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Hsiao HHT, Crichlow GV, Murphy JW, Folta-Stogniew EJ, Lolis EJ, Braddock DT. Unraveling the mechanism of recognition of the 3' splice site of the adenovirus major late promoter intron by the alternative splicing factor PUF60. PLoS One 2020; 15:e0242725. [PMID: 33253191 PMCID: PMC7703929 DOI: 10.1371/journal.pone.0242725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 11/06/2020] [Indexed: 11/18/2022] Open
Abstract
Pre-mRNA splicing is critical for achieving required amounts of a transcript at a given time and for regulating production of encoded protein. A given pre-mRNA may be spliced in many ways, or not at all, giving rise to multiple gene products. Numerous splicing factors are recruited to pre-mRNA splice sites to ensure proper splicing. One such factor, the 60 kDa poly(U)-binding splicing factor (PUF60), is recruited to sites that are not always spliced, but rather function as alternative splice sites. In this study, we characterized the interaction of PUF60 with a splice site from the adenovirus major late promoter (the AdML 3' splice site, AdML3’). We found that the PUF60–AdML3’ dissociation constants are in the micromolar range, with the binding affinity predominantly provided by PUF60’s two central RNA recognition motifs (RRMs). A 1.95 Å crystal structure of the two PUF60 RRMs in complex with AdML3’ revealed a dimeric organization placing two stretches of nucleic acid tracts in opposing directionalities, which can cause looping of nucleic acid and explain how PUF60 affects pre-mRNA geometry to effect splicing. Solution characterization of this complex by light-scattering and UV/Vis spectroscopy suggested a potential 2:1 (PUF602:AdML3’) stoichiometry, consistent with the crystal structure. This work defines the sequence specificity of the alternative splicing factor PUF60 at the pre-mRNA 3’ splice site. Our observations suggest that control of pre-mRNA directionality is important in the early stage of spliceosome assembly, and advance our understanding of the molecular mechanism by which alternative and constitutive splicing factors differentiate among 3’ splice sites.
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Affiliation(s)
- Hsin-hao T. Hsiao
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Gregg V. Crichlow
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - James W. Murphy
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ewa J. Folta-Stogniew
- W.M. Keck Biotechnology Research Laboratory, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Elias J. Lolis
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Demetrios T. Braddock
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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2
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The biological function and clinical significance of SF3B1 mutations in cancer. Biomark Res 2020; 8:38. [PMID: 32905346 PMCID: PMC7469106 DOI: 10.1186/s40364-020-00220-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 08/24/2020] [Indexed: 02/07/2023] Open
Abstract
Spliceosome mutations have become the most interesting mutations detected in human cancer in recent years. The spliceosome, a large, dynamic multimegadalton small nuclear ribonucleoprotein composed of small nuclear RNAs associated with proteins, is responsible for removing introns from precursor mRNA (premRNA) and generating mature, spliced mRNAs. SF3B1 is the largest subunit of the spliceosome factor 3b (SF3B) complex, which is a core component of spliceosomes. Recurrent somatic mutations in SF3B1 have been detected in human cancers, including hematological malignancies and solid tumors, and indicated to be related to patient prognosis. This review summarizes the research progress of SF3B1 mutations in cancer, including SF3B1 mutations in the HEAT domain, the multiple roles and aberrant splicing events of SF3B1 mutations in the pathogenesis of tumors, and changes in mutated cancer cells regarding sensitivity to SF3B small-molecule inhibitors. In addition, the potential of SF3B1 or its mutations to serve as biomarkers or therapeutic targets in cancer is discussed. The accumulated knowledge about SF3B1 mutations in cancer provides critical insight into the integral role the SF3B1 protein plays in mRNA splicing and suggests new targets for anticancer therapy.
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3
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Diarra Dit Konté N, Krepl M, Damberger FF, Ripin N, Duss O, Šponer J, Allain FHT. Aromatic side-chain conformational switch on the surface of the RNA Recognition Motif enables RNA discrimination. Nat Commun 2017; 8:654. [PMID: 28935965 PMCID: PMC5608764 DOI: 10.1038/s41467-017-00631-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 07/16/2017] [Indexed: 11/13/2022] Open
Abstract
The cyclooxygenase-2 is a pro-inflammatory and cancer marker, whose mRNA stability and translation is regulated by the CUG-binding protein 2 interacting with AU-rich sequences in the 3' untranslated region. Here, we present the solution NMR structure of CUG-binding protein 2 RRM3 in complex with 5'-UUUAA-3' originating from the COX-2 3'-UTR. We show that RRM3 uses the same binding surface and protein moieties to interact with AU- and UG-rich RNA motifs, binding with low and high affinity, respectively. Using NMR spectroscopy, isothermal titration calorimetry and molecular dynamics simulations, we demonstrate that distinct sub-states characterized by different aromatic side-chain conformations at the RNA-binding surface allow for high- or low-affinity binding with functional implications. This study highlights a mechanism for RNA discrimination possibly common to multiple RRMs as several prominent members display a similar rearrangement of aromatic residues upon binding their targets.The RNA Recognition Motif (RRM) is the most ubiquitous RNA binding domain. Here the authors combined NMR and molecular dynamics simulations and show that the RRM RNA binding surface exists in different states and that a conformational switch of aromatic side-chains fine-tunes sequence specific binding affinities.
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Affiliation(s)
- Nana Diarra Dit Konté
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, HPP L 14.1 Hönggerbergring 64, 8093, Zürich, Switzerland
| | - Miroslav Krepl
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65, Brno, Czech Republic
- Department of Physical Chemistry, Faculty of Science, Regional Centre of Advanced Technologies and Materials, Palacky University Olomouc, 17.listopadu 12, 771 46, Olomouc, Czech Republic
| | - Fred F Damberger
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, HPP L 14.1 Hönggerbergring 64, 8093, Zürich, Switzerland
| | - Nina Ripin
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, HPP L 14.1 Hönggerbergring 64, 8093, Zürich, Switzerland
| | - Olivier Duss
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, HPP L 14.1 Hönggerbergring 64, 8093, Zürich, Switzerland
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, MB-33 10550 North Torrey Pines Road, La Jolla, California, 92037, USA
- Department of Structural Biology, Stanford University, Stanford, CA, 94305, USA
| | - Jiří Šponer
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65, Brno, Czech Republic
- Department of Physical Chemistry, Faculty of Science, Regional Centre of Advanced Technologies and Materials, Palacky University Olomouc, 17.listopadu 12, 771 46, Olomouc, Czech Republic
| | - Frédéric H-T Allain
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, HPP L 14.1 Hönggerbergring 64, 8093, Zürich, Switzerland.
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4
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Glasser E, Agrawal AA, Jenkins JL, Kielkopf CL. Cancer-Associated Mutations Mapped on High-Resolution Structures of the U2AF2 RNA Recognition Motifs. Biochemistry 2017; 56:4757-4761. [PMID: 28850223 DOI: 10.1021/acs.biochem.7b00551] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Acquired point mutations of pre-mRNA splicing factors recur among cancers, leukemias, and related neoplasms. Several studies have established that somatic mutations of a U2AF1 subunit, which normally recognizes 3' splice site junctions, recur among myelodysplastic syndromes. The U2AF2 splicing factor recognizes polypyrimidine signals that precede most 3' splice sites as a heterodimer with U2AF1. In contrast with those of the well-studied U2AF1 subunit, descriptions of cancer-relevant U2AF2 mutations and their structural relationships are lacking. Here, we survey databases of cancer-associated mutations and identify recurring missense mutations in the U2AF2 gene. We determine ultra-high-resolution structures of the U2AF2 RNA recognition motifs (RRM1 and RRM2) at 1.1 Å resolution and map the structural locations of the mutated U2AF2 residues. Comparison with prior, lower-resolution structures of the tandem U2AF2 RRMs in the RNA-bound and apo states reveals clusters of cancer-associated mutations at the U2AF2 RRM-RNA or apo-RRM1-RRM2 interfaces. Although the role of U2AF2 mutations in malignant transformation remains uncertain, our results show that cancer-associated mutations correlate with functionally important surfaces of the U2AF2 splicing factor.
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Affiliation(s)
- Eliezra Glasser
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States
| | - Anant A Agrawal
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States
| | - Jermaine L Jenkins
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States
| | - Clara L Kielkopf
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, New York 14642, United States
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5
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Basu S, Bahadur RP. A structural perspective of RNA recognition by intrinsically disordered proteins. Cell Mol Life Sci 2016; 73:4075-84. [PMID: 27229125 PMCID: PMC7079799 DOI: 10.1007/s00018-016-2283-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/13/2016] [Accepted: 05/20/2016] [Indexed: 11/24/2022]
Abstract
Protein-RNA recognition is essential for gene expression and its regulation, which is indispensable for the survival of the living organism at one hand, on the other hand, misregulation of this recognition may lead to their extinction. Polymorphic conformation of both the interacting partners is a characteristic feature of such molecular recognition that promotes the assembly. Many RNA binding proteins (RBP) or regions in them are found to be intrinsically disordered, and this property helps them to play a central role in the regulatory processes. Sequence composition and the length of the flexible linkers between RNA binding domains in RBPs are crucial in making significant contacts with its partner RNA. Polymorphic conformations of RBPs can provide thermodynamic advantage to its binding partner while acting as a chaperone. Prolonged extensions of the disordered regions in RBPs also contribute to the stability of the large cellular machines including ribosome and viral assemblies. The involvement of these disordered regions in most of the significant cellular processes makes RBPs highly associated with various human diseases that arise due to their misregulation.
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Affiliation(s)
- Sushmita Basu
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Ranjit Prasad Bahadur
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
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6
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Basu S, Bahadur RP. A structural perspective of RNA recognition by intrinsically disordered proteins. CELLULAR AND MOLECULAR LIFE SCIENCES : CMLS 2016. [PMID: 27229125 DOI: 10.1007/s00018‐016‐2283‐1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Protein-RNA recognition is essential for gene expression and its regulation, which is indispensable for the survival of the living organism at one hand, on the other hand, misregulation of this recognition may lead to their extinction. Polymorphic conformation of both the interacting partners is a characteristic feature of such molecular recognition that promotes the assembly. Many RNA binding proteins (RBP) or regions in them are found to be intrinsically disordered, and this property helps them to play a central role in the regulatory processes. Sequence composition and the length of the flexible linkers between RNA binding domains in RBPs are crucial in making significant contacts with its partner RNA. Polymorphic conformations of RBPs can provide thermodynamic advantage to its binding partner while acting as a chaperone. Prolonged extensions of the disordered regions in RBPs also contribute to the stability of the large cellular machines including ribosome and viral assemblies. The involvement of these disordered regions in most of the significant cellular processes makes RBPs highly associated with various human diseases that arise due to their misregulation.
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Affiliation(s)
- Sushmita Basu
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Ranjit Prasad Bahadur
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
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7
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Papasaikas P, Valcárcel J. The Spliceosome: The Ultimate RNA Chaperone and Sculptor. Trends Biochem Sci 2015; 41:33-45. [PMID: 26682498 DOI: 10.1016/j.tibs.2015.11.003] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/02/2015] [Accepted: 11/06/2015] [Indexed: 01/08/2023]
Abstract
The spliceosome, one of the most complex machineries of eukaryotic cells, removes intronic sequences from primary transcripts to generate functional messenger and long noncoding RNAs (lncRNA). Genetic, biochemical, and structural data reveal that the spliceosome is an RNA-based enzyme. Striking mechanistic and structural similarities strongly argue that pre-mRNA introns originated from self-catalytic group II ribozymes. However, in the spliceosome, protein components organize and activate the catalytic-site RNAs, and recognize and pair together splice sites at intron boundaries. The spliceosome is a dynamic, reversible, and flexible machine that chaperones small nuclear (sn) RNAs and a variety of pre-mRNA sequences into conformations that enable intron removal. This malleability likely contributes to the regulation of alternative splicing, a prevalent process contributing to cell differentiation, homeostasis, and disease.
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Affiliation(s)
- Panagiotis Papasaikas
- Centre de Regulació Genòmica, The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu-Fabra, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Juan Valcárcel
- Centre de Regulació Genòmica, The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu-Fabra, Dr. Aiguader 88, 08003 Barcelona, Spain; ICREA, Passeig Lluis Companys 23, 08010 Barcelona, Spain.
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8
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Huang JR, Warner LR, Sanchez C, Gabel F, Madl T, Mackereth CD, Sattler M, Blackledge M. Transient electrostatic interactions dominate the conformational equilibrium sampled by multidomain splicing factor U2AF65: a combined NMR and SAXS study. J Am Chem Soc 2014; 136:7068-76. [PMID: 24734879 DOI: 10.1021/ja502030n] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Multidomain proteins containing intrinsically disordered linkers exhibit large-scale dynamic modes that play key roles in a multitude of molecular recognition and signaling processes. Here, we determine the conformational space sampled by the multidomain splicing factor U2AF65 using complementary nuclear magnetic resonance spectroscopy and small-angle scattering data. Available degrees of conformational freedom are initially stochastically sampled and experimental data then used to delineate the potential energy landscape in terms of statistical probability. The spatial distribution of U2AF65 conformations is found to be highly anisotropic, comprising significantly populated interdomain contacts that appear to be electrostatic in origin. This hypothesis is supported by the reduction of signature PREs reporting on expected interfaces with increasing salt concentration. The described spatial distribution reveals the complete spectrum of the unbound forms of U2AF65 that coexist with the small percentage of a preformed RNA-bound domain arrangement required for polypyrimidine-tract recognition by conformational selection. More generally, the proposed approach to describing conformational equilibria of multidomain proteins can be further combined with other experimental data that are sensitive to domain dynamics.
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Affiliation(s)
- Jie-rong Huang
- University Grenoble Alpes, ‡CNRS, and §CEA, Protein Dynamics and Flexibility, Institut de Biologie Structurale , 38000 Grenoble, France
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9
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Duss O, Michel E, Diarra dit Konté N, Schubert M, Allain FHT. Molecular basis for the wide range of affinity found in Csr/Rsm protein-RNA recognition. Nucleic Acids Res 2014; 42:5332-46. [PMID: 24561806 PMCID: PMC4005645 DOI: 10.1093/nar/gku141] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The carbon storage regulator/regulator of secondary metabolism (Csr/Rsm) type of small non-coding RNAs (sRNAs) is widespread throughout bacteria and acts by sequestering the global translation repressor protein CsrA/RsmE from the ribosome binding site of a subset of mRNAs. Although we have previously described the molecular basis of a high affinity RNA target bound to RsmE, it remains unknown how other lower affinity targets are recognized by the same protein. Here, we have determined the nuclear magnetic resonance solution structures of five separate GGA binding motifs of the sRNA RsmZ of Pseudomonas fluorescens in complex with RsmE. The structures explain how the variation of sequence and structural context of the GGA binding motifs modulate the binding affinity for RsmE by five orders of magnitude (∼10 nM to ∼3 mM, Kd). Furthermore, we see that conformational adaptation of protein side-chains and RNA enable recognition of different RNA sequences by the same protein contributing to binding affinity without conferring specificity. Overall, our findings illustrate how the variability in the Csr/Rsm protein-RNA recognition allows a fine-tuning of the competition between mRNAs and sRNAs for the CsrA/RsmE protein.
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Affiliation(s)
- Olivier Duss
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
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10
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Inaba S, Fukada H, Ikegami T, Oda M. Thermodynamic effects of multiple protein conformations on stability and DNA binding. Arch Biochem Biophys 2013; 537:225-32. [DOI: 10.1016/j.abb.2013.07.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 07/09/2013] [Accepted: 07/12/2013] [Indexed: 10/26/2022]
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11
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Jenkins JL, Agrawal AA, Gupta A, Green MR, Kielkopf CL. U2AF65 adapts to diverse pre-mRNA splice sites through conformational selection of specific and promiscuous RNA recognition motifs. Nucleic Acids Res 2013; 41:3859-73. [PMID: 23376934 PMCID: PMC3616741 DOI: 10.1093/nar/gkt046] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Degenerate splice site sequences mark the intron boundaries of pre-mRNA transcripts in multicellular eukaryotes. The essential pre-mRNA splicing factor U2AF65 is faced with the paradoxical tasks of accurately targeting polypyrimidine (Py) tracts preceding 3′ splice sites while adapting to both cytidine and uridine nucleotides with nearly equivalent frequencies. To understand how U2AF65 recognizes degenerate Py tracts, we determined six crystal structures of human U2AF65 bound to cytidine-containing Py tracts. As deoxy-ribose backbones were required for co-crystallization with these Py tracts, we also determined two baseline structures of U2AF65 bound to the deoxy-uridine counterparts and compared the original, RNA-bound structure. Local structural changes suggest that the N-terminal RNA recognition motif 1 (RRM1) is more promiscuous for cytosine-containing Py tracts than the C-terminal RRM2. These structural differences between the RRMs were reinforced by the specificities of wild-type and site-directed mutant U2AF65 for region-dependent cytosine- and uracil-containing RNA sites. Small-angle X-ray scattering analyses further demonstrated that Py tract variations select distinct inter-RRM spacings from a pre-existing ensemble of U2AF65 conformations. Our results highlight both local and global conformational selection as a means for universal 3′ splice site recognition by U2AF65.
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Affiliation(s)
- Jermaine L Jenkins
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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12
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Mackereth CD, Sattler M. Dynamics in multi-domain protein recognition of RNA. Curr Opin Struct Biol 2012; 22:287-96. [DOI: 10.1016/j.sbi.2012.03.013] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 03/25/2012] [Indexed: 12/28/2022]
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13
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Boehr DD. Promiscuity in protein-RNA interactions: conformational ensembles facilitate molecular recognition in the spliceosome: conformational diversity in U2AF⁶⁵ facilitates binding to diverse RNA sequences. Bioessays 2011; 34:174-80. [PMID: 22144099 DOI: 10.1002/bies.201100152] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Here I discuss findings that suggest a universal mechanism for proteins (and RNA) to recognize and interact with various binding partners by selectively binding to different conformations that pre-exist in the free protein's conformational ensemble. The tandem RNA recognition motif domains of splicing factor U2AF⁶⁵ fluctuate in solution between a predominately closed conformation in which the RNA binding site of one of the domains is blocked, and a lowly populated open conformation in which both RNA binding pockets are accessible. RNA binding to U2AF⁶⁵ may thus occur through the weakly populated open conformation, and the binding interaction stabilizes the open conformation. The conformational diversity observed in U2AF⁶⁵ might also facilitate binding to diverse RNA sequences as found in the polypyrimidine tracts that help define 3' splice sites. Similar binding pathways in other systems have important consequences in biological regulation, molecular evolution, and information storage.
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Affiliation(s)
- David D Boehr
- Department of Chemistry, The Pennsylvania State University, 240 Chemistry Building, University Park, PA, USA.
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14
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Reveal B, Garcia C, Ellington A, Macdonald PM. Multiple RNA binding domains of Bruno confer recognition of diverse binding sites for translational repression. RNA Biol 2011; 8:1047-60. [PMID: 21955496 DOI: 10.4161/rna.8.6.17542] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Bruno protein binds to multiple sites - BREs - in the oskar mRNA 3' UTR, thereby controlling oskar mRNA translation. Bruno also binds and regulates other mRNAs, although the binding sites have not yet been defined. Bruno has three RRM type RNA binding motifs, two near the amino terminus and an extended RRM at the C terminus. Two domains of Bruno, the first two RRMs (RRM1+2), and the extended RRM (RRM3+) - can each bind with specificity to the oskar mRNA regulatory regions; these and Bruno were used for in vitro selections. Anti-RRM3+ aptamers include long, highly constrained motifs, including one corresponding to the previously identified BRE. Anti-RRM1+2 aptamers lack constrained motifs, but are biased towards classes of short and variable sequences. Bruno itself selects for several motifs, including some of those bound by RRM3+. We propose that the different RNA binding domains allow for combinatorial binding, with extended Bruno binding sites assembled from sequences bound by the individual domains. Examples of such sites were identified in known targets of Bruno, and shown to confer Bruno-dependent translational repression in vivo. Other proteins with multiple RRMs may employ combinatorial binding to achieve high levels of specificity and affinity.
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Affiliation(s)
- Brad Reveal
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, TX, USA
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15
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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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16
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Sperling J, Azubel M, Sperling R. Structure and function of the Pre-mRNA splicing machine. Structure 2009; 16:1605-15. [PMID: 19000813 DOI: 10.1016/j.str.2008.08.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 08/22/2008] [Accepted: 08/27/2008] [Indexed: 12/14/2022]
Abstract
Most eukaryotic pre-mRNAs contain non-coding sequences (introns) that must be removed in order to accurately place the coding sequences (exons) in the correct reading frame. This critical regulatory pre-mRNA splicing event is fundamental in development and cancer. It occurs within a mega-Dalton multicomponent machine composed of RNA and proteins, which undergoes dynamic changes in RNA-RNA, RNA-protein, and protein-protein interactions during the splicing reaction. Recent years have seen progress in functional and structural analyses of the splicing machine and its subcomponents, and this review is focused on structural aspects of the pre-mRNA splicing machine and their mechanistic implications on the splicing of multi-intronic pre-mRNAs. It brings together, in a comparative manner, structural information on spliceosomes and their intermediates in the stepwise assembly process in vitro, and on the preformed supraspliceosomes, which are isolated from living cell nuclei, with a view of portraying a consistent picture.
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Affiliation(s)
- Joseph Sperling
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
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17
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Jurica MS. Detailed close-ups and the big picture of spliceosomes. Curr Opin Struct Biol 2008; 18:315-20. [PMID: 18550358 DOI: 10.1016/j.sbi.2008.05.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 05/08/2008] [Accepted: 05/13/2008] [Indexed: 02/04/2023]
Abstract
The spliceosome is the huge macromolecular assembly responsible for the removal of introns from pre-mRNA transcripts. The size and complexity of this dynamic cellular machine dictate that structural analysis of the spliceosome is best served by a combination of techniques. Electron microscopy is providing a more global, albeit less detailed, view of spliceosome assemblies. X-ray crystallographers and NMR spectroscopists are steadily reporting more atomic resolution structures of individual spliceosome components and fragments. Increasingly, structures of these individual pieces in complex with binding partners are yielding insights into the interfaces that hold the entire spliceosome assembly together. Although the information arising from the various structural studies of splicing machinery has not yet fully converged into a complete model, we can expect that a detailed understanding of spliceosome structure will arise at the juncture of structural and computational modeling methods.
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Affiliation(s)
- Melissa S Jurica
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, CA 95064, United States.
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Swenson MC, Paranawithana SR, Miller PS, Kielkopf CL. Structure of a DNA repair substrate containing an alkyl interstrand cross-link at 1.65 A resolution. Biochemistry 2007; 46:4545-53. [PMID: 17375936 PMCID: PMC2625308 DOI: 10.1021/bi700109r] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Chemotherapeutic alkylating agents, such as bifunctional nitrogen mustards and cisplatins, generate interstrand DNA cross-links that inhibit cell proliferation by arresting DNA transcription and replication. A synthetic N4C-ethyl-N4C interstrand cross-link between opposing cytidines mimics the DNA damage produced by this class of clinically important compounds and can be synthesized in large quantities to study the repair, physical properties, and structures of these DNA adducts. The X-ray structure of a DNA duplex d(CCAAC*GTTGG)2 containing a synthetic N4C-ethyl-N4C interstrand cross-link between the cytosines of the central CpG step (*) has been determined at 1.65 A resolution. This structure reveals that the ethyl cross-link in the CpG major groove does not significantly disrupt the B-form DNA helix. Comparison of the N4C-ethyl-N4C cross-linked structure with the structure of an un-cross-linked oligonucleotide of the same sequence reveals that the cross-link selectively stabilizes a preexisting alternative conformation. The conformation preferred by the cross-linked DNA is constrained by the geometry of the ethyl group bridging the cytosine amines. Characteristics of the cross-linked CpG step include subtle differences in the roll of the base pairs, optimized Watson-Crick hydrogen bonds, and loss of a divalent cation binding site. Given that the N4C-ethyl-N4C cross-link stabilizes a preexisting conformation of the CpG step, this synthetically accessible substrate presents an ideal model system for studying the genomic effects of covalently coupling the DNA strands, independent of gross alterations in DNA structure.
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Affiliation(s)
- Matthew C Swenson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA
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