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Arimura Y, Konishi HA, Funabiki H. MagIC-Cryo-EM: Structural determination on magnetic beads for scarce macromolecules in heterogeneous samples. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.21.576499. [PMID: 38328033 PMCID: PMC10849486 DOI: 10.1101/2024.01.21.576499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Cryo-EM single-particle analyses typically require target macromolecule concentration at 0.05~5.0 mg/ml, which is often difficult to achieve. Here, we devise Magnetic Isolation and Concentration (MagIC)-cryo-EM, a technique enabling direct structural analysis of targets captured on magnetic beads, thereby reducing the targets' concentration requirement to < 0.0005 mg/ml. Adapting MagIC-cryo-EM to a Chromatin Immunoprecipitation protocol, we characterized structural variations of the linker histone H1.8-associated nucleosomes that were isolated from interphase and metaphase chromosomes in Xenopus egg extract. Combining Duplicated Selection To Exclude Rubbish particles (DuSTER), a particle curation method that removes low signal-to-noise ratio particles, we also resolved the 3D cryo-EM structures of H1.8-bound nucleoplasmin NPM2 isolated from interphase chromosomes and revealed distinct open and closed structural variants. Our study demonstrates the utility of MagIC-cryo-EM for structural analysis of scarce macromolecules in heterogeneous samples and provides structural insights into the cell cycle-regulation of H1.8 association to nucleosomes.
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Affiliation(s)
- Yasuhiro Arimura
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065
- Current address: Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA, 98109-1024
| | - Hide A Konishi
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065
| | - Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065
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2
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Hernandez-Huertas L, Moreno-Sanchez I, Crespo-Cuadrado J, Vargas-Baco A, da Silva Pescador G, Santos-Pereira JM, Bazzini AA, Moreno-Mateos MA. CRISPR-RfxCas13d screening uncovers Bckdk as a post-translational regulator of the maternal-to-zygotic transition in teleosts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595167. [PMID: 38826327 PMCID: PMC11142190 DOI: 10.1101/2024.05.22.595167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The Maternal-to-Zygotic transition (MZT) is a reprograming process encompassing zygotic genome activation (ZGA) and the clearance of maternally-provided mRNAs. While some factors regulating MZT have been identified, there are thousands of maternal RNAs whose function has not been ascribed yet. Here, we have performed a proof-of-principle CRISPR-RfxCas13d maternal screening targeting mRNAs encoding protein kinases and phosphatases in zebrafish and identified Bckdk as a novel post-translational regulator of MZT. Bckdk mRNA knockdown caused epiboly defects, ZGA deregulation, H3K27ac reduction and a partial impairment of miR-430 processing. Phospho-proteomic analysis revealed that Phf10/Baf45a, a chromatin remodeling factor, is less phosphorylated upon Bckdk depletion. Further, phf10 mRNA knockdown also altered ZGA and Phf10 constitutively phosphorylated rescued the developmental defects observed after bckdk mRNA depletion. Altogether, our results demonstrate the competence of CRISPR-RfxCas13d screenings to uncover new regulators of early vertebrate development and shed light on the post-translational control of MZT mediated by protein phosphorylation.
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Affiliation(s)
- Luis Hernandez-Huertas
- Andalusian Center for Developmental Biology (CABD), Pablo de Olavide University/CSIC/Junta de Andalucía, Ctra. Utrera Km.1, 41013, Seville, Spain
- Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Ctra. Utrera Km.1, 41013, Seville, Spain
| | - Ismael Moreno-Sanchez
- Andalusian Center for Developmental Biology (CABD), Pablo de Olavide University/CSIC/Junta de Andalucía, Ctra. Utrera Km.1, 41013, Seville, Spain
- Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Ctra. Utrera Km.1, 41013, Seville, Spain
| | - Jesús Crespo-Cuadrado
- Andalusian Center for Developmental Biology (CABD), Pablo de Olavide University/CSIC/Junta de Andalucía, Ctra. Utrera Km.1, 41013, Seville, Spain
| | - Ana Vargas-Baco
- Andalusian Center for Developmental Biology (CABD), Pablo de Olavide University/CSIC/Junta de Andalucía, Ctra. Utrera Km.1, 41013, Seville, Spain
- Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Ctra. Utrera Km.1, 41013, Seville, Spain
| | | | - José M. Santos-Pereira
- Andalusian Center for Developmental Biology (CABD), Pablo de Olavide University/CSIC/Junta de Andalucía, Ctra. Utrera Km.1, 41013, Seville, Spain
| | - Ariel A. Bazzini
- Stowers Institute for Medical Research, 1000 E 50th St, Kansas City, MO 64110, USA
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, USA
| | - Miguel A. Moreno-Mateos
- Andalusian Center for Developmental Biology (CABD), Pablo de Olavide University/CSIC/Junta de Andalucía, Ctra. Utrera Km.1, 41013, Seville, Spain
- Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Ctra. Utrera Km.1, 41013, Seville, Spain
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3
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Helena-Bueno K, Chan LI, Melnikov SV. Rippling life on a dormant planet: hibernation of ribosomes, RNA polymerases, and other essential enzymes. Front Microbiol 2024; 15:1386179. [PMID: 38770025 PMCID: PMC11102965 DOI: 10.3389/fmicb.2024.1386179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 03/21/2024] [Indexed: 05/22/2024] Open
Abstract
Throughout the tree of life, cells and organisms enter states of dormancy or hibernation as a key feature of their biology: from a bacterium arresting its growth in response to starvation, to a plant seed anticipating placement in fertile ground, to a human oocyte poised for fertilization to create a new life. Recent research shows that when cells hibernate, many of their essential enzymes hibernate too: they disengage from their substrates and associate with a specialized group of proteins known as hibernation factors. Here, we summarize how hibernation factors protect essential cellular enzymes from undesired activity or irreparable damage in hibernating cells. We show how molecular hibernation, once viewed as rare and exclusive to certain molecules like ribosomes, is in fact a widespread property of biological molecules that is required for the sustained persistence of life on Earth.
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Affiliation(s)
| | | | - Sergey V. Melnikov
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
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4
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Lorenzo-Orts L, Pauli A. The molecular mechanisms underpinning maternal mRNA dormancy. Biochem Soc Trans 2024; 52:861-871. [PMID: 38477334 PMCID: PMC11088918 DOI: 10.1042/bst20231122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/28/2024] [Accepted: 03/04/2024] [Indexed: 03/14/2024]
Abstract
A large number of mRNAs of maternal origin are produced during oogenesis and deposited in the oocyte. Since transcription stops at the onset of meiosis during oogenesis and does not resume until later in embryogenesis, maternal mRNAs are the only templates for protein synthesis during this period. To ensure that a protein is made in the right place at the right time, the translation of maternal mRNAs must be activated at a specific stage of development. Here we summarize our current understanding of the sophisticated mechanisms that contribute to the temporal repression of maternal mRNAs, termed maternal mRNA dormancy. We discuss mechanisms at the level of the RNA itself, such as the regulation of polyadenine tail length and RNA modifications, as well as at the level of RNA-binding proteins, which often block the assembly of translation initiation complexes at the 5' end of an mRNA or recruit mRNAs to specific subcellular compartments. We also review microRNAs and other mechanisms that contribute to repressing translation, such as ribosome dormancy. Importantly, the mechanisms responsible for mRNA dormancy during the oocyte-to-embryo transition are also relevant to cellular quiescence in other biological contexts.
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Affiliation(s)
- Laura Lorenzo-Orts
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Andrea Pauli
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
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5
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Du M, Li X, Dong W, Zeng F. Implication of Stm1 in the protection of eIF5A, eEF2 and tRNA through dormant ribosomes. Front Mol Biosci 2024; 11:1395220. [PMID: 38698775 PMCID: PMC11063288 DOI: 10.3389/fmolb.2024.1395220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 04/09/2024] [Indexed: 05/05/2024] Open
Abstract
Background: Dormant ribosomes are typically associated with preservation factors to protect themselves from degradation under stress conditions. Stm1/SERBP1 is one such protein that anchors the 40S and 60S subunits together. Several proteins and tRNAs bind to this complex as well, yet the molecular mechanisms remain unclear. Methods: Here, we reported the cryo-EM structures of five newly identified Stm1/SERBP1-bound ribosomes. Results: These structures highlighted that eIF5A, eEF2, and tRNA might bind to dormant ribosomes under stress to avoid their own degradation, thus facilitating protein synthesis upon the restoration of growth conditions. In addition, Ribo-seq data analysis reflected the upregulation of nutrient, metabolism, and external-stimulus-related pathways in the ∆stm1 strain, suggesting possible regulatory roles of Stm1. Discussion: The knowledge generated from the present work will facilitate in better understanding the molecular mechanism of dormant ribosomes.
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Affiliation(s)
- Mengtan Du
- Department of Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, China
| | - Xin Li
- Department of Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, China
| | - Wanlin Dong
- Department of Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, China
| | - Fuxing Zeng
- Department of Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, China
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6
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Yang G, Xin Q, Dean J. Degradation and translation of maternal mRNA for embryogenesis. Trends Genet 2024; 40:238-249. [PMID: 38262796 DOI: 10.1016/j.tig.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/23/2023] [Accepted: 12/29/2023] [Indexed: 01/25/2024]
Abstract
Maternal mRNAs accumulate during egg growth and must be judiciously degraded or translated to ensure successful development of mammalian embryos. In this review we integrate recent investigations into pathways controlling rapid degradation of maternal mRNAs during the maternal-to-zygotic transition. Degradation is not indiscriminate, and some mRNAs are selectively protected and rapidly translated after fertilization for reprogramming the zygotic genome during early embryogenesis. Oocyte specific cofactors and pathways have been illustrated to control different futures of maternal mRNAs. We discuss mechanisms that control the fate of maternal mRNAs during late oogenesis and after fertilization. Issues to be resolved in current maternal mRNA research are described, and future research directions are proposed.
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Affiliation(s)
- Guanghui Yang
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Qiliang Xin
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jurrien Dean
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
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Lorenzo-Orts L, Strobl M, Steinmetz B, Leesch F, Pribitzer C, Roehsner J, Schutzbier M, Dürnberger G, Pauli A. eIF4E1b is a non-canonical eIF4E protecting maternal dormant mRNAs. EMBO Rep 2024; 25:404-427. [PMID: 38177902 PMCID: PMC10883267 DOI: 10.1038/s44319-023-00006-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 10/31/2023] [Accepted: 11/08/2023] [Indexed: 01/06/2024] Open
Abstract
Maternal mRNAs are essential for protein synthesis during oogenesis and early embryogenesis. To adapt translation to specific needs during development, maternal mRNAs are translationally repressed by shortening the polyA tails. While mRNA deadenylation is associated with decapping and degradation in somatic cells, maternal mRNAs with short polyA tails are stable. Here we report that the germline-specific eIF4E paralog, eIF4E1b, is essential for zebrafish oogenesis. eIF4E1b localizes to P-bodies in zebrafish embryos and binds to mRNAs with reported short or no polyA tails, including histone mRNAs. Loss of eIF4E1b results in reduced histone mRNA levels in early gonads, consistent with a role in mRNA storage. Using mouse and human eIF4E1Bs (in vitro) and zebrafish eIF4E1b (in vivo), we show that unlike canonical eIF4Es, eIF4E1b does not interact with eIF4G to initiate translation. Instead, eIF4E1b interacts with the translational repressor eIF4ENIF1, which is required for eIF4E1b localization to P-bodies. Our study is consistent with an important role of eIF4E1b in regulating mRNA dormancy and provides new insights into fundamental post-transcriptional regulatory principles governing early vertebrate development.
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Affiliation(s)
- Laura Lorenzo-Orts
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria.
| | - Marcus Strobl
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Benjamin Steinmetz
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093, Zurich, Switzerland
| | - Friederike Leesch
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Carina Pribitzer
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Josef Roehsner
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Michael Schutzbier
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Gerhard Dürnberger
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Andrea Pauli
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria.
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8
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Ugajin N, Imami K, Takada H, Ishihama Y, Chiba S, Mishima Y. Znf598-mediated Rps10/eS10 ubiquitination contributes to the ribosome ubiquitination dynamics during zebrafish development. RNA (NEW YORK, N.Y.) 2023; 29:1910-1927. [PMID: 37751929 PMCID: PMC10653392 DOI: 10.1261/rna.079633.123] [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: 02/12/2023] [Accepted: 09/05/2023] [Indexed: 09/28/2023]
Abstract
The ribosome is a translational apparatus that comprises about 80 ribosomal proteins and four rRNAs. Recent studies reported that ribosome ubiquitination is crucial for translational regulation and ribosome-associated quality control (RQC). However, little is known about the dynamics of ribosome ubiquitination under complex biological processes of multicellular organisms. To explore ribosome ubiquitination during animal development, we generated a zebrafish strain that expresses a FLAG-tagged ribosomal protein Rpl36/eL36 from its endogenous locus. We examined ribosome ubiquitination during zebrafish development by combining affinity purification of ribosomes from rpl36-FLAG zebrafish embryos with immunoblotting analysis. Our findings showed that the ubiquitination of ribosomal proteins dynamically changed as development proceeded. We also showed that during zebrafish development, the ribosome was ubiquitinated by Znf598, an E3 ubiquitin ligase that activates RQC. Ribosomal protein Rps10/eS10 was found to be a key ubiquitinated protein during development. Furthermore, we showed that Rps10/eS10 ubiquitination-site mutations reduced the overall ubiquitination pattern of the ribosome. These results demonstrate the complexity and dynamics of ribosome ubiquitination during zebrafish development.
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Affiliation(s)
- Nozomi Ugajin
- Department of Frontier Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Koshi Imami
- RIKEN Center for Integrative Medical Sciences, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiraku Takada
- Department of Frontier Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Yasushi Ishihama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shinobu Chiba
- Department of Frontier Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Yuichiro Mishima
- Department of Frontier Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
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Reimão-Pinto MM, Castillo-Hair SM, Seelig G, Schier AF. The regulatory landscape of 5' UTRs in translational control during zebrafish embryogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.23.568470. [PMID: 38045294 PMCID: PMC10690280 DOI: 10.1101/2023.11.23.568470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The 5' UTRs of mRNAs are critical for translation regulation, but their in vivo regulatory features are poorly characterized. Here, we report the regulatory landscape of 5' UTRs during early zebrafish embryogenesis using a massively parallel reporter assay of 18,154 sequences coupled to polysome profiling. We found that the 5' UTR is sufficient to confer temporal dynamics to translation initiation, and identified 86 motifs enriched in 5' UTRs with distinct ribosome recruitment capabilities. A quantitative deep learning model, DaniO5P, revealed a combined role for 5' UTR length, translation initiation site context, upstream AUGs and sequence motifs on in vivo ribosome recruitment. DaniO5P predicts the activities of 5' UTR isoforms and indicates that modulating 5' UTR length and motif grammar contributes to translation initiation dynamics. This study provides a first quantitative model of 5' UTR-based translation regulation in early vertebrate development and lays the foundation for identifying the underlying molecular effectors. Highlights In vivo MPRA systematically interrogates the regulatory potential of endogenous 5' UTRs The 5' UTR alone is sufficient to regulate the dynamics of ribosome recruitment during early embryogenesis The MPRA identifies 5' UTR cis -regulatory motifs for translation initiation control 5' UTR length, upstream AUGs and motif grammar contribute to the differential regulatory capability of 5' UTR switching isoforms.
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10
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Njenga R, Boele J, Öztürk Y, Koch HG. Coping with stress: How bacteria fine-tune protein synthesis and protein transport. J Biol Chem 2023; 299:105163. [PMID: 37586589 PMCID: PMC10502375 DOI: 10.1016/j.jbc.2023.105163] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/08/2023] [Accepted: 08/10/2023] [Indexed: 08/18/2023] Open
Abstract
Maintaining a functional proteome under different environmental conditions is challenging for every organism, in particular for unicellular organisms, such as bacteria. In order to cope with changing environments and stress conditions, bacteria depend on strictly coordinated proteostasis networks that control protein production, folding, trafficking, and degradation. Regulation of ribosome biogenesis and protein synthesis are cornerstones of this cellular adaptation in all domains of life, which is rationalized by the high energy demand of both processes and the increased resistance of translationally silent cells against internal or external poisons. Reduced protein synthesis ultimately also reduces the substrate load for protein transport systems, which are required for maintaining the periplasmic, inner, and outer membrane subproteomes. Consequences of impaired protein transport have been analyzed in several studies and generally induce a multifaceted response that includes the upregulation of chaperones and proteases and the simultaneous downregulation of protein synthesis. In contrast, generally less is known on how bacteria adjust the protein targeting and transport machineries to reduced protein synthesis, e.g., when cells encounter stress conditions or face nutrient deprivation. In the current review, which is mainly focused on studies using Escherichia coli as a model organism, we summarize basic concepts on how ribosome biogenesis and activity are regulated under stress conditions. In addition, we highlight some recent developments on how stress conditions directly impair protein targeting to the bacterial membrane. Finally, we describe mechanisms that allow bacteria to maintain the transport of stress-responsive proteins under conditions when the canonical protein targeting pathways are impaired.
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Affiliation(s)
- Robert Njenga
- Faculty of Medicine, Institute for Biochemistry and Molecular Biology, ZBMZ, Albert-Ludwigs University Freiburg, Freiburg, Germany; Faculty of Biology, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Julian Boele
- Faculty of Medicine, Institute for Biochemistry and Molecular Biology, ZBMZ, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Yavuz Öztürk
- Faculty of Medicine, Institute for Biochemistry and Molecular Biology, ZBMZ, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Hans-Georg Koch
- Faculty of Medicine, Institute for Biochemistry and Molecular Biology, ZBMZ, Albert-Ludwigs University Freiburg, Freiburg, Germany.
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Dyomin A, Galkina S, Ilina A, Gaginskaya E. Single Copies of the 5S rRNA Inserted into 45S rDNA Intergenic Spacers in the Genomes of Nototheniidae (Perciformes, Actinopterygii). Int J Mol Sci 2023; 24:ijms24087376. [PMID: 37108537 PMCID: PMC10138776 DOI: 10.3390/ijms24087376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
In the vast majority of Animalia genomes, the 5S rRNA gene repeats are located on chromosomes outside of the 45S rDNA arrays of the nucleolar organiser (NOR). We analysed the genomic databases available and found that a 5S rDNA sequence is inserted into the intergenic spacer (IGS) between the 45S rDNA repeats in ten species of the family Nototheniidae (Perciformes, Actinopterigii). We call this sequence the NOR-5S rRNA gene. Along with Testudines and Crocodilia, this is the second case of a close association between four rRNA genes within one repetitive unit in deuterostomes. In both cases, NOR-5S is oriented opposite the 45S rDNA. None of the three nucleotide substitutions compared to the canonical 5S rRNA gene influenced the 5S rRNA secondary structure. In transcriptomes of the Patagonian toothfish, we only found NOR-5S rRNA reads in ovaries and early embryos, but not in testis or somatic tissues of adults. Thus, we consider the NOR-5S gene to be a maternal-type 5S rRNA template. The colocalization of the 5S and 45S ribosomal genes appears to be essential for the equimolar production of all four rRNAs in the species that show rDNA amplification during oogenesis. Most likely, the integration of 5S and NOR rRNA genes occurred prior to Nototheniidae lineage diversification.
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Affiliation(s)
- Alexander Dyomin
- Biological Faculty, St. Petersburg State University, Universitetskaya Emb. 7/9, St. Petersburg 199034, Russia
| | - Svetlana Galkina
- Biological Faculty, St. Petersburg State University, Universitetskaya Emb. 7/9, St. Petersburg 199034, Russia
| | - Arina Ilina
- Biological Faculty, St. Petersburg State University, Universitetskaya Emb. 7/9, St. Petersburg 199034, Russia
| | - Elena Gaginskaya
- Biological Faculty, St. Petersburg State University, Universitetskaya Emb. 7/9, St. Petersburg 199034, Russia
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