Cryo-EM Structure and Assembly of an Extracellular Contractile Injection System
Cryo-EM Structure and Assembly of an Extracellular Contractile Injection System
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细胞外收缩注射系统的冷冻电镜结构和组装
DOI：
10.1016/j.cell.2019.02.020
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发表时间：
2019-04-04
期刊：
影响因子：
64.5
通讯作者：
Gao, Ning
中科院分区：
文献类型：
--
作者：
Jiang, Feng;Li, Ningning;Gao, Ning
收缩注射系统（CIS）是与收缩尾噬菌体共享祖先的细胞穿刺纳米装置。光杆状菌毒力盒（PVC）代表了一组存在于细菌和古细菌中的细胞外CIS。在这里，我们报告了来自P. asybiotica的完整PVC的冷冻电镜结构。这个超过10 MDa的装置类似于简化的T4噬菌体尾部，包含一个具有六根纤维的六边形基板复合物和一个带帽的117纳米鞘管主干。PVC的一个显著特征是管和鞘蛋白都存在三种变体，这表明它们在进化过程中具有功能特化。末端六聚体帽对接到内管的最顶层上，并且用六个拉伸臂将外鞘锁定在预收缩状态。我们对PVC的研究结果为理解广泛分布的CIS的一般机制提供了一个框架，并为将其用作生物或治疗应用中的递送工具提供了途径。
Contractile injection systems (CISs) are cell-puncturing nanodevices that share ancestry with contractile tail bacteriophages. Photorhabdus virulence cassette (PVC) represents one group of extracellular CISs that are present in both bacteria and archaea. Here, we report the cryo-EM structure of an intact PVC from P. asymbiotica. This over 10-MDa device resembles a simplified T4 phage tail, containing a hexagonal baseplate complex with six fibers and a capped 117-nanometer sheath-tube trunk. One distinct feature of the PVC is the presence of three variants for both tube and sheath proteins, indicating a functional specialization of them during evolution. The terminal hexameric cap docks onto the topmost layer of the inner tube and locks the outer sheath in pre-contraction state with six stretching arms. Our results on the PVC provide a framework for understanding the general mechanism of widespread CISs and pay the way for using them as delivery tools in biological or therapeutic applications.