1
|
Yeh FL, Chang SL, Ahmed GR, Liu HI, Tung L, Yeh CS, Lanier LS, Maeder C, Lin CM, Tsai SC, Hsiao WY, Chang WH, Chang TH. Activation of Prp28 ATPase by phosphorylated Npl3 at a critical step of spliceosome remodeling. Nat Commun 2021; 12:3082. [PMID: 34035302 PMCID: PMC8149812 DOI: 10.1038/s41467-021-23459-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 04/29/2021] [Indexed: 11/10/2022] Open
Abstract
Splicing, a key step in the eukaryotic gene-expression pathway, converts precursor messenger RNA (pre-mRNA) into mRNA by excising introns and ligating exons. This task is accomplished by the spliceosome, a macromolecular machine that must undergo sequential conformational changes to establish its active site. Each of these major changes requires a dedicated DExD/H-box ATPase, but how these enzymes are activated remain obscure. Here we show that Prp28, a yeast DEAD-box ATPase, transiently interacts with the conserved 5' splice-site (5'SS) GU dinucleotide and makes splicing-dependent contacts with the U1 snRNP protein U1C, and U4/U6.U5 tri-snRNP proteins, Prp8, Brr2, and Snu114. We further show that Prp28's ATPase activity is potentiated by the phosphorylated Npl3, but not the unphosphorylated Npl3, thus suggesting a strategy for regulating DExD/H-box ATPases. We propose that Npl3 is a functional counterpart of the metazoan-specific Prp28 N-terminal region, which can be phosphorylated and serves as an anchor to human spliceosome.
Collapse
Affiliation(s)
- Fu-Lung Yeh
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | | | | | - Hsin-I Liu
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Luh Tung
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chung-Shu Yeh
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Leah Stands Lanier
- Department of Biology, Washington and Lee University, Lexington, VA, USA
| | - Corina Maeder
- Department of Chemistry, Trinity University, San Antonio, TX, USA
| | - Che-Min Lin
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Shu-Chun Tsai
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Wan-Yi Hsiao
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Wei-Hau Chang
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
| | | |
Collapse
|
2
|
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: 93] [Impact Index Per Article: 15.5] [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.
Collapse
|
3
|
Abstract
Group II introns are self-splicing catalytic RNAs found in bacteria and the organelles of fungi and plants. They are thought to share a common ancestor with the spliceosome, which catalyzes the removal of nuclear introns from pre-mRNAs in eukaryotes. Recent structural and biochemical evidence supports the hypothesis that the spliceosome has a catalytic RNA core homologous to that found in group II introns. The crystal structure of a eukaryotic group IIB intron was recently determined and reveals the architecture of a branched lariat RNA that is also formed by the spliceosome. Here we describe the active site components of this intron and propose a model for RNA splicing involving dynamic base triples in the catalytic triad. Based on this structure, we draw analogies to the U2/U6 snRNA pairing and RNA-protein interactions that form in the active site of the spliceosome.
Collapse
Affiliation(s)
- Jessica K Peters
- a Department of Chemistry and Biochemistry ; University of California, San Diego ; La Jolla , CA USA
| | - Navtej Toor
- a Department of Chemistry and Biochemistry ; University of California, San Diego ; La Jolla , CA USA
| |
Collapse
|
4
|
Boesler C, Rigo N, Anokhina MM, Tauchert MJ, Agafonov DE, Kastner B, Urlaub H, Ficner R, Will CL, Lührmann R. A spliceosome intermediate with loosely associated tri-snRNP accumulates in the absence of Prp28 ATPase activity. Nat Commun 2016; 7:11997. [PMID: 27377154 PMCID: PMC4935976 DOI: 10.1038/ncomms11997] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/20/2016] [Indexed: 11/17/2022] Open
Abstract
The precise role of the spliceosomal DEAD-box protein Prp28 in higher eukaryotes remains unclear. We show that stable tri-snRNP association during pre-catalytic spliceosomal B complex formation is blocked by a dominant-negative hPrp28 mutant lacking ATPase activity. Complexes formed in the presence of ATPase-deficient hPrp28 represent a novel assembly intermediate, the pre-B complex, that contains U1, U2 and loosely associated tri-snRNP and is stalled before disruption of the U1/5′ss base pairing interaction, consistent with a role for hPrp28 in the latter. Pre-B and B complexes differ structurally, indicating that stable tri-snRNP integration is accompanied by substantial rearrangements in the spliceosome. Disruption of the U1/5′ss interaction alone is not sufficient to bypass the block by ATPase-deficient hPrp28, suggesting hPrp28 has an additional function at this stage of splicing. Our data provide new insights into the function of Prp28 in higher eukaryotes, and the requirements for stable tri-snRNP binding during B complex formation. The assembly of the splicesome involves several distinct stages that require the sequential action of DExD/H-box RNA helicases. Here, the authors uncover a new intermediate, the pre-B complex, that accumulates in the presence of an inactive form of the DEAD-box protein Prp28.
Collapse
Affiliation(s)
- Carsten Boesler
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Norbert Rigo
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Maria M Anokhina
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Marcel J Tauchert
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Dmitry E Agafonov
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Berthold Kastner
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.,Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany
| | - Cindy L Will
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| |
Collapse
|
5
|
Tauchert MJ, Ficner R. Structural analysis of the spliceosomal RNA helicase Prp28 from the thermophilic eukaryote Chaetomium thermophilum. Acta Crystallogr F Struct Biol Commun 2016; 72:409-16. [PMID: 27139834 PMCID: PMC4854570 DOI: 10.1107/s2053230x16006038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/11/2016] [Indexed: 11/10/2022] Open
Abstract
Prp28 (pre-mRNA-splicing ATP-dependent RNA helicase 28) is a spliceosomal DEAD-box helicase which is involved in two steps of spliceosome assembly. It is required for the formation of commitment complex 2 in an ATP-independent manner as well as for the formation of the pre-catalytic spliceosome, which in contrast is ATP-dependent. During the latter step, Prp28 is crucial for the integration of the U4/U6·U5 tri-snRNP since it displaces the U1 snRNP and allows the U6 snRNP to base-pair with the 5'-splice site. Here, the crystal structure of Prp28 from the thermophilic fungus Chaetomium thermophilum is reported at 3.2 Å resolution and is compared with the available structures of homologues.
Collapse
Affiliation(s)
- Marcel J. Tauchert
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| |
Collapse
|
6
|
Suthar MK, Purva M, Maherchandani S, Kashyap SK. Identification and in silico analysis of cattle DExH/D box RNA helicases. SPRINGERPLUS 2016; 5:25. [PMID: 26783509 PMCID: PMC4705078 DOI: 10.1186/s40064-015-1640-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 12/20/2015] [Indexed: 12/16/2022]
Abstract
The helicases are motor proteins participating
in a range of nucleic acid metabolisms. RNA helicase families are characterized by the presence of conserved motifs. This article reports a comprehensive in silico analysis of Bos taurus DExH/D helicase members. Bovine helicases were identified using the helicase domain sequences including 38 DDX (DEAD box) and 16 DHX (DEAH box) members. Signature motifs were used for the validation of these proteins. Putative sub cellular localization and phylogenetic relationship for these RNA helicases were established. Comparative analysis of these proteins with human DDX and DHX members was carried out. These bovine helicase have been assigned putative physiological functions. Present study of cattle DExH/D helicase will provides an invaluable source for the detailed biochemical and physiological research on these members.
Collapse
Affiliation(s)
- Manish Kumar Suthar
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary & Animal Sciences, Bikaner, Rajasthan 334001 India
| | - Mukul Purva
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary & Animal Sciences, Bikaner, Rajasthan 334001 India
| | - Sunil Maherchandani
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary & Animal Sciences, Bikaner, Rajasthan 334001 India
| | - Sudhir Kumar Kashyap
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary & Animal Sciences, Bikaner, Rajasthan 334001 India
| |
Collapse
|
7
|
Boesler C, Rigo N, Agafonov DE, Kastner B, Urlaub H, Will CL, Lührmann R. Stable tri-snRNP integration is accompanied by a major structural rearrangement of the spliceosome that is dependent on Prp8 interaction with the 5' splice site. RNA (NEW YORK, N.Y.) 2015; 21:1993-2005. [PMID: 26385511 PMCID: PMC4604437 DOI: 10.1261/rna.053991.115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 08/21/2015] [Indexed: 05/22/2023]
Abstract
Exon definition is the predominant initial spliceosome assembly pathway in higher eukaryotes, but it remains much less well-characterized compared to the intron-defined assembly pathway. Addition in trans of an excess of 5'ss containing RNA to a splicing reaction converts a 37S exon-defined complex, formed on a single exon RNA substrate, into a 45S B-like spliceosomal complex with stably integrated U4/U6.U5 tri-snRNP. This 45S complex is compositonally and structurally highly similar to an intron-defined spliceosomal B complex. Stable tri-snRNP integration during B-like complex formation is accompanied by a major structural change as visualized by electron microscopy. The changes in structure and stability during transition from a 37S to 45S complex can be induced in affinity-purified cross-exon complexes by adding solely the 5'ss RNA oligonucleotide. This conformational change does not require the B-specific proteins, which are recruited during this stabilization process, or site-specific phosphorylation of hPrp31. Instead it is triggered by the interaction of U4/U6.U5 tri-snRNP components with the 5'ss sequence, most importantly between Prp8 and nucleotides at the exon-intron junction. These studies provide novel insights into the conversion of a cross-exon to cross-intron organized spliceosome and also shed light on the requirements for stable tri-snRNP integration during B complex formation.
Collapse
Affiliation(s)
- Carsten Boesler
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Norbert Rigo
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Dmitry E Agafonov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Berthold Kastner
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Cindy L Will
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| |
Collapse
|
8
|
Möhlmann S, Mathew R, Neumann P, Schmitt A, Lührmann R, Ficner R. Structural and functional analysis of the human spliceosomal DEAD-box helicase Prp28. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:1622-30. [PMID: 24914973 PMCID: PMC4051504 DOI: 10.1107/s1399004714006439] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/23/2014] [Indexed: 11/10/2022]
Abstract
The DEAD-box protein Prp28 is essential for pre-mRNA splicing as it plays a key role in the formation of an active spliceosome. Prp28 participates in the release of the U1 snRNP from the 5'-splice site during association of the U5·U4/U6 tri-snRNP, which is a crucial step in the transition from a pre-catalytic spliceosome to an activated spliceosome. Here, it is demonstrated that the purified helicase domain of human Prp28 (hPrp28ΔN) binds ADP, whereas binding of ATP and ATPase activity could not be detected. ATP binding could not be observed for purified full-length hPrp28 either, but within an assembled spliceosomal complex hPrp28 gains ATP-binding activity. In order to understand the structural basis for the ATP-binding deficiency of isolated hPrp28, the crystal structure of hPrp28ΔN was determined at 2.0 Å resolution. In the crystal the helicase domain adopts a wide-open conformation, as the two RecA-like domains are extraordinarily displaced from the productive ATPase conformation. Binding of ATP is hindered by a closed conformation of the P-loop, which occupies the space required for the γ-phosphate of ATP.
Collapse
Affiliation(s)
- Sina Möhlmann
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Rebecca Mathew
- Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, 37077 Göttingen, Germany
| | - Piotr Neumann
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Andreas Schmitt
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Reinhard Lührmann
- Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg, 37077 Göttingen, Germany
| | - Ralf Ficner
- Molecular Structural Biology, Georg-August-University Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| |
Collapse
|
9
|
Price AM, Görnemann J, Guthrie C, Brow DA. An unanticipated early function of DEAD-box ATPase Prp28 during commitment to splicing is modulated by U5 snRNP protein Prp8. RNA (NEW YORK, N.Y.) 2014; 20:46-60. [PMID: 24231520 PMCID: PMC3866644 DOI: 10.1261/rna.041970.113] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The stepwise assembly of the highly dynamic spliceosome is guided by RNA-dependent ATPases of the DEAD-box family, whose regulation is poorly understood. In the canonical assembly model, the U4/U6.U5 triple snRNP binds only after joining of the U1 and, subsequently, U2 snRNPs to the intron-containing pre-mRNA. Catalytic activation requires the exchange of U6 for U1 snRNA at the 5' splice site, which is promoted by the DEAD-box protein Prp28. Because Prp8, an integral U5 snRNP protein, is thought to be a central regulator of DEAD-box proteins, we conducted a targeted search in Prp8 for cold-insensitive suppressors of a cold-sensitive Prp28 mutant, prp28-1. We identified a cluster of suppressor mutations in an N-terminal bromodomain-like sequence of Prp8. To identify the precise defect in prp28-1 strains that is suppressed by the Prp8 alleles, we analyzed spliceosome assembly in vivo and in vitro. Surprisingly, in the prp28-1 strain, we observed a block not only to spliceosome activation but also to one of the earliest steps of assembly, formation of the ATP-independent commitment complex 2 (CC2). The Prp8 suppressor partially corrected both the early assembly and later activation defects of prp28-1, supporting a role for this U5 snRNP protein in both the ATP-independent and ATP-dependent functions of Prp28. We conclude that the U5 snRNP has a role in the earliest events of assembly, prior to its stable incorporation into the spliceosome.
Collapse
Affiliation(s)
- Argenta M. Price
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
| | - Janina Görnemann
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
- Corresponding authorsE-mail E-mail
| | - David A. Brow
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA
- Corresponding authorsE-mail E-mail
| |
Collapse
|
10
|
Yang F, Wang XY, Zhang ZM, Pu J, Fan YJ, Zhou J, Query CC, Xu YZ. Splicing proofreading at 5' splice sites by ATPase Prp28p. Nucleic Acids Res 2013; 41:4660-70. [PMID: 23462954 PMCID: PMC3632134 DOI: 10.1093/nar/gkt149] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Fidelity and efficiency of pre-mRNA splicing are critical for generating functional mRNAs, but how such accuracy in 5′ splice site (SS) selection is attained is not fully clear. Through a series of yeast genetic screens, we isolated alleles of prp28 that improve splicing of suboptimal 5′SS substrates, demonstrating that WT-Prp28p proofreads, and consequently rejects, poor 5′SS. Prp28p is thought to facilitate the disruption of 5′SS–U1 snRNA pairing to allow for 5′SS–U6 snRNA pairing in the catalytic spliceosome; unexpectedly, 5′SS proofreading by Prp28p is dependent on competition with the stability of the 5′SS:U6 duplex, but not the 5′SS:U1 duplex. E404K, the strongest prp28 allele containing a mutation located in the linker region between adenosine triphosphatase (ATPase) subdomains, exhibited lower RNA-binding activity and enhanced splicing of suboptimal substrates before first-step catalysis, suggesting that decreased Prp28p activity allows longer time for suboptimal 5′SS substrates to pair with U6 snRNA and thereby reduces splicing fidelity. Residue E404 is critical for providing high splicing activity, demonstrated here in both yeast and Drosophila cells. Thus, the subdomain linker in Prp28p plays important roles both in splicing efficiency across species and in proofreading of 5′SS.
Collapse
Affiliation(s)
- Fei Yang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Chang TH, Tung L, Yeh FL, Chen JH, Chang SL. Functions of the DExD/H-box proteins in nuclear pre-mRNA splicing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:764-74. [PMID: 23454554 DOI: 10.1016/j.bbagrm.2013.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/05/2013] [Accepted: 02/13/2013] [Indexed: 01/09/2023]
Abstract
In eukaryotes, many genes are transcribed as precursor messenger RNAs (pre-mRNAs) that contain exons and introns, the latter of which must be removed and exons ligated to form the mature mRNAs. This process is called pre-mRNA splicing, which occurs in the nucleus. Although the chemistry of pre-mRNA splicing is identical to that of the self-splicing Group II introns, hundreds of proteins and five small nuclear RNAs (snRNAs), U1, U2, U4, U5, and U6, are essential for executing pre-mRNA splicing. Spliceosome, arguably the most complex cellular machine made up of all those proteins and snRNAs, is responsible for carrying out pre-mRNA splicing. In contrast to the transcription and the translation machineries, spliceosome is formed anew onto each pre-mRNA and undergoes a series of highly coordinated reconfigurations to form the catalytic center. This amazing process is orchestrated by a number of DExD/H-proteins that are the focus of this article, which aims to review the field in general and to project the exciting challenges and opportunities ahead. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
Collapse
|
12
|
Kershaw CJ, Barrass JD, Beggs JD, O'Keefe RT. Mutations in the U5 snRNA result in altered splicing of subsets of pre-mRNAs and reduced stability of Prp8. RNA (NEW YORK, N.Y.) 2009; 15:1292-304. [PMID: 19447917 PMCID: PMC2704078 DOI: 10.1261/rna.1347409] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The U5 snRNA loop 1 aligns the 5' and 3' exons for ligation during the second step of pre-mRNA splicing. U5 is intimately associated with Prp8, which mediates pre-mRNA repositioning within the catalytic core of the spliceosome and interacts directly with U5 loop 1. The genome-wide effect of three U5 loop 1 mutants has been assessed by microarray analysis. These mutants exhibited impaired and improved splicing of subsets of pre-mRNAs compared to wild-type U5. Analysis of pre-mRNAs that accumulate revealed a change in base prevalence at specific positions near the splice sites. Analysis of processed pre-mRNAs exhibiting mRNA accumulation revealed a bias in base prevalence at one position within the 5' exon. While U5 loop 1 can interact with some of these positions the base bias is not directly related to sequence changes in loop 1. All positions that display a bias in base prevalence are at or next to positions known to interact with Prp8. Analysis of Prp8 in the presence of the three U5 loop 1 mutants revealed that the most severe mutant displayed reduced Prp8 stability. Depletion of U5 snRNA in vivo also resulted in reduced Prp8 stability. Our data suggest that certain mutations in U5 loop 1 perturb the stability of Prp8 and may affect interactions of Prp8 with a subset of pre-mRNAs influencing their splicing. Therefore, the integrity of U5 is important for the stability of Prp8 during splicing and provides one possible explanation for why U5 loop 1 and Prp8 are so highly conserved.
Collapse
Affiliation(s)
- Christopher J Kershaw
- Faculty of Life Sciences, The University of Manchester, Manchester M139PT, United Kingdom
| | | | | | | |
Collapse
|
13
|
Pomeranz Krummel DA, Oubridge C, Leung AKW, Li J, Nagai K. Crystal structure of human spliceosomal U1 snRNP at 5.5 A resolution. Nature 2009; 458:475-80. [PMID: 19325628 PMCID: PMC2673513 DOI: 10.1038/nature07851] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 02/04/2009] [Indexed: 12/03/2022]
|
14
|
Abstract
Ribonucleoproteins (RNPs) mediate key cellular functions such as gene expression and its regulation. Whereas most RNP enzymes are stable in composition and harbor preformed active sites, the spliceosome, which removes noncoding introns from precursor messenger RNAs (pre-mRNAs), follows fundamentally different strategies. In order to provide both accuracy to the recognition of reactive splice sites in the pre-mRNA and flexibility to the choice of splice sites during alternative splicing, the spliceosome exhibits exceptional compositional and structural dynamics that are exploited during substrate-dependent complex assembly, catalytic activation, and active site remodeling.
Collapse
Affiliation(s)
- Markus C Wahl
- Makromolekulare Röntgenkristallographie, Max-Planck-Institut für biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany.
| | | | | |
Collapse
|
15
|
Pena V, Rozov A, Fabrizio P, Lührmann R, Wahl MC. Structure and function of an RNase H domain at the heart of the spliceosome. EMBO J 2008; 27:2929-40. [PMID: 18843295 PMCID: PMC2580788 DOI: 10.1038/emboj.2008.209] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 09/18/2008] [Indexed: 11/09/2022] Open
Abstract
Precursor-messenger RNA (pre-mRNA) splicing encompasses two sequential transesterification reactions in distinct active sites of the spliceosome that are transiently established by the interplay of small nuclear (sn) RNAs and spliceosomal proteins. Protein Prp8 is an active site component but the molecular mechanisms, by which it might facilitate splicing catalysis, are unknown. We have determined crystal structures of corresponding portions of yeast and human Prp8 that interact with functional regions of the pre-mRNA, revealing a phylogenetically conserved RNase H fold, augmented by Prp8-specific elements. Comparisons to RNase H-substrate complexes suggested how an RNA encompassing a 5'-splice site (SS) could bind relative to Prp8 residues, which on mutation, suppress splice defects in pre-mRNAs and snRNAs. A truncated RNase H-like active centre lies next to a known contact region of the 5'SS and directed mutagenesis confirmed that this centre is a functional hotspot. These data suggest that Prp8 employs an RNase H domain to help assemble and stabilize the spliceosomal catalytic core, coordinate the activities of other splicing factors and possibly participate in chemical catalysis of splicing.
Collapse
Affiliation(s)
- Vladimir Pena
- Abteilung Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
- Abteilung Zelluläre Biochemie, AG Röntgenkristallographie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
| | - Alexey Rozov
- Abteilung Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
| | - Patrizia Fabrizio
- Abteilung Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
| | - Reinhard Lührmann
- Abteilung Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
| | - Markus C Wahl
- Abteilung Zelluläre Biochemie, AG Röntgenkristallographie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
- Universitätsmedizin, Georg-August-Universität, Göttingen, Germany
| |
Collapse
|
16
|
Schwer B. A conformational rearrangement in the spliceosome sets the stage for Prp22-dependent mRNA release. Mol Cell 2008; 30:743-54. [PMID: 18570877 DOI: 10.1016/j.molcel.2008.05.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 04/16/2008] [Accepted: 05/02/2008] [Indexed: 12/16/2022]
Abstract
An essential step in pre-mRNA splicing is the release of the mRNA product from the spliceosome. The DEAH box RNA helicase Prp22 catalyzes mRNA release by remodeling contacts within the spliceosome that involve the U5 snRNP. Spliceosome disassembly requires a segment of more than 13 ribonucleotides downstream of the 3' splice site. I show here by site-specific crosslinking and RNase H protection that Prp22 interacts with the mRNA downstream of the exon-exon junction prior to mRNA release. The findings support a model for Prp22-catalyzed mRNA release from the spliceosome wherein a rearrangement that accompanies the second transesterification step deposits Prp22 on the mRNA downstream of the exon-exon junction. Bound to its target RNA, the 3'-->5' helicase acts to disrupt mRNA/U5 snRNP contacts, thereby liberating the mRNA from the spliceosome.
Collapse
Affiliation(s)
- Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA.
| |
Collapse
|
17
|
McAlinden A, Havlioglu N, Liang L, Davies SR, Sandell LJ. Alternative splicing of type II procollagen exon 2 is regulated by the combination of a weak 5' splice site and an adjacent intronic stem-loop cis element. J Biol Chem 2005; 280:32700-11. [PMID: 16076844 DOI: 10.1074/jbc.m505940200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alternative splicing of the type II procollagen gene (COL2A1) is developmentally regulated during chondrogenesis. Chondroprogenitor cells produce the type IIA procollagen isoform by splicing (including) exon 2 during pre-mRNA processing, whereas differentiated chondrocytes synthesize the type IIB procollagen isoform by exon 2 skipping (exclusion). Using a COL2A1 mini-gene and chondrocytes at various stages of differentiation, we identified a non-classical consensus splicing sequence in intron 2 adjacent to the 5' splice site, which is essential in regulating exon 2 splicing. RNA mapping confirmed this region contains secondary structure in the form of a stem-loop. Mutational analysis identified three cis elements within the conserved double-stranded stem region that are functional only in the context of the natural weak 5' splice site of exon 2; they are 1) a uridine-rich enhancer element in all cell types tested except differentiated chondrocytes; 2) an adenine-rich silencer element, and 3) an enhancer cis element functional in the context of secondary structure. This is the first report identifying key cis elements in the COL2A1 gene that modulate the cell type-specific alternative splicing switch of exon 2 during cartilage development.
Collapse
Affiliation(s)
- Audrey McAlinden
- Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, Missouri 63110, USA.
| | | | | | | | | |
Collapse
|
18
|
Abstract
Pre-messenger RNA (pre-mRNA) splicing is a central step in gene expression. Lying between transcription and protein synthesis, pre-mRNA splicing removes sequences (introns) that would otherwise disrupt the coding potential of intron-containing transcripts. This process takes place in the nucleus, catalyzed by a large RNA-protein complex called the spliceosome. Prp8p, one of the largest and most highly conserved of nuclear proteins, occupies a central position in the catalytic core of the spliceosome, and has been implicated in several crucial molecular rearrangements that occur there. Recently, Prp8p has also come under the spotlight for its role in the inherited human disease, Retinitis Pigmentosa.Prp8 is unique, having no obvious homology to other proteins; however, using bioinformatical analysis we reveal the presence of a conserved RNA recognition motif (RRM), an MPN/JAB domain and a putative nuclear localization signal (NLS). Here, we review biochemical and genetical data, mostly related to the human and yeast proteins, that describe Prp8's central role within the spliceosome and its molecular interactions during spliceosome formation, as splicing proceeds, and in post-splicing complexes.
Collapse
Affiliation(s)
- Richard J Grainger
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, United Kingdom
| | | |
Collapse
|
19
|
Turner IA, Norman CM, Churcher MJ, Newman AJ. Roles of the U5 snRNP in spliceosome dynamics and catalysis. Biochem Soc Trans 2005; 32:928-31. [PMID: 15506927 DOI: 10.1042/bst0320928] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Most protein-coding genes in eukaryotes are interrupted by non-coding intervening sequences (introns), which must be precisely removed from primary gene transcripts (pre-mRNAs) before translation of the message into protein. Intron removal by pre-mRNA splicing occurs in the nucleus and is catalysed by complex ribonucleoprotein machines called spliceosomes. These molecular machines consist of several small nuclear RNA molecules and their associated proteins [together termed snRNP (small nuclear ribonucleoprotein) particles], plus multiple accessory factors. Of particular interest are the U2, U5 and U6 snRNPs, which play crucial roles in the catalytic steps of splicing. In the present review, we summarize our current understanding of the role played by the protein components of the U5 snRNP in pre-mRNA splicing, which include some of the largest and most highly conserved nuclear proteins.
Collapse
Affiliation(s)
- I A Turner
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | | | | | | |
Collapse
|
20
|
Kameoka S, Duque P, Konarska MM. p54(nrb) associates with the 5' splice site within large transcription/splicing complexes. EMBO J 2004; 23:1782-91. [PMID: 15057275 PMCID: PMC394241 DOI: 10.1038/sj.emboj.7600187] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2003] [Accepted: 03/04/2004] [Indexed: 11/09/2022] Open
Abstract
The functional coupling of transcription and splicing has been reported both in vivo and in vitro, but the molecular mechanisms governing these interactions remain largely unknown. Here we show that p54(nrb), a transcription/splicing factor, associates with the 5' splice site (SS) within large complexes present in HeLa cell nuclear extracts, in which the hyperphosphorylated form of RNA polymerase II (RNAPIIO) is associated with U1 or U1 and U2 snRNPs. These RNAPIIO-snRNP complexes also contain other transcription/splicing factors, such as PSF and TLS, as well as transcription factors that interact with RNAPIIO during elongation, including P-TEFb, TAT-SF1 and TFIIF. The presence of these factors in functional elongation complexes, demonstrated using an immobilized DNA template assay, strongly suggests that the RNAPIIO-snRNP complexes reflect physiologically relevant interactions between the transcription and splicing machineries. Our finding that both p54(nrb) and PSF, which bind the C-terminal domain of the largest subunit of RNAPII, can interact directly with the 5' SS indicates that these factors may mediate contacts between RNAPII and snRNPs during the coupled transcription/splicing process.
Collapse
Affiliation(s)
- Sei Kameoka
- The Rockefeller University, New York, NY, USA
| | - Paula Duque
- The Rockefeller University, New York, NY, USA
| | | |
Collapse
|
21
|
Abstract
Introns are removed from precursor messenger RNAs in the cell nucleus by a large ribonucleoprotein complex called the spliceosome. The spliceosome contains five subcomplexes called snRNPs, each with one RNA and several protein components. Interactions of the snRNPs with each other and the intron are highly dynamic, changing in an ordered progression throughout the splicing process. This allosteric cascade of interactions is programmed into the RNA and protein components of the spliceosome, and is driven by a family of DExD/H-box RNA-dependent ATPases. The dependence of cascade progression on multiple intron-recognition events likely serves to enforce the accuracy of splicing. Here, the progression of the allosteric cascade from the first recognition event to the first catalytic step of splicing is reviewed.
Collapse
Affiliation(s)
- David A Brow
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1532, USA.
| |
Collapse
|
22
|
Vincent K, Wang Q, Jay S, Hobbs K, Rymond BC. Genetic interactions with CLF1 identify additional pre-mRNA splicing factors and a link between activators of yeast vesicular transport and splicing. Genetics 2003; 164:895-907. [PMID: 12871902 PMCID: PMC1462608 DOI: 10.1093/genetics/164.3.895] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Clf1 is a conserved spliceosome assembly factor composed predominately of TPR repeats. Here we show that the TPR elements are not functionally equivalent, with the amino terminus of Clf1 being especially sensitive to change. Deletion and add-back experiments reveal that the splicing defect associated with TPR removal results from the loss of TPR-specific sequence information. Twelve mutants were found that show synthetic growth defects when combined with an allele that lacks TPR2 (i.e., clf1Delta2). The identified genes encode the Mud2, Ntc20, Prp16, Prp17, Prp19, Prp22, and Syf2 splicing factors and four proteins without established contribution to splicing (Bud13, Cet1, Cwc2, and Rds3). Each synthetic lethal with clf1Delta2 (slc) mutant is splicing defective in a wild-type CLF1 background. In addition to the splicing factors, SSD1, BTS1, and BET4 were identified as dosage suppressors of clf1Delta2 or selected slc mutants. These results support Clf1 function through multiple stages of the spliceosome cycle, identify additional genes that promote cellular mRNA maturation, and reveal a link between Rab/Ras GTPase activation and the process of pre-mRNA splicing.
Collapse
Affiliation(s)
- Kevin Vincent
- Department of Biology, University of Kentucky, Lexington, Kentucky 40506-0225, USA
| | | | | | | | | |
Collapse
|
23
|
Abstract
Nucleic acid helicases are characterized by the presence of the helicase domain containing eight motifs. The sequence of the helicase domain is used to classify helicases into families. To identify members of the DEAD and DEAH families of human RNA helicases, we used the helicase domain sequences to search the nonredundant peptide sequence database. We report the identification of 36 and 14 members of the DEAD and DEAH families of putative RNA helicases, including several novel genes. The gene symbol DDX had been used previously for both DEAD- and DEAH-box families. We have now adopted DDX and DHX symbols to denote DEAD- and DEAH-box families, respectively. Members of human DDX and DHX families of putative RNA helicases play roles in differentiation and carcinogenesis.
Collapse
Affiliation(s)
- Mohamed Abdelhaleem
- Division of Haematopathology, Department of Paediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
| | | | | |
Collapse
|
24
|
Liu ZR. p68 RNA helicase is an essential human splicing factor that acts at the U1 snRNA-5' splice site duplex. Mol Cell Biol 2002; 22:5443-50. [PMID: 12101238 PMCID: PMC133941 DOI: 10.1128/mcb.22.15.5443-5450.2002] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Modulation of the interaction between U1 snRNP and the 5' splice site (5'ss) is a key event that governs 5'ss recognition and spliceosome assembly. Using the methylene blue-mediated cross-linking method (Z. R. Liu, A. M. Wilkie, M. J. Clemens, and C. W. Smith, RNA 2:611-621, 1996), a 65-kDa protein (p65) was shown to interact with the U1-5'ss duplex during spliceosome assembly (Z. R. Liu, B. Sargueil, and C. W. Smith, Mol. Cell. Biol. 18:6910-6920, 1998). In this report, p65 was identified as p68 RNA helicase and shown to be essential for in vitro pre-mRNA splicing. Depletion of endogenous p68 RNA helicase does not affect the loading of the U1 snRNP to the 5'ss during early stage of splicing. However, dissociation of the U1 from the 5'ss is largely inhibited. The data suggest that p68 RNA helicase functions in destabilizing the U1-5'ss interactions. Furthermore, depletion of p68 RNA helicase arrested spliceosome assembly at the prespliceosome stage, suggesting that p68 may play a role in the transition from prespliceosome to spliceosome.
Collapse
Affiliation(s)
- Zhi-Ren Liu
- Program in Cell & Molecular Biosciences, Department of Animal Sciences, Auburn University, 210 Upchurch Hall, Auburn, AL 36849, USA.
| |
Collapse
|
25
|
Valdez BC, Perlaky L, Henning D. Expression, cellular localization, and enzymatic activities of RNA helicase II/Gu(beta). Exp Cell Res 2002; 276:249-63. [PMID: 12027455 DOI: 10.1006/excr.2002.5538] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
RNA helicase II/Gu (RH-II/Gu) is a nucleolar DEAD-box protein that unwinds double-stranded RNA and introduces secondary structure to a single-stranded RNA. We recently identified its paralogue, RH-II/Gu(beta), in contrast to the original RH-II/Gu(alpha). Their similar intron-exon structures on chromosome 10 suggest gene duplication. To determine functional differences, their expression, localization, and enzymatic activities were compared. RH-II/Gu(alpha) is expressed two- to threefold more than RH-II/Gu(beta) in most tissues. Both proteins localize to nucleoli, suggesting roles in ribosomal RNA production, but RH-II/Gu(beta) also localizes to nuclear speckles containing splicing factor SC35, suggesting possible involvement in pre-mRNA splicing. The C-terminus responsible for nuclear speckle localization of RH-II/Gu(beta) contains an arginine-serine-rich domain present in some RNA splicing proteins. In vitro assays show weaker ATPase and RNA helicase activities of RH-II/Gu(beta). RH-II/Gu(alpha) unwinds RNA substrate with a 21- or 34-nt duplex and 5' overhangs, but RH-II/Gu(beta) unwinds only the shorter duplex. Although RH-II/Gu(beta) has no RNA folding activity, it catalyzes formation of an RNA complex with unidentified structure, which is not observed when assayed with a mixture of the two enzymes. Instead, the presence of RH-II/Gu(beta) stimulates RH-II/Gu(alpha) unwinding activity. Our data suggest distinct and complex regulation of expression of the two paralogues with nonredundant gene products.
Collapse
MESH Headings
- Active Transport, Cell Nucleus/drug effects
- Active Transport, Cell Nucleus/genetics
- Amino Acid Sequence
- Animals
- Cell Compartmentation/genetics
- Cell Nucleolus/enzymology
- Cell Nucleolus/genetics
- Cell Nucleus/enzymology
- Cells, Cultured
- DEAD-box RNA Helicases
- Dactinomycin/pharmacology
- Eukaryotic Cells/enzymology
- Gene Expression Regulation, Enzymologic/genetics
- Gene Expression Regulation, Neoplastic/genetics
- Humans
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Molecular Sequence Data
- Nuclear Matrix/enzymology
- Nuclear Matrix/genetics
- Nucleic Acid Synthesis Inhibitors/pharmacology
- RNA Helicases/genetics
- RNA Helicases/metabolism
- RNA Splicing/genetics
- RNA, Double-Stranded/drug effects
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Ribosomal/genetics
- Tumor Cells, Cultured/enzymology
Collapse
Affiliation(s)
- Benigno C Valdez
- Department of Pharmacology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
| | | | | |
Collapse
|
26
|
Lund M, Kjems J. Defining a 5' splice site by functional selection in the presence and absence of U1 snRNA 5' end. RNA (NEW YORK, N.Y.) 2002; 8:166-179. [PMID: 11911363 PMCID: PMC1370240 DOI: 10.1017/s1355838202010786] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Pre-mRNA splicing in metazoans is mainly specified by sequences at the termini of introns. We have selected functional 5' splice sites from randomized intron sequences through repetitive rounds of in vitro splicing in HeLa cell nuclear extract. The consensus sequence obtained after one round of selection in normal extract closely resembled the consensus of natural occurring 5' splice sites, suggesting that the selection pressures in vitro and in vivo are similar. After three rounds of selection under competitive splicing conditions, the base pairing potential to the U1 snRNA increased, yielding a G100%U100%R94%A67%G89%U76%R83% intronic consensus sequence. Surprisingly, a nearly identical consensus sequence was obtained when the selection was performed in nuclear extract containing U1 snRNA with a deleted 5' end, suggesting that other factors than the U1 snRNA are involved in 5' splice site recognition. The importance of a consecutive complementarity between the 5' splice site and the U1 snRNA was analyzed systematically in the natural range for in vitro splicing efficiency and complex formation. Extended complementarity was inhibitory to splicing at a late step in spliceosome assembly when pre-mRNA substrates were incubated in normal extract, but favorable for splicing under competitive splicing conditions or in the presence of truncated U1 snRNA where transition from complex A to complex B occurred more rapidly. This suggests that stable U1 snRNA binding is advantageous for assembly of commitment complexes, but inhibitory for the entry of the U4/U6.U5 tri-snRNP, probably due to a delayed release of the U1 snRNP.
Collapse
Affiliation(s)
- Mette Lund
- Department of Molecular and Structural Biology, University of Aarhus, Denmark
| | | |
Collapse
|
27
|
Newnham CM, Query CC. The ATP requirement for U2 snRNP addition is linked to the pre-mRNA region 5' to the branch site. RNA (NEW YORK, N.Y.) 2001; 7:1298-309. [PMID: 11565751 PMCID: PMC1370173 DOI: 10.1017/s1355838201010561] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Association of U2 snRNP with the pre-mRNA branch region is the first ATP-dependent step in spliceosome assembly. The basis of this energy dependence is not known. Previously, we identified minimal intron-derived substrates that form complexes with U2 independent of ATP. Here, we identify the intron region linked to the ATP dependence of this step by comparing these substrates to longer RNAs that recapitulate the ATP requirement. This region needed to impose ATP dependence lies immediately 5' to the branch site. Sequences ranging from 6 to 14 nt yield a near linear inhibitory effect on efficiency of complex formation with U2 snRNP, with 18 nt yielding near maximal ATP dependence. This region is not protected prior to U2 addition, and RNase H targeting of the region within nuclear extract converts an ATP-dependent substrate into an ATP-independent one. Within this region, there is no sequence specificity linked with the ATP requirement, as neither a specific sequence is needed, nor even nucleobases. These data and the results of other modifications suggest models in which the 18-nt region is a target for interactions with U2 snRNP in an ATP-bound or -activated conformation.
Collapse
Affiliation(s)
- C M Newnham
- Department of Cell Biology, Albert Einstein College of Medicine. New York, New York 10461-1975, USA
| | | |
Collapse
|