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Kawarasaki T, Nakatsukasa K. Metabolomics analysis of an AAA-ATPase Cdc48-deficient yeast strain. Heliyon 2023; 9:e13219. [PMID: 36761826 PMCID: PMC9905943 DOI: 10.1016/j.heliyon.2023.e13219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/13/2023] [Accepted: 01/20/2023] [Indexed: 01/25/2023] Open
Abstract
The ubiquitin-specific chaperone AAA-ATPase Cdc48 and its orthologs p97/valosin-containing protein (VCP) in mammals play crucial roles in regulating numerous intracellular pathways via segregase activity, which separates polyubiquitinated targets from membranes or binding partners. Interestingly, high-throughput experiments show that a vast number of metabolic enzymes are modified with ubiquitin. Therefore, Cdc48 may regulate metabolic pathways, for example by acting on the polyubiquitin chains of metabolic enzymes; however, the role of Cdc48 in metabolic regulation remains largely unknown. To begin to analyze the role of Cdc48 in metabolic regulation in yeast, we performed a metabolomics analysis of temperature-sensitive cdc48-3 mutant cells. We found that the amount of metabolites in the glycolytic pathway was altered. Moreover, the pool of nucleotides, as well as the levels of metabolites involved in the tricarboxylic acid cycle and oxidative phosphorylation, increased, whereas the pool of amino acids decreased. These results suggest the involvement of Cdc48 in metabolic regulation in yeast. In addition, because of the roles of p97/VCP in regulating multiple cellular pathways, its inhibition is being considered as a promising anticancer drug target. We propose that the metabolomics study of Cdc48-deficient yeast will be useful as a complement to p97/VCP-related pathological and therapeutic studies.
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Structural and Functional Insights into GID/CTLH E3 Ligase Complexes. Int J Mol Sci 2022; 23:ijms23115863. [PMID: 35682545 PMCID: PMC9180843 DOI: 10.3390/ijms23115863] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 11/29/2022] Open
Abstract
Multi-subunit E3 ligases facilitate ubiquitin transfer by coordinating various substrate receptor subunits with a single catalytic center. Small molecules inducing targeted protein degradation have exploited such complexes, proving successful as therapeutics against previously undruggable targets. The C-terminal to LisH (CTLH) complex, also called the glucose-induced degradation deficient (GID) complex, is a multi-subunit E3 ligase complex highly conserved from Saccharomyces cerevisiae to humans, with roles in fundamental pathways controlling homeostasis and development in several species. However, we are only beginning to understand its mechanistic basis. Here, we review the literature of the CTLH complex from all organisms and place previous findings on individual subunits into context with recent breakthroughs on its structure and function.
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Screening and Validation of Significant Genes with Poor Prognosis in Pathologic Stage-I Lung Adenocarcinoma. JOURNAL OF ONCOLOGY 2022; 2022:3794021. [PMID: 35444699 PMCID: PMC9015852 DOI: 10.1155/2022/3794021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/05/2022] [Indexed: 11/17/2022]
Abstract
Background Although more pathologic stage-I lung adenocarcinoma (LUAD) was diagnosed recently, some relapsed or distantly metastasized shortly after radical resection. The study aimed to identify biomarkers predicting prognosis in the pathologic stage-I LUAD and improve the understanding of the mechanisms involved in tumorigenesis. Methods We obtained the expression profiling data for non-small cell lung cancer (NSCLC) patients from the NCBI-GEO database. Differentially expressed genes (DEGs) between early-stage NSCLC and normal lung tissue were determined. After function enrichment analyses on DEGs, the protein-protein interaction (PPI) network was built and analyzed with the Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape. Overall survival (OS) and mRNA levels of genes were performed with Kaplan–Meier analysis and Gene Expression Profiling Interactive Analysis (GEPIA). qPCR and western blot analysis of hub genes in stage-I LUAD patients validated the significant genes with poor prognosis. Results A total of 172 DEGs were identified, which were mainly enriched in terms related to management of extracellular matrix (ECM), receptor signaling pathway, cell adhesion, activity of endopeptidase, and receptor. The PPI network identified 11 upregulated hub genes that were significantly associated with OS in NSCLC and highly expressed in NSCLC tissues compared with normal tissues by GEPIA. Elevated expression of ANLN, EXO1, KIAA0101, RRM2, TOP2A, and UBE2T were identified as potential risk factors in pathologic stage-I LUAD. Except for ANLN and KIAA0101, the hub genes mRNA levels were higher in tumors compared with adjacent non-cancerous samples in the qPCR analysis. The hub genes protein levels were also overexpressed in tumors. In vitro experiments showed that knockdown of UBE2T in LUAD cell lines could inhibit cell proliferation and cycle progression. Conclusions The DEGs can probably be used as potential predictors for stage-I LUAD worse prognosis and UBE2T may be a potential tumor promoter and target for treatment.
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Chrustowicz J, Sherpa D, Teyra J, Loke MS, Popowicz GM, Basquin J, Sattler M, Prabu JR, Sidhu SS, Schulman BA. Multifaceted N-Degron Recognition and Ubiquitylation by GID/CTLH E3 Ligases. J Mol Biol 2021; 434:167347. [PMID: 34767800 DOI: 10.1016/j.jmb.2021.167347] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/22/2022]
Abstract
N-degron E3 ubiquitin ligases recognize specific residues at the N-termini of substrates. Although molecular details of N-degron recognition are known for several E3 ligases, the range of N-terminal motifs that can bind a given E3 substrate binding domain remains unclear. Here, we discovered capacity of Gid4 and Gid10 substrate receptor subunits of yeast "GID"/human "CTLH" multiprotein E3 ligases to tightly bind a wide range of N-terminal residues whose recognition is determined in part by the downstream sequence context. Screening of phage displaying peptide libraries with exposed N-termini identified novel consensus motifs with non-Pro N-terminal residues binding Gid4 or Gid10 with high affinity. Structural data reveal that conformations of flexible loops in Gid4 and Gid10 complement sequences and folds of interacting peptides. Together with analysis of endogenous substrate degrons, the data show that degron identity, substrate domains harboring targeted lysines, and varying E3 ligase higher-order assemblies combinatorially determine efficiency of ubiquitylation and degradation.
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Affiliation(s)
- Jakub Chrustowicz
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. https://twitter.com/chrustowicz_j
| | - Dawafuti Sherpa
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. https://twitter.com/dawafutisherpa
| | - Joan Teyra
- The Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Mun Siong Loke
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Grzegorz M Popowicz
- Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Germany
| | - Jerome Basquin
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Michael Sattler
- Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Germany
| | - J Rajan Prabu
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. https://twitter.com/rajanprabu
| | - Sachdev S Sidhu
- The Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
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5
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Sherpa D, Chrustowicz J, Qiao S, Langlois CR, Hehl LA, Gottemukkala KV, Hansen FM, Karayel O, von Gronau S, Prabu JR, Mann M, Alpi AF, Schulman BA. GID E3 ligase supramolecular chelate assembly configures multipronged ubiquitin targeting of an oligomeric metabolic enzyme. Mol Cell 2021; 81:2445-2459.e13. [PMID: 33905682 PMCID: PMC8189437 DOI: 10.1016/j.molcel.2021.03.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 02/17/2021] [Accepted: 03/17/2021] [Indexed: 12/31/2022]
Abstract
How are E3 ubiquitin ligases configured to match substrate quaternary structures? Here, by studying the yeast GID complex (mutation of which causes deficiency in glucose-induced degradation of gluconeogenic enzymes), we discover supramolecular chelate assembly as an E3 ligase strategy for targeting an oligomeric substrate. Cryoelectron microscopy (cryo-EM) structures show that, to bind the tetrameric substrate fructose-1,6-bisphosphatase (Fbp1), two minimally functional GID E3s assemble into the 20-protein Chelator-GIDSR4, which resembles an organometallic supramolecular chelate. The Chelator-GIDSR4 assembly avidly binds multiple Fbp1 degrons so that multiple Fbp1 protomers are simultaneously ubiquitylated at lysines near the allosteric and substrate binding sites. Importantly, key structural and biochemical features, including capacity for supramolecular assembly, are preserved in the human ortholog, the CTLH E3. Based on our integrative structural, biochemical, and cell biological data, we propose that higher-order E3 ligase assembly generally enables multipronged targeting, capable of simultaneously incapacitating multiple protomers and functionalities of oligomeric substrates.
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Affiliation(s)
- Dawafuti Sherpa
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Jakub Chrustowicz
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Shuai Qiao
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Christine R Langlois
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Laura A Hehl
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Karthik Varma Gottemukkala
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Fynn M Hansen
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Ozge Karayel
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Susanne von Gronau
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - J Rajan Prabu
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Arno F Alpi
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany.
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Scazzari M, Amm I, Wolf DH. Quality control of a cytoplasmic protein complex: chaperone motors and the ubiquitin-proteasome system govern the fate of orphan fatty acid synthase subunit Fas2 of yeast. J Biol Chem 2015; 290:4677-4687. [PMID: 25564609 PMCID: PMC4335207 DOI: 10.1074/jbc.m114.596064] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 12/10/2014] [Indexed: 11/06/2022] Open
Abstract
For the assembly of protein complexes in the cell, the presence of stoichiometric amounts of the respective protein subunits is of utmost importance. A surplus of any of the subunits may trigger unspecific and harmful protein interactions and has to be avoided. A stoichiometric amount of subunits must finally be reached via transcriptional, translational, and/or post-translational regulation. Synthesis of saturated 16 and 18 carbon fatty acids is carried out by fatty acid synthase: in yeast Saccharomyces cerevisiae, a 2.6-MDa molecular mass assembly containing six protomers each of two different subunits, Fas1 (β) and Fas2 (α). The (α)6(β)6 complex carries six copies of all eight enzymatic activities required for fatty acid synthesis. The FAS1 and FAS2 genes in yeast are unlinked and map on two different chromosomes. Here we study the fate of the α-subunit of the complex, Fas2, when its partner, the β-subunit Fas1, is absent. Individual subunits of fatty acid synthase are proteolytically degraded when the respective partner is missing. Elimination of Fas2 is achieved by the proteasome. Here we show that a ubiquitin transfer machinery is required for Fas2 elimination. The major ubiquitin ligase targeting the superfluous Fas2 subunit to the proteasome is Ubr1. The ubiquitin-conjugating enzymes Ubc2 and Ubc4 assist the degradation process. The AAA-ATPase Cdc48 and the Hsp70 chaperone Ssa1 are crucially involved in the elimination of Fas2.
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Affiliation(s)
- Mario Scazzari
- From the Institut für Biochemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Ingo Amm
- From the Institut für Biochemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Dieter H Wolf
- From the Institut für Biochemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
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Chan NC, den Besten W, Sweredoski MJ, Hess S, Deshaies RJ, Chan DC. Degradation of the deubiquitinating enzyme USP33 is mediated by p97 and the ubiquitin ligase HERC2. J Biol Chem 2014; 289:19789-98. [PMID: 24855649 DOI: 10.1074/jbc.m114.569392] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Because the deubiquitinating enzyme USP33 is involved in several important cellular processes (β-adrenergic receptor recycling, centrosome amplification, RalB signaling, and cancer cell migration), its levels must be carefully regulated. Using quantitative mass spectrometry, we found that the intracellular level of USP33 is highly sensitive to the activity of p97. Knockdown or chemical inhibition of p97 causes robust accumulation of USP33 due to inhibition of its degradation. The p97 adaptor complex involved in this function is the Ufd1-Npl4 heterodimer. Furthermore, we identified HERC2, a HECT domain-containing E3 ligase, as being responsible for polyubiquitination of USP33. Inhibition of p97 causes accumulation of polyubiquitinated USP33, suggesting that p97 is required for postubiquitination processing. Thus, our study has identified several key molecules that control USP33 degradation within the ubiquitin-proteasome system.
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Affiliation(s)
- Nickie C Chan
- From the Division of Biology and Biological Engineering, the Howard Hughes Medical Institute, and
| | | | - Michael J Sweredoski
- From the Division of Biology and Biological Engineering, the Proteome Exploration Laboratory/Beckman Institute, California Institute of Technology, Pasadena, California 91125
| | - Sonja Hess
- From the Division of Biology and Biological Engineering, the Proteome Exploration Laboratory/Beckman Institute, California Institute of Technology, Pasadena, California 91125
| | - Raymond J Deshaies
- From the Division of Biology and Biological Engineering, the Howard Hughes Medical Institute, and
| | - David C Chan
- From the Division of Biology and Biological Engineering, the Howard Hughes Medical Institute, and
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Previously unknown role for the ubiquitin ligase Ubr1 in endoplasmic reticulum-associated protein degradation. Proc Natl Acad Sci U S A 2013; 110:15271-6. [PMID: 23988329 DOI: 10.1073/pnas.1304928110] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Quality control and degradation of misfolded proteins are essential processes of all cells. The endoplasmic reticulum (ER) is the entry site of proteins into the secretory pathway in which protein folding occurs and terminally misfolded proteins are recognized and retrotranslocated across the ER membrane into the cytosol. Here, proteins undergo polyubiquitination by one of the membrane-embedded ubiquitin ligases, in yeast Hrd1/Der3 (HMG-CoA reductase degradation/degradation of the ER) and Doa10 (degradation of alpha), and are degraded by the proteasome. In this study, we identify cytosolic Ubr1 (E3 ubiquitin ligase, N-recognin) as an additional ubiquitin ligase that can participate in ER-associated protein degradation (ERAD) in yeast. We show that two polytopic ERAD substrates, mutated transporter of the mating type a pheromone, Ste6* (sterile), and cystic fibrosis transmembrane conductance regulator, undergo Ubr1-dependent degradation in the presence and absence of the canonical ER ubiquitin ligases. Whereas in the case of Ste6* Ubr1 is specifically required under stress conditions such as heat or ethanol or in the absence of the canonical ER ligases, efficient degradation of human cystic fibrosis transmembrane conductance regulator requires function of Ubr1 already in wild-type cells under standard growth conditions. Together with the Hsp70 (heat shock protein) chaperone Ssa1 (stress-seventy subfamily A) and the AAA-type ATPase Cdc48 (cell division cycle), Ubr1 directs the substrate to proteasomal degradation. These data unravel another layer of complexity in ERAD.
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Kolawa N, Sweredoski MJ, Graham RLJ, Oania R, Hess S, Deshaies RJ. Perturbations to the ubiquitin conjugate proteome in yeast δubx mutants identify Ubx2 as a regulator of membrane lipid composition. Mol Cell Proteomics 2013; 12:2791-803. [PMID: 23793018 PMCID: PMC3790291 DOI: 10.1074/mcp.m113.030163] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast Cdc48 (p97/VCP in human cells) is a hexameric AAA ATPase that is thought to use ATP hydrolysis to power the segregation of ubiquitin-conjugated proteins from tightly bound partners. Current models posit that Cdc48 is linked to its substrates through adaptor proteins, including a family of seven proteins (13 in human) that contain a Cdc48-binding UBX domain. However, few substrates for specific UBX proteins are known, and hence the generality of this hypothesis remains untested. Here, we use mass spectrometry to identify ubiquitin conjugates that accumulate in cdc48 and ubx mutants. Different ubx mutants exhibit unique patterns of conjugate accumulation that point to functional specialization of individual Ubx proteins. To validate our findings, we examined in detail the endoplasmic reticulum-bound transcription factor Spt23, which we identified as a putative Ubx2 substrate. Mutant ubx2Δ cells are deficient in both cleaving the ubiquitinated 120 kDa precursor of Spt23 to form active p90 and in localizing p90 to the nucleus, resulting in reduced expression of the target gene OLE1, which encodes fatty acid desaturase. Our findings provide a resource for future investigations on Cdc48, illustrate the utility of proteomics to identify ligands for specific ubiquitin receptor pathways, and uncover Ubx2 as a key player in the regulation of membrane lipid biosynthesis.
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Abstract
The chaperone-related, ubiquitin-selective AAA (ATPase associated with a variety of cellular activities) protein Cdc48 (also known as TER94, p97 and VCP) is a key regulator of intracellular proteolysis in eukaryotes. It uses the energy derived from ATP hydrolysis to segregate ubiquitylated proteins from stable assemblies with proteins, membranes and chromatin. Originally characterized as essential factor in proteasomal degradation pathways, Cdc48 was recently found to control lysosomal protein degradation as well. Moreover, impaired lysosomal proteolysis due to mutational inactivation of Cdc48 causes protein aggregation diseases in humans. This review introduces the major systems of intracellular proteolysis in eukaryotes and the role of protein ubiquitylation. It then discusses in detail structure, mechanism and cellular functions of Cdc48 with an emphasis on protein degradation pathways in yeast.
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Affiliation(s)
- Alexander Buchberger
- Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, 97074, Würzburg, Germany,
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11
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Braun B, Pfirrmann T, Menssen R, Hofmann K, Scheel H, Wolf DH. Gid9, a second RING finger protein contributes to the ubiquitin ligase activity of the Gid complex required for catabolite degradation. FEBS Lett 2011; 585:3856-61. [PMID: 22044534 DOI: 10.1016/j.febslet.2011.10.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/20/2011] [Accepted: 10/23/2011] [Indexed: 10/15/2022]
Abstract
The two major antagonistic pathways of carbon metabolism in cells, glycolysis and gluconeogenesis, are tightly regulated. In the eukaryotic model organism Saccharomyces cerevisiae the switch from gluconeogenesis to glycolysis is brought about by proteasomal degradation of the gluconeogenic enzyme fructose-1,6-bisphosphatase. The ubiquitin ligase responsible for polyubiquitylation of fructose-1,6-bisphosphatase is the Gid complex. This complex consists of seven subunits of which subunit Gid2/Rmd5 contains a RING finger domain providing E3 ligase activity. Here we identify an additional subunit containing a degenerated RING finger, Gid9/Fyv10. This subunit binds to Gid2/Rmd5. A mutation in the degenerated RING finger of Gid9/Fyv10 abolishes polyubiquitylation and degradation of three enzymes specific for gluconeogenesis.
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Affiliation(s)
- Bernhard Braun
- Institut für Biochemie, Universität Stuttgart, Stuttgart, Germany
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12
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Cdc48: a power machine in protein degradation. Trends Biochem Sci 2011; 36:515-23. [PMID: 21741246 DOI: 10.1016/j.tibs.2011.06.001] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 05/27/2011] [Accepted: 06/01/2011] [Indexed: 11/24/2022]
Abstract
Cdc48 is an essential, highly prominent ATP driven machine in eukaryotic cells. Physiological function of Cdc48 has been found in a multitude of cellular processes, for instance cell cycle progression, homotypic membrane fusion, chromatin remodeling, transcriptional and metabolic regulation, and many others. The molecular function of Cdc48 is arguably best understood in endoplasmic reticulum-associated protein degradation by the ubiquitin proteasome system. In this review, we summarize the general characteristics of Cdc48/p97 and the most recent results on the molecular function of Cdc48 in some of the above processes, which were found to finally end in proteolysis-connected pathways, either involving the proteasome or autophagocytosis-mediated lysosomal degradation.
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Verma R, Oania R, Fang R, Smith GT, Deshaies RJ. Cdc48/p97 mediates UV-dependent turnover of RNA Pol II. Mol Cell 2011; 41:82-92. [PMID: 21211725 PMCID: PMC3063307 DOI: 10.1016/j.molcel.2010.12.017] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 10/09/2010] [Accepted: 12/10/2010] [Indexed: 12/13/2022]
Abstract
Cdc48/p97 is an essential ATPase whose role in targeting substrates to the ubiquitin-proteasome system (UPS) remains unclear. Existing models posit that Cdc48 acts upstream of UPS receptors. To address this hypothesis, we examined the association of ubiquitin (Ub) conjugates with 26S proteasomes. Unexpectedly, proteasomes isolated from cdc48 mutants contain high levels of Ub conjugates, and mass spectrometry identified numerous nonproteasomal proteins, including Rpb1, the largest subunit of RNA Pol II. UV-induced turnover of Rpb1 depends upon Cdc48-Ufd1-Npl4, Ubx4, and the uncharacterized adaptor Ubx5. Ubiquitinated Rpb1, proteasomes, and Cdc48 accumulate on chromatin in UV-treated wild-type cells, and the former two accumulate to higher levels in mutant cells, suggesting that degradation of Rpb1 is facilitated by Cdc48 at sites of stalled transcription. These data reveal an intimate coupling of function between proteasomes and Cdc48 that we suggest is necessary to sustain processive degradation of unstable subunits of some macromolecular protein complexes.
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Affiliation(s)
- Rati Verma
- California Institute of Technology, Pasadena, CA 91125, USA.
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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15
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Juretschke J, Menssen R, Sickmann A, Wolf DH. The Hsp70 chaperone Ssa1 is essential for catabolite induced degradation of the gluconeogenic enzyme fructose-1,6-bisphosphatase. Biochem Biophys Res Commun 2010; 397:447-52. [DOI: 10.1016/j.bbrc.2010.05.123] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 05/23/2010] [Indexed: 01/17/2023]
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