Bishop L J, Bjes E S, Davidson V L, Cramer W A
J Bacteriol. 1985 Oct;164(1):237-44. doi: 10.1128/jb.164.1.237-244.1985.
The region of the colicin E1 polypeptide that interacts with immunity protein has been localized to a 168-residue COOH-terminal peptide. This is the length of a proteolytically generated peptide fragment of colicin E1 against which imm+ function can be demonstrated in osmotically shocked cells. The role of particular amino acids of the COOH-terminal peptide in the expression of the immune phenotype was studied. Chemical modification showed that the two histidine residues (His 427 and His 440) and the single cysteine residue (Cys 505) present in the COOH-terminal peptide were not necessary for the colicin-immunity protein interaction. The immunity protein was localized in the cytoplasmic membrane fraction, consistent with previous work of others on the colicin Ia immunity protein and the prediction from the immunity protein amino acid sequence that it is a hydrophobic protein. The distribution of hydrophobic residues along the immunity polypeptide was calculated.
与免疫蛋白相互作用的大肠杆菌素E1多肽区域已定位到一个含168个残基的羧基末端肽段。这是大肠杆菌素E1经蛋白水解产生的肽片段的长度，在经渗透压休克处理的细胞中可证明该片段具有免疫阳性功能。研究了羧基末端肽段中特定氨基酸在免疫表型表达中的作用。化学修饰表明，羧基末端肽段中存在的两个组氨酸残基（His 427和His 440）和单个半胱氨酸残基（Cys 505）对于大肠杆菌素-免疫蛋白相互作用并非必需。免疫蛋白定位于细胞质膜部分，这与其他人先前关于大肠杆菌素Ia免疫蛋白的研究工作以及根据免疫蛋白氨基酸序列预测其为疏水蛋白的结果一致。计算了免疫多肽上疏水残基的分布。
