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Barth KM, Hiller DA, Strobel SA. The Impact of Second-Shell Nucleotides on Ligand Specificity in Cyclic Dinucleotide Riboswitches. Biochemistry 2024. [PMID: 38329042 DOI: 10.1021/acs.biochem.3c00586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Ligand specificity is an essential requirement for all riboswitches. Some variant riboswitches utilize a common structural motif, yet through subtle sequence differences, they are able to selectively respond to different small molecule ligands and regulate downstream gene expression. These variants discriminate between structurally and chemically similar ligands. Crystal structures provide insight into how specificity is achieved. However, ligand specificity cannot always be explained solely by nucleotides in direct contact with the ligand. The cyclic dinucleotide variant family contains two classes, cyclic-di-GMP and cyclic-AMP-GMP riboswitches, that were distinguished based on the identity of a single nucleotide in contact with the ligand. Here we report a variant riboswitch with a mutation at a second ligand-contacting position that is promiscuous for both cyclic-di-GMP and cyclic-AMP-GMP despite a predicted preference for cyclic-AMP-GMP. A high-throughput mutational analysis, SMARTT, was used to quantitatively assess thousands of sites in the first- and second-shells of ligand contact for impacts on ligand specificity and promiscuity. In addition to nucleotides in direct ligand contact, nucleotides more distal from the binding site, within the J1/2 linker and the terminator helix, were identified that impact ligand specificity. These findings provide an example of how nucleotides outside the ligand binding pocket influence the riboswitch specificity. Moreover, these distal nucleotides could be used to predict promiscuous sequences.
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Affiliation(s)
- Kathryn M Barth
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States
| | - David A Hiller
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States
| | - Scott A Strobel
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States
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2
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Troisi R, Balasco N, Autiero I, Vitagliano L, Sica F. Structural Insights into Protein-Aptamer Recognitions Emerged from Experimental and Computational Studies. Int J Mol Sci 2023; 24:16318. [PMID: 38003510 PMCID: PMC10671752 DOI: 10.3390/ijms242216318] [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: 10/20/2023] [Revised: 11/10/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Aptamers are synthetic nucleic acids that are developed to target with high affinity and specificity chemical entities ranging from single ions to macromolecules and present a wide range of chemical and physical properties. Their ability to selectively bind proteins has made these compounds very attractive and versatile tools, in both basic and applied sciences, to such an extent that they are considered an appealing alternative to antibodies. Here, by exhaustively surveying the content of the Protein Data Bank (PDB), we review the structural aspects of the protein-aptamer recognition process. As a result of three decades of structural studies, we identified 144 PDB entries containing atomic-level information on protein-aptamer complexes. Interestingly, we found a remarkable increase in the number of determined structures in the last two years as a consequence of the effective application of the cryo-electron microscopy technique to these systems. In the present paper, particular attention is devoted to the articulated architectures that protein-aptamer complexes may exhibit. Moreover, the molecular mechanism of the binding process was analyzed by collecting all available information on the structural transitions that aptamers undergo, from their protein-unbound to the protein-bound state. The contribution of computational approaches in this area is also highlighted.
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Affiliation(s)
- Romualdo Troisi
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy;
- Institute of Biostructures and Bioimaging, CNR, 80131 Naples, Italy;
| | - Nicole Balasco
- Institute of Molecular Biology and Pathology, CNR c/o Department of Chemistry, University of Rome Sapienza, 00185 Rome, Italy;
| | - Ida Autiero
- Institute of Biostructures and Bioimaging, CNR, 80131 Naples, Italy;
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging, CNR, 80131 Naples, Italy;
| | - Filomena Sica
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy;
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3
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Banna HA, Das NK, Ojha M, Koirala D. Advances in chaperone-assisted RNA crystallography using synthetic antibodies. BBA ADVANCES 2023; 4:100101. [PMID: 37655005 PMCID: PMC10466895 DOI: 10.1016/j.bbadva.2023.100101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/13/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023] Open
Abstract
RNA molecules play essential roles in many biological functions, from gene expression regulation, cellular growth, and metabolism to catalysis. They frequently fold into three-dimensional structures to perform their functions. Therefore, determining RNA structure represents a key step for understanding the structure-function relationships and developing RNA-targeted therapeutics. X-ray crystallography remains a method of choice for determining high-resolution RNA structures, but it has been challenging due to difficulties associated with RNA crystallization and phasing. Several natural and synthetic RNA binding proteins have been used to facilitate RNA crystallography. Having unique properties to help crystal packing and phasing, synthetic antibody fragments, specifically the Fabs, have emerged as promising RNA crystallization chaperones, and so far, over a dozen of RNA structures have been solved using this strategy. Nevertheless, multiple steps in this approach need to be improved, including the recombinant expression of these anti-RNA Fabs, to warrant the full potential of these synthetic Fabs as RNA crystallization chaperones. This review highlights the nuts and bolts and recent advances in the chaperone-assisted RNA crystallography approach, specifically emphasizing the Fab antibody fragments as RNA crystallization chaperones.
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Affiliation(s)
- Hasan Al Banna
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Naba Krishna Das
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Manju Ojha
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Deepak Koirala
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
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4
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Luo HT, He Q, Yang W, He F, Dong J, Hu CF, Yang XF, Li N, Li FR. Single-cell analyses reveal distinct expression patterns and roles of long non-coding RNAs during hESC differentiation into pancreatic progenitors. Stem Cell Res Ther 2023; 14:38. [PMID: 36907881 PMCID: PMC10010006 DOI: 10.1186/s13287-023-03259-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 02/22/2023] [Indexed: 03/14/2023] Open
Abstract
BACKGROUND Deep understanding the differentiation process of human embryonic stem cells (hESCs) is essential for developing cell-based therapeutic strategy. Substantial efforts have been made to investigate protein-coding genes, yet it remains lacking comprehensive characterization of long non-coding RNAs (lncRNAs) during this process. METHODS hESCs were passaged every 5-6 days and had maintained stable karyotype even until the 50th generation. Pancreatic progenitor specification of in vitro differentiation from hESCs was performed and modified. The nuclei were stained with 4,6-Diamidino-2-phenylindole (DAPI). Droplet-based platform (10X Genomics) was applied to generate the single-cell RNA sequencing (scRNA-seq) data. The quality of the filtered read pairs was evaluated by using FastQC. Batch effects were removed using the size factor method. Dimension reduction and unsupervised clustering analyses were performed using Seurat R package. The Monocle 2 and MetaCell algorithms were used to order single cells on a pseudotime course and partition the scRNA-seq data into metacells, respectively. Co-expression network was constructed using WGCNA. Module- and hub-based methods were adopted to predict the functions of lncRNAs. RESULTS A total of 77,382 cells during the differentiation process of hESCs toward pancreatic progenitors were sequenced. According to the single-cell map, the cells from different time points were authenticated to constitute a relatively homogeneous population, in which a total of 7382 lncRNAs could be detected. Through further analyzing the time course data, conserved and specific expression features of lncRNAs during hESC differentiation were revealed. Based upon pseudotime analysis, 52 pseudotime-associated lncRNAs that grouped into three distinct expression patterns were identified. We also implemented MetaCell algorithm and network-based methods to explore the functional mechanisms of these lncRNAs. Totally, 464 lncRNAs, including 49 pseudotime-associated lncRNAs were functionally annotated by either module-based or hub-based methods. Most importantly, we demonstrated that the lncRNA HOTAIRM1, which co-localized and co-expressed with several HOX genes, may play crucial role in the generation of pancreatic progenitors through regulation of exocytosis and retinoic acid receptor signaling pathway. CONCLUSIONS Our single-cell analyses provide valuable data resources for biological researchers and novel insights into hESC differentiation processes, which will guide future endeavors to further elucidate the roles of lncRNAs.
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Affiliation(s)
- Hai-Tao Luo
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China.,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China.,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China.,Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, 510632, China
| | - Qian He
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China.,School of Food and Drug, Shenzhen Polytechnic, Shenzhen, 518055, China.,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China.,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China.,Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, 510632, China
| | - Wei Yang
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China.,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China.,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Fei He
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China.,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China.,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jun Dong
- Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, 510632, China
| | - Chao-Feng Hu
- Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, 510632, China
| | - Xiao-Fei Yang
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China. .,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China. .,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Ning Li
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China. .,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China. .,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Fu-Rong Li
- Translational Medicine Collaborative Innovation Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, China. .,Guangdong Engineering Technology Research Center of Stem Cell and Cell Therapy, Shenzhen Key Laboratory of Stem Cell Research and Clinical Transformation, Shenzhen Immune Cell Therapy Public Service Platform, Shenzhen, 518020, China. .,Health Medicine Institute, Southern University of Science and Technology, Shenzhen, 518055, China. .,Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, 510632, China.
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5
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Kavita K, Breaker RR. Discovering riboswitches: the past and the future. Trends Biochem Sci 2023; 48:119-141. [PMID: 36150954 PMCID: PMC10043782 DOI: 10.1016/j.tibs.2022.08.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 08/18/2022] [Accepted: 08/26/2022] [Indexed: 01/25/2023]
Abstract
Riboswitches are structured noncoding RNA domains used by many bacteria to monitor the concentrations of target ligands and regulate gene expression accordingly. In the past 20 years over 55 distinct classes of natural riboswitches have been discovered that selectively sense small molecules or elemental ions, and thousands more are predicted to exist. Evidence suggests that some riboswitches might be direct descendants of the RNA-based sensors and switches that were likely present in ancient organisms before the evolutionary emergence of proteins. We provide an overview of the current state of riboswitch research, focusing primarily on the discovery of riboswitches, and speculate on the major challenges facing researchers in the field.
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Affiliation(s)
- Kumari Kavita
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8103, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103, USA.
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6
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Landgraf T, Völklein AE, Fürtig B, Schwalbe H. The cotranscriptional folding landscape for two cyclic di-nucleotide-sensing riboswitches with highly homologous aptamer domains acting either as ON- or OFF-switches. Nucleic Acids Res 2022; 50:6639-6655. [PMID: 35736222 PMCID: PMC9262584 DOI: 10.1093/nar/gkac514] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/03/2022] [Accepted: 06/07/2022] [Indexed: 12/24/2022] Open
Abstract
Riboswitches are gene regulatory elements located in untranslated mRNA regions. They bind inducer molecules with high affinity and specificity. Cyclic-di-nucleotide-sensing riboswitches are major regulators of genes for the environment, membranes and motility (GEMM) of bacteria. Up to now, structural probing assays or crystal structures have provided insight into the interaction between cyclic-di-nucleotides and their corresponding riboswitches. ITC analysis, NMR analysis and computational modeling allowed us to gain a detailed understanding of the gene regulation mechanisms for the Cd1 (Clostridium difficile) and for the pilM (Geobacter metallireducens) riboswitches and their respective di-nucleotides c-di-GMP and c-GAMP. Binding capability showed a 25 nucleotide (nt) long window for pilM and a 61 nt window for Cd1. Within this window, binding affinities ranged from 35 μM to 0.25 μM spanning two orders of magnitude for Cd1 and pilM showing a strong dependence on competing riboswitch folds. Experimental results were incorporated into a Markov simulation to further our understanding of the transcriptional folding pathways of riboswitches. Our model showed the ability to predict riboswitch gene regulation and its dependence on transcription speed, pausing and ligand concentration.
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Affiliation(s)
| | | | - Boris Fürtig
- Correspondence may also be addressed to Boris Fürtig.
| | - Harald Schwalbe
- To whom correspondence should be addressed. Tel: +49 69 798 29737; Fax: +49 69 798 29515;
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7
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The Signaling Pathway That cGAMP Riboswitches Found: Analysis and Application of Riboswitches to Study cGAMP Signaling in Geobacter sulfurreducens. Int J Mol Sci 2022; 23:ijms23031183. [PMID: 35163114 PMCID: PMC8835794 DOI: 10.3390/ijms23031183] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/12/2022] [Accepted: 01/14/2022] [Indexed: 02/03/2023] Open
Abstract
The Hypr cGAMP signaling pathway was discovered via the function of the riboswitch. In this study, we show the development of a method for affinity capture followed by sequencing to identify non-coding RNA regions that bind nucleotide signals such as cGAMP. The RNAseq of affinity-captured cGAMP riboswitches from the Geobacter sulfurreducens transcriptome highlights general challenges that remain for this technique. Furthermore, by applying riboswitch reporters in vivo, we identify new growth conditions and transposon mutations that affect cGAMP levels in G. sulfurreducens. This work reveals an extensive regulatory network and supports a second functional cGAMP synthase gene in G. sulfurreducens. The activity of the second synthase was validated using riboswitch-based fluorescent biosensors, and is the first known example of an active enzyme with a variant GGDDF motif.
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8
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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 2021; 23:e202100564. [PMID: 34847270 PMCID: PMC9300104 DOI: 10.1002/cbic.202100564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [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 Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7, 60438, Frankfurt/Main, Germany.,Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7-9, 60438, Frankfurt/Main, Germany
| | - Oliver Binas
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7, 60438, Frankfurt/Main, Germany.,Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7-9, 60438, Frankfurt/Main, Germany
| | - Andreas Schlundt
- Institute for Molecular Biosciences, Johann Wolfgang Goethe University, Max-von-Laue-Str. 9, 60438, Frankfurt/Main, Germany.,Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7-9, 60438, Frankfurt/Main, Germany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7, 60438, Frankfurt/Main, Germany.,Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7-9, 60438, Frankfurt/Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7, 60438, Frankfurt/Main, Germany.,Center for Biomolecular Magnetic Resonance, Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 7-9, 60438, Frankfurt/Main, Germany
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9
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Kang Y, Zhou Y, Li Y, Han Y, Xu J, Niu W, Li Z, Liu S, Feng H, Huang W, Duan R, Xu T, Raj N, Zhang F, Dou J, Xu C, Wu H, Bassell GJ, Warren ST, Allen EG, Jin P, Wen Z. A human forebrain organoid model of fragile X syndrome exhibits altered neurogenesis and highlights new treatment strategies. Nat Neurosci 2021; 24:1377-1391. [PMID: 34413513 PMCID: PMC8484073 DOI: 10.1038/s41593-021-00913-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 07/15/2021] [Indexed: 02/07/2023]
Abstract
Fragile X syndrome (FXS) is caused by the loss of fragile X mental retardation protein (FMRP), an RNA-binding protein that can regulate the translation of specific mRNAs. In this study, we developed an FXS human forebrain organoid model and observed that the loss of FMRP led to dysregulated neurogenesis, neuronal maturation and neuronal excitability. Bulk and single-cell gene expression analyses of FXS forebrain organoids revealed that the loss of FMRP altered gene expression in a cell-type-specific manner. The developmental deficits in FXS forebrain organoids could be rescued by inhibiting the phosphoinositide 3-kinase pathway but not the metabotropic glutamate pathway disrupted in the FXS mouse model. We identified a large number of human-specific mRNAs bound by FMRP. One of these human-specific FMRP targets, CHD2, contributed to the altered gene expression in FXS organoids. Collectively, our study revealed molecular, cellular and electrophysiological abnormalities associated with the loss of FMRP during human brain development.
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Affiliation(s)
- Yunhee Kang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA;,Department of Biostatistics and Bioinformatics, Emory University School of Public Health, Atlanta, GA 30322, USA
| | - Ying Zhou
- Department of Psychiatry and Behavioral Scieces, Emory University School of Medicine, Atlanta, GA 30322, USA;,Department of Biostatistics and Bioinformatics, Emory University School of Public Health, Atlanta, GA 30322, USA
| | - Yujing Li
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA;,Department of Biostatistics and Bioinformatics, Emory University School of Public Health, Atlanta, GA 30322, USA
| | - Yanfei Han
- Department of Psychiatry and Behavioral Scieces, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jie Xu
- The Graduate Program in Genetics and Molecular Biology, Emory University, GA 30322, USA
| | - Weibo Niu
- Department of Psychiatry and Behavioral Scieces, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ziyi Li
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Shiying Liu
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, OH 44106, USA
| | - Hao Feng
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, OH 44106, USA
| | - Wen Huang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Ranhui Duan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Tianmin Xu
- Department of Gynecology and Obstetrics, The Second Hospital of Jilin University, Changchun, Jilin, China
| | - Nisha Raj
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Feiran Zhang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Juan Dou
- Department of Psychiatry and Behavioral Scieces, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Chongchong Xu
- Department of Psychiatry and Behavioral Scieces, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Hao Wu
- Department of Biostatistics and Bioinformatics, Emory University School of Public Health, Atlanta, GA 30322, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Stephen T Warren
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Emily G Allen
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA;,To whom correspondence should be addressed: (P.J.) and (Z.W.)
| | - Zhexing Wen
- Department of Psychiatry and Behavioral Scieces, Emory University School of Medicine, Atlanta, GA 30322, USA;,Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA;,To whom correspondence should be addressed: (P.J.) and (Z.W.)
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10
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Kitto RZ, Christiansen KE, Hammond MC. RNA-based fluorescent biosensors for live cell detection of bacterial sRNA. Biopolymers 2021; 112:e23394. [PMID: 32786000 PMCID: PMC7856060 DOI: 10.1002/bip.23394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/11/2020] [Accepted: 07/13/2020] [Indexed: 01/21/2023]
Abstract
Bacteria contain a diverse set of RNAs to provide tight regulation of gene expression in response to environmental stimuli. Bacterial small RNAs (sRNAs) work in conjunction with protein cofactors to bind complementary mRNA sequences in the cell, leading to up- or downregulation of protein synthesis. In vivo imaging of sRNAs can aid in understanding their spatiotemporal dynamics in real time, which inspires new ways to manipulate these systems for a variety of applications including synthetic biology and therapeutics. Current methods for sRNA imaging are quite limited in vivo and do not provide real-time information about fluctuations in sRNA levels. Herein, we describe our efforts toward the development of an RNA-based fluorescent biosensor for bacterial sRNA both in vitro and in vivo. We validated these sensors for three different bacterial sRNAs in Escherichia coli and demonstrated that the designs provide a bright, sequence-specific signal output in response to exogenous and endogenous RNA targets.
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Affiliation(s)
- Rebekah Z Kitto
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Kylee E Christiansen
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, USA
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11
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Yu AM, Choi YH, Tu MJ. RNA Drugs and RNA Targets for Small Molecules: Principles, Progress, and Challenges. Pharmacol Rev 2020; 72:862-898. [PMID: 32929000 PMCID: PMC7495341 DOI: 10.1124/pr.120.019554] [Citation(s) in RCA: 184] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
RNA-based therapies, including RNA molecules as drugs and RNA-targeted small molecules, offer unique opportunities to expand the range of therapeutic targets. Various forms of RNAs may be used to selectively act on proteins, transcripts, and genes that cannot be targeted by conventional small molecules or proteins. Although development of RNA drugs faces unparalleled challenges, many strategies have been developed to improve RNA metabolic stability and intracellular delivery. A number of RNA drugs have been approved for medical use, including aptamers (e.g., pegaptanib) that mechanistically act on protein target and small interfering RNAs (e.g., patisiran and givosiran) and antisense oligonucleotides (e.g., inotersen and golodirsen) that directly interfere with RNA targets. Furthermore, guide RNAs are essential components of novel gene editing modalities, and mRNA therapeutics are under development for protein replacement therapy or vaccination, including those against unprecedented severe acute respiratory syndrome coronavirus pandemic. Moreover, functional RNAs or RNA motifs are highly structured to form binding pockets or clefts that are accessible by small molecules. Many natural, semisynthetic, or synthetic antibiotics (e.g., aminoglycosides, tetracyclines, macrolides, oxazolidinones, and phenicols) can directly bind to ribosomal RNAs to achieve the inhibition of bacterial infections. Therefore, there is growing interest in developing RNA-targeted small-molecule drugs amenable to oral administration, and some (e.g., risdiplam and branaplam) have entered clinical trials. Here, we review the pharmacology of novel RNA drugs and RNA-targeted small-molecule medications, with a focus on recent progresses and strategies. Challenges in the development of novel druggable RNA entities and identification of viable RNA targets and selective small-molecule binders are discussed. SIGNIFICANCE STATEMENT: With the understanding of RNA functions and critical roles in diseases, as well as the development of RNA-related technologies, there is growing interest in developing novel RNA-based therapeutics. This comprehensive review presents pharmacology of both RNA drugs and RNA-targeted small-molecule medications, focusing on novel mechanisms of action, the most recent progress, and existing challenges.
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MESH Headings
- Aptamers, Nucleotide/pharmacology
- Aptamers, Nucleotide/therapeutic use
- Betacoronavirus
- COVID-19
- Chemistry Techniques, Analytical/methods
- Chemistry Techniques, Analytical/standards
- Clustered Regularly Interspaced Short Palindromic Repeats
- Coronavirus Infections/drug therapy
- Drug Delivery Systems/methods
- Drug Development/organization & administration
- Drug Discovery
- Humans
- MicroRNAs/pharmacology
- MicroRNAs/therapeutic use
- Oligonucleotides, Antisense/pharmacology
- Oligonucleotides, Antisense/therapeutic use
- Pandemics
- Pneumonia, Viral/drug therapy
- RNA/adverse effects
- RNA/drug effects
- RNA/pharmacology
- RNA, Antisense/pharmacology
- RNA, Antisense/therapeutic use
- RNA, Messenger/drug effects
- RNA, Messenger/pharmacology
- RNA, Ribosomal/drug effects
- RNA, Ribosomal/pharmacology
- RNA, Small Interfering/pharmacology
- RNA, Small Interfering/therapeutic use
- RNA, Viral/drug effects
- Ribonucleases/metabolism
- Riboswitch/drug effects
- SARS-CoV-2
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Affiliation(s)
- Ai-Ming Yu
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California (A.-M.Y., Y.H.C., M.-J.T.) and College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyonggi-do, Republic of Korea (Y.H.C.)
| | - Young Hee Choi
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California (A.-M.Y., Y.H.C., M.-J.T.) and College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyonggi-do, Republic of Korea (Y.H.C.)
| | - Mei-Juan Tu
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California (A.-M.Y., Y.H.C., M.-J.T.) and College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyonggi-do, Republic of Korea (Y.H.C.)
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12
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Binas O, de Jesus V, Landgraf T, Völklein AE, Martins J, Hymon D, Kaur Bains J, Berg H, Biedenbänder T, Fürtig B, Lakshmi Gande S, Niesteruk A, Oxenfarth A, Shahin Qureshi N, Schamber T, Schnieders R, Tröster A, Wacker A, Wirmer-Bartoschek J, Wirtz Martin MA, Stirnal E, Azzaoui K, Richter C, Sreeramulu S, José Blommers MJ, Schwalbe H. 19 F NMR-Based Fragment Screening for 14 Different Biologically Active RNAs and 10 DNA and Protein Counter-Screens. Chembiochem 2020; 22:423-433. [PMID: 32794266 PMCID: PMC7436455 DOI: 10.1002/cbic.202000476] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/11/2020] [Indexed: 11/17/2022]
Abstract
We report here the nuclear magnetic resonance 19F screening of 14 RNA targets with different secondary and tertiary structure to systematically assess the druggability of RNAs. Our RNA targets include representative bacterial riboswitches that naturally bind with nanomolar affinity and high specificity to cellular metabolites of low molecular weight. Based on counter‐screens against five DNAs and five proteins, we can show that RNA can be specifically targeted. To demonstrate the quality of the initial fragment library that has been designed for easy follow‐up chemistry, we further show how to increase binding affinity from an initial fragment hit by chemistry that links the identified fragment to the intercalator acridine. Thus, we achieve low‐micromolar binding affinity without losing binding specificity between two different terminator structures.
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Affiliation(s)
- Oliver Binas
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Vanessa de Jesus
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Tom Landgraf
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Albrecht Eduard Völklein
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Jason Martins
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Daniel Hymon
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Jasleen Kaur Bains
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Hannes Berg
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Thomas Biedenbänder
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Boris Fürtig
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Santosh Lakshmi Gande
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Anna Niesteruk
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Andreas Oxenfarth
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Nusrat Shahin Qureshi
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Tatjana Schamber
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Robbin Schnieders
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Alix Tröster
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Julia Wirmer-Bartoschek
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Maria Alexandra Wirtz Martin
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Elke Stirnal
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Kamal Azzaoui
- Saverna Therapeutics, Gewerbestrasse 24, 4123, Allschwil, Switzerland
| | - Christian Richter
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | - Sridhar Sreeramulu
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
| | | | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue Strasse 7, 60438, Frankfurt am Main, Germany
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13
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Aline Dias da P, Nathalia Marins de A, Gabriel Guarany de A, Robson Francisco de S, Cristiane Rodrigues G. The World of Cyclic Dinucleotides in Bacterial Behavior. Molecules 2020; 25:molecules25102462. [PMID: 32466317 PMCID: PMC7288161 DOI: 10.3390/molecules25102462] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 02/07/2023] Open
Abstract
The regulation of multiple bacterial phenotypes was found to depend on different cyclic dinucleotides (CDNs) that constitute intracellular signaling second messenger systems. Most notably, c-di-GMP, along with proteins related to its synthesis, sensing, and degradation, was identified as playing a central role in the switching from biofilm to planktonic modes of growth. Recently, this research topic has been under expansion, with the discoveries of new CDNs, novel classes of CDN receptors, and the numerous functions regulated by these molecules. In this review, we comprehensively describe the three main bacterial enzymes involved in the synthesis of c-di-GMP, c-di-AMP, and cGAMP focusing on description of their three-dimensional structures and their structural similarities with other protein families, as well as the essential residues for catalysis. The diversity of CDN receptors is described in detail along with the residues important for the interaction with the ligand. Interestingly, genomic data strongly suggest that there is a tendency for bacterial cells to use both c-di-AMP and c-di-GMP signaling networks simultaneously, raising the question of whether there is crosstalk between different signaling systems. In summary, the large amount of sequence and structural data available allows a broad view of the complexity and the importance of these CDNs in the regulation of different bacterial behaviors. Nevertheless, how cells coordinate the different CDN signaling networks to ensure adaptation to changing environmental conditions is still open for much further exploration.
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14
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He J, Yin W, Galperin MY, Chou SH. Cyclic di-AMP, a second messenger of primary importance: tertiary structures and binding mechanisms. Nucleic Acids Res 2020; 48:2807-2829. [PMID: 32095817 DOI: 10.1093/nar/gkaa112] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/09/2020] [Accepted: 02/21/2020] [Indexed: 12/12/2022] Open
Abstract
Cyclic diadenylate (c-di-AMP) is a widespread second messenger in bacteria and archaea that is involved in the maintenance of osmotic pressure, response to DNA damage, and control of central metabolism, biofilm formation, acid stress resistance, and other functions. The primary importance of c-di AMP stems from its essentiality for many bacteria under standard growth conditions and the ability of several eukaryotic proteins to sense its presence in the cell cytoplasm and trigger an immune response by the host cells. We review here the tertiary structures of the domains that regulate c-di-AMP synthesis and signaling, and the mechanisms of c-di-AMP binding, including the principal conformations of c-di-AMP, observed in various crystal structures. We discuss how these c-di-AMP molecules are bound to the protein and riboswitch receptors and what kinds of interactions account for the specific high-affinity binding of the c-di-AMP ligand. We describe seven kinds of non-covalent-π interactions between c-di-AMP and its receptor proteins, including π-π, C-H-π, cation-π, polar-π, hydrophobic-π, anion-π and the lone pair-π interactions. We also compare the mechanisms of c-di-AMP and c-di-GMP binding by the respective receptors that allow these two cyclic dinucleotides to control very different biological functions.
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Affiliation(s)
- Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China.,Institute of Biochemistry and Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
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15
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He J, Yin W, Galperin MY, Chou SH. Cyclic di-AMP, a second messenger of primary importance: tertiary structures and binding mechanisms. Nucleic Acids Res 2020. [PMID: 32095817 DOI: 10.1093/nar/gkaa112"] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cyclic diadenylate (c-di-AMP) is a widespread second messenger in bacteria and archaea that is involved in the maintenance of osmotic pressure, response to DNA damage, and control of central metabolism, biofilm formation, acid stress resistance, and other functions. The primary importance of c-di AMP stems from its essentiality for many bacteria under standard growth conditions and the ability of several eukaryotic proteins to sense its presence in the cell cytoplasm and trigger an immune response by the host cells. We review here the tertiary structures of the domains that regulate c-di-AMP synthesis and signaling, and the mechanisms of c-di-AMP binding, including the principal conformations of c-di-AMP, observed in various crystal structures. We discuss how these c-di-AMP molecules are bound to the protein and riboswitch receptors and what kinds of interactions account for the specific high-affinity binding of the c-di-AMP ligand. We describe seven kinds of non-covalent-π interactions between c-di-AMP and its receptor proteins, including π-π, C-H-π, cation-π, polar-π, hydrophobic-π, anion-π and the lone pair-π interactions. We also compare the mechanisms of c-di-AMP and c-di-GMP binding by the respective receptors that allow these two cyclic dinucleotides to control very different biological functions.
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Affiliation(s)
- Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China.,Institute of Biochemistry and Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
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16
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Knappenberger AJ, Reiss CW, Focht CM, Strobel SA. A Modular RNA Domain That Confers Differential Ligand Specificity. Biochemistry 2020; 59:1361-1366. [PMID: 32202416 DOI: 10.1021/acs.biochem.0c00117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The modularity of protein domains is well-known, but the existence of independent domains that confer function in RNA is less established. Recently, a family of RNA aptamers termed ykkC was discovered; they bind at least four ligands of very different chemical composition, including guanidine, phosphoribosyl pyrophosphate (PRPP), and guanosine tetraphosphate (ppGpp) (graphical abstract). Structures of these aptamers revealed an architecture characterized by two coaxial helical stacks. The first helix appears to be a generic scaffold, while the second helix forms the most contacts to the ligands. To determine if these two regions within the aptamer are modular units for ligand recognition, we swapped the ligand-binding coaxial stacks of a guanidine aptamer and a PRPP aptamer. This operation, in combination with a single mutation in the scaffold domain, achieved full switching of ligand specificity. This finding suggests that the ligand-binding helix largely dictates the ligand specificity of ykkC RNAs and that the scaffold coaxial stack is generally compatible with various ykkC ligand-binding modules. This work presents an example of RNA domain modularity comparable to that of a ligand-binding protein, showcasing the versatility of RNA as an entity capable of molecular evolution through adaptation of existing motifs.
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Affiliation(s)
- Andrew J Knappenberger
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States.,Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
| | - Caroline W Reiss
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States.,Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
| | - Caroline M Focht
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States.,Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
| | - Scott A Strobel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States.,Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States.,Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
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17
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RNA-based fluorescent biosensors for live cell imaging of small molecules and RNAs. Curr Opin Biotechnol 2020; 63:157-166. [PMID: 32086101 DOI: 10.1016/j.copbio.2020.01.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/23/2019] [Accepted: 01/03/2020] [Indexed: 12/23/2022]
Abstract
Genetically encodable fluorescent biosensors provide spatiotemporal information on their target analytes in a label-free manner, which has enabled the study of cell biology and signaling in living cells. Over the past three decades, fueled by the development of a wide palette of fluorescent proteins, protein-based fluorescent biosensors against a broad array of targets have been developed. Recently, with the development of fluorogenic RNA aptamer-dye pairs that function in live cells, RNA-based fluorescent (RBF) biosensors have emerged as a complementary class of biosensors. Here we review the current state-of-the-art for fluorogenic RNA aptamers and RBF biosensors for imaging small molecules and RNAs, and highlight some emerging opportunities.
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18
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Soyal SM, Bonova P, Kwik M, Zara G, Auer S, Scharler C, Strunk D, Nofziger C, Paulmichl M, Patsch W. The Expression of CNS-Specific PPARGC1A Transcripts Is Regulated by Hypoxia and a Variable GT Repeat Polymorphism. Mol Neurobiol 2020; 57:752-764. [PMID: 31471878 PMCID: PMC7031416 DOI: 10.1007/s12035-019-01731-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 08/01/2019] [Indexed: 12/12/2022]
Abstract
PPARGC1A encodes a transcriptional co-activator also termed peroxisome proliferator-activated receptor (PPAR) gamma coactivator 1-alpha (PGC-1α) which orchestrates multiple transcriptional programs. We have recently identified CNS-specific transcripts that are initiated far upstream of the reference gene (RG) promoter. The regulation of these isoforms may be relevant, as experimental and genetic studies implicated the PPARGC1A locus in neurodegenerative diseases. We therefore studied cis- and trans-regulatory elements activating the CNS promoter in comparison to the RG promoter in human neuronal cell lines. A naturally occurring variable guanidine thymidine (GT) repeat polymorphism within a microsatellite region in the proximal CNS promoter increases promoter activity in neuronal cell lines. Both the RG and the CNS promoters are activated by ESRRA, and the PGC-1α isoforms co-activate ESRRA on their own promoters suggesting an autoregulatory feedback loop. The proximal CNS, but not the RG, promoter is induced by FOXA2 and co-activated by PGC-1α resulting in robust activation. Furthermore, the CNS, but not the RG, promoter is targeted by the canonical hypoxia response involving HIF1A. Importantly, the transactivation by HIF1A is modulated by the size of the GT polymorphism. Increased expression of CNS-specific transcripts in response to hypoxia was observed in an established rat model, while RG transcripts encoding the full-length reference protein were not increased. These results suggest a role of the CNS region of the PPARGC1A locus in ischemia and warrant further studies in humans as the activity of the CNS promoter as well as its induction by hypoxia is subject to inter-individual variability due to the GT polymorphism.
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Affiliation(s)
- Selma M Soyal
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020, Salzburg, Austria.
| | - Petra Bonova
- Institute of Neurobiology, Biomedical Research Center of the Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Markus Kwik
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020, Salzburg, Austria
| | - Greta Zara
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020, Salzburg, Austria
| | - Simon Auer
- Institute for Medical and Chemical Laboratory Diagnostics, Paracelsus Medical University, 5020, Salzburg, Austria
| | - Cornelia Scharler
- Institute of Experimental and Clinical Cell Therapy, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, 5020, Salzburg, Austria
| | - Dirk Strunk
- Institute of Experimental and Clinical Cell Therapy, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, 5020, Salzburg, Austria
| | | | - Markus Paulmichl
- PharmGenetix GmbH, Niederalm, 5081, Salzburg, Austria
- Department of Personalized Medicine, Humanomed, 9020, Klagenfurt, Austria
| | - Wolfgang Patsch
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020, Salzburg, Austria.
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19
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Winnerdy FR, Das P, Heddi B, Phan AT. Solution Structures of a G-Quadruplex Bound to Linear- and Cyclic-Dinucleotides. J Am Chem Soc 2019; 141:18038-18047. [PMID: 31661272 DOI: 10.1021/jacs.9b05642] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cyclic dinucleotides have emerged as important secondary messengers and cell signaling molecules that regulate several cell responses. A guanine-deficit G-quadruplex structure formation by a sequence containing (4n - 1) guanines, n denoting the number of G-tetrad layers, was previously reported. Here, a (4n - 1) G-quadruplex structure is shown to be capable of binding guanine-containing dinucleotides in micromolar affinity. The guanine base of the dinucleotides interacts with a vacant G-triad, forming four additional Hoogsteen hydrogen bonds to complete a G-tetrad. Solution structures of two complexes, both comprised of a (4n - 1) G-quadruplex structure, one bound to a linear dinucleotide (d(AG)) and the other to a cyclic dinucleotide (cGAMP), are solved using NMR spectroscopy. The latter suggests sufficiently strong interaction between the guanine base of the dinucleotide and the vacant G-triad, which acts as an anchor point of binding. The binding interfaces from the two solution structures provide useful information for specific ligand design. The results also infer that other guanine-containing metabolites of a similar size have the capability of binding G-quadruplexes, potentially affecting the expression of the metabolites and functionality of the bound G-quadruplexes.
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Affiliation(s)
- Fernaldo Richtia Winnerdy
- School of Physical and Mathematical Sciences , Nanyang Technological University , Singapore 637371 , Singapore
| | - Poulomi Das
- School of Physical and Mathematical Sciences , Nanyang Technological University , Singapore 637371 , Singapore
| | - Brahim Heddi
- School of Physical and Mathematical Sciences , Nanyang Technological University , Singapore 637371 , Singapore.,Laboratoire de Biologie et de Pharmacologie Appliquée , CNRS UMR 8113 , Ecole Normale Supérieure Paris-Saclay , Cachan 94235 , France
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences , Nanyang Technological University , Singapore 637371 , Singapore.,NTU Institute of Structural Biology , Nanyang Technological University , Singapore 636921 , Singapore
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20
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The Vc2 Cyclic di-GMP-Dependent Riboswitch of Vibrio cholerae Regulates Expression of an Upstream Putative Small RNA by Controlling RNA Stability. J Bacteriol 2019; 201:JB.00293-19. [PMID: 31405916 DOI: 10.1128/jb.00293-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/17/2019] [Indexed: 11/20/2022] Open
Abstract
Cyclic di-GMP (c-di-GMP) is a bacterial second messenger molecule that is important in the biology of Vibrio cholerae, but the molecular mechanisms by which this molecule regulates downstream phenotypes have not been fully characterized. We have previously shown that the Vc2 c-di-GMP-binding riboswitch, encoded upstream of the gene tfoY, functions as an off switch in response to c-di-GMP. However, the mechanism by which c-di-GMP controls expression of tfoY has not been fully elucidated. During our studies of this mechanism, we determined that c-di-GMP binding to Vc2 also controls the abundance and stability of upstream noncoding RNAs with 3' ends located immediately downstream of the Vc2 riboswitch. Our results suggest these putative small RNAs (sRNAs) are not generated by transcriptional termination but rather by preventing degradation of the upstream untranslated RNA when c-di-GMP is bound to Vc2.IMPORTANCE Riboswitches are typically RNA elements located in the 5' untranslated region of mRNAs. They are highly structured and specifically recognize and respond to a given chemical cue to alter transcription termination or translation initiation. In this work, we report a novel mechanism of riboswitch-mediated gene regulation in Vibrio cholerae whereby a 3' riboswitch, named Vc2, controls the stability of upstream untranslated RNA upon binding to its cognate ligand, the second messenger cyclic di-GMP, leading to the accumulation of previously undescribed putative sRNAs. We further demonstrate that binding of the ligand to the riboswitch prevents RNA degradation. As binding of riboswitches to their ligands often produces compactly structured RNA, we hypothesize this mechanism of gene regulation is widespread.
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Launer-Felty KD, Strobel SA. Enzymatic synthesis of cyclic dinucleotide analogs by a promiscuous cyclic-AMP-GMP synthetase and analysis of cyclic dinucleotide responsive riboswitches. Nucleic Acids Res 2019. [PMID: 29514227 PMCID: PMC5888326 DOI: 10.1093/nar/gky137] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cyclic dinucleotides are second messenger molecules produced by both prokaryotes and eukaryotes in response to external stimuli. In bacteria, these molecules bind to RNA riboswitches and several protein receptors ultimately leading to phenotypic changes such as biofilm formation, ion transport and secretion of virulence factors. Some cyclic dinucleotide analogs bind differentially to biological receptors and can therefore be used to better understand cyclic dinucleotide mechanisms in vitro and in vivo. However, production of some of these analogs involves lengthy, multistep syntheses. Here, we describe a new, simple method for enzymatic synthesis of several 3′, 5′ linked cyclic dinucleotide analogs of c-di-GMP, c-di-AMP and c-AMP-GMP using the cyclic-AMP-GMP synthetase, DncV. The enzymatic reaction efficiently produced most cyclic dinucleotide analogs, such as 2′-amino sugar substitutions and phosphorothioate backbone modifications, for all three types of cyclic dinucleotides without the use of protecting groups or organic solvents. We used these novel analogs to explore differences in phosphate backbone and 2′-hydroxyl recognition between GEMM-I and GEMM-Ib riboswitches.
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Affiliation(s)
- Katherine D Launer-Felty
- Department of Molecular Biophysics and Biochemistry and Department of Chemistry, Chemical Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Scott A Strobel
- Department of Molecular Biophysics and Biochemistry and Department of Chemistry, Chemical Biology Institute, Yale University, West Haven, CT 06516, USA
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22
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Abstract
RNA is a versatile biomolecule capable of transferring information, taking on distinct three-dimensional shapes, and reacting to ambient conditions. RNA molecules utilize a wide range of mechanisms to control gene expression. An example of such regulation is riboswitches. Consisting exclusively of RNA, they are able to control important metabolic processes, thus providing an elegant and efficient RNA-only regulation system. Existing across all domains of life, riboswitches appear to represent one of the most highly conserved mechanisms for the regulation of a broad range of biochemical pathways. Through binding of a wide range of small-molecule ligands to their so-called aptamer domain, riboswitches undergo a conformational change in their downstream "expression platform." In consequence, the pattern of gene expression changes, which in turn results in increased or decreased protein production. Riboswitches unite the sensing and transduction of a signal that can directly be coupled to the metabolism of the cell; thus they constitute a very potent regulatory mechanism for many organisms. Highly specific RNA-binding domains not only occur in vivo but can also be evolved by means of the SELEX (systematic evolution of ligands by exponential enrichment) method, which allows in vitro selection of aptamers against almost any ligand. Coupling of these aptamers with an expression platform has led to the development of synthetic riboswitches, a highly active research field of great relevance and immense potential. The aim of this review is to summarize developments in the riboswitch field over the last decade and address key questions of recent research.
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23
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Li C, Zhao X, Zhu X, Xie P, Chen G. Structural Studies of the 3',3'-cGAMP Riboswitch Induced by Cognate and Noncognate Ligands Using Molecular Dynamics Simulation. Int J Mol Sci 2018; 19:ijms19113527. [PMID: 30423927 PMCID: PMC6274999 DOI: 10.3390/ijms19113527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/03/2018] [Accepted: 11/04/2018] [Indexed: 01/09/2023] Open
Abstract
Riboswtich RNAs can control gene expression through the structural change induced by the corresponding small-molecule ligands. Molecular dynamics simulations and free energy calculations on the aptamer domain of the 3′,3′-cGAMP riboswitch in the ligand-free, cognate-bound and noncognate-bound states were performed to investigate the structural features of the 3′,3′-cGAMP riboswitch induced by the 3′,3′-cGAMP ligand and the specificity of ligand recognition. The results revealed that the aptamer of the 3′,3′-cGAMP riboswitch in the ligand-free state has a smaller binding pocket and a relatively compact structure versus that in the 3′,3′-cGAMP-bound state. The binding of the 3′,3′-cGAMP molecule to the 3′,3′-cGAMP riboswitch induces the rotation of P1 helix through the allosteric communication from the binding sites pocket containing the J1/2, J1/3 and J2/3 junction to the P1 helix. Simultaneously, these simulations also revealed that the preferential binding of the 3′,3′-cGAMP riboswitch to its cognate ligand, 3′,3′-cGAMP, over its noncognate ligand, c-di-GMP and c-di-AMP. The J1/2 junction in the 3′,3′-cGAMP riboswitch contributing to the specificity of ligand recognition have also been found.
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Affiliation(s)
- Chaoqun Li
- College of Chemistry, Chemical Engineering and Materials, Handan University, No. 530 North Xueyuan Road, Hanshan District, Han Dan 056005, Hebei, China.
| | - Xiaojia Zhao
- College of Chemistry, Chemical Engineering and Materials, Handan University, No. 530 North Xueyuan Road, Hanshan District, Han Dan 056005, Hebei, China.
| | - Xiaomin Zhu
- College of Chemistry, Chemical Engineering and Materials, Handan University, No. 530 North Xueyuan Road, Hanshan District, Han Dan 056005, Hebei, China.
| | - Pengtao Xie
- College of Chemistry, Chemical Engineering and Materials, Handan University, No. 530 North Xueyuan Road, Hanshan District, Han Dan 056005, Hebei, China.
| | - Guangju Chen
- College of Chemistry, Beijing Normal University, 19# Xinjiekouwai Street, Beijing 100875, China.
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Keller H, Weickhmann AK, Bock T, Wöhnert J. Adenine protonation enables cyclic-di-GMP binding to cyclic-GAMP sensing riboswitches. RNA (NEW YORK, N.Y.) 2018; 24:1390-1402. [PMID: 30006500 PMCID: PMC6140456 DOI: 10.1261/rna.067470.118] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 07/09/2018] [Indexed: 05/22/2023]
Abstract
In certain structural or functional contexts, RNA structures can contain protonated nucleotides. However, a direct role for stably protonated nucleotides in ligand binding and ligand recognition has not yet been demonstrated unambiguously. Previous X-ray structures of c-GAMP binding riboswitch aptamer domains in complex with their near-cognate ligand c-di-GMP suggest that an adenine of the riboswitch either forms two hydrogen bonds to a G nucleotide of the ligand in the unusual enol tautomeric form or that the adenine in its N1 protonated form binds the G nucleotide of the ligand in its canonical keto tautomeric state. By using NMR spectroscopy we demonstrate that the c-GAMP riboswitches bind c-di-GMP using a stably protonated adenine in the ligand binding pocket. Thereby, we provide novel insights into the putative biological functions of protonated nucleotides in RNA, which in this case influence the ligand selectivity in a riboswitch.
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Affiliation(s)
- Heiko Keller
- Institute for Molecular Biosciences and Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - A Katharina Weickhmann
- Institute for Molecular Biosciences and Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Thomas Bock
- Institute for Molecular Biosciences and Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Jens Wöhnert
- Institute for Molecular Biosciences and Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
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25
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Browne JA, Leir SH, Eggener SE, Harris A. Region-specific innate antiviral responses of the human epididymis. Mol Cell Endocrinol 2018; 473:72-78. [PMID: 29339104 PMCID: PMC6045438 DOI: 10.1016/j.mce.2018.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 01/08/2018] [Accepted: 01/08/2018] [Indexed: 12/27/2022]
Abstract
Viral infections of the epididymis are associated with epididymitis, which damages the epithelium and impairs fertility. We showed previously that innate immune response genes were differentially expressed in the corpus and cauda region of the human epididymis in comparison to the caput. Here we investigate the antiviral defense response mechanisms of human epididymis epithelial (HEE) cells. Toll-like receptor (TLR) 3 and retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are enriched in HEE cells from the corpus and cauda region. These HEE cells show an enhanced response to antiviral ligands (poly(I:C) and HSV-60), as shown by increased IFN-β mRNA expression and IFN-β secretion. Nuclear translocation of phosphorylated p65 occurs after poly(I:C) exposure. In addition, paired box 2 (PAX2), which was implicated in regulating antiviral response pathways, is required for basal expression of the DNA sensor, Z-DNA binding protein (ZBP1) and type I interferon, in caput but not in cauda cells.
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Affiliation(s)
- James A Browne
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Shih-Hsing Leir
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Scott E Eggener
- Section of Urology, University of Chicago Medical Center, Chicago, IL, 60637, USA
| | - Ann Harris
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.
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26
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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: 4.5] [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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27
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Belashov IA, Crawford DW, Cavender CE, Dai P, Beardslee PC, Mathews DH, Pentelute BL, McNaughton BR, Wedekind JE. Structure of HIV TAR in complex with a Lab-Evolved RRM provides insight into duplex RNA recognition and synthesis of a constrained peptide that impairs transcription. Nucleic Acids Res 2018; 46:6401-6415. [PMID: 29961805 PMCID: PMC6061845 DOI: 10.1093/nar/gky529] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/23/2018] [Accepted: 05/25/2018] [Indexed: 12/22/2022] Open
Abstract
Natural and lab-evolved proteins often recognize their RNA partners with exquisite affinity. Structural analysis of such complexes can offer valuable insight into sequence-selective recognition that can be exploited to alter biological function. Here, we describe the structure of a lab-evolved RNA recognition motif (RRM) bound to the HIV-1 trans-activation response (TAR) RNA element at 1.80 Å-resolution. The complex reveals a trio of arginines in an evolved β2-β3 loop penetrating deeply into the major groove to read conserved guanines while simultaneously forming cation-π and salt-bridge contacts. The observation that the evolved RRM engages TAR within a double-stranded stem is atypical compared to most RRMs. Mutagenesis, thermodynamic analysis and molecular dynamics validate the atypical binding mode and quantify molecular contributions that support the exceptionally tight binding of the TAR-protein complex (KD,App of 2.5 ± 0.1 nM). These findings led to the hypothesis that the β2-β3 loop can function as a standalone TAR-recognition module. Indeed, short constrained peptides comprising the β2-β3 loop still bind TAR (KD,App of 1.8 ± 0.5 μM) and significantly weaken TAR-dependent transcription. Our results provide a detailed understanding of TAR molecular recognition and reveal that a lab-evolved protein can be reduced to a minimal RNA-binding peptide.
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Affiliation(s)
- Ivan A Belashov
- Department of Biochemistry & Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - David W Crawford
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | - Chapin E Cavender
- Department of Biochemistry & Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Peng Dai
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Patrick C Beardslee
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Koch Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Broad Institute of Harvard and MIT, Cambridge, MA 02139, USA
| | - Brian R McNaughton
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Joseph E Wedekind
- Department of Biochemistry & Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
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28
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Direct activation of a phospholipase by cyclic GMP-AMP in El Tor Vibrio cholerae. Proc Natl Acad Sci U S A 2018; 115:E6048-E6055. [PMID: 29891656 PMCID: PMC6042076 DOI: 10.1073/pnas.1801233115] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Second messengers are employed by all organisms to regulate fundamental behaviors, including biofilm formation, motility, metabolism, and pathogenesis in bacteria. We have identified a phospholipase in the El Tor Vibrio cholerae biotype, responsible for the current cholera pandemic, that is directly activated by the second messenger 3′, 3′-cyclic GMP-AMP (cGAMP). Discovery of this proteinaceous bacterial cGAMP effector sheds light on the functions and basic principles of cGAMP signaling. Both this phospholipase and the cGAMP synthase are encoded within the VSP-1 pathogenicity island, unique to the El Tor biotype, and our findings assign a biochemical function to VSP-1 that may contribute to the epidemiological success of El Tor V. cholerae. Sensing and responding to environmental changes is essential for bacteria to adapt and thrive, and nucleotide-derived second messengers are central signaling systems in this process. The most recently identified bacterial cyclic dinucleotide second messenger, 3′, 3′-cyclic GMP-AMP (cGAMP), was first discovered in the El Tor biotype of Vibrio cholerae. The cGAMP synthase, DncV, is encoded on the VSP-1 pathogenicity island, which is found in all El Tor isolates that are responsible for the current seventh pandemic of cholera but not in the classical biotype. We determined that unregulated production of DncV inhibits growth in El Tor V. cholerae but has no effect on the classical biotype. This cGAMP-dependent phenotype can be suppressed by null mutations in vc0178 immediately 5′ of dncV in VSP-1. VC0178 [renamed as cGAMP-activated phospholipase in Vibrio (CapV)] is predicted to be a patatin-like phospholipase, and coexpression of capV and dncV is sufficient to induce growth inhibition in classical V. cholerae and Escherichia coli. Furthermore, cGAMP binds to CapV and directly activates its hydrolase activity in vitro. CapV activated by cGAMP in vivo degrades phospholipids in the cell membrane, releasing 16:1 and 18:1 free fatty acids. Together, we demonstrate that cGAMP activates CapV phospholipase activity to target the cell membrane and suggest that acquisition of this second messenger signaling pathway may contribute to the emergence of the El Tor biotype as the etiological agent behind the seventh cholera pandemic.
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29
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Knappenberger AJ, Reiss CW, Strobel SA. Structures of two aptamers with differing ligand specificity reveal ruggedness in the functional landscape of RNA. eLife 2018; 7:36381. [PMID: 29877798 PMCID: PMC6031431 DOI: 10.7554/elife.36381] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 06/05/2018] [Indexed: 01/07/2023] Open
Abstract
Two classes of riboswitches related to the ykkC guanidine-I riboswitch bind phosphoribosyl pyrophosphate (PRPP) and guanosine tetraphosphate (ppGpp). Here we report the co-crystal structure of the PRPP aptamer and its ligand. We also report the structure of the G96A point mutant that prefers ppGpp over PRPP with a dramatic 40,000-fold switch in specificity. The ends of the aptamer form a helix that is not present in the guanidine aptamer and is involved in the expression platform. In the mutant, the base of ppGpp replaces G96 in three-dimensional space. This disrupts the S-turn, which is a primary structural feature of the ykkC RNA motif. These dramatic differences in ligand specificity are achieved with minimal mutations. ykkC aptamers are therefore a prime example of an RNA fold with a rugged fitness landscape. The ease with which the ykkC aptamer acquires new specificity represents a striking case of evolvability in RNA.
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Affiliation(s)
- Andrew John Knappenberger
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States,Chemical Biology InstituteYale UniversityWest HavenUnited States
| | - Caroline Wetherington Reiss
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States,Chemical Biology InstituteYale UniversityWest HavenUnited States
| | - Scott A Strobel
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States,Chemical Biology InstituteYale UniversityWest HavenUnited States
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30
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Wang B, Wang Z, Javornik U, Xi Z, Plavec J. Computational and NMR spectroscopy insights into the conformation of cyclic di-nucleotides. Sci Rep 2017; 7:16550. [PMID: 29185472 PMCID: PMC5707406 DOI: 10.1038/s41598-017-16794-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/17/2017] [Indexed: 11/13/2022] Open
Abstract
Cyclic di-nucleotides (CDNs) are second messengers in bacteria and metazoan that are as such controlling important biological processes. Here the conformational space of CDNs was explored systematically by a combination of extensive conformational search and DFT calculations as well as NMR methods. We found that CDNs adopt pre-organized conformations in solution in which the ribose conformations are North type and glycosidic bond conformations are anti type. The overall flexibility of CDNs as well as the backbone torsion angles depend on the cyclization of the phosphodiester bond. Compared to di-nucleotides, CDNs display high rigidity in the macrocyclic moieties. Structural comparison studies demonstrate that the pre-organized conformations of CDNs highly resemble the biologically active conformations. These findings provide information for the design of small molecules to modulate CDNs signalling pathways in bacteria or as vaccine adjuvants. The rigidity of the backbone of CDNs enables the design of high order structures such as molecular cages based on CDNs analogues.
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Affiliation(s)
- Baifan Wang
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Zhenghua Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300071, P. R. China
| | - Uroš Javornik
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300071, P. R. China.
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia.
- EN-FIST Center of Excellence, Trg OF 13, 1000, Ljubljana, Slovenia.
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana, Slovenia.
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31
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Wang C, Sinn M, Stifel J, Heiler AC, Sommershof A, Hartig JS. Synthesis of All Possible Canonical (3'-5'-Linked) Cyclic Dinucleotides and Evaluation of Riboswitch Interactions and Immune-Stimulatory Effects. J Am Chem Soc 2017; 139:16154-16160. [PMID: 29056046 DOI: 10.1021/jacs.7b06141] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The cyclic dinucleotides (CDNs) c-di-GMP, c-di-AMP, and c-AMP-GMP are widely utilized as second messengers in bacteria, where they signal lifestyle changes such as motility and biofilm formation, cell wall and membrane homeostasis, virulence, and exo-electrogenesis. For all known bacterial CDNs, specific riboswitches have been identified that alter gene expression in response to the second messengers. In addition, bacterial CDNs trigger potent immune responses, making them attractive as adjuvants in immune therapies. Besides the three naturally occurring CDNs, seven further CDNs containing canonical 3'-5'-linkages are possible by combining the four natural ribonucleotides. Herein, we have synthesized all ten possible combinations of 3'-5'-linked CDNs. The binding affinity of novel CDNs and GEMM riboswitch variants was assessed utilizing a spinach aptamer fluorescence assay and in-line probing assays. The immune-stimulatory effect of CDNs was evaluated by induction of type I interferons (IFNs), and a novel CDN c-AMP-CMP was identified as a new immune-stimulatory agent.
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Affiliation(s)
- Changhao Wang
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany.,Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University , Xi'an 710119, China
| | - Malte Sinn
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , Konstanz 78457, Germany
| | - Julia Stifel
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , Konstanz 78457, Germany
| | - Anna C Heiler
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , Konstanz 78457, Germany
| | | | - Jörg S Hartig
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , Konstanz 78457, Germany
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32
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Abstract
Riboswitches are cis-acting gene regulatory elements and constitute potential targets for new antibiotics. Recent studies in this field have started to explore these targets for drug discovery. New ligands found by fragment screening, design of analogs of the natural ligands or serendipitously by phenotypic screening have shown antibacterial effects in cell assays against a range of bacteria strains and in animal models. In this review, we highlight the most advanced drug design work of riboswitch ligands and discuss the challenges in the field with respect to the development of antibiotics with a new mechanism of action.
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33
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Jones CP, Ferré-D'Amaré AR. Long-Range Interactions in Riboswitch Control of Gene Expression. Annu Rev Biophys 2017; 46:455-481. [PMID: 28375729 DOI: 10.1146/annurev-biophys-070816-034042] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Riboswitches are widespread RNA motifs that regulate gene expression in response to fluctuating metabolite concentrations. Known primarily from bacteria, riboswitches couple specific ligand binding and changes in RNA structure to mRNA expression in cis. Crystal structures of the ligand binding domains of most of the phylogenetically widespread classes of riboswitches, each specific to a particular metabolite or ion, are now available. Thus, the bound states-one end point-have been thoroughly characterized, but the unbound states have been more elusive. Consequently, it is less clear how the unbound, sensing riboswitch refolds into the ligand binding-induced output state. The ligand recognition mechanisms of riboswitches are diverse, but we find that they share a common structural strategy in positioning their binding sites at the point of the RNA three-dimensional fold where the residues farthest from one another in sequence meet. We review how riboswitch folds adhere to this fundamental strategy and propose future research directions for understanding and harnessing their ability to specifically control gene expression.
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Affiliation(s)
- Christopher P Jones
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
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34
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Hallberg ZF, Su Y, Kitto RZ, Hammond MC. Engineering and In Vivo Applications of Riboswitches. Annu Rev Biochem 2017; 86:515-539. [PMID: 28375743 DOI: 10.1146/annurev-biochem-060815-014628] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Riboswitches are common gene regulatory units mostly found in bacteria that are capable of altering gene expression in response to a small molecule. These structured RNA elements consist of two modular subunits: an aptamer domain that binds with high specificity and affinity to a target ligand and an expression platform that transduces ligand binding to a gene expression output. Significant progress has been made in engineering novel aptamer domains for new small molecule inducers of gene expression. Modified expression platforms have also been optimized to function when fused with both natural and synthetic aptamer domains. As this field expands, the use of these privileged scaffolds has permitted the development of tools such as RNA-based fluorescent biosensors. In this review, we summarize the methods that have been developed to engineer new riboswitches and highlight applications of natural and synthetic riboswitches in enzyme and strain engineering, in controlling gene expression and cellular physiology, and in real-time imaging of cellular metabolites and signals.
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Affiliation(s)
- Zachary F Hallberg
- Department of Chemistry, University of California, Berkeley, California 94720;
| | - Yichi Su
- Department of Chemistry, University of California, Berkeley, California 94720;
| | - Rebekah Z Kitto
- Department of Chemistry, University of California, Berkeley, California 94720;
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, California 94720; .,Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
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Bose D, Su Y, Marcus A, Raulet DH, Hammond MC. An RNA-Based Fluorescent Biosensor for High-Throughput Analysis of the cGAS-cGAMP-STING Pathway. Cell Chem Biol 2016; 23:1539-1549. [PMID: 27889408 DOI: 10.1016/j.chembiol.2016.10.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/02/2016] [Accepted: 10/25/2016] [Indexed: 12/15/2022]
Abstract
In mammalian cells, the second messenger (2'-5',3'-5') cyclic guanosine monophosphate-adenosine monophosphate (2',3'-cGAMP), is produced by the cytosolic DNA sensor cGAMP synthase (cGAS), and subsequently bound by the stimulator of interferon genes (STING) to trigger interferon response. Thus, the cGAS-cGAMP-STING pathway plays a critical role in pathogen detection, as well as pathophysiological conditions including cancer and autoimmune disorders. However, studying and targeting this immune signaling pathway has been challenging due to the absence of tools for high-throughput analysis. We have engineered an RNA-based fluorescent biosensor that responds to 2',3'-cGAMP. The resulting "mix-and-go" cGAS activity assay shows excellent statistical reliability as a high-throughput screening (HTS) assay and distinguishes between direct and indirect cGAS inhibitors. Furthermore, the biosensor enables quantitation of 2',3'-cGAMP in mammalian cell lysates. We envision this biosensor-based assay as a resource to study the cGAS-cGAMP-STING pathway in the context of infectious diseases, cancer immunotherapy, and autoimmune diseases.
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Affiliation(s)
- Debojit Bose
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Yichi Su
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Assaf Marcus
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - David H Raulet
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA.
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Orr MW, Galperin MY, Lee VT. Sustained sensing as an emerging principle in second messenger signaling systems. Curr Opin Microbiol 2016; 34:119-126. [PMID: 27700990 DOI: 10.1016/j.mib.2016.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 08/25/2016] [Accepted: 08/31/2016] [Indexed: 11/18/2022]
Abstract
Bacteria utilize a diverse set of nucleotide second messengers to regulate cellular responses by binding macromolecular receptors (RNAs and proteins). Recent studies on cyclic di-GMP (c-di-GMP) have shown that this signaling molecule binds multiple receptors to regulate different steps in the same biological process. We propose this property of the same molecule regulating multiple steps in the same process is biologically meaningful and have termed this phenomenon 'sustained sensing'. Here, we discuss the recent findings that support the concept of sustained sensing of c-di-GMP levels and provide additional examples that support the utilization of sustained sensing by other second messengers. Sustained sensing may be widespread in bacteria and provides an additional level of complexity in prokaryotic signal transduction networks.
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Affiliation(s)
- Mona W Orr
- Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD, USA; Maryland Pathogen Research Institute, University of Maryland at College Park, College Park, MD, USA
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Vincent T Lee
- Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD, USA; Maryland Pathogen Research Institute, University of Maryland at College Park, College Park, MD, USA.
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Wang YC, Chin KH, Tu ZL, He J, Jones CJ, Sanchez DZ, Yildiz FH, Galperin MY, Chou SH. Nucleotide binding by the widespread high-affinity cyclic di-GMP receptor MshEN domain. Nat Commun 2016; 7:12481. [PMID: 27578558 PMCID: PMC5013675 DOI: 10.1038/ncomms12481] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Accepted: 07/06/2016] [Indexed: 12/28/2022] Open
Abstract
C-di-GMP is a bacterial second messenger regulating various cellular functions. Many bacteria contain c-di-GMP-metabolizing enzymes but lack known c-di-GMP receptors. Recently, two MshE-type ATPases associated with bacterial type II secretion system and type IV pilus formation were shown to specifically bind c-di-GMP. Here we report crystal structure of the MshE N-terminal domain (MshEN1-145) from Vibrio cholerae in complex with c-di-GMP at a 1.37 Å resolution. This structure reveals a unique c-di-GMP-binding mode, featuring a tandem array of two highly conserved binding motifs, each comprising a 24-residue sequence RLGxx(L/V/I)(L/V/I)xxG(L/V/I)(L/V/I)xxxxLxxxLxxQ that binds half of the c-di-GMP molecule, primarily through hydrophobic interactions. Mutating these highly conserved residues markedly reduces c-di-GMP binding and biofilm formation by V. cholerae. This c-di-GMP-binding motif is present in diverse bacterial proteins exhibiting binding affinities ranging from 0.5 μM to as low as 14 nM. The MshEN domain contains the longest nucleotide-binding motif reported to date. Cyclic-di-GMP is a bacterial second messenger that binds to the regulatory domain of ATPases of some bacteria. Here, the authors report the crystal structure of this interaction, identify a cyclic-di-GMP binding mode, and show that this interaction might be important for bacterial biofilm formation.
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Affiliation(s)
- Yu-Chuan Wang
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
| | - Ko-Hsin Chin
- Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
| | - Zhi-Le Tu
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, People's Republic of China
| | - Christopher J Jones
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, USA
| | - David Zamorano Sanchez
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, USA
| | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, USA
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA
| | - Shan-Ho Chou
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China.,Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
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Wang XC, Wilson SC, Hammond MC. Next-generation RNA-based fluorescent biosensors enable anaerobic detection of cyclic di-GMP. Nucleic Acids Res 2016; 44:e139. [PMID: 27382070 PMCID: PMC5041473 DOI: 10.1093/nar/gkw580] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 06/16/2016] [Indexed: 12/14/2022] Open
Abstract
Bacteria occupy a diverse set of environmental niches with differing oxygen availability. Anaerobic environments such as mammalian digestive tracts and industrial reactors harbor an abundance of both obligate and facultative anaerobes, many of which play significant roles in human health and biomanufacturing. Studying bacterial function under partial or fully anaerobic conditions, however, is challenging given the paucity of suitable live-cell imaging tools. Here, we introduce a series of RNA-based fluorescent biosensors that respond selectively to cyclic di-GMP, an intracellular bacterial second messenger that controls cellular motility and biofilm formation. We demonstrate the utility of these biosensors in vivo under both aerobic and anaerobic conditions, and we show that biosensor expression does not interfere with the native motility phenotype. Together, our results attest to the effectiveness and versatility of RNA-based fluorescent biosensors, priming further development and application of these and other analogous sensors to study host–microbial and microbial–microbial interactions through small molecule signals.
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Affiliation(s)
- Xin C Wang
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Stephen C Wilson
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Ming C Hammond
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA Department of Chemistry, University of California, Berkeley, CA 94720, USA
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Li S, Hwang XY, Stav S, Breaker RR. The yjdF riboswitch candidate regulates gene expression by binding diverse azaaromatic compounds. RNA (NEW YORK, N.Y.) 2016; 22:530-41. [PMID: 26843526 PMCID: PMC4793209 DOI: 10.1261/rna.054890.115] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/10/2015] [Indexed: 05/21/2023]
Abstract
The yjdF motif RNA is an orphan riboswitch candidate that almost exclusively associates with the yjdF protein-coding gene in many bacteria. The function of the YjdF protein is unknown, which has made speculation regarding the natural ligand for this putative riboswitch unusually challenging. By using a structure-probing assay for ligand binding, we found that a surprisingly broad diversity of nitrogen-containing aromatic heterocycles, or "azaaromatics," trigger near-identical changes in the structures adopted by representative yjdF motif RNAs. Regions of the RNA that undergo ligand-induced structural modulation reside primarily in portions of the putative aptamer region that are highly conserved in nucleotide sequence, as is typical for riboswitches. Some azaaromatic molecules are bound by the RNA with nanomolar dissociation constants, and a subset of these ligands activate riboswitch-mediated gene expression in cells. Furthermore, genetic elements most commonly adjacent to the yjdF motif RNA or to the yjdF protein-coding region are homologous to protein regulators implicated in mitigating the toxic effects of diverse phenolic acids or polycyclic compounds. Although the precise type of natural ligand sensed by yjdF motif RNAs remains unknown, our findings suggest that this riboswitch class might serve as part of a genetic response system to toxic or signaling compounds with chemical structures similar to azaaromatics.
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Affiliation(s)
- Sanshu Li
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Xue Ying Hwang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Shira Stav
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Ronald R Breaker
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, USA Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
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Furukawa A, Maejima T, Matsumura S, Ikawa Y. Characterization of an RNA receptor motif that recognizes a GCGA tetraloop. Biosci Biotechnol Biochem 2016; 80:1386-9. [PMID: 26967268 DOI: 10.1080/09168451.2016.1156483] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Tertiary interactions between a new RNA motif and RNA tetraloops were analyzed to determine whether this new motif shows preference for a GCGA tetraloop. In the structural context of a ligase ribozyme, this motif discriminated GCGA loop from 3 other tetraloops. The affinity between the GCGA loop and its receptor is strong enough to carry out the ribozyme activity.
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Affiliation(s)
- Airi Furukawa
- a Department of Chemistry , Graduate School of Science and Engineering, University of Toyama , Toyama , Japan
| | - Takaya Maejima
- a Department of Chemistry , Graduate School of Science and Engineering, University of Toyama , Toyama , Japan
| | - Shigeyoshi Matsumura
- a Department of Chemistry , Graduate School of Science and Engineering, University of Toyama , Toyama , Japan
| | - Yoshiya Ikawa
- a Department of Chemistry , Graduate School of Science and Engineering, University of Toyama , Toyama , Japan
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Hybrid promiscuous (Hypr) GGDEF enzymes produce cyclic AMP-GMP (3', 3'-cGAMP). Proc Natl Acad Sci U S A 2016; 113:1790-5. [PMID: 26839412 DOI: 10.1073/pnas.1515287113] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Over 30 years ago, GGDEF domain-containing enzymes were shown to be diguanylate cyclases that produce cyclic di-GMP (cdiG), a second messenger that modulates the key bacterial lifestyle transition from a motile to sessile biofilm-forming state. Since then, the ubiquity of genes encoding GGDEF proteins in bacterial genomes has established the dominance of cdiG signaling in bacteria. However, the observation that proteobacteria encode a large number of GGDEF proteins, nearing 1% of coding sequences in some cases, raises the question of why bacteria need so many GGDEF enzymes. In this study, we reveal that a subfamily of GGDEF enzymes synthesizes the asymmetric signaling molecule cyclic AMP-GMP (cAG or 3', 3'-cGAMP). This discovery is unexpected because GGDEF enzymes function as symmetric homodimers, with each monomer binding to one substrate NTP. Detailed analysis of the enzyme from Geobacter sulfurreducens showed it is a dinucleotide cyclase capable of switching the major cyclic dinucleotide (CDN) produced based on ATP-to-GTP ratios. We then establish through bioinformatics and activity assays that hybrid CDN-producing and promiscuous substrate-binding (Hypr) GGDEF enzymes are found in other deltaproteobacteria. Finally, we validated the predictive power of our analysis by showing that cAG is present in surface-grown Myxococcus xanthus. This study reveals that GGDEF enzymes make alternative cyclic dinucleotides to cdiG and expands the role of this widely distributed enzyme family to include regulation of cAG signaling.
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Molecular prejudice: RNA discrimination against purines allows response to a cellular alarm. Nat Struct Mol Biol 2016; 22:754-6. [PMID: 26439636 DOI: 10.1038/nsmb.3095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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43
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Abstract
Signal sensing in bacteria has traditionally been attributed to protein-based factors. It is however becoming increasingly clear that bacteria also exploit RNAs to serve this role. This review discusses how key developmental processes in bacteria, such as community formation, choice of a sessile versus motile lifestyle, or vegetative growth versus dormant spore formation may be governed by signal sensing RNAs. The signaling molecules that affect these processes, the RNAs that sense these molecules and the underlying molecular basis for specific signal-response are discussed here.
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Affiliation(s)
- Arati Ramesh
- National Center for Biological Sciences, GKVK Campus, Bellary Road, Bangalore 560065, India.
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Jones CP, Ferré-D'Amaré AR. Recognition of the bacterial alarmone ZMP through long-distance association of two RNA subdomains. Nat Struct Mol Biol 2015; 22:679-85. [PMID: 26280533 PMCID: PMC4824399 DOI: 10.1038/nsmb.3073] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/22/2015] [Indexed: 12/22/2022]
Abstract
The bacterial alarmone 5-aminoimidazole-4-carboxamide riboside 5'-triphosphate (ZTP), derived from the monophosphorylated purine precursor ZMP, accumulates during folate starvation. ZTP regulates genes involved in purine and folate metabolism through a cognate riboswitch. The linker connecting this riboswitch’s two sub-domains varies in length by over 100 nucleotides. We report the co-crystal structure of the Fusobacterium ulcerans riboswitch bound to ZMP, which spans the two sub-domains whose interface also comprises a pseudoknot and ribose zipper. The riboswitch recognizes the carboxamide oxygen of ZMP through an unprecedented inner-sphere coordination with a Mg2+ ion. We demonstrate that the affinity of the riboswitch for ZMP is modulated by the linker length. Notably, ZMP can bind to the two sub-domains together even when synthesized as separate RNAs. The ZTP riboswitch demonstrates how specific small-molecule binding can drive association of distant non-coding RNA domains to regulate gene expression.
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Affiliation(s)
- Christopher P Jones
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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Global RNA Fold and Molecular Recognition for a pfl Riboswitch Bound to ZMP, a Master Regulator of One-Carbon Metabolism. Structure 2015; 23:1375-1381. [PMID: 26118534 DOI: 10.1016/j.str.2015.05.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 05/04/2015] [Accepted: 05/05/2015] [Indexed: 11/20/2022]
Abstract
ZTP, the pyrophosphorylated analog of ZMP (5-amino-4-imidazole carboxamide ribose-5'-monophosphate), was identified as an alarmone that senses 10-formyl-tetrahydroflate deficiency in bacteria. Recently, a pfl riboswitch was identified that selectively binds ZMP and regulates genes associated with purine biosynthesis and one-carbon metabolism. We report on the structure of the ZMP-bound Thermosinus carboxydivorans pfl riboswitch sensing domain, thereby defining the pseudoknot-based tertiary RNA fold, the binding-pocket architecture, and principles underlying ligand recognition specificity. Molecular recognition involves shape complementarity, with the ZMP 5-amino and carboxamide groups paired with the Watson-Crick edge of an invariant uracil, and the imidazole ring sandwiched between guanines, while the sugar hydroxyls form intermolecular hydrogen bond contacts. The burial of the ZMP base and ribose moieties, together with unanticipated coordination of the carboxamide by Mg(2+), contrasts with exposure of the 5'-phosphate to solvent. Our studies highlight the principles underlying RNA-based recognition of ZMP, a master regulator of one-carbon metabolism.
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