Manly S P, Bennett G N, Matthews K S
Proc Natl Acad Sci U S A. 1983 Oct;80(20):6219-23. doi: 10.1073/pnas.80.20.6219.
Operator DNA fragments were modified in the presence of lac repressor protein or its trypsin-resistant core. Operator DNA was alkylated or cleaved enzymatically with these related proteins present to compare the influences of their binding on the reactivities or enzymatic susceptibilities of individual bases in the sequence. These two protein species have pronounced and distinguishable effects on the reactivity of the bases of the operator fragment toward methylation by dimethyl sulfate. Perturbation of base alkylation by the trypsin-resistant core repressor is most pronounced in the inner, asymmetric region of the operator DNA, while repressor effects extend further on either end of the operator sequence. Digestion of the two protein-operator complexes by DNase I yields fragment patterns that differ primarily in extent of protection. These data extend the experimental base supporting the involvement of the core region of the lac repressor in addition to its NH2 termini in the operator-specific binding activity of this protein.
操纵基因DNA片段在乳糖阻遏蛋白或其胰蛋白酶抗性核心存在的情况下进行了修饰。使操纵基因DNA在这些相关蛋白存在时发生烷基化或酶切，以比较它们的结合对序列中单个碱基的反应性或酶敏感性的影响。这两种蛋白质对操纵基因片段碱基甲基化反应性具有显著且可区分的影响。胰蛋白酶抗性核心阻遏物对碱基烷基化的干扰在操纵基因DNA的内部不对称区域最为明显，而阻遏物的影响在操纵基因序列的两端延伸得更远。用DNase I消化这两种蛋白质 - 操纵基因复合物产生的片段模式主要在保护程度上有所不同。这些数据扩展了实验依据，支持除了其NH2末端外，乳糖阻遏蛋白的核心区域也参与该蛋白的操纵基因特异性结合活性。
