In vitro studies of transcript initiation by Escherichia coli RNA polymerase.: 3.: Influences of individual DNA elements within the promoter recognition region on abortive initiation and promoter escape
In vitro studies of transcript initiation by Escherichia coli RNA polymerase.: 3.: Influences of individual DNA elements within the promoter recognition region on abortive initiation and promoter escape
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DOI：
10.1021/bi026962v
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发表时间：
2003-04-08
期刊：
影响因子：
2.9
通讯作者：
Chamberlin, MJ
中科院分区：
文献类型：
--
作者：
Vo, NV;Hsu, LM;Chamberlin, MJ
终止起始和启动子逃逸是转录起始后期的两个主要生化反应。我们已经分析了单个DNA元件的启动子识别区（PRR）内对这些反应的影响，通过测量的定量起始参数，描述流产启动和启动子逃逸，这些参数是流产率，生产率，流产：生产率，流产概率，和流产成绩单的最大尺寸。PRR内单个DNA元件的变化可能对这些参数中的每一个产生实质性影响。鉴别区和-10元件主要分别影响位置2-5和6-10处的流产概率，而-10和-35保守六聚体和间隔区影响位置11-15处的流产概率。令人惊讶的是，与在共有六聚体中携带哪怕一个偏差的启动子变体相比，共有启动子的转录总是会产生更高的流产率、更高的流产概率、更长的流产阶梯和更低的生产率。这些结果表明，强的RNA聚合酶-PRR相互作用使聚合酶在启动子处停滞，从而降低启动子逃逸的速率，并因此提高失败起始的程度。
Abortive initiation and promoter escape are two principal biochemical reactions occurring in the latter stage of transcript initiation. We have analyzed the influences of individual DNA elements within the promoter recognition region (PRR) on these reactions by measuring the quantitative initiation parameters that describe abortive initiation and promoter escape; these parameters are the abortive rate, the productive rate, the abortive:productive ratio, the abortive probability, and the maximum size of abortive transcripts. Changes in the individual DNA elements within the PRR can have a substantial effect on each of these parameters. The discriminator region and the -10 element primarily influence the abortive probability at positions 2-5 and 6-10, respectively, while the -10 and -35 conserved hexamers and the spacer region affect the abortive probability at positions 11-15. Surprisingly, transcription of a consensus promoter invariably gives a higher abortive yield, a higher abortive probability, a longer abortive ladder, and a lower productive rate than promoter variants carrying even a single deviation in the consensus hexamers. These results suggest that strong RNA polymerase-PRR interactions stall the polymerase at the promoter, thereby reducing the rate of promoter escape and consequently enhancing the extent of abortive initiation.