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Loh E, Lavender H, Tan F, Tracy A, Tang CM. Thermoregulation of Meningococcal fHbp, an Important Virulence Factor and Vaccine Antigen, Is Mediated by Anti-ribosomal Binding Site Sequences in the Open Reading Frame. PLoS Pathog 2016; 12:e1005794. [PMID: 27560142 PMCID: PMC4999090 DOI: 10.1371/journal.ppat.1005794] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 07/07/2016] [Indexed: 12/13/2022] Open
Abstract
During colonisation of the upper respiratory tract, bacteria are exposed to gradients of temperatures. Neisseria meningitidis is often present in the nasopharynx of healthy individuals, yet can occasionally cause severe disseminated disease. The meningococcus can evade the human complement system using a range of strategies that include recruitment of the negative complement regulator, factor H (CFH) via factor H binding protein (fHbp). We have shown previously that fHbp levels are influenced by the ambient temperature, with more fHbp produced at higher temperatures (i.e. at 37°C compared with 30°C). Here we further characterise the mechanisms underlying thermoregulation of fHbp, which occurs gradually over a physiologically relevant range of temperatures. We show that fHbp thermoregulation is not dependent on the promoters governing transcription of the bi- or mono-cistronic fHbp mRNA, or on meningococcal specific transcription factors. Instead, fHbp thermoregulation requires sequences located in the translated region of the mono-cistronic fHbp mRNA. Site-directed mutagenesis demonstrated that two anti-ribosomal binding sequences within the coding region of the fHbp transcript are involved in fHbp thermoregulation. Our results shed further light on mechanisms underlying the control of the production of this important virulence factor and vaccine antigen. The bacterium Neisseria meningitidis is exquisitely adapted to survive in the human host, and possesses several mechanisms to interact with host cells in the upper airway and to circumvent immune responses. However, the mechanisms that govern the expression of factors that contribute to colonisation and disease are incompletely understood. In this work, we further characterise how temperature influences the production of factor H binding protein (fHbp) by the meningococcus; fHbp recruits human complement proteins to the surface of the bacterium, and is an important vaccine antigen. We show that thermoregulation of fHbp occurs gradually over a physiological range of temperatures found in the upper airway, the site of colonisation. This regulation does not require specific meningococcal transcription factors, and sequence analysis indicates that fHbp mRNA forms a secondary structure which could act as an RNA thermosensor. Additional studies demonstrate that there are two specific sequences within the coding region of fHbp mRNA are important for thermosensing and could base-pair to the ribosome binding site, thus blocking translation of this protein. As fHbp is thermoregulated, vaccines that target this antigen might not impose a high level of selective pressure on the bacterium at the mucosal surface, thereby limiting herd immunity induce by fHbp containing vaccines.
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Affiliation(s)
- Edmund Loh
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Hayley Lavender
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Felicia Tan
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Alexander Tracy
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Christoph M. Tang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail:
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52
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Abstract
Pathogenic bacteria must withstand diverse host environments during infection. Environmental signals, such as pH, temperature, nutrient limitation, etc., not only trigger adaptive responses within bacteria to these specific stress conditions but also direct the expression of virulence genes at an appropriate time and place. An appreciation of stress responses and their regulation is therefore essential for an understanding of bacterial pathogenesis. This review considers specific stresses in the host environment and their relevance to pathogenesis, with a particular focus on the enteric pathogen Salmonella.
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Affiliation(s)
- Ferric C Fang
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195-7735, USA; Department of Laboratory Medicine, University of Washington School of Medicine, Seattle, WA 98195-7735, USA.
| | - Elaine R Frawley
- Department of Laboratory Medicine, University of Washington School of Medicine, Seattle, WA 98195-7735, USA
| | - Timothy Tapscott
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Andrés Vázquez-Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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53
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Garcia-Martin JA, Dotu I, Fernandez-Chamorro J, Lozano G, Ramajo J, Martinez-Salas E, Clote P. RNAiFold2T: Constraint Programming design of thermo-IRES switches. Bioinformatics 2016; 32:i360-i368. [PMID: 27307638 PMCID: PMC4908349 DOI: 10.1093/bioinformatics/btw265] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
MOTIVATION RNA thermometers (RNATs) are cis-regulatory elements that change secondary structure upon temperature shift. Often involved in the regulation of heat shock, cold shock and virulence genes, RNATs constitute an interesting potential resource in synthetic biology, where engineered RNATs could prove to be useful tools in biosensors and conditional gene regulation. RESULTS Solving the 2-temperature inverse folding problem is critical for RNAT engineering. Here we introduce RNAiFold2T, the first Constraint Programming (CP) and Large Neighborhood Search (LNS) algorithms to solve this problem. Benchmarking tests of RNAiFold2T against existent programs (adaptive walk and genetic algorithm) inverse folding show that our software generates two orders of magnitude more solutions, thus allowing ample exploration of the space of solutions. Subsequently, solutions can be prioritized by computing various measures, including probability of target structure in the ensemble, melting temperature, etc. Using this strategy, we rationally designed two thermosensor internal ribosome entry site (thermo-IRES) elements, whose normalized cap-independent translation efficiency is approximately 50% greater at 42 °C than 30 °C, when tested in reticulocyte lysates. Translation efficiency is lower than that of the wild-type IRES element, which on the other hand is fully resistant to temperature shift-up. This appears to be the first purely computational design of functional RNA thermoswitches, and certainly the first purely computational design of functional thermo-IRES elements. AVAILABILITY RNAiFold2T is publicly available as part of the new release RNAiFold3.0 at https://github.com/clotelab/RNAiFold and http://bioinformatics.bc.edu/clotelab/RNAiFold, which latter has a web server as well. The software is written in C ++ and uses OR-Tools CP search engine. CONTACT clote@bc.edu SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
| | - Ivan Dotu
- Department of Experimental and Health Sciences, Research Programme on Biomedical Informatics (GRIB), Universitat Pompeu Fabra. Dr. Aiguader 88, Barcelona, Spain
| | - Javier Fernandez-Chamorro
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Gloria Lozano
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Jorge Ramajo
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Encarnacion Martinez-Salas
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Peter Clote
- Biology Department, Boston College, Chestnut Hill, MA 02467, USA
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54
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Roßmanith J, Narberhaus F. Exploring the modular nature of riboswitches and RNA thermometers. Nucleic Acids Res 2016; 44:5410-23. [PMID: 27060146 PMCID: PMC4914106 DOI: 10.1093/nar/gkw232] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/28/2016] [Indexed: 01/20/2023] Open
Abstract
Natural regulatory RNAs like riboswitches and RNA thermometers (RNAT) have considerable potential in synthetic biology. They are located in the 5′ untranslated region (UTR) of bacterial mRNAs and sense small molecules or changes in temperature, respectively. While riboswitches act on the level of transcription, translation or mRNA stability, all currently known RNATs regulate translation initiation. In this study, we explored the modularity of riboswitches and RNATs and obtained regulatory devices with novel functionalities. In a first approach, we established three riboswitch-RNAT systems conferring dual regulation of transcription and translation depending on the two triggers ligand binding and temperature sensing. These consecutive fusions control gene expression in vivo and can even orchestrate complex cellular behavior. In another approach, we designed two temperature-controlled riboswitches by the integration of an RNAT into a riboswitch aptamer domain. These ‘thermoswitches’ respond to the cognate ligand at low temperatures and are turned into a continuous on-state by a temperature upshift. They represent the first RNATs taking control of transcription. Overall, this study demonstrates that riboswitches and RNATs are ideal for engineering synthetic RNA regulators due to their modular behavior.
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Affiliation(s)
| | - Franz Narberhaus
- Microbial Biology, Ruhr University Bochum, 44780 Bochum, Germany
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55
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Gao M, Gnutt D, Orban A, Appel B, Righetti F, Winter R, Narberhaus F, Müller S, Ebbinghaus S. Faltung einer RNA-Haarnadel in der dicht gedrängten Zelle. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510847] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mimi Gao
- Lehrstuhl für Physikalische Chemie II; Ruhr-Universität Bochum; Universitätsstr. 150 44801 Bochum Deutschland
| | - David Gnutt
- Lehrstuhl für Physikalische Chemie II; Ruhr-Universität Bochum; Universitätsstr. 150 44801 Bochum Deutschland
| | - Axel Orban
- Institut für Biochemie; Ernst-Moritz-Arndt-Universität Greifswald; Felix-Hausdorff-Str. 4 17487 Greifswald Deutschland
| | - Bettina Appel
- Institut für Biochemie; Ernst-Moritz-Arndt-Universität Greifswald; Felix-Hausdorff-Str. 4 17487 Greifswald Deutschland
| | - Francesco Righetti
- Biologie der Mikroorganismen; Ruhr-Universität Bochum; Universitätsstr. 150 44801 Bochum Deutschland
| | - Roland Winter
- Lehrstuhl für Physikalische Chemie I; TU Dortmund; Otto-Hahn-Str. 4a 44227 Dortmund Deutschland
| | - Franz Narberhaus
- Biologie der Mikroorganismen; Ruhr-Universität Bochum; Universitätsstr. 150 44801 Bochum Deutschland
| | - Sabine Müller
- Institut für Biochemie; Ernst-Moritz-Arndt-Universität Greifswald; Felix-Hausdorff-Str. 4 17487 Greifswald Deutschland
| | - Simon Ebbinghaus
- Lehrstuhl für Physikalische Chemie II; Ruhr-Universität Bochum; Universitätsstr. 150 44801 Bochum Deutschland
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56
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Gao M, Gnutt D, Orban A, Appel B, Righetti F, Winter R, Narberhaus F, Müller S, Ebbinghaus S. RNA Hairpin Folding in the Crowded Cell. Angew Chem Int Ed Engl 2016; 55:3224-8. [PMID: 26833452 PMCID: PMC4762321 DOI: 10.1002/anie.201510847] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 12/02/2022]
Abstract
Precise secondary and tertiary structure formation is critically important for the cellular functionality of ribonucleic acids (RNAs). RNA folding studies were mainly conducted in vitro, without the possibility of validating these experiments inside cells. Here, we directly resolve the folding stability of a hairpin‐structured RNA inside live mammalian cells. We find that the stability inside the cell is comparable to that in dilute physiological buffer. On the contrary, the addition of in vitro artificial crowding agents, with the exception of high‐molecular‐weight PEG, leads to a destabilization of the hairpin structure through surface interactions and reduction in water activity. We further show that RNA stability is highly variable within cell populations as well as within subcellular regions of the cytosol and nucleus. We conclude that inside cells the RNA is subject to (localized) stabilizing and destabilizing effects that lead to an on average only marginal modulation compared to diluted buffer.
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Affiliation(s)
- Mimi Gao
- Physical Chemistry II, Ruhr-Universität Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - David Gnutt
- Physical Chemistry II, Ruhr-Universität Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Axel Orban
- Institute for Biochemistry, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Bettina Appel
- Institute for Biochemistry, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Francesco Righetti
- Microbial Biology, Ruhr-Universität Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Roland Winter
- Physical Chemistry I, Technical University Dortmund, Otto-Hahn-Str. 4a, 44227, Dortmund, Germany
| | - Franz Narberhaus
- Microbial Biology, Ruhr-Universität Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Sabine Müller
- Institute for Biochemistry, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Simon Ebbinghaus
- Physical Chemistry II, Ruhr-Universität Bochum, Universitätsstr. 150, 44801, Bochum, Germany.
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57
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Karakostis K, Ponnuswamy A, Fusée LTS, Bailly X, Laguerre L, Worall E, Vojtesek B, Nylander K, Fåhraeus R. p53 mRNA and p53 Protein Structures Have Evolved Independently to Interact with MDM2. Mol Biol Evol 2016; 33:1280-92. [PMID: 26823446 DOI: 10.1093/molbev/msw012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The p53 tumor suppressor and its key regulator MDM2 play essential roles in development, ageing, cancer, and cellular stress responses in mammals. Following DNA damage, MDM2 interacts with p53 mRNA in an ATM kinase-dependent fashion and stimulates p53 synthesis, whereas under normal conditions, MDM2 targets the p53 protein for degradation. The peptide- and RNA motifs that interact with MDM2 are encoded by the same conserved BOX-I sequence, but how these interactions have evolved is unknown. Here, we show that a temperature-sensitive structure in the invertebrate Ciona intestinalis (Ci) p53 mRNA controls its interaction with MDM2. We also show that a nonconserved flanking region of Ci-BOX-I domain prevents the p53-MDM2 protein-protein interaction. These results indicate that the temperature-regulated p53 mRNA-MDM2 interaction evolved to become kinase regulated in the mammalian DNA damage response. The data also suggest that the negative regulation of p53 by MDM2 via protein-protein interaction evolved in vertebrates following changes in the BOX-I flanking sequence.
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Affiliation(s)
- Konstantinos Karakostis
- Équipe Labellisée Ligue Contre le Cancer, Université Paris 7, INSERM UMR 1162, Paris, France
| | - Anand Ponnuswamy
- Équipe Labellisée Ligue Contre le Cancer, Université Paris 7, INSERM UMR 1162, Paris, France
| | - Leïla T S Fusée
- Équipe Labellisée Ligue Contre le Cancer, Université Paris 7, INSERM UMR 1162, Paris, France
| | - Xavier Bailly
- UPMC-CNRS, FR2424, Station Biologique de Roscoff, Roscoff, France
| | - Laurent Laguerre
- UPMC-CNRS, FR2424, Station Biologique de Roscoff, Roscoff, France
| | - Erin Worall
- Edinburgh Cancer Research UK Centre, the University of Edinburgh, Edinburgh, United Kingdom
| | - Borek Vojtesek
- Regional Centre for Applied Molecular Oncology, RECAMO and Masaryk Memorial Cancer Institute, Brno, Czech Republic
| | - Karin Nylander
- Department of Medical Biosciences, Umeå University, Umeå, Sweden
| | - Robin Fåhraeus
- Équipe Labellisée Ligue Contre le Cancer, Université Paris 7, INSERM UMR 1162, Paris, France Regional Centre for Applied Molecular Oncology, RECAMO and Masaryk Memorial Cancer Institute, Brno, Czech Republic Department of Medical Biosciences, Umeå University, Umeå, Sweden
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58
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Abstract
Many Gram-negative pathogens express a type III secretion (T3SS) system to enable growth and survival within a host. The three human-pathogenic Yersinia species, Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica, encode the Ysc T3SS, whose expression is controlled by an AraC-like master regulator called LcrF. In this review, we discuss LcrF structure and function as well as the environmental cues and pathways known to regulate LcrF expression. Similarities and differences in binding motifs and modes of action between LcrF and the Pseudomonas aeruginosa homolog ExsA are summarized. In addition, we present a new bioinformatics analysis that identifies putative LcrF binding sites within Yersinia target gene promoters.
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59
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Stazic D, Voß B. The complexity of bacterial transcriptomes. J Biotechnol 2015; 232:69-78. [PMID: 26450562 DOI: 10.1016/j.jbiotec.2015.09.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 09/07/2015] [Accepted: 09/29/2015] [Indexed: 01/09/2023]
Abstract
For eukaryotes there seems to be no doubt that differences on the trancriptomic level substantially contribute to the process of species diversification, whereas for bacteria this is thought to be less important. Recent years saw a significant increase in full transcriptome studies for bacteria, which provided deep insight into the architecture of bacterial transcriptomes. Most notably, it became evident that, in contrast to previous scientific consensus, bacterial transcriptomes are quite complex. There exist a large number of cis-antisense RNAs, non-coding RNAs, overlapping transcripts and RNA elements that regulate transcription, such as riboswitches. Furthermore, processing and degradation of RNA has gained interest, because it has a significant impact on the composition of the transcriptome. In this review, we summarize recent findings and put them into a broader context with respect to the complexity of bacterial transcriptomes and its putative biological meanings.
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Affiliation(s)
- D Stazic
- University of Freiburg, Faculty of Biology, Computational Transcriptomics, Schänzlestr. 1, 79104 Freiburg, Germany.
| | - B Voß
- University of Freiburg, Faculty of Biology, Computational Transcriptomics, Schänzlestr. 1, 79104 Freiburg, Germany.
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60
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Abstract
Pathogenic bacteria sense environmental cues, including the local temperature, to control the production of key virulence factors. Thermal regulation can be achieved at the level of DNA, RNA or protein and although many virulence factors are subject to thermal regulation, the exact mechanisms of control are yet to be elucidated in many instances. Understanding how virulence factors are regulated by temperature presents a significant challenge, as gene expression and protein production are often influenced by complex regulatory networks involving multiple transcription factors in bacteria. Here we highlight some recent insights into thermal regulation of virulence in pathogenic bacteria. We focus on bacteria which cause disease in mammalian hosts, which are at a significantly higher temperature than the outside environment. We outline the mechanisms of thermal regulation and how understanding this fundamental aspect of the biology of bacteria has implications for pathogenesis and human health.
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Affiliation(s)
- Oliver Lam
- a The Sir William Dunn School of Pathology ; University of Oxford ; Oxford , UK
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61
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Audas TE, Lee S. Stressing out over long noncoding RNA. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1859:184-91. [PMID: 26142536 DOI: 10.1016/j.bbagrm.2015.06.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/17/2015] [Accepted: 06/19/2015] [Indexed: 12/26/2022]
Abstract
Genomic studies have revealed that humans possess far fewer protein-encoding genes than originally predicted. These over-estimates were drawn from the inherent developmental and stimuli-responsive complexity found in humans and other mammals, when compared to lower eukaryotic organisms. This left a conceptual void in many cellular networks, as a new class of functional molecules was necessary for "fine-tuning" the basic proteomic machinery. Transcriptomics analyses have determined that the vast majority of the genetic material is transcribed as noncoding RNA, suggesting that these molecules could provide the functional diversity initially sought from proteins. Indeed, as discussed in this review, long noncoding RNAs (lncRNAs), the largest family of noncoding transcripts, have emerged as common regulators of many cellular stressors; including heat shock, metabolic deprivation and DNA damage. These stimuli, while divergent in nature, share some common stress-responsive pathways, notably inhibition of cell proliferation. This role intrinsically makes stress-responsive lncRNA regulators potential tumor suppressor or proto-oncogenic genes. As the list of functional RNA molecules continues to rapidly expand it is becoming increasingly clear that the significance and functionality of this family may someday rival that of proteins. This article is part of a Special Issue entitled: Clues to long noncoding RNA taxonomy1, edited by Dr. Tetsuro Hirose and Dr. Shinichi Nakagawa.
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Affiliation(s)
- Timothy E Audas
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Stephen Lee
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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62
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Wang C, Jin C, Zhang J, Bao Q, Liu B, Tan H. Transcriptomic analysis of Thermoanaerobacter tengcongensis grown at different temperatures by RNA sequencing. J Genet Genomics 2015; 42:335-8. [PMID: 26165500 DOI: 10.1016/j.jgg.2015.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/26/2015] [Accepted: 03/03/2015] [Indexed: 10/23/2022]
Affiliation(s)
- Chuan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chunlei Jin
- School of Life Science, Wenzhou Medical University, Wenzhou 325035, China
| | - Jihui Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiyu Bao
- School of Life Science, Wenzhou Medical University, Wenzhou 325035, China
| | - Bo Liu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
| | - Huarong Tan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
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63
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Grosso-Becera MV, Servín-González L, Soberón-Chávez G. RNA structures are involved in the thermoregulation of bacterial virulence-associated traits. Trends Microbiol 2015; 23:509-18. [PMID: 25999019 DOI: 10.1016/j.tim.2015.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/01/2015] [Accepted: 04/16/2015] [Indexed: 11/25/2022]
Abstract
Pathogenic bacteria are exposed to temperature changes during colonization of the human body and during exposure to environmental conditions. Virulence-associated traits are mainly expressed by pathogenic bacteria at 37°C. We review different cases of post-transcriptional regulation of virulence-associated proteins through RNA structures (called RNA thermometers or RNATs) that modulate the translation of mRNAs. The analysis of RNATs in pathogenic bacteria has started to produce a comprehensive picture of the structures involved, and of the genes regulated by this mechanism. However, we are still not able to predict the functionality of putative RNATs predicted by bioinformatics methods, and there is not a global approach to measure the effect of these RNA structures in gene regulation during bacterial infections.
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Affiliation(s)
- María Victoria Grosso-Becera
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones, Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Escolar, Apartado Postal 70228, DF, México
| | - Luis Servín-González
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones, Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Escolar, Apartado Postal 70228, DF, México
| | - Gloria Soberón-Chávez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones, Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Escolar, Apartado Postal 70228, DF, México.
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64
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Wagner D, Rinnenthal J, Narberhaus F, Schwalbe H. Mechanistic insights into temperature-dependent regulation of the simple cyanobacterial hsp17 RNA thermometer at base-pair resolution. Nucleic Acids Res 2015; 43:5572-85. [PMID: 25940621 PMCID: PMC4477652 DOI: 10.1093/nar/gkv414] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/08/2015] [Indexed: 12/16/2022] Open
Abstract
The cyanobacterial hsp17 ribonucleicacid thermometer (RNAT) is one of the smallest naturally occurring RNAT. It forms a single hairpin with an internal 1×3-bulge separating the start codon in stem I from the ribosome binding site (RBS) in stem II. We investigated the temperature-dependent regulation of hsp17 by mapping individual base-pair stabilities from solvent exchange nuclear magnetic resonance (NMR) spectroscopy. The wild-type RNAT was found to be stabilized by two critical CG base pairs (C14-G27 and C13-G28). Replacing the internal 1×3 bulge by a stable CG base pair in hsp17rep significantly increased the global stability and unfolding cooperativity as evidenced by circular dichroism spectroscopy. From the NMR analysis, remote stabilization and non-nearest neighbour effects exist at the base-pair level, in particular for nucleotide G28 (five nucleotides apart from the side of mutation). Individual base-pair stabilities are coupled to the stability of the entire thermometer within both the natural and the stabilized RNATs by enthalpy–entropy compensation presumably mediated by the hydration shell. At the melting point the Gibbs energies of the individual nucleobases are equalized suggesting a consecutive zipper-type unfolding mechanism of the RBS leading to a dimmer-like function of hsp17 and switch-like regulation behaviour of hsp17rep. The data show how minor changes in the nucleotide sequence not only offset the melting temperature but also alter the mode of temperature sensing. The cyanobacterial thermosensor demonstrates the remarkable adjustment of natural RNATs to execute precise temperature control.
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Affiliation(s)
- Dominic Wagner
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Jörg Rinnenthal
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Franz Narberhaus
- Microbial Biology, Ruhr University, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
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65
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Oliva G, Sahr T, Buchrieser C. Small RNAs, 5′ UTR elements and RNA-binding proteins in intracellular bacteria: impact on metabolism and virulence. FEMS Microbiol Rev 2015; 39:331-349. [DOI: 10.1093/femsre/fuv022] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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66
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Duval M, Simonetti A, Caldelari I, Marzi S. Multiple ways to regulate translation initiation in bacteria: Mechanisms, regulatory circuits, dynamics. Biochimie 2015; 114:18-29. [PMID: 25792421 DOI: 10.1016/j.biochi.2015.03.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/08/2015] [Indexed: 11/15/2022]
Abstract
To adapt their metabolism rapidly and constantly in response to environmental variations, bacteria often target the translation initiation process, during which the ribosome assembles on the mRNA. Here, we review different mechanisms of regulation mediated by cis-acting elements, sRNAs and proteins, showing, when possible, their intimate connection with the translational apparatus. Indeed the ribosome itself could play a direct role in several regulatory mechanisms. Different features of the regulatory signals (sequences, structures and their positions on the mRNA) are contributing to the large variety of regulatory mechanisms. Ribosome heterogeneity, variation of individual cells responses and the spatial and temporal organization of the translation process add more layers of complexity. This hampers to define manageable set of rules for bacterial translation initiation control.
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Affiliation(s)
- Mélodie Duval
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC-CNRS, F-67084 Strasbourg, France
| | - Angelita Simonetti
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC-CNRS, F-67084 Strasbourg, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC-CNRS, F-67084 Strasbourg, France
| | - Stefano Marzi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC-CNRS, F-67084 Strasbourg, France
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67
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Narayan S, Kombrabail MH, Das S, Singh H, Chary KVR, Rao BJ, Krishnamoorthy G. Site-specific fluorescence dynamics in an RNA 'thermometer' reveals the role of ribosome binding in its temperature-sensitive switch function. Nucleic Acids Res 2014; 43:493-503. [PMID: 25477380 PMCID: PMC4288164 DOI: 10.1093/nar/gku1264] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
RNA thermometers control the translation of several heat shock and virulence genes by their temperature-sensitive structural transitions. Changes in the structure and dynamics of MiniROSE RNA, which regulates translation in the temperature range of 20–45°C, were studied by site specifically replacing seven adenine residues with the fluorescent analog, 2-aminopurine (2-AP), one at a time. Dynamic fluorescence observables of 2-AP-labeled RNAs were compared in their free versus ribosome-bound states for the first time. Noticeably, position dependence of fluorescence observables, which was prominent at 20°C, was persistent even at 45ºC, suggesting the persistence of structural integrity up to 45ºC. Interestingly, position-dependent dispersion of fluorescence lifetime and quenching constant at 45°C was ablated in ribosome-bound state, when compared to those at 20°C, underscoring loss of structural integrity at 45°C, in ribosome-bound RNA. Significant increase in the value of mean lifetime for 2-AP corresponding to Shine–Dalgarno sequences, when the temperature was raised from 20 to 45°C, to values seen in the presence of urea at 45°C was a strong indicator of melting of the 3D structure of MiniROSE RNA at 45°C, only when it was ribosome bound. Taken all together, we propose a model where we invoke that ribosome binding of the RNA thermometer critically regulates temperature sensing functions in MiniROSE RNA.
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Affiliation(s)
- Satya Narayan
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Mamta H Kombrabail
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Sudipta Das
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences, Hyderabad 500075, India
| | - Himanshu Singh
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Kandala V R Chary
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Basuthkar J Rao
- Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India
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Delvillani F, Sciandrone B, Peano C, Petiti L, Berens C, Georgi C, Ferrara S, Bertoni G, Pasini ME, Dehò G, Briani F. Tet-Trap, a genetic approach to the identification of bacterial RNA thermometers: application to Pseudomonas aeruginosa. RNA (NEW YORK, N.Y.) 2014; 20:1963-1976. [PMID: 25336583 PMCID: PMC4238360 DOI: 10.1261/rna.044354.114] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 09/10/2014] [Indexed: 06/04/2023]
Abstract
Modulation of mRNA translatability either by trans-acting factors (proteins or sRNAs) or by in cis-acting riboregulators is widespread in bacteria and controls relevant phenotypic traits. Unfortunately, global identification of post-transcriptionally regulated genes is complicated by poor structural and functional conservation of regulatory elements and by the limitations of proteomic approaches in protein quantification. We devised a genetic system for the identification of post-transcriptionally regulated genes and we applied this system to search for Pseudomonas aeruginosa RNA thermometers, a class of regulatory RNA that modulates gene translation in response to temperature changes. As P. aeruginosa is able to thrive in a broad range of environmental conditions, genes differentially expressed at 37 °C versus lower temperatures may be involved in infection and survival in the human host. We prepared a plasmid vector library with translational fusions of P. aeruginosa DNA fragments (PaDNA) inserted upstream of TIP2, a short peptide able to inactivate the Tet repressor (TetR) upon expression. The library was assayed in a streptomycin-resistant merodiploid rpsL(+)/rpsL31 Escherichia coli strain in which the dominant rpsL(+) allele, which confers streptomycin sensitivity, was repressed by TetR. PaDNA fragments conferring thermosensitive streptomycin resistance (i.e., expressing PaDNA-TIP2 fusions at 37°C, but not at 28°C) were sequenced. We identified four new putative thermosensors. Two of them were validated with conventional reporter systems in E. coli and P. aeruginosa. Interestingly, one regulates the expression of ptxS, a gene implicated in P. aeruginosa pathogenesis.
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Affiliation(s)
- Francesco Delvillani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Barbara Sciandrone
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Clelia Peano
- Istituto di Tecnologie Biomediche, CNR, 20090 Segrate, Italy
| | - Luca Petiti
- Istituto di Tecnologie Biomediche, CNR, 20090 Segrate, Italy Doctoral Program of Molecular and Translational Medicine, Università degli Studi di Milano, 20133 Milano, Italy
| | - Christian Berens
- Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Christiane Georgi
- Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Silvia Ferrara
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Giovanni Bertoni
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Maria Enrica Pasini
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Gianni Dehò
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Federica Briani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
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Righetti F, Narberhaus F. How to find RNA thermometers. Front Cell Infect Microbiol 2014; 4:132. [PMID: 25279353 PMCID: PMC4166951 DOI: 10.3389/fcimb.2014.00132] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/02/2014] [Indexed: 11/27/2022] Open
Abstract
Temperature is one of the decisive signals that a mammalian pathogen has entered its warm-blooded host. Among the many ways to register temperature changes, bacteria often use temperature-modulated structures in the untranslated region of mRNAs. In this article, we describe how such RNA thermometers (RNATs) have been discovered one by one upstream of heat shock and virulence genes in the past, and how next-generation sequencing approaches are able to reveal novel temperature-responsive RNA structures on a global scale.
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70
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RNA thermometer controls temperature-dependent virulence factor expression in Vibrio cholerae. Proc Natl Acad Sci U S A 2014; 111:14241-6. [PMID: 25228776 DOI: 10.1073/pnas.1411570111] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vibrio cholerae is the bacterium that causes the diarrheal disease cholera. The bacteria experience a temperature shift as V. cholerae transition from contaminated water at lower temperatures into the 37 °C human intestine. Within the intestine, V. cholerae express cholera toxin (CT) and toxin-coregulated pilus (TCP), two main virulence factors required for disease. CT and TCP expression is controlled by the transcriptional activator protein ToxT. We identified an RNA thermometer motif in the 5' UTR of toxT, with a fourU anti-Shine-Dalgarno (SD) element that base pairs with the SD sequence to regulate ribosome access to the mRNA. RNA probing experiments demonstrated that the fourU element allowed access to the SD sequence at 37 °C but not at 20 °C. Moreover, mutations within the fourU element (U5C, U7C) that strengthened base-pairing between the anti-SD and SD sequences prevented access to the SD sequence even at 37 °C. Translation of ToxT-FLAG from the native toxT UTR was enhanced at 37 °C, compared with 25 °C in both Escherichia coli and V. cholerae. In contrast, the U5C, U7C UTR prevented translation of ToxT-FLAG even at 37 °C. V. cholerae mutants containing the U5C, U7C UTR variant were unable to colonize the infant mouse small intestine. Our results reveal a previously unknown regulatory mechanism consisting of an RNA thermometer that controls temperature-dependent translation of toxT, facilitating V. cholerae virulence at a relevant environmental condition found in the human intestine.
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71
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Groher F, Suess B. Synthetic riboswitches - A tool comes of age. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:964-973. [PMID: 24844178 DOI: 10.1016/j.bbagrm.2014.05.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/29/2014] [Accepted: 05/08/2014] [Indexed: 12/14/2022]
Abstract
Within the last decade, it has become obvious that RNA plays an important role in regulating gene expression. This has led to a plethora of approaches aiming at exploiting the outstanding chemical properties of RNA to develop synthetic RNA regulators for conditional gene expression systems. Consequently, many different regulators have been developed to act on various stages of gene expression. They can be engineered to respond to almost any ligand of choice and are, therefore, of great interest for applications in synthetic biology. This review presents an overview of such engineered riboswitches, discusses their applicability and points out recent trends in their development. This article is part of a Special Issue entitled: Riboswitches.
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Affiliation(s)
- Florian Groher
- Department of Biology, Technical University Darmstadt, 64287 Darmstadt, Germany
| | - Beatrix Suess
- Department of Biology, Technical University Darmstadt, 64287 Darmstadt, Germany.
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72
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Churkin A, Avihoo A, Shapira M, Barash D. RNAthermsw: direct temperature simulations for predicting the location of RNA thermometers. PLoS One 2014; 9:e94340. [PMID: 24718440 PMCID: PMC3981793 DOI: 10.1371/journal.pone.0094340] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 03/14/2014] [Indexed: 11/18/2022] Open
Abstract
The mechanism of RNA thermometers is a subject of growing interest. Also known as RNA thermosensors, these temperature-sensitive segments of the mRNA regulate gene expression by changing their secondary structure in response to temperature fluctuations. The detection of RNA thermometers in various genes of interest is valuable as it could lead to the discovery of new thermometers participating in fundamental processes such as preferential translation during heat-shock. RNAthermsw is a user-friendly webserver for predicting the location of RNA thermometers using direct temperature simulations. It operates by analyzing dotted figures generated as a result of a moving window that performs successive energy minimization folding predictions. Inputs include the RNA sequence, window size, and desired temperature change. RNAthermsw can be freely accessed at http://www.cs.bgu.ac.il/~rnathemsw/RNAthemsw/ (with the slash sign at the end). The website contains a help page with explanations regarding the exact usage.
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Affiliation(s)
- Alexander Churkin
- Department of Computer Science, Ben-Gurion University, Beer-Sheva, Israel
| | | | - Michal Shapira
- Department of Life Sciences, Ben-Gurion University, Beer-Sheva, Israel
| | - Danny Barash
- Department of Computer Science, Ben-Gurion University, Beer-Sheva, Israel
- * E-mail:
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73
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Cimdins A, Klinkert B, Aschke-Sonnenborn U, Kaiser FM, Kortmann J, Narberhaus F. Translational control of small heat shock genes in mesophilic and thermophilic cyanobacteria by RNA thermometers. RNA Biol 2014; 11:594-608. [PMID: 24755616 PMCID: PMC4152365 DOI: 10.4161/rna.28648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cyanobacteria constitute a heterogeneous phylum of oxygen-producing, photosynthetic prokaryotes. They are susceptible to various stress conditions like heat, salt, or light stress, all inducing the cyanobacterial heat shock response (HSR). Cyanobacterial small heat shock proteins (sHsps) are known to preserve thylakoid membrane integrity under stress conditions, thereby protecting the photosynthesis machinery. In Synechocystis sp PCC 6803, synthesis of the sHsp Hsp17 is regulated by an RNA thermometer (RNAT) in the 5′-untranslated region (5′-UTR) of the hsp17 mRNA. RNATs are direct temperature sensors that control expression of many bacterial heat shock and virulence genes. They hinder translation at low temperatures by base pairing, thus blocking ribosome access to the mRNA.
To explore the temperature range in which RNATs act, we studied various RNAT candidates upstream of sHsp genes from mesophilic and thermophilic cyanobacteria. The mesophilic cyanobacteria Anabaena variabilis and Nostoc sp chromosomally encode two sHsps each. Reporter gene studies suggested RNAT-mediated post-transcriptional regulation of shsp expression in both organisms. Detailed structural analysis of the two A. variabilis candidates revealed two novel RNAT types. The first, avashort, regulates translation primarily by masking of the AUG translational start codon. The second, featuring an extended initial hairpin, thus named avalong, presumably makes use of complex tertiary interaction. The 5′-UTR of the small heat shock gene hspA in the thermophile Thermosynechococcus elongatus is predicted to adopt an extended secondary structure. Structure probing revealed that the ribosome binding site was blocked at temperatures below 55 °C. The results of this study demonstrate that cyanobacteria commonly use RNATs to control expression of their small heat shock genes.
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Affiliation(s)
- Annika Cimdins
- Microbial Biology; Ruhr University Bochum; Bochum, Germany
| | | | | | | | - Jens Kortmann
- Microbial Biology; Ruhr University Bochum; Bochum, Germany
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Krajewski SS, Joswig M, Nagel M, Narberhaus F. A tricistronic heat shock operon is important for stress tolerance of Pseudomonas putida and conserved in many environmental bacteria. Environ Microbiol 2014; 16:1835-53. [PMID: 24612349 DOI: 10.1111/1462-2920.12432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 02/13/2014] [Indexed: 11/28/2022]
Abstract
Small heat shock proteins (sHsps) including the well-studied IbpA protein from Escherichia coli are molecular chaperones that bind to non-native proteins and prevent them from aggregation. We discovered an entirely unexplored tricistronic small heat shock gene cluster in Pseudomonas putida. The genes pp3314, pp3313 and pp3312 (renamed to hspX, hspY and hspZ respectively) are transcribed in a single transcript. In addition to σ(32) -dependent transcriptional control, translation of the first and second gene of the operon is controlled by RNA thermometers with novel architectures. Biochemical analysis of HspY, HspZ and P. putida IbpA demonstrated that they assemble into homo-oligomers of different sizes whose quaternary structures alter in a temperature-dependent manner. IbpA and HspY are able to prevent the model substrate citrate synthase from thermal aggregation in vitro. Increased stress sensitivity of a P. putida strain lacking HspX, HspY and HspZ revealed an important role of these sHsps in stress adaptation. The hspXYZ operon is conserved among metabolically related bacteria that live in hostile environments including polluted soils. This heat shock operon might act as a protective system to promote survival in such ecological niches.
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75
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Krajewski SS, Narberhaus F. Temperature-driven differential gene expression by RNA thermosensors. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:978-988. [PMID: 24657524 DOI: 10.1016/j.bbagrm.2014.03.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/28/2014] [Accepted: 03/14/2014] [Indexed: 12/20/2022]
Abstract
Many prokaryotic genes are organized in operons. Genes organized in such transcription units are co-transcribed into a polycistronic mRNA. Despite being clustered in a single mRNA, individual genes can be subjected to differential regulation, which is mainly achieved at the level of translation depending on initiation and elongation. Efficiency of translation initiation is primarily determined by the structural accessibility of the ribosome binding site (RBS). Structured cis-regulatory elements like RNA thermometers (RNATs) can contribute to differential regulation of individual genes within a polycistronic mRNA. RNATs are riboregulators that mediate temperature-responsive regulation of a downstream gene by modulating the accessibility of its RBS. At low temperature, the RBS is trapped by intra-molecular base pairing prohibiting translation initiation. The secondary structure melts with increasing temperature thus liberating the RBS. Here, we present an overview of different RNAT types and specifically highlight recently discovered RNATs. The main focus of this review is on RNAT-based differential control of polycistronic operons. Finally, we discuss the influence of temperature on other riboregulators and the potential of RNATs in synthetic RNA biology. This article is part of a Special Issue entitled: Riboswitches.
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76
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Han Y, Liu L, Fang N, Yang R, Zhou D. Regulation of pathogenicity by noncoding RNAs in bacteria. Future Microbiol 2013; 8:579-91. [PMID: 23642114 DOI: 10.2217/fmb.13.20] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Regulatory noncoding RNAs (ncRNAs) play important roles in bacterial gene regulation, primarily at the post-transcriptional level. There are four broad categories of regulatory ncRNAs including trans-encoded ncRNAs, cis-encoded ncRNAs, RNA thermometers and riboswitches, and they can influence the translation and/or stability of mRNAs by binding to the base-pairing sites in their target transcripts. In pathogenic bacteria, numerous ncRNAs are involved in the coordinated expression of virulence determinants to facilitate the pathogenicity in a concerted manner. This review discusses the modes of action of different regulatory ncRNAs and, furthermore, exemplifies their roles in regulating bacterial pathogenicity.
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Affiliation(s)
- Yanping Han
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Beijing 100071, China
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77
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Limanskaya OY, Murtazaeva LA, Limanskii AP. Potential thermosensitive riboswitches in the genome of Salmonella. CYTOL GENET+ 2013; 47:268-275. [PMID: 32214543 PMCID: PMC7089174 DOI: 10.3103/s009545271305006x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Indexed: 11/30/2022]
Abstract
Currently, a number of structurally and functionally different thermosensitive elements, such as structurally and functionally different RNA thermometers, for controlling a variety of biological processes in bacteria, including virulence are known. These well-known RNA thermometers are structures, whether matched or mismatched, which are represented by either a single stretched hairpin structure or a few hairpins. Based on computer and thermodynamic analyses of 25 isolates of Salmonella enterica with complete genome, we have developed an algorithm and criteria to search for potential RNA thermometers, which will enable us to undertake a future search for potential riboswitches in the genomes of other socially significant pathogens. In addition to the well-known 4U RNA thermometer, another four hairpin-loop structures have been identified in S. enterica as new potential RNA thermometers and two of them are localized in 5'-UTR of virulence regulators gltB and yaeQ. They are highly conserved noncanonical structures and correspond to the necessary and sufficient conditions for forming RNA thermometers, since they are found in each of the 25 S. enterica genome isolates. We analyzed the thermosensitive motif in the pXO1 plasmid of Bacillus anthracis-an anthrax-causative pathogen-and visualized matched hairpins that form a cruciform structure in pUC8 supercoiled plasmid by atomic force microscopy.
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Affiliation(s)
- O. Yu. Limanskaya
- Mechnikov Institute of Microbiology and Immunology, National Academy of Medical Sciences of Ukraine, Kharkov, Ukraine
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, National Academy of Medical Sciences of Ukraine, Kharkov, Ukraine
| | | | - A. P. Limanskii
- Mechnikov Institute of Microbiology and Immunology, National Academy of Medical Sciences of Ukraine, Kharkov, Ukraine
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78
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Role for cis-acting RNA sequences in the temperature-dependent expression of the multiadhesive lig proteins in Leptospira interrogans. J Bacteriol 2013; 195:5092-101. [PMID: 24013626 DOI: 10.1128/jb.00663-13] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The spirochete Leptospira interrogans causes a systemic infection that provokes a febrile illness. The putative lipoproteins LigA and LigB promote adhesion of Leptospira to host proteins, interfere with coagulation, and capture complement regulators. In this study, we demonstrate that the expression level of the LigA and LigB proteins was substantially higher when L. interrogans proliferated at 37°C instead of the standard culture temperature of 30°C. The RNA comprising the 175-nucleotide 5' untranslated region (UTR) and first six lig codons, whose sequence is identical in ligA and ligB, is predicted to fold into two distinct stem-loop structures separated by a single-stranded region. The ribosome-binding site is partially sequestered in double-stranded RNA within the second structure. Toeprint analysis revealed that in vitro formation of a 30S-tRNA(fMet)-mRNA ternary complex was inhibited unless a 5' deletion mutation disrupted the second stem-loop structure. To determine whether the lig sequence could mediate temperature-regulated gene expression in vivo, the 5' UTR and the first six codons were inserted between the Escherichia coli l-arabinose promoter and bgaB (β-galactosidase from Bacillus stearothermophilus) to create a translational fusion. The lig fragment successfully conferred thermoregulation upon the β-galactosidase reporter in E. coli. The second stem-loop structure was sufficient to confer thermoregulation on the reporter, while sequences further upstream in the 5' UTR slightly diminished expression at each temperature tested. Finally, the expression level of β-galactosidase was significantly higher when point mutations predicted to disrupt base pairs in the second structure were introduced into the stem. Compensatory mutations that maintained base pairing of the stem without restoring the wild-type sequence reinstated the inhibitory effect of the 5' UTR on expression. These results indicate that ligA and ligB expression is limited by double-stranded RNA that occludes the ribosome-binding site. At elevated temperatures, the ribosome-binding site is exposed to promote translation initiation.
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79
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Cimdins A, Roßmanith J, Langklotz S, Bandow JE, Narberhaus F. Differential control of Salmonella heat shock operons by structured mRNAs. Mol Microbiol 2013; 89:715-31. [PMID: 23802546 DOI: 10.1111/mmi.12308] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2013] [Indexed: 12/29/2022]
Abstract
DnaK-DnaJ-GrpE and GroES-GroEL are the major chaperone machineries in bacteria. In many species, dnaKJ and groESL are encoded in bicistronic operons. Quantitative proteomics revealed that DnaK and GroEL amounts in Salmonella dominate over DnaJ and GroES respectively. An imperfect transcriptional terminator in the intergenic region of dnaKJ is known to result in higher transcript levels of the first gene. Here, we examined the groESL operon and asked how the second gene in a heat shock operon can be preferentially expressed and found that an RNA structure in the 5'untranslated region of groES is responsible. The secondary structure masks the Shine-Dalgarno (SD) sequence and AUG start codon and thereby modulates translation of groES mRNA. Reporter gene assays combined with structure probing and toeprinting analysis revealed a dynamic temperature-sensitive RNA structure. Following an increase in temperature, only the second of two RNA hairpins melts and partially liberates the SD sequence, thus facilitating translation. Translation of groEL is not temperature-regulated leading to an excess of the chaperonin in the cell at low temperature. Discussion in a broader context shows how structured RNA segments can differentially control expression of temperature-affected operons in various ways.
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Affiliation(s)
- Annika Cimdins
- Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780 Bochum, Germany
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80
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Steinmann R, Dersch P. Thermosensing to adjust bacterial virulence in a fluctuating environment. Future Microbiol 2013; 8:85-105. [PMID: 23252495 DOI: 10.2217/fmb.12.129] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The lifecycle of most microbial pathogens can be divided into two states: existence outside and inside their hosts. The sudden temperature upshift experienced upon entry from environmental or vector reservoirs into a warm-blooded host is one of the most crucial signals informing the pathogens to adjust virulence gene expression and their host-stress survival program. This article reviews the plethora of sophisticated strategies that bacteria have evolved to sense temperature, and outlines the molecular signal transduction mechanisms used to modulate synthesis of crucial virulence determinants. The molecular details of thermal control through conformational changes of DNA, RNA and proteins are summarized, complex and diverse thermosensing principles are introduced and their potential as drug targets or synthetic tools are discussed.
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Affiliation(s)
- Rebekka Steinmann
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
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81
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Krajewski SS, Nagel M, Narberhaus F. Short ROSE-like RNA thermometers control IbpA synthesis in Pseudomonas species. PLoS One 2013; 8:e65168. [PMID: 23741480 PMCID: PMC3669281 DOI: 10.1371/journal.pone.0065168] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 04/22/2013] [Indexed: 11/18/2022] Open
Abstract
The bacterial small heat shock protein IbpA protects client proteins from aggregation. Due to redundancy in the cellular chaperone network, deletion of the ibpA gene often leads to only a mild or no phenotypic defect. In this study, we show that a Pseudomonas putida ibpA deletion mutant has a severe growth defect under heat stress conditions and reduced survival during recovery revealing a critical role of IbpA in heat tolerance. Transcription of the ibpA gene depends on the alternative heat shock sigma factor σ32. Production of IbpA protein only at heat shock temperatures suggested additional translational control. We conducted a comprehensive structural and functional analysis of the 5′ untranslated regions of the ibpA genes from P. putida and Pseudomonas aeruginosa. Both contain a ROSE-type RNA thermometer that is substantially shorter and simpler than previously reported ROSE elements. Comprised of two hairpin structures only, they inhibit translation at low temperature and permit translation initiation after a temperature upshift. Both elements regulate reporter gene expression in Escherichia coli and ribosome binding in vitro in a temperature-dependent manner. Structure probing revealed local melting of the second hairpin whereas the first hairpin remained unaffected. High sequence and structure conservation of pseudomonal ibpA untranslated regions and their ability to confer thermoregulation in vivo suggest that short ROSE-like thermometers are commonly used to control IbpA synthesis in Pseudomonas species.
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Affiliation(s)
| | - Miriam Nagel
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Franz Narberhaus
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
- * E-mail:
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82
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RNA-mediated thermoregulation of iron-acquisition genes in Shigella dysenteriae and pathogenic Escherichia coli. PLoS One 2013; 8:e63781. [PMID: 23704938 PMCID: PMC3660397 DOI: 10.1371/journal.pone.0063781] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/07/2013] [Indexed: 12/29/2022] Open
Abstract
The initiation, progression and transmission of most bacterial infections is dependent upon the ability of the invading pathogen to acquire iron from each of the varied environments encountered during the course of a natural infection. In total, 95% of iron within the human body is complexed within heme, making heme a potentially rich source of host-associated nutrient iron for invading bacteria. As heme is encountered only within the host, pathogenic bacteria often regulate synthesis of heme utilization factors such that production is maximal under host-associated environmental conditions. This study examines the regulated production of ShuA, an outer-membrane receptor required for the utilization of heme as a source of nutrient iron by Shigella dysenteriae, a pathogenic bacterium that causes severe diarrheal diseases in humans. Specifically, the impact of the distinct environmental temperatures encountered during infection within a host (37°C) and transmission between hosts (25°C) on shuA expression is investigated. We show that shuA expression is subject to temperature-dependent post-transcriptional regulation resulting in increased ShuA production at 37°C. The observed thermoregulation is mediated by nucleic acid sequences within the 5' untranslated region. In addition, we have identified similar nucleotide sequences within the 5' untranslated region of the orthologous chuA transcript of enteropathogenic E. coli and have demonstrated that it also functions to confer temperature-dependent post-transcriptional regulation. In both function and predicted structure, the regulatory element within the shuA and chuA 5' untranslated regions closely resembles a FourU RNA thermometer, a zipper-like RNA structure that occludes the Shine-Dalgarno sequence at low temperatures. Increased production of ShuA and ChuA in response to the host body temperature allows for maximal production of these heme acquisition factors within the environment where S. dysenteriae and pathogenic E. coli strains would encounter heme, a host-specific iron source.
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83
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Hoe CH, Raabe CA, Rozhdestvensky TS, Tang TH. Bacterial sRNAs: regulation in stress. Int J Med Microbiol 2013; 303:217-29. [PMID: 23660175 DOI: 10.1016/j.ijmm.2013.04.002] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 03/26/2013] [Accepted: 04/07/2013] [Indexed: 11/28/2022] Open
Abstract
Bacteria are often exposed to a hostile environment and have developed a plethora of cellular processes in order to survive. A burgeoning list of small non-coding RNAs (sRNAs) has been identified and reported to orchestrate crucial stress responses in bacteria. Among them, cis-encoded sRNA, trans-encoded sRNA, and 5'-untranslated regions (UTRs) of the protein coding sequence are influential in the bacterial response to environmental cues, such as fluctuation of temperature and pH as well as other stress conditions. This review summarizes the role of bacterial sRNAs in modulating selected stress conditions and highlights the alliance between stress response and clustered regularly interspaced short palindromic repeats (CRISPR) in bacterial defense.
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Affiliation(s)
- Chee-Hock Hoe
- Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia, Kepala Batas, 13200 Penang, Malaysia.
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84
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Saragliadis A, Krajewski SS, Rehm C, Narberhaus F, Hartig JS. Thermozymes: Synthetic RNA thermometers based on ribozyme activity. RNA Biol 2013; 10:1010-6. [PMID: 23595083 DOI: 10.4161/rna.24482] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Synthetic biology approaches often combine natural building blocks to generate new cellular activities. Here, we make use of two RNA elements to design a regulatory device with novel functionality. The system is based on a hammerhead ribozyme (HHR) that cleaves itself to generate a liberated ribosome-binding site and, thus, permits expression of a downstream gene. We connected a temperature-responsive RNA hairpin to the HHR and, thus, generated a temperature-controlled ribozyme that we call thermozyme. Specifically, a Salmonella RNA thermometer (RNAT) known to modulate small heat shock gene expression by temperature-controlled base-pairing and melting was fused to the ribozyme. Following an in vivo screening approach, we isolated two functional thermozymes. In vivo expression studies and in vitro structure probing experiments support a mechanism in which rising temperatures melt the thermometer structure impairing the self-cleavage reaction of the ribozyme. Since RNA cleavage is necessary to liberate the RBS, these engineered thermozymes shut off gene expression in response to a temperature increase and, thus, act in a reverse manner as the natural RNAT. Our results clearly emphasize the highly modular nature and biotechnological potential of ribozyme-based RNA thermometers.
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Affiliation(s)
- Athanasios Saragliadis
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
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85
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Barquist L, Langridge GC, Turner DJ, Phan MD, Turner AK, Bateman A, Parkhill J, Wain J, Gardner PP. A comparison of dense transposon insertion libraries in the Salmonella serovars Typhi and Typhimurium. Nucleic Acids Res 2013; 41:4549-64. [PMID: 23470992 PMCID: PMC3632133 DOI: 10.1093/nar/gkt148] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Salmonella Typhi and Typhimurium diverged only ∼50 000 years ago, yet have very different host ranges and pathogenicity. Despite the availability of multiple whole-genome sequences, the genetic differences that have driven these changes in phenotype are only beginning to be understood. In this study, we use transposon-directed insertion-site sequencing to probe differences in gene requirements for competitive growth in rich media between these two closely related serovars. We identify a conserved core of 281 genes that are required for growth in both serovars, 228 of which are essential in Escherichia coli. We are able to identify active prophage elements through the requirement for their repressors. We also find distinct differences in requirements for genes involved in cell surface structure biogenesis and iron utilization. Finally, we demonstrate that transposon-directed insertion-site sequencing is not only applicable to the protein-coding content of the cell but also has sufficient resolution to generate hypotheses regarding the functions of non-coding RNAs (ncRNAs) as well. We are able to assign probable functions to a number of cis-regulatory ncRNA elements, as well as to infer likely differences in trans-acting ncRNA regulatory networks.
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Affiliation(s)
- Lars Barquist
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK.
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86
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Limanskaya OY, Murtazaeva LA, Limanskii AP. Search for the new potential RNA thermometers in the genome of Salmonella enterica. Microbiology (Reading) 2013; 82:68-76. [PMID: 32214462 PMCID: PMC7089039 DOI: 10.1134/s0026261713010062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Indexed: 11/22/2022] Open
Abstract
Currently, a number of structurally and functionally different temperature-sensitive elements such as RNA thermometers which control a variety of biological processes in bacteria, including virulence, are known. Based on computer and thermodynamic analysis of completely sequenced genomes of 25 Salmonella enterica isolates, the algorithm and criteria for the search of potential RNA thermometers were developed. It will make it possible to carry out the search for potential riboswitches in the genome of other socially important pathogens. For S. enterica, apart from the known 4U RNA thermometer, four hairpin-loop structures were identified which may probably act as additional RNA thermometers. They satisfy the necessary and sufficient conditions for formation of RNA thermometers and are highly conservative uncanonical structures, since these highly conservative structures were found in the genome of all 25 isolates of S. enterica. The hairpins forming a cruciform structure in the supercoiled pUC8 DNA were visualized by atomic force microscopy.
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Affiliation(s)
- O. Yu. Limanskaya
- Mechnikov Institute of Microbiology and Immunology, National Academy of Medical Sciences of Ukraine, Kharkov, Ukraine
- Institute of Experimental and Clinical Veterinary Medicine, National Academy of Agricultural Sciences of Ukraine, Kharkov, Ukraine
| | | | - A. P. Limanskii
- Mechnikov Institute of Microbiology and Immunology, National Academy of Medical Sciences of Ukraine, Kharkov, Ukraine
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87
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Wachsmuth M, Findeiß S, Weissheimer N, Stadler PF, Mörl M. De novo design of a synthetic riboswitch that regulates transcription termination. Nucleic Acids Res 2012; 41:2541-51. [PMID: 23275562 PMCID: PMC3575828 DOI: 10.1093/nar/gks1330] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Riboswitches are regulatory RNA elements typically located in the 5′-untranslated region of certain mRNAs and control gene expression at the level of transcription or translation. These elements consist of a sensor and an adjacent actuator domain. The sensor usually is an aptamer that specifically interacts with a ligand. The actuator contains an intrinsic terminator or a ribosomal binding site for transcriptional or translational regulation, respectively. Ligand binding leads to structural rearrangements of the riboswitch and to presentation or masking of these regulatory elements. Based on this modular organization, riboswitches are an ideal target for constructing synthetic regulatory systems for gene expression. Although riboswitches for translational control have been designed successfully, attempts to construct synthetic elements regulating transcription have failed so far. Here, we present an in silico pipeline for the rational design of synthetic riboswitches that regulate gene expression at the transcriptional level. Using the well-characterized theophylline aptamer as sensor, we designed the actuator part as RNA sequences that can fold into functional intrinsic terminator structures. In the biochemical characterization, several of the designed constructs show ligand-dependent control of gene expression in Escherichia coli, demonstrating that it is possible to engineer riboswitches not only for translational but also for transcriptional regulation.
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Affiliation(s)
- Manja Wachsmuth
- Institute for Biochemistry, University of Leipzig, Brüderstr. 34, 04103 Leipzig, Germany
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88
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ncRNAs and thermoregulation: a view in prokaryotes and eukaryotes. FEBS Lett 2012; 586:4061-9. [PMID: 23098758 DOI: 10.1016/j.febslet.2012.10.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/09/2012] [Accepted: 10/10/2012] [Indexed: 11/24/2022]
Abstract
During cellular stress response, a widespread inhibition of transcription and blockade of splicing and other post-transcriptional processing is detected, while certain specific genes are induced. In particular, free-living cells constantly monitor temperature. When the thermal condition changes, they activate a set of genes coding for proteins that participate in the response. Non-coding RNAs, ncRNAs, and conformational changes in specific regions of mRNAs seem also to be crucial regulators that enable the cell to adjust its physiology to environmental changes. They exert their effects following the same principles in all organisms and may affect all steps of gene expression. These ncRNAs and structural elements as related to thermal stress response in bacteria are reviewed. The resemblances to eukaryotic ncRNAs are highlighted.
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89
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Shapiro RS, Cowen LE. Thermal control of microbial development and virulence: molecular mechanisms of microbial temperature sensing. mBio 2012; 3:e00238-12. [PMID: 23033469 PMCID: PMC3518907 DOI: 10.1128/mbio.00238-12] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Temperature is a critical and ubiquitous environmental signal that governs the development and virulence of diverse microbial species, including viruses, archaea, bacteria, fungi, and parasites. Microbial survival is contingent upon initiating appropriate responses to the cellular stress induced by severe environmental temperature change. In the case of microbial pathogens, development and virulence are often coupled to sensing host physiological temperatures. As such, microbes have developed diverse molecular strategies to sense fluctuations in temperature, and nearly all cellular molecules, including proteins, lipids, RNA, and DNA, can act as thermosensors that detect changes in environmental temperature and initiate relevant cellular responses. The myriad of molecular mechanisms by which microbes sense and respond to temperature reveals an elegant repertoire of strategies to orchestrate cellular signaling, developmental programs, and virulence with spatial and temporal environmental cues.
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Affiliation(s)
- Rebecca S Shapiro
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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90
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91
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Concerted actions of a thermo-labile regulator and a unique intergenic RNA thermosensor control Yersinia virulence. PLoS Pathog 2012; 8:e1002518. [PMID: 22359501 PMCID: PMC3280987 DOI: 10.1371/journal.ppat.1002518] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 12/19/2011] [Indexed: 11/19/2022] Open
Abstract
Expression of all Yersinia pathogenicity factors encoded on the virulence plasmid, including the yop effector and the ysc type III secretion genes, is controlled by the transcriptional activator LcrF in response to temperature. Here, we show that a protein- and RNA-dependent hierarchy of thermosensors induce LcrF synthesis at body temperature. Thermally regulated transcription of lcrF is modest and mediated by the thermo-sensitive modulator YmoA, which represses transcription from a single promoter located far upstream of the yscW-lcrF operon at moderate temperatures. The transcriptional response is complemented by a second layer of temperature-control induced by a unique cis-acting RNA element located within the intergenic region of the yscW-lcrF transcript. Structure probing demonstrated that this region forms a secondary structure composed of two stemloops at 25°C. The second hairpin sequesters the lcrF ribosomal binding site by a stretch of four uracils. Opening of this structure was favored at 37°C and permitted ribosome binding at host body temperature. Our study further provides experimental evidence for the biological relevance of an RNA thermometer in an animal model. Following oral infections in mice, we found that two different Y. pseudotuberculosis patient isolates expressing a stabilized thermometer variant were strongly reduced in their ability to disseminate into the Peyer's patches, liver and spleen and have fully lost their lethality. Intriguingly, Yersinia strains with a destabilized version of the thermosensor were attenuated or exhibited a similar, but not a higher mortality. This illustrates that the RNA thermometer is the decisive control element providing just the appropriate amounts of LcrF protein for optimal infection efficiency.
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92
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Klinkert B, Cimdins A, Gaubig LC, Roßmanith J, Aschke-Sonnenborn U, Narberhaus F. Thermogenetic tools to monitor temperature-dependent gene expression in bacteria. J Biotechnol 2012; 160:55-63. [PMID: 22285954 DOI: 10.1016/j.jbiotec.2012.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 12/29/2011] [Accepted: 01/12/2012] [Indexed: 10/14/2022]
Abstract
Free-living bacteria constantly monitor their ambient temperature. Drastic deviations elicit immediate protective responses known as cold shock or heat shock response. Many mammalian pathogens use temperature surveillance systems to recognize the successful invasion of a host by its body temperature, usually 37°C. Translation of temperature-responsive genes can be modulated by RNA thermometers (RNATs). RNATs form complex structures primarily in the 5'-untranslated region of their transcripts. Most RNATs block the ribosome binding site at low temperatures. Translation is induced at increasing temperature by melting of the RNA structure. The analysis of such temperature-dependent RNA elements calls for adequate test systems that function in the appropriate temperature range. Here, we summarize previously established reporter gene systems based on the classical β-galactosidase LacZ, the heat-stable β-galactosidase BgaB and the green fluorescent protein GFP. We validate these systems by testing known RNATs and describe the construction and application of an optimized bgaB system. Finally, two novel RNA thermometer candidates from Escherichia coli and Salmonella will be presented.
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Affiliation(s)
- Birgit Klinkert
- Microbial Biology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
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93
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Miyagawa R, Mizuno R, Watanabe K, Ijiri K. Formation of tRNA granules in the nucleus of heat-induced human cells. Biochem Biophys Res Commun 2012; 418:149-55. [PMID: 22244871 DOI: 10.1016/j.bbrc.2011.12.150] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 12/30/2011] [Indexed: 10/14/2022]
Abstract
The stress response, which can trigger various physiological phenomena, is important for living organisms. For instance, a number of stress-induced granules such as P-body and stress granule have been identified. These granules are formed in the cytoplasm under stress conditions and are associated with translational inhibition and mRNA decay. In the nucleus, there is a focus named nuclear stress body (nSB) that distinguishes these structures from cytoplasmic stress granules. Many splicing factors and long non-coding RNA species localize in nSBs as a result of stress. Indeed, tRNAs respond to several kinds of stress such as heat, oxidation or starvation. Although nuclear accumulation of tRNAs occurs in starved Saccharomyces cerevisiae, this phenomenon is not found in mammalian cells. We observed that initiator tRNA(Met) (Meti) is actively translocated into the nucleus of human cells under heat stress. During this study, we identified unique granules of Meti that overlapped with nSBs. Similarly, elongator tRNA(Met) was translocated into the nucleus and formed granules during heat stress. Formation of tRNA granules is closely related to the translocation ratio. Then, all tRNAs may form the specific granules.
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Affiliation(s)
- Ryu Miyagawa
- Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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94
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Abstract
Four different mechanisms have evolved in eubacteria to comply with changes in the environmental temperature. The underlying genetic mechanisms regulate gene expression at transcriptional, translational and posttranslational level. The high temperature response (HTR) is a reaction on increases in temperature and is mainly used by pathogenic bacteria when they enter their mammalian host. The temperature of 37°C causes induction of the virulent genes the products of which are only needed in this environment. The heat shock response (HSR) is induced by any sudden increase in temperature, allows the bacterial cell to adapt to this environmental stress factor and is shut off after adaptation. In a similar way the low temperature response (LTR) is a reaction to a new environment and leads to the constant expression of appropriate genes. In contrast, the cold shock response (CSR) includes turn off of the cold shock genes after adaptation to the low temperature. Sensors of temperature changes are specific DNA regions, RNA molecules or proteins and conformational changes have been identified as a common motif.
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95
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Rinnenthal J, Buck J, Ferner J, Wacker A, FÜrtig B, Schwalbe H. Mapping the landscape of RNA dynamics with NMR spectroscopy. Acc Chem Res 2011; 44:1292-301. [PMID: 21894962 DOI: 10.1021/ar200137d] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Among the three major classes of biomacromolecules (DNA, RNA, and proteins) RNA's pronounced dynamics are the most explicitly linked to its wide variety of functions, which include catalysis and the regulation of transcription, translation, and splicing. These functions are mediated by a range of RNA biomachinery, including such varied examples as macromolecular noncoding RNAs, microRNAs, small interfering RNAs, riboswitch RNAs, and RNA thermometers. In each case, the functional dynamics of an interconversion is characterized by an associated rate constant. In this Account, we provide an introduction to NMR spectroscopic characterization of the landscape of RNA dynamics. We introduce strategies for measuring NMR parameters at various time scales as well as the underlying models for describing the corresponding rate constants. RNA exhibits significant dynamic motion, which can be modulated by (i) intermolecular interactions, including specific and nonspecific binding of ions (such as Mg(2+) and tertiary amines), (ii) metabolites in riboswitches or RNA aptamers, and (iii) macromolecular interactions within ribonucleic protein particles, including the ribosome and the spliceosome. Our understanding of the nature of these dynamic changes in RNA targets is now being incorporated into RNA-specific approaches in the design of RNA inhibitors. Interactions of RNA with proteins, other RNAs, or small molecules often occur through binding mechanisms that follow an induced fit mechanism or a conformational selection mechanism, in which one of several populated RNA conformations is selected through ligand binding. The extent of functional dynamics, including the kinetic formation of a specific RNA tertiary fold, is dependent on the messenger RNA (mRNA) chain length. Thus, during de novo synthesis of mRNA, both in prokaryotes and eukaryotes, nascent mRNA of various lengths will adopt different secondary and tertiary structures. The speed of transcription has a critical influence on the functional dynamics of the RNA being synthesized. In addition to modulating the local dynamics of a conformational RNA ensemble, a given RNA sequence may adopt more than one global, three-dimensional structure. RNA modification is one way to select among these alternative structures, which are often characterized by nearly equal stability, but with high energy barriers for conformational interconversion. The refolding of different secondary and tertiary structures has been found to be a major regulatory mechanism for transcription and translation. These conformational transitions can be characterized with NMR spectroscopy, for any given RNA sequence, in response to external stimuli.
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Affiliation(s)
- Jörg Rinnenthal
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Janina Buck
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Jan Ferner
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Boris FÜrtig
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main, Germany
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96
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Rinnenthal J, Klinkert B, Narberhaus F, Schwalbe H. Modulation of the stability of the Salmonella fourU-type RNA thermometer. Nucleic Acids Res 2011; 39:8258-70. [PMID: 21727085 PMCID: PMC3185406 DOI: 10.1093/nar/gkr314] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 04/19/2011] [Accepted: 04/19/2011] [Indexed: 11/15/2022] Open
Abstract
RNA thermometers are translational control elements that regulate the expression of bacterial heat shock and virulence genes. They fold into complex secondary structures that block translation at low temperatures. A temperature increase releases the ribosome binding site and thus permits translation initiation. In fourU-type RNA thermometers, the AGGA sequence of the SD region is paired with four consecutive uridines. We investigated the melting points of the wild-type and mutant sequences. It was decreased by 5°C when a stabilizing GC basepair was exchanged by an AU pair or increased by 11°C when an internal AG mismatch was converted to a GC pair, respectively. Stabilized or destabilized RNA structures are directly correlated with decreased or increased in vivo gene expression, respectively. Mg(2+) also affected the melting point of the fourU thermometer. Variations of the Mg(2+) concentration in the physiological range between 1 and 2 mM translated into a 2.8°C shift of the melting point. Thus, Mg(2+) binding to the hairpin RNA is regulatory relevant. Applying three different NMR techniques, two Mg(2+) binding sites were found in the hairpin structure. One of these binding sites could be identified as outer sphere binding site that is located within the fourU motif. Binding of the two Mg(2+) ions exhibits a positive cooperativity with a Hill coefficient of 1.47. Free energy values ΔG for Mg(2+) binding determined by NMR are in agreement with data determined from CD measurements.
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Affiliation(s)
- Jörg Rinnenthal
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
| | - Birgit Klinkert
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
| | - Franz Narberhaus
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 7, D-60438 Frankfurt/Main and Microbial Biology, Ruhr-Universität Bochum, Universitätsstrasse 150, NDEF06/783, 44780 Bochum, Germany
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97
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Wan Y, Kertesz M, Spitale RC, Segal E, Chang HY. Understanding the transcriptome through RNA structure. Nat Rev Genet 2011; 12:641-55. [PMID: 21850044 DOI: 10.1038/nrg3049] [Citation(s) in RCA: 325] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
RNA structure is crucial for gene regulation and function. In the past, transcriptomes have largely been parsed by primary sequences and expression levels, but it is now becoming feasible to annotate and compare transcriptomes based on RNA structure. In addition to computational prediction methods, the recent advent of experimental techniques to probe RNA structure by high-throughput sequencing has enabled genome-wide measurements of RNA structure and has provided the first picture of the structural organization of a eukaryotic transcriptome - the 'RNA structurome'. With additional advances in method refinement and interpretation, structural views of the transcriptome should help to identify and validate regulatory RNA motifs that are involved in diverse cellular processes and thereby increase understanding of RNA function.
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Affiliation(s)
- Yue Wan
- Howard Hughes Medical Institute and Program in Epithelial Biology, Stanford University School of Medicine, Stanford, California 94305, USA
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98
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Biggs PJ, Collins LJ. RNA networks in prokaryotes I: CRISPRs and riboswitches. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 722:209-20. [PMID: 21915791 DOI: 10.1007/978-1-4614-0332-6_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
As with eukaryotes, prokaryotes employ a variety of mechanisms to allow the various types of RNA to interact and perform complex functions as a network. This chapter will detail prokaryotic molecular systems, such as riboswitches and CRISPRs, to show how they perform unique functions within the cell. These systems can interact with each other to gain a higher level of control and here we highlight some examples of such interactions including the cleavage of certain riboswitches by RNaseP, and endoribonuclease cleavage of pre-crRNAs in the CRISPR system. Thanks to such insights, we are beginning to get a glimpse of the prokaryotic RNA infrastructure, just as we have done with eukaryotes.
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Affiliation(s)
- Patrick J Biggs
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
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Kortmann J, Sczodrok S, Rinnenthal J, Schwalbe H, Narberhaus F. Translation on demand by a simple RNA-based thermosensor. Nucleic Acids Res 2010; 39:2855-68. [PMID: 21131278 PMCID: PMC3074152 DOI: 10.1093/nar/gkq1252] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Structured RNA regions are important gene control elements in prokaryotes and eukaryotes. Here, we show that the mRNA of a cyanobacterial heat shock gene contains a built-in thermosensor critical for photosynthetic activity under stress conditions. The exceptionally short 5′-untranslated region is comprised of a single hairpin with an internal asymmetric loop. It inhibits translation of the Synechocystis hsp17 transcript at normal growth conditions, permits translation initiation under stress conditions and shuts down Hsp17 production in the recovery phase. Point mutations that stabilized or destabilized the RNA structure deregulated reporter gene expression in vivo and ribosome binding in vitro. Introduction of such point mutations into the Synechocystis genome produced severe phenotypic defects. Reversible formation of the open and closed structure was beneficial for viability, integrity of the photosystem and oxygen evolution. Continuous production of Hsp17 was detrimental when the stress declined indicating that shutting-off heat shock protein production is an important, previously unrecognized function of RNA thermometers. We discovered a simple biosensor that strictly adjusts the cellular level of a molecular chaperone to the physiological need.
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Affiliation(s)
- Jens Kortmann
- Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780 Bochum, Germany
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Abstract
RNA-based pathways that regulate protein expression are much more widespread than previously thought. Regulatory RNAs, including 5' and 3' untranslated regions next to the coding sequence, cis-acting antisense RNAs and trans-acting small non-coding RNAs, are effective regulatory molecules that can influence protein expression and function in response to external cues such as temperature, pH and levels of metabolites. This Review discusses the mechanisms by which these regulatory RNAs, together with accessory proteins such as RNases, control the fate of mRNAs and proteins and how this regulation influences virulence in pathogenic bacteria.
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