Title: The Dfm1 Derlin Is Required for ERAD Retrotranslocation of Integral Membrane Proteins.
Authors: Neal, Sonya; Jaeger, Philipp A; Duttke, Sascha H; Benner, Christopher; K Glass, Christopher; Ideker, Trey; Hampton, Randolph Y
Published In Mol Cell, (2018 01 18)
Abstract: Endoplasmic reticulum (ER)-associated degradation (ERAD) removes misfolded proteins from the ER membrane and lumen by the ubiquitin-proteasome pathway. Retrotranslocation of ubiquitinated substrates to the cytosol is a universal feature of ERAD that requires the Cdc48 AAA-ATPase. Despite intense efforts, the mechanism of ER exit, particularly for integral membrane (ERAD-M) substrates, has remained unclear. Using a self-ubiquitinating substrate (SUS), which undergoes normal retrotranslocation independently of known ERAD factors, and the new SPOCK (single plate orf compendium kit) micro-library to query all yeast genes, we found the rhomboid derlin Dfm1 was required for retrotranslocation of both HRD and DOA ERAD pathway integral membrane substrates. Dfm1 recruited Cdc48 to the ER membrane with its unique SHP motifs, and it catalyzed substrate extraction through its conserved rhomboid motifs. Surprisingly, dfm1Δ can undergo rapid suppression, restoring wild-type ERAD-M. This unexpected suppression explained earlier studies ruling out Dfm1, and it revealed an ancillary ERAD-M retrotranslocation pathway requiring Hrd1.
PubMed ID: 29351849
MeSH Terms: Adenosine Triphosphatases/metabolism; Cell Cycle Proteins/metabolism; Cytosol/metabolism; Endoplasmic Reticulum-Associated Degradation/physiology; Endoplasmic Reticulum/metabolism; Membrane Proteins/metabolism*; Membrane Proteins/physiology; Proteasome Endopeptidase Complex/metabolism; Saccharomyces cerevisiae Proteins/metabolism*; Saccharomyces cerevisiae/metabolism; Ubiquitin-Protein Ligases/metabolism; Ubiquitin/metabolism; Ubiquitination; Valosin Containing Protein/metabolism