1
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Atkinson R, Georgiou M, Yang C, Szymanska K, Lahat A, Vasconcelos EJR, Ji Y, Moya Molina M, Collin J, Queen R, Dorgau B, Watson A, Kurzawa-Akanbi M, Laws R, Saxena A, Shyan Beh C, Siachisumo C, Goertler F, Karwatka M, Davey T, Inglehearn CF, McKibbin M, Lührmann R, Steel DH, Elliott DJ, Armstrong L, Urlaub H, Ali RR, Grellscheid SN, Johnson CA, Mozaffari-Jovin S, Lako M. PRPF8-mediated dysregulation of hBrr2 helicase disrupts human spliceosome kinetics and 5´-splice-site selection causing tissue-specific defects. Nat Commun 2024; 15:3138. [PMID: 38605034 PMCID: PMC11009313 DOI: 10.1038/s41467-024-47253-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 03/19/2024] [Indexed: 04/13/2024] Open
Abstract
The carboxy-terminus of the spliceosomal protein PRPF8, which regulates the RNA helicase Brr2, is a hotspot for mutations causing retinitis pigmentosa-type 13, with unclear role in human splicing and tissue-specificity mechanism. We used patient induced pluripotent stem cells-derived cells, carrying the heterozygous PRPF8 c.6926 A > C (p.H2309P) mutation to demonstrate retinal-specific endophenotypes comprising photoreceptor loss, apical-basal polarity and ciliary defects. Comprehensive molecular, transcriptomic, and proteomic analyses revealed a role of the PRPF8/Brr2 regulation in 5'-splice site (5'SS) selection by spliceosomes, for which disruption impaired alternative splicing and weak/suboptimal 5'SS selection, and enhanced cryptic splicing, predominantly in ciliary and retinal-specific transcripts. Altered splicing efficiency, nuclear speckles organisation, and PRPF8 interaction with U6 snRNA, caused accumulation of active spliceosomes and poly(A)+ mRNAs in unique splicing clusters located at the nuclear periphery of photoreceptors. Collectively these elucidate the role of PRPF8/Brr2 regulatory mechanisms in splicing and the molecular basis of retinal disease, informing therapeutic approaches.
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Affiliation(s)
| | - Maria Georgiou
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Chunbo Yang
- Biosciences Institute, Newcastle University, Newcastle, UK
| | | | - Albert Lahat
- Department of Biosciences, Durham University, Durham, UK
| | | | - Yanlong Ji
- Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Marina Moya Molina
- Biosciences Institute, Newcastle University, Newcastle, UK
- Newcells Biotech, Newcastle, UK
| | - Joseph Collin
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Rachel Queen
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Birthe Dorgau
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Avril Watson
- Biosciences Institute, Newcastle University, Newcastle, UK
- Newcells Biotech, Newcastle, UK
| | | | - Ross Laws
- Electron Microscopy Research Services, Newcastle University, Newcastle, UK
| | - Abhijit Saxena
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Chia Shyan Beh
- Biosciences Institute, Newcastle University, Newcastle, UK
| | | | | | | | - Tracey Davey
- Electron Microscopy Research Services, Newcastle University, Newcastle, UK
| | | | - Martin McKibbin
- Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Reinhard Lührmann
- Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - David H Steel
- Biosciences Institute, Newcastle University, Newcastle, UK
| | | | - Lyle Armstrong
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Henning Urlaub
- Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences, Georg August University of Göttingen, Göttingen, Germany
| | - Robin R Ali
- Centre for Cell and Gene Therapy, Kings College London, London, UK
| | - Sushma-Nagaraja Grellscheid
- Department of Biosciences, Durham University, Durham, UK
- Department of Informatics, University of Bergen, Bergen, Norway
| | - Colin A Johnson
- Leeds Institute of Medical Research, University of Leeds, Leeds, UK.
| | - Sina Mozaffari-Jovin
- Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany.
- Department of Medical Genetics and Medical Genetics Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
| | - Majlinda Lako
- Biosciences Institute, Newcastle University, Newcastle, UK.
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2
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Batista M, Langendijk-Genevaux P, Kwapisz M, Canal I, Phung DK, Plassart L, Capeyrou R, Moalic Y, Jebbar M, Flament D, Fichant G, Bouvier M, Clouet-d'Orval B. Evolutionary and functional insights into the Ski2-like helicase family in Archaea: a comparison of Thermococcales ASH-Ski2 and Hel308 activities. NAR Genom Bioinform 2024; 6:lqae026. [PMID: 38500564 PMCID: PMC10946056 DOI: 10.1093/nargab/lqae026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 02/19/2024] [Accepted: 02/27/2024] [Indexed: 03/20/2024] Open
Abstract
RNA helicases perform essential housekeeping and regulatory functions in all domains of life by binding and unwinding RNA molecules. The Ski2-like proteins are primordial helicases that play an active role in eukaryotic RNA homeostasis pathways, with multiple homologs having specialized functions. The significance of the expansion and diversity of Ski2-like proteins in Archaea, the third domain of life, has not yet been established. Here, by studying the phylogenetic diversity of Ski2-like helicases among archaeal genomes and the enzymatic activities of those in Thermococcales, we provide further evidence of the function of this protein family in archaeal metabolism of nucleic acids. We show that, in the course of evolution, ASH-Ski2 and Hel308-Ski2, the two main groups of Ski2-like proteins, have diverged in their biological functions. Whereas Hel308 has been shown to mainly act on DNA, we show that ASH-Ski2, previously described to be associated with the 5'-3' aRNase J exonuclease, acts on RNA by supporting an efficient annealing activity, but also an RNA unwinding with a 3'-5' polarity. To gain insights into the function of Ski2, we also analyse the transcriptome of Thermococcus barophilus ΔASH-Ski2 mutant strain and provide evidence of the importance of ASH-Ski2 in cellular metabolism pathways related to translation.
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Affiliation(s)
- Manon Batista
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | | | - Marta Kwapisz
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Isabelle Canal
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Duy Khanh Phung
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Laura Plassart
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Régine Capeyrou
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Yann Moalic
- Univ Brest, CNRS, Ifremer, UMR6197 Biologie et Ecologie des Ecosystèmes marins Profonds, F-29280 Plouzané, France
| | - Mohamed Jebbar
- Univ Brest, CNRS, Ifremer, UMR6197 Biologie et Ecologie des Ecosystèmes marins Profonds, F-29280 Plouzané, France
| | - Didier Flament
- Univ Brest, CNRS, Ifremer, UMR6197 Biologie et Ecologie des Ecosystèmes marins Profonds, F-29280 Plouzané, France
| | - Gwennaele Fichant
- LMGM, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Marie Bouvier
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Béatrice Clouet-d'Orval
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
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3
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Cartwright-Acar CH, Osterhoudt K, Suzuki JMNGL, Gomez D, Katzman S, Zahler AM. A forward genetic screen in C. elegans identifies conserved residues of spliceosomal proteins PRP8 and SNRNP200/BRR2 with a role in maintaining 5' splice site identity. Nucleic Acids Res 2022; 50:11834-11857. [PMID: 36321655 PMCID: PMC9723624 DOI: 10.1093/nar/gkac991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 11/07/2022] Open
Abstract
The spliceosome undergoes extensive rearrangements as it assembles onto precursor messenger RNAs. In the earliest assembly step, U1snRNA identifies the 5' splice site. However, U1snRNA leaves the spliceosome relatively early in assembly, and 5' splice site identity is subsequently maintained through interactions with U6snRNA, protein factor PRP8, and other components during the rearrangements that build the catalytic site. Using a forward genetic screen in Caenorhabditis elegans, we have identified suppressors of a locomotion defect caused by a 5'ss mutation. Here we report three new suppressor alleles from this screen, two in PRP8 and one in SNRNP200/BRR2. mRNASeq studies of these suppressor strains indicate that they also affect specific native alternative 5'ss, especially for suppressor PRP8 D1549N. A strong suppressor at the unstructured N-terminus of SNRNP200, N18K, indicates a novel role for this region. By examining distinct changes in the splicing of native genes, examining double mutants between suppressors, comparing these new suppressors to previously identified splicing suppressors from yeast, and mapping conserved suppressor residues onto cryoEM structural models of assembling human spliceosomes, we conclude that there are multiple interactions at multiple stages in spliceosome assembly responsible for maintaining the initial 5'ss identified by U1snRNA for entry into the catalytic core.
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Affiliation(s)
- Catiana H Cartwright-Acar
- Department of MCD Biology and The Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, CA 95060, USA
| | - Kenneth Osterhoudt
- Department of MCD Biology and The Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, CA 95060, USA
| | - Jessie M N G L Suzuki
- Department of MCD Biology and The Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, CA 95060, USA
| | - Destiny R Gomez
- Department of MCD Biology and The Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, CA 95060, USA
| | - Sol Katzman
- Genomics Institute, University of California Santa Cruz, Santa Cruz, CA 95060, USA
| | - Alan M Zahler
- Department of MCD Biology and The Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, CA 95060, USA
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4
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Vanson S, Li Y, Wood RD, Doublié S. Probing the structure and function of polymerase θ helicase-like domain. DNA Repair (Amst) 2022; 116:103358. [PMID: 35753097 PMCID: PMC10329254 DOI: 10.1016/j.dnarep.2022.103358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/09/2022] [Accepted: 06/09/2022] [Indexed: 11/19/2022]
Abstract
DNA Polymerase θ is the key actuator of the recently identified double-strand break repair pathway, theta-mediated end joining (TMEJ). It is the only known polymerase to have a 3-domain architecture containing an independently functional family A DNA polymerase tethered by a long central region to an N-terminal helicase-like domain (HLD). Full-length polymerase θ and the isolated HLD hydrolyze ATP in the presence of DNA, but no processive DNA duplex unwinding has been observed. Based on sequence and structure conservation, the HLD is classified as a member of helicase superfamily II and, more specifically, the Ski2-like family. The specific subdomain composition and organization most closely resemble that of archaeal DNA repair helicases Hel308 and Hjm. The underlying structural basis as to why the HLD is not able to processively unwind duplex DNA, despite its similarity to bona fide helicases, remains elusive. Activities of the HLD include ATP hydrolysis, protein displacement, and annealing of complementary DNA. These observations have led to speculation about the role of the HLD within the context of double-strand break repair via TMEJ, such as removal of single-stranded DNA binding proteins like RPA and RAD51 and microhomology alignment. This review summarizes the structural classification and organization of the polymerase θ HLD and its homologs and explores emerging data on its biochemical activities. We conclude with a simple, speculative model for the HLD's role in TMEJ.
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Affiliation(s)
- Scott Vanson
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave, Burlington, VT 05405, USA
| | - Yuzhen Li
- Department of Epigenetics & Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, TX 77230, USA
| | - Richard D Wood
- Department of Epigenetics & Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, TX 77230, USA.
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave, Burlington, VT 05405, USA.
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5
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Bao J, Zhang Y, Zhang L, Wang X. Effects of maternal exposure to PFOA on testes of male offspring mice. CHEMOSPHERE 2021; 272:129585. [PMID: 33465609 DOI: 10.1016/j.chemosphere.2021.129585] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/30/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
This study was conducted to explore the effects of maternal exposure to perfluorooctanoic acid (PFOA) on testicular development of male offspring mice. 20 pregnant Kunming mice were randomly divided into control group and PFOA exposure group with 10 mice of each. In PFOA exposure group, pregnant mice were given 5 mg/kg BW PFOA daily by gavage during gestation. Male offspring mice were killed to separate serum and collect testis at postpartum day 21, then tested the experimental indicators. The results showed that compared with control group, the content of PFOA in the serum of PFOA-exposed mice increased significantly and testosterone content is significantly reduced. Histological observations revealed architectural damages in testis in PFOA exposed groups and the apoptosis was increased. Transcriptome sequencing results showed that the U4/U6 snRNA coding genes snu13 and prp19 complex coding genes HSP73 were up-regulated and the U5 snRNA coding genes Brr2, Prp8 and EJC/TREX coding THOC genes were down-regulated after PFOA exposure Real-time PCR confirmed this result. These results indicate that the exposure of pregnant mice to perfluorooctanoic acid will have a damaging effect on the development of testes in male offspring mice, which may be due to blocked activation of the shear body, changes in structural functions, and inability to perform shear functions.
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Affiliation(s)
- Jialu Bao
- College of Traditional Chinese Veterinary Medicine, Hebei Agricultural University, Baoding, 071001, China
| | - Yan Zhang
- College of Traditional Chinese Veterinary Medicine, Hebei Agricultural University, Baoding, 071001, China
| | - Linchao Zhang
- College of Traditional Chinese Veterinary Medicine, Hebei Agricultural University, Baoding, 071001, China
| | - Xiaodan Wang
- College of Traditional Chinese Veterinary Medicine, Hebei Agricultural University, Baoding, 071001, China.
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6
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Absmeier E, Vester K, Ghane T, Burakovskiy D, Milon P, Imhof P, Rodnina MV, Santos KF, Wahl MC. Long-range allostery mediates cooperative adenine nucleotide binding by the Ski2-like RNA helicase Brr2. J Biol Chem 2021; 297:100829. [PMID: 34048711 PMCID: PMC8220420 DOI: 10.1016/j.jbc.2021.100829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/18/2021] [Accepted: 05/24/2021] [Indexed: 11/17/2022] Open
Abstract
Brr2 is an essential Ski2-like RNA helicase that exhibits a unique structure among the spliceosomal helicases. Brr2 harbors a catalytically active N-terminal helicase cassette and a structurally similar but enzymatically inactive C-terminal helicase cassette connected by a linker region. Both cassettes contain a nucleotide-binding pocket, but it is unclear whether nucleotide binding in these two pockets is related. Here we use biophysical and computational methods to delineate the functional connectivity between the cassettes and determine whether occupancy of one nucleotide-binding site may influence nucleotide binding at the other cassette. Our results show that Brr2 exhibits high specificity for adenine nucleotides, with both cassettes binding ADP tighter than ATP. Adenine nucleotide affinity for the inactive C-terminal cassette is more than two orders of magnitude higher than that of the active N-terminal cassette, as determined by slow nucleotide release. Mutations at the intercassette surfaces and in the connecting linker diminish the affinity of adenine nucleotides for both cassettes. Moreover, we found that abrogation of nucleotide binding at the C-terminal cassette reduces nucleotide binding at the N-terminal cassette 70 Å away. Molecular dynamics simulations identified structural communication lines that likely mediate these long-range allosteric effects, predominantly across the intercassette interface. Together, our results reveal intricate networks of intramolecular interactions in the complex Brr2 RNA helicase, which fine-tune its nucleotide affinities and which could be exploited to regulate enzymatic activity during splicing.
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Affiliation(s)
- Eva Absmeier
- Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Karen Vester
- Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Tahereh Ghane
- Computational Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Dmitry Burakovskiy
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Pohl Milon
- Centre for Research and Innovation, Health Sciences Faculty, Universidad Peruana de Ciencias Aplicadas, Lima, Peru
| | - Petra Imhof
- Computational Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Karine F Santos
- Structural Biochemistry, Freie Universität Berlin, Berlin, Germany.
| | - Markus C Wahl
- Structural Biochemistry, Freie Universität Berlin, Berlin, Germany; Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany.
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7
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Kück U, Schmitt O. The Chloroplast Trans-Splicing RNA-Protein Supercomplex from the Green Alga Chlamydomonas reinhardtii. Cells 2021; 10:cells10020290. [PMID: 33535503 PMCID: PMC7912774 DOI: 10.3390/cells10020290] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/27/2022] Open
Abstract
In eukaryotes, RNA trans-splicing is a significant RNA modification process for the end-to-end ligation of exons from separately transcribed primary transcripts to generate mature mRNA. So far, three different categories of RNA trans-splicing have been found in organisms within a diverse range. Here, we review trans-splicing of discontinuous group II introns, which occurs in chloroplasts and mitochondria of lower eukaryotes and plants. We discuss the origin of intronic sequences and the evolutionary relationship between chloroplast ribonucleoprotein complexes and the nuclear spliceosome. Finally, we focus on the ribonucleoprotein supercomplex involved in trans-splicing of chloroplast group II introns from the green alga Chlamydomonas reinhardtii. This complex has been well characterized genetically and biochemically, resulting in a detailed picture of the chloroplast ribonucleoprotein supercomplex. This information contributes substantially to our understanding of the function of RNA-processing machineries and might provide a blueprint for other splicing complexes involved in trans- as well as cis-splicing of organellar intron RNAs.
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8
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Molecular Mechanism Underlying Inhibition of Intrinsic ATPase Activity in a Ski2-like RNA Helicase. Structure 2019; 28:236-243.e3. [PMID: 31859026 DOI: 10.1016/j.str.2019.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/06/2019] [Accepted: 11/22/2019] [Indexed: 11/20/2022]
Abstract
RNA-dependent NTPases can act as RNA/RNA-protein remodeling enzymes and typically exhibit low NTPase activity in the absence of RNA/RNA-protein substrates. How futile intrinsic NTP hydrolysis is prevented is frequently not known. The ATPase/RNA helicase Brr2 belongs to the Ski2-like family of nucleic acid-dependent NTPases and is an integral component of the spliceosome. Comprehensive nucleotide binding and hydrolysis studies are not available for a member of the Ski2-like family. We present crystal structures of Chaetomium thermophilum Brr2 in the apo, ADP-bound, and ATPγS-bound states, revealing nucleotide-induced conformational changes and a hitherto unknown ATPγS binding mode. Our results in conjunction with Brr2 structures in other molecular contexts reveal multiple molecular mechanisms that contribute to the inhibition of intrinsic ATPase activity, including an N-terminal region that restrains the RecA-like domains in an open conformation and exclusion of an attacking water molecule, and suggest how RNA substrate binding can lead to ATPase stimulation.
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9
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Structural and functional analyses of the spliceosome requires a multi-disciplinary approach. Methods 2017; 125:1-2. [PMID: 28780959 DOI: 10.1016/j.ymeth.2017.07.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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10
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Abstract
Proteins and RNA are often found in ribonucleoprotein particles (RNPs), where they function in cellular processes to synthesize proteins (the ribosome), chemically modify RNAs (small nucleolar RNPs), splice pre-mRNAs (the spliceosome), and, on a larger scale, sequester RNAs, degrade them, or process them (P bodies, Cajal bodies, and nucleoli). Each RNA–protein interaction is a story in itself, as both molecules can change conformation, compete for binding sites, and regulate cellular functions. Recent studies of Xist long non-coding RNP, the U4/5/6 tri-small nuclear RNP complex, and an activated state of a spliceosome reveal new features of RNA interactions with proteins, and, although their stories are incomplete, they are already fascinating.
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Affiliation(s)
- Kathleen B Hall
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO, 63110, USA
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11
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Absmeier E, Santos KF, Wahl MC. Functions and regulation of the Brr2 RNA helicase during splicing. Cell Cycle 2016; 15:3362-3377. [PMID: 27792457 DOI: 10.1080/15384101.2016.1249549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Pre-mRNA splicing entails the stepwise assembly of an inactive spliceosome, its catalytic activation, splicing catalysis and spliceosome disassembly. Transitions in this reaction cycle are accompanied by compositional and conformational rearrangements of the underlying RNA-protein interaction networks, which are driven and controlled by 8 conserved superfamily 2 RNA helicases. The Ski2-like helicase, Brr2, provides the key remodeling activity during spliceosome activation and is additionally implicated in the catalytic and disassembly phases of splicing, indicating that Brr2 needs to be tightly regulated during splicing. Recent structural and functional analyses have begun to unravel how Brr2 regulation is established via multiple layers of intra- and inter-molecular mechanisms. Brr2 has an unusual structure, including a long N-terminal region and a catalytically inactive C-terminal helicase cassette, which can auto-inhibit and auto-activate the enzyme, respectively. Both elements are essential, also serve as protein-protein interaction devices and the N-terminal region is required for stable Brr2 association with the tri-snRNP, tri-snRNP stability and retention of U5 and U6 snRNAs during spliceosome activation in vivo. Furthermore, a C-terminal region of the Prp8 protein, comprising consecutive RNase H-like and Jab1/MPN-like domains, can both up- and down-regulate Brr2 activity. Biochemical studies revealed an intricate cross-talk among the various cis- and trans-regulatory mechanisms. Comparison of isolated Brr2 to electron cryo-microscopic structures of yeast and human U4/U6•U5 tri-snRNPs and spliceosomes indicates how some of the regulatory elements exert their functions during splicing. The various modulatory mechanisms acting on Brr2 might be exploited to enhance splicing fidelity and to regulate alternative splicing.
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Affiliation(s)
- Eva Absmeier
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany
| | - Karine F Santos
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany
| | - Markus C Wahl
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany.,b Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography , Berlin , Germany
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12
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Mayerle M, Guthrie C. Prp8 retinitis pigmentosa mutants cause defects in the transition between the catalytic steps of splicing. RNA (NEW YORK, N.Y.) 2016; 22:793-809. [PMID: 26968627 PMCID: PMC4836653 DOI: 10.1261/rna.055459.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/11/2016] [Indexed: 05/14/2023]
Abstract
Pre-mRNA splicing must occur with high fidelity and efficiency for proper gene expression. The spliceosome uses DExD/H box helicases to promote on-pathway interactions while simultaneously minimizing errors. Prp8 and Snu114, an EF2-like GTPase, regulate the activity of the Brr2 helicase, promoting RNA unwinding by Brr2 at appropriate points in the splicing cycle and repressing it at others. Mutations linked to retinitis pigmentosa (RP), a disease that causes blindness in humans, map to the Brr2 regulatory region of Prp8. Previous in vitro studies of homologous mutations in Saccharomyces cerevisiaes how that Prp8-RP mutants cause defects in spliceosome activation. Here we show that a subset of RP mutations in Prp8 also causes defects in the transition between the first and second catalytic steps of splicing. Though Prp8-RP mutants do not cause defects in splicing fidelity, they result in an overall decrease in splicing efficiency. Furthermore, genetic analyses link Snu114 GTP/GDP occupancy to Prp8-dependent regulation of Brr2. Our results implicate the transition between the first and second catalytic steps as a critical place in the splicing cycle where Prp8-RP mutants influence splicing efficiency. The location of the Prp8-RP mutants, at the "hinge" that links the Prp8 Jab1-MPN regulatory "tail" to the globular portion of the domain, suggests that these Prp8-RP mutants inhibit regulated movement of the Prp8 Jab1/MPN domain into the Brr2 RNA binding channel to transiently inhibit Brr2. Therefore, in Prp8-linked RP, disease likely results not only from defects in spliceosome assembly and activation, but also because of defects in splicing catalysis.
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Affiliation(s)
- Megan Mayerle
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California 94143, USA
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California 94143, USA
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13
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Ledoux S, Guthrie C. Retinitis Pigmentosa Mutations in Bad Response to Refrigeration 2 (Brr2) Impair ATPase and Helicase Activity. J Biol Chem 2016; 291:11954-65. [PMID: 27072132 DOI: 10.1074/jbc.m115.710848] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Indexed: 11/06/2022] Open
Abstract
Brr2 is an RNA-dependent ATPase required to unwind the U4/U6 snRNA duplex during spliceosome assembly. Mutations within the ratchet helix of the Brr2 RNA binding channel result in a form of degenerative human blindness known as retinitis pigmentosa (RP). The biochemical consequences of these mutations on Brr2's RNA binding, helicase, and ATPase activity have not yet been characterized. Therefore, we identified the largest construct of Brr2 that is soluble in vitro, which truncates the first 247 amino acids of the N terminus (Δ247-Brr2), to characterize the effects of the RP mutations on Brr2 activity. The Δ247-Brr2 RP mutants exhibit a gradient of severity of weakened RNA binding, reduced helicase activity, and reduced ATPase activity compared with wild type Δ247-Brr2. The globular C-terminal Jab1/Mpn1-like domain of Prp8 increases the ability of Δ247-Brr2 to bind the U4/U6 snRNA duplex at high pH and increases Δ247-Brr2's RNA-dependent ATPase activity and the extent of RNA unwinding. However, this domain of Prp8 does not differentially affect the Δ247-Brr2 RP mutants compared with the wild type Δ247-Brr2. When stimulated by Prp8, wild type Δ247-Brr2 is able to unwind long stable duplexes in vitro, and even the RP mutants capable of binding RNA with tight affinity are incapable of fully unwinding short duplex RNAs. Our data suggest that the RP mutations within the ratchet helix impair Brr2 translocation through RNA helices.
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Affiliation(s)
- Sarah Ledoux
- From the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Christine Guthrie
- From the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
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14
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Gao X, Jin Q, Jiang C, Li Y, Li C, Liu H, Kang Z, Xu JR. FgPrp4 Kinase Is Important for Spliceosome B-Complex Activation and Splicing Efficiency in Fusarium graminearum. PLoS Genet 2016; 12:e1005973. [PMID: 27058959 PMCID: PMC4825928 DOI: 10.1371/journal.pgen.1005973] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/11/2016] [Indexed: 12/23/2022] Open
Abstract
PRP4 encodes the only kinase among the spliceosome components. Although it is an essential gene in the fission yeast and other eukaryotic organisms, the Fgprp4 mutant was viable in the wheat scab fungus Fusarium graminearum. Deletion of FgPRP4 did not block intron splicing but affected intron splicing efficiency in over 60% of the F. graminearum genes. The Fgprp4 mutant had severe growth defects and produced spontaneous suppressors that were recovered in growth rate. Suppressor mutations were identified in the PRP6, PRP31, BRR2, and PRP8 orthologs in nine suppressor strains by sequencing analysis with candidate tri-snRNP component genes. The Q86K mutation in FgMSL1 was identified by whole genome sequencing in suppressor mutant S3. Whereas two of the suppressor mutations in FgBrr2 and FgPrp8 were similar to those characterized in their orthologs in yeasts, suppressor mutations in Prp6 and Prp31 orthologs or FgMSL1 have not been reported. Interestingly, four and two suppressor mutations identified in FgPrp6 and FgPrp31, respectively, all are near the conserved Prp4-phosphorylation sites, suggesting that these mutations may have similar effects with phosphorylation by Prp4 kinase. In FgPrp31, the non-sense mutation at R464 resulted in the truncation of the C-terminal 130 aa region that contains all the conserved Prp4-phosphorylation sites. Deletion analysis showed that the N-terminal 310-aa rich in SR residues plays a critical role in the localization and functions of FgPrp4. We also conducted phosphoproteomics analysis with FgPrp4 and identified S289 as the phosphorylation site that is essential for its functions. These results indicated that FgPrp4 is critical for splicing efficiency but not essential for intron splicing, and FgPrp4 may regulate pre-mRNA splicing by phosphorylation of other components of the tri-snRNP although itself may be activated by phosphorylation at S289.
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Affiliation(s)
- Xuli Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Qiaojun Jin
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Yang Li
- Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Chaohui Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Jin-Rong Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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15
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Cornilescu G, Didychuk AL, Rodgers ML, Michael LA, Burke JE, Montemayor EJ, Hoskins AA, Butcher SE. Structural Analysis of Multi-Helical RNAs by NMR-SAXS/WAXS: Application to the U4/U6 di-snRNA. J Mol Biol 2016; 428:777-789. [PMID: 26655855 PMCID: PMC4790120 DOI: 10.1016/j.jmb.2015.11.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 11/25/2015] [Accepted: 11/30/2015] [Indexed: 01/17/2023]
Abstract
NMR and SAXS (small-angle X-ray scattering)/WAXS (wide-angle X-ray scattering) are highly complementary approaches for the analysis of RNA structure in solution. Here we describe an efficient NMR-SAXS/WAXS approach for structural investigation of multi-helical RNAs. We illustrate this approach by determining the overall fold of a 92-nt 3-helix junction from the U4/U6 di-snRNA. The U4/U6 di-snRNA is conserved in eukaryotes and is part of the U4/U6.U5 tri-snRNP, a large ribonucleoprotein complex that comprises a major subunit of the assembled spliceosome. Helical orientations can be determined by X-ray scattering data alone, but the addition of NMR RDC (residual dipolar coupling) restraints improves the structure models. RDCs were measured in two different external alignment media and also by magnetic susceptibility anisotropy. The resulting alignment tensors are collinear, which is a previously noted problem for nucleic acids. Including WAXS data in the calculations produces models with significantly better fits to the scattering data. In solution, the U4/U6 di-snRNA forms a 3-helix junction with a planar Y-shaped structure and has no detectable tertiary interactions. Single-molecule Förster resonance energy transfer data support the observed topology. A comparison with the recently determined cryo-electron microscopy structure of the U4/U6.U5 tri-snRNP illustrates how proteins scaffold the RNA and dramatically alter the geometry of the U4/U6 3-helix junction.
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Affiliation(s)
- Gabriel Cornilescu
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Allison L Didychuk
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Margaret L Rodgers
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Lauren A Michael
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Jordan E Burke
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Eric J Montemayor
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA.
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16
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De I, Schmitzová J, Pena V. The organization and contribution of helicases to RNA splicing. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:259-74. [PMID: 26874649 DOI: 10.1002/wrna.1331] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 12/27/2022]
Abstract
Splicing is an essential step of gene expression. It occurs in two consecutive chemical reactions catalyzed by a large protein-RNA complex named the spliceosome. Assembled on the pre-mRNA substrate from five small nuclear proteins, the spliceosome acts as a protein-controlled ribozyme to catalyze the two reactions and finally dissociates into its components, which are re-used for a new round of splicing. Upon following this cyclic pathway, the spliceosome undergoes numerous intermediate stages that differ in composition as well as in their internal RNA-RNA and RNA-protein contacts. The driving forces and control mechanisms of these remodeling processes are provided by specific molecular motors called RNA helicases. While eight spliceosomal helicases are present in all organisms, higher eukaryotes contain five additional ones potentially required to drive a more intricate splicing pathway and link it to an RNA metabolism of increasing complexity. Spliceosomal helicases exhibit a notable structural diversity in their accessory domains and overall architecture, in accordance with the diversity of their task-specific functions. This review summarizes structure-function knowledge about all spliceosomal helicases, including the latter five, which traditionally are treated separately from the conserved ones. The implications of the structural characteristics of helicases for their functions, as well as for their structural communication within the multi-subunits environment of the spliceosome, are pointed out.
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Affiliation(s)
- Inessa De
- Macromolecular Crystallography Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jana Schmitzová
- Macromolecular Crystallography Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Vladimir Pena
- Macromolecular Crystallography Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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17
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Absmeier E, Wollenhaupt J, Mozaffari-Jovin S, Becke C, Lee CT, Preussner M, Heyd F, Urlaub H, Lührmann R, Santos KF, Wahl MC. The large N-terminal region of the Brr2 RNA helicase guides productive spliceosome activation. Genes Dev 2015; 29:2576-87. [PMID: 26637280 PMCID: PMC4699386 DOI: 10.1101/gad.271528.115] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/13/2015] [Indexed: 01/06/2023]
Abstract
In this study, Absmeier et al. used a combination of X-ray crystallography, cross-linking/mass spectrometry, and in vivo and in vitro biochemical functional investigations to investigate the structural organization, functions, and molecular mechanisms of the NTR of the Brr2 helicase. The findings reveal molecular mechanisms that prevent premature and unproductive tri-snRNP disruption and suggest novel regulation of Brr2-dependent splicing. The Brr2 helicase provides the key remodeling activity for spliceosome catalytic activation, during which it disrupts the U4/U6 di-snRNP (small nuclear RNA protein), and its activity has to be tightly regulated. Brr2 exhibits an unusual architecture, including an ∼500-residue N-terminal region, whose functions and molecular mechanisms are presently unknown, followed by a tandem array of structurally similar helicase units (cassettes), only the first of which is catalytically active. Here, we show by crystal structure analysis of full-length Brr2 in complex with a regulatory Jab1/MPN domain of the Prp8 protein and by cross-linking/mass spectrometry of isolated Brr2 that the Brr2 N-terminal region encompasses two folded domains and adjacent linear elements that clamp and interconnect the helicase cassettes. Stepwise N-terminal truncations led to yeast growth and splicing defects, reduced Brr2 association with U4/U6•U5 tri-snRNPs, and increased ATP-dependent disruption of the tri-snRNP, yielding U4/U6 di-snRNP and U5 snRNP. Trends in the RNA-binding, ATPase, and helicase activities of the Brr2 truncation variants are fully rationalized by the crystal structure, demonstrating that the N-terminal region autoinhibits Brr2 via substrate competition and conformational clamping. Our results reveal molecular mechanisms that prevent premature and unproductive tri-snRNP disruption and suggest novel principles of Brr2-dependent splicing regulation.
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Affiliation(s)
- Eva Absmeier
- Laboratory of Structural Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Jan Wollenhaupt
- Laboratory of Structural Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Sina Mozaffari-Jovin
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Christian Becke
- Laboratory of Structural Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Chung-Tien Lee
- Research Group Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany; Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Georg-August-Universität, D-37099 Göttingen, Germany
| | - Marco Preussner
- Laboratory of RNA Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Florian Heyd
- Laboratory of RNA Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Henning Urlaub
- Research Group Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany; Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Georg-August-Universität, D-37099 Göttingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Karine F Santos
- Laboratory of Structural Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
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18
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RNA-Binding Proteins: Splicing Factors and Disease. Biomolecules 2015; 5:893-909. [PMID: 25985083 PMCID: PMC4496701 DOI: 10.3390/biom5020893] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 04/22/2015] [Accepted: 04/29/2015] [Indexed: 12/12/2022] Open
Abstract
Pre-mRNA splicing is mediated by interactions of the Core Spliceosome and an array of accessory RNA binding proteins with cis-sequence elements. Splicing is a major regulatory component in higher eukaryotes. Disruptions in splicing are a major contributor to human disease. One in three hereditary disease alleles are believed to cause aberrant splicing. Hereditary disease alleles can alter splicing by disrupting a splicing element, creating a toxic RNA, or affecting splicing factors. One of the challenges of medical genetics is identifying causal variants from the thousands of possibilities discovered in a clinical sequencing experiment. Here we review the basic biochemistry of splicing, the mechanisms of splicing mutations, the methods for identifying splicing mutants, and the potential of therapeutic interventions.
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