Addressing The Role Of The Not4 E3 Ubiquitin Ligase During DNA Damage-Induced Degradation Of RNAPII In Budding Yeast

Open Access
Author:
Beebe, Laura M
Area of Honors:
Biochemistry and Molecular Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Joseph Reese, Thesis Supervisor
  • Joseph Reese, Honors Advisor
  • David Gilmour, Faculty Reader
Keywords:
  • DNA Damage Repair
  • RNA Polymerase
  • Yeast
  • Ubiquitin
  • Ccr4-Not
  • Gene Regulation
Abstract:
Ccr4-Not is a multi-subunit gene regulatory protein complex that has been highly conserved in eukaryotes. Although first thought to solely act as a negative regulator for transcription, it has since been shown that Ccr4-Not is the major cytoplasmic deadenylase in yeast, and has subsequent functions in mRNA decay and control, RNA export, and translational repression. Most relevant to this study, the complex has been shown to have ubiquitylation activity—a process which can target proteins for degradation or modulate their activity. It has also been shown that ubiquitin proteases, such as Ubp3, are involved in transcription and are important to promoting cellular resistance to DNA damage. Connecting these two notions, previous work from the Reese laboratory has found that Not4, a subunit of Ccr4-Not, possesses a RING domain causing ubiquitin ligase activity involved in Rpb1 (the large subunit of RNA Polymerase II) turnover and degradation after DNA damage. In this work, we both verify this result and inform further study on whether Ccr4-Not plays a direct or indirect role in Rpb1 ubiquitylation and degradation, based on its genetic interactions with other enzymes in the transcription-coupled repair (TCR) and ubiquitin/proteasome pathways.