Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea.
Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea; Center for Fungal Genetic Resources, Plant Immunity Research Center, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
Fungal Genet Biol. 2020 Nov;144:103473. doi: 10.1016/j.fgb.2020.103473. Epub 2020 Sep 28.
Ubiquitination, an important process in post-translational modification, regulates various mechanisms in eukaryotes including protein degradation and interaction, cell cycle, stress response, and pathogenicity. The Skp1/Cullin/F-box and the endoplasmic reticulum-associated degradation (ERAD) complexes, RING E3 ligase complexes, are involved in ubiquitin-mediated proteolysis and protein quality control. The F-box protein has FBXO (F-box only or others), FBXW (with WD40), and FBXL (with LRR) classes depending on which interaction domain is present on the C-terminus. The ubiquitin system component cue (CUE) protein is a key factor of ERAD. However, the biological roles of FBXO and CUE proteins are largely unknown in plant pathogenic fungi including Magnaporthe oryzae. To elucidate the roles of FBXO and CUE proteins in fungal development and pathogenicity, MoFBX15 and MoCUE1 were functionally characterized in M. oryzae. Two ubiquitination-associated genes were crucial for conidiation, alkaline stress tolerance, and pathogenicity in M. oryzae. In particular, MoCUE1 was important for ER stress response and localization and translocation of cytoplasmic effectors. Moreover, ubiquitination and SUMOylation levels were decreased and transcript levels of deSUMOylation-associated genes were increased in ΔMofbx15 and ΔMocue1. This study will provide not only comprehensive understanding of the role of ubiquitination but also new insights on crosstalk between ubiquitination and SUMOylation in rice blast fungus and other fungal pathogens.
泛素化是一种重要的翻译后修饰过程，调节真核生物中的各种机制，包括蛋白质降解和相互作用、细胞周期、应激反应和致病性。Skp1/Cullin/F-box 和内质网相关降解 (ERAD) 复合物、RING E3 连接酶复合物参与泛素介导的蛋白质水解和蛋白质质量控制。F-box 蛋白根据其 C 末端存在的相互作用域分为 FBXO（仅 F-box 或其他）、FBXW（带有 WD40）和 FBXL（带有 LRR）类。泛素系统成分 cue（CUE）蛋白是 ERAD 的关键因素。然而，在包括稻瘟病菌在内的植物病原真菌中，FBXO 和 CUE 蛋白的生物学功能在很大程度上尚不清楚。为了阐明 FBXO 和 CUE 蛋白在真菌发育和致病性中的作用，在稻瘟病菌中对 MoFBX15 和 MoCUE1 进行了功能表征。两个泛素化相关基因在稻瘟病菌的分生孢子形成、耐碱性应激和致病性中至关重要。特别是，MoCUE1 对 ER 应激反应以及细胞质效应物的定位和易位很重要。此外，泛素化和 SUMO 化水平降低，ΔMofbx15 和 ΔMocue1 中去 SUMO 化相关基因的转录水平升高。这项研究不仅将提供对泛素化作用的全面理解，还将为稻瘟病菌和其他真菌病原体中泛素化和 SUMO 化之间的串扰提供新的见解。
