Structure of the central hub of bacteriophage Mu baseplate determined by X-ray crystallography of gp44.
Structure of the central hub of bacteriophage Mu baseplate determined by X-ray crystallography of gp44.
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DOI：
10.1016/j.jmb.2005.07.044
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发表时间：
2005-09
影响因子：
5.6
通讯作者：
Y. Kondou;D. Kitazawa;S. Takeda;Y. Tsuchiya;E. Yamashita;M. Mizuguchi;K. Kawano;T. Tsukihara
中科院分区：
文献类型：
--
作者：
Y. Kondou;D. Kitazawa;S. Takeda;Y. Tsuchiya;E. Yamashita;M. Mizuguchi;K. Kawano;T. Tsukihara
Mu噬菌体是一种双链DNA噬菌体，由一个二十面体的头部、一个带有基板的收缩尾巴和六个尾部纤维组成，类似于研究得很好的T-偶数噬菌体。噬菌体Mu的基板在感染过程中识别并附着在宿主细胞上，由至少八种不同的蛋白质组成。基板蛋白gp44对于噬菌体Mu的组装和活性噬菌体的产生是必不可少的。为了研究gp44在基板组装和感染中的作用，采用多重同象置换方法测定了gp44在2.1Å分辨率下的晶体结构。Gp44三聚体的总体结构类似于T4噬菌体gp27三聚体的结构，后者形成了T4基板的中心枢纽，尽管这些蛋白质的初级序列同源性很低。基于这些数据，我们证实gp44以三聚体的形式存在，呈现出内径为25Å的枢纽状结构，推测dna在感染过程中可以通过该结构。与宿主细胞膜相邻的gp44三聚体分子表面带正电荷，很可能是Mu噬菌体通过gp44介导的静电相互作用与细胞膜相互作用。
Bacteriophage Mu is a double-stranded DNA phage that consists of an icosahedral head, a contractile tail with baseplate and six tail fibers, similar to the well-studied T-even phages. The baseplate of bacteriophage Mu, which recognizes and attaches to a host cell during infection, consists of at least eight different proteins. The baseplate protein, gp44, is essential for bacteriophage Mu assembly and the generation of viable phages. To investigate the role of gp44 in baseplate assembly and infection, the crystal structure of gp44 was determined at 2.1Å resolution by the multiple isomorphous replacement method. The overall structure of the gp44 trimer is similar to that of the T4 phage gp27 trimer, which forms the central hub of the T4 baseplate, although these proteins share very little primary sequence homology. Based on these data, we confirm that gp44 exists as a trimer exhibiting a hub-like structure with an inner diameter of 25Å through which DNA can presumably pass during infection. The molecular surface of the gp44 trimer that abuts the host cell membrane is positively charged, and it is likely that Mu phage interacts with the membrane through electrostatic interactions mediated by gp44.