1
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Lee HK, Lee YT, Fan L, Wilt HM, Conrad CE, Yu P, Zhang J, Shi G, Ji X, Wang YX, Stagno JR. Crystal structure of Escherichia coli thiamine pyrophosphate-sensing riboswitch in the apo state. Structure 2023; 31:848-859.e3. [PMID: 37253356 PMCID: PMC10335363 DOI: 10.1016/j.str.2023.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/16/2023] [Accepted: 05/03/2023] [Indexed: 06/01/2023]
Abstract
The thiamine pyrophosphate (TPP)-sensing riboswitch is one of the earliest discovered and most widespread riboswitches. Numerous structural studies have been reported for this riboswitch bound with various ligands. However, the ligand-free (apo) structure remains unknown. Here, we report a 3.1 Å resolution crystal structure of Escherichia coli TPP riboswitch in the apo state, which exhibits an extended, Y-shaped conformation further supported by small-angle X-ray scattering data and driven molecular dynamics simulations. The loss of ligand interactions results in helical uncoiling of P5 and disruption of the key tertiary interaction between the sensory domains. Opening of the aptamer propagates to the gene-regulatory P1 helix and generates the key conformational flexibility needed for the switching behavior. Much of the ligand-binding site at the three-way junction is unaltered, thereby maintaining a partially preformed pocket. Together, these results paint a dynamic picture of the ligand-induced conformational changes in TPP riboswitches that confer conditional gene regulation.
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Affiliation(s)
- Hyun Kyung Lee
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Yun-Tzai Lee
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD 21702, USA
| | - Haley M Wilt
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Chelsie E Conrad
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Ping Yu
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Genbin Shi
- Biomolecular Structure Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Xinhua Ji
- Biomolecular Structure Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Yun-Xing Wang
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Jason R Stagno
- Protein-Nucleic Acid Interaction Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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Giarimoglou N, Kouvela A, Maniatis A, Papakyriakou A, Zhang J, Stamatopoulou V, Stathopoulos C. A Riboswitch-Driven Era of New Antibacterials. Antibiotics (Basel) 2022; 11:antibiotics11091243. [PMID: 36140022 PMCID: PMC9495366 DOI: 10.3390/antibiotics11091243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/01/2022] [Accepted: 09/08/2022] [Indexed: 11/26/2022] Open
Abstract
Riboswitches are structured non-coding RNAs found in the 5′ UTR of important genes for bacterial metabolism, virulence and survival. Upon the binding of specific ligands that can vary from simple ions to complex molecules such as nucleotides and tRNAs, riboswitches change their local and global mRNA conformations to affect downstream transcription or translation. Due to their dynamic nature and central regulatory role in bacterial metabolism, riboswitches have been exploited as novel RNA-based targets for the development of new generation antibacterials that can overcome drug-resistance problems. During recent years, several important riboswitch structures from many bacterial representatives, including several prominent human pathogens, have shown that riboswitches are ideal RNA targets for new compounds that can interfere with their structure and function, exhibiting much reduced resistance over time. Most interestingly, mainstream antibiotics that target the ribosome have been shown to effectively modulate the regulatory behavior and capacity of several riboswitches, both in vivo and in vitro, emphasizing the need for more in-depth studies and biological evaluation of new antibiotics. Herein, we summarize the currently known compounds that target several main riboswitches and discuss the role of mainstream antibiotics as modulators of T-box riboswitches, in the dawn of an era of novel inhibitors that target important bacterial regulatory RNAs.
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Alexandros Maniatis
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Athanasios Papakyriakou
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi, 15341 Athens, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | | | - Constantinos Stathopoulos
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
- Correspondence: ; Tel.: +30-2610-997932
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3
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Abstract
Transcription of DNA into RNA is crucial to life, and understanding RNA polymerase (RNAP) function has received considerable attention. In contrast, how the nascent RNA folds into structures that impact transcription itself and regulate gene expression remains poorly understood. Here, we combine single-molecule Förster resonance energy transfer and site-specific fluorescent labelling of transcripts within native complexes to enable real-time cotranscriptional folding studies of a metabolite-sensing riboswitch from Escherichia coli. By monitoring the folding of riboswitches stalled at RNAP pausing sites and during active elongation, we reveal a crucial role for RNAP, which directs RNA folding to allow thiamin pyrophosphate sensing within a precise, transcriptional hotspot. Our approach offers a unique opportunity to unveil cotranscriptional processes in eukaryotic and bacterial systems. Cotranscriptional RNA folding is crucial for the timely control of biological processes, but because of its transient nature, its study has remained challenging. While single-molecule Förster resonance energy transfer (smFRET) is unique to investigate transient RNA structures, its application to cotranscriptional studies has been limited to nonnative systems lacking RNA polymerase (RNAP)–dependent features, which are crucial for gene regulation. Here, we present an approach that enables site-specific labeling and smFRET studies of kilobase-length transcripts within native bacterial complexes. By monitoring Escherichia coli nascent riboswitches, we reveal an inverse relationship between elongation speed and metabolite-sensing efficiency and show that pause sites upstream of the translation start codon delimit a sequence hotspot for metabolite sensing during transcription. Furthermore, we demonstrate a crucial role of the bacterial RNAP actively delaying the formation, within the hotspot sequence, of competing structures precluding metabolite binding. Our approach allows the investigation of cotranscriptional regulatory mechanisms in bacterial and eukaryotic elongation complexes.
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4
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Du C, Wang Y, Gong S. Regulation of the ThiM riboswitch is facilitated by the trapped structure formed during transcription of the wild-type sequence. FEBS Lett 2021; 595:2816-2828. [PMID: 34644399 DOI: 10.1002/1873-3468.14202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 11/09/2022]
Abstract
The ThiM riboswitch from Escherichia coli is a typical mRNA device that modulates downstream gene expression by sensing TPP. The helix-based RNA folding theory is used to investigate its detailed regulatory behaviors in cells. This RNA molecule is transcriptionally trapped in a state with the unstructured SD sequence in the absence of TPP, which induces downstream gene expression. As a key step to turn on gene expression, formation of this trapped state (the genetic ON state) highly depends on the co-transcriptional folding of its wild-type sequence. Instead of stabilities of the genetic ON and OFF states, the transcription rate, pause, and ligand levels are combined to affect the ThiM riboswitch-mediated gene regulation, which is consistent with a kinetic control model.
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Affiliation(s)
- Chengyi Du
- Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization, Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains, Huanggang Normal University, China
| | - Yujie Wang
- Department of Physics and Telecommunication Engineering, Zhoukou Normal University, China
| | - Sha Gong
- Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization, Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains, Huanggang Normal University, China
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5
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Beyene SS, Ling T, Ristevski B, Chen M. A novel riboswitch classification based on imbalanced sequences achieved by machine learning. PLoS Comput Biol 2020; 16:e1007760. [PMID: 32687488 PMCID: PMC7392346 DOI: 10.1371/journal.pcbi.1007760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/30/2020] [Accepted: 05/13/2020] [Indexed: 11/24/2022] Open
Abstract
Riboswitch, a part of regulatory mRNA (50-250nt in length), has two main classes: aptamer and expression platform. One of the main challenges raised during the classification of riboswitch is imbalanced data. That is a circumstance in which the records of a sequences of one group are very small compared to the others. Such circumstances lead classifier to ignore minority group and emphasize on majority ones, which results in a skewed classification. We considered sixteen riboswitch families, to be in accord with recent riboswitch classification work, that contain imbalanced sequences. The sequences were split into training and test set using a newly developed pipeline. From 5460 k-mers (k value 1 to 6) produced, 156 features were calculated based on CfsSubsetEval and BestFirst function found in WEKA 3.8. Statistically tested result was significantly difference between balanced and imbalanced sequences (p < 0.05). Besides, each algorithm also showed a significant difference in sensitivity, specificity, accuracy, and macro F-score when used in both groups (p < 0.05). Several k-mers clustered from heat map were discovered to have biological functions and motifs at the different positions like interior loops, terminal loops and helices. They were validated to have a biological function and some are riboswitch motifs. The analysis has discovered the importance of solving the challenges of majority bias analysis and overfitting. Presented results were generalized evaluation of both balanced and imbalanced models, which implies their ability of classifying, to classify novel riboswitches. The Python source code is available at https://github.com/Seasonsling/riboswitch.
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Affiliation(s)
- Solomon Shiferaw Beyene
- Department of Bioinformatics, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Tianyi Ling
- Department of Bioinformatics, College of Life Sciences, Zhejiang University, Hangzhou, China
- School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Blagoj Ristevski
- Faculty of Information and Communication Technologies, Bitola, St. Kliment Ohridski University Bitola, ul. Partizanska Bitola, Republic of North Macedonia
| | - Ming Chen
- Department of Bioinformatics, College of Life Sciences, Zhejiang University, Hangzhou, China
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6
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Bédard ASV, Hien EDM, Lafontaine DA. Riboswitch regulation mechanisms: RNA, metabolites and regulatory proteins. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194501. [PMID: 32036061 DOI: 10.1016/j.bbagrm.2020.194501] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/05/2020] [Accepted: 02/06/2020] [Indexed: 12/17/2022]
Abstract
Riboswitches are RNA sensors that have been shown to modulate the expression of downstream genes by altering their structure upon metabolite binding. Riboswitches are unique among cellular regulators in that metabolite detection is strictly performed using RNA interactions with the sensed metabolite and in which no regulatory protein is needed to mediate the interaction. However, recent studies have shed light on riboswitch control mechanisms relying on protein regulators to harness metabolite binding for the mediation of gene expression, thereby increasing the range of cellular factors involved in riboswitch regulation. The interaction between riboswitches and proteins adds another level of evolutionary pressure as riboswitches must maintain key residues for metabolite detection, structural switching and protein binding sites. Here, we review regulatory mechanisms involving Escherichia coli riboswitches that have recently been shown to rely on regulatory proteins. We also discuss the implication of such protein-based riboswitch regulatory mechanisms for genetic regulation.
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Affiliation(s)
- Anne-Sophie Vézina Bédard
- Department of biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Elsa D M Hien
- Department of biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Daniel A Lafontaine
- Department of biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada.
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7
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Gong S, Du C, Wang Y. Regulation of the thiamine pyrophosphate (TPP)-sensing riboswitch in NMT1 mRNA from Neurospora crassa. FEBS Lett 2019; 594:625-635. [PMID: 31664711 DOI: 10.1002/1873-3468.13654] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 10/16/2019] [Accepted: 10/22/2019] [Indexed: 01/06/2023]
Abstract
The expression of Neurospora crassa NMT1 involved in thiamine pyrophosphate (TPP) metabolism is regulated at the level of mRNA splicing by a TPP-sensing riboswitch within the precursor NMT1 mRNA. Here, using the systematic helix-based computational method, we investigated the regulation of this riboswitch. We find that the function of the riboswitch does not depend on the transcription process. Whether TPP is present or not, the riboswitch predominately folds into the ON state, while the OFF state aptamer structure does not appear during transcription. Since the transition from the ON state to the aptamer structure is extremely slow, TPP may interact with the RNA before full formation of the aptamer structure, promoting the switch flipping. The potential to fully form helix P0 of the ON state is necessary to restore ligand-dependent gene control by the riboswitch.
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Affiliation(s)
- Sha Gong
- College of Mathematics and Physics, Huanggang Normal University, China
| | - Chengyi Du
- College of Mathematics and Physics, Huanggang Normal University, China
| | - Yanli Wang
- Department of Physics, Wuhan University, China
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8
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Phylogenomic and comparative analysis of the distribution and regulatory patterns of TPP riboswitches in fungi. Sci Rep 2018; 8:5563. [PMID: 29615754 PMCID: PMC5882874 DOI: 10.1038/s41598-018-23900-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 03/20/2018] [Indexed: 01/01/2023] Open
Abstract
Riboswitches are metabolite or ion sensing cis-regulatory elements that regulate the expression of the associated genes involved in biosynthesis or transport of the corresponding metabolite. Among the nearly 40 different classes of riboswitches discovered in bacteria so far, only the TPP riboswitch has also been found in algae, plants, and in fungi where their presence has been experimentally validated in a few instances. We analyzed all the available complete fungal and related genomes and identified TPP riboswitch-based regulation systems in 138 fungi and 15 oomycetes. We find that TPP riboswitches are most abundant in Ascomycota and Basidiomycota where they regulate TPP biosynthesis and/or transporter genes. Many of these transporter genes were found to contain conserved domains consistent with nucleoside, urea and amino acid transporter gene families. The genomic location of TPP riboswitches when correlated with the intron structure of the regulated genes enabled prediction of the precise regulation mechanism employed by each riboswitch. Our comprehensive analysis of TPP riboswitches in fungi provides insights about the phylogenomic distribution, regulatory patterns and functioning mechanisms of TPP riboswitches across diverse fungal species and provides a useful resource that will enhance the understanding of RNA-based gene regulation in eukaryotes.
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9
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Single-molecule FRET studies on the cotranscriptional folding of a thiamine pyrophosphate riboswitch. Proc Natl Acad Sci U S A 2017; 115:331-336. [PMID: 29279370 DOI: 10.1073/pnas.1712983115] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Because RNAs fold as they are being synthesized, their transcription rate can affect their folding. Here, we report the results of single-molecule fluorescence studies that characterize the ligand-dependent cotranscriptional folding of the Escherichia coli thiM riboswitch that regulates translation. We found that the riboswitch aptamer folds into the "off" conformation independent of its ligand, but switches to the "on" conformation during transcriptional pausing near the translational start codon. Ligand binding maintains the riboswitch in the off conformation during transcriptional pauses. We expect our assay will permit the controlled study of the two main physical mechanisms that regulate cotranscriptional folding: transcriptional pausing and transcriptional speed.
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10
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Uhm H, Hohng S. Ligand Recognition Mechanism of Thiamine Pyrophosphate Riboswitch Aptamer. B KOREAN CHEM SOC 2017. [DOI: 10.1002/bkcs.11328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Heesoo Uhm
- Department of Physics and Astronomy; Seoul National University; Seoul 151-747 Korea
- National Center of Creative Research Initiatives; Seoul National University; Seoul 151-747 Korea
| | - Sungchul Hohng
- Department of Physics and Astronomy; Seoul National University; Seoul 151-747 Korea
- National Center of Creative Research Initiatives; Seoul National University; Seoul 151-747 Korea
- Department of Biophysics and Chemical Biology; Seoul National University; Seoul 151-747 Korea
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11
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Gong S, Wang Y, Wang Z, Zhang W. Co-Transcriptional Folding and Regulation Mechanisms of Riboswitches. Molecules 2017; 22:molecules22071169. [PMID: 28703767 PMCID: PMC6152003 DOI: 10.3390/molecules22071169] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 07/07/2017] [Accepted: 07/09/2017] [Indexed: 11/16/2022] Open
Abstract
Riboswitches are genetic control elements within non-coding regions of mRNA. These self-regulatory elements have been found to sense a range of small metabolites, ions, and other physical signals to exert regulatory control of transcription, translation, and splicing. To date, more than a dozen riboswitch classes have been characterized that vary widely in size and secondary structure. Extensive experiments and theoretical studies have made great strides in understanding the general structures, genetic mechanisms, and regulatory activities of individual riboswitches. As the ligand-dependent co-transcriptional folding and unfolding dynamics of riboswitches are the key determinant of gene expression, it is important to investigate the thermodynamics and kinetics of riboswitches both in the presence and absence of metabolites under the transcription. This review will provide a brief summary of the studies about the regulation mechanisms of the pbuE, SMK, yitJ, and metF riboswitches based on the ligand-dependent co-transcriptional folding of the riboswitches.
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Affiliation(s)
- Sha Gong
- Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization, Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains, Huanggang Normal University, Huanggang 438000, Hubei, China.
| | - Yanli Wang
- Department of Physics, Wuhan University, Wuhan 430072, Hubei, China.
| | - Zhen Wang
- Department of Physics, Wuhan University, Wuhan 430072, Hubei, China.
| | - Wenbing Zhang
- Department of Physics, Wuhan University, Wuhan 430072, Hubei, China.
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Bastet L, Chauvier A, Singh N, Lussier A, Lamontagne AM, Prévost K, Massé E, Wade JT, Lafontaine DA. Translational control and Rho-dependent transcription termination are intimately linked in riboswitch regulation. Nucleic Acids Res 2017; 45:7474-7486. [PMID: 28520932 PMCID: PMC5499598 DOI: 10.1093/nar/gkx434] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 05/01/2017] [Accepted: 05/09/2017] [Indexed: 12/21/2022] Open
Abstract
Riboswitches are regulatory elements that control gene expression by altering RNA structure upon the binding of specific metabolites. Although Bacillus subtilis riboswitches have been shown to control premature transcription termination, less is known about regulatory mechanisms employed by Escherichia coli riboswitches, which are predicted to regulate mostly at the level of translation initiation. Here, we present experimental evidence suggesting that the majority of known E. coli riboswitches control transcription termination by using the Rho transcription factor. In the case of the thiamin pyrophosphate-dependent thiM riboswitch, we find that Rho-dependent transcription termination is triggered as a consequence of translation repression. Using in vitro and in vivo assays, we show that the Rho-mediated regulation relies on RNA target elements located at the beginning of thiM coding region. Gene reporter assays indicate that relocating Rho target elements to a different gene induces transcription termination, demonstrating that such elements are modular domains controlling Rho. Our work provides strong evidence that translationally regulating riboswitches also regulate mRNA levels through an indirect control mechanism ensuring tight control of gene expression.
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Affiliation(s)
- Laurène Bastet
- Department of Biology, Faculty of Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Adrien Chauvier
- Department of Biology, Faculty of Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Navjot Singh
- Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Antony Lussier
- Department of Biology, Faculty of Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Anne-Marie Lamontagne
- Department of Biology, Faculty of Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Karine Prévost
- Department of Biochemistry, Faculty of Medicine and Health Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada
| | - Eric Massé
- Department of Biochemistry, Faculty of Medicine and Health Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada
| | - Joseph T. Wade
- Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
- Department of Biomedical Sciences, University at Albany, Albany, NY 12201, USA
| | - Daniel A. Lafontaine
- Department of Biology, Faculty of Sciences, RNA Group, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
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13
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Dependence of Vitamin B1 Metabolism and the State of Astroglia in the Rat Brain on the Supply with this Vitamin. NEUROPHYSIOLOGY+ 2017. [DOI: 10.1007/s11062-017-9607-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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14
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ThiN as a Versatile Domain of Transcriptional Repressors and Catalytic Enzymes of Thiamine Biosynthesis. J Bacteriol 2017; 199:JB.00810-16. [PMID: 28115546 DOI: 10.1128/jb.00810-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/14/2017] [Indexed: 01/21/2023] Open
Abstract
Thiamine biosynthesis is commonly regulated by a riboswitch mechanism; however, the enzymatic steps and regulation of this pathway in archaea are poorly understood. Haloferax volcanii, one of the representative archaea, uses a eukaryote-like Thi4 (thiamine thiazole synthase) for the production of the thiazole ring and condenses this ring with a pyrimidine moiety synthesized by an apparent bacterium-like ThiC (2-methyl-4-amino-5-hydroxymethylpyrimidine [HMP] phosphate synthase) branch. Here we found that archaeal Thi4 and ThiC were encoded by leaderless transcripts, ruling out a riboswitch mechanism. Instead, a novel ThiR transcription factor that harbored an N-terminal helix-turn-helix (HTH) DNA binding domain and C-terminal ThiN (TMP synthase) domain was identified. In the presence of thiamine, ThiR was found to repress the expression of thi4 and thiC by a DNA operator sequence that was conserved across archaeal phyla. Despite having a ThiN domain, ThiR was found to be catalytically inactive in compensating for the loss of ThiE (TMP synthase) function. In contrast, bifunctional ThiDN, in which the ThiN domain is fused to an N-terminal ThiD (HMP/HMP phosphate [HMP-P] kinase) domain, was found to be interchangeable for ThiE function and, thus, active in thiamine biosynthesis. A conserved Met residue of an extended α-helix near the active-site His of the ThiN domain was found to be important for ThiDN catalytic activity, whereas the corresponding Met residue was absent and the α-helix was shorter in ThiR homologs. Thus, we provide new insight into residues that distinguish catalytic from noncatalytic ThiN domains and reveal that thiamine biosynthesis in archaea is regulated by a transcriptional repressor, ThiR, and not by a riboswitch.IMPORTANCE Thiamine pyrophosphate (TPP) is a cofactor needed for the enzymatic activity of many cellular processes, including central metabolism. In archaea, thiamine biosynthesis is an apparent chimera of eukaryote- and bacterium-type pathways that is not well defined at the level of enzymatic steps or regulatory mechanisms. Here we find that ThiN is a versatile domain of transcriptional repressors and catalytic enzymes of thiamine biosynthesis in archaea. Our study provides new insight into residues that distinguish catalytic from noncatalytic ThiN domains and reveals that archaeal thiamine biosynthesis is regulated by a ThiN domain transcriptional repressor, ThiR, and not by a riboswitch.
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15
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Deciphering the mRNP Code: RNA-Bound Determinants of Post-Transcriptional Gene Regulation. Trends Biochem Sci 2017; 42:369-382. [PMID: 28268044 DOI: 10.1016/j.tibs.2017.02.004] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/27/2017] [Accepted: 02/10/2017] [Indexed: 12/16/2022]
Abstract
Eukaryotic cells determine the final protein output of their genetic program not only by controlling transcription but also by regulating the localization, translation and turnover rates of their mRNAs. Ultimately, the fate of any given mRNA is determined by the ensemble of all associated RNA-binding proteins (RBPs), non-coding RNAs and metabolites collectively known as the messenger ribonucleoprotein particle (mRNP). Although many mRNA-associated factors have been identified over the past years, little is known about the composition of individual mRNPs and the cooperation of their constituents. In this review we discuss recent progress that has been made on how this 'mRNP code' is established on individual transcripts and how it is interpreted during gene expression in eukaryotic cells.
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16
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Sahr T, Rusniok C, Impens F, Oliva G, Sismeiro O, Coppée JY, Buchrieser C. The Legionella pneumophila genome evolved to accommodate multiple regulatory mechanisms controlled by the CsrA-system. PLoS Genet 2017; 13:e1006629. [PMID: 28212376 PMCID: PMC5338858 DOI: 10.1371/journal.pgen.1006629] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 03/06/2017] [Accepted: 02/09/2017] [Indexed: 01/09/2023] Open
Abstract
The carbon storage regulator protein CsrA regulates cellular processes post-transcriptionally by binding to target-RNAs altering translation efficiency and/or their stability. Here we identified and analyzed the direct targets of CsrA in the human pathogen Legionella pneumophila. Genome wide transcriptome, proteome and RNA co-immunoprecipitation followed by deep sequencing of a wild type and a csrA mutant strain identified 479 RNAs with potential CsrA interaction sites located in the untranslated and/or coding regions of mRNAs or of known non-coding sRNAs. Further analyses revealed that CsrA exhibits a dual regulatory role in virulence as it affects the expression of the regulators FleQ, LqsR, LetE and RpoS but it also directly regulates the timely expression of over 40 Dot/Icm substrates. CsrA controls its own expression and the stringent response through a regulatory feedback loop as evidenced by its binding to RelA-mRNA and links it to quorum sensing and motility. CsrA is a central player in the carbon, amino acid, fatty acid metabolism and energy transfer and directly affects the biosynthesis of cofactors, vitamins and secondary metabolites. We describe the first L. pneumophila riboswitch, a thiamine pyrophosphate riboswitch whose regulatory impact is fine-tuned by CsrA, and identified a unique regulatory mode of CsrA, the active stabilization of RNA anti-terminator conformations inside a coding sequence preventing Rho-dependent termination of the gap operon through transcriptional polarity effects. This allows L. pneumophila to regulate the pentose phosphate pathway and the glycolysis combined or individually although they share genes in a single operon. Thus the L. pneumophila genome has evolved to acclimate at least five different modes of regulation by CsrA giving it a truly unique position in its life cycle. The RNA binding protein CsrA is the master regulator of the bi-phasic life cycle of Legionella pneumophila governing virulence expression in this intracellular pathogen. Here, we have used deep sequencing of RNA enriched by co-immunoprecipitation with epitope-tagged CsrA to identify CsrA-associated transcripts at the genome level. We found 479 mRNAs or non-coding RNAs to be targets of CsrA. Among those major regulators including FleQ, the regulator of flagella expression, LqsR, the regulator of quorum sensing and RpoS implicated in stress response were identified. The expression of over 40 type IV secreted effector proteins important for intracellular survival and virulence are under the control of CsrA. Combined with transcriptomics, whole shotgun proteomics of a wild type and a CsrA mutant strain and functional analyses of several CsrA-targeted RNAs we identified the first riboswitch in L. pneumophila, a thiamine pyrophosphate riboswitch, and discovered a new mode of regulation by CsrA that allows L. pneumophila to regulate the pentose phosphate pathway and the glycolysis combined or individually although they share genes in a single operon. Our results further underline the indispensable role of CsrA in the life cycle of L. pneumophila and provide new insights into its regulatory roles and mechanisms.
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Affiliation(s)
- Tobias Sahr
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris France
- CNRS UMR 3525, Paris, France
| | - Christophe Rusniok
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris France
- CNRS UMR 3525, Paris, France
| | - Francis Impens
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, Inserm U604, INRA Unité sous-contrat, Paris, France
- VIB-UGent Center for Medical Biotechnology, Ghent University, Ghent, Belgium
| | - Giulia Oliva
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris France
- CNRS UMR 3525, Paris, France
| | - Odile Sismeiro
- Institut Pasteur, Transcriptome and EpiGenome, BioMics, Center for Innovation and Technological Research, Paris, France
| | - Jean-Yves Coppée
- Institut Pasteur, Transcriptome and EpiGenome, BioMics, Center for Innovation and Technological Research, Paris, France
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris France
- CNRS UMR 3525, Paris, France
- * E-mail:
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17
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Shimizu M, Masuo S, Itoh E, Zhou S, Kato M, Takaya N. Thiamine synthesis regulates the fermentation mechanisms in the fungus Aspergillus nidulans. Biosci Biotechnol Biochem 2016; 80:1768-75. [DOI: 10.1080/09168451.2016.1158631] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Abstract
Thiamine pyrophosphate (TPP) is a critical cofactor and its biosynthesis is under the control of TPP availability. Here we disrupted a predicted thiA gene of the fungus Aspergillus nidulans and demonstrated that it is essential for synthesizing cellular thiamine. The thiamine riboswitch is a post-transcriptional mechanism for TPP to repress gene expression and it is located on A. nidulans thiA pre-messenger RNA. The thiA riboswitch was not fully derepressed under thiamine-limited conditions, and fully derepressed under environmental stressors. Upon exposure to hypoxic stress, the fungus accumulated more ThiA and NmtA proteins, and more thiamine than under aerobic conditions. The thiA gene was required for the fungus to upregulate hypoxic branched-chain amino acids and ethanol fermentation that involve enzymes containing TPP. These findings indicate that hypoxia modulates thiA expression through the thiamine riboswitch, and alters cellular fermentation mechanisms by regulating the activity of the TPP enzymes.
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Affiliation(s)
- Motoyuki Shimizu
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
- Faculty of Agriculture, Department of Applied Biological Chemistry, Meijo University, Nagoya, Japan
| | - Shunsuke Masuo
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Eriko Itoh
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Shengmin Zhou
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Masashi Kato
- Faculty of Agriculture, Department of Applied Biological Chemistry, Meijo University, Nagoya, Japan
| | - Naoki Takaya
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
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18
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Landes N, Gasser B, Vorauer-Uhl K, Lhota G, Mattanovich D, Maurer M. The vitamin-sensitive promoter PTHI11enables pre-defined autonomous induction of recombinant protein production inPichia pastoris. Biotechnol Bioeng 2016; 113:2633-2643. [DOI: 10.1002/bit.26041] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/21/2016] [Accepted: 06/23/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Nils Landes
- Department of Biotechnology; BOKU-University of Natural Resources and Life Sciences Vienna; Muthgasse 18 Vienna 1190 Austria
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Vienna Austria
| | - Brigitte Gasser
- Department of Biotechnology; BOKU-University of Natural Resources and Life Sciences Vienna; Muthgasse 18 Vienna 1190 Austria
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Vienna Austria
| | - Karola Vorauer-Uhl
- Department of Biotechnology; BOKU-University of Natural Resources and Life Sciences Vienna; Muthgasse 18 Vienna 1190 Austria
| | - Gabriele Lhota
- Department of Biotechnology; BOKU-University of Natural Resources and Life Sciences Vienna; Muthgasse 18 Vienna 1190 Austria
| | - Diethard Mattanovich
- Department of Biotechnology; BOKU-University of Natural Resources and Life Sciences Vienna; Muthgasse 18 Vienna 1190 Austria
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Vienna Austria
| | - Michael Maurer
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Vienna Austria
- School of Bioengineering; University of Applied Sciences; FH Campus Vienna Austria
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19
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D'Arrigo I, Bojanovič K, Yang X, Holm Rau M, Long KS. Genome-wide mapping of transcription start sites yields novel insights into the primary transcriptome ofPseudomonas putida. Environ Microbiol 2016; 18:3466-3481. [DOI: 10.1111/1462-2920.13326] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/01/2016] [Indexed: 01/09/2023]
Affiliation(s)
- Isotta D'Arrigo
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark; Kogle Allé 6 DK-2970 Hørsholm Denmark
| | - Klara Bojanovič
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark; Kogle Allé 6 DK-2970 Hørsholm Denmark
| | - Xiaochen Yang
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark; Kogle Allé 6 DK-2970 Hørsholm Denmark
| | - Martin Holm Rau
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark; Kogle Allé 6 DK-2970 Hørsholm Denmark
| | - Katherine S. Long
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark; Kogle Allé 6 DK-2970 Hørsholm Denmark
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20
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Vandivier LE, Anderson SJ, Foley SW, Gregory BD. The Conservation and Function of RNA Secondary Structure in Plants. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:463-88. [PMID: 26865341 PMCID: PMC5125251 DOI: 10.1146/annurev-arplant-043015-111754] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
RNA transcripts fold into secondary structures via intricate patterns of base pairing. These secondary structures impart catalytic, ligand binding, and scaffolding functions to a wide array of RNAs, forming a critical node of biological regulation. Among their many functions, RNA structural elements modulate epigenetic marks, alter mRNA stability and translation, regulate alternative splicing, transduce signals, and scaffold large macromolecular complexes. Thus, the study of RNA secondary structure is critical to understanding the function and regulation of RNA transcripts. Here, we review the origins, form, and function of RNA secondary structure, focusing on plants. We then provide an overview of methods for probing secondary structure, from physical methods such as X-ray crystallography and nuclear magnetic resonance (NMR) imaging to chemical and nuclease probing methods. Combining these latter methods with high-throughput sequencing has enabled them to scale across whole transcriptomes, yielding tremendous new insights into the form and function of RNA secondary structure.
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Affiliation(s)
- Lee E Vandivier
- Department of Biology, School of Arts and Sciences, and
- Cell and Molecular Biology Graduate Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104;
| | | | - Shawn W Foley
- Department of Biology, School of Arts and Sciences, and
- Cell and Molecular Biology Graduate Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104;
| | - Brian D Gregory
- Department of Biology, School of Arts and Sciences, and
- Cell and Molecular Biology Graduate Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104;
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21
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Abstract
The biosynthesis of thiamin pyrophosphate (TPP) in prokaryotes, as represented by the Escherichia coli and the Bacillus subtilis pathways, is summarized in this review. The thiazole heterocycle is formed by the convergence of three separate pathways. First, the condensation of glyceraldehyde 3-phosphate and pyruvate, catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (Dxs), gives 1-deoxy-D-xylulose 5-phosphate (DXP). Next, the sulfur carrier protein ThiS-COO- is converted to its carboxyterminal thiocarboxylate in reactions catalyzed by ThiF, ThiI, and NifS (ThiF and IscS in B. subtilis). Finally, tyrosine (glycine in B. subtilis) is converted to dehydroglycine by ThiH (ThiO in B. subtilis). Thiazole synthase (ThiG) catalyzes the complex condensation of ThiS-COSH, dehydroglycine, and DXP to give a thiazole tautomer, which is then aromatized to carboxythiazole phosphate by TenI (B. subtilis). Hydroxymethyl pyrimidine phosphate (HMP-P) is formed by a complicated rearrangement reaction of 5-aminoimidazole ribotide (AIR) catalyzed by ThiC. ThiD then generates hydroxymethyl pyrimidine pyrophosphate. The coupling of the two heterocycles and decarboxylation, catalyzed by thiamin phosphate synthase (ThiE), gives thiamin phosphate. A final phosphorylation, catalyzed by ThiL, completes the biosynthesis of TPP, the biologically active form of the cofactor. This review reviews the current status of mechanistic and structural studies on the enzymes involved in this pathway. The availability of multiple orthologs of the thiamin biosynthetic enzymes has also greatly facilitated structural studies, and most of the thiamin biosynthetic and salvage enzymes have now been structurally characterized.
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22
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Complete Genome Sequence of Mycoplasma hominis Strain Sprott (ATCC 33131), Isolated from a Patient with Nongonococcal Urethritis. GENOME ANNOUNCEMENTS 2015; 3:3/4/e00771-15. [PMID: 26159538 PMCID: PMC4498124 DOI: 10.1128/genomea.00771-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Presented here is the complete and annotated genome sequence of Mycoplasma hominis Sprott (ATCC 33131). The chromosome comprises 695,214 bp, which is approximately 30 kb larger than the syntenic genome of M. hominis PG21(T). Tetracycline resistance of strain Sprott is most probably conferred by the tetM determinant, harbored on a mosaic transposon-like structure.
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23
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Liu Y, Zhang W, Xie L, Liu H, Gong G, Zhu B, Hu Y. Acthi, a thiazole biosynthesis enzyme, is essential for thiamine biosynthesis and CPC production in Acremonium chrysogenum. Microb Cell Fact 2015; 14:50. [PMID: 25886533 PMCID: PMC4416257 DOI: 10.1186/s12934-015-0235-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 03/30/2015] [Indexed: 11/13/2022] Open
Abstract
Background The filamentous fungus Acremonium chrysogenum is an important industrial fungus and is used in the production of the β-lactam antibiotic cephalosporin C. Little is known regarding the molecular and biological mechanisms of how this industrial strain was improved by mutagenesis and molecular breeding. Comparative proteomics is one of the most powerful methods to evaluate the influence of gene expression on metabolite production. Results In this study, we used comparative proteomics to investigate the molecular mechanisms involved in the biosynthesis of cephalosporin C between a high-producer (HY) strain and a wide-type (WT) strain. We found that the expression levels of thiamine biosynthesis-related enzymes, including the thiazole biosynthesis enzyme (Acthi), pyruvate oxidase, flavin adenine dinucleotide (FAD)-dependent oxidoreductase and sulfur carrier protein-thiS, were up-regulated in the HY strain. An Acthi-silencing mutant of the WT strain grew poorly on chemically defined medium (MMC) in the absence of thiamine, and its growth was recovered on MMC medium supplemented with thiamine. The intracellular thiamine content was changed in the Acthi silencing or over-expression mutants. In addition, we demonstrated that the manipulation of the Acthi gene can affect the hyphal growth of Acremonium chrysogenum, the transcription levels of cephalosporin C biosynthetic genes, the quantification levels of precursor amino acids for cephalosporin C synthesis and the expression levels of thiamine diphosphate-dependent enzymes. Over-expression of Acthi can significantly increase the cephalosporin C yield in both the WT strain and the HY mutant strain. Conclusions Using comparative proteomics, four differently expressed proteins were exploited, whose functions may be involved in thiamine diphosphate metabolism. Among these proteins, the thiazole biosynthesis enzyme (ActhiS) may play an important role in cephalosporin C biosynthesis. Our studies suggested that Acthi might be involved in the transcriptional regulation of cephalosporin C biosynthesis. Therefore, the thiamine metabolic pathway could be a potential target for the molecular breeding of this cephalosporin C producer for industrial applications.
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Affiliation(s)
- Yan Liu
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, 1599 Zhangheng Road, Shanghai, 201203, China. .,Shanghai Institute of Pharmaceutical Industry, 1320 Beijing Road (W), Shanghai, 200040, China.
| | - Wei Zhang
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, 1599 Zhangheng Road, Shanghai, 201203, China.
| | - Liping Xie
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, 1599 Zhangheng Road, Shanghai, 201203, China.
| | - Hong Liu
- Shanghai Institute of Pharmaceutical Industry, 1320 Beijing Road (W), Shanghai, 200040, China. .,Present address: Luye Pharma Group Ltd., Yantai, Shandong, 264003, China.
| | - Guihua Gong
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, 1599 Zhangheng Road, Shanghai, 201203, China.
| | - Baoquan Zhu
- Shanghai Institute of Pharmaceutical Industry, 1320 Beijing Road (W), Shanghai, 200040, China.
| | - Youjia Hu
- China State Institute of Pharmaceutical Industry, Zhangjiang Institute, 1599 Zhangheng Road, Shanghai, 201203, China.
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24
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Yadav S, Swati D, Chandrasekharan H. Thiamine Pyrophosphate Riboswitch in Some Representative Plant Species: A Bioinformatics Study. J Comput Biol 2015; 22:1-9. [DOI: 10.1089/cmb.2014.0169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Sunita Yadav
- Department of Bioinformatics, MMV, Banaras Hindu University, Varanasi, India
| | - D. Swati
- Department of Bioinformatics, MMV, Banaras Hindu University, Varanasi, India
- Department of Physics, MMV, Banaras Hindu University, Varanasi, India
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25
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Havill JT, Bhatiya C, Johnson SM, Sheets JD, Thompson JS. A new approach for detecting riboswitches in DNA sequences. ACTA ACUST UNITED AC 2014; 30:3012-9. [PMID: 25015992 DOI: 10.1093/bioinformatics/btu479] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
MOTIVATION Riboswitches are short sequences of messenger RNA that can change their structural conformation to regulate the expression of adjacent genes. Computational prediction of putative riboswitches can provide direction to molecular biologists studying riboswitch-mediated gene expression. RESULTS The Denison Riboswitch Detector (DRD) is a new computational tool with a Web interface that can quickly identify putative riboswitches in DNA sequences on the scale of bacterial genomes. Riboswitch descriptions are easily modifiable and new ones are easily created. The underlying algorithm converts the problem to a 'heaviest path' problem on a multipartite graph, which is then solved using efficient dynamic programming. We show that DRD can achieve ∼ 88-99% sensitivity and >99.99% specificity on 13 riboswitch families. AVAILABILITY AND IMPLEMENTATION DRD is available at http://drd.denison.edu.
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Affiliation(s)
- Jessen T Havill
- Department of Mathematics and Computer Science, Department of Biology, Denison University, Granville, OH 43023, Capco, New York, NY, 10005, Department of Computer Science, Wake Forest University, Winston-Salem, NC 27109 and College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Chinmoy Bhatiya
- Department of Mathematics and Computer Science, Department of Biology, Denison University, Granville, OH 43023, Capco, New York, NY, 10005, Department of Computer Science, Wake Forest University, Winston-Salem, NC 27109 and College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Steven M Johnson
- Department of Mathematics and Computer Science, Department of Biology, Denison University, Granville, OH 43023, Capco, New York, NY, 10005, Department of Computer Science, Wake Forest University, Winston-Salem, NC 27109 and College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Joseph D Sheets
- Department of Mathematics and Computer Science, Department of Biology, Denison University, Granville, OH 43023, Capco, New York, NY, 10005, Department of Computer Science, Wake Forest University, Winston-Salem, NC 27109 and College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Jeffrey S Thompson
- Department of Mathematics and Computer Science, Department of Biology, Denison University, Granville, OH 43023, Capco, New York, NY, 10005, Department of Computer Science, Wake Forest University, Winston-Salem, NC 27109 and College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
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26
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Chang AL, McKeague M, Liang JC, Smolke CD. Kinetic and equilibrium binding characterization of aptamers to small molecules using a label-free, sensitive, and scalable platform. Anal Chem 2014; 86:3273-8. [PMID: 24548121 PMCID: PMC3983011 DOI: 10.1021/ac5001527] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
![]()
Nucleic
acid aptamers function as versatile sensing and targeting
agents for analytical, diagnostic, therapeutic, and gene-regulatory
applications, but their limited characterization and functional validation
have hindered their broader implementation. We report the development
of a surface plasmon resonance-based platform for rapid characterization
of kinetic and equilibrium binding properties of aptamers to small
molecules. Our system is label-free and scalable and enables analysis
of different aptamer–target pairs and binding conditions with
the same platform. This method demonstrates improved sensitivity,
flexibility, and stability compared to other aptamer characterization
methods. We validated our assay against previously reported aptamer
affinity and kinetic measurements and further characterized a diverse
panel of 12 small molecule-binding RNA and DNA aptamers. We report
the first kinetic characterization for six of these aptamers and affinity
characterization of two others. This work is the first example of
direct comparison of in vitro selected and natural aptamers using
consistent characterization conditions, thus providing insight into
the influence of environmental conditions on aptamer binding kinetics
and affinities, indicating different possible regulatory strategies
used by natural aptamers, and identifying potential in vitro selection
strategies to improve resulting binding affinities.
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Affiliation(s)
- Andrew L Chang
- Department of Chemistry, Stanford University , Stanford, CA 94305, United States
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27
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Appasamy SD, Ramlan EI, Firdaus-Raih M. Comparative sequence and structure analysis reveals the conservation and diversity of nucleotide positions and their associated tertiary interactions in the riboswitches. PLoS One 2013; 8:e73984. [PMID: 24040136 PMCID: PMC3764141 DOI: 10.1371/journal.pone.0073984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 07/25/2013] [Indexed: 12/17/2022] Open
Abstract
The tertiary motifs in complex RNA molecules play vital roles to either stabilize the formation of RNA 3D structure or to provide important biological functionality to the molecule. In order to better understand the roles of these tertiary motifs in riboswitches, we examined 11 representative riboswitch PDB structures for potential agreement of both motif occurrences and conservations. A total of 61 unique tertiary interactions were found in the reference structures. In addition to the expected common A-minor motifs and base-triples mainly involved in linking distant regions the riboswitch structures three highly conserved variants of A-minor interactions called G-minors were found in the SAM-I and FMN riboswitches where they appear to be involved in the recognition of the respective ligand’s functional groups. From our structural survey as well as corresponding structure and sequence alignments, the agreement between motif occurrences and conservations are very prominent across the representative riboswitches. Our analysis provide evidence that some of these tertiary interactions are essential components to form the structure where their sequence positions are conserved despite a high degree of diversity in other parts of the respective riboswitches sequences. This is indicative of a vital role for these tertiary interactions in determining the specific biological function of riboswitch.
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Affiliation(s)
- Sri D Appasamy
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor, Malaysia
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28
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Lünse CE, Schüller A, Mayer G. The promise of riboswitches as potential antibacterial drug targets. Int J Med Microbiol 2013; 304:79-92. [PMID: 24140145 DOI: 10.1016/j.ijmm.2013.09.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Riboswitches represent promising novel RNA structures for developing compounds that artificially regulate gene expression and, thus, bacterial growth. The past years have seen increasing efforts to identify metabolite-analogues which act on riboswitches and which reveal antibacterial activity. Here, we summarize the current inventory of riboswitch-targeting compounds, their characteristics and antibacterial potential.
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Affiliation(s)
- Christina E Lünse
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Anna Schüller
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Günter Mayer
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany.
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Siddaramappa S, Challacombe JF, Petersen JM, Pillai S, Kuske CR. Genetic diversity within the genus Francisella as revealed by comparative analyses of the genomes of two North American isolates from environmental sources. BMC Genomics 2012; 13:422. [PMID: 22920915 PMCID: PMC3479022 DOI: 10.1186/1471-2164-13-422] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 08/14/2012] [Indexed: 12/14/2022] Open
Abstract
Background Francisella tularensis is an intracellular pathogen that causes tularemia in humans and the public health importance of this bacterium has been well documented in recent history. Francisella philomiragia, a distant relative of F. tularensis, is thought to constitute an environmental lineage along with Francisella novicida. Nevertheless, both F. philomiragia and F. novicida have been associated with human disease, primarily in immune-compromised individuals. To understand the genetic relationships and evolutionary contexts among different lineages within the genus Francisella, the genome of Francisella spp. strain TX07-7308 was sequenced and compared to the genomes of F. philomiragia strains ATCC 25017 and 25015, F. novicida strain U112, and F. tularensis strain Schu S4. Results The size of strain ATCC 25017 chromosome was 2,045,775 bp and contained 1,983 protein-coding genes. The size of strain TX07-7308 chromosome was 2,035,931 bp and contained 1,980 protein-coding genes. Pairwise BLAST comparisons indicated that strains TX07-7308 and ATCC 25017 contained 1,700 protein coding genes in common. NUCmer analyses revealed that the chromosomes of strains TX07-7308 and ATCC 25017 were mostly collinear except for a few gaps, translocations, and/or inversions. Using the genome sequence data and comparative analyses with other members of the genus Francisella (e.g., F. novicida strain U112 and F. tularensis strain Schu S4), several strain-specific genes were identified. Strains TX07-7308 and ATCC 25017 contained an operon with six open reading frames encoding proteins related to enzymes involved in thiamine biosynthesis that was absent in F. novicida strain U112 and F. tularensis strain Schu S4. Strain ATCC 25017 contained an operon putatively involved in lactose metabolism that was absent in strain TX07-7308, F. novicida strain U112, and F. tularensis strain Schu S4. In contrast, strain TX07-7308 contained an operon putatively involved in glucuronate metabolism that was absent in the genomes of strain ATCC 25017, F. novicida strain U112, and F. tularensis strain Schu S4. The polymorphic nature of polysaccharide biosynthesis/modification gene clusters among different Francisella strains was also evident from genome analyses. Conclusions From genome comparisons, it appeared that genes encoding novel functions have contributed to the metabolic enrichment of the environmental lineages within the genus Francisella. The inability to acquire new genes coupled with the loss of ancestral traits and the consequent reductive evolution may be a cause for, as well as an effect of, niche selection of F. tularensis. Sequencing and comparison of the genomes of more isolates are required to obtain further insights into the ecology and evolution of different species within the genus Francisella.
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Eschbach SH, St-Pierre P, Penedo JC, Lafontaine DA. Folding of the SAM-I riboswitch: a tale with a twist. RNA Biol 2012; 9:535-41. [PMID: 22336759 DOI: 10.4161/rna.19648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Riboswitches are ligand-dependent RNA genetic regulators that control gene expression by altering their structures. The elucidation of riboswitch conformational changes before and after ligand recognition is crucial to understand how riboswitches can achieve high ligand binding affinity and discrimination against cellular analogs. The detailed characterization of riboswitch folding pathways suggest that they may use their intrinsic conformational dynamics to sample a large array of structures, some of which being nearly identical to ligand-bound molecules. Some of these structural conformers can be "captured" upon ligand binding, which is crucial for the outcome of gene regulation. Recent studies about the SAM-I riboswitch have revealed unexpected and previously unknown RNA folding mechanisms. For instance, the observed helical twist of the P1 stem upon ligand binding to the SAM-I aptamer adds a new element in the repertoire of RNA strategies for recognition of small metabolites. From an RNA folding perspective, these findings also strongly indicate that the SAM-I riboswitch could achieve ligand recognition by using an optimized combination of conformational capture and induced-fit approaches, a feature that may be shared by other RNA regulatory sequences.
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Affiliation(s)
- Sébastien H Eschbach
- Groupe ARN/RNA Group, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
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31
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Folding energy landscape of the thiamine pyrophosphate riboswitch aptamer. Proc Natl Acad Sci U S A 2012; 109:1485-9. [PMID: 22219369 DOI: 10.1073/pnas.1115045109] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Riboswitches are motifs in the untranslated regions (UTRs) of RNA transcripts that sense metabolite levels and modulate the expression of the corresponding genes for metabolite import, export, synthesis, or degradation. All riboswitches contain an aptamer: an RNA structure that, upon binding ligand, folds to expose or sequester regulatory elements in the adjacent sequence through alternative nucleotide pairing. The coupling between ligand binding and aptamer folding is central to the regulatory mechanisms of thiamine pyrophosphate (TPP) riboswitches and has not been fully characterized. Here, we show that TPP aptamer folding can be decomposed into ligand-independent and -dependent steps that correspond to the formation of secondary and tertiary structures, respectively. We reconstructed the full energy landscape for folding of the wild-type (WT) aptamer and measured perturbations of this landscape arising from mutations or ligand binding. We show that TPP binding proceeds in two steps, from a weakly to a strongly bound state. Our data imply a hierarchical folding sequence, and provide a framework for understanding molecular mechanism throughout the TPP riboswitch family.
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32
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Dunn IS. RNA templating of molecular assembly and covalent modification patterning in early molecular evolution and modern biosystems. J Theor Biol 2011; 284:32-41. [PMID: 21703277 DOI: 10.1016/j.jtbi.2011.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 05/23/2011] [Accepted: 06/08/2011] [Indexed: 10/18/2022]
Abstract
The Direct RNA Template (DRT) hypothesis proposes that an early stage of genetic code evolution involved RNA molecules acting as stereochemical recognition templates for assembly of specific amino acids in sequence-ordered arrays, providing a framework for directed covalent peptide bond formation. It is hypothesized here that modern biological precedents may exist for RNA-based structural templating with functional analogies to hypothetical DRT systems. Beyond covalent molecular assembly, an extension of the DRT concept can include RNA molecules acting as dynamic structural template guides for the specific non-covalent assembly of multi-subunit complexes, equivalent to structural assembly chaperones. However, despite numerous precedents for RNA molecules acting as scaffolds for protein complexes, true RNA-mediated assembly chaperoning appears to be absent in modern biosystems. Another level of function with parallels to a DRT system is possible if RNA structural motifs dynamically guided specific patterns of catalytic modifications within multiple target sites in a pre-formed polymer or macromolecular complex. It is suggested that this type of structural RNA templating could logically play a functional role in certain areas of biology, one of which is the glycome of complex organisms. If any such RNA templating processes are shown to exist, they would share no necessary evolutionary relationships with events during early molecular evolution, but may promote understanding of the practical limits of biological RNA functions now and in the ancient RNA World. Awareness of these formal possibilities may also assist in the current search for functions of extensive non-coding RNAs in complex organisms, or for efforts towards artificial rendering of DRT systems.
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Affiliation(s)
- Ian S Dunn
- CytoCure LLC, 100 Cummings Center, Beverly, MA 01915, USA.
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Common ancestry and novel genetic traits of Francisella novicida-like isolates from North America and Australia as revealed by comparative genomic analyses. Appl Environ Microbiol 2011; 77:5110-22. [PMID: 21666011 DOI: 10.1128/aem.00337-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Francisella novicida is a close relative of Francisella tularensis, the causative agent of tularemia. The genomes of F. novicida-like clinical isolates 3523 (Australian strain) and Fx1 (Texas strain) were sequenced and compared to F. novicida strain U112 and F. tularensis strain Schu S4. The strain 3523 chromosome is 1,945,310 bp and contains 1,854 protein-coding genes. The strain Fx1 chromosome is 1,913,619 bp and contains 1,819 protein-coding genes. NUCmer analyses revealed that the genomes of strains Fx1 and U112 are mostly colinear, whereas the genome of strain 3523 has gaps, translocations, and/or inversions compared to genomes of strains Fx1 and U112. Using the genome sequence data and comparative analyses with other members of the genus Francisella, several strain-specific genes that encode putative proteins involved in RTX toxin production, polysaccharide biosynthesis/modification, thiamine biosynthesis, glucuronate utilization, and polyamine biosynthesis were identified. The RTX toxin synthesis and secretion operon of strain 3523 contains four open reading frames (ORFs) and was named rtxCABD. Based on the alignment of conserved sequences upstream of operons involved in thiamine biosynthesis from various bacteria, a putative THI box was identified in strain 3523. The glucuronate catabolism loci of strains 3523 and Fx1 contain a cluster of nine ORFs oriented in the same direction that appear to constitute an operon. Strains U112 and Schu S4 appeared to have lost the loci for RTX toxin production, thiamine biosynthesis, and glucuronate utilization as a consequence of host adaptation and reductive evolution. In conclusion, comparative analyses provided insights into the common ancestry and novel genetic traits of these strains.
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The riboswitch regulates a thiamine pyrophosphate ABC transporter of the oral spirochete Treponema denticola. J Bacteriol 2011; 193:3912-22. [PMID: 21622748 DOI: 10.1128/jb.00386-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Thiamine pyrophosphate (TPP), a biologically active form of thiamine (vitamin B₁), is an essential cofactor in all living systems. Microorganisms either synthesize TPP via de novo biosynthesis pathways or uptake exogenous thiamine from the environment via specific transporters. The oral spirochete Treponema denticola is an important pathogen that is associated with human periodontal diseases. It lacks a de novo TPP biosynthesis pathway and needs exogenous TPP for growth, suggesting that it may obtain exogenous TPP via a thiamine transporter. In this study, we identified a gene cluster that encodes a TPP ABC transporter which consists of a TPP-binding protein (TDE0143), a transmembrane permease (TDE0144), and a cytosolic ATPase (TDE0145). Transcriptional and translational analyses showed that the genes encoding these three proteins are cotranscribed and form an operon (tbpABC(Td)) that is initiated by a σ⁷⁰-like promoter. The expression level of this operon is negatively regulated by exogenous TPP and is mediated by a TPP-sensing riboswitch (Td(thi-)(box)). Genetic and biochemical studies revealed that the TDE0143 deletion mutant (T. denticola ΔtbpA) had a decreased ability to transport exogenous TPP, and the mutant failed to grow when exogenous TPP was insufficient. These results taken together indicate that the tbpABC(Td) operon encodes an ABC transporter that is required for the uptake of exogenous TPP and that the expression of this operon is regulated by a TPP-binding riboswitch via a feedback inhibition mechanism.
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35
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Furniss S, Grover N. Thermodynamic examination of the pyrophosphate sensor helix in the thiamine pyrophosphate riboswitch. RNA (NEW YORK, N.Y.) 2011; 17:710-717. [PMID: 21367973 PMCID: PMC3062181 DOI: 10.1261/rna.2263211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 01/17/2011] [Indexed: 05/30/2023]
Abstract
Riboswitches are functional mRNA that control gene expression. Thiamine pyrophosphate (TPP) binds to thi-box riboswitch RNA and allosterically inhibits genes that code for proteins involved in the biosynthesis and transport of thiamine. Thiamine binding to the pyrimidine sensor helix and pyrophosphate binding to the pyrophosphate sensor helix cause changes in RNA conformation that regulate gene expression. Here we examine the thermodynamic properties of the internal loop of the pyrophosphate binding domain by comparing the wild-type construct (RNA WT) with six modified 2 x 2 bulged RNA and one 2 x 2 bulged DNA. The wild-type construct retains five conserved bases of the pyrophosphate sensor domain, two of which are in the 2 x 2 bulge (C65 and G66). The RNA WT construct was among the most stable (ΔG°₃₇ = -7.7 kcal/mol) in 1 M KCl at pH 7.5. Breaking the A•G mismatch of the bulge decreases the stability of the construct ~0.5-1 kcal/mol, but does not affect magnesium binding to the RNA WT. Guanine at position 48 is important for RNA-Mg²+ interactions of the TPP-binding riboswitch at pH 7.5. In the presence of 9.5 mM magnesium at pH 5.5, the bulged RNA constructs gained an average of 1.1 kcal/mol relative to 1 M salt. Formation of a single A+•C mismatch base pair contributes about 0.5 kcal/mol at pH 5.5, whereas two tandem A+•C mismatch base pairs together contribute about 2 kcal/mol.
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Affiliation(s)
- Stephanie Furniss
- Department of Chemistry and Biochemistry, the Colorado College, Colorado Springs, Colorado 80903, USA
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36
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Lau PS, Coombes BK, Li Y. A general approach to the construction of structure-switching reporters from RNA aptamers. Angew Chem Int Ed Engl 2011; 49:7938-42. [PMID: 20845339 DOI: 10.1002/anie.201002621] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Pui Sai Lau
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main St. W., Hamilton, ON L8N 3Z5, Canada
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37
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Wilson RC, Smith AM, Fuchs RT, Kleckner IR, Henkin TM, Foster MP. Tuning riboswitch regulation through conformational selection. J Mol Biol 2011; 405:926-38. [PMID: 21075119 PMCID: PMC3019289 DOI: 10.1016/j.jmb.2010.10.056] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/27/2010] [Accepted: 10/28/2010] [Indexed: 01/20/2023]
Abstract
The S(MK) box riboswitch, which represents one of three known classes of S-adenosylmethionine (SAM)-responsive riboswitches, regulates gene expression in bacteria at the level of translation initiation. In contrast to most riboswitches, which contain separate domains responsible for ligand recognition and gene regulation, the ligand-binding and regulatory domains of the S(MK) box riboswitch are coincident. This property was exploited to allow the first atomic-level characterization of a functionally intact riboswitch in both the ligand-bound state and the ligand-free state. NMR spectroscopy revealed distinct mutually exclusive RNA conformations that are differentially populated in the presence or in the absence of the effector metabolite. Isothermal titration calorimetry and in vivo reporter assay results revealed the thermodynamic and functional consequences of this conformational equilibrium. We present a comprehensive model of the structural, thermodynamic, and functional properties of this compact RNA regulatory element.
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Affiliation(s)
- Ross C. Wilson
- Department of Biochemistry, Ohio State University, Columbus, OH 43210
- Center for RNA Biology, Ohio State University, Columbus, OH 43210
| | - Angela M. Smith
- Center for RNA Biology, Ohio State University, Columbus, OH 43210
- Department of Microbiology, Ohio State University, Columbus, OH 43210
| | - Ryan T. Fuchs
- Center for RNA Biology, Ohio State University, Columbus, OH 43210
- Department of Microbiology, Ohio State University, Columbus, OH 43210
| | - Ian R. Kleckner
- Department of Biochemistry, Ohio State University, Columbus, OH 43210
- Center for RNA Biology, Ohio State University, Columbus, OH 43210
| | - Tina M. Henkin
- Center for RNA Biology, Ohio State University, Columbus, OH 43210
- Department of Microbiology, Ohio State University, Columbus, OH 43210
| | - Mark P. Foster
- Department of Biochemistry, Ohio State University, Columbus, OH 43210
- Center for RNA Biology, Ohio State University, Columbus, OH 43210
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38
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Lau PS, Coombes BK, Li Y. A General Approach to the Construction of Structure-Switching Reporters from RNA Aptamers. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201002621] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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39
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Grüning NM, Lehrach H, Ralser M. Regulatory crosstalk of the metabolic network. Trends Biochem Sci 2010; 35:220-7. [PMID: 20060301 DOI: 10.1016/j.tibs.2009.12.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 11/23/2009] [Accepted: 12/03/2009] [Indexed: 02/04/2023]
Abstract
The metabolic network has a modular architecture, is robust to perturbations, and responds to biological stimuli and environmental conditions. Through monitoring by metabolite responsive macromolecules, metabolic pathways interact with the transcriptome and proteome. Whereas pathway interconnecting cofactors and substrates report on the overall state of the network, specialised intermediates measure the activity of individual functional units. Transitions in the network affect many of these regulatory metabolites, facilitating the parallel regulation of the timing and control of diverse biological processes. The metabolic network controls its own balance, chromatin structure and the biosynthesis of molecular cofactors; moreover, metabolic shifts are crucial in the response to oxidative stress and play a regulatory role in cancer.
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Affiliation(s)
- Nana-Maria Grüning
- Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
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40
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Kulshina N, Edwards TE, Ferré-D'Amaré AR. Thermodynamic analysis of ligand binding and ligand binding-induced tertiary structure formation by the thiamine pyrophosphate riboswitch. RNA (NEW YORK, N.Y.) 2010; 16:186-96. [PMID: 19948769 PMCID: PMC2802028 DOI: 10.1261/rna.1847310] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 10/05/2009] [Indexed: 05/24/2023]
Abstract
The thi-box riboswitch regulates gene expression in response to the intracellular concentration of thiamine pyrophosphate (TPP) in archaea, bacteria, and eukarya. To complement previous biochemical, genetic, and structural studies of this phylogenetically widespread RNA domain, we have characterized its interaction with TPP by isothermal titration calorimetry. This shows that TPP binding is highly dependent on Mg(2+) concentration. The dissociation constant decreases from approximately 200 nM at 0.5 mM Mg(2+) concentration to approximately 9 nM at 2.5 mM Mg(2+) concentration. Binding is enthalpically driven, but the unfavorable entropy of binding decreases as Mg(2+) concentration rises, suggesting that divalent cations serve to pre-organize the RNA. Mutagenesis, biochemical analysis, and a new crystal structure of the riboswitch suggest that a critical element that participates in organizing the riboswitch structure is the tertiary interaction formed between the P3 and L5 regions. This tertiary contact is distant from the TPP binding site, but calorimetric analysis reveals that even subtle mutations in L5 can have readily detectable effects on TPP binding. The thermodynamic signatures of these mutations, namely decreased favorable enthalpy of binding and small effects on entropy of binding, are consistent with the P3-L5 association contributing allosterically to TPP-induced compaction of the RNA.
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MESH Headings
- Aptamers, Nucleotide/chemistry
- Aptamers, Nucleotide/genetics
- Aptamers, Nucleotide/metabolism
- Base Sequence
- Binding Sites/genetics
- Crystallography, X-Ray
- Escherichia coli/genetics
- Ligands
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- Sequence Analysis, RNA
- Thermodynamics
- Thiamine Pyrophosphate/chemistry
- Thiamine Pyrophosphate/metabolism
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Affiliation(s)
- Nadia Kulshina
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington 98195, USA
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41
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Villa A, Wöhnert J, Stock G. Molecular dynamics simulation study of the binding of purine bases to the aptamer domain of the guanine sensing riboswitch. Nucleic Acids Res 2009; 37:4774-86. [PMID: 19515936 PMCID: PMC2724292 DOI: 10.1093/nar/gkp486] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Riboswitches are a novel class of genetic control elements that function through the direct interaction of small metabolite molecules with structured RNA elements. The ligand is bound with high specificity and affinity to its RNA target and induces conformational changes of the RNA's secondary and tertiary structure upon binding. To elucidate the molecular basis of the remarkable ligand selectivity and affinity of one of these riboswitches, extensive all-atom molecular dynamics simulations in explicit solvent (approximately 1 micros total simulation length) of the aptamer domain of the guanine sensing riboswitch are performed. The conformational dynamics is studied when the system is bound to its cognate ligand guanine as well as bound to the non-cognate ligand adenine and in its free form. The simulations indicate that residue U51 in the aptamer domain functions as a general docking platform for purine bases, whereas the interactions between C74 and the ligand are crucial for ligand selectivity. These findings either suggest a two-step ligand recognition process, including a general purine binding step and a subsequent selection of the cognate ligand, or hint at different initial interactions of cognate and noncognate ligands with residues of the ligand binding pocket. To explore possible pathways of complex dissociation, various nonequilibrium simulations are performed which account for the first steps of ligand unbinding. The results delineate the minimal set of conformational changes needed for ligand release, suggest two possible pathways for the dissociation reaction, and underline the importance of long-range tertiary contacts for locking the ligand in the complex.
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Affiliation(s)
- Alessandra Villa
- Institute of Physical and Theoretical Chemistry and Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
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42
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Wieland M, Benz A, Klauser B, Hartig JS. Artificial ribozyme switches containing natural riboswitch aptamer domains. Angew Chem Int Ed Engl 2009; 48:2715-8. [PMID: 19156802 DOI: 10.1002/anie.200805311] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
RNA Lego: The use of natural riboswitch aptamers in synthetic RNA switches (see picture) should broaden the scope of artificial RNA regulators dramatically. It is shown that thiamine pyrophosphate (TPP) aptamers can be used in engineered devices as very sensitive switches of gene expression in unmodified organisms. The approach demonstrates that intrinsic metabolites can be utilized as external effectors of cellular functions.
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Affiliation(s)
- Markus Wieland
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
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43
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Wieland M, Benz A, Klauser B, Hartig J. Artificial Ribozyme Switches Containing Natural Riboswitch Aptamer Domains. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200805311] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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44
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Abstract
Riboswitches are non-coding RNA elements mainly located in the 5' untranslated regions (UTR) of bacterial genes. They bind to small metabolites and upon binding conformational changes occur that trigger the expression of a certain gene. Riboswitches have been identified that bind to amino acids, purines, and other small metabolites such as thiamine pyrophosphate. Riboswitches contain an aptamer domain which is necessary for interaction with the metabolite and a related expression domain which harbours structural and sequence information required for interference with gene expression. The binding of a metabolite to the aptamer domain induces structural rearrangements that are relayed to the expression domain, thereby interfering with gene expression. To investigate and determine domains of the riboswitches which undergo conformational changes upon metabolite binding we used a dynamic SELEX process and identified RNA aptamers that bind to the metabolite-free variant of the riboswitch but are released upon metabolite addition. By this means, and after determination of the binding region, domains which are necessary for proper function of a full-length riboswitch can be identified.
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Affiliation(s)
- Günter Mayer
- Rheinische Friedrich-Wilhelms-Universität Bonn Life and Medical Sciences Institute, Gerhard-Domagk-Str.1, 53121, Bonn, Germany
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45
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Abstract
Thiamin is synthesized by most prokaryotes and by eukaryotes such as yeast and plants. In all cases, the thiazole and pyrimidine moieties are synthesized in separate branches of the pathway and coupled to form thiamin phosphate. A final phosphorylation gives thiamin pyrophosphate, the active form of the cofactor. Over the past decade or so, biochemical and structural studies have elucidated most of the details of the thiamin biosynthetic pathway in bacteria. Formation of the thiazole requires six gene products, and formation of the pyrimidine requires two. In contrast, details of the thiamin biosynthetic pathway in yeast are only just beginning to emerge. Only one gene product is required for the biosynthesis of the thiazole and one for the biosynthesis of the pyrimidine. Thiamin can also be transported into the cell and can be salvaged through several routes. In addition, two thiamin degrading enzymes have been characterized, one of which is linked to a novel salvage pathway.
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Affiliation(s)
- Christopher T. Jurgenson
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520;
| | - Tadhg P. Begley
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853; ,
| | - Steven E. Ealick
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853; ,
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46
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Bocobza SE, Aharoni A. Switching the light on plant riboswitches. TRENDS IN PLANT SCIENCE 2008; 13:526-33. [PMID: 18778966 DOI: 10.1016/j.tplants.2008.07.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/10/2008] [Accepted: 07/17/2008] [Indexed: 05/21/2023]
Abstract
Riboswitches are natural RNA sensors that affect post-transcriptional processes via their capacity to bind small molecules. To date, these mRNA structures have been shown to regulate the biosynthesis of essential metabolites, including vitamins and amino acids. Although bacterial riboswitches are widespread and characterized, only a single eukaryotic, thiamin-pyrophosphate-binding riboswitch has recently been discovered to direct gene expression by regulating mRNA splicing in fungi, green algae and land plants. It is unclear how widespread riboswitches are and what additional roles they have in eukaryotes. When engineered in plants, riboswitches can function autonomously to modulate gene expression. These discoveries not only trigger novel findings regarding RNA switches in plants, but also spur the exploitation of riboswitches for monitoring metabolite concentrations in planta.
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Affiliation(s)
- Samuel E Bocobza
- Department of Plant Sciences, Weizmann Institute of Science, PO Box 26, Rehovot 76100, Israel
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47
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Abstract
Riboswitches are RNAs capable of binding cellular metabolites using a diverse array of secondary and tertiary structures to modulate gene expression. The recent determination of the three-dimensional structures of parts of six different riboswitches illuminates common features that allow riboswitches to be grouped into one of two types. Type I riboswitches, as exemplified by the purine riboswitch, are characterized by a single, localized binding pocket supported by a largely pre-established global fold. This arrangement limits ligand-induced conformational changes in the RNA to a small region. In contrast, Type II riboswitches, such as the thiamine pyrophosphate riboswitch, contain binding pockets split into at least two spatially distinct sites. As a result, binding induces both local changes to the binding pocket and global architecture. Similar organizational themes are found in other noncoding RNAs, making it possible to begin to build a hierarchical classification of RNA structure based on the spatial organization of their active sites and associated secondary structural elements.
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Affiliation(s)
- Rebecca K Montange
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA
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48
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Rentmeister A, Mayer G, Kuhn N, Famulok M. Secondary structures and functional requirements for thiM riboswitches from Desulfovibrio vulgaris, Erwinia carotovora and Rhodobacter spheroides. Biol Chem 2008; 389:127-34. [PMID: 18163882 DOI: 10.1515/bc.2008.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Abstract Bacterial thiM riboswitches contain aptamer domains that bind the metabolite thiamine pyrophosphate (TPP). Binding of TPP to the aptamer domain induces structural rearrangements that are relayed to the expression domain, thereby interfering with gene expression. Here, we report identification of three putative thiM riboswitches from different bacteria and analysis of their secondary structures. Chemical probing revealed that the riboswitches share similar secondary structures in their aptamer domains that can communicate with the highly variant expression domains in a mechanism likely involving sequestration of the Shine-Dalgarno sequence. Remarkably, the aptamer domain of the thiM gene of Desulfovibrio vulgaris binds TPP with similar affinity and selectivity as that of Escherichia coli, although nucleotides previously shown to form direct contacts to the metabolite are mutated. We also designed small RNA hairpins for each riboswitch that bind the RNA only in the absence of the metabolite. Our study shows that aptamer domains in riboswitches with high similarity in their secondary structures can communicate with a broad variety of non-related expression domains by similar mechanisms.
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Affiliation(s)
- Andrea Rentmeister
- LIMES-Institute, Program Unit Chemical Biology and Medicinal Chemistry, c/o Kekulé-Institute for Organic Chemistry and Biochemistry of the University of Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany
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49
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Ontiveros-Palacios N, Smith AM, Grundy FJ, Soberon M, Henkin TM, Miranda-Ríos J. Molecular basis of gene regulation by the THI-box riboswitch. Mol Microbiol 2007; 67:793-803. [PMID: 18179415 DOI: 10.1111/j.1365-2958.2007.06088.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Riboswitches are genetic control elements located mainly within the 5' untranslated regions of messenger RNAs. These RNA elements undergo conformational changes that modulate gene expression upon binding of regulatory signals including vitamins, amino acids, nucleobases and uncharged tRNA. The thiamin pyrophosphate (TPP)-binding riboswitch (THI-box) is found in all three kingdoms of life and can regulate gene expression at the levels of premature termination of transcription, initiation of translation and mRNA splicing. The THI-box is composed of two parallel stacked helices bound by another helix in a three-way junction. We performed an in vivo expression analysis of mutants with substitutions in conserved bases located at the interior and terminal loops of the Escherichia coli thiM THI-box, which is translationally regulated, and observed two different phenotypic classes. One class exhibited high expression during growth in the presence or absence of thiamin, while the second class exhibited low expression regardless of the presence of thiamin. Accessibility of the Shine-Dalgarno region of the RNA following the addition of TPP was monitored by means of an oligonucleotide-dependent RNase H cleavage assay, and binding of 30S ribosomal subunits. These studies showed that high- and low-expression mutant RNAs are locked in the non-repressive and repressive conformations respectively.
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Affiliation(s)
- Nancy Ontiveros-Palacios
- Depto. de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, México
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Gallivan JP. Toward reprogramming bacteria with small molecules and RNA. Curr Opin Chem Biol 2007; 11:612-9. [PMID: 17967431 DOI: 10.1016/j.cbpa.2007.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 10/01/2007] [Indexed: 12/23/2022]
Abstract
A major goal of synthetic biology is to reprogram bacteria to carry out complex tasks, such as synthesizing and delivering drugs, and seeking and destroying environmental pollutants. Advances in molecular biology and bacterial genetics have made it straightforward to modify, insert, or delete genes in many bacterial strains, and advances in gene synthesis have opened the door to replacing entire genomes. However, rewriting the underlying genetic code is only part of the challenge of reprogramming cellular behavior. A remaining challenge is to control how and when the modified genes are expressed. Several recent studies have highlighted how synthetic riboswitches, which are RNA sequences that undergo a ligand-induced conformational change to alter gene expression, can be used to reprogram how bacteria respond to small molecules.
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Affiliation(s)
- Justin P Gallivan
- Department of Chemistry and Center for Fundamental and Applied Molecular Evolution, Emory University, Atlanta, GA 30322, USA.
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