Zhang Hao, Liu Jinling, He Feng, Wang Zhilong, Ning Yuese, Wang Guo-Liang
a Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization; Hunan Agricultural University ; Changsha Hunan , China.
Plant Signal Behav. 2015;10(8):e1039212. doi: 10.1080/15592324.2015.1039212.
Ubiquitin-mediated protein degradation is involved in various cellular processes including plant-microbe interactions and defense responses. Although there are many E3 ubiquitin ligases in rice, the functions of their targets in defense responses are unclear. We recently found that SPIN6 (SPL11-interacting Protein 6) is a Rho GTPase-activating protein and acts as the target of the E3 ligase SPL11, a negative regulator of plant cell death and innate immunity. Our results showed that SPIN6 serves as a link between the SPL11-mediated ubiquitination pathway and the OsRac1-associated defense system. Here, we show that SPIN6 interacts with OsHUB1 and OsHUB2, the homologous proteins of Arabidopsis RING finger E3 ligases HUB1 and HUB2. OsHub1 and OsHub2 are down-regulated in the Spin6 RNAi plants and during the compatible interaction between rice and Magnaporthe oryzae. OsHub1 and OsHub2 are induced by hormone treatments. Like HUB1 and HUB2 in Arabidopsis, OsHUB1 and OsHUB2 in rice form homo- and hetero-dimers. Our results suggest that OsHUB1 and OsHUB2 may be associated with the SPIN6/OsRac1 pathway in rice immunity.
泛素介导的蛋白质降解参与包括植物与微生物相互作用和防御反应在内的各种细胞过程。尽管水稻中有许多E3泛素连接酶，但其靶标在防御反应中的功能尚不清楚。我们最近发现，SPIN6（与SPL11相互作用的蛋白6）是一种Rho GTPase激活蛋白，作为E3连接酶SPL11的靶标，而SPL11是植物细胞死亡和先天免疫的负调控因子。我们的结果表明，SPIN6是SPL11介导的泛素化途径与OsRac1相关防御系统之间的一个连接。在此，我们表明SPIN6与拟南芥RING指E3连接酶HUB1和HUB2的同源蛋白OsHUB1和OsHUB2相互作用。在Spin6 RNAi植物中以及在水稻与稻瘟病菌的亲和性互作过程中，OsHub1和OsHub2表达下调。OsHub1和OsHub2受激素处理诱导。与拟南芥中的HUB1和HUB2一样，水稻中的OsHUB1和OsHUB2形成同二聚体和异二聚体。我们的结果表明，OsHUB1和OsHUB2可能与水稻免疫中的SPIN6/OsRac1途径相关。
