Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
Department of Biochemistry, The University of Texas Health Science Center, San Antonio, TX 78229, USA.
Structure. 2018 Feb 6;26(2):238-248.e3. doi: 10.1016/j.str.2017.12.001. Epub 2017 Dec 28.
Marine bacteriophage TW1 belongs to the Siphoviridae family and infects Pseudoalteromonas phenolica. Mass spectrometry analysis has identified 16 different proteins in the TW1 virion. Functions of most of these proteins have been predicted by bioinformatic methods. A 3.6 Å resolution cryoelectron microscopy map of the icosahedrally averaged TW1 head showed the atomic structures of the major capsid protein, gp57, and the capsid-stabilizing protein, gp56. The gp57 structure is similar to that of the phage HK97 capsid protein. The gp56 protein has two domains, each having folds similar to that of the N-terminal part of phage λ gpD, indicating a common ancestry. The first gp56 domain clamps adjacent capsomers together, whereas the second domain is required for trimerization. A 6-fold-averaged reconstruction of the distal part of the tail showed that TW1 has six tail spikes, which are unusual for siphophages but are similar to the podophages P22 and Sf6, suggesting a common evolutionary origin of these spikes.
海洋噬菌体 TW1 属于长尾噬菌体科，感染假交替单胞菌。质谱分析鉴定了 TW1 病毒粒子中的 16 种不同的蛋白质。通过生物信息学方法预测了这些蛋白质的大多数功能。TW1 头部的 3.6Å 分辨率冷冻电镜图谱显示了主要衣壳蛋白 gp57 和衣壳稳定蛋白 gp56 的原子结构。gp57 结构与噬菌体 HK97 衣壳蛋白相似。gp56 蛋白有两个结构域，每个结构域的折叠都类似于噬菌体 λ gpD 的 N 端部分，表明它们具有共同的祖先。第一个 gp56 结构域将相邻的衣壳蛋白夹在一起，而第二个结构域则是三聚化所必需的。尾部远端的 6 重平均重建显示，TW1 有六个尾刺，这对于长尾噬菌体来说是不寻常的，但与 podophages P22 和 Sf6 相似，表明这些刺具有共同的进化起源。
