Structure of HrcQB-C, a conserved component of the bacterial type III secretion systems
Structure of HrcQB-C, a conserved component of the bacterial type III secretion systems
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DOI：
10.1073/pnas.0304579101
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发表时间：
2004-01-06
影响因子：
11.1
通讯作者：
Kokkinidis, M
中科院分区：
文献类型：
--
作者：
Fadouloglou, VE;Tampakaki, AP;Kokkinidis, M
III型分泌系统使植物和动物细菌病原体能够将毒力蛋白递送到真核宿主细胞的胞质溶胶中，从而在哺乳动物中引起广谱疾病，包括菌血症、败血症、伤寒和腺鼠疫，以及在植物中引起局部病变、系统性萎蔫和枯萎。此外，细菌鞭毛的生物发生也需要III型分泌系统。HrcQ（B）蛋白是丁香假单胞菌分泌器的组成部分，在所有III型系统中具有同源物，具有可变的N末端和保守的C末端结构域（HrcQ（B）-C）。在这里，我们报告的晶体结构的HrcQ（B）-C和显示，这个域保留了全长蛋白质的能力，与其他III型组件。序列保守模式的3D分析揭示了可能参与蛋白质-蛋白质相互作用的两个残基簇。基于HrcQ（B）与鞭毛同源物之间的相似性，我们推测HrcQ（B）-C参与了一个C环样组装体的形成。
Type III secretion systems enable plant and animal bacterial pathogens to deliver virulence proteins into the cytosol of eukaryotic host cells, causing a broad spectrum of diseases including bacteremia, septicemia, typhoid fever, and bubonic plague in mammals, and localized lesions, systemic wilting, and blights in plants. In addition, type III secretion systems are also required for biogenesis of the bacterial flagellum. The HrcQ(B) protein, a component of the secretion apparatus of Pseudomonas syringae with homologues in all type III systems, has a variable N-terminal and a conserved C-terminal domain (HrcQ(B)-C). Here, we report the crystal structure of HrcQ(B)-C and show that this domain retains the ability of the full-length protein to interact with other type III components. A 3D analysis of sequence conservation patterns reveals two clusters of residues potentially involved in protein-protein interactions. Based on the analogies between HrcQ(B) and its flagellum homologues, we propose that HrcQ(B)-C participates in the formation of a C-ring-like assembly.