1
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Plewka P, Szczesniak MW, Stepien A, Pasieka R, Wanowska E, Makalowska I, Raczynska KD. Novel function of U7 snRNA in the repression of HERV1/LTR12s and lincRNAs in human cells. Nucleic Acids Res 2024:gkae738. [PMID: 39189459 DOI: 10.1093/nar/gkae738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 08/07/2024] [Accepted: 08/19/2024] [Indexed: 08/28/2024] Open
Abstract
U7 snRNA is part of the U7 snRNP complex, required for the 3' end processing of replication-dependent histone pre-mRNAs in S phase of the cell cycle. Here, we show that U7 snRNA plays another function in inhibiting the expression of a subset of long terminal repeats of human endogenous retroviruses (HERV1/LTR12s) and LTR12-containing long intergenic noncoding RNAs (lincRNAs), both bearing sequence motifs that perfectly match the 5' end of U7 snRNA. We demonstrate that U7 snRNA inhibits LTR12 and lincRNA transcription and propose a mechanism in which U7 snRNA hampers the binding/activity of the NF-Y transcription factor to CCAAT motifs within LTR12 elements. Thereby, U7 snRNA plays a protective role in maintaining the silencing of deleterious genetic elements in selected types of cells.
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Affiliation(s)
- Patrycja Plewka
- Department of Gene Expression, Laboratory of RNA Processing, Institute of Molecular Biology and Biotechnology, Faculty of Biology and Center for Advanced Technology, Adam Mickiewicz University, Poznan, Poland
| | - Michal W Szczesniak
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Agata Stepien
- Department of Gene Expression, Laboratory of RNA Processing, Institute of Molecular Biology and Biotechnology, Faculty of Biology and Center for Advanced Technology, Adam Mickiewicz University, Poznan, Poland
| | - Robert Pasieka
- Department of Gene Expression, Laboratory of RNA Processing, Institute of Molecular Biology and Biotechnology, Faculty of Biology and Center for Advanced Technology, Adam Mickiewicz University, Poznan, Poland
| | - Elzbieta Wanowska
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Izabela Makalowska
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Katarzyna Dorota Raczynska
- Department of Gene Expression, Laboratory of RNA Processing, Institute of Molecular Biology and Biotechnology, Faculty of Biology and Center for Advanced Technology, Adam Mickiewicz University, Poznan, Poland
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2
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Cortazar MA, Erickson B, Fong N, Pradhan SJ, Ntini E, Bentley DL. Xrn2 substrate mapping identifies torpedo loading sites and extensive premature termination of RNA pol II transcription. Genes Dev 2022; 36:1062-1078. [PMID: 36396340 PMCID: PMC9744234 DOI: 10.1101/gad.350004.122] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/31/2022] [Indexed: 11/19/2022]
Abstract
The exonuclease torpedo Xrn2 loads onto nascent RNA 5'-PO4 ends and chases down pol II to promote termination downstream from polyA sites. We report that Xrn2 is recruited to preinitiation complexes and "travels" to 3' ends of genes. Mapping of 5'-PO4 ends in nascent RNA identified Xrn2 loading sites stabilized by an active site mutant, Xrn2(D235A). Xrn2 loading sites are approximately two to 20 bases downstream from where CPSF73 cleaves at polyA sites and histone 3' ends. We propose that processing of all mRNA 3' ends comprises cleavage and limited 5'-3' trimming by CPSF73, followed by handoff to Xrn2. A similar handoff occurs at tRNA 3' ends, where cotranscriptional RNase Z cleavage generates novel Xrn2 substrates. Exonuclease-dead Xrn2 increased transcription in 3' flanking regions by inhibiting polyA site-dependent termination. Surprisingly, the mutant Xrn2 also rescued transcription in promoter-proximal regions to the same extent as in 3' flanking regions. eNET-seq revealed Xrn2-mediated degradation of sense and antisense nascent RNA within a few bases of the TSS, where 5'-PO4 ends may be generated by decapping or endonucleolytic cleavage. These results suggest that a major fraction of pol II complexes terminates prematurely close to the start site under normal conditions by an Xrn2-mediated torpedo mechanism.
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Affiliation(s)
- Michael A. Cortazar
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Benjamin Erickson
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Nova Fong
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Sarala J. Pradhan
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Evgenia Ntini
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology–Hellas (FORTH), Heraklion GR-70013, Greece
| | - David L. Bentley
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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3
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U7 deciphered: the mechanism that forms the unusual 3' end of metazoan replication-dependent histone mRNAs. Biochem Soc Trans 2021; 49:2229-2240. [PMID: 34351387 DOI: 10.1042/bst20210323] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/17/2022]
Abstract
In animal cells, replication-dependent histone mRNAs end with a highly conserved stem-loop structure followed by a 4- to 5-nucleotide single-stranded tail. This unique 3' end distinguishes replication-dependent histone mRNAs from all other eukaryotic mRNAs, which end with a poly(A) tail produced by the canonical 3'-end processing mechanism of cleavage and polyadenylation. The pioneering studies of Max Birnstiel's group demonstrated nearly 40 years ago that the unique 3' end of animal replication-dependent histone mRNAs is generated by a distinct processing mechanism, whereby histone mRNA precursors are cleaved downstream of the stem-loop, but this cleavage is not followed by polyadenylation. The key role is played by the U7 snRNP, a complex of a ∼60 nucleotide U7 snRNA and many proteins. Some of these proteins, including the enzymatic component CPSF73, are shared with the canonical cleavage and polyadenylation machinery, justifying the view that the two metazoan pre-mRNA 3'-end processing mechanisms have a common evolutionary origin. The studies on U7 snRNP culminated in the recent breakthrough of reconstituting an entirely recombinant human machinery that is capable of accurately cleaving histone pre-mRNAs, and determining its structure in complex with a pre-mRNA substrate (with 13 proteins and two RNAs) that is poised for the cleavage reaction. The structure uncovered an unanticipated network of interactions within the U7 snRNP and a remarkable mechanism of activating catalytically dormant CPSF73 for the cleavage. This work provides a conceptual framework for understanding other eukaryotic 3'-end processing machineries.
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4
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Sun Y, Zhang Y, Aik WS, Yang XC, Marzluff WF, Walz T, Dominski Z, Tong L. Structure of an active human histone pre-mRNA 3'-end processing machinery. Science 2020; 367:700-703. [PMID: 32029631 DOI: 10.1126/science.aaz7758] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/31/2019] [Indexed: 01/10/2023]
Abstract
The 3'-end processing machinery for metazoan replication-dependent histone precursor messenger RNAs (pre-mRNAs) contains the U7 small nuclear ribonucleoprotein and shares the key cleavage module with the canonical cleavage and polyadenylation machinery. We reconstituted an active human histone pre-mRNA processing machinery using 13 recombinant proteins and two RNAs and determined its structure by cryo-electron microscopy. The overall structure is highly asymmetrical and resembles an amphora with one long handle. We captured the pre-mRNA in the active site of the endonuclease, the 73-kilodalton subunit of the cleavage and polyadenylation specificity factor, poised for cleavage. The endonuclease and the entire cleavage module undergo extensive rearrangements for activation, triggered through the recognition of the duplex between the authentic pre-mRNA and U7 small nuclear RNA (snRNA). Our study also has notable implications for understanding canonical and snRNA 3'-end processing.
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Affiliation(s)
- Yadong Sun
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Yixiao Zhang
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY 10065, USA
| | - Wei Shen Aik
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Xiao-Cui Yang
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - William F Marzluff
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY 10065, USA.
| | - Zbigniew Dominski
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. .,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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5
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Bucholc K, Aik WS, Yang XC, Wang K, Zhou ZH, Dadlez M, Marzluff WF, Tong L, Dominski Z. Composition and processing activity of a semi-recombinant holo U7 snRNP. Nucleic Acids Res 2020; 48:1508-1530. [PMID: 31819999 PMCID: PMC7026596 DOI: 10.1093/nar/gkz1148] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 10/29/2019] [Accepted: 11/25/2019] [Indexed: 11/14/2022] Open
Abstract
In animal cells, replication-dependent histone pre-mRNAs are cleaved at the 3' end by U7 snRNP consisting of two core components: a ∼60-nucleotide U7 snRNA and a ring of seven proteins, with Lsm10 and Lsm11 replacing the spliceosomal SmD1 and SmD2. Lsm11 interacts with FLASH and together they recruit the endonuclease CPSF73 and other polyadenylation factors, forming catalytically active holo U7 snRNP. Here, we assembled core U7 snRNP bound to FLASH from recombinant components and analyzed its appearance by electron microscopy and ability to support histone pre-mRNA processing in the presence of polyadenylation factors from nuclear extracts. We demonstrate that semi-recombinant holo U7 snRNP reconstituted in this manner has the same composition and functional properties as endogenous U7 snRNP, and accurately cleaves histone pre-mRNAs in a reconstituted in vitro processing reaction. We also demonstrate that the U7-specific Sm ring assembles efficiently in vitro on a spliceosomal Sm site but the engineered U7 snRNP is functionally impaired. This approach offers a unique opportunity to study the importance of various regions in the Sm proteins and U7 snRNA in 3' end processing of histone pre-mRNAs.
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Affiliation(s)
- Katarzyna Bucholc
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Wei Shen Aik
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Xiao-Cui Yang
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kaituo Wang
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Z Hong Zhou
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Michał Dadlez
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.,Institute of Genetics and Biotechnology, Warsaw University, 02-106 Warsaw, Poland
| | - William F Marzluff
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Zbigniew Dominski
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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6
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Skrajna A, Yang XC, Dadlez M, Marzluff WF, Dominski Z. Protein composition of catalytically active U7-dependent processing complexes assembled on histone pre-mRNA containing biotin and a photo-cleavable linker. Nucleic Acids Res 2019. [PMID: 29529248 PMCID: PMC5961079 DOI: 10.1093/nar/gky133] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
3′ end cleavage of metazoan replication-dependent histone pre-mRNAs requires the multi-subunit holo-U7 snRNP and the stem–loop binding protein (SLBP). The exact composition of the U7 snRNP and details of SLBP function in processing remain unclear. To identify components of the U7 snRNP in an unbiased manner, we developed a novel approach for purifying processing complexes from Drosophila and mouse nuclear extracts. In this method, catalytically active processing complexes are assembled in vitro on a cleavage-resistant histone pre-mRNA containing biotin and a photo-sensitive linker, and eluted from streptavidin beads by UV irradiation for direct analysis by mass spectrometry. In the purified processing complexes, Drosophila and mouse U7 snRNP have a remarkably similar composition, always being associated with CPSF73, CPSF100, symplekin and CstF64. Many other proteins previously implicated in the U7-dependent processing are not present. Drosophila U7 snRNP bound to histone pre-mRNA in the absence of SLBP contains the same subset of polyadenylation factors but is catalytically inactive and addition of recombinant SLBP is sufficient to trigger cleavage. This result suggests that Drosophila SLBP promotes a structural rearrangement of the processing complex, resulting in juxtaposition of the CPSF73 endonuclease with the cleavage site in the pre-mRNA substrate.
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Affiliation(s)
- Aleksandra Skrajna
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Xiao-Cui Yang
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Michal Dadlez
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - William F Marzluff
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Zbigniew Dominski
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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7
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Pettinati I, Grzechnik P, Ribeiro de Almeida C, Brem J, McDonough MA, Dhir S, Proudfoot NJ, Schofield CJ. Biosynthesis of histone messenger RNA employs a specific 3' end endonuclease. eLife 2018; 7:39865. [PMID: 30507380 PMCID: PMC6303110 DOI: 10.7554/elife.39865] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/30/2018] [Indexed: 12/12/2022] Open
Abstract
Replication-dependent (RD) core histone mRNA produced during S-phase is the only known metazoan protein-coding mRNA presenting a 3' stem-loop instead of the otherwise universal polyA tail. A metallo β-lactamase (MBL) fold enzyme, cleavage and polyadenylation specificity factor 73 (CPSF73), is proposed to be the sole endonuclease responsible for 3' end processing of both mRNA classes. We report cellular, genetic, biochemical, substrate selectivity, and crystallographic studies providing evidence that an additional endoribonuclease, MBL domain containing protein 1 (MBLAC1), is selective for 3' processing of RD histone pre-mRNA during the S-phase of the cell cycle. Depletion of MBLAC1 in cells significantly affects cell cycle progression thus identifying MBLAC1 as a new type of S-phase-specific cancer target.
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Affiliation(s)
- Ilaria Pettinati
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Pawel Grzechnik
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | | | - Jurgen Brem
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | | | - Somdutta Dhir
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Nick J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
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8
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Mendiratta S, Gatto A, Almouzni G. Histone supply: Multitiered regulation ensures chromatin dynamics throughout the cell cycle. J Cell Biol 2018; 218:39-54. [PMID: 30257851 PMCID: PMC6314538 DOI: 10.1083/jcb.201807179] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/05/2018] [Accepted: 09/12/2018] [Indexed: 12/14/2022] Open
Abstract
Mendiratta et al. review the interplay between the different regulatory layers that affect the transcription and dynamics of distinct histone H3 variants along the cell cycle. As the building blocks of chromatin, histones are central to establish and maintain particular chromatin states associated with given cell fates. Importantly, histones exist as distinct variants whose expression and incorporation into chromatin are tightly regulated during the cell cycle. During S phase, specialized replicative histone variants ensure the bulk of the chromatinization of the duplicating genome. Other non-replicative histone variants deposited throughout the cell cycle at specific loci use pathways uncoupled from DNA synthesis. Here, we review the particular dynamics of expression, cellular transit, assembly, and disassembly of replicative and non-replicative forms of the histone H3. Beyond the role of histone variants in chromatin dynamics, we review our current knowledge concerning their distinct regulation to control their expression at different levels including transcription, posttranscriptional processing, and protein stability. In light of this unique regulation, we highlight situations where perturbations in histone balance may lead to cellular dysfunction and pathologies.
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Affiliation(s)
- Shweta Mendiratta
- Institut Curie, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, UMR3664, Equipe Labellisée Ligue contre le Cancer, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Centre National de la Recherche Scientifique, UMR3664, Paris, France
| | - Alberto Gatto
- Institut Curie, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, UMR3664, Equipe Labellisée Ligue contre le Cancer, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Centre National de la Recherche Scientifique, UMR3664, Paris, France
| | - Genevieve Almouzni
- Institut Curie, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, UMR3664, Equipe Labellisée Ligue contre le Cancer, Paris, France .,Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Centre National de la Recherche Scientifique, UMR3664, Paris, France
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9
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Molecular mechanisms for the regulation of histone mRNA stem-loop-binding protein by phosphorylation. Proc Natl Acad Sci U S A 2014; 111:E2937-46. [PMID: 25002523 DOI: 10.1073/pnas.1406381111] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Replication-dependent histone mRNAs end with a conserved stem loop that is recognized by stem-loop-binding protein (SLBP). The minimal RNA-processing domain of SLBP is phosphorylated at an internal threonine, and Drosophila SLBP (dSLBP) also is phosphorylated at four serines in its 18-aa C-terminal tail. We show that phosphorylation of dSLBP increases RNA-binding affinity dramatically, and we use structural and biophysical analyses of dSLBP and a crystal structure of human SLBP phosphorylated on the internal threonine to understand the striking improvement in RNA binding. Together these results suggest that, although the C-terminal tail of dSLBP does not contact the RNA, phosphorylation of the tail promotes SLBP conformations competent for RNA binding and thereby appears to reduce the entropic penalty for the association. Increased negative charge in this C-terminal tail balances positively charged residues, allowing a more compact ensemble of structures in the absence of RNA.
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10
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Sabath I, Skrajna A, Yang XC, Dadlez M, Marzluff WF, Dominski Z. 3'-End processing of histone pre-mRNAs in Drosophila: U7 snRNP is associated with FLASH and polyadenylation factors. RNA (NEW YORK, N.Y.) 2013; 19:1726-44. [PMID: 24145821 PMCID: PMC3884669 DOI: 10.1261/rna.040360.113] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
3'-End cleavage of animal replication-dependent histone pre-mRNAs is controlled by the U7 snRNP. Lsm11, the largest component of the U7-specific Sm ring, interacts with FLASH, and in mammalian nuclear extracts these two proteins form a platform that recruits the CPSF73 endonuclease and other polyadenylation factors to the U7 snRNP. FLASH is limiting, and the majority of the U7 snRNP in mammalian extracts exists as a core particle consisting of the U7 snRNA and the Sm ring. Here, we purified the U7 snRNP from Drosophila nuclear extracts and characterized its composition by mass spectrometry. In contrast to the mammalian U7 snRNP, a significant fraction of the Drosophila U7 snRNP contains endogenous FLASH and at least six subunits of the polyadenylation machinery: symplekin, CPSF73, CPSF100, CPSF160, WDR33, and CstF64. The same composite U7 snRNP is recruited to histone pre-mRNA for 3'-end processing. We identified a motif in Drosophila FLASH that is essential for the recruitment of the polyadenylation complex to the U7 snRNP and analyzed the role of other factors, including SLBP and Ars2, in 3'-end processing of Drosophila histone pre-mRNAs. SLBP that binds the upstream stem-loop structure likely recruits a yet-unidentified essential component(s) to the processing machinery. In contrast, Ars2, a protein previously shown to interact with FLASH in mammalian cells, is dispensable for processing in Drosophila. Our studies also demonstrate that Drosophila symplekin and three factors involved in cleavage and polyadenylation-CPSF, CstF, and CF Im-are present in Drosophila nuclear extracts in a stable supercomplex.
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Affiliation(s)
- Ivan Sabath
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Aleksandra Skrajna
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 00-901 Warsaw, Poland
| | - Xiao-cui Yang
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Michał Dadlez
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 00-901 Warsaw, Poland
- Institute of Genetics and Biotechnology, Warsaw University, 02-106 Warsaw, Poland
| | - William F. Marzluff
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Zbigniew Dominski
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Corresponding authorE-mail
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11
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Dominski Z, Carpousis AJ, Clouet-d'Orval B. Emergence of the β-CASP ribonucleases: highly conserved and ubiquitous metallo-enzymes involved in messenger RNA maturation and degradation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:532-51. [PMID: 23403287 DOI: 10.1016/j.bbagrm.2013.01.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/18/2013] [Accepted: 01/22/2013] [Indexed: 01/05/2023]
Abstract
The β-CASP ribonucleases, which are found in the three domains of life, have in common a core of 460 residues containing seven conserved sequence motifs involved in the tight binding of two catalytic zinc ions. A hallmark of these enzymes is their ability to catalyze both endo- and exo-ribonucleolytic degradation. Exo-ribonucleolytic degradation proceeds in the 5' to 3' direction and is sensitive to the phosphorylation state of the 5' end of a transcript. Recent phylogenomic analyses have shown that the β-CASP ribonucleases can be partitioned into two major subdivisions that correspond to orthologs of eukaryal CPSF73 and bacterial RNase J. We discuss the known functions of the CPSF73 and RNase J orthologs, their association into complexes, and their structure as it relates to mechanism of action. Eukaryal CPSF73 is part of a large multiprotein complex that is involved in the maturation of the 3' end of RNA Polymerase II transcripts and the polyadenylation of messenger RNA. RNase J1 and J2 are paralogs in Bacillus subtilis that are involved in the degradation of messenger RNA and the maturation of non-coding RNA. RNase J1 and J2 co-purify as a heteromeric complex and there is recent evidence that they interact with other enzymes to form a bacterial RNA degradosome. Finally, we speculate on the evolutionary origin of β-CASP ribonucleases and on their functions in Archaea. Orthologs of CPSF73 with endo- and exo-ribonuclease activity are strictly conserved throughout the archaea suggesting a role for these enzymes in the maturation and/or degradation of messenger RNA. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Affiliation(s)
- Zbigniew Dominski
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
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12
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A complex containing the CPSF73 endonuclease and other polyadenylation factors associates with U7 snRNP and is recruited to histone pre-mRNA for 3'-end processing. Mol Cell Biol 2012; 33:28-37. [PMID: 23071092 DOI: 10.1128/mcb.00653-12] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Animal replication-dependent histone pre-mRNAs are processed at the 3' end by endonucleolytic cleavage that is not followed by polyadenylation. The cleavage reaction is catalyzed by CPSF73 and depends on the U7 snRNP and its integral component, Lsm11. A critical role is also played by the 220-kDa protein FLASH, which interacts with Lsm11. Here we demonstrate that the N-terminal regions of these two proteins form a platform that tightly interacts with a unique combination of polyadenylation factors: symplekin, CstF64, and all CPSF subunits, including the endonuclease CPSF73. The interaction is inhibited by alterations in each component of the FLASH/Lsm11 complex, including point mutations in FLASH that are detrimental for processing. The same polyadenylation factors are associated with the endogenous U7 snRNP and are recruited in a U7-dependent manner to histone pre-mRNA. Collectively, our studies identify the molecular mechanism that recruits the CPSF73 endonuclease to histone pre-mRNAs, reveal an unexpected complexity of the U7 snRNP, and suggest that in animal cells polyadenylation factors assemble into two alternative complexes-one specifically crafted to generate polyadenylated mRNAs and the other to generate nonpolyadenylated histone mRNAs that end with the stem-loop.
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13
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Ruepp MD, Schümperli D, Barabino SML. mRNA 3' end processing and more--multiple functions of mammalian cleavage factor I-68. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 2:79-91. [PMID: 21956970 DOI: 10.1002/wrna.35] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The formation of defined 3(') ends is an important step in the biogenesis of mRNAs. In eukaryotic cells, all mRNA 3(') ends are generated by endonucleolytic cleavage of primary transcripts in reactions that are essentially posttranscriptional. Nevertheless, 3(') end formation is tightly connected to transcription in vivo, and a link with mRNA export to the cytoplasm has been postulated. Here, we briefly review the current knowledge about the two types of mRNA 3(') end processing reactions, cleavage/polyadenylation and histone RNA processing. We then focus on factors shared between these two reactions. In particular, we discuss evidence for new functions of the mammalian cleavage factor I subunit CF I(m) 68 in histone RNA 3(') processing and in the export of mature mRNAs from the nucleus to the cytoplasm.
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Affiliation(s)
- Marc-David Ruepp
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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14
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FLASH is required for the endonucleolytic cleavage of histone pre-mRNAs but is dispensable for the 5' exonucleolytic degradation of the downstream cleavage product. Mol Cell Biol 2011; 31:1492-502. [PMID: 21245389 DOI: 10.1128/mcb.00979-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
3'-end cleavage of histone pre-mRNAs is catalyzed by CPSF-73 and requires the interaction of two U7 snRNP-associated proteins, FLASH and Lsm11. Here, by using scanning mutagenesis we identify critical residues in human FLASH and Lsm11 that are involved in the interaction between these two proteins. We also demonstrate that mutations in the region of FLASH located between amino acids 50 and 99 do not affect binding of Lsm11. Interestingly, these mutations convert FLASH into an inhibitory protein that reduces in vitro processing efficiency of highly active nuclear extracts. Our results suggest that this region in FLASH in conjunction with Lsm11 is involved in recruiting a yet-unknown processing factor(s) to histone pre-mRNA. Following endonucleolytic cleavage of histone pre-mRNA, the downstream cleavage product (DCP) is degraded by the 5'-3' exonuclease activity of CPSF-73, which also depends on Lsm11. Strikingly, while cleavage of histone pre-mRNA is stimulated by FLASH and inhibited by both dominant negative mutants of FLASH and anti-FLASH antibodies, the 5'-3' degradation of the DCP is not affected. Thus, the recruitment of FLASH to the processing complex plays a critical role in activating the endonuclease mode of CPSF-73 but is dispensable for its 5'-3' exonuclease activity. These results suggest that CPSF-73, the catalytic component in both reactions, can be recruited to histone pre-mRNA largely in a manner independent of FLASH, possibly by a separate domain in Lsm11.
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15
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Dominski Z. The hunt for the 3' endonuclease. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:325-40. [PMID: 21935893 DOI: 10.1002/wrna.33] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pre-mRNAs are typically processed at the 3(') end by cleavage/polyadenylation. This is a two-step processing reaction initiated by endonucleolytic cleavage of pre-mRNAs downstream of the AAUAAA sequence or its variant, followed by extension of the newly generated 3(') end with a poly(A) tail. In metazoans, replication-dependent histone transcripts are cleaved by a different 3(') end processing mechanism that depends on the U7 small nuclear ribonucleoprotein and the polyadenylation step is omitted. Each of the two mechanisms occurs in a macromolecular assembly that primarily functions to juxtapose the scissile bond with the 3(') endonuclease. Remarkably, despite characterizing a number of processing factors, the identity of this most critical component remained elusive until recently. For cleavage coupled to polyadenylation, much needed help was offered by bioinformatics, which pointed to CPSF-73, a known processing factor required for both cleavage and polyadenylation, as the possible 3(') endonuclease. In silico structural analysis indicated that this protein is a member of the large metallo-β-lactamase family of hydrolytic enzymes and belongs to the β-CASP subfamily that includes several RNA and DNA-specific nucleases. Subsequent experimental studies supported the notion that CPSF-73 does function as the endonuclease in the formation of polyadenylated mRNAs, but some controversy still remains as a different cleavage and polyadenylation specificity factor (CPSF) subunit, CPSF-30, displays an endonuclease activity in vitro while recombinant CPSF-73 is inactive. Unexpectedly, CPSF-73 as the 3(') endonuclease in cleavage coupled to polyadenylation found a strong ally in U7-dependent processing of histone pre-mRNAs, which was shown to utilize the same protein as the cleaving enzyme. It thus seems likely that these two processing reactions evolved from a common mechanism, with CPSF-73 as the endonuclease.
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Affiliation(s)
- Zbigniew Dominski
- Department of Biochemistry and Biophysics and Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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16
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Kolev NG, Yario TA, Benson E, Steitz JA. Conserved motifs in both CPSF73 and CPSF100 are required to assemble the active endonuclease for histone mRNA 3'-end maturation. EMBO Rep 2008; 9:1013-8. [PMID: 18688255 DOI: 10.1038/embor.2008.146] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 06/18/2008] [Accepted: 07/01/2008] [Indexed: 12/29/2022] Open
Abstract
In eukaryotes, the process of messenger RNA 3'-end formation involves endonucleolytic cleavage of the transcript followed by synthesis of the poly(A) tail. The complex machinery involved in this maturation process contains two proteins of the metallo-beta-lactamase (MBL) superfamily, the 73 and 100 kDa subunits of the cleavage and polyadenylation specificity factor (CPSF). By using an in vitro system to assess point mutations in these two mammalian proteins, we found that conserved residues from the MBL motifs of both polypeptides are required for assembly of the endonuclease activity that cleaves histone pre-mRNAs. This indicates that CPSF73 and CPSF100 act together in the process of maturation of eukaryotic pre-messenger RNAs, similar to other members of the MBL family, RNases Z and J, which function as homodimers.
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Affiliation(s)
- Nikolay G Kolev
- Howard Hughes Medical Institute, Yale University, 295 Congress Avenue, New Haven, Connecticut 06519, USA
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17
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Dávila López M, Samuelsson T. Early evolution of histone mRNA 3' end processing. RNA (NEW YORK, N.Y.) 2008; 14:1-10. [PMID: 17998288 PMCID: PMC2151031 DOI: 10.1261/rna.782308] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Accepted: 09/27/2007] [Indexed: 05/20/2023]
Abstract
The replication-dependent histone mRNAs in metazoa are not polyadenylated, in contrast to the bulk of mRNA. Instead, they contain an RNA stem-loop (SL) structure close to the 3' end of the mature RNA, and this 3' end is generated by cleavage using a machinery involving the U7 snRNP and protein factors such as the stem-loop binding protein (SLBP). This machinery of 3' end processing is related to that of polyadenylation as protein components are shared between the systems. It is commonly believed that histone 3' end processing is restricted to metazoa and green algae. In contrast, polyadenylation is ubiquitous in Eukarya. However, using computational approaches, we have now identified components of histone 3' end processing in a number of protozoa. Thus, the histone mRNA stem-loop structure as well as the SLBP protein are present in many different protozoa, including Dictyostelium, alveolates, Trypanosoma, and Trichomonas. These results show that the histone 3' end processing machinery is more ancient than previously anticipated and can be traced to the root of the eukaryotic phylogenetic tree. We also identified histone mRNAs from both metazoa and protozoa that are polyadenylated but also contain the signals characteristic of histone 3' end processing. These results provide further evidence that some histone genes are regulated at the level of 3' end processing to produce either polyadenylated RNAs or RNAs with the 3' end characteristic of replication-dependent histone mRNAs.
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Affiliation(s)
- Marcela Dávila López
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy at Göteborg University, SE-405 30 Göteborg, Sweden
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18
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Dominski Z. Nucleases of the metallo-beta-lactamase family and their role in DNA and RNA metabolism. Crit Rev Biochem Mol Biol 2007; 42:67-93. [PMID: 17453916 DOI: 10.1080/10409230701279118] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Proteins of the metallo-beta-lactamase family with either demonstrated or predicted nuclease activity have been identified in a number of organisms ranging from bacteria to humans and has been shown to be important constituents of cellular metabolism. Nucleases of this family are believed to utilize a zinc-dependent mechanism in catalysis and function as 5' to 3' exonucleases and or endonucleases in such processes as 3' end processing of RNA precursors, DNA repair, V(D)J recombination, and telomere maintenance. Examples of metallo-beta-lactamase nucleases include CPSF-73, a known component of the cleavage/polyadenylation machinery, which functions as the endonuclease in 3' end formation of both polyadenylated and histone mRNAs, and Artemis that opens DNA hairpins during V(D)J recombination. Mutations in two metallo-beta-lactamase nucleases have been implicated in human diseases: tRNase Z required for 3' processing of tRNA precursors has been linked to the familial form of prostate cancer, whereas inactivation of Artemis causes severe combined immunodeficiency (SCID). There is also a group of as yet uncharacterized proteins of this family in bacteria and archaea that based on sequence similarity to CPSF-73 are predicted to function as nucleases in RNA metabolism. This article reviews the cellular roles of nucleases of the metallo-beta-lactamase family and the recent advances in studying these proteins.
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Affiliation(s)
- Zbigniew Dominski
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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19
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Dominski Z, Marzluff WF. Formation of the 3' end of histone mRNA: getting closer to the end. Gene 2007; 396:373-90. [PMID: 17531405 PMCID: PMC2888136 DOI: 10.1016/j.gene.2007.04.021] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 04/09/2007] [Indexed: 11/17/2022]
Abstract
Nearly all eukaryotic mRNAs end with a poly(A) tail that is added to their 3' end by the ubiquitous cleavage/polyadenylation machinery. The only known exceptions to this rule are metazoan replication-dependent histone mRNAs, which end with a highly conserved stem-loop structure. This distinct 3' end is generated by specialized 3' end processing machinery that cleaves histone pre-mRNAs 4-5 nucleotides downstream of the stem-loop and consists of the U7 small nuclear RNP (snRNP) and number of protein factors. Recently, the U7 snRNP has been shown to contain a unique Sm core that differs from that of the spliceosomal snRNPs, and an essential heat labile processing factor has been identified as symplekin. In addition, cross-linking studies have pinpointed CPSF-73 as the endonuclease, which catalyzes the cleavage reaction. Thus, many of the critical components of the 3' end processing machinery are now identified. Strikingly, this machinery is not as unique as initially thought but contains at least two factors involved in cleavage/polyadenylation, suggesting that the two mechanisms have a common evolutionary origin. The greatest challenge that lies ahead is to determine how all these factors interact with each other to form a catalytically competent processing complex capable of cleaving histone pre-mRNAs.
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Affiliation(s)
- Zbigniew Dominski
- Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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20
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Jaeger S, Martin F, Rudinger-Thirion J, Giegé R, Eriani G. Binding of human SLBP on the 3'-UTR of histone precursor H4-12 mRNA induces structural rearrangements that enable U7 snRNA anchoring. Nucleic Acids Res 2006; 34:4987-95. [PMID: 16982637 PMCID: PMC1635294 DOI: 10.1093/nar/gkl666] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In metazoans, cell-cycle-dependent histones are produced from poly(A)-lacking mRNAs. The 3′ end of histone mRNAs is formed by an endonucleolytic cleavage of longer precursors between a conserved stem–loop structure and a purine-rich histone downstream element (HDE). The cleavage requires at least two trans-acting factors: the stem–loop binding protein (SLBP), which binds to the stem–loop and the U7 snRNP, which anchors to histone pre-mRNAs by annealing to the HDE. Using RNA structure-probing techniques, we determined the secondary structure of the 3′-untranslated region (3′-UTR) of mouse histone pre-mRNAs H4–12, H1t and H2a–614. Surprisingly, the HDE is embedded in hairpin structures and is therefore not easily accessible for U7 snRNP anchoring. Probing of the 3′-UTR in complex with SLBP revealed structural rearrangements leading to an overall opening of the structure especially at the level of the HDE. Electrophoretic mobility shift assays demonstrated that the SLBP-induced opening of HDE actually facilitates U7 snRNA anchoring on the histone H4–12 pre-mRNAs 3′ end. These results suggest that initial binding of the SLBP functions in making the HDE more accessible for U7 snRNA anchoring.
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Affiliation(s)
| | | | | | | | - Gilbert Eriani
- To whom correspondence should be addressed: Tel: +33 3 88 41 70 42; Fax: +33 3 88 60 22 18;
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21
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Kolev NG, Steitz JA. In vivo assembly of functional U7 snRNP requires RNA backbone flexibility within the Sm-binding site. Nat Struct Mol Biol 2006; 13:347-53. [PMID: 16547514 DOI: 10.1038/nsmb1075] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 02/17/2006] [Indexed: 11/08/2022]
Abstract
Most histone precursor mRNAs (pre-mRNAs) in metazoans are matured by 3'-end cleavage directed by the U7 small nuclear ribonucleoprotein (snRNP). RNA functional groups necessary for in vivo assembly and activity of the U7 snRNP were examined by nucleotide-analog interference mapping and mutagenesis using a chimeric mouse histone H4 pre-mRNA-U7 snRNA construct that is cleaved in cis in Xenopus laevis oocytes. Assembly of the unique U7 Sm protein core is rate limiting for processing in vivo and requires four conserved nucleotides within the U7 Sm-binding site, as well as the correct positioning and size of the U7 terminal stem-loop structure. To our surprise, pseudouridine substitution revealed a requirement for backbone flexibility at a particular position within the U7 Sm site, providing in vivo biochemical evidence that an unusual C2'-endo sugar conformation is necessary for assembly of the Sm ring.
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Affiliation(s)
- Nikolay G Kolev
- Howard Hughes Medical Institute, Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06536, USA
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22
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Dominski Z, Yang XC, Purdy M, Marzluff WF. Differences and similarities between Drosophila and mammalian 3' end processing of histone pre-mRNAs. RNA (NEW YORK, N.Y.) 2005; 11:1835-47. [PMID: 16251385 PMCID: PMC1370872 DOI: 10.1261/rna.2179305] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We used nuclear extracts from Drosophila Kc cells to characterize 3' end processing of Drosophila histone pre-mRNAs. Drosophila SLBP plays a critical role in recruiting the U 7 snRNP to the pre-mRNA and is essential for processing all five Drosophila histone pre-mRNAs. The Drosophila processing machinery strongly prefers cleavage after a fourth nucleotide following the stem-loop and favors an adenosine over pyrimidines in this position. Increasing the distance between the stem-loop and the HDE does not result in a corresponding shift of the cleavage site, suggesting that in Drosophila processing the U 7 snRNP does not function as a molecular ruler. Instead, SLBP directs the cleavage site close to the stem-loop. The upstream cleavage product generated in Drosophila nuclear extracts contains a 3' OH, and the downstream cleavage product is degraded by a nuclease dependent on the U 7 snRNP, suggesting that the cleavage factor has been conserved between Drosophila and mammalian processing. A 2'O-methyl oligonucleotide complementary to the first 17 nt of the Drosophila U 7 snRNA was not able to deplete the U 7 snRNP from Drosophila nuclear extracts, suggesting that the 5' end of the Drosophila U 7 snRNA is inaccessible. This oligonucleotide selectively inhibited processing of only two Drosophila pre-mRNAs and had no effect on processing of the other three pre-mRNAs. Together, these studies demonstrate that although Drosophila and mammalian histone pre-mRNA processing share common features, there are also significant differences, likely reflecting divergence in the mechanism of 3' end processing between vertebrates and invertebrates.
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Affiliation(s)
- Zbigniew Dominski
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA.
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23
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Kolev NG, Steitz JA. Symplekin and multiple other polyadenylation factors participate in 3'-end maturation of histone mRNAs. Genes Dev 2005; 19:2583-92. [PMID: 16230528 PMCID: PMC1276732 DOI: 10.1101/gad.1371105] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Most metazoan messenger RNAs encoding histones are cleaved, but not polyadenylated at their 3' ends. Processing in mammalian cell extracts requires the U7 small nuclear ribonucleoprotein (U7 snRNP) and an unidentified heat-labile factor (HLF). We describe the identification of a heat-sensitive protein complex whose integrity is required for histone pre-mRNA cleavage. It includes all five subunits of the cleavage and polyadenylation specificity factor (CPSF), two subunits of the cleavage stimulation factor (CstF), and symplekin. Reconstitution experiments reveal that symplekin, previously shown to be necessary for cytoplasmic poly(A) tail elongation and translational activation of mRNAs during Xenopus oocyte maturation, is the essential heat-labile component. Thus, a common molecular machinery contributes to the nuclear maturation of mRNAs both lacking and possessing poly(A), as well as to cytoplasmic poly(A) tail elongation.
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Affiliation(s)
- Nikolay G Kolev
- Howard Hughes Medical Institute, Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06536, USA
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24
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Azzouz TN, Gruber A, Schümperli D. U7 snRNP-specific Lsm11 protein: dual binding contacts with the 100 kDa zinc finger processing factor (ZFP100) and a ZFP100-independent function in histone RNA 3' end processing. Nucleic Acids Res 2005; 33:2106-17. [PMID: 15824063 PMCID: PMC1075925 DOI: 10.1093/nar/gki516] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The 3′ cleavage generating non-polyadenylated animal histone mRNAs depends on the base pairing between U7 snRNA and a conserved histone pre-mRNA downstream element. This interaction is enhanced by a 100 kDa zinc finger protein (ZFP100) that forms a bridge between an RNA hairpin element upstream of the processing site and the U7 small nuclear ribonucleoprotein (snRNP). The N-terminus of Lsm11, a U7-specific Sm-like protein, was shown to be crucial for histone RNA processing and to bind ZFP100. By further analysing these two functions of Lsm11, we find that Lsm11 and ZFP100 can undergo two interactions, i.e. between the Lsm11 N-terminus and the zinc finger repeats of ZFP100, and between the N-terminus of ZFP100 and the Sm domain of Lsm11, respectively. Both interactions are not specific for the two proteins in vitro, but the second interaction is sufficient for a specific recognition of the U7 snRNP by ZFP100 in cell extracts. Furthermore, clustered point mutations in three phylogenetically conserved regions of the Lsm11 N-terminus impair or abolish histone RNA processing. As these mutations have no effect on the two interactions with ZFP100, these protein regions must play other roles in histone RNA processing, e.g. by contacting the pre-mRNA or additional processing factors.
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Affiliation(s)
| | | | - Daniel Schümperli
- To whom correspondence should be addressed. Tel: +41 31 631 4675; Fax: +41 31 631 4616;
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25
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Azzouz TN, Schumperli D. Evolutionary conservation of the U7 small nuclear ribonucleoprotein in Drosophila melanogaster. RNA (NEW YORK, N.Y.) 2003; 9:1532-41. [PMID: 14624008 PMCID: PMC1370506 DOI: 10.1261/rna.5143303] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Accepted: 09/04/2003] [Indexed: 05/21/2023]
Abstract
The U7 snRNP involved in histone RNA 3' end processing is related to but biochemically distinct from spliceosomal snRNPs. In vertebrates, the Sm core structure assembling around the noncanonical Sm-binding sequence of U7 snRNA contains only five of the seven standard Sm proteins. The missing Sm D1 and D2 subunits are replaced by U7-specific Sm-like proteins Lsm10 and Lsm11, at least the latter of which is important for histone RNA processing. So far, it was unknown if this special U7 snRNP composition is conserved in invertebrates. Here we describe several putative invertebrate Lsm10 and Lsm11 orthologs that display low but clear sequence similarity to their vertebrate counterparts. Immunoprecipitation studies in Drosophila S2 cells indicate that the Drosophila Lsm10 and Lsm11 orthologs (dLsm10 and dLsm11) associate with each other and with Sm B, but not with Sm D1 and D2. Moreover, dLsm11 associates with the recently characterized Drosophila U7 snRNA and, indirectly, with histone H3 pre-mRNA. Furthermore, dLsm10 and dLsm11 can assemble into U7 snRNPs in mammalian cells. These experiments demonstrate a strong evolutionary conservation of the unique U7 snRNP composition, despite a high degree of primary sequence divergence of its constituents. Therefore, Drosophila appears to be a suitable system for further genetic studies of the cell biology of U7 snRNPs.
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Affiliation(s)
- Teldja N Azzouz
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
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26
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Pillai RS, Grimmler M, Meister G, Will CL, Lührmann R, Fischer U, Schümperli D. Unique Sm core structure of U7 snRNPs: assembly by a specialized SMN complex and the role of a new component, Lsm11, in histone RNA processing. Genes Dev 2003; 17:2321-33. [PMID: 12975319 PMCID: PMC196468 DOI: 10.1101/gad.274403] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A set of seven Sm proteins assemble on the Sm-binding site of spliceosomal U snRNAs to form the ring-shaped Sm core. The U7 snRNP involved in histone RNA 3' processing contains a structurally similar but biochemically unique Sm core in which two of these proteins, Sm D1 and D2, are replaced by Lsm10 and by another as yet unknown component. Here we characterize this factor, termed Lsm11, as a novel Sm-like protein with apparently two distinct functions. In vitro studies suggest that its long N-terminal part mediates an important step in histone mRNA 3'-end cleavage, most likely by recruiting a zinc finger protein previously identified as a processing factor. In contrast, the C-terminal part, which comprises two Sm motifs interrupted by an unusually long spacer, is sufficient to assemble with U7, but not U1, snRNA. Assembly of this U7-specific Sm core depends on the noncanonical Sm-binding site of U7 snRNA. Moreover, it is facilitated by a specialized SMN complex that contains Lsm10 and Lsm11 but lacks Sm D1/D2. Thus, the U7-specific Lsm11 protein not only specifies the assembly of the U7 Sm core but also fulfills an important role in U7 snRNP-mediated histone mRNA processing.
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Affiliation(s)
- Ramesh S Pillai
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
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27
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Adamson TE, Price DH. Cotranscriptional processing of Drosophila histone mRNAs. Mol Cell Biol 2003; 23:4046-55. [PMID: 12773550 PMCID: PMC156150 DOI: 10.1128/mcb.23.12.4046-4055.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2002] [Revised: 02/06/2003] [Accepted: 03/21/2003] [Indexed: 11/20/2022] Open
Abstract
The 3' ends of metazoan histone mRNAs are generated by specialized processing machinery that cleaves downstream of a conserved stem-loop structure. To examine how this reaction might be influenced by transcription, we used a Drosophila melanogaster in vitro system that supports both processes. In this system the complete synthesis of histone mRNA, including transcription initiation and elongation, followed by 3' end formation, occurred at a physiologically significant rate. Processing of free transcripts was efficient and occurred with a t(1/2) of less than 1 min. Divalent cations were not required, but nucleoside triphosphates (NTPs) stimulated the rate of cleavage slightly. Isolated elongation complexes encountered a strong arrest site downstream of the mature histone H4 3' end. In the presence of NTPs, transcripts in these arrested complexes were processed at a rate similar to that of free RNA. Removal of NTPs dramatically reduced this rate, potentially due to concealment of the U7 snRNP binding element. The arrest site was found to be a conserved feature located 32 to 35 nucleotides downstream of the processing site on the H4, H2b, and H3 genes. The significance of the newly discovered arrest sites to our understanding of the coupling between transcription and RNA processing on the one hand and histone gene expression on the other is discussed.
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Affiliation(s)
- Todd E Adamson
- Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
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28
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Dominski Z, Yang XC, Raska CS, Santiago C, Borchers CH, Duronio RJ, Marzluff WF. 3' end processing of Drosophila melanogaster histone pre-mRNAs: requirement for phosphorylated Drosophila stem-loop binding protein and coevolution of the histone pre-mRNA processing system. Mol Cell Biol 2002; 22:6648-60. [PMID: 12192062 PMCID: PMC135633 DOI: 10.1128/mcb.22.18.6648-6660.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synthetic pre-mRNAs containing the processing signals encoded by Drosophila melanogaster histone genes undergo efficient and faithful endonucleolytic cleavage in nuclear extracts prepared from Drosophila cultured cells and 0- to 13-h-old embryos. Biochemical requirements for the in vitro cleavage are similar to those previously described for the 3' end processing of mammalian histone pre-mRNAs. Drosophila 3' end processing does not require ATP and occurs in the presence of EDTA. However, in contrast to mammalian processing, Drosophila processing generates the final product ending four nucleotides after the stem-loop. Cleavage of the Drosophila substrates is abolished by depleting the extract of the Drosophila stem-loop binding protein (dSLBP), indicating that both dSLBP and the stem-loop structure in histone pre-mRNA are essential components of the processing machinery. Recombinant dSLBP expressed in insect cells by using the baculovirus system efficiently complements the depleted extract. Only the RNA-binding domain plus the 17 amino acids at the C terminus of dSLBP are required for processing. The full-length dSLBP expressed in insect cells is quantitatively phosphorylated on four residues in the C-terminal region. Dephosphorylation of the recombinant dSLBP reduces processing activity. Human and Drosophila SLBPs are not interchangeable and strongly inhibit processing in the heterologous extracts. The RNA-binding domain of the dSLBP does not substitute for the RNA-binding domain of the human SLBP in histone pre-mRNA processing in mammalian extracts. In addition to the stem-loop structure and dSLBP, 3' processing in Drosophila nuclear extracts depends on the presence of a short stretch of purines located ca. 20 nucleotides downstream from the stem, and an Sm-reactive factor, most likely the Drosophila counterpart of vertebrate U7 snRNP.
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Affiliation(s)
- Zbigniew Dominski
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, 27599, USA
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29
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Zanier K, Luyten I, Crombie C, Muller B, Schümperli D, Linge JP, Nilges M, Sattler M. Structure of the histone mRNA hairpin required for cell cycle regulation of histone gene expression. RNA (NEW YORK, N.Y.) 2002; 8:29-46. [PMID: 11871659 PMCID: PMC1370228 DOI: 10.1017/s1355838202014061] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Expression of replication-dependent histone genes requires a conserved hairpin RNA element in the 3' untranslated regions of poly(A)-less histone mRNAs. The 3' hairpin element is recognized by the hairpin-binding protein or stem-loop-binding protein (HBP/SLBP). This protein-RNA interaction is important for the endonucleolytic cleavage generating the mature mRNA 3' end. The 3' hairpin and presumably HBP/SLBP are also required for nucleocytoplasmic transport, translation, and stability of histone mRNAs. RNA 3' processing and mRNA stability are both regulated during the cell cycle. Here, we have determined the three-dimensional structure of a 24-mer RNA comprising a mammalian histone RNA hairpin using heteronuclear multidimensional NMR spectroscopy. The hairpin adopts a novel UUUC tetraloop conformation that is stabilized by base stacking involving the first and third loop uridines and a closing U-A base pair, and by hydrogen bonding between the first and third uridines in the tetraloop. The HBP interaction of hairpin RNA variants was analyzed in band shift experiments. Particularly important interactions for HBP recognition are mediated by the closing U-A base pair and the first and third loop uridines, whose Watson-Crick functional groups are exposed towards the major groove of the RNA hairpin. The results obtained provide novel structural insight into the interaction of the histone 3' hairpin with HBP, and thus the regulation of histone mRNA metabolism.
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Affiliation(s)
- Katia Zanier
- European Molecular Biology Laboratory, Heidelberg, Germany
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30
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Kodama Y, Rothman JH, Sugimoto A, Yamamoto M. The stem-loop binding protein CDL-1 is required for chromosome condensation, progression of cell death and morphogenesis inCaenorhabditis elegans. Development 2002; 129:187-96. [PMID: 11782412 DOI: 10.1242/dev.129.1.187] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Histones play important roles not only in the structural changes of chromatin but also in regulating gene expression. Expression of histones is partly regulated post-transcriptionally by the stem-loop binding protein (SLBP)/hairpin binding protein (HBP). We report the developmental function of CDL-1, the C. elegans homologue of SLBP/HBP. In the C. elegans cdl-1 mutants, cell corpses resulting from programmed cell death appear later and persist much longer than those in the wild type. They also exhibit distinct morphological defects in body elongation and movement of the pharyngeal cells toward the buccal opening. The CDL-1 protein binds to the stem-loop structures in the 3′-UTR of C. elegans core histone mRNAs, and the mutant forms of this protein show reduced binding activities. A decrease in the amount of core histone proteins phenocopied the cdl-1 mutant embryos, suggesting that CDL-1 contributes to the proper expression of core histone proteins. We propose that loss-of-function of cdl-1 causes aberrant chromatin structure, which affects the cell cycle and cell death, as well as transcription of genes essential for morphogenesis.
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Affiliation(s)
- Yuki Kodama
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Bunkyo, 113-0032, Japan
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31
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Dominski Z, Erkmann JA, Yang X, Sànchez R, Marzluff WF. A novel zinc finger protein is associated with U7 snRNP and interacts with the stem-loop binding protein in the histone pre-mRNP to stimulate 3'-end processing. Genes Dev 2002; 16:58-71. [PMID: 11782445 PMCID: PMC155312 DOI: 10.1101/gad.932302] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The stem-loop binding protein (SLBP) is the posttranscriptional regulator of histone mRNA in metazoan cells. SLBP binds histone pre-mRNAs and facilitates 3'-end processing by promoting stable association of U7 snRNP with the pre-mRNA. To identify other factors involved in histone pre-mRNA processing, we used a modified yeast two-hybrid assay in which SLBP and its RNA target were coexpressed as bait. A novel zinc finger protein, hZFP100, which interacts with the SLBP/RNA complex but not with free SLBP, was cloned. The interaction requires regions of SLBP that are important for histone pre-mRNA processing. Antibodies to hZFP100 precipitate U7 snRNA, and expression of hZFP100 in Xenopus oocytes stimulates processing of histone pre-mRNA, showing that hZFP100 is a component of the processing machinery.
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Affiliation(s)
- Zbigniew Dominski
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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32
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Dominski Z, Erkmann JA, Greenland JA, Marzluff WF. Mutations in the RNA binding domain of stem-loop binding protein define separable requirements for RNA binding and for histone pre-mRNA processing. Mol Cell Biol 2001; 21:2008-17. [PMID: 11238936 PMCID: PMC86798 DOI: 10.1128/mcb.21.6.2008-2017.2001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Expression of replication-dependent histone genes at the posttranscriptional level is controlled by stem-loop binding protein (SLBP). One function of SLBP is to bind the stem-loop structure in the 3' untranslated region of histone pre-mRNAs and facilitate 3' end processing. Interaction of SLBP with the stem-loop is mediated by the centrally located RNA binding domain (RBD). Here we identify several highly conserved amino acids in the RBD mutation of which results in complete or substantial loss of SLBP binding activity. We also identify residues in the RBD which do not contribute to binding to the stem-loop RNA but instead are required for efficient recruitment of U7 snRNP to histone pre-mRNA. Recruitment of the U7 snRNP to the pre-mRNA also depends on the 20-amino-acid region located immediately downstream of the RBD. A critical region of the RBD contains the sequence YDRY. The tyrosines are required for RNA binding, and the DR dipeptide is essential for processing but not for RNA binding. It is likely that the RBD of SLBP interacts directly with both the stem-loop RNA and other processing factor(s), most likely the U7 snRNP, to facilitate histone pre-mRNA processing.
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Affiliation(s)
- Z Dominski
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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33
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Battle DJ, Doudna JA. The stem-loop binding protein forms a highly stable and specific complex with the 3' stem-loop of histone mRNAs. RNA (NEW YORK, N.Y.) 2001; 7:123-32. [PMID: 11214174 PMCID: PMC1370062 DOI: 10.1017/s1355838201001820] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Replication-dependent histone mRNAs end in a highly conserved 26-nt stem-loop structure. The stem-loop binding protein (SLBP), an evolutionarily conserved protein with no known homologs, interacts with the stem-loop in both the nucleus and cytoplasm and mediates nuclear-cytoplasmic transport as well as 3'-end processing of the pre-mRNA by the U7 snRNP. Here, we examined the affinity and specificity of the SLBP-RNA interaction. Nitrocellulose filter-binding experiments showed that the apparent equilibrium dissociation constant (Kd) between purified SLBP and the stem-loop RNA is 1.5 nM. Binding studies with a series of stem-loop variants demonstrated that conserved residues in the stem and loop, as well as the 5' and 3' flanking regions, are required for efficient protein recognition. Deletion analysis showed that 3 nt 5' of the stem and 1 nt 3' of the stem contribute to the binding energy. These data reveal that the high affinity complex between SLBP and the RNA involves sequence-specific contacts to the loop and the top of the stem, as well the base of the stem and its immediate flanking sequences. Together, these results suggest a novel mode of protein-RNA recognition that forms the core of a ribonucleoprotein complex central to the regulation of histone gene expression.
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Affiliation(s)
- D J Battle
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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34
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Ingledue TC, Dominski Z, Sánchez R, Erkmann JA, Marzluff WF. Dual role for the RNA-binding domain of Xenopus laevis SLBP1 in histone pre-mRNA processing. RNA (NEW YORK, N.Y.) 2000; 6:1635-48. [PMID: 11105762 PMCID: PMC1370032 DOI: 10.1017/s1355838200000819] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The replication-dependent histone mRNAs end in a conserved 26-nt sequence that forms a stem-loop structure. This sequence is required for histone pre-mRNA processing and plays a role in multiple aspects of histone mRNA metabolism. Two proteins that bind the 3' end of histone mRNA are found in Xenopus oocytes. xSLBP1 is found in the nucleus, where it functions in histone pre-mRNA processing, and in the cytoplasm, where it may control histone mRNA translation and stability. xSLBP2 is a cytoplasmic protein, inactive in histone pre-mRNA processing, whose expression is restricted to oogenesis and early development. These proteins are similar only in their RNA-binding domains (RBD). A chimeric protein (1-2-1) in which the RBD of xSLBP1 has been replaced with the RBD of xSLBP2 binds the stem-loop with an affinity similar to the original protein. The 1-2-1 protein efficiently localizes to the nucleus of the frog oocyte, but is not active in processing of histone pre-mRNA in vivo. This protein does not support processing in a nuclear extract, but inhibits processing by competing with the active SLBP by binding to the substrate. The 1-2-1 protein also inhibits processing of synthetic histone pre-mRNA injected into frog oocytes, but has no effect on processing of histone pre-mRNA transcribed from an injected histone gene. This result suggests that sequences in the RBD of xSLBP1 give it preferential access to histone pre-mRNA transcribed in vivo.
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Affiliation(s)
- T C Ingledue
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599, USA
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35
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Müller B, Link J, Smythe C. Assembly of U7 small nuclear ribonucleoprotein particle and histone RNA 3' processing in Xenopus egg extracts. J Biol Chem 2000; 275:24284-93. [PMID: 10827192 DOI: 10.1074/jbc.m003253200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In animals, replication-dependent histone genes are expressed in dividing somatic cells during S phase to maintain chromatin condensation. Histone mRNA 3'-end formation is an essential regulatory step producing an mRNA with a hairpin structure at the 3'-end. This requires the interaction of the U7 small nuclear ribonucleoprotein particle (snRNP) with a purine-rich spacer element and of the hairpin-binding protein with the hairpin element, respectively, in the 3'-untranslated region of histone RNA. Here, we demonstrate that bona fide histone RNA 3' processing takes place in Xenopus egg extracts in a reaction dependent on the addition of synthetic U7 RNA that is assembled into a ribonucleoprotein particle by protein components available in the extract. In addition to reconstituted U7 snRNP, Xenopus hairpin-binding protein SLBP1 is necessary for efficient processing. Histone RNA 3' processing is not affected by addition of non-destructible cyclin B, which drives the egg extract into M phase, but SLBP1 is phosphorylated in this extract. SPH-1, the Xenopus homologue of human p80-coilin found in coiled bodies, is associated with U7 snRNPs. However, this does not depend on the U7 RNA being able to process histone RNA and also occurs with U1 snRNPs; therefore, association of SPH1 cannot be considered as a hallmark of a functional U7 snRNP.
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Affiliation(s)
- B Müller
- Abteilung Entwicklungsbiologie, Zoologisches Institut, Universität Bern, Baltzerstrasse 4, CH 3012 Bern, Switzerland.
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36
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Abstract
All metazoan messenger RNAs, with the exception of the replication-dependent histone mRNAs, terminate at the 3' end with a poly(A) tail. Replication-dependent histone mRNAs end instead in a conserved 26-nucleotide sequence that contains a 16-nucleotide stem-loop. Formation of the 3' end of histone mRNA occurs by endonucleolytic cleavage of pre-mRNA releasing the mature mRNA from the chromatin template. Cleavage requires several trans-acting factors, including a protein, the stem-loop binding protein (SLBP), which binds the 26-nucleotide sequence; and a small nuclear RNP, U7 snRNP. There are probably additional factors also required for cleavage. One of the functions of the SLBP is to stabilize binding of the U7 snRNP to the histone pre-mRNA. In the nucleus, both U7 snRNP and SLBP are present in coiled bodies, structures that are associated with histone genes and may play a direct role in histone pre-mRNA processing in vivo. One of the major regulatory events in the cell cycle is regulation of histone pre-mRNA processing, which is at least partially mediated by cell-cycle regulation of the levels of the SLBP protein.
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Affiliation(s)
- Z Dominski
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599, USA
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37
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García-Salcedo JA, Gijón P, Pays E. Regulated transcription of the histone H2B genes of Trypanosoma brucei. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:717-23. [PMID: 10491117 DOI: 10.1046/j.1432-1327.1999.00592.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Trypanosoma brucei, the genes encoding histone H2B are organized in a cluster of about 10-15 tandemly linked copies per haploid genome. The H2B transcripts are processed by trans-splicing and polyadenylation, and encode a polypeptide of 111 residues with a molecular mass of 12.5 kDa. H2B mRNAs are differentially expressed during the parasite life-cycle and are present at higher levels in dividing procyclic and bloodstream slender forms than in the nondividing bloodstream stumpy forms. Analysis of H2B mRNA levels during the synchronous differentiation from stumpy to procyclics forms revealed that the abundance of these transcripts is regulated through the cell-cycle, reaching maximum levels during S-phase. Addition of hydroxyurea to procyclic forms in culture specifically decreased H2B mRNA levels by about twofold, an effect not linked to its 3' untranslated region. Inhibition of protein synthesis prevented this decrease.
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Affiliation(s)
- J A García-Salcedo
- Laboratory of Molecular Parasitology, Department of Molecular Biology, Free University of Brussels, Belgium.
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38
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Zhao J, Hyman L, Moore C. Formation of mRNA 3' ends in eukaryotes: mechanism, regulation, and interrelationships with other steps in mRNA synthesis. Microbiol Mol Biol Rev 1999; 63:405-45. [PMID: 10357856 PMCID: PMC98971 DOI: 10.1128/mmbr.63.2.405-445.1999] [Citation(s) in RCA: 808] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Formation of mRNA 3' ends in eukaryotes requires the interaction of transacting factors with cis-acting signal elements on the RNA precursor by two distinct mechanisms, one for the cleavage of most replication-dependent histone transcripts and the other for cleavage and polyadenylation of the majority of eukaryotic mRNAs. Most of the basic factors have now been identified, as well as some of the key protein-protein and RNA-protein interactions. This processing can be regulated by changing the levels or activity of basic factors or by using activators and repressors, many of which are components of the splicing machinery. These regulatory mechanisms act during differentiation, progression through the cell cycle, or viral infections. Recent findings suggest that the association of cleavage/polyadenylation factors with the transcriptional complex via the carboxyl-terminal domain of the RNA polymerase II (Pol II) large subunit is the means by which the cell restricts polyadenylation to Pol II transcripts. The processing of 3' ends is also important for transcription termination downstream of cleavage sites and for assembly of an export-competent mRNA. The progress of the last few years points to a remarkable coordination and cooperativity in the steps leading to the appearance of translatable mRNA in the cytoplasm.
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Affiliation(s)
- J Zhao
- Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, Massachusetts 02111, USA
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39
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Zhao J, Hyman L, Moore C. Formation of mRNA 3' ends in eukaryotes: mechanism, regulation, and interrelationships with other steps in mRNA synthesis. Microbiol Mol Biol Rev 1999. [PMID: 10357856 DOI: 10.1007/s13146-011-0050-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
Formation of mRNA 3' ends in eukaryotes requires the interaction of transacting factors with cis-acting signal elements on the RNA precursor by two distinct mechanisms, one for the cleavage of most replication-dependent histone transcripts and the other for cleavage and polyadenylation of the majority of eukaryotic mRNAs. Most of the basic factors have now been identified, as well as some of the key protein-protein and RNA-protein interactions. This processing can be regulated by changing the levels or activity of basic factors or by using activators and repressors, many of which are components of the splicing machinery. These regulatory mechanisms act during differentiation, progression through the cell cycle, or viral infections. Recent findings suggest that the association of cleavage/polyadenylation factors with the transcriptional complex via the carboxyl-terminal domain of the RNA polymerase II (Pol II) large subunit is the means by which the cell restricts polyadenylation to Pol II transcripts. The processing of 3' ends is also important for transcription termination downstream of cleavage sites and for assembly of an export-competent mRNA. The progress of the last few years points to a remarkable coordination and cooperativity in the steps leading to the appearance of translatable mRNA in the cytoplasm.
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Affiliation(s)
- J Zhao
- Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, Massachusetts 02111, USA
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40
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Dominski Z, Zheng LX, Sanchez R, Marzluff WF. Stem-loop binding protein facilitates 3'-end formation by stabilizing U7 snRNP binding to histone pre-mRNA. Mol Cell Biol 1999; 19:3561-70. [PMID: 10207079 PMCID: PMC84148 DOI: 10.1128/mcb.19.5.3561] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 3' end of histone mRNA is formed by an endonucleolytic cleavage of the primary transcript after a conserved stem-loop sequence. The cleavage reaction requires at least two trans-acting factors: the stem-loop binding protein (SLBP), which binds the stem-loop sequence, and the U7 snRNP that interacts with a sequence downstream from the cleavage site. Removal of SLBP from a nuclear extract abolishes 3'-end processing, and the addition of recombinant SLBP restores processing activity of the depleted extract. To determine the regions of human SLBP necessary for 3' processing, various deletion mutants of the protein were tested for their ability to complement the SLBP-depleted extract. The entire N-terminal domain and the majority of the C-terminal domain of human SLBP are dispensable for processing. The minimal protein that efficiently supports cleavage of histone pre-mRNA consists of 93 amino acids containing the 73-amino-acid RNA-binding domain and 20 amino acids located immediately next to its C terminus. Replacement of these 20 residues with an unrelated sequence in the context of the full-length SLBP reduces processing >90%. Coimmunoprecipitation experiments with the anti-SLBP antibody demonstrated that SLBP and U7 snRNP form a stable complex only in the presence of pre-mRNA substrates containing a properly positioned U7 snRNP binding site. One role of SLBP is to stabilize the interaction of the histone pre-mRNA with U7 snRNP.
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Affiliation(s)
- Z Dominski
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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41
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Walther TN, Wittop Koning TH, Schümperli D, Müller B. A 5'-3' exonuclease activity involved in forming the 3' products of histone pre-mRNA processing in vitro. RNA (NEW YORK, N.Y.) 1998; 4:1034-46. [PMID: 9740123 PMCID: PMC1369680 DOI: 10.1017/s1355838298971771] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Histone RNA 3' processing in vitro produces one or more 5' cleavage products corresponding to the mature histone mRNA 3' end, and a group of 3' cleavage products whose 5' ends are mostly located several nucleotides downstream of the mRNA 3' end. The formation of these 3' products is coupled to the formation of 5' products and dependent on the U7 snRNP and a heat-labile processing factor. These short 3' products therefore are a true and general feature of the processing reaction. Identical 3' products are also formed from a model RNA containing all spacer nucleotides downstream of the mature mRNA 3' end, but no sequences from the mature mRNA. Again, this reaction is dependent on both the U7 snRNP and a heat-labile factor. Unlike the processing with a full-length histone pre-mRNA, this reaction produces only 3' but no 5' fragments. In addition, product formation is inhibited by addition of cap structures at the model RNA 5' end, indicating that product formation occurs by 5'-3' exonucleolytic degradation. This degradation of a model 3' product by a 5'-3' exonuclease suggests a mechanism for the release of the U7 snRNP after processing by shortening the cut-off histone spacer sequences base paired to U7 RNA.
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Affiliation(s)
- T N Walther
- Abteilung für Entwicklungsbiologie, Zoologisches Institut, Universität Bern, Switzerland
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42
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Furger A, Schaller A, Schümperli D. Functional importance of conserved nucleotides at the histone RNA 3' processing site. RNA (NEW YORK, N.Y.) 1998; 4:246-256. [PMID: 9510327 PMCID: PMC1369614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Histone pre-mRNA 3' processing is controlled by a hairpin element preceding the processing site that interacts with a hairpin-binding protein (HBP) and a downstream spacer element that serves as anchoring site for the U7 snRNP. In addition, the nucleotides following the hairpin and surrounding the processing site (ACCCA'CA) are conserved among vertebrate histone genes. Single to triple nucleotide mutations of this sequence were tested for their ability to be processed in nuclear extract from animal cells. Changing the first four nucleotides had no qualitative and little if any quantitative effects on histone RNA 3' processing in mouse K21 cell extract, where processing of this gene is virtually independent of the HBP. A gel mobility shift assay revealing HBP interactions and a processing assay in HeLa cell extract (where the contribution of HBP to efficient processing is more important) showed that only one of these mutations, predicted to extend the hairpin by one base pair, affected the interaction with HBP. Mutations in the next three nucleotides affected both the cleavage efficiency and the choice of processing sites. Analysis of these novel sites indicated a preference for the nucleotide 5' of the cleavage site in the order A > C > U > G. Moreover, a guanosine in the 3' position inhibited cleavage. The preference for an A is shared with the cleavage/polyadenylation reaction, but the preference order for the other nucleotides is different [Chen F, MacDonald CC, Wilusz J, 1995, Nucleic Acids Res 23:2614-2620].
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Affiliation(s)
- A Furger
- Abteilung für Entwicklungsbiologie, Zoologisches Institut der Universität Bern, Switzerland
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43
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Schaller A, Martin F, Müller B. Characterization of the calf thymus hairpin-binding factor involved in histone pre-mRNA 3' end processing. J Biol Chem 1997; 272:10435-41. [PMID: 9099685 DOI: 10.1074/jbc.272.16.10435] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Using ion exchange chromatography we have enriched the RNA hairpin-binding factor involved in histone pre-mRNA processing from calf thymus whole cell extract. We demonstrate that the interaction of the factor with its target RNA sequence, the hairpin structure located at the 3' end of mature histone mRNA, is sequence-specific and highly salt-resistant. We have developed a simple in vitro system which allows detection of activities stimulating histone pre-mRNA 3' end processing, based on mouse cell nuclear extract fractionated by Mono Q column chromatography. Using this system, we show that the bovine hairpin-binding factor participates in histone pre-mRNA 3' end processing in vitro. We have further purified the hairpin-binding factor in form of a RNA.protein complex by RNA-mediated elution from phosphocellulose. This led to a fraction highly enriched for 2 proteins of 40 and 43 kDa.
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Affiliation(s)
- A Schaller
- Abteilung Entwicklungsbiologie, Zoologisches Institut, Universität Bern, Baltzerstrasse 4, CH 3012 Bern, Switzerland
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44
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Martin F, Schaller A, Eglite S, Schümperli D, Müller B. The gene for histone RNA hairpin binding protein is located on human chromosome 4 and encodes a novel type of RNA binding protein. EMBO J 1997; 16:769-78. [PMID: 9049306 PMCID: PMC1169678 DOI: 10.1093/emboj/16.4.769] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The hairpin structure at the 3' end of animal histone mRNAs controls histone RNA 3' processing, nucleocytoplasmic transport, translation and stability of histone mRNA. Functionally overlapping, if not identical, proteins binding to the histone RNA hairpin have been identified in nuclear and polysomal extracts. Our own results indicated that these hairpin binding proteins (HBPs) bind their target RNA as monomers and that the resulting ribonucleoprotein complexes are extremely stable. These features prompted us to select for HBP-encoding human cDNAs by RNA-mediated three-hybrid selection in Saccharomyces cerevesiae. Whole cell extract from one selected clone contained a Gal4 fusion protein that interacted with histone hairpin RNA in a sequence- and structure-specific manner similar to a fraction enriched for bovine HBP, indicating that the cDNA encoded HBP. DNA sequence analysis revealed that the coding sequence did not contain any known RNA binding motifs. The HBP gene is composed of eight exons covering 19.5 kb on the short arm of chromosome 4. Translation of the HBP open reading frame in vitro produced a 43 kDa protein with RNA binding specificity identical to murine or bovine HBP. In addition, recombinant HBP expressed in S. cerevisiae was functional in histone pre-mRNA processing, confirming that we have indeed identified the human HBP gene.
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Affiliation(s)
- F Martin
- Abteilung für Entwicklungsbiologie, Zoologisches Institut der Universität Bern, Switzerland
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45
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Wang ZF, Whitfield ML, Ingledue TC, Dominski Z, Marzluff WF. The protein that binds the 3' end of histone mRNA: a novel RNA-binding protein required for histone pre-mRNA processing. Genes Dev 1996; 10:3028-40. [PMID: 8957003 DOI: 10.1101/gad.10.23.3028] [Citation(s) in RCA: 220] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Replication-dependent histone mRNAs are not polyadenylated but end in a conserved 26-nucleotide structure that contains a stem-loop. Much of the cell cycle regulation of histone mRNA is post-transcriptional and is mediated by the 3' end of histone mRNA. The stem-loop binding protein (SLBP) that binds the 3' end of histone mRNA is a candidate for the factor that participates in most, if not all, of the post-transcriptional regulatory events. We have cloned the cDNA for the SLBP from humans, mice, and frogs, using the recently developed yeast three-hybrid system. The human SLBP is a 31-kD protein and contains a novel RNA-binding domain, which has been mapped to a 73-amino-acid region of the protein. The cloned SLBP is the protein bound to the 3' end of histone mRNA as antibodies specific for the SLBP remove all specific binding activity from nuclear and polyribosomal extracts. These depleted extracts do not cleave histone pre-mRNA efficiently, demonstrating that the SLBP is required for efficient histone pre-mRNA processing.
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Affiliation(s)
- Z F Wang
- Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill 27599, USA
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Gallie DR, Lewis NJ, Marzluff WF. The histone 3'-terminal stem-loop is necessary for translation in Chinese hamster ovary cells. Nucleic Acids Res 1996; 24:1954-62. [PMID: 8657580 PMCID: PMC145863 DOI: 10.1093/nar/24.10.1954] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The metazoan cell cycle-regulated histone mRNAs are the only known cellular mRNAs that do not terminate in a poly(A) tall. Instead, mammalian histone mRNAs terminate in a highly conserved stem-loop structure which is required for 3'-end processing and regulates mRNA stability. The poly(A) tail not only regulates translational efficiency and mRNA stability but is required for the function of the cap in translation (m(7)GpppN). We show that the histone terminal stem-loop is functionally similar to a poly(A) tail in that it enhances translational efficiency and is co-dependent on a cap in order to establish an efficient level of translation. The histone stem-loop is sufficient and necessary to increase the translation of reporter mRNA in transfected Chinese hamster ovary cells but must be positioned at the 3'-terminus in order to function optimally. Mutations within the conserved stem or loop regions reduced its ability to facilitate translation. All histone mRNAs in higher plants are polyadenylated. The histone stem-loop did not function to influence translational efficiency or mRNA stability in plant protoplasts. These data demonstrate that the histone stem/loop directs efficient translation and that it is functionally analogous to a poly(A) tail.
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Affiliation(s)
- D R Gallie
- Department of Biochemistry, University of California, Riverside, CA 92521-0129, USA
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Fabry S, Müller K, Lindauer A, Park PB, Cornelius T, Schmitt R. The organization structure and regulatory elements of Chlamydomonas histone genes reveal features linking plant and animal genes. Curr Genet 1995; 28:333-45. [PMID: 8590479 DOI: 10.1007/bf00326431] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The genome of the green alga Chlamydomonas reinhardtii contains approximately 15 gene clusters of the nucleosomal (or core) histone H2A, H2B, H3 and H4 genes and at least one histone H1 gene. Seven non-allelic histone gene loci were isolated from a genomic library, physically mapped, and the nucleotide sequences of three isotypes of each core histone gene species and one linked H1 gene determined. The core histone genes are organized in clusters of H2A-H2B and H3-H4 pairs, in which each gene pair shows outwardly divergent transcription from a short (< 300 bp) intercistronic region. These intercistronic regions contain typically conserved promoter elements, namely a TATA-box and the three motifs TGGCCAG-G(G/C)-CGAG, CGTTGACC and CGGTTG. Different from the genes of higher plants, but like those of animals and the related alga Volvox, the 3' untranslated regions contain no poly A signal, but a palindromic sequence (3' palindrome) essential for mRNA processing is present. One single H1 gene was found in close linkage to a H2A-H2B pair. The H1 upstream region contains the octameric promoter element GGTTGACC (also found upstream of the core histone genes) and two specific sequence motifs that are shared only with the Volvox H1 promoters. This suggests differential transcription of the H1 and the core histone genes. The H1 gene is interrupted by two introns. Unlike Volvox H3 genes, the three sequenced H3 isoforms are intron-free. Primer-directed PCR of genomic DNA demonstrated, however, that at least 8 of the about 15 H3 genes do contain one intron at a conserved position. In synchronized C. reinhardtii cells, H4 mRNA levels (representative of all core histone mRNAs) peak during cell division, suggesting strict replication-dependent gene control. The derived peptide sequences place C. reinhardtii core histones closer to plants than to animals, except that the H2A histones are more animal-like. The peptide sequence of histone H1 is closely related to the V. carteri VH1-II (66% identity). Organization of the core histone gene in pairs, and non-polyadenylation of mRNAs are features shared with animals, whereas peptide sequences and enhancer elements are shared with higher plants, assigning the volvocalean histone genes a position intermediate between animals and plants.
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Affiliation(s)
- S Fabry
- Lehrstuhl, für Genetik, Universität Regensburg, Germany
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Stefanovic B, Hackl W, Lührmann R, Schümperli D. Assembly, nuclear import and function of U7 snRNPs studied by microinjection of synthetic U7 RNA into Xenopus oocytes. Nucleic Acids Res 1995; 23:3141-51. [PMID: 7667090 PMCID: PMC307171 DOI: 10.1093/nar/23.16.3141] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In Xenopus oocytes in vitro transcribed mouse U7 RNA is assembled into small nuclear ribonucleoproteins (snRNPs) that are functional in histone RNA 3' processing. If the special Sm binding site of U7 (AAUUUGUCUAG, U7 Sm WT) is converted into the canonical Sm sequence derived from the major snRNAs (AAUUUUUGGAG, U7 Sm OPT) the RNA assembles into a particle which accumulates more efficiently in the nucleus, but which is non-functional. U7 RNA with a heavily mutated Sm binding site (AACGCGUCAUG, U7 Sm MUT) is deficient in nuclear accumulation and function. By UV cross-linking U7 Sm WT RNA can be linked to three proteins, i.e. the common snRNP proteins G and B/B' and an apparently U7-specific protein of 40 kDa. As a result of altering the Sm binding site, U7 Sm OPT RNA cannot be cross-linked to the 40 kDa protein and no cross-links are obtained with U7 Sm MUT RNA. The fact that the Sm site also interacts with at least one U7-specific protein is so far unique to U7 RNA and may provide an explanation for the atypical sequence of this site. All described RNA-protein interactions, including that with the 40 kDa protein, already occur in the cytoplasm. An additional cytoplasmic photoadduct obtained with U7 Sm WT and U7 Sm OPT, but not U7 Sm MUT, RNAs is indicative of a protein of 60-80 kDa. The m7G cap structure of U7 Sm WT and U7 Sm OPT RNA becomes hypermethylated. However, the 3mG cap enhances, but is not required for, nuclear accumulation. Finally, U7 Sm WT RNA is functional in histone RNA processing even when bearing an ApppG cap.
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Affiliation(s)
- B Stefanovic
- Abteilung für Entwicklungsbiologie, Universität Bern, Switzerland
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Stefanovic B, Wittop Koning TH, Schümperli D. A synthetic histone pre-mRNA-U7 small nuclear RNA chimera undergoing cis cleavage in the cytoplasm of Xenopus oocytes. Nucleic Acids Res 1995; 23:3152-60. [PMID: 7667091 PMCID: PMC307172 DOI: 10.1093/nar/23.16.3152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The 3' processing of histone pre-mRNAs is a nuclear event in which the U7 small nuclear ribonucleoprotein (snRNP) participates as an essential trans-acting factor. We have constructed a chimeric histone-U7 RNA that when injected into the cytoplasm of Xenopus laevis oocytes assembles into a snRNP-like particle and becomes cleaved at the correct site(s). RNP assembly is a prerequisite for cleavage, but, since neither the RNA nor the RNP appreciably enter the nucleus, cleavage occurs mostly, if not exclusively, in the cytoplasm. Consistent with this, cleavage also occurs in enucleated oocytes or in oocytes which have been depleted of U7 snRNPs. Thus all necessary components for cleavage must be present in the oocyte cytoplasm. The novel cleavage occurs in cis, involving only a single molecule of chimeric RNA with its associated proteins. This reaction is equally dependent upon base pairing interactions between histone spacer sequences and the 5'-end of the U7 moiety as the natural in trans reaction. These results imply that U7 is the only snRNP required for histone RNA processing. Moreover, the chimeric RNA is expected to be useful for further studies of the cleavage and assembly mechanisms of U7 snRNP.
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Affiliation(s)
- B Stefanovic
- Abteilung für Entwicklungsbiologie, Universität Bern, Switzerland
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Williams AS, Marzluff WF. The sequence of the stem and flanking sequences at the 3' end of histone mRNA are critical determinants for the binding of the stem-loop binding protein. Nucleic Acids Res 1995; 23:654-62. [PMID: 7899087 PMCID: PMC306734 DOI: 10.1093/nar/23.4.654] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Complexes of different electrophoretic mobility containing the stem-loop binding protein, a 45 kDa protein, bound to the stem-loop at the 3' end of histone mRNA, are present in both nuclear and cytoplasmic extracts from mammalian cells. We have determined the effect of changes in the loop, in the stem and in the flanking sequences on the affinity of the SLBP for the 3' end of histone mRNA. The sequence of the stem is particularly critical for SLBP binding. Specific sequences both 5' and 3' of the stem-loop are also required for high-affinity binding. Expanding the four base loop by one or two uridines reduced but did not abolish SLBP binding. RNA footprinting experiments show that the flanking sequences on both sides of the stem-loop are critical for efficient binding, but that cleavages in the loop do not abolish binding. Thus all three regions of the RNA sequence contribute to SLBP binding, suggesting that the 26 nt at the 3' end of histone mRNA forms a defined tertiary structure recognized by the SLBP.
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Affiliation(s)
- A S Williams
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599
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