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Díaz-Rullo J, González-Pastor JE. Molecular adaptations specific to extreme halophilic archaea could promote high perchlorate tolerance. Appl Environ Microbiol 2025:e0051225. [PMID: 40340443 DOI: 10.1128/aem.00512-25] [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: 03/11/2025] [Accepted: 04/11/2025] [Indexed: 05/10/2025] Open
Abstract
Perchlorate is a strong chaotropic agent that causes macromolecule denaturation, DNA damage, and oxidative stress. However, perchlorate deliquescence is thought to promote the formation of liquid salt brines, even at hyper-arid and cold environments, such as the Martian regolith. For that reason, the detection of high levels of perchlorate at different locations on the Martian surface led to hypotheses about the existence of Martian microenvironments compatible with life, especially with those organisms tolerant to hyper-salinity and perchlorate. Extreme halophilic archaea have been proposed as the best candidates to inhabit those environments not only due to their high tolerance to salinity and perchlorate, but also because of their resistance to a wide variety of stress conditions. Since specific perchlorate responses remain largely unknown, in this work, we have analyzed the molecular mechanisms of perchlorate tolerance exhibited by the model extreme halophilic archaeon Haloferax volcanii using a transcriptomic approach. We report that perchlorate produced transcriptional effects opposite to those of salinity, and we propose that the "salt-in" strategy could promote high perchlorate tolerance in extreme halophilic archaea due to the intracellular accumulation of KCl, which may shield the chaotropic activity of perchlorate. This natural adaptation would be enhanced by changes in other stress responses like DNA repair, refolding and turnover of damaged proteins, removal of oxidative species, and tRNA modifications, among others. These results may help to understand how life could survive on Mars, now or in the past, and highlight the importance of extreme halophiles in the development of in situ resource utilization systems.IMPORTANCEPerchlorate is a toxic chlorinated compound that promotes the formation of liquid salt brines, even at hyper-arid and cold environments. For the past two decades, different probes have reported high levels of perchlorate salts at multiple locations on the Martian surface, which could facilitate the presence of potentially habitable environments by specific microorganisms capable of tolerating both hyper-salinity and high perchlorate concentrations. Therefore, the significance of this research was to investigate the molecular mechanisms for perchlorate tolerance using the extreme haloarchaeon Haloferax volcanii as a model organism. This analysis leads to the identification of critical genes and pathways involved in perchlorate tolerance and supports that certain molecular adaptations specific to extreme haloarchaea may be responsible for the high levels of perchlorate tolerance exhibited by these microorganisms, serving as a valuable resource for Mars exploration.
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Affiliation(s)
- Jorge Díaz-Rullo
- Department of Molecular Evolution, Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
- University of Alcalá, Polytechnic School, Madrid, Spain
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2
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Kodali S, Sands CM, Guo L, Huang Y, Di Stefano B. Biomolecular condensates in immune cell fate. Nat Rev Immunol 2025:10.1038/s41577-025-01130-z. [PMID: 39875604 DOI: 10.1038/s41577-025-01130-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2025] [Indexed: 01/30/2025]
Abstract
Fate decisions during immune cell development require temporally precise changes in gene expression. Evidence suggests that the dynamic modulation of these changes is associated with the formation of diverse, membrane-less nucleoprotein assemblies that are termed biomolecular condensates. These condensates are thought to orchestrate fate-determining transcriptional and post-transcriptional processes by locally and transiently concentrating DNA or RNA molecules alongside their regulatory proteins. Findings have established a link between condensate formation and the gene regulatory networks that ensure the proper development of immune cells. Conversely, condensate dysregulation has been linked to impaired immune cell fates, including ageing and malignant transformation. This Review explores the putative mechanistic links between condensate assembly and the gene regulatory frameworks that govern normal and pathological development in the immune system.
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Affiliation(s)
- Srikanth Kodali
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, USA
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Caroline M Sands
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, USA
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Lei Guo
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
- Department of Translational Medical Sciences, School of Medicine, Texas A&M University, Houston, TX, USA
| | - Yun Huang
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX, USA
- Department of Translational Medical Sciences, School of Medicine, Texas A&M University, Houston, TX, USA
| | - Bruno Di Stefano
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, USA.
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX, USA.
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA.
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3
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Hurtig JE, Stuart CJ, van Hoof A. Independent neofunctionalization of Dxo1 in Saccharomyces and Candida led to 25S rRNA processing function. RNA (NEW YORK, N.Y.) 2024; 30:1634-1645. [PMID: 39332835 PMCID: PMC11571810 DOI: 10.1261/rna.080210.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Accepted: 09/16/2024] [Indexed: 09/29/2024]
Abstract
Eukaryotic genomes typically encode one member of the DXO/Dxo1/Rai1 family of enzymes, which can hydrolyze the 5' ends of RNAs with a variety of structures that deviate from the canonical 7mGpppN. In contrast, the Saccharomyces genome encodes two family members and the second copy, Dxo1, is a distributive 5' exoribonuclease that is required for the final maturation of the 5' end of 25S rRNA from a 25S' precursor. Here we show that this 25S rRNA maturation function is not conserved across kingdoms, but arose in the budding yeasts. Interestingly, the origin of 25S processing capacity coincides with the duplication of this gene, and this capacity is absent in the nonduplicated genes. Strikingly, two different clades of budding yeasts have undergone parallel evolution: Both duplicated their DXO/Dxo1/Rai1 gene, and in both cases, one copy gained the 25S processing function. This was accompanied by many parallel sequence changes, a remarkable case of reproducible neofunctionalization.
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Affiliation(s)
- Jennifer E Hurtig
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
- UT MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Catherine J Stuart
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Ambro van Hoof
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
- UT MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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4
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Wang L, Chen B, Ma B, Wang Y, Wang H, Sun X, Tan BC. Maize Dek51 encodes a DEAD-box RNA helicase essential for pre-rRNA processing and seed development. Cell Rep 2024; 43:114673. [PMID: 39196780 DOI: 10.1016/j.celrep.2024.114673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 07/09/2024] [Accepted: 08/08/2024] [Indexed: 08/30/2024] Open
Abstract
Pre-rRNA processing is essential to ribosome biosynthesis. However, the processing mechanism is not fully understood in plants. Here, we report a DEAD-box RNA helicase DEK51 that mediates the 3' end processing of 18S and 5.8S pre-rRNA in maize (Zea mays L.). DEK51 is localized in the nucleolus, and loss of DEK51 arrests maize seed development and blocks the 3' end processing of 18S and 5.8S pre-rRNA. DEK51 interacts with putative key factors in nuclear RNA exosome-mediated pre-rRNA processing, including ZmMTR4, ZmSMO4, ZmRRP44A, and ZmRRP6L2. This suggests that DEK51 facilitates pre-rRNA processing by interacting with the exosome. Loss of ZmMTR4 function arrests seed development and blocks the 3' end processing of 18S and 5.8S pre-rRNA, similar to dek51. DEK51 also interacts with endonucleases ZmUTP24 and ZmRCL1, suggesting that it may also be involved in the cleavage at site A2. These results show the critical role of DEK51 in promoting 3' end processing of pre-rRNA.
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Affiliation(s)
- Le Wang
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Baoyin Chen
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Bing Ma
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Yong Wang
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Hongqiu Wang
- National Key Laboratory of Wheat and Maize Crop Science, Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou 450002, China
| | - Xiaotong Sun
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Bao-Cai Tan
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China.
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5
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Gerhalter M, Kofler L, Zisser G, Merl-Pham J, Hauck SM, Bergler H. The novel pre-rRNA detection workflow "Riboprobing" allows simple identification of undescribed RNA species. RNA (NEW YORK, N.Y.) 2024; 30:807-823. [PMID: 38580456 PMCID: PMC11182013 DOI: 10.1261/rna.079912.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 03/16/2024] [Indexed: 04/07/2024]
Abstract
Ribosomes translate mRNA into proteins and are essential for every living organism. In eukaryotes, both ribosomal subunits are rapidly assembled in a strict hierarchical order, starting in the nucleolus with the transcription of a common precursor ribosomal RNA (pre-rRNA). This pre-rRNA encodes three of the four mature rRNAs, which are formed by several, consecutive endonucleolytic and exonucleolytic processing steps. Historically, northern blots are used to analyze the variety of different pre-rRNA species, only allowing rough length estimations. Although this limitation can be overcome with primer extension, both approaches often use radioactivity and are time-consuming and costly. Here, we present "Riboprobing," a linker ligation-based workflow followed by reverse transcription and PCR for easy and fast detection and characterization of pre-rRNA species and their 5' as well as 3' ends. Using standard molecular biology laboratory equipment, "Riboprobing" allows reliable discrimination of pre-rRNA species not resolved by northern blot (e.g., 27SA2, 27SA3, and 27SB pre-rRNA). The method can successfully be used for the analysis of total cell extracts as well as purified pre-ribosomes for a straightforward evaluation of the impact of mutant gene versions or inhibitors. In the course of method development, we identified and characterized a hitherto undescribed aberrant pre-rRNA arising from LiCl inhibition. This pre-rRNA fragment spans from processing site A1 to E, forming a small RNP that lacks most early joining assembly factors. This finding expands our knowledge of how the cell deals with severe pre-rRNA processing defects and demonstrates the strict requirement for the 5'ETS (external transcribed spacer) for the assembly process.
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Affiliation(s)
| | - Lisa Kofler
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Gertrude Zisser
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
| | - Juliane Merl-Pham
- Metabolomics and Proteomics Core, Helmholtz Center Munich, Munich 80939, Germany
| | - Stefanie M Hauck
- Metabolomics and Proteomics Core, Helmholtz Center Munich, Munich 80939, Germany
| | - Helmut Bergler
- Institute of Molecular Biosciences, University of Graz, Graz 8010, Austria
- BioTechMed-Graz, Graz 8010, Austria
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Li J, Xie S, Zhang B, He W, Zhang Y, Wang J, Yang L. UTP23 Is a Promising Prognostic Biomarker and Is Associated with Immune Infiltration in Breast Cancer. Crit Rev Eukaryot Gene Expr 2024; 34:1-15. [PMID: 38305284 DOI: 10.1615/critreveukaryotgeneexpr.2023048311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Breast cancer is one of the malignant tumors with a high incidence and mortality rate among women worldwide, and its prevalence is increasing year by year, posing a serious health risk to women. UTP23 (UTP23 Small Subunit Processome Component) is a nucleolar protein that is essential for ribosome production. As we all know, disruption of ribosome structure and function results in improper protein function, affecting the body's normal physiological processes and promoting cancer growth. However, little research has shown a connection between UTP23 and cancer. We analyzed the mRNA expression of UTP23 in normal tissue and breast cancer using The Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus (GEO) database, and the protein expression of UTP23 using The Human Protein Atlas (HPA) database. Next, we examined the relationship between UTP23 high expression and Overall Survival (OS) using Kaplan-Meier Plotters and enriched 980 differentially expressed genes in UTP23 high and low expression samples using GO/KEGG and GSEA to identify potential biological functions of UTP23 and signaling pathways that it might influence. Finally, we also investigated the relationship between UTP23 and immune infiltration and examined the effect of UTP23 on the proliferation of human breast cancer cell lines by knocking down UTP23. We found that UTP23 levels in breast cancer patient samples were noticeably greater than those in healthy individuals and that high UTP23 levels were strongly linked with poor prognoses (P = 0.008). Functional enrichment analysis revealed that UTP23 expression was connected to the humoral immune response. Besides, UTP23 expression was found to be positively correlated with immune cell infiltration. Furthermore, UTP23 knockdown has been shown to inhibit the proliferation of human breast cancer cells MDA-MB-231 and HCC-1806. Taken together, our study demonstrated that UTP23 is a promising target in detecting and treating breast cancer and is intimately linked to immune infiltration.
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Affiliation(s)
- Jindong Li
- Department of Pharmacy, The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu Province, China
| | - Siman Xie
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Benteng Zhang
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Weiping He
- Department of Pharmacy, The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu Province, China
| | - Yan Zhang
- Department of Pharmacy, The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu Province, China
| | - Jun Wang
- Taizhou People's Hospital Affiliated to Nanjing Medical University
| | - Li Yang
- Department of Oncology, The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu Province, China
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7
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Ragunath M, Shen A, Wei L, Peng J, Thiruvengadam M. Ribosome Biogenesis and Cancer: Insights into NOB1 and PNO1 Mechanisms. Curr Pharm Des 2024; 30:2911-2921. [PMID: 39143880 DOI: 10.2174/0113816128301870240730071910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/30/2024] [Accepted: 05/20/2024] [Indexed: 08/16/2024]
Abstract
Post-transcriptional modifications (PTMs) are pivotal in the regulation of gene expression, and pseudouridylation is emerging as a critical player. This modification, facilitated by enzymes such as NOB1 (PNO1), is integral to ribosome biogenesis. PNO1, in collaboration with the NIN1/RPN12 binding protein 1 homolog (NOB1), is vital for the maturation of ribosomes, transitioning 20S pre-rRNA into functional 18S rRNA. Recent studies have highlighted PNO1's potential involvement in cancer progression; however, its underlying mechanisms remain unclear. Relentless growth characterizing cancer underscores the burgeoning significance of epitranscriptomic modifications, including pseudouridylation, in oncogenesis. Given PNO1's emerging role, it is imperative to delineate its contribution to cancer development to identify novel therapeutic interventions. This review summarizes the current literature regarding the role of PNO1 in cancer progression and its molecular underpinnings in oncogenesis. Overexpression of PNO1 was associated with unfavorable prognosis and increased tumor malignancy. At the molecular level, PNO1 facilitates cancer progression by modulating mRNA stability, alternative splicing, and translation efficiency. Its role in pseudouridylation of oncogenic and tumor-suppressor transcripts further underscores its significance in cancer biology. Although disruption of ribosome biogenesis is known to precipitate oncogenesis, the precise mechanisms by which these alterations contribute to cancer remain unclear. This review elucidates the intricate process of ribosomal small subunit maturation, highlighting the roles of crucial ribosomal proteins (RPs) and RNA-binding proteins (RBPs) as well as the positioning and function of NOB1 and PNO1 within the 40S subunit. The involvement of these components in the maturation of the small subunit (SSU) and their significance in the context of cancer therapeutics has been thoroughly explored. PNO1's burgeoning significance in oncology makes it a potential target for cancer therapies. Strategies aimed at modulating PNO1-mediated pseudouridylation may provide new avenues for cancer treatment. However, further research is essential to unravel the complete spectrum of PNO1 mechanisms in cancer and harness this knowledge for the development of targeted and more efficacious anticancer therapies.
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Affiliation(s)
- Muthu Ragunath
- Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Aling Shen
- Fujian Key Laboratory of Integrative Medicine in Geriatrics, Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Lin Wei
- Fujian Key Laboratory of Integrative Medicine in Geriatrics, Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Jun Peng
- Fujian Key Laboratory of Integrative Medicine in Geriatrics, Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, China
| | - Muthu Thiruvengadam
- Department of Applied Bioscience, College of Life and Environmental Science, Konkuk University, Seoul 05029, Republic of Korea
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Schneider C, Bohnsack KE. Caught in the act-Visualizing ribonucleases during eukaryotic ribosome assembly. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1766. [PMID: 36254602 DOI: 10.1002/wrna.1766] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/22/2022] [Accepted: 09/24/2022] [Indexed: 07/20/2023]
Abstract
Ribosomes are essential macromolecular machines responsible for translating the genetic information encoded in mRNAs into proteins. Ribosomes are composed of ribosomal RNAs and proteins (rRNAs and RPs) and the rRNAs fulfill both catalytic and architectural functions. Excision of the mature eukaryotic rRNAs from their precursor transcript is achieved through a complex series of endoribonucleolytic cleavages and exoribonucleolytic processing steps that are precisely coordinated with other aspects of ribosome assembly. Many ribonucleases involved in pre-rRNA processing have been identified and pre-rRNA processing pathways are relatively well defined. However, momentous advances in cryo-electron microscopy have recently enabled structural snapshots of various pre-ribosomal particles from budding yeast (Saccharomyces cerevisiae) and human cells to be captured and, excitingly, these structures not only allow pre-rRNAs to be observed before and after cleavage events, but also enable ribonucleases to be visualized on their target RNAs. These structural views of pre-rRNA processing in action allow a new layer of understanding of rRNA maturation and how it is coordinated with other aspects of ribosome assembly. They illuminate mechanisms of target recognition by the diverse ribonucleases involved and reveal how the cleavage/processing activities of these enzymes are regulated. In this review, we discuss the new insights into pre-rRNA processing gained by structural analyses and the growing understanding of the mechanisms of ribonuclease regulation. This article is categorized under: Translation > Ribosome Biogenesis RNA Processing > rRNA Processing.
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Affiliation(s)
- Claudia Schneider
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
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9
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Pan M, Xiao T, Xu L, Xie Y, Ge W. UTP18-mediated p21 mRNA instability drives adenoma-carcinoma progression in colorectal cancer. Cell Rep 2023; 42:112423. [PMID: 37086406 DOI: 10.1016/j.celrep.2023.112423] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 01/13/2023] [Accepted: 04/06/2023] [Indexed: 04/23/2023] Open
Abstract
Colorectal cancer (CRC) often develops slowly from adenoma, but the underlying mechanism remains unclear, hampering the prevention or treatment of colorectal adenoma-carcinoma progression. In this study, we use in-depth quantitative proteomics combined with survival analysis, revealing that the ribosome protein U3 small nucleolar RNA-associated protein 18 homolog (UTP18) is consistently upregulated in the progression of colorectal adenoma to carcinoma and is associated with adenoma recurrence, effective serodiagnosis, and poor prognosis of CRC. Furthermore, deSUMOylation induces the nucleocytoplasmic transport of UTP18, driving cell-cycle progression and tumorigenesis via mediation of the instability of p21 mRNA. In addition, the growth and ribosome biogenesis of adenoma organoids is found to be promoted by overexpression of UTP18. Thus, UTP18 contributes to multiple roles in adenogenesis and malignancy of CRC, suggesting that it could be a potential biomarker and drug target for colorectal adenoma and cancer.
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Affiliation(s)
- Meng Pan
- Department of Immunology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing 100005, China
| | - Tixian Xiao
- Department of Colorectal Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | - Lai Xu
- Division of Colorectal Surgery, Department of General Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
| | - Yong Xie
- Department of Immunology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing 100005, China; Department of Orthopedics, The Fourth Medical Center, Chinese PLA General Hospital, Beijing 100853, China; National Clinical Research Center for Orthopedics, Sports Medicine & Rehabilitation, Beijing 100853, China.
| | - Wei Ge
- Department of Immunology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing 100005, China.
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Parker MD, Karbstein K. Quality control ensures fidelity in ribosome assembly and cellular health. J Cell Biol 2023; 222:e202209115. [PMID: 36790396 PMCID: PMC9960125 DOI: 10.1083/jcb.202209115] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/09/2023] [Accepted: 02/02/2023] [Indexed: 02/16/2023] Open
Abstract
The coordinated integration of ribosomal RNA and protein into two functional ribosomal subunits is safeguarded by quality control checkpoints that ensure ribosomes are correctly assembled and functional before they engage in translation. Quality control is critical in maintaining the integrity of ribosomes and necessary to support healthy cell growth and prevent diseases associated with mistakes in ribosome assembly. Its importance is demonstrated by the finding that bypassing quality control leads to misassembled, malfunctioning ribosomes with altered translation fidelity, which change gene expression and disrupt protein homeostasis. In this review, we outline our understanding of quality control within ribosome synthesis and how failure to enforce quality control contributes to human disease. We first provide a definition of quality control to guide our investigation, briefly present the main assembly steps, and then examine stages of assembly that test ribosome function, establish a pass-fail system to evaluate these functions, and contribute to altered ribosome performance when bypassed, and are thus considered "quality control."
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Affiliation(s)
- Melissa D. Parker
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA, USA
- University of Florida—Scripps Biomedical Research, Jupiter, FL, USA
| | - Katrin Karbstein
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA, USA
- University of Florida—Scripps Biomedical Research, Jupiter, FL, USA
- Howard Hughes Medical Institute Faculty Scholar, Howard Hughes Medical Institute, Chevy Chase, MD, USA
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11
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Dörner K, Ruggeri C, Zemp I, Kutay U. Ribosome biogenesis factors-from names to functions. EMBO J 2023; 42:e112699. [PMID: 36762427 PMCID: PMC10068337 DOI: 10.15252/embj.2022112699] [Citation(s) in RCA: 80] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/13/2022] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
The assembly of ribosomal subunits is a highly orchestrated process that involves a huge cohort of accessory factors. Most eukaryotic ribosome biogenesis factors were first identified by genetic screens and proteomic approaches of pre-ribosomal particles in Saccharomyces cerevisiae. Later, research on human ribosome synthesis not only demonstrated that the requirement for many of these factors is conserved in evolution, but also revealed the involvement of additional players, reflecting a more complex assembly pathway in mammalian cells. Yet, it remained a challenge for the field to assign a function to many of the identified factors and to reveal their molecular mode of action. Over the past decade, structural, biochemical, and cellular studies have largely filled this gap in knowledge and led to a detailed understanding of the molecular role that many of the players have during the stepwise process of ribosome maturation. Such detailed knowledge of the function of ribosome biogenesis factors will be key to further understand and better treat diseases linked to disturbed ribosome assembly, including ribosomopathies, as well as different types of cancer.
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Affiliation(s)
- Kerstin Dörner
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,Molecular Life Sciences Ph.D. Program, Zurich, Switzerland
| | - Chiara Ruggeri
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.,RNA Biology Ph.D. Program, Zurich, Switzerland
| | - Ivo Zemp
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Ulrike Kutay
- Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
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12
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Wang T, Chang Y, Zhao K, Dong Q, Yang J. Maize RNA 3'-terminal phosphate cyclase-like protein promotes 18S pre-rRNA cleavage and is important for kernel development. THE PLANT CELL 2022; 34:1957-1979. [PMID: 35167702 PMCID: PMC9048941 DOI: 10.1093/plcell/koac052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Plant ribosomes contain four specialized ribonucleic acids, the 5S, 5.8S, 18S, and 25S ribosomal RNAs (rRNAs). Maturation of the latter three rRNAs requires cooperative processing of a single transcript by several endonucleases and exonucleases at specific sites. In maize (Zea mays), the exact nucleases and components required for rRNA processing remain poorly understood. Here, we characterized a conserved RNA 3'-terminal phosphate cyclase (RCL)-like protein, RCL1, that functions in 18S rRNA maturation. RCL1 is highly expressed in the embryo and endosperm during early seed development. Loss of RCL1 function resulted in lethality due to aborted embryo cell differentiation. We also observed pleiotropic defects in the rcl1 endosperm, including abnormal basal transfer cell layer growth and aleurone cell identity, and reduced storage reserve accumulation. The rcl1 seeds had lower levels of mature 18S rRNA and the related precursors were altered in abundance compared with wild type. Analysis of transcript levels and protein accumulation in rcl1 revealed that the observed lower levels of zein and starch synthesis enzymes mainly resulted from effects at the transcriptional and translational levels, respectively. These results demonstrate that RCL1-mediated 18S pre-rRNA processing is essential for ribosome function and messenger RNA translation during maize seed development.
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Affiliation(s)
- Tao Wang
- School of Life Sciences, The National Engineering Laboratory of Crop Resistance Breeding, Anhui Agricultural University, Hefei 230036, China
| | - Yumei Chang
- School of Life Sciences, The National Engineering Laboratory of Crop Resistance Breeding, Anhui Agricultural University, Hefei 230036, China
| | - Kai Zhao
- School of Life Sciences, The National Engineering Laboratory of Crop Resistance Breeding, Anhui Agricultural University, Hefei 230036, China
| | - Qing Dong
- Anhui Academy of Agricultural Sciences, Hefei 230031, China
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13
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Moraleva AA, Deryabin AS, Rubtsov YP, Rubtsova MP, Dontsova OA. Eukaryotic Ribosome Biogenesis: The 40S Subunit. Acta Naturae 2022; 14:14-30. [PMID: 35441050 PMCID: PMC9013438 DOI: 10.32607/actanaturae.11540] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 02/02/2022] [Indexed: 11/29/2022] Open
Abstract
The formation of eukaryotic ribosomes is a sequential process of ribosomal precursors maturation in the nucleolus, nucleoplasm, and cytoplasm. Hundreds of ribosomal biogenesis factors ensure the accurate processing and formation of the ribosomal RNAs' tertiary structure, and they interact with ribosomal proteins. Most of what we know about the ribosome assembly has been derived from yeast cell studies, and the mechanisms of ribosome biogenesis in eukaryotes are considered quite conservative. Although the main stages of ribosome biogenesis are similar across different groups of eukaryotes, this process in humans is much more complicated owing to the larger size of the ribosomes and pre-ribosomes and the emergence of regulatory pathways that affect their assembly and function. Many of the factors involved in the biogenesis of human ribosomes have been identified using genome-wide screening based on RNA interference. This review addresses the key aspects of yeast and human ribosome biogenesis, using the 40S subunit as an example. The mechanisms underlying these differences are still not well understood, because, unlike yeast, there are no effective methods for characterizing pre-ribosomal complexes in humans. Understanding the mechanisms of human ribosome assembly would have an incidence on a growing number of genetic diseases (ribosomopathies) caused by mutations in the genes encoding ribosomal proteins and ribosome biogenesis factors. In addition, there is evidence that ribosome assembly is regulated by oncogenic signaling pathways, and that defects in the ribosome biogenesis are linked to the activation of tumor suppressors.
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Affiliation(s)
- A. A. Moraleva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - A. S. Deryabin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - Yu. P. Rubtsov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
| | - M. P. Rubtsova
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991 Russia
| | - O. A. Dontsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997 Russia
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991 Russia
- Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
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14
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Black JJ, Johnson AW. Genetics animates structure: leveraging genetic interactions to study the dynamics of ribosome biogenesis. Curr Genet 2021; 67:729-738. [PMID: 33844044 PMCID: PMC11979895 DOI: 10.1007/s00294-021-01187-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 11/26/2022]
Abstract
The assembly of eukaryotic ribosomes follows an assembly line-like pathway in which numerous trans-acting biogenesis factors act on discrete pre-ribosomal intermediates to progressively shape the nascent subunits into their final functional architecture. Recent advances in cryo-electron microscopy have led to high-resolution structures of many pre-ribosomal intermediates; however, these static snapshots do not capture the dynamic transitions between these intermediates. To this end, molecular genetics can be leveraged to reveal how the biogenesis factors drive these dynamic transitions. Here, we briefly review how we recently used the deletion of BUD23 (bud23∆) to understand its role in the assembly of the ribosomal small subunit. The strong growth defect of bud23∆ mutants places a selective pressure on yeast cells for the occurrence of extragenic suppressors that define a network of functional interactions among biogenesis factors. Mapping these suppressing mutations to recently published structures of pre-ribosomal complexes allowed us to contextualize these suppressing mutations and derive a detailed model in which Bud23 promotes a critical transition event to facilitate folding of the central pseudoknot of the small subunit. This mini-review highlights how genetics can be used to understand the dynamics of complex structures, such as the maturing ribosome.
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Affiliation(s)
- Joshua J Black
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA
| | - Arlen W Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA.
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15
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Shanmugam T, Streit D, Schroll F, Kovacevic J, Schleiff E. Dynamics and thermal sensitivity of ribosomal RNA maturation paths in plants. JOURNAL OF EXPERIMENTAL BOTANY 2021:erab434. [PMID: 34591082 DOI: 10.1093/jxb/erab434] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Indexed: 06/13/2023]
Abstract
Ribosome biogenesis is a constitutive fundamental process for cellular function. Its rate of production depends on the rate of maturation of precursor ribosomal RNA (pre-rRNA). The rRNA maturation paths are marked by four dominant rate-limiting intermediates with cell-type variation of the processivity rate. We have identified that high temperature stress in plants, while halting the existing pre-rRNA maturation schemes, also transiently triggers an atypical pathway for 35S pre-rRNA processing. This pathway leads to production of an aberrant precursor rRNA, reminiscent of yeast 24S, encompassing 18S and 5.8S rRNA that do not normally co-occur together at sub-unit levels; this response is elicited specifically by high and not low temperatures. We show this response to be conserved in two other model crop plant species (Rice and Tomato). This pathway persists even after returning to normal growth conditions for 1 hour and is reset between 1-6 hours after stress treatment, likely, due to resumption of normal 35S pre-rRNA synthesis and processing. The heat-induced ITS2 cleavage-derived precursors and stalled P-A2-like precursors were heterogeneous in nature with a fraction containing polymeric (A) tails. Furthermore, high temperature treatment and subsequent fractionation resulted in polysome and precursor rRNA depletion.
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Affiliation(s)
- Thiruvenkadam Shanmugam
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
| | - Deniz Streit
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
| | - Frank Schroll
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
| | - Jelena Kovacevic
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
- Frankfurt Institute for Advanced Studies, D-60438 Frankfurt, Germany
- Buchman Institute for Molecular Life Sciences, Goethe University Frankfurt, 60438 Frankfurt, Germany
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16
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Li X, Zengel JM, Lindahl L. A Novel Model for the RNase MRP-Induced Switch between the Formation of Different Forms of 5.8S rRNA. Int J Mol Sci 2021; 22:6690. [PMID: 34206573 PMCID: PMC8268776 DOI: 10.3390/ijms22136690] [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: 04/27/2021] [Revised: 06/14/2021] [Accepted: 06/17/2021] [Indexed: 01/12/2023] Open
Abstract
Processing of the RNA polymerase I pre-rRNA transcript into the mature 18S, 5.8S, and 25S rRNAs requires removing the "spacer" sequences. The canonical pathway for the removal of the ITS1 spacer involves cleavages at the 3' end of 18S rRNA and at two sites inside ITS1. The process can generate either a long or a short 5.8S rRNA that differs in the number of ITS1 nucleotides retained at the 5.8S 5' end. Here we document a novel pathway to the long 5.8S, which bypasses cleavage within ITS1. Instead, the entire ITS1 is degraded from its 5' end by exonuclease Xrn1. Mutations in RNase MRP increase the accumulation of long relative to short 5.8S rRNA. Traditionally this is attributed to a decreased rate of RNase MRP cleavage at its target in ITS1, called A3. However, results from this work show that the MRP-induced switch between long and short 5.8S rRNA formation occurs even when the A3 site is deleted. Based on this and our published data, we propose that the link between RNase MRP and 5.8S 5' end formation involves RNase MRP cleavage at unknown sites elsewhere in pre-rRNA or in RNA molecules other than pre-rRNA.
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MESH Headings
- DNA, Ribosomal Spacer
- Endoribonucleases
- Gene Expression Regulation, Fungal
- Nucleic Acid Conformation
- RNA Processing, Post-Transcriptional
- RNA, Fungal
- RNA, Ribosomal, 5.8S/chemistry
- RNA, Ribosomal, 5.8S/genetics
- RNA, Ribosomal, 5.8S/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Sequence Deletion
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Affiliation(s)
- Xiao Li
- Department of Biological Sciences, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA; (X.L.); (J.M.Z.)
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Janice M. Zengel
- Department of Biological Sciences, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA; (X.L.); (J.M.Z.)
| | - Lasse Lindahl
- Department of Biological Sciences, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA; (X.L.); (J.M.Z.)
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17
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Bud23 promotes the final disassembly of the small subunit Processome in Saccharomyces cerevisiae. PLoS Genet 2020; 16:e1009215. [PMID: 33306676 PMCID: PMC7758049 DOI: 10.1371/journal.pgen.1009215] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 12/23/2020] [Accepted: 10/21/2020] [Indexed: 01/18/2023] Open
Abstract
The first metastable assembly intermediate of the eukaryotic ribosomal small subunit (SSU) is the SSU Processome, a large complex of RNA and protein factors that is thought to represent an early checkpoint in the assembly pathway. Transition of the SSU Processome towards continued maturation requires the removal of the U3 snoRNA and biogenesis factors as well as ribosomal RNA processing. While the factors that drive these events are largely known, how they do so is not. The methyltransferase Bud23 has a role during this transition, but its function, beyond the nonessential methylation of ribosomal RNA, is not characterized. Here, we have carried out a comprehensive genetic screen to understand Bud23 function. We identified 67 unique extragenic bud23Δ-suppressing mutations that mapped to genes encoding the SSU Processome factors DHR1, IMP4, UTP2 (NOP14), BMS1 and the SSU protein RPS28A. These factors form a physical interaction network that links the binding site of Bud23 to the U3 snoRNA and many of the amino acid substitutions weaken protein-protein and protein-RNA interactions. Importantly, this network links Bud23 to the essential GTPase Bms1, which acts late in the disassembly pathway, and the RNA helicase Dhr1, which catalyzes U3 snoRNA removal. Moreover, particles isolated from cells lacking Bud23 accumulated late SSU Processome factors and ribosomal RNA processing defects. We propose a model in which Bud23 dissociates factors surrounding its binding site to promote SSU Processome progression. Ribosomes are the molecular machines that synthesize proteins and are composed of a large and a small subunit which carry out the essential functions of polypeptide synthesis and mRNA decoding, respectively. Ribosome production is tightly linked to cellular growth as cells must produce enough ribosomes to meet their protein needs. However, ribosome assembly is a metabolically expensive pathway that must be balanced with other cellular energy needs and regulated accordingly. In eukaryotes, the small subunit (SSU) Processome is a metastable intermediate that ultimately progresses towards a mature SSU through the release of biogenesis factors. The decision to progress the SSU Processome is thought to be an early checkpoint in the SSU assembly pathway, but insight into the mechanisms of progression is needed. Previous studies suggest that Bud23 plays an uncharacterized role during SSU Processome progression. Here, we used a genetic approach to understand its function and found that Bud23 is connected to a network of SSU Processome factors that stabilize the particle. Interestingly, two of these factors are enzymes that are needed for progression. We conclude that Bud23 promotes the release of factors surrounding its binding site to induce structural rearrangements during the progression of the SSU Processome.
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18
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Cheng J, Lau B, La Venuta G, Ameismeier M, Berninghausen O, Hurt E, Beckmann R. 90 S pre-ribosome transformation into the primordial 40 S subunit. Science 2020; 369:1470-1476. [PMID: 32943521 DOI: 10.1126/science.abb4119] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/10/2020] [Indexed: 12/25/2022]
Abstract
Production of small ribosomal subunits initially requires the formation of a 90S precursor followed by an enigmatic process of restructuring into the primordial pre-40S subunit. We elucidate this process by biochemical and cryo-electron microscopy analysis of intermediates along this pathway in yeast. First, the remodeling RNA helicase Dhr1 engages the 90S pre-ribosome, followed by Utp24 endonuclease-driven RNA cleavage at site A1, thereby separating the 5'-external transcribed spacer (ETS) from 18S ribosomal RNA. Next, the 5'-ETS and 90S assembly factors become dislodged, but this occurs sequentially, not en bloc. Eventually, the primordial pre-40S emerges, still retaining some 90S factors including Dhr1, now ready to unwind the final small nucleolar U3-18S RNA hybrid. Our data shed light on the elusive 90S to pre-40S transition and clarify the principles of assembly and remodeling of large ribonucleoproteins.
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Affiliation(s)
- Jingdong Cheng
- Gene Center, Department of Biochemistry, University of Munich, 81377 Munich, Germany
| | - Benjamin Lau
- Biochemistry Center (BZH), University of Heidelberg, 69120 Heidelberg, Germany
| | - Giuseppe La Venuta
- Biochemistry Center (BZH), University of Heidelberg, 69120 Heidelberg, Germany
| | - Michael Ameismeier
- Gene Center, Department of Biochemistry, University of Munich, 81377 Munich, Germany
| | - Otto Berninghausen
- Gene Center, Department of Biochemistry, University of Munich, 81377 Munich, Germany
| | - Ed Hurt
- Biochemistry Center (BZH), University of Heidelberg, 69120 Heidelberg, Germany.
| | - Roland Beckmann
- Gene Center, Department of Biochemistry, University of Munich, 81377 Munich, Germany.
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19
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Clerget G, Bourguignon-Igel V, Marmier-Gourrier N, Rolland N, Wacheul L, Manival X, Charron C, Kufel J, Méreau A, Senty-Ségault V, Tollervey D, Lafontaine DLJ, Branlant C, Rederstorff M. Synergistic defects in pre-rRNA processing from mutations in the U3-specific protein Rrp9 and U3 snoRNA. Nucleic Acids Res 2020; 48:3848-3868. [PMID: 31996908 PMCID: PMC7144924 DOI: 10.1093/nar/gkaa066] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 01/17/2020] [Accepted: 01/22/2020] [Indexed: 01/24/2023] Open
Abstract
U3 snoRNA and the associated Rrp9/U3-55K protein are essential for 18S rRNA production by the SSU-processome complex. U3 and Rrp9 are required for early pre-rRNA cleavages at sites A0, A1 and A2, but the mechanism remains unclear. Substitution of Arg 289 in Rrp9 to Ala (R289A) specifically reduced cleavage at sites A1 and A2. Surprisingly, R289 is located on the surface of the Rrp9 β-propeller structure opposite to U3 snoRNA. To understand this, we first characterized the protein-protein interaction network of Rrp9 within the SSU-processome. This identified a direct interaction between the Rrp9 β-propeller domain and Rrp36, the strength of which was reduced by the R289A substitution, implicating this interaction in the observed processing phenotype. The Rrp9 R289A mutation also showed strong synergistic negative interactions with mutations in U3 that destabilize the U3/pre-rRNA base-pair interactions or reduce the length of their linking segments. We propose that the Rrp9 β-propeller and U3/pre-rRNA binding cooperate in the structure or stability of the SSU-processome. Additionally, our analysis of U3 variants gave insights into the function of individual segments of the 5′-terminal 72-nt sequence of U3. We interpret these data in the light of recently reported SSU-processome structures.
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Affiliation(s)
| | | | | | | | - Ludivine Wacheul
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S/FNRS), Université Libre de Bruxelles (ULB), and Center for Microscopy and Molecular Imaging (CMMI), B-6041 Charleroi-Gosselies, Belgium
| | - Xavier Manival
- Université de Lorraine, CNRS, IMoPA, F-54000 Nancy, France
| | | | - Joanna Kufel
- Wellcome Center for Cell Biology, University of Edinburgh, Scotland, UK
| | - Agnès Méreau
- Université de Lorraine, CNRS, IMoPA, F-54000 Nancy, France
| | | | - David Tollervey
- Wellcome Center for Cell Biology, University of Edinburgh, Scotland, UK
| | - Denis L J Lafontaine
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S/FNRS), Université Libre de Bruxelles (ULB), and Center for Microscopy and Molecular Imaging (CMMI), B-6041 Charleroi-Gosselies, Belgium
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20
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Down-regulation of UTP23 promotes paclitaxel resistance and predicts poorer prognosis in ovarian cancer. Pathol Res Pract 2019; 215:152625. [DOI: 10.1016/j.prp.2019.152625] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/26/2019] [Accepted: 09/05/2019] [Indexed: 01/30/2023]
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21
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Khoshnevis S, Liu X, Dattolo MD, Karbstein K. Rrp5 establishes a checkpoint for 60S assembly during 40S maturation. RNA (NEW YORK, N.Y.) 2019; 25:1164-1176. [PMID: 31217256 PMCID: PMC6800521 DOI: 10.1261/rna.071225.119] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/16/2019] [Indexed: 06/09/2023]
Abstract
Even though the RNAs contained in the small (40S) and large (60S) ribosomal subunits are cotranscribed, their assembly proceeds largely separately, involving entirely distinct machineries. Nevertheless, separation of the two subunits, an event that is critical for assembly of the small subunit, is delayed until domain I of the large subunit is transcribed, indicating crosstalk between the two assembly pathways. Here we show that this crosstalk is mediated by the assembly factor Rrp5, one of only three proteins required for assembly of both ribosomal subunits. Quantitative RNA binding and cleavage data demonstrate that early on, Rrp5 blocks separation of the two subunits, and thus 40S maturation by inhibiting the access of Rcl1 to promote cleavage of the nascent rRNA. Upon transcription of domain I of 25S rRNA, the 60S assembly factors Noc1/Noc2 bind both this RNA and Rrp5 to change the Rrp5 RNA binding mode to enable pre-40S rRNA processing. Mutants in the HEAT-repeat domain of Noc1 are deficient in the separation of the subunits, which is rescued by overexpression of wild-type but not inactive Rcl1 in vivo. Thus, Rrp5 establishes a checkpoint for 60S assembly during 40S maturation to ensure balanced levels of the two subunits.
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Affiliation(s)
- Sohail Khoshnevis
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Xin Liu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Maria D Dattolo
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Katrin Karbstein
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
- HHMI Faculty Scholar
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22
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Saramago M, da Costa PJ, Viegas SC, Arraiano CM. The Implication of mRNA Degradation Disorders on Human DISease: Focus on DIS3 and DIS3-Like Enzymes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1157:85-98. [PMID: 31342438 DOI: 10.1007/978-3-030-19966-1_4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
RNA degradation is considered a critical posttranscriptional regulatory checkpoint, maintaining the correct functioning of organisms. When a specific RNA transcript is no longer required in the cell, it is signaled for degradation through a number of highly regulated steps. Ribonucleases (or simply RNases) are key enzymes involved in the control of RNA stability. These enzymes can perform the RNA degradation alone or cooperate with other proteins in RNA degradation complexes. Important findings over the last years have shed light into eukaryotic RNA degradation by members of the RNase II/RNB family of enzymes. DIS3 enzyme belongs to this family and represents one of the catalytic subunits of the multiprotein complex exosome. This RNase has a diverse range of functions, mainly within nuclear RNA metabolism. Humans encode two other DIS3-like enzymes: DIS3L (DIS3L1) and DIS3L2. DIS3L1 also acts in association with the exosome but is strictly cytoplasmic. In contrast, DIS3L2 acts independently of the exosome and shows a distinctive preference for uridylated RNAs. These enzymes have been shown to be involved in important cellular processes, such as mitotic control, and associated with human disorders like cancer. This review shows how the impairment of function of each of these enzymes is implicated in human disease.
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Affiliation(s)
- Margarida Saramago
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Paulo J da Costa
- Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge, Lisboa, Portugal.,Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, University of Lisbon, Lisboa, Portugal
| | - Sandra C Viegas
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
| | - Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
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23
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Rogers SO. Integrated evolution of ribosomal RNAs, introns, and intron nurseries. Genetica 2018; 147:103-119. [PMID: 30578455 DOI: 10.1007/s10709-018-0050-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 12/13/2018] [Indexed: 12/21/2022]
Abstract
The initial components of ribosomes first appeared more than 3.8 billion years ago during a time when many types of RNAs were evolving. While modern ribosomes are complex molecular machines consisting of rRNAs and proteins, they were assembled during early evolution by the association and joining of small functional RNA units. Introns may have provided the means to ligate many of these pieces together. All four classes of introns (group I, group II, spliceosomal, and archaeal) are present in many rRNA gene loci over a broad phylogenetic range. A survey of rRNA intron sequences across the three major life domains suggests that some of the classes of introns may have diverged from one another within rRNA gene loci. Analyses of rRNA sequences revealed self-splicing group I and group II introns are present in ancestral regions of the SSU (small subunit) and LSU (large subunit), whereas spliceosomal and archaeal introns appeared in sections of the rRNA that evolved later. Most classes of introns increased in number for approximately 1 billion years. However, their frequencies are low in the most recently evolved regions added to the SSU and LSU rRNAs. Furthermore, many of the introns appear to have been in the same locations for billions of years, suggesting an ancient origin for these sequences. In this Perspectives paper, I reviewed and analyzed rRNA intron sequences, locations, structural characteristics, and splicing mechanisms; and suggest that rRNA gene loci may have served as evolutionary nurseries for intron formation and diversification.
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Affiliation(s)
- Scott O Rogers
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403, USA.
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24
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Abstract
Ribosomes, which synthesize the proteins of a cell, comprise ribosomal RNA and ribosomal proteins, which coassemble hierarchically during a process termed ribosome biogenesis. Historically, biochemical and molecular biology approaches have revealed how preribosomal particles form and mature in consecutive steps, starting in the nucleolus and terminating after nuclear export into the cytoplasm. However, only recently, due to the revolution in cryo-electron microscopy, could pseudoatomic structures of different preribosomal particles be obtained. Together with in vitro maturation assays, these findings shed light on how nascent ribosomes progress stepwise along a dynamic biogenesis pathway. Preribosomes assemble gradually, chaperoned by a myriad of assembly factors and small nucleolar RNAs, before they reach maturity and enter translation. This information will lead to a better understanding of how ribosome synthesis is linked to other cellular pathways in humans and how it can cause diseases, including cancer, if disturbed.
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Affiliation(s)
- Jochen Baßler
- Biochemistry Center, University of Heidelberg, 69120 Heidelberg, Germany; ,
| | - Ed Hurt
- Biochemistry Center, University of Heidelberg, 69120 Heidelberg, Germany; ,
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25
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Walling LR, Butler JS. Toxins targeting transfer RNAs: Translation inhibition by bacterial toxin-antitoxin systems. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1506. [PMID: 30296016 DOI: 10.1002/wrna.1506] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/07/2018] [Accepted: 08/13/2018] [Indexed: 01/09/2023]
Abstract
Prokaryotic toxin-antitoxin (TA) systems are composed of a protein toxin and its cognate antitoxin. These systems are abundant in bacteria and archaea and play an important role in growth regulation. During favorable growth conditions, the antitoxin neutralizes the toxin's activity. However, during conditions of stress or starvation, the antitoxin is inactivated, freeing the toxin to inhibit growth and resulting in dormancy. One mechanism of growth inhibition used by several TA systems results from targeting transfer RNAs (tRNAs), either through preventing aminoacylation, acetylating the primary amino group, or endonucleolytic cleavage. All of these mechanisms inhibit translation and result in growth arrest. Many of these toxins only act on a specific tRNA or a specific subset of tRNAs; however, more work is necessary to understand the specificity determinants of these toxins. For the toxins whose specificity has been characterized, both sequence and structural components of the tRNA appear important for recognition by the toxin. Questions also remain regarding the mechanisms used by dormant bacteria to resume growth after toxin induction. Rescue of stalled ribosomes by transfer-messenger RNAs, removal of acetylated amino groups from tRNAs, or ligation of cleaved RNA fragments have all been implicated as mechanisms for reversing toxin-induced dormancy. However, the mechanisms of resuming growth after induction of the majority of tRNA targeting toxins are not yet understood. This article is categorized under: Translation > Translation Regulation RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition.
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Affiliation(s)
- Lauren R Walling
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York
| | - J Scott Butler
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York.,Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York.,Center for RNA Biology, University of Rochester Medical Center, Rochester, New York
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Chaker-Margot M. Assembly of the small ribosomal subunit in yeast: mechanism and regulation. RNA (NEW YORK, N.Y.) 2018; 24:881-891. [PMID: 29712726 PMCID: PMC6004059 DOI: 10.1261/rna.066985.118] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The eukaryotic ribosome is made of four intricately folded ribosomal RNAs and 79 proteins. During rapid growth, yeast cells produce an incredible 2000 ribosomes every minute. Ribosome assembly involves more than 200 trans-acting factors, intervening from the transcription of the preribosomal RNA in the nucleolus to late maturation events in the cytoplasm. The biogenesis of the small ribosomal subunit, or 40S, is especially intricate, requiring more than four times the mass of the small subunit in assembly factors for its full maturation. Recent studies have provided new insights into the complex assembly of the 40S subunit. These data from cryo-electron microscopy, X-ray crystallography, and other biochemical and molecular biology methods, have elucidated the role of many factors required in small subunit maturation. Mechanisms of the regulation of ribosome assembly have also emerged from this body of work. This review aims to integrate these new results into an updated view of small subunit biogenesis and its regulation, in yeast, from transcription to the formation of the mature small subunit.
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Affiliation(s)
- Malik Chaker-Margot
- The Rockefeller University, New York, New York 10065, USA
- Tri-Institutional Program in Chemical Biology, New York, New York 10065, USA
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27
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Robinson SR, Viegas SC, Matos RG, Domingues S, Bedir M, Stewart HJS, Chevassut TJ, Oliver AW, Arraiano CM, Newbury SF. DIS3 isoforms vary in their endoribonuclease activity and are differentially expressed within haematological cancers. Biochem J 2018; 475:2091-2105. [PMID: 29802118 PMCID: PMC6024818 DOI: 10.1042/bcj20170962] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/16/2018] [Accepted: 05/24/2018] [Indexed: 11/17/2022]
Abstract
DIS3 (defective in sister chromatid joining) is the catalytic subunit of the exosome, a protein complex involved in the 3'-5' degradation of RNAs. DIS3 is a highly conserved exoribonuclease, also known as Rrp44. Global sequencing studies have identified DIS3 as being mutated in a range of cancers, with a considerable incidence in multiple myeloma. In this work, we have identified two protein-coding isoforms of DIS3. Both isoforms are functionally relevant and result from alternative splicing. They differ from each other in the size of their N-terminal PIN (PilT N-terminal) domain, which has been shown to have endoribonuclease activity and tether DIS3 to the exosome. Isoform 1 encodes a full-length PIN domain, whereas the PIN domain of isoform 2 is shorter and is missing a segment with conserved amino acids. We have carried out biochemical activity assays on both isoforms of full-length DIS3 and the isolated PIN domains. We find that isoform 2, despite missing part of the PIN domain, has greater endonuclease activity compared with isoform 1. Examination of the available structural information allows us to provide a hypothesis to explain this altered behaviour. Our results also show that multiple myeloma patient cells and all cancer cell lines tested have higher levels of isoform 1 compared with isoform 2, whereas acute myeloid leukaemia and chronic myelomonocytic leukaemia patient cells and samples from healthy donors have similar levels of isoforms 1 and 2. Taken together, our data indicate that significant changes in the ratios of the two isoforms could be symptomatic of haematological cancers.
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Affiliation(s)
- Sophie R Robinson
- Medical Research Building, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton BN1 9PS, U.K
| | - Sandra C Viegas
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Rute G Matos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Susana Domingues
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Marisa Bedir
- School of Life Sciences, Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, U.K
| | - Helen J S Stewart
- Medical Research Building, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton BN1 9PS, U.K
| | - Timothy J Chevassut
- Medical Research Building, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton BN1 9PS, U.K
| | - Antony W Oliver
- School of Life Sciences, Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, U.K
| | - Cecilia M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Sarah F Newbury
- Medical Research Building, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton BN1 9PS, U.K.
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Choque E, Schneider C, Gadal O, Dez C. Turnover of aberrant pre-40S pre-ribosomal particles is initiated by a novel endonucleolytic decay pathway. Nucleic Acids Res 2018; 46:4699-4714. [PMID: 29481617 PMCID: PMC5961177 DOI: 10.1093/nar/gky116] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 01/29/2018] [Accepted: 02/09/2018] [Indexed: 01/05/2023] Open
Abstract
Ribosome biogenesis requires more than 200 trans-acting factors to achieve the correct production of the two mature ribosomal subunits. Here, we have identified Efg1 as a novel, nucleolar ribosome biogenesis factor in Saccharomyces cerevisiae that is directly linked to the surveillance of pre-40S particles. Depletion of Efg1 impairs early pre-rRNA processing, leading to a strong decrease in 18S rRNA and 40S subunit levels and an accumulation of the aberrant 23S rRNA. Using Efg1 as bait, we revealed a novel degradation pathway of the 23S rRNA. Co-immunoprecipitation experiments showed that Efg1 is a component of 90S pre-ribosomes, as it is associated with the 35S pre-rRNA and U3 snoRNA, but has stronger affinity for 23S pre-rRNA and its novel degradation intermediate 11S rRNA. 23S is cleaved at a new site, Q1, within the 18S sequence by the endonuclease Utp24, generating 11S and 17S' rRNA. Both of these cleavage products are targeted for degradation by the TRAMP/exosome complexes. Therefore, the Q1 site defines a novel endonucleolytic cleavage site of ribosomal RNA exclusively dedicated to surveillance of pre-ribosomal particles.
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Affiliation(s)
- Elodie Choque
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse Cedex 9, France
| | - Claudia Schneider
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Olivier Gadal
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse Cedex 9, France
| | - Christophe Dez
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse Cedex 9, France
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An W, Du Y, Ye K. Structural and functional analysis of Utp24, an endonuclease for processing 18S ribosomal RNA. PLoS One 2018; 13:e0195723. [PMID: 29641590 PMCID: PMC5895043 DOI: 10.1371/journal.pone.0195723] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/28/2018] [Indexed: 01/05/2023] Open
Abstract
The precursor ribosomal RNA is processed by multiple steps of nucleolytic cleavage to generate mature rRNAs. Utp24 is a PIN domain endonuclease in the early 90S precursor of small ribosomal subunit and is proposed to cleave at sites A1 and A2 of pre-rRNA. Here we determine the crystal structure of Utp24 from Schizosaccharomyces pombe at 2.1 angstrom resolution. Utp24 structurally resembles the ribosome assembly factor Utp23 and both contain a Zn-finger motif. Functional analysis in Saccharomyces cerevisiae shows that depletion of Utp24 disturbs the assembly of 90S and abolishes cleavage at sites A0, A1 and A2. The 90S assembled with inactivated Utp24 is arrested at a post-A0-cleavage state and contains enriched nuclear exosome for degradation of 5' ETS. Despite of high sequence conservation, Utp24 from other organisms is unable to form an active 90S in S. cerevisiae, suggesting that Utp24 needs to be precisely positioned in 90S. Our study provides biochemical and structural insight into the role of Utp24 in 90S assembly and activity.
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Affiliation(s)
- Weidong An
- College of Biological Sciences, China Agricultural University, Beijing, China
- National Institute of Biological Sciences, Beijing, China
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yifei Du
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- * E-mail:
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30
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Assembly and structure of the SSU processome-a nucleolar precursor of the small ribosomal subunit. Curr Opin Struct Biol 2018; 49:85-93. [PMID: 29414516 DOI: 10.1016/j.sbi.2018.01.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 01/11/2018] [Accepted: 01/12/2018] [Indexed: 12/22/2022]
Abstract
The small subunit processome is the first precursor of the small eukaryotic ribosomal subunit. During its assembly in the nucleolus, many ribosome biogenesis factors, an RNA chaperone, and ribosomal proteins associate with the nascent pre-rRNA. Biochemical studies have elucidated the rRNA-subdomain dependent recruitment of these factors during SSU processome assembly and have been complemented by structural studies of the assembled particle. Ribosome biogenesis factors encapsulate and guide subdomains of pre-ribosomal RNA in distinct compartments. This prevents uncoordinated maturation and enables processing of regions not accessible in the mature subunit. By sequentially reducing conformational freedom, flexible proteins facilitate the incorporation of dynamic subcomplexes into a globular particle. Large rearrangements within the SSU processome are required for compaction into the mature small ribosomal subunit.
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31
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Homologous VapC Toxins Inhibit Translation and Cell Growth by Sequence-Specific Cleavage of tRNA fMet. J Bacteriol 2018; 200:JB.00582-17. [PMID: 29109187 DOI: 10.1128/jb.00582-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 10/30/2017] [Indexed: 01/19/2023] Open
Abstract
Type II toxin-antitoxin (TA) systems play a critical role in the establishment and maintenance of bacterial dormancy. They are composed of a protein toxin and its cognate protein antitoxin. They function to regulate growth under conditions of stress, such as starvation or antibiotic treatment. As cellular proteases degrade the antitoxin, which normally binds and neutralizes the toxin, this frees the toxin to act on its cellular targets and arrest bacterial growth. TA systems are of particular concern in regard to pathogenic organisms, such as nontypeable Haemophilus influenzae (NTHi), as dormancy may lead to chronic infections and failure of antibiotic treatment. Many targets of VapC toxins have not been identified, to date, and this knowledge is crucial to understanding how toxins control the establishment and maintenance of bacterial dormancy. Accordingly, we characterized the target specificity of the VapC toxins from the two paralogous NTHi vapBC TA systems. RNA sequencing and Northern blot analysis revealed that VapC1 and VapC2 cleave tRNAfMet in the anticodon loop. Overexpression of tRNAfMet suppresses VapC toxicity, suggesting that translation inhibition results from the depletion of tRNAfMet These experiments also identified base pairs in the tRNAfMet anticodon stem that play a key role in VapC-specific cleavage of the tRNA. Together these findings suggest the potential for NTHi VapC1 and VapC2 to induce dormancy by sequence-specific cleavage of tRNAfMetIMPORTANCE Bacterial persistence is a significant concern in regard to pathogenic organisms, such as nontypeable Haemophilus influenzae, as it can result in recurrent and chronic infections. Toxin-antitoxin systems can lead to persistence by causing bacteria to enter a slow-growing state that renders them antibiotic tolerant. Type II toxin components affect a wide variety of bacterial targets in order to elicit dormancy, and for many toxin-antitoxin systems, these mechanisms are not well understood. Thus, in order to understand how vapBC toxin-antitoxin systems cause dormancy, it is crucial to investigate the substrate specificity of VapC toxins. This study identifies the target of the VapC1 and VapC2 toxins from NTHi and takes important steps toward understanding the specificity of these toxins for their tRNA target.
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32
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Matelska D, Steczkiewicz K, Ginalski K. Comprehensive classification of the PIN domain-like superfamily. Nucleic Acids Res 2017; 45:6995-7020. [PMID: 28575517 PMCID: PMC5499597 DOI: 10.1093/nar/gkx494] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 05/24/2017] [Indexed: 12/21/2022] Open
Abstract
PIN-like domains constitute a widespread superfamily of nucleases, diverse in terms of the reaction mechanism, substrate specificity, biological function and taxonomic distribution. Proteins with PIN-like domains are involved in central cellular processes, such as DNA replication and repair, mRNA degradation, transcription regulation and ncRNA maturation. In this work, we identify and classify the most complete set of PIN-like domains to provide the first comprehensive analysis of sequence–structure–function relationships within the whole PIN domain-like superfamily. Transitive sequence searches using highly sensitive methods for remote homology detection led to the identification of several new families, including representatives of Pfam (DUF1308, DUF4935) and CDD (COG2454), and 23 other families not classified in the public domain databases. Further sequence clustering revealed relationships between individual sequence clusters and showed heterogeneity within some families, suggesting a possible functional divergence. With five structural groups, 70 defined clusters, over 100,000 proteins, and broad biological functions, the PIN domain-like superfamily constitutes one of the largest and most diverse nuclease superfamilies. Detailed analyses of sequences and structures, domain architectures, and genomic contexts allowed us to predict biological function of several new families, including new toxin-antitoxin components, proteins involved in tRNA/rRNA maturation and transcription/translation regulation.
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Affiliation(s)
- Dorota Matelska
- University of Warsaw, CeNT, Laboratory of Bioinformatics and Systems Biology, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Kamil Steczkiewicz
- University of Warsaw, CeNT, Laboratory of Bioinformatics and Systems Biology, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Krzysztof Ginalski
- University of Warsaw, CeNT, Laboratory of Bioinformatics and Systems Biology, Zwirki i Wigury 93, 02-089 Warsaw, Poland
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Cheng J, Kellner N, Berninghausen O, Hurt E, Beckmann R. 3.2-Å-resolution structure of the 90S preribosome before A1 pre-rRNA cleavage. Nat Struct Mol Biol 2017; 24:954-964. [PMID: 28967883 DOI: 10.1038/nsmb.3476] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/04/2017] [Indexed: 12/15/2022]
Abstract
The 40S small ribosomal subunit is cotranscriptionally assembled in the nucleolus as part of a large chaperone complex called the 90S preribosome or small-subunit processome. Here, we present the 3.2-Å-resolution structure of the Chaetomium thermophilum 90S preribosome, which allowed us to build atomic structures for 34 assembly factors, including the Mpp10 complex, Bms1, Utp14 and Utp18, and the complete U3 small nucleolar ribonucleoprotein. Moreover, we visualized the U3 RNA heteroduplexes with a 5' external transcribed spacer (5' ETS) and pre-18S RNA, and their stabilization by 90S factors. Overall, the structure explains how a highly intertwined network of assembly factors and pre-rRNA guide the sequential, independent folding of the individual pre-40S domains while the RNA regions forming the 40S active sites are kept immature. Finally, by identifying the unprocessed A1 cleavage site and the nearby Utp24 endonuclease, we suggest a proofreading model for regulated 5'-ETS separation and 90S-pre-40S transition.
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Affiliation(s)
- Jingdong Cheng
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, University of Munich, Munich, Germany
| | - Nikola Kellner
- Biochemie-Zentrum der Universität Heidelberg, Heidelberg, Germany
| | - Otto Berninghausen
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, University of Munich, Munich, Germany
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, Heidelberg, Germany
| | - Roland Beckmann
- Gene Center Munich and Center of Integrated Protein Science-Munich (CiPS-M), Department of Biochemistry, University of Munich, Munich, Germany
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Ghorbanoghli Z, Nieuwenhuis MH, Houwing-Duistermaat JJ, Jagmohan-Changur S, Hes FJ, Tops CM, Wagner A, Aalfs CM, Verhoef S, Gómez García EB, Sijmons RH, Menko FH, Letteboer TG, Hoogerbrugge N, van Wezel T, Vasen HFA, Wijnen JT. Colorectal cancer risk variants at 8q23.3 and 11q23.1 are associated with disease phenotype in APC mutation carriers. Fam Cancer 2017; 15:563-70. [PMID: 26880076 PMCID: PMC5010832 DOI: 10.1007/s10689-016-9877-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Familial adenomatous polyposis (FAP) is a dominantly inherited syndrome caused by germline mutations in the APC gene and characterized by the development of multiple colorectal adenomas and a high risk of developing colorectal cancer (CRC). The severity of polyposis is correlated with the site of the APC mutation. However, there is also phenotypic variability within families with the same underlying APC mutation, suggesting that additional factors influence the severity of polyposis. Genome-wide association studies identified several single nucleotide polymorphisms (SNPs) that are associated with CRC. We assessed whether these SNPs are associated with polyp multiplicity in proven APC mutation carriers. Sixteen CRC-associated SNPs were analysed in a cohort of 419 APC germline mutation carriers from 182 families. Clinical data were retrieved from the Dutch Polyposis Registry. Allele frequencies of the SNPs were compared for patients with <100 colorectal adenomas versus patients with ≥100 adenomas, using generalized estimating equations with the APC genotype as a covariate. We found a trend of association of two of the tested SNPs with the ≥100 adenoma phenotype: the C alleles of rs16892766 at 8q23.3 (OR 1.71, 95 % CI 1.05-2.76, p = 0.03, dominant model) and rs3802842 at 11q23.1 (OR 1.51, 95 % CI 1.03-2.22, p = 0.04, dominant model). We identified two risk variants that are associated with a more severe phenotype in APC mutation carriers. These risk variants may partly explain the phenotypic variability in families with the same APC gene defect. Further studies with a larger sample size are recommended to evaluate and confirm the phenotypic effect of these SNPs in FAP.
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Affiliation(s)
- Z Ghorbanoghli
- Netherlands Foundation for the Detetion of Hereditary Tumors, Leiden, The Netherlands.
- Department of Gastroenterology and Hepatology, Leiden University Medical Centre, Rijnsburgerweg 10, 2333 AA, Leiden, The Netherlands.
| | - M H Nieuwenhuis
- Netherlands Foundation for the Detetion of Hereditary Tumors, Leiden, The Netherlands
| | - J J Houwing-Duistermaat
- Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands
| | - S Jagmohan-Changur
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - F J Hes
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - C M Tops
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - A Wagner
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - C M Aalfs
- Department of Clinical Genetics, Amsterdam Medical Centre, Amsterdam, The Netherlands
| | - S Verhoef
- Family Cancer Clinic, the Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - E B Gómez García
- Department of Clinical Genetics, University of Maastricht, Maastricht, The Netherlands
| | - R H Sijmons
- Department of Genetics, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - F H Menko
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - T G Letteboer
- Department of Medical Genetics, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - N Hoogerbrugge
- Department of Human Genetics, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - T van Wezel
- Departments of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - H F A Vasen
- Netherlands Foundation for the Detetion of Hereditary Tumors, Leiden, The Netherlands
- Department of Gastroenterology and Hepatology, Leiden University Medical Centre, Rijnsburgerweg 10, 2333 AA, Leiden, The Netherlands
| | - J T Wijnen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
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35
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Eukaryotic ribosome assembly, transport and quality control. Nat Struct Mol Biol 2017; 24:689-699. [PMID: 28880863 DOI: 10.1038/nsmb.3454] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/27/2017] [Indexed: 12/18/2022]
Abstract
Eukaryotic ribosome synthesis is a complex, energy-consuming process that takes place across the nucleolus, nucleoplasm and cytoplasm and requires more than 200 conserved assembly factors. Here, we discuss mechanisms by which the ribosome assembly and nucleocytoplasmic transport machineries collaborate to produce functional ribosomes. We also highlight recent cryo-EM studies that provided unprecedented snapshots of ribosomes during assembly and quality control.
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36
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Wells GR, Weichmann F, Sloan KE, Colvin D, Watkins NJ, Schneider C. The ribosome biogenesis factor yUtp23/hUTP23 coordinates key interactions in the yeast and human pre-40S particle and hUTP23 contains an essential PIN domain. Nucleic Acids Res 2017; 45:4796-4809. [PMID: 28082392 PMCID: PMC5416842 DOI: 10.1093/nar/gkw1344] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/22/2016] [Indexed: 11/30/2022] Open
Abstract
Two proteins with PIN endonuclease domains, yUtp24(Fcf1)/hUTP24 and yUtp23/hUTP23 are essential for early pre-ribosomal (r)RNA cleavages at sites A0, A1/1 and A2/2a in yeast and humans. The yUtp24/hUTP24 PIN endonuclease is proposed to cleave at sites A1/1 and A2/2a, but the enzyme cleaving at site A0 is not known. Yeast yUtp23 contains a degenerate, non-essential PIN domain and functions together with the snR30 snoRNA, while human hUTP23 is associated with U17, the human snR30 counterpart. Using in vivo RNA–protein crosslinking and gel shift experiments, we reveal that yUtp23/hUTP23 makes direct contacts with expansion sequence 6 (ES6) in the 18S rRNA sequence and that yUtp23 interacts with the 3΄ half of the snR30 snoRNA. Protein–protein interaction studies further demonstrated that yeast yUtp23 and human hUTP23 directly interact with the H/ACA snoRNP protein yNhp2/hNHP2, the RNA helicase yRok1/hROK1(DDX52), the ribosome biogenesis factor yRrp7/hRRP7 and yUtp24/hUTP24. yUtp23/hUTP23 could therefore be central to the coordinated integration and release of ES6 binding factors and likely plays a pivotal role in remodeling this pre-rRNA region in both yeast and humans. Finally, studies using RNAi-rescue systems in human cells revealed that intact PIN domain and Zinc finger motifs in human hUTP23 are essential for 18S rRNA maturation.
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Affiliation(s)
- Graeme R Wells
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Franziska Weichmann
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Katherine E Sloan
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - David Colvin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Nicholas J Watkins
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Claudia Schneider
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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37
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Tomecki R, Sikorski PJ, Zakrzewska-Placzek M. Comparison of preribosomal RNA processing pathways in yeast, plant and human cells - focus on coordinated action of endo- and exoribonucleases. FEBS Lett 2017; 591:1801-1850. [PMID: 28524231 DOI: 10.1002/1873-3468.12682] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/14/2017] [Accepted: 05/15/2017] [Indexed: 12/17/2022]
Abstract
Proper regulation of ribosome biosynthesis is mandatory for cellular adaptation, growth and proliferation. Ribosome biogenesis is the most energetically demanding cellular process, which requires tight control. Abnormalities in ribosome production have severe consequences, including developmental defects in plants and genetic diseases (ribosomopathies) in humans. One of the processes occurring during eukaryotic ribosome biogenesis is processing of the ribosomal RNA precursor molecule (pre-rRNA), synthesized by RNA polymerase I, into mature rRNAs. It must not only be accurate but must also be precisely coordinated with other phenomena leading to the synthesis of functional ribosomes: RNA modification, RNA folding, assembly with ribosomal proteins and nucleocytoplasmic RNP export. A multitude of ribosome biogenesis factors ensure that these events take place in a correct temporal order. Among them are endo- and exoribonucleases involved in pre-rRNA processing. Here, we thoroughly present a wide spectrum of ribonucleases participating in rRNA maturation, focusing on their biochemical properties, regulatory mechanisms and substrate specificity. We also discuss cooperation between various ribonucleolytic activities in particular stages of pre-rRNA processing, delineating major similarities and differences between three representative groups of eukaryotes: yeast, plants and humans.
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Affiliation(s)
- Rafal Tomecki
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.,Department of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Poland
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38
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Senissar M, Manav MC, Brodersen DE. Structural conservation of the PIN domain active site across all domains of life. Protein Sci 2017; 26:1474-1492. [PMID: 28508407 DOI: 10.1002/pro.3193] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 01/26/2023]
Abstract
The PIN (PilT N-terminus) domain is a compact RNA-binding protein domain present in all domains of life. This 120-residue domain consists of a central and parallel β sheet surrounded by α helices, which together organize 4-5 acidic residues in an active site that binds one or more divalent metal ions and in many cases has endoribonuclease activity. In bacteria and archaea, the PIN domain is primarily associated with toxin-antitoxin loci, consisting of a toxin (the PIN domain nuclease) and an antitoxin that inhibits the function of the toxin under normal growth conditions. During nutritional or antibiotic stress, the antitoxin is proteolytically degraded causing activation of the PIN domain toxin leading to a dramatic reprogramming of cellular metabolism to cope with the new situation. In eukaryotes, PIN domains are commonly found as parts of larger proteins and are involved in a range of processes involving RNA cleavage, including ribosomal RNA biogenesis and nonsense-mediated mRNA decay. In this review, we provide a comprehensive overview of the structural characteristics of the PIN domain and compare PIN domains from all domains of life in terms of structure, active site architecture, and activity.
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Affiliation(s)
- M Senissar
- Centre for Bacterial Stress Response and Persistence, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus, 8000, Denmark
| | - M C Manav
- Centre for Bacterial Stress Response and Persistence, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus, 8000, Denmark
| | - D E Brodersen
- Centre for Bacterial Stress Response and Persistence, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus, 8000, Denmark
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39
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Zhai B, DuPrez K, Doukov TI, Li H, Huang M, Shang G, Ni J, Gu L, Shen Y, Fan L. Structure and Function of a Novel ATPase that Interacts with Holliday Junction Resolvase Hjc and Promotes Branch Migration. J Mol Biol 2017; 429:1009-1029. [PMID: 28238763 PMCID: PMC5565510 DOI: 10.1016/j.jmb.2017.02.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 01/25/2017] [Accepted: 02/19/2017] [Indexed: 11/15/2022]
Abstract
Holliday junction (HJ) is a hallmark intermediate in DNA recombination and must be processed by dissolution (for double HJ) or resolution to ensure genome stability. Although HJ resolvases have been identified in all domains of life, there is a long-standing effort to search in prokaryotes and eukarya for proteins promoting HJ migration. Here, we report the structural and functional characterization of a novel ATPase, Sulfolobus islandicusPilT N-terminal-domain-containing ATPase (SisPINA), encoded by the gene adjacent to the resolvase Hjc coding gene. PINA is conserved in archaea and vital for S. islandicus viability. Purified SisPINA forms hexameric rings in the crystalline state and in solution, similar to the HJ migration helicase RuvB in Gram-negative bacteria. Structural analysis suggests that ATP binding and hydrolysis cause conformational changes in SisPINA to drive branch migration. Further studies reveal that SisPINA interacts with SisHjc and coordinates HJ migration and cleavage.
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Affiliation(s)
- Binyuan Zhai
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China
| | - Kevin DuPrez
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
| | - Tzanko I Doukov
- Macromolecular Crystallography Group, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94309, USA
| | - Huan Li
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China
| | - Mengting Huang
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China
| | - Guijun Shang
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China
| | - Jinfeng Ni
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China
| | - Yulong Shen
- State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nan Road, Jinan 250100, PR China.
| | - Li Fan
- Department of Biochemistry, University of California, Riverside, CA 92521, USA.
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40
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Sun Q, Zhu X, Qi J, An W, Lan P, Tan D, Chen R, Wang B, Zheng S, Zhang C, Chen X, Zhang W, Chen J, Dong MQ, Ye K. Molecular architecture of the 90S small subunit pre-ribosome. eLife 2017; 6. [PMID: 28244370 PMCID: PMC5354517 DOI: 10.7554/elife.22086] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/26/2017] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic small ribosomal subunits are first assembled into 90S pre-ribosomes. The complete 90S is a gigantic complex with a molecular mass of approximately five megadaltons. Here, we report the nearly complete architecture of Saccharomyces cerevisiae 90S determined from three cryo-electron microscopy single particle reconstructions at 4.5 to 8.7 angstrom resolution. The majority of the density maps were modeled and assigned to specific RNA and protein components. The nascent ribosome is assembled into isolated native-like substructures that are stabilized by abundant assembly factors. The 5' external transcribed spacer and U3 snoRNA nucleate a large subcomplex that scaffolds the nascent ribosome. U3 binds four sites of pre-rRNA, including a novel site on helix 27 but not the 3' side of the central pseudoknot, and crucially organizes the 90S structure. The 90S model provides significant insight into the principle of small subunit assembly and the function of assembly factors. DOI:http://dx.doi.org/10.7554/eLife.22086.001
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Affiliation(s)
- Qi Sun
- PTN Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing, China.,Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China.,National Institute of Biological Sciences, Beijing, China
| | - Xing Zhu
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China
| | - Jia Qi
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China.,National Institute of Biological Sciences, Beijing, China.,Department of Biochemistry and Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Weidong An
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China.,National Institute of Biological Sciences, Beijing, China.,College of Biological Sciences, China Agricultural University, Beijing, China
| | - Pengfei Lan
- National Institute of Biological Sciences, Beijing, China
| | - Dan Tan
- National Institute of Biological Sciences, Beijing, China
| | - Rongchang Chen
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China
| | - Bing Wang
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China.,National Institute of Biological Sciences, Beijing, China
| | - Sanduo Zheng
- National Institute of Biological Sciences, Beijing, China
| | - Cheng Zhang
- National Institute of Biological Sciences, Beijing, China
| | - Xining Chen
- National Institute of Biological Sciences, Beijing, China
| | - Wei Zhang
- National Institute of Biological Sciences, Beijing, China
| | - Jing Chen
- PTN Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing, China.,Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China.,National Institute of Biological Sciences, Beijing, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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41
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Architecture of the 90S Pre-ribosome: A Structural View on the Birth of the Eukaryotic Ribosome. Cell 2017; 166:380-393. [PMID: 27419870 DOI: 10.1016/j.cell.2016.06.014] [Citation(s) in RCA: 166] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/05/2016] [Accepted: 06/01/2016] [Indexed: 12/13/2022]
Abstract
The 90S pre-ribosome is an early biogenesis intermediate formed during co-transcriptional ribosome formation, composed of ∼70 assembly factors and several small nucleolar RNAs (snoRNAs) that associate with nascent pre-rRNA. We report the cryo-EM structure of the Chaetomium thermophilum 90S pre-ribosome, revealing how a network of biogenesis factors including 19 β-propellers and large α-solenoid proteins engulfs the pre-rRNA. Within the 90S pre-ribosome, we identify the UTP-A, UTP-B, Mpp10-Imp3-Imp4, Bms1-Rcl1, and U3 snoRNP modules, which are organized around 5'-ETS and partially folded 18S rRNA. The U3 snoRNP is strategically positioned at the center of the 90S particle to perform its multiple tasks during pre-rRNA folding and processing. The architecture of the elusive 90S pre-ribosome gives unprecedented structural insight into the early steps of pre-rRNA maturation. Nascent rRNA that is co-transcriptionally folded and given a particular shape by encapsulation within a dedicated mold-like structure is reminiscent of how polypeptides use chaperone chambers for their protein folding.
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42
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Zhang L, Wu C, Cai G, Chen S, Ye K. Stepwise and dynamic assembly of the earliest precursors of small ribosomal subunits in yeast. Genes Dev 2016; 30:718-32. [PMID: 26980190 PMCID: PMC4803056 DOI: 10.1101/gad.274688.115] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In this study, Zhang et al. researched how the 90S preribosomal particle is cotranscriptionally assembled in yeast using a novel approach. They determined the assembly point of 65 proteins and the U3, U14, and snR30 snoRNAs, revealing a stepwise and dynamic assembly map, thereby advancing our understanding of small subunit biogenesis. The eukaryotic ribosomal RNA (rRNA) is associated cotranscriptionally with numerous factors into an enormous 90S preribosomal particle that conducts early processing of small ribosomal subunits. The assembly pathway and structure of the 90S particle is poorly understood. Here, we affinity-purified and analyzed the constituents of yeast 90S particles that were assembled on a series of plasmid-encoded 3′-truncated pre-18S RNAs. We determined the assembly point of 65 proteins and the U3, U14, and snR30 small nucleolar RNAs (snoRNAs), revealing a stepwise and dynamic assembly map. The 5′ external transcribed spacer (ETS) alone can nucleate a large complex. When the 18S rRNA is nearly complete, the 90S structure undergoes a dramatic reorganization, releasing U14, snR30, and 14 protein factors that bind earlier. We also identified a reference state of 90S that is fully assembled yet has not undergone 5′ETS processing. The assembly map present here provides a new framework to understand small subunit biogenesis.
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Affiliation(s)
- Liman Zhang
- National Institute of Biological Sciences, Beijing, Beijing 102206, China
| | - Chen Wu
- National Institute of Biological Sciences, Beijing, Beijing 102206, China; College of Biological Sciences, China Agricultural University, Beijing 100193, China; Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Gaihong Cai
- National Institute of Biological Sciences, Beijing, Beijing 102206, China
| | - She Chen
- National Institute of Biological Sciences, Beijing, Beijing 102206, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Tomecki R, Labno A, Drazkowska K, Cysewski D, Dziembowski A. hUTP24 is essential for processing of the human rRNA precursor at site A1, but not at site A0. RNA Biol 2016; 12:1010-29. [PMID: 26237581 DOI: 10.1080/15476286.2015.1073437] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Production of ribosomes relies on more than 200 accessory factors to ensure the proper sequence of steps and faultless assembly of ribonucleoprotein machinery. Among trans-acting factors are numerous enzymes, including ribonucleases responsible for processing the large rRNA precursor synthesized by RNA polymerase I that encompasses sequences corresponding to mature 18S, 5.8S, and 25/28S rRNA. In humans, the identity of most enzymes responsible for individual processing steps, including endoribonucleases that cleave pre-rRNA at specific sites within regions flanking and separating mature rRNA, remains largely unknown. Here, we investigated the role of hUTP24 in rRNA maturation in human cells. hUTP24 is a human homolog of the Saccharomyces cerevisiae putative PIN domain-containing endoribonuclease Utp24 (yUtp24), which was suggested to participate in the U3 snoRNA-dependent processing of yeast pre-rRNA at sites A0, A1, and A2. We demonstrate that hUTP24 interacts to some extent with proteins homologous to the components of the yeast small subunit (SSU) processome. Moreover, mutation in the putative catalytic site of hUTP24 results in slowed growth of cells and reduced metabolic activity. These effects are associated with a defect in biogenesis of the 40S ribosomal subunit, which results from decreased amounts of 18S rRNA as a consequence of inaccurate pre-rRNA processing at the 5'-end of the 18S rRNA segment (site A1). Interestingly, and in contrast to yeast, site A0 located upstream of A1 is efficiently processed upon UTP24 dysfunction. Finally, hUTP24 inactivation leads to aberrant processing of 18S rRNA 2 nucleotides downstream of the normal A1 cleavage site.
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Affiliation(s)
- Rafal Tomecki
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Anna Labno
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Karolina Drazkowska
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Dominik Cysewski
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
| | - Andrzej Dziembowski
- a Institute of Biochemistry and Biophysics; Polish Academy of Sciences ; Warsaw , Poland.,b Institute of Genetics and Biotechnology; Faculty of Biology; University of Warsaw ; Warsaw , Poland
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44
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Wells GR, Weichmann F, Colvin D, Sloan KE, Kudla G, Tollervey D, Watkins NJ, Schneider C. The PIN domain endonuclease Utp24 cleaves pre-ribosomal RNA at two coupled sites in yeast and humans. Nucleic Acids Res 2016; 44:5399-409. [PMID: 27034467 PMCID: PMC4914098 DOI: 10.1093/nar/gkw213] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/18/2016] [Indexed: 11/12/2022] Open
Abstract
During ribosomal RNA (rRNA) maturation, cleavages at defined sites separate the mature rRNAs from spacer regions, but the identities of several enzymes required for 18S rRNA release remain unknown. PilT N-terminus (PIN) domain proteins are frequently endonucleases and the PIN domain protein Utp24 is essential for early cleavages at three pre-rRNA sites in yeast (A0, A1 and A2) and humans (A0, 1 and 2a). In yeast, A1 is cleaved prior to A2 and both cleavages require base-pairing by the U3 snoRNA to the central pseudoknot elements of the 18S rRNA. We found that yeast Utp24 UV-crosslinked in vivo to U3 and the pseudoknot, placing Utp24 close to cleavage at site A1. Yeast and human Utp24 proteins exhibited in vitro endonuclease activity on an RNA substrate containing yeast site A2. Moreover, an intact PIN domain in human UTP24 was required for accurate cleavages at sites 1 and 2a in vivo, whereas mutation of another potential site 2a endonuclease, RCL1, did not affect 18S production. We propose that Utp24 cleaves sites A1/1 and A2/2a in yeast and human cells.
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Affiliation(s)
- Graeme R Wells
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Franziska Weichmann
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - David Colvin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Katherine E Sloan
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Grzegorz Kudla
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Nicholas J Watkins
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Claudia Schneider
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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45
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Kerk D, Silver D, Uhrig RG, Moorhead GBG. "PP2C7s", Genes Most Highly Elaborated in Photosynthetic Organisms, Reveal the Bacterial Origin and Stepwise Evolution of PPM/PP2C Protein Phosphatases. PLoS One 2015; 10:e0132863. [PMID: 26241330 PMCID: PMC4524716 DOI: 10.1371/journal.pone.0132863] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/19/2015] [Indexed: 12/22/2022] Open
Abstract
Mg+2/Mn+2-dependent type 2C protein phosphatases (PP2Cs) are ubiquitous in eukaryotes, mediating diverse cellular signaling processes through metal ion catalyzed dephosphorylation of target proteins. We have identified a distinct PP2C sequence class (“PP2C7s”) which is nearly universally distributed in Eukaryotes, and therefore apparently ancient. PP2C7s are by far most prominent and diverse in plants and green algae. Combining phylogenetic analysis, subcellular localization predictions, and a distillation of publically available gene expression data, we have traced the evolutionary trajectory of this gene family in photosynthetic eukaryotes, demonstrating two major sequence assemblages featuring a succession of increasingly derived sub-clades. These display predominant expression moving from an ancestral pattern in photosynthetic tissues toward non-photosynthetic, specialized and reproductive structures. Gene co-expression network composition strongly suggests a shifting pattern of PP2C7 gene functions, including possible regulation of starch metabolism for one homologue set in Arabidopsis and rice. Distinct plant PP2C7 sub-clades demonstrate novel amino terminal protein sequences upon motif analysis, consistent with a shifting pattern of regulation of protein function. More broadly, neither the major events in PP2C sequence evolution, nor the origin of the diversity of metal binding characteristics currently observed in different PP2C lineages, are clearly understood. Identification of the PP2C7 sequence clade has allowed us to provide a better understanding of both of these issues. Phylogenetic analysis and sequence comparisons using Hidden Markov Models strongly suggest that PP2Cs originated in Bacteria (Group II PP2C sequences), entered Eukaryotes through the ancestral mitochondrial endosymbiosis, elaborated in Eukaryotes, then re-entered Bacteria through an inter-domain gene transfer, ultimately producing bacterial Group I PP2C sequences. A key evolutionary event, occurring first in ancient Eukaryotes, was the acquisition of a conserved aspartate in classic Motif 5. This has been inherited subsequently by PP2C7s, eukaryotic PP2Cs and bacterial Group I PP2Cs, where it is crucial to the formation of a third metal binding pocket, and catalysis.
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Affiliation(s)
- David Kerk
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Dylan Silver
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - R. Glen Uhrig
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Greg B. G. Moorhead
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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Weis BL, Palm D, Missbach S, Bohnsack MT, Schleiff E. atBRX1-1 and atBRX1-2 are involved in an alternative rRNA processing pathway in Arabidopsis thaliana. RNA (NEW YORK, N.Y.) 2015; 21:415-25. [PMID: 25605960 PMCID: PMC4338337 DOI: 10.1261/rna.047563.114] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 12/08/2014] [Indexed: 05/19/2023]
Abstract
Ribosome biogenesis is an essential process in all organisms. In eukaryotes, multiple ribosome biogenesis factors (RBFs) act in the processing of ribosomal (r)RNAs, assembly of ribosomal subunits and their export to the cytoplasm. We characterized two genes in Arabidopsis thaliana coding for orthologs of yeast BRX1, a protein involved in maturation of the large ribosomal subunit. Both atBRX1 proteins, encoded by AT3G15460 and AT1G52930, respectively, are mainly localized in the nucleolus and are ubiquitously expressed throughout plant development and in various tissues. Mutant plant lines for both factors show a delay in development and pointed leaves can be observed in the brx1-2 mutant, implying a link between ribosome biogenesis and plant development. In addition, the pre-rRNA processing is affected in both mutants. Analysis of the pre-rRNA intermediates revealed that early processing steps can occur either in the 5' external transcribed spacer (ETS) or internal transcribed spacer 1 (ITS1). Interestingly, we also find that in xrn2 mutants, early processing events can be bypassed and removal of the 5' ETS is initiated by cleavage at the P' processing site. While the pathways of pre-rRNA processing are comparable to those of yeast and mammalian cells, the balance between the two processing pathways is different in plants. Furthermore, plant-specific steps such as an additional processing site in the 5' ETS, likely post-transcriptional processing of the early cleavage sites and accumulation of a 5' extended 5.8S rRNA not observed in other eukaryotes can be detected.
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Affiliation(s)
- Benjamin L Weis
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany
| | - Denise Palm
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany
| | - Sandra Missbach
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany
| | - Markus T Bohnsack
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany Institute for Molecular Biology, Georg-August University, 37073 Göttingen, Germany
| | - Enrico Schleiff
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, 60438 Frankfurt/Main, Germany Cluster of Excellence Frankfurt, Goethe University, 60438 Frankfurt/Main, Germany Center of Membrane Proteomics, Goethe University, 60438 Frankfurt/Main, Germany
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Hamilton B, Manzella A, Schmidt K, DiMarco V, Butler JS. Analysis of non-typeable Haemophilous influenzae VapC1 mutations reveals structural features required for toxicity and flexibility in the active site. PLoS One 2014; 9:e112921. [PMID: 25391136 PMCID: PMC4229260 DOI: 10.1371/journal.pone.0112921] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/21/2014] [Indexed: 02/06/2023] Open
Abstract
Bacteria have evolved mechanisms that allow them to survive in the face of a variety of stresses including nutrient deprivation, antibiotic challenge and engulfment by predator cells. A switch to dormancy represents one strategy that reduces energy utilization and can render cells resistant to compounds that kill growing bacteria. These persister cells pose a problem during treatment of infections with antibiotics, and dormancy mechanisms may contribute to latent infections. Many bacteria encode toxin-antitoxin (TA) gene pairs that play an important role in dormancy and the formation of persisters. VapBC gene pairs comprise the largest of the Type II TA systems in bacteria and they produce a VapC ribonuclease toxin whose activity is inhibited by the VapB antitoxin. Despite the importance of VapBC TA pairs in dormancy and persister formation, little information exists on the structural features of VapC proteins required for their toxic function in vivo. Studies reported here identified 17 single mutations that disrupt the function of VapC1 from non-typeable H. influenzae in vivo. 3-D modeling suggests that side chains affected by many of these mutations sit near the active site of the toxin protein. Phylogenetic comparisons and secondary mutagenesis indicate that VapC1 toxicity requires an alternative active site motif found in many proteobacteria. Expression of the antitoxin VapB1 counteracts the activity of VapC1 mutants partially defective for toxicity, indicating that the antitoxin binds these mutant proteins in vivo. These findings identify critical chemical features required for the biological function of VapC toxins and PIN-domain proteins.
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Affiliation(s)
- Brooke Hamilton
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Alexander Manzella
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Karyn Schmidt
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Victoria DiMarco
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - J. Scott Butler
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, United States of America
- Center for RNA Biology, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail:
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48
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Fernández-Pevida A, Kressler D, de la Cruz J. Processing of preribosomal RNA in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:191-209. [PMID: 25327757 DOI: 10.1002/wrna.1267] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/02/2014] [Accepted: 09/02/2014] [Indexed: 11/07/2022]
Abstract
Most, if not all RNAs, are transcribed as precursors that require processing to gain functionality. Ribosomal RNAs (rRNA) from all organisms undergo both exo- and endonucleolytic processing. Also, in all organisms, rRNA processing occurs inside large preribosomal particles and is coupled to nucleotide modification, folding of the precursor rRNA (pre-rRNA), and assembly of the ribosomal proteins (r-proteins). In this review, we focus on the processing pathway of pre-rRNAs of cytoplasmic ribosomes in the yeast Saccharomyces cerevisiae, without doubt, the organism where this pathway is best characterized. We summarize the current understanding of the rRNA maturation process, particularly focusing on the pre-rRNA processing sites, the enzymes responsible for the cleavage or trimming reactions and the different mechanisms that monitor and regulate the pathway. Strikingly, the overall order of the various processing steps is reasonably well conserved in eukaryotes, perhaps reflecting common principles for orchestrating the concomitant events of pre-rRNA processing and ribosome assembly.
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Affiliation(s)
- Antonio Fernández-Pevida
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain; Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
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Wang M, Anikin L, Pestov DG. Two orthogonal cleavages separate subunit RNAs in mouse ribosome biogenesis. Nucleic Acids Res 2014; 42:11180-91. [PMID: 25190460 PMCID: PMC4176171 DOI: 10.1093/nar/gku787] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Ribosome biogenesis is a dynamic multistep process, many features of which are still incompletely documented. Here, we show that changes in this pathway can be captured and annotated by means of a graphic set of pre-rRNA ratios, a technique we call Ratio Analysis of Multiple Precursors (RAMP). We find that knocking down a ribosome synthesis factor produces a characteristic RAMP profile that exhibits consistency across a range of depletion levels. This facilitates the inference of affected steps and simplifies comparative analysis. We applied RAMP to examine how endonucleolytic cleavages of the mouse pre-rRNA transcript in the internal transcribed spacer 1 (ITS1) are affected by depletion of factors required for maturation of the small ribosomal subunit (Rcl1, Fcf1/Utp24, Utp23) and the large subunit (Pes1, Nog1). The data suggest that completion of early maturation in a subunit triggers its release from the common pre-rRNA transcript by stimulating cleavage at the proximal site in ITS1. We also find that splitting of pre-rRNA in the 3' region of ITS1 is prevalent in adult mouse tissues and quiescent cells, as it is in human cells. We propose a model for subunit separation during mammalian ribosome synthesis and discuss its implications for understanding pre-rRNA processing pathways.
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Affiliation(s)
- Minshi Wang
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Leonid Anikin
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Dimitri G Pestov
- Department of Cell Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA
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Turowski TW, Tollervey D. Cotranscriptional events in eukaryotic ribosome synthesis. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:129-39. [PMID: 25176256 DOI: 10.1002/wrna.1263] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/16/2014] [Accepted: 07/23/2014] [Indexed: 12/13/2022]
Abstract
Eukaryotic ribosomes are synthesized in a complex, multistep pathway. This begins with transcription of the rDNA genes by a specialized RNA polymerase, accompanied by the cotranscriptional binding of large numbers of ribosome synthesis factors, small nucleolar RNAs and ribosomal proteins. Cleavage of the nascent transcript releases the early pre-40S and pre-60S particles, which acquire export competence in the nucleoplasm prior to translocation through the nuclear pore complexes and final maturation to functional ribosomal subunits in the cytoplasm. This review will focus on the many and complex interactions occurring during pre-rRNA synthesis, particularly in budding yeast in which the pathway is best understood.
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Affiliation(s)
- Tomasz W Turowski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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