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Ochkasova A, Arbuzov G, Kabilov M, Tupikin A, Karpova G, Graifer D. AP lyase activity of the human ribosomal protein uS3: The DNA cleavage sequence specificity and the location of the enzyme active center. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2023; 1871:140880. [PMID: 36396097 DOI: 10.1016/j.bbapap.2022.140880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/10/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022]
Abstract
The human protein uS3, a component of the small ribosomal subunit, has a long-known extra-ribosomal activity as an enzyme of base excision DNA repair displayed in its ability to cleave DNA at abasic (AP) sites. It has been found that the efficacy of DNA cleavage by uS3 in vitro depends on the DNA sequence. To clarify the issue on the sequence specificity of uS3 as an AP lyase in general, we applied a combinatorial approach based on the use of a model single-stranded circular DNA with an AP site flanked with random trinucleotides at both sides. The cleavage of this DNA by uS3 under conditions when only its minor portion undergoes the reaction resulted in the formation of the linear DNA with random triplets at the 5' and 3' termini. NGS sequencing of the DNA library derived from this DNA allowed identifying the contexts within which uS3 cleaves DNA the most and the least effectively. Given that the AP lyase reaction occurs via the formation of a covalent intermediate (Schiff base), we determined the region comprising the active center of the uS3 protein. By digesting of uS3 cross-linked to a radiolabeled AP site-containing model DNA with specific proteolytic agents followed by analysis of the resulting modified oligopeptides, the cross-link was mapped to the region 155-192 (likely, to R173/R178). Thus, our results clarified two previously unstudied features of the uS3 AP lyase activity, one related to the recognition of sequences in DNA surrounding the AP site, and the other to the protein region directly contacting this site.
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Affiliation(s)
- Anastasia Ochkasova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Grigory Arbuzov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Marsel Kabilov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Alexey Tupikin
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Galina Karpova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Dmitri Graifer
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia.
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Temaj G, Hadziselimovic R, Nefic H, Nuhii N. Ribosome biogenesis and ribosome therapy in cancer cells. RESEARCH RESULTS IN PHARMACOLOGY 2022. [DOI: 10.3897/rrpharmacology.8.81706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Introduction: The process of protein synthesis is a vital process for all kingdoms of life. The ribosome is a ribonucleoprotein complex that reads the genetic code, from messenger RNA (mRNA) to produce proteins and to tightly regulate and ensure cells growth. The fact that numerous diseases are caused by defect during the ribosome biogenesis is important to understand this pathway.
Materials and methods: We have analyzed the literature for ribosome biogenesis and its links with different diseases which have been found.
Results and discussion: We have discussed the key aspect of human ribosome biogenesis and its links to diseases. We have also proposed the potential of applying this knowledge to the development of a ribosomal stress-based cancer therapy.
Conclusion: Major challenges in the future will be to determine factors which play a pivotal role during ribosome biogenesis. Therefore, more anti-cancer drugs and gene therapy for genetic diseases will be developed against ribosomal biogenesis in the coming years.
Graphical abstract:
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3
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Mo C, Xie C, Wang G, Tian T, Liu J, Zhu C, Xiao X, Xiao Y. Cyclophilin acts as a ribosome biogenesis factor by chaperoning the ribosomal protein (PlRPS15) in filamentous fungi. Nucleic Acids Res 2021; 49:12358-12376. [PMID: 34792171 PMCID: PMC8643696 DOI: 10.1093/nar/gkab1102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 10/18/2021] [Accepted: 10/22/2021] [Indexed: 11/14/2022] Open
Abstract
The rapid transport of ribosomal proteins (RPs) into the nucleus and their efficient assembly into pre-ribosomal particles are prerequisites for ribosome biogenesis. Proteins that act as dedicated chaperones for RPs to maintain their stability and facilitate their assembly have not been identified in filamentous fungi. PlCYP5 is a nuclear cyclophilin in the nematophagous fungus Purpureocillium lilacinum, whose expression is up-regulated during abiotic stress and nematode egg-parasitism. Here, we found that PlCYP5 co-translationally interacted with the unassembled small ribosomal subunit protein, PlRPS15 (uS19). PlRPS15 contained an eukaryote-specific N-terminal extension that mediated the interaction with PlCYP5. PlCYP5 increased the solubility of PlRPS15 independent of its catalytic peptide-prolyl isomerase function and supported the integration of PlRPS15 into pre-ribosomes. Consistently, the phenotypes of the PlCYP5 loss-of-function mutant were similar to those of the PlRPS15 knockdown mutant (e.g. growth and ribosome biogenesis defects). PlCYP5 homologs in Arabidopsis thaliana, Homo sapiens, Schizosaccharomyces pombe, Sclerotinia sclerotiorum, Botrytis cinerea and Metarhizium anisopliae were identified. Notably, PlCYP5-PlRPS15 homologs from three filamentous fungi interacted with each other but not those from other species. In summary, our data disclosed a unique dedicated chaperone system for RPs by cyclophilin in filamentous fungi.
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Affiliation(s)
- Chenmi Mo
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.,Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Chong Xie
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Gaofeng Wang
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Tian Tian
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Juan Liu
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Chunxiao Zhu
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Xueqiong Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.,Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yannong Xiao
- Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
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Ribosome Biogenesis and Cancer: Overview on Ribosomal Proteins. Int J Mol Sci 2021; 22:ijms22115496. [PMID: 34071057 PMCID: PMC8197113 DOI: 10.3390/ijms22115496] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/16/2021] [Accepted: 05/19/2021] [Indexed: 12/11/2022] Open
Abstract
Cytosolic ribosomes (cytoribosomes) are macromolecular ribonucleoprotein complexes that are assembled from ribosomal RNA and ribosomal proteins, which are essential for protein biosynthesis. Mitochondrial ribosomes (mitoribosomes) perform translation of the proteins essential for the oxidative phosphorylation system. The biogenesis of cytoribosomes and mitoribosomes includes ribosomal RNA processing, modification and binding to ribosomal proteins and is assisted by numerous biogenesis factors. This is a major energy-consuming process in the cell and, therefore, is highly coordinated and sensitive to several cellular stressors. In mitochondria, the regulation of mitoribosome biogenesis is essential for cellular respiration, a process linked to cell growth and proliferation. This review briefly overviews the key stages of cytosolic and mitochondrial ribosome biogenesis; summarizes the main steps of ribosome biogenesis alterations occurring during tumorigenesis, highlighting the changes in the expression level of cytosolic ribosomal proteins (CRPs) and mitochondrial ribosomal proteins (MRPs) in different types of tumors; focuses on the currently available information regarding the extra-ribosomal functions of CRPs and MRPs correlated to cancer; and discusses the role of CRPs and MRPs as biomarkers and/or molecular targets in cancer treatment.
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Saurer M, Ramrath DJF, Niemann M, Calderaro S, Prange C, Mattei S, Scaiola A, Leitner A, Bieri P, Horn EK, Leibundgut M, Boehringer D, Schneider A, Ban N. Mitoribosomal small subunit biogenesis in trypanosomes involves an extensive assembly machinery. Science 2020; 365:1144-1149. [PMID: 31515389 DOI: 10.1126/science.aaw5570] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 07/02/2019] [Accepted: 08/04/2019] [Indexed: 01/02/2023]
Abstract
Mitochondrial ribosomes (mitoribosomes) are large ribonucleoprotein complexes that synthesize proteins encoded by the mitochondrial genome. An extensive cellular machinery responsible for ribosome assembly has been described only for eukaryotic cytosolic ribosomes. Here we report that the assembly of the small mitoribosomal subunit in Trypanosoma brucei involves a large number of factors and proceeds through the formation of assembly intermediates, which we analyzed by using cryo-electron microscopy. One of them is a 4-megadalton complex, referred to as the small subunit assemblosome, in which we identified 34 factors that interact with immature ribosomal RNA (rRNA) and recognize its functionally important regions. The assembly proceeds through large-scale conformational changes in rRNA coupled with successive incorporation of mitoribosomal proteins, providing an example for the complexity of the ribosomal assembly process in mitochondria.
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Affiliation(s)
- Martin Saurer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - David J F Ramrath
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - Moritz Niemann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Salvatore Calderaro
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Céline Prange
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - Simone Mattei
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - Alain Scaiola
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - Alexander Leitner
- Department of Biology, Institute of Molecular Systems Biology, Otto-Stern-Weg 3, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Philipp Bieri
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - Elke K Horn
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Marc Leibundgut
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - Daniel Boehringer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, CH-8093 Zurich, Switzerland.
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Shayan R, Rinaldi D, Larburu N, Plassart L, Balor S, Bouyssié D, Lebaron S, Marcoux J, Gleizes PE, Plisson-Chastang C. Good Vibrations: Structural Remodeling of Maturing Yeast Pre-40S Ribosomal Particles Followed by Cryo-Electron Microscopy. Molecules 2020; 25:molecules25051125. [PMID: 32138239 PMCID: PMC7179242 DOI: 10.3390/molecules25051125] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/24/2020] [Accepted: 02/27/2020] [Indexed: 12/03/2022] Open
Abstract
Assembly of eukaryotic ribosomal subunits is a very complex and sequential process that starts in the nucleolus and finishes in the cytoplasm with the formation of functional ribosomes. Over the past few years, characterization of the many molecular events underlying eukaryotic ribosome biogenesis has been drastically improved by the “resolution revolution” of cryo-electron microscopy (cryo-EM). However, if very early maturation events have been well characterized for both yeast ribosomal subunits, little is known regarding the final maturation steps occurring to the small (40S) ribosomal subunit. To try to bridge this gap, we have used proteomics together with cryo-EM and single particle analysis to characterize yeast pre-40S particles containing the ribosome biogenesis factor Tsr1. Our analyses lead us to refine the timing of the early pre-40S particle maturation steps. Furthermore, we suggest that after an early and structurally stable stage, the beak and platform domains of pre-40S particles enter a “vibrating” or “wriggling” stage, that might be involved in the final maturation of 18S rRNA as well as the fitting of late ribosomal proteins into their mature position.
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Affiliation(s)
- Ramtin Shayan
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
| | - Dana Rinaldi
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
| | - Natacha Larburu
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
| | - Laura Plassart
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
| | - Stéphanie Balor
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
| | - David Bouyssié
- Institut de Pharmacologie et Biologie Structurale, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31062 Toulouse CEDEX, France;
| | - Simon Lebaron
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
| | - Julien Marcoux
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
- Correspondence: (J.M.); (P.-E.G.); (C.P.-C.)
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
- Correspondence: (J.M.); (P.-E.G.); (C.P.-C.)
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062 Toulouse CEDEX, France; (R.S.); (D.R.); (N.L.); (L.P.); (S.B.); (S.L.)
- Correspondence: (J.M.); (P.-E.G.); (C.P.-C.)
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Puf6 and Loc1 Are the Dedicated Chaperones of Ribosomal Protein Rpl43 in Saccharomyces cerevisiae. Int J Mol Sci 2019; 20:ijms20235941. [PMID: 31779129 PMCID: PMC6928942 DOI: 10.3390/ijms20235941] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 11/25/2019] [Accepted: 11/25/2019] [Indexed: 12/11/2022] Open
Abstract
Ribosomal proteins are highly expressed, and the quality of ribosomal proteins must be rigorously controlled to build up a functional ribosome. Rpl43, ribosomal protein large subunit 43, is located nearby the E-site of ribosomes. In our previous study, we found that Puf6, Loc1, and Rpl43 form a trimeric complex in Saccharomyces cerevisiae. Rpl43 protein levels are under-accumulated in the absence of PUF6 or LOC1. However, why the loss of Puf6 or Loc1 decreased the protein levels of Rpl43 remained unclear. In the present study, we further dissected the connections among these three proteins and found that the processing defects of pre-ribosomal RNA in puf6Δ and loc1Δ are similar to those of the mutant with depletion of Rpl43. The stability of newly synthesized Rpl43 protein decreased slightly in puf6Δ and significantly in loc1Δ. We also found that Puf6 and Loc1 could interact with nascent Rpl43 co-translationally via the N-terminus of Rpl43. While the association and dissociation of Rpl43 with karyopherins did not depend on Puf6 and Loc1, Puf6 and Loc1 interacted with nascent Rpl43 in collaboration. While the N-terminus of Puf6 contained nuclear localization signals for transport, the PUF (Pumilio) domain was essential to interaction with Loc1, Rpl43, and 60S subunits. The C-terminus of Loc1 is more important for interaction with Puf6 and Rpl43. In this study, we found that Puf6 and Loc1 are the dedicated chaperones of ribosomal protein Rpl43 and also analyzed the potential interaction domains among the three proteins. Correct formation of the Puf6, Loc1, and Rpl43 ternary complex is required to properly proceed to the next step in 60S biogenesis.
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Tsr4 Is a Cytoplasmic Chaperone for the Ribosomal Protein Rps2 in Saccharomyces cerevisiae. Mol Cell Biol 2019; 39:MCB.00094-19. [PMID: 31182640 DOI: 10.1128/mcb.00094-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 06/03/2019] [Indexed: 01/31/2023] Open
Abstract
Eukaryotic ribosome biogenesis requires the action of approximately 200 trans-acting factors and the incorporation of 79 ribosomal proteins (RPs). The delivery of RPs to preribosomes is a major challenge for the cell because RPs are often highly basic and contain intrinsically disordered regions prone to nonspecific interactions and aggregation. To counteract this, eukaryotes developed dedicated chaperones for certain RPs that promote their solubility and expression, often by binding eukaryote-specific extensions of the RPs. Rps2 (uS5) is a universally conserved RP that assembles into nuclear pre-40S subunits. However, a chaperone for Rps2 had not been identified. Our laboratory previously characterized Tsr4 as a 40S biogenesis factor of unknown function. Here, we report that Tsr4 cotranslationally associates with Rps2. Rps2 harbors a eukaryote-specific N-terminal extension that is critical for its interaction with Tsr4. Moreover, Tsr4 perturbation resulted in decreased Rps2 levels and phenocopied Rps2 depletion. Despite Rps2 joining nuclear pre-40S particles, Tsr4 appears to be restricted to the cytoplasm. Thus, we conclude that Tsr4 is a cytoplasmic chaperone dedicated to Rps2.
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Mitterer V, Shayan R, Ferreira-Cerca S, Murat G, Enne T, Rinaldi D, Weigl S, Omanic H, Gleizes PE, Kressler D, Plisson-Chastang C, Pertschy B. Conformational proofreading of distant 40S ribosomal subunit maturation events by a long-range communication mechanism. Nat Commun 2019; 10:2754. [PMID: 31227701 PMCID: PMC6588571 DOI: 10.1038/s41467-019-10678-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 05/23/2019] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic ribosomes are synthesized in a hierarchical process driven by a plethora of assembly factors, but how maturation events at physically distant sites on pre-ribosomes are coordinated is poorly understood. Using functional analyses and cryo-EM, we show that ribosomal protein Rps20 orchestrates communication between two multi-step maturation events across the pre-40S subunit. Our study reveals that during pre-40S maturation, formation of essential contacts between Rps20 and Rps3 permits assembly factor Ltv1 to recruit the Hrr25 kinase, thereby promoting Ltv1 phosphorylation. In parallel, a deeply buried Rps20 loop reaches to the opposite pre-40S side, where it stimulates Rio2 ATPase activity. Both cascades converge to the final maturation steps releasing Rio2 and phosphorylated Ltv1. We propose that conformational proofreading exerted via Rps20 constitutes a checkpoint permitting assembly factor release and progression of pre-40S maturation only after completion of all earlier maturation steps. The biogenesis of eukaryotic ribosomes is a multi-step process involving the action of more than 200 different ribosome assembly factors. Here the authors show that Rps20 acts as a conduit to coordinate maturation steps across the head domain of the nascent small ribosomal subunit.
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Affiliation(s)
- Valentin Mitterer
- Institute for Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010, Graz, Austria.,Biochemistry Centre, University of Heidelberg, 69120, Heidelberg, Germany
| | - Ramtin Shayan
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse Cedex, France
| | - Sébastien Ferreira-Cerca
- Biochemistry III - Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, 1700, Fribourg, Switzerland
| | - Tanja Enne
- Institute for Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010, Graz, Austria
| | - Dana Rinaldi
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse Cedex, France
| | - Sarah Weigl
- Institute for Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010, Graz, Austria
| | - Hajrija Omanic
- Institute for Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010, Graz, Austria
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse Cedex, France
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, 1700, Fribourg, Switzerland.
| | - Celia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse Cedex, France.
| | - Brigitte Pertschy
- Institute for Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010, Graz, Austria.
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Dionne KL, Bergeron D, Landry-Voyer AM, Bachand F. The 40S ribosomal protein uS5 (RPS2) assembles into an extraribosomal complex with human ZNF277 that competes with the PRMT3-uS5 interaction. J Biol Chem 2018; 294:1944-1955. [PMID: 30530495 DOI: 10.1074/jbc.ra118.004928] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 11/27/2018] [Indexed: 02/06/2023] Open
Abstract
Ribosomal (r)-proteins are generally viewed as ubiquitous, constitutive proteins that simply function to maintain ribosome integrity. However, findings in the past decade have led to the idea that r-proteins have evolved specialized functions beyond the ribosome. For example, the 40S ribosomal protein uS5 (RPS2) is known to form an extraribosomal complex with the protein arginine methyltransferase PRMT3 that is conserved from fission yeast to humans. However, the full scope of uS5's extraribosomal functions, including whether uS5 interacts with any other proteins, is not known. In this study, we identify the conserved zinc finger protein 277 (ZNF277) as a new uS5-associated protein by using quantitative proteomics approaches in human cells. As previously shown for PRMT3, we found that ZNF277 uses a C2H2-type zinc finger domain to recognize uS5. Analysis of protein-protein interactions in living cells indicated that the ZNF277-uS5 complex is found in the cytoplasm and the nucleolus. Furthermore, we show that ZNF277 and PRMT3 compete for uS5 binding, because overexpression of PRMT3 inhibited the formation of the ZNF277-uS5 complex, whereas depletion of cellular ZNF277 resulted in increased levels of uS5-PRMT3. Notably, our results reveal that ZNF277 recognizes nascent uS5 in the course of mRNA translation, suggesting cotranslational assembly of the ZNF277-uS5 complex. Our findings thus unveil an intricate network of evolutionarily conserved protein-protein interactions involving extraribosomal uS5, suggesting a key role for uS5 beyond the ribosome.
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Affiliation(s)
- Kiersten L Dionne
- From the RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Danny Bergeron
- From the RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Anne-Marie Landry-Voyer
- From the RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - François Bachand
- From the RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
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11
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Schütz S, Michel E, Damberger FF, Oplová M, Peña C, Leitner A, Aebersold R, Allain FHT, Panse VG. Molecular basis for disassembly of an importin:ribosomal protein complex by the escortin Tsr2. Nat Commun 2018; 9:3669. [PMID: 30201955 PMCID: PMC6131548 DOI: 10.1038/s41467-018-06160-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/22/2018] [Indexed: 01/16/2023] Open
Abstract
Disordered extensions at the termini and short internal insertions distinguish eukaryotic ribosomal proteins (r-proteins) from their anucleated archaeal counterparts. Here, we report an NMR structure of such a eukaryotic-specific segment (ESS) in the r-protein eS26 in complex with the escortin Tsr2. The structure reveals how ESS attracts Tsr2 specifically to importin:eS26 complexes entering the nucleus in order to trigger non-canonical RanGTP-independent disassembly. Tsr2 then sequesters the released eS26 and prevents rebinding to the importin, providing an alternative allosteric mechanism to terminate the process of nuclear import. Notably, a Diamond–Blackfan anemia-associated Tsr2 mutant protein is impaired in binding to ESS, unveiling a critical role for this interaction in human hematopoiesis. We propose that eS26-ESS and Tsr2 are components of a nuclear sorting system that co-evolved with the emergence of the nucleocytoplasmic barrier and transport carriers. Ribosomal proteins are transported to the nucleus with the help of importins, from which they are released prior to incorporation into the nascent ribosome. Here the authors report the NMR structure of the ribosomal protein eS26 in complex with the escortin Tsr2 and shed light on the mechanism of eS26 release from importin.
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Affiliation(s)
- Sabina Schütz
- Institute of Medical Microbiology, University of Zurich, 8006, Zurich, Switzerland
| | - Erich Michel
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Fred F Damberger
- Institute of Molecular Biology & Biophysics, ETH Zurich, 8093, Zurich, Switzerland
| | - Michaela Oplová
- Institute of Medical Microbiology, University of Zurich, 8006, Zurich, Switzerland.,Institute of Biochemistry, ETH Zurich, 8093, Zurich, Switzerland
| | - Cohue Peña
- Institute of Medical Microbiology, University of Zurich, 8006, Zurich, Switzerland
| | - Alexander Leitner
- Institute of Molecular Systems Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Ruedi Aebersold
- Institute of Molecular Systems Biology, ETH Zurich, 8093, Zurich, Switzerland.,Faculty of Science, University of Zurich, Zurich, 8057, Switzerland
| | - Frederic H-T Allain
- Institute of Molecular Biology & Biophysics, ETH Zurich, 8093, Zurich, Switzerland.
| | - Vikram Govind Panse
- Institute of Medical Microbiology, University of Zurich, 8006, Zurich, Switzerland.
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12
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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: 2.3] [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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13
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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: 158] [Impact Index Per Article: 22.6] [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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14
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Pasquali CC, Islam Z, Adamoski D, Ferreira IM, Righeto RD, Bettini J, Portugal RV, Yue WWY, Gonzalez A, Dias SMG, Ambrosio ALB. The origin and evolution of human glutaminases and their atypical C-terminal ankyrin repeats. J Biol Chem 2017; 292:11572-11585. [PMID: 28526749 DOI: 10.1074/jbc.m117.787291] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/11/2017] [Indexed: 12/14/2022] Open
Abstract
On the basis of tissue-specific enzyme activity and inhibition by catalytic products, Hans Krebs first demonstrated the existence of multiple glutaminases in mammals. Currently, two human genes are known to encode at least four glutaminase isoforms. However, the phylogeny of these medically relevant enzymes remains unclear, prompting us to investigate their origin and evolution. Using prokaryotic and eukaryotic glutaminase sequences, we built a phylogenetic tree whose topology suggested that the multidomain architecture was inherited from bacterial ancestors, probably simultaneously with the hosting of the proto-mitochondrion endosymbiont. We propose an evolutionary model wherein the appearance of the most active enzyme isoform, glutaminase C (GAC), which is expressed in many cancers, was a late retrotransposition event that occurred in fishes from the Chondrichthyes class. The ankyrin (ANK) repeats in the glutaminases were acquired early in their evolution. To obtain information on ANK folding, we solved two high-resolution structures of the ANK repeat-containing C termini of both kidney-type glutaminase (KGA) and GLS2 isoforms (glutaminase B and liver-type glutaminase). We found that the glutaminase ANK repeats form unique intramolecular contacts through two highly conserved motifs; curiously, this arrangement occludes a region usually involved in ANK-mediated protein-protein interactions. We also solved the crystal structure of full-length KGA and present a small-angle X-ray scattering model for full-length GLS2. These structures explain these proteins' compromised ability to assemble into catalytically active supra-tetrameric filaments, as previously shown for GAC. Collectively, these results provide information about glutaminases that may aid in the design of isoform-specific glutaminase inhibitors.
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Affiliation(s)
- Camila Cristina Pasquali
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil
| | - Zeyaul Islam
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil
| | - Douglas Adamoski
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil
| | - Igor Monteze Ferreira
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil.,the Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Ricardo Diogo Righeto
- the Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil.,the School of Electrical and Computer Engineering, University of Campinas, São Paulo 13083-852, Brazil, and
| | - Jefferson Bettini
- the Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil
| | - Rodrigo Villares Portugal
- the Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil
| | - Wyatt Wai-Yin Yue
- the Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Ana Gonzalez
- the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025
| | - Sandra Martha Gomes Dias
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil,
| | - Andre Luis Berteli Ambrosio
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brazil,
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15
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Espinar-Marchena FJ, Babiano R, Cruz J. Placeholder factors in ribosome biogenesis: please, pave my way. MICROBIAL CELL 2017; 4:144-168. [PMID: 28685141 PMCID: PMC5425277 DOI: 10.15698/mic2017.05.572] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The synthesis of cytoplasmic eukaryotic ribosomes is an extraordinarily energy-demanding cellular activity that occurs progressively from the nucleolus to the cytoplasm. In the nucleolus, precursor rRNAs associate with a myriad of trans-acting factors and some ribosomal proteins to form pre-ribosomal particles. These factors include snoRNPs, nucleases, ATPases, GTPases, RNA helicases, and a vast list of proteins with no predicted enzymatic activity. Their coordinate activity orchestrates in a spatiotemporal manner the modification and processing of precursor rRNAs, the rearrangement reactions required for the formation of productive RNA folding intermediates, the ordered assembly of the ribosomal proteins, and the export of pre-ribosomal particles to the cytoplasm; thus, providing speed, directionality and accuracy to the overall process of formation of translation-competent ribosomes. Here, we review a particular class of trans-acting factors known as "placeholders". Placeholder factors temporarily bind selected ribosomal sites until these have achieved a structural context that is appropriate for exchanging the placeholder with another site-specific binding factor. By this strategy, placeholders sterically prevent premature recruitment of subsequently binding factors, premature formation of structures, avoid possible folding traps, and act as molecular clocks that supervise the correct progression of pre-ribosomal particles into functional ribosomal subunits. We summarize the current understanding of those factors that delay the assembly of distinct ribosomal proteins or subsequently bind key sites in pre-ribosomal particles. We also discuss recurrent examples of RNA-protein and protein-protein mimicry between rRNAs and/or factors, which have clear functional implications for the ribosome biogenesis pathway.
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Affiliation(s)
- Francisco J Espinar-Marchena
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| | - Reyes Babiano
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain.,Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
| | - Jesús Cruz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, and Departamento de Genética, Universidad de Sevilla, E-41013, Seville, Spain
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16
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Pertschy B. When a ribosomal protein grows up - the ribosome assembly path of Rps3. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:140-143. [PMID: 28685140 PMCID: PMC5425276 DOI: 10.15698/mic2017.05.571] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 11/29/2022]
Abstract
The biogenesis of ribosomes is a central process in all dividing cells. Eukaryotic ribosomes are composed of a large 60S and a small 40S subunit, each comprising a complex assembly of ribosomal RNA (rRNA) and ribosomal proteins (r-proteins). The synthesis of these constituents is spatially separated, with r-proteins being produced by translation in the cytoplasm, while rRNA is generated by transcription in the nucleus. Hence, the arrangement of r-proteins and rRNA into large ribonucleoprotein complexes requires dedicated mechanisms ensuring their encounter in the same compartment. To this end, r-proteins need to be safely delivered to the nucleus where they assemble with the rRNA. Beyond these initial challenges, the synthesis of ribosomes does not merely comprise the joining of r-proteins with rRNA, but occurs in a complex assembly line involving multiple maturation steps, including the processing and folding of rRNA. R-proteins usually have composite rRNA binding sites, with several different rRNA helices contributing to the full interaction. Not all of these interaction sites may already be accessible at the point when an r-protein is incorporated, necessitating that some of the r-protein-rRNA contacts are formed at later maturation stages. In our two recent studies, we investigated the ribosome assembly path of r-proteins in the yeast Saccharomyces cerevisiae using the small subunit r-protein S3 (Rps3) as a model. Our studies revealed intricate mechanisms to protect the protein, transport it into the nucleus, integrate it into pre-ribosomal precursor particles and promote its final stable association with 40S subunits.
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Affiliation(s)
- Brigitte Pertschy
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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17
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Molecular basis for protection of ribosomal protein L4 from cellular degradation. Nat Commun 2017; 8:14354. [PMID: 28148929 PMCID: PMC5296656 DOI: 10.1038/ncomms14354] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/19/2016] [Indexed: 12/26/2022] Open
Abstract
Eukaryotic ribosome biogenesis requires the nuclear import of ∼80 nascent ribosomal proteins and the elimination of excess amounts by the cellular degradation machinery. Assembly chaperones recognize nascent unassembled ribosomal proteins and transport them together with karyopherins to their nuclear destination. We report the crystal structure of ribosomal protein L4 (RpL4) bound to its dedicated assembly chaperone of L4 (Acl4), revealing extensive interactions sequestering 70 exposed residues of the extended RpL4 loop. The observed molecular recognition fundamentally differs from canonical promiscuous chaperone–substrate interactions. We demonstrate that the eukaryote-specific RpL4 extension harbours overlapping binding sites for Acl4 and the nuclear transport factor Kap104, facilitating its continuous protection from the cellular degradation machinery. Thus, Acl4 serves a dual function to facilitate nuclear import and simultaneously protect unassembled RpL4 from the cellular degradation machinery. Acl4 is a dedicated assembly chaperone for ribosomal protein RpL4 that recognizes RpL4 in the cytoplasm to facilitate its nuclear import. Here the authors reveal the mechanism whereby Acl4 recognizes RpL4 and functions to protect it from Tom1-mediated degradation until RpL4 incorporation into the maturing 60S pre-ribosomal subunit.
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18
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Johnson MC, Ghalei H, Doxtader KA, Karbstein K, Stroupe ME. Structural Heterogeneity in Pre-40S Ribosomes. Structure 2017; 25:329-340. [PMID: 28111018 DOI: 10.1016/j.str.2016.12.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/07/2016] [Accepted: 12/21/2016] [Indexed: 11/24/2022]
Abstract
Late-stage 40S ribosome assembly is a highly regulated dynamic process that occurs in the cytoplasm, alongside the full translation machinery. Seven assembly factors (AFs) regulate and facilitate maturation, but the mechanisms through which they work remain undetermined. Here, we present a series of structures of the immature small subunit (pre-40S) determined by three-dimensional (3D) cryoelectron microscopy with 3D sorting to assess the molecule's heterogeneity. These structures demonstrate an extensive structural heterogeneity of interface AFs that likely regulates subunit joining during 40S maturation. We also present structural models for the beak and the platform, two regions where the low resolution of previous studies did not allow for localization of AFs and the rRNA, respectively. These models are supported by biochemical analyses using point variants and suggest that maturation of the 18S 3' end is regulated by dissociation of the AF Dim1 from the subunit interface, consistent with previous biochemical analyses.
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Affiliation(s)
- Matthew C Johnson
- Department of Biological Science, Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA
| | - Homa Ghalei
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katelyn A Doxtader
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katrin Karbstein
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - M Elizabeth Stroupe
- Department of Biological Science, Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA.
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19
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Ting YH, Lu TJ, Johnson AW, Shie JT, Chen BR, Kumar S S, Lo KY. Bcp1 Is the Nuclear Chaperone of Rpl23 in Saccharomyces cerevisiae. J Biol Chem 2016; 292:585-596. [PMID: 27913624 DOI: 10.1074/jbc.m116.747634] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 11/21/2016] [Indexed: 12/18/2022] Open
Abstract
Eukaryotic ribosomes are composed of rRNAs and ribosomal proteins. Ribosomal proteins are translated in the cytoplasm and imported into the nucleus for assembly with the rRNAs. It has been shown that chaperones or karyopherins responsible for import can maintain the stability of ribosomal proteins by neutralizing unfavorable positive charges and thus facilitate their transports. Among 79 ribosomal proteins in yeast, only a few are identified with specific chaperones. Besides the classic role in maintaining protein stability, chaperones have additional roles in transport, chaperoning the assembly site, and dissociation of ribosomal proteins from karyopherins. Bcp1 has been shown to be necessary for the export of Mss4, a phosphatidylinositol 4-phosphate 5-kinase, and required for ribosome biogenesis. However, its specific function in ribosome biogenesis has not been described. Here, we show that Bcp1 dissociates Rpl23 from the karyopherins and associates with Rpl23 afterward. Loss of Bcp1 causes instability of Rpl23 and deficiency of 60S subunits. In summary, Bcp1 is a novel 60S biogenesis factor via chaperoning Rpl23 in the nucleus.
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Affiliation(s)
- Ya-Han Ting
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Ting-Jun Lu
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Arlen W Johnson
- the Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, and
| | - Jing-Ting Shie
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Bo-Ru Chen
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Suresh Kumar S
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan.,the Department of Medical Microbiology and Parasitology, Universiti Putra Malaysia, 43400 Selangor, Malaysia
| | - Kai-Yin Lo
- From the Department of Agricultural Chemistry, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei 10617, Taiwan,
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20
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Pillet B, Mitterer V, Kressler D, Pertschy B. Hold on to your friends: Dedicated chaperones of ribosomal proteins: Dedicated chaperones mediate the safe transfer of ribosomal proteins to their site of pre-ribosome incorporation. Bioessays 2016; 39:1-12. [PMID: 27859409 DOI: 10.1002/bies.201600153] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Eukaryotic ribosomes are assembled from their components, the ribosomal RNAs and ribosomal proteins, in a tremendously complex, multi-step process, which primarily takes place in the nuclear compartment. Therefore, most ribosomal proteins have to travel from the cytoplasm to their incorporation site on pre-ribosomes within the nucleus. However, due to their particular characteristics, such as a highly basic amino acid composition and the presence of unstructured extensions, ribosomal proteins are especially prone to aggregation and degradation in their unassembled state, hence specific mechanisms must operate to ensure their safe delivery. Recent studies have uncovered a group of proteins, termed dedicated chaperones, specialized in accompanying and guarding individual ribosomal proteins. In this essay, we review how these dedicated chaperones utilize different folds to interact with their ribosomal protein clients and how they ensure their soluble expression and interconnect their intracellular transport with their efficient assembly into pre-ribosomes.
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Affiliation(s)
- Benjamin Pillet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Valentin Mitterer
- Institut für Molekulare Biowissenschaften, Universität Graz, Graz, Austria
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Brigitte Pertschy
- Institut für Molekulare Biowissenschaften, Universität Graz, Graz, Austria
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21
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Nuclear import of dimerized ribosomal protein Rps3 in complex with its chaperone Yar1. Sci Rep 2016; 6:36714. [PMID: 27819319 PMCID: PMC5098186 DOI: 10.1038/srep36714] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/19/2016] [Indexed: 11/08/2022] Open
Abstract
After their cytoplasmic synthesis, ribosomal proteins need to be transported into the nucleus, where they assemble with ribosomal RNA into pre-ribosomal particles. Due to their physicochemical properties, they need protection from aggregation on this path. Newly synthesized ribosomal protein Rps3 forms a dimer that is associated with one molecule of its specific chaperone Yar1. Here we report that redundant pathways contribute to the nuclear import of Rps3, with the classical importin α/β pathway (Kap60/Kap95 in yeast) constituting a main import route. The Kap60/Kap95 heterodimer mediates efficient nuclear import of Rps3 by recognition of an N-terminal monopartite nuclear localization signal (NLS). This Rps3-NLS is located directly adjacent to the Yar1-binding site and, upon binding of Kap60 to Rps3, Yar1 is displaced from the ribosomal protein in vitro. While Yar1 does not directly interact with Kap60 in vitro, affinity purifications of Yar1 and Rps3, however, revealed that Kap60 is present in the Rps3/Yar1 complex in vivo. Indeed we could reconstitute such a protein complex containing Rps3 and both Yar1 and Kap60 in vitro. Our data suggest that binding of Yar1 to one N-domain and binding of Kap60 to the second N-domain of dimerized Rps3 orchestrates import and protection of the ribosomal protein.
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22
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Larburu N, Montellese C, O'Donohue MF, Kutay U, Gleizes PE, Plisson-Chastang C. Structure of a human pre-40S particle points to a role for RACK1 in the final steps of 18S rRNA processing. Nucleic Acids Res 2016; 44:8465-78. [PMID: 27530427 PMCID: PMC5041492 DOI: 10.1093/nar/gkw714] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/28/2016] [Accepted: 08/06/2016] [Indexed: 01/24/2023] Open
Abstract
Synthesis of ribosomal subunits in eukaryotes is a complex and tightly regulated process that has been mostly characterized in yeast. The discovery of a growing number of diseases linked to defects in ribosome biogenesis calls for a deeper understanding of these mechanisms and of the specificities of human ribosome maturation. We present the 19 Å resolution cryo-EM reconstruction of a cytoplasmic precursor to the human small ribosomal subunit, purified by using the tagged ribosome biogenesis factor LTV1 as bait. Compared to yeast pre-40S particles, this first three-dimensional structure of a human 40S subunit precursor shows noticeable differences with respect to the position of ribosome biogenesis factors and uncovers the early deposition of the ribosomal protein RACK1 during subunit maturation. Consistently, RACK1 is required for efficient processing of the 18S rRNA 3'-end, which might be related to its role in translation initiation. This first structural analysis of a human pre-ribosomal particle sets the grounds for high-resolution studies of conformational transitions accompanying ribosomal subunit maturation.
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MESH Headings
- Conserved Sequence
- Cryoelectron Microscopy
- Cytoplasm/metabolism
- GTP-Binding Proteins/metabolism
- HEK293 Cells
- HeLa Cells
- Humans
- Models, Molecular
- Neoplasm Proteins/metabolism
- Organelle Biogenesis
- Protein Binding
- RNA Processing, Post-Transcriptional/genetics
- RNA, Ribosomal, 18S/genetics
- Receptors for Activated C Kinase
- Receptors, Cell Surface/metabolism
- Ribosomal Proteins/metabolism
- Ribosome Subunits, Small, Eukaryotic/chemistry
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/ultrastructure
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- Natacha Larburu
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | | | - Marie-Françoise O'Donohue
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Ulrike Kutay
- Institut für Biochemie, ETH Zürich, CH-8093 Zurich, Switzerland
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
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23
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Yang YT, Ting YH, Liang KJ, Lo KY. The Roles of Puf6 and Loc1 in 60S Biogenesis Are Interdependent, and Both Are Required for Efficient Accommodation of Rpl43. J Biol Chem 2016; 291:19312-23. [PMID: 27458021 DOI: 10.1074/jbc.m116.732800] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Indexed: 12/22/2022] Open
Abstract
Puf6 and Loc1 have two important functional roles in the cells, asymmetric mRNA distribution and ribosome biogenesis. Puf6 and Loc1 are localized predominantly in the nucleolus. They bind ASH1 mRNA, repress its translation, and facilitate the transport to the daughter cells. Asymmetric mRNA distribution is important for cell differentiation. Besides their roles in mRNA localization, Puf6 and Loc1 have been shown to be involved in 60S biogenesis. In puf6Δ or loc1Δ cells, pre-rRNA processing and 60S export are impaired and 60S subunits are underaccumulated. The functional studies of Puf6 and Loc1 have been focused on ASH1 mRNA pathway, but their roles in 60S biogenesis are still not clear. In this study, we found that Puf6 and Loc1 interact directly with each other and both proteins interact with the ribosomal protein Rpl43 (L43e). Notably, the roles of Puf6 and Loc1 in 60S biogenesis are interdependent, and both are required for efficient accommodation of Rpl43. Loc1 is further required to maintain the protein level of Rpl43. Additionally, the recruitment of Rpl43 is required for the release of Puf6 and Loc1. We propose that Puf6 and Loc1 facilitate Rpl43 loading and are sequentially released from 60S after incorporation of Rpl43 into ribosomes in yeast.
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Affiliation(s)
- Yi-Ting Yang
- From the Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Ya-Han Ting
- From the Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kei-Jen Liang
- From the Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kai-Yin Lo
- From the Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
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24
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Mitterer V, Murat G, Réty S, Blaud M, Delbos L, Stanborough T, Bergler H, Leulliot N, Kressler D, Pertschy B. Sequential domain assembly of ribosomal protein S3 drives 40S subunit maturation. Nat Commun 2016; 7:10336. [PMID: 26831757 PMCID: PMC4740875 DOI: 10.1038/ncomms10336] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 11/29/2015] [Indexed: 11/25/2022] Open
Abstract
Eukaryotic ribosomes assemble by association of ribosomal RNA with ribosomal proteins into nuclear precursor particles, which undergo a complex maturation pathway coordinated by non-ribosomal assembly factors. Here, we provide functional insights into how successive structural re-arrangements in ribosomal protein S3 promote maturation of the 40S ribosomal subunit. We show that S3 dimerizes and is imported into the nucleus with its N-domain in a rotated conformation and associated with the chaperone Yar1. Initial assembly of S3 with 40S precursors occurs via its C-domain, while the N-domain protrudes from the 40S surface. Yar1 is replaced by the assembly factor Ltv1, thereby fixing the S3 N-domain in the rotated orientation and preventing its 40S association. Finally, Ltv1 release, triggered by phosphorylation, and flipping of the S3 N-domain into its final position results in the stable integration of S3. Such a stepwise assembly may represent a new paradigm for the incorporation of ribosomal proteins. Ribosome biogenesis involves the hierarchical assembly of several proteins and RNA components. Here the authors describe a mechanism for ribosomal protein S3 incorporation into 40S ribosomal subunits that involves S3 dimerization and stepwise incorporation of two distinct S3 interaction domains coupled to release of ribosomal maturation factors.
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Affiliation(s)
- Valentin Mitterer
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Stéphane Réty
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Magali Blaud
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Lila Delbos
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Tamsyn Stanborough
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Helmut Bergler
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Nicolas Leulliot
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Brigitte Pertschy
- Institut für Molekulare Biowissenschaften, Universität Graz, Humboldtstrasse 50, 8010 Graz, Austria
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25
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Pillet B, García-Gómez JJ, Pausch P, Falquet L, Bange G, de la Cruz J, Kressler D. The Dedicated Chaperone Acl4 Escorts Ribosomal Protein Rpl4 to Its Nuclear Pre-60S Assembly Site. PLoS Genet 2015; 11:e1005565. [PMID: 26447800 PMCID: PMC4598080 DOI: 10.1371/journal.pgen.1005565] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/11/2015] [Indexed: 11/19/2022] Open
Abstract
Ribosomes are the highly complex macromolecular assemblies dedicated to the synthesis of all cellular proteins from mRNA templates. The main principles underlying the making of ribosomes are conserved across eukaryotic organisms and this process has been studied in most detail in the yeast Saccharomyces cerevisiae. Yeast ribosomes are composed of four ribosomal RNAs (rRNAs) and 79 ribosomal proteins (r-proteins). Most r-proteins need to be transported from the cytoplasm to the nucleus where they get incorporated into the evolving pre-ribosomal particles. Due to the high abundance and difficult physicochemical properties of r-proteins, their correct folding and fail-safe targeting to the assembly site depends largely on general, as well as highly specialized, chaperone and transport systems. Many r-proteins contain universally conserved or eukaryote-specific internal loops and/or terminal extensions, which were shown to mediate their nuclear targeting and association with dedicated chaperones in a growing number of cases. The 60S r-protein Rpl4 is particularly interesting since it harbours a conserved long internal loop and a prominent C-terminal eukaryote-specific extension. Here we show that both the long internal loop and the C-terminal eukaryote-specific extension are strictly required for the functionality of Rpl4. While Rpl4 contains at least five distinct nuclear localization signals (NLS), the C-terminal part of the long internal loop associates with a specific binding partner, termed Acl4. Absence of Acl4 confers a severe slow-growth phenotype and a deficiency in the production of 60S subunits. Genetic and biochemical evidence indicates that Acl4 can be considered as a dedicated chaperone of Rpl4. Notably, Acl4 localizes to both the cytoplasm and nucleus and it has the capacity to capture nascent Rpl4 in a co-translational manner. Taken together, our findings indicate that the dedicated chaperone Acl4 accompanies Rpl4 from the cytoplasm to its pre-60S assembly site in the nucleus.
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Affiliation(s)
- Benjamin Pillet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Juan J. García-Gómez
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Patrick Pausch
- LOEWE Center for Synthetic Microbiology and Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Laurent Falquet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
- Swiss Institute of Bioinformatics, University of Fribourg, Fribourg, Switzerland
| | - Gert Bange
- LOEWE Center for Synthetic Microbiology and Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail:
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26
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Pausch P, Singh U, Ahmed YL, Pillet B, Murat G, Altegoer F, Stier G, Thoms M, Hurt E, Sinning I, Bange G, Kressler D. Co-translational capturing of nascent ribosomal proteins by their dedicated chaperones. Nat Commun 2015; 6:7494. [PMID: 26112308 PMCID: PMC4491177 DOI: 10.1038/ncomms8494] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/14/2015] [Indexed: 12/11/2022] Open
Abstract
Exponentially growing yeast cells produce every minute >160,000 ribosomal proteins. Owing to their difficult physicochemical properties, the synthesis of assembly-competent ribosomal proteins represents a major challenge. Recent evidence highlights that dedicated chaperone proteins recognize the N-terminal regions of ribosomal proteins and promote their soluble expression and delivery to the assembly site. Here we explore the intuitive possibility that ribosomal proteins are captured by dedicated chaperones in a co-translational manner. Affinity purification of four chaperones (Rrb1, Syo1, Sqt1 and Yar1) selectively enriched the mRNAs encoding their specific ribosomal protein clients (Rpl3, Rpl5, Rpl10 and Rps3). X-ray crystallography reveals how the N-terminal, rRNA-binding residues of Rpl10 are shielded by Sqt1's WD-repeat β-propeller, providing mechanistic insight into the incorporation of Rpl10 into pre-60S subunits. Co-translational capturing of nascent ribosomal proteins by dedicated chaperones constitutes an elegant mechanism to prevent unspecific interactions and aggregation of ribosomal proteins on their road to incorporation. The synthesis of ribosomes requires the orderly assembly of many proteins and large RNA molecules, a process that involves several assembly factors. Here the authors show that dedicated chaperones capture the N termini of specific nascent ribosomal proteins to promote folding and assembly into maturing ribosomes.
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Affiliation(s)
- Patrick Pausch
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße, Marburg D-35043, Germany
| | - Ujjwala Singh
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
| | - Yasar Luqman Ahmed
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Benjamin Pillet
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
| | - Guillaume Murat
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
| | - Florian Altegoer
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße, Marburg D-35043, Germany
| | - Gunter Stier
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Matthias Thoms
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, Heidelberg D-61920, Germany
| | - Gert Bange
- LOEWE Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße, Marburg D-35043, Germany
| | - Dieter Kressler
- Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, Fribourg CH-1700, Switzerland
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27
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Stelter P, Huber FM, Kunze R, Flemming D, Hoelz A, Hurt E. Coordinated Ribosomal L4 Protein Assembly into the Pre-Ribosome Is Regulated by Its Eukaryote-Specific Extension. Mol Cell 2015; 58:854-62. [PMID: 25936803 DOI: 10.1016/j.molcel.2015.03.029] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/06/2015] [Accepted: 03/23/2015] [Indexed: 02/06/2023]
Abstract
Eukaryotic ribosome biogenesis requires nuclear import and hierarchical incorporation of ∼80 ribosomal proteins (RPs) into the ribosomal RNA core. In contrast to prokaryotes, many eukaryotic RPs possess long extensions that interdigitate in the mature ribosome. RpL4 is a prime example, with an ∼80-residue-long surface extension of unknown function. Here, we identify assembly chaperone Acl4 that initially binds the universally conserved internal loop of newly synthesized RpL4 via its superhelical TPR domain, thereby restricting RpL4 loop insertion at its cognate nascent rRNA site. RpL4 release from Acl4 is orchestrated with pre-ribosome assembly, during which the eukaryote-specific RpL4 extension makes several distinct interactions with the 60S surface, including a co-evolved site on neighboring RpL18. Consequently, mutational inactivation of this contact site, on either RpL4 or RpL18, impairs RpL4-Acl4 disassembly and RpL4 pre-ribosome incorporation. We propose that hierarchical ribosome assembly can be achieved by eukaryotic RP extensions and dedicated assembly chaperones.
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Affiliation(s)
- Philipp Stelter
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Ferdinand M Huber
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ruth Kunze
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Dirk Flemming
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
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28
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Abstract
The proteome of cells is synthesized by ribosomes, complex ribonucleoproteins that in eukaryotes contain 79-80 proteins and four ribosomal RNAs (rRNAs) more than 5,400 nucleotides long. How these molecules assemble together and how their assembly is regulated in concert with the growth and proliferation of cells remain important unanswered questions. Here, we review recently emerging principles to understand how eukaryotic ribosomal proteins drive ribosome assembly in vivo. Most ribosomal proteins assemble with rRNA cotranscriptionally; their association with nascent particles is strengthened as assembly proceeds. Each subunit is assembled hierarchically by sequential stabilization of their subdomains. The active sites of both subunits are constructed last, perhaps to prevent premature engagement of immature ribosomes with active subunits. Late-assembly intermediates undergo quality-control checks for proper function. Mutations in ribosomal proteins that affect mostly late steps lead to ribosomopathies, diseases that include a spectrum of cell type-specific disorders that often transition from hypoproliferative to hyperproliferative growth.
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Affiliation(s)
- Jesus de la Cruz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocio/CSIC/Universidad de Sevilla, E-41013 Sevilla, Spain
- Departamento de Genetica, Universidad de Sevilla, E-41013 Sevilla, Spain
| | - Katrin Karbstein
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida 33458
| | - John L Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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29
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Merwin JR, Bogar LB, Poggi SB, Fitch RM, Johnson AW, Lycan DE. Genetic analysis of the ribosome biogenesis factor Ltv1 of Saccharomyces cerevisiae. Genetics 2014; 198:1071-85. [PMID: 25213169 PMCID: PMC4224153 DOI: 10.1534/genetics.114.168294] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/04/2014] [Indexed: 01/24/2023] Open
Abstract
Ribosome biogenesis has been studied extensively in the yeast Saccharomyces cerevisiae. Yeast Ltv1 is a conserved 40S-associated biogenesis factor that has been proposed to function in small subunit nuclear export. Here we show that Ltv1 has a canonical leucine-rich nuclear export signal (NES) at its extreme C terminus that is both necessary for Crm1 interaction and Ltv1 export. The C terminus of Ltv1 can substitute for the NES in the 60S-export adapter Nmd3, demonstrating that it is a functional NES. Overexpression of an Ltv1 lacking its NES (Ltv1∆C13) was strongly dominant negative and resulted in the nuclear accumulation of RpS3-GFP; however, export of the pre-40S was not affected. In addition, expression of endogenous levels of Ltv1∆C protein complemented both the slow-growth phenotype and the 40S biogenesis defect of an ltv1 deletion mutant. Thus, if Ltv1 is a nuclear export adapter for the pre-40S subunit, its function must be fully redundant with additional export factors. The dominant negative phenotype of Ltv1∆NES overexpression was suppressed by co-overexpressing RpS3 and its chaperone, Yar1, or by deletion of the RpS3-binding site in Ltv1∆NES, suggesting that titration of RpS3 by Ltv1∆NES is deleterious in yeast. The dominant-negative phenotype did not correlate with a decrease in 40S levels but rather with a reduction in the polysome-to-monosome ratio, indicating reduced rates of translation. We suggest that titration of RpS3 by excess nuclear Ltv1 interferes with 40S function or with a nonribosomal function of RpS3.
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Affiliation(s)
- Jason R Merwin
- Biochemistry and Molecular Biology Program, Lewis & Clark College, Portland, Oregon 97219
| | - Lucien B Bogar
- Biochemistry and Molecular Biology Program, Lewis & Clark College, Portland, Oregon 97219
| | - Sarah B Poggi
- Biochemistry and Molecular Biology Program, Lewis & Clark College, Portland, Oregon 97219
| | - Rebecca M Fitch
- Biochemistry and Molecular Biology Program, Lewis & Clark College, Portland, Oregon 97219
| | - Arlen W Johnson
- Department of Molecular Biosciences, University of Texas, Austin, Texas 78712
| | - Deborah E Lycan
- Biochemistry and Molecular Biology Program, Lewis & Clark College, Portland, Oregon 97219
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30
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Extra-Ribosomal Functions of the Ribosomal Protein, RPS3 as Predicted by In Silico Analysis. BORNEO JOURNAL OF RESOURCE SCIENCE AND TECHNOLOGY 1970. [DOI: 10.33736/bjrst.236.2014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Products of ribosomal protein (RP) genes have been found to play extra-ribosomal roles that range from DNA repair to RNA splicing. Their association with congenital disorders or cancers has also been widely documented. However, the relatively large number of different RPs, each with perhaps unique biological roles, has compounded the comprehensive elucidation of the physiological functions of each RPs. Experimental functional studies on the many and variegated RPs are labour intensive, time-consuming and costly. Moreover, experimental studies unguided by theoretically insights entail inaccurate results. Therefore, knowledge on the actual roles of these proteins remains largely undefined. A valid alternative is the use of bioinformatics resources to computationally predict functional roles of these biomolecules. Findings from such in silico studies of the RPS3 are reported herein. We reveal an array of possible extra-ribosomal functions that includes regulation of transcription (including via NF-κB-mediated, POK-induced and DNA-dependent), regulation of p53 activities and its stabilisation, inflammatory immune response, modulation of nNOS activities, and anti-oxidative capabilities. Our findings provide computational prediction of de novo extra-ribosomal functions of RPS3. These results will enhance the theoretical basis for designing future experimental studies on elucidating its definitive physiological roles.
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