The Role of the CTD Phosphatase Rtr1 and Post-translational Modifications in Regulation of RNA Polymerase II PDF Download
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Author: Mary L. Cox
Publisher:
ISBN:
Category : Cellular signal transduction
Languages : en
Pages : 186
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Book Description
RNA polymerase II (RNAPII) is regulated by multiple modifications to the C-terminal domain (CTD) of the largest subunit, Rpb1. This study has focused on the relationship between hyperphosphorylation of the CTD and RNAPII turnover and proteolytic degradation as well as post-translational modifications of the globular core of RNAPII. Following tandem affinity purification, western blot analysis showed that MG132 treated RTR1 ERG6 deletion yeast cells have accumulation of total RNAPII and in particular, the hyperphosphorylated form of the protein complex. In addition, proteomic studies using MuDPIT have revealed increased interaction between proteins of the ubiquitin-proteasome degradation system in the mutant MG132 treated yeast cells as well as potential ubiquitin and phosphorylation sites in RNAPII subunits, Rpb6 and Rpb1, respectively. A novel Rpb1 phosphorylation site, T1471-P, is located in the linker region between the CTD and globular domain of Rpb1 and will be the focus of future studies to determine biological significance of this post-translational modification.
Author: Mary L. Cox
Publisher:
ISBN:
Category : Cellular signal transduction
Languages : en
Pages : 186
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Book Description
RNA polymerase II (RNAPII) is regulated by multiple modifications to the C-terminal domain (CTD) of the largest subunit, Rpb1. This study has focused on the relationship between hyperphosphorylation of the CTD and RNAPII turnover and proteolytic degradation as well as post-translational modifications of the globular core of RNAPII. Following tandem affinity purification, western blot analysis showed that MG132 treated RTR1 ERG6 deletion yeast cells have accumulation of total RNAPII and in particular, the hyperphosphorylated form of the protein complex. In addition, proteomic studies using MuDPIT have revealed increased interaction between proteins of the ubiquitin-proteasome degradation system in the mutant MG132 treated yeast cells as well as potential ubiquitin and phosphorylation sites in RNAPII subunits, Rpb6 and Rpb1, respectively. A novel Rpb1 phosphorylation site, T1471-P, is located in the linker region between the CTD and globular domain of Rpb1 and will be the focus of future studies to determine biological significance of this post-translational modification.
Author: Michael J. Berna (Sr.)
Publisher:
ISBN:
Category : Genetic transcription
Languages : en
Pages : 166
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Book Description
The C-terminal domain (CTD) of the RNA polymerase II (RNAPII) subunit Rpb1 must exist in a hypophosphorylated state prior to forming a competent transcription initiation complex. However, during transcription, specific kinases and phosphatases act on the RNAPII CTD to regulate its phosphorylation state, which serves to recruit sequence-specific and general transcription factors at the appropriate stage of transcription. A key phosphatase involved in this process, Rtr1 (Regulator of Transcription 1), was shown to regulate a key step important for transcription elongation and termination. Although the role that Rtr1 plays in regulating RNAPII transcription has been described, the mechanism involved in the recruitment of Rtr1 to RNAPII during transcription has not been elucidated in yeast. Consequently, the present work utilized both affinity purification schemes in Saccharomyces cerevisiae and mass spectrometry to identify key Rtr1-interacting proteins and post-translational modifications that potentially play a role in recruiting Rtr1 to RNAPII. In addition to RNAPII subunits, which were the most consistently enriched Rtr1-interacting proteins, seven proteins were identified that are potentially involved in Rtr1 recruitment. These included PAF complex subunits (Cdc73, Ctr9, Leo1), the heat shock protein Hsc82, the GTPase Npa3, the ATPase Rpt6, and Spn1. Indirect evidence was also uncovered that implicates that the CTDK-I complex, a kinase involved in RNAPII CTD phosphorylation, is important in facilitating interactions between Rtr1, RNAPII, and select transcription factors. Additionally, a putative phosphorylation site was identified on Ser217 of Rtr1 that may also play a role in its recruitment to RNAPII during transcription.
Author: Joshua Edward Mayfield
Publisher:
ISBN:
Category :
Languages : en
Pages : 336
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Book Description
RNA polymerase II is a highly regulated protein complex that transcribes all protein coding mRNA and many non-coding RNAs. A key mechanism that facilitates its activity is post-translational modification of the carboxyl-terminal domain of RNA polymerase II (CTD). This unstructured domain is conserved throughout eukaryotes and composed of repeats of the consensus amino acid heptad Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. This domain acts as a platform for the recruitment of transcriptional regulators that specifically recognize post-translational modification states of the CTD. The majority of our understanding of CTD modification comes from the use of phospho-specific antibodies, which provide identity and abundance information but give only low-resolution information for how these marks co-exist and interact at the molecular level. During my graduate work I sought to utilize the tools of chemical biology to investigate CTD modification in high resolution. Using a combination of chemical tools, analytical chemistry, and molecular biology I studied CTD modification in extremely high resolution. This work reveals the existence of interactions between CTD modifications, the influence of CTD sequence divergence on modification events, and presents initial data to support a role for previously encoded modifications to direct subsequent modification events
Author: Susanne Jutta Hoheisel
Publisher:
ISBN:
Category :
Languages : en
Pages : 328
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 261
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The C-terminal domain (CTD) of RNA polymerase II (Pol II) consists of conserved heptapeptide repeats that are subject to sequential waves of posttranslational modifications during specific stages of the transcription cycle. These patterned modifications have led to the postulation of the CTD code hypothesis, where stage-specific patterns define a spatiotemporal code that is recognized by the appropriate interacting partners. This thesis summarizes our efforts to define the CTD code, identify the writers and erasers, and explore the function of the code during transcription. We examined the genome-wide distributions of the phospho-serine modifications. We found unique profile clusters for the "early" serine 5 phosphorylation (Ser5-P), the "mid" serine 7 phosphorylation (Ser7-P), and the "late" serine 2 phosphorylation (Ser2-P). We also identified gene class-specific patterns and find widespread co-occurrence of the CTD marks. These phosphorylation marks are placed by an array of phospho-serine kinases. We identified Kin28 (CDK7) as a Ser7-P kinase, and specific inhibition of Kin28 caused a significant decrease in Ser7-P levels at promoters. However, the promoter-distal Ser7-P marks are not remnants of early phosphorylation by Kin28. Instead, we find that Bur1 (CDK9) is positioned to phosphorylate Ser7 within the coding regions. Next, we investigated the phosphatases that erase the CTD code. The importance of these enzymes is emphasized by our observation that an inability to remove Ser7-P marks is lethal. We identified Ssu72 as a Ser7-P phosphatase, and inactivation of Ssu72 triggers a drastic remodeling of Ser7-P distributions across protein-coding and non-coding genes. Furthermore, we report that removal of all phospho-CTD marks during transcription termination is mechanistically coupled. An inability to remove these marks prevents Pol II from terminating efficiently at both gene classes and also impedes proper transcription initiation. Interestingly, Ssu72 seems to be enriched within introns, peaking at the 3' splice site. Interestingly, we do not find polymerase pausing at the 3' splice site or at the terminal exons, as has been previously reported. Instead, we believe Ssu72 may be involved in facilitating the cotranscriptional recruitment of splicing factors by establishing a chromatin state accommodating to splicing.
Author: Jonathan Donald Chesnut
Publisher:
ISBN:
Category :
Languages : en
Pages : 280
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Author:
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ISBN:
Category : Artists, Australian
Languages : en
Pages :
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Author: Helen Cho
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ISBN:
Category :
Languages : en
Pages : 346
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Author: Paolo Licciardo
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Category :
Languages : en
Pages : 215
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Author: Bede Portz
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Category :
Languages : en
Pages :
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RNA polymerase II contains a repetitive and intrinsically disordered C-Terminal Domain (CTD) composed of heptad repeats of the consensus sequence YSPTSPS. The CTD can be heavily phosphorylated and serves as a scaffold, interacting with factors involved in transcription initiation, elongation, termination, RNA processing and chromatin modification. Despite its role as a nexus of eukaryotic gene regulation, the structure of the CTD and the structural implications of CTD phosphorylation, are poorly understood. Additionally, there is an increasing awareness of the importance of intrinsically disordered proteins (IDPs) that function without adopting a stably folded structure. Here I present a biophysical and biochemical interrogation of the structure of the full-length CTD of D. melanogaster, which I conclude is a compact random coil. I find that the repetitive CTD is structurally heterogeneous as evidenced by a discontinuous pattern of cutting in limited proteolysis assays. Small Angle X-Ray scattering (SAXS) is a method ideally suited for the structural interrogation of large IDPs and can be employed to measure the size of a protein and to monitor structural changes in response to post-translational modification. Using SAXS I determined that phosphorylation by the kinase P-TEFb caused an increase in CTD radius and stiffness. Limited proteolysis of the phosphorylated CTD showed these gross structural changes are accompanied by increased protease accessibility and an alteration in relative protease accessibility across the length of the CTD.Additionally, we show that the human CTD is also structurally heterogeneous and able to substitute for the Drosophila melanogaster CTD in supporting the development of flies to adulthood. These finding implicate conserved structural organization, not a precise array of heptad motifs, as important to CTD function.The CTD is attached to the catalytic core of Pol II via a linker. I show that this linker is more compact than the CTD repeats and serves as an independent structural unit. The phosphorylated linker-CTD remains flexible relative to the phosphorylated CTD alone. Together, these results support a mechanism by which phosphorylation reduces the conformational entropy of the CTD, generating a more binding competent dock for CTD:protein interactions, with the linker region maintaining the ability of CTD bound factors to sample the 3-dimensional space which may be required for RNA processing and histone modification.The data described herein represent the most thorough structural characterization to date of the full length CTD on the global and local scales, examining both the overall size and local structural organization of the CTD. These studies establish the Drosophila CTD as an attractive model for the biophysical, biochemical and genetic interrogation of the structure and function of the CTD from a developmentally complex organism.
