噬菌体尾纤维(或称为尾尖峰)通过与细菌表面结合在感染的早期阶段中起关键作用。具有已知结构的噬菌体通常具有一种或两种类型的纤维。这里,我们通过cryo-EM将podophageGP4的不对称结构解析为近原子分辨率。我们的结构揭示了GP4尾部组件与以前从未见过的拓扑之间的对称失配关系。详细来说,两个十二聚体适配器(适配器I和II),六聚体喷嘴,和尾针形成保守的尾体,该尾体连接到占据二十面体头部的独特顶点的十二聚体入口。然而,五个链状延伸纤维(纤维I)和五个郁金香状短纤维(纤维II)锚定在15倍对称的纤维尾适配器上,环绕适配器I,和六个竹状三聚纤维(纤维III)连接到喷嘴。五根纤维I,每个都由五个蛋白质gp80的二聚体组成,由细长的绳索蛋白质连接,连接到二十面体头部的尾部顶点的五个边缘。在这项研究中,我们发现了一种新的podophage结构,有三种类型的尾纤维,并且这种具有不同类型纤维的噬菌体可能具有广泛的宿主范围和/或以相当高的效率感染宿主细胞,在恶劣环境中提供进化优势。
Bacteriophage tail fibers (or called tail spikes) play a critical role in the early stage of infection by binding to the bacterial surface. Podophages with known structures usually possess one or two types of fibers. Here, we resolved an asymmetric structure of the podophage GP4 to near-atomic resolution by cryo-EM. Our structure revealed a symmetry-mismatch relationship between the components of the GP4 tail with previously unseen topologies. In detail, two dodecameric adaptors (adaptors I and II), a hexameric nozzle, and a tail needle form a conserved tail body connected to a dodecameric portal occupying a unique vertex of the icosahedral head. However, five chain-like extended fibers (fiber I) and five tulip-like short fibers (fiber II) are anchored to a 15-fold symmetric fiber-tail adaptor, encircling the adaptor I, and six bamboo-like trimeric fibers (fiber III) are connected to the nozzle. Five fibers I, each composed of five dimers of the protein gp80 linked by an elongated rope protein, are attached to the five edges of the tail vertex of the icosahedral head. In this study, we identified a new structure of the podophage with three types of tail fibers, and such phages with different types of fibers may have a broad host range and/or infect host cells with considerably high efficiency, providing evolutionary advantages in harsh environments.