Mayekar, Manasi
(2013)
UNCOVERING THE MECHANISM OF CHROMATIN ASSOCIATION OF THE PAF1 TRANSCRIPTION ELONGATION COMPLEX.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
This is the latest version of this item.
Abstract
Paf1C co-localizes with Pol II and influences gene expression by regulating transcription initiation, elongation and termination. Some crucial functions of Paf1C include promoting co-transcriptional histone modifications and recruiting termination factors. The mechanism of chromatin recruitment of Paf1C was obscure. We identified the importance of a conserved region within the Rtf1 subunit of Paf1C, termed the ORF association region (OAR), in chromatin-tethering of Paf1C. I found that the interaction of Paf1C with the transcription elongation factor Spt5 was mediated by the Rtf1 OAR and the Spt5 C-terminal region (CTR). Binding assays established the direct nature of the Rtf1-Spt5 interaction and the sufficiency of the Rtf1 OAR and the Spt5 CTR for this interaction. ChIP assays demonstrated the ability of the OAR to mimic the chromatin association pattern of Paf1C, independent of Paf1C but dependent on the Spt5 CTR and the Bur1 kinase. This suggests that the targeting of the OAR tethers Paf1C to chromatin. Collectively, these results provide a molecular mechanism for coupling Paf1C with the transcription machinery.
Additionally, I found that substitution of OAR residues predicted to be important for the human Rtf1 OAR-Spt5 CTR interaction in the OAR-CTR co-crystal impaired the chromatin association of Paf1C supporting the relevance of the co-crystal interactions. Furthermore, I showed that strains that are doubly mutated in the OAR and the Cdc73 C-domain exhibited cumulative reduction in Paf1C chromatin occupancy. Consistently, I showed that cells lacking both the OAR and the C-domain lose Paf1C-mediated histone modifications. This indicates that the Rtf1 OAR and the Cdc73 C-domain facilitate dual-attachment of Paf1C to chromatin.
My work has also provided better understanding of the function of the histone modification domain (HMD) of Rtf1. I found that overexpression of the HMD was essential for it to promote histone modifications. Additionally, I showed that the HMD is sufficient for the H2B K123 Ub, the mark upstream of the H3 K4 and H3 K79 methylation events, but the rest of Paf1C is required for the HMD to stimulate H3 K4 Me3 modification. Cumulatively, my findings provide additional insight into the regulation of histone modifications by the Rtf1 HMD.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
18 November 2013 |
| Date Type: |
Publication |
| Defense Date: |
30 October 2013 |
| Approval Date: |
18 November 2013 |
| Submission Date: |
15 November 2013 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
208 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Biochemistry and Molecular Genetics |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Chromatin, Transcription, Paf1 complex, Histone modifications, Rtf1, Spt5 |
| Date Deposited: |
18 Nov 2013 15:29 |
| Last Modified: |
15 Nov 2016 14:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/20010 |
Available Versions of this Item
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UNCOVERING THE MECHANISM OF CHROMATIN ASSOCIATION OF THE PAF1 TRANSCRIPTION ELONGATION COMPLEX. (deposited 18 Nov 2013 15:29)
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