Adaptor-Specific Peptide Inhibitors of the Ubiquitin-Chain-Dependent Unfolding Activity of the Human p97(VCP)–UFD1–NPL4 Complex

The AAA-ATPase p97, a key component of the ubiquitin-proteasome system (UPS), collaborates with its cofactor, the UFD1-NPL4 (UN) heterodimer, to unfold ubiquitinated substrates leading to proteasomal degradation. In this study, we report the development of novel peptide inhibitors that specifically target the p97-UN complex. These inhibitors are designed based on the NPL4-binding motif (NBM) of UFD1 and disrupt the interaction between p97 and the UN heterodimer. Our results demonstrate that these peptides effectively inhibit the unfolding activity of p97-UN, suggesting their potential as a therapeutic strategy for diseases associated with UPS dysfunction, such as cancer and neurodegenerative disorders. This work provides the first mechanistic insights into the inhibition of p97-UN by high-affinity peptide inhibitors and introduces promising candidates for drug development targeting the stable p97-UN complex in cells.