1
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Ogawa A, Fujikawa M, Onishi K, Takahashi H. Cell-Free Biosensors Based on Modular Eukaryotic Riboswitches That Function in One Pot at Ambient Temperature. ACS Synth Biol 2024. [PMID: 38913391 DOI: 10.1021/acssynbio.4c00341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
Artificial riboswitches responsive to user-defined analytes can be constructed by successfully inserting in vitro selected aptamers, which bind to the analytes, into untranslated regions of mRNA. Among them, eukaryotic riboswitches are more promising as biosensors than bacterial ones because they function well at ambient temperature. In addition, cell-free expression systems allow the broader use of these riboswitches as cell-free biosensors in an environmentally friendly manner without cellular limitations. The current best cell-free eukaryotic riboswitch regulates eukaryotic canonical translation initiation through self-cleavage mediated by an implanted analyte-responsive ribozyme (i.e., an aptazyme, an aptamer-ribozyme fusion). However, it has critical flaws as a sensor: due to the less-active ribozyme used, self-cleavage and translation reactions must be conducted separately and sequentially, and a different aptazyme has to be selected to change the analyte specificity, even if an aptamer for the next analyte is available. We here stepwise engineered novel types of cell-free eukaryotic riboswitches that harness highly active self-cleavage and thus require no reaction partitioning. Despite the single-step and one-pot reaction, these riboswitches showed higher analyte dose dependency and sensitivities than the current best cell-free eukaryotic riboswitch requiring multistep reactions. In addition, the analyte specificity can be changed in an extremely facile way, simply by aptamer substitution (and the subsequent simple fine-tuning for giant aptamers). Given that cell-free systems can be lyophilized for storage and transport, the present one-pot and thus easy-to-handle cell-free biosensors utilizing eukaryotic riboswitches are expected to be widely used for on-the-spot sensing of analytes at ambient temperature.
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Affiliation(s)
- Atsushi Ogawa
- Proteo-Science Center, Ehime University, 2-5 Bunkyo, Matsuyama ,Ehime 790-8577, Japan
| | - Masahiro Fujikawa
- Proteo-Science Center, Ehime University, 2-5 Bunkyo, Matsuyama ,Ehime 790-8577, Japan
| | - Kazuki Onishi
- Proteo-Science Center, Ehime University, 2-5 Bunkyo, Matsuyama ,Ehime 790-8577, Japan
| | - Hajime Takahashi
- Proteo-Science Center, Ehime University, 2-5 Bunkyo, Matsuyama ,Ehime 790-8577, Japan
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2
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Sumi S, Hamada M, Saito H. Deep generative design of RNA family sequences. Nat Methods 2024; 21:435-443. [PMID: 38238559 DOI: 10.1038/s41592-023-02148-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 12/07/2023] [Indexed: 03/13/2024]
Abstract
RNA engineering has immense potential to drive innovation in biotechnology and medicine. Despite its importance, a versatile platform for the automated design of functional RNA is still lacking. Here, we propose RNA family sequence generator (RfamGen), a deep generative model that designs RNA family sequences in a data-efficient manner by explicitly incorporating alignment and consensus secondary structure information. RfamGen can generate novel and functional RNA family sequences by sampling points from a semantically rich and continuous representation. We have experimentally demonstrated the versatility of RfamGen using diverse RNA families. Furthermore, we confirmed the high success rate of RfamGen in designing functional ribozymes through a quantitative massively parallel assay. Notably, RfamGen successfully generates artificial sequences with higher activity than natural sequences. Overall, RfamGen significantly improves our ability to design functional RNA and opens up new potential for generative RNA engineering in synthetic biology.
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Affiliation(s)
- Shunsuke Sumi
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Michiaki Hamada
- Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
- Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan.
- Graduate School of Medicine, Nippon Medical School, Tokyo, Japan.
| | - Hirohide Saito
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan.
- Graduate School of Medicine, Kyoto University, Kyoto, Japan.
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3
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Hurter F, Halbritter ALJ, Ahmad IM, Braun M, Sigurdsson ST, Wachtveitl J. Förster resonance energy transfer within the neomycin aptamer. Phys Chem Chem Phys 2024; 26:7157-7165. [PMID: 38348887 DOI: 10.1039/d3cp05728c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Förster resonance energy transfer (FRET) measurements between two dyes is a powerful method to interrogate both structure and dynamics of biopolymers. The intensity of a fluorescence signal in a FRET measurement is dependent on both the distance and the relative orientation of the dyes. The latter can at the same time both complicate the analysis and give more detailed information. Here we present a detailed spectroscopic study of the energy transfer between the rigid FRET labels Çmf (donor) and tCnitro (quencher/acceptor) within the neomycin aptamer N1. The energy transfer originates from multiple emitting states of the donor and occurs on a low picosecond to nanosecond time-scale. To fully characterize the energy transfer, ultrafast transient absorption measurements were performed in conjunction with static fluorescence and time-correlated single photon counting (TCSPC) measurements, showing a clear distance dependence of both signal intensity and lifetime. Using a known NMR structure of the ligand-bound neomycin aptamer, the distance between the two labels was used to estimate κ2 and, therefore, make qualitative statements about the change in orientation after ligand binding with unprecedented temporal and spatial resolution. The advantages and potential applications of absorption-based methods using rigid labels for the characterization of FRET processes are discussed.
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Affiliation(s)
- Florian Hurter
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Main, Max-von-Laue-Str. 7, Frankfurt 60438, Germany.
| | - Anna-Lena J Halbritter
- Science Institute, University of Iceland, Dunhaga 3, Reykjavik 107, Iceland
- Department of Chemistry, Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Iram M Ahmad
- Science Institute, University of Iceland, Dunhaga 3, Reykjavik 107, Iceland
| | - Markus Braun
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Main, Max-von-Laue-Str. 7, Frankfurt 60438, Germany.
| | | | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Main, Max-von-Laue-Str. 7, Frankfurt 60438, Germany.
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4
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Matteau D, Duval A, Baby V, Rodrigue S. Mesoplasma florum: a near-minimal model organism for systems and synthetic biology. Front Genet 2024; 15:1346707. [PMID: 38404664 PMCID: PMC10884336 DOI: 10.3389/fgene.2024.1346707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/24/2024] [Indexed: 02/27/2024] Open
Abstract
Mesoplasma florum is an emerging model organism for systems and synthetic biology due to its small genome (∼800 kb) and fast growth rate. While M. florum was isolated and first described almost 40 years ago, many important aspects of its biology have long remained uncharacterized due to technological limitations, the absence of dedicated molecular tools, and since this bacterial species has not been associated with any disease. However, the publication of the first M. florum genome in 2004 paved the way for a new era of research fueled by the rise of systems and synthetic biology. Some of the most important studies included the characterization and heterologous use of M. florum regulatory elements, the development of the first replicable plasmids, comparative genomics and transposon mutagenesis, whole-genome cloning in yeast, genome transplantation, in-depth characterization of the M. florum cell, as well as the development of a high-quality genome-scale metabolic model. The acquired data, knowledge, and tools will greatly facilitate future genome engineering efforts in M. florum, which could next be exploited to rationally design and create synthetic cells to advance fundamental knowledge or for specific applications.
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Affiliation(s)
- Dominick Matteau
- Département de biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Anthony Duval
- Département de biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Vincent Baby
- Centre de diagnostic vétérinaire de l'Université de Montréal, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | - Sébastien Rodrigue
- Département de biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
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5
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Luo L, Jea JDY, Wang Y, Chao PW, Yen L. Control of mammalian gene expression by modulation of polyA signal cleavage at 5' UTR. Nat Biotechnol 2024:10.1038/s41587-023-01989-0. [PMID: 38168982 DOI: 10.1038/s41587-023-01989-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 09/13/2023] [Indexed: 01/05/2024]
Abstract
The ability to control gene expression in mammalian cells is crucial for safe and efficacious gene therapies and for elucidating gene functions. Current gene regulation systems have limitations such as harmful immune responses or low efficiency. We describe the pA regulator, an RNA-based switch that controls mammalian gene expression through modulation of a synthetic polyA signal (PAS) cleavage introduced into the 5' UTR of a transgene. The cleavage is modulated by a 'dual-mechanism'-(1) aptamer clamping to inhibit PAS cleavage and (2) drug-induced alternative splicing that removes the PAS, both activated by drug binding. This RNA-based methodology circumvents the immune responses observed in other systems and achieves a 900-fold induction with an EC50 of 0.5 µg ml-1 tetracycline (Tc), which is well within the FDA-approved dose range. The pA regulator effectively controls the luciferase transgene in live mice and the endogenous CD133 gene in human cells, in a dose-dependent and reversible manner with long-term stability.
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Affiliation(s)
- Liming Luo
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Jocelyn Duen-Ya Jea
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Yan Wang
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Pei-Wen Chao
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Laising Yen
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA.
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.
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6
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Takahashi H, Fujikawa M, Ogawa A. Rational design of eukaryotic riboswitches that up-regulate IRES-mediated translation initiation with high switching efficiency through a kinetic trapping mechanism in vitro. RNA (NEW YORK, N.Y.) 2023; 29:1950-1959. [PMID: 37704221 PMCID: PMC10653380 DOI: 10.1261/rna.079778.123] [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: 07/20/2023] [Accepted: 09/05/2023] [Indexed: 09/15/2023]
Abstract
In general, riboswitches functioning through a cotranscriptional kinetic trapping mechanism (kt-riboswitches) show higher switching efficiencies in response to practical concentrations of their ligand molecules than eq-riboswitches, which function by an equilibrium mechanism. However, the former have been much more difficult to design due to their more complex mechanism. We here successfully developed a rational strategy for constructing eukaryotic kt-riboswitches that ligand-dependently enhance translation initiation mediated by an internal ribosome entry site (IRES). This was achieved both by utilizing some predicted structural features of a highly efficient bacterial kt-riboswitch identified through screening and by completely decoupling an aptamer domain from the IRES. Three kt-riboswitches optimized through this strategy, each responding to a different ligand, exhibited three- to sevenfold higher induction ratios (up to ∼90) than previously optimized eq-riboswitches regulating the same IRES-mediated translation in wheat germ extract. Because the IRES used functions well in various eukaryotic expression systems, these types of kt-riboswitches are expected to serve as major eukaryotic gene regulators based on RNA. In addition, the present strategy could be applied to the rational construction of other types of kt-riboswitches, including those functioning in bacterial expression systems.
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Affiliation(s)
- Hajime Takahashi
- Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Masahiro Fujikawa
- Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Atsushi Ogawa
- Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
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7
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Ortega AD. Real-Time Assessment of Intracellular Metabolites in Single Cells through RNA-Based Sensors. Biomolecules 2023; 13:biom13050765. [PMID: 37238635 DOI: 10.3390/biom13050765] [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: 03/24/2023] [Revised: 04/24/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
Quantification of the concentration of particular cellular metabolites reports on the actual utilization of metabolic pathways in physiological and pathological conditions. Metabolite concentration also constitutes the readout for screening cell factories in metabolic engineering. However, there are no direct approaches that allow for real-time assessment of the levels of intracellular metabolites in single cells. In recent years, the modular architecture of natural bacterial RNA riboswitches has inspired the design of genetically encoded synthetic RNA devices that convert the intracellular concentration of a metabolite into a quantitative fluorescent signal. These so-called RNA-based sensors are composed of a metabolite-binding RNA aptamer as the sensor domain, connected through an actuator segment to a signal-generating reporter domain. However, at present, the variety of available RNA-based sensors for intracellular metabolites is still very limited. Here, we go through natural mechanisms for metabolite sensing and regulation in cells across all kingdoms, focusing on those mediated by riboswitches. We review the design principles underlying currently developed RNA-based sensors and discuss the challenges that hindered the development of novel sensors and recent strategies to address them. We finish by introducing the current and potential applicability of synthetic RNA-based sensors for intracellular metabolites.
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Affiliation(s)
- Alvaro Darío Ortega
- Department of Cell Biology, Faculty of Biological Sciences, Complutense University of Madrid, 28040 Madrid, Spain
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8
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Dang Z, Gao M, Wang L, Wu J, Guo Y, Zhu Z, Huang H, Kang G. Synthetic bacterial therapies for intestinal diseases based on quorum- sensing circuits. Biotechnol Adv 2023; 65:108142. [PMID: 36977440 DOI: 10.1016/j.biotechadv.2023.108142] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 03/22/2023] [Accepted: 03/24/2023] [Indexed: 03/28/2023]
Abstract
Bacterial therapy has become a key strategy against intestinal infectious diseases in recent years. Moreover, regulating the gut microbiota through traditional fecal microbiota transplantation and supplementation of probiotics faces controllability, efficacy, and safety challenges. The infiltration and emergence of synthetic biology and microbiome provide an operational and safe treatment platform for live bacterial biotherapies. Synthetic bacterial therapy can artificially manipulate bacteria to produce and deliver therapeutic drug molecules. This method has the advantages of solid controllability, low toxicity, strong therapeutic effects, and easy operation. As an essential tool for dynamic regulation in synthetic biology, quorum sensing (QS) has been widely used for designing complex genetic circuits to control the behavior of bacterial populations and achieve predefined goals. Therefore, QS-based synthetic bacterial therapy might become a new direction for the treatment of diseases. The pre-programmed QS genetic circuit can achieve a controllable production of therapeutic drugs on particular ecological niches by sensing specific signals released from the digestive system in pathological conditions, thereby realizing the integration of diagnosis and treatment. Based on this as well as the modular idea of synthetic biology, QS-based synthetic bacterial therapies are divided into an environmental signal sensing module (senses gut disease physiological signals), a therapeutic molecule producing module (plays a therapeutic role against diseases), and a population behavior regulating module (QS system). This review article summarized the structure and function of these three modules and discussed the rational design of QS gene circuits as a novel intervention strategy for intestinal diseases. Moreover, the application prospects of QS-based synthetic bacterial therapy were summarized. Finally, the challenges faced by these methods were analyzed to make the targeted recommendations for developing a successful therapeutic strategy for intestinal diseases.
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9
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Ogawa A, Inoue H, Itoh Y, Takahashi H. Facile Expansion of the Variety of Orthogonal Ligand/Aptamer Pairs for Artificial Riboswitches. ACS Synth Biol 2023; 12:35-42. [PMID: 36566430 DOI: 10.1021/acssynbio.2c00475] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
An RNA aptamer that induces suitable conformational changes upon binding to a user-defined ligand allows us to artificially construct a riboswitch, a ligand-dependent and cis-acting gene regulatory RNA. Although such an aptamer can be obtained through in vitro selection, it is still challenging to rationally expand the variety of orthogonal ligand/aptamer (ligand/riboswitch) pairs. To achieve this in a facile, selection-free way, we herein focused on a specific type of ligand, 6-nt nanosized DNA (nDNA) and its aptamer that was previously selected to construct a eukaryotic artificial riboswitch. Specifically, we merely mutated one or more possible Watson-Crick base pairs in the nDNA/aptamer (nDNA/riboswitch) interactions into another base pair or pairs. Using two sets that each had 16 comprehensive mutations, we obtained three groups of several orthogonal nDNA/riboswitch pairs. These pairs could be used to create complex gene circuits, including multiple simultaneous and/or multistep cascading regulations in synthetic biology.
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Affiliation(s)
- Atsushi Ogawa
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan
| | - Honami Inoue
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan
| | - Yu Itoh
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan
| | - Hajime Takahashi
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan
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10
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Kelvin D, Suess B. Tapping the potential of synthetic riboswitches: reviewing the versatility of the tetracycline aptamer. RNA Biol 2023; 20:457-468. [PMID: 37459466 DOI: 10.1080/15476286.2023.2234732] [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] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 07/20/2023] Open
Abstract
Synthetic riboswitches are a versatile class of regulatory elements that are becoming increasingly established in synthetic biology applications. They are characterized by their compact size and independence from auxiliary protein factors. While naturally occurring riboswitches were mostly discovered in bacteria, synthetic riboswitches have been designed for all domains of life. Published design strategies far exceed the number of riboswitches found in nature. A core element of any riboswitch is a binding domain, called an aptamer, which is characterized by high specificity and affinity for its ligand. Aptamers can be selected de novo, allowing the design of synthetic riboswitches against a broad spectrum of targets. The tetracycline aptamer has proven to be well suited for riboswitch engineering. Since its selection, it has been used in a variety of applications and is considered to be well established and characterized. Using the tetracycline aptamer as an example, we aim to discuss a large variety of design approaches for synthetic riboswitch engineering and their application. We aim to demonstrate the versatility of riboswitches in general and the high potential of synthetic RNA devices for creating new solutions in both the scientific and medical fields.
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Affiliation(s)
- Daniel Kelvin
- Fachbereich Biologie, TU Darmstadt, Darmstadt, Germany
| | - Beatrix Suess
- Fachbereich Biologie, TU Darmstadt, Darmstadt, Germany
- Centre for Synthetic Biology, TU Darmstadt, Darmstadt, Germany
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11
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Patterson AT, Styczynski MP. Rapid and Finely-Tuned Expression for Deployable Sensing Applications. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 186:141-161. [PMID: 37316621 DOI: 10.1007/10_2023_223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Organisms from across the tree of life have evolved highly efficient mechanisms for sensing molecules of interest using biomolecular machinery that can in turn be quite valuable for the development of biosensors. However, purification of such machinery for use in in vitro biosensors is costly, while the use of whole cells as in vivo biosensors often leads to long sensor response times and unacceptable sensitivity to the chemical makeup of the sample. Cell-free expression systems overcome these weaknesses by removing the requirements associated with maintaining living sensor cells, allowing for increased function in toxic environments and rapid sensor readout at a production cost that is often more reasonable than purification. Here, we focus on the challenge of implementing cell-free protein expression systems that meet the stringent criteria required for them to serve as the basis for field-deployable biosensors. Fine-tuning expression to meet these requirements can be achieved through careful selection of the sensing and output elements, as well as through optimization of reaction conditions via tuning of DNA/RNA concentrations, lysate preparation methods, and buffer conditions. Through careful sensor engineering, cell-free systems can continue to be successfully used for the production of tightly regulated, rapidly expressing genetic circuits for biosensors.
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Affiliation(s)
- Alexandra T Patterson
- 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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12
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Köbel T, Melo Palhares R, Fromm C, Szymanski W, Angelidou G, Glatter T, Georg J, Berghoff BA, Schindler D. An Easy-to-Use Plasmid Toolset for Efficient Generation and Benchmarking of Synthetic Small RNAs in Bacteria. ACS Synth Biol 2022; 11:2989-3003. [PMID: 36044590 PMCID: PMC9486967 DOI: 10.1021/acssynbio.2c00164] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Synthetic biology approaches life from the perspective of an engineer. Standardized and de novo design of genetic parts to subsequently build reproducible and controllable modules, for example, for circuit design, is a key element. To achieve this, natural systems and elements often serve as a blueprint for researchers. Regulation of protein abundance is controlled at DNA, mRNA, and protein levels. Many tools for the activation or repression of transcription or the destabilization of proteins are available, but easy-to-handle minimal regulatory elements on the mRNA level are preferable when translation needs to be modulated. Regulatory RNAs contribute considerably to regulatory networks in all domains of life. In particular, bacteria use small regulatory RNAs (sRNAs) to regulate mRNA translation. Slowly, sRNAs are attracting the interest of using them for broad applications in synthetic biology. Here, we promote a "plug and play" plasmid toolset to quickly and efficiently create synthetic sRNAs to study sRNA biology or their application in bacteria. We propose a simple benchmarking assay by targeting the acrA gene of Escherichia coli and rendering cells sensitive toward the β-lactam antibiotic oxacillin. We further highlight that it may be necessary to test multiple seed regions and sRNA scaffolds to achieve the desired regulatory effect. The described plasmid toolset allows quick construction and testing of various synthetic sRNAs based on the user's needs.
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Affiliation(s)
- Tania
S. Köbel
- RG
Schindler, Max-Planck-Institute for Terrestrial
Microbiology, Karl-von-Frisch-Street
10, 35043 Marburg, Germany,MaxGENESYS
Biofoundry, Max-Planck-Institute for Terrestrial
Microbiology, Karl-von-Frisch-Street
10, 35043 Marburg, Germany
| | - Rafael Melo Palhares
- RG
Schindler, Max-Planck-Institute for Terrestrial
Microbiology, Karl-von-Frisch-Street
10, 35043 Marburg, Germany,Institute
for Microbiology and Molecular Biology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany
| | - Christin Fromm
- Institute
for Microbiology and Molecular Biology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany
| | - Witold Szymanski
- Mass
Spectrometry and Proteomics Core Facility, Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Street 10, 35043 Marburg, Germany
| | - Georgia Angelidou
- Mass
Spectrometry and Proteomics Core Facility, Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Street 10, 35043 Marburg, Germany
| | - Timo Glatter
- Mass
Spectrometry and Proteomics Core Facility, Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Street 10, 35043 Marburg, Germany
| | - Jens Georg
- Institut
für Biologie III, Albert-Ludwigs-Universität
Freiburg, Schänzlestraße
1, 79104 Freiburg, Germany
| | - Bork A. Berghoff
- Institute
for Microbiology and Molecular Biology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany,
| | - Daniel Schindler
- RG
Schindler, Max-Planck-Institute for Terrestrial
Microbiology, Karl-von-Frisch-Street
10, 35043 Marburg, Germany,MaxGENESYS
Biofoundry, Max-Planck-Institute for Terrestrial
Microbiology, Karl-von-Frisch-Street
10, 35043 Marburg, Germany,
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13
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Cengic I, Cañadas IC, Minton NP, Hudson EP. Inducible CRISPR/Cas9 Allows for Multiplexed and Rapidly Segregated Single-Target Genome Editing in Synechocystis Sp. PCC 6803. ACS Synth Biol 2022; 11:3100-3113. [PMID: 35969224 PMCID: PMC9486961 DOI: 10.1021/acssynbio.2c00375] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Establishing various synthetic biology tools is crucial for the development of cyanobacteria for biotechnology use, especially tools that allow for precise and markerless genome editing in a time-efficient manner. Here, we describe a riboswitch-inducible CRISPR/Cas9 system, contained on a single replicative vector, for the model cyanobacterium Synechocystis sp. PCC 6803. A theophylline-responsive riboswitch allowed tight control of Cas9 expression, which enabled reliable transformation of the CRISPR/Cas9 vector intoSynechocystis. Induction of the CRISPR/Cas9 mediated various types of genomic edits, specifically deletions and insertions of varying size. The editing efficiency varied depending on the target and intended edit; smaller edits performed better, reaching, e.g., 100% for insertion of a FLAG-tag onto rbcL. Importantly, the single-vector CRISPR/Cas9 system mediated multiplexed editing of up to three targets in parallel inSynechocystis. All single-target and several double-target mutants were also fully segregated after the first round of induction. Lastly, a vector curing system based on the nickel-inducible expression of the toxic mazF (from Escherichia coli) was added to the CRISPR/Cas9 vector. This inducible system allowed for curing of the vector in 25-75% of screened colonies, enabling edited mutants to become markerless.
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Affiliation(s)
- Ivana Cengic
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, Stockholm 17121, Sweden
| | - Inés C. Cañadas
- BBSRC/EPSRC
Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Nigel P. Minton
- BBSRC/EPSRC
Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Elton P. Hudson
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, Stockholm 17121, Sweden,
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14
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Giarimoglou N, Kouvela A, Maniatis A, Papakyriakou A, Zhang J, Stamatopoulou V, Stathopoulos C. A Riboswitch-Driven Era of New Antibacterials. Antibiotics (Basel) 2022; 11:antibiotics11091243. [PMID: 36140022 PMCID: PMC9495366 DOI: 10.3390/antibiotics11091243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/01/2022] [Accepted: 09/08/2022] [Indexed: 11/26/2022] Open
Abstract
Riboswitches are structured non-coding RNAs found in the 5′ UTR of important genes for bacterial metabolism, virulence and survival. Upon the binding of specific ligands that can vary from simple ions to complex molecules such as nucleotides and tRNAs, riboswitches change their local and global mRNA conformations to affect downstream transcription or translation. Due to their dynamic nature and central regulatory role in bacterial metabolism, riboswitches have been exploited as novel RNA-based targets for the development of new generation antibacterials that can overcome drug-resistance problems. During recent years, several important riboswitch structures from many bacterial representatives, including several prominent human pathogens, have shown that riboswitches are ideal RNA targets for new compounds that can interfere with their structure and function, exhibiting much reduced resistance over time. Most interestingly, mainstream antibiotics that target the ribosome have been shown to effectively modulate the regulatory behavior and capacity of several riboswitches, both in vivo and in vitro, emphasizing the need for more in-depth studies and biological evaluation of new antibiotics. Herein, we summarize the currently known compounds that target several main riboswitches and discuss the role of mainstream antibiotics as modulators of T-box riboswitches, in the dawn of an era of novel inhibitors that target important bacterial regulatory RNAs.
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Alexandros Maniatis
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Athanasios Papakyriakou
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi, 15341 Athens, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | | | - Constantinos Stathopoulos
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
- Correspondence: ; Tel.: +30-2610-997932
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15
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Takahashi H, Okubo R, Ogawa A. Eukaryotic artificial ON-riboswitches that respond efficiently to mid-sized short peptides. Bioorg Med Chem Lett 2022; 71:128839. [PMID: 35654302 DOI: 10.1016/j.bmcl.2022.128839] [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: 04/12/2022] [Revised: 05/24/2022] [Accepted: 05/27/2022] [Indexed: 11/02/2022]
Abstract
We chose two types of mid-sized Arg-rich peptides (Rev-pep and Tat-pep) as ligands and used their aptamers to construct efficient eukaryotic ON-riboswitches (ligand-dependently upregulating riboswitches). Due to the aptamers' high affinities, the best Rev-pep-responsive and Tat-pep-responsive riboswitches obtained showed much higher switching efficiencies at low ligand concentrations than small ligand-responsive ON-riboswitches in the same mechanism. In addition, despite the high sequence similarity of Rev-pep and Tat-pep, the two best riboswitches were almost insensitive to each other's peptide ligand. Considering the high responsiveness and specificity along with the versatility of the expression platform used and the applicability of Arg-rich peptides, this orthogonal pair of riboswitches would be widely useful eukaryotic gene regulators or biosensors.
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Affiliation(s)
- Hajime Takahashi
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan
| | - Ryo Okubo
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan
| | - Atsushi Ogawa
- Proteo-Science Center, Ehime University, 3 Bunkyo, Matsuyama, Ehime 790-8577, Japan.
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16
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Harbaugh SV, Silverman AD, Chushak YG, Zimlich K, Wolfe M, Thavarajah W, Jewett MC, Lucks JB, Chávez JL. Engineering a Synthetic Dopamine-Responsive Riboswitch for In Vitro Biosensing. ACS Synth Biol 2022; 11:2275-2283. [PMID: 35775197 DOI: 10.1021/acssynbio.1c00560] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The detection of chemicals using natural allosteric transcription factors is a powerful strategy for point-of-use molecular sensing, particularly using fieldable cell-free gene expression (CFE) systems. However, the reliance of detection schemes on characterized protein-based sensors limits the number of measurable analytes. One alternative solution to this issue is to develop new sensors by generating RNA aptamers against the target analyte and then incorporating them directly into a riboswitch scaffold for ligand-inducible genetic control of a reporter protein. However, this strategy has not generated more than a handful of successful portable cell-free molecular sensors. To address this gap, here we convert dopamine-binding aptamers into functional dopamine-sensing riboswitches that regulate gene expression in a freeze-dried CFE reaction. We then develop an assay for direct detection and semi-quantification of dopamine in human urine. We anticipate that this work will be broadly applicable for converting many in vitro-generated RNA aptamers into fieldable molecular diagnostics.
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Affiliation(s)
- Svetlana V Harbaugh
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Adam D Silverman
- Sherlock Biosciences, Boston, Massachusetts 02135, United States
| | - Yaroslav G Chushak
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,Henry M. Jackson Foundation, Dayton, Ohio 45433, United States
| | - Kathryn Zimlich
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,Henry M. Jackson Foundation, Dayton, Ohio 45433, United States
| | - Monica Wolfe
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.,UES, Inc., Dayton, Ohio 45432, United States
| | - Walter Thavarajah
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States.,Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois 60208, United States.,International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Julius B Lucks
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States.,Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois 60208, United States.,International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Jorge L Chávez
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
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17
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Hoetzel J, Suess B. Structural changes in aptamers are essential for synthetic riboswitch engineering. J Mol Biol 2022; 434:167631. [PMID: 35595164 DOI: 10.1016/j.jmb.2022.167631] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/05/2022] [Accepted: 05/07/2022] [Indexed: 11/19/2022]
Abstract
Synthetic riboswitches are powerful tools in synthetic biology in which sensing and execution are consolidated in a single RNA molecule. By using SELEX to select aptamers in vitro, synthetic riboswitches can in theory be engineered against any ligand of choice. Surprisingly, very few in vitro selected aptamers have been used for the engineering of synthetic riboswitches. In-depth studies of these aptamers suggest that the key characteristics of such regulatory active RNAs are their structural switching abilities and their binding dynamics. Conventional SELEX approaches seem to be inadequate to select for these characteristics, which may explain the lack of in vitro selected aptamers suited for engineering of synthetic riboswitches. In this review, we explore the functional principles of synthetic riboswitches, identify key characteristics of regulatory active in vitro selected aptamers and integrate these findings in context with available in vitro selection methods. Based on these insights, we propose to use a combination of capture-SELEX and subsequent functional screening for a more successful in vitro selection of aptamers that can be applied for the engineering of synthetic riboswitches.
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Affiliation(s)
- Janis Hoetzel
- Department of Biology, Technical University of Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany. https://www.twitter.com/J_Hoetzel
| | - Beatrix Suess
- Department of Biology, Technical University of Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany; Center for Synthetic Biology, Technical University of Darmstadt, Germany.
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18
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Zeller MJ, Favorov O, Li K, Nuthanakanti A, Hussein D, Michaud A, Lafontaine DA, Busan S, Serganov A, Aubé J, Weeks KM. SHAPE-enabled fragment-based ligand discovery for RNA. Proc Natl Acad Sci U S A 2022; 119:e2122660119. [PMID: 35561226 PMCID: PMC9171761 DOI: 10.1073/pnas.2122660119] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 04/05/2022] [Indexed: 11/30/2022] Open
Abstract
The transcriptome represents an attractive but underused set of targets for small-molecule ligands. Here, we devise a technology that leverages fragment-based screening and SHAPE-MaP RNA structure probing to discover small-molecule fragments that bind an RNA structure of interest. We identified fragments and cooperatively binding fragment pairs that bind to the thiamine pyrophosphate (TPP) riboswitch with millimolar to micromolar affinities. We then used structure-activity relationship information to efficiently design a linked-fragment ligand, with no resemblance to the native ligand, with high ligand efficiency and druglikeness, that binds to the TPP thiM riboswitch with high nanomolar affinity and that modulates RNA conformation during cotranscriptional folding. Principles from this work are broadly applicable, leveraging cooperativity and multisite binding, for developing high-quality ligands for diverse RNA targets.
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Affiliation(s)
- Meredith J. Zeller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Oleg Favorov
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kelin Li
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Ashok Nuthanakanti
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
| | - Dina Hussein
- Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, J1K 2R1, QC, Canada
| | - Auréliane Michaud
- Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, J1K 2R1, QC, Canada
| | - Daniel A. Lafontaine
- Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, J1K 2R1, QC, Canada
| | - Steven Busan
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Alexander Serganov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
| | - Jeffrey Aubé
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kevin M. Weeks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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19
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Hsu HT, Murata A, Dohno C, Nakatani K, Chang K. Premature translation termination mediated non-ER stress induced ATF6 activation by a ligand-dependent ribosomal frameshifting circuit. Nucleic Acids Res 2022; 50:5369-5383. [PMID: 35511080 PMCID: PMC9122530 DOI: 10.1093/nar/gkac257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 03/29/2022] [Accepted: 04/29/2022] [Indexed: 11/14/2022] Open
Abstract
The −1 programmed ribosomal frameshifting (−1 PRF) has been explored as a gene regulatory circuit for synthetic biology applications. The −1 PRF usually uses an RNA pseudoknot structure as the frameshifting stimulator. Finding a ligand-responsive pseudoknot with efficient −1 PRF activity is time consuming and is becoming a bottleneck for its development. Inserting a guanine to guanine (GG)–mismatch pair in the 5′-stem of a small frameshifting pseudoknot could attenuate −1 PRF activity by reducing stem stability. Thus, a ligand-responsive frameshifting pseudoknot can be built using GG-mismatch–targeting small molecules to restore stem stability. Here, a pseudoknot requiring stem–loop tertiary interactions for potent frameshifting activity was used as the engineering template. This considerably amplified the effect of mismatch destabilization, and led to creation of a mammalian −1 PRF riboswitch module capable of mediating premature translation termination as a synthetic regulatory mode. Application of the synthetic circuit allowed ligand-dependent ATF6N mimic formation for the activation of protein folding–related genes involved in the unfolded protein response without an ER-stress inducing agent. With the availability of mismatch-targeting molecules, the tailored module thus paves the way for various mismatch plug-ins to streamline highly efficient orthogonal ligand-dependent −1 PRF stimulator development in the synthetic biology toolbox.
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Affiliation(s)
- Hsiu-Ting Hsu
- Graduate Institute of Biochemistry, National Chung-Hsing University, Taichung 402, Taiwan
| | - Asako Murata
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Chikara Dohno
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Kazuhiko Nakatani
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - KungYao Chang
- Graduate Institute of Biochemistry, National Chung-Hsing University, Taichung 402, Taiwan
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20
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Synthetic RNA-based post-transcriptional expression control methods and genetic circuits. Adv Drug Deliv Rev 2022; 184:114196. [PMID: 35288218 DOI: 10.1016/j.addr.2022.114196] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/27/2022] [Accepted: 03/08/2022] [Indexed: 12/19/2022]
Abstract
RNA-based synthetic genetic circuits provide an alternative for traditional transcription-based circuits in applications where genomic integration is to be avoided. Incorporating various post-transcriptional control methods into such circuits allows for controlling the behaviour of the circuit through the detection of certain biomolecular inputs or reconstituting defined circuit behaviours, thus manipulating cellular functions. In this review, recent developments of various types of post-transcriptional control methods in mammalian cells are discussed as well as auxiliary components that allow for the creation and development of mRNA-based switches. How such post-transcriptional switches are combined into synthetic circuits as well as their applications in biomedical and preclinical settings are also described. Finally, we examine the challenges that need to be surmounted before RNA-based synthetic circuits can be reliably deployed into clinical settings.
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21
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Tabuchi T, Yokobayashi Y. High-throughput screening of cell-free riboswitches by fluorescence-activated droplet sorting. Nucleic Acids Res 2022; 50:3535-3550. [PMID: 35253887 PMCID: PMC8989549 DOI: 10.1093/nar/gkac152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/15/2022] [Accepted: 02/20/2022] [Indexed: 11/14/2022] Open
Abstract
Cell-free systems that display complex functions without using living cells are emerging as new platforms to test our understanding of biological systems as well as for practical applications such as biosensors and biomanufacturing. Those that use cell-free protein synthesis (CFPS) systems to enable genetically programmed protein synthesis have relied on genetic regulatory components found or engineered in living cells. However, biological constraints such as cell permeability, metabolic stability, and toxicity of signaling molecules prevent development of cell-free devices using living cells even if cell-free systems are not subject to such constraints. Efforts to engineer regulatory components directly in CFPS systems thus far have been based on low-throughput experimental approaches, limiting the availability of basic components to build cell-free systems with diverse functions. Here, we report a high-throughput screening method to engineer cell-free riboswitches that respond to small molecules. Droplet-sorting of riboswitch variants in a CFPS system rapidly identified cell-free riboswitches that respond to compounds that are not amenable to bacterial screening methods. Finally, we used a histamine riboswitch to demonstrate chemical communication between cell-sized droplets.
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Affiliation(s)
- Takeshi Tabuchi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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22
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Eriksson RAE, Nieminen T, Galibert L, Peltola SK, Tikkanen P, Käyhty P, Lesch HP, Ylä-Herttuala S, Airenne KJ. Optimized riboswitch-regulated AAV vector for VEGF-B gene therapy. Front Med (Lausanne) 2022; 9:1052318. [PMID: 36582287 PMCID: PMC9792491 DOI: 10.3389/fmed.2022.1052318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/24/2022] [Indexed: 12/15/2022] Open
Abstract
Gene therapy would greatly benefit from a method to regulate therapeutic gene expression temporally. Riboswitches are small RNA elements that have been studied for their potential use in turning transgene expression on or off by ligand binding. We compared several tetracycline and toyocamycin-inducible ON-riboswitches for a drug responsive transgene expression. The tetracycline-dependent K19 riboswitch showed the best control and we successfully applied it to different transgenes. The induction of gene expression was 6- to 10-fold, dose-dependent, reversible, and occurred within hours after the addition of a clinically relevant tetracycline dose, using either plasmid or adeno-associated virus (AAV) vectors. To enhance the switching capacity, we further optimized the gene cassette to control the expression of a potential therapeutic gene for cardiovascular diseases, VEGF-B. Using two or three riboswitches simultaneously reduced leakiness and improved the dynamic range, and a linker sequence between the riboswitches improved their functionality. The riboswitch function was promoter-independent, but a post-transcriptional WPRE element in the expression cassette reduced its functionality. The optimized construct was a dual riboswitch at the 3' end of the transgene with a 100 bp linker sequence. Our study reveals significant differences in the function of riboswitches and provides important aspects on optimizing expression cassette designs. The findings will benefit further research and development of riboswitches.
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Affiliation(s)
- Reetta A E Eriksson
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland.,A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Tiina Nieminen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | | | | | - Petra Tikkanen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Piia Käyhty
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland.,A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Hanna P Lesch
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Seppo Ylä-Herttuala
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.,Gene Therapy Unit and Research Center, Kuopio University Hospital, Kuopio, Finland
| | - Kari J Airenne
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
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23
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Talap J, Zhao J, Shen M, Song Z, Zhou H, Kang Y, Sun L, Yu L, Zeng S, Cai S. Recent advances in therapeutic nucleic acids and their analytical methods. J Pharm Biomed Anal 2021; 206:114368. [PMID: 34571322 DOI: 10.1016/j.jpba.2021.114368] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 12/11/2022]
Abstract
Therapeutic nucleic acids are various chemically modified RNA or DNA with different functions, which mainly play roles at the gene level. Owing to its accurately targeting at pathogenic genes, nucleic acid based therapeutics have a wide range of application prospects. Recently, the improvement on chemical synthesis and delivery materials accelerated the development of therapeutic nucleic acids rapidly. Up to now, 17 nucleic acid based therapeutics approved by Food and Drug Administration (FDA) or European Medicines Agency (EMA). The development of therapeutics raised higher requirements for analytical methods, both in quality control and in clinical research. The first part of this review introduces different classes of therapeutic nucleic acids, including antisense oligonucleotide (ASO), RNA interference (RNAi) therapy, mRNA, aptamer and other classes which are under research. The second part reviews the therapeutic nucleic acids commercialized from 2019 to now. The third part discusses the analytical methods for nucleic acid based therapeutics, including liquid chromatography-based methods, capillary gel electrophoresis (CGE), hybridization enzyme-linked immunosorbent assay (ELISA) and other infrequently used methods. Finally, the advantages and shortcomings of these methods are summarized, and the future development of analysis methods are prospected.
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Affiliation(s)
- Jadera Talap
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jing Zhao
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao
| | - Minzhe Shen
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Zihan Song
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Hui Zhou
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yu Kang
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Lianli Sun
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Lushan Yu
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Su Zeng
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; Cancer Center of Zhejiang University, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Hangzhou, China.
| | - Sheng Cai
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; Cancer Center of Zhejiang University, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Hangzhou, China.
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24
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Darrah KE, Deiters A. Translational control of gene function through optically regulated nucleic acids. Chem Soc Rev 2021; 50:13253-13267. [PMID: 34739027 DOI: 10.1039/d1cs00257k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Translation of mRNA into protein is one of the most fundamental processes within biological systems. Gene expression is tightly regulated both in space and time, often involving complex signaling or gene regulatory networks, as most prominently observed in embryo development. Thus, studies of gene function require tools with a matching level of external control. Light is an excellent conditional trigger as it is minimally invasive, can be easily tuned in wavelength and amplitude, and can be applied with excellent spatial and temporal resolution. To this end, modification of established oligonucleotide-based technologies with optical control elements, in the form of photocaging groups and photoswitches, has rendered these tools capable of navigating the dynamic regulatory pathways of mRNA translation in cellular and in vivo models. In this review, we discuss the different optochemical approaches used to generate photoresponsive nucleic acids that activate and deactivate gene expression and function at the translational level.
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Affiliation(s)
- Kristie E Darrah
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA.
| | - Alexander Deiters
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA.
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25
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McSweeney MA, Styczynski MP. Effective Use of Linear DNA in Cell-Free Expression Systems. Front Bioeng Biotechnol 2021; 9:715328. [PMID: 34354989 PMCID: PMC8329657 DOI: 10.3389/fbioe.2021.715328] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/06/2021] [Indexed: 12/27/2022] Open
Abstract
Cell-free expression systems (CFEs) are cutting-edge research tools used in the investigation of biological phenomena and the engineering of novel biotechnologies. While CFEs have many benefits over in vivo protein synthesis, one particularly significant advantage is that CFEs allow for gene expression from both plasmid DNA and linear expression templates (LETs). This is an important and impactful advantage because functional LETs can be efficiently synthesized in vitro in a few hours without transformation and cloning, thus expediting genetic circuit prototyping and allowing expression of toxic genes that would be difficult to clone through standard approaches. However, native nucleases present in the crude bacterial lysate (the basis for the most affordable form of CFEs) quickly degrade LETs and limit expression yield. Motivated by the significant benefits of using LETs in lieu of plasmid templates, numerous methods to enhance their stability in lysate-based CFEs have been developed. This review describes approaches to LET stabilization used in CFEs, summarizes the advancements that have come from using LETs with these methods, and identifies future applications and development goals that are likely to be impactful to the field. Collectively, continued improvement of LET-based expression and other linear DNA tools in CFEs will help drive scientific discovery and enable a wide range of applications, from diagnostics to synthetic biology research tools.
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Affiliation(s)
- Megan A McSweeney
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, United States
| | - Mark P Styczynski
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, United States
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26
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Weinberg CE, Olzog VJ, Eckert I, Weinberg Z. Identification of over 200-fold more hairpin ribozymes than previously known in diverse circular RNAs. Nucleic Acids Res 2021; 49:6375-6388. [PMID: 34096583 PMCID: PMC8216279 DOI: 10.1093/nar/gkab454] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 05/12/2021] [Indexed: 11/18/2022] Open
Abstract
Self-cleaving ribozymes are catalytic RNAs that cut themselves at a specific inter-nucleotide linkage. They serve as a model of RNA catalysis, and as an important tool in biotechnology. For most of the nine known structural classes of self-cleaving ribozymes, at least hundreds of examples are known, and some are present in multiple domains of life. By contrast, only four unique examples of the hairpin ribozyme class are known, despite its discovery in 1986. We bioinformatically predicted 941 unique hairpin ribozymes of a different permuted form from the four previously known hairpin ribozymes, and experimentally confirmed several diverse predictions. These results profoundly expand the number of natural hairpin ribozymes, enabling biochemical analysis based on natural sequences, and suggest that a distinct permuted form is more biologically relevant. Moreover, all novel hairpins were discovered in metatranscriptomes. They apparently reside in RNA molecules that vary both in size—from 381 to 5170 nucleotides—and in protein content. The RNA molecules likely replicate as circular single-stranded RNAs, and potentially provide a dramatic increase in diversity of such RNAs. Moreover, these organisms have eluded previous attempts to isolate RNA viruses from metatranscriptomes—suggesting a significant untapped universe of viruses or other organisms hidden within metatranscriptome sequences.
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Affiliation(s)
- Christina E Weinberg
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, 04103 Leipzig, Germany
| | - V Janett Olzog
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, 04103 Leipzig, Germany
| | - Iris Eckert
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107 Leipzig, Germany
| | - Zasha Weinberg
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107 Leipzig, Germany
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27
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Konikkat S, Scribner MR, Eutsey R, Hiller NL, Cooper VS, McManus J. Quantitative mapping of mRNA 3' ends in Pseudomonas aeruginosa reveals a pervasive role for premature 3' end formation in response to azithromycin. PLoS Genet 2021; 17:e1009634. [PMID: 34252072 PMCID: PMC8297930 DOI: 10.1371/journal.pgen.1009634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/22/2021] [Accepted: 06/01/2021] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa produces serious chronic infections in hospitalized patients and immunocompromised individuals, including patients with cystic fibrosis. The molecular mechanisms by which P. aeruginosa responds to antibiotics and other stresses to promote persistent infections may provide new avenues for therapeutic intervention. Azithromycin (AZM), an antibiotic frequently used in cystic fibrosis treatment, is thought to improve clinical outcomes through a number of mechanisms including impaired biofilm growth and quorum sensing (QS). The mechanisms underlying the transcriptional response to AZM remain unclear. Here, we interrogated the P. aeruginosa transcriptional response to AZM using a fast, cost-effective genome-wide approach to quantitate RNA 3’ ends (3pMap). We also identified hundreds of P. aeruginosa genes with high incidence of premature 3’ end formation indicative of riboregulation in their transcript leaders using 3pMap. AZM treatment of planktonic and biofilm cultures alters the expression of hundreds of genes, including those involved in QS, biofilm formation, and virulence. Strikingly, most genes downregulated by AZM in biofilms had increased levels of intragenic 3’ ends indicating premature transcription termination, transcriptional pausing, or accumulation of stable intermediates resulting from the action of nucleases. Reciprocally, AZM reduced premature intragenic 3’ end termini in many upregulated genes. Most notably, reduced termination accompanied robust induction of obgE, a GTPase involved in persister formation in P. aeruginosa. Our results support a model in which AZM-induced changes in 3’ end formation alter the expression of central regulators which in turn impairs the expression of QS, biofilm formation and stress response genes, while upregulating genes associated with persistence. Pseudomonas aeruginosa is a common source of hospital-acquired infections and causes prolonged illness in patients with cystic fibrosis. P. aeruginosa infections are often treated with the macrolide antibiotic azithromycin, which changes the expression of many genes involved in infection. By examining such expression changes at nucleotide resolution, we found azithromycin treatment alters the locations of mRNA 3’ ends suggesting most downregulated genes are subject to premature 3’ end formation. We further identified candidate RNA regulatory elements that P. aeruginosa may use to control gene expression. Our work provides new insights in P. aeruginosa gene regulation and its response to antibiotics.
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Affiliation(s)
- Salini Konikkat
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Michelle R. Scribner
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Rory Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - N. Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Vaughn S. Cooper
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Joel McManus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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28
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Tickner ZJ, Farzan M. Riboswitches for Controlled Expression of Therapeutic Transgenes Delivered by Adeno-Associated Viral Vectors. Pharmaceuticals (Basel) 2021; 14:ph14060554. [PMID: 34200913 PMCID: PMC8230432 DOI: 10.3390/ph14060554] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 11/16/2022] Open
Abstract
Vectors developed from adeno-associated virus (AAV) are powerful tools for in vivo transgene delivery in both humans and animal models, and several AAV-delivered gene therapies are currently approved for clinical use. However, AAV-mediated gene therapy still faces several challenges, including limited vector packaging capacity and the need for a safe, effective method for controlling transgene expression during and after delivery. Riboswitches, RNA elements which control gene expression in response to ligand binding, are attractive candidates for regulating expression of AAV-delivered transgene therapeutics because of their small genomic footprints and non-immunogenicity compared to protein-based expression control systems. In addition, the ligand-sensing aptamer domains of many riboswitches can be exchanged in a modular fashion to allow regulation by a variety of small molecules, proteins, and oligonucleotides. Riboswitches have been used to regulate AAV-delivered transgene therapeutics in animal models, and recently developed screening and selection methods allow rapid isolation of riboswitches with novel ligands and improved performance in mammalian cells. This review discusses the advantages of riboswitches in the context of AAV-delivered gene therapy, the subsets of riboswitch mechanisms which have been shown to function in human cells and animal models, recent progress in riboswitch isolation and optimization, and several examples of AAV-delivered therapeutic systems which might be improved by riboswitch regulation.
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Affiliation(s)
- Zachary J. Tickner
- Department of Immunology and Microbiology, the Scripps Research Institute, Jupiter, FL 33458, USA;
- Correspondence:
| | - Michael Farzan
- Department of Immunology and Microbiology, the Scripps Research Institute, Jupiter, FL 33458, USA;
- Emmune, Inc., Jupiter, FL 33458, USA
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29
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Günzel C, Kühnl F, Arnold K, Findeiß S, Weinberg CE, Stadler PF, Mörl M. Beyond Plug and Pray: Context Sensitivity and in silico Design of Artificial Neomycin Riboswitches. RNA Biol 2021; 18:457-467. [PMID: 32882151 PMCID: PMC7971258 DOI: 10.1080/15476286.2020.1816336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/18/2020] [Accepted: 06/22/2020] [Indexed: 01/05/2023] Open
Abstract
Gene regulation in prokaryotes often depends on RNA elements such as riboswitches or RNA thermometers located in the 5' untranslated region of mRNA. Rearrangements of the RNA structure in response, e.g., to the binding of small molecules or ions control translational initiation or premature termination of transcription and thus mRNA expression. Such structural responses are amenable to computational modelling, making it possible to rationally design synthetic riboswitches for a given aptamer. Starting from an artificial aptamer, we construct the first synthetic transcriptional riboswitches that respond to the antibiotic neomycin. We show that the switching behaviour in vivo critically depends not only on the sequence of the riboswitch itself, but also on its sequence context. We therefore developed in silico methods to predict the impact of the context, making it possible to adapt the design and to rescue non-functional riboswitches. We furthermore analyse the influence of 5' hairpins with varying stability on neomycin riboswitch activity. Our data highlight the limitations of a simple plug-and-play approach in the design of complex genetic circuits and demonstrate that detailed computational models significantly simplify, improve, and automate the design of transcriptional circuits. Our design software is available under a free licence on GitHub (https://github.com/xileF1337/riboswitch_design).
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Affiliation(s)
- Christian Günzel
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, D-04103 Leipzig, Germany
| | - Felix Kühnl
- Bioinformatics Group, Institute of Computer Science, and Interdisciplinary Center for Bioinformatics, Leipzig University, Härtelstraße 16–18, D-04107 Leipzig, Germany
| | - Katharina Arnold
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, D-04103 Leipzig, Germany
| | - Sven Findeiß
- Bioinformatics Group, Institute of Computer Science, and Interdisciplinary Center for Bioinformatics, Leipzig University, Härtelstraße 16–18, D-04107 Leipzig, Germany
| | - Christina E. Weinberg
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, D-04103 Leipzig, Germany
| | - Peter F. Stadler
- Bioinformatics Group, Institute of Computer Science, and Interdisciplinary Center for Bioinformatics, Leipzig University, Härtelstraße 16–18, D-04107 Leipzig, Germany
- Max Planck Institute for Mathematics in the Sciences, Inselstraße Leipzig, D-04103 Leipzig, Germany
- Institute for Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Wien, Austria
- Facultad De Ciencias, Universidad National De Colombia, Sede Bogotá, Colombia
- Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, NM87501, USA
| | - Mario Mörl
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, D-04103 Leipzig, Germany
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30
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Ender A, Etzel M, Hammer S, Findeiß S, Stadler P, Mörl M. Ligand-dependent tRNA processing by a rationally designed RNase P riboswitch. Nucleic Acids Res 2021; 49:1784-1800. [PMID: 33469651 PMCID: PMC7897497 DOI: 10.1093/nar/gkaa1282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 11/29/2022] Open
Abstract
We describe a synthetic riboswitch element that implements a regulatory principle which directly addresses an essential tRNA maturation step. Constructed using a rational in silico design approach, this riboswitch regulates RNase P-catalyzed tRNA 5′-processing by either sequestering or exposing the single-stranded 5′-leader region of the tRNA precursor in response to a ligand. A single base pair in the 5′-leader defines the regulatory potential of the riboswitch both in vitro and in vivo. Our data provide proof for prior postulates on the importance of the structure of the leader region for tRNA maturation. We demonstrate that computational predictions of ligand-dependent structural rearrangements can address individual maturation steps of stable non-coding RNAs, thus making them amenable as promising target for regulatory devices that can be used as functional building blocks in synthetic biology.
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Affiliation(s)
- Anna Ender
- Institute for Biochemistry, Leipzig University, Brüderstr. 34, 04103 Leipzig, Germany
| | - Maja Etzel
- Institute for Biochemistry, Leipzig University, Brüderstr. 34, 04103 Leipzig, Germany
| | - Stefan Hammer
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, Leipzig University, Härtelstr. 16-18, 04107 Leipzig, Germany
| | - Sven Findeiß
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, Leipzig University, Härtelstr. 16-18, 04107 Leipzig, Germany
| | - Peter Stadler
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, Leipzig University, Härtelstr. 16-18, 04107 Leipzig, Germany.,Max Planck Institute for Mathematics in the Science, Inselstr. 22, 04103 Leipzig, Germany.,Institute for Theoretical Chemistry, University of Vienna, Währingerstr. 17, A-1090 Vienna, Austria.,Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
| | - Mario Mörl
- Institute for Biochemistry, Leipzig University, Brüderstr. 34, 04103 Leipzig, Germany
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Chyży P, Kulik M, Re S, Sugita Y, Trylska J. Mutations of N1 Riboswitch Affect its Dynamics and Recognition by Neomycin Through Conformational Selection. Front Mol Biosci 2021; 8:633130. [PMID: 33708793 PMCID: PMC7942488 DOI: 10.3389/fmolb.2021.633130] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/07/2021] [Indexed: 11/13/2022] Open
Abstract
Short, structured fragments of non-coding mRNA may act as molecular switches upon binding specific ligands, regulating the translation of proteins encoded downstream this mRNA sequence. One switch, called riboswitch N1, is regulated by aminoglycosides such as neomycin. Nucleobase mutations in the apical loop, although distant from the binding pocket, significantly affect neomycin affinity and riboswitch regulatory efficiency. To explain this influence, we conducted molecular dynamics simulations using generalized replica exchange with solute tempering (gREST). Translation assay of a reporter protein in a yeast system shows that mutating A17 to G in the riboswitch apical loop reduces 6-fold the translation regulation efficiency of the mutant. Indeed, simulations of the unbound riboswitch show that G17 frequently stacks with base 7, while base 8 is stabilized towards the binding site in a way that it may interfere with the conformational selection mechanism and decrease riboswitch regulatory activity. In the riboswitch complexes, this single-point A to G mutation disrupts a strong hydrogen bond between nucleotides 5 and 17 and, instead, a new hydrogen bond between residue 17 and neomycin is created. This change forces neomycin to occupy a slightly shifted position in the binding pocket, which increases neomycin flexibility. Our simulations of the U14C mutation suggest that the riboswitch complex with neomycin is more stable if cytosine 14 is protonated. A hydrogen bond between the RNA phosphate and protonated cytosine appears as the stabilizing factor. Also, based on the cell-free translation assay and isothermal titration calorimetry experiments, mutations of nucleotides 14 and 15 affect only slightly the riboswitch ability to bind the ligand and its activity. Indeed, the simulation of the unbound U15A mutant suggests conformations preformed for ligand binding, which may explain slightly higher regulatory activity of this mutant. Overall, our results corroborate the in vivo and in vitro experiments on the N1 riboswitch-neomycin system, detail the relationship between nucleobase mutations and RNA dynamics, and reveal the conformations playing the major role in the conformational selection mechanism.
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Affiliation(s)
- Piotr Chyży
- Centre of New Technologies, University of Warsaw, Warsaw, Poland.,Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Marta Kulik
- Centre of New Technologies, University of Warsaw, Warsaw, Poland.,Department of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Suyong Re
- RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan.,National Institutes of Biomedical Innovation, Health and Nutrition, Ibaraki, Japan
| | - Yuji Sugita
- RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan.,RIKEN Cluster for Pioneering Research (CPR), Wako, Japan.,RIKEN Center for Computational Science, Kobe, Japan
| | - Joanna Trylska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
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32
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Drogalis LK, Batey RT. Requirements for efficient ligand-gated co-transcriptional switching in designed variants of the B. subtilis pbuE adenine-responsive riboswitch in E. coli. PLoS One 2020; 15:e0243155. [PMID: 33259551 PMCID: PMC7707468 DOI: 10.1371/journal.pone.0243155] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 11/16/2020] [Indexed: 11/18/2022] Open
Abstract
Riboswitches, generally located in the 5'-leader of bacterial mRNAs, direct expression via a small molecule-dependent structural switch that informs the transcriptional or translational machinery. While the structure and function of riboswitch effector-binding (aptamer) domains have been intensely studied, only recently have the requirements for efficient linkage between small molecule binding and the structural switch in the cellular and co-transcriptional context begun to be actively explored. To address this aspect of riboswitch function, we have performed a structure-guided mutagenic analysis of the B. subtilis pbuE adenine-responsive riboswitch, one of the simplest riboswitches that employs a strand displacement switching mechanism to regulate transcription. Using a cell-based fluorescent protein reporter assay to assess ligand-dependent regulatory activity in E. coli, these studies revealed previously unrecognized features of the riboswitch. Within the aptamer domain, local and long-range conformational dynamics influenced by sequences within helices have a significant effect upon efficient regulatory switching. Sequence features of the expression platform including the pre-aptamer leader sequence, a toehold helix and an RNA polymerase pause site all serve to promote strong ligand-dependent regulation. By optimizing these features, we were able to improve the performance of the B. subtilis pbuE riboswitch in E. coli from 5.6-fold induction of reporter gene expression by the wild type riboswitch to over 120-fold in the top performing designed variant. Together, these data point to sequence and structural features distributed throughout the riboswitch required to strike a balance between rates of ligand binding, transcription and secondary structural switching via a strand exchange mechanism and yield new insights into the design of artificial riboswitches.
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MESH Headings
- Adenine/metabolism
- Aptamers, Nucleotide/chemistry
- Aptamers, Nucleotide/genetics
- Aptamers, Nucleotide/metabolism
- Bacillus subtilis/genetics
- Bacillus subtilis/metabolism
- Escherichia coli K12/genetics
- Genes, Reporter
- Genetic Variation
- Ligands
- Models, Genetic
- Models, Molecular
- Mutagenesis
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- Riboswitch/genetics
- Transcription, Genetic
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Affiliation(s)
- Lea K. Drogalis
- Department of Biochemistry, University of Colorado, Boulder, Colorado, United States of America
| | - Robert T. Batey
- Department of Biochemistry, University of Colorado, Boulder, Colorado, United States of America
- * E-mail:
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33
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Ogawa A, Itoh Y. In Vitro Selection of RNA Aptamers Binding to Nanosized DNA for Constructing Artificial Riboswitches. ACS Synth Biol 2020; 9:2648-2655. [PMID: 33017145 DOI: 10.1021/acssynbio.0c00384] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We here designed an in vitro selection scheme for obtaining an aptamer with which to rationally construct an artificial riboswitch as its component part. In fact, a nanosized DNA-binding aptamer obtained through this scheme allowed us to easily and successfully create eukaryotic riboswitches that upregulate internal ribosome entry site-mediated translation in response to the ligand (nanosized DNA) in wheat germ extract, a eukaryotic cell-free expression system. The induction ratio of the best riboswitch ligand-dose-dependently increased to 21 at 300 μM ligand. This switching efficiency is much higher than that of the same type of riboswitch with a widely used theophylline-binding aptamer, which was in vitro selected without considering its utility for constructing riboswitches. The selection scheme described here would facilitate obtaining various ligand/aptamer pairs suitable for constructing artificial riboswitches, which could serve as elements of synthetic gene circuits in synthetic biology.
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Affiliation(s)
- Atsushi Ogawa
- Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Yu Itoh
- Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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34
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Mehrshahi P, Nguyen GTDT, Gorchs Rovira A, Sayer A, Llavero-Pasquina M, Lim Huei Sin M, Medcalf EJ, Mendoza-Ochoa GI, Scaife MA, Smith AG. Development of Novel Riboswitches for Synthetic Biology in the Green Alga Chlamydomonas. ACS Synth Biol 2020; 9:1406-1417. [PMID: 32496044 PMCID: PMC7309327 DOI: 10.1021/acssynbio.0c00082] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Riboswitches are RNA regulatory elements that bind specific ligands to control gene expression. Because of their modular composition, where a ligand-sensing aptamer domain is combined with an expression platform, riboswitches offer unique tools for synthetic biology applications. Here we took a mutational approach to determine functionally important nucleotide residues in the thiamine pyrophosphate (TPP) riboswitch in the THI4 gene of the model alga Chlamydomonas reinhardtii, allowing us to carry out aptamer swap using THIC aptamers from Chlamydomonas and Arabidopsis thaliana. These chimeric riboswitches displayed a distinct specificity and dynamic range of responses to different ligands. Our studies demonstrate ease of assembly as 5'UTR DNA parts, predictability of output, and utility for controlled production of a high-value compound in Chlamydomonas. The simplicity of riboswitch incorporation in current design platforms will facilitate the generation of genetic circuits to advance synthetic biology and metabolic engineering of microalgae.
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Affiliation(s)
- Payam Mehrshahi
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K
| | - Ginnie Trinh D. T. Nguyen
- Glanbia Performance Nutrition Canada Inc., 3500 Lacey Road, Suite 1200, Downers Grove, Illinois 60515, United States
| | - Aleix Gorchs Rovira
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K
| | - Andrew Sayer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K
| | - Marcel Llavero-Pasquina
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K
| | - Michelle Lim Huei Sin
- John Swire & Sons (H.K.) Ltd. 33/F One Pacific Place, 88 Queensway, Hong Kong, China
| | - Elliot J. Medcalf
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K
| | | | - Mark A. Scaife
- Mara Renewables Corporation, 101A Research Drive, Dartmouth, Nova Scotia B2Y 4T6, Canada
| | - Alison G. Smith
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K
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35
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Rotstan KA, Abdelsayed MM, Passalacqua LFM, Chizzolini F, Sudarshan K, Chamberlin AR, Míšek J, Luptak A. Regulation of mRNA translation by a photoriboswitch. eLife 2020; 9:e51737. [PMID: 32053109 PMCID: PMC7051177 DOI: 10.7554/elife.51737] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 02/12/2020] [Indexed: 12/15/2022] Open
Abstract
Optogenetic tools have revolutionized the study of receptor-mediated processes, but such tools are lacking for RNA-controlled systems. In particular, light-activated regulatory RNAs are needed for spatiotemporal control of gene expression. To fill this gap, we used in vitro selection to isolate a novel riboswitch that selectively binds the trans isoform of a stiff-stilbene (amino-tSS)-a rapidly and reversibly photoisomerizing small molecule. Structural probing revealed that the RNA binds amino-tSS about 100-times stronger than the cis photoisoform (amino-cSS). In vitro and in vivo functional analysis showed that the riboswitch, termed Werewolf-1 (Were-1), inhibits translation of a downstream open reading frame when bound to amino-tSS. Photoisomerization of the ligand with a sub-millisecond pulse of light induced the protein expression. In contrast, amino-cSS supported protein expression, which was inhibited upon photoisomerization to amino-tSS. Reversible photoregulation of gene expression using a genetically encoded RNA will likely facilitate high-resolution spatiotemporal analysis of complex RNA processes.
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Affiliation(s)
- Kelly A Rotstan
- Department of Pharmaceutical Sciences, University of CaliforniaIrvineUnited States
| | - Michael M Abdelsayed
- Department of Molecular Biology and Biochemistry, University of CaliforniaIrvineUnited States
| | - Luiz FM Passalacqua
- Department of Pharmaceutical Sciences, University of CaliforniaIrvineUnited States
| | - Fabio Chizzolini
- Department of Pharmaceutical Sciences, University of CaliforniaIrvineUnited States
| | | | - A Richard Chamberlin
- Department of Pharmaceutical Sciences, University of CaliforniaIrvineUnited States
- Department of Chemistry, University of CaliforniaIrvineUnited States
| | - Jiří Míšek
- Department of Pharmaceutical Sciences, University of CaliforniaIrvineUnited States
- Department of Organic Chemistry, Charles UniversityPragueCzech Republic
| | - Andrej Luptak
- Department of Pharmaceutical Sciences, University of CaliforniaIrvineUnited States
- Department of Molecular Biology and Biochemistry, University of CaliforniaIrvineUnited States
- Department of Chemistry, University of CaliforniaIrvineUnited States
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36
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Mustafina K, Fukunaga K, Yokobayashi Y. Design of Mammalian ON-Riboswitches Based on Tandemly Fused Aptamer and Ribozyme. ACS Synth Biol 2020; 9:19-25. [PMID: 31820936 DOI: 10.1021/acssynbio.9b00371] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Self-cleaving ribozymes engineered to be activated or inhibited by a small molecule binding to an RNA aptamer inserted within a ribozyme (aptazymes) have proven to be useful for controlling gene expression in living cells. In mammalian cells, an aptazyme embedded in the 5' or 3' untranslated region of an mRNA functions as a synthetic riboswitch to chemically regulate gene expression. However, the variety of aptazyme architectures and the ribozyme scaffolds that have been used for mammalian riboswitches has been limited. In particular, fewer synthetic riboswitches that activate gene expression in response to a small molecule (ON-switches) in mammalian cells have been reported compared to OFF-switches. In this work, we developed mammalian riboswitches that function as guanine-activated ON-switches based on a novel aptazyme architecture in which an aptamer and a ribozyme are fused in tandem. The riboswitch performance was optimized by fine-tuning the stability of a critical stem that controls the ribozyme structure and function, yielding switches with ON/OFF ratios greater than 6.0. Our new aptazyme architecture expands the RNA device toolbox for controlling gene expression in mammalian cells.
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Affiliation(s)
- Kamila Mustafina
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Keisuke Fukunaga
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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37
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Henderson CA, Rail CA, Butt LE, Vincent HA, Callaghan AJ. Generation of small molecule-binding RNA arrays and their application to fluorogen-binding RNA aptamers. Methods 2019; 167:39-53. [PMID: 31055072 PMCID: PMC7068705 DOI: 10.1016/j.ymeth.2019.04.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/04/2019] [Accepted: 04/29/2019] [Indexed: 12/23/2022] Open
Abstract
The discovery and engineering of more and more functions of RNA has highlighted the utility of RNA-targeting small molecules. Recently, several fluorogen-binding RNA aptamers have been developed that have been applied to live cell imaging of RNA and metabolites as RNA tags or biosensors, respectively. Although the design and application of these fluorogen-binding RNA aptamer-based devices is straightforward in theory, in practice, careful optimisation is required. For this reason, high throughput in vitro screening techniques, capable of quantifying fluorogen-RNA aptamer interactions, would be beneficial. We recently developed a method for generating functional-RNA arrays and demonstrated that they could be used to detect fluorogen-RNA aptamer interactions. Specifically, we were able to visualise the interaction between malachite green and the malachite green-binding aptamer. Here we expand this study to demonstrate that functional-RNA arrays can be used to quantify fluorogen-aptamer interactions. As proof-of-concept, we provide detailed protocols for the production of malachite green-binding RNA aptamer and DFHBI-binding Spinach RNA aptamer arrays. Furthermore, we discuss the potential utility of the technology to fluorogen-binding RNA aptamers, including application as a molecular biosensor platform. We anticipate that functional-RNA array technology will be beneficial for a wide variety of biological disciplines.
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Affiliation(s)
- Charlotte A Henderson
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Callum A Rail
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Louise E Butt
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Helen A Vincent
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom.
| | - Anastasia J Callaghan
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom.
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38
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Bervoets I, Charlier D. Diversity, versatility and complexity of bacterial gene regulation mechanisms: opportunities and drawbacks for applications in synthetic biology. FEMS Microbiol Rev 2019; 43:304-339. [PMID: 30721976 PMCID: PMC6524683 DOI: 10.1093/femsre/fuz001] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 01/21/2019] [Indexed: 12/15/2022] Open
Abstract
Gene expression occurs in two essential steps: transcription and translation. In bacteria, the two processes are tightly coupled in time and space, and highly regulated. Tight regulation of gene expression is crucial. It limits wasteful consumption of resources and energy, prevents accumulation of potentially growth inhibiting reaction intermediates, and sustains the fitness and potential virulence of the organism in a fluctuating, competitive and frequently stressful environment. Since the onset of studies on regulation of enzyme synthesis, numerous distinct regulatory mechanisms modulating transcription and/or translation have been discovered. Mostly, various regulatory mechanisms operating at different levels in the flow of genetic information are used in combination to control and modulate the expression of a single gene or operon. Here, we provide an extensive overview of the very diverse and versatile bacterial gene regulatory mechanisms with major emphasis on their combined occurrence, intricate intertwinement and versatility. Furthermore, we discuss the potential of well-characterized basal expression and regulatory elements in synthetic biology applications, where they may ensure orthogonal, predictable and tunable expression of (heterologous) target genes and pathways, aiming at a minimal burden for the host.
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Affiliation(s)
- Indra Bervoets
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Daniel Charlier
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
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39
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Kulik M, Mori T, Sugita Y, Trylska J. Molecular mechanisms for dynamic regulation of N1 riboswitch by aminoglycosides. Nucleic Acids Res 2019; 46:9960-9970. [PMID: 30239867 PMCID: PMC6212780 DOI: 10.1093/nar/gky833] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 09/07/2018] [Indexed: 01/14/2023] Open
Abstract
A synthetic riboswitch N1, inserted into the 5'-untranslated mRNA region of yeast, regulates gene expression upon binding ribostamycin and neomycin. Interestingly, a similar aminoglycoside, paromomycin, differing from neomycin by only one substituent (amino versus hydroxyl), also binds to the N1 riboswitch, but without affecting gene expression, despite NMR evidence that the N1 riboswitch binds all aminoglycosides in a similar way. Here, to explore the details of structural dynamics of the aminoglycoside-N1 riboswitch complexes, we applied all-atom molecular dynamics (MD) and temperature replica-exchange MD simulations in explicit solvent. Indeed, we found that ribostamycin and neomycin affect riboswitch dynamics similarly but paromomycin allows for more flexibility because its complex lacks the contact between the distinctive 6' hydroxyl group and the G9 phosphate. Instead, a transient hydrogen bond of 6'-OH with A17 is formed, which partially diminishes interactions between the bulge and apical loop of the riboswitch, likely contributing to riboswitch inactivity. In many ways, the paromomycin complex mimics the conformations, interactions, and Na+ distribution of the free riboswitch. The MD-derived interaction network helps understand why riboswitch activity depends on aminoglycoside type, whereas for another aminoglycoside-binding site, aminoacyl-tRNA site in 16S rRNA, activity is not discriminatory.
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Affiliation(s)
- Marta Kulik
- RIKEN, Hirosawa, Wako City, Saitama 351-0198, Japan.,Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | | | - Yuji Sugita
- RIKEN, Hirosawa, Wako City, Saitama 351-0198, Japan
| | - Joanna Trylska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
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40
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Phillips JO, Butt LE, Henderson CA, Devonshire M, Healy J, Conway SJ, Locker N, Pickford AR, Vincent HA, Callaghan AJ. High-density functional-RNA arrays as a versatile platform for studying RNA-based interactions. Nucleic Acids Res 2019; 46:e86. [PMID: 29846708 PMCID: PMC6101487 DOI: 10.1093/nar/gky410] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 05/02/2018] [Indexed: 12/13/2022] Open
Abstract
We are just beginning to unravel the myriad of interactions in which non-coding RNAs participate. The intricate RNA interactome is the foundation of many biological processes, including bacterial virulence and human disease, and represents unexploited resources for the development of potential therapeutic interventions. However, identifying specific associations of a given RNA from the multitude of possible binding partners within the cell requires robust high-throughput systems for their rapid screening. Here, we present the first demonstration of functional-RNA arrays as a novel platform technology designed for the study of such interactions using immobilized, active RNAs. We have generated high-density RNA arrays by an innovative method involving surface-capture of in vitro transcribed RNAs. This approach has significant advantages over existing technologies, particularly in its versatility in regards to binding partner character. Indeed, proof-of-principle application of RNA arrays to both RNA–small molecule and RNA–RNA pairings is demonstrated, highlighting their potential as a platform technology for mapping RNA-based networks and for pharmaceutical screening. Furthermore, the simplicity of the method supports greater user-accessibility over currently available technologies. We anticipate that functional-RNA arrays will find broad utility in the expanding field of RNA characterization.
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Affiliation(s)
- Jack O Phillips
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Louise E Butt
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Charlotte A Henderson
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Martin Devonshire
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Jess Healy
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Stuart J Conway
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford GU2 7HX, UK
| | - Andrew R Pickford
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Helen A Vincent
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Anastasia J Callaghan
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
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41
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Abstract
Systemic Salmonella enterica infections are a major cause of mortality worldwide and are becoming increasingly untreatable. Recent single-cell data from a mouse model of typhoid fever show that the host immune system actually eradicates many Salmonella cells, while other Salmonella organisms thrive at the same time in the same tissue, causing lethal disease progression. The surviving Salmonella cells have highly heterogeneous metabolism, growth rates, and exposure to various stresses. Emerging evidence suggests that similarly heterogeneous host-pathogen encounters might be a key feature of many infectious diseases. This heterogeneity offers fascinating opportunities for research and application. If we understand the mechanisms that determine the disparate local outcomes, we might be able to develop entirely novel strategies for infection control by broadening successful host antimicrobial attacks and closing permissive niches in which pathogens can thrive. This review describes suitable technologies, a current working model of heterogeneous host-Salmonella interactions, the impact of diverse Salmonella subsets on antimicrobial chemotherapy, and major open questions and challenges.
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42
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Evolving methods for rational de novo design of functional RNA molecules. Methods 2019; 161:54-63. [PMID: 31059832 DOI: 10.1016/j.ymeth.2019.04.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 12/16/2022] Open
Abstract
Artificial RNA molecules with novel functionality have many applications in synthetic biology, pharmacy and white biotechnology. The de novo design of such devices using computational methods and prediction tools is a resource-efficient alternative to experimental screening and selection pipelines. In this review, we describe methods common to many such computational approaches, thoroughly dissect these methods and highlight open questions for the individual steps. Initially, it is essential to investigate the biological target system, the regulatory mechanism that will be exploited, as well as the desired components in order to define design objectives. Subsequent computational design is needed to combine the selected components and to obtain novel functionality. This process can usually be split into constrained sequence sampling, the formulation of an optimization problem and an in silico analysis to narrow down the number of candidates with respect to secondary goals. Finally, experimental analysis is important to check whether the defined design objectives are indeed met in the target environment and detailed characterization experiments should be performed to improve the mechanistic models and detect missing design requirements.
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43
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Nshogozabahizi J, Aubrey K, Ross J, Thakor N. Applications and limitations of regulatory
RNA
elements in synthetic biology and biotechnology. J Appl Microbiol 2019; 127:968-984. [DOI: 10.1111/jam.14270] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 03/09/2019] [Accepted: 03/21/2019] [Indexed: 12/13/2022]
Affiliation(s)
- J.C. Nshogozabahizi
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
| | - K.L. Aubrey
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
| | - J.A. Ross
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
| | - N. Thakor
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
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44
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Dwidar M, Yokobayashi Y. Riboswitch Signal Amplification by Controlling Plasmid Copy Number. ACS Synth Biol 2019; 8:245-250. [PMID: 30682247 DOI: 10.1021/acssynbio.8b00454] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Riboswitches are cis-acting RNA devices in mRNAs that control gene expression in response to chemical inputs. As RNA aptamers that recognize diverse classes of molecules can be isolated by in vitro selection, synthetic riboswitches hold promise for various applications in synthetic biology. One of the major drawbacks of riboswitches, however, is their limited dynamic range. A high level of gene expression in the OFF state (leakage) is also a common problem. To address these challenges, we designed and constructed a dual-riboswitch plasmid in which two genes are controlled by theophylline-activated riboswitches. One riboswitch controls the gene of interest, and another riboswitch controls RepL, a phage-derived replication protein that regulates the plasmid copy number. This single-plasmid system afforded an ON/OFF ratio as high as 3900. Furthermore, we used the system to control CRISPR interference (CRISPRi) targeting endogenous genes, and successfully observed expected phenotypic changes in Escherichia coli.
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Affiliation(s)
- Mohammed Dwidar
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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45
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Norouzi M, Pickford AR, Butt LE, Vincent HA, Callaghan AJ. Application of mRNA Arrays for the Production of mCherry Reporter-Protein Arrays for Quantitative Gene Expression Analysis. ACS Synth Biol 2019; 8:207-215. [PMID: 30682244 DOI: 10.1021/acssynbio.8b00266] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The development of programmable regulators that precisely and predictably control gene expression is a major goal of synthetic biology. Consequently, rapid high-throughput biochemical methods capable of quantitatively analyzing all components of gene expression would be of value in the characterization and optimization of regulator performance. In this study we demonstrate a novel application of RNA arrays, involving the production of reporter-protein arrays, to gene expression analysis. This method enables simultaneous quantification of both the transcription and post-transcription/translation components of gene expression, and it also allows the assessment of the orthogonality of multiple regulators. We use our method to directly compare the performance of a series of previously characterized synthetic post-transcriptional riboregulators, thus demonstrating its utility in the development of synthetic regulatory modules and evaluation of gene expression regulation in general.
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Affiliation(s)
- Masoud Norouzi
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Andrew R. Pickford
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Louise E. Butt
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Helen A. Vincent
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Anastasia J. Callaghan
- School of Biological Sciences and Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
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46
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Rossetti M, Del Grosso E, Ranallo S, Mariottini D, Idili A, Bertucci A, Porchetta A. Programmable RNA-based systems for sensing and diagnostic applications. Anal Bioanal Chem 2019; 411:4293-4302. [PMID: 30734852 DOI: 10.1007/s00216-019-01622-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/08/2019] [Accepted: 01/16/2019] [Indexed: 11/28/2022]
Abstract
The emerging field of RNA nanotechnology harnesses the versatility of RNA molecules to generate nature-inspired systems with programmable structure and functionality. Such methodology has therefore gained appeal in the fields of biosensing and diagnostics, where specific molecular recognition and advanced input/output processing are demanded. The use of RNA modules and components allows for achieving diversity in structure and function, for processing information with molecular precision, and for programming dynamic operations on the grounds of predictable non-covalent interactions. When RNA nanotechnology meets bioanalytical chemistry, sensing of target molecules can be performed by harnessing programmable interactions of RNA modules, advanced field-ready biosensors can be manufactured by interfacing RNA-based devices with supporting portable platforms, and RNA sensors can be engineered to be genetically encoded allowing for real-time imaging of biomolecules in living cells. In this article, we report recent advances in RNA-based sensing technologies and discuss current trends in RNA nanotechnology-enabled biomedical diagnostics. In particular, we describe programmable sensors that leverage modular designs comprising dynamic aptamer-based units, synthetic RNA nanodevices able to perform target-responsive regulation of gene expression, and paper-based sensors incorporating artificial RNA networks. Graphical Abstract ᅟ.
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Affiliation(s)
- Marianna Rossetti
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy
| | - Erica Del Grosso
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy
| | - Simona Ranallo
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy
| | - Davide Mariottini
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy
| | - Andrea Idili
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Alessandro Bertucci
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy. .,Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Alessandro Porchetta
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy.
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47
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Abstract
In bacteria and archaea, small RNAs (sRNAs) regulate complex networks through antisense interactions with target mRNAs in trans, and riboswitches regulate gene expression in cis based on the ability to bind small-molecule ligands. Although our understanding and characterization of these two important regulatory RNA classes is far from complete, these RNA-based mechanisms have proven useful for a wide variety of synthetic biology applications. Besides classic and contemporary applications in the realm of metabolic engineering and orthogonal gene control, this review also covers newer applications of regulatory RNAs as biosensors, logic gates, and tools to determine RNA-RNA interactions. A separate section focuses on critical insights gained and challenges posed by fundamental studies of sRNAs and riboswitches that should aid future development of synthetic regulatory RNAs.
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48
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Abstract
RNA is a versatile biomolecule capable of transferring information, taking on distinct three-dimensional shapes, and reacting to ambient conditions. RNA molecules utilize a wide range of mechanisms to control gene expression. An example of such regulation is riboswitches. Consisting exclusively of RNA, they are able to control important metabolic processes, thus providing an elegant and efficient RNA-only regulation system. Existing across all domains of life, riboswitches appear to represent one of the most highly conserved mechanisms for the regulation of a broad range of biochemical pathways. Through binding of a wide range of small-molecule ligands to their so-called aptamer domain, riboswitches undergo a conformational change in their downstream "expression platform." In consequence, the pattern of gene expression changes, which in turn results in increased or decreased protein production. Riboswitches unite the sensing and transduction of a signal that can directly be coupled to the metabolism of the cell; thus they constitute a very potent regulatory mechanism for many organisms. Highly specific RNA-binding domains not only occur in vivo but can also be evolved by means of the SELEX (systematic evolution of ligands by exponential enrichment) method, which allows in vitro selection of aptamers against almost any ligand. Coupling of these aptamers with an expression platform has led to the development of synthetic riboswitches, a highly active research field of great relevance and immense potential. The aim of this review is to summarize developments in the riboswitch field over the last decade and address key questions of recent research.
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49
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Abstract
Oligonucleotides (ONs) can interfere with biomolecules representing the entire extended central dogma. Antisense gapmer, steric block, splice-switching ONs, and short interfering RNA drugs have been successfully developed. Moreover, antagomirs (antimicroRNAs), microRNA mimics, aptamers, DNA decoys, DNAzymes, synthetic guide strands for CRISPR/Cas, and innate immunity-stimulating ONs are all in clinical trials. DNA-targeting, triplex-forming ONs and strand-invading ONs have made their mark on drug development research, but not yet as medicines. Both design and synthetic nucleic acid chemistry are crucial for achieving biologically active ONs. The dominating modifications are phosphorothioate linkages, base methylation, and numerous 2'-substitutions in the furanose ring, such as 2'-fluoro, O-methyl, or methoxyethyl. Locked nucleic acid and constrained ethyl, a related variant, are bridged forms where the 2'-oxygen connects to the 4'-carbon in the sugar. Phosphorodiamidate morpholino oligomers, carrying a modified heterocyclic backbone ring, have also been commercialized. Delivery remains a major obstacle, but systemic administration and intrathecal infusion are used for treatment of the liver and brain, respectively.
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Affiliation(s)
- C I Edvard Smith
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, SE-141 86 Stockholm, Sweden; .,Stellenbosch Institute for Advanced Study, Wallenberg Research Centre, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Rula Zain
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, SE-141 86 Stockholm, Sweden; .,Department of Clinical Genetics, Centre for Rare Diseases, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
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50
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Page K, Shaffer J, Lin S, Zhang M, Liu JM. Engineering Riboswitches in Vivo Using Dual Genetic Selection and Fluorescence-Activated Cell Sorting. ACS Synth Biol 2018; 7:2000-2006. [PMID: 30119599 DOI: 10.1021/acssynbio.8b00099] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Riboswitches, noncoding RNAs that bind a small molecule effector to control gene expression at the level of transcription or translation, are uniquely suited to meet challenges in synthetic biology. To expand the limited set of existing riboswitches, we developed a riboswitch discovery platform that couples dual genetic selection and fluorescence-activated cell sorting to identify novel riboswitches from a 108 random-sequence library in which the aptamer domain of the ThiM#2 riboswitch was replaced with an N40 sequence. In a proof-of-principle validation, we identified novel riboswitches for the small molecule theophylline. Our best riboswitch (Hit 3-5) displays 2.3-fold activation of downstream gene expression in the presence of theophylline. Random mutagenesis of Hit 3-5, coupled with selections and screens, afforded improved riboswitches displaying nearly 3-fold activation. To the best of our knowledge, this is the first report of in vivo directed evolution of an aptamer domain to generate a functional riboswitch.
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Affiliation(s)
- Katharine Page
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Jeremy Shaffer
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Samuel Lin
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Mark Zhang
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
| | - Jane M. Liu
- Department of Chemistry, Pomona College, 645 N. College Avenue, Claremont, California 91711, United States
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