Hotson Andrew, Chosed Renee, Shu Hongjun, Orth Kim, Mudgett Mary Beth
Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA.
Mol Microbiol. 2003 Oct;50(2):377-89. doi: 10.1046/j.1365-2958.2003.03730.x.
Xanthomonas campestris pathovar vesicatoria (Xcv) uses the type III secretion system (TTSS) to inject effector proteins into cells of Solanaceous plants during pathogenesis. A number of Xcv TTSS effectors have been identified; however, their function in planta remains elusive. Here, we provide direct evidence for a functional role for a phytopathogenic bacterial TTSS effector in planta by demonstrating that the Xcv effector XopD encodes an active cysteine protease with plant-specific SUMO substrate specificity. XopD is injected into plant cells by the TTSS during Xcv pathogenesis, translocated to subnuclear foci and hydrolyses SUMO-conjugated proteins in vivo. Our studies suggest that XopD mimics endogenous plant SUMO isopeptidases to interfere with the regulation of host proteins during Xcv infection.
野油菜黄单胞菌疮痂致病变种（Xcv）在致病过程中利用III型分泌系统（TTSS）将效应蛋白注入茄科植物细胞。已鉴定出多种Xcv TTSS效应蛋白；然而，它们在植物中的功能仍不清楚。在这里，我们通过证明Xcv效应蛋白XopD编码一种具有植物特异性SUMO底物特异性的活性半胱氨酸蛋白酶，为植物致病细菌TTSS效应蛋白在植物中的功能作用提供了直接证据。在Xcv致病过程中，XopD通过TTSS注入植物细胞，转移至核内小体并在体内水解SUMO共轭蛋白。我们的研究表明，XopD模拟内源性植物SUMO异肽酶，在Xcv感染期间干扰宿主蛋白的调控。
