Identification of an Htm1 (EDEM)-dependent, Mns1-independent endoplasmic reticulum-associated degradation (ERAD) pathway in Saccharomyces cerevisiae: Application of a novel assay for glycoprotein ERAD

Akira Hosomi, Kaori Tanabe, Hiroto Hirayama, Ikjin Kim, Hai Rao, Tadashi Suzuki

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Endoplasmic reticulum (ER)-associated degradation (ERAD) is a quality control system for newly synthesized proteins in the ER; nonfunctional proteins, which fail to form their correct folding state, are then degraded. The cytoplasmic peptide:N-glycanase is a deglycosylating enzyme that is involved in the ERAD and releases N-glycans from misfolded glycoproteins/glycopeptides. We have previously identified a mutant plant toxin protein, RTA (ricin A-chain nontoxic mutant), as the first in vivo Png1 (the cytoplasmic peptide:N-glycanase in Saccharomyces cerevisiae)-dependent ERAD substrate. Here, we report a new genetic device to assay the Png1-dependent ERAD pathway using the new model protein designated RTL (RTA-transmembrane-Leu2). Our extensive studies using different yeast mutants identified various factors involved in RTL degradation. The degradation of RTA/RTL was independent of functional Sec61 but was dependent on Der1. Interestingly, ER-mannosidase Mns1 was not involved in RTA degradation, but it was dependent on Htm1 (ERAD-related α-mannosidase in yeast) and Yos9 (a putative degradation lectin), indicating that mannose trimming by Mns1 is not essential for efficient ERAD of RTA/RTL. The newly established RTL assay will allow us to gain further insight into the mechanisms involved in the Png1-dependent ERAD-L pathway.

Original languageEnglish (US)
Pages (from-to)24324-24334
Number of pages11
JournalJournal of Biological Chemistry
Volume285
Issue number32
DOIs
StatePublished - Aug 6 2010

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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