Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou 510631, China.
Shenzhen Institute of Molecular Crop Design, Shenzhen 518107, China.
Plant Cell. 2024 May 29;36(6):2103-2116. doi: 10.1093/plcell/koae049.
Bacterial pathogens deliver effectors into host cells to suppress immunity. How host cells target these effectors is critical in pathogen-host interactions. SUMOylation, an important type of posttranslational modification in eukaryotic cells, plays a critical role in immunity, but its effect on bacterial effectors remains unclear in plant cells. In this study, using bioinformatic and biochemical approaches, we found that at least 16 effectors from the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 are SUMOylated by the enzyme cascade from Arabidopsis thaliana. Mutation of SUMOylation sites on the effector HopB1 enhances its function in the induction of plant cell death via stability attenuation of a plant receptor kinase BRASSINOSTEROID INSENSITIVE 1 (BRI1)-ASSOCIATED RECEPTOR KINASE 1. By contrast, SUMOylation is essential for the function of another effector, HopG1, in the inhibition of mitochondria activity and jasmonic acid signaling. SUMOylation of both HopB1 and HopG1 is increased by heat treatment, and this modification modulates the functions of these 2 effectors in different ways in the regulation of plant survival rates, gene expression, and bacterial infection under high temperatures. Therefore, the current work on the SUMOylation of effectors in plant cells improves our understanding of the function of dynamic protein modifications in plant-pathogen interactions in response to environmental conditions.
细菌病原体将效应蛋白输送到宿主细胞中以抑制免疫。宿主细胞靶向这些效应蛋白的方式在病原体-宿主相互作用中至关重要。SUMOylation 是真核细胞中一种重要的翻译后修饰类型，在免疫中发挥着关键作用，但在植物细胞中，其对细菌效应蛋白的影响尚不清楚。在这项研究中，我们使用生物信息学和生化方法发现，至少 16 种来自细菌病原体丁香假单胞菌 pv.番茄 DC3000 的效应蛋白被拟南芥中的酶级联 SUMOylated。效应蛋白 HopB1 上 SUMOylation 位点的突变增强了其通过衰减植物受体激酶 BRASSINOSTEROID INSENSITIVE 1（BRI1）-ASSOCIATED RECEPTOR KINASE 1 的稳定性诱导植物细胞死亡的功能。相比之下，SUMOylation 是另一种效应蛋白 HopG1 抑制线粒体活性和茉莉酸信号所必需的。热处理会增加 HopB1 和 HopG1 的 SUMOylation，这种修饰以不同的方式调节这 2 种效应蛋白在高温下调节植物存活率、基因表达和细菌感染的功能。因此，目前对植物细胞中效应蛋白 SUMOylation 的研究增进了我们对环境条件下动态蛋白质修饰在植物-病原体相互作用中的功能的理解。
