The RING-Type E3 Ligase XBAT35.2 Is Involved in Cell Death Induction and Pathogen Response
The RING-Type E3 Ligase XBAT35.2 Is Involved in Cell Death Induction and Pathogen Response
复制标题
DOI：
10.1104/pp.17.01071
复制
发表时间：
2017-11-01
期刊：
影响因子：
7.4
通讯作者：
Stone, Sophia L.
中科院分区：
文献类型：
--
作者：
Liu, Hongxia;Ravichandran, Sridhar;Stone, Sophia L.
XBAT35属于拟南芥（Arabidopsis thaliana）RING型E3的亚家族，其在结构域结构上与水稻（Oryza sativa）防御蛋白XA 21结合蛋白3相似。XBAT35转录物经过选择性剪接产生两种蛋白质同种型，XBAT35.1和XBAT35.2。在这里，我们证明了XBAT35.2主要定位于高尔基体，并参与细胞死亡诱导和病原体反应。发现当在烟草（本氏烟草（Nicotiana benthamiana））叶中过表达时，XBAT 35.2而不是XBAT 35.1触发细胞死亡，并且以需要其RING结构域的方式这样做。XBAT35基因功能的丧失破坏了植物防御病原体攻击的能力，而XBAT35.2的过表达增强了对病原体的抗性。XBAT35.2被发现是不稳定的，并促进其自身的降解，这表明自我调节。接种的细菌病原体假单胞菌番茄致病变种DC3000的毒力和无毒力菌株的结果在泛素化的XBAT 35.2的水平急剧下降和E3的丰度增加。这意味着病原体感染抑制了XBAT 35.2的自我调节，并稳定了E3。与防御病原体的作用一致，XBAT 35.2与植物中的防御相关加速细胞死亡11（ACD 11）相互作用，并在无细胞降解试验中促进ACD 11的蛋白酶体依赖性周转。根据稳定的XBAT 35.2的调节，泛素化ACD 11的水平显著增加，并且在病原体感染后ACD 11的丰度降低。此外，用蛋白酶体抑制剂处理转基因幼苗导致ACD 11的积累，证实了蛋白酶体依赖性降解。总的来说，这些结果突出了XBAT 35.2在细胞死亡诱导和防御病原体中的新作用。
XBAT35 belongs to a subfamily of Arabidopsis (Arabidopsis thaliana) RING-type E3s that are similar in domain architecture to the rice (Oryza sativa) XA21 Binding Protein3, a defense protein. The XBAT35 transcript undergoes alternative splicing to produce two protein isoforms, XBAT35.1 and XBAT35.2. Here, we demonstrate that XBAT35.2 localizes predominantly to the Golgi and is involved in cell death induction and pathogen response. XBAT35.2, but not XBAT35.1, was found to trigger cell death when overexpressed in tobacco (Nicotiana benthamiana) leaves and does so in a manner that requires its RING domain. Loss of XBAT35 gene function disrupts the plant's ability to defend against pathogen attack, whereas overexpression of XBAT35.2 enhances resistance to pathogens. XBAT35.2 was found to be unstable and promotes its own degradation, suggesting self-regulation. Inoculation with virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae pv tomato DC3000 results in a drastic reduction in the levels of ubiquitinated XBAT35.2 and an increase in the abundance of the E3. This implies that pathogen infection prohibits XBAT35.2 self-regulation and stabilizes the E3. In agreement with a role in defending against pathogens, XBAT35.2 interacts with defense-related Accelerated Cell Death11 (ACD11) in planta and promotes the proteasome-dependent turnover of ACD11 in cell-free degradation assays. In accordance with regulation by a stabilized XBAT35.2, the levels of ubiquitinated ACD11 increased considerably, and the abundance of ACD11 was reduced following pathogen infection. In addition, treatment of transgenic seedlings with a proteasome inhibitor results in the accumulation of ACD11, confirming proteasome-dependent degradation. Collectively, these results highlight a novel role for XBAT35.2 in cell death induction and defense against pathogens.