Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




Oliver Kerscher

Committee Members

Lizabeth Allison

Elizabeth J. Harbron

Helen A. Murphy


SUMO-targeted ubiquitin ligases (STUbLs) are a newly defined class of enzymes that attach ubiquitin to sumoylated substrates. STUbLs are conserved from yeast to humans and have been implicated in DNA repair, transcriptional regulation, and genome stability. Importantly, studies on STUbLs provide insight into the crosstalk between the SUMO and ubiquitin conjugation pathways. The budding yeast STUbL Slx5-Slx8 has few confirmed ubiquitylation substrates, but many more are believed to exist. For example, Slx5-Slx8 ubiquitylates the DNA damage repair protein Rad52 in vitro; in vivo, the transcriptional regulator Mot1 and the transcription factor MAT?2 appear to be promising substrates. Recently, we observed a novel colocalization between Slx5 and a septin protein, Cdc3, as well as a two-hybrid interaction between Slx5 and the SUMO E3 ligase Siz1. The goals of this study, therefore, were to determine whether Slx5-Slx8 can ubiquitylate these substrates in vitro and to investigate the role that sumoylation plays in STUbL targeting. Here, we report that Slx5 interacts with the SUMO E3 ligase Siz1 in in vitro ubiquitylation and pulldown assays and that SUMO2 chains are required for the ubiquitylation of a substrate by the human STUbL RNF4.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.


Thesis is part of Honors ETD pilot project, 2008-2013. Migrated from Dspace in 2016.

On-Campus Access Only