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EMR, a cytosolic‐abundant ring finger E3 ligase, mediates ER‐associated protein degradation in Arabidopsis
Author(s) -
Park Joung Hun,
Kang Chang Ho,
Nawkar Ganesh M.,
Lee Eun Seon,
Paeng Seol Ki,
Chae Ho Byoung,
Chi Yong Hun,
Kim Woe Yeon,
Yun DaeJin,
Lee Sang Yeol
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15279
Subject(s) - endoplasmic reticulum associated protein degradation , ubiquitin ligase , arabidopsis , endoplasmic reticulum , ring finger , unfolded protein response , biology , microbiology and biotechnology , protein degradation , subcellular localization , cytosol , ubiquitin , rna interference , biochemistry , mutant , cytoplasm , gene , rna , enzyme
Summary Investigation of the endoplasmic reticulum‐associated degradation (ERAD) system in plants led to the identification of ERAD‐mediating RING finger protein (EMR) as a plant‐specific ERAD E3 ligase from Arabidopsis . EMR was significantly up‐regulated under endoplasmic reticulum (ER) stress conditions. The EMR protein purified from bacteria displayed high E3 ligase activity, and tobacco leaf‐produced EMR mediated mildew resistance locus O‐12 (MLO12) degradation in a proteasome‐dependent manner. Subcellular localization and coimmunoprecipitation analyses showed that EMR forms a complex with ubiquitin‐conjugating enzyme 32 (UBC32) as a cytosolic interaction partner. Mutation of EMR and RNA interference (RNAi) increased the tolerance of plants to ER stress. EMR RNAi in the bri1‐5 background led to partial recovery of the brassinosteroid (BR)‐insensitive phenotypes as compared with the original mutant plants and increased ER stress tolerance. The presented results suggest that EMR is involved in the plant ERAD system that affects BR signaling under ER stress conditions as a novel Arabidopsis ring finger E3 ligase mainly present in cytosol while the previously identified ERAD E3 components are typically membrane‐bound proteins.