SUMOylation of Psmd1 Controls Adrm1 Interaction with the Proteasome

•The 19S regulatory particle (19S-RP) subunit Psmd1 is a SUMO2/3 conjugation target•PIASy and xSENP1 mediate Psmd1 SUMOylation and deSUMOylation, respectively•Psmd1 SUMOylation controls its binding to Adrm1, a ubiquitin receptor of the 19S-RP

SummarySUMOylation is the covalent conjugation of SUMO polypeptides to cellular target proteins. Psmd1 is a subunit of the proteasomal 19S regulatory particle that acts as a docking site for Adrm1, another proteasome subunit that recruits ubiquitinated substrates for proteolysis. Here, we show that the SUMO deconjugating enzyme xSENP1 specifically interacts with Psmd1 and that disruption of xSENP1 targeting delays mitotic exit. Psmd1 becomes SUMOylated through the action of the SUMO E3 enzyme PIASy. We mapped SUMOylation sites within Psmd1 and found that SUMOylation of a critical lysine immediately adjacent to the Adrm1-binding domain regulates the association of Adrm1 with Psmd1. Together, our findings suggest that the interaction of Psmd1 with Adrm1 is controlled by SUMOylation in a manner that may alter proteasome composition and function. These findings demonstrate a mechanism for regulation of ubiquitin-mediated protein degradation by ubiquitin-like proteins of the SUMO family.

Graphical AbstractFigure optionsDownload full-size imageDownload as PowerPoint slide