Mende J, Braun V
Mikrobiologie II, Universität Tübingen, FRG.
Mol Microbiol. 1990 Sep;4(9):1523-33. doi: 10.1111/j.1365-2958.1990.tb02063.x.
The pore-forming colicin B is taken up into Escherichia coli by a receptor and TonB-dependent process. The receptor and colicin B both contain a similar amino acid sequence, close to the N-terminal end, termed the TonB box. Point mutations were introduced into the TonB-box region of the colicin B structural gene cba resulting in colicin B derivatives which were partially or totally inactive against E. coli cells. All derivatives still bound to the receptor. An inactive derivative killed cells when translocated across the outer membrane by osmotic shock treatment, and formed pores in planar lipid bilayer membranes identical to the wild-type colicin. Some of the mutations were partially suppressed by mutations in the tonB structural gene. It was concluded that the TonB-box mutations define a region that is involved in the uptake of colicin B across the outer membrane.
成孔性大肠杆菌素B通过一种受体及依赖TonB的过程被摄取到大肠杆菌中。受体和大肠杆菌素B在靠近N末端处都含有一段相似的氨基酸序列，称为TonB框。将点突变引入大肠杆菌素B结构基因cba的TonB框区域，产生了对大肠杆菌细胞部分或完全无活性的大肠杆菌素B衍生物。所有衍生物仍能与受体结合。一种无活性的衍生物在通过渗透压休克处理跨外膜转运时可杀死细胞，并在平面脂质双分子层膜中形成与野生型大肠杆菌素相同的孔。tonB结构基因中的突变部分抑制了一些突变。得出的结论是，TonB框突变定义了一个参与大肠杆菌素B跨外膜摄取的区域。
