Structural and Functional Characterization of Ube2H, a Ubiquitin-Conjugating Enzyme with a C-terminal Extension

Abstract

The human proteome contains over forty ubiquitin-conjugating enzymes, each harboring a conserved core domain. Despite their structural similarities, E2s must discriminate between hundreds of E3 ligases to interact specifically with their cognate partners. Structural and functional characterization of E2s in the last few decades has revealed unique mechanistic details for each E2 studied thus far, but no universal rule appears to govern how E2 enzymes specifically recognize their cognate binding partners. Many E2s remain uncharacterized and promise to reveal novel strategies by which these apparently simple enzymes achieve specificity in both E3 binding and Ub transfer. Ube2H is a human E2 enzyme with an uncharacterized C-terminal extension of 32 residues. The extension is phylogenetically conserved, but its function is unknown. In this thesis, I employ biophysical and biochemical techniques to investigate the structural and biochemical function of Ube2H’s C-terminal extension, both alone and in the presence of putative E3 ligases and binding partners.