Disruption of the Rickettsia rickettsii Sca2 Autotransporter Inhibits Actin-Based Motility
Disruption of the Rickettsia rickettsii Sca2 Autotransporter Inhibits Actin-Based Motility
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DOI：
10.1128/iai.00100-10
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发表时间：
2010-05-01
影响因子：
3.1
通讯作者：
Hackstadt, Ted
中科院分区：
文献类型：
--
作者：
Kleba, Betsy;Clark, Tina R.;Hackstadt, Ted
立克次氏体是落基山斑疹热的病原体，在感染细胞的胞质溶胶内复制，并使用基于肌动蛋白的运动性在细胞间和细胞内传播。虽然肌动蛋白尾部的超微结构和与之相关的宿主蛋白与李斯特菌或志贺氏菌不同，但关于其组织中涉及的立克次体蛋白的了解相对较少。在这里，我们使用了随机转座子诱变R。立克次氏体以产生小空斑突变体，该突变体在基于肌动蛋白的运动性方面有缺陷，并且不像斑点热群立克次氏体的特征那样直接从细胞传播到细胞。该突变株的转座子插入位点位于Sca 2内，Sca 2是大型自转运蛋白家族的成员。Sca 2表现出几个功能，提示其在肌动蛋白为基础的运动的明显作用。它展示了一个N-末端分泌信号肽，一个C-末端预测的自转运蛋白结构域，多达四个预测的黄蜂同源性2（WH 2）结构域，和两个富含脯氨酸的结构域，一个与真核formin相似。在豚鼠感染模型中，Sca 2突变体没有引起发热，表明Sca 2和肌动蛋白为基础的运动性是斑点热群立克次体的毒力因子。
Rickettsii rickettsii, the etiologic agent of Rocky Mountain spotted fever, replicates within the cytosol of infected cells and uses actin-based motility to spread inter- and intracellularly. Although the ultrastructure of the actin tail and host proteins associated with it are distinct from those of Listeria or Shigella, comparatively little is known regarding the rickettsial proteins involved in its organization. Here, we have used random transposon mutagenesis of R. rickettsii to generate a small-plaque mutant that is defective in actin-based motility and does not spread directly from cell to cell as is characteristic of spotted fever group rickettsiae. The transposon insertion site of this mutant strain was within Sca2, a member of a family of large autotransporter proteins. Sca2 exhibits several features suggestive of its apparent role in actin-based motility. It displays an N-terminal secretory signal peptide, a C-terminal predicted autotransporter domain, up to four predicted Wasp homology 2 (WH2) domains, and two proline-rich domains, one with similarity to eukaryotic formins. In a guinea pig model of infection, the Sca2 mutant did not elicit fever, suggesting that Sca2 and actin-based motility are virulence factors of spotted fever group rickettsiae.