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The roles of the Saccharomyces cerevisiae Paf1 complex in regulating transcriptional repression

Crisucci, Elia Marie (2011) The roles of the Saccharomyces cerevisiae Paf1 complex in regulating transcriptional repression. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The conserved Paf1 complex is important for proper gene expression in both yeast and humans. The Paf1 complex has been shown to repress the transcription of numerous genes. However, the mechanism by which the Paf1 complex mediates transcriptional repression remains largely unstudied. Here I use ARG1 as a model gene to investigate transcriptional repression by the Paf1 complex in Saccharomyces cerevisiae. Interestingly, I found that Paf1 complex-dependent histone modifications that are normally associated with active transcription are enriched on the ARG1 coding region and contribute to repression. The Rtf1 subunit of the Paf1 complex appears to mediate ARG1 repression primarily through histone H2B ubiquitylation and histone H3 K4 methylation. However, Paf1 has repressive functions aside from these histone modifications. Interestingly, occupancy of the activator Gcn4 is increased at the ARG1 promoter in paf1Δ cells, resulting in ARG1 derepression that is dependent on the histone acetyltransferase Gcn5 and histone H3 acetylation sites. Together my results suggest that Paf1 mediates ARG1 repression by preventing Gcn4 recruitment to the ARG1 promoter and subsequent histone H3 acetylation. I found that Paf1 does not alter nucleosome occupancy at the ARG1 promoter. However, I detect antisense transcription in the ARG1 promoter that positively correlates with ARG1 sense transcription. Interestingly, Paf1 prevents antisense transcription from traversing the ARG1 promoter, representing a potential mechanism by which the Paf1 complex controls promoter accessibility and ultimately ARG1 expression. Given these results, I hypothesize that the Paf1 complex mediates ARG1 repression partially by facilitating histone modifications that are refractory to ARG1 transcription and partially by inhibiting antisense transcription which controls promoter accessibility. Importantly, events that I observed at my model gene, ARG1, are demonstrated at other Paf1 complex-repressed genes.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Crisucci, Elia Marieemc22@pitt.eduEMC22
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairArndt, Karenarndt@pitt.eduARNDT
Committee MemberMartens, Josephmartens@pitt.eduMARTENS
Committee MemberBrodsky, Jeffreyjbrodsky@pitt.eduJBRODSKY
Committee MemberSchmidt, Martinmcs2@pitt.eduMCS2
Committee MemberGrabowski, Paulapag4@pitt.eduPAG4
Date: 16 September 2011
Date Type: Completion
Defense Date: 26 May 2011
Approval Date: 16 September 2011
Submission Date: 9 August 2011
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: chromatin; gene repression; histone modifications; Paf1 complex; transcription
Other ID:, etd-08092011-234909
Date Deposited: 10 Nov 2011 19:58
Last Modified: 15 Nov 2016 13:48


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