Medicago falcata MfSTMIR, an E3 ligase of endoplasmic reticulum‐associated degradation, is involved in salt stress response. (6th March 2019)

• Record Type: Journal Article
• Authors: Zhang, Rongxue; Chen, Hong; Duan, Mei; Zhu, Fugui; Wen, Jiangqi; Dong, Jiangli; Wang, Tao
• Is Part Of: Plant journal. Volume 98:Number 4(2019)
• Page Start: 680
• Page End: 696
• Publication Date: 2019-03-06
• Subjects: endoplasmic reticulum‐associated degradation -- unfolded protein response -- endoplasmic reticulum stress -- salt stress -- Medicago; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.14265
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: Recent studies on E3 of endoplasmic reticulum (ER)‐associated degradation (ERAD) in plants have revealed homologs in yeast and animals. However, it remains unknown whether the plant ERAD system contains a plant‐specific E3 ligase. Here, we report that MfSTMIR, which encodes an ER‐membrane‐localized RING E3 ligase that is highly conserved in leguminous plants, plays essential roles in the response of ER and salt stress in Medicago . MfSTMIR expression was induced by salt and tunicamycin (Tm). mtstmir loss‐of‐function mutants displayed impaired induction of the ER stress‐responsive genes BiP1/2 and BiP3 under Tm treatment and sensitivity to salt stress. MfSTMIR promoted the degradation of a known ERAD substrate, CPY*. MfSTMIR interacted with the ERAD‐associated ubiquitin‐conjugating enzyme MtUBC32 and Sec61‐translocon subunit MtSec61γ. MfSTMIR did not affect MtSec61γ protein stability. Our results suggest that the plant‐specific E3 ligase MfSTMIR participates in the ERAD pathway by interacting with MtUBC32 and MtSec61γ to relieve ER stress during salt stress. Significance Statement: Endoplasmic reticulum (ER)‐associated protein degradation (ERAD) is an essential mechanism for misfolded protein degradation. Recent studies on the E3 ubiquitin ligase of ERAD have focused on yeast and animals; there have been only a few reports in plants. We report that MfSTMIR, an ER‐membrane‐localized RING E3 ubiquitin ligase, is an active ERAD component. MfSTMIR interacts with MtUBC32 and MtSec61γ, which plays an essential role in the ER and salt stress response of Medicago .