1
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Antika TR, Nazilah KR, Chrestella DJ, Wang TL, Tseng YK, Wang SC, Hsu HL, Wang SW, Chuang TH, Pan HC, Horng JC, Wang CC. Sequence-specific targeting of Caenorhabditis elegans C-Ala to the D-loop of tRNA Ala. J Biol Chem 2023; 299:105149. [PMID: 37567477 PMCID: PMC10485164 DOI: 10.1016/j.jbc.2023.105149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 08/13/2023] Open
Abstract
Alanyl-tRNA synthetase retains a conserved prototype structure throughout its biology. Nevertheless, its C-terminal domain (C-Ala) is highly diverged and has been shown to play a role in either tRNA or DNA binding. Interestingly, we discovered that Caenorhabditis elegans cytoplasmic C-Ala (Ce-C-Alac) robustly binds both ligands. How Ce-C-Alac targets its cognate tRNA and whether a similar feature is conserved in its mitochondrial counterpart remain elusive. We show that the N- and C-terminal subdomains of Ce-C-Alac are responsible for DNA and tRNA binding, respectively. Ce-C-Alac specifically recognized the conserved invariant base G18 in the D-loop of tRNAAla through a highly conserved lysine residue, K934. Despite bearing little resemblance to other C-Ala domains, C. elegans mitochondrial C-Ala robustly bound both tRNAAla and DNA and maintained targeting specificity for the D-loop of its cognate tRNA. This study uncovers the underlying mechanism of how C. elegans C-Ala specifically targets the D-loop of tRNAAla.
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Affiliation(s)
- Titi Rindi Antika
- Department of Life Sciences, National Central University, Taoyuan, Taiwan
| | | | | | - Tzu-Ling Wang
- Graduate Institute of Mathematics and Science Education, National Tsing Hua University, Hsinchu City, Taiwan
| | - Yi-Kuan Tseng
- Graduate Institute of Statistics, National Central University, Taoyuan, Taiwan
| | - Sun-Chong Wang
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan
| | - Hsin-Ling Hsu
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli, Taiwan
| | - Shao-Win Wang
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli, Taiwan
| | - Tsung-Hsien Chuang
- Immunology Research Center, National Health Research Institutes, Miaoli, Taiwan
| | - Hung-Chuan Pan
- Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Jia-Cherng Horng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Chien-Chia Wang
- Department of Life Sciences, National Central University, Taoyuan, Taiwan.
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2
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Tamilmaran N, Sankaranarayanan R, Selvakumar A S P, Munavar MH. Horizontal transfer of domains in ssrA gene among Enterobacteriaceae. Genes Cells 2021; 26:541-550. [PMID: 33971069 DOI: 10.1111/gtc.12869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 11/29/2022]
Abstract
The tmRNA (transfer messenger RNA), encoded by ssrA gene, is involved in rescuing of stalled ribosomes by a process called trans-translation. Additionally, regions of the ssrA gene (coding for tmRNA) were reported to serve as integration sites for various bacteriophages. Though variations in ssrA genes were reported, their functional relevance is less studied. In this study, we investigated the horizontal gene transfer (HGT) of ssrA among the members of Enterobacteriaceae. This was done by predicting recombination signals in ssrA gene (belonging to Enterobacteriaceae) using RDP5 (Recombination Detection Program 5). Our results revealed 7 recombination signals in ssrA gene belonging to different species. We further showed that the recombination signals were more in the domains present in the 3' end than 5' end of tmRNA. Of note, the mRNA region was reported in many recombination signals. Further, members belonging to genera Yersinia, Erwinia, Dickeya and Enterobacter were highly represented in the recombination signals. Sequence analysis revealed the presence of integration sites for different class of bacteriophages in ssrA gene. The locations of phage recognition sites are comparable with recombination signals. Taken together, our results revealed a diverse nature of HGT and recombination which possibly due to transduction mediated by phages.
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Affiliation(s)
- Nagarajan Tamilmaran
- Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, India
| | | | | | - M Hussain Munavar
- Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, India
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3
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Post-Transcriptional Modifications of Conserved Nucleotides in the T-Loop of tRNA: A Tale of Functional Convergent Evolution. Genes (Basel) 2021; 12:genes12020140. [PMID: 33499018 PMCID: PMC7912444 DOI: 10.3390/genes12020140] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/30/2022] Open
Abstract
The high conservation of nucleotides of the T-loop, including their chemical identity, are hallmarks of tRNAs from organisms belonging to the three Domains of Life. These structural characteristics allow the T-loop to adopt a peculiar intraloop conformation able to interact specifically with other conserved residues of the D-loop, which ultimately folds the mature tRNA in a unique functional canonical L-shaped architecture. Paradoxically, despite the high conservation of modified nucleotides in the T-loop, enzymes catalyzing their formation depend mostly on the considered organism, attesting for an independent but convergent evolution of the post-transcriptional modification processes. The driving force behind this is the preservation of a native conformation of the tRNA elbow that underlies the various interactions of tRNA molecules with different cellular components.
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4
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Rae CD, Gordiyenko Y, Ramakrishnan V. How a circularized tmRNA moves through the ribosome. Science 2019; 363:740-744. [PMID: 30765567 DOI: 10.1126/science.aav9370] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 01/22/2019] [Indexed: 01/05/2023]
Abstract
During trans-translation, transfer-messenger RNA (tmRNA) and small protein B (SmpB) together rescue ribosomes stalled on a truncated mRNA and tag the nascent polypeptide for degradation. We used cryo-electron microscopy to determine the structures of three key states of the tmRNA-SmpB-ribosome complex during trans translation at resolutions of 3.7 to 4.4 angstroms. The results show how tmRNA and SmpB act specifically on stalled ribosomes and how the circularized complex moves through the ribosome, enabling translation to switch from the old defective message to the reading frame on tmRNA.
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Affiliation(s)
- Christopher D Rae
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, England, UK
| | - Yuliya Gordiyenko
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, England, UK
| | - V Ramakrishnan
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, England, UK.
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5
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Schudoma C. It's a loop world - single strands in RNA as structural and functional elements. Biomol Concepts 2015; 2:171-81. [PMID: 25962027 DOI: 10.1515/bmc.2011.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 03/25/2011] [Indexed: 01/31/2023] Open
Abstract
Unpaired regions in RNA molecules - loops - are centrally involved in defining the characteristic three-dimensional (3D) architecture of RNAs and are of high interest in RNA engineering and design. Loops adopt diverse, but specific conformations stabilised by complex tertiary structural interactions that provide structural flexibility to RNA structures that would otherwise not be possible if they only consisted of the rigid A-helical shapes usually formed by canonical base pairing. By participating in sequence-non-local contacts, they furthermore contribute to stabilising the overall fold of RNA molecules. Interactions between RNAs and other nucleic acids, proteins, or small molecules are also generally mediated by RNA loop structures. Therefore, the function of an RNA molecule is generally dependent on its loops. Examples include intermolecular interactions between RNAs as part of the microRNA processing pathways, ribozymatic activity, or riboswitch-ligand interactions. Bioinformatics approaches have been successfully applied to the identification of novel RNA structural motifs including loops, local and global RNA 3D structure prediction, and structural and conformational analysis of RNAs and have contributed to a better understanding of the sequence-structure-function relationships in RNA loops.
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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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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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8
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Nameki N, Someya T, Okano S, Suemasa R, Kimoto M, Hanawa-Suetsugu K, Terada T, Shirouzu M, Hirao I, Takaku H, Himeno H, Muto A, Kuramitsu S, Yokoyama S, Kawai G. Interaction analysis between tmRNA and SmpB from Thermus thermophilus. J Biochem 2009; 138:729-39. [PMID: 16428302 DOI: 10.1093/jb/mvi180] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Small protein B, SmpB, is a tmRNA-specific binding protein essential for trans-translation. We examined the interaction between SmpB and tmRNA from Thermus thermophilus, using biochemical and NMR methods. Chemical footprinting analyses using full-length tmRNA demonstrated that the sites protected upon SmpB binding are located exclusively in the tRNA-like domain (TLD) of tmRNA. To clarify the SmpB binding sites, we constructed several segments derived from TLD. Optical biosensor interaction analyses and melting profile analyses with mutational studies showed that SmpB efficiently binds to only a 30-nt segment that forms a stem and loop, with the 5' and 3' extensions composed of the D-loop and variable-loop analogues. The conserved sequences, 16UCGA and 319GAC, in the extensions are responsible for the SmpB binding. These results agree with the those visualized by the cocrystal structure of TLD and SmpB from Aquifex aeolicus. In addition, NMR chemical shift mapping analyses, using the 30-nt segment and (15)N-labeled SmpB, revealed the characteristic RNA binding mode. The hydrogen bond pattern around beta2 changes, with the Gly in beta2, which acts as a hinge, showing the largest chemical shift change. It appears that SmpB undergoes structural changes indicating an induced fit upon binding to the specific region of TLD.
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Affiliation(s)
- Nobukazu Nameki
- Department of Industrial Chemistry, Faculty of Engineering, Chiba Institute of Technology, Chiba 275-0016
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9
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Abstract
The trans-translation mechanism is a key component of multiple quality control pathways in bacteria that ensure proteins are synthesized with high fidelity in spite of challenges such as transcription errors, mRNA damage, and translational frameshifting. trans-Translation is performed by a ribonucleoprotein complex composed of tmRNA, a specialized RNA with properties of both a tRNA and an mRNA, and the small protein SmpB. tmRNA-SmpB interacts with translational complexes stalled at the 3' end of an mRNA to release the stalled ribosomes and target the nascent polypeptides and mRNAs for degradation. In addition to quality control pathways, some genetic regulatory circuits use trans-translation to control gene expression. Diverse bacteria require trans-translation when they execute large changes in their genetic programs, including responding to stress, pathogenesis, and differentiation.
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Affiliation(s)
- Kenneth C Keiler
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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10
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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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11
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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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12
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Abstract
The tmRNA system performs translational surveillance and ribosome rescue in all eubacteria and some eukaryotic organelles. This system intervenes when ribosomes read to the 3' end of an mRNA or pause at internal codons with subsequent mRNA cleavage. A complex of alanyl-tmRNA (which functions as a tRNA and mRNA), SmpB protein, and EF-TucGTP binds stalled ribosomes, the nascent polypeptide is transferred to the alanine on tmRNA, and translation switches from the original message to a short tmRNA open reading frame (ORF) that encodes a degradation tag. Translation of the ORF and normal termination releases the tagged polypeptide for degradation and permits disassembly and recycling of ribosomal subunits for new rounds of protein synthesis. Structural and biochemical studies suggest mechanisms that keep tmRNA from interrupting normal translation and target ribosomes stalled with very short 3' mRNA extensions. Additional biological roles of tmRNA include stress management and the regulation of transcriptional circuits.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Macromolecular Substances
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Open Reading Frames
- Peptide Elongation Factor Tu/metabolism
- Protein Biosynthesis
- Protein Conformation
- RNA Stability
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA-Binding Proteins/metabolism
- Ribosomes/metabolism
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Affiliation(s)
- Sean D Moore
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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13
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Dulebohn D, Choy J, Sundermeier T, Okan N, Karzai AW. Trans-translation: the tmRNA-mediated surveillance mechanism for ribosome rescue, directed protein degradation, and nonstop mRNA decay. Biochemistry 2007; 46:4681-93. [PMID: 17397189 DOI: 10.1021/bi6026055] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The accurate flow of genetic information from DNA to RNA to protein is essential for all living organisms. An astonishing array of quality-assurance mechanisms have evolved to ensure that high degree of fidelity is maintained at every stage of this process. One of the most fascinating quality-control mechanisms involves tmRNA, also known as SsrA or 10Sa RNA. tmRNA is a versatile and highly conserved bacterial molecule endowed with the combined structural and functional properties of both a tRNA and a mRNA. The tmRNA system orchestrates three key biological functions: (1) recognition and rescue of ribosomes stalled on aberrant mRNAs, (2) disposal of the causative defective mRNAs, and (3) addition of a degradation tag to ribosome-associated protein fragments for directed proteolysis. Although not essential in Escherichia coli, tmRNA activity is essential for bacterial survival under adverse conditions and for virulence in some, and perhaps all, pathogenic bacteria. Recent evidence suggests that in addition to its quality-control function the tmRNA system might also play a key regulatory role in certain physiological pathways. This review will focus on recent advances in our understanding of the structural properties, mechanistic details, and physiological significance of this unique RNA and its principal protein partners.
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Affiliation(s)
- Daniel Dulebohn
- Department of Biochemistry and Cell Biology and The Center for Infectious Diseases, Stony Brook University, Stony Brook, New York 11794, USA
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14
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Shimizu Y, Ueda T. SmpB triggers GTP hydrolysis of elongation factor Tu on ribosomes by compensating for the lack of codon-anticodon interaction during trans-translation initiation. J Biol Chem 2006; 281:15987-96. [PMID: 16601123 DOI: 10.1074/jbc.m512165200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial tmRNA rescues ribosomes that stall because of defective mRNAs via the trans-translation process. Although entry of the charged transfer messenger RNA (tmRNA) into the ribosome proceeded in the absence of elongation factor (EF-Tu) and in the presence of EF-Tu and the antibiotic kirromycin, evidence was found for the involvement of EF-Tu in trans-translation initiation. The polyalanine synthesis system attained by using a tmRNA variant consisting of only the tRNA-like domain revealed that it was completely dependent on the presence of SmpB and greatly enhanced by EF-Tu and EF-G. Actually, ribosome-dependent GTPase activity of EF-Tu was stimulated by the addition of SmpB and tmRNA but independently of template mRNA, demonstrating that SmpB compensates for the lack of codon-anticodon interaction during the first step of the trans-translation initiation. Based on these results, we suggest that SmpB structurally mimics the anticodon arm of tRNA and elicits GTP hydrolysis of EF-Tu upon tmRNA accommodation in the A site of the ribosome.
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Affiliation(s)
- Yoshihiro Shimizu
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, the University of Tokyo, FSB401, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba Prefecture 277-8562, Japan
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15
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Andersen ES, Rosenblad MA, Larsen N, Westergaard JC, Burks J, Wower IK, Wower J, Gorodkin J, Samuelsson T, Zwieb C. The tmRDB and SRPDB resources. Nucleic Acids Res 2006; 34:D163-8. [PMID: 16381838 PMCID: PMC1347504 DOI: 10.1093/nar/gkj142] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Maintained at the University of Texas Health Science Center at Tyler, Texas, the tmRNA database (tmRDB) is accessible at the URL http://psyche.uthct.edu/dbs/tmRDB/tmRDB.html with mirror sites located at Auburn University, Auburn, Alabama (http://www.ag.auburn.edu/mirror/tmRDB/) and the Royal Veterinary and Agricultural University, Denmark (http://tmrdb.kvl.dk/). The signal recognition particle database (SRPDB) at http://psyche.uthct.edu/dbs/SRPDB/SRPDB.html is mirrored at http://srpdb.kvl.dk/ and the University of Goteborg (http://bio.lundberg.gu.se/dbs/SRPDB/SRPDB.html). The databases assist in investigations of the tmRNP (a ribonucleoprotein complex which liberates stalled bacterial ribosomes) and the SRP (a particle which recognizes signal sequences and directs secretory proteins to cell membranes). The curated tmRNA and SRP RNA alignments consider base pairs supported by comparative sequence analysis. Also shown are alignments of the tmRNA-associated proteins SmpB, ribosomal protein S1, alanyl-tRNA synthetase and Elongation Factor Tu, as well as the SRP proteins SRP9, SRP14, SRP19, SRP21, SRP54 (Ffh), SRP68, SRP72, cpSRP43, Flhf, SRP receptor (alpha) and SRP receptor (beta). All alignments can be easily examined using a new exploratory browser. The databases provide links to high-resolution structures and serve as depositories for structures obtained by molecular modeling.
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Affiliation(s)
| | - Magnus Alm Rosenblad
- Department of Medical Biochemistry, Goteborg UniversityBox 440, SE-405 30 Goteborg, Sweden
- SWEGENE Bioinformatics, Goteborg UniversityBox 413, SE-405 30 Goteborg, Sweden
| | - Niels Larsen
- Danish Genome InstituteGustav Wieds vej 10 C, DK-8000 Aarhus C, Denmark
| | - Jesper Cairo Westergaard
- Department of Natural Sciences, The Royal Veterinary and Agricultural UniversityThorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Jody Burks
- Department of Animal Sciences, Auburn UniversityAuburn, AL 36849-5415, USA
| | - Iwona K. Wower
- Department of Animal Sciences, Auburn UniversityAuburn, AL 36849-5415, USA
| | - Jacek Wower
- Department of Animal Sciences, Auburn UniversityAuburn, AL 36849-5415, USA
| | - Jan Gorodkin
- Center for Bioinformatics and Division of Genetics, IBHV, The Royal Veterinary and Agricultural UniversityGroennegaardsvej 3, 1870 Frederiksberg C, Denmark
| | - Tore Samuelsson
- Department of Medical Biochemistry, Goteborg UniversityBox 440, SE-405 30 Goteborg, Sweden
| | - Christian Zwieb
- Department of Molecular Biology, The University of Texas Health Science Center at Tyler11937 US Highway 271, Tyler, TX 75708-3154, USA
- To whom correspondence should be addressed. Tel: +1 903 877 7689; Fax: +1 903 877 5731;
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16
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Sundermeier TR, Dulebohn DP, Cho HJ, Karzai AW. A previously uncharacterized role for small protein B (SmpB) in transfer messenger RNA-mediated trans-translation. Proc Natl Acad Sci U S A 2005; 102:2316-21. [PMID: 15699355 PMCID: PMC549014 DOI: 10.1073/pnas.0409694102] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SsrA is a versatile RNA molecule found in all bacteria that functions as both a tRNA and an mRNA. SsrA rescues ribosomes stalled on damaged mRNAs and directs the tagging and degradation of their aberrant protein products. Small protein B (SmpB) is required for all known activities of SsrA. The two known functions of SmpB are binding SsrA RNA and promoting stable association of the SmpB.SsrA complex with 70S ribosomes. Using mutational analysis and biochemical experiments, we have discovered a previously uncharacterized SmpB function. This function is required for a step in the tagging process downstream of SsrA binding and ribosome association but before transpeptidation of the SsrA-linked alanine and establishment of the SsrA reading frame. Our results clearly demonstrate that residues in the C-terminal tail of SmpB confer a hitherto unrevealed function that is essential for trans-translation. Based on these results, we propose that upon binding stalled ribosomes, the unstructured C-terminal tail of SmpB acquires contacts that are critical for productive accommodation of SsrA into the ribosomal A site.
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Affiliation(s)
- Thomas R Sundermeier
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
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17
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Abstract
Transfer-messenger RNA (tmRNA, or SsrA), found in all eubacteria, has both transfer and messenger RNA activity. Relieving ribosome stalling by a process called trans-translation, tmRNAala enters the ribosome and adds its aminoacylated alanine to the nascent polypeptide. The original mRNA is released and tmRNA becomes the template for translation of a 10-amino-acid tag that signals for proteolytic degradation. Although essential in a few bacterial species, tmRNA is nonessential in Escherichia coli and many other bacteria. Proteins known to be associated with tmRNA include SmpB, ribosomal protein S1, RNase R, and phosphoribosyl pyrophosphate. SmpB, having no other known function, is essential for tmRNA activity. trans-translation operates within ribosomes stalled both at the end of truncated mRNAs and at rare codons and some natural termination sites. Both the release of stalled ribosomes and the subsequent degradation of tagged proteins are important consequences of trans-translation.
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Affiliation(s)
- Jeffrey H Withey
- Unit for Lab Animal Medicine, University of Michigan Medical School, 104 ARF, Ann Arbor, Michigan 48109-0614, USA.
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Gaudin C, Nonin-Lecomte S, Tisné C, Corvaisier S, Bordeau V, Dardel F, Felden B. The tRNA-like domains of E coli and A.aeolicus transfer-messenger RNA: structural and functional studies. J Mol Biol 2003; 331:457-71. [PMID: 12888352 DOI: 10.1016/s0022-2836(03)00760-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Transfer-messenger RNA (tmRNA, 10Sa RNA or ssrA) acts to rescue stalled bacterial ribosomes while encoding a peptide tag added trans-translationally to the nascent peptide, targeting it for proteolysis. The understanding at molecular level of this ubiquitous quality control system in eubacteria requires structural information. Here, we describe the purification and structural analysis of a functional fragment of both Aquifex aeolicus and Escherichia coli tmRNA, recapitulating their tRNA-like domain, which were expressed in vivo from synthetic genes. Both recombinant RNA are correctly processed at both 5' and 3' ends and are produced in quantities suitable for structural analysis by NMR and/or X-ray crystallography. The sequence and solution structure of the tRNA-like domains were analysed by various methods including structural mapping with chemical and enzymatic probes and 2D NMR spectroscopy. The minimalist RNAs contain two post-transcriptional base modifications, 5-methyluridine and pseudouridine, as the full-length tmRNA. Both RNAs fold into three stems, a D-analogue, a T-loop and a GAAA tetra-loop. 2D NMR analysis of the imino proton resonances of both RNAs allowed the assignment of the three stems and of a number of tertiary interactions. It shows the existence of interactions between the TPsiC-loop and the D-analogue, exhibiting a number of similarities and also differences with the canonical tRNA fold, indicating that RNA tertiary interactions can be modulated according to the sequence and secondary structure contexts. Furthermore, the E.coli minimalist RNA is aminoacylatable with alanine with a catalytic efficiency an order of magnitude higher than that for full-length tmRNA.
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Affiliation(s)
- Cyril Gaudin
- Laboratoire de Biochimie Pharmaceutique UPRES JE2311, Faculté de Pharmacie, Université de Rennes I, 2 avenue du Pr. Léon Bernard, 35043, Rennes, France
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19
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Du X, Wang ED. Tertiary structure base pairs between D- and TpsiC-loops of Escherichia coli tRNA(Leu) play important roles in both aminoacylation and editing. Nucleic Acids Res 2003; 31:2865-72. [PMID: 12771213 PMCID: PMC156717 DOI: 10.1093/nar/gkg382] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To ensure the fidelity of protein biosynthesis, aminoacyl-tRNA synthetases (aaRSs) must recognize the tRNA identity elements of their cognate tRNAs and discriminate their cognate amino acids from structurally similar ones through a proofreading (editing) reaction. For a better understanding of these processes, we investigated the role of tRNA(Leu) tertiary structure in the aminoacylation and editing reactions catalyzed by leucyl-tRNA synthetase (LeuRS). We constructed a series of Escherichia coli tRNA(Leu) mutated transcripts with alterations of the nucleotides involved in tertiary interactions. Our results revealed that any disturbance of the tertiary interaction between the tRNA(Leu) D- and TpsiC-loops affected both its aminoacylation ability and its ability to stimulate the editing reaction. Moreover, we found that the various tertiary interactions between the D- and TpsiC-loops (G18:U55, G19:C56 and U54:A58) functioned differently within the aminoacylation and editing reactions. In these two reactions, the role of base pair 19:56 was closely correlated and dependent on the hydrogen bond number. In contrast, U54:A58 was more important in aminoacylation than in editing. Taken together, our results suggest that the elbow region of tRNA formed by the tertiary interactions between the D- and TpsiC-loops affects the interactions between tRNA and aaRS effectively both in aminoacylation and in editing.
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MESH Headings
- Acylation
- Adenosine Triphosphate/metabolism
- Base Pairing
- Base Sequence
- Escherichia coli/genetics
- Hydrogen Bonding
- Isoleucine/metabolism
- Leucine/metabolism
- Leucine-tRNA Ligase/metabolism
- Molecular Sequence Data
- Mutation
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer, Leu/chemistry
- RNA, Transfer, Leu/genetics
- RNA, Transfer, Leu/metabolism
- Transcription, Genetic
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Affiliation(s)
- Xing Du
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China
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de Smit MH, Gultyaev AP, Hilge M, Bink HHJ, Barends S, Kraal B, Pleij CWA. Structural variation and functional importance of a D-loop-T-loop interaction in valine-accepting tRNA-like structures of plant viral RNAs. Nucleic Acids Res 2002; 30:4232-40. [PMID: 12364602 PMCID: PMC140539 DOI: 10.1093/nar/gkf539] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Valine-accepting tRNA-like structures (TLSs) are found at the 3' ends of the genomic RNAs of most plant viruses belonging to the genera Tymovirus, Furovirus, Pomovirus and Pecluvirus, and of one Tobamovirus species. Sequence alignment of these TLSs suggests the existence of a tertiary D-loop-T-loop interaction consisting of 2 bp, analogous to those in the elbow region of canonical tRNAs. The conserved G(18).Psi(55) pair of regular tRNAs is found to covary in these TLSs between G.U (possibly also modified to G.Psi) and A.G. We have mutated the relevant bases in turnip yellow mosaic virus (TYMV) and examined the mutants for symptom development on Chinese cabbage plants and for accumulation of genetic reversions. Development of symptoms is shown to rely on the presence of either A.G or G.U in the original mutants or in revertants. This finding supports the existence and functional importance of this tertiary interaction. The fact that only G.U and A.G are accepted at this position appears to result from steric and energetic limitations related to the highly compact nature of the elbow region. We discuss the implications of these findings for the various possible functions of the valine-accepting TLS.
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Affiliation(s)
- Maarten H de Smit
- Group Genexpress, Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
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