Ralstonia solanacearum requires F-box-like domain-containing type III effectors to promote disease on several host plants
Ralstonia solanacearum requires F-box-like domain-containing type III effectors to promote disease on several host plants
复制标题
DOI：
10.1073/pnas.0509393103
复制
发表时间：
2006-09-26
影响因子：
11.1
通讯作者：
Genin, Stephane
中科院分区：
文献类型：
--
作者：
Angot, Aurelie;Peeters, Nemo;Genin, Stephane
植物致病性细菌Ralstonia solanacearum编码7个III型分泌系统（T3SS）效应子家族，包含一个富含亮氨酸的重复序列和一个F-box结构域。这种结构让人想起一类典型的真核蛋白，称为F-box蛋白。后者与Skp1和Cullin1亚基一起构成scf型E3泛素连接酶复合物，并控制特异性蛋白泛素化。在真核细胞中，根据多泛素链的性质，泛素标记的蛋白质要么看到它们的性质被修改，要么注定要被26S蛋白酶体降解。这条通路对植物的许多发育过程至关重要，从激素信号和花的发育到胁迫反应。在这里，我们发现这些先前描述的T3SS效应物是假定的细菌F-box蛋白，能够与19种不同的拟南芥skp1样蛋白中的一个子集相互作用，如真正的拟南芥F-box蛋白。一个7个GALA效应基因全部缺失或突变的茄红霉菌株对拟南芥不再致病，对番茄的毒力降低。此外，我们还发现GALA7是一种宿主特异性因子，是短叶紫花苜蓿（Medicago truncatula）病害所必需的。本研究结果表明，GALA T3SS效应体在茄花病害防治中起重要作用。由于F-box结构域对GALA7的毒力功能至关重要，我们假设这些效应物通过劫持其宿主scf型E3泛素连接酶来干扰其宿主泛素/蛋白酶体途径以促进疾病。
The phytopathogenic bacterium Ralstonia solanacearum encodes a family of seven type III secretion system (T3SS) effectors that contain both a leucine-rich repeat and an F-box domain. This structure is reminiscent of a class of typical eukaryotic proteins called F-box proteins. The latter, together with Skp1 and Cullin1 subunits, constitute the SCF-type E3 ubiquitin ligase complex and control specific protein ubiquitinylation. In the eukaryotic cell, depending on the nature of the polyubiquitin chain, the ubiquitin-tagged proteins either see their properties modified or are doomed for degradation by the 26S proteasome. This pathway is essential to many developmental processes in plants, ranging from hormone signaling and flower development to stress responses. Here, we show that these previously undescribed T3SS effectors are putative bacterial F-box proteins capable of interacting with a subset of the 19 different Arabidopsis Skp1-like proteins like bona fide Arabidopsis F-box proteins. A R. solanacearum strain in which all of the seven GALA effector genes have been deleted or mutated was no longer pathogenic on Arabidopsis and less virulent on tomato. Furthermore, we found that GALA7 is a host-specificity factor, required for disease on Medicago truncatula plants. Our results indicate that the GALA T3SS effectors are essential to R. solanacea-rum to control disease. Because the F-box domain is essential to the virulence function of GALA7, we hypothesize that these effectors act by hijacking their host SCF-type E3 ubiquitin ligases to interfere with their host ubiquitin/proteasome pathway to promote disease.