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Koob T, Döpp S, Schwalbe H. 1H, 13C, 15N and 31P chemical shift assignment of the first stem-loop Guanidine-II riboswitch from Escherichia coli. BIOMOLECULAR NMR ASSIGNMENTS 2025; 19:53-58. [PMID: 39890743 DOI: 10.1007/s12104-025-10217-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2024] [Accepted: 01/09/2025] [Indexed: 02/03/2025]
Abstract
A comprehensive understanding of RNA-based gene regulation is a fundamental aspect for the development of innovative therapeutic options in medicine and for a more targeted response to environmental problems. Within the different mechanisms of RNA-based gene regulation, riboswitches are particularly interesting as they change their structure in response to the interaction with a low molecular weight ligand, often a well-known metabolite. Four distinct classes of riboswitches recognize the very small guanidinium cation. We are focused on the Guanidine-II riboswitch with the mini-ykkC motif. We report here the assignment of the 1H, 13C, 15N and 31P chemical shifts of the 23 nucleotide-long sequence of the first stem-loop of the Guanidine-II riboswitch aptamer from Escherichia coli. Despite its small size, the assignment of the NMR signals of this RNA proved to be challenging as it has symmetrical base pairs and palindromic character.
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Affiliation(s)
- Tatjana Koob
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Max‑von‑Laue‑Str. 7, 60438, Frankfurt/M, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max‑von‑Laue‑Str. 9, 60438, Frankfurt/M, Germany
| | - Silas Döpp
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Max‑von‑Laue‑Str. 7, 60438, Frankfurt/M, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max‑von‑Laue‑Str. 9, 60438, Frankfurt/M, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Max‑von‑Laue‑Str. 7, 60438, Frankfurt/M, Germany.
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max‑von‑Laue‑Str. 9, 60438, Frankfurt/M, Germany.
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2
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Franke L, Globisch C, Karakurt MC, Stephan T, Peter C. Atomistic Simulations Reveal Crucial Role of Metal Ions for Ligand Binding in Guanidine-I Riboswitch. Macromol Rapid Commun 2024; 45:e2400606. [PMID: 39225633 PMCID: PMC11661666 DOI: 10.1002/marc.202400606] [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: 07/25/2024] [Revised: 08/22/2024] [Indexed: 09/04/2024]
Abstract
Riboswitches are structured ribonucleic acid (RNA) segments that act as specific sensors for small molecules in bacterial metabolism. Due to the flexible nature of these highly charged macromolecules, molecular dynamics simulations are instrumental to investigating the mechanistic details of their regulatory function. In the present study, the guanidine-I riboswitch serves as an example of how atomistic simulations can shed light on the effect of ions on the structure and dynamics of RNA and on ligand binding. Relying on two orthologous crystal structures from different bacterial species, it is demonstrated how the ion setup crucially determines whether the simulation yields meaningful insights into the conformational stability of the RNA, functionally relevant residues and RNA-ligand interactions. The ion setup in this context includes diffuse ions in solution and bound ions associated directly with the RNA, in particular a triad of 2 Mg2+ ions and a K+ ion in close proximity to the guanidinium binding site. A detailed investigation of the binding pocket reveals that the K+ from the ion triad plays a decisive role in stabilizing the ligand binding by stabilizing important localized interactions, which in turn contribute to the overall shape of the folded state of the RNA.
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Affiliation(s)
- Leon Franke
- Department of ChemistryUniversity of KonstanzUniversitätsstraße 1078457KonstanzGermany
| | - Christoph Globisch
- Department of ChemistryUniversity of KonstanzUniversitätsstraße 1078457KonstanzGermany
| | - Mehmet Can Karakurt
- Department of ChemistryUniversity of KonstanzUniversitätsstraße 1078457KonstanzGermany
| | - Theresa Stephan
- Department of ChemistryUniversity of KonstanzUniversitätsstraße 1078457KonstanzGermany
| | - Christine Peter
- Department of ChemistryUniversity of KonstanzUniversitätsstraße 1078457KonstanzGermany
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3
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Feng S, Xiao W, Yu Y, Liu G, Zhang Y, Chen T, Lu C. Linker-Mediated Inactivation of the SAM-II Domain in the Tandem SAM-II/SAM-V Riboswitch. Int J Mol Sci 2024; 25:11288. [PMID: 39457069 PMCID: PMC11508383 DOI: 10.3390/ijms252011288] [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: 09/25/2024] [Revised: 10/16/2024] [Accepted: 10/18/2024] [Indexed: 10/28/2024] Open
Abstract
Tandem SAM-II/SAM-V riboswitch belongs to a class of riboswitches found in the marine bacterium 'Candidatus Pelagibacter ubique'. Previous studies have demonstrated that these riboswitches have the potential for digital modulation of gene expression at both the transcriptional and translational levels. In this study, we investigate the conformational changes in the tandem SAM-II/SAM-V riboswitch binding to S-adenosylmethionine (SAM) using selective 2'-hydroxyl acylation analyzed by the primer extension (SHAPE) assay, small-angle X-ray scattering (SAXS), and oligos depressing probing. Our findings reveal that the linker between SAM-II/SAM-V aptamers blocks the SAM response of the SAM-II domain. This result proposes a new mechanism for gene expression regulation, where the ligand-binding functions of tandem riboswitches can be selectively masked or released through a linker.
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Affiliation(s)
- Shanshan Feng
- College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China; (S.F.); (W.X.); (Y.Y.); (Y.Z.); (T.C.)
| | - Wenwen Xiao
- College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China; (S.F.); (W.X.); (Y.Y.); (Y.Z.); (T.C.)
| | - Yingying Yu
- College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China; (S.F.); (W.X.); (Y.Y.); (Y.Z.); (T.C.)
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China;
| | - Yunlong Zhang
- College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China; (S.F.); (W.X.); (Y.Y.); (Y.Z.); (T.C.)
| | - Ting Chen
- College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China; (S.F.); (W.X.); (Y.Y.); (Y.Z.); (T.C.)
| | - Changrui Lu
- College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China; (S.F.); (W.X.); (Y.Y.); (Y.Z.); (T.C.)
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4
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Steuer J, Sinn M, Eble F, Rütschlin S, Böttcher T, Hartig JS, Peter C. Cooperative binding of bivalent ligands yields new insights into the guanidine-II riboswitch. NAR Genom Bioinform 2024; 6:lqae132. [PMID: 39323654 PMCID: PMC11423145 DOI: 10.1093/nargab/lqae132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 08/23/2024] [Accepted: 09/12/2024] [Indexed: 09/27/2024] Open
Abstract
Riboswitches are involved in regulating the gene expression in bacteria. They are located within the untranslated regions of bacterial messenger RNA and function as switches by adjusting their shape, depending on the presence or absence of specific ligands. To decipher the fundamental aspects of bacterial gene control, it is therefore important to understand the mechanisms that underlie these conformational switches. To this end, a combination of an experimental binding study, molecular simulations and machine learning has been employed to obtain insights into the conformational changes and structural dynamics of the guanidine-II riboswitch. By exploiting the design of a bivalent ligand, we were able to study ligand binding in the aptamer dimer at the molecular level. Spontaneous ligand-binding events, which are usually difficult to simulate, were observed and the contributing factors are described. These findings were further confirmed by in vivo experiments, where the cooperative binding effects of the bivalent ligands resulted in increased binding affinity compared to the native guanidinium ligand. Beyond ligand binding itself, the simulations revealed a novel, ligand-dependent base-stacking interaction outside of the binding pocket that stabilizes the riboswitch.
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Affiliation(s)
- Jakob Steuer
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
| | - Malte Sinn
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Franziska Eble
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Sina Rütschlin
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
| | - Thomas Böttcher
- Faculty of Chemistry, Institute for Biological Chemistry & Centre for Microbiology and Environmental Systems Science, Department of Microbiology and Ecosystems Science, University of Vienna, Josef-Holaubek-Platz 2 (UZA II), 1090 Vienna, Austria
| | - Jörg S Hartig
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
| | - Christine Peter
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
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5
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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: 8] [Impact Index Per Article: 8.0] [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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6
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Singh K, Reddy G. Excited States of apo-Guanidine-III Riboswitch Contribute to Guanidinium Binding through Both Conformational and Induced-Fit Mechanisms. J Chem Theory Comput 2024; 20:421-435. [PMID: 38134376 DOI: 10.1021/acs.jctc.3c00999] [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: 12/24/2023]
Abstract
Riboswitches are mRNA segments that regulate gene expression through conformational changes driven by their cognate ligand binding. The ykkC motif forms a riboswitch class that selectively senses a guanidinium ion (Gdm+) and regulates the downstream expression of proteins which aid in the efflux of excess Gdm+ from the cells. The aptamer domain (AD) of the guanidine-III riboswitch forms an H-type pseudoknot with a triple helical domain that binds a Gdm+. We studied the binding of Gdm+ to the AD of the guanidine (ykkC)-III riboswitch using computer simulations to probe the specificity of the riboswitch to Gdm+ binding. We show that Gdm+ binding is a fast process occurring on the nanosecond time scale, with minimal conformational changes to the AD. Using machine learning and Markov-state models, we identified the excited conformational states of the AD, which have a high Gdm+ binding propensity, making the Gdm+ binding landscape complex exhibiting both conformational selection and induced-fit mechanisms. The proposed apo-AD excited states and their role in the ligand-sensing mechanism are amenable to experimental verification. Further, targeting these excited-state conformations in discovering new antibiotics can be explored.
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Affiliation(s)
- Kushal Singh
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012 Karnataka, India
| | - Govardhan Reddy
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012 Karnataka, India
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7
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Bu F, Lin X, Liao W, Lu Z, He Y, Luo Y, Peng X, Li M, Huang Y, Chen X, Xiao B, Jiang J, Deng J, Huang J, Lin T, Miao Z, Huang L. Ribocentre-switch: a database of riboswitches. Nucleic Acids Res 2024; 52:D265-D272. [PMID: 37855663 PMCID: PMC10767811 DOI: 10.1093/nar/gkad891] [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: 08/03/2023] [Revised: 09/19/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023] Open
Abstract
Riboswitches are regulatory elements found in the untranslated regions (UTRs) of certain mRNA molecules. They typically comprise two distinct domains: an aptamer domain that can bind to specific small molecules, and an expression platform that controls gene expression. Riboswitches work by undergoing a conformational change upon binding to their specific ligand, thus activating or repressing the genes downstream. This mechanism allows gene expression regulation in response to metabolites or small molecules. To systematically summarise riboswitch structures and their related ligand binding functions, we present Ribocentre-switch, a comprehensive database of riboswitches, including the information as follows: sequences, structures, functions, ligand binding pockets and biological applications. It encompasses 56 riboswitches and 26 orphan riboswitches from over 430 references, with a total of 89 591 sequences. It serves as a good resource for comparing different riboswitches and facilitating the identification of potential riboswitch candidates. Therefore, it may facilitate the understanding of RNA structural conformational changes in response to ligand signaling. The database is publicly available at https://riboswitch.ribocentre.org.
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Affiliation(s)
- Fan Bu
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases,Guangzhou National Laboratory, Medical University, Guangzhou 510180, China
| | - Xiaowei Lin
- Department of Urology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
- 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
| | - Wenjian Liao
- Department of Urology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
- 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
| | - Zhizhong Lu
- School of Life Sciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yuanlin He
- 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
| | - Yuhang Luo
- 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
| | - Xuemei Peng
- 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
| | - Mengxiao Li
- 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
| | - Yuanyin 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
| | - Xiaoxue Chen
- 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
| | - Bowen Xiao
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases,Guangzhou National Laboratory, Medical University, Guangzhou 510180, China
| | - Jiuhong Jiang
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases,Guangzhou National Laboratory, Medical University, Guangzhou 510180, China
| | - Jie Deng
- 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
| | - Jian Huang
- Department of Urology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
- 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
| | - Tianxin Lin
- Department of Urology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
- 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
| | - Zhichao Miao
- Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Clinical Research Center for Anesthesiology and Perioperative Medicine, Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases,Guangzhou National Laboratory, Medical University, Guangzhou 510180, China
| | - 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
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8
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Hu G, Zhang Y, Yu Z, Cui T, Cui W. Dynamical characterization and multiple unbinding paths of two PreQ 1 ligands in one pocket. Phys Chem Chem Phys 2023; 25:24004-24015. [PMID: 37646322 DOI: 10.1039/d3cp03142j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Riboswitches naturally regulate gene expression in bacteria by binding to specific small molecules. Class 1 preQ1 riboswitch aptamer is an important model not only for RNA folding but also as a target for designing small molecule antibiotics due to its well-known minimal aptamer domain. Here, we ran a total of 62.4 μs conventional and enhanced-sampling molecular dynamics (MD) simulations to characterize the determinants underlying the binding of the preQ1-II riboswitch aptamer to two preQ1 ligands in one binding pocket. Decomposition of binding free energy suggested that preQ1 ligands at α and β sites interact with four nucleotides (G5, C17, C18, and A30) and two nucleotides (A12 and C31), respectively. Mg2+ ions play a crucial role in both stabilizing the binding pocket and facilitating ligand binding. The flexible preQ1 ligand at the β site leads to the top of the binding pocket loosening and thus pre-organizes the riboswitch for ligand entry. Enhanced sampling simulations further revealed that the preQ1 ligand at the α site unbinds through two orthogonal pathways, which are dependent on whether or not a β site preQ1 ligand is present. One of the two preQ1 ligands has been identified in the binding pocket, which will aid to identify the second preQ1 Ligand. Our work provides new information for designing robust ligands.
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Affiliation(s)
- Guodong Hu
- Shandong Key Laboratory of Biophysics, Dezhou University, Dezhou 253023, China.
- Laoling People's Hospital, Dezhou 253600, China
| | | | - Zhiping Yu
- Shandong Key Laboratory of Biophysics, Dezhou University, Dezhou 253023, China.
| | - Tiejun Cui
- Laoling People's Hospital, Dezhou 253600, China
| | - Wanling Cui
- Shandong Key Laboratory of Biophysics, Dezhou University, Dezhou 253023, China.
- Laoling People's Hospital, Dezhou 253600, China
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9
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Deng J, Fang X, Huang L, Li S, Xu L, Ye K, Zhang J, Zhang K, Zhang QC. RNA structure determination: From 2D to 3D. FUNDAMENTAL RESEARCH 2023; 3:727-737. [PMID: 38933295 PMCID: PMC11197651 DOI: 10.1016/j.fmre.2023.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 06/04/2023] [Accepted: 06/05/2023] [Indexed: 06/28/2024] Open
Abstract
RNA molecules serve a wide range of functions that are closely linked to their structures. The basic structural units of RNA consist of single- and double-stranded regions. In order to carry out advanced functions such as catalysis and ligand binding, certain types of RNAs can adopt higher-order structures. The analysis of RNA structures has progressed alongside advancements in structural biology techniques, but it comes with its own set of challenges and corresponding solutions. In this review, we will discuss recent advances in RNA structure analysis techniques, including structural probing methods, X-ray crystallography, nuclear magnetic resonance, cryo-electron microscopy, and small-angle X-ray scattering. Often, a combination of multiple techniques is employed for the integrated analysis of RNA structures. We also survey important RNA structures that have been recently determined using various techniques.
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Affiliation(s)
- Jie Deng
- 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
| | - Xianyang Fang
- Beijing Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - 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
| | - Shanshan Li
- MOE Key Laboratory for Cellular Dynamics and Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Lilei Xu
- Beijing Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinsong Zhang
- MOE Key Laboratory of Bioinformatics, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
| | - Kaiming Zhang
- MOE Key Laboratory for Cellular Dynamics and Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Qiangfeng Cliff Zhang
- MOE Key Laboratory of Bioinformatics, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
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10
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Focht CM, Hiller DA, Grunseich SG, Strobel SA. Translation regulation by a guanidine-II riboswitch is highly tunable in sensitivity, dynamic range, and apparent cooperativity. RNA (NEW YORK, N.Y.) 2023; 29:1126-1139. [PMID: 37130702 PMCID: PMC10351892 DOI: 10.1261/rna.079560.122] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 04/05/2023] [Indexed: 05/04/2023]
Abstract
Riboswitches function as important translational regulators in bacteria. Comprehensive mutational analysis of transcriptional riboswitches has been used to probe the energetic intricacies of interplay between the aptamer and expression platform, but translational riboswitches have been inaccessible to massively parallel techniques. The guanidine-II (gdm-II) riboswitch is an exclusively translational class. We have integrated RelE cleavage with next-generation sequencing to quantify ligand-dependent changes in translation initiation for all single and double mutations of the Pseudomonas aeruginosa gdm-II riboswitch, a total of more than 23,000 variants. This extensive mutational analysis is consistent with the prominent features of the bioinformatic consensus. These data indicate, unexpectedly, that direct sequestration of the Shine-Dalgarno sequence is dispensable for riboswitch function. Additionally, this comprehensive data set reveals important positions not identified in previous computational and crystallographic studies. Mutations in the variable linker region stabilize alternate conformations. The double mutant data reveal the functional importance of the previously modeled P0b helix formed by the 5' and 3' tails that serves as the basis for translational control. Additional mutations to GU wobble base pairs in both P1 and P2 reveal how the apparent cooperativity of the system involves an intricate network of communication between the two binding sites. This comprehensive examination of a translational riboswitch's expression platform illuminates how the riboswitch is precisely tuned and tunable with regard to ligand sensitivity, the amplitude of expression between ON and OFF states, and the cooperativity of ligand binding.
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Affiliation(s)
- Caroline M Focht
- Institute of Biochemical Design and Discovery, Yale University, West Haven, Connecticut 06516, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, USA
| | - David A Hiller
- Institute of Biochemical Design and Discovery, Yale University, West Haven, Connecticut 06516, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, USA
| | - Sabrina G Grunseich
- Institute of Biochemical Design and Discovery, Yale University, West Haven, Connecticut 06516, USA
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA
| | - Scott A Strobel
- Institute of Biochemical Design and Discovery, Yale University, West Haven, Connecticut 06516, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, USA
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA
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11
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Egli M, Zhang S. Ned Seeman and the prediction of amino acid-basepair motifs mediating protein-nucleic acid recognition. Biophys J 2022; 121:4777-4787. [PMID: 35711143 PMCID: PMC9808504 DOI: 10.1016/j.bpj.2022.06.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/04/2022] [Accepted: 06/10/2022] [Indexed: 01/07/2023] Open
Abstract
Fifty years ago, the first atomic-resolution structure of a nucleic acid double helix, the mini-duplex (ApU)2, revealed details of basepair geometry, stacking, sugar conformation, and backbone torsion angles, thereby superseding earlier models based on x-ray fiber diffraction, including the original DNA double helix proposed by Watson and Crick. Just 3 years later, in 1976, Ned Seeman, John Rosenberg, and Alex Rich leapt from their structures of mini-duplexes and H-bonding motifs between bases in small-molecule structures and transfer RNA to predicting how proteins could sequence specifically recognize double helix nucleic acids. They proposed interactions between amino acid side chains and nucleobases mediated by two hydrogen bonds in the major or minor grooves. One of these, the arginine-guanine pair, emerged as the most favored amino acid-base interaction in experimental structures of protein-nucleic acid complexes determined since 1986. In this brief review we revisit the pioneering work by Seeman et al. and discuss the importance of the arginine-guanine pairing motif.
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Affiliation(s)
- Martin Egli
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, Tennessee.
| | - Shuguang Zhang
- Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
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12
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Liu Y, Munsayac A, Hall I, Keane SC. Solution Structure of NPSL2, A Regulatory Element in the oncomiR-1 RNA. J Mol Biol 2022; 434:167688. [PMID: 35717998 PMCID: PMC9474619 DOI: 10.1016/j.jmb.2022.167688] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 12/22/2022]
Abstract
The miR-17 ∼ 92a polycistron, also known as oncomiR-1, is commonly overexpressed in multiple cancers and has several oncogenic properties. OncomiR-1 encodes six constituent microRNAs (miRs), each enzymatically processed with different efficiencies. However, the structural mechanism that regulates this differential processing remains unclear. Chemical probing of oncomiR-1 revealed that the Drosha cleavage sites of pri-miR-92a are sequestered in a four-way junction. NPSL2, an independent stem loop element, is positioned just upstream of pri-miR-92a and sequesters a crucial part of the sequence that constitutes the basal helix of pri-miR-92a. Disruption of the NPSL2 hairpin structure could promote the formation of a pri-miR-92a structure that is primed for processing by Drosha. Thus, NPSL2 is predicted to function as a structural switch, regulating pri-miR-92a processing. Here, we determined the solution structure of NPSL2 using solution NMR spectroscopy. This is the first high-resolution structure of an oncomiR-1 element. NPSL2 adopts a hairpin structure with a large, but highly structured, apical and internal loops. The 10-bp apical loop contains a pH-sensitive A+·C mismatch. Additionally, several adenosines within the apical and internal loops have elevated pKa values. The protonation of these adenosines can stabilize the NPSL2 structure through electrostatic interactions. Our study provides fundamental insights into the secondary and tertiary structure of an important RNA hairpin proposed to regulate miR biogenesis.
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Affiliation(s)
- Yaping Liu
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA. https://twitter.com/YapingLiu5
| | - Aldrex Munsayac
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA
| | - Ian Hall
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA. https://twitter.com/ihallu14
| | - Sarah C Keane
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA; Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA.
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13
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Focht CM, Strobel SA. Efficient quantitative monitoring of translational initiation by RelE cleavage. Nucleic Acids Res 2022; 50:e105. [PMID: 35871288 PMCID: PMC9561414 DOI: 10.1093/nar/gkac614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 06/23/2022] [Accepted: 07/19/2022] [Indexed: 11/14/2022] Open
Abstract
Abstract
The sequences of the 5′ untranslated regions (5′-UTRs) of mRNA alter gene expression across domains of life. Transcriptional modulators can be easily assayed through transcription termination, but translational regulators often require indirect, laborious methods. We have leveraged RelE’s ribosome-dependent endonuclease activity to develop a quantitative assay to monitor translation initiation of cis-regulatory mRNAs. RelE cleavage accurately reports ligand-dependent changes in ribosome association for two translational riboswitches and provides quantitative information about each switch's sensitivity and range of response. RelE accurately reads out sequence-driven changes in riboswitch specificity and function and is quantitatively dependent upon ligand concentration. RelE cleavage similarly captures differences in translation initiation between yeast 5′-UTR isoforms. RelE cleavage can thus reveal a plethora of information about translation initiation in different domains of life.
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Affiliation(s)
- Caroline M Focht
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven , CT 06510 , USA
- Institute of Biomolecular Design and Discovery , West Haven , CT 06516 , USA
| | - Scott A Strobel
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven , CT 06510 , USA
- Institute of Biomolecular Design and Discovery , West Haven , CT 06516 , USA
- Department of Chemistry, Yale University , New Haven , CT 06511 , USA
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14
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Fuks C, Falkner S, Schwierz N, Hengesbach M. Combining Coarse-Grained Simulations and Single Molecule Analysis Reveals a Three-State Folding Model of the Guanidine-II Riboswitch. Front Mol Biosci 2022; 9:826505. [PMID: 35573739 PMCID: PMC9094411 DOI: 10.3389/fmolb.2022.826505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Riboswitch RNAs regulate gene expression by conformational changes induced by environmental conditions and specific ligand binding. The guanidine-II riboswitch is proposed to bind the small molecule guanidinium and to subsequently form a kissing loop interaction between the P1 and P2 hairpins. While an interaction was shown for isolated hairpins in crystallization and electron paramagnetic resonance experiments, an intrastrand kissing loop formation has not been demonstrated. Here, we report the first evidence of this interaction in cis in a ligand and Mg2+ dependent manner. Using single-molecule FRET spectroscopy and detailed structural information from coarse-grained simulations, we observe and characterize three interconvertible states representing an open and kissing loop conformation as well as a novel Mg2+ dependent state for the guanidine-II riboswitch from E. coli. The results further substantiate the proposed switching mechanism and provide detailed insight into the regulation mechanism for the guanidine-II riboswitch class. Combining single molecule experiments and coarse-grained simulations therefore provides a promising perspective in resolving the conformational changes induced by environmental conditions and to yield molecular insights into RNA regulation.
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Affiliation(s)
- Christin Fuks
- Institute for Organic Chemistry and Chemical Biology, Goethe-University Frankfurt, Frankfurt am Main, Germany
| | - Sebastian Falkner
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.,Computational and Soft Matter Physics, University of Vienna, Vienna, VIA, Austria
| | - Nadine Schwierz
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Martin Hengesbach
- Institute for Organic Chemistry and Chemical Biology, Goethe-University Frankfurt, Frankfurt am Main, Germany
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15
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Schamber T, Binas O, Schlundt A, Wacker A, Schwalbe H. Characterization of Structure and Dynamics of the Guanidine-II Riboswitch from Escherichia coli by NMR Spectroscopy and Small-Angle X-ray Scattering (SAXS). Chembiochem 2022; 23:e202100564. [PMID: 34847270 PMCID: PMC9300104 DOI: 10.1002/cbic.202100564] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/30/2021] [Indexed: 11/12/2022]
Abstract
Riboswitches are regulatory RNA elements that undergo functionally important allosteric conformational switching upon binding of specific ligands. The here investigated guanidine-II riboswitch binds the small cation, guanidinium, and forms a kissing loop-loop interaction between its P1 and P2 hairpins. We investigated the structural changes to support previous studies regarding the binding mechanism. Using NMR spectroscopy, we confirmed the structure as observed in crystal structures and we characterized the kissing loop interaction upon addition of Mg2+ and ligand for the riboswitch aptamer from Escherichia coli. We further investigated closely related mutant constructs providing further insight into functional differences between the two (different) hairpins P1 and P2. Formation of intermolecular interactions were probed by small-angle X-ray scattering (SAXS) and NMR DOSY data. All data are consistent and show the formation of oligomeric states of the riboswitch induced by Mg2+ and ligand binding.
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Affiliation(s)
- Tatjana Schamber
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Oliver Binas
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Andreas Schlundt
- Institute for Molecular BiosciencesJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 960438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 760438Frankfurt/MainGermany
- Center for Biomolecular Magnetic ResonanceInstitute for Organic Chemistry and Chemical BiologyJohann Wolfgang Goethe UniversityMax-von-Laue-Str. 7–960438Frankfurt/MainGermany
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16
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A small RNA that cooperatively senses two stacked metabolites in one pocket for gene control. Nat Commun 2022; 13:199. [PMID: 35017488 PMCID: PMC8752633 DOI: 10.1038/s41467-021-27790-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 12/02/2021] [Indexed: 11/16/2022] Open
Abstract
Riboswitches are structured non-coding RNAs often located upstream of essential genes in bacterial messenger RNAs. Such RNAs regulate expression of downstream genes by recognizing a specific cellular effector. Although nearly 50 riboswitch classes are known, only a handful recognize multiple effectors. Here, we report the 2.60-Å resolution co-crystal structure of a class I type I preQ1-sensing riboswitch that reveals two effectors stacked atop one another in a single binding pocket. These effectors bind with positive cooperativity in vitro and both molecules are necessary for gene regulation in bacterial cells. Stacked effector recognition appears to be a hallmark of the largest subgroup of preQ1 riboswitches, including those from pathogens such as Neisseria gonorrhoeae. We postulate that binding to stacked effectors arose in the RNA World to closely position two substrates for RNA-mediated catalysis. These findings expand known effector recognition capabilities of riboswitches and have implications for antimicrobial development. Riboswitches contain an aptamer domain that recognizes a metabolite and an expression platform that regulates gene expression. Here the authors report the crystal structure of a preQ1-sensing riboswitch from Carnobacterium antarcticus that shows two metabolites in a single binding pocket.
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17
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Sherlock ME, Higgs G, Yu D, Widner DL, White NA, Sudarsan N, Sadeeshkumar H, Perkins KR, Mirihana Arachchilage G, Malkowski SN, King CG, Harris KA, Gaffield G, Atilho RM, Breaker RR. Architectures and complex functions of tandem riboswitches. RNA Biol 2022; 19:1059-1076. [PMID: 36093908 PMCID: PMC9481103 DOI: 10.1080/15476286.2022.2119017] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/23/2022] [Indexed: 11/16/2022] Open
Abstract
Riboswitch architectures that involve the binding of a single ligand to a single RNA aptamer domain result in ordinary dose-response curves that require approximately a 100-fold change in ligand concentration to cover nearly the full dynamic range for gene regulation. However, by using multiple riboswitches or aptamer domains in tandem, these ligand-sensing structures can produce additional, complex gene control outcomes. In the current study, we have computationally searched for tandem riboswitch architectures in bacteria to provide a more complete understanding of the diverse biological and biochemical functions of gene control elements that are made exclusively of RNA. Numerous different arrangements of tandem homologous riboswitch architectures are exploited by bacteria to create more 'digital' gene control devices, which operate over a narrower ligand concentration range. Also, two heterologous riboswitch aptamers are sometimes employed to create two-input Boolean logic gates with various types of genetic outputs. These findings illustrate the sophisticated genetic decisions that can be made by using molecular sensors and switches based only on RNA.
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Affiliation(s)
- Madeline E. Sherlock
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado, Anschutz Medical Campus, Research-1S, Aurora, CO, USA
| | - Gadareth Higgs
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Diane Yu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Danielle L. Widner
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Neil A. White
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | | | - Harini Sadeeshkumar
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Kevin R. Perkins
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Gayan Mirihana Arachchilage
- Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
- PTC Therapeutics, Inc, South Plainfield, NJ, USA
| | | | - Christopher G. King
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | | | - Glenn Gaffield
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Ruben M. Atilho
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Ronald R. Breaker
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
- Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
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18
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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: 9] [Impact Index Per Article: 2.3] [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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19
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Siblings or doppelgängers? Deciphering the evolution of structured cis-regulatory RNAs beyond homology. Biochem Soc Trans 2021; 48:1941-1951. [PMID: 32869842 PMCID: PMC7609027 DOI: 10.1042/bst20191060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/04/2020] [Accepted: 08/06/2020] [Indexed: 11/21/2022]
Abstract
Structured cis-regulatory RNAs have evolved across all domains of life, highlighting the utility and plasticity of RNA as a regulatory molecule. Homologous RNA sequences and structures often have similar functions, but homology may also be deceiving. The challenges that derive from trying to assign function to structure and vice versa are not trivial. Bacterial riboswitches, viral and eukaryotic IRESes, CITEs, and 3′ UTR elements employ an array of mechanisms to exert their effects. Bioinformatic searches coupled with biochemical and functional validation have elucidated some shared and many unique ways cis-regulators are employed in mRNA transcripts. As cis-regulatory RNAs are resolved in greater detail, it is increasingly apparent that shared homology can mask the full spectrum of mRNA cis-regulator functional diversity. Furthermore, similar functions may be obscured by lack of obvious sequence similarity. Thus looking beyond homology is crucial for furthering our understanding of RNA-based regulation.
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20
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Steuer J, Kukharenko O, Riedmiller K, Hartig JS, Peter C. Guanidine-II aptamer conformations and ligand binding modes through the lens of molecular simulation. Nucleic Acids Res 2021; 49:7954-7965. [PMID: 34233001 PMCID: PMC8373139 DOI: 10.1093/nar/gkab592] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 12/01/2022] Open
Abstract
Regulation of gene expression via riboswitches is a widespread mechanism in bacteria. Here, we investigate ligand binding of a member of the guanidine sensing riboswitch family, the guanidine-II riboswitch (Gd-II). It consists of two stem–loops forming a dimer upon ligand binding. Using extensive molecular dynamics simulations we have identified conformational states corresponding to ligand-bound and unbound states in a monomeric stem–loop of Gd-II and studied the selectivity of this binding. To characterize these states and ligand-dependent conformational changes we applied a combination of dimensionality reduction, clustering, and feature selection methods. In absence of a ligand, the shape of the binding pocket alternates between the conformation observed in presence of guanidinium and a collapsed conformation, which is associated with a deformation of the dimerization interface. Furthermore, the structural features responsible for the ability to discriminate against closely related analogs of guanidine are resolved. Based on these insights, we propose a mechanism that couples ligand binding to aptamer dimerization in the Gd-II system, demonstrating the value of computational methods in the field of nucleic acids research.
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Affiliation(s)
- Jakob Steuer
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
| | - Oleksandra Kukharenko
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.,Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Kai Riedmiller
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Jörg S Hartig
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
| | - Christine Peter
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457 Konstanz, Germany
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21
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Law ASY, Lee LCC, Lo KKW, Yam VWW. Aggregation and Supramolecular Self-Assembly of Low-Energy Red Luminescent Alkynylplatinum(II) Complexes for RNA Detection, Nucleolus Imaging, and RNA Synthesis Inhibitor Screening. J Am Chem Soc 2021; 143:5396-5405. [PMID: 33813827 DOI: 10.1021/jacs.0c13327] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
As an important nuclear substructure, the nucleolus has received increasing attention because of its significant functions in the transcription and processing of ribosomal RNA in eukaryotic cells. In this work, we introduce a proof-of-concept luminescence assay to detect RNA and to accomplish nucleolus imaging with the use of the supramolecular self-assembly of platinum(II) complexes. Noncovalent interactions between platinum(II) complexes and RNA can be induced by the introduction of a guanidinium group into the complexes, and accordingly, a high RNA affinity can be achieved. Interestingly, the aggregation affinities of platinum(II) complexes enable them to display remarkable luminescence turn-on upon RNA binding, which is a result of the strengthening of noncovalent Pt(II)···Pt(II) and π-π stacking interactions. The complexes exhibit not only intriguing spectroscopic changes and luminescence enhancement after RNA binding but also specific nucleolus imaging in cells. As compared to fluorescent dyes, the low-energy red luminescence and large Stokes shifts of platinum(II) complexes afford a high signal-to-background autofluorescence ratio in nucleolus imaging. Additional properties, including long phosphorescence lifetimes and low cytotoxicity, have endowed the platinum(II) complexes with the potential for biological applications. Also, platinum(II) complexes have been adopted to monitor the dynamics of the nucleolus induced by the addition of RNA synthesis inhibitors. This capability allows the screening of inhibitors and can be advantageous for the development of antineoplastic agents. This work provides a novel strategy for exploring the application of platinum(II) complex-based cell imaging agents based on the mechanism of supramolecular self-assembly. It is envisaged that platinum(II) complexes can be utilized as valuable probes because of the aforementioned appealing advantages.
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Affiliation(s)
- Angela Sin-Yee Law
- Institute of Molecular Functional Materials, State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Lawrence Cho-Cheung Lee
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| | - Kenneth Kam-Wing Lo
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China
| | - Vivian Wing-Wah Yam
- Institute of Molecular Functional Materials, State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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22
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Lenkeit F, Eckert I, Hartig JS, Weinberg Z. Discovery and characterization of a fourth class of guanidine riboswitches. Nucleic Acids Res 2021; 48:12889-12899. [PMID: 33237283 PMCID: PMC7736828 DOI: 10.1093/nar/gkaa1102] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/20/2020] [Accepted: 10/28/2020] [Indexed: 12/20/2022] Open
Abstract
Riboswitches are RNAs that specifically sense a small molecule and regulate genes accordingly. The recent discovery of guanidine-binding riboswitches revealed the biological significance of this compound, and uncovered genes related to its biology. For example, certain sugE genes encode guanidine exporters and are activated by the riboswitches to reduce toxic levels of guanidine in the cell. In order to study guanidine biology and riboswitches, we applied a bioinformatics strategy for discovering additional guanidine riboswitches by searching for new candidate motifs associated with sugE genes. Based on in vitro and in vivo experiments, we determined that one of our six best candidates is a new structural class of guanidine riboswitches. The expression of a genetic reporter was induced 80-fold in response to addition of 5 mM guanidine in Staphylococcus aureus. This new class, called the guanidine-IV riboswitch, reveals additional guanidine-associated protein domains that are extremely rarely or never associated with previously established guanidine riboswitches. Among these protein domains are two transporter families that are structurally distinct from SugE, and could represent novel types of guanidine exporters. These results establish a new metabolite-binding RNA, further validate a bioinformatics method for finding riboswitches and suggest substrate specificities for as-yet uncharacterized transporter proteins.
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Affiliation(s)
- Felina Lenkeit
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Iris Eckert
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107 Leipzig, Germany
| | - Jörg S Hartig
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Zasha Weinberg
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16-18, 04107 Leipzig, Germany
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23
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Broft P, Dzatko S, Krafcikova M, Wacker A, Hänsel‐Hertsch R, Dötsch V, Trantirek L, Schwalbe H. In-Cell NMR Spectroscopy of Functional Riboswitch Aptamers in Eukaryotic Cells. Angew Chem Int Ed Engl 2021; 60:865-872. [PMID: 32975353 PMCID: PMC7839747 DOI: 10.1002/anie.202007184] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/22/2020] [Indexed: 12/14/2022]
Abstract
We report here the in-cell NMR-spectroscopic observation of the binding of the cognate ligand 2'-deoxyguanosine to the aptamer domain of the bacterial 2'-deoxyguanosine-sensing riboswitch in eukaryotic cells, namely Xenopus laevis oocytes and in human HeLa cells. The riboswitch is sufficiently stable in both cell types to allow for detection of binding of the ligand to the riboswitch. Most importantly, we show that the binding mode established by in vitro characterization of this prokaryotic riboswitch is maintained in eukaryotic cellular environment. Our data also bring important methodological insights: Thus far, in-cell NMR studies on RNA in mammalian cells have been limited to investigations of short (<15 nt) RNA fragments that were extensively modified by protecting groups to limit their degradation in the intracellular space. Here, we show that the in-cell NMR setup can be adjusted for characterization of much larger (≈70 nt) functional and chemically non-modified RNA.
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Affiliation(s)
- P. Broft
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute for Organic Chemistry and Chemical BiologyGoethe UniversityMax-von-Laue-Str. 760438Frankfurt/M.Germany
| | - S. Dzatko
- National Centre for Biomolecular ResearchMasaryk UniversityKamenice 5625 00BrnoCzech Republic
- Central European Institute of Technology (CEITEC)Masaryk UniversityKamenice 753/5625 00BrnoCzech Republic
| | - M. Krafcikova
- National Centre for Biomolecular ResearchMasaryk UniversityKamenice 5625 00BrnoCzech Republic
- Institute of BiophysicsCzech Academy of SciencesKralovopolska 135612 65BrnoCzech Republic
| | - A. Wacker
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute for Organic Chemistry and Chemical BiologyGoethe UniversityMax-von-Laue-Str. 760438Frankfurt/M.Germany
| | - Robert Hänsel‐Hertsch
- Present address: Center for Molecular Medicine CologneRobert-Koch-Str. 2150931CologneGermany
| | - Volker Dötsch
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute of Biophysical ChemistryGoethe UniversityMax-von-Laue-Str. 960438Frankfurt/M.Germany
| | - L. Trantirek
- Central European Institute of Technology (CEITEC)Masaryk UniversityKamenice 753/5625 00BrnoCzech Republic
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute for Organic Chemistry and Chemical BiologyGoethe UniversityMax-von-Laue-Str. 760438Frankfurt/M.Germany
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24
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Steckelberg AL, Vicens Q, Costantino DA, Nix JC, Kieft JS. The crystal structure of a Polerovirus exoribonuclease-resistant RNA shows how diverse sequences are integrated into a conserved fold. RNA (NEW YORK, N.Y.) 2020; 26:1767-1776. [PMID: 32848042 PMCID: PMC7668246 DOI: 10.1261/rna.076224.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/19/2020] [Indexed: 05/31/2023]
Abstract
Exoribonuclease-resistant RNAs (xrRNAs) are discrete elements that block the progression of 5' to 3' exoribonucleases using specifically folded RNA structures. A recently discovered class of xrRNA is widespread in several genera of plant-infecting viruses, within both noncoding and protein-coding subgenomic RNAs. The structure of one such xrRNA from a dianthovirus revealed three-dimensional details of the resistant fold but did not answer all questions regarding the conservation and diversity of this xrRNA class. Here, we present the crystal structure of a representative polerovirus xrRNA that contains sequence elements that diverge from the previously solved structure. This new structure rationalizes previously unexplained sequence conservation patterns and shows interactions not present in the first structure. Together, the structures of these xrRNAs from dianthovirus and polerovirus genera support the idea that these plant virus xrRNAs fold through a defined pathway that includes a programmed intermediate conformation. This work deepens our knowledge of the structure-function relationship of xrRNAs and shows how evolution can craft similar RNA folds from divergent sequences.
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Affiliation(s)
- Anna-Lena Steckelberg
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Quentin Vicens
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - David A Costantino
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Jay C Nix
- Molecular Biology Consortium, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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25
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Steckelberg AL, Vicens Q, Costantino DA, Nix JC, Kieft JS. The crystal structure of a Polerovirus exoribonuclease-resistant RNA shows how diverse sequences are integrated into a conserved fold. RNA (NEW YORK, N.Y.) 2020; 26:1767-1776. [PMID: 32848042 DOI: 10.1101/2020.04.30.070631] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/19/2020] [Indexed: 05/26/2023]
Abstract
Exoribonuclease-resistant RNAs (xrRNAs) are discrete elements that block the progression of 5' to 3' exoribonucleases using specifically folded RNA structures. A recently discovered class of xrRNA is widespread in several genera of plant-infecting viruses, within both noncoding and protein-coding subgenomic RNAs. The structure of one such xrRNA from a dianthovirus revealed three-dimensional details of the resistant fold but did not answer all questions regarding the conservation and diversity of this xrRNA class. Here, we present the crystal structure of a representative polerovirus xrRNA that contains sequence elements that diverge from the previously solved structure. This new structure rationalizes previously unexplained sequence conservation patterns and shows interactions not present in the first structure. Together, the structures of these xrRNAs from dianthovirus and polerovirus genera support the idea that these plant virus xrRNAs fold through a defined pathway that includes a programmed intermediate conformation. This work deepens our knowledge of the structure-function relationship of xrRNAs and shows how evolution can craft similar RNA folds from divergent sequences.
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Affiliation(s)
- Anna-Lena Steckelberg
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Quentin Vicens
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - David A Costantino
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Jay C Nix
- Molecular Biology Consortium, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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26
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The structural basis of promiscuity in small multidrug resistance transporters. Nat Commun 2020; 11:6064. [PMID: 33247110 PMCID: PMC7695847 DOI: 10.1038/s41467-020-19820-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/27/2020] [Indexed: 12/20/2022] Open
Abstract
By providing broad resistance to environmental biocides, transporters from the small multidrug resistance (SMR) family drive the spread of multidrug resistance cassettes among bacterial populations. A fundamental understanding of substrate selectivity by SMR transporters is needed to identify the types of selective pressures that contribute to this process. Using solid-supported membrane electrophysiology, we find that promiscuous transport of hydrophobic substituted cations is a general feature of SMR transporters. To understand the molecular basis for promiscuity, we solved X-ray crystal structures of a SMR transporter Gdx-Clo in complex with substrates to a maximum resolution of 2.3 Å. These structures confirm the family’s extremely rare dual topology architecture and reveal a cleft between two helices that provides accommodation in the membrane for the hydrophobic substituents of transported drug-like cations. Gdx-Clo is a bacterial transporter from the small multidrug resistance (SMR) family. Here, the authors use solid supported membrane electrophysiology to characterize Gdx-Clo functionally and report crystal structures of Gdx-Clo which confirm the dual topology architecture and offer insight into substrate binding and transport mechanism.
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27
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Salvail H, Balaji A, Yu D, Roth A, Breaker RR. Biochemical Validation of a Fourth Guanidine Riboswitch Class in Bacteria. Biochemistry 2020; 59:4654-4662. [PMID: 33236895 DOI: 10.1021/acs.biochem.0c00793] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
An intriguing consequence of ongoing riboswitch discovery efforts is the occasional identification of metabolic or toxicity response pathways for unusual ligands. Recently, we reported the experimental validation of three distinct bacterial riboswitch classes that regulate gene expression in response to the selective binding of a guanidinium ion. These riboswitch classes, called guanidine-I, -II, and -III, regulate numerous genes whose protein products include previously misannotated guanidine exporters and enzymes that degrade guanidine via an initial carboxylation reaction. Guanidine is now recognized as the primal substrate of many multidrug efflux pumps that are important for bacterial resistance to certain antibiotics. Guanidine carboxylase enzymes had long been annotated as urea carboxylase enzymes but are now understood to participate in guanidine degradation. Herein, we report the existence of a fourth riboswitch class for this ligand, called guanidine-IV. Members of this class use a novel aptamer to selectively bind guanidine and use an unusual expression platform arrangement that is predicted to activate gene expression when ligand is present. The wide distribution of this abundant riboswitch class, coupled with the striking diversity of other guanidine-sensing RNAs, demonstrates that many bacterial species maintain sophisticated sensory and genetic mechanisms to avoid guanidine toxicity. This finding further highlights the mystery regarding the natural source of this nitrogen-rich chemical moiety.
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Affiliation(s)
- Hubert Salvail
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, United States
| | - Aparaajita Balaji
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, United States
| | - Diane Yu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, United States
| | - Adam Roth
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, United States
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, United States.,Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, United States
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28
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Broft P, Dzatko S, Krafcikova M, Wacker A, Hänsel‐Hertsch R, Dötsch V, Trantirek L, Schwalbe H. In‐Cell NMR Spectroscopy of Functional Riboswitch Aptamers in Eukaryotic Cells. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- P. Broft
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute for Organic Chemistry and Chemical Biology Goethe University Max-von-Laue-Str. 7 60438 Frankfurt/M. Germany
| | - S. Dzatko
- National Centre for Biomolecular Research Masaryk University Kamenice 5 625 00 Brno Czech Republic
- Central European Institute of Technology (CEITEC) Masaryk University Kamenice 753/5 625 00 Brno Czech Republic
| | - M. Krafcikova
- National Centre for Biomolecular Research Masaryk University Kamenice 5 625 00 Brno Czech Republic
- Institute of Biophysics Czech Academy of Sciences Kralovopolska 135 612 65 Brno Czech Republic
| | - A. Wacker
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute for Organic Chemistry and Chemical Biology Goethe University Max-von-Laue-Str. 7 60438 Frankfurt/M. Germany
| | - Robert Hänsel‐Hertsch
- Present address: Center for Molecular Medicine Cologne Robert-Koch-Str. 21 50931 Cologne Germany
| | - Volker Dötsch
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute of Biophysical Chemistry Goethe University Max-von-Laue-Str. 9 60438 Frankfurt/M. Germany
| | - L. Trantirek
- Central European Institute of Technology (CEITEC) Masaryk University Kamenice 753/5 625 00 Brno Czech Republic
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute for Organic Chemistry and Chemical Biology Goethe University Max-von-Laue-Str. 7 60438 Frankfurt/M. Germany
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29
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Slipski CJ, Jamieson TR, Zhanel GG, Bay DC. Riboswitch-Associated Guanidinium-Selective Efflux Pumps Frequently Transmitted on Proteobacterial Plasmids Increase Escherichia coli Biofilm Tolerance to Disinfectants. J Bacteriol 2020; 202:e00104-20. [PMID: 32928929 PMCID: PMC7648145 DOI: 10.1128/jb.00104-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 09/08/2020] [Indexed: 12/13/2022] Open
Abstract
Members of the small multidrug resistance (SMR) efflux pump family known as SugE (recently renamed Gdx) are known for their narrow substrate selectivity to small guanidinium (Gdm+) compounds and disinfectant quaternary ammonium compounds (QACs). Gdx members have been identified on multidrug resistance plasmids in Gram-negative bacilli, but their functional role remains unclear, as few have been characterized. Here, we conducted a survey of sequenced proteobacterial plasmids that encoded one or more SugE/Gdx sequences in an effort to (i) identify the most frequently represented Gdx member(s) on these plasmids and their sequence diversity, (ii) verify if Gdx sequences possess a Gdm+ riboswitch that regulates their translation similarly to chromosomally encoded Gdx members, and (iii) determine the antimicrobial susceptibility profile of the most predominate Gdx member to various QACs and antibiotics in Escherichia coli strains BW25113 and KAM32. The results of this study determined 14 unique SugE sequences, but only one Gdx sequence, annotated as "SugE(p)," predominated among the >140 plasmids we surveyed. Enterobacterales plasmids carrying sugE(p) possessed a guanidine II riboswitch similar to the upstream region of E. coligdx Cloning and expression of sugE(p), gdx, and emrE sequences into a low-copy-number expression vector (pMS119EH) revealed significant increases in QAC resistance to a limited range of detergent-like QACs only when gdx and sugE(p) transformants were grown as biofilms. These findings suggest that sugE(p) presence on proteobacterial plasmids may be driven by species that frequently encounter Gdm+ and QAC exposure.IMPORTANCE This study characterized the function of antimicrobial-resistant phenotypes attributed to plasmid-encoded guanidinium-selective small multidrug resistance (Gdm/SugE) efflux pumps. These sequences are frequently monitored as biocide resistance markers in antimicrobial resistance surveillance studies. Our findings reveal that enterobacterial gdm sequences transmitted on plasmids possess a guanidine II riboswitch, which restricts transcript translation in the presence of guanidinium. Cloning and overexpression of this gdm sequence revealed that it confers higher resistance to quaternary ammonium compound (QAC) disinfectants (which possess guanidium moieties) when grown as biofilms. Since biofilms are commonly eradicated with QAC-containing compounds, the presence of this gene on plasmids and its biofilm-specific resistance are a growing concern for clinical and food safety prevention measures.
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Affiliation(s)
- Carmine J Slipski
- University of Manitoba, Medical Microbiology and Infectious Disease, Winnipeg, Manitoba, Canada
| | - Taylor R Jamieson
- University of Manitoba, Medical Microbiology and Infectious Disease, Winnipeg, Manitoba, Canada
| | - George G Zhanel
- University of Manitoba, Medical Microbiology and Infectious Disease, Winnipeg, Manitoba, Canada
| | - Denice C Bay
- University of Manitoba, Medical Microbiology and Infectious Disease, Winnipeg, Manitoba, Canada
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30
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Wuebben C, Vicino MF, Mueller M, Schiemann O. Do the P1 and P2 hairpins of the Guanidine-II riboswitch interact? Nucleic Acids Res 2020; 48:10518-10526. [PMID: 32857846 PMCID: PMC7544219 DOI: 10.1093/nar/gkaa703] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/08/2020] [Accepted: 08/12/2020] [Indexed: 01/09/2023] Open
Abstract
Riboswitches regulate genes by adopting different structures in responds to metabolite binding. The guanidine-II riboswitch is the smallest representative of the ykkC class with the mechanism of its function being centred on the idea that its two stem loops P1 and P2 form a kissing hairpin interaction upon binding of guanidinium (Gdm+). This mechanism is based on in-line probing experiments with the full-length riboswitch and crystal structures of the truncated stem loops P1 and P2. However, the crystal structures reveal only the formation of the homodimers P1 | P1 and P2 | P2 but not of the proposed heterodimer P1 | P2. Here, site-directed spin labeling (SDSL) in combination with Pulsed Electron–Electron Double Resonance (PELDOR or DEER) is used to study their structures in solution and how they change upon binding of Gdm+. It is found that both hairpins adopt different structures in solution and that binding of Gdm+ does indeed lead to the formation of the heterodimer but alongside the homodimers in a statistical 1:2:1 fashion. These results do thus support the proposed switching mechanism.
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Affiliation(s)
- Christine Wuebben
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Maria F Vicino
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Marcel Mueller
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
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31
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Miao Z, Adamiak RW, Antczak M, Boniecki MJ, Bujnicki J, Chen SJ, Cheng CY, Cheng Y, Chou FC, Das R, Dokholyan NV, Ding F, Geniesse C, Jiang Y, Joshi A, Krokhotin A, Magnus M, Mailhot O, Major F, Mann TH, Piątkowski P, Pluta R, Popenda M, Sarzynska J, Sun L, Szachniuk M, Tian S, Wang J, Wang J, Watkins AM, Wiedemann J, Xiao Y, Xu X, Yesselman JD, Zhang D, Zhang Y, Zhang Z, Zhao C, Zhao P, Zhou Y, Zok T, Żyła A, Ren A, Batey RT, Golden BL, Huang L, Lilley DM, Liu Y, Patel DJ, Westhof E. RNA-Puzzles Round IV: 3D structure predictions of four ribozymes and two aptamers. RNA (NEW YORK, N.Y.) 2020; 26:982-995. [PMID: 32371455 PMCID: PMC7373991 DOI: 10.1261/rna.075341.120] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/03/2020] [Indexed: 05/21/2023]
Abstract
RNA-Puzzles is a collective endeavor dedicated to the advancement and improvement of RNA 3D structure prediction. With agreement from crystallographers, the RNA structures are predicted by various groups before the publication of the crystal structures. We now report the prediction of 3D structures for six RNA sequences: four nucleolytic ribozymes and two riboswitches. Systematic protocols for comparing models and crystal structures are described and analyzed. In these six puzzles, we discuss (i) the comparison between the automated web servers and human experts; (ii) the prediction of coaxial stacking; (iii) the prediction of structural details and ligand binding; (iv) the development of novel prediction methods; and (v) the potential improvements to be made. We show that correct prediction of coaxial stacking and tertiary contacts is essential for the prediction of RNA architecture, while ligand binding modes can only be predicted with low resolution and simultaneous prediction of RNA structure with accurate ligand binding still remains out of reach. All the predicted models are available for the future development of force field parameters and the improvement of comparison and assessment tools.
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Affiliation(s)
- Zhichao Miao
- Translational Research Institute of Brain and Brain-Like Intelligence and Department of Anesthesiology, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai 200081, China
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, CB10 1SD, United Kingdom
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Ryszard W Adamiak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
- Institute of Computing Science, Poznan University of Technology, 60-965 Poznan, Poland
| | - Maciej Antczak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
- Institute of Computing Science, Poznan University of Technology, 60-965 Poznan, Poland
| | - Michał J Boniecki
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Janusz Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Shi-Jie Chen
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Clarence Yu Cheng
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Yi Cheng
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Fang-Chieh Chou
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania, 17033, USA
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, Pennsylvania, 17033, USA
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Caleb Geniesse
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Yangwei Jiang
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Astha Joshi
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Andrey Krokhotin
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Departments of Pathology, Genetics and Developmental Biology, Howard Hughes Medical Institute, Stanford Medical School, Palo Alto, California, 94305, USA
| | - Marcin Magnus
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Olivier Mailhot
- Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Francois Major
- Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Thomas H Mann
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Paweł Piątkowski
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Radoslaw Pluta
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Mariusz Popenda
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
| | - Joanna Sarzynska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
| | - Lizhen Sun
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Marta Szachniuk
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
- Institute of Computing Science, Poznan University of Technology, 60-965 Poznan, Poland
| | - Siqi Tian
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Jian Wang
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania, 17033, USA
| | - Jun Wang
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
| | - Andrew M Watkins
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Jakub Wiedemann
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznan, Poland
- Institute of Computing Science, Poznan University of Technology, 60-965 Poznan, Poland
| | - Yi Xiao
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
| | - Xiaojun Xu
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Joseph D Yesselman
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Dong Zhang
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Yi Zhang
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
| | - Zhenzhen Zhang
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Chenhan Zhao
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Peinan Zhao
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Yuanzhe Zhou
- Department of Physics and Astronomy, Department of Biochemistry, MU Institute for Data Science and Informatics, University of Missouri-Columbia, Missouri 65211, USA
| | - Tomasz Zok
- Institute of Computing Science, Poznan University of Technology, 60-965 Poznan, Poland
| | - Adriana Żyła
- International Institute of Molecular and Cell Biology in Warsaw, Księcia Trojdena 4, 02-109 Warsaw, Poland
| | - Aiming Ren
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Robert T Batey
- Department of Biochemistry, University of Colorado at Boulder, Campus Box 596, Boulder, Colorado 80309-0596, USA
| | - Barbara L Golden
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - 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, United Kingdom
| | - David M Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | - Yijin Liu
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Eric Westhof
- Arch et Reactivite de l'ARN, Univ de Strasbourg, Inst de Biol Mol et Cell du CNRS, 67084 Strasbourg, France
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32
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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: 0.6] [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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33
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Structural Insights into RNA Dimerization: Motifs, Interfaces and Functions. Molecules 2020; 25:molecules25122881. [PMID: 32585844 PMCID: PMC7357161 DOI: 10.3390/molecules25122881] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022] Open
Abstract
In comparison with the pervasive use of protein dimers and multimers in all domains of life, functional RNA oligomers have so far rarely been observed in nature. Their diminished occurrence contrasts starkly with the robust intrinsic potential of RNA to multimerize through long-range base-pairing ("kissing") interactions, self-annealing of palindromic or complementary sequences, and stable tertiary contact motifs, such as the GNRA tetraloop-receptors. To explore the general mechanics of RNA dimerization, we performed a meta-analysis of a collection of exemplary RNA homodimer structures consisting of viral genomic elements, ribozymes, riboswitches, etc., encompassing both functional and fortuitous dimers. Globally, we found that domain-swapped dimers and antiparallel, head-to-tail arrangements are predominant architectural themes. Locally, we observed that the same structural motifs, interfaces and forces that enable tertiary RNA folding also drive their higher-order assemblies. These feature prominently long-range kissing loops, pseudoknots, reciprocal base intercalations and A-minor interactions. We postulate that the scarcity of functional RNA multimers and limited diversity in multimerization motifs may reflect evolutionary constraints imposed by host antiviral immune surveillance and stress sensing. A deepening mechanistic understanding of RNA multimerization is expected to facilitate investigations into RNA and RNP assemblies, condensates, and granules and enable their potential therapeutical targeting.
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Sherlock ME, Breaker RR. Former orphan riboswitches reveal unexplored areas of bacterial metabolism, signaling, and gene control processes. RNA (NEW YORK, N.Y.) 2020; 26:675-693. [PMID: 32165489 PMCID: PMC7266159 DOI: 10.1261/rna.074997.120] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Comparative sequence analyses have been used to discover numerous classes of structured noncoding RNAs, some of which are riboswitches that specifically recognize small-molecule or elemental ion ligands and influence expression of adjacent downstream genes. Determining the correct identity of the ligand for a riboswitch candidate typically is aided by an understanding of the genes under its regulatory control. Riboswitches whose ligands were straightforward to identify have largely been associated with well-characterized metabolic pathways, such as coenzyme or amino acid biosynthesis. Riboswitch candidates whose ligands resist identification, collectively known as orphan riboswitches, are often associated with genes coding for proteins of unknown function, or genes for various proteins with no established link to one another. The cognate ligands for 16 former orphan riboswitch motifs have been identified to date. The successful pursuit of the ligands for these classes has provided insight into areas of biology that are not yet fully explored, such as ion homeostasis, signaling networks, and other previously underappreciated biochemical or physiological processes. Herein we discuss the strategies and methods used to match ligands with orphan riboswitch classes, and overview the lessons learned to inform and motivate ongoing efforts to identify ligands for the many remaining candidates.
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Affiliation(s)
- Madeline E Sherlock
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Ronald R Breaker
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520, USA
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35
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Mitchell C, Polanco JA, DeWald L, Kress D, Jaeger L, Grabow WW. Responsive self-assembly of tectoRNAs with loop-receptor interactions from the tetrahydrofolate (THF) riboswitch. Nucleic Acids Res 2020; 47:6439-6451. [PMID: 31045210 PMCID: PMC6614920 DOI: 10.1093/nar/gkz304] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 03/22/2019] [Accepted: 04/16/2019] [Indexed: 12/17/2022] Open
Abstract
Naturally occurring RNAs are known to exhibit a high degree of modularity, whereby specific structural modules (or motifs) can be mixed and matched to create new molecular architectures. The modular nature of RNA also affords researchers the ability to characterize individual structural elements in controlled synthetic contexts in order to gain new and critical insights into their particular structural features and overall performance. Here, we characterized the binding affinity of a unique loop–receptor interaction found in the tetrahydrofolate (THF) riboswitch using rationally designed self-assembling tectoRNAs. Our work suggests that the THF loop–receptor interaction has been fine-tuned for its particular role as a riboswitch component. We also demonstrate that the thermodynamic stability of this interaction can be modulated by the presence of folinic acid, which induces a local structural change at the level of the loop–receptor. This corroborates the existence of a THF binding site within this tertiary module and paves the way for its potential use as a THF responsive module for RNA nanotechnology and synthetic biology.
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Affiliation(s)
- Charles Mitchell
- Department of Chemistry and Biochemistry, Seattle Pacific University, Seattle, WA 918119-1997, USA
| | - Julio A Polanco
- Department of Chemistry and Biochemistry, Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9510, USA
| | - Laura DeWald
- Department of Chemistry and Biochemistry, Seattle Pacific University, Seattle, WA 918119-1997, USA
| | - Dustin Kress
- Department of Chemistry and Biochemistry, Seattle Pacific University, Seattle, WA 918119-1997, USA
| | - Luc Jaeger
- Department of Chemistry and Biochemistry, Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9510, USA
| | - Wade W Grabow
- Department of Chemistry and Biochemistry, Seattle Pacific University, Seattle, WA 918119-1997, USA
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36
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Huang L, Wang J, Watkins AM, Das R, Lilley DMJ. Structure and ligand binding of the glutamine-II riboswitch. Nucleic Acids Res 2019; 47:7666-7675. [PMID: 31216023 PMCID: PMC6698751 DOI: 10.1093/nar/gkz539] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/31/2019] [Accepted: 06/06/2019] [Indexed: 12/14/2022] Open
Abstract
We have determined the structure of the glutamine-II riboswitch ligand binding domain using X-ray crystallography. The structure was solved using a novel combination of homology modeling and molecular replacement. The structure comprises three coaxial helical domains, the central one of which is a pseudoknot with partial triplex character. The major groove of this helix provides the binding site for L-glutamine, which is extensively hydrogen bonded to the RNA. Atomic mutation of the RNA at the ligand binding site leads to loss of binding shown by isothermal titration calorimetry, explaining the specificity of the riboswitch. A metal ion also plays an important role in ligand binding. This is directly bonded to a glutamine carboxylate oxygen atom, and its remaining inner-sphere water molecules make hydrogen bonding interactions with the RNA.
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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
| | - Jia Wang
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Andrew M Watkins
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, 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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37
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Guanidine Riboswitch-Regulated Efflux Transporters Protect Bacteria against Ionic Liquid Toxicity. J Bacteriol 2019; 201:JB.00069-19. [PMID: 30988034 DOI: 10.1128/jb.00069-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/09/2019] [Indexed: 11/20/2022] Open
Abstract
Plant cell walls contain a renewable, nearly limitless supply of sugar that could be used to support microbial production of commodity chemicals and biofuels. Imidazolium ionic liquid (IIL) solvents are among the best reagents for gaining access to the sugars in this otherwise recalcitrant biomass. However, the sugars from IIL-treated biomass are inevitably contaminated with residual IILs that inhibit growth in bacteria and yeast, blocking biochemical production by these organisms. IIL toxicity is, therefore, a critical roadblock in many industrial biosynthetic pathways. Although several IIL-tolerant (IILT) bacterial and yeast isolates have been identified in nature, few genetic mechanisms have been identified. In this study, we identified two IILT Bacillus isolates as well as a spontaneous IILT Escherichia coli lab strain that are tolerant to high levels of two widely used IILs. We demonstrate that all three IILT strains contain one or more pumps of the small multidrug resistance (SMR) family, and two of these strains contain mutations that affect an adjacent regulatory guanidine riboswitch. Furthermore, we show that the regulation of E. coli sugE by the guanidine II riboswitch can be exploited to promote IIL tolerance by the simple addition of guanidine to the medium. Our results demonstrate the critical role that transporter genes play in IIL tolerance in their native bacterial hosts. The study presented here is another step in engineering IIL tolerance into industrial strains toward overcoming this key gap in biofuels and industrial biochemical production processes.IMPORTANCE This study identifies bacteria that are tolerant to ionic liquid solvents used in the production of biofuels and industrial biochemicals. For industrial microbiology, it is essential to find less-harmful reagents and microbes that are resistant to their cytotoxic effects. We identified a family of small multidrug resistance efflux transporters, which are responsible for the tolerance of these strains. We also found that this resistance can be caused by mutations in the sequences of guanidine-specific riboswitches that regulate these efflux pumps. Extending this knowledge, we demonstrated that guanidine itself can promote ionic liquid tolerance. Our findings will inform genetic engineering strategies that improve conversion of cellulosic sugars into biofuels and biochemicals in processes where low concentrations of ionic liquids surpass bacterial tolerance.
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38
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Trachman RJ, Autour A, Jeng SCY, Abdolahzadeh A, Andreoni A, Cojocaru R, Garipov R, Dolgosheina EV, Knutson JR, Ryckelynck M, Unrau PJ, Ferré-D'Amaré AR. Structure and functional reselection of the Mango-III fluorogenic RNA aptamer. Nat Chem Biol 2019; 15:472-479. [PMID: 30992561 DOI: 10.1038/s41589-019-0267-9] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/06/2019] [Indexed: 11/09/2022]
Abstract
Several turn-on RNA aptamers that activate small-molecule fluorophores have been selected in vitro. Among these, the ~30 nucleotide Mango-III is notable because it binds the thiazole orange derivative TO1-Biotin with high affinity and fluoresces brightly (quantum yield 0.55). Uniquely among related aptamers, Mango-III exhibits biphasic thermal melting, characteristic of molecules with tertiary structure. We report crystal structures of TO1-Biotin complexes of Mango-III, a structure-guided mutant Mango-III(A10U), and a functionally reselected mutant iMango-III. The structures reveal a globular architecture arising from an unprecedented pseudoknot-like connectivity between a G-quadruplex and an embedded non-canonical duplex. The fluorophore is restrained into a planar conformation by the G-quadruplex, a lone, long-range trans Watson-Crick pair (whose A10U mutation increases quantum yield to 0.66), and a pyrimidine perpendicular to the nucleobase planes of those motifs. The improved iMango-III and Mango-III(A10U) fluoresce ~50% brighter than enhanced green fluorescent protein, making them suitable tags for live cell RNA visualization.
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Affiliation(s)
- Robert J Trachman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Alexis Autour
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de biologie moléculaire et cellulaire du CNRS, Strasbourg, France
| | - Sunny C Y Jeng
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Amir Abdolahzadeh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Alessio Andreoni
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Razvan Cojocaru
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Ramil Garipov
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Elena V Dolgosheina
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jay R Knutson
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Michael Ryckelynck
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de biologie moléculaire et cellulaire du CNRS, Strasbourg, France
| | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA.
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Huang L, Wang J, Wilson TJ, Lilley DMJ. Structure-guided design of a high-affinity ligand for a riboswitch. RNA (NEW YORK, N.Y.) 2019; 25:423-430. [PMID: 30609994 PMCID: PMC6426286 DOI: 10.1261/rna.069567.118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
We have designed structure-based ligands for the guanidine-II riboswitch that bind with enhanced affinity, exploiting the twin binding sites created by loop-loop interaction. We synthesized diguanidine species, comprising two guanidino groups covalently connected by Cn linkers where n = 4 or 5. Calorimetric and fluorescent analysis shows that these ligands bind with a 10-fold higher affinity to the riboswitch compared to guanidine. We determined X-ray crystal structures of the riboswitch bound to the new ligands, showing that the guanidino groups are bound to both nucleobases and backbone within the binding pockets, analogously to guanidine binding. The connecting chain passes through side openings in the binding pocket and traverses the minor groove of the RNA. The combination of the riboswitch loop-loop interaction and our novel ligands has potential applications in chemical biology.
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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
| | - Timothy J Wilson
- 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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40
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Peselis A, Serganov A. ykkC riboswitches employ an add-on helix to adjust specificity for polyanionic ligands. Nat Chem Biol 2018; 14:887-894. [PMID: 30120360 PMCID: PMC6263941 DOI: 10.1038/s41589-018-0114-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/02/2018] [Indexed: 12/20/2022]
Abstract
The ykkC family of bacterial riboswitches combines several widespread classes that have similar secondary structures and consensus motifs but control different genes in response to different cellular metabolites. Here we report the crystal structures of two distinct ykkC riboswitches specifically bound to their cognate ligands ppGpp, a second messenger involved in stress response, or PRPP, a precursor in purine biosynthesis. Both RNAs adopt similar structures and contain a conserved core previously observed in the guanidine-specific ykkC riboswitch. However, ppGpp and PRPP riboswitches uniquely employ an additional helical element that joins the ends of the ligand-sensing domains and creates a tunnel for direct and Mg2+-mediated binding of ligands. Mutational and footprinting experiments highlight the importance of conserved nucleotides forming the tunnel and long-distance contacts for ligand binding and genetic response. Our work provides new insights into the specificity of riboswitches and gives a unique opportunity for future studies of RNA evolution.
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Affiliation(s)
- Alla Peselis
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Alexander Serganov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
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41
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Battaglia RA, Ke A. Guanidine-sensing riboswitches: How do they work and what do they regulate? WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1482. [DOI: 10.1002/wrna.1482] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/14/2018] [Accepted: 03/19/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Robert A. Battaglia
- Department of Molecular Biology and Genetics; Cornell University; Ithaca New York
| | - Ailong Ke
- Department of Molecular Biology and Genetics; Cornell University; Ithaca New York
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42
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Battaglia RA, Ke A. Acting in tandem. eLife 2018; 7:36489. [PMID: 29683426 PMCID: PMC5912904 DOI: 10.7554/elife.36489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 04/17/2018] [Indexed: 11/13/2022] Open
Abstract
RNA structures called tandem riboswitches allow bacteria to employ complex logical operations in response to nutrient starvation.
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Affiliation(s)
- Robert A Battaglia
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
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43
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Abstract
The small multidrug resistance (SMR) family of membrane proteins is prominent because of its rare dual topology architecture, simplicity, and small size. Its best studied member, EmrE, is an important model system in several fields related to membrane protein biology, from evolution to mechanism. But despite decades of work on these multidrug transporters, the native function of the SMR family has remained a mystery, and many highly similar SMR homologs do not transport drugs at all. Here we establish that representative SMR proteins, selected from each of the major clades in the phylogeny, function as guanidinium ion exporters. Drug-exporting SMRs are all clustered in a single minority clade. Using membrane transport experiments, we show that these guanidinium exporters, which we term Gdx, are very selective for guanidinium and strictly and stoichiometrically couple its export with the import of two protons. These findings draw important mechanistic distinctions with the notably promiscuous and weakly coupled drug exporters like EmrE.
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44
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Huang L, Wang J, Wilson TJ, Lilley DMJ. Structure of the Guanidine III Riboswitch. Cell Chem Biol 2017; 24:1407-1415.e2. [PMID: 28988949 PMCID: PMC5696562 DOI: 10.1016/j.chembiol.2017.08.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/20/2017] [Accepted: 08/29/2017] [Indexed: 01/09/2023]
Abstract
Riboswitches are structural elements found in mRNA molecules that couple small-molecule binding to regulation of gene expression, usually by controlling transcription or translation. We have determined high-resolution crystal structures of the ykkC guanidine III riboswitch from Thermobifida fusca. The riboswitch forms a classic H-type pseudoknot that includes a triple helix that is continuous with a central core of conserved nucleotides. These form a left-handed helical ramp of inter-nucleotide interactions, generating the guanidinium cation binding site. The ligand is hydrogen bonded to the Hoogsteen edges of two guanine bases. The binding pocket has a side opening that can accommodate a small side chain, shown by structures with bound methylguanidine, aminoguanidine, ethylguanidine, and agmatine. Comparison of the new structure with those of the guanidine I and II riboswitches reveals that evolution generated three different structural solutions for guanidine binding and subsequent gene regulation, although with some common elements.
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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
| | - Jia Wang
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Timothy J Wilson
- 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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