Enzymatic Analysis of WWP2 E3 Ubiquitin Ligase Using Protein Microarrays Identifies Autophagy-Related Substrates

ABSTRACT: WWP2 is a HECT E3 ligase that targets protein Lys residues for ubiquitination. As a member of the NEDD4 family of E3 ligases, WWP2 is comprised of an N-terminal C2 domain, four central WW domains, and a C-terminal catalytic HECT domain. The peptide segment between the middle WW domains, the 2,3-linker, can autoinhibit the catalytic domain and this can be relieved by phosphorylation at Tyr369. Several protein substrates of WWP2 have been identified, including the tumor suppressor lipid phosphatase PTEN, but the full substrate landscape and biological functions of WWP2 remain to be elucidated. Here we use protein microarray technology and the activated enzyme phosphomimetic mutant WWP2Y369E to identify potential WWP2 substrates. We identified 31 substrate hits for WWP2Y369E using protein microarrays of which three are the autophagy receptors, NDP52, OPTN, and SQSTM1. These three hits were validated with in vitro and cell-based transfection assays and the Lys ubiquitination sites on these proteins were mapped by mass spectrometry. Among the mapped ubiquitin sites on these autophagy receptors, many were previously identified in studies on the endogenous proteins. WWP2 knockout SH-SH5Y neuroblastoma cells using CRISPR-Cas9 showed a defect in mitophagy in a fashion that could be rescued by WWP2Y369E transfection. These studies suggest that WWP2-mediated ubiquitination of the autophagy receptors NDP52, OPTN, and SQSTM1 may positively contribute to the regulation of autophagy.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Escherichia Coli

SUBMITTER: Hanjie Jiang  

LAB HEAD: Philip A. Cole

PROVIDER: PXD031703 | Pride | 2022-05-20

REPOSITORIES: pride