NMR characterization of the interaction between the PUB domain of peptide:N-glycanase and ubiquitin-like domain of HR23

► PUB domain of PNGase binds to HR23–UBL more preferentially than ubiquitin chains. ► 3D model of the PUB–UBL complex is presented based on NMR data. ► The PUB–UBL complex is mediated by electrostatic interactions. ► PUB binds the UBL surface involved in intramolecular interaction with HR23–UBA. ► PNGase-PUB could serve as a putative activator of HR23 in ERAD. PUB domains are identified in several proteins functioning in the ubiquitin (Ub)–proteasome system and considered as p97-binding modules. To address the further functional roles of these domains, we herein characterized the interactions of the PUB domain of peptide:N-glycanase (PNGase) with Ub and Ub-like domain (UBL) of the proteasome shuttle factor HR23. NMR data indicated that PNGase-PUB exerts an acceptor preferentially for HR23–UBL, electrostatically interacting with the UBL surface employed for binding to other Ub/UBL motifs. Our findings imply that PNGase-PUB serves not only as p97-binding module but also as a possible activator of HR23 in endoplasmic reticulum-associated degradation mechanisms. PNGasebinds to HR23A by affinity chromatography technology (View interaction) PNGase and HR23Abind by nuclear magnetic resonance (View interaction) PNGase and HR23Bbind by nuclear magnetic resonance (View interaction)