Increased rrn gene dosage causes intermittent transcription of rRNA in Escherichia coli.
Increased rrn gene dosage causes intermittent transcription of rRNA in Escherichia coli.
复制标题
rrn 基因剂量的增加会导致大肠杆菌中 rRNA 的间歇性转录。
DOI：
10.1128/jb.181.14.4170-4175.1999
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发表时间：
1999
影响因子：
3.2
通讯作者：
Squires,CL
中科院分区：
文献类型：
--
作者：
Voulgaris,J;French,S;Gourse,RL;Squires,C;Squires,CL
当通过在多拷贝质粒上添加 rRNA (rrn) 操纵子来增加大肠杆菌细胞中的 rRNA (rrn) 操纵子数量时，每个操纵子的 rRNA 表达率会降低，以维持细胞中 rRNA 的恒定浓度。我们使用电子显微镜检查了含有携带rrnB 的多拷贝质粒的细胞中的rRNA 转录。我们发现转录基因的 RNA 聚合酶分子较少，正如之前的基因剂量研究所预测的那样。此外，RNA聚合酶分子沿着操纵子排列成不规则间隔的组。没有观察到明显的停顿或转录终止位点，这些位点可以解释聚合酶分子组的不规则间距。我们还发现，当Therrngene剂量增加时，总体转录延伸率没有变化。我们的数据表明，当rrn基因剂量增加时，起始事件或启动子近端延伸事件会以不规则的时间间隔中断。
When the number of rRNA (rrn) operons in anEscherichia colicells is increased by adding anrrnoperon on a multicopy plasmid, the rate of rRNA expression per operon is reduced to maintain a constant concentration of rRNA in the cell. We have used electron microscopy to examine rRNA transcription in cells containing a multicopy plasmid carryingrrnB. We found that there were fewer RNA polymerase molecules transcribing therrngenes, as predicted from previous gene dosage studies. Furthermore, RNA polymerase molecules were arranged in irregularly spaced groups along the operon. No apparent pause or transcription termination sites that would account for the irregular spacing of the groups of polymerase molecules were observed. We also found that the overall transcription elongation rate was unchanged when therrngene dosage was increased. Our data suggest that whenrrngene dosage is increased, initiation events, or promoter-proximal elongation events, are interrupted at irregular time intervals.