A Structural Element within the HUWE1 HECT Domain Modulates Self-ubiquitination and Substrate Ubiquitination Activities |
| |
Authors: | Renuka K. Pandya James R. Partridge Kerry Routenberg Love Thomas U. Schwartz Hidde L. Ploegh |
| |
Affiliation: | From the ‡Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142 and ;the §Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 |
| |
Abstract: | E3 ubiquitin ligases catalyze the final step of ubiquitin conjugation and regulate numerous cellular processes. The HECT class of E3 ubiquitin (Ub) ligases directly transfers Ub from bound E2 enzyme to a myriad of substrates. The catalytic domain of HECT Ub ligases has a bilobal architecture that separates the E2 binding region and catalytic site. An important question regarding HECT domain function is the control of ligase activity and specificity. Here we present a functional analysis of the HECT domain of the E3 ligase HUWE1 based on crystal structures and show that a single N-terminal helix significantly stabilizes the HECT domain. We observe that this element modulates HECT domain activity, as measured by self-ubiquitination induced in the absence of this helix, as distinct from its effects on Ub conjugation of substrate Mcl-1. Such subtle changes to the protein may be at the heart of the vast spectrum of substrate specificities displayed by HECT domain E3 ligases. |
| |
Keywords: | Enzymes Enzymes/Structure Protein/Structure E3 Ubiquitin Ligase Ubiquitination |
|