101
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Peck SA, Hughes KD, Victorino JF, Mosley AL. Writing a wrong: Coupled RNA polymerase II transcription and RNA quality control. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1529. [PMID: 30848101 PMCID: PMC6570551 DOI: 10.1002/wrna.1529] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 12/27/2018] [Accepted: 02/07/2019] [Indexed: 12/20/2022]
Abstract
Processing and maturation of precursor RNA species is coupled to RNA polymerase II transcription. Co-transcriptional RNA processing helps to ensure efficient and proper capping, splicing, and 3' end processing of different RNA species to help ensure quality control of the transcriptome. Many improperly processed transcripts are not exported from the nucleus, are restricted to the site of transcription, and are in some cases degraded, which helps to limit any possibility of aberrant RNA causing harm to cellular health. These critical quality control pathways are regulated by the highly dynamic protein-protein interaction network at the site of transcription. Recent work has further revealed the extent to which the processes of transcription and RNA processing and quality control are integrated, and how critically their coupling relies upon the dynamic protein interactions that take place co-transcriptionally. This review focuses specifically on the intricate balance between 3' end processing and RNA decay during transcription termination. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Processing > 3' End Processing RNA Processing > Splicing Mechanisms RNA Processing > Capping and 5' End Modifications.
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Affiliation(s)
- Sarah A Peck
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Katlyn D Hughes
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jose F Victorino
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
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102
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Abstract
In eukaryotes, the separation of translation from transcription by the nuclear envelope enables mRNA modifications such as capping, splicing, and polyadenylation. These modifications are mediated by a spectrum of ribonuclear proteins that associate with preRNA transcripts, coordinating the different steps and coupling them to nuclear export, ensuring that only mature transcripts reach the cytoplasmic translation machinery. Although the components of this machinery have been identified and considerable functional insight has been achieved, a number of questions remain outstanding about mRNA nuclear export and how it is integrated into the nuclear phase of the gene expression pathway. Nuclear export factors mediate mRNA transit through nuclear pores to the cytoplasm, after which these factors are removed from the mRNA, preventing transcripts from returning to the nucleus. However, as outlined in this review, several aspects of the mechanism by which transport factor binding and release are mediated remain unclear, as are the roles of accessory nuclear components in these processes. Moreover, the mechanisms by which completion of mRNA splicing and polyadenylation are recognized, together with how they are coordinated with nuclear export, also remain only partially characterized. One attractive hypothesis is that dissociating poly(A) polymerase from the cleavage and polyadenylation machinery could signal completion of mRNA maturation and thereby provide a mechanism for initiating nuclear export. The impressive array of genetic, molecular, cellular, and structural data that has been generated about these systems now provides many of the tools needed to define the precise mechanisms involved in these processes and how they are integrated.
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Affiliation(s)
- Murray Stewart
- From the MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
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103
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Lu S, He X, Ni D, Zhang J. Allosteric Modulator Discovery: From Serendipity to Structure-Based Design. J Med Chem 2019; 62:6405-6421. [PMID: 30817889 DOI: 10.1021/acs.jmedchem.8b01749] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Shaoyong Lu
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Clinical and Fundamental Research Center, Renji Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
- Medicinal Bioinformatics Center, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
| | - Xinheng He
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Clinical and Fundamental Research Center, Renji Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
| | - Duan Ni
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Clinical and Fundamental Research Center, Renji Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
| | - Jian Zhang
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Clinical and Fundamental Research Center, Renji Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
- Medicinal Bioinformatics Center, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025, China
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104
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Burke JE, Longhurst AD, Merkurjev D, Sales-Lee J, Rao B, Moresco JJ, Yates JR, Li JJ, Madhani HD. Spliceosome Profiling Visualizes Operations of a Dynamic RNP at Nucleotide Resolution. Cell 2019; 173:1014-1030.e17. [PMID: 29727661 DOI: 10.1016/j.cell.2018.03.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/19/2018] [Accepted: 03/07/2018] [Indexed: 11/28/2022]
Abstract
Tools to understand how the spliceosome functions in vivo have lagged behind advances in the structural biology of the spliceosome. Here, methods are described to globally profile spliceosome-bound pre-mRNA, intermediates, and spliced mRNA at nucleotide resolution. These tools are applied to three yeast species that span 600 million years of evolution. The sensitivity of the approach enables the detection of canonical and non-canonical events, including interrupted, recursive, and nested splicing. This application of statistical modeling uncovers independent roles for the size and position of the intron and the number of introns per transcript in substrate progression through the two catalytic stages. These include species-specific inputs suggestive of spliceosome-transcriptome coevolution. Further investigations reveal the ATP-dependent discard of numerous endogenous substrates after spliceosome assembly in vivo and connect this discard to intron retention, a form of splicing regulation. Spliceosome profiling is a quantitative, generalizable global technology used to investigate an RNP central to eukaryotic gene expression.
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Affiliation(s)
- Jordan E Burke
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Adam D Longhurst
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Daria Merkurjev
- Department of Statistics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jade Sales-Lee
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Beiduo Rao
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - James J Moresco
- Department of Molecular Medicine, the Scripps Research Institute, La Jolla, CA, USA
| | - John R Yates
- Department of Molecular Medicine, the Scripps Research Institute, La Jolla, CA, USA
| | - Jingyi Jessica Li
- Department of Statistics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Hiten D Madhani
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Chan-Zuckerberg Biohub, San Francisco, CA 94158, USA.
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105
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Zhang L, Vielle A, Espinosa S, Zhao R. RNAs in the spliceosome: Insight from cryoEM structures. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1523. [PMID: 30729694 DOI: 10.1002/wrna.1523] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/12/2018] [Accepted: 12/28/2018] [Indexed: 12/28/2022]
Abstract
Pre-mRNA splicing is catalyzed by the spliceosome, a multimegadalton RNA-protein complex. The spliceosome undergoes dramatic compositional and conformational changes through the splicing cycle, forming at least 10 distinct complexes. Recent high-resolution cryoEM structures of various spliceosomal complexes revealed unprecedented details of this large molecular machine. This review highlights insight into the structure and function of the spliceosomal RNA components obtained from these new structures, with a focus on the yeast spliceosome. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
| | - Anne Vielle
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
| | - Sara Espinosa
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado
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106
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Structures of the human spliceosomes before and after release of the ligated exon. Cell Res 2019; 29:274-285. [PMID: 30728453 PMCID: PMC6461851 DOI: 10.1038/s41422-019-0143-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 01/14/2019] [Indexed: 11/08/2022] Open
Abstract
Pre-mRNA splicing is executed by the spliceosome, which has eight major functional states each with distinct composition. Five of these eight human spliceosomal complexes, all preceding exon ligation, have been structurally characterized. In this study, we report the cryo-electron microscopy structures of the human post-catalytic spliceosome (P complex) and intron lariat spliceosome (ILS) at average resolutions of 3.0 and 2.9 Å, respectively. In the P complex, the ligated exon remains anchored to loop I of U5 small nuclear RNA, and the 3′-splice site is recognized by the junction between the 5′-splice site and the branch point sequence. The ATPase/helicase Prp22, along with the ligated exon and eight other proteins, are dissociated in the P-to-ILS transition. Intriguingly, the ILS complex exists in two distinct conformations, one with the ATPase/helicase Prp43 and one without. Comparison of these three late-stage human spliceosomes reveals mechanistic insights into exon release and spliceosome disassembly.
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107
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Hill CH, Boreikaitė V, Kumar A, Casañal A, Kubík P, Degliesposti G, Maslen S, Mariani A, von Loeffelholz O, Girbig M, Skehel M, Passmore LA. Activation of the Endonuclease that Defines mRNA 3' Ends Requires Incorporation into an 8-Subunit Core Cleavage and Polyadenylation Factor Complex. Mol Cell 2019; 73:1217-1231.e11. [PMID: 30737185 PMCID: PMC6436931 DOI: 10.1016/j.molcel.2018.12.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/02/2018] [Accepted: 12/21/2018] [Indexed: 01/19/2023]
Abstract
Cleavage and polyadenylation factor (CPF/CPSF) is a multi-protein complex essential for formation of eukaryotic mRNA 3' ends. CPF cleaves pre-mRNAs at a specific site and adds a poly(A) tail. The cleavage reaction defines the 3' end of the mature mRNA, and thus the activity of the endonuclease is highly regulated. Here, we show that reconstitution of specific pre-mRNA cleavage with recombinant yeast proteins requires incorporation of the Ysh1 endonuclease into an eight-subunit "CPFcore" complex. Cleavage also requires the accessory cleavage factors IA and IB, which bind substrate pre-mRNAs and CPF, likely facilitating assembly of an active complex. Using X-ray crystallography, electron microscopy, and mass spectrometry, we determine the structure of Ysh1 bound to Mpe1 and the arrangement of subunits within CPFcore. Together, our data suggest that the active mRNA 3' end processing machinery is a dynamic assembly that is licensed to cleave only when all protein factors come together at the polyadenylation site.
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Affiliation(s)
- Chris H Hill
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | | | - Ana Casañal
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Peter Kubík
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | - Sarah Maslen
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | - Ottilie von Loeffelholz
- Centre for Integrative Biology, Department of Integrated Structural Biology, Institute of Genetics and of Molecular and Cellular Biology, Illkirch, Université de Strasbourg, Strasbourg, France; Centre National de la Recherche Scientifique UMR 7104, Illkirch, Université de Strasbourg, Strasbourg, France; INSERM U964, Illkirch, Université de Strasbourg, Strasbourg, France
| | - Mathias Girbig
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Mark Skehel
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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108
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Huertas R, Catalá R, Jiménez-Gómez JM, Mar Castellano M, Crevillén P, Piñeiro M, Jarillo JA, Salinas J. Arabidopsis SME1 Regulates Plant Development and Response to Abiotic Stress by Determining Spliceosome Activity Specificity. THE PLANT CELL 2019; 31:537-554. [PMID: 30696706 PMCID: PMC6447010 DOI: 10.1105/tpc.18.00689] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/14/2018] [Accepted: 01/25/2019] [Indexed: 05/19/2023]
Abstract
The control of precursor-messenger RNA (pre-mRNA) splicing is emerging as an important layer of regulation in plant responses to endogenous and external cues. In eukaryotes, pre-mRNA splicing is governed by the activity of a large ribonucleoprotein machinery, the spliceosome, whose protein core is composed of the Sm ring and the related Sm-like 2-8 complex. Recently, the Arabidopsis (Arabidopsis thaliana) Sm-like 2-8 complex has been characterized. However, the role of plant Sm proteins in pre-mRNA splicing remains largely unknown. Here, we present the functional characterization of Sm protein E1 (SME1), an Arabidopsis homolog of the SME subunit of the eukaryotic Sm ring. Our results demonstrate that SME1 regulates the spliceosome activity and that this regulation is controlled by the environmental conditions. Indeed, depending on the conditions, SME1 ensures the efficiency of constitutive and alternative splicing of selected pre-mRNAs. Moreover, missplicing of most targeted pre-mRNAs leads to the generation of nonsense-mediated decay signatures, indicating that SME1 also guarantees adequate levels of the corresponding functional transcripts. In addition, we show that the selective function of SME1 in ensuring appropriate gene expression patterns through the regulation of specific pre-mRNA splicing is essential for adequate plant development and adaptation to freezing temperatures. These findings reveal that SME1 plays a critical role in plant development and interaction with the environment by providing spliceosome activity specificity.
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Affiliation(s)
- Raul Huertas
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas-CSIC, 28040 Madrid, Spain
| | - Rafael Catalá
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas-CSIC, 28040 Madrid, Spain
| | | | - M Mar Castellano
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas-CSIC, 28040 Madrid, Spain
| | - Pedro Crevillén
- Centro de Biotecnología y Genómica de Plantas, UPM/INIA, 28223 Pozuelo de Alarcón, Spain
| | - Manuel Piñeiro
- Centro de Biotecnología y Genómica de Plantas, UPM/INIA, 28223 Pozuelo de Alarcón, Spain
| | - José A Jarillo
- Centro de Biotecnología y Genómica de Plantas, UPM/INIA, 28223 Pozuelo de Alarcón, Spain
| | - Julio Salinas
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas-CSIC, 28040 Madrid, Spain
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109
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Carrocci TJ, Neugebauer KM. Pre-mRNA Splicing in the Nuclear Landscape. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2019; 84:11-20. [PMID: 32493763 PMCID: PMC7384967 DOI: 10.1101/sqb.2019.84.040402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Eukaryotic gene expression requires the cumulative activity of multiple molecular machines to synthesize and process newly transcribed pre-messenger RNA. Introns, the noncoding regions in pre-mRNA, must be removed by the spliceosome, which assembles on the pre-mRNA as it is transcribed by RNA polymerase II (Pol II). The assembly and activity of the spliceosome can be modulated by features including the speed of transcription elongation, chromatin, post-translational modifications of Pol II and histone tails, and other RNA processing events like 5'-end capping. Here, we review recent work that has revealed cooperation and coordination among co-transcriptional processing events and speculate on new avenues of research. We anticipate new mechanistic insights capable of unraveling the relative contribution of coupled processing to gene expression.
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Affiliation(s)
- Tucker J Carrocci
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Karla M Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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110
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Ashraf U, Benoit-Pilven C, Lacroix V, Navratil V, Naffakh N. Advances in Analyzing Virus-Induced Alterations of Host Cell Splicing. Trends Microbiol 2018; 27:268-281. [PMID: 30577974 DOI: 10.1016/j.tim.2018.11.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/19/2018] [Accepted: 11/09/2018] [Indexed: 12/14/2022]
Abstract
Alteration of host cell splicing is a common feature of many viral infections which is underappreciated because of the complexity and technical difficulty of studying alternative splicing (AS) regulation. Recent advances in RNA sequencing technologies revealed that up to several hundreds of host genes can show altered mRNA splicing upon viral infection. The observed changes in AS events can be either a direct consequence of viral manipulation of the host splicing machinery or result indirectly from the virus-induced innate immune response or cellular damage. Analysis at a higher resolution with single-cell RNAseq, and at a higher scale with the integration of multiple omics data sets in a systems biology perspective, will be needed to further comprehend this complex facet of virus-host interactions.
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Affiliation(s)
- Usama Ashraf
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Département de Virologie, F-75015 Paris, France; CNRS UMR3569, F-75015 Paris, France; Université Paris Diderot, Sorbonne Paris Cité EA302, F-75015 Paris, France
| | - Clara Benoit-Pilven
- INSERM U1028; CNRS UMR5292, Lyon Neuroscience Research Center, Genetic of Neuro-development Anomalies Team, F-69000 Lyon, France; Université Claude Bernard Lyon 1, CNRS UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France; EPI ERABLE, INRIA Grenoble Rhône-Alpes, F-38330 Montbonnot Saint-Martin, France
| | - Vincent Lacroix
- Université Claude Bernard Lyon 1, CNRS UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France; EPI ERABLE, INRIA Grenoble Rhône-Alpes, F-38330 Montbonnot Saint-Martin, France
| | - Vincent Navratil
- PRABI, Rhône Alpes Bioinformatics Center, UCBL, Université Claude Bernard Lyon 1, F-69000 Lyon, France; European Virus Bioinformatics Center, Leutragraben 1, D-07743 Jena, Germany
| | - Nadia Naffakh
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Département de Virologie, F-75015 Paris, France; CNRS UMR3569, F-75015 Paris, France; Université Paris Diderot, Sorbonne Paris Cité EA302, F-75015 Paris, France.
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111
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Torgerson CD, Hiller DA, Stav S, Strobel SA. Gene regulation by a glycine riboswitch singlet uses a finely tuned energetic landscape for helical switching. RNA (NEW YORK, N.Y.) 2018; 24:1813-1827. [PMID: 30237163 PMCID: PMC6239177 DOI: 10.1261/rna.067884.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/18/2018] [Indexed: 05/09/2023]
Abstract
Riboswitches contain structured aptamer domains that, upon ligand binding, facilitate helical switching in their downstream expression platforms to alter gene expression. To fully dissect how riboswitches function requires a better understanding of the energetic landscape for helical switching. Here, we report a sequencing-based high-throughput assay for monitoring in vitro transcription termination and use it to simultaneously characterize the functional effects of all 522 single point mutants of a glycine riboswitch type-1 singlet. Mutations throughout the riboswitch cause ligand-dependent defects, but only mutations within the terminator hairpin alter readthrough efficiencies in the absence of ligand. A comprehensive analysis of the expression platform reveals that ligand binding stabilizes the antiterminator by just 2-3 kcal/mol, indicating that the competing expression platform helices must be extremely close in energy to elicit a significant ligand-dependent response. These results demonstrate that gene regulation by this riboswitch is highly constrained by the energetics of ligand binding and conformational switching. These findings exemplify the energetic parameters of RNA conformational rearrangements driven by binding events.
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Affiliation(s)
- Chad D Torgerson
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, USA
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - David A Hiller
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Shira Stav
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
| | - Scott A Strobel
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, USA
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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112
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Zhan X, Yan C, Zhang X, Lei J, Shi Y. Structures of the human pre-catalytic spliceosome and its precursor spliceosome. Cell Res 2018; 28:1129-1140. [PMID: 30315277 PMCID: PMC6274647 DOI: 10.1038/s41422-018-0094-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 12/13/2022] Open
Abstract
The pre-catalytic spliceosome (B complex) is preceded by its precursor spliceosome (pre-B complex) and followed by the activated spliceosome (Bact complex). The pre-B-to-B and B-to-Bact transitions are driven by the ATPase/helicases Prp28 and Brr2, respectively. In this study, we report the cryo-electron microscopy structures of the human pre-B complex and the human B complex at an average resolution of 5.7 and 3.8 Å, respectively. In the pre-B complex, U1 and U2 small nuclear ribonucleoproteins (snRNPs) associate with two edges of the tetrahedron-shaped U4/U6.U5 tri-snRNP. The pre-mRNA is yet to be recognized by U5 or U6 small nuclear RNA (snRNA), and loop I of U5 snRNA remains unengaged. In the B complex, U1 snRNP and Prp28 are dissociated, the 5'-exon is anchored to loop I of U5 snRNA, and the 5'-splice site is recognized by U6 snRNA through duplex formation. In sharp contrast to S. cerevisiae, most components of U2 snRNP and tri-snRNP, exemplified by Brr2, undergo pronounced rearrangements in the human pre-B-to-B transition. Structural analysis reveals mechanistic insights into the assembly and activation of the human spliceosome.
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Affiliation(s)
- Xiechao Zhan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Chuangye Yan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, 100084, China.
| | - Xiaofeng Zhang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, 100084, China
- Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, 100084, China.
- Institute of Biology, Westlake Institute for Advanced Study, Westlake University, 18 Shilongshan Road, Xihu District, Hangzhou, Zhejiang, 310024, China.
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113
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Nomura Y, Roston D, Montemayor EJ, Cui Q, Butcher SE. Structural and mechanistic basis for preferential deadenylation of U6 snRNA by Usb1. Nucleic Acids Res 2018; 46:11488-11501. [PMID: 30215753 PMCID: PMC6265477 DOI: 10.1093/nar/gky812] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 01/08/2023] Open
Abstract
Post-transcriptional modification of snRNA is central to spliceosome function. Usb1 is an exoribonuclease that shortens the oligo-uridine tail of U6 snRNA, resulting in a terminal 2',3' cyclic phosphate group in most eukaryotes, including humans. Loss of function mutations in human Usb1 cause the rare disorder poikiloderma with neutropenia (PN), and result in U6 snRNAs with elongated 3' ends that are aberrantly adenylated. Here, we show that human Usb1 removes 3' adenosines with 20-fold greater efficiency than uridines, which explains the presence of adenylated U6 snRNAs in cells lacking Usb1. We determined three high-resolution co-crystal structures of Usb1: wild-type Usb1 bound to the substrate analog adenosine 5'-monophosphate, and an inactive mutant bound to RNAs with a 3' terminal adenosine and uridine. These structures, along with QM/MM MD simulations of the catalytic mechanism, illuminate the molecular basis for preferential deadenylation of U6 snRNA. The extent of Usb1 processing is influenced by the secondary structure of U6 snRNA.
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Affiliation(s)
- Yuichiro Nomura
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Daniel Roston
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Eric J Montemayor
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Qiang Cui
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
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114
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Escobar-Hoyos L, Knorr K, Abdel-Wahab O. Aberrant RNA Splicing in Cancer. ANNUAL REVIEW OF CANCER BIOLOGY-SERIES 2018; 3:167-185. [PMID: 32864546 DOI: 10.1146/annurev-cancerbio-030617-050407] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
RNA splicing, the enzymatic process of removing segments of premature RNA to produce mature RNA, is a key mediator of proteome diversity and regulator of gene expression. Increased systematic sequencing of the genome and transcriptome of cancers has identified a variety of means by which RNA splicing is altered in cancer relative to normal cells. These findings, in combination with the discovery of recurrent change-of-function mutations in splicing factors in a variety of cancers, suggest that alterations in splicing are drivers of tumorigenesis. Greater characterization of altered splicing in cancer parallels increasing efforts to pharmacologically perturb splicing and early-phase clinical development of small molecules that disrupt splicing in patients with cancer. Here we review recent studies of global changes in splicing in cancer, splicing regulation of mitogenic pathways critical in cancer transformation, and efforts to therapeutically target splicing in cancer.
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Affiliation(s)
- Luisa Escobar-Hoyos
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.,David M. Rubenstein Center for Pancreatic Cancer Research, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.,Department of Pathology, Stony Brook University, Stony Brook, NY 11794, USA
| | | | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.,Weill Cornell Medical College, New York, NY 10065, USA.,Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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115
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Kaur H, Jamalidinan F, Condon SGF, Senes A, Hoskins AA. Analysis of spliceosome dynamics by maximum likelihood fitting of dwell time distributions. Methods 2018; 153:13-21. [PMID: 30472247 DOI: 10.1016/j.ymeth.2018.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 11/17/2022] Open
Abstract
Colocalization single-molecule methods can provide a wealth of information concerning the ordering and dynamics of biomolecule assembly. These have been used extensively to study the pathways of spliceosome assembly in vitro. Key to these experiments is the measurement of binding times-either the dwell times of a multi-molecular interaction or times in between binding events. By analyzing hundreds of these times, many new insights into the kinetic pathways governing spliceosome assembly have been obtained. Collections of binding times are often plotted as histograms and can be fit to kinetic models using a variety of methods. Here, we describe the use of maximum likelihood methods to fit dwell time distributions without binning. In addition, we discuss several aspects of analyzing these distributions with histograms and pitfalls that can be encountered if improperly binned histograms are used. We have automated several aspects of maximum likelihood fitting of dwell time distributions in the AGATHA software package.
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Affiliation(s)
- Harpreet Kaur
- Department of Biochemistry, 433 Babcock Dr., University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Fatemehsadat Jamalidinan
- Department of Biochemistry, 433 Babcock Dr., University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Samson G F Condon
- Department of Biochemistry, 433 Babcock Dr., University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alessandro Senes
- Department of Biochemistry, 433 Babcock Dr., University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Aaron A Hoskins
- Department of Biochemistry, 433 Babcock Dr., University of Wisconsin-Madison, Madison, WI 53706, USA.
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116
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Structural studies of the spliceosome: past, present and future perspectives. Biochem Soc Trans 2018; 46:1407-1422. [PMID: 30420411 DOI: 10.1042/bst20170240] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 12/18/2022]
Abstract
The spliceosome is a multi-subunit RNA-protein complex involved in the removal of non-coding segments (introns) from between the coding regions (exons) in precursors of messenger RNAs (pre-mRNAs). Intron removal proceeds via two transesterification reactions, occurring between conserved sequences at intron-exon junctions. A tightly regulated, hierarchical assembly with a multitude of structural and compositional rearrangements posed a great challenge for structural studies of the spliceosome. Over the years, X-ray crystallography dominated the field, providing valuable high-resolution structural information that was mostly limited to individual proteins and smaller sub-complexes. Recent developments in the field of cryo-electron microscopy allowed the visualisation of fully assembled yeast and human spliceosomes, providing unprecedented insights into substrate recognition, catalysis, and active site formation. This has advanced our mechanistic understanding of pre-mRNA splicing enormously.
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117
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Kappel K, Liu S, Larsen KP, Skiniotis G, Puglisi EV, Puglisi JD, Zhou ZH, Zhao R, Das R. De novo computational RNA modeling into cryo-EM maps of large ribonucleoprotein complexes. Nat Methods 2018; 15:947-954. [PMID: 30377372 PMCID: PMC6636682 DOI: 10.1038/s41592-018-0172-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 07/31/2018] [Indexed: 12/19/2022]
Abstract
Increasingly, cryo-electron microscopy (cryo-EM) is used to determine the structures of RNA-protein assemblies, but nearly all maps determined with this method have biologically important regions where the local resolution does not permit RNA coordinate tracing. To address these omissions, we present de novo ribonucleoprotein modeling in real space through assembly of fragments together with experimental density in Rosetta (DRRAFTER). We show that DRRAFTER recovers near-native models for a diverse benchmark set of RNA-protein complexes including the spliceosome, mitochondrial ribosome, and CRISPR-Cas9-sgRNA complexes; rigorous blind tests include yeast U1 snRNP and spliceosomal P complex maps. Additionally, to aid in model interpretation, we present a method for reliable in situ estimation of DRRAFTER model accuracy. Finally, we apply DRRAFTER to recently determined maps of telomerase, the HIV-1 reverse transcriptase initiation complex, and the packaged MS2 genome, demonstrating the acceleration of accurate model building in challenging cases.
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Affiliation(s)
- Kalli Kappel
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Shiheng Liu
- Electron Imaging Center for Nanomachines, California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
| | - Kevin P Larsen
- Biophysics Program, Stanford University, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Georgios Skiniotis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
- Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Z Hong Zhou
- Electron Imaging Center for Nanomachines, California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, USA
| | - Rhiju Das
- Biophysics Program, Stanford University, Stanford, CA, USA.
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Physics, Stanford University, Stanford, CA, USA.
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118
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Abstract
Cryo-electron microscopy, or simply cryo-EM, refers mainly to three very different yet closely related techniques: electron crystallography, single-particle cryo-EM, and electron cryotomography. In the past few years, single-particle cryo-EM in particular has triggered a revolution in structural biology and has become a newly dominant discipline. This Review examines the fascinating story of its start and evolution over the past 40-plus years, delves into how and why the recent technological advances have been so groundbreaking, and briefly considers where the technique may be headed in the future.
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Affiliation(s)
- Yifan Cheng
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
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119
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The Development and Use of Scalable Systems for Studying Aberrant Splicing in SF3B1-Mutant CLL. Methods Mol Biol 2018. [PMID: 30350199 DOI: 10.1007/978-1-4939-8876-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Mutational landscape of CLL is now known to include recurrent non-synonymous mutations in SF3B1, a core splicing factor. About 5-10% of newly diagnosed CLL harbor these mutations which are typically limited to HEAT domains in the carboxyl-terminus of the protein. Importantly, the mutations are not specific to CLL but also present in several unrelated clonal disorders. Analysis of patient samples and cell lines has shown the primary splicing aberration in SF3B1-mutant cells to the use of novel or "cryptic" 3' splice sites (3SS). Advances in genome-editing and next-generation sequencing (NGS) have allowed development of isogenic models and detailed analysis of changes to the transcriptome with relative ease. In this manuscript, we focus on two relevant methods to study splicing factor mutations in CLL: development of isogenic scalable cell lines and informatics analysis of RNA-Seq datasets.
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120
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Zahler AM, Rogel LE, Glover ML, Yitiz S, Ragle JM, Katzman S. SNRP-27, the C. elegans homolog of the tri-snRNP 27K protein, has a role in 5' splice site positioning in the spliceosome. RNA (NEW YORK, N.Y.) 2018; 24:1314-1325. [PMID: 30006499 PMCID: PMC6140464 DOI: 10.1261/rna.066878.118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/12/2018] [Indexed: 05/04/2023]
Abstract
The tri-snRNP 27K protein is a component of the human U4/U6-U5 tri-snRNP and contains an N-terminal phosphorylated RS domain. In a forward genetic screen in C. elegans, we previously identified a dominant mutation, M141T, in the highly-conserved C-terminal region of this protein. The mutant allele promotes changes in cryptic 5' splice site choice. To better understand the function of this poorly characterized splicing factor, we performed high-throughput mRNA sequencing analysis on worms containing this dominant mutation. Comparison of alternative splice site usage between the mutant and wild-type strains led to the identification of 26 native genes whose splicing changes in the presence of the snrp-27 mutation. The changes in splicing are specific to alternative 5' splice sites. Analysis of new alleles suggests that snrp-27 is an essential gene for worm viability. We performed a novel directed-mutation experiment in which we used the CRISPR-cas9 system to randomly generate mutations specifically at M141 of SNRP-27. We identified eight amino acid substitutions at this position that are viable, and three that are homozygous lethal. All viable substitutions at M141 led to varying degrees of changes in alternative 5' splicing of native targets. We hypothesize a role for this SR-related factor in maintaining the position of the 5' splice site as U1snRNA trades interactions at the 5' end of the intron with U6snRNA and PRP8 as the catalytic site is assembled.
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Affiliation(s)
- Alan M Zahler
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Lucero E Rogel
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Marissa L Glover
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Samira Yitiz
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - J Matthew Ragle
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Sol Katzman
- Center for Biomolecular Science and Engineering, University of California Santa Cruz, Santa Cruz, California 95064, USA
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121
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Prespliceosome structure provides insights into spliceosome assembly and regulation. Nature 2018; 559:419-422. [PMID: 29995849 PMCID: PMC6141012 DOI: 10.1038/s41586-018-0323-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/16/2018] [Indexed: 11/17/2022]
Abstract
The spliceosome catalyzes the excision of introns from pre-mRNA in two steps, branching
and exon ligation, and is assembled from five small nuclear ribonucleoprotein
particles (snRNPs; U1, U2, U4, U5, U6) and numerous non-snRNP factors1. For branching, the intron
5'-splice site (5'SS) and the branch point (BP) sequence are
selected and brought into the prespliceosome by the U1 and U2 snRNPs1, which is a focal point for the regulation
by alternative splicing factors2. The
U4/U6.U5 tri-snRNP subsequently joins the prespliceosome to form the complete
pre-catalytic spliceosome. Recent studies have revealed the structural basis of
the branching and exon-ligation reactions3. However, the structural basis of early spliceosome assembly events
remains poorly understood4. Here we report
the cryo-electron microscopy structure of the yeast Saccharomyces
cerevisiae prespliceosome at near-atomic resolution. The structure
reveals an induced stabilization of the 5'SS in the U1 snRNP, and
provides structural insights into the functions of the human alternative
splicing factors LUC7-like (yeast Luc7) and TIA-1 (yeast Nam8) that are linked
to human disease5,6. In the prespliceosome, the U1 snRNP associates with the
U2 snRNP through a stable contact with the U2 3' domain and a transient
yeast-specific contact with the U2 SF3b-containing 5' region, leaving its
tri-snRNP-binding interface fully exposed. The results suggest mechanisms for
5'SS transfer to the U6 ACAGAGA region within the assembled spliceosome
and for its subsequent conversion to the activation-competent B complex
spliceosome7,8. Taken together, the data provide a working model to
investigate the early steps of spliceosome assembly.
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122
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Mohr G, Kang SYS, Park SK, Qin Y, Grohman J, Yao J, Stamos JL, Lambowitz AM. A Highly Proliferative Group IIC Intron from Geobacillus stearothermophilus Reveals New Features of Group II Intron Mobility and Splicing. J Mol Biol 2018; 430:2760-2783. [PMID: 29913158 DOI: 10.1016/j.jmb.2018.06.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 05/01/2018] [Accepted: 06/05/2018] [Indexed: 12/13/2022]
Abstract
The thermostable Geobacillus stearothermophilus GsI-IIC intron is among the few bacterial group II introns found to proliferate to high copy number in its host genome. Here, we developed a bacterial genetic assay for retrohoming and biochemical assays for protein-dependent and self-splicing of GsI-IIC. We found that GsI-IIC, like other group IIC introns, retrohomes into sites having a 5'-exon DNA hairpin, typically from a bacterial transcription terminator, followed by short intron-binding sequences (IBSs) recognized by base pairing of exon-binding sequences (EBSs) in the intron RNA. Intron RNA insertion occurs preferentially but not exclusively into the parental lagging strand at DNA replication forks, using a nascent lagging strand DNA as a primer for reverse transcription. In vivo mobility assays, selections, and mutagenesis indicated that a variety of GC-rich DNA hairpins of 7-19 bp with continuous base pairs or internal elbow regions support efficient intron mobility and identified a critically recognized nucleotide (T-5) between the hairpin and IBS1, a feature not reported previously for group IIC introns. Neither the hairpin nor T-5 is required for intron excision or lariat formation during RNA splicing, but the 5'-exon sequence can affect the efficiency of exon ligation. Structural modeling suggests that the 5'-exon DNA hairpin and T-5 bind to the thumb and DNA-binding domains of GsI-IIC reverse transcriptase. This mode of DNA target site recognition enables the intron to proliferate to high copy number by recognizing numerous transcription terminators and then finding the best match for the EBS/IBS interactions within a short distance downstream.
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Affiliation(s)
- Georg Mohr
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Sean Yoon-Seo Kang
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Seung Kuk Park
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Yidan Qin
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jacob Grohman
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jun Yao
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jennifer L Stamos
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Alan M Lambowitz
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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123
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All-atom simulations disentangle the functional dynamics underlying gene maturation in the intron lariat spliceosome. Proc Natl Acad Sci U S A 2018; 115:6584-6589. [PMID: 29891649 DOI: 10.1073/pnas.1802963115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The spliceosome (SPL) is a majestic macromolecular machinery composed of five small nuclear RNAs and hundreds of proteins. SPL removes noncoding introns from precursor messenger RNAs (pre-mRNAs) and ligates coding exons, giving rise to functional mRNAs. Building on the first SPL structure solved at near-atomic-level resolution, here we elucidate the functional dynamics of the intron lariat spliceosome (ILS) complex through multi-microsecond-long molecular-dynamics simulations of ∼1,000,000 atoms models. The ILS essential dynamics unveils (i) the leading role of the Spp42 protein, which heads the gene maturation by tuning the motions of distinct SPL components, and (ii) the critical participation of the Cwf19 protein in displacing the intron lariat/U2 branch helix. These findings provide unprecedented details on the SPL functional dynamics, thus contributing to move a step forward toward a thorough understanding of eukaryotic pre-mRNA splicing.
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124
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Bai R, Wan R, Yan C, Lei J, Shi Y. Structures of the fully assembled Saccharomyces cerevisiae spliceosome before activation. Science 2018; 360:1423-1429. [PMID: 29794219 DOI: 10.1126/science.aau0325] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 05/16/2018] [Indexed: 11/02/2022]
Abstract
The precatalytic spliceosome (B complex) is preceded by the pre-B complex. Here we report the cryo-electron microscopy structures of the Saccharomyces cerevisiae pre-B and B complexes at average resolutions of 3.3 to 4.6 and 3.9 angstroms, respectively. In the pre-B complex, the duplex between the 5' splice site (5'SS) and U1 small nuclear RNA (snRNA) is recognized by Yhc1, Luc7, and the Sm ring. In the B complex, U1 small nuclear ribonucleoprotein is dissociated, the 5'-exon-5'SS sequences are translocated near U6 snRNA, and three B-specific proteins may orient the precursor messenger RNA. In both complexes, U6 snRNA is anchored to loop I of U5 snRNA, and the duplex between the branch point sequence and U2 snRNA is recognized by the SF3b complex. Structural analysis reveals the mechanism of assembly and activation for the yeast spliceosome.
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Affiliation(s)
- Rui Bai
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Schools of Life Sciences and Medicine, Tsinghua University, Beijing 100084, China
| | - Ruixue Wan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Schools of Life Sciences and Medicine, Tsinghua University, Beijing 100084, China
| | - Chuangye Yan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Schools of Life Sciences and Medicine, Tsinghua University, Beijing 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Schools of Life Sciences and Medicine, Tsinghua University, Beijing 100084, China.,Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Schools of Life Sciences and Medicine, Tsinghua University, Beijing 100084, China. .,Institute of Biology, Westlake Institute for Advanced Study, Westlake University, 18 Shilongshan Road, Xihu District, Hangzhou 310064, Zhejiang Province, China
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125
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Architecture of the U6 snRNP reveals specific recognition of 3'-end processed U6 snRNA. Nat Commun 2018; 9:1749. [PMID: 29717126 PMCID: PMC5931518 DOI: 10.1038/s41467-018-04145-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/06/2018] [Indexed: 01/09/2023] Open
Abstract
The spliceosome removes introns from precursor messenger RNA (pre-mRNA) to produce mature mRNA. Prior to catalysis, spliceosomes are assembled de novo onto pre-mRNA substrates. During this assembly process, U6 small nuclear RNA (snRNA) undergoes extensive structural remodeling. The early stages of this remodeling process are chaperoned by U6 snRNP proteins Prp24 and the Lsm2-8 heteroheptameric ring. We now report a structure of the U6 snRNP from Saccharomyces cerevisiae. The structure reveals protein-protein contacts that position Lsm2-8 in close proximity to the chaperone "active site" of Prp24. The structure also shows how the Lsm2-8 ring specifically recognizes U6 snRNA that has been post-transcriptionally modified at its 3' end, thereby elucidating the mechanism by which U6 snRNPs selectively recruit 3' end-processed U6 snRNA into spliceosomes. Additionally, the structure reveals unanticipated homology between the C-terminal regions of Lsm8 and the cytoplasmic Lsm1 protein involved in mRNA decay.
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126
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Capturing dynamic conformational shifts in protein–ligand recognition using integrative structural biology in solution. Emerg Top Life Sci 2018; 2:107-119. [DOI: 10.1042/etls20170090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 03/18/2018] [Accepted: 03/20/2018] [Indexed: 11/17/2022]
Abstract
In recent years, a dynamic view of the structure and function of biological macromolecules is emerging, highlighting an essential role of dynamic conformational equilibria to understand molecular mechanisms of biological functions. The structure of a biomolecule, i.e. protein or nucleic acid in solution, is often best described as a dynamic ensemble of conformations, rather than a single structural state. Strikingly, the molecular interactions and functions of the biological macromolecule can then involve a shift between conformations that pre-exist in such an ensemble. Upon external cues, such population shifts of pre-existing conformations allow gradually relaying the signal to the downstream biological events. An inherent feature of this principle is conformational dynamics, where intrinsically disordered regions often play important roles to modulate the conformational ensemble. Unequivocally, solution-state NMR spectroscopy is a powerful technique to study the structure and dynamics of such biomolecules in solution. NMR is increasingly combined with complementary techniques, including fluorescence spectroscopy and small angle scattering. The combination of these techniques provides complementary information about the conformation and dynamics in solution and thus affords a comprehensive description of biomolecular functions and regulations. Here, we illustrate how an integrated approach combining complementary techniques can assess the structure and dynamics of proteins and protein complexes in solution.
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127
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Cretu C, Agrawal AA, Cook A, Will CL, Fekkes P, Smith PG, Lührmann R, Larsen N, Buonamici S, Pena V. Structural Basis of Splicing Modulation by Antitumor Macrolide Compounds. Mol Cell 2018; 70:265-273.e8. [DOI: 10.1016/j.molcel.2018.03.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/07/2018] [Accepted: 03/07/2018] [Indexed: 12/22/2022]
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128
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Zhang X, Yan C, Zhan X, Li L, Lei J, Shi Y. Structure of the human activated spliceosome in three conformational states. Cell Res 2018; 28:307-322. [PMID: 29360106 PMCID: PMC5835773 DOI: 10.1038/cr.2018.14] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 01/02/2018] [Accepted: 01/08/2018] [Indexed: 12/13/2022] Open
Abstract
During each cycle of pre-mRNA splicing, the pre-catalytic spliceosome (B complex) is converted into the activated spliceosome (Bact complex), which has a well-formed active site but cannot proceed to the branching reaction. Here, we present the cryo-EM structure of the human Bact complex in three distinct conformational states. The EM map allows atomic modeling of nearly all protein components of the U2 small nuclear ribonucleoprotein (snRNP), including three of the SF3a complex and seven of the SF3b complex. The structure of the human Bact complex contains 52 proteins, U2, U5, and U6 small nuclear RNA (snRNA), and a pre-mRNA. Three distinct conformations have been captured, representing the early, mature, and late states of the human Bact complex. These complexes differ in the orientation of the Switch loop of Prp8, the splicing factors RNF113A and NY-CO-10, and most components of the NineTeen complex (NTC) and the NTC-related complex. Analysis of these three complexes and comparison with the B and C complexes reveal an ordered flux of components in the B-to-Bact and the Bact-to-B* transitions, which ultimately prime the active site for the branching reaction.
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Affiliation(s)
- Xiaofeng Zhang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Chuangye Yan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Xiechao Zhan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Lijia Li
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Shilongshan Road No. 18, Hangzhou, Zhejiang 310064, China
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129
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Madej MG, Ziegler CM. Dawning of a new era in TRP channel structural biology by cryo-electron microscopy. Pflugers Arch 2018; 470:213-225. [PMID: 29344776 DOI: 10.1007/s00424-018-2107-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 01/03/2018] [Indexed: 12/20/2022]
Abstract
Cryo-electron microscopy (cryo-EM) permits the determination of atomic protein structures by averaging large numbers of individual projection images recorded at cryogenic temperatures-a method termed single-particle analysis. The cryo-preservation traps proteins within a thin glass-like ice layer, making literally a freeze image of proteins in solution. Projections of randomly adopted orientations are merged to reconstruct a 3D density map. While atomic resolution for highly symmetric viruses was achieved already in 2009, the development of new sensitive and fast electron detectors has enabled cryo-EM for smaller and asymmetrical proteins including fragile membrane proteins. As one of the most important structural biology methods at present, cryo-EM was awarded in October 2017 with the Nobel Prize in Chemistry. The molecular understanding of Transient-Receptor-Potential (TRP) channels has been boosted tremendously by cryo-EM single-particle analysis. Several near-atomic and atomic structures gave important mechanistic insights, e.g., into ion permeation and selectivity, gating, as well as into the activation of this enigmatic and medically important membrane protein family by various chemical and physical stimuli. Lastly, these structures have set the starting point for the rational design of TRP channel-targeted therapeutics to counteract life-threatening channelopathies. Here, we attempt a brief introduction to the method, review the latest advances in cryo-EM structure determination of TRP channels, and discuss molecular insights into the channel function based on the wealth of TRP channel cryo-EM structures.
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Affiliation(s)
- M Gregor Madej
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstrasse 31, D-93053, Regensburg, Germany
| | - Christine M Ziegler
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstrasse 31, D-93053, Regensburg, Germany.
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130
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Wilkinson ME, Fica SM, Galej WP, Norman CM, Newman AJ, Nagai K. Postcatalytic spliceosome structure reveals mechanism of 3'-splice site selection. Science 2017; 358:1283-1288. [PMID: 29146871 DOI: 10.1126/science.aar3729] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 11/09/2017] [Indexed: 12/27/2022]
Abstract
Introns are removed from eukaryotic messenger RNA precursors by the spliceosome in two transesterification reactions-branching and exon ligation. The mechanism of 3'-splice site recognition during exon ligation has remained unclear. Here we present the 3.7-angstrom cryo-electron microscopy structure of the yeast P-complex spliceosome immediately after exon ligation. The 3'-splice site AG dinucleotide is recognized through non-Watson-Crick pairing with the 5' splice site and the branch-point adenosine. After the branching reaction, protein factors work together to remodel the spliceosome and stabilize a conformation competent for 3'-splice site docking, thereby promoting exon ligation. The structure accounts for the strict conservation of the GU and AG dinucleotides at the 5' and 3' ends of introns and provides insight into the catalytic mechanism of exon ligation.
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Affiliation(s)
- Max E Wilkinson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
| | - Sebastian M Fica
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | | | | | | | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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