PURIFIED LEXA PROTEIN IS A REPRESSOR OF THE RECA AND LEXA GENES
PURIFIED LEXA PROTEIN IS A REPRESSOR OF THE RECA AND LEXA GENES
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DOI：
10.1073/pnas.78.7.4199
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发表时间：
1981-01-01
期刊：
影响因子：
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通讯作者：
YANISCHPERRON, CR
中科院分区：
文献类型：
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作者：
LITTLE, JW;MOUNT, DW;YANISCHPERRON, CR
大肠杆菌对损伤DNA或抑制DNA复制的处理表现出多效性反应（SOS反应）。显然，莱克萨基因的产物可能作为阻遏物参与调节SOS反应，并且它对recA蛋白酶敏感。所述莱克萨蛋白是至少2种基因recA和莱克萨的阻遏物。纯化的蛋白质结合特异性的2个基因的调控区，判断由DNase I保护实验，它特异性地抑制这两个基因的体外转录。recA和莱克萨的结合位点分别约为20 bp和40 bp。莱克萨中的40 bp序列由2个相邻的20 bp序列组成，这2个序列彼此之间以及与相应的recA序列之间具有相当大的同源性。这些20 bp的序列，称为SOS盒，也显示出相当大的反向重复结构。这些特征表明，每个盒子代表一个单一的阻遏物结合位点。纯化的莱克萨蛋白质是recA蛋白酶在需要ATP或类似物腺苷5“-[γ-ATP]的反应中的底物。硫代]三磷酸和变性DNA。
Escherichia coli shows a pleiotropic response (the SOS response) to treatments that damage DNA or inhibit DNA replication. Apparently, the product of the lexA gene is involved in regulating the SOS response, perhaps as a repressor, and it is sensitive to the recA protease. The lexA protein is a repressor of at least 2 genes, recA and lexA. Purified protein bound specifically to the regulatory regions of the 2 genes, as judged by DNase I protection experiments, and it specifically inhibited in vitro transcription of both genes. The binding sites in recA and lexA were about 20 base pairs (bp) and 40 bp long, respectively. The 40-bp sequence in lexA was composed of 2 adjacent 20-bp sequences, which had considerable homology to one another and to the corresponding recA sequence. These 20-bp sequences, termed SOS boxes, show considerable inverted repeat structure as well. These features suggest that each box represents a single repressor binding site. Purified lexA protein was a substrate for the recA protease in a reaction requiring ATP or an analog, adenosine 5''-[.gamma.-thio]triphosphate and denatured DNA.