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Johnson DL, Kumar R, Kakhniashvili D, Pfeffer LM, Laribee RN. Ccr4-not ubiquitin ligase signaling regulates ribosomal protein homeostasis and inhibits 40S ribosomal autophagy. J Biol Chem 2024; 300:107582. [PMID: 39025453 DOI: 10.1016/j.jbc.2024.107582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 06/27/2024] [Accepted: 07/10/2024] [Indexed: 07/20/2024] Open
Abstract
The Ccr4-Not complex contains the poorly understood Not4 ubiquitin ligase that functions in transcription, mRNA decay, translation, proteostasis, and endolysosomal nutrient signaling. To gain further insight into the in vivo functions of the ligase, we performed quantitative proteomics in Saccharomyces cerevisiae using yeast cells lacking Not4, or cells overexpressing wild-type Not4 or an inactive Not4 mutant. Herein, we provide evidence that balanced Not4 activity maintains ribosomal protein (RP) homeostasis independent of changes to RP mRNA or known Not4 ribosomal substrates. Intriguingly, we also find that Not4 loss activates 40S ribosomal autophagy independently of canonical Atg7-dependent macroautophagy, indicating that microautophagy is responsible. We previously demonstrated that Ccr4-Not stimulates the target of rapamycin complex 1 (TORC1) signaling, which activates RP expression and inhibits autophagy, by maintaining vacuole V-ATPase H+ pump activity. Importantly, combining Not4 deficient cells with a mutant that blocks vacuole H+ export fully restores RP expression and increases 40S RP autophagy efficiency. In contrast, restoring TORC1 activity alone fails to rescue either process, indicating that Not4 loss disrupts additional endolysosomal functions that regulate RP expression and 40S autophagy. Analysis of the Not4-regulated proteome reveals increases in endolysosomal and autophagy-related factors that functionally interact with Not4 to control RP expression and affect 40S autophagy. Collectively, our data indicate that balanced Ccr4-Not ubiquitin ligase signaling maintains RP homeostasis and inhibits 40S autophagy via the ligase's emerging role as an endolysosomal regulator.
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Affiliation(s)
- Daniel L Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Ravinder Kumar
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - David Kakhniashvili
- Proteomics and Metabolomics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Lawrence M Pfeffer
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - R Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
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2
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Johnson DL, Kumar R, Kakhniashvili D, Pfeffer LM, Laribee RN. Ccr4-Not ubiquitin ligase signaling regulates ribosomal protein homeostasis and inhibits 40S ribosomal autophagy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555095. [PMID: 37693548 PMCID: PMC10491097 DOI: 10.1101/2023.08.28.555095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The Ccr4-Not complex containing the Not4 ubiquitin ligase regulates gene transcription and mRNA decay, yet it also has poorly defined roles in translation, proteostasis, and endolysosomal-dependent nutrient signaling. To define how Ccr4-Not mediated ubiquitin signaling regulates these additional processes, we performed quantitative proteomics in the yeast Saccharomyces cerevisiae lacking the Not4 ubiquitin ligase, and also in cells overexpressing either wild-type or functionally inactive ligase. Herein, we provide evidence that both increased and decreased Ccr4-Not ubiquitin signaling disrupts ribosomal protein (RP) homeostasis independently of reduced RP mRNA changes or reductions in known Not4 ribosomal substrates. Surprisingly, we also find that both Not4-mediated ubiquitin signaling, and the Ccr4 subunit, actively inhibit 40S ribosomal autophagy. This 40S autophagy is independent of canonical Atg7-dependent macroautophagy, thus indicating microautophagy activation is responsible. Furthermore, the Not4 ligase genetically interacts with endolysosomal pathway effectors to control both RP expression and 40S autophagy efficiency. Overall, we demonstrate that balanced Ccr4-Not ligase activity maintains RP homeostasis, and that Ccr4-Not ubiquitin signaling interacts with the endolysosomal pathway to both regulate RP expression and inhibit 40S ribosomal autophagy.
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Affiliation(s)
- Daniel L. Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Ravinder Kumar
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - David Kakhniashvili
- Proteomics and Metabolomics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Lawrence M. Pfeffer
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
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3
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Eyboulet F, Jeronimo C, Côté J, Robert F. The deubiquitylase Ubp15 couples transcription to mRNA export. eLife 2020; 9:e61264. [PMID: 33226341 PMCID: PMC7682988 DOI: 10.7554/elife.61264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/04/2020] [Indexed: 12/16/2022] Open
Abstract
Nuclear export of messenger RNAs (mRNAs) is intimately coupled to their synthesis. pre-mRNAs assemble into dynamic ribonucleoparticles as they are being transcribed, processed, and exported. The role of ubiquitylation in this process is increasingly recognized but, while a few E3 ligases have been shown to regulate nuclear export, evidence for deubiquitylases is currently lacking. Here we identified deubiquitylase Ubp15 as a regulator of nuclear export in Saccharomyces cerevisiae. Ubp15 interacts with both RNA polymerase II and the nuclear pore complex, and its deletion reverts the nuclear export defect of E3 ligase Rsp5 mutants. The deletion of UBP15 leads to hyper-ubiquitylation of the main nuclear export receptor Mex67 and affects its association with THO, a complex coupling transcription to mRNA processing and involved in the recruitment of mRNA export factors to nascent transcripts. Collectively, our data support a role for Ubp15 in coupling transcription to mRNA export.
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Affiliation(s)
- Fanny Eyboulet
- Institut de recherches cliniques de MontréalMontréalCanada
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center, Axe Oncologie du Centre de Recherche du CHU de Québec-Université LavalQuébec CityCanada
| | - Célia Jeronimo
- Institut de recherches cliniques de MontréalMontréalCanada
| | - Jacques Côté
- St-Patrick Research Group in Basic Oncology, Laval University Cancer Research Center, Axe Oncologie du Centre de Recherche du CHU de Québec-Université LavalQuébec CityCanada
| | - François Robert
- Institut de recherches cliniques de MontréalMontréalCanada
- Département de Médecine, Faculté de Médecine, Université de MontréalMontréalCanada
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4
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An F-Box Protein, Mdm30, Interacts with TREX Subunit Sub2 To Regulate Cellular Abundance Cotranscriptionally in Orchestrating mRNA Export Independently of Splicing and Mitochondrial Function. Mol Cell Biol 2020; 40:MCB.00570-19. [PMID: 31932480 DOI: 10.1128/mcb.00570-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/03/2020] [Indexed: 02/02/2023] Open
Abstract
Although an F-box protein, Mdm30, is found to regulate ubiquitylation of the Sub2 component of TREX (transcription-export) complex for proteasomal degradation in stimulation of mRNA export, it remains unknown whether such ubiquitin-proteasome system (UPS) regulation of Sub2 occurs cotranscriptionally via its interaction with Mdm30. Further, it is unclear whether impaired UPS regulation of Sub2 in the absence of Mdm30 alters mRNA export via splicing defects of export factors and/or mitochondrial dynamics/function, since Sub2 controls mRNA splicing and Mdm30 regulates mitochondrial aggregation. Here, we show that Mdm30 interacts with Sub2, and temporary shutdown of Mdm30 enhances Sub2's abundance and impairs mRNA export. Likewise, Sub2's abundance is increased following transcriptional inhibition. These results support Mdm30's direct role in regulation of Sub2's cellular abundance in a transcription-dependent manner. Consistently, the chromatin-bound Sub2 level is increased in the absence of Mdm30. Further, we find that Mdm30 does not facilitate splicing of export factors. Moreover, Mdm30 does not have a dramatic effect on mitochondrial respiration/function, and mRNA export occurs in the absence of Fzo1, which is required for mitochondrial dynamics/respiration. Collective results reveal that Mdm30 interacts with Sub2 for proteasomal degradation in a transcription-dependent manner to promote mRNA export independently of splicing or mitochondrial function, thus advancing our understanding of mRNA export.
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5
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Xu J, Sheng Z, Li F, Wang S, Yuan Y, Wang M, Yu Z. NEDD4 protects vascular endothelial cells against Angiotensin II-induced cell death via enhancement of XPO1-mediated nuclear export. Exp Cell Res 2019; 383:111505. [PMID: 31326389 DOI: 10.1016/j.yexcr.2019.111505] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/14/2019] [Accepted: 07/18/2019] [Indexed: 01/11/2023]
Abstract
NEDD4 is an E3 ubiquitin ligase containing the HECT domain, which regulates various cellular processes, but its role in vascular endothelial cells is unknown. In the present study, we found that NEDD4 bound directly to XPO1 by co-immunoprecipitation screening. In HUVECs (human umbilical vein endothelial cells), overexpression of NEDD4 reduced Ang II-induced ROS level and cell apoptosis. Ang II stimulation led to nuclear accumulation of cargoes, while overexpression of NEDD4 enhanced the XPO1-dependent nuclear export of its cargoes. KPT185, an inhibitor of XPO1, can abolished the protective effect of NEDD4 under Ang II treatment. In addition, NEDD4 could promote the interaction between XPO1 and RanBP3 via K63-linked ubiquitination of XPO1. These results suggested that NEDD4 played a protective role in vascular endothelial cell injury through regulating XPO1-mediated nuclear export.
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Affiliation(s)
- Jianning Xu
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Zhiyong Sheng
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Fuxin Li
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Shu Wang
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Ying Yuan
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Meng Wang
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Zhihong Yu
- Intensive Care Unit, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China.
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6
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Domanska A, Kaminska J. Role of Rsp5 ubiquitin ligase in biogenesis of rRNA, mRNA and tRNA in yeast. RNA Biol 2016; 12:1265-74. [PMID: 26403176 DOI: 10.1080/15476286.2015.1094604] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Rsp5 ubiquitin ligase is required for ubiquitination of a wide variety of proteins involved in essential processes. Rsp5 was shown to be involved in regulation of lipid biosynthesis, intracellular trafficking of proteins, response to various stresses, and many other processes. In this article, we provide a comprehensive review of the nuclear and cytoplasmic functions of Rsp5 with a focus on biogenesis of different RNAs. We also briefly describe the participation of Rsp5 in the regulation of the RNA polymerase II complex, and its potential role in the regulation of other RNA polymerases. Moreover, we emphasize the function of Rsp5 in the coordination of the different steps of rRNA, mRNA and tRNA metabolism in the context of protein biosynthesis. Finally, we highlight the involvement of Rsp5 in controlling diverse cellular mechanisms at multiple levels and in adaptation of the cell to changing growth conditions.
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Affiliation(s)
- Anna Domanska
- a Institute of Biochemistry and Biophysics, Polish Academy of Sciences ; Warsaw , Poland
| | - Joanna Kaminska
- a Institute of Biochemistry and Biophysics, Polish Academy of Sciences ; Warsaw , Poland
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7
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Deubiquitinase activity is required for the proteasomal degradation of misfolded cytosolic proteins upon heat-stress. Nat Commun 2016; 7:12907. [PMID: 27698423 PMCID: PMC5059457 DOI: 10.1038/ncomms12907] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 08/12/2016] [Indexed: 12/25/2022] Open
Abstract
Elimination of misfolded proteins is crucial for proteostasis and to prevent proteinopathies. Nedd4/Rsp5 emerged as a major E3-ligase involved in multiple quality control pathways that target misfolded plasma membrane proteins, aggregated polypeptides and cytosolic heat-induced misfolded proteins for degradation. It remained unclear how in one case cytosolic heat-induced Rsp5 substrates are destined for proteasomal degradation, whereas other Rsp5 quality control substrates are otherwise directed to lysosomal degradation. Here we find that Ubp2 and Ubp3 deubiquitinases are required for the proteasomal degradation of cytosolic misfolded proteins targeted by Rsp5 after heat-shock (HS). The two deubiquitinases associate more with Rsp5 upon heat-stress to prevent the assembly of K63-linked ubiquitin on Rsp5 heat-induced substrates. This activity was required to promote the K48-mediated proteasomal degradation of Rsp5 HS-induced substrates. Our results indicate that ubiquitin chain editing is key to the cytosolic protein quality control under stress conditions. Ubiquitination of misfolded proteins usually results in protein degradation. Here, the authors show that two deubiquitinases—enzymes that remove ubiquitin—are required for the proteasomal degradation of misfolded proteins in response to heat-shock in yeast.
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8
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Paul B, Montpetit B. Altered RNA processing and export lead to retention of mRNAs near transcription sites and nuclear pore complexes or within the nucleolus. Mol Biol Cell 2016; 27:2742-56. [PMID: 27385342 PMCID: PMC5007094 DOI: 10.1091/mbc.e16-04-0244] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/29/2016] [Indexed: 01/17/2023] Open
Abstract
In a screen of >1000 essential gene mutants in Saccharomyces cerevisiae, 26 mutants are found that directly or indirectly affect mRNA processing and/or mRNA export. Single-molecule FISH data show that the majority of these mutants retain mRNAs at discrete locations within the nucleus, which include the nucleolus. Many protein factors are required for mRNA biogenesis and nuclear export, which are central to the eukaryotic gene expression program. It is unclear, however, whether all factors have been identified. Here we report on a screen of >1000 essential gene mutants in Saccharomyces cerevisiae for defects in mRNA processing and export, identifying 26 mutants with defects in this process. Single-molecule FISH data showed that the majority of these mutants accumulated mRNA within specific regions of the nucleus, which included 1) mRNAs within the nucleolus when nucleocytoplasmic transport, rRNA biogenesis, or RNA processing and surveillance was disrupted, 2) the buildup of mRNAs near transcription sites in 3′-end processing and chromosome segregation mutants, and 3) transcripts being enriched near nuclear pore complexes when components of the mRNA export machinery were mutated. These data show that alterations to various nuclear processes lead to the retention of mRNAs at discrete locations within the nucleus.
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Affiliation(s)
- Biplab Paul
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ben Montpetit
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
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9
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Fang NN, Chan GT, Zhu M, Comyn SA, Persaud A, Deshaies RJ, Rotin D, Gsponer J, Mayor T. Rsp5/Nedd4 is the main ubiquitin ligase that targets cytosolic misfolded proteins following heat stress. Nat Cell Biol 2014; 16:1227-37. [PMID: 25344756 PMCID: PMC5224936 DOI: 10.1038/ncb3054] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 09/17/2014] [Indexed: 12/14/2022]
Abstract
The heat-shock response is a complex cellular program that induces major changes in protein translation, folding and degradation to alleviate toxicity caused by protein misfolding. Although heat shock has been widely used to study proteostasis, it remained unclear how misfolded proteins are targeted for proteolysis in these conditions. We found that Rsp5 and its mammalian homologue Nedd4 are important E3 ligases responsible for the increased ubiquitylation induced by heat stress. We determined that Rsp5 ubiquitylates mainly cytosolic misfolded proteins upon heat shock for proteasome degradation. We found that ubiquitylation of heat-induced substrates requires the Hsp40 co-chaperone Ydj1 that is further associated with Rsp5 upon heat shock. In addition, ubiquitylation is also promoted by PY Rsp5-binding motifs found primarily in the structured regions of stress-induced substrates, which can act as heat-induced degrons. Our results support a bipartite recognition mechanism combining direct and chaperone-dependent ubiquitylation of misfolded cytosolic proteins by Rsp5.
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Affiliation(s)
- Nancy N Fang
- Department of Biochemistry and Molecular Biology, Centre for High-Throughput Biology, University of British Columbia, 2125 East Mall Vancouver, British Columbia V6T1Z4, Canada
| | - Gerard T Chan
- Department of Biochemistry and Molecular Biology, Centre for High-Throughput Biology, University of British Columbia, 2125 East Mall Vancouver, British Columbia V6T1Z4, Canada
| | - Mang Zhu
- Department of Biochemistry and Molecular Biology, Centre for High-Throughput Biology, University of British Columbia, 2125 East Mall Vancouver, British Columbia V6T1Z4, Canada
| | - Sophie A Comyn
- Department of Biochemistry and Molecular Biology, Centre for High-Throughput Biology, University of British Columbia, 2125 East Mall Vancouver, British Columbia V6T1Z4, Canada
| | - Avinash Persaud
- Program in Cell Biology, Hospital for Sick Children, and Biochemistry Department, University of Toronto, Toronto, Ontario M5G 0A4, Canada
| | - Raymond J Deshaies
- Howard Hughes Medical Institute, Division of Biology and Biological Engineering, 114-96 Caltech, 1200 E. California Boulevard Pasadena, California 91125, USA
| | - Daniela Rotin
- Program in Cell Biology, Hospital for Sick Children, and Biochemistry Department, University of Toronto, Toronto, Ontario M5G 0A4, Canada
| | - Joerg Gsponer
- Department of Biochemistry and Molecular Biology, Centre for High-Throughput Biology, University of British Columbia, 2125 East Mall Vancouver, British Columbia V6T1Z4, Canada
| | - Thibault Mayor
- Department of Biochemistry and Molecular Biology, Centre for High-Throughput Biology, University of British Columbia, 2125 East Mall Vancouver, British Columbia V6T1Z4, Canada
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10
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Durairaj G, Lahudkar S, Bhaumik SR. A new regulatory pathway of mRNA export by an F-box protein, Mdm30. RNA (NEW YORK, N.Y.) 2014; 20:133-42. [PMID: 24327750 PMCID: PMC3895266 DOI: 10.1261/rna.042325.113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Mdm30, an F-box protein in yeast, has been recently shown to promote mRNA export. However, it remains unknown how Mdm30 facilitates mRNA export. Here, we show that Mdm30 targets the Sub2 component of the TREX (Transcription/Export) complex for ubiquitylation and subsequent proteasomal degradation. Such a targeted degradation of Sub2 enhances the recruitment of the mRNA export adaptor, Yra1, to the active genes to promote mRNA export. Together, these results elucidate that Mdm30 promotes mRNA export by lowering Sub2's stability and consequently enhancing Yra1 recruitment, thus illuminating new regulatory mechanisms of mRNA export by Mdm30.
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11
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Mulet JM, Llopis-Torregrosa V, Primo C, Marqués MC, Yenush L. Endocytic regulation of alkali metal transport proteins in mammals, yeast and plants. Curr Genet 2013; 59:207-30. [PMID: 23974285 DOI: 10.1007/s00294-013-0401-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/24/2013] [Accepted: 07/29/2013] [Indexed: 12/30/2022]
Abstract
The relative concentrations of ions and solutes inside cells are actively maintained by several classes of transport proteins, in many cases against their concentration gradient. These transport processes, which consume a large portion of cellular energy, must be constantly regulated. Many structurally distinct families of channels, carriers, and pumps have been characterized in considerable detail during the past decades and defects in the function of some of these proteins have been linked to a growing list of human diseases. The dynamic regulation of the transport proteins present at the cell surface is vital for both normal cellular function and for the successful adaptation to changing environments. The composition of proteins present at the cell surface is controlled on both the transcriptional and post-translational level. Post-translational regulation involves highly conserved mechanisms of phosphorylation- and ubiquitylation-dependent signal transduction routes used to modify the cohort of receptors and transport proteins present under any given circumstances. In this review, we will summarize what is currently known about one facet of this regulatory process: the endocytic regulation of alkali metal transport proteins. The physiological relevance, major contributors, parallels and missing pieces of the puzzle in mammals, yeast and plants will be discussed.
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Affiliation(s)
- José Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, 46022, Valencia, Spain
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12
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Chanarat S, Sträßer K. Splicing and beyond: the many faces of the Prp19 complex. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2126-34. [PMID: 23742842 DOI: 10.1016/j.bbamcr.2013.05.023] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 05/22/2013] [Accepted: 05/24/2013] [Indexed: 12/18/2022]
Abstract
The conserved Prp19 complex (Prp19C) - also known as NineTeen Complex (NTC) - functions in several processes of paramount importance for cellular homeostasis. NTC/Prp19C was discovered as a complex that functions in splicing and more specifically during the catalytic activation of the spliceosome. More recent work revealed that NTC/Prp19C plays a role in transcription elongation in Saccharomyces cerevisiae and in genome maintenance in higher eukaryotes. In addition, mouse PRP19 might ubiquity late proteins targeted for degradation and guide them to the proteasome. Furthermore, NTC/Prp19C has been implicated in lipid droplet biogenesis. In the future, the molecular function of NTC/Prp19C in all of these processes needs to be refined or elucidated. Most of NTC/Prp19C's functions have been shown in only one or few organisms. However, since this complex is highly conserved it is likely that it has the same functions across all species. Moreover, one NTC/Prp19C or different subcomplexes could function in the above-mentioned processes. Intriguingly, NTC/Prp19C might link these different processes to ensure an optimal coordination of cellular processes. Thus, many important questions about the functions of this interesting complex remain to be investigated. In this review we discuss the different functions of NTC/Prp19C focusing on the novel and emerging ones as well as open questions.
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Affiliation(s)
- Sittinan Chanarat
- Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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13
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Ryšlavá H, Doubnerová V, Kavan D, Vaněk O. Effect of posttranslational modifications on enzyme function and assembly. J Proteomics 2013; 92:80-109. [PMID: 23603109 DOI: 10.1016/j.jprot.2013.03.025] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 03/01/2013] [Accepted: 03/11/2013] [Indexed: 12/22/2022]
Abstract
The detailed examination of enzyme molecules by mass spectrometry and other techniques continues to identify hundreds of distinct PTMs. Recently, global analyses of enzymes using methods of contemporary proteomics revealed widespread distribution of PTMs on many key enzymes distributed in all cellular compartments. Critically, patterns of multiple enzymatic and nonenzymatic PTMs within a single enzyme are now functionally evaluated providing a holistic picture of a macromolecule interacting with low molecular mass compounds, some of them being substrates, enzyme regulators, or activated precursors for enzymatic and nonenzymatic PTMs. Multiple PTMs within a single enzyme molecule and their mutual interplays are critical for the regulation of catalytic activity. Full understanding of this regulation will require detailed structural investigation of enzymes, their structural analogs, and their complexes. Further, proteomics is now integrated with molecular genetics, transcriptomics, and other areas leading to systems biology strategies. These allow the functional interrogation of complex enzymatic networks in their natural environment. In the future, one might envisage the use of robust high throughput analytical techniques that will be able to detect multiple PTMs on a global scale of individual proteomes from a number of carefully selected cells and cellular compartments. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Helena Ryšlavá
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, CZ-12840 Prague 2, Czech Republic.
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14
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Finley D, Ulrich HD, Sommer T, Kaiser P. The ubiquitin-proteasome system of Saccharomyces cerevisiae. Genetics 2012; 192:319-60. [PMID: 23028185 PMCID: PMC3454868 DOI: 10.1534/genetics.112.140467] [Citation(s) in RCA: 301] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 07/28/2012] [Indexed: 12/14/2022] Open
Abstract
Protein modifications provide cells with exquisite temporal and spatial control of protein function. Ubiquitin is among the most important modifiers, serving both to target hundreds of proteins for rapid degradation by the proteasome, and as a dynamic signaling agent that regulates the function of covalently bound proteins. The diverse effects of ubiquitylation reflect the assembly of structurally distinct ubiquitin chains on target proteins. The resulting ubiquitin code is interpreted by an extensive family of ubiquitin receptors. Here we review the components of this regulatory network and its effects throughout the cell.
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Affiliation(s)
- Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Helle D. Ulrich
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, EN6 3LD, United Kingdom
| | - Thomas Sommer
- Max-Delbrück Center for Molecular Medicine, 13125 Berlin, Germany
| | - Peter Kaiser
- Department of Biological Chemistry, University of California, Irvine, California 92697
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15
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Yao T, Ndoja A. Regulation of gene expression by the ubiquitin-proteasome system. Semin Cell Dev Biol 2012; 23:523-9. [PMID: 22430757 DOI: 10.1016/j.semcdb.2012.02.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/06/2012] [Accepted: 02/10/2012] [Indexed: 12/26/2022]
Abstract
Transcription is the foremost regulatory point during the process of producing a functional protein. Not only specific genes need to be turned on and off according to growth and environmental conditions, the amounts and quality of transcripts produced are fine-tuned to offer optimal responses. As a result, numerous regulatory mechanisms converge to provide temporal and spatial specificity for this process. In the past decade, the ubiquitin-proteasome system (UPS), which is best known as a pathway for intracellular proteolysis, has emerged as another pivotal player in the control of gene expression. There is increasing evidence that the UPS has both proteolytic and non-proteolytic functions in multiple aspects of the transcription process, including initiation, elongation, mRNA processing as well as chromatin dynamics. In this review, we introduce the many interfaces between the UPS and transcription with focuses on the mechanistic understanding of UPS function in each process.
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Affiliation(s)
- Tingting Yao
- Colorado State University, Biochemistry and Molecular Biology, 1870 Campus Delivery, Fort Collins, CO 80523, USA.
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Babour A, Dargemont C, Stutz F. Ubiquitin and assembly of export competent mRNP. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:521-30. [PMID: 22240387 DOI: 10.1016/j.bbagrm.2011.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 12/20/2011] [Accepted: 12/22/2011] [Indexed: 11/24/2022]
Abstract
The production of mature and export competent mRNP (mRNA ribonucleoprotein) complexes depends on a series of highly coordinated processing reactions. RNA polymerase II (RNAPII) plays a central role in this process by mediating the sequential recruitment of mRNA maturation and export factors to transcribing genes, thereby establishing a strong functional link between transcription and export through nuclear pore complexes (NPC). Growing evidence indicates that post-translational modifications participate in the dynamic association of processing and export factors with mRNAs ensuring that the transitions and rearrangements undergone by the mRNP occur at the right time and place. This review mainly focuses on the role of ubiquitin conjugation in controlling mRNP assembly and quality control from transcription down to export through the NPC. It emphasizes the central role of ubiquitylation in organizing the chronology of events along this highly dynamic pathway. This article is part of a Special Issue entitled: Nuclear Transport and RNA Processing.
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Affiliation(s)
- Anna Babour
- Institut Jacques Monod, Université Paris Diderot, CNRS, Bâtiment Buffon, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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17
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Shcherbik N, Pestov DG. The ubiquitin ligase Rsp5 is required for ribosome stability in Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2011; 17:1422-8. [PMID: 21665996 PMCID: PMC3153967 DOI: 10.1261/rna.2615311] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Rsp5p is a conserved HECT-domain ubiquitin ligase with diverse roles in cellular physiology. Here we report a previously unknown role of Rsp5p in facilitating the stability of the cytoplasmic ribosome pool in budding yeast. Yeast strains carrying temperature-sensitive mutations in RSP5 showed a progressive decline in levels of 18S and 25S rRNAs and accumulation of rRNA decay fragments when cells grown in rich medium were shifted to restrictive temperature. This was accompanied by a decreased number of translating ribosomes and the appearance of ribosomal subunits with an abnormally low sedimentation rate in polysome analysis. Abrogating Rsp5p function affected stability of other tested noncoding RNA species (tRNA and snoRNA), but to a lower extent than that of rRNA, and also inhibited processing of rRNA and tRNA precursors, in agreement with previous studies. The breakdown of cellular ribosomes was not affected by deletion of key genes involved in autophagy, previously implicated in ribosome turnover upon starvation. Our results suggest that functional Rsp5p is required to maintain the integrity of cytoplasmic ribosomes under rich nutrient conditions.
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Affiliation(s)
- Natalia Shcherbik
- Department of Cell Biology, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084, USA
| | - Dimitri G. Pestov
- Department of Cell Biology, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084, USA
- Corresponding author.E-mail .
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18
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Kerr SC, Azzouz N, Fuchs SM, Collart MA, Strahl BD, Corbett AH, Laribee RN. The Ccr4-Not complex interacts with the mRNA export machinery. PLoS One 2011; 6:e18302. [PMID: 21464899 PMCID: PMC3065485 DOI: 10.1371/journal.pone.0018302] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 03/02/2011] [Indexed: 11/19/2022] Open
Abstract
Background The Ccr4-Not complex is a key eukaryotic regulator of gene transcription and cytoplasmic mRNA degradation. Whether this complex also affects aspects of post-transcriptional gene regulation, such as mRNA export, remains largely unexplored. Human Caf1 (hCaf1), a Ccr4-Not complex member, interacts with and regulates the arginine methyltransferase PRMT1, whose targets include RNA binding proteins involved in mRNA export. However, the functional significance of this regulation is poorly understood. Methodology/Principal Findings Here we demonstrate using co-immunoprecipitation approaches that Ccr4-Not subunits interact with Hmt1, the budding yeast ortholog of PRMT1. Furthermore, using genetic and biochemical approaches, we demonstrate that Ccr4-Not physically and functionally interacts with the heterogenous nuclear ribonucleoproteins (hnRNPs) Nab2 and Hrp1, and that the physical association depends on Hmt1 methyltransferase activity. Using mass spectrometry, co-immunoprecipitation and genetic approaches, we also uncover physical and functional interactions between Ccr4-Not subunits and components of the nuclear pore complex (NPC) and we provide evidence that these interactions impact mRNA export. Conclusions/Significance Taken together, our findings suggest that Ccr4-Not has previously unrealized functional connections to the mRNA processing/export pathway that are likely important for its role in gene expression. These results shed further insight into the biological functions of Ccr4-Not and suggest that this complex is involved in all aspects of mRNA biogenesis, from the regulation of transcription to mRNA export and turnover.
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Affiliation(s)
- Shana C. Kerr
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Department of Biochemistry, Cell, and Developmental Biology Graduate Program, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Nowel Azzouz
- Department of Microbiology and Molecular Medicine, University of Geneva Medical School, Geneva, Switzerland
| | - Stephen M. Fuchs
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Martine A. Collart
- Department of Microbiology and Molecular Medicine, University of Geneva Medical School, Geneva, Switzerland
| | - Brian D. Strahl
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Anita H. Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine and Center for Cancer Research, University of Tennessee Health Sciences Center, Memphis, Tennessee, United States of America
- * E-mail:
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19
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Yatherajam G, Huang W, Flint SJ. Export of adenoviral late mRNA from the nucleus requires the Nxf1/Tap export receptor. J Virol 2011; 85:1429-38. [PMID: 21123381 PMCID: PMC3028892 DOI: 10.1128/jvi.02108-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 11/22/2010] [Indexed: 01/04/2023] Open
Abstract
One important function of the human adenovirus E1B 55-kDa protein is induction of selective nuclear export of viral late mRNAs. This protein interacts with the viral E4 Orf6 and four cellular proteins to form an infected-cell-specific E3 ubiquitin ligase. The assembly of this enzyme is required for efficient viral late mRNA export, but neither the relevant substrates nor the cellular pathway that exports viral late mRNAs has been identified. We therefore examined the effects on viral late gene expression of inhibition of the synthesis or activity of the mRNA export receptor Nxf1, which was observed to colocalize with the E1B 55-kDa protein in infected cells. When production of Nxf1 was impaired by using RNA interference, the efficiency of viral late mRNA export was reduced to a corresponding degree. Furthermore, synthesis of a dominant-negative derivative of Nxf1 during the late phase of infection interfered with production of a late structural protein. These observations indicate that the Nxf1 pathway is responsible for export of viral late mRNAs. As the infected-cell-specific E3 ubiquitin ligase targets its known substrates for proteasomal degradation, we compared the concentrations of several components of this pathway (Nxf1, Thox1, and Thoc4) in infected cells that did or did not contain this enzyme. Although the concentration of a well-established substrate, Mre11, decreased significantly in cells infected by adenovirus type 5 (Ad5), but not in those infected by the E1B 55-kDa protein-null mutant Hr6, no E1B 55-kDa protein-dependent degradation of the Nxf1 pathway proteins was observed.
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Affiliation(s)
- Gayatri Yatherajam
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08854
| | - Wenying Huang
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08854
| | - S. J. Flint
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08854
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20
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Ossareh-Nazari B, Cohen M, Dargemont C. The Rsp5 ubiquitin ligase and the AAA-ATPase Cdc48 control the ubiquitin-mediated degradation of the COPII component Sec23. Exp Cell Res 2010; 316:3351-7. [PMID: 20846524 DOI: 10.1016/j.yexcr.2010.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 09/03/2010] [Accepted: 09/04/2010] [Indexed: 01/01/2023]
Abstract
Ubp3/Bre5 complex is a substrate-specific deubiquitylating enzyme which mediates deubiquitylation of Sec23, a component of the COPII complex involved in the transport between endoplasmic reticulum and Golgi apparatus. Here we show that ubiquitylation of Sec23 is controlled by the Rsp5 ubiquitin ligase both in vivo and in vitro. We have recently identified Cdc48, a chaperone-like that plays a key role in the proteasomal escort pathway, as a partner of the Ubp3/Bre5 complex. We now found that cdc48 thermosensitive mutant cells not only accumulate ubiquitylated form of Sec23 but also display a stabilization of this protein at the restrictive temperature. This indicates that Cdc48 controls the proteasome-mediated degradation of Sec23. Our data favor the idea that Cdc48 plays a key role in deciphering fates of ubiquitylated Sec23 to degradation or deubiquitylation/stabilization via its cofactors.
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21
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Iglesias N, Tutucci E, Gwizdek C, Vinciguerra P, Von Dach E, Corbett AH, Dargemont C, Stutz F. Ubiquitin-mediated mRNP dynamics and surveillance prior to budding yeast mRNA export. Genes Dev 2010; 24:1927-38. [PMID: 20810649 DOI: 10.1101/gad.583310] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The evolutionarily conserved mRNA export receptor Mex67/NXF1 associates with mRNAs through its adaptor, Yra1/REF, allowing mRNA ribonucleoprotein (mRNP) exit through nuclear pores. However, alternate adaptors should exist, since Yra1 is dispensable for mRNA export in Drosophila and Caenorhabditis elegans. Here we report that Mex67 interacts directly with Nab2, an essential shuttling mRNA-binding protein required for export. We further show that Yra1 enhances the interaction between Nab2 and Mex67, and becomes dispensable in cells overexpressing Nab2 or Mex67. These observations appoint Nab2 as a potential adaptor for Mex67, and define Yra1/REF as a cofactor stabilizing the adaptor-receptor interaction. Importantly, Yra1 ubiquitination by the E3 ligase Tom1 promotes its dissociation from mRNP before export. Finally, loss of perinuclear Mlp proteins suppresses the growth defects of Tom1 and Yra1 ubiquitination mutants, suggesting that Tom1-mediated dissociation of Yra1 from Nab2-bound mRNAs is part of a surveillance mechanism at the pore, ensuring export of mature mRNPs only.
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Affiliation(s)
- Nahid Iglesias
- Department of Cell Biology, Sciences III, 1211 Geneva 4, Switzerland.
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22
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Hiraishi H, Shimada T, Ohtsu I, Sato TA, Takagi H. The yeast ubiquitin ligase Rsp5 downregulates the alpha subunit of nascent polypeptide-associated complex Egd2 under stress conditions. FEBS J 2009; 276:5287-97. [DOI: 10.1111/j.1742-4658.2009.07226.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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23
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Shukla A, Durairaj G, Schneider J, Duan Z, Shadle T, Bhaumik SR. Stimulation of mRNA Export by an F-box Protein, Mdm30p, in Vivo. J Mol Biol 2009; 389:238-47. [DOI: 10.1016/j.jmb.2009.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 04/08/2009] [Accepted: 04/09/2009] [Indexed: 10/20/2022]
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24
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Hobeika M, Brockmann C, Gruessing F, Neuhaus D, Divita G, Stewart M, Dargemont C. Structural requirements for the ubiquitin-associated domain of the mRNA export factor Mex67 to bind its specific targets, the transcription elongation THO complex component Hpr1 and nucleoporin FXFG repeats. J Biol Chem 2009; 284:17575-83. [PMID: 19401465 DOI: 10.1074/jbc.m109.004374] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The ubiquitin-associated (UBA) domain of the principal Saccharomyces cerevisiae mRNA nuclear export factor, Mex67, can bind both nuclear pore protein (nucleoporin) FG repeats and Hpr1, a component of the TREX.THO complex that functions to link transcription and export. Using fluorescence resonance energy transfer-based assays, we show here that Hpr1 and the FG repeats interact with overlapping binding sites on the Mex67 UBA domain. We present the solution structure of the Mex67 UBA domain (UBA-Mex67) complexed with a FXFG nucleoporin peptide and define residues engaged in the interaction and those involved in the FXFG-induced conformational change. We show by NMR titration that the binding of Hpr1 produces analogous changes in chemical shifts in similar regions of the UBA domain. Together the data presented here indicate that both Hpr1 and FXFG nucleoporins may bind in a similar way to the UBA-Mex67 domain. However, whereas binding of Hpr1 allows UBA-Mex67 to interact with tetra-ubiquitin, the complex between UBA-Mex67 and FXFG is unable to bind mono- or tetra-ubiquitin, suggesting that both substrate binding and also the nature of the substrate may influence the affinity of the UBA-Mex67 domain for ubiquitin.
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Affiliation(s)
- Maria Hobeika
- Institut Jacques Monod, Université Paris VII, CNRS, 2 Place Jussieu, Tour 43, 75251 Paris Cedex 05, France
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25
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French ME, Kretzmann BR, Hicke L. Regulation of the RSP5 ubiquitin ligase by an intrinsic ubiquitin-binding site. J Biol Chem 2009; 284:12071-9. [PMID: 19252184 DOI: 10.1074/jbc.m901106200] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rsp5 is a homologous to E6AP C terminus (HECT) ubiquitin ligase (E3) that controls many different cellular processes in budding yeast. Although Rsp5 targets a number of different substrates for ubiquitination, the mechanisms that regulate Rsp5 activity remain poorly understood. Here we demonstrate that Rsp5 carries a noncovalent ubiquitin-binding site in its catalytic HECT domain. The N-terminal lobe of the HECT domain mediates binding to ubiquitin, and point mutations that disrupt interactions with ubiquitin alter the ability of the Rsp5 HECT domain to assemble polyubiquitin chains in vitro. Point mutations that disrupt ubiquitin binding also result in temperature-sensitive growth defects in yeast, indicating that the Rsp5 ubiquitin-binding site is important for Rsp5 function in vivo. The Nedd4 HECT domain N-lobe also contains ubiquitin-binding activity, suggesting that interactions between the N-lobe and ubiquitin are conserved within the Nedd4 family of ubiquitin ligases. We propose that a subset of HECT E3s are regulated by a conserved ubiquitin-binding site that functions to restrict the length of polyubiquitin chains synthesized by the HECT domain.
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Affiliation(s)
- Michael E French
- Department of Biochemistry, Molecular Biology & Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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26
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Haitani Y, Nakata M, Sasaki T, Uchida A, Takagi H. Engineering of the yeast ubiquitin ligase Rsp5: isolation of a new variant that induces constitutive inactivation of the general amino acid permease Gap1. FEMS Yeast Res 2009; 9:73-86. [DOI: 10.1111/j.1567-1364.2008.00460.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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27
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Versatile role of the yeast ubiquitin ligase Rsp5p in intracellular trafficking. Biochem Soc Trans 2008; 36:791-6. [PMID: 18793138 DOI: 10.1042/bst0360791] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ubiquitin ligase (E3) Rsp5p is the only member of the Nedd (neural-precursor-cell-expressed, developmentally down-regulated) 4 family of E3s present in yeast. Rsp5p has several proteasome-independent functions in membrane protein trafficking, including a role in the ubiquitination of most plasma membrane proteins, leading to their endocytosis. Rsp5p is also required for the ubiquitination of endosomal proteins, leading to their sorting to the internal vesicles of MVBs (multivesicular bodies). Rsp5p catalyses the attachment of non-conventional ubiquitin chains, linked through ubiquitin Lys-63, to some endocytic and MVB cargoes. This modification appears to be required for efficient sorting, possibly because these chains have a greater affinity for the ubiquitin-binding domains present within endocytic or MVB sorting complexes. The mechanisms involved in the recognition of plasma membrane and MVB substrates by Rsp5p remain unclear. A subset of Rsp5/Nedd4 substrates have a 'PY motif' and are recognized directly by the WW (Trp-Trp) domains of Rsp5p. Most Rsp5p substrates do not carry PY motifs, but some may depend on PY-containing proteins for their ubiquitination by Rsp5p, consistent with the latter's acting as specificity factors or adaptors. As in other ubiquitin-conjugating systems, these adaptors are also Rsp5p substrates and undergo ubiquitin-dependent trafficking. In the present review, we discuss recent examples illustrating the role of Rsp5p in membrane protein trafficking and providing new insights into the regulation of this E3 by adaptor proteins.
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28
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Stawiecka-Mirota M, Kamińska J, Urban-Grimal D, Haines DS, Żołądek T. Nedd4, a human ubiquitin ligase, affects actin cytoskeleton in yeast cells. Exp Cell Res 2008; 314:3318-25. [DOI: 10.1016/j.yexcr.2008.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 08/25/2008] [Accepted: 08/25/2008] [Indexed: 11/29/2022]
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29
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Kaliszewski P, Szkopińska A, Ferreira T, Swiezewska E, Berges T, Zoładek T. Rsp5p ubiquitin ligase and the transcriptional activators Spt23p and Mga2p are involved in co-regulation of biosynthesis of end products of the mevalonate pathway and triacylglycerol in yeast Saccharomyces cerevisiae. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1781:627-34. [PMID: 18771750 DOI: 10.1016/j.bbalip.2008.07.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 07/11/2008] [Accepted: 07/23/2008] [Indexed: 01/10/2023]
Abstract
Rsp5p, a yeast S. cerevisiae ubiquitin ligase, is essential for regulation of unsaturated fatty acid synthesis via activation of the transcriptional activators Spt23p and Mga2p. Here we show that the conditional mutant rsp5-19 produces decreased levels of the end products of mevalonate pathway, such as ergosterol, ubiquinone and of dolichols, especially those with 19-24 isoprene units. The mechanism of Rsp5p involvement in the control of these lipid synthesis pathways was addressed by overproduction of Rsp5p-independent Spt23p or Mga2p. Expression of constitutively active forms of these transactivators resulted in excess production of ergosterol, but did not restore a wild-type level of dolichols. Moreover, synthesis of long chain dolichols was decreased in the wild-type and a rsp5-19 background. Finally, overproduction of active Spt23p or Mga2p was accompanied by the appearance of large lipid particles in the wild-type and rsp5-19 strains as observed by Nile Red staining, due to accumulation of unsaturated triacylglycerol. Thus, we conclude that Rsp5p, Spt23p and Mga2p may participate in the control of the homeostasis of lipids and lipid particles.
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Affiliation(s)
- Paweł Kaliszewski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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30
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Iglesias N, Stutz F. Regulation of mRNP dynamics along the export pathway. FEBS Lett 2008; 582:1987-96. [PMID: 18394429 DOI: 10.1016/j.febslet.2008.03.038] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 03/25/2008] [Accepted: 03/26/2008] [Indexed: 02/02/2023]
Abstract
The transcription of mRNA is tightly coupled to the concomitant recruitment of mRNA processing and export factors, resulting in the formation of mature and export competent mRNP complexes. This interconnection in gene expression implies extensive spatio-temporal control of mRNP dynamics to prevent mRNA export factors bound to pre-mRNA from functioning at the incorrect time and exporting nascent or incompletely processed pre-mRNAs. Recent discoveries provide molecular understanding of how a broad range of post-translational modifications together with RNA-dependent ATPases coordinate proteins acting at different steps and regulate mRNP assembly and export.
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Affiliation(s)
- Nahid Iglesias
- Department of Cell Biology, University of Geneva, 30 Quai E. Ansermet, 1211 Geneva 4, Switzerland
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31
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Haitani Y, Takagi H. Rsp5 is required for the nuclear export of mRNA of HSF1 and MSN2/4 under stress conditions in Saccharomyces cerevisiae. Genes Cells 2008; 13:105-16. [PMID: 18233954 DOI: 10.1111/j.1365-2443.2007.01154.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Rsp5 is an essential and multi-functional E3 ubiquitin ligase in Saccharomyces cerevisiae. We previously isolated the Ala401Glu rsp5 mutant that is hypersensitive to various stresses. In rsp5(A401E) cells, the transcription of the stress protein genes was defective. To understand the mechanism by which Rsp5 regulates the expression of stress proteins, we analyzed the expression and localization of two major transcription factors, Hsf1 and Msn2/4, required for stress protein gene expression in S. cerevisiae. The mRNA levels of HSF1 and MSN2/4 in rsp5(A401E) cells were slightly lower than those of wild-type cells. An interesting finding is that the protein levels of HSF1 and Msn2/4 were remarkably defective in rsp5(A401E) cells after exposure to temperature up-shift and ethanol, although these proteins are mainly localized in the nucleus under these stress conditions. We also showed that the mRNAs of HSF1 and MSN2/4 were accumulated in the nucleus of rsp5(A401E) cells after exposure to temperature up-shift and ethanol, and even under non-stress conditions, suggesting that Rsp5 is required for the nuclear export of these mRNAs. These results indicate that, in response to environmental stresses, Rsp5 primarily regulates the expression of Hsf1 and Msn2/4 at the post-transcriptional level and is involved in the repair system of stress-induced abnormal proteins.
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Affiliation(s)
- Yutaka Haitani
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
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32
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Demae M, Murata Y, Hisano M, Haitani Y, Shima J, Takagi H. Overexpression of two transcriptional factors, Kin28 and Pog1, suppresses the stress sensitivity caused by thersp5mutation inSaccharomyces cerevisiae. FEMS Microbiol Lett 2007; 277:70-8. [DOI: 10.1111/j.1574-6968.2007.00947.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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33
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Mannen T, Andoh T, Tani T. Dss1 associating with the proteasome functions in selective nuclear mRNA export in yeast. Biochem Biophys Res Commun 2007; 365:664-71. [PMID: 18023413 DOI: 10.1016/j.bbrc.2007.11.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 11/06/2007] [Indexed: 10/22/2022]
Abstract
Dss1p is an evolutionarily conserved small protein that interacts with BRCA2, a tumor suppressor protein, in humans. The Schizosaccharomyces pombe strain lacking the dss1(+) gene (Deltadss1) shows a temperature-sensitive growth defect and accumulation of bulk poly(A)(+) RNA in the nucleus at a nonpermissive temperature. In situ hybridization using probes for several specific mRNAs, however, revealed that the analyzed mRNAs were exported normally to the cytoplasm in Deltadss1, suggesting that Dss1p is required for export of some subsets of mRNAs. We identified the pad1(+) gene, which encodes a component of the 26S proteasome, as a suppressor for the ts(-) phenotype of Deltadss1. Unexpectedly, overexpression of Pad1p could suppress neither the defect in nuclear mRNA export nor a defect in proteasome function. In addition, loss of proteasome functions does not cause defective nuclear mRNA export. Dss1p seems to be a multifunctional protein involved in nuclear export of specific sets of mRNAs and the ubiquitin-proteasome pathway in fission yeast.
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Affiliation(s)
- Taro Mannen
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
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34
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Bhattacharya S, Zoladek T, Haines DS. WW domains 2 and 3 of Rsp5p play overlapping roles in binding to the LPKY motif of Spt23p and Mga2p. Int J Biochem Cell Biol 2007; 40:147-57. [PMID: 17719829 PMCID: PMC2129131 DOI: 10.1016/j.biocel.2007.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 07/05/2007] [Accepted: 07/16/2007] [Indexed: 12/23/2022]
Abstract
Rsp5p of Saccharomyces cerevisiae is a member of the C2-WW-HECT family of ubiquitin ligases and it interacts with targets via its WW domains. Spt23p and Mga2p are Rsp5p substrates and Rsp5p activates the OLE1 inducing functions of these membrane-localized transcription factors by ubiquitination. Although it is known that Rsp5p binds Mga2p and Spt23p via an imperfect WW domain-binding site (LPKY) that is located within the carboxy-terminal domain of the proteins, it remains unclear which WW domains mediate binding. We show that Rsp5p mutants harboring mutations in single WW domains are Spt23p/Mga2p binding and ubiquitination proficient. This is also the case for WW domains 1/2 and WW domains 1/3 mutants. However, disrupting WW domains 2 and 3 abrogates a physical and functional interaction with substrates in vitro and in cells. We also show that abrogation of WW domains 2 and 3 eliminates the activity of an Rsp5p dominant-negative mutant and an rsp5 WW domain 2/3 mutant is unable to rescue the proliferative defects of rsp5 Delta cells. Interestingly, while rsp5 Delta cells are able to grow on oleic acid containing YPD media, they as well as those transformed with the WW domain 2/3 mutant are unable to proliferate on oleic acid containing synthetic drop-out media. We conclude from these studies that WW domains 2 and 3 of Rsp5p play overlapping roles in binding to the LPKY site on Spt23p and Mga2p. Also, we propose that WW domains 2 and 3 perform yet to be defined essential function(s) outside of the OLE1 pathway when cells are grown in nutrient restrictive media.
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Affiliation(s)
- Sabyasachi Bhattacharya
- Fels Institute for Cancer Research and Molecular Biology and the Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Teresa Zoladek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Department of Genetics, Warsaw, Poland
| | - Dale S. Haines
- Fels Institute for Cancer Research and Molecular Biology and the Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
- *Corresponding author: Dale S. Haines, Ph.D. (Phone: 215-707-5765, )
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Hobeika M, Brockmann C, Iglesias N, Gwizdek C, Neuhaus D, Stutz F, Stewart M, Divita G, Dargemont C. Coordination of Hpr1 and ubiquitin binding by the UBA domain of the mRNA export factor Mex67. Mol Biol Cell 2007; 18:2561-8. [PMID: 17475778 PMCID: PMC1924821 DOI: 10.1091/mbc.e07-02-0153] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The ubiquitin-associated (UBA) domain of the mRNA nuclear export receptor Mex67 helps in coordinating transcription elongation and nuclear export by interacting both with ubiquitin conjugates and specific targets, such as Hpr1, a component of the THO complex. Here, we analyzed substrate specificity and ubiquitin selectivity of the Mex67 UBA domain. UBA-Mex67 is formed by three helices arranged in a classical UBA fold plus a fourth helix, H4. Deletion or mutation of helix H4 strengthens the interaction between UBA-Mex67 and ubiquitin, but it decreases its affinity for Hpr1. Interaction with Hpr1 is required for Mex67 UBA domain to bind polyubiquitin, possibly by inducing an H4-dependent conformational change. In vivo, deletion of helix H4 reduces cotranscriptional recruitment of Mex67 on activated genes, and it also shows an mRNA export defect. Based on these results, we propose that H4 functions as a molecular switch that coordinates the interaction of Mex67 with ubiquitin bound to specific substrates, defines the selectivity of the Mex67 UBA domain for polyubiquitin, and prevents its binding to nonspecific substrates.
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Affiliation(s)
- Maria Hobeika
- Institut Jacques Monod, Universités Paris VI and VII, Centre National de la Recherche Scientifique, 75251 Paris Cedex 05, France
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36
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Gwizdek C, Iglesias N, Rodriguez MS, Ossareh-Nazari B, Hobeika M, Divita G, Stutz F, Dargemont C. Ubiquitin-associated domain of Mex67 synchronizes recruitment of the mRNA export machinery with transcription. Proc Natl Acad Sci U S A 2006; 103:16376-81. [PMID: 17056718 PMCID: PMC1637590 DOI: 10.1073/pnas.0607941103] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mRNA nuclear export receptor Mex67/Mtr2 is recruited to mRNAs through RNA-binding adaptors, including components of the THO/TREX complex that couple transcription to mRNA export. Here we show that the ubiquitin-associated (UBA) domain of Mex67 is not only required for proper nuclear export of mRNA but also contributes to recruitment of Mex67 to transcribing genes. Our results reveal that the UBA domain of Mex67 directly interacts with polyubiquitin chains and with Hpr1, a component of the THO/TREX complex, which is regulated by ubiquitylation in a transcription-dependent manner. This interaction transiently protects Hpr1 from ubiquitin/proteasome-mediated degradation and thereby coordinates recruitment of the mRNA export machinery with transcription and early messenger ribonucleoproteins assembly.
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Affiliation(s)
- Carole Gwizdek
- *Institut Jacques Monod, Unité Mixte de Recherche 7592, Centre National de la Recherche Scientifique, Universités Paris VI and VII, 2 Place Jussieu, Tour 43, 75251 Paris Cedex 05, France
| | - Nahid Iglesias
- Department of Cell Biology, Sciences III, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland; and
| | - Manuel S. Rodriguez
- *Institut Jacques Monod, Unité Mixte de Recherche 7592, Centre National de la Recherche Scientifique, Universités Paris VI and VII, 2 Place Jussieu, Tour 43, 75251 Paris Cedex 05, France
| | - Batool Ossareh-Nazari
- *Institut Jacques Monod, Unité Mixte de Recherche 7592, Centre National de la Recherche Scientifique, Universités Paris VI and VII, 2 Place Jussieu, Tour 43, 75251 Paris Cedex 05, France
| | - Maria Hobeika
- *Institut Jacques Monod, Unité Mixte de Recherche 7592, Centre National de la Recherche Scientifique, Universités Paris VI and VII, 2 Place Jussieu, Tour 43, 75251 Paris Cedex 05, France
| | - Gilles Divita
- Centre de Recherches de Biochimie Macromoléculaire, Centre National de la Recherche Scientifique Formation de Recherche en Evolution-2593, Molecular Biophysics and Therapeutics, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Françoise Stutz
- Department of Cell Biology, Sciences III, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland; and
- To whom correspondence may be addressed. E-mail:
or
| | - Catherine Dargemont
- *Institut Jacques Monod, Unité Mixte de Recherche 7592, Centre National de la Recherche Scientifique, Universités Paris VI and VII, 2 Place Jussieu, Tour 43, 75251 Paris Cedex 05, France
- To whom correspondence may be addressed. E-mail:
or
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37
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Froissard M, Belgareh-Touzé N, Buisson N, Desimone M, Frommer WB, Haguenauer-Tsapis R. Heterologous expression of a plant uracil transporter in yeast: Improvement of plasma membrane targeting in mutants of the Rsp5p ubiquitin protein ligase. Biotechnol J 2006; 1:308-20. [PMID: 16897711 DOI: 10.1002/biot.200500034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Plasma membrane proteins involved in transport processes play a crucial role in cell physiology. On account of these properties, these molecules are ideal targets for development of new therapeutic and agronomic agents. However, these proteins are of low abundance, which limits their study. Although yeast seems ideal for expressing heterologous transporters, plasma membrane proteins are often retained in intracellular compartments. We tried to find yeast mutants potentially able to improve functional expression of a whole set of heterologous transporters. We focused on Arabidopsis thaliana ureide transporter 1 (AtUPS1), previously cloned by functional complementation in yeast. Tagged versions of AtUPS1 remain mostly trapped in the endoplasmic reticulum and were able to reach slowly the plasma membrane. In contrast, untagged AtUPS1 is rapidly delivered to plasma membrane, where it remains in stable form. Tagged and untagged versions of AtUPS1 were expressed in cells deficient in the ubiquitin ligase Rsp5p, involved in various stages of the intracellular trafficking of membrane-bound proteins. rsp5 mutants displayed improved steady state amounts of untagged and tagged versions of AtUPS1. rsp5 cells are thus powerful tools to solve the many problems inherent to heterologous expression of membrane proteins in yeast, including ER retention.
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Affiliation(s)
- Marine Froissard
- Institut Jacques Monod-CNRS, Université Paris VI and Paris VII, Paris, France
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38
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Kikkert M, Hassink G, Wiertz E. The role of the ubiquitination machinery in dislocation and degradation of endoplasmic reticulum proteins. Curr Top Microbiol Immunol 2006; 300:57-93. [PMID: 16573237 DOI: 10.1007/3-540-28007-3_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ubiquitination is essential for the dislocation and degradation of proteins from the endoplasmic reticulum (ER). How exactly this is regulated is unknown at present. This review provides an overview of ubiquitin-conjugating enzymes (E2s) and ubiquitin ligases (E3s) with a role in the degradation of ER proteins. Their structure and functions are described, as well as their mutual interactions. Substrate specificity and functional redundancy of E3 ligases are discussed, and other components of the ER degradation machinery that may associate with the ubiquitination system are reviewed.
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Affiliation(s)
- M Kikkert
- Department of Medical Microbiology, Leiden University Medical Center (LUMC), Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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39
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Kwapisz M, Cholbinski P, Hopper AK, Rousset JP, Zoladek T. Rsp5 ubiquitin ligase modulates translation accuracy in yeast Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2005; 11:1710-8. [PMID: 16177134 PMCID: PMC1370857 DOI: 10.1261/rna.2131605] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Rsp5p is an essential yeast ubiquitin protein ligase that ubiquitinates multiple proteins involved in various processes. Recent studies indicate that ubiquitination also affects translation. Here, we show that the strain with the rsp5-13 mutation exhibits altered sensitivity to antibiotics and a slower rate of translation. Using a sensitive dual-gene reporter system, we demonstrate that stop codon readthrough efficiency is decreased in the rsp5-13 mutant, while both +1 and -1 frameshifting were unaffected. The effect of the rsp5-13 mutation on readthrough could be reversed by increased expression of ubiquitin and partially suppressed by overproduction of the elongation factor eEF1A. As assessed by fluorescence in situ hybridization, the rsp5-13 mutant cells accumulate tRNA nuclear pools, perhaps depleting tRNA from the cytoplasm. Nuclear accumulation of tRNA is observed only when rsp5-13 cells are grown in media with high amino acid content. This defect, also reversed by overproduction of the elongation factor eEF1A, may be the primary reason for altered translational decoding accuracy.
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Affiliation(s)
- Marta Kwapisz
- Department of Genetics, Institute of Biochemistry and Biophysics, PAS, Warsaw, Poland
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40
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Abstract
mRNAs are transported from the nucleus to the cytoplasm by a machinery conserved from yeast to humans. Previous studies showed that mRNA export factors are loaded on nascent mRNAs during elongation, coupling transcription to export. More recently identified mRNA export factors connect transcription initiation to the export machinery associated with nuclear pores, and potentially tether active genes to the nuclear periphery. Furthermore, a newly identified link between the nuclear exosome and the transcription, 3'-end formation and export machineries suggests that early messenger ribonucleoprotein complex (mRNP) assembly is co-transcriptionally monitored. Moreover, inefficient mRNP assembly impairs transcription elongation, indicating tight interdependence of these processes. Finally, nuclear retention of unspliced mRNAs by the perinuclear Mlp proteins reveals a novel mechanism of mRNP surveillance prior to export.
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Affiliation(s)
- Patrizia Vinciguerra
- Department of Cell Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, 1211 Geneva 4, Switzerland
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41
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Gwizdek C, Hobeika M, Kus B, Ossareh-Nazari B, Dargemont C, Rodriguez MS. The mRNA nuclear export factor Hpr1 is regulated by Rsp5-mediated ubiquitylation. J Biol Chem 2005; 280:13401-5. [PMID: 15713680 DOI: 10.1074/jbc.c500040200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ubiquitin conjugation and in particular two distinct HECT ubiquitin ligases, Rsp5p and Tom1p, have been shown to participate in the regulation of mRNA export in Saccharomyces cerevisiae. The identification of the ubiquitin ligase substrates represents a major challenge in understanding how this modification may modulate mRNA export. Here, we identified Hpr1p, a member of the THO/TREX (transcription/export) complex that couples mRNA transcription to nuclear export as a target of the ubiquitin-proteasome pathway. Hpr1p degradation is enhanced at high temperature and appears linked to on-going RNA-polymeraseII-mediated transcription. Interestingly, the stability of the other THO complex components is not affected under these conditions indicating that Hpr1p turnover could control the formation of the THO/TREX complex and consequently mRNA export. Using in vivo and in vitro approaches we demonstrate that Rsp5p is responsible for the ubiquitylation of Hpr1p that also involves the ubiquitin-conjugating enzyme Ubc4p. Thus, Hpr1p represents the first nuclear export factor regulated by ubiquitylation, strongly suggesting that this post-translational modification participates in the coordination of transcription and mRNA export processes.
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Affiliation(s)
- Carole Gwizdek
- Institut Jacques Monod, Unité Mixte de Recherche 7592, CNRS, Universités Paris VI and VII, 75251 Paris Cedex 05, France
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42
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Morvan J, Froissard M, Haguenauer-Tsapis R, Urban-Grimal D. The ubiquitin ligase Rsp5p is required for modification and sorting of membrane proteins into multivesicular bodies. Traffic 2004; 5:383-92. [PMID: 15086787 DOI: 10.1111/j.1398-9219.2004.00183.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Precursor forms of vacuolar proteins with transmembrane domains, such as the carboxypeptidase S Cps1p and the polyphosphatase Phm5p, are selectively sorted in endosomal compartments to vesicles that invaginate, budding into the lumen of the late endosomes, resulting in the formation of multivesicular bodies (MVBs). These proteins are then delivered to the vacuolar lumen following fusion of the MVBs with the vacuole. The sorting of Cps1p and Phm5p to these structures is mediated by ubiquitylation, and in doa4 mutant cells, which have reduced level of free ubiquitin, these proteins are missorted to the vacuolar membrane. A RING-finger ubiquitin ligase Tul1p has been shown to participate in the ubiquitylation of Cps1p and Phm5p. We show here that the HECT-ubiquitin ligase Rsp5p is also required for the ubiquitylation of these proteins, and therefore for their sorting to MVBs. Rsp5p is an essential ubiquitin ligase containing an N-terminal C2 domain followed by three WW domains, and a C-terminal catalytic HECT domain. In cells with low levels of Rsp5p (npi1 mutant cells), vacuolar hydrolases do not reach the vacuolar lumen and are instead missorted to the vacuolar membrane. The C2 domain and both the second and third WW domains of Rsp5p are important determinants for sorting to MVBs. Ubiquitylation of Cps1p was strongly reduced in the npi1 mutant strain and ubiquitylation was completely abolished in the npi1 tul1Delta double mutant. These data demonstrate that Rsp5p plays a novel and key role in intracellular trafficking, and extend the currently very short list of substrates ubiquitylated in vivo by several different ubiquitin ligases acting cooperatively.
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Affiliation(s)
- Joelle Morvan
- Institut Jacques Monod, CNRS-UMRC9922, Universités Paris 6 and Paris 7-Denis Diderot, 2 place Jussieu, 75251-Paris-cedex 05, France
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Shcherbik N, Kee Y, Lyon N, Huibregtse JM, Haines DS. A Single PXY Motif Located within the Carboxyl Terminus of Spt23p and Mga2p Mediates a Physical and Functional Interaction with Ubiquitin Ligase Rsp5p. J Biol Chem 2004; 279:53892-8. [PMID: 15466864 DOI: 10.1074/jbc.m410325200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteasome-dependent processing of the endoplasmic reticulum localized transcription factor Spt23p of Saccharomyces cerevisiae generates its transcriptionally competent form and requires the WW domain containing Rsp5p ubiquitin ligase. Although previous studies documented an Rsp5p-Spt23p association in cells, very little is known about the nature of this interaction. We report here the identification of an imperfect type I WW domain-binding site (LPKY) within the carboxyl-terminal region of Spt23p that is required for Rsp5p binding in vitro and in vivo. Deletion of this motif abrogates Rsp5p-induced ubiquitination of Spt23p in vitro and reduces ubiquitination of the Spt23p precursor in yeast. In addition, the Spt23pDeltaLPKY mutant is inefficiently processed and is defective at up-regulating target gene (OLE1) expression in cells. Deletion of the corresponding LPKY site within Mga2p, an Spt23p homologue, also abrogates Rsp5p binding and Rsp5p-dependent ubiquitination in vitro as well as Rsp5p binding and Mga2p polyubiquitination in cells. However, the Mga2pDeltaLPKY mutant undergoes efficient proteasome-dependent processing. These experiments indicate that the LPKY motif of Spt23p is required for Rsp5p binding, Rsp5-induced ubiquitination, proteasome-dependent processing, and its OLE1 inducing function. They also suggest that the LPKY motif of Mga2p is required for Rsp5p binding and ubiquitination, and Rsp5p regulates Mga2p function by a mechanism that is independent of providing the partial degradation signal.
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Affiliation(s)
- Natalia Shcherbik
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, 3307 N. Broad St., Philadelphia, PA 19140, USA
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Krsmanović T, Kölling R. The HECT E3 ubiquitin ligase Rsp5 is important for ubiquitin homeostasis in yeast. FEBS Lett 2004; 577:215-9. [PMID: 15527788 DOI: 10.1016/j.febslet.2004.10.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2004] [Revised: 10/01/2004] [Accepted: 10/03/2004] [Indexed: 10/26/2022]
Abstract
The HECT E3 ubiquitin ligase Rsp5, a yeast member of the Nedd4 family, has been implicated in many different aspects of cell physiology. Here, we present evidence that Rsp5 function is important for ubiquitin homeostasis. Several observations suggest that ubiquitin is limiting in the rsp5-1 mutant. Reduced synthesis of ubiquitin appears to contribute to ubiquitin depletion. A transient inhibition of general protein synthesis is observed in a wildtype strain upon heat-shock. While the wildtype cells quickly recover from this transient arrest, the rsp5-1 cells remain arrested. This suggests that Rsp5 is important for recovery from heat-induced protein synthesis arrest. Our results suggest that rsp5 phenotypes should be interpreted with caution, since some of the phenotypes could be simply the result of ubiquitin limitation.
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Affiliation(s)
- Tamara Krsmanović
- Institut für Mikrobiologie, Geb. 26.12.01, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
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45
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Hegde AN. Ubiquitin-proteasome-mediated local protein degradation and synaptic plasticity. Prog Neurobiol 2004; 73:311-57. [PMID: 15312912 DOI: 10.1016/j.pneurobio.2004.05.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2003] [Accepted: 05/28/2004] [Indexed: 02/07/2023]
Abstract
A proteolytic pathway in which attachment of a small protein, ubiquitin, marks the substrates for degradation by a multi-subunit complex called the proteasome has been shown to function in synaptic plasticity and in several other physiological processes of the nervous system. Attachment of ubiquitin to protein substrates occurs through a series of highly specific and regulated steps. Degradation by the proteasome is subject to multiple levels of regulation as well. How does the ubiquitin-proteasome pathway contribute to synaptic plasticity? Long-lasting, protein synthesis-dependent, changes in the synaptic strength occur through activation of molecular cascades in the nucleus in coordination with signaling events in specific synapses. Available evidence indicates that ubiquitin-proteasome-mediated degradation has a role in the molecular mechanisms underlying synaptic plasticity that operate in the nucleus as well as at the synapse. Since the ubiquitin-proteasome pathway has been shown to be versatile in having roles in addition to proteolysis in several other cellular processes relevant to synaptic plasticity, such as endocytosis and transcription, this pathway is highly suited for a localized role in the neuron. Because of its numerous roles, malfunctioning of this pathway leads to several diseases and disorders of the nervous system. In this review, I examine the ubiquitin-proteasome pathway in detail and describe the role of regulated proteolysis in long-term synaptic plasticity. Also, using synaptic tagging theory of synapse-specific plasticity, I provide a model on the possible roles and regulation of local protein degradation by the ubiquitin-proteasome pathway.
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Affiliation(s)
- Ashok N Hegde
- Department of Neurobiology and Anatomy, Medical Center Boulevard, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA.
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46
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Andoh T, Azad AK, Shigematsu A, Ohshima Y, Tani T. The fission yeast ptr1+ gene involved in nuclear mRNA export encodes a putative ubiquitin ligase. Biochem Biophys Res Commun 2004; 317:1138-43. [PMID: 15094387 DOI: 10.1016/j.bbrc.2004.03.171] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Indexed: 10/26/2022]
Abstract
Fission yeast ptr1-1 is one of the mRNA transport mutants that accumulate poly(A)+ RNA in the nuclei at the nonpermissive temperature. We found that the ptr1+ gene encodes a homolog of Saccharomyces cerevisiae Tom1p, a hect type ubiquitin ligase. In ptr1-1, a conserved amino acid in the hect domain of Ptr1p is mutated. The ptr1+ gene is essential for growth and its mutation did not affect nuclear protein export. A ptr1-1 rae1-167 double mutant showed a synthetic effect on a growth defect, indicating that Ptr1p functionally interacts with an essential mRNA export factor Rae1p. We also isolated a multi-copy suppressor for ptr1-1 and found that it is the mpd2+ gene isolated as a multi-copy suppressor of cdc7-PD1.
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Affiliation(s)
- Tomoko Andoh
- Department of Biological Science, Faculty of Science, Kumamoto University, Kurokami, Kumamoto 860-8555, Japan
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47
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Neumann S, Petfalski E, Brügger B, Großhans H, Wieland F, Tollervey D, Hurt E. Formation and nuclear export of tRNA, rRNA and mRNA is regulated by the ubiquitin ligase Rsp5p. EMBO Rep 2003; 4:1156-62. [PMID: 14608372 PMCID: PMC1326418 DOI: 10.1038/sj.embor.7400026] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Revised: 09/15/2003] [Accepted: 09/22/2003] [Indexed: 11/08/2022] Open
Abstract
The yeast ubiquitin-protein ligase Rsp5p regulates processes as diverse as polII transcription and endocytosis. Here, we identify Rsp5p in a screen for tRNA export (tex) mutants. The tex23-1/rsp5-3 mutant, which is complemented by RSP5, not only shows a strong nuclear accumulation of tRNAs at the restrictive temperature, but also is severely impaired in the nuclear export of mRNAs and 60S pre-ribosomal subunits. In contrast, nuclear localization sequence (NLS)-mediated nuclear protein import is unaffected in this mutant. Strikingly, the nuclear RNA export defects seen in the rsp5-3 strain are accompanied by a dramatic inhibition of both rRNA and tRNA processing, a combination of phenotypes that has not been reported for any previously characterized mutation in yeast. These data implicate ubiquitination as a mechanism coordinating the major nuclear RNA biogenesis pathways.
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Affiliation(s)
- Silvia Neumann
- Biochemie-Zentrum Heidelberg (BZH),
Im Neuenheimer Feld 328, D-69120
Heidelberg, Germany
| | - Elisabeth Petfalski
- Wellcome Trust Centre for Cell Biology,
University of Edinburgh, Edinburgh EH9 3JR,
UK
| | - Britta Brügger
- Biochemie-Zentrum Heidelberg (BZH),
Im Neuenheimer Feld 328, D-69120
Heidelberg, Germany
| | - Helge Großhans
- Biochemie-Zentrum Heidelberg (BZH),
Im Neuenheimer Feld 328, D-69120
Heidelberg, Germany
| | - Felix Wieland
- Biochemie-Zentrum Heidelberg (BZH),
Im Neuenheimer Feld 328, D-69120
Heidelberg, Germany
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology,
University of Edinburgh, Edinburgh EH9 3JR,
UK
| | - Ed Hurt
- Biochemie-Zentrum Heidelberg (BZH),
Im Neuenheimer Feld 328, D-69120
Heidelberg, Germany
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