Allele-Specific Suppression of a Defective Brassinosteroid Receptor Reveals a Physiological Role of UGGT in ER Quality Control

Hua Jin, Zhenyan Yan, Kyoung Hee Nam, Jianming Li*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

153 Citations (Scopus)

Abstract

UDP-glucose:glycoprotein glucosyltransferase (UGGT) is a presumed folding sensor of protein quality control in the endoplasmic reticulum (ER). Previous biochemical studies with nonphysiological substrates revealed that UGGT can glucosylate nonnative glycoproteins by recognizing subtle folding defects; however, its physiological function remains undefined. Here, we show that mutations in the Arabidopsis EBS1 gene suppressed the growth defects of a brassinosteroid (BR) receptor mutant, bri1-9, in an allele-specific manner by restoring its BR sensitivity. Using a map-based cloning strategy, we discovered that EBS1 encodes the Arabidopsis homolog of UGGT. We demonstrated that bri1-9 is retained in the ER through interactions with several ER chaperones and that ebs1 mutations significantly reduce the stringency of the retention-based ER quality control, allowing export of the structurally imperfect yet biochemically competent bri1-9 to the cell surface for BR perception. Thus, our discovery provides genetic support for a physiological role of UGGT in high-fidelity ER quality control.

Original languageEnglish
Pages (from-to)821-830
Number of pages10
JournalMolecular Cell
Volume26
Issue number6
Early online date21 Jun 2007
DOIs
Publication statusPublished - Jun 2007

Scopus Subject Areas

  • Molecular Biology
  • Cell Biology

User-Defined Keywords

  • proteins

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