101
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Suzuki H, Takeuchi M, Sugiyama A, Alam AK, Vu LT, Sekiyama Y, Dam HC, Ohki SY, Tsukahara T. Alternative splicing produces structural and functional changes in CUGBP2. BMC BIOCHEMISTRY 2012; 13:6. [PMID: 22433174 PMCID: PMC3368720 DOI: 10.1186/1471-2091-13-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 03/20/2012] [Indexed: 02/04/2023]
Abstract
Background CELF/Bruno-like proteins play multiple roles, including the regulation of alternative splicing and translation. These RNA-binding proteins contain two RNA recognition motif (RRM) domains at the N-terminus and another RRM at the C-terminus. CUGBP2 is a member of this family of proteins that possesses several alternatively spliced exons. Results The present study investigated the expression of exon 14, which is an alternatively spliced exon and encodes the first half of the third RRM of CUGBP2. The ratio of exon 14 skipping product (R3δ) to its inclusion was reduced in neuronal cells induced from P19 cells and in the brain. Although full length CUGBP2 and the CUGBP2 R3δ isoforms showed a similar effect on the inclusion of the smooth muscle (SM) exon of the ACTN1 gene, these isoforms showed an opposite effect on the skipping of exon 11 in the insulin receptor gene. In addition, examination of structural changes in these isoforms by molecular dynamics simulation and NMR spectrometry suggested that the third RRM of R3δ isoform was flexible and did not form an RRM structure. Conclusion Our results suggest that CUGBP2 regulates the splicing of ACTN1 and insulin receptor by different mechanisms. Alternative splicing of CUGBP2 exon 14 contributes to the regulation of the splicing of the insulin receptor. The present findings specifically show how alternative splicing events that result in three-dimensional structural changes in CUGBP2 can lead to changes in its biological activity.
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Affiliation(s)
- Hitoshi Suzuki
- Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan.
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102
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Chang J, Schwer B, Shuman S. Structure-function analysis and genetic interactions of the yeast branchpoint binding protein Msl5. Nucleic Acids Res 2012; 40:4539-52. [PMID: 22287628 PMCID: PMC3378887 DOI: 10.1093/nar/gks049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Saccharomyces cerevisiae Msl5 (branchpoint binding protein) orchestrates spliceosome assembly by binding the branchpoint sequence 5′-UACUAAC and establishing cross intron-bridging interactions with other components of the splicing machinery. Reciprocal tandem affinity purifications verify that Msl5 exists in vivo as a heterodimer with Mud2 and that the Msl5–Mud2 complex is associated with the U1 snRNP. By gauging the ability of mutants of Msl5 to complement msl5Δ, we find that the Mud2-binding (amino acids 35–54) and putative Prp40-binding (PPxY100) elements of the Msl5 N-terminal domain are inessential, as are the C-terminal proline-rich domain (amino acids 382–476) and two zinc-binding CxxCxxxxHxxxxC motifs (amino acids 273–286 and 299–312). A subset of conserved branchpoint RNA-binding amino acids in the central KH-QUA2 domain (amino acids 146–269) are essential pairwise (Ile198–Arg190; Leu256–Leu259) or in trios (Leu169–Arg172–Leu176), whereas other pairs of RNA-binding residues are dispensable. We used our collection of viable Msl5 mutants to interrogate synthetic genetic interactions, in cis between the inessential structural elements of the Msl5 polypeptide and in trans between Msl5 and yeast splicing factors (Mud2, Nam8 and Tgs1) that are optional for vegetative growth. The results suggest a network of important but functionally buffered protein–protein and protein–RNA interactions between the Mud2–Msl5 complex at the branchpoint and the U1 snRNP at the 5′ splice site.
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Affiliation(s)
- Jonathan Chang
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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103
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Muto Y, Yokoyama S. Structural insight into RNA recognition motifs: versatile molecular Lego building blocks for biological systems. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:229-46. [PMID: 22278943 DOI: 10.1002/wrna.1107] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
'RNA recognition motifs (RRMs)' are common domain-folds composed of 80-90 amino-acid residues in eukaryotes, and have been identified in many cellular proteins. At first they were known as RNA binding domains. Through discoveries over the past 20 years, however, the RRMs have been shown to exhibit versatile molecular recognition activities and to behave as molecular Lego building blocks to construct biological systems. Novel RNA/protein recognition modes by RRMs are being identified, and more information about the molecular recognition by RRMs is becoming available. These RNA/protein recognition modes are strongly correlated with their biological significance. In this review, we would like to survey the recent progress on these versatile molecular recognition modules.
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Affiliation(s)
- Yutaka Muto
- Systems and Structural Biology Center, RIKEN, Tsurumi, Japan.
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105
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Franceschetti M, Bueno E, Wilson RA, Tucker SL, Gómez-Mena C, Calder G, Sesma A. Fungal virulence and development is regulated by alternative pre-mRNA 3'end processing in Magnaporthe oryzae. PLoS Pathog 2011; 7:e1002441. [PMID: 22194688 PMCID: PMC3240610 DOI: 10.1371/journal.ppat.1002441] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 11/01/2011] [Indexed: 12/21/2022] Open
Abstract
RNA-binding proteins play a central role in post-transcriptional mechanisms that control gene expression. Identification of novel RNA-binding proteins in fungi is essential to unravel post-transcriptional networks and cellular processes that confer identity to the fungal kingdom. Here, we carried out the functional characterisation of the filamentous fungus-specific RNA-binding protein RBP35 required for full virulence and development in the rice blast fungus. RBP35 contains an N-terminal RNA recognition motif (RRM) and six Arg-Gly-Gly tripeptide repeats. Immunoblots identified two RBP35 protein isoforms that show a steady-state nuclear localisation and bind RNA in vitro. RBP35 coimmunoprecipitates in vivo with Cleavage Factor I (CFI) 25 kDa, a highly conserved protein involved in polyA site recognition and cleavage of pre-mRNAs. Several targets of RBP35 have been identified using transcriptomics including 14-3-3 pre-mRNA, an important integrator of environmental signals. In Magnaporthe oryzae, RBP35 is not essential for viability but regulates the length of 3′UTRs of transcripts with developmental and virulence-associated functions. The Δrbp35 mutant is affected in the TOR (target of rapamycin) signaling pathway showing significant changes in nitrogen metabolism and protein secretion. The lack of clear RBP35 orthologues in yeast, plants and animals indicates that RBP35 is a novel auxiliary protein of the polyadenylation machinery of filamentous fungi. Our data demonstrate that RBP35 is the fungal equivalent of metazoan CFI 68 kDa and suggest the existence of 3′end processing mechanisms exclusive to the fungal kingdom. The rice blast fungus Magnaporthe oryzae is one of the most damaging diseases of cultivated rice worldwide and an emerging disease on wheat, impacting on global food security. We identify a M. oryzae virulence-deficient mutant defective in the production of a RNA-binding protein (called RBP35). Clear orthologues of RBP35 are absent in yeast, plants and metazoans. We find two RBP35 protein isoforms that localise in the nucleus and bind RNA. Notably, we demonstrate that RBP35 interacts in vivo with a highly conserved protein component of the eukaryotic polyadenylation machinery. We show that RBP35 present different diffusional properties in nuclei of distinct fungal structures, and consequently different protein/nucleic acid interactions. Further, we find that RBP35 regulates the length of 3′UTRs of transcripts with developmental and virulence-associated functions. We prove that the Δrbp35 mutant is affected in the TOR (target of rapamycin) signaling pathway showing significant changes in nitrogen metabolism and protein secretion. Nothing it is known about pre-mRNA 3′ end processing in filamentous fungi and our study suggest that their polyadenylation machinery differs from yeast and higher organisms. This study can provide new insights into the evolution of the pre-mRNA maturation and the regulation of gene expression in eukaryotes.
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Affiliation(s)
| | - Emilio Bueno
- Disease & Stress Biology Department, John Innes Centre, Norwich, United Kingdom
| | - Richard A. Wilson
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Sara L. Tucker
- Disease & Stress Biology Department, John Innes Centre, Norwich, United Kingdom
| | | | - Grant Calder
- Cell & Developmental Biology Department, John Innes Centre, Norwich, United Kingdom
| | - Ane Sesma
- Disease & Stress Biology Department, John Innes Centre, Norwich, United Kingdom
- * E-mail:
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Jung H, Lyons RE, Dinh H, Hurwood DA, McWilliam S, Mather PB. Transcriptomics of a giant freshwater prawn (Macrobrachium rosenbergii): de novo assembly, annotation and marker discovery. PLoS One 2011; 6:e27938. [PMID: 22174756 PMCID: PMC3234237 DOI: 10.1371/journal.pone.0027938] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 10/28/2011] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Giant freshwater prawn (Macrobrachium rosenbergii or GFP), is the most economically important freshwater crustacean species. However, as little is known about its genome, 454 pyrosequencing of cDNA was undertaken to characterise its transcriptome and identify genes important for growth. METHODOLOGY AND PRINCIPAL FINDINGS A collection of 787,731 sequence reads (244.37 Mb) obtained from 454 pyrosequencing analysis of cDNA prepared from muscle, ovary and testis tissues taken from 18 adult prawns was assembled into 123,534 expressed sequence tags (ESTs). Of these, 46% of the 8,411 contigs and 19% of 115,123 singletons possessed high similarity to sequences in the GenBank non-redundant database, with most significant (E value < 1e(-5)) contig (80%) and singleton (84%) matches occurring with crustacean and insect sequences. KEGG analysis of the contig open reading frames identified putative members of several biological pathways potentially important for growth. The top InterProScan domains detected included RNA recognition motifs, serine/threonine-protein kinase-like domains, actin-like families, and zinc finger domains. Transcripts derived from genes such as actin, myosin heavy and light chain, tropomyosin and troponin with fundamental roles in muscle development and construction were abundant. Amongst the contigs, 834 single nucleotide polymorphisms, 1198 indels and 658 simple sequence repeats motifs were also identified. CONCLUSIONS The M. rosenbergii transcriptome data reported here should provide an invaluable resource for improving our understanding of this species' genome structure and biology. The data will also instruct future functional studies to manipulate or select for genes influencing growth that should find practical applications in aquaculture breeding programs.
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Affiliation(s)
- Hyungtaek Jung
- Biogeosciences, Queensland University of Technology, Brisbane, Queensland, Australia.
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107
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Bauer WJ, Heath J, Jenkins JL, Kielkopf CL. Three RNA recognition motifs participate in RNA recognition and structural organization by the pro-apoptotic factor TIA-1. J Mol Biol 2011; 415:727-40. [PMID: 22154808 DOI: 10.1016/j.jmb.2011.11.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 10/03/2011] [Accepted: 11/22/2011] [Indexed: 01/10/2023]
Abstract
T-cell intracellular antigen-1 (TIA-1) regulates developmental and stress-responsive pathways through distinct activities at the levels of alternative pre-mRNA splicing and mRNA translation. The TIA-1 polypeptide contains three RNA recognition motifs (RRMs). The central RRM2 and C-terminal RRM3 associate with cellular mRNAs. The N-terminal RRM1 enhances interactions of a C-terminal Q-rich domain of TIA-1 with the U1-C splicing factor, despite linear separation of the domains in the TIA-1 sequence. Given the expanded functional repertoire of the RRM family, it was unknown whether TIA-1 RRM1 contributes to RNA binding as well as documented protein interactions. To address this question, we used isothermal titration calorimetry and small-angle X-ray scattering to dissect the roles of the TIA-1 RRMs in RNA recognition. Notably, the fas RNA exhibited two binding sites with indistinguishable affinities for TIA-1. Analyses of TIA-1 variants established that RRM1 was dispensable for binding AU-rich fas sites, yet all three RRMs were required to bind a polyU RNA with high affinity. Small-angle X-ray scattering analyses demonstrated a "V" shape for a TIA-1 construct comprising the three RRMs and revealed that its dimensions became more compact in the RNA-bound state. The sequence-selective involvement of TIA-1 RRM1 in RNA recognition suggests a possible role for RNA sequences in regulating the distinct functions of TIA-1. Further implications for U1-C recruitment by the adjacent TIA-1 binding sites of the fas pre-mRNA and the bent TIA-1 shape, which organizes the N- and C-termini on the same side of the protein, are discussed.
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Affiliation(s)
- William J Bauer
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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108
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Fouquet R, Martin F, Fajardo DS, Gault CM, Gómez E, Tseung CW, Policht T, Hueros G, Settles AM. Maize rough endosperm3 encodes an RNA splicing factor required for endosperm cell differentiation and has a nonautonomous effect on embryo development. THE PLANT CELL 2011; 23:4280-97. [PMID: 22138152 PMCID: PMC3269866 DOI: 10.1105/tpc.111.092163] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 09/30/2011] [Accepted: 11/18/2011] [Indexed: 05/18/2023]
Abstract
Endosperm and embryo development are coordinated via epigenetic regulation and signaling between these tissues. In maize (Zea mays), the endosperm-embryo signals are not known, but endosperm cellularization is a key event for embryos to form shoots and roots. We screened seed mutants for nonautonomous functions in endosperm and embryo development with genetically nonconcordant seeds and identified the recessive mutant rough endosperm3 (rgh3). The wild-type Rgh3 allele is required in the endosperm for embryos to develop and has an autonomous role in embryo and seedling development. Endosperm cell differentiation is defective in rgh3. Results from endosperm cell culture indicate that rgh3 mutants remain in a proliferative state through mid-seed development. Rgh3 encodes the maize U2AF(35) Related Protein (URP), an RNA splicing factor involved in both U2 and U12 splicing. The Rgh3 allele produces at least 19 alternative splice variants with only one isoform encoding a full-length ortholog to URP. The full-length RGH3α isoform localizes to the nucleolus and displays a speckled pattern within the nucleoplasm, and RGH3α colocalizes with U2AF(65). A survey of alternatively spliced transcripts found that, in the rgh3 mutant, a fraction of noncanonical splicing events are altered. Our findings suggest that differentiation of maize endosperm cell types is necessary for embryos to develop. The molecular cloning of Rgh3 suggests that alternative RNA splicing is needed for cell differentiation, development, and plant viability.
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Affiliation(s)
- Romain Fouquet
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Federico Martin
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Diego S. Fajardo
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Christine M. Gault
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Elisa Gómez
- Departamento de Biología Celular y Genética, Universidad de Alcalá, 28871 Alcalá de Henares (Madrid), Spain
| | - Chi-Wah Tseung
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Tyler Policht
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Gregorio Hueros
- Departamento de Biología Celular y Genética, Universidad de Alcalá, 28871 Alcalá de Henares (Madrid), Spain
| | - A. Mark Settles
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
- Address correspondence to
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MacKellar AL, Greenleaf AL. Cotranscriptional association of mRNA export factor Yra1 with C-terminal domain of RNA polymerase II. J Biol Chem 2011; 286:36385-95. [PMID: 21856751 PMCID: PMC3196081 DOI: 10.1074/jbc.m111.268144] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 07/28/2011] [Indexed: 11/06/2022] Open
Abstract
The unique C-terminal domain (CTD) of RNA polymerase II, composed of tandem heptad repeats of the consensus sequence YSPTSPS, is subject to differential phosphorylation throughout the transcription cycle. Several RNA processing factors have been shown to bind the phosphorylated CTD and use it to localize to nascent pre-mRNA during transcription. In Saccharomyces cerevisiae, the mRNA export protein Yra1 (ALY/RNA export factor in metazoa) cotranscriptionally associates with mRNA and delivers it to the nuclear pore complex for export to the cytoplasm. Here we report that Yra1 directly binds in vitro the hyperphosphorylated form of the CTD characteristic of elongating RNA polymerase II and contains a phospho-CTD-interacting domain within amino acids 18-184, which also include an "RNA recognition motif" (RRM) (residues 77-184). Using UV cross-linking, we showed that the RRM alone binds RNA, although a larger segment extending to the C terminus (amino acids 77-226) displayed stronger RNA binding activity. Although the RRM is implicated in both RNA and CTD binding, RRM point mutations separated these two functions. Both functions are important in vivo as RNA binding-defective or CTD binding-defective versions of Yra1 engendered growth and mRNA export defects. We also report the construction and characterization of a useful new temperature-sensitive YRA1 allele (R107A/F126A). Using ChIP, we demonstrated that removing the N-terminal 76 amino acids of Yra1 (all of the phospho-CTD-interacting domain up to the RRM) results in a 10-fold decrease in Yra1 recruitment to genes during elongation. These results indicate that the phospho-CTD is likely involved directly in the cotranscriptional recruitment of Yra1.
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Affiliation(s)
- April L. MacKellar
- From the Department of Biochemistry and Center for RNA Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Arno L. Greenleaf
- From the Department of Biochemistry and Center for RNA Biology, Duke University Medical Center, Durham, North Carolina 27710
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Callahan KE, Hickman AB, Jones CE, Ghirlando R, Furano AV. Polymerization and nucleic acid-binding properties of human L1 ORF1 protein. Nucleic Acids Res 2011; 40:813-27. [PMID: 21937507 PMCID: PMC3258132 DOI: 10.1093/nar/gkr728] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The L1 (LINE 1) retrotransposable element encodes two proteins, ORF1p and ORF2p. ORF2p is the L1 replicase, but the role of ORF1p is unknown. Mouse ORF1p, a coiled-coil-mediated trimer of ∼42-kDa monomers, binds nucleic acids and has nucleic acid chaperone activity. We purified human L1 ORF1p expressed in insect cells and made two findings that significantly advance our knowledge of the protein. First, in the absence of nucleic acids, the protein polymerizes under the very conditions (0.05 M NaCl) that are optimal for high (∼1 nM)-affinity nucleic acid binding. The non-coiled-coil C-terminal half mediates formation of the polymer, an active conformer that is instantly resolved to trimers, or multimers thereof, by nucleic acid. Second, the protein has a biphasic effect on mismatched double-stranded DNA, a proxy chaperone substrate. It protects the duplex from dissociation at 37°C before eventually melting it when largely polymeric. Therefore, polymerization of ORF1p seemingly affects its interaction with nucleic acids. Additionally, polymerization of ORF1p at its translation site could explain the heretofore-inexplicable phenomenon of cis preference-the favored retrotransposition of the actively translated L1 transcript, which is essential for L1 survival.
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Affiliation(s)
- Kathryn E Callahan
- The Laboratory of Molecular and Cellular Biology, National Institue of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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111
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Santiveri CM, Mirassou Y, Rico-Lastres P, Martínez-Lumbreras S, Pérez-Cañadillas JM. Pub1p C-terminal RRM domain interacts with Tif4631p through a conserved region neighbouring the Pab1p binding site. PLoS One 2011; 6:e24481. [PMID: 21931728 PMCID: PMC3169606 DOI: 10.1371/journal.pone.0024481] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 08/11/2011] [Indexed: 11/18/2022] Open
Abstract
Pub1p, a highly abundant poly(A)+ mRNA binding protein in Saccharomyces cerevisiae, influences the stability and translational control of many cellular transcripts, particularly under some types of environmental stresses. We have studied the structure, RNA and protein recognition modes of different Pub1p constructs by NMR spectroscopy. The structure of the C-terminal RRM domain (RRM3) shows a non-canonical N-terminal helix that packs against the canonical RRM fold in an original fashion. This structural trait is conserved in Pub1p metazoan homologues, the TIA-1 family, defining a new class of RRM-type domains that we propose to name TRRM (TIA-1 C-terminal domain-like RRM). Pub1p TRRM and the N-terminal RRM1-RRM2 tandem bind RNA with high selectivity for U-rich sequences, with TRRM showing additional preference for UA-rich ones. RNA-mediated chemical shift changes map to β-sheet and protein loops in the three RRMs. Additionally, NMR titration and biochemical in vitro cross-linking experiments determined that Pub1p TRRM interacts specifically with the N-terminal region (1-402) of yeast eIF4G1 (Tif4631p), very likely through the conserved Box1, a short sequence motif neighbouring the Pab1p binding site in Tif4631p. The interaction involves conserved residues of Pub1p TRRM, which define a protein interface that mirrors the Pab1p-Tif4631p binding mode. Neither protein nor RNA recognition involves the novel N-terminal helix, whose functional role remains unclear. By integrating these new results with the current knowledge about Pub1p, we proposed different mechanisms of Pub1p recruitment to the mRNPs and Pub1p-mediated mRNA stabilization in which the Pub1p/Tif4631p interaction would play an important role.
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Affiliation(s)
- Clara M. Santiveri
- Department of Biological Physical Chemistry, Instituto de Química-Física “Rocasolano”, CSIC, Madrid, Spain
| | - Yasmina Mirassou
- Department of Biological Physical Chemistry, Instituto de Química-Física “Rocasolano”, CSIC, Madrid, Spain
| | - Palma Rico-Lastres
- Department of Biological Physical Chemistry, Instituto de Química-Física “Rocasolano”, CSIC, Madrid, Spain
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David CJ, Boyne AR, Millhouse SR, Manley JL. The RNA polymerase II C-terminal domain promotes splicing activation through recruitment of a U2AF65-Prp19 complex. Genes Dev 2011; 25:972-83. [PMID: 21536736 DOI: 10.1101/gad.2038011] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pre-mRNA splicing is frequently coupled to transcription by RNA polymerase II (RNAPII). This coupling requires the C-terminal domain of the RNAPII largest subunit (CTD), although the underlying mechanism is poorly understood. Using a biochemical complementation assay, we previously identified an activity that stimulates CTD-dependent splicing in vitro. We purified this activity and found that it consists of a complex of two well-known splicing factors: U2AF65 and the Prp19 complex (PRP19C). We provide evidence that both U2AF65 and PRP19C are required for CTD-dependent splicing activation, that U2AF65 and PRP19C interact both in vitro and in vivo, and that this interaction is required for activation of splicing. Providing the link to the CTD, we show that U2AF65 binds directly to the phosphorylated CTD, and that this interaction results in increased recruitment of U2AF65 and PRP19C to the pre-mRNA. Our results not only provide a mechanism by which the CTD enhances splicing, but also describe unexpected interactions important for splicing and its coupling to transcription.
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Affiliation(s)
- Charles J David
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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113
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Gupta A, Gribskov M. The role of RNA sequence and structure in RNA--protein interactions. J Mol Biol 2011; 409:574-87. [PMID: 21514302 DOI: 10.1016/j.jmb.2011.04.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 02/07/2011] [Accepted: 04/04/2011] [Indexed: 11/17/2022]
Abstract
We investigate the sequence and structural properties of RNA--protein interaction sites in 211 RNA--protein chain pairs, the largest set of RNA--protein complexes analyzed to date. Statistical analysis confirms and extends earlier analyses made on smaller data sets. There are 24.6% of hydrogen bonds between RNA and protein that are nucleobase specific, indicating the importance of both nucleobase-specific and -nonspecific interactions. While there is no significant difference between RNA base frequencies in protein-binding and non-binding regions, distinct preferences for RNA bases, RNA structural states, protein residues, and protein secondary structure emerge when nucleobase-specific and -nonspecific interactions are considered separately. Guanine nucleobase and unpaired RNA structural states are significantly preferred in nucleobase-specific interactions; however, nonspecific interactions disfavor guanine, while still favoring unpaired RNA structural states. The opposite preferences of nucleobase-specific and -nonspecific interactions for guanine may explain discrepancies between earlier studies with regard to base preferences in RNA--protein interaction regions. Preferences for amino acid residues differ significantly between nucleobase-specific and -nonspecific interactions, with nonspecific interactions showing the expected bias towards positively charged residues. Irregular protein structures are strongly favored in interactions with the protein backbone, whereas there is little preference for specific protein secondary structure in either nucleobase-specific interaction or -nonspecific interaction. Overall, this study shows strong preferences for both RNA bases and RNA structural states in protein--RNA interactions, indicating their mutual importance in protein recognition.
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Affiliation(s)
- Aditi Gupta
- Department of Biological Sciences, Purdue University, Hockmeyer Hall of Structural Biology, West Lafayette, IN 47907, USA
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Gupta A, Kielkopf CL. Purification, crystallization and preliminary X-ray crystallographic analysis of a central domain of human splicing factor 1. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:486-90. [PMID: 21505248 PMCID: PMC3080157 DOI: 10.1107/s1744309111004623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 02/07/2011] [Indexed: 11/11/2022]
Abstract
Pre-mRNA splicing is an essential source of genetic diversity in eukaryotic organisms. In the early stages of splicing, splicing factor 1 (SF1) recognizes the pre-mRNA splice site as a complex with its partner, U2 auxiliary factor 65 kDa subunit (U2AF(65)). A central `mystery' domain of SF1 (SF1md) lacks detectable homology with known structures, yet is the region of highest phylogenetic sequence conservation among SF1 homologues. Here, steps towards determining the SF1md structure are described. Firstly, SF1md was expressed and purified. The presence of regular secondary structure was verified using circular dichroism spectroscopy and the SF1md protein was then crystallized. A native data set was collected and processed to 2.5 Å resolution. The SF1md crystals belonged to space group C2 and have most probable solvent contents of 64, 52 or 39% with three, four or five molecules per asymmetric unit, respectively. Mutually perpendicular peaks on the κ = 180° section of the self-rotation function support the presence of four molecules in the asymmetric unit.
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Affiliation(s)
- Ankit Gupta
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Clara L. Kielkopf
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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115
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Shen H, Zheng X, Luecke S, Green MR. The U2AF35-related protein Urp contacts the 3' splice site to promote U12-type intron splicing and the second step of U2-type intron splicing. Genes Dev 2011; 24:2389-94. [PMID: 21041408 DOI: 10.1101/gad.1974810] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The U2AF35-related protein Urp has been implicated previously in splicing of the major class of U2-type introns. Here we show that Urp is also required for splicing of the minor class of U12-type introns. Urp is recruited in an ATP-dependent fashion to the U12-type intron 3' splice site, where it promotes formation of spliceosomal complexes. Remarkably, Urp also contacts the 3' splice site of a U2-type intron, but in this case is specifically required for the second step of splicing. Thus, through recognition of a common splicing element, Urp facilitates distinct steps of U2- and U12-type intron splicing.
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Affiliation(s)
- Haihong Shen
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
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116
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Gupta A, Jenkins JL, Kielkopf CL. RNA induces conformational changes in the SF1/U2AF65 splicing factor complex. J Mol Biol 2011; 405:1128-38. [PMID: 21146534 PMCID: PMC3037027 DOI: 10.1016/j.jmb.2010.11.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 11/02/2010] [Accepted: 11/27/2010] [Indexed: 10/18/2022]
Abstract
Spliceosomes assemble on pre-mRNA splice sites through a series of dynamic ribonucleoprotein complexes, yet the nature of the conformational changes remains unclear. Splicing factor 1 (SF1) and U2 auxiliary factor (U2AF(65)) cooperatively recognize the 3' splice site during the initial stages of pre-mRNA splicing. Here, we used small-angle X-ray scattering to compare the molecular dimensions and ab initio shape restorations of SF1 and U2AF(65) splicing factors, as well as the SF1/U2AF(65) complex in the absence and presence of AdML (adenovirus major late) splice site RNAs. The molecular dimensions of the SF1/U2AF(65)/RNA complex substantially contracted by 15 Å in the maximum dimension, relative to the SF1/U2AF(65) complex in the absence of RNA ligand. In contrast, no detectable changes were observed for the isolated SF1 and U2AF(65) splicing factors or their individual complexes with RNA, although slight differences in the shapes of their molecular envelopes were apparent. We propose that the conformational changes that are induced by assembly of the SF1/U2AF(65)/RNA complex serve to position the pre-mRNA splice site optimally for subsequent stages of splicing.
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Affiliation(s)
- Ankit Gupta
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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117
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Bai Y, Srivastava SK, Chang JH, Manley JL, Tong L. Structural basis for dimerization and activity of human PAPD1, a noncanonical poly(A) polymerase. Mol Cell 2011; 41:311-20. [PMID: 21292163 PMCID: PMC3057501 DOI: 10.1016/j.molcel.2011.01.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 10/04/2010] [Accepted: 12/18/2010] [Indexed: 02/06/2023]
Abstract
Poly(A) polymerases (PAPs) are found in most living organisms and have important roles in RNA function and metabolism. Here, we report the crystal structure of human PAPD1, a noncanonical PAP that can polyadenylate RNAs in the mitochondria (also known as mtPAP) and oligouridylate histone mRNAs (TUTase1). The overall structure of the palm and fingers domains is similar to that in the canonical PAPs. The active site is located at the interface between the two domains, with a large pocket that can accommodate the substrates. The structure reveals the presence of a previously unrecognized domain in the N-terminal region of PAPD1, with a backbone fold that is similar to that of RNP-type RNA binding domains. This domain (named the RL domain), together with a β-arm insertion in the palm domain, contributes to dimerization of PAPD1. Surprisingly, our mutagenesis and biochemical studies show that dimerization is required for the catalytic activity of PAPD1.
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Affiliation(s)
- Yun Bai
- Department of Biological Sciences Columbia University New York, NY10027, USA
| | | | - Jeong Ho Chang
- Department of Biological Sciences Columbia University New York, NY10027, USA
| | - James L. Manley
- Department of Biological Sciences Columbia University New York, NY10027, USA
| | - Liang Tong
- Department of Biological Sciences Columbia University New York, NY10027, USA
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118
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McLaughlin KJ, Jenkins JL, Kielkopf CL. Large favorable enthalpy changes drive specific RNA recognition by RNA recognition motif proteins. Biochemistry 2011; 50:1429-31. [PMID: 21261285 DOI: 10.1021/bi102057m] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The RNA recognition motif (RRM) is a prevalent class of RNA binding domains. Although a number of RRM/RNA structures have been determined, thermodynamic analyses are relatively uncommon. Here, we use isothermal titration calorimetry to characterize single-stranded (ss)RNA binding by four representative RRM-containing proteins: (i) U2AF(65), (ii) SXL, (iii) TIA-1, and (iv) PAB. In all cases, ssRNA binding is accompanied by remarkably large favorable enthalpy changes (-30 to -60 kcal mol(-1)) and unfavorable entropy changes. Alterations of key RRM residues and binding sites indicate that under the nearly physiological conditions of these studies, large thermodynamic changes represent a signature of specific ssRNA recognition by RRMs.
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Affiliation(s)
- Krystle J McLaughlin
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States
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119
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Woolls HA, Lamanna AC, Karbstein K. Roles of Dim2 in ribosome assembly. J Biol Chem 2011; 286:2578-86. [PMID: 21075849 PMCID: PMC3024753 DOI: 10.1074/jbc.m110.191494] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/12/2010] [Indexed: 12/25/2022] Open
Abstract
In eukaryotes, ribosome assembly requires hundreds of conserved essential proteins not present in the mature particle. Despite their importance, the function of most factors remains unknown. This is because protein deletion often affects the composition of the entire particle. Additionally, many proteins are present in assembling ribosomes for extended times, which makes it difficult to pinpoint their role to a particular step. Here we have combined classical yeast biochemistry with experiments using recombinant proteins and RNA to study the role of Dim2 and its interaction with Nob1, the nuclease that generates the 3'-end of 18 S rRNA. Analysis of Dim2 mutants in which the interaction with Nob1 is disrupted demonstrates that this interaction between Dim2 and Nob1 is essential for optimal growth, and RNA binding experiments show that Dim2 increases Nob1 RNA affinity. Furthermore, our data indicate that Dim2 helps regulate Nob1 cleavage activity at the 3'-end of 18 S rRNA, as point mutants where this interaction is abolished in vitro accumulate pre-ribosomes containing Nob1 and 20 S rRNA in vivo. Interestingly, the site of interaction with Nob1 is mapped to the canonical RNA binding surface of a KH-like domain in Dim2, providing another example where an RNA-binding domain can be repurposed for protein interactions.
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Affiliation(s)
| | - Allison C. Lamanna
- the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Katrin Karbstein
- From the Program in Chemical Biology and
- the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
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120
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Tunnicliffe RB, Hautbergue GM, Kalra P, Jackson BR, Whitehouse A, Wilson SA, Golovanov AP. Structural basis for the recognition of cellular mRNA export factor REF by herpes viral proteins HSV-1 ICP27 and HVS ORF57. PLoS Pathog 2011; 7:e1001244. [PMID: 21253573 PMCID: PMC3017119 DOI: 10.1371/journal.ppat.1001244] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 11/26/2010] [Indexed: 01/21/2023] Open
Abstract
The herpesvirus proteins HSV-1 ICP27 and HVS ORF57 promote viral mRNA export by utilizing the cellular mRNA export machinery. This function is triggered by binding to proteins of the transcription-export (TREX) complex, in particular to REF/Aly which directs viral mRNA to the TAP/NFX1 pathway and, subsequently, to the nuclear pore for export to the cytoplasm. Here we have determined the structure of the REF-ICP27 interaction interface at atomic-resolution and provided a detailed comparison of the binding interfaces between ICP27, ORF57 and REF using solution-state NMR. Despite the absence of any obvious sequence similarity, both viral proteins bind on the same site of the folded RRM domain of REF, via short but specific recognition sites. The regions of ICP27 and ORF57 involved in binding by REF have been mapped as residues 104–112 and 103–120, respectively. We have identified the pattern of residues critical for REF/Aly recognition, common to both ICP27 and ORF57. The importance of the key amino acid residues within these binding sites was confirmed by site-directed mutagenesis. The functional significance of the ORF57-REF/Aly interaction was also probed using an ex vivo cytoplasmic viral mRNA accumulation assay and this revealed that mutants that reduce the protein-protein interaction dramatically decrease the ability of ORF57 to mediate the nuclear export of intronless viral mRNA. Together these data precisely map amino acid residues responsible for the direct interactions between viral adaptors and cellular REF/Aly and provide the first molecular details of how herpes viruses access the cellular mRNA export pathway. When invading host cells, herpes viruses highjack cellular components to allow them to replicate. It has been long recognized that each herpes virus has a specific signature adaptor protein which, among other functions, inserts viral mRNA into the cellular mRNA nuclear export pathway, enabling production of viral proteins by the host cell. This process has been extensively studied in vivo and in vitro, but despite many efforts, the molecular and structural mechanisms of key interactions between viral adaptors and cellular mRNA export factors have not been described. Here we present the first atomic-resolution structure of the key complex between the archetypal viral adaptor ICP27 (from Herpes simplex virus 1) and the cellular mRNA export factor REF, responsible for introducing viral mRNA into the cellular nuclear export pathway. We demonstrate that despite the absence of obvious sequence similarity, the adaptor protein ORF57 from a different herpes virus (Herpesvirus saimiri) binds REF in the same site and in a similar way. We have identified and studied amino acid residues responsible for REF recognition. Together the data provide the first molecular insight into how herpesviral signature proteins recognize cellular proteins, obtaining access to the cellular mRNA export machinery.
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Affiliation(s)
- Richard B. Tunnicliffe
- Faculty of Life Sciences and Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
| | - Guillaume M. Hautbergue
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Priti Kalra
- Faculty of Life Sciences and Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
| | - Brian R. Jackson
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Adrian Whitehouse
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Stuart A. Wilson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Alexander P. Golovanov
- Faculty of Life Sciences and Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
- * E-mail:
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121
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Qiu ZR, Schwer B, Shuman S. Determinants of Nam8-dependent splicing of meiotic pre-mRNAs. Nucleic Acids Res 2011; 39:3427-45. [PMID: 21208980 PMCID: PMC3082912 DOI: 10.1093/nar/gkq1328] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Nam8, a component of yeast U1 snRNP, is optional for mitotic growth but required during meiosis, because Nam8 collaborates with Mer1 to promote splicing of essential meiotic mRNAs AMA1, MER2 and MER3. Here, we identify SPO22 and PCH2 as novel targets of Nam8-dependent meiotic splicing. Whereas SPO22 splicing is co-dependent on Mer1, PCH2 is not. The SPO22 intron has a non-consensus 5′ splice site (5′SS) that dictates its Nam8/Mer1-dependence. SPO22 splicing relies on Mer1 recognition, via its KH domain, of an intronic enhancer 5′-AYACCCUY. Mutagenesis of KH and the enhancer highlights Arg214 and Gln243 and the CCC triplet as essential for Mer1 activity. The Nam8-dependent PCH2 pre-mRNA has a consensus 5′SS and lacks a Mer1 enhancer. For PCH2, a long 5′ exon and a non-consensus intron branchpoint dictate Nam8-dependence. Our results implicate Nam8 in two distinct meiotic splicing regulons. Nam8 is composed of three RRM domains, flanked by N-terminal leader and C-terminal tail segments. The leader, tail and RRM1 are dispensable for splicing meiotic targets and unnecessary for vegetative Nam8 function in multiple synthetic lethal genetic backgrounds. Nam8 activity is enfeebled by alanine mutations in the putative RNA binding sites of the RRM2 and RRM3 domains.
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Affiliation(s)
- Zhicheng R Qiu
- Sloan-Kettering Institute, Weill Cornell Medical College, New York, NY 10065, USA
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122
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Genomic mRNA profiling reveals compensatory mechanisms for the requirement of the essential splicing factor U2AF. Mol Cell Biol 2010; 31:652-61. [PMID: 21149581 DOI: 10.1128/mcb.01000-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The large subunit of the U2 auxiliary factor (U2AF) recognizes the polypyrimidine tract (Py-tract) located adjacent to the 3' splice site to facilitate U2 snRNP recruitment. While U2AF is considered essential for pre-mRNA splicing, its requirement for splicing on a genome-wide level has not been analyzed. Using Solexa sequencing, we performed mRNA profiling for splicing in the Schizosaccharomyces pombe U2AF(59) (prp2.1) temperature-sensitive mutant. Surprisingly, our analysis revealed that introns show a range of splicing defects in the mutant strain. While U2AF(59) inactivation (nonpermissive) conditions inhibit splicing of some introns, others are spliced apparently normally. Bioinformatics analysis indicated that U2AF(59)-insensitive introns have stronger 5' splice sites and higher A/U content. Most importantly, features that contribute to U2AF(59) insensitivity of an intron unexpectedly reside in its 5'-most 30 nucleotides. These include the 5' splice site, a guanosine at position 7, and the 5' splice site-to-branch point sequence context. A differential requirement (similar to U2AF(59)) for introns may also apply to other general splicing factors (e.g., prp10). Our combined results indicate that U2AF insensitivity is a common phenomenon and that varied intron features support the existence of unrecognized aspects of spliceosome assembly.
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123
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Cerdà-Costa N, Bonet J, Fernández MR, Avilés FX, Oliva B, Villegas S. Prediction of a new class of RNA recognition motif. J Mol Model 2010; 17:1863-75. [PMID: 21082207 DOI: 10.1007/s00894-010-0888-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 10/21/2010] [Indexed: 10/18/2022]
Abstract
The observation that activation domains (AD) of procarboxypeptidases are rather long compared to the pro-regions of other zymogens raises the possibility that they could play additional roles apart from precluding enzymatic activity within the proenzyme and helping in its folding process. In the present work, we compared the overall pro-domain tertiary structure with several proteins belonging to the same fold in the structural classification of proteins (SCOP) database by using structure and sequence comparisons. The best score obtained was between the activation domain of human procarboxypeptidase A4 (ADA4h) and the human U1A protein from the U1 snRNP. Structural alignment revealed the existence of RNP1- and RNP2-related sequences in ADA4h. After modeling ADA4h on U1A, the new structure was used to extract a new sequence pattern characteristic for important residues at key positions. The new sequence pattern allowed scanning protein sequences to predict the RNA-binding function for 32 sequences undetected by PFAM. Unspecific RNA electrophoretic mobility shift assays experimentally supported the prediction that ADA4h binds an RNA motif similar to the U1A binding-motif of stem-loop II of U1 small nuclear RNA. The experiments carried out with ADA4h in the present work suggest the sharing of a common ancestor with other RNA recognition motifs. However, the fact that key residues preventing activity within the proenzyme are also key residues for RNA binding might have induced the activation domains of procarboxypeptidases to evolve from the canonical RNP1 and RNP2 sequences.
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Affiliation(s)
- Núria Cerdà-Costa
- Departament de Bioquímica i Biologia Molecular, Unitat de Biociències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
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124
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Tsuda K, Someya T, Kuwasako K, Takahashi M, He F, Unzai S, Inoue M, Harada T, Watanabe S, Terada T, Kobayashi N, Shirouzu M, Kigawa T, Tanaka A, Sugano S, Güntert P, Yokoyama S, Muto Y. Structural basis for the dual RNA-recognition modes of human Tra2-β RRM. Nucleic Acids Res 2010; 39:1538-53. [PMID: 20926394 PMCID: PMC3045587 DOI: 10.1093/nar/gkq854] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human Transformer2-β (hTra2-β) is an important member of the serine/arginine-rich protein family, and contains one RNA recognition motif (RRM). It controls the alternative splicing of several pre-mRNAs, including those of the calcitonin/calcitonin gene-related peptide (CGRP), the survival motor neuron 1 (SMN1) protein and the tau protein. Accordingly, the RRM of hTra2-β specifically binds to two types of RNA sequences [the CAA and (GAA)(2) sequences]. We determined the solution structure of the hTra2-β RRM (spanning residues Asn110-Thr201), which not only has a canonical RRM fold, but also an unusual alignment of the aromatic amino acids on the β-sheet surface. We then solved the complex structure of the hTra2-β RRM with the (GAA)(2) sequence, and found that the AGAA tetra-nucleotide was specifically recognized through hydrogen-bond formation with several amino acids on the N- and C-terminal extensions, as well as stacking interactions mediated by the unusually aligned aromatic rings on the β-sheet surface. Further NMR experiments revealed that the hTra2-β RRM recognizes the CAA sequence when it is integrated in the stem-loop structure. This study indicates that the hTra2-β RRM recognizes two types of RNA sequences in different RNA binding modes.
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Affiliation(s)
- Kengo Tsuda
- RIKEN Systems and Structural Biology Center, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
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125
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Kondé E, Bourgeois B, Tellier-Lebegue C, Wu W, Pérez J, Caputo S, Attanda W, Gasparini S, Charbonnier JB, Gilquin B, Worman HJ, Zinn-Justin S. Structural analysis of the Smad2-MAN1 interaction that regulates transforming growth factor-β signaling at the inner nuclear membrane. Biochemistry 2010; 49:8020-32. [PMID: 20715792 DOI: 10.1021/bi101153w] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
MAN1, an integral protein of the inner nuclear membrane, influences transforming growth factor-β (TGF-β) signaling by directly interacting with R-Smads. Heterozygous loss of function mutations in the gene encoding MAN1 cause sclerosing bone dysplasias and an increased level of TGF-β signaling in cells. As a first step in elucidating the mechanism of TGF-β pathway regulation by MAN1, we characterized the structure of the MAN1 C-terminal region that binds Smad2. Using nuclear magnetic resonance spectroscopy, we observed that this region is comprised of a winged helix domain, a structurally heterogeneous linker, a U2AF homology motif (UHM) domain, and a disordered C-terminus. From nuclear magnetic resonance and small-angle X-ray scattering data, we calculated a family of models for this MAN1 region. Our data indicate that the linker plays the role of an intramolecular UHM ligand motif (ULM) interacting with the UHM domain. We mapped the Smad2 binding site onto the MAN1 structure by combining GST pull-down, fluorescence, and yeast two-hybrid approaches. The linker region, the UHM domain, and the C-terminus are necessary for Smad2 binding with a micromolar affinity. Moreover, the intramolecular interaction between the linker and the UHM domain is critical for Smad2 binding. On the basis of the structural heterogeneity and binding properties of the linker, we suggest that it can interact with other UHM domains, thus regulating the MAN1-Smad2 interaction.
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Affiliation(s)
- Emilie Kondé
- Laboratoire de Biologie Structurale et Radiobiologie, URA CNRS 2096, CEA Saclay, 91190 Gif-sur-Yvette, France
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126
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Hubé F, Velasco G, Rollin J, Furling D, Francastel C. Steroid receptor RNA activator protein binds to and counteracts SRA RNA-mediated activation of MyoD and muscle differentiation. Nucleic Acids Res 2010; 39:513-25. [PMID: 20855289 PMCID: PMC3025577 DOI: 10.1093/nar/gkq833] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The steroid receptor RNA activator (SRA) has the unusual property to function as both a non-coding RNA (ncRNA) and a protein SRAP. SRA ncRNA is known to increase the activity of a range of nuclear receptors as well as the master regulator of muscle differentiation MyoD. The contribution of SRA to either a ncRNA or a protein is influenced by alternative splicing of the first intron, the retention of which disrupts the SRAP open reading frame. We reported here that the ratio between non-coding and coding SRA isoforms increased during myogenic differentiation of human satellite cells but not myotonic dystrophy patient satellite cells, in which differentiation capacity is affected. Using constructs that exclusively produce SRA ncRNA or SRAP, we demonstrated that whereas SRA ncRNA was indeed an enhancer of myogenic differentiation and myogenic conversion of non-muscle cells through the co-activation of MyoD activity, SRAP prevented this SRA RNA-dependant co-activation. Interestingly, the SRAP inhibitory effect is mediated through the interaction of SRAP with its RNA counterpart via its RRM-like domain interacting with the functional sub-structure of SRA RNA, STR7. This study thus provides a new model for SRA-mediated regulation of MyoD transcriptional activity in the promotion of normal muscle differentiation, which takes into account the nature of SRA molecules present.
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Affiliation(s)
- Florent Hubé
- Université Paris Diderot-Paris7, CNRS UMR7216, Epigenetics and Cell Fate, Paris, France.
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127
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Hsiao HH, Nath A, Lin CY, Folta-Stogniew EJ, Rhoades E, Braddock DT. Quantitative characterization of the interactions among c-myc transcriptional regulators FUSE, FBP, and FIR. Biochemistry 2010; 49:4620-34. [PMID: 20420426 DOI: 10.1021/bi9021445] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human c-myc is critical for cell homeostasis and growth but is a potent oncogenic factor if improperly regulated. The c-myc far-upstream element (FUSE) melts into single-stranded DNA upon active transcription, and the noncoding strand FUSE recruits an activator [the FUSE-binding protein (FBP)] and a repressor [the FBP-interacting repressor (FIR)] to fine-tune c-myc transcription in a real-time manner. Despite detailed biological experiments describing this unique mode of transcriptional regulation, quantitative measurements of the physical constants regulating the protein-DNA interactions remain lacking. Here, we first demonstrate that the two FUSE strands adopt different conformations upon melting, with the noncoding strand DNA in an extended, linear form. FBP binds to the linear noncoding FUSE with a dissociation constant in the nanomolar range. FIR binds to FUSE more weakly, having its modest dissociation constants in the low micromolar range. FIR is monomeric under near-physiological conditions but upon binding of FUSE dimerizes into a 2:1 FIR(2)-FUSE complex mediated by the RRMs. In the tripartite interaction, our analysis suggests a stepwise addition of FIR onto an activating FBP-FUSE complex to form a quaternary FIR(2)-FBP-FUSE inhibitory complex. Our quantitative characterization enhances understanding of DNA strand preference and the mechanism of the stepwise complex formation in the FUSE-FBP-FIR regulatory system.
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Affiliation(s)
- Hsin-Hao Hsiao
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
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128
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Chang J, Schwer B, Shuman S. Mutational analyses of trimethylguanosine synthase (Tgs1) and Mud2: proteins implicated in pre-mRNA splicing. RNA (NEW YORK, N.Y.) 2010; 16:1018-31. [PMID: 20360394 PMCID: PMC2856874 DOI: 10.1261/rna.2082610] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Yeast and human Tgs1 are orthologous RNA cap (guanine-N2) methyltransferases that convert m(7)G caps into the 2,2,7-trimethylguanosine (TMG) caps characteristic of spliceosomal snRNAs. TMG caps are dispensable for vegetative yeast growth, but are essential in the absence of Mud2, the putative yeast homolog of human splicing factor U2AF. Here we exploited the synthetic lethal interactions of tgs1Delta and mud2Delta mutations to identify essential structural features of the Tgs1 and Mud2 proteins. Thirty-two new mutations were introduced into human Tgs1 and surveyed for their effects on function in vivo in yeast and on the two sequential guanine-N2 methylation reactions in vitro. The structure-function data highlight a strictly essential pi-cation interaction between Trp766 and the m(7)G base and a network of important enzymic contacts to the cap triphosphate via Lys646, Tyr771, Arg807, and Lys836. Mud2 is a 527-amino acid polypeptide composed of a hydrophilic N-terminal domain and a C-terminal RRM domain. We found that the RRM domain is necessary but not sufficient for Mud2 function in complementing growth of tgs1Delta mud2Delta and mud1Delta mud2Delta strains. Other changes in Mud2 elicited distinct phenotypes in tgs1Delta versus mud1Delta backgrounds. mud2Delta also caused a severe growth defect in cells lacking the Tgs1-binding protein encoded by the nonessential gene YNR004w (now renamed SWM2, synthetic with mud2Delta). Mud2 mutational effects in the swm2Delta background paralleled those for mud1Delta. The requirements for Mud2 function are apparently more stringent when yeast cells lack TMG caps than when they lack Mud1 or Swm2.
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Affiliation(s)
- Jonathan Chang
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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129
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Elantak L, Wagner S, Herrmannová A, Karásková M, Rutkai E, Lukavsky PJ, Valásek L. The indispensable N-terminal half of eIF3j/HCR1 cooperates with its structurally conserved binding partner eIF3b/PRT1-RRM and with eIF1A in stringent AUG selection. J Mol Biol 2010; 396:1097-116. [PMID: 20060839 PMCID: PMC2824034 DOI: 10.1016/j.jmb.2009.12.047] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 12/17/2009] [Accepted: 12/22/2009] [Indexed: 11/13/2022]
Abstract
Despite the recent progress in our understanding of the numerous
functions of individual subunits of eukaryotic translation initiation factor 3
(eIF3), there is still only little known on the molecular level. Using NMR
spectroscopy, we determined the first solution structure of an interaction
between eIF3 subunits. We revealed that a conserved tryptophan residue in the
human eIF3j N-terminal acidic domain (NTA) is held in the helix α1
– loop L5 hydrophobic pocket of the human eIF3b-RRM. Mutating the
corresponding “pocket” residues in its yeast orthologue reduces
cellular growth rate, eliminates eIF3j/HCR1 association with eIF3b/PRT1
in vitro and in vivo, affects
40S-occupancy of eIF3, and produces a leaky scanning defect indicative of a
deregulation of the AUG selection process. Unexpectedly, we found that the
N-terminal half (NTD) of eIF3j/HCR1 containing the NTA motif is indispensable
and sufficient for wild-type growth of yeast cells. Furthermore, we demonstrate
that deletion of either j/HCR1 or its NTD only, or mutating the key tryptophan
residues results in the severe leaky scanning phenotype partially suppressible
by overexpressed eIF1A, which is thought to stabilize properly formed
pre-initiation complexes at the correct start codon. These findings indicate
that eIF3j/HCR1 remains associated with the scanning pre-initiation complexes
and does not dissociate from the small ribosomal subunit upon mRNA recruitment
as previously believed. Finally, we provide further support for earlier mapping
of the ribosomal binding site for human eIF3j by identifying specific
interactions of eIF3j/HCR1 with small ribosomal proteins RPS2 and RPS23 located
in the vicinity of the mRNA entry channel. Taken together we propose that
eIF3j/HCR1 closely co-operates with eIF3b/PRT1-RRM and eIF1A on the ribosome to
ensure proper formation of the scanning-arrested conformation required for
stringent AUG recognition.
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Affiliation(s)
- Latifa Elantak
- Structural Studies Division, MRC-Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, England, UK
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130
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131
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de Chiara C, Menon RP, Strom M, Gibson TJ, Pastore A. Phosphorylation of S776 and 14-3-3 binding modulate ataxin-1 interaction with splicing factors. PLoS One 2009; 4:e8372. [PMID: 20037628 PMCID: PMC2791216 DOI: 10.1371/journal.pone.0008372] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 11/16/2009] [Indexed: 12/02/2022] Open
Abstract
Ataxin-1 (Atx1), a member of the polyglutamine (polyQ) expanded protein family, is responsible for spinocerebellar ataxia type 1. Requirements for developing the disease are polyQ expansion, nuclear localization and phosphorylation of S776. Using a combination of bioinformatics, cell and structural biology approaches, we have identified a UHM ligand motif (ULM), present in proteins associated with splicing, in the C-terminus of Atx1 and shown that Atx1 interacts with and influences the function of the splicing factor U2AF65 via this motif. ULM comprises S776 of Atx1 and overlaps with a nuclear localization signal and a 14-3-3 binding motif. We demonstrate that phosphorylation of S776 provides the molecular switch which discriminates between 14-3-3 and components of the spliceosome. We also show that an S776D Atx1 mutant previously designed to mimic phosphorylation is unsuitable for this aim because of the different chemical properties of the two groups. Our results indicate that Atx1 is part of a complex network of interactions with splicing factors and suggest that development of the pathology is the consequence of a competition of aggregation with native interactions. Studies of the interactions formed by non-expanded Atx1 thus provide valuable hints for understanding both the function of the non-pathologic protein and the causes of the disease.
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Affiliation(s)
- Cesira de Chiara
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Rajesh P. Menon
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Molly Strom
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Toby J. Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Annalisa Pastore
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
- * E-mail:
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132
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Lee JH, Rangarajan ES, Yogesha SD, Izard T. Raver1 interactions with vinculin and RNA suggest a feed-forward pathway in directing mRNA to focal adhesions. Structure 2009; 17:833-42. [PMID: 19523901 DOI: 10.1016/j.str.2009.04.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 04/09/2009] [Accepted: 04/10/2009] [Indexed: 10/20/2022]
Abstract
The translational machinery of the cell relocalizes to focal adhesions following the activation of integrin receptors. This response allows for rapid, local production of components needed for adhesion complex assembly and signaling. Vinculin links focal adhesions to the actin cytoskeleton following its activation by integrin signaling, which severs intramolecular interactions of vinculin's head and tail (Vt) domains. Our vinculin:raver1 crystal structures and binding studies show that activated Vt selectively interacts with one of the three RNA recognition motifs of raver1, that the vinculin:raver1 complex binds to F-actin, and that raver1 binds selectively to RNA, including a sequence found in vinculin mRNA. Further, mutation of residues that mediate interaction of raver1 with vinculin abolish their colocalization in cells. These findings suggest a feed-forward model where vinculin activation at focal adhesions provides a scaffold for recruitment of raver1 and its mRNA cargo to facilitate the production of components of adhesion complexes.
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Affiliation(s)
- Jun Hyuck Lee
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
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133
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Abstract
The localization of mRNAs in subcellular compartments is an efficient way to spatially restrict gene expression. Crystal structures of raver1-vinculin reported by Izard and coworkers now suggest a possible mechanism for mRNA localization during the assembly of focal adhesions.
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134
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Ritchie DB, Schellenberg MJ, MacMillan AM. Spliceosome structure: piece by piece. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:624-33. [PMID: 19733268 DOI: 10.1016/j.bbagrm.2009.08.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/22/2009] [Accepted: 08/27/2009] [Indexed: 10/20/2022]
Abstract
Processing of pre-mRNAs by RNA splicing is an essential step in the maturation of protein coding RNAs in eukaryotes. Structural studies of the cellular splicing machinery, the spliceosome, are a major challenge in structural biology due to the size and complexity of the splicing ensemble. Specifically, the structural details of splice site recognition and the architecture of the spliceosome active site are poorly understood. X-ray and NMR techniques have been successfully used to address these questions defining the structure of individual domains, isolated splicing proteins, spliceosomal RNA fragments and recently the U1 snRNP multiprotein.RNA complex. These results combined with extant biochemical and genetic data have yielded important insights as well as posing fresh questions with respect to the regulation and mechanism of this critical gene regulatory process.
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Affiliation(s)
- Dustin B Ritchie
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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135
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The shuttling protein Npl3 promotes translation termination accuracy in Saccharomyces cerevisiae. J Mol Biol 2009; 394:410-22. [PMID: 19733178 DOI: 10.1016/j.jmb.2009.08.067] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/24/2009] [Accepted: 08/29/2009] [Indexed: 01/20/2023]
Abstract
Heterogeneous nuclear ribonucleoproteins are multifunctional proteins that bind to newly synthesized mRNAs in the nucleus and participate in many subsequent steps of gene expression. A well-studied Saccharomyces cerevisiae heterogeneous nuclear ribonucleoprotein that has several nuclear functions is Npl3p. Here, we provide evidence that Npl3p also has a cytoplasmic role: it functions in translation termination fidelity. Yeast harboring the npl3-95 mutant allele have an impaired ability to translate lacZ, enhanced sensitivity to cycloheximide and paromomycin, and increased ability to read through translation termination codons. Most of these defects are enhanced in yeast that also lack Upf1p, an RNA surveillance factor crucial for translation termination. We show that the npl3-95 mutant allele encodes a form of Npl3p that is part of high molecular-weight complexes that cofractionate with the poly(A)-binding protein Pab1p. Together, these results lead us to propose a model in which Npl3p engenders translational fidelity by promoting the remodeling of mRNPs during translation termination.
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136
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Mrd1p is required for release of base-paired U3 snoRNA within the preribosomal complex. Mol Cell Biol 2009; 29:5763-74. [PMID: 19704003 DOI: 10.1128/mcb.00428-09] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In eukaryotes, ribosomes are made from precursor rRNA (pre-rRNA) and ribosomal proteins in a maturation process that requires a large number of snoRNPs and processing factors. A fundamental problem is how the coordinated and productive folding of the pre-rRNA and assembly of successive pre-rRNA-protein complexes is achieved cotranscriptionally. The conserved protein Mrd1p, which contains five RNA binding domains (RBDs), is essential for processing events leading to small ribosomal subunit synthesis. We show that full function of Mrd1p requires all five RBDs and that the RBDs are functionally distinct and needed during different steps in processing. Mrd1p mutations trap U3 snoRNA in pre-rRNP complexes both in base-paired and non-base-paired interactions. A single essential RBD, RBD5, is involved in both types of interactions, but its conserved RNP1 motif is not needed for releasing the base-paired interactions. RBD5 is also required for the late pre-rRNP compaction preceding A(2) cleavage. Our results suggest that Mrd1p modulates successive conformational rearrangements within the pre-rRNP that influence snoRNA-pre-rRNA contacts and couple U3 snoRNA-pre-rRNA remodeling and late steps in pre-rRNP compaction that are essential for cleavage at A(0) to A(2). Mrd1p therefore coordinates key events in biosynthesis of small ribosome subunits.
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137
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Prigge JR, Iverson SV, Siders AM, Schmidt EE. Interactome for auxiliary splicing factor U2AF(65) suggests diverse roles. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:487-92. [PMID: 19540372 DOI: 10.1016/j.bbagrm.2009.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 06/10/2009] [Accepted: 06/15/2009] [Indexed: 12/17/2022]
Abstract
U2 small nuclear ribonucleoprotein auxiliary factor (U2AF) is an essential component of the splicing machinery that is composed of two protein subunits, the 35 kDa U2AF(35) (U2AF1) and the 65 kDa U2AF(65) (U2AF2). U2AF interacts with various splicing factors within this machinery. Here we expand the list of mammalian splicing factors that are known to interact with U2AF(65) as well as the list of nuclear proteins not known to participate in splicing that interact with U2AF(65). Using a yeast two-hybrid system, we found fourteen U2AF(65)-interacting proteins. The validity of the screen was confirmed by identification of five known U2AF(65)-interacting proteins, including its heterodimeric partner, U2AF(35). In addition to binding these known partners, we found previously unrecognized U2AF(65) interactions with four splicing-related proteins (DDX39, SFRS3, SFRS18, SNRPA), two zinc finger proteins (ZFP809 and ZC3H11A), a U2AF(65) homolog (RBM39), and two other regulatory proteins (DAXX and SERBP1). We report which regions of U2AF(65) each of these proteins interacts with and we discuss their potential roles in regulation of pre-mRNA splicing, 3'-end mRNA processing, and U2AF(65) sub-nuclear localization. These findings suggest expanded roles for U2AF(65) in both splicing and non-splicing functions.
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Affiliation(s)
- Justin R Prigge
- Department of Veterinary Molecular Biology, Montana State University, Molecular Biosciences, 960 Technology Blvd., Bozeman, MT 59718, USA
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138
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McGrail JC, Krause A, O'Keefe RT. The RNA binding protein Cwc2 interacts directly with the U6 snRNA to link the nineteen complex to the spliceosome during pre-mRNA splicing. Nucleic Acids Res 2009; 37:4205-17. [PMID: 19435883 PMCID: PMC2715229 DOI: 10.1093/nar/gkp341] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Intron removal during pre-messenger RNA (pre-mRNA) splicing involves arrangement of snRNAs into conformations that promote the two catalytic steps. The Prp19 complex [nineteen complex (NTC)] can specify U5 and U6 snRNA interactions with pre-mRNA during spliceosome activation. A candidate for linking the NTC to the snRNAs is the NTC protein Cwc2, which contains motifs known to bind RNA, a zinc finger and RNA recognition motif (RRM). In yeast cells mutation of either the zinc finger or RRM destabilize Cwc2 and are lethal. Yeast cells depleted of Cwc2 accumulate pre-mRNA and display reduced levels of U1, U4, U5 and U6 snRNAs. Cwc2 depletion also reduces U4/U6 snRNA complex levels, as found with depletion of other NTC proteins, but without increase in free U4. Purified Cwc2 displays general RNA binding properties and can bind both snRNAs and pre-mRNA in vitro. A Cwc2 RRM fragment alone can bind RNA but with reduced efficiency. Under splicing conditions Cwc2 can associate with U2, U5 and U6 snRNAs, but can only be crosslinked directly to the U6 snRNA. Cwc2 associates with U6 both before and after the first step of splicing. We propose that Cwc2 links the NTC to the spliceosome during pre-mRNA splicing through the U6 snRNA.
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Affiliation(s)
- Joanne C McGrail
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT
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139
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Vazquez MP, Mualem D, Bercovich N, Stern MZ, Nyambega B, Barda O, Nasiga D, Gupta SK, Michaeli S, Levin MJ. Functional characterization and protein-protein interactions of trypanosome splicing factors U2AF35, U2AF65 and SF1. Mol Biochem Parasitol 2009; 164:137-46. [PMID: 19320097 DOI: 10.1016/j.molbiopara.2008.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Early in the assembly of eukaryotes the branch-point binding protein (BBP, also called SF1) recognizes the branch point sequence, whereas the heterodimer U2AF, consisting of a 65 and a 35 kDa subunit, contacts the polypyrimidine tract and the AG splice site, respectively. Herein, we identified, cloned and expressed the Trypanosoma cruzi and Trypanosoma brucei U2AF35, U2AF65 and SF1. Trypanosomatid U2AF65 strongly diverged from yeast and human homologues. On the contrary, trypanosomatid SF1 was conserved but lacked the C-terminal sequence present in the mammalian protein. Yeast two hybrid approaches were used to assess their interactions. The interaction between U2AF35 and U2AF65 was very weak or not detectable. However, as in other eukaryotes, the interaction between U2AF65 and SF1 was strong. At the cellular level, these results were confirmed by fractionation and affinity-selection experiments in which SF1 and U2AF65 were affinity-selected with TAP tagged SF1, but not with TAP tagged U2AF35. Silencing one of the three factors affected growth and trans-splicing in the first step of this reaction. Trypanosomes are the first described example of eukaryotic cells in which the interaction of two expressed U2AF factors seemed to be very weak, or not detectable.
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Affiliation(s)
- Martin P Vazquez
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
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140
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Identification of core components of the exon junction complex in trypanosomes. Mol Biochem Parasitol 2009; 166:190-3. [PMID: 19450736 DOI: 10.1016/j.molbiopara.2009.03.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 03/20/2009] [Accepted: 03/24/2009] [Indexed: 11/22/2022]
Abstract
In animal cells, the exon junction complex (EJC) is deposited onto mRNAs during the second step of splicing, 20-24 nt upstream of the exon-exon junction. The EJC core contains four proteins: Mago, Y14, eIF4AIII and Btz. In trypanosomes, cis-splicing is very rare but all mRNAs are subject to 5'trans-splicing of a 39-nt RNA sequence. Here we show that trypanosomes have a conserved Mago and a divergent Y14 protein, but we were unable to identify a Btz orthologue. We demonstrate that Mago and Y14 form a stable heterodimer using yeast two hybrid analyses. We also show that this complex co-purifies in vivo in trypanosomes with a protein containing an NTF2 domain, typically involved in mRNA transport.
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141
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Petersen NHT, Joensen J, McKinney LV, Brodersen P, Petersen M, Hofius D, Mundy J. Identification of proteins interacting with Arabidopsis ACD11. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:661-6. [PMID: 18845362 DOI: 10.1016/j.jplph.2008.08.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 08/10/2008] [Indexed: 05/08/2023]
Abstract
The Arabidopsis ACD11 gene encodes a sphingosine transfer protein and was identified by the accelerated cell death phenotype of the loss of function acd11 mutant, which exhibits heightened expression of genes involved in the disease resistance hypersensitive response (HR). We used ACD11 as bait in a yeast two-hybrid screen of an Arabidopsis cDNA library to identify ACD11 interacting proteins. One interactor identified is a protein of unknown function with an RNA recognition motif (RRM) designated BPA1 (binding partner of ACD11). Co-immunoprecipitation experiments confirmed the ACD11-BPA1 interactions in vivo and in vitro. Two other ACD11 interactors (PRA7 and PRA8) are homologous to each other and to mammalian PRA1, and both were subsequently shown to interact with BPA1 in yeast. A fourth interactor (VAP27-1) is homologous to mammalian VAP-A, and was found to interact more strongly with a homolog of ACD11 than ACD11 itself. All interactors were shown to be associated with membrane fractions, suggesting that ACD11 function could be related to the regulation of membrane compartments.
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142
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Cambray S, Pedraza N, Rafel M, Garí E, Aldea M, Gallego C. Protein kinase KIS localizes to RNA granules and enhances local translation. Mol Cell Biol 2009; 29:726-35. [PMID: 19015237 PMCID: PMC2630681 DOI: 10.1128/mcb.01180-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2008] [Revised: 08/22/2008] [Accepted: 11/10/2008] [Indexed: 01/11/2023] Open
Abstract
The regulation of mRNA transport is a fundamental process for cytoplasmic sorting of transcripts and spatially controlled translational derepression once properly localized. There is growing evidence that translation is locally modulated as a result of specific synaptic inputs. However, the underlying molecular mechanisms that regulate this translational process are just emerging. We show that KIS, a serine/threonine kinase functionally related to microtubule dynamics and axon development, interacts with three proteins found in RNA granules: KIF3A, NonO, and eEF1A. KIS localizes to RNA granules and colocalizes with the KIF3A kinesin and the beta-actin mRNA in cultured cortical neurons. In addition, KIS is found associated with KIF3A and 10 RNP-transported mRNAs in brain extracts. The results of knockdown experiments indicate that KIS is required for normal neurite outgrowth. More important, the kinase activity of KIS stimulates 3' untranslated region-dependent local translation in neuritic projections. We propose that KIS is a component of the molecular device that modulates translation in RNA-transporting granules as a result of local signals.
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Affiliation(s)
- Serafí Cambray
- Departament de Ciències Mèdiques Bàsiques, IRBLLEIDA, Universitat de Lleida, Lleida, Catalonia, Spain
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143
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Bian Y, Masuda A, Matsuura T, Ito M, Okushin K, Engel AG, Ohno K. Tannic acid facilitates expression of the polypyrimidine tract binding protein and alleviates deleterious inclusion of CHRNA1 exon P3A due to an hnRNP H-disrupting mutation in congenital myasthenic syndrome. Hum Mol Genet 2009; 18:1229-37. [PMID: 19147685 PMCID: PMC2655771 DOI: 10.1093/hmg/ddp023] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We recently reported that the intronic splice-site mutation IVS3-8G>A of CHRNA1 that encodes the muscle nicotinic acetylcholine receptor alpha subunit disrupts binding of a splicing repressor, hnRNP H. This, in turn, results in exclusive inclusion of the downstream exon P3A. The P3A(+) transcript encodes a non-functional alpha subunit that comprises 50% of the transcripts in normal human skeletal muscle, but its functional significance remains undetermined. In an effort to search for a potential therapy, we screened off-label effects of 960 bioactive chemical compounds and found that tannic acid ameliorates the aberrant splicing due to IVS3-8G>A but without altering the expression of hnRNP H. Therefore, we searched for another splicing trans-factor. We found that the polypyrimidine tract binding protein (PTB) binds close to the 3' end of CHRNA1 intron 3, that PTB induces skipping of exon P3A and that tannic acid increases the expression of PTB in a dose-dependent manner. Deletion assays of the PTB promoter region revealed that the tannic acid-responsive element is between positions -232 and -74 from the translation initiation site. These observations open the door to the discovery of novel therapies based on PTB overexpression and to detecting possible untoward effects of the overexpression.
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Affiliation(s)
- Yang Bian
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
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144
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Roles of polypyrimidine tract binding proteins in major immediate-early gene expression and viral replication of human cytomegalovirus. J Virol 2009; 83:2839-50. [PMID: 19144709 DOI: 10.1128/jvi.02407-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Human cytomegalovirus (HCMV), a member of the beta subgroup of the family Herpesviridae, causes serious health problems worldwide. HCMV gene expression in host cells is a well-defined sequential process: immediate-early (IE) gene expression, early-gene expression, DNA replication, and late-gene expression. The most abundant IE gene, major IE (MIE) gene pre-mRNA, needs to be spliced before being exported to the cytoplasm for translation. In this study, the regulation of MIE gene splicing was investigated; in so doing, we found that polypyrimidine tract binding proteins (PTBs) strongly repressed MIE gene production in cotransfection assays. In addition, we discovered that the repressive effects of PTB could be rescued by splicing factor U2AF. Taken together, the results suggest that PTBs inhibit MIE gene splicing by competing with U2AF65 for binding to the polypyrimidine tract in pre-mRNA. In intron deletion mutation assays and RNA detection experiments (reverse transcription [RT]-PCR and real-time RT-PCR), we further observed that PTBs target all the introns of the MIE gene, especially intron 2, and affect gene splicing, which was reflected in the variation in the ratio of pre-mRNA to mRNA. Using transfection assays, we demonstrated that PTB knockdown cells induce a higher degree of MIE gene splicing/expression. Consistently, HCMV can produce more viral proteins and viral particles in PTB knockdown cells after infection. We conclude that PTB inhibits HCMV replication by interfering with MIE gene splicing through competition with U2AF for binding to the polypyrimidine tract in MIE gene introns.
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145
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Rao KN, Burley SK, Swaminathan S. UPF201 archaeal specific family members reveal structural similarity to RNA-binding proteins but low likelihood for RNA-binding function. PLoS One 2008; 3:e3903. [PMID: 19079550 PMCID: PMC2596488 DOI: 10.1371/journal.pone.0003903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 11/16/2008] [Indexed: 11/18/2022] Open
Abstract
We have determined X-ray crystal structures of four members of an archaeal specific family of proteins of unknown function (UPF0201; Pfam classification: DUF54) to advance our understanding of the genetic repertoire of archaea. Despite low pairwise amino acid sequence identities (10-40%) and the absence of conserved sequence motifs, the three-dimensional structures of these proteins are remarkably similar to one another. Their common polypeptide chain fold, encompassing a five-stranded antiparallel beta-sheet and five alpha-helices, proved to be quite unexpectedly similar to that of the RRM-type RNA-binding domain of the ribosomal L5 protein, which is responsible for binding the 5S- rRNA. Structure-based sequence alignments enabled construction of a phylogenetic tree relating UPF0201 family members to L5 ribosomal proteins and other structurally similar RNA binding proteins, thereby expanding our understanding of the evolutionary purview of the RRM superfamily. Analyses of the surfaces of these newly determined UPF0201 structures suggest that they probably do not function as RNA binding proteins, and that this domain specific family of proteins has acquired a novel function in archaebacteria, which awaits experimental elucidation.
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Affiliation(s)
- Krishnamurthy N. Rao
- Biology Department, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Stephen K. Burley
- Eli Lilly and Company, San Diego, California, United States of America
| | - Subramanyam Swaminathan
- Biology Department, Brookhaven National Laboratory, Upton, New York, United States of America
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146
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Brooks MA, Dziembowski A, Quevillon-Cheruel S, Henriot V, Faux C, van Tilbeurgh H, Séraphin B. Structure of the yeast Pml1 splicing factor and its integration into the RES complex. Nucleic Acids Res 2008; 37:129-43. [PMID: 19033360 PMCID: PMC2615620 DOI: 10.1093/nar/gkn894] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The RES complex was previously identified in yeast as a splicing factor affecting nuclear pre-mRNA retention. This complex was shown to contain three subunits, namely Snu17, Bud13 and Pml1, but its mode of action remains ill-defined. To obtain insights into its function, we have performed a structural investigation of this factor. Production of a short N-terminal truncation of residues that are apparently disordered allowed us to determine the X-ray crystallographic structure of Pml1. This demonstrated that it consists mainly of a FHA domain, a fold which has been shown to mediate interactions with phosphothreonine-containing peptides. Using a new sensitive assay based on alternative splice-site choice, we show, however, that mutation of the putative phosphothreonine-binding pocket of Pml1 does not affect pre-mRNA splicing. We have also investigated how Pml1 integrates into the RES complex. Production of recombinant complexes, combined with serial truncation and mutagenesis of their subunits, indicated that Pml1 binds to Snu17, which itself contacts Bud13. This analysis allowed us to demarcate the binding sites involved in the formation of this assembly. We propose a model of the organization of the RES complex based on these results, and discuss the functional consequences of this architecture.
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Affiliation(s)
- Mark A. Brooks
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
| | - Andrzej Dziembowski
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
| | - Sophie Quevillon-Cheruel
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
| | - Véronique Henriot
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
| | - Céline Faux
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
| | - Herman van Tilbeurgh
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
| | - Bertrand Séraphin
- IBBMC-CNRS UMR8619, IFR 115, Bât. 430, Université Paris-Sud, 91405 Orsay, Equipe Labelisée La Ligue, CGM, CNRS UPR2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Univ Paris-Sud, Orsay, F-91405 and Université Pierre et Marie Curie- Paris 6, Paris, F-75005, France
- *To whom correspondence should be addressed. Tel: + 33 1 69 82 38 84; Fax: + 33 1 69 82 38 77;
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147
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Corsini L, Hothorn M, Stier G, Rybin V, Scheffzek K, Gibson TJ, Sattler M. Dimerization and protein binding specificity of the U2AF homology motif of the splicing factor Puf60. J Biol Chem 2008; 284:630-639. [PMID: 18974054 DOI: 10.1074/jbc.m805395200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PUF60 is an essential splicing factor functionally related and homologous to U2AF(65). Its C-terminal domain belongs to the family of U2AF (U2 auxiliary factor) homology motifs (UHM), a subgroup of RNA recognition motifs that bind to tryptophan-containing linear peptide motifs (UHM ligand motifs, ULMs) in several nuclear proteins. Here, we show that the Puf60 UHM is mainly monomeric in physiological buffer, whereas its dimerization is induced upon the addition of SDS. The crystal structure of PUF60-UHM at 2.2 angstroms resolution, NMR data, and mutational analysis reveal that the dimer interface is mediated by electrostatic interactions involving a flexible loop. Using glutathione S-transferase pulldown experiments, isothermal titration calorimetry, and NMR titrations, we find that Puf60-UHM binds to ULM sequences in the splicing factors SF1, U2AF65, and SF3b155. Compared with U2AF65-UHM, Puf60-UHM has distinct binding preferences to ULMs in the N terminus of SF3b155. Our data suggest that the functional cooperativity between U2AF65 and Puf60 may involve simultaneous interactions of the two proteins with SF3b155.
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Affiliation(s)
- Lorenzo Corsini
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Michael Hothorn
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Gunter Stier
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Vladimir Rybin
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Klaus Scheffzek
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Michael Sattler
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, the Institute of Structural Biology, Helmholtz Zentrum Mu¨nchen, Ingolsta¨dter Landstrasse 1, 85764 Neuherberg, Germany, and the Munich Center for Integrated Protein Science and Chair Biomolecular NMR, Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747 Garching, Germany.
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148
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Trowitzsch S, Weber G, Lührmann R, Wahl MC. An unusual RNA recognition motif acts as a scaffold for multiple proteins in the pre-mRNA retention and splicing complex. J Biol Chem 2008; 283:32317-27. [PMID: 18809678 DOI: 10.1074/jbc.m804977200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The yeast pre-mRNA retention and splicing complex counteracts the escape of unspliced pre-mRNAs from the nucleus and activates splicing of a subset of Mer1p-dependent genes. A homologous complex is present in activated human spliceosomes. In many components of the spliceosome, RNA recognition motifs (RRMs) serve as versatile protein-RNA or protein-protein interaction platforms. Here, we show that in the retention and splicing complex, an atypical RRM of the Snu17p (small nuclear ribonucleoprotein-associated protein 17) subunit acts as a scaffold that organizes the other two constituents, Bud13p (bud site selection 13) and Pml1p (pre-mRNA leakage 1). GST pull-down experiments and size exclusion chromatography revealed that Snu17p constitutes the central platform of the complex, whereas Bud13p and Pml1p do not interact with each other. Fluorimetric structure probing showed the entire Bud13p and the N-terminal third of Pml1p to be natively disordered in isolation. Mutational analysis and tryptophan fluorescence confirmed that a conserved tryptophan-containing motif in the C terminus of Bud13p binds to the core RRM of Snu17p, whereas a different interaction surface encompassing a C-terminal extension of the Snu17p RRM is required to bind an N-terminal peptide of Pml1p. Isothermal titration calorimetry revealed 1:1 interaction stoichiometries, large negative binding entropies, and dissociation constants in the low nanomolar and micromolar ranges for the Snu17p-Bud13p and the Snu17p-Pml1p interactions, respectively. Our results demonstrate that the noncanonical Snu17p RRM concomitantly binds multiple ligand proteins via short, intrinsically unstructured peptide epitopes and thereby acts as a platform that displays functional modules of the ligands, such as a forkhead-associated domain of Pml1p and a conserved polylysine motif of Bud13p.
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Affiliation(s)
- Simon Trowitzsch
- Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany
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149
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Cléry A, Blatter M, Allain FHT. RNA recognition motifs: boring? Not quite. Curr Opin Struct Biol 2008; 18:290-8. [PMID: 18515081 DOI: 10.1016/j.sbi.2008.04.002] [Citation(s) in RCA: 460] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 04/09/2008] [Indexed: 01/10/2023]
Abstract
The RNA recognition motif (RRM) is one of the most abundant protein domains in eukaryotes. While the structure of this domain is well characterized by the packing of two alpha-helices on a four-stranded beta-sheet, the mode of protein and RNA recognition by RRMs is not clear owing to the high variability of these interactions. Here we report recent structural data on RRM-RNA and RRM-protein interactions showing the ability of this domain to modulate its binding affinity and specificity using each of its constitutive elements (beta-strands, loops, alpha-helices). The extreme structural versatility of the RRM interactions explains why RRM-containing proteins have so diverse biological functions.
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Affiliation(s)
- Antoine Cléry
- Institute for Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
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150
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Abstract
The nuclear lamina represents a protein network required for nuclear structure and function. One family of lamina proteins is defined by an approximately 40-aa LAP2, Emerin, and MAN1 (LEM) domain (LEM-D) that binds the nonspecific DNA-binding protein, barrier-to-autointegration factor (BAF). Through interactions with BAF, LEM-D proteins serve as a bridge between chromosomes and the nuclear envelope. Mutations in genes encoding LEM-D proteins cause human laminopathies that are associated with tissue-restricted pathologies. Drosophila has five genes that encode proteins with LEM homology. Using yeast two-hybrid analyses, we demonstrate that four encode proteins that bind Drosophila (d)BAF. In addition to dBAF, dMAN1 associates with lamins, the LEM-D protein Bocksbeutel, and the receptor-regulated Smads, demonstrating parallel protein interactions with vertebrate homologs. P-element mobilization was used to generate null dMAN1 alleles. These mutants showed decreased viability, with surviving adults displaying male sterility, decreased female fertility, wing patterning and positioning defects, flightlessness, and locomotion difficulties that became more severe with age. Increased phospho-Smad staining in dMAN1 mutant wing discs is consistent with a role in transforming growth factor (TGF)-beta/bone morphogenic protein (BMP) signaling. The tissue-specific, age-enhanced dMAN1 mutant phenotypes are reminiscent of human laminopathies, suggesting that studies in Drosophila will provide insights into lamina dysfunction associated with disease.
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