Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
National Cryo-EM Facility, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA.
Viruses. 2023 Jul 31;15(8):1673. doi: 10.3390/v15081673.
Antibiotic resistance poses a growing risk to public health, requiring new tools to combat pathogenic bacteria. Contractile injection systems, including bacteriophage tails, pyocins, and bacterial type VI secretion systems, can efficiently penetrate cell envelopes and become potential antibacterial agents. Bacteriophage XM1 is a dsDNA virus belonging to the family and infecting Vibrio bacteria. The XM1 virion, made of 18 different proteins, consists of an icosahedral head and a contractile tail, terminated with a baseplate. Here, we report cryo-EM reconstructions of all components of the XM1 virion and describe the atomic structures of 14 XM1 proteins. The XM1 baseplate is composed of a central hub surrounded by six wedge modules to which twelve spikes are attached. The XM1 tail contains a fewer number of smaller proteins compared to other reported phage baseplates, depicting the minimum requirements for building an effective cell-envelope-penetrating machine. We describe the tail sheath structure in the pre-infection and post-infection states and its conformational changes during infection. In addition, we report, for the first time, the in situ structure of the phage neck region to near-atomic resolution. Based on these structures, we propose mechanisms of virus assembly and infection.
抗生素耐药性对公共健康构成了日益严重的威胁，需要新的工具来对抗致病细菌。收缩性注射系统，包括噬菌体尾部、噬菌体素和细菌类型 VI 分泌系统，可以有效地穿透细胞膜，并成为潜在的抗菌剂。噬菌体 XM1 是一种 dsDNA 病毒，属于 科，感染弧菌。XM1 病毒粒子由 18 种不同的蛋白质组成，由一个二十面体头部和一个可收缩的尾部组成，尾部末端有一个基板。在这里，我们报告了 XM1 病毒粒子所有成分的 cryo-EM 重建，并描述了 14 种 XM1 蛋白的原子结构。XM1 基板由一个中央轮毂组成，轮毂周围有六个楔形模块，模块上附着有十二个刺突。与其他报道的噬菌体基板相比，XM1 尾部含有较少数量的较小蛋白质，描绘了构建有效穿透细胞膜的机器的最小要求。我们描述了感染前和感染后的尾部鞘结构及其在感染过程中的构象变化。此外，我们首次报告了噬菌体颈部区域的原位结构，分辨率接近原子水平。基于这些结构，我们提出了病毒组装和感染的机制。
