1
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Pereira CD, Espadas G, Martins F, Bertrand AT, Servais L, Sabidó E, Chevalier P, da Cruz e Silva OA, Rebelo S. Quantitative proteome analysis of LAP1-deficient human fibroblasts: A pilot approach for predicting the signaling pathways deregulated in LAP1-associated diseases. Biochem Biophys Rep 2024; 39:101757. [PMID: 39035020 PMCID: PMC11260385 DOI: 10.1016/j.bbrep.2024.101757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/11/2024] [Accepted: 06/14/2024] [Indexed: 07/23/2024] Open
Abstract
Lamina-associated polypeptide 1 (LAP1), a ubiquitously expressed nuclear envelope protein, appears to be essential for the maintenance of cell homeostasis. Although rare, mutations in the human LAP1-encoding TOR1AIP1 gene cause severe diseases and can culminate in the premature death of affected individuals. Despite there is increasing evidence of the pathogenicity of TOR1AIP1 mutations, the current knowledge on LAP1's physiological roles in humans is limited; hence, investigation is required to elucidate the critical functions of this protein, which can be achieved by uncovering the molecular consequences of LAP1 depletion, a topic that remains largely unexplored. In this work, the proteome of patient-derived LAP1-deficient fibroblasts carrying a pathological TOR1AIP1 mutation (LAP1 E482A) was quantitatively analyzed to identify global changes in protein abundance levels relatively to control fibroblasts. An in silico functional enrichment analysis of the mass spectrometry-identified differentially expressed proteins was also performed, along with additional in vitro functional assays, to unveil the biological processes that are potentially dysfunctional in LAP1 E482A fibroblasts. Collectively, our findings suggest that LAP1 deficiency may induce significant alterations in various cellular activities, including DNA repair, messenger RNA degradation/translation, proteostasis and glutathione metabolism/antioxidant response. This study sheds light on possible new functions of human LAP1 and could set the basis for subsequent in-depth mechanistic investigations. Moreover, by identifying deregulated signaling pathways in LAP1-deficient cells, our work may offer valuable molecular targets for future disease-modifying therapies for TOR1AIP1-associated nuclear envelopathies.
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Affiliation(s)
- Cátia D. Pereira
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Guadalupe Espadas
- Center for Genomics Regulation, The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
| | - Filipa Martins
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Anne T. Bertrand
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Laurent Servais
- MDUK Oxford Neuromuscular Center, Department of Paediatrics, University of Oxford and NIHR Oxford Biomedical Research Center, Oxford, OX3 9DU, United Kingdom
- Neuromuscular Center, Division of Paediatrics, University Hospital of Liège and University of Liège, 4000, Liège, Belgium
| | - Eduard Sabidó
- Center for Genomics Regulation, The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
| | - Philippe Chevalier
- Université Claude Bernard Lyon 1, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | - Odete A.B. da Cruz e Silva
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Sandra Rebelo
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
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2
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Chen KY, Park H, Subramaniam AR. Massively parallel identification of sequence motifs triggering ribosome-associated mRNA quality control. Nucleic Acids Res 2024; 52:7171-7187. [PMID: 38647082 PMCID: PMC11229359 DOI: 10.1093/nar/gkae285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 02/28/2024] [Accepted: 04/04/2024] [Indexed: 04/25/2024] Open
Abstract
Decay of mRNAs can be triggered by ribosome slowdown at stretches of rare codons or positively charged amino acids. However, the full diversity of sequences that trigger co-translational mRNA decay is poorly understood. To comprehensively identify sequence motifs that trigger mRNA decay, we use a massively parallel reporter assay to measure the effect of all possible combinations of codon pairs on mRNA levels in S. cerevisiae. In addition to known mRNA-destabilizing sequences, we identify several dipeptide repeats whose translation reduces mRNA levels. These include combinations of positively charged and bulky residues, as well as proline-glycine and proline-aspartate dipeptide repeats. Genetic deletion of the ribosome collision sensor Hel2 rescues the mRNA effects of these motifs, suggesting that they trigger ribosome slowdown and activate the ribosome-associated quality control (RQC) pathway. Deep mutational scanning of an mRNA-destabilizing dipeptide repeat reveals a complex interplay between the charge, bulkiness, and location of amino acid residues in conferring mRNA instability. Finally, we show that the mRNA effects of codon pairs are predictive of the effects of endogenous sequences. Our work highlights the complexity of sequence motifs driving co-translational mRNA decay in eukaryotes, and presents a high throughput approach to dissect their requirements at the codon level.
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Affiliation(s)
- Katharine Y Chen
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Heungwon Park
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Arvind Rasi Subramaniam
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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3
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Seinkmane E, Edmondson A, Peak-Chew SY, Zeng A, Rzechorzek NM, James NR, West J, Munns J, Wong DC, Beale AD, O'Neill JS. Circadian regulation of macromolecular complex turnover and proteome renewal. EMBO J 2024; 43:2813-2833. [PMID: 38778155 PMCID: PMC11217436 DOI: 10.1038/s44318-024-00121-5] [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: 11/03/2023] [Revised: 04/04/2024] [Accepted: 04/15/2024] [Indexed: 05/25/2024] Open
Abstract
Although costly to maintain, protein homeostasis is indispensable for normal cellular function and long-term health. In mammalian cells and tissues, daily variation in global protein synthesis has been observed, but its utility and consequences for proteome integrity are not fully understood. Using several different pulse-labelling strategies, here we gain direct insight into the relationship between protein synthesis and abundance proteome-wide. We show that protein degradation varies in-phase with protein synthesis, facilitating rhythms in turnover rather than abundance. This results in daily consolidation of proteome renewal whilst minimising changes in composition. Coupled rhythms in synthesis and turnover are especially salient to the assembly of macromolecular protein complexes, particularly the ribosome, the most abundant species of complex in the cell. Daily turnover and proteasomal degradation rhythms render cells and mice more sensitive to proteotoxic stress at specific times of day, potentially contributing to daily rhythms in the efficacy of proteasomal inhibitors against cancer. Our findings suggest that circadian rhythms function to minimise the bioenergetic cost of protein homeostasis through temporal consolidation of protein turnover.
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Affiliation(s)
- Estere Seinkmane
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Anna Edmondson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Sew Y Peak-Chew
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Aiwei Zeng
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Nina M Rzechorzek
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Nathan R James
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - James West
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Jack Munns
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - David Cs Wong
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Andrew D Beale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - John S O'Neill
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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4
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Chadani Y, Yamanouchi S, Uemura E, Yamasaki K, Niwa T, Ikeda T, Kurihara M, Iwasaki W, Taguchi H. The ABCF proteins in Escherichia coli individually cope with 'hard-to-translate' nascent peptide sequences. Nucleic Acids Res 2024; 52:5825-5840. [PMID: 38661232 PMCID: PMC11162784 DOI: 10.1093/nar/gkae309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 03/18/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024] Open
Abstract
Organisms possess a wide variety of proteins with diverse amino acid sequences, and their synthesis relies on the ribosome. Empirical observations have led to the misconception that ribosomes are robust protein factories, but in reality, they have several weaknesses. For instance, ribosomes stall during the translation of the proline-rich sequences, but the elongation factor EF-P assists in synthesizing proteins containing the poly-proline sequences. Thus, living organisms have evolved to expand the translation capability of ribosomes through the acquisition of translation elongation factors. In this study, we have revealed that Escherichia coli ATP-Binding Cassette family-F (ABCF) proteins, YheS, YbiT, EttA and Uup, individually cope with various problematic nascent peptide sequences within the exit tunnel. The correspondence between noncanonical translations and ABCFs was YheS for the translational arrest by nascent SecM, YbiT for poly-basic sequence-dependent stalling and poly-acidic sequence-dependent intrinsic ribosome destabilization (IRD), EttA for IRD at the early stage of elongation, and Uup for poly-proline-dependent stalling. Our results suggest that ATP hydrolysis-coupled structural rearrangement and the interdomain linker sequence are pivotal for handling 'hard-to-translate' nascent peptides. Our study highlights a new aspect of ABCF proteins to reduce the potential risks that are encoded within the nascent peptide sequences.
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Affiliation(s)
- Yuhei Chadani
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Shun Yamanouchi
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Eri Uemura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Kohei Yamasaki
- Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Tatsuya Niwa
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Toma Ikeda
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Miku Kurihara
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Wataru Iwasaki
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba 277-0882, Japan
| | - Hideki Taguchi
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan
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5
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Inada T, Beckmann R. Mechanisms of Translation-coupled Quality Control. J Mol Biol 2024; 436:168496. [PMID: 38365086 DOI: 10.1016/j.jmb.2024.168496] [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: 12/05/2023] [Revised: 02/05/2024] [Accepted: 02/12/2024] [Indexed: 02/18/2024]
Abstract
Stalling of ribosomes engaged in protein synthesis can lead to significant defects in the function of newly synthesized proteins and thereby impair protein homeostasis. Consequently, partially synthesized polypeptides resulting from translation stalling are recognized and eliminated by several quality control mechanisms. First, if translation elongation reactions are halted prematurely, a quality control mechanism called ribosome-associated quality control (RQC) initiates the ubiquitination of the nascent polypeptide chain and subsequent proteasomal degradation. Additionally, when ribosomes with defective codon recognition or peptide-bond formation stall during translation, a quality control mechanism known as non-functional ribosomal RNA decay (NRD) leads to the degradation of malfunctioning ribosomes. In both of these quality control mechanisms, E3 ubiquitin ligases selectively recognize ribosomes in distinct translation-stalling states and ubiquitinate specific ribosomal proteins. Significant efforts have been devoted to characterize E3 ubiquitin ligase sensing of ribosome 'collision' or 'stalling' and subsequent ribosome is rescued. This article provides an overview of our current understanding of the molecular mechanisms and physiological functions of ribosome dynamics control and quality control of abnormal translation.
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Affiliation(s)
- Toshifumi Inada
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-Ku, Tokyo 108-8639, Japan.
| | - Roland Beckmann
- Gene Center and Department of Biochemistry, Feodor-Lynen-Str. 25, University of Munich, 81377 Munich, Germany.
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6
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Tatara Y, Kasai S, Kokubu D, Tsujita T, Mimura J, Itoh K. Emerging Role of GCN1 in Disease and Homeostasis. Int J Mol Sci 2024; 25:2998. [PMID: 38474243 PMCID: PMC10931611 DOI: 10.3390/ijms25052998] [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: 01/29/2024] [Revised: 02/29/2024] [Accepted: 03/02/2024] [Indexed: 03/14/2024] Open
Abstract
GCN1 is recognized as a factor that is essential for the activation of GCN2, which is a sensor of amino acid starvation. This function is evolutionarily conserved from yeast to higher eukaryotes. However, recent studies have revealed non-canonical functions of GCN1 that are independent of GCN2, such as its participation in cell proliferation, apoptosis, and the immune response, beyond the borders of species. Although it is known that GCN1 and GCN2 interact with ribosomes to accomplish amino acid starvation sensing, recent studies have reported that GCN1 binds to disomes (i.e., ribosomes that collide each other), thereby regulating both the co-translational quality control and stress response. We propose that GCN1 regulates ribosome-mediated signaling by dynamically changing its partners among RWD domain-possessing proteins via unknown mechanisms. We recently demonstrated that GCN1 is essential for cell proliferation and whole-body energy regulation in mice. However, the manner in which ribosome-initiated signaling via GCN1 is related to various physiological functions warrants clarification. GCN1-mediated mechanisms and its interaction with other quality control and stress response signals should be important for proteostasis during aging and neurodegenerative diseases, and may be targeted for drug development.
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Affiliation(s)
- Yota Tatara
- Department of Stress Response Science, Biomedical Research Center, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Aomori, Japan
| | - Shuya Kasai
- Department of Stress Response Science, Biomedical Research Center, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Aomori, Japan
| | - Daichi Kokubu
- Diet and Well-Being Research Institute, KAGOME, Co., Ltd., 17 Nishitomiyama, Nasushiobara 329-2762, Tochigi, Japan
- Department of Vegetable Life Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Aomori, Japan
| | - Tadayuki Tsujita
- Laboratory of Biochemistry, Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga City 840-8502, Saga, Japan;
| | - Junsei Mimura
- Department of Stress Response Science, Biomedical Research Center, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Aomori, Japan
| | - Ken Itoh
- Department of Stress Response Science, Biomedical Research Center, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Aomori, Japan
- Department of Vegetable Life Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Aomori, Japan
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7
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Monem PC, Arribere JA. A ubiquitin language communicates ribosomal distress. Semin Cell Dev Biol 2024; 154:131-137. [PMID: 36963992 PMCID: PMC10878831 DOI: 10.1016/j.semcdb.2023.03.009] [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: 04/15/2022] [Revised: 02/10/2023] [Accepted: 03/16/2023] [Indexed: 03/26/2023]
Abstract
Cells entrust ribosomes with the critical task of identifying problematic mRNAs and facilitating their degradation. Ribosomes must communicate when they encounter and stall on an aberrant mRNA, lest they expose the cell to toxic and disease-causing proteins, or they jeopardize ribosome homeostasis and cellular translation. In recent years, ribosomal ubiquitination has emerged as a central signaling step in this process, and proteomic studies across labs and experimental systems show a myriad of ubiquitination sites throughout the ribosome. Work from many labs zeroed in on ubiquitination in one region of the small ribosomal subunit as being functionally significant, with the balance and exact ubiquitination sites determined by stall type, E3 ubiquitin ligases, and deubiquitinases. This review discusses the current literature surrounding ribosomal ubiquitination during translational stress and considers its role in committing translational complexes to decay.
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Affiliation(s)
- Parissa C Monem
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Joshua A Arribere
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA.
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8
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Collart MA, Audebert L, Bushell M. Roles of the CCR4-Not complex in translation and dynamics of co-translation events. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 15:e1827. [PMID: 38009591 PMCID: PMC10909573 DOI: 10.1002/wrna.1827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/06/2023] [Accepted: 10/30/2023] [Indexed: 11/29/2023]
Abstract
The Ccr4-Not complex is a global regulator of mRNA metabolism in eukaryotic cells that is most well-known to repress gene expression. Delivery of the complex to mRNAs through a multitude of distinct mechanisms accelerates their decay, yet Ccr4-Not also plays an important role in co-translational processes, such as co-translational association of proteins and delivery of translating mRNAs to organelles. The recent structure of Not5 interacting with the translated ribosome has brought to light that embedded information within the codon sequence can be monitored by recruitment of the Ccr4-Not complex to elongating ribosomes. Thereby, the Ccr4-Not complex is empowered with regulatory decisions determining the fate of proteins being synthesized and their encoding mRNAs. This review will focus on the roles of the complex in translation and dynamics of co-translation events. This article is categorized under: Translation > Mechanisms Translation > Regulation.
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Affiliation(s)
- Martine A. Collart
- Department of Microbiology and Molecular MedicineInstitute of Genetics and Genomics Geneva, University of Geneva, Faculty of MedicineGenèveSwitzerland
| | - Léna Audebert
- Department of Microbiology and Molecular MedicineInstitute of Genetics and Genomics Geneva, University of Geneva, Faculty of MedicineGenèveSwitzerland
| | - Martin Bushell
- Cancer Research UK Beatson InstituteGlasgowUK
- School of Cancer Sciences, University of GlasgowGlasgowUK
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9
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Alagar Boopathy LR, Beadle E, Garcia-Bueno Rico A, Vera M. Proteostasis regulation through ribosome quality control and no-go-decay. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1809. [PMID: 37488089 DOI: 10.1002/wrna.1809] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 06/14/2023] [Accepted: 06/30/2023] [Indexed: 07/26/2023]
Abstract
Cell functionality relies on the existing pool of proteins and their folding into functional conformations. This is achieved through the regulation of protein synthesis, which requires error-free mRNAs and ribosomes. Ribosomes are quality control hubs for mRNAs and proteins. Problems during translation elongation slow down the decoding rate, leading to ribosome halting and the eventual collision with the next ribosome. Collided ribosomes form a specific disome structure recognized and solved by ribosome quality control (RQC) mechanisms. RQC pathways orchestrate the degradation of the problematic mRNA by no-go decay and the truncated nascent peptide, the repression of translation initiation, and the recycling of the stalled ribosomes. All these events maintain protein homeostasis and return valuable ribosomes to translation. As such, cell homeostasis and function are maintained at the mRNA level by preventing the production of aberrant or unnecessary proteins. It is becoming evident that the crosstalk between RQC and the protein homeostasis network is vital for cell function, as the absence of RQC components leads to the activation of stress response and neurodegenerative diseases. Here, we review the molecular events of RQC discovered through well-designed stalling reporters. Given the impact of RQC in proteostasis, we discuss the relevance of identifying endogenous mRNA regulated by RQC and their preservation in stress conditions. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms Translation > Regulation.
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Affiliation(s)
| | - Emma Beadle
- Department of Biochemistry, McGill University, Montreal, Canada
| | | | - Maria Vera
- Department of Biochemistry, McGill University, Montreal, Canada
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10
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Chen KY, Park H, Subramaniam AR. Massively parallel identification of sequence motifs triggering ribosome-associated mRNA quality control. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.27.559793. [PMID: 37808677 PMCID: PMC10557687 DOI: 10.1101/2023.09.27.559793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Decay of mRNAs can be triggered by ribosome slowdown at stretches of rare codons or positively charged amino acids. However, the full diversity of sequences that trigger co-translational mRNA decay is poorly understood. To comprehensively identify sequence motifs that trigger mRNA decay, we use a massively parallel reporter assay to measure the effect of all possible combinations of codon pairs on mRNA levels in S. cerevisiae. In addition to known mRNA-destabilizing sequences, we identify several dipeptide repeats whose translation reduces mRNA levels. These include combinations of positively charged and bulky residues, as well as proline-glycine and proline-aspartate dipeptide repeats. Genetic deletion of the ribosome collision sensor Hel2 rescues the mRNA effects of these motifs, suggesting that they trigger ribosome slowdown and activate the ribosome-associated quality control (RQC) pathway. Deep mutational scanning of an mRNA-destabilizing dipeptide repeat reveals a complex interplay between the charge, bulkiness, and location of amino acid residues in conferring mRNA instability. Finally, we show that the mRNA effects of codon pairs are predictive of the effects of endogenous sequences. Our work highlights the complexity of sequence motifs driving co-translational mRNA decay in eukaryotes, and presents a high throughput approach to dissect their requirements at the codon level.
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Affiliation(s)
- Katharine Y. Chen
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Heungwon Park
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Arvind Rasi Subramaniam
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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11
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Alagar Boopathy L, Beadle E, Xiao A, Garcia-Bueno Rico A, Alecki C, Garcia de-Andres I, Edelmeier K, Lazzari L, Amiri M, Vera M. The ribosome quality control factor Asc1 determines the fate of HSP70 mRNA on and off the ribosome. Nucleic Acids Res 2023; 51:6370-6388. [PMID: 37158240 PMCID: PMC10325905 DOI: 10.1093/nar/gkad338] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 04/16/2023] [Accepted: 04/20/2023] [Indexed: 05/10/2023] Open
Abstract
Cells survive harsh environmental conditions by potently upregulating molecular chaperones such as heat shock proteins (HSPs), particularly the inducible members of the HSP70 family. The life cycle of HSP70 mRNA in the cytoplasm is unique-it is translated during stress when most cellular mRNA translation is repressed and rapidly degraded upon recovery. Contrary to its 5' untranslated region's role in maximizing translation, we discovered that the HSP70 coding sequence (CDS) suppresses its translation via the ribosome quality control (RQC) mechanism. The CDS of the most inducible Saccharomyces cerevisiae HSP70 gene, SSA4, is uniquely enriched with low-frequency codons that promote ribosome stalling during heat stress. Stalled ribosomes are recognized by the RQC components Asc1p and Hel2p and two novel RQC components, the ribosomal proteins Rps28Ap and Rps19Bp. Surprisingly, RQC does not signal SSA4 mRNA degradation via No-Go-Decay. Instead, Asc1p destabilizes SSA4 mRNA during recovery from heat stress by a mechanism independent of ribosome binding and SSA4 codon optimality. Therefore, Asc1p operates in two pathways that converge to regulate the SSA4 mRNA life cycle during stress and recovery. Our research identifies Asc1p as a critical regulator of the stress response and RQC as the mechanism tuning HSP70 synthesis.
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Affiliation(s)
| | - Emma Beadle
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
| | - Alan RuoChen Xiao
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
| | | | - Celia Alecki
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
| | | | - Kyla Edelmeier
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
| | - Luca Lazzari
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
| | - Mehdi Amiri
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
| | - Maria Vera
- Department of Biochemistry. McGill University, Montreal, QuebecH3G 1Y6, Canada
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12
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Nakajima M, Koido M, Guo L, Terao C, Ikegawa S. A novel CCDC91 isoform associated with ossification of the posterior longitudinal ligament of the spine works as a non-coding RNA to regulate osteogenic genes. Am J Hum Genet 2023; 110:638-647. [PMID: 36990086 PMCID: PMC10119134 DOI: 10.1016/j.ajhg.2023.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/07/2023] [Indexed: 03/30/2023] Open
Abstract
Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common intractable disease that causes spinal stenosis and myelopathy. We have previously conducted genome-wide association studies for OPLL and identified 14 significant loci, but their biological implications remain mostly unclear. Here, we examined the 12p11.22 locus and identified a variant in the 5' UTR of a novel isoform of CCDC91 that was associated with OPLL. Using machine learning prediction models, we determined that higher expression of the novel CCDC91 isoform was associated with the G allele of rs35098487. The risk allele of rs35098487 showed higher affinity in the binding of nuclear proteins and transcription activity. Knockdown and overexpression of the CCDC91 isoform in mesenchymal stem cells and MG-63 cells showed paralleled expression of osteogenic genes, including RUNX2, the master transcription factor of osteogenic differentiation. The CCDC91 isoform directly interacted with MIR890, which bound to RUNX2 and decreased RUNX2 expression. Our findings suggest that the CCDC91 isoform acts as a competitive endogenous RNA by sponging MIR890 to increase RUNX2 expression.
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Affiliation(s)
- Masahiro Nakajima
- Laboratory for Bone and Joint Diseases, Center for Integrative Medical Sciences, RIKEN, Tokyo 108-8639, Japan
| | - Masaru Koido
- Laboratory for Statistical and Translational Genetics, Center for Integrative Medical Sciences, RIKEN, Yokohama 230-0045, Japan; Laboratory of Complex Trait Genomics, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 108-8639, Japan
| | - Long Guo
- Laboratory for Bone and Joint Diseases, Center for Integrative Medical Sciences, RIKEN, Tokyo 108-8639, Japan; Department of Laboratory Animal Science, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an 710061, China
| | - Chikashi Terao
- Laboratory for Statistical and Translational Genetics, Center for Integrative Medical Sciences, RIKEN, Yokohama 230-0045, Japan.
| | - Shiro Ikegawa
- Laboratory for Bone and Joint Diseases, Center for Integrative Medical Sciences, RIKEN, Tokyo 108-8639, Japan.
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13
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Not1 and Not4 inversely determine mRNA solubility that sets the dynamics of co-translational events. Genome Biol 2023; 24:30. [PMID: 36803582 PMCID: PMC9940351 DOI: 10.1186/s13059-023-02871-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 02/10/2023] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND The Ccr4-Not complex is mostly known as the major eukaryotic deadenylase. However, several studies have uncovered roles of the complex, in particular of the Not subunits, unrelated to deadenylation and relevant for translation. In particular, the existence of Not condensates that regulate translation elongation dynamics has been reported. Typical studies that evaluate translation efficiency rely on soluble extracts obtained after the disruption of cells and ribosome profiling. Yet cellular mRNAs in condensates can be actively translated and may not be present in such extracts. RESULTS In this work, by analyzing soluble and insoluble mRNA decay intermediates in yeast, we determine that insoluble mRNAs are enriched for ribosomes dwelling at non-optimal codons compared to soluble mRNAs. mRNA decay is higher for soluble RNAs, but the proportion of co-translational degradation relative to the overall mRNA decay is higher for insoluble mRNAs. We show that depletion of Not1 and Not4 inversely impacts mRNA solubilities and, for soluble mRNAs, ribosome dwelling according to codon optimality. Depletion of Not4 solubilizes mRNAs with lower non-optimal codon content and higher expression that are rendered insoluble by Not1 depletion. By contrast, depletion of Not1 solubilizes mitochondrial mRNAs, which are rendered insoluble upon Not4 depletion. CONCLUSIONS Our results reveal that mRNA solubility defines the dynamics of co-translation events and is oppositely regulated by Not1 and Not4, a mechanism that we additionally determine may already be set by Not1 promoter association in the nucleus.
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14
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Matsuo Y, Inada T. Co-Translational Quality Control Induced by Translational Arrest. Biomolecules 2023; 13:biom13020317. [PMID: 36830686 PMCID: PMC9953336 DOI: 10.3390/biom13020317] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/19/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023] Open
Abstract
Genetic mutations, mRNA processing errors, and lack of availability of charged tRNAs sometimes slow down or completely stall translating ribosomes. Since an incomplete nascent chain derived from stalled ribosomes may function anomalously, such as by forming toxic aggregates, surveillance systems monitor every step of translation and dispose of such products to prevent their accumulation. Over the past decade, yeast models with powerful genetics and biochemical techniques have contributed to uncovering the mechanism of the co-translational quality control system, which eliminates the harmful products generated from aberrant translation. We here summarize the current knowledge of the molecular mechanism of the co-translational quality control systems in yeast, which eliminate the incomplete nascent chain, improper mRNAs, and faulty ribosomes to maintain cellular protein homeostasis.
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15
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Tomomatsu S, Watanabe A, Tesina P, Hashimoto S, Ikeuchi K, Li S, Matsuo Y, Beckmann R, Inada T. Two modes of Cue2-mediated mRNA cleavage with distinct substrate recognition initiate no-go decay. Nucleic Acids Res 2022; 51:253-270. [PMID: 36583309 PMCID: PMC9841427 DOI: 10.1093/nar/gkac1172] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/17/2022] [Accepted: 11/25/2022] [Indexed: 12/31/2022] Open
Abstract
Ribosome collisions are recognized by E3 ubiquitin ligase Hel2/ZNF598, leading to RQC (ribosome-associated quality control) and to endonucleolytic cleavage and degradation of the mRNA termed NGD (no-go decay). NGD in yeast requires the Cue2 endonuclease and occurs in two modes, either coupled to RQC (NGDRQC+) or RQC uncoupled (NGDRQC-). This is mediated by an unknown mechanism of substrate recognition by Cue2. Here, we show that the ubiquitin binding activity of Cue2 is required for NGDRQC- but not for NGDRQC+, and that it involves the first two N-terminal Cue domains. In contrast, Trp122 of Cue2 is crucial for NGDRQC+. Moreover, Mbf1 is required for quality controls by preventing +1 ribosome frameshifting induced by a rare codon staller. We propose that in Cue2-dependent cleavage upstream of the collided ribosomes (NGDRQC-), polyubiquitination of eS7 is recognized by two N-terminal Cue domains of Cue2. In contrast, for the cleavage within collided ribosomes (NGDRQC+), the UBA domain, Trp122 and the interaction between Mbf1 and uS3 are critical.
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Affiliation(s)
| | | | - Petr Tesina
- Gene Center and Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, D-81377 Munich, Germany
| | - Satoshi Hashimoto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Ken Ikeuchi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan,Gene Center and Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, D-81377 Munich, Germany
| | - Sihan Li
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-Ku 108-8639, Japan,Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Yoshitaka Matsuo
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-Ku 108-8639, Japan,Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Roland Beckmann
- Gene Center and Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, D-81377 Munich, Germany
| | - Toshifumi Inada
- To whom correspondence should be addressed. Tel: +81 3 5449 5275; Fax: +81 3 5449 5275;
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16
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The human CNOT1-CNOT10-CNOT11 complex forms a structural platform for protein-protein interactions. Cell Rep 2022; 42:111902. [PMID: 36586408 PMCID: PMC9902336 DOI: 10.1016/j.celrep.2022.111902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 10/27/2022] [Accepted: 12/08/2022] [Indexed: 12/31/2022] Open
Abstract
The evolutionary conserved CCR4-NOT complex functions in the cytoplasm as the main mRNA deadenylase in both constitutive mRNA turnover and regulated mRNA decay pathways. The versatility of this complex is underpinned by its modular multi-subunit organization, with distinct structural modules actuating different functions. The structure and function of all modules are known, except for that of the N-terminal module. Using different structural approaches, we obtained high-resolution data revealing the architecture of the human N-terminal module composed of CNOT1, CNOT10, and CNOT11. The structure shows how two helical domains of CNOT1 sandwich CNOT10 and CNOT11, leaving the most conserved domain of CNOT11 protruding into solvent as an antenna. We discovered that GGNBP2, a protein identified as a tumor suppressor and spermatogenic factor, is a conserved interacting partner of the CNOT11 antenna domain. Structural and biochemical analyses thus pinpoint the N-terminal CNOT1-CNOT10-CNOT11 module as a conserved protein-protein interaction platform.
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17
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Ito Y, Chadani Y, Niwa T, Yamakawa A, Machida K, Imataka H, Taguchi H. Nascent peptide-induced translation discontinuation in eukaryotes impacts biased amino acid usage in proteomes. Nat Commun 2022; 13:7451. [PMID: 36460666 PMCID: PMC9718836 DOI: 10.1038/s41467-022-35156-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 11/18/2022] [Indexed: 12/04/2022] Open
Abstract
Robust translation elongation of any given amino acid sequence is required to shape proteomes. Nevertheless, nascent peptides occasionally destabilize ribosomes, since consecutive negatively charged residues in bacterial nascent chains can stochastically induce discontinuation of translation, in a phenomenon termed intrinsic ribosome destabilization (IRD). Here, using budding yeast and a human factor-based reconstituted translation system, we show that IRD also occurs in eukaryotic translation. Nascent chains enriched in aspartic acid (D) or glutamic acid (E) in their N-terminal regions alter canonical ribosome dynamics, stochastically aborting translation. Although eukaryotic ribosomes are more robust to ensure uninterrupted translation, we find many endogenous D/E-rich peptidyl-tRNAs in the N-terminal regions in cells lacking a peptidyl-tRNA hydrolase, indicating that the translation of the N-terminal D/E-rich sequences poses an inherent risk of failure. Indeed, a bioinformatics analysis reveals that the N-terminal regions of ORFs lack D/E enrichment, implying that the translation defect partly restricts the overall amino acid usage in proteomes.
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Affiliation(s)
- Yosuke Ito
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
| | - Yuhei Chadani
- grid.32197.3e0000 0001 2179 2105Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
| | - Tatsuya Niwa
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8503 Japan ,grid.32197.3e0000 0001 2179 2105Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
| | - Ayako Yamakawa
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
| | - Kodai Machida
- grid.266453.00000 0001 0724 9317Graduate School of Engineering, University of Hyogo, Himeji, Hyogo 671-2280 Japan
| | - Hiroaki Imataka
- grid.266453.00000 0001 0724 9317Graduate School of Engineering, University of Hyogo, Himeji, Hyogo 671-2280 Japan
| | - Hideki Taguchi
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8503 Japan ,grid.32197.3e0000 0001 2179 2105Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
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18
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Dhaliwal JS, Panozzo C, Benard L, Zerges W. An RNA granule for translation quality control in Saccharomyces cerevisiae. J Cell Sci 2022; 135:285862. [PMID: 36373798 DOI: 10.1242/jcs.260388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 10/31/2022] [Indexed: 11/16/2022] Open
Abstract
Cytoplasmic RNA granules compartmentalize phases of the translation cycle in eukaryotes. We previously reported the localization of oxidized RNA to cytoplasmic foci called oxidized RNA bodies (ORBs) in human cells. We show here that ORBs are RNA granules in Saccharomyces cerevisiae. Several lines of evidence support a role for ORBs in the compartmentalization of no-go decay and ribosome quality control, the translation quality control pathways that recognize and clear aberrant mRNAs, including those with oxidized bases. Translation is required by these pathways and ORBs. Translation quality control factors localize to ORBs. A substrate of translation quality control, a stalled mRNA-ribosome-nascent-chain complex, localizes to ORBs. Translation quality control mutants have altered ORB numbers, sizes or both. In addition, we identify 68 ORB proteins by immunofluorescence staining directed by proteomics, which further support their role in translation quality control and reveal candidate new factors for these pathways.
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Affiliation(s)
- James S Dhaliwal
- Department of Biology, Concordia University, 7141 Sherbrooke W, Montreal, Quebec, Canada, H4B 1R6
| | - Cristina Panozzo
- Institut de Biologie Physico-Chimique, UMR8226, CNRS, Sorbonne Université, 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Lionel Benard
- Institut de Biologie Physico-Chimique, UMR8226, CNRS, Sorbonne Université, 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - William Zerges
- Department of Biology, Concordia University, 7141 Sherbrooke W, Montreal, Quebec, Canada, H4B 1R6
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19
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Okuda H, Miyamoto R, Takahashi S, Kawamura T, Ichikawa J, Harada I, Tamura T, Yokoyama A. RNA-binding proteins of KHDRBS and IGF2BP families control the oncogenic activity of MLL-AF4. Nat Commun 2022; 13:6688. [PMID: 36335100 PMCID: PMC9637093 DOI: 10.1038/s41467-022-34558-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 10/27/2022] [Indexed: 11/08/2022] Open
Abstract
Chromosomal translocation generates the MLL-AF4 fusion gene, which causes acute leukemia of multiple lineages. MLL-AF4 is a strong oncogenic driver that induces leukemia without additional mutations and is the most common cause of pediatric leukemia. However, establishment of a murine disease model via retroviral transduction has been difficult owning to a lack of understanding of its regulatory mechanisms. Here, we show that MLL-AF4 protein is post-transcriptionally regulated by RNA-binding proteins, including those of KHDRBS and IGF2BP families. MLL-AF4 translation is inhibited by ribosomal stalling, which occurs at regulatory sites containing AU-rich sequences recognized by KHDRBSs. Synonymous mutations disrupting the association of KHDRBSs result in proper translation of MLL-AF4 and leukemic transformation. Consequently, the synonymous MLL-AF4 mutant induces leukemia in vivo. Our results reveal that post-transcriptional regulation critically controls the oncogenic activity of MLL-AF4; these findings might be valuable in developing novel therapies via modulation of the activity of RNA-binding proteins.
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Affiliation(s)
- Hiroshi Okuda
- grid.272242.30000 0001 2168 5385Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Yamagata Japan ,grid.268441.d0000 0001 1033 6139Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa Japan
| | - Ryo Miyamoto
- grid.272242.30000 0001 2168 5385Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Yamagata Japan
| | - Satoshi Takahashi
- grid.272242.30000 0001 2168 5385Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Yamagata Japan ,grid.258799.80000 0004 0372 2033Department of Hematology and Oncology, Kyoto University Graduate School of Medicine, Kyoto, Kyoto Japan
| | - Takeshi Kawamura
- grid.26999.3d0000 0001 2151 536XResearch Center for Advanced Science and Technology (RCAST), The University of Tokyo, Bunkyo, Tokyo Japan
| | - Juri Ichikawa
- grid.268441.d0000 0001 1033 6139Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa Japan
| | - Ibuki Harada
- grid.268441.d0000 0001 1033 6139Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa Japan
| | - Tomohiko Tamura
- grid.268441.d0000 0001 1033 6139Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa Japan ,grid.268441.d0000 0001 1033 6139Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa Japan
| | - Akihiko Yokoyama
- grid.272242.30000 0001 2168 5385Tsuruoka Metabolomics Laboratory, National Cancer Center, Tsuruoka, Yamagata Japan ,grid.272242.30000 0001 2168 5385National Cancer Center Research Institute, Chuo, Tokyo Japan
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20
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Bottorff TA, Park H, Geballe AP, Subramaniam AR. Translational buffering by ribosome stalling in upstream open reading frames. PLoS Genet 2022; 18:e1010460. [PMID: 36315596 PMCID: PMC9648851 DOI: 10.1371/journal.pgen.1010460] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/10/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022] Open
Abstract
Upstream open reading frames (uORFs) are present in over half of all human mRNAs. uORFs can potently regulate the translation of downstream open reading frames through several mechanisms: siphoning away scanning ribosomes, regulating re-initiation, and allowing interactions between scanning and elongating ribosomes. However, the consequences of these different mechanisms for the regulation of protein expression remain incompletely understood. Here, we performed systematic measurements on the uORF-containing 5' UTR of the cytomegaloviral UL4 mRNA to test alternative models of uORF-mediated regulation in human cells. We find that a terminal diproline-dependent elongating ribosome stall in the UL4 uORF prevents decreases in main ORF protein expression when ribosome loading onto the mRNA is reduced. This uORF-mediated buffering is insensitive to the location of the ribosome stall along the uORF. Computational kinetic modeling based on our measurements suggests that scanning ribosomes dissociate rather than queue when they collide with stalled elongating ribosomes within the UL4 uORF. We identify several human uORFs that repress main ORF protein expression via a similar terminal diproline motif. We propose that ribosome stalls in uORFs provide a general mechanism for buffering against reductions in main ORF translation during stress and developmental transitions.
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Affiliation(s)
- Ty A. Bottorff
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, Washington, United States of America
| | - Heungwon Park
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Adam P. Geballe
- Human Biology and Clinical Research Divisions, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Arvind Rasi Subramaniam
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, Washington, United States of America
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21
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Ho AT, Hurst LD. Stop codon usage as a window into genome evolution: mutation, selection, biased gene conversion and the TAG paradox. Genome Biol Evol 2022; 14:6648529. [PMID: 35867377 PMCID: PMC9348620 DOI: 10.1093/gbe/evac115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2022] [Indexed: 11/16/2022] Open
Abstract
Protein coding genes terminate with one of three stop codons (TAA, TGA, or TAG) that, like synonymous codons, are not employed equally. With TGA and TAG having identical nucleotide content, analysis of their differential usage provides an unusual window into the forces operating on what are ostensibly functionally identical residues. Across genomes and between isochores within the human genome, TGA usage increases with G + C content but, with a common G + C → A + T mutation bias, this cannot be explained by mutation bias-drift equilibrium. Increased usage of TGA in G + C-rich genomes or genomic regions is also unlikely to reflect selection for the optimal stop codon, as TAA appears to be universally optimal, probably because it has the lowest read-through rate. Despite TAA being favored by selection and mutation bias, as with codon usage bias G + C pressure is the prime determinant of between-species TGA usage trends. In species with strong G + C-biased gene conversion (gBGC), such as mammals and birds, the high usage and conservation of TGA is best explained by an A + T → G + C repair bias. How to explain TGA enrichment in other G + C-rich genomes is less clear. Enigmatically, across bacterial and archaeal species and between human isochores TAG usage is mostly unresponsive to G + C pressure. This unresponsiveness we dub the TAG paradox as currently no mutational, selective, or gBGC model provides a well-supported explanation. That TAG does increase with G + C usage across eukaryotes makes the usage elsewhere yet more enigmatic. We suggest resolution of the TAG paradox may provide insights into either an unknown but common selective preference (probably at the DNA/RNA level) or an unrecognized complexity to the action of gBGC.
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Affiliation(s)
- Alexander T Ho
- Milner Centre for Evolution, University of Bath, Bath, UK
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22
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Shimohata N, Harada Y, Hayano T. Proteomic analysis of nascent polypeptide chains that potentially induce translational pausing during elongation. Biosci Biotechnol Biochem 2022; 86:1262-1269. [PMID: 35749475 DOI: 10.1093/bbb/zbac097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022]
Abstract
Currently, proteins equipped with "ribosomal arrest peptides" (RAPs) that regulate the expression of downstream genes and their own activity by pausing their own translation during elongation are extensively studied. However, studies focusing on RAP have been conducted primarily in prokaryotic cells; studies on eukaryotic cells, especially mammalian cells, are limited. In the present study, we comprehensively examined translationally arrested nascent polypeptides to gain novel insights into RAPs in mammalian cells. Cetyltrimethylammonium bromide was used to obtain nascent polypeptide chains that were translationally arrested during translation elongation. After proteomic analysis, additional screening by discriminating according to amino acid residues at the C-terminal end revealed several novel RAP candidates. Our method can be applied for comprehensive RAP studies in mammalian cells.
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Affiliation(s)
- Nobuyuki Shimohata
- Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan.,Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan
| | - Yudai Harada
- Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan
| | - Toshiya Hayano
- Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan
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23
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mRNA and tRNA modification states influence ribosome speed and frame maintenance during poly(lysine) peptide synthesis. J Biol Chem 2022; 298:102039. [PMID: 35595100 PMCID: PMC9207662 DOI: 10.1016/j.jbc.2022.102039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 12/16/2022] Open
Abstract
Ribosome speed is dictated by multiple factors including substrate availability, cellular conditions, and product (peptide) formation. Translation slows during the synthesis of cationic peptide sequences, potentially influencing the expression of thousands of proteins. Available evidence suggests that ionic interactions between positively charged nascent peptides and the negatively charged ribosome exit tunnel impede translation. However, this hypothesis was difficult to test directly because of inability to decouple the contributions of amino acid charge from mRNA sequence and tRNA identity/abundance in cells. Furthermore, it is unclear if other components of the translation system central to ribosome function (e.g., RNA modification) influence the speed and accuracy of positively charged peptide synthesis. In this study, we used a fully reconstituted Escherichia coli translation system to evaluate the effects of peptide charge, mRNA sequence, and RNA modification status on the translation of lysine-rich peptides. Comparison of translation reactions on poly(lysine)-encoding mRNAs conducted with either Lys-tRNALys or Val-tRNALys reveals that that amino acid charge, while important, only partially accounts for slowed translation on these transcripts. We further find that in addition to peptide charge, mRNA sequence and both tRNA and mRNA modification status influence the rates of amino acid addition and the ribosome’s ability to maintain frame (instead of entering the −2, −1, and +1 frames) during poly(lysine) peptide synthesis. Our observations lead us to expand the model for explaining how the ribosome slows during poly(lysine) peptide synthesis and suggest that posttranscriptional RNA modifications can provide cells a mechanism to precisely control ribosome movements along an mRNA.
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24
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Hogrel G, Marino-Puertas L, Laurent S, Ibrahim Z, Covès J, Girard E, Gabel F, Fenel D, Daugeron MC, Clouet-d'Orval B, Basta T, Flament D, Franzetti B. Characterization of a small tRNA-binding protein that interacts with the archaeal proteasome complex. Mol Microbiol 2022; 118:16-29. [PMID: 35615908 PMCID: PMC9540759 DOI: 10.1111/mmi.14948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 11/27/2022]
Abstract
The proteasome system allows the elimination of functional or structurally impaired proteins. This includes the degradation of nascent peptides. In Archaea, how the proteasome complex interacts with the translational machinery remains to be described. Here, we characterised a small orphan protein, Q9UZY3 (Uniprot ID) conserved in Thermococcales. The protein was identified in native pull-down experiments using the proteasome regulatory complex (PAN) as bait. X-ray crystallography and SAXS experiments revealed that the protein is monomeric and adopts a β-barrel core structure with an Oligonucleotide/oligosaccharide-Binding (OB) fold, typically found in translation elongation factors. Mobility shift experiment showed that Q9UZY3 displays tRNA binding properties. Pull-downs, co-immunoprecipitation and ITC studies revealed that Q9UZY3 interacts in vitro with PAN. Native pull-downs and proteomic analysis using different versions of Q9UZY3 showed that the protein interacts with the assembled PAN-20S proteasome machinery in Pyrococcus abyssi cellular extracts. The protein was therefore named Pbp11, for Proteasome Binding Protein of 11 kDa. Interestingly, the interaction network of Pbp11 also includes ribosomal proteins, tRNA processing enzymes and exosome subunits dependent on Pbp11's N-terminal domain that was found to be essential for tRNA binding. Together these data suggest that Pbp11 participates in an interface between the proteasome and the translational machinery.
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Affiliation(s)
- Gaëlle Hogrel
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France.,University of St Andrews, St Andrews, UK
| | | | - Sébastien Laurent
- Univ Brest, Ifremer, CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, Plouzané, France
| | - Ziad Ibrahim
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France.,University of Leicester, Leicester, UK
| | - Jacques Covès
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Eric Girard
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Frank Gabel
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Daphna Fenel
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Marie-Claire Daugeron
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Béatrice Clouet-d'Orval
- Laboratoire de Microbiologie et de Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Tamara Basta
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Didier Flament
- Univ Brest, Ifremer, CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, Plouzané, France
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25
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Ho AT, Hurst LD. Unusual mammalian usage of TGA stop codons reveals that sequence conservation need not imply purifying selection. PLoS Biol 2022; 20:e3001588. [PMID: 35550630 PMCID: PMC9129041 DOI: 10.1371/journal.pbio.3001588] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/24/2022] [Accepted: 04/20/2022] [Indexed: 11/18/2022] Open
Abstract
The assumption that conservation of sequence implies the action of purifying selection is central to diverse methodologies to infer functional importance. GC-biased gene conversion (gBGC), a meiotic mismatch repair bias strongly favouring GC over AT, can in principle mimic the action of selection, this being thought to be especially important in mammals. As mutation is GC→AT biased, to demonstrate that gBGC does indeed cause false signals requires evidence that an AT-rich residue is selectively optimal compared to its more GC-rich allele, while showing also that the GC-rich alternative is conserved. We propose that mammalian stop codon evolution provides a robust test case. Although in most taxa TAA is the optimal stop codon, TGA is both abundant and conserved in mammalian genomes. We show that this mammalian exceptionalism is well explained by gBGC mimicking purifying selection and that TAA is the selectively optimal codon. Supportive of gBGC, we observe (i) TGA usage trends are consistent at the focal stop codon and elsewhere (in UTR sequences); (ii) that higher TGA usage and higher TAA→TGA substitution rates are predicted by a high recombination rate; and (iii) across species the difference in TAA <-> TGA substitution rates between GC-rich and GC-poor genes is largest in genomes that possess higher between-gene GC variation. TAA optimality is supported both by enrichment in highly expressed genes and trends associated with effective population size. High TGA usage and high TAA→TGA rates in mammals are thus consistent with gBGC’s predicted ability to “drive” deleterious mutations and supports the hypothesis that sequence conservation need not be indicative of purifying selection. A general trend for GC-rich trinucleotides to reside at frequencies far above their mutational equilibrium in high recombining domains supports the generality of these results.
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Affiliation(s)
- Alexander Thomas Ho
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
- * E-mail:
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26
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Houston L, Platten EM, Connelly SM, Wang J, Grayhack EJ. Frameshifting at collided ribosomes is modulated by elongation factor eEF3 and by integrated stress response regulators Gcn1 and Gcn20. RNA (NEW YORK, N.Y.) 2022; 28:320-339. [PMID: 34916334 PMCID: PMC8848926 DOI: 10.1261/rna.078964.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/25/2021] [Indexed: 06/14/2023]
Abstract
Ribosome stalls can result in ribosome collisions that elicit quality control responses, one function of which is to prevent ribosome frameshifting, an activity that entails the interaction of the conserved yeast protein Mbf1 with uS3 on colliding ribosomes. However, the full spectrum of factors that mediate frameshifting during ribosome collisions is unknown. To delineate such factors in the yeast Saccharomyces cerevisiae, we used genetic selections for mutants that affect frameshifting from a known ribosome stall site, CGA codon repeats. We show that the general translation elongation factor eEF3 and the integrated stress response (ISR) pathway components Gcn1 and Gcn20 modulate frameshifting in opposing manners. We found a mutant form of eEF3 that specifically suppressed frameshifting, but not translation inhibition by CGA codons. Thus, we infer that frameshifting at collided ribosomes requires eEF3, which facilitates tRNA-mRNA translocation and E-site tRNA release in yeast and other single cell organisms. In contrast, we found that removal of either Gcn1 or Gcn20, which bind collided ribosomes with Mbf1, increased frameshifting. Thus, we conclude that frameshifting is suppressed by Gcn1 and Gcn20, although these effects are not mediated primarily through activation of the ISR. Furthermore, we examined the relationship between eEF3-mediated frameshifting and other quality control mechanisms, finding that Mbf1 requires either Hel2 or Gcn1 to suppress frameshifting with wild-type eEF3. Thus, these results provide evidence of a direct link between translation elongation and frameshifting at collided ribosomes, as well as evidence that frameshifting is constrained by quality control mechanisms that act on collided ribosomes.
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Affiliation(s)
- Lisa Houston
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| | - Evan M Platten
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| | - Sara M Connelly
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| | - Jiyu Wang
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| | - Elizabeth J Grayhack
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
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27
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Mishima Y, Han P, Ishibashi K, Kimura S, Iwasaki S. Ribosome slowdown triggers codon-mediated mRNA decay independently of ribosome quality control. EMBO J 2022; 41:e109256. [PMID: 35040509 PMCID: PMC8886528 DOI: 10.15252/embj.2021109256] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 12/11/2022] Open
Abstract
The control of mRNA stability plays a central role in regulating gene expression patterns. Recent studies have revealed that codon composition in the open reading frame determines mRNA stability in multiple organisms. Based on genome-wide correlation approaches, this previously unrecognized role for the genetic code is attributable to the kinetics of the codon-decoding process by the ribosome. However, complementary experimental analyses are required to clarify the codon effects on mRNA stability and the related cotranslational mRNA decay pathways, for example, those triggered by aberrant ribosome stalling. In the current study, we performed a set of reporter-based analyses to define codon-mediated mRNA decay and ribosome stall-dependent mRNA decay in zebrafish embryos. Our analysis showed that the effect of codons on mRNA stability stems from the decoding process, independent of the ribosome quality control factor Znf598 and stalling-dependent mRNA decay. We propose that codon-mediated mRNA decay is rather triggered by transiently slowed ribosomes engaging in a productive translation cycle in zebrafish embryos.
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Affiliation(s)
- Yuichiro Mishima
- Department of Frontier Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan,RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan
| | - Peixun Han
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan,Department of Computational Biology and Medical SciencesGraduate School of Frontier SciencesThe University of TokyoChibaJapan
| | - Kota Ishibashi
- Department of Frontier Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan
| | - Seisuke Kimura
- Department of Industrial Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan,Center for Plant SciencesKyoto Sangyo UniversityKyotoJapan
| | - Shintaro Iwasaki
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan,Department of Computational Biology and Medical SciencesGraduate School of Frontier SciencesThe University of TokyoChibaJapan
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28
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Stein KC, Morales-Polanco F, van der Lienden J, Rainbolt TK, Frydman J. Ageing exacerbates ribosome pausing to disrupt cotranslational proteostasis. Nature 2022; 601:637-642. [PMID: 35046576 DOI: 10.1038/s41586-021-04295-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 12/01/2021] [Indexed: 02/04/2023]
Abstract
Ageing is accompanied by a decline in cellular proteostasis, which underlies many age-related protein misfolding diseases1,2. Yet, how ageing impairs proteostasis remains unclear. As nascent polypeptides represent a substantial burden on the proteostasis network3, we hypothesized that altered translational efficiency during ageing could help to drive the collapse of proteostasis. Here we show that ageing alters the kinetics of translation elongation in both Caenorhabditis elegans and Saccharomyces cerevisiae. Ribosome pausing was exacerbated at specific positions in aged yeast and worms, including polybasic stretches, leading to increased ribosome collisions known to trigger ribosome-associated quality control (RQC)4-6. Notably, aged yeast cells exhibited impaired clearance and increased aggregation of RQC substrates, indicating that ageing overwhelms this pathway. Indeed, long-lived yeast mutants reduced age-dependent ribosome pausing, and extended lifespan correlated with greater flux through the RQC pathway. Further linking altered translation to proteostasis collapse, we found that nascent polypeptides exhibiting age-dependent ribosome pausing in C. elegans were strongly enriched among age-dependent protein aggregates. Notably, ageing increased the pausing and aggregation of many components of proteostasis, which could initiate a cycle of proteostasis collapse. We propose that increased ribosome pausing, leading to RQC overload and nascent polypeptide aggregation, critically contributes to proteostasis impairment and systemic decline during ageing.
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Affiliation(s)
- Kevin C Stein
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | | | | | - Judith Frydman
- Department of Biology, Stanford University, Stanford, CA, USA. .,Department of Genetics, Stanford University, Stanford, CA, USA.
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29
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Chadani Y, Sugata N, Niwa T, Ito Y, Iwasaki S, Taguchi H. Nascent polypeptide within the exit tunnel stabilizes the ribosome to counteract risky translation. EMBO J 2021; 40:e108299. [PMID: 34672004 PMCID: PMC8634131 DOI: 10.15252/embj.2021108299] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 09/21/2021] [Accepted: 09/29/2021] [Indexed: 01/26/2023] Open
Abstract
Continuous translation elongation, irrespective of amino acid sequences, is a prerequisite for living organisms to produce their proteomes. However, nascent polypeptide products bear an inherent risk of elongation abortion. For example, negatively charged sequences with occasional intermittent prolines, termed intrinsic ribosome destabilization (IRD) sequences, weaken the translating ribosomal complex, causing certain nascent chain sequences to prematurely terminate translation. Here, we show that most potential IRD sequences in the middle of open reading frames remain cryptic and do not interrupt translation, due to two features of the nascent polypeptide. Firstly, the nascent polypeptide itself spans the exit tunnel, and secondly, its bulky amino acid residues occupy the tunnel entrance region, thereby serving as a bridge and protecting the large and small ribosomal subunits from dissociation. Thus, nascent polypeptide products have an inbuilt ability to ensure elongation continuity.
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Affiliation(s)
- Yuhei Chadani
- Cell Biology CenterInstitute of Innovative ResearchTokyo Institute of TechnologyYokohamaJapan
| | - Nobuyuki Sugata
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
| | - Tatsuya Niwa
- Cell Biology CenterInstitute of Innovative ResearchTokyo Institute of TechnologyYokohamaJapan
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
| | - Yosuke Ito
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
| | - Shintaro Iwasaki
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchSaitamaJapan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesThe University of TokyoKashiwaJapan
| | - Hideki Taguchi
- Cell Biology CenterInstitute of Innovative ResearchTokyo Institute of TechnologyYokohamaJapan
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
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30
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Leininger SE, Rodriguez J, Vu QV, Jiang Y, Li MS, Deutsch C, O'Brien EP. Ribosome Elongation Kinetics of Consecutively Charged Residues Are Coupled to Electrostatic Force. Biochemistry 2021; 60:3223-3235. [PMID: 34652913 PMCID: PMC8916236 DOI: 10.1021/acs.biochem.1c00507] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The speed of protein synthesis can dramatically change when consecutively charged residues are incorporated into an elongating nascent protein by the ribosome. The molecular origins of this class of allosteric coupling remain unknown. We demonstrate, using multiscale simulations, that positively charged residues generate large forces that move the P-site amino acid away from the A-site amino acid. Negatively charged residues generate forces of similar magnitude but move the A- and P-sites closer together. These conformational changes, respectively, increase and decrease the transition state barrier height to peptide bond formation, explaining how charged residues mechanochemically alter translation speed. This mechanochemical mechanism is consistent with in vivo ribosome profiling data exhibiting proportionality between translation speed and the number of charged residues, experimental data characterizing nascent chain conformations, and a previously published cryo-EM structure of a ribosome-nascent chain complex containing consecutive lysines. These results expand the role of mechanochemistry in translation and provide a framework for interpreting experimental results on translation speed.
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Affiliation(s)
- Sarah E Leininger
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Judith Rodriguez
- Bioinformatics and Genomics Graduate Program, Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania 16802, United States
| | - Quyen V Vu
- Institute of Physics, Polish Academy of Sciences, Warsaw 02-668, Poland
| | - Yang Jiang
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, Warsaw 02-668, Poland
- Institute for Computational Sciences and Technology, Ho Chi Minh City 700000, Vietnam
| | - Carol Deutsch
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Edward P O'Brien
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
- Bioinformatics and Genomics Graduate Program, Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania 16802, United States
- Institute for Computational and Data Sciences, Penn State University, University Park, Pennsylvania 16802, United States
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31
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Zeng F, Li X, Pires-Alves M, Chen X, Hawk CW, Jin H. Conserved heterodimeric GTPase Rbg1/Tma46 promotes efficient translation in eukaryotic cells. Cell Rep 2021; 37:109877. [PMID: 34706231 DOI: 10.1016/j.celrep.2021.109877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/21/2021] [Accepted: 09/30/2021] [Indexed: 11/19/2022] Open
Abstract
Conserved developmentally regulated guanosine triphosphate (GTP)-binding proteins (Drgs) and their binding partner Drg family regulatory proteins (Dfrps) are important for embryonic development, cellular growth control, differentiation, and proliferation. Here, we report that the yeast Drg1/Dfrp1 ortholog Rbg1/Tma46 facilitates translational initiation, elongation, and termination by suppressing prolonged ribosome pausing. Consistent with the genome-wide observations, deletion of Rbg1 exacerbates the growth defect resulting from translation stalling, and Rbg1 stabilizes mRNAs against no-go decay. Furthermore, we provide a cryoelectron microscopy (cryo-EM) structure of the 80S ribosome bound with Rbg1/Tma46 that reveals the molecular interactions responsible for Rbg1/Tma46 function. The Rbg1 subunit binds to the GTPase association center of the ribosome and the A-tRNA, and the N-terminal zinc finger domain of the Tma46 subunit binds to the 40S, establishing an interaction critical for the ribosomal association. Our results answer the fundamental question of how a paused ribosome resumes translation and show that Drg1/Dfrp1 play a critical role in ensuring orderly translation.
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Affiliation(s)
- Fuxing Zeng
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA; Department of Biology, School of Life Sciences, Southern University of Science and Technology, No. 1088 Xueyuan Blvd., Shenzhen 518055, People's Republic of China
| | - Xin Li
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, No. 1088 Xueyuan Blvd., Shenzhen 518055, People's Republic of China
| | - Melissa Pires-Alves
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | - Xin Chen
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | - Christopher W Hawk
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | - Hong Jin
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA; Carl R. Woese Institute for Genomic Biology, 1206 West Gregory Drive, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA.
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32
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Gillen SL, Giacomelli C, Hodge K, Zanivan S, Bushell M, Wilczynska A. Differential regulation of mRNA fate by the human Ccr4-Not complex is driven by coding sequence composition and mRNA localization. Genome Biol 2021; 22:284. [PMID: 34615539 PMCID: PMC8496106 DOI: 10.1186/s13059-021-02494-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 09/10/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Regulation of protein output at the level of translation allows for a rapid adaptation to dynamic changes to the cell's requirements. This precise control of gene expression is achieved by complex and interlinked biochemical processes that modulate both the protein synthesis rate and stability of each individual mRNA. A major factor coordinating this regulation is the Ccr4-Not complex. Despite playing a role in most stages of the mRNA life cycle, no attempt has been made to take a global integrated view of how the Ccr4-Not complex affects gene expression. RESULTS This study has taken a comprehensive approach to investigate post-transcriptional regulation mediated by the Ccr4-Not complex assessing steady-state mRNA levels, ribosome position, mRNA stability, and protein production transcriptome-wide. Depletion of the scaffold protein CNOT1 results in a global upregulation of mRNA stability and the preferential stabilization of mRNAs enriched for G/C-ending codons. We also uncover that mRNAs targeted to the ER for their translation have reduced translational efficiency when CNOT1 is depleted, specifically downstream of the signal sequence cleavage site. In contrast, translationally upregulated mRNAs are normally localized in p-bodies, contain disorder-promoting amino acids, and encode nuclear localized proteins. Finally, we identify ribosome pause sites that are resolved or induced by the depletion of CNOT1. CONCLUSIONS We define the key mRNA features that determine how the human Ccr4-Not complex differentially regulates mRNA fate and protein synthesis through a mechanism linked to codon composition, amino acid usage, and mRNA localization.
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Affiliation(s)
- Sarah L Gillen
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- MRC Toxicology Unit, Lancaster Road, Leicester, LE1 9HN, UK
| | - Chiara Giacomelli
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Kelly Hodge
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Sara Zanivan
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Martin Bushell
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK.
| | - Ania Wilczynska
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK.
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33
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Allen GE, Panasenko OO, Villanyi Z, Zagatti M, Weiss B, Pagliazzo L, Huch S, Polte C, Zahoran S, Hughes CS, Pelechano V, Ignatova Z, Collart MA. Not4 and Not5 modulate translation elongation by Rps7A ubiquitination, Rli1 moonlighting, and condensates that exclude eIF5A. Cell Rep 2021; 36:109633. [PMID: 34469733 DOI: 10.1016/j.celrep.2021.109633] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/18/2021] [Accepted: 08/09/2021] [Indexed: 12/13/2022] Open
Abstract
In this work, we show that Not4 and Not5 from the Ccr4-Not complex modulate translation elongation dynamics and change ribosome A-site dwelling occupancy in a codon-dependent fashion. These codon-specific changes in not5Δ cells are very robust and independent of codon position within the mRNA, the overall mRNA codon composition, or changes of mRNA expression levels. They inversely correlate with codon-specific changes in cells depleted for eIF5A and positively correlate with those in cells depleted for ribosome-recycling factor Rli1. Not5 resides in punctate loci, co-purifies with ribosomes and Rli1, but not with eIF5A, and limits mRNA solubility. Overexpression of wild-type or non-complementing Rli1 and loss of Rps7A ubiquitination enable Not4 E3 ligase-dependent translation of polyarginine stretches. We propose that Not4 and Not5 modulate translation elongation dynamics to produce a soluble proteome by Rps7A ubiquitination, dynamic condensates that limit mRNA solubility and exclude eIF5A, and a moonlighting function of Rli1.
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Affiliation(s)
- George E Allen
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland
| | - Olesya O Panasenko
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland
| | - Zoltan Villanyi
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland; Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary
| | - Marina Zagatti
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland
| | - Benjamin Weiss
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland
| | - Lucile Pagliazzo
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland
| | - Susanne Huch
- SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165 Solna, Sweden
| | - Christine Polte
- Institute of Biochemistry and Molecular Biology, University of Hamburg, 20146 Hamburg, Germany
| | - Szabolcs Zahoran
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland; Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary
| | | | - Vicent Pelechano
- SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165 Solna, Sweden
| | - Zoya Ignatova
- Institute of Biochemistry and Molecular Biology, University of Hamburg, 20146 Hamburg, Germany
| | - Martine A Collart
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland.
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34
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Ishikawa K. Multilayered regulation of proteome stoichiometry. Curr Genet 2021; 67:883-890. [PMID: 34382105 PMCID: PMC8592966 DOI: 10.1007/s00294-021-01205-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 01/02/2023]
Abstract
Cellular systems depend on multiprotein complexes whose functionalities require defined stoichiometries of subunit proteins. Proper stoichiometry is achieved by controlling the amount of protein synthesis and degradation even in the presence of genetic perturbations caused by changes in gene dosage. As a consequence of increased gene copy number, excess subunits unassembled into the complex are synthesized and rapidly degraded by the ubiquitin–proteasome system. This mechanism, called protein-level dosage compensation, is widely observed not only under such perturbed conditions but also in unperturbed physiological cells. Recent studies have shown that recognition of unassembled subunits and their selective degradation are intricately regulated. This review summarizes the nature, strategies, and increasing complexity of protein-level dosage compensation and discusses possible mechanisms for controlling proteome stoichiometry in multiple layers of biological processes.
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Affiliation(s)
- Koji Ishikawa
- Center for Molecular Biology, ZMBH-DKFZ Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
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35
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Ho AT, Hurst LD. Effective Population Size Predicts Local Rates but Not Local Mitigation of Read-through Errors. Mol Biol Evol 2021; 38:244-262. [PMID: 32797190 PMCID: PMC7783166 DOI: 10.1093/molbev/msaa210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In correctly predicting that selection efficiency is positively correlated with the effective population size (Ne), the nearly neutral theory provides a coherent understanding of between-species variation in numerous genomic parameters, including heritable error (germline mutation) rates. Does the same theory also explain variation in phenotypic error rates and in abundance of error mitigation mechanisms? Translational read-through provides a model to investigate both issues as it is common, mostly nonadaptive, and has good proxy for rate (TAA being the least leaky stop codon) and potential error mitigation via "fail-safe" 3' additional stop codons (ASCs). Prior theory of translational read-through has suggested that when population sizes are high, weak selection for local mitigation can be effective thus predicting a positive correlation between ASC enrichment and Ne. Contra to prediction, we find that ASC enrichment is not correlated with Ne. ASC enrichment, although highly phylogenetically patchy, is, however, more common both in unicellular species and in genes expressed in unicellular modes in multicellular species. By contrast, Ne does positively correlate with TAA enrichment. These results imply that local phenotypic error rates, not local mitigation rates, are consistent with a drift barrier/nearly neutral model.
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Affiliation(s)
- Alexander T Ho
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
- Corresponding author: E-mail:
| | - Laurence D Hurst
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
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36
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Han P, Shichino Y, Schneider-Poetsch T, Mito M, Hashimoto S, Udagawa T, Kohno K, Yoshida M, Mishima Y, Inada T, Iwasaki S. Genome-wide Survey of Ribosome Collision. Cell Rep 2021; 31:107610. [PMID: 32375038 DOI: 10.1016/j.celrep.2020.107610] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 03/18/2020] [Accepted: 04/13/2020] [Indexed: 12/31/2022] Open
Abstract
Ribosome movement is not always smooth and is rather often impeded. For ribosome pauses, fundamental issues remain to be addressed, including where ribosomes pause on mRNAs, what kind of RNA/amino acid sequence causes this pause, and the physiological significance of this attenuation of protein synthesis. Here, we survey the positions of ribosome collisions caused by ribosome pauses in humans and zebrafish using modified ribosome profiling. Collided ribosomes, i.e., disomes, emerge at various sites: Pro-Pro/Gly/Asp motifs; Arg-X-Lys motifs; stop codons; and 3' untranslated regions. The electrostatic interaction between the charged nascent chain and the ribosome exit tunnel determines the eIF5A-mediated disome rescue at the Pro-Pro sites. In particular, XBP1u, a precursor of endoplasmic reticulum (ER)-stress-responsive transcription factor, shows striking queues of collided ribosomes and thus acts as a degradation substrate by ribosome-associated quality control. Our results provide insight into the causes and consequences of ribosome pause by dissecting collided ribosomes.
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Affiliation(s)
- Peixun Han
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan; RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Yuichi Shichino
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Tilman Schneider-Poetsch
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
| | - Mari Mito
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Satoshi Hashimoto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Tsuyoshi Udagawa
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Kenji Kohno
- Institute for Research Initiatives, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Minoru Yoshida
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan; Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yuichiro Mishima
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Toshifumi Inada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Shintaro Iwasaki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan; RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan.
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Alboushi L, Hackett AP, Naeli P, Bakhti M, Jafarnejad SM. Multifaceted control of mRNA translation machinery in cancer. Cell Signal 2021; 84:110037. [PMID: 33975011 DOI: 10.1016/j.cellsig.2021.110037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/06/2021] [Indexed: 12/15/2022]
Abstract
The mRNA translation machinery is tightly regulated through several, at times overlapping, mechanisms that modulate its efficiency and accuracy. Due to their fast rate of growth and metabolism, cancer cells require an excessive amount of mRNA translation and protein synthesis. However, unfavorable conditions, such as hypoxia, amino acid starvation, and oxidative stress, which are abundant in cancer, as well as many anti-cancer treatments inhibit mRNA translation. Cancer cells adapt to the various internal and environmental stresses by employing specialised transcript-specific translation to survive and gain a proliferative advantage. We will highlight the major signaling pathways and mechanisms of translation that regulate the global or mRNA-specific translation in response to the intra- or extra-cellular signals and stresses that are key components in the process of tumourigenesis.
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Affiliation(s)
- Lilas Alboushi
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Angela P Hackett
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Parisa Naeli
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Seyed Mehdi Jafarnejad
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK.
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Mizuno M, Ebine S, Shounai O, Nakajima S, Tomomatsu S, Ikeuchi K, Matsuo Y, Inada T. The nascent polypeptide in the 60S subunit determines the Rqc2-dependency of ribosomal quality control. Nucleic Acids Res 2021; 49:2102-2113. [PMID: 33511411 PMCID: PMC7913769 DOI: 10.1093/nar/gkab005] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/28/2020] [Accepted: 01/05/2021] [Indexed: 11/22/2022] Open
Abstract
Ribosome stalling at tandem CGA codons or poly(A) sequences activates quality controls for nascent polypeptides including ribosome-associated quality control (RQC) and no-go mRNA decay (NGD). In RQC pathway, Hel2-dependent uS10 ubiquitination and the RQC-trigger (RQT) complex are essential for subunit dissociation, and Ltn1-dependent ubiquitination of peptidyl-tRNA in the 60S subunit requires Rqc2. Here, we report that polytryptophan sequences induce Rqc2-independent RQC. More than 11 consecutive tryptophan residues induced RQC in a manner dependent on Hel2-mediated ribosome ubiquitination and the RQT complex. Polytryptophan sequence-mediated RQC was not coupled with CAT-tailing, and Rqc2 was not required for Ltn1-dependent degradation of the arrest products. Eight consecutive tryptophan residues located at the region proximal to the peptidyl transferase center in the ribosome tunnel inhibited CAT-tailing by tandem CGA codons. Polytryptophan sequences also induced Hel2-mediated canonical RQC-coupled NGD and RQC-uncoupled NGD outside the stalled ribosomes. We propose that poly-tryptophan sequences induce Rqc2-independent RQC, suggesting that CAT-tailing in the 60S subunit could be modulated by the polypeptide in the ribosome exit tunnel.
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Affiliation(s)
- Masato Mizuno
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shuhei Ebine
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Okuto Shounai
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shizuka Nakajima
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shota Tomomatsu
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Ken Ikeuchi
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Yoshitaka Matsuo
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Toshifumi Inada
- Graduate School of Pharmaceutical Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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39
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Influence of nascent polypeptide positive charges on translation dynamics. Biochem J 2021; 477:2921-2934. [PMID: 32797214 DOI: 10.1042/bcj20200303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 01/05/2023]
Abstract
Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.
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40
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The Arabidopsis NOT4A E3 ligase promotes PGR3 expression and regulates chloroplast translation. Nat Commun 2021; 12:251. [PMID: 33431870 PMCID: PMC7801604 DOI: 10.1038/s41467-020-20506-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 11/30/2020] [Indexed: 12/14/2022] Open
Abstract
Chloroplast function requires the coordinated action of nuclear- and chloroplast-derived proteins, including several hundred nuclear-encoded pentatricopeptide repeat (PPR) proteins that regulate plastid mRNA metabolism. Despite their large number and importance, regulatory mechanisms controlling PPR expression are poorly understood. Here we show that the Arabidopsis NOT4A ubiquitin-ligase positively regulates the expression of PROTON GRADIENT REGULATION 3 (PGR3), a PPR protein required for translating several thylakoid-localised photosynthetic components and ribosome subunits within chloroplasts. Loss of NOT4A function leads to a strong depletion of cytochrome b6f and NAD(P)H dehydrogenase (NDH) complexes, as well as plastid 30 S ribosomes, which reduces mRNA translation and photosynthetic capacity, causing pale-yellow and slow-growth phenotypes. Quantitative transcriptome and proteome analysis of the not4a mutant reveal it lacks PGR3 expression, and that its molecular defects resemble those of a pgr3 mutant. Furthermore, we show that normal plastid function is restored to not4a through transgenic PGR3 expression. Our work identifies NOT4A as crucial for ensuring robust photosynthetic function during development and stress-response, through promoting PGR3 production and chloroplast translation.
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41
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Udagawa T, Seki M, Okuyama T, Adachi S, Natsume T, Noguchi T, Matsuzawa A, Inada T. Failure to Degrade CAT-Tailed Proteins Disrupts Neuronal Morphogenesis and Cell Survival. Cell Rep 2021; 34:108599. [PMID: 33406423 DOI: 10.1016/j.celrep.2020.108599] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 07/24/2020] [Accepted: 12/14/2020] [Indexed: 12/25/2022] Open
Abstract
Ribosome-associated quality control (RQC) relieves stalled ribosomes and eliminates potentially toxic nascent polypeptide chains (NCs) that can cause neurodegeneration. During RQC, RQC2 modifies NCs with a C-terminal alanine and threonine (CAT) tail. CAT tailing promotes ubiquitination of NCs for proteasomal degradation, while RQC failure in budding yeast disrupts proteostasis via CAT-tailed NC aggregation. However, the CAT tail and its cytotoxicity in mammals have remained largely uncharacterized. We demonstrate that NEMF, a mammalian RQC2 homolog, modifies translation products of nonstop mRNAs, major erroneous mRNAs in mammals, with a C-terminal tail mainly composed of alanine with several other amino acids. Overproduction of nonstop mRNAs induces NC aggregation and caspase-3-dependent apoptosis and impairs neuronal morphogenesis, which are ameliorated by NEMF depletion. Moreover, we found that homopolymeric alanine tailing at least partially accounts for CAT-tail cytotoxicity. These findings explain the cytotoxicity of CAT-tailed NCs and demonstrate physiological significance of RQC on proper neuronal morphogenesis and cell survival.
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Affiliation(s)
- Tsuyoshi Udagawa
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
| | - Moeka Seki
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Taku Okuyama
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shungo Adachi
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan
| | - Tohru Natsume
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan
| | - Takuya Noguchi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Atsushi Matsuzawa
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Toshifumi Inada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
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42
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Barros GC, Requião RD, Carneiro RL, Masuda CA, Moreira MH, Rossetto S, Domitrovic T, Palhano FL. Rqc1 and other yeast proteins containing highly positively charged sequences are not targets of the RQC complex. J Biol Chem 2021; 296:100586. [PMID: 33774050 PMCID: PMC8102910 DOI: 10.1016/j.jbc.2021.100586] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 03/12/2021] [Accepted: 03/23/2021] [Indexed: 02/06/2023] Open
Abstract
Previous work has suggested that highly positively charged protein segments coded by rare codons or poly (A) stretches induce ribosome stalling and translational arrest through electrostatic interactions with the negatively charged ribosome exit tunnel, leading to inefficient elongation. This arrest leads to the activation of the Ribosome Quality Control (RQC) pathway and results in low expression of these reporter proteins. However, the only endogenous yeast proteins known to activate the RQC are Rqc1, a protein essential for RQC function, and Sdd1, a protein with unknown function, both of which contain polybasic sequences. To explore the generality of this phenomenon, we investigated whether the RQC complex controls the expression of other proteins with polybasic sequences. We showed by ribosome profiling data analysis and western blot that proteins containing polybasic sequences similar to, or even more positively charged than those of Rqc1 and Sdd1, were not targeted by the RQC complex. We also observed that the previously reported Ltn1-dependent regulation of Rqc1 is posttranslational, independent of the RQC activity. Taken together, our results suggest that RQC should not be regarded as a general regulatory pathway for the expression of highly positively charged proteins in yeast.
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Affiliation(s)
- Géssica C Barros
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Rodrigo D Requião
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Rodolfo L Carneiro
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Claudio A Masuda
- Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Mariana H Moreira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Silvana Rossetto
- Departamento de Ciência da Computação, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Tatiana Domitrovic
- Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
| | - Fernando L Palhano
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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43
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The Protein Kinase A-Dependent Phosphoproteome of the Human Pathogen Aspergillus fumigatus Reveals Diverse Virulence-Associated Kinase Targets. mBio 2020; 11:mBio.02880-20. [PMID: 33323509 PMCID: PMC7773993 DOI: 10.1128/mbio.02880-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PKA is essential for the virulence of eukaryotic human pathogens. Understanding PKA signaling mechanisms is therefore fundamental to deciphering pathogenesis and developing novel therapies. Protein kinase A (PKA) signaling plays a critical role in the growth and development of all eukaryotic microbes. However, few direct targets have been characterized in any organism. The fungus Aspergillus fumigatus is a leading infectious cause of death in immunocompromised patients, but the specific molecular mechanisms responsible for its pathogenesis are poorly understood. We used this important pathogen as a platform for a comprehensive and multifaceted interrogation of both the PKA-dependent whole proteome and phosphoproteome in order to elucidate the mechanisms through which PKA signaling regulates invasive microbial disease. Employing advanced quantitative whole-proteomic and phosphoproteomic approaches with two complementary phosphopeptide enrichment strategies, coupled to an independent PKA interactome analysis, we defined distinct PKA-regulated pathways and identified novel direct PKA targets contributing to pathogenesis. We discovered three previously uncharacterized virulence-associated PKA effectors, including an autophagy-related protein, Atg24; a CCAAT-binding transcriptional regulator, HapB; and a CCR4-NOT complex-associated ubiquitin ligase, Not4. Targeted mutagenesis, combined with in vitro kinase assays, multiple murine infection models, structural modeling, and molecular dynamics simulations, was employed to characterize the roles of these new PKA targets in growth, environmental and antimicrobial stress responses, and pathogenesis in a mammalian system. We also elucidated the molecular mechanisms of PKA regulation for these effectors by defining the functionality of phosphorylation at specific PKA target sites. We have comprehensively characterized the PKA-dependent phosphoproteome and validated PKA targets as direct regulators of infectious disease for the first time in any pathogen, providing new insights into PKA signaling and control over microbial pathogenesis.
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44
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Ribosomal protein S7 ubiquitination during ER stress in yeast is associated with selective mRNA translation and stress outcome. Sci Rep 2020; 10:19669. [PMID: 33184379 PMCID: PMC7661504 DOI: 10.1038/s41598-020-76239-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 10/16/2020] [Indexed: 01/03/2023] Open
Abstract
eIF2α phosphorylation-mediated translational regulation is crucial for global translation repression by various stresses, including the unfolded protein response (UPR). However, translational control during UPR has not been demonstrated in yeast. This study investigated ribosome ubiquitination-mediated translational controls during UPR. Tunicamycin-induced ER stress enhanced the levels of ubiquitination of the ribosomal proteins uS10, uS3 and eS7. Not4-mediated monoubiquitination of eS7A was required for resistance to tunicamycin, whereas E3 ligase Hel2-mediated ubiquitination of uS10 was not. Ribosome profiling showed that the monoubiquitination of eS7A was crucial for translational regulation, including the upregulation of the spliced form of HAC1 (HAC1i) mRNA and the downregulation of Histidine triad NucleoTide-binding 1 (HNT1) mRNA. Downregulation of the deubiquitinating enzyme complex Upb3-Bre5 increased the levels of ubiquitinated eS7A during UPR in an Ire1-independent manner. These findings suggest that the monoubiquitination of ribosomal protein eS7A plays a crucial role in translational controls during the ER stress response in yeast.
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45
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Exploring the Complexity of Protein-Level Dosage Compensation that Fine-Tunes Stoichiometry of Multiprotein Complexes. PLoS Genet 2020; 16:e1009091. [PMID: 33112847 PMCID: PMC7652333 DOI: 10.1371/journal.pgen.1009091] [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: 07/18/2019] [Revised: 11/09/2020] [Accepted: 08/31/2020] [Indexed: 11/19/2022] Open
Abstract
Proper control of gene expression levels upon various perturbations is a fundamental aspect of cellular robustness. Protein-level dosage compensation is one mechanism buffering perturbations to stoichiometry of multiprotein complexes through accelerated proteolysis of unassembled subunits. Although N-terminal acetylation- and ubiquitin-mediated proteasomal degradation by the Ac/N-end rule pathway enables selective compensation of excess subunits, it is unclear how widespread this pathway contributes to stoichiometry control. Here we report that dosage compensation depends only partially on the Ac/N-end rule pathway. Our analysis of genetic interactions between 18 subunits and 12 quality control factors in budding yeast demonstrated that multiple E3 ubiquitin ligases and N-acetyltransferases are involved in dosage compensation. We find that N-acetyltransferases-mediated compensation is not simply predictable from N-terminal sequence despite their sequence specificity for N-acetylation. We also find that the compensation of Pop3 and Bet4 is due in large part to a minor N-acetyltransferase NatD. Furthermore, canonical NatD substrates histone H2A/H4 were compensated even in its absence, suggesting N-acetylation-independent stoichiometry control. Our study reveals the complexity and robustness of the stoichiometry control system. Quality control of multiprotein complexes is important for maintaining homeostasis in cellular systems that are based on functional complexes. Proper stoichiometry of multiprotein complexes is achieved by the balance between protein synthesis and degradation. Recent studies showed that translation efficiency tends to scale with stoichiometry of their subunits. On the other hand, although protein N-terminal acetylation- and ubiquitin-mediated proteolysis pathway is involved in selective degradation of excess subunits, it is unclear how widespread this pathway contributes to stoichiometry control due to the lack of a systematic investigation using endogenous proteins. To better understand the landscape of the stoichiometry control system, we examined genetic interactions between 18 subunits and 12 quality control factors (E3 ubiquitin ligases and N-acetyltransferases), in total 114 combinations. Our data suggest that N-acetyltransferases are partially responsible for stoichiometry control and that N-acetylation-independent pathway is also involved in selective degradation of excess subunits. Therefore, this study reveals the complexity and robustness of the stoichiometry control system. Further dissection of this complexity will help to understand the mechanisms buffering gene expression perturbations and shaping proteome stoichiometry.
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46
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A cellular handbook for collided ribosomes: surveillance pathways and collision types. Curr Genet 2020; 67:19-26. [PMID: 33044589 DOI: 10.1007/s00294-020-01111-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 09/12/2020] [Accepted: 09/18/2020] [Indexed: 12/29/2022]
Abstract
Translating ribosomes slow down or completely stall when they encounter obstacles on mRNAs. Such events can lead to ribosomes colliding with each other and forming complexes of two (disome), three (trisome) or more ribosomes. While these events can activate surveillance pathways, it has been unclear if collisions are common on endogenous mRNAs and whether they are usually detected by these cellular pathways. Recent genome-wide surveys of collisions revealed widespread distribution of disomes and trisomes across endogenous mRNAs in eukaryotic cells. Several studies further hinted that the recognition of collisions and response to them by multiple surveillance pathways depend on the context and duration of the ribosome stalling. This review considers recent efforts in the identification of endogenous ribosome collisions and cellular pathways dedicated to sense their severity. We further discuss the potential role of collided ribosomes in modulating co-translational events and contributing to cellular homeostasis.
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47
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Ghosh A, Shcherbik N. Cooperativity between the Ribosome-Associated Chaperone Ssb/RAC and the Ubiquitin Ligase Ltn1 in Ubiquitination of Nascent Polypeptides. Int J Mol Sci 2020; 21:ijms21186815. [PMID: 32957466 PMCID: PMC7554835 DOI: 10.3390/ijms21186815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/12/2020] [Accepted: 09/14/2020] [Indexed: 11/25/2022] Open
Abstract
Eukaryotic cells have evolved multiple mechanisms to detect and eliminate aberrant polypeptides. Co-translational protein surveillance systems play an important role in these mechanisms. These systems include ribosome-associated protein quality control (RQC) that detects aberrant nascent chains stalled on ribosomes and promotes their ubiquitination and degradation by the proteasome, and ribosome-associated chaperone Ssb/RAC, which ensures correct nascent chain folding. Despite the known function of RQC and Ssb/ribosome-associated complex (RAC) in monitoring the quality of newly generated polypeptides, whether they cooperate during initial stages of protein synthesis remains unexplored. Here, we provide evidence that Ssb/RAC and the ubiquitin ligase Ltn1, the major component of RQC, display genetic and functional cooperativity. Overexpression of Ltn1 rescues growth suppression of the yeast strain-bearing deletions of SSB genes during proteotoxic stress. Moreover, Ssb/RAC promotes Ltn1-dependent ubiquitination of nascent chains associated with 80S ribosomal particles but not with translating ribosomes. Consistent with this finding, quantitative western blot analysis revealed lower levels of Ltn1 associated with 80S ribosomes and with free 60S ribosomal subunits in the absence of Ssb/RAC. We propose a mechanism in which Ssb/RAC facilitates recruitment of Ltn1 to ribosomes, likely by detecting aberrations in nascent chains and leading to their ubiquitination and degradation.
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48
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Arribere JA, Kuroyanagi H, Hundley HA. mRNA Editing, Processing and Quality Control in Caenorhabditis elegans. Genetics 2020; 215:531-568. [PMID: 32632025 PMCID: PMC7337075 DOI: 10.1534/genetics.119.301807] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 05/03/2020] [Indexed: 02/06/2023] Open
Abstract
While DNA serves as the blueprint of life, the distinct functions of each cell are determined by the dynamic expression of genes from the static genome. The amount and specific sequences of RNAs expressed in a given cell involves a number of regulated processes including RNA synthesis (transcription), processing, splicing, modification, polyadenylation, stability, translation, and degradation. As errors during mRNA production can create gene products that are deleterious to the organism, quality control mechanisms exist to survey and remove errors in mRNA expression and processing. Here, we will provide an overview of mRNA processing and quality control mechanisms that occur in Caenorhabditis elegans, with a focus on those that occur on protein-coding genes after transcription initiation. In addition, we will describe the genetic and technical approaches that have allowed studies in C. elegans to reveal important mechanistic insight into these processes.
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Affiliation(s)
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan, and
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Indiana 47405
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49
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Disome and Trisome Profiling Reveal Genome-wide Targets of Ribosome Quality Control. Mol Cell 2020; 79:588-602.e6. [PMID: 32615089 DOI: 10.1016/j.molcel.2020.06.010] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 04/07/2020] [Accepted: 06/02/2020] [Indexed: 01/18/2023]
Abstract
The ribosome-associated protein quality control (RQC) system that resolves stalled translation events is activated when ribosomes collide and form disome, trisome, or higher-order complexes. However, it is unclear whether this system distinguishes collision complexes formed on defective mRNAs from those with functional roles on endogenous transcripts. Here, we performed disome and trisome footprint profiling in yeast and found collisions were enriched on diverse sequence motifs known to slow translation. When 60S recycling was inhibited, disomes accumulated at stop codons and could move into the 3' UTR to reinitiate translation. The ubiquitin ligase and RQC factor Hel2/ZNF598 generally recognized collisions but did not induce degradation of endogenous transcripts. However, loss of Hel2 triggered the integrated stress response, via phosphorylation of eIF2α, thus linking these pathways. Our results suggest that Hel2 has a role in sensing ribosome collisions on endogenous mRNAs, and such events may be important for cellular homeostasis.
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50
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Abstract
Stalled protein synthesis produces defective nascent chains that can harm cells. In response, cells degrade these nascent chains via a process called ribosome-associated quality control (RQC). Here, we review the irregularities in the translation process that cause ribosomes to stall as well as how cells use RQC to detect stalled ribosomes, ubiquitylate their tethered nascent chains, and deliver the ubiquitylated nascent chains to the proteasome. We additionally summarize how cells respond to RQC failure.
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Affiliation(s)
- Cole S Sitron
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany;
| | - Onn Brandman
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA;
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