Genetic identification of the DNA binding domain of Escherichia coli LexA protein.-猫眼课题宝

大肠杆菌 LexA 蛋白 DNA 结合域的遗传鉴定。

DOI：

10.1073/pnas.89.10.4500

发表时间：

1992

期刊：

Proceedings of the National Academy of Sciences of the United States of America

影响因子：

11.1

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

Thliveris,AT;Mount,DW

采用两种遗传学方法来确定大肠杆菌SOS调节子的阻遏物莱克萨蛋白的DNA结合结构域。首先，分离出几个DNA结合缺陷的显性负性莱克萨突变体。这些突变改变了与螺旋-转角-螺旋相似区域的氨基酸，螺旋-转角-螺旋是其他阻遏物和DNA结合蛋白的DNA结合结构域。第二，对编码预测的DNA识别螺旋的区域进行寡核苷酸定向诱变，并分离出对几个recA操纵基因位置具有改变的或松弛的特异性的突变体莱克萨蛋白。通过研究一系列氨基酸取代对阻遏物特异性的影响，表明莱克萨蛋白中45位的谷氨酸残基对于recA操纵子中第一个碱基对（G. C）的识别是重要的。

Two genetic approaches were taken to define the DNA binding domain of LexA protein, the repressor of the Escherichia coli SOS regulon. First, several dominant negative lexA mutants defective in DNA binding were isolated. The mutations altered amino acids in a region similar to the helix-turn-helix, a DNA binding domain of other repressors and DNA binding proteins. Second, the region encoding the predicted DNA recognition helix was subjected to oligonucleotide-directed mutagenesis and mutant LexA proteins with altered or relaxed specificity for several recA operator positions were isolated. By examining the effects of a series of amino acid substitutions on repressor specificity, it was shown that a glutamic acid residue at position 45 in LexA protein is important for recognition of the first base pair (G.C) in the recA operator.