MECHANISM OF CRP-CAMP ACTIVATION OF LAC OPERON TRANSCRIPTION INITIATION ACTIVATION OF THE P1 PROMOTER
MECHANISM OF CRP-CAMP ACTIVATION OF LAC OPERON TRANSCRIPTION INITIATION ACTIVATION OF THE P1 PROMOTER
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DOI：
10.1016/0022-2836(84)90262-6
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发表时间：
1984-01-01
影响因子：
5.6
通讯作者：
MCCLURE, WR
中科院分区：
文献类型：
--
作者：
MALAN, TP;KOLB, A;MCCLURE, WR
CRP-cAMP显示在体外激活大肠杆菌lac启动子处的转录起始，这是2种单独作用的结果。一个间接的组件的激活导致从一个增强的部分启动子有效结合RNA聚合酶。这种效应主要是由于CRP-cAMP抑制RNA聚合酶结合到启动子区域内的重叠位点（lac P2）。直接增强的RNA聚合酶结合在主要的乳糖启动子（lac P1）被发现。CRP-cAMP的间接和直接激活的组合被认为是负责在体内观察到的大激活。还确定了L 8、UV 5和Ps启动子的启动子强度参数。CRP-cAMP对这些突变型启动子的影响与乳糖野生型启动子的激活机制一致。DNA超螺旋增强了紫胶野生型和UV 5启动子的启动子强度。超螺旋和CRP-cAMP的组合对于乳糖野生型启动子的最佳启动子强度是必要的。
CRP-cAMP was shown to activate transcription initiation at the Escherichia coli lac promoter in vitro as a result of 2 separate effects. An indirect component of the activation resulted from an enhancement of the fraction of promoters productively bound by RNA polymerase. This effect was due largely to CRP-cAMP repression of RNA polymerase binding to an overlapping site (lac P2) within the promoter region. A direct enhancement of RNA polymerase binding at the principal lac promoter (lac P1) was found. The combination of indirect and direct activation by CRP-cAMP was suggested to be responsible for the large activation observed in vivo. Promoter strength parameters were also determined for the L8, UV5 and Ps promoters. The effect of CRP-cAMP on these mutant promoters was shown to be consistent with the activation mechanism deduced for the lac wild-type promoter. DNA supercoiling enhanced the promoter strength of the lac wild-type and UV5 promoters. The combination of supercoiling and CRP-cAMP was necessary for optimal promoter strength for the lac wild-type promoter.