期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2011
卷号：108
期号：2
页码：870-875
DOI：10.1073/pnas.1013251108
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Endoplasmic reticulum (ER)-associated degradation (ERAD) is an integral part of the ER quality-control system that removes toxic misfolded proteins via ubiquitin/proteasome-mediated degradation. Most of our knowledge on ERAD comes from biochemical and genetic studies in yeast and mammalian cells. Although ERAD is known to operate in plant cells, little is known about its molecular components and its biochemical mechanism. A genetic screen for suppressors of the Arabidopsis bri1-9, a weak dwarf mutant caused by ER retention of a structurally defective yet biochemically competent brassinosteroid (BR) receptor BRI1, resulted in identification of the EMS-mutagenized bri1 suppressor 5 (EBS5) gene that encodes an Arabidopsis homolog of the yeast Hrd3/mammlian Sel1L protein known to be involved in ERAD. Loss-of-function ebs5 mutations block the ERAD of bri1-9 and bri1-5, another ER-retained BR receptor. We showed that EBS5 complemented the ERAD defect of the yeast{Delta} hrd3 mutant and interacted with the two mutated BR receptors in plant cells. Using a reverse genetic approach, we discovered that two Arabidopsis homologs of the yeast/mammalian Hrd1, an ER membrane-localized ubiquitin ligase, function redundantly in the ERAD of bri1-9. Together, our results revealed functional roles of two conserved ERAD components in degrading mutated/misfolded receptor-like kinases in Arabidopsis.
