Conformational Flexibility Underlies Ubiquitin Ligation Mediated by the WWP1 HECT Domain E3 Ligase

Abstract

Ubiquitin ligases (E3) select proteins for ubiquitylation, a modification that directs altered subcellular trafficking and/or degradation of the target protein. HECT domain E3 ligases not only recognize, but also directly catalyze, ligation of ubiquitin to their protein substrates. The crystal structure of the HECT domain of the human ubiquitin ligase WWP1/AIP5 maintains a two-lobed structure like the HECT domain of the human ubiquitin ligase E6AP. While the individual N and C lobes of WWP1 possess very similar folds to those of E6AP, the organization of the two lobes relative to one another is different from E6AP due to a rotation about a polypeptide hinge linking the N and C lobes. Mutational analyses suggest that a range of conformations achieved by rotation about this hinge region is essential for catalytic activity.

Activation of the E3 ubiquitin ligase Itch through a phosphorylation-induced conformational change

“…HECT domains, unlike RING finger domains, are structurally similar to E2s, including an active Cys residue that transfers the activated Ub from the E2, first onto itself, and then onto its target protein (2,3). Recent structural studies have revealed a hinge region that provides conformational flexibility to the N-and C-terminal halves of the HECT domain and may also be involved in regulation of its activity (15).…”

Clinical and genetic aspects of Angelman syndrome

“…69,70 This reaction occurs in a catalytic region of E6AP termed the homologous to E6AP C terminus (HECT) domain. 71 After ubiquitin attachment, E6AP can add ubiquitins onto the first ubiquitin to create a polyubiquitylated substrate that can then be targeted for degradation through the 26S proteasome complex. The E6AP is one of many E3 ligases that function in the E3 component of the ubiquitin cycle; E1 and E2 proteins respectively activate and transfer the ubiquitin to E3.…”

The WW domain containing E3 ubiquitin protein ligase 1 upregulates ErbB2 and EGFR through RING finger protein 11

“…Nedd4-like E3s can be identified by their distinctive domain structure: an HECT domain at the C terminus for the ubiquitin transfer (Verdecia et al, 2003), a C2 domain at the N terminus for calcium-dependent phospholipid binding, and 2-4 WW domains in the middle for protein-protein interaction with PY motifs (Mosser et al, 1998). It has been well established that the WW domains of WWP1 can directly bind to the PY motifs of their substrates, such as Smad2 (Seo et al, 2004), Smad7 (Komuro et al, 2004), Runx2 (Jones et al, 2006;Shen et al, 2006) and KLF5 (Chen et al, 2005).…”