THE DNA LOOP MODEL FOR ARA REPRESSION - ARAC PROTEIN OCCUPIES THE PROPOSED LOOP SITES INVIVO AND REPRESSION-NEGATIVE MUTATIONS LIE IN THESE SAME SITES
THE DNA LOOP MODEL FOR ARA REPRESSION - ARAC PROTEIN OCCUPIES THE PROPOSED LOOP SITES INVIVO AND REPRESSION-NEGATIVE MUTATIONS LIE IN THESE SAME SITES
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DOI：
10.1073/pnas.83.11.3654
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发表时间：
1986-06-01
影响因子：
11.1
通讯作者：
SCHLEIF, RF
中科院分区：
文献类型：
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作者：
MARTIN, K;HUO, L;SCHLEIF, RF
已经进行了两组实验来测试抑制大肠杆菌 araBAD 操纵子的 DNA 环模型。首先，对正常生长的细胞进行的硫酸二甲酯甲基化保护测量表明，无论诱导物阿拉伯糖存在还是不存在，AraC 调节蛋白都会占据 araI 位点。类似地，无论存在或不存在阿拉伯糖，araO2 位点都会被 AraC 蛋白占据；然而，当 araI 和相邻序列被删除时，AraC 的占用量大大减少。因此，AraC 蛋白与 araO2 结合，并与 ara 系统中至少 60 个碱基对相距的其他成分协同结合。其次，这里提出的突变分析表明，抑制 araBAD 和 araI、araO2 以及可能还有 araBAD 操纵子 RNA 聚合酶结合位点所需的 DNA 成分。
Two sets of experiments have been performed to test the DNA loop model of repression of the araBAD operon of Escherichia coli. First, dimethyl sulfate methylation protection measurements on normally growing cells show that the AraC regulatory proteins occupies the araI site in the presence and absence of the inducer arabinose. Similarly, the araO2 site is shown to be occupied by AraC protein in the presence and absence of arabinose; however, its occupancy by AraC is greatly reduced when araI and adjacent sequences are deleted. Thus, AraC protein binds to araO2 cooperatively with some other component of the ara system located at least 60 base pairs away. Second, the mutational analysis presented here shows that the DNA components required for repression of araBAD and araI, araO2, and perhaps the araBAD operon RNA polymerase binding site.