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Nissley A, Penev P, Watson Z, Banfield J, Cate JD. Rare ribosomal RNA sequences from archaea stabilize the bacterial ribosome. Nucleic Acids Res 2023; 51:1880-1894. [PMID: 36660825 PMCID: PMC9976906 DOI: 10.1093/nar/gkac1273] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/15/2022] [Accepted: 12/28/2022] [Indexed: 01/21/2023] Open
Abstract
The ribosome serves as the universally conserved translator of the genetic code into proteins and supports life across diverse temperatures ranging from below freezing to above 120°C. Ribosomes are capable of functioning across this wide range of temperatures even though the catalytic site for peptide bond formation, the peptidyl transferase center, is nearly universally conserved. Here we find that Thermoproteota, a phylum of thermophilic Archaea, substitute cytidine for uridine at large subunit rRNA positions 2554 and 2555 (Escherichia coli numbering) in the A loop, immediately adjacent to the binding site for the 3'-end of A-site tRNA. We show by cryo-EM that E. coli ribosomes with uridine to cytidine mutations at these positions retain the proper fold and post-transcriptional modification of the A loop. Additionally, these mutations do not affect cellular growth, protect the large ribosomal subunit from thermal denaturation, and increase the mutational robustness of nucleotides in the peptidyl transferase center. This work identifies sequence variation across archaeal ribosomes in the peptidyl transferase center that likely confers stabilization of the ribosome at high temperatures and develops a stable mutant bacterial ribosome that can act as a scaffold for future ribosome engineering efforts.
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Affiliation(s)
- Amos J Nissley
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Petar I Penev
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Zoe L Watson
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jillian F Banfield
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA
- Environmental Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jamie H D Cate
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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2
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Timsit Y, Grégoire SP. Towards the Idea of Molecular Brains. Int J Mol Sci 2021; 22:ijms222111868. [PMID: 34769300 PMCID: PMC8584932 DOI: 10.3390/ijms222111868] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/24/2021] [Accepted: 10/28/2021] [Indexed: 02/06/2023] Open
Abstract
How can single cells without nervous systems perform complex behaviours such as habituation, associative learning and decision making, which are considered the hallmark of animals with a brain? Are there molecular systems that underlie cognitive properties equivalent to those of the brain? This review follows the development of the idea of molecular brains from Darwin’s “root brain hypothesis”, through bacterial chemotaxis, to the recent discovery of neuron-like r-protein networks in the ribosome. By combining a structural biology view with a Bayesian brain approach, this review explores the evolutionary labyrinth of information processing systems across scales. Ribosomal protein networks open a window into what were probably the earliest signalling systems to emerge before the radiation of the three kingdoms. While ribosomal networks are characterised by long-lasting interactions between their protein nodes, cell signalling networks are essentially based on transient interactions. As a corollary, while signals propagated in persistent networks may be ephemeral, networks whose interactions are transient constrain signals diffusing into the cytoplasm to be durable in time, such as post-translational modifications of proteins or second messenger synthesis. The duration and nature of the signals, in turn, implies different mechanisms for the integration of multiple signals and decision making. Evolution then reinvented networks with persistent interactions with the development of nervous systems in metazoans. Ribosomal protein networks and simple nervous systems display architectural and functional analogies whose comparison could suggest scale invariance in information processing. At the molecular level, the significant complexification of eukaryotic ribosomal protein networks is associated with a burst in the acquisition of new conserved aromatic amino acids. Knowing that aromatic residues play a critical role in allosteric receptors and channels, this observation suggests a general role of π systems and their interactions with charged amino acids in multiple signal integration and information processing. We think that these findings may provide the molecular basis for designing future computers with organic processors.
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Affiliation(s)
- Youri Timsit
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM110, 13288 Marseille, France
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/Tara GOSEE, 3 rue Michel-Ange, 75016 Paris, France
- Correspondence:
| | - Sergeant-Perthuis Grégoire
- Institut de Mathématiques de Jussieu—Paris Rive Gauche (IMJ-PRG), UMR 7586, CNRS-Université Paris Diderot, 75013 Paris, France;
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3
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Context-specific action of macrolide antibiotics on the eukaryotic ribosome. Nat Commun 2021; 12:2803. [PMID: 33990576 PMCID: PMC8121947 DOI: 10.1038/s41467-021-23068-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/14/2021] [Indexed: 01/09/2023] Open
Abstract
Macrolide antibiotics bind in the nascent peptide exit tunnel of the bacterial ribosome and prevent polymerization of specific amino acid sequences, selectively inhibiting translation of a subset of proteins. Because preventing translation of individual proteins could be beneficial for the treatment of human diseases, we asked whether macrolides, if bound to the eukaryotic ribosome, would retain their context- and protein-specific action. By introducing a single mutation in rRNA, we rendered yeast Saccharomyces cerevisiae cells sensitive to macrolides. Cryo-EM structural analysis showed that the macrolide telithromycin binds in the tunnel of the engineered eukaryotic ribosome. Genome-wide analysis of cellular translation and biochemical studies demonstrated that the drug inhibits eukaryotic translation by preferentially stalling ribosomes at distinct sequence motifs. Context-specific action markedly depends on the macrolide structure. Eliminating macrolide-arrest motifs from a protein renders its translation macrolide-tolerant. Our data illuminate the prospects of adapting macrolides for protein-selective translation inhibition in eukaryotic cells.
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4
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Abstract
To perform an accurate protein synthesis, ribosomes accomplish complex tasks involving the long-range communication between its functional centres such as the peptidyl transfer centre, the tRNA bindings sites and the peptide exit tunnel. How information is transmitted between these sites remains one of the major challenges in current ribosome research. Many experimental studies have revealed that some r-proteins play essential roles in remote communication and the possible involvement of r-protein networks in these processes have been recently proposed. Our phylogenetic, structural and mathematical study reveals that of the three kingdom's r-protein networks converged towards non-random graphs where r-proteins collectively coevolved to optimize interconnection between functional centres. The massive acquisition of conserved aromatic residues at the interfaces and along the extensions of the newly connected eukaryotic r-proteins also highlights that a strong selective pressure acts on their sequences probably for the formation of new allosteric pathways in the network.
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5
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A Structural Basis for Restricted Codon Recognition Mediated by 2-thiocytidine in tRNA Containing a Wobble Position Inosine. J Mol Biol 2020; 432:913-929. [PMID: 31945376 DOI: 10.1016/j.jmb.2019.12.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 11/25/2019] [Accepted: 12/05/2019] [Indexed: 11/20/2022]
Abstract
Three of six arginine codons (CGU, CGC, and CGA) are decoded by two Escherichia coli tRNAArg isoacceptors. The anticodon stem and loop (ASL) domains of tRNAArg1 and tRNAArg2 both contain inosine and 2-methyladenosine modifications at positions 34 (I34) and 37 (m2A37). tRNAArg1 is also modified from cytidine to 2-thiocytidine at position 32 (s2C32). The s2C32 modification is known to negate wobble codon recognition of the rare CGA codon by an unknown mechanism, while still allowing decoding of CGU and CGC. Substitution of s2C32 for C32 in the Saccharomyces cerevisiae tRNAIleIAU anticodon stem and loop domain (ASL) negates wobble decoding of its synonymous A-ending codon, suggesting that this function of s2C at position 32 is a generalizable property. X-ray crystal structures of variously modified ASLArg1ICG and ASLArg2ICG constructs bound to cognate and wobble codons on the ribosome revealed the disruption of a C32-A38 cross-loop interaction but failed to fully explain the means by which s2C32 restricts I34 wobbling. Computational studies revealed that the adoption of a spatially broad inosine-adenosine base pair at the wobble position of the codon cannot be maintained simultaneously with the canonical ASL U-turn motif. C32-A38 cross-loop interactions are required for stability of the anticodon/codon interaction in the ribosomal A-site.
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6
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Kürkçüoğlu Ö. Exploring allosteric communication in multiple states of the bacterial ribosome using residue network analysis. Turk J Biol 2018; 42:392-404. [PMID: 30930623 PMCID: PMC6438126 DOI: 10.3906/biy-1802-77] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Antibiotic resistance is one of the most important problems of our era and hence the discovery of new effective therapeutics is urgent. At this point, studying the allosteric communication pathways in the bacterial ribosome and revealing allosteric sites/residues is critical for designing new inhibitors or repurposing readily approved drugs for this enormous machine. To shed light onto molecular details of the allosteric mechanisms, here we construct residue networks of the bacterial ribosomal complex at four different states of translation by using an effective description of the intermolecular interactions. Centrality analysis of these networks highlights the functional roles of structural components and critical residues on the ribosomal complex. High betweenness scores reveal pathways of residues connecting numerous sites on the structure. Interestingly, these pathways assemble highly conserved residues, drug binding sites, and known allosterically linked regions on the same structure. This study proposes a new residue-level model to test how distant sites on the molecular machine may be linked through hub residues that are critically located on the contact topology to inherently form communication pathways. Findings also indicate intersubunit bridges B1b, B3, B5, B7, and B8 as critical targets to design novel antibiotics.
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Affiliation(s)
- Özge Kürkçüoğlu
- Department of Chemical Engineering, Faculty of Chemical-Metallurgical Engineering, İstanbul Technical University , İstanbul , Turkey
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7
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Makarova TM, Bogdanov AA. The Ribosome as an Allosterically Regulated Molecular Machine. BIOCHEMISTRY (MOSCOW) 2018. [PMID: 29523059 DOI: 10.1134/s0006297917130016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ribosome as a complex molecular machine undergoes significant conformational rearrangements during the synthesis of polypeptide chains of proteins. In this review, information obtained using various experimental methods on the internal consistency of such rearrangements is discussed. It is demonstrated that allosteric regulation involves all the main stages of the operation of the ribosome and connects functional elements remote by tens and even hundreds of angstroms. Data obtained using Förster resonance energy transfer (FRET) show that translocation is controlled in general by internal mechanisms of the ribosome, and not by the position of the ligands. Chemical probing data revealed the relationship of such remote sites as the decoding, peptidyl transferase, and GTPase centers of the ribosome. Nevertheless, despite the large amount of experimental data accumulated to date, many details and mechanisms of these phenomena are still not understood. Analysis of these data demonstrates that the development of new approaches is necessary for deciphering the mechanisms of allosteric regulation of the operation of the ribosome.
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Affiliation(s)
- T M Makarova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
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8
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Identification of potential allosteric communication pathways between functional sites of the bacterial ribosome by graph and elastic network models. Biochim Biophys Acta Gen Subj 2017; 1861:3131-3141. [PMID: 28917952 DOI: 10.1016/j.bbagen.2017.09.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Revised: 09/11/2017] [Accepted: 09/12/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND Accumulated evidence indicates that bacterial ribosome employs allostery throughout its structure for protein synthesis. The nature of the allosteric communication between remote functional sites remains unclear, but the contact topology and dynamics of residues may play role in transmission of a perturbation to distant sites. METHODS/RESULTS We employ two computationally efficient approaches - graph and elastic network modeling to gain insights about the allosteric communication in ribosome. Using graph representation of the structure, we perform k-shortest pathways analysis between peptidyl transferase center-ribosomal tunnel, decoding center-peptidyl transferase center - previously reported functional sites having allosteric communication. Detailed analysis on intact structures points to common and alternative shortest pathways preferred by different states of translation. All shortest pathways capture drug target sites and allosterically important regions. Elastic network model further reveals that residues along all pathways have the ability of quickly establishing pair-wise communication and to help the propagation of a perturbation in long-ranges during functional motions of the complex. CONCLUSIONS Contact topology and inherent dynamics of ribosome configure potential communication pathways between functional sites in different translation states. Inter-subunit bridges B2a, B3 and P-tRNA come forward for their high potential in assisting allostery during translation. Especially B3 emerges as a potential druggable site. GENERAL SIGNIFICANCE This study indicates that the ribosome topology forms a basis for allosteric communication, which can be disrupted by novel drugs to kill drug-resistant bacteria. Our computationally efficient approach not only overlaps with experimental evidence on allosteric regulation in ribosome but also proposes new druggable sites.
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9
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Gulay SP, Bista S, Varshney A, Kirmizialtin S, Sanbonmatsu KY, Dinman JD. Tracking fluctuation hotspots on the yeast ribosome through the elongation cycle. Nucleic Acids Res 2017; 45:4958-4971. [PMID: 28334755 PMCID: PMC5416885 DOI: 10.1093/nar/gkx112] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 02/06/2017] [Indexed: 11/15/2022] Open
Abstract
Chemical modification was used to quantitatively determine the flexibility of nearly the entire rRNA component of the yeast ribosome through 8 discrete stages of translational elongation, revealing novel observations at the gross and fine-scales. These include (i) the bulk transfer of energy through the intersubunit bridges from the large to the small subunit after peptidyltransfer, (ii) differences in the interaction of the sarcin ricin loop with the two elongation factors and (iii) networked information exchange pathways that may functionally facilitate intra- and intersubunit coordination, including the 5.8S rRNA. These analyses reveal hot spots of fluctuations that set the stage for large-scale conformational changes essential for translocation and enable the first molecular dynamics simulation of an 80S complex. Comprehensive datasets of rRNA base flexibilities provide a unique resource to the structural biology community that can be computationally mined to complement ongoing research toward the goal of understanding the dynamic ribosome.
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Affiliation(s)
- Suna P Gulay
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Sujal Bista
- Department of Computer Science, University of Maryland, College Park, MD 20742, USA
| | - Amitabh Varshney
- Department of Computer Science, University of Maryland, College Park, MD 20742, USA
| | - Serdal Kirmizialtin
- Chemistry Program, New York University Abu Dhabi, Abu Dhabi, UAE.,The New Mexico Consortium, Los Alamos, NM 87544, USA
| | - Karissa Y Sanbonmatsu
- The New Mexico Consortium, Los Alamos, NM 87544, USA.,Theoretical Biology and Biophysics, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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10
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Atabakhshi-Kashi M, Mohammadi M, Mirhassani R, Dabirmanesh B, Sajedi RH, Khajeh K. An alternative allosteric pathway in thermophilic methylglyoxal synthase. Int J Biol Macromol 2016; 93:526-533. [PMID: 27608544 DOI: 10.1016/j.ijbiomac.2016.09.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 08/22/2016] [Accepted: 09/05/2016] [Indexed: 01/29/2023]
Abstract
Methylglyoxal synthase (MGS) is a homohexameric enzyme responsible for converting dihydroxyacetone phosphate (DHAP) to methylglyoxal and phosphate in the methylglyoxal bypass of glycolysis. Phosphate acts as an allosteric inhibitor and strong regulator for this enzyme. Previous studies on MGS from Thermus sp. GH5 (TMGS) had indicated a pathway for transmitting the signal through Pro82, Arg97 and Val101 to the active site. The necessity of these residues for heterotropic negative cooperativity between subunits of TMGS were also proposed. In this study, it has been shown that a path via a salt bridge between Arg80 and Asp100 in the narrow dimer interface provides an alternative pathway for transmission of the allosteric inhibitory signal through subunit interfaces.
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Affiliation(s)
- Mona Atabakhshi-Kashi
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran 14115-175, Iran
| | - Malihe Mohammadi
- Department of Biology, University of Sistan and Baluchestan, Zahedan, Iran
| | - Reihaneh Mirhassani
- Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran
| | - Bahareh Dabirmanesh
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran 14115-175, Iran
| | - Reza H Sajedi
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran 14115-175, Iran
| | - Khosro Khajeh
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran 14115-175, Iran.
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11
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Kisly I, Gulay SP, Mäeorg U, Dinman JD, Remme J, Tamm T. The Functional Role of eL19 and eB12 Intersubunit Bridge in the Eukaryotic Ribosome. J Mol Biol 2016; 428:2203-16. [PMID: 27038511 DOI: 10.1016/j.jmb.2016.03.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/18/2016] [Accepted: 03/22/2016] [Indexed: 12/12/2022]
Abstract
During translation, the two eukaryotic ribosomal subunits remain associated through 17 intersubunit bridges, five of which are eukaryote specific. These are mainly localized to the peripheral regions and are believed to stabilize the structure of the ribosome. The functional importance of these bridges remains largely unknown. Here, the essentiality of the eukaryote-specific bridge eB12 has been investigated. The main component of this bridge is ribosomal protein eL19 that is composed of an N-terminal globular domain, a middle region, and a long C-terminal α-helix. The analysis of deletion mutants demonstrated that the globular domain and middle region of eL19 are essential for cell viability, most likely functioning in ribosome assembly. The eB12 bridge, formed by contacts between the C-terminal α-helix of eL19 and 18S rRNA in concert with additional stabilizing interactions involving either eS7 or uS17, is dispensable for viability. Nevertheless, eL19 mutants impaired in eB12 bridge formation displayed slow growth phenotypes, altered sensitivity/resistance to translational inhibitors, and enhanced hyperosmotic stress tolerance. Biochemical analyses determined that the eB12 bridge contributes to the stability of ribosome subunit interactions in vitro. 60S subunits containing eL19 variants defective in eB12 bridge formation failed to form 80S ribosomes regardless of Mg(2+) concentration. The reassociation of 40S and mutant 60S subunits was markedly improved in the presence of deacetylated tRNA, emphasizing the importance of tRNAs during the subunit association. We propose that the eB12 bridge plays an important role in subunit joining and in optimizing ribosome functionality.
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Affiliation(s)
- Ivan Kisly
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia
| | - Suna P Gulay
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, United States
| | - Uno Mäeorg
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, United States
| | - Jaanus Remme
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia.
| | - Tiina Tamm
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia.
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12
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Kostopoulou ON, Kouvela EC, Magoulas GE, Garnelis T, Panagoulias I, Rodi M, Papadopoulos G, Mouzaki A, Dinos GP, Papaioannou D, Kalpaxis DL. Conjugation with polyamines enhances the antibacterial and anticancer activity of chloramphenicol. Nucleic Acids Res 2014; 42:8621-34. [PMID: 24939899 PMCID: PMC4117768 DOI: 10.1093/nar/gku539] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Chloramphenicol (CAM) is a broad-spectrum antibiotic, limited to occasional only use in developed countries because of its potential toxicity. To explore the influence of polyamines on the uptake and activity of CAM into cells, a series of polyamine–CAM conjugates were synthesized. Both polyamine architecture and the position of CAM-scaffold substitution were crucial in augmenting the antibacterial and anticancer potency of the synthesized conjugates. Compounds 4 and 5, prepared by replacement of dichloro-acetyl group of CAM with succinic acid attached to N4 and N1 positions of N8,N8-dibenzylspermidine, respectively, exhibited higher activity than CAM in inhibiting the puromycin reaction in a bacterial cell-free system. Kinetic and footprinting analysis revealed that whereas the CAM-scaffold preserved its role in competing with the binding of aminoacyl-tRNA 3′-terminus to ribosomal A-site, the polyamine-tail could interfere with the rotatory motion of aminoacyl-tRNA 3′-terminus toward the P-site. Compared to CAM, compounds 4 and 5 exhibited comparable or improved antibacterial activity, particularly against CAM-resistant strains. Compound 4 also possessed enhanced toxicity against human cancer cells, and lower toxicity against healthy human cells. Thus, the designed conjugates proved to be suitable tools in investigating the ribosomal catalytic center plasticity and some of them exhibited greater efficacy than CAM itself.
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Affiliation(s)
- Ourania N Kostopoulou
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Ekaterini C Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - George E Magoulas
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Thomas Garnelis
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Ioannis Panagoulias
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, GR-26504 Patras, Greece
| | - Maria Rodi
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, GR-26504 Patras, Greece
| | - Georgios Papadopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Ploutonos 26, GR-41221 Larissa, Greece
| | - Athanasia Mouzaki
- Laboratory of Synthetic Organic Chemistry, Department of Chemistry, University of Patras, GR-26504 Patras, Greece
| | - George P Dinos
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Dionissios Papaioannou
- Division of Hematology, Department of Internal Medicine, School of Medicine, University of Patras, GR-26504 Patras, Greece
| | - Dimitrios L Kalpaxis
- Department of Biochemistry, School of Medicine, University of Patras, GR-26504 Patras, Greece
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13
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Sulima SO, Gülay SP, Anjos M, Patchett S, Meskauskas A, Johnson AW, Dinman JD. Eukaryotic rpL10 drives ribosomal rotation. Nucleic Acids Res 2013; 42:2049-63. [PMID: 24214990 PMCID: PMC3919601 DOI: 10.1093/nar/gkt1107] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Ribosomes transit between two conformational states, non-rotated and rotated, through the elongation cycle. Here, we present evidence that an internal loop in the essential yeast ribosomal protein rpL10 is a central controller of this process. Mutations in this loop promote opposing effects on the natural equilibrium between these two extreme conformational states. rRNA chemical modification analyses reveals allosteric interactions involved in coordinating intersubunit rotation originating from rpL10 in the core of the large subunit (LSU) through both subunits, linking all the functional centers of the ribosome. Mutations promoting rotational disequilibria showed catalytic, biochemical and translational fidelity defects. An rpL3 mutation promoting opposing structural and biochemical effects, suppressed an rpL10 mutant, re-establishing rotational equilibrium. The rpL10 loop is also involved in Sdo1p recruitment, suggesting that rotational status is important for ensuring late-stage maturation of the LSU, supporting a model in which pre-60S subunits undergo a ‘test drive’ before final maturation.
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Affiliation(s)
- Sergey O Sulima
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA, Section of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA and Department of Biotechnology and Microbiology, Vilnius University, Vilnius LT-03101, Lithuania
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14
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Nemoto N, Udagawa T, Chowdhury W, Kitabatake M, Shin BS, Hiraishi H, Wang S, Singh CR, Brown SJ, Ohno M, Asano K. Random mutagenesis of yeast 25S rRNA identify bases critical for 60S subunit structural integrity and function. ACTA ACUST UNITED AC 2013; 1:e26402. [PMID: 26824023 PMCID: PMC4718063 DOI: 10.4161/trla.26402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 08/08/2013] [Accepted: 09/06/2013] [Indexed: 01/28/2023]
Abstract
In yeast Saccharomyces cerevisiae, 25S rRNA makes up the major mass and shape of the 60S ribosomal subunit. During translation initiation, the 60S subunit joins the 40S initiation complex, producing the 80S initiation complex. During elongation, the 60S subunit binds the CCA-ends of aminoacyl- and peptidyl-tRNAs at the A-loop and P-loop, respectively, transferring the peptide onto the α-amino group of the aminoacyl-tRNA. To study the role of 25S rRNA in translation in vivo, we randomly mutated 25S rRNA and isolated and characterized seven point mutations that affected yeast cell growth and polysome profiles. Four of these mutations, G651A, A1435U, A1446G and A1587G, change a base involved in base triples crucial for structural integrity. Three other mutations change bases near the ribosomal surface: C2879U and U2408C alter the A-loop and P-loop, respectively, and G1735A maps near a Eukarya-specific bridge to the 40S subunit. By polysome profiling in mmslΔ mutants defective in nonfunctional 25S rRNA decay, we show that some of these mutations are defective in both the initiation and elongation phases of translation. Of the mutants characterized, C2879U displays the strongest defect in translation initiation. The ribosome transit-time assay directly shows that this mutation is also defective in peptide elongation/termination. Thus, our genetic analysis not only identifies bases critical for structural integrity of the 60S subunit, but also suggests a role for bases near the peptidyl transferase center in translation initiation.
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Affiliation(s)
- Naoki Nemoto
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
| | - Tsuyoshi Udagawa
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
| | - Wasimul Chowdhury
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
| | | | - Byung-Shik Shin
- Laboratory of Gene Regulation and Development; Eunice Kennedy Shriver NICHD; National Institutes of Health; Bethesda, MD USA
| | - Hiroyuki Hiraishi
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
| | - Suzhi Wang
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA; Arthropod Genomics Center; Division of Biology; Kansas State University; Manhattan, KS USA
| | - Chingakham Ranjit Singh
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
| | - Susan J Brown
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA; Arthropod Genomics Center; Division of Biology; Kansas State University; Manhattan, KS USA
| | - Mutsuhito Ohno
- Insititute for Virus Research; Kyoto University; Kyoto, Japan
| | - Katsura Asano
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
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15
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Ma X, Kim EJ, Kook I, Ma F, Voshall A, Moriyama E, Cerutti H. Small interfering RNA-mediated translation repression alters ribosome sensitivity to inhibition by cycloheximide in Chlamydomonas reinhardtii. THE PLANT CELL 2013; 25:985-98. [PMID: 23512853 PMCID: PMC3634701 DOI: 10.1105/tpc.113.109256] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Small RNAs (sRNAs; ∼20 to 30 nucleotides in length) play important roles in gene regulation as well as in defense responses against transposons and viruses in eukaryotes. Their biogenesis and modes of action have attracted great attention in recent years. However, many aspects of sRNA function, such as the mechanism(s) of translation repression at postinitiation steps, remain poorly characterized. In the unicellular green alga Chlamydomonas reinhardtii, sRNAs derived from genome-integrated inverted repeat transgenes, perfectly complementary to the 3' untranslated region of a target transcript, can inhibit protein synthesis without or with only minimal mRNA destabilization. Here, we report that the sRNA-repressed transcripts are not altered in their polyadenylation status and they remain associated with polyribosomes, indicating inhibition at a postinitiation step of translation. Interestingly, ribosomes associated with sRNA-repressed transcripts show reduced sensitivity to translation inhibition by some antibiotics, such as cycloheximide, both in ribosome run-off assays and in in vivo experiments. Our results suggest that sRNA-mediated repression of protein synthesis in C. reinhardtii may involve alterations to the function/structural conformation of translating ribosomes. Additionally, sRNA-mediated translation inhibition is now known to occur in a number of phylogenetically diverse eukaryotes, suggesting that this mechanism may have been a feature of an ancestral RNA interference machinery.
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16
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Wang Y, Shen JK, Schroeder SJ. Nucleotide Dynamics at the A-Site Cleft in the Peptidyltransferase Center of H. marismortui 50S Ribosomal Subunits. J Phys Chem Lett 2012; 3:1007-1010. [PMID: 26286564 DOI: 10.1021/jz3001882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Resistance mutations to antibiotics targeting rRNA can be far from the drug-binding site. Crystallography studies revealed that the antibiotic resistance mutation G2482A (G2447A in E. coli ) in Haloarcula marismortui 50S ribosomes does not directly contact the drug or introduce changes to the ribosomal structure except for losing a potassium ion coordinated to a base triple at the drug-binding site. Using molecular dynamics simulations, we tested hypotheses regarding the effects of the G2482A mutation and ion coordination on the conformational dynamics of the 50S ribosome. Simulations show that the mutation enhances conformational fluctuation at the antibiotic binding site, weakens the hydrogen-bonding network, and increases flexibility at the 50S peptidyl transferase center (PTC). Our data supports the view that distant mutations can perturb the dynamic network in the ribosomal PTC, thereby raising the entropic cost of antibiotic binding. These results underscore the importance of considering conformational dynamics in rational drug design.
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Affiliation(s)
- Yuhang Wang
- †Department of Chemistry and Biochemistry, ‡School of Chemical, Biological, and Materials Engineering, and ξDepartment of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States
| | - Jana K Shen
- †Department of Chemistry and Biochemistry, ‡School of Chemical, Biological, and Materials Engineering, and ξDepartment of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States
| | - Susan J Schroeder
- †Department of Chemistry and Biochemistry, ‡School of Chemical, Biological, and Materials Engineering, and ξDepartment of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States
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17
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40S subunit dissociation and proteasome-dependent RNA degradation in nonfunctional 25S rRNA decay. EMBO J 2012; 31:2579-89. [PMID: 22505030 DOI: 10.1038/emboj.2012.85] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Accepted: 03/15/2012] [Indexed: 11/08/2022] Open
Abstract
Eukaryotic cells have quality control systems that eliminate nonfunctional rRNAs with deleterious mutations (nonfunctional rRNA decay, NRD). We have previously reported that 25S NRD requires an E3 ubiquitin ligase complex, which is involved in ribosomal ubiquitination. However, the degradation process of nonfunctional ribosomes has remained unknown. Here, using genetic screening, we identified two ubiquitin-binding complexes, the Cdc48-Npl4-Ufd1 complex (Cdc48 complex) and the proteasome, as the factors involved in 25S NRD. We show that the nonfunctional 60S subunit is dissociated from the 40S subunit in a Cdc48 complex-dependent manner, before it is attacked by the proteasome. When we examined the nonfunctional 60S subunits that accumulated under proteasome-depleted conditions, the majority of mutant 25S rRNAs retained their full length at a single-nucleotide resolution. This indicates that the proteasome is an essential factor triggering rRNA degradation. We further showed that ribosomal ubiquitination can be stimulated solely by the suppression of the proteasome, suggesting that ubiquitin-proteasome-dependent RNA degradation occurs in broader situations, including in general rRNA turnover.
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18
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Rhodin MHJ, Dinman JD. An extensive network of information flow through the B1b/c intersubunit bridge of the yeast ribosome. PLoS One 2011; 6:e20048. [PMID: 21625514 PMCID: PMC3098278 DOI: 10.1371/journal.pone.0020048] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Accepted: 04/11/2011] [Indexed: 12/31/2022] Open
Abstract
Yeast ribosomal proteins L11 and S18 form a dynamic intersubunit interaction called the B1b/c bridge. Recent high resolution images of the ribosome have enabled targeting of specific residues in this bridge to address how distantly separated regions within the large and small subunits of the ribosome communicate with each other. Mutations were generated in the L11 side of the B1b/c bridge with a particular focus on disrupting the opposing charge motifs that have previously been proposed to be involved in subunit ratcheting. Mutants had wide-ranging effects on cellular viability and translational fidelity, with the most pronounced phenotypes corresponding to amino acid changes resulting in alterations of local charge properties. Chemical protection studies of selected mutants revealed rRNA structural changes in both the large and small subunits. In the large subunit rRNA, structural changes mapped to Helices 39, 80, 82, 83, 84, and the peptidyltransferase center. In the small subunit rRNA, structural changes were identified in helices 30 and 42, located between S18 and the decoding center. The rRNA structural changes correlated with charge-specific alterations to the L11 side of the B1b/c bridge. These analyses underscore the importance of the opposing charge mechanism in mediating B1b/c bridge interactions and suggest an extensive network of information exchange between distinct regions of the large and small subunits.
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Affiliation(s)
- Michael H. J. Rhodin
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Jonathan D. Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
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19
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Rakauskaite R, Dinman JD. Mutations of highly conserved bases in the peptidyltransferase center induce compensatory rearrangements in yeast ribosomes. RNA (NEW YORK, N.Y.) 2011; 17:855-864. [PMID: 21441349 PMCID: PMC3078735 DOI: 10.1261/rna.2593211] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 02/18/2011] [Indexed: 05/30/2023]
Abstract
Molecular dynamics simulation identified three highly conserved rRNA bases in the large subunit of the ribosome that form a three-dimensional (3D) "gate" that induces pausing of the aa-tRNA acceptor stem during accommodation into the A-site. A nearby fourth base contacting the "tryptophan finger" of yeast protein L3, which is involved in the coordinating elongation factor recruitment to the ribosome with peptidyltransfer, is also implicated in this process. To better understand the functional importance of these bases, single base substitutions as well as deletions at all four positions were constructed and expressed as the sole forms of ribosomes in yeast Saccharomyces cerevisiae. None of the mutants had strong effects on cell growth, translational fidelity, or on the interactions between ribosomes and tRNAs. However, the mutants did promote strong effects on cell growth in the presence of translational inhibitors, and differences in viability between yeast and Escherichia coli mutants at homologous positions suggest new targets for antibacterial therapeutics. Mutant ribosomes also promoted changes in 25S rRNA structure, all localized to the core of peptidyltransferase center (i.e., the proto-ribosome area). We suggest that a certain degree of structural plasticity is built into the ribosome, enabling it to ensure accurate translation of the genetic code while providing it with the flexibility to adapt and evolve.
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Affiliation(s)
- Rasa Rakauskaite
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA
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20
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Rhodin MHJ, Rakauskaitė R, Dinman JD. The central core region of yeast ribosomal protein L11 is important for subunit joining and translational fidelity. Mol Genet Genomics 2011; 285:505-16. [PMID: 21519857 DOI: 10.1007/s00438-011-0623-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 04/11/2011] [Indexed: 12/11/2022]
Abstract
Yeast ribosomal protein L11 is positioned at the intersubunit cleft of the large subunit central protuberance, forming an intersubunit bridge with the small subunit protein S18. Mutants were engineered in the central core region of L11 which interacts with Helix 84 of the 25S rRNA. Numerous mutants in this region conferred 60S subunit biogenesis defects. Specifically, many mutations of F96 and the A66D mutant promoted formation of halfmers as assayed by sucrose density ultracentrifugation. Halfmer formation was not due to deficiency in 60S subunit production, suggesting that the mutants affected subunit-joining. Chemical modification analyses indicated that the A66D mutant, but not the F96 mutants, promoted changes in 25S rRNA structure, suggesting at least two modalities for subunit joining defects. 25S rRNA structural changes were located both adjacent to A66D (in H84), and more distant (in H96-7). While none of the mutants significantly affected ribosome/tRNA binding constants, they did have strong effects on cellular growth at both high and low temperatures, in the presence of translational inhibitors, and promoted changes in translational fidelity. Two distinct mechanisms are proposed by which L11 mutants may affect subunit joining, and identification of the amino acids associated with each of these processes are presented. These findings may have implications for our understanding of multifaceted diseases such as Diamond--Blackfan anemia which have been linked in part with mutations in L11.
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Affiliation(s)
- Michael H J Rhodin
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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21
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Rhodin MHJ, Dinman JD. A flexible loop in yeast ribosomal protein L11 coordinates P-site tRNA binding. Nucleic Acids Res 2010; 38:8377-89. [PMID: 20705654 PMCID: PMC3001080 DOI: 10.1093/nar/gkq711] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 11/12/2022] Open
Abstract
High-resolution structures reveal that yeast ribosomal protein L11 and its bacterial/archael homologs called L5 contain a highly conserved, basically charged internal loop that interacts with the peptidyl-transfer RNA (tRNA) T-loop. We call this the L11 'P-site loop'. Chemical protection of wild-type ribosome shows that that the P-site loop is inherently flexible, i.e. it is extended into the ribosomal P-site when this is unoccupied by tRNA, while it is retracted into the terminal loop of 25S rRNA Helix 84 when the P-site is occupied. To further analyze the function of this structure, a series of mutants within the P-site loop were created and analyzed. A mutant that favors interaction of the P-site loop with the terminal loop of Helix 84 promoted increased affinity for peptidyl-tRNA, while another that favors its extension into the ribosomal P-site had the opposite effect. The two mutants also had opposing effects on binding of aa-tRNA to the ribosomal A-site, and downstream functional effects were observed on translational fidelity, drug resistance/hypersensitivity, virus maintenance and overall cell growth. These analyses suggest that the L11 P-site loop normally helps to optimize ribosome function by monitoring the occupancy status of the ribosomal P-site.
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Affiliation(s)
| | - Jonathan D. Dinman
- Department of Cell Biology and Molecular Genetics, Microbiology Building Room 2135, University of Maryland, College Park, MD 20742, USA
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22
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Abbasi N, Kim HB, Park NI, Kim HS, Kim YK, Park YI, Choi SB. APUM23, a nucleolar Puf domain protein, is involved in pre-ribosomal RNA processing and normal growth patterning in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:960-76. [PMID: 21143677 DOI: 10.1111/j.1365-313x.2010.04393.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Pumilio, an RNA-binding protein that contains tandemly repeated Puf domains, is known to repress translational activity in early embryogenesis and polarized cells of non-plant species. Although Pumilio proteins have been characterized in many eukaryotes, their role in plants is unknown. In the present study, we characterized an Arabidopsis Pumilio-encoding gene, APUM23. APUM23 is constitutively expressed, with higher levels in metabolically active tissues, and its expression is up-regulated in the presence of either glucose or sucrose. The T-DNA insertion mutants apum23-1 and apum23-2 showed slow growth, with serrated and scrunched leaves, an abnormal venation pattern, and distorted organization of the palisade parenchyma cells - a phenotype that is reminiscent of nucleolin and ribosomal protein gene mutants. Intracellular localization studies indicate that APUM23 predominantly localizes to the nucleolus. Based on this localization, rRNA processing was examined. In apum23, 35S pre-rRNA, and unprocessed 18S and 5.8S poly(A) rRNAs, accumulated without affecting the steady-state levels of mature rRNAs, indicating that APUM23 is involved in the processing and/or degradation of 35S pre-rRNA and rRNA maturation by-products. The apum23 mutant showed increased levels of 18S rRNA biogenesis-related U3 and U14 small nucleolar RNAs (snoRNAs) and accumulated RNAs within the nucleolus. Our data suggest that APUM23 plays an important role in plant development via rRNA processing.
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Affiliation(s)
- Nazia Abbasi
- School of Biotechnology and Environmental Engineering, Myongji University, Yongin, Kyunggi-do 449-728, South Korea
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23
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Meskauskas A, Dinman JD. A molecular clamp ensures allosteric coordination of peptidyltransfer and ligand binding to the ribosomal A-site. Nucleic Acids Res 2010; 38:7800-13. [PMID: 20660012 PMCID: PMC2995063 DOI: 10.1093/nar/gkq641] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Although the ribosome is mainly comprised of rRNA and many of its critical functions occur through RNA–RNA interactions, distinct domains of ribosomal proteins also participate in switching the ribosome between different conformational/functional states. Prior studies demonstrated that two extended domains of ribosomal protein L3 form an allosteric switch between the pre- and post-translocational states. Missing was an explanation for how the movements of these domains are communicated among the ribosome's functional centers. Here, a third domain of L3 called the basic thumb, that protrudes roughly perpendicular from the W-finger and is nestled in the center of a cagelike structure formed by elements from three separate domains of the large subunit rRNA is investigated. Mutagenesis of basically charged amino acids of the basic thumb to alanines followed by detailed analyses suggests that it acts as a molecular clamp, playing a role in allosterically communicating the ribosome's tRNA occupancy status to the elongation factor binding region and the peptidyltransferase center, facilitating coordination of their functions through the elongation cycle. The observation that these mutations affected translational fidelity, virus propagation and cell growth demonstrates how small structural changes at the atomic scale can propagate outward to broadly impact the biology of cell.
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Affiliation(s)
- Arturas Meskauskas
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA.
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24
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Petrov A, Puglisi JD. Site-specific labeling of Saccharomyces cerevisiae ribosomes for single-molecule manipulations. Nucleic Acids Res 2010; 38:e143. [PMID: 20501598 PMCID: PMC2910073 DOI: 10.1093/nar/gkq390] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Site-specific labeling of Escherichia coli ribosomes has allowed application of single-molecule fluorescence spectroscopy and force methods to probe the mechanism of translation. To apply these approaches to eukaryotic translation, eukaryotic ribosomes must be specifically labeled with fluorescent labels and molecular handles. Here, we describe preparation and labeling of the small and large yeast ribosomal subunits. Phylogenetically variable hairpin loops in ribosomal RNA are mutated to allow hybridization of oligonucleotides to mutant ribosomes. We demonstrate specific labeling of the ribosomal subunits, and their use in single-molecule fluorescence and force experiments.
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Affiliation(s)
- Alexey Petrov
- Department of Structural Biology and Stanford Magnetic Resonance Laboratory, Stanford University School of Medicine, Stanford, CA 94305-5126, USA
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25
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Chirkova A, Erlacher MD, Clementi N, Zywicki M, Aigner M, Polacek N. The role of the universally conserved A2450-C2063 base pair in the ribosomal peptidyl transferase center. Nucleic Acids Res 2010; 38:4844-55. [PMID: 20375101 PMCID: PMC2919715 DOI: 10.1093/nar/gkq213] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Despite the fact that all 23S rRNA nucleotides that build the ribosomal peptidyl transferase ribozyme are universally conserved, standard and atomic mutagenesis studies revealed the nucleobase identities being non-critical for catalysis. This indicates that these active site residues are highly conserved for functions distinct from catalysis. To gain insight into potential contributions, we have manipulated the nucleobases via an atomic mutagenesis approach and have utilized these chemically engineered ribosomes for in vitro translation reactions. We show that most of the active site nucleobases could be removed without significant effects on polypeptide production. Our data however highlight the functional importance of the universally conserved non-Watson-Crick base pair at position A2450-C2063. Modifications that disrupt this base pair markedly impair translation activities, while having little effects on peptide bond formation, tRNA drop-off and ribosome-dependent EF-G GTPase activity. Thus it seems that disruption of the A2450-C2063 pair inhibits a reaction following transpeptidation and EF-G action during the elongation cycle. Cumulatively our data are compatible with the hypothesis that the integrity of this A-C wobble base pair is essential for effective tRNA translocation through the peptidyl transferase center during protein synthesis.
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Affiliation(s)
- Anna Chirkova
- Innsbruck Biocenter, Medical University Innsbruck, Division of Genomics and RNomics, Innsbruck, Austria
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26
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Abstract
Protein synthesis is one of the major targets in the cell for antibiotics. This review endeavors to provide a comprehensive "post-ribosome structure" A-Z of the huge diversity of antibiotics that target the bacterial translation apparatus, with an emphasis on correlating the vast wealth of biochemical data with more recently available ribosome structures, in order to understand function. The binding site, mechanism of action, and modes of resistance for 26 different classes of protein synthesis inhibitors are presented, ranging from ABT-773 to Zyvox. In addition to improving our understanding of the process of translation, insight into the mechanism of action of antibiotics is essential to the development of novel and more effective antimicrobial agents to combat emerging bacterial resistance to many clinically-relevant drugs.
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Affiliation(s)
- Daniel N Wilson
- Gene Center and Department of Chemistry and Biochemistry, University of Munich, LMU, Munich, Germany.
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27
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28
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Van Dyke N, Pickering BF, Van Dyke MW. Stm1p alters the ribosome association of eukaryotic elongation factor 3 and affects translation elongation. Nucleic Acids Res 2009; 37:6116-25. [PMID: 19666721 PMCID: PMC2764444 DOI: 10.1093/nar/gkp645] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Stm1p is a Saccharomyces cerevisiae protein that is primarily associated with cytosolic 80S ribosomes and polysomes. Several lines of evidence suggest that Stm1p plays a role in translation under nutrient stress conditions, although its mechanism of action is not yet known. In this study, we show that yeast lacking Stm1p (stm1Delta) are hypersensitive to the translation inhibitor anisomycin, which affects the peptidyl transferase reaction in translation elongation, but show little hypersensitivity to other translation inhibitors such as paromomycin and hygromycin B, which affect translation fidelity. Ribosomes isolated from stm1Delta yeast have intrinsically elevated levels of eukaryotic elongation factor 3 (eEF3) associated with them. Overexpression of eEF3 in cells lacking Stm1p results in a growth defect phenotype and increased anisomycin sensitivity. In addition, ribosomes with increased levels of Stm1p exhibit decreased association with eEF3. Taken together, our data indicate that Stm1p plays a complementary role to eEF3 in translation.
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Affiliation(s)
- Natalya Van Dyke
- Department of Molecular and Cellular Oncology, Unit 079, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA
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29
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Abstract
Despite having been identified first, their greater degree of complexity has resulted in our understanding of eukaryotic ribosomes lagging behind that of their bacterial and archaeal counterparts. A much more complicated biogenesis program results in ribosomes that are structurally, biochemically, and functionally more complex. However, recent advances in molecular genetics and structural biology are helping to reveal the intricacies of the eukaryotic ribosome and to address many longstanding questions regarding its many roles in the regulation of gene expression.
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Affiliation(s)
- Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA.
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30
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Fujii K, Kitabatake M, Sakata T, Miyata A, Ohno M. A role for ubiquitin in the clearance of nonfunctional rRNAs. Genes Dev 2009; 23:963-74. [PMID: 19390089 DOI: 10.1101/gad.1775609] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Quality control mechanisms operate in various steps of ribosomal biogenesis to ensure the production of functional ribosome particles. It was reported previously that mature ribosome particles containing nonfunctional mutant rRNAs are also recognized and selectively removed by a cellular quality control system (nonfunctional rRNA decay [NRD]). Here, we show that the NRD of 25S rRNA requires a ubiquitin E3 ligase component Rtt101p and its associated protein Mms1p, identified previously as factors involved in DNA repair. We revealed that a group of proteins associated with nonfunctional ribosome particles are ubiquitinated in a Rtt101-Mms1-dependent manner. 25S NRD was disrupted when ubiquitination was inhibited by the overexpression of modified ubiquitin molecules, demonstrating a direct role for ubiquitin in this pathway. These results uncovered an unexpected connection between DNA repair and the quality control of rRNAs. Our findings support a model in which responses to DNA and rRNA damages are triggered by a common ubiquitin ligase complex during genotoxic stress harmful to both molecules.
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Affiliation(s)
- Kotaro Fujii
- Institute for Virus Research, Kyoto University, Kyoto, Japan
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31
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Current awareness on yeast. Yeast 2008. [DOI: 10.1002/yea.1558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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32
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Petrov AN, Meskauskas A, Roshwalb SC, Dinman JD. Yeast ribosomal protein L10 helps coordinate tRNA movement through the large subunit. Nucleic Acids Res 2008; 36:6187-98. [PMID: 18824477 PMCID: PMC2577338 DOI: 10.1093/nar/gkn643] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 09/16/2008] [Accepted: 09/17/2008] [Indexed: 11/18/2022] Open
Abstract
Yeast ribosomal protein L10 (E. coli L16) is located at the center of a topological nexus that connects many functional regions of the large subunit. This essential protein has previously been implicated in processes as diverse as ribosome biogenesis, translational fidelity and mRNA stability. Here, the inability to maintain the yeast Killer virus was used as a proxy for large subunit defects to identify a series of L10 mutants. These mapped to roughly four discrete regions of the protein. A detailed analysis of mutants located in the N-terminal 'hook' of L10, which inserts into the bulge of 25S rRNA helix 89, revealed strong effects on rRNA structure corresponding to the entire path taken by the tRNA 3' end as it moves through the large subunit during the elongation cycle. The mutant-induced structural changes are wide-ranging, affecting ribosome biogenesis, elongation factor binding, drug resistance/hypersensitivity, translational fidelity and virus maintenance. The importance of L10 as a potential transducer of information through the ribosome, and of a possible role of its N-terminal domain in switching between the pre- and post-translocational states are discussed.
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Affiliation(s)
| | | | | | - Jonathan D. Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, 2135 Microbiology Building, College Park, MD 20742, USA
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33
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Goodey NM, Benkovic SJ. Allosteric regulation and catalysis emerge via a common route. Nat Chem Biol 2008; 4:474-82. [PMID: 18641628 DOI: 10.1038/nchembio.98] [Citation(s) in RCA: 527] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Allosteric regulation of protein function is a mechanism by which an event in one place of a protein structure causes an effect at another site, much like the behavior of a telecommunications network in which a collection of transmitters, receivers and transceivers communicate with each other across long distances. For example, ligand binding or an amino acid mutation at an allosteric site can alter enzymatic activity or binding affinity in a distal region such as the active site or a second binding site. The mechanism of this site-to-site communication is of great interest, especially since allosteric effects must be considered in drug design and protein engineering. In this review, conformational mobility as the common route between allosteric regulation and catalysis is discussed. We summarize recent experimental data and the resulting insights into allostery within proteins, and we discuss the nature of future studies and the new applications that may result from increased understanding of this regulatory mechanism.
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Affiliation(s)
- Nina M Goodey
- Montclair State University, Department of Chemistry and Biochemistry, 1 Normal Avenue, Montclair, New Jersey 07043, USA
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34
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Blaha G, Gürel G, Schroeder SJ, Moore PB, Steitz TA. Mutations outside the anisomycin-binding site can make ribosomes drug-resistant. J Mol Biol 2008; 379:505-19. [PMID: 18455733 DOI: 10.1016/j.jmb.2008.03.075] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 02/26/2008] [Accepted: 03/19/2008] [Indexed: 01/19/2023]
Abstract
Eleven mutations that make Haloarcula marismortui resistant to anisomycin, an antibiotic that competes with the amino acid side chains of aminoacyl tRNAs for binding to the A-site cleft of the large ribosomal unit, have been identified in 23S rRNA. The correlation observed between the sensitivity of H. marismortui to anisomycin and the affinity of its large ribosomal subunits for the drug indicates that its response to anisomycin is determined primarily by the binding of the drug to its large ribosomal subunit. The structures of large ribosomal subunits containing resistance mutations show that these mutations can be divided into two classes: (1) those that interfere with specific drug-ribosome interactions and (2) those that stabilize the apo conformation of the A-site cleft of the ribosome relative to its drug-bound conformation. The conformational effects of some mutations of the second kind propagate through the ribosome for considerable distances and are reversed when A-site substrates bind to the ribosome.
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Affiliation(s)
- Gregor Blaha
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
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