101
|
Aylett CHS, Ban N. Eukaryotic aspects of translation initiation brought into focus. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0186. [PMID: 28138072 DOI: 10.1098/rstb.2016.0186] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2016] [Indexed: 11/12/2022] Open
Abstract
In all organisms, mRNA-directed protein synthesis is catalysed by ribosomes. Although the basic aspects of translation are preserved in all kingdoms of life, important differences are found in the process of translation initiation, which is rate-limiting and the most important step for translation regulation. While great strides had been taken towards a complete structural understanding of the initiation of translation in eubacteria, our understanding of the eukaryotic process, which includes numerous eukaryotic-specific initiation factors, was until recently limited owing to a lack of structural information. In this review, we discuss recent results in the field that provide an increasingly complete molecular description of the eukaryotic initiation process. The structural snapshots obtained using a range of methods now provide insights into the architecture of the initiation complex, start-codon recognition by the initiator tRNA and the process of subunit joining. Future advances will require both higher-resolution insights into previously characterized complexes and mapping of initiation factors that control translation on an additional level by interacting only peripherally or transiently with ribosomal subunits.This article is part of the themed issue 'Perspectives on the ribosome'.
Collapse
Affiliation(s)
- Christopher H S Aylett
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| | - Nenad Ban
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| |
Collapse
|
102
|
Comparative Transcriptome Analysis Reveals Related Regulatory Mechanisms of Androgenic Gland in Eriocheir sinensis. BIOMED RESEARCH INTERNATIONAL 2017; 2017:4956216. [PMID: 29250542 PMCID: PMC5700504 DOI: 10.1155/2017/4956216] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/07/2017] [Accepted: 10/12/2017] [Indexed: 12/02/2022]
Abstract
Chinese mitten crab (Eriocheir sinensis) is one of the most commercially important aquaculture species in China. The androgenic gland (AG) of crustaceans plays pivotal roles in the regulation of male differentiation and in maintaining the male sexual characteristics. In order to reveal related mechanisms in AG, we compared transcriptomes of AG between proliferation and secretion phase. A total of 72,000 unigenes and 4,027 differentially expressed genes were obtained. Gene ontology enrichment analysis indicated that biological processes and metabolic pathways related to protein synthesis and secretion such as transcription, translation, and signal transduction were significantly enriched. Critical genes such as IAG, SXL, TRA-2, SRY, FTZ-F1, FOXL2, and FEM-1 were identified and potentially involved in maintaining the testis development and spermatogenesis. Ribosomes pathway revealed the cause of insulin-like androgenic gland hormone secretion increase. Three insulin-like receptors were thought to be associated with growth and spermatogenesis. In the neuroactive ligand-receptor interaction pathway, the expression of octopamine receptor, 5-HT receptor 1, and melatonin receptor was significantly changed, which revealed the key regulation mechanism of aggressive and mating behavior of males. Comparative transcriptome analysis provided new insights into the genome-wide molecular mechanisms of AG development and the regulatory mechanisms of male development.
Collapse
|
103
|
Chen W, Xie Z, Yang F, Ye K. Stepwise assembly of the earliest precursors of large ribosomal subunits in yeast. Nucleic Acids Res 2017; 45:6837-6847. [PMID: 28402444 PMCID: PMC5499802 DOI: 10.1093/nar/gkx254] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/04/2017] [Indexed: 12/15/2022] Open
Abstract
Small ribosomal subunits are co-transcriptionally assembled on the nascent precursor rRNA in Saccharomyces cerevisiae. It is unknown how the highly intertwined structure of 60S large ribosomal subunits is initially formed. Here, we affinity purified and analyzed a series of pre-60S particles assembled in vivo on plasmid-encoded pre-rRNA fragments of increasing lengths, revealing a spatiotemporal assembly map for 34 trans-acting assembly factors (AFs), 30 ribosomal proteins and 5S rRNA. The gradual association of AFs and ribosomal proteins with the pre-rRNA fragments strongly supports that the pre-60S is co-transcriptionally, rather than post-transcriptionally, assembled. The internal and external transcribed spacers ITS1, ITS2 and 3΄ ETS in pre-rRNA must be processed in pre-60S. We show that the processing machineries for ITS1 and ITS2 are primarily recruited by the 5΄ and 3΄ halves of pre-27S RNA, respectively. Nevertheless, processing of both ITS1 and ITS2 requires a complete 25S region. The 3΄ ETS plays a minor role in ribosome assembly, but is important for efficient rRNA processing and ribosome maturation. We also identified a distinct pre-60S state occurring before ITS2 processing. Our data reveal the elusive co-transcriptional assembly pathway of large ribosomal subunit.
Collapse
Affiliation(s)
- Wu Chen
- College of Biological Sciences, China Agricultural University, Beijing 100193, China.,National Institute of Biological Sciences, Beijing 102206, China.,Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhensheng Xie
- Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fuquan Yang
- Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
104
|
Structures of the human mitochondrial ribosome in native states of assembly. Nat Struct Mol Biol 2017; 24:866-869. [PMID: 28892042 DOI: 10.1038/nsmb.3464] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 08/15/2017] [Indexed: 12/11/2022]
Abstract
Mammalian mitochondrial ribosomes (mitoribosomes) have less rRNA content and 36 additional proteins compared with the evolutionarily related bacterial ribosome. These differences make the assembly of mitoribosomes more complex than the assembly of bacterial ribosomes, but the molecular details of mitoribosomal biogenesis remain elusive. Here, we report the structures of two late-stage assembly intermediates of the human mitoribosomal large subunit (mt-LSU) isolated from a native pool within a human cell line and solved by cryo-EM to ∼3-Å resolution. Comparison of the structures reveals insights into the timing of rRNA folding and protein incorporation during the final steps of ribosomal maturation and the evolutionary adaptations that are required to preserve biogenesis after the structural diversification of mitoribosomes. Furthermore, the structures redefine the ribosome silencing factor (RsfS) family as multifunctional biogenesis factors and identify two new assembly factors (L0R8F8 and mt-ACP) not previously implicated in mitoribosomal biogenesis.
Collapse
|
105
|
Two chaperones locked in an embrace: structure and function of the ribosome-associated complex RAC. Nat Struct Mol Biol 2017; 24:611-619. [PMID: 28771464 DOI: 10.1038/nsmb.3435] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/14/2017] [Indexed: 12/26/2022]
Abstract
Chaperones, which assist protein folding are essential components of every living cell. The yeast ribosome-associated complex (RAC) is a chaperone that is highly conserved in eukaryotic cells. The RAC consists of the J protein Zuo1 and the unconventional Hsp70 homolog Ssz1. The RAC heterodimer stimulates the ATPase activity of the ribosome-bound Hsp70 homolog Ssb, which interacts with nascent polypeptide chains to facilitate de novo protein folding. In addition, the RAC-Ssb system is required to maintain the fidelity of protein translation. Recent work reveals important details of the unique structures of RAC and Ssb and identifies how the chaperones interact with the ribosome. The new findings start to uncover how the exceptional chaperone triad cooperates in protein folding and maintenance of translational fidelity and its connection to extraribosomal functions.
Collapse
|
106
|
Patchett S, Musalgaonkar S, Malyutin AG, Johnson AW. The T-cell leukemia related rpl10-R98S mutant traps the 60S export adapter Nmd3 in the ribosomal P site in yeast. PLoS Genet 2017; 13:e1006894. [PMID: 28715419 PMCID: PMC5536393 DOI: 10.1371/journal.pgen.1006894] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 07/31/2017] [Accepted: 06/23/2017] [Indexed: 12/12/2022] Open
Abstract
Mutations in the ribosomal protein Rpl10 (uL16) can be drivers of T-cell acute lymphoblastic leukemia (T-ALL). We previously showed that these T-ALL mutations disrupt late cytoplasmic maturation of the 60S ribosomal subunit, blocking the release of the trans-acting factors Nmd3 and Tif6 in S. cerevisiae. Consequently, these mutant ribosomes do not efficiently pass the cytoplasmic quality control checkpoint and are blocked from engaging in translation. Here, we characterize suppressing mutations of the T-ALL-related rpl10-R98S mutant that bypass this block and show that the molecular defect of rpl10-R98S is a failure to release Nmd3 from the P site. Suppressing mutations were identified in Nmd3 and Tif6 that disrupted interactions between Nmd3 and the ribosome, or between Nmd3 and Tif6. Using an in vitro system with purified components, we found that Nmd3 inhibited Sdo1-stimulated Efl1 activity on mutant rpl10-R98S but not wild-type 60S subunits. Importantly, this inhibition was overcome in vitro by mutations in Nmd3 that suppressed rpl10-R98S in vivo. These results strongly support a model that Nmd3 must be dislodged from the P site to allow Sdo1 activation of Efl1, and define a failure in the removal of Nmd3 as the molecular defect of the T-ALL-associated rpl10-R98S mutation. The ribosome is a large and structurally complex macromolecular machine, responsible for synthesizing proteins in all living cells, across all domains of life. The correct assembly of ribosomes is important for their ability to faithfully decode messenger RNAs and synthesize proteins. The insertion of the ribosomal protein Rpl10 into the ribosome completes the catalytic center of the large subunit and is necessary for the removal of the assembly factors Nmd3 and Tif6, which allows the subunit to participate in translation. The insertion of Rpl10 is monitored by proteins that mimic translation factors during a quality control check for ribosome function. Ribosomes containing mutations in Rpl10 associated with pediatric T-cell leukemia fail in this quality control check and prevent the removal of Tif6 and Nmd3. However, it was not known how these mutations in Rpl10 block the quality control check. We recently presented the structure of Nmd3 and Tif6 on the large ribosomal subunit from yeast. In this work, we take advantage of our recent structural work and use a combination of genetic and biochemical techniques to delineate the molecular defect in the ribosome when Rpl10 is mutated.
Collapse
Affiliation(s)
- Stephanie Patchett
- Depatment of Molecular Biosciences, the University of Texas at Austin, Austin, Texas, United States of America
| | - Sharmishtha Musalgaonkar
- Depatment of Molecular Biosciences, the University of Texas at Austin, Austin, Texas, United States of America
| | - Andrey G Malyutin
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York, United States of America
| | - Arlen W Johnson
- Depatment of Molecular Biosciences, the University of Texas at Austin, Austin, Texas, United States of America
| |
Collapse
|
107
|
Current Nucleic Acid Extraction Methods and Their Implications to Point-of-Care Diagnostics. BIOMED RESEARCH INTERNATIONAL 2017; 2017:9306564. [PMID: 28785592 PMCID: PMC5529626 DOI: 10.1155/2017/9306564] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/05/2017] [Indexed: 12/12/2022]
Abstract
Nucleic acid extraction (NAE) plays a vital role in molecular biology as the primary step for many downstream applications. Many modifications have been introduced to the original 1869 method. Modern processes are categorized into chemical or mechanical, each with peculiarities that influence their use, especially in point-of-care diagnostics (POC-Dx). POC-Dx is a new approach aiming to replace sophisticated analytical machinery with microanalytical systems, able to be used near the patient, at the point of care or point of need. Although notable efforts have been made, a simple and effective extraction method is still a major challenge for widespread use of POC-Dx. In this review, we dissected the working principle of each of the most common NAE methods, overviewing their advantages and disadvantages, as well their potential for integration in POC-Dx systems. At present, it seems difficult, if not impossible, to establish a procedure which can be universally applied to POC-Dx. We also discuss the effects of the NAE chemicals upon the main plastic polymers used to mass produce POC-Dx systems. We end our review discussing the limitations and challenges that should guide the quest for an efficient extraction method that can be integrated in a POC-Dx system.
Collapse
|
108
|
Ali MU, Ur Rahman MS, Jia Z, Jiang C. Eukaryotic translation initiation factors and cancer. Tumour Biol 2017; 39:1010428317709805. [PMID: 28653885 DOI: 10.1177/1010428317709805] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.
Collapse
Affiliation(s)
- Muhammad Umar Ali
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Muhammad Saif Ur Rahman
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhenyu Jia
- 2 Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, China
| | - Cao Jiang
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
109
|
Espinar-Marchena FJ, Babiano R, Cruz J. Placeholder factors in ribosome biogenesis: please, pave my way. MICROBIAL CELL 2017; 4:144-168. [PMID: 28685141 PMCID: PMC5425277 DOI: 10.15698/mic2017.05.572] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The synthesis of cytoplasmic eukaryotic ribosomes is an extraordinarily energy-demanding cellular activity that occurs progressively from the nucleolus to the cytoplasm. In the nucleolus, precursor rRNAs associate with a myriad of trans-acting factors and some ribosomal proteins to form pre-ribosomal particles. These factors include snoRNPs, nucleases, ATPases, GTPases, RNA helicases, and a vast list of proteins with no predicted enzymatic activity. Their coordinate activity orchestrates in a spatiotemporal manner the modification and processing of precursor rRNAs, the rearrangement reactions required for the formation of productive RNA folding intermediates, the ordered assembly of the ribosomal proteins, and the export of pre-ribosomal particles to the cytoplasm; thus, providing speed, directionality and accuracy to the overall process of formation of translation-competent ribosomes. Here, we review a particular class of trans-acting factors known as "placeholders". Placeholder factors temporarily bind selected ribosomal sites until these have achieved a structural context that is appropriate for exchanging the placeholder with another site-specific binding factor. By this strategy, placeholders sterically prevent premature recruitment of subsequently binding factors, premature formation of structures, avoid possible folding traps, and act as molecular clocks that supervise the correct progression of pre-ribosomal particles into functional ribosomal subunits. We summarize the current understanding of those factors that delay the assembly of distinct ribosomal proteins or subsequently bind key sites in pre-ribosomal particles. We also discuss recurrent examples of RNA-protein and protein-protein mimicry between rRNAs and/or factors, which have clear functional implications for the ribosome biogenesis pathway.
Collapse
Affiliation(s)
- Francisco J Espinar-Marchena
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| | - Reyes Babiano
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain.,Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| | - Jesús Cruz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| |
Collapse
|
110
|
Malyutin AG, Musalgaonkar S, Patchett S, Frank J, Johnson AW. Nmd3 is a structural mimic of eIF5A, and activates the cpGTPase Lsg1 during 60S ribosome biogenesis. EMBO J 2017; 36:854-868. [PMID: 28179369 PMCID: PMC5376978 DOI: 10.15252/embj.201696012] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 12/22/2022] Open
Abstract
During ribosome biogenesis in eukaryotes, nascent subunits are exported to the cytoplasm in a functionally inactive state. 60S subunits are activated through a series of cytoplasmic maturation events. The last known events in the cytoplasm are the release of Tif6 by Efl1 and Sdo1 and the release of the export adapter, Nmd3, by the GTPase Lsg1. Here, we have used cryo-electron microscopy to determine the structure of the 60S subunit bound by Nmd3, Lsg1, and Tif6. We find that a central domain of Nmd3 mimics the translation elongation factor eIF5A, inserting into the E site of the ribosome and pulling the L1 stalk into a closed position. Additional domains occupy the P site and extend toward the sarcin-ricin loop to interact with Tif6. Nmd3 and Lsg1 together embrace helix 69 of the B2a intersubunit bridge, inducing base flipping that we suggest may activate the GTPase activity of Lsg1.
Collapse
Affiliation(s)
- Andrey G Malyutin
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | | | - Stephanie Patchett
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
- Department of Biological Sciences, Columbia University, New York, NY, USA
- Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Arlen W Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA
| |
Collapse
|
111
|
Nielsen MH, Flygaard RK, Jenner LB. Structural analysis of ribosomal RACK1 and its role in translational control. Cell Signal 2017; 35:272-281. [PMID: 28161490 DOI: 10.1016/j.cellsig.2017.01.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 12/28/2022]
Abstract
Receptor for Activated C-Kinase 1 (RACK1) belongs to the WD40 family of proteins, known to act as scaffolding proteins in interaction networks. Accordingly, RACK1 is found to have numerous interacting partners ranging from kinases and signaling proteins to membrane bound receptors and ion channels. Interestingly, RACK1 has also been identified as a ribosomal protein present in all eukaryotic ribosomes. Structures of eukaryotic ribosomes have shown RACK1 to be located at the back of the head of the small ribosomal subunit. This suggests that RACK1 could act as a ribosomal scaffolding protein recruiting regulators of translation to the ribosome, and several studies have in fact found RACK1 to play a role in regulation of translation. To fully understand the role of RACK1 we need to understand whether the many reported interaction partners of RACK1 bind to free or ribosomal RACK1. In this review we provide a structural analysis of ribosome-bound RACK1 to provide a basis for answering this fundamental question. Our analysis shows that RACK1 is tightly bound to the ribosome through highly conserved and specific interactions confirming RACK1 as an integral ribosomal protein. Furthermore, we have analyzed whether reported binding sites for RACK1 interacting partners with a proposed role in translational control are accessible on ribosomal RACK1. Our analysis shows that most of the interaction partners with putative regulatory functions have binding sites that are available on ribosomal RACK1, supporting the role of RACK1 as a ribosomal signaling hub. We also discuss the possible role for RACK1 in recruitment of ribosomes to focal adhesion sites and regulation of local translation during cell spreading and migration.
Collapse
Affiliation(s)
- Maja Holch Nielsen
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| | - Rasmus Kock Flygaard
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| | - Lasse Bohl Jenner
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| |
Collapse
|
112
|
Structural snapshot of cytoplasmic pre-60S ribosomal particles bound by Nmd3, Lsg1, Tif6 and Reh1. Nat Struct Mol Biol 2017; 24:214-220. [PMID: 28112732 DOI: 10.1038/nsmb.3364] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 12/19/2016] [Indexed: 01/01/2023]
Abstract
A key step in ribosome biogenesis is the nuclear export of pre-ribosomal particles. Nmd3, a highly conserved protein in eukaryotes, is a specific adaptor required for the export of pre-60S particles. Here we used cryo-electron microscopy (cryo-EM) to characterize Saccharomyces cerevisiae pre-60S particles purified with epitope-tagged Nmd3. Our structural analysis indicates that these particles belong to a specific late stage of cytoplasmic pre-60S maturation in which ribosomal proteins uL16, uL10, uL11, eL40 and eL41 are deficient, but ribosome assembly factors Nmd3, Lsg1, Tif6 and Reh1 are present. Nmd3 and Lsg1 are located near the peptidyl-transferase center (PTC). In particular, Nmd3 recognizes the PTC in its near-mature conformation. In contrast, Reh1 is anchored to the exit of the polypeptide tunnel, with its C terminus inserted into the tunnel. These findings pinpoint a structural checkpoint role for Nmd3 in PTC assembly, and provide information about functional and mechanistic roles of these assembly factors in the maturation of the 60S ribosomal subunit.
Collapse
|
113
|
Yang QQ, Yang SS, Tan JL, Luo GX, He WF, Wu J. Process of Hypertrophic Scar Formation: Expression of Eukaryotic Initiation Factor 6. Chin Med J (Engl) 2016; 128:2787-91. [PMID: 26481747 PMCID: PMC4736889 DOI: 10.4103/0366-6999.167359] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Hypertrophic scar is one of the most common complications and often causes the disfigurement or deformity in burn or trauma patients. Therapeutic methods on hypertrophic scar treatment have limitations due to the poor understanding of mechanisms of hypertrophic scar formation. To throw light on the molecular mechanism of hypertrophic scar formation will definitely improve the outcome of the treatment. This study aimed to illustrate the negative role of eukaryotic initiation factor 6 (eIF6) in the process of human hypertrophic scar formation, and provide a possible indicator of hypertrophic scar treatment and a potential target molecule for hypertrophic scar. Methods: In the present study, we investigated the protein expression of eIF6 in the human hypertrophic scar of different periods by immunohistochemistry and Western blot analysis. Results: In the hypertrophic scar tissue, eIF6 expression was significantly decreased and absent in the basal layer of epidermis in the early period, and increased slowly and began to appear in the basal layer of epidermis by the scar formation time. Conclusions: This study confirmed that eIF6 expression was significantly related to the development of hypertrophic scar, and the eIF6 may be a target molecule for hypertrophic scar control or could be an indicator of the outcomes for other treatment modalities.
Collapse
Affiliation(s)
| | | | | | | | | | - Jun Wu
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038; Chongqing Key Laboratory for Disease Proteomics, The Third Military Medical University, Chongqing 400038, China
| |
Collapse
|
114
|
Peña C, Schütz S, Fischer U, Chang Y, Panse VG. Prefabrication of a ribosomal protein subcomplex essential for eukaryotic ribosome formation. eLife 2016; 5. [PMID: 27929371 PMCID: PMC5148605 DOI: 10.7554/elife.21755] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/29/2016] [Indexed: 01/21/2023] Open
Abstract
Spatial clustering of ribosomal proteins (r-proteins) through tertiary interactions is a striking structural feature of the eukaryotic ribosome. However, the functional importance of these intricate inter-connections, and how they are established is currently unclear. Here, we reveal that a conserved ATPase, Fap7, organizes interactions between neighboring r-proteins uS11 and eS26 prior to their delivery to the earliest ribosome precursor, the 90S. In vitro, uS11 only when bound to Fap7 becomes competent to recruit eS26 through tertiary contacts found between these r-proteins on the mature ribosome. Subsequently, Fap7 ATPase activity unloads the uS11:eS26 subcomplex onto its rRNA binding site, and therefore ensures stoichiometric integration of these r-proteins into the 90S. Fap7-depletion in vivo renders uS11 susceptible to proteolysis, and precludes eS26 incorporation into the 90S. Thus, prefabrication of a native-like r-protein subcomplex drives efficient and accurate construction of the eukaryotic ribosome. DOI:http://dx.doi.org/10.7554/eLife.21755.001
Collapse
Affiliation(s)
- Cohue Peña
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Sabina Schütz
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Ute Fischer
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Yiming Chang
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Vikram G Panse
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| |
Collapse
|
115
|
Ting YH, Lu TJ, Johnson AW, Shie JT, Chen BR, Kumar S S, Lo KY. Bcp1 Is the Nuclear Chaperone of Rpl23 in Saccharomyces cerevisiae. J Biol Chem 2016; 292:585-596. [PMID: 27913624 DOI: 10.1074/jbc.m116.747634] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 11/21/2016] [Indexed: 12/18/2022] Open
Abstract
Eukaryotic ribosomes are composed of rRNAs and ribosomal proteins. Ribosomal proteins are translated in the cytoplasm and imported into the nucleus for assembly with the rRNAs. It has been shown that chaperones or karyopherins responsible for import can maintain the stability of ribosomal proteins by neutralizing unfavorable positive charges and thus facilitate their transports. Among 79 ribosomal proteins in yeast, only a few are identified with specific chaperones. Besides the classic role in maintaining protein stability, chaperones have additional roles in transport, chaperoning the assembly site, and dissociation of ribosomal proteins from karyopherins. Bcp1 has been shown to be necessary for the export of Mss4, a phosphatidylinositol 4-phosphate 5-kinase, and required for ribosome biogenesis. However, its specific function in ribosome biogenesis has not been described. Here, we show that Bcp1 dissociates Rpl23 from the karyopherins and associates with Rpl23 afterward. Loss of Bcp1 causes instability of Rpl23 and deficiency of 60S subunits. In summary, Bcp1 is a novel 60S biogenesis factor via chaperoning Rpl23 in the nucleus.
Collapse
Affiliation(s)
- Ya-Han Ting
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Ting-Jun Lu
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Arlen W Johnson
- the Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, and
| | - Jing-Ting Shie
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Bo-Ru Chen
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Suresh Kumar S
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan.,the Department of Medical Microbiology and Parasitology, Universiti Putra Malaysia, 43400 Selangor, Malaysia
| | - Kai-Yin Lo
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan,
| |
Collapse
|
116
|
Cavadas C, Aveleira CA, Souza GFP, Velloso LA. The pathophysiology of defective proteostasis in the hypothalamus - from obesity to ageing. Nat Rev Endocrinol 2016; 12:723-733. [PMID: 27388987 DOI: 10.1038/nrendo.2016.107] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Hypothalamic dysfunction has emerged as an important mechanism involved in the development of obesity and its comorbidities, as well as in the process of ageing and age-related diseases, such as type 2 diabetes mellitus, hypertension and Alzheimer disease. In both obesity and ageing, inflammatory signalling is thought to coordinate many of the cellular events that lead to hypothalamic neuronal dysfunction. This process is triggered by the activation of signalling via the toll-like receptor 4 pathway and endoplasmic reticulum stress, which in turn results in intracellular inflammatory signalling. However, the process that connects inflammation with neuronal dysfunction is complex and includes several regulatory mechanisms that ultimately control the homeostasis of intracellular proteins and organelles (also known as 'proteostasis'). This Review discusses the evidence for the key role of proteostasis in the control of hypothalamic neurons and the involvement of this process in regulating whole-body energy homeostasis and lifespan.
Collapse
Affiliation(s)
- Cláudia Cavadas
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
- Faculty of Pharmacy, University of Coimbra, Coimbra, 3004-504, Portugal
| | - Célia A Aveleira
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
| | - Gabriela F P Souza
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Campinas, 1308-970, Brazil
| | - Lício A Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Campinas, 1308-970, Brazil
| |
Collapse
|
117
|
Pillet B, Mitterer V, Kressler D, Pertschy B. Hold on to your friends: Dedicated chaperones of ribosomal proteins: Dedicated chaperones mediate the safe transfer of ribosomal proteins to their site of pre-ribosome incorporation. Bioessays 2016; 39:1-12. [PMID: 27859409 DOI: 10.1002/bies.201600153] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Eukaryotic ribosomes are assembled from their components, the ribosomal RNAs and ribosomal proteins, in a tremendously complex, multi-step process, which primarily takes place in the nuclear compartment. Therefore, most ribosomal proteins have to travel from the cytoplasm to their incorporation site on pre-ribosomes within the nucleus. However, due to their particular characteristics, such as a highly basic amino acid composition and the presence of unstructured extensions, ribosomal proteins are especially prone to aggregation and degradation in their unassembled state, hence specific mechanisms must operate to ensure their safe delivery. Recent studies have uncovered a group of proteins, termed dedicated chaperones, specialized in accompanying and guarding individual ribosomal proteins. In this essay, we review how these dedicated chaperones utilize different folds to interact with their ribosomal protein clients and how they ensure their soluble expression and interconnect their intracellular transport with their efficient assembly into pre-ribosomes.
Collapse
Affiliation(s)
- Benjamin Pillet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Valentin Mitterer
- Institut für Molekulare Biowissenschaften, Universität Graz, Graz, Austria
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Brigitte Pertschy
- Institut für Molekulare Biowissenschaften, Universität Graz, Graz, Austria
| |
Collapse
|
118
|
Greber BJ. Mechanistic insight into eukaryotic 60S ribosomal subunit biogenesis by cryo-electron microscopy. RNA (NEW YORK, N.Y.) 2016; 22:1643-1662. [PMID: 27875256 PMCID: PMC5066618 DOI: 10.1261/rna.057927.116] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Eukaryotic ribosomes, the protein-producing factories of the cell, are composed of four ribosomal RNA molecules and roughly 80 proteins. Their biogenesis is a complex process that involves more than 200 biogenesis factors that facilitate the production, modification, and assembly of ribosomal components and the structural transitions along the maturation pathways of the pre-ribosomal particles. Here, I review recent structural and mechanistic insights into the biogenesis of the large ribosomal subunit that were furthered by cryo-electron microscopy of natively purified pre-60S particles and in vitro reconstituted ribosome assembly factor complexes. Combined with biochemical, genetic, and previous structural data, these structures have provided detailed insights into the assembly and maturation of the central protuberance of the 60S subunit, the network of biogenesis factors near the ribosomal tunnel exit, and the functional activation of the large ribosomal subunit during cytoplasmic maturation.
Collapse
Affiliation(s)
- Basil J Greber
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720-3220, USA
| |
Collapse
|
119
|
Wu S, Tan D, Woolford JL, Dong MQ, Gao N. Atomic modeling of the ITS2 ribosome assembly subcomplex from cryo-EM together with mass spectrometry-identified protein-protein crosslinks. Protein Sci 2016; 26:103-112. [PMID: 27643814 DOI: 10.1002/pro.3045] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 12/17/2022]
Abstract
The assembly of ribosomal subunits starts in the nucleus, initiated by co-transcriptional folding of nascent ribosomal RNA (rRNA) transcripts and binding of ribosomal proteins and assembly factors. The internal transcribed spacer 2 (ITS2) is a precursor sequence to be processed from the intermediate 27S rRNA in the nucleoplasm; its removal is required for nuclear export of pre-60S particles. The proper processing of the ITS2 depends on multiple associated assembly factors and RNases. However, none of the structures of the known ITS2-binding factors is available. Here, we describe the modeling of the ITS2 subcomplex, including five assembly factors Cic1, Nop7, Nop15, Nop53, and Rlp7, using a combination of cryo-electron microscopy and cross-linking of proteins coupled with mass spectrometry approaches. The resulting atomic models provide structural insights into their function in ribosome assembly, and establish a framework for further dissection of their molecular roles in ITS2 processing.
Collapse
Affiliation(s)
- Shan Wu
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Dan Tan
- National Institute of Biological Sciences, Beijing, 102206, People's Republic of China
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, 15213
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, 102206, People's Republic of China
| | - Ning Gao
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, People's Republic of China
| |
Collapse
|
120
|
Tutuncuoglu B, Jakovljevic J, Wu S, Gao N, Woolford JL. The N-terminal extension of yeast ribosomal protein L8 is involved in two major remodeling events during late nuclear stages of 60S ribosomal subunit assembly. RNA (NEW YORK, N.Y.) 2016; 22:1386-1399. [PMID: 27390266 PMCID: PMC4986894 DOI: 10.1261/rna.055798.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/24/2016] [Indexed: 06/01/2023]
Abstract
Assaying effects on pre-rRNA processing and ribosome assembly upon depleting individual ribosomal proteins (r-proteins) provided an initial paradigm for assembly of eukaryotic ribosomes in vivo-that each structural domain of ribosomal subunits assembles in a hierarchical fashion. However, two features suggest that a more complex pathway may exist: (i) Some r-proteins contain extensions that reach long distances across ribosomes to interact with multiple rRNA domains as well as with other r-proteins. (ii) Individual r-proteins may assemble in a stepwise fashion. For example, the globular domain of an r-protein might assemble separately from its extensions. Thus, these extensions might play roles in assembly that could not be revealed by depleting the entire protein. Here, we show that deleting or mutating extensions of r-proteins L7 (uL30) and L35 (uL29) from yeast reveal important roles in early and middle steps during 60S ribosomal subunit biogenesis. Detailed analysis of the N-terminal terminal extension of L8 (eL8) showed that it is necessary for late nuclear stages of 60S subunit assembly involving two major remodeling events: removal of the ITS2 spacer; and reorganization of the central protuberance (CP) containing 5S rRNA and r-proteins L5 (uL18) and L11 (uL5). Mutations in the L8 extension block processing of 7S pre-rRNA, prevent release of assembly factors Rpf2 and Rrs1 from pre-ribosomes, which is required for rotation of the CP, and block association of Sda1, the Rix1 complex, and the Rea1 ATPase involved in late steps of remodeling.
Collapse
Affiliation(s)
- Beril Tutuncuoglu
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Jelena Jakovljevic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Shan Wu
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ning Gao
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| |
Collapse
|
121
|
Smethurst DGJ, Cooper KF. ER fatalities-The role of ER-mitochondrial contact sites in yeast life and death decisions. Mech Ageing Dev 2016; 161:225-233. [PMID: 27507669 DOI: 10.1016/j.mad.2016.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 06/22/2016] [Accepted: 07/19/2016] [Indexed: 12/22/2022]
Abstract
Following extracellular stress signals, all eukaryotic cells choose whether to elicit a pro-survival or pro-death response. The decision over which path to take is governed by the severity and duration of the damage. In response to mild stress, pro-survival programs are initiated (unfolded protein response, autophagy, mitophagy) whereas severe or chronic stress forces the cell to abandon these adaptive programs and shift towards regulated cell death to remove irreversibly damaged cells. Both pro-survival and pro-death programs involve regulated communication between the endoplasmic reticulum (ER) and mitochondria. In yeast, recent data suggest this inter-organelle contact is facilitated by the endoplasmic reticulum mitochondria encounter structure (ERMES). These membrane contacts are not only important for the exchange of cellular signals, but also play a role in mitochondrial tethering during mitophagy, mitochondrial fission and mitochondrial inheritance. This review focuses on recent findings in yeast that shed light on how ER-mitochondrial communication mediates critical cell fate decisions.
Collapse
Affiliation(s)
- Daniel G J Smethurst
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, 08055 USA
| | - Katrina F Cooper
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, 08055 USA.
| |
Collapse
|
122
|
Kim SJ, Strich R. Rpl22 is required for IME1 mRNA translation and meiotic induction in S. cerevisiae. Cell Div 2016; 11:10. [PMID: 27478489 PMCID: PMC4966820 DOI: 10.1186/s13008-016-0024-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/08/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The transition from mitotic cell division to meiotic development in S. cerevisiae requires induction of a transient transcription program that is initiated by Ime1-dependent destruction of the repressor Ume6. Although IME1 mRNA is observed in vegetative cultures, Ime1 protein is not suggesting the presence of a regulatory system restricting translation to meiotic cells. RESULTS This study demonstrates that IME1 mRNA translation requires Rpl22A and Rpl22B, eukaryotic-specific ribosomal protein paralogs of the 60S large subunit. In the absence of Rpl22 function, IME1 mRNA synthesis is normal in cultures induced to enter meiosis. However, Ime1 protein production is reduced and the Ume6 repressor is not destroyed in rpl22 mutant cells preventing early meiotic gene induction resulting in a pre-meiosis I arrest. This role for Rpl22 is not a general consequence of mutating non-essential large ribosomal proteins as strains lacking Rpl29 or Rpl39 execute meiosis with nearly wild-type efficiencies. Several results indicate that Rpl22 functions by enhancing IME1 mRNA translation. First, the Ime1 protein synthesized in rpl22 mutant cells demonstrates the same turnover rate as in wild-type cultures. In addition, IME1 transcript is found in polysome fractions isolated from rpl22 mutant cells indicating that mRNA nuclear export and ribosome association occurs. Finally, deleting the unusually long 5'UTR restores Ime1 levels and early meiotic gene transcription in rpl22 mutants suggesting that Rpl22 enhances translation through this element. Polysome profiles revealed that under conditions of high translational output, Rpl22 maintains high free 60S subunit levels thus preventing halfmer formation, a translation species indicative of mRNAs bound by an unpaired 40S subunit. In addition to meiosis, Rpl22 is also required for invasive and pseudohyphal growth. CONCLUSIONS These findings indicate that Rpl22A and Rpl22B are required to selectively translate IME1 mRNA that is required for meiotic induction and subsequent gametogenesis. In addition, our results imply a more general role for Rpl22 in cell fate switches responding to environmental nitrogen signals.
Collapse
Affiliation(s)
- Stephen J Kim
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Two Medical Center Dr., Stratford, NJ 08055 USA
| | - Randy Strich
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Two Medical Center Dr., Stratford, NJ 08055 USA
| |
Collapse
|
123
|
Use of evolutionary information in the fitting of atomic level protein models in low resolution cryo-EM map of a protein assembly improves the accuracy of the fitting. J Struct Biol 2016; 195:294-305. [PMID: 27444391 DOI: 10.1016/j.jsb.2016.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 07/15/2016] [Accepted: 07/18/2016] [Indexed: 11/22/2022]
Abstract
Protein-protein interface residues, especially those at the core of the interface, exhibit higher conservation than residues in solvent exposed regions. Here, we explore the ability of this differential conservation to evaluate fittings of atomic models in low-resolution cryo-EM maps and select models from the ensemble of solutions that are often proposed by different model fitting techniques. As a prelude, using a non-redundant and high-resolution structural dataset involving 125 permanent and 95 transient complexes, we confirm that core interface residues are conserved significantly better than nearby non-interface residues and this result is used in the cryo-EM map analysis. From the analysis of inter-component interfaces in a set of fitted models associated with low-resolution cryo-EM maps of ribosomes, chaperones and proteasomes we note that a few poorly conserved residues occur at interfaces. Interestingly a few conserved residues are not in the interface, though they are close to the interface. These observations raise the potential requirement of refitting the models in the cryo-EM maps. We show that sampling an ensemble of models and selection of models with high residue conservation at the interface and in good agreement with the density helps in improving the accuracy of the fit. This study indicates that evolutionary information can serve as an additional input to improve and validate fitting of atomic models in cryo-EM density maps.
Collapse
|
124
|
Espinar-Marchena FJ, Fernández-Fernández J, Rodríguez-Galán O, Fernández-Pevida A, Babiano R, de la Cruz J. Role of the yeast ribosomal protein L16 in ribosome biogenesis. FEBS J 2016; 283:2968-85. [PMID: 27374275 DOI: 10.1111/febs.13797] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/02/2016] [Accepted: 06/29/2016] [Indexed: 10/21/2022]
Abstract
Most ribosomal proteins play essential roles in ribosome synthesis and function. In this study, we have analysed the contribution of yeast ribosomal protein L16 to ribosome biogenesis. We show that in vivo depletion of the essential L16 protein results in a deficit in 60S subunits and the appearance of half-mer polysomes. This phenotype is likely due to the instability and rapid turnover of early and intermediate pre-60S particles, as evidenced by the reduced steady-state levels of 27SBS and 7SL /S pre-rRNA, and the low amounts of de novo synthesized 27S pre-rRNA and 25S rRNA. Additionally, depletion of L16 blocks nucleocytoplasmic export of pre-60S particles. Moreover, we show that L16 assembles in the nucleolus and binds to early 90S preribosomal particles. Many evolutionarily conserved ribosomal proteins possess extra eukaryote-specific amino- or carboxy-terminal extensions and/or internal loops. Here, we have also investigated the role of the eukaryote-specific carboxy-terminal extension of L16. Progressive truncation of this extension recapitulates, albeit to a lesser extent, the growth and ribosome biogenesis defects of the L16 depletion. We conclude that L16 assembly is a prerequisite to properly stabilize rRNA structures within early pre-60S particles, thereby favouring efficient 27S pre-rRNA processing within the internal transcribed spacer 1 at sites A3 and B1 . Upon depletion of L16, the lack of this stabilization aborts early pre-60S particle assembly and subjects these intermediates to turnover.
Collapse
Affiliation(s)
- Francisco J Espinar-Marchena
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Genética, Universidad de Sevilla, Spain
| | - José Fernández-Fernández
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Genética, Universidad de Sevilla, Spain
| | - Olga Rodríguez-Galán
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Genética, Universidad de Sevilla, Spain
| | - Antonio Fernández-Pevida
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Genética, Universidad de Sevilla, Spain
| | - Reyes Babiano
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Genética, Universidad de Sevilla, Spain
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Genética, Universidad de Sevilla, Spain
| |
Collapse
|
125
|
Hunziker M, Barandun J, Petfalski E, Tan D, Delan-Forino C, Molloy KR, Kim KH, Dunn-Davies H, Shi Y, Chaker-Margot M, Chait BT, Walz T, Tollervey D, Klinge S. UtpA and UtpB chaperone nascent pre-ribosomal RNA and U3 snoRNA to initiate eukaryotic ribosome assembly. Nat Commun 2016; 7:12090. [PMID: 27354316 PMCID: PMC4931317 DOI: 10.1038/ncomms12090] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 05/27/2016] [Indexed: 01/14/2023] Open
Abstract
Early eukaryotic ribosome biogenesis involves large multi-protein complexes, which co-transcriptionally associate with pre-ribosomal RNA to form the small subunit processome. The precise mechanisms by which two of the largest multi-protein complexes—UtpA and UtpB—interact with nascent pre-ribosomal RNA are poorly understood. Here, we combined biochemical and structural biology approaches with ensembles of RNA–protein cross-linking data to elucidate the essential functions of both complexes. We show that UtpA contains a large composite RNA-binding site and captures the 5′ end of pre-ribosomal RNA. UtpB forms an extended structure that binds early pre-ribosomal intermediates in close proximity to architectural sites such as an RNA duplex formed by the 5′ ETS and U3 snoRNA as well as the 3′ boundary of the 18S rRNA. Both complexes therefore act as vital RNA chaperones to initiate eukaryotic ribosome assembly. Eukaryotic ribosome biogenesis involves a large number of maturations factors which are responsible for the stepwise assembly of the ribosomal subunits. Here the authors use an array of biochemical and structural biology methods to investigate the function of the UtpA and UtpB complexes as part of the small subunit processome.
Collapse
Affiliation(s)
- Mirjam Hunziker
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Jonas Barandun
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Elisabeth Petfalski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Dongyan Tan
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Clémentine Delan-Forino
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Kelly R Molloy
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Kelly H Kim
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, New York 10065, USA
| | - Hywel Dunn-Davies
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Yi Shi
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Malik Chaker-Margot
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA.,Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, New York, New York 10065, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, New York 10065, USA
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Sebastian Klinge
- Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York 10065, USA
| |
Collapse
|
126
|
Lawrence MG, Shamsuzzaman M, Kondopaka M, Pascual C, Zengel JM, Lindahl L. The extended loops of ribosomal proteins uL4 and uL22 of Escherichia coli contribute to ribosome assembly and protein translation. Nucleic Acids Res 2016; 44:5798-810. [PMID: 27257065 PMCID: PMC4937340 DOI: 10.1093/nar/gkw493] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 05/21/2016] [Indexed: 11/13/2022] Open
Abstract
Nearly half of ribosomal proteins are composed of a domain on the ribosome surface and a loop or extension that penetrates into the organelle's RNA core. Our previous work showed that ribosomes lacking the loops of ribosomal proteins uL4 or uL22 are still capable of entering polysomes. However, in those experiments we could not address the formation of mutant ribosomes, because we used strains that also expressed wild-type uL4 and uL22. Here, we have focused on ribosome assembly and function in strains in which loop deletion mutant genes are the only sources of uL4 or uL22 protein. The uL4 and uL22 loop deletions have different effects, but both mutations result in accumulation of immature particles that do not accumulate in detectable amounts in wild-type strains. Thus, our results suggest that deleting the loops creates kinetic barriers in the normal assembly pathway, possibly resulting in assembly via alternate pathway(s). Furthermore, deletion of the uL4 loop results in cold-sensitive ribosome assembly and function. Finally, ribosomes carrying either of the loop-deleted proteins responded normally to the secM translation pausing peptide, but the uL4 mutant responded very inefficiently to the cmlAcrb pause peptide.
Collapse
Affiliation(s)
- Marlon G Lawrence
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Md Shamsuzzaman
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Maithri Kondopaka
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Clarence Pascual
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Janice M Zengel
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Lasse Lindahl
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| |
Collapse
|
127
|
Diverse roles of assembly factors revealed by structures of late nuclear pre-60S ribosomes. Nature 2016; 534:133-7. [PMID: 27251291 DOI: 10.1038/nature17942] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 03/21/2016] [Indexed: 01/03/2023]
Abstract
Ribosome biogenesis is a highly complex process in eukaryotes, involving temporally and spatially regulated ribosomal protein (r-protein) binding and ribosomal RNA remodelling events in the nucleolus, nucleoplasm and cytoplasm. Hundreds of assembly factors, organized into sequential functional groups, facilitate and guide the maturation process into productive assembly branches in and across different cellular compartments. However, the precise mechanisms by which these assembly factors function are largely unknown. Here we use cryo-electron microscopy to characterize the structures of yeast nucleoplasmic pre-60S particles affinity-purified using the epitope-tagged assembly factor Nog2. Our data pinpoint the locations and determine the structures of over 20 assembly factors, which are enriched in two areas: an arc region extending from the central protuberance to the polypeptide tunnel exit, and the domain including the internal transcribed spacer 2 (ITS2) that separates 5.8S and 25S ribosomal RNAs. In particular, two regulatory GTPases, Nog2 and Nog1, act as hub proteins to interact with multiple, distant assembly factors and functional ribosomal RNA elements, manifesting their critical roles in structural remodelling checkpoints and nuclear export. Moreover, our snapshots of compositionally and structurally different pre-60S intermediates provide essential mechanistic details for three major remodelling events before nuclear export: rotation of the 5S ribonucleoprotein, construction of the active centre and ITS2 removal. The rich structural information in our structures provides a framework to dissect molecular roles of diverse assembly factors in eukaryotic ribosome assembly.
Collapse
|
128
|
Voorhees RM, Hegde RS. Toward a structural understanding of co-translational protein translocation. Curr Opin Cell Biol 2016; 41:91-9. [PMID: 27155805 DOI: 10.1016/j.ceb.2016.04.009] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 01/06/2023]
Abstract
The translocation of most eukaryotic secreted and integral membrane proteins occurs co-translationally at the endoplasmic reticulum (ER). These nascent polypeptides are recognized on the ribosome by the signal recognition particle (SRP), targeted to the ER, and translocated across or inserted into the membrane by the Sec61 translocation channel. Structural analysis of these co-translational processes has been challenging due to the size, complexity, and flexibility of the targeting and translocation machinery. Recent technological advances in cryo-electron microscopy (cryo-EM) have resulted in increasingly powerful tools to study large, heterogeneous, and low-abundance samples. These advances are being utilized to obtain near-atomic resolution reconstructions of functional translation, targeting, and translocation intermediates, paving the way to a mechanistic understanding of protein biogenesis.
Collapse
Affiliation(s)
- Rebecca M Voorhees
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Ramanujan S Hegde
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom.
| |
Collapse
|
129
|
Parlea LG, Sweeney BA, Hosseini-Asanjan M, Zirbel CL, Leontis NB. The RNA 3D Motif Atlas: Computational methods for extraction, organization and evaluation of RNA motifs. Methods 2016; 103:99-119. [PMID: 27125735 DOI: 10.1016/j.ymeth.2016.04.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 11/30/2022] Open
Abstract
RNA 3D motifs occupy places in structured RNA molecules that correspond to the hairpin, internal and multi-helix junction "loops" of their secondary structure representations. As many as 40% of the nucleotides of an RNA molecule can belong to these structural elements, which are distinct from the regular double helical regions formed by contiguous AU, GC, and GU Watson-Crick basepairs. With the large number of atomic- or near atomic-resolution 3D structures appearing in a steady stream in the PDB/NDB structure databases, the automated identification, extraction, comparison, clustering and visualization of these structural elements presents an opportunity to enhance RNA science. Three broad applications are: (1) identification of modular, autonomous structural units for RNA nanotechnology, nanobiology and synthetic biology applications; (2) bioinformatic analysis to improve RNA 3D structure prediction from sequence; and (3) creation of searchable databases for exploring the binding specificities, structural flexibility, and dynamics of these RNA elements. In this contribution, we review methods developed for computational extraction of hairpin and internal loop motifs from a non-redundant set of high-quality RNA 3D structures. We provide a statistical summary of the extracted hairpin and internal loop motifs in the most recent version of the RNA 3D Motif Atlas. We also explore the reliability and accuracy of the extraction process by examining its performance in clustering recurrent motifs from homologous ribosomal RNA (rRNA) structures. We conclude with a summary of remaining challenges, especially with regard to extraction of multi-helix junction motifs.
Collapse
Affiliation(s)
- Lorena G Parlea
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
| | - Blake A Sweeney
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
| | | | - Craig L Zirbel
- Department of Mathematics and Statistics, Bowling Green State University, Bowling Green, OH 43403, USA.
| | - Neocles B Leontis
- Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403, USA.
| |
Collapse
|
130
|
Liu Y, Deisenroth C, Zhang Y. RP-MDM2-p53 Pathway: Linking Ribosomal Biogenesis and Tumor Surveillance. Trends Cancer 2016; 2:191-204. [PMID: 28741571 DOI: 10.1016/j.trecan.2016.03.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/03/2016] [Accepted: 03/04/2016] [Indexed: 12/18/2022]
Abstract
Ribosomal biogenesis is tightly associated with cellular activities, such as growth, proliferation, and cell cycle progression. Perturbations in ribosomal biogenesis can initiate so-called nucleolar stress. The process through which ribosomal proteins (RPs) transduce nucleolar stress signals via MDM2 to p53 has been described as a crucial tumor-suppression mechanism. In this review we focus on recent progress pertaining to the function and mechanism of RPs in association with the MDM2-p53 tumor-suppression network, and the potential implications this surveillance network has for cancer development.
Collapse
Affiliation(s)
- Yong Liu
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Chad Deisenroth
- The Hamner Institutes for Health Sciences, Institute for Chemical Safety Sciences, 6 Davis Drive, PO Box 12137, Research Triangle Park, NC 27709, USA
| | - Yanping Zhang
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou, Jiangsu 221002, China.
| |
Collapse
|
131
|
Abstract
Mitochondrial ribosomes (mitoribosomes) perform protein synthesis inside mitochondria, the organelles responsible for energy conversion and adenosine triphosphate production in eukaryotic cells. Throughout evolution, mitoribosomes have become functionally specialized for synthesizing mitochondrial membrane proteins, and this has been accompanied by large changes to their structure and composition. We review recent high-resolution structural data that have provided unprecedented insight into the structure and function of mitoribosomes in mammals and fungi.
Collapse
Affiliation(s)
- Basil J Greber
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland; .,*Present address: California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720-3220
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland;
| |
Collapse
|
132
|
Singh H, Li M, Hall L, Chen S, Sukur S, Lu R, Caputo A, Meredith AL, Stefani E, Toro L. MaxiK channel interactome reveals its interaction with GABA transporter 3 and heat shock protein 60 in the mammalian brain. Neuroscience 2016; 317:76-107. [PMID: 26772433 PMCID: PMC4737998 DOI: 10.1016/j.neuroscience.2015.12.058] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/29/2015] [Accepted: 12/30/2015] [Indexed: 10/22/2022]
Abstract
Large conductance voltage and calcium-activated potassium (MaxiK) channels are activated by membrane depolarization and elevated cytosolic Ca(2+). In the brain, they localize to neurons and astrocytes, where they play roles such as resetting the membrane potential during an action potential, neurotransmitter release, and neurovascular coupling. MaxiK channels are known to associate with several modulatory proteins and accessory subunits, and each of these interactions can have distinct physiological consequences. To uncover new players in MaxiK channel brain physiology, we applied a directed proteomic approach and obtained MaxiK channel pore-forming α subunit brain interactome using specific antibodies. Controls included immunoprecipitations with rabbit immunoglobulin G (IgG) and with anti-MaxiK antibodies in wild type and MaxiK channel knockout mice (Kcnma1(-/-)), respectively. We have found known and unreported interactive partners that localize to the plasma membrane, extracellular space, cytosol and intracellular organelles including mitochondria, nucleus, endoplasmic reticulum and Golgi apparatus. Localization of MaxiK channel to mitochondria was further confirmed using purified brain mitochondria colabeled with MitoTracker. Independent proof of MaxiK channel interaction with previously unidentified partners is given for GABA transporter 3 (GAT3) and heat shock protein 60 (HSP60). In human embryonic kidney 293 cells containing SV40 T-antigen (HEK293T) cells, both GAT3 and HSP60 coimmunoprecipitated and colocalized with MaxiK channel; colabeling was observed mainly at the cell periphery with GAT3 and intracellularly with HSP60 with protein proximity indices of ∼ 0.6 and ∼ 0.4, respectively. In rat primary hippocampal neurons, colocalization index was identical for GAT3 (∼ 0.6) and slightly higher for HSP60 (∼ 0.5) association with MaxiK channel. The results of this study provide a complete interactome of MaxiK channel the mouse brain, further establish the localization of MaxiK channel in the mouse brain mitochondria and demonstrate the interaction of MaxiK channel with GAT3 and HSP60 in neurons. The interaction of MaxiK channel with GAT3 opens the possibility of a role of MaxiK channel in GABA homeostasis and signaling.
Collapse
Affiliation(s)
- H Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA; Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - M Li
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - L Hall
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - S Chen
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - S Sukur
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
| | - R Lu
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - A Caputo
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| | - A L Meredith
- Department of Physiology, University of Maryland, Baltimore, MD 21201, USA.
| | - E Stefani
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA; Department of Physiology, University of California, Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA.
| | - L Toro
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA; Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA; Cardiovascular Research Laboratory, University of California, Los Angeles, CA 90095, USA.
| |
Collapse
|
133
|
Schmidt C, Becker T, Heuer A, Braunger K, Shanmuganathan V, Pech M, Berninghausen O, Wilson DN, Beckmann R. Structure of the hypusinylated eukaryotic translation factor eIF-5A bound to the ribosome. Nucleic Acids Res 2016; 44:1944-51. [PMID: 26715760 PMCID: PMC4770232 DOI: 10.1093/nar/gkv1517] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 12/31/2022] Open
Abstract
During protein synthesis, ribosomes become stalled on polyproline-containing sequences, unless they are rescued in archaea and eukaryotes by the initiation factor 5A (a/eIF-5A) and in bacteria by the homologous protein EF-P. While a structure of EF-P bound to the 70S ribosome exists, structural insight into eIF-5A on the 80S ribosome has been lacking. Here we present a cryo-electron microscopy reconstruction of eIF-5A bound to the yeast 80S ribosome at 3.9 Å resolution. The structure reveals that the unique and functionally essential post-translational hypusine modification reaches toward the peptidyltransferase center of the ribosome, where the hypusine moiety contacts A76 of the CCA-end of the P-site tRNA. These findings would support a model whereby eIF-5A stimulates peptide bond formation on polyproline-stalled ribosomes by stabilizing and orienting the CCA-end of the P-tRNA, rather than by directly contributing to the catalysis.
Collapse
Affiliation(s)
- Christian Schmidt
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Thomas Becker
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - André Heuer
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Katharina Braunger
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Vivekanandan Shanmuganathan
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Markus Pech
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Otto Berninghausen
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Daniel N Wilson
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Roland Beckmann
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| |
Collapse
|
134
|
Shen CL, Liu CD, You RI, Ching YH, Liang J, Ke L, Chen YL, Chen HC, Hsu HJ, Liou JW, Kieff E, Peng CW. Ribosome Protein L4 is essential for Epstein-Barr Virus Nuclear Antigen 1 function. Proc Natl Acad Sci U S A 2016; 113:2229-34. [PMID: 26858444 PMCID: PMC4776490 DOI: 10.1073/pnas.1525444113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Epstein-Barr Virus (EBV) Nuclear Antigen 1 (EBNA1)-mediated origin of plasmid replication (oriP) DNA episome maintenance is essential for EBV-mediated tumorigenesis. We have now found that EBNA1 binds to Ribosome Protein L4 (RPL4). RPL4 shRNA knockdown decreased EBNA1 activation of an oriP luciferase reporter, EBNA1 DNA binding in lymphoblastoid cell lines, and EBV genome number per lymphoblastoid cell line. EBV infection increased RPL4 expression and redistributed RPL4 to cell nuclei. RPL4 and Nucleolin (NCL) were a scaffold for an EBNA1-induced oriP complex. The RPL4 N terminus cooperated with NCL-K429 to support EBNA1 and oriP-mediated episome binding and maintenance, whereas the NCL C-terminal K380 and K393 induced oriP DNA H3K4me2 modification and promoted EBNA1 activation of oriP-dependent transcription. These observations provide new insights into the mechanisms by which EBV uses NCL and RPL4 to establish persistent B-lymphoblastoid cell infection.
Collapse
Affiliation(s)
- Chih-Lung Shen
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan
| | - Cheng-Der Liu
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan
| | - Ren-In You
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Yung-Hao Ching
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Jun Liang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115
| | - Liangru Ke
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115
| | - Ya-Lin Chen
- Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Hong-Chi Chen
- Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Hao-Jen Hsu
- Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Je-Wen Liou
- Institute of Biochemical Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan
| | - Elliott Kieff
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115;
| | - Chih-Wen Peng
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan; Department of Life Sciences, Tzu Chi University, Sec. 3, Hualien 97004, Taiwan;
| |
Collapse
|
135
|
Ma C, Yan K, Tan D, Li N, Zhang Y, Yuan Y, Li Z, Dong MQ, Lei J, Gao N. Structural dynamics of the yeast Shwachman-Diamond syndrome protein (Sdo1) on the ribosome and its implication in the 60S subunit maturation. Protein Cell 2016; 7:187-200. [PMID: 26850260 PMCID: PMC4791427 DOI: 10.1007/s13238-015-0242-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 12/14/2015] [Indexed: 12/16/2022] Open
Abstract
The human Shwachman-Diamond syndrome (SDS) is an autosomal recessive disease caused by mutations in a highly conserved ribosome assembly factor SBDS. The functional role of SBDS is to cooperate with another assembly factor, elongation factor 1-like (Efl1), to promote the release of eukaryotic initiation factor 6 (eIF6) from the late-stage cytoplasmic 60S precursors. In the present work, we characterized, both biochemically and structurally, the interaction between the 60S subunit and SBDS protein (Sdo1p) from yeast. Our data show that Sdo1p interacts tightly with the mature 60S subunit in vitro through its domain I and II, and is capable of bridging two 60S subunits to form a stable 2:2 dimer. Structural analysis indicates that Sdo1p bind to the ribosomal P-site, in the proximity of uL16 and uL5, and with direct contact to H69 and H38. The dynamic nature of Sdo1p on the 60S subunit, together with its strategic binding position, suggests a surveillance role of Sdo1p in monitoring the conformational maturation of the ribosomal P-site. Altogether, our data support a conformational signal-relay cascade during late-stage 60S maturation, involving uL16, Sdo1p, and Efl1p, which interrogates the functional P-site to control the departure of the anti-association factor eIF6.
Collapse
Affiliation(s)
- Chengying Ma
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Kaige Yan
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Dan Tan
- National Institute of Biological Sciences, Beijing, 102206, China.,Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Ningning Li
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yixiao Zhang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yi Yuan
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhifei Li
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, 102206, China.,Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Jianlin Lei
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ning Gao
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| |
Collapse
|
136
|
Over-expressed RPL34 promotes malignant proliferation of non-small cell lung cancer cells. Gene 2016; 576:421-8. [DOI: 10.1016/j.gene.2015.10.053] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 10/21/2015] [Indexed: 01/18/2023]
|
137
|
Chakraborty B, Bhakta S, Sengupta J. Disassembly of yeast 80S ribosomes into subunits is a concerted action of ribosome-assisted folding of denatured protein. Biochem Biophys Res Commun 2016; 469:923-9. [DOI: 10.1016/j.bbrc.2015.12.107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 12/22/2015] [Indexed: 11/27/2022]
|
138
|
Greber BJ, Gerhardy S, Leitner A, Leibundgut M, Salem M, Boehringer D, Leulliot N, Aebersold R, Panse VG, Ban N. Insertion of the Biogenesis Factor Rei1 Probes the Ribosomal Tunnel during 60S Maturation. Cell 2015; 164:91-102. [PMID: 26709046 DOI: 10.1016/j.cell.2015.11.027] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 10/08/2015] [Accepted: 11/05/2015] [Indexed: 10/22/2022]
Abstract
Eukaryotic ribosome biogenesis depends on several hundred assembly factors to produce functional 40S and 60S ribosomal subunits. The final phase of 60S subunit biogenesis is cytoplasmic maturation, which includes the proofreading of functional centers of the 60S subunit and the release of several ribosome biogenesis factors. We report the cryo-electron microscopy (cryo-EM) structure of the yeast 60S subunit in complex with the biogenesis factors Rei1, Arx1, and Alb1 at 3.4 Å resolution. In addition to the network of interactions formed by Alb1, the structure reveals a mechanism for ensuring the integrity of the ribosomal polypeptide exit tunnel. Arx1 probes the entire set of inner-ring proteins surrounding the tunnel exit, and the C terminus of Rei1 is deeply inserted into the ribosomal tunnel, where it forms specific contacts along almost its entire length. We provide genetic and biochemical evidence that failure to insert the C terminus of Rei1 precludes subsequent steps of 60S maturation.
Collapse
Affiliation(s)
- Basil Johannes Greber
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Stefan Gerhardy
- Institute of Biochemistry, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Alexander Leitner
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Marc Leibundgut
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Michèle Salem
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Daniel Boehringer
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Nicolas Leulliot
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Ruedi Aebersold
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland; Faculty of Science, University of Zurich, CH-8057 Zurich, Switzerland
| | - Vikram Govind Panse
- Institute of Biochemistry, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Nenad Ban
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.
| |
Collapse
|
139
|
Ohmayer U, Gil-Hernández Á, Sauert M, Martín-Marcos P, Tamame M, Tschochner H, Griesenbeck J, Milkereit P. Studies on the Coordination of Ribosomal Protein Assembly Events Involved in Processing and Stabilization of Yeast Early Large Ribosomal Subunit Precursors. PLoS One 2015; 10:e0143768. [PMID: 26642313 PMCID: PMC4671574 DOI: 10.1371/journal.pone.0143768] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/09/2015] [Indexed: 12/11/2022] Open
Abstract
Cellular production of ribosomes involves the formation of highly defined interactions between ribosomal proteins (r-proteins) and ribosomal RNAs (rRNAs). Moreover in eukaryotic cells, efficient ribosome maturation requires the transient association of a large number of ribosome biogenesis factors (RBFs) with newly forming ribosomal subunits. Here, we investigated how r-protein assembly events in the large ribosomal subunit (LSU) rRNA domain II are coordinated with each other and with the association of RBFs in early LSU precursors of the yeast Saccharomyces cerevisiae. Specific effects on the pre-ribosomal association of RBFs could be observed in yeast mutants blocked in LSU rRNA domain II assembly. Moreover, formation of a cluster of r-proteins was identified as a downstream event in LSU rRNA domain II assembly. We analyzed in more detail the functional relevance of eukaryote specific bridges established by this r-protein cluster between LSU rRNA domain II and VI and discuss how they can support the stabilization and efficient processing of yeast early LSU precursor RNAs.
Collapse
Affiliation(s)
- Uli Ohmayer
- Lehrstuhl für Biochemie III, Universität Regensburg, Regensburg, Germany
| | - Álvaro Gil-Hernández
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Salamanca, Spain
| | - Martina Sauert
- Lehrstuhl für Biochemie III, Universität Regensburg, Regensburg, Germany
| | - Pilar Martín-Marcos
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Salamanca, Spain
| | - Mercedes Tamame
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Salamanca, Spain
- * E-mail: (MT); (HT); (JG); (PM)
| | - Herbert Tschochner
- Lehrstuhl für Biochemie III, Universität Regensburg, Regensburg, Germany
- * E-mail: (MT); (HT); (JG); (PM)
| | - Joachim Griesenbeck
- Lehrstuhl für Biochemie III, Universität Regensburg, Regensburg, Germany
- * E-mail: (MT); (HT); (JG); (PM)
| | - Philipp Milkereit
- Lehrstuhl für Biochemie III, Universität Regensburg, Regensburg, Germany
- * E-mail: (MT); (HT); (JG); (PM)
| |
Collapse
|
140
|
Garcia-Esparcia P, Hernández-Ortega K, Koneti A, Gil L, Delgado-Morales R, Castaño E, Carmona M, Ferrer I. Altered machinery of protein synthesis is region- and stage-dependent and is associated with α-synuclein oligomers in Parkinson's disease. Acta Neuropathol Commun 2015; 3:76. [PMID: 26621506 PMCID: PMC4666041 DOI: 10.1186/s40478-015-0257-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 11/14/2015] [Indexed: 01/17/2023] Open
Abstract
INTRODUCTION Parkinson's disease (PD) is characterized by the accumulation of abnormal α-synuclein in selected regions of the brain following a gradient of severity with disease progression. Whether this is accompanied by globally altered protein synthesis is poorly documented. The present study was carried out in PD stages 1-6 of Braak and middle-aged (MA) individuals without alterations in brain in the substantia nigra, frontal cortex area 8, angular gyrus, precuneus and putamen. RESULTS Reduced mRNA expression of nucleolar proteins nucleolin (NCL), nucleophosmin (NPM1), nucleoplasmin 3 (NPM3) and upstream binding transcription factor (UBF), decreased NPM1 but not NPM3 nucleolar protein immunostaining in remaining neurons; diminished 18S rRNA, 28S rRNA; reduced expression of several mRNAs encoding ribosomal protein (RP) subunits; and altered protein levels of initiation factor eIF3 and elongation factor eEF2 of protein synthesis was found in the substantia nigra in PD along with disease progression. Although many of these changes can be related to neuron loss in the substantia nigra, selective alteration of certain factors indicates variable degree of vulnerability of mRNAs, rRNAs and proteins in degenerating sustantia nigra. NPM1 mRNA and 18S rRNA was increased in the frontal cortex area 8 at stage 5-6; modifications were less marked and region-dependent in the angular gyrus and precuneus. Several RPs were abnormally regulated in the frontal cortex area 8 and precuneus, but only one RP in the angular gyrus, in PD. Altered levels of eIF3 and eIF1, and decrease eEF1A and eEF2 protein levels were observed in the frontal cortex in PD. No modifications were found in the putamen at any time of the study except transient modifications in 28S rRNA and only one RP mRNA at stages 5-6. These observations further indicate marked region-dependent and stage-dependent alterations in the cerebral cortex in PD. Altered solubility and α-synuclein oligomer formation, assessed in total homogenate fractions blotted with anti-α-synuclein oligomer-specific antibody, was demonstrated in the substantia nigra and frontal cortex, but not in the putamen, in PD. Dramatic increase in α-synuclein oligomers was also seen in fluorescent-activated cell sorter (FACS)-isolated nuclei in the frontal cortex in PD. CONCLUSIONS Altered machinery of protein synthesis is altered in the substantia nigra and cerebral cortex in PD being the frontal cortex area 8 more affected than the angular gyrus and precuneus; in contrast, pathways of protein synthesis are apparently preserved in the putamen. This is associated with the presence of α-synuclein oligomeric species in total homogenates; substantia nigra and frontal cortex are enriched, albeit with different band patterns, in α-synuclein oligomeric species, whereas α-synuclein oligomers are not detected in the putamen.
Collapse
Affiliation(s)
- Paula Garcia-Esparcia
- Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - Karina Hernández-Ortega
- Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - Anusha Koneti
- Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - Laura Gil
- Department of Genetics, Medical School, Alfonso X el Sabio University, Villanueva de la Cañada, Madrid, Spain
| | - Raul Delgado-Morales
- Cancer Epigenetics and Biology Program, IDIBELL, Hospitalet de Llobregat, Barcelona, Spain
| | - Ester Castaño
- Biology-Bellvitge Unit, Scientific and Technological Centers-University of Barcelona (CCiTUB), Hospitalet de Llobregat, Barcelona, Spain
| | - Margarita Carmona
- Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - Isidre Ferrer
- Institute of Neuropathology, Bellvitge University Hospital, University of Barcelona, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat; Biomedical Research Center of Neurodegenerative Diseases (CIBERNED), Barcelona, Spain.
- Institute of Neuropathology, Service of Pathologic Anatomy, Bellvitge University Hospital, carrer Feixa Llarga s/n, 08907, Hospitalet de Llobregat, Spain.
| |
Collapse
|
141
|
Gallo S, Manfrini N. Working hard at the nexus between cell signaling and the ribosomal machinery: An insight into the roles of RACK1 in translational regulation. ACTA ACUST UNITED AC 2015; 3:e1120382. [PMID: 26824030 DOI: 10.1080/21690731.2015.1120382] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 10/19/2015] [Accepted: 11/09/2015] [Indexed: 02/08/2023]
Abstract
RACK1 is a ribosome-associated protein which functions as a receptor for activated PKCs. It also acts as a scaffold for many other proteins involved in diverse signaling pathways, e.g. Src, JNK, PDE4D and FAK signaling. With such a broad interactome, RACK1 has been suggested to function as a linker between cell signaling and the translation machinery. Accordingly, RACK1 modulates translation at different levels in several model organisms. For instance, it regulates ribosome stalling and mRNA quality control in yeasts and promotes translation efficiency downstream of specific cellular stimuli in mammals. However, the molecular mechanism by which RACK1 exerts these roles is widely uncharacterized. Moreover, the full list of ribosome-recruited RACK1 interactors still needs characterization. Here we discuss in vivo and in vitro findings to better delineate the roles of RACK1 in regulating ribosome function and translation.
Collapse
Affiliation(s)
- Simone Gallo
- Molecular Histology and Cell Growth Unit; National Institute of Molecular Genetics - INGM "Romeo and Enrica Invernizzi" ; Milan, Italy
| | - Nicola Manfrini
- Molecular Histology and Cell Growth Unit; National Institute of Molecular Genetics - INGM "Romeo and Enrica Invernizzi" ; Milan, Italy
| |
Collapse
|
142
|
Weis F, Giudice E, Churcher M, Jin L, Hilcenko C, Wong CC, Traynor D, Kay RR, Warren AJ. Mechanism of eIF6 release from the nascent 60S ribosomal subunit. Nat Struct Mol Biol 2015; 22:914-9. [PMID: 26479198 PMCID: PMC4871238 DOI: 10.1038/nsmb.3112] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/17/2015] [Indexed: 12/20/2022]
Abstract
SBDS protein (deficient in the inherited leukemia-predisposition disorder Shwachman-Diamond syndrome) and the GTPase EFL1 (an EF-G homolog) activate nascent 60S ribosomal subunits for translation by catalyzing eviction of the antiassociation factor eIF6 from nascent 60S ribosomal subunits. However, the mechanism is completely unknown. Here, we present cryo-EM structures of human SBDS and SBDS-EFL1 bound to Dictyostelium discoideum 60S ribosomal subunits with and without endogenous eIF6. SBDS assesses the integrity of the peptidyl (P) site, bridging uL16 (mutated in T-cell acute lymphoblastic leukemia) with uL11 at the P-stalk base and the sarcin-ricin loop. Upon EFL1 binding, SBDS is repositioned around helix 69, thus facilitating a conformational switch in EFL1 that displaces eIF6 by competing for an overlapping binding site on the 60S ribosomal subunit. Our data reveal the conserved mechanism of eIF6 release, which is corrupted in both inherited and sporadic leukemias.
Collapse
Affiliation(s)
- Félix Weis
- Cambridge Institute for Medical Research, Cambridge, UK
- Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Emmanuel Giudice
- Université de Rennes 1, Centre Nationale de la Recherche Scientifique, Unité Mixte de Recherche 6290, Institut de Génétique et Développement de Rennes, Rennes, France
| | - Mark Churcher
- Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Li Jin
- Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Christine Hilcenko
- Cambridge Institute for Medical Research, Cambridge, UK
- Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Chi C Wong
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Cambridge, UK
| | - David Traynor
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Robert R Kay
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Alan J Warren
- Cambridge Institute for Medical Research, Cambridge, UK
- Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| |
Collapse
|
143
|
Homology Modeling Procedures for Cytoskeletal Proteins of Tetrahymena and Other Ciliated Protists. Methods Mol Biol 2015; 1365:415-27. [PMID: 26498800 DOI: 10.1007/978-1-4939-3124-8_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
In recent years there has been an explosive increase in the number of annotated protein sequences available through genome sequencing, as well as an accumulation of published protein structural data based on crystallographic and NMR methods. When taken together with the development of computational methods for the prediction of protein structural and functional properties through homology modeling, an opportunity exists for prediction of properties of cytoskeletal proteins in a suitable model organism, such as Tetrahymena thermophila and its ciliated protist relatives. In particular, the recently sequenced genome of T. thermophila, long a model for cytoskeletal studies, provides a good starting point for undertaking such homology modeling studies. Homology modeling can produce functional predictions, for example regarding potential molecular interactions, that are of great interest to the drug industry and Tetrahymena is an attractive model system in which to follow up computational predictions with experimental analyses. We provide here procedures that can be followed to gain entry into this promising avenue of analysis.
Collapse
|
144
|
Parker MS, Sallee FR, Park EA, Parker SL. Homoiterons and expansion in ribosomal RNAs. FEBS Open Bio 2015; 5:864-76. [PMID: 26636029 PMCID: PMC4637361 DOI: 10.1016/j.fob.2015.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/30/2015] [Accepted: 10/14/2015] [Indexed: 11/27/2022] Open
Abstract
Homoiterons like GGGGGGG stabilize ribosomal RNAs of thermophile prokaryotes. In eukaryotes, homoiterons are much more abundant in RNA of the larger subunit (LSU). The LSU repeats increase with phylogenetic rank to 28% entire RNA sequence in hominids. In mammal LSU RNAs, these repeats constitute 45% of the massive expansion segments. These repeats may help in anchoring of ribosomes and export of secretory proteins.
Ribosomal RNAs in both prokaryotes and eukaryotes feature numerous repeats of three or more nucleotides with the same nucleobase (homoiterons). In prokaryotes these repeats are much more frequent in thermophile compared to mesophile or psychrophile species, and have similar frequency in both large RNAs. These features point to use of prokaryotic homoiterons in stabilization of both ribosomal subunits. The two large RNAs of eukaryotic cytoplasmic ribosomes have expanded to a different degree across the evolutionary ladder. The big RNA of the larger subunit (60S LSU) evolved expansion segments of up to 2400 nucleotides, and the smaller subunit (40S SSU) RNA acquired expansion segments of not more than 700 nucleotides. In the examined eukaryotes abundance of rRNA homoiterons generally follows size and nucleotide bias of the expansion segments, and increases with GC content and especially with phylogenetic rank. Both the nucleotide bias and frequency of homoiterons are much larger in metazoan and angiosperm LSU compared to the respective SSU RNAs. This is especially pronounced in the tetrapod vertebrates and seems to culminate in the hominid mammals. The stability of secondary structure in polyribonucleotides would significantly connect to GC content, and should also relate to G and C homoiteron content. RNA modeling points to considerable presence of homoiteron-rich double-stranded segments especially in vertebrate LSU RNAs, and homoiterons with four or more nucleotides in the vertebrate and angiosperm LSU RNAs are largely confined to the expansion segments. These features could mainly relate to protein export function and attachment of LSU to endoplasmic reticulum and other subcellular networks.
Collapse
Key Words
- ES, an expansion segment
- LSU, large cytoplasmic ribosome subunit (50S in prokaryotes and archaea, 60S in eukaryotes)
- PCN, homoionic motifs with ⩾3% and ⩾50% ionic residues, found especially in Polynucleotide-binding proteins, Carrier proteins and Nuclear localization signals
- RNA expansion segment
- RNA nucleotide bias
- RNA nucleotide repeat
- SSU, small cytoplasmic ribosome subunit (30S in prokaryotes and archaea, 40S in eukaryotes)
- XN or NX, [X = a number] a nucleotide unit with same nucleobases (homoiteron), such as 4U or U4 for UUUU
- aa, amino acid residues
- mRNP, messenger ribonucleoprotein
- ncRNA, non-coding RNA
- nt, nucleotides
- u, nucleotide unit
Collapse
Affiliation(s)
- Michael S Parker
- Department of Microbiology and Molecular Cell Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Floyd R Sallee
- Department of Psychiatry, University of Cincinnati School of Medicine, Cincinnati, OH 45276, USA
| | - Edwards A Park
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Steven L Parker
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| |
Collapse
|
145
|
Pillet B, García-Gómez JJ, Pausch P, Falquet L, Bange G, de la Cruz J, Kressler D. The Dedicated Chaperone Acl4 Escorts Ribosomal Protein Rpl4 to Its Nuclear Pre-60S Assembly Site. PLoS Genet 2015; 11:e1005565. [PMID: 26447800 PMCID: PMC4598080 DOI: 10.1371/journal.pgen.1005565] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/11/2015] [Indexed: 11/19/2022] Open
Abstract
Ribosomes are the highly complex macromolecular assemblies dedicated to the synthesis of all cellular proteins from mRNA templates. The main principles underlying the making of ribosomes are conserved across eukaryotic organisms and this process has been studied in most detail in the yeast Saccharomyces cerevisiae. Yeast ribosomes are composed of four ribosomal RNAs (rRNAs) and 79 ribosomal proteins (r-proteins). Most r-proteins need to be transported from the cytoplasm to the nucleus where they get incorporated into the evolving pre-ribosomal particles. Due to the high abundance and difficult physicochemical properties of r-proteins, their correct folding and fail-safe targeting to the assembly site depends largely on general, as well as highly specialized, chaperone and transport systems. Many r-proteins contain universally conserved or eukaryote-specific internal loops and/or terminal extensions, which were shown to mediate their nuclear targeting and association with dedicated chaperones in a growing number of cases. The 60S r-protein Rpl4 is particularly interesting since it harbours a conserved long internal loop and a prominent C-terminal eukaryote-specific extension. Here we show that both the long internal loop and the C-terminal eukaryote-specific extension are strictly required for the functionality of Rpl4. While Rpl4 contains at least five distinct nuclear localization signals (NLS), the C-terminal part of the long internal loop associates with a specific binding partner, termed Acl4. Absence of Acl4 confers a severe slow-growth phenotype and a deficiency in the production of 60S subunits. Genetic and biochemical evidence indicates that Acl4 can be considered as a dedicated chaperone of Rpl4. Notably, Acl4 localizes to both the cytoplasm and nucleus and it has the capacity to capture nascent Rpl4 in a co-translational manner. Taken together, our findings indicate that the dedicated chaperone Acl4 accompanies Rpl4 from the cytoplasm to its pre-60S assembly site in the nucleus.
Collapse
Affiliation(s)
- Benjamin Pillet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Juan J. García-Gómez
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Patrick Pausch
- LOEWE Center for Synthetic Microbiology and Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Laurent Falquet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
- Swiss Institute of Bioinformatics, University of Fribourg, Fribourg, Switzerland
| | - Gert Bange
- LOEWE Center for Synthetic Microbiology and Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail:
| |
Collapse
|
146
|
Li X, Sun Q, Jiang C, Yang K, Hung LW, Zhang J, Sacchettini JC. Structure of Ribosomal Silencing Factor Bound to Mycobacterium tuberculosis Ribosome. Structure 2015; 23:1858-1865. [PMID: 26299947 PMCID: PMC4718548 DOI: 10.1016/j.str.2015.07.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 07/09/2015] [Accepted: 07/10/2015] [Indexed: 01/07/2023]
Abstract
The ribosomal silencing factor RsfS slows cell growth by inhibiting protein synthesis during periods of diminished nutrient availability. The crystal structure of Mycobacterium tuberculosis (Mtb) RsfS, together with the cryo-electron microscopy (EM) structure of the large subunit 50S of Mtb ribosome, reveals how inhibition of protein synthesis by RsfS occurs. RsfS binds to the 50S at L14, which, when occupied, blocks the association of the small subunit 30S. Although Mtb RsfS is a dimer in solution, only a single subunit binds to 50S. The overlap between the dimer interface and the L14 binding interface confirms that the RsfS dimer must first dissociate to a monomer in order to bind to L14. RsfS interacts primarily through electrostatic and hydrogen bonding to L14. The EM structure shows extended rRNA density that it is not found in the Escherichia coli ribosome, the most striking of these being the extended RNA helix of H54a.
Collapse
Affiliation(s)
- Xiaojun Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Qingan Sun
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Cai Jiang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Kailu Yang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Li-Wei Hung
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA
| | - Junjie Zhang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA,Correspondence: (J.C.S.), (J.Z.)
| | - James C. Sacchettini
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA,Correspondence: (J.C.S.), (J.Z.)
| |
Collapse
|
147
|
Doris SM, Smith DR, Beamesderfer JN, Raphael BJ, Nathanson JA, Gerbi SA. Universal and domain-specific sequences in 23S-28S ribosomal RNA identified by computational phylogenetics. RNA (NEW YORK, N.Y.) 2015; 21:1719-1730. [PMID: 26283689 PMCID: PMC4574749 DOI: 10.1261/rna.051144.115] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 07/07/2015] [Indexed: 06/01/2023]
Abstract
Comparative analysis of ribosomal RNA (rRNA) sequences has elucidated phylogenetic relationships. However, this powerful approach has not been fully exploited to address ribosome function. Here we identify stretches of evolutionarily conserved sequences, which correspond with regions of high functional importance. For this, we developed a structurally aligned database, FLORA (full-length organismal rRNA alignment) to identify highly conserved nucleotide elements (CNEs) in 23S-28S rRNA from each phylogenetic domain (Eukarya, Bacteria, and Archaea). Universal CNEs (uCNEs) are conserved in sequence and structural position in all three domains. Those in regions known to be essential for translation validate our approach. Importantly, some uCNEs reside in areas of unknown function, thus identifying novel sequences of likely great importance. In contrast to uCNEs, domain-specific CNEs (dsCNEs) are conserved in just one phylogenetic domain. This is the first report of conserved sequence elements in rRNA that are domain-specific; they are largely a eukaryotic phenomenon. The locations of the eukaryotic dsCNEs within the structure of the ribosome suggest they may function in nascent polypeptide transit through the ribosome tunnel and in tRNA exit from the ribosome. Our findings provide insights and a resource for ribosome function studies.
Collapse
Affiliation(s)
- Stephen M Doris
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Providence, Rhode Island 02912, USA
| | - Deborah R Smith
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Providence, Rhode Island 02912, USA
| | - Julia N Beamesderfer
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Providence, Rhode Island 02912, USA
| | - Benjamin J Raphael
- Department of Computer Science and Center for Computational Molecular Biology, Brown University Division of Biology and Medicine, Providence, Rhode Island 02912, USA
| | - Judith A Nathanson
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Providence, Rhode Island 02912, USA
| | - Susan A Gerbi
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Providence, Rhode Island 02912, USA
| |
Collapse
|
148
|
Baloglu MC, Ulu F, Altunoglu YC, Pekol S, Alagoz G, Ese O. Identification, molecular characterization and expression analysis ofRPL24genes in three Cucurbitaceae family members: cucumber, melon and watermelon. BIOTECHNOL BIOTEC EQ 2015. [DOI: 10.1080/13102818.2015.1079144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
|
149
|
Nogales E, Scheres SHW. Cryo-EM: A Unique Tool for the Visualization of Macromolecular Complexity. Mol Cell 2015; 58:677-89. [PMID: 26000851 DOI: 10.1016/j.molcel.2015.02.019] [Citation(s) in RCA: 235] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
3D cryo-electron microscopy (cryo-EM) is an expanding structural biology technique that has recently undergone a quantum leap progression in its achievable resolution and its applicability to the study of challenging biological systems. Because crystallization is not required, only small amounts of sample are needed, and because images can be classified in a computer, the technique has the potential to deal with compositional and conformational mixtures. Therefore, cryo-EM can be used to investigate complete and fully functional macromolecular complexes in different functional states, providing a richness of biological insight. In this review, we underlie some of the principles behind the cryo-EM methodology of single particle analysis and discuss some recent results of its application to challenging systems of paramount biological importance. We place special emphasis on new methodological developments that are leading to an explosion of new studies, many of which are reaching resolutions that could only be dreamed of just a couple of years ago.
Collapse
Affiliation(s)
- Eva Nogales
- Molecular and Cell Biology Department, UC Berkeley, Berkeley, CA 94720-3220, USA; Howard Hughes Medical Institute, UC Berkeley, Berkeley, CA 94720-3220, USA; Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Sjors H W Scheres
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| |
Collapse
|
150
|
Abstract
A veritable explosion of primary research papers within the past 10 years focuses on nucleolar and ribosomal stress, and for good reason: with ribosome biosynthesis consuming ~80% of a cell’s energy, nearly all metabolic and signaling pathways lead ultimately to or from the nucleolus. We begin by describing p53 activation upon nucleolar stress resulting in cell cycle arrest or apoptosis. The significance of this mechanism cannot be understated, as oncologists are now inducing nucleolar stress strategically in cancer cells as a potential anti-cancer therapy. We also summarize the human ribosomopathies, syndromes in which ribosome biogenesis or function are impaired leading to birth defects or bone narrow failures; the perplexing problem in the ribosomopathies is why only certain cells are affected despite the fact that the causative mutation is systemic. We then describe p53-independent nucleolar stress, first in yeast which lacks p53, and then in other model metazoans that lack MDM2, the critical E3 ubiquitin ligase that normally inactivates p53. Do these presumably ancient p53-independent nucleolar stress pathways remain latent in human cells? If they still exist, can we use them to target >50% of known human cancers that lack functional p53?
Collapse
Affiliation(s)
- Allison James
- a Department of Biological Sciences; Louisiana State University; Baton Rouge, LA USA
| | | | | | | | | |
Collapse
|