1
|
Chang YC, Oram MK, Bielinsky AK. SUMO-Targeted Ubiquitin Ligases and Their Functions in Maintaining Genome Stability. Int J Mol Sci 2021; 22:ijms22105391. [PMID: 34065507 PMCID: PMC8161396 DOI: 10.3390/ijms22105391] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 02/06/2023] Open
Abstract
Small ubiquitin-like modifier (SUMO)-targeted E3 ubiquitin ligases (STUbLs) are specialized enzymes that recognize SUMOylated proteins and attach ubiquitin to them. They therefore connect the cellular SUMOylation and ubiquitination circuits. STUbLs participate in diverse molecular processes that span cell cycle regulated events, including DNA repair, replication, mitosis, and transcription. They operate during unperturbed conditions and in response to challenges, such as genotoxic stress. These E3 ubiquitin ligases modify their target substrates by catalyzing ubiquitin chains that form different linkages, resulting in proteolytic or non-proteolytic outcomes. Often, STUbLs function in compartmentalized environments, such as the nuclear envelope or kinetochore, and actively aid in nuclear relocalization of damaged DNA and stalled replication forks to promote DNA repair or fork restart. Furthermore, STUbLs reside in the same vicinity as SUMO proteases and deubiquitinases (DUBs), providing spatiotemporal control of their targets. In this review, we focus on the molecular mechanisms by which STUbLs help to maintain genome stability across different species.
Collapse
|
2
|
Whalen JM, Freudenreich CH. Location, Location, Location: The Role of Nuclear Positioning in the Repair of Collapsed Forks and Protection of Genome Stability. Genes (Basel) 2020; 11:E635. [PMID: 32526925 PMCID: PMC7348918 DOI: 10.3390/genes11060635] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 05/29/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022] Open
Abstract
Components of the nuclear pore complex (NPC) have been shown to play a crucial role in protecting against replication stress, and recovery from some types of stalled or collapsed replication forks requires movement of the DNA to the NPC in order to maintain genome stability. The role that nuclear positioning has on DNA repair has been investigated in several systems that inhibit normal replication. These include structure forming sequences (expanded CAG repeats), protein mediated stalls (replication fork barriers (RFBs)), stalls within the telomere sequence, and the use of drugs known to stall or collapse replication forks (HU + MMS or aphidicolin). Recently, the mechanism of relocation for collapsed replication forks to the NPC has been elucidated. Here, we will review the types of replication stress that relocate to the NPC, the current models for the mechanism of relocation, and the currently known protective effects of this movement.
Collapse
Affiliation(s)
- Jenna M. Whalen
- Department of Biology, Tufts University, Medford, MA 02155, USA;
| | - Catherine H. Freudenreich
- Department of Biology, Tufts University, Medford, MA 02155, USA;
- Program in Genetics, Tufts University, Boston, MA 02111, USA
| |
Collapse
|
3
|
Liu C, Zhao H, Xiao S, Han T, Chen Y, Wang T, Ma Y, Gao H, Xie Z, Du L, Li J, Li G, Li W. Slx5p-Slx8p Promotes Accurate Chromosome Segregation by Mediating the Degradation of Synaptonemal Complex Components during Meiosis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1900739. [PMID: 32099749 PMCID: PMC7029635 DOI: 10.1002/advs.201900739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 12/08/2019] [Indexed: 06/10/2023]
Abstract
Meiosis increases genetic diversity, yet the genome complement needs to be stable to ensure offspring viability. Both small ubiquitin-like modifier (SUMO) and ubiquitin have been reported to participate in meiotic regulation, yet functions of the SUMO-ubiquitination crosstalk in meiosis remain unclear. Here, it is reported that a SUMO-targeted ubiquitin ligase, Slx8p, promotes accurate chromosome segregation during meiosis, since the deletion of SLX8 leads to increased aneuploidy due to a defect in synaptonemal complex (SC) component degradation. Both the RING domain and SUMO interacting motifs of Slx8p are essential for meiotic progression and maintaining spore viability, and the expression of tetraubiquitin fused with SUMO partially rescues meiotic defects in the SLX8-deletion strain. Furthermore, Slx5p-Slx8p can directly add ubiquitin to SUMOylated Zip1p and Ecm11p, and forced degradation of Ecm11p partially rescues the sporulation defects of the SLX8 deletion strain. These findings provide a mechanism for SC disassembly and reveal that the crosstalk between SUMOylation and ubiquitination facilitates accurate chromosome segregation by promoting SC component degradation during meiosis.
Collapse
Affiliation(s)
- Chao Liu
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
| | - Haichao Zhao
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Sai Xiao
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Tingting Han
- The Key Laboratory of GeriatricsBeijing Institute of GeriatricsBeijing HospitalNational Center of GerontologyNational Health CommissionInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijing100730P. R. China
| | - Yinghong Chen
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Tong Wang
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
| | - Yanjie Ma
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Hui Gao
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
| | - Zhiping Xie
- Joint International Research Laboratory of Metabolic & Developmental SciencesSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghai200240P. R. China
| | - Li‐Lin Du
- National Institute of Biological SciencesBeijing102206P. R. China
| | - Jian Li
- The Key Laboratory of GeriatricsBeijing Institute of GeriatricsBeijing HospitalNational Center of GerontologyNational Health CommissionInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijing100730P. R. China
| | - Guoping Li
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
- The Key Laboratory of GeriatricsBeijing Institute of GeriatricsBeijing HospitalNational Center of GerontologyNational Health CommissionInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijing100730P. R. China
| | - Wei Li
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of ZoologyChinese Academy of SciencesBeijing100101P. R. China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| |
Collapse
|
4
|
Lian J, Schultz C, Cao M, HamediRad M, Zhao H. Multi-functional genome-wide CRISPR system for high throughput genotype-phenotype mapping. Nat Commun 2019; 10:5794. [PMID: 31857575 PMCID: PMC6923430 DOI: 10.1038/s41467-019-13621-4] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 11/12/2019] [Indexed: 01/20/2023] Open
Abstract
Genome-scale engineering is an indispensable tool to understand genome functions due to our limited knowledge of cellular networks. Unfortunately, most existing methods for genome-wide genotype–phenotype mapping are limited to a single mode of genomic alteration, i.e. overexpression, repression, or deletion. Here we report a multi-functional genome-wide CRISPR (MAGIC) system to precisely control the expression level of defined genes to desired levels throughout the whole genome. By combining the tri-functional CRISPR system and array-synthesized oligo pools, MAGIC is used to create, to the best of our knowledge, one of the most comprehensive and diversified genomic libraries in yeast ever reported. The power of MAGIC is demonstrated by the identification of previously uncharacterized genetic determinants of complex phenotypes, particularly those having synergistic interactions when perturbed to different expression levels. MAGIC represents a powerful synthetic biology tool to investigate fundamental biological questions as well as engineer complex phenotypes for biotechnological applications. Genome-scale engineering is generally limited to single methods of alteration such as overexpression, repression or deletion. Here the authors present a tri-functional CRISPR system that can engineer complex synergistic interactions in a genome-wide manner.
Collapse
Affiliation(s)
- Jiazhang Lian
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, 310027, Hangzhou, China
| | - Carl Schultz
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Mingfeng Cao
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Mohammad HamediRad
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Lifefoundry Inc., 60 Hazelwood Dr., Champaign, IL, 61820, USA
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Departments of Chemistry, Biochemistry, and Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| |
Collapse
|
5
|
Kumar R, Sabapathy K. RNF4—A Paradigm for SUMOylation‐Mediated Ubiquitination. Proteomics 2019; 19:e1900185. [DOI: 10.1002/pmic.201900185] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/13/2019] [Indexed: 01/08/2023]
Affiliation(s)
- Ramesh Kumar
- Cancer & Stem Cell Biology Program Duke–NUS Medical School 8 College Road Singapore 169857 Singapore
| | - Kanaga Sabapathy
- Cancer & Stem Cell Biology Program Duke–NUS Medical School 8 College Road Singapore 169857 Singapore
- Laboratory of Molecular Carcinogenesis Division of Cellular & Molecular Research Humphrey Oei Institute of Cancer Research National Cancer Centre Singapore 11 Hospital Drive Singapore 169610 Singapore
- Department of Biochemistry National University of Singapore 8 Medical Drive Singapore 117597 Singapore
- Institute of Molecular and Cellular Biology 61 Biopolis Drive Singapore 138673 Singapore
| |
Collapse
|
6
|
Psakhye I, Castellucci F, Branzei D. SUMO-Chain-Regulated Proteasomal Degradation Timing Exemplified in DNA Replication Initiation. Mol Cell 2019; 76:632-645.e6. [PMID: 31519521 PMCID: PMC6891891 DOI: 10.1016/j.molcel.2019.08.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/01/2019] [Accepted: 08/01/2019] [Indexed: 11/18/2022]
Abstract
Similar to ubiquitin, SUMO forms chains, but the identity of SUMO-chain-modified factors and the purpose of this modification remain largely unknown. Here, we identify the budding yeast SUMO protease Ulp2, able to disassemble SUMO chains, as a DDK interactor enriched at replication origins that promotes DNA replication initiation. Replication-engaged DDK is SUMOylated on chromatin, becoming a degradation-prone substrate when Ulp2 no longer protects it against SUMO chain assembly. Specifically, SUMO chains channel DDK for SUMO-targeted ubiquitin ligase Slx5/Slx8-mediated and Cdc48 segregase-assisted proteasomal degradation. Importantly, the SUMOylation-defective ddk-KR mutant rescues inefficient replication onset and MCM activation in cells lacking Ulp2, suggesting that SUMO chains time DDK degradation. Using two unbiased proteomic approaches, we further identify subunits of the MCM helicase and other factors as SUMO-chain-modified degradation-prone substrates of Ulp2 and Slx5/Slx8. We thus propose SUMO-chain/Ulp2-protease-regulated proteasomal degradation as a mechanism that times the availability of functionally engaged SUMO-modified protein pools during replication and beyond.
Collapse
Affiliation(s)
- Ivan Psakhye
- IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | | | - Dana Branzei
- IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100 Pavia, Italy.
| |
Collapse
|
7
|
Talhaoui I, Bernal M, Mullen JR, Dorison H, Palancade B, Brill SJ, Mazón G. Slx5-Slx8 ubiquitin ligase targets active pools of the Yen1 nuclease to limit crossover formation. Nat Commun 2018; 9:5016. [PMID: 30479332 PMCID: PMC6258734 DOI: 10.1038/s41467-018-07364-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 10/01/2018] [Indexed: 12/17/2022] Open
Abstract
The repair of double-stranded DNA breaks (DSBs) by homologous recombination involves the formation of branched intermediates that can lead to crossovers following nucleolytic resolution. The nucleases Mus81-Mms4 and Yen1 are tightly controlled during the cell cycle to limit the extent of crossover formation and preserve genome integrity. Here we show that Yen1 is further regulated by sumoylation and ubiquitination. In vivo, Yen1 becomes sumoylated under conditions of DNA damage by the redundant activities of Siz1 and Siz2 SUMO ligases. Yen1 is also a substrate of the Slx5-Slx8 ubiquitin ligase. Loss of Slx5-Slx8 stabilizes the sumoylated fraction, attenuates Yen1 degradation at the G1/S transition, and results in persistent localization of Yen1 in nuclear foci. Slx5-Slx8-dependent ubiquitination of Yen1 occurs mainly at K714 and mutation of this lysine increases crossover formation during DSB repair and suppresses chromosome segregation defects in a mus81∆ background. Nucleases are regulated during the cell cycle to control for crossover formation and maintain genome integrity. Here the authors reveal that the yeast Holliday junction resolvase Yen is a sumoylation target and it is regulated by the ubiquitin ligases Slx5/Slx8 during crossover formation.
Collapse
Affiliation(s)
- Ibtissam Talhaoui
- CNRS UMR 8200, Université Paris-Sud - Université Paris-Saclay, Gustave Roussy, 114 rue Édouard Vaillant, 94800, Villejuif, France
| | - Manuel Bernal
- CNRS UMR 8200, Université Paris-Sud - Université Paris-Saclay, Gustave Roussy, 114 rue Édouard Vaillant, 94800, Villejuif, France
| | - Janet R Mullen
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, 08854, USA
| | - Hugo Dorison
- CNRS UMR 8200, Université Paris-Sud - Université Paris-Saclay, Gustave Roussy, 114 rue Édouard Vaillant, 94800, Villejuif, France
| | - Benoit Palancade
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 15 rue Hélène Brion, 75013, Paris, France
| | - Steven J Brill
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, 08854, USA
| | - Gerard Mazón
- CNRS UMR 8200, Université Paris-Sud - Université Paris-Saclay, Gustave Roussy, 114 rue Édouard Vaillant, 94800, Villejuif, France.
| |
Collapse
|
8
|
Localization and Regulation of the T1 Unimolecular Spanin. J Virol 2018; 92:JVI.00380-18. [PMID: 30135120 DOI: 10.1128/jvi.00380-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/01/2018] [Indexed: 11/20/2022] Open
Abstract
Spanins are bacteriophage lysis proteins responsible for disruption of the outer membrane, the final step of Gram-negative host lysis. The absence of spanins results in a terminal phenotype of fragile spherical cells. The phage T1 employs a unimolecular spanin gp11 that has an N-terminal lipoylation signal and a C-terminal transmembrane domain. Upon maturation and localization, gp11 ends up as an outer membrane lipoprotein with a C-terminal transmembrane domain embedded in the inner membrane, thus connecting both membranes as a covalent polypeptide chain. Unlike the two-component spanins encoded by most of the other phages, including lambda, the unimolecular spanins have not been studied extensively. In this work, we show that the gp11 mutants lacking either membrane localization signal were nonfunctional and conferred a partially dominant phenotype. Translation from internal start sites within the gp11 coding sequence generated a shorter product which exhibited a negative regulatory effect on gp11 function. Fluorescence spectroscopy time-lapse videos of gp11-GFP expression showed gp11 accumulated in distinct punctate foci, suggesting localized clusters assembled within the peptidoglycan meshwork. In addition, gp11 was shown to mediate lysis in the absence of holin and endolysin function when peptidoglycan density was depleted by starvation for murein precursors. This result indicates that the peptidoglycan is a negative regulator of gp11 function. This supports a model in which gp11 acts by fusing the inner and outer membranes, a mode of action analogous to but mechanistically distinct from that proposed for the two-component spanin systems.IMPORTANCE Spanins have been proposed to fuse the cytoplasmic and outer membranes during phage lysis. Recent work with the lambda spanins Rz-Rz1, which are similar to class I viral fusion proteins, has shed light on the functional domains and requirements for two-component spanin function. Here we report, for the first time, a genetic and biochemical approach to characterize unimolecular spanins, which are structurally and mechanistically different from two-component spanins. Considering similar predicted secondary structures within the ectodomains, unimolecular spanins can be regarded as a prokaryotic version of type II viral membrane fusion proteins. This study not only adds to our understanding of regulation of phage lysis at various levels but also provides a prokaryotic genetically tractable platform for interrogating class II-like membrane fusion proteins.
Collapse
|
9
|
Nguyen H, Labella S, Silva N, Jantsch V, Zetka M. C. elegans ZHP-4 is required at multiple distinct steps in the formation of crossovers and their transition to segregation competent chiasmata. PLoS Genet 2018; 14:e1007776. [PMID: 30379819 PMCID: PMC6239344 DOI: 10.1371/journal.pgen.1007776] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 11/16/2018] [Accepted: 10/17/2018] [Indexed: 12/31/2022] Open
Abstract
Correct segregation of meiotic chromosomes depends on DNA crossovers (COs) between homologs that culminate into visible physical linkages called chiasmata. COs emerge from a larger population of joint molecules (JM), the remainder of which are repaired as noncrossovers (NCOs) to restore genomic integrity. We present evidence that the RNF212-like C. elegans protein ZHP-4 cooperates with its paralog ZHP-3 to enforce crossover formation at distinct steps during meiotic prophase: in the formation of early JMs and in transition of late CO intermediates into chiasmata. ZHP-3/4 localize to the synaptonemal complex (SC) co-dependently followed by their restriction to sites of designated COs. RING domain mutants revealed a critical function for ZHP-4 in localization of both proteins to the SC and for CO formation. While recombination initiates in zhp-4 mutants, they fail to appropriately acquire pro-crossover factors at abundant early JMs, indicating a function for ZHP-4 in an early step of the CO/NCO decision. At late pachytene stages, hypomorphic mutants exhibit significant levels of crossing over that are accompanied by defects in localization of pro-crossover RMH-1, MSH-5 and COSA-1 to designated crossover sites, and by the appearance of bivalents defective in chromosome remodelling required for segregation. These results reveal a ZHP-4 function at designated CO sites where it is required to stabilize pro-crossover factors at the late crossover intermediate, which in turn are required for the transition to a chiasma that is required for bivalent remodelling. Our study reveals an essential requirement for ZHP-4 in negotiating both the formation of COs and their ability to transition to structures capable of directing accurate chromosome segregation. We propose that ZHP-4 acts in concert with ZHP-3 to propel interhomolog JMs along the crossover pathway by stabilizing pro-CO factors that associate with early and late intermediates, thereby protecting designated crossovers as they transition into the chiasmata required for disjunction.
Collapse
Affiliation(s)
- Hanh Nguyen
- Department of Biology, McGill University, Montreal, Quebec Canada
| | - Sara Labella
- Department of Biology, McGill University, Montreal, Quebec Canada
| | - Nicola Silva
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Verena Jantsch
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Monique Zetka
- Department of Biology, McGill University, Montreal, Quebec Canada
| |
Collapse
|
10
|
Ohkuni K, Pasupala N, Peek J, Holloway GL, Sclar GD, Levy-Myers R, Baker RE, Basrai MA, Kerscher O. SUMO-Targeted Ubiquitin Ligases (STUbLs) Reduce the Toxicity and Abnormal Transcriptional Activity Associated With a Mutant, Aggregation-Prone Fragment of Huntingtin. Front Genet 2018; 9:379. [PMID: 30279700 PMCID: PMC6154015 DOI: 10.3389/fgene.2018.00379] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/27/2018] [Indexed: 01/01/2023] Open
Abstract
Cell viability and gene expression profiles are altered in cellular models of neurodegenerative disorders such as Huntington’s Disease (HD). Using the yeast model system, we show that the SUMO-targeted ubiquitin ligase (STUbL) Slx5 reduces the toxicity and abnormal transcriptional activity associated with a mutant, aggregation-prone fragment of huntingtin (Htt), the causative agent of HD. We demonstrate that expression of an aggregation-prone Htt construct with 103 glutamine residues (103Q), but not the non-expanded form (25Q), results in severe growth defects in slx5Δ and slx8Δ cells. Since Slx5 is a nuclear protein and because Htt expression affects gene transcription, we assessed the effect of STUbLs on the transcriptional properties of aggregation-prone Htt. Expression of Htt 25Q and 55Q fused to the Gal4 activation domain (AD) resulted in reporter gene auto-activation. Remarkably, the auto-activation of Htt constructs was abolished by expression of Slx5 fused to the Gal4 DNA-binding domain (BD-Slx5). In support of these observations, RNF4, the human ortholog of Slx5, curbs the aberrant transcriptional activity of aggregation-prone Htt in yeast and a variety of cultured human cell lines. Functionally, we find that an extra copy of SLX5 specifically reduces Htt aggregates in the cytosol as well as chromatin-associated Htt aggregates in the nucleus. Finally, using RNA sequencing, we identified and confirmed specific targets of Htt’s transcriptional activity that are modulated by Slx5. In summary, this study of STUbLs uncovers a conserved pathway that counteracts the accumulation of aggregating, transcriptionally active Htt (and possibly other poly-glutamine expanded proteins) on chromatin in both yeast and in mammalian cells.
Collapse
Affiliation(s)
- Kentaro Ohkuni
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Nagesh Pasupala
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | - Jennifer Peek
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | | | - Gloria D Sclar
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | - Reuben Levy-Myers
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | - Richard E Baker
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, United States
| | - Munira A Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Oliver Kerscher
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| |
Collapse
|
11
|
Wang Z, Wu C, Aslanian A, Yates JR, Hunter T. Defective RNA polymerase III is negatively regulated by the SUMO-Ubiquitin-Cdc48 pathway. eLife 2018; 7:35447. [PMID: 30192228 PMCID: PMC6128692 DOI: 10.7554/elife.35447] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 08/21/2018] [Indexed: 12/26/2022] Open
Abstract
Transcription by RNA polymerase III (Pol III) is an essential cellular process, and mutations in Pol III can cause neurodegenerative disease in humans. However, in contrast to Pol II transcription, which has been extensively studied, the knowledge of how Pol III is regulated is very limited. We report here that in budding yeast, Saccharomyces cerevisiae, Pol III is negatively regulated by the Small Ubiquitin-like MOdifier (SUMO), an essential post-translational modification pathway. Besides sumoylation, Pol III is also targeted by ubiquitylation and the Cdc48/p97 segregase; these three processes likely act in a sequential manner and eventually lead to proteasomal degradation of Pol III subunits, thereby repressing Pol III transcription. This study not only uncovered a regulatory mechanism for Pol III, but also suggests that the SUMO and ubiquitin modification pathways and the Cdc48/p97 segregase can be potential therapeutic targets for Pol III-related human diseases.
Collapse
Affiliation(s)
- Zheng Wang
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
| | - Catherine Wu
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
| | - Aaron Aslanian
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, United States.,The Scripps Research Institute, La Jolla, United States
| | - John R Yates
- The Scripps Research Institute, La Jolla, United States
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
| |
Collapse
|
12
|
Zilio N, Eifler-Olivi K, Ulrich HD. Functions of SUMO in the Maintenance of Genome Stability. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 963:51-87. [PMID: 28197906 DOI: 10.1007/978-3-319-50044-7_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Like in most other areas of cellular metabolism, the functions of the ubiquitin-like modifier SUMO in the maintenance of genome stability are manifold and varied. Perturbations of global sumoylation causes a wide spectrum of phenotypes associated with defects in DNA maintenance, such as hypersensitivity to DNA-damaging agents, gross chromosomal rearrangements and loss of entire chromosomes. Consistent with these observations, many key factors involved in various DNA repair pathways have been identified as SUMO substrates. However, establishing a functional connection between a given SUMO target, the cognate SUMO ligase and a relevant phenotype has remained a challenge, mainly because of the difficulties involved in identifying important modification sites and downstream effectors that specifically recognize the target in its sumoylated state. This review will give an overview over the major pathways of DNA repair and genome maintenance influenced by the SUMO system and discuss selected examples of SUMO's actions in these pathways where the biological consequences of the modification have been elucidated.
Collapse
Affiliation(s)
- Nicola Zilio
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128, Mainz, Germany
| | | | - Helle D Ulrich
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128, Mainz, Germany.
| |
Collapse
|
13
|
A New Method, "Reverse Yeast Two-Hybrid Array" (RYTHA), Identifies Mutants that Dissociate the Physical Interaction Between Elg1 and Slx5. Genetics 2017; 206:1683-1697. [PMID: 28476868 DOI: 10.1534/genetics.117.200451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 04/27/2017] [Indexed: 11/18/2022] Open
Abstract
The vast majority of processes within the cell are carried out by proteins working in conjunction. The Yeast Two-Hybrid (Y2H) methodology allows the detection of physical interactions between any two interacting proteins. Here, we describe a novel systematic genetic methodology, "Reverse Yeast Two-Hybrid Array" (RYTHA), that allows the identification of proteins required for modulating the physical interaction between two given proteins. Our assay starts with a yeast strain in which the physical interaction of interest can be detected by growth on media lacking histidine, in the context of the Y2H methodology. By combining the synthetic genetic array technology, we can systematically screen mutant libraries of the yeast Saccharomyces cerevisiae to identify trans-acting mutations that disrupt the physical interaction of interest. We apply this novel method in a screen for mutants that disrupt the interaction between the N-terminus of Elg1 and the Slx5 protein. Elg1 is part of an alternative replication factor C-like complex that unloads PCNA during DNA replication and repair. Slx5 forms, together with Slx8, a SUMO-targeted ubiquitin ligase (STUbL) believed to send proteins to degradation. Our results show that the interaction requires both the STUbL activity and the PCNA unloading by Elg1, and identify topoisomerase I DNA-protein cross-links as a major factor in separating the two activities. Thus, we demonstrate that RYTHA can be applied to gain insights about particular pathways in yeast, by uncovering the connection between the proteasomal ubiquitin-dependent degradation pathway, DNA replication, and repair machinery, which can be separated by the topoisomerase-mediated cross-links to DNA.
Collapse
|
14
|
Monribot-Villanueva J, Zurita M, Vázquez M. Developmental transcriptional regulation by SUMOylation, an evolving field. Genesis 2017; 55. [PMID: 27935206 DOI: 10.1002/dvg.23009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 02/05/2023]
Abstract
SUMOylation is a reversible post-translational protein modification that affects the intracellular localization, stability, activity, and interactions of its protein targets. The SUMOylation pathway influences several nuclear and cytoplasmic processes. The expression of many genes, in particular those involved in development is finely tuned in space and time by several groups of proteins. There is growing evidence that transcriptional regulation mechanisms involve direct SUMOylation of transcriptional-related proteins such as initiation and elongation factors, and subunits of chromatin modifier and remodeling complexes originally described as members of the trithorax and Polycomb groups in Drosophila. Therefore, it is being unveiled that SUMOylation has a role in both, gene silencing and gene activation mechanisms. The goal of this review is to discuss the information on how SUMO modification in components of these multi-subunit complexes may have an effect in genome architecture and function and, therefore, in the regulation of gene expression in time and space.
Collapse
Affiliation(s)
- Juan Monribot-Villanueva
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Mario Zurita
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Martha Vázquez
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| |
Collapse
|
15
|
Newman HA, Meluh PB, Lu J, Vidal J, Carson C, Lagesse E, Gray JJ, Boeke JD, Matunis MJ. A high throughput mutagenic analysis of yeast sumo structure and function. PLoS Genet 2017; 13:e1006612. [PMID: 28166236 PMCID: PMC5319795 DOI: 10.1371/journal.pgen.1006612] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 02/21/2017] [Accepted: 01/31/2017] [Indexed: 11/18/2022] Open
Abstract
Sumoylation regulates a wide range of essential cellular functions through diverse mechanisms that remain to be fully understood. Using S. cerevisiae, a model organism with a single essential SUMO gene (SMT3), we developed a library of >250 mutant strains with single or multiple amino acid substitutions of surface or core residues in the Smt3 protein. By screening this library using plate-based assays, we have generated a comprehensive structure-function based map of Smt3, revealing essential amino acid residues and residues critical for function under a variety of genotoxic and proteotoxic stress conditions. Functionally important residues mapped to surfaces affecting Smt3 precursor processing and deconjugation from protein substrates, covalent conjugation to protein substrates, and non-covalent interactions with E3 ligases and downstream effector proteins containing SUMO-interacting motifs. Lysine residues potentially involved in formation of polymeric chains were also investigated, revealing critical roles for polymeric chains, but redundancy in specific chain linkages. Collectively, our findings provide important insights into the molecular basis of signaling through sumoylation. Moreover, the library of Smt3 mutants represents a valuable resource for further exploring the functions of sumoylation in cellular stress response and other SUMO-dependent pathways.
Collapse
Affiliation(s)
- Heather A. Newman
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Pamela B. Meluh
- High Throughput Biology Center and Department of Molecular Biology and Genetics, Johns Hopkins University, School of Medicine, Baltimore, MD, United States of America
| | - Jian Lu
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Jeremy Vidal
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Caryn Carson
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Elizabeth Lagesse
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, United States of America
| | - Jeffrey J. Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, United States of America
| | - Jef D. Boeke
- High Throughput Biology Center and Department of Molecular Biology and Genetics, Johns Hopkins University, School of Medicine, Baltimore, MD, United States of America
| | - Michael J. Matunis
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD, United States of America
| |
Collapse
|
16
|
The Molecular Interface Between the SUMO and Ubiquitin Systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 963:99-110. [DOI: 10.1007/978-3-319-50044-7_6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
17
|
Boomsma W, Nielsen SV, Lindorff-Larsen K, Hartmann-Petersen R, Ellgaard L. Bioinformatics analysis identifies several intrinsically disordered human E3 ubiquitin-protein ligases. PeerJ 2016; 4:e1725. [PMID: 26966660 PMCID: PMC4782732 DOI: 10.7717/peerj.1725] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/02/2016] [Indexed: 12/28/2022] Open
Abstract
The ubiquitin-proteasome system targets misfolded proteins for degradation. Since the accumulation of such proteins is potentially harmful for the cell, their prompt removal is important. E3 ubiquitin-protein ligases mediate substrate ubiquitination by bringing together the substrate with an E2 ubiquitin-conjugating enzyme, which transfers ubiquitin to the substrate. For misfolded proteins, substrate recognition is generally delegated to molecular chaperones that subsequently interact with specific E3 ligases. An important exception is San1, a yeast E3 ligase. San1 harbors extensive regions of intrinsic disorder, which provide both conformational flexibility and sites for direct recognition of misfolded targets of vastly different conformations. So far, no mammalian ortholog of San1 is known, nor is it clear whether other E3 ligases utilize disordered regions for substrate recognition. Here, we conduct a bioinformatics analysis to examine >600 human and S. cerevisiae E3 ligases to identify enzymes that are similar to San1 in terms of function and/or mechanism of substrate recognition. An initial sequence-based database search was found to detect candidates primarily based on the homology of their ordered regions, and did not capture the unique disorder patterns that encode the functional mechanism of San1. However, by searching specifically for key features of the San1 sequence, such as long regions of intrinsic disorder embedded with short stretches predicted to be suitable for substrate interaction, we identified several E3 ligases with these characteristics. Our initial analysis revealed that another remarkable trait of San1 is shared with several candidate E3 ligases: long stretches of complete lysine suppression, which in San1 limits auto-ubiquitination. We encode these characteristic features into a San1 similarity-score, and present a set of proteins that are plausible candidates as San1 counterparts in humans. In conclusion, our work indicates that San1 is not a unique case, and that several other yeast and human E3 ligases have sequence properties that may allow them to recognize substrates by a similar mechanism as San1.
Collapse
Affiliation(s)
- Wouter Boomsma
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Sofie V Nielsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Kresten Lindorff-Larsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Rasmus Hartmann-Petersen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Lars Ellgaard
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| |
Collapse
|
18
|
Wang M, Sang J, Ren Y, Liu K, Liu X, Zhang J, Wang H, Wang J, Orian A, Yang J, Yi J. SENP3 regulates the global protein turnover and the Sp1 level via antagonizing SUMO2/3-targeted ubiquitination and degradation. Protein Cell 2016; 7:63-77. [PMID: 26511642 PMCID: PMC4707158 DOI: 10.1007/s13238-015-0216-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 09/08/2015] [Indexed: 12/19/2022] Open
Abstract
SUMOylation is recently found to function as a targeting signal for the degradation of substrates through the ubiquitin-proteasome system. RNF4 is the most studied human SUMO-targeted ubiquitin E3 ligase. However, the relationship between SUMO proteases, SENPs, and RNF4 remains obscure. There are limited examples of the SENP regulation of SUMO2/3-targeted proteolysis mediated by RNF4. The present study investigated the role of SENP3 in the global protein turnover related to SUMO2/3-targeted ubiquitination and focused in particular on the SENP3 regulation of the stability of Sp1. Our data demonstrated that SENP3 impaired the global ubiquitination profile and promoted the accumulation of many proteins. Sp1, a cancer-associated transcription factor, was among these proteins. SENP3 increased the level of Sp1 protein via antagonizing the SUMO2/3-targeted ubiquitination and the consequent proteasome-dependent degradation that was mediated by RNF4. De-conjugation of SUMO2/3 by SENP3 attenuated the interaction of Sp1 with RNF4. In gastric cancer cell lines and specimens derived from patients and nude mice, the level of Sp1 was generally increased in parallel to the level of SENP3. These results provided a new explanation for the enrichment of the Sp1 protein in various cancers, and revealed a regulation of SUMO2/3 conjugated proteins whose levels may be tightly controlled by SENP3 and RNF4.
Collapse
Affiliation(s)
- Ming Wang
- Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jing Sang
- Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yanhua Ren
- Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Kejia Liu
- Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xinyi Liu
- Department of Pathophysiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jian Zhang
- Department of Pathophysiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Haolu Wang
- Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Jian Wang
- Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Amir Orian
- Faculty of Medicine, Cancer and Vascular Biology Research Center, Technion-Israel Institute of Technology, Haifa, 31096, Israel
| | - Jie Yang
- Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Jing Yi
- Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| |
Collapse
|
19
|
Nielsen SV, Poulsen EG, Rebula CA, Hartmann-Petersen R. Protein quality control in the nucleus. Biomolecules 2014; 4:646-61. [PMID: 25010148 PMCID: PMC4192666 DOI: 10.3390/biom4030646] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/20/2014] [Accepted: 06/04/2014] [Indexed: 01/18/2023] Open
Abstract
In their natural environment, cells are regularly exposed to various stress conditions that may lead to protein misfolding, but also in the absence of stress, misfolded proteins occur as the result of mutations or failures during protein synthesis. Since such partially denatured proteins are prone to aggregate, cells have evolved several elaborate quality control systems to deal with these potentially toxic proteins. First, various molecular chaperones will seize the misfolded protein and either attempt to refold the protein or target it for degradation via the ubiquitin-proteasome system. The degradation of misfolded proteins is clearly compartmentalized, so unique degradation pathways exist for misfolded proteins depending on whether their subcellular localization is ER/secretory, mitochondrial, cytosolic or nuclear. Recent studies, mainly in yeast, have shown that the nucleus appears to be particularly active in protein quality control. Thus, specific ubiquitin-protein ligases located in the nucleus, target not only misfolded nuclear proteins, but also various misfolded cytosolic proteins which are transported to the nucleus prior to their degradation. In comparison, much less is known about these mechanisms in mammalian cells. Here we highlight recent advances in our understanding of nuclear protein quality control, in particular regarding substrate recognition and proteasomal degradation.
Collapse
Affiliation(s)
- Sofie V Nielsen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Esben G Poulsen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Caio A Rebula
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Rasmus Hartmann-Petersen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| |
Collapse
|
20
|
Westerbeck JW, Pasupala N, Guillotte M, Szymanski E, Matson BC, Esteban C, Kerscher O. A SUMO-targeted ubiquitin ligase is involved in the degradation of the nuclear pool of the SUMO E3 ligase Siz1. Mol Biol Cell 2013; 25:1-16. [PMID: 24196836 PMCID: PMC3873881 DOI: 10.1091/mbc.e13-05-0291] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Here we show that the Slx5/Slx8 STUbL complex is involved in the efficient degradation of the nuclear pool of Siz1, a SUMO E3 ligase with many nuclear and cytosolic substrates. This novel finding suggests that STUbLs can regulate cellular SUMO homeostasis by targeting SUMO E3 ligases. The Slx5/Slx8 heterodimer constitutes a SUMO-targeted ubiquitin ligase (STUbL) with an important role in SUMO-targeted degradation and SUMO-dependent signaling. This STUbL relies on SUMO-interacting motifs in Slx5 to aid in substrate targeting and carboxy-terminal RING domains in both Slx5 and Slx8 for substrate ubiquitylation. In budding yeast cells, Slx5 resides in the nucleus, forms distinct foci, and can associate with double-stranded DNA breaks. However, it remains unclear how STUbLs interact with other proteins and their substrates. To examine the targeting and functions of the Slx5/Slx8 STUbL, we constructed and analyzed truncations of the Slx5 protein. Our structure–function analysis reveals a domain of Slx5 involved in nuclear localization and in the interaction with Slx5, SUMO, Slx8, and a novel interactor, the SUMO E3 ligase Siz1. We further analyzed the functional interaction of Slx5 and Siz1 in vitro and in vivo. We found that a recombinant Siz1 fragment is an in vitro ubiquitylation target of the Slx5/Slx8 STUbL. Furthermore, slx5∆ cells accumulate phosphorylated and sumoylated adducts of Siz1 in vivo. Specifically, we show that Siz1 can be ubiquitylated in vivo and is degraded in an Slx5-dependent manner when its nuclear egress is prevented in mitosis. In conclusion, our data provide a first look into the STUbL-mediated regulation of a SUMO E3 ligase.
Collapse
Affiliation(s)
- Jason W Westerbeck
- Biology Department, The College of William & Mary, Williamsburg, VA 23187
| | | | | | | | | | | | | |
Collapse
|
21
|
SUMO-targeted ubiquitin ligases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:75-85. [PMID: 24018209 DOI: 10.1016/j.bbamcr.2013.08.022] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/25/2013] [Accepted: 08/28/2013] [Indexed: 12/16/2022]
Abstract
Covalent posttranslational modification with SUMO (small ubiquitin-related modifier) modulates functions of a wide range of proteins in eukaryotic cells. Sumoylation affects the activity, interaction properties, subcellular localization and the stability of its substrate proteins. The recent discovery of a novel class of ubiquitin ligases (E3), termed ULS (E3-S) or STUbL, that recognize sumoylated proteins, links SUMO modification to the ubiquitin/proteasome system. Here we review recent insights into the properties and function of these ligases and their roles in regulating sumoylated proteins. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
Collapse
|
22
|
Srikumar T, Lewicki MC, Costanzo M, Tkach JM, van Bakel H, Tsui K, Johnson ES, Brown GW, Andrews BJ, Boone C, Giaever G, Nislow C, Raught B. Global analysis of SUMO chain function reveals multiple roles in chromatin regulation. ACTA ACUST UNITED AC 2013; 201:145-63. [PMID: 23547032 PMCID: PMC3613684 DOI: 10.1083/jcb.201210019] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Multiple large-scale analyses in yeast implicate SUMO chain function in the
maintenance of higher-order chromatin structure and transcriptional repression
of environmental stress response genes. Like ubiquitin, the small ubiquitin-related modifier (SUMO) proteins can form
oligomeric “chains,” but the biological functions of these
superstructures are not well understood. Here, we created mutant yeast strains
unable to synthesize SUMO chains (smt3allR) and
subjected them to high-content microscopic screening, synthetic genetic array
(SGA) analysis, and high-density transcript profiling to perform the first
global analysis of SUMO chain function. This comprehensive assessment identified
144 proteins with altered localization or intensity in
smt3allR cells, 149 synthetic genetic
interactions, and 225 mRNA transcripts (primarily consisting of stress- and
nutrient-response genes) that displayed a >1.5-fold increase in
expression levels. This information-rich resource strongly implicates SUMO
chains in the regulation of chromatin. Indeed, using several different
approaches, we demonstrate that SUMO chains are required for the maintenance of
normal higher-order chromatin structure and transcriptional repression of
environmental stress response genes in budding yeast.
Collapse
Affiliation(s)
- Tharan Srikumar
- Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Physical and Genetic Interactions Between Uls1 and the Slx5-Slx8 SUMO-Targeted Ubiquitin Ligase. G3-GENES GENOMES GENETICS 2013; 3:771-780. [PMID: 23550137 PMCID: PMC3618364 DOI: 10.1534/g3.113.005827] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Slx5-Slx8 complex is a ubiquitin ligase that preferentially ubiquitylates SUMOylated substrates, targeting them for proteolysis. Mutations in SLX5, SLX8, and other SUMO pathway genes were previously identified in our laboratory as genomic suppressors of a point mutation (mot1-301) in the transcriptional regulator MOT1 To further understand the links between the SUMO and ubiquitin pathways, a screen was performed for high-copy suppressors of mot1-301, yielding three genes (MOT3, MIT1, and ULS1). MOT3 and MIT1 have characteristics of prions, and ULS1 is believed to encode another SUMO-targeted ubiquitin ligase (STUbL) that functionally overlaps with Slx5-Slx8. Here we focus on ULS1, obtaining results suggesting that the relationship between ULS1 and SLX5 is more complex than expected. Uls1 interacted with Slx5 physically in to yeast two-hybrid and co-immunoprecipitation assays, a uls1 mutation that blocked the interaction between Uls1 and Slx5 interfered with ULS1 function, and genetic analyses indicated an antagonistic relationship between ULS1 and SLX5 Combined, our results challenge the assumption that Uls1 and Slx5 are simply partially overlapping STUbLs and begin to illuminate a regulatory relationship between these two proteins.
Collapse
|
24
|
Arkadia, a novel SUMO-targeted ubiquitin ligase involved in PML degradation. Mol Cell Biol 2013; 33:2163-77. [PMID: 23530056 DOI: 10.1128/mcb.01019-12] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Arkadia is a RING domain E3 ubiquitin ligase that activates the transforming growth factor β (TGF-β) pathway by inducing degradation of the inhibitor SnoN/Ski. Here we show that Arkadia contains three successive SUMO-interacting motifs (SIMs) that mediate noncovalent interaction with poly-SUMO2. We identify the third SIM (VVDL) of Arkadia to be the most relevant one in this interaction. Furthermore, we provide evidence that Arkadia can function as a SUMO-targeted ubiquitin ligase (STUBL) by ubiquitinating SUMO chains. While the SIMs of Arkadia are not essential for SnoN/Ski degradation in response to TGF-β, we show that they are necessary for the interaction of Arkadia with polysumoylated PML in response to arsenic and its concomitant accumulation into PML nuclear bodies. Moreover, Arkadia depletion leads to accumulation of polysumoylated PML in response to arsenic, highlighting a requirement of Arkadia for arsenic-induced degradation of polysumoylated PML. Interestingly, Arkadia homodimerizes but does not heterodimerize with RNF4, the other STUBL involved in PML degradation, suggesting that these two E3 ligases do not act synergistically but most probably act independently during this process. Altogether, these results identify Arkadia to be a novel STUBL that can trigger degradation of signal-induced polysumoylated proteins.
Collapse
|
25
|
Hickey CM, Wilson NR, Hochstrasser M. Function and regulation of SUMO proteases. Nat Rev Mol Cell Biol 2013; 13:755-66. [PMID: 23175280 DOI: 10.1038/nrm3478] [Citation(s) in RCA: 478] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Covalent attachment of small ubiquitin-like modifier (SUMO) to proteins is highly dynamic, and both SUMO-protein conjugation and cleavage can be regulated. Protein desumoylation is carried out by SUMO proteases, which control cellular mechanisms ranging from transcription and cell division to ribosome biogenesis. Recent advances include the discovery of two novel classes of SUMO proteases, insights regarding SUMO protease specificity, and revelations of previously unappreciated SUMO protease functions in several key cellular pathways. These developments, together with new connections between SUMO proteases and the recently discovered SUMO-targeted ubiquitin ligases (STUbLs), make this an exciting period to study these enzymes.
Collapse
Affiliation(s)
- Christopher M Hickey
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06520, USA
| | | | | |
Collapse
|
26
|
Watts FZ, Hoffmann E. SUMO meets meiosis: an encounter at the synaptonemal complex: SUMO chains and sumoylated proteins suggest that heterogeneous and complex interactions lie at the centre of the synaptonemal complex. Bioessays 2011; 33:529-37. [PMID: 21590786 DOI: 10.1002/bies.201100002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent discoveries have identified the small ubiquitin-like modifier (SUMO) as the potential 'missing link' that could explain how the synaptonemal complex (SC) is formed during meiosis. The SC is important for a variety of chromosome interactions during meiosis and appears ladder-like. It is formed when 'axes' of the two homologous chromosomes become connected by the deposition of transverse filaments, forming the steps of the ladder. Although several components of axial and transverse elements have been identified, how the two are connected to form the SC has remained an enigma. Recent discoveries suggest that SUMO modification underlies protein-protein interactions within the SC of budding yeast. The versatility of SUMO in regulating protein-protein interactions adds an exciting new dimension to our understanding of the SC and suggests that SCs are not homogenous structures throughout the nucleus. We propose that this heterogeneity may allow differential regulation of chromosome structure and function.
Collapse
Affiliation(s)
- Felicity Z Watts
- MRC Genome Damage and Stability Centre, University of Sussex, Falmer, UK.
| | | |
Collapse
|
27
|
Fredrickson EK, Rosenbaum JC, Locke MN, Milac TI, Gardner RG. Exposed hydrophobicity is a key determinant of nuclear quality control degradation. Mol Biol Cell 2011; 22:2384-95. [PMID: 21551067 PMCID: PMC3128539 DOI: 10.1091/mbc.e11-03-0256] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Protein quality control (PQC) degradation protects the cell by preventing the toxic accumulation of misfolded proteins. In eukaryotes, PQC degradation is primarily achieved by ubiquitin ligases that attach ubiquitin to misfolded proteins for proteasome degradation. To function effectively, PQC ubiquitin ligases must distinguish misfolded proteins from their normal counterparts by recognizing an attribute of structural abnormality commonly shared among misfolded proteins. However, the nature of the structurally abnormal feature recognized by most PQC ubiquitin ligases is unknown. Here we demonstrate that the yeast nuclear PQC ubiquitin ligase San1 recognizes exposed hydrophobicity in its substrates. San1 recognition is triggered by exposure of as few as five contiguous hydrophobic residues, which defines the minimum window of hydrophobicity required for San1 targeting. We also find that the exposed hydrophobicity recognized by San1 can cause aggregation and cellular toxicity, underscoring the fundamental protective role for San1-mediated PQC degradation of misfolded nuclear proteins.
Collapse
Affiliation(s)
- Eric K Fredrickson
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | |
Collapse
|
28
|
Nagai S, Davoodi N, Gasser SM. Nuclear organization in genome stability: SUMO connections. Cell Res 2011; 21:474-85. [PMID: 21321608 DOI: 10.1038/cr.2011.31] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recent findings show that chromatin dynamics and nuclear organization are not only important for gene regulation and DNA replication, but also for the maintenance of genome stability. In yeast, nuclear pores play a role in the maintenance of genome stability by means of the evolutionarily conserved family of SUMO-targeted Ubiquitin ligases (STUbLs). The yeast Slx5/Slx8 STUbL associates with a class of DNA breaks that are shifted to nuclear pores. Functionally Slx5/Slx8 are needed for telomere maintenance by an unusual recombination-mediated pathway. The mammalian STUbL RNF4 associates with Promyelocytic leukaemia (PML) nuclear bodies and regulates PML/PML-fusion protein stability in response to arsenic-induced stress. A subclass of PML bodies support telomere maintenance by the ALT pathway in telomerase-deficient tumors. Perturbation of nuclear organization through either loss of pore subunits in yeast, or PML body perturbation in man, can lead to gene amplifications, deletions, translocations or end-to-end telomere fusion events, thus implicating SUMO and STUbLs in the subnuclear organization of select repair events.
Collapse
Affiliation(s)
- Shigeki Nagai
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | | | | |
Collapse
|
29
|
Genetic analysis implicates the Set3/Hos2 histone deacetylase in the deposition and remodeling of nucleosomes containing H2A.Z. Genetics 2011; 187:1053-66. [PMID: 21288874 DOI: 10.1534/genetics.110.125419] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Histone variants and histone modification complexes act to regulate the functions of chromatin. In Saccharomyces cerevisiae the histone variant H2A.Z is encoded by HTZ1. Htz1 is dispensable for viability in budding yeast, but htz1Δ is synthetic sick or lethal with the null alleles of about 200 nonessential genes. One of the strongest of these interactions is with the deletion of SET3, which encodes a subunit of the Set3/Hos2 histone deacetylase complex. Little is known about the functions of Set3, and interpreting these genetic interactions remains a highly challenging task. Here we report the results of a forward genetic screen to identify bypass suppressors of the synthetic slow-growth phenotype of htz1Δ set3Δ. Among the identified loss-of-function suppressors are genes encoding subunits of the HDA1 deacetylase complex, the SWR1 complex, the H2B deubiquitination module of SAGA, the proteasome, Set1, and Sir3. This constellation of suppressor genes is uncommon among the global set of htz1Δ synthetic interactions. BDF1, AHC1, RMR1, and CYC8 were identified as high-copy suppressors. We also identified interactions with SLX5 and SLX8, encoding the sumoylation-targeted ubiquitin ligase complex. In the context of htz1Δ set3Δ, suppressors in the SWR1 and the H2B deubiquitination complexes show strong functional similarity, as do suppressors in the silencing genes and the proteasome. Surprisingly, while both htz1Δ set3Δ and swr1Δ set3Δ have severe slow-growth phenotypes, the htz1Δ swr1Δ set3Δ triple mutant grows relatively well. We propose that Set3 has previously unrecognized functions in the dynamic deposition and remodeling of nucleosomes containing H2A.Z.
Collapse
|
30
|
Abstract
Saccharomyces cerevisiae cells lacking the Slx5-Slx8 SUMO-targeted Ub ligase display increased levels of sumoylated and polysumoylated proteins, and they are inviable in the absence of the Sgs1 DNA helicase. One explanation for this inviability is that one or more sumoylated proteins accumulate to toxic levels in sgs1Δ slx5Δ cells. To address this possibility, we isolated a second-site suppressor of sgs1Δ slx5Δ synthetic lethality and identified it as an allele of the ULP2 SUMO isopeptidase. The suppressor, ulp2-D623H, behaved like the ulp2Δ allele in its sensitivity to heat, DNA replication stress, and DNA damage. Surprisingly, deletion of ULP2, which is known to promote the accumulation of poly-SUMO chains, suppressed sgs1Δ slx5Δ synthetic lethality and the slx5Δ sporulation defect. Further, ulp2Δ's growth sensitivities were found to be suppressed in ulp2Δ slx5Δ double mutants. This mutual suppression indicates that SLX5-SLX8 and ULP2 interact antagonistically. However, the suppressed strain sgs1Δ slx5Δ ulp2-D623H displayed even higher levels of sumoylated proteins than the corresponding double mutants. Thus, sgs1Δ slx5Δ synthetic lethality cannot be due simply to high levels of bulk sumoylated proteins. We speculate that the loss of ULP2 suppresses the toxicity of the sumoylated proteins that accumulate in slx5Δ-slx8Δ cells by permitting the extension of poly-SUMO chains on specific target proteins. This additional modification might attenuate the activity of the target proteins or channel them into alternative pathways for proteolytic degradation. In support of this latter possibility we find that the WSS1 isopeptidase is required for suppression by ulp2Δ.
Collapse
|
31
|
Abstract
The budding yeast nucleus, like those of other eukaryotic species, is highly organized with respect to both chromosomal sequences and enzymatic activities. At the nuclear periphery interactions of nuclear pores with chromatin, mRNA, and transport factors promote efficient gene expression, whereas centromeres, telomeres, and silent chromatin are clustered and anchored away from pores. Internal nuclear organization appears to be function-dependent, reflecting localized sites for tRNA transcription, rDNA transcription, ribosome assembly, and DNA repair. Recent advances have identified new proteins involved in the positioning of chromatin and have allowed testing of the functional role of higher-order chromatin organization. The unequal distribution of silent information regulatory factors and histone modifying enzymes, which arises in part from the juxtaposition of telomeric repeats, has been shown to influence chromatin-mediated transcriptional repression. Other localization events suppress unwanted recombination. These findings highlight the contribution budding yeast genetics and cytology have made to dissecting the functional role of nuclear structure.
Collapse
Affiliation(s)
- Angela Taddei
- UMR 218, Centre National de la Recherche Scientifique, 26 rue d'Ulm, 75231 Paris Cedex 05, France
| | | | | |
Collapse
|
32
|
Wss1 is a SUMO-dependent isopeptidase that interacts genetically with the Slx5-Slx8 SUMO-targeted ubiquitin ligase. Mol Cell Biol 2010; 30:3737-48. [PMID: 20516210 DOI: 10.1128/mcb.01649-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Protein sumoylation plays an important but poorly understood role in controlling genome integrity. In Saccharomyces cerevisiae, the Slx5-Slx8 SUMO-targeted Ub ligase appears to be needed to ubiquitinate sumoylated proteins that arise in the absence of the Sgs1 DNA helicase. WSS1, a high-copy-number suppressor of a mutant SUMO, was implicated in this pathway because it shares phenotypes with SLX5-SLX8 mutants, including a wss1Delta sgs1Delta synthetic-fitness defect. Here we show that Wss1, a putative metalloprotease, physically binds SUMO and displays in vitro isopeptidase activity on poly-SUMO chains. Like that of SLX5, overexpression of WSS1 suppresses sgs1Delta slx5Delta lethality and the ulp1ts growth defect. Interestingly, although Wss1 is relatively inactive on ubiquitinated substrates and poly-Ub chains, it efficiently deubiquitinates a Ub-SUMO isopeptide conjugate and a Ub-SUMO fusion protein. Wss1 was further implicated in Ub metabolism on the basis of its physical association with proteasomal subunits. The results suggest that Wss1 is a SUMO-dependent isopeptidase that acts on sumoylated substrates as they undergo proteasomal degradation.
Collapse
|
33
|
Degradation of the Saccharomyces cerevisiae mating-type regulator alpha1: genetic dissection of cis-determinants and trans-acting pathways. Genetics 2010; 185:497-511. [PMID: 20351217 DOI: 10.1534/genetics.110.115907] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Mating phenotype in the yeast Saccharomyces cerevisiae is a dynamic trait, and efficient transitions between alternate haploid cell types allow the organism to access the advantageous diploid form. Mating identity is determined by cell type-specific transcriptional regulators, but these factors must be rapidly removed upon mating-type switching to allow the master regulators of the alternate state to establish a new gene expression program. Targeted proteolysis by the ubiquitin-proteasome system is a commonly employed strategy to quickly disassemble regulatory networks, and yeast use this approach to evoke efficient switching from the alpha to the a phenotype by ensuring the rapid removal of the alpha2 transcriptional repressor. Transition to the a cell phenotype, however, also requires the inactivation of the alpha1 transcriptional activator, but the mechanism by which this occurs is currently unknown. Here, we report a central role for the ubiquitin-proteasome system in alpha1 inactivation. The alpha1 protein is constitutively short lived and targeted for rapid turnover by multiple ubiquitin-conjugation pathways. Intriguingly, the alpha-domain, a conserved region of unknown function, acts as a degradation signal for a pathway defined by the SUMO-targeted ligase Slx5-Slx8, which has also been implicated in the rapid destruction of alpha2. Our observations suggest coordinate regulation in the turnover of two master regulatory transcription factors ensures a rapid mating-type switch.
Collapse
|
34
|
Miteva M, Keusekotten K, Hofmann K, Praefcke GJK, Dohmen RJ. Sumoylation as a signal for polyubiquitylation and proteasomal degradation. Subcell Biochem 2010; 54:195-214. [PMID: 21222284 DOI: 10.1007/978-1-4419-6676-6_16] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The small ubiquitin-related modifier (SUMO) is a versatile cellular tool to modulate a protein's function. SUMO modification is a reversible process analogous to ubiquitylation. The consecutive actions of E1, E2 and E3 enzymes catalyze the attachment of SUMO to target proteins, while deconjugation is promoted by SUMO specific proteases. Contrary to the long-standing assumption that SUMO has no role in proteolytic targeting and rather acts as an antagonist of ubiquitin in some cases, it has recently been discovered that sumoylation itself can function as a secondary signal mediating ubiquitin-dependent degradation by the proteasome. The discovery of a novel family of RING finger ubiquitin ligases bearing SUMO interaction motifs implicated the ubiquitin system in the control of SUMO modified proteins. SUMO modification as a signal for degradation is conserved in eukaryotes and ubiquitin ligases that specifically recognize SUMO-modified proteins have been discovered in species ranging from yeasts to humans. This chapter summarizes what is known about these ligases and their role in controlling sumoylated proteins.
Collapse
Affiliation(s)
- Maria Miteva
- Institute for Genetics, Cologne University, Zülpicher Straße 47, D- 50674, Cologne, Germany
| | | | | | | | | |
Collapse
|
35
|
Martin N, Schwamborn K, Schreiber V, Werner A, Guillier C, Zhang XD, Bischof O, Seeler JS, Dejean A. PARP-1 transcriptional activity is regulated by sumoylation upon heat shock. EMBO J 2009; 28:3534-48. [PMID: 19779455 DOI: 10.1038/emboj.2009.279] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 08/27/2009] [Indexed: 11/09/2022] Open
Abstract
Heat shock and other environmental stresses rapidly induce transcriptional responses subject to regulation by a variety of post-translational modifications. Among these, poly(ADP-ribosyl)ation and sumoylation have received growing attention. Here we show that the SUMO E3 ligase PIASy interacts with the poly(ADP-ribose) polymerase PARP-1, and that PIASy mediates heat shock-induced poly-sumoylation of PARP-1. Furthermore, PIASy, and hence sumoylation, appears indispensable for full activation of the inducible HSP70.1 gene. Chromatin immunoprecipitation experiments show that PIASy, SUMO and the SUMO-conjugating enzyme Ubc9 are rapidly recruited to the HSP70.1 promoter upon heat shock, and that they are subsequently released with kinetics similar to PARP-1. Finally, we provide evidence that the SUMO-targeted ubiquitin ligase RNF4 mediates heat-shock-inducible ubiquitination of PARP-1, regulates the stability of PARP-1, and, like PIASy, is a positive regulator of HSP70.1 gene activity. These results, thus, point to a novel mechanism for regulating PARP-1 transcription function, and suggest crosstalk between sumoylation and RNF4-mediated ubiquitination in regulating gene expression in response to heat shock.
Collapse
Affiliation(s)
- Nadine Martin
- Department of Cell Biology and Infection, Nuclear Organisation and Oncogenesis Unit, INSERM U579, Institut Pasteur, Paris, France
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Geoffroy MC, Hay RT. An additional role for SUMO in ubiquitin-mediated proteolysis. Nat Rev Mol Cell Biol 2009; 10:564-8. [PMID: 19474794 DOI: 10.1038/nrm2707] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Although the post-translational modification of proteins with small ubiquitin-like modifier (SUMO) has a role in many biological processes, it was thought that SUMO, unlike ubiquitin, does not target proteins for degradation. However, these views need to be revised, as recent findings in yeast and human cells indicate that SUMO can act as a signal for the recruitment of E3 ubiquitin ligases, which leads to the ubiquitylation and degradation of the modified protein.
Collapse
Affiliation(s)
- Marie-Claude Geoffroy
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK
| | | |
Collapse
|
37
|
Chen X, Ding B, LeJeune D, Ruggiero C, Li S. Rpb1 sumoylation in response to UV radiation or transcriptional impairment in yeast. PLoS One 2009; 4:e5267. [PMID: 19384408 PMCID: PMC2668072 DOI: 10.1371/journal.pone.0005267] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 03/24/2009] [Indexed: 11/18/2022] Open
Abstract
Covalent modifications of proteins by ubiquitin and the Small Ubiquitin-like MOdifier (SUMO) have been revealed to be involved in a plethora of cellular processes, including transcription, DNA repair and DNA damage responses. It has been well known that in response to DNA damage that blocks transcription elongation, Rpb1, the largest subunit of RNA polymerase II (Pol II), is ubiquitylated and subsequently degraded in mammalian and yeast cells. However, it is still an enigma regarding how Pol II responds to damaged DNA and conveys signal(s) for DNA damage-related cellular processes. We found that Rpb1 is also sumoylated in yeast cells upon UV radiation or impairment of transcription elongation, and this modification is independent of DNA damage checkpoint activation. Ubc9, an E2 SUMO conjugase, and Siz1, an E3 SUMO ligase, play important roles in Rpb1 sumoylation. K1487, which is located in the acidic linker region between the C-terminal domain and the globular domain of Rpb1, is the major sumoylation site. Rpb1 sumoylation is not affected by its ubiquitylation, and vice versa, indicating that the two processes do not crosstalk. Abolishment of Rpb1 sumoylation at K1487 does not affect transcription elongation or transcription coupled repair (TCR) of UV-induced DNA damage. However, deficiency in TCR enhances UV-induced Rpb1 sumoylation, presumably due to the persistence of transcription-blocking DNA lesions in the transcribed strand of a gene. Remarkably, abolishment of Rpb1 sumoylation at K1487 causes enhanced and prolonged UV-induced phosphorylation of Rad53, especially in TCR-deficient cells, suggesting that the sumoylation plays a role in restraining the DNA damage checkpoint response caused by transcription-blocking lesions. Our results demonstrate a novel covalent modification of Rpb1 in response to UV induced DNA damage or transcriptional impairment, and unravel an important link between the modification and the DNA damage checkpoint response.
Collapse
Affiliation(s)
- Xuefeng Chen
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Baojin Ding
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Danielle LeJeune
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Christine Ruggiero
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Shisheng Li
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
| |
Collapse
|
38
|
Cook CE, Hochstrasser M, Kerscher O. The SUMO-targeted ubiquitin ligase subunit Slx5 resides in nuclear foci and at sites of DNA breaks. Cell Cycle 2009; 8:1080-9. [PMID: 19270524 PMCID: PMC2700622 DOI: 10.4161/cc.8.7.8123] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Slx5/Slx8 protein complex, a heterodimeric SUMO-targeted ubiquitin ligase, plays an important role in genomic integrity. Slx5/Slx8 is believed to interact with sumoylated proteins that reside in the nuclei of budding yeast cells. In this complex, Slx5, owing to at least two SUMO interacting motifs (SIMs), has been proposed to be the targeting subunit of the Slx8 ubiquitin ligase. However, little is known about the exact subnuclear localization and targets of Slx5/Slx8. In this study we show that Slx5, but not Slx8, forms prominent nuclear foci. The formation of these foci depends on SUMO and a SIM in Slx5. Therefore, we investigated the subnuclear localization and potential chromatin association of Slx5. Using co-localization studies in live cells and fixed chromatin, we were able to localize Slx5 to DNA damage induced foci of Rad52 and Rad9, two proteins involved in the cellular response to DNA damage. Subsequent chromatin immunoprecipitation (ChIP) studies revealed that Slx5 is associated with HO endonuclease induced chromosome breaks. Surprisingly, real-time PCR analysis of Slx5 ChIPs revealed that the level of Slx5 at HO breaks in an slx8 deletion background is reduced about 4-fold. These results indicate that the DNA-damage targeting of Slx5/Slx8 depends on formation of the heterodimer and that this occurs at a subset of nuclear foci also containing DNA damage repair and checkpoint factors.
Collapse
Affiliation(s)
- Caitlin E. Cook
- The College of William & Mary, Biology Dept., Williamsburg, VA 23185
| | - Mark Hochstrasser
- Yale University, Dept. of Molecular Biophysics & Biochemistry, New Haven, CT 06520
| | - Oliver Kerscher
- The College of William & Mary, Biology Dept., Williamsburg, VA 23185
| |
Collapse
|
39
|
Abstract
Post-translational modification of the cell's proteome by ubiquitin and ubiquitin-like proteins provides dynamic functional regulation. Ubiquitin and SUMO are well-studied post-translational modifiers that typically impart distinct effects on their targets. The recent discovery that modification by SUMO can target proteins for ubiquitination and proteasomal degradation sets a new paradigm in the field, and offers insights into the roles of SUMO and ubiquitin in genome stability.
Collapse
|
40
|
Sollier J, Driscoll R, Castellucci F, Foiani M, Jackson SP, Branzei D. The Saccharomyces cerevisiae Esc2 and Smc5-6 proteins promote sister chromatid junction-mediated intra-S repair. Mol Biol Cell 2009; 20:1671-82. [PMID: 19158389 DOI: 10.1091/mbc.e08-08-0875] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recombination is important for DNA repair, but it can also contribute to genome rearrangements. RecQ helicases, including yeast Sgs1 and human BLM, safeguard genome integrity through their functions in DNA recombination. Sgs1 prevents the accumulation of Rad51-dependent sister chromatid junctions at damaged replication forks, and its functionality seems to be regulated by Ubc9- and Mms21-dependent sumoylation. We show that mutations in Smc5-6 and Esc2 also lead to an accumulation of recombinogenic structures at damaged replication forks. Because Smc5-6 is sumoylated in an Mms21-dependent manner, this finding suggests that Smc5-6 may be a crucial target of Mms21 implicated in this process. Our data reveal that Smc5-6 and Esc2 are required to tolerate DNA damage and that their functionality is critical in genotoxic conditions in the absence of Sgs1. As reported previously for Sgs1 and Smc5-6, we find that Esc2 physically interacts with Ubc9 and SUMO. This interaction is correlated with the ability of Esc2 to promote DNA damage tolerance. Collectively, these data suggest that Esc2 and Smc5-6 act in concert with Sgs1 to prevent the accumulation of recombinogenic structures at damaged replication forks, likely by integrating sumoylation activities to regulate the repair pathways in response to damaged DNA.
Collapse
Affiliation(s)
- Julie Sollier
- IFOM, The FIRC Institute for Molecular Oncology Foundation, IFOM-IEO Campus, 20139 Milan, Italy
| | | | | | | | | | | |
Collapse
|
41
|
Quality control of a transcriptional regulator by SUMO-targeted degradation. Mol Cell Biol 2009; 29:1694-706. [PMID: 19139279 DOI: 10.1128/mcb.01470-08] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Slx5 and Slx8 are heterodimeric RING domain-containing proteins that possess SUMO-targeted ubiquitin ligase (STUbL) activity in vitro. Slx5-Slx8 and its orthologs are proposed to target SUMO conjugates for ubiquitin-mediated proteolysis, but the only in vivo substrate identified to date is mammalian PML, and the physiological importance of SUMO-targeted ubiquitylation remains largely unknown. We previously identified mutations in SLX5 and SLX8 by selecting for suppressors of a temperature-sensitive allele of MOT1, which encodes a regulator of TATA-binding protein. Here, we demonstrate that Mot1 is SUMOylated in vivo and that disrupting the Slx5-Slx8 pathway by mutation of the target lysines in Mot1, by deletion of SLX5 or the ubiquitin E2 UBC4, or by inhibition of the proteosome suppresses mot1-301 mutant phenotypes and increases the stability of the Mot1-301 protein. The Mot1-301 mutant protein is targeted for proteolysis by SUMOylation to a much greater extent than wild-type Mot1, suggesting a quality control mechanism. In support of this idea, growth of Saccharomyces cerevisiae in the presence of the arginine analog canavanine results in increased SUMOylation and Slx5-Slx8-mediated degradation of wild-type Mot1. These results therefore demonstrate that Mot1 is an in vivo STUbL target in yeast and suggest a role for SUMO-targeted degradation in protein quality control.
Collapse
|
42
|
Nagai S, Dubrana K, Tsai-Pflugfelder M, Davidson MB, Roberts TM, Brown GW, Varela E, Hediger F, Gasser SM, Krogan NJ. Functional targeting of DNA damage to a nuclear pore-associated SUMO-dependent ubiquitin ligase. Science 2008; 322:597-602. [PMID: 18948542 DOI: 10.1126/science.1162790] [Citation(s) in RCA: 349] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent findings suggest important roles for nuclear organization in gene expression. In contrast, little is known about how nuclear organization contributes to genome stability. Epistasis analysis (E-MAP) using DNA repair factors in yeast indicated a functional relationship between a nuclear pore subcomplex and Slx5/Slx8, a small ubiquitin-like modifier (SUMO)-dependent ubiquitin ligase, which we show physically interact. Real-time imaging and chromatin immunoprecipitation confirmed stable recruitment of damaged DNA to nuclear pores. Relocation required the Nup84 complex and Mec1/Tel1 kinases. Spontaneous gene conversion can be enhanced in a Slx8- and Nup84-dependent manner by tethering donor sites at the nuclear periphery. This suggests that strand breaks are shunted to nuclear pores for a repair pathway controlled by a conserved SUMO-dependent E3 ligase.
Collapse
Affiliation(s)
- Shigeki Nagai
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
van Werven FJ, van Bakel H, van Teeffelen HAAM, Altelaar AFM, Koerkamp MG, Heck AJR, Holstege FCP, Timmers HTM. Cooperative action of NC2 and Mot1p to regulate TATA-binding protein function across the genome. Genes Dev 2008; 22:2359-69. [PMID: 18703679 DOI: 10.1101/gad.1682308] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Promoter recognition by TATA-binding protein (TBP) is an essential step in the initiation of RNA polymerase II (pol II) mediated transcription. Genetic and biochemical studies in yeast have shown that Mot1p and NC2 play important roles in inhibiting TBP activity. To understand how TBP activity is regulated in a genome-wide manner, we profiled the binding of TBP, NC2, Mot1p, TFIID, SAGA, and pol II across the yeast genome using chromatin immunoprecipitation (ChIP)-chip for cells in exponential growth and during reprogramming of transcription. We find that TBP, NC2, and Mot1p colocalize at transcriptionally active pol II core promoters. Relative binding of NC2alpha and Mot1p is higher at TATA promoters, whereas NC2beta has a preference for TATA-less promoters. In line with the ChIP-chip data, we isolated a stable TBP-NC2-Mot1p-DNA complex from chromatin extracts. ATP hydrolysis releases NC2 and DNA from the Mot1p-TBP complex. In vivo experiments indicate that promoter dissociation of TBP and NC2 is highly dynamic, which is dependent on Mot1p function. Based on these results, we propose that NC2 and Mot1p cooperate to dynamically restrict TBP activity on transcribed promoters.
Collapse
Affiliation(s)
- Folkert J van Werven
- Department of Physiological Chemistry, University Medical Center Utrecht, 3584 CG Utrecht, The Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Schimmel J, Larsen KM, Matic I, van Hagen M, Cox J, Mann M, Andersen JS, Vertegaal ACO. The ubiquitin-proteasome system is a key component of the SUMO-2/3 cycle. Mol Cell Proteomics 2008; 7:2107-22. [PMID: 18565875 DOI: 10.1074/mcp.m800025-mcp200] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Many proteins are regulated by a variety of post-translational modifications, and orchestration of these modifications is frequently required for full control of activity. Currently little is known about the combinatorial activity of different post-translational modifications. Here we show that extensive cross-talk exists between sumoylation and ubiquitination. We found that a subset of SUMO-2-conjugated proteins is subsequently ubiquitinated and degraded by the proteasome. In a screen for preferential SUMO-1 or SUMO-2 target proteins, we found that ubiquitin accumulated in purified SUMO-2 conjugates but not in SUMO-1 conjugates. Upon inhibition of the proteasome, the amount of ubiquitin in purified SUMO-2 conjugates increased. In addition, we found that endogenous SUMO-2/3 conjugates, but not endogenous SUMO-1 conjugates, accumulated in response to proteasome inhibitors. Quantitative proteomics experiments enabled the identification of 73 SUMO-2-conjugated proteins that accumulated in cells treated with proteasome inhibitors. Cross-talk between SUMO-2/3 and the ubiquitin-proteasome system controls many target proteins that regulate all aspects of nucleic acid metabolism. Surprisingly the relative abundance of 40 SUMO-2-conjugated proteins was reduced by proteasome inhibitors possibly because of a lack of recycled SUMO-2. We conclude that SUMO-2/3 conjugation and the ubiquitin-proteasome system are tightly integrated and act in a cooperative manner.
Collapse
Affiliation(s)
- Joost Schimmel
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Mullen JR, Brill SJ. Activation of the Slx5-Slx8 ubiquitin ligase by poly-small ubiquitin-like modifier conjugates. J Biol Chem 2008; 283:19912-21. [PMID: 18499666 DOI: 10.1074/jbc.m802690200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Protein sumoylation is a regulated process that is important for the health of human and yeast cells. In budding yeast, a subset of sumoylated proteins is targeted for ubiquitination by a conserved heterodimeric ubiquitin (Ub) ligase, Slx5-Slx8, which is needed to suppress the accumulation of high molecular weight small ubiquitin-like modifier (SUMO) conjugates. Structure-function analysis indicates that the Slx5-Slx8 complex contains multiple SUMO-binding domains that are collectively required for in vivo function. To determine the specificity of Slx5-Slx8, we assayed its Ub ligase activity using sumoylated Siz2 as an in vitro substrate. In contrast to unsumoylated or multisumoylated Siz2, substrates containing poly-SUMO conjugates were efficiently ubiquitinated by Slx5-Slx8. Although Siz2 itself was ubiquitinated, the bulk of the Ub was conjugated to SUMO residues. Slx5-Slx8 primarily mono-ubiquitinated the N-terminal SUMO moiety of the chain. These data indicate that the Slx5-Slx8 Ub ligase is stimulated by poly-SUMO conjugates and that it can ubiquitinate a poly-SUMO chain.
Collapse
Affiliation(s)
- Janet R Mullen
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08854, USA
| | | |
Collapse
|
46
|
Tatham MH, Geoffroy MC, Shen L, Plechanovova A, Hattersley N, Jaffray EG, Palvimo JJ, Hay RT. RNF4 is a poly-SUMO-specific E3 ubiquitin ligase required for arsenic-induced PML degradation. Nat Cell Biol 2008; 10:538-46. [PMID: 18408734 DOI: 10.1038/ncb1716] [Citation(s) in RCA: 657] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 03/19/2008] [Indexed: 11/09/2022]
Abstract
In acute promyelocytic leukaemia (APL), the promyelocytic leukaemia (PML) protein is fused to the retinoic acid receptor alpha (RAR). This disease can be treated effectively with arsenic, which induces PML modification by small ubiquitin-like modifiers (SUMO) and proteasomal degradation. Here we demonstrate that the RING-domain-containing ubiquitin E3 ligase, RNF4 (also known as SNURF), targets poly-SUMO-modified proteins for degradation mediated by ubiquitin. RNF4 depletion or proteasome inhibition led to accumulation of mixed, polyubiquitinated, poly-SUMO chains. PML protein accumulated in RNF4-depleted cells and was ubiquitinated by RNF4 in a SUMO-dependent fashion in vitro. In the absence of RNF4, arsenic failed to induce degradation of PML and SUMO-modified PML accumulated in the nucleus. These results demonstrate that poly-SUMO chains can act as discrete signals from mono-SUMOylation, in this case targeting a poly-SUMOylated substrate for ubiquitin-mediated proteolysis.
Collapse
Affiliation(s)
- Michael H Tatham
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | | | | | | | | | | | | | | |
Collapse
|
47
|
A SIM-ultaneous role for SUMO and ubiquitin. Trends Biochem Sci 2008; 33:201-8. [PMID: 18403209 DOI: 10.1016/j.tibs.2008.02.001] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 02/08/2008] [Accepted: 02/12/2008] [Indexed: 11/22/2022]
Abstract
Ubiquitin and ubiquitin-like proteins (Ubls) share a beta-GRASP fold and have key roles in cellular growth and suppression of genome instability. Despite their common fold, SUMO and ubiquitin are classically portrayed as distinct, and they can have antagonistic roles. Recently, a new family of proteins, the small ubiquitin-related modifier (SUMO)-targeted ubiquitin ligases (STUbLs), which directly connect sumoylation and ubiquitylation, has been discovered. Uniquely, STUbLs use SUMO-interaction motifs (SIMs) to recognize their sumoylated targets. STUbLs are global regulators of protein sumoylation levels, and cells lacking STUbLs display genomic instability and hypersensitivity to genotoxic stress. The human STUbL, RNF4, is implicated in several diseases including cancer, highlighting the importance of characterizing the cellular functions of STUbLs.
Collapse
|
48
|
Hunter T, Sun H. Crosstalk between the SUMO and ubiquitin pathways. ERNST SCHERING FOUNDATION SYMPOSIUM PROCEEDINGS 2008:1-16. [PMID: 19202597 DOI: 10.1007/2789_2008_098] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Several ways in which the SUMO and ubiquitin pathways can intersect and communicate have recently been discovered. This review discusses the principles of crosstalk between SUMOylation and ubiquitination, focusing on the RNF4 family of RING finger E3 ubiquitin ligases, which specifically recognize SUMOylated proteins via their SUMO moiety for ubiquitination.
Collapse
Affiliation(s)
- T Hunter
- Molecular and Cell Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 920137-1099, USA.
| | | |
Collapse
|
49
|
Slx5 promotes transcriptional silencing and is required for robust growth in the absence of Sir2. Mol Cell Biol 2007; 28:1361-72. [PMID: 18086879 DOI: 10.1128/mcb.01291-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The broadly conserved Sir2 NAD(+)-dependent deacetylase is required for chromatin silencing. Here we report the discovery of physical and functional links between Sir2 and Slx5 (Hex3), a RING domain protein and subunit of the Slx5/8 complex, [corrected] which is a ubiquitin E3 ligase that targets sumoylated proteins. Slx5 interacted with Sir2 by two-hybrid and glutathione S-transferase-binding assays and was found to promote silencing of genes at telomeric or ribosomal DNA (rDNA) loci. However, deletion of SLX5 had no detectable effect on the distribution of silent chromatin components and only slightly altered the deacetylation of histone H4 lysine 16 at the telomere. In vivo assays indicated that Sir2-dependent silencing was functionally intact in the absence of Slx5. Although no previous reports suggest that Sir2 contributes to the fitness of yeast populations, we found that Sir2 was required for maximal growth in slx5Delta mutant cells. A similar requirement was observed for mutants of the SUMO isopeptidase Ulp2/Smt4. The contribution of Sir2 to optimal growth was not due to known Sir2 roles in mating-type determination or rDNA maintenance but was connected to a role of sumoylation in transcriptional silencing. These results indicate that Sir2 and Slx5 jointly contribute to transcriptional silencing and robust cellular growth.
Collapse
|
50
|
Mousson F, Kolkman A, Pijnappel WWMP, Timmers HTM, Heck AJR. Quantitative proteomics reveals regulation of dynamic components within TATA-binding protein (TBP) transcription complexes. Mol Cell Proteomics 2007; 7:845-52. [PMID: 18087068 DOI: 10.1074/mcp.m700306-mcp200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Affinity purification in combination with isotope labeling of proteins has proven to be a powerful method to discriminate specific from nonspecific interactors. However, in the standard SILAC (stable isotope labeling by amino acids in cell culture) approach dynamic components may easily be assigned as nonspecific. We compared two affinity purification protocols, which in combination revealed information on the dynamics of protein complexes. We focused on the central component in eukaryotic transcription, the human TATA-binding protein, which is involved in different complexes. All known TATA-binding protein-associated factors (TAFs) were detected as specific interactors. Interestingly one of them, BTAF1, exchanged significantly in cell extracts during the affinity purification. The other TAFs did not display this behavior. Cell cycle synchronization showed that BTAF1 exchange was regulated during mitosis. The combination of the two affinity purification protocols allows a quantitative approach to identify transient components in any protein complex.
Collapse
Affiliation(s)
- Florence Mousson
- Department of Physiological Chemistry, University Medical Centre Utrecht, Universiteitsweg 100, 3584CG Utrecht, The Netherlands
| | | | | | | | | |
Collapse
|