1
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Sun R, Fisher RP. The CDK9-SPT5 axis in control of transcription elongation by RNAPII. J Mol Biol 2024:168746. [PMID: 39147127 DOI: 10.1016/j.jmb.2024.168746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 08/09/2024] [Accepted: 08/09/2024] [Indexed: 08/17/2024]
Abstract
The RNA polymerase II (RNAPII) transcription cycle is regulated at every stage by a network of cyclin-dependent protein kinases (CDKs) and protein phosphatases. Progression of RNAPII from initiation to termination is marked by changing patterns of phosphorylation on the highly repetitive carboxy-terminal domain (CTD) of RPB1, its largest subunit, suggesting the existence of a CTD code. In parallel, the conserved transcription elongation factor SPT5, large subunit of the DRB sensitivity-inducing factor (DSIF), undergoes spatiotemporally regulated changes in phosphorylation state that may be directly linked to the transitions between transcription-cycle phases. Here we review insights gained from recent structural, biochemical, and genetic analyses of human SPT5, which suggest that two of its phosphorylated regions perform distinct functions at different points in transcription. Phosphorylation within a flexible, RNA-binding linker promotes release from the promoter-proximal pause-frequently a rate-limiting step in gene expression-whereas modifications in a repetitive carboxy-terminal region are thought to favor processive elongation, and are removed just prior to termination. Phosphorylations in both motifs depend on CDK9, catalytic subunit of positive transcription elongation factor b (P-TEFb); their different timing of accumulation on chromatin and function during the transcription cycle might reflect their removal by different phosphatases, different kinetics of phosphorylation by CDK9, or both. Perturbations of SPT5 regulation have profound impacts on viability and development in model organisms through largely unknown mechanisms, while enzymes that modify SPT5 have emerged as potential therapeutic targets in cancer; elucidating a putative SPT5 code is therefore a high priority.
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Affiliation(s)
- Rui Sun
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA.
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2
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Fidler E, Dwyer K, Ansari A. Ssu72: a versatile protein with functions in transcription and beyond. Front Mol Biosci 2024; 11:1332878. [PMID: 38304578 PMCID: PMC10830811 DOI: 10.3389/fmolb.2024.1332878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/08/2024] [Indexed: 02/03/2024] Open
Abstract
Eukaryotic transcription is a complex process involving a vast network of protein and RNA factors that influence gene expression. The main player in transcription is the RNA polymerase that synthesizes the RNA from the DNA template. RNA polymerase II (RNAPII) transcribes all protein coding genes and some noncoding RNAs in eukaryotic cells. The polymerase is aided by interacting partners that shuttle it along the gene for initiation, elongation and termination of transcription. One of the many factors that assist RNAPII in transcription of genes is Ssu72. It is a carboxy-terminal-domain (CTD)-phosphatase that plays pleiotropic roles in the transcription cycle. It is essential for cell viability in Saccharomyces cerevisiae, the organism in which it was discovered. The homologues of Ssu72 have been identified in humans, mice, plants, flies, and fungi thereby suggesting the evolutionarily conserved nature of the protein. Recent studies have implicated the factor beyond the confines of transcription in homeostasis and diseases.
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Affiliation(s)
| | | | - Athar Ansari
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
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3
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Zhang Y, Sabatini R. Leishmania PNUTS discriminates between PP1 catalytic subunits through an RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain. J Biol Chem 2023; 299:105432. [PMID: 37926279 PMCID: PMC10731240 DOI: 10.1016/j.jbc.2023.105432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/10/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023] Open
Abstract
Phosphoprotein phosphatase 1 (PP1) associates with specific regulatory subunits to achieve, among other functions, substrate selectivity. Among the eight PP1 isotypes in Leishmania, PP1-8e associates with the regulatory protein PNUTS along with the structural factors JBP3 and Wdr82 in the PJW/PP1 complex that modulates RNA polymerase II (pol II) phosphorylation and transcription termination. Little is known regarding interactions involved in PJW/PP1 complex formation, including how PP1-8e is the selective isotype associated with PNUTS. Here, we show that PNUTS uses an established RVxF-ΦΦ-F motif to bind the PP1 catalytic domain with similar interfacial interactions as mammalian PP1-PNUTS and noncanonical motifs. These atypical interactions involve residues within the PP1-8e catalytic domain and N and C terminus for isoform-specific regulator binding. This work advances our understanding of PP1 isoform selectivity and reveals key roles of PP1 residues in regulator binding. We also explore the role of PNUTS as a scaffold protein for the complex by identifying the C-terminal region involved in binding JBP3 and Wdr82 and impact of PNUTS on the stability of complex components and function in pol II transcription in vivo. Taken together, these studies provide a potential mechanism where multiple motifs within PNUTS are used combinatorially to tune binding affinity to PP1, and the C terminus for JBP3 and Wdr82 association, in the Leishmania PJW/PP1 complex. Overall, our data provide insights in the formation of the PJW/PP1 complex involved in regulating pol II transcription in divergent protozoans where little is understood.
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Affiliation(s)
- Yang Zhang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Robert Sabatini
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA.
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4
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Garg A, Schwer B, Shuman S. Fission yeast poly(A) polymerase active site mutation Y86D alleviates the rad24Δ asp1-H397A synthetic growth defect and up-regulates mRNAs targeted by MTREC and Mmi1. RNA (NEW YORK, N.Y.) 2023; 29:1738-1753. [PMID: 37586723 PMCID: PMC10578478 DOI: 10.1261/rna.079722.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/30/2023] [Indexed: 08/18/2023]
Abstract
Expression of fission yeast Pho1 acid phosphatase is repressed under phosphate-replete conditions by transcription of an upstream prt lncRNA that interferes with the pho1 mRNA promoter. lncRNA-mediated interference is alleviated by genetic perturbations that elicit precocious lncRNA 3'-processing and transcription termination, such as (i) the inositol pyrophosphate pyrophosphatase-defective asp1-H397A allele, which results in elevated levels of IP8, and (ii) absence of the 14-3-3 protein Rad24. Combining rad24Δ with asp1-H397A causes a severe synthetic growth defect. A forward genetic screen for SRA (Suppressor of Rad24 Asp1-H397A) mutations identified a novel missense mutation (Tyr86Asp) of Pla1, the essential poly(A) polymerase subunit of the fission yeast cleavage and polyadenylation factor (CPF) complex. The pla1-Y86D allele was viable but slow-growing in an otherwise wild-type background. Tyr86 is a conserved active site constituent that contacts the RNA primer 3' nt and the incoming ATP. The Y86D mutation elicits a severe catalytic defect in RNA-primed poly(A) synthesis in vitro and in binding to an RNA primer. Yet, analyses of specific mRNAs indicate that poly(A) tails in pla1-Y86D cells are not different in size than those in wild-type cells, suggesting that other RNA interactors within CPF compensate for the defects of isolated Pla1-Y86D. Transcriptome profiling of pla1-Y86D cells revealed the accumulation of multiple RNAs that are normally rapidly degraded by the nuclear exosome under the direction of the MTREC complex, with which Pla1 associates. We suggest that Pla1-Y86D is deficient in the hyperadenylation of MTREC targets that precedes their decay by the exosome.
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Affiliation(s)
- Angad Garg
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
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5
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Sanchez AM, Schwer B, Jork N, Jessen HJ, Shuman S. Activities, substrate specificity, and genetic interactions of fission yeast Siw14, a cysteinyl-phosphatase-type inositol pyrophosphatase. mBio 2023; 14:e0205623. [PMID: 37772819 PMCID: PMC10653929 DOI: 10.1128/mbio.02056-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 08/09/2023] [Indexed: 09/30/2023] Open
Abstract
IMPORTANCE The inositol pyrophosphate signaling molecule 1,5-IP8 modulates fission yeast phosphate homeostasis via its action as an agonist of RNA 3'-processing and transcription termination. Cellular 1,5-IP8 levels are determined by a balance between the activities of the inositol polyphosphate kinase Asp1 and several inositol pyrophosphatase enzymes. Here, we characterize Schizosaccharomyces pombe Siw14 (SpSiw14) as a cysteinyl-phosphatase-family pyrophosphatase enzyme capable of hydrolyzing the phosphoanhydride substrates inorganic pyrophosphate, inorganic polyphosphate, and inositol pyrophosphates 5-IP7, 1-IP7, and 1,5-IP8. Genetic analyses implicate SpSiw14 in 1,5-IP8 catabolism in vivo, insofar as: loss of SpSiw14 activity is lethal in the absence of the Nudix-type inositol pyrophosphatase enzyme Aps1; and siw14∆ aps1∆ lethality depends on synthesis of 1,5-IP8 by the Asp1 kinase. Suppression of siw14∆ aps1∆ lethality by loss-of-function mutations of 3'-processing/termination factors points to precocious transcription termination as the cause of 1,5-IP8 toxicosis.
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Affiliation(s)
- Ana M. Sanchez
- Molecular Biology Program, Sloan Kettering Institute, New York, New York, USA
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, New York, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
| | - Nikolaus Jork
- Institute of Organic Chemistry and Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Henning J. Jessen
- Institute of Organic Chemistry and Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Stewart Shuman
- Molecular Biology Program, Sloan Kettering Institute, New York, New York, USA
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6
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Zhang Y, Sabatini R. Leishmania PNUTS discriminates between PP1 catalytic subunits through a RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.20.558696. [PMID: 37790576 PMCID: PMC10542515 DOI: 10.1101/2023.09.20.558696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
PP1 phosphatases lack substrate specificity and associate with specific regulatory subunits to achieve selectivity. Among the eight PP1 isotypes in Leishmania, PP1-8e associates with the regulatory protein PNUTS along with the structural factors JBP3 and Wdr82 in the PJW/PP1 complex that modulates RNA polymerase II (Pol II) phosphorylation and transcription termination. Little is known regarding interactions involved in PJW/PP1 complex formation, including how PP1-8e is the selective isotype associated with PNUTS. Here, we show that PNUTS uses an established RVxF-ΦΦ-F motif to bind the PP1 catalytic domain with similar interfacial interactions as mammalian PP1- PNUTS and non-canonical motifs. These atypical interactions involve residues within the PP1-8e catalytic domain and N- and C-terminus for isoform specific regulator binding. This work advances our understanding of PP1 isoform selectivity and reveals key roles of PP1 residues in regulator binding. We also explore the role of PNUTS as a scaffold protein for the complex by identifying the C-terminal region involved in binding JBP3 and Wdr82, and impact of PNUTS on the stability of complex components and function in Pol II transcription in vivo . Taken together, these studies provide a potential mechanism where multiple motifs within PNUTS are used combinatorially to tune binding affinity to PP1, and the C-termini for independent binding of JBP3 and Wdr82, in the Leishmania PJW/PP1 complex. Overall, our data provide insights in the formation of the PJW/PP1 complex involved in regulating Pol II transcription in divergent protozoans where little is understood.
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7
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Sanchez AM, Garg A, Schwer B, Shuman S. Duf89 abets lncRNA control of fission yeast phosphate homeostasis via its antagonism of precocious lncRNA transcription termination. RNA (NEW YORK, N.Y.) 2023; 29:808-825. [PMID: 36882296 PMCID: PMC10187668 DOI: 10.1261/rna.079595.123] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 02/13/2023] [Indexed: 05/18/2023]
Abstract
Fission yeast phosphate homeostasis gene pho1 is actively repressed during growth in phosphate-rich medium by transcription in cis of a long noncoding (lnc) RNA from the 5' flanking prt(nc-pho1) gene. Pho1 expression is: (i) derepressed by genetic maneuvers that favor precocious lncRNA 3'-processing and termination, in response to DSR and PAS signals in prt; and (ii) hyperrepressed in genetic backgrounds that dampen 3'-processing/termination efficiency. Governors of 3'-processing/termination include the RNA polymerase CTD code, the CPF (cleavage and polyadenylation factor) complex, termination factors Seb1 and Rhn1, and the inositol pyrophosphate signaling molecule 1,5-IP8 Here, we present genetic and biochemical evidence that fission yeast Duf89, a metal-dependent phosphatase/pyrophosphatase, is an antagonist of precocious 3'-processing/termination. We show that derepression of pho1 in duf89Δ cells correlates with squelching the production of full-length prt lncRNA and is erased or attenuated by: (i) DSR/PAS mutations in prt; (ii) loss-of-function mutations in components of the 3'-processing and termination machinery; (iii) elimination of the CTD Thr4-PO4 mark; (iv) interdicting CTD prolyl isomerization by Pin1; (v) inactivating the Asp1 kinase that synthesizes IP8; and (vi) loss of the putative IP8 sensor Spx1. The findings that duf89Δ is synthetically lethal with pho1-derepressive mutations CTD-S7A and aps1Δ-and that this lethality is rescued by CTD-T4A, CPF/Rhn1/Pin1 mutations, and spx1Δ-implicate Duf89 more broadly as a collaborator in cotranscriptional regulation of essential fission yeast genes. The duf89-D252A mutation, which abolishes Duf89 phosphohydrolase activity, phenocopied duf89 +, signifying that duf89Δ phenotypes are a consequence of Duf89 protein absence, not absence of Duf89 catalysis.
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Affiliation(s)
- Ana M Sanchez
- Molecular Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, New York 10065, USA
| | - Angad Garg
- Molecular Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
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8
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Archambault V, Li J, Emond-Fraser V, Larouche M. Dephosphorylation in nuclear reassembly after mitosis. Front Cell Dev Biol 2022; 10:1012768. [PMID: 36268509 PMCID: PMC9576876 DOI: 10.3389/fcell.2022.1012768] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 08/31/2022] [Indexed: 11/13/2022] Open
Abstract
In most animal cell types, the interphase nucleus is largely disassembled during mitotic entry. The nuclear envelope breaks down and chromosomes are compacted into separated masses. Chromatin organization is also mostly lost and kinetochores assemble on centromeres. Mitotic protein kinases play several roles in inducing these transformations by phosphorylating multiple effector proteins. In many of these events, the mechanistic consequences of phosphorylation have been characterized. In comparison, how the nucleus reassembles at the end of mitosis is less well understood in mechanistic terms. In recent years, much progress has been made in deciphering how dephosphorylation of several effector proteins promotes nuclear envelope reassembly, chromosome decondensation, kinetochore disassembly and interphase chromatin organization. The precise roles of protein phosphatases in this process, in particular of the PP1 and PP2A groups, are emerging. Moreover, how these enzymes are temporally and spatially regulated to ensure that nuclear reassembly progresses in a coordinated manner has been partly uncovered. This review provides a global view of nuclear reassembly with a focus on the roles of dephosphorylation events. It also identifies important open questions and proposes hypotheses.
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Affiliation(s)
- Vincent Archambault
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC, Canada
- *Correspondence: Vincent Archambault,
| | - Jingjing Li
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Virginie Emond-Fraser
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Myreille Larouche
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
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Cleavage-Polyadenylation Factor Cft1 and SPX Domain Proteins Are Agents of Inositol Pyrophosphate Toxicosis in Fission Yeast. mBio 2022; 13:e0347621. [PMID: 35012333 PMCID: PMC8749416 DOI: 10.1128/mbio.03476-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Inositol pyrophosphate (IPP) dynamics govern expression of the fission yeast phosphate homeostasis regulon via their effects on lncRNA-mediated transcription interference. The growth defects (ranging from sickness to lethality) elicited by fission yeast mutations that inactivate IPP pyrophosphatase enzymes are exerted via the agonistic effects of too much 1,5-IP8 on RNA 3'-processing and transcription termination. To illuminate determinants of IPP toxicosis, we conducted a genetic screen for spontaneous mutations that suppressed the sickness of Asp1 pyrophosphatase mutants. We identified a missense mutation, C823R, in the essential Cft1 subunit of the cleavage and polyadenylation factor complex that suppresses even lethal Asp1 IPP pyrophosphatase mutations, thereby fortifying the case for 3'-processing/termination as the target of IPP toxicity. The suppressor screen also identified Gde1 and Spx1 (SPAC6B12.07c), both of which have an IPP-binding SPX domain and both of which are required for lethality elicited by Asp1 mutations. A survey of other SPX proteins in the proteome identified the Vtc4 and Vtc2 subunits of the vacuolar polyphosphate polymerase as additional agents of IPP toxicosis. Gde1, Spx1, and Vtc4 contain enzymatic modules (glycerophosphodiesterase, RING finger ubiquitin ligase, and polyphosphate polymerase, respectively) fused to their IPP-sensing SPX domains. Structure-guided mutagenesis of the IPP-binding sites and the catalytic domains of Gde1 and Spx1 indicated that both modules are necessary to elicit IPP toxicity. Whereas Vtc4 polymerase catalytic activity is required for IPP toxicity, its IPP-binding site is not. Epistasis analysis, transcriptome profiling, and assays of Pho1 expression implicate Spx1 as a transducer of IP8 signaling to the 3'-processing/transcription termination machinery. IMPORTANCE Impeding the catabolism of the inositol pyrophosphate (IPP) signaling molecule IP8 is cytotoxic to fission yeast. Here, by performing a genetic suppressor screen, we identified several cellular proteins required for IPP toxicosis. Alleviation of IPP lethality by a missense mutation in the essential Cft1 subunit of the cleavage and polyadenylation factor consolidates previous evidence that toxicity results from IP8 action as an agonist of RNA 3'-processing and transcription termination. Novel findings are that IP8 toxicity depends on IPP-sensing SPX domain proteins with associated enzymatic functions: Gde1 (glycerophosphodiesterase), Spx1 (ubiquitin ligase), and Vtc2/4 (polyphosphate polymerase). The effects of Spx1 deletion on phosphate homeostasis imply a role for Spx1 in communicating an IP8-driven signal to the transcription and RNA processing apparatus.
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10
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Garg A, Shuman S, Schwer B. Genetic screen for suppression of transcriptional interference reveals fission yeast 14-3-3 protein Rad24 as an antagonist of precocious Pol2 transcription termination. Nucleic Acids Res 2021; 50:803-819. [PMID: 34967420 PMCID: PMC8789043 DOI: 10.1093/nar/gkab1263] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/01/2021] [Accepted: 12/13/2021] [Indexed: 11/20/2022] Open
Abstract
Expression of fission yeast Pho1 acid phosphatase is repressed under phosphate-replete conditions by transcription of an upstream prt lncRNA that interferes with the pho1 mRNA promoter. lncRNA control of pho1 mRNA synthesis is influenced by inositol pyrophosphate (IPP) kinase Asp1, deletion of which results in pho1 hyper-repression. A forward genetic screen for ADS (Asp1 Deletion Suppressor) mutations identified the 14–3–3 protein Rad24 as a governor of phosphate homeostasis. Production of full-length interfering prt lncRNA was squelched in rad24Δ cells, concomitant with increased production of pho1 mRNA and increased Pho1 activity, while shorter precociously terminated non-interfering prt transcripts persisted. Epistasis analysis showed that pho1 de-repression by rad24Δ depends on: (i) 3′-processing and transcription termination factors CPF, Pin1, and Rhn1; and (ii) Threonine-4 of the Pol2 CTD. Combining rad24Δ with the IPP pyrophosphatase-dead asp1-H397A allele caused a severe synthetic growth defect that was ameliorated by loss-of-function mutations in CPF, Pin1, and Rhn1, and by CTD phospho-site mutations T4A and Y1F. Rad24 function in repressing pho1 was effaced by mutation of its phosphate-binding pocket. Our findings instate a new role for a 14–3–3 protein as an antagonist of precocious RNA 3′-processing/termination.
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Affiliation(s)
- Angad Garg
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Beate Schwer
- Dept. of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
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11
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Transcription and chromatin-based surveillance mechanism controls suppression of cryptic antisense transcription. Cell Rep 2021; 36:109671. [PMID: 34496258 PMCID: PMC8441049 DOI: 10.1016/j.celrep.2021.109671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/26/2020] [Accepted: 08/13/2021] [Indexed: 12/25/2022] Open
Abstract
Phosphorylation of the RNA polymerase II C-terminal domain Y1S2P3T4S5P6S7 consensus sequence coordinates key events during transcription, and its deregulation leads to defects in transcription and RNA processing. Here, we report that the histone deacetylase activity of the fission yeast Hos2/Set3 complex plays an important role in suppressing cryptic initiation of antisense transcription when RNA polymerase II phosphorylation is dysregulated due to the loss of Ssu72 phosphatase. Interestingly, although single Hos2 and Set3 mutants have little effect, loss of Hos2 or Set3 combined with ssu72Δ results in a synergistic increase in antisense transcription globally and correlates with elevated sensitivity to genotoxic agents. We demonstrate a key role for the Ssu72/Hos2/Set3 mechanism in the suppression of cryptic antisense transcription at the 3' end of convergent genes that are most susceptible to these defects, ensuring the fidelity of gene expression within dense genomes of simple eukaryotes.
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12
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Genetic screen for suppression of transcriptional interference identifies a gain-of-function mutation in Pol2 termination factor Seb1. Proc Natl Acad Sci U S A 2021; 118:2108105118. [PMID: 34389684 DOI: 10.1073/pnas.2108105118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The system of long noncoding RNA (lncRNA)-mediated transcriptional interference that represses fission yeast phosphate homoeostasis gene pho1 provides a sensitive readout of genetic influences on cotranscriptional 3'-processing and termination and a tool for discovery of regulators of this phase of the Pol2 transcription cycle. Here, we conducted a genetic screen for relief of transcriptional interference that unveiled a mechanism by which Pol2 termination is enhanced via a gain-of-function mutation, G476S, in the RNA-binding domain of an essential termination factor, Seb1. The genetic and physical evidence for gain-of-function is compelling: 1) seb1-G476S de-represses pho1 and tgp1, both of which are subject to lncRNA-mediated transcriptional interference; 2) seb1-G476S elicits precocious lncRNA transcription termination in response to lncRNA 5'-proximal poly(A) signals; 3) seb1-G476S derepression of pho1 is effaced by loss-of-function mutations in cleavage and polyadenylation factor (CPF) subunits and termination factor Rhn1; 4) synthetic lethality of seb1-G476S with pho1 derepressive mutants rpb1-CTD-S7A and aps1∆ is rescued by CPF/Rhn1 loss-of-function alleles; and 5) seb1-G476S elicits an upstream shift in poly(A) site preference in several messenger RNA genes. A crystal structure of the Seb1-G476S RNA-binding domain indicates potential for gain of contacts from Ser476 to RNA nucleobases. To our knowledge, this is a unique instance of a gain-of-function phenotype in a eukaryal transcription termination protein.
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13
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CDK9 keeps RNA polymerase II on track. Cell Mol Life Sci 2021; 78:5543-5567. [PMID: 34146121 PMCID: PMC8257543 DOI: 10.1007/s00018-021-03878-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/26/2021] [Accepted: 06/08/2021] [Indexed: 12/30/2022]
Abstract
Cyclin-dependent kinase 9 (CDK9), the kinase component of positive transcription elongation factor b (P-TEFb), is essential for transcription of most protein-coding genes by RNA polymerase II (RNAPII). By releasing promoter-proximally paused RNAPII into gene bodies, CDK9 controls the entry of RNAPII into productive elongation and is, therefore, critical for efficient synthesis of full-length messenger (m)RNAs. In recent years, new players involved in P-TEFb-dependent processes have been identified and an important function of CDK9 in coordinating elongation with transcription initiation and termination has been unveiled. As the regulatory functions of CDK9 in gene expression continue to expand, a number of human pathologies, including cancers, have been associated with aberrant CDK9 activity, underscoring the need to properly regulate CDK9. Here, I provide an overview of CDK9 function and regulation, with an emphasis on CDK9 dysregulation in human diseases.
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14
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Cossa G, Parua PK, Eilers M, Fisher RP. Protein phosphatases in the RNAPII transcription cycle: erasers, sculptors, gatekeepers, and potential drug targets. Genes Dev 2021; 35:658-676. [PMID: 33888562 PMCID: PMC8091971 DOI: 10.1101/gad.348315.121] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In this review, Cossa et al. discuss the current knowledge and outstanding questions about phosphatases in the context of the RNAPII transcription cycle. The transcription cycle of RNA polymerase II (RNAPII) is governed at multiple points by opposing actions of cyclin-dependent kinases (CDKs) and protein phosphatases, in a process with similarities to the cell division cycle. While important roles of the kinases have been established, phosphatases have emerged more slowly as key players in transcription, and large gaps remain in understanding of their precise functions and targets. Much of the earlier work focused on the roles and regulation of sui generis and often atypical phosphatases—FCP1, Rtr1/RPAP2, and SSU72—with seemingly dedicated functions in RNAPII transcription. Decisive roles in the transcription cycle have now been uncovered for members of the major phosphoprotein phosphatase (PPP) family, including PP1, PP2A, and PP4—abundant enzymes with pleiotropic roles in cellular signaling pathways. These phosphatases appear to act principally at the transitions between transcription cycle phases, ensuring fine control of elongation and termination. Much is still unknown, however, about the division of labor among the PPP family members, and their possible regulation by or of the transcriptional kinases. CDKs active in transcription have recently drawn attention as potential therapeutic targets in cancer and other diseases, raising the prospect that the phosphatases might also present opportunities for new drug development. Here we review the current knowledge and outstanding questions about phosphatases in the context of the RNAPII transcription cycle.
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Affiliation(s)
- Giacomo Cossa
- Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Pabitra K Parua
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Martin Eilers
- Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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15
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Rivosecchi J, Jost D, Vachez L, Gautier FD, Bernard P, Vanoosthuyse V. RNA polymerase backtracking results in the accumulation of fission yeast condensin at active genes. Life Sci Alliance 2021; 4:4/6/e202101046. [PMID: 33771877 PMCID: PMC8046420 DOI: 10.26508/lsa.202101046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/04/2021] [Accepted: 03/07/2021] [Indexed: 12/23/2022] Open
Abstract
Using both experiments and mathematical modelling, the authors show that RNA polymerase backtracking contributes to the accumulation of condensin in the termination zone of active genes. The mechanisms leading to the accumulation of the SMC complexes condensins around specific transcription units remain unclear. Observations made in bacteria suggested that RNA polymerases (RNAPs) constitute an obstacle to SMC translocation, particularly when RNAP and SMC travel in opposite directions. Here we show in fission yeast that gene termini harbour intrinsic condensin-accumulating features whatever the orientation of transcription, which we attribute to the frequent backtracking of RNAP at gene ends. Consistent with this, to relocate backtracked RNAP2 from gene termini to gene bodies was sufficient to cancel the accumulation of condensin at gene ends and to redistribute it evenly within transcription units, indicating that RNAP backtracking may play a key role in positioning condensin. Formalization of this hypothesis in a mathematical model suggests that the inclusion of a sub-population of RNAP with longer dwell-times is essential to fully recapitulate the distribution profiles of condensin around active genes. Taken together, our data strengthen the idea that dense arrays of proteins tightly bound to DNA alter the distribution of condensin on chromosomes.
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Affiliation(s)
- Julieta Rivosecchi
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5239, Lyon, France
| | - Daniel Jost
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5239, Lyon, France
| | - Laetitia Vachez
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5239, Lyon, France
| | - François Dr Gautier
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5239, Lyon, France
| | - Pascal Bernard
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5239, Lyon, France
| | - Vincent Vanoosthuyse
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5239, Lyon, France
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16
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Lee SY, Hung S, Esnault C, Pathak R, Johnson KR, Bankole O, Yamashita A, Zhang H, Levin HL. Dense Transposon Integration Reveals Essential Cleavage and Polyadenylation Factors Promote Heterochromatin Formation. Cell Rep 2021; 30:2686-2698.e8. [PMID: 32101745 PMCID: PMC9497450 DOI: 10.1016/j.celrep.2020.01.094] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 10/18/2019] [Accepted: 01/27/2020] [Indexed: 11/24/2022] Open
Abstract
Heterochromatin functions as a scaffold for factors responsible for gene
silencing and chromosome segregation. Heterochromatin can be assembled by
multiple pathways, including RNAi and RNA surveillance. We identified factors
that form heterochromatin using dense profiles of transposable element
integration in Schizosaccharomyces pombe. The candidates
include a large number of essential proteins such as four canonical mRNA
cleavage and polyadenylation factors. We find that Iss1, a subunit of the
poly(A) polymerase module, plays a role in forming heterochromatin in centromere
repeats that is independent of RNAi. Genome-wide maps reveal that Iss1
accumulates at genes regulated by RNA surveillance. Iss1 interacts with RNA
surveillance factors Mmi1 and Rrp6, and importantly, Iss1 contributes to RNA
elimination that forms heterochromatin at meiosis genes. Our profile of
transposable element integration supports the model that a network of mRNA
cleavage and polyadenylation factors coordinates RNA surveillance, including the
mechanism that forms heterochromatin at meiotic genes. Lee et al. use dense profiles of transposon integration to identify genes
important for the formation of heterochromatin. Among many candidates, Iss1 is a
canonical mRNA cleavage and polyadenylation factor found to be important for
heterochromatin at meiotic genes by recruiting the nuclear exosome.
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Affiliation(s)
- Si Young Lee
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stevephen Hung
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Caroline Esnault
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rakesh Pathak
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kory R Johnson
- Bioinformatics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Oluwadamilola Bankole
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Akira Yamashita
- National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Hongen Zhang
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Henry L Levin
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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17
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Benjamin B, Sanchez AM, Garg A, Schwer B, Shuman S. Structure-function analysis of fission yeast cleavage and polyadenylation factor (CPF) subunit Ppn1 and its interactions with Dis2 and Swd22. PLoS Genet 2021; 17:e1009452. [PMID: 33711009 PMCID: PMC7990198 DOI: 10.1371/journal.pgen.1009452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 03/24/2021] [Accepted: 02/26/2021] [Indexed: 12/20/2022] Open
Abstract
Fission yeast Cleavage and Polyadenylation Factor (CPF), a 13-subunit complex, executes the cotranscriptional 3' processing of RNA polymerase II (Pol2) transcripts that precedes transcription termination. The three-subunit DPS sub-complex of CPF, consisting of a PP1-type phosphoprotein phosphatase Dis2, a WD-repeat protein Swd22, and a putative phosphatase regulatory factor Ppn1, associates with the CPF core to form the holo-CPF assembly. Here we probed the functional, physical, and genetic interactions of DPS by focusing on the Ppn1 subunit, which mediates association of DPS with the core. Transcriptional profiling by RNA-seq defined limited but highly concordant sets of protein-coding genes that were dysregulated in ppn1Δ, swd22Δ and dis2Δ cells, which included the DPSΔ down-regulated phosphate homeostasis genes pho1 and pho84 that are controlled by lncRNA-mediated transcriptional interference. Essential and inessential modules of the 710-aa Ppn1 protein were defined by testing the effects of Ppn1 truncations in multiple genetic backgrounds in which Ppn1 is required for growth. An N-terminal 172-aa disordered region was dispensable and its deletion alleviated hypomorphic phenotypes caused by deleting C-terminal aa 640-710. A TFIIS-like domain (aa 173-330) was not required for viability but was important for Ppn1 activity in phosphate homeostasis. Distinct sites within Ppn1 for binding to Dis2 (spanning Ppn1 aa 506 to 532) and Swd22 (from Ppn1 aa 533 to 578) were demarcated by yeast two-hybrid assays. Dis2 interaction-defective missense mutants of full-length Ppn1 (that retained Swd22 interaction) were employed to show that binding to Dis2 (or its paralog Sds21) was necessary for Ppn1 biological activity. Ppn1 function was severely compromised by missense mutations that selectively affected its binding to Swd22.
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Affiliation(s)
- Bradley Benjamin
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, New York, United States of America
| | - Ana M. Sanchez
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, New York, United States of America
| | - Angad Garg
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
| | - Beate Schwer
- Dept. of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (BS); (SS)
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- * E-mail: (BS); (SS)
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18
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Garg A, Sanchez AM, Schwer B, Shuman S. Transcriptional profiling of fission yeast RNA polymerase II CTD mutants. RNA (NEW YORK, N.Y.) 2021; 27:rna.078682.121. [PMID: 33579781 PMCID: PMC8051263 DOI: 10.1261/rna.078682.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/11/2021] [Indexed: 05/08/2023]
Abstract
The carboxyl-terminal domain (CTD) of RNA polymerase II (Pol2) consists of tandem repeats of a consensus heptapeptide Y1 S2 P3 T4 S5 P6 S7 The CTD recruits numerous proteins that drive or regulate gene expression. The trafficking of CTD-interacting proteins is orchestrated by remodeling CTD primary structure via Ser/Thr/Tyr phosphorylation and proline cis-trans isomerization, which collectively inscribe a CTD code. The fission yeast CTD consists of 29 heptad repeats. To decipher the output of the fission yeast CTD code, we genetically manipulated CTD length and amino acid content and then gauged the effects of these changes on gene expression. Whereas deleting 11 consensus heptads has no obvious effect on fission yeast growth, RNA-seq revealed that 25% of the protein-coding transcripts were dysregulated by CTD truncation. We profiled the transcriptomes of full-length CTD mutants, in which: all Tyr1 residues were replaced by Phe; all Ser2, Thr4, or Ser7 positions were changed to Ala; and half of the essential CTD code "letters" Pro3, Ser5, and Pro6 were mutated to Ala. Overlapping RNA-seq profiles suggested that a quarter of the complement of up-regulated mRNAs and half of the down-regulated mRNAs seen in full-length CTD mutants might be attributable to a decrement in wild-type CTD heptad number. Concordant mutant-specific transcriptional profiles were observed for Y1F, S2A, and T4A cells, and for P6•P6A and S5•S5A cells, suggesting that Tyr1-Ser2-Thr4 and Ser5-Pro6 comprise distinct "words" in the fission yeast CTD code. The phosphate regulon, which is repressed by lncRNA-mediated transcription interference, is de-repressed by CTD mutations P6•P6A and S5•S5A. De-repression of pho1 in P6•P6A and S5•S5A cells depends on cleavage and polyadenylation factor subunits Swd22 and Ppn1 and transcription termination factor Rhn1, signifying that Pro6 and Ser5 mutations elicit precocious lncRNA 3'-processing/termination.
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19
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Liu C, Zhang W, Xing W. Diverse and conserved roles of the protein Ssu72 in eukaryotes: from yeast to higher organisms. Curr Genet 2020; 67:195-206. [PMID: 33244642 DOI: 10.1007/s00294-020-01132-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/04/2020] [Accepted: 11/06/2020] [Indexed: 01/21/2023]
Abstract
Gene transcription is a complex biological process that involves a set of factors, enzymes and nucleotides. Ssu72 plays a crucial role in every step of gene transcription. RNA polymerase II (RNAPII) occupies an important position in the synthesis of mRNAs. The largest subunit of RNAPII, Rpb1, harbors its C-terminal domain (CTD), which participates in the initiation, elongation and termination of transcription. The CTD consists of heptad repeats of the consensus motif Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7 and is highly conserved among different species. The CTD is flexible in structure and undergoes conformational changes in response to serine phosphorylation and proline isomerization, which are regulated by specific kinases/phosphatases and isomerases, respectively. Ssu72 is a CTD phosphatase with catalytic activity against phosphorylated Ser5 and Ser7. The isomerization of Pro6 affects the binding of Ssu72 to its substrate. Ssu72 can also indirectly change the phosphorylation status of Ser2. In addition, Ssu72 is a member of the 3'-end cleavage and polyadenylation factor (CPF) complex. Together with other CPF components, Ssu72 regulates the 3'-end processing of premature mRNA. Recent studies have revealed other roles of Ssu72, including its roles in balancing phosphate homeostasis and controlling chromosome behaviors, which should be further explored. In conclusion, the protein Ssu72 is an enzyme worthy of attention, not confined to its role in gene transcription.
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Affiliation(s)
- Changfu Liu
- Department of Interventional Treatment, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China
| | - Weihao Zhang
- Department of Interventional Treatment, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China
| | - Wenge Xing
- Department of Interventional Treatment, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China.
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20
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Garg A, Shuman S, Schwer B. A genetic screen for suppressors of hyper-repression of the fission yeast PHO regulon by Pol2 CTD mutation T4A implicates inositol 1-pyrophosphates as agonists of precocious lncRNA transcription termination. Nucleic Acids Res 2020; 48:10739-10752. [PMID: 33010152 PMCID: PMC7641756 DOI: 10.1093/nar/gkaa776] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/03/2020] [Accepted: 09/29/2020] [Indexed: 12/23/2022] Open
Abstract
Fission yeast phosphate homeostasis genes are repressed in phosphate-rich medium by transcription of upstream lncRNAs that interferes with activation of the flanking mRNA promoters. lncRNA control of PHO gene expression is influenced by the Thr4 phospho-site in the RNA polymerase II CTD and the 3′ processing/termination factors CPF and Rhn1, mutations of which result in hyper-repression of the PHO regulon. Here, we performed a forward genetic screen for mutations that de-repress Pho1 acid phosphatase expression in CTD-T4A cells. Sequencing of 18 independent STF (Suppressor of Threonine Four) isolates revealed, in every case, a mutation in the C-terminal pyrophosphatase domain of Asp1, a bifunctional inositol pyrophosphate (IPP) kinase/pyrophosphatase that interconverts 5-IP7 and 1,5-IP8. Focused characterization of two STF strains identified 51 coding genes coordinately upregulated vis-à-vis the parental T4A strain, including all three PHO regulon genes (pho1, pho84, tgp1). Whereas these STF alleles—asp1-386(Stop) and asp1-493(Stop)—were lethal in a wild-type CTD background, they were viable in combination with mutations in CPF and Rhn1, in which context Pho1 was also de-repressed. Our findings implicate Asp1 pyrophosphatase in constraining 1,5-IP8 or 1-IP7 synthesis by Asp1 kinase, without which 1-IPPs can accumulate to toxic levels that elicit precocious termination by CPF/Rhn1.
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Affiliation(s)
- Angad Garg
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
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21
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Shuman S. Transcriptional interference at tandem lncRNA and protein-coding genes: an emerging theme in regulation of cellular nutrient homeostasis. Nucleic Acids Res 2020; 48:8243-8254. [PMID: 32720681 PMCID: PMC7470944 DOI: 10.1093/nar/gkaa630] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 07/10/2020] [Accepted: 07/26/2020] [Indexed: 12/29/2022] Open
Abstract
Tandem transcription interference occurs when the act of transcription from an upstream promoter suppresses utilization of a co-oriented downstream promoter. Because eukaryal genomes are liberally interspersed with transcription units specifying long non-coding (lnc) RNAs, there are many opportunities for lncRNA synthesis to negatively affect a neighboring protein-coding gene. Here, I review two eukaryal systems in which lncRNA interference with mRNA expression underlies a regulated biological response to nutrient availability. Budding yeast SER3 is repressed under serine-replete conditions by transcription of an upstream SRG1 lncRNA that traverses the SER3 promoter and elicits occlusive nucleosome rearrangements. SER3 is de-repressed by serine withdrawal, which leads to shut-off of SRG1 synthesis. The fission yeast phosphate homeostasis (PHO) regulon comprises three phosphate acquisition genes – pho1, pho84, and tgp1 – that are repressed under phosphate-replete conditions by 5′ flanking lncRNAs prt, prt2, and nc-tgp1, respectively. lncRNA transcription across the PHO mRNA promoters displaces activating transcription factor Pho7. PHO mRNAs are transcribed during phosphate starvation when lncRNA synthesis abates. The PHO regulon is de-repressed in phosphate-replete cells by genetic manipulations that favor ‘precocious’ lncRNA 3′-processing/termination upstream of the mRNA promoters. PHO lncRNA termination is governed by the Pol2 CTD code and is subject to metabolite control by inositol pyrophosphates.
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Affiliation(s)
- Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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22
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Sanchez AM, Garg A, Shuman S, Schwer B. Genetic interactions and transcriptomics implicate fission yeast CTD prolyl isomerase Pin1 as an agent of RNA 3' processing and transcription termination that functions via its effects on CTD phosphatase Ssu72. Nucleic Acids Res 2020; 48:4811-4826. [PMID: 32282918 PMCID: PMC7229847 DOI: 10.1093/nar/gkaa212] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/19/2020] [Accepted: 03/24/2020] [Indexed: 01/05/2023] Open
Abstract
The phosphorylation pattern of Pol2 CTD Y1S2P3T4S5P6S7 repeats comprises an informational code coordinating transcription and RNA processing. cis-trans isomerization of CTD prolines expands the scope of the code in ways that are not well understood. Here we address this issue via analysis of fission yeast peptidyl-prolyl isomerase Pin1. A pin1Δ allele that does not affect growth per se is lethal in the absence of cleavage-polyadenylation factor (CPF) subunits Ppn1 and Swd22 and elicits growth defects absent CPF subunits Ctf1 and Dis2 and termination factor Rhn1. Whereas CTD S2A, T4A, and S7A mutants thrive in combination with pin1Δ, a Y1F mutant does not, nor do CTD mutants in which half the Pro3 or Pro6 residues are replaced by alanine. Phosphate-acquisition genes pho1, pho84 and tgp1 are repressed by upstream lncRNAs and are sensitive to changes in lncRNA 3' processing/termination. pin1Δ hyper-represses PHO gene expression and erases the de-repressive effect of CTD-S7A. Transcriptional profiling delineated sets of 56 and 22 protein-coding genes that are down-regulated and up-regulated in pin1Δ cells, respectively, 77% and 100% of which are downregulated/upregulated when the cis-proline-dependent Ssu72 CTD phosphatase is inactivated. Our results implicate Pin1 as a positive effector of 3' processing/termination that acts via Ssu72.
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Affiliation(s)
- Ana M Sanchez
- Dept. of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY 10065, USA
| | - Angad Garg
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
- To whom correspondence should be addressed. Tel: +1 212 639 7145;
| | - Beate Schwer
- Dept. of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
- Correspondence may also be addressed to Beate Schwer. Tel: +1 212 746 6518;
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23
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Parua PK, Kalan S, Benjamin B, Sansó M, Fisher RP. Distinct Cdk9-phosphatase switches act at the beginning and end of elongation by RNA polymerase II. Nat Commun 2020; 11:4338. [PMID: 32859893 PMCID: PMC7455706 DOI: 10.1038/s41467-020-18173-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/10/2020] [Indexed: 12/21/2022] Open
Abstract
Reversible phosphorylation of Pol II and accessory factors helps order the transcription cycle. Here, we define two kinase-phosphatase switches that operate at different points in human transcription. Cdk9/cyclin T1 (P-TEFb) catalyzes inhibitory phosphorylation of PP1 and PP4 complexes that localize to 3′ and 5′ ends of genes, respectively, and have overlapping but distinct specificities for Cdk9-dependent phosphorylations of Spt5, a factor instrumental in promoter-proximal pausing and elongation-rate control. PP1 dephosphorylates an Spt5 carboxy-terminal repeat (CTR), but not Spt5-Ser666, a site between Kyrpides-Ouzounis-Woese (KOW) motifs 4 and 5, whereas PP4 can target both sites. In vivo, Spt5-CTR phosphorylation decreases as transcription complexes pass the cleavage and polyadenylation signal (CPS) and increases upon PP1 depletion, consistent with a PP1 function in termination first uncovered in yeast. Depletion of PP4-complex subunits increases phosphorylation of both Ser666 and the CTR, and promotes redistribution of promoter-proximally paused Pol II into gene bodies. These results suggest that switches comprising Cdk9 and either PP4 or PP1 govern pause release and the elongation-termination transition, respectively. Cdk9 (P-TEFb) and its substrate Spt5 influence events throughout the transcription cycle. Here, the authors define two switches with the potential to regulate promoter-proximal pause release and termination, respectively containing phosphatases PP4 and PP1, which are both inhibited by Cdk9, but have different specificities for sites on Spt5 and occupy opposite ends of genes.
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Affiliation(s)
- Pabitra K Parua
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA
| | - Sampada Kalan
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA
| | - Bradley Benjamin
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA
| | - Miriam Sansó
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029-6574, USA.
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24
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Vo TV, Dhakshnamoorthy J, Larkin M, Zofall M, Thillainadesan G, Balachandran V, Holla S, Wheeler D, Grewal SIS. CPF Recruitment to Non-canonical Transcription Termination Sites Triggers Heterochromatin Assembly and Gene Silencing. Cell Rep 2020; 28:267-281.e5. [PMID: 31269446 DOI: 10.1016/j.celrep.2019.05.107] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/16/2019] [Accepted: 05/29/2019] [Indexed: 01/01/2023] Open
Abstract
In eukaryotic genomes, heterochromatin is targeted by RNAi machinery and/or by pathways requiring RNA elimination and transcription termination factors. However, a direct connection between termination machinery and RNA polymerase II (RNAPII) transcriptional activity at heterochromatic loci has remained elusive. Here, we show that, in fission yeast, the conserved cleavage and polyadenylation factor (CPF) is a key component involved in RNAi-independent assembly of constitutive and facultative heterochromatin domains and that CPF is broadly required to silence genes regulated by Clr4SUV39H. Remarkably, CPF is recruited to non-canonical termination sites within the body of genes by the YTH family RNA-binding protein Mmi1 and is required for RNAPII transcription termination and facultative heterochromatin assembly. CPF loading by Mmi1 also promotes the selective termination of long non-coding RNAs that regulate gene expression in cis. These analyses delineate a mechanism in which CPF loaded onto non-canonical termination sites specifies targets of heterochromatin assembly and gene silencing.
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Affiliation(s)
- Tommy V Vo
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Jothy Dhakshnamoorthy
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Madeline Larkin
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Martin Zofall
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Gobi Thillainadesan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Vanivilasini Balachandran
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Sahana Holla
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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25
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Kieft R, Zhang Y, Marand AP, Moran JD, Bridger R, Wells L, Schmitz RJ, Sabatini R. Identification of a novel base J binding protein complex involved in RNA polymerase II transcription termination in trypanosomes. PLoS Genet 2020; 16:e1008390. [PMID: 32084124 PMCID: PMC7055916 DOI: 10.1371/journal.pgen.1008390] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 03/04/2020] [Accepted: 01/08/2020] [Indexed: 11/18/2022] Open
Abstract
Base J, β-D-glucosyl-hydroxymethyluracil, is a modification of thymine DNA base involved in RNA Polymerase (Pol) II transcription termination in kinetoplastid protozoa. Little is understood regarding how specific thymine residues are targeted for J-modification or the mechanism of J regulated transcription termination. To identify proteins involved in J-synthesis, we expressed a tagged version of the J-glucosyltransferase (JGT) in Leishmania tarentolae, and identified four co-purified proteins by mass spectrometry: protein phosphatase (PP1), a homolog of Wdr82, a potential PP1 regulatory protein (PNUTS) and a protein containing a J-DNA binding domain (named JBP3). Gel shift studies indicate JBP3 is a J-DNA binding protein. Reciprocal tagging, co-IP and sucrose gradient analyses indicate PP1, JGT, JBP3, Wdr82 and PNUTS form a multimeric complex in kinetoplastids, similar to the mammalian PTW/PP1 complex involved in transcription termination via PP1 mediated dephosphorylation of Pol II. Using RNAi and analysis of Pol II termination by RNA-seq and RT-PCR, we demonstrate that ablation of PNUTS, JBP3 and Wdr82 lead to defects in Pol II termination at the 3'-end of polycistronic gene arrays in Trypanosoma brucei. Mutants also contain increased antisense RNA levels upstream of transcription start sites, suggesting an additional role of the complex in regulating termination of bi-directional transcription. In addition, PNUTS loss causes derepression of silent Variant Surface Glycoprotein genes involved in host immune evasion. Our results suggest a novel mechanistic link between base J and Pol II polycistronic transcription termination in kinetoplastids.
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Affiliation(s)
- Rudo Kieft
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Yang Zhang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Alexandre P. Marand
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Jose Dagoberto Moran
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Robert Bridger
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Lance Wells
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Robert J. Schmitz
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Robert Sabatini
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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26
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Control of RNA Pol II Speed by PNUTS-PP1 and Spt5 Dephosphorylation Facilitates Termination by a "Sitting Duck Torpedo" Mechanism. Mol Cell 2019; 76:896-908.e4. [PMID: 31677974 DOI: 10.1016/j.molcel.2019.09.031] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/14/2019] [Accepted: 09/24/2019] [Indexed: 12/11/2022]
Abstract
Control of transcription speed, which influences many co-transcriptional processes, is poorly understood. We report that PNUTS-PP1 phosphatase is a negative regulator of RNA polymerase II (Pol II) elongation rate. The PNUTS W401A mutation, which disrupts PP1 binding, causes genome-wide acceleration of transcription associated with hyper-phosphorylation of the Spt5 elongation factor. Immediately downstream of poly(A) sites, Pol II decelerates from >2 kb/min to <1 kb/min, which correlates with Spt5 dephosphorylation. Pol II deceleration and Spt5 dephosphorylation require poly(A) site recognition and the PNUTS-PP1 complex, which is in turn necessary for transcription termination. These results lead to a model for termination, the "sitting duck torpedo" mechanism, where poly(A) site-dependent deceleration caused by PNUTS-PP1 and Spt5 dephosphorylation is required to convert Pol II into a viable target for the Xrn2 terminator exonuclease. Spt5 and its bacterial homolog NusG therefore have related functions controlling kinetic competition between RNA polymerases and the termination factors that pursue them.
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27
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Nakazawa N, Arakawa O, Yanagida M. Condensin locates at transcriptional termination sites in mitosis, possibly releasing mitotic transcripts. Open Biol 2019; 9:190125. [PMID: 31615333 PMCID: PMC6833218 DOI: 10.1098/rsob.190125] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Condensin is an essential component of chromosome dynamics, including mitotic chromosome condensation and segregation, DNA repair, and development. Genome-wide localization of condensin is known to correlate with transcriptional activity. The functional relationship between condensin accumulation and transcription sites remains unclear, however. By constructing the auxin-inducible degron strain of condensin, herein we demonstrate that condensin does not affect transcription itself. Instead, RNA processing at transcriptional termination appears to define condensin accumulation sites during mitosis, in the fission yeast Schizosaccharomyces pombe. Combining the auxin-degron strain with the nda3 β-tubulin cold-sensitive (cs) mutant enabled us to inactivate condensin in mitotically arrested cells, without releasing the cells into anaphase. Transcriptional activation and termination were not affected by condensin's degron-mediated depletion, at heat-shock inducible genes or mitotically activated genes. On the other hand, condensin accumulation sites shifted approximately 500 bp downstream in the auxin-degron of 5′-3′ exoribonuclease Dhp1, in which transcripts became aberrantly elongated, suggesting that condensin accumulates at transcriptionally terminated DNA regions. Growth defects in mutant strains of 3′-processing ribonuclease and polyA cleavage factors were additive in condensin temperature-sensitive (ts) mutants. Considering condensin's in vitro activity to form double-stranded DNAs from unwound, single-stranded DNAs or DNA-RNA hybrids, condensin-mediated processing of mitotic transcripts at the 3′-end may be a prerequisite for faithful chromosome segregation.
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Affiliation(s)
- Norihiko Nakazawa
- Okinawa Institute of Science and Technology Graduate University, G0 Cell Unit, Onna-son, Okinawa 904-0495, Japan
| | - Orie Arakawa
- Okinawa Institute of Science and Technology Graduate University, G0 Cell Unit, Onna-son, Okinawa 904-0495, Japan
| | - Mitsuhiro Yanagida
- Okinawa Institute of Science and Technology Graduate University, G0 Cell Unit, Onna-son, Okinawa 904-0495, Japan
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28
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Wang LI, Das A, McKim KS. Sister centromere fusion during meiosis I depends on maintaining cohesins and destabilizing microtubule attachments. PLoS Genet 2019; 15:e1008072. [PMID: 31150390 PMCID: PMC6581285 DOI: 10.1371/journal.pgen.1008072] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/18/2019] [Accepted: 05/16/2019] [Indexed: 11/26/2022] Open
Abstract
Sister centromere fusion is a process unique to meiosis that promotes co-orientation of the sister kinetochores, ensuring they attach to microtubules from the same pole during metaphase I. We have found that the kinetochore protein SPC105R/KNL1 and Protein Phosphatase 1 (PP1-87B) regulate sister centromere fusion in Drosophila oocytes. The analysis of these two proteins, however, has shown that two independent mechanisms maintain sister centromere fusion. Maintenance of sister centromere fusion by SPC105R depends on Separase, suggesting cohesin proteins must be maintained at the core centromeres. In contrast, maintenance of sister centromere fusion by PP1-87B does not depend on either Separase or WAPL. Instead, PP1-87B maintains sister centromeres fusion by regulating microtubule dynamics. We demonstrate that this regulation is through antagonizing Polo kinase and BubR1, two proteins known to promote stability of kinetochore-microtubule (KT-MT) attachments, suggesting that PP1-87B maintains sister centromere fusion by inhibiting stable KT-MT attachments. Surprisingly, C(3)G, the transverse element of the synaptonemal complex (SC), is also required for centromere separation in Pp1-87B RNAi oocytes. This is evidence for a functional role of centromeric SC in the meiotic divisions, that might involve regulating microtubule dynamics. Together, we propose two mechanisms maintain co-orientation in Drosophila oocytes: one involves SPC105R to protect cohesins at sister centromeres and another involves PP1-87B to regulate spindle forces at end-on attachments.
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Affiliation(s)
- Lin-Ing Wang
- Waksman Institute and Department of Genetics, Rutgers, the State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Arunika Das
- Waksman Institute and Department of Genetics, Rutgers, the State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Kim S. McKim
- Waksman Institute and Department of Genetics, Rutgers, the State University of New Jersey, Piscataway, New Jersey, United States of America
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29
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Escandell JM, Carvalho ES, Gallo-Fernandez M, Reis CC, Matmati S, Luís IM, Abreu IA, Coulon S, Ferreira MG. Ssu72 phosphatase is a conserved telomere replication terminator. EMBO J 2019; 38:embj.2018100476. [PMID: 30796050 PMCID: PMC6443209 DOI: 10.15252/embj.2018100476] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 01/21/2019] [Accepted: 01/28/2019] [Indexed: 01/31/2023] Open
Abstract
Telomeres, the protective ends of eukaryotic chromosomes, are replicated through concerted actions of conventional DNA polymerases and elongated by telomerase, but the regulation of this process is not fully understood. Telomere replication requires (Ctc1/Cdc13)‐Stn1‐Ten1, a telomeric ssDNA‐binding complex homologous to RPA. Here, we show that the evolutionarily conserved phosphatase Ssu72 is responsible for terminating the cycle of telomere replication in fission yeast. Ssu72 controls the recruitment of Stn1 to telomeres by regulating Stn1 phosphorylation at Ser74, a residue located within its conserved OB‐fold domain. Consequently, ssu72∆ mutants are defective in telomere replication and exhibit long 3′‐ssDNA overhangs, indicative of defective lagging‐strand DNA synthesis. We also show that hSSU72 regulates telomerase activation in human cells by controlling recruitment of hSTN1 to telomeres. These results reveal a previously unknown yet conserved role for the phosphatase SSU72, whereby this enzyme controls telomere homeostasis by activating lagging‐strand DNA synthesis, thus terminating the cycle of telomere replication.
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Affiliation(s)
| | | | | | - Clara C Reis
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Samah Matmati
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Inês Matias Luís
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Isabel A Abreu
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Stéphane Coulon
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Miguel Godinho Ferreira
- Instituto Gulbenkian de Ciência, Oeiras, Portugal .,Institute for Research on Cancer and Aging of Nice (IRCAN), INSERM U1081 UMR7284, CNRS, Nice, France
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30
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RNA polymerase II CTD interactome with 3' processing and termination factors in fission yeast and its impact on phosphate homeostasis. Proc Natl Acad Sci U S A 2018; 115:E10652-E10661. [PMID: 30355770 DOI: 10.1073/pnas.1810711115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The carboxy-terminal domain (CTD) code encrypted within the Y1S2P3T4S5P6S7 heptad repeats of RNA polymerase II (Pol2) is deeply rooted in eukaryal biology. Key steps to deciphering the code are identifying the events in gene expression that are governed by individual "letters" and then defining a vocabulary of multiletter "words" and their meaning. Thr4 and Ser7 exert opposite effects on the fission yeast pho1 gene, expression of which is repressed under phosphate-replete conditions by transcription of an upstream flanking long noncoding RNA (lncRNA). Here we attribute the derepression of pho1 by a CTD-S7A mutation to precocious termination of lncRNA synthesis, an effect that is erased by mutations of cleavage-polyadenylation factor (CPF) subunits Ctf1, Ssu72, Ppn1, Swd22, and Dis2 and termination factor Rhn1. By contrast, a CTD-T4A mutation hyperrepresses pho1, as do CPF subunit and Rhn1 mutations, implying that T4A reduces lncRNA termination. Moreover, CTD-T4A is synthetically lethal with ppn1∆ and swd22∆, signifying that Thr4 and the Ppn1•Swd22 module play important, functionally redundant roles in promoting Pol2 termination. We find that Ppn1 and Swd22 become essential for viability when the CTD array is curtailed and that S7A overcomes the need for Ppn1•Swd22 in the short CTD context. Mutational synergies highlight redundant essential functions of (i) Ppn1•Swd22 and Rhn1, (ii) Ppn1•Swd22 and Ctf1, and (iii) Ssu72 and Dis2 phosphatases. CTD alleles Y1F, S2A, and T4A have overlapping synthetic lethalities with ppn1∆ and swd22∆, suggesting that Tyr1-Ser2-Thr4 form a three-letter CTD word that abets termination, with Rhn1 being a likely "reader" of this word.
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31
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Kecman T, Kuś K, Heo DH, Duckett K, Birot A, Liberatori S, Mohammed S, Geis-Asteggiante L, Robinson CV, Vasiljeva L. Elongation/Termination Factor Exchange Mediated by PP1 Phosphatase Orchestrates Transcription Termination. Cell Rep 2018; 25:259-269.e5. [PMID: 30282034 PMCID: PMC6180485 DOI: 10.1016/j.celrep.2018.09.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/27/2018] [Accepted: 09/04/2018] [Indexed: 11/20/2022] Open
Abstract
Termination of RNA polymerase II (Pol II) transcription is a key step that is important for 3' end formation of functional mRNA, mRNA release, and Pol II recycling. Even so, the underlying termination mechanism is not yet understood. Here, we demonstrate that the conserved and essential termination factor Seb1 is found on Pol II near the end of the RNA exit channel and the Rpb4/7 stalk. Furthermore, the Seb1 interaction surface with Pol II largely overlaps with that of the elongation factor Spt5. Notably, Seb1 co-transcriptional recruitment is dependent on Spt5 dephosphorylation by the conserved PP1 phosphatase Dis2, which also dephosphorylates threonine 4 within the Pol II heptad repeated C-terminal domain. We propose that Dis2 orchestrates the transition from elongation to termination phase during the transcription cycle by mediating elongation to termination factor exchange and dephosphorylation of Pol II C-terminal domain.
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Affiliation(s)
- Tea Kecman
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Krzysztof Kuś
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Dong-Hyuk Heo
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Katie Duckett
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Adrien Birot
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | - Shabaz Mohammed
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Department of Chemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | - Carol V Robinson
- Department of Chemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Lidia Vasiljeva
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
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32
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Hocquet C, Robellet X, Modolo L, Sun XM, Burny C, Cuylen-Haering S, Toselli E, Clauder-Münster S, Steinmetz L, Haering CH, Marguerat S, Bernard P. Condensin controls cellular RNA levels through the accurate segregation of chromosomes instead of directly regulating transcription. eLife 2018; 7:38517. [PMID: 30230473 PMCID: PMC6173581 DOI: 10.7554/elife.38517] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 09/18/2018] [Indexed: 12/15/2022] Open
Abstract
Condensins are genome organisers that shape chromosomes and promote their accurate transmission. Several studies have also implicated condensins in gene expression, although any mechanisms have remained enigmatic. Here, we report on the role of condensin in gene expression in fission and budding yeasts. In contrast to previous studies, we provide compelling evidence that condensin plays no direct role in the maintenance of the transcriptome, neither during interphase nor during mitosis. We further show that the changes in gene expression in post-mitotic fission yeast cells that result from condensin inactivation are largely a consequence of chromosome missegregation during anaphase, which notably depletes the RNA-exosome from daughter cells. Crucially, preventing karyotype abnormalities in daughter cells restores a normal transcriptome despite condensin inactivation. Thus, chromosome instability, rather than a direct role of condensin in the transcription process, changes gene expression. This knowledge challenges the concept of gene regulation by canonical condensin complexes.
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Affiliation(s)
- Clémence Hocquet
- CNRS Laboratory of Biology and Modelling of the Cell, Lyon, France.,Université de Lyon, ENSL, UCBL, Lyon, France
| | - Xavier Robellet
- CNRS Laboratory of Biology and Modelling of the Cell, Lyon, France.,Université de Lyon, ENSL, UCBL, Lyon, France
| | - Laurent Modolo
- CNRS Laboratory of Biology and Modelling of the Cell, Lyon, France.,Université de Lyon, ENSL, UCBL, Lyon, France
| | - Xi-Ming Sun
- MRC London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Claire Burny
- CNRS Laboratory of Biology and Modelling of the Cell, Lyon, France.,Université de Lyon, ENSL, UCBL, Lyon, France
| | - Sara Cuylen-Haering
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Esther Toselli
- CNRS Laboratory of Biology and Modelling of the Cell, Lyon, France.,Université de Lyon, ENSL, UCBL, Lyon, France
| | | | - Lars Steinmetz
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Christian H Haering
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Samuel Marguerat
- MRC London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Pascal Bernard
- CNRS Laboratory of Biology and Modelling of the Cell, Lyon, France.,Université de Lyon, ENSL, UCBL, Lyon, France
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33
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Parua PK, Booth GT, Sansó M, Benjamin B, Tanny JC, Lis JT, Fisher RP. A Cdk9-PP1 switch regulates the elongation-termination transition of RNA polymerase II. Nature 2018; 558:460-464. [PMID: 29899453 PMCID: PMC6021199 DOI: 10.1038/s41586-018-0214-z] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 04/17/2018] [Indexed: 11/09/2022]
Abstract
The end of the RNA polymerase II (Pol II) transcription cycle is strictly regulated to prevent interference between neighbouring genes and to safeguard transcriptome integrity 1 . The accumulation of Pol II downstream of the cleavage and polyadenylation signal can facilitate the recruitment of factors involved in mRNA 3'-end formation and termination 2 , but how this sequence is initiated remains unclear. In a chemical-genetic screen, human protein phosphatase 1 (PP1) isoforms were identified as substrates of positive transcription elongation factor b (P-TEFb), also known as the cyclin-dependent kinase 9 (Cdk9)-cyclin T1 (CycT1) complex 3 . Here we show that Cdk9 and PP1 govern phosphorylation of the conserved elongation factor Spt5 in the fission yeast Schizosaccharomyces pombe. Cdk9 phosphorylates both Spt5 and a negative regulatory site on the PP1 isoform Dis2 4 . Sites targeted by Cdk9 in the Spt5 carboxy-terminal domain can be dephosphorylated by Dis2 in vitro, and dis2 mutations retard Spt5 dephosphorylation after inhibition of Cdk9 in vivo. Chromatin immunoprecipitation and sequencing analysis indicates that Spt5 is dephosphorylated as transcription complexes traverse the cleavage and polyadenylation signal, concomitant with the accumulation of Pol II phosphorylated at residue Ser2 of the carboxy-terminal domain consensus heptad repeat 5 . A conditionally lethal Dis2-inactivating mutation attenuates the drop in Spt5 phosphorylation on chromatin, promotes transcription beyond the normal termination zone (as detected by precision run-on transcription and sequencing 6 ) and is genetically suppressed by the ablation of Cdk9 target sites in Spt5. These results suggest that the transition of Pol II from elongation to termination coincides with a Dis2-dependent reversal of Cdk9 signalling-a switch that is analogous to a Cdk1-PP1 circuit that controls mitotic progression 4 .
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Affiliation(s)
- Pabitra K Parua
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Gregory T Booth
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Miriam Sansó
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Cancer Genomics Group, Vall d'Hebron Institute of Oncology, Barcelona, Spain
| | - Bradley Benjamin
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jason C Tanny
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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34
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Hartono SR, Malapert A, Legros P, Bernard P, Chédin F, Vanoosthuyse V. The Affinity of the S9.6 Antibody for Double-Stranded RNAs Impacts the Accurate Mapping of R-Loops in Fission Yeast. J Mol Biol 2017; 430:272-284. [PMID: 29289567 DOI: 10.1016/j.jmb.2017.12.016] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 12/25/2022]
Abstract
R-loops, which result from the formation of stable DNA:RNA hybrids, can both threaten genome integrity and act as physiological regulators of gene expression and chromatin patterning. To characterize R-loops in fission yeast, we used the S9.6 antibody-based DRIPc-seq method to sequence the RNA strand of R-loops and obtain strand-specific R-loop maps at near nucleotide resolution. Surprisingly, preliminary DRIPc-seq experiments identified mostly RNase H-resistant but exosome-sensitive RNAs that mapped to both DNA strands and resembled RNA:RNA hybrids (dsRNAs), suggesting that dsRNAs form widely in fission yeast. We confirmed in vitro that S9.6 can immuno-precipitate dsRNAs and provide evidence that dsRNAs can interfere with its binding to R-loops. dsRNA elimination by RNase III treatment prior to DRIPc-seq allowed the genome-wide and strand-specific identification of genuine R-loops that responded in vivo to RNase H levels and displayed classical features associated with R-loop formation. We also found that most transcripts whose levels were altered by in vivo manipulation of RNase H levels did not form detectable R-loops, suggesting that prolonged manipulation of R-loop levels could indirectly alter the transcriptome. We discuss the implications of our work in the design of experimental strategies to probe R-loop functions.
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Affiliation(s)
- Stella R Hartono
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA, 95616, United States; Integrative Genetics and Genomics Graduate Group, University of California, Davis, CA, 95616, United States
| | - Amélie Malapert
- UMR5239 CNRS/Université de Lyon/ENS-Lyon, 46 Allée d'Italie, 69007 Lyon, France
| | - Pénélope Legros
- UMR5239 CNRS/Université de Lyon/ENS-Lyon, 46 Allée d'Italie, 69007 Lyon, France
| | - Pascal Bernard
- UMR5239 CNRS/Université de Lyon/ENS-Lyon, 46 Allée d'Italie, 69007 Lyon, France
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA, 95616, United States
| | - Vincent Vanoosthuyse
- UMR5239 CNRS/Université de Lyon/ENS-Lyon, 46 Allée d'Italie, 69007 Lyon, France.
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35
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Lemay JF, Marguerat S, Larochelle M, Liu X, van Nues R, Hunyadkürti J, Hoque M, Tian B, Granneman S, Bähler J, Bachand F. The Nrd1-like protein Seb1 coordinates cotranscriptional 3' end processing and polyadenylation site selection. Genes Dev 2017; 30:1558-72. [PMID: 27401558 PMCID: PMC4949328 DOI: 10.1101/gad.280222.116] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/10/2016] [Indexed: 11/25/2022]
Abstract
Termination of RNA polymerase II (RNAPII) transcription is associated with RNA 3' end formation. For coding genes, termination is initiated by the cleavage/polyadenylation machinery. In contrast, a majority of noncoding transcription events in Saccharomyces cerevisiae does not rely on RNA cleavage for termination but instead terminates via a pathway that requires the Nrd1-Nab3-Sen1 (NNS) complex. Here we show that the Schizosaccharomyces pombe ortholog of Nrd1, Seb1, does not function in NNS-like termination but promotes polyadenylation site selection of coding and noncoding genes. We found that Seb1 associates with 3' end processing factors, is enriched at the 3' end of genes, and binds RNA motifs downstream from cleavage sites. Importantly, a deficiency in Seb1 resulted in widespread changes in 3' untranslated region (UTR) length as a consequence of increased alternative polyadenylation. Given that Seb1 levels affected the recruitment of conserved 3' end processing factors, our findings indicate that the conserved RNA-binding protein Seb1 cotranscriptionally controls alternative polyadenylation.
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Affiliation(s)
- Jean-François Lemay
- RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada
| | - Samuel Marguerat
- MRC Clinical Sciences Centre (CSC), London W12 0NN, United Kingdom; Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Marc Larochelle
- RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada
| | - Xiaochuan Liu
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA; Rutgers Cancer Institute of New Jersey, Newark, New Jersey 08903, USA
| | - Rob van Nues
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Judit Hunyadkürti
- RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada
| | - Mainul Hoque
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA; Rutgers Cancer Institute of New Jersey, Newark, New Jersey 08903, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA; Rutgers Cancer Institute of New Jersey, Newark, New Jersey 08903, USA
| | - Sander Granneman
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom; Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Jürg Bähler
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
| | - François Bachand
- RNA Group, Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada
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36
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The loading of condensin in the context of chromatin. Curr Genet 2016; 63:577-589. [PMID: 27909798 DOI: 10.1007/s00294-016-0669-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 11/24/2016] [Accepted: 11/25/2016] [Indexed: 12/23/2022]
Abstract
The packaging of DNA into chromosomes is a ubiquitous process that enables living organisms to structure and transmit their genome accurately through cell divisions. In the three kingdoms of life, the architecture and dynamics of chromosomes rely upon ring-shaped SMC (Structural Maintenance of Chromosomes) condensin complexes. To understand how condensin rings organize chromosomes, it is essential to decipher how they associate with chromatin filaments. Here, we use recent evidence to discuss the role played by nucleosomes and transcription factors in the loading of condensin at transcribed genes. We propose a model whereby cis-acting features nestled in the promoters of active genes synergistically attract condensin rings and promote their association with DNA.
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Toselli-Mollereau E, Robellet X, Fauque L, Lemaire S, Schiklenk C, Klein C, Hocquet C, Legros P, N'Guyen L, Mouillard L, Chautard E, Auboeuf D, Haering CH, Bernard P. Nucleosome eviction in mitosis assists condensin loading and chromosome condensation. EMBO J 2016; 35:1565-81. [PMID: 27266525 DOI: 10.15252/embj.201592849] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 05/05/2016] [Indexed: 12/15/2022] Open
Abstract
Condensins associate with DNA and shape mitotic chromosomes. Condensins are enriched nearby highly expressed genes during mitosis, but how this binding is achieved and what features associated with transcription attract condensins remain unclear. Here, we report that condensin accumulates at or in the immediate vicinity of nucleosome-depleted regions during fission yeast mitosis. Two transcriptional coactivators, the Gcn5 histone acetyltransferase and the RSC chromatin-remodelling complex, bind to promoters adjoining condensin-binding sites and locally evict nucleosomes to facilitate condensin binding and allow efficient mitotic chromosome condensation. The function of Gcn5 is closely linked to condensin positioning, since neither the localization of topoisomerase II nor that of the cohesin loader Mis4 is altered in gcn5 mutant cells. We propose that nucleosomes act as a barrier for the initial binding of condensin and that nucleosome-depleted regions formed at highly expressed genes by transcriptional coactivators constitute access points into chromosomes where condensin binds free genomic DNA.
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Affiliation(s)
- Esther Toselli-Mollereau
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Xavier Robellet
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Lydia Fauque
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Sébastien Lemaire
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | | | - Carlo Klein
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
| | - Clémence Hocquet
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Pénélope Legros
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Lia N'Guyen
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Léo Mouillard
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Emilie Chautard
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | - Didier Auboeuf
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
| | | | - Pascal Bernard
- Laboratory of Biology and Modelling of the Cell, Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
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38
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Interconnections Between RNA-Processing Pathways Revealed by a Sequencing-Based Genetic Screen for Pre-mRNA Splicing Mutants in Fission Yeast. G3-GENES GENOMES GENETICS 2016; 6:1513-23. [PMID: 27172183 PMCID: PMC4889648 DOI: 10.1534/g3.116.027508] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pre-mRNA splicing is an essential component of eukaryotic gene expression and is highly conserved from unicellular yeasts to humans. Here, we present the development and implementation of a sequencing-based reverse genetic screen designed to identify nonessential genes that impact pre-mRNA splicing in the fission yeast Schizosaccharomyces pombe, an organism that shares many of the complex features of splicing in higher eukaryotes. Using a custom-designed barcoding scheme, we simultaneously queried ∼3000 mutant strains for their impact on the splicing efficiency of two endogenous pre-mRNAs. A total of 61 nonessential genes were identified whose deletions resulted in defects in pre-mRNA splicing; enriched among these were factors encoding known or predicted components of the spliceosome. Included among the candidates identified here are genes with well-characterized roles in other RNA-processing pathways, including heterochromatic silencing and 3ʹ end processing. Splicing-sensitive microarrays confirm broad splicing defects for many of these factors, revealing novel functional connections between these pathways.
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39
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Sansó M, Levin RS, Lipp JJ, Wang VYF, Greifenberg AK, Quezada EM, Ali A, Ghosh A, Larochelle S, Rana TM, Geyer M, Tong L, Shokat KM, Fisher RP. P-TEFb regulation of transcription termination factor Xrn2 revealed by a chemical genetic screen for Cdk9 substrates. Genes Dev 2016; 30:117-31. [PMID: 26728557 PMCID: PMC4701974 DOI: 10.1101/gad.269589.115] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sansó et al. identified ∼100 putative substrates of human positive transcription elongation factor b (P-TEFb), which were enriched for proteins implicated in transcription and RNA catabolism. Among the RNA processing factors phosphorylated by Cdk9 was the 5′-to-3′ “torpedo” exoribonuclease Xrn2, required in transcription termination by Pol II. The transcription cycle of RNA polymerase II (Pol II) is regulated at discrete transition points by cyclin-dependent kinases (CDKs). Positive transcription elongation factor b (P-TEFb), a complex of Cdk9 and cyclin T1, promotes release of paused Pol II into elongation, but the precise mechanisms and targets of Cdk9 action remain largely unknown. Here, by a chemical genetic strategy, we identified ∼100 putative substrates of human P-TEFb, which were enriched for proteins implicated in transcription and RNA catabolism. Among the RNA processing factors phosphorylated by Cdk9 was the 5′-to-3′ “torpedo” exoribonuclease Xrn2, required in transcription termination by Pol II, which we validated as a bona fide P-TEFb substrate in vivo and in vitro. Phosphorylation by Cdk9 or phosphomimetic substitution of its target residue, Thr439, enhanced enzymatic activity of Xrn2 on synthetic substrates in vitro. Conversely, inhibition or depletion of Cdk9 or mutation of Xrn2-Thr439 to a nonphosphorylatable Ala residue caused phenotypes consistent with inefficient termination in human cells: impaired Xrn2 chromatin localization and increased readthrough transcription of endogenous genes. Therefore, in addition to its role in elongation, P-TEFb regulates termination by promoting chromatin recruitment and activation of a cotranscriptional RNA processing enzyme, Xrn2.
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Affiliation(s)
- Miriam Sansó
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Rebecca S Levin
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Jesse J Lipp
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Vivien Ya-Fan Wang
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Ann Katrin Greifenberg
- Department of Structural Immunology, Institute of Innate Immunity, University of Bonn, 53127 Bonn, Germany
| | - Elizabeth M Quezada
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Akbar Ali
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Animesh Ghosh
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Stéphane Larochelle
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Tariq M Rana
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA
| | - Matthias Geyer
- Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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40
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Austenaa L, Barozzi I, Simonatto M, Masella S, Della Chiara G, Ghisletti S, Curina A, de Wit E, Bouwman B, de Pretis S, Piccolo V, Termanini A, Prosperini E, Pelizzola M, de Laat W, Natoli G. Transcription of Mammalian cis-Regulatory Elements Is Restrained by Actively Enforced Early Termination. Mol Cell 2015; 60:460-74. [DOI: 10.1016/j.molcel.2015.09.018] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 08/13/2015] [Accepted: 09/17/2015] [Indexed: 12/12/2022]
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41
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Bernard P, Vanoosthuyse V. Does transcription play a role in creating a condensin binding site? Transcription 2015; 6:12-6. [PMID: 25634470 DOI: 10.1080/21541264.2015.1012980] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The highly conserved condensin complex is essential for the condensation and integrity of chromosomes through cell division. Published data argue that high levels of transcription contribute to specify some condensin-binding sites on chromosomes but the exact role of transcription in this process remains elusive. Here we discuss our recent data addressing the role of transcription in establishing a condensin-binding site.
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Affiliation(s)
- Pascal Bernard
- a CNRS, Université Lyon 01, UMR5239, LBMC; Ecole Normale Supérieure de Lyon , Lyon , France
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42
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Legros P, Malapert A, Niinuma S, Bernard P, Vanoosthuyse V. RNA processing factors Swd2.2 and Sen1 antagonize RNA Pol III-dependent transcription and the localization of condensin at Pol III genes. PLoS Genet 2014; 10:e1004794. [PMID: 25392932 PMCID: PMC4230746 DOI: 10.1371/journal.pgen.1004794] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 10/02/2014] [Indexed: 11/19/2022] Open
Abstract
Condensin-mediated chromosome condensation is essential for genome stability upon cell division. Genetic studies have indicated that the association of condensin with chromatin is intimately linked to gene transcription, but what transcription-associated feature(s) direct(s) the accumulation of condensin remains unclear. Here we show in fission yeast that condensin becomes strikingly enriched at RNA Pol III-transcribed genes when Swd2.2 and Sen1, two factors involved in the transcription process, are simultaneously deleted. Sen1 is an ATP-dependent helicase whose orthologue in Saccharomyces cerevisiae contributes both to terminate transcription of some RNA Pol II transcripts and to antagonize the formation of DNA:RNA hybrids in the genome. Using two independent mapping techniques, we show that DNA:RNA hybrids form in abundance at Pol III-transcribed genes in fission yeast but we demonstrate that they are unlikely to faciliate the recruitment of condensin. Instead, we show that Sen1 forms a stable and abundant complex with RNA Pol III and that Swd2.2 and Sen1 antagonize both the interaction of RNA Pol III with chromatin and RNA Pol III-dependent transcription. When Swd2.2 and Sen1 are lacking, the increased concentration of RNA Pol III and condensin at Pol III-transcribed genes is accompanied by the accumulation of topoisomerase I and II and by local nucleosome depletion, suggesting that Pol III-transcribed genes suffer topological stress. We provide evidence that this topological stress contributes to recruit and/or stabilize condensin at Pol III-transcribed genes in the absence of Swd2.2 and Sen1. Our data challenge the idea that a processive RNA polymerase hinders the binding of condensin and suggest that transcription-associated topological stress could in some circumstances facilitate the association of condensin. Failure to condense chromosomes prior to anaphase onset can lead to genome instability. The evolutionary-conserved condensin complex drives chromosome condensation, probably by changing the topology of chromatin around its binding sites. Condensin localizes to regions of high transcription, suggesting that some transcription-associated feature(s) direct its association with chromatin. Here we considered that transcription-dependent DNA:RNA hybrids or topological stress could be involved in recruiting condensin. Our data show that condensin is indeed enriched at regions accumulating DNA:RNA hybrids but that they are not involved in its recruitment. Rather, we identify a mutant combination where increased transcription by RNA Pol III is associated locally with stronger topological stress. Strikingly the localization of condensin is dramatically enhanced at the same loci and we show that topological stress contributes to this enhanced association. Our data strengthen the idea that transcription creates the environment necessary to recruit condensin in mitosis.
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Affiliation(s)
- Pénélope Legros
- CNRS, Université Lyon 01, UMR5239, LBMC; Ecole Normale Supérieure de Lyon, Lyon, France.
| | - Amélie Malapert
- CNRS, Université Lyon 01, UMR5239, LBMC; Ecole Normale Supérieure de Lyon, Lyon, France.
| | - Sho Niinuma
- CNRS, Université Lyon 01, UMR5239, LBMC; Ecole Normale Supérieure de Lyon, Lyon, France.
| | - Pascal Bernard
- CNRS, Université Lyon 01, UMR5239, LBMC; Ecole Normale Supérieure de Lyon, Lyon, France.
| | - Vincent Vanoosthuyse
- CNRS, Université Lyon 01, UMR5239, LBMC; Ecole Normale Supérieure de Lyon, Lyon, France.
- * E-mail:
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