Differential binding of Lrp to two sets of pap DNA binding sites mediated by Pap I regulates Pap phase variation in Escherichia coli.
Differential binding of Lrp to two sets of pap DNA binding sites mediated by Pap I regulates Pap phase variation in Escherichia coli.
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Lrp 与 Pap I 介导的两组 pap DNA 结合位点的差异结合可调节大肠杆菌中的 Pap 相位变化。
DOI：
10.1002/j.1460-2075.1995.tb00267.x
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Low,DA
中科院分区：
文献类型：
--
作者：
Nou,X;Braaten,B;Kaltenbach,L;Low,DA
肾盂肾炎相关菌毛(Pap)在大肠杆菌中的表达受亮氨酸反应调节蛋白(LRP)、PAPI和脱氧腺苷甲基酶(DAM)调控的时相变化控制机制的控制。在以前的工作中，我们发现PAP调控DNA中两个靶点GATC-I和GATC II的差异Dam甲基化对于PAP转录状态的活跃和非活跃之间的转换是必不可少的。在这里，我们确定了PAP调控DNA中的六个LRP结合位点，每个结合位点都被大约三个螺旋转角隔开。LRP与PapBAp启动子近端的三个位点(1、2和3)具有最高的亲和力。突变分析表明，Lrp与2和3位点的结合抑制了PAP的转录，这与Lrp结合位点3位于PapBAp的−35和−10RNA聚合酶结合区之间的事实一致。PAPI的加入降低了LRP对1、2和3位点的亲和力，而增加了其对远端LRP结合位点4和5的亲和力。LRP结合位点4和5内的突变关闭了PAP转录，表明LRP与该PAP区域的结合激活了PAP转录。PAP GATC-I和GATC-II甲基化位点分别位于LRP结合位点5和2，提供了一种DAM控制LRP结合和Pap阶段变化的机制。
Pyelonephritis‐associated pili (Pap) expression in Escherichia coli is subject to a phase variation control mechanism that is regulated by the leucine‐responsive regulatory protein (Lrp), PapI, and deoxyadenosine methylase (Dam). In previous work, we found that the differential Dam methylation of two target sites in pap regulatory DNA, GATC‐I and GATC II, is essential for the transition between active and inactive pap transcriptional states. Here, we identify six Lrp binding sites within the pap regulatory DNA, each separated by about three helical turns. Lrp binds with highest affinity to three sites (1, 2 and 3) proximal to the papBAp promoter. A mutational analysis indicates that the binding of Lrp to sites 2 and 3 inhibits pap transcription, which is consistent with the fact that Lrp binding site 3 is located between the −35 and −10 RNA polymerase binding region of papBAp. The addition of PapI decreases the affinity of Lrp for sites 1, 2 and 3 and increases its affinity for the distal Lrp binding sites 4 and 5. Mutations within Lrp binding sites 4 and 5 shut off pap transcription, indicating that the binding of Lrp to this pap region activates pap transcription. The pap GATC‐I and GATC‐II methylation sites are located within Lrp binding sites 5 and 2, respectively, providing a mechanism by which Dam controls Lrp binding and Pap phase variation.