Cramer W A, Heymann J B, Schendel S L, Deriy B N, Cohen F S, Elkins P A, Stauffacher C V
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
Annu Rev Biophys Biomol Struct. 1995;24:611-41. doi: 10.1146/annurev.bb.24.060195.003143.
The channel-forming colicins are plasmid-encoded bacteriocins that kill E. coli and related cells and whose mode of action is of interest in related problems of protein import and toxicology. Colicins parasitize metabolite receptors in the outer membrane and translocate across the periplasm with the aid of the Tol or Ton protein systems. X-ray structure data for the channel domain and colicin are available. Residues have been identified that affect the channel ion selectivity and particular helices implicated in channel structure and in conformational changes required for binding or insertion of the channel into the membrane. Unique aspects of the colicin channel system are the involvement of protein import in the gating process, the existence of multiple open and closed states, and the existence and action of an immunity protein that involves specific intramembrane helix-helix interactions with transmembrane helices of the colicin channel-forming domains.
形成通道的大肠杆菌素是由质粒编码的细菌素，可杀死大肠杆菌及相关细胞，其作用方式在蛋白质导入和毒理学相关问题中备受关注。大肠杆菌素寄生于外膜中的代谢物受体，并借助Tol或Ton蛋白系统穿过周质。目前已有通道结构域和大肠杆菌素的X射线结构数据。已鉴定出影响通道离子选择性的残基以及与通道结构、通道结合或插入膜所需的构象变化相关的特定螺旋。大肠杆菌素通道系统的独特之处在于蛋白质导入参与门控过程、存在多种开放和关闭状态，以及存在一种免疫蛋白，该免疫蛋白涉及与大肠杆菌素通道形成结构域的跨膜螺旋进行特定的膜内螺旋-螺旋相互作用。
