大肠杆菌rrnB P2启动子的调控
Regulation of the Escherichia coli rrnB P2 promoter.
作者信息
Murray Heath D, Appleman J Alex, Gourse Richard L
机构信息
Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, WI 53706, USA.
出版信息
J Bacteriol. 2003 Jan;185(1):28-34. doi: 10.1128/JB.185.1.28-34.2003.
The seven rRNA operons in Escherichia coli each contain two promoters, rrn P1 and rrn P2. Most previous studies have focused on the rrn P1 promoters. Here we report a systematic analysis of the activity and regulation of the rrnB P2 promoter in order to define the intrinsic properties of rrn P2 promoters and to understand better their contributions to rRNA synthesis when they are in their natural setting downstream of rrn P1 promoters. In contrast to the conclusions reached in some previous studies, we find that rrnB P2 is regulated: it displays clear responses to amino acid availability (stringent control), rRNA gene dose (feedback control), and changes in growth rate (growth rate-dependent control). Stringent control of rrnB P2 requires the alarmone ppGpp, but growth rate-dependent control of rrnB P2 does not require ppGpp. The rrnB P2 core promoter sequence (-37 to +7) is sufficient to serve as the target for growth rate-dependent regulation.
大肠杆菌中的七个核糖体RNA（rRNA）操纵子各自包含两个启动子，即rrn P1和rrn P2。以往大多数研究都集中在rrn P1启动子上。在此，我们报告了对rrnB P2启动子活性和调控的系统分析，以确定rrn P2启动子的内在特性，并更好地理解当它们处于rrn P1启动子下游的自然环境中时，对rRNA合成的贡献。与之前一些研究得出的结论相反，我们发现rrnB P2是受调控的：它对氨基酸可用性（严格控制）、rRNA基因剂量（反馈控制）以及生长速率变化（生长速率依赖性控制）均表现出明显的响应。对rrnB P2的严格控制需要警报素鸟苷四磷酸（ppGpp），但对rrnB P2的生长速率依赖性控制不需要ppGpp。rrnB P2核心启动子序列（-37至+7）足以作为生长速率依赖性调控的靶点。
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