Li Zhiqiang, Ding Bo, Zhou Xueping, Wang Guo-Liang
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China and College of Agronomy, Hunan Agricultural University, Changsha, Hunan, China.
PLoS Pathog. 2017 Jan 12;13(1):e1006157. doi: 10.1371/journal.ppat.1006157. eCollection 2017 Jan.
Programmed cell death (PCD) mediated by mitochondrial processes has emerged as an important mechanism for plant development and responses to abiotic and biotic stresses. However, the role of translocation of cytochrome c from the mitochondria to the cytosol during PCD remains unclear. Here, we demonstrate that the rice dynamin-related protein 1E (OsDRP1E) negatively regulates PCD by controlling mitochondrial structure and cytochrome c release. We used a map-based cloning strategy to isolate OsDRP1E from the lesion mimic mutant dj-lm and confirmed that the E409V mutation in OsDRP1E causes spontaneous cell death in rice. Pathogen inoculation showed that dj-lm significantly enhances resistance to fungal and bacterial pathogens. Functional analysis of the E409V mutation showed that the mutant protein impairs OsDRP1E self-association and formation of a higher-order complex; this in turn reduces the GTPase activity of OsDRP1E. Furthermore, confocal microscopy showed that the E409V mutation impairs localization of OsDRP1E to the mitochondria. The E409V mutation significantly affects the morphogenesis of cristae in mitochondria and causes the abnormal release of cytochrome c from mitochondria into cytoplasm. Taken together, our results demonstrate that the mitochondria-localized protein OsDRP1E functions as a negative regulator of cytochrome c release and PCD in plants.
由线粒体过程介导的程序性细胞死亡（PCD）已成为植物发育以及对非生物和生物胁迫响应的重要机制。然而，在PCD过程中细胞色素c从线粒体转运到细胞质中的作用仍不清楚。在此，我们证明水稻动力相关蛋白1E（OsDRP1E）通过控制线粒体结构和细胞色素c释放来负向调节PCD。我们采用图位克隆策略从类病变突变体dj-lm中分离出OsDRP1E，并证实OsDRP1E中的E409V突变导致水稻自发细胞死亡。病原菌接种表明，dj-lm显著增强了对真菌和细菌病原体的抗性。对E409V突变的功能分析表明，突变蛋白损害了OsDRP1E的自缔合和高阶复合物的形成；这进而降低了OsDRP1E的GTP酶活性。此外，共聚焦显微镜显示E409V突变损害了OsDRP1E在线粒体上的定位。E409V突变显著影响线粒体嵴的形态发生，并导致细胞色素c从线粒体异常释放到细胞质中。综上所述，我们的结果表明，定位于线粒体的蛋白OsDRP1E在植物中作为细胞色素c释放和PCD的负调节因子发挥作用。
