1
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Powers KT, Stevenson-Jones F, Yadav SKN, Amthor B, Bufton JC, Borucu U, Shen D, Becker JP, Lavysh D, Hentze MW, Kulozik AE, Neu-Yilik G, Schaffitzel C. Blasticidin S inhibits mammalian translation and enhances production of protein encoded by nonsense mRNA. Nucleic Acids Res 2021; 49:7665-7679. [PMID: 34157102 PMCID: PMC8287960 DOI: 10.1093/nar/gkab532] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/16/2021] [Accepted: 06/08/2021] [Indexed: 12/14/2022] Open
Abstract
Deciphering translation is of paramount importance for the understanding of many diseases, and antibiotics played a pivotal role in this endeavour. Blasticidin S (BlaS) targets translation by binding to the peptidyl transferase center of the large ribosomal subunit. Using biochemical, structural and cellular approaches, we show here that BlaS inhibits both translation elongation and termination in Mammalia. Bound to mammalian terminating ribosomes, BlaS distorts the 3′CCA tail of the P-site tRNA to a larger extent than previously reported for bacterial ribosomes, thus delaying both, peptide bond formation and peptidyl-tRNA hydrolysis. While BlaS does not inhibit stop codon recognition by the eukaryotic release factor 1 (eRF1), it interferes with eRF1’s accommodation into the peptidyl transferase center and subsequent peptide release. In human cells, BlaS inhibits nonsense-mediated mRNA decay and, at subinhibitory concentrations, modulates translation dynamics at premature termination codons leading to enhanced protein production.
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Affiliation(s)
- Kyle T Powers
- University of Bristol, School of Biochemistry, University Walk, Bristol BS8 1TD, UK
| | | | - Sathish K N Yadav
- University of Bristol, School of Biochemistry, University Walk, Bristol BS8 1TD, UK
| | - Beate Amthor
- Department of Pediatric Oncology, Hematology and Immunology, Hopp Children's Cancer Research Center Heidelberg (KiTZ), University of Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit (MMPU) European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Heidelberg, Germany
| | - Joshua C Bufton
- University of Bristol, School of Biochemistry, University Walk, Bristol BS8 1TD, UK
| | - Ufuk Borucu
- University of Bristol, School of Biochemistry, University Walk, Bristol BS8 1TD, UK
| | - Dakang Shen
- University of Bristol, School of Biochemistry, University Walk, Bristol BS8 1TD, UK
| | - Jonas P Becker
- Department of Pediatric Oncology, Hematology and Immunology, Hopp Children's Cancer Research Center Heidelberg (KiTZ), University of Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit (MMPU) European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Heidelberg, Germany
| | - Daria Lavysh
- Department of Pediatric Oncology, Hematology and Immunology, Hopp Children's Cancer Research Center Heidelberg (KiTZ), University of Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit (MMPU) European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Heidelberg, Germany
| | - Matthias W Hentze
- Molecular Medicine Partnership Unit (MMPU) European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Heidelberg, Germany.,European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Andreas E Kulozik
- Department of Pediatric Oncology, Hematology and Immunology, Hopp Children's Cancer Research Center Heidelberg (KiTZ), University of Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit (MMPU) European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Heidelberg, Germany
| | - Gabriele Neu-Yilik
- Department of Pediatric Oncology, Hematology and Immunology, Hopp Children's Cancer Research Center Heidelberg (KiTZ), University of Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit (MMPU) European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Heidelberg, Germany
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2
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Sathoff AE, Lewenza S, Samac DA. Plant defensin antibacterial mode of action against Pseudomonas species. BMC Microbiol 2020; 20:173. [PMID: 32560676 PMCID: PMC7304088 DOI: 10.1186/s12866-020-01852-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 06/12/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn5-lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to create mutants that are resistant to in vitro MtDef4 treatments. RESULTS Plant defensins displayed specific and potent antibacterial activity against strains of P. aeruginosa. A defensin from Medicago truncatula, MtDef4, induced dose-dependent gene expression of the aminoarabinose modification of LPS and surface polycation spermidine production operons. The ability for MtDef4 to damage bacterial outer membranes was also verified visually through fluorescent microscopy. Another defensin from M. truncatula, MtDef5, failed to induce lux gene expression and limited outer membrane damage was detected with fluorescent microscopy. The transposon insertion site on MtDef4 resistant P. syringae pv. syringae mutants was sequenced, and modifications of ribosomal genes were identified to contribute to enhanced resistance to plant defensin treatments. CONCLUSIONS MtDef4 damages the outer membrane similar to polymyxin B, which stimulates antimicrobial peptide resistance mechanisms to plant defensins. MtDef5, appears to have a different antibacterial MOA. Additionally, the MtDef4 antibacterial mode of action may also involve inhibition of translation.
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Affiliation(s)
- Andrew E Sathoff
- Department of Plant Pathology, 1991 Upper Buford Circle, University of Minnesota, St. Paul, MN, 55108, USA. .,Department of Biology, Dakota State University, 820 N Washington Ave, Madison, SD, 57042, USA.
| | - Shawn Lewenza
- Department of Microbiology and Infectious Disease, 3330 Hospital Dr. N.W., University of Calgary, Calgary, AB, T2N 4Z6, Canada.,Faculty of Science and Technology, 1 University Dr., Athabasca University, Athabasca, AB, T9S 3A3, Canada
| | - Deborah A Samac
- Department of Plant Pathology, 1991 Upper Buford Circle, University of Minnesota, St. Paul, MN, 55108, USA.,USDA-ARS, Plant Science Research Unit, 1991 Upper Buford Circle, St. Paul, MN, 55108, USA
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3
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Shin BS, Katoh T, Gutierrez E, Kim JR, Suga H, Dever TE. Amino acid substrates impose polyamine, eIF5A, or hypusine requirement for peptide synthesis. Nucleic Acids Res 2017; 45:8392-8402. [PMID: 28637321 PMCID: PMC5737446 DOI: 10.1093/nar/gkx532] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/05/2017] [Accepted: 06/08/2017] [Indexed: 01/20/2023] Open
Abstract
Whereas ribosomes efficiently catalyze peptide bond synthesis by most amino acids, the imino acid proline is a poor substrate for protein synthesis. Previous studies have shown that the translation factor eIF5A and its bacterial ortholog EF-P bind in the E site of the ribosome where they contact the peptidyl-tRNA in the P site and play a critical role in promoting the synthesis of polyproline peptides. Using misacylated Pro-tRNAPhe and Phe-tRNAPro, we show that the imino acid proline and not tRNAPro imposes the primary eIF5A requirement for polyproline synthesis. Though most proline analogs require eIF5A for efficient peptide synthesis, azetidine-2-caboxylic acid, a more flexible four-membered ring derivative of proline, shows relaxed eIF5A dependency, indicating that the structural rigidity of proline might contribute to the requirement for eIF5A. Finally, we examine the interplay between eIF5A and polyamines in promoting translation elongation. We show that eIF5A can obviate the polyamine requirement for general translation elongation, and that this activity is independent of the conserved hypusine modification on eIF5A. Thus, we propose that the body of eIF5A functionally substitutes for polyamines to promote general protein synthesis and that the hypusine modification on eIF5A is critically important for poor substrates like proline.
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Affiliation(s)
- Byung-Sik Shin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Takayuki Katoh
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Erik Gutierrez
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joo-Ran Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Thomas E. Dever
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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4
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Abstract
Recent progress with techniques for monitoring RNA structure in cells such as ‘DMS-Seq’ and ‘Structure-Seq’ suggests that a new era of RNA structure-function exploration is on the horizon. This will also include systematic investigation of the factors required for the structural integrity of RNA. In this context, much evidence accumulated over 50 years suggests that polyamines play important roles as modulators of RNA structure. Here, we summarize and discuss recent literature relating to the roles of these small endogenous molecules in RNA function. We have included studies directed at understanding the binding interactions of polyamines with polynucleotides, tRNA, rRNA, mRNA and ribozymes using chemical, biochemical and spectroscopic tools. In brief, polyamines bind RNA in a sequence-selective fashion and induce changes in RNA structure in context-dependent manners. In some cases the functional consequences of these interactions have been observed in cells. Most notably, polyamine-mediated effects on RNA are frequently distinct from those of divalent cations (i.e. Mg2+) confirming their roles as independent molecular entities which help drive RNA-mediated processes.
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Affiliation(s)
- Helen L Lightfoot
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, CH-8093, Zürich, Switzerland
| | - Jonathan Hall
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, CH-8093, Zürich, Switzerland
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5
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Wilson D. Peptidyltransferase Inhibitors of the Bacterial Ribosome. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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6
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Blasticidin S inhibits translation by trapping deformed tRNA on the ribosome. Proc Natl Acad Sci U S A 2013; 110:12283-8. [PMID: 23824292 DOI: 10.1073/pnas.1304922110] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The antibiotic blasticidin S (BlaS) is a potent inhibitor of protein synthesis in bacteria and eukaryotes. We have determined a 3.4-Å crystal structure of BlaS bound to a 70S⋅tRNA ribosome complex and performed biochemical and single-molecule FRET experiments to determine the mechanism of action of the antibiotic. We find that BlaS enhances tRNA binding to the P site of the large ribosomal subunit and slows down spontaneous intersubunit rotation in pretranslocation ribosomes. However, the antibiotic has negligible effect on elongation factor G catalyzed translocation of tRNA and mRNA. The crystal structure of the antibiotic-ribosome complex reveals that BlaS impedes protein synthesis through a unique mechanism by bending the 3' terminus of the P-site tRNA toward the A site of the large ribosomal subunit. Biochemical experiments demonstrate that stabilization of the deformed conformation of the P-site tRNA by BlaS strongly inhibits peptidyl-tRNA hydrolysis by release factors and, to a lesser extent, peptide bond formation.
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7
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Pytharopoulou S, Kournoutou GG, Leotsinidis M, Georgiou CD, Kalpaxis DL. Dysfunctions of the translational machinery in digestive glands of mussels exposed to mercury ions. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 134-135:23-33. [PMID: 23537583 DOI: 10.1016/j.aquatox.2013.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Revised: 02/20/2013] [Accepted: 02/26/2013] [Indexed: 06/02/2023]
Abstract
Mercury is an element naturally occurring in the biosphere, but is also released into the environment by human activities, such as mining, smelting, and industrial discharge. Mercury is a biologically harmful element and any exposure of living organisms mainly due to contamination, can cause severe or even lethal side effects. In every form detected, elemental, inorganic, or organic, mercury exhibits toxicity associated with induced oxidative stress. Although the genotoxicity of mercury has been well demonstrated in mussels, little is known about its toxic effects on the translational machinery at the molecular level. To investigate possible effects, we exposed the common mussel Mytilus galloprovincialis in seawater supplemented by 30 μg/L Hg²⁺ for 15 days. We observed that Hg²⁺ was significantly accumulated in the digestive glands of mussels, reaching a level around 80 μg/g tissue (dry weight) at the 15th day of exposure. Exposure of mussels to Hg²⁺ resulted in failure of redox homeostasis, as reflected on lipid peroxidation levels and superoxide dismutase activity in glands, and micronucleus frequency in gills. Extracts from digestive glands after 15-day exposure to Hg²⁺ exhibited decreased tRNA aminoacylation ability and, moreover, a 70% reduction in the ability of 40S ribosomal subunits to form the 48S initiation ribosomal complex. A similar reduction was detected in the ability of ribosomes to translocate peptidyl-tRNA from the A-site to the P-site, an observation coinciding with the notion that regulation of protein synthesis by Hg²⁺ mainly occurs at the initiation and elongation stages of translation. A-site binding, peptidyl transferase activity, and termination of peptide chain synthesis underwent less pronounced but measurable reductions, a finding which explains why poly(Phe)-synthesis in ribosomes isolated from exposed mussels is reduced by 70%. In conclusion, Hg²⁺ apart from being a genotoxic ion acts as a modulator of protein synthesis in mussels, an observation probably related with its ability to induce oxidative stress.
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Affiliation(s)
- Sofia Pytharopoulou
- Laboratory of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
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8
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Kostopoulou ON, Petropoulos AD, Dinos GP, Choli-Papadopoulou T, Kalpaxis DL. Investigating the entire course of telithromycin binding to Escherichia coli ribosomes. Nucleic Acids Res 2012; 40:5078-87. [PMID: 22362747 PMCID: PMC3367204 DOI: 10.1093/nar/gks174] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Applying kinetics and footprinting analysis, we show that telithromycin, a ketolide antibiotic, binds to Escherichia coli ribosomes in a two-step process. During the first, rapidly equilibrated step, telithromycin binds to a low-affinity site (KT = 500 nM), in which the lactone ring is positioned at the upper portion of the peptide exit tunnel, while the alkyl–aryl side chain of the drug inserts a groove formed by nucleotides A789 and U790 of 23S rRNA. During the second step, telithromycin shifts slowly to a high-affinity site (KT* = 8.33 nM), in which the lactone ring remains essentially at the same position, while the side chain interacts with the base pair U2609:A752 and the extended loop of protein L22. Consistently, mutations perturbing either the base pair U2609:A752 or the L22-loop hinder shifting of telithromycin to the final position, without affecting the initial step of binding. In contrast, mutation Lys63Glu in protein L4 placed on the opposite side of the tunnel, exerts only a minor effect on telithromycin binding. Polyamines disfavor both sequential steps of binding. Our data correlate well with recent crystallographic data and rationalize the changes in the accessibility of ribosomes to telithromycin in response to ribosomal mutations and ionic changes.
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Affiliation(s)
- Ourania N Kostopoulou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
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9
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Duke SO, Dayan FE. Modes of action of microbially-produced phytotoxins. Toxins (Basel) 2011; 3:1038-1064. [PMID: 22069756 PMCID: PMC3202864 DOI: 10.3390/toxins3081038] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 08/15/2011] [Accepted: 08/17/2011] [Indexed: 01/17/2023] Open
Abstract
Some of the most potent phytotoxins are synthesized by microbes. A few of these share molecular target sites with some synthetic herbicides, but many microbial toxins have unique target sites with potential for exploitation by the herbicide industry. Compounds from both non-pathogenic and pathogenic microbes are discussed. Microbial phytotoxins with modes of action the same as those of commercial herbicides and those with novel modes of action of action are covered. Examples of the compounds discussed are tentoxin, AAL-toxin, auscaulitoxin aglycone, hydantocidin, thaxtomin, and tabtoxin.
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Affiliation(s)
- Stephen O. Duke
- United States Department of Agriculture, Agricultural Research Service, Natural Products Utilization Research Unit, P. O. Box 8048, MS 38677, USA;
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10
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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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11
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Vourekas A, Stamatopoulou V, Toumpeki C, Tsitlaidou M, Drainas D. Insights into functional modulation of catalytic RNA activity. IUBMB Life 2008; 60:669-83. [PMID: 18636557 DOI: 10.1002/iub.105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
RNA molecules play critical roles in cell biology, and novel findings continuously broaden their functional repertoires. Apart from their well-documented participation in protein synthesis, it is now apparent that several noncoding RNAs (i.e., micro-RNAs and riboswitches) also participate in the regulation of gene expression. The discovery of catalytic RNAs had profound implications on our views concerning the evolution of life on our planet at a molecular level. A characteristic attribute of RNA, probably traced back to its ancestral origin, is the ability to interact with and be modulated by several ions and molecules of different sizes. The inhibition of ribosome activity by antibiotics has been extensively used as a therapeutical approach, while activation and substrate-specificity alteration have the potential to enhance the versatility of ribozyme-based tools in translational research. In this review, we will describe some representative examples of such modulators to illustrate the potential of catalytic RNAs as tools and targets in research and clinical approaches.
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Affiliation(s)
- Anastassios Vourekas
- Department of Biological Chemistry, School of Medicine, University of Patras, Rio-Patras, Greece
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12
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Szaflarski W, Vesper O, Teraoka Y, Plitta B, Wilson DN, Nierhaus KH. New features of the ribosome and ribosomal inhibitors: non-enzymatic recycling, misreading and back-translocation. J Mol Biol 2008; 380:193-205. [PMID: 18508080 DOI: 10.1016/j.jmb.2008.04.060] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 04/24/2008] [Accepted: 04/25/2008] [Indexed: 10/22/2022]
Abstract
We describe the optimization of a poly(Phe) synthesis system, the conditions of which have been applied for efficient translation of heteropolymeric mRNAs. Here we identify two parameters that are essential to obtain translation at efficiency and accuracy levels equivalent to those in vivo, viz., the fine-tuning of the energy-rich components with an acetyl-phosphate substrate for energy regeneration, as well as the ionic conditions. Applying this system revealed a number of new features: (i) 70S ribosomes are able to recycle within 300 s in a non-enzymatic fashion in the absence of tmRNA. This observation might explain the fact that a knockout of the tmRNA gene ssrA is not lethal for Escherichia coli cells in contrast to other bacterial strains, such as Bacillus subtilis. (ii) The high efficiency of the system was exploited to analyze the misincorporation of various amino acids (resolution limit=1:15,000). No misreading was observed at the middle codon position and only marginal effects were observed at the first one (even when misreading was artificially stimulated 20- to 30-fold), yielding an improved definition of the near-cognate and non-cognate aminoacyl-tRNAs. (iii) Aminoglycosides increase Phe and Lys incorporation about 2-fold in the presence of poly(U) or poly(UUC) and poly(A), respectively, and induce a back-translocation (except hygromycin B) exclusively in the absence of EF-G*GTP, as do the non-related drugs viomycin and edeine.
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Affiliation(s)
- Witold Szaflarski
- Max-Planck-Institut für Molekulare Genetik, AG Ribosomen, Ihnestr. 73, D-14195 Berlin, Germany
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13
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Petropoulos AD, Kouvela EC, Dinos GP, Kalpaxis DL. Stepwise binding of tylosin and erythromycin to Escherichia coli ribosomes, characterized by kinetic and footprinting analysis. J Biol Chem 2007; 283:4756-65. [PMID: 18079110 DOI: 10.1074/jbc.m708371200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Erythromycin and tylosin are 14- and 16-membered lactone ring macrolides, respectively. The current work shows by means of kinetic and chemical footprinting analysis that both antibiotics bind to Escherichia coli ribosomes in a two-step process. The first step established rapidly, involves a low-affinity binding site placed at the entrance of the exit tunnel in the large ribosomal subunit, where macrolides bind primarily through their hydrophobic portions. Subsequently, slow conformational changes mediated by the antibiotic hydrophilic portion push the drugs deeper into the tunnel, in a high-affinity site. Compared with erythromycin, tylosin shifts to the high-affinity site more rapidly, due to the interaction of the mycinose sugar of the drug with the loop of H35 in domain II of 23 S rRNA. Consistently, mutations of nucleosides U2609 and U754 implicated in the high-affinity site reduce the shift of tylosin to this site and destabilize, respectively, the final drug-ribosome complex. The weak interaction between tylosin and the ribosome is Mg2+ independent, unlike the tight binding. In contrast, both interactions between erythromycin and the ribosome are reduced by increasing concentrations of Mg2+ ions. Polyamines attenuate erythromycin affinity for the ribosome at both sequential steps of binding. In contrast, polyamines facilitate the initial binding of tylosin, but exert a detrimental, more pronounced, effect on the drug accommodation at its final position. Our results emphasize the role of the particular interactions that side chains of tylosin and erythromycin establish with 23 S rRNA, which govern the exact binding process of each drug and its response to the ionic environment.
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14
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Tkachenko AG, Pozhidaeva ON, Shumkov MS. Role of polyamines in formation of multiple antibiotic resistance of Escherichia coli under stress conditions. BIOCHEMISTRY (MOSCOW) 2006; 71:1042-9. [PMID: 17009960 DOI: 10.1134/s0006297906090148] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Under stress conditions, polyamines decreased the permeability of the outer membrane of Escherichia coli. This effect is caused by at least three mechanisms providing for an increase in the resistance to antibiotics transported through porin channels (fluoroquinolones, beta-lactams): a positive modulation of the gene micF transcription (its product antisense RNA inhibits the synthesis of porin proteins on the translational level); a positive effect on the cell content of the multiple stress resistance factor sigma(S) (it is accompanied by a decrease in the porin transport because of suppression of ompF transcription and induction of cadaverine synthesis); a direct inhibition of the transport activity of porin channels. The production of cadaverine in E. coli cells significantly increased in response to various antibiotics, and this was likely to be a manifestation of oxidative stress.
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Affiliation(s)
- A G Tkachenko
- Institute of Ecology and Genetics of Microorganisms, Ural Division, Russian Academy of Sciences, Perm 614081, Russia.
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15
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Kouvela EC, Petropoulos AD, Kalpaxis DL. Unraveling New Features of Clindamycin Interaction with Functional Ribosomes and Dependence of the Drug Potency on Polyamines. J Biol Chem 2006; 281:23103-10. [PMID: 16760473 DOI: 10.1074/jbc.m603263200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The effect of spermine on the inhibition of peptide-bond formation by clindamycin, an antibiotic of the Macrolide-Lincosamide-StreptograminsB family, was investigated in a cell-free system derived from Escherichia coli. In this system peptide bond is formed between puromycin, a pseudo-substrate of the A-site, and acetylphenylalanyl-tRNA, bound at the P-site of poly(U)-programmed 70 S ribosomes. Biphasic kinetics revealed that one molecule of clindamycin, after a transient interference with the A-site of ribosomes, is slowly accommodated near the P-site and perturbs the 70 S/acetylphenylalanyl-tRNA complex so that a peptide bond is still formed but with a lower velocity compared with that observed in the absence of the drug. The above mechanism requires a high temperature (25 degrees C as opposed to 5 degrees C). If this is not met, the inhibition is simple competitive. It was found that at 25 degrees C spermine favors the clindamycin binding to ribosomes; the affinity of clindamycin for the A-site becomes 5 times higher, whereas the overall inhibition constant undergoes a 3-fold decrease. Similar results were obtained when ribosomes labeled with N1-azidobenzamidinospermine, a photo-reactive analogue of spermine, were used or when a mixture of spermine and spermidine was added in the reaction mixture instead of spermine alone. Polyamines cannot compensate for the loss of biphasic kinetics at 5 degrees C nor can they stimulate the clindamycin binding to ribosomes. Our kinetic results correlate well with photoaffinity labeling data, suggesting that at 25 degrees C polyamines bound at the vicinity of the drug binding pocket affect the tertiary structure of ribosomes and influence their interaction with clindamycin.
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Affiliation(s)
- Ekaterini C Kouvela
- Laboratory of Biochemistry, School of Medicine, University of Patras, 26500 Patras, Greece
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16
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Jeannot K, Sobel ML, El Garch F, Poole K, Plésiat P. Induction of the MexXY efflux pump in Pseudomonas aeruginosa is dependent on drug-ribosome interaction. J Bacteriol 2005; 187:5341-6. [PMID: 16030228 PMCID: PMC1196038 DOI: 10.1128/jb.187.15.5341-5346.2005] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MexXY is an inducible efflux system that contributes to the natural resistance of Pseudomonas aeruginosa to antibiotics. Experiments involving real-time PCR after reverse transcription in reference strain PAO1 showed concentration-dependent induction of gene mexY by various ribosome inhibitors (e.g., chloramphenicol, tetracycline, macrolides, and aminoglycosides) but not by antibiotics acting on other cellular targets (e.g., beta-lactams, fluoroquinolones). Confirming a functional link between the efflux system and the translational machinery, ribosome protection by plasmid-encoded proteins TetO and ErmBP increased the resistance of a DeltamexAB-oprM mutant of PAO1 to tetracycline and erythromycin, respectively, as well as the concentrations of both drugs required to induce mexY. Furthermore, spontaneous mutations resulting in specific resistance to dihydrostreptomycin or spectinomycin also raised the minimal drug concentration for mexXY induction in strain PAO1. While strongly upregulated in a PAO1 mutant defective in gene mexZ (which codes for a putative repressor of operon mexXY), gene mexY remained inducible by agents such as tetracycline, chloramphenicol, and spectinomycin, suggesting additional regulatory loci for mexXY. Altogether, these data demonstrate physiological interplays between MexXY and the ribosome and are suggestive of an alternative function for MexXY beyond antibiotic efflux.
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Affiliation(s)
- Katy Jeannot
- Laboratoire de Bactériologie, Hôpital Jean Minjoz, 25030 Besançon Cedex, France
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Paschalidis KA, Roubelakis-Angelakis KA. Sites and regulation of polyamine catabolism in the tobacco plant. Correlations with cell division/expansion, cell cycle progression, and vascular development. PLANT PHYSIOLOGY 2005; 138:2174-84. [PMID: 16040649 PMCID: PMC1183405 DOI: 10.1104/pp.105.063941] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 04/28/2005] [Accepted: 04/30/2005] [Indexed: 05/03/2023]
Abstract
We previously gave a picture of the homeostatic characteristics of polyamine (PA) biosynthesis and conjugation in tobacco (Nicotiana tabacum) plant organs during development. In this work, we present the sites and regulation of PA catabolism related to cell division/expansion, cell cycle progression, and vascular development in the tobacco plant. Diamine oxidase (DAO), PA oxidase (PAO), peroxidases (POXs), and putrescine N-methyltransferase expressions follow temporally and spatially discrete patterns in shoot apical cells, leaves (apical, peripheral, and central regions), acropetal and basipetal petiole regions, internodes, and young and old roots in developing plants. DAO and PAO produce hydrogen peroxide, a plant signal molecule and substrate for POXs. Gene expression and immunohistochemistry analyses reveal that amine oxidases in developing tobacco tissues precede and overlap with nascent nuclear DNA and also with POXs and lignification. In mature and old tissues, flow cytometry indicates that amine oxidase and POX activities, as well as pao gene and PAO protein levels, coincide with G2 nuclear phase and endoreduplication. In young versus the older roots, amine oxidases and POX expression decrease with parallel inhibition of G2 advance and endoreduplication, whereas putrescine N-methyltransferase dramatically increases. In both hypergeous and hypogeous tissues, DAO and PAO expression occurs in cells destined to undergo lignification, suggesting a different in situ localization. DNA synthesis early in development and the advance in cell cycle/endocycle are temporally and spatially related to PA catabolism and vascular development.
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Xaplanteri MA, Petropoulos AD, Dinos GP, Kalpaxis DL. Localization of spermine binding sites in 23S rRNA by photoaffinity labeling: parsing the spermine contribution to ribosomal 50S subunit functions. Nucleic Acids Res 2005; 33:2792-805. [PMID: 15897324 PMCID: PMC1129027 DOI: 10.1093/nar/gki557] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polyamine binding to 23S rRNA was investigated, using a photoaffinity labeling approach. This was based on the covalent binding of a photoreactive analog of spermine, N1-azidobenzamidino (ABA)-spermine, to Escherichia coli ribosomes or naked 23S rRNA under mild irradiation conditions. The cross-linking sites of ABA-spermine in 23S rRNA were determined by RNase H digestion and primer-extension analysis. Domains I, II, IV and V in naked 23S rRNA were identified as discrete regions of preferred cross-linking. When 50S ribosomal subunits were targeted, the interaction of the photoprobe with the above 23S rRNA domains was elevated, except for helix H38 in domain II whose susceptibility to cross-linking was greatly reduced. In addition, cross-linking sites were identified in domains III and VI. Association of 30S with 50S subunits, poly(U), tRNAPhe and AcPhe-tRNA to form a post-translocation complex further altered the cross-linking, in particular to helices H11–H13, H21, H63, H80, H84, H90 and H97. Poly(U)-programmed 70S ribosomes, reconstituted from photolabeled 50S subunits and untreated 30S subunits, bound AcPhe-tRNA in a similar fashion to native ribosomes. However, they exhibited higher reactivity toward puromycin and enhanced tRNA-translocation efficiency. These results suggest an essential role for polyamines in the structural and functional integrity of the large ribosomal subunit.
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Affiliation(s)
| | | | | | - Dimitrios L. Kalpaxis
- To whom correspondence should be addressed. Tel: +30 2610 996124; Fax: +30 2610 997690;
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Abstract
Members of the macrolide class of antibiotics inhibit peptide elongation on the ribosome by binding close to the peptidyltransferase center and blocking the peptide exit tunnel in the large ribosomal subunit. We have studied the modes of action of the macrolides josamycin, with a 16-membered lactone ring, and erythromycin, with a 14-membered lactone ring, in a cell-free mRNA translation system with pure components from Escherichia coli. We have found that the average lifetime on the ribosome is 3 h for josamycin and less than 2 min for erythromycin and that the dissociation constants for josamycin and erythromycin binding to the ribosome are 5.5 and 11 nM, respectively. Josamycin slows down formation of the first peptide bond of a nascent peptide in an amino acid-dependent way and completely inhibits formation of the second or third peptide bond, depending on peptide sequence. Erythromycin allows formation of longer peptide chains before the onset of inhibition. Both drugs stimulate the rate constants for drop-off of peptidyl-tRNA from the ribosome. In the josamycin case, drop-off is much faster than drug dissociation, whereas these rate constants are comparable in the erythromycin case. Therefore, at a saturating drug concentration, synthesis of full-length proteins is completely shut down by josamycin but not by erythromycin. It is likely that the bacterio-toxic effects of the drugs are caused by a combination of inhibition of protein elongation, on the one hand, and depletion of the intracellular pools of aminoacyl-tRNAs available for protein synthesis by drop-off and incomplete peptidyl-tRNA hydrolase activity, on the other hand.
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Affiliation(s)
- Martin Lovmar
- Department of Cell and Molecular Biology, Molecular Biology Program, BMC, Box 596, Uppsala University, S-75124 Uppsala, Sweden
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