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Wu Y, Zhu L, Zhang Y, Xu W. Multidimensional Applications and Challenges of Riboswitches in Biosensing and Biotherapy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2304852. [PMID: 37658499 DOI: 10.1002/smll.202304852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/15/2023] [Indexed: 09/03/2023]
Abstract
Riboswitches have received significant attention over the last two decades for their multiple functionalities and great potential for applications in various fields. This article highlights and reviews the recent advances in biosensing and biotherapy. These fields involve a wide range of applications, such as food safety detection, environmental monitoring, metabolic engineering, live cell imaging, wearable biosensors, antibacterial drug targets, and gene therapy. The discovery, origin, and optimization of riboswitches are summarized to help readers better understand their multidimensional applications. Finally, this review discusses the multidimensional challenges and development of riboswitches in order to further expand their potential for novel applications.
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Affiliation(s)
- Yifan Wu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Longjiao Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Yangzi Zhang
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Wentao Xu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
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2
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Spirov A. Evolution of the RNA world: From signals to codes. Biosystems 2023; 234:105043. [PMID: 37852409 DOI: 10.1016/j.biosystems.2023.105043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 09/25/2023] [Accepted: 09/25/2023] [Indexed: 10/20/2023]
Abstract
The accumulated material in evolutionary biology, greatly enhanced by the achievements of modern synthetic biology, allows us to envision certain key hypothetical stages of prebiotic (chemical) evolution. This is often understood as the further evolution in the RNA World towards the RNA-protein World. It is a path towards the emergence of translation and the genetic code (I), signaling pathways with signaling molecules (II), and the appearance of RNA-based components of future gene regulatory networks (III). We believe that these evolutionary paths can be constructively viewed from the perspective of the concept of biological codes (Barbieri, 2003). Crucial evolutionary events in these directions would involve the emergence of RNA-based adaptors. Such adaptors connect two families of functionally and chemically distinct molecules into one functional entity. The emergence of primitive translation processes is undoubtedly the major milestone in the evolutionary path towards modern life. The key aspect here is the appearance of adaptors between amino acids and their cognate triplet codons. The initial steps are believed to involve the emergence of proto-transfer RNAs capable of self-aminoacylation. The second significant evolutionary breakthrough is the development of biochemical regulatory networks based on signaling molecules of the RNA World (ribonucleotides and their derivatives), as well as receptors and effectors (riboswitches) for these messengers. Some authors refer to this as the "lost language of the RNA World." The third evolutionary step is the emergence of signal sequences for ribozymes on the molecules of their RNA targets. This level of regulation in the RNA World is comparable to the gene regulatory networks of modern organisms. We believe that the signal sequences on target molecules have been rediscovered and developed by evolution into the gene regulatory networks of modern cells. In conclusion, the immense diversity of modern biological codes, in some of its key characteristics, can be traced back to the achievements of prebiotic evolution.
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Affiliation(s)
- Alexander Spirov
- The Institute of Scientific Information for Social Sciences RAS, Moscow, Russia.
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3
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Pavlova N, Traykovska M, Penchovsky R. Targeting FMN, TPP, SAM-I, and glmS Riboswitches with Chimeric Antisense Oligonucleotides for Completely Rational Antibacterial Drug Development. Antibiotics (Basel) 2023; 12:1607. [PMID: 37998809 PMCID: PMC10668854 DOI: 10.3390/antibiotics12111607] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/05/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023] Open
Abstract
Antimicrobial drug resistance has emerged as a significant challenge in contemporary medicine due to the proliferation of numerous bacterial strains resistant to all existing antibiotics. Meanwhile, riboswitches have emerged as promising targets for discovering antibacterial drugs. Riboswitches are regulatory elements in certain bacterial mRNAs that can bind to specific molecules and control gene expression via transcriptional termination, prevention of translation, or mRNA destabilization. By targeting riboswitches, we aim to develop innovative strategies to combat antibiotic-resistant bacteria and enhance the efficacy of antibacterial treatments. This convergence of challenges and opportunities underscores the ongoing quest to revolutionize medical approaches against evolving bacterial threats. For the first time, this innovative review describes the rational design and applications of chimeric antisense oligonucleotides as antibacterial agents targeting four riboswitches selected based on genome-wide bioinformatic analyses. The antisense oligonucleotides are coupled with the cell-penetrating oligopeptide pVEC, which penetrates Gram-positive and Gram-negative bacteria and specifically targets glmS, FMN, TPP, and SAM-I riboswitches in Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli. The average antibiotic dosage of antisense oligonucleotides that inhibits 80% of bacterial growth is around 700 nM (4.5 μg/mL). Antisense oligonucleotides do not exhibit toxicity in human cell lines at this concentration. The results demonstrate that these riboswitches are suitable targets for antibacterial drug development using antisense oligonucleotide technology. The approach is fully rational because selecting suitable riboswitch targets and designing ASOs that target them are based on predefined criteria. The approach can be used to develop narrow or broad-spectrum antibiotics against multidrug-resistant bacterial strains for a short time. The approach is easily adaptive to new resistance using targeting NGS technology.
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Affiliation(s)
| | | | - Robert Penchovsky
- Laboratory of Synthetic Biology and Bioinformatics, Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Blvd., 1164 Sofia, Bulgaria
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4
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Sung HL, Nesbitt DJ. Ligand-Dependent Volumetric Characterization of Manganese Riboswitch Folding: A High-Pressure Single-Molecule Kinetic Study. J Phys Chem B 2022; 126:9781-9789. [PMID: 36399551 DOI: 10.1021/acs.jpcb.2c06579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Nanoscopic differences in free volume result in pressure-dependent changes in free energies which can therefore impact folding/unfolding stability of biomolecules. Although such effects are typically insignificant under ambient pressure conditions, they are crucially important for deep ocean marine life, where the hydraulic pressure can be on the kilobar scale. In this work, single molecule FRET spectroscopy is used to study the effects of pressure on both the kinetics and overall thermodynamics for folding/unfolding of the manganese riboswitch. Detailed pressure-dependent analysis of the conformational kinetics allows one to extract precision changes (σ ≲ 4-8 Å3) in free volumes not only between the fully folded/unfolded conformations but also with respect to the folding transition state of the manganese riboswitch. This permits first extraction of a novel "reversible work" free energy (PΔV) landscape, which reveals a monotonic increase in manganese riboswitch volume along the folding coordinate. Furthermore, such a tool permits exploration of pressure-dependent effects on both Mn2+ binding and riboswitch folding, which demonstrate that ligand attachment stabilizes the riboswitch under pressure by decreasing the volume increase upon folding (ΔΔV < 0). Such competition between ligand binding and pressure-induced denaturation dynamics could be of significant evolutionary advantage, compensating for a weakening in riboswitch tertiary structure with pressure-mediated ligand binding and promotion of folding response.
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Affiliation(s)
- Hsuan-Lei Sung
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.,Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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5
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Vikram, Mishra V, Rana A, Ahire JJ. Riboswitch-mediated regulation of riboflavin biosynthesis genes in prokaryotes. 3 Biotech 2022; 12:278. [PMID: 36275359 PMCID: PMC9474784 DOI: 10.1007/s13205-022-03348-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 09/02/2022] [Indexed: 11/01/2022] Open
Abstract
Prokaryotic organisms frequently use riboswitches to quantify intracellular metabolite concentration via high-affinity metabolite receptors. Riboswitches possess a metabolite-sensing system that controls gene regulation in a cis-acting fashion at the initiation of transcriptional/translational level by binding with a specific metabolite and controlling various biochemical pathways. Riboswitch binds with flavin mononucleotide (FMN), a phosphorylated form of riboflavin and controls gene expression involved in riboflavin biosynthesis and transport pathway. The first step of the riboflavin biosynthesis pathway is initiated by the conversion of guanine nucleotide triphosphate (GTP), which is an intermediate of the purine biosynthesis pathway. An alternative pentose phosphate pathway of riboflavin biosynthesis includes the enzymatic conversion of ribulose-5-phosphate into 3, 4 dihydroxy-2-butanone-4-phosphates by DHBP synthase. The product of ribAB interferes with both GTP cyclohydrolase II as well as DHBP synthase activities, which catalyze the cleavage of GTP and converts DHBP Ribu5P in the initial steps of both riboflavin biosynthesis branches. Riboswitches are located in the 5' untranslated region (5' UTR) of messenger RNAs and contain an aptamer domain (highly conserved in sequence) where metabolite binding leads to a conformational change in an aptamer domain, which modulate the regulation of gene expression located on bacterial mRNA. In this review, we focus on how riboswitch regulates the riboflavin biosynthesis pathway in Bacillus subtilis and Lactobacillus plantarum.
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Affiliation(s)
- Vikram
- Department of Basic and Applied Sciences, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonipat, Haryana India
| | - Vijendra Mishra
- Department of Basic and Applied Sciences, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonipat, Haryana India
| | - Ananya Rana
- Department of Basic and Applied Sciences, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonipat, Haryana India
| | - Jayesh J. Ahire
- Centre for Research and Development, Unique Biotech Ltd., Plot No. 2, Phase II, MN Park, Hyderabad, Telangana India
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Alam KM, Yan Y, Lin M, Islam MA, Gaber A, Hossain A. Insight rifampicin-resistant (rpoB) mutation in Pseudomonas stutzeri leads to enhance the biosynthesis of secondary metabolites to survive against harsh environments. Arch Microbiol 2022; 204:437. [PMID: 35768665 DOI: 10.1007/s00203-022-03064-9] [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: 02/18/2022] [Revised: 05/24/2022] [Accepted: 06/07/2022] [Indexed: 11/02/2022]
Abstract
In this study, a wild-type and five distinct rifampicin-resistant (Rifr) rpoB mutants of Pseudomonas stutzeri (i.e., Q518R, D521Y, D521V, H531R and I614T) ability were investigated against harsh environments (particularly nutritional complexity). Among these, the robust Rifr phenotype of P. Stutzeri was associated only with base replacements of the amino deposits. The use of carboxylic and amino acids significantly increased in various Rifr mutants than that of wild type of P. stutzeri. The assimilation of carbon and nitrogen (N) sources of Rifr mutants' confirmed that the organism maintains the adaptation in nutritionally complex environments. Acetylene reduction assay at different times also found the variability for N-fixation in all strains. Among them, the highest nitrogenase activity was determined in mutant 'D521V'. The assimilation of carbon and nitrogen sources of P. stutzeri and its Rifr mutants ensures that the organism maintains the adaptability in nutritionally complex environments through fixing more nitrogen.
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Affiliation(s)
- Khandakar Mohiul Alam
- Soils and Nutrition Division, Bangladesh Sugarcrop Research Institute, Pabna, 6620, Bangladesh
| | - Yongliang Yan
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South StHaidian District, Beijing, People's Republic of China
| | - Min Lin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South StHaidian District, Beijing, People's Republic of China
| | - Md Ariful Islam
- On-Farm Research Division, Bangladesh Agricultural Research Institute, Pabna, 6600, Bangladesh
| | - Ahmed Gaber
- Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif, 21944, Saudi Arabia
| | - Akbar Hossain
- Department of Agronomy, Bangladesh Wheat and Maize Research Institute, Dinajpur, 5200, Bangladesh.
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Schamber T, Binas O, Schlundt A, Wacker A, Schwalbe H. Characterization of Structure and Dynamics of the Guanidine-II Riboswitch from Escherichia coli by NMR Spectroscopy and Small-Angle X-ray Scattering (SAXS). Chembiochem 2022; 23:e202100564. [PMID: 34847270 PMCID: PMC9300104 DOI: 10.1002/cbic.202100564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/30/2021] [Indexed: 11/12/2022]
Abstract
Riboswitches are regulatory RNA elements that undergo functionally important allosteric conformational switching upon binding of specific ligands. The here investigated guanidine-II riboswitch binds the small cation, guanidinium, and forms a kissing loop-loop interaction between its P1 and P2 hairpins. We investigated the structural changes to support previous studies regarding the binding mechanism. Using NMR spectroscopy, we confirmed the structure as observed in crystal structures and we characterized the kissing loop interaction upon addition of Mg2+ and ligand for the riboswitch aptamer from Escherichia coli. We further investigated closely related mutant constructs providing further insight into functional differences between the two (different) hairpins P1 and P2. Formation of intermolecular interactions were probed by small-angle X-ray scattering (SAXS) and NMR DOSY data. All data are consistent and show the formation of oligomeric states of the riboswitch induced by Mg2+ and ligand binding.
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Affiliation(s)
- Tatjana Schamber
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Oliver Binas
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Andreas Schlundt
- Institute for Molecular BiosciencesJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 960438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
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8
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Farah N, Chin VK, Chong PP, Lim WF, Lim CW, Basir R, Chang SK, Lee TY. Riboflavin as a promising antimicrobial agent? A multi-perspective review. CURRENT RESEARCH IN MICROBIAL SCIENCES 2022; 3:100111. [PMID: 35199072 PMCID: PMC8848291 DOI: 10.1016/j.crmicr.2022.100111] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 12/29/2022] Open
Abstract
Riboflavin demonstrates antioxidant and photosensitizing properties. Riboflavin is able to induce ROS and modulate immune response. Riboflavin possesses potent antimicrobial activity when used alone or combined with other anti-infectives. The riboflavin biosynthesis pathway serves as an ideal drug target against microbes. UVA combination with riboflavin exhibits remarkable antimicrobial effects.
Riboflavin, or more commonly known as vitamin B2, forms part of the component of vitamin B complex. Riboflavin consisting of two important cofactors, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are involved in multiple oxidative-reduction processes and energy metabolism. Besides maintaining human health, different sources reported that riboflavin can inhibit or inactivate the growth of different pathogens including bacteria, viruses, fungi and parasites, highlighting the possible role of riboflavin as an antimicrobial agent. Moreover, riboflavin and flavins could produce reactive oxygen species (ROS) when exposed to light, inducing oxidative damage in cells and tissues, and thus are excellent natural photosensitizers. Several studies have illustrated the therapeutic efficacy of photoactivated riboflavin against nosocomial infections and multidrug resistant bacterial infections as well as microbial associated biofilm infections, revealing the potential role of riboflavin as a promising antimicrobial candidate, which could serve as one of the alternatives in fighting the global crisis of the emergence of antimicrobial resistance seen in different pathogenic microbes. Riboflavin could also be involved in modulating host immune responses, which might increase the pathogen clearance from host cells and increase host defense against microbial infections. Thus, the dual effects of riboflavin on both pathogens and host immunity, reflected by its potent bactericidal effect and alleviation of inflammation in host cells further imply that riboflavin could be a potential candidate for therapeutic intervention in resolving microbial infections. Hence, this review aimed to provide some insights on the promising role of riboflavin as an antimicrobial candidate and also a host immune-modulator from a multi-perspective view as well as to discuss the application and challenges on using riboflavin in photodynamic therapy against various pathogens and microbial biofilm-associated infections.
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Affiliation(s)
- Nuratiqah Farah
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, UPM, 43400, Serdang, Selangor, Malaysia
| | - Voon Kin Chin
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, UPM, 43400, Serdang, Selangor, Malaysia
| | - Pei Pei Chong
- School of Biosciences, Taylor's University, No 1, Jalan Taylor's, 47500 Subang Jaya, Selangor, Malaysia
| | - Wai Feng Lim
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Puncak Alam Campus, 42300 Bandar Puncak Alam, Selangor, Malaysia
| | - Chee Woei Lim
- Department of Medicine, Faculty of Medicine and Health Sciences, UPM, 43400, Serdang, Selangor, Malaysia
| | - Rusliza Basir
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, UPM, 43400, Serdang, Selangor, Malaysia
| | - Sui Kiat Chang
- Department of Horticulture, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Key Laboratory of Post-Harvest Handling of Fruits, Ministry of Agriculture. South China Botanical Garden, Chinese Academy of Sciences. Guangzhou, 510650 China
| | - Tze Yan Lee
- Perdana University School of Liberal Arts, Science and Technology (PUScLST), Suite 9.2, 9th Floor, Wisma Chase Perdana, Changkat Semantan, Damansara Heights, 50490 Kuala Lumpur, Malaysia
- Corresponding author.
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9
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Regulation of Glycine Cleavage and Detoxification by a Highly Conserved Glycine Riboswitch in Burkholderia spp. Curr Microbiol 2021; 78:2943-2955. [PMID: 34076709 DOI: 10.1007/s00284-021-02550-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 05/21/2021] [Indexed: 10/21/2022]
Abstract
The glycine riboswitch is a known regulatory element that is unique in having two aptamers that are joined by a linker region. In this study, we investigated a glycine riboswitch located in the 5' untranslated region of a glycine cleavage system homolog (gcvTHP) in Burkholderia spp. Structure prediction using the sequence generated a model with a glycine binding pocket composed of base-triple interactions (G62-A64-A86 and G65-U84-C85) that are supported by A/G minor interactions (A17-C60-G88 and G16-C61-G87, respectively) and two ribose-zipper motifs (C11-G12 interacting with A248-A247 and C153-U154 interacting with A79-A78) which had not been previously reported. The capacity of the riboswitch to bind to glycine was experimentally validated by native gel assays and the crucial role of interactions that make up the glycine binding pocket were proven by mutations of A17U and G16C which resulted in conformational differences that may lead to dysfunction. Using glycine supplemented minimal media, we were able to prove that the expression of the gcvTHP genes found downstream of the riboswitch responded to the glycine concentrations introduced thus confirming the role of this highly conserved Burkholderia riboswitch and its associated genes as a putative glycine detoxification system in Burkholderia spp.
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10
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Droste J, Rückert C, Kalinowski J, Hamed MB, Anné J, Simoens K, Bernaerts K, Economou A, Busche T. Extensive Reannotation of the Genome of the Model Streptomycete Streptomyces lividans TK24 Based on Transcriptome and Proteome Information. Front Microbiol 2021; 12:604034. [PMID: 33935985 PMCID: PMC8079986 DOI: 10.3389/fmicb.2021.604034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 03/12/2021] [Indexed: 01/04/2023] Open
Abstract
Streptomyces lividans TK24 is a relevant Gram-positive soil inhabiting bacterium and one of the model organisms of the genus Streptomyces. It is known for its potential to produce secondary metabolites, antibiotics, and other industrially relevant products. S. lividans TK24 is the plasmid-free derivative of S. lividans 66 and a close genetic relative of the strain Streptomyces coelicolor A3(2). In this study, we used transcriptome and proteome data to improve the annotation of the S. lividans TK24 genome. The RNA-seq data of primary 5'-ends of transcripts were used to determine transcription start sites (TSS) in the genome. We identified 5,424 TSS, of which 4,664 were assigned to annotated CDS and ncRNAs, 687 to antisense transcripts distributed between 606 CDS and their UTRs, 67 to tRNAs, and 108 to novel transcripts and CDS. Using the TSS data, the promoter regions and their motifs were analyzed in detail, revealing a conserved -10 (TAnnnT) and a weakly conserved -35 region (nTGACn). The analysis of the 5' untranslated region (UTRs) of S. lividans TK24 revealed 17% leaderless transcripts. Several cis-regulatory elements, like riboswitches or attenuator structures could be detected in the 5'-UTRs. The S. lividans TK24 transcriptome contains at least 929 operons. The genome harbors 27 secondary metabolite gene clusters of which 26 could be shown to be transcribed under at least one of the applied conditions. Comparison of the reannotated genome with that of the strain Streptomyces coelicolor A3(2) revealed a high degree of similarity. This study presents an extensive reannotation of the S. lividans TK24 genome based on transcriptome and proteome analyses. The analysis of TSS data revealed insights into the promoter structure, 5'-UTRs, cis-regulatory elements, attenuator structures and novel transcripts, like small RNAs. Finally, the repertoire of secondary metabolite gene clusters was examined. These data provide a basis for future studies regarding gene characterization, transcriptional regulatory networks, and usage as a secondary metabolite producing strain.
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Affiliation(s)
- Julian Droste
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Christian Rückert
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Jörn Kalinowski
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Mohamed Belal Hamed
- Laboratory of Molecular Bacteriology, Department of Microbiology and Immunology, KU Leuven, Rega Institute, Leuven, Belgium.,Molecular Biology Department, National Research Centre, Dokii, Egypt
| | - Jozef Anné
- Laboratory of Molecular Bacteriology, Department of Microbiology and Immunology, KU Leuven, Rega Institute, Leuven, Belgium
| | - Kenneth Simoens
- Bio- and Chemical Systems Technology, Reactor Engineering, and Safety (CREaS) Section, Department of Chemical Engineering, KU Leuven, Leuven, Belgium
| | - Kristel Bernaerts
- Bio- and Chemical Systems Technology, Reactor Engineering, and Safety (CREaS) Section, Department of Chemical Engineering, KU Leuven, Leuven, Belgium
| | - Anastassios Economou
- Laboratory of Molecular Bacteriology, Department of Microbiology and Immunology, KU Leuven, Rega Institute, Leuven, Belgium
| | - Tobias Busche
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
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11
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Schroeder GM, Dutta D, Cavender CE, Jenkins J, Pritchett EM, Baker CD, Ashton JM, Mathews DH, Wedekind JE. Analysis of a preQ1-I riboswitch in effector-free and bound states reveals a metabolite-programmed nucleobase-stacking spine that controls gene regulation. Nucleic Acids Res 2020; 48:8146-8164. [PMID: 32597951 PMCID: PMC7641330 DOI: 10.1093/nar/gkaa546] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/13/2020] [Accepted: 06/16/2020] [Indexed: 01/20/2023] Open
Abstract
Riboswitches are structured RNA motifs that recognize metabolites to alter the conformations of downstream sequences, leading to gene regulation. To investigate this molecular framework, we determined crystal structures of a preQ1-I riboswitch in effector-free and bound states at 2.00 Å and 2.65 Å-resolution. Both pseudoknots exhibited the elusive L2 loop, which displayed distinct conformations. Conversely, the Shine-Dalgarno sequence (SDS) in the S2 helix of each structure remained unbroken. The expectation that the effector-free state should expose the SDS prompted us to conduct solution experiments to delineate environmental changes to specific nucleobases in response to preQ1. We then used nudged elastic band computational methods to derive conformational-change pathways linking the crystallographically-determined effector-free and bound-state structures. Pathways featured: (i) unstacking and unpairing of L2 and S2 nucleobases without preQ1-exposing the SDS for translation and (ii) stacking and pairing L2 and S2 nucleobases with preQ1-sequestering the SDS. Our results reveal how preQ1 binding reorganizes L2 into a nucleobase-stacking spine that sequesters the SDS, linking effector recognition to biological function. The generality of stacking spines as conduits for effector-dependent, interdomain communication is discussed in light of their existence in adenine riboswitches, as well as the turnip yellow mosaic virus ribosome sensor.
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Affiliation(s)
- Griffin M Schroeder
- Department of Biochemistry & Biophysics, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Debapratim Dutta
- Department of Biochemistry & Biophysics, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Chapin E Cavender
- Department of Biochemistry & Biophysics, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Jermaine L Jenkins
- Department of Biochemistry & Biophysics, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Elizabeth M Pritchett
- Genomics Research Center, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Cameron D Baker
- Genomics Research Center, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - John M Ashton
- Genomics Research Center, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Joseph E Wedekind
- Department of Biochemistry & Biophysics, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
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12
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Hernandez-Valdes JA, van Gestel J, Kuipers OP. A riboswitch gives rise to multi-generational phenotypic heterogeneity in an auxotrophic bacterium. Nat Commun 2020; 11:1203. [PMID: 32139702 PMCID: PMC7058034 DOI: 10.1038/s41467-020-15017-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/13/2020] [Indexed: 12/26/2022] Open
Abstract
Auxotrophy, the inability to produce an organic compound essential for growth, is widespread among bacteria. Auxotrophic bacteria rely on transporters to acquire these compounds from their environment. Here, we study the expression of both low- and high-affinity transporters of the costly amino acid methionine in an auxotrophic lactic acid bacterium, Lactococcus lactis. We show that the high-affinity transporter (Met-transporter) is heterogeneously expressed at low methionine concentrations, resulting in two isogenic subpopulations that sequester methionine in different ways: one subpopulation primarily relies on the high-affinity transporter (high expression of the Met-transporter) and the other subpopulation primarily relies on the low-affinity transporter (low expression of the Met-transporter). The phenotypic heterogeneity is remarkably stable, inherited for tens of generations, and apparent at the colony level. This heterogeneity results from a T-box riboswitch in the promoter region of the met operon encoding the high-affinity Met-transporter. We hypothesize that T-box riboswitches, which are commonly found in the Lactobacillales, may play as-yet unexplored roles in the predominantly auxotrophic lifestyle of these bacteria.
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Affiliation(s)
- Jhonatan A Hernandez-Valdes
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, Netherlands
| | - Jordi van Gestel
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Oscar P Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, Netherlands.
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13
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McCluskey K, Boudreault J, St-Pierre P, Perez-Gonzalez C, Chauvier A, Rizzi A, Beauregard PB, Lafontaine DA, Penedo JC. Unprecedented tunability of riboswitch structure and regulatory function by sub-millimolar variations in physiological Mg2. Nucleic Acids Res 2020; 47:6478-6487. [PMID: 31045204 PMCID: PMC6614840 DOI: 10.1093/nar/gkz316] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 04/16/2019] [Accepted: 04/18/2019] [Indexed: 02/06/2023] Open
Abstract
Riboswitches are cis-acting regulatory RNA biosensors that rival the efficiency of those found in proteins. At the heart of their regulatory function is the formation of a highly specific aptamer–ligand complex. Understanding how these RNAs recognize the ligand to regulate gene expression at physiological concentrations of Mg2+ ions and ligand is critical given their broad impact on bacterial gene expression and their potential as antibiotic targets. In this work, we used single-molecule FRET and biochemical techniques to demonstrate that Mg2+ ions act as fine-tuning elements of the amino acid-sensing lysC aptamer's ligand-free structure in the mesophile Bacillus subtilis. Mg2+ interactions with the aptamer produce encounter complexes with strikingly different sensitivities to the ligand in different, yet equally accessible, physiological ionic conditions. Our results demonstrate that the aptamer adapts its structure and folding landscape on a Mg2+-tunable scale to efficiently respond to changes in intracellular lysine of more than two orders of magnitude. The remarkable tunability of the lysC aptamer by sub-millimolar variations in the physiological concentration of Mg2+ ions suggests that some single-aptamer riboswitches have exploited the coupling of cellular levels of ligand and divalent metal ions to tightly control gene expression.
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Affiliation(s)
- Kaley McCluskey
- SUPA School of Physics and Astronomy, University of St. Andrews, Scotland KY16 9SS, UK
| | - Julien Boudreault
- Département de Biologie, Université de Sherbrooke, Québec, Canada J1K 2R1
| | - Patrick St-Pierre
- Département de Biologie, Université de Sherbrooke, Québec, Canada J1K 2R1
| | - Cibran Perez-Gonzalez
- SUPA School of Physics and Astronomy, University of St. Andrews, Scotland KY16 9SS, UK.,Centre SÈVE, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Canada
| | - Adrien Chauvier
- Département de Biologie, Université de Sherbrooke, Québec, Canada J1K 2R1
| | - Adrien Rizzi
- Département de Chimie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Canada
| | - Pascale B Beauregard
- Centre SÈVE, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Canada
| | | | - J Carlos Penedo
- SUPA School of Physics and Astronomy, University of St. Andrews, Scotland KY16 9SS, UK.,Biomedical Sciences Research Complex, School of Biology, University of St. Andrews, Scotland KY16 9ST, UK
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14
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Li S, Su Z, Lehmann J, Stamatopoulou V, Giarimoglou N, Henderson FE, Fan L, Pintilie GD, Zhang K, Chen M, Ludtke SJ, Wang YX, Stathopoulos C, Chiu W, Zhang J. Structural basis of amino acid surveillance by higher-order tRNA-mRNA interactions. Nat Struct Mol Biol 2019; 26:1094-1105. [PMID: 31740854 PMCID: PMC6899168 DOI: 10.1038/s41594-019-0326-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/07/2019] [Indexed: 12/11/2022]
Abstract
Amino acid availability in Gram-positive bacteria is monitored by T-box riboswitches. T-boxes directly bind tRNAs, assess their aminoacylation state, and regulate the transcription or translation of downstream genes to maintain nutritional homeostasis. Here, we report cocrystal and cryo-EM structures of Geobacillus kaustophilus and Bacillus subtilis T-box-tRNA complexes, detailing their multivalent, exquisitely selective interactions. The T-box forms a U-shaped molecular vise that clamps the tRNA, captures its 3' end using an elaborate 'discriminator' structure, and interrogates its aminoacylation state using a steric filter fashioned from a wobble base pair. In the absence of aminoacylation, T-boxes clutch tRNAs and form a continuously stacked central spine, permitting transcriptional readthrough or translation initiation. A modeled aminoacyl disrupts tRNA-T-box stacking, severing the central spine and blocking gene expression. Our data establish a universal mechanism of amino acid sensing on tRNAs and gene regulation by T-box riboswitches and exemplify how higher-order RNA-RNA interactions achieve multivalency and specificity.
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Affiliation(s)
- Shuang Li
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Zhaoming Su
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Jean Lehmann
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Campus Paris-Saclay, Gif-sur-Yvette, France
| | | | - Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, Patras, Greece
| | - Frances E Henderson
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Lixin Fan
- Small-Angle X-ray Scattering Core Facility, Center for Cancer Research of the National Cancer Institute, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc, Frederick, MD, USA
| | - Grigore D Pintilie
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Kaiming Zhang
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Muyuan Chen
- Verna Marrs and McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Steven J Ludtke
- Verna Marrs and McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Yun-Xing Wang
- Small-Angle X-ray Scattering Core Facility, Center for Cancer Research of the National Cancer Institute, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc, Frederick, MD, USA.,Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | | | - Wah Chiu
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA. .,Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, Stanford University, Stanford, CA, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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15
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Sung HL, Nesbitt DJ. Single-Molecule FRET Kinetics of the Mn 2+ Riboswitch: Evidence for Allosteric Mg 2+ Control of "Induced-Fit" vs "Conformational Selection" Folding Pathways. J Phys Chem B 2019; 123:2005-2015. [PMID: 30739441 DOI: 10.1021/acs.jpcb.8b11841] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gene expression in bacteria is often regulated dynamically by conformational changes in a riboswitch upon ligand binding, a detailed understanding of which is very much in its infancy. For example, the manganese riboswitch is a widespread RNA motif that conformationally responds in regulating bacterial gene expression to micromolar levels of its eponymous ligand, Mn2+, but the mechanistic pathways are poorly understood. In this work, we quantitatively explore the dynamic folding behavior of the manganese riboswitch by single-molecule fluorescence resonance energy transfer spectroscopy as a function of cation/ligand conditions. From the detailed analysis of the kinetics, the Mn2+ is shown to fold the riboswitch by a "bind-then-fold" (i.e., "induced-fit", IF) mechanism, whereby the ligand binds first and then promotes folding. On the other hand, the data also clearly reveal the presence of a folded yet ligand-free structure predominating due to the addition of physiological Mg2+ to a nonselective metal ion binding site. Of particular kinetic interest, such a Mg2+ "prefolded" conformation of the riboswitch is shown to exhibit a significantly increased affinity for Mn2+ and further stabilization by subsequent binding of the ligand, thereby promoting efficient riboswitch folding by a "fold-then-bind" (i.e., "conformational selection", CS) mechanism. Our results not only demonstrate Mg2+-controlled switching between IF and CS riboswitch folding pathways but also suggest a novel heterotropic allosteric control in the manganese riboswitch activity co-regulated by Mg2+ binding.
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16
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Zhang JL, Wang D, Liang YW, Zhong WY, Ming ZH, Tang DJ, Tang JL. The Gram-negative phytopathogen Xanthomonas campestris pv. campestris employs a 5'UTR as a feedback controller to regulate methionine biosynthesis. MICROBIOLOGY-SGM 2018; 164:1146-1155. [PMID: 30024369 PMCID: PMC6230763 DOI: 10.1099/mic.0.000690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The synthesis of methionine is critical for most bacteria. It is known that cellular methionine has a feedback effect on the expression of met genes involved in de novo methionine biosynthesis. Previous studies revealed that Gram-negative bacteria control met gene expression at the transcriptional level by regulator proteins, while most Gram-positive bacteria regulate met genes at post-transcriptional level by RNA regulators (riboregulators) located in the 5′UTR of met genes. However, despite its importance, the methionine biosynthesis pathway in the Gram-negative Xanthomonas genus that includes many important plant pathogens is completely uncharacterized. Here, we address this issue using the crucifer black rot pathogen Xanthomonas campestris pv. campestris (Xcc), a model bacterium in microbe–plant interaction studies. The work identified an operon (met) involved in de novo methionine biosynthesis in Xcc. Disruption of the operon resulted in defective growth in methionine-limited media and in planta. Western blot analysis revealed that the expression of the operon is dependent on methionine levels. Further molecular analyses demonstrated that the 5′UTR, but not the promoter of the operon, is involved in feedback regulation on operon expression in response to methionine availability, providing an example of a Gram-negative bacterium utilizing a 5′UTR region to control the expression of the genes involved in methionine biosynthesis.
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Affiliation(s)
- Jian-Ling Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Dan Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Yu-Wei Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Wan-Ying Zhong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Zhen-Hua Ming
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Dong-Jie Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
- *Correspondence: Dong-Jie Tang,
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
- Ji-Liang Tang,
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17
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McCluskey K, Carlos Penedo J. An integrated perspective on RNA aptamer ligand-recognition models: clearing muddy waters. Phys Chem Chem Phys 2018; 19:6921-6932. [PMID: 28225108 DOI: 10.1039/c6cp08798a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Riboswitches are short RNA motifs that sensitively and selectively bind cognate ligands to modulate gene expression. Like protein receptor-ligand pairs, their binding dynamics are traditionally categorized as following one of two paradigmatic mechanisms: conformational selection and induced fit. In conformational selection, ligand binding stabilizes a particular state already present in the receptor's dynamic ensemble. In induced fit, ligand-receptor interactions enable the system to overcome the energetic barrier into a previously inaccessible state. In this article, we question whether a polarized division of RNA binding mechanisms truly meets the conceptual needs of the field. We will review the history behind this classification of RNA-ligand interactions, and the way induced fit in particular has been rehabilitated by single-molecule studies of RNA aptamers. We will highlight several recent results from single-molecule experimental studies of riboswitches that reveal gaps or even contradictions between common definitions of the two terms, and we will conclude by proposing a more robust framework that considers the range of RNA behaviors unveiled in recent years as a reality to be described, rather than an increasingly unwieldy set of exceptions to the traditional models.
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Affiliation(s)
- K McCluskey
- Department of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK.
| | - J Carlos Penedo
- Department of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK. and Biomolecular Sciences Research Complex, University of St. Andrews, St. Andrews, KY16 9SS, UK.
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18
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Khani A, Popp N, Kreikemeyer B, Patenge N. A Glycine Riboswitch in Streptococcus pyogenes Controls Expression of a Sodium:Alanine Symporter Family Protein Gene. Front Microbiol 2018. [PMID: 29527194 PMCID: PMC5829553 DOI: 10.3389/fmicb.2018.00200] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Regulatory RNAs play important roles in the control of bacterial gene expression. In this study, we investigated gene expression regulation by a putative glycine riboswitch located in the 5'-untranslated region of a sodium:alanine symporter family (SAF) protein gene in the group A Streptococcus pyogenes serotype M49 strain 591. Glycine-dependent gene expression mediated by riboswitch activity was studied using a luciferase reporter gene system. Maximal reporter gene expression was observed in the absence of glycine and in the presence of low glycine concentrations. Differences in glycine-dependent gene expression were not based on differential promoter activity. Expression of the SAF protein gene and the downstream putative cation efflux protein gene was investigated in wild-type bacteria by RT-qPCR transcript analyses. During growth in the presence of glycine (≥1 mM), expression of the genes were downregulated. Northern blot analyses revealed premature transcription termination in the presence of high glycine concentrations. Growth in the presence of 0.1 mM glycine led to the production of a full-length transcript. Furthermore, stability of the SAF protein gene transcript was drastically reduced in the presence of glycine. We conclude that the putative glycine riboswitch in S. pyogenes serotype M49 strain 591 represses expression of the SAF protein gene and the downstream putative cation efflux protein gene in the presence of high glycine concentrations. Sequence and secondary structure comparisons indicated that the streptococcal riboswitch belongs to the class of tandem aptamer glycine riboswitches.
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Affiliation(s)
- Afsaneh Khani
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Nicole Popp
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Bernd Kreikemeyer
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Nadja Patenge
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
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19
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Studying Parasite Gene Function and Interaction Through Ribozymes and Riboswitches Design Mechanism. Synth Biol (Oxf) 2018. [DOI: 10.1007/978-981-10-8693-9_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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20
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McNerney MP, Styczynski MP. Small molecule signaling, regulation, and potential applications in cellular therapeutics. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 10. [PMID: 28960879 DOI: 10.1002/wsbm.1405] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 07/20/2017] [Accepted: 08/14/2017] [Indexed: 12/19/2022]
Abstract
Small molecules have many important roles across the tree of life: they regulate processes from metabolism to transcription, they enable signaling within and between species, and they serve as the biochemical building blocks for cells. They also represent valuable phenotypic endpoints that are promising for use as biomarkers of disease states. In the context of engineering cell-based therapeutics, they hold particularly great promise for enabling finer control over the therapeutic cells and allowing them to be responsive to extracellular cues. The natural signaling and regulatory functions of small molecules can be harnessed and rewired to control cell activity and delivery of therapeutic payloads, potentially increasing efficacy while decreasing toxicity. To that end, this review considers small molecule-mediated regulation and signaling in bacteria. We first discuss some of the most prominent applications and aspirations for responsive cell-based therapeutics. We then describe the transport, signaling, and regulation associated with three classes of molecules that may be exploited in the engineering of therapeutic bacteria: amino acids, fatty acids, and quorum-sensing signaling molecules. We also present examples of existing engineering efforts to generate cells that sense and respond to levels of different small molecules. Finally, we discuss future directions for how small molecule-mediated regulation could be harnessed for therapeutic applications, as well as some critical considerations for the ultimate success of such endeavors. WIREs Syst Biol Med 2018, 10:e1405. doi: 10.1002/wsbm.1405 This article is categorized under: Biological Mechanisms > Cell Signaling Biological Mechanisms > Metabolism Translational, Genomic, and Systems Medicine > Therapeutic Methods.
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Affiliation(s)
- Monica P McNerney
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Mark P Styczynski
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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21
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Mukherjee S, Barash D, Sengupta S. Comparative genomics and phylogenomic analyses of lysine riboswitch distributions in bacteria. PLoS One 2017; 12:e0184314. [PMID: 28873470 PMCID: PMC5584792 DOI: 10.1371/journal.pone.0184314] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 08/22/2017] [Indexed: 12/22/2022] Open
Abstract
Riboswitches are cis-regulatory elements that regulate the expression of genes involved in biosynthesis or transport of a ligand that binds to them. Among the nearly 40 classes of riboswitches discovered so far, three are known to regulate the concentration of biologically encoded amino acids glycine, lysine, and glutamine. While some comparative genomics studies of riboswitches focusing on their gross distribution across different bacterial taxa have been carried out recently, systematic functional annotation and analysis of lysine riboswitches and the genes they regulate are still lacking. We analyzed 2785 complete bacterial genome sequences to systematically identify 468 lysine riboswitches (not counting hits from multiple strains of the same species) and obtain a detailed phylogenomic map of gene-specific lysine riboswitch distribution across diverse prokaryotic phyla. We find that lysine riboswitches are most abundant in Firmicutes and Gammaproteobacteria where they are found upstream to both biosynthesis and/or transporter genes. They are relatively rare in all other prokaryotic phyla where if present they are primarily found upstream to operons containing many lysine biosynthesis genes. The genome-wide study of the genetic organisation of the lysine riboswitches show considerable variation both within and across different Firmicute orders. Correlating the location of a riboswitch with its genomic context and its phylogenetic relationship with other evolutionarily related riboswitch carrying species, enables identification and annotation of many lysine biosynthesis, transporter and catabolic genes. It also reveals previously unknown patterns of lysine riboswitch distribution and gene/operon regulation and allows us to draw inferences about the possible point of origin of lysine riboswitches. Additionally, evidence of horizontal transfer of riboswitches was found between Firmicutes and Actinobacteria. Our analysis provides a useful resource that will lead to a better understanding of the evolution of these regulatory elements and prove to be beneficial for exploiting riboswitches for developing targeted therapies.
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Affiliation(s)
- Sumit Mukherjee
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
| | - Danny Barash
- Department of Computer Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Supratim Sengupta
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
- * E-mail:
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22
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Frozen Accident Pushing 50: Stereochemistry, Expansion, and Chance in the Evolution of the Genetic Code. Life (Basel) 2017; 7:life7020022. [PMID: 28545255 PMCID: PMC5492144 DOI: 10.3390/life7020022] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/19/2017] [Accepted: 05/20/2017] [Indexed: 12/31/2022] Open
Abstract
Nearly 50 years ago, Francis Crick propounded the frozen accident scenario for the evolution of the genetic code along with the hypothesis that the early translation system consisted primarily of RNA. Under the frozen accident perspective, the code is universal among modern life forms because any change in codon assignment would be highly deleterious. The frozen accident can be considered the default theory of code evolution because it does not imply any specific interactions between amino acids and the cognate codons or anticodons, or any particular properties of the code. The subsequent 49 years of code studies have elucidated notable features of the standard code, such as high robustness to errors, but failed to develop a compelling explanation for codon assignments. In particular, stereochemical affinity between amino acids and the cognate codons or anticodons does not seem to account for the origin and evolution of the code. Here, I expand Crick’s hypothesis on RNA-only translation system by presenting evidence that this early translation already attained high fidelity that allowed protein evolution. I outline an experimentally testable scenario for the evolution of the code that combines a distinct version of the stereochemical hypothesis, in which amino acids are recognized via unique sites in the tertiary structure of proto-tRNAs, rather than by anticodons, expansion of the code via proto-tRNA duplication, and the frozen accident.
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23
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Jones CP, Ferré-D'Amaré AR. Long-Range Interactions in Riboswitch Control of Gene Expression. Annu Rev Biophys 2017; 46:455-481. [PMID: 28375729 DOI: 10.1146/annurev-biophys-070816-034042] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Riboswitches are widespread RNA motifs that regulate gene expression in response to fluctuating metabolite concentrations. Known primarily from bacteria, riboswitches couple specific ligand binding and changes in RNA structure to mRNA expression in cis. Crystal structures of the ligand binding domains of most of the phylogenetically widespread classes of riboswitches, each specific to a particular metabolite or ion, are now available. Thus, the bound states-one end point-have been thoroughly characterized, but the unbound states have been more elusive. Consequently, it is less clear how the unbound, sensing riboswitch refolds into the ligand binding-induced output state. The ligand recognition mechanisms of riboswitches are diverse, but we find that they share a common structural strategy in positioning their binding sites at the point of the RNA three-dimensional fold where the residues farthest from one another in sequence meet. We review how riboswitch folds adhere to this fundamental strategy and propose future research directions for understanding and harnessing their ability to specifically control gene expression.
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Affiliation(s)
- Christopher P Jones
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
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24
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Ketterer S, Gladis L, Kozica A, Meier M. Engineering and characterization of fluorogenic glycine riboswitches. Nucleic Acids Res 2016; 44:5983-92. [PMID: 27220466 PMCID: PMC4937332 DOI: 10.1093/nar/gkw465] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/15/2016] [Indexed: 11/20/2022] Open
Abstract
A set of 12 fluorogenic glycine riboswitches with different thermodynamic and kinetic response properties was engineered. For the design of functional riboswitches, a three-part RNA approach was applied based on the idea of linking a RNA sensor, transmitter and actuator part together. For the RNA sensor and actuator part, we used the tandem glycine aptamer structure from Bacillus subtillis, and fluorogenic aptamer Spinach, respectively. To achieve optimal signal transduction from the sensor to the actuator, a riboswitch library with variable transmitter was screened with a microfluidic large-scale integration chip. This allowed us to establish the complete thermodynamic binding profiles of the riboswitch library. Glycine dissociation constants of the 12 strong fluorescence response riboswitches varied between 99.7 and 570 μM. Furthermore, the kinetic glycine binding (kon), and dissociation (koff) rates, and corresponding energy barriers of the 10 strongest fluorescence response riboswitches were determined with the same chip platform. kon and koff were in the order of 10−3s−1 and 10−2s−1, respectively. Conclusively, we demonstrate that systematic screening of synthetic and natural linked RNA parts with microfluidic chip technology is an effective approach to rapidly generate fluorogenic metabolite riboswitches with a broad range of biophysical response properties.
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Affiliation(s)
- Simon Ketterer
- Microfluidic and Biological Engineering, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany Centre for Biological Signalling Studies-BIOSS, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
| | - Lukas Gladis
- Microfluidic and Biological Engineering, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany Centre for Biological Signalling Studies-BIOSS, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
| | - Adnan Kozica
- Microfluidic and Biological Engineering, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany Centre for Biological Signalling Studies-BIOSS, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
| | - Matthias Meier
- Microfluidic and Biological Engineering, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany Centre for Biological Signalling Studies-BIOSS, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
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25
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Machtel P, Bąkowska-Żywicka K, Żywicki M. Emerging applications of riboswitches - from antibacterial targets to molecular tools. J Appl Genet 2016; 57:531-541. [PMID: 27020791 PMCID: PMC5061826 DOI: 10.1007/s13353-016-0341-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/25/2016] [Accepted: 01/29/2016] [Indexed: 01/01/2023]
Abstract
The ability to precisely regulate gene expression is one of the most important features of the living cells as it enables the adaptation and survival in different environmental conditions. The majority of regulatory mechanisms involve protein action, however, multiple genes are controlled by nucleic acids. Among RNA-based regulators, the riboswitches present a large group of specific domains within messenger RNAs able to respond to small metabolites, tRNA, secondary messengers, ions, vitamins or amino acids. A simple, accurate, and efficient mechanism of action as well as easiness in handling and engineering make the riboswitches a potent practical tool in industry, medicine, pharmacy or environmental protection. Hereby, we summarize the current achievements and challenges in designing and practical employment of the riboswitch-based tools.
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Affiliation(s)
- Piotr Machtel
- Department of RNA Biology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznań, Poland
| | - Kamilla Bąkowska-Żywicka
- Department of RNA Biology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznań, Poland
| | - Marek Żywicki
- Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznań, Umultowska 89, 61-614, Poznań, Poland.
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Ligation of RNA Oligomers by the Schistosoma mansoni Hammerhead Ribozyme in Frozen Solution. J Mol Evol 2016; 82:81-92. [PMID: 26897022 DOI: 10.1007/s00239-016-9729-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 02/10/2016] [Indexed: 01/29/2023]
Abstract
The interstitial liquid phase within frozen aqueous solutions is an environment that minimizes RNA degradation and facilitates reactions that may have relevance to the RNA World hypothesis. Previous work has shown that frozen solutions support condensation of activated nucleotides into RNA oligomers, RNA ligation by the hairpin ribozyme, and RNA synthesis by a RNA polymerase ribozyme. In the current study, we examined the activity of a hammerhead ribozyme (HHR) in frozen solution. The Schistosoma mansoni hammerhead ribozyme, which predominantly cleaves RNA, can ligate its cleaved products (P1 and P2) with yields up to ~23 % in single turnover experiments at 25 °C in the presence of Mg(2+). Our studies show that this HHR ligates RNA oligomers in frozen solution in the absence of divalent cations. Citrate and other anions that exhibit strong ion-water affinity enhanced ligation. Yields up to 43 % were observed in one freeze-thaw cycle and a maximum of 60 % was obtained after several freeze-thaw cycles using wild-type P1 and P2. Truncated and mutated P1 substrates were ligated to P2 with yields of 14-24 % in one freeze-thaw cycle. A pool of P2 substrates with mixtures of all four bases at five positions were ligated with P1 in frozen solution. High-throughput sequencing indicated that 70 of the 1024 possible P2 sequences were represented in ligated products at 1000 or more read counts per million reads. The results indicate that the HHR can ligate a range of short RNA oligomers into an ensemble of diverse sequences in ice.
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Zhou LB, Zeng AP. Engineering a Lysine-ON Riboswitch for Metabolic Control of Lysine Production in Corynebacterium glutamicum. ACS Synth Biol 2015; 4:1335-40. [PMID: 26300047 DOI: 10.1021/acssynbio.5b00075] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Riboswitches are natural RNA elements that regulate gene expression by binding a ligand. Here, we demonstrate the possibility of altering a natural lysine-OFF riboswitch from Eschericia coli (ECRS) to a synthetic lysine-ON riboswitch and using it for metabolic control. To this end, a lysine-ON riboswitch library was constructed using tetA-based dual genetic selection. After screening the library, the functionality of the selected lysine-ON riboswitches was examined using a report gene, lacZ. Selected lysine-ON riboswitches were introduced into the lysE gene (encoding a lysine transport protein) of Corynebacterium glutamicum and used to achieve dynamic control of lysine transport in a recombinant lysine-producing strain, C. glutamicum LPECRS, which bears a deregulated aspartokinase and a lysine-OFF riboswitch for dynamic control of the enzyme citrate synthase. Batch fermentation results of the strains showed that the C. glutamicum LPECRS strain with an additional lysine-ON riboswitch for the control of lysE achieved a 21% increase in the yield of lysine compared to that of the C. glutamicum LPECRS strain and even a 89% increase in yield compared to that of the strain with deregulated aspartokinase. This work provides a useful approach to generate lysine-ON riboswitches for C. glutamicum metabolic engineering and demonstrates for the first time a synergetic effect of lysine-ON and -OFF riboswitches for improving lysine production in this industrially important microorganism. The approach can be used to dynamically control other genes and can be applied to other microorganisms.
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Affiliation(s)
- Li-Bang Zhou
- Institute of Bioprocess and
Biosystems Engineering, Hamburg University of Technology, Denickestrasse
15, D-21073 Hamburg, Germany
| | - An-Ping Zeng
- Institute of Bioprocess and
Biosystems Engineering, Hamburg University of Technology, Denickestrasse
15, D-21073 Hamburg, Germany
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28
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Peselis A, Gao A, Serganov A. Cooperativity, allostery and synergism in ligand binding to riboswitches. Biochimie 2015; 117:100-9. [PMID: 26143008 DOI: 10.1016/j.biochi.2015.06.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 06/29/2015] [Indexed: 01/04/2023]
Abstract
Recent progress in identification and characterization of novel types of non-coding RNAs has proven that RNAs carry out a variety of cellular functions ranging from scaffolding to gene expression control. In both prokaryotic and eukaryotic cells, several classes of non-coding RNAs control expression of dozens of genes in response to specific cues. One of the most interesting and outstanding questions in the RNA field is whether regulatory RNAs are capable of employing basic biological concepts, such as allostery and cooperativity, previously attributed to the function of proteins. Aside from regulatory RNAs that form complementary base pairing with their nucleic acid targets, several RNA classes modulate gene expression via molecular mechanisms which can be paralleled to protein-mediated regulation. Among these RNAs are riboswitches, metabolite-sensing non-coding regulatory elements that adopt intrinsic three-dimensional structures and specifically bind various small molecule ligands. These characteristics of riboswitches make them well-suited for complex regulatory responses observed in allosteric and cooperative protein systems. Here we present an overview of the biochemical, genetic, and structural studies of riboswitches with a major focus on complex regulatory mechanisms and biological principles utilized by riboswitches for such genetic modulation.
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Affiliation(s)
- Alla Peselis
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Ang Gao
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Alexander Serganov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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29
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Zhang J, Ferré-D'Amaré AR. Structure and mechanism of the T-box riboswitches. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 6:419-33. [PMID: 25959893 DOI: 10.1002/wrna.1285] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/19/2015] [Accepted: 03/25/2015] [Indexed: 01/11/2023]
Abstract
In most Gram-positive bacteria, including many clinically devastating pathogens from genera such as Bacillus, Clostridium, Listeria, and Staphylococcus, T-box riboswitches sense and regulate intracellular availability of amino acids through a multipartite messenger RNA (mRNA)-transfer RNA (tRNA) interaction. The T-box mRNA leaders respond to nutrient starvation by specifically binding cognate tRNAs and sensing whether the bound tRNA is aminoacylated, as a proxy for amino acid availability. Based on this readout, T-boxes direct a transcriptional or translational switch to control the expression of downstream genes involved in various aspects of amino acid metabolism: biosynthesis, transport, aminoacylation, transamidation, and so forth. Two decades after its discovery, the structural and mechanistic underpinnings of the T-box riboswitch were recently elucidated, producing a wealth of insights into how two structured RNAs can recognize each other with robust affinity and exquisite selectivity. The T-box paradigm exemplifies how natural noncoding RNAs can interact not just through sequence complementarity but can add molecular specificity by precisely juxtaposing RNA structural motifs, exploiting inherently flexible elements and the biophysical properties of post-transcriptional modifications, ultimately achieving a high degree of shape complementarity through mutually induced fit. The T-box also provides a proof-of-principle that compact RNA domains can recognize minute chemical changes (such as tRNA aminoacylation) on another RNA. The unveiling of the structure and mechanism of the T-box system thus expands our appreciation of the range of capabilities and modes of action of structured noncoding RNAs, and hints at the existence of networks of noncoding RNAs that communicate through both, structural and sequence specificity.
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Affiliation(s)
- Jinwei Zhang
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
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30
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From the RNA world to the RNA/protein world: contribution of some riboswitch-binding species? J Theor Biol 2015; 370:197-201. [PMID: 25571850 DOI: 10.1016/j.jtbi.2014.12.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 12/19/2014] [Accepted: 12/22/2014] [Indexed: 12/16/2022]
Abstract
Some amino acids and their formal derivatives, currently riboswitch-binding species, could have interacted with polyribonucletides in prebiotic environments, leading to the peptide formation. If the resulting compounds had led to a sustainable polymerization of amino acids and the new structures had catalytic activity, such would have been an important contribution to the transition from the RNA world to the RNA/Protein world.
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Abstract
The transition element molybdenum (Mo) is of primordial importance for biological systems, because it is required by enzymes catalyzing key reactions in the global carbon, sulfur, and nitrogen metabolism. To gain biological activity, Mo has to be complexed by a special cofactor. With the exception of bacterial nitrogenase, all Mo-dependent enzymes contain a unique pyranopterin-based cofactor coordinating a Mo atom at their catalytic site. Various types of reactions are catalyzed by Mo-enzymes in prokaryotes including oxygen atom transfer, sulfur or proton transfer, hydroxylation, or even nonredox reactions. Mo-enzymes are widespread in prokaryotes and many of them were likely present in the Last Universal Common Ancestor. To date, more than 50--mostly bacterial--Mo-enzymes are described in nature. In a few eubacteria and in many archaea, Mo is replaced by tungsten bound to the same unique pyranopterin. How Mo-cofactor is synthesized in bacteria is reviewed as well as the way until its insertion into apo-Mo-enzymes.
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32
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Zhang J, Ferré-D'Amaré AR. Direct evaluation of tRNA aminoacylation status by the T-box riboswitch using tRNA-mRNA stacking and steric readout. Mol Cell 2014; 55:148-55. [PMID: 24954903 DOI: 10.1016/j.molcel.2014.05.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 03/28/2014] [Accepted: 04/08/2014] [Indexed: 01/01/2023]
Abstract
T-boxes are gene-regulatory mRNA elements with which Gram-positive bacteria sense amino acid availability. T-boxes have two functional domains. Stem I recognizes the overall shape and anticodon of tRNA, while a 3' domain evaluates its aminoacylation status, overcoming an otherwise stable transcriptional terminator if the bound tRNA is uncharged. Although T-boxes are believed to evaluate tRNA charge status without using any proteins, this has not been demonstrated experimentally because of the instability of aminoacyl-tRNA. Using a simple method to prepare homogeneous aminoacyl-tRNA, we show that the Bacillus subtilis glyQS T-box functions independently of any tRNA-binding protein. Comparison of aminoacyl-tRNA analogs demonstrates that the T-box detects the molecular volume of tRNA 3'-substituents. Calorimetry and fluorescence lifetime analysis of labeled RNAs shows that the tRNA acceptor end coaxially stacks on a helix in the T-box 3' domain. This intimate intermolecular association, selective for uncharged tRNA, stabilizes the antiterminator conformation of the T-box.
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Affiliation(s)
- Jinwei Zhang
- National Heart, Lung and Blood Institute, 50 South Drive, MSC 8012, Bethesda, MD 20892-8012, USA
| | - Adrian R Ferré-D'Amaré
- National Heart, Lung and Blood Institute, 50 South Drive, MSC 8012, Bethesda, MD 20892-8012, USA.
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - James Hall
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
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34
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Mehdizadeh Aghdam E, Barzegar A, Hejazi MS. Evolutionary Origin and Conserved Structural Building Blocks of Riboswitches and Ribosomal RNAs: Riboswitches as Probable Target Sites for Aminoglycosides Interaction. Adv Pharm Bull 2014; 4:225-35. [PMID: 24754005 DOI: 10.5681/apb.2014.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 11/24/2013] [Accepted: 11/26/2013] [Indexed: 12/29/2022] Open
Abstract
PURPOSE Riboswitches, as noncoding RNA sequences, control gene expression through direct ligand binding. Sporadic reports on the structural relation of riboswitches with ribosomal RNAs (rRNA), raises an interest in possible similarity between riboswitches and rRNAs evolutionary origins. Since aminoglycoside antibiotics affect microbial cells through binding to functional sites of the bacterial rRNA, finding any conformational and functional relation between riboswitches/rRNAs is utmost important in both of medicinal and basic research. METHODS Analysis of the riboswitches structures were carried out using bioinformatics and computational tools. The possible functional similarity of riboswitches with rRNAs was evaluated based on the affinity of paromomycin antibiotic (targeting "A site" of 16S rRNA) to riboswitches via docking method. RESULTS There was high structural similarity between riboswitches and rRNAs, but not any particular sequence based similarity between them was found. The building blocks including "hairpin loop containing UUU", "peptidyl transferase center conserved hairpin A loop"," helix 45" and "S2 (G8) hairpin" as high identical rRNA motifs were detected in all kinds of riboswitches. Surprisingly, binding energies of paromomycin with different riboswitches are considerably better than the binding energy of paromomycin with "16S rRNA A site". Therefore the high affinity of paromomycin to bind riboswitches in comparison with rRNA "A site" suggests a new insight about riboswitches as possible targets for aminoglycoside antibiotics. CONCLUSION These findings are considered as a possible supporting evidence for evolutionary origin of riboswitches/rRNAs and also their role in the exertion of antibiotics effects to design new drugs based on the concomitant effects via rRNA/riboswitches.
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Affiliation(s)
- Elnaz Mehdizadeh Aghdam
- Drug Applied Research Center and Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Abolfazl Barzegar
- Research Institute for Fundamental Sciences (RIFS), University of Tabriz, Tabriz, Iran. ; The School of Advanced Biomedical Sciences (SABS), Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Saeid Hejazi
- Drug Applied Research Center and Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran. ; The School of Advanced Biomedical Sciences (SABS), Tabriz University of Medical Sciences, Tabriz, Iran
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35
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Saad NY, Stamatopoulou V, Brayé M, Drainas D, Stathopoulos C, Becker HD. Two-codon T-box riboswitch binding two tRNAs. Proc Natl Acad Sci U S A 2013; 110:12756-61. [PMID: 23858450 PMCID: PMC3732954 DOI: 10.1073/pnas.1304307110] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
T-box riboswitches control transcription of downstream genes through the tRNA-binding formation of terminator or antiterminator structures. Previously reported T-boxes were described as single-specificity riboswitches that can bind specific tRNA anticodons through codon-anticodon interactions with the nucleotide triplet of their specifier loop (SL). However, the possibility that T-boxes might exhibit specificity beyond a single tRNA had been overlooked. In Clostridium acetobutylicum, the T-box that regulates the operon for the essential tRNA-dependent transamidation pathway harbors a SL with two potential overlapping codon positions for tRNA(Asn) and tRNA(Glu). To test its specificity, we performed extensive mutagenic, biochemical, and chemical probing analyses. Surprisingly, both tRNAs can efficiently bind the SL in vitro and in vivo. The dual specificity of the T-box is allowed by a single base shift on the SL from one overlapping codon to the next. This feature allows the riboswitch to sense two tRNAs and balance the biosynthesis of two amino acids. Detailed genomic comparisons support our observations and suggest that "flexible" T-box riboswitches are widespread among bacteria, and, moreover, their specificity is dictated by the metabolic interconnection of the pathways under control. Taken together, our results support the notion of a genome-dependent codon ambiguity of the SLs. Furthermore, the existence of two overlapping codons imposes a unique example of tRNA-dependent regulation at the transcriptional level.
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MESH Headings
- Anticodon/chemistry
- Anticodon/genetics
- Anticodon/metabolism
- Asparagine/biosynthesis
- Asparagine/genetics
- Clostridium acetobutylicum/chemistry
- Clostridium acetobutylicum/genetics
- Clostridium acetobutylicum/metabolism
- Glutamic Acid/biosynthesis
- Glutamic Acid/genetics
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer, Asn/chemistry
- RNA, Transfer, Asn/genetics
- RNA, Transfer, Asn/metabolism
- RNA, Transfer, Glu/chemistry
- RNA, Transfer, Glu/genetics
- RNA, Transfer, Glu/metabolism
- Riboswitch/physiology
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Affiliation(s)
- Nizar Y. Saad
- Unité Mixte de Recherche 7156 Génétique Moléculaire, Génomique, Microbiologie, Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg, France
- Unité Propre de Recherche Architecture et Réactivité de l’ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, F-67084 Strasbourg, France; and
| | | | - Mélanie Brayé
- Unité Propre de Recherche Architecture et Réactivité de l’ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, F-67084 Strasbourg, France; and
| | - Denis Drainas
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | | | - Hubert Dominique Becker
- Unité Mixte de Recherche 7156 Génétique Moléculaire, Génomique, Microbiologie, Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg, France
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Wilson-Mitchell SN, Grundy FJ, Henkin TM. Analysis of lysine recognition and specificity of the Bacillus subtilis L box riboswitch. Nucleic Acids Res 2012; 40:5706-17. [PMID: 22416067 PMCID: PMC3384330 DOI: 10.1093/nar/gks212] [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] [Indexed: 11/12/2022] Open
Abstract
The ever-changing environment of a bacterial cell requires sophisticated mechanisms to adjust gene expression in response to changes in nutrient availability. L box riboswitch RNAs regulate gene expression in response to cellular lysine (lys) concentrations in the absence of additional regulatory factors. In Bacillus subtilis, binding of lysine (lys) to the L box RNA causes premature transcription termination in the leader region upstream of the lysC coding sequence. To date, little is known about the specific RNA-lys interactions required for transcription termination. In this study, we characterize features of the B. subtilis lysC leader RNA responsible for lys specificity, and structural elements of the lys molecule required for recognition. The wild-type lysC leader RNA can recognize and discriminate between lys and lys analogs. We identified leader RNA variants with mutations in the lys-binding pocket that exhibit changes in the specificity of ligand recognition. These data demonstrate that lysC leader RNA specificity is the result of recognition of ligand features through a series of distinct interactions between lys and nucleotides that comprise the lys-binding pocket, and provide insight into the molecular mechanisms employed by L box riboswitch RNAs to bind and recognize lys.
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37
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Abstract
Among the nine classes of ribozymes that have been experimentally validated to date is the metabolite-responsive self-cleaving ribozyme called glmS. This RNA is almost exclusively located in the 5'-untranslated region of bacterial mRNAs that code for the production of GlmS proteins, which catalyze the synthesis of the aminosugar glucosamine-6-phosphate (GlcN6P). Each glmS ribozyme forms a conserved catalytic core that selectively binds GlcN6P and uses this metabolite as a cofactor to promote ribozyme self-cleavage. Metabolite-induced self-cleavage results in down-regulation of glmS gene expression, and thus the ribozyme functions as a key riboswitch component to permit feedback regulation of GlcN6P levels. Representatives of glmS ribozymes also serve as excellent experimental models to elucidate how RNAs fold to recognize small molecule ligands and promote chemical transformations.
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Affiliation(s)
- Phillip J McCown
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
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38
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Liberman JA, Wedekind JE. Riboswitch structure in the ligand-free state. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 3:369-84. [PMID: 21957061 DOI: 10.1002/wrna.114] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Molecular investigations of riboswitches bound to small-molecule effectors have produced a wealth of information on how these molecules achieve high affinity and specificity for a target ligand. X-ray crystal structures have been determined for the ligand-free state for representatives of the preQ₁-I, S-adenosylmethionine I, lysine, and glycine aptamer classes. These structures in conjunction with complimentary techniques, such as in-line probing, NMR spectroscopy, Förster resonance energy transfer, small-angle scattering, and computational simulations, have demonstrated that riboswitches adopt multiple conformations in the absence of ligand. Despite a number of investigations that support ligand-dependent folding, mounting evidence suggests that free-state riboswitches interact with their effectors in the sub-populations of largely prefolded states as embodied by the principle of conformational selection, which has been documented extensively for protein-mediated ligand interactions. Fundamental riboswitch investigations of the bound and free states have advanced our understanding of RNA folding, ligand recognition, and how these factors culminate in communication between an aptamer and its expression platform. An understanding of these topics is essential to comprehend riboswitch gene regulation at the molecular level, which has already provided a basis to understand the mechanism of action of natural antimicrobials.
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Affiliation(s)
- Joseph A Liberman
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Strauss B, Nierth A, Singer M, Jäschke A. Direct structural analysis of modified RNA by fluorescent in-line probing. Nucleic Acids Res 2011; 40:861-70. [PMID: 21917852 PMCID: PMC3258135 DOI: 10.1093/nar/gkr733] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chemical probing is a common method for the structural characterization of RNA. Typically, RNA is radioactively end-labelled, subjected to probing conditions, and the cleavage fragment pattern is analysed by gel electrophoresis. In recent years, many chemical modifications, like fluorophores, were introduced into RNA, but methods are lacking that detect the influence of the modification on the RNA structure with single-nucleotide resolution. Here, we first demonstrate that a 5′-terminal 32P label can be replaced by a dye label for in-line probing of riboswitch RNAs. Next, we show that small, highly structured FRET-labelled Diels–Alderase ribozymes can be directly probed, using the internal or terminal FRET dyes as reporters. The probing patterns indeed reveal whether or not the attachment of the dyes influences the structure. The existence of two dye labels in typical FRET constructs is found to be beneficial, as ‘duplexing’ allows observation of the complete RNA on a single gel. Structural information can be derived from the probing gels by deconvolution of the superimposed band patterns. Finally, we use fluorescent in-line probing to experimentally validate the structural consequences of photocaging, unambiguously demonstrating the intentional destruction of selected elements of secondary or tertiary structure.
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Affiliation(s)
- Benjamin Strauss
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany
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40
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Abstract
The intergenic regions in bacterial genomes can contain regulatory leader sequences and small RNAs (sRNAs), which both serve to modulate gene expression. Computational analyses have predicted the presence of hundreds of these noncoding regulatory RNAs in Escherichia coli; however, only about 80 have been experimentally validated. By applying a deep-sequencing approach, we detected and quantified the vast majority of the previously validated regulatory elements and identified 10 new sRNAs and nine new regulatory leader sequences in the intergenic regions of E. coli. Half of the newly discovered sRNAs displayed enhanced stability in the presence of the RNA-binding protein Hfq, which is vital to the function of many of the known E. coli sRNAs. Whereas previous methods have often relied on phylogenetic conservation to identify regulatory leader sequences, only five of the newly discovered E. coli leader sequences were present in the genomes of other enteric species. For those newly identified regulatory elements having orthologs in Salmonella, evolutionary analyses showed that these regions encoded new noncoding elements rather than small, unannotated protein-coding transcripts. In addition to discovering new noncoding regulatory elements, we validated 53 sRNAs that were previously predicted but never detected and showed that the presence, within intergenic regions, of σ(70) promoters and sequences with compensatory mutations that maintain stable RNA secondary structures across related species is a good predictor of novel sRNAs.
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Magalon A, Fedor JG, Walburger A, Weiner JH. Molybdenum enzymes in bacteria and their maturation. Coord Chem Rev 2011. [DOI: 10.1016/j.ccr.2010.12.031] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Base ionization and ligand binding: how small ribozymes and riboswitches gain a foothold in a protein world. Curr Opin Struct Biol 2011; 21:327-34. [PMID: 21530235 DOI: 10.1016/j.sbi.2011.03.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 11/21/2022]
Abstract
Genome sequencing has produced thousands of nonprotein coding (nc)RNA sequences including new ribozymes and riboswitches. Such RNAs are notable for their extraordinary functionality, which entails exquisite folding that culminates in biocatalytic or ligand-binding capabilities. Here we discuss advances in relating ncRNA form to function with an emphasis on base pK(a) shifting by the hairpin and hepatitis delta virus ribozymes. We then describe ligand binding by the two smallest riboswitches, which target preQ(1) and S-adenosyl-(l)-homocysteine, followed by an analysis of a second-messenger riboswitch that binds cyclic-di-GMP. Each riboswitch is then compared to a protein that binds the same ligand to contrast binding properties. The results showcase the breadth of functionality attainable from ncRNAs, as well as molecular features notable for antibacterial design.
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Zhang Q, Kang M, Peterson RD, Feigon J. Comparison of solution and crystal structures of preQ1 riboswitch reveals calcium-induced changes in conformation and dynamics. J Am Chem Soc 2011; 133:5190-3. [PMID: 21410253 PMCID: PMC3085290 DOI: 10.1021/ja111769g] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
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Riboswitches regulate gene expression via specific recognition of cognate metabolites by their aptamer domains, which fold into stable conformations upon ligand binding. However, the recently reported solution and crystal structures of the Bacillus subtilis preQ1 riboswitch aptamer show small but significant differences, suggesting that there may be conformational heterogeneity in the ligand-bound state. We present a structural and dynamic characterization of this aptamer by solution NMR spectroscopy. The aptamer−preQ1 complex is intrinsically flexible in solution, with two regions that undergo motions on different time scales. Three residues move in concert on the micro-to-millisecond time scale and may serve as the lid of the preQ1-binding pocket. Several Ca2+ ions are present in the crystal structure, one of which binds with an affinity of 47 ± 2 μM in solution to a site that is formed only upon ligand binding. Addition of Ca2+ to the aptamer−preQ1 complex in solution results in conformational changes that account for the differences between the solution and crystal structures. Remarkably, the Ca2+ ions present in the crystal structure, which were proposed to be important for folding and ligand recognition, are not required for either in solution.
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Affiliation(s)
- Qi Zhang
- Department of Chemistry and Biochemistry , University of California, Los Angeles, California 90095-1569, USA
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44
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Huang L, Serganov A, Patel DJ. Structural insights into ligand recognition by a sensing domain of the cooperative glycine riboswitch. Mol Cell 2011; 40:774-86. [PMID: 21145485 DOI: 10.1016/j.molcel.2010.11.026] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 08/05/2010] [Accepted: 09/24/2010] [Indexed: 01/11/2023]
Abstract
Glycine riboswitches regulate gene expression by feedback modulation in response to cooperative binding to glycine. Here, we report on crystal structures of the second glycine-sensing domain from the Vibrio cholerae riboswitch in the ligand-bound and unbound states. This domain adopts a three-helical fold that centers on a three-way junction and accommodates glycine within a bulge-containing binding pocket above the junction. Glycine recognition is facilitated by a pair of bound Mg(2+) cations and governed by specific interactions and shape complementarity with the pocket. A conserved adenine extrudes from the binding pocket and intercalates into the junction implying that glycine binding in the context of the complete riboswitch could impact on gene expression by stabilizing the riboswitch junction and regulatory P1 helix. Analysis of riboswitch interactions in the crystal and footprinting experiments indicates that adjacent glycine-sensing modules of the riboswitch could form specific interdomain interactions, thereby potentially contributing to the cooperative response.
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Affiliation(s)
- Lili Huang
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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45
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Erion TV, Strobel SA. Identification of a tertiary interaction important for cooperative ligand binding by the glycine riboswitch. RNA (NEW YORK, N.Y.) 2011; 17:74-84. [PMID: 21098652 PMCID: PMC3004068 DOI: 10.1261/rna.2271511] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 10/27/2010] [Indexed: 05/21/2023]
Abstract
The glycine riboswitch has a tandem dual aptamer configuration, where each aptamer is a separate ligand-binding domain, but the aptamers function together to bind glycine cooperatively. We sought to understand the molecular basis of glycine riboswitch cooperativity by comparing sites of tertiary contacts in a series of cooperative and noncooperative glycine riboswitch mutants using hydroxyl radical footprinting, in-line probing, and native gel-shift studies. The results illustrate the importance of a direct or indirect interaction between the P3b hairpin of aptamer 2 and the P1 helix of aptamer 1 in cooperative glycine binding. Furthermore, our data support a model in which glycine binding is sequential; where the binding of glycine to the second aptamer allows tertiary interactions to be made that facilitate binding of a second glycine molecule to the first aptamer. These results provide insight into cooperative ligand binding in RNA macromolecules.
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Affiliation(s)
- Thanh V Erion
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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46
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Yang X, Bing T, Mei H, Fang C, Cao Z, Shangguan D. Characterization and application of a DNA aptamer binding to L-tryptophan. Analyst 2010; 136:577-85. [PMID: 21076782 DOI: 10.1039/c0an00550a] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
DNA aptamers for specific recognition of L-tryptophan have been evolved by a SELEX (systematic evolution of ligands by exponential enrichment) technique. Truncation-mutation experiments suggest that a 34-mer sequence, Trp3a-1, possesses the strongest binding ability to L-tryptophan. Trp3a-1 is predicted to adopt a loop-stem secondary structure, in which the loop may further fold into a binding pocket for L-tryptophan with the help of the stem. The specificity investigation shows that Trp3a-1 strongly binds to L-tryptophan, has almost no binding to other amino acids, and weakly binds to some tryptophan analogs and peptides containing the L-tryptophan residue. The binding of Trp3a-1 to L-tryptophan is mainly contributed to by hydrogen bonds and precise stacking formed between the binding pocket of Trp3a-1 and all groups on L-tryptophan. This aptamer has also been proved to be an effective ligand for the chiral separation of D/L-tryptophan. L-tryptophan and its derivatives are known to play important biological roles; this aptamer ligand could be used as a tool for the analysis of tryptophan and other related studies.
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Affiliation(s)
- Xiaojuan Yang
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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47
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SAM recognition and conformational switching mechanism in the Bacillus subtilis yitJ S box/SAM-I riboswitch. J Mol Biol 2010; 404:803-18. [PMID: 20951706 DOI: 10.1016/j.jmb.2010.09.059] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 09/21/2010] [Accepted: 09/27/2010] [Indexed: 01/09/2023]
Abstract
S-box (SAM-I) riboswitches are a widespread class of riboswitches involved in the regulation of sulfur metabolism in Gram-positive bacteria. We report here the 3.0-Å crystal structure of the aptamer domain of the Bacillus subtilis yitJ S-box (SAM-I) riboswitch bound to S-adenosyl-L-methionine (SAM). The RNA folds into two sets of helical stacks spatially arranged by tertiary interactions including a K-turn and a pseudoknot at a four-way junction. The tertiary structure is further stabilized by metal coordination, extensive ribose zipper interactions, and SAM-mediated tertiary interactions. Despite structural differences in the peripheral regions, the SAM-binding core of the B. subtilis yitJ riboswitch is virtually superimposable with the previously determined Thermoanaerobacter tengcongensis yitJ riboswitch structure, suggesting that a highly conserved ligand-recognition mechanism is utilized by all S-box riboswitches. SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) chemical probing analysis further revealed that the alternative base-pairing element in the expression platform controls the conformational switching process. In the absence of SAM, the apo yitJ aptamer domain folds predominantly into a pre-binding conformation that resembles, but is not identical with, the SAM-bound state. We propose that SAM enters the ligand-binding site through the "J1/2-J3/4" gate and "locks" down the SAM-bound conformation through an induced-fit mechanism. Temperature-dependent SHAPE revealed that the tertiary interaction-stabilized SAM-binding core is extremely stable, likely due to the cooperative RNA folding behavior. Mutational studies revealed that certain modifications in the SAM-binding region result in loss of SAM binding and constitutive termination, which suggests that these mutations lock the RNA into a form that resembles the SAM-bound form in the absence of SAM.
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48
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Blanchard SC, Cooperman BS, Wilson DN. Probing translation with small-molecule inhibitors. ACTA ACUST UNITED AC 2010; 17:633-45. [PMID: 20609413 DOI: 10.1016/j.chembiol.2010.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/14/2010] [Accepted: 06/07/2010] [Indexed: 10/19/2022]
Abstract
The translational apparatus of the bacterial cell remains one of the principal targets of antibiotics for the clinical treatment of infection worldwide. Since the introduction of specific translation inhibitors into clinical practice in the late 1940s, intense efforts have been made to understand their precise mechanisms of action. Such research has often revealed significant and sometimes unexpected insights into many fundamental aspects of the translation mechanism. Central to progress in this area, high-resolution crystal structures of the bacterial ribosome identifying the sites of antibiotic binding are now available, which, together with recent developments in single-molecule and fast-kinetic approaches, provide an integrated view of the dynamic translation process. Assays employing these approaches and focusing on specific steps of the overall translation process are amenable for drug screening. Such assays, coupled with structural studies, have the potential not only to accelerate the discovery of novel and effective antimicrobial agents, but also to refine our understanding of the mechanisms of translation. Antibiotics often stabilize specific functional states of the ribosome and therefore allow distinct translation steps to be dissected in molecular detail.
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Affiliation(s)
- Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
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49
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Molina-Quintero LR, Lucas-Elío P, Sanchez-Amat A. Regulation of the Marinomonas mediterranea antimicrobial protein lysine oxidase by L-lysine and the sensor histidine kinase PpoS. Appl Environ Microbiol 2010; 76:6141-9. [PMID: 20656878 PMCID: PMC2937512 DOI: 10.1128/aem.00690-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 07/10/2010] [Indexed: 11/20/2022] Open
Abstract
Some Gram-negative bacteria express a novel enzyme with lysine-epsilon-oxidase (LOD) activity (EC 1.4.3.20). The oxidation of l-Lys generates, among other products, hydrogen peroxide, which confers antimicrobial properties to this kind of enzyme and has been shown to be involved in cell death during biofilm development and differentiation. In addition to LOD, the melanogenic marine bacterium Marinomonas mediterranea, which forms part of the microbiota of the marine plant Posidonia oceanica, expresses two other oxidases of biotechnological interest, a multicopper oxidase, PpoA, with laccase activity and a tyrosinase named PpoB, which is responsible for melanin synthesis. By using both lacZ fusions with the lodAB promoter and quantitative reverse transcription-PCR (qRT-PCR), this study shows that the hybrid sensor histidine kinase PpoS regulates LOD activity at the transcriptional level. Although PpoS also regulates PpoA and PpoB, in this case, the regulatory effect cannot be attributed only to a transcriptional regulation. Further studies indicate that LOD activity is induced at the posttranscriptional level by l-Lys as well as by two structurally similar compounds, l-Arg and meso-2,6-diaminopimelic acid (DAP), neither of which is a substrate of the enzyme. The inducing effect of these compounds is specific for LOD activity since PpoA and PpoB are not affected by them. This study offers, for the first time, insights into the mechanisms regulating the synthesis of the antimicrobial protein lysine-epsilon-oxidase in M. mediterranea, which could be important in the microbial colonization of the seagrass P. oceanica.
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Affiliation(s)
| | - Patricia Lucas-Elío
- Department of Genetics and Microbiology, University of Murcia, 30100 Murcia, Spain
| | - Antonio Sanchez-Amat
- Department of Genetics and Microbiology, University of Murcia, 30100 Murcia, Spain
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50
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Lioliou E, Romilly C, Romby P, Fechter P. RNA-mediated regulation in bacteria: from natural to artificial systems. N Biotechnol 2010; 27:222-35. [PMID: 20211281 DOI: 10.1016/j.nbt.2010.03.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Bacteria use various means of RNA-mediated gene regulation. Regulatory RNAs include mRNA leaders that affect expression in cis or in trans, non-coding RNAs that trap regulatory proteins or interact with one or multiple target mRNAs, and RNAs that protect the bacteria against foreign and invasive DNA. The aim of this review is to outline the basic principles of bacterial RNA-mediated regulation, with a special focus on both cis-acting regulatory regions of mRNAs and antisense RNAs (asRNAs), and to give a brief overview of selected examples of RNA-based technology that have paved the way for biotechnological applications.
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Affiliation(s)
- Efthimia Lioliou
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 15 rue René Descartes, Strasbourg cedex, France
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