Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea.
Center for Fungal Genetic Resources, Plant Genomics and Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, South Korea.
Mol Plant Pathol. 2018 Sep;19(9):2134-2148. doi: 10.1111/mpp.12687. Epub 2018 Jul 17.
Amongst the various post-translational modifications (PTMs), SUMOylation is a conserved process of attachment of a small ubiquitin-related modifier (SUMO) to a protein substrate in eukaryotes. This process regulates many important biological mechanisms, including transcriptional regulation, protein stabilization, cell cycle, DNA repair and pathogenesis. However, the functional role of SUMOylation is not well understood in plant-pathogenic fungi, including the model fungal pathogen Magnaporthe oryzae. In this study, we elucidated the roles of four SUMOylation-associated genes that encode one SUMO protein (MoSMT3), two E1 enzymes (MoAOS1 and MoUBA2) and one E2 enzyme (MoUBC9) in fungal development and pathogenicity. Western blot assays showed that SUMO modification was abolished in all deletion mutants. MoAOS1 and MoUBA2 were mainly localized in the nucleus, whereas MoSMT3 and MoUBC9 were localized in both the nucleus and cytoplasm. However, the four SUMOylation-associated proteins were predominantly localized in the nucleus under oxidative stress conditions. Deletion mutants for each of the four genes were viable, but showed significant defects in mycelial growth, conidiation, septum formation, conidial germination, appressorium formation and pathogenicity. Several proteins responsible for conidiation were predicted to be SUMOylated, suggesting that conidiation is controlled at the post-translational level by SUMOylation. In addition to infection-related development, SUMOylation also played important roles in resistance to nutrient starvation, DNA damage and oxidative stresses. Therefore, SUMOylation is required for infection-related fungal development, stress responses and pathogenicity in M. oryzae. This study provides new insights into the role of SUMOylation in the molecular mechanisms of pathogenesis of the rice blast fungus and other plant pathogens.
在各种翻译后修饰（PTMs）中，SUMO 化是真核生物中一种将小泛素相关修饰物（SUMO）连接到蛋白质底物上的保守过程。这个过程调节着许多重要的生物学机制，包括转录调控、蛋白质稳定、细胞周期、DNA 修复和发病机制。然而，SUMO 化在植物病原真菌中的功能作用，包括模式真菌病原体稻瘟病菌，还没有得到很好的理解。在这项研究中，我们阐明了四个 SUMO 化相关基因的作用，这些基因编码一个 SUMO 蛋白（MoSMT3）、两个 E1 酶（MoAOS1 和 MoUBA2）和一个 E2 酶（MoUBC9），它们在真菌发育和致病性中发挥作用。Western blot 分析表明，所有缺失突变体中的 SUMO 修饰都被消除了。MoAOS1 和 MoUBA2 主要定位于核内，而 MoSMT3 和 MoUBC9 则定位于核内和细胞质中。然而，在氧化应激条件下，这四种 SUMO 化相关蛋白主要定位于核内。四个基因的缺失突变体都是可行的，但在菌丝生长、分生孢子形成、隔膜形成、分生孢子萌发、附着胞形成和致病性方面都有明显缺陷。几个负责分生孢子形成的蛋白质被预测为 SUMO 化，这表明分生孢子形成是由 SUMO 化在翻译后水平上控制的。除了与感染相关的发育外，SUMO 化在对营养饥饿、DNA 损伤和氧化应激的抗性中也发挥着重要作用。因此，SUMO 化是稻瘟病菌感染相关真菌发育、应激反应和致病性所必需的。这项研究为 SUMO 化在稻瘟病菌和其他植物病原物发病机制中的分子机制提供了新的见解。
