1
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Amin A, Wu R, Khan MA, Cheung MH, Liang Y, Liu C, Zhu G, Yu ZL, Liang C. An essential Noc3p dimerization cycle mediates ORC double-hexamer formation in replication licensing. Life Sci Alliance 2023; 6:e202201594. [PMID: 36599624 PMCID: PMC9813392 DOI: 10.26508/lsa.202201594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 12/17/2022] [Accepted: 12/19/2022] [Indexed: 01/05/2023] Open
Abstract
Replication licensing, a prerequisite of DNA replication, helps to ensure once-per-cell-cycle genome duplication. Some DNA replication-initiation proteins are sequentially loaded onto replication origins to form pre-replicative complexes (pre-RCs). ORC and Noc3p bind replication origins throughout the cell cycle, providing a platform for pre-RC assembly. We previously reported that cell cycle-dependent ORC dimerization is essential for the chromatin loading of the symmetric MCM double-hexamers. Here, we used Saccharomyces cerevisiae separation-of-function NOC3 mutants to confirm the separable roles of Noc3p in DNA replication and ribosome biogenesis. We also show that an essential and cell cycle-dependent Noc3p dimerization cycle regulates the ORC dimerization cycle. Noc3p dimerizes at the M-to-G1 transition and de-dimerizes in S-phase. The Noc3p dimerization cycle coupled with the ORC dimerization cycle enables replication licensing, protects nascent sister replication origins after replication initiation, and prevents re-replication. This study has revealed a new mechanism of replication licensing and elucidated the molecular mechanism of Noc3p as a mediator of ORC dimerization in pre-RC formation.
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Affiliation(s)
- Aftab Amin
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Rentian Wu
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Muhammad Ajmal Khan
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Man Hei Cheung
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yanting Liang
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Changdong Liu
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Guang Zhu
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Zhi-Ling Yu
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Chun Liang
- Division of Life Science, Center for Cancer Research, and State Key Lab of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
- EnKang Pharmaceuticals (Guangzhou), Ltd., Guangzhou, China
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2
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Lin S, Rajan S, Lemberg S, Altawil M, Anderson K, Bryant R, Cappeta S, Chin B, Hamdan I, Hamer A, Hyzny R, Karp A, Lee D, Lim A, Nayak M, Palaniappan V, Park S, Satishkumar S, Seth A, Sri Dasari U, Toppari E, Vyas A, Walker J, Weston E, Zafar A, Zielke C, Mahabeleshwar GH, Tartakoff AM. Production of nascent ribosome precursors within the nucleolar microenvironment of Saccharomyces cerevisiae. Genetics 2022; 221:iyac070. [PMID: 35657327 PMCID: PMC9252279 DOI: 10.1093/genetics/iyac070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
35S rRNA transcripts include a 5'-external transcribed spacer followed by rRNAs of the small and large ribosomal subunits. Their processing yields massive precursors that include dozens of assembly factor proteins. In Saccharomyces cerevisiae, nucleolar assembly factors form 2 coaxial layers/volumes around ribosomal DNA. Most of these factors are cyclically recruited from a latent state to an operative state, and are extensively conserved. The layers match, at least approximately, known subcompartments found in higher eukaryotic cells. ∼80% of assembly factors are essential. The number of copies of these assembly factors is comparable to the number of nascent transcripts. Moreover, they exhibit "isoelectric balance," with RNA-binding candidate "nucleator" assembly factors being notably basic. The physical properties of pre-small subunit and pre-large subunit assembly factors are similar, as are their 19 motif signatures detected by hierarchical clustering, unlike motif signatures of the 5'-external transcribed spacer rRNP. Additionally, many assembly factors lack shared motifs. Taken together with the progression of rRNP composition during subunit maturation, and the realization that the ribosomal DNA cable is initially bathed in a subunit-nonspecific assembly factor reservoir/microenvironment, we propose a "3-step subdomain assembly model": Step (1): predominantly basic assembly factors sequentially nucleate sites along nascent rRNA; Step (2): the resulting rRNPs recruit numerous less basic assembly factors along with notably basic ribosomal proteins; Step (3): rRNPs in nearby subdomains consolidate. Cleavages of rRNA then promote release of rRNPs to the nucleoplasm, likely facilitated by the persistence of assembly factors that were already associated with nucleolar precursors.
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Affiliation(s)
- Samantha Lin
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Suchita Rajan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sofia Lemberg
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark Altawil
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Katherine Anderson
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ruth Bryant
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sebastian Cappeta
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Brandon Chin
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Isabella Hamdan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Annelise Hamer
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Rachel Hyzny
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Andrew Karp
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Daniel Lee
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Alexandria Lim
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Medha Nayak
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Vishnu Palaniappan
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Soomin Park
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sarika Satishkumar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Anika Seth
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Uva Sri Dasari
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Emili Toppari
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ayush Vyas
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Julianne Walker
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Evan Weston
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Atif Zafar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Cecelia Zielke
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ganapati H Mahabeleshwar
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Alan M Tartakoff
- Pathology Department and The Cell Biology Program, Case Western Reserve University, Cleveland, OH 44106, USA
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3
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Cheung MH, Amin A, Wu R, Qin Y, Zou L, Yu Z, Liang C. Human NOC3 is essential for DNA replication licensing in human cells. Cell Cycle 2019; 18:605-620. [PMID: 30741601 DOI: 10.1080/15384101.2019.1578522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Noc3p (Nucleolar Complex-associated protein) is an essential protein in budding yeast DNA replication licensing. Noc3p mediates the loading of Cdc6p and MCM proteins onto replication origins during the M-to-G1 transition by interacting with ORC (Origin Recognition Complex) and MCM (Minichromosome Maintenance) proteins. FAD24 (Factor for Adipocyte Differentiation, clone number 24), the human homolog of Noc3p (hNOC3), was previously reported to play roles in the regulation of DNA replication and proliferation in human cells. However, the role of hNOC3 in replication licensing was unclear. Here we report that hNOC3 physically interacts with multiple human pre-replicative complex (pre-RC) proteins and associates with known replication origins throughout the cell cycle. Moreover, knockdown of hNOC3 in HeLa cells abrogates the chromatin association of other pre-RC proteins including hCDC6 and hMCM, leading to DNA replication defects and eventual apoptosis in an abortive S-phase. In comparison, specific inhibition of the ribosome biogenesis pathway by preventing pre-rRNA synthesis, does not lead to any cell cycle or DNA replication defect or apoptosis in the same timeframe as the hNOC3 knockdown experiments. Our findings strongly suggest that hNOC3 plays an essential role in pre-RC formation and the initiation of DNA replication independent of its potential role in ribosome biogenesis in human cells.
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Affiliation(s)
- Man-Hei Cheung
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,b Guangzhou HKUST Fok Ying Tung Research Institute , Guangzhou , China.,c Shenzhen-PKU-HKUST Medical Center , Biomedical Research Institute , Shenzhen , China
| | - Aftab Amin
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,b Guangzhou HKUST Fok Ying Tung Research Institute , Guangzhou , China.,d School of Chinese Medicine , Hong Kong Baptist University , Hong Kong , China
| | - Rentian Wu
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China
| | - Yan Qin
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China
| | - Lan Zou
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,e Intelgen Limited , Hong Kong-Guangzhou-Foshan , China
| | - Zhiling Yu
- d School of Chinese Medicine , Hong Kong Baptist University , Hong Kong , China
| | - Chun Liang
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,b Guangzhou HKUST Fok Ying Tung Research Institute , Guangzhou , China.,c Shenzhen-PKU-HKUST Medical Center , Biomedical Research Institute , Shenzhen , China.,e Intelgen Limited , Hong Kong-Guangzhou-Foshan , China
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4
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Qin Y, Li H, Jia L, Yan J, Gao GF, Li X. Targeted disruption of Noc4l leads to preimplantation embryonic lethality in mice. Protein Cell 2018; 8:230-235. [PMID: 28012024 PMCID: PMC5326621 DOI: 10.1007/s13238-016-0335-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Yongli Qin
- State Key Laboratory of the Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Haifeng Li
- State Key Laboratory of the Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Lina Jia
- State Key Laboratory of the Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Jinghua Yan
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - George Fu Gao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Xiangdong Li
- State Key Laboratory of the Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
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5
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Lebaron S, Segerstolpe A, French SL, Dudnakova T, de Lima Alves F, Granneman S, Rappsilber J, Beyer AL, Wieslander L, Tollervey D. Rrp5 binding at multiple sites coordinates pre-rRNA processing and assembly. Mol Cell 2013; 52:707-19. [PMID: 24239293 PMCID: PMC3991325 DOI: 10.1016/j.molcel.2013.10.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/27/2013] [Accepted: 10/08/2013] [Indexed: 01/01/2023]
Abstract
In vivo UV crosslinking identified numerous preribosomal RNA (pre-rRNA) binding sites for the large, highly conserved ribosome synthesis factor Rrp5. Intramolecular complementation has shown that the C-terminal domain (CTD) of Rrp5 is required for pre-rRNA cleavage at sites A0–A2 on the pathway of 18S rRNA synthesis, whereas the N-terminal domain (NTD) is required for A3 cleavage on the pathway of 5.8S/25S rRNA synthesis. The CTD was crosslinked to sequences flanking A2 and to the snoRNAs U3, U14, snR30, and snR10, which are required for cleavage at A0–A2. The NTD was crosslinked to sequences flanking A3 and to the RNA component of ribonuclease MRP, which cleaves site A3. Rrp5 could also be directly crosslinked to several large structural proteins and nucleoside triphosphatases. A key role in coordinating preribosomal assembly and processing was confirmed by chromatin spreads. Following depletion of Rrp5, cotranscriptional cleavage was lost and preribosome compaction greatly reduced. Rrp5 binds multiple dispersed sites in the pre-rRNA The NTD and CTD of Rrp5 each bind adjacent to sites of cleavages that require them Rrp5 directly binds large, structural proteins and NTPases Rrp5 is required for preribosome compaction
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Affiliation(s)
- Simon Lebaron
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland
| | - Asa Segerstolpe
- Department of Molecular Biosciences, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Sarah L French
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908-0734, USA
| | - Tatiana Dudnakova
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland
| | - Flavia de Lima Alves
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland
| | - Sander Granneman
- SynthSys, JR Waddington Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland
| | - Ann L Beyer
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908-0734, USA
| | - Lars Wieslander
- Department of Molecular Biosciences, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland.
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6
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Cheng M, Yang H, Long H, Zhang Y, Chen X, Yang Z, Lei T. Molecular characterization and transcriptional analysis of fad24 in pigs. Gene 2012; 503:208-14. [DOI: 10.1016/j.gene.2012.04.087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 03/26/2012] [Accepted: 04/27/2012] [Indexed: 01/10/2023]
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7
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Kühn H, Hierlmeier T, Merl J, Jakob S, Aguissa-Touré AH, Milkereit P, Tschochner H. The Noc-domain containing C-terminus of Noc4p mediates both formation of the Noc4p-Nop14p submodule and its incorporation into the SSU processome. PLoS One 2009; 4:e8370. [PMID: 20019888 PMCID: PMC2794458 DOI: 10.1371/journal.pone.0008370] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 11/27/2009] [Indexed: 11/23/2022] Open
Abstract
Noc1p, Noc3p and Noc4p are eukaryotic proteins which play essential roles in yeast ribosome biogenesis and contain a homologous stretch of about 45 aminoacids (Noc-domain) of unknown function. Yeast Noc4p is a component of the small ribosomal subunit (SSU) processome, can be isolated as a stable Noc4p-Nop14p SSU-processome submodule from yeast cells, and is required for nuclear steps of small ribosomal subunit rRNA maturation. We expressed a series of mutated alleles of NOC4 in yeast cells and analysed whether the corresponding protein variants support vegetative growth, interact with Nop14p, and are incorporated into the SSU-processome. The data reveal that the essential C-terminus of Noc4p which contains 237 aminoacids including the Noc-domain represents a protein-protein interaction module. It is required and sufficient for its association with Nop14p and several nuclear precursors of the small ribosomal subunit. The N-terminal Noc4-part seems to be targeted to pre-ribosomes via the C-terminus of Noc4p and plays there an essential role in SSU-processome function. Replacement of the Noc4p-Noc-domain by its homologues Noc1p-counterpart results in a hybrid Noc4p variant which fails to associate with Nop14p and pre-ribosomes. On the other hand, exchange of 6 amino acids in the Noc1-Noc-domain of this hybrid Noc4p protein is sufficient to restore its essential in vivo functions. These data suggest that Noc-domains of Noc1p and Noc4p share a common structural backbone in which diverging amino acids play crucial roles in mediating specific regulated interactions. Our analysis allows us to distinguish between different functions of certain domains within Noc4p and contribute to the understanding of how incorporation of Noc4p into ribosomal precursors is coupled to rRNA processing and maturation of the small ribosomal subunit.
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Affiliation(s)
- Holger Kühn
- Institut für Biochemie, Genetik und Mikrobiologie, University of Regensburg, Regensburg, Germany
| | - Thomas Hierlmeier
- Institut für Biochemie, Genetik und Mikrobiologie, University of Regensburg, Regensburg, Germany
| | - Juliane Merl
- Institut für Biochemie, Genetik und Mikrobiologie, University of Regensburg, Regensburg, Germany
| | - Steffen Jakob
- Institut für Biochemie, Genetik und Mikrobiologie, University of Regensburg, Regensburg, Germany
| | | | - Philipp Milkereit
- Institut für Biochemie, Genetik und Mikrobiologie, University of Regensburg, Regensburg, Germany
- * E-mail: (PM); (HT)
| | - Herbert Tschochner
- Institut für Biochemie, Genetik und Mikrobiologie, University of Regensburg, Regensburg, Germany
- * E-mail: (PM); (HT)
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8
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Li N, Yuan L, Liu N, Shi D, Li X, Tang Z, Liu J, Sundaresan V, Yang WC. SLOW WALKER2, a NOC1/MAK21 homologue, is essential for coordinated cell cycle progression during female gametophyte development in Arabidopsis. PLANT PHYSIOLOGY 2009; 151:1486-97. [PMID: 19734265 PMCID: PMC2773048 DOI: 10.1104/pp.109.142414] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Accepted: 08/30/2009] [Indexed: 05/19/2023]
Abstract
Morphogenesis requires the coordination of cell growth, division, and cell differentiation. Female gametogenesis in flowering plants, where a single haploid spore undergoes continuous growth and nuclear division without cytokinesis to form an eight-nucleate coenocytic embryo sac before cellularization, provides a good system to study the genetic control of such processes in multicellular organisms. Here, we report the characterization of an Arabidopsis (Arabidopsis thaliana) female gametophyte mutant, slow walker2 (swa2), in which the progression of the mitotic cycles and the synchrony of female gametophyte development were impaired, causing an arrest of female gametophytes at the two-, four-, or eight-nucleate stage. Delayed pollination test showed that a portion of the mutant ovules were able to develop into functional embryo sacs and could be fertilized. SWA2 encodes a nucleolar protein homologous to yeast NUCLEOLAR COMPLEX ASSOCIATED PROTEIN1 (NOC1)/MAINTENANCE OF KILLER21 that, together with NOC2, is involved in preribosome export from the nucleus to the cytoplasm. Similarly, SWA2 can physically interact with a putative Arabidopsis NOC2 homologue. SWA2 is expressed ubiquitously throughout the plant, at high levels in actively dividing tissues and gametophytes. Therefore, we conclude that SWA2 most likely plays a role in ribosome biogenesis that is essential for the coordinated mitotic progression of the female gametophyte.
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9
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Dez C, Dlakić M, Tollervey D. Roles of the HEAT repeat proteins Utp10 and Utp20 in 40S ribosome maturation. RNA (NEW YORK, N.Y.) 2007; 13:1516-27. [PMID: 17652137 PMCID: PMC1950751 DOI: 10.1261/rna.609807] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A family of HEAT-repeat containing ribosome synthesis factors was previously identified in Saccharomyces cerevisiae. We report the detailed characterization of two of these factors, Utp10 and Utp20, which were initially identified as components of the small subunit processome. Coprecipitation analyses confirmed the association of Utp10 and Utp20 with U3 snoRNA and the early pre-rRNA processing intermediates. Particularly strong association was seen with aberrant processing intermediates, which may help target these RNAs for degradation. Genetic depletion of either protein inhibited the early pre-rRNA processing steps in 18S rRNA maturation but had little effect on pre-rRNA transcription or synthesis of the 25S or 5.8S rRNAs. The absence of the poly(A) polymerase Trf5, a component of the TRAMP5 complex and exosome cofactor, led to stabilization of the aberrant 23S RNA in strains depleted of Utp10 or Utp20. In the case of Utp10, 20S pre-rRNA synthesis was also modestly increased by this loss of surveillance activity.
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MESH Headings
- Models, Molecular
- RNA Processing, Post-Transcriptional/physiology
- RNA, Ribosomal, 18S/biosynthesis
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/physiology
- Repetitive Sequences, Amino Acid
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/physiology
- Ribonucleoproteins, Small Nucleolar/genetics
- Ribonucleoproteins, Small Nucleolar/physiology
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/growth & development
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/physiology
- Signal Transduction/genetics
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Affiliation(s)
- Christophe Dez
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Scotland
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10
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Dez C, Houseley J, Tollervey D. Surveillance of nuclear-restricted pre-ribosomes within a subnucleolar region of Saccharomyces cerevisiae. EMBO J 2006; 25:1534-46. [PMID: 16541108 PMCID: PMC1440318 DOI: 10.1038/sj.emboj.7601035] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Accepted: 02/14/2006] [Indexed: 11/09/2022] Open
Abstract
We previously hypothesized that HEAT-repeat (Huntington, elongation A subunit, TOR) ribosome synthesis factors function in ribosome export. We report that the HEAT-repeat protein Sda1p is a component of late 60S pre-ribosomes and is required for nuclear export of both ribosomal subunits. In strains carrying the ts-lethal sda1-2 mutation, pre-60S particles were rapidly degraded following transfer to 37 degrees C. Polyadenylated forms of the 27S pre-rRNA and the 25S rRNA were detected, suggesting the involvement of the Trf4p/Air/Mtr4p polyadenylation complex (TRAMP). The absence of Trf4p suppressed polyadenylation and stabilized the pre-rRNA and rRNA. The absence of the nuclear exosome component Rrp6p also conferred RNA stabilization, with some hyperadenylation. We conclude that the nuclear-restricted pre-ribosomes are polyadenylated by TRAMP and degraded by the exosome. In sda1-2 strains at 37 degrees C, pre-40S and pre-60S ribosomes initially accumulated in the nucleoplasm, but then strongly concentrated in a subnucleolar focus, together with exosome and TRAMP components. Localization of pre-ribosomes to this focus was lost in sda1-2 strains lacking Trf4p or Rrp6p. We designate this nucleolar focus the No-body and propose that it represents a site of pre-ribosome surveillance.
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Affiliation(s)
- Christophe Dez
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Jonathan Houseley
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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11
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Abstract
The 26S proteasome is responsible for regulated proteolysis of most intracellular proteins yet the focus of intense regulatory action itself. Proteasome abundance is responsive to cell needs or stress conditions, and dynamically localized to concentrations of substrates. Proteasomes are continually assembled and disassembled, and their subunits subject to a variety of posttranslational modifications. Furthermore, as robust and multi-tasking as this complex is, it does not function alone. A spattering of closely associating proteins enhances complex stability, fine-tunes activity, assists in substrate-binding, recycling of ubiquitin, and more. HEAT repeat caps activate proteasomes, yet share remarkable features with nuclear importins. Fascinating cross talk even occurs with ribosomes through common maturation factors. The dynamics of proteasome configurations and how they relate to diverse activities is the topic of this review.
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Affiliation(s)
- Michael H Glickman
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
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12
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Fatica A, Tollervey D, Dlakić M. PIN domain of Nob1p is required for D-site cleavage in 20S pre-rRNA. RNA (NEW YORK, N.Y.) 2004; 10:1698-701. [PMID: 15388878 PMCID: PMC1370656 DOI: 10.1261/rna.7123504] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Accepted: 08/18/2004] [Indexed: 05/18/2023]
Abstract
Nob1p (Yor056c) is essential for processing of the 20S pre-rRNA to the mature 18S rRNA. It is part of a pre-40S ribosomal particle that is transported to the cytoplasm and subsequently cleaved at the 3' end of mature 18S rRNA (D-site). Nob1p is also reported to participate in proteasome biogenesis, and it was therefore unclear whether its primary activity is in ribosome synthesis. In this work, we describe a homology model of the PIN domain of Nob1p, which structurally mimics Mg(2+)-dependent exonucleases despite negligible similarity in primary sequence. Insights gained from this model were used to design a point mutation that was predicted to abolish the postulated enzymatic activity. Cells expressing Nob1p with this mutation failed to cleave the 20S pre-rRNA. This supports both the significance of the structural model and the idea that Nob1p is the long-sought D-site endonuclease.
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Affiliation(s)
- Alessandro Fatica
- Department of Genetics and Molecular Biology, University of Rome "La Sapienza", Rome, Italy
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