Institute of Interdisciplinary Studies, Key Laboratory for Matter Microstructure and Function of Hunan Province, Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control, Hunan Normal University, Changsha 410082, China.
State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, China.
Viruses. 2023 May 29;15(6):1267. doi: 10.3390/v15061267.
The phage tail is a common component of contractile injection systems (CISs), essential for exerting contractile function and facilitating membrane penetration of the inner tail tube. The near-atomic resolution structures of the tail have been extensively studied, but the dynamic conformational changes before and after contraction and the associated molecular mechanism are still unclear. Here, we present the extended and contracted intact tail-structures of phage P1 by cryo-EM. The ultra-long tail of P1, 2450 Å in length, consists of a neck, a tail terminator, 53 repeated tail sheath rings, 53 repeated tube rings, and a baseplate. The sheath of the contracted tail shrinks by approximately 55%, resulting in the separation of the inner rigid tail tube from the sheath. The extended and contracted tails were further resolved by local reconstruction at 3.3 Å and 3.9 Å resolutions, respectively, allowing us to build the atomic models of the tail terminator protein gp24, the tube protein BplB, and the sheath protein gp22 for the extended tail, and of the sheath protein gp22 for the contracted tail. Our atomic models reveal the complex interaction network in the ultra-long tail and the novel conformational changes of the tail sheath between extended and contracted states. Our structures provide insights into the contraction and stabilization mechanisms of the tail.
噬菌体尾部是收缩型注射系统（CISs）的常见组成部分，对于发挥收缩功能和促进内部尾管穿透细胞膜至关重要。尾部的近原子分辨率结构已得到广泛研究，但收缩前后的动态构象变化及其相关的分子机制仍不清楚。在这里，我们通过 cryo-EM 呈现了噬菌体 P1 的完整延伸和收缩尾部结构。P1 的超长尾部长 2450Å，由颈部、尾部终止子、53 个重复的尾部鞘环、53 个重复的管环和基板组成。收缩后的尾部鞘收缩约 55%，导致内部刚性尾管与鞘分离。进一步通过局部重建分别以 3.3Å 和 3.9Å 的分辨率解析了延伸和收缩的尾部，使我们能够构建延伸尾部的尾部终止子蛋白 gp24、管蛋白 BplB 和鞘蛋白 gp22 的原子模型，以及收缩尾部的鞘蛋白 gp22 的原子模型。我们的原子模型揭示了超长尾部中复杂的相互作用网络以及鞘在延伸和收缩状态之间的新颖构象变化。我们的结构为尾部的收缩和稳定机制提供了深入了解。
