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Kishimoto T, Nishimura K, Morishita K, Fukuda A, Miyamae Y, Kumagai Y, Sumaru K, Nakanishi M, Hisatake K, Sano M. An engineered ligand-responsive Csy4 endoribonuclease controls transgene expression from Sendai virus vectors. J Biol Eng 2024; 18:9. [PMID: 38229076 DOI: 10.1186/s13036-024-00404-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
BACKGROUND Viral vectors are attractive gene delivery vehicles because of their broad tropism, high transduction efficiency, and durable expression. With no risk of integration into the host genome, the vectors developed from RNA viruses such as Sendai virus (SeV) are especially promising. However, RNA-based vectors have limited applicability because they lack a convenient method to control transgene expression by an external inducer. RESULTS We engineered a Csy4 switch in Sendai virus-based vectors by combining Csy4 endoribonuclease with mutant FKBP12 (DD: destabilizing domain) that becomes stabilized when a small chemical Shield1 is supplied. In this Shield1-responsive Csy4 (SrC) switch, Shield1 increases Csy4 fused with DD (DD-Csy4), which then cleaves and downregulates the transgene mRNA containing the Csy4 recognition sequence (Csy4RS). Moreover, when Csy4RS is inserted in the viral L gene, the SrC switch suppresses replication and transcription of the SeV vector in infected cells in a Shield1-dependent manner, thus enabling complete elimination of the vector from the cells. By temporally controlling BRN4 expression, a BRN4-expressing SeV vector equipped with the SrC switch achieves efficient, stepwise differentiation of embryonic stem cells into neural stem cells, and then into astrocytes. CONCLUSION SeV-based vectors with the SrC switch should find wide applications in stem cell research, regenerative medicine, and gene therapy, especially when precise control of reprogramming factor expression is desirable.
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Grants
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
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Affiliation(s)
- Takumi Kishimoto
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
- Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Ken Nishimura
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
| | - Kana Morishita
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Aya Fukuda
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
| | - Yusaku Miyamae
- Institute of Life and Environment Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yutaro Kumagai
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Kimio Sumaru
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Mahito Nakanishi
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
- TOKIWA-Bio, Inc, 2-1-6 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - Koji Hisatake
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
| | - Masayuki Sano
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
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Su Z, Li T, Wu D, Wu Y, Li G. Recent Progress on Single-Molecule Detection Technologies for Food Safety. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:458-469. [PMID: 34985271 DOI: 10.1021/acs.jafc.1c06808] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Rapid and sensitive detection technologies for food contaminants play vital roles in food safety. Due to the complexity of the food matrix and the trace amount distribution, traditional methods often suffer from unsatisfying accuracy, sensitivity, or specificity. In past decades, single-molecule detection (SMD) has emerged as a way to realize the rapid and ultrasensitive measurement with low sample consumption, showing a great potential in food contaminants detection. For instance, based on the nanopore technique, simple and effective methods for single-molecule analysis of food contaminants have been developed. To our knowledge, there has been a rare review that focuses on SMD techniques for food safety. The present review attempts to cover some typical SMD methods in food safety, including electrochemistry, optical spectrum, and atom force microscopy. Then, recent applications of these techniques for detecting food contaminants such as biotoxins, pesticides, heavy metals, and illegal additives are reviewed. Finally, existing research challenges and future trends of SMD in food safety are also tentatively proposed.
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Affiliation(s)
- Zhuoqun Su
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Tong Li
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Di Wu
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Yongning Wu
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
- NHC Key Laboratory of Food Safety Risk Assessment, Food Safety Research Unit (2019RU014) of Chinese Academy of Medical Science, China National Center for Food Safety Risk Assessment, Beijing 100021, China
| | - Guoliang Li
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
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3
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Weng R, Lou S, Li L, Zhang Y, Qiu J, Su X, Qian Y, Walter NG. Single-Molecule Kinetic Fingerprinting for the Ultrasensitive Detection of Small Molecules with Aptasensors. Anal Chem 2019; 91:1424-1431. [PMID: 30562003 DOI: 10.1021/acs.analchem.8b04145] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aptamers have emerged as promising molecular tools for small-molecule analyte sensing. However, the performance of such aptasensors is generally limited by leakage since it has been difficult to completely suppress signal in the absence of analyte, resulting in a compromise between sensitivity and specificity. Here, we describe a methodology for the ultrasensitive detection of analytes combining aptasensors with single-molecule kinetic fingerprinting. A short, fluorescently labeled DNA probe is utilized to detect the structural changes upon ligand binding to the designed hairpin-shaped aptasensor probe. The Poisson statistics of binding and dissociation events of the DNA probe to single surface-immobilized aptasensor molecules is monitored by total internal reflection fluorescence microscopy, permitting the high-accuracy discrimination of the ligand bound and ligand-free states, resulting in zero background. The programmable dynamics of the hairpin enables fine-tuning of the hybridization kinetics of the fluorescent probe, rendering the acquisition time sufficiently flexible to optimize discrimination. Remarkable detection limits are achieved for a diverse set of analytes when spiked into chicken meat extract: the nucleotide adenosine (0.3 pM), the insecticide acetamiprid (0.35 pM), and the dioxin-like toxin PCB-77 (0.72 pM), which is superior to recently reported aptasensors. Our generalizable method significantly improves the performance of aptasensors, with the potential to extend to other molecular biomarkers.
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Affiliation(s)
- Rui Weng
- Key Laboratory of Agro-food Safety and Quality of Ministry of Agriculture and Rural Affairs, Institute of Quality Standards and Testing Technology for Agro-Products , Chinese Academy of Agricultural Sciences , Beijing 100081 , China
| | - Shengting Lou
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology , Beijing University of Chemical Technology , Beijing 100029 , China
| | - Lidan Li
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology , Beijing University of Chemical Technology , Beijing 100029 , China
| | - Yi Zhang
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology , Beijing University of Chemical Technology , Beijing 100029 , China
| | - Jing Qiu
- Key Laboratory of Agro-food Safety and Quality of Ministry of Agriculture and Rural Affairs, Institute of Quality Standards and Testing Technology for Agro-Products , Chinese Academy of Agricultural Sciences , Beijing 100081 , China
| | - Xin Su
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology , Beijing University of Chemical Technology , Beijing 100029 , China
| | - Yongzhong Qian
- Key Laboratory of Agro-food Safety and Quality of Ministry of Agriculture and Rural Affairs, Institute of Quality Standards and Testing Technology for Agro-Products , Chinese Academy of Agricultural Sciences , Beijing 100081 , China
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
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4
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Ray S, Widom JR, Walter NG. Life under the Microscope: Single-Molecule Fluorescence Highlights the RNA World. Chem Rev 2018; 118:4120-4155. [PMID: 29363314 PMCID: PMC5918467 DOI: 10.1021/acs.chemrev.7b00519] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The emergence of single-molecule (SM) fluorescence techniques has opened up a vast new toolbox for exploring the molecular basis of life. The ability to monitor individual biomolecules in real time enables complex, dynamic folding pathways to be interrogated without the averaging effect of ensemble measurements. In parallel, modern biology has been revolutionized by our emerging understanding of the many functions of RNA. In this comprehensive review, we survey SM fluorescence approaches and discuss how the application of these tools to RNA and RNA-containing macromolecular complexes in vitro has yielded significant insights into the underlying biology. Topics covered include the three-dimensional folding landscapes of a plethora of isolated RNA molecules, their assembly and interactions in RNA-protein complexes, and the relation of these properties to their biological functions. In all of these examples, the use of SM fluorescence methods has revealed critical information beyond the reach of ensemble averages.
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Affiliation(s)
| | | | - Nils G. Walter
- Department of Chemistry, Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA
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5
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Börner R, Kowerko D, Miserachs HG, Schaffer MF, Sigel RK. Metal ion induced heterogeneity in RNA folding studied by smFRET. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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6
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Rinaldi AJ, Lund PE, Blanco MR, Walter NG. The Shine-Dalgarno sequence of riboswitch-regulated single mRNAs shows ligand-dependent accessibility bursts. Nat Commun 2016; 7:8976. [PMID: 26781350 PMCID: PMC4735710 DOI: 10.1038/ncomms9976] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 10/21/2015] [Indexed: 01/20/2023] Open
Abstract
In response to intracellular signals in Gram-negative bacteria, translational riboswitches—commonly embedded in messenger RNAs (mRNAs)—regulate gene expression through inhibition of translation initiation. It is generally thought that this regulation originates from occlusion of the Shine-Dalgarno (SD) sequence upon ligand binding; however, little direct evidence exists. Here we develop Single Molecule Kinetic Analysis of RNA Transient Structure (SiM-KARTS) to investigate the ligand-dependent accessibility of the SD sequence of an mRNA hosting the 7-aminomethyl-7-deazaguanine (preQ1)-sensing riboswitch. Spike train analysis reveals that individual mRNA molecules alternate between two conformational states, distinguished by ‘bursts' of probe binding associated with increased SD sequence accessibility. Addition of preQ1 decreases the lifetime of the SD's high-accessibility (bursting) state and prolongs the time between bursts. In addition, ligand-jump experiments reveal imperfect riboswitching of single mRNA molecules. Such complex ligand sensing by individual mRNA molecules rationalizes the nuanced ligand response observed during bulk mRNA translation. In response to intracellular signals, bacterial translational riboswitches embedded in mRNAs can regulate gene expression through inhibition of translation initiation. Here, the authors describe SiM-KARTS, a novel approach for detecting changes in the structure of single RNA molecules in response to a ligand.
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Affiliation(s)
- Arlie J Rinaldi
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Paul E Lund
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.,Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Mario R Blanco
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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7
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Rinaldi AJ, Suddala KC, Walter NG. Native purification and labeling of RNA for single molecule fluorescence studies. Methods Mol Biol 2015; 1240:63-95. [PMID: 25352138 DOI: 10.1007/978-1-4939-1896-6_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The recent discovery that non-coding RNAs are considerably more abundant and serve a much wider range of critical cellular functions than recognized over previous decades of research into molecular biology has sparked a renewed interest in the study of structure-function relationships of RNA. To perform their functions in the cell, RNAs must dominantly adopt their native conformations, avoiding deep, non-productive kinetic traps that may exist along a frustrated (rugged) folding free energy landscape. Intracellularly, RNAs are synthesized by RNA polymerase and fold co-transcriptionally starting from the 5' end, sometimes with the aid of protein chaperones. By contrast, in the laboratory RNAs are commonly generated by in vitro transcription or chemical synthesis, followed by purification in a manner that includes the use of high concentrations of urea, heat and UV light (for detection), resulting in the denaturation and subsequent refolding of the entire RNA. Recent studies into the nature of heterogeneous RNA populations resulting from this process have underscored the need for non-denaturing (native) purification methods that maintain the co-transcriptional fold of an RNA. Here, we present protocols for the native purification of an RNA after its in vitro transcription and for fluorophore and biotin labeling methods designed to preserve its native conformation for use in single molecule fluorescence resonance energy transfer (smFRET) inquiries into its structure and function. Finally, we present methods for taking smFRET data and for analyzing them, as well as a description of plausible overall preparation schemes for the plethora of non-coding RNAs.
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Affiliation(s)
- Arlie J Rinaldi
- W. M. Keck Science Center, The Claremont Colleges, Claremont, CA, 91711, USA
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8
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Trausch JJ, Batey RT. Design of Modular “Plug-and-Play” Expression Platforms Derived from Natural Riboswitches for Engineering Novel Genetically Encodable RNA Regulatory Devices. Methods Enzymol 2015; 550:41-71. [DOI: 10.1016/bs.mie.2014.10.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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9
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Widom JR, Dhakal S, Heinicke LA, Walter NG. Single-molecule tools for enzymology, structural biology, systems biology and nanotechnology: an update. Arch Toxicol 2014; 88:1965-85. [PMID: 25212907 PMCID: PMC4615698 DOI: 10.1007/s00204-014-1357-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 08/28/2014] [Indexed: 12/22/2022]
Abstract
Toxicology is the highly interdisciplinary field studying the adverse effects of chemicals on living organisms. It requires sensitive tools to detect such effects. After their initial implementation during the 1990s, single-molecule fluorescence detection tools were quickly recognized for their potential to contribute greatly to many different areas of scientific inquiry. In the intervening time, technical advances in the field have generated ever-improving spatial and temporal resolution and have enabled the application of single-molecule fluorescence to increasingly complex systems, such as live cells. In this review, we give an overview of the optical components necessary to implement the most common versions of single-molecule fluorescence detection. We then discuss current applications to enzymology and structural studies, systems biology, and nanotechnology, presenting the technical considerations that are unique to each area of study, along with noteworthy recent results. We also highlight future directions that have the potential to revolutionize these areas of study by further exploiting the capabilities of single-molecule fluorescence microscopy.
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Affiliation(s)
- Julia R Widom
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI, 48109-1055, USA
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10
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Wang ZY, Ren ZN, Liu FZ, Liu SY, Wang ZX, Zhu XL. Fabrication of stable and reversible DNA–RNA hammerhead ribozyme on a solid surface. RSC Adv 2014. [DOI: 10.1039/c4ra07170k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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11
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Frommer J, Appel B, Müller S. Ribozymes that can be regulated by external stimuli. Curr Opin Biotechnol 2014; 31:35-41. [PMID: 25146171 DOI: 10.1016/j.copbio.2014.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/30/2014] [Indexed: 12/20/2022]
Abstract
Ribozymes have been known for about 30 years, and nowadays are understood well enough to be turned into useful tools for a number of applications in vitro and in vivo. Allosteric ribozymes switch on and off their activity in response to a specific chemical (ligand) or physical (temperature, light) signal. The possibility of controlling ribozyme activity by external stimuli is of particular relevance for applications in different fields, such as environmental and medicinal diagnostics, molecular computing, control of gene expression and others. Herein, we review recent advances and describe selected examples of addressable ribozymes.
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Affiliation(s)
- Jennifer Frommer
- Ernst Moritz Arndt University Greifswald, Institute for Biochemistry, Felix Hausdorff Str. 4, D-17487 Greifswald, Germany
| | - Bettina Appel
- Ernst Moritz Arndt University Greifswald, Institute for Biochemistry, Felix Hausdorff Str. 4, D-17487 Greifswald, Germany
| | - Sabine Müller
- Ernst Moritz Arndt University Greifswald, Institute for Biochemistry, Felix Hausdorff Str. 4, D-17487 Greifswald, Germany.
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12
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Sett A, Das S, Bora U. Functional nucleic-acid-based sensors for environmental monitoring. Appl Biochem Biotechnol 2014; 174:1073-91. [PMID: 24903959 DOI: 10.1007/s12010-014-0990-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 05/19/2014] [Indexed: 01/16/2023]
Abstract
Efforts to replace conventional chromatographic methods for environmental monitoring with cheaper and easy to use biosensors for precise detection and estimation of hazardous environmental toxicants, water or air borne pathogens as well as various other chemicals and biologics are gaining momentum. Out of the various types of biosensors classified according to their bio-recognition principle, nucleic-acid-based sensors have shown high potential in terms of cost, sensitivity, and specificity. The discovery of catalytic activities of RNA (ribozymes) and DNA (DNAzymes) which could be triggered by divalent metallic ions paved the way for their extensive use in detection of heavy metal contaminants in environment. This was followed with the invention of small oligonucleotide sequences called aptamers which can fold into specific 3D conformation under suitable conditions after binding to target molecules. Due to their high affinity, specificity, reusability, stability, and non-immunogenicity to vast array of targets like small and macromolecules from organic, inorganic, and biological origin, they can often be exploited as sensors in industrial waste management, pollution control, and environmental toxicology. Further, rational combination of the catalytic activity of DNAzymes and RNAzymes along with the sequence-specific binding ability of aptamers have given rise to the most advanced form of functional nucleic-acid-based sensors called aptazymes. Functional nucleic-acid-based sensors (FNASs) can be conjugated with fluorescent molecules, metallic nanoparticles, or quantum dots to aid in rapid detection of a variety of target molecules by target-induced structure switch (TISS) mode. Although intensive research is being carried out for further improvements of FNAs as sensors, challenges remain in integrating such bio-recognition element with advanced transduction platform to enable its use as a networked analytical system for tailor made analysis of environmental monitoring.
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Affiliation(s)
- Arghya Sett
- Bioengineering Research Laboratory, Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India
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13
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Furukawa K, Minakawa N. Allosteric control of a DNA-hydrolyzing deoxyribozyme with short oligonucleotides and its application in DNA logic gates. Org Biomol Chem 2014; 12:3344-8. [PMID: 24740418 DOI: 10.1039/c4ob00451e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Allosteric control of deoxyribozymes is useful for a broad range of practical applications, such as nucleic acid sensing and DNA-computing. We found that the catalytic activity of a DNA-hydrolyzing deoxyribozyme could be allosterically regulated by adding short oligonucleotides. We used this technique to construct deoxyribozyme-based logic gates.
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Affiliation(s)
- Kazuhiro Furukawa
- Graduate School of Pharmaceutical Sciences, The University of Tokushima, Shomachi 1-78-1, Tokushima 770-8505, Japan.
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14
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Pitchiaya S, Heinicke LA, Custer TC, Walter NG. Single molecule fluorescence approaches shed light on intracellular RNAs. Chem Rev 2014; 114:3224-65. [PMID: 24417544 PMCID: PMC3968247 DOI: 10.1021/cr400496q] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Sethuramasundaram Pitchiaya
- Single Molecule Analysis in Real-Time (SMART)
Center, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Single Molecule Analysis Group, Department of
Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Laurie A. Heinicke
- Single Molecule Analysis Group, Department of
Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Thomas C. Custer
- Program in Chemical Biology, University of Michigan,
Ann Arbor, MI 48109-1055, USA
| | - Nils G. Walter
- Single Molecule Analysis in Real-Time (SMART)
Center, University of Michigan, Ann Arbor, MI 48109-1055, USA
- Single Molecule Analysis Group, Department of
Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
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15
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Hickey SF, Hammond MC. Structure-guided design of fluorescent S-adenosylmethionine analogs for a high-throughput screen to target SAM-I riboswitch RNAs. CHEMISTRY & BIOLOGY 2014; 21:345-56. [PMID: 24560607 PMCID: PMC4074398 DOI: 10.1016/j.chembiol.2014.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/12/2013] [Accepted: 01/03/2014] [Indexed: 10/25/2022]
Abstract
Many classes of S-adenosylmethionine (SAM)-binding RNAs and proteins are of interest as potential drug targets in diverse therapeutic areas, from infectious diseases to cancer. In the former case, the SAM-I riboswitch is an attractive target because this structured RNA element is found only in bacterial mRNAs and regulates multiple genes in several human pathogens. Here, we describe the synthesis of stable and fluorescent analogs of SAM in which the fluorophore is introduced through a functionalizable linker to the ribose. A Cy5-labeled SAM analog was shown to bind several SAM-I riboswitches via in-line probing and fluorescence polarization assays, including one from Staphylococcus aureus that controls the expression of SAM synthetase in this organism. A fluorescent ligand displacement assay was developed and validated for high-throughput screening of compounds to target the SAM-I riboswitch class.
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Affiliation(s)
- Scott F Hickey
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; Synthetic Biology Institute, University of California, Berkeley, Berkely, CA 94720, USA
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Synthetic Biology Institute, University of California, Berkeley, Berkely, CA 94720, USA.
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16
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Suddala KC, Rinaldi AJ, Feng J, Mustoe AM, Eichhorn CD, Liberman JA, Wedekind JE, Al-Hashimi HM, Brooks CL, Walter NG. Single transcriptional and translational preQ1 riboswitches adopt similar pre-folded ensembles that follow distinct folding pathways into the same ligand-bound structure. Nucleic Acids Res 2013; 41:10462-75. [PMID: 24003028 PMCID: PMC3905878 DOI: 10.1093/nar/gkt798] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Riboswitches are structural elements in the 5′ untranslated regions of many bacterial messenger RNAs that regulate gene expression in response to changing metabolite concentrations by inhibition of either transcription or translation initiation. The preQ1 (7-aminomethyl-7-deazaguanine) riboswitch family comprises some of the smallest metabolite sensing RNAs found in nature. Once ligand-bound, the transcriptional Bacillus subtilis and translational Thermoanaerobacter tengcongensis preQ1 riboswitch aptamers are structurally similar RNA pseudoknots; yet, prior structural studies have characterized their ligand-free conformations as largely unfolded and folded, respectively. In contrast, through single molecule observation, we now show that, at near-physiological Mg2+ concentration and pH, both ligand-free aptamers adopt similar pre-folded state ensembles that differ in their ligand-mediated folding. Structure-based Gō-model simulations of the two aptamers suggest that the ligand binds late (Bacillus subtilis) and early (Thermoanaerobacter tengcongensis) relative to pseudoknot folding, leading to the proposal that the principal distinction between the two riboswitches lies in their relative tendencies to fold via mechanisms of conformational selection and induced fit, respectively. These mechanistic insights are put to the test by rationally designing a single nucleotide swap distal from the ligand binding pocket that we find to predictably control the aptamers′ pre-folded states and their ligand binding affinities.
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Affiliation(s)
- Krishna C Suddala
- Biophysics, University of Michigan, Ann Arbor, MI 48109, USA, Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA, Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109, USA, Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA and Center for Theoretical Biological Physics, University of California San Diego, San Diego, CA 92037, USA
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17
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Nesterova IV, Elsiddieg SO, Nesterov EE. Design and evaluation of an i-motif-based allosteric control mechanism in DNA-hairpin molecular devices. J Phys Chem B 2013; 117:10115-21. [PMID: 23941235 DOI: 10.1021/jp405230g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Molecular devices designed to assess and manipulate biologically relevant conditions with required accuracy and precision play an essential role in life sciences research. Incorporating allosteric regulation mechanism is an attractive strategy toward more efficient artificial sensing and switching systems. Herein, we report on a new principle of regulating switching parameters of a DNA-based molecular device based on allosteric interaction between spatially separated hairpin stem and a tetraplexed fragment (i.e., i-motif). We characterized thermodynamic and kinetic effects arising from interaction between functional domains of the device and demonstrated the potential of applying the allosteric control principle for rational design of sensors and switches with precisely defined operational characteristics.
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Affiliation(s)
- Irina V Nesterova
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
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18
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Ceres P, Garst AD, Marcano-Velázquez JG, Batey RT. Modularity of select riboswitch expression platforms enables facile engineering of novel genetic regulatory devices. ACS Synth Biol 2013; 2:463-72. [PMID: 23654267 DOI: 10.1021/sb4000096] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
RNA-based biosensors and regulatory devices have received significant attention for their potential in a broad array of synthetic biology applications. One of the primary difficulties in engineering these molecules is the lack of facile methods to link sensory modules, or aptamers, to readout domains. Such efforts typically require extensive screening or selection of sequences that facilitate interdomain communication. Bacteria have evolved a widespread form of gene regulation known as riboswitches that perform this task with sufficient fidelity to control expression of biosynthetic and transport proteins essential for normal cellular homeostasis. In this work, we demonstrate that select riboswitch readout domains, called expression platforms, are modular in that they can host a variety of natural and synthetic aptamers to create novel chimeric RNAs that regulate transcription both in vitro and in vivo. Importantly, this technique does not require selection of device-specific "communication modules" required to transmit ligand binding to the regulatory domain, enabling rapid engineering of novel functional RNAs.
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Affiliation(s)
- Pablo Ceres
- Department
of Chemistry and Biochemistry, University of Colorado at Boulder, Campus Box 596,
Boulder, Colorado 80309-0596, United States
| | - Andrew D. Garst
- Department
of Chemistry and Biochemistry, University of Colorado at Boulder, Campus Box 596,
Boulder, Colorado 80309-0596, United States
| | - Joan G. Marcano-Velázquez
- Department
of Chemistry and Biochemistry, University of Colorado at Boulder, Campus Box 596,
Boulder, Colorado 80309-0596, United States
| | - Robert T. Batey
- Department
of Chemistry and Biochemistry, University of Colorado at Boulder, Campus Box 596,
Boulder, Colorado 80309-0596, United States
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19
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Carter JR, Balaraman V, Kucharski CA, Fraser TS, Fraser MJ. A novel dengue virus detection method that couples DNAzyme and gold nanoparticle approaches. Virol J 2013; 10:201. [PMID: 23809208 PMCID: PMC3765938 DOI: 10.1186/1743-422x-10-201] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 04/08/2013] [Indexed: 11/15/2022] Open
Abstract
Background Recent epidemics of dengue viruses (DENV) coupled with new outbreaks on the horizon have renewed the demand for novel detection methods that have the ability to identify this viral pathogen prior to the manifestation of symptoms. The ability to detect DENV in a timely manner is essential for rapid recovery from disease symptoms. A modified lab-derived 10-23 DNAzyme tethered to gold nanoparticles provides a powerful tool for the detection of viruses, such as DENV. Results We examined the effectiveness of coupling DNAzyme (DDZ) activation to the salt-induced aggregation of gold nanoparticles (AuNP) to detect dengue virus (DENV) progeny in mosquito cells. A DNAzyme was designed to recognize the 5’ cyclization sequence (5’ CS) that is conserved among all DENV, and conjugated to AuNPs. DDZ-AuNP has demonstrated the ability to detect the genomic RNA of our model dengue strain, DENV-2 NGC, isolated from infected Aedes albopictus C6/36 cells. These targeting events lead to the rapid aggregation of AuNPs, resulting in a red to clear color transition of the reaction mixes, and thus positive detection of the DENV RNA genome. The inclusion of SDS in the reaction mixture permitted the detection of DENV directly from cell culture supernatants without additional sample processing. Specificity assays demonstrated detection is DENV-specific, while sensitivity assays confirm detection at levels of 1 × 101 TCID50 units. These results demonstrate DDZ-AuNP effectively detects DENV genomes in a sequence specific manner and at concentrations that are practical for field use. Conclusions We have developed an effective detection assay using DNAzyme catalysis coupled with AuNP aggregation for the detection of DENV genomes in a sequence specific manner. Full development of our novel DDZ-AuNP detection method will provide a practical, rapid, and low cost alternative for the detection of DENV in mosquito cells and tissues, and possibly infected patient serum, in a matter of minutes with little to no specialized training required.
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Affiliation(s)
- James R Carter
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, IN 46556, USA.
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20
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Protein mechanics: how force regulates molecular function. Biochim Biophys Acta Gen Subj 2013; 1830:4762-8. [PMID: 23791949 DOI: 10.1016/j.bbagen.2013.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 05/26/2013] [Accepted: 06/04/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND Regulation of proteins is ubiquitous and vital for any organism. Protein activity can be altered chemically, by covalent modifications or non-covalent binding of co-factors. Mechanical forces are emerging as an additional way of regulating proteins, by inducing a conformational change or by partial unfolding. SCOPE We review some advances in experimental and theoretical techniques to study protein allostery driven by mechanical forces, as opposed to the more conventional ligand driven allostery. In this respect, we discuss recent single molecule pulling experiments as they have substantially augmented our view on the protein allostery by mechanical signals in recent years. Finally, we present a computational analysis technique, Force Distribution Analysis, that we developed to reveal allosteric pathways in proteins. MAJOR CONCLUSIONS Any kind of external perturbation, being it ligand binding or mechanical stretching, can be viewed as an external force acting on the macromolecule, rendering force-based experimental or computational techniques, a very general approach to the mechanics involved in protein allostery. GENERAL SIGNIFICANCE This unifying view might aid to decipher how complex allosteric protein machineries are regulated on the single molecular level.
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21
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Selecting Molecular Recognition. What Can Existing Aptamers Tell Us about Their Inherent Recognition Capabilities and Modes of Interaction? Pharmaceuticals (Basel) 2012; 5:493-513. [PMID: 24281560 PMCID: PMC3763653 DOI: 10.3390/ph5050493] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/19/2012] [Accepted: 05/10/2012] [Indexed: 01/02/2023] Open
Abstract
The use of nucleic acid derived aptamers has rapidly expanded since the introduction of SELEX in 1990. Nucleic acid aptamers have demonstrated their ability to target a broad range of molecules in ways that rival antibodies, but advances have been very uneven for different biochemical classes of targets, and clinical applications have been slow to emerge. What sets different aptamers apart from each other and from rivaling molecular recognition platforms, specifically proteins? What advantages do aptamers as a reagent class offer, and how do the chemical properties and selection procedures of aptamers influence their function? Do the building blocks of nucleic acid aptamers dictate inherent limitations in the nature of molecular targets, and do existing aptamers give us insight in how these challenges might be overcome? This review is written as an introduction for potential endusers of aptamer technology who are evaluating the advantages of aptamers as a versatile, affordable, yet highly expandable platform to target a broad range of biological processes or interactions.
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22
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Carothers JM, Goler JA, Juminaga D, Keasling JD. Model-driven engineering of RNA devices to quantitatively program gene expression. Science 2012; 334:1716-9. [PMID: 22194579 DOI: 10.1126/science.1212209] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The models and simulation tools available to design functionally complex synthetic biological devices are very limited. We formulated a design-driven approach that used mechanistic modeling and kinetic RNA folding simulations to engineer RNA-regulated genetic devices that control gene expression. Ribozyme and metabolite-controlled, aptazyme-regulated expression devices with quantitatively predictable functions were assembled from components characterized in vitro, in vivo, and in silico. The models and design strategy were verified by constructing 28 Escherichia coli expression devices that gave excellent quantitative agreement between the predicted and measured gene expression levels (r = 0.94). These technologies were applied to engineer RNA-regulated controls in metabolic pathways. More broadly, we provide a framework for studying RNA functions and illustrate the potential for the use of biochemical and biophysical modeling to develop biological design methods.
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Affiliation(s)
- James M Carothers
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley CA 94720, USA
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23
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He Y, Lu Y. Metal-ion-dependent folding of a uranyl-specific DNAzyme: insight into function from fluorescence resonance energy transfer studies. Chemistry 2011; 17:13732-42. [PMID: 22052817 DOI: 10.1002/chem.201100352] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 07/25/2011] [Indexed: 01/28/2023]
Abstract
Fluorescence resonance energy transfer (FRET) has been used to study the global folding of an uranyl (UO(2)(2+))-specific 39E DNAzyme in the presence of Mg(2+), Zn(2+), Pb(2+), or UO(2)(2+). At pH 5.5 and physiological ionic strength (100 mM Na(+)), two of the three stems in this DNAzyme folded into a compact structure in the presence of Mg(2+) or Zn(2+). However, no folding occurred in the presence of Pb(2+) or UO(2)(2+); this is analogous to the "lock-and-key" catalysis mode first observed in the Pb(2+)-specific 8-17 DNAzyme. However, Mg(2+) and Zn(2+) exert different effects on the 8-17 and 39E DNAzymes. Whereas Mg(2+) or Zn(2+)-dependent folding promoted 8-17 DNAzyme activity, the 39E DNAzyme folding induced by Mg(2+) or Zn(2+) inhibited UO(2)(2+)-specific activity. Group IIA series of metal ions (Mg(2+), Ca(2+), Sr(2+)) also caused global folding of the 39E DNAzyme, for which the apparent binding affinity between these metal ions and the DNAzyme decreases as the ionic radius of the metal ions increases. Because the ionic radius of Sr(2+) (1.12 Å) is comparable to that of Pb(2+) (1.20 Å), but contrary to Pb(2+), Sr(2+) induces the DNAzyme to fold under identical conditions, ionic size alone cannot account for the unique folding behaviors induced by Pb(2+) and UO(2)(2+). Under low ionic strength (30 mM Na(+)), all four metal ions (Mg(2+), Zn(2+), Pb(2+), and UO(2)(2+)), caused 39E DNAzyme folding, suggesting that metal ions can neutralize the negative charge of DNA-backbone phosphates in addition to playing specific catalytic roles. Mg(2+) at low (<2 mM) concentration promoted UO(2)(2+)-specific activity, whereas Mg(2+) at high (>2 mM) concentration inhibited the UO(2)(2+)-specific activity. Therefore, the lock-and-key mode of DNAzymes depends on ionic strength, and the 39E DNAzyme is in the lock-and-key mode only at ionic strengths of 100 mM or greater.
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Affiliation(s)
- Ying He
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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McDowell SE, Jun JM, Walter NG. Long-range tertiary interactions in single hammerhead ribozymes bias motional sampling toward catalytically active conformations. RNA (NEW YORK, N.Y.) 2010; 16:2414-2426. [PMID: 20921269 PMCID: PMC2995402 DOI: 10.1261/rna.1829110] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 08/30/2010] [Indexed: 05/29/2023]
Abstract
Enzymes generally are thought to derive their functional activity from conformational motions. The limited chemical variation in RNA suggests that such structural dynamics may play a particularly important role in RNA function. Minimal hammerhead ribozymes are known to cleave efficiently only in ∼ 10-fold higher than physiologic concentrations of Mg(2+) ions. Extended versions containing native loop-loop interactions, however, show greatly enhanced catalytic activity at physiologically relevant Mg(2+) concentrations, for reasons that are still ill-understood. Here, we use Mg(2+) titrations, activity assays, ensemble, and single molecule fluorescence resonance energy transfer (FRET) approaches, combined with molecular dynamics (MD) simulations, to ask what influence the spatially distant tertiary loop-loop interactions of an extended hammerhead ribozyme have on its structural dynamics. By comparing hammerhead variants with wild-type, partially disrupted, and fully disrupted loop-loop interaction sequences we find that the tertiary interactions lead to a dynamic motional sampling that increasingly populates catalytically active conformations. At the global level the wild-type tertiary interactions lead to more frequent, if transient, encounters of the loop-carrying stems, whereas at the local level they lead to an enrichment in favorable in-line attack angles at the cleavage site. These results invoke a linkage between RNA structural dynamics and function and suggest that loop-loop interactions in extended hammerhead ribozymes-and Mg(2+) ions that bind to minimal ribozymes-may generally allow more frequent access to a catalytically relevant conformation(s), rather than simply locking the ribozyme into a single active state.
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Abelson J, Blanco M, Ditzler MA, Fuller F, Aravamudhan P, Wood M, Villa T, Ryan DE, Pleiss JA, Maeder C, Guthrie C, Walter NG. Conformational dynamics of single pre-mRNA molecules during in vitro splicing. Nat Struct Mol Biol 2010; 17:504-12. [PMID: 20305654 DOI: 10.1038/nsmb.1767] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Accepted: 12/16/2009] [Indexed: 11/09/2022]
Abstract
The spliceosome is a complex small nuclear RNA (snRNA)-protein machine that removes introns from pre-mRNAs via two successive phosphoryl transfer reactions. The chemical steps are isoenergetic, yet splicing requires at least eight RNA-dependent ATPases responsible for substantial conformational rearrangements. To comprehensively monitor pre-mRNA conformational dynamics, we developed a strategy for single-molecule FRET (smFRET) that uses a small, efficiently spliced yeast pre-mRNA, Ubc4, in which donor and acceptor fluorophores are placed in the exons adjacent to the 5' and 3' splice sites. During splicing in vitro, we observed a multitude of generally reversible time- and ATP-dependent conformational transitions of individual pre-mRNAs. The conformational dynamics of branchpoint and 3'-splice site mutants differ from one another and from wild type. Because all transitions are reversible, spliceosome assembly appears to be occurring close to thermal equilibrium.
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Affiliation(s)
- John Abelson
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA.
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Ogawa A. Biofunction-assisted sensors based on a new method for converting aptazyme activity into reporter protein expression with high efficiency in wheat germ extract. Chembiochem 2010; 10:2465-8. [PMID: 19750532 DOI: 10.1002/cbic.200900497] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Atsushi Ogawa
- Senior Research Fellow Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
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Design principles for ligand-sensing, conformation-switching ribozymes. PLoS Comput Biol 2009; 5:e1000620. [PMID: 20041206 PMCID: PMC2789328 DOI: 10.1371/journal.pcbi.1000620] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 11/17/2009] [Indexed: 11/19/2022] Open
Abstract
Nucleic acid sensor elements are proving increasingly useful in biotechnology and biomedical applications. A number of ligand-sensing, conformational-switching ribozymes (also known as allosteric ribozymes or aptazymes) have been generated by some combination of directed evolution or rational design. Such sensor elements typically fuse a molecular recognition domain (aptamer) with a catalytic signal generator (ribozyme). Although the rational design of aptazymes has begun to be explored, the relationships between the thermodynamics of aptazyme conformational changes and aptazyme performance in vitro and in vivo have not been examined in a quantitative framework. We have therefore developed a quantitative and predictive model for aptazymes as biosensors in vitro and as riboswitches in vivo. In the process, we have identified key relationships (or dimensionless parameters) that dictate aptazyme performance, and in consequence, established equations for precisely engineering aptazyme function. In particular, our analysis quantifies the intrinsic trade-off between ligand sensitivity and the dynamic range of activity. We were also able to determine how in vivo parameters, such as mRNA degradation rates, impact the design and function of aptazymes when used as riboswitches. Using this theoretical framework we were able to achieve quantitative agreement between our models and published data. In consequence, we are able to suggest experimental guidelines for quantitatively predicting the performance of aptazyme-based riboswitches. By identifying factors that limit the performance of previously published systems we were able to generate immediately testable hypotheses for their improvement. The robust theoretical framework and identified optimization parameters should now enable the precision design of aptazymes for biotechnological and clinical applications. Aptamers are nucleic acids that bind their cognate ligands (ranging from metal ions to small molecules to proteins) specifically and tightly. Through rational design and/or directed evolution, aptamers can be engineered into allosteric nucleic acids whose conformations can be regulated by their ligands. Aptamer beacons, aptazymes, and riboswitches all undergo ligand-dependent conformational changes, and have been adapted to signal the concentration of their ligands. However, there is currently no model that can be used to predict how the energetics of conformational change affects signaling, either in vitro or in vivo. We have developed a model that identifies what parameters can be optimized to best yield signals. By focusing on these parameters, it should be possible to more readily design or select more effective conformation-switching nucleic acid biosensors.
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Helm M, Kobitski AY, Nienhaus GU. Single-molecule Förster resonance energy transfer studies of RNA structure, dynamics and function. Biophys Rev 2009; 1:161. [PMID: 28510027 PMCID: PMC5418384 DOI: 10.1007/s12551-009-0018-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 10/09/2009] [Indexed: 11/24/2022] Open
Abstract
Single-molecule fluorescence microscopy experiments on RNA molecules brought to light the highly complex dynamics of key biological processes, including RNA folding, catalysis of ribozymes, ligand sensing of riboswitches and aptamers, and protein synthesis in the ribosome. By using highly advanced biophysical spectroscopy techniques in combination with sophisticated biochemical synthesis approaches, molecular dynamics of individual RNA molecules can be observed in real time and under physiological conditions in unprecedented detail that cannot be achieved with bulk experiments. Here, we review recent advances in RNA folding and functional studies of RNA and RNA-protein complexes addressed by using single-molecule Förster (fluorescence) resonance energy transfer (smFRET) technique.
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Affiliation(s)
- Mark Helm
- Institute of Pharmacy, University of Mainz, Staudinger Weg 5, 55128, Mainz, Germany.
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120, Heidelberg, Germany.
| | - Andrei Yu Kobitski
- Institute of Applied Physics and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76128, Karlsruhe, Germany
| | - G Ulrich Nienhaus
- Institute of Applied Physics and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76128, Karlsruhe, Germany
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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