Intramembrane protease RHBDL4 induces ER-associated degradation of the oligosaccharyltransferase complex [article]

Julia D. Knopf, Nina Landscheidt, Cassandra L. Pegg, Benjamin L. Schulz, Nathalie Kühnle, Chao-Wei Chao, Simon Huck, Marius K. Lemberg
2019 bioRxiv   pre-print
AbstractThe Endoplasmic Reticulum (ER)-resident intramembrane rhomboid protease RHBDL4 generates metastable protein fragments and together with the ER-associated degradation (ERAD) machinery provides a clearance mechanism for aberrant and surplus proteins. However, the endogenous substrate spectrum and with that the role of RHBDL4 in physiological ERAD is mainly unknown. Here, we use quantitative proteomics to identify physiological RHBDL4 substrates. This revealed oligosacharyltransferase
more » ... ryltransferase (OST) complex subunits such as the catalytic active subunit STT3A as substrates for the RHBDL4-dependent ERAD pathway. RHBDL4-catalyzed cleavage inactivates OST subunits by triggering dislocation into the cytoplasm and subsequent proteasomal degradation. RHBDL4-catalyzed cleavage is enhanced by positive charged transmembrane residues, which are recognized by a putative negative-charged docking site at the rhomboid active site gate. RHBDL4 controls the abundance and activity of OST, suggesting a novel link between the ERAD machinery and glycosylation tuning in the ER.
doi:10.1101/850776 fatcat:o5gtooiysna7blobjljblhrlpu