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Polge C, Cabantous S, Taillandier D. Tripartite Split-GFP for High Throughput Screening of Small Molecules: A Powerful Strategy for Targeting Transient/Labile Interactors like E2-E3 Ubiquitination Enzymes. Chembiochem 2024; 25:e202300723. [PMID: 38088048 DOI: 10.1002/cbic.202300723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/05/2023] [Indexed: 01/13/2024]
Abstract
The search for inhibitors of the Ubiquitin Proteasome System (UPS) is an expanding area, due to the crucial role of UPS enzymes in several diseases. The complexity of the UPS and the multiple protein-protein interactions (PPIs) involved, either between UPS proteins themselves or between UPS components and theirs targets, offer an incredibly wide field for the development of chemical compounds for specifically modulating or inhibiting metabolic pathways. However, numerous UPS PPIs are transient/labile, due the processivity of the system (Ubiquitin [Ub] chain elongation, Ub transfer, etc.). Among the different strategies that can be used either for deciphering UPS PPI or for identifying/characterizing small compounds inhibitors, the split-GFP approach offers several advantages notably for high throughput screening of drugs. Split-GFP is based on the principle of protein-fragment complementation assay (PCA). PCA allows addressing PPIs by coupling each protein of interest (POI) to fragments of a reporter protein whose reconstitution is linked to the interaction of the POI. Here, we review the evolution of the split-GFP approach from bipartite to tripartite Split-GFP and its recent applicability for screening chemical compounds targeting the UPS.
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Affiliation(s)
- Cécile Polge
- Université Clermont Auvergne INRAE, UNH, Unité de Nutrition Humaine, F-63000, Clermont-Ferrand, France
| | - Stéphanie Cabantous
- Cancer Research Center of Toulouse INSERM UMR 1037, Université de Toulouse, F-31037, Toulouse, France
| | - Daniel Taillandier
- Université Clermont Auvergne INRAE, UNH, Unité de Nutrition Humaine, F-63000, Clermont-Ferrand, France
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2
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Lee HS, Bang I, You J, Jeong TK, Kim CR, Hwang M, Kim JS, Baek SH, Song JJ, Choi HJ. Molecular basis for PHF7-mediated ubiquitination of histone H3. Genes Dev 2023; 37:984-997. [PMID: 37993255 PMCID: PMC10760634 DOI: 10.1101/gad.350989.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023]
Abstract
The RING-type E3 ligase has been known for over two decades, yet its diverse modes of action are still the subject of active research. Plant homeodomain (PHD) finger protein 7 (PHF7) is a RING-type E3 ubiquitin ligase responsible for histone ubiquitination. PHF7 comprises three zinc finger domains: an extended PHD (ePHD), a RING domain, and a PHD. While the function of the RING domain is largely understood, the roles of the other two domains in E3 ligase activity remain elusive. Here, we present the crystal structure of PHF7 in complex with the E2 ubiquitin-conjugating enzyme (E2). Our structure shows that E2 is effectively captured between the RING domain and the C-terminal PHD, facilitating E2 recruitment through direct contact. In addition, through in vitro binding and functional assays, we demonstrate that the N-terminal ePHD recognizes the nucleosome via DNA binding, whereas the C-terminal PHD is involved in histone H3 recognition. Our results provide a molecular basis for the E3 ligase activity of PHF7 and uncover the specific yet collaborative contributions of each domain to the PHF7 ubiquitination activity.
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Affiliation(s)
- Hyun Sik Lee
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Injin Bang
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, New York 10016, USA
| | - Junghyun You
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Tae-Kyeong Jeong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Chang Rok Kim
- Creative Research Initiatives Center for Epigenetic Code and Diseases, School of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Minsang Hwang
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jong-Seo Kim
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Sung Hee Baek
- Creative Research Initiatives Center for Epigenetic Code and Diseases, School of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Ji-Joon Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Hee-Jung Choi
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea;
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3
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Welsh KA, Bolhuis DL, Nederstigt AE, Boyer J, Temple BRS, Bonacci T, Gu L, Ordureau A, Harper JW, Steimel JP, Zhang Q, Emanuele MJ, Harrison JS, Brown NG. Functional conservation and divergence of the helix-turn-helix motif of E2 ubiquitin-conjugating enzymes. EMBO J 2021; 41:e108823. [PMID: 34942047 PMCID: PMC8804933 DOI: 10.15252/embj.2021108823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 11/22/2021] [Accepted: 11/25/2021] [Indexed: 02/05/2023] Open
Abstract
Polyubiquitination by E2 and E3 enzymes is crucial to cell cycle control, epigenetic regulation, and development. The hallmark of the E2 family is the ubiquitin (Ub)-conjugating (UBC) domain that forms a dynamic thioester conjugate with ubiquitin (E2~Ub). Numerous studies have focused on E2 surfaces, such as the N-terminal and crossover helices, that directly interact with an E3 or the conjugated ubiquitin to stabilize the active, "closed" state of the E2~Ub. However, it remains unclear how other E2 surfaces regulate ubiquitin transfer. Here, we demonstrate the helix-turn-helix (HTH) motif of the UBC tunes the intrinsic polyubiquitination activity through distinct functions in different E2s. Interestingly, the E2HTH motif is repurposed in UBE2S and UBE2R2 to interact with the conjugated or acceptor ubiquitin, respectively, modulating ubiquitin transfer. Furthermore, we propose that Anaphase-Promoting Complex/Cyclosome binding to the UBE2SHTH reduces the conformational space of the flexible E2~Ub, demonstrating an atypical E3-dependent activation mechanism. Altogether, we postulate the E2HTH motif evolved to provide new functionalities that can be harnessed by E3s and permits additional regulation to facilitate specific E2-E3-mediated polyubiquitination.
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Affiliation(s)
- Kaeli A Welsh
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Derek L Bolhuis
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Joshua Boyer
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Brenda R S Temple
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,R L Juliano Structural Bioinformatics Core Facility, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Thomas Bonacci
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Li Gu
- Department of Chemistry, University of the Pacific, Stockton, CA, USA
| | - Alban Ordureau
- Department of Cell Biology, Blavatnik Institute of Harvard Medical School, Boston, MA, USA
| | - J Wade Harper
- Department of Cell Biology, Blavatnik Institute of Harvard Medical School, Boston, MA, USA
| | - Joshua P Steimel
- Department of Mechanical Engineering, University of the Pacific, Stockton, CA, USA
| | - Qi Zhang
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael J Emanuele
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Joseph S Harrison
- Department of Chemistry, University of the Pacific, Stockton, CA, USA
| | - Nicholas G Brown
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA
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4
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Arora H, Wilcox SM, Johnson LA, Munro L, Eyford BA, Pfeifer CG, Welch I, Jefferies WA. The ATP-Binding Cassette Gene ABCF1 Functions as an E2 Ubiquitin-Conjugating Enzyme Controlling Macrophage Polarization to Dampen Lethal Septic Shock. Immunity 2019; 50:418-431.e6. [PMID: 30770245 DOI: 10.1016/j.immuni.2019.01.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 05/30/2018] [Accepted: 01/24/2019] [Indexed: 12/16/2022]
Abstract
Sepsis is a bi-phasic inflammatory disease that threatens approximately 30 million lives and claims over 14 million annually, yet little is known regarding the molecular switches and pathways that regulate this disease. Here, we have described ABCF1, an ATP-Binding Cassette (ABC) family member protein, which possesses an E2 ubiquitin enzyme activity, through which it controls the Lipopolysaccharide (LPS)- Toll-like Receptor-4 (TLR4) mediated gram-negative insult by targeting key proteins for K63-polyubiquitination. Ubiquitination by ABCF1 shifts the inflammatory profile from an early phase MyD88-dependent to a late phase TRIF-dependent signaling pathway, thereby regulating TLR4 endocytosis and modulating macrophage polarization from M1 to M2 phase. Physiologically, ABCF1 regulates the shift from the inflammatory phase of sepsis to the endotoxin tolerance phase, and modulates cytokine storm and interferon-β (IFN-β)-dependent production by the immunotherapeutic mediator, SIRT1. Consequently, ABCF1 controls sepsis induced mortality by repressing hypotension-induced renal circulatory dysfunction.
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Affiliation(s)
- Hitesh Arora
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; The Vancouver Prostate Centre, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada; Department of Microbiology and Immunology, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada
| | - Sara Morgan Wilcox
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; Department of Microbiology and Immunology, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Laura Alexandra Johnson
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Department of Zoology, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Lonna Munro
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; The Vancouver Prostate Centre, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada
| | - Brett Alexander Eyford
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada
| | - Cheryl Gurine Pfeifer
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; The Vancouver Prostate Centre, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada
| | - Ian Welch
- Department of Pathology, UBC, 4145 Wesbrook Mall, Vancouver BC V6T 1W5, Canada
| | - Wilfred Arthur Jefferies
- Michael Smith Laboratories, University of British Columbia (UBC), 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada; The Vancouver Prostate Centre, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada; Department of Microbiology and Immunology, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Centre for Blood Research, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Department of Zoology, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Department of Medical Genetics, UBC, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada.
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5
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Abstract
Ubiquitin (Ub)-mediated protein degradation is a key cellular defense mechanism that detects and eliminates defective proteins. A major intracellular site of protein quality control degradation is the endoplasmic reticulum (ER), hence the term ER-associated degradation, or endoplasmic reticulum-associated degradation (ERAD). Yeast ERAD is composed of three Ub-protein conjugation complexes, named according to their E3 Ub-protein ligase components, Hrd1, Doa10, and the Asi complex, which resides at the nuclear envelope (NE). These ER/NE membrane-associated RING-type E3 ligases recognize and ubiquitylate defective proteins in cooperation with the E2 conjugating enzyme Ubc7 and the obligatory Ubc7 cofactor Cue1. Interaction of Ubc7 with the RING domains of its cognate E3 Ub-protein ligases stimulates the formation of isopeptide (amide) Ub-Ub linkages. Each isopeptide bond is formed by transfer of an Ubc7-linked activated Ub to a lysine side chain of an acceptor Ub. Multiple Ub transfer reactions form a poly-Ub chain that targets the conjugated protein for degradation by the proteasome. To study the mechanism of Ub-Ub bond formation, this reaction is reconstituted in a cell-free system consisting of recombinant E1, Ub, Ubc7, its cofactor Cue1, and the RING domain of either Doa10 or Hrd1. Here we provide detailed protocols for the purification of the required recombinant proteins and for the reactions that produce an Ub-Ub bond, specifically, the formation of an Ubc7~Ub thiolester (Ub charging) and subsequent formation of the isopeptide Ub-Ub linkage (Ub transfer). These protocols also provide a useful guideline for similar in vitro ubiquitylation reactions intended to explore the mechanism of other Ub-conjugation systems.
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Affiliation(s)
- Bayan Mashahreh
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yuval Reiss
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Reuven Wiener
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Hebrew University School of Medicine, Jerusalem, Israel
| | - Tommer Ravid
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
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6
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Hormaechea-Agulla D, Kim Y, Song MS, Song SJ. New Insights into the Role of E2s in the Pathogenesis of Diseases: Lessons Learned from UBE2O. Mol Cells 2018; 41:168-178. [PMID: 29562734 PMCID: PMC5881090 DOI: 10.14348/molcells.2018.0008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 03/08/2018] [Accepted: 03/13/2018] [Indexed: 12/23/2022] Open
Abstract
Intracellular communication via ubiquitin (Ub) signaling impacts all aspects of cell biology and regulates pathways critical to human development and viability; therefore aberrations or defects in Ub signaling can contribute to the pathogenesis of human diseases. Ubiquitination consists of the addition of Ub to a substrate protein via coordinated action of E1-activating, E2-conjugating and E3-ligating enzymes. Approximately 40 E2s have been identified in humans, and most are thought to be involved in Ub transfer; although little information is available regarding the majority of them, emerging evidence has highlighted their importance to human health and disease. In this review, we focus on recent insights into the pathogenetic roles of E2s (particularly the ubiquitin-conjugating enzyme E2O [UBE2O]) in debilitating diseases and cancer, and discuss the tantalizing prospect that E2s may someday serve as potential therapeutic targets for human diseases.
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Affiliation(s)
- Daniel Hormaechea-Agulla
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030,
USA
| | - Youngjo Kim
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan 31151,
Korea
| | - Min Sup Song
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030,
USA
- Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030,
USA
| | - Su Jung Song
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan 31151,
Korea
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7
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Abstract
Plant U-box type E3 ubiquitin ligases (PUBs) are well known for their functions in a variety of stress responses, including immune responses and the adaptation to abiotic stresses. First linked to pollen self-incompatibility, their repertoire of roles has grown to encompass also the regulation of developmental processes. Notably, new studies provide clues to their mode of action, underline the existence of conserved PUB-kinase modules, and suggest new links to G-protein signalling, placing PUBs at the crossroads of major signalling hubs. The frequent association with membranes, by interacting and/or targeting membrane proteins, as well as through a recently reported direct interaction with phospholipids, indicates a general function in the control of vesicle transport and their cargoes. This review aims to give an overview of the most significant advances in the field, while also trying to identify common themes of PUB function.
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Affiliation(s)
- Marco Trujillo
- Independent Junior Research Group-Ubiquitination in Immunity, Leibniz Institute of Plant Biochemistry, Germany
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8
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DiBello A, Datta AB, Zhang X, Wolberger C. Role of E2-RING Interactions in Governing RNF4-Mediated Substrate Ubiquitination. J Mol Biol 2016; 428:4639-4650. [PMID: 27678051 DOI: 10.1016/j.jmb.2016.09.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 02/06/2023]
Abstract
Members of the really interesting new gene (RING) E3 ubiquitin ligase family bind to both substrate and ubiquitin-charged E2 enzyme, promoting the transfer of ubiquitin from the E2 to substrate. Either a single ubiquitin or one of the several types of polyubiquitin chains can be conjugated to substrate proteins, with different types of ubiquitin modifications signaling the distinct outcomes. E2 enzymes play a central role in governing the nature of the ubiquitin modification, although the essential features of the E2 that differentiate mono- versus polyubiquitinating E2 enzymes remain unclear. RNF4 is a compact RING E3 ligase that directs the ubiquitination of polySUMO chains in concert with several different E2 enzymes. RNF4 monoubiquitinates polySUMO substrates in concert with RAD6B and polyubiquitinates substrates together with UBCH5B, a promiscuous E2 that can function with a broad range of E3 ligases. We find that the divergent ubiquitination activities of RAD6B and UBCH5B are governed by differences at the RING-binding surface of the E2. By mutating the RAD6B RING-binding surface to resemble that of UBCH5B, RAD6B can be transformed into a highly active UBCH5B-like E2 that polyubiquitinates SUMO chains in concert with RNF4. The switch in RAD6B activity correlates with increased affinity of the E2 for RNF4. These results point to an important role of the affinity between an E3 and its cognate E2 in governing the multiplicity of substrate ubiquitination.
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Affiliation(s)
- Anthony DiBello
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Ajit B Datta
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Xiangbin Zhang
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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9
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Abstract
Monoubiquitination of histone H2B at Lys123 in yeast plays a critical role in regulating transcription, mRNA export, DNA replication, and the DNA damage response. The RING E3 ligase, Bre1, catalyzes monoubiquitination of H2B in concert with the E2 ubiquitin-conjugating enzyme, Rad6. The crystal structure of a C-terminal fragment of Bre1 shows that the catalytic RING domain is preceded by an N-terminal helix that mediates coiled-coil interactions with a crystallographically related monomer. Homology modeling suggests that the human homologue of Bre1, RNF20/RNF40, heterodimerizes through similar coiled-coil interactions.
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Affiliation(s)
- Pankaj Kumar
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland, 21205
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland, 21205
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10
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Chong RA, Wu K, Spratt DE, Yang Y, Lee C, Nayak J, Xu M, Elkholi R, Tappin I, Li J, Hurwitz J, Brown BD, Chipuk JE, Chen ZJ, Sanchez R, Shaw GS, Huang L, Pan ZQ. Pivotal role for the ubiquitin Y59-E51 loop in lysine 48 polyubiquitination. Proc Natl Acad Sci U S A 2014; 111:8434-9. [PMID: 24912152 DOI: 10.1073/pnas.1407849111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lysine 48 (K48)-polyubiquitination is the predominant mechanism for mediating selective protein degradation, but the underlying molecular basis of selecting ubiquitin (Ub) K48 for linkage-specific chain synthesis remains elusive. Here, we present biochemical, structural, and cell-based evidence demonstrating a pivotal role for the Ub Y59-E51 loop in supporting K48-polyubiquitination. This loop is established by a hydrogen bond between Ub Y59's hydroxyl group and the backbone amide of Ub E51, as substantiated by NMR spectroscopic analysis. Loop residues Y59 and R54 are specifically required for the receptor activity enabling K48 to attack the donor Ub-E2 thiol ester in reconstituted ubiquitination catalyzed by Skp1-Cullin1-F-box (SCF)(βTrCP) E3 ligase and Cdc34 E2-conjugating enzyme. When introduced into mammalian cells, loop-disruptive mutant Ub(R54A/Y59A) diminished the production of K48-polyubiquitin chains. Importantly, conditional replacement of human endogenous Ub by Ub(R54A/Y59A) or Ub(K48R) yielded profound apoptosis at a similar extent, underscoring the global impact of the Ub Y59-E51 loop in cellular K48-polyubiquitination. Finally, disulfide cross-linking revealed interactions between the donor Ub-bound Cdc34 acidic loop and the Ub K48 site, as well as residues within the Y59-E51 loop, suggesting a mechanism in which the Ub Y59-E51 loop helps recruit the E2 acidic loop that aligns the receptor Ub K48 to the donor Ub for catalysis.
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11
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Bae H, Kim WT. Classification and interaction modes of 40 rice E2 ubiquitin-conjugating enzymes with 17 rice ARM-U-box E3 ubiquitin ligases. Biochem Biophys Res Commun 2014; 444:575-80. [PMID: 24486490 DOI: 10.1016/j.bbrc.2014.01.098] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 01/21/2014] [Indexed: 11/29/2022]
Abstract
Rice, a monocot model crop, contains at least 48 putative E2 ubiquitin (Ub)-conjugating enzymes. Based on homology comparisons with 40 Arabidopsis E2 proteins and 35 human E2s, 48 rice E2s were classified into 15 different groups. Yeast two-hybrid analyses using the U-box-domain regions of armadillo (ARM)-U-box E3 Ub-ligases and the Ub-conjugating (UBC) domains of E2s showed that, among 40 rice E2s, 11 E2s accounted for 70% of the interactions with 17 ARM-U-box E3s. Thus, a single E2 could interact with multiple ARM-U-box E3s, suggesting the presence of E2 hubs for E2-E3 interactions in rice. Rice SPL11 ARM-U-box E3 displayed distinct self-ubiquitination patterns, including poly-ubiquitination, mono-ubiquitination, or no ubiquitination, depending on different E2 partners. This suggests that the mode of ubiquitination of SPL11 E3 is critically influenced by individual E2s.
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Affiliation(s)
- Hansol Bae
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Woo Taek Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
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