Transcription activation at class II CRP-dependent promoters: The role of different activating regions
Transcription activation at class II CRP-dependent promoters: The role of different activating regions
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DOI：
10.1093/nar/25.2.326
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发表时间：
1997-01-15
影响因子：
14.9
通讯作者：
Savery, NJ
中科院分区：
文献类型：
--
作者：
Rhodius, VA;West, DM;Savery, NJ
大肠杆菌环AMP受体蛋白(CRP)在第二类启动子上的转录激活依赖于两个暴露在表面的活化区(AR1和AR2)和RNA聚合酶中两个接触部位之间的直接相互作用。在不同的II类启动子上已经测量了干扰AR1或AR2对转录激活的影响，在所有被测试的II类启动子中，AR2而不是AR1是激活所必需的，在AR1和AR2中的单个正对照替换的影响因启动子的不同而不同：不同的替换的影响取决于-35六聚体序列，失败的起始试验已经被用来定量每个激活区域的正对照替换对依赖于第二类CRP的启动子pMelRcon转录启动动力学的影响。在该启动子上，AR1中的HL159替换导致RNA聚合酶的初始结合缺陷，而AR2中的KE101替换降低了从封闭复合体到开放复合体的异构化速度。
Transcription activation by the Escherichia coli cyclic AMP receptor protein (CRP) at Class II promoters is dependent on direct interactions between two surface-exposed activating regions (AR1 and AR2) and two contact sites in RNA polymerase. The effects on transcription activation of disrupting either AR1 or AR2 have been measured at different Class II promoters, AR2 but not AR1 is essential for activation at all the Class II promoters that were tested, The effects of single positive control substitutions in AR1 and AR2 vary from one promoter to another: the effects of the different substitutions are contingent on the -35 hexamer sequence, Abortive initiation assays have been used to quantify the effects of positive control substitutions in each activating region on the kinetics of transcription initiation at the Class II CRP-dependent promoter pmelRcon. At this promoter, the HL159 substitution in AR1 results in a defect in the initial binding of RNA polymerase whilst the KE101 substitution in AR2 reduces the rate of isomerization from the closed to the open complex.