Suga H, Shirabe K, Yamamoto T, Tasumi M, Umeda M, Nishimura C, Nakazawa A, Nakanishi M, Arata Y
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
J Biol Chem. 1991 Jul 25;266(21):13537-43.
Structural changes upon binding to the membrane of a COOH-terminal channel-forming thermolytic fragment of colicin E1 have been studied by means of a variety of spectroscopic techniques. Circular dichroism measurements show that the thermolytic fragment predominantly takes a helical structure in aqueous and detergent solutions. Fourier transform infrared spectroscopic measurements indicate that the content of the beta-structure is significantly increased when the thermolytic fragment is bound to vesicles. On the basis of the result of tryptophan fluorescence measurements, we have concluded that each of the three tryptophan residues of the thermolytic fragment exists in different environments, i.e. one is buried in the lipid bilayer, one exists on the cis side of the vesicles, and one exists near the surface of the lipid bilayer. The Fourier transform infrared and fluorescence data have been used along with the crystal structure of colicin A, which is highly homologous to colicin E1 in structure and function, to propose a model of the thermolytic fragment bound to the lipid vesicles.
通过多种光谱技术研究了大肠杆菌素E1的COOH末端通道形成热解片段与膜结合时的结构变化。圆二色性测量表明，热解片段在水性和去污剂溶液中主要呈螺旋结构。傅里叶变换红外光谱测量表明，当热解片段与囊泡结合时，β-结构的含量显著增加。基于色氨酸荧光测量结果，我们得出结论，热解片段的三个色氨酸残基各自存在于不同的环境中，即一个埋藏在脂质双层中，一个存在于囊泡的顺式侧，一个存在于脂质双层表面附近。傅里叶变换红外光谱和荧光数据与大肠杆菌素A的晶体结构一起使用，大肠杆菌素A在结构和功能上与大肠杆菌素E1高度同源，以提出热解片段与脂质囊泡结合的模型。
