1
|
Spataro V, Buetti-Dinh A. POH1/Rpn11/PSMD14: a journey from basic research in fission yeast to a prognostic marker and a druggable target in cancer cells. Br J Cancer 2022; 127:788-799. [PMID: 35501388 PMCID: PMC9428165 DOI: 10.1038/s41416-022-01829-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/06/2022] [Accepted: 04/11/2022] [Indexed: 12/11/2022] Open
Abstract
POH1/Rpn11/PSMD14 is a highly conserved protein in eukaryotes from unicellular organisms to human and has a crucial role in cellular homoeostasis. It is a subunit of the regulatory particle of the proteasome, where it acts as an intrinsic deubiquitinase removing polyubiquitin chains from substrate proteins. This function is not only coupled to the translocation of substrates into the core of the proteasome and their subsequent degradation but also, in some instances, to the stabilisation of ubiquitinated proteins through their deubiquitination. POH1 was initially discovered as a functional homologue of the fission yeast gene pad1+, which confers drug resistance when overexpressed. In translational studies, expression of POH1 has been found to be increased in several tumour types relative to normal adjacent tissue and to correlate with tumour progression, higher tumour grade, decreased sensitivity to cytotoxic drugs and poor prognosis. Proteasome inhibitors targeting the core particle of the proteasome are highly active in the treatment of myeloma, and recently developed POH1 inhibitors, such as capzimin and thiolutin, have shown promising anticancer activity in cell lines of solid tumours and leukaemia. Here we give an overview of POH1 function in the cell, of its potential role in oncogenesis and of recent progress in developing POH1-targeting drugs.
Collapse
Affiliation(s)
- Vito Spataro
- Service of Medical Oncology, Oncology Institute of Southern Switzerland (IOSI), Ospedale San Giovanni, Via Gallino, 6500, Bellinzona, Switzerland.
| | - Antoine Buetti-Dinh
- Institute of Microbiology, Department of Environmental Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), via Mirasole 22a, 6500, Bellinzona, Switzerland.,Swiss Institute of Bioinformatics, Quartier Sorge, Batiment Genopode, 1015, Lausanne, Switzerland
| |
Collapse
|
2
|
Marte L, Boronat S, García-Santamarina S, Ayté J, Kitamura K, Hidalgo E. Identification of ubiquitin-proteasome system components affecting the degradation of the transcription factor Pap1. Redox Biol 2019; 28:101305. [PMID: 31514053 PMCID: PMC6742857 DOI: 10.1016/j.redox.2019.101305] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/13/2019] [Accepted: 08/20/2019] [Indexed: 01/06/2023] Open
Abstract
Signaling cascades respond to specific inputs, but also require active interventions to be maintained in their basal/inactive levels in the absence of the activating signal(s). In a screen to search for protein quality control components required for wild-type tolerance to oxidative stress in fission yeast, we have isolated eight gene deletions conferring resistance not only to H2O2 but also to caffeine. We show that dual resistance acquisition is totally or partially dependent on the transcription factor Pap1. Some gene products, such as the ribosomal-ubiquitin fusion protein Ubi1, the E2 conjugating enzyme Ubc2 or the E3 ligase Ubr1, participate in basal ubiquitin labeling of Pap1, and others, such as Rpt4, are non-essential constituents of the proteasome. We demonstrate here that basal nucleo-cytoplasmic shuttling of Pap1, occurring even in the absence of stress, is sufficient for the interaction of the transcription factor with nuclear Ubr1, and we identify a 30 amino acids peptide in Pap1 as the degron for this important E3 ligase. The isolated gene deletions increase only moderately the concentration of the transcription factor, but it is sufficient to enhance basal tolerance to stress, probably by disturbing the inactive stage of this signaling cascade.
Collapse
Affiliation(s)
- Luis Marte
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/ Doctor Aiguader 88, 08003, Barcelona, Spain
| | - Susanna Boronat
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/ Doctor Aiguader 88, 08003, Barcelona, Spain
| | - Sarela García-Santamarina
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/ Doctor Aiguader 88, 08003, Barcelona, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/ Doctor Aiguader 88, 08003, Barcelona, Spain
| | - Kenji Kitamura
- Center for Gene Science, Hiroshima University, 1-4-2 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/ Doctor Aiguader 88, 08003, Barcelona, Spain.
| |
Collapse
|
3
|
Beckley JR, Chen JS, Yang Y, Peng J, Gould KL. A Degenerate Cohort of Yeast Membrane Trafficking DUBs Mediates Cell Polarity and Survival. Mol Cell Proteomics 2015; 14:3132-41. [PMID: 26412298 DOI: 10.1074/mcp.m115.050039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Indexed: 12/26/2022] Open
Abstract
Deubiquitinating enzymes (DUBs), cysteine or metallo- proteases that cleave ubiquitin chains or protein conjugates, are present in nearly every cellular compartment, with overlapping protein domain structure, localization, and functions. We discovered a cohort of DUBs that are involved in membrane trafficking (ubp4, ubp5, ubp9, ubp15, and sst2) and found that loss of all five of these DUBs but not loss of any combination of four, significantly impacted cell viability in the fission yeast Schizosaccharomyces pombe (1). Here, we delineate the collective and individual functions and activities of these five conserved DUBs using comparative proteomics, biochemistry, and microscopy. We find these five DUBs are degenerate rather than redundant at the levels of cell morphology, substrate selectivity, ubiquitin chain specificity, and cell viability under stress. These studies reveal the complexity of interplay among these enzymes, providing a foundation for understanding DUB biology and providing another example of how cells utilize degeneracy to improve survival.
Collapse
Affiliation(s)
- Janel R Beckley
- From the Cell & Developmental Biology, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, TN 37232
| | - Jun-Song Chen
- From the Cell & Developmental Biology, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, TN 37232
| | - Yanling Yang
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105
| | - Junmin Peng
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, TN 38105
| | - Kathleen L Gould
- From the Cell & Developmental Biology, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, TN 37232
| |
Collapse
|
4
|
Histone H2B ubiquitination promotes the function of the anaphase-promoting complex/cyclosome in Schizosaccharomyces pombe. G3-GENES GENOMES GENETICS 2014; 4:1529-38. [PMID: 24948786 PMCID: PMC4132182 DOI: 10.1534/g3.114.012625] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ubiquitination and deubiquitination of proteins are reciprocal events involved in many cellular processes, including the cell cycle. During mitosis, the metaphase to anaphase transition is regulated by the ubiquitin ligase activity of the anaphase-promoting complex/cyclosome (APC/C). Although the E3 ubiquitin ligase function of the APC/C has been well characterized, it is not clear whether deubiquitinating enzymes (DUBs) play a role in reversing APC/C substrate ubiquitination. Here we performed a genetic screen to determine what DUB, if any, antagonizes the function of the APC/C in the fission yeast Schizosaccharomyces pombe. We found that deletion of ubp8, encoding the Spt-Ada-Gcn5-Acetyl transferase (SAGA) complex associated DUB, suppressed temperature-sensitive phenotypes of APC/C mutants cut9-665, lid1-6, cut4-533, and slp1-362. Our analysis revealed that Ubp8 antagonizes APC/C function in a mechanism independent of the spindle assembly checkpoint and proteasome activity. Notably, suppression of APC/C mutants was linked to loss of Ubp8 catalytic activity and required histone H2B ubiquitination. On the basis of these data, we conclude that Ubp8 antagonizes APC/C function indirectly by modulating H2B ubiquitination status.
Collapse
|
5
|
Kang SS, Shin SH. Phosphorylation of human chromosome maintenance 1 mediates association with 14-3-3 proteins. Anim Cells Syst (Seoul) 2013. [DOI: 10.1080/19768354.2013.801366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
|
6
|
Penney M, Samejima I, Wilkinson CR, McInerny CJ, Mathiassen SG, Wallace M, Toda T, Hartmann-Petersen R, Gordon C. Fission yeast 26S proteasome mutants are multi-drug resistant due to stabilization of the Pap1 transcription factor. PLoS One 2012; 7:e50796. [PMID: 23209828 PMCID: PMC3507774 DOI: 10.1371/journal.pone.0050796] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/25/2012] [Indexed: 01/12/2023] Open
Abstract
Here we report the result of a genetic screen for mutants resistant to the microtubule poison methyl benzimidazol-2-yl carbamate (MBC) that were also temperature sensitive for growth. In total the isolated mutants were distributed in ten complementation groups. Cloning experiments revealed that most of the mutants were in essential genes encoding various 26S proteasome subunits. We found that the proteasome mutants are multi-drug resistant due to stabilization of the stress-activated transcription factor Pap1. We show that the ubiquitylation and ultimately the degradation of Pap1 depend on the Rhp6/Ubc2 E2 ubiquitin conjugating enzyme and the Ubr1 E3 ubiquitin-protein ligase. Accordingly, mutants lacking Rhp6 or Ubr1 display drug-resistant phenotypes.
Collapse
Affiliation(s)
- Mary Penney
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Itaru Samejima
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Caroline R. Wilkinson
- Cell Regulation Group, Paterson Institute for Cancer Research, University of Manchester, Manchester, United Kingdom
| | - Christopher J. McInerny
- Division of Molecular and Cellular Biology, School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Søs G. Mathiassen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Mairi Wallace
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
| | | | - Colin Gordon
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| |
Collapse
|
7
|
Calvo IA, García P, Ayté J, Hidalgo E. The transcription factors Pap1 and Prr1 collaborate to activate antioxidant, but not drug tolerance, genes in response to H2O2. Nucleic Acids Res 2012; 40:4816-24. [PMID: 22344694 PMCID: PMC3367182 DOI: 10.1093/nar/gks141] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In response to hydrogen peroxide (H2O2), the transcription factor Pap1 from Schizosaccharomyces pombe regulates transcription of genes required for adaptation to oxidative stress and for tolerance to toxic drugs. H2O2 induces oxidation of Pap1, its nuclear accumulation and expression of more than fifty Pap1-dependent genes. Oxidation and nuclear accumulation of Pap1 can also be accomplished by genetic inhibition of thioredoxin reductase. Furthermore, genetic alteration of the nuclear export pathway, or mutations in Pap1 nuclear export signal trigger nuclear accumulation of reduced Pap1. We show here that a subset of Pap1-dependent genes, such as those coding for the efflux pump Caf5, the ubiquitin-like protein Obr1 or the dehydrogenase SPCC663.08c, only require nuclear Pap1 for activation, whereas another subset of genes, those coding for the antioxidants catalase, sulfiredoxin or thioredoxin reductase, do need oxidized Pap1 to form a heterodimer with the constitutively nuclear transcription factor Prr1. The ability of Pap1 to bind and activate drug tolerance promoters is independent on Prr1, whereas its affinity for the antioxidant promoters is significantly enhanced upon association with Prr1. This finding suggests that the activation of both antioxidant and drug resistance genes in response to oxidative stress share a common inducer, H2O2, but alternative effectors.
Collapse
Affiliation(s)
- Isabel A Calvo
- Oxidative Stress and Cell Cycle Group, Department de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/Dr. Aiguader 88, E-08003 Barcelona, Spain
| | | | | | | |
Collapse
|
8
|
Kitamura K, Taki M, Tanaka N, Yamashita I. Fission yeast Ubr1 ubiquitin ligase influences the oxidative stress response via degradation of active Pap1 bZIP transcription factor in the nucleus. Mol Microbiol 2011; 80:739-55. [PMID: 21410566 DOI: 10.1111/j.1365-2958.2011.07605.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cells adapt to oxidative stress by transcriptional activation of genes encoding antioxidants and proteins of other protective roles. A bZIP transcription factor, Pap1, plays a critical role in this process and overexpression of Pap1 confers resistance to various oxidants and drugs in fission yeast. Pap1 temporarily enters the nucleus upon oxidative stress but returns to the cytoplasm once cells adapt to the stress, suggesting that cellular localization regulates Pap1 function. We report here an additional regulatory mechanism that Ubr1 ubiquitin ligase-dependent degradation lowered the Pap1 protein levels. ubr1 cells were causally resistant to hydrogen peroxide because of the increment of Pap1 levels. Pap1 was preferentially degraded in the nucleus where Ubr1 was consistently enriched. Proteolysis was critical to downregulate Pap1 especially when its activation persisted, as constitutively nuclear Pap1 severely inhibited growth in ubr1 mutants. Inactive mutations in the bZIP DNA binding domain stabilized Pap1 but rescued the lethality caused by constitutively active Pap1 in ubr1 mutants. These findings indicate that either nuclear export or Ubr1-mediated proteolysis must be operative to prevent uncontrolled Pap1 function. Coincidental dysfunction in both inhibitory pathways causes lethality because of prolonged activation of Pap1. Ubr1 is a critical regulator for the homeostasis of oxidative stress response.
Collapse
Affiliation(s)
- Kenji Kitamura
- Center for Gene Science, Hiroshima University, Kagamiyama 1-4-2, Higashi-Hiroshima 739-8527, Japan.
| | | | | | | |
Collapse
|
9
|
Kouranti I, McLean JR, Feoktistova A, Liang P, Johnson AE, Roberts-Galbraith RH, Gould KL. A global census of fission yeast deubiquitinating enzyme localization and interaction networks reveals distinct compartmentalization profiles and overlapping functions in endocytosis and polarity. PLoS Biol 2010; 8. [PMID: 20838651 PMCID: PMC2935449 DOI: 10.1371/journal.pbio.1000471] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 07/20/2010] [Indexed: 11/20/2022] Open
Abstract
Proteomic, localization, and enzymatic activity screens in fission yeast reveal how deubiquitinating enzyme localization and function are tuned. Ubiquitination and deubiquitination are reciprocal processes that tune protein stability, function, and/or localization. The removal of ubiquitin and remodeling of ubiquitin chains is catalyzed by deubiquitinating enzymes (DUBs), which are cysteine proteases or metalloproteases. Although ubiquitination has been extensively studied for decades, the complexity of cellular roles for deubiquitinating enzymes has only recently been explored, and there are still several gaps in our understanding of when, where, and how these enzymes function to modulate the fate of polypeptides. To address these questions we performed a systematic analysis of the 20 Schizosaccharomyces pombe DUBs using confocal microscopy, proteomics, and enzymatic activity assays. Our results reveal that S. pombe DUBs are present in almost all cell compartments, and the majority are part of stable protein complexes essential for their function. Interestingly, DUB partners identified by our study include the homolog of a putative tumor suppressor gene not previously linked to the ubiquitin pathway, and two conserved tryptophan-aspartate (WD) repeat proteins that regulate Ubp9, a DUB that we show participates in endocytosis, actin dynamics, and cell polarity. In order to understand how DUB activity affects these processes we constructed multiple DUB mutants and find that a quintuple deletion of ubp4 ubp5 ubp9 ubp15 sst2/amsh displays severe growth, polarity, and endocytosis defects. This mutant allowed the identification of two common substrates for five cytoplasmic DUBs. Through these studies, a common regulatory theme emerged in which DUB localization and/or activity is modulated by interacting partners. Despite apparently distinct cytoplasmic localization patterns, several DUBs cooperate in regulating endocytosis and cell polarity. These studies provide a framework for dissecting DUB signaling pathways in S. pombe and may shed light on DUB functions in metazoans. The post-translational modification of proteins by conjugation of monomers or chains of ubiquitin is a regulatory mechanism for tuning protein stability, localization and function. Given these vital functions, ubiquitination has to be highly regulated so that protein degradation and cell signaling are controlled in space and time. Although the ubiquitin-conjugation machinery has been thoroughly studied, there are still several gaps in our understanding of when, where and how ubiquitin is removed by deubiquitinating enzymes (DUBs). To address these questions we performed a systematic analysis of the 20 DUBs in the fission yeast Schizosaccharomyces pombe using confocal microscopy, proteomics and enzymatic activity assays. We first showed that S. pombe DUBs are present in almost all cell compartments and that the majority are part of stable protein complexes essential for their function. Then, we constructed strains mutant for a number of the DUBs involved in the newly identified protein complexes and showed that five cytoplasmic DUBs have redundant roles in controlling endocytosis and cell polarity. We postulate that regulatory networks identified in our study might be conserved and hence shed light on DUB function in metazoans.
Collapse
Affiliation(s)
- Ilektra Kouranti
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Janel R. McLean
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Anna Feoktistova
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Ping Liang
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Alyssa E. Johnson
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Rachel H. Roberts-Galbraith
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
| |
Collapse
|
10
|
Cunha AF, Sousa MV, Silva SP, JesuÍno RSA, Soares CMA, Felipe MSS. Identification, N-terminal region sequencing and similarity analysis of differentially expressed proteins in Paracoccidioides brasiliensis. Med Mycol 2008. [DOI: 10.1111/j.1365-280x.1999.00211.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
11
|
Smith L, Lind MJ, Drew PJ, Cawkwell L. The putative roles of the ubiquitin/proteasome pathway in resistance to anticancer therapy. Eur J Cancer 2007; 43:2330-8. [PMID: 17888650 DOI: 10.1016/j.ejca.2007.07.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 07/09/2007] [Accepted: 07/18/2007] [Indexed: 12/11/2022]
Abstract
The ubiquitin/proteasome (UP) pathway plays a significant role in many important biological functions and alterations in this pathway have been shown to contribute to the pathology of many human diseases, including cancer. Proteasome inhibition has been well established as a rational strategy for the treatment of multiple myeloma and is currently under investigation for the treatment of other haematological malignancies and solid tumours. Recent evidence suggests that proteasome inhibition may also sensitise tumour cells to the actions of both conventional chemotherapy and radiotherapy, suggesting that this pathway may modify clinical response to anticancer therapy. However, conflicting evidence exists as to the roles of the UP pathway in resistance to treatment. This review endeavours to discuss such roles.
Collapse
Affiliation(s)
- Laura Smith
- Cancer Biology Proteomics Group, Postgraduate Medical Institute of the University of Hull, UK
| | | | | | | |
Collapse
|
12
|
Natalello A, Doglia SM, Carey J, Grandori R. Role of flavin mononucleotide in the thermostability and oligomerization of Escherichia coli stress-defense protein WrbA. Biochemistry 2007; 46:543-53. [PMID: 17209564 DOI: 10.1021/bi061769c] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
WrbA is an oligomeric flavodoxin-like protein that binds one molecule of flavin mononucleotide (FMN) per monomer and whose redox activity is implicated in oxidative stress defense. WrbA thermostability and oligomerization in the presence and absence of bound FMN were investigated using complementary biophysical methods. Infrared spectroscopy indicates similar structures for apo and holoWrbA. FMN binding has a dramatic effect on WrbA thermal stability, shifting the Tm by approximately 40 degrees C. Upon denaturation, the protein forms insoluble aggregates that lack native secondary structure and have no bound FMN. Circular dichroism (CD) reveals that the thermal unfolding of apo and holoWrbA proceeds via the formation of an aggregation-prone intermediate that retains substantial secondary structure but has lost the native configuration of the active site. This intermediate persists in solution up to 100 degrees C at micromolar concentrations. A similar partially folded state is populated during chemical denaturation with guanidinium chloride, but accumulation of the intermediate is evident only in the absence of FMN. The results also suggest that WrbA maintains some interaction with FMN in its partially folded state, despite the loss of the induced CD signal of FMN. On the basis of these data, the unfolding process can be depicted as follows: native holoprotein --> holointermediate --> apointermediate --> insoluble aggregate. Mass spectrometry shows that FMN promotes WrbA association into tetramers, which are more thermoresistant than dimers or monomers, suggesting that multimerization underlies the FMN effect on WrbA thermostability. This study illustrates the utility of analyzing conformational transitions and intermolecular interactions using methods that probe the liquid, solid, and gas phases.
Collapse
Affiliation(s)
- Antonino Natalello
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | | | | | | |
Collapse
|
13
|
Patridge EV, Ferry JG. WrbA from Escherichia coli and Archaeoglobus fulgidus is an NAD(P)H:quinone oxidoreductase. J Bacteriol 2006; 188:3498-506. [PMID: 16672604 PMCID: PMC1482846 DOI: 10.1128/jb.188.10.3498-3506.2006] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
WrbA (tryptophan [W] repressor-binding protein) was discovered in Escherichia coli, where it was proposed to play a role in regulation of the tryptophan operon; however, this has been put in question, leaving the function unknown. Here we report a phylogenetic analysis of 30 sequences which indicated that WrbA is the prototype of a distinct family of flavoproteins which exists in a diversity of cell types across all three domains of life and includes documented NAD(P)H:quinone oxidoreductases (NQOs) from the Fungi and Viridiplantae kingdoms. Biochemical characterization of the prototypic WrbA protein from E. coli and WrbA from Archaeoglobus fulgidus, a hyperthermophilic species from the Archaea domain, shows that these enzymes have NQO activity, suggesting that this activity is a defining characteristic of the WrbA family that we designate a new type of NQO (type IV). For E. coli WrbA, the K(m)(NADH) was 14 +/- 0.43 microM and the K(m)(benzoquinone) was 5.8 +/- 0.12 microM. For A. fulgidus WrbA, the K(m)(NADH) was 19 +/- 1.7 microM and the K(m)(benzoquinone) was 37 +/- 3.6 microM. Both enzymes were found to be homodimeric by gel filtration chromatography and homotetrameric by dynamic light scattering and to contain one flavin mononucleotide molecule per monomer. The NQO activity of each enzyme is retained over a broad pH range, and apparent initial velocities indicate that maximal activities are comparable to the optimum growth temperature for the respective organisms. The results are discussed and implicate WrbA in the two-electron reduction of quinones, protecting against oxidative stress.
Collapse
Affiliation(s)
- Eric V Patridge
- Department of Biochemistry and Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, 16802-4500, USA
| | | |
Collapse
|
14
|
Nabhan JF, Ribeiro P. The 19 S proteasomal subunit POH1 contributes to the regulation of c-Jun ubiquitination, stability, and subcellular localization. J Biol Chem 2006; 281:16099-107. [PMID: 16569633 DOI: 10.1074/jbc.m512086200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The AP1 (activator protein 1) transcription factor, c-Jun, is an important regulator of cell proliferation, differentiation, survival, and death. Its activity is regulated both at the level of transcription and post-translationally through phosphorylation, sumoylation, and targeted degradation. The degradation of c-Jun by the ubiquitin proteasome pathway has been well established. Here, we report that POH1, a subunit of the 19 S proteasome lid with a recently described deubiquitinase activity, is a regulator of c-Jun. Ectopic expression of POH1 in HEK293 cells decreased the level of c-Jun ubiquitination, leading to significant accumulation of the protein and a corresponding increase in AP1-mediated gene expression. The stabilization also correlated with a redistribution of c-Jun in the nucleus. These effects were reduced by mutation of a cysteine residue in the Mpr1 pad1 N-terminal plus motif of POH1 (Cys-120) and appeared to be selective for c-Jun, because POH1 had no effect on other proteasomal substrates. Our results identify a novel mechanism of c-Jun regulation in mammalian cells.
Collapse
Affiliation(s)
- Joseph F Nabhan
- Institute of Parasitology, Macdonald Campus, McGill University, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada
| | | |
Collapse
|
15
|
Jenkins CCL, Mata J, Crane RF, Thomas B, Akoulitchev A, Bähler J, Norbury CJ. Activation of AP-1-dependent transcription by a truncated translation initiation factor. EUKARYOTIC CELL 2006; 4:1840-50. [PMID: 16278451 PMCID: PMC1287857 DOI: 10.1128/ec.4.11.1840-1850.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Int6/eIF3e is a highly conserved subunit of eukaryotic translation initiation factor 3 (eIF3) that has also been reported to interact with subunits of the proteasome and the COP9 signalosome. Overexpression of full-length Int6 or a 13-kDa C-terminal fragment, Int6CT, in the fission yeast Schizosaccharomyces pombe causes multidrug resistance that requires the otherwise inessential AP-1 transcription factor Pap1. Here we show for the first time that Int6CT acts to increase the transcriptional activity of Pap1. Microarray hybridization data indicate that Int6CT overexpression resulted in the up-regulation of 67 genes; this expression profile closely matched that of cells overexpressing Pap1. Analysis of the upstream regulatory sequences of these genes showed that the majority contained AP-1 consensus binding sites. Partial defects in ubiquitin-dependent proteolysis have been suggested to confer Pap1-dependent multidrug resistance, but no such defect was seen on Int6CT overexpression. Indeed, none of the previously identified interactions of endogenous Int6 was required for the activation of Pap1 transcription described here. Moreover, Int6CT-induced activation of Pap1-responsive gene expression was independent of the ability of Pap1 to undergo a redox-regulated conformational change which mediates its relocalization to the nucleus and expression of oxidative stress response genes. Int6CT therefore activates Pap1-dependent transcription by a novel mechanism.
Collapse
Affiliation(s)
- Caroline C L Jenkins
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
16
|
Rinaldi T, Pick E, Gambadoro A, Zilli S, Maytal-Kivity V, Frontali L, Glickman M. Participation of the proteasomal lid subunit Rpn11 in mitochondrial morphology and function is mapped to a distinct C-terminal domain. Biochem J 2004; 381:275-85. [PMID: 15018611 PMCID: PMC1133786 DOI: 10.1042/bj20040008] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 03/09/2004] [Accepted: 03/12/2004] [Indexed: 11/17/2022]
Abstract
Substrates destined for degradation by the 26 S proteasome are labelled with polyubiquitin chains. Rpn11/Mpr1, situated in the lid subcomplex, partakes in the processing of these chains or in their removal from substrates bound to the proteasome. Rpn11 also plays a role in maintaining mitochondrial integrity, tubular structure and proper function. The recent finding that Rpn11 participates in proteasome-associated deubiquitination focuses interest on the MPN+ (Mpr1, Pad1, N-terminal)/JAMM (JAB1/MPN/Mov34) metalloprotease site in its N-terminal domain. However, Rpn11 damaged at its C-terminus (the mpr1-1 mutant) causes pleiotropic effects, including proteasome instability and mitochondrial morphology defects, resulting in both proteolysis and respiratory malfunctions. We find that overexpression of WT (wild-type) RPN8, encoding a paralogous subunit that does not contain the catalytic MPN+ motif, corrects proteasome conformations and rescues cell cycle phenotypes, but is unable to correct defects in the mitochondrial tubular system or respiratory malfunctions associated with the mpr1-1 mutation. Transforming mpr1-1 with various RPN8-RPN11 chimaeras or with other rpn11 mutants reveals that a WT C-terminal region of Rpn11 is necessary, and more surprisingly sufficient, to rescue the mpr1-1 mitochondrial phenotype. Interestingly, single-site mutants in the catalytic MPN+ motif at the N-terminus of Rpn11 lead to reduced proteasome-dependent deubiquitination connected with proteolysis defects. Nevertheless, these rpn11 mutants suppress the mitochondrial phenotypes associated with mpr1-1 by intragene complementation. Together, these results point to a unique role for the C-terminal region of Rpn11 in mitochondrial maintenance that may be independent of its role in proteasome-associated deubiquitination.
Collapse
Affiliation(s)
- Teresa Rinaldi
- *Pasteur Institute Cenci Bolognetti Foundation and the Department of Cell and Developmental Biology, University of Rome I, 00185 Rome, Italy
| | - Elah Pick
- †Department of Biology and the Institute for Catalysis Science and Technology, The Technion, 32000 Haifa, Israel
| | - Alessia Gambadoro
- *Pasteur Institute Cenci Bolognetti Foundation and the Department of Cell and Developmental Biology, University of Rome I, 00185 Rome, Italy
| | - Stefania Zilli
- *Pasteur Institute Cenci Bolognetti Foundation and the Department of Cell and Developmental Biology, University of Rome I, 00185 Rome, Italy
| | - Vered Maytal-Kivity
- †Department of Biology and the Institute for Catalysis Science and Technology, The Technion, 32000 Haifa, Israel
| | - Laura Frontali
- *Pasteur Institute Cenci Bolognetti Foundation and the Department of Cell and Developmental Biology, University of Rome I, 00185 Rome, Italy
- To whom correspondence can be addressed (e-mail . or )
| | - Michael H. Glickman
- †Department of Biology and the Institute for Catalysis Science and Technology, The Technion, 32000 Haifa, Israel
- To whom correspondence can be addressed (e-mail . or )
| |
Collapse
|
17
|
Thompson HGR, Harris JW, Brody JP. Post-translationally modified S12, absent in transformed breast epithelial cells, is not associated with the 26S proteasome and is induced by proteasome inhibitor. Int J Cancer 2004; 111:338-47. [PMID: 15221960 DOI: 10.1002/ijc.20261] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The 26S proteasome, consisting of the 20S core and 19S regulatory complexes, regulates intracellular protein concentration through proteolytic degradation of targeted substrates. Composition of the 19S regulatory complex as well as posttranslational modifications of the 19S subunits can effectively regulate the activity of the 26S proteasome. Aberrant activity of the 26S proteasome affects the cell cycle, apoptosis and other cellular processes related to cancer. Recent data show an additional proteasome-independent role of 19S subunits in transcriptional regulation. S12 (Rpn8), the human homologue of mouse Mov-34, is a non-ATPase 19S regulatory subunit of the 26S proteasome. Previous studies have identified phosphorylated S12. In our study, we identify a modified S12 isoform (S12-M) with distinct biochemical properties. The S12-M isoform was found in 6 normal, but not 4 transformed, breast epithelial cell lines. Modification of S12 protein can be induced in vitro by addition of the proteasome inhibitor PSI. Modified and unmodified S12 have similar mass, but different isoelectric points, consistent with phosphorylation. In normal cells, unmodified S12 associates with the 26S proteasome, while modified S12-M does not. Whereas transformed cell line nuclei contain neither S12 isoform, S12-M is predominantly cytosolic in normal cells, with the unmodified S12 present in both the nuclei and cytosol. Together with the role of 19S subunits in transcriptional regulation, homology between S12 and eIF3 and TFIIH subunits, coelution with immunoproteasome subunits, and differential posttranslational modification and nuclear localization, these data suggest a differential nuclear function of modified and unmodified S12 in cancer.
Collapse
Affiliation(s)
- H Garrett R Thompson
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697-2715, USA
| | | | | |
Collapse
|
18
|
Benko Z, Fenyvesvolgyi C, Pesti M, Sipiczki M. The transcription factor Pap1/Caf3 plays a central role in the determination of caffeine resistance in Schizosaccharomyces pombe. Mol Genet Genomics 2004; 271:161-70. [PMID: 14758541 DOI: 10.1007/s00438-003-0967-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2003] [Accepted: 12/02/2003] [Indexed: 01/28/2023]
Abstract
We previously identified four nuclear genes (caf1+-caf4+) in Schizosaccharomyces pombe, mutations in which confer resistance to caffeine and brefeldin A. caf1+, caf2+ and caf4+ were sequenced and found to be identical to the multidrug-resistance/stress-response genes hba1, crm1 and trr1, respectively. Here we show that caf3 is allelic to pap1, which encodes an AP-1-like transcription factor. The allele associated with caffeine resistance, caf3-89, contains a single-nucleotide exchange that results in a Leu-->Ser exchange in the NES (nuclear export signal) domain of the gene product. Due to this alteration, the modified protein can not be exported from the nucleus back into the cytoplasm, and thus accumulates in the nucleus. The activity of pap1/caf3 is shown to be necessary for manifestation of the caffeine resistance caused by mutations in the genes hba1/caf1 and crm1/caf2. We also cloned two genes that confer caffeine resistance when carried on a multicopy plasmid. One of them turned out to be a truncated allele of pad1/bfr2/sks1, which codes for a subunit of the 26 S proteosome. The putative product of the other gene, designated caf5, has a structure highly similar to that of MFS permeases. It contains two groups of six transmembrane spanning domains each, with the conserved motifs WRW, PET and GAIGGPVLGP in the fifth and sixth domains. These results are all consistent with our earlier hypothesis, which suggested that the caf genes are functionally interlinked in a complex detoxification mechanism. caf5 and pad1 may also encode parts of this mechanism.
Collapse
Affiliation(s)
- Z Benko
- Department of Genetics, University of Debrecen, PO Box 56, H-4010 Debrecen, Hungary
| | | | | | | |
Collapse
|
19
|
Kitajima K, Matsumoto K, Tahara M, Takahashi H, Nakamura T, Nakamura T. A newly identified AMSH-family protein is specifically expressed in haploid stages of testicular germ cells. Biochem Biophys Res Commun 2003; 309:135-42. [PMID: 12943674 DOI: 10.1016/s0006-291x(03)01550-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Associated Molecule with SH3 domain of STAM (AMSH) plays a critical role in the cytokine-mediated intracellular signal transduction downstream of the Jak2/Jak3-STAM complex. We newly identified a family molecule of AMSH, AMSH-FP (AMSH-Family Protein) in the mouse brain. AMSH-FP encodes the intracellular protein and has a highly conserved JAB1 Subdomain Homologous (JSH) region, suggesting that AMSH-FP may act as adaptor of gene transcription and/or regulation system. AMSH-FP has two splicing forms, one is expressed in various tissues, whereas the other one is restricted to expression in testis. We named the abundant type AMSH-FPalpha and the testis type AMSH-FPbeta. AMSH-FPbeta is a variant lacking N-terminal 166 amino acid residues of AMSH-FPalpha. Analysis of the 5(')-untranslated regions in AMSH-FPalpha and AMSH-FPbeta mRNAs and exon-intron structure of AMSH-FP gene suggests that testis-specific transcripts are generated due to alternative promoter usage and/or alternative splicing. Importantly, AMSH-FPbeta mRNA was not detected in juvenile and infertile mouse testis but was restrictively expressed in the haploid stage of testicular germ cells in the normal mature testis. We suggested that AMSH-FPbeta had a functional role in the spermiogenesis.
Collapse
Affiliation(s)
- Keiko Kitajima
- Division of Molecular Regenerative Medicine, Course of Advanced Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | | | | | | | | | | |
Collapse
|
20
|
Lundgren J, Masson P, Realini CA, Young P. Use of RNA interference and complementation to study the function of the Drosophila and human 26S proteasome subunit S13. Mol Cell Biol 2003; 23:5320-30. [PMID: 12861018 PMCID: PMC165711 DOI: 10.1128/mcb.23.15.5320-5330.2003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The S13 subunit (also called Pad1, Rpn11, and MPR1) is a component of the 19S complex, a regulatory complex essential for the ubiquitin-dependent proteolytic activity of the 26S proteasome. To address the functional role of S13, we combined double-stranded RNA interference (RNAi) against the Drosophila proteasome subunit DmS13 with expression of wild-type and mutant forms of the homologous human gene, HS13. These studies show that DmS13 is essential for 26S function. Loss of the S13 subunit in metazoan cells leads to increased levels of ubiquitin conjugates, cell cycle defects, DNA overreplication, and apoptosis. In vivo assays using short-lived proteasome substrates confirmed that the 26S ubiquitin-dependent degradation pathway is compromised in S13-depleted cells. In complementation experiments using Drosophila cell lines expressing HS13, wild-type HS13 was found to fully rescue the knockdown phenotype after DmS13 RNAi treatment, while an HS13 containing mutations (H113A-H115A) in the proposed isopeptidase active site was unable to rescue. A mutation within the conserved MPN/JAMM domain (C120A) abolished the ability of HS13 to rescue the Drosophila cells from apoptosis or DNA overreplication. However, the C120A mutant was found to partially restore normal levels of ubiquitin conjugates. The S13 subunit may possess multiple functions, including a deubiquitinylating activity and distinct activities essential for cell cycle progression that require the conserved C120 residue.
Collapse
Affiliation(s)
- Josefin Lundgren
- Department of Molecular Biology and Functional Genetics, Stockholm University, S-10691 Stockholm, Sweden
| | | | | | | |
Collapse
|
21
|
Li Z, Wang CC. Functional characterization of the 11 non-ATPase subunit proteins in the trypanosome 19 S proteasomal regulatory complex. J Biol Chem 2002; 277:42686-93. [PMID: 12213827 DOI: 10.1074/jbc.m207183200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ubiquitin-proteasome pathway is responsible for selective degradation of short-lived and dysfunctional proteins in eukaryotes. The recently demonstrated presence of a functional 26 S proteasome in Trypanosoma brucei led to the identification and isolation of genes encoding all 11 non-ATPase (Rpn) subunit proteins in the trypanosome 19 S regulatory complex. Using the technique of RNA interference, expression of individual RPN genes was disrupted in the procyclic form of T. brucei, resulting, in each case, in intracellular accumulation of polyubiquitinated protein, cell arrest at the G2/M phase, and eventual cell death. With the exception of Rpn10, depletion of individual Rpn proteins disrupted also trypanosome 19 S complex formation, with the complex virtually depleted in the cell lysate. This functional and structural essentiality of 10 of the 11 Rpn proteins in T. brucei differs significantly from that observed in other organisms. When Rpn10 was deficient in trypanosomes, a 19 S complex without Rpn10 was still formed, whereas cell growth was arrested. This structural dispensability but functional indispensability of Rpn10 may constitute another unique aspect of the proteasomes in T. brucei.
Collapse
Affiliation(s)
- Ziyin Li
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143-0446, USA
| | | |
Collapse
|
22
|
Verma R, Aravind L, Oania R, McDonald WH, Yates JR, Koonin EV, Deshaies RJ. Role of Rpn11 metalloprotease in deubiquitination and degradation by the 26S proteasome. Science 2002; 298:611-5. [PMID: 12183636 DOI: 10.1126/science.1075898] [Citation(s) in RCA: 767] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The 26S proteasome mediates degradation of ubiquitin-conjugated proteins. Although ubiquitin is recycled from proteasome substrates, the molecular basis of deubiquitination at the proteasome and its relation to substrate degradation remain unknown. The Rpn11 subunit of the proteasome lid subcomplex contains a highly conserved Jab1/MPN domain-associated metalloisopeptidase (JAMM) motif-EX(n)HXHX(10)D. Mutation of the predicted active-site histidines to alanine (rpn11AXA) was lethal and stabilized ubiquitin pathway substrates in yeast. Rpn11(AXA) mutant proteasomes assembled normally but failed to either deubiquitinate or degrade ubiquitinated Sic1 in vitro. Our findings reveal an unexpected coupling between substrate deubiquitination and degradation and suggest a unifying rationale for the presence of the lid in eukaryotic proteasomes.
Collapse
Affiliation(s)
- Rati Verma
- Department of Biology and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Abstract
We report the cloning and functional analysis of a Pad1 homologue (SmPOH) from Schistosoma mansoni. SmPOH encodes a protein of approximately 35 kDa with high amino acid identities to yeast Pad1 (65%) and its human homologue, POH1 (78%). Members of the Pad1 family are subunits of the 26S proteasome and have been implicated as positive modulators of transcription in yeast. Recombinant SmPOH expressed in COS7 cells exhibited a punctate pattern of distribution throughout the cytoplasm and nucleus, predominantly in the nuclear periphery, a distribution consistent with that of the cellular proteasome. Transient overexpression of SmPOH in COS7 cells caused a dose-dependent stimulation in AP-1 transcriptional activity, as determined by a reporter gene assay. This effect was associated with a pronounced increase in the levels of cellular c-Jun. In vitro degradation assays further demonstrated that SmPOH specifically decreased the rate of c-Jun degradation in a dose dependent manner. Taken together, these results suggest that SmPOH, and possibly other related Pad1 proteins, function as positive modulators of transcription by increasing the stability of cellular c-Jun, making elevated amounts of this protein available for transactivation of AP-1-responsive genes.
Collapse
Affiliation(s)
- Joseph F Nabhan
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, Québec, Canada
| | | | | |
Collapse
|
24
|
Abstract
We report the cloning and functional analysis of a Pad1 homologue (SmPOH) from Schistosoma mansoni. SmPOH encodes a protein of approximately 35 kDa with high amino acid identities to yeast Pad1 (65%) and its human homologue, POH1 (78%). Members of the Pad1 family are subunits of the 26S proteasome and have been implicated as positive modulators of transcription in yeast. Recombinant SmPOH expressed in COS7 cells exhibited a punctate pattern of distribution throughout the cytoplasm and nucleus, predominantly in the nuclear periphery, a distribution consistent with that of the cellular proteasome. Transient overexpression of SmPOH in COS7 cells caused a dose-dependent stimulation in AP-1 transcriptional activity, as determined by a reporter gene assay. This effect was associated with a pronounced increase in the levels of cellular c-Jun. In vitro degradation assays further demonstrated that SmPOH specifically decreased the rate of c-Jun degradation in a dose dependent manner. Taken together, these results suggest that SmPOH, and possibly other related Pad1 proteins, function as positive modulators of transcription by increasing the stability of cellular c-Jun, making elevated amounts of this protein available for transactivation of AP-1-responsive genes.
Collapse
Affiliation(s)
- J F Nabhan
- Institute of Parasitology, McGill University, 21,111 Lakeshore Road, Québec, H9X3V9, Ste. Anne de Bellevue, Canada
| | | | | |
Collapse
|
25
|
Kim T, Hofmann K, von Arnim AG, Chamovitz DA. PCI complexes: pretty complex interactions in diverse signaling pathways. TRENDS IN PLANT SCIENCE 2001; 6:379-386. [PMID: 11495792 DOI: 10.1016/s1360-1385(01)02015-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Three protein complexes (the proteasome regulatory lid, the COP9 signalosome and eukaryotic translation initiation factor 3) contain protein subunits with a well defined protein domain, the PCI domain. At least two (the COP9 signalosome and the lid) appear to share a common evolutionary origin. Recent advances in our understanding of the structure and function of the three complexes point to intriguing and unanticipated connections between the cellular functions performed by these three protein assemblies, especially between translation initiation and proteolytic protein degradation.
Collapse
Affiliation(s)
- T Kim
- Dept Botany, The University of Tennessee, Knoxville TN 37996-1100, USA
| | | | | | | |
Collapse
|
26
|
Abstract
Cells have evolved complex and efficient strategies for dealing with variable and often-harsh environments. A key aspect of these stress responses is the transcriptional activation of genes encoding defense and repair proteins. In yeast members of the AP-1 family of proteins are required for the transcriptional response to oxidative stress. This sub-family of AP-1 (called yAP-1) proteins are sensors of the redox-state of the cell and are activated directly by oxidative stress conditions. yAP-1 proteins are bZIP-containing factors that share homology to the mammalian AP-1 factor complex and bind to very similar DNA sequence sites. The generation of reactive oxygen species and the resulting potential for oxidative stress is common to all aerobically growing organisms. Furthermore, many of the features of this response appear to be evolutionarily conserved and consequently the study of model organisms, such as yeast, will have widespread utility. The important structural features of these factors, signaling pathways controlling their activity and the nature of the target genes they control will be discussed.
Collapse
Affiliation(s)
- W M Toone
- CRC Cell Regulation Group, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Wilmslow Road, Manchester M20 4BX, UK
| | | | | |
Collapse
|
27
|
Stitzel ML, Durso R, Reese JC. The proteasome regulates the UV-induced activation of the AP-1-like transcription factor Gcn4. Genes Dev 2001; 15:128-33. [PMID: 11157770 PMCID: PMC312615 DOI: 10.1101/gad.863801] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The proteasome is well known for its regulation of the cell cycle and degradation of mis-folded proteins, yet many of its functions are still unknown. We show that RPN11, a gene encoding a subunit of the regulatory cap of the proteasome, is required for UV-stimulated activation of Gcn4p target genes, but is dispensable for their activation by the general control pathway. We provide evidence that RPN11 functions downstream of RAS2, and show that mutation of two additional proteasome subunits results in identical phenotypes. Our analysis defines a novel function of the proteasome: regulation of the RAS- and AP-1 transcription factor-dependent UV resistance pathway.
Collapse
Affiliation(s)
- M L Stitzel
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | | |
Collapse
|
28
|
Sakurai H, Ishihama A. Transcription organization and mRNA levels of the genes for all 12 subunits of the fission yeast RNA polymerase II. Genes Cells 2001; 6:25-36. [PMID: 11168594 DOI: 10.1046/j.1365-2443.2001.00394.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The RNA polymerase II (Pol II) of eukaryotes is composed of 12 subunits, of which five are shared among Pol I, Pol II and Pol III. At present, however, little is known about the regulation of synthesis and assembly of the 12 Pol II subunits. To obtain an insight into the regulation of synthesis of these 12 Pol II subunits, Rpb1 to Rpb12, in the fission yeast Schizosaccharomyces pombe, we analysed the transcriptional organization of the rpb genes by use of the oligo capping method, and determined mRNA levels by quantitative competitive PCR assay. The intracellular concentrations of the 12 Rpb subunits in growing S. pombe cells are different, within a range of 15-fold difference between the least abundant Rpb3 and the most abundant Rpb12. The transcription of one group of genes including rpb3, rpb4, rpb5, rpb6, rpb7 and rpb10 is mainly initiated at a single site, while that of the other group of genes for rpb1, rpb2, rpb8, rpb9, rpb11 and rpb12 is initiated at multiple sites. The promoters of the first group of genes contain the TATA box sequence between -26 and -62, while the second group of genes carry TATA-less promoters. Several common sequence segments, tentatively designated 'Rpb motifs', were identified in the promoter regions of the rpb genes. Competitive PCR analysis indicated that mRNAs for Rpb1, Rpb3, Rpb7 and Rpb9 were among the group which had a low abundance, while the levels of Rpb6 and Rpb10 mRNAs were about fivefold, and that of Rpb2 mRNA was about 40-fold higher than the Rpb3 mRNA level. The levels of rpb mRNAs do not correlate with those of Rpb proteins. The protein-to-mRNA ratio or the translation efficiency is low for the rpb1, rpb2, rpb3 and rpb11 genes, encoding the homologues of subunits beta', beta, alpha and alpha, respectively, of the prokaryotic RNA polymerase core enzyme.
Collapse
Affiliation(s)
- H Sakurai
- National Institute of Genetics, Department of Molecular Genetics, Mishima, Shizuoka 411-8540, Japan
| | | |
Collapse
|
29
|
Schwechheimer C, Deng XW. The COP/DET/FUS proteins-regulators of eukaryotic growth and development. Semin Cell Dev Biol 2000; 11:495-503. [PMID: 11145879 DOI: 10.1006/scdb.2000.0203] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eleven recessive mutant loci define the class of cop / det / fus mutants of Arabidopsis. The cop / det / fus mutants mimic the phenotype of light-grown seedlings when grown in the dark. At least four cop / det / fus mutants carry mutations in subunits of the COP9 signalosome, a multiprotein complex paralogous to the 'lid' subcomplex of the 26S proteasome. COP1, another COP/DET/FUS protein, is itself not a subunit of the COP9 signalosome. In the dark, COP1 accumulates in the nucleus where it is required for the degradation of the HY5 protein, a positive regulator of photomorphogenesis. In the light, COP1 is excluded from the nucleus and the constitutively nuclear HY5 protein can accumulate. Nuclear accumulation of COP1 and degradation of HY5 are impaired in the cop / det / fus mutants that carry mutations in subunits of the COP9 signalosome. Although the cellular function of the COP/DET/FUS proteins is not yet well understood, taken together the current findings suggest that the COP/DET/FUS proteins repress photomorphogenesis in the dark by mediating specific protein degradation.
Collapse
Affiliation(s)
- C Schwechheimer
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8104, USA
| | | |
Collapse
|
30
|
Crane R, Craig R, Murray R, Dunand-Sauthier I, Humphrey T, Norbury C. A fission yeast homolog of Int-6, the mammalian oncoprotein and eIF3 subunit, induces drug resistance when overexpressed. Mol Biol Cell 2000; 11:3993-4003. [PMID: 11071922 PMCID: PMC15052 DOI: 10.1091/mbc.11.11.3993] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Through a screen to identify genes that induce multi-drug resistance when overexpressed, we have identified a fission yeast homolog of Int-6, a component of the human translation initiation factor eIF3. Disruption of the murine Int-6 gene by mouse mammary tumor virus (MMTV) has been implicated previously in tumorigenesis, although the underlying mechanism is not yet understood. Fission yeast Int6 was shown to interact with other presumptive components of eIF3 in vivo, and was present in size fractions consistent with its incorporation into a 43S translation preinitiation complex. Drug resistance induced by Int6 overexpression was dependent on the AP-1 transcription factor Pap1, and was associated with increased abundance of Pap1-responsive mRNAs, but not with Pap1 relocalization. Fission yeast cells lacking the int6 gene grew slowly. This growth retardation could be corrected by the expression of full length Int6 of fission yeast or human origin, or by a C-terminal fragment of the fission yeast protein that also conferred drug resistance, but not by truncated human Int-6 proteins corresponding to the predicted products of MMTV-disrupted murine alleles. Studies in fission yeast may therefore help to explain the ways in which Int-6 function can be perturbed during MMTV-induced mammary tumorigenesis.
Collapse
Affiliation(s)
- R Crane
- Imperial Cancer Research Fund, Molecular Oncology Laboratory, University of Oxford, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | | | | | | | | | | |
Collapse
|
31
|
Tabb MM, Tongaonkar P, Vu L, Nomura M. Evidence for separable functions of Srp1p, the yeast homolog of importin alpha (Karyopherin alpha): role for Srp1p and Sts1p in protein degradation. Mol Cell Biol 2000; 20:6062-73. [PMID: 10913188 PMCID: PMC86082 DOI: 10.1128/mcb.20.16.6062-6073.2000] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Srp1p (importin alpha) functions as the nuclear localization signal (NLS) receptor in Saccharomyces cerevisiae. The srp1-31 mutant is defective in this nuclear localization function, whereas an srp1-49 mutant exhibits defects that are unrelated to this localization function, as was confirmed by intragenic complementation between the two mutants. RPN11 and STS1 (DBF8) were identified as high-dosage suppressors of the srp1-49 mutation but not of the srp1-31 mutation. We found that Sts1p interacts directly with Srp1p in vitro and also in vivo, as judged by coimmunoprecipitation and two-hybrid analyses. Mutants of Sts1p that cannot interact with Srp1p are incapable of suppressing srp1-49 defects, strongly suggesting that Sts1p functions in a complex with Srp1p. STS1 also interacted with the second suppressor, RPN11, a subunit of the 26S proteasome, in the two-hybrid system. Further, degradation of Ub-Pro-beta-galactosidase, a test substrate for the ubiquitin-proteasome system, was defective in srp1-49 but not in srp1-31. This defect in protein degradation was alleviated by overexpression of either RPN11 or STS1 in srp1-49. These results suggest a role for Srp1p in regulation of protein degradation separate from its well-established role as the NLS receptor.
Collapse
Affiliation(s)
- M M Tabb
- Departments of Microbiology and Molecular Genetics and Biological Chemistry, University of California, Irvine, Irvine, California 92697-1700, USA
| | | | | | | |
Collapse
|
32
|
Voges D, Zwickl P, Baumeister W. The 26S proteasome: a molecular machine designed for controlled proteolysis. Annu Rev Biochem 2000; 68:1015-68. [PMID: 10872471 DOI: 10.1146/annurev.biochem.68.1.1015] [Citation(s) in RCA: 1377] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In eukaryotic cells, most proteins in the cytosol and nucleus are degraded via the ubiquitin-proteasome pathway. The 26S proteasome is a 2.5-MDa molecular machine built from approximately 31 different subunits, which catalyzes protein degradation. It contains a barrel-shaped proteolytic core complex (the 20S proteasome), capped at one or both ends by 19S regulatory complexes, which recognize ubiquitinated proteins. The regulatory complexes are also implicated in unfolding and translocation of ubiquitinated targets into the interior of the 20S complex, where they are degraded to oligopeptides. Structure, assembly and enzymatic mechanism of the 20S complex have been elucidated, but the functional organization of the 19S complex is less well understood. Most subunits of the 19S complex have been identified, however, specific functions have been assigned to only a few. A low-resolution structure of the 26S proteasome has been obtained by electron microscopy, but the precise arrangement of subunits in the 19S complex is unclear.
Collapse
Affiliation(s)
- D Voges
- Max-Planck-Institut für Biochemie, Martinsried, Germany
| | | | | |
Collapse
|
33
|
Ta M, Vrati S. Mov34 protein from mouse brain interacts with the 3' noncoding region of Japanese encephalitis virus. J Virol 2000; 74:5108-15. [PMID: 10799585 PMCID: PMC110863 DOI: 10.1128/jvi.74.11.5108-5115.2000] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The plus-sense RNA genome of Japanese encephalitis virus (JEV) contains noncoding regions (NCRs) of 95 and 585 bases at its 5' and 3' ends, respectively. The last 83 nucleotides of the 3'-NCR are predicted to form stable stem-loop (SL) structures. The shape of this 3'-SL structure is highly conserved among divergent flaviviruses even though only small stretches of nucleotide sequence contained within these structures are conserved. These SL structures have been predicted to function as cis-acting signals for RNA replication and as such may bind to viral and cellular proteins that may be involved in viral replication. We have studied the interaction of the JEV 3'-NCR RNA with host proteins using gel retardation assays. We show that the JEV 3'-SL structure RNA forms three complexes with proteins from the S100 cytoplasmic extract prepared from the neonatal mouse brain. These complexes could be obtained in the presence of 200 mM KCl, indicating that the RNA-protein interaction may be physiologically relevant. UV-induced cross-linking and Northwestern blotting analyses detected three proteins with apparent molecular masses of 32, 35, and 50 kDa that bound to the JEV 3'-SL structure RNA. Screening of the neonatal mouse brain cDNA library with the JEV 3'-SL structure RNA identified a 36-kDa Mov34 protein interacting with it. Competition experiments using the RNA extracted from JEV virions established that the 36-kDa Mov34 protein indeed bound to the JEV genome. Murine Mov34 belongs to a family of proteins whose members have been shown to be involved in RNA transcription and translation. It is, therefore, likely that the murine Mov34 interaction with JEV 3'-NCR has a role in RNA replication.
Collapse
Affiliation(s)
- M Ta
- National Institute of Immunology, New Delhi-110 067, India
| | | |
Collapse
|
34
|
Chauchereau A, Georgiakaki M, Perrin-Wolff M, Milgrom E, Loosfelt H. JAB1 interacts with both the progesterone receptor and SRC-1. J Biol Chem 2000; 275:8540-8. [PMID: 10722692 DOI: 10.1074/jbc.275.12.8540] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
JAB1 (Jun activation domain-binding protein-1) has previously been described as a coactivator of AP1 transcription factor. We show here, by yeast and mammalian two-hybrid analyses and by pull-down experiments, that JAB1 also interacts with both the progesterone receptor (PR) and the steroid receptor coactivator 1 (SRC-1) and that it stabilizes PR-SRC-1 complexes. We also show that JAB1 potentiates the activity of a variety of transcription factors known to associate with SRC-1 (nuclear receptors, activator protein-1, and nuclear factor kappaB). This occurs without any modification of PR or SRC-1 concentration. JAB1 is a subunit of a large multiprotein complex that has been called the COP9 signalosome. The latter is present in plant and animal cells and has been shown to be involved in a variety of cellular mechanisms including transcription regulation, cell cycle control, and phosphorylation cascades. We now show that it is also involved in the mechanisms of action of nuclear receptors and of their coactivators.
Collapse
Affiliation(s)
- A Chauchereau
- INSERM U 135 Hormones, Genes et Reproduction, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin Bicêtre, France
| | | | | | | | | |
Collapse
|
35
|
Wilkinson CR, Penney M, McGurk G, Wallace M, Gordon C. The 26S proteasome of the fission yeast Schizosaccharomyces pombe. Philos Trans R Soc Lond B Biol Sci 1999; 354:1523-32. [PMID: 10582238 PMCID: PMC1692671 DOI: 10.1098/rstb.1999.0496] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The 26S proteasome is the multiprotein complex that degrades proteins that have been marked for destruction by the ubiquitin pathway. It is made up of two multisubunit complexes, the 20S catalytic core and the 19S regulatory complex. We describe the isolation and characterization of conditional mutants in the regulatory complex and their use to investigate interactions between different subunits. In addition we have investigated the localization of the 26S proteasome in fission yeast, by immunofluorescence in fixed cells and live cells with the use of a GFP-tagged subunit. Surprisingly, we find that in mitotic cells the 26S proteasome occupies a discrete intracellular compartment, the nuclear periphery. Electron microscopic analysis demonstrates that the complex resides inside the nuclear envelope. During meiosis the localization showed a more dynamic distribution. In meiosis I the proteasome remained around the nuclear periphery. However, during meiosis II there was a dramatic relocalization: initially, the signal occupied the area between the dividing nuclei, but at the end of mitosis the signal dispersed, returning to the nuclear periphery on ascospore formation. This observation implies that the nuclear periphery is a major site of proteolysis in yeast during mitotic growth and raises important questions about the function of the 26S proteasome in protein degradation.
Collapse
Affiliation(s)
- C R Wilkinson
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, UK
| | | | | | | | | |
Collapse
|
36
|
Tanaka N, Kaneko K, Asao H, Kasai H, Endo Y, Fujita T, Takeshita T, Sugamura K. Possible involvement of a novel STAM-associated molecule "AMSH" in intracellular signal transduction mediated by cytokines. J Biol Chem 1999; 274:19129-35. [PMID: 10383417 DOI: 10.1074/jbc.274.27.19129] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
STAM containing an SH3 (Src homology 3) domain and an immunoreceptor tyrosine-based activation motif was previously revealed to be implicated in signaling pathways immediately downstream of Jak2 and Jak3 tyrosine kinases associated with cytokine receptors. We molecularly cloned a novel molecule interacting with the SH3 domain of STAM, which was named AMSH (associated molecule with the SH3 domain of STAM). AMSH contains a putative bipartite nuclear localization signal and a homologous region of a c-Jun activation domain-binding protein 1 (JAB1) subdomain in addition to a binding site for the SH3 domain of STAM. AMSH mutant deleted of the C-terminal half conferred dominant negative effects on signaling for DNA synthesis and c-myc induction mediated by interleukin 2 and granulocyte macrophage-colony-stimulating factor. These results suggest that AMSH plays a critical role in the cytokine-mediated intracellular signal transduction downstream of the Jak2/Jak3.STAM complex.
Collapse
Affiliation(s)
- N Tanaka
- Department of Microbiology and Immunology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Javerzat JP, McGurk G, Cranston G, Barreau C, Bernard P, Gordon C, Allshire R. Defects in components of the proteasome enhance transcriptional silencing at fission yeast centromeres and impair chromosome segregation. Mol Cell Biol 1999; 19:5155-65. [PMID: 10373564 PMCID: PMC84358 DOI: 10.1128/mcb.19.7.5155] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fission yeast centromeres are transcriptionally silent and form a heterochromatin-like structure essential for normal centromere function; this appears analogous to heterochromatin and position effect variegation in other eukaryotes. Conditional mutations in three genes designated cep (centromere enhancer of position effect) were found to enhance transcriptional silencing within centromeres. Cloning of the cep1(+) and cep2(+) genes by functional complementation revealed that they are identical to the previously described genes pad1(+) and mts2(+), respectively, which both encode subunits of the proteasome 19S cap. Like Mts2 and Mts4, epitope-tagged Cep1/Pad1 localizes to or near the nuclear envelope throughout the cell cycle. The cep mutants display a range of phenotypes depending on the temperature. Silencing within the central domain of centromeres is increased at 36 degrees C. This suggests that the proteasome is involved in regulating silencing and thus centromeric chromatin architecture, possibly by lowering the level of some chromatin-associated protein by ubiquitin-dependent degradation. This is the first report of defective proteasome function affecting heterochromatin-mediated transcriptional silencing. At 36 and 32 degrees C, the cep mutants lose chromosomes at an elevated rate, and at 18 degrees C, the mutants are cryosensitive for growth. Cytological analysis at 18 degrees C revealed a defect in sister chromatid separation while other mitotic events occurred normally, indicating that cep mutations might interfere specifically with the degradation of inhibitor(s) of sister chromatid separation. These observations suggest that 19S subunits confer a level of substrate specificity on the proteasome and raise the possibility of a link between components involved in centromere architecture and sister chromatid cohesion.
Collapse
Affiliation(s)
- J P Javerzat
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, Scotland, United Kingdom.
| | | | | | | | | | | | | |
Collapse
|
38
|
Cunha AF, Sousa MV, Silva SP, JesuIno RSA, Soares CMA, Felipe MSS. Identification, N-terminal region sequencing and similarity analysis of differentially expressed proteins in Paracoccidioides brasiliensis. Med Mycol 1999. [DOI: 10.1046/j.1365-280x.1999.00211.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
39
|
Wang SW, Norbury C, Harris AL, Toda T. Caffeine can override the S-M checkpoint in fission yeast. J Cell Sci 1999; 112 ( Pt 6):927-37. [PMID: 10036242 DOI: 10.1242/jcs.112.6.927] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The replication checkpoint (or ‘S-M checkpoint’) control prevents progression into mitosis when DNA replication is incomplete. Caffeine has been known for some time to have the capacity to override the S-M checkpoint in animal cells. We show here that caffeine also disrupts the S-M checkpoint in the fission yeast Schizosaccharomyces pombe. By contrast, no comparable effects of caffeine on the S. pombe DNA damage checkpoint were seen. S. pombe cells arrested in early S phase and then exposed to caffeine lost viability rapidly as they attempted to enter mitosis, which was accompanied by tyrosine dephosphorylation of Cdc2. Despite this, the caffeine-induced loss of viability was not blocked in a temperature-sensitive cdc2 mutant incubated at the restrictive temperature, although catastrophic mitosis was prevented under these conditions. This suggests that, in addition to S-M checkpoint control, a caffeine-sensitive function may be important for maintenance of cell viability during S phase arrest. The lethality of a combination of caffeine with the DNA replication inhibitor hydroxyurea was suppressed by overexpression of Cds1 or Chk1, protein kinases previously implicated in S-M checkpoint control and recovery from S phase arrest. In addition, the same combination of drugs was specifically tolerated in cells overexpressing either of two novel S. pombe genes isolated in a cDNA library screen. These findings should allow further molecular investigation of the regulation of S phase arrest, and may provide a useful system with which to identify novel drugs that specifically abrogate the checkpoint control.
Collapse
Affiliation(s)
- S W Wang
- Imperial Cancer Research Fund, Cell Regulation Laboratory, PO Box 123, Lincoln's Inn Fields, London WC2 A3P, UK
| | | | | | | |
Collapse
|
40
|
Perkins EL, Sterling JF, Hashem VI, Resnick MA. Yeast and human genes that affect the Escherichia coli SOS response. Proc Natl Acad Sci U S A 1999; 96:2204-9. [PMID: 10051619 PMCID: PMC26761 DOI: 10.1073/pnas.96.5.2204] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The sequencing of the human genome has led to the identification of many genes whose functions remain to be determined. Because of conservation of genetic function, microbial systems have often been used for identification and characterization of human genes. We have investigated the use of the Escherichia coli SOS induction assay as a screen for yeast and human genes that might play a role in DNA metabolism and/or in genome stability. The SOS system has previously been used to analyze bacterial and viral genes that directly modify DNA. An initial screen of meiotically expressed yeast genes revealed several genes associated with chromosome metabolism (e.g., RAD51 and HHT1 as well as others). The SOS induction assay was then extended to the isolation of human genes. Several known human genes involved in DNA metabolism, such as the Ku70 end-binding protein and DNA ligase IV, were identified, as well as a large number of previously unknown genes. Thus, the SOS assay can be used to identify and characterize human genes, many of which may participate in chromosome metabolism.
Collapse
Affiliation(s)
- E L Perkins
- Chromosome Stability Group, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | | | | | | |
Collapse
|
41
|
Cunha A, Sousa M, Silva S, Jesuíno R, Soares C, Felipe M. Identification, N-terminal region sequencing and similarity analysis of differentially expressed proteins inParacoccidioides brasiliensis. Med Mycol 1999. [DOI: 10.1080/02681219980000181] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
|
42
|
Affiliation(s)
- J Davey
- Department of Biological Sciences, University of Warwick, U.K.
| |
Collapse
|
43
|
Rinaldi T, Ricci C, Porro D, Bolotin-Fukuhara M, Frontali L. A mutation in a novel yeast proteasomal gene, RPN11/MPR1, produces a cell cycle arrest, overreplication of nuclear and mitochondrial DNA, and an altered mitochondrial morphology. Mol Biol Cell 1998; 9:2917-31. [PMID: 9763452 PMCID: PMC25568 DOI: 10.1091/mbc.9.10.2917] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We report here the functional characterization of an essential Saccharomyces cerevisiae gene, MPR1, coding for a regulatory proteasomal subunit for which the name Rpn11p has been proposed. For this study we made use of the mpr1-1 mutation that causes the following pleiotropic defects. At 24 degreesC growth is delayed on glucose and impaired on glycerol, whereas no growth is seen at 36 degreesC on either carbon source. Microscopic observation of cells growing on glucose at 24 degreesC shows that most of them bear a large bud, whereas mitochondrial morphology is profoundly altered. A shift to the nonpermissive temperature produces aberrant elongated cell morphologies, whereas the nucleus fails to divide. Flow cytometry profiles after the shift to the nonpermissive temperature indicate overreplication of both nuclear and mitochondrial DNA. Consistently with the identification of Mpr1p with a proteasomal subunit, the mutation is complemented by the human POH1 proteasomal gene. Moreover, the mpr1-1 mutant grown to stationary phase accumulates ubiquitinated proteins. Localization of the Rpn11p/Mpr1p protein has been studied by green fluorescent protein fusion, and the fusion protein has been found to be mainly associated to cytoplasmic structures. For the first time, a proteasomal mutation has also revealed an associated mitochondrial phenotype. We actually showed, by the use of [rho degrees] cells derived from the mutant, that the increase in DNA content per cell is due in part to an increase in the amount of mitochondrial DNA. Moreover, microscopy of mpr1-1 cells grown on glucose showed that multiple punctate mitochondrial structures were present in place of the tubular network found in the wild-type strain. These data strongly suggest that mpr1-1 is a valuable tool with which to study the possible roles of proteasomal function in mitochondrial biogenesis.
Collapse
Affiliation(s)
- T Rinaldi
- Pasteur Institute-Cenci Bolognetti Foundation, Department of Cell and Developmental Biology, University of Rome "La Sapienza", 00185 Rome, Italy. Rinaldit.axcasp.caspur.it
| | | | | | | | | |
Collapse
|
44
|
Penney M, Wilkinson C, Wallace M, Javerzat JP, Ferrell K, Seeger M, Dubiel W, McKay S, Allshire R, Gordon C. The Pad1+ gene encodes a subunit of the 26 S proteasome in fission yeast. J Biol Chem 1998; 273:23938-45. [PMID: 9727008 DOI: 10.1074/jbc.273.37.23938] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have isolated a fission yeast mutant, mts5-1, in a screen for mutations that confer both methyl 2-benzimidazolecarbamate resistance (MBCR) and temperature sensitivity (ts) on Schizosaccharomyces pombe. This screen has previously isolated mutations in the 26 S proteasome subunits Mts2, Mts3, and Mts4. We show that the mutation in the mts5-1 strain occurs in the pad1(+) gene. pad1(+) was originally isolated on a multicopy plasmid that was capable of conferring staurosporine resistance on a wild type strain. mts5-1/pad1-1 has a similar phenotype to 26 S proteasome mutants previously isolated in the same screen and we show that Pad1 interacts genetically with two of these subunits, Mts3 and Mts4. In this study we describe the identification of Pad1 as a subunit of the 26 S proteasome in fission yeast.
Collapse
Affiliation(s)
- M Penney
- MRC Human Genetics Unit Western General Hospital, Edinburgh EH4 2XU Scotland, United Kingdom
| | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Godon C, Lagniel G, Lee J, Buhler JM, Kieffer S, Perrot M, Boucherie H, Toledano MB, Labarre J. The H2O2 stimulon in Saccharomyces cerevisiae. J Biol Chem 1998; 273:22480-9. [PMID: 9712873 DOI: 10.1074/jbc.273.35.22480] [Citation(s) in RCA: 472] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The changes in gene expression underlying the yeast adaptive stress response to H2O2 were analyzed by comparative two-dimensional gel electrophoresis of total cell proteins. The synthesis of at least 115 proteins is stimulated by H2O2, whereas 52 other proteins are repressed by this treatment. We have identified 71 of the stimulated and 44 of the repressed targets. The kinetics and dose-response parameters of the H2O2 genomic response were also analyzed. Identification of these proteins and their mapping into specific cellular processes give a distinct picture of the way in which yeast cells adapt to oxidative stress. As expected, H2O2-responsive targets include an important number of heat shock proteins and proteins with reactive oxygen intermediate scavenging activities. Exposure to H2O2 also results in a slowdown of protein biosynthetic processes and a stimulation of protein degradation pathways. Finally, the most remarkable result inferred from this study is the resetting of carbohydrate metabolism minutes after the exposure to H2O2. Carbohydrate fluxes are redirected to the regeneration of NADPH at the expense of glycolysis. This study represents the first genome-wide characterization of a H2O2-inducible stimulon in a eukaryote.
Collapse
Affiliation(s)
- C Godon
- Service de Biochimie et Génétique Moléculaire, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex, France
| | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Hori T, Kato S, Saeki M, DeMartino GN, Slaughter CA, Takeuchi J, Toh-e A, Tanaka K. cDNA cloning and functional analysis of p28 (Nas6p) and p40.5 (Nas7p), two novel regulatory subunits of the 26S proteasome. Gene 1998; 216:113-22. [PMID: 9714768 DOI: 10.1016/s0378-1119(98)00309-6] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We employed cDNA cloning to deduce the complete primary structures of p28 and p40.5, two novel subunits of PA700 (also called 19S complex), a 700 kDa multisubunit regulatory complex of the human 26S proteasome. These polypeptides consisted of 226 and 376 amino acids with calculated molecular masses of 24428 Da and 42945 Da, and isoelectric points of 5. 68 and 5.46, respectively. Intriguingly, p28 contained five conserved motifs known as 'ankyrin repeats', implying that this subunit may contribute to interaction of the 26S proteasome with other protein(s). Computer-assisted homology analysis revealed high sequence similarities of p28 and p40.5 with yeast proteins, termed Nas6p and Nas7p (non-ATPase subunits 6 and 7), respectively, whose functions are as yet unknown. Disruption of these yeast genes, NAS6 and NAS7, had no effect on cell viability, indicating that neither of the two subunits is essential for proliferation of yeast cells. However, the NAS7, but not NAS6, disruptant cells caused high sensitivity to heat stress, being unable to proliferate at 37 degreesC.
Collapse
MESH Headings
- Adenosine Triphosphatases/genetics
- Amino Acid Sequence
- Amino Acids/analysis
- Animals
- Base Sequence
- Cattle
- Cell Division/genetics
- Cell Division/physiology
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Endopeptidases
- Fungal Proteins/genetics
- Gene Expression Regulation, Enzymologic
- Genes, Fungal/genetics
- Hot Temperature
- Humans
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Peptide Hydrolases/chemistry
- Peptide Hydrolases/genetics
- Proteasome Endopeptidase Complex
- Proteins/chemistry
- Proteins/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Saccharomyces cerevisiae/cytology
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae Proteins
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tissue Distribution
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- T Hori
- The Tokyo Metropolitan Institute of Medical Science, and CREST, Japan Science and Technology Corporation (JST), 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8613, Japan
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Glickman MH, Rubin DM, Fried VA, Finley D. The regulatory particle of the Saccharomyces cerevisiae proteasome. Mol Cell Biol 1998; 18:3149-62. [PMID: 9584156 PMCID: PMC108897 DOI: 10.1128/mcb.18.6.3149] [Citation(s) in RCA: 397] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/1997] [Accepted: 03/09/1998] [Indexed: 02/07/2023] Open
Abstract
The proteasome is a multisubunit protease responsible for degrading proteins conjugated to ubiquitin. The 670-kDa core particle of the proteasome contains the proteolytic active sites, which face an interior chamber within the particle and are thus protected from the cytoplasm. The entry of substrates into this chamber is thought to be governed by the regulatory particle of the proteasome, which covers the presumed channels leading into the interior of the core particle. We have resolved native yeast proteasomes into two electrophoretic variants and have shown that these represent core particles capped with one or two regulatory particles. To determine the subunit composition of the regulatory particle, yeast proteasomes were purified and analyzed by gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Resolution of the individual polypeptides revealed 17 distinct proteins, whose identities were determined by amino acid sequence analysis. Six of the subunits have sequence features of ATPases (Rpt1 to Rpt6). Affinity chromatography was used to purify regulatory particles from various strains, each of which expressed one of the ATPases tagged with hexahistidine. In all cases, multiple untagged ATPases copurified, indicating that the ATPases assembled together into a heteromeric complex. Of the remaining 11 subunits that we have identified (Rpn1 to Rpn3 and Rpn5 to Rpn12), 8 are encoded by previously described genes and 3 are encoded by genes not previously characterized for yeasts. One of the previously unidentified subunits exhibits limited sequence similarity with deubiquitinating enzymes. Overall, regulatory particles from yeasts and mammals are remarkably similar, suggesting that the specific mechanistic features of the proteasome have been closely conserved over the course of evolution.
Collapse
Affiliation(s)
- M H Glickman
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | | | |
Collapse
|
48
|
Toone WM, Kuge S, Samuels M, Morgan BA, Toda T, Jones N. Regulation of the fission yeast transcription factor Pap1 by oxidative stress: requirement for the nuclear export factor Crm1 (Exportin) and the stress-activated MAP kinase Sty1/Spc1. Genes Dev 1998; 12:1453-63. [PMID: 9585505 PMCID: PMC316839 DOI: 10.1101/gad.12.10.1453] [Citation(s) in RCA: 241] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/1998] [Accepted: 03/06/1998] [Indexed: 02/07/2023]
Abstract
The fission yeast Sty1 stress-activated MAP kinase is crucial for the cellular response to a variety of stress conditions. Accordingly, sty1- cells are defective in their response to nutrient limitation, lose viability in stationary phase, and are hypersensitive to osmotic stress, oxidative stress, and UV treatment. Some of these phenotypes are caused by Sty1-dependent regulation of the Atf1 transcription factor, which controls both meiosis-specific and osmotic stress-responsive genes. However, in this report we demonstrate that the cellular response to oxidative stress and to treatment with a variety of cytotoxic agents is the result of Sty1 regulation of the Pap1 transcription factor, a bZip protein with structural and DNA binding similarities to the mammalian c-Jun protein. We show that both Sty1 and Pap1 are required for the expression of a number of genes involved in the oxidative stress response and for the expression of two genes, hba2+/bfr1+ and pmd1+, which encode energy-dependent transport proteins involved in multidrug resistance. Furthermore, we demonstrate that Pap1 is regulated by stress-dependent changes in subcellular localization. On imposition of oxidative stress, the Pap1 protein relocalizes from the cytoplasm to the nucleus in a process that is dependent on the Sty1 kinase. This relocalization is the result of regulated protein export, rather than import, and involves the Crm1 (exportin) nuclear export factor and the dcd1+/pim1+ gene that encodes an Ran nucleotide exchange factor.
Collapse
Affiliation(s)
- W M Toone
- Laboratory of Gene Regulation, Imperial Cancer Research Fund (ICRF), London WC2A 3PX,
| | | | | | | | | | | |
Collapse
|
49
|
Aravind L, Ponting CP. Homologues of 26S proteasome subunits are regulators of transcription and translation. Protein Sci 1998; 7:1250-4. [PMID: 9605331 PMCID: PMC2144014 DOI: 10.1002/pro.5560070521] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Single copies of an alpha-helical-rich motif are demonstrated to be present within subunits of the large multiprotein 26S proteasome and eukaryotic initiation factor-3 (eIF3) complexes, and within proteins involved in transcriptional regulation. In addition, p40 and p47 subunits of eIF3 are shown to be homologues of the proteasome subunit Mov34, and transcriptional regulators JAB1/pad1. Finally, the proteasome subunit S5a and the p44 subunit of the basal transcription factor IIH (TFIIH) are identified as homologues. The presence of homologous, and sometimes identical, proteins in contrasting functional contexts suggests that the large multisubunit complexes of the 26S proteasome, eIF3 and TFIIH perform overlapping cellular roles.
Collapse
Affiliation(s)
- L Aravind
- Department of Biology-BSBW, Texas A&M University, College Station 77843, USA
| | | |
Collapse
|
50
|
Seeger M, Kraft R, Ferrell K, Bech‐Otschir D, Dumdey R, Schade R, Gordon C, Naumann M, Dubiel W. A novel protein complex involved in signal transduction possessing similarities to 26S proteasome subunits. FASEB J 1998. [DOI: 10.1096/fasebj.12.6.469] [Citation(s) in RCA: 265] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Michael Seeger
- Institute of BiochemistryHumboldt‐UniversityMedical Faculty (Charité) Berlin 10117 Germany
| | | | - Katherine Ferrell
- Institute of BiochemistryHumboldt‐UniversityMedical Faculty (Charité) Berlin 10117 Germany
| | | | - Renate Dumdey
- Institute of BiochemistryHumboldt‐UniversityMedical Faculty (Charité) Berlin 10117 Germany
| | - Rüdiger Schade
- Institute of Pharmacology and ToxicologyHumboldt‐UniversityMedical Faculty (Charité) Berlin 10117 Germany
| | - Colin Gordon
- MRC Human Genetics UnitWestern General Hospital Edinburgh EH4 2XU UK
| | - Michael Naumann
- Max‐Planck‐Institut füir Infektionsbiologie Abt. Molekulare Biologie Berlin 10117 Germany
| | - Wolfgang Dubiel
- Institute of BiochemistryHumboldt‐UniversityMedical Faculty (Charité) Berlin 10117 Germany
| |
Collapse
|