Format

Send to

Choose Destination
Cell. 2016 Jul 14;166(2):394-407. doi: 10.1016/j.cell.2016.05.048. Epub 2016 Jun 16.

Autoubiquitination of the Hrd1 Ligase Triggers Protein Retrotranslocation in ERAD.

Author information

1
Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA. Electronic address: ryan_baldridge@hms.harvard.edu.
2
Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA. Electronic address: tom_rapoport@hms.harvard.edu.

Abstract

Misfolded proteins of the ER are retrotranslocated to the cytosol, where they are polyubiquitinated, extracted from the membrane, and degraded by the proteasome. To investigate how the ER-associated Degradation (ERAD) machinery can accomplish retrotranslocation of a misfolded luminal protein domain across a lipid bilayer, we have reconstituted retrotranslocation with purified S. cerevisiae proteins, using proteoliposomes containing the multi-spanning ubiquitin ligase Hrd1. Retrotranslocation of the luminal domain of a membrane-spanning substrate is triggered by autoubiquitination of Hrd1. Substrate ubiquitination is a subsequent event, and the Cdc48 ATPase that completes substrate extraction from the membrane is not required for retrotranslocation. Ubiquitination of lysines in Hrd1's RING-finger domain is required for substrate retrotranslocation in vitro and for ERAD in vivo. Our results suggest that Hrd1 forms a ubiquitin-gated protein-conducting channel.

PMID:
27321670
PMCID:
PMC4946995
DOI:
10.1016/j.cell.2016.05.048
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center