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Lange SM, McFarland MR, Lamoliatte F, Carroll T, Krshnan L, Pérez-Ràfols A, Kwasna D, Shen L, Wallace I, Cole I, Armstrong LA, Knebel A, Johnson C, De Cesare V, Kulathu Y. VCP/p97-associated proteins are binders and debranching enzymes of K48-K63-branched ubiquitin chains. Nat Struct Mol Biol 2024:10.1038/s41594-024-01354-y. [PMID: 38977901 DOI: 10.1038/s41594-024-01354-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 06/13/2024] [Indexed: 07/10/2024]
Abstract
Branched ubiquitin (Ub) chains constitute a sizable fraction of Ub polymers in human cells. Despite their abundance, our understanding of branched Ub function in cell signaling has been stunted by the absence of accessible methods and tools. Here we identify cellular branched-chain-specific binding proteins and devise approaches to probe K48-K63-branched Ub function. We establish a method to monitor cleavage of linkages within complex Ub chains and unveil ATXN3 and MINDY as debranching enzymes. We engineer a K48-K63 branch-specific nanobody and reveal the molecular basis of its specificity in crystal structures of nanobody-branched Ub chain complexes. Using this nanobody, we detect increased K48-K63-Ub branching following valosin-containing protein (VCP)/p97 inhibition and after DNA damage. Together with our discovery that multiple VCP/p97-associated proteins bind to or debranch K48-K63-linked Ub, these results suggest a function for K48-K63-branched chains in VCP/p97-related processes.
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Affiliation(s)
- Sven M Lange
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK.
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
| | - Matthew R McFarland
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Frederic Lamoliatte
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Thomas Carroll
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Logesvaran Krshnan
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Anna Pérez-Ràfols
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Dominika Kwasna
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
- Malopolska Centre of Biotechnology (MCB), Jagiellonian University, Krakow, Poland
| | - Linnan Shen
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Iona Wallace
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Isobel Cole
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Lee A Armstrong
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Axel Knebel
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Clare Johnson
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Virginia De Cesare
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Yogesh Kulathu
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK.
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2
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Kliza KW, Song W, Pinzuti I, Schaubeck S, Kunzelmann S, Kuntin D, Fornili A, Pandini A, Hofmann K, Garnett JA, Stieglitz B, Husnjak K. N4BP1 functions as a dimerization-dependent linear ubiquitin reader which regulates TNF signalling. Cell Death Discov 2024; 10:183. [PMID: 38643192 PMCID: PMC11032371 DOI: 10.1038/s41420-024-01913-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/05/2024] [Accepted: 03/11/2024] [Indexed: 04/22/2024] Open
Abstract
Signalling through TNFR1 modulates proinflammatory gene transcription and programmed cell death, and its impairment causes autoimmune diseases and cancer. NEDD4-binding protein 1 (N4BP1) is a critical suppressor of proinflammatory cytokine production that acts as a regulator of innate immune signalling and inflammation. However, our current understanding about the molecular properties that enable N4BP1 to exert its suppressive potential remain limited. Here, we show that N4BP1 is a novel linear ubiquitin reader that negatively regulates NFκB signalling by its unique dimerization-dependent ubiquitin-binding module that we named LUBIN. Dimeric N4BP1 strategically positions two non-selective ubiquitin-binding domains to ensure preferential recognition of linear ubiquitin. Under proinflammatory conditions, N4BP1 is recruited to the nascent TNFR1 signalling complex, where it regulates duration of proinflammatory signalling in LUBIN-dependent manner. N4BP1 deficiency accelerates TNFα-induced cell death by increasing complex II assembly. Under proapoptotic conditions, caspase-8 mediates proteolytic processing of N4BP1, resulting in rapid degradation of N4BP1 by the 26 S proteasome, and acceleration of apoptosis. In summary, our findings demonstrate that N4BP1 dimerization creates a novel type of ubiquitin reader that selectively recognises linear ubiquitin which enables the timely and coordinated regulation of TNFR1-mediated inflammation and cell death.
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Affiliation(s)
- Katarzyna W Kliza
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt (Main), Germany.
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany.
| | - Wei Song
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
- Department of Oncology, University of Oxford, Oxford, UK
| | - Irene Pinzuti
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Simone Schaubeck
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt (Main), Germany
| | - Simone Kunzelmann
- Structural Biology Science Technology Platform, Francis Crick Institute, London, UK
| | - David Kuntin
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt (Main), Germany
- Department of Biology, University of York, Wentworth Way, York, UK
| | - Arianna Fornili
- School of Physical and Chemical Sciences, Queen Mary University of London, London, UK
| | | | - Kay Hofmann
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - James A Garnett
- Centre for Host-Microbiome Interactions, Dental Institute, King's College London, London, UK
| | - Benjamin Stieglitz
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK.
| | - Koraljka Husnjak
- Institute of Biochemistry II, Goethe University School of Medicine, Frankfurt (Main), Germany.
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3
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Ma Z, Zeng Y, Wang M, Liu W, Zhou J, Wu C, Hou L, Yin B, Qiang B, Shu P, Peng X. N4BP1 mediates RAM domain-dependent notch signaling turnover during neocortical development. EMBO J 2023; 42:e113383. [PMID: 37807845 PMCID: PMC10646556 DOI: 10.15252/embj.2022113383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023] Open
Abstract
Notch signaling pathway activity, particularly fluctuations in the biologically active effector fragment NICD, is required for rapid and efficient dynamic regulation of proper fate decisions in stem cells. In this study, we identified NEDD4-binding protein 1 (N4BP1), which is highly expressed in the developing mouse cerebral cortex, as a negative modulator of Notch signaling dynamics in neural progenitor cells. Intriguingly, N4BP1 regulated NICD stability specifically after Notch1 S3 cleavage through ubiquitin-mediated degradation that depended on its RAM domain, not its PEST domain, as had been extensively and previously described. The CoCUN domain in N4BP1, particularly the "Phe-Pro" motif (862/863 amino acid), was indispensable for mediating NICD degradation. The Ring family E3 ligase Trim21 was, in contrast to other NEDD4 family members, required for N4BP1-regulated NICD degradation. Overexpression of N4BP1 in cortical neural progenitors promoted neural stem cell differentiation, whereas neural progenitor cells lacking N4BP1 were sensitized to Notch signaling, resulting in the maintenance of stem-like properties in neural progenitor cells and lower production of cortical neurons.
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Affiliation(s)
- Zhihua Ma
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Yi Zeng
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- Present address:
Department of Infectious Diseases, Institute for Viral Hepatitis, The Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education)The Second Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Ming Wang
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- Present address:
Department of Otolaryngology, Head and Neck Surgery, Beijing Tongren HospitalCapital Medical University, Beijing Key Laboratory of Nasal Diseases, Beijing Institute of OtolaryngologyBeijingChina
| | - Wei Liu
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Jiafeng Zhou
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Chao Wu
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
| | - Lin Hou
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- State Key Laboratory of Common Mechanism Research for Major DiseasesBeijingChina
| | - Bin Yin
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- State Key Laboratory of Common Mechanism Research for Major DiseasesBeijingChina
| | - Boqin Qiang
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- State Key Laboratory of Common Mechanism Research for Major DiseasesBeijingChina
| | - Pengcheng Shu
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- State Key Laboratory of Common Mechanism Research for Major DiseasesBeijingChina
- Chinese Institute for Brain ResearchBeijingChina
| | - Xiaozhong Peng
- Department of Molecular Biology and Biochemistry, Medical Primate Research Center, Neuroscience CenterInstitute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical CollegeBeijingChina
- State Key Laboratory of Respiratory Health and MultimorbidityBeijingChina
- Institute of Laboratory Animal ScienceChinese Academy of Medical Sciences, Peking Union Medical CollegeBeijingChina
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4
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Lista MJ, Ficarelli M, Wilson H, Kmiec D, Youle RL, Wanford J, Winstone H, Odendall C, Taylor IA, Neil SJD, Swanson CM. A Nuclear Export Signal in KHNYN Required for Its Antiviral Activity Evolved as ZAP Emerged in Tetrapods. J Virol 2023; 97:e0087222. [PMID: 36633408 PMCID: PMC9888277 DOI: 10.1128/jvi.00872-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023] Open
Abstract
The zinc finger antiviral protein (ZAP) inhibits viral replication by directly binding CpG dinucleotides in cytoplasmic viral RNA to inhibit protein synthesis and target the RNA for degradation. ZAP evolved in tetrapods and there are clear orthologs in reptiles, birds, and mammals. When ZAP emerged, other proteins may have evolved to become cofactors for its antiviral activity. KHNYN is a putative endoribonuclease that is required for ZAP to restrict retroviruses. To determine its evolutionary path after ZAP emerged, we compared KHNYN orthologs in mammals and reptiles to those in fish, which do not encode ZAP. This identified residues in KHNYN that are highly conserved in species that encode ZAP, including several in the CUBAN domain. The CUBAN domain interacts with NEDD8 and Cullin-RING E3 ubiquitin ligases. Deletion of the CUBAN domain decreased KHNYN antiviral activity, increased protein expression and increased nuclear localization. However, mutation of residues required for the CUBAN domain-NEDD8 interaction increased KHNYN abundance but did not affect its antiviral activity or cytoplasmic localization, indicating that Cullin-mediated degradation may control its homeostasis and regulation of protein turnover is separable from its antiviral activity. By contrast, the C-terminal residues in the CUBAN domain form a CRM1-dependent nuclear export signal (NES) that is required for its antiviral activity. Deletion or mutation of the NES increased KHNYN nuclear localization and decreased its interaction with ZAP. The final 2 positions of this NES are not present in fish KHNYN orthologs and we hypothesize their evolution allowed KHNYN to act as a ZAP cofactor. IMPORTANCE The interferon system is part of the innate immune response that inhibits viruses and other pathogens. This system emerged approximately 500 million years ago in early vertebrates. Since then, some genes have evolved to become antiviral interferon-stimulated genes (ISGs) while others evolved so their encoded protein could interact with proteins encoded by ISGs and contribute to their activity. However, this remains poorly characterized. ZAP is an ISG that arose during tetrapod evolution and inhibits viral replication. Because KHNYN interacts with ZAP and is required for its antiviral activity against retroviruses, we conducted an evolutionary analysis to determine how specific amino acids in KHNYN evolved after ZAP emerged. This identified a nuclear export signal that evolved in tetrapods and is required for KHNYN to traffic in the cell and interact with ZAP. Overall, specific residues in KHNYN evolved to allow it to act as a cofactor for ZAP antiviral activity.
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Affiliation(s)
- Maria J. Lista
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Mattia Ficarelli
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Harry Wilson
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Dorota Kmiec
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Rebecca L. Youle
- King’s College London, Department of Infectious Diseases, London, United Kingdom
- The Francis Crick Institute, Macromolecular Structure Laboratory, London, United Kingdom
| | - Joseph Wanford
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Helena Winstone
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Charlotte Odendall
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Ian A. Taylor
- The Francis Crick Institute, Macromolecular Structure Laboratory, London, United Kingdom
| | - Stuart J. D. Neil
- King’s College London, Department of Infectious Diseases, London, United Kingdom
| | - Chad M. Swanson
- King’s College London, Department of Infectious Diseases, London, United Kingdom
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Molecular Mechanisms of DUBs Regulation in Signaling and Disease. Int J Mol Sci 2021; 22:ijms22030986. [PMID: 33498168 PMCID: PMC7863924 DOI: 10.3390/ijms22030986] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/15/2021] [Accepted: 01/18/2021] [Indexed: 02/07/2023] Open
Abstract
The large family of deubiquitinating enzymes (DUBs) are involved in the regulation of a plethora of processes carried out inside the cell by protein ubiquitination. Ubiquitination is a basic pathway responsible for the correct protein homeostasis in the cell, which could regulate the fate of proteins through the ubiquitin–proteasome system (UPS). In this review we will focus on recent advances on the molecular mechanisms and specificities found for some types of DUBs enzymes, highlighting illustrative examples in which the regulatory mechanism for DUBs has been understood in depth at the molecular level by structural biology. DUB proteases are responsible for cleavage and regulation of the multiple types of ubiquitin linkages that can be synthesized inside the cell, known as the ubiquitin-code, which are tightly connected to specific substrate functions. We will display some strategies carried out by members of different DUB families to provide specificity on the cleavage of particular ubiquitin linkages. Finally, we will also discuss recent progress made for the development of drug compounds targeting DUB proteases, which are usually correlated to the progress of many pathologies such as cancer and neurodegenerative diseases.
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Integration of innate immune signalling by caspase-8 cleavage of N4BP1. Nature 2020; 587:275-280. [PMID: 32971525 DOI: 10.1038/s41586-020-2796-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 09/17/2020] [Indexed: 02/06/2023]
Abstract
Mutations in the death receptor FAS1,2 or its ligand FASL3 cause autoimmune lymphoproliferative syndrome, whereas mutations in caspase-8 or its adaptor FADD-which mediate cell death downstream of FAS and FASL-cause severe immunodeficiency in addition to autoimmune lymphoproliferative syndrome4-6. Mouse models have corroborated a role for FADD-caspase-8 in promoting inflammatory responses7-12, but the mechanisms that underlie immunodeficiency remain undefined. Here we identify NEDD4-binding protein 1 (N4BP1) as a suppressor of cytokine production that is cleaved and inactivated by caspase-8. N4BP1 deletion in mice increased the production of select cytokines upon stimulation of the Toll-like receptor (TLR)1-TLR2 heterodimer (referred to herein as TLR1/2), TLR7 or TLR9, but not upon engagement of TLR3 or TLR4. N4BP1 did not suppress TLR3 or TLR4 responses in wild-type macrophages, owing to TRIF- and caspase-8-dependent cleavage of N4BP1. Notably, the impaired production of cytokines in response to TLR3 and TLR4 stimulation of caspase-8-deficient macrophages13 was largely rescued by co-deletion of N4BP1. Thus, the persistence of intact N4BP1 in caspase-8-deficient macrophages impairs their ability to mount robust cytokine responses. Tumour necrosis factor (TNF), like TLR3 or TLR4 agonists, also induced caspase-8-dependent cleavage of N4BP1, thereby licensing TRIF-independent TLRs to produce higher levels of inflammatory cytokines. Collectively, our results identify N4BP1 as a potent suppressor of cytokine responses; reveal N4BP1 cleavage by caspase-8 as a point of signal integration during inflammation; and offer an explanation for immunodeficiency caused by mutations of FADD and caspase-8.
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MHC Class I Downregulation in Cancer: Underlying Mechanisms and Potential Targets for Cancer Immunotherapy. Cancers (Basel) 2020; 12:cancers12071760. [PMID: 32630675 PMCID: PMC7409324 DOI: 10.3390/cancers12071760] [Citation(s) in RCA: 213] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/29/2020] [Accepted: 06/29/2020] [Indexed: 12/18/2022] Open
Abstract
In recent years, major advances have been made in cancer immunotherapy. This has led to significant improvement in prognosis of cancer patients, especially in the hematological setting. Nonetheless, translation of these successes to solid tumors was found difficult. One major mechanism through which solid tumors can avoid anti-tumor immunity is the downregulation of major histocompatibility complex class I (MHC-I), which causes reduced recognition by- and cytotoxicity of CD8+ T-cells. Downregulation of MHC-I has been described in 40-90% of human tumors, often correlating with worse prognosis. Epigenetic and (post-)transcriptional dysregulations relevant in the stabilization of NFkB, IRFs, and NLRC5 are often responsible for MHC-I downregulation in cancer. The intrinsic reversible nature of these dysregulations provides an opportunity to restore MHC-I expression and facilitate adaptive anti-tumor immunity. In this review, we provide an overview of the mechanisms underlying reversible MHC-I downregulation and describe potential strategies to counteract this reduction in MHC-I antigen presentation in cancer.
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Santonico E. Old and New Concepts in Ubiquitin and NEDD8 Recognition. Biomolecules 2020; 10:biom10040566. [PMID: 32272761 PMCID: PMC7226360 DOI: 10.3390/biom10040566] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 03/26/2020] [Accepted: 03/27/2020] [Indexed: 12/16/2022] Open
Abstract
Post-translational modifications by ubiquitin and ubiquitin-like proteins (Ubls) have known roles in a myriad of cellular processes. Ubiquitin- and Ubl-binding domains transmit the information conferred by these post-translational modifications by recognizing functional surfaces and, when present, different chain structures. Numerous domains binding to ubiquitin have been characterized and their structures solved. Analogously, motifs selectively interacting with SUMO (small ubiquitin-like modifier) have been identified in several proteins and their role in SUMO-dependent processes investigated. On the other hand, proteins that specifically recognize other Ubl modifications are known only in a few cases. The high sequence identity between NEDD8 and ubiquitin has made the identification of specific NEDD8-binding domains further complicated due to the promiscuity in the recognition by several ubiquitin-binding domains. Two evolutionarily related domains, called CUBAN (cullin-binding domain associating with NEDD8) and CoCUN (cousin of CUBAN), have been recently described. The CUBAN binds monomeric NEDD8 and neddylated cullins, but it also interacts with di-ubiquitin chains. Conversely, the CoCUN domain only binds ubiquitin. CUBAN and CoCUN provide an intriguing example of how nature solved the issue of promiscuity versus selectivity in the recognition of these two highly related molecules. The structural information available to date suggests that the ancestor of CUBAN and CoCUN was a three-helix bundle domain that diversified in KHNYN (KH and NYN domain-containing) and N4BP1 (NEDD4-binding protein-1) by acquiring different features. Indeed, these domains diverged towards two recognition modes, that recall respectively the electrostatic interaction utilized by the E3-ligase RBX1/2 in the interaction with NEDD8, and the hydrophobic features described in the recognition of ubiquitin by CUE (coupling ubiquitin conjugation to ER degradation) domains. Intriguingly, CUBAN and CoCUN domains are only found in KHNYN and N4BP1, respectively, both proteins belonging to the PRORP family whose members are characterized by the combination of protein modules involved in RNA metabolism with domains mediating ubiquitin/NEDD8 recognition. This review recapitulates the current knowledge and recent findings of CUBAN and CoCUN domains and the proteins containing them.
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Affiliation(s)
- Elena Santonico
- Department of Biology, University of Rome Tor Vergata, Via della ricerca scientifica, 00133 Rome, Italy
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The 'dark matter' of ubiquitin-mediated processes: opportunities and challenges in the identification of ubiquitin-binding domains. Biochem Soc Trans 2020; 47:1949-1962. [PMID: 31829417 DOI: 10.1042/bst20190869] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/05/2019] [Accepted: 11/28/2019] [Indexed: 12/19/2022]
Abstract
Ubiquitin modifications of target proteins act to localise, direct and specify a diverse range of cellular processes, many of which are biomedically relevant. To allow this diversity, ubiquitin modifications exhibit remarkable complexity, determined by a combination of polyubiquitin chain length, linkage type, numbers of ubiquitin chains per target, and decoration of ubiquitin with other small modifiers. However, many questions remain about how different ubiquitin signals are specifically recognised and transduced by the decoding ubiquitin-binding domains (UBDs) within ubiquitin-binding proteins. This review briefly outlines our current knowledge surrounding the diversity of UBDs, identifies key challenges in their discovery and considers recent structural studies with implications for the increasing complexity of UBD function and identification. Given the comparatively low numbers of functionally characterised polyubiquitin-selective UBDs relative to the ever-expanding variety of polyubiquitin modifications, it is possible that many UBDs have been overlooked, in part due to limitations of current approaches used to predict their presence within the proteome. Potential experimental approaches for UBD discovery are considered; web-based informatic analyses, Next-Generation Phage Display, deubiquitinase-resistant diubiquitin, proximity-dependent biotinylation and Ubiquitin-Phototrap, including possible advantages and limitations. The concepts discussed here work towards identifying new UBDs which may represent the 'dark matter' of the ubiquitin system.
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Erratum: Nepravishta, R., et al. CoCUN, a Novel Ubiquitin Binding Domain Identified in N4BP1. Biomolecules 2019, 9, 284. Biomolecules 2019; 9:biom9120803. [DOI: 10.3390/biom9120803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 11/26/2019] [Indexed: 11/17/2022] Open
Abstract
The Biomolecules Editorial Offices wishes to make the following erratum to this paper [...]
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