1
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Matsumoto A. Dynamic analysis of ribosome by a movie made from many three-dimensional electron-microscopy density maps. Biophys Physicobiol 2019; 16:108-113. [PMID: 31131181 PMCID: PMC6530885 DOI: 10.2142/biophysico.16.0_108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 03/12/2019] [Indexed: 12/01/2022] Open
Abstract
The atomic models of the 70S ribosome including the bound molecules were built from many 3D-EM density maps. The positions and conformations of the bound molecules were determined by fitting them to the regions in the density maps which remained after fitting the 70S ribosome. Then, using these atomic models, a movie for the elongation cycle was made. For determining the sequential order in which the models appeared in the movie, the knowledge about the bound molecules and the ratchet angles were used. The movie revealed several interesting points which were not apparent from each density map, suggesting the usefulness of a movie made from many 3D-EM density maps.
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2
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Li W, Agrawal RK. Joachim Frank's Binding with the Ribosome. Structure 2019; 27:411-419. [PMID: 30595455 PMCID: PMC11062599 DOI: 10.1016/j.str.2018.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/09/2018] [Accepted: 11/15/2018] [Indexed: 01/03/2023]
Abstract
With recent technological advancements, single-particle cryogenic electron microscopy (cryo-EM) is now the technique of choice to study structure and function of biological macromolecules at near-atomic resolution. Many single-particle EM reconstruction methods necessary for these advances were pioneered by Joachim Frank, and were optimized using the ribosome as a benchmark specimen. In doing so, he made several landmark contributions to the understanding of the structure and function of ribosomes. These include the first 3D visualization of ribosome-bound transfer RNAs, the first experimentally derived structures of the primary complexes formed during the bacterial translation elongation cycle, and the critical ribosomal conformational transitions required for translation. Over the years, his laboratory studied many important functional complexes of the ribosome from both eubacterial and eukaryotic systems, including ribosomes from pathogenic organisms. This article presents a brief account of the contributions made by Joachim Frank to the ribosome field.
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Affiliation(s)
- Wen Li
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
| | - Rajendra K Agrawal
- Division of Translational Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA; Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA.
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3
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Kurita D, Miller MR, Muto A, Buskirk AR, Himeno H. Rejection of tmRNA·SmpB after GTP hydrolysis by EF-Tu on ribosomes stalled on intact mRNA. RNA (NEW YORK, N.Y.) 2014; 20:1706-1714. [PMID: 25246654 PMCID: PMC4201823 DOI: 10.1261/rna.045773.114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 07/18/2014] [Indexed: 06/03/2023]
Abstract
Messenger RNAs lacking a stop codon trap ribosomes at their 3' ends, depleting the pool of ribosomes available for protein synthesis. In bacteria, a remarkable quality control system rescues and recycles stalled ribosomes in a process known as trans-translation. Acting as a tRNA, transfer-messenger RNA (tmRNA) is aminoacylated, delivered by EF-Tu to the ribosomal A site, and accepts the nascent polypeptide. Translation then resumes on a reading frame within tmRNA, encoding a short peptide tag that targets the nascent peptide for degradation by proteases. One unsolved issue in trans-translation is how tmRNA and its protein partner SmpB preferentially recognize stalled ribosomes and not actively translating ones. Here, we examine the effect of the length of the 3' extension of mRNA on each step of trans-translation by pre-steady-state kinetic methods and fluorescence polarization binding assays. Unexpectedly, EF-Tu activation and GTP hydrolysis occur rapidly regardless of the length of the mRNA, although the peptidyl transfer to tmRNA decreases as the mRNA 3' extension increases and the tmRNA·SmpB binds less tightly to the ribosome with an mRNA having a long 3' extension. From these results, we conclude that the tmRNA·SmpB complex dissociates during accommodation due to competition between the downstream mRNA and the C-terminal tail for the mRNA channel. Rejection of the tmRNA·SmpB complex during accommodation is reminiscent of the rejection of near-cognate tRNA from the ribosome in canonical translation.
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Affiliation(s)
- Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | - Mickey R Miller
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - Akira Muto
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | - Allen R Buskirk
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - Hyouta Himeno
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
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4
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Ranaei-Siadat E, Mérigoux C, Seijo B, Ponchon L, Saliou JM, Bernauer J, Sanglier-Cianférani S, Dardel F, Vachette P, Nonin-Lecomte S. In vivo tmRNA protection by SmpB and pre-ribosome binding conformation in solution. RNA (NEW YORK, N.Y.) 2014; 20:1607-20. [PMID: 25135523 PMCID: PMC4174442 DOI: 10.1261/rna.045674.114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 06/15/2014] [Indexed: 06/03/2023]
Abstract
TmRNA is an abundant RNA in bacteria with tRNA and mRNA features. It is specialized in trans-translation, a translation rescuing system. We demonstrate that its partner protein SmpB binds the tRNA-like region (TLD) in vivo and chaperones the fold of the TLD-H2 region. We use an original approach combining the observation of tmRNA degradation pathways in a heterologous system, the analysis of the tmRNA digests by MS and NMR, and co-overproduction assays of tmRNA and SmpB. We study the conformation in solution of tmRNA alone or in complex with one SmpB before ribosome binding using SAXS. Our data show that Mg(2+) drives compaction of the RNA structure and that, in the absence of Mg(2+), SmpB has a similar effect albeit to a lesser extent. Our results show that tmRNA is intrinsically structured in solution with identical topology to that observed on complexes on ribosomes which should facilitate its subsequent recruitment by the 70S ribosome, free or preloaded with one SmpB molecule.
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Affiliation(s)
- Ehsan Ranaei-Siadat
- CNRS-UMR 8015, Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie, 75270 Paris Cedex 06, France Université Paris Descartes, LCRB, Faculté de Pharmacie, 75270 Paris Cedex 06, France
| | - Cécile Mérigoux
- Université Paris-Sud, IBBMC, UMR8619, 91405 Orsay, France CNRS, 91405 Orsay, France
| | - Bili Seijo
- CNRS-UMR 8015, Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie, 75270 Paris Cedex 06, France Université Paris Descartes, LCRB, Faculté de Pharmacie, 75270 Paris Cedex 06, France
| | - Luc Ponchon
- CNRS-UMR 8015, Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie, 75270 Paris Cedex 06, France Université Paris Descartes, LCRB, Faculté de Pharmacie, 75270 Paris Cedex 06, France
| | - Jean-Michel Saliou
- CNRS, IPHC-LSMBO, Université Louis Pasteur Bât, 67087 Strasbourg, France
| | - Julie Bernauer
- AMIB, INRIA Saclay-Île de France, 91120 Palaiseau, France LIX, CNRS UMR 7161, École Polytechnique, 91120 Palaiseau, France
| | | | - Fréderic Dardel
- CNRS-UMR 8015, Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie, 75270 Paris Cedex 06, France Université Paris Descartes, LCRB, Faculté de Pharmacie, 75270 Paris Cedex 06, France
| | - Patrice Vachette
- Université Paris-Sud, IBBMC, UMR8619, 91405 Orsay, France CNRS, 91405 Orsay, France
| | - Sylvie Nonin-Lecomte
- CNRS-UMR 8015, Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie, 75270 Paris Cedex 06, France Université Paris Descartes, LCRB, Faculté de Pharmacie, 75270 Paris Cedex 06, France
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5
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Wower IK, Zwieb C, Wower J. Requirements for resuming translation in chimeric transfer-messenger RNAs of Escherichia coli and Mycobacterium tuberculosis. BMC Mol Biol 2014; 15:19. [PMID: 25220282 PMCID: PMC4236655 DOI: 10.1186/1471-2199-15-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 06/18/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trans-translation is catalyzed by ribonucleprotein complexes composed of SmpB protein and transfer-messenger RNA. They release stalled ribosomes from truncated mRNAs and tag defective proteins for proteolytic degradation. Comparative sequence analysis of bacterial tmRNAs provides considerable insights into their secondary structures in which a tRNA-like domain and an mRNA-like region are connected by a variable number of pseudoknots. Progress toward understanding the molecular mechanism of trans-translation is hampered by our limited knowledge about the structure of tmRNA:SmpB complexes. RESULTS Complexes consisting of M. tuberculosis tmRNA and E. coli SmpB tag truncated proteins poorly in E. coli. In contrast, the tagging activity of E. coli tmRNA is well supported by M. tuberculosis SmpB that is expressed in E. coli. To investigate this incompatibility, we constructed 12 chimeric tmRNA molecules composed of structural features derived from both E. coli and M. tuberculosis. Our studies demonstrate that replacing the hp5-pk2-pk3-pk4 segment of E. coli tmRNA with the equivalent segment of M. tuberculosis tmRNA has no significant effect on the tagging efficiency of chimeric tmRNAs in the presence of E. coli SmpB. Replacing either helices 2b-2d, the single-stranded part of the ORF, pk1, or residues 79-89 of E. coli tmRNA with the equivalent features of M. tuberculosis tmRNA yields chimeric tmRNAs that are tagged at 68 to 88 percent of what is observed with E. coli tmRNA. Exchanging segments composed of either pk1 and the single-stranded segment upstream of the ORF or helices 2b-2d and pk1 results in markedly impaired tagging activity. CONCLUSION Our observations demonstrate the existence of functionally important but as yet uncharacterized structural constraints in the segment of tmRNA that connects its TLD to the ORF used for resuming translation. As trans-translation is important for the survival of M. tuberculosis, our work provides a new target for pharmacological intervention against multidrug-resistant tuberculosis.
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6
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Giudice E, Macé K, Gillet R. Trans-translation exposed: understanding the structures and functions of tmRNA-SmpB. Front Microbiol 2014; 5:113. [PMID: 24711807 PMCID: PMC3968760 DOI: 10.3389/fmicb.2014.00113] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/05/2014] [Indexed: 11/13/2022] Open
Abstract
Ribosome stalling is a serious issue for cell survival. In bacteria, the primary rescue system is trans-translation, performed by tmRNA and its protein partner small protein B (SmpB). Since its discovery almost 20 years ago, biochemical, genetic, and structural studies have paved the way to a better understanding of how this sophisticated process takes place at the cellular and molecular levels. Here we describe the molecular details of trans-translation, with special mention of recent cryo-electron microscopy and crystal structures that have helped explain how the huge tmRNA-SmpB complex targets and delivers stalled ribosomes without interfering with canonical translation.
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Affiliation(s)
- Emmanuel Giudice
- Translation and Folding Team, Université de Rennes 1, CNRS UMR 6290 IGDR Rennes, France
| | - Kevin Macé
- Translation and Folding Team, Université de Rennes 1, CNRS UMR 6290 IGDR Rennes, France
| | - Reynald Gillet
- Translation and Folding Team, Université de Rennes 1, CNRS UMR 6290 IGDR Rennes, France ; Institut Universitaire de France France
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7
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Himeno H, Kurita D, Muto A. Mechanism of trans-translation revealed by in vitro studies. Front Microbiol 2014; 5:65. [PMID: 24600445 PMCID: PMC3929946 DOI: 10.3389/fmicb.2014.00065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 02/04/2014] [Indexed: 11/28/2022] Open
Abstract
tmRNA is a bacterial small RNA having a structure resembling the upper half of tRNA and its 3′ end accepts alanine followed by binding to EF-Tu like tRNA. Instead of lacking a lower half of the cloverleaf structure including the anticodon, tmRNA has a short coding sequence for tag-peptide that serves as a target of cellular proteases. An elaborate coordination of two functions as tRNA and mRNA facilitates an irregular translation termed trans-translation: a single polypeptide is synthesized from two mRNA molecules. It allows resumption of translation stalled on a truncated mRNA, producing a chimeric polypeptide comprising the C-terminally truncated polypeptide derived from truncated mRNA and the C-terminal tag-peptide encoded by tmRNA. Trans-translation promotes recycling of the stalled ribosomes in the cell, and the resulting C-terminally tagged polypeptide is preferentially degraded by cellular proteases. Biochemical studies using in vitro trans-translation systems together with structural studies have unveiled the molecular mechanism of trans-translation, during which the upper and lower halves of tRNA are mimicked by the tRNA-like structure of tmRNA and a tmRNA-specific binding protein called SmpB, respectively. They mimic not only the tRNA structure but also its behavior perhaps at every step of the trans-translation process in the ribosome. Furthermore, the C-terminal tail of SmpB, which is unstructured in solution, occupies the mRNA path in the ribosome to play a crucial role in trans-translation, addressing how tmRNA·SmpB recognizes the ribosome stalled on a truncated mRNA.
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Affiliation(s)
- Hyouta Himeno
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University Hirosaki, Japan ; RNA Research Center, Hirosaki University Hirosaki, Japan
| | - Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University Hirosaki, Japan ; RNA Research Center, Hirosaki University Hirosaki, Japan
| | - Akira Muto
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University Hirosaki, Japan
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8
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Giudice E, Gillet R. The task force that rescues stalled ribosomes in bacteria. Trends Biochem Sci 2013; 38:403-11. [PMID: 23820510 DOI: 10.1016/j.tibs.2013.06.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 05/28/2013] [Accepted: 06/03/2013] [Indexed: 11/29/2022]
Abstract
In bacteria, the main quality control mechanism for rescuing ribosomes that have arrested during translation is trans-translation, performed by transfer-mRNA (tmRNA) associated with small protein B (SmpB). Intriguingly, this very elegant mechanism is not always necessary to maintain cell viability, suggesting the existence of alternatives. Other rescue systems have recently been discovered, revealing a far more complicated story than expected. These include the alternative ribosome rescue factors ArfA and ArfB, the elongation factors EF4 and EF-P, the peptidyl-tRNA hydrolase Pth, and several protein synthesis factors. These discoveries make it possible to describe a large network of factors dedicated to ribosome rescue, thus ensuring cell survival during stresses that induce ribosome stalling.
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Affiliation(s)
- Emmanuel Giudice
- Translation and Folding Team, Université de Rennes 1, UMR CNRS 6290 IGDR, Campus de Beaulieu 35042 Rennes cedex, France
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9
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Weis F, Bron P, Giudice E, Rolland JP, Thomas D, Felden B, Gillet R. tmRNA-SmpB: a journey to the centre of the bacterial ribosome. EMBO J 2010; 29:3810-8. [PMID: 20953161 DOI: 10.1038/emboj.2010.252] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 09/21/2010] [Indexed: 11/09/2022] Open
Abstract
Ribosomes mediate protein synthesis by decoding the information carried by messenger RNAs (mRNAs) and catalysing peptide bond formation between amino acids. When bacterial ribosomes stall on incomplete messages, the trans-translation quality control mechanism is activated by the transfer-messenger RNA bound to small protein B (tmRNA-SmpB ribonucleoprotein complex). Trans-translation liberates the stalled ribosomes and triggers degradation of the incomplete proteins. Here, we present the cryo-electron microscopy structures of tmRNA-SmpB accommodated or translocated into stalled ribosomes. Two atomic models for each state are proposed. This study reveals how tmRNA-SmpB crosses the ribosome and how, as the problematic mRNA is ejected, the tmRNA resume codon is placed onto the ribosomal decoding site by new contacts between SmpB and the nucleotides upstream of the tag-encoding sequence. This provides a structural basis for the transit of the large tmRNA-SmpB complex through the ribosome and for the means by which the tmRNA internal frame is set for translation to resume.
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Affiliation(s)
- Félix Weis
- Université de Rennes, UMR CNRS Equipe Structure et Dynamique des Macromolécules, Rennes, France
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10
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Barends S, Kraal B, van Wezel GP. The tmRNA-tagging mechanism and the control of gene expression: a review. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 2:233-46. [PMID: 21957008 DOI: 10.1002/wrna.48] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The tmRNA-mediated trans-translation system is a unique quality control system in eubacteria that combines translational surveillance with the rescue of stalled ribosomes. During trans-translation, the chimeric tmRNA molecule--which acts as both tRNA and mRNA--is delivered to the ribosomal A site by a ribonucleoprotein complex of SmpB and EF-Tu-GTP, allowing the stalled ribosome to switch template and resume translation on a small coding sequence inside the tmRNA molecule. As a result, the aberrant protein becomes tagged by a sequence that is a target for proteolytic degradation. Thus, the system elegantly combines ribosome recycling with a clean-up function when triggered by truncated transcripts or rare codons. In addition, recent observations point to a specific regulation of the translation of a small number of genes by tmRNA-mediated inhibition or stimulation. In this review, we discuss the most prominent biochemical and structural aspects of trans-translation and then focus on the specific role of tmRNA in stress management and cell-cycle control of morphologically complex bacteria.
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Affiliation(s)
- Sharief Barends
- ProteoNic, Niels Bohrweg 11-13, 2333 CA Leiden, The Netherlands
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11
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Kurita D, Muto A, Himeno H. Role of the C-terminal tail of SmpB in the early stage of trans-translation. RNA (NEW YORK, N.Y.) 2010; 16:980-990. [PMID: 20348441 PMCID: PMC2856891 DOI: 10.1261/rna.1916610] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 02/11/2010] [Indexed: 05/29/2023]
Abstract
Trans-translation relieves a stalled translation on the bacterial ribosome by transfer-messenger RNA (tmRNA) with the help of SmpB, an essential cofactor of tmRNA. Here, we examined the role of the unstructured C-terminal tail of SmpB using an in vitro trans-translation system. It was found that truncation of the C-terminal tail or substitution of tryptophan residue at 147 in the middle of the C-terminal tail affected the activity in the early stage of trans-translation. Our investigations also revealed that the C-terminal tail is not required for the events until GTP is hydrolyzed by EF-Tu in complex with tmRNA-SmpB. A synthetic peptide corresponding to the C-terminal tail of SmpB inhibited peptidyl-transfer of alanyl-tmRNA and A-site binding of SmpB, but not GTP hydrolysis. These results suggest that the C-terminal tail has a role in the step of accommodation of alanyl-tmRNA-SmpB into the A-site. Directed hydroxyl radical probing indicated that tryptophan residue at 147 is located just downstream of the decoding center in the mRNA path when SmpB is in the A-site.
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MESH Headings
- Amino Acid Substitution
- Base Sequence
- Binding Sites/genetics
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Guanosine Triphosphate/metabolism
- Kinetics
- Models, Biological
- Models, Molecular
- Mutagenesis, Site-Directed
- Peptide Elongation Factor Tu/metabolism
- Peptide Fragments/chemistry
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Protein Biosynthesis
- Protein Structure, Tertiary
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Amino Acyl/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Ribosomes/metabolism
- Sequence Deletion
- Tryptophan/chemistry
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Affiliation(s)
- Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
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12
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Matsumoto A, Ishida H. Global conformational changes of ribosome observed by normal mode fitting for 3D Cryo-EM structures. Structure 2010; 17:1605-1613. [PMID: 20004164 DOI: 10.1016/j.str.2009.09.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 09/25/2009] [Accepted: 09/27/2009] [Indexed: 11/30/2022]
Abstract
Many three-dimensional density maps of 70S ribosome at various functional states are available now in the Electron Microscopy DataBank at EBI. We used our new flexible-fitting approach to systematically analyze these maps to reveal the global conformational differences between the EM structures. Large-scale ratchet-like deformations were observed in an EM structure of the initiation complex and in some EM structures bound with EFG, RF3, and RRF. In most of them, the L1 stalk, which interacts with the tRNA molecule at the E site of ribosome and is considered to be involved in the release of the tRNA, was in "the blocking state" for the E-tRNA. Furthermore, we found that the EM structures bound with EFG or RRF were aligned in the conformational space, suggesting that the large-scale conformational changes of the 70S ribosome bound with these factors occur along a specific pathway in a concerted manner.
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Affiliation(s)
- Atsushi Matsumoto
- Center for Computational Science and Engineering, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan; Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan.
| | - Hisashi Ishida
- Center for Computational Science and Engineering, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan; Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
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13
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Weis F, Bron P, Rolland JP, Thomas D, Felden B, Gillet R. Accommodation of tmRNA-SmpB into stalled ribosomes: a cryo-EM study. RNA (NEW YORK, N.Y.) 2010; 16:299-306. [PMID: 20038631 PMCID: PMC2811659 DOI: 10.1261/rna.1757410] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 10/27/2009] [Indexed: 05/28/2023]
Abstract
In eubacteria, translation of defective messenger RNAs (mRNAs) produces truncated polypeptides that stall on the ribosome. A quality control mechanism referred to as trans-translation is performed by transfer-messenger RNA (tmRNA), a specialized RNA acting as both a tRNA and an mRNA, associated with small protein B (SmpB). So far, a clear view of the structural movements of both the protein and RNA necessary to perform accommodation is still lacking. By using a construct containing the tRNA-like domain as well as the extended helix H2 of tmRNA, we present a cryo-electron microscopy study of the process of accommodation. The structure suggests how tmRNA and SmpB move into the ribosome decoding site after the release of EF-Tu.GDP. While two SmpB molecules are bound per ribosome in a preaccommodated state, our results show that during accommodation the SmpB protein interacting with the small subunit decoding site stays in place while the one interacting with the large subunit moves away. Relative to canonical translation, an additional movement is observed due to the rotation of H2. This suggests that the larger movement required to resume translation on a tmRNA internal open reading frame starts during accommodation.
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Affiliation(s)
- Felix Weis
- Universite de Rennes 1, INSERM U835, Laboratoire de Biochimie Pharmaceutique, 35043 Rennes Cedex, France
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14
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Bugaeva EY, Surkov S, Golovin AV, Ofverstedt LG, Skoglund U, Isaksson LA, Bogdanov AA, Shpanchenko OV, Dontsova OA. Structural features of the tmRNA-ribosome interaction. RNA (NEW YORK, N.Y.) 2009; 15:2312-2320. [PMID: 19861420 PMCID: PMC2779675 DOI: 10.1261/rna.1584209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 09/08/2009] [Indexed: 05/28/2023]
Abstract
Trans-translation is a process which switches the synthesis of a polypeptide chain encoded by a nonstop messenger RNA to the mRNA-like domain of a transfer-messenger RNA (tmRNA). It is used in bacterial cells for rescuing the ribosomes arrested during translation of damaged mRNA and directing this mRNA and the product polypeptide for degradation. The molecular basis of this process is not well understood. Earlier, we developed an approach that allowed isolation of tmRNA-ribosomal complexes arrested at a desired step of tmRNA passage through the ribosome. We have here exploited it to examine the tmRNA structure using chemical probing and cryo-electron microscopy tomography. Computer modeling has been used to develop a model for spatial organization of the tmRNA inside the ribosome at different stages of trans-translation.
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MESH Headings
- Base Sequence
- Cryoelectron Microscopy
- Escherichia coli/chemistry
- Escherichia coli/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Biosynthesis
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Bacterial/ultrastructure
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Messenger/ultrastructure
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA, Transfer/ultrastructure
- Ribosomes/chemistry
- Ribosomes/metabolism
- Ribosomes/ultrastructure
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Affiliation(s)
- Elizaveta Y Bugaeva
- Belozersky Institute, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
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15
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Watts T, Cazier D, Healey D, Buskirk A. SmpB contributes to reading frame selection in the translation of transfer-messenger RNA. J Mol Biol 2009; 391:275-81. [PMID: 19540849 DOI: 10.1016/j.jmb.2009.06.037] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 06/09/2009] [Accepted: 06/16/2009] [Indexed: 11/26/2022]
Abstract
Transfer-messenger RNA (tmRNA) acts first as a tRNA and then as an mRNA template to rescue stalled ribosomes in eubacteria. Together with its protein partner, SmpB (small protein B), tmRNA enters stalled ribosomes and transfers an Ala residue to the growing polypeptide chain. A remarkable step then occurs: the ribosome leaves the stalled mRNA and resumes translation using tmRNA as a template, adding a short peptide tag that destines the aborted protein for destruction. Exactly how the ribosome switches templates, resuming translation on tmRNA in the proper reading frame, remains unknown. Within the tmRNA sequence itself, five nucleotides (U85AGUC) immediately upstream of the first codon appear to direct frame selection. In particular, mutation of the conserved A86 results in severe loss of function both in vitro and in vivo. The A86C mutation causes translation to resume exclusively in the +1 frame. Several candidate binding partners for this upstream sequence have been identified in vitro. Using a genetic selection for tmRNA activity in Escherichia coli, we identified mutations in the SmpB protein that restore the function of A86C tmRNA in vivo. The SmpB mutants increase tagging in the normal reading frame and reduce tagging in the +1 frame. These results demonstrate that SmpB is functionally linked with the sequence upstream of the tmRNA template; both contribute to reading frame selection on tmRNA.
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Affiliation(s)
- Talina Watts
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
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16
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Ribosome hijacking: a role for small protein B during trans-translation. EMBO Rep 2009; 10:160-5. [PMID: 19132006 DOI: 10.1038/embor.2008.243] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 10/30/2008] [Accepted: 11/26/2008] [Indexed: 11/08/2022] Open
Abstract
Tight recognition of codon-anticodon pairings by the ribosome ensures the accuracy and fidelity of protein synthesis. In eubacteria, translational surveillance and ribosome rescue are performed by the 'tmRNA-SmpB' system (transfer messenger RNA-small protein B). Remarkably, entry and accommodation of aminoacylated-tmRNA into stalled ribosomes occur without a codon-anticodon interaction but in the presence of SmpB. Here, we show that within a stalled ribosome, SmpB interacts with the three universally conserved bases G530, A1492 and A1493 that form the 30S subunit decoding centre, in which canonical codon-anticodon pairing occurs. The footprints at positions A1492 and A1493 of a small decoding centre, as well as on a set of conserved SmpB amino acids, were identified by nuclear magnetic resonance. Mutants at these residues display the same growth defects as for DeltasmpB strains. The SmpB protein has functional and structural similarities with initiation factor 1, and is proposed to be a functional mimic of the pairing between a codon and an anticodon.
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17
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Metzinger L, Hallier M, Felden B. The highest affinity binding site of small protein B on transfer messenger RNA is outside the tRNA domain. RNA (NEW YORK, N.Y.) 2008; 14:1761-1772. [PMID: 18648069 PMCID: PMC2525949 DOI: 10.1261/rna.1185808] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Accepted: 05/17/2008] [Indexed: 05/26/2023]
Abstract
Eubacterial ribosomes stalled on defective mRNAs are released through a mechanism referred to as trans-translation, depending on the coordinated actions of small protein B (SmpB) and transfer messenger RNA (tmRNA). A series of tmRNA variants with deletions in each structural domain were produced. Their structures were monitored by enzymatic and chemical probes in vitro, in the presence and absence of SmpB. Dissociation constants between these RNAs and SmpB from Aquifex aeolicus were derived by surface plasmon resonance (SPR) combined with filter binding assays. Three independent experimental evidences, including filter binding assays, SPR, and concentration titrations of the RNA-protein reactivity changes toward structural probes, indicate that the binding site that has the highest affinity for the protein is located outside the tRNA domain, upstream of the internal tag. The minimal tmRNA fragment that contains this high affinity site for SmpB, and also contains another site of lower affinity, includes the tag reading frame and three downstream pseudoknots that form a ring structure in solution.
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Affiliation(s)
- Laurent Metzinger
- Biochimie Pharmaceutique, Inserm U835, Upres JE 2311, Université de Rennes 1, France
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18
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Miller MR, Healey DW, Robison SG, Dewey JD, Buskirk AR. The role of upstream sequences in selecting the reading frame on tmRNA. BMC Biol 2008; 6:29. [PMID: 18590561 PMCID: PMC2481249 DOI: 10.1186/1741-7007-6-29] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 06/30/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND tmRNA acts first as a tRNA and then as an mRNA to rescue stalled ribosomes in eubacteria. Two unanswered questions about tmRNA function remain: how does tmRNA, lacking an anticodon, bypass the decoding machinery and enter the ribosome? Secondly, how does the ribosome choose the proper codon to resume translation on tmRNA? According to the -1 triplet hypothesis, the answer to both questions lies in the unique properties of the three nucleotides upstream of the first tmRNA codon. These nucleotides assume an A-form conformation that mimics the codon-anticodon interaction, leading to recognition by the decoding center and choice of the reading frame. The -1 triplet hypothesis is important because it is the most credible model in which direct binding and recognition by the ribosome sets the reading frame on tmRNA. RESULTS Conformational analysis predicts that 18 triplets cannot form the correct structure to function as the -1 triplet of tmRNA. We tested the tmRNA activity of all possible -1 triplet mutants using a genetic assay in Escherichia coli. While many mutants displayed reduced activity, our findings do not match the predictions of this model. Additional mutagenesis identified sequences further upstream that are required for tmRNA function. An immunoblot assay for translation of the tmRNA tag revealed that certain mutations in U85, A86, and the -1 triplet sequence result in improper selection of the first codon and translation in the wrong frame (-1 or +1) in vivo. CONCLUSION Our findings disprove the -1 triplet hypothesis. The -1 triplet is not required for accommodation of tmRNA into the ribosome, although it plays a minor role in frame selection. Our results strongly disfavor direct ribosomal recognition of the upstream sequence, instead supporting a model in which the binding of a separate ligand to A86 is primarily responsible for frame selection.
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Affiliation(s)
- Mickey R Miller
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
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19
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Bugaeva EY, Shpanchenko OV, Felden B, Isaksson LA, Dontsova OA. One SmpB molecule accompanies tmRNA during its passage through the ribosomes. FEBS Lett 2008; 582:1532-6. [PMID: 18396159 DOI: 10.1016/j.febslet.2008.03.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 03/19/2008] [Accepted: 03/21/2008] [Indexed: 11/17/2022]
Abstract
tmRNA and SmpB are the main participants of trans-translation, a process which rescues the ribosome blocked during translation of non-stop mRNA. While a one-to-one stoichiometry of tmRNA to the ribosome is generally accepted, the number of SmpB molecules in the complex is still under question. We have isolated tmRNA-ribosome complexes blocked at different steps of the tmRNA path through the ribosome and analyzed the stoichiometry of the complexes. Ribosome, tmRNA and SmpB were found in equimolar amount in the tmRNA-ribosome complexes stopped at the position of the 2nd, 4th, 5th or the 11th codons of the coding part of the tmRNA.
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Affiliation(s)
- Elizaveta Y Bugaeva
- Belozersky Institute, Build. A, Moscow State University, Moscow 119992, Russia
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20
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Abstract
Small protein B (SmpB) is a requisite component of the transfer messenger RNA (tmRNA)-mediated bacterial translational quality control system known as trans-translation. The initial binding of tmRNA and its subsequent accommodation into the ribosomal A-site are activities intimately linked to SmpB protein function. From a mechanistic perspective, two key unanswered questions that require further investigation are: 1) what constitutes a stalled ribosome recognition complex and 2) does SmpB pre-bind ribosomes to recruit tmRNA. We have assessed, both in vivo and in vitro, the nature and stability of free SmpB interactions with stalled ribosomes and examined whether these interactions are functionally relevant. We present evidence to demonstrate that interaction of free SmpB with ribosomes is salt sensitive and significantly more labile than interaction of the SmpB.tmRNA complex with ribosomes. Upon dissociation of 70 S ribosomes SmpB partitions primarily with tmRNA rather than ribosomal subunits. This finding is consistent with biochemical and structural data demonstrating that tmRNA is the high-affinity binding partner of SmpB. Moreover, we show that under normal physiological conditions roughly similar numbers of SmpB and tmRNA molecules are present in cells. Our investigations also reveal that upon induction of a nonstop mRNA, SmpB is enriched in stalled ribosome fractions only in the presence of tmRNA. Based on these findings, we conclude that SmpB does not pre-bind stalled ribosome and that functional SmpB-stalled ribosome interactions require tmRNA. We propose that a 1:1:1 complex of SmpB.tmRNA.EF-Tu(GTP) recognizes and binds a stalled ribosome to initiate trans-translation.
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Affiliation(s)
| | - A. Wali Karzai
- Department of Biochemistry and Cell Biology
- Center for Infectious Diseases of Stony Brook University Stony Brook, NY 11794 USA
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21
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Kurita D, Sasaki R, Muto A, Himeno H. Interaction of SmpB with ribosome from directed hydroxyl radical probing. Nucleic Acids Res 2007; 35:7248-55. [PMID: 17959652 PMCID: PMC2175365 DOI: 10.1093/nar/gkm677] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To add a tag-peptide for degradation to the nascent polypeptide in a stalled ribosome, an unusual translation called trans-translation is facilitated by transfer-messenger RNA (tmRNA) having an upper half of the tRNA structure and the sequence encoding the tag-peptide except the first alanine. During this event, tmRNA enters the vacant A-site of the stalled ribosome without a codon-anticodon interaction, but with a protein factor SmpB. Here, we studied the sites and modes of binding of SmpB to the ribosome by directed hydroxyl radical probing from Fe(II) tethered to SmpB variants. It revealed two SmpB-binding sites, A-site and P-site, on the ribosome. Each SmpB can be superimposed on the lower half of tRNA behaving in translation. The sites of cleavages from Fe(II) tethered to the C-terminal residues of A-site SmpB are aligned along the mRNA path towards the downstream tunnel, while those of P-site SmpB are found almost exclusively around the region of the codon-anticodon interaction in the P-site. We propose a new model of trans-translation in that the C-terminal tail of SmpB initially recognizes the decoding region and the mRNA path free of mRNA by mimicking mRNA.
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Affiliation(s)
- Daisuke Kurita
- Department of Biochemistry and Biotechnology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
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22
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Konno T, Kurita D, Takada K, Muto A, Himeno H. A functional interaction of SmpB with tmRNA for determination of the resuming point of trans-translation. RNA (NEW YORK, N.Y.) 2007; 13:1723-31. [PMID: 17698641 PMCID: PMC1986810 DOI: 10.1261/rna.604907] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In trans-translation, transfer-messenger RNA (tmRNA), possessing a dual function as a tRNA and an mRNA, relieves a stalled translation on the ribosome with the help of SmpB. Here, we established an in vitro system using Escherichia coli translation and trans-translation factors to evaluate two steps of trans-translation, peptidyl transfer from peptidyl-tRNA to alanyl-tmRNA and translation of the resume codon on tmRNA. Using this system, the effects of several mutations upstream of the tag-encoding region on tmRNA were examined. These mutations affected translation of the resume codon rather than peptidyl transfer, and one of them, A84U/U85G, caused a shift of the resume codon by -1. We also found that U(85) is protected from chemical modification by SmpB. In the A84U/U85G mutant, the base of protection was shifted from 85 to 84. Another mutation, A86U, which caused a shift of the resume codon by +1, shifted the base of protection from 85 to 86. The protection at 85 was suppressed by a mutation in the tRNA-like domain critical to SmpB binding. These results suggest that SmpB serves to bridge two separate domains of tmRNA to determine the initial codon for tag-translation. A mutant SmpB with a truncation of the unstructured C-terminal tail failed to promote peptidyl transfer, although it still protected U(85) from chemical modification.
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Affiliation(s)
- Takayuki Konno
- Department of Biochemistry and Biotechnology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
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23
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Abstract
Small regulatory RNAs have been identified in a wide range of organisms, where they modify mRNA stability, translation or protein function. Small RNA regulators (sRNAs) either pair with mRNA targets or modify protein activities. Here we discuss current knowledge of the various proteins that interact with RNA regulators and review the physiologic implications of sRNA-protein complexes in DNA, RNA and protein metabolism, as well as in RNA and protein quality control in prokaryotes. Proteins that interact with the sRNAs can possess catalytic activity, induce conformational changes of the sRNA, or be sequestered by the sRNA to prevent the action of the protein.
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Affiliation(s)
- Christophe Pichon
- INSERM U835, Upres JE2311, Biochimie Pharmaceutique, Université de Rennes 1, Rennes, France
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24
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Abstract
Protein synthesis is an efficient and vital mechanism mediated by the ribosomes. In all living organisms, it allows an accurate correspondence between the genetic information and the newly synthesized polypeptides. The process of translation needs accurate quality-control systems to ensure the correct readout of the genetic data at the cellular level. Among them, bacteria did develop a specific mechanism referred to as "trans-translation", ensuring the recycling of stalled translating ribosomes and the degradation of incomplete nascent proteins when incomplete messenger RNAs (mRNAs) are translated. tmRNA (transfer messenger RNA) and SmpB (small protein B) are the main components of that process. Recent biochemical, genetic and structural data provide insights on how the tmRNA-SmpB complex accomplishes its duty, allowing a deeper understanding of the intricate links between trans-translation, bacterial survival and virulence.
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Affiliation(s)
- Reynald Gillet
- Université de Rennes I, Inserm U835, UPRES JE 2311, Biochimie Pharmaceutique, 2, avenue du Professeur-Léon-Bernard, 35043 Rennes, France.
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25
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Saguy M, Gillet R, Skorski P, Hermann-Le Denmat S, Felden B. Ribosomal protein S1 influences trans-translation in vitro and in vivo. Nucleic Acids Res 2007; 35:2368-76. [PMID: 17392345 PMCID: PMC1874662 DOI: 10.1093/nar/gkm100] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
When the bacterial ribosome stalls on a truncated mRNA, transfer–messenger RNA (tmRNA) acts initially as a transfer RNA (tRNA) and then as a messenger RNA (mRNA) to rescue the ribosome and add a peptide tag to the nascent polypeptide that targets it for degradation. Ribosomal protein S1 binds tmRNA but its functional role in this process has remained elusive. In this report, we demonstrate that, in vitro, S1 is dispensable for the tRNA-like role of tmRNA but is essential for its mRNA function. Increasing or decreasing the amount of protein S1 in vivo reduces the overall amount of trans-translated proteins. Also, a truncated S1 protein impaired for ribosome binding can still trigger protein tagging, suggesting that S1 interacts with tmRNA outside the ribosome to keep it in an active state. Overall, these results demonstrate that S1 has a role in tmRNA-mediated tagging that is distinct from its role during canonical translation.
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Affiliation(s)
- Matthieu Saguy
- Université de Rennes 1, UPRES 2311, Inserm U835, Biochimie Pharmaceutique, 2 Avenue du Prof. Léon Bernard, 35000 Rennes, France and Laboratoire de Génétique Moléculaire, CNRS UMR8541, Ecole Normale Supérieure, 46 Rue d’Ulm, 75230 Paris, France
| | - Reynald Gillet
- Université de Rennes 1, UPRES 2311, Inserm U835, Biochimie Pharmaceutique, 2 Avenue du Prof. Léon Bernard, 35000 Rennes, France and Laboratoire de Génétique Moléculaire, CNRS UMR8541, Ecole Normale Supérieure, 46 Rue d’Ulm, 75230 Paris, France
| | - Patricia Skorski
- Université de Rennes 1, UPRES 2311, Inserm U835, Biochimie Pharmaceutique, 2 Avenue du Prof. Léon Bernard, 35000 Rennes, France and Laboratoire de Génétique Moléculaire, CNRS UMR8541, Ecole Normale Supérieure, 46 Rue d’Ulm, 75230 Paris, France
| | - Sylvie Hermann-Le Denmat
- Université de Rennes 1, UPRES 2311, Inserm U835, Biochimie Pharmaceutique, 2 Avenue du Prof. Léon Bernard, 35000 Rennes, France and Laboratoire de Génétique Moléculaire, CNRS UMR8541, Ecole Normale Supérieure, 46 Rue d’Ulm, 75230 Paris, France
| | - Brice Felden
- Université de Rennes 1, UPRES 2311, Inserm U835, Biochimie Pharmaceutique, 2 Avenue du Prof. Léon Bernard, 35000 Rennes, France and Laboratoire de Génétique Moléculaire, CNRS UMR8541, Ecole Normale Supérieure, 46 Rue d’Ulm, 75230 Paris, France
- *To whom correspondence should be addressed. +33 2 23 23 48 5133 2 23 23 44 56
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