ESCHERICHIA-COLI TRANSCRIPT CLEAVAGE FACTORS GREA AND GREB STIMULATE PROMOTER ESCAPE AND GENE-EXPRESSION IN-VIVO AND IN-VITRO
ESCHERICHIA-COLI TRANSCRIPT CLEAVAGE FACTORS GREA AND GREB STIMULATE PROMOTER ESCAPE AND GENE-EXPRESSION IN-VIVO AND IN-VITRO
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DOI：
10.1073/pnas.92.25.11588
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发表时间：
1995-12-05
影响因子：
11.1
通讯作者：
CHAMBERLIN, MJ
中科院分区：
文献类型：
--
作者：
HSU, LM;VO, NV;CHAMBERLIN, MJ
RNA聚合酶引发RNA链的过程在转录调控中起着核心作用，在这个复杂的转录阶段，短的寡聚体被合成并从酶-启动子复合体中释放出来，这一反应被称为流产起始。该聚合酶在完成启动过程之前经历了许多次失败的启动过程，这是通过酶移位离开启动子、释放一个因子和形成一个稳定结合RNA的伸长复合体来表示的。我们研究了影响大肠杆菌RNA聚合酶对噬菌体T7 A1启动子、噬菌体T5 N25启动子和嵌合启动子T5 N25(AntiDSR)逃逸的参数。后者含有一个合成的初始转录区域，降低了其在体内和体外合成RNA的能力。加入大肠杆菌转录切割因子greA或Greb，可以在体外刺激从T5N25(AntiDSR)清除高达10倍，但这些因素对正常T7A1或T5N25启动子的转录几乎没有影响。使用缺乏GREA和GREB的大肠杆菌菌株，我们也能够在体内显示来自T5N25(AntiDSR)启动子的GRE因子对转录的刺激。转录延伸反应中GRE因子对RNA链启动的刺激作用及其已知的生化特性，为转录启动反应中的步骤提出了一些特定的模型。
The process of RNA chain initiation by RNA polymerases plays a central role in the regulation of transcription, In this complex phase of transcription, short oligomers are synthesized and released from the enzyme-promoter complex in a reaction termed abortive initiation. The polymerase undergoes many cycles of abortive initiation prior to completion of the initiation process, which is signaled by the translocation of the enzyme away from the promoter, release of a factor, and formation of an elongation complex in which the RNA is stably bound, We have studied the parameters that affect escape from the promoter by Escherichia coli RNA polymerase for the phage T7 A1 promoter, the phage T5 N25 promoter, and the chimeric promoter T5 N25(antiDSR). The latter site contains a synthetic initial transcribed region that reduces its ability to synthesize RNA both in vivo and in vitro, Clearance from T5 N25(antiDSR) can be stimulated up to 10-fold in vitro by addition of the E. coli transcript cleavage factor GreA or GreB, but these factors have little effect on transcription from the normal T7 A1 or T5 N25 promoters. Using an E. coli strain lacking GreA and GreB, we were also able to show stimulation of transcription by the Gre factors from the T5 N25(antiDSR) promoter in vivo. The stimulation of RNA chain initiation by Gre factors, together with their known biochemical properties in the transcription elongation reaction, suggests some specific models for steps in the transcription initiation reaction.