title: Dfm1 forms distinct complexes with Cdc48 and the ER ubiquitin ligases and is required for ERAD.
abstract: Proteins imported into the endoplasmic reticulum (ER) are scanned for their folding status. Those that do not reach their native conformation are degraded via the ubiquitin-proteasome system. This process is called ER-associated degradation (ERAD). Der1 is known to be one of the components required for efficient degradation of soluble ERAD substrates like CPY(*) (mutated carboxypeptidase yscY). A homologue of Der1 exists, named Dfm1. No function of Dfm1 has been discovered, although a C-terminally hemagglutinin (HA)(3)-tagged Dfm1 protein has been shown to interact with the ERAD machinery. In our studies, we found Dfm1-HA(3) to be an ERAD substrate and therefore not suitable for functional studies of Dfm1 in ERAD. We found cellular, non-tagged Dfm1 to be a stable protein. We identified Dfm1 to be part of complexes which contain the ERAD-L ligase Hrd1/Der3 and Der1 as well as the ERAD-C ligase Doa10. In addition, ERAD of Ste6(*)-HA(3) was strongly dependent on Dfm1. Interestingly, Dfm1 forms a complex with the AAA-ATPase Cdc48 in a strain lacking the Cdc48 membrane-recruiting component Ubx2. This complex does not contain the ubiquitin ligases Hrd1/Der3 and Doa10. The existence of such a complex might point to an additional function of Dfm1 independent from ERAD.
authors.affiliation: Institut für Biochemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Stolz
authors.forename: Regina S
authors.initials: RS
authors.lastname: Schweizer
authors.forename: Antje
authors.initials: A
authors.lastname: Schäfer
authors.forename: Dieter H
authors.initials: DH
authors.lastname: Wolf
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D000074405:Valosin Containing Protein
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C098515:DER1 protein, S cerevisiae; C530209:Dfm1 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C546121:Usa1 protein, S cerevisiae; C104621:HRD1 protein, S cerevisiae; C091362:SSM4 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein