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bioRxiv · 10.64898/2026.02.26.708172

Faf2/Ubx2 potentiates p97/Cdc48 segregase activity via functional priming and reinforcement of the UT3 domain in Ufd1

Ren, Y.·Zheng, Q.·Duan, Y.·Xu, Z.·Qu, Q.·Weng, Y.·Cui, S.·Yu, Y.·Pan, M.·Liu, L.
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Abstract

The AAA+ segregase p97/Cdc48 extracts poly-ubiquitinated proteins from entrenched cellular environments to maintain proteostasis. However, its functional capacity is not uniform; extracting substrates from dense assemblies like stress granules or membrane necessitates a fully potentiated state. Here, using precisely synthesized ubiquitinated substrates, we show that the Faf2/Ubx2 cofactor hyperactivates p97/Cdc48, lowering its minimal ubiquitin chain requirement and broadening linkage specificity. Cryo-EM analysis of the activated complex demonstrates that Faf2/Ubx2 potentiates p97/Cdc48 segregase activity by structurally remodeling the substrate recognition module (K48-diUbProx) and priming its engagement with the AAA+ motor (p97/Cdc48-Npl4). These coordinated actions establish a pump-unit architecture that drives efficient substrate processing. Our findings illuminate a conserved mechanism that unlocks the maximal capacity of p97/Cdc48 and provide a blueprint for therapeutically targeting its hyper-activated state in disease.

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Ren, Y., Zheng, Q., Duan, Y., Xu, Z., Qu, Q., Weng, Y., Cui, S., Yu, Y., Pan, M., Liu, L.. 2026-02-27. Faf2/Ubx2 potentiates p97/Cdc48 segregase activity via functional priming and reinforcement of the UT3 domain in Ufd1. https://doi.org/10.64898/2026.02.26.708172

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