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Xiong Y, Wang L, Xu S, Fu B, Che Y, Zaky MY, Tian R, Yao R, Guo D, Sha Z, Lin F, Lin X, Wu H. Small molecule Z363 co-regulates TAF10 and MYC via the E3 ligase TRIP12 to suppress tumour growth. Clin Transl Med 2023; 13:e1153. [PMID: 36639831 PMCID: PMC9839843 DOI: 10.1002/ctm2.1153] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/17/2022] [Accepted: 08/12/2022] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND The MYC oncoprotein, also known as the master regulator of genes, is a transcription factor that regulates numerous physiological processes, including cell cycle control, apoptosis, protein synthesis and cell adhesion, among others. MYC is overexpressed in approximately 70% of human cancers. Given its pervasive role in cancer biology, MYC down-regulation has become an attractive cancer treatment strategy. METHODS The CRISPR/Cas9 method was used to produce KO cell models. Western blot was used to analyzed the expressions of MYC and TATA-binding proteinassociated factors 10 (TAF10) in cancer cells (MCF7, A549, HepG2 cells) Cell culture studies were performed to determine the mechanisms by which small molecules (Z363119456, Z363) affects MYC and TAF10 expressions and functions. Mouse studies were carried out to investigate the impact of Z363 regulation on tumor growth. RESULTS Z363 activate Thyroid hormone Receptor-interacting Protein 12 (TRIP12), which phosphorylates MYC at Thr58, resulting in MYC ubiquitination and degradation and thereby regulating MYC target genes. Importantly, TRIP12 also induces TAF10 degradation, which reduces MYC protein levels. TRIP12, an E3 ligase, controls MYC levels both directly and indirectly by inhibiting MYC or TAF10 activity. CONCLUSIONS In summary,these results demonstrate the anti-cancer properties of Z363, a small molecule that is co-regulated by TAF10 and MYC.
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Affiliation(s)
- Yan Xiong
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Lulu Wang
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Shiyao Xu
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Beibei Fu
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Yuchen Che
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Mohamed Y. Zaky
- Molecular Physiology DivisionZoology DepartmentFaculty of ScienceBeni‐Suef UniversityBeni‐SuefEgypt,Department of OncologyFaculty of MedicineLinköping UniversitySweden,Department of Biomedical and Clinical SciencesFaculty of MedicineLinköping UniversitySweden
| | - Rong Tian
- Department of Biomedical and Clinical SciencesFaculty of MedicineLinköping UniversitySweden
| | - Rui Yao
- Department of PathologyChongqing Hygeia HospitalChongqingChina
| | - Dong Guo
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Zhou Sha
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Feng Lin
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Xiaoyuan Lin
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
| | - Haibo Wu
- Department of Physiology, School of Life SciencesChongqing UniversityChongqingChina
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2
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Wang Z, Spoel SH. HECT ubiquitin ligases as accessory proteins of the plant proteasome. Essays Biochem 2022; 66:135-145. [PMID: 35635104 PMCID: PMC9400063 DOI: 10.1042/ebc20210064] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/21/2022] [Accepted: 04/29/2022] [Indexed: 12/31/2022]
Abstract
The proteasome plays vital roles in eukaryotic cells by orchestrating the regulated degradation of large repertoires of substrates involved in numerous biological processes. Proteasome dysfunction is associated with a wide variety of human pathologies and in plants severely affects growth, development and responses to stress. The activity of E3 ubiquitin ligases marks proteins fated for degradation with chains of the post-translational modifier, ubiquitin. Proteasomal processing of ubiquitinated substrates involves ubiquitin chain recognition, deubiquitination, ATP-mediated unfolding and translocation, and proteolytic digestion. This complex series of steps is made possible not only by the many specialised subunits of the 1.5 MDa proteasome complex but also by a range of accessory proteins that are recruited to the proteasome. A surprising class of accessory proteins are members of the HECT-type family of ubiquitin ligases that utilise a unique mechanism for post-translational attachment of ubiquitin to their substrates. So why do proteasomes that already contain all the necessary machinery to recognise ubiquitinated substrates, harbour HECT ligase activity? It is now clear that some ubiquitin ligases physically relay their substrates to proteasome-associated HECT ligases, which prevent substrate stalling at the proteasome. Moreover, HECT ligases ubiquitinate proteasome subunits, thereby modifying the proteasome's ability to recognise substrates. They may therefore enable proteasomes to be both non-specific and extraordinarily selective in a complex substrate environment. Understanding the relationship between the proteasome and accessory HECT ligases will reveal how the proteasome controls so many diverse plant developmental and stress responses.
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Affiliation(s)
- Zhishuo Wang
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Steven H Spoel
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
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3
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Abstract
The 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal "processor" for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.
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Affiliation(s)
- Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, 02215, Massachusetts, USA. .,School of Physics, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
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4
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Park YJ, Jang MJ. Blue Light Induced Edible Mushroom ( Lentinula edodes) Proteomic Analysis. J Fungi (Basel) 2020; 6:jof6030127. [PMID: 32781608 PMCID: PMC7558539 DOI: 10.3390/jof6030127] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/24/2020] [Accepted: 08/05/2020] [Indexed: 11/17/2022] Open
Abstract
Blue light is an important environmental factor that induces mushroom growth and morphological changes. In this study, after confirming the morphological difference between Lentinula edodes (LE) under blue light condition (BL) and lightless condition (LL), the increase and decrease in LE protein and the expression of RNA of each protein were confirmed under each condition. LE specimens grown in BL and LL were identified by 253 spots in BL through 2D electrophoresis and LC-MSMS analysis, and 22 types of proteins were identified. It was confirmed that 14 types of proteins showed reduced expression in BL compared to LL. On the other hand, eight kinds of proteins with increased expression in blue light compared to LL were identified. As a result of confirming the difference from the expression pattern in 2D electrophoresis through Quantitative Real-Time PCR, it was confirmed that the expression pattern of the two proteins showed a difference. Therefore, this study will be a key study on the changes in mushroom morphology induced by blue light and the proteins that induce it.
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5
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Larrieu D, Brunet M, Vargas C, Hanoun N, Ligat L, Dagnon L, Lulka H, Pommier RM, Selves J, Jády BE, Bartholin L, Cordelier P, Dufresne M, Torrisani J. The E3 ubiquitin ligase TRIP12 participates in cell cycle progression and chromosome stability. Sci Rep 2020; 10:789. [PMID: 31964993 PMCID: PMC6972862 DOI: 10.1038/s41598-020-57762-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 01/03/2020] [Indexed: 12/29/2022] Open
Abstract
Several studies have linked the E3 ubiquitin ligase TRIP12 (Thyroid hormone Receptor Interacting Protein 12) to the cell cycle. However, the regulation and the implication of this protein during the cell cycle are largely unknown. In this study, we show that TRIP12 expression is regulated during the cell cycle, which correlates with its nuclear localization. We identify an euchromatin-binding function of TRIP12 mediated by a N-terminal intrinsically disordered region. We demonstrate the functional implication of TRIP12 in the mitotic entry by controlling the duration of DNA replication that is independent from its catalytic activity. We also show the requirement of TRIP12 in the mitotic progression and chromosome stability. Altogether, our findings show that TRIP12 is as a new chromatin-associated protein with several implications in the cell cycle progression and in the maintenance of genome integrity.
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Affiliation(s)
- D Larrieu
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - M Brunet
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - C Vargas
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - N Hanoun
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - L Ligat
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - L Dagnon
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - H Lulka
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - R M Pommier
- Université de Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, Lyon, 69008, France
| | - J Selves
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - B E Jády
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, Centre de Biologie Intégrative, Université Toulouse III-Paul Sabatier, Toulouse, Cedex 9, France
| | - L Bartholin
- Université de Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, Lyon, 69008, France
| | - P Cordelier
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - M Dufresne
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France
| | - J Torrisani
- Université de Toulouse, INSERM, Université Toulouse III-Paul Sabatier, Centre de Recherches en Cancérologie de Toulouse, Toulouse, France.
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Finley D, Prado MA. The Proteasome and Its Network: Engineering for Adaptability. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a033985. [PMID: 30833452 DOI: 10.1101/cshperspect.a033985] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The proteasome, the most complex protease known, degrades proteins that have been conjugated to ubiquitin. It faces the unique challenge of acting enzymatically on hundreds and perhaps thousands of structurally diverse substrates, mechanically unfolding them from their native state and translocating them vectorially from one specialized compartment of the enzyme to another. Moreover, substrates are modified by ubiquitin in myriad configurations of chains. The many unusual design features of the proteasome may have evolved in part to endow this enzyme with a robust ability to process substrates regardless of their identity. The proteasome plays a major role in preserving protein homeostasis in the cell, which requires adaptation to a wide variety of stress conditions. Modulation of proteasome function is achieved through a large network of proteins that interact with it dynamically, modify it enzymatically, or fine-tune its levels. The resulting adaptability of the proteasome, which is unique among proteases, enables cells to control the output of the ubiquitin-proteasome pathway on a global scale.
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Affiliation(s)
- Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Miguel A Prado
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
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7
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Coux O, Zieba BA, Meiners S. The Proteasome System in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1233:55-100. [DOI: 10.1007/978-3-030-38266-7_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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8
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Furniss JJ, Grey H, Wang Z, Nomoto M, Jackson L, Tada Y, Spoel SH. Proteasome-associated HECT-type ubiquitin ligase activity is required for plant immunity. PLoS Pathog 2018; 14:e1007447. [PMID: 30458055 PMCID: PMC6286022 DOI: 10.1371/journal.ppat.1007447] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/07/2018] [Accepted: 10/31/2018] [Indexed: 11/19/2022] Open
Abstract
Regulated degradation of proteins by the 26S proteasome plays important roles in maintenance and signalling in eukaryotic cells. Proteins are marked for degradation by the action of E3 ligases that site-specifically modify their substrates by adding chains of ubiquitin. Innate immune signalling in plants is deeply reliant on the ubiquitin-26S proteasome system. While progress has been made in understanding substrate ubiquitination during plant immunity, how these substrates are processed upon arrival at the proteasome remains unclear. Here we show that specific members of the HECT domain-containing family of ubiquitin protein ligases (UPL) play important roles in proteasomal substrate processing during plant immunity. Mutations in UPL1, UPL3 and UPL5 significantly diminished immune responses activated by the immune hormone salicylic acid (SA). In depth analyses of upl3 mutants indicated that these plants were impaired in reprogramming of nearly the entire SA-induced transcriptome and failed to establish immunity against a hemi-biotrophic pathogen. UPL3 was found to physically interact with the regulatory particle of the proteasome and with other ubiquitin-26S proteasome pathway components. In agreement, we demonstrate that UPL3 enabled proteasomes to form polyubiquitin chains, thereby regulating total cellular polyubiquitination levels. Taken together, our findings suggest that proteasome-associated ubiquitin ligase activity of UPL3 promotes proteasomal processivity and is indispensable for development of plant immunity.
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Affiliation(s)
- James J. Furniss
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Heather Grey
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Zhishuo Wang
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Mika Nomoto
- The Center for Gene Research, Division of Biological Science, Nagoya University, Nagoya, Japan
| | - Lorna Jackson
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Yasuomi Tada
- The Center for Gene Research, Division of Biological Science, Nagoya University, Nagoya, Japan
| | - Steven H. Spoel
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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9
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Marquez-Lona EM, Torres-Machorro AL, Gonzales FR, Pillus L, Patrick GN. Phosphorylation of the 19S regulatory particle ATPase subunit, Rpt6, modifies susceptibility to proteotoxic stress and protein aggregation. PLoS One 2017; 12:e0179893. [PMID: 28662109 PMCID: PMC5491056 DOI: 10.1371/journal.pone.0179893] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 06/06/2017] [Indexed: 12/22/2022] Open
Abstract
The ubiquitin proteasome system (UPS) is a highly conserved and tightly regulated biochemical pathway that degrades the majority of proteins in eukaryotic cells. Importantly, the UPS is responsible for counteracting altered protein homeostasis induced by a variety of proteotoxic stresses. We previously reported that Rpt6, the ATPase subunit of the 19S regulatory particle (RP) of the 26S proteasome, is phosphorylated in mammalian neurons at serine 120 in response to neuronal activity. Furthermore, we found that Rpt6 S120 phosphorylation, which regulates the activity and distribution of proteasomes in neurons, is relevant for proteasome-dependent synaptic remodeling and function. To better understand the role of proteasome phosphorylation, we have constructed models of altered Rpt6 phosphorylation in S. cerevisiae by introducing chromosomal point mutations that prevent or mimic phosphorylation at the conserved serine (S119). We find that mutants which prevent Rpt6 phosphorylation at this site (rpt6-S119A), had increased susceptibility to proteotoxic stress, displayed abnormal morphology and had reduced proteasome activity. Since impaired proteasome function has been linked to the aggregation of toxic proteins including the Huntington’s disease (HD) related huntingtin (Htt) protein with expanded polyglutamine repeats, we evaluated the extent of Htt aggregation in our phospho-dead (rpt6-S119A) and phospho-mimetic (rpt6-S119D) mutants. We showed Htt103Q aggregate size to be significantly larger in rpt6-S119A mutants compared to wild-type or rpt6-S119D strains. Furthermore, we observed that phosphorylation of endogenous Rpt6 at S119 is increased in response to various stress conditions. Together, these data suggest that Rpt6 phosphorylation at S119 may play an important function in proteasome-dependent relief of proteotoxic stress that can be critical in protein aggregation pathologies.
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Affiliation(s)
- Esther Magdalena Marquez-Lona
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Ana Lilia Torres-Machorro
- Section of Molecular Biology and UCSD Moores Cancer Center, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Frankie R. Gonzales
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Lorraine Pillus
- Section of Molecular Biology and UCSD Moores Cancer Center, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Gentry N. Patrick
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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10
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Jöhnk B, Bayram Ö, Abelmann A, Heinekamp T, Mattern DJ, Brakhage AA, Jacobsen ID, Valerius O, Braus GH. SCF Ubiquitin Ligase F-box Protein Fbx15 Controls Nuclear Co-repressor Localization, Stress Response and Virulence of the Human Pathogen Aspergillus fumigatus. PLoS Pathog 2016; 12:e1005899. [PMID: 27649508 PMCID: PMC5029927 DOI: 10.1371/journal.ppat.1005899] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 08/26/2016] [Indexed: 01/27/2023] Open
Abstract
F-box proteins share the F-box domain to connect substrates of E3 SCF ubiquitin RING ligases through the adaptor Skp1/A to Cul1/A scaffolds. F-box protein Fbx15 is part of the general stress response of the human pathogenic mold Aspergillus fumigatus. Oxidative stress induces a transient peak of fbx15 expression, resulting in 3x elevated Fbx15 protein levels. During non-stress conditions Fbx15 is phosphorylated and F-box mediated interaction with SkpA preferentially happens in smaller subpopulations in the cytoplasm. The F-box of Fbx15 is required for an appropriate oxidative stress response, which results in rapid dephosphorylation of Fbx15 and a shift of the cellular interaction with SkpA to the nucleus. Fbx15 binds SsnF/Ssn6 as part of the RcoA/Tup1-SsnF/Ssn6 co-repressor and is required for its correct nuclear localization. Dephosphorylated Fbx15 prevents SsnF/Ssn6 nuclear localization and results in the derepression of gliotoxin gene expression. fbx15 deletion mutants are unable to infect immunocompromised mice in a model for invasive aspergillosis. Fbx15 has a novel dual molecular function by controlling transcriptional repression and being part of SCF E3 ubiquitin ligases, which is essential for stress response, gliotoxin production and virulence in the opportunistic human pathogen A. fumigatus. The opportunistic human fungal pathogen Aspergillus fumigatus is the most prevalent cause for severe fungal infections in immunocompromised hosts. A major virulence factor of A. fumigatus is its ability to rapidly adapt to host conditions during infection. The rapid response to environmental changes underlies a well-balanced system of production and degradation of proteins. The degradation of specific target proteins is mediated by ubiquitin-protein ligases (E3), which mark their target proteins with ubiquitin for proteasomal degradation. Multisubunit SCF Cullin1 Ring ligases (CRL) are E3 ligases where the F-box subunit functions as a substrate-specificity determining adaptor. A comprehensive control of protein production includes global co-repressors as the conserved Ssn6(SsnF)-Tup1(RcoA) complex, which reduces transcription on multiple levels. We have identified a novel connection between protein degradation and synthesis through an F-box protein. Fbx15 can be incorporated into SCF E3 ubiquitin ligases and controls upon stress the nuclear localization of the SsnF. Fbx15 plays a critical role for A. fumigatus adaptation and is essential for virulence in a murine infection model. Fbx15 is a fungal-specific protein and therefore a potential target for future drug development.
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Affiliation(s)
- Bastian Jöhnk
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Özgür Bayram
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
- Department of Biology, Maynooth University, National University of Ireland, Maynooth, County Kildare, Ireland
| | - Anja Abelmann
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Thorsten Heinekamp
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Derek J. Mattern
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Ilse D. Jacobsen
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
- * E-mail:
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11
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Ha SW, Ju D, Hao W, Xie Y. Rapidly Translated Polypeptides Are Preferred Substrates for Cotranslational Protein Degradation. J Biol Chem 2016; 291:9827-34. [PMID: 26961882 DOI: 10.1074/jbc.m116.716175] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Indexed: 11/06/2022] Open
Abstract
Nascent polypeptides are degraded by the proteasome concurrently with their synthesis on the ribosome. This process, called cotranslational protein degradation (CTPD), has been observed for years, but the underlying mechanisms remain poorly understood. Equally unclear are the identities of cellular proteins genuinely subjected to CTPD. Here we report the identification of CTPD substrates in the yeast Saccharomyces cerevisiae via a quantitative proteomic analysis. We compared the abundance of individual ribosome-bound nascent chains between a wild type strain and a mutant defective in CTPD. Of 1,422 proteins acquired from the proteomic analysis, 289 species are efficient CTPD substrates, with >30% of their nascent chains degraded cotranslationally. We found that proteins involved in translation, ribosome biogenesis, nuclear transport, and amino acid metabolism are more likely to be targeted for CTPD. There is a strong correlation between CTPD and the translation efficiency. CTPD occurs preferentially to rapidly translated polypeptides. CTPD is also influenced by the protein sequence length; longer polypeptides are more susceptible to CTPD. In addition, proteins with N-terminal disorder have a higher probability of being degraded cotranslationally. Interestingly, the CTPD efficiency is not related to the half-lives of mature proteins. These results for the first time indicate an inverse correlation between CTPD and cotranslational folding on a proteome scale. The implications of this study with respect to the physiological significance of CTPD are discussed.
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Affiliation(s)
- Seung-Wook Ha
- From the Karmanos Cancer Institute, Department of Oncology, School of Medicine and
| | - Donghong Ju
- From the Karmanos Cancer Institute, Department of Oncology, School of Medicine and
| | - Weilong Hao
- the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48201
| | - Youming Xie
- From the Karmanos Cancer Institute, Department of Oncology, School of Medicine and
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12
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Boomsma W, Nielsen SV, Lindorff-Larsen K, Hartmann-Petersen R, Ellgaard L. Bioinformatics analysis identifies several intrinsically disordered human E3 ubiquitin-protein ligases. PeerJ 2016; 4:e1725. [PMID: 26966660 PMCID: PMC4782732 DOI: 10.7717/peerj.1725] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/02/2016] [Indexed: 12/28/2022] Open
Abstract
The ubiquitin-proteasome system targets misfolded proteins for degradation. Since the accumulation of such proteins is potentially harmful for the cell, their prompt removal is important. E3 ubiquitin-protein ligases mediate substrate ubiquitination by bringing together the substrate with an E2 ubiquitin-conjugating enzyme, which transfers ubiquitin to the substrate. For misfolded proteins, substrate recognition is generally delegated to molecular chaperones that subsequently interact with specific E3 ligases. An important exception is San1, a yeast E3 ligase. San1 harbors extensive regions of intrinsic disorder, which provide both conformational flexibility and sites for direct recognition of misfolded targets of vastly different conformations. So far, no mammalian ortholog of San1 is known, nor is it clear whether other E3 ligases utilize disordered regions for substrate recognition. Here, we conduct a bioinformatics analysis to examine >600 human and S. cerevisiae E3 ligases to identify enzymes that are similar to San1 in terms of function and/or mechanism of substrate recognition. An initial sequence-based database search was found to detect candidates primarily based on the homology of their ordered regions, and did not capture the unique disorder patterns that encode the functional mechanism of San1. However, by searching specifically for key features of the San1 sequence, such as long regions of intrinsic disorder embedded with short stretches predicted to be suitable for substrate interaction, we identified several E3 ligases with these characteristics. Our initial analysis revealed that another remarkable trait of San1 is shared with several candidate E3 ligases: long stretches of complete lysine suppression, which in San1 limits auto-ubiquitination. We encode these characteristic features into a San1 similarity-score, and present a set of proteins that are plausible candidates as San1 counterparts in humans. In conclusion, our work indicates that San1 is not a unique case, and that several other yeast and human E3 ligases have sequence properties that may allow them to recognize substrates by a similar mechanism as San1.
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Affiliation(s)
- Wouter Boomsma
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Sofie V Nielsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Kresten Lindorff-Larsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Rasmus Hartmann-Petersen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Lars Ellgaard
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
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13
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Aguileta MA, Korac J, Durcan TM, Trempe JF, Haber M, Gehring K, Elsasser S, Waidmann O, Fon EA, Husnjak K. The E3 ubiquitin ligase parkin is recruited to the 26 S proteasome via the proteasomal ubiquitin receptor Rpn13. J Biol Chem 2015; 290:7492-505. [PMID: 25666615 DOI: 10.1074/jbc.m114.614925] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in the Park2 gene, encoding the RING-HECT hybrid E3 ubiquitin ligase parkin, are responsible for a common familial form of Parkinson disease. By mono- and polyubiquitinating target proteins, parkin regulates various cellular processes, including degradation of proteins within the 26 S proteasome, a large multimeric degradation machine. In our attempt to further elucidate the function of parkin, we have identified the proteasomal ubiquitin receptor Rpn13/ADRM1 as a parkin-interacting protein. We show that the N-terminal ubiquitin-like (Ubl) domain of parkin binds directly to the pleckstrin-like receptor for ubiquitin (Pru) domain within Rpn13. Using mutational analysis and NMR, we find that Pru binding involves the hydrophobic patch surrounding Ile-44 in the parkin Ubl, a region that is highly conserved between ubiquitin and Ubl domains. However, compared with ubiquitin, the parkin Ubl exhibits greater than 10-fold higher affinity for the Pru domain. Moreover, knockdown of Rpn13 in cells increases parkin levels and abrogates parkin recruitment to the 26 S proteasome, establishing Rpn13 as the major proteasomal receptor for parkin. In contrast, silencing Rpn13 did not impair parkin recruitment to mitochondria or parkin-mediated mitophagy upon carbonyl cyanide m-chlorophenyl hydrazone-induced mitochondrial depolarization. However, it did delay the clearance of mitochondrial proteins (TIM23, TIM44, and TOM20) and enhance parkin autoubiquitination. Taken together, these findings implicate Rpn13 in linking parkin to the 26 S proteasome and regulating the clearance of mitochondrial proteins during mitophagy.
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Affiliation(s)
- Miguel A Aguileta
- From the McGill Parkinson Program and Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Jelena Korac
- the School of Medicine, University of Split, 21000 Split, Croatia
| | - Thomas M Durcan
- From the McGill Parkinson Program and Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Jean-François Trempe
- the Department of Biochemistry, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - Michael Haber
- From the McGill Parkinson Program and Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Kalle Gehring
- the Department of Biochemistry, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - Suzanne Elsasser
- the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, and
| | - Oliver Waidmann
- Goethe University Medical School, D-60590 Frankfurt am Main, Germany
| | - Edward A Fon
- From the McGill Parkinson Program and Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Koraljka Husnjak
- Goethe University Medical School, D-60590 Frankfurt am Main, Germany
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14
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Schmidt M, Finley D. Regulation of proteasome activity in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:13-25. [PMID: 23994620 DOI: 10.1016/j.bbamcr.2013.08.012] [Citation(s) in RCA: 328] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 12/13/2022]
Abstract
The ubiquitin-proteasome system (UPS) is the primary selective degradation system in the nuclei and cytoplasm of eukaryotic cells, required for the turnover of myriad soluble proteins. The hundreds of factors that comprise the UPS include an enzymatic cascade that tags proteins for degradation via the covalent attachment of a poly-ubiquitin chain, and a large multimeric enzyme that degrades ubiquitinated proteins, the proteasome. Protein degradation by the UPS regulates many pathways and is a crucial component of the cellular proteostasis network. Dysfunction of the ubiquitination machinery or the proteolytic activity of the proteasome is associated with numerous human diseases. In this review we discuss the contributions of the proteasome to human pathology, describe mechanisms that regulate the proteolytic capacity of the proteasome, and discuss strategies to modulate proteasome function as a therapeutic approach to ameliorate diseases associated with altered UPS function. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
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Affiliation(s)
- Marion Schmidt
- Albert Einstein College of Medicine, Department of Biochemistry, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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15
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Tsuchiya H, Tanaka K, Saeki Y. The parallel reaction monitoring method contributes to a highly sensitive polyubiquitin chain quantification. Biochem Biophys Res Commun 2013; 436:223-9. [DOI: 10.1016/j.bbrc.2013.05.080] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 05/21/2013] [Indexed: 10/26/2022]
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16
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Transfer of Ho endonuclease and Ufo1 to the proteasome by the UbL-UbA shuttle protein, Ddi1, analysed by complex formation in vitro. PLoS One 2012; 7:e39210. [PMID: 22815701 PMCID: PMC3398040 DOI: 10.1371/journal.pone.0039210] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 05/21/2012] [Indexed: 01/20/2023] Open
Abstract
The F-box protein, Ufo1, recruits Ho endonuclease to the SCFUfo1 complex for ubiquitylation. Both ubiquitylated Ho and Ufo1 are transferred by the UbL-UbA protein, Ddi1, to the 19S Regulatory Particle (RP) of the proteasome for degradation. The Ddi1-UbL domain binds Rpn1 of the 19S RP, the Ddi1-UbA domain binds ubiquitin chains on the degradation substrate. Here we used complex reconstitution in vitro to identify stages in the transfer of Ho and Ufo1 from the SCFUfo1 complex to the proteasome. We report SCFUfo1 complex at the proteasome formed in the presence of Ho. Subsequently Ddi1 is recruited to this complex by interaction between the Ddi1-UbL domain and Ufo1. The core of Ddi1 binds both Ufo1 and Rpn1; this interaction confers specificity of SCFUfo1 for Ddi1. The substrate-shield model predicts that Ho would protect Ufo1 from degradation and we find that Ddi1 binds Ho, Ufo1, and Rpn1 simultaneously forming a complex for transfer of Ho to the 19S RP. In contrast, in the absence of Ho, Rpn1 displaces Ufo1 from Ddi1 indicating a higher affinity of the Ddi1-UbL for the 19S RP. However, at high Rpn1 levels there is synergistic binding of Ufo1 to Ddi1 that is dependent on the Ddi1-UbA domain. Our interpretation is that in the absence of substrate, the Ddi1-UbL binds Rpn1 while the Ddi1-UbA binds ubiquitin chains on Ufo1. This would promote degradation of Ufo1 and disassembly of SCFUfo1 complexes.
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17
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Generation of free ubiquitin chains is up-regulated in stress and facilitated by the HECT domain ubiquitin ligases UFD4 and HUL5. Biochem J 2012; 444:611-7. [DOI: 10.1042/bj20111840] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Polyubiquitin chains serve a variety of physiological roles. Typically the chains are bound covalently to a protein substrate and in many cases target it for degradation by the 26S proteasome. However, several studies have demonstrated the existence of free polyubiquitin chains which are not linked to a specific substrate. Several physiological functions have been attributed to these chains, among them playing a role in signal transduction and serving as storage of ubiquitin for utilization under stress. In the present study, we have established a system for the detection of free ubiquitin chains and monitoring their level under changing conditions. Using this system, we show that UFD4 (ubiquitin fusion degradation 4), a HECT (homologous with E6-AP C-terminus) domain ubiquitin ligase, is involved in free chain generation. We also show that generation of these chains is stimulated in response to a variety of stresses, particularly those caused by DNA damage. However, it appears that the stress-induced synthesis of free chains is catalysed by a different ligase, HUL5 (HECT ubiquitin ligase 5), which is also a HECT domain E3.
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18
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Abstract
The posttranslational modification with ubiquitin, a process referred to as ubiquitylation, controls almost every process in cells. Ubiquitin can be attached to substrate proteins as a single moiety or in the form of polymeric chains in which successive ubiquitin molecules are connected through specific isopeptide bonds. Reminiscent of a code, the various ubiquitin modifications adopt distinct conformations and lead to different outcomes in cells. Here, we discuss the structure, assembly, and function of this ubiquitin code.
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Affiliation(s)
- David Komander
- Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom.
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19
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Hul5 HECT ubiquitin ligase plays a major role in the ubiquitylation and turnover of cytosolic misfolded proteins. Nat Cell Biol 2011; 13:1344-52. [PMID: 21983566 PMCID: PMC4961474 DOI: 10.1038/ncb2343] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 08/16/2011] [Indexed: 11/10/2022]
Abstract
Cellular toxicity introduced by protein misfolding threatens cell fitness and viability. Failure to eliminate these polypeptides is associated with numerous aggregation diseases. Several protein quality control mechanisms degrade non-native proteins by the ubiquitin proteasome system. Here, we use quantitative mass spectrometry to demonstrate that heat-shock triggers a large increase of ubiquitylation associated with misfolding of cytosolic proteins. We discover that the Hul5 HECT ubiquitin ligase participates in this heat-shock stress response. Hul5 is required to maintain cell fitness after heat-shock and to degrade short-lived misfolded proteins. In addition, localization of Hul5 in the cytoplasm is important for its quality control function. We identify potential Hul5 substrates in heat-shock and physiological conditions to reveal that Hul5 is required for ubiquitylation of low solubility cytosolic proteins including the Pin3 prion-like protein. These findings indicate that Hul5 is involved in a cytosolic protein quality control pathway that targets misfolded proteins for degradation.
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20
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Varshavsky A. The N-end rule pathway and regulation by proteolysis. Protein Sci 2011; 20:1298-345. [PMID: 21633985 PMCID: PMC3189519 DOI: 10.1002/pro.666] [Citation(s) in RCA: 517] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 05/16/2011] [Accepted: 05/18/2011] [Indexed: 01/12/2023]
Abstract
The N-end rule relates the regulation of the in vivo half-life of a protein to the identity of its N-terminal residue. Degradation signals (degrons) that are targeted by the N-end rule pathway include a set called N-degrons. The main determinant of an N-degron is a destabilizing N-terminal residue of a protein. In eukaryotes, the N-end rule pathway is a part of the ubiquitin system and consists of two branches, the Ac/N-end rule and the Arg/N-end rule pathways. The Ac/N-end rule pathway targets proteins containing N(α) -terminally acetylated (Nt-acetylated) residues. The Arg/N-end rule pathway recognizes unacetylated N-terminal residues and involves N-terminal arginylation. Together, these branches target for degradation a majority of cellular proteins. For example, more than 80% of human proteins are cotranslationally Nt-acetylated. Thus most proteins harbor a specific degradation signal, termed (Ac)N-degron, from the moment of their birth. Specific N-end rule pathways are also present in prokaryotes and in mitochondria. Enzymes that produce N-degrons include methionine-aminopeptidases, caspases, calpains, Nt-acetylases, Nt-amidases, arginyl-transferases and leucyl-transferases. Regulated degradation of specific proteins by the N-end rule pathway mediates a legion of physiological functions, including the sensing of heme, oxygen, and nitric oxide; selective elimination of misfolded proteins; the regulation of DNA repair, segregation and condensation; the signaling by G proteins; the regulation of peptide import, fat metabolism, viral and bacterial infections, apoptosis, meiosis, spermatogenesis, neurogenesis, and cardiovascular development; and the functioning of adult organs, including the pancreas and the brain. Discovered 25 years ago, this pathway continues to be a fount of biological insights.
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Affiliation(s)
- Alexander Varshavsky
- 1Division of Biology, California Institute of Technology, Pasadena, California 91125.
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21
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Xie Y. Feedback regulation of proteasome gene expression and its implications in cancer therapy. Cancer Metastasis Rev 2011; 29:687-93. [PMID: 20835843 DOI: 10.1007/s10555-010-9255-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proteasomal protein degradation is one of the major regulatory mechanisms in the cell. Aberrant proteasome activity is directly related to the pathogenesis of many human diseases including cancers. How proteasome homeostasis is controlled is a fundamental question toward our understanding of proteasome dysregulation in cancer cells. The recent discovery of the Rpn4-proteasome negative feedback circuit provides mechanistic insight into the regulation of proteasome gene expression. This finding also has important implications in cancer therapy that uses small molecule inhibitors to target the proteasome.
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Affiliation(s)
- Youming Xie
- Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, 110 E Warren Ave, Detroit, MI 48201, USA.
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22
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Mandal AK, Theodoraki MA, Nillegoda NB, Caplan AJ. Role of molecular chaperones in biogenesis of the protein kinome. Methods Mol Biol 2011; 787:75-81. [PMID: 21898228 DOI: 10.1007/978-1-61779-295-3_6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Molecular chaperones promote polypeptide folding in cells by protecting newly made and otherwise misfolded proteins against aggregation or degradation by the ubiquitin proteasome pathway. The roles of Saccharomyces cerevisiae Cdc37 and Ydj1 molecular chaperones are described in this chapter. We focus on biogenesis of protein kinases that require several different molecular chaperones for their proper folding. Specific among these is Cdc37, which binds directly to its kinase clients either during or shortly after translation and protects them against rapid proteasomal degradation. Ydj1 has a similar role, but is less specific for protein kinases in its role as a molecular chaperone. The method that we describe uses pulse chase and immunoprecipitation to analyze the fate of newly made proteins. Two kinetically distinct pathways of degradation can be discerned using this methodology that is dependent on the presence of an Hsp90 inhibitor or occurs in mutants of the molecular chaperones under study. The first is "zero-point" degradation that occurs either during or immediately after translation. The second is a slower pathway, where the half-life of kinase is approximately 20 min after translation.
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Affiliation(s)
- Atin K Mandal
- Department of Biology, City College New York, New York, NY, USA
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23
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Metzger MB, Weissman AM. Working on a chain: E3s ganging up for ubiquitylation. Nat Cell Biol 2010; 12:1124-6. [PMID: 21124306 DOI: 10.1038/ncb1210-1124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Hwang CS, Shemorry A, Auerbach D, Varshavsky A. The N-end rule pathway is mediated by a complex of the RING-type Ubr1 and HECT-type Ufd4 ubiquitin ligases. Nat Cell Biol 2010; 12:1177-85. [PMID: 21076411 PMCID: PMC3003441 DOI: 10.1038/ncb2121] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 10/18/2010] [Indexed: 02/07/2023]
Abstract
Substrates of the N-end rule pathway are recognized by the Ubr1 E3 ubiquitin ligase through their destabilizing N-terminal residues. Our previous work showed that the Ubr1 E3 and the Ufd4 E3 co-target an internal degron of the Mgt1 DNA repair protein. Ufd4 is an E3 of the ubiquitin-fusion degradation (UFD) pathway that recognizes an N-terminal ubiquitin moiety. Here we report that the RING-type Ubr1 E3 and the HECT-type Ufd4 E3 interact, both physically and functionally. Although Ubr1 can recognize and polyubiquitylate an N-end rule substrate in the absence of Ufd4, the Ubr1-Ufd4 complex is more processive in that it produces a longer substrate-linked polyubiquitin chain. Conversely, Ubr1 can function as a polyubiquitylation-enhancing component of the Ubr1-Ufd4 complex in its targeting of UFD substrates. We also found that Ubr1 can recognize the N-terminal ubiquitin moiety. These and related advances unify two proteolytic systems that have been studied separately over two decades.
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Affiliation(s)
- Cheol-Sang Hwang
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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25
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Xie Y. Structure, Assembly and Homeostatic Regulation of the 26S Proteasome. J Mol Cell Biol 2010; 2:308-17. [DOI: 10.1093/jmcb/mjq030] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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26
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Gorbea C, Pratt G, Ustrell V, Bell R, Sahasrabudhe S, Hughes RE, Rechsteiner M. A protein interaction network for Ecm29 links the 26 S proteasome to molecular motors and endosomal components. J Biol Chem 2010; 285:31616-33. [PMID: 20682791 DOI: 10.1074/jbc.m110.154120] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ecm29 is a 200-kDa HEAT repeat protein that binds the 26 S proteasome. Genome-wide two-hybrid screens and mass spectrometry have identified molecular motors, endosomal components, and ubiquitin-proteasome factors as Ecm29-interacting proteins. The C-terminal half of human Ecm29 binds myosins and kinesins; its N-terminal region binds the endocytic proteins, Vps11, Rab11-FIP4, and rabaptin. Whereas full-length FLAG-Ecm29, its C-terminal half, and a small central fragment of Ecm29 remain bound to glycerol-gradient-separated 26 S proteasomes, the N-terminal half of Ecm29 does not. Confocal microscopy showed that Ecm-26 S proteasomes are present on flotillin-positive endosomes, but they are virtually absent from caveolin- and clathrin-decorated endosomes. Expression of the small central fragment of Ecm29 markedly reduces proteasome association with flotillin-positive endosomes. Identification of regions within Ecm29 capable of binding molecular motors, endosomal proteins, and the 26 S proteasome supports the hypothesis that Ecm29 serves as an adaptor for coupling 26 S proteasomes to specific cellular compartments.
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Affiliation(s)
- Carlos Gorbea
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
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27
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Nillegoda NB, Theodoraki MA, Mandal AK, Mayo KJ, Ren HY, Sultana R, Wu K, Johnson J, Cyr DM, Caplan AJ. Ubr1 and Ubr2 function in a quality control pathway for degradation of unfolded cytosolic proteins. Mol Biol Cell 2010; 21:2102-16. [PMID: 20462952 PMCID: PMC2893976 DOI: 10.1091/mbc.e10-02-0098] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Ubr1 and Ubr2 ubiquitin ligases are shown to promote degradation of misfolded cytosolic polypeptides in vivo and in a purified system in association with Hsp70. Quality control systems facilitate polypeptide folding and degradation to maintain protein homeostasis. Molecular chaperones promote folding, whereas the ubiquitin/proteasome system mediates degradation. We show here that Saccharomyces cerevisiae Ubr1 and Ubr2 ubiquitin ligases promote degradation of unfolded or misfolded cytosolic polypeptides. Ubr1 also catalyzes ubiquitinylation of denatured but not native luciferase in a purified system. This activity is based on the direct interaction of denatured luciferase with Ubr1, although Hsp70 stimulates polyubiquitinylation of the denatured substrate. We also report that loss of Ubr1 and Ubr2 function suppressed the growth arrest phenotype resulting from chaperone mutation. This correlates with increased protein kinase maturation and indicates partitioning of foldable conformers toward the proteasome. Our findings, based on the efficiency of this quality control system, suggest that the cell trades growth potential to avert the potential toxicity associated with accumulation of unfolded or misfolded proteins. Ubr1 and Ubr2 therefore represent E3 components of a novel quality control pathway for proteins synthesized on cytosolic ribosomes.
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Affiliation(s)
- Nadinath B Nillegoda
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY 10029, USA
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28
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Abstract
The proteasome is an intricate molecular machine, which serves to degrade proteins following their conjugation to ubiquitin. Substrates dock onto the proteasome at its 19-subunit regulatory particle via a diverse set of ubiquitin receptors and are then translocated into an internal chamber within the 28-subunit proteolytic core particle (CP), where they are hydrolyzed. Substrate is threaded into the CP through a narrow gated channel, and thus translocation requires unfolding of the substrate. Six distinct ATPases in the regulatory particle appear to form a ring complex and to drive unfolding as well as translocation. ATP-dependent, degradation-coupled deubiquitination of the substrate is required both for efficient substrate degradation and for preventing the degradation of the ubiquitin tag. However, the proteasome also contains deubiquitinating enzymes (DUBs) that can remove ubiquitin before substrate degradation initiates, thus allowing some substrates to dissociate from the proteasome and escape degradation. Here we examine the key elements of this molecular machine and how they cooperate in the processing of proteolytic substrates.
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Affiliation(s)
- Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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29
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Marques AJ, Palanimurugan R, Matias AC, Ramos PC, Dohmen RJ. Catalytic mechanism and assembly of the proteasome. Chem Rev 2009; 109:1509-36. [PMID: 19265443 DOI: 10.1021/cr8004857] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- António J Marques
- Institute for Genetics, University of Cologne, Zulpicher Strasse 47, D-50674 Cologne, Germany
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30
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Two proteolytic pathways regulate DNA repair by cotargeting the Mgt1 alkylguanine transferase. Proc Natl Acad Sci U S A 2009; 106:2142-7. [PMID: 19164530 DOI: 10.1073/pnas.0812316106] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
O(6)-methylguanine (O(6)meG) and related modifications of guanine in double-stranded DNA are functionally severe lesions that can be produced by many alkylating agents, including N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a potent carcinogen. O(6)meG is repaired through its demethylation by the O(6)-alkylguanine-DNA alkyltransferase (AGT). This protein is called Mgmt (or MGMT) in mammals and Mgt1 in the yeast Saccharomyces cerevisiae. AGT proteins remove methyl and other alkyl groups from an alkylated O(6) in guanine by transferring the adduct to an active-site cysteine residue. The resulting S-alkyl-Cys of AGT is not restored back to Cys, so repair proteins of this kind can act only once. We report here that S. cerevisiae Mgt1 is cotargeted for degradation, through a degron near its N terminus, by 2 ubiquitin-mediated proteolytic systems, the Ubr1/Rad6-dependent N-end rule pathway and the Ufd4/Ubc4-dependent ubiquitin fusion degradation (UFD) pathway. The cotargeting of Mgt1 by these pathways is synergistic, in that it increases not only the yield of polyubiquitylated Mgt1, but also the processivity of polyubiquitylation. The N-end rule and UFD pathways comediate both the constitutive and MNNG-accelerated degradation of Mgt1. Yeast cells lacking the Ubr1 and Ufd4 ubiquitin ligases were hyperresistant to MNNG but hypersensitive to the toxicity of overexpressed Mgt1. We consider ramifications of this discovery for the control of DNA repair and mechanisms of substrate targeting by the ubiquitin system.
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31
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Baranes-Bachar K, Baranes-Bacher K, Khalaila I, Ivantsiv Y, Lavut A, Voloshin O, Raveh D. New interacting partners of the F-box protein Ufo1 of yeast. Yeast 2008; 25:733-43. [PMID: 18949821 DOI: 10.1002/yea.1615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The yeast F-box protein Ufo1 recruits proteins for ubiquitylation by the SCF ubiquitin ligase complex preparing them for proteasomal degradation. Ufo1 has a role in maintenance of genome stability; its substrates include Ho endonuclease and Rad30 polymerase of error-prone DNA repair. Ufo1 is an unusual F-box protein, as it has three ubiquitin interacting motifs (UIMs). Deletion of the genomic UIMs is lethal; ectopic expression of UFO1 Delta UIMs extends protein half-life and arrests the cell cycle. A whole-genome study employing a TAP tag fused to the C-terminal UIMs did not identify Ufo1-interacting proteins. Here we therefore used stabilized N-terminally tagged Ufo1 Delta UIM as a strategy to identify Ufo1-interacting proteins by mass spectroscopy. We identified proteins that function in transcription, and an indirect interaction with Hsp70 molecular chaperones via the Skp1 adaptor; we also show that Ufo1 interacts with the 19S regulatory particle of the proteasome. Thus, our data augment the current network of known Ufo1 interacting proteins. We show directly that the UIMs are crucial for Ufo1 ubiquitylation in vivo, indicating that they facilitate turnover of SCF Ufo1 complexes. This allows recycling of the core subunits of the SCF complex and cell cycle progression.
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Affiliation(s)
- Keren Baranes-Bachar
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheba, Israel
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32
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Affiliation(s)
- Alexander Varshavsky
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
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Wang X, Xu H, Ju D, Xie Y. Disruption of Rpn4-induced proteasome expression in Saccharomyces cerevisiae reduces cell viability under stressed conditions. Genetics 2008; 180:1945-53. [PMID: 18832351 PMCID: PMC2600933 DOI: 10.1534/genetics.108.094524] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 09/16/2008] [Indexed: 11/18/2022] Open
Abstract
The proteasome homeostasis in Saccharomyces cerevisiae is regulated by a negative feedback circuit in which the transcription activator Rpn4 upregulates the proteasome genes and is rapidly degraded by the assembled proteasome. Previous studies have shown that rpn4Delta cells are sensitive to a variety of stresses. However, the contribution of the loss of Rpn4-induced proteasome expression to the rpn4Delta phenotypes remains unclear because Rpn4 controls numerous genes other than the proteasome genes. Here we construct a yeast strain in which one of the essential proteasome genes, PRE1, is no longer induced by Rpn4. We show that the active proteasome level is lower in this strain than in the wild-type counterpart. Moreover, we demonstrate that loss of Rpn4-induced proteasome expression leads to cell-cycle delay in G2/M and sensitizes cells to various stresses. To our knowledge, this is the first report that explicitly reveals the physiological function of Rpn4-induced proteasome expression. This study also provides a tool for understanding the interactions between proteasome homeostasis and other cellular processes.
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Affiliation(s)
- Xiaogang Wang
- Department of Pathology, Shanghai Medical College, Fudan University, Shanghai 2000032, People's Republic of China
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Park Y, Yoon SK, Yoon JB. The HECT domain of TRIP12 ubiquitinates substrates of the ubiquitin fusion degradation pathway. J Biol Chem 2008; 284:1540-9. [PMID: 19028681 DOI: 10.1074/jbc.m807554200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ubiquitin fusion degradation (UFD) pathway is a proteolytic system conserved in yeast and mammals in which an uncleavable ubiquitin moiety linked to the N terminus of a protein functions as a degradation signal of the fusion protein. Although key components of the UFD pathway in yeast have been identified, the E3 enzyme of the human UFD pathway has not been studied. In this work, we show that TRIP12 is the E3 enzyme of the human UFD pathway. Thus, TRIP12 catalyzes in vitro ubiquitination of UFD substrates in conjunction with E1, E2, and E4 enzymes. Knockdown of TRIP12 stabilizes not only artificial UFD substrates but a physiological substrate UBB+1. Moreover, TRIP12 knockdown reduces UBB+1-induced cell death in human neuroblastoma cells. Surprisingly, complementation of TRIP12 knockdown cells with the TRIP12 HECT domain mostly restores efficient degradation of UFD substrates, indicating that the TRIP12 HECT domain can act as the E3 enzyme for the UFD pathway in human cells. The TRIP12 HECT domain directs ubiquitination of UFD substrates in vitro and can be specifically cross-linked to the ubiquitin moiety of the substrates in vivo, suggesting that the TRIP12 HECT domain possesses a noncovalent ubiquitin-binding site. In addition, we demonstrate that UbDeltaGG, a mutant ubiquitin that cannot be conjugated to other proteins, is a substrate of the TRIP12 HECT domain both in vivo and in vitro, indicating that the C-terminal extension fused to the uncleavable ubiquitin is not required for substrate recognition in the UFD pathway. These results provide new insights into the mechanism of the mammalian UFD pathway and the functional nonequivalence of different HECT domains.
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Affiliation(s)
- Yoon Park
- Department of Biochemistry and Protein Network Research Center, Yonsei University, 134 Shinchon-Dong, Seodaemoon-Gu, Seoul 120-749, Korea
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35
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Liu B, Shi Q, Ma S, Feng N, Li J, Wang L, Wang X. Striatal 19S Rpt6 deficit is related to alpha-synuclein accumulation in MPTP-treated mice. Biochem Biophys Res Commun 2008; 376:277-82. [PMID: 18782562 DOI: 10.1016/j.bbrc.2008.08.142] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 08/23/2008] [Indexed: 12/31/2022]
Abstract
Striatal mitochondrial proteins were investigated using proteomics in the 1-methyl 4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. Four proteins, 19S proteasome ATPase Rpt6 (19S Rpt6), Lectin-related nature killer cell receptor LY 49S, Zinc finger A20 domain containing 1, and the sodium channel-associated protein 1 isoform 2, were significantly decreased while alpha-synuclein was increased in MPTP-treated mice. The altered levels of 19S Rpt6 and alpha-synuclein were further verified by Western blot. Experiments using small interfering RNA (siRNA) showed that alpha-synuclein was increased by 50% in cultured striatal neurons when 19S Rpt6 was knocked down. Taken together, our results imply that a deficiency in 19S Rpt6 may be partially related to the MPTP-induced increase in alpha-synuclein in the striatum.
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Affiliation(s)
- Bin Liu
- Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, 1# Xiannongtan Street, Xuanwu District, Beijing 100050, China
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36
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Cheung HH, Plenchette S, Kern CJ, Mahoney DJ, Korneluk RG. The RING domain of cIAP1 mediates the degradation of RING-bearing inhibitor of apoptosis proteins by distinct pathways. Mol Biol Cell 2008; 19:2729-40. [PMID: 18434593 DOI: 10.1091/mbc.e08-01-0107] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Inhibitor of Apoptosis proteins (IAPs) are key repressors of apoptosis. Several IAP proteins contain a RING domain that functions as an E3 ubiquitin ligase involved in the ubiquitin-proteasome pathway. Here we investigated the interplay of ubiquitin-proteasome pathway and RING-mediated IAP turnover. We found that the CARD-RING domain of cIAP1 (cIAP1-CR) is capable of down-regulating protein levels of RING-bearing IAPs such as cIAP1, cIAP2, XIAP, and Livin, while sparing NAIP and Survivin, which do not possess a RING domain. To determine whether polyubiquitination was required, we tested the ability of cIAP1-CR to degrade IAPs under conditions that impair ubiquitination modifications. Remarkably, although the ablation of E1 ubiquitin-activating enzyme prevented cIAP1-CR-mediated down-regulation of cIAP1 and cIAP2, there was no impact on degradation of XIAP and Livin. XIAP mutants that were not ubiquitinated in vivo were readily down-regulated by cIAP1-CR. Moreover, XIAP degradation in response to cisplatin and doxorubicin was largely prevented in cIAP1-silenced cells, despite cIAP2 up-regulation. The knockdown of cIAP1 and cIAP2 partially blunted Fas ligand-mediated down-regulation of XIAP and protected cells from cell death. Together, these results show that the E3 ligase RING domain of cIAP1 targets RING-bearing IAPs for proteasomal degradation by ubiquitin-dependent and -independent pathways.
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Affiliation(s)
- Herman H Cheung
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
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37
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Ju D, Wang X, Xu H, Xie Y. Genome-wide analysis identifies MYND-domain protein Mub1 as an essential factor for Rpn4 ubiquitylation. Mol Cell Biol 2008; 28:1404-12. [PMID: 18070918 PMCID: PMC2258742 DOI: 10.1128/mcb.01787-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 11/05/2007] [Accepted: 11/26/2007] [Indexed: 01/13/2023] Open
Abstract
The proteasome homeostasis in Saccharomyces cerevisiae is regulated by a negative feedback circuit in which the Rpn4 transcription factor upregulates the proteasome genes and is rapidly degraded by the proteasome. Previous work has identified Ubr2 and Rad6 as the cognate E3 and E2 enzymes for Rpn4 ubiquitylation. However, our recent attempts to ubiquitylate Rpn4 using purified Ubr2 and Rad6 proteins in a reconstitution system have been unsuccessful, suggesting that an additional factor is required for Rpn4 ubiquitylation. Here, we screened the entire collection of the single-gene-deletion yeast mutants generated by the Saccharomyces Genome Deletion Project and identified the mub1Delta mutant defective in ubiquitin-dependent degradation of Rpn4. An in vitro reconstitution ubiquitylation assay confirms that Mub1 is the missing factor for Rpn4 ubiquitylation. We further show that Mub1 directly interacts with Ubr2 and Rpn4. The MYND domain of Mub1 may play an important role in Rpn4 ubiquitylation. Interestingly, Mub1 itself is a short-lived protein and its degradation is dependent on the Ubr2/Rad6 ubiquitin ligase. Together, these data suggest that Mub1 and Ubr2 cooperate to transfer ubiquitin to Rpn4 from Rad6 and that Mub1 may switch from a partner to a substrate of the Ubr2/Rad6 ubiquitin ligase.
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Affiliation(s)
- Donghong Ju
- Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, 110 E. Warren Ave., Detroit, MI 48201, USA
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38
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Bronner C, Achour M, Arima Y, Chataigneau T, Saya H, Schini-Kerth VB. The UHRF family: Oncogenes that are drugable targets for cancer therapy in the near future? Pharmacol Ther 2007; 115:419-34. [PMID: 17658611 DOI: 10.1016/j.pharmthera.2007.06.003] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 06/07/2007] [Indexed: 12/21/2022]
Abstract
In this paper, we review the current literature about the UHRF family that in particular includes the UHRF1 and UHRF2 genes. Its members play a fundamental role in cell proliferation through different structural domains. These domains include a ubiquitin-like domain (NIRF_N), a plant homeodomain (PHD) domain, a SRA domain and a RING domain. The SRA domain has only been observed in this family probably conferring unique properties to it. The unique enzymatic activity so far identified in this family involves the RING finger that contains a ubiquitin E3 ligase activity toward, for instance, histones. The physiological roles played by the UHRF family are most likely exerted during embryogenic development and when proliferation is required in adults. Interestingly, UHRF members are putative oncogenes regulated by tumor suppressor genes, but they exert also a feedback control on these latter. Finally, we propose some new roles for this family, including regulation and/or inheritance of the epigenetic code. Alteration of these regulatory mechanisms, such as those occurring in cancer cells, may be involved in carcinogenesis. The reasons why the UHRF family could be an interesting target for developing anticancer drugs is also developed.
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Affiliation(s)
- Christian Bronner
- CNRS UMR 7175, Département de Pharmacologie et Pharmacochimie des Interactions Moléculaires et Cellulaires, Faculté de Pharmacie, 74 route du Rhin, BP 60024, 67401, Illkirch Cedex, France.
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39
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Dohmen RJ, Willers I, Marques AJ. Biting the hand that feeds: Rpn4-dependent feedback regulation of proteasome function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1599-604. [PMID: 17604855 DOI: 10.1016/j.bbamcr.2007.05.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 05/31/2007] [Indexed: 11/24/2022]
Abstract
The 26S proteasome of eukaryotic cells mediates ubiquitin-dependent as well as ubiquitin-independent degradation of proteins in many regulatory processes as well as in protein quality control. The proteasome itself is a dynamic complex with varying compositions and interaction partners. Studies in Saccharomyces cerevisiae have revealed that expression of proteasome subunit genes is coordinately controlled by the Rpn4 transcriptional activator. The cellular level of Rpn4 itself is subject to a complex regulation, which, aside of a transcriptional control of its gene, intriguingly involves ubiquitin-dependent as well as ubiquitin-independent control of its stability by the proteasome. A novel study by Ju et al. [D. Ju, H. Yu, X. Wang, Y. Xie, Ubiquitin-mediated degradation of Rpn4 is controlled by a phosphorylation-dependent ubiquitylation signal, Biochim. Biophys. Acta (in press), doi:10.1016/j.bbamcr.2007.04.012] now revealed another level of complexity by showing that phosphorylation of a specific serine residue in Rpn4 is required for its efficient targeting by the Ubr2 ubiquitin ligase.
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Affiliation(s)
- R Jürgen Dohmen
- Institute for Genetics, University of Cologne, Zülpicher Str. 47, D-50674 Cologne, Germany.
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40
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Seong KM, Baek JH, Yu MH, Kim J. Rpn13p and Rpn14p are involved in the recognition of ubiquitinated Gcn4p by the 26S proteasome. FEBS Lett 2007; 581:2567-73. [PMID: 17499717 DOI: 10.1016/j.febslet.2007.04.064] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 04/06/2007] [Accepted: 04/20/2007] [Indexed: 11/26/2022]
Abstract
The 26S proteasome, composed of the 20S core and 19S regulatory complexes, is important for the turnover of polyubiquitinated proteins. Each subunit of the complex plays a special role in proteolytic function, including substrate recruitment, deubiquitination, and structural contribution. To assess the function of some non-essential subunits in the 26S proteasome, we isolated the 26S proteasome from deletion strains of RPN13 and RPN14 using TAP affinity purification. The stability of Gcn4p and the accumulation of ubiquitinated Gcn4p were significantly increased, but the affinity in the recognition of proteasome was decreased. In addition, the subcomplexes of the isolated 26S proteasomes from deletion mutants were less stable than that of the wild type. Taken together, our findings indicate that Rpn13p and Rpn14p are involved in the efficient recognition of 26S proteasome for the proteolysis of ubiquitinated Gcn4p.
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Affiliation(s)
- Ki Moon Seong
- Laboratory of Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea
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41
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Ravid T, Hochstrasser M. Autoregulation of an E2 enzyme by ubiquitin-chain assembly on its catalytic residue. Nat Cell Biol 2007; 9:422-7. [PMID: 17310239 DOI: 10.1038/ncb1558] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Accepted: 02/05/2007] [Indexed: 11/09/2022]
Abstract
Cells have quality-control mechanisms to recognize non-native protein structures and either help the proteins fold or promote their degradation. Ubiquitin-conjugating enzymes (E2s) and ubiquitin ligases (E3s) work together to assemble polyubiquitin chains on misfolded or misassembled proteins, which are then degraded by the proteasome. Here, we find that Ubc7, a yeast E2, can itself undergo degradation when its levels exceed that of its binding partner Cue1, a transmembrane protein that tethers Ubc7 to the endoplasmic reticulum. Unassembled, and thus mislocalized, Ubc7 is targeted to the proteasome by Ufd4, a homologous to E6-AP C-terminus (HECT)-class E3. Ubc7 is autoubiquitinated by a novel mechanism wherein the catalytic cysteine, instead of a lysine residue, provides the polyubiquitin chain acceptor site, and this cysteine-linked chain functions as a degradation signal. The polyubiquitin chain can also be transferred to a lysine side chain, suggesting a mechanism for polyubiquitin chain assembly that precedes substrate modification.
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Affiliation(s)
- Tommer Ravid
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520, USA
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42
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Crosas B, Hanna J, Kirkpatrick DS, Zhang DP, Tone Y, Hathaway NA, Buecker C, Leggett DS, Schmidt M, King RW, Gygi SP, Finley D. Ubiquitin chains are remodeled at the proteasome by opposing ubiquitin ligase and deubiquitinating activities. Cell 2007; 127:1401-13. [PMID: 17190603 DOI: 10.1016/j.cell.2006.09.051] [Citation(s) in RCA: 244] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 08/25/2006] [Accepted: 09/29/2006] [Indexed: 11/21/2022]
Abstract
The ubiquitin ligase Hul5 was recently identified as a component of the proteasome, a multisubunit protease that degrades ubiquitin-protein conjugates. We report here a proteasome-dependent conjugating activity of Hul5 that endows proteasomes with the capacity to extend ubiquitin chains. hul5 mutants show reduced degradation of multiple proteasome substrates in vivo, suggesting that the polyubiquitin signal that targets substrates to the proteasome can be productively amplified at the proteasome. However, the products of Hul5 conjugation are subject to disassembly by a proteasome-bound deubiquitinating enzyme, Ubp6. A hul5 null mutation suppresses a ubp6 null mutation, suggesting that a balance of chain-extending and chain-trimming activities is required for proper proteasome function. As the association of Hul5 with proteasomes was found to be strongly stabilized by Ubp6, these enzymes may be situated in proximity to one another. We propose that through dynamic remodeling of ubiquitin chains, proteasomes actively regulate substrate commitment to degradation.
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Affiliation(s)
- Bernat Crosas
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Institut de Biologia Molecular de Barcelona, CSIC, Jordi Girona 18-26, Barcelona 08034, Spain
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43
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Ju D, Wang X, Xu H, Xie Y. The armadillo repeats of the Ufd4 ubiquitin ligase recognize ubiquitin-fusion proteins. FEBS Lett 2006; 581:265-70. [PMID: 17204268 DOI: 10.1016/j.febslet.2006.12.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 12/07/2006] [Accepted: 12/11/2006] [Indexed: 10/23/2022]
Abstract
Armadillo (ARM) repeats have been identified in proteins regulating cell junction assembly, nuclear transport and transcription activation. Recent studies showed that a large number of ubiquitin (Ub) ligases (or E3s) also contain ARM repeats. The function of the ARM repeats in these E3s, however, remains unknown. Here we report that the ARM repeats of Ufd4, the E3 component of the UFD (Ub fusion degradation) pathway, recognize the Ub degradation signal of the UFD substrates. Disruption of the ARM repeats abolishes the ubiquitylating activity of Ufd4. This study uncovers a new role of the ARM repeats in protein ubiquitylation.
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Affiliation(s)
- Donghong Ju
- Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, 110 E Warren Avenue, Detroit, MI 48201, USA
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44
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Gorbea C, Kaufmann AG, Pratt G, Rechsteiner M, Rogers SW. Multiple Forms of the 26S Proteasome-Associated Protein Ecm29 in the Mouse Brain. Isr J Chem 2006. [DOI: 10.1560/742p-et1j-8rlc-2jyv] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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45
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Cui M, Kim EB, Han M. Diverse chromatin remodeling genes antagonize the Rb-involved SynMuv pathways in C. elegans. PLoS Genet 2006; 2:e74. [PMID: 16710447 PMCID: PMC1463046 DOI: 10.1371/journal.pgen.0020074] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 03/29/2006] [Indexed: 01/05/2023] Open
Abstract
In Caenorhabditis elegans, vulval cell-fate specification involves the activities of multiple signal transduction and regulatory pathways that include a receptor tyrosine kinase/Ras/mitogen-activated protein kinase pathway and synthetic multivulva (SynMuv) pathways. Many genes in the SynMuv pathways encode transcription factors including the homologs of mammalian Rb, E2F, and components of the nucleosome-remodeling deacetylase complex. To further elucidate the functions of the SynMuv genes, we performed a genome-wide RNA interference (RNAi) screen to search for genes that antagonize the SynMuv gene activities. Among those that displayed a varying degree of suppression of the SynMuv phenotype, 32 genes are potentially involved in chromatin remodeling (called SynMuv suppressor genes herein). Genetic mutations of two representative genes (zfp-1 and mes-4) were used to further characterize their positive roles in vulval induction and relationships with Ras function. Our analysis revealed antagonistic roles of the SynMuv suppressor genes and the SynMuv B genes in germline-soma distinction, RNAi, somatic transgene silencing, and tissue specific expression of pgl-1 and the lag-2/Delta genes. The opposite roles of these SynMuv B and SynMuv suppressor genes on transcriptional regulation were confirmed in somatic transgene silencing. We also report the identifications of ten new genes in the RNAi pathway and six new genes in germline silencing. Among the ten new RNAi genes, three encode homologs of proteins involved in both protein degradation and chromatin remodeling. Our findings suggest that multiple chromatin remodeling complexes are involved in regulating the expression of specific genes that play critical roles in developmental decisions.
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Affiliation(s)
- Mingxue Cui
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - E. Bridget Kim
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Min Han
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
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Bloom J, Peschiaroli A, DeMartino G, Pagano M. Modification of Cul1 regulates its association with proteasomal subunits. Cell Div 2006; 1:5. [PMID: 16759355 PMCID: PMC1479330 DOI: 10.1186/1747-1028-1-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Accepted: 04/28/2006] [Indexed: 11/17/2022] Open
Abstract
Background Ubiquitylation targets proteins for degradation by the 26S proteasome. Some yeast and plant ubiquitin ligases, including the highly conserved SCF (Skp1/Cul1/F-box protein) complex, have been shown to associate with proteasomes. We sought to characterize interactions between SCF complexes and proteasomes in mammalian cells. Results We found that the binding of SCF complexes to proteasomes is conserved in higher eukaryotes. The Cul1 subunit associated with both sub-complexes of the proteasome, and high molecular weight forms of Cul1 bound to the 19S proteasome. Cul1 is ubiquitylated in vivo. Ubiquitylation of Cul1 promotes its binding to the S5a subunit of the 19S sub-complex without affecting Cul1 stability. Conclusion The association of ubiquitylating enzymes with proteasomes may be an additional means to target ubiquitylated substrates for degradation.
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Affiliation(s)
- Joanna Bloom
- Department of Pathology, New York University Cancer Institute and New York University School of Medicine, New York 10016, USA
- The Rockefeller University, New York 10021, USA
| | - Angelo Peschiaroli
- Department of Pathology, New York University Cancer Institute and New York University School of Medicine, New York 10016, USA
| | - George DeMartino
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA
| | - Michele Pagano
- Department of Pathology, New York University Cancer Institute and New York University School of Medicine, New York 10016, USA
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Ju D, Xie Y. A synthetic defect in protein degradation caused by loss of Ufd4 and Rad23. Biochem Biophys Res Commun 2006; 341:648-52. [PMID: 16430867 DOI: 10.1016/j.bbrc.2006.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 01/05/2006] [Indexed: 11/23/2022]
Abstract
The UFD (ubiquitin fusion degradation) pathway is responsible for multiubiquitination of the fusion proteins that bear a "non-removable" N-terminal ubiquitin moiety. Previous reports have shown that the UFD pathway is conserved from yeast to human. The essential elements of the UFD pathway have also been identified in Saccharomyces cerevisiae. These studies, however, are limited to use of engineered UFD substrates. The biological significance of the UFD pathway remains unknown. Here we demonstrate that Ufd4, the E3 component of the UFD pathway, is involved in controlling the degradation of Rad4, a nucleotide excision repair protein. Moreover, simultaneous loss of Ufd4 and Rad23 exhibits a synthetic inhibitory effect on Rad4 degradation, presenting the first example that a UBA/UBL-domain protein functionally overlaps with a ubiquitin ligase in determining the turnover rate of a protein substrate. The current work also provides a direction for further investigation of the physiological functions of the UFD pathway.
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Affiliation(s)
- Donghong Ju
- Barbara Ann Karmanos Cancer Institute, Department of Pathology, Wayne State University School of Medicine, 110 Warren Ave., Detroit, MI 48201, USA
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48
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Lee SJ, Choi D, Rhim H, Kang S. E3 ubiquitin ligase RNF2 interacts with the S6' proteasomal ATPase subunit and increases the ATP hydrolysis activity of S6'. Biochem J 2005; 389:457-63. [PMID: 15773819 PMCID: PMC1175123 DOI: 10.1042/bj20041982] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We reported previously that the human RNF2 (RING finger protein 2) protein is an E3 ubiquitin ligase that interacts with the human ubiquitin-conjugating enzyme Hip-2/hE2-25K. In the present study, we show that RNF2 interacts with S6' ATPase, a subunit of the proteasomal 19 S regulatory complex. S6' interacts with RNF2 through its N-terminal RING domain, and RNF2 interacts with S6' through its C-terminal region. Interestingly, the RNF2-S6' interaction increases the ATP hydrolysis activity of the S6' protein. Moreover, S6' ATPase activity is highly increased in the presence of ubiquitinated proteins. The present study suggests that the E3 ubiquitin ligase RNF2 might have a dual function: facilitating the ubiquitination of its target substrates and recruiting the substrates to the proteasome. Furthermore, ATP hydrolysis in the E3/proteasome complex might act as an important signal for the protein degradation pathway.
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Affiliation(s)
- Sun-Joo Lee
- *Graduate School of Biotechnology, Korea University, 1,5-ka Anam-dong, Sungbuk-ku, Seoul 136-701, South Korea
| | - Dongwon Choi
- *Graduate School of Biotechnology, Korea University, 1,5-ka Anam-dong, Sungbuk-ku, Seoul 136-701, South Korea
| | - Hyangshuk Rhim
- †Research Institute of Molecular Genetics, College of Medicine, Catholic University of Korea, Seoul 137-701, South Korea
| | - Seongman Kang
- *Graduate School of Biotechnology, Korea University, 1,5-ka Anam-dong, Sungbuk-ku, Seoul 136-701, South Korea
- To whom correspondence should be addressed (email )
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49
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Schmidt M, Hanna J, Elsasser S, Finley D. Proteasome-associated proteins: regulation of a proteolytic machine. Biol Chem 2005; 386:725-37. [PMID: 16201867 DOI: 10.1515/bc.2005.085] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The proteasome is a compartmentalized, ATP-dependent protease composed of more than 30 subunits that recognizes and degrades polyubiquitinated substrates. Despite its physiological importance, many aspects of the proteasome's structural organization and regulation remain poorly understood. In addition to the proteins that form the proteasome holocomplex, there is increasing evidence that proteasomal function is affected by a wide variety of associating proteins. A group of ubiquitin-binding proteins assist in delivery of substrates to the proteasome, whereas proteasome-associated ubiquitin ligases and deubiquitinating enzymes may alter the dynamics of ubiquitin chains already associated with the proteasome. Some proteins appear to influence the overall stability of the complex, and still others have the capacity to activate or inhibit the hydrolytic activity of the core particle. The increasing number of interacting proteins identified suggests that proteasomes, as they exist in the cell, are larger and more diverse in composition than previously assumed. Thus, the study of proteasome-associated proteins will lead to new perspectives on the dynamics of this uniquely complex proteolytic machine.
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Affiliation(s)
- Marion Schmidt
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
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50
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Löscher M, Fortschegger K, Ritter G, Wostry M, Voglauer R, Schmid J, Watters S, Rivett A, Ajuh P, Lamond A, Katinger H, Grillari J. Interaction of U-box E3 ligase SNEV with PSMB4, the beta7 subunit of the 20 S proteasome. Biochem J 2005; 388:593-603. [PMID: 15660529 PMCID: PMC1138967 DOI: 10.1042/bj20041517] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recognition of specific substrates for degradation by the ubiquitin-proteasome pathway is ensured by a cascade of ubiquitin transferases E1, E2 and E3. The mechanism by which the target proteins are transported to the proteasome is not clear, but two yeast E3s and one mammalian E3 ligase seem to be involved in the delivery of targets to the proteasome, by escorting them and by binding to the 19 S regulatory particle of the proteasome. In the present study, we show that SNEV (senescence evasion factor), a protein with in vitro E3 ligase activity, which is also involved in DNA repair and splicing, associates with the proteasome by directly binding to the beta7 subunit of the 20 S proteasome. Upon inhibition of proteasome activity, SNEV does not accumulate within the cells although its co-localization with the proteasome increases significantly. Since immunofluorescence microscopy also shows increased co-localization of SNEV with ubiquitin after proteasome inhibition, without SNEV being ubiquitinated by itself, we suggest that SNEV shows E3 ligase activity not only in vitro but also in vivo and escorts its substrate to the proteasome. Since the yeast homologue of SNEV, Prp19, also interacts with the yeast beta7 subunit of the proteasome, this mechanism seems to be conserved during evolution. Therefore these results support the hypothesis that E3 ligases might generally be involved in substrate transport to the proteasome. Additionally, our results provide the first evidence for a physical link between components of the ubiquitin-proteasome system and the spliceosome.
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Affiliation(s)
- Marlies Löscher
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Klaus Fortschegger
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Gustav Ritter
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Martina Wostry
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Regina Voglauer
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Johannes A. Schmid
- †Department of Vascular Biology and Thrombosis Research, University of Vienna, Brunnerstrasse 59, A-1235 Vienna, Austria
| | - Steven Watters
- ‡The Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, U.K
| | - A. Jennifer Rivett
- ‡The Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, U.K
| | - Paul Ajuh
- §Division of Gene Regulation and Expression, Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Angus I. Lamond
- §Division of Gene Regulation and Expression, Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Hermann Katinger
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Johannes Grillari
- *Institute of Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
- ∥BMT Biomolecular Therapeutics, Brunnerstrasse 59, Vienna, Austria
- To whom correspondence should be addressed, at Muthgasse 18, A-1190, Vienna, Austria (email )
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