Madina Mst Hur, Rahman Md Saifur, Huang Xiaoqiang, Zhang Yang, Zheng Huanquan, Germain Hugo
Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, 3351 boulevard des Forges, Trois-Rivières, QC G9A 5H7, Canada.
Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
Biology (Basel). 2020 Sep 16;9(9):294. doi: 10.3390/biology9090294.
, the causal agent of leaf rust, secretes an array of effectors into the host through the haustorium to gain nutrients and suppress immunity. The precise mechanisms by which these effectors promote virulence remain unclear. To address this question, we developed a transgenic line expressing a candidate effector, Mlp124357. Constitutive expression of the effector increased plant susceptibility to pathogens. A GxxxG motif present in Mlp124357 is required for its subcellular localization at the vacuolar membrane of the plant cell, as replacement of the glycine residues with alanines led to the delocalization of Mlp124357 to the nucleus and cytoplasm. We used immunoprecipitation and mass spectrometry (MS) to identify Mlp124357 interaction partners. Only one of the putative interaction partners knock-out line caused delocalization of the effector, indicating that protein disulfide isomerase-11 (AtPDI-11) is required for the effector localization. This interaction was further confirmed by a complementation test, a yeast-two hybrid assay and a molecular modeling experiment. Moreover, localization results and infection assays suggest that AtPDI-11 act as a helper for Mlp124357. In summary, our findings established that one of effectors resides at the vacuole surface and modulates plant susceptibility.
叶锈病的病原体通过吸器向宿主分泌一系列效应蛋白，以获取营养并抑制免疫反应。这些效应蛋白促进毒力的确切机制尚不清楚。为了解决这个问题，我们构建了一个表达候选效应蛋白Mlp124357的转基因品系。效应蛋白的组成型表达增加了植物对病原体的易感性。Mlp124357中存在的GxxxG基序是其在植物细胞液泡膜上进行亚细胞定位所必需的，因为用丙氨酸取代甘氨酸残基会导致Mlp124357定位到细胞核和细胞质中。我们使用免疫沉淀和质谱（MS）来鉴定Mlp124357的相互作用伙伴。只有一个推定的相互作用伙伴敲除品系导致效应蛋白的定位异常，表明蛋白质二硫键异构酶-11（AtPDI-11）是效应蛋白定位所必需的。通过互补试验、酵母双杂交试验和分子模拟实验进一步证实了这种相互作用。此外，定位结果和感染试验表明AtPDI-11作为Mlp124357的辅助因子发挥作用。总之，我们的研究结果表明，其中一种效应蛋白定位于液泡表面并调节植物的易感性。
