The Arabidopsis U-box E3 ubiquitin ligase PUB30 negatively regulates salt tolerance by facilitating BRI1 kinase inhibitor 1 (BKI1) degradation
The Arabidopsis U-box E3 ubiquitin ligase PUB30 negatively regulates salt tolerance by facilitating BRI1 kinase inhibitor 1 (BKI1) degradation
复制标题
拟南芥 U-box E3 泛素连接酶 PUB30 通过促进 BRI1 激酶抑制剂 1 (BKI1) 降解负向调节耐盐性
DOI：
10.1111/pce.13064
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发表时间：
2017
影响因子：
7.3
通讯作者：
Li Xueyong
中科院分区：
文献类型：
--
作者：
Zhang Ming;Zhao Jinfeng;Li Long;Gao Yanan;Zhao Linlin;Patil Suyash Bhimgonda;Fang Jingjing;Zhang Wenhui;Yang Yuhong;Li Ming;Li Xueyong
拟南芥U-box E3泛素连接酶在泛素/26S蛋白酶体介导的蛋白质降解途径中起着重要作用。近年来，PUB30以不依赖于脱落酸(ABA)的方式参与了种子萌发过程中的盐胁迫反应，但其分子机制尚不清楚。在此，我们发现pub30突变体在种子萌发过程中对盐胁迫的耐受性更强，而与其最接近的同源突变体PUB31对盐胁迫表现出轻微的敏感性。PUB30在体外具有E3泛素连接酶活性。PUB30在体外和体内都能与BRI1激酶抑制因子1(BKI1)特异性地相互作用，BKI1在油菜素类固醇信号转导中起双重作用。我们发现BKI1蛋白被26S蛋白酶体泛素化和降解。与野生型相比，pub30-1突变体中BKI1的降解速度减慢。BKI1突变体对盐敏感，而过量表达BKI1的转基因植株表现出耐盐表型。这些结果表明，PUB30可能通过调节BKI1和油菜素类固醇信号的降解来负向调节拟南芥的耐盐性。
TheArabidopsisU‐box E3 ubiquitin ligases play an important role in the ubiquitin/26S proteasome‐mediated protein degradation pathway. Recently, PUB30 has been reported to participate in the salt stress response during seed germination stage in abscisic acid (ABA)‐independent manner, but the molecular mechanism remains to be elucidated. Here, we displayed that thepub30mutant was more tolerant to salt stress during seed germination, whereas the mutant of its closest homologue PUB31 showed mild sensitivity to salt stress. PUB30 exhibited E3 ubiquitin ligase activity in vitro. PUB30 specifically interacted with BRI1 kinase inhibitor 1 (BKI1), a regulator playing dual roles in brassinosteroids signaling, in vitro and in vivo. We found that BKI1 protein was ubiquitinated and degraded by the 26S proteasome. The degradation of BKI1 was slowed down in thepub30‐1mutant compared with that in the wild type. Thebki1mutant was sensitive to salt, whereas the transgenic plants overexpressingBKI1showed salt tolerant phenotype. All these results indicate that PUB30 negatively regulates salt tolerance probably through regulating the degradation of BKI1 and brassinosteroids signaling inArabidopsis.