1
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Düring J, Wolter M, Toplak JJ, Torres C, Dybkov O, Fokkens TJ, Bohnsack KE, Urlaub H, Steinchen W, Dienemann C, Lorenz S. Structural mechanisms of autoinhibition and substrate recognition by the ubiquitin ligase HACE1. Nat Struct Mol Biol 2024; 31:364-377. [PMID: 38332367 PMCID: PMC10873202 DOI: 10.1038/s41594-023-01203-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/07/2023] [Indexed: 02/10/2024]
Abstract
Ubiquitin ligases (E3s) are pivotal specificity determinants in the ubiquitin system by selecting substrates and decorating them with distinct ubiquitin signals. However, structure determination of the underlying, specific E3-substrate complexes has proven challenging owing to their transient nature. In particular, it is incompletely understood how members of the catalytic cysteine-driven class of HECT-type ligases (HECTs) position substrate proteins for modification. Here, we report a cryogenic electron microscopy (cryo-EM) structure of the full-length human HECT HACE1, along with solution-based conformational analyses by small-angle X-ray scattering and hydrogen-deuterium exchange mass spectrometry. Structure-based functional analyses in vitro and in cells reveal that the activity of HACE1 is stringently regulated by dimerization-induced autoinhibition. The inhibition occurs at the first step of the catalytic cycle and is thus substrate-independent. We use mechanism-based chemical crosslinking to reconstitute a complex of activated, monomeric HACE1 with its major substrate, RAC1, determine its structure by cryo-EM and validate the binding mode by solution-based analyses. Our findings explain how HACE1 achieves selectivity in ubiquitinating the active, GTP-loaded state of RAC1 and establish a framework for interpreting mutational alterations of the HACE1-RAC1 interplay in disease. More broadly, this work illuminates central unexplored aspects in the architecture, conformational dynamics, regulation and specificity of full-length HECTs.
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Affiliation(s)
- Jonas Düring
- Research Group 'Ubiquitin Signaling Specificity', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Madita Wolter
- Research Group 'Ubiquitin Signaling Specificity', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Julia J Toplak
- Research Group 'Ubiquitin Signaling Specificity', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Camilo Torres
- Research Group 'Ubiquitin Signaling Specificity', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Olexandr Dybkov
- Research Group 'Bioanalytical Mass Spectrometry', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Thornton J Fokkens
- Research Group 'Ubiquitin Signaling Specificity', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Henning Urlaub
- Research Group 'Bioanalytical Mass Spectrometry', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 'Bioanalytics', Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
- 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells', University of Göttingen, Göttingen, Germany
| | - Wieland Steinchen
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
- Center for Synthetic Microbiology, Philipps University Marburg, Marburg, Germany
| | - Christian Dienemann
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Sonja Lorenz
- Research Group 'Ubiquitin Signaling Specificity', Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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2
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Hernández González JE, de Araujo AS. Alchemical Calculation of Relative Free Energies for Charge-Changing Mutations at Protein-Protein Interfaces Considering Fixed and Variable Protonation States. J Chem Inf Model 2023; 63:6807-6822. [PMID: 37851531 DOI: 10.1021/acs.jcim.3c00972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
The calculation of relative free energies (ΔΔG) for charge-changing mutations at protein-protein interfaces through alchemical methods remains challenging due to variations in the system's net charge during charging steps, the possibility of mutated and contacting ionizable residues occurring in various protonation states, and undersampling issues. In this study, we present a set of strategies, collectively termed TIRST/TIRST-H+, to address some of these challenges. Our approaches combine thermodynamic integration (TI) with the prediction of pKa shifts to calculate ΔΔG values. Moreover, special sets of restraints are employed to keep the alchemically transformed molecules separated. The accuracy of the devised approaches was assessed on a large and diverse data set comprising 164 point mutations of charged residues (Asp, Glu, Lys, and Arg) to Ala at the protein-protein interfaces of complexes with known three-dimensional structures. Mean absolute and root-mean-square errors ranging from 1.38 to 1.66 and 1.89 to 2.44 kcal/mol, respectively, and Pearson correlation coefficients of ∼0.6 were obtained when testing the approaches on the selected data set using the GPU-TI module of Amber18 suite and the ff14SB force field. Furthermore, the inclusion of variable protonation states for the mutated acid residues improved the accuracy of the predicted ΔΔG values. Therefore, our results validate the use of TIRST/TIRST-H+ in prospective studies aimed at evaluating the impact of charge-changing mutations to Ala on the stability of protein-protein complexes.
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3
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Chaudhary P, Proulx J, Park IW. Ubiquitin-protein ligase E3A (UBE3A) mediation of viral infection and human diseases. Virus Res 2023; 335:199191. [PMID: 37541588 PMCID: PMC10430597 DOI: 10.1016/j.virusres.2023.199191] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/06/2023]
Abstract
The Ubiquitin-protein ligase E3A, UBE3A, also known as E6-associated protein (E6-AP), is known to play an essential role in regulating the degradation of various proteins by transferring Ub from E2 Ub conjugating enzymes to the substrate proteins. Several studies indicate that UBE3A regulates the stabilities of key viral proteins in the virus-infected cells and, thereby, the infected virus-mediated diseases, even if it were reported that UBE3A participates in non-viral-related human diseases. Furthermore, mutations such as deletions and duplications in the maternally inherited gene in the brain cause human neurodevelopmental disorders such as Angelman syndrome (AS) and autism. It is also known that UBE3A functions as a transcriptional coactivator for the expression of steroid hormone receptors. These reports establish that UBE3A is distinguished by its multitudinous functions that are paramount to viral pathology and human diseases. This review is focused on molecular mechanisms for such intensive participation of UBE3A in disease formation and virus regulation.
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Affiliation(s)
- Pankaj Chaudhary
- Department of Microbiology, Immunology and Genetics, School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, United States.
| | - Jessica Proulx
- Department of Microbiology, Immunology and Genetics, School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, United States
| | - In-Woo Park
- Department of Microbiology, Immunology and Genetics, School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, United States.
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4
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Lin Z, Nie H, Zhang Y, Yin Z, Yan X. Genome-wide identification and analysis of HECT E3 ubiquitin ligase gene family in Ruditapes philippinarum and their involvement in the response to heat stress and Vibrio anguillarum infection. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2022; 43:101012. [PMID: 35849989 DOI: 10.1016/j.cbd.2022.101012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/06/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
E3 ubiquitin ligase (E3s) plays an important role in ubiquitin proteasome pathway, proteins containing homologous E6-AP carboxyl terminus (HECT) domains. However, the role of HECT E3 ubiquitin ligase in mollusk was rarely explored. In this study, we performed a genome-wide analysis of the HECT domain-containing gene in Ruditapes philippinarum to identify and predict the structural and functional characterization of HECT genes in response to abiotic and biotic stress. A total of sixteen members of HECT gene family were identified and analyzed for the gene structure, phylogenetic relation, three-dimensional structure, protein interaction network, and expression patterns. Experimental results demonstrated that Rph.HUWE1, Rph.HECTD1, Rph.Ubr5 were significantly up-regulated in response to heat stress and bacterial challenge. Taken together, our data provide insights into the potential function of HECT E3 ligase in heat stress and Vibrio anguillarum infection.
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Affiliation(s)
- Zihan Lin
- Engineering and Technology Research Center of Shellfish Breeding in Liaoning Province, College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China
| | - Hongtao Nie
- Engineering and Technology Research Center of Shellfish Breeding in Liaoning Province, College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China.
| | - Yanming Zhang
- Engineering and Technology Research Center of Shellfish Breeding in Liaoning Province, College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China
| | - Zhihui Yin
- Engineering and Technology Research Center of Shellfish Breeding in Liaoning Province, College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China
| | - Xiwu Yan
- Engineering and Technology Research Center of Shellfish Breeding in Liaoning Province, College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China
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5
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Zhang X, Huo C, Liu Y, Su R, Zhao Y, Li Y. Mechanism and Disease Association With a Ubiquitin Conjugating E2 Enzyme: UBE2L3. Front Immunol 2022; 13:793610. [PMID: 35265070 PMCID: PMC8899012 DOI: 10.3389/fimmu.2022.793610] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 01/24/2022] [Indexed: 12/12/2022] Open
Abstract
Ubiquitin conjugating enzyme E2 is an important component of the post-translational protein ubiquitination pathway, which mediates the transfer of activated ubiquitin to substrate proteins. UBE2L3, also called UBcH7, is one of many E2 ubiquitin conjugating enzymes that participate in the ubiquitination of many substrate proteins and regulate many signaling pathways, such as the NF-κB, GSK3β/p65, and DSB repair pathways. Studies on UBE2L3 have found that it has an abnormal expression in many diseases, mainly immune diseases, tumors and Parkinson’s disease. It can also promote the occurrence and development of these diseases. Resultantly, UBE2L3 may become an important target for some diseases. Herein, we review the structure of UBE2L3, and its mechanism in diseases, as well as diseases related to UBE2L3 and discuss the related challenges.
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Affiliation(s)
- Xiaoxia Zhang
- Department of Ophthalmology, Lanzhou University Second Hospital, Lanzhou, China.,Key Laboratory of the Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, China
| | - Chengdong Huo
- Department of Ophthalmology, Lanzhou University Second Hospital, Lanzhou, China.,Key Laboratory of the Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, China
| | - Yating Liu
- Key Laboratory of the Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, China
| | - Ruiliang Su
- Key Laboratory of the Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, China
| | - Yang Zhao
- Key Laboratory of the Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, China
| | - Yumin Li
- Key Laboratory of the Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, China
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6
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Weston KP, Gao X, Zhao J, Kim KS, Maloney SE, Gotoff J, Parikh S, Leu YC, Wu KP, Shinawi M, Steimel JP, Harrison JS, Yi JJ. Identification of disease-linked hyperactivating mutations in UBE3A through large-scale functional variant analysis. Nat Commun 2021; 12:6809. [PMID: 34815418 PMCID: PMC8635412 DOI: 10.1038/s41467-021-27156-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 11/01/2021] [Indexed: 12/03/2022] Open
Abstract
The mechanisms that underlie the extensive phenotypic diversity in genetic disorders are poorly understood. Here, we develop a large-scale assay to characterize the functional valence (gain or loss-of-function) of missense variants identified in UBE3A, the gene whose loss-of-function causes the neurodevelopmental disorder Angelman syndrome. We identify numerous gain-of-function variants including a hyperactivating Q588E mutation that strikingly increases UBE3A activity above wild-type UBE3A levels. Mice carrying the Q588E mutation exhibit aberrant early-life motor and communication deficits, and individuals possessing hyperactivating UBE3A variants exhibit affected phenotypes that are distinguishable from Angelman syndrome. Additional structure-function analysis reveals that Q588 forms a regulatory site in UBE3A that is conserved among HECT domain ubiquitin ligases and perturbed in various neurodevelopmental disorders. Together, our study indicates that excessive UBE3A activity increases the risk for neurodevelopmental pathology and suggests that functional variant analysis can help delineate mechanistic subtypes in monogenic disorders. UBE3A gene dysregulation is associated with neurodevelopmental disorders, but predicting the function of UBE3A variants remains difficult. The authors use a high-throughput assay to categorize variants by functional activity, and show that UBE3A hyperactivity increases the risk of neurodevelopmental disease.
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Affiliation(s)
- Kellan P Weston
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Xiaoyi Gao
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jinghan Zhao
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Kwang-Soo Kim
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Susan E Maloney
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jill Gotoff
- Department of Pediatrics, Geisinger Medical Center, Danville, PA, 17822, USA
| | - Sumit Parikh
- Department of Neurogenetics, Neurosciences Institute, Cleveland Clinic, Cleveland, OH, 44106, USA
| | - Yen-Chen Leu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Kuen-Phon Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Joshua P Steimel
- Deparment of Mechanical Engineering, University of the Pacific, Stockton, CA, 95211, USA
| | - Joseph S Harrison
- Department of Chemistry, University of the Pacific, Stockton, CA, 95211, USA
| | - Jason J Yi
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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7
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Singh S, Ng J, Sivaraman J. Exploring the "Other" subfamily of HECT E3-ligases for therapeutic intervention. Pharmacol Ther 2021; 224:107809. [PMID: 33607149 DOI: 10.1016/j.pharmthera.2021.107809] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/13/2020] [Accepted: 01/26/2021] [Indexed: 12/14/2022]
Abstract
The HECT E3 ligase family regulates key cellular signaling pathways, with its 28 members divided into three subfamilies: NEDD4 subfamily (9 members), HERC subfamily (6 members) and "Other" subfamily (13 members). Here, we focus on the less-explored "Other" subfamily and discuss the recent findings pertaining to their biological roles. The N-terminal regions preceding the conserved HECT domains are significantly diverse in length and sequence composition, and are mostly unstructured, except for short regions that incorporate known substrate-binding domains. In some of the better-characterized "Other" members (e.g., HUWE1, AREL1 and UBE3C), structure analysis shows that the extended region (~ aa 50) adjacent to the HECT domain affects the stability and activity of the protein. The enzymatic activity is also influenced by interactions with different adaptor proteins and inter/intramolecular interactions. Primarily, the "Other" subfamily members assemble atypical ubiquitin linkages, with some cooperating with E3 ligases from the other subfamilies to form branched ubiquitin chains on substrates. Viruses and pathogenic bacteria target and hijack the activities of "Other" subfamily members to evade host immune responses and cause diseases. As such, these HECT E3 ligases have emerged as potential candidates for therapeutic drug development.
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Affiliation(s)
- Sunil Singh
- Department of Biological Sciences, 14 Science Drive 4, National University of Singapore, 117543, Singapore
| | - Joel Ng
- Department of Biological Sciences, 14 Science Drive 4, National University of Singapore, 117543, Singapore
| | - J Sivaraman
- Department of Biological Sciences, 14 Science Drive 4, National University of Singapore, 117543, Singapore.
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8
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You X, Zhang Y, Long Q, Liu Z, Feng Z, Zhang W, Teng Z, Zeng Y. Does single gene expression omnibus data mining analysis apply for only tumors and not mental illness? A preliminary study on bipolar disorder based on bioinformatics methodology. Medicine (Baltimore) 2020; 99:e21989. [PMID: 32871949 PMCID: PMC7458177 DOI: 10.1097/md.0000000000021989] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Bipolar disorder (BD), a common kind of mood disorder with frequent recurrence, high rates of additional comorbid conditions and poor compliance, has an unclear pathogenesis. The Gene Expression Omnibus (GEO) database is a gene expression database created and maintained by the National Center for Biotechnology Information. Researchers can download expression data online for bioinformatics analysis, especially for cancer research. However, there is little research on the use of such bioinformatics analysis methodologies for mental illness by downloading differential expression data from the GEO database. METHODS Publicly available data were downloaded from the GEO database (GSE12649, GSE5388 and GSE5389), and differentially expressed genes (DEGs) were extracted by using the online tool GEO2R. A Venn diagram was used to screen out common DEGs between postmortem brain tissues and normal tissues. Functional annotation and pathway enrichment analysis of DEGs were performed by using Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses, respectively. Furthermore, a protein-protein interaction network was constructed to identify hub genes. RESULTS A total of 289 DEGs were found, among which 5 of 10 hub genes [HSP90AA1, HSP90AB 1, UBE2N, UBE3A, and CUL1] were identified as susceptibility genes whose expression was downregulated. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that variations in these 5 hub genes were obviously enriched in protein folding, protein polyubiquitination, apoptotic process, protein binding, the ubiquitin-mediated proteolysis pathway, and protein processing in the endoplasmic reticulum pathway. These findings strongly suggested that HSP90AA1, UBE3A, and CUL 1, which had large areas under the curve in receiver operator curves (P < .05), were potential diagnostic markers for BD. CONCLUSION Although there are 3 hub genes [HSP90AA1, UBE3A, and CUL 1] that are tightly correlated with the occurrence of BD, mainly based on routine bioinformatics methods for cancer-related disease, the feasibility of applying this single GEO bioinformatics approach for mental illness is questionable, given the significant differences between mental illness and cancer-related diseases.
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9
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Musaus M, Navabpour S, Jarome TJ. The diversity of linkage-specific polyubiquitin chains and their role in synaptic plasticity and memory formation. Neurobiol Learn Mem 2020; 174:107286. [PMID: 32745599 DOI: 10.1016/j.nlm.2020.107286] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/15/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022]
Abstract
Over the last 20 years, a number of studies have provided strong support for protein degradation mediated by the ubiquitin-proteasome system in synaptic plasticity and memory formation. In this system, target substrates become covalently modified by the small protein ubiquitin through a series of enzymatic reactions involving hundreds of different ligases. While some substrates will acquire only a single ubiquitin, most will be marked by multiple ubiquitin modifications, which link together at specific lysine sites or the N-terminal methionine on the previous ubiquitin to form a polyubiquitin chain. There are at least eight known linkage-specific polyubiquitin chains a target protein can acquire, many of which are independent of the proteasome, and these chains can be homogenous, mixed, or branched in nature, all of which result in different functional outcomes and fates for the target substrate. However, as the focus has remained on protein degradation, much remains unknown about the role of these diverse ubiquitin chains in the brain, particularly during activity- and learning-dependent synaptic plasticity. Here, we review the different types and functions of ubiquitin chains and summarize evidence suggesting a role for these diverse ubiquitin modifications in synaptic plasticity and memory formation. We conclude by discussing how technological limitations have limited our ability to identify and elucidate the role of different ubiquitin chains in the brain and speculate on the future directions and implications of understanding linkage-specific ubiquitin modifications in activity- and learning-dependent synaptic plasticity.
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Affiliation(s)
- Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shaghayegh Navabpour
- Fralin Biomedical Research Institute, Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - Timothy J Jarome
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; Fralin Biomedical Research Institute, Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA; Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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10
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Lopez SJ, Laufer BI, Beitnere U, Berg EL, Silverman JL, O'Geen H, Segal DJ, LaSalle JM. Imprinting effects of UBE3A loss on synaptic gene networks and Wnt signaling pathways. Hum Mol Genet 2020; 28:3842-3852. [PMID: 31625566 DOI: 10.1093/hmg/ddz221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/21/2019] [Accepted: 09/04/2019] [Indexed: 12/13/2022] Open
Abstract
Ubiquitin E3 ligase 3A (UBE3A) encodes an E3 ubiquitin ligase whose loss from the maternal allele causes the neurodevelopmental disorder Angelman syndrome (AS). Previous studies of UBE3A function have not examined full Ube3a deletion in mouse, the complexity of imprinted gene networks in brain nor the molecular basis of systems-level cognitive dysfunctions in AS. We therefore utilized a systems biology approach to elucidate how UBE3A loss impacts the early postnatal brain in a novel CRISPR/Cas9-engineered rat Angelman model of a complete Ube3a deletion. Strand-specific transcriptome analysis of offspring from maternally or paternally inherited Ube3a deletions revealed the expected parental expression patterns of Ube3a sense and antisense transcripts by postnatal day 2 (P2) in hypothalamus and day 9 (P9) in cortex, compared to wild-type littermates. The dependency of genome-wide effects on parent-of-origin, Ube3a genotype and time (P2 and P9) was investigated through transcriptome (RNA sequencing of cortex and hypothalamus) and methylome (whole-genome bisulfite sequencing of hypothalamus). Weighted gene co-expression and co-methylation network analyses identified co-regulated networks in maternally inherited Ube3a deletion offspring enriched in postnatal developmental processes including Wnt signaling, synaptic regulation, neuronal and glial functions, epigenetic regulation, ubiquitin, circadian entrainment and splicing. Furthermore, we showed that loss of the paternal Ube3a antisense transcript resulted in both unique and overlapping dysregulated gene pathways with maternal loss, predominantly at the level of differential methylation. Together, these results provide a holistic examination of the molecular impacts of UBE3A loss in brain, supporting the existence of interactive epigenetic networks between maternal and paternal transcripts at the Ube3a locus.
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Affiliation(s)
- S Jesse Lopez
- Medical Immunology and Microbiology, University of California (UC) Davis School of Medicine, Davis, CA 95616, USA.,Genome Center, UC Davis, Davis, CA, USA.,Integrative Genetics and Genomics, UC Davis, Davis, CA 95616, USA.,Biochemistry and Molecular Medicine, UC Davis School of Medicine, Davis, CA 95616, USA.,Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA
| | - Benjamin I Laufer
- Medical Immunology and Microbiology, University of California (UC) Davis School of Medicine, Davis, CA 95616, USA.,Genome Center, UC Davis, Davis, CA, USA.,Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA
| | - Ulrika Beitnere
- Genome Center, UC Davis, Davis, CA, USA.,Biochemistry and Molecular Medicine, UC Davis School of Medicine, Davis, CA 95616, USA.,Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA
| | - Elizabeth L Berg
- Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA.,Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacromento, CA 95817, USA
| | - Jill L Silverman
- Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA.,Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacromento, CA 95817, USA
| | - Henriette O'Geen
- Genome Center, UC Davis, Davis, CA, USA.,Biochemistry and Molecular Medicine, UC Davis School of Medicine, Davis, CA 95616, USA.,Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA
| | - David J Segal
- Genome Center, UC Davis, Davis, CA, USA.,Integrative Genetics and Genomics, UC Davis, Davis, CA 95616, USA.,Biochemistry and Molecular Medicine, UC Davis School of Medicine, Davis, CA 95616, USA.,Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA
| | - Janine M LaSalle
- Medical Immunology and Microbiology, University of California (UC) Davis School of Medicine, Davis, CA 95616, USA.,Genome Center, UC Davis, Davis, CA, USA.,Integrative Genetics and Genomics, UC Davis, Davis, CA 95616, USA.,Medical Investigation of Neurodevelopmental Disorders Institute, UC Davis Health, Sacramento, CA 95817, USA
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11
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Masuda Y, Saeki Y, Arai N, Kawai H, Kukimoto I, Tanaka K, Masutani C. Stepwise multipolyubiquitination of p53 by the E6AP-E6 ubiquitin ligase complex. J Biol Chem 2019; 294:14860-14875. [PMID: 31492752 DOI: 10.1074/jbc.ra119.008374] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 08/13/2019] [Indexed: 01/01/2023] Open
Abstract
The human papillomavirus (HPV) oncoprotein E6 specifically binds to E6AP (E6-associated protein), a HECT (homologous to the E6AP C terminus)-type ubiquitin ligase, and directs its ligase activity toward the tumor suppressor p53. To examine the biochemical reaction in vitro, we established an efficient reconstitution system for the polyubiquitination of p53 by the E6AP-E6 complex. We demonstrate that E6AP-E6 formed a stable ternary complex with p53, which underwent extensive polyubiquitination when the isolated ternary complex was incubated with E1, E2, and ubiquitin. Mass spectrometry and biochemical analysis of the reaction products identified lysine residues as p53 ubiquitination sites. A p53 mutant with arginine substitutions of its 18 lysine residues was not ubiquitinated. Analysis of additional p53 mutants retaining only one or two intact ubiquitination sites revealed that chain elongation at each of these sites was limited to 5-6-mers. We also determined the size distribution of ubiquitin chains released by en bloc cleavage from polyubiquitinated p53 to be 2-6-mers. Taken together, these results strongly suggest that p53 is multipolyubiquitinated with short chains by E6AP-E6. In addition, analysis of growing chains provided strong evidence for step-by-step chain elongation. Thus, we hypothesize that p53 is polyubiquitinated in a stepwise manner through the back-and-forth movement of the C-lobe, and the permissive distance for the movement of the C-lobe restricts the length of the chains in the E6AP-E6-p53 ternary complex. Finally, we show that multipolyubiquitination at different sites provides a signal for proteasomal degradation.
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Affiliation(s)
- Yuji Masuda
- Department of Genome Dynamics, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan .,Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yasushi Saeki
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Naoko Arai
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Hidehiko Kawai
- Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Iwao Kukimoto
- Pathogen Genomics Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Keiji Tanaka
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Chikahide Masutani
- Department of Genome Dynamics, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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12
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Using In Vitro Ubiquitylation Assays to Estimate the Affinities of Ubiquitin-Conjugating Enzymes for Their Ubiquitin Ligase Partners. Methods Mol Biol 2019. [PMID: 30242702 DOI: 10.1007/978-1-4939-8706-1_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
Ubiquitin ligases (E3s) function by binding to both a protein substrate and to ubiquitin-conjugating enzymes (E2s) bound to ubiquitin. E3s facilitate the transfer of ubiquitin from the E2 active site to an E3-bound substrate. Thus, the affinity of the interaction of an E2 with its E3 partner is of considerable interest. The purpose of this work is to (1) provide protocols for the purification of the human E2 Cdc34, as well as for some additional protein components needed for the assays described here whose purification protocols haven't been described elsewhere in detail; (2) provide the researcher with critical information regarding the proper long-term storage of these enzymes to retain maximal activity; (3) provide a protocol to benchmark Cdc34 activity with previously described activity levels in the literature; and (4) provide a simple and rapid means of measuring E2 affinity for an E3.
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13
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Ries LK, Sander B, Deol KK, Letzelter MA, Strieter ER, Lorenz S. Analysis of ubiquitin recognition by the HECT ligase E6AP provides insight into its linkage specificity. J Biol Chem 2019; 294:6113-6129. [PMID: 30737286 PMCID: PMC6463701 DOI: 10.1074/jbc.ra118.007014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/28/2019] [Indexed: 12/19/2022] Open
Abstract
Deregulation of the HECT-type ubiquitin ligase E6AP (UBE3A) is implicated in human papilloma virus-induced cervical tumorigenesis and several neurodevelopmental disorders. Yet the structural underpinnings of activity and specificity in this crucial ligase are incompletely understood. Here, we unravel the determinants of ubiquitin recognition by the catalytic domain of E6AP and assign them to particular steps in the catalytic cycle. We identify a functionally critical interface that is specifically required during the initial formation of a thioester-linked intermediate between the C terminus of ubiquitin and the ligase-active site. This interface resembles the one utilized by NEDD4-type enzymes, indicating that it is widely conserved across HECT ligases, independent of their linkage specificities. Moreover, we uncover surface regions in ubiquitin and E6AP, both in the N- and C-terminal portions of the catalytic domain, that are important for the subsequent reaction step of isopeptide bond formation between two ubiquitin molecules. We decipher key elements of linkage specificity, including the C-terminal tail of E6AP and a hydrophilic surface region of ubiquitin in proximity to the acceptor site Lys-48. Intriguingly, mutation of Glu-51, a single residue within this region, permits formation of alternative chain types, thus pointing to a key role of ubiquitin in conferring linkage specificity to E6AP. We speculate that substrate-assisted catalysis, as described previously for certain RING-associated ubiquitin-conjugating enzymes, constitutes a common principle during linkage-specific ubiquitin chain assembly by diverse classes of ubiquitination enzymes, including HECT ligases.
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Affiliation(s)
- Lena K Ries
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Bodo Sander
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Kirandeep K Deol
- Department of Chemistry, University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - Marie-Annick Letzelter
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Eric Robert Strieter
- Department of Chemistry, University of Massachusetts at Amherst, Amherst, Massachusetts 01003; Departments of Biochemistry and Molecular Biology, University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - Sonja Lorenz
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany.
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14
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Turek I, Tischer N, Lassig R, Trujillo M. Multi-tiered pairing selectivity between E2 ubiquitin-conjugating enzymes and E3 ligases. J Biol Chem 2018; 293:16324-16336. [PMID: 30185618 PMCID: PMC6200922 DOI: 10.1074/jbc.ra118.004226] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/03/2018] [Indexed: 12/17/2022] Open
Abstract
Ubiquitination is a prevalent post-translational modification involved in all aspects of cell physiology. It is mediated by an enzymatic cascade and the E2 ubiquitin-conjugating enzymes (UBCs) lie at its heart. Even though E3 ubiquitin ligases determine the specificity of the reaction, E2s catalyze the attachment of ubiquitin and have emerged as key mediators of chain assembly. They are largely responsible for the type of linkage between ubiquitin moieties and thus, the fate endowed onto the modified substrate. However, in vivo E2-E3 pairing remains largely unexplored. We therefore interrogated the interaction selectivity between 37 Arabidopsis E2s and PUB22, a U-box type E3 ubiquitin ligase that is involved in the dampening of immune signaling. We show that whereas the U-box domain, which mediates E2 docking, is able to interact with 18 of 37 tested E2s, the substrate interacting armadillo (ARM) repeats impose a second layer of specificity, allowing the interaction with 11 E2s. In vitro activity assayed by autoubiquitination only partially recapitulated the in vivo selectivity. Moreover, in vivo pairing was modulated during the immune response; pairing with group VI UBC30 was inhibited, whereas interaction with the K63 chain-building UBC35 was increased. Functional analysis of ubc35 ubc36 mutants shows that they partially mimic pub22 pub23 pub24 enhanced activation of immune responses. Together, our work provides a framework to interrogate in vivo E2-E3 pairing and reveals a multi-tiered and dynamic E2-E3 network.
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Affiliation(s)
- Ilona Turek
- From the Leibniz Institute of Plant Biochemistry, Independent Junior Research Group, Weinberg 3, 06120 Halle (Saale) and
| | - Nadine Tischer
- From the Leibniz Institute of Plant Biochemistry, Independent Junior Research Group, Weinberg 3, 06120 Halle (Saale) and
| | - Roman Lassig
- From the Leibniz Institute of Plant Biochemistry, Independent Junior Research Group, Weinberg 3, 06120 Halle (Saale) and
| | - Marco Trujillo
- From the Leibniz Institute of Plant Biochemistry, Independent Junior Research Group, Weinberg 3, 06120 Halle (Saale) and
- the Albert-Ludwigs-University of Freiburg, Faculty of Biology, Institute of Biology II, Cell Biology, Schänzlestrasse 1, 79104 Freiburg, Germany
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15
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Lorenz S. Structural mechanisms of HECT-type ubiquitin ligases. Biol Chem 2018; 399:127-145. [PMID: 29016349 DOI: 10.1515/hsz-2017-0184] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/25/2017] [Indexed: 12/31/2022]
Abstract
Ubiquitin ligases (E3 enzymes) transfer ubiquitin from ubiquitin-conjugating (E2) enzymes to target proteins. By determining the selection of target proteins, modification sites on those target proteins, and the types of ubiquitin modifications that are formed, E3 enzymes are key specificity factors in ubiquitin signaling. Here, I summarize our knowledge of the structural mechanisms in the HECT E3 subfamily, many members of which play important roles in human disease. I discuss interactions of the conserved HECT domain with E2 enzymes, ubiquitin and target proteins, as well as macromolecular interactions with regulatory functions. While we understand individual steps in the catalytic cycle of HECT E3 enzymes on a structural level, this review also highlights key aspects that have yet to be elucidated. For instance, it remains unclear how diverse target proteins are presented to the catalytic center and how certain HECT E3 enzymes achieve specificity in ubiquitin linkage formation. The structural and functional properties of the N-terminal regions of HECT E3 enzymes that likely act as signaling hubs are also largely unknown. Structural insights into these aspects may open up routes for a therapeutic intervention with specific HECT E3 functions in distinct pathophysiological settings.
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Affiliation(s)
- Sonja Lorenz
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
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16
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Perez JM, Chen Y, Xiao TS, Abbott DW. Phosphorylation of the E3 ubiquitin protein ligase ITCH diminishes binding to its cognate E2 ubiquitin ligase. J Biol Chem 2017; 293:1100-1105. [PMID: 29212706 DOI: 10.1074/jbc.ra117.000408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/21/2017] [Indexed: 12/21/2022] Open
Abstract
Heightened and extended inflammation underlies the pathogenesis of many disorders, including inflammatory bowel disease, sepsis, and inflammatory arthritis. Ubiquitin networks help dictate the strength and duration of inflammatory signaling. In innate immunity, the itchy E3 ubiquitin protein ligase (ITCH)-A20 ubiquitin-editing complex inhibits receptor-interacting Ser/Thr kinase (RIPK) activation by removing Lys-63-linked polyubiquitinated chains from key proteins in the nuclear factor kappa B (NF-κB) signaling pathway. The complex then attaches polyubiquitinated chains to these proteins to target them for lysosomal or proteasomal destruction. ITCH is phosphorylated and thereby inhibited by inhibitor of nuclear factor kappa B kinase subunit beta (IKKβ) to fine-tune the inflammatory response to the strength of the offending signal. However, the biochemical mechanism by which E3 ubiquitination is impaired by IKK-driven phosphorylation remains unclear. Here, we report that this phosphorylation impedes ITCH binding to its cognate E2 ubiquitin ligase, UbcH7. Using CRISPR-Cas9 genetic knockout to mimic the ITCH-UbcH7-inhibited state, we further show that genetic UbcH7 deficiency phenocopies ITCH phosphorylation in regulating RIPK2 ubiquitination. We conclude that phosphorylation can disrupt the binding of an E3 ubiquitin ligase to an E2-conjugating enzyme, leading to prolonged inflammatory signaling. To our knowledge, this is the first report of E3 ubiquitin ligase phosphorylation inhibiting E3 ligase activity by impairing E2-E3 complex formation.
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Affiliation(s)
| | - Yinghua Chen
- Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
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17
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Lopez SJ, Dunaway K, Islam MS, Mordaunt C, Vogel Ciernia A, Meguro-Horike M, Horike SI, Segal DJ, LaSalle JM. UBE3A-mediated regulation of imprinted genes and epigenome-wide marks in human neurons. Epigenetics 2017; 12:982-990. [PMID: 28925810 PMCID: PMC5788436 DOI: 10.1080/15592294.2017.1376151] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The dysregulation of genes in neurodevelopmental disorders that lead to social and cognitive phenotypes is a complex, multilayered process involving both genetics and epigenetics. Parent-of-origin effects of deletion and duplication of the 15q11-q13 locus leading to Angelman, Prader-Willi, and Dup15q syndromes are due to imprinted genes, including UBE3A, which is maternally expressed exclusively in neurons. UBE3A encodes a ubiquitin E3 ligase protein with multiple downstream targets, including RING1B, which in turn monoubiquitinates histone variant H2A.Z. To understand the impact of neuronal UBE3A levels on epigenome-wide marks of DNA methylation, histone variant H2A.Z positioning, active H3K4me3 promoter marks, and gene expression, we took a multi-layered genomics approach. We performed an siRNA knockdown of UBE3A in two human neuroblastoma cell lines, including parental SH-SY5Y and the SH(15M) model of Dup15q. Genes differentially methylated across cells with differing UBE3A levels were enriched for functions in gene regulation, DNA binding, and brain morphology. Importantly, we found that altering UBE3A levels had a profound epigenetic effect on the methylation levels of up to half of known imprinted genes. Genes with differential H2A.Z peaks in SH(15M) compared to SH-SY5Y were enriched for ubiquitin and protease functions and associated with autism, hypoactivity, and energy expenditure. Together, these results support a genome-wide epigenetic consequence of altered UBE3A levels in neurons and suggest that UBE3A regulates an imprinted gene network involving DNA methylation patterning and H2A.Z deposition.
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Affiliation(s)
- S Jesse Lopez
- a Medical Immunology and Microbiology , University of California , Davis , CA , USA.,b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA.,d Integrative Genetics and Genomics , University of California , Davis , CA , USA
| | - Keith Dunaway
- a Medical Immunology and Microbiology , University of California , Davis , CA , USA.,b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA.,d Integrative Genetics and Genomics , University of California , Davis , CA , USA
| | - M Saharul Islam
- a Medical Immunology and Microbiology , University of California , Davis , CA , USA.,b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA
| | - Charles Mordaunt
- a Medical Immunology and Microbiology , University of California , Davis , CA , USA.,b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA
| | - Annie Vogel Ciernia
- a Medical Immunology and Microbiology , University of California , Davis , CA , USA.,b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA
| | - Makiko Meguro-Horike
- f Advanced Science Research Center , Kanazawa University , 13-1 Takaramachi, Kanazawa , Ishikawa , Japan
| | - Shin-Ichi Horike
- f Advanced Science Research Center , Kanazawa University , 13-1 Takaramachi, Kanazawa , Ishikawa , Japan
| | - David J Segal
- b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA.,d Integrative Genetics and Genomics , University of California , Davis , CA , USA.,e Biochemistry and Molecular Medicine , University of California , Davis , CA , USA
| | - Janine M LaSalle
- a Medical Immunology and Microbiology , University of California , Davis , CA , USA.,b Genome Center , University of California , Davis , CA , USA.,c MIND Institute, University of California , Davis , CA , USA.,d Integrative Genetics and Genomics , University of California , Davis , CA , USA
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18
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Todaro DR, Augustus-Wallace AC, Klein JM, Haas AL. The mechanism of neural precursor cell expressed developmentally down-regulated 4-2 (Nedd4-2)/NEDD4L-catalyzed polyubiquitin chain assembly. J Biol Chem 2017; 292:19521-19536. [PMID: 28972136 DOI: 10.1074/jbc.m117.817882] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Indexed: 11/06/2022] Open
Abstract
The mechanism of Nedd4-2 has been quantitatively explored for the first time using biochemically defined kinetic assays examining rates of 125I-polyubiquitin chain assembly as a functional readout. We demonstrate that Nedd4-2 exhibits broad specificity for E2 paralogs of the Ubc4/5 clade to assemble Lys63-linked polyubiquitin chains. Full-length Nedd4-2 catalyzes free 125I-polyubiquitin chain assembly by hyperbolic Michaelis-Menten kinetics with respect to Ubc5B∼ubiquitin thioester concentration (Km = 44 ± 6 nm; kcat = 0.020 ± 0.007 s-1) and substrate inhibition above 0.5 μm (Ki = 2.5 ± 1.3 μm) that tends to zero velocity, requiring ordered binding at two functionally distinct E2∼ubiquitin-binding sites. The Ubc5BC85A product analog non-competitively inhibits Nedd4-2 (Ki = 2.0 ± 0.5 μm), consistent with the presence of the second E2-binding site. In contrast, the isosteric Ubc5BC85S-ubiquitin oxyester substrate analog exhibits competitive inhibition at the high-affinity Site 1 (Ki = 720 ± 340 nm) and non-essential activation at the lower-affinity Site 2 (Kact = 750 ± 260 nm). Additional studies utilizing Ubc5BF62A, defective in binding the canonical E2 site, demonstrate that the cryptic Site 1 is associated with thioester formation, whereas binding at the canonical site (Site 2) is associated with polyubiquitin chain elongation. Finally, previously described Ca2+-dependent C2 domain-mediated autoinhibition of Nedd4-2 is not observed under our reported experimental conditions. These studies collectively demonstrate that Nedd4-2 catalyzes polyubiquitin chain assembly by an ordered two-step mechanism requiring two dynamically linked E2∼ubiquitin-binding sites analogous to that recently reported for E6AP, the founding member of the Hect ligase family.
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Affiliation(s)
- Dustin R Todaro
- From the Department of Biochemistry and Molecular Biology and
| | | | | | - Arthur L Haas
- From the Department of Biochemistry and Molecular Biology and .,the Stanley S. Scott Cancer Center, Louisiana State University School of Medicine, New Orleans, Louisiana 70112
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19
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Ronchi VP, Kim ED, Summa CM, Klein JM, Haas AL. In silico modeling of the cryptic E2∼ubiquitin-binding site of E6-associated protein (E6AP)/UBE3A reveals the mechanism of polyubiquitin chain assembly. J Biol Chem 2017; 292:18006-18023. [PMID: 28924046 DOI: 10.1074/jbc.m117.813477] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Indexed: 12/13/2022] Open
Abstract
To understand the mechanism for assembly of Lys48-linked polyubiquitin degradation signals, we previously demonstrated that the E6AP/UBE3A ligase harbors two functionally distinct E2∼ubiquitin-binding sites: a high-affinity Site 1 required for E6AP Cys820∼ubiquitin thioester formation and a canonical Site 2 responsible for subsequent chain elongation. Ordered binding to Sites 1 and 2 is here revealed by observation of UbcH7∼ubiquitin-dependent substrate inhibition of chain formation at micromolar concentrations. To understand substrate inhibition, we exploited the PatchDock algorithm to model in silico UbcH7∼ubiquitin bound to Site 1, validated by chain assembly kinetics of selected point mutants. The predicted structure buries an extensive solvent-excluded surface bringing the UbcH7∼ubiquitin thioester bond within 6 Å of the Cys820 nucleophile. Modeling onto the active E6AP trimer suggests that substrate inhibition arises from steric hindrance between Sites 1 and 2 of adjacent subunits. Confirmation that Sites 1 and 2 function in trans was demonstrated by examining the effect of E6APC820A on wild-type activity and single-turnover pulse-chase kinetics. A cyclic proximal indexation model proposes that Sites 1 and 2 function in tandem to assemble thioester-linked polyubiquitin chains from the proximal end attached to Cys820 before stochastic en bloc transfer to the target protein. Non-reducing SDS-PAGE confirms assembly of the predicted Cys820-linked 125I-polyubiquitin thioester intermediate. Other studies suggest that Glu550 serves as a general base to generate the Cys820 thiolate within the low dielectric binding interface and Arg506 functions to orient Glu550 and to stabilize the incipient anionic transition state during thioester exchange.
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Affiliation(s)
| | - Elizabeth D Kim
- From the Department of Biochemistry and Molecular Biology and
| | - Christopher M Summa
- the Department of Computer Science, University of New Orleans, New Orleans, Louisiana 70148
| | | | - Arthur L Haas
- From the Department of Biochemistry and Molecular Biology and .,the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112 and
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20
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Mechanism and disease association of E2-conjugating enzymes: lessons from UBE2T and UBE2L3. Biochem J 2017; 473:3401-3419. [PMID: 27729585 PMCID: PMC5095918 DOI: 10.1042/bcj20160028] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 08/09/2016] [Indexed: 02/07/2023]
Abstract
Ubiquitin signalling is a fundamental eukaryotic regulatory system, controlling diverse cellular functions. A cascade of E1, E2, and E3 enzymes is required for assembly of distinct signals, whereas an array of deubiquitinases and ubiquitin-binding modules edit, remove, and translate the signals. In the centre of this cascade sits the E2-conjugating enzyme, relaying activated ubiquitin from the E1 activating enzyme to the substrate, usually via an E3 ubiquitin ligase. Many disease states are associated with dysfunction of ubiquitin signalling, with the E3s being a particular focus. However, recent evidence demonstrates that mutations or impairment of the E2s can lead to severe disease states, including chromosome instability syndromes, cancer predisposition, and immunological disorders. Given their relevance to diseases, E2s may represent an important class of therapeutic targets. In the present study, we review the current understanding of the mechanism of this important family of enzymes, and the role of selected E2s in disease.
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21
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Sander B, Xu W, Eilers M, Popov N, Lorenz S. A conformational switch regulates the ubiquitin ligase HUWE1. eLife 2017; 6:e21036. [PMID: 28193319 PMCID: PMC5308896 DOI: 10.7554/elife.21036] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 01/27/2017] [Indexed: 12/27/2022] Open
Abstract
The human ubiquitin ligase HUWE1 has key roles in tumorigenesis, yet it is unkown how its activity is regulated. We present the crystal structure of a C-terminal part of HUWE1, including the catalytic domain, and reveal an asymmetric auto-inhibited dimer. We show that HUWE1 dimerizes in solution and self-associates in cells, and that both occurs through the crystallographic dimer interface. We demonstrate that HUWE1 is inhibited in cells and that it can be activated by disruption of the dimer interface. We identify a conserved segment in HUWE1 that counteracts dimer formation by associating with the dimerization region intramolecularly. Our studies reveal, intriguingly, that the tumor suppressor p14ARF binds to this segment and may thus shift the conformational equilibrium of HUWE1 toward the inactive state. We propose a model, in which the activity of HUWE1 underlies conformational control in response to physiological cues-a mechanism that may be exploited for cancer therapy.
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Affiliation(s)
- Bodo Sander
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Wenshan Xu
- Comprehensive Cancer Center Mainfranken, Würzburg, Germany
- Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
| | - Martin Eilers
- Comprehensive Cancer Center Mainfranken, Würzburg, Germany
- Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Nikita Popov
- Comprehensive Cancer Center Mainfranken, Würzburg, Germany
- Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
| | - Sonja Lorenz
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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22
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Integrating computational methods and experimental data for understanding the recognition mechanism and binding affinity of protein-protein complexes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 128:33-38. [PMID: 28069340 DOI: 10.1016/j.pbiomolbio.2017.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 01/04/2017] [Accepted: 01/05/2017] [Indexed: 01/09/2023]
Abstract
Protein-protein interactions perform several functions inside the cell. Understanding the recognition mechanism and binding affinity of protein-protein complexes is a challenging problem in experimental and computational biology. In this review, we focus on two aspects (i) understanding the recognition mechanism and (ii) predicting the binding affinity. The first part deals with computational techniques for identifying the binding site residues and the contribution of important interactions for understanding the recognition mechanism of protein-protein complexes in comparison with experimental observations. The second part is devoted to the methods developed for discriminating high and low affinity complexes, and predicting the binding affinity of protein-protein complexes using three-dimensional structural information and just from the amino acid sequence. The overall view enhances our understanding of the integration of experimental data and computational methods, recognition mechanism of protein-protein complexes and the binding affinity.
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23
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Krist DT, Park S, Boneh GH, Rice SE, Statsyuk AV. UbFluor: A Mechanism-Based Probe for HECT E3 Ligases. Chem Sci 2016; 7:5587-5595. [PMID: 27482366 PMCID: PMC4965700 DOI: 10.1039/c6sc01167e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Homologous to E6AP Carboxyl Terminus E3 ubiquitin ligases (HECT, ~28 known) are genetically implicated in cancer, neurological, hypertensive, and autoimmune disorders, and are potential drug targets to treat these diseases. The major bottleneck in the field of HECT E3s is a lack of simple assays to quantify the enzymatic activity of these enzymes in the presence of small molecules. Typical assays require E1, E2, HECT E3, ubiquitin (Ub), ATP and additional reagents to detect the resulting free poly-ubiquitin chains. To address this need, we developed UbFluor, a fluorescent thioester conjugate between the C-terminus of Ub and fluorescein-thiol (Fluor-SH). UbFluor is a mechanism-based probe that undergoes a direct transthiolation reaction with the catalytic cysteine of the model HECT E3 ligase Rsp5, producing the catalytically active Rsp5~Ub (~ indicates thioester) accompanied by release of Fluor-SH. The kinetics of this two-component reaction can be easily monitored with real-time fluorescence polarization (FP) assays. Importantly, UbFluor eliminates the need to use SDS-PAGE, ATP, E1, E2 enzymes, and extra poly-ubiquitin chain detection reagents. Although the developed system lacks ATP, E1 and E2 enzymes, we show that UbFluor can recapitulate the native ubiquitination reaction by detecting and quantifying defects in transthiolation and isopeptide ligation of Rsp5 HECT E3 alanine mutants. Based on our findings, we show that UbFluor can be utilized to conduct high-throughput screens (HTS) of small molecules against HECT ligases.
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Affiliation(s)
- David T Krist
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Northwestern University, Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208
| | - Sungjin Park
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Northwestern University, Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208; Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois, 60611, USA
| | - Galyah H Boneh
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Northwestern University, Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208
| | - Sarah E Rice
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois, 60611, USA
| | - Alexander V Statsyuk
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Northwestern University, Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208
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24
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LaSalle JM, Reiter LT, Chamberlain SJ. Epigenetic regulation of UBE3A and roles in human neurodevelopmental disorders. Epigenomics 2015; 7:1213-28. [PMID: 26585570 DOI: 10.2217/epi.15.70] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The E3 ubiquitin ligase UBE3A, also known as E6-AP, has a multitude of ascribed functions and targets relevant to human health and disease. Epigenetic regulation of the UBE3A gene by parentally imprinted noncoding transcription within human chromosome 15q11.2-q13.3 is responsible for the maternal-specific effects of 15q11.2-q13.3 deletion or duplication disorders. Here, we review the evidence for diverse and emerging roles for UBE3A in the proteasome, synapse and nucleus in regulating protein stability and transcription as well as the current mechanistic understanding of UBE3A imprinting in neurons. Angelman and Dup15q syndromes as well as experimental models of these neurodevelopmental disorders are highlighted as improving understanding of UBE3A and its complex regulation for improving therapeutic strategies.
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Affiliation(s)
- Janine M LaSalle
- Medical Microbiology & Immunology, Genome Center & MIND Institute, University of California, Davis, CA 95616, USA
| | - Lawrence T Reiter
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN 38163, USA.,Department of Neurology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Stormy J Chamberlain
- Department of Genetics & Developmental Biology & Stem Cell Institute, University of Connecticut, Farmington, CT 06030, USA
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25
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Krist DT, Statsyuk AV. Catalytically Important Residues of E6AP Ubiquitin Ligase Identified Using Acid-Cleavable Photo-Cross-Linkers. Biochemistry 2015; 54:4411-4. [PMID: 26161728 DOI: 10.1021/acs.biochem.5b00625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inactivation of the E6AP E3 ubiquitin ligase (UBE3A gene) causes Angelman syndrome, while aberrant degradation of p53 by E6AP is implicated in cervical cancers. Herein, we describe the development of photo-cross-linkers to discover catalytic residues of E6AP. Using these cross-linkers, we identified covalent modifications of the E6AP catalytic cysteine and two lysines: Lys(847) and Lys(799). Lys(847) is required for the formation of Lys(48)-linked polyubiquitin chains, while the K799A E6AP mutant was more active at producing Lys(48)-linked polyubiquitin chains. Thus, opposing roles of Lys(799) and Lys(847) pave the path forward to pharmacological inhibitors or activators of E6AP for therapeutic purposes.
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Affiliation(s)
- David T Krist
- Chemistry of Life Processes Institute, Department of Chemistry, Northwestern University, Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Alexander V Statsyuk
- Chemistry of Life Processes Institute, Department of Chemistry, Northwestern University, Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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26
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Stanley M, Han C, Knebel A, Murphy P, Shpiro N, Virdee S. Orthogonal thiol functionalization at a single atomic center for profiling transthiolation activity of E1 activating enzymes. ACS Chem Biol 2015; 10:1542-54. [PMID: 25845023 DOI: 10.1021/acschembio.5b00118] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Transthiolation is a fundamental biological reaction and is utilized by many enzymes involved in the conjugation of ubiquitin and ubiquitin-like proteins. However, tools that enable selective profiling of this activity are lacking. Transthiolation requires cysteine-cysteine juxtaposition; therefore a method that enables irreversible "stapling" of proximal thiols would facilitate the development of novel probes that could be used to profile this activity. Herein, we characterize biocompatible chemistry that enables sequential functionalization of cysteines within proteins at a single atomic center. We use our method to develop a new class of activity-based probe that profiles transthiolation activity of human E1 activating enzymes. We demonstrate use in vitro and in situ and compatibility with competitive activity-based protein profiling. We also use the probe to gain insight into the determinants of transthiolation between E2 and a RING-in-between-RING (RBR) E3 ligase. Furthermore, we anticipate that this method of thiol functionalization will have broad utility by enabling simple redox-stable cross-linking of proximal cysteines in general.
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Affiliation(s)
- Mathew Stanley
- MRC Protein
Phosphorylation
and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1
5EH, United Kingdom
| | - Cong Han
- MRC Protein
Phosphorylation
and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1
5EH, United Kingdom
| | - Axel Knebel
- MRC Protein
Phosphorylation
and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1
5EH, United Kingdom
| | - Paul Murphy
- MRC Protein
Phosphorylation
and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1
5EH, United Kingdom
| | - Natalia Shpiro
- MRC Protein
Phosphorylation
and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1
5EH, United Kingdom
| | - Satpal Virdee
- MRC Protein
Phosphorylation
and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1
5EH, United Kingdom
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27
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Abstract
The human genome encodes several hundred E3 ubiquitin ligases containing RING domains, and around 28 containing HECT domains. These enzymes catalyze the transfer of ubiquitin from E2 enzyme thioesters to a huge range of substrates and play crucial roles in many cellular functions. This makes them attractive potential therapeutic targets. However, they have proven difficult to inhibit: very few good inhibitors exist for RING domain ligases, and none have been described for HECT ligases. Here we show that bicyclic peptides isolated by phage display [Heinis C, Rutherford T, Freund S, Winter G (2009) Nat Chem Biol. 5(7):502-507] can target the E2 binding sites on the HECT domains of Smurf2, Nedd4, Mule/Huwe1, and WWP1, and thus act as specific inhibitors of these enzymes in vitro. By screening for displacement of one of these peptides from Smurf2, we were able to identify a small molecule, heclin (HECT ligase inhibitor), which inhibits several HECT ligases in tissue culture cells. In vitro, heclin does not block E2 binding but causes a conformational change that results in oxidation of the active site Cys. This demonstrates that HECT domains are potentially druggable and provides molecules that may be of experimental use. Heclin kills HEK293 cells growing in culture, consistent with an essential role for HECT ligase activity in mammalian cells.
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28
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Orthogonal ubiquitin transfer through engineered E1-E2 cascades for protein ubiquitination. ACTA ACUST UNITED AC 2013; 19:1265-77. [PMID: 23102221 DOI: 10.1016/j.chembiol.2012.07.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 07/26/2012] [Accepted: 07/31/2012] [Indexed: 11/20/2022]
Abstract
Protein modification by ubiquitin (UB) controls diverse cellular processes. UB is conjugated to cellular proteins by sequential transfer through an E1-E2-E3 enzymatic cascade. The cross-activities of 2 E1s, 50 E2s and thousands of E3s encoded by the human genome make it difficult to identify the substrate proteins of a specific E3 enzyme in the cell. One way to solve this problem is to engineer an orthogonal UB transfer (OUT) cascade in which the engineered UB (xUB) is relayed by engineered E1, E2 and E3 enzymes (xE1, xE2, xE3) to modify the substrate proteins of a specific E3. Here, we use phage display and mutagenesis to construct xUB-xE1 and xE1-xE2 pairs that are orthogonal to the native E1 and E2 enzymes. Our work on engineering the UB transfer cascades will enable us to use OUT to map the signal transduction networks mediated by protein ubiquitination.
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29
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Ronchi VP, Klein JM, Haas AL. E6AP/UBE3A ubiquitin ligase harbors two E2~ubiquitin binding sites. J Biol Chem 2013; 288:10349-60. [PMID: 23439649 DOI: 10.1074/jbc.m113.458059] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
By exploiting (125)I-polyubiquitin chain formation as a functional readout of enzyme activity, we have quantitatively examined the mechanism of human E6AP/UBE3A for the first time. Initial rate studies identify UbcH7 as the cognate E2 carrier protein for E6AP, although related Ubc5 isoforms and the ISG15-specific UbcH8 paralog also support E6AP with reduced efficacy due to impaired binding and catalytic competence. Initial rates of polyubiquitin chain formation displayed hyperbolic kinetics with respect to UbcH7 concentration (K(m) = 57.6 ± 5.7 nM and kcat = 0.032 ± 0.001 s(-1)) and substrate inhibition above 2 μM. Competitive inhibition by an isosteric UbcH7C86S-ubiquitin oxyester substrate analog (K(i) = 64 ± 18 nM) demonstrates that Km reflects intrinsic substrate affinity. In contrast, noncompetitive inhibition by a UbcH7C86A product analog (K(i) = 7 ± 0.7 μM) and substrate inhibition at high concentrations require two functionally distinct E2∼ubiquitin substrate binding sites. The kinetics of polyubiquitin chain formation reflect binding at a cryptic Site 1 not previously recognized that catalyzes E6AP∼ubiquitin thioester formation. Subsequent binding of E2∼ubiquitin at the canonical Site 2 present in the extant crystal structure is responsible for polyubiquitin chain elongation. Other rate studies show that the conserved -4 Phe(849) residue is required for polyubiquitin chain formation rather than target protein conjugation as originally suggested. The present studies unambiguously preclude earlier models for the mechanism of Hect domain-catalyzed conjugation through the canonical binding site suggested by the crystal structure and define a novel two-step mechanism for formation of the polyubiquitin degradation signal.
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Affiliation(s)
- Virginia P Ronchi
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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30
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Aguado-Llera D, Doménech R, Marenchino M, Vidal M, Neira JL. Non-canonical residues of the marginally stable monomeric ubiquitin conjugase from goldfish are involved in binding to the C terminus of Ring 1B. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1824:991-1001. [PMID: 22609416 DOI: 10.1016/j.bbapap.2012.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 05/04/2012] [Accepted: 05/09/2012] [Indexed: 06/01/2023]
Abstract
E2 ubiquitin conjugases are ~20kDa enzymes involved in ubiquitination processes in eukaryotes. The E2s are responsible for the transference of ubiquitin (Ub) to E3 enzymes, which finally transfer Ub to diverse target proteins, labelling them for degradation, localization and regulation. Although their functions are relatively well-characterized, their conformational stabilities are poorly known. In this work, we have used, as a model for our biophysical and binding studies, the E2-C from Carassius auratus (goldfish), a homologue of the human ubiquitin conjugase UbcH10. E2-C(ca) was a monomeric protein with an elongated shape; moreover, the protein was only marginally stable within a narrow pH range (from 6.0 to 8.0). We also explored the binding of E2-C(ca) towards non-canonical E3 ligases. Binding of E2-C(ca) to the C terminus of murine Ring 1B (C-Ring1B), which does not contain the RING finger of the whole Ring1B, occurred with an affinity of ~400nM, as shown by fluorescence and ITC. Furthermore, binding of E2-C(ca) to C-Ring1B did not occur at its canonical E2-loops, since residues M43 and F53, far away from those loops, were involved in binding. Thus, the C-Ring1B-interacting region of E2-C(ca) comprises the first β-strand and nearby residues.
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Affiliation(s)
- David Aguado-Llera
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Alicante, Spain
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31
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Yamagishi Y, Shoji I, Miyagawa S, Kawakami T, Katoh T, Goto Y, Suga H. Natural product-like macrocyclic N-methyl-peptide inhibitors against a ubiquitin ligase uncovered from a ribosome-expressed de novo library. ACTA ACUST UNITED AC 2012; 18:1562-70. [PMID: 22195558 DOI: 10.1016/j.chembiol.2011.09.013] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 09/20/2011] [Accepted: 09/20/2011] [Indexed: 10/14/2022]
Abstract
Naturally occurring peptides often possess macrocyclic and N-methylated backbone. These features grant them structural rigidity, high affinity to targets, proteolytic resistance, and occasionally membrane permeability. Because such peptides are produced by either nonribosomal peptide synthetases or enzymatic posttranslational modifications, it is yet a formidable challenge in degenerating sequence or length and preparing libraries for screening bioactive molecules. Here, we report a new means of synthesizing a de novo library of "natural product-like" macrocyclic N-methyl-peptides using translation machinery under the reprogrammed genetic code, which is coupled with an in vitro display technique, referred to as RaPID (random nonstandard peptides integrated discovery) system. This system allows for rapid selection of strong binders against an arbitrarily chosen therapeutic target. Here, we have demonstrated the selection of anti-E6AP macrocyclic N-methyl-peptides, one of which strongly inhibits polyubiqutination of proteins such as p53.
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Affiliation(s)
- Yusuke Yamagishi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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32
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Sheng Y, Hong JH, Doherty R, Srikumar T, Shloush J, Avvakumov GV, Walker JR, Xue S, Neculai D, Wan JW, Kim SK, Arrowsmith CH, Raught B, Dhe-Paganon S. A human ubiquitin conjugating enzyme (E2)-HECT E3 ligase structure-function screen. Mol Cell Proteomics 2012; 11:329-41. [PMID: 22496338 DOI: 10.1074/mcp.o111.013706] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Here we describe a systematic structure-function analysis of the human ubiquitin (Ub) E2 conjugating proteins, consisting of the determination of 15 new high-resolution three-dimensional structures of E2 catalytic domains, and autoubiquitylation assays for 26 Ub-loading E2s screened against a panel of nine different HECT (homologous to E6-AP carboxyl terminus) E3 ligase domains. Integration of our structural and biochemical data revealed several E2 surface properties associated with Ub chain building activity; (1) net positive or neutral E2 charge, (2) an "acidic trough" located near the catalytic Cys, surrounded by an extensive basic region, and (3) similarity to the previously described HECT binding signature in UBE2L3 (UbcH7). Mass spectrometry was used to characterize the autoubiquitylation products of a number of functional E2-HECT pairs, and demonstrated that HECT domains from different subfamilies catalyze the formation of very different types of Ub chains, largely independent of the E2 in the reaction. Our data set represents the first comprehensive analysis of E2-HECT E3 interactions, and thus provides a framework for better understanding the molecular mechanisms of ubiquitylation.
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Affiliation(s)
- Yi Sheng
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
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33
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Stoffregen M, Schwer M, Renschler F, Wiesner S. Methionine Scanning as an NMR Tool for Detecting and Analyzing Biomolecular Interaction Surfaces. Structure 2012; 20:573-81. [DOI: 10.1016/j.str.2012.02.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 01/27/2012] [Accepted: 02/03/2012] [Indexed: 11/25/2022]
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34
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Kar G, Keskin O, Nussinov R, Gursoy A. Human proteome-scale structural modeling of E2-E3 interactions exploiting interface motifs. J Proteome Res 2012; 11:1196-207. [PMID: 22149024 PMCID: PMC3285560 DOI: 10.1021/pr2009143] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ubiquitination is crucial for many cellular processes such as protein degradation, DNA repair, transcription regulation, and cell signaling. Ubiquitin attachment takes place via a sequential enzymatic cascade involving ubiquitin activation (by E1 enzymes), ubiquitin conjugation (by E2 enzymes), and ubiquitin substrate tagging (by E3 enzymes). E3 ligases mediate ubiquitin transfer from E2s to substrates and as such confer substrate specificity. Although E3s can interact and function with numerous E2s, it is still unclear how they choose which E2 to use. Identifying all E2 partners of an E3 is essential for inferring the principles guiding E2 selection by an E3. Here we model the interactions of E3 and E2 proteins in a large, proteome-scale strategy based on interface structural motifs, which allows elucidation of (1) which E3s interact with which E2s in the human ubiquitination pathway and (2) how they interact with each other. Interface analysis of E2-E3 complexes reveals that loop L1 of E2s is critical for binding; the residue in the sixth position in loop L1 is widely utilized as an interface hot spot and appears indispensible for E2 interactions. Other loop L1 residues also confer specificity on the E2-E3 interactions: HECT E3s are in contact with the residue in the second position in loop L1 of E2s, but this is not the case for the RING finger type E3s. Our modeled E2-E3 complexes illuminate how slight sequence variations in E2 residues may contribute to specificity in E3 binding. These findings may be important for discovering drug candidates targeting E3s, which have been implicated in many diseases.
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Affiliation(s)
- Gozde Kar
- Center for Computational Biology and Bioinformatics and College of Engineering, Koc University, Rumelifeneri Yolu, 34450 Sariyer Istanbul, Turkey
| | - Ozlem Keskin
- Center for Computational Biology and Bioinformatics and College of Engineering, Koc University, Rumelifeneri Yolu, 34450 Sariyer Istanbul, Turkey
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology Program, NCI-Frederick, Frederick, MD 21702
- Sackler Inst. Of Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Attila Gursoy
- Center for Computational Biology and Bioinformatics and College of Engineering, Koc University, Rumelifeneri Yolu, 34450 Sariyer Istanbul, Turkey
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35
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Chen R, Chen W, Yang S, Wu D, Wang Y, Tian Y, Shi Y. Rigorous assessment and integration of the sequence and structure based features to predict hot spots. BMC Bioinformatics 2011; 12:311. [PMID: 21798070 PMCID: PMC3176265 DOI: 10.1186/1471-2105-12-311] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 07/29/2011] [Indexed: 12/02/2022] Open
Abstract
Background Systematic mutagenesis studies have shown that only a few interface residues termed hot spots contribute significantly to the binding free energy of protein-protein interactions. Therefore, hot spots prediction becomes increasingly important for well understanding the essence of proteins interactions and helping narrow down the search space for drug design. Currently many computational methods have been developed by proposing different features. However comparative assessment of these features and furthermore effective and accurate methods are still in pressing need. Results In this study, we first comprehensively collect the features to discriminate hot spots and non-hot spots and analyze their distributions. We find that hot spots have lower relASA and larger relative change in ASA, suggesting hot spots tend to be protected from bulk solvent. In addition, hot spots have more contacts including hydrogen bonds, salt bridges, and atomic contacts, which favor complexes formation. Interestingly, we find that conservation score and sequence entropy are not significantly different between hot spots and non-hot spots in Ab+ dataset (all complexes). While in Ab- dataset (antigen-antibody complexes are excluded), there are significant differences in two features between hot pots and non-hot spots. Secondly, we explore the predictive ability for each feature and the combinations of features by support vector machines (SVMs). The results indicate that sequence-based feature outperforms other combinations of features with reasonable accuracy, with a precision of 0.69, a recall of 0.68, an F1 score of 0.68, and an AUC of 0.68 on independent test set. Compared with other machine learning methods and two energy-based approaches, our approach achieves the best performance. Moreover, we demonstrate the applicability of our method to predict hot spots of two protein complexes. Conclusion Experimental results show that support vector machine classifiers are quite effective in predicting hot spots based on sequence features. Hot spots cannot be fully predicted through simple analysis based on physicochemical characteristics, but there is reason to believe that integration of features and machine learning methods can remarkably improve the predictive performance for hot spots.
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Affiliation(s)
- Ruoying Chen
- 1College of Life Sciences, Graduate University of Chinese Academy ofSciences, Beijing 100049, China
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36
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Abstract
Ubiquitination is a post-translational modification pathway involved in myriad cellular regulation and disease pathways. The Ub (ubiquitin) transfer cascade requires three enzyme activities: a Ub-activating (E1) enzyme, a Ub-conjugating (E2) enzyme, and a Ub ligase (E3). Because the E2 is responsible both for E3 selection and substrate modification, E2s function at the heart of the Ub transfer pathway and are responsible for much of the diversity of Ub cellular signalling. There are currently over 90 three-dimensional structures for E2s, both alone and in complex with protein binding partners, providing a wealth of information regarding how E2s are recognized by a wide variety of proteins. In the present review, we describe the prototypical E2-E3 interface and discuss limitations of current methods to identify cognate E2-E3 partners. We present non-canonical E2-protein interactions and highlight the economy of E2s in their ability to facilitate many protein-protein interactions at nearly every surface on their relatively small and compact catalytic domain. Lastly, we compare the structures of conjugated E2~Ub species, their unique protein interactions and the mechanistic insights provided by species that are poised to transfer Ub.
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37
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Lin DYW, Diao J, Zhou D, Chen J. Biochemical and structural studies of a HECT-like ubiquitin ligase from Escherichia coli O157:H7. J Biol Chem 2011; 286:441-9. [PMID: 20980253 PMCID: PMC3013003 DOI: 10.1074/jbc.m110.167643] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 09/28/2010] [Indexed: 11/21/2022] Open
Abstract
Many microbial pathogens deliver effector proteins via the type III secretion system into infected host cells. Elucidating the function of these effectors is essential for our understanding of pathogenesis. Here, we describe biochemical and structural characterization of an effector protein (NleL) from Escherichia coli O157:H7, a widespread pathogen causing severe foodborne diseases. We show that NleL functionally and structurally mimics eukaryotic HECT E3 ligases and catalyzes formation of unanchored polyubiquitin chains using Lys(6) and Lys(48) linkage. The catalytic cysteine residue forms a thioester intermediate with ubiquitin. The structure of NleL contains two domains, a β-helix domain formed by pentapeptide repeats and a bilobed catalytic domain reminiscent of the N- and C-lobe architecture of HECT E3s. Six structures of NleL observed in two crystal forms revealed a large range of different positions of the C-lobe relative to the N-lobe, indicating that the helix linking the two lobes is extremely flexible. Comparing the structure of NleL with that of the Salmonella homolog SopA showed that the orientation of the C-lobes differ by as much as 108°, suggesting that large movements of the C-lobe may be required to facilitate the transfer of ubiquitin from E2 to the substrate. These results provide critical knowledge toward understanding the molecular mechanism by which pathogens utilize the host ubiquitination system during infection.
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Affiliation(s)
| | - Jianbo Diao
- the Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Daoguo Zhou
- From the Department of Biological Sciences, Purdue University and
| | - Jue Chen
- From the Department of Biological Sciences, Purdue University and
- Howard Hughes Medical Institute, West Lafayette, Indiana 47907 and
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38
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Prediction of protein interaction hot spots using rough set-based multiple criteria linear programming. J Theor Biol 2010; 269:174-80. [PMID: 21035465 DOI: 10.1016/j.jtbi.2010.10.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/01/2010] [Accepted: 10/16/2010] [Indexed: 11/21/2022]
Abstract
Protein-protein interactions are fundamentally important in many biological processes and it is in pressing need to understand the principles of protein-protein interactions. Mutagenesis studies have found that only a small fraction of surface residues, known as hot spots, are responsible for the physical binding in protein complexes. However, revealing hot spots by mutagenesis experiments are usually time consuming and expensive. In order to complement the experimental efforts, we propose a new computational approach in this paper to predict hot spots. Our method, Rough Set-based Multiple Criteria Linear Programming (RS-MCLP), integrates rough sets theory and multiple criteria linear programming to choose dominant features and computationally predict hot spots. Our approach is benchmarked by a dataset of 904 alanine-mutated residues and the results show that our RS-MCLP method performs better than other methods, e.g., MCLP, Decision Tree, Bayes Net, and the existing HotSprint database. In addition, we reveal several biological insights based on our analysis. We find that four features (the change of accessible surface area, percentage of the change of accessible surface area, size of a residue, and atomic contacts) are critical in predicting hot spots. Furthermore, we find that three residues (Tyr, Trp, and Phe) are abundant in hot spots through analyzing the distribution of amino acids.
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39
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Gromiha MM, Yokota K, Fukui K. Energy based approach for understanding the recognition mechanism in protein-protein complexes. MOLECULAR BIOSYSTEMS 2010; 5:1779-86. [PMID: 19593470 DOI: 10.1039/b904161n] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Protein-protein interactions play an essential role in the regulation of various cellular processes. Understanding the recognition mechanism of protein-protein complexes is a challenging task in molecular and computational biology. In this work, we have developed an energy based approach for identifying the binding sites and important residues for binding in protein-protein complexes. The new approach is different from the traditional distance based contacts in which the repulsive interactions are treated as binding sites as well as the contacts within a specific cutoff have been treated in the same way. We found that the residues and residue-pairs with charged and aromatic side chains are important for binding. These residues influence to form cation-, electrostatic and aromatic interactions. Our observation has been verified with the experimental binding specificity of protein-protein complexes and found good agreement with experiments. Based on these results we have proposed a novel mechanism for the recognition of protein-protein complexes: the charged and aromatic residues in receptor and ligand initiate recognition by making suitable interactions between them; the neighboring hydrophobic residues assist the stability of complex along with other hydrogen bonding partners by the polar residues. Further, the propensity of residues in the binding sites of receptors and ligands, atomic contributions and the influence on secondary structure will be discussed.
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Affiliation(s)
- M Michael Gromiha
- Computational Biology Research Center, National Institute of Advanced Industrial Science and Technology, 2-42 Aomi, Koto-ku, Tokyo 135-0064, Japan.
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40
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Kamadurai HB, Souphron J, Scott DC, Duda DM, Miller DJ, Stringer D, Piper RC, Schulman BA. Insights into ubiquitin transfer cascades from a structure of a UbcH5B approximately ubiquitin-HECT(NEDD4L) complex. Mol Cell 2010; 36:1095-102. [PMID: 20064473 DOI: 10.1016/j.molcel.2009.11.010] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 09/01/2009] [Accepted: 09/23/2009] [Indexed: 01/25/2023]
Abstract
In E1-E2-E3 ubiquitin (Ub) conjugation cascades, the E2 first forms a transient E2 approximately Ub covalent complex and then interacts with an E3 for Ub transfer. For cascades involving E3s in the HECT class, Ub is transferred from an associated E2 to the acceptor cysteine in the HECT domain C lobe. To gain insights into this process, we determined the crystal structure of a complex between the HECT domain of NEDD4L and the E2 UbcH5B bearing a covalently linked Ub at its active site (UbcH5B approximately Ub). Noncovalent interactions between UbcH5B and the HECT N lobe and between Ub and the HECT domain C lobe lead to an overall compact structure, with the Ub C terminus sandwiched between UbcH5B and HECT domain active sites. The structure suggests a model for E2-to-HECT Ub transfer, in which interactions between a donor Ub and an acceptor domain constrain upstream and downstream enzymes for conjugation.
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Affiliation(s)
- Hari B Kamadurai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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41
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Purbeck C, Eletr ZM, Kuhlman B. Kinetics of the Transfer of Ubiquitin from UbcH7 to E6AP. Biochemistry 2010; 49:1361-3. [DOI: 10.1021/bi9014693] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carrie Purbeck
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Ziad M. Eletr
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Brian Kuhlman
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
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42
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David Y, Ziv T, Admon A, Navon A. The E2 ubiquitin-conjugating enzymes direct polyubiquitination to preferred lysines. J Biol Chem 2010; 285:8595-604. [PMID: 20061386 DOI: 10.1074/jbc.m109.089003] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The ubiquitin-proteasome pathway plays a crucial role in many cellular processes by degrading substrates tagged by polyubiquitin chains, linked mostly through lysine 48 of ubiquitin. Although polymerization of ubiquitin via its six other lysine residues exists in vivo as part of various physiological pathways, the molecular mechanisms that determine the type of polyubiquitin chains remained largely unknown. We undertook a systematic, in vitro, approach to evaluate the role of E2 enzymes in determining the topology of polyubiquitin. Because this study was performed in the absence of an E3 enzyme, our data indicate that the E2 enzymes are capable of directing the ubiquitination process to distinct subsets of ubiquitin lysines, depending on the specific E2 utilized. Moreover, our findings are in complete agreement with prior analyses of lysine preference assigned to certain E2s in the context of E3 (in vitro and in vivo). Finally, our findings support the rising notion that the functional unit of E2 is a dimer. To our knowledge, this is the first systematic indication for the involvement of E2 enzymes in specifying polyubiquitin chain assembly.
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Affiliation(s)
- Yael David
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel
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43
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Lee W, Zhang Y, Mukhyala K, Lazarus RA, Zhang Z. Bi-directional SIFT predicts a subset of activating mutations. PLoS One 2009; 4:e8311. [PMID: 20011534 PMCID: PMC2788704 DOI: 10.1371/journal.pone.0008311] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Accepted: 11/18/2009] [Indexed: 11/19/2022] Open
Abstract
Advancements in sequencing technologies have empowered recent efforts to identify polymorphisms and mutations on a global scale. The large number of variations and mutations found in these projects requires high-throughput tools to identify those that are most likely to have an impact on function. Numerous computational tools exist for predicting which mutations are likely to be functional, but none that specifically attempt to identify mutations that result in hyperactivation or gain-of-function. Here we present a modified version of the SIFT (Sorting Intolerant from Tolerant) algorithm that utilizes protein sequence alignments with homologous sequences to identify functional mutations based on evolutionary fitness. We show that this bi-directional SIFT (B-SIFT) is capable of identifying experimentally verified activating mutants from multiple datasets. B-SIFT analysis of large-scale cancer genotyping data identified potential activating mutations, some of which we have provided detailed structural evidence to support. B-SIFT could prove to be a valuable tool for efforts in protein engineering as well as in identification of functional mutations in cancer.
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Affiliation(s)
- William Lee
- Department of Bioinformatics, Genentech, Inc., South San Francisco, California, United States of America
| | - Yan Zhang
- Department of Bioinformatics, Genentech, Inc., South San Francisco, California, United States of America
| | - Kiran Mukhyala
- Department of Bioinformatics, Genentech, Inc., South San Francisco, California, United States of America
| | - Robert A. Lazarus
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California, United States of America
| | - Zemin Zhang
- Department of Bioinformatics, Genentech, Inc., South San Francisco, California, United States of America
- * E-mail:
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44
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van Wijk SJL, Timmers HTM. The family of ubiquitin-conjugating enzymes (E2s): deciding between life and death of proteins. FASEB J 2009; 24:981-93. [PMID: 19940261 DOI: 10.1096/fj.09-136259] [Citation(s) in RCA: 283] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The family of ubiquitin-conjugating (E2) enzymes is characterized by the presence of a highly conserved ubiquitin-conjugating (UBC) domain. These domains accommodate the ATP-activated ubiquitin (Ub) or ubiquitin-like (UBL) protein via a covalently linked thioester onto its active-site residue. E2 enzymes act via selective protein-protein interactions with the E1 and E3 enzymes and connect activation to covalent modification. By doing so, E2s differentiate effects on downstream substrates, either with a single Ub/UBL molecule or as a chain. While E3s are involved in substrate selection, E2s are the main determinants for selection of the lysine to construct ubiquitin chains, which thereby directly control the cellular fate of the substrate. In humans, 35 active E2 enzymes have been identified so far, while other eukaryotic genomes harbor 16 to 35 E2 family members. Some E2s possess N- and/or C-terminal extensions that mediate E2-specific processes. During the past two decades, strong support has led to the control of E2 enzymes in decisions concerning the life or death of a protein. Here, we summarize current knowledge and recent developments on E2 enzymes with respect to structural characteristics and functions. From this we propose a shell-like model to rationalize the selectivity of these key enzymes in directing Ub/UBL-conjugation pathways.-Van Wijk, S. J. L., Timmers, H. T. M. The family of ubiquitin-conjugating enzymes (E2s): deciding between life and death of proteins.
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Affiliation(s)
- Sjoerd J L van Wijk
- Department of Physiological Chemistry, Division of Biomedical Genetics, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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45
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Christensen DE, Klevit RE. Dynamic interactions of proteins in complex networks: identifying the complete set of interacting E2s for functional investigation of E3-dependent protein ubiquitination. FEBS J 2009; 276:5381-9. [PMID: 19712108 DOI: 10.1111/j.1742-4658.2009.07249.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A ubiquitin ligase (E3) functions at the crossroad between ubiquitin activation and the attachment of ubiquitin to protein substrates. During this process, the E3 interacts with both a substrate and a ubiquitin-conjugating enzyme (E2). Although a major goal when investigating an E3 is to identify its substrates, recent evidence indicates that the E2 dictates the type of ubiquitin modification that will occur on the substrate. There are approximately 30 E2s identified in the human genome, many of which remain to be characterized. We found that the RING E3 BRCA1/BARD1 can interact with 10 different E2s. The ability of BRCA1 to interact with multiple E2s is likely to be a common feature among other RING and U-box E3s. We and others have also found that certain E2s show a preference for attaching either the first ubiquitin to a substrate lysine or ubiquitin to itself (chain building), suggesting that E2s may play a role in dictating product formation. Therefore, when investigating the functions of an E3 it is advisable to identify all E2s that interact with the E3 so that these can be used in E3-dependent substrate-ubiquitination assays. We describe a method used to identify all the E2s that interact with BRCA1. Defining the set of E2s that interact with other RING and U-box E3s will open the door for predictive models and lead to a better understand of substrate ubiquitination.
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Affiliation(s)
- Devin E Christensen
- Department of Biochemistry, University of Utah, Salt Lake City, UT 98195, USA
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46
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Polyubiquitination by HECT E3s and the determinants of chain type specificity. Mol Cell Biol 2009; 29:3307-18. [PMID: 19364824 DOI: 10.1128/mcb.00240-09] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polyubiquitination can mediate several different biochemical functions, determined in part by which lysine of ubiquitin is used to link the polyubiquitin chain. Among the HECT domain ubiquitin ligases, some, such as human E6AP, preferentially catalyze the formation of K48-linked polyubiquitin chains, while others, including Saccharomyces cerevisiae Rsp5 and human Itch, preferentially catalyze the formation of K63-linked chains. The features of HECT E3s that determine their chain type specificities have not been identified. We show here that chain type specificity is a function solely of the Rsp5 HECT domain, that the identity of the cooperating E2 protein does not influence the chain type specificity, that single chains produced by Rsp5 contain between 12 and 30 ubiquitin moieties, and that the determinants of chain type specificity are located within the last 60 amino acids of the C lobe of the HECT domain. Our results are also consistent with a simple sequential-addition mechanism for polyubiquitination by Rsp5, rather than a mechanism involving the formation of either E2- or E3-linked polyubiquitin chain transfers.
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47
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Park HJ, Zheng H, Kulkarni D, Kerrigan J, Pungaliya P, Saleem A, Rubin EH. Identification of phosphorylation sites of TOPORS and a role for serine 98 in the regulation of ubiquitin but not SUMO E3 ligase activity. Biochemistry 2009; 47:13887-96. [PMID: 19053840 DOI: 10.1021/bi801904q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
TOPORS is the first example of a protein that possesses both ubiquitin and SUMO E3 ligase activity. The ubiquitination activity maps to a conserved RING domain in the N-terminal region of the protein, which is not required for sumoylation activity. Similar to other E3 ligases, it is likely that the ubiquitin and sumoylation activities of TOPORS are regulated by post-translational modifications. Therefore, we employed mass spectrometry to identify post-translational modifications of TOPORS. Several putative phosphorylated regions were identified in conserved regions of the protein. We investigated the role of phosphorylation of serine 98, which is adjacent to the RING domain, in both cells and in vitro. Mutation of serine 98 to aspartic acid resulted in an increase in the ubiquitin ligase activity of TOPORS both in cells and in vitro. In addition, this mutation increased the binding of TOPORS to the E2 enzyme UbcH5a both in vitro and in cells. Conversely, a phospho-deficient mutant (S98A) exhibited little change in ubiquitin ligase activity compared to wild-type TOPORS, both in cells and in vitro. Neither of the mutants affected the localization of TOPORS to punctate nuclear regions. In addition, neither mutant affected the SUMO ligase activity of TOPORS in cells or in vitro. Molecular modeling studies support a role for serine 98 in regulating TOPORS-E2 interactions. Our findings indicate that phosphorylation of serine 98 regulates the ubiquitin but not the SUMO ligase activity of TOPORS, consistent with a potential binary switch function for TOPORS in protein ubiquitination versus sumoylation.
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Affiliation(s)
- Hye-Jin Park
- Departments of Pharmacology and Medicine, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 195 Little Albany Street, New Brunswick, New Jersey 08901, USA
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48
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Sheng Y, Laister RC, Lemak A, Wu B, Tai E, Duan S, Lukin J, Sunnerhagen M, Srisailam S, Karra M, Benchimol S, Arrowsmith CH. Molecular basis of Pirh2-mediated p53 ubiquitylation. Nat Struct Mol Biol 2008. [PMID: 19043414 DOI: 10.1038/nsmb.1521.molecular] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Pirh2 (p53-induced RING-H2 domain protein; also known as Rchy1) is an E3 ubiquitin ligase involved in a negative-feedback loop with p53. Using NMR spectroscopy, we show that Pirh2 is a unique cysteine-rich protein comprising three modular domains. The protein binds nine zinc ions using a variety of zinc coordination schemes, including a RING domain and a left-handed beta-spiral in which three zinc ions align three consecutive small beta-sheets in an interleaved fashion. We show that Pirh2-p53 interaction is dependent on the C-terminal zinc binding module of Pirh2, which binds to the tetramerization domain of p53. As a result, Pirh2 preferentially ubiquitylates the tetrameric form of p53 in vitro and in vivo, suggesting that Pirh2 regulates protein turnover of the transcriptionally active form of p53.
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Affiliation(s)
- Yi Sheng
- Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Ontario M5G1L7, Canada
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49
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Molecular basis of Pirh2-mediated p53 ubiquitylation. Nat Struct Mol Biol 2008; 15:1334-42. [PMID: 19043414 DOI: 10.1038/nsmb.1521] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 10/30/2008] [Indexed: 11/08/2022]
Abstract
Pirh2 (p53-induced RING-H2 domain protein; also known as Rchy1) is an E3 ubiquitin ligase involved in a negative-feedback loop with p53. Using NMR spectroscopy, we show that Pirh2 is a unique cysteine-rich protein comprising three modular domains. The protein binds nine zinc ions using a variety of zinc coordination schemes, including a RING domain and a left-handed beta-spiral in which three zinc ions align three consecutive small beta-sheets in an interleaved fashion. We show that Pirh2-p53 interaction is dependent on the C-terminal zinc binding module of Pirh2, which binds to the tetramerization domain of p53. As a result, Pirh2 preferentially ubiquitylates the tetrameric form of p53 in vitro and in vivo, suggesting that Pirh2 regulates protein turnover of the transcriptionally active form of p53.
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50
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Bjelić S, Jelesarov I. A survey of the year 2007 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:289-312. [PMID: 18729242 DOI: 10.1002/jmr.909] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.
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Affiliation(s)
- Sasa Bjelić
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland
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