Arisaka Fumio, Kanamaru Shuji, Leiman Petr, Rossmann Michael G
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, 226-8510, Yokohama, Japan.
Int J Biochem Cell Biol. 2003 Jan;35(1):16-21. doi: 10.1016/s1357-2725(02)00098-5.
The tail baseplate of bacteriophage T4 contains a structurally essential, three-domain protein encoded by gene 5 in which the middle domain possesses lysozyme activity. The gene 5 product (gp5) undergoes post-translational cleavage, allowing the resultant N-terminal domain (gp5*) to assemble into the baseplate as a trimer. The lysozyme activity of the undissociated cleaved gp5 is inhibited until infection has been initiated, when the C-terminal portion of the molecule is detached and the rest of the molecule dissociates into monomers. The 3D structure of the undissociated cleaved gp5, complexed with gp27 (another component of the baseplate), shows that it is a cell-puncturing device that functions to penetrate the outer cell membrane and to locally dissolve the periplasmic cell wall.
噬菌体T4的尾基板包含一种由基因5编码的结构必需的三结构域蛋白，其中间结构域具有溶菌酶活性。基因5产物（gp5）经历翻译后切割，使产生的N端结构域（gp5*）以三聚体形式组装到基板中。未解离的切割后gp5的溶菌酶活性受到抑制，直到感染开始，此时分子的C端部分分离，分子的其余部分解离成单体。未解离的切割后gp5与gp27（基板的另一个组分）形成的复合物的三维结构表明，它是一种细胞穿刺装置，其功能是穿透细胞外膜并局部溶解周质细胞壁。
