1
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Ju D, Wu S, Li L, Xie Y. Ubiquitylation-independent cotranslational degradation of dihydrofolate reductase and ubiquitin. Biochem Biophys Res Commun 2024; 702:149651. [PMID: 38350414 DOI: 10.1016/j.bbrc.2024.149651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 01/31/2024] [Accepted: 02/06/2024] [Indexed: 02/15/2024]
Abstract
Nascent proteins are degraded during or immediately after synthesis, a process called cotranslational protein degradation (CTPD). Although CTPD was observed decades ago, it has never been fully explored mechanistically and functionally. We show here that dihydrofolate reductase (DHFR) and ubiquitin (Ub), two stable proteins widely used in protein degradation studies, are actually subject to CTPD. Unlike canonical posttranslational protein degradation, CTPD of DHFR and Ub does not require prior ubiquitylation. Our data also suggest that protein expression level and N-terminal folding pattern may be two critical determinants for CTPD. Thus, this study reveals that CTPD plays a role in regulating the homeostasis of long-lived proteins and provides insights into the mechanism of CTPD.
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Affiliation(s)
- Donghong Ju
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, 48201, USA; Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, 48201, USA; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, USA; Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Shichao Wu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Li Li
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, USA; Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Youming Xie
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, 48201, USA; Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
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2
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Breckel CA, Johnson ZM, Hickey CM, Hochstrasser M. Yeast 26S proteasome nuclear import is coupled to nucleus-specific degradation of the karyopherin adaptor protein Sts1. Sci Rep 2024; 14:2048. [PMID: 38267508 PMCID: PMC10808114 DOI: 10.1038/s41598-024-52352-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 01/16/2024] [Indexed: 01/26/2024] Open
Abstract
In eukaryotes, the ubiquitin-proteasome system is an essential pathway for protein degradation and cellular homeostasis. 26S proteasomes concentrate in the nucleus of budding yeast Saccharomyces cerevisiae due to the essential import adaptor protein Sts1 and the karyopherin-α protein Srp1. Here, we show that Sts1 facilitates proteasome nuclear import by recruiting proteasomes to the karyopherin-α/β heterodimer. Following nuclear transport, the karyopherin proteins are likely separated from Sts1 through interaction with RanGTP in the nucleus. RanGTP-induced release of Sts1 from the karyopherin proteins initiates Sts1 proteasomal degradation in vitro. Sts1 undergoes karyopherin-mediated nuclear import in the absence of proteasome interaction, but Sts1 degradation in vivo is only observed when proteasomes successfully localize to the nucleus. Sts1 appears to function as a proteasome import factor during exponential growth only, as it is not found in proteasome storage granules (PSGs) during prolonged glucose starvation, nor does it appear to contribute to the rapid nuclear reimport of proteasomes following glucose refeeding and PSG dissipation. We propose that Sts1 acts as a single-turnover proteasome nuclear import factor by recruiting karyopherins for transport and undergoing subsequent RanGTP-initiated ubiquitin-independent proteasomal degradation in the nucleus.
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Affiliation(s)
- Carolyn Allain Breckel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Zane M Johnson
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Christopher M Hickey
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
- Arvinas, Inc., 5 Science Park, New Haven, CT, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, 06520, USA.
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3
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Ju D, Li L, Xie Y. Homeostatic regulation of ribosomal proteins by ubiquitin-independent cotranslational degradation. Proc Natl Acad Sci U S A 2023; 120:e2306152120. [PMID: 37459537 PMCID: PMC10372694 DOI: 10.1073/pnas.2306152120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 06/14/2023] [Indexed: 07/20/2023] Open
Abstract
Ribosomes are the workplace for protein biosynthesis. Protein production required for normal cell function is tightly linked to ribosome abundance. It is well known that ribosomal genes are actively transcribed and ribosomal messenger RNAs (mRNAs) are rapidly translated, and yet ribosomal proteins have relatively long half-lives. These observations raise questions as to how homeostasis of ribosomal proteins is controlled. Here, we show that ribosomal proteins, while posttranslationally stable, are subject to high-level cotranslational protein degradation (CTPD) except for those synthesized as ubiquitin (Ub) fusion precursors. The N-terminal Ub moiety protects fused ribosomal proteins from CTPD. We further demonstrate that cotranslational folding efficiency and expression level are two critical factors determining CTPD of ribosomal proteins. Different from canonical posttranslational degradation, we found that CTPD of all the ribosomal proteins tested in this study does not require prior ubiquitylation. This work provides insights into the regulation of ribosomal protein homeostasis and furthers our understanding of the mechanism and biological significance of CTPD.
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Affiliation(s)
- Donghong Ju
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI48201
- Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI48201
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI48201
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI48201
| | - Li Li
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI48201
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI48201
| | - Youming Xie
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI48201
- Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI48201
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4
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Karpov DS, Spasskaya DS, Tutyaeva VV, Karpov VL. Rpn4p without the DNA-Binding Domain Provides Saccharomyces cerevisiae Resistance to Oxidative Stress and Cycloheximide. Mol Biol 2022. [DOI: 10.1134/s0026893322040057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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5
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Ceballos-Garzon A, Monteoliva L, Gil C, Alvarez-Moreno C, Vega-Vela NE, Engelthaler DM, Bowers J, Le Pape P, Parra-Giraldo CM. Genotypic, proteomic, and phenotypic approaches to decipher the response to caspofungin and calcineurin inhibitors in clinical isolates of echinocandin-resistant Candida glabrata. J Antimicrob Chemother 2021; 77:585-597. [PMID: 34893830 PMCID: PMC8865013 DOI: 10.1093/jac/dkab454] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/09/2021] [Indexed: 01/20/2023] Open
Abstract
Background Echinocandin resistance represents a great concern, as these drugs are recommended as first-line therapy for invasive candidiasis. Echinocandin resistance is conferred by mutations in FKS genes. Nevertheless, pathways are crucial for enabling tolerance, evolution, and maintenance of resistance. Therefore, understanding the biological processes and proteins involved in the response to caspofungin may provide clues indicating new therapeutic targets. Objectives We determined the resistance mechanism and assessed the proteome response to caspofungin exposure. We then evaluated the phenotypic impact of calcineurin inhibition by FK506 and cephalosporine A (CsA) on caspofungin-resistant Candida glabrata isolates. Methods Twenty-five genes associated with caspofungin resistance were analysed by NGS, followed by studies of the quantitative proteomic response to caspofungin exposure. Then, susceptibility testing of caspofungin in presence of FK506 and CsA was performed. The effects of calcineurin inhibitor/caspofungin combinations on heat stress (40°C), oxidative stress (0.2 and 0.4 mM menadione) and on biofilm formation (polyurethane catheter) were analysed. Finally, a Galleria mellonella model using blastospores (1 × 109 cfu/mL) was developed to evaluate the impact of the combinations on larval survival. Results F659-del was found in the FKS2 gene of resistant strains. Proteomics data showed some up-regulated proteins are involved in cell-wall biosynthesis, response to stress and pathogenesis, some of them being members of calmodulin–calcineurin pathway. Therefore, the impact of calmodulin inhibition was explored. Calmodulin inhibition restored caspofungin susceptibility, decreased capacity to respond to stress conditions, and reduced biofilm formation and in vivo pathogenicity. Conclusions Our findings confirm that calmodulin-calcineurin-Crz1 could provide a relevant target in life-threatening invasive candidiasis.
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Affiliation(s)
- Andres Ceballos-Garzon
- Unidad de Proteómica y Micosis Humanas, Grupo de Enfermedades Infecciosas Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
- Department of Parasitology and Medical Mycology, Faculty of Pharmacy, University of Nantes, Nantes Atlantique Universities, Nantes, France
| | - Lucia Monteoliva
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Concha Gil
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
- Unidad de Proteómica, Universidad Complutense de Madrid, Madrid, Spain
| | - Carlos Alvarez-Moreno
- Department of Internal Medicine, Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
- Clínica Universitaria Colombia, Clinica Colsanitas, Bogotá, Colombia
| | - Nelson E Vega-Vela
- Unidad de Proteómica y Micosis Humanas, Grupo de Enfermedades Infecciosas Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
| | | | - Jolene Bowers
- Translational Genomics Research Institute, Flagstaff, AZ, USA
| | - Patrice Le Pape
- Department of Parasitology and Medical Mycology, Faculty of Pharmacy, University of Nantes, Nantes Atlantique Universities, Nantes, France
| | - Claudia M Parra-Giraldo
- Unidad de Proteómica y Micosis Humanas, Grupo de Enfermedades Infecciosas Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
- Corresponding author. E-mail:
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6
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Wang T, Zhang T, Tang Y, Wang H, Wei Q, Lu Y, Yao J, Qu Y, Cao X. Oxysterol-binding protein-like 2 contributes to the developmental progression of preadipocytes by binding to β-catenin. Cell Death Discov 2021; 7:109. [PMID: 34001864 PMCID: PMC8129138 DOI: 10.1038/s41420-021-00503-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 04/28/2021] [Indexed: 02/06/2023] Open
Abstract
Oxysterol-binding protein-like 2 (OSBPL2), also known as oxysterol-binding protein-related protein (ORP) 2, is a member of lipid transfer protein well-known for its role in regulating cholesterol homeostasis. A recent study reported that OSBPL2/ORP2 localizes to lipid droplets (LDs) and is associated with energy metabolism and obesity. However, the function of OSBPL2/ORP2 in adipocyte differentiation is poorly understood. Here, we report that OSBPL2/ORP2 contributes to the developmental progression of preadipocytes. We found that OSBPL2/ORP2 binds to β-catenin, a key effector in the Wnt signaling pathway that inhibits adipogenesis. This complex plays a role in regulating the protein level of β-catenin only in preadipocytes, not in mature adipocytes. Our data further indicated that OSBPL2/ORP2 mediates the transport of β-catenin into the nucleus and thus regulates target genes related to adipocyte differentiation. Deletion of OSBPL2/ORP2 markedly reduces β-catenin both in the cytoplasm and in the nucleus, promotes preadipocytes maturation, and ultimately leads to obesity-related characteristics. Altogether, we provide novel insight into the function of OSBPL2/ORP2 in the developmental progression of preadipocytes and suggest OSBPL2/ORP2 may be a potential therapeutic target for the treatment of obesity-related diseases.
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Affiliation(s)
- Tianming Wang
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Tianyu Zhang
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Youzhi Tang
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Hongshun Wang
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Qinjun Wei
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Yajie Lu
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Jun Yao
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Yuan Qu
- Jiangsu Cancer Hospital, Nanjing Medical University, Nanjing, China
| | - Xin Cao
- Department of Medical Genetics, School of Basic Medical Science, Nanjing Medical University, Nanjing, China. .,Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China.
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7
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Budenholzer L, Breckel C, Hickey CM, Hochstrasser M. The Sts1 nuclear import adapter uses a non-canonical bipartite nuclear localization signal and is directly degraded by the proteasome. J Cell Sci 2020; 133:jcs.236158. [PMID: 32041904 DOI: 10.1242/jcs.236158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/27/2020] [Indexed: 02/06/2023] Open
Abstract
The proteasome is an essential regulator of protein homeostasis. In yeast and many mammalian cells, proteasomes strongly concentrate in the nucleus. Sts1 from the yeast Saccharomyces cerevisiae is an essential protein linked to proteasome nuclear localization. Here, we show that Sts1 contains a non-canonical bipartite nuclear localization signal (NLS) important for both nuclear localization of Sts1 itself and the proteasome. Sts1 binds the karyopherin-α import receptor (Srp1) stoichiometrically, and this requires the NLS. The NLS is essential for viability, and over-expressed Sts1 with an inactive NLS interferes with 26S proteasome import. The Sts1-Srp1 complex binds preferentially to fully assembled 26S proteasomes in vitro Sts1 is itself a rapidly degraded 26S proteasome substrate; notably, this degradation is ubiquitin independent in cells and in vitro and is inhibited by Srp1 binding. Mutants of Sts1 are stabilized, suggesting that its degradation is tightly linked to its role in localizing proteasomes to the nucleus. We propose that Sts1 normally promotes nuclear import of fully assembled proteasomes and is directly degraded by proteasomes without prior ubiquitylation following karyopherin-α release in the nucleus.
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Affiliation(s)
- Lauren Budenholzer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Carolyn Breckel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Christopher M Hickey
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA .,Department of Molecular, Cellular & Developmental Biology, Yale University, New Haven, CT 06520, USA
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8
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Tronchoni J, García-Ríos E, Guillamón JM, Querol A, Pérez-Torrado R. Transcriptomic analysis of Saccharomyces cerevisiae x Saccharomyceskudriavzevii hybrids during low temperature winemaking. F1000Res 2017; 6:679. [PMID: 29067162 PMCID: PMC5635440 DOI: 10.12688/f1000research.11550.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/07/2017] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Although Saccharomyces cerevisiae is the most frequently isolated species in wine fermentation, and the most studied species, other species and interspecific hybrids have greatly attracted the interest of researchers in this field in the last few years, given their potential to solve new winemaking industry challenges. S. cerevisiae x S. kudriavzevii hybrids exhibit good fermentative capabilities at low temperatures, and produce wines with smaller alcohol quantities and larger glycerol quantities, which can be very useful to solve challenges in the winemaking industry such as the necessity to enhance the aroma profile. METHODS In this study, we performed a transcriptomic study of S. cerevisiae x S. kudriavzevii hybrids in low temperature winemaking conditions. RESULTS The results revealed that the hybrids have acquired both fermentative abilities and cold adaptation abilities, attributed to S. cerevisiae and S. kudriavzevii parental species, respectively, showcasing their industrially relevant characteristics. For several key genes, we also studied the contribution to gene expression of each of the alleles of S. cerevisiae and S. kudriavzevii in the S. cerevisiae x S. kudriavzevii hybrids. From the results, it is not clear how important the differential expression of the specific parental alleles is to the phenotype of the hybrids. CONCLUSIONS This study shows that the fermentative abilities of S. cerevisiae x S. kudriavzevii hybrids at low temperatures do not seem to result from differential expression of specific parental alleles of the key genes involved in this phenotype.
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Affiliation(s)
- Jordi Tronchoni
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology (IATA-CSIC), Paterna, Valencia, Spain.,Instituto de Ciencias de la Vid y del Vino (ICVV), Gobierno de La Rioja-CSIC-Universidad de La Rioja, Logroño, La Rioja, Spain
| | - Estéfani García-Ríos
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology (IATA-CSIC), Paterna, Valencia, Spain
| | - Jose Manuel Guillamón
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology (IATA-CSIC), Paterna, Valencia, Spain
| | - Amparo Querol
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology (IATA-CSIC), Paterna, Valencia, Spain
| | - Roberto Pérez-Torrado
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology (IATA-CSIC), Paterna, Valencia, Spain
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9
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Yedidi RS, Fatehi AK, Enenkel C. Proteasome dynamics between proliferation and quiescence stages of Saccharomyces cerevisiae. Crit Rev Biochem Mol Biol 2016; 51:497-512. [PMID: 27677933 DOI: 10.1080/10409238.2016.1230087] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The ubiquitin-proteasome system (UPS) plays a critical role in cellular protein homeostasis and is required for the turnover of short-lived and unwanted proteins, which are targeted by poly-ubiquitination for degradation. Proteasome is the key protease of UPS and consists of multiple subunits, which are organized into a catalytic core particle (CP) and a regulatory particle (RP). In Saccharomyces cerevisiae, proteasome holo-enzymes are engaged in degrading poly-ubiquitinated substrates and are mostly localized in the nucleus during cell proliferation. While in quiescence, the RP and CP are sequestered into motile and reversible storage granules in the cytoplasm, called proteasome storage granules (PSGs). The reversible nature of PSGs allows the proteasomes to be transported back into the nucleus upon exit from quiescence. Nuclear import of RP and CP through nuclear pores occurs via the canonical pathway that includes the importin-αβ heterodimer and takes advantage of the Ran-GTP gradient across the nuclear membrane. Dependent on the growth stage, either inactive precursor complexes or mature holo-enzymes are imported into the nucleus. The present review discusses the dynamics of proteasomes including their assembly, nucleo-cytoplasmic transport during proliferation and the sequestration of proteasomes into PSGs during quiescence. [Formula: see text].
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Affiliation(s)
| | | | - Cordula Enenkel
- a Department of Biochemistry , University of Toronto , Toronto , Canada
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10
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Miyamoto Y, Yamada K, Yoneda Y. Importin α: a key molecule in nuclear transport and non-transport functions. J Biochem 2016; 160:69-75. [DOI: 10.1093/jb/mvw036] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 05/17/2016] [Indexed: 01/02/2023] Open
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11
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Ha SW, Ju D, Hao W, Xie Y. Rapidly Translated Polypeptides Are Preferred Substrates for Cotranslational Protein Degradation. J Biol Chem 2016; 291:9827-34. [PMID: 26961882 DOI: 10.1074/jbc.m116.716175] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Indexed: 11/06/2022] Open
Abstract
Nascent polypeptides are degraded by the proteasome concurrently with their synthesis on the ribosome. This process, called cotranslational protein degradation (CTPD), has been observed for years, but the underlying mechanisms remain poorly understood. Equally unclear are the identities of cellular proteins genuinely subjected to CTPD. Here we report the identification of CTPD substrates in the yeast Saccharomyces cerevisiae via a quantitative proteomic analysis. We compared the abundance of individual ribosome-bound nascent chains between a wild type strain and a mutant defective in CTPD. Of 1,422 proteins acquired from the proteomic analysis, 289 species are efficient CTPD substrates, with >30% of their nascent chains degraded cotranslationally. We found that proteins involved in translation, ribosome biogenesis, nuclear transport, and amino acid metabolism are more likely to be targeted for CTPD. There is a strong correlation between CTPD and the translation efficiency. CTPD occurs preferentially to rapidly translated polypeptides. CTPD is also influenced by the protein sequence length; longer polypeptides are more susceptible to CTPD. In addition, proteins with N-terminal disorder have a higher probability of being degraded cotranslationally. Interestingly, the CTPD efficiency is not related to the half-lives of mature proteins. These results for the first time indicate an inverse correlation between CTPD and cotranslational folding on a proteome scale. The implications of this study with respect to the physiological significance of CTPD are discussed.
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Affiliation(s)
- Seung-Wook Ha
- From the Karmanos Cancer Institute, Department of Oncology, School of Medicine and
| | - Donghong Ju
- From the Karmanos Cancer Institute, Department of Oncology, School of Medicine and
| | - Weilong Hao
- the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48201
| | - Youming Xie
- From the Karmanos Cancer Institute, Department of Oncology, School of Medicine and
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12
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Enenkel C. Nuclear transport of yeast proteasomes. Biomolecules 2014; 4:940-55. [PMID: 25333764 PMCID: PMC4279164 DOI: 10.3390/biom4040940] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/18/2014] [Accepted: 09/26/2014] [Indexed: 12/25/2022] Open
Abstract
Proteasomes are conserved protease complexes enriched in the nuclei of dividing yeast cells, a major site for protein degradation. If yeast cells do not proliferate and transit to quiescence, metabolic changes result in the dissociation of proteasomes into proteolytic core and regulatory complexes and their sequestration into motile cytosolic proteasome storage granuli. These granuli rapidly clear with the resumption of growth, releasing the stored proteasomes, which relocalize back to the nucleus to promote cell cycle progression. Here, I report on three models of how proteasomes are transported from the cytoplasm into the nucleus of yeast cells. The first model applies for dividing yeast and is based on the canonical pathway using classical nuclear localization sequences of proteasomal subcomplexes and the classical import receptor importin/karyopherin αβ. The second model applies for quiescent yeast cells, which resume growth and use Blm10, a HEAT-like repeat protein structurally related to karyopherin β, for nuclear import of proteasome core particles. In the third model, the fully-assembled proteasome is imported into the nucleus. Our still marginal knowledge about proteasome dynamics will inspire the discussion on how protein degradation by proteasomes may be regulated in different cellular compartments of dividing and quiescent eukaryotic cells.
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Affiliation(s)
- Cordula Enenkel
- Department of Biochemistry, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
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13
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Morozov AV, Spasskaya DS, Karpov DS, Karpov VL. The central domain of yeast transcription factor Rpn4 facilitates degradation of reporter protein in human cells. FEBS Lett 2014; 588:3713-9. [PMID: 25157437 DOI: 10.1016/j.febslet.2014.08.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/08/2014] [Accepted: 08/13/2014] [Indexed: 11/29/2022]
Abstract
Despite high interest in the cellular degradation machinery and protein degradation signals (degrons), few degrons with universal activity along species have been identified. It has been shown that fusion of a target protein with a degradation signal from mammalian ornithine decarboxylase (ODC) induces fast proteasomal degradation of the chimera in both mammalian and yeast cells. However, no degrons from yeast-encoded proteins capable to function in mammalian cells were identified so far. Here, we demonstrate that the yeast transcription factor Rpn4 undergoes fast proteasomal degradation and its central domain can destabilize green fluorescent protein and Alpha-fetoprotein in human HEK 293T cells. Furthermore, we confirm the activity of this degron in yeast. Thus, the Rpn4 central domain is an effective interspecies degradation signal.
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Affiliation(s)
- A V Morozov
- W.A. Engelhardt Institute of Molecular Biology RAS, Moscow, Russia.
| | - D S Spasskaya
- W.A. Engelhardt Institute of Molecular Biology RAS, Moscow, Russia
| | - D S Karpov
- W.A. Engelhardt Institute of Molecular Biology RAS, Moscow, Russia
| | - V L Karpov
- W.A. Engelhardt Institute of Molecular Biology RAS, Moscow, Russia
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14
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Boban M, Pantazopoulou M, Schick A, Ljungdahl PO, Foisner R. A nuclear ubiquitin-proteasome pathway targets the inner nuclear membrane protein Asi2 for degradation. J Cell Sci 2014; 127:3603-13. [PMID: 24928896 DOI: 10.1242/jcs.153163] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The nuclear envelope consists of inner and outer nuclear membranes. Whereas the outer membrane is an extension of the endoplasmic reticulum, the inner nuclear membrane (INM) represents a unique membranous environment containing specific proteins. The mechanisms of integral INM protein degradation are unknown. Here, we investigated the turnover of Asi2, an integral INM protein in Saccharomyces cerevisiae. We report that Asi2 is degraded by the proteasome independently of the vacuole and that it exhibited a half-life of ∼45 min. Asi2 exhibits enhanced stability in mutants lacking the E2 ubiquitin conjugating enzymes Ubc6 or Ubc7, or the E3 ubiquitin ligase Doa10. Consistent with these data, Asi2 is post-translationally modified by poly-ubiquitylation in a Ubc7- and Doa10-dependent manner. Importantly Asi2 degradation is significantly reduced in a sts1-2 mutant that fails to accumulate proteasomes in the nucleus, indicating that Asi2 is degraded in the nucleus. Our results reveal a molecular pathway that affects the stability of integral proteins of the inner nuclear membrane and indicate that Asi2 is subject to protein quality control in the nucleus.
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Affiliation(s)
- Mirta Boban
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Marina Pantazopoulou
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Anna Schick
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Per O Ljungdahl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Roland Foisner
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
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Antón LC, Yewdell JW. Translating DRiPs: MHC class I immunosurveillance of pathogens and tumors. J Leukoc Biol 2014; 95:551-62. [PMID: 24532645 PMCID: PMC3958739 DOI: 10.1189/jlb.1113599] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/15/2014] [Accepted: 01/19/2014] [Indexed: 11/24/2022] Open
Abstract
MHC class I molecules display oligopeptides on the cell surface to enable T cell immunosurveillance of intracellular pathogens and tumors. Speed is of the essence in detecting viruses, which can complete a full replication cycle in just hours, whereas tumor detection is typically a finding-the-needle-in-the-haystack exercise. We review current evidence supporting a nonrandom, compartmentalized selection of peptidogenic substrates that focuses on rapidly degraded translation products as a main source of peptide precursors to optimize immunosurveillance of pathogens and tumors.
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Affiliation(s)
- Luis C Antón
- 1.NIAID, NIH, Bldg. 33, Bethesda, MD 20892, USA.
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