1
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Seely SM, Basu RS, Gagnon MG. Mechanistic insights into the alternative ribosome recycling by HflXr. Nucleic Acids Res 2024; 52:4053-4066. [PMID: 38407413 DOI: 10.1093/nar/gkae128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/02/2024] [Accepted: 02/19/2024] [Indexed: 02/27/2024] Open
Abstract
During stress conditions such as heat shock and antibiotic exposure, ribosomes stall on messenger RNAs, leading to inhibition of protein synthesis. To remobilize ribosomes, bacteria use rescue factors such as HflXr, a homolog of the conserved housekeeping GTPase HflX that catalyzes the dissociation of translationally inactive ribosomes into individual subunits. Here we use time-resolved cryo-electron microscopy to elucidate the mechanism of ribosome recycling by Listeria monocytogenes HflXr. Within the 70S ribosome, HflXr displaces helix H69 of the 50S subunit and induces long-range movements of the platform domain of the 30S subunit, disrupting inter-subunit bridges B2b, B2c, B4, B7a and B7b. Our findings unveil a unique ribosome recycling strategy by HflXr which is distinct from that mediated by RRF and EF-G. The resemblance between HflXr and housekeeping HflX suggests that the alternative ribosome recycling mechanism reported here is universal in the prokaryotic kingdom.
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Affiliation(s)
- Savannah M Seely
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Ritwika S Basu
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Matthieu G Gagnon
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
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2
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Rybak MY, Gagnon MG. Structures of the ribosome bound to EF-Tu-isoleucine tRNA elucidate the mechanism of AUG avoidance. Nat Struct Mol Biol 2024:10.1038/s41594-024-01236-3. [PMID: 38538914 DOI: 10.1038/s41594-024-01236-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 01/31/2024] [Indexed: 04/18/2024]
Abstract
The frequency of errors upon decoding of messenger RNA by the bacterial ribosome is low, with one misreading event per 1 × 104 codons. In the universal genetic code, the AUN codon box specifies two amino acids, isoleucine and methionine. In bacteria and archaea, decoding specificity of the AUA and AUG codons relies on the wobble avoidance strategy that requires modification of C34 in the anticodon loop of isoleucine transfer RNAIleCAU (tRNAIleCAU). Bacterial tRNAIleCAU with 2-lysylcytidine (lysidine) at the wobble position deciphers AUA while avoiding AUG. Here we report cryo-electron microscopy structures of the Escherichia coli 70S ribosome complexed with elongation factor thermo unstable (EF-Tu) and isoleucine-tRNAIleLAU in the process of decoding AUA and AUG. Lysidine in tRNAIleLAU excludes AUG by promoting the formation of an unusual Hoogsteen purine-pyrimidine nucleobase geometry at the third position of the codon, weakening the interactions with the mRNA and destabilizing the EF-Tu ternary complex. Our findings elucidate the molecular mechanism by which tRNAIleLAU specifically decodes AUA over AUG.
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Affiliation(s)
- Mariia Yu Rybak
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - Matthieu G Gagnon
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA.
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.
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3
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Helena-Bueno K, Rybak MY, Ekemezie CL, Sullivan R, Brown CR, Dingwall C, Baslé A, Schneider C, Connolly JPR, Blaza JN, Csörgő B, Moynihan PJ, Gagnon MG, Hill CH, Melnikov SV. A new family of bacterial ribosome hibernation factors. Nature 2024; 626:1125-1132. [PMID: 38355796 PMCID: PMC10901736 DOI: 10.1038/s41586-024-07041-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 01/08/2024] [Indexed: 02/16/2024]
Abstract
To conserve energy during starvation and stress, many organisms use hibernation factor proteins to inhibit protein synthesis and protect their ribosomes from damage1,2. In bacteria, two families of hibernation factors have been described, but the low conservation of these proteins and the huge diversity of species, habitats and environmental stressors have confounded their discovery3-6. Here, by combining cryogenic electron microscopy, genetics and biochemistry, we identify Balon, a new hibernation factor in the cold-adapted bacterium Psychrobacter urativorans. We show that Balon is a distant homologue of the archaeo-eukaryotic translation factor aeRF1 and is found in 20% of representative bacteria. During cold shock or stationary phase, Balon occupies the ribosomal A site in both vacant and actively translating ribosomes in complex with EF-Tu, highlighting an unexpected role for EF-Tu in the cellular stress response. Unlike typical A-site substrates, Balon binds to ribosomes in an mRNA-independent manner, initiating a new mode of ribosome hibernation that can commence while ribosomes are still engaged in protein synthesis. Our work suggests that Balon-EF-Tu-regulated ribosome hibernation is a ubiquitous bacterial stress-response mechanism, and we demonstrate that putative Balon homologues in Mycobacteria bind to ribosomes in a similar fashion. This finding calls for a revision of the current model of ribosome hibernation inferred from common model organisms and holds numerous implications for how we understand and study ribosome hibernation.
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Affiliation(s)
| | - Mariia Yu Rybak
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | | | - Rudi Sullivan
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Charlotte R Brown
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | | | - Arnaud Baslé
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Claudia Schneider
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | | | - James N Blaza
- Department of Chemistry, University of York, York, UK
- York Structural Biology Laboratory, University of York, York, UK
- York Biomedical Research Institute, University of York, York, UK
| | - Bálint Csörgő
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, Hungary
| | | | - Matthieu G Gagnon
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, USA.
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA.
- Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
- Institute for Human Infections & Immunity, University of Texas Medical Branch, Galveston, TX, USA.
| | - Chris H Hill
- York Structural Biology Laboratory, University of York, York, UK.
- York Biomedical Research Institute, University of York, York, UK.
- Department of Biology, University of York, York, UK.
| | - Sergey V Melnikov
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.
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4
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Seely SM, Parajuli NP, De Tarafder A, Ge X, Sanyal S, Gagnon MG. Molecular basis of the pleiotropic effects by the antibiotic amikacin on the ribosome. Nat Commun 2023; 14:4666. [PMID: 37537169 PMCID: PMC10400623 DOI: 10.1038/s41467-023-40416-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 07/26/2023] [Indexed: 08/05/2023] Open
Abstract
Aminoglycosides are a class of antibiotics that bind to ribosomal RNA and exert pleiotropic effects on ribosome function. Amikacin, the semisynthetic derivative of kanamycin, is commonly used for treating severe infections with multidrug-resistant, aerobic Gram-negative bacteria. Amikacin carries the 4-amino-2-hydroxy butyrate (AHB) moiety at the N1 amino group of the central 2-deoxystreptamine (2-DOS) ring, which may confer amikacin a unique ribosome inhibition profile. Here we use in vitro fast kinetics combined with X-ray crystallography and cryo-EM to dissect the mechanisms of ribosome inhibition by amikacin and the parent compound, kanamycin. Amikacin interferes with tRNA translocation, release factor-mediated peptidyl-tRNA hydrolysis, and ribosome recycling, traits attributed to the additional interactions amikacin makes with the decoding center. The binding site in the large ribosomal subunit proximal to the 3'-end of tRNA in the peptidyl (P) site lays the groundwork for rational design of amikacin derivatives with improved antibacterial properties.
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Affiliation(s)
- Savannah M Seely
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Narayan P Parajuli
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124, Uppsala, Sweden
| | - Arindam De Tarafder
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124, Uppsala, Sweden
| | - Xueliang Ge
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124, Uppsala, Sweden
| | - Suparna Sanyal
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124, Uppsala, Sweden.
| | - Matthieu G Gagnon
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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5
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Basu RS, Sherman MB, Gagnon MG. Compact IF2 allows initiator tRNA accommodation into the P site and gates the ribosome to elongation. Nat Commun 2022; 13:3388. [PMID: 35697706 PMCID: PMC9192638 DOI: 10.1038/s41467-022-31129-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 06/02/2022] [Indexed: 11/09/2022] Open
Abstract
During translation initiation, initiation factor 2 (IF2) holds initiator transfer RNA (fMet-tRNAifMet) in a specific orientation in the peptidyl (P) site of the ribosome. Upon subunit joining IF2 hydrolyzes GTP and, concomitant with inorganic phosphate (Pi) release, changes conformation facilitating fMet-tRNAifMet accommodation into the P site and transition of the 70 S ribosome initiation complex (70S-IC) to an elongation-competent ribosome. The mechanism by which IF2 separates from initiator tRNA at the end of translation initiation remains elusive. Here, we report cryo-electron microscopy (cryo-EM) structures of the 70S-IC from Pseudomonas aeruginosa bound to compact IF2-GDP and initiator tRNA. Relative to GTP-bound IF2, rotation of the switch 2 α-helix in the G-domain bound to GDP unlocks a cascade of large-domain movements in IF2 that propagate to the distal tRNA-binding domain C2. The C2-domain relocates 35 angstroms away from tRNA, explaining how IF2 makes way for fMet-tRNAifMet accommodation into the P site. Our findings provide the basis by which IF2 gates the ribosome to the elongation phase.
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Affiliation(s)
- Ritwika S Basu
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Michael B Sherman
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Matthieu G Gagnon
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, 77555, USA.
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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6
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Seely SM, Gagnon MG. Mechanisms of ribosome recycling in bacteria and mitochondria: a structural perspective. RNA Biol 2022; 19:662-677. [PMID: 35485608 PMCID: PMC9067457 DOI: 10.1080/15476286.2022.2067712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
In all living cells, the ribosome translates the genetic information carried by messenger RNAs (mRNAs) into proteins. The process of ribosome recycling, a key step during protein synthesis that ensures ribosomal subunits remain available for new rounds of translation, has been largely overlooked. Despite being essential to the survival of the cell, several mechanistic aspects of ribosome recycling remain unclear. In eubacteria and mitochondria, recycling of the ribosome into subunits requires the concerted action of the ribosome recycling factor (RRF) and elongation factor G (EF-G). Recently, the conserved protein HflX was identified in bacteria as an alternative factor that recycles the ribosome under stress growth conditions. The homologue of HflX, the GTP-binding protein 6 (GTPBP6), has a dual role in mitochondrial translation by facilitating ribosome recycling and biogenesis. In this review, mechanisms of ribosome recycling in eubacteria and mitochondria are described based on structural studies of ribosome complexes.
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Affiliation(s)
- Savannah M Seely
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1019, USA
| | - Matthieu G Gagnon
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1019, USA.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-1019, USA.,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555-1019, USA.,Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas 77555, USA
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7
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Lin J, Zhou D, Steitz TA, Polikanov YS, Gagnon MG. Ribosome-Targeting Antibiotics: Modes of Action, Mechanisms of Resistance, and Implications for Drug Design. Annu Rev Biochem 2018; 87:451-478. [PMID: 29570352 DOI: 10.1146/annurev-biochem-062917-011942] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genetic information is translated into proteins by the ribosome. Structural studies of the ribosome and of its complexes with factors and inhibitors have provided invaluable information on the mechanism of protein synthesis. Ribosome inhibitors are among the most successful antimicrobial drugs and constitute more than half of all medicines used to treat infections. However, bacterial infections are becoming increasingly difficult to treat because the microbes have developed resistance to the most effective antibiotics, creating a major public health care threat. This has spurred a renewed interest in structure-function studies of protein synthesis inhibitors, and in few cases, compounds have been developed into potent therapeutic agents against drug-resistant pathogens. In this review, we describe the modes of action of many ribosome-targeting antibiotics, highlight the major resistance mechanisms developed by pathogenic bacteria, and discuss recent advances in structure-assisted design of new molecules.
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Affiliation(s)
- Jinzhong Lin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China;
| | - Dejian Zhou
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China;
| | - Thomas A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA; .,Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.,Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520, USA
| | - Yury S Polikanov
- Department of Biological Sciences, and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60607, USA;
| | - Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA; .,Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520, USA.,Current affiliation: Department of Microbiology and Immunology, and Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555, USA;
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8
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Gagnon MG, Roy RN, Lomakin IB, Florin T, Mankin AS, Steitz TA. Structures of proline-rich peptides bound to the ribosome reveal a common mechanism of protein synthesis inhibition. Nucleic Acids Res 2016; 44:2439-50. [PMID: 26809677 PMCID: PMC4797290 DOI: 10.1093/nar/gkw018] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/07/2016] [Indexed: 12/20/2022] Open
Abstract
With bacterial resistance becoming a serious threat to global public health, antimicrobial peptides (AMPs) have become a promising area of focus in antibiotic research. AMPs are derived from a diverse range of species, from prokaryotes to humans, with a mechanism of action that often involves disruption of the bacterial cell membrane. Proline-rich antimicrobial peptides (PrAMPs) are instead actively transported inside the bacterial cell where they bind and inactivate specific targets. Recently, it was reported that some PrAMPs, such as Bac71 -35, oncocins and apidaecins, bind and inactivate the bacterial ribosome. Here we report the crystal structures of Bac71 -35, Pyrrhocoricin, Metalnikowin and two oncocin derivatives, bound to the Thermus thermophilus 70S ribosome. Each of the PrAMPs blocks the peptide exit tunnel of the ribosome by simultaneously occupying three well characterized antibiotic-binding sites and interferes with the initiation step of translation, thereby revealing a common mechanism of action used by these PrAMPs to inactivate protein synthesis. Our study expands the repertoire of PrAMPs and provides a framework for designing new-generation therapeutics.
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Affiliation(s)
- Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA
| | - Raktim N Roy
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA
| | - Ivan B Lomakin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Tanja Florin
- Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, Chicago, IL 60607-7173, USA
| | - Alexander S Mankin
- Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, Chicago, IL 60607-7173, USA
| | - Thomas A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA
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9
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Affiliation(s)
- Ivan B Lomakin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA.,Howard Hughes Medical Institute, Yale University, New Haven, Connecticut, USA
| | - Thomas A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA.,Howard Hughes Medical Institute, Yale University, New Haven, Connecticut, USA
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10
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Roy RN, Lomakin IB, Gagnon MG, Steitz TA. The mechanism of inhibition of protein synthesis by the proline-rich peptide oncocin. Nat Struct Mol Biol 2015; 22:466-9. [PMID: 25984972 PMCID: PMC4456192 DOI: 10.1038/nsmb.3031] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 04/15/2015] [Indexed: 12/30/2022]
Affiliation(s)
- Raktim N Roy
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
| | - Ivan B Lomakin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Matthieu G Gagnon
- 1] Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA. [2] Howard Hughes Medical Institute, Yale University, New Haven, Connecticut, USA
| | - Thomas A Steitz
- 1] Department of Chemistry, Yale University, New Haven, Connecticut, USA. [2] Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA. [3] Howard Hughes Medical Institute, Yale University, New Haven, Connecticut, USA
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11
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Lin J, Gagnon MG, Bulkley D, Steitz TA. Conformational changes of elongation factor G on the ribosome during tRNA translocation. Cell 2015; 160:219-27. [PMID: 25594181 DOI: 10.1016/j.cell.2014.11.049] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/09/2014] [Accepted: 11/21/2014] [Indexed: 12/29/2022]
Abstract
The universally conserved GTPase elongation factor G (EF-G) catalyzes the translocation of tRNA and mRNA on the ribosome after peptide bond formation. Despite numerous studies suggesting that EF-G undergoes extensive conformational rearrangements during translocation, high-resolution structures exist for essentially only one conformation of EF-G in complex with the ribosome. Here, we report four atomic-resolution crystal structures of EF-G bound to the ribosome programmed in the pre- and posttranslocational states and to the ribosome trapped by the antibiotic dityromycin. We observe a previously unseen conformation of EF-G in the pretranslocation complex, which is independently captured by dityromycin on the ribosome. Our structures provide insights into the conformational space that EF-G samples on the ribosome and reveal that tRNA translocation on the ribosome is facilitated by a structural transition of EF-G from a compact to an elongated conformation, which can be prevented by the antibiotic dityromycin.
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Affiliation(s)
- Jinzhong Lin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA
| | - David Bulkley
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA; Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA
| | - Thomas A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA; Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA.
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12
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Abstract
Elongation factor 4 (EF4/LepA) is a highly conserved guanosine triphosphatase translation factor. It was shown to promote back-translocation of tRNAs on posttranslocational ribosome complexes and to compete with elongation factor G for interaction with pretranslocational ribosomes, inhibiting the elongation phase of protein synthesis. Here, we report a crystal structure of EF4-guanosine diphosphate bound to the Thermus thermophilus ribosome with a P-site tRNA at 2.9 angstroms resolution. The C-terminal domain of EF4 reaches into the peptidyl transferase center and interacts with the acceptor stem of the peptidyl-tRNA in the P site. The ribosome is in an unusual state of ratcheting with the 30S subunit rotated clockwise relative to the 50S subunit, resulting in a remodeled decoding center. The structure is consistent with EF4 functioning either as a back-translocase or a ribosome sequester.
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Affiliation(s)
- Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA. Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA
| | - Jinzhong Lin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - David Bulkley
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA. Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA
| | - Thomas A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA. Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA. Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA.
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13
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Gagnon MG, Seetharaman SV, Bulkley D, Steitz TA. Structural basis for the rescue of stalled ribosomes: structure of YaeJ bound to the ribosome. Science 2012; 335:1370-2. [PMID: 22422986 DOI: 10.1126/science.1217443] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In bacteria, the hybrid transfer-messenger RNA (tmRNA) rescues ribosomes stalled on defective messenger RNAs (mRNAs). However, certain gram-negative bacteria have evolved proteins that are capable of rescuing stalled ribosomes in a tmRNA-independent manner. Here, we report a 3.2 angstrom-resolution crystal structure of the rescue factor YaeJ bound to the Thermus thermophilus 70S ribosome in complex with the initiator tRNA(i)(fMet) and a short mRNA. The structure reveals that the C-terminal tail of YaeJ functions as a sensor to discriminate between stalled and actively translating ribosomes by binding in the mRNA entry channel downstream of the A site between the head and shoulder of the 30S subunit. This allows the N-terminal globular domain to sample different conformations, so that its conserved GGQ motif is optimally positioned to catalyze the hydrolysis of peptidyl-tRNA. This structure gives insights into the mechanism of YaeJ function and provides a basis for understanding how it rescues stalled ribosomes.
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Affiliation(s)
- Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
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14
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Abstract
To understand how the nucleotide sequence of ribosomal RNA determines its tertiary structure, we developed a new approach for identification of those features of rRNA sequence that are responsible for formation of different short- and long-range interactions. The approach is based on the co-analysis of several examples of a particular recurrent RNA motif. For different cases of the motif, we design combinatorial gene libraries in which equivalent nucleotide positions are randomized. Through in vivo expression of the designed libraries we select those variants that provide for functional ribosomes. Then, analysis of the nucleotide sequences of the selected clones would allow us to determine the sequence constraints imposed on each case of the motif. The constraints shared by all cases are interpreted as providing for the integrity of the motif, while those ones specific for individual cases would enable the motif to fit into the particular structural context. Here we demonstrate the validity of this approach for three examples of the so-called along-groove packing motif found in different parts of ribosomal RNA.
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Affiliation(s)
- Matthieu G Gagnon
- Département de Biochimie, Université de Montréal, Montréal, CP 6128, Succursale Centre-Ville, QC H3C 3J7, Canada
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15
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Abstract
Here, we present a new recurrent RNA arrangement, the so-called adenosine wedge (A-wedge), which is found in three places of the ribosomal RNA in both ribosomal subunits. The arrangement has a hierarchical structure, consisting of elements previously described as recurrent motifs, namely, the along-groove packing motif, the A-minor and the hook-turn. Within the A-wedge, these elements are involved in different types of cause-effect relationships, providing together for the particular tertiary structure of the motif.
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Affiliation(s)
- Matthieu G Gagnon
- Departement de Biochimie, Universite de Montreal, Montreal, Quebec H3C 3J7, Canada
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16
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Abstract
The along-groove packing motif is a quasi-reciprocal arrangement of two RNA double helices in which a backbone of each helix is closely packed within the minor groove of the other helix. At the center of the inter-helix contact, a GU base pair in one helix packs against a Watson-Crick base pair in the other helix. Here, based on in vivo selection from a combinatorial gene library of 16 S rRNA and on functional characterization of the selected clones, we demonstrate that the normal ribosome performance requires that helices 3 and 12 be closely packed. In some clones the Watson-Crick and GU base pairs exchange in their positions between the two helices, which affects neither the quality of the helix packing, nor the ribosome function. On the other hand, perturbations in the close packing usually lead to a substantial drop in the ribosome activity. The functionality of the clones containing such perturbations may depend on the presence of particular elements in the vicinity of the area of contact between helices 3 and 12. Such cases do not exist in natural 16 S rRNA, and their selection enriches our knowledge of the constraints imposed on the structure of ribosomal RNA in functional ribosomes.
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Affiliation(s)
- Matthieu G Gagnon
- Département de Biochimie, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
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17
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Bélanger F, Gagnon MG, Steinberg SV, Cunningham PR, Brakier-Gingras L. Study of the Functional Interaction of the 900 Tetraloop of 16S Ribosomal RNA with Helix 24 within the Bacterial Ribosome. J Mol Biol 2004; 338:683-93. [PMID: 15099737 DOI: 10.1016/j.jmb.2004.03.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Revised: 03/08/2004] [Accepted: 03/10/2004] [Indexed: 10/26/2022]
Abstract
The 900 tetraloop that caps helix 27 of 16S ribosomal RNA (rRNA) is amongst the most conserved regions of rRNA. This tetraloop forms a GNRA motif that docks into the minor groove of three base-pairs at the bottom of helix 24 of 16S rRNA in the 30S subunit. Both the tetraloop and its receptor in helix 24 contact the 23S rRNA, forming the intersubunit bridge B2c. Here, we investigated the interaction between the 900 tetraloop and its receptor by genetic complementation. We used a specialized ribosome system in combination with an in vivo instant evolution approach to select mutations in helix 24 compensating for a mutation in the 900 tetraloop (A900G) that severely decreases ribosomal activity, impairing subunit association and translational fidelity. We selected two mutants where the G769-C810 base-pair of helix 24 was substituted with either U-A or C x A. When these mutations in helix 24 were investigated in the context of a wild-type 900 tetraloop, the C x A but not the U-A mutation severely impaired ribosome activity, interfering with subunit association and decreasing translational fidelity. In the presence of the A900G mutation, both mutations in helix 24 increased the ribosome activity to the same extent. Subunit association and translational fidelity were increased to the same level. Computer modeling was used to analyze the effect of the mutations in helix 24 on the interaction between the tetraloop and its receptor. This study demonstrates the functional importance of the interaction between the 900 tetraloop and helix 24.
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Affiliation(s)
- François Bélanger
- Département de Biochimie, Université de Montréal, Montréal, Qué., Canada H3T 1J4
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18
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Abstract
A new RNA structural motif consisting of two double helices closely packed via minor grooves is found in many places in the ribosome structure. The packing requires that a GU base pair in one helix be packed against a Watson-Crick pair in the other helix. Two such motifs mediate the interaction of the P- and E-tRNA with the large ribosomal subunit. Analysis of the particular positions of these two motifs in view of the available data on occupancy of tRNA-binding sites and structural changes in the ribosome during the elongation cycle suggests a distinct role for each motif in tRNA translocation.
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19
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Gareau R, Brisson GR, Chénard C, Gagnon MG, Richalet JP, Audran M. Discrimination possible entre entraînement en altitude et dopage à l'érythropoïétine. Sci Sports 1995. [DOI: 10.1016/0765-1597(96)89530-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Gareau R, Brisson GR, Chénard C, Gagnon MG, Audran M. Total fibrin and fibrinogen degradation products in urine: a possible probe to detect illicit users of the physical-performance enhancer erythropoietin? Horm Res 1995; 44:189-92. [PMID: 8522282 DOI: 10.1159/000184623] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Erythropoietin (Epo) represents for some athletes the ultimate tool to gain an edge over their peer competitors. Underground information indicates that its usage is spreading at an epidemic pace since no analytical technique is yet available to detect its utilization. We hereby report observations obtained from analysis of urine specimens collected from top-level athletes after international-calibre competitions. Possible Epo misuse was evaluated by the measurement of urine total degradation products (TDPs), excretory fragments attributed by Sakakibara et al. to the fibrinolytic action of Epo. Markedly elevated urine TDP levels were measured in more than 13% of the 76 top-level athletes evaluated in this study. Analyses of urine specimens from a control hockey player group and from out-of-competition resting subjects indicate that the urine TDP content is not significantly influenced by exercise per se. Solid confirmation of TDP measurement as a sound probe to detect illicit Epo users should come from controlled studies with concomitant administration of Epo.
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Affiliation(s)
- R Gareau
- Haematology Laboratory, Université du Québec à Trois-Rivières, Montréal, Canada
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21
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Gareau R, Gagnon MG, Thellend C, Chénard C, Audran M, Chanal JL, Ayotte C, Brisson GR. Transferrin soluble receptor: a possible probe for detection of erythropoietin abuse by athletes. Horm Metab Res 1994; 26:311-2. [PMID: 7927199 DOI: 10.1055/s-2007-1001692] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- R Gareau
- Haematology Laboratory, University of Québec at Trois-Rivières, Canada
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22
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Gareau R, Gagnon MG, Ayotte C, Chénard C, Brisson GR. rHuEPO increases urinary excretion of fibrin degradation products in haemodialysed patients. Thromb Haemost 1993; 70:373-4. [PMID: 8236152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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23
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Dallaire L, Gagnon MG. [Semiquantitative study of amniotic fluid amino acids in relation to length of pregnancy and maternal plasma and urine amino acid levels]. Union Med Can 1971; 100:1116-21. [PMID: 5561234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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24
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Gagnon MG, Doray BH, Ayotte RA. [Amniocentesis, spectrophotometry and intrauterine transfusions in fetal erythroblastosis]. Union Med Can 1968; 97:1014-24. [PMID: 5674548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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25
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Gagnon MG. [Recent considerations on the Rh factor in obstetric practice]. Union Med Can 1966; 95:1408-12. [PMID: 5996222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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