In vivo structure of the Legionella type II secretion system by electron cryotomography
In vivo structure of the Legionella type II secretion system by electron cryotomography
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DOI：
10.1038/s41564-019-0603-6
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发表时间：
2019-12-01
影响因子：
28.3
通讯作者：
Jensen, Grant J.
中科院分区：
文献类型：
--
作者：
Ghosal, Debnath;Kim, Ki Woo;Jensen, Grant J.
II型分泌系统（T2 SS）是一种多蛋白质跨膜组装体，可将多种毒力因子、酶和效应物易位通过许多革兰氏阴性菌的外膜（1-3）。在这里，使用电子cryotomography和subtomogram平均方法，我们揭示了在体内结构的完整的T2 SS成像内的人类病原体嗜肺军团菌。虽然T2 SS与进化上相关的IV型菌毛（T4 P）系统（4，5）只有有限的序列和组分同源性，但我们表明它们的整体结构非常相似。尽管有相似之处，但也有差异，包括例如T2 SS-ATP酶复合物通常存在但与内膜分离，T2 SS具有长得多的周质前庭，并且它具有短寿命的柔性假纤毛。将组件的原子模型放入我们的电子冷冻断层扫描图中，产生了完整的T2 SS的完整结构模型，该模型提供了对其组件的结构和功能，其在细胞包膜内的位置以及其不同亚复合物之间的相互作用的见解。
The type II secretion system (T2SS) is a multiprotein envelope-spanning assembly that translocates a wide range of virulence factors, enzymes and effectors through the outer membrane of many Gram-negative bacteria(1-3). Here, using electron cryotomography and subtomogram averaging methods, we reveal the in vivo structure of an intact T2SS imaged within the human pathogen Legionella pneumophila. Although the T2SS has only limited sequence and component homology with the evolutionarily related type IV pilus (T4P) system(4,5), we show that their overall architectures are remarkably similar. Despite similarities, there are also differences, including, for example, that the T2SS-ATPase complex is usually present but disengaged from the inner membrane, the T2SS has a much longer periplasmic vestibule and it has a short-lived flexible pseudopilus. Placing atomic models of the components into our electron cryotomography map produced a complete architectural model of the intact T2SS that provides insights into the structure and function of its components, its position within the cell envelope and the interactions between its different subcomplexes.