The Ubiquitin E3 Ligase PUB17 Positively Regulates Immunity by Targeting a Negative Regulator, KH17, for Degradation
The Ubiquitin E3 Ligase PUB17 Positively Regulates Immunity by Targeting a Negative Regulator, KH17, for Degradation
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DOI：
10.1016/j.xplc.2020.100020
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发表时间：
2020-07-13
影响因子：
10.5
通讯作者：
Birch, Paul R. J.
中科院分区：
文献类型：
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作者：
McLellan, Hazel;Chen, Kai;Birch, Paul R. J.
泛素化是一种翻译后修饰，调节植物中的许多过程。几种泛素E3连接酶通过促进不同底物的降解作为免疫的正或负调节剂。StPUB 17是一种E3连接酶，先前已显示出积极调节对细菌、真菌和卵菌的免疫力，包括晚疫病病原体致病疫霉（Phytophthora infestans）。StPUB 17的沉默促进病原体定殖并减弱Cf 4/avr 4细胞死亡。使用酵母双杂交和免疫共沉淀，我们确定了推定的K-同源性（KH）RNA结合蛋白（RBP），StKH 17，作为StPUB 17降解的候选底物。StKH 17作为免疫的负调节剂，促进致病疫霉感染并抑制特异性免疫途径。StKH 17的KH RBP结构域突变体（StKH 17（GDDG））不再能够负调节免疫力，表明RNA结合可能是StKH 17功能所需的。由于StPUB 17是泛素E3连接酶StPOB 1的已知靶标，我们揭示了E3连接酶调控级联中控制植物防御的额外步骤。
Ubiquitination is a post-translational modification that regulates many processes in plants. Several ubiquitin E3 ligases act as either positive or negative regulators of immunity by promoting the degradation of different substrates. StPUB17 is an E3 ligase that has previously been shown to positively regulate immunity to bacteria, fungi and oomycetes, including the late blight pathogen Phytophthora infestans. Silencing of StPUB17 promotes pathogen colonization and attenuates Cf4/avr4 cell death. Using yeast-2-hybrid and co-immunoprecipitation we identified the putative K-homology (KH) RNA-binding protein (RBP), StKH17, as a candidate substrate for degradation by StPUB17. StKH17 acts as a negative regulator of immunity that promotes P. infestans infection and suppresses specific immune pathways. A KH RBP domain mutant of StKH17 (StKH17(GDDG)) is no longer able to negatively regulate immunity, indicating that RNA binding is likely required for StKH17 function. As StPUB17 is a known target of the ubiquitin E3 ligase, StPOB1, we reveal an additional step in an E3 ligase regulatory cascade that controls plant defense.