Project description:Spt6 is a multifunctional histone chaperone involved in the maintenance of chromatin structure during elongation by RNA polymerase II (Pol II). Spt6 has a tandem SH2 (tSH2) domain within its C-terminus that recognizes Pol II CTD peptides phosphorylated on Ser2, Ser5 or Try1 in vitro. Deleting the tSH2 domain, however, only has a partial effect on Spt6 occupancy in vivo, suggesting that more complex mechanisms are involved in the Spt6 recruitment. Our results show that the Ser2 kinases Bur1 and Ctk1, but not the Ser5 kinase Kin28, cooperate in recruiting Spt6, genome-wide. Interestingly, the Ser2 kinases promote the association of Spt6 in early transcribed regions and not toward the 3' end of genes, where phosphorylated Ser2 reaches its maximum level. Additionally, our results uncover an unexpected role for histone deacetylases (Rpd3 and Hos2) in promoting Spt6 interaction with elongating Pol II. Finally, our data suggest that phosphorylation of the Pol II CTD on Tyr1 promotes the association of Spt6 with the 3' end of transcribed genes, independently of Ser2 phosphorylation. Collectively, our results show that a complex network of interactions, involving the Spt6 tSH2 domain, CTD phosphorylation and histone deacetylases, coordinate the recruitment of Spt6 to transcribed genes in vivo.
Project description:According to previous studies, during Drosophila embryogenesis, RNA polymerase II is recruited to promoters at developmental stages preceding the stages of active transcription of genes. This work is aimed at exploring whether this mechanism is used during Drosophila metamorphosis. We performed ChIP-Seq analysis using antibodies to various modifications of RNA polymerase II (total, Pol II CTD Ser5P and Pol II CTD Ser2P), as well as to subunits of NELF, DSIF, PAF complexes and Brd4/Fs(1)h that control transcription elongation. We found that like in mid-embryogenesis during metamorphosis, promoters bind RNA polymerase II in the "paused" state preparing for activation at later stages of development. During mid-embryogenesis, RNA polymerase II in "pause" is phosphorylated at Ser5 and Ser2 of Rpb1 CTD and binds NELF, DSIF, and PAF complexes, but not Brd4/Fs(1)h. During metamorphosis, the "paused" RNA polymerase II complex includes Brd4/Fs(1)h in addition to NELF, DSIF, and PAF. The RNA polymerase II in this complex is phosphorylated at Ser5 at Rpb1 CTD, but not at Ser2.
Project description:During eukaryotic transcription, RNA polymerase II undergoes dynamic post-translational modification on the C-terminal domain (CTD) of the largest subunit , generating a sophisticated PTM landscape for the spatiotemporal recruitment to transcriptional regulators. To delineate the protein interactomes recruited to Pol II at different stages of transcription, we in vitro reconstructed phosphorylation patterns of the CTD at Ser5 and Ser2 positions, the hallmark phosphorylation at the initation and productive elongation stages of transcription, respectively. Distinctive protein interactomes indicates different proteins are recruited to RNA polymerase II at different stages of transcription by the phosphorylation of Ser2 and Ser5 of the CTD heptads. Calcium Homeostasis Endoplasmic Reticulum Protein (CHERP) specifically binds to the Ser2 of the heptad. The loss of the interaction between CHERP and Pol II results in broad alternative splicing events. Our method points to a new method to distinguish the PTM codes that coordinate the transcription process.
Project description:In Saccharomyces cerevisiae short non-coding RNA (ncRNA) generated by RNA Polymerase II (Pol II) are terminated by the NRD complex consisting of Nrd1, Nab3 and Sen1. We now show that Pcf11, a component of the cleavage and polyadenylation complex (CPAC), is generally required for NRD-dependent transcription termination through the action of its CTD interacting domain (CID). Pcf11 localizes downstream of Nrd1 on NRD terminators, and its recruitment depends on Nrd1. Furthermore mutation of the Pcf11 CID results in Nrd1 retention on chromatin, delayed degradation of ncRNA and restricts Pol II CTD Ser2 phosphorylation and Sen1-Pol II interaction. Finally, the pcf11-13 and sen1-1 mutant phenotypes are very similar as both accumulate RNA:DNA hybrids and display Pol II pausing downstream of NRD terminators. We predict a mechanism whereby Nrd1 and Pcf11 exchange on chromatin facilitates Pol II pausing and CTD Ser2-P phosphorylation. This in turn promotes Sen1 activity that is required for NRD-dependent transcription termination in vivo.
Project description:In Saccharomyces cerevisiae short non-coding RNA (ncRNA) generated by RNA Polymerase II (Pol II) are terminated by the NRD complex consisting of Nrd1, Nab3 and Sen1. We now show that Pcf11, a component of the cleavage and polyadenylation complex (CPAC), is generally required for NRD-dependent transcription termination through the action of its CTD interacting domain (CID). Pcf11 localizes downstream of Nrd1 on NRD terminators, and its recruitment depends on Nrd1. Furthermore mutation of the Pcf11 CID results in Nrd1 retention on chromatin, delayed degradation of ncRNA and restricts Pol II CTD Ser2 phosphorylation and Sen1-Pol II interaction. Finally, the pcf11-13 and sen1-1 mutant phenotypes are very similar as both accumulate RNA:DNA hybrids and display Pol II pausing downstream of NRD terminators. We predict a mechanism whereby Nrd1 and Pcf11 exchange on chromatin facilitates Pol II pausing and CTD Ser2-P phosphorylation. This in turn promotes Sen1 activity that is required for NRD-dependent transcription termination in vivo. ChIP-seq with antibody against pol II in wild type and Pcf11 mutants: Pcf11-2, Pcf11-9 and Pcf11-13 grown at 25C and 37C along with input samples
Project description:Spt6 is a multifunctional histone chaperone involved in the maintenance of chromatin structure during elongation by RNA polymerase II (Pol II). Spt6 has a tandem SH2 (tSH2) domain within its C-terminus that recognizes Pol II CTD peptides phosphorylated on Ser2, Ser5 or Try1 in vitro. Deleting the tSH2 domain, however, only has a partial effect on Spt6 occupancy in vivo, suggesting that more complex mechanisms are involved in the Spt6 recruitment. Our results show that the Ser2 kinases Bur1 and Ctk1, but not the Ser5 kinase Kin28, cooperate in recruiting Spt6, genome-wide. Interestingly, the Ser2 kinases promote the association of Spt6 in early transcribed regions and not toward the 3' end of genes, where phosphorylated Ser2 reaches its maximum level. Additionally, our results uncover an unexpected role for histone deacetylases (Rpd3 and Hos2) in promoting Spt6 interaction with elongating Pol II. Finally, our data suggest that phosphorylation of the Pol II CTD on Tyr1 promotes the association of Spt6 with the 3' end of transcribed genes, independently of Ser2 phosphorylation. Collectively, our results show that a complex network of interactions, involving the Spt6 tSH2 domain, CTD phosphorylation and histone deacetylases, coordinate the recruitment of Spt6 to transcribed genes in vivo. We examined the genome-wide distribution (using ChIP-chip) of Spt6. Spt6 occupancy was also assayed in mutants for CTD Serine 2 and Serine 5 kinases and in mutants for histone deacetylases. ChIPs were performed with a Myc-tagged version of Spt6. Most ChIPs (in Cy5) were hybridyzed against a control ChIP sample from an isogenic non-tagged strain (in Cy3). In the ChIP experiments with the spt6-202del mutant, non immunoprecipitated DNA (input) was used as the control. In addition to Spt6 ChIPs, the project includes RNAPII (Rpb3) ChIP-chip datasets, where an anti-Rpb3 antibody was used to ChIP RNAPII and non immunoprecipitated DNA (input) was used as the control. All ChIP-chip experiments were done in duplicates. Each microarray was normalized using the Lima Loess and replicates were combined using a weighted average method as previously described (Pokholok et al., 2005).
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:At the 3'-ends of genes, RNA polymerase (Pol) II is dephosphorylated at tyrosine 1 residues of its C-terminal domain (CTD), resulting in recruitment of transcription termination factors. We show that the multisubunit cleavage and polyadenylation factor (CPF) is a Pol II CTD phosphatase and its Glc7 subunit is required for Tyr1 dephosphorylation at the poly-adenylation site and Pol II termination in vivo. ChIP-chip was performed to examine the effect of Glc7 nuclear depletion on genome-wide Pol II occupancy [using ?-Rpb3 (1Y26, cat. no. W0012, neoclone) antibody] and CTD tyrosine 1 phosphorylation levels [using ?-TyrY1P (3D12, D. Eick) antibody].
Project description:Determination of RNAPII, Rrd1-Myc, RNAPII-Ser2-P, RNAPII-Ser5-P abundance between wildtype and rrd1 deletion strains under rapamycin or control treatments.Rapamycin is an anticancer agent and immunosuppressant that acts by inhibiting the TOR signaling pathway. In yeast, rapamycin mediates a profound transcriptional response for which the RRD1 gene is required. To further investigate this connection, we performed genome-wide association studies of RNA polymerase II (RNAPII) and Rrd1 in response to rapamycin and demonstrate that Rrd1 colocalizes with RNAPII on actively transcribed genes and both are recruited to rapamycin responsive genes. Strikingly, when Rrd1 is lacking, RNAPII remains inappropriately associated to ribosomal genes and fails to be recruited to rapamycin responsive genes. This occurs independently of TATA box binding protein recruitment. Furthermore, Rrd1 modulates the phosphorylation status of RNAPII CTD and additional evidence suggests that Rrd1 is involved in various transcriptional stress responses. We propose that Rrd1 is a novel transcription elongation factor that fine-tunes the transcriptional stress response of RNAPII.