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Pluska L, Jarosch E, Zauber H, Kniss A, Waltho A, Bagola K, von Delbrück M, Löhr F, Schulman BA, Selbach M, Dötsch V, Sommer T. The UBA domain of conjugating enzyme Ubc1/Ube2K facilitates assembly of K48/K63-branched ubiquitin chains. EMBO J 2021; 40:e106094. [PMID: 33576509 PMCID: PMC7957398 DOI: 10.15252/embj.2020106094] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 12/22/2020] [Accepted: 01/05/2021] [Indexed: 12/23/2022] Open
Abstract
The assembly of a specific polymeric ubiquitin chain on a target protein is a key event in the regulation of numerous cellular processes. Yet, the mechanisms that govern the selective synthesis of particular polyubiquitin signals remain enigmatic. The homologous ubiquitin-conjugating (E2) enzymes Ubc1 (budding yeast) and Ube2K (mammals) exclusively generate polyubiquitin linked through lysine 48 (K48). Uniquely among E2 enzymes, Ubc1 and Ube2K harbor a ubiquitin-binding UBA domain with unknown function. We found that this UBA domain preferentially interacts with ubiquitin chains linked through lysine 63 (K63). Based on structural modeling, in vitro ubiquitination experiments, and NMR studies, we propose that the UBA domain aligns Ubc1 with K63-linked polyubiquitin and facilitates the selective assembly of K48/K63-branched ubiquitin conjugates. Genetic and proteomics experiments link the activity of the UBA domain, and hence the formation of this unusual ubiquitin chain topology, to the maintenance of cellular proteostasis.
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Affiliation(s)
- Lukas Pluska
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
| | - Ernst Jarosch
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
| | - Henrik Zauber
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
| | - Andreas Kniss
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic ResonanceGoethe UniversityFrankfurt am MainGermany
| | - Anita Waltho
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
| | - Katrin Bagola
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
| | | | - Frank Löhr
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic ResonanceGoethe UniversityFrankfurt am MainGermany
| | - Brenda A Schulman
- Department of Molecular Machines and SignalingMax Planck Institute of BiochemistryMartinsriedGermany
| | - Matthias Selbach
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
- Charité – Universitätsmedizin BerlinBerlinGermany
| | - Volker Dötsch
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic ResonanceGoethe UniversityFrankfurt am MainGermany
| | - Thomas Sommer
- Max‐Delbrück‐Center for Molecular Medicine in the Helmholtz AssociationBerlin‐BuchGermany
- Institute for BiologyHumboldt‐Universität zu BerlinBerlinGermany
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Wang C, Long W, Peng C, Hu L, Zhang Q, Wu A, Zhang X, Duan X, Wong CCL, Tanaka Y, Xia Z. HTLV-1 Tax Functions as a Ubiquitin E3 Ligase for Direct IKK Activation via Synthesis of Mixed-Linkage Polyubiquitin Chains. PLoS Pathog 2016; 12:e1005584. [PMID: 27082114 PMCID: PMC4833305 DOI: 10.1371/journal.ppat.1005584] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/29/2016] [Indexed: 11/29/2022] Open
Abstract
The HTLV-1 oncoprotein Tax plays a key role in CD4+ T cell transformation by promoting cell proliferation and survival, mainly through permanent activation of the NK-κB pathway and induction of many NF-κB target genes. Elucidating the underlying molecular mechanism is therefore critical in understanding HTLV-1-mediated transformation. Current studies have suggested multiple but controversial mechanisms regarding Tax-induced IKK activation mainly due to blending of primary Tax-induced IKK activation events and secondary IKK activation events induced by cytokines secreted by the primary Tax-induced IKK-NF-κB activation events. We reconstituted Tax-stimulated IKK activation in a cell-free system to dissect the essential cellular components for primary IKK activation by Tax and studied the underlying biochemical mechanism. We found that Tax is a putative E3 ubiquitin ligase, which, together with UbcH2, UhcH5c, or UbcH7, catalyzes the assembly of free mixed-linkage polyubiquitin chains. These free mixed-linkage polyubiquitin chains are then responsible for direct IKK activation by binding to the NEMO subunit of IKK. Our studies revealed the biochemical function of Tax in the process of IKK activation, which utilizes the minimal cellular ubiquitination components for NF-κB activation. Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM), a distinct neurological disorder with inflammatory symptoms and incomplete paralysis of the limbs, and adult T-cell leukemia/lymphoma (ATL), a highly aggressive malignant proliferation of CD4+ T lymphocytes. Both TSP/HAM and ATL are mainly driven by the activation of IκB kinase (IKK)-NF-κB stimulated by HTLV-1 oncoprotein Tax. The molecular mechanism by which Tax activates IKK remains unclear. Here, we found that Tax is an E3 ubiquitin ligase, which, together with its cognate ubiquitin-conjugating enzymes (E2s) UbcH2, UhcH5c, or UbcH7, catalyzes the assembly of unanchored free mixed-linkage polyubiquitin chains. The polyubiquitin chains can activate IKK complex directly by binding to the NEMO subunit. Our studies uncovered the essential cellular factors hijacked by HTLV-1 for infection and pathogenesis, as well as the biochemical function and the underlying mechanism of Tax in the process of IKK activation. Our work might shed light on potential development of therapeutics for TSP/HAM and ATL.
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Affiliation(s)
- Chong Wang
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wenying Long
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chao Peng
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Shanghai Science Research Center, Chinese Academy of Sciences, Shanghai, China
| | - Lin Hu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qiong Zhang
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ailing Wu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaoqing Zhang
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaotao Duan
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Catherine C. L. Wong
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Shanghai Science Research Center, Chinese Academy of Sciences, Shanghai, China
| | - Yuetsu Tanaka
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, Nishihara-cho, Okinawa, Japan
| | - Zongping Xia
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, China
- * E-mail:
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Rajsbaum R, Versteeg GA, Schmid S, Maestre AM, Belicha-Villanueva A, Martínez-Romero C, Patel JR, Morrison J, Pisanelli G, Miorin L, Laurent-Rolle M, Moulton HM, Stein DA, Fernandez-Sesma A, tenOever BR, García-Sastre A. Unanchored K48-linked polyubiquitin synthesized by the E3-ubiquitin ligase TRIM6 stimulates the interferon-IKKε kinase-mediated antiviral response. Immunity 2014; 40:880-95. [PMID: 24882218 DOI: 10.1016/j.immuni.2014.04.018] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 04/07/2014] [Indexed: 12/18/2022]
Abstract
Type I interferons (IFN-I) are essential antiviral cytokines produced upon microbial infection. IFN-I elicits this activity through the upregulation of hundreds of IFN-I-stimulated genes (ISGs). The full breadth of ISG induction demands activation of a number of cellular factors including the IκB kinase epsilon (IKKε). However, the mechanism of IKKε activation upon IFN receptor signaling has remained elusive. Here we show that TRIM6, a member of the E3-ubiquitin ligase tripartite motif (TRIM) family of proteins, interacted with IKKε and promoted induction of IKKε-dependent ISGs. TRIM6 and the E2-ubiquitin conjugase UbE2K cooperated in the synthesis of unanchored K48-linked polyubiquitin chains, which activated IKKε for subsequent STAT1 phosphorylation. Our work attributes a previously unrecognized activating role of K48-linked unanchored polyubiquitin chains in kinase activation and identifies the UbE2K-TRIM6-ubiquitin axis as critical for IFN signaling and antiviral response.
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Affiliation(s)
- Ricardo Rajsbaum
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Gijs A Versteeg
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9/4, 1030 Vienna, Austria
| | - Sonja Schmid
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Ana M Maestre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Alan Belicha-Villanueva
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Carles Martínez-Romero
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jenish R Patel
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Juliet Morrison
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Giuseppe Pisanelli
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Via Federico Delpino 1, 80137 Naples, Italy
| | - Lisa Miorin
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Maudry Laurent-Rolle
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Hong M Moulton
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - David A Stein
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Ana Fernandez-Sesma
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Benjamin R tenOever
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA.
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Stieglitz B, Morris-Davies AC, Koliopoulos MG, Christodoulou E, Rittinger K. LUBAC synthesizes linear ubiquitin chains via a thioester intermediate. EMBO Rep 2012; 13:840-6. [PMID: 22791023 PMCID: PMC3432797 DOI: 10.1038/embor.2012.105] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 06/21/2012] [Accepted: 06/22/2012] [Indexed: 01/31/2023] Open
Abstract
The linear ubiquitin chain assembly complex (LUBAC) is a RING E3 ligase that regulates immune and inflammatory signalling pathways. Unlike classical RING E3 ligases, LUBAC determines the type of ubiquitin chain being formed, an activity normally associated with the E2 enzyme. We show that the RING-in-between-RING (RBR)-containing region of HOIP--the catalytic subunit of LUBAC--is sufficient to generate linear ubiquitin chains. However, this activity is inhibited by the N-terminal portion of the molecule, an inhibition that is released upon complex formation with HOIL-1L or SHARPIN. Furthermore, we demonstrate that HOIP transfers ubiquitin to the substrate through a thioester intermediate formed by a conserved cysteine in the RING2 domain, supporting the notion that RBR ligases act as RING/HECT hybrids.
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Affiliation(s)
- Benjamin Stieglitz
- Division of Molecular Structure, MRC-National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK
| | - Aylin C Morris-Davies
- Division of Molecular Structure, MRC-National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK
| | - Marios G Koliopoulos
- Division of Molecular Structure, MRC-National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK
| | - Evangelos Christodoulou
- Division of Molecular Structure, MRC-National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK
| | - Katrin Rittinger
- Division of Molecular Structure, MRC-National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK
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Madiraju C, Welsh K, Cuddy MP, Godoi PH, Pass I, Ngo T, Vasile S, Sergienko EA, Diaz P, Matsuzawa SI, Reed JC. TR-FRET-based high-throughput screening assay for identification of UBC13 inhibitors. J Biomol Screen 2012; 17:163-76. [PMID: 22034497 PMCID: PMC4172584 DOI: 10.1177/1087057111423417] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
UBC13 is a noncanonical ubiquitin conjugating enzyme (E2) that has been implicated in a variety of cellular signaling processes due to its ability to catalyze formation of lysine 63-linked polyubiquitin chains on various substrates. In particular, UBC13 is required for signaling by a variety of receptors important in immune regulation, making it a candidate target for inflammatory diseases. UBC13 is also critical for double-strand DNA repair and thus a potential radiosensitizer and chemosensitizer target for oncology. The authors developed a high-throughput screening (HTS) assay for UBC13 based on the method of time-resolved fluorescence resonance energy transfer (TR-FRET). The TR-FRET assay combines fluorochrome (Fl)-conjugated ubiquitin (fluorescence acceptor) with terbium (Tb)-conjugated ubiquitin (fluorescence donor), such that the assembly of mixed chains of Fl- and Tb-ubiquitin creates a robust TR-FRET signal. The authors defined conditions for optimized performance of the TR-FRET assay in both 384- and 1536-well formats. Chemical library screens (total 456 865 compounds) were conducted in high-throughput mode using various compound collections, affording superb Z' scores (typically >0.7) and thus validating the performance of the assays. Altogether, the HTS assays described here are suitable for large-scale, automated screening of chemical libraries in search of compounds with inhibitory activity against UBC13.
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Affiliation(s)
- Charitha Madiraju
- Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
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Abstract
The NF-κB pathway is a central signaling pathway for inflammatory and immune responses, and aberrant NF-κB signaling is implicated multiple disorders, such as cancer and autoimmune, chronic inflammatory and metabolic diseases. NF-κB is regulated by various post-translational modifications, including phosphorylation and multiple ubiquitinations. We determined that LUBAC (linear ubiquitin chain assembly complex), composed of SHARPIN, HOIL-IL and HOIP, generates a novel type of Met1-linked linear polyubiquitin chain and specifically regulates the canonical NF-κB pathway via the linear ubiquitination of NEMO and RIP1. In the absence of LUBAC components, NF-κB signaling was attenuated and induced apoptosis and inflammation. Many studies on the pathophysiological functions of LUBAC, such as in B cell development, innate immune response, carcinogenesis, and osteogenesis, have been performed recently. This review summarizes these new findings on LUBAC- and linear ubiquitination-mediated NF-κB regulation and their implications in disorders.
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Affiliation(s)
- Fuminori Tokunaga
- Laboratory of Molecular Cell Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan.
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7
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Wilson RC, Edmondson SP, Flatt JW, Helms K, Twigg PD. The E2-25K ubiquitin-associated (UBA) domain aids in polyubiquitin chain synthesis and linkage specificity. Biochem Biophys Res Commun 2011; 405:662-6. [PMID: 21281599 DOI: 10.1016/j.bbrc.2011.01.089] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 01/25/2011] [Indexed: 11/18/2022]
Abstract
E2-25K is an ubiquitin-conjugating enzyme with the ability to synthesize Lys48-linked polyubiquitin chains. E2-25K and its homologs represent the only known E2 enzymes which contain a C-terminal ubiquitin-associated (UBA) domain as well as the conserved catalytic ubiquitin-conjugating (UBC) domain. As an additional non-covalent binding surface for ubiquitin, the UBA domain must provide some functional specialization. We mapped the protein-protein interface involved in the E2-25K UBA/ubiquitin complex by solution nuclear magnetic resonance (NMR) spectroscopy and subsequently modeled the structure of the complex. Domain-domain interactions between the E2-25K catalytic UBC domain and the UBA domain do not induce significant structural changes in the UBA domain or alter the affinity of the UBA domain for ubiquitin. We determined that one of the roles of the C-terminal UBA domain, in the context of E2-25K, is to increase processivity in Lys48-linked polyubiquitin chain synthesis, possibly through increased binding to the ubiquitinated substrate. Additionally, we see evidence that the UBA domain directs specificity in polyubiquitin chain linkage.
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Affiliation(s)
- Randall C Wilson
- Laboratory for Structural Biology, University of Alabama in Huntsville, Huntsville, AL 35899, USA
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Xia ZP, Sun L, Chen X, Pineda G, Jiang X, Adhikari A, Zeng W, Chen ZJ. Direct activation of protein kinases by unanchored polyubiquitin chains. Nature 2009; 461:114-9. [PMID: 19675569 PMCID: PMC2747300 DOI: 10.1038/nature08247] [Citation(s) in RCA: 436] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Accepted: 06/29/2009] [Indexed: 12/27/2022]
Abstract
TRAF6 is a ubiquitin ligase that is essential for the activation of NF-kappaB and MAP kinases in several signalling pathways, including those emanating from the interleukin 1 and Toll-like receptors. TRAF6 functions together with a ubiquitin-conjugating enzyme complex consisting of UBC13 (also known as UBE2N) and UEV1A (UBE2V1) to catalyse Lys 63-linked polyubiquitination, which activates the TAK1 (also known as MAP3K7) kinase complex. TAK1 in turn phosphorylates and activates IkappaB kinase (IKK), leading to the activation of NF-kappaB. Although several proteins are known to be polyubiquitinated in the IL1R and Toll-like receptor pathways, it is not clear whether ubiquitination of any of these proteins is important for TAK1 or IKK activation. By reconstituting TAK1 activation in vitro using purified proteins, here we show that free Lys 63 polyubiquitin chains, which are not conjugated to any target protein, directly activate TAK1 by binding to the ubiquitin receptor TAB2 (also known as MAP3K7IP2). This binding leads to autophosphorylation and activation of TAK1. Furthermore, we found that unanchored polyubiquitin chains synthesized by TRAF6 and UBCH5C (also known as UBE2D3) activate the IKK complex. Disassembly of the polyubiquitin chains by deubiquitination enzymes prevented TAK1 and IKK activation. These results indicate that unanchored polyubiquitin chains directly activate TAK1 and IKK, suggesting a new mechanism of protein kinase regulation.
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Affiliation(s)
- Zong-Ping Xia
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Lijun Sun
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Xiang Chen
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Gabriel Pineda
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Xiaomo Jiang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Anirban Adhikari
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Wenwen Zeng
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
| | - Zhijian J. Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148
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Chastagner P, Israël A, Brou C. Itch/AIP4 mediates Deltex degradation through the formation of K29-linked polyubiquitin chains. EMBO Rep 2006; 7:1147-53. [PMID: 17028573 PMCID: PMC1679774 DOI: 10.1038/sj.embor.7400822] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 07/14/2006] [Accepted: 08/01/2006] [Indexed: 01/06/2023] Open
Abstract
Deltex (DTX) and AIP4 are the human orthologues of the Drosophila deltex and Suppressor of deltex, which have been genetically described as being antagonistically involved in the Notch signalling pathway. Both genes encode E3 ubiquitin ligases of the RING (Really interesting new gene)-H2 and HECT (Homologous to E6AP carboxyl terminus) families, respectively. In an attempt to understand the molecular basis of their genetic interactions, we studied the relationship between DTX and AIP4 in the absence of activation of the Notch pathway. We show here that both molecules interact and partially colocalize to endocytic vesicles, and that AIP4 targets DTX for lysosomal degradation. Furthermore, AIP4-generated polyubiquitin chains are mainly conjugated through lysine 29 of ubiquitin in vivo, indicating a link between this type of chain and lysosomal degradation.
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Affiliation(s)
- Patricia Chastagner
- Unité de Signalisation Moléculaire et Activation Cellulaire, URA 2582, CNRS, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
| | - Alain Israël
- Unité de Signalisation Moléculaire et Activation Cellulaire, URA 2582, CNRS, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
| | - Christel Brou
- Unité de Signalisation Moléculaire et Activation Cellulaire, URA 2582, CNRS, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
- Tel: +33 1 40 61 30 41; Fax: +33 1 40 61 30 40; E-mail:
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Hau DD, Lewis MJ, Saltibus LF, Pastushok L, Xiao W, Spyracopoulos L. Structure and interactions of the ubiquitin-conjugating enzyme variant human Uev1a: implications for enzymatic synthesis of polyubiquitin chains. Biochemistry 2006; 45:9866-77. [PMID: 16893187 DOI: 10.1021/bi060631r] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Lys(63)-linked polyubiquitination of TRAF2 or TRAF6 is an essential step within the signal transduction cascade responsible for activation of p38, c-Jun N-terminal kinase, and the transcription factor NF-kappaB. Attachment of ubiquitin (Ub) to a TRAF, and conjugation of Ub molecules to form a polyUb chain, is catalyzed by a heterodimer composed of a catalytically active E2 (hUbc13), involved in covalent bond transfer, and hUev1a, an E2-like protein involved in substrate Ub binding. Given the key biochemical processes in which hUev1a is involved, it is important to determine the molecular basis of the catalytic mechanism for Lys(63)-linked protein ubiquitination. Nuclear magnetic resonance (NMR) spectroscopy was used to determine the structure of hUev1a and its interactions with Ub and hUbc13. A structural model for the Ub-hUev1a-hUbc13-Ub tetramer was developed to gain chemical insight into the synthesis of Lys(63)-linked Ub chains. We propose that a network of hydrogen bonds involving hUbc13-Asp(81) and Ub-Glu(64) positions Ub-Lys(63) proximal to the active site. Interestingly, restrained molecular dynamics simulations in implicit solvent indicate that deprotonation of Ub-Lys(63) does not involve a general Asp or Glu base and may occur when the amino group approaches the thioester carbonyl carbon near the Bürgi-Dunitz trajectory.
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Affiliation(s)
- D Duong Hau
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Abstract
Protein degradation by 26S proteasomes requires the coordinated action of multiple binding and catalytic activities to process ubiquitinated protein substrates. For the purpose of studying conjugate degradation independently of substrate targeting and unfolding steps, we have developed substrates based on an N-terminal fusion of ubiquitin to an irreversibly unfolded protein, the 83 amino acid HA epitope-tagged first domain of chicken ovomucoid. Fluorescent labeling of the six cysteines in the ovomucoid moiety (OM) with Lucifer Yellow iodoacetamide yields UbOM(LY); the ubiquitin in the fusion protein can be extended by the addition of a K48-linked polyubiquitin chain to form Ub(n)OM(LY). UbOM(LY) derivatives provide versatile substrates to monitor both protein degradation and deubiquitination by 26S proteasomes in vitro. Comparisons of polyubiquitin conjugates of unfolded OM(LY) with folded dihydrofolate reductase (DHFR) in degradation assays can help resolve and identify the rate-limiting steps in proteasome degradation.
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Affiliation(s)
- Tingting Yao
- Stowers Institute For Medical Research, Kansas City, MO 64110, USA
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Gazdoiu S, Yamoah K, Wu K, Escalante CR, Tappin I, Bermudez V, Aggarwal AK, Hurwitz J, Pan ZQ. Proximity-induced activation of human Cdc34 through heterologous dimerization. Proc Natl Acad Sci U S A 2005; 102:15053-8. [PMID: 16210246 PMCID: PMC1242854 DOI: 10.1073/pnas.0507646102] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cdc34 is an E2-conjugating enzyme required for catalyzing the polyubiquitination reaction mediated by the Skp1.CUL1.F-box (SCF) protein E3 ubiquitin (Ub) ligase. Here, we show that the activity of human Cdc34 in the Ub-Ub ligation reaction was enhanced dramatically by SCF's core Ub ligase module, composed of a heterodimeric complex formed by the ROC1 RING finger protein and the CUL1 C terminus that contains a Nedd8 moiety covalently conjugated at K720. Unexpectedly, we found that N-terminal fusion of a GST moiety to human Cdc34 generated dimeric GST-Cdc34 that was constitutively active in supporting the assembly of K48-linked polyUb chains independently of SCF. Furthermore, fusion of a FK506-binding protein (FKBP) to the N terminus of human Cdc34 yielded FKBP-Cdc34 that was induced to form a dimer upon treatment with the chemical inducer AP20187. The AP20187-induced dimeric form of FKBP-Cdc34 was substantially more active than the monomer in catalyzing Ub-Ub ligation. Thus, juxtaposition of human Cdc34 activates its catalytic capability, suggesting that the SCF-mediated polyubiquitination reaction may require the conversion of Cdc34 from an inactive monomer to a highly active dimeric form.
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Affiliation(s)
- Stefan Gazdoiu
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY 10029-6574, USA
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Saeki Y, Isono E, Oguchi T, Shimada M, Sone T, Kawahara H, Yokosawa H, Toh-e A. Intracellularly inducible, ubiquitin hydrolase-insensitive tandem ubiquitins inhibit the 26S proteasome activity and cell division. Genes Genet Syst 2005; 79:77-86. [PMID: 15215673 DOI: 10.1266/ggs.79.77] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We constructed polyubiquitin derivatives that contain a tandem repeat of ubiquitins and were insensitive to ubiquitin hydrolases. They were designated tandem ubiquitin (tUb) with the number of repeats, such as tUb2. When tUbs were expressed under the control of the GAL1 promoter in the wild-type yeast strain, growth was strongly inhibited. Under these conditions, the degradation of N-end rule substrates, a UFD substrate and Gcn4 was inhibited, indicating that the tUb inhibits 26S proteasome activity. Consistent with this, tUb binds to the 26S proteasome. We showed that tUb inhibited the in vitro degradation of polyubiquitinylated Sic1 by the 26S proteasome. When tUB6 messenger RNA was injected into Xenopus embryos, cell division was inhibited, suggesting that tUb can be used as a versatile inhibitor of the 26S proteasome.
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Affiliation(s)
- Yasushi Saeki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Tokyo 113-0033, Japan
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