Project description:The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAP II) consists of repeated YSPTSPS heptapeptides and connects transcription with cotranscriptional events. Threonine-4 (Thr4) of the CTD repeats has been shown to function in histone mRNA 3'-end processing in chicken cells and in transcriptional elongation in human cells. Here, we demonstrate that, in budding yeast, Thr4, although dispensable for growth in rich media, is essential in phosphate-depleted or galactose-containing media. Thr4 is required to maintain repression of phosphate-regulated (PHO) genes under normal growth conditions and for full induction of PHO5 and the galactose-induced GAL1 and GAL7 genes. We identify genetic links between Thr4 and the histone variant Htz1 and show that Thr4, as well as the Ino80 chromatin remodeler, is required for activation-associated eviction of Htz1 specifically from promoters of the Thr4-dependent genes. Our study uncovers a connection between transcription and chromatin remodeling linked by Thr4 of the CTD. RNA-seq of wild type and T4V mutant of budding yeast RNAP II CTD in duplicates
Project description:The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAP II) consists of repeated YSPTSPS heptapeptides and connects transcription with cotranscriptional events. Threonine-4 (Thr4) of the CTD repeats has been shown to function in histone mRNA 3'-end processing in chicken cells and in transcriptional elongation in human cells. Here, we demonstrate that, in budding yeast, Thr4, although dispensable for growth in rich media, is essential in phosphate-depleted or galactose-containing media. Thr4 is required to maintain repression of phosphate-regulated (PHO) genes under normal growth conditions and for full induction of PHO5 and the galactose-induced GAL1 and GAL7 genes. We identify genetic links between Thr4 and the histone variant Htz1 and show that Thr4, as well as the Ino80 chromatin remodeler, is required for activation-associated eviction of Htz1 specifically from promoters of the Thr4-dependent genes. Our study uncovers a connection between transcription and chromatin remodeling linked by Thr4 of the CTD.
Project description:Eukaryotic gene expression requires that RNA Polymerase II (RNAP II) gain access to DNA in the context of chromatin. The C-terminal domain (CTD) of RNAP II recruits chromatin modifying enzymes to promoters, allowing for transcription initiation or repression. Specific CTD phosphorylation marks facilitate recruitment of chromatin modifiers, transcriptional regulators, and RNA processing factors during the transcription cycle. However, the readable code for recruiting such factors is still not fully defined and how CTD modifications affect related families of genes or regional gene expression is not well understood. Here we examine the effects of manipulating the Y1S2P3T4S5P6S7 heptapeptide repeat of the CTD of RNAP II in Schizosaccharomyces pombe by substituting non-phosphorylatable alanines for Ser2 and/or Ser7 and the phosphomimetic glutamic acid for Ser7. Global gene expression analyses were conducted using splicing-sensitive microarrays and validated via RT-qPCR. The CTD mutations did not affect pre-mRNA splicing or snRNA levels. Rather, the data revealed upregulation of subtelomeric genes and alteration of the repressive histone H3 lysine 9 methylation (HeK9me) landscape. The data further indicate that H3K9me and expression status are not fully correlated, suggestive of CTD-dependent subtelomeric repression mechansims that act independently of H3K9me levels.
Project description:In yeast and other eukaryotes, the histone methyltransferase Set1 mediates methylation of lysine 4 on histone H3 (H3K4me). This modification marks the 5' end of transcribed genes in a 5' to 3' tri- to di- to monomethyl gradient, and promotes association of chromatin remodeling enzymes that regulate transcription. In a screen to identify factors that control the distinct H3K4 methylation states, we identified Ctk1, the serine 2 C-terminal domain (CTD) kinase for RNA polymerase II (RNAP II). We found that CTK1 deletion nearly abolished H3K4 monomethylation, yet caused a significant increase in H3K4 di- and trimethylation. Both on individual genes and genome-wide, the loss of CTK1 disrupted the H3K4 methylation patterns normally observed. H3K4me2 and H3K4me3 spread 3' into the body of genes, while H3K4 monomethylation was diminished. These effects were dependent on the catalytic activity of Ctk1, but are independent of Set2-mediated H3K36 methylation. Furthermore, these effects are not due to spurious transcription initiation in the body of genes, changes in RNAP II occupancy, changes in serine 5 CTD phosphorylation patterns, or to ‘transcriptional stress’. These data show that Ctk1 acts to restrict the spread of H3K4 methylation through a mechanism that is independent of a general transcription defect. The evidence presented indicates that Ctk1 controls the maintenance of suppressive chromatin in the coding regions of genes by both promoting H3K36 methylation, which leads to histone hypoacetylation, and by preventing the 3' spread of H3K4 trimethylation, a mark associated with chromatin remodeling at the 5' end of genes. Keywords: ChIP-chip
Project description:Eukaryotic gene expression requires that RNA Polymerase II (RNAP II) gain access to DNA in the context of chromatin. The C-terminal domain (CTD) of RNAP II recruits chromatin modifying enzymes to promoters, allowing for transcription initiation or repression. Specific CTD phosphorylation marks facilitate recruitment of chromatin modifiers, transcriptional regulators, and RNA processing factors during the transcription cycle. However, the readable code for recruiting such factors is still not fully defined and how CTD modifications affect related families of genes or regional gene expression is not well understood. Here we examine the effects of manipulating the Y1S2P3T4S5P6S7 heptapeptide repeat of the CTD of RNAP II in Schizosaccharomyces pombe by substituting non-phosphorylatable alanines for Ser2 and/or Ser7 and the phosphomimetic glutamic acid for Ser7. Global gene expression analyses were conducted using splicing-sensitive microarrays and validated via RT-qPCR. The CTD mutations did not affect pre-mRNA splicing or snRNA levels. Rather, the data revealed upregulation of subtelomeric genes and alteration of the repressive histone H3 lysine 9 methylation (HeK9me) landscape. The data further indicate that H3K9me and expression status are not fully correlated, suggestive of CTD-dependent subtelomeric repression mechansims that act independently of H3K9me levels. Splicing sensitive S. pombe microarrays (Agilent-027365) were used to compare the splicing and expression profile of four mutant strains relative to WT control with 3-5 biological replicates and dye flipped samples
Project description:The protein Seb1 from fission yeast contains a conserved CTD-interacting domain (CID) with which it can bind to phosphorylated forms of the Pol II C-terminal domain (CTD) during active transcription. It mainly interacts with Ser2P-CTD but also with Ser5P-CTD. Here, we show the recruitment profile of the protein to chromatin using ChIP-Seq which is mediated mainly via binding to the Pol II-CTD. In addition, it can also interact with nascent RNA via its RNA recognition motif (RRM) domain.
Project description:ChIP-chip was performed to identify the genomic binding locations for the termination factors Nrd1, and Rtt103, and for RNA polymerase (Pol) II phosphorylated at the tyrosine 1 and threonine 4 position of its C-terminal domain (CTD). In different phases of the transcription cycle, Pol II recruits different factors via its CTD, which consists of heptapeptide repeats with the sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. Here we show that the CTD of transcribing yeast Pol II is phosphorylated at Tyr1, and that this impairs recruitment of termination factors. Tyr1 phosphorylation levels rise downstream of the transcription start site (TSS), and decrease before the polyadenylation (pA) site. Tyr1-phosphorylated gene bodies are depleted of CTD-binding termination factors Nrd1, Pcf11, and Rtt103. Tyr1 phosphorylation blocks CTD binding by these termination factors, but stimulates binding of elongation factor Spt6. These results show that CTD modifications can not only stimulate but also block factor recruitment, and lead to an extended CTD code for transcription cycle coordination.
Project description:The C-terminal domain (CTD) of the largest subunit in DNA-dependent RNA polymerase II (RNAP II) is essential for mRNA syntheses, coordinating an astounding array of protein-protein interactions. In yeast, mutations that separate established functional units of the CTD result in pleiotrophic effects, producing slow growth phenotypes and the accumulation of abnormally large cells. In general, the downstream pathways for such CTD related phenotypes are uncharacterized and probably highly complex. We also observed that a sizeable fraction of CTD mutants retain multiple buds on parent cells and are elongated relative to wild-type yeast. FACScan analyses revealed a trend toward increased DNA content over multiple rounds of growth, indicating that insertions into the normal tandemly repeated CTD result in aneuploidy. To begin to address the role of the CTD in such complex changes in cell structure and behavior, we applied an integrated approach using the Saccharomyces cerevisiae Genome Database (SGD) and microarray data. We were able to identify candidate genetic networks that could explain chromosome missegregation and related phenotypic traits in CTD mutants. These networks provide links between CTD-associated proteins and kinetochore function, control of cell cycle checkpoint mechanisms, and expression of cell wall and membrane components.
Project description:Cyclin dependent kinases activation and RNA polymerase II transcription are linked by the Cdk7 kinase that phosphorylates Cdks as a trimeric CAK complex, and serine 5 within the PolII C-terminal domain (CTD) as TFIIH bound CAK. However, the physiological importance of integrating these processes is not understood. Beside the Cdk7 ortholog Mcs6, fission yeast possesses a second CAK, Csk1. Both enzymes were proposed to act redundantly to activate Cdc2. Using an improved analogue sensitive Mcs6-as kinase, we show that Csk1 is not a relevant CAK for Cdc2. Further analyses revealed that Csk1 lacks a 20 amino acid sequence required for its budding yeast counterpart, Cak1, to bind Cdc2. Transcriptome profiling of the Mcs6-as mutant in the presence or absence of the budding yeast Cak1 kinase, in order to uncouple the CTD kinase and CAK activities of Mcs6, revealed an unanticipated role of the CAK branch in the transcriptional control of the cluster of genes implicated in ribosome biogenesis and cell growth. The analysis of a Cdc2 CAK site mutant confirmed these data. Our data show that the Cdk7 kinase modulates transcription through both its well-described RNA Polymerase II CTD kinase activity, but also through the Cdc2 activating kinase activity.
Project description:The modification of Ser 5 is important for the relocalization of RNAP II upon NaCl stress. The CTD14 strains harbors a plasmid expressing RPB1 with 14 wild-type CTD repeats. The 5A strain carries a plasmid expressing a chimeric RPB1 in which the CTD was composed of 5 repeats of CTD-serine 5 substituted with alanine followed by 7 wild-type-sequenced repeats.