1
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Mwangi MN, Yonkunas MJ, Ageeli AA, McGovern-Gooch KR, Yilmaz S, Baird NJ. A Newly Identified Peripheral Duplex Anchors and Stabilizes the MALAT1 Triplex. Biochemistry 2024; 63:2280-2292. [PMID: 39190685 PMCID: PMC11411715 DOI: 10.1021/acs.biochem.4c00156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/29/2024]
Abstract
The accumulation of the 8-kb oncogenic long noncoding MALAT1 RNA in cells is dependent on the presence of a protective triple helix structure at the 3' terminus. While recent studies have examined the functional importance of numerous base triples within the triplex and its immediately adjacent base pairs, the functional importance of peripheral duplex elements has not been thoroughly investigated. To investigate the functional importance of a peripheral linker region that was previously described as unstructured, we employed a variety of assays including thermal melting, protection from exonucleolytic degradation by RNase R, small-angle X-ray scattering, biochemical ligation and binding assays, and computational modeling. Our results demonstrate the presence of a duplex within this linker that enhances the functional stability of the triplex in vitro, despite its location more than 40 Å from the 3' terminus. We present a full-length model of the MALAT1 triple helix-containing RNA having an extended rod-like structure and comprising 33 layers of coaxial stacking interactions. Taken together with recent research on a homologous triplex, our results demonstrate that peripheral elements anchor and stabilize triplexes in vitro. Such peripheral elements may also contribute to the formation and stability of some triple helices in vivo.
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Affiliation(s)
- Mary N Mwangi
- Department of Chemistry & Biochemistry, Saint Joseph's University, 600 S. 43rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Michael J Yonkunas
- Department of Chemistry & Biochemistry, Saint Joseph's University, 600 S. 43rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Abeer A Ageeli
- Department of Chemistry & Biochemistry, Saint Joseph's University, 600 S. 43rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Kayleigh R McGovern-Gooch
- Department of Chemistry & Biochemistry, Saint Joseph's University, 600 S. 43rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Sevde Yilmaz
- Department of Chemistry & Biochemistry, Saint Joseph's University, 600 S. 43rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Nathan J Baird
- Department of Chemistry & Biochemistry, Saint Joseph's University, 600 S. 43rd Street, Philadelphia, Pennsylvania 19104, United States
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2
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Giarimoglou N, Kouvela A, Zhang J, Stamatopoulou V, Stathopoulos C. Structural idiosyncrasies of glycyl T-box riboswitches among pathogenic bacteria. RNA (NEW YORK, N.Y.) 2024; 30:1328-1344. [PMID: 38981655 PMCID: PMC11404447 DOI: 10.1261/rna.080071.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Accepted: 06/17/2024] [Indexed: 07/11/2024]
Abstract
T-box riboswitches are widespread bacterial regulatory noncoding RNAs that directly interact with tRNAs and switch conformations to regulate the transcription or translation of genes related to amino acid metabolism. Recent studies in Bacilli have revealed the core mechanisms of T-boxes that enable multivalent, specific recognition of both the identity and aminoacylation status of the tRNA substrates. However, in-depth knowledge on a vast number of T-boxes in other bacterial species remains scarce, although a remarkable structural diversity, particularly among pathogens, is apparent. In the present study, analysis of T-boxes that control the transcription of glycyl-tRNA synthetases from four prominent human pathogens revealed significant structural idiosyncrasies. Nonetheless, these diverse T-boxes maintain functional T-box:tRNAGly interactions both in vitro and in vivo. Probing analysis not only validated recent structural observations, but also expanded our knowledge on the substantial diversities among T-boxes and suggest interesting distinctions from the canonical Bacilli T-boxes. Surprisingly, some glycyl T-boxes seem to redirect the T-box trajectory in the absence of recognizable K-turns or contain Stem II modules that are generally absent in glycyl T-boxes. These results consolidate the notion of a lineage-specific diversification and elaboration of the T-box mechanism and corroborate the potential of T-boxes as promising species-specific RNA targets for next-generation antibacterial compounds.
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MESH Headings
- Riboswitch/genetics
- Nucleic Acid Conformation
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Bacterial/chemistry
- Gene Expression Regulation, Bacterial
- Glycine-tRNA Ligase/genetics
- Glycine-tRNA Ligase/metabolism
- Glycine-tRNA Ligase/chemistry
- RNA, Transfer, Gly/metabolism
- RNA, Transfer, Gly/genetics
- RNA, Transfer, Gly/chemistry
- Base Sequence
- Bacteria/genetics
- Bacteria/metabolism
- Humans
- RNA, Transfer/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/chemistry
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892, USA
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3
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Umuhire Juru A, Ghirlando R, Zhang J. Structural basis of tRNA recognition by the widespread OB fold. Nat Commun 2024; 15:6385. [PMID: 39075051 PMCID: PMC11286949 DOI: 10.1038/s41467-024-50730-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 07/18/2024] [Indexed: 07/31/2024] Open
Abstract
The widespread oligonucleotide/oligosaccharide-binding (OB)-fold recognizes diverse substrates from sugars to nucleic acids and proteins, and plays key roles in genome maintenance, transcription, translation, and tRNA metabolism. OB-containing bacterial Trbp and yeast Arc1p proteins are thought to recognize the tRNA elbow or anticodon regions. Here we report a 2.6 Å co-crystal structure of Aquifex aeolicus Trbp111 bound to tRNAIle, which reveals that Trbp recognizes tRNAs solely by capturing their 3' ends. Structural, mutational, and biophysical analyses show that the Trbp/EMAPII-like OB fold precisely recognizes the single-stranded structure, 3' terminal location, and specific sequence of the 3' CA dinucleotide - a universal feature of mature tRNAs. Arc1p supplements its OB - tRNA 3' end interaction with additional contacts that involve an adjacent basic region and the tRNA body. This study uncovers a previously unrecognized mode of tRNA recognition by an ancient protein fold, and provides insights into protein-mediated tRNA aminoacylation, folding, localization, trafficking, and piracy.
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Affiliation(s)
- Aline Umuhire Juru
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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4
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Skeparnias I, Zhang J. Structural basis of NEAT1 lncRNA maturation and menRNA instability. Nat Struct Mol Biol 2024:10.1038/s41594-024-01361-z. [PMID: 39026030 DOI: 10.1038/s41594-024-01361-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 06/26/2024] [Indexed: 07/20/2024]
Abstract
NEAT1 long noncoding RNA orchestrates paraspeckle assembly and impacts tumorigenesis, fertility and immunity. Its maturation requires RNase P cleavage yielding an unstable transfer RNA-like multiple endocrine neoplasia-β tRNA-like transcript (menRNA) due to CCACCA addition. Here we report the crystal structure of human menRNA, which partially mimics tRNAs to drive RNase P and ELAC2 processing. Biophysical analyses uncover an RNA-centric, riboswitch-like mechanism whereby the nascent CCA reshapes the RNA folding landscape and propels a spontaneous conformational isomerization that directs repeat CCA addition, marking the menRNA and defective tRNAs for degradation.
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Affiliation(s)
- Ilias Skeparnias
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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5
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Skeparnias I, Bou-Nader C, Anastasakis DG, Fan L, Wang YX, Hafner M, Zhang J. Structural basis of MALAT1 RNA maturation and mascRNA biogenesis. Nat Struct Mol Biol 2024:10.1038/s41594-024-01340-4. [PMID: 38956168 DOI: 10.1038/s41594-024-01340-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 05/29/2024] [Indexed: 07/04/2024]
Abstract
The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) long noncoding RNA (lncRNA) has key roles in regulating transcription, splicing, tumorigenesis, etc. Its maturation and stabilization require precise processing by RNase P, which simultaneously initiates the biogenesis of a 3' cytoplasmic MALAT1-associated small cytoplasmic RNA (mascRNA). mascRNA was proposed to fold into a transfer RNA (tRNA)-like secondary structure but lacks eight conserved linking residues required by the canonical tRNA fold. Here we report crystal structures of human mascRNA before and after processing, which reveal an ultracompact, quasi-tRNA-like structure. Despite lacking all linker residues, mascRNA faithfully recreates the characteristic 'elbow' feature of tRNAs to recruit RNase P and ElaC homolog protein 2 (ELAC2) for processing, which exhibit distinct substrate specificities. Rotation and repositioning of the D-stem and anticodon regions preclude mascRNA from aminoacylation, avoiding interference with translation. Therefore, a class of metazoan lncRNA loci uses a previously unrecognized, unusually streamlined quasi-tRNA architecture to recruit select tRNA-processing enzymes while excluding others to drive bespoke RNA biogenesis, processing and maturation.
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Affiliation(s)
- Ilias Skeparnias
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Dimitrios G Anastasakis
- RNA Molecular Biology Laboratory, National Institute for Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, USA
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, USA
| | - Yun-Xing Wang
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, USA
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Markus Hafner
- RNA Molecular Biology Laboratory, National Institute for Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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6
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Lu W, Terasaka N, Sakaguchi Y, Suzuki T, Suzuki T, Suga H. An anticodon-sensing T-boxzyme generates the elongator nonproteinogenic aminoacyl-tRNA in situ of a custom-made translation system for incorporation. Nucleic Acids Res 2024; 52:3938-3949. [PMID: 38477328 DOI: 10.1093/nar/gkae151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/24/2024] [Accepted: 02/17/2024] [Indexed: 03/14/2024] Open
Abstract
In the hypothetical RNA world, ribozymes could have acted as modern aminoacyl-tRNA synthetases (ARSs) to charge tRNAs, thus giving rise to the peptide synthesis along with the evolution of a primitive translation apparatus. We previously reported a T-boxzyme, Tx2.1, which selectively charges initiator tRNA with N-biotinyl-phenylalanine (BioPhe) in situ in a Flexible In-vitro Translation (FIT) system to produce BioPhe-initiating peptides. Here, we performed in vitro selection of elongation-capable T-boxzymes (elT-boxzymes), using para-azido-l-phenylalanine (PheAZ) as an acyl-donor. We implemented a new strategy to enrich elT-boxzyme-tRNA conjugates that self-aminoacylated on the 3'-terminus selectively. One of them, elT32, can charge PheAZ onto tRNA in trans in response to its cognate anticodon. Further evolution of elT32 resulted in elT49, with enhanced aminoacylation activity. We have demonstrated the translation of a PheAZ-containing peptide in an elT-boxzyme-integrated FIT system, revealing that elT-boxzymes are able to generate the PheAZ-tRNA in response to the cognate anticodon in situ of a custom-made translation system. This study, together with Tx2.1, illustrates a scenario where a series of ribozymes could have overseen aminoacylation and co-evolved with a primitive RNA-based translation system.
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Affiliation(s)
- Wei Lu
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Naohiro Terasaka
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Department of Medical Biochemistry, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0125, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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7
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Niu X, Xu Z, Zhang Y, Zuo X, Chen C, Fang X. Structural and dynamic mechanisms for coupled folding and tRNA recognition of a translational T-box riboswitch. Nat Commun 2023; 14:7394. [PMID: 37968328 PMCID: PMC10651847 DOI: 10.1038/s41467-023-43232-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/03/2023] [Indexed: 11/17/2023] Open
Abstract
T-box riboswitches are unique riboregulators where gene regulation is mediated through interactions between two highly structured RNAs. Despite extensive structural insights, how RNA-RNA interactions drive the folding and structural transitions of T-box to achieve functional conformations remains unclear. Here, by combining SAXS, single-molecule FRET and computational modeling, we elaborate the folding energy landscape of a translational T-box aptamer consisting of stems I, II and IIA/B, which Mg2+-induced global folding and tRNA binding are cooperatively coupled. smFRET measurements reveal that high Mg2+ stabilizes IIA/B and its stacking on II, which drives the pre-docking of I and II into a competent conformation, subsequent tRNA binding promotes docking of I and II to form a high-affinity tRNA binding groove, of which the essentiality of IIA/B and S-turn in II is substantiated with mutational analysis. We highlight a delicate balance among Mg2+, the intra- and intermolecular RNA-RNA interactions in modulating RNA folding and function.
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Affiliation(s)
- Xiaolin Niu
- Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhonghe Xu
- Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yufan Zhang
- Key Laboratory of RNA Science and Engineering, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaobing Zuo
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Chunlai Chen
- Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China.
| | - Xianyang Fang
- Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Key Laboratory of RNA Science and Engineering, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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8
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Suddala KC, Yoo J, Fan L, Zuo X, Wang YX, Chung HS, Zhang J. Direct observation of tRNA-chaperoned folding of a dynamic mRNA ensemble. Nat Commun 2023; 14:5438. [PMID: 37673863 PMCID: PMC10482949 DOI: 10.1038/s41467-023-41155-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 08/24/2023] [Indexed: 09/08/2023] Open
Abstract
T-box riboswitches are multi-domain noncoding RNAs that surveil individual amino acid availabilities in most Gram-positive bacteria. T-boxes directly bind specific tRNAs, query their aminoacylation status to detect starvation, and feedback control the transcription or translation of downstream amino-acid metabolic genes. Most T-boxes rapidly recruit their cognate tRNA ligands through an intricate three-way stem I-stem II-tRNA interaction, whose establishment is not understood. Using single-molecule FRET, SAXS, and time-resolved fluorescence, we find that the free T-box RNA assumes a broad distribution of open, semi-open, and closed conformations that only slowly interconvert. tRNA directly binds all three conformers with distinct kinetics, triggers nearly instantaneous collapses of the open conformations, and returns the T-box RNA to their pre-binding conformations upon dissociation. This scissors-like dynamic behavior is enabled by a hinge-like pseudoknot domain which poises the T-box for rapid tRNA-induced domain closure. This study reveals tRNA-chaperoned folding of flexible, multi-domain mRNAs through a Venus flytrap-like mechanism.
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Affiliation(s)
- Krishna C Suddala
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Janghyun Yoo
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Lixin Fan
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, 21702, USA
| | - Xiaobing Zuo
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Yun-Xing Wang
- Basic Science Program, Frederick National Laboratory for Cancer Research, Small-Angle X-Ray Scattering Core Facility of National Cancer Institute, Frederick, MD, 21702, USA
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
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9
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Jia X, Zhang C, Luo B, Frandsen JK, Watkins AM, Li K, Zhang M, Wei X, Yang Y, Henkin TM, Su Z. Cryo-EM-guided engineering of T-box-tRNA modules with enhanced selectivity and sensitivity in translational regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.28.530422. [PMID: 36909519 PMCID: PMC10002618 DOI: 10.1101/2023.02.28.530422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Riboswitches are non-coding RNA elements that play vital roles in regulating gene expression. Their specific ligand-dependent structural reorganization facilitates their use as templates for design of engineered RNA switches for therapeutics, nanotechnology and synthetic biology. T-box riboswitches bind tRNAs to sense aminoacylation and control gene expression via transcription attenuation or translation inhibition. Here we determine the cryo-EM structure of the wild-type Mycobacterium smegmatis ileS T-box in complex with its cognate tRNA Ile . This structure shows a very flexible antisequestrator region that tolerates both 3'-OH and 2',3'-cyclic phosphate modification at the 3' end of tRNA Ile . Elongation of one helical turn (11-base pair) in both the tRNA acceptor arm and T-box Stem III maintains T-box-tRNA complex formation and increases the selectivity for tRNA 3' end modification. Moreover, elongation of Stem III results in ∼6-fold tighter binding to tRNA, which leads to increased sensitivity of downstream translational regulation indicated by precedent translation. Our results demonstrate that cryo-EM can guide RNA engineering to design improved riboswitch modules for translational regulation, and potentially a variety of additional functions.
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10
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Zhang J. Probing RNA Structures and Interactions Using Fluorescence Lifetime Analyses. Methods Mol Biol 2023; 2568:13-23. [PMID: 36227559 PMCID: PMC11268537 DOI: 10.1007/978-1-0716-2687-0_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Structural analyses of large, complex noncoding RNAs continue to lag behind their rapid discovery and functional descriptions. Site-specifically incorporated, minimally invasive fluorescent probes such as 2-aminopurine (2AP) and pyrrolo-cytosine (PyC) have provided essential complementary information about local RNA structure, conformational dynamics, and interactions. Here I describe a protocol that benchmarks and correlates local RNA conformations with their respective fluorescence lifetimes, as a general technique that confers key advantages over fluorescence intensity-based methods. The observation that fluorescence lifetimes are more sensitive to local structures than sequence contexts suggests broad utility across diverse RNA and ribonucleoprotein systems.
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Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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11
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Sapkota KP, Li S, Zhang J. Cotranscriptional Assembly and Native Purification of Large RNA-RNA Complexes for Structural Analyses. Methods Mol Biol 2023; 2568:1-12. [PMID: 36227558 PMCID: PMC11275850 DOI: 10.1007/978-1-0716-2687-0_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Recent technological developments such as cryogenic electron microscopy (Cryo-EM) and X-ray free electron lasers (XFEL) have significantly expanded the available toolkit to visualize large, complex noncoding RNAs and their complexes. Consequently, the quality of the RNA sample, as measured by its chemical monodispersity and conformational homogeneity, has become the bottleneck that frequently precludes effective structural analyses. Here we describe a general RNA sample preparation protocol that combines cotranscriptional RNA folding and RNA-RNA complex assembly, followed by native purification of stoichiometric complexes. We illustrate and discuss the utility of this versatile method in overcoming RNA misfolding and enabling the structural and mechanistic elucidations of the T-box riboswitch-tRNA complexes.
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Affiliation(s)
- Krishna P Sapkota
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Shuang Li
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
- Structural Biochemistry Unit, National Institute of Dental and Craniofacial Research, Bethesda, MD, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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12
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Vikram, Mishra V, Rana A, Ahire JJ. Riboswitch-mediated regulation of riboflavin biosynthesis genes in prokaryotes. 3 Biotech 2022; 12:278. [PMID: 36275359 PMCID: PMC9474784 DOI: 10.1007/s13205-022-03348-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 09/02/2022] [Indexed: 11/01/2022] Open
Abstract
Prokaryotic organisms frequently use riboswitches to quantify intracellular metabolite concentration via high-affinity metabolite receptors. Riboswitches possess a metabolite-sensing system that controls gene regulation in a cis-acting fashion at the initiation of transcriptional/translational level by binding with a specific metabolite and controlling various biochemical pathways. Riboswitch binds with flavin mononucleotide (FMN), a phosphorylated form of riboflavin and controls gene expression involved in riboflavin biosynthesis and transport pathway. The first step of the riboflavin biosynthesis pathway is initiated by the conversion of guanine nucleotide triphosphate (GTP), which is an intermediate of the purine biosynthesis pathway. An alternative pentose phosphate pathway of riboflavin biosynthesis includes the enzymatic conversion of ribulose-5-phosphate into 3, 4 dihydroxy-2-butanone-4-phosphates by DHBP synthase. The product of ribAB interferes with both GTP cyclohydrolase II as well as DHBP synthase activities, which catalyze the cleavage of GTP and converts DHBP Ribu5P in the initial steps of both riboflavin biosynthesis branches. Riboswitches are located in the 5' untranslated region (5' UTR) of messenger RNAs and contain an aptamer domain (highly conserved in sequence) where metabolite binding leads to a conformational change in an aptamer domain, which modulate the regulation of gene expression located on bacterial mRNA. In this review, we focus on how riboswitch regulates the riboflavin biosynthesis pathway in Bacillus subtilis and Lactobacillus plantarum.
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Affiliation(s)
- Vikram
- Department of Basic and Applied Sciences, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonipat, Haryana India
| | - Vijendra Mishra
- Department of Basic and Applied Sciences, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonipat, Haryana India
| | - Ananya Rana
- Department of Basic and Applied Sciences, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonipat, Haryana India
| | - Jayesh J. Ahire
- Centre for Research and Development, Unique Biotech Ltd., Plot No. 2, Phase II, MN Park, Hyderabad, Telangana India
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13
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Giarimoglou N, Kouvela A, Maniatis A, Papakyriakou A, Zhang J, Stamatopoulou V, Stathopoulos C. A Riboswitch-Driven Era of New Antibacterials. Antibiotics (Basel) 2022; 11:antibiotics11091243. [PMID: 36140022 PMCID: PMC9495366 DOI: 10.3390/antibiotics11091243] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/01/2022] [Accepted: 09/08/2022] [Indexed: 11/26/2022] Open
Abstract
Riboswitches are structured non-coding RNAs found in the 5′ UTR of important genes for bacterial metabolism, virulence and survival. Upon the binding of specific ligands that can vary from simple ions to complex molecules such as nucleotides and tRNAs, riboswitches change their local and global mRNA conformations to affect downstream transcription or translation. Due to their dynamic nature and central regulatory role in bacterial metabolism, riboswitches have been exploited as novel RNA-based targets for the development of new generation antibacterials that can overcome drug-resistance problems. During recent years, several important riboswitch structures from many bacterial representatives, including several prominent human pathogens, have shown that riboswitches are ideal RNA targets for new compounds that can interfere with their structure and function, exhibiting much reduced resistance over time. Most interestingly, mainstream antibiotics that target the ribosome have been shown to effectively modulate the regulatory behavior and capacity of several riboswitches, both in vivo and in vitro, emphasizing the need for more in-depth studies and biological evaluation of new antibiotics. Herein, we summarize the currently known compounds that target several main riboswitches and discuss the role of mainstream antibiotics as modulators of T-box riboswitches, in the dawn of an era of novel inhibitors that target important bacterial regulatory RNAs.
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Alexandros Maniatis
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Athanasios Papakyriakou
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi, 15341 Athens, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | | | - Constantinos Stathopoulos
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
- Correspondence: ; Tel.: +30-2610-997932
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14
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Giarimoglou N, Kouvela A, Patsi I, Zhang J, Stamatopoulou V, Stathopoulos C. Lineage-specific insertions in T-box riboswitches modulate antibiotic binding and action. Nucleic Acids Res 2022; 50:5834-5849. [PMID: 35580054 PMCID: PMC9177973 DOI: 10.1093/nar/gkac359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/21/2022] [Accepted: 05/11/2022] [Indexed: 01/27/2023] Open
Abstract
T-box riboswitches (T-boxes) are essential RNA regulatory elements with a remarkable structural diversity, especially among bacterial pathogens. In staphylococci, all glyS T-boxes synchronize glycine supply during synthesis of nascent polypeptides and cell wall formation and are characterized by a conserved and unique insertion in their antiterminator/terminator domain, termed stem Sa. Interestingly, in Staphylococcus aureus the stem Sa can accommodate binding of specific antibiotics, which in turn induce robust and diverse effects on T-box-mediated transcription. In the present study, domain swap mutagenesis and probing analysis were performed to decipher the role of stem Sa. Deletion of stem Sa significantly reduces both the S. aureus glyS T-box-mediated transcription readthrough levels and the ability to discriminate among tRNAGly isoacceptors, both in vitro and in vivo. Moreover, the deletion inverted the previously reported stimulatory effects of specific antibiotics. Interestingly, stem Sa insertion in the terminator/antiterminator domain of Geobacillus kaustophilus glyS T-box, which lacks this domain, resulted in elevated transcription in the presence of tigecycline and facilitated discrimination among proteinogenic and nonproteinogenic tRNAGly isoacceptors. Overall, stem Sa represents a lineage-specific structural feature required for efficient staphylococcal glyS T-box-mediated transcription and it could serve as a species-selective druggable target through its ability to modulate antibiotic binding.
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Ioanna Patsi
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
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15
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tRNA Fusion to Streamline RNA Structure Determination: Case Studies in Probing Aminoacyl-tRNA Sensing Mechanisms by the T-Box Riboswitch. CRYSTALS 2022. [DOI: 10.3390/cryst12050694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
RNAs are prone to misfolding and are often more challenging to crystallize and phase than proteins. Here, we demonstrate that tRNA fusion can streamline the crystallization and structure determination of target RNA molecules. This strategy was applied to the T-box riboswitch system to capture a dynamic interaction between the tRNA 3′-UCCA tail and the T-box antiterminator, which senses aminoacylation. We fused the T-box antiterminator domain to the tRNA anticodon arm to capture the intended interaction through crystal packing. This approach drastically improved the probability of crystallization and successful phasing. Multiple structure snapshots captured the antiterminator loop in an open conformation with some resemblance to that observed in the recent co-crystal structures of the full-length T box riboswitch–tRNA complex, which contrasts the resting, closed conformation antiterminator observed in an earlier NMR study. The anticipated tRNA acceptor–antiterminator interaction was captured in a low-resolution crystal structure. These structures combined with our previous success using prohead RNA–tRNA fusions demonstrates tRNA fusion is a powerful method in RNA structure determination.
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16
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Skeparnias I, Zhang J. Cooperativity and Interdependency between RNA Structure and RNA-RNA Interactions. Noncoding RNA 2021; 7:ncrna7040081. [PMID: 34940761 PMCID: PMC8704770 DOI: 10.3390/ncrna7040081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
Complex RNA–RNA interactions are increasingly known to play key roles in numerous biological processes from gene expression control to ribonucleoprotein granule formation. By contrast, the nature of these interactions and characteristics of their interfaces, especially those that involve partially or wholly structured RNAs, remain elusive. Herein, we discuss different modalities of RNA–RNA interactions with an emphasis on those that depend on secondary, tertiary, or quaternary structure. We dissect recently structurally elucidated RNA–RNA complexes including RNA triplexes, riboswitches, ribozymes, and reverse transcription complexes. These analyses highlight a reciprocal relationship that intimately links RNA structure formation with RNA–RNA interactions. The interactions not only shape and sculpt RNA structures but also are enabled and modulated by the structures they create. Understanding this two-way relationship between RNA structure and interactions provides mechanistic insights into the expanding repertoire of noncoding RNA functions, and may inform the design of novel therapeutics that target RNA structures or interactions.
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17
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Liu D, Shao Y, Piccirilli JA, Weizmann Y. Structures of artificially designed discrete RNA nanoarchitectures at near-atomic resolution. SCIENCE ADVANCES 2021; 7:eabf4459. [PMID: 34550747 PMCID: PMC8457670 DOI: 10.1126/sciadv.abf4459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 08/02/2021] [Indexed: 05/11/2023]
Abstract
Although advances in nanotechnology have enabled the construction of complex and functional synthetic nucleic acid–based nanoarchitectures, high-resolution discrete structures are lacking because of the difficulty in obtaining good diffracting crystals. Here, we report the design and construction of RNA nanostructures based on homooligomerizable one-stranded tiles for x-ray crystallographic determination. We solved three structures to near-atomic resolution: a 2D parallelogram, a 3D nanobracelet unexpectedly formed from an RNA designed for a nanocage, and, eventually, a bona fide 3D nanocage designed with the guidance of the two previous structures. Structural details of their constituent motifs, such as kissing loops, branched kissing loops, and T-junctions, that resemble natural RNA motifs and resisted x-ray determination are revealed, providing insights into those natural motifs. This work unveils the largely unexplored potential of crystallography in gaining high-resolution feedback for nanoarchitectural design and suggests a route to investigate RNA motif structures by configuring them into nanoarchitectures.
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Affiliation(s)
- Di Liu
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
| | - Yaming Shao
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Joseph A. Piccirilli
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Yossi Weizmann
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
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18
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Interplay between Host tRNAs and HIV-1: A Structural Perspective. Viruses 2021; 13:v13091819. [PMID: 34578400 PMCID: PMC8473020 DOI: 10.3390/v13091819] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/23/2022] Open
Abstract
The cellular metabolism of host tRNAs and life cycle of HIV-1 cross paths at several key virus-host interfaces. Emerging data suggest a multi-faceted interplay between host tRNAs and HIV-1 that plays essential roles, both structural and regulatory, in viral genome replication, genome packaging, and virion biogenesis. HIV-1 not only hijacks host tRNAs and transforms them into obligatory reverse transcription primers but further commandeers tRNAs to regulate the localization of its major structural protein, Gag, via a specific interface. This review highlights recent advances in understanding tRNA-HIV-1 interactions, primarily from a structural perspective, which start to elucidate their underlying molecular mechanisms, intrinsic specificities, and biological significances. Such understanding may provide new avenues toward developing HIV/AIDS treatments and therapeutics including small molecules and RNA biologics that target these host-virus interfaces.
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19
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Bou-Nader C, Muecksch F, Brown JB, Gordon JM, York A, Peng C, Ghirlando R, Summers MF, Bieniasz PD, Zhang J. HIV-1 matrix-tRNA complex structure reveals basis for host control of Gag localization. Cell Host Microbe 2021; 29:1421-1436.e7. [PMID: 34384537 PMCID: PMC8650744 DOI: 10.1016/j.chom.2021.07.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/24/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
The HIV-1 virion structural polyprotein, Gag, is directed to particle assembly sites at the plasma membrane by its N-terminal matrix (MA) domain. MA also binds to host tRNAs. To understand the molecular basis of MA-tRNA interaction and its potential function, we present a co-crystal structure of HIV-1 MA-tRNALys3 complex. The structure reveals a specialized group of MA basic and aromatic residues preconfigured to recognize the distinctive structure of the tRNA elbow. Mutational, cross-linking, fluorescence, and NMR analyses show that the crystallographically defined interface drives MA-tRNA binding in solution and living cells. The structure indicates that MA is unlikely to bind tRNA and membrane simultaneously. Accordingly, single-amino-acid substitutions that abolish MA-tRNA binding caused striking redistribution of Gag to the plasma membrane and reduced HIV-1 replication. Thus, HIV-1 exploits host tRNAs to occlude a membrane localization signal and control the subcellular distribution of its major structural protein.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Frauke Muecksch
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Jackson M Gordon
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Ashley York
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Chen Peng
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Michael F Summers
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
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20
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Townshend RJL, Eismann S, Watkins AM, Rangan R, Karelina M, Das R, Dror RO. Geometric deep learning of RNA structure. Science 2021; 373:1047-1051. [PMID: 34446608 PMCID: PMC9829186 DOI: 10.1126/science.abe5650] [Citation(s) in RCA: 155] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 07/14/2021] [Indexed: 01/28/2023]
Abstract
RNA molecules adopt three-dimensional structures that are critical to their function and of interest in drug discovery. Few RNA structures are known, however, and predicting them computationally has proven challenging. We introduce a machine learning approach that enables identification of accurate structural models without assumptions about their defining characteristics, despite being trained with only 18 known RNA structures. The resulting scoring function, the Atomic Rotationally Equivariant Scorer (ARES), substantially outperforms previous methods and consistently produces the best results in community-wide blind RNA structure prediction challenges. By learning effectively even from a small amount of data, our approach overcomes a major limitation of standard deep neural networks. Because it uses only atomic coordinates as inputs and incorporates no RNA-specific information, this approach is applicable to diverse problems in structural biology, chemistry, materials science, and beyond.
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Affiliation(s)
| | - Stephan Eismann
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Andrew M Watkins
- Department of Biochemistry, Stanford University, Stanford, CA, USA
| | - Ramya Rangan
- Department of Biochemistry, Stanford University, Stanford, CA, USA
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Masha Karelina
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University, Stanford, CA, USA.
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA.
- Department of Structural Biology, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
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21
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22
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Abstract
The crystallization and structural determination of large RNAs and their complexes remain major bottlenecks in the mechanistic analysis of cellular and viral RNAs. Here, we describe a protocol that combines postcrystallization dehydration and ion replacement that dramatically improved the diffraction quality of crystals of a large gene-regulatory tRNA-mRNA complex. Through this method, the resolution limit of X-ray data extended from 8.5 to 3.2 Å, enabling structure determination. Although this protocol was developed for a particular RNA complex, the general importance of solvent and counterions in nucleic acid structure may render it generally useful for crystallographic analysis of other RNAs.
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23
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Small-Molecule Antibiotics Inhibiting tRNA-Regulated Gene Expression Is a Viable Strategy for Targeting Gram-Positive Bacteria. Antimicrob Agents Chemother 2020; 65:AAC.01247-20. [PMID: 33077662 PMCID: PMC7927825 DOI: 10.1128/aac.01247-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/09/2020] [Indexed: 11/20/2022] Open
Abstract
Bacterial infections and the rise of antibiotic resistance, especially multidrug resistance, have generated a clear need for discovery of novel therapeutics. We demonstrated that a small-molecule drug, PKZ18, targets the T-box mechanism and inhibits bacterial growth. The T-box is a structurally conserved riboswitch-like gene regulator in the 5' untranslated region (UTR) of numerous essential genes of Gram-positive bacteria. T-boxes are stabilized by cognate, unacylated tRNA ligands, allowing the formation of an antiterminator hairpin in the mRNA that enables transcription of the gene. In the absence of an unacylated cognate tRNA, transcription is halted due to the formation of a thermodynamically more stable terminator hairpin. PKZ18 targets the site of the codon-anticodon interaction of the conserved stem I and reduces T-box-controlled gene expression. Here, we show that novel analogs of PKZ18 have improved MICs, bactericidal effects against methicillin-resistant Staphylococcus aureus (MRSA), and increased efficacy in nutrient-limiting conditions. The analogs have reduced cytotoxicity against eukaryotic cells compared to PKZ18. The PKZ18 analogs acted synergistically with aminoglycosides to significantly enhance the efficacy of the analogs and aminoglycosides, further increasing their therapeutic windows. RNA sequencing showed that the analog PKZ18-22 affects expression of 8 of 12 T-box controlled genes in a statistically significant manner, but not other 5'-UTR regulated genes in MRSA. Very low levels of resistance further support the existence of multiple T-box targets for PKZ18 analogs in the cell. Together, the multiple targets, low resistance, and synergy make PKZ18 analogs promising drugs for development and future clinical applications.
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24
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Zhang J. Unboxing the T-box riboswitches-A glimpse into multivalent and multimodal RNA-RNA interactions. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1600. [PMID: 32633085 PMCID: PMC7583486 DOI: 10.1002/wrna.1600] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/25/2020] [Accepted: 04/29/2020] [Indexed: 12/17/2022]
Abstract
The T-box riboswitches are widespread bacterial noncoding RNAs that directly bind specific tRNAs, sense aminoacylation on bound tRNAs, and switch conformations to control amino-acid metabolism and to maintain nutritional homeostasis. The core mechanisms of tRNA recognition, amino acid sensing, and conformational switching by the T-boxes have been recently elucidated, providing a wealth of new insights into multivalent and multimodal RNA-RNA interactions. This review dissects the structures and tRNA-recognition mechanisms by the Stem I, Stem II, and Discriminator domains, which collectively compose the T-box riboswitches. It further compares and contrasts the two classes of T-boxes that regulate transcription and translation, respectively, and integrates recent findings to derive general themes, trends, and insights into complex RNA-RNA interactions. Specifically, the T-box paradigm reveals that noncoding RNAs can interact with each other through multiple coordinated contacts, concatenation of stacked helices, and mutually induced fit. Numerous tertiary contacts, especially those emanating from strings of single-stranded purines, act in concert to reinforce long-range base-pairing and stacking interactions. These coordinated, mixed-mode contacts allow the T-box RNA to sterically sense aminoacylation on the tRNA using a bipartite steric sieve, and to couple this readout to a conformational switch mediated by tRNA-T-box stacking. Together, the insights gleaned from the T-box riboswitches inform investigations into other complex RNA structures and assemblies, development of T-box-targeted antimicrobials, and may inspire design and engineering of novel RNA sensors, regulators, and interfaces. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs Regulatory RNAs/RNAi/Riboswitches > Riboswitches.
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Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
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25
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Ishida S, Terasaka N, Katoh T, Suga H. An aminoacylation ribozyme evolved from a natural tRNA-sensing T-box riboswitch. Nat Chem Biol 2020; 16:702-709. [PMID: 32203413 DOI: 10.1038/s41589-020-0500-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 02/11/2020] [Indexed: 12/20/2022]
Abstract
When the primitive translation system first emerged in the hypothetical RNA world, ribozymes could have been responsible for aminoacylation. Given that naturally occurring T-box riboswitches selectively sense the aminoacylation status of cognate tRNAs, we introduced a domain of random sequence into a T-box-tRNA conjugate and isolated ribozymes that were self-aminoacylating on the 3'-terminal hydroxyl group. One of them, named Tx2.1, recognizes the anticodon and D-loop of tRNA via interaction with its stem I domain, similarly to the parental T-box, and selectively charges N-biotinyl-L-phenylalanine (Bio-lPhe) onto the 3' end of the cognate tRNA in trans. We also demonstrated the ribosomal synthesis of a Bio-lPhe-initiated peptide in a Tx2.1-coupled in vitro translation system, in which Tx2.1 catalyzed specific tRNA aminoacylation in situ. This suggests that such ribozymes could have coevolved with a primitive translation system in the RNA world.
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Affiliation(s)
- Satoshi Ishida
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Naohiro Terasaka
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Takayuki Katoh
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
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26
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27
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Suddala KC, Zhang J. High-affinity recognition of specific tRNAs by an mRNA anticodon-binding groove. Nat Struct Mol Biol 2019; 26:1114-1122. [PMID: 31792448 PMCID: PMC6903423 DOI: 10.1038/s41594-019-0335-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/21/2019] [Indexed: 11/10/2022]
Abstract
T-box riboswitches are modular bacterial noncoding RNAs that sense and regulate amino acid availability through direct interactions with tRNAs. Between the 5' anticodon-binding stem I domain and the 3' amino acid sensing domains of most T-boxes lies the stem II domain of unknown structure and function. Here, we report a 2.8-Å cocrystal structure of the Nocardia farcinica ileS T-box in complex with its cognate tRNAIle. The structure reveals a perpendicularly arranged ultrashort stem I containing a K-turn and an elongated stem II bearing an S-turn. Both stems rest against a compact pseudoknot, dock via an extended ribose zipper and jointly create a binding groove specific to the anticodon of its cognate tRNA. Contrary to proposed distal contacts to the tRNA elbow region, stem II locally reinforces the codon-anticodon interactions between stem I and tRNA, achieving low-nanomolar affinity. This study illustrates how mRNA junctions can create specific binding sites for interacting RNAs of prescribed sequence and structure.
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Affiliation(s)
- Krishna C Suddala
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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28
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Li S, Su Z, Lehmann J, Stamatopoulou V, Giarimoglou N, Henderson FE, Fan L, Pintilie GD, Zhang K, Chen M, Ludtke SJ, Wang YX, Stathopoulos C, Chiu W, Zhang J. Structural basis of amino acid surveillance by higher-order tRNA-mRNA interactions. Nat Struct Mol Biol 2019; 26:1094-1105. [PMID: 31740854 PMCID: PMC6899168 DOI: 10.1038/s41594-019-0326-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/07/2019] [Indexed: 12/11/2022]
Abstract
Amino acid availability in Gram-positive bacteria is monitored by T-box riboswitches. T-boxes directly bind tRNAs, assess their aminoacylation state, and regulate the transcription or translation of downstream genes to maintain nutritional homeostasis. Here, we report cocrystal and cryo-EM structures of Geobacillus kaustophilus and Bacillus subtilis T-box-tRNA complexes, detailing their multivalent, exquisitely selective interactions. The T-box forms a U-shaped molecular vise that clamps the tRNA, captures its 3' end using an elaborate 'discriminator' structure, and interrogates its aminoacylation state using a steric filter fashioned from a wobble base pair. In the absence of aminoacylation, T-boxes clutch tRNAs and form a continuously stacked central spine, permitting transcriptional readthrough or translation initiation. A modeled aminoacyl disrupts tRNA-T-box stacking, severing the central spine and blocking gene expression. Our data establish a universal mechanism of amino acid sensing on tRNAs and gene regulation by T-box riboswitches and exemplify how higher-order RNA-RNA interactions achieve multivalency and specificity.
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Affiliation(s)
- Shuang Li
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Zhaoming Su
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Jean Lehmann
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Campus Paris-Saclay, Gif-sur-Yvette, France
| | | | - Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, Patras, Greece
| | - Frances E Henderson
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Lixin Fan
- Small-Angle X-ray Scattering Core Facility, Center for Cancer Research of the National Cancer Institute, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc, Frederick, MD, USA
| | - Grigore D Pintilie
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Kaiming Zhang
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Muyuan Chen
- Verna Marrs and McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Steven J Ludtke
- Verna Marrs and McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Yun-Xing Wang
- Small-Angle X-ray Scattering Core Facility, Center for Cancer Research of the National Cancer Institute, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc, Frederick, MD, USA.,Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | | | - Wah Chiu
- Department of Bioengineering and Department of Microbiology and Immunology, James H. Clark Center, Stanford University, Stanford, CA, USA. .,Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, Stanford University, Stanford, CA, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA.
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29
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Battaglia RA, Grigg JC, Ke A. Structural basis for tRNA decoding and aminoacylation sensing by T-box riboregulators. Nat Struct Mol Biol 2019; 26:1106-1113. [PMID: 31740853 PMCID: PMC6953718 DOI: 10.1038/s41594-019-0327-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 10/07/2019] [Indexed: 01/31/2023]
Abstract
T-box riboregulators are a class of cis-regulatory RNAs that govern the bacterial response to amino acid starvation by binding, decoding and reading the aminoacylation status of specific transfer RNAs. Here we provide a high-resolution crystal structure of a full-length T-box from Mycobacterium tuberculosis that explains tRNA decoding and aminoacylation sensing by this riboregulator. Overall, the T-box consists of decoding and aminoacylation sensing modules bridged by a rigid pseudoknot structure formed by the mid-region domains. Stem-I and the Stem-II S-turn assemble a claw-like decoding module, while the antiterminator, Stem-III, and the adjacent linker form a tightly interwoven aminoacylation sensing module. The uncharged tRNA is selectively recognized by an unexpected set of favorable contacts from the linker region in the aminoacylation sensing module. A complex structure with a charged tRNA mimic shows that the extra moiety dislodges the linker, which is indicative of the possible chain of events that lead to alternative base-pairing and altered expression output.
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Affiliation(s)
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Ithaca, NY, USA.
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30
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Regulation of Bacterial Gene Expression by Transcription Attenuation. Microbiol Mol Biol Rev 2019; 83:83/3/e00019-19. [PMID: 31270135 DOI: 10.1128/mmbr.00019-19] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A wide variety of mechanisms that control gene expression in bacteria are based on conditional transcription termination. Generally, in these mechanisms, a transcription terminator is located between a promoter and a downstream gene(s), and the efficiency of the terminator is controlled by a regulatory effector that can be a metabolite, protein, or RNA. The most common type of regulation involving conditional termination is transcription attenuation, in which the primary regulatory target is an essential element of a single terminator. The terminator can be either intrinsic or Rho dependent, with each presenting unique regulatory targets. Transcription attenuation mechanisms can be divided into five classes based primarily on the manner in which transcription termination is rendered conditional. This review summarizes each class of control mechanisms from a historical perspective, describes important examples in a physiological context and the current state of knowledge, highlights major advances, and discusses expectations of future discoveries.
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Suddala KC, Zhang J. An evolving tale of two interacting RNAs-themes and variations of the T-box riboswitch mechanism. IUBMB Life 2019; 71:1167-1180. [PMID: 31206978 DOI: 10.1002/iub.2098] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 05/10/2019] [Indexed: 01/10/2023]
Abstract
T-box riboswitches are a widespread class of structured noncoding RNAs in Gram-positive bacteria that regulate the expression of amino acid-related genes. They form negative feedback loops to maintain steady supplies of aminoacyl-transfer RNAs (tRNAs) to the translating ribosomes. T-box riboswitches are located in the 5' leader regions of mRNAs that they regulate and directly bind to their cognate tRNA ligands. T-boxes further sense the aminoacylation state of the bound tRNAs and, based on this readout, regulate gene expression at the level of transcription or translation. T-box riboswitches consist of two conserved domains-a 5' Stem I domain that is involved in specific tRNA recognition and a 3' antiterminator/antisequestrator (or discriminator) domain that senses the amino acid on the 3' end of the bound tRNA. Interaction of the 3' end of an uncharged but not charged tRNA with a thermodynamically weak discriminator domain stabilizes it to promote transcription readthrough or translation initiation. Recent biochemical, biophysical, and structural studies have provided high-resolution insights into the mechanism of tRNA recognition by Stem I, several structural models of full-length T-box-tRNA complexes, mechanism of amino acid sensing by the antiterminator domain, as well as kinetic details of tRNA binding to the T-box riboswitches. In addition, translation-regulating T-box riboswitches have been recently characterized, which presented key differences from the canonical transcriptional T-boxes. Here, we review the recent developments in understanding the T-box riboswitch mechanism that have employed various complementary approaches. Further, the regulation of multiple essential genes by T-boxes makes them very attractive drug targets to combat drug resistance. The recent progress in understanding the biochemical, structural, and dynamic aspects of the T-box riboswitch mechanism will enable more precise and effective targeting with small molecules. © 2019 IUBMB Life, 2019 © 2019 IUBMB Life, 71(8):1167-1180, 2019.
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Affiliation(s)
- Krishna C Suddala
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Abstract
The T-box riboswitch is a unique, RNA-based regulatory mechanism that modulates expression of a wide variety of amino acid-related genes, predominantly in Firmicutes. RNAs of this class selectively bind a specific cognate tRNA, utilizing recognition of the tRNA anticodon and other tRNA features. The riboswitch monitors the aminoacylation status of the tRNA to induce expression of the regulated downstream gene(s) at the level of transcription antitermination or derepression of translation initiation in response to reduced tRNA charging via stabilization of an antiterminator or antisequestrator. Recent biochemical and structural studies have revealed new features of tRNA recognition that extend beyond the initially identified Watson-Crick base-pairing of a codon-like sequence in the riboswitch with the tRNA anticodon, and residues in the antiterminator or antisequestrator with the tRNA acceptor end. These studies have revealed new tRNA contacts and new modes of riboswitch function and ligand recognition that expand our understanding of RNA-RNA recognition and the biological roles of tRNA.
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Ray S, Chauvier A, Walter NG. Kinetics coming into focus: single-molecule microscopy of riboswitch dynamics. RNA Biol 2018; 16:1077-1085. [PMID: 30328748 DOI: 10.1080/15476286.2018.1536594] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Riboswitches are dynamic RNA motifs that are mostly embedded in the 5'-untranslated regions of bacterial mRNAs, where they regulate gene expression transcriptionally or translationally by undergoing conformational changes upon binding of a small metabolite or ion. Due to the small size of typical ligands, relatively little free energy is available from ligand binding to overcome the often high energetic barrier of reshaping RNA structure. Instead, most riboswitches appear to take advantage of the directional and hierarchical folding of RNA by employing the ligand as a structural 'linchpin' to adjust the kinetic partitioning between alternate folds. In this model, even small, local structural and kinetic effects of ligand binding can cascade into global RNA conformational changes affecting gene expression. Single-molecule (SM) microscopy tools are uniquely suited to study such kinetically controlled RNA folding since they avoid the ensemble averaging of bulk techniques that loses sight of unsynchronized, transient, and/or multi-state kinetic behavior. This review summarizes how SM methods have begun to unravel riboswitch-mediated gene regulation.
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Affiliation(s)
- Sujay Ray
- a Single Molecule Analysis Group, Department of Chemistry, University of Michigan , Ann Arbor , MI , USA
| | - Adrien Chauvier
- a Single Molecule Analysis Group, Department of Chemistry, University of Michigan , Ann Arbor , MI , USA
| | - Nils G Walter
- a Single Molecule Analysis Group, Department of Chemistry, University of Michigan , Ann Arbor , MI , USA
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Zhang J, Chetnani B, Cormack ED, Alonso D, Liu W, Mondragón A, Fei J. Specific structural elements of the T-box riboswitch drive the two-step binding of the tRNA ligand. eLife 2018; 7:39518. [PMID: 30251626 PMCID: PMC6197855 DOI: 10.7554/elife.39518] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/24/2018] [Indexed: 12/29/2022] Open
Abstract
T-box riboswitches are cis-regulatory RNA elements that regulate the expression of proteins involved in amino acid biosynthesis and transport by binding to specific tRNAs and sensing their aminoacylation state. While the T-box modular structural elements that recognize different parts of a tRNA have been identified, the kinetic trajectory describing how these interactions are established temporally remains unclear. Using smFRET, we demonstrate that tRNA binds to the riboswitch in two steps, first anticodon recognition followed by the sensing of the 3’ NCCA end, with the second step accompanied by a T-box riboswitch conformational change. Studies on site-specific mutants highlight that specific T-box structural elements drive the two-step binding process in a modular fashion. Our results set up a kinetic framework describing tRNA binding by T-box riboswitches, and suggest such binding mechanism is kinetically beneficial for efficient, co-transcriptional recognition of the cognate tRNA ligand. Living organisms depend upon a group of chemicals called amino acids to survive. Amino acids are the building blocks of proteins, and proteins have many important roles within and around cells. Bacteria regulate certain genes to ensure they have the right balance of different amino acids to survive. By controlling the availability of certain proteins that help them to make or collect certain amino acids, bacteria can control their overall amino acid balance. Before a protein is made, a molecular machine called RNA polymerase must first copy the information in a gene to make a molecule called a messenger RNA (mRNA). The mRNA is then translated to make the protein from individual amino acids. In this process, each amino acid needs to be first attached to another molecule called a transfer RNA (tRNA). In many bacteria species, the mRNAs involved in making or transporting amino acids contain structures called T-boxes. These structures guide the RNA polymerase to make more of the mRNAs when the levels of the amino acid become too low. A T-box, however, does not sense the level of the amino acid directly. Instead it senses the number of tRNA molecules that do not carry an amino acid. Zhang, Chetnani et al. examined a particular T-box interacting with tRNA using pairs of fluorescent dyes to detect distances between molecules. The T-box first recognizes a part of the tRNA called the anticodon to make sure it binds the correct type of tRNA. It then changes its shape to detect whether the tRNA is attached to an amino acid. This two-step process is driven by multiple structural elements within the T-box, and the flexibility of the T-box plays a critical role. A cell’s survival depends on it keeping amino acid levels under control. Understanding how bacteria do this could lead to new antibiotic drugs that target the T-box to kill cells. This study also provides insights into the workings of mRNA components like T-boxes – a type of riboswitch – which is an unusual means of controlling gene activity.
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Affiliation(s)
- Jiacheng Zhang
- Institute for Biophysical Dynamics, University of Chicago, Chicago, United States
| | - Bhaskar Chetnani
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | | | - Dulce Alonso
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Wei Liu
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Alfonso Mondragón
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Jingyi Fei
- Institute for Biophysical Dynamics, University of Chicago, Chicago, United States.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
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Hierarchical mechanism of amino acid sensing by the T-box riboswitch. Nat Commun 2018; 9:1896. [PMID: 29760498 PMCID: PMC5951919 DOI: 10.1038/s41467-018-04305-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 04/16/2018] [Indexed: 11/08/2022] Open
Abstract
In Gram-positive bacteria, T-box riboswitches control gene expression to maintain the cellular pools of aminoacylated tRNAs essential for protein biosynthesis. Co-transcriptional binding of an uncharged tRNA to the riboswitch stabilizes an antiterminator, allowing transcription read-through, whereas an aminoacylated tRNA does not. Recent structural studies have resolved two contact points between tRNA and Stem-I in the 5' half of the T-box riboswitch, but little is known about the mechanism empowering transcriptional control by a small, distal aminoacyl modification. Using single-molecule fluorescence microscopy, we have probed the kinetic and structural underpinnings of tRNA binding to a glycyl T-box riboswitch. We observe a two-step mechanism where fast, dynamic recruitment of tRNA by Stem-I is followed by ultra-stable anchoring by the downstream antiterminator, but only without aminoacylation. Our results support a hierarchical sensing mechanism wherein dynamic global binding of the tRNA body is followed by localized readout of its aminoacylation status by snap-lock-based trapping.
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36
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New tRNA contacts facilitate ligand binding in a Mycobacterium smegmatis T box riboswitch. Proc Natl Acad Sci U S A 2018; 115:3894-3899. [PMID: 29581302 DOI: 10.1073/pnas.1721254115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
T box riboswitches are RNA regulatory elements widely used by organisms in the phyla Firmicutes and Actinobacteria to regulate expression of amino acid-related genes. Expression of T box family genes is down-regulated by transcription attenuation or inhibition of translation initiation in response to increased charging of the cognate tRNA. Three direct contacts with tRNA have been described; however, one of these contacts is absent in a subclass of T box RNAs and the roles of several structural domains conserved in most T box RNAs are unknown. In this study, structural elements of a Mycobacterium smegmatis ileS T box riboswitch variant with an Ultrashort (US) Stem I were sequentially deleted, which resulted in a progressive decrease in binding affinity for the tRNAIle ligand. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) revealed structural changes in conserved riboswitch domains upon interaction with the tRNA ligand. Cross-linking and mutational analyses identified two interaction sites, one between the S-turn element in Stem II and the T arm of tRNAIle and the other between the Stem IIA/B pseudoknot and the D loop of tRNAIle These newly identified RNA contacts add information about tRNA recognition by the T box riboswitch and demonstrate a role for the S-turn and pseudoknot elements, which resemble structural elements that are common in many cellular RNAs.
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37
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Stamatopoulou V, Apostolidi M, Li S, Lamprinou K, Papakyriakou A, Zhang J, Stathopoulos C. Direct modulation of T-box riboswitch-controlled transcription by protein synthesis inhibitors. Nucleic Acids Res 2017; 45:10242-10258. [PMID: 28973457 PMCID: PMC5622331 DOI: 10.1093/nar/gkx663] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/18/2017] [Indexed: 11/14/2022] Open
Abstract
Recently, it was discovered that exposure to mainstream antibiotics activate numerous bacterial riboregulators that control antibiotic resistance genes including metabolite-binding riboswitches and other transcription attenuators. However, the effects of commonly used antibiotics, many of which exhibit RNA-binding properties, on the widespread T-box riboswitches, remain unknown. In Staphylococcus aureus, a species-specific glyS T-box controls the supply of glycine for both ribosomal translation and cell wall synthesis, making it a promising target for next-generation antimicrobials. Here, we report that specific protein synthesis inhibitors could either significantly increase T-box-mediated transcription antitermination, while other compounds could suppress it, both in vitro and in vivo. In-line probing of the full-length T-box combined with molecular modelling and docking analyses suggest that the antibiotics that promote transcription antitermination stabilize the T-box:tRNA complex through binding specific positions on stem I and the Staphylococcal-specific stem Sa. By contrast, the antibiotics that attenuate T-box transcription bind to other positions on stem I and do not interact with stem Sa. Taken together, our results reveal that the transcription of essential genes controlled by T-box riboswitches can be directly modulated by commonly used protein synthesis inhibitors. These findings accentuate the regulatory complexities of bacterial response to antimicrobials that involve multiple riboregulators.
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Affiliation(s)
| | - Maria Apostolidi
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Shuang Li
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, 50 South Drive, Bethesda, MD 20892, USA
| | - Katerina Lamprinou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Athanasios Papakyriakou
- Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos', Athens, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, 50 South Drive, Bethesda, MD 20892, USA
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38
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Growth-Rate Dependent Regulation of tRNA Level and Charging in Bacillus licheniformis. J Mol Biol 2017; 429:3102-3112. [DOI: 10.1016/j.jmb.2017.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/09/2017] [Accepted: 09/09/2017] [Indexed: 11/21/2022]
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39
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Chetnani B, Mondragón A. Molecular envelope and atomic model of an anti-terminated glyQS T-box regulator in complex with tRNAGly. Nucleic Acids Res 2017; 45:8079-8090. [PMID: 28531275 PMCID: PMC5570125 DOI: 10.1093/nar/gkx451] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/03/2017] [Accepted: 05/08/2017] [Indexed: 11/26/2022] Open
Abstract
A T-box regulator or riboswitch actively monitors the levels of charged/uncharged tRNA and participates in amino acid homeostasis by regulating genes involved in their utilization or biosynthesis. It has an aptamer domain for cognate tRNA recognition and an expression platform to sense the charge state and modulate gene expression. These two conserved domains are connected by a variable linker that harbors additional secondary structural elements, such as Stem III. The structural basis for specific tRNA binding is known, but the structural basis for charge sensing and the role of other elements remains elusive. To gain new structural insights on the T-box mechanism, a molecular envelope was calculated from small angle X-ray scattering data for the Bacillus subtilis glyQS T-box riboswitch in complex with an uncharged tRNAGly. A structural model of an anti-terminated glyQS T-box in complex with its cognate tRNAGly was derived based on the molecular envelope. It shows the location and relative orientation of various secondary structural elements. The model was validated by comparing the envelopes of the wild-type complex and two variants. The structural model suggests that in addition to a possible regulatory role, Stem III could aid in preferential stabilization of the T-box anti-terminated state allowing read-through of regulated genes.
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MESH Headings
- Bacillus subtilis/genetics
- Bacillus subtilis/metabolism
- Base Sequence
- Models, Molecular
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer, Gly/chemistry
- RNA, Transfer, Gly/genetics
- RNA, Transfer, Gly/metabolism
- Riboswitch/genetics
- Scattering, Small Angle
- X-Ray Diffraction
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Affiliation(s)
- Bhaskar Chetnani
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA
| | - Alfonso Mondragón
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA
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40
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Sherwood AV, Henkin TM. Riboswitch-Mediated Gene Regulation: Novel RNA Architectures Dictate Gene Expression Responses. Annu Rev Microbiol 2017; 70:361-74. [PMID: 27607554 DOI: 10.1146/annurev-micro-091014-104306] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Riboswitches are RNA elements that act on the mRNA with which they are cotranscribed to modulate expression of that mRNA. These elements are widely found in bacteria, where they have a broad impact on gene expression. The defining feature of riboswitches is that they directly recognize a physiological signal, and the resulting shift in RNA structure affects gene regulation. The majority of riboswitches respond to cellular metabolites, often in a feedback loop to repress synthesis of the enzymes used to produce the metabolite. Related elements respond to the aminoacylation status of a specific tRNA or to a physical parameter, such as temperature or pH. Recent studies have identified new classes of riboswitches and have revealed new insights into the molecular mechanisms of signal recognition and gene regulation. Application of structural and biophysical approaches has complemented previous genetic and biochemical studies, yielding new information about how different riboswitches operate.
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Affiliation(s)
- Anna V Sherwood
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210; .,Molecular, Cellular and Developmental Graduate Program, The Ohio State University, Columbus, Ohio 43210
| | - Tina M Henkin
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210;
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41
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Zhang J, Ferré-DAmaré AR. Trying on tRNA for Size: RNase P and the T-box Riboswitch as Molecular Rulers. Biomolecules 2016; 6:biom6020018. [PMID: 27043647 PMCID: PMC4919913 DOI: 10.3390/biom6020018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 03/23/2016] [Accepted: 03/25/2016] [Indexed: 12/27/2022] Open
Abstract
Length determination is a fundamental problem in biology and chemistry. Numerous proteins measure distances on linear biopolymers to exert effects with remarkable spatial precision. Recently, ruler-like devices made of noncoding RNAs have been structurally and biochemically characterized. Two prominent examples are the RNase P ribozyme and the T-box riboswitch. Both act as molecular calipers. The two RNAs clamp onto the elbow of tRNA (or pre-tRNA) and make distance measurements orthogonal to each other. Here, we compare and contrast the molecular ruler characteristics of these RNAs. RNase P appears pre-configured to measure a fixed distance on pre-tRNA to ensure the fidelity of its maturation. RNase P is a multiple-turnover ribozyme, and its rigid structure efficiently selects pre-tRNAs, cleaves, and releases them. In contrast, the T-box is flexible and segmented, an architecture that adapts to the intrinsically flexible tRNA. The tripartite T-box inspects the overall shape, anticodon sequence, and aminoacylation status of an incoming tRNA while it folds co-transcriptionally, leading to a singular, conditional genetic switching event. The elucidation of the structures and mechanisms of action of these two RNA molecular rulers may augur the discovery of new RNA measuring devices in noncoding and viral transcriptomes, and inform the design of artificial RNA rulers.
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Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, 50 South Drive, Bethesda, MD 20892, USA.
| | - Adrian R Ferré-DAmaré
- Laboratory of RNA Biophysics and Cellular Physiology, National Heart, Lung and Blood Institute, 50 South Drive, Bethesda, MD 20892, USA.
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42
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Zhang J, Ferré-D'Amaré AR. Post-crystallization Improvement of RNA Crystal Diffraction Quality. Methods Mol Biol 2016; 1316:13-24. [PMID: 25967049 DOI: 10.1007/978-1-4939-2730-2_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The crystallization and structural determination of large RNAs and their complexes remain major bottlenecks in the mechanistic analysis of cellular and viral RNAs. Here, we describe a protocol that combines post-crystallization dehydration and ion replacement that dramatically improved the diffraction quality of crystals of a large gene-regulatory tRNA-mRNA complex. Through this method, the resolution limit of X-ray data extended from 8.5 to 3.2 Å, enabling structure determination. Although this protocol was developed for a particular RNA complex, the general importance of solvent and counterions in nucleic acid structure may render it generally useful for crystallographic analysis of other RNAs.
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Affiliation(s)
- Jinwei Zhang
- National Heart, Lung and Blood Institute, 50 South Drive, MSC 8012, Bethesda, MD, 20892-8012, USA
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43
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Zhang J, Landick R. A Two-Way Street: Regulatory Interplay between RNA Polymerase and Nascent RNA Structure. Trends Biochem Sci 2016; 41:293-310. [PMID: 26822487 DOI: 10.1016/j.tibs.2015.12.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 02/06/2023]
Abstract
The vectorial (5'-to-3' at varying velocity) synthesis of RNA by cellular RNA polymerases (RNAPs) creates a rugged kinetic landscape, demarcated by frequent, sometimes long-lived, pauses. In addition to myriad gene-regulatory roles, these pauses temporally and spatially program the co-transcriptional, hierarchical folding of biologically active RNAs. Conversely, these RNA structures, which form inside or near the RNA exit channel, interact with the polymerase and adjacent protein factors to influence RNA synthesis by modulating pausing, termination, antitermination, and slippage. Here, we review the evolutionary origin, mechanistic underpinnings, and regulatory consequences of this interplay between RNAP and nascent RNA structure. We categorize and rationalize the extensive linkage between the transcriptional machinery and its product, and provide a framework for future studies.
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Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
| | - Robert Landick
- Departments of Biochemistry and Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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44
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The tRNA Elbow in Structure, Recognition and Evolution. Life (Basel) 2016; 6:life6010003. [PMID: 26771646 PMCID: PMC4810234 DOI: 10.3390/life6010003] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/04/2016] [Accepted: 01/06/2016] [Indexed: 01/07/2023] Open
Abstract
Prominent in the L-shaped three-dimensional structure of tRNAs is the "elbow" where their two orthogonal helical stacks meet. It has a conserved structure arising from the interaction of the terminal loops of the D- and T-stem-loops, and presents to solution a flat face of a tertiary base pair between the D- and T-loops. In addition to the ribosome, which interacts with the elbow in all three of its tRNA binding sites, several cellular RNAs and many proteins are known to recognize the elbow. At least three classes of non-coding RNAs, namely 23S rRNA, ribonuclease P, and the T-box riboswitches, recognize the tRNA elbow employing an identical structural motif consisting of two interdigitated T-loops. In contrast, structural solutions to tRNA-elbow recognition by proteins are varied. Some enzymes responsible for post-transcriptional tRNA modification even disrupt the elbow structure in order to access their substrate nucleotides. The evolutionary origin of the elbow is mysterious, but, because it does not explicitly participate in the flow of genetic information, it has been proposed to be a late innovation. Regardless, it is biologically essential. Even some viruses that hijack the cellular machinery using tRNA decoys have convergently evolved near-perfect mimics of the tRNA elbow.
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45
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Liu J, Zeng C, Hogan V, Zhou S, Monwar MM, Hines JV. Identification of Spermidine Binding Site in T-box Riboswitch Antiterminator RNA. Chem Biol Drug Des 2015; 87:182-9. [PMID: 26348362 DOI: 10.1111/cbdd.12660] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/24/2015] [Accepted: 08/14/2015] [Indexed: 01/08/2023]
Abstract
The T-box transcription antitermination riboswitch controls bacterial gene expression by structurally responding to uncharged, cognate tRNA. Previous studies indicated that cofactors, such as the polyamine spermidine, might serve a specific functional role in enhancing riboswitch efficacy. As riboswitch function depends on key RNA structural changes involving the antiterminator element, the interaction of spermidine with the T-box riboswitch antiterminator element was investigated. Spermidine binds antiterminator model RNA with high affinity (micromolar Kd ) based on isothermal titration calorimetry and fluorescence-monitored binding assays. NMR titration studies, molecular modeling, and inline and enzymatic probing studies indicate that spermidine binds at the 3' portion of the highly conserved seven-nucleotide bulge in the antiterminator. Together, these results support the conclusion that spermidine binds the T-box antiterminator RNA preferentially in a location important for antiterminator function. The implications of these findings are significant both for better understanding of the T-box riboswitch mechanism and for antiterminator-targeted drug discovery efforts.
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Affiliation(s)
- Jia Liu
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
| | - Chunxi Zeng
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
| | - Vivian Hogan
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
| | - Shu Zhou
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
| | - Md Masud Monwar
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
| | - Jennifer V Hines
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
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46
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Apostolidi M, Saad NY, Drainas D, Pournaras S, Becker HD, Stathopoulos C. A glyS T-box riboswitch with species-specific structural features responding to both proteinogenic and nonproteinogenic tRNAGly isoacceptors. RNA (NEW YORK, N.Y.) 2015; 21:1790-806. [PMID: 26276802 PMCID: PMC4574755 DOI: 10.1261/rna.052712.115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 07/13/2015] [Indexed: 06/04/2023]
Abstract
In Staphylococcus aureus, a T-box riboswitch exists upstream of the glyS gene to regulate transcription of the sole glycyl-tRNA synthetase, which aminoacylates five tRNA(Gly) isoacceptors bearing GCC or UCC anticodons. Subsequently, the glycylated tRNAs serve as substrates for decoding glycine codons during translation, and also as glycine donors for exoribosomal synthesis of pentaglycine peptides during cell wall formation. Probing of the predicted T-box structure revealed a long stem I, lacking features previously described for similar T-boxes. Moreover, the antiterminator stem includes a 42-nt long intervening sequence, which is staphylococci-specific. Finally, the terminator conformation adopts a rigid two-stem structure, where the intervening sequence forms the first stem followed by the second stem, which includes the more conserved residues. Interestingly, all five tRNA(Gly) isoacceptors interact with S. aureus glyS T-box with different binding affinities and they all induce transcription readthrough at different levels. The ability of both GCC and UCC anticodons to interact with the specifier loop indicates ambiguity during the specifier triplet reading, similar to the unconventional reading of glycine codons during protein synthesis. The S. aureus glyS T-box structure is consistent with the recent crystallographic and NMR studies, despite apparent differences, and highlights the phylogenetic variability of T-boxes when studied in a genome-dependent context. Our data suggest that the S. aureus glyS T-box exhibits differential tRNA selectivity, which possibly contributes toward the regulation and synchronization of ribosomal and exoribosomal peptide synthesis, two essential but metabolically unrelated pathways.
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Affiliation(s)
- Maria Apostolidi
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Nizar Y Saad
- Unité Mixte de Recherche 7156 Génétique Moléculaire, Génomique, Microbiologie, CNRS, Université de Strasbourg, F-67084 Strasbourg, France
| | - Denis Drainas
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Spyros Pournaras
- Department of Microbiology, School of Medicine, University of Athens, 11527 Athens, Greece
| | - Hubert D Becker
- Unité Mixte de Recherche 7156 Génétique Moléculaire, Génomique, Microbiologie, CNRS, Université de Strasbourg, F-67084 Strasbourg, France
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Zhang J, Ferré-D'Amaré AR. Dramatic improvement of crystals of large RNAs by cation replacement and dehydration. Structure 2015; 22:1363-1371. [PMID: 25185828 DOI: 10.1016/j.str.2014.07.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/11/2014] [Accepted: 07/28/2014] [Indexed: 12/21/2022]
Abstract
Compared to globular proteins, RNAs with complex 3D folds are characterized by poorly differentiated molecular surfaces dominated by backbone phosphates, sparse tertiary contacts stabilizing global architecture, and conformational flexibility. The resulting generally poor order of crystals of large RNAs and their complexes frequently hampers crystallographic structure determination. We describe and rationalize a postcrystallization treatment strategy that exploits the importance of solvation and counterions for RNA folding. Replacement of Li(+) and Mg(2+) needed for growth of crystals of a tRNA-riboswitch-protein complex with Sr(2+), coupled with dehydration, dramatically improved the resolution limit (8.5-3.2 Å) and data quality, enabling structure determination. The soft Sr(2+) ion forms numerous stabilizing intermolecular contacts. Comparison of pre- and posttreatment structures reveals how RNA assemblies redistribute as quasi-rigid bodies to yield improved crystal packing. Cation exchange complements previously reported postcrystallization dehydration of protein crystals and represents a potentially general strategy for improving crystals of large RNAs.
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Affiliation(s)
- Jinwei Zhang
- National Heart, Lung and Blood Institute, 50 South Drive, MSC 8012, Bethesda, MD 20892-8012, USA
| | - Adrian R Ferré-D'Amaré
- National Heart, Lung and Blood Institute, 50 South Drive, MSC 8012, Bethesda, MD 20892-8012, USA.
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Zhang J, Ferré-D'Amaré AR. Structure and mechanism of the T-box riboswitches. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 6:419-33. [PMID: 25959893 DOI: 10.1002/wrna.1285] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/19/2015] [Accepted: 03/25/2015] [Indexed: 01/11/2023]
Abstract
In most Gram-positive bacteria, including many clinically devastating pathogens from genera such as Bacillus, Clostridium, Listeria, and Staphylococcus, T-box riboswitches sense and regulate intracellular availability of amino acids through a multipartite messenger RNA (mRNA)-transfer RNA (tRNA) interaction. The T-box mRNA leaders respond to nutrient starvation by specifically binding cognate tRNAs and sensing whether the bound tRNA is aminoacylated, as a proxy for amino acid availability. Based on this readout, T-boxes direct a transcriptional or translational switch to control the expression of downstream genes involved in various aspects of amino acid metabolism: biosynthesis, transport, aminoacylation, transamidation, and so forth. Two decades after its discovery, the structural and mechanistic underpinnings of the T-box riboswitch were recently elucidated, producing a wealth of insights into how two structured RNAs can recognize each other with robust affinity and exquisite selectivity. The T-box paradigm exemplifies how natural noncoding RNAs can interact not just through sequence complementarity but can add molecular specificity by precisely juxtaposing RNA structural motifs, exploiting inherently flexible elements and the biophysical properties of post-transcriptional modifications, ultimately achieving a high degree of shape complementarity through mutually induced fit. The T-box also provides a proof-of-principle that compact RNA domains can recognize minute chemical changes (such as tRNA aminoacylation) on another RNA. The unveiling of the structure and mechanism of the T-box system thus expands our appreciation of the range of capabilities and modes of action of structured noncoding RNAs, and hints at the existence of networks of noncoding RNAs that communicate through both, structural and sequence specificity.
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Affiliation(s)
- Jinwei Zhang
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
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Zhang J, Ferré-D'Amaré AR. A flexible, scalable method for preparation of homogeneous aminoacylated tRNAs. Methods Enzymol 2014; 549:105-13. [PMID: 25432746 DOI: 10.1016/b978-0-12-801122-5.00005-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transfer RNAs (tRNAs) are cellular courier molecules that decipher the genetic code in messenger RNAs and enable the transfer of appropriate esterified amino acids to the growing peptide chain. The preparation of biophysical quantities of homogeneous aminoacylated tRNAs has remained a significant technical challenge. This is primarily due to the difficulty in removing contaminating nonaminoacylated tRNAs that are have very similar properties overall, as well as the hydrolytic instability of the aminoacyl linkage. We describe a flexible, scalable method to prepare homogeneous aminoacylated tRNAs that is also broadly compatible with mutant, misacylated, or otherwise aberrant tRNAs and other RNAs. This method combines ribozyme-mediated aminoacylation with reversible N-pentenoylation of the esterified amino acid, which not only protects against spontaneous deacylation but also provides a hydrophobic purification handle. This protocol makes it straightforward to produce biophysical quantities of natural and unnatural aminoacylated tRNAs and has proven essential for mechanistic investigations of the T-box riboswitches.
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Affiliation(s)
- Jinwei Zhang
- National Heart, Lung and Blood Institute, Bethesda, Maryland, USA
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