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Zhang Z, Sie B, Chang A, Leng Y, Nardone C, Timms RT, Elledge SJ. Elucidation of E3 ubiquitin ligase specificity through proteome-wide internal degron mapping. Mol Cell 2023; 83:3377-3392.e6. [PMID: 37738965 PMCID: PMC10594193 DOI: 10.1016/j.molcel.2023.08.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 02/17/2023] [Revised: 06/07/2023] [Accepted: 08/17/2023] [Indexed: 09/24/2023]
Abstract
The ubiquitin-proteasome system plays a critical role in biology by regulating protein degradation. Despite their importance, precise recognition specificity is known for a few of the 600 E3s. Here, we establish a two-pronged strategy for identifying and mapping critical residues of internal degrons on a proteome-scale in HEK-293T cells. We employ global protein stability profiling combined with machine learning to identify 15,800 peptides likely to contain sequence-dependent degrons. We combine this with scanning mutagenesis to define critical residues for over 5,000 predicted degrons. Focusing on Cullin-RING ligase degrons, we generated mutational fingerprints for 219 degrons and developed DegronID, a computational algorithm enabling the clustering of degron peptides with similar motifs. CRISPR analysis enabled the discovery of E3-degron pairs, of which we uncovered 16 pairs that revealed extensive degron variability and structural determinants. We provide the visualization of these data on the public DegronID data browser as a resource for future exploration.
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Affiliation(s)
- Zhiqian Zhang
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Brandon Sie
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Aiquan Chang
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Yumei Leng
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher Nardone
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Richard T Timms
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Cambridge Institute of Therapeutic Immunology and Infectious Disease, Department of Medicine, University of Cambridge, Puddicombe Way, Cambridge CB2 0AW, UK
| | - Stephen J Elledge
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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Adamson RJ, Payne NC, Bartual SG, Mazitschek R, Bullock AN. Structural and biochemical characterization establishes a detailed understanding of KEAP1-CUL3 complex assembly. Free Radic Biol Med 2023; 204:215-225. [PMID: 37156295 PMCID: PMC10564622 DOI: 10.1016/j.freeradbiomed.2023.04.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/22/2023] [Accepted: 04/28/2023] [Indexed: 05/10/2023]
Abstract
KEAP1 promotes the ubiquitin-dependent degradation of NRF2 by assembling into a CUL3-dependent ubiquitin ligase complex. Oxidative and electrophilic stress inhibit KEAP1 allowing NRF2 to accumulate for the transactivation of stress response genes. To date there are no structures of the KEAP1-CUL3 interaction nor binding data to show the contributions of different domains to their binding affinity. We determined a crystal structure of the BTB and 3-box domains of human KEAP1 in complex with the CUL3 N-terminal domain that showed a heterotetrameric assembly with 2:2 stoichiometry. To support the structural data, we developed a versatile TR-FRET-based assay system to profile the binding of BTB-domain-containing proteins to CUL3 and determine the contribution of distinct protein features, revealing the importance of the CUL3 N-terminal extension for high affinity binding. We further provide direct evidence that the investigational drug CDDO does not disrupt the KEAP1-CUL3 interaction, even at high concentrations, but reduces the affinity of KEAP1-CUL3 binding. The TR-FRET-based assay system offers a generalizable platform for profiling this protein class and may form a suitable screening platform for ligands that disrupt these interactions by targeting the BTB or 3-box domains to block E3 ligase function.
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Affiliation(s)
- Roslin J Adamson
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - N Connor Payne
- Center for Systems Biology, Massachusetts General Hospital, Boston, MA, 02114, USA; Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Sergio G Bartual
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Ralph Mazitschek
- Center for Systems Biology, Massachusetts General Hospital, Boston, MA, 02114, USA; Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
| | - Alex N Bullock
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.
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3
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Abstract
Neddylation, a ubiquitylation-like post-translational modification, is catalyzed by a cascade composed of three enzymes: E1 activating enzyme, E2 conjugating enzyme, and E3 ligase with cullins as physiological substrates. Specifically, neddylation E2 UBE2M couples with E3 RBX1 to neddylate cullins 1-4, whereas neddylation E2 UBE2F couples with E3 RBX2/SAG to neddylate cullin 5, leading to activation of CRL1-4 (Cullin-RING ligases 1-4) and CRL5, respectively. While over-activation of the neddylation-CRLs axis occurs frequently in many human cancers, how neddylation-CRLs regulate the function of immune cells, particularly Treg cells was previously unknown. To this end, we recently performed Treg selective knockout of two neddylation E2s and two E3s, individually, driven by Foxp3-Cre, and found that while the Ube2f-Sag E2/E3 pair plays a minimal role, if any, the Ube2m-Rbx1 pair is essential for the maintenance of Treg functionality, since their deletion triggers robust inflammatory response with autoimmune phenotypes. Milder phenotype severity upon Treg KO of upstream Ube2m than that of downstream Rbx1 strongly suggested that Rbx1 regulates Treg function in a manner dependent and independent of neddylation.
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Affiliation(s)
- Di Wu
- Cancer Institute of the Second Affiliated Hospital and Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Cancer Center, Zhejiang University, Hangzhou, Zhejiang, China
- Research Center for Life Science and Human Health, Binjiang Institute of Zhejiang University, Hangzhou, Zhejiang, China
| | - Yi Sun
- Cancer Institute of the Second Affiliated Hospital and Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Cancer Center, Zhejiang University, Hangzhou, Zhejiang, China
- Research Center for Life Science and Human Health, Binjiang Institute of Zhejiang University, Hangzhou, Zhejiang, China
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Schweiggert J, Habeck G, Hess S, Mikus F, Beloshistov R, Meese K, Hata S, Knobeloch K, Melchior F. SCF Fbxw5 targets kinesin-13 proteins to facilitate ciliogenesis. EMBO J 2021; 40:e107735. [PMID: 34368969 PMCID: PMC8441365 DOI: 10.15252/embj.2021107735] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 01/14/2021] [Revised: 06/29/2021] [Accepted: 07/12/2021] [Indexed: 11/23/2022] Open
Abstract
Microtubule depolymerases of the kinesin-13 family play important roles in various cellular processes and are frequently overexpressed in different cancer types. Despite the importance of their correct abundance, remarkably little is known about how their levels are regulated in cells. Using comprehensive screening on protein microarrays, we identified 161 candidate substrates of the multi-subunit ubiquitin E3 ligase SCFFbxw5 , including the kinesin-13 member Kif2c/MCAK. In vitro reconstitution assays demonstrate that MCAK and its closely related orthologs Kif2a and Kif2b become efficiently polyubiquitylated by neddylated SCFFbxw5 and Cdc34, without requiring preceding modifications. In cells, SCFFbxw5 targets MCAK for proteasomal degradation predominantly during G2 . While this seems largely dispensable for mitotic progression, loss of Fbxw5 leads to increased MCAK levels at basal bodies and impairs ciliogenesis in the following G1 /G0 , which can be rescued by concomitant knockdown of MCAK, Kif2a or Kif2b. We thus propose a novel regulatory event of ciliogenesis that begins already within the G2 phase of the preceding cell cycle.
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Affiliation(s)
- Jörg Schweiggert
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
| | - Gregor Habeck
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
| | - Sandra Hess
- Institute of NeuropathologyFaculty of MedicineUniversity of FreiburgFreiburgGermany
- Faculty of BiologyUniversity of FreiburgFreiburgGermany
| | - Felix Mikus
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
| | - Roman Beloshistov
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
| | - Klaus Meese
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
| | - Shoji Hata
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
| | | | - Frauke Melchior
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)University of HeidelbergDKFZ ‐ ZMBH AllianceHeidelbergGermany
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Bi Y, Cui D, Xiong X, Zhao Y. The characteristics and roles of β-TrCP1/2 in carcinogenesis. FEBS J 2020; 288:3351-3374. [PMID: 33021036 DOI: 10.1111/febs.15585] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [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: 07/07/2020] [Revised: 09/02/2020] [Accepted: 10/01/2020] [Indexed: 12/11/2022]
Abstract
β-transducin repeat-containing protein (β-TrCP), one of the well-characterized F-box proteins, acts as a substrate receptor and constitutes an active SCFβ-TrCP E3 ligase with a scaffold protein CUL1, a RING protein RBX1, and an adaptor protein SKP1. β-TrCP plays a critical role in the regulation of various physiological and pathological processes, including signal transduction, cell cycle progression, cell migration, DNA damage response, and tumorigenesis, by governing burgeoning amounts of key regulators for ubiquitination and proteasomal degradation. Given that a variety of β-TrCP substrates are well-known oncoproteins and tumor suppressors, and dysregulation of β-TrCP is frequently identified in human cancers, β-TrCP plays a vital role in carcinogenesis. In this review, we first briefly introduce the characteristics of β-TrCP1, β-TrCP2, and SCFβ-TrCP ubiquitin ligase, and then discuss SCFβ-TrCP ubiquitin ligase regulated biological processes by targeting its substrates for degradation. Moreover, we summarize the regulation of β-TrCP1 and β-TrCP2 at multiple layers and further discuss the various roles of β-TrCP1 and β-TrCP2 in human cancer, functioning as either an oncoprotein or a tumor suppressor in a manner dependent of cellular context. Finally, we provide novel insights for future perspectives on the potential of targeting β-TrCP1 and β-TrCP2 for cancer therapy.
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Affiliation(s)
- Yanli Bi
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Danrui Cui
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiufang Xiong
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yongchao Zhao
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
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6
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Chen Z, Picaud S, Filippakopoulos P, D'Angiolella V, Bullock AN. Structural Basis for Recruitment of DAPK1 to the KLHL20 E3 Ligase. Structure 2019; 27:1395-1404.e4. [PMID: 31279627 DOI: 10.1016/j.str.2019.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 05/26/2019] [Accepted: 06/03/2019] [Indexed: 12/31/2022]
Abstract
BTB-Kelch proteins form the largest subfamily of Cullin-RING E3 ligases, yet their substrate complexes are mapped and structurally characterized only for KEAP1 and KLHL3. KLHL20 is a related CUL3-dependent ubiquitin ligase linked to autophagy, cancer, and Alzheimer's disease that promotes the ubiquitination and degradation of substrates including DAPK1, PML, and ULK1. We identified an “LPDLV”-containing motif in the DAPK1 death domain that determines its recruitment and degradation by KLHL20. A 1.1-Å crystal structure of a KLHL20 Kelch domain-DAPK1 peptide complex reveals DAPK1 binding as a loose helical turn that inserts deeply into the central pocket of the Kelch domain to contact all six blades of the β propeller. Here, KLHL20 forms salt-bridge and hydrophobic interactions including tryptophan and cysteine residues ideally positioned for covalent inhibitor development. The structure highlights the diverse binding modes of β-propeller domains versus linear grooves and suggests a new target for structure-based drug design. An “LPDLV” motif in DAPK1 determines its recruitment and degradation by KLHL20 1.1-Å crystal structure determined of a KLHL20 Kelch domain-DAPK1 peptide complex A DAPK1 helical turn inserts into the β propeller to contact all six Kelch repeats KLHL20 shows a hydrophobic binding pocket suitable for inhibitor development
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Lin S, Shang Z, Li S, Gao P, Zhang Y, Hou S, Qin P, Dong Z, Hu T, Chen P. Neddylation inhibitor MLN4924 induces G 2 cell cycle arrest, DNA damage and sensitizes esophageal squamous cell carcinoma cells to cisplatin. Oncol Lett 2017; 15:2583-2589. [PMID: 29434977 DOI: 10.3892/ol.2017.7616] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [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: 10/23/2016] [Accepted: 11/02/2017] [Indexed: 12/14/2022] Open
Abstract
Inhibiting the protein neddylation pathway using the NEDD8-activating enzyme inhibitor MLN4924 represents an attractive anticancer strategy having been demonstrated to exhibit promising anticancer efficacy and with tolerable levels of toxicity; however, the mechanism by which MLN4924 inhibits cell proliferation in human esophageal squamous cell carcinoma (ESCC) cells requires further investigation. The present study revealed that MLN4924 treatment led to G2 cell cycle arrest and enhanced the protein stability of Wee1-like protein kinase and cyclin dependent protein kinase inhibitor 1A and B and p27. Furthermore, MLN4924 induced DNA damage and sensitized esophageal cancer cells to cisplatin by enhancing apoptosis. These findings extend the understanding of the function and mechanism of MLN4924 in ESCC and provide further evidence for the future development of neddylation inhibitors in clinical trials of esophageal cancer therapy, either alone or in combination.
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Affiliation(s)
- Shan Lin
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Zhaoyang Shang
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Shuo Li
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Peng Gao
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Yi Zhang
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Shuaiheng Hou
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Peng Qin
- Department of Immunotherapy, Henan Cancer Hospital and Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, Henan 450008, P.R. China
| | - Ziming Dong
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Tao Hu
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
| | - Ping Chen
- Department of Basic Science of Oncology, College of Basic Medical Sciences, Zhengzhou University, Collaborative Innovation Center of Henan Province for Cancer Chemoprevention, Zhengzhou, Henan 450001, P.R. China
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Pinkas DM, Sanvitale CE, Bufton JC, Sorrell FJ, Solcan N, Chalk R, Doutch J, Bullock AN. Structural complexity in the KCTD family of Cullin3-dependent E3 ubiquitin ligases. Biochem J 2017; 474:3747-3761. [PMID: 28963344 PMCID: PMC5664961 DOI: 10.1042/bcj20170527] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [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: 07/02/2017] [Revised: 09/21/2017] [Accepted: 09/25/2017] [Indexed: 12/25/2022]
Abstract
Members of the potassium channel tetramerization domain (KCTD) family are soluble non-channel proteins that commonly function as Cullin3 (Cul3)-dependent E3 ligases. Solution studies of the N-terminal BTB domain have suggested that some KCTD family members may tetramerize similarly to the homologous tetramerization domain (T1) of the voltage-gated potassium (Kv) channels. However, available structures of KCTD1, KCTD5 and KCTD9 have demonstrated instead pentameric assemblies. To explore other phylogenetic clades within the KCTD family, we determined the crystal structures of the BTB domains of a further five human KCTD proteins revealing a rich variety of oligomerization architectures, including monomer (SHKBP1), a novel two-fold symmetric tetramer (KCTD10 and KCTD13), open pentamer (KCTD16) and closed pentamer (KCTD17). While these diverse geometries were confirmed by small-angle X-ray scattering (SAXS), only the pentameric forms were stable upon size-exclusion chromatography. With the exception of KCTD16, all proteins bound to Cul3 and were observed to reassemble in solution as 5 : 5 heterodecamers. SAXS data and structural modelling indicate that Cul3 may stabilize closed BTB pentamers by binding across their BTB-BTB interfaces. These extra interactions likely also allow KCTD proteins to bind Cul3 without the expected 3-box motif. Overall, these studies reveal the KCTD family BTB domain to be a highly versatile scaffold compatible with a range of oligomeric assemblies and geometries. This observed interface plasticity may support functional changes in regulation of this unusual E3 ligase family.
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Affiliation(s)
- Daniel M Pinkas
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K
| | - Caroline E Sanvitale
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K
| | - Joshua C Bufton
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K
| | - Fiona J Sorrell
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K
| | - Nicolae Solcan
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K
| | - Rod Chalk
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K
| | - James Doutch
- ISIS Pulsed Neutron and Muon Source, STFC, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Alex N Bullock
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, U.K.
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Dove KK, Kemp HA, Di Bona KR, Reiter KH, Milburn LJ, Camacho D, Fay DS, Miller DL, Klevit RE. Two functionally distinct E2/E3 pairs coordinate sequential ubiquitination of a common substrate in Caenorhabditis elegans development. Proc Natl Acad Sci U S A 2017; 114:E6576-84. [PMID: 28739890 DOI: 10.1073/pnas.1705060114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ubiquitination, the crucial posttranslational modification that regulates the eukaryotic proteome, is carried out by a trio of enzymes, known as E1 [ubiquitin (Ub)-activating enzyme], E2 (Ub-conjugating enzyme), and E3 (Ub ligase). Although most E2s can work with any of the three mechanistically distinct classes of E3s, the E2 UBCH7 is unable to function with really interesting new gene (RING)-type E3s, thereby restricting it to homologous to E6AP C-terminus (HECT) and RING-in-between-RING (RBR) E3s. The Caenorhabditis elegans UBCH7 homolog, UBC-18, plays a critical role in developmental processes through its cooperation with the RBR E3 ARI-1 (HHARI in humans). We discovered that another E2, ubc-3, interacts genetically with ubc-18 in an unbiased genome-wide RNAi screen in C. elegans These two E2s have nonoverlapping biochemical activities, and each is dedicated to distinct classes of E3s. UBC-3 is the ortholog of CDC34 that functions specifically with Cullin-RING E3 ligases, such as SCF (Skp1-Cullin-F-box). Our genetic and biochemical studies show that UBCH7 (UBC-18) and the RBR E3 HHARI (ARI-1) coordinate with CDC34 (UBC-3) and an SCF E3 complex to ubiquitinate a common substrate, a SKP1-related protein. We show that UBCH7/HHARI primes the substrate with a single Ub in the presence of CUL-1, and that CDC34 is required to build chains onto the Ub-primed substrate. Our study reveals that the association and coordination of two distinct E2/E3 pairs play essential roles in a developmental pathway and suggests that cooperative action among E3s is a conserved feature from worms to humans.
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10
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Abstract
Ubiquitination is a highly conserved post-translational modification in eukaryotes, well known for targeting proteins for degradation by the 26S proteasome. Proteins destined for proteasomal degradation are selected by E3 ubiquitin ligases. Cullin-RING E3 ubiquitin ligases (CRLs) are the largest superfamily of E3 ubiquitin ligases, with over 400 members known in mammals. These modular complexes are tightly regulated in the cell. In this chapter, we highlight recent structural and biochemical advances shedding light on the assembly and architecture of cullin-RING ligases, their dynamic regulation by a variety of host factors, and their manipulation by viral pathogens and small molecules.
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Affiliation(s)
- Henry C Nguyen
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06511, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, 94158, USA
| | - Wei Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06511, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06511, USA.
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