Cdc48’s interactions play a role in the cellular oxidative response in an aging-dependent manner

The cellular redox status has long been linked to many different cellular functions and behaviors, including protein quality control (PQC) and aging. The prominent molecular machine Cdc48 (p97/VCP in mammals) is one of the key players involved in PQC, shuttling misfolded proteins from various organelles to degradation. Through a wide range of N-terminal interactions with both substrates and varying cofactors, Cdc48 recognizes ubiquitin-tagged proteins targeted for proteasomal degradation. Here, we show that yeast Cdc48 is a redox-switch protein, with aging-associated oxidation of a thiol-switch in the conserved Cys115. Using redox mass spectrometry, we characterize the oxidation status of Cdc48’s cysteine residues in the shift from the early- to late-stationary stages, the latter correlating with post-diauxic conditions. Following increased oxidation during chronological aging, Cdc48’s interactome undergoes a proteomic-scale rearrangement and leads to an increased association with antioxidants. We found that the oxidation status of Cys115 mediates the activity of Cdc48 and its interaction with canonic cofactors and subsequent involvement in maintaining protein homeostasis through degradation, the unfolded protein response (UPR), cellular viability, and protein localization during chronological aging. This work not only points to a new thiol switch protein in the protein degradation pathway, but also defines new roles for Cdc48 in chronological aging.