Characterization of the Function and Regulation of Cullin Ring E3 Ubiquitin Ligases

Abstract

Cullin RING E3 ubiquitin ligases constitute the largest family of cellular ubiquitin ligases. They mediate the ubiquitination and degradation of numerous cellular substrate proteins and are hence involved in diverse cellular functions. In the Cullin E3 ligase structure, the cullin proteins serve as scaffolds for the assembly of the RING protein and substrate receptor subunits. Cullin E3 ligases are activated via the conjugation with the ubiquitin-like protein Nedd8 onto the cullin scaffold protein. Cullin neddylation leads to a conformational change in the cullin C-terminus/Rbx1 structure that is essential for facilitating the ubiquitin transfer onto the substrate. Thus, cullin neddylation is essential in CRL function and regulation. In my study, I characterized two inhibitors of cullin neddylation, dominant-negative Ubc12 and the Nedd8 E1 inhibitor MLN4924. In my further work, I have used these inhibitors to understand the regulation of Cullin E3 ligases and to identify novel Cullin E3 ligase substrates.