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Xiao W, Liu G, Chen T, Zhang Y, Lu C. Bifidobacterium bifidum SAM-VI Riboswitch Conformation Change Requires Peripheral Helix Formation. Biomolecules 2024; 14:742. [PMID: 39062457 PMCID: PMC11274715 DOI: 10.3390/biom14070742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Revised: 06/10/2024] [Accepted: 06/21/2024] [Indexed: 07/28/2024] Open
Abstract
The Bifidobacterium bifidum SAM-VI riboswitch undergoes dynamic conformational changes that modulate downstream gene expression. Traditional structural methods such as crystallography capture the bound conformation at high resolution, and additional efforts would reveal details from the dynamic transition. Here, we revealed a transcription-dependent conformation model for Bifidobacterium bifidum SAM-VI riboswitch. In this study, we combine small-angle X-ray scattering, chemical probing, and isothermal titration calorimetry to unveil the ligand-binding properties and conformational changes of the Bifidobacterium bifidum SAM-VI riboswitch and its variants. Our results suggest that the SAM-VI riboswitch contains a pre-organized ligand-binding pocket and stabilizes into the bound conformation upon binding to SAM. Whether the P1 stem formed and variations in length critically influence the conformational dynamics of the SAM-VI riboswitch. Our study provides the basis for artificially engineering the riboswitch by manipulating its peripheral sequences without modifying the SAM-binding core.
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Affiliation(s)
- Wenwen Xiao
- College of Biological and Medical Engineering, Donghua University, Shanghai 201620, China; (W.X.); (T.C.); (Y.Z.)
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China;
| | - Ting Chen
- College of Biological and Medical Engineering, Donghua University, Shanghai 201620, China; (W.X.); (T.C.); (Y.Z.)
| | - Yunlong Zhang
- College of Biological and Medical Engineering, Donghua University, Shanghai 201620, China; (W.X.); (T.C.); (Y.Z.)
| | - Changrui Lu
- College of Biological and Medical Engineering, Donghua University, Shanghai 201620, China; (W.X.); (T.C.); (Y.Z.)
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2
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Olenginski LT, Spradlin SF, Batey RT. Flipping the script: Understanding riboswitches from an alternative perspective. J Biol Chem 2024; 300:105730. [PMID: 38336293 PMCID: PMC10907184 DOI: 10.1016/j.jbc.2024.105730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 01/14/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
Riboswitches are broadly distributed regulatory elements most frequently found in the 5'-leader sequence of bacterial mRNAs that regulate gene expression in response to the binding of a small molecule effector. The occupancy status of the ligand-binding aptamer domain manipulates downstream information in the message that instructs the expression machinery. Currently, there are over 55 validated riboswitch classes, where each class is defined based on the identity of the ligand it binds and/or sequence and structure conservation patterns within the aptamer domain. This classification reflects an "aptamer-centric" perspective that dominates our understanding of riboswitches. In this review, we propose a conceptual framework that groups riboswitches based on the mechanism by which RNA manipulates information directly instructing the expression machinery. This scheme does not replace the established aptamer domain-based classification of riboswitches but rather serves to facilitate hypothesis-driven investigation of riboswitch regulatory mechanisms. Based on current bioinformatic, structural, and biochemical studies of a broad spectrum of riboswitches, we propose three major mechanistic groups: (1) "direct occlusion", (2) "interdomain docking", and (3) "strand exchange". We discuss the defining features of each group, present representative examples of riboswitches from each group, and illustrate how these RNAs couple small molecule binding to gene regulation. While mechanistic studies of the occlusion and docking groups have yielded compelling models for how these riboswitches function, much less is known about strand exchange processes. To conclude, we outline the limitations of our mechanism-based conceptual framework and discuss how critical information within riboswitch expression platforms can inform gene regulation.
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Affiliation(s)
| | | | - Robert T Batey
- Department of Biochemistry, University of Colorado, Boulder, Colorado, USA.
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3
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Watanabe T, Kimura Y, Umeno D. MetJ-Based Mutually Interfering SAM-ON/SAM-OFF Biosensors. ACS Synth Biol 2024; 13:624-633. [PMID: 38286030 DOI: 10.1021/acssynbio.3c00621] [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] [Indexed: 01/31/2024]
Abstract
SAM (S-adenosylmethionine) is an important metabolite that operates as a major donor of methyl groups and is a controller of various physiological processes. Its availability is also believed to be a major bottleneck in the biological production of numerous high-value metabolites. Here, we constructed SAM-sensing systems using MetJ, an SAM-dependent transcriptional regulator, as a core component. SAM is a corepressor of MetJ, which suppresses the MetJ promoter with an increasing cellular concentration of SAM (SAM-OFF sensor). The application of transcriptional interference and evolutionary tuning effectively inverted its response, yielding a SAM-ON sensor (signal increases with increasing SAM concentration). By linking two genes encoding fluorescent protein reporters in such a way that their transcription events interfere with each other's and by placing one of them under the control of MetJ, we could increase the effective signal-to-noise ratio of the SAM sensor while decreasing the batch-to-batch deviation in signal output, likely by canceling out the growth-associated fluctuation in translational resources. By taking the ratio of SAM-ON/SAM-OFF signals and by resetting the default pool size of SAM, we could rapidly identify SAM synthetase (MetK) mutants with increased cellular activity from a random library. The strategy described herein should be widely applicable for identifying activity mutants, which would be otherwise overlooked because of the strong homeostasis of metabolic networks.
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Affiliation(s)
- Taro Watanabe
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan
- Kirin Central Research Institute, Kirin Holdings Company, Limited, 2-26-1, Muraoka-Higashi, Fujisawa 251-8555, Kanagawa, Japan
| | - Yuki Kimura
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Daisuke Umeno
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan
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4
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Wu Y, Zhu L, Zhang Y, Xu W. Multidimensional Applications and Challenges of Riboswitches in Biosensing and Biotherapy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2304852. [PMID: 37658499 DOI: 10.1002/smll.202304852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/15/2023] [Indexed: 09/03/2023]
Abstract
Riboswitches have received significant attention over the last two decades for their multiple functionalities and great potential for applications in various fields. This article highlights and reviews the recent advances in biosensing and biotherapy. These fields involve a wide range of applications, such as food safety detection, environmental monitoring, metabolic engineering, live cell imaging, wearable biosensors, antibacterial drug targets, and gene therapy. The discovery, origin, and optimization of riboswitches are summarized to help readers better understand their multidimensional applications. Finally, this review discusses the multidimensional challenges and development of riboswitches in order to further expand their potential for novel applications.
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Affiliation(s)
- Yifan Wu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Longjiao Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Yangzi Zhang
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Wentao Xu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
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5
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Schroeder GM, Kiliushik D, Jenkins JL, Wedekind JE. Structure and function analysis of a type III preQ 1-I riboswitch from Escherichia coli reveals direct metabolite sensing by the Shine-Dalgarno sequence. J Biol Chem 2023; 299:105208. [PMID: 37660906 PMCID: PMC10622847 DOI: 10.1016/j.jbc.2023.105208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/18/2023] [Accepted: 08/22/2023] [Indexed: 09/05/2023] Open
Abstract
Riboswitches are small noncoding RNAs found primarily in the 5' leader regions of bacterial messenger RNAs where they regulate expression of downstream genes in response to binding one or more cellular metabolites. Such noncoding RNAs are often regulated at the translation level, which is thought to be mediated by the accessibility of the Shine-Dalgarno sequence (SDS) ribosome-binding site. Three classes (I-III) of prequeuosine1 (preQ1)-sensing riboswitches are known that control translation. Class I is divided into three subtypes (types I-III) that have diverse mechanisms of sensing preQ1, which is involved in queuosine biosynthesis. To provide insight into translation control, we determined a 2.30 Å-resolution cocrystal structure of a class I type III preQ1-sensing riboswitch identified in Escherichia coli (Eco) by bioinformatic searches. The Eco riboswitch structure differs from previous preQ1 riboswitch structures because it has the smallest naturally occurring aptamer and the SDS directly contacts the preQ1 metabolite. We validated structural observations using surface plasmon resonance and in vivo gene-expression assays, which showed strong switching in live E. coli. Our results demonstrate that the Eco riboswitch is relatively sensitive to mutations that disrupt noncanonical interactions that form the pseudoknot. In contrast to type II preQ1 riboswitches, a kinetic analysis showed that the type III Eco riboswitch strongly prefers preQ1 over the chemically similar metabolic precursor preQ0. Our results reveal the importance of noncanonical interactions in riboswitch-driven gene regulation and the versatility of the class I preQ1 riboswitch pseudoknot as a metabolite-sensing platform that supports SDS sequestration.
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Affiliation(s)
- Griffin M Schroeder
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Daniil Kiliushik
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Jermaine L Jenkins
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Joseph E Wedekind
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
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6
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Liao TW, Huang L, Wilson TJ, Ganser LR, Lilley DMJ, Ha T. Linking folding dynamics and function of SAM/SAH riboswitches at the single molecule level. Nucleic Acids Res 2023; 51:8957-8969. [PMID: 37522343 PMCID: PMC10516623 DOI: 10.1093/nar/gkad633] [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: 04/19/2023] [Revised: 06/27/2023] [Accepted: 07/18/2023] [Indexed: 08/01/2023] Open
Abstract
Riboswitches are regulatory elements found in bacterial mRNAs that control downstream gene expression through ligand-induced conformational changes. Here, we used single-molecule FRET to map the conformational landscape of the translational SAM/SAH riboswitch and probe how co-transcriptional ligand-induced conformational changes affect its translation regulation function. Riboswitch folding is highly heterogeneous, suggesting a rugged conformational landscape that allows for sampling of the ligand-bound conformation even in the absence of ligand. The addition of ligand shifts the landscape, favoring the ligand-bound conformation. Mutation studies identified a key structural element, the pseudoknot helix, that is crucial for determining ligand-free conformations and their ligand responsiveness. We also investigated ribosomal binding site accessibility under two scenarios: pre-folding and co-transcriptional folding. The regulatory function of the SAM/SAH riboswitch involves kinetically favoring ligand binding, but co-transcriptional folding reduces this preference with a less compact initial conformation that exposes the Shine-Dalgarno sequence and takes min to redistribute to more compact conformations of the pre-folded riboswitch. Such slow equilibration decreases the effective ligand affinity. Overall, our study provides a deeper understanding of the complex folding process and how the riboswitch adapts its folding pattern in response to ligand, modulates ribosome accessibility and the role of co-transcriptional folding in these processes.
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Affiliation(s)
- Ting-Wei Liao
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Lin Huang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Timothy J Wilson
- Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Laura R Ganser
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - David M J Lilley
- Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Howard Hughes Medical Institute, Baltimore, MD, USA
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7
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Chen Z, Chen W, Reheman Z, Jiang H, Wu J, Li X. Genetically encoded RNA-based sensors with Pepper fluorogenic aptamer. Nucleic Acids Res 2023; 51:8322-8336. [PMID: 37486780 PMCID: PMC10484673 DOI: 10.1093/nar/gkad620] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 07/21/2023] [Indexed: 07/26/2023] Open
Abstract
Sensors to measure the abundance and signaling of intracellular molecules are crucial for understanding their physiological functions. Although conventional fluorescent protein-based sensors have been designed, RNA-based sensors are promising imaging tools. Numerous RNA-based sensors have been developed. These sensors typically contain RNA G-quadruplex (RG4) motifs and thus may be suboptimal in living cells. Here we describe RNA-based sensors based on Pepper, a fluorogenic RNA without an RG4 motif. With Pepper, we engineered various sensors for metabolites, synthetic compounds, proteins and metal ions in vitro and in living cells. In addition, these sensors show high activation and selectivity, demonstrating their universality and robustness. In the case of sensors responding to S-adenosylmethionine (SAM), a metabolite produced by methionine adenosyltransferase (MATase), we showed that our sensors exhibited positively correlated fluorescence responding to different SAM levels. Importantly, we revealed the SAM biosynthesis pathway and monitored MATase activity and gene expression spatiotemporally in living individual human cells. Additionally, we constructed a ratiometric SAM sensor to determine the inhibition efficacy of a MATase inhibitor in living cells. Together, these sensors comprising Pepper provide a useful platform for imaging diverse cellular targets and their signaling pathway.
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Affiliation(s)
- Zhenyin Chen
- Beijing Institute of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China
- Department of Pulmonary and Critical Care Medicine, Department of Inflammation and Clinical Allergology, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Chen
- Beijing Institute of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China
- Institute of Cytology and Genetics, the Hengyang Key Laboratory of Cellular Stress Biology, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China
| | - Zhayila Reheman
- Beijing Institute of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Science, Hebei University, Baoding, Hebei 071000, China
| | - Haodong Jiang
- Beijing Institute of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiahui Wu
- Department of Chemistry, University of Massachusetts, Amherst, MA01003, USA
| | - Xing Li
- Beijing Institute of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China
- Department of Pulmonary and Critical Care Medicine, Department of Inflammation and Clinical Allergology, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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8
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Fang M, Li H, Xie X, Wang H, Jiang Y, Li T, Zhang B, Jiang X, Cao Y, Zhang R, Zhang D, Zhao Y, Zhu L, Chen X, Yang Y. Imaging intracellular metabolite and protein changes in live mammalian cells with bright fluorescent RNA-based genetically encoded sensors. Biosens Bioelectron 2023; 235:115411. [PMID: 37236014 DOI: 10.1016/j.bios.2023.115411] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/07/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023]
Abstract
Fluorescent RNA (FR)-based genetically encoded sensors have been engineered to detect various essential metabolites in living systems. However, the unfavorable characteristics of FR impede sensor applications. Here, we describe a strategy for converting Pepper fluorescent RNA into a series of fluorescent sensors to detect their cognate targets both in vitro and in live cells. Compared to previously developed FR-based sensors, Pepper-based sensors exhibited expanded emission of up to 620 nm and markedly improved cellular brightness, allowing robust and real-time monitoring of the pharmacologic-triggered dynamics changes in the intracellular level of S-adenosylmethionine (SAM) and the optogenetic manipulated protein translocation in live mammalian cells. Furthermore, signal amplification in fluorescence imaging of the target was achieved using the CRISPR-display strategy by incorporating a Pepper-based sensor into the sgRNA scaffold. Together, these results demonstrate that Pepper can be readily developed into high-performance FR-based sensors to detect various cellular targets.
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Affiliation(s)
- Mengyue Fang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Huiwen Li
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Xin Xie
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Hui Wang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Ying Jiang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Tianyu Li
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Bibi Zhang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Xin Jiang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Yueyang Cao
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Rui Zhang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Dasheng Zhang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Yuzheng Zhao
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China
| | - Linyong Zhu
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, China
| | - Xianjun Chen
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China.
| | - Yi Yang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, 130 Mei Long Road, Shanghai, 200237, China.
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9
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Xue Y, Li J, Chen D, Zhao X, Hong L, Liu Y. Observation of structural switch in nascent SAM-VI riboswitch during transcription at single-nucleotide and single-molecule resolution. Nat Commun 2023; 14:2320. [PMID: 37087479 PMCID: PMC10122661 DOI: 10.1038/s41467-023-38042-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 04/13/2023] [Indexed: 04/24/2023] Open
Abstract
Growing RNAs fold differently as they are transcribed, which modulates their finally adopted structures. Riboswitches regulate gene expression by structural change, which are sensitive to co-transcriptionally structural biology. Here we develop a strategy to track the structural change of RNAs during transcription at single-nucleotide and single-molecule resolution and use it to monitor individual transcripts of the SAM-VI riboswitch (riboSAM) as transcription proceeds, observing co-existence of five states in riboSAM. We report a bifurcated helix in one newly identified state from NMR and single-molecule FRET (smFRET) results, and its presence directs the translation inhibition in our cellular translation experiments. A model is proposed to illustrate the distinct switch patterns and gene-regulatory outcome of riboSAM when SAM is present or absent. Our strategy enables the precise mapping of RNAs' conformational landscape during transcription, and may combine with detection methods other than smFRET for structural studies of RNAs in general.
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Affiliation(s)
- Yanyan Xue
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jun Li
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Dian Chen
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xizhu Zhao
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Liang Hong
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Shanghai Artificial Intelligence Laboratory, Shanghai, 200232, China.
| | - Yu Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Shanghai Artificial Intelligence Laboratory, Shanghai, 200232, China.
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10
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Werner A. Translational and rotational diffusion of short ribonucleic acids. Biochem Biophys Res Commun 2023; 650:17-20. [PMID: 36764208 DOI: 10.1016/j.bbrc.2023.01.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 02/05/2023]
Abstract
Inevitable precondition for ribonucleic acids to regulate gene expression and to perform gene editing is diffusion. Free three-dimensional translational diffusion velocity of RNA of up to 200 nucleotides could be predicted with high accuracy by the empirical model D = 4.58 10-10 N-0.39 m2s-1. Furthermore, the biological function of ribonucleic acids is determined by rotational diffusion. In the presented work, an empirical model is derived applying atom-level shell-modeling of electron density maps, Dr = 1.62 109 N-1.20 s-1, to predict the rotational diffusion coefficient of short ribonucleic acids based on the polymer size.
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Affiliation(s)
- Arne Werner
- Institute for Biochemistry and Molecular Biology, Department of Chemistry, Faculty of Mathematics, Computer Science and Natural Science, Hamburg University, Germany.
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11
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Xu L, Xiao Y, Zhang J, Fang X. Structural insights into translation regulation by the THF-II riboswitch. Nucleic Acids Res 2023; 51:952-965. [PMID: 36620887 PMCID: PMC9881143 DOI: 10.1093/nar/gkac1257] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 01/10/2023] Open
Abstract
In bacteria, expression of folate-related genes is controlled by the tetrahydrofolate (THF) riboswitch in response to specific binding of THF and its derivatives. Recently, a second class of THF riboswitches, named THF-II, was identified in Gram-negative bacteria, which exhibit distinct architecture from the previously characterized THF-I riboswitches found in Gram-positive bacteria. Here, we present the crystal structures of the ligand-bound THF-II riboswitch from Mesorhizobium loti. These structures exhibit a long rod-like fold stabilized by continuous base pair and base triplet stacking across two helices of P1 and P2 and their interconnecting ligand-bound binding pocket. The pterin moiety of the ligand docks into the binding pocket by forming hydrogen bonds with two highly conserved pyrimidines in J12 and J21, which resembles the hydrogen-bonding pattern at the ligand-binding site FAPK in the THF-I riboswitch. Using small-angle X-ray scattering and isothermal titration calorimetry, we further characterized the riboswitch in solution and reveal that Mg2+ is essential for pre-organization of the binding pocket for efficient ligand binding. RNase H cleavage assay indicates that ligand binding reduces accessibility of the ribosome binding site in the right arm of P1, thus down-regulating the expression of downstream genes. Together, these results provide mechanistic insights into translation regulation by the THF-II riboswitch.
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Affiliation(s)
| | | | - Jie Zhang
- Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China,Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China
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12
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Zheng L, Song Q, Xu X, Shen X, Li C, Li H, Chen H, Ren A. Structure-based insights into recognition and regulation of SAM-sensing riboswitches. SCIENCE CHINA. LIFE SCIENCES 2023; 66:31-50. [PMID: 36459353 DOI: 10.1007/s11427-022-2188-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/17/2022] [Indexed: 12/03/2022]
Abstract
Riboswitches are highly conserved RNA elements that located in the 5'-UTR of mRNAs, which undergo real-time structure conformational change to achieve the regulation of downstream gene expression by sensing their cognate ligands. S-adenosylmethionine (SAM) is a ubiquitous methyl donor for transmethylation reactions in all living organisms. SAM riboswitch is one of the most abundant riboswitches that bind to SAM with high affinity and selectivity, serving as regulatory modules in multiple metabolic pathways. To date, seven SAM-specific riboswitch classes that belong to four families, one SAM/SAH riboswitch and one SAH riboswitch have been identified. Each SAM riboswitch family has a well-organized tertiary core scaffold to support their unique ligand-specific binding pocket. In this review, we summarize the current research progress on the distribution, structure, ligand recognition and gene regulation mechanism of these SAM-related riboswitch families, and further discuss their evolutionary prospects and potential applications.
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Affiliation(s)
- Luqian Zheng
- Department of Gastroenterology, Department of Cardiology of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.,The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, 518033, China
| | - Qianqian Song
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Xiaochen Xu
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Xin Shen
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Chunyan Li
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Hongcheng Li
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Hao Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Aiming Ren
- Department of Gastroenterology, Department of Cardiology of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China. .,Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.
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13
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Vallina NS, Geary C, Jepsen M, Andersen ES. Computer-Aided Design and Production of RNA Origami as Protein Scaffolds and Biosensors. Methods Mol Biol 2023; 2639:51-67. [PMID: 37166710 DOI: 10.1007/978-1-0716-3028-0_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
RNA nanotechnology is able to take advantage of the modularity of RNA to build a wide variety of structures and functional devices from a common set of structural modules. The RNA origami architecture harnesses the property of RNA to fold as it is being enzymatically synthesized by the RNA polymerase and enables the design of single-stranded devices that integrate multiple structural and functional RNA motifs. Here, we provide detailed procedures on how to design and characterize RNA origami structures. The process is illustrated by two examples: one that forms lattices and another example that acts as biosensors.
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Affiliation(s)
| | - Cody Geary
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Mette Jepsen
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
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14
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Chen J, Zeng Q, Wang W, Sun H, Hu G. Decoding the Identification Mechanism of an SAM-III Riboswitch on Ligands through Multiple Independent Gaussian-Accelerated Molecular Dynamics Simulations. J Chem Inf Model 2022; 62:6118-6132. [PMID: 36440874 DOI: 10.1021/acs.jcim.2c00961] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
S-Adenosyl-l-methionine (SAM)-responsive riboswitches play a central role in the regulation of bacterial gene expression at the level of transcription attenuation or translation inhibition. In this study, multiple independent Gaussian-accelerated molecular dynamics simulations were performed to decipher the identification mechanisms of SAM-III (SMK) on ligands SAM, SAH, and EEM. The results reveal that ligand binding highly affects the structural flexibility, internal dynamics, and conformational changes of SAM-III. The dynamic analysis shows that helices P3 and P4 as well as two junctions J23 and J24 of SAM-III are highly susceptible to ligand binding. Analyses of free energy landscapes suggest that ligand binding induces different free energy profiles of SAM-III, which leads to the difference in identification sites of SAM-III on ligands. The information on ligand-nucleotide interactions not only uncovers that the π-π, cation-π, and hydrogen bonding interactions drive identification of SAM-III on the three ligands but also reveals that different electrostatic properties of SAM, SAH, and EEM alter the active sites of SAM-III. Meanwhile, the results also verify that the adenine group of SAM, SAH, and EEM is well recognized by conserved nucleotides G7, A29, U37, A38, and G48. We expect that this study can provide useful information for understanding the applications of SAM-III in chemical, synthetic RNA biology, and biomedical fields.
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Affiliation(s)
- Jianzhong Chen
- School of Science, Shandong Jiaotong University, Jinan250357, China
| | - Qingkai Zeng
- School of Science, Shandong Jiaotong University, Jinan250357, China
| | - Wei Wang
- School of Science, Shandong Jiaotong University, Jinan250357, China
| | - Haibo Sun
- School of Science, Shandong Jiaotong University, Jinan250357, China
| | - Guodong Hu
- Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou253023, China
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15
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Arney JW, Weeks KM. RNA-Ligand Interactions Quantified by Surface Plasmon Resonance with Reference Subtraction. Biochemistry 2022; 61:1625-1632. [PMID: 35802500 PMCID: PMC9357220 DOI: 10.1021/acs.biochem.2c00177] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structured RNAs bind ligands and are attractive targets for small-molecule drugs. A wide variety of analytical methods have been used to characterize RNA-ligand interactions, but our experience is that most have significant limitations in terms of material requirements and applicability to complex RNAs. Surface plasmon resonance (SPR) potentially overcomes these limitations, but we find that the standard experimental framework measures notable nonspecific electrostatic-mediated interactions, frustrating analysis of weak RNA binders. SPR measurements are typically quantified relative to a non-target reference channel. Here, we show that referencing to a channel containing a non-binding control RNA enables subtraction of nonspecific binding contributions, allowing measurements of accurate and specific binding affinities. We validated this approach for small-molecule binders of two riboswitch RNAs with affinities ranging from nanomolar to millimolar, including low-molecular-mass fragment ligands. SPR implemented with reference subtraction reliably discriminates specific from nonspecific binding, uses RNA and ligand material efficiently, and enables rapid exploration of the ligand-binding landscape for RNA targets.
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Affiliation(s)
- J. Winston Arney
- Department of Chemistry, University of North Carolina, Chapel Hill, NC
27599-3290
| | - Kevin M. Weeks
- Department of Chemistry, University of North Carolina, Chapel Hill, NC
27599-3290
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16
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Liu XH, Li BR, Ying ZM, Tang LJ, Wang F, Jiang JH. Small-Molecule-Mediated Split-Aptamer Assembly for Inducible CRISPR-dCas9 Transcription Activation. ACS Chem Biol 2022; 17:1769-1777. [PMID: 35700146 DOI: 10.1021/acschembio.2c00101] [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: 11/28/2022]
Abstract
Inducible CRISPR-dCas9 transcription system has become a powerful tool for transcription regulation and sensing. Here, we develop a new concept of small-molecule-mediated split-aptamer assembly for inducible CRISPR-dCas9 transcription activation, allowing quantitative detection and imaging of S-adenosyl methionine (SAM) in live cells. This inducible transcription system is designed by integrating one fragment of a split SAM aptamer to guide RNA (gRNA) and the other to MS2 arrays. SAM-mediated reassembly of the split fragments recruits an MCP-fused transcription activator to the gRNA-dCas9 complex, activating the expression of a near-infrared fluorescent protein for imaging. We demonstrate that this inducible transcription system achieves quantitative detection of SAM with high sensitivity in live cells. Our system shows that methionine adenosyltransferase 1A (MAT1A) and MAT2A can both catalyze SAM production in live cells and the SAM levels in cancer cells can be increased via upregulation of MAT1A mRNA by epigenetic inhibitors. This split-aptamer assembly strategy could afford a new approach for controlling the CRISPR-dCas9 system, enabling conditional transcription regulation in response to endogenous metabolites in live cells.
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Affiliation(s)
- Xiao-Han Liu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Bang-Rui Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Zhan-Ming Ying
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Li-Juan Tang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Fenglin Wang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Jian-Hui Jiang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
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17
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Zhang M, Liu G, Zhang Y, Chen T, Feng S, Cai R, Lu C. The Second Class of Tetrahydrofolate (THF-II) Riboswitches Recognizes the Tetrahydrofolic Acid Ligand via Local Conformation Changes. Int J Mol Sci 2022; 23:ijms23115903. [PMID: 35682583 PMCID: PMC9180208 DOI: 10.3390/ijms23115903] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/02/2022] [Accepted: 05/06/2022] [Indexed: 02/05/2023] Open
Abstract
Riboswitches are regulatory noncoding RNAs found in bacteria, fungi and plants, that modulate gene expressions through structural changes in response to ligand binding. Understanding how ligands interact with riboswitches in solution can shed light on the molecular mechanisms of this ancient regulators. Previous studies showed that riboswitches undergo global conformation changes in response to ligand binding to relay information. Here, we report conformation switching models of the recently discovered tetrahydrofolic acid-responsive second class of tetrahydrofolate (THF-II) riboswitches in response to ligand binding. Using a combination of selective 2′-hydroxyl acylation, analyzed by primer extension (SHAPE) assay, 3D modeling and small-angle X-ray scattering (SAXS), we found that the ligand specifically recognizes and reshapes the THF-II riboswitch loop regions, but does not affect the stability of the P3 helix. Our results show that the THF-II riboswitch undergoes only local conformation changes in response to ligand binding, rearranging the Loop1-P3-Loop2 region and rotating Loop1 from a ~120° angle to a ~75° angle. This distinct conformation changes suggest a unique regulatory mechanism of the THF-II riboswitch, previously unseen in other riboswitches. Our findings may contribute to the fields of RNA sensors and drug design.
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Affiliation(s)
- Minmin Zhang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China; (M.Z.); (Y.Z.); (T.C.); (S.F.)
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China;
| | - Yunlong Zhang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China; (M.Z.); (Y.Z.); (T.C.); (S.F.)
| | - Ting Chen
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China; (M.Z.); (Y.Z.); (T.C.); (S.F.)
| | - Shanshan Feng
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China; (M.Z.); (Y.Z.); (T.C.); (S.F.)
| | - Rujie Cai
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
- Correspondence: (R.C.); (C.L.); Tel.: +86-21-6779-2740 (C.L.)
| | - Changrui Lu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China; (M.Z.); (Y.Z.); (T.C.); (S.F.)
- Correspondence: (R.C.); (C.L.); Tel.: +86-21-6779-2740 (C.L.)
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18
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Dey SK, Filonov GS, Olarerin-George AO, Jackson BT, Finley LWS, Jaffrey SR. Repurposing an adenine riboswitch into a fluorogenic imaging and sensing tag. Nat Chem Biol 2022; 18:180-190. [PMID: 34937909 PMCID: PMC8967656 DOI: 10.1038/s41589-021-00925-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/18/2021] [Indexed: 02/02/2023]
Abstract
Fluorogenic RNA aptamers are used to genetically encode fluorescent RNA and to construct RNA-based metabolite sensors. Unlike naturally occurring aptamers that efficiently fold and undergo metabolite-induced conformational changes, fluorogenic aptamers can exhibit poor folding, which limits their cellular fluorescence. To overcome this, we evolved a naturally occurring well-folded adenine riboswitch into a fluorogenic aptamer. We generated a library of roughly 1015 adenine aptamer-like RNAs in which the adenine-binding pocket was randomized for both size and sequence, and selected Squash, which binds and activates the fluorescence of green fluorescent protein-like fluorophores. Squash exhibits markedly improved in-cell folding and highly efficient metabolite-dependent folding when fused to a S-adenosylmethionine (SAM)-binding aptamer. A Squash-based ratiometric sensor achieved quantitative SAM measurements, revealed cell-to-cell heterogeneity in SAM levels and revealed metabolic origins of SAM. These studies show that the efficient folding of naturally occurring aptamers can be exploited to engineer well-folded cell-compatible fluorogenic aptamers and devices.
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Affiliation(s)
- Sourav Kumar Dey
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY, USA
| | - Grigory S. Filonov
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY, USA.,Present address: Sartorius, Ann Arbor, Michigan, USA
| | | | - Benjamin T. Jackson
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Lydia W. S. Finley
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Samie R. Jaffrey
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY, USA.,
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19
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Moon JD, Wu J, Dey SK, Litke JL, Li X, Kim H, Jaffrey SR. Naturally occurring three-way junctions can be repurposed as genetically encoded RNA-based sensors. Cell Chem Biol 2021; 28:1569-1580.e4. [PMID: 34010626 PMCID: PMC8573057 DOI: 10.1016/j.chembiol.2021.04.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/28/2021] [Accepted: 04/26/2021] [Indexed: 11/28/2022]
Abstract
Small molecules can be imaged in living cells using biosensors composed of RNA. However, RNA-based devices are difficult to design. Here, we describe a versatile platform for designing RNA-based fluorescent small-molecule sensors using naturally occurring highly stable three-way junction RNAs. We show that ligand-binding aptamers and fluorogenic aptamers can be inserted into three-way junctions and connected in a way that enables the three-way junction to function as a small-molecule-regulated fluorescent sensor in vitro and in cells. The sensors are designed so that the interhelical stabilizing interactions in the three-way junction are only induced upon ligand binding. We use these RNA-based devices to measure the dynamics of S-adenosylmethionine levels in mammalian cells in real time. We show that this strategy is compatible with diverse metabolite-binding RNA aptamers, fluorogenic aptamers, and three-way junctions. Overall, these data demonstrate a versatile method for readily generating RNA devices that function in living cells.
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Affiliation(s)
- Jared D Moon
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
| | - Jiahui Wu
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Sourav K Dey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Jacob L Litke
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Xing Li
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Hyaeyeong Kim
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA.
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20
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Piña MDLN, Frontera A, Bauza A. Charge Assisted S/Se Chalcogen Bonds in SAM Riboswitches: A Combined PDB and ab Initio Study. ACS Chem Biol 2021; 16:1701-1708. [PMID: 34427431 PMCID: PMC8525861 DOI: 10.1021/acschembio.1c00417] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
In this study, we provide experimental
(Protein Data Bank (PDB)
inspection) and theoretical (RI-MP2/def2-TZVP level of theory) evidence
of the involvement of charge assisted chalcogen bonding (ChB) interactions
in the recognition and folding mechanisms of S-adenosylmethionine
(SAM) riboswitches. Concretely, an initial PDB search revealed several
examples where ChBs between S-adenosyl methionine (SAM)/adenosyl selenomethionine
(EEM) molecules and uracil (U) bases belonging to RNA take place.
While these interactions are usually described as a merely Coulombic
attraction between the positively charged S/Se group and RNA, theoretical
calculations indicated that the σ holes of S and Se are involved.
Moreover, computational models shed light on the strength and directionality
properties of the interaction, which was also further characterized
from a charge-density perspective using Bader’s “Atoms
in Molecules” (AIM) theory, Non-Covalent Interaction plot (NCIplot)
visual index, and Natural Bonding Orbital (NBO) analyses. As far as
our knowledge extends, this is the first time that ChBs in SAM–RNA
complexes have been systematically analyzed, and we believe the results
might be useful for scientists working in the field of RNA engineering
and chemical biology as well as to increase the visibility of the
interaction among the biological community.
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Affiliation(s)
- María de las Nieves Piña
- Department of Chemistry, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma (Baleares), Spain
| | - Antonio Frontera
- Department of Chemistry, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma (Baleares), Spain
| | - Antonio Bauza
- Department of Chemistry, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma (Baleares), Spain
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21
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Ariza-Mateos A, Nuthanakanti A, Serganov A. Riboswitch Mechanisms: New Tricks for an Old Dog. BIOCHEMISTRY (MOSCOW) 2021; 86:962-975. [PMID: 34488573 DOI: 10.1134/s0006297921080071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Discovered almost twenty years ago, riboswitches turned out to be one of the most common regulatory systems in bacteria, with representatives found in eukaryotes and archaea. Unlike many other regulatory elements, riboswitches are entirely composed of RNA and capable of modulating expression of genes by direct binding of small cellular molecules. While bacterial riboswitches had been initially thought to control production of enzymes and transporters associated with small organic molecules via feedback regulatory circuits, later findings identified riboswitches directing expression of a wide range of genes and responding to various classes of molecules, including ions, signaling molecules, and others. The 5'-untranslated mRNA regions host a vast majority of riboswitches, which modulate transcription or translation of downstream genes through conformational rearrangements in the ligand-sensing domains and adjacent expression-controlling platforms. Over years, the repertoire of regulatory mechanisms employed by riboswitches has greatly expanded; most recent studies have highlighted the importance of alternative mechanisms, such as RNA degradation, for the riboswitch-mediated genetic circuits. This review discusses the plethora of bacterial riboswitch mechanisms and illustrates how riboswitches utilize different features and approaches to elicit various regulatory responses.
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Affiliation(s)
- Ascensión Ariza-Mateos
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Ashok Nuthanakanti
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Alexander Serganov
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA.
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22
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Wilson TJ, Lilley DMJ. The potential versatility of RNA catalysis. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1651. [PMID: 33949113 DOI: 10.1002/wrna.1651] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 01/21/2023]
Abstract
It is commonly thought that in the early development of life on this planet RNA would have acted both as a store of genetic information and as a catalyst. While a number of RNA enzymes are known in contemporary cells, they are largely confined to phosphoryl transfer reactions, whereas an RNA based metabolism would have required a much greater chemical diversity of catalysis. Here we discuss how RNA might catalyze a wider variety of chemistries, and particularly how information gleaned from riboswitches could suggest how ribozymes might recruit coenzymes to expand their chemical range. We ask how we might seek such activities in modern biology. This article is categorized under: RNA-Based Catalysis > Miscellaneous RNA-Catalyzed Reactions Regulatory RNAs/RNAi/Riboswitches > Riboswitches RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry.
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Affiliation(s)
- Timothy J Wilson
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee, UK
| | - David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee, UK
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23
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Liu Y, Yuan H, Ding D, Dong H, Wang Q, Zhang D. Establishment of a Biosensor-based High-Throughput Screening Platform for Tryptophan Overproduction. ACS Synth Biol 2021; 10:1373-1383. [PMID: 34081459 DOI: 10.1021/acssynbio.0c00647] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
With the flexibility to fold into complex structures, RNA is well-suited to act as a cellular sensor to recognize environmental fluctuations and respond to changes by regulating the corresponding genes. In this study, we established a high-throughput screening platform to screen tryptophan high-producing strains from a large repertoire of candidate strains. This platform consists of a tryptophan-specific aptamer-based biosensor and fluorescence-activated droplet sorting technology. One mutant strain, with a 165.9% increase in Trp titer compared with the parental strain, was successfully screened from a random mutagenesis library. Sequencing results revealed that a total of 10 single-nucleotide polymorphisms were discovered in the genome of the mutant strain, among which CRP(T29K) was proven to significantly increase Trp production through improving the strain's tolerance of the harsh environment during the stationary phase of the fermentation process. Our results indicate that this strategy has great potential for improving the production of other amino acids in Escherichia coli.
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Affiliation(s)
- Yongfei Liu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Engineering Laboratory for Industrial Enzymes, Tianjin 300308, China
| | - Huiling Yuan
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Engineering Laboratory for Industrial Enzymes, Tianjin 300308, China
| | - Dongqin Ding
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Engineering Laboratory for Industrial Enzymes, Tianjin 300308, China
| | - Huina Dong
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Engineering Laboratory for Industrial Enzymes, Tianjin 300308, China
| | - Qinhong Wang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Engineering Laboratory for Industrial Enzymes, Tianjin 300308, China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Engineering Laboratory for Industrial Enzymes, Tianjin 300308, China
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24
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Bendre AD, Peters PJ, Kumar J. Recent Insights into the Structure and Function of Mycobacterial Membrane Proteins Facilitated by Cryo-EM. J Membr Biol 2021; 254:321-341. [PMID: 33954837 PMCID: PMC8099146 DOI: 10.1007/s00232-021-00179-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 03/23/2021] [Indexed: 12/26/2022]
Abstract
Mycobacterium tuberculosis (Mtb) is one of the deadliest pathogens encountered by humanity. Over the decades, its characteristic membrane organization and composition have been understood. However, there is still limited structural information and mechanistic understanding of the constituent membrane proteins critical for drug discovery pipelines. Recent advances in single-particle cryo-electron microscopy and cryo-electron tomography have provided the much-needed impetus towards structure determination of several vital Mtb membrane proteins whose structures were inaccessible via X-ray crystallography and NMR. Important insights into membrane composition and organization have been gained via a combination of electron tomography and biochemical and biophysical assays. In addition, till the time of writing this review, 75 new structures of various Mtb proteins have been reported via single-particle cryo-EM. The information obtained from these structures has improved our understanding of the mechanisms of action of these proteins and the physiological pathways they are associated with. These structures have opened avenues for structure-based drug design and vaccine discovery programs that might help achieve global-TB control. This review describes the structural features of selected membrane proteins (type VII secretion systems, Rv1819c, Arabinosyltransferase, Fatty Acid Synthase, F-type ATP synthase, respiratory supercomplex, ClpP1P2 protease, ClpB disaggregase and SAM riboswitch), their involvement in physiological pathways, and possible use as a drug target. Tuberculosis is a deadly disease caused by Mycobacterium tuberculosis. The Cryo-EM and tomography have simplified the understanding of the mycobacterial membrane organization. Some proteins are located in the plasma membrane; some span the entire envelope, while some, like MspA, are located in the mycomembrane. Cryo-EM has made the study of such membrane proteins feasible.
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Affiliation(s)
- Ameya D Bendre
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University Campus, Ganeshkhind, Pune, Maharashtra, 411007, India
| | - Peter J Peters
- The Maastricht Multimodal Molecular Imaging Institute (M4I), Division of Nanoscopy, Maastricht University, Maastricht, The Netherlands
| | - Janesh Kumar
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University Campus, Ganeshkhind, Pune, Maharashtra, 411007, India.
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25
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Abstract
Biocatalysis is dominated by protein enzymes, and only a few classes of ribozymes are known to contribute to the task of promoting biochemical transformations. The RNA World theory encompasses the notion that earlier forms of life made use of a much greater diversity of ribozymes and other functional RNAs to guide complex metabolic states long before proteins had emerged in evolution. In recent years, the discoveries of various classes of ribozymes, riboswitches, and other noncoding RNAs in bacteria have provided additional support for the hypothesis that RNA molecules indeed have the catalytic competence to promote diverse chemical reactions without the aid of protein enzymes. Herein, some of the most striking observations made from examinations of natural riboswitches that bind small ligands are highlighted and used as a basis to imagine the characteristics and functions of long-extinct ribozymes from the RNA World.
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Affiliation(s)
- Ronald R. Breaker
- Department of Molecular, Cellular and Developmental Biology, Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Department of Chemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520, United States
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26
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Huang L, Liao TW, Wang J, Ha T, Lilley DMJ. Crystal structure and ligand-induced folding of the SAM/SAH riboswitch. Nucleic Acids Res 2020; 48:7545-7556. [PMID: 32520325 PMCID: PMC7367207 DOI: 10.1093/nar/gkaa493] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/25/2020] [Accepted: 05/30/2020] [Indexed: 01/09/2023] Open
Abstract
While most SAM riboswitches strongly discriminate between SAM and SAH, the SAM/SAH riboswitch responds to both ligands with similar apparent affinities. We have determined crystal structures of the SAM/SAH riboswitch bound to SAH, SAM and other variant ligands at high resolution. The riboswitch forms an H-type pseudoknot structure with coaxial alignment of the stem–loop helix (P1) and the pseudoknot helix (PK). An additional three base pairs form at the non-open end of P1, and the ligand is bound at the interface between the P1 extension and the PK helix. The adenine nucleobase is stacked into the helix and forms a trans Hoogsteen–Watson–Crick base pair with a uridine, thus becoming an integral part of the helical structure. The majority of the specific interactions are formed with the adenosine. The methionine or homocysteine chain lies in the groove making a single hydrogen bond, and there is no discrimination between the sulfonium of SAM or the thioether of SAH. Single-molecule FRET analysis reveals that the riboswitch exists in two distinct conformations, and that addition of SAM or SAH shifts the population into a stable state that likely corresponds to the form observed in the crystal. A model for translational regulation is presented whereby in the absence of ligand the riboswitch is largely unfolded, lacking the PK helix so that translation can be initiated at the ribosome binding site. But the presence of ligand stabilizes the folded conformation that includes the PK helix, so occluding the ribosome binding site and thus preventing the initiation of translation.
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Affiliation(s)
- Lin Huang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China.,RNA Biomedical Institute, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China.,Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | | | - Jia Wang
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Taekjip Ha
- Department of Biophysics.,Department of Biophysics and Biophysical Chemistry.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.,Howard Hughes Medical Institute, Baltimore, MD, USA
| | - David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
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27
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Huang L, Wang J, Lilley DMJ. Structure and ligand binding of the ADP-binding domain of the NAD + riboswitch. RNA (NEW YORK, N.Y.) 2020; 26:878-887. [PMID: 32295864 PMCID: PMC7297122 DOI: 10.1261/rna.074898.120] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/22/2020] [Indexed: 06/02/2023]
Abstract
The nadA motif is the first known NAD+-dependent riboswitch, comprising two similar tandem bulged stem-loop structures. We have determined the structure of the 5' domain 1 of the riboswitch. It has three coaxial helical segments, separated by an ACANCCCC bulge and by an internal loop, with a tertiary contact between them that includes two C:G base pairs. We have determined the structure with a number of ligands related to NADH, but in each case only the ADP moiety is observed. The adenosine adopts an anti conformation, forms multiple hydrogen bonds across the width of the sugar edge of the penultimate C:G base pair of the helix preceding the bulge, and the observed contacts have been confirmed by mutagenesis and calorimetry. Two divalent metal ions play a key structural role at the narrow neck of the bulge. One makes direct bonding contacts to the diphosphate moiety, locking it into position. Thus the nucleobase, ribose, and phosphate groups of the ADP moiety are all specifically recognized by the RNA. The NAD+ riboswitch is modular. Domain 1 is an ADP binding domain that may be ancient and could potentially be used in combination with other ligand binding motifs such as CoA.
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Affiliation(s)
- Lin Huang
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Jia Wang
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, United Kingdom
| | - David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, United Kingdom
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28
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Endoh T, Sugimoto N. Signaling Aptamer Optimization through Selection Using RNA-Capturing Microsphere Particles. Anal Chem 2020; 92:7955-7963. [PMID: 32363852 DOI: 10.1021/acs.analchem.0c01338] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An RNA signaling aptamer is composed of two units: a sensing aptamer that binds the input target molecule and a working aptamer that binds the output target molecule to result in a detectable signal. A conformational change of the signaling aptamer that induces an allosteric interaction with the output target molecule in response to the input target molecule depends on a junction region, which connects the two aptamer units. Efficient and effective optimization of the junction region remains a technical challenge. In this study, we demonstrate a simple strategy for optimizing the junction region through functional RNA selection using RNA-capturing microsphere particles. From approximately 0.2 million sequence variants, a signaling aptamer that enabled intracellular detection of S-adenosyl methionine with a high signal-to-noise ratio, which is approximately 2-fold higher relative fluorescence increment compared to the previously reported signaling aptamer, was obtained after single round of selection. The technology demonstrated here can be used to select RNA sequences that carry out specific functions in response to particular stimuli.
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Affiliation(s)
- Tamaki Endoh
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe 650-0047, Japan
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe 650-0047, Japan.,Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe 650-0047, Japan
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29
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Alaidi O, Aboul‐ela F. Statistical mechanical prediction of ligand perturbation to RNA secondary structure and application to riboswitches. J Comput Chem 2020; 41:1521-1537. [DOI: 10.1002/jcc.26195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 01/03/2020] [Accepted: 03/09/2020] [Indexed: 02/04/2023]
Affiliation(s)
- Osama Alaidi
- Biocomplexity for Research and Consulting Cairo Egypt
| | - Fareed Aboul‐ela
- Center for X‐Ray Determination of the Structure of MatterZewail City of Science and Technology Giza Egypt
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30
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Sun A, Gasser C, Li F, Chen H, Mair S, Krasheninina O, Micura R, Ren A. SAM-VI riboswitch structure and signature for ligand discrimination. Nat Commun 2019; 10:5728. [PMID: 31844059 PMCID: PMC6914780 DOI: 10.1038/s41467-019-13600-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 11/13/2019] [Indexed: 12/16/2022] Open
Abstract
Riboswitches are metabolite-sensing, conserved domains located in non-coding regions of mRNA that are central to regulation of gene expression. Here we report the first three-dimensional structure of the recently discovered S-adenosyl-L-methionine responsive SAM-VI riboswitch. SAM-VI adopts a unique fold and ligand pocket that are distinct from all other known SAM riboswitch classes. The ligand binds to the junctional region with its adenine tightly intercalated and Hoogsteen base-paired. Furthermore, we reveal the ligand discrimination mode of SAM-VI by additional X-ray structures of this riboswitch bound to S-adenosyl-L-homocysteine and a synthetic ligand mimic, in combination with isothermal titration calorimetry and fluorescence spectroscopy to explore binding thermodynamics and kinetics. The structure is further evaluated by analysis of ligand binding to SAM-VI mutants. It thus provides a thorough basis for developing synthetic SAM cofactors for applications in chemical and synthetic RNA biology.
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Affiliation(s)
- Aiai Sun
- Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China
| | - Catherina Gasser
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria
| | - Fudong Li
- National Science Center for Physical Sciences at Microscale Division of Molecular & Cell Biophysics and School of Life Sciences, University of Science and Technology of China, 230026, Hefei, China
| | - Hao Chen
- Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China
| | - Stefan Mair
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria
| | - Olga Krasheninina
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria
| | - Ronald Micura
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria.
| | - Aiming Ren
- Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
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31
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Zhang K, Li S, Kappel K, Pintilie G, Su Z, Mou TC, Schmid MF, Das R, Chiu W. Cryo-EM structure of a 40 kDa SAM-IV riboswitch RNA at 3.7 Å resolution. Nat Commun 2019; 10:5511. [PMID: 31796736 PMCID: PMC6890682 DOI: 10.1038/s41467-019-13494-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 11/03/2019] [Indexed: 01/17/2023] Open
Abstract
Specimens below 50 kDa have generally been considered too small to be analyzed by single-particle cryo-electron microscopy (cryo-EM). The high flexibility of pure RNAs makes it difficult to obtain high-resolution structures by cryo-EM. In bacteria, riboswitches regulate sulfur metabolism through binding to the S-adenosylmethionine (SAM) ligand and offer compelling targets for new antibiotics. SAM-I, SAM-I/IV, and SAM-IV are the three most commonly found SAM riboswitches, but the structure of SAM-IV is still unknown. Here, we report the structures of apo and SAM-bound SAM-IV riboswitches (119-nt, ~40 kDa) to 3.7 Å and 4.1 Å resolution, respectively, using cryo-EM. The structures illustrate homologies in the ligand-binding core but distinct peripheral tertiary contacts in SAM-IV compared to SAM-I and SAM-I/IV. Our results demonstrate the feasibility of resolving small RNAs with enough detail to enable detection of their ligand-binding pockets and suggest that cryo-EM could play a role in structure-assisted drug design for RNA.
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Affiliation(s)
- Kaiming Zhang
- Department of Bioengineering, and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Shanshan Li
- Department of Bioengineering, and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Kalli Kappel
- Biophysics Program, Stanford University, Stanford, CA, 94305, USA
| | - Grigore Pintilie
- Department of Bioengineering, and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Zhaoming Su
- Department of Bioengineering, and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Tung-Chung Mou
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
| | - Michael F Schmid
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, 94025, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA.
- Department of Physics, Stanford University, Stanford, CA, 94305, USA.
| | - Wah Chiu
- Department of Bioengineering, and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA.
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, 94025, USA.
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32
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Kanwal F, Chen T, Zhang Y, Simair A, Lu C. A Modified In Vitro Transcription Approach to Improve RNA Synthesis and Ribozyme Cleavage Efficiency. Mol Biotechnol 2019; 61:469-476. [PMID: 30868354 DOI: 10.1007/s12033-019-00167-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
RNA elements such as catalytic RNA, riboswitch, microRNA, and long non-coding RNA perform a major role in cellular processes. A complete understanding of cellular processes is impossible without knowing the structure-function relationship of participating RNA molecules that ultimately requires large quantities of pure RNAs. Thus, structural/functional analyses of emerging RNAs necessitate revised protocols for improved RNA quantity and quality. Here we present a modified in vitro transcription protocol to enhance ribozyme cleaving efficiency and RNA yield by working on two variables, i.e., incubation temperature and limiting GTPs. Following an improved RNA synthesis, the target RNA is purified from transcription mixture components through denaturing size-exclusion chromatography. The protocol confirms that cyclic elevated incubation temperatures during transcription and increased concentrations of GTPs improve the production rate of RNA. Our modified in vitro transcription method improves the ribozyme cleaving efficiency and targets RNA yield by four- to fivefold that can benefit almost any RNA-related study from protein-RNA interaction analysis to crystallography.
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Affiliation(s)
- Fariha Kanwal
- Key Laboratory of Science and Technology of Eco-Textiles, Ministry of Education, College of Chemistry, Chemical Engineering and Biotechnology, DongHua University, 2999 North Ren Min Road, Shanghai, 201620, China
| | - Ting Chen
- Key Laboratory of Science and Technology of Eco-Textiles, Ministry of Education, College of Chemistry, Chemical Engineering and Biotechnology, DongHua University, 2999 North Ren Min Road, Shanghai, 201620, China
| | - Yunlong Zhang
- Key Laboratory of Science and Technology of Eco-Textiles, Ministry of Education, College of Chemistry, Chemical Engineering and Biotechnology, DongHua University, 2999 North Ren Min Road, Shanghai, 201620, China
| | - Altaf Simair
- Key Laboratory of Science and Technology of Eco-Textiles, Ministry of Education, College of Chemistry, Chemical Engineering and Biotechnology, DongHua University, 2999 North Ren Min Road, Shanghai, 201620, China
| | - Changrui Lu
- Key Laboratory of Science and Technology of Eco-Textiles, Ministry of Education, College of Chemistry, Chemical Engineering and Biotechnology, DongHua University, 2999 North Ren Min Road, Shanghai, 201620, China.
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33
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Kim H, Jaffrey SR. A Fluorogenic RNA-Based Sensor Activated by Metabolite-Induced RNA Dimerization. Cell Chem Biol 2019; 26:1725-1731.e6. [PMID: 31631009 DOI: 10.1016/j.chembiol.2019.09.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 08/02/2019] [Accepted: 09/26/2019] [Indexed: 11/30/2022]
Abstract
Corn is a fluorogenic RNA aptamer that forms a high-affinity quasi-symmetric homodimer. The Corn dimer interface binds DFHO, resulting in highly photostable yellow fluorescence. Because of its photostability, Corn would be useful in RNA-based small-molecule biosensors, where quantitative accuracy would be affected by photobleaching. Here we describe a strategy for converting the constitutive Corn dimer into a small-molecule-regulated fluorescent biosensor that detects S-adenosylmethionine (SAM) in vitro and in living cells. We fused the Corn aptamer into a helical stem that was engineered by circularly permuting the SAM aptamer from the SAM-III riboswitch. In the absence of SAM, the Corn portion of this fusion RNA is unable to dimerize. However, upon binding SAM, the RNA dimerizes and binds DFHO. This RNA-based biosensor enables detection of SAM dynamics in living mammalian cells. Together, these data describe a class of RNA-based biosensor based on small-molecule-regulated dimerization of Corn.
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Affiliation(s)
- Hyaeyeong Kim
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY 10065, USA.
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34
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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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35
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Sung HL, Nesbitt DJ. Single-Molecule FRET Kinetics of the Mn 2+ Riboswitch: Evidence for Allosteric Mg 2+ Control of "Induced-Fit" vs "Conformational Selection" Folding Pathways. J Phys Chem B 2019; 123:2005-2015. [PMID: 30739441 DOI: 10.1021/acs.jpcb.8b11841] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gene expression in bacteria is often regulated dynamically by conformational changes in a riboswitch upon ligand binding, a detailed understanding of which is very much in its infancy. For example, the manganese riboswitch is a widespread RNA motif that conformationally responds in regulating bacterial gene expression to micromolar levels of its eponymous ligand, Mn2+, but the mechanistic pathways are poorly understood. In this work, we quantitatively explore the dynamic folding behavior of the manganese riboswitch by single-molecule fluorescence resonance energy transfer spectroscopy as a function of cation/ligand conditions. From the detailed analysis of the kinetics, the Mn2+ is shown to fold the riboswitch by a "bind-then-fold" (i.e., "induced-fit", IF) mechanism, whereby the ligand binds first and then promotes folding. On the other hand, the data also clearly reveal the presence of a folded yet ligand-free structure predominating due to the addition of physiological Mg2+ to a nonselective metal ion binding site. Of particular kinetic interest, such a Mg2+ "prefolded" conformation of the riboswitch is shown to exhibit a significantly increased affinity for Mn2+ and further stabilization by subsequent binding of the ligand, thereby promoting efficient riboswitch folding by a "fold-then-bind" (i.e., "conformational selection", CS) mechanism. Our results not only demonstrate Mg2+-controlled switching between IF and CS riboswitch folding pathways but also suggest a novel heterotropic allosteric control in the manganese riboswitch activity co-regulated by Mg2+ binding.
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36
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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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37
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Huang L, Lilley DMJ. Structure and ligand binding of the SAM-V riboswitch. Nucleic Acids Res 2018; 46:6869-6879. [PMID: 29931337 PMCID: PMC6061858 DOI: 10.1093/nar/gky520] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/22/2018] [Accepted: 05/25/2018] [Indexed: 11/29/2022] Open
Abstract
SAM-V is one of the class of riboswitches that bind S-adenosylmethione, regulating gene expression by controlling translation. We have solved the crystal structure of the metY SAM-V riboswitch bound to its SAM ligand at 2.5 Å resolution. The RNA folds as an H-type pseudoknot, with a major-groove triple helix in which resides the SAM ligand binding site. The bound SAM adopts an elongated conformation aligned with the axis of the triple helix, and is held at either end by hydrogen bonding to the adenine and the amino acid moieties. The central sulfonium cation makes electrostatic interactions with an U:A.U base triple, so conferring specificity. We propose a model in which SAM binding leads to association of the triplex third strand that stabilizes a short helix and occludes the ribosome binding site. Thus the new structure explains both ligand specificity and the mechanism of genetic control.
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Affiliation(s)
- Lin Huang
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
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38
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Šponer J, Bussi G, Krepl M, Banáš P, Bottaro S, Cunha RA, Gil-Ley A, Pinamonti G, Poblete S, Jurečka P, Walter NG, Otyepka M. RNA Structural Dynamics As Captured by Molecular Simulations: A Comprehensive Overview. Chem Rev 2018; 118:4177-4338. [PMID: 29297679 PMCID: PMC5920944 DOI: 10.1021/acs.chemrev.7b00427] [Citation(s) in RCA: 336] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Indexed: 12/14/2022]
Abstract
With both catalytic and genetic functions, ribonucleic acid (RNA) is perhaps the most pluripotent chemical species in molecular biology, and its functions are intimately linked to its structure and dynamics. Computer simulations, and in particular atomistic molecular dynamics (MD), allow structural dynamics of biomolecular systems to be investigated with unprecedented temporal and spatial resolution. We here provide a comprehensive overview of the fast-developing field of MD simulations of RNA molecules. We begin with an in-depth, evaluatory coverage of the most fundamental methodological challenges that set the basis for the future development of the field, in particular, the current developments and inherent physical limitations of the atomistic force fields and the recent advances in a broad spectrum of enhanced sampling methods. We also survey the closely related field of coarse-grained modeling of RNA systems. After dealing with the methodological aspects, we provide an exhaustive overview of the available RNA simulation literature, ranging from studies of the smallest RNA oligonucleotides to investigations of the entire ribosome. Our review encompasses tetranucleotides, tetraloops, a number of small RNA motifs, A-helix RNA, kissing-loop complexes, the TAR RNA element, the decoding center and other important regions of the ribosome, as well as assorted others systems. Extended sections are devoted to RNA-ion interactions, ribozymes, riboswitches, and protein/RNA complexes. Our overview is written for as broad of an audience as possible, aiming to provide a much-needed interdisciplinary bridge between computation and experiment, together with a perspective on the future of the field.
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Affiliation(s)
- Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences , Kralovopolska 135 , Brno 612 65 , Czech Republic
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences , Kralovopolska 135 , Brno 612 65 , Czech Republic
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| | - Pavel Banáš
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| | - Sandro Bottaro
- Structural Biology and NMR Laboratory, Department of Biology , University of Copenhagen , Copenhagen 2200 , Denmark
| | - Richard A Cunha
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Alejandro Gil-Ley
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Giovanni Pinamonti
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Simón Poblete
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Petr Jurečka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| | - Nils G Walter
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
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New tRNA contacts facilitate ligand binding in a Mycobacterium smegmatis T box riboswitch. Proc Natl Acad Sci U S A 2018; 115:3894-3899. [PMID: 29581302 DOI: 10.1073/pnas.1721254115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
T box riboswitches are RNA regulatory elements widely used by organisms in the phyla Firmicutes and Actinobacteria to regulate expression of amino acid-related genes. Expression of T box family genes is down-regulated by transcription attenuation or inhibition of translation initiation in response to increased charging of the cognate tRNA. Three direct contacts with tRNA have been described; however, one of these contacts is absent in a subclass of T box RNAs and the roles of several structural domains conserved in most T box RNAs are unknown. In this study, structural elements of a Mycobacterium smegmatis ileS T box riboswitch variant with an Ultrashort (US) Stem I were sequentially deleted, which resulted in a progressive decrease in binding affinity for the tRNAIle ligand. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) revealed structural changes in conserved riboswitch domains upon interaction with the tRNA ligand. Cross-linking and mutational analyses identified two interaction sites, one between the S-turn element in Stem II and the T arm of tRNAIle and the other between the Stem IIA/B pseudoknot and the D loop of tRNAIle These newly identified RNA contacts add information about tRNA recognition by the T box riboswitch and demonstrate a role for the S-turn and pseudoknot elements, which resemble structural elements that are common in many cellular RNAs.
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40
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Designing fluorescent biosensors using circular permutations of riboswitches. Methods 2018; 143:102-109. [PMID: 29458090 DOI: 10.1016/j.ymeth.2018.02.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/31/2018] [Accepted: 02/14/2018] [Indexed: 02/06/2023] Open
Abstract
RNA-based fluorescent (RBF) biosensors have been applied to detect a variety of metabolites in vitro and in live cells. They are designed by combining the ligand sensing domain of natural riboswitches with in vitro selected fluorogenic aptamers. Different biosensor topologies have been developed to accommodate the diversity of riboswitch structures. Here we show that circular permutation of the riboswitch ligand sensing domain also gives functional biosensors, using the SAM-I riboswitch as our model. We reveal that this design can enhance fluorescence turn-on and ligand binding affinity compared to the non-permuted topology.
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Mirihana Arachchilage G, Sherlock ME, Weinberg Z, Breaker RR. SAM-VI RNAs selectively bind S-adenosylmethionine and exhibit similarities to SAM-III riboswitches. RNA Biol 2018; 15:371-378. [PMID: 29106323 DOI: 10.1080/15476286.2017.1399232] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Five distinct riboswitch classes that regulate gene expression in response to the cofactor S-adenosylmethionine (SAM) or its metabolic breakdown product S-adenosylhomocysteine (SAH) have been reported previously. Collectively, these SAM- or SAH-sensing RNAs constitute the most abundant collection of riboswitches, and are found in nearly every major bacterial lineage. Here, we report a potential sixth member of this pervasive riboswitch family, called SAM-VI, which is predominantly found in Bifidobacterium species. SAM-VI aptamers selectively bind the cofactor SAM and strongly discriminate against SAH. The consensus sequence and structural model for SAM-VI share some features with the consensus model for the SAM-III riboswitch class, whose members are mainly found in lactic acid bacteria. However, there are sufficient differences between the two classes such that current bioinformatics methods separately cluster representatives of the two motifs. These findings highlight the abundance of RNA structures that can form to selectively recognize SAM, and showcase the ability of RNA to utilize diverse strategies to perform similar biological functions.
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Affiliation(s)
| | - Madeline E Sherlock
- b Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , CT , USA
| | - Zasha Weinberg
- a Howard Hughes Medical Institute, Yale University , New Haven , CT , USA
| | - Ronald R Breaker
- a Howard Hughes Medical Institute, Yale University , New Haven , CT , USA.,b Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , CT , USA.,c Department of Molecular , Cellular and Developmental Biology, Yale University , New Haven , CT , USA
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42
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Development of a genetically encodable FRET system using fluorescent RNA aptamers. Nat Commun 2018; 9:18. [PMID: 29295996 PMCID: PMC5750238 DOI: 10.1038/s41467-017-02435-x] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/30/2017] [Indexed: 12/21/2022] Open
Abstract
Fluorescent RNA aptamers are useful as markers for tracking RNA molecules inside cells and for creating biosensor devices. Förster resonance energy transfer (FRET) based on fluorescent proteins has been used to detect conformational changes, however, such FRET devices have not yet been produced using fluorescent RNA aptamers. Here we develop an RNA aptamer-based FRET (apta-FRET) system using single-stranded RNA origami scaffolds. To obtain FRET, the fluorescent aptamers Spinach and Mango are placed in close proximity on the RNA scaffolds and a new fluorophore is synthesized to increase spectral overlap. RNA devices that respond to conformational changes are developed, and finally, apta-FRET constructs are expressed in E. coli where FRET is observed, demonstrating that the apta-FRET system is genetically encodable and that the RNA nanostructures fold correctly in bacteria. We anticipate that the RNA apta-FRET system could have applications as ratiometric sensors for real-time studies in cell and synthetic biology. FRET has been used to study protein conformational changes but has never been applied to RNA aptamers. Here the authors develop a genetically encodable RNA aptamer-based FRET system on single-stranded RNA origami scaffolds, and demonstrate it can be used to study RNA conformational changes.
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43
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Studying Parasite Gene Function and Interaction Through Ribozymes and Riboswitches Design Mechanism. Synth Biol (Oxf) 2018. [DOI: 10.1007/978-981-10-8693-9_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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RNA-Based Fluorescent Biosensors for Detecting Metabolites in vitro and in Living Cells. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 82:187-203. [PMID: 29413520 DOI: 10.1016/bs.apha.2017.09.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Genetically encoded sensors are important tools for measuring metabolites and other small molecules in vitro and in live cells. Until recently, genetically encoded sensors exclusively comprised fluorescent proteins that undergo changes in Förster resonance energy transfer upon binding a target analyte. However, recently a new class of fluorescent sensor has been developed composed of RNA. These RNA-based sensors rely on Spinach and other RNA mimics of green fluorescent protein. In each case, the RNA-based sensors contain an analyte-binding aptamer domain which transduces binding of the analyte into a conformational change in Spinach. Two types of sensors have been developed: allosteric Spinach sensors and Spinach riboswitches. Allosteric Spinach sensors exhibit metabolite-induced folding and subsequent fluorescence. Spinach riboswitches are naturally occurring riboswitches that have been modified to contain the Spinach aptamer. The resulting RNA is a fluorogenic riboswitch, and produces fluorescence upon binding its cognate analyte. We describe the development of this new technology, its uses, and future directions to facilitate the use of this assay technology in mammalian cells and in high-throughput applications.
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Abstract
Riboswitches are cis-acting gene regulatory elements and constitute potential targets for new antibiotics. Recent studies in this field have started to explore these targets for drug discovery. New ligands found by fragment screening, design of analogs of the natural ligands or serendipitously by phenotypic screening have shown antibacterial effects in cell assays against a range of bacteria strains and in animal models. In this review, we highlight the most advanced drug design work of riboswitch ligands and discuss the challenges in the field with respect to the development of antibiotics with a new mechanism of action.
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46
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Kanazawa H, Kondo J. Crystal structure of a novel RNA motif that allows for precise positioning of a single metal ion. J Inorg Biochem 2017; 176:140-143. [PMID: 28898762 DOI: 10.1016/j.jinorgbio.2017.08.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/15/2017] [Accepted: 08/30/2017] [Indexed: 11/18/2022]
Abstract
We have determined a crystal structure of an RNA duplex containing a novel metal-binding motif. The motif is composed of two sheared G○A base pairs, two unpaired A residues and four phosphate groups in close proximity. Four A residues make an A-A-A-A stacking column at the minor groove side and two G bases are highly inclined, thereby forming the pocket-shaped motif at the major groove side. In the present structure, a hydrated Sr2+ ion exists in the pocket and binds to the O6 and N7 atoms of the two G bases and four phosphate groups. According to the previously-reported metal-binding properties to RNA molecules, many of divalent cations, such as Mg2+, Mn2+, Co2+, Zn2+, Ba2+, Pb2+ and Cd2+, may bind to the motif. This metal-binding motif can be used as a modular building block that allows for precise positioning of a single metal ion in functional nucleic acid molecules.
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Affiliation(s)
- Hiroki Kanazawa
- Graduate School of Science and Technology, Sophia University, Tokyo 102-8554, Japan
| | - Jiro Kondo
- Graduate School of Science and Technology, Sophia University, Tokyo 102-8554, Japan; Department of Materials and Life Sciences, Sophia University, Tokyo 102-8554, Japan.
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47
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Sherwood AV, Henkin TM. Riboswitch-Mediated Gene Regulation: Novel RNA Architectures Dictate Gene Expression Responses. Annu Rev Microbiol 2017; 70:361-74. [PMID: 27607554 DOI: 10.1146/annurev-micro-091014-104306] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Riboswitches are RNA elements that act on the mRNA with which they are cotranscribed to modulate expression of that mRNA. These elements are widely found in bacteria, where they have a broad impact on gene expression. The defining feature of riboswitches is that they directly recognize a physiological signal, and the resulting shift in RNA structure affects gene regulation. The majority of riboswitches respond to cellular metabolites, often in a feedback loop to repress synthesis of the enzymes used to produce the metabolite. Related elements respond to the aminoacylation status of a specific tRNA or to a physical parameter, such as temperature or pH. Recent studies have identified new classes of riboswitches and have revealed new insights into the molecular mechanisms of signal recognition and gene regulation. Application of structural and biophysical approaches has complemented previous genetic and biochemical studies, yielding new information about how different riboswitches operate.
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Affiliation(s)
- Anna V Sherwood
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210; .,Molecular, Cellular and Developmental Graduate Program, The Ohio State University, Columbus, Ohio 43210
| | - Tina M Henkin
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210;
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Abstract
In addition to continuous rapid progress in RNA structure determination, probing, and biophysical studies, the past decade has seen remarkable advances in the development of a new generation of RNA folding theories and models. In this article, we review RNA structure prediction models and models for ion-RNA and ligand-RNA interactions. These new models are becoming increasingly important for a mechanistic understanding of RNA function and quantitative design of RNA nanotechnology. We focus on new methods for physics-based, knowledge-based, and experimental data-directed modeling for RNA structures and explore the new theories for the predictions of metal ion and ligand binding sites and metal ion-dependent RNA stabilities. The integration of these new methods with theories about the cellular environment effects in RNA folding, such as molecular crowding and cotranscriptional kinetic effects, may ultimately lead to an all-encompassing RNA folding model.
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Affiliation(s)
- Li-Zhen Sun
- Department of Physics, Department of Biochemistry, and MU Informatics Institute, University of Missouri, Columbia, Missouri 65211;
| | - Dong Zhang
- Department of Physics, Department of Biochemistry, and MU Informatics Institute, University of Missouri, Columbia, Missouri 65211;
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry, and MU Informatics Institute, University of Missouri, Columbia, Missouri 65211;
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49
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Battaglia RA, Price IR, Ke A. Structural basis for guanidine sensing by the ykkC family of riboswitches. RNA (NEW YORK, N.Y.) 2017; 23:578-585. [PMID: 28096518 PMCID: PMC5340920 DOI: 10.1261/rna.060186.116] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/09/2017] [Indexed: 05/20/2023]
Abstract
Regulation of gene expression by cis-encoded riboswitches is a prevalent theme in bacteria. Of the hundreds of riboswitch families identified, the majority of them remain as orphans, without a clear ligand assignment. The ykkC orphan family was recently characterized as guanidine-sensing riboswitches. Herein we present a 2.3 Å crystal structure of the guanidine-bound ykkC riboswitch from Dickeya dadantii The riboswitch folds into a boot-shaped structure, with a coaxially stacked P1/P2 stem forming the boot, and a 3'-P3 stem-loop forming the heel. Sophisticated base-pairing and cross-helix tertiary contacts give rise to the ligand-binding pocket between the boot and the heel. The guanidine is recognized in its positively charged guanidinium form, in its sp2 hybridization state, through a network of coplanar hydrogen bonds and by a cation-π stacking contact on top of a conserved guanosine residue. Disruption of these contacts resulted in severe guanidinium-binding defects. These results provide the structural basis for specific guanidine sensing by ykkC riboswitches and pave the way for a deeper understanding of guanidine detoxification-a previously unappreciated aspect of bacterial physiology.
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Affiliation(s)
- Robert A Battaglia
- Department of Molecular Biology and Genetics, Ithaca, New York 14853, USA
| | - Ian R Price
- Department of Molecular Biology and Genetics, Ithaca, New York 14853, USA
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Ithaca, New York 14853, USA
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50
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Jones CP, Ferré-D'Amaré AR. Long-Range Interactions in Riboswitch Control of Gene Expression. Annu Rev Biophys 2017; 46:455-481. [PMID: 28375729 DOI: 10.1146/annurev-biophys-070816-034042] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Riboswitches are widespread RNA motifs that regulate gene expression in response to fluctuating metabolite concentrations. Known primarily from bacteria, riboswitches couple specific ligand binding and changes in RNA structure to mRNA expression in cis. Crystal structures of the ligand binding domains of most of the phylogenetically widespread classes of riboswitches, each specific to a particular metabolite or ion, are now available. Thus, the bound states-one end point-have been thoroughly characterized, but the unbound states have been more elusive. Consequently, it is less clear how the unbound, sensing riboswitch refolds into the ligand binding-induced output state. The ligand recognition mechanisms of riboswitches are diverse, but we find that they share a common structural strategy in positioning their binding sites at the point of the RNA three-dimensional fold where the residues farthest from one another in sequence meet. We review how riboswitch folds adhere to this fundamental strategy and propose future research directions for understanding and harnessing their ability to specifically control gene expression.
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Affiliation(s)
- Christopher P Jones
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
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