1
|
Campos-Silva R, D’Urso G, Delalande O, Giudice E, Macedo AJ, Gillet R. Trans-Translation Is an Appealing Target for the Development of New Antimicrobial Compounds. Microorganisms 2021; 10:3. [PMID: 35056452 PMCID: PMC8778911 DOI: 10.3390/microorganisms10010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/09/2021] [Accepted: 12/16/2021] [Indexed: 01/06/2023] Open
Abstract
Because of the ever-increasing multidrug resistance in microorganisms, it is crucial that we find and develop new antibiotics, especially molecules with different targets and mechanisms of action than those of the antibiotics in use today. Translation is a fundamental process that uses a large portion of the cell's energy, and the ribosome is already the target of more than half of the antibiotics in clinical use. However, this process is highly regulated, and its quality control machinery is actively studied as a possible target for new inhibitors. In bacteria, ribosomal stalling is a frequent event that jeopardizes bacterial wellness, and the most severe form occurs when ribosomes stall at the 3'-end of mRNA molecules devoid of a stop codon. Trans-translation is the principal and most sophisticated quality control mechanism for solving this problem, which would otherwise result in inefficient or even toxic protein synthesis. It is based on the complex made by tmRNA and SmpB, and because trans-translation is absent in eukaryotes, but necessary for bacterial fitness or survival, it is an exciting and realistic target for new antibiotics. Here, we describe the current and future prospects for developing what we hope will be a novel generation of trans-translation inhibitors.
Collapse
Affiliation(s)
- Rodrigo Campos-Silva
- CNRS, Institut de Génétique et Développement de Rennes (IGDR) UMR6290, University of Rennes, 35000 Rennes, France; (R.C.-S.); (G.D.); (O.D.); (E.G.)
- Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia and Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre 90610-000, Brazil;
| | - Gaetano D’Urso
- CNRS, Institut de Génétique et Développement de Rennes (IGDR) UMR6290, University of Rennes, 35000 Rennes, France; (R.C.-S.); (G.D.); (O.D.); (E.G.)
| | - Olivier Delalande
- CNRS, Institut de Génétique et Développement de Rennes (IGDR) UMR6290, University of Rennes, 35000 Rennes, France; (R.C.-S.); (G.D.); (O.D.); (E.G.)
| | - Emmanuel Giudice
- CNRS, Institut de Génétique et Développement de Rennes (IGDR) UMR6290, University of Rennes, 35000 Rennes, France; (R.C.-S.); (G.D.); (O.D.); (E.G.)
| | - Alexandre José Macedo
- Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia and Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre 90610-000, Brazil;
| | - Reynald Gillet
- CNRS, Institut de Génétique et Développement de Rennes (IGDR) UMR6290, University of Rennes, 35000 Rennes, France; (R.C.-S.); (G.D.); (O.D.); (E.G.)
| |
Collapse
|
2
|
Fritze J, Zhang M, Luo Q, Lu X. An overview of the bacterial SsrA system modulating intracellular protein levels and activities. Appl Microbiol Biotechnol 2020; 104:5229-5241. [PMID: 32342145 DOI: 10.1007/s00253-020-10623-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/07/2020] [Accepted: 04/13/2020] [Indexed: 12/18/2022]
Abstract
In bacteria, the truncated forms of mRNAs, which usually lack a stop codon, are occasionally generated by premature termination of gene transcription and/or endo- or exonucleolytic cleavage events. Ribosomes proceeding on these molecules stall at the 3' end of the chain and are rescued by a widely distributed mechanism known as trans-translation, which includes two essential elements, ssrA RNA (a special RNA) and SmpB (a small protein). Through this mechanism, the polypeptides translated from truncated mRNAs are marked by a short peptide, known as SsrA tag, at their C-termini and directed to the specific endogenous proteases for C-terminal proteolysis. Based on the deep understanding of the SsrA tagging and degradation mechanisms, recently a series of SsrA-based genetic tools have been developed for gene regulation on the level of post-translation. They are successfully applied for controllable regulation of biological circuits in bacteria. In the present article, we systematically summarize the history, structural characteristics, and functional mechanisms of the SsrA tagging and degrading machineries, as well as their technical uses and limitations.Key Points• SsrA system plays an important role in ribosome rescue in bacteria.• SsrA-based genetic tools are useful for controlling protein levels and activities.
Collapse
Affiliation(s)
- Jacques Fritze
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,University of Stuttgart, Stuttgart, Germany
| | - Mingyi Zhang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Quan Luo
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China. .,School of Life Sciences, Hubei University, Wuhan, China.
| | - Xuefeng Lu
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China. .,Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China. .,Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China. .,Marine Biology and Biotechnology Laboratory, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
| |
Collapse
|
3
|
Mraheil MA, Frantz R, Teubner L, Wendt H, Linne U, Wingerath J, Wirth T, Chakraborty T. Requirement of the RNA-binding protein SmpB during intracellular growth of Listeria monocytogenes. Int J Med Microbiol 2017; 307:166-173. [PMID: 28202229 DOI: 10.1016/j.ijmm.2017.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/24/2017] [Accepted: 01/30/2017] [Indexed: 10/20/2022] Open
Abstract
Bacterial trans-translation is the main quality control mechanism employed to relieve stalled ribosomes. Trans-translation is mediated by the small protein B (SmpB) and transfer-mRNA (tmRNA) ribonucleoprotein complex, which interacts with translational complexes stalled at the 3' end of non-stop mRNAs to release the stalled ribosomes thereby targeting the nascent polypeptides and truncated mRNAs for degradation. The trans-translation system exists with a few exceptions in all bacteria. In the present study, we assessed the contribution of SmpB to the growth and virulence of Listeria monocytogenes, a human intracellular food-borne pathogen that colonizes host tissues to cause severe invasive infections. A smpB knockout significantly decreased the intracellular growth rate of L. monocytogenes during infection of murine macrophages. In addition, the mutant strain was attenuated for virulence when examined with the Galleria mellonella larvae killing assay and the organ colonisation model of mice following infection. Proteomic analysis of whole cell extracts of ΔsmpB deletion mutant revealed elevated protein levels of several proteins involved in ribosome assembly and interaction with tRNA substrates. These included the elongation factor Tu [EF-Tu] which promotes the GTP-dependent binding of aminoacyl-tRNA to the A-site of ribosomes during protein biosynthesis as well as the CysK which is known to interact with bacterial toxins that cleave tRNA substrates. The data presented here shed light on the role of SmpB and trans-translation during intracellular growth of L. monocytogenes.
Collapse
Affiliation(s)
- Mobarak Abu Mraheil
- Institute of Medical Microbiology, German Center for Infection Giessen-Marburg-Langen Site, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany.
| | - Renate Frantz
- Institute of Medical Microbiology, German Center for Infection Giessen-Marburg-Langen Site, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Lisa Teubner
- Institute of Medical Microbiology, German Center for Infection Giessen-Marburg-Langen Site, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Heiko Wendt
- Institute of Medical Microbiology, German Center for Infection Giessen-Marburg-Langen Site, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| | - Uwe Linne
- Department of Chemistry, and LOEWE-Center for Synthetic Microbiology Core Facility for Mass Spectrometry, Philipps-University Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Jessica Wingerath
- Department of Gastroenterology, Hepatology and Endocrinology, Medical School Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Thomas Wirth
- Department of Gastroenterology, Hepatology and Endocrinology, Medical School Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Trinad Chakraborty
- Institute of Medical Microbiology, German Center for Infection Giessen-Marburg-Langen Site, Justus Liebig University Giessen, Schubertstrasse 81, 35392 Giessen, Germany
| |
Collapse
|
4
|
Simms CL, Thomas EN, Zaher HS. Ribosome-based quality control of mRNA and nascent peptides. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27193249 DOI: 10.1002/wrna.1366] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 11/06/2022]
Abstract
Quality control processes are widespread and play essential roles in detecting defective molecules and removing them in order to maintain organismal fitness. Aberrant messenger RNA (mRNA) molecules, unless properly managed, pose a significant hurdle to cellular proteostasis. Often mRNAs harbor premature stop codons, possess structures that present a block to the translational machinery, or lack stop codons entirely. In eukaryotes, the three cytoplasmic mRNA-surveillance processes, nonsense-mediated decay (NMD), no-go decay (NGD), and nonstop decay (NSD), evolved to cope with these aberrant mRNAs, respectively. Nonstop mRNAs and mRNAs that inhibit translation elongation are especially problematic as they sequester valuable ribosomes from the translating ribosome pool. As a result, in addition to RNA degradation, NSD and NGD are intimately coupled to ribosome rescue in all domains of life. Furthermore, protein products produced from all three classes of defective mRNAs are more likely to malfunction. It is not surprising then that these truncated nascent protein products are subject to degradation. Over the past few years, many studies have begun to document a central role for the ribosome in initiating the RNA and protein quality control processes. The ribosome appears to be responsible for recognizing the target mRNAs as well as for recruiting the factors required to carry out the processes of ribosome rescue and nascent protein decay. WIREs RNA 2017, 8:e1366. doi: 10.1002/wrna.1366 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Carrie L Simms
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Erica N Thomas
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Hani S Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| |
Collapse
|
5
|
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Kurita D, Chadani Y, Muto A, Abo T, Himeno H. ArfA recognizes the lack of mRNA in the mRNA channel after RF2 binding for ribosome rescue. Nucleic Acids Res 2014; 42:13339-52. [PMID: 25355516 PMCID: PMC4245945 DOI: 10.1093/nar/gku1069] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although trans-translation mediated by tmRNA-SmpB has long been known as the sole system to relieve bacterial stalled ribosomes, ArfA has recently been identified as an alternative factor for ribosome rescue in Escherichia coli. This process requires hydrolysis of nascent peptidyl-tRNA by RF2, which usually acts as a stop codon-specific peptide release factor. It poses a fascinating question of how ArfA and RF2 recognize and rescue the stalled ribosome. Here, we mapped the location of ArfA in the stalled ribosome by directed hydroxyl radical probing. It revealed an ArfA-binding site around the neck region of the 30S subunit in which the N- and C-terminal regions of ArfA are close to the decoding center and the mRNA entry channel, respectively. ArfA and RF2 sequentially enter the ribosome stalled in either the middle or 3′ end of mRNA, whereas RF2 induces a productive conformational change of ArfA only when ribosome is stalled at the 3′ end of mRNA. On the basis of these results, we propose that ArfA functions as the sensor to recognize the target ribosome after RF2 binding.
Collapse
Affiliation(s)
- Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | - Yuhei Chadani
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Akira Muto
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | - Tatsuhiko Abo
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan Department of Biology, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Hyouta Himeno
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| |
Collapse
|
8
|
Starosta AL, Lassak J, Jung K, Wilson DN. The bacterial translation stress response. FEMS Microbiol Rev 2014; 38:1172-201. [PMID: 25135187 DOI: 10.1111/1574-6976.12083] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 07/18/2014] [Accepted: 08/07/2014] [Indexed: 11/30/2022] Open
Abstract
Throughout their life, bacteria need to sense and respond to environmental stress. Thus, such stress responses can require dramatic cellular reprogramming, both at the transcriptional as well as the translational level. This review focuses on the protein factors that interact with the bacterial translational apparatus to respond to and cope with different types of environmental stress. For example, the stringent factor RelA interacts with the ribosome to generate ppGpp under nutrient deprivation, whereas a variety of factors have been identified that bind to the ribosome under unfavorable growth conditions to shut-down (RelE, pY, RMF, HPF and EttA) or re-program (MazF, EF4 and BipA) translation. Additional factors have been identified that rescue ribosomes stalled due to stress-induced mRNA truncation (tmRNA, ArfA, ArfB), translation of unfavorable protein sequences (EF-P), heat shock-induced subunit dissociation (Hsp15), or antibiotic inhibition (TetM, FusB). Understanding the mechanism of how the bacterial cell responds to stress will not only provide fundamental insight into translation regulation, but will also be an important step to identifying new targets for the development of novel antimicrobial agents.
Collapse
Affiliation(s)
- Agata L Starosta
- Gene Center, Department for Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany; Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Munich, Germany
| | | | | | | |
Collapse
|
9
|
Venkataraman K, Zafar H, Karzai AW. Distinct tmRNA sequence elements facilitate RNase R engagement on rescued ribosomes for selective nonstop mRNA decay. Nucleic Acids Res 2014; 42:11192-202. [PMID: 25200086 PMCID: PMC4176180 DOI: 10.1093/nar/gku802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
trans-Translation, orchestrated by SmpB and tmRNA, is the principal eubacterial pathway for resolving stalled translation complexes. RNase R, the leading nonstop mRNA surveillance factor, is recruited to stalled ribosomes in a trans-translation dependent process. To elucidate the contributions of SmpB and tmRNA to RNase R recruitment, we evaluated Escherichia coli–Francisella tularensis chimeric variants of tmRNA and SmpB. This evaluation showed that while the hybrid tmRNA supported nascent polypeptide tagging and ribosome rescue, it suffered defects in facilitating RNase R recruitment to stalled ribosomes. To gain further insights, we used established tmRNA and SmpB variants that impact distinct stages of the trans-translation process. Analysis of select tmRNA variants revealed that the sequence composition and positioning of the ultimate and penultimate codons of the tmRNA ORF play a crucial role in recruiting RNase R to rescued ribosomes. Evaluation of defined SmpB C-terminal tail variants highlighted the importance of establishing the tmRNA reading frame, and provided valuable clues into the timing of RNase R recruitment to rescued ribosomes. Taken together, these studies demonstrate that productive RNase R-ribosomes engagement requires active trans-translation, and suggest that RNase R captures the emerging nonstop mRNA at an early stage after establishment of the tmRNA ORF as the surrogate mRNA template.
Collapse
Affiliation(s)
- Krithika Venkataraman
- Department of Biochemistry and Cell Biology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY 11794, USA
| | - Hina Zafar
- Department of Biochemistry and Cell Biology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY 11794, USA
| | - A Wali Karzai
- Department of Biochemistry and Cell Biology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY 11794, USA
| |
Collapse
|
10
|
Miller MR, Buskirk AR. The SmpB C-terminal tail helps tmRNA to recognize and enter stalled ribosomes. Front Microbiol 2014; 5:462. [PMID: 25228900 PMCID: PMC4151336 DOI: 10.3389/fmicb.2014.00462] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 08/14/2014] [Indexed: 11/13/2022] Open
Abstract
In bacteria, transfer-messenger RNA (tmRNA) and SmpB comprise the most common and effective system for rescuing stalled ribosomes. Ribosomes stall on mRNA transcripts lacking stop codons and are rescued as the defective mRNA is swapped for the tmRNA template in a process known as trans-translation. The tmRNA–SmpB complex is recruited to the ribosome independent of a codon–anticodon interaction. Given that the ribosome uses robust discriminatory mechanisms to select against non-cognate tRNAs during canonical decoding, it has been hard to explain how this can happen. Recent structural and biochemical studies show that SmpB licenses tmRNA entry through its interactions with the decoding center and mRNA channel. In particular, the C-terminal tail of SmpB promotes both EFTu activation and accommodation of tmRNA, the former through interactions with 16S rRNA nucleotide G530 and the latter through interactions with the mRNA channel downstream of the A site. Here we present a detailed model of the earliest steps in trans-translation, and in light of these mechanistic considerations, revisit the question of how tmRNA preferentially reacts with stalled, non-translating ribosomes.
Collapse
Affiliation(s)
- Mickey R Miller
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT USA
| | - Allen R Buskirk
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD USA
| |
Collapse
|
11
|
Himeno H, Kurita D, Muto A. tmRNA-mediated trans-translation as the major ribosome rescue system in a bacterial cell. Front Genet 2014; 5:66. [PMID: 24778639 PMCID: PMC3985003 DOI: 10.3389/fgene.2014.00066] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 03/15/2014] [Indexed: 11/13/2022] Open
Abstract
Transfer messenger RNA (tmRNA; also known as 10Sa RNA or SsrA RNA) is a small RNA molecule that is conserved among bacteria. It has structural and functional similarities to tRNA: it has an upper half of the tRNA-like structure, its 5’ end is processed by RNase P, it has typical tRNA-specific base modifications, it is aminoacylated with alanine, it binds to EF-Tu after aminoacylation and it enters the ribosome with EF-Tu and GTP. However, tmRNA lacks an anticodon, and instead it has a coding sequence for a short peptide called tag-peptide. An elaborate interplay of actions of tmRNA as both tRNA and mRNA with the help of a tmRNA-binding protein, SmpB, facilitates trans-translation, which produces a single polypeptide from two mRNA molecules. Initially alanyl-tmRNA in complex with EF-Tu and SmpB enters the vacant A-site of the stalled ribosome like aminoacyl-tRNA but without a codon–anticodon interaction, and subsequently truncated mRNA is replaced with the tag-encoding region of tmRNA. During these processes, not only tmRNA but also SmpB structurally and functionally mimics both tRNA and mRNA. Thus trans-translation rescues the stalled ribosome, thereby allowing recycling of the ribosome. Since the tag-peptide serves as a target of AAA+ proteases, the trans-translation products are preferentially degraded so that they do not accumulate in the cell. Although alternative rescue systems have recently been revealed, trans-translation is the only system that universally exists in bacteria. Furthermore, it is unique in that it employs a small RNA and that it prevents accumulation of non-functional proteins from truncated mRNA in the cell. It might play the major role in rescuing the stalled translation in the bacterial cell.
Collapse
Affiliation(s)
- Hyouta Himeno
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University Hirosaki, Japan
| | - Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University Hirosaki, Japan
| | - Akira Muto
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University Hirosaki, Japan
| |
Collapse
|
12
|
Abstract
Problems during gene expression can result in a ribosome that has translated to the 3' end of an mRNA without terminating at a stop codon, forming a nonstop translation complex. The nonstop translation complex contains a ribosome with the mRNA and peptidyl-tRNA engaged, but because there is no codon in the A site, the ribosome cannot elongate or terminate the nascent chain. Recent work has illuminated the importance of resolving these nonstop complexes in bacteria. Transfer-messenger RNA (tmRNA)-SmpB specifically recognizes and resolves nonstop translation complexes in a reaction known as trans-translation. trans-Translation releases the ribosome and promotes degradation of the incomplete nascent polypeptide and problematic mRNA. tmRNA and SmpB have been found in all bacteria and are essential in some species. However, other bacteria can live without trans-translation because they have one of the alternative release factors, ArfA or ArfB. ArfA recruits RF2 to nonstop translation complexes to promote hydrolysis of the peptidyl-tRNAs. ArfB recognizes nonstop translation complexes in a manner similar to tmRNA-SmpB recognition and directly hydrolyzes the peptidyl-tRNAs to release the stalled ribosomes. Genetic studies indicate that most or all species require at least one mechanism to resolve nonstop translation complexes. Consistent with such a requirement, small molecules that inhibit resolution of nonstop translation complexes have broad-spectrum antibacterial activity. These results suggest that resolving nonstop translation complexes is a matter of life or death for bacteria.
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Miller MR, Buskirk AR. An unusual mechanism for EF-Tu activation during tmRNA-mediated ribosome rescue. RNA (NEW YORK, N.Y.) 2014; 20:228-235. [PMID: 24345396 PMCID: PMC3895274 DOI: 10.1261/rna.042226.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 11/07/2013] [Indexed: 06/03/2023]
Abstract
In bacteria, ribosomes stalled on truncated mRNAs are rescued by transfer-messenger RNA (tmRNA) and its protein partner SmpB. Acting like tRNA, the aminoacyl-tmRNA/SmpB complex is delivered to the ribosomal A site by EF-Tu and accepts the transfer of the nascent polypeptide. Although SmpB binding within the decoding center is clearly critical for licensing tmRNA entry into the ribosome, it is not known how activation of EF-Tu occurs in the absence of a codon-anticodon interaction. A recent crystal structure revealed that SmpB residue His136 stacks on 16S rRNA nucleotide G530, a critical player in the canonical decoding mechanism. Here we use pre-steady-state kinetic methods to probe the role of this interaction in ribosome rescue. We find that although mutation of His136 does not reduce SmpB's affinity for the ribosomal A-site, it dramatically reduces the rate of GTP hydrolysis by EF-Tu. Surprisingly, the same mutation has little effect on the apparent rate of peptide-bond formation, suggesting that release of EF-Tu from the tmRNA/SmpB complex on the ribosome may occur prior to GTP hydrolysis. Consistent with this idea, we find that peptidyl transfer to tmRNA is relatively insensitive to the antibiotic kirromycin. Taken together, our studies provide a model for the initial stages of ribosomal rescue by tmRNA.
Collapse
|
16
|
Kogure H, Handa Y, Nagata M, Kanai N, Güntert P, Kubota K, Nameki N. Identification of residues required for stalled-ribosome rescue in the codon-independent release factor YaeJ. Nucleic Acids Res 2013; 42:3152-63. [PMID: 24322300 PMCID: PMC3950681 DOI: 10.1093/nar/gkt1280] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The YaeJ protein is a codon-independent release factor with peptidyl-tRNA hydrolysis (PTH) activity, and functions as a stalled-ribosome rescue factor in Escherichia coli. To identify residues required for YaeJ function, we performed mutational analysis for in vitro PTH activity towards rescue of ribosomes stalled on a non-stop mRNA, and for ribosome-binding efficiency. We focused on residues conserved among bacterial YaeJ proteins. Additionally, we determined the solution structure of the GGQ domain of YaeJ from E. coli using nuclear magnetic resonance spectroscopy. YaeJ and a human homolog, ICT1, had similar levels of PTH activity, despite various differences in sequence and structure. While no YaeJ-specific residues important for PTH activity occur in the structured GGQ domain, Arg118, Leu119, Lys122, Lys129 and Arg132 in the following C-terminal extension were required for PTH activity. All of these residues are completely conserved among bacteria. The equivalent residues were also found in the C-terminal extension of ICT1, allowing an appropriate sequence alignment between YaeJ and ICT1 proteins from various species. Single amino acid substitutions for each of these residues significantly decreased ribosome-binding efficiency. These biochemical findings provide clues to understanding how YaeJ enters the A-site of stalled ribosomes.
Collapse
Affiliation(s)
- Hiroyuki Kogure
- Division of Molecular Science, Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan, Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance, and Frankfurt Institute for Advanced Studies, Goethe University, Frankfurt am Main, Germany and Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan
| | | | | | | | | | | | | |
Collapse
|
17
|
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.
Collapse
Affiliation(s)
- Emmanuel Giudice
- Translation and Folding Team, Université de Rennes 1, UMR CNRS 6290 IGDR, Campus de Beaulieu 35042 Rennes cedex, France
| | | |
Collapse
|
18
|
Inada T. Quality control systems for aberrant mRNAs induced by aberrant translation elongation and termination. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:634-42. [PMID: 23416749 DOI: 10.1016/j.bbagrm.2013.02.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 10/27/2022]
Abstract
RNA processing is an essential gene expression step and plays a crucial role to achieve diversity of gene products in eukaryotes. Various aberrant mRNAs transiently produced during RNA processing reactions are recognized and eliminated by specific quality control systems. It has been demonstrated that these mRNA quality control systems stimulate the degradation of aberrant mRNA to prevent the potentially harmful products derived from aberrant mRNAs. Recent studies on quality control systems induced by abnormal translation elongation and termination have revealed that both aberrant mRNAs and proteins are subjected to rapid degradation. In NonStop Decay (NSD) quality control system, a poly(A) tail of nonstop mRNA is translated and the synthesis of poly-lysine sequence results in translation arrest followed by co-translational degradation of aberrant nonstop protein. In No-Go Decay (NGD) quality control system, the specific amino acid sequences of the nascent polypeptide induce ribosome stalling, and the arrest products are ubiquitinated and rapidly degraded by the proteasome. In Nonfunctional rRNA Decay (NRD) quality control system, aberrant ribosomes composed of nonfunctional ribosomal RNAs are also eliminated when aberrant translation elongation complexes are formed on mRNA. I describe recent progresses on the mechanisms of quality control systems and the relationships between quality control systems. This article is part of a Special issue entitled: RNA Decay mechanisms.
Collapse
|
19
|
Imataka H. Single-molecule imaging with a tagged ribosome to explore trans-translation. J Biochem 2012; 152:293-5. [PMID: 22923739 DOI: 10.1093/jb/mvs091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Single-molecule imaging is a powerful technique to visualize molecular interactions and movements. Translation is one of the most interesting targets for researchers with the molecular-imaging skills, since mRNA, tRNA and translation factors interact with or move inside or on the ribosome in an ordered manner. Trans-translation is a bacterial quality control system to rescue the ribosomes stalled at the 3' end of the mRNA, and this phenomenon is recapitulated in vitro with defined factors including two trans-translation-specific entities tmRNA and SmpB. Zhou et al. (Single molecule imaging of the trans-translation entry process via anchoring of the tagged ribosome. J Biochem 2011;149:609-618.) successfully visualized the interaction of the tmRNA-SmpB complex with the ribosome by immobilizing the ribosome on the quartz surface with the HaloTag technology. This ribosome-anchoring system may be useful for the imaging analysis of other processes of translation.
Collapse
Affiliation(s)
- Hiroaki Imataka
- Department of Materials Science and Chemistry, Molecular Nanotechnology Research Center, Graduate School of Engineering, University of Hyogo, Himeji 671-2280, Japan.
| |
Collapse
|
20
|
Gagnon MG, Seetharaman SV, Bulkley D, Steitz TA. Structural basis for the rescue of stalled ribosomes: structure of YaeJ bound to the ribosome. Science 2012; 335:1370-2. [PMID: 22422986 DOI: 10.1126/science.1217443] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In bacteria, the hybrid transfer-messenger RNA (tmRNA) rescues ribosomes stalled on defective messenger RNAs (mRNAs). However, certain gram-negative bacteria have evolved proteins that are capable of rescuing stalled ribosomes in a tmRNA-independent manner. Here, we report a 3.2 angstrom-resolution crystal structure of the rescue factor YaeJ bound to the Thermus thermophilus 70S ribosome in complex with the initiator tRNA(i)(fMet) and a short mRNA. The structure reveals that the C-terminal tail of YaeJ functions as a sensor to discriminate between stalled and actively translating ribosomes by binding in the mRNA entry channel downstream of the A site between the head and shoulder of the 30S subunit. This allows the N-terminal globular domain to sample different conformations, so that its conserved GGQ motif is optimally positioned to catalyze the hydrolysis of peptidyl-tRNA. This structure gives insights into the mechanism of YaeJ function and provides a basis for understanding how it rescues stalled ribosomes.
Collapse
Affiliation(s)
- Matthieu G Gagnon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | | | | | | |
Collapse
|
21
|
Neubauer C, Gillet R, Kelley AC, Ramakrishnan V. Decoding in the absence of a codon by tmRNA and SmpB in the ribosome. Science 2012; 335:1366-9. [PMID: 22422985 PMCID: PMC3763467 DOI: 10.1126/science.1217039] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In bacteria, ribosomes stalled at the end of truncated messages are rescued by transfer-messenger RNA (tmRNA), a bifunctional molecule that acts as both a transfer RNA (tRNA) and a messenger RNA (mRNA), and SmpB, a small protein that works in concert with tmRNA. Here, we present the crystal structure of a tmRNA fragment, SmpB and elongation factor Tu bound to the ribosome at 3.2 angstroms resolution. The structure shows how SmpB plays the role of both the anticodon loop of tRNA and portions of mRNA to facilitate decoding in the absence of an mRNA codon in the A site of the ribosome and explains why the tmRNA-SmpB system does not interfere with normal translation.
Collapse
MESH Headings
- Anticodon
- Bacterial Proteins/chemistry
- Bacterial Proteins/metabolism
- Base Sequence
- Crystallography, X-Ray
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Peptide Elongation Factor Tu/chemistry
- Peptide Elongation Factor Tu/metabolism
- Protein Biosynthesis
- Protein Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/metabolism
- Ribosome Subunits, Small, Bacterial/chemistry
- Ribosome Subunits, Small, Bacterial/metabolism
- Ribosome Subunits, Small, Bacterial/ultrastructure
- Ribosomes/chemistry
- Ribosomes/metabolism
- Ribosomes/ultrastructure
- Thermus thermophilus/chemistry
- Thermus thermophilus/genetics
- Thermus thermophilus/metabolism
- Thermus thermophilus/ultrastructure
Collapse
Affiliation(s)
- Cajetan Neubauer
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
| | - Reynald Gillet
- Université de Rennes 1 and Institut Universitaire de France, “Translation and Folding” group, UMR CNRS 6290, IGDR, Campus de Beaulieu 35042 Rennes cedex, France
| | - Ann C. Kelley
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
| | - V. Ramakrishnan
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
| |
Collapse
|
22
|
Miller MR, Liu Z, Cazier DJ, Gebhard GM, Herron SR, Zaher HS, Green R, Buskirk AR. The role of SmpB and the ribosomal decoding center in licensing tmRNA entry into stalled ribosomes. RNA (NEW YORK, N.Y.) 2011; 17:1727-1736. [PMID: 21795410 PMCID: PMC3162337 DOI: 10.1261/rna.2821711] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 06/24/2011] [Indexed: 05/31/2023]
Abstract
In bacteria, stalled ribosomes are recycled by a hybrid transfer-messenger RNA (tmRNA). Like tRNA, tmRNA is aminoacylated with alanine and is delivered to the ribosome by EF-Tu, where it reacts with the growing polypeptide chain. tmRNA entry into stalled ribosomes poses a challenge to our understanding of ribosome function because it occurs in the absence of a codon-anticodon interaction. Instead, tmRNA entry is licensed by the binding of its protein partner, SmpB, to the ribosomal decoding center. We analyzed a series of SmpB mutants and found that its C-terminal tail is essential for tmRNA accommodation but not for EF-Tu activation. We obtained evidence that the tail likely functions as a helix on the ribosome to promote accommodation and identified key residues in the tail essential for this step. In addition, our mutational analysis points to a role for the conserved K(131)GKK tail residues in trans-translation after peptidyl transfer to tmRNA, presumably EF-G-mediated translocation or translation of the tmRNA template. Surprisingly, analysis of A1492, A1493, and G530 mutants reveals that while these ribosomal nucleotides are essential for normal tRNA selection, they play little to no role in peptidyl transfer to tmRNA. These studies clarify how SmpB interacts with the ribosomal decoding center to license tmRNA entry into stalled ribosomes.
Collapse
Affiliation(s)
- Mickey R. Miller
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - Zhu Liu
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - DeAnna J. Cazier
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - Grant M. Gebhard
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - Steven R. Herron
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| | - Hani S. Zaher
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Rachel Green
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Allen R. Buskirk
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
| |
Collapse
|
23
|
Keiler KC, Ramadoss NS. Bifunctional transfer-messenger RNA. Biochimie 2011; 93:1993-7. [PMID: 21664408 DOI: 10.1016/j.biochi.2011.05.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 05/25/2011] [Indexed: 01/14/2023]
Abstract
Transfer-messenger RNA (tmRNA) is a bifunctional RNA that has properties of a tRNA and an mRNA. tmRNA uses these two functions to release ribosomes stalled during translation and target the nascent polypeptides for degradation. This concerted reaction, known as trans-translation, contributes to translational quality control and regulation of gene expression in bacteria. tmRNA is conserved throughout bacteria, and is one of the most abundant RNAs in the cell, suggesting that trans-translation is of fundamental importance for bacterial fitness. Mutants lacking tmRNA activity typically have severe phenotypes, including defects in viability, virulence, and responses to environmental stresses.
Collapse
Affiliation(s)
- Kenneth C Keiler
- Pennsylvania State University, Department of Biochemistry & Molecular Biology, 401 Althouse Lab, University Park, PA 16802, USA.
| | | |
Collapse
|
24
|
Chadani Y, Ono K, Kutsukake K, Abo T. Escherichia coli YaeJ protein mediates a novel ribosome-rescue pathway distinct from SsrA- and ArfA-mediated pathways. Mol Microbiol 2011; 80:772-85. [DOI: 10.1111/j.1365-2958.2011.07607.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
25
|
Kurita D, Muto A, Himeno H. tRNA/mRNA Mimicry by tmRNA and SmpB in Trans-Translation. J Nucleic Acids 2011; 2011:130581. [PMID: 21253384 PMCID: PMC3022190 DOI: 10.4061/2011/130581] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 12/15/2010] [Indexed: 11/20/2022] Open
Abstract
Since accurate translation from mRNA to protein is critical to survival, cells have developed translational quality control systems. Bacterial ribosomes stalled on truncated mRNA are rescued by a system involving tmRNA and SmpB referred to as trans-translation. Here, we review current understanding of the mechanism of trans-translation. Based on results obtained by using directed hydroxyl radical probing, we propose a new type of molecular mimicry during trans-translation. Besides such chemical approaches, biochemical and cryo-EM studies have revealed the structural and functional aspects of multiple stages of trans-translation. These intensive works provide a basis for studying the dynamics of tmRNA/SmpB in the ribosome.
Collapse
Affiliation(s)
- Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | | | | |
Collapse
|
26
|
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.
Collapse
Affiliation(s)
- Félix Weis
- Université de Rennes, UMR CNRS Equipe Structure et Dynamique des Macromolécules, Rennes, France
| | | | | | | | | | | | | |
Collapse
|
27
|
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.
Collapse
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
Collapse
Affiliation(s)
- Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | | | | |
Collapse
|
28
|
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.
Collapse
Affiliation(s)
- Felix Weis
- Universite de Rennes 1, INSERM U835, Laboratoire de Biochimie Pharmaceutique, 35043 Rennes Cedex, France
| | | | | | | | | | | |
Collapse
|
29
|
Beyond ribosome rescue: tmRNA and co-translational processes. FEBS Lett 2009; 584:413-9. [PMID: 19914241 DOI: 10.1016/j.febslet.2009.11.023] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 11/09/2009] [Accepted: 11/09/2009] [Indexed: 11/23/2022]
Abstract
tmRNA is a unique bi-functional RNA that acts as both a tRNA and an mRNA to enter stalled ribosomes and direct the addition of a peptide tag to the C terminus of nascent polypeptides. Despite a reasonably clear understanding of tmRNA activity, the reason for its absolute conservation throughout the eubacteria is unknown. Although tmRNA plays many physiological roles in different bacterial systems, recent studies suggest a general role for trans-translation in monitoring protein folding and perhaps other co-translational processes. This review will focus on these new hypotheses and the data that support them.
Collapse
|
30
|
Holberger LE, Hayes CS. Ribosomal protein S12 and aminoglycoside antibiotics modulate A-site mRNA cleavage and transfer-messenger RNA activity in Escherichia coli. J Biol Chem 2009; 284:32188-200. [PMID: 19776006 DOI: 10.1074/jbc.m109.062745] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Translational pausing in Escherichia coli can lead to mRNA cleavage within the ribosomal A-site. A-site mRNA cleavage is thought to facilitate transfer-messenger RNA (tmRNA).SmpB- mediated recycling of stalled ribosome complexes. Here, we demonstrate that the aminoglycosides paromomycin and streptomycin inhibit A-site cleavage of stop codons during inefficient translation termination. Aminoglycosides also induced stop codon read-through, suggesting that these antibiotics alleviate ribosome pausing during termination. Streptomycin did not inhibit A-site cleavage in rpsL mutants, which express streptomycin-resistant variants of ribosomal protein S12. However, rpsL strains exhibited reduced A-site mRNA cleavage compared with rpsL(+) cells. Additionally, tmRNA.SmpB-mediated SsrA peptide tagging was significantly reduced in several rpsL strains but could be fully restored in a subset of mutants when treated with streptomycin. The streptomycin-dependent rpsL(P90K) mutant also showed significantly lower levels of A-site cleavage and tmRNA.SmpB activity. Mutations in rpsD (encoding ribosomal protein S4), which suppressed streptomycin dependence, were able to partially restore A-site cleavage to rpsL(P90K) cells but failed to increase tmRNA.SmpB activity. Taken together, these results show that perturbations to A-site structure and function modulate A-site mRNA cleavage and tmRNA.SmpB activity. We propose that tmRNA.SmpB binds to streptomycin-resistant rpsL ribosomes less efficiently, leading to a partial loss of ribosome rescue function in these mutants.
Collapse
Affiliation(s)
- Laura E Holberger
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106-9610, USA
| | | |
Collapse
|
31
|
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.
Collapse
Affiliation(s)
- Talina Watts
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | | | | | | |
Collapse
|
32
|
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.
Collapse
|
33
|
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.
Collapse
Affiliation(s)
- Kenneth C Keiler
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
| |
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- Mickey R Miller
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
| | | | | | | | | |
Collapse
|
35
|
Kimura T, Takagi K, Hirata Y, Hase Y, Muto A, Himeno H. Ribosome-small-subunit-dependent GTPase interacts with tRNA-binding sites on the ribosome. J Mol Biol 2008; 381:467-77. [PMID: 18588897 DOI: 10.1016/j.jmb.2008.06.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 06/03/2008] [Accepted: 06/07/2008] [Indexed: 10/21/2022]
Abstract
RsgA (ribosome-small-subunit-dependent GTPase A, also known as YjeQ) is a unique GTPase in that guanosine triphosphate hydrolytic activity is activated by the small subunit of the ribosome. Disruption of the gene for RsgA from the genome affects the growth of cells, the subunit association of the ribosome, and the maturation of 16S rRNA. To study the interaction of Escherichia coli RsgA with the ribosome, chemical modifications using dimethylsulfate and kethoxal were performed on the small subunit in the presence or in the absence of RsgA. The chemical reactivities at G530, A790, G925, G926, G966, C1054, G1339, G1405, A1413, and A1493 in 16S rRNA were reduced, while those at A532, A923, G1392, A1408, A1468, and A1483 were enhanced, by the addition of RsgA, together with 5'-guanylylimidodiphosphate. Among them, the chemical reactivities at A532, A790, A923, G925, G926, C1054, G1392, A1413, A1468, A1483, and A1493 were not changed when RsgA was added together with GDP. These results indicate that the binding of RsgA induces conformational changes around the A site, P site, and helix 44, and that guanosine triphosphate hydrolysis induces partial conformational restoration, especially in the head, to dissociate RsgA from the small subunit. RsgA has the capacity to coexist with mRNA in the ribosome while it promotes dissociation of tRNA from the ribosome.
Collapse
Affiliation(s)
- Takatsugu Kimura
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori 036-8561, Japan
| | | | | | | | | | | |
Collapse
|
36
|
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.
Collapse
Affiliation(s)
- Elizaveta Y Bugaeva
- Belozersky Institute, Build. A, Moscow State University, Moscow 119992, Russia
| | | | | | | | | |
Collapse
|