific expression. These results expose the large dynamic range of transcript-isoform-specific translational control, identify isoform-specific sequences that control protein output in human cells, and demonstrate that transcript isoform diversity must be considered when relating RNA and protein levels.
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Affiliation(s)
- Stephen N Floor
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
- Innovative Genomics Initiative, University of California, Berkeley, Berkeley, United States
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
- Department of Chemistry, University of California, Berkeley, Berkeley, California, United States
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24
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Floor SN, Doudna JA. Tunable protein synthesis by transcript isoforms in human cells. eLife 2016; 5. [PMID: 26735365 PMCID: PMC4764583 DOI: 10.7554/elife.10921] [Citation(s) in RCA: 184] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/05/2016] [Indexed: 12/27/2022] Open
Abstract
Eukaryotic genes generate multiple RNA transcript isoforms though alternative transcription, splicing, and polyadenylation. However, the relationship between human transcript diversity and protein production is complex as each isoform can be translated differently. We fractionated a polysome profile and reconstructed transcript isoforms from each fraction, which we term Transcript Isoforms in Polysomes sequencing (TrIP-seq). Analysis of these data revealed regulatory features that control ribosome occupancy and translational output of each transcript isoform. We extracted a panel of 5′ and 3′ untranslated regions that control protein production from an unrelated gene in cells over a 100-fold range. Select 5′ untranslated regions exert robust translational control between cell lines, while 3′ untranslated regions can confer cell type-specific expression. These results expose the large dynamic range of transcript-isoform-specific translational control, identify isoform-specific sequences that control protein output in human cells, and demonstrate that transcript isoform diversity must be considered when relating RNA and protein levels. DOI:http://dx.doi.org/10.7554/eLife.10921.001 To produce a protein, a gene’s DNA is first copied to make molecules of messenger RNA (mRNA). The mRNAs pass through a molecular machine known as the ribosome, which translates the genetic code to make a protein. Not all of an mRNA is translated to make a protein; the “untranslated” regions play crucial roles in regulating how much of the protein is produced. In animals, plants and other eukaryotes, many mRNAs are made up of small pieces that are “spliced” together. During this process, proteins are deposited on the mRNA to mark the splice junctions, which are then cleared when the mRNA is translated. Many different mRNAs can be produced from the same gene by splicing different combinations of RNA pieces. Each of these mRNA “isoforms” can, in principle, contain a unique set of features that control its translation. Hence each mRNA isoform can be translated differently so that different amounts of the corresponding protein product are produced. However, the relationship between the variety of isoforms and the control of translation is complex and not well understood. To address these questions, Floor and Doudna measured the translation of over 60,000 mRNA isoforms made from almost 14,000 human genes. The experiments show that untranslated regions at the end of the mRNA (known as the 3′ end) strongly influence translation, even if the protein coding regions remain the same. Furthermore, the data showed that mRNAs with more splice junctions are translated better, implying an mRNA has some sort of memory of how many junctions it had even after the protein markers have been cleared. Next, Floor and Doudna inserted regulatory sequences from differently translated isoforms into an unrelated “reporter” gene. This dramatically changed the amount of protein produced from the reporter gene, in a manner predicted by the earlier experiments. Untranslated regions at the beginning of the mRNAs (known as the 5′ end) controlled the amount of protein produced from the reporter consistently across different types of cells from the body. On the other hand, the 3′ regions can tune the level of protein production in particular types of cells. Floor and Doudna’s findings demonstrate that differences between mRNA isoforms of a gene can have a big effect on the level of protein production. Changes in the types of mRNA made from a gene are often associated with human diseases, and these findings suggest one reason why. Additionally, the ability to engineer translation of an mRNA using the data is likely to aid the development of mRNA-based therapies. DOI:http://dx.doi.org/10.7554/eLife.10921.002
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Affiliation(s)
- Stephen N Floor
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.,Innovative Genomics Initiative, University of California, Berkeley, Berkeley, United States.,Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Chemistry, University of California, Berkeley, Berkeley, California, United States
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25
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Fan AC, Leung AKL. RNA Granules and Diseases: A Case Study of Stress Granules in ALS and FTLD. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 907:263-96. [PMID: 27256390 DOI: 10.1007/978-3-319-29073-7_11] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
RNA granules are microscopically visible cellular structures that aggregate by protein-protein and protein-RNA interactions. Using stress granules as an example, we discuss the principles of RNA granule formation, which rely on the multivalency of RNA and multi-domain proteins as well as low-affinity interactions between proteins with prion-like/low-complexity domains (e.g. FUS and TDP-43). We then explore how dysregulation of RNA granule formation is linked to neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), and discuss possible strategies for therapeutic intervention.
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Affiliation(s)
- Alexander C Fan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Anthony K L Leung
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
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Lauria F, Tebaldi T, Lunelli L, Struffi P, Gatto P, Pugliese A, Brigotti M, Montanaro L, Ciribilli Y, Inga A, Quattrone A, Sanguinetti G, Viero G. RiboAbacus: a model trained on polyribosome images predicts ribosome density and translational efficiency from mammalian transcriptomes. Nucleic Acids Res 2015; 43:e153. [PMID: 26240374 PMCID: PMC4678843 DOI: 10.1093/nar/gkv781] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/20/2015] [Indexed: 01/14/2023] Open
Abstract
Fluctuations in mRNA levels only partially contribute to determine variations in mRNA availability for translation, producing the well-known poor correlation between transcriptome and proteome data. Recent advances in microscopy now enable researchers to obtain high resolution images of ribosomes on transcripts, providing precious snapshots of translation in vivo. Here we propose RiboAbacus, a mathematical model that for the first time incorporates imaging data in a predictive model of transcript-specific ribosome densities and translational efficiencies. RiboAbacus uses a mechanistic model of ribosome dynamics, enabling the quantification of the relative importance of different features (such as codon usage and the 5′ ramp effect) in determining the accuracy of predictions. The model has been optimized in the human Hek-293 cell line to fit thousands of images of human polysomes obtained by atomic force microscopy, from which we could get a reference distribution of the number of ribosomes per mRNA with unmatched resolution. After validation, we applied RiboAbacus to three case studies of known transcriptome-proteome datasets for estimating the translational efficiencies, resulting in an increased correlation with corresponding proteomes. RiboAbacus is an intuitive tool that allows an immediate estimation of crucial translation properties for entire transcriptomes, based on easily obtainable transcript expression levels.
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Affiliation(s)
- Fabio Lauria
- Institute of Biophysics, CNR Unit at Trento, Via alla Cascata, 56/C-38123 Povo (TN), Italy
| | - Toma Tebaldi
- Laboratory of Translational Genomics, Centre for Integrative Biology, Via delle Regole, 101-38123 Mattarello (TN), Italy
| | - Lorenzo Lunelli
- Laboratory of Biomolecular Sequence and Structure Analysis for Health, Fondazione Bruno Kessler, Via Sommarive, 18-38123 Povo (TN), Italy
| | - Paolo Struffi
- Laboratory of Translational Genomics, Centre for Integrative Biology, Via delle Regole, 101-38123 Mattarello (TN), Italy
| | - Pamela Gatto
- Laboratory of Translational Genomics, Centre for Integrative Biology, Via delle Regole, 101-38123 Mattarello (TN), Italy
| | - Andrea Pugliese
- Mathematics Department, University of Trento, Via Sommarive, 14-38123 Povo (TN), Italy
| | - Maurizio Brigotti
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Via S. Giacomo, 14-40126 Bologna, Italy
| | - Lorenzo Montanaro
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Via S. Giacomo, 14-40126 Bologna, Italy
| | - Yari Ciribilli
- Laboratory of Transcriptional Networks, Centre for Integrative Biology, Via delle Regole, 101-38123 Mattarello (TN), Italy
| | - Alberto Inga
- Laboratory of Transcriptional Networks, Centre for Integrative Biology, Via delle Regole, 101-38123 Mattarello (TN), Italy
| | - Alessandro Quattrone
- Laboratory of Translational Genomics, Centre for Integrative Biology, Via delle Regole, 101-38123 Mattarello (TN), Italy
| | - Guido Sanguinetti
- School of Informatics, University of Edinburgh, 10 Crichton Street, Edinburgh, Midlothian EH8 9AB, UK
| | - Gabriella Viero
- Institute of Biophysics, CNR Unit at Trento, Via alla Cascata, 56/C-38123 Povo (TN), Italy
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Viero G, Lunelli L, Passerini A, Bianchini P, Gilbert RJ, Bernabò P, Tebaldi T, Diaspro A, Pederzolli C, Quattrone A. Three distinct ribosome assemblies modulated by translation are the building blocks of polysomes. ACTA ACUST UNITED AC 2015; 208:581-96. [PMID: 25713412 PMCID: PMC4347638 DOI: 10.1083/jcb.201406040] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Translation is increasingly recognized as a central control layer of gene expression in eukaryotic cells. The overall organization of mRNA and ribosomes within polysomes, as well as the possible role of this organization in translation are poorly understood. Here we show that polysomes are primarily formed by three distinct classes of ribosome assemblies. We observe that these assemblies can be connected by naked RNA regions of the transcript. We show that the relative proportions of the three classes of ribosome assemblies reflect, and probably dictate, the level of translational activity. These results reveal the existence of recurrent supra-ribosomal building blocks forming polysomes and suggest the presence of unexplored translational controls embedded in the polysome structure.
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Affiliation(s)
- Gabriella Viero
- Institute of Biophysics, National Research Council (CNR) Unit at Trento, 38123 Povo, Italy Laboratory of Translational Genomics, Centre for Integrative Biology, University of Trento, 38123 Mattarello, Italy
| | - Lorenzo Lunelli
- Laboratory of Biomolecular Sequence and Structure Analysis for Health, Fondazione Bruno Kessler, 38123 Povo, Italy
| | - Andrea Passerini
- Department of Information Engineering and Computer Science, University of Trento, 38123 Povo, Italy
| | - Paolo Bianchini
- Nanophysics Department, Italian Institute of Technology, 16163 Genova, Italy
| | - Robert J Gilbert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England, UK
| | - Paola Bernabò
- Institute of Biophysics, National Research Council (CNR) Unit at Trento, 38123 Povo, Italy
| | - Toma Tebaldi
- Laboratory of Translational Genomics, Centre for Integrative Biology, University of Trento, 38123 Mattarello, Italy
| | - Alberto Diaspro
- Nanophysics Department, Italian Institute of Technology, 16163 Genova, Italy
| | - Cecilia Pederzolli
- Laboratory of Biomolecular Sequence and Structure Analysis for Health, Fondazione Bruno Kessler, 38123 Povo, Italy
| | - Alessandro Quattrone
- Laboratory of Translational Genomics, Centre for Integrative Biology, University of Trento, 38123 Mattarello, Italy
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Mrazek J, Toso D, Ryazantsev S, Zhang X, Zhou ZH, Fernandez BC, Kickhoefer VA, Rome LH. Polyribosomes are molecular 3D nanoprinters that orchestrate the assembly of vault particles. ACS NANO 2014; 8:11552-9. [PMID: 25354757 PMCID: PMC4245718 DOI: 10.1021/nn504778h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Ribosomes are molecular machines that function in polyribosome complexes to translate genetic information, guide the synthesis of polypeptides, and modulate the folding of nascent proteins. Here, we report a surprising function for polyribosomes as a result of a systematic examination of the assembly of a large ribonucleoprotein complex, the vault particle. Structural and functional evidence points to a model of vault assembly whereby the polyribosome acts like a 3D nanoprinter to direct the ordered translation and assembly of the multi-subunit vault homopolymer, a process which we refer to as polyribosome templating. Structure-based mutagenesis and cell-free in vitro expression studies further demonstrated the critical importance of the polyribosome in vault assembly. Polyribosome templating prevents chaos by ensuring efficiency and order in the production of large homopolymeric protein structures in the crowded cellular environment and might explain the origin of many polyribosome-associated molecular assemblies inside the cell.
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Affiliation(s)
- Jan Mrazek
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
- Address correspondence to ,
| | - Daniel Toso
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Sergey Ryazantsev
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Xing Zhang
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Z. Hong Zhou
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Beatriz Campo Fernandez
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Valerie A. Kickhoefer
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Leonard H. Rome
- Department of Biological Chemistry, David Geffen School of Medicine, Department of Microbiology, Immunology & Molecular Genetics, and California Nanosystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
- Address correspondence to ,
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Myasnikov AG, Afonina ZA, Ménétret JF, Shirokov VA, Spirin AS, Klaholz BP. The molecular structure of the left-handed supra-molecular helix of eukaryotic polyribosomes. Nat Commun 2014; 5:5294. [PMID: 25376914 DOI: 10.1038/ncomms6294] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 09/17/2014] [Indexed: 01/07/2023] Open
Abstract
During protein synthesis, several ribosomes bind to a single messenger RNA (mRNA) forming large macromolecular assemblies called polyribosomes. Here we report the detailed molecular structure of a 100 MDa eukaryotic poly-ribosome complex derived from cryo electron tomography, sub-tomogram averaging and pseudo-atomic modelling by crystal structure fitting. The structure allowed the visualization of the three functional parts of the polysome assembly, the central core region that forms a rather compact left-handed supra-molecular helix, and the more open regions that harbour the initiation and termination sites at either ends. The helical region forms a continuous mRNA channel where the mRNA strand bridges neighbouring exit and entry sites of the ribosomes and prevents mRNA looping between ribosomes. This structure provides unprecedented insights into protein- and RNA-mediated inter-ribosome contacts that involve conserved sites through 40S subunits and long protruding RNA expansion segments, suggesting a role in stabilizing the overall polyribosomal assembly.
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Affiliation(s)
- Alexander G Myasnikov
- 1] Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), 1 rue Laurent Fries, BP 10142, 67404 Illkirch, France [2] Centre National de la Recherche Scientifique (CNRS) UMR 7104, 67404 Illkirch, France [3] Institut National de la Santé et de la Recherche Médicale (INSERM), 67404 Illkirch, France [4] Université de Strasbourg, 67400 Strasbourg, France
| | - Zhanna A Afonina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Moscow, Russia
| | - Jean-François Ménétret
- 1] Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), 1 rue Laurent Fries, BP 10142, 67404 Illkirch, France [2] Centre National de la Recherche Scientifique (CNRS) UMR 7104, 67404 Illkirch, France [3] Institut National de la Santé et de la Recherche Médicale (INSERM), 67404 Illkirch, France [4] Université de Strasbourg, 67400 Strasbourg, France
| | - Vladimir A Shirokov
- Institute of Protein Research, Russian Academy of Sciences, 142290 Moscow, Russia
| | - Alexander S Spirin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Moscow, Russia
| | - Bruno P Klaholz
- 1] Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), 1 rue Laurent Fries, BP 10142, 67404 Illkirch, France [2] Centre National de la Recherche Scientifique (CNRS) UMR 7104, 67404 Illkirch, France [3] Institut National de la Santé et de la Recherche Médicale (INSERM), 67404 Illkirch, France [4] Université de Strasbourg, 67400 Strasbourg, France
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Afonina ZA, Myasnikov AG, Shirokov VA, Klaholz BP, Spirin AS. Formation of circular polyribosomes on eukaryotic mRNA without cap-structure and poly(A)-tail: a cryo electron tomography study. Nucleic Acids Res 2014; 42:9461-9. [PMID: 25016525 PMCID: PMC4132722 DOI: 10.1093/nar/gku599] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The polyribosomes newly formed on recombinant GFP-encoding mRNAs in a wheat germ cell-free translation system were analyzed using cryo-electron tomography, with sub-tomogram averaging of polysomal ribosomes and reconstruction of 3D structures of individual polyribosomes. The achieved level of resolution in the reconstructed polyribosomes allowed deducing the mRNA path by connecting adjacent exit and entry sites at the ribosomes inside each polyribosome. In this way, the circularity of a significant fraction (about 50%) of translating polyribosomes was proved in the case of the capped poly(A)-tailed mRNA, in agreement with the existing paradigm of the circularization via interaction of cap-bound initiation factor eIF4F with poly(A)-binding protein. However, translation of the capped mRNA construct without poly(A) tail, but with unspecific 3′-UTR derived from non-coding plasmid sequence, also led to the formation of circular polyribosomes in similar proportion (40%). Moreover, the polyribosomes formed on the uncapped non-polyadenylated mRNA with non-synergistic 5′- and 3′-UTRs proved to be circular as well, and appeared in the same proportion as in the previous cases. Thus, the formation of circular polyribosomes was found to be virtually independent of the presence of cap structure and poly(A) tail in mRNA, in contrast to the longstanding paradigm in the field.
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Affiliation(s)
- Zhanna A Afonina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Alexander G Myasnikov
- Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104 / Institut National de la Santé de la Recherche Médicale (INSERM) U964 / Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Vladimir A Shirokov
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Bruno P Klaholz
- Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104 / Institut National de la Santé de la Recherche Médicale (INSERM) U964 / Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Alexander S Spirin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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Lee KH, Kim SH, Kim HJ, Kim W, Lee HR, Jung Y, Choi JH, Hong KY, Jang SK, Kim KT. AUF1 contributes to Cryptochrome1 mRNA degradation and rhythmic translation. Nucleic Acids Res 2014; 42:3590-606. [PMID: 24423872 PMCID: PMC3973335 DOI: 10.1093/nar/gkt1379] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In the present study, we investigated the 3' untranslated region (UTR) of the mouse core clock gene cryptochrome 1 (Cry1) at the post-transcriptional level, particularly its translational regulation. Interestingly, the 3'UTR of Cry1 mRNA decreased its mRNA levels but increased protein amounts. The 3'UTR is widely known to function as a cis-acting element of mRNA degradation. The 3'UTR also provides a binding site for microRNA and mainly suppresses translation of target mRNAs. We found that AU-rich element RNA binding protein 1 (AUF1) directly binds to the Cry1 3'UTR and regulates translation of Cry1 mRNA. AUF1 interacted with eukaryotic translation initiation factor 3 subunit B and also directly associated with ribosomal protein S3 or ribosomal protein S14, resulting in translation of Cry1 mRNA in a 3'UTR-dependent manner. Expression of cytoplasmic AUF1 and binding of AUF1 to the Cry1 3'UTR were parallel to the circadian CRY1 protein profile. Our results suggest that the 3'UTR of Cry1 is important for its rhythmic translation, and AUF1 bound to the 3'UTR facilitates interaction with the 5' end of mRNA by interacting with translation initiation factors and recruiting the 40S ribosomal subunit to initiate translation of Cry1 mRNA.
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Affiliation(s)
- Kyung-Ha Lee
- Department of Life Sciences, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang, Gyeongbuk 790-784, Republic of Korea, School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang, Gyeongbuk 790-784, Republic of Korea and Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang, Gyeongbuk 790-784, Republic of Korea
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Afonina ZA, Myasnikov AG, Khabibullina NF, Belorusova AY, Menetret JF, Vasiliev VD, Klaholz BP, Shirokov VA, Spirin AS. Topology of mRNA chain in isolated eukaryotic double-row polyribosomes. BIOCHEMISTRY (MOSCOW) 2013; 78:445-54. [PMID: 23848146 DOI: 10.1134/s0006297913050027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the process of protein synthesis, the translating ribosomes of eukaryotic cells form polyribosomes that are found to be multiplex functional complexes possessing elements of ordered spatial organization. As revealed by a number of electron microscopy studies, the predominant visible configurations of the eukaryotic polyribosomes are circles (circular polyribosomes) and two-stranded formations (so-called double-row polyribosomes). The "long" (i.e. heavy loaded) polyribosomes are usually represented by double-row structures, which can be interpreted as either topologically circular ("collapsed rings"), or topologically linear (zigzags or helices). In the present work we have analyzed the mRNA path within the eukaryotic polyribosomes, isolated from a wheat germ cell-free translation system, by integrating two approaches: the visualization of mRNA ends in polyribosomes by marking them with gold nanoparticles (3'-end) and initiating 40S subunits (5'-end), as well as by the cryoelectron tomography. Examination of the location of the mRNA markers in polyribosomes and mutual orientation of ribosomes in them has shown that the double-row polyribosomes of the same sample can have both circular and linear arrangements of their mRNA.
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Affiliation(s)
- Zh A Afonina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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SHARMA AJEETK, CHOWDHURY DEBASHISH. TEMPLATE-DIRECTED BIOPOLYMERIZATION: TAPE-COPYING TURING MACHINES. ACTA ACUST UNITED AC 2013. [DOI: 10.1142/s1793048012300083] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
DNA, RNA and proteins are among the most important macromolecules in a living cell. These molecules are polymerized by molecular machines. These natural nano-machines polymerize such macromolecules, adding one monomer at a time, using another linear polymer as the corresponding template. The machine utilizes input chemical energy to move along the template which also serves as a track for the movements of the machine. In the Alan Turing year 2012, it is worth pointing out that these machines are "tape-copying Turing machines". We review the operational mechanisms of the polymerizer machines and their collective behavior from the perspective of statistical physics, emphasizing their common features in spite of the crucial differences in their biological functions. We also draw the attention of the physics community to another class of modular machines that carry out a different type of template-directed polymerization. We hope this review will inspire new kinetic models for these modular machines.
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Affiliation(s)
- AJEET K. SHARMA
- Department of Physics, Indian Institute of Technology, Kanpur 208016, India
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von der Haar T. Mathematical and Computational Modelling of Ribosomal Movement and Protein Synthesis: an overview. Comput Struct Biotechnol J 2012; 1:e201204002. [PMID: 24688632 PMCID: PMC3962216 DOI: 10.5936/csbj.201204002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 10/31/2011] [Accepted: 11/05/2011] [Indexed: 11/22/2022] Open
Abstract
Translation or protein synthesis consists of a complex system of chemical reactions, which ultimately result in decoding of the mRNA and the production of a protein. The complexity of this reaction system makes it difficult to quantitatively connect its input parameters (such as translation factor or ribosome concentrations, codon composition of the mRNA, or energy availability) to output parameters (such as protein synthesis rates or ribosome densities on mRNAs). Mathematical and computational models of translation have now been used for nearly five decades to investigate translation, and to shed light on the relationship between the different reactions in the system. This review gives an overview over the principal approaches used in the modelling efforts, and summarises some of the major findings that were made.
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Affiliation(s)
- Tobias von der Haar
- School of Biosciences and Kent Fungal Group, University of Kent, Canterbury, CT2 7NJ, UK
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36
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Sharma AK, Chowdhury D. Stochastic theory of protein synthesis and polysome: Ribosome profile on a single mRNA transcript. J Theor Biol 2011; 289:36-46. [DOI: 10.1016/j.jtbi.2011.08.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 12/31/2022]
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Brandt F, Carlson LA, Hartl FU, Baumeister W, Grünewald K. The Three-Dimensional Organization of Polyribosomes in Intact Human Cells. Mol Cell 2010; 39:560-9. [DOI: 10.1016/j.molcel.2010.08.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 02/10/2010] [Accepted: 08/05/2010] [Indexed: 12/29/2022]
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38
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Marcus A, Feeley J. Ribosome activation and polysome formation in vitro: requirement for ATP. Proc Natl Acad Sci U S A 2010; 56:1770-7. [PMID: 16591419 PMCID: PMC220176 DOI: 10.1073/pnas.56.6.1770] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- A Marcus
- AGRICULTURAL RESEARCH SERVICE, UNITED STATES DEPARTMENT OF AGRICULTURE, BELTSVILLE, MARYLAND
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Abstract
Mammalian erythrocytes are generally thought to lack RNA and therefore to be unable to translate new proteins in response to internal or external signals. Support for this long-standing view has accumulated from diverse studies, most of which have focused on the total content of RNA or the overall level of translation. However, more recent work on specific types of RNA has shown the presence in human erythrocytes of both Y RNA and microRNA. The latter seem particularly incongruous given that their normal role is to attenuate the translation of mRNA. Y RNA binds the Ro autoantigen which may have a role in cellular RNA quality control. Therefore the presence of both of these non-coding RNAs indicates the possible existence of other cryptic RNAs in erythrocytes. It also suggests either the existence of low levels of translation or new uncharacterized processes involving microRNA in these cells.
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Souquere S, Mollet S, Kress M, Dautry F, Pierron G, Weil D. Unravelling the ultrastructure of stress granules and associated P-bodies in human cells. J Cell Sci 2010; 122:3619-26. [PMID: 19812307 DOI: 10.1242/jcs.054437] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Stress granules are cytoplasmic ribonucleoprotein granules formed following various stresses that inhibit translation. They are thought to help protecting untranslated mRNAs until stress relief. Stress granules are frequently seen adjacent to P-bodies, which are involved in mRNA degradation and storage. We have previously shown in live cells that stress granule assembly often takes place in the vicinity of pre-existing P-bodies, suggesting that these two compartments are structurally related. Here we provide the first ultrastructural characterization of stress granules in eukaryotic cells by electron microscopy. Stress granules resulting from oxidative stress, heat-shock or protein overexpression are loosely organised fibrillo-granular aggregates of a moderate electron density, whereas P-bodies are denser and fibrillar. By in situ hybridization at the electron microscopic level, we show that stress granules are enriched in poly(A)(+) mRNAs, although these represent a minor fraction of the cellular mRNAs. Finally, we show that, despite close contact with P-bodies, both domains remain structurally distinct and do not interdigitate.
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41
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Kresge N, Simoni RD, Hill RL. The Discovery of Z-DNA: the Work of Alexander Rich. J Biol Chem 2009. [DOI: 10.1016/s0021-9258(20)37564-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Abstract
In the mid-1950s, RNA was a somewhat mysterious molecule with unknown three-dimensional structure and little hard evidence of biological function. Changes began with the 1956 discoveries of the RNA double helix and the phenomenon of nucleic acid hybridization. Discovery of the DNA-RNA hybrid helix in 1960 opened the door to understanding biological information transfer. Single-crystal X-ray diffraction analysis made it possible to precisely define the RNA double helix, discover the novel L-shaped fold of transfer RNA (tRNA), and finally reveal the complete three-dimensional tRNA structure by 1974. By then, a functional understanding of protein synthesis had developed with an appreciation of the various roles of different RNA species. This was the era of RNA awakening.
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Izak G, Lewis SM, Patterson MJ, Turpin F. Reticulocyte function in PNH: in vitro study of haemoglobin synthesis. SCANDINAVIAN JOURNAL OF HAEMATOLOGY 2009; 4:351-60. [PMID: 6081351 DOI: 10.1111/j.1600-0609.1967.tb01637.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Brandt F, Etchells SA, Ortiz JO, Elcock AH, Hartl FU, Baumeister W. The native 3D organization of bacterial polysomes. Cell 2009; 136:261-71. [PMID: 19167328 DOI: 10.1016/j.cell.2008.11.016] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 10/12/2008] [Accepted: 11/13/2008] [Indexed: 10/21/2022]
Abstract
Recent advances have led to insights into the structure of the bacterial ribosome, but little is known about the 3D organization of ribosomes in the context of translating polysomes. We employed cryoelectron tomography and a template-matching approach to map 70S ribosomes in vitrified bacterial translation extracts and in lysates of active E. coli spheroplasts. In these preparations, polysomal arrangements were observed in which neighboring ribosomes are densely packed and exhibit preferred orientations. Analysis of characteristic examples of polysomes reveals a staggered or pseudohelical organization of ribosomes along the mRNA trace, with the transcript being sequestered on the inside, the tRNA entrance sites being accessible, and the polypeptide exit sites facing the cytosol. Modeling of elongating nascent polypeptide chains suggests that this arrangement maximizes the distance between nascent chains on adjacent ribosomes, thereby reducing the probability of intermolecular interactions that would give rise to aggregation and limit productive folding.
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Affiliation(s)
- Florian Brandt
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany
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Kopeina GS, Afonina ZA, Gromova KV, Shirokov VA, Vasiliev VD, Spirin AS. Step-wise formation of eukaryotic double-row polyribosomes and circular translation of polysomal mRNA. Nucleic Acids Res 2008; 36:2476-88. [PMID: 18310103 PMCID: PMC2377419 DOI: 10.1093/nar/gkm1177] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The time course of polysome formation was studied in a long-term wheat germ cell-free translation system using sedimentation and electron microscopy techniques. The polysomes were formed on uncapped luciferase mRNA with translation-enhancing 5' and 3' UTRs. The formation of fully loaded polysomes was found to be a long process that required many rounds of translation and proceeded via several phases. First, short linear polysomes containing no more than six ribosomes were formed. Next, folding of these polysomes into short double-row clusters occurred. Subsequent gradual elongation of the clusters gave rise to heavy-loaded double-row strings containing up to 30-40 ribosomes. The formation of the double-row polysomes was considered to be equivalent to circularization of polysomes, with antiparallel halves of the circle being laterally stuck together by ribosome interactions. A slow exchange with free ribosomes and free mRNA observed in the double-row type polysomes, as well as the resistance of translation in them to AMP-PNP, provided evidence that most polysomal ribosomes reinitiate translation within the circularized polysomes without scanning of 5' UTR, while de novo initiation including 5' UTR scanning proceeds at a much slower rate. Removal or replacements of 5' and 3' UTRs affected the initial phase of translation, but did not prevent the formation of the double-row polysomes during translation.
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Affiliation(s)
- Gelina S Kopeina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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SORENSON GD. HEPATIC HEMATOCYTOPOIESIS IN THE FETAL RABBIT: A LIGHT AND ELECTRON MICROSCOPIC STUDY*. Ann N Y Acad Sci 2006; 111:45-69. [PMID: 14085869 DOI: 10.1111/j.1749-6632.1963.tb36948.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
I had the good luck to start research at the dawn of molecular biology when it was possible to ask fundamental questions about the nature of the nucleic acids and how information is transferred in living systems. The search for answers led me into many different areas, often with the question of how molecular structure leads to biological function. Early work in this period provided some of the roots supporting the current explosive developments in life sciences. Here I give a brief account of my development, describe some contributions, and provide a hint of the exhilaration in discovering new things. Most of all, I had the good fortune to have inspiring teachers, stimulating colleagues, and excellent students.
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Affiliation(s)
- Alexander Rich
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-430, USA
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Abstract
In most cases, translational control mechanisms result from the interaction of RNA-binding proteins with 5'- or 3'-untranslated regions (UTRs) of mRNA. In organisms ranging from viruses to humans, protein-mediated interactions between transcript termini result in the formation of an RNA loop. Such RNA 'circularization' is thought to increase translational efficiency and, in addition, permits regulation by novel mechanisms, particularly 3'-UTR-mediated translational control. Two general mechanisms of translational inhibition by 3'-UTR-binding proteins have been proposed, one in which mRNA closure is disrupted and another in which mRNA closure is required. Experimental evidence for the latter is provided by studies of interferon-gamma-mediated translational silencing of ceruloplasmin expression in monocytic cells. A multi-species analysis has shown that, in most vertebrates, 3'-UTRs are substantially longer than their 5' counterparts, indicating a significant potential for regulation. In addition, the average length of 3'-UTR sequences has increased during evolution, suggesting that their utilization might contribute to organism complexity.
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Affiliation(s)
- Barsanjit Mazumder
- Department of Cell Biology, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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