Bohm S, et al. (2011) Cellular functions of ufd2 and ufd3 in proteasomal protein degradation depend on cdc48 binding. Mol Cell Biol 31(7):1528-39
Abstract: The chaperone-related AAA ATPase Cdc48 (p97/VCP in higher eukaryotes) segregates ubiquitylated proteins for subsequent degradation by the 26S proteasome or for non-proteolytic fates. The specific outcome of Cdc48 activity is controlled by the evolutionary conserved cofactors Ufd2 and Ufd3, which antagonistically regulate the substrates ubiquitylation state. In contrast to Ufd3, the interaction between the ubiquitin chain elongating enzyme Ufd2 and Cdc48 has not been precisely mapped. Consequently, it is still unknown if physiological functions of Ufd2 in fact require Cdc48 binding. Here, we show that Ufd2 binds to the C-terminal tail of Cdc48, unlike the human Ufd2 homologue E4B which interacts with the N domain of p97. The binding sites for Ufd2 and Ufd3 on Cdc48 overlap and depend critically on the conserved residue Y834, but are not identical. Yeast cdc48 mutants altered in residue Y834 or lacking the C-terminal tail are viable and exhibit normal growth. Importantly, however, loss of Ufd2 and Ufd3 binding in these mutants phenocopies defects of Deltaufd2 and Deltaufd3 mutants in the ubiquitin fusion degradation (UFD) and Ole1 fatty acid desaturase activation (OLE) pathways. These results indicate that key cellular functions of Ufd2 and Ufd3 in proteasomal protein degradation require their interaction with Cdc48.
|Status: Published||Type: Journal Article||PubMed ID: 21282470|
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