Structural studies of a HECT ubiquitin ligase, Rsp5
Abstract
The ubiquitination system within cells is a multi-step process that involves numerous enzymes working together to direct proteins to proteolytic and non-proteolytic pathways. Ubiquitin-activating enzyme (E1), ubiquitin conjugating enzymes (E2), and ubiquitin ligases (E3) work in tandem to transfer ubiquitin to target substrates. Specifically, HECT E3s are able to confer substrate specificity as well as directly ubiquitinate target substrate, making these ligases particularly interesting. Our research focuses on Rsp5, an essential Saccharomyces cerevisiae HECT E3, and its interactions with substrate throughout the ubiquitination process. The goal of our research is to elucidate the mechanism by which a HECT E3 binds to and ubiquitinates its substrates. To this end, we have crystallized two Rsp5 complexes; Rsp5:UbcH5a as well as a non covalently bound Rsp5:Ub complex. Analysis of these structures agree with the current model of Ub transfer from E2 to E3 and also suggest a possible mechanism for substrate ubiquitination as well as poly-ubiquitination chain formation.
Degree
Ph.D.
Advisors
Chen, Purdue University.
Subject Area
Biochemistry|Biophysics
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.