Structure of the Pseudomonas aeruginosa Type IVa Pilus Secretin at 7.4 Å
Structure of the Pseudomonas aeruginosa Type IVa Pilus Secretin at 7.4 Å
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DOI：
10.1016/j.str.2016.08.007
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发表时间：
2016-10-04
期刊：
影响因子：
5.7
通讯作者：
Howell, P. Lynne
中科院分区：
文献类型：
--
作者：
Koo, Jason;Lamers, Ryan P.;Howell, P. Lynne
IVA型菌毛(T4aP)是细菌的毒力因子。T4aP通过同源低聚分泌素穿过革兰氏阴性菌的外膜。我们提出了7.4埃的铜绿假单胞菌PilQ分泌素的冷冻电子显微镜结构。外周和内部特征表明，促胰液素由14个亚基组成，具有C7对称性。通道是一个带肋的圆柱体，具有中心外周辐条和在周质侧关闭的中央门。这种结构表明，在菌毛挤压过程中，中央门被移位到内壁，不需要额外的构象变化，因为内径可以容纳菌毛。N1结构域被解析，而N0和N-末端结合肽聚糖的β结构域在班级平均图像和最终的3D图中缺失，表明其具有很高的灵活性。这些数据提供了迄今为止T4aP分泌素的最高分辨率结构。
Type IVa pili (T4aP) function as bacterial virulence factors. T4aP pass through the outer membranes of Gram-negative bacteria via homo-oligomeric secretins. We present a 7.4 angstrom cryoelectron microscopy structure of the Pseudomonas aeruginosa PilQ secretin. Peripheral and internal features show that the secretin is composed of 14 subunits with C7 symmetry. The channel is a ribbed cylinder with central peripheral spokes and a central gate closed on the periplasmic side. The structure suggests that during pilus extrusion, the central gate is displaced to the interior walls and that no additional conformational changes are required, as the internal diameter can accommodate the pilus. The N1 domain was resolved, while the N0 and the N-terminal beta-domains proposed to bind peptidoglycan were absent in class average images and the final 3D map, indicating a high flexibility. These data provide the highest-resolution structure to date of a T4aP secretin.